AU729271B2 - Alternator for an automotive vehicle - Google Patents

Description

AUSTRALIA

Patents Act 1990 COMPLETE. SPECIFICATION STANDARD PATENT Applicant(s): DENSO CORPORATION Invention Title: Alternator for an Automotive Vehicle The following statement is a full description of this invention, including the best method of performing it known to me/us: 3.

ALTERNATOR FOR AN AUTOMOTIVE VEHICLE BACKGROUND OF THE INVENTION The present invention relates to an alternator for an automotive vehicle, which is preferably installed in a passenger vehicle, a truck or the like.

To reduce the aerodynamic resistance in a traveling condition, a vehicle body tends to be formed into a slant nose shape. Securing a sufficient residential space for a passenger compartment is earnestly demanded. To satisfy these requirements, engine rooms of automotive vehicles have been becoming so narrow and crowded that only limited space is available for installing an alternator. Meanwhile, to improve fuel economy, the rotation of an engine tends to be reduced. Correspondingly, the rotation of an alternator is lowered. On the other hand, there is a need for increasing electric loads such as safety control devices etc. Thus, improving the generating ability of the alternator is strongly required. In other words, a compact, powerful, and non-expensive automotive alternator is required.

Furthermore, there is a social requirement that noises leaking from vehicles need to be reduced. Providing a quiet passenger compartment leads to increase of product appeal. To this end, the engine noises have been recently lowered. However, accessories of the engine need to rotate at relatively higher speeds. Especially, fan noises and magnetic noises of automotive alternators are becoming main noises emitted from the automotive vehicles.

Conventionally, a stator winding generally used in an automotive 25 alternator is arranged by using a continuous wire assembled with a stator core. In such a stator winding arrangement, various improvements have been S::.:proposed for satisfying the requirements of compactness, higher output, lower *:*noises etc.

For example, as disclosed in Published Unexamined Japanese Patent 30 Application No. 7-393351, providing a shorter winding is effective to reduce "the winding resistance. According to a 2/3-t short-pitch winding technique, S. the winding is wound without causing interference between phases in a radial Page Page 1 direction. However, there is a problem that the winding factor is worsened largely and accordingly a generated voltage is reduced greatly. Furthermore, there is a problem that a winding operation is difficult.

Furthermore, according to other proposed techniques, coil ends are pre-shaped or thinned to avoid the interference during a winding operation.

However, there is a problem that the winding operation is complicated and the winding resistance value is increased. Furthermore, according to these techniques, the interference of the coil ends cannot be solved completely. In each slot, the coil is located in an offset condition where no more than half of a cross section is available as a geometrical space for accommodating the coil. This brings a drawback that the resistance cannot be reduced. Due to the above-described offset arrangement of the coil in the slot, the coil configuration becomes different in each phase. This makes the resistance value and the inductance of the winding different in each phase. Thus, the flow of current is differentiated in each phase, causing a local temperature increase which possibly brings a problem that the performance of the alternator is worsened and the magnetic noise may increase.

For example, as disclosed in Published Unexamined Japanese Patent Application No. 59-159638, the coil end may be formed into a flattened configuration to improve the air flow resistance. However, according to the arrangement shown in this prior art, the air flow resistance is still high. A sufficient cooling ability cannot be expected. The noises cannot be reduced satisfactorily.

~Furthermore, to a realization of compactness and high output, there is 25 a technique for increasing the magnetic flux by reducing an air gap between a rotor and a stator. However, there is a necessity of enlarging a crosssectional area of a stator core in accordance with an increase of the magnetic flux. This forcibly reduces a slot area, with an increase of the winding resistance. As a result, an effect of increased output is substantially canceled.

30 In short, it is important to optimize the balance between the core and the winding which cooperatively constitute the stator.

To obtain an improved output, an optimization will be attained in the Page 2 selection of design data for the core cross section and the winding. However, a remaining problem to be solved is a cooling of coil ends which serve as a heat generation source. For example, a large-scale fan will be required for cooling the electric conductors through an insulating film and a fixing member provided on the surface thereof The fan needs to be disposed adjacent to the coil ends. However, according to a conventional winding, coil ends are undulated due to the interference between different phases. This increases the fan noises of higher orders. When these noises are nuisance for vehicle passengers, these noise must be reduced. For example, the inner face of the coil ends facing to the fan is smoothed as an ideal surface by using a complicated winding method. Or, the cooling air amount is reduced by victimizing the fan efficiency.

Furthermore, in the process of seeking the compactness and the higher output, there will be a problem that the magnetic noise is increased due to an increased magnetic force acting between the rotor and the stator. In general, an automotive alternator is equipped with a rectifier which cuts the output voltage at a predetermined level to charge a battery. Thus, the generated voltage has a rectangular waveform. Accordingly, it is known that spatial higher harmonics in a clearance between the stator and the rotor chiefly comprise tertiary higher harmonic components. Accordingly, a magnetic force acting between the stator and the rotor comprises the square components of the tertiary higher harmonic components. The magnetic force thus cased will generate a magnetic ripple force.

To eliminate such magnetic forces, Published Unexamined Japanese 25 Patent Application No. 4-26345 proposes to use two sets of three-phase windings which are mutually phase shifted by an electric angle of 300. Two outputs of these two three-phase windings are combined so that their magnetic ripple forces can be canceled each other. However, this conventional winding arrangement cannot solve the coil end interference 30 derived from the conventional winding configuration. The number of required slots is doubled. This forcibly requires a careful winding operation for a thin wire wound in the slots. This problem is difficult to solve. Namely, when the Page 3 compactness and higher output are aimed, there are many problems to be newly solved.

In this manner, the stator winding using a continuous wire is widely used in conventional automotive alternators. However, this type of stator winding cannot satisfy all of the requirements, such as compactness, higher output and lower noises, which are contradictory to each other.

On the other hand, a general large generator, such as an induction type generator, may comprise two layered conductors accommodated in a stator slot which constitute inner and outer layers disposed in a radial direction of the stator slot. To eliminate the interference between different phases at the coil ends, the conductors of the inner and outer layers are alternately connected.

However, there was a problem that the above-described larger generator could not be directly used as an automotive alternator. More specifically, the automotive alternator needs to supply electric power to the automotive electric loads in an engine idling condition corresponding to the lowest engine speed region equivalent to the alternator's rotation range of approximately 1,500 rpm. To this end, it is mandatorily necessary to generate approximately 15 V, which is equivalent to a sum of a battery voltage and a diode drop, at the above-described rotational speed range, approximately 1,500 rpm or less. However, for an automotive alternator of 1 to 2 kW used for a general passenger vehicle or a truck, it is difficult to generate 15 V at .such a low rotation. The above-described general large induction type generator has about two conductors per slot which is chiefly dependent on a 25 magnetic flux determined by the physical size. When the number of the conductors is as small as two, it is difficult to supply a sufficient electric power because an electromotive voltage cannot be obtained satisfactorily at the above-described low rotation region. Furthermore, there is a recent tendency that the idling rotation is further reduced to improve the fuel 30 economy. However, responding to such a requirement is difficult for the above-described general large induction type generator.

Furthermore, to increase an output at a low-speed region, it may be Page 4

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possible to employ a multi-polarized arrangement operated by higher frequencies. For this end, the above-described general large scale generator uses a salient rotor having an axial length substantially equal to that of the stator core. According to the salient rotor, a magnetomotive force of each magnetic pole is reduced in response to an increase of the magnetic pole number because of a reduction of a wiring space in the rotor. Thus, it is difficult to increase the output. In other words, the above-described automotive alternator cannot satisfy the required performances.

In general, providing a clearance inside the salient rotor is structurally difficult. Thus, there is a problem that the cooling air cannot be introduced and guided to an inner peripheral surface of the rotor. Furthermore, the cooling air cannot be introduced and guided to a field coil provided in the rotor.

Furthermore, Published Unexamined Japanese Patent Applications No.

62-272836, No.63-274335 and No. 64-5340, disclose automotive alternators which use U-shaped electric conductors, so-called conductor bars.

However, according to these prior art, a plurality of stator cores are laminated in a circumferential direction so as to form a cylindrical shape. Thus, a magnetic resistance increases with respect to a passing direction of the magnetic flux. A required performance cannot be realized. There are many problems to be solved, for example, maintenance of the practical strength.

Furthermore, WO92/06527 proposes an arrangement of an automotive alternator which uses conductor bars for a stator. According to the arrangement shown in this prior art, a total of four electric conductors are disposed in a square shape in each slot. In a slot, a clearance is provided between two electric conductors arrayed in a circumferential direction at a coil end. According to a conventional ventilation structure for an automotive alternator, a cooling fan is conventionally provided outside a frame. A ventilation passage is provided for guiding cooling air in the axial direction.

30 On the contrary, according to the present ventilation structure, a cooling fan "is located inside a frame so that cooling air can be directly supplied to the coil end. With this arrangement, the cooling ability is greatly improved so that Page compactness and higher output can be realized. Accordingly, providing a clearance between coil ends makes it possible to reduce the air resistance and increase the cooling ability.

Furthermore, using the U-shaped conductor bars makes it easy to insert the conductor bars into slots offset by a magnetic poler pitch.

However, according to this arrangement, the cross section of each electric conductor is limited. If the cross section of each electric conductor is forcibly increased to reduce the electric resistance and increase the output, it will not be possible to provide the above-described clearance. This will significantly worsen the cooling ability and formability at the coil end. To secure a sufficient clearance, it may be effective to reduce the number of electric conductors from four to two per slot.

However, such a smaller number of conductors will not be able to generate an output at an idling rotation, at a low-speed region. Thus, it cannot be used as an automotive alternator.

Furthermore, USP 2,928,963 proposes an AC generator which comprises a stator using conductor bars and a Lundel-type pole core. However, according to this invention, a ventilation structure extends only in an axial direction. This ventilation structure differs from the present general ventilation structure. Furthermore, even in an arrangement shown as another embodiment, no internal fan ~is provided. In view of the foregoing, it is concluded that no improvement is shown for increasing the cooling ability to realize both of compactness and higher output.

30 Furthermore, according to the arrangement disclosed in this prior art, each slot accommodates two conductors. Thus, as described above, it will be difficult to obtain an output at the lower-speed region.

SUMMARY OF THE INVENTION 35 In view of the above-described problems encountered in the prior art, the present invention preferably provides a highly practical and improved alternator for an automotive vehicle which is capable of satisfying performances required for recent alternators.

The present invention further preferably provides an alternator for an automotive vehicle which is compact in Page 6 S:14339bl.doc -7 Size, powerful in output, and calm in noise level.

The present invention preferably further provides an arrangement for a rotor and a stator winding which is capable of producing an output required at a low-speed region of an alternator, and to provide a novel cooling arrangement for the coil end of a stator winding, thereby providing an alternator capable of obtaining a high output required for automotive alternators, suppressing a reduction in efficiency due to heat generation, and preventing a reduction in an output.

The present invention preferably further provides an alternator for an automotive vehicle which is capable of improving a space factor in a slot of a stator winding as well as increasing a cooling ability and reducing noises at the outside of the slot as a result of a cooperation with the rotor.

The present invention preferably further provides an alternator for an automotive vehicle, comprising: 2a field rotor with N and S poles formed alternately S 20 in a circumferential direction, a stator including a stator o core disposed in a confronting relationship with said -rotor and a multi-phase stator winding associated with said stator core, and a frame supporting said rotor and said stator, wherein *o 25 said field rotor comprises a Lundel-type core having .o a plurality of hooked magnetic poles serving as said N and S poles, said stator core comprises laminated cores formed 30.with a plurality of slots extending across laminated 30 plates, said multi-phase stator winding comprises a plurality of conductor segments, said plurality of conductor segments constitute at least a first pair of conductors including an inner-layer conductor and an outer-layer conductor and a second pair of conductors including an inner layer conductor and 8 an outer layer conductor, said first and second pairs of conductors are arrayed in a line in only a depth direction of each slot, and said conductor segments are insulated from each other in each slot, said plurality of conductor segments are partly disposed out of said slots so as to extend from an end face of said stator core and form a coil end having a predetermined connecting pattern according to which an inner-layer conductor and an outer-layer conductor of each pair of conductors disposed in different slots spaced at predetermined intervals corresponding to a magnetic pole pitch of said field rotor are serially connected, thereby forming a coil end group chiefly repeating said connecting pattern at the end face of said stator core, and said plurality of conductor segments of said coil end extend in a direction intersectional with a flow direction of cooling air introduced in said frame, so that the cooling air can flow across said conductor segments of said ,coil end.

S 20 Preferably, the Lundel-type core is defined by the following relationship Ll/L2 where L1 represents an outer diameter of the hooked magnetic pole of said Lundel-type rotor, and L2 represents a length in a rotational axis of said Lundel-type rotor.

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25 In accordance with a second aspect of the present invention there is provided an alternator for an automotive vehicle, comprising: a field rotor with N and S poles formed alternately 3 in a circumferential direction, a stator including a stator 30 core disposed in a confronting relationship with said rotor and a multi-phase stator winding associated with said stator core, and a frame supporting said rotor and said stator, wherein 9said stator core has a plurality of slots for accommodating said multi-phase winding, said multi-phase stator winding comprises a plurality of conductor segments, said plurality of conductor segments constitute at least two pairs of conductor segments arrayed in a line in only a depth direction of each slot, and said conductor segments are insulated from each other in each slot, said plurality of conductor segments are arranged such that said conductor segments of each pair of conductor segments disposed in different slots spaced at predetermined intervals corresponding to a magnetic pole pitch of said field rotor are similarly connected, said plurality of conductor segments are partly disposed out of said slots so as to extend from an end face of said stator core and form a coil end, said plurality of conductor segments are partly disposed out of said slots so as to extend from an end face of said stator core and form a coil end, 20 said plurality of conductor segments are mutually connected so as to form a plurality of joint portions, and said plurality of joint portions are arranged into '"*multiple loops and mutually spaced in both a circumferential direction and a radial direction.

In accordance with a third aspect of the present invention there is provided an alternator for an automotive vehicle, comprising a field rotor with N and S poles formed alternately in a circumferential direction, a stator including a stator core disposed in a confronting 30 relationship with said rotor and a multi-phase stator winding associated with said stator core, and a frame supporting said rotor and said stator, wherein said field rotor comprises a Lundel-type core having a plurality of hooked magnetic poles serving as said N and S poles, said stator core comprises laminated cores formed with a plurality of slots extending across laminated plates, 9a said multi-phase stator winding comprises a plurality of conductor segments, said plurality of conductor segments constitute at least a first pair of conductors including an inner-layer conductor and an outer-layer conductor and a second pair of conductors including an inner layer conductor and an outer layer conductor, said first and second pair of conductors are arrayed in a line in only a depth direction of each slot, and said conductor segments are insulated from each other in each slot, said plurality of conductor segments are partly disposed out of said slots so as to extend from an end face of said stator core and from a coil end having a predetermined connecting pattern according to which an inner layer conductor and an outer layer conductor of each pair of conductors disposed in different slots spaced at predetermined intervals corresponding to a magnetic pole pitch of said field rotor are serially connected, thereby forming a coil end group chiefly repeating said connecting 20 pattern at the end face of said stator core, and two coil ends belonging to two adjacent slots are spaced from each other due to a distance between said two adjacent slots in the circumferential direction.

BRIEF DESCRIPTION OF THE DRAWINGS 25 Fig. 1 is a vertical cross-sectional view showing a first embodiment of the present invention; *o *oo oooo* •ego Fig. 2 is a view showing an appearance of a stator in accordance with the first embodiment of the present invention; Fig. 3 is a perspective view showing a conductor segment 33 in accordance with the first embodiment of the present invention; Fig. 4 is a cross-sectional view showing part of the stator in accordance with the first embodiment of the present invention; Fig. 5 is a perspective view showing coil ends located at both ends of the stator in accordance with the first embodiment of the present invention; Fig. 6 is a development showing a winding connection of the stator including #1 to #48 slots; Fig. 7 is a development showing a winding connection of the stator including #49 to #96 slots, where a series of stator winding is formed when Figs. 6 and 7 are roundly connected at lines V-V and VI-VI; Fig. 8 is a circuit diagram showing an alternator for an automotive vehicle; C* o• eo* 10 Fig. 9 is a graph showing an output performance of the alternator for an automotive vehicle; Fig. 10 is a view showing a partial appearance of a stator in accordance with a second embodiment; Fig. 11 is a perspective view showing a conductor segment 33 in accordance with the second embodiment of the present invention; Fig. 12 is a cross-sectional view showing part of the stator in accordance with the second embodiment of the present invention; Fig. 13 is a perspective view showing the coil end of a stator in accordance with a third embodiment of the present invention; Fig. 14 is a cross-sectional view showing part of the stator in accordance with the third embodiment of the present invention; Figs. 15 and 16 are developments cooperatively showing a winding connection of the stator in accordance with a fourth embodiment of the present invention, where a series of stator winding is formed when Figs. and 16 are roundly connected at lines VII-VII and VIII-VIII; Fig. 17 is a circuit diagram showing an alternator for an automotive vehicle in accordance with the fourth embodiment of the present invention; Figs. 18 and 19 are vertical cross-sectional views showing other embodiments of the present invention; Figs. 20 and 21 are developments cooperatively showing a winding connection of the stator in accordance with other embodiment of the present invention, where a series of stator winding is formed when Figs. 20 and 21 Sare roundly connected at lines IX-IX and X-X; Fig. 22 is a perspective view showing a winding end of the stator in accordance with the first embodiment; and Fig. 23 is a perspective view showing a winding end of the stator in accordance with another embodiment.

30 DESCRIPTION OF THE PREFERRED EMBODIMENTS An alternator for automotive vehicles will be explained hereinafter in accordance with each embodiment of the present invention with reference to Page 11 the accompanied drawings.

Arrangement of First Embodiment Figs. 1 through 8 cooperatively show a first embodiment of the present invention. Fig. 1 is a view showing an essential structure of an automotive alternator which is preferably employed an automotive vehicle. Figs. 2 through 8 are views illustrating a stator in accordance with the first embodiment.

The automotive alternator 1 comprises a stator 2 serving as an armature, a rotor 3 serving as a field, a frame 4 supporting both of the rotor 3 and the stator 2, and a rectifier 5 directly connected to the stator 2 for converting alternating-current power into direct-current power. An output of the rectifier 5 is connected to a battery of 12 V.

The rotor 3 integrally rotates together with a shaft 6. The rotor 3 comprises a pair of Lundel-type pole core 7, a cooling fan 11, a field coil 8, slip rings 9 and 10, a total of 16 -permanent magnets 51. The permanent magnets 51 are connected each other by a magnet holder (not shown).

Each permanent magnet 51 interposed between field cores is a ferrite magnet of a rectangular parallelopiped. The dimensions are 8 mm in the width between magnetic poles, 24 mm in the axial length, and 9 mm in the radial length. The field coil used for this alternator is a rectangular conductor having a resistance value of 1.8 Q and a turn number of 330 T. Furthermore, the permanent magnet 51 used for this alternator is a wet anisotropic magnet.

This magnetic member can suppress the reduction in the magnetic property within 5% when it is fully magnetized at the temperature of -30 0 C or below.

The pole core 7 has a boss having a diameter of 4) 50 mm and a shaft 6 having a diameter of 17 mm. A referential cross section is obtained by subtracting a cross section of the shaft 6 from a cross section of the boss portion of the pole core. This referential cross section is divided by the poler pair number. The resultant value is referred to as a reference value. In 30 determining respective magnetic poler cross sections, the referential value is set to the same value.

The shaft 6 is connected to a pulley and driven by an engine (not Page 12 shown) installed on an automotive vehicle for traveling.

The pole core 7 comprises a boss portion 71 assembled with the shaft 6, two disk portions 72 extending radially from both ends of the boss portion, and a total of 16 magnetic poles 73 disposed at a distal end of the disk portion 72.

The frame 4 has axial end portions where two inlet holes 41 and 42 are opened for introducing cooling air. Furthermore, the frame 4 has an outer peripheral portion where outlet holes 43 and 44 are opened for scavenging the exhausted cooling air. The output holes 43 and 44 are arranged in two annular rows at portions facing to the coil end 31. An outer diameter of the pulley is set to be larger than an outer diameter of the inlet hole 41 provided at the axial end surface of the frame 4.

The stator 2 comprises a stator core 32, conductor segments 33 constituting the stator winding, and insulators 34 electrically insulating the conductor segments 33. The stator 2 is supportedby the frame 4. The stator core 32 is fan assembly of laminated thiin steel plates. A plurality of slots are formed along its inner peripheral surface.

In each slot 35, two rectangular electric conductors are inserted as an inner-layer conductor and an outer-layer conductor. These electric conductors are constituted by conductor segments 33. Each conductor 33 is configured into a U-shaped or V-shaped body.

~The stator winding is constituted by numerous conductor segments 33 electrically connected one another. One end of the conductor segment 33 is formed into a turn portion 33c positioned at an axial side of the stator core 25 32, while the other end of the conductor segment 33 is formed into a joint '""portion 33d positioned at the other axial side of the stator core 32. The joint portion 33d is formed by connecting ends of different conductor segments 33.

S* Thus, each conductor segment 33 protrudes from each side of the stator core 32 so as to form the coil end 31. As a result, a plurality of conductor 30 segments 33 are disposed annularly on the stator core 32 so as to form an annular coil end group.

Each conductor segment 33 has a ridgeline portion 33e extending from Page 13 the stator core 32. The ridgeline portions 33e are inclined in opposite directions in the outer and inner layers. A predetermined clearance is provided between adjacent conductor segments 33 at the axial sides of the stator to secure sufficient electrical insulation.

This coil end 31 opposes to the disk portion 72 of the pole core 7 of the rotor 3. An insulating film for each conductor segment 33 can be optionally provided.

The insulator 34, as shown in Fig. 4, has an S-shaped configuration to provide electrical insulation between the stator core 32 and the conductor segments 33 as well as between adjacent conductor segments 33 in each slot.

Each toothed front end portion of the stator core 32 is hardened during a machining process, such as a bending process, when the stator core 32 is manufactured or after the conductor segments 33 are inserted.

The above-described stator winding is a three-phase winding consisting of X, Y and Z phases. One winding end 33f of each phase extends in the axial direction and is directly and electrically connected to an electrode portion 53 of a rectifier element 52 of the rectifier'5 by fusing welding etc. the winding end 33f is provided with a portion 33g having a reduced cross section to absorb vibrations and realize a moderate transmission of a force.

As shown in Fig. 22, the other end of each phase is electrically connected to a neutral point 33k of three phases directly or via a conductor.

A manufacturing method for the stator winding is explained hereinafter.

As shown in Fig. 3, each conductor segment 33 is configured into a U-shaped body having an inner-layer conductor portion 33a, an outer-layer conductor portion 33b, and a turn portion 33c. Each segment 33 is made of a copper plate which is bent and pressed into substantially a U-shaped configuration.

A plurality of conductor segments 33 are arrayed in such a manner that .their turn portions 33c are positioned at the same axial side with respect to the stator core 32. As shown in Fig. 4, the outer-layer conductor portion 33b 30 and the inner-layer conductor portion 33a are inserted into a corresponding slot 35 and arrayed in the depth direction of the slot 35. The outer-layer conductor portion 33b positions adjacent to a closed end of the slot, while the Page 14 Page 14 inner-layer conductor portion 33a positions adjacent to an opening of the slot.

Each slot 35 has parallel side surfaces. Each electric conductor is press fitted into the slot 35 in such a manner that both side surfaces of respective electric conductors confront with corresponding side surfaces of the slot 35 via the insulator 34.

On the other hand, end portions of the plurality of conductor segments 33 are positioned at the other axial end of the stator core 32. These end portions constitute the projecting inner and outer layers. Thereafter, the inner and outer layer are bent in opposite direction in the circumferential direction as shown in and of Fig. 5. The bent inner and outer layers correspond to a predetermined slot number. Thereafter, ends of conductor segments 33 of different layers are connected so as to constitute the joint portion 33d. To secure sufficient electric conduction, the joint portion 33d can be formed by ultrasonic welding, arc welding, brazing etc.

In this embodiment, the rotor magnetic pole number is set to 16. The slot number of the stator core 32 is set to 96. The stator winding constitutes a three-phase winding.

The stator has an outer diameter of 4) 130 mm and an inner diameter of 4) 102 mrm. The laminated thickness of the stator core 23 is 34 mm. The stator core 23 consists of numerous SPCC plate members each having a thickness of 0.5 mm stacked and fixed by laser welding etc. The slots are provided at regular pitches of 3.750 corresponding to an electrical angle pitch of 300. Each slot has substantially rectangular shape having parallel side surfaces. The width between side surfaces is 1. 8 mm. The depth is 10 mm.

The back thickness is 3.5 mm. The opening width is 0.8 mm. The radial thickness of the toothed front end portion is set to 0.5 mm.

The size of the conductor inserted in the slot is 1.6 mm in thickness and 4.5 mm in width. A corner of the conductor is curved by an R of 0.6 mm or less. The insulator 34, having a thickness of approximately 100 pgm, is 30 interposed between the slot and each conductor.

*..."Details of the wiring connection will be explained with reference to Figs. 6, 7 and 8. Each crossover portion shown at the lower side of Fig. 6 or Page Page 1 7 corresponds to the segment turn portion 33c. The upper side corresponds to the joint portion 33d. In the drawings, a solid line represents the inner-layer conductor while an alternate long and short dash line represents the outerlayer conductor.

First, an X phase of the three-phase winding will be explained. A plurality of slots (designated by slot numbers #10, #16, and #94), arrayed at equal intervals of six slots from the starting slot cooperatively constitute a first slot group. A plurality of neighboring slots (designated by slot numbers #11, #17, and arrayed at equal intervals of six slots from the starting slot cooperatively constitute a second slot group.

A first winding is constituted by a plurality of conductor segments 33 accommodated in the first slot group. The first winding comprises two wavy winding portions. A second winding is constituted by a plurality of conductor segments 33 accommodated in the second slot group. The second winding comprises two wavy winding portions.

The first winding and the second winding are serially connected via two joint portions 102 and another joint portion 103. The two wavy winding portions of the second winding are reversed at the joint portion 103 and serially connected. And, to their both ehnds, the wavy winding portions of the first winding are serially connected via the joint portions 102, respectively.

Two ends of the first winding are extracted as winding ends X and X', respectively.

The joint portion 102 connects an inner-layer electric conductor and an outer-layer electric conductor accommodated in two slots spaced at an interval of 5 slots. The joint portion 103 connects the same layer electric conductors accommodated in two slots spaced at an interval of 6 slots.

As a result, the X phase is constituted by the first winding and the second winding which are serially connected and mutually phase shifted by a 300 electric angle. As the number of the conductors per slot for the first 30 winding is 2T (turns) and the second winding is 2T, a resulting stator winding is 4T. The remaining Y phase and Z phase are formed in the same manner, so as to constitute a start-connected winding arrangement of the three phases 16 Page 16 mutually phase shifted at electric angle pitches of 1200, as shown in Fig. 8.

According to the stator winding shown in Figs. 5, 6 and 7, the turn portions 33c of the conductor segments 33 are disposed at one end face of the stator core 32. The winding end 33f extends from the other end face of the stator core 32 and is connected to the rectifier Function and Effect of Embodiment According to the above-described arrangement, the ridgeline portions 33e of the plurality of inner-layer conductor segments 33 are inclined in the same direction. The ridgeline portions 33e of the plurality of outer-layer conductor segments 33 are inclined in the same direction. This is advantageous in that the multi-phase stator winding can be arranged without causing any interference at the coil end. Thus, a space factor of the electric conductor in each slot can be improved. This leads to a higher output. An appropriate clearance is provided between neighboring conductors at the coil end for assuring electric insulation between the conductors. Provision of such a clearance makes it possible to greatly suppress the temperature increase.

Especially, an internal fan 11 is provided at an axial end of a Lundel-type rotor. The outlet holes 43 and 44, each serving as a ventilation hole, are provided on the frame 4 so as to oppose to a outer peripheral side of the coil end 31. This arrangement brings an extreme reduction in the flow resistance of the cooling air. Thus, the cooling air can smoothly pass through the coil end and reach the outer peripheral portion of the frame. The cooling ability can be greatly improved.

Furthermore, adjacent slots can be serially connected for the stator winding. This reduces the number of conductors per slot, making it easy to secure an adequate clearance between conductors at the coil end.

Furthermore, it is easy to obtain the T number required for an automotive alternator.

30 The number of slots is three times the poler number of the rotor when the stator is designed according to a conventional winding method. In this case, none of possible winding methods makes it possible to obtain a T Page 17 number exceeding the number of electric conductors in a slot. In general, automotive alternators have a rated power output of 0.5 to 2.5 kW. When this power output is required at a minimum engine rotational region, the T number of the stator must be at least 3T for a predetermined physical sized alternator installable in an automotive vehicle.

If a designed stator T number is smaller than this value, no power output will be obtained in a low-speed region as indicated by a dotted line in Fig. 9 while a higher power output will be obtained in a limited range of a high-speed region. Such output characteristics will not suit for an automotive alternator.

For example, according to the conventional winding method, the slot number is three times the poler number. It is assumed that the conductor number per slot is two and the T number of the stator winding is 2T. A solid line shown in Fig. 9 represents a power output characteristics of the present embodiment in comparison with the dotted line representing the conventional power output characteristics. As apparent from the graph, the conventional power output characteristics is disadvantageous in that the power output is considerably lowered in the range of idling rotations which is frequently used during the driving operation of automotive vehicles. Thus, the conventional power output characteristics is not applicable to the automotive alternator.

Thus, the conductor number per. slot is inevitably increased. This will significantly reduce an clearance between neighboring conductors at the coil end, when each conductor has a same cross-sectional area. The cooling ability of the cooling air is worsened. As the space factor in each slot is 25 increased, a required man-hour is increased in the assembling of the S" conductors to the stator core. This will increase the manufacturing costs. It may be possible to increase the T number by reducing the cross section of each conductor. However, this will result in a serious reduction in the power output due to an increase in the impedance of the winding.

30 On the other hand, according to the present embodiment, the slot number is equal to or more than three times the pole number and some of the conductors of adjacent slots are serially connected. Thus, the conductor Page 18 number per slot can be minimized to two which is a minimum value. This arrangement effectively provides sufficient clearances at the coil end, thus allowing a satisfactory amount of cooling air to pass the coil end. The space factor in each slot can be improved without increasing the manufacturing costs. An output required for an automotive vehicle can obtained even in a low-speed region.

Furthermore, according to the above-described embodiment, first and second windings are serial connected with a phase difference equivalent to an electric angle 300. This arrangement is advantageous in that a magnetomotive pulsation force can be reduced. This will greatly reduce the magnetic noises.

Furthermore, according to the winding connection shown in Figs. 6 and 7, the inner-layer conductor and the outer-layer conductor are arranged in a two-layer construction and alternately connected. As a result, the length of the crossover portion is the same in each phase. This equalizes the electric resistance values of different phase windings. In addition, as conventionally known, the inductance of the stator winding is differentiated depending on the position in the slot. According to the above-described embodiment, the position of the inner-layer conductors and the outer-layer conductors is the same in each slot. Thus, the inductance can be unified in each slot. The local heat generation can be eliminated.

**"The coil end height can be reduced remarkably. As a result, the resistance value can be reduced to approximately a half compared with a conventional stator winding. This makes it possible to reduce the impedance, realizing both compactness and high power. Due to suppression of heat generation, temperature is reduced and high efficiency can be attained.

Furthermore, the reduction of the coil end height results in a reduced axial length of the stator 2. As a result, a round corner of the frame can be enlarged. As a result, it becomes possible to provide a round automotive 30 alternator which is capable of improving the mechanical rigidity. This is effective to reduce a possibility of causing any interference with other components when the alternator is installed in an automotive vehicle.

.g**e Page 19 Furthermore, the cooling ability can be greatly improved at the coil end. This brings a downsizing of the fan. Furthermore, according to the arrangement of the above-described the coil end portion, the surface roughness can be smoothed and a uniform repetitive pattern is formed. And, the coil end portion allows the cooling air to pass inside thereof. Thus, the fan noises caused by the cooling air can be greatly reduced.

Furthermore, the winding end 33f extends from a side opposed to the turn portion 33c of the conductor segment 33. Thus, the turn portions 33c are formed into the same configuration. Thus, the straight portion other than the turn portion 33c of each segment can be flexibly changed in length for a connection of the winding end 33f or for a connection between the joint portions 102 and 103. In other words, only one thing required in the manufacturing of the conductor segments 33 is to change the lengths of the straight portions. This greatly reduces the production man-hour. The cost for the manufacturing facility can be reduced.

Moreover, the formation of the conductor into the rectangular shape realizes a high space factor. The conductor segment can be fabricated by using a press machine etc. This significantly reduces the material and machining costs. Furthermore, due to an increase of a confronting area between the electric conductors and the stator core, improved heat transfer is realized between the electric conductors and the stator core. Accordingly, the temperature of each electric conductor can be further reduced. The overall rigidity of the stator is increased. As-a result, the magnetic noises can be reduced. Furthermore, due to the rigidity of each electric conductor, 25 maintaining a controlled clearance between the coils is easily done. This makes it possible to eliminate an insulating film for each conductor, as well as removal of a fixing member for the conductors. Accordingly, it becomes 9 S 9• possible to provide an alternator excellent in reliability and low in cost.

Furthermore, improvement of the rigidity at the winding end portion may 30 abolish a conventionally used terminal base for the rectifier. Therefore, it S. becomes possible to directly connect it to the rectifier element 52. This is effective to reduce the costs.

Page The two inner and outer layers are accommodated in each slot by using a single electric conductor. This simplifies the installation. A wire connecting portion is provided at only one portion in the radial direction, without causing any overlap with other wire connecting portion. This is effective to simplify the welding operation etc. The productivity can be improved. In other words, it becomes possible to provide an alternator at a low cost. As only one set of rectifier is arranged, electric components can be simplified. This contributes the cost reduction.

Furthermore, an iron member can be used for the cooling fan of the Lundel-type rotor. This improves the durability in the high-speed condition compared with a salient rotor. According to the salient rotor, magnetic poles are disposed on an axial end face. A member provided at the axial end face must be a non-magnetic material, such as aluminum or a resin, for preventing short-circuit of the magnetic flux. Due to excellent durability in a high-speed region, a pulley ratio can be improved so as to increase the rotational speed of a rotor at an idle condition. This improves the output at the idling condition. Furthermore, material or machining costs for a fan can be reduced.

Furthermore, a cheaper fusing welding can be adopted as a means for connecting the pole core. This is effective to reduce the manufacturing costs.

Second Embodiment Figs. 10 to 12 cooperatively show a second embodiment. The turn portion 33c of the conductor segment 33, shown in the first embodiment, is provided at-one side surface of the stator core 2. However, according to the 25 second embodiment, the conductor segment is separated into two conductor segments without providing the turn portion 33c. Thus, the joint portions are provided at both axial sides of the stator core 32.

As shown in Fig. 11, the conductor segment 33 comprises an internal conductor 33h serving as a straight portion inserted in the slot and external 30 conductors 33i serving as straight portions extend from the both ends of the internal conductor in the axial direction of the stator core 32. The external conductor 33i has an angle and a length for surrounding a distance equivalent Page 21 to approximately a half of a N-and-S magnetic pole pitch. Each external conductor 33i constitutes the ridgeline portion of the coil end 31 as shown in Fig. 10. A plurality of conductor segments 33 are inserted in the corresponding slots so that the ridgeline portions 33i of the inner and outer layers are inclined in opposed directions. The stator core 32 is shown in (A) or of Fig. 12. Each toothed core end 32a is formed into an U-shaped or J-shaped configuration. After a plurality of conductor segments 33 are inserted in a corresponding slot, each toothed core end 32a is deformed plastically, for example, by pushing it in the radial direction using a machining tool so as to close the slot opening formed at an inner periphery of the slot. With this arrangement, it becomes possible to insert the conductor segments 33 from the radially inward direction. The processing of the conductor segments can be performed beforehand. This simplifies the installation.

Furthermore, after the conductor segments are inserted in the slot, it is possible to deform the conductor segments by depressing the conductor segments from the radially inward direction so that the conductor segments fit to the configuration of the slot. This is effective to realize a high space factor. Moreover, the toothed core end is hardened through the plastic deformation. This is effective to prevent the toothed core end from being deformed by the springback of the conductor segment 33. Although the present embodiment processes the conductor segment 33 beforehand, it is possible to perform the bending operation after the conductor segment 33 is inserted in the slot.

Third Embodiment The above-described first and second embodiments have a pair of inner-layer and outer-layer electric conductors. That is, the electric conductor number in each slot is 2T. However, it is possible to provide electric *o* 30 conductors of two pairs or more by repeating the above-described insertion process of the conductor segments. In this case, as shown in Fig. 13, the interference between the different phases at the coil end portions can be Page 22 avoided in the same manner as in the first embodiment. Thus, the higher space factor, improved cooling efficiency and noise reduction can be attained in the same manner as in the above-described embodiments. Furthermore, the electric conductor number per slot is increased. This is advantageous in that, even when the engine is operated in a lower-speed region, a sufficient amount of electric power is generated. Thus, it becomes possible to increase a generated power output amount at the lower-speed region.

Fig. 14 shows an insulator which is configured for the two pairs of inner-layer and outer-layer electric conductors, corresponding to a conductor number per slot is 4T.

Furthermore, when the inner-layer and outer-layer electric conductors of two pairs or more are provided, the T number is arbitrarily realized by changing the settings for the slot number, wire connecting portions etc.

Fourth Embodiment According to the above-described first to third embodiments, the windings of slot groups mutually phase shifted by a 300 electric angle are connected in series to increase the T number per slot. This is also effective in view of noise reduction, because the 6 times order components of the polar pair number, serving as main components of the magnetic noises, can be canceled. In short, a summed-up AC output is generated from these two Swindings.

On the other hand, Figs. 15 and 16 are developments showing the .:.stator winding of the fourth embodiment. Fig. 17 shows a circuit diagram of 25 the fourth embodiment. Two sets of three-phase windings mutually phase shifted by a 300 electric angle are rectified by rectifiers, respectively. The rectified outputs are combined to generate a summed-up DC output.

Details of the wiring connection will be explained with reference to Figs. 15, 16 and 17. Each crossover portion shown at the lower side of Fig.

30 15 or 16 corresponds to the segment turn portion 33c. The upper side corresponds to the joint portion 33d. In the drawings, a solid line represents the inner-layer conductor while an alternate long and short dash line Page 23 represents the outer-layer conductor.

First, first and second windings of an X phase will be explained. A plurality of slots (designated by slot numbers #10, #16, and #94), arrayed at equal intervals of six slots from starting slot cooperatively constitute a first slot group. A plurality of neighboring slots (designated by slot numbers #11, #17, and arrayed at equal intervals of six slots from the starting slot cooperatively constitute a second slot group.

The first winding extends throughout the first conductor group from a winding end XI to another winding end Xl'. The first winding comprises two wavy winding portions serially connected at an inversion joint portion interposed between the winding ends XI and XI' shown in Fig. 15. The second winding extends throughout the second conductor group from a winding end X2 to another winding end X2' shown in Fig. 16. The second winding is arranged in the same manner as the first winding.

Furthermore, the Y phase and Z phase are formed in the same manner at the intervals of 1200 electric angle pitches, so as to form the first and second windings in each phase.

Fig. 17 shows a winding arrangement connecting these six windings.

A total of three, Y- and Z-phase, first windings are connected to constitute a star-connected winding arrangement, and are connected to a first rectifier. A total of three, Y- and Z-phase, second windings are connected to constitute a star-connected winding arrangement, and are connected to a second rectifier. The first and second rectifiers produce DC outputs which are summed up.

With this arrangement, it becomes possible to produce a summed-up DC output from 2T three-phase windings. This possibly improves the power shortage in the engine low-rotational region. If the fourth embodiment is combined with the above-described third embodiment which comprises the inner-layer and outer-layer electric conductors of two pairs or more, the T 30 number per slot can be increased to 4T or more. This solves the generated power shortage in the low-rotational region. Moreover, this arrangement is advantageous in that the serial connection of mutually phase shifted windings Page 24 is no longer required. This makes it possible to equalize the configuration of the conductor segments. The production efficiency in the manufacturing of the conductor segments can be further improved. Needless to say, it is possible to cancel the 6 times order components of the polar pair number serving as main components of the magnetic noises.

Other Embodiments According to the above-described first embodiment, the conductor segments are connected at only one axial side surface of the stator 2. It is possible to connect the conductor segments at the both axial sides of the stator 2. For example, the turn portions of a plurality of conductor segments can be separately provided at the both axial end portions of the stator core 32.

In this case, the joint pitch can be widened. Thus, the connecting process, such as the welding operation, can be simplified.

The stator core 32 shown in Fig. 12 employed in the second embodiment can be combined with the conductor segments 33 shown in Fig.

3 employed in the first embodiment.

When the stator core 32 shown in Fig. 12 is used, the conductor segments are inserted into corresponding slots and then the slots are successively plastically deformed so as to improve the production efficiency remarkably.

The electric conductor may be a rectangular conductor consisting of a plurality of wires.

:2.*The above-described embodiments use the electric conductors made 25 of copper. However, it is possible to use aluminum or iron conductors. When these materials are used, the material costs can be reduced. The production process can be simplified by using molding or die casting.

The rectangular electric conductors used in the above-described embodiments can be replaced by round electric conductors. It is also possible 30 to use complex conductors comprising both a rectangular conductor portion and a round conductor portion. For example, the rectangular conductor portion may be disposed in the slot while the round conductor portion may Page be disposed outside the slot. This arrangement is advantageous in that the space factor in the slot can be increased, Furthermore, the cooling ability can be increased. On the contrary, the round conductor portion may be disposed in the slot while the rectangular conductor portion may be disposed outside the slot. This arrangement is advantageous in that a sufficient clearance can be provided between electric conductors at the coil end. The flow resistance of the cooling air is reduced. The cooling ability can be improved greatly.

Preferably, the rectangular electric conductor may have a flattened cross section.

It is preferable to cover each conductor segment 33 by an insulating film, so that a U-shaped insulator is disposed along the inner wall of the slot.

In this case, the insulator configuration is simplified. It is further possible to eliminate the insulator by applying appropriate insulation processing to the stator core 32. In this case, it becomes possible to avoid insulation defect due to dislocation of the insulator during the insertion of each conductor segment 33 into the slot.

The stator winding may be a multi-phase winding having phases more than three. Even in the multi-phase winding, the winding of the stator core 32 can be formed regularly. The winding structure is not complicated. Having the phases more than three is effective to reduce the noise and the ripple of rectified voltage.

The stator winding can be constituted by a triangular winding arrangement. The winding type should be determined properly according to a required performance of the generated power for an automotive vehicle.

25 It is possible to use a rotor having no magnet, or a rotor having only magnetization by a magnet.

It is possible to provide cooling fans at the both end faces of the rotor, as shown in Fig. 18. According to this arrangement, another cooling fan 12 is provided at a front end side of the rotor. This arrangement improves the 30 cooling characteristics. According to the Lundel-type rotor causing wind at a disk portion of the pole core, a satisfactory cooling ability can be attained by using only one cooling fan 11 shown in Fig. 1. However, providing the Page 26 cooling fans at the both ends of the rotor is effective to increase the cooling ability and reduce the size of the automotive alternator when the same power output is demanded.

Furthermore, the arrangement shown in Fig. 19 can be adopted. An end face of the rotor 3, not provided with the cooling fan, confronts an inner wall surface 45 of the outer peripheral portion of the air inlet hole 41 of the frame 4. When the disk portion 72 of the pole core 7 functions as a fan, the inner wall surface 45 can serve as a fan shroud. The fan ability at the disk portion 72 is increased. Accordingly, compared with the above-described arrangement where the cooling fans are provided at the both ends of the rotor, it becomes possible to attain a comparable cooling ability without increasing the number of parts and man-hour. Furthermore, the size is reduced.

As shown in Fig. 23, it is possible to provide the winding end 33f at the same side as the turn portions 33c. This arrangement is advantageous because the winding end 33f does not interfere with a welding operation performed at the joint portion side. Furthermore, the production process can be simplified due to a repetitive connection of the same pattern.

According to the above-described embodiments, the slot number is six times as large as the pole number. Some of electric conductors accommodated in two adjacent slots are connected in series at an appropriate portion to realize a series of windings of 4T. This may be referred to as a three-phase, double slot, serial winding. However, it is preferable to set the slot number nine times as large as the poler number. When the electric conductors accommodated in adjacent three slots are connected in series at appropriate portions, a 6T arrangement is realized. This may be referred to as a three-phase, triple slot, serial winding.. Furthermore, it is possible to realize an odd number turn, 5T, arrangement by connecting the conductors in parallel at an appropriate slot. It is needless to say that the T number can be further increased by increasing the slot number.

30 The number of slots provided in the stator core 32 can be increased by 1 from the above-described double slot arrangement. For example, a total of 97 slots are formed in the stator core 32. Figs. 20 and 21 are developments Page 27 showing detailed winding connections. In the drawing, the solid line represents an inner-layer electric conductor, while the alternate long and short dash line represents an outer-layer electric conductor. According to this arrangement, the shape, especially the height, of joint portions 104 and 105 can be equalized with that of other joint portions of the coil end. According to the winding arrangement shown in Figs. 6 and 7, the joint portions 102 and 103 are different in height from other joint portions of the coil end. This requires electric conductors different in shape. The connecting process will be complicated.

The joint portion 104 connects the electric conductors constituting different layers of adjacent slots. The joint portion 104 is identical in the inclination and height as other joint portions of the coil end. This is advantageous in that the length of each straight portion other than the turn portion can be equalized in the fabrication of the U-shaped segments. Thus, the process for producing the segments can be simplified. The joint portion 105 connects the electric conductors constituting the same layer. The joint portion 105 can be configured along an ordinary repetitive pattern. The winding connecting process can be simplified.

In this arrangement, it is possible to dispose the turn portions of the Ushaped conductor segments at the same side as the winding end X and others shown in Figs. 20 and 21. The spreads of the turn portions are all unified to a 6-slot pitch. This results in a simplified production process for the segments.

25 Industrial Utilization As described in the foregoing description, the present invention S: eliminates the interference at the coil end, increases the space factor of the stator winding, and improves the power output. Furthermore, as the inner and outer conductors are connected in series, both the conductor length and the leakage inductance of each phase winding depending on the position in the slot can be unified. Accordingly, the currents flowing across the coils can be equalized. The heat generation amount in each phase can be equalized. It Page 28 Page 29 becomes possible to eliminate the local heat generation at the stator winding as well as the unbalance of the magnetic motive force. The temperature reduction and the noise reduction can be realized. Furthermore, the stator winding is serially connected between adjacent slots. The conductor number per slot can be reduced so as to secure sufficient clearances between the conductors at the coil end. It becomes possible to obtain a turn number required for generating a satisfactory power output as an automotive generator at a low-speed region. Accordingly, the present invention can be utilized for alternators of automotive vehicles and contribute to the realization of their downsizing and power-up.

In the claims that follow and in the summary of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprising" is used in the sense of "including", i.e. the features specified may be associated with further features in various embodiments of the invention.

S* e

Claims (27)

1. An alternator for an automotive vehicle, comprising: a field rotor with N and S poles formed alternately in a circumferential direction, a stator including a stator core disposed in a confronting relationship with said rotor and a multi-phase stator winding associated with said stator core, and a frame supporting said rotor and said stator, wherein said field rotor comprises a Lundel-type core having a plurality of hooked magnetic poles serving as said N and S poles, said stator core comprises laminated cores formed with a plurality of slots extending across laminated plates, said multi-phase stator winding comprises a plurality of conductor segments, said plurality of conductor segments constitute at 20 least a first pair of conductors including an inner-layer conductor and an outer-layer conductor and a second pair of :conductors including an inner layer conductor and an outer ."*layer conductor, said first and second pairs of conductors are arrayed in a line in only a depth direction of each slot, and said conductor segments are insulated from each other in each slot, ooo. said plurality of conductor segments are partly S"disposed out of said slots so as to extend from an end face oooof said stator core and form a coil end having a F 30 predetermined connecting pattern according to which an inner-layer conductor and an outer-layer conductor of each pair of conductors disposed in different slots spaced at predetermined intervals corresponding to a magnetic pole pitch of said field rotor are serially connected, thereby forming a coil end group chiefly repeating said connecting pattern at the end face of said stator core, and said plurality of conductor segments of said coil end extend in a direction intersectional with a flow direction 30a of cooling air introduced in said frame, so that the cooling air can flow across said conductor segments of said coil end.

2. The alternator for an automotive vehicle in accordance with claim 1, wherein said multi-phase stator winding has a winding end as an output terminal. said stator and said rotor cooperatively generate a voltage equal to or larger than 15V from said winding end in an idling speed region of an engine which drives said rotor. U U U. U U U U U U U U U c oooo U *.U U 31

3. The alternator for an automotive vehicle in accordance with claim 1 or 2, wherein said Lundel-type core is defined by the following relationship L1 L2 where L1 represents an outer diameter of the hooked magnetic pole of said Lundel-type rotor, and L2 represents a length in a rotational axis of said Lundel- type rotor.

4. The alternator for an automotive vehicle in accordance with any one of claims 1 through 3, wherein all of conductor segments electrically insulated in said slots are spatially separated at the coil end formed at an axial end portion of said stator core. The alternator for an automotive vehicle in accordance with any one of claims 1 through 4, wherein toothed core ends are positioned at both sides of said slot, and at least part of said toothed core is plastically deformed to form an opening of said slot having a width narrower than a distance between inner walls of said slot, said opening of said slot being provided at an inner peripheral side of said slot.

6. The alternator for an automotive vehicle in accordance with any one of claims 1 through 5, wherein each conductor segment is formed into a rectangular shape fitting to the configuration of a corresponding slot at a portion inserted in said slot.

7. The alternator for an automotive vehicle in accordance with any one S of claims 1 through 6, wherein said conductor segments are naked metallic members, an electrical insulating material is interposed between said plurality of conductor segments inserted in said slot as well as between said plurality of conductor segments and inner walls of said slot for assuring electric insulation, and S"said plurality of conductor segments are spatially separated at a portion outside said slot. 32

8. The alternator for an automotive vehicle in accordance with any one of claims 1 thtough 7, wherein an overall axial length of said stator comprising said stator core and conductor segments accommodated in said slots is equal to or shorter than an overall axial length of said Lundel-type rotor.

9. The alternator for an automotive vehicle in accordance with any one of claims 1 through 8, wherein said conductor segment is formed at least partly into a flat configuration at a portion outside said slot. The alternator for an automotive vehicle in accordance with any one of claims 1 through 9, wherein a magnet is interposed between magnetic poles of said field rotor so that said stator is exposed to a magnet flux in addition to a field flux.

11. The alternator for an automotive vehicle in accordance with any one of claims 1 through 10, wherein said plurality of conductor segments disposed at said coil end are exposed to said cooling air at substantially entire surfaces thereof.

12. The alternator for an automotive vehicle in accordance with any one of claims 1 through 11, wherein said coil end group is formed at each axial end portion of said stator core, and two cooling air passages are formed in said *frame so as to correspond to respective coil end groups.

13. The alternator for an automotive vehicle in accordance with any one of claims 1 through 12, wherein a ventilating means is provided for causing a flow of cooling air in said frame.

14. The alternator for an automotive vehicle in accordance with claim 13, wherein said ventilation means is provided at an axial end portion of said field rotor for causing a flow of cooling air directing a centrifugal outer direction in accordance with the rotation of said field rotor, so that the cooling air can flow across said conductor segments. 33 The alternator for an automotive vehicle in accordance with claim 14, wherein said ventilation means is provided at both axial end portions of said field rotor.

16. The alternator for an automotive vehicle in accordance with claim 14 or 15, wherein said ventilation means is a fan having a plurality of blades.

17. The alternator for an automotive vehicle in accordance with any one of claims 13 through 16, wherein said Lundel-type core has a configuration corresponding to said plurality of hooked magnetic poles, so that said Lundel- type core is capable of serving as said ventilation means.

18. The alternator for an automotive vehicle in accordance with claim 17, wherein an axial end portion of said Lundel-type core is disposed in an adjacent and confronting relationship to an inner wall surface of said frame.

19. The alternator for an automotive vehicle in accordance with any one of claims 13 through 18, wherein said frame is formed with an inlet hole for said ventilation means, said inlet hole faces to an installation end of a pulley which drives said field rotor, and an outermost diameter of said inlet hole is smaller than an outermost diameter of said pulley. The alternator for an automotive vehicle in accordance with an one of claims 1 through 19, wherein said frame is formed with a ventilation hole at across said electric conductors. S 21. The alternator for an automotive vehicle in accordance with any one of claims 1 through 19, wherein said coil end is formed by connecting end portions of said conductor segments extending from said slots, and the end portion of one conductor segment has an angle and a length sufficient for surrounding approximately a half of said magnetic pole pitch.

22. The alternator for an automotive vehicle in accordance with claim 21, 34 wherein each conductor segment is an U-shaped segment having two straight portions accommodated in different slots, respectively, an end portion of a first U-shaped segment and an end portion of a second U-shaped segment are connected according to said connecting pattern so as to form said coil end.

23. The alternator for an automotive vehicle in accordance with claim 22, wherein a turn portion of said U-shaped conductor segment protrudes from one end face of said stator core in the axial direction so that the turn portions of said U-shaped conductor segments are spaced from each other to form a first coil end group, and open ends of said U-shaped conductor segment protrude from the other end face of said stator core in the axial direction and are connected in a predetermined connecting pattern so that the coil ends are spaced from each other to form a second coil end group.

24. The alternator for an automotive vehicle in accordance with claim 21, wherein each conductor segment has two end portions protruding from both ends .*of a corresponding slot, one coil end is formed at one end of said stator core by connecting one end portion of a first segment and one end portion of a second segment according to said connecting pattern, and the other coil end is formed at the other end of said stator core by connecting the other end portion of said first segment and the other end portion of said second segment according to said connecting pattern. The alternator for an automotive vehicle in accordance with claim 24, 0o o GS o 35 wherein a sum of circumferential lengths of both end portions of said conductor segment corresponds to said magnetic pole pitch.

26. The alternator for an automotive vehicle in accordance with any one of claims 1 through 25, wherein a rectifying element is provided, and part of said conductor segment is directly connected to an electrode of said rectifying element.

27. The alternator for an automotive vehicle in accordance with claim 26, wherein said conductor segment connected to the electrode of said rectifying element has an easily deformable portion between said stator and the electrode of said rectifying element.

28. The alternator for an automotive vehicle in accordance with claim 22 or 23, wherein a rectifier is disposed at a same side as the turn portion of said U-shaped segment and connected to the winding end of said stator winding. .29. The alternator for an automotive vehicle in accordance with claim 22 or 23, wherein a rectifier is disposed at a side opposed to the turn portion of S. said U-shaped segment and connected to the winding end of said stator winding.

30. The alternator for an automotive vehicle in accordance with any one S. of claims 1 through 29, wherein said stator comprises extended wiring portions mutually short-circuited for constituting a neutral point. .31. The alternator for an automotive vehicle in accordance with any one of claims 22, 23, 28 or 29, wherein said U-shaped segments are electric conductors each having an elongated rectangular cross section, and a longitudinal direction of said cross section is disposed along a radial direction at said coil end. 35a

32. The alternator for an automatic vehicle in accordance with any one of claims 1 through 30, wherein said plurality of conductor segments are connected with other conductor segments at said coil end group to form a plurality of joint portions, and said plurality of joint portions are arranged into multiple loops and mutually spaced in both a circumferential direction and a radial direction in said coil-end group. *00 0 0 0 00* 0 0 0.0. 0 0 9 0000 9 0 0000 0 0 9 0 09 0 0*9 9 36

33. An alternator for an automotive vehicle, comprising: a field rotor with N and S poles formed alternately in a circumferential direction, a stator including a stator core disposed in a confronting relationship with said rotor and a multi-phase stator winding associated with said stator core, and a frame supporting said rotor and said stator, wherein said stator core has a plurality of slots for accommodating said multi-phase stator winding, said multi-phase stator winding comprises a plurality of conductor segments, said plurality of conductor segments constitute at least two pairs of conductor segments arrayed in a line in only a depth direction of each slot, and said conductor segments are insulated from each other in each slot, said plurality of conductor segments are arranged such that said conductor segments of each pair of conductor segments disposed in different slots spaced at 20 predetermined intervals corresponding to a magnetic pole pitch of said field rotor are similarly connected, said plurality of conductor segments are partly disposed out of said slots so as to extend from an end face SC of said stator core and form a coil end, said plurality of conductor segments are partly disposed out of said slots so as to extend from an end face of said stator core and form a coil end, said plurality of conductor segments are mutually connected so as to form a plurality of joint portions, and 30 said plurality of joint portions are arranged into multiple loops and mutually spaced in both a circumferential direction and a radial direction.

34. The alternator for an automotive vehicle in accordance with claim 33, wherein said plurality of joint portions are disposed so as to form a two-turn loops. 37 An alternator for an automotive vehicle, comprising: a field rotor with N and S poles formed alternately in a circumferential direction, a stator including a stator core disposed in a confronting relationship with said rotor and a multi-phase stator winding associated with said stator core, and a frame supporting said rotor and said stator, wherein said field rotor comprises a Lundel-type core having a plurality of hooked magnetic poles serving as said N and S poles, said stator core comprises laminated cores formed with a plurality of slots extending across laminated plates, said multi-phase stator winding comprises a plurality of conductor segments, said plurality of conductor segments constitute at least a first pair of conductors including an inner-layer conductor and an outer-layer conductor and a second pair of 20 conductors including an inner layer conductor and an outer layer conductor, said first and second pair of conductors are arrayed in a line in only a depth direction of each :**slot, and said conductor segments are insulated from each other in each slot, said plurality of conductor segments are partly disposed out of said slots so as to extend from an end face of said stator core and from a coil end having a predetermined connecting pattern according to which an inner layer conductor and an outer layer conductor of each 30 pair of conductors disposed in different slots spaced at predetermined intervals corresponding to a magnetic pole pitch of said field rotor are serially connected, thereby forming a coil end group chiefly repeating said connecting pattern at the end face of said stator core, and two coil ends belonging to two adjacent slots are spaced from each other due to a distance between said two adjacent slots in the circumferential direction.

436. The alternator for an automotive vehicle in )accordance with claim 38 wherein the plurality of conductor segments are arrayed in a radial direction in the same slot with outer extending portions protruding from one end face of said stator core to form the coil ends, and said outer extending portions of said plurality of conductor segments are inclined in the circumferential direction so that the inclined directions of said outer extending portions are opposed each other between two radially adjacent layers. 37. An alternator for an automotive vehicle substantially as herein described with reference to the accompanying drawings in Figures 13 and 14. Dated this 10th day of November 2000 Denso Corporation By their Patent Attorneys GRIFFITH HACK S S OSO *oo S a