Rotor for a rotating electric machine

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ROTOR FOR A ROTATING ELECTRIC another problem exists, in that high-frequency impact mag MACHINE netic noise caused by metallic collision noise is made between the claw-like magnetic poles and the non-magnetic

This is a continuation-in-part of application Ser. No. holding member due to the vibration conveyed from the 08/571,217, filed on Dec. 12, 1995, which was abandoned 5 Lundell-type pole cores when the Lundell-type pole cores upon the filing hereof and which was a division of applica are rotated by rotation of the shaft.

tion Ser. No. 08/297.838 filed Aug. 30, 1994, now U.S. Pat. Furthermore, in the technique disclosed in Japanese No. 5.483.116 issued Jan. 9, 1996. Unexamined Patent Publication 3-265450, as the non magnetic ring is formed to have a circular shape with a

BACKGROUND OF THE INVENTION 10 constant width, strains are generated which deform the

1. Field of the Invention non-magnetic ring radially inwardly when a difference in thermal expansion exists between the non-magnetic ring and

The present invention generally relates to a rotor for a the claw-like magnetic poles. The non-magnetic ring is often rotating electric machine, such as alternating current (a.c.) deformed or broken.

generators and electric motors. More particularly, the 15 present invention relates to rotary electric machines, which SUMMARY OF THE INVENTION are adapted to hold permanent magnets with a resin-made It is an object of the present invention to provide a rotor magnet holding member, where the permanent magnets are for a rotating electric machine which can prevent perfor disposed between circumferential side faces of two adjacent mance degradation by preventing an air gap from expand claw-like magnetic poles of Lundell-type pole cores, for Ilg.

instance.

2. Related Art

It is also an object of the present invention to achieve low noise operation by preventing the generation of high

In a conventional rotor for an a.c. generator, for example, frequency impact magnetic noise.

it is known that each permanent magnet in the generator is It is another object of the present invention to provide a inserted between the circumferential side faces of two 25 rotor of a rotating electric machine which can stably hold adjacent claw-like magnetic poles of Lundell-type pole permanent magnets by absorbing and relieving strains cores to diminish the magnetic flux leakage between a applied to the magnet holding member and at the same time plurality of claw-like magnetic poles. At the same time, the prevent the deformation and breakage of the magnet holding magnetic flux of the permanent magnets is directed towards member, the field coil (field winding) to improve the output efficiency, 30 In the present invention, pole cores having a plurality of i.e., the electric power generating efficiency of the stator coil claw-like magnetic poles formed on the outer periphery (armature winding) against the magnetomotive force of the thereof are used. The pole cores are assembled so that the field coil. claw-like magnetic poles engage with each other and rotate When Lundell-type pole cores rotate, strains are gener 35 integrally with a rotatable shaft. The present invention ated on the permanent magnets in the direction of the further includes a plurality of permanent magnets, each of centrifugal force. Therefore, conventional devices require an which is disposed between two adjacent claw-like magnetic arrangement where the permanent magnets do not protrude poles of the pole cores and magnetized in the direction so as from the area between the circumferential side faces of two to diminish the magnetic flux leakage between the claw-like adjacent claw-like magnetic poles. magnet poles. Also, the present invention includes a resin Such a technique is disclosed in, for example, Japanese made holding member fit between the circumferential side Unexamined Patent Publication No. 4-165950. This docu faces of the two adjacent claw-like magnetic poles to hold ment teaches that the outer face of a rotor, i.e., the outer the permanent magnets. The resin-made magnet holding peripheral face of a plurality of claw-like magnetic poles of member is formed in a ring shape that circuitously com Lundell-type pole cores, and the outer faces of permanent 45 pletes a 360° circle.

magnets, are covered with a non-magnetic holding member Furthermore, the present invention may be formed such made of a metal such as aluminum. Furthermore, another that the resin-made magnet holding member has a plurality technique is disclosed in Japanese Unexamined Patent Pub of encompassing parts for encompassing or covering and lication No. 3-265450. This document discloses that a metal holding each of the permanent magnets. Further, connecting or resin-made non-magnetic ring is disposed between claw SO parts interconnect the encompassing parts. The permanent like magnetic poles of Lundell-type pole cores so that the magnets may be buried in the resin-made magnet holding permanent magnets are held by the non-magnetic ring. member.

According to the technique disclosed in Japanese Unex In this arrangement, because the plurality of permanent amined Patent Publication No. 4-165950, which employs a magnets are buried in the resin-made magnet holding construction where the outer peripheral face of a rotor is 55 member, it is possible to prevent foreign matter from reach covered with a non-magnetic holding member, a problem ing the magnets, and the formation of cracks on the surfaces exists in that the air gap expands between the outer periph of the permanent magnets can be avoided. Moreover, even eral faces of the Lundell-type pole cores and the internal if cracks were to occur on the permanent magnets, it is peripheral face of the stator core. Thus, the output efficiency, possible to prevent the permanent magnets from flying off i.e., the electric power generating efficiency of the stator the rotary device since they are covered with resinous coil, is degraded by the expanding air gap between the outer material. Furthermore, the thermal impact due to the severe peripheral faces of the Lundell-type pole cores and the cooling?heating cycles experienced by a rotating electric internal peripheral face of the stator core. machine as well as small vibrations caused by rotation can Furthermore, the metal-made non-magnetic holding be eliminated.

member and the permanent magnets are mounted on the 65 The present invention may also be formed so that the Lundell-type pole cores. which are subjected to the magne resin-made magnet holding member is molded with resin in tomotive force produced by the field coil. Accordingly, such a manner that only part of the permanent magnet is

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buried therein. When a plurality of permanent magnets are member fit between the side faces of each of two adjacent buried in the molded resin, the permanent magnets can be claw-like magnet poles of Lundell-type pole cores, the gap held using the exposed parts. thus making the positioning of between the outer peripheral face of the rotor and the inner the magnets quite easy to accomplish, peripheral face of the stator, i.e. the air gap, does not Furthermore, where the resin-made magnet holding mem 5 expand, whereby the degradation in the performance of the ber is formed of resin magnetic material, the magnetic flux rotating electric machine is prevented. Moreover, by sup of the permanent magnets can be reinforced if the resin pressing vibrations conveyed from the pole cores to the made magnet holding member is magnetized in the same permanent magnets to prevent the interference between the direction as the permanent magnets. magnet holding member and the permanent magnets, the The present invention may also be formed so that the 10 generation of high-frequency impact magnetic noise is also resin-made magnet holding member has board parts, which suppressed. Furthermore, as the resin-made magnet holding contact the inner faces of the permanent magnets, base parts member is formed in a zig-zag ring shape or in repeated for controlling the axial movement of the permanent V-shaped turns, the elastic deforming force is generated on magnets, and catching parts for controlling the radial move the whole portion of the resin-made magnet holding member ment of the permanent magnets. Also, the resin-made mag net holding member holds each of the permanent magnets in 15 to absorb and relieve strains applied to the magnet holding a state where the opposed faces facing the side faces of the member.

claw-like magnetic poles are open and the side faces of the BRIEF DESCRIPTION OF THE DRAWINGS permanent magnets contact the side faces of the claw-like Other objects, features and characteristics of the present magnetic poles. invention along with methods of operation and the functions In this arrangement, the assembly of the permanent mag of interrelated parts will become apparent to a person skilled nets to the resin-made magnet holding member can be easily in the art to which the invention pertains from a study of the performed. As the assembly is performed, the magnetic flux following detailed description, the appended claims, and the can be easily passed through the claw-like magnetic poles by attached figures, all of which form a part of this specifica having the permanent magnets contact the side faces of the 25 tion. In the figures:

claw-like magnetic poles. FIG. 1 is a sectional view of the main part of the The present invention may also include a plurality of alternating current generator for a vehicle according to a first claw-like magnetic poles that are provided with a flange or embodiment of the present invention; taper shaped catching parts for suppressing the centrifugal FIG. 2 is a perspective side view of the rotor of the movement of the resin-made magnet holding member. The alternating current generator illustrated in FIG. 1; size of the catching parts is set so that the centrifugal force FIG. 3 is a sectional view of the main part of the rotor of of the permanent magnets compresses the resin-made mag the alternating current generator illustrated in FIG. 1; net holding member on the catching parts. The suppression FIG. 4 is a perspective side view illustrating the state in of the permanent magnets and the resin-made holding mem ber in the centrifugal direction can be performed with 35 which sixteen permanent magnets and a magnet holder are assembled;

greater precision, and thus resistance to the centrifugal forces acting on the permanent magnets and holding mem FIG. 5 is a perspective side view of a magnet holder; ber can be improved. FIG. 6 is a sectional view of the main part of the The rotating electric machine may be an alternating alternating current generator for a vehicle employed accord current generator. The rotor may have Lundell-type pole ing to a second embodiment of the present invention; cores, which allow the resin-made magnet holding member FIG. 7 is a perspective side view of the rotor of the holding the permanent magnets to intervene suitably, and the alternating current generator illustrated in FIG. 6; power generating efficiency can be improved by the perma FIG. 8 is a sectional view of the main part of the rotor of nent magnets. the alternating current generator illustrated in FIG. 6; The resin-made magnet holding member does not have to 45 FIG. 9 is a perspective side view of the main part of the have both ends thereof interconnected even though it is rotor of the alternating current generator illustrated in FIG. formed in a circular manner, thus allowing for size differ 8:

ences between the permanent magnets and the resin-made FIG. 10 is a perspective side view of a magnet holder with magnet holding member to be easily absorbed. That is, the which sixteen permanent magnets are molded; resin-made holding member may be formed to have a 50 FIG. 11 is a sectional view of the main part of the rotor discontinuity therein. of the alternating current generator for a vehicle according It is also possible for the present invention to include pole to a third embodiment of the present invention; cores having a plurality of claw-like magnetic poles formed FIG. 12 is a magnified view of the main part of the magnet on the outer periphery thereof, which are assembled so that holder illustrating the modification where part of the per the claw-like magnetic poles engage with each other and 55 manent magnet is exposed;

rotate integrally with a rotatable shaft. The present invention FIG. 13 is a perspective side view illustrating the modi may also have a plurality of permanent magnets each of fication where a part of the magnet holder is formed so as to which is disposed between two adjacent claw-like magnetic be discontinuous; and poles of the pole cores and magnetized in the direction that FIG. 14 is a perspective view of a magnet holder accord diminishes the magnetic flux leakage between the claw-like ing to a fourth embodiment of the present invention. magnet poles. Further, a resin-made holding member may be fit between side faces of the two adjacent claw-like magnetic DETALED DESCRIPTION OF THE poles to hold the permanent magnets. The resin-made mag PRESENTLY PREFERRED EXEMPLARY net holding member is preferably formed so that it zig-zags EMBOOMENTS in a complete circle, making repeated V-shaped turns. The rotor of a rotating electric machine according to the According to the present invention, as a plurality of present invention will now be described with reference to permanent magnets are held by a resin-made magnet holding the attached figures.

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FIGS. 1 through 5 illustrate the first embodiment of the 16, respectively. The inner face of each permanent magnet present invention. FIG. 1 illustrates the main part of an 11, which faces shaft 6, and both axial end faces of each alternating current generator for a vehicle, while FIGS. 2 permanent magnet 11 are held by magnet holder 12, while and 3 illustrate a rotor of an alternating current generator, as the outer face of each permanent magnet 11 faces the inner a rotating electric machine. peripheral face of stator 2 across an air gap G. The perma Alternating current generator 1 mainly comprises stator 2, nent magnet according to the first embodiment has a which serves as the armature, and a rotor 3 serving as the rectangular, box-like shape with a radial length of 10 mm, an field. Stator 2 is composed of stator core 4 and stator coils axial length of 26 mm and a width of 8 mm. 5, which are supported by a frame (not illustrated). Stator FIG. 5 illustrates magnet holder 12. Magnet holder 12 is core 4 is formed of overlapping thin sheet steel. A multi O a resin-made holding member and is singly molded in one plicity of slots (not illustrated) are provided on the internal peripheral face of stator core 4, and three pairs of stator coils piece using non-magnetic resin material, such as poly 5 are inserted in the slots. Alternating voltage is generated on butylene-terephthalate contains 40% glass resin (PBT resin) and nylon 66 which fibers.

stator coils 5 when rotor 3 rotates.

Rotor 3 rotates integrally with shaft 6 and mainly com Magnet holder 12 has sixteen board parts 24 extending prises Lundell-type pole cores 7, field coil 8, slip rings 9 and 15 generally axially, each of which holds one of permanent 10, sixteen permanent magnets 11, and magnet holder 12. magnets 11 in the state that the end faces of each permanent Shaft 6 is connected to a pulley (not illustrated) and is magnet 11 contact two adjacent claw-like magnetic poles 15 rotatably driven by an engine (not illustrated) mounted in a and 16. Connecting parts 25 interconnect boards 24. Con vehicle. Ring-shaped stopper 6a is integrally formed on 20 necting parts 25 extending generally circumferentially are shaft 6 to fix Lundell-type pole cores 7 to the outer periphery disposed so as to relieve strains by providing the entire of shaft 6. magnet holder 12 with anti-expansion rigidity while ensur Lundell-type pole cores 7 comprise circular plate parts 13 ing some degree of elasticity and at the same time facilitat and 14 assembled to shaft 6 and eight claw-like magnetic ing assembly. Here, the inner peripheral faces of connecting poles 15 and 16 extending from the outer peripheral side of 25 parts 25 are formed so as to have a generally circular shape. circular plate parts 13 and 14 so that claw-like magnetic Sixteen board parts 24, each of which is fit between the poles 15 and 16 engage with one another. It is noted that, in side faces of two adjacent claw-like magnetic poles 15 and Lundell-type pole cores 7 when an electric current flows 16, are formed to have a zig-zag ring shape, which zig-zags through field coil 8, all of claw-like magnetic poles 15 back and forth between poles 15 and 16 with repeated disposed on one axial side are magnetized to the south (S) 30 V-shaped turns formed at base parts 26 and 27 (described pole while all of claw-like magnetic poles 16 disposed on the below). On the upper end face (the face on the side opposite other axial side turn toward the north (N) pole. In the middle shaft 6) of each of board parts 24, permanent magnets 11 are part of Lundell-type pole cores 7, wound parts 18 and 19 are individually placed so that the inner face of each permanent formed on which field coil 8 is wound a plurality of times magnet 11 contacts the upper end face respectively. around resin-made bobbin 17. 35 A pair of base parts 26 and 27 extend radially outward In the circumferential direction of claw-like magnetic towards stator 2 and are formed from return point parts 28 poles 15 and 16, flange parts 20 through 23 (depicted in FIG. and 29 of board parts 24. That is, the base parts 26 and 27 3) are formed in order to prevent permanent magnets 11 extend radially from both axial ends of board parts 24. Here, from protruding in the centrifugal direction. Flange parts 20 the inner peripheral faces of the board parts 24 are formed through 23 act as stopping parts and catch and prevent the to have a slightly circular arcuate shape. outer peripheral faces of permanent magnets 11 from mov Permanent magnets 11 are fit between base parts 26 and ing when rotor 3 turns. 27 so that the outer face and both side faces of each The first end and last end of field coil 8 are connected to permanent magnet 11 are exposed. A pair of base parts 26 slip rings 9 and 10 via lead wires 8a and 8b. Here, field coil and 27 contact opposite end faces of each permanent magnet 8 has been impregnated with an epoxy base resin injected 45 11 so as to suppress the axial movement of each permanent from trough 23a formed between the outer peripheral part of magnet 11. Base parts 26 and 27 include catching parts 32 circular plate part 13 and the bottom part of claw-like through 35 extending axially, which suppress the axial magnetic pole 15. The impregnation is conducted to prevent movement of each permanent magnet 11.

the displacement of field coil 8 and also to prevent noise Two adjacent board parts 24 meet one another in generally generation. a V-shape at base parts 26 and 27. Triangular partition Slip rings 9 and 10 are mounted on one end of shaft 6 to boards 36 protrude axially from connecting parts 25, and supply an exciting current to rotating field coil 8. The device thus maintain a separation between board parts 24. Catching is designed so that on the periphery of slip rings 9 and 10, parts 32 and 33 of each base part 26 extend in a generally a brush (not illustrated) is provided that slides in order to V-shape so that the outer end of base part 26 contacts the Supply an exciting current. outer end face of permanent magnet 11. Rectangular slit 38 FIG. 4 illustrates the state where sixteen permanent mag at which the claw-like end of each magnetic pole is disposed nets 11 are assembled with magnet holder 12. Each of the is provided between catching parts 32 and 33 so as to make sixteen permanent magnets is disposed between the circum it possible to disassemble magnets 11 from the tip of ferential side faces of two adjacent claw-like magnetic poles claw-like magnet pole 16 without consuming a great deal of 15 and 16 and magnetized in the direction that diminishes time or effort.

the magnetic flux leakage between the two adjacent claw Catching parts 34 and 35 of each base part 27 extend in like magnetic poles 15 and 16. Ferrite magnets, resin mag a generally V-shape so that the outer end of base part 27 nets formed by sintering the powder of nylon, Nd, Fe and B, contacts the outer end face of permanent magnet 11. That is, rare earth magnets, or the like, are used as permanent catching parts 34 and 35 face catching parts 32 and 33. magnets 11. 65 Rectangular slit 39 is provided between catching parts 34 Both side faces of each permanent magnet 11 contact the and 35 so as to make it possible to disassemble magnets 11 side faces of two adjacent claw-like magnetic poles 15 and from the tip of claw-like magnet pole 15.

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The inner peripheral faces of catching parts 32 through 35 16. Furthermore, as the magnet holder 12 is molded in one are formed so as to be thinner proximate the tip thereof, and piece with resin, vibrations caused between the magnet the outer peripheral faces of catching parts 32 through 35 are holder 12 and the permanent magnets 11 can be successfully formed so that they have a generally circular arcuate shape. suppressed, while at the same time preventing high The method of assembling rotor 3 according to the first frequency impact magnetic noise.

embodiment will be described with reference to FIGS. 1 When an exciting current flows through field coil 8, a through 5. magnetomotive force is generated in the field coil 8. At this First, resin-made magnet holder 12, shown in FIG. 5, is time, claw-like magnetic pole 15 on one axial side is formed by means of undercutting using an one-way cutting O magnetized to the south (S) pole, and claw-like magnetic molding die (not illustrated). Each of permanent magnets 11 pole 16 on the other side is magnetized to the north (N) pole. is then fit between each pair of base parts 26 and 27 of Then, due to the existence and location of permanent mag magnet holder 12 to form an assembly such as the one nets 11, the magnetic flux leakage between claw-like mag pictured in FIG. 4. netic pole 15 on one side and claw-like magnetic pole 16 on By firmly fitting each of permanent magnets 11 between the other side is diminished, and alternating current voltage catching parts 32 through 35, as illustrated in FIG. 4, 15 isgeneratedgenerated at stator coils 5 by adding the magnetic flux by permanent magnets 11 themselves to the permanent magnets 11 and magnet holder 12 are assembled.

This manner of assembly allows permanent magnets 11 and magnetic flux acting on stator core 4.

magnet holder 12 to be put easily together in a short period Moreover, as magnet holder 12 is formed to have a of time. zig-zag circuitous ring shape, which completes 360°. it is Field coil 8 is then wound a plurality of times on the outer possible expansion to provide entire magnet holder 12 with anti rigidity while ensuring some degree of elasticity, periphery of resin-made bobbin 17. Then, circular plate 13, whereby strains can be relieved and assembly is performed disposed on one side, field coil 8, permanent magnets 11 on easily.

the magnet holder 12, and circular plate 14 on the other side of plate 13 are assembled. At this time, as illustrated in 25 designedAs described above, as alternating current generator 1 is FIGS. 2 and 3, the device is structured so that each of to prevent permanent magnets 11 from protruding permanent magnets 11 is disposed between claw-like mag from the area between the side faces of claw-like magnetic netic poles 15 and 16. Permanent magnets 11 are caught by poles 15 and 16, the magnetic flux leakage between adjacent flange parts 20 through 23 of the claw-like magnetic poles claw-like magnetic pole 15 and claw-like magnetic pole 16 15 and 16. Then, after shaft 6 is inserted in the core, slip 30 can be prevented. Furthermore, as permanent magnet 11 is rings 9 and 10 are mounted on the outer periphery of shaft held by magnet holder 12 so that both circumferential side 6 for manufacturing rotor 3. faces of permanent magnet 11 directly contact the side faces Here, as illustrated in FIGS. 1 and 2, the outer diameter of claw-like magnetic poles 15 and 16, the magnetic flux of of the outer peripheral face of catching parts 32 through 35 permanent magnets 11 can be further improved. of magnet holder 12 is larger than the outer diameter of the 35 Moreover, as magnet holder 12 is molded in a unitary outer peripheral face of permanent magnets 11. Furthermore, piece from resin, collisions between permanent magnets 11 the outer diameter of the outer peripheral faces of claw-like and magnet holder 12 caused by the vibration of Lundell magnetic poles 15 and 16 is larger than the outer diameter type pole cores 7 can be cushioned, thus successfully of the outer peripheral face of catching parts 32 through 35 preventing the generation of high-frequency impact mag of magnet holder 12. That is, as permanent magnets 11 and netic noise.

magnet holder 12 do not protrude from the outer peripheral Furthermore, as magnet holder 12 is formed in a substan face of Lundell-type pole cores 7, the expansion of air gap tially circular zig-zag ring shape, it is possible to provide the G formed between the outer peripheral face of Lundell-type entire magnet holder 12 with anti-expansion rigidity while pole cores 7 and the inner peripheral face of stator core 4 can ensuring some degree of elasticity. Thus, strains caused by be prevented. 45 a difference in thermal expansion can be relieved and Operation of an alternating current generator for a vehicle assembly of the device can be performed easily. according to the first embodiment will be described with In addition, as permanent magnets 11 and magnet holder reference to FIGS. 1 through 5. 12 do not protrude from the outer diameter of Lundell-type When shaft 6 is rotatably driven by the engine, rotor 3 pole cores 7, the expansion of air gap G formed between the rotates integrally with shaft 6. Accordingly, permanent mag outer peripheral face of Lundell-type pole cores 7 and the nets 11, each disposed within magnet holder 12 circumfer inner peripheral face of stator core 4 can be prevented. entially between adjacent claw-like magnetic pole 15 on one Accordingly, the output efficiency, i.e., the generating effi side of each of permanent magnets 11 and claw-like mag ciency of stator coils 5, is improved against the magneto netic pole 16 on the other side, also rotate. Hence, strains are motive force of field coil 8 of alternating current generator applied on permanent magnets 11 in the direction of the 55 1.

centrifugal force, whereby forces are generated in the radial In this embodiment, an additional quantity of magnetic direction which can move permanent magnets 11. flux can be obtained, as compared to a rotor simply using As each of permanent magnets 11 are fit between a pair of twelve-pole pole cores and twelve permanent magnets, base parts 26 and 27 of magnet holder 12, and as both ends because the present embodiment uses rotor 3 having sixteen of the outer face of each of the permanent magnets 11 are pole Lundell-type pole cores 7 and sixteen permanent mag caught by catching parts 32 through 35, respectively, per nets 11. This is due to the fact that sixteen-pole Lundell-type manent magnets 11 are firmly held by magnet holder 12. The pole cores 7 have a larger total sectional area of permanent configuration, where permanent magnets 11 are firmly held magnets 11 than do the twelve-pole pole cores. Accordingly, by magnet holder 12 even when strains are applied to even if the decrease in the magnetomotive force of field coil permanent magnets 11 in the direction of the centrifugal 65 8 is taken into account, the output efficiency, i.e., the force, can prevent permanent magnets 11 from protruding generating efficiency of stator coil 5 is improved as com from the area between the claw-like magnetic poles 15 and pared to the conventional technique.

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In addition, as rotor 3 is assembled so that permanent reaching or entering into permanent magnets 11 and thus magnet 11 is held on both ends by magnet holder 12, the die assist in preventing cracks from occurring on permanent control and the manufacturing control of the molding magnets 11. Moreover, even if cracks occur on permanent pressure, etc. can be simplified as compared to a technique magnets 11. it is possible to prevent permanent magnets for molding permanent magnets 11. The assembly of the from flying off as rotor 3 rotates at high speeds as permanent permanent magnets 11 and magnet holder 12 into a single magnets 11 are totally covered by resin. Furthermore, piece can be performed easily, thus reducing the manufac because each of permanent magnets 11 is encompassed with turing cost of rotor 3. resin, the present invention is able to relieve thermal impact FIGS. 6 through 10 illustrate the second embodiment of caused by severe heating and cooling cycles. For example, the present invention. FIG. 6 illustrates the main part of an the temperature can reach between 150° and 180° C. during alternating current generator for a vehicle, and FIGS. 7 generation of electrical power, but returns to ambient air through 9 illustrate a rotor of a rotating electric machine of temperature when the power generation process is stopped. an alternating current generator for a vehicle. Similar parts Because permanent magnets 11 are covered with resin, they to those described above with respect to the first embodi do not experience the extreme thermal impact to which they ment are given the same reference numerals in FIGS. 6 15 might otherwise be subjected. The vibrational impact caused through 10. by small vibrations of a vehicle also does not crack perma nent magnets 11 due to the fact that the magnets are

Rotor 3 of an alternating current generator according to encompassed the second embodiment mainly comprises Lundell-type pole in resin.

cores 7, a field coil 8, two slip rings 9 and 10, sixteen In addition, forces which deform magnet holder 12 radi permanent magnets 11, and magnet holder 12 and rotates ally inward are generated by a difference in the thermal integrally with shaft 6. expansion between magnet holder 12 and claw-like mag Magnet holder 12 of the second embodiment is illustrated netic poles 15 and 16. However, due to the shape in which in FIG. 10. Magnet holder 12 is molded integrally with magnet holder 12 is formed, such a deformative force can be sixteen permanent magnets 11 using resin material such as absorbed with a spring effect. Here, the expansion of the poly-butylene-terephthalate resin (PBT resin) and nylon 66 25 claw-like magnetic poles in the radial direction caused by containing 40% glass fibers. the centrifugal force exerted thereon during rotation can also Magnet holder 12 has sixteen encompassing parts or itself. be absorbed, thus preventing breakage of the magnet holder covering 51 and connecting parts 53 and 54, which inter connect encompassing parts 51. The inner peripheral faces 30 Moreover, as illustrated in FIGS. 8 and 9. encompassing of connecting parts 53 and 54 are formed to have a generally parts 51 intervene between the side faces of permanent arcuate shape. magnets 11 and claw-like magnetic poles 15 and 16. By selecting resin material with adequate permanent set (creep

Each of encompassing parts 51, which is formed as a quantity), square, elongated box-like shape so as to encompass each of even if the magnet holder 12 contacts flange parts permanent magnets 11 therein, contains each of permanent 35 20 through 23 at a single point, the resin material alters its magnets 11 in the state where the opposed faces facing the shape with the creep of the resin materialso that the magnet holder 12 contacts flange parts 20 through 23 in a substan side faces of two adjacent claw-like magnetic poles 15 and tially planar manner, and uniform strain is conveyed to 16, the inner face, and the outer face of each permanent magnet 11 are covered with resin. Each of encompassing permanent ization of magnets 11 without any concentration or local strains, whereby breakage can be prevented.

parts 51 fits between the side faces of two adjacent claw-like magnetic poles 15 and 16. Furthermore, encompassing parts FIG. 11 depicts the third embodiment of the present 51 are formed so as to zig-zag back and forth axially and invention and illustrates apartial sectional view of a rotor for circumferentially between poles 15 and 16 and form a a rotating electric machine, such as an alternating current complete 360° band. Also, each of encompassing parts 51 generator for a vehicle.

suppresses the centrifugal movement of a respective perma 45 Taper parts 61 through 64 are formed on claw-like mag nent magnet 11. netic poles 15 and 16, each of which becomes smaller in On both axial ends of each of encompassing parts 51. . width in the vicinity of the shaft core. By catching the outer connecting parts 53 and 54 are disposed. Connecting parts peripheral face of each encompassing part 51 of magnet 53 and 54 interconnect each two of encompassing parts 51, holder 12 molded integrally with permanent magnets 11, Two adjacent encompassing parts 51 meet in a V-shape at SO taper parts 61 through 64 prevent magnet holder 12 from each of connecting parts 53 and 54. Connecting parts 53 and protruding in the centrifugal direction when rotor 3 rotates S4 are thicker at the positions where encompassing parts 51 at a high speed.

come together. Connecting parts 53 and 54 are independent The second and third embodiments described above refer elements and correspond to claw-like magnetic poles 15 and to the structure where permanent magnets 11 are completely 16. The assembly tolerances between claw-like magnetic 55 covered with resin. On the other hand, as illustrated in FIG. poles 15 and 16 and magnet holder 12 can be absorbed by 12, it is acceptable that exposed parts 55 of permanent modification of each of connecting parts 53 and 54. magnet 11 be provided in resin-made magnet holder 12 and In the circumferential direction of claw-like magnetic that a part of each permanent magnet 11 be exposed through poles 15 and 16, flange parts 20 through 23 are formed to resin-made magnet holder 12 for the purpose of easily prevent magnet holder 12 having permanent magnets 11 burying and molding the permanent magnets 11 in the buried therein from protruding in the centrifugal direction resin-made magnet holder 12. Exposed part 55 allows the when rotor 3 rotates at high speeds. Flange parts 20 through positioning and fixing of permanent magnets 11 to be 23 serve as the catching part and catch the outer faces of performed easily while burying and molding permanent encompassing parts 51 of magnet holder 12. magnets 11.

This embodiment, in which the periphery of each of 55 In addition, the magnetic flux can be further improved by permanent magnets 11 is thoroughly encompassed with resin making resin-made magnet holder 12 from a resin magnetic material, can successfully prevent foreign matter from material and magnetizing resin-made magnet holder 12 in

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the same direction as permanent magnets 11 between the holding parts which contact and support said permanent claw-like magnetic poles. magnets respectively thereon and a connecting part Furthermore, as illustrated in FIG. 13, it is acceptable to which passes circumferentially under said claw-like form resin-made holder 12 with a discontinuity 56 therein. magnetic poles and connects said holding parts circum It is also possible that the discontinuity be formed in ferentially into a ring shape. connecting part 53, thus achieving the same effect. said connecting part having an axial length under said In the fourth embodiment shown in FIG. 14, the magnet claw-like magnetic poles shorter than an axial length of holder 12 primarily comprises a plurality of box-like encom said holding parts and connecting adjacent holding passing or accommodating parts 126 and a connecting part parts at an axial position where the adjacent holding 128 which are made integrally by a resin. Each accommo O parts are most closely adjacent. dating part 126 has a closed wall on the radially outside and 2. A rotor according to claim 1, wherein said magnet an opening through which the permanent magnet 11 is holding member includes:

inserted from the radially inside while flexing concave a plurality of encompassing parts which substantially convex side walls. The connecting part 128 has a width completely encompass and hold each of said plurality (axial length) shorter than the axial length of the accommo 15 of permanent magnets therein. dating part and connects circumferentially in a ring shape 3. A rotor according to claim 1, wherein a part of each of adjacent two of the accommodating parts 126 at only said plurality of permanent magnets is exposed through said generally the axial centers of the accommodating parts 126. magnet holding member.

Thus, the magnet holder 12 is made to flex to a degree 4. A rotor according to claim 1, wherein said magnet necessary for fitting between the pole claws 16 and 17. 20 holding member is made of resin.

In each of the above-mentioned embodiments, the present 5. A rotor according to claim 1, wherein said plurality of invention is applied to rotor 3 of the alternating current claw-like magnetic poles are provided with flange parts generator 1 intended for vehicular use. The present invention extending circumferentially for suppressing a centrifugal is equally applicable to other types of rotary devices. In movement of said magnet holding member. addition, Lundell-type pole cores 7 are used as pole cores in 6. A rotor according to claim 1, wherein: the disclosed embodiments, but St. Paul-type pole cores can 25 said rotating electric machine is an alternating current be also used as pole cores. generator; and

According to the present invention, as permanent magnets said rotor has Lundell-type pole cores. are held so that the permanent magnets do not protrude 7. A rotor according to claim 1, wherein said magnet radially outward from the outer peripheral face of pole cores, 30 holding member is circumferentially discontinuous. the expansion of the air gap between the stator and the rotor 8. A rotor according to claim 1, wherein: can be prevented, thus avoiding degradation of the perfor said connecting part is elastic to allow movement of said mance of rotating electric machines. holding parts to fit in said pole cores. Moreover, as the metallic collision noise caused between 9. A rotor according to claim 1, wherein: the resin-made magnet holding member and permanent 35 said connecting part is disposed to expose radially inner magnets can be suppressed, the generation of high sides of said claw-like magnetic poles at a position frequency impact magnetic noise can be prevented. from which each of said claw-like magnetic poles Furthermore, as the entire resin-made magnet holding extends axially.

member has elasticity, strains applied on the magnet holding 10. A rotor of a rotating electric machine comprising: member can be absorbed and relieved, thus avoiding the a shaft;

deformation and breakage of the magnet holding member pole cores including a plurality of claw-like magnetic and the permanent magnets. Also, the permanent magnets poles formed on an outer periphery thereof, said claw are stably held by the magnet holder. like magnetic poles being constructed and arranged to This invention has been described in connection with engage with each other and rotate integrally with a what are presently considered to be the most practical and rotation of said shaft;

preferred embodiments. However, the present invention is 45 a plurality of permanent magnets each of which is dis not intended to be limited to the disclosed embodiments, but posed between two circumferentially adjacent ones of rather is intended to encompass all modifications and alter said plurality of claw-like magnetic poles and each of native arrangements included within the spirit and scope of which is magnetized in a direction that diminishes the appended claims. magnetic flux leakage between said circumferentially What is claimed is: 5 adjacent ones of said plurality of claw-like magnetic 1. A rotor of a rotating electric machine comprising: poles; and a shaft; a non-magnetic magnet holding member for holding said pole cores including a plurality of claw-like magnetic plurality of claw-like magnetic poles to hold said poles formed on an outer periphery thereof, said claw 55 plurality of permanent magnets said magnet holding like magnetic poles being constructed and arranged to member including holding parts which contact and engage with each other and rotate integrally with a support said permanent magnets respectively thereon rotation of said shaft; and a connecting part which passes circumferentially a plurality of permanent magnets each of which is dis under said claw-like magnetic poles and connects said posed between two circumferentially adjacent ones of holding parts circumferentially into a ring shape, said plurality of claw-like magnetic poles and each of said connecting part being formed with axially concave which is magnetized in a direction that diminishes portions, wherein said magnet holding member magnetic flux leakage between said circumferentially includes:

adjacent ones of said plurality of claw-like magnetic a plurality of base parts extending radially from said poles; and plurality of holding parts for suppressing axial move a non-magnetic magnet holding member for holding said 65 ment of said plurality of permanent magnets; and plurality of permanent magnets, said magnet holding a plurality of catching parts extending axially from said member including a plurality of axially-extending plurality of base parts, said plurality of catching parts

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suppressing a radial movement of said plurality of a catch part extending axially inwardly from a radial outer permanent magnets; end of said base part to restrict a radial movement of wherein said magnet holding member holds said plurality each of said permanent magnets. of permanent magnets such that opposed faces thereof 17. An alternator for a vehicle comprising: facing circumferential side faces of said plurality of 5 a rotor rotatable by an engine and having a plurality of claw-like magnetic poles are exposed and said plurality claw-like magnetic poles with spacing therebetween; of permanent magnets contact said plurality of claw a stator disposed to face said claw-like magnetic poles; like magnetic poles. a plurality of permanent magnets fitted in said spacings, 11. A rotor for a rotating electric machine comprising: respectively; and a shaft; 10 a magnet holder for connecting and holding said perma a field coil; nent magnets, said magnet holder having a plurality of pole cores supporting said field coil thereon and fixed to holding parts holding said permanent magnets in con said shaft, said cores including a plurality of claw-like tact therewith and connecting parts connecting said magnetic poles which are formed on an outer periphery holding parts in generally a ring shape while allowing thereof and extend axially in opposite directions to each 5 movement of said holding parts, so that said permanent other with spacings extending axially therebetween; magnets are fitted in said spacings in correspondence a plurality of permanent magnets disposed in said spac with a form of arrangement of said claw-like magnetic ings; and poles, said connecting parts connecting alternate axial a non-magnetic holding member formed integrally in a ends of adjacent holding parts so that alternating axially generally ring shape and including a plurality of first concave portions are defined about a circumference of parts extending axially and a second part extending said magnet holder, thereby allowing said movement of circumferentially and connecting said first parts said holding parts.

circumferentially, said first parts being disposed in said 18. An alternator according to claim 17, therein: spacings to support said permanent magnets in said said spacings are extended generally axially, inclined with spacings fixedly, and said second part having an axial 25 respect to an axis of said rotor, thereby to form a length shorter than that of said first parts and connect zig-zag shape; and ing adjacent first parts at an axial position where the said connecting parts are set to allow relative turning adjacent first parts are most closely adjacent. movement among said holding parts. 12. A rotor according to claim 11, wherein said first part 19. A rotor for a rotating electric machine comprising: connects two adjacent axial side ends of said second parts 30 a shaft;

and covers each axial end surface of said permanent a field coil;

magnets, and each of said second parts covers four axially pole cores supporting said field coil thereon and fixed to extending side surfaces of each of said permanent magnets. said shaft, said core including a plurality of claw-like 13. A rotor according to claim 11, wherein: magnetic poles which are formed on an outer periphery said second part is elastic to allow movement of said first 35 thereof and extend axially in opposite directions to each parts to fit in said pole cores. other with spacings extending axially therebetween; 14. A rotor according to claim 11, wherein: a plurality of permanent magnets disposed in said spac said second part is disposed to expose radially inner sides ings; and of said claw-like magnetic poles at a position from a non-magnetic holding member formed integrally in a which each of said claw-like magnetic poles extends generally ring shape and including a plurality of first axially.

15. A rotor for a rotating electric machine comprising: parts extending axially and a second part extending a shaft; circumferentially, a field coil; said first parts being disposed in said spacings to support said permanent magnets in said spacings fixedly, and pole cores supporting said field coil thereon and fixed to 45 said second part having an axial length shorter than that said shaft, said cores including a plurality of claw-like of said first parts and connecting said first parts cir magnetic poles which are formed on an outer periphery cumferentially at a first position including an axially thereof and extend axially in opposite directions to each central portion of said first parts while leaving said first other with spacings extending axially therebetween; parts disconnected at a second position axially adjacent a plurality of permanent magnets disposed in said spac to said axially central portion of said first parts. ings; and 20. A rotor according to claim 19, wherein adjacent first a non-magnetic holding member formed integrally in a parts are inclined against said second part to form a V-shape, generally ring shape and including a plurality of first and said second position is provided only at one axial side parts extending axially and a second part extending of said central portion where a circumferential distance circumferentially and connecting said first parts 55 between said adjacent first parts is larger than that at said circumferentially, said first parts being disposed in said axially central portion of said first part. spacings to support said permanent magnets in said 21. A rotor according to claim 19, wherein said first spacings fixedly, wherein said second partis formed in position is provided only at said axially central portion of a ring shape and said first parts are formed to extend said first parts.

from said second part axially in opposite directions 22. A rotor according to claim. 19, wherein said second alternately in a circumferential direction. 60 part is provided only at one position between adjacent first 16. A rotor according to claim 15, wherein each of said parts.

first parts includes: 23. A rotor according to claim 19, wherein adjacent first a board part supporting each of said permanent magnets parts are inclined against said second part to form a V-shape, thereon; said second position is provided at at least one axial side of a base part extending radially from an axial end of said 65 said central portion of said first parts. board part to restrict an axial movement of each of said permanent magnets; and

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UNITED STATES PATENT AND TRADEMARK OFFICE

CERTIFICATE OF CORRRECTION

INVENTOR(S) Shin Kusase, et. al.

It is certified that error appears in the above-identified patent and that said Letters Patent is hereby Corrected as shown below:

Title page, item 56, insert the following:

FOREIGN PATENT OR PUBLISHED FOREIGN PATENT APPLICATION

PUBLICATION COUNTRY OR TRANSLATON

DOCUMENT NUMBER DATE PATENT OFFIC CASS SUBCASS YES NO

Signed and Sealed this

Sixth Day of April, 1999

3.72%- Q. TODD DICKINSON

Attesting Officer Acting Commissioner of Patents and Trude narks