AC generator stator for vehicle

Abstract: In an alternator for a vehicle, a stator winding is composed of a plurality of U-shaped conductor segments (33) and an annular member. The conductor segments (33) have connection edges (33f) connected to one another to form ring-connected coil-ends (31), and the annular member (36) covers the ring-connected coil-ends (31) at the connection edges (33f) and portions of the conductor segments (33) adjacent the connection edges (33f). The annular member (36) has a prescribed thickness that provides the ring-connected coil-ends (31) with a prescribed stiffness.

Description: The present invention relates to an AC generator for vehicle such as a passenger car, trucks or the like. It is well known that a stator winding of a vehicle AC generator is composed of a plurality of conductor segments as disclosed in JP-A-63-274335. Because the edge surface of coil-end portions and inclined intersecting portions of the conductor segments are covered with a thick and smooth insulation resin member except for straight portions extending from the stator core, it is difficult to cool the stator winding sufficiently. Because the straight portions are weaker in the circumferential stiffness than the intersecting portions, it is difficult to suppress vibration and the resultant noise. US-A-3151260 discloses an alternator for a vehicle having the features of the preamble of appended claim 1. The known alternator comprises a molded annular coil-end insulator has the shape of a solid resin ring embedding the bent portions of the coil-ends. DE 19529392 A discloses an alternator having limited portions of the coil-ends of its stator coils covered with resin whereby the resin coating is formed by dipping the coil-ends or coil-heads into an impregnation resin which, when cured, holds the coil-ends or coil-heads firmly together. US-A-3400454 describes a dynamoelectric machine having the coil-ends of the stator winding fully encapsulated by a protective sleeve. It is an object of the present invention to provide an improved generator stator that is effective both in cooling the stator winding and in preventing vibration and the resultant noise. This object in accordance with the present invention is achieved by an alternator having the features of appended patent claim 1. Advantageous further developments of such alternator are subject matter of the subclaims. According to a preferred embodiment of the invention, a stator comprises a stator core, a plurality of conductor segments composed of coil-end portions and in-slot portions forming a stator winding, and a ring-shaped resin member connecting the plurality of conductor segments. The plurality of conductor segments form inclined portions intersecting with one another and edge portions at said coil-end portions, and the resin member adheres to the edge portions in a circumferential direction thicker than the inclined portions. Another object of the present invention is to provide an improved stator winding of an AC generator covered by an insulation member which is free from damage due to thermal expansion. The ring-shaped resin member has a wave-shaped configuration corresponding to the outline of the ring-connected coil-ends. Accordingly, this structure protects the stator winding from water and prevents the connection edges from being oxidized and provides the prescribed stiffness as well as sufficient cooling spaces at the coil-ends. In addition, the annular member can have a uniform thickness so that cracks due to uneven thermal expansion can be prevented. 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: Fig. 1 is a cross-sectional side view of a main portion of an AC generator for a vehicle according to a preferred embodiment of the invention; Fig. 2 is a perspective view of a conductor segment forming the stator winding; Fig. 3 is a fragmentary cross-sectional view of the stator; Fig. 4 is a fragmentary side view of the stator; Fig. 5 illustrates connected portions of the conductor segments; Fig. 6 is a fragmentary cross-sectional view of the connected portion; Fig. 7 is a fragmentary perspective view of coil ends at both ends of the stator Fig. 8 is a fragmentary perspective view of a variation of the stator; Fig. 9 is a fragmentary cross-sectional view of a variation of the stator; Fig. 10 is a fragmentary perspective view of the variation of the stator; Fig. 11 is a perspective view of a conductor segment of a variation of the stator; and Fig. 12 is a fragmentary plan view of the variation of the stator. An AC generator for a vehicle according to an embodiment of the present invention is described in detail with reference to the appended drawings. As shown in Fig. 1, an AC generator 1 for a vehicle according to a preferred embodiment of the present invention is composed of stator 2, rotor 3, frame 4, rectifiers 5 and others. Stator 2 is composed of stator core 32, a stator winding having a plurality of conductor segments 33, insulators 34 disposed between conductor segments 33 and stator core 32, and resinous annular member 36 bonding edge portions 33f of coil ends 31 of the stator winding. Annular member 36 is formed from thermosetting epoxy powder as described later. Stator core 32 is composed of laminated thin steel-sheets and has a plurality of slots on the inner periphery thereof. Coil ends 31 is formed of conductor segments 33 extending from stator core 32. Rotor 3 has pole core 7 with six claw poles, cylindrical field coils 8 housed inside claw poles, and shaft 6. Axial-flow type cooling fan 11 is fixed to the front side of the pole core 7 to supply cooling air from the front side of the pole core to the stator winding in axial and radial directions. Centrifugal type cooling fan 12 is also fixed to the rear side of the pole core 7 to supply cooling air from the rear side of pole core 7 to the stator winding in the radial direction. Discharge vents 42 are provided at portions of frame 4 opposite coil ends 31, and intake vents 41 are provided at the front end of the frame 4. As shown in Fig. 2, conductor segment 33 is a U-shaped member made of conductive material (e.g. copper). Conductor segment 33 has turn portions 33c, and an inner layer conductor portion 33a disposed in the radially inner layer of the slot and outer layer conductor portion 33b disposed in the radially outer layer of the slot. Each of inner and outer layer conductors 33a, 33b has in-slot portion to be disposed in the slot and the outside conductor extending outside of the slot to form a portion of coil end 31. As shown in Fig. 3, each of inner layer conductor 33a and outer layer conductor 33b has a rectangular cross-section having longer radial sides than circumferential sides. The conductor segments 33 are coated with insulation film 331 (as shown in Fig. 6). Conductor segments 33 are insulated from the inner walls of slot 35 by insulator 34. As shown in Fig. 4, conductor segments 33 are disposed in stator core 32 so that all turn portions 33c are disposed at one axial end of stator core 32 and all edge portions 33f are disposed at the other end thereof. Inclined portions 33e of coil ends 31 inner layer conductors 33a are inclined to the direction opposite outer layer conductors 33b, so that inner layer conductor 33a and outer layer conductor 33b intersect with each other. Coil-end's edge portions 33f is connected with each other by an ultrasonic or arc welder, a brazing device, or the like. Annular member 36 covers the surface area of edge portions 33f and limited portions of the inclined portion 33e adjacent edge portions 33f to bond or bridge edge portions 33, thereby providing coil ends 31 with enough stiffness against deformation and vibration. Because annular member 36 covers portions adjacent inclined portions 33e, it provides sufficient cooling spaces of a net-work structure in coil ends 31, while it is tightly fixed to conductor segments 33 under vibrations and heat. Annular member 36 also prevents edge portions 33f from being oxidized after they are welded as shown in Fig. 5. Otherwise, when the connected portions are welded together, connected portions A are melted, and the adjacent zones B are damaged or deteriorated with heat, to be subject to be oxidized. As shown in Fig. 6, thin layer 361 is formed on the surface of annular member 36 to cover all the inclined portions 33e and fill small gaps between annular layer 36 and conductor segments 33. In manufacturing, insulators 34 are respectively inserted into the slots of the stator core 32, and conductor segments 33 are inserted into the slots inside insulators 34. As shown in Fig. 7, edge portions 33f are bent in the circumferential directions and connected as described before. Thereafter, thermosetting epoxy powder is applied to the portion indicated by A and B in Fig. 5, by way of fluidized-dipping, that include edge portions 33f and portions of inclined portions 33e, which are heated to form wavy annular member 36 as shown in Fig. 4. The wavy configuration of annular member 36 corresponds to the outline of the leading edge portions 33f. After that, the area of conductor segments 33 covered by the thermosetting resin powder is dipped in liquid resin and heated to form thin layer 361. Since there is a difference in viscosity between the epoxy powder and epoxy liquid, coil ends 31 can be covered with comparatively a thick layer of the epoxy powder and sealed hermetically with epoxy liquid. The connected portions of conductor segments 33 can be ball-shaped as shown in Fig. 8. This structure holds annular member 36 more tightly. This structure can be provided if edge portions 33f are welded by a TIG (tungsten inert-gas) welder. It is important that the connected portions are larger in cross-section than that of conductor segments 33. As shown in Figs. 9 and 10, the stator winding having four conductor segments 133 each slot 135 of the stator core 32 can also provide similar annular member 136. The conductor segments can be shaped into a shape of I or J as illustrated in Fig. 11. Conductor segments 233 is composed of in-slot portion 233h, inclined portions 233i and leading edge portions 233f. In-slot portion 233h is inserted into slot 35, the inclined portions 233i extend from both ends of the stator core 32. At least one inclined portion 233i of two is bent from the shape indicated by broken lines after the conductor segment 233 is inserted into the slot. As shown in Fig. 12, edge portions 233f are connected with one another and covered with the resin member 236. The annular member (36, 136 or 236) can be separated to two or more portions. The resin member can cover wide area of inclined portions 33e if the thickness thereof is reduced, thereby maintaining spaces for cooling-air passages. Bare conductor segments can be also used if each conductor segment is covered with insulator 34. The connected portions are disposed only on the front or rear side of the stator core, so that the resin member 36 can be disposed only on one side of the stator core. In the foregoing description of the present invention, the invention has been disclosed with reference to specific embodiments thereof. Variants, however, are possible within the scope of the invention as defined by the appended claims.

Claims: An alternator for a vehicle including a rotor (3), a stator (2) around the outer periphery of the rotor (3), and a frame (4) supporting said rotor (3) and said stator (2), said stator (2) comprising a stator core (32) with a plurality of slots (35), a plurality of conductor segments (33) composed of coil-end portions (31) and in-slot portions forming a stator winding, and an annular resin member (36) connecting the coil-end portions (31) of said plurality of conductor segments (33) along a circumferential direction of said stator (2), said coil-end portions (31) forming inclined portions (33e) intersecting with one another, and edge portions (33f) being connected to each other, characterized in that said annular resin member (36) covering said edge portions (33f) welded to each other and limited portions of said inclined portions (33e) has circumferential wave-shaped configuration corresponding to the outline of the surface of said edge portions (33f) being welded to each other. The alternator for a vehicle as claimed in claim 1, characterized in that said annular resin member (36) adheres thicker to an area of conductor segments (33) between said edge portions (33f) and said inclined portions (33e) than to said limited portions of said inclined portions (33e). The alternator for a vehicle as claimed in claim 1 or 2, characterized in that a thin-layer (361) different from said annular resin member (36) adheres also to said limited portions of said inclined portions (33e). The alternator for a vehicle as claimed in one of the claims 1 to 3, characterized in that said conductor segments (33) are coated with an insulation film (331), The alternator for a vehicle as claimed in one of the claims 1 to 4, characterized in that portions of said edge portions of said conductor segments (33) welded to each other are ball-shaped and are covered with said annular resin member (36). Method of forming an annular resin member (36) on an alternator for a vehicle including a rotor (3), a stator (2) around the outer periphery of said rotor (3), and a frame (4) supporting said rotor (3) and said stator (2), said stator (2) comprising a stator core (32) with a plurality of slots (35), a plurality of conductor segments (33) composed of coil-end portions (31) and in-slot portions forming a stator-winding and said annular resin member (36) connecting the coil-end portions (31) of said plurality of conductor segments (33) along a circumferential direction of said stator (2), said coil-end portions (31) forming inclined portions (33e) intersecting with one another, and edge portions being connected to each other, the method comprising the steps of applying thermosetting epoxy powder to the edge portions (33f) and to a limited portion of each said inclined portions (33e) by way of fluidized dipping and heating said edge portions and limited portions of each said inclined portions (33e) to form a wave-shaped annular resin member (36) corresponding to the outline of the surface of said edge portions (33f) being welded to each other. The method of claim 6, characterized in that the area of the conductor segments (33) covered with the thermosetting resin-power is dipped in liquid resin and heated to form a thin resin layer (361) so that the coil-end portions (31) are partly covered with a comparatively thick layer of epoxy powder and sealed hermetically with liquid resin.

Inventors: KUSASE SHIN, SHIGA TSUTOMU, UMEDA ATSUSHI, KUSASE, SHIN, SHIGA, TSUTOMU, UMEDA, ATSUSHI
Applicants: DENSO CORP, DENSO CORPORATION
Application year: 1999
Main classification: H02K3
IPC codes: H02K3