Vehicle AC generator stator

[0002] The present application is based on and claims priority from Japanese Patent Application Hei 10-335639 filed on Nov. 26, 1998, the contents of which are incorporated herein by reference.

[0003] 1. Field of the Invention

[0004] The present invention relates to a vehicle AC generator stator, and particularly a stator winding arrangement.

[0005] 2. Description of the Related Art

[0006] PCT application WO92/06527 discloses a stator winding arrangement, which is composed of U-shaped conductor segments welded to one another at their connection ends. The connection ends are disposed in a circular layer at one end of the stator core at equal intervals. Each U-shaped conductor segment has two in-slot portions inserted into a pair of slots, and four in-slot portions are disposed in each slot. Accordingly, four connection ends extend from each slot to be welded to form a stator winding. Because all the connection ends are aligned in the circular layer, the interval between welded junctions of the connection ends becomes so small that insulation between the junctions becomes difficult, and that cooling air can not pass therethrough very well.

[0007] A main object of the invention is to provide an improved stator having a stator winding composed of a plurality of conductor segments.

[0008] Another object of the invention is to provide an improved stator winding composed of a plurality of conductor segments welded to one another at connection ends that are sufficiently spaced apart from one another.

[0009] According to a preferred embodiment of the invention, each of a plurality of conductor segments of a stator winding includes an in-slot portion and an inclined coil-end portion having a connection-end positioned in a circular layer corresponding to a slot-layer. The connection-end in one of a plurality of circular layers is connected to another connection-end in an adjacent circular layer to form a junction radially and circumferentially spaced apart from other junctions. Each of the segments can have another connection-end positioned in a circular layer at the opposite core end corresponding to the slot layer.

[0010] More specifically, a stator winding comprises a plurality of sets of U-shaped large and small segments including a pair of in-slot portions each disposed in one of a plurality of radially aligned slot-layers and contiguous inclined coil-end portions each having a connection-end. The pair of in-slot portions of the large segment is disposed in a pair of the slots one-pole pitch spaced apart from each other so that one in-slot portion is disposed in the innermost slot-layer of one of the pair of slots and the other in-slot portion is disposed in the outermost slot-layer. One of the connection-ends of the large segment is positioned in the innermost circular layer corresponding to the innermost slot-layer formed at an end of the stator core, and the other of the connection-ends is positioned circumferentially spaced apart from the one of the connection ends in the outermost circular layer corresponding to the outermost slot-layer. The pair of in-slot portions of the small segment is disposed in the pair of the slots so that one in-slot portion is disposed in the inner middle slot-layer of one of the pair of slots and the other in-slot portion is disposed in the outer middle slot-layer. One of the connection-ends of the small segment is positioned in the inner middle circular layer corresponding to the inner middle slot-layer to be in contact with the coil-end of the large segment positioned in the innermost circular layer to form an inner junction, and the other of the connection-ends is positioned circumferentially spaced apart from the one of the connection ends in the outer middle circular layer corresponding to the outer middle slot-layer to be in contact with the coil-end of the large segment positioned in the outermost circular layer to form an outer junction.

[0011] Other objects, features and characteristics of the present invention as well as the functions of related parts of the present invention will become clear from a study of the following detailed description, the appended claims and the drawings. In the drawings:

[0012] FIG. 1 is a cross-sectional view of an AC generator for a vehicle equipped with a stator according to a preferred embodiment of the invention;

[0013] FIG. 2 is a perspective view of conductor segments of the stator according to the preferred embodiment;

[0014] FIG. 3 is a fragmentary cross-sectional view of the stator according to the preferred embodiment;

[0015] FIG. 4 is a schematic side view illustrating coil-end portions of the stator according to the preferred embodiment;

[0016] FIG. 5 is a schematic plan view illustrating the coil end portions illustrated in FIG. 4;

[0017] FIG. 6 is a schematic view illustrating a welding process of the stator according to the preferred embodiment;

[0018] FIG. 7 is a fragmentary schematic view illustrating a variation of the stator according to the preferred embodiment;

[0019] FIG. 8 is a fragmentary schematic view illustrating another variation of the stator according to the preferred embodiment; and

[0020] FIG. 9 is a perspective view illustrating a variation of a conductor segments of the stator according to the preferred embodiment.

[0021] The invention is described with reference to the appended drawings.

[0022] As shown in FIG. 1, a vehicle AC generator 1 includes stator 2, rotor 3, frame 4 and rectifier 5.

[0023] Stator 2 includes stator core 22, a stator winding composed of a plurality of conductor segments 23, and a plurality of insulators 24 disposed between stator core and each of conductor segments 23.

[0024] Rotor 3 includes, shaft 6, a pair of front and rear pole cores 7 and a cylindrically wound field coil 8. One pole core 7 has six claw poles extending to interleave with six claw poles of the other pole core 7, thereby enclosing field coil 8. Front pole core 7 has mixed flow cooling fan 11 welded to the front surface thereof, and rear pole core 7 has centrifugal cooling fan 12 welded to the rear surface thereof.

[0025] Frame 4 accommodates stator 2 and rotor 3 so that rotor 3 can rotate with shaft 6 within the inner periphery of stator core 22. Frame 4 has a plurality of air-discharge windows 42 at portions thereof surrounding the coil-ends of the stator winding, and a plurality of air-intake windows 41 at the radially inner portions of the opposite ends thereof.

[0026] AC generator 1 is driven by an engine through a belt (not shown) and pulley 20 which is carried by the front end of shaft 6.

[0027] When field coil 8 is energized by an outside battery (not shown), the claw poles are polarized to supply magnetic flux to the stator winding, thereby generating AC output power. Rectifier 5 converts the AC output power to DC power.

[0028] As shown in FIG. 2, conductor segments 23 are formed to a plurality of sets of U-shaped large and small segments 231 and 232. Large segment 231 has a pair of in-slot portions 231aand 231b,a pair of connection-ends 231dand 231erespectively extending from the pair of in-slot portions 231aand 231bthrough outwardly inclined coil-end portions 231g,and turn portion 231c.Small segment 232 has a pair of in-slot portions 232aand 232b,a pair of connection-ends 232dand 232erespectively extending from the pair of in-slot portions 232a,232bthrough inwardly inclined coil-end portions 232g,and turn portion 232c.Turn portion 231cof large segment 231 surrounds turn portion 232cof small segment 232 at the lower axial end of stator core 22, and coil-end portions 231gof large segment 231 are longer than coil-end portions 232gof small segments 232. It is also possible that coil-end portions 231gare made shorter than coil-end porions 232g.

[0029] One in-slot portion 231aof large segment 231 is disposed in the radially innermost layer of one slot 25, and the other in-slot portion 231bof the same segment 231 is disposed in the radially outermost layer of another slot 25 which is one pole-pitch spaced apart therefrom in the clockwise direction. One in-slot portion 232aof small segment 232 is disposed in the radially inner middle layer of the same slot as in-slot portion 231a,and the other in-slot portion 232bof the same segment 232 is disposed in the radially outer middle layer of the same slot as in-slot portion 231b.

[0030] As shown in FIG. 3, in-slot portions 231aand 231b′of two large U-shaped conductor segments 231 and 231′ and in-slot portions 232aand 232b′ of two small conductor segments 232 and 232′ are inserted into one slot 25 in radially aligned four layers.

[0031] As shown in FIGS. 4 and 5, connection-end 231d′ is positioned in the radially innermost circular layer formed at the upper axial end of stator core 22. Connection-end 231d′ is also positioned at an apex of a scalene triangle formed of counterclockwise or left inclined longer coil-end portion 231g′ extending from in-slot portion 231aas one side, which is inserted in the radially innermost slot-layer of one slot 25, and clockwise or right inclined shorter coil-end portion 232gextending from in-slot portion 232aas the other side, which is inserted in the inner middle slot-layer of another slot 25 that is one-pole pitch spaced apart from the one slot. Connection-end 232dis positioned in the inner middle circular layer at the same apex as connection-end 231d′ to be in contact therewith to form an inner junction 233a.

[0032] Connection-end 232eis positioned in the outer middle circular layer formed at the same axial end at an apex of a scalene triangle having counterclockwise inclined shorter coil-end portion 232gextending from in-slot portion 232binserted in the outer middle slot-layer of the one slot as one side and clockwise inclined longer coil-end portion 231g′ extending from in-slot portion 231b′ inserted in the outermost slot-layer of the another slot 25 as the other side. Connection-end 231e′ is positioned in the outermost circular layer at the same apex as connection-end 232eto be in contact therewith to form an outer junction 233b. Thus the above two apexes are spaced apart from each other both in the radial direction and circumferential directions.

[0033] Connection-ends 231d′ and 232don the same apex are welded together to form a first junction 233a,and connection ends 232eand 231e′ on the same apex are welded together to form a second junction 233bthat is spaced apart from the first junction 233a,so that two large segment 231 and 231′ are series connected by small segment 232.

[0034] All the sets of U-shaped large and small segments 231 and 232 are inserted, arranged and welded in the same manner as described above to form the stator winding. Thus, a plurality of junctions 233aand also a plurality of junctions 233bare respectively disposed in two concentric circular layers. The plurality of first junctions 233aand the plurality of second junctions 233bare shifted circumferentially from one another so that each of first junctions 233acan be disposed between two of second junctions 233b.

[0035] Because all the junctions, 233a,233bare disposed in two circular layers and circumferentially spaced apart from one another, not only cooling air can pass between the coil-end portion easily but welding process can be carried out efficiently as shown in FIG. 6, where two or more welders C1 and C2, such as tungsten inert gas welders, can be used.

[0036] The U-shaped segments shown in FIG. 2 can be substituted by segments having one in-slot portion and a pair of connection-ends formed at the opposite ends thereof as shown in FIG. 7. The lower connection-end can be formed after it is inserted into the slot as shown by dotted lines. The coil-end portion disposed in the outermost and the innermost circular layers are longer or shorter than the coil-end portions disposed in the outer middle and inner middle circular layers to have the circumferential spaces between the junctions of the connection portions.

[0037] Each set of conductor segments 23 can be composed of three kinds of U-shaped segments, large, medium, and small segments. The stator winding can be formed substantially in the same manner as the above. In such a case, junctions 233a,233b, 233care respectively distributed in three circular layers or lines r1, r2, r3 at an axial end of the stator core as shown in FIGS. 8 and 9.

[0038] In the foregoing description of the present invention, the invention has been disclosed with reference to specific embodiments thereof. It will, however, be evident that various modifications and changes may be made to the specific embodiments of the present invention without departing from the broader spirit and scope of the invention as set forth in the appended claims. Accordingly, the description of the present invention in this document is to be regarded in an illustrative, rather than restrictive, sense.