Rotor for a rotating electric machine

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ROTOR FOR A ROTATING ELECTRIC Lundell-type pole cores, which are Subjected to the magne MACHINE tomotive force produced by the field coil. Accordingly, another problem exists, in that high-frequency impact mag

This is a division of application Ser. No. 08/928,525 filed netic noise caused by metallic collision noise is made on Sep. 12, 1997, now U.S. Pat. No. 5,793,144 which was between the claw-like magnetic poles and the non-magnetic a continuation-in-part of application Ser. No. 08/571,217 holding member due to the vibration conveyed from the filed Dec. 12, 1995, now abandoned, which was a division Lundell-type pole cores when the Lundell-type pole cores of application Ser. No. 08/297.838 filed Aug. 30, 1994, now are rotated by rotation of the shaft. U.S. Pat. No. 5,483,116 issued Jan. 9, 1996. Furthermore, in the technique disclosed in Japanese Unexamined Patent Publication 3-265450, as the non

BACKGROUND OF THE INVENTION magnetic ring is formed to have a circular shape with a constant width, Strains are generated which deform the 1. Field of the Invention non-magnetic ring radially inwardly when a difference in The present invention generally relates to a rotor for a thermal expansion exists between the non-magnetic ring and rotating electric machine, Such as alternating current (a.c.) 15 the claw-like magnetic poles. The non-magnetic ring is often generators and electric motors. More particularly, the deformed or broken.

present invention relates to rotary electric machines, which SUMMARY OF THE INVENTION are adapted to hold permanent magnets with a resin-made magnet holding member, where the permanent magnets are It is an object of the present invention to provide a rotor disposed between circumferential Side faces of two adjacent for a rotating electric machine which can prevent perfor claw-like magnetic poles of Lundell-type pole cores, for ing. degradation by preventing an air gap from expand mance 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 25 It is another object of the present invention to provide a inserted between the circumferential side faces of two adjacent claw-like magnetic poles of Lundell-type pole rotor of a rotating electric machine which can Stably hold 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 the field coil (field winding) to improve the output efficiency, member.

In the present invention, pole cores having a plurality of i.e., the electric power generating efficiency of the Stator coil claw-like (armature winding) against the magnetomotive force of the thereof aremagnetic poles formed on the outer periphery 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 40 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 45 member is formed in a ring shape that circuitously com Lundell-type pole cores, and the outer faces of permanent 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. that the resin-made magnet holding member has a plurality Furthermore, another technique is disclosed in Japanese of encompassing parts for encompassing or covering and Unexamined Patent Publication No. 3-265450. This docu 50 holding each of the permanent magnets. Further, connecting ment discloses that a metal or resin-made non-magnetic ring parts interconnect the encompassing parts. The permanent is disposed between claw-like magnetic poles of Lundell magnets may be buried in the resin-made magnet holding type pole cores So that the permanent magnets are held by member.

the non-magnetic ring. In this arrangement, because the plurality of permanent According to the technique disclosed in Japanese UneX 55 magnets are buried in the resin-made magnet holding amined Patent Publication No. 4-165950, which employs a member, it is possible to prevent foreign matter from reach construction where the outer peripheral face of a rotor is ing the magnets, and the formation of cracks on the Surfaces covered with a non-magnetic holding member, a problem of the permanent magnets can be avoided. Moreover, even exists in that the air gap expands between the outer periph if cracks were to occur on the permanent magnets, it is eral faces of the Lundell-type pole cores and the internal 60 possible to prevent the permanent magnets from flying off peripheral face of the Stator core. Thus, the output efficiency, the rotary device Since they are covered with resinous i.e., the electric power generating efficiency of the Stator material. Furthermore, the thermal impact due to the Severe coil, is degraded by the expanding air gap between the outer cooling/heating cycles experienced by a rotating electric peripheral faces of the Lundell-type pole cores and the machine as well as Small vibrations caused by rotation can internal peripheral face of the Stator core. 65 be eliminated.

Furthermore, the metal-made non-magnetic holding The present invention may also be formed so that the member and the permanent magnets are mounted on the resin-made magnet holding member is molded with resin in

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Such a manner that only part of the permanent magnet is According to the present invention, as a plurality of buried therein. When a plurality of permanent magnets are permanent magnets are held by a resin-made magnet holding buried in the molded resin, the permanent magnets can be member fit between the side faces of each of two adjacent held using the exposed parts, thus making the positioning of claw-like magnet poles of Lundell-type pole cores, the gap the magnets quite easy to accomplish. between the outer peripheral face of the rotor and the inner Furthermore, where the resin-made magnet holding mem peripheral expand, face of the Stator, i.e., the air gap, does not 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 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 15 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 to absorb and relieve Strains applied to the magnet holding net holding member holds each of the permanent magnets in member.

a State where the opposed faces facing the Side faces of the BRIEF DESCRIPTION OF THE DRAWINGS claw-like magnetic poles are open and the Side faces of the permanent magnets contact the Side faces of the claw-like inventionobjects,

Other along features and characteristics of the present with methods of operation and the functions magnetic poles. of interrelated parts will become apparent to a perSon Skilled In this arrangement, the assembly of the permanent mag in the art to which the invention pertains from a study of the nets to the resin-made magnet holding member can be easily following detailed description, the appended claims, and the performed. AS the assembly is performed, the magnetic flux 25 attached figures, all of which form a part of this specifica can be easily passed through the claw-like magnetic poles by tion. In the figures:

having the permanent magnets contact the Side faces of the FIG. 1 is a sectional view of the main part of the claw-like magnetic poles. alternating current generator for a vehicle according to a first The present invention may also include a plurality of embodiment of the present invention;

claw-like magnetic poles that are provided with a flange or FIG. 2 is a perspective side view of the rotor of the taper shaped catching parts for Suppressing the centrifugal alternating current generator illustrated in FIG. 1; movement of the resin-made magnet holding member. The FIG. 3 is a sectional view of the main part of the rotor of Size of the catching parts is Set So that the centrifugal force the alternating current generator illustrated in FIG. 1; of the permanent magnets compresses the resin-made mag FIG. 4 is a perspective side view illustrating the state in net holding member on the catching parts. The Suppression 35 which sixteen permanent magnets and a magnet holder are of the permanent magnets and the resin-made holding mem assembled;

ber in the centrifugal direction can be performed with FIG. 5 is a perspective side view of a magnet holder; greater precision, and thus resistance to the centrifugal FIG. 6 is a sectional view of the main part of the forces acting on the permanent magnets and holding mem alternating current generator for a vehicle employed accord ber can be improved. 40 ing to a Second embodiment of the present invention;

The rotating electric machine may be an alternating FIG. 7 is a perspective side view of the rotor of the current generator. The rotor may have Lundell-type pole alternating current generator illustrated in FIG. 6; cores, which allow the resin-made magnet holding member FIG. 8 is a sectional view of the main part of the rotor of holding the permanent magnets to intervene Suitably, and the the alternating current generator illustrated in FIG. 6; power generating efficiency can be improved by the perma 45 FIG. 9 is a perspective side view of the main part of the nent magnets. rotor of the alternating current generator illustrated in FIG. The resin-made magnet holding member does not have to 8;

have both ends thereof interconnected even though it is FIG. 10 is a perspective side view of a magnet holder with formed in a circular manner, thus allowing for Size differ which Sixteen permanent magnets are molded; ences between the permanent magnets and the resin-made 50 FIG. 11 is a sectional view of the main part of the rotor magnet holding member to be easily absorbed. That is, the of the alternating current generator for a vehicle according resin-made holding member may be formed to have a to a third embodiment of the present invention;

discontinuity therein. FIG. 12 is a magnified view of the main part of the magnet It is also possible for the present invention to include pole holder illustrating the modification where part of the per cores having a plurality of claw-like magnetic poles formed 55 manent magnet is exposed;

on the outer periphery thereof, which are assembled So that FIG. 13 is a perspective side view illustrating the modi the claw-like magnetic poles engage with each other and fication where a part of the magnet holder is formed So as to rotate integrally with a rotatable shaft. The present invention be discontinuous, and may also have a plurality of permanent magnets each of FIG. 14 is a perspective view of a magnet holder accord which is disposed between two adjacent claw-like magnetic 60 ing to a fourth embodiment of the present invention. poles of the pole cores and magnetized in the direction that DETAILED DESCRIPTION OF THE diminishes the magnetic flux leakage between the claw-like PRESENTLY PREFERRED EXEMPLARY magnet poles. Further, a resin-made holding member may be EMBODIMENT fit between Side faces of the two adjacent claw-like magnetic poles to hold the permanent magnets. The resin-made mag 65 The rotor of a rotating electric machine according to the net holding member is preferably formed So that it Zig-Zags present invention will now be described with reference to in a complete circle, making repeated V-shaped turns. the attached figures.

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S 6

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 a resin-made holding member and is Singly molded in one plicity of slots (not illustrated) are provided on the internal piece using non-magnetic resin material, Such as poly peripheral face of Stator core 4, and three pairs of Stator coils butylene-terephthalate resin (PBT resin) and nylon 66 which 5 are inserted in the slots. Alternating Voltage is generated on stator coils 5 when rotor 3 rotates. contains 40% glass fibers.

Rotor 3 rotates integrally with shaft 6 and mainly com 15 Magnet holder 12 has sixteen board parts 24 extending prises Lundell-type pole cores 7, field coil 8, slip rings 9 and 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 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 side poles 15 and 16 engage with one another. It is noted that, in faces of two adjacent claw-like magnetic poles 15 and 16, Lundell-type pole cores 7, when an electric current flows are formed to have a Zig-Zag ring shape, which Zig-Zags back through field coil 8, all of claw-like magnetic poles 15 and forth between poles 15 and 16 with repeated V-shaped disposed on one axial side are magnetized to the South (S) turns formed at base parts 26 and 27 (described below). On pole while all of claw-like magnetic poles 16 disposed on the the upper end face (the face on the side opposite shaft 6) of other axial side turn toward the north (N) pole. In the middle each of board parts 24, permanent magnets 11 are individu part of Lundell-type pole cores 7, wound parts 18 and 19 are ally placed So that the inner face of each permanent magnet formed on which field coil 8 is wound a plurality of times 11 contacts the upper end face respectively. around resin-made bobbin 17. 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 40 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. 50 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. 55 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 60 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 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 15 the other Side is diminished, and alternating current Voltage catching parts 32 through 35, as illustrated in FIG. 4, is generated at Stator coils 5 by adding the magnetic flux permanent magnets 11 and magnet holder 12 are assembled. generated by permanent magnets 11 themselves to the 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 to provide entire magnet holder 12 with anti periphery of resin-made bobbin 17. Then, circular plate 13, expansion rigidity while ensuring Some degree of elasticity, disposed on one side, field coil 8, permanent magnets 11 on whereby Strains can be relieved and assembly is performed the magnet holder 12, and circular plate 14 on the other side easily.

of plate 13 are assembled. At this time, as illustrated in 25 AS described above, as alternating current generator 1 is FIGS. 2 and 3, the device is structured so that each of designed 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 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 40 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 50 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 60 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 Rotor 3 of an alternating current generator according to nent magnets 11 due to the fact that the magnets are the Second embodiment mainly comprises Lundell-type pole encompassed 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 be absorbed, thus preventing breakage of the magnet holder covering 51 and connecting parts 53 and 54, which inter itself.

connect encompassing parts 51. The inner peripheral faces 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 Each of encompassing parts 51, which is formed as a Selecting resin material with adequate permanent Set (creep Square, elongated box-like shape So as to encompass each of quantity), 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 material So that the magnet Side faces of two adjacent claw-like magnetic poles 15 and holder 12 contacts flange parts 20 through 23 in a substan 16, the inner face, and the outer face of each permanent tially planar manner, and uniform Strain is conveyed to magnet 11 are covered with resin. Each of encompassing permanent magnets 11 without any concentration or local parts 51 fits between the side faces of two adjacent claw-like 40 ization of Strains, whereby breakage can be prevented. 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 a partial 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 50 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 54 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 60 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 65 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 the first axial end part of the holder has a wall surface claw-like magnetic poles. that is generally perpendicular to an axial direction Furthermore, as illustrated in FIG. 13, it is acceptable to of the magnetic poles and the permanent magnets, form resin-made holder 12 with a discontinuity 56 therein. and

It is also possible that the discontinuity be formed in 5 the wall surface of the first axial end part of the holder connecting part 53, thus achieving the same effect. covers an axial end Surface of two adjacent magnets In the fourth embodiment shown in FIG. 14, the magnet of Said plurality of permanent magnets. holder 12 primarily comprises a plurality of box-like encom 2. The rotor as in claim 1, wherein: passing or accommodating parts 126 and a connecting part the holder further has radially outer parts disposed 128 which are made integrally by a resin. Each accommo between the adjacent two of the first magnetic poles dating part 126 has a closed wall on the radially outside and and Said one of the Second magnetic poles. an opening through which the permanent magnet 11 is 3. A rotor comprising:

inserted from the radially inside while flexing concave convex side walls. The connecting part 128 has a width a Lundell type core having a plurality of claw-like first (axial length) shorter than the axial length of the accommo 15 magnetic poles and a plurality of claw-like Second dating part and connects circumferentially in a ring shape magnetic poles, the first magnetic poles and the Second adjacent two of the accommodating parts 126 at only magnetic poles being arranged alternately in a circum generally the axial centers of the accommodating parts 126. ferential direction to be magnetized in opposite mag Thus, the magnet holder 12 is made to fleX to a degree netic polarities, necessary for fitting between the pole claws 16 and 17. a plurality of permanent magnets disposed between the In each of the above-mentioned embodiments, the present first magnetic poles and the Second magnetic poles, and invention is applied to rotor 3 of the alternating current a holder holding two of the permanent magnets disposed generator 1 intended for Vehicular use. The present invention at both circumferential sides of one of the second is equally applicable to other types of rotary devices. In magnetic poles, the holder having a first axial end part addition, Lundell-type pole cores 7 are used as pole cores in disposed in a Spacing provided between the two, adja the disclosed embodiments, but St. Paul-type pole cores can 25 cent first magnetic poles that are disposed circumfer be also used as pole cores. entially adjacent Said one of the Second magnetic poles, According to the present invention, as permanent magnets wherein the first axial end part of the holder has a wall are held So that the permanent magnets do not protrude Surface that is generally perpendicular to an axial radially outward from the Outer peripheral face of pole cores, direction of the magnetic poles and the permanent the expansion of the air gap between the Stator and the rotor magnets, and can be prevented, thus avoiding degradation of the perfor mance of rotating electric machines. the wall surface of the first axial end part of the holder covers an axial end Surface of Said one of the Second

Moreover, as the metallic collision noise caused between magnetic poles.

the resin-made magnet holding member and permanent 35 4. A rotor comprising:

magnets can be Suppressed, the generation of high frequency impact magnetic noise can be prevented. a Lundell type core having a plurality of claw-like first Furthermore, as the entire resin-made magnet holding magnetic poles and a plurality of claw-like Second member has elasticity, Strains applied on the magnet holding magnetic poles, the first magnetic poles and the Second member can be absorbed and relieved, thus avoiding the 40 magnetic poles being arranged alternately in a circum deformation and breakage of the magnet holding member ferential direction to be magnetized in opposite mag and the permanent magnets. Also, the permanent magnets netic polarities, are stably held by the magnet holder. a plurality of permanent magnets disposed between the This invention has been described in connection with first magnetic poles and the Second magnetic poles, and what are presently considered to be the most practical and 45 a holder holding two of the permanent magnets disposed preferred embodiments. However, the present invention is at both circumferential sides of one of the second not intended to be limited to the disclosed embodiments, but magnetic poles, the holder having a first axial end part rather is intended to encompass all modifications and alter disposed in a Spacing provided between the two, adja native arrangements included within the Spirit and Scope of cent first magnetic poles that are disposed circumfer the appended claims. 50 entially adjacent Said one of the Second magnetic poles,

What is claimed is: wherein the first axial end part of the holder has a wall 1. A rotor for a rotating electric machine comprising: Surface that is generally perpendicular to an axial a Lundell type core having a plurality of claw-like first direction of the magnetic poles and the permanent magnetic poles and a plurality of claw-like Second magnets, and magnetic poles, the first magnetic poles and the Second 55 the wall surface of the first axial end part of the holder magnetic poles being arranged alternately in a circum covers both an axial end Surface of Said one of the ferential direction to be magnetized in opposite mag Second magnetic poles and an axial end Surface of the netic polarities, adjacent two of the permanent magnets. a plurality of permanent magnets disposed between the 5. The rotor as in claim 1, wherein: first magnetic poles and the Second magnetic poles, and 60 the holder has a plurality of first axial end parts including a holder holding two of the permanent magnets disposed Said first axial end part, disposed respectively in all at both circumferential sides of one of the second spacings between adjacent first magnetic poles. magnetic poles, the holder having a first axial end part 6. The rotor as in claim 5, wherein: disposed in a Spacing provided between the two, adja the holder further has a Second axial end part disposed in cent first magnetic poles that are disposed circumfer 65 a spacing provided between two adjacent poles of the entially adjacent Said one of the Second magnetic poles, Second magnetic poles disposed at both circumferential wherein Sides of one of the first magnetic poles.

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7. The rotor as in claim 6, wherein; the wall Surfaces of Said plurality of Second axial end parts the holder has a plurality of Second axial end parts of the holder are in a Second common plane generally including Said Second axial end part, disposed respec perpendicular to the axial direction of the permanent tively in all spacings between adjacent Second magnetic magnets and the magnetic poles. poles. 10. The rotor as in claim 9, wherein: 8. The rotor as in claim 7, wherein: the wall Surfaces of Said plurality of first and Second axial Said plurality of first and Second axial end parts of the end parts of the holder cover corresponding axial end holder all have respective wall Surfaces that are gen Surfaces of all of the permanent magnets. erally perpendicular to an axial direction of the mag netic poles and the permanent magnets. 11. The rotor as in claim 10, wherein: 9. The rotor as in claim 8, wherein: the wall Surfaces of Said plurality of first and Second axial the wall Surfaces of Said plurality of first axial end parts end parts of the holder cover respective axial end of the holder are in a first common plane generally Surfaces of all the magnetic poles. perpendicular to the axial direction of the permanent magnets and the magnetic poles, and k k k k k