High-power low-RPM DC motor

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HIGH-POWER LOW-RPM DC MOTOR motorS utilized two sets of electromagnets to produce their

CROSS-REFERENCES TO RELATED

torque. One Set was mounted to the inside of the motor casing. These electromagnets had one set of poles facing

APPLICATIONS inward, and the other Set of poles against the Steel casing to This application is a divisional application of U.S. patent magnetically connect them in Series. The motor casing with application Ser. No. 09/088,096 filed Jun. 1, 1998, now U.S. When its electromagnets made up the Stator portion of the motor. Pat. No. 6,037,692 which application is a continuation-in power was on, these electromagnets maintained the part application of U.S. patent application Ser. No. 08/991, Same field. At each end of the motor casing were end caps having holes which were centrally located which Supported 926 filed Dec. 16, 1997, now U.S. Pat. No. 5,903,118, issued a bushing or bearing through which the rotational portion (or May 11, 1999. rotor) was Supported. The rotor consisted of a round shaft BACKGROUND OF THE INVENTION having a larger diameter Set of electromagnet windings 1. Field of the Invention wound onto an iron core. The ends of the rotor windings were fixed to conductive copper Strips that were insulated

The present invention relates to electric motorS and, more 15 from each other and the motor casing using resin or other particularly, to direct current electric motorS Suitable for Suitable insulating material. A set of brushes which were reliably and efficiently powering electric Vehicles and indus usually made of graphite pushed up against the copper Strips trial machinery. in the rotor to make electrical contact while also allowing the 2. Description of Related Art rotor to rotate. The position of the brushes relative to the There are numerous electric motors available for propel Stator electromagnet windings was always Set So that the ling electric automobiles. These include both direct current proper rotor electromagnets were turned on at the appropri (DC) motors designed to drive directly off of the batteries ate times by the brushes to always magnetically drive the and alternating current (AC) motors which require electrical rotor in the same direction (i.e., by interaction of the Stator circuitry for converting the DC power in the batteries to AC magnetic field with the magnetic field of the electromagnets power. The most efficient of these AC motors requires three 25 in the rotor).

or more phase power. While these motors were suitable for powering both Such motors have a high power-to-weight ratio, can be electric cars, as well as industrial equipment, Their effi made to run efficiently, and are inherently reliable because of ciency was Somewhat limited by the fact that power losses their brushless design. A disadvantage of Such motorS is the occurred in both Sets of electromagnets due to the resistance fact that the battery power must be first converted to AC of their windings.

before it can be used by the motor. This disadvantage shows In the early 1930s, the General Electric Company devel up in the need for complex circuitry. This is especially true oped the first permanent magnets that were strong enough to for AC motors having three or more phases. Along with the replace one set of electromagnet windings in DC motors. need for complex circuitry is the fact that the failure of even This Permanent magnet material was called Alnico, and a single electrical component in the System can result in total 35 Soon Several grades were made commercially available. failure of the drive circuitry for producing AC power. This Shortly thereafter, the first useful permanent magnet motors results in DC electric power in the batteries, and a motor that began to appear. These motors basically used permanent requires AC power. This renders the entire drive System magnets to replace the Stator electromagnets. While these useleSS. motorS had an increased efficiency when compared to their Therefore, such drive systems suffer from the potential of 40 predecessors, they Suffered from the possibility of demag leaving the driver Stranded. Despite these obstacles, com netization of the permanent magnets if the electromagnetic panies Such as AC Propulsion Inc. have made considerable field in the rotor exceeded the “coercive force” (a measure advances in the use of AC motors in electric cars. In of the resistance to demagnetization of permanent magnets) particular, high power to weight ratioS have been achieved. of the permanent magnets in the Stator. To partially alleviate In the powering of industrial machinery, in many appli 45 this problem, Stronger ceramic permanent magnets were cations it is desirable to have an electric motor that has developed, and Still Stronger magnets called “Rare Earth considerable amounts of torque and power at relatively low Magnets' are among the most recent developments. RPM values. This is normally achieved by gearing the motor All DC permanent magnet motors run the risk of demag down, however this practice results in added moving parts, netization of their permanent magnets if the electromagnetic increased mechanical losses, and adds cost and complexity 50 field of the windings exceed the coercive force of the to the overall System. In general DC electric motors have permanent magnets. To alleviate this problem, a maximum good torque characteristics which make them ideal for use in Safe operating Voltage for any DC permanent magnet motor many industrial applications. In general with DC electric is specified which under maximum power conditions (i.e., at motors, the more mechanical drag on the motor, the more Stall) the resistance of the electromagnet windings will be torque is produced. In this respect Such motors are ideal for 55 high enough to prevent a flow of current through the propelling electric cars as well. This is especially true if one electromagnet Sufficient to cause irreversible damage to the wants to drive the wheels of such a vehicle directly by permanent magnets. This current is considerably greater employing a motor in the wheel hub. There are Several than the normal operating current, and for this reason, reasons why DC electric motors are advantageous. normal operating conditions for traditional permanent mag DC electric motors require little circuitry to drive them 60 net DC electric motors only utilize a fraction of their true from batteries. In some cases they can be wired directly with power capabilities based on their permanent magnets. In only a Switch to tun the System on and off. Another advan fact, most of these motors only utilize between 10% and tage offered by DC electric motors is the fact that such 25% of their true potential.

motorS do not require Starting circuitry in the way that many The wire diameter used in winding an electromagnet core AC motors do. 65 basically determines the magnetization force in ampere The first electric cars were produced at the turn of the turns for a given cross-sectional core diameter at a given century and were powered by DC electric motors. Such Voltage. Increasing the number of turns reduces the number

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of amperes that will flow through the coil, but increases the AS is, this motor can withstand 20 amperes through its number of turns thus, maintaining the same number of electromagnet windings before demagnetization effects ampere-turns. In order to more effectively use the permanent destroy the Stator permanent magnets. With an armature magnets of a permanent magnet motor under normal running resistance of 2.4 ohms (measured at Stall) this gives a conditions (i.e., at 10% to 25% of stall current) electromag maximum Safe operating Voltage of 48 volts without the risk net windings must be activated that are more than capable of of damaging the Stator permanent magnets. Of course other demagnetizing the permanent magnets in the motor under factors need to be considered before exceeding the manu the conditions of stall. One way to accomplish this is to wind facturerS Specifications, but this electric motor can handle the electromagnet in layers and using thinner wire Succes Stall at 48 volts before demagnetizing the Stator permanent Sively in the outer layers. On Start up, all the layers of wire magnets. This gives a power rating considerably higher than in the electromagnet are used. The resistance of the thinner the original manufacturerS Specifications. If one wants to run outer wire prevents excessive currents in the motor thus this particular motor at 48 volts and at 25% of stall torque preventing demagnetization of the motor permanent mag (Maximum mechanical work output before excessive volt nets. Once the motor RPM value reaches a safe level, the outer layers are shunted, thus increasing ampere turns in the 15 5ageamperes, drops across the windings occur) at 48 volts, and about 240 watts of power will be delivered to the motor motor and increasing the utilization of the motor permanent at 1,500 RPM with an approximate efficiency of 75%, magnets. An interlock is also provided that prevents acci dental activation of the shunt mechanism under Stall or low producing 180 watts of mechanical work and 60 watts of RPM conditions. Other methods may be employed to wind waste heat being generated in the motor windings. In this electromagnet cores providing this type of electromagnet. case the permanent magnet utilization during running is 25% Also included is twisting two or more Strands of a given of their true capability. If one wants to increase the torque thickness insulated electromagnet wire together and winding output at this RPM value, it is necessary to further utilize the the core. At one end the two Strands are connected. This Stator permanent magnets during running. This can be becomes the common. At the other end, the two leads are accomplished using motor windings in the armature that are kept Separate. On motor Start up, only one lead is connected. more than capable of demagnetizing the Stator permanent Once motor RPM values reach a safe level, the second lead 25 magnets under Stall conditions, and not fully activating these is connected to the first thereby increasing the utilization of windings until the motor RPM reaches a safe value that will the permanent magnets by providing more ampere-turns in not demagnetize the Stator permanent magnets. The follow the motor electromagnet assembly. ing theoretical analysis will illustrate this point. This increased utilization of permanent magnets during An arbitrary number of 100 turns is chosen for the wire running conditions results in an electric motor having excep that wraps the electromagnet core. This gives a value of tionally high torque values. The example outlined below will 2,000 ampere-turns before demagnetization occurs. A wire be used to further illustrate this point. diameter is chosen to wrap the electromagnet rotor core that Ametek Corporation is a major manufacturer of electric is half the resistance of the original wire. If the same number motors. They manufacture a DC permanent magnet motor of turns are used, (100) an armature resistance of 1.2 ohms which is nominally rated at 24 volts. #116281-00. It is 35 would be the result. Since the same number of turns is used, reversible and has a no load speed of 980 RPM. Measure if 48 volts is applied to the armature windings under Stall ment of the armature resistance under Stall conditions gives conditions, 4,000 ampere-turns would result. Twice the 2.4 ohms. According to the manufacturerS Specifications, it magnetic field needed to demagnetize the Stator permanent is desirable to run this motor at 750 RPM. This value magnets (assuming that core Saturation effects are represents about 25% of stall torque at 24 volts input. Under 40 negligible). Now this particular motor as is would not be these conditions, 2.75 amperes of current flow through the suitable for running at 48 volts because if even 50% of stall motor windings. The Voltage drop is equal to the Resistance torque is achieved, the Stator permanent magnets will be at in ohms times the current in amperes. This is equal to 2.4 least partially demagnetized. A Second Set of electromagnet ohmsx2.75 amperes=6.6 volts. This leaves 17.4 volts for windings is employed in Series with the first Set of windings contributing to mechanical work giving the motor an effi 45 using wire of three times the electrical resistance as the first ciency of about 73%. The mechanical output when using this original Set. This Set of windings is then wound with the motor under the manufacturers recommended Voltage, same number of turns (100) as the first set giving a resistance torque, and RPM values is 2.75 amperesx24 voltsx0.73 of 3.6 ohms. The total resistance of the two windings efficiency factor to give 48 watts or about 0.063 horsepower. combined is 4.8 ohms. Since the electromagnet core has Running under the conditions of less torque increases motor 50 twice the number of original turns, (200) in terms of efficiency however is detrimental to power output. Loading demagnetization (2000 ampere-turns) this motor would have down the motor to increase torque has the effect of trading a safe operating current of 10 amperes. With an armature torque for RPM which results in virtually no increase in resistance of 4.8 ohms, a maximum operating Voltage of 48 mechanical work output accompanied by a rapid increase in volts can be employed under the conditions of stall without power losses in the motor windings. 55 demagnetizing the Stator permanent magnets. Accordingly, The manufacturer also provided the maxi Now assume that at Start up, this particular motor is mum current before demagnetization occurs in the motor. connected to a 48 volt power Source. At Start up, all of the This occurs at a current of 20 amperes through the windings. windings are activated causing a current of 10 amperes to Note the fact that up to 20 amperes can be delivered to the flow. 2,000 ampere-turns results in the electromagnet which motor before damaging the permanent magnets, but the 60 is just shy of the magnetic field needed to demagnetize the manufacturer also specifies the best load value to run the Stator permanent magnets. The rotor under this strong mag motor at is 2.75 amperes. Therefore during normal running netic field Starts to Spin rapidly, and the current along with conditions, only 13.7% of the capability of the permanent its associated magnetic field Starts to weaken. At Some RPM magnets are utilized. This indicates that under the proper value, it is now Safe to shunt out the outer high resistance conditions that this motor can put out 7.3 times this torque 65 turns of wire thus activating only the lower resistance inner value at this RPM value before demagnetizing the stator turns. Since 25% of stall current is the desired operating permanent magnets. range, and the rotor electromagnets have the Same number

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S 6 of turns as the original motor, at 1,500 RPM the motor Another alternative is to construct a DC permanent mag efficiency is 75%, but the torque is twice the value as the net motor having the permanent magnets in the rotor and the original motor, and the permanent magnets are being utilized electromagnets in the Stator as is done with brushleSS at 50% instead of 25%. This motor is now putting out twice designs but use a brush System for timing. The timing Signal the power as it was originally. 480 watts of input power is is then amplified electronically using transistors. This elimi providing 360 watts of mechanical work accompanied by nates many of the problems in brush timed motors by 120 watts of waste heat. This method of increasing the Significantly reducing the power that flows through the brush power output of permanent magnet motorS is quite effective. commutator system. This allows the brushes to be made This process however needs to be made user friendly. This from Such materials as conductive kapton polyimide film, requires that the end user of Such motorS does not have to and also for the use of commutators made from copper clad think about damaging Such motors by fully activating the circuit board material. With this type of hybrid brush timing lower resistance motor windings. In order to accomplish this System, keeping the inverted design features normally found end, interlocking circuitry is needed in order to prevent the in brushleSS motorS is beneficial when employing multiple accidental demagnetization of permanent magnets in these winding electromagnets.

permanent magnet motorS. 15

BrushleSS permanent magnet motors are ideal for increas

Another example of how this approach can yield positive ing ing permanent magnet utilization during running by employ the teachings of this invention. With the electromagnets results would be to employ the thick inner windings of the in the Stator instead of the rotor, the use of multiple elec previous example with its thinner associated outer windings, tromagnet but only run the motor at 12.5% of stall instead of 25% of Switching windings is easily achieved. In addition Since the of the electromagnets is now achieved using stall. In this way, this electric motor would utilize the electrical Switching circuitry, interlocking of the individual permanent magnets by only 25%, the same utilization as the electromagnet windings becomes a relatively easy task to original motor without these modified windings. The motor perform. Speed Sensing is critical as it is now used as a efficiency, however would be significantly improved from determining factor in the interlocking of various electro about 75% to 88%. As now the thicker electromagnet magnet winding configurations. This serves the all important windings would have leSS resistive losses. Of course the 25 function of protecting the permanent magnets from acciden Same precautions to guard against demagnetizing the per tal demagnetization. Several Speed Sensing and interlocking manent magnets would have to be taken. approaches may be used. For example, for relatively large In these particular cases, the connections to the electro motors, a Small electric generator may be placed onto the magnet windings are difficult to achieve because the elec power output shaft of the motor and wired to a relay which tromagnet is embedded into the rotary part of the motor. Not closes the appropriate contacts at a predetermined generator that this cannot be achieved, can, in at least two different output voltage. This System is a good choice because if any ways. of the Speed Sensing components fail, the high power In the first method, two different and complete sets of both electromagnet windings are interlocked out and the motor brushes and commutators may be employed. This is not a while not being able to go into the high power mode will not preferred method of implementing the high magnetic utili 35 be damaged by the accidental premature activation of these Zation aspects of this invention. Brushes and commutators high power electromagnet windings. Another Similar option are a major Source of motor wear and maintenance prob for Speed Sensing is to place a Small coil of wire on a lems. Adding on another Set would add complication and ferromagnetic core which is placed close enough to the increase the overall need for motor maintenance. A better permanent magnet rotor to generate an output voltage which approach would be to employ an internal centrifugal Switch 40 is proportional to speed. This Sensor then becomes the that switched the motor windings only when the RPM value electromagnet portion of a permanent magnet generator reached a Safe level. Such Switches are commonly used to which uses the rotating rotor permanent magnets as its own. lock out motor Starter windings in many Single phase AC According to another aspect of this invention a high induction motors. Although two methods of using this power DC electric motor which is suitable for powering System are described above, it is far easier implemented in 45 electric automobiles as well as industrial machinery is DC permanent magnet motors of brushleSS design. In Such provided. This particular electric motor describes the use of electric motors, the electromagnets make up the Stationary a large diameter planar rotor employing built in air moving part of the motor or Stator, and the permanent magnets make Vanes to provide cooling to Stator electromagnets. up the rotating portion of the motor or rotor. All electric motorS have resistive losses in their electro BrushleSS DC electric motors are permanent magnet 50 magnet windings which generate considerable amounts of motors which employ their permanent magnets into the heat. Because of this generation of heat, many motors both rotating portion (rotor) of the motor and their electromagnets AC and DC, are equipped with a Small fan blade mounted into the stationary portion (Stator) of the motor. This results onto the motor shaft on the inside of the motor to move air in a design which is inverted from traditional permanent through the motor for the purposes of cooling. In the case of magnet motors. Because the electromagnets used in Such 55 DC motors, the greatest amount of heat is generated under motors are Stationary, no electrical power needs to be high load conditions. Because of this fact, coupled with the provided to any moving parts. This elimination of brush fact that under Such conditions motor RPM values are low, timed commutators is accomplished by Switching arrange insufficient volumes of air are available to adequately cool ments which are comprised of a rotor position Sensor and the motor. This leads to the undesirable risk of overheating transistor Switching circuitry. Several methods may be 60 the motor under heavy load conditions. Because of this, it is employed for Sensing rotor position including Hall effect often practice to mount an external fan powered by a Sensors, and photocell gates. Transistor Switching circuitry Separate power Source to continuously blow high volumes of usually consists of transistors for the actual Switching of air through the motor. Although efficient for motor cooling power to the Stationary electromagnets along with diode under low RPM heavy load conditions, the extra fan motor protecting circuitry which protects the transistors from tran 65 adds to the complication of the System. Sient back Voltage Spikes that are often associated with the In addition to the overheating issue, the overall power of rapid Switching of electromagnets. DC permanent magnet motorS is proportional to the amount

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of permanent magnet material that can be magnetically with induced magnetic poles. Materials having high mag cycled through the field produced by the electromagnets. To netic permeability lower the overall field energy of the achieve a high rate of magnetic cycling at relatively low electromagnets by completing their magnetic circuit. This RPM values, employing a large diameter rotor is beneficial. field energy shows up as mechanical work. Although the risk Increasing the rotor diameter increases the Surface Speed of demagnetization is alleviated in Switch reluctance motors, at the edge allowing a high Volume of airflow to be easily large Voltage Spikes are produced during electromagnet achieved by adding air moving Surfaces about the periphery. Switching. These Spikes represent large amounts of energy This airflow is needed to cool the motor. For high power which can damage circuit components, create exceSS heat, output applications, further cooling may be necessary. and negatively affect motor efficiency. To alleviate this Blades, rotary Vanes, or even an internal turbofan can be problem, high frequency chopped DC power, or even AC added to achieve this. power can be Supplied to the electromagnets where the cycle Several electromagnet to permanent magnet geometries rate is considerably higher than the motor timing Switching may be employed. For example, the permanent magnets may rate. In other words, during Single electromagnet on times, be placed facing outward in a radial configuration at the multiple electric pulses occur.

periphery of a large diameter disc. With this permanent 15 With all of these planar rotor geometries, high Surface magnet configuration, the electromagnets are placed around Speeds around the periphery of the rotor are easily achieved the periphery with their poles facing inward in a radial along with considerable forces in a radial direction during direction. In this particular situation, rotary Vanes could be running. As an example, a 24" diameter rotor rotating at added around the periphery on the top side and/or the bottom 3,000 RPM will have a surface speed at the edge of about Side of the permanent magnets for the purposes of moving 200 miles per hour. With 5 pounds of permanent magnets air over the exposed top and bottom Surfaces of the elec around the periphery, in addition to a couple of pounds of tromagnets in the Stator. other materials, about 27,000 pounds of centrifugal force Another possibility is to use a Star Shaped electromagnet would be present in a radial direction. Because of these in the center, and use a ring of permanent magnets that radial forces, Strong materials need to be used in the fabri travels on the outside periphery of the centrally located 25 cation of the rotary portions of these large diameter planar electromagnets. In this configuration it is best practice to rOtOrS.

employ a central turbofan design to the rotary portion which One Solution is to employ composite materials. Such as pumpS air over the central windings from top to bottom. carbon fiber. These materials are Strong and lightweight. Another geometry which can be employed is to place the They do not easily conduct electricity like metals and permanent magnets into the periphery portion of a large therefore would not contribute to inductive losses. With diameter flat disc with their direction of magnetization Some rotor permanent magnet geometries flat Steel Sections transversing through the disc. The desired electromagnet can be Sandwiched on both Sides by permanent magnets. shape in this particular situation is one that forms the shape With other permanent magnet rotor geometries, a steel band of a “C” and straddles the periphery of the disc with the can be used for the purposes of holding the permanent permanent magnets traveling through the slot. In this case, 35 magnets in place as well as magnetically connecting them in air moving Vanes can be added which protrude radially past Series with each other for the purposes of concentrating their the periphery of the disc to move air within the channel of magnetic flux to the desired area of the motor. Although Steel the electromagnets to provide adequate cooling. One par is normally not a good choice due to its electrical and ticularly interesting approach to utilizing air cooling with magnetic properties, when Sandwiched between two perma this particular motor geometry is to fasten flexible plastic 40 nent magnets or employed outside of the directly applied film Vanes to the periphery of the disc. These plastic Strips magnetic field of the electromagnets, it will Somewhat resist are initially made to protrude from the edge in a radial the losses normally present when Solid Steel is Subjected to direction. These flexible plastic Strips move modest quanti rapidly changing magnetic fields. In this respect the Steel ties of air past the electromagnets under low RPM condi used under these conditions behaves in a similar manner to tions. AS the rotor Velocity increases, aerodynamic drag 45 the Steel casing in ordinary DC electric motors. It becomes bends these Strips back. This alters their shape, reducing part of the magnetic circuit, however being Somewhat their drag effect on the rotor, however, enough airflow is still Shielded from changing magnetic fields, does not apprecia maintained to prevent overheating of the electromagnets. bly add either to inductive or hysteresis loSS. For example, In addition to permanent magnet motors, the large diam a hub drive System for one or more wheels in an electric eter planar rotor geometries employing added air moving 50 vehicle can be easily employed using a Steel wheel rim Surfaces are also Suited for use in “Switch Reluctance' having permanent magnets mounted against the inside por motorS. Switch reluctance motors are electric motors of tion. The permanent magnets are placed next to each other brushleSS design where a non-magnetizable material having on the inside of this rim having opposite polarity. The Steel a high permeability is employed in the rotor in place of the in the rim then magnetically connects these permanent permanent magnets. These materials include Silicon Steel, 55 magnets in Series. A Starshaped electromagnet is mounted in Soft iron, magnetically Soft ferrite, and others. Such mate the center and bolted onto the vehicle frame. The rim portion rials become magnetic only when they are in the presence of of Such a wheel is mounted to the hub portion using large an externally applied field. The familiar magnetic attraction Structurally strong air moving Spokes which provide air between a permanent magnet and Steel is an example of the cooling by pumping air over the electromagnet assembly principle utilized in Switch reluctance motors. In Such 60 while the vehicle is in motion. This hub drive system has no motors, only attractive forces are generated. Because of this, gears, and therefore attaining high torque values becomes the Switching Sequence as well as the Spacing of the high critical. In achieving this end, utilizing electromagnet wind permeability material in the rotor is somewhat different from ings which are capable of demagnetizing the rotor perma that which is employed in brushless electric motors having nent magnets at Stall and interlocking may be of benefit. This permanent magnets. Switch reluctance magnetic attraction 65 particular open motor design provides cooling, however WorkS because while the non-magnetizable high permeabil Such open motor designs must be made Somewhat resistant ity material is in the field, it becomes a temporary magnet to the elements.

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AS mentioned earlier depending on motor geometry, it motor at a given voltage and RPM value. This increase in may be desirable to move air by employing a turbofan as the torque translates directly to an increase in power to weight central portion of the planar rotor. This works well when the ratio. This increase in torque also reduces the amount of Star shaped electromagnet geometry is used in the center of gearing needed to produce a given torque output from a gear the motor with the rotor permanent magnets rotating around reduction box.

the periphery of the centrally located Stationary electromag Increasing the power to weight ratio of permanent magnet nets. It is desirable that Such a turbofan is capable of moving DC electric motors has traditionally been achieved by large Volumes of air over the electromagnets while running increasing the running RPM value of the motor. This at relatively low RPM values. approach has worked well because the power output of Such An example of such a turbofan is outlined in U.S. Pat. No. motorS is dependent on three parameters. 5,075,606 by Leonard H. Lipman in which the author uses 1. The field Strength of the permanent magnets. this turbofan design to move large Volumes of air at low 2. The total Volume of permanent magnet material that is RPM values by maximizing the available cross section. The cycled through the field of the motor electromagnets in a impeller portions of Such a turbofan are ideal for cooling the given period of time.

large-diameter DC permanent magnet motor of this inven 15 3. The field strength of the electromagnets during running. tion having the above described geometry. Designing permanent magnet DC electric motors to run at In View of the foregoing, it is an object of this invention high RPM values directly increases power output by increas to provide a DC permanent magnet electric motor having a ing the amount of permanent magnet material that is cycled high power to weight ratio. through the field of the motor electromagnets in a given It is a further object of this invention to provide this high period of time. Unfortunately this method while effective at power to weight ratio at relatively low RPM values. increasing motor horsepower has Some undesirable conse It is a further object of this invention to provide a means quences and may not be best Suited for every application. of increasing the utilization of permanent magnet material in 1. Motor torque is Still limited requiring a high amount of DC permanent magnet motors. 25 gear reduction for use in low RPM applications. According to another aspect of this invention, it is an 2. Running such motors at high RPM values results in object of this invention to provide a large diameter planar high motor bearing Surface Speeds which presents added rotor which is driven from the edge to further increase motor maintenance problems.

power at relatively low RPM values. 3. High RPM motors quite often produce excessive acous It is yet another object of this invention to employ added tical noise.

air moving Surfaces which provide air cooling to the large 4. Many such motors tend to overheat if run at these high diameter planar DC permanent magnet motors outlined in Speeds for prolonged periods of time.

this aspect of the invention. 5. Internal windage losses (aerodynamic drag on the SUMMARY OF THE INVENTION 35 rotor) can rob Such electric motors of their power. 6. Running brush timed motors at high RPM values

In Summary, the present invention provides two methods results in rapid wear of both the brushes and commutator. that can be used either alone or combined which result in permanent magnet DC electric motorS having exceptionally during runningthe

Increasing

effective permanent magnet utilization permanent magnet DC electric motors can high power to weight ratios while running under relatively 40 be used to increase power during running without the need low RPM values. to increase motor RPM values. This is outlined in the first According to one aspect of the present invention, a portions of this Summary. This approach while effective can permanent magnet motor has demagnetizing windings and still lead to an undesirable overheating of the motor. This interlocking circuitry. Other aspects of the invention include approach also requires added circuitry to prevent the acci all large-diameter planar rotor motors employing added air 45 dental activation of demagnetizing electromagnet winding moving Surfaces in the planar portion of the rotor. configurations.

In the first method, motor electromagnets are provided The Second method of increasing motor torque at rela with two or more Sets of electromagnet windings. One tively low RPM values involves increasing the rate of configuration of electromagnet windings is capable of permanent magnet material that is cycled through the field of demagnetizing the motor permanent magnets at Stall, while 50 the electromagnet. This is accomplished by employing the other configuration is not. The first configuration is motor geometries which are flat and relatively large in interlocked out during motor Starting using an interlocking diameter. Such geometries easily allow for air cooling by mechanism. Such mechanisms include centrifugal Switches providing the planar rotary portion of the motor with fixed or multiple Sets of brushes and commutators for traditional air moving Surfaces. This provides adequate air cooling to brush timed motors, or alternatively relay Switching from 55 the electromagnets without the need for external cooling RPM sensing circuitry for DC electric motors of brushless fans.

design. The interlocking mechanism prevents the pre-mature In addition to providing fixed air moving Surfaces on the activation of demagnetizing electromagnet configurations. rotor to provide airflow over the electromagnets, air direct Once a safe RPM value has been achieved that allows the ing cowling may also be employed to control the direction higher Strength electromagnet winding configuration to be 60 of air coming into, going through, and exiting the high activated without the risk of demagnetizing the motor per powered planar air cooled motor outlined in this aspect of manent magnets, the interlock is deactivated. This allows this invention. For example, In industrial applications activation of the Strong electromagnet configuration, or involving the machining of parts, it may be desirable to alternatively automatic Switching to this mode can be re-direct airflow from the motor away from where it may achieved during running. 65 objectionably blow shavings, Sawdust, or chips into This procedure results in an increase in the amount of unwanted areas. When using Such motors to power electric torque that can be delivered by a given permanent magnet automobiles, the warm exit air from the motor may be a

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Source of desirable heat that can be used to maintain a useful FIG.21 shows a smooth rotary disc rotor of this invention battery temperature or for interior heating applications. incorporating a non-magnetizable high permeability mate

BRIEF DESCRIPTION OF THE DRAWINGS

rial in the periphery to provide mechanical power by Switch reluctance.

FIG. 1 shows the magnetic flux paths in the stator 5 FIG. 22 shows a rotary disc rotor having a rough texture assembly of a brush timed permanent magnet DC electric Surface incorporating a non-magnetizable high permeability motor. material in the periphery to provide mechanical power by FIG. 2 shows the magnetic flux path of one of the stator Switch-reluctance.

electromagnet assemblies of this invention. FIG. 23 shows the rotary portion of a brush timed FIG. 3 shows a detailed drawing of the stator portion of permanent magnet motor having two Separate electromagnet the motor of this invention. windings wrapped around the core each having their own Set FIG. 4 shows the rotary disc portion of the motor of this of commutators, and a centrifugal Switch. invention with built in impeller. FIG. 24 shows the rotary portion of a brush timed FIG. 5 shows a diagram of circuitry needed to drive the 15 permanent magnet motor having added windings which are high-powered DC turbofan cooled motor of this invention. made from thicker wire than the first Set along with a FIG. 6 shows a Stator electromagnet having multiple centrifugal Switch.

windings of differing wire diameter for increasing motor FIG. 25 shows a brush timed permanent magnet electric torque at high RPM values. motor employing a rotor having two separate electromagnet FIG. 7 shows an overall diagram of the high-powered DC windings, and a centrifugal Switch for activating both Sets of windings at a pre-Set value.

turbofan cooled motor of this invention.

FIG. 8 shows an overall diagram of the high-powered DC electric FIG. 26 shows a brush timed permanent magnet DC turbofan cooled motor of this invention having two rotor thicker wire motor having added windings which are made from discS mounted onto the same central shaft. than the first set.

FIG. 9 shows a diagram of the armature of the motor of typical brushleSS permanentthe stationary electromagnet portion of a this invention having short flexible blades emanating radi ing added electromagnet windings magnet DC electric motor hav ally from the edge of the rotor which allows for adequate thicker wire than the first set. which are made from cooling under low RPM values but which limits air flow FIG. 28 shows the stationary electromagnet portion of a under high RPM values to prevent excess power consump tion. typical brushleSS permanent magnet DC electric motor hav FIG. 10 shows a current sensing device which prevents ing of electromagnet windings made from twisting two Strands electromagnet wire together.

accidental demagnetization of the rotor permanent magnets at low speeds. FIG. 29 shows the stationary electromagnet portion of a FIG. 11 shows the rotary portion of the motor of this 35 employing two setspermanent typical brushleSS magnet DC electric motor invention having a toothed edge for engagement to a gear or electrically isolated from each other. windings which are of electromagnet cog belt.

FIG. 12 shows the rotary portion of the motor of this typical FIG. 30 shows the permanent magnet rotary portion of a invention consisting of a disc having a Smooth Surface. brushless DC electric motor. FIG. 13 shows the rotary portion of the motor of this 40 FIG. 31 shows a typical DC brushless electric motor invention consisting of a disc having a roughened Surface to employing added electromagnet windings which are made increase airflow. from thicker wire than the first set along with an interlock mechanism.

FIG. 14 shows the top view of an optical encoder disc FIG. 32 shows the rotary portion of a large diameter along with photocell gates to provide timing for the high brushless DC electric motor consisting of a central turbofan power motor of this invention. 45 portion and permanent magnets around the periphery.

FIG. 15 shows a tilted view of an optical encoder disc and FIG. 33 shows a large diameter brushless DC electric photocell gate used to provide timing for the high power motor having a rotary portion consisting of a central turbo motor of this invention.

fan and permanent magnets around the periphery, and a

FIG.16 shows a side view of the high power motor of this centrally located Star Shaped electromagnet. invention including a Small generator on the shaft for Speed 50 FIG. 34 shows a large diameter brushless DC electric Sensing, Speed Sensing circuitry, optical timing circuitry, and motor having a rotary portion consisting of a central turbo amplification circuitry. fan and permanent magnets around the periphery, a centrally FIG. 17 is a Schematic diagram showing optical timing located Star shaped electromagnet, and added gear teeth circuitry integrated with transistor amplification circuitry 55 around the outside periphery.

which provides power to the electromagnets in the motor of FIG. 35 shows a large diameter brushless DC electric this invention. motor having a rotary portion consisting of a central turbo FIG. 18 shows an electromagnet assembly including fan and permanent magnets around the periphery, a centrally Switching circuitry having thick wire wrapped around the located Star shaped electromagnet, and teeth for engagement core to a first tap, and thinner wire wrapped over the thick 60 to a cog belt around the outside periphery. wire to a Second tap. FIG. 36 shows a large diameter air cooled electric motor FIG. 19 shows a sectional view of the edge of the disc of this invention employed in a vehicle hub drive system traveling through an electromagnet gap including permanent having a Steel rim, permanent magnets attached to the inside magnets Sandwiching a flat Steel Spoke. portion, a Star shaped electromagnet assembly which is FIG. 20 shows a multitap electromagnet having the tap 65 bolted onto the vehicle frame, and large Structural air Selection controlled by a relay which receives a voltage moving Spokes for connecting the outer rim portion to an Signal from a Small electric generator. axle assembly.

Page 29

FIG. 37 shows the rotary portion of a large diameter FIG. 5 shows a circuit diagram for properly timing and brushleSS DC motor consisting of a planar disc having Supplying power to the Stator electromagnets of this inven permanent magnets about the periphery in a radial direction, tion in order to drive the rotor. The circuit serves to initially and fixed air moving Vanes protruding from the edge. energize the coil of electromagnet 20 in one direction to pull FIG. 38 shows a large diameter brushless motor consist an adjacent permanent magnet into the field of the ing of a planar disc rotor having permanent magnets about electromagnet, and then reverses the energization applied to the periphery in a radial direction, electromagnets pointing coil 24 to push the permanent magnet out of the electro inward toward the edge of the disc, and fixed air moving magnet 20 and to pull the next permanent magnet forward. Vanes protruding from the edge of the disc which move air When permanent magnet 54 passes the Hall effect sensor 76, over the electromagnets. power from battery 66 flows through resistors 78 and 80 and FIG. 39 shows the rotary portion of a large diameter Zener diode 82 to activate opto-isolator 84. The phototrans brushless DC electric motor consisting of a central turbofan istor portion of opto-isolator 84 is wired to the gate portion portion and non-magnetizable high permeability material of MOSFET power transistor 70 through biasing resistor 86. around the periphery. Biasing resistor 86 in turn is connected to the positive side FIG. 40 shows the rotary portion of large diameter brush 15 of battery 67. Resistor 88 connects the gate of MOSFET leSS DC electric motor consisting of a planar disc having power transistor 70 to the negative side of battery 66 and non-magnetizable high permeability material embedded on Serves two purposes. One purpose is to discharge the gate the outside periphery, along with added air moving Surfaces. capacitance of transistor 70 for rapid turn off; and the other

DESCRIPTION OF THE INVENTION

purpose is to divide the battery Voltage to the gate to allow for low gate turn-on Voltages with relatively high battery

FIG. 1 shows the open magnetic circuit in the Stator Voltages.

portion of a traditional permanent magnet DC motor. Thus, when Hall effect sensor 76 is activated by perma Encased in thick Steel housing 2 are permanent magnets 4 nent magnet 54, transistor 70 is turned on with full power. and 6 having opposite poles 8 and 10 against housing 2. Also Power from batteries 66 and 67 is then delivered to elec shown are permanent magnet poles 12 and 14 which are 25 tromagnet 20 through diode 90. Electromagnet 20 then aligned with each other acroSS air gap 16. Also shown are moves the wheel forward by pulling permanent magnet 54 lines of magnetic flux 18 which travel both through the into its field. When permanent magnet 54 approaches its motor housing 2 as well as through air gap 16. Thus, the equilibrium position, Hall effect sensor 76 is shut off. The completion of flux lines 18 from permanent magnets 4 and unused magnetic energy Stored in the electromagnet shows 6 requires a thick magnetic motor housing 2 as part of the up as a reverse EMF spike. Diode 90 isolates transistor 70 magnetic circuit. from this spike. Diode 92 then shunts this spike into batteries FIG. 2 shows the flux path produced by stator electro 67 and 68 to give them a slight charge. Permanent magnet magnet 20 in the electric motor of this invention. Stator 54 passes by Hall effect sensor 74, Switching power from electromagnet 20 consists of a magnetic core 22 in the shape battery 68 though resistors 94 and 96 and Zener diode 98 to of a “C” which is wound with electromagnet wire 24. When 35 activate opto-isolator 100. The phototransistor portion of electromagnet windings 24 are energized, magnetic flux 26 opto-isolator 100 is wired to the gate portion of MOSFET is generated in accordance with the right-hand rule of power transistor 72 through biasing resistor 102. Biasing electrically induced magnetism. The magnetic flux 26 that is resistor 102 in turn is connected to the positive side of generated is contained within core 22 and emerges from pole battery 69. Resistor 104 connects the gate of MOSFET faces 28 and 30. With the electromagnet geometry shown in 40 power transistor 72 to the negative side of battery 68 for the FIG. 2, the magnet flux generated remains entirely within air purposes of draining the gate capacitance of MOSFET gap 32 of the electromagnet 20. The electromagnet geometry power transistor 72 when the gate Voltage is shut off and of this invention is based on a Rowland ring. ARowland ring divides the gate Voltage used to maintain a Safe operating was named after J. H. Rowland who made use of it in his level at the gate. Thus when Hall effect sensor 74 is activated experimental work on electricity and magnetism. A Rowland 45 by permanent magnet 54, MOSFET power transistor 72 is ring consists of a torroidal coil of wire wrapped around an turned on with full power. Power from batteries 68 and 69 iron core. The unique property of a Rowland ring is that the is then delivered to electromagnet 20 through diode 106, in magnetic flux generated is confined wholly to the core. The the opposite direction from that Supplied through transistor electromagnet design shown in FIG. 2 is a Rowland ring 70. Electromagnet 20 moves the rotor forward by pushing which has been modified into an electromagnet by removing 50 permanent magnet 54 out of its field, and pulling the next a Section to produce an air gap having opposite magnet poles Successive permanent magnet into the field. Once permanent on each side. magnet 54 has been sufficiently moved out of the field of FIG. 3 shows the stator portion 34 of the high powered air electromagnet 20, Hall effect sensor 74 shuts off power to cooled DC motor of this invention. Several electromagnets the circuit. Stored magnetic energy left in electromagnet 20 20 are mechanically fastened to end plates 36 and 38. Also 55 shows up as a back EMF spike which is isolated from shown is an opening 40 in end plate 36 which allows air to MOSFET power transistor 72 by diode 106 and is shunted flow through the motor for the purposes of cooling. Also across diode 108 into batteries 66 and 67, thus completing shown is a bearing 42 for the purposes of providing a the cycle.

mechanical Surface for Supporting the rotatable motor shaft FIG. 6 shows one of the stator electromagnets 20 of the of the rotor portion. 60 high-powered turbofan cooled DC motor of this invention. FIG. 4 shows the rotary disc portion of the motor of this Electromagnet 20 consists of a laminated iron core 22 in the invention 44 which consists of an outer portion 46 and an shape of a “C” which is wrapped with a single layer of heavy inner turbofan portion 48. Inner turbofan portion 48 consists gauge electromagnet wire 108 having ends 100 and 112. End of individual blades 50 connecting a central axle 52 to edge 112 is then electrically connected to one end 114 of a lower portion 46. Edge portion 46 has Several permanent magnets 65 gauge electromagnet wire 116 which is wound in a Second 54 mounted having their magnetic pole faces 56 and 58 on layer over the heavy gauge wire to give a free exposed end opposite sides 60 and 62 of outer disc portion 46. 118.

Page 30

FIG. 7 shows a diagram of the complete motor of this Located in the periphery of disc 138 are several permanent invention. Rotor disc 44 along the central shaft 52 is magnets 54 mounted having their magnetic pole faces 56 Surrounded by electromagnets 20 Straddling the edge of disc and 58 on opposite sides 140 and 142 of disc 138. As usual 44 in alignment with permanent magnets 54 in the rotary shaft 52 is used for power output and registration within the disc portion. Further employed are bearings 42 in end plates motor.

36 and 38. End plates 36 and 38 together with electromag FIG. 14 shows the top view of an optical encoder disc 144 nets 20 provide the stationary part of this motor. Hall effect having a central portion 146 and an edge portion 148. Edge sensors 74 and 76 provide the timing for amplification portion 148 consists of alternating opaque areas 150 and circuitry 108 and is distributed to electromagnets 20 by transparent areas 152. Also shown are two photocell gates wires 110.

FIG. 8 shows two discs 44 on a single shaft 52. Each disc 154 and 156 used to provide a signal for timing purposes. is driven by its own set of electromagnets 20. This geometry FIG. 15 shows a tilted view of optical encoder disc 144 provides high torque in a package having a limited diameter and photocell gate 154. Also shown is shaft 158 which is and also results in an overall reduction in inertia mass. directly fastened to the end of the motor shaft (not shown). FIG. 9 shows a rotor disc 44 having permanent magnets 15 FIG. 16 shows a side view of the disc rotor air cooled 54 mounted in the same configuration as those shown in motor of this invention. Disc rotor motor 160 is shown in FIG. 4. The disc of FIG. 9 does however have a solid center complete form. This particular motor includes a Small elec and fan blades 112 along the edge to provide direct cooling tric generator 162 which Senses the rotor Speed by generat to the electromagnets (now shown). Fan blades 112 may be ing a Voltage which is proportional to the Speed. Generator made of a flexible material Such as mylar, kapton, or other 162 is of the permanent magnet type and therefore requires polymer film. The flexible fan blades allow for high air flow no field windings and therefore no input power. Such a at low RPM values and reduce aerodynamic drag at high generator can be either of the DC output type, or conversely RPM values. the AC output type. In the case of permanent magnet DC FIG. 10 shows an example of current limiting circuitry output generators, a simple permanent magnet motor will Suitable for preventing accidental demagnetization of rotor 25 often Suffice. Although many Speed Sensing methods may be permanent magnets 54 (not shown). A Small laminated iron employed, the generator offers the best protection against core 112 having slot 116 is provided with several turns of failed circuit components. Such failure can cause premature heavy gauge wire 114. Magnetic poles 118 and 120 are shunting of electromagnet windings resulting in the potential formed when current flows through wire 114. Into slot 116 for demagnetization of rotor permanent magnets. The gen is placed a Hall effect Sensor 122 having Schmidt Triggering erator absolutely will not put out a given Voltage until a Circuitry which is used to Sense the magnetic field present minimum RPM value has been achieved. Failure of the within gap 116. Windings 114 on iron core 112 are wired in generator results in low or no output Voltage. This failure series with electromagnet 20 (not shown). mode will not result in premature shunting problems. Gen When an unacceptable amount of current flows through erator 162 can be wired to a relay to either automatically windings 114, the magnetic field generated in Small iron core 35 shunt electromagnet taps at a particular Speed, or interlock 112 activates Hall effect sensor 122 which grounds out the out the accidental premature shunting of electromagnet taps. gate of the corresponding MOSFET power transistor pro Generator 162 of motor 160 is wired to a control box 164. Viding power to electromagnet 20 and momentarily cuts off Control box 164 contains interlocking circuitry. Beneath the current. The Schmidt triggering aspect of Hall effect generator 162 of motor 160 is optical encoder 166. Optical Sensor 122 is advantageous in Switching the power transis 40 encoder 166 is mounted to motor shaft 152. The optical tors on and off rapidly in place of reducing the constant encoder itself is shown in detail in FIGS. 14 and 15 current flow on a continuous basis. Such Switching results in previously described. Optical encoder 166 is wired to ampli Virtually no Voltage drop acroSS circuit elements and allows fication circuitry 168 which amplifies the signal from optical the MOSFET drive transistors to run cool even under current encoder 166 and inputs the amplified signal into electro limiting conditions. 45 magnets 20.

In FIG. 11, rotary disc 124 consists of an outer disc Supported on motor shaft 52 is rotary disc 170 having portion 126 fixedly mounted to a central shaft 52 by turbofan portions of high permeability magnetic material 172 trans blades 50. Outer disc portion 126 has permanent magnets 54 versing through the edge portion of disc 170. FIG. 16 fixedly mounted into outer disc portion 126 with their particularly illustrates the plurality of C-shaped electromag direction of magnetization transversing through the disc. 50 nets 20 configured to define an inner annular channel 173. Also shown are high and low areas 128 and 130 cut into the The annular edge portion of disc 170 is rotatably disposed periphery of outer disc portion 126. These high and low within in annular channel 173. In the case of a permanent areas may be in the form of gear-type teeth or other teeth magnet motor design, high permeability magnetic material Suitable for engaging a cog-type belt or other Suitable 172 consists of permanent magnets. In the case of a Switched mechanical drive mechanism capable of engaging the outer 55 reluctance motor design, non-magnetizable ferrite, lami edge of outer disc portion 126. It should be noted that in nated Silicon Steel, or powdered iron composite may be Some instances several electromagnets (not shown) may employed. Also shown are flexible plastic fan blades 112 have to be removed to allow for mechanical coupling from which provide air currents to cool electromagnets 20. Motor the edge. end plates 36 and 38 provide Support for motor shaft 52, FIG. 12 shows a large diameter disc-shaped rotor 132 60 electromagnets 20, and motor bearings 42. The permanent having smooth top and bottom surfaces 134 and 136 respec magnets are disposed on the annular edge portion of disc 170 tively. Also shown are permanent magnets 54 in edge So that the directions of magnetization thereof transverse portion 46 of rotor 132. Permanent magnets 54 are mounted through disc 170. In addition, the poles of the permanent having their magnetic pole faces 56 and 58 on opposite sides magnets are aligned in coupling proximity to the poles of the 60 and 62 of outer disc portion 46. Also shown is shaft 52. 65 electromagnets of the Stator.

FIG. 13 shows a large diameter disc-shaped rotor 138 FIG. 17 shows optical timing circuitry integrated with having rough textured top and bottom surfaces 140 and 142. transistor amplification circuitry which provides power to

Page 31

the electromagnets in the motor of this invention. Optical diode 178 in optical Sensing gate then activateS phototrans timing gate 154 consists of a light emitting diode 174 and a istor 180 thereby supplying voltage to the gate of MOSFET phototransistor 176 Separated by a gap through which the power transistor 72 through voltage dividing resistors 102 optical timing disc passes (not shown) Such optical gates are and 104. MOSFET power transistor 72 then turns on Sup commercially available from Omron Electronics, Inc., plying power from batteries 68 and 69 to electromagnet 20 located at One East Commerce Drive Schaumburg, Ill. through diode 106. The interaction of the magnetic field 60173. Part No. EESG3 is a suitable optical timing gate, provided by electromagnet 20 and the magnetic material in although many others will work as well. The motor timing the rotor provides further propulsive force to the edge of the should be 40% on time from sensor 154, then 10% off time, rotor thereby providing mechanical power. Just before the then 40% on time from sensor 156, then 10% off time to magnetic material in the rotor (not shown) aligns itself in the complete the cycle. The motor timing itself will vary with magnetic field in the electromagnet, Optical Sensing gate the desired operating parameters, but in general the electro 156 is shut off by an opaque region of the optical timing disc magnets should be turned on slightly early with respect to (not shown). MOSFET power transistor 72 is then shut off rotor position. Remaining Stored energy in electromagnet 20 then shows up Optical timing gate 154 has its output transistor portion 15 as a reverse voltage spike. Diode 106 isolates MOSFET 176 wired to the gate portion of MOSFET power transistor power transistor 72 from this spike while diode 108 shunts 70. The choice of the exact MOSFET power transistor will this reverse voltage spike into batteries 67 and 68 thus depend on the requirements of the particular motor. Inter completing the cycle.

national Rectifier located at 233 Kansas Street., El Segundo, The timing of actual Switching is fundamentally different Calif. 90245 makes a variety of Hexfet MOSFET power between a disc rotor having permanent magnets and that of transistors. One should be chosen with a low on resistance, a disc rotor having non-magnetizable high permeability and a rated operating Voltage of at least twice the Voltage material. In the first case, permanent magnets can be made used in the motor. The current rating capacity should be to repel as well as attract simply by changing the direction Several times the normal running current through the device. of current flowing through electromagnet 20. In the Second For example, for an operating voltage of 24 volts, IRFZ48 25 case of Switched-reluctance, attraction is the only net force. would be a good choice. This particular transistor has an on The two transistor circuitry however is advantageous in resistance of 0.018 ohms, a source to drain voltage of 60 driving Such Switched-reluctance motor designs in that ulti Volts, and a continuous current rating of 72 amperes. Proper lization of reverse Voltage Spikes is easily achieved which heat sinking is also recommended. Resistors 86 and 88 also reduces arcing of Switch contacts.

provide voltage dividing to the gate of MOSFET power FIG. 18 shows an electromagnet assembly 20 with an transistor 70. These values should be chosen to properly SPDT Switch 182. Also shown is a common wire 184 and divide the gate Voltage, allow for quick turn on and turn off, two tapped input leads 186 and 188. Lead 188 is thick wire and not drain excessive battery power. In general they wound around the electromagnet core. Output lead 186 is the should be chosen to provide 1 milliampere of Switching tap corresponding to the Second layer of wire to be wrapped current. Resistor 88 also drains the gate capacitance of 35 around the electromagnet core and is of a thinner gauge than MOSFET power transistor 70 when the gate voltage is shut that of the first layer of wire. The output lead from SPDT off by optical sensor 154. This allows for clean Switching.

When mechanical switch 64 is closed, electromagnet 20 electromagnet 20 form a multipleleads switch 182 is 190. Thus output 184 and 190 of tap electromagnet in is controlled by MOSFET switching transistors 70 and 72. conjunction with SPDT switch 182. On motor start up SPDT Light emitting diode 174 is on continuously from Voltage 40 supplied from battery 66 and is controlled by Zener diode 82 Switch entire 182 connects lead 190 to electromagnet lead 186. The length of electromagnet wire is activated. The thin and resistor 80. When a transparent portion of the optical outer layer of wire connected to lead 186 prevents excessive timing disc (not shown) passes by optical timing gate 154, electromagnet currents from demagnetizing permanent mag LED portion 174 transmits its light to photo transistor 176.

Phototransistor 176 turns on and power flows through volt 45 Switch 182 can be switchedspeed net 54. Once a safe rotor has been achieved, SPDT to electromagnet tap 188 thus age dividing resistors 86 and 88. This turns on MOSFET power transistor 70 thereby providing power from batteries shunting the entire length of thin electromagnet wire 186. This will Substantially increase rotor power, Speed, and 66 and 67 through diode 90 and into electromagnet 20. The torque.

interaction of the magnetic field produced by electromagnet

FIG. 19 shows a permanent magnet pair formed of 20 and the magnetic material in the rotor provides propul 50 permanent

Sive force to the edge of the rotor thereby providing 192. Steel piece magnets 54 and 55 Sandwiching a piece of Steel mechanical power. Just before the magnetic material in the 192 forms a flat planar spoke to provide a rotor(not shown) aligns itself in the magnetic field in the Strong mechanical bond between the inner portion of the electromagnet, optical Sensing gate 154 is shut off by an rotor and the periphery where the permanent magnets are opaque region of the optical timing disc (not shown). 55 which located. Also shown is a piece of non-magnetic material 194 MOSFET power transistor 70 is then shut off. Remaining during provides support for permanent magnets 54 and 55 running. Non-magnetic material 194 also provides

Stored magnetic energy in electromagnet 20 then shows up as a reverse voltage spike. Diode 90 isolates MOSFET separation distance from T-shaped steel piece 196 thus power transistor 70 from this spike while diode 92 shunts preventing a short circuit of their magnetic flux. this reverse voltage spike into batteries 68 and 69 giving 60 FIG. 20 shows multiple tap electromagnet 20 interfaced to them a slight charge. AS the magnetic material in the rotor relay 198 for either interlocking of or automatic Switching of passes by its equilibrium position with respect to electro electromagnet taps 182 and 186 based on a Voltage input magnet 20, optical Sensing gate 156 is turned on as a from a generator (not shown) to relay coil 200. Variable transparent portion of the optical timing disc (not shown) resistors 202 and 204 control the activation voltage of relay passes through. Light emitting diode 178 is on continuously 65 198.

from voltage supplied from battery 68 and is controlled by FIG. 21 shows a large diameter disc-shaped rotor 208 Zener diode 98 and resistor 96. Light from light emitting having smooth top and bottom surfaces 134 and 136 respec

Page 32

tively. Also shown are Sections of high permeability non Also shown in the cut away portion of this drawing is rotor magnetizable ferromagnetic material 206 in edge portion 46 electromagnet pole face 312.

of rotor 208. Also shown is shaft 52. FIG. 26 shows a brush timed permanent magnet electric FIG. 22 shows a large diameter disc-shaped rotor 210 motor 362 employing the rotor of FIG. 24. Shaft 322 of this having rough textured top and bottom surfaces 140 and 142. motor is rotatably supported by motor bearings 332 and 334 Located in the periphery of disc 210 are sections of high in end caps 336 and 338. End caps 336 and 338 are mounted permeability non-magnetizable ferromagnetic material 206. to motor casing 340 and support bearings 332 and 334. Also AS usual shaft 52 is used for power output and registration shown are brushes 342, and 346, which are supported by within the motor. brush mounts 358 and 360. Brushes 342 and 346 provide FIG. 23 shows the rotary portion of a brush timed electric power to rotor commutator 304. Centrifugal Switch permanent magnet motor having two separate Sets of elec 306 is also shown which shunts out the thinner outer tromagnet windings 300 and 302. Inner winding set 302 electromagnet windings (not shown) in the rotational portion which is closest to shaft 322, is always connected to com of motor 362 when the RPM value reaches a pre set level. mutator 304 regardless of speed. Because of this, when Also shown is a cut away portion of electric motor 362 power is provided to commutator 304, electromagnet wind 15 showing one of the permanent magnets 358 which is ings 302 will be activated and the motor will run at low mounted against motor casing 340. Also shown in the cut power. Once rotor RPM values reach a safe level that allow away portion of this drawing is rotor electromagnet pole for winding set 300 to be activated without the risk of face 312.

demagnetizing motor permanent magnets (not shown), cen FIG. 27 shows the stationary electromagnet portion 364 trifugal Switch 306 closes thereby connecting Outer windings of a typical brushleSS permanent magnet DC electric motor 300 to commutator 308. At this point, if more motor power having added electromagnet windings which are made from is desired, power may be applied to commutator 308 thereby thicker wire than the first set. Electromagnet casing 340 is increasing the magnetic field of rotor electromagnet pole made from steel and therefore is capable of efficiently faces 310 and 312. Holes 314, 316, 318, and 320 in motor transmitting magnetic flux. Stator electromagnets 366 and shaft 322 are used for routing the leads of electromagnet 25 368 consist of laminated electrical steel to reduce eddy windings 302 under commutator 308 for connection to current losses when the motor is in operation. Stator elec commutator 304. tromagnet 366 has two pole faces 370 and 372. Pole face 370 FIG. 24 shows the rotary portion of a brush timed is attached to motor casing 340. Electromagnet pole face 372 permanent magnet electric motor having two layers of faces inward in a radial direction and is aligned with the electromagnet windings 300, and 301. Layer 300 is the first opposing inward facing electromagnet pole face 374 of layer which is made of wire having a heavier gauge than electromagnet 368. Electromagnet 368 has a second pole layer 301 which is the second layer. Also shown is commu face 376 which is attached to motor casing 340. Both tator 308 which is wired to the start of winding 300 at electromagnets 366, and 368 are wrapped with two layers connection 324. The other end of winding 300 is connected 378, and 380, of electromagnet wire. The first layer of to one side of centrifugal Switch 306 and the start of winding 35 electromagnet wire, layer 378, is of a greater thickness in 301 at connection 326. The other connection 328 to cen cross section than is the wire of second layer 380. Layers trifugal Switch 306 is connected to commutator 308 and the 378 and 380 are both wired in series with a central tap 382 remaining end of electromagnet winding 301. Also shown is which is common to both windings. Wire lead 384 is the shaft 322. When power is applied to commutator 308 by Starting lead made of thick wire for electromagnet windings brushes (not shown) current to electromagnet winding 300 is 40 378 and 380. This lead is the starting lead. Lead 382 is the limited by high resistance electromagnet winding 301. lead at the end of thick electromagnet winding 378. This lead Under these conditions, permanent magnet motorS employ is also the starting of thinner electromagnet winding 380. ing such rotors will run at low power. Once rotor RPM Lead 386 represents the end lead of thinner electromagnet values reach a Safe level whereby shunting of electromagnet winding 380. When power is applied to leads 384, and 386. windings 301 will not result in demagnetization of motor 45 Because the thinner electromagnet wire is in Series with the permanent magnets (not shown), centrifugal Switch 306 thicker wire, the current to the motor is limited to that which closes connection 326 to connection 328 thereby shunting will flow under the applied Voltage through the resistance of electromagnet winding 301. This allows electromagnet both windings in Series. When power is applied acroSS leads winding 300 to be activated with full power. This increases 382 and 384, a significantly greater amount of current flows the magnetic field of rotor electromagnet pole faces 310 and 50 thus increasing the magnetic field between Stator electro 312. magnet pole faces 372, and 374.

FIG. 25 shows a brush timed permanent magnet electric FIG. 28 shows the stationary electromagnet portion 388 motor 330 employing the rotor of FIG. 23. Shaft 322 of this of a typical brushleSS permanent magnet DC electric motor motor is rotatably supported by motor bearings 332 and 334 employing electromagnet windings which are made from in end caps 336 and 338. End caps 336 and 338 are mounted 55 twisting two Strands of electromagnet wire together prior to to motor casing 340 and support bearings 332 and 334. Also winding of stator electromagnets 390 and 392. Electromag shown are brushes 342, 344, 346, and 348, which are net casing 340 is made from steel and therefore is capable of supported by brush mounts 358 and 360. Brushes 342, 344, efficiently transmitting magnetic flux. Stator electromagnets 346, and 348 provide electric power to rotor commutators 390 and 392 consist of laminated electrical steel to reduce 304, and 308. Motor leads 350, 352, 354, and 356 are 60 eddy current losses when the motor is in operation. Stator electrically connected to brushes 342, 344, 346, and 348, electromagnet 390 has two pole faces 394 and 396. Pole face and are used for supplying electric power to motor 330. 25 394 is attached to motor casing 340. Electromagnet pole face Centrifugal switch 306 is also shown which allows commu 396 faces inward in a radial direction and is aligned with the tator 308 to Supply power to extra electromagnet winding opposing inward facing electromagnet pole face 398 of 300 at a preset RPM value. Also shown is a cut away portion 65 electromagnet 392. Electromagnet 392 has a second pole of electric motor 330 showing one of the motor permanent face 400 which is attached to motor casing 340. Both magnets 359 which is mounted against motor casing 340. electromagnets 390, and 392 are wrapped with two twisted

Page 33

strands 402, and 404, of electromagnet wire. Electromagnet 564, and 568 are wired to the transistor amplification cir wire strands 402, and 404, are electrically connected to each cuitry shown in FIG. 17 of the original application. Also other at lead 406. The two twisted Strands of wire are then wired to this circuitry of course are motor power input leads wound around both electromagnet cores thus forming elec 382,384, and 386.

tromagnets 390, and 392. The two ends 408, and 410 of the FIG. 32 shows the rotary portion 570, of a large diameter twisted Strand are kept electrically isolated from one another. brushless DC electric motor consisting of a central turbofan When electric power is applied across lead 406 and either portion 572, and permanent magnets 574 around the inside lead 408 or lead 410, the current to the motor is limited to that which will flow under the applied voltage through the periphery of rotary portion 570. Also shown is motor shaft resistance of a single strand of wire. When leads 408 and 410 576 which is fixedly mounted to the center of turbofan are electrically connected together, both Strands of wire are portion their 572. Permanent magnets 574 are mounted having pole faces facing inward in a radial direction, and now connected in parallel. The amount of current that will oppositely polarized flow through the electromagnet windings is effectively net. The opposite polewith each Successive permanent mag doubled. Under these conditions, an increase in the magnetic facing the inner portion 578 ofofthe faces each permanent magnet are periphery portion of rotor field between stator electromagnet pole faces 396, and 398 15 570. The periphery portion of rotor 570 is made from a is the result.

FIG. 29 shows the stationary electromagnet portion 432 permanent magnets 574 and concentratemagnetically ferromagnetic material Such as Steel to their flux connect inward in of a typical brushleSS DC permanent magnet electric motor a radial direction.

employing two isolated Sets of electromagnet windings on

Stator electromagnets 420 and 422. Electromagnet casing FIG. 33 shows a large diameter brushless DC electric motor 340 is made of steel and therefore is capable of efficiently a centrally 592, consisting of the rotary portion of FIG. 32, and transmitting magnetic flux. Stator electromagnets 420 and located Star shaped electromagnet 580. Bearing 588 rotatably 422 consist of laminated electrical Steel to reduce eddy plate 586 is fixedly connects end plate 586 to motor shaft. End current losses when the motor is in operation. Stator elec shaped electromagnetmounted 580.

into the central portion of star

Mounting holes 590 are used to tromagnet 420 has two pole faces 424, and 426. Pole face 25 mount the motor to a Suitable piece of equipment 426 is attached to motor casing 340. Electromagnet pole face frame of an automobile, or Some piece of highSuch as the powered 424 faces inward in a radial direction and is aligned with the industrial equipment. Power input leads 582 and 584 pro opposing inward facing electromagnet pole face 428 of vide power to star shaped electromagnet 580 through a electromagnet 422. Electromagnet 422 has a Second pole face 430 which is attached to motor casing 340. Both transistor illustrated amplification circuit (not shown) Such as the one in FIG. 17 in the original patent application. The electromagnets are wound with two Separate Sets of wind ings. Electromagnet 420 is wound with a first set of wind motor is timed with position sensing circuitry (not shown) such as the photocell gate assembly outlined in FIG. 15 in ingS 434, and a Second Set of windingS 436. Electromagnet the original patent application. 422 is wound with a first set of electromagnet windings 438, and a second set 440. Electromagnet windings 434, and 438 35 FIG. 34 shows a large diameter brushless DC electric are connected together in Series and end at leads 412, and motor 592 having a rotary portion consisting of a central 414. Electromagnet windings 436, and 440 are connected turbofan and permanent magnets around the periphery, a together in Series and end at leads 416, and 418. Applying centrally located Star shaped electromagnet, and added gear electric power to either Set of leads results in a magnetic field teeth 594 around the outside periphery. in electromagnets 420, and 422 that will not be sufficient to 40 FIG. 35 shows a large diameter brushless DC electric demagnetize rotor permanent magnets (not shown) under motor 592 having a rotary portion consisting of a central motor stall conditions. When it is desirable to increase the turbofan and permanent magnets around the periphery, a field strength of electromagnets 420, and 422 power is centrally located Star shaped electromagnet, and teeth 596 appropriately applied to both Sets of leads. for engagement to a cog belt around the outside periphery. FIG. 30 shows the rotary portion of a typical DC brushless 45 FIG. 36 shows a large diameter air cooled electric motor electric motor. Rotary portion 442 consists of a shaft 322 592 of this invention employed in a vehicle hub drive system attached to permanent magnets 444, and 446. Permanent having a Steel rim 598, permanent magnets attached to the magnets 444, and 446 have their direction of magnetization inside portion, a Star shaped electromagnet assembly 580, such that exposed face 448 of permanent magnet 446 is which is bolted onto the vehicle frame (not shown), and north and points outward in a radial direction, and exposed 50 large Structural air moving Spokes 600 for connecting the face 450 of permanent magnet 444 is south and points outer rim portion 598 to axle assembly 576.

outward in a radial direction as well. FIG. 37 shows the rotary portion 602 of a large diameter FIG. 31 shows a brushless DC electric motor of this brushless DC motor consisting of a planar disc 604 having invention having the front end cap removed to expose the permanent magnets 606 about the periphery in a radial inner workings. Rotor 442 of FIG. 30 is shown inside of 55 direction, and fixed air moving vanes 608 protruding from multi-tap electromagnet assembly 364 of FIG. 27. Also the edge. In this particular large diameter rotor, permanent shown is end cap 338 and small electric generator 452. magnets 606 have a direction of magnetization which is in Small electric generator puts out a Voltage which is propor a radial direction with each Successive permanent magnet tional to motor RPM values and is used as part of the being oppositely polarized. Fixed air moving vanes 608 are interlocking circuitry of this invention. 60 on the top surface of planar disc 604 and move air from top Power output leads 554, and 556 of Small electric gen to bottom of the electromagnets (not shown).

erator 452 are wired to a relay such as relay 200 of FIG. 20 FIG. 38 shows a large diameter brushless motor 610 in the original application. Also shown is the photocell gate consisting of a planar disc rotor 602 having permanent casing 558 which houses the photocell gate circuitry for magnets 606 about the periphery in a radial direction, Sensing rotor position. A detailed diagram of the photocell 65 electromagnets 614 pointing inward toward the edge of the gate and light control disc are shown in FIG. 15 of the disc, and fixed air moving vanes 608 protruding from the original application. Photocell gate sensor leads 560, 562, edge of the disc which move air over electromagnets 614.

Page 34

Also included is electromagnet mounting plate 616 along position of Said plurality of electromagnets to cause with bearings 618 and 620 which rotatably connect mount Said rotatable portion to rotate; ing brackets 622, and 624 to motor shaft 626. Mounting each of Said plurality of electromagnets including a wind brackets 622, and 624 are firmly fastened to mounting plate ing;

616. Electric power is applied to leads 628, and 630 from the Said winding of at least one of Said electromagnets having transistor amplification circuit of FIG. 17 in the original a configuration that demagnetizes Said permanent mag patent application (not shown). AS usual, Timing is provided nets at Stall conditions, and by the photo-optic position Sensing apparatus of FIG. 15 in electrical interlocking circuitry for allowing Said configu the original application (not shown). ration of Said winding of Said at least one of Said FIG. 39 shows the rotary portion 630 of a large diameter electromagnets to be activated when Said Shaft reaches brushless DC electric motor consisting of a central turbofan a preset Speed that reduces current in Said windings to portion 632, motor shaft 634, and non-magnetizable high a level Sufficient to prevent demagnetization of Said permeability material 638 mounted to inside surface 636 in permanent magnets.

the periphery portion of rotary portion 630 as well as 2. A motor as claimed in claim 1 wherein Said motor is a

mounting hardware 686, 688, and 690 of FIG. 33. Also brushless motor.

employed is electromagnet 580 which is shown in FIG. 33. 3. A direct current (DC) permanent magnet electric motor Electromagnet timing is carried out using the photocell gate comprising:

shown in FIG. 15 of the original patent application. Ampli a Stationary portion including at least one electromagnet fication of the timing Signal from the photocell gate is having at least one winding and poles when Said carried out using the electrical circuitry shown in FIG. 17 of winding is electrically energized; the original patent application.

FIG. 40 shows the rotary portion 640 of a large diameter a rotatable portion including:

brushless DC electric motor consisting of a planar disc 642 a shaft rotatable with respect to Said Stationary portion; having non-magnetizable high permeability material 644 25 at least one disc mounted to Said shaft, Said disc having embedded on the outside periphery, along with added air a radial plane including an annular portion rotatably moving Surfaces 608. Also employed are electromagnets disposed within Said Stationary portion; and 614 of FIG.38, as well as mounting hardware 616, 618, 620, a plurality of permanent magnets each having a direc 622, 624, and 626 of FIG. 38. As usual, electromagnet tion of magnetization and poles, Said plurality of timing is carried out using the photocell gate shown in FIG. permanent magnets being disposed on Said annular 15 of the original patent application. Amplification of the portion of Said disc So that the direction of magne timing Signal from the photocell gate is carried out using the tization thereof is transverse through said disc and So electrical circuitry shown in FIG. 17 of the original patent that the poles thereof are aligned in coupling proX application. imity to the poles of Said electromagnets, Those skilled in the art will understand that the embodi 35 position circuitry for Sensing a position of Said plurality of ments of the present invention described above exemplify permanent magnets with respect to Said plurality of the present invention and do not limit the Scope of the electromagnets and for providing a signal based on Said invention to these specifically illustrated and described position to Said at least one of Said electromagnets to embodiments. The scope of the invention is determined by cause Said rotatable portion to rotate; the terms of the appended claims and their legal equivalents, 40 each of Said at least one of Said electromagnets having rather than by the described examples. In addition, the poles facing perpendicular to Said radial plane of Said exemplary embodiments provide a foundation from which annular portion of Said disc; numerous alternatives and modifications may be made, Said winding of at least one of Said electromagnets having which alternatives and modifications are also within the a configuration that demagnetizes Said permanent mag Scope of the present invention as defined in the appended 45 nets at Stall conditions, and claims. electrical interlocking circuitry for allowing Said configu What is claimed is: ration of at least one of Said electromagnets to be 1. A direct current (DC) permanent magnet electric motor activated when Said Shaft reaches a preset Speed that comprising: reduces current in Said windings to a level Sufficient to a Stationary portion including a plurality of C-shaped 50 prevent demagnetization of Said permanent magnets. electromagnets disposed to define an inner annular 4. A motor as claimed in claim 3 wherein Said motor is a channel, each of Said electromagnets having poles, brushless motor.

a rotatable portion including: 5. A direct current (DC) permanent magnet electric motor a shaft rotatable with respect to Said Stationary portion; comprising:

at least one disc mounted to Said shaft, Said disc having 55 a Stationary portion including a plurality of electromag an annular portion rotatably disposed within Said nets facing outward in a radial direction, each of Said inner annular channel of Said Stationary portion; and electromagnets having poles when electrically ener a plurality of permanent magnets each having a direc gized;

tion of magnetization and poles, Said plurality of a rotatable portion including:

permanent magnets disposed on Said annular portion 60 a shaft rotatable with respect to Said Stationary portion; of Said disc So that the direction of magnetization a housing fixedly attached to one end of Said Shaft and thereof is transverse through Said disc and So that the circumscribing Said Shaft, Said housing having an poles thereof are aligned in coupling proximity to the inner Surface and an outer Surface; and poles of Said electromagnets, a plurality of permanent magnets each attached to Said position circuitry for Sensing a position of Said plurality of 65 inner Surface portion of Said housing and having a permanent magnets with respect to Said plurality of Said pole, Said poles of Said permanent magnets facing electromagnets and for providing a signal based on Said inward in a radial direction and alternating with each

Page 35

Successive of Said permanent magnets and So that the a Stationary portion including:

poles thereof are aligned in coupling proximity to the a housing for rotatably Supporting Said shaft and having poles of Said electromagnets, an inner Surface; and position circuitry for Sensing a position of Said plurality of a plurality of electromagnets each attached to Said inner permanent magnets with respect to Said plurality of Said 5 Surface of Said housing, having a direction of mag electromagnets and for providing a signal based on Said netization and poles when electrically energized, and position of Said plurality of electromagnets to cause including a winding;

Said rotatable portion to rotate; Said poles of Said electromagnets facing inward in a each of Said plurality of electromagnets including a radial direction and alternating with each Successive winding, said winding of at least one of Said electro of Said electromagnets, and magnets having a configuration that demagnetizes Said Said winding of at least one of Said electromagnets permanent magnets at Stall conditions, and having a configuration that demagnetizes Said per electrical interlocking circuitry for allowing Said configu manent magnets at Stall conditions, ration of Said winding of Said at least one of Said 15 electrical interlocking circuitry for allowing Said configu electromagnets to be activated when Said Shaft reaches ration of Said winding of Said at least one of Said a preset Speed that reduces current in Said winding to a electromagnets to be activated when Said Shaft reaches level Sufficient to prevent demagnetization of Said a preset Speed that reduces current in Said winding to a permanent magnets. level Sufficient to prevent demagnetization of Said 6. A motor as claimed in claim 5 further comprising permanent magnets, and current-limiting circuitry for protecting Said permanent magnets from demagnetization. position circuitry for Sensing a position of Said plurality of 7. A motor as claimed in claim 5 wherein said motor is a permanent magnets with respect to Said plurality of brushless motor. electromagnets to cause Said rotatable portion to rotate. 8. A motor as claimed in claim 5 further comprising a 25 13. A motor as claimed in claim 12 wherein Said perma turbofan fixedly attached on one end of Said housing. nent magnets are further protected from demagnetization by 9. A motor as claimed in claim 5 wherein said outer the addition of current limiting circuitry. Surface of Said housing includes gear teeth. 14. A motor as claimed in claim 12 wherein Said motor is 10. A motor as claimed in claim 5 wherein said outer a brushleSS motor.

Surface of Said housing includes teeth for engagement to a 15. A motor as claimed in claim 12 wherein said electrical cog belt. interlocking circuitry is fixedly attached to Said motor. 11. A motor as claimed in claim 5 wherein said outer 16. A motor as claimed in claim 12 wherein each Said Surface of Said housing includes a means for mounting a winding includes two or more twisted wire Strands. vehicle tire. 17. A motor as claimed in claim 12 wherein each said 12. A permanent magnet electric motor comprising; winding includes a first layer of electromagnet wire con

rotatable portion including: nected to a first motor tap and a Second layer of wire a shaft; and connected to a Second motor tap, Said wire of Said first layer a plurality of permanent magnets each attached to Said having a thickness greater than Said wire of Said Second shaft and having a direction of magnetization and layer.

poles, 40 18. A motor as claimed in claim 12 wherein Said windings Said poles of Said permanent magnets facing outward in are electrically isolated from each other. a radial direction and alternating with each Succes

Sive of Said permanent magnets,