Sequentially joined-segment armature and ac machine using same

A sequentially joined segment armature coil is provided which may be employed in an ac machine such as an ac motor or motor generator. The armature coil is equipped with three phase coils each of which is made up of a first and a second phase windings identical in number of turns. This structure permits the number of turns of the armature coil to be changed easily by changing a connection of the first and second phase winding between a series connection and a parallel connection or changing a connection of the phase coils between a star connection and a delta connection. The structure also enables terminal leads of the first and second phase windings of each of the phase coils to be collected and withdrawn outside the ac machine, thus facilitating ease of arrangement of the terminal leads.

BACKGROUND OF THE INVENTION

1. Technical Field of the Invention

The present invention relates generally to a sequentially joined-segment armature and an ac machine using the same which may be employed as a rotary electric machine for automotive vehicles.

2. Background Art

Idle stop systems, as having been employed in automotive vehicles in recent years, are designed to perform frequent engine start-and-stop operations, therefore, use of ac motors is preferable to dc motors with brushes. However, ac motors capable being supplied with a great starting current equivalent to that use in typical dc series-wound motor will be greater in size than typical alternators, thus requiring a large amount of space within an engine compartment of the vehicles or a substantial change in engine layout, which may lead to an increase in weight of the vehicles.

As automotive ac generators, ac machines have been proposed which are equipped with a conductor segment-joined armature made up of U-shaped conductor segments which are disposed within slots formed in a stator core and joined sequentially. For instance, Japanese Patent First Publication Nos. 11-164506 and 2001-169490 disclose such a type of ac machine.

Japanese Patent First Publication No. 2001-169490 (corresponding to U.S. Pat. No. 6,417,592 B2 to Nakamura et al. assigned to the same assignee as that of this application) discloses segment-joined automotive ac generator which is equipped with U-shaped large-sized conductor segments and U-shaped small-sized conductor segments which partially extend through slots arrayed in a stator core in a circumferential direction thereof. Each of the slots has a first, a second, a third, and a fourth layer positions arrayed from inside to outside of the stator core in a radius direction thereof. The large-sized conductor segments each have legs disposed in the first and fourth layer positions of the slots. The small-sized conductor segments each have legs disposed in the second and third layer positions of the slots. A total of four turn coils, two disposed in two of the slots located across one of the slots, are so connected as to cross to joint two of the turn coils in parallel to make phase windings. Specifically, an eight conductor-in-two slot stator coil is taught to double the current permitted to be supplied to the coil without increasing poles.

Japanese Patent First Publication No. 11-164506 teaches a six conductor-in-one slot stator coil which is equipped with U-shaped large-sized conductor segments and U-shaped small-sized conductor segments which partially extend through slots arrayed in the stator core in the circumferential direction thereof. Each of the slots has a first, a second, a third, a fourth, a fifth, and a sixth layer positions arrayed from inside to outside of the stator core in the radius direction thereof. The large-sized conductor segments each have legs disposed in the first and sixth layer positions of the slots. Some of the small-sized conductor segments have legs disposed in the second and third layer position of the slots. The others have legs disposed in the fourth and fifth layer positions of the slots. This structure permits the number of turns of the stator coil to be five times greater than that disclosed in the former publication, thus providing a high-voltage stator coil.

The above described stator coils are designed to fix a wiring pattern or order of joints of the conductor segments. It is, thus, difficult to increase the turns of the stator coil without increasing rotor poles, thereby increasing a difficulty in using the rotary machine with a high-voltage battery in automotive vehicles. Further, increasing a sectional area of the conductor segments results in a difficulty in bending thereof, which increases a difficulty in use of the stator coil with a great current.

Locations where lead wires extend from the parallel-connected phase windings of each of the phase coils are greatly away from each other, thus resulting in an increase in length of the lead wires, which leads to increased resistance and inductance of the lead wires. The increase in length of the lead wires also requires a large amount of space in the rotary machine, thus resulting in an increased length of the rotary machine.

SUMMARY OF THE INVENTION

It is therefore a principal object of the invention to avoid the disadvantages of the prior art.

It is another object of the invention to provide a segment joined-armature and an ac machine using the same which are designed to allow a great current to be supplied to the coil without increasing a difficulty in wiring operations, a sectional area of conductor segments, and the length of the ac machine.

According to one aspect of the invention, there is provided a segment joined armature and an ac machine which may be employed as ac motor or motor-generator for automotive vehicles.

The segment joined armature comprises: (a) an armature core having slots, q(=integer greater than two or more) for each pole in each phase, the slots being arrayed in a circumferential direction of the armature core; and (b) an armature winding made up of m(=integer greater than three or more) phase coils. Each of the phase coils is made up of a first phase winding and a second phase winding which are identical in number of turns and extending in opposite winding directions. Each of the first and second phase windings is made up of at least one wave winding segment and lap winding segments joined alternately. Each of the wave winding segment and the lap winding segments is formed by sequentially joined-conductor segments. Each of the conductor segments includes a substantially V-shaped head portion, a pair of leg portions extending from ends of the head portion, disposed in two of the slots of the armature core located at a given interval away from each other, and a pair of joint end portions extending from ends of the leg portions. s(=integer greater than four or more) of the leg portions are arrayed within each of the slots of the armature core in a radius direction of the armature core. Each of the joint end portions of each of the conductor segments is joined to one of the joint end portions of another of the conductor segments to make each of the first and second phase windings. The wave winding segment is made up of the conductor segments having the leg portions located at an interval away from each other which is greater than or equal to one pole pitch. Each of the lap winding segments is made up of the conductor segments having the leg portions located at an interval away from each other which is less than one pole pitch. An end of the first phase winding and an end of the second phase winding are formed by two of the leg portions of the conductor segments which are disposed adjacent to each other in the radius direction within the same one of the slots of the armature core and which lead to two first terminal leads. The other end of the first phase winding and the other end of the second phase winding are formed by two of the leg portions of the conductor segments which are disposed adjacent to each other in the radius direction within the same one of the slots of the armature core and which lead to two second terminal leads.

The above structure in which each of the phase coils is made up of the first and second phase windings identical in number of turns with each other permits the number of turns of the armature winding to be changed easily by changing a connection of the first and second phase winding between a series connection and a parallel connection or changing a connection of the phase coils between a star connection and a delta connection. The structure also enables the terminal leads of the first and second phase windings of each of the phase coils to be collected and withdrawn outside the ac machine, thus facilitating ease of arrangement of the terminal leads.

In the preferred mode of the invention, four of the leg portions of the conductor segments are arrayed within each of the slots of the armature core as a first, a second, a third, and a fourth layer conductors from inside to outside the armature core in the radius direction of the armature core. Each of the first and second phase windings are broken down into a first and a second group. The first group is made up of the conductor segments having the first and fourth layer conductors separated from each other at a given slot pitch. The second group is made up of the conductor segments having the second and third layer conductors separated from each other at a given slot pitch. Tips of the joint end portions leading to the first layer conductors are joined to tips of the joint end portions leading to the second layer conductors. Tips of the joint end portions leading to the third layer conductors are joined to tips of the joint end portions leading to the fourth layer conductors. The wave winding segment is made up of the conductor segment having the tips of the joint end portions separated from each other at an approximately two pole pitch. Each of the lap winding segments is made up of the conductor segments each having the joint end portions separated from each other at an approximately zero slot pitch. The first and second layer conductors or the third and fourth layer conductors defining ends of the first and second phase windings of each of the phase coils disposed within the same one of the slots lead to paired first terminal leads, respectively. The third and fourth layer conductors or the first and second layer conductors defining other ends of the first and second phase windings of each of the phase coils disposed within the same one of the slots lead to paired second terminal leads, respectively.

The pairs of the first terminal leads of the phase coils are located at an interval away from each other which is equivalent to an electrical angle of 2π/m within an electrical angle range of approximately 2π(m−1). The pairs of the second terminal leads of the phase coils are located at an interval away from each other which is equivalent to an electrical angle of 2π/m within an electrical angle range of approximately 2π(m−1).

The pairs of the second terminal leads form neutral point joint leads which are connected at a neutral point to establish a star-connection of the phase coils.

The first terminal leads of the first and second phase windings of one of the phase coils form input/output lines of a first phase. The first terminal leads of the first and second phase windings of a second one of the phase coils form input/output lines of a second phase. The second terminal leads of the first and second phase windings of the one of the phase coils are connected to the input/output lines of the second phase. The first and second phase windings of each of the phase coils are connected in parallel to each other. The phase coils are connected in a delta form.

Each of the first and second phase windings of each of the phase coils includes a first turn coil made up of the wave winding segment and the lap winding segments to form turns around the armature core, a second turn coil made up of the wave winding segment and the lap winding segments to form turns around the armature core, and an anomaly conductor segment connecting the first and second turn coils in series. The first and second phase windings of each of the phase coils extend in opposite winding directions and are identical electromagnetically with each other.

The anomaly conductor segments of each of the phase coils are disposed adjacent to each other within two of the slots separated from each other at a slot pitch shorter than the slot pitch of the wave winding segment and the lap winding segments by at least one slot pitch.

Locations of interfaces between the first and second terminal leads of each of the phase coils and the conductor segments are defined across the V-shaped head portion of the anomaly conductor segment in a circumferential direction of the armature core.

Each of the first and second phase windings are broken down into a first and a second group. The first group is made up of the conductor segments having the first and fourth layer conductors separated from each other at a given slot pitch which is shorter than a pole pitch by one slot pitch or more. The second group is made up of the conductor segments having the second and third layer conductors separated from each other at a given slot pitch which is shorter than the pole pitch by one slot pitch or more. Tips of the joint end portions leading to the first layer conductors are joined to tips of the joint end portions leading to the second layer conductors. Tips of the joint end portions leading to the third layer conductors are joined to tips of the joint end portions leading to the fourth layer conductors. Each of the first and second phase windings includes a first turn coil, a second turn coil, and an anomaly conductor segment. The first turn coil is made up of the wave winding segment(s) formed by the conductor segment having tips of the joint end portions separated from each other at approximately two pole pitch and the lap winding segment formed by the conductor segments each having tips of the joint end portions separated from each other at approximately one slot pitch. The wave winding segment(s) and the lap winding segments are connected alternately to make turns. The second turn coil made up of the wave winding segment(s) and the lap winding segments connected alternately to make turns extend in the same winding direction as that of the first turn coil. The anomaly conductor segment has legs disposed in two of the slots separated from each other at a pitch different from that of the wave winding segment and the lap winding segments to connect the first turn coil and the second turn coil in series. The first and second phase windings of each of the phase coils are identical with each other electromagnetically and extend in opposite winding directions.

The anomaly conductor segments of each of the phase coils are disposed adjacent to each other within two of the slots separated from each other at a pitch shorter than the pitch of the wave winding segment and the lap winding segments by at least one slot pitch.

The first and second layer conductors or the third and fourth layer conductors defining ends of the first and second phase windings of each of the phase coils disposed within the same one of the slots lead to paired first terminal leads, respectively. The third and fourth layer conductors or the first and second layer conductors defining other ends of the first and second phase windings of each of the phase coils disposed within the same one of the slots lead to paired second terminal leads, respectively. The first terminal leads form input/output lines. The second terminal leads form neutral point joint leads are connected at a neutral point to make a star-connection of the phase coils.

The first terminal leads of the first and second phase windings of one of the phase coils form input/output lines of a first phase. The first terminal leads of the first and second phase windings of a second one of the phase coils form input/output lines of a second phase. The second terminal leads of the first and second phase windings of the one of the phase coils are connected to the input/output lines of the second phase. The first and second phase windings of each of the phase coils are connected in parallel to each other. The phase coils are connected in a delta form.

Locations of interfaces between the first and second terminal leads of each of the phase coils and the conductor segments are defined across the V-shaped head portion of the anomaly conductor segment in the circumferential direction of the armature winding.

Each of the phase coils has a bridging conductor segment extending over the anomaly conductor segment to establish a series connection of the first and second phase windings. The bridging conductor segment includes leg portions disposed within the slots which are defined by the first and third layer conductors or the second and fourth layer conductors. The leg portions of the bridging conductor segment form a trailing one of the leg portions of the conductor segments of the first phase winding and a leading one of the leg portions of the conductor segments of the second phase winding. The leg portions of each of the bridging conductor segments are disposed within two of the slots which are the same as those within which the leg portions of the first and second phase windings of a corresponding one of the phase coils leading to the first and second terminal leads are disposed.

Each of the first and second phase windings may include a first turn coil, a second turn coil, and an anomaly conductor segment. The first turn coil includes first lap winding segments, second lap winding segments, and the wave winding segments which are joined alternately to make turns. The first lap winding segments are made up of ones of the lap winding segments formed by the conductor segments having the joint end portions separated at a joint pitch of approximately ½ slot pitch and the second and third layer conductors separated at a first slot pitch shorter than the pole pitch by one slot pitch or more. The second lap winding segments are made up of ones of the lap winding segments formed by the conductor segments having the joint end portions separated at a joint pitch of approximately ½ slot pitch and the fourth and fifth layer conductors separated at the first slot pitch, and the wave winding segments having the joint end portions separated at a joint pitch that is identical with two pole pitches minus sum of the joint pitches of the first and second lap winding segments and the first and sixth layer conductors separated at the first slot pitch. The second turn coil is made up of winding segments identical with the first lap winding segments and winding segments identical with the second lap winding segments which are connected alternately to make turns oriented in the same winding direction as that of the first turn coil. The anomaly conductor segment has leg portions disposed within two of the slots separated at a slot pitch different from the first slot pitch to establish a series connection of the first and second turn coils. The first and second phase windings of each of the phase coils are identical with each other electromagnetically and extend in opposite winding directions.

The first and second layer conductors disposed adjacent to each other within a same one of the slots belong to the first and second phase windings connected in parallel, respectively. The fifth and sixth layer conductors disposed adjacent to each other within a same one of the slots belong to the first and second phase windings connected in parallel, respectively.

The first and second layer conductors disposed adjacent to each other within a preselected one of the slots lead to an end of each of the phase coils. The fifth and sixth layer conductors disposed adjacent to each other within a preselected one of the slots lead to the other end of each of the phase coils. The phase coils are connected to make a star connection winding.

The first and second layer conductors disposed adjacent to each other within a preselected one of the slots may lead to an end of each of the phase coils. The fifth and sixth layer conductors disposed adjacent to each other within a preselected one of the slots may lead to the other end of each of the phase coils. The phase coils are connected to make a delta connection winding.

Each of the phase coils may have a bridging conductor segment extending over the anomaly conductor segment to establish a series connection of the first and second phase windings thereof. The bridging conductor segment includes the leg portions one of which is disposed within the slot in which the leg portion of one of the conductor segments leading to one of a pair of terminal leads of the each of the phase coils and forms a leading one of the leg portions of one of the first and second phase windings, and other of which is disposed within the slot in which the leg portion of one of the conductor segments leading to the other of the pair of terminal leads of the each of the phase coils and forms a trailing one of the leg portions of the one of the first and second phase windings. The tip portions of the leg portions of each of the bridging conductor segments are bent in the same circumferential direction of the armature winding.

The leg portions of the anomaly conductor segment of the first phase winding may be disposed, respectively, within two of the slots in which the leg portions of the anomaly conductor segment of the second phase winding are disposed A leg pitch of the leg portions of the anomaly conductor segment of the first phase winding is identical with that of the second phase winding.

A pair of terminal leads are provided which define ends of each of the phase coils which extends from an outside location in the slot within which the anomaly conductor segment is disposed.

Each of the slots may alternatively have 6n(=integer) of the leg portions of the conductor segments disposed.

The armature may further include a first terminal lead pair and a second terminal lead pair. The first terminal lead pair is made up of terminal leads forming ends of the first and second phase windings of each of the phase coils and leading to the first and second layer conductors disposed within one of the slots, respectively. The second terminal lead pair is made up of terminal leads forming the other ends of the first and second phase windings of each of the phase coils and leading to the fifth and sixth layer conductors disposed within one of the slots, respectively. m is an odd number greater or equal to three. The first terminal lead pairs of the phase coils is located at an interval away from each other which is equivalent to an electrical angle of 2π. The first terminal lead pairs of the phase coils form a first group, the second terminal lead pairs of the phase coils form a second group. A first angular range occupied by the first group overlap with a second angular range occupied by the second group. Each of the first and second angular ranges is an electrical angle of 2π(m−1)/m. Portions of the first terminal lead pair extending from the conductor segments are shifted from those of the second terminal lead pair by one slot pitch or more.

One of the terminal leads of the first terminal lead pair and one of the terminal leads of the second terminal lead pair may be connected at a neutral point. The other terminal lead of the first terminal lead pair and the other terminal lead of the second terminal lead pair may be connected to phase terminals, respectively. The phase coils are star-connected to make the armature winding.

The neutral point is located at an interval away from a junction of each of the first and second terminal lead pairs to the phase terminal by one slot pitch or more and defined intermediate between the junctions of the first and second terminal lead pairs in the circumferential direction of the armature core.

Ones of the terminal leads of the first and second terminal lead pairs which extend from the first layer conductors may be connected together to define a first neutral point. Ones of the terminal leads of the first and second terminal lead pairs which extend from the second layer conductors may be connected together to define a second neutral point. The first and second neutral points are separated from each other by given slot pitches in the circumferential direction of the armature core.

Ones of the terminal leads of the first terminal lead pairs and ones of the terminal leads of the second terminal lead pairs may be connected sequentially and lead to phase terminals. The first and second phase windings of each of the phase coils may be connected in parallel. The phase coils may be joined together to establish a delta-connection to make the armature winding.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawings, wherein like reference numbers refer to like parts in several views, particularly toFIG. 1, there is shown an ac machine1which may be used as an ac motor or an ac motor generator for automotive vehicles according to the invention.

The ac machine1is of a known structure which consists essentially of a rotor2, housings4aand4b, a rectifier5, an output terminal6, a rotary shaft7, brushes8, and slip rings9. The stator3is made up of a stator coil (i.e., an armature winding)31, and a stator core32. The stator core32is retained by the housings4aand4bin parallel to the rotary shaft7. The stator coil31is wound in slots350, as illustrated inFIG. 3, formed in the stator core32. The rotor2is of a rundel pole type and installed on the rotary shaft7supported rotatably by the housings4aand4bthrough bearings. The rotor2is disposed within the stator core32. The stator coil31is implemented by a three-phase armature winding made by passing conductor segment sets330, as clearly shown inFIG. 2, through the slots350, as shown inFIG. 3, formed in the stator core32through insulating sheets340from one side of the stator core32and joining adjacent two of the conductor segment sets330on the other side of the stator core32. This type of stator coil is well known in the art.

The stator coil31is, as described above, made up of the sequentially joined conductor segment sets330disposed partially within the slots350formed in the stator core32. Each of the conductor segment sets330will be described in detail below with reference toFIG. 2.

The conductor segment set330is made up of a large-size conductor segment331and a small-sized conductor segment332each of which consists of a substantially V-shaped head (will also be referred to as a V-shaped coil end), a pair of legs extending from the head into the slot350(will also be referred to as a slot-inserted portion below), and a pair of ends extending from the legs outside the stator core32(will also be referred to as a joint coil end below). Such a stator coil structure is well known in, for example, U.S. Pat. Nos. 6,201,332 B1, 6,249,956 B1, and 6,404,091 B1, all assigned to the same assignee as that of this application, disclosure of which is incorporated therein by reference. Each of the large-sized conductor segment331and the small-sized conductor segment332will also be referred generally to as a conductor segment33.

The heads or V-shaped coil ends of the conductor segment sets330are arrayed in the form of a ring on one side of the stator core32to form a first coil end312, as shown inFIG. 1. The joint coil ends are arrayed in the form of a ring on the other side of the stator core32to form a second coil end311.

Each of the conductor segment sets330is, as described above, made up of the large-sized conductor segment331and the small-sized conductor segment332. The large-sized conductor segment331, as can be seen inFIG. 2, surrounds or extends over the small-sized conductor segment332.

The large-sized conductor segment331consists of the head portion331c(i.e., the V-shaped coil end), the slot-inserted portions331aand331b, and the end portions331fand331g(i.e., the joint coil ends). The end portions331fand331gare welded at tips331dand331ewhich will also be referred to as welds below. The slot-inserted portion331awill also be referred to as a first layer conductor portion, and the slot-inserted portion331bwill also be referred to as a fourth layer conductor portion below.

The small-sized conductor segment332consists of the head portion332c, the slot-inserted portions332aand332b, and the end portions332fand332g. The end portions332fand332gare welded at tips332dand332ewhich will also be referred to as welds below. The slot-inserted portion332awill also be referred to as a second layer conductor portion, and the slot-inserted portion332bwill be referred to as a third layer conductor portion below.

InFIG. 2, each reference number with a dash (′) denotes the same portion as that referred to by a like reference number with no dash. In the illustrated example, the tips331dand332d′ located adjacent each other in the radius direction of the stator core32are welded together. Similarly, the tips332dand331d′ and the tips332eand331e′ are welded together.

In the example as illustrated inFIG. 2, the first layer conductor portion331aand the second layer conductor portion332aare placed within one of the slots350, while the fourth layer conductor portion331band the third layer conductor portion332bof the same conductor segment set33are placed within another slot350spaced at given magnetic pole pitches. The head portion332cof the small-sized conductor segment332is surrounded by the head portion331cof the large-size conductor segment331.

The stator core32has, as clearly shown inFIG. 3, the slots350having a length extending in the radius direction thereof. Within each of the slots35, the four slot-inserted portions331a,332a,332′, and331b′ are arrayed in line or aligned in the radius direction of the stator core32. In the following discussion, the four slot-inserted portions331a,332a,332b′, and331bplaced in each of the slots350will also be referred to as a first layer conductor portion to a fourth layer conductor portion, respectively, from inside to outside of the stator core32. The locations of the first to fourth layer conductor portions in each of the slots350will also be referred to below as a first layer position to a fourth layer position, respectively. In the illustrated example, the slot-inserted portions331b′ and332b′ belong to one of the conductor segment sets330which is different from the conductor segment sets330having the slot-inserted portions331aand332a.

The structure of the stator coil31made of three phase windings (will also be referred to as a U-phase coil, a V-phase coil, and a W-phase coil below) will be described below with reference toFIGS. 4 and 5.

FIGS. 4 and 5are developments each partially illustrating the stator coil31formed by a three-phase star-connected winding. The slot-inserted portion located at the first layer position within each of the slots350(i.e., the first layer conductor portion), the head portion, and the joint coil end of the conductor segment33are indicated by an alternate long and short dash line. The slot-inserted portion located at the second layer position within each of the slots350(i.e., the second layer conductor portion), the head portion, and the joint coil end extending therefrom are indicated by a broken line. The slot-inserted portion located at the third layer position within each of the slots350(i.e., the third layer conductor portion), the head portion, and the joint coil end extending therefrom are indicated by a solid line. The slot-inserted portion located at the fourth layer position within each of the slots350(i.e., the fourth layer conductor portion), the head portion, and the joint coil end extending therefrom are indicated by an alternate long and two short dashes line.

For the brevity of illustration, the stator coil31is designed to have four poles, but the poles may be increased further. The number of layers within each of the slots350may be more than four to increase an output of the ac machine1.

The U-phase, V-phase, and W-phase coils are identical in structure except for circumferential locations in the stator core32, and the following discussion will refer only to the U-phase coil for the brevity of disclosure.FIG. 6illustrates the U-phase coil made up of first and second phase windings10and11.FIG. 7illustrates the first phase winding10of the U-phase coil.FIG. 8illustrates the second phase winding of the U-phase coil. The first and second phase windings10and11are joined, as shown inFIG. 4, in parallel, and explanation thereof in detail will be omitted here.

The first and second phase windings10and11each include a wave winding segment34and lap winding segments35which are joined alternately.

The wave winding segments34are provided by the large-sized conductor segments331forming a wave winding coil and each include the first layer conductor portion, as indicated by the alternate long and short dash line, and the fourth layer conductor portion, as indicated by the alternate long and two short dashes line. Each of the wave winding segments34is formed by the large-sized conductor segment331with the joint coil ends projecting from the slots350in opposite circumferential directions. If a pole-to-pole pitch (will also be referred to as a pole pitch below) is identical with P slot-to-slot pitches (will also be referred to as a slot pitch below, P=6 in this embodiment), the welds of the joint coil ends of the large-sized conductor segment331is separated from each other at a pitch PW equal to (2P−1) slot pitches.

The lap winding segments35are provided by the small-sized conductor segments332forming a lap winding coil and each include the second layer conductor portion, as indicated by the broken line, and the third layer conductor portion, as indicated by the slid line. Each of the lap winding segments35is formed by the small-sized conductor segment332with the joint coil ends projecting from the slots350in approaching circumferential directions. The welds of the joint coil ends of the small-sized conductor segment332is separated from each other at a pitch PO equal to one slot pitch. Therefore, a total of the weld-to-weld pitches of each of the wave winding segments34and an adjacent one of the lap winding segments35will be two pole pitches (=2P slot pitches).

An interval between the slot-inserted portions of each of the wave winding segments34, that is, a leg-to-leg pitch (i.e., a back pitch) PWL of the large-size conductor segment331is identical with P−1 slot pitches (i.e., an interval between the five slots350). Similarly, an interval between the slot-inserted portions of each of the lap winding segments35, that is, a leg-to-leg pitch (i.e., a back pitch) POL of the small-size conductor segment332is identical with P−1 slot pitches. This permits the length of the joint coil ends to be decreased, thereby realizing a fractional-pitch winding.

The first phase winding10is, as can be seen inFIG. 7, made up of a first turn coil100which includes the lap winding segments35and the wave winding segment34joined between the lap winding segments35to form turns, a second turn coil101which is made up of the lap winding segments35and the wave winding segment34joined between the lap winding segments35to form turns and has the same winding direction as that of the first turn coil100, and a U-shaped anomaly conductor segment36aconnecting a trailing end of the first turn coil100and a leading end of the second turn coil101in series. The leg-to-leg pitch (i.e., a back pitch) of the anomaly conductor segment36ais shorter than those of the wave winding segments34and the lap winding segments35by one slot pitch (i.e., the interval between the slots350) or more.

The second phase winding11is, as can be seen inFIG. 8, equivalent electromagnetically to the first phase winding10and geometrically symmetrical with respect to the first phase winding10. The second phase winding11has a winding direction opposite to that of the first phase winding10. The second phase winding11has a U-shaped anomaly conductor segment36bidentical in structure with the anomaly conductor segment36aof the first phase winding10. The anomaly conductor segments36aand36bwill also be referred generally to as an anomaly conductor segment set36. The anomaly conductor segments36aand36bmay alternatively have the back pitch longer than those of the wave winding segments34and the lap winding segments35by one slot pitch or more.

The first phase winding10and the second phase winding11are joined in parallel to form the U-phase coil of the three-phase star-connected stator coil31. The U-phase coil has, as shown inFIG. 4, a pair of terminal leads33U which are joined to leading ones of the first layer conductor portions and the second layer conductor portions of the first and second phase windings10and11disposed within the same slot350, respectively. Similarly the V-phase coil and the W-phase coil have pairs of terminal leads33V and33W which are joined to leading ones of the first layer conductor portions and the second layer conductor portions of the first and second phase windings10and11disposed within the same slot350, respectively. The terminal leads33U,33V, and33W (i.e., interfaces between themselves and the joint coil ends of the conductor segments33) are separated from each other at four slot pitches.

The U-phase coil also has a pair of neutral point joint leads33U′ which are connected to trailing ones of the third layer conductor portions and the fourth layer conductor portions of the first and second phase windings10and11disposed within the same slot350, respectively. Similarly, the V-phase and W-phase coils also have pairs of neutral point joint leads33V′ and33W′ which are connected to trailing ones of the third layer conductor portions and the fourth layer conductor portions of the first and second phase windings10and11disposed within the same slot350, respectively. The neutral point joint leads33U′,33V′, and33W′ (i.e., interfaces between themselves and the joint coil ends of the conductor segments33) are separated from each other at four slot pitches. The neutral point joint leads33V′ and33W′, as clearly shown inFIG. 4, extend in a circumferential direction of the stator coil31without lapping over another and connect to the neutral point33N from which the terminal leads33U′ extend. This forms the three-phase star-connection armature winding (i.e., the stator coil31) with the three phase coils each made up of the first and second phase windings10and11joined in parallel.

The above arrangements of the terminal leads33U,33V,33W,33U′,33V′, and33W′ result in ease of drawing and shaping thereof, thereby simplifying production process of the stator coil31.

The terminal leads33U,33V, and33W may alternatively be connected to the third and forth layer conductor portions of the first and second phase windings10and11disposed within the same slot.350, respectively. The terminal leads33U′,33V′, and33W′ may alternatively be connected to the first and third layer conductor portions of the first and second phase windings10and11disposed in the same slot350, respectively.

The anomaly conductor segment36aof the first phase winding10and the anomaly conductor segment36bof the second phase winding11are, as described above, identical in back pitch with each other and disposed in the same slot350, therefore, they may be formed by preparing a large conductor segment like the large-sized conductor segment331and a small conductor segment like the small-sized conductor segment332as an anomaly conductor segment set and spreading (bending) and shaping the anomaly conductor segment set in a single process. This permits the anomaly conductor segments36aand26bto be inserted into the same slot350simultaneously, thus resulting in simplified manufacturing processes of the stator coil31.

The heads36cof the anomaly conductor segment sets36are, as clearly shown inFIG. 4, disposed within gaps between the terminal leads33U and33U′, between33V and33V′, and between33W and33W′ in the circumferential direction of the stator coil31, thus permitting the terminal leads33U,33V,33W,33U′,33V′, and33W′ to be collected within a desired range without physically interfering with the anomaly conductor segment sets36.

As apparent from the above discussion, the terminal leads33U,33V, and33W of the stator coil31extend from the m slots350which are located at an interval of 2π/m away from each other and lie within an angular range of 2π(m−1)/m where m is the number of phases and three (3) in this embodiment). Similarly, the neutral point joint leads33U′,33V′, and33W′ extend from the m slots350which are located at an interval of 2π/m away from each other and lie within an angular range of 2π(m−1)/m. This permits, as can be seen fromFIG. 4, the terminal leads33U,33V,33W,33U′,33V′, and33W′ extending outside the first coil end312to be arranged systematically in the circumferential direction of the stator coil31and collected within a desired range. A central one of the pairs of the neutral point joint leads33U′,33V′, and33W′, that is, the pair of terminal leads33U′, as described above, extends from the neutral point33N, thereby allowing the neutral point joint leads33V′ and33W′ to be identical in length and configuration with each other. This facilitates ease of production of the stator coil31.

The structure of the stator coil31also permits the length of portions of the terminal leads33U to33W′ extending in the circumferential direction to be decreased as compared with conventional structures, thus resulting in a decrease in electric resistance thereof.

The back pitches of the wave winding segments34and the lap winding segments35are shorter than the pole pitch P by one slot pitch, thus resulting in decreased interval between the coil ends, which results in decreases in winding resistance and leaking inductance. This serves to decrease the amount of heat dissipating from the generator7and improve an output of the generator7.

The structure in which the wave winding segment(s)34and the lap winding segments35are joined alternately permits the second coil end311to be made in a full-pitch winding fashion, thereby alleviating the problem, as underlying conventional automotive generator made of fractional pitch distributed windings, that one of the coil ends are undesirably long. This results in a decrease in electric resistance of the stator coil31.

FIG. 9shows the stator coil31according to the second embodiment of the invention which has the U-, V-, and W-phase coils delta-connected.

The arrangements of the slot-inserted portions of the conductor segment sets330and locations of the terminal leads33U,33V,33W,33U′,33V′, and33W′ are identical with those in the first embodiment. The terminal leads33U,33V, and33W are joined to the first and second layer conductor portions disposed within the same slots350, respectively. The terminal leads33U′,33V′, and33W′ are joined to the third and fourth layer conductor portions disposed within the same slots350, respectively.

The terminal leads33U,33V,33W,33U′,33V′, and33W′ are joined in the illustrated manner, thereby establishing the delta connection of the three-phase stator coil31made up of the first phase winding10and the second phase winding11joined in parallel to each other (seeFIG. 1).

The terminal leads33U,33V, and33W may alternatively be joined to the third and fourth layer conductor portions disposed within the same slots350, respectively. The terminal leads33U′,33V′, and33W′ may alternatively be joined to the first and second layer conductor portions disposed within the same slots350, respectively.

FIGS. 10 to 13show the ac machine1for use in automotive vehicles according to the third embodiment of the invention which has sixteen (16) poles. The stator coil31is identical in structure with that of the first embodiment except for increased slots350or conductor segment sets330. Additionally, the arrangements and connections of the terminal leads33U,33V,33W,33U′,33V′, and33W′ are identical with those in the first embodiment.

The ac machine1is equipped with a front frame110and a rear frame120and has the rotor2retained rotatably through bearings28and29. The front frame110and the rear frame120retain the stator core32. Through bolts41fasten and hold the stator core32from rotating.

A terminal table13is secured on a circumferential wall of the rear frame120through bolts43. The terminal table13has three-phase terminal bolts13awhich establish connections of input/output terminals of the ac machine1to three ac terminals of a three-phase inverter (not shown). The length of a first circumferential portion of the rear frame120extending in parallel to the rotary shaft21on which the terminal table13is not attached is shorter than that of a second circumferential portion, as indicated by a dashed line inFIG. 10, of the rear frame120to which the terminal table13is attached by a distance ΔL. Numeral42indicates an end surface of the second circumferential portion to which the terminal table13is attached. The decreased length of the first circumferential portion of the rear frame120results in a decreased length of the through bolts41. Specifically, the angular range occupied by the terminal leads33U,33V, and33W is, like the first embodiment, relatively small, thus permitting the length of the rear frame120extending parallel to the shaft21to be decreased.

The shaft21of the rotor2extends forwardly of the front frame110and has a pulley22installed on a front end thereof. The pulley110is mechanically connected to a drive pulley of the engine through a belt (not shown). The shaft21also has a rear end portion projecting from the rear frame120on which a brush unit14is installed. The brush unit14includes a pair of slip rings9installed on the rear end of the shaft21and a pair of brushes15placed in slidable contact with the slip rings9. The shaft21is press-fit within an axial hole of the rotor core24.

The rotor core24is made up of a front pole core24aand a rear pole core24band has a magnetic pole unit24cinstalled on an outer periphery thereof which is equipped with eight pairs of poles. The pole cores24aand24bretain a field coil25working to excite the rotor core24. The field coil25is connected at ends thereof to the slip rings9and supplied with power through the brush unit14.

The rotor core24has a front fan26and a rear fan27welded to ends thereof. The front and rear fans26and27work to rotate along with the rotor core24to suck fresh air for cooling purposes from air inlets16and17formed in the front and rear frames110and120. The front and rear frames110and120also have formed therein air outlets18and19from which the fresh air entering from the air inlets16and17is exhausted. Note that the air outlets19are omitted in the drawings for the brevity of illustration.

FIG. 11is a rear elevation of the ac machine1. The rear frame120has end surfaces450ranging over θ lying outside the area where the terminal table13is installed. The end surfaces450form recesses in the rear frame120, thus allowing the shorter through bolts41to be used.

FIG. 12is a longitudinal sectional view of the 16-pole stator3(i.e., the armature winding) consisting essentially of the stator core32and the stator coil31.FIG. 13is a rear elevation of the stator3. The stator core32includes a lamination of electromagnetic steel plates. The stator coil31includes a three-phase winding which is, like the first embodiment, wound through slots formed in the stator core32using insulating sheets.

An input/output line collection233made up of the terminal leads33U,33V, and33W extends from the first coil end312of the stator coil31backward. An electric connection of the stator coil31to an inverter (not shown) is, as clearly shown inFIGS. 12 and 13, accomplished by coupling crimp contacts3300secured to ends of the terminal leads33U,33V, and33W to metal connectors13bon the terminal table13.

The neutral points33N and the neutral point joint leads33U′,33V′, and33W′ extending circumferentially of the stator coil31to the neutral point33N are located radially inside the input/output line collection233and close to the rear of the first coil end312.

The second coil end311of the stator coil31is coated with epoxy resin for avoiding electric shorts between pairs of the welds of the conductor segment sets330.

FIG. 14is an enlarged development of the terminal leads33U,33V,33W,33U′,33V′, and33W′ and the first and second coil ends311and312.FIG. 15is a partial development which shows the first phase winding10.FIG. 16is a partial development which shows the second phase winding11. Specifically, the stator coil31of this embodiment is identical with the one in the first embodiment except that the neutral point joint leads33U′,33V′, and33W′ are broken down into two circuits, and the slots350are increased.

The terminal leads33U,33V, and33W, one pair for each phase of the stator coil31, are, like the first embodiment, extend from the third and fourth layer conductor portions disposed within the same slots350, respectively. The neutral point joint leads33U′,33V′, and33W′, one pair for each phase of the stator coil31, extend from the first and second layer conductor portions disposed within the same slots350, respectively, and lead to the neutral points33N to form a three-phase star-connected winding. This results in, like the first embodiment, simplified arrangements and connections of the terminal leads33U,33V,33W,33U′,33V′, and33W′.

Use of the two neutral points33N permits the number of joints to each of the neutral points33N to be decreased to three, thus resulting in ease of welding the terminal leads33U′,33V′, and33W′ to the neutral points33N.

The anomaly conductor segments36aand36bof the anomaly conductor segment set36connecting the first turn coil100and the second turn coil101, as shown inFIG. 15, are identical in back pitch thereof, and the slot-inserted portions thereof are disposed within the same slots350, respectively, thereby resulting in, like the first embodiment, a decreased time for production processes of the stator coil31.

FIGS. 17 to 19show a comparative example of a stator coil made of a three-phase star-connection winding consisting of pairs of phase windings connected in parallel, one pair for each phase. Comparison betweenFIGS. 17 to 19andFIGS. 12 to 14shows that use of the fractional pitch winding as the stator coil31in the first and third embodiments results in a decreased total size and simplified arrangements of the terminal leads33U,33V,33W,33U′,33V′, and33W′ as compared with a full-pitch winding, as illustrated inFIGS. 17 to 19.

FIG. 20is a development which shows a stator coil, as taught in U.S. Pat. No. 6,417,592 B2 (corresponding to Japanese Patent First Publication No. 2001-169490), assigned to the same assignee as that of this application. As compared with the shown structure, it is found that the terminal leads33U,33V,33W,33U′,33V′, and33W′ in the above embodiments are greatly reduced in size and simplified in arrangement.

The three conductor segment sets330may alternatively be arrayed in the radius direction within each of the slots350of the stator core32to make a three times turn stator coil. In this case, the conductor segment sets330located at innermost layer positions in the slots350are joined, like the first and second phase windings10and11connected in parallel in the first embodiment, to form a phase winding X. The conductor segment sets330located at outermost layer positions in the slots350are joined, like the first and second phase windings10and11connected in parallel in the first embodiment, to form a phase winding Y. The conductor segment sets330located at middle layer positions in the slots350are joined, like the first and second phase windings10and11connected in parallel in the third embodiment, to form a phase winding Z. The phase windings X, Y, and Z are joined in series to complete the three times turn stator coil.

FIGS. 21 to 24show the stator coil31according to the fourth embodiment of the invention.FIG. 21is a development showing a U-phase coil.FIG. 22is a development showing the first phase winding10of the U-phase coil ofFIG. 21.FIG. 23is a development showing the second phase winding of the U-phase coil ofFIG. 21.FIG. 24is a development showing a bridging conductor segment37. The V-phase and W-phase coils are, as already described, identical in structure with the U-phase coil, and explanation thereof in detail will be omitted here.

The stator coil31of this embodiment is different from that of the first embodiment only in that the U-phase coil is made up of the first and second phase windings10and11connected in series.

The slot-inserted portion disposed at the first layer position within each of the slots350of the stator core32, the V-shaped head portion, and the joint coil end of the conductor segments33are, like the first embodiment, indicated by an alternate long and short dash line. The slot-inserted portion disposed at the second layer position within each of the slots350, the head portion, and the joint coil end extending therefrom are indicated by a dashed line. The slot-inserted portion disposed at the third layer position within each of the slots350, the head portion, and the joint coil end extending therefrom are indicated by a solid line. The slot-inserted portion disposed at the fourth layer position within each of the slots350, the head portion, and the joint coil end extending therefrom are indicated by an alternate long and two short dashes line.

The stator coil31is of a four-pole structure, but the number of poles may be more than four. The conductor segment sets330disposed within each of the slots350may be increased for increasing an output voltage.

The anomaly conductor segment sets36are, like the first embodiment, each made up of the anomaly conductor segment36aof the first phase winding10, as illustrated inFIG. 22, and the anomaly conductor segment36bof the second phase winding11, as illustrated inFIG. 23.

A series-connection of the first and second phase windings10and11is accomplished by joining the terminal lead33U′ leading to a trailing one of the slot-inserted portions (i.e., the fourth layer conductor portion) of the first phase winding10and the terminal lead33U′ leading to a leading one of the slot-inserted portions (i.e., the second layer conductor portion) of the second phase winding11. Note that the trailing slot-inserted portion, as referred to herein, is one of the slot-inserted portions of the first phase winding10or the second phase winding11that is the farthest from the terminal lead33U,33V, or33W, and the leading slot-inserted portion is one of the slot-inserted portions of the first phase winding10or the second phase winding11that is the closest to the terminal lead33U,33V, or33W.

Specifically, the series-connection of the first and second phase windings10and11is accomplished by disposing two slot-inserted portions2000and2001of the U-shaped bridging conductor segment37, as clearly shown inFIG. 24, in the fourth layer position within the No. 2 slot and the second layer position within the No. 20 slot, respectively. The first phase winding10extends in a circumferential clockwise direction of the stator coil31, while the second phase winding11extends in a circumferential counterclockwise direction of the stator coil31, therefore, a joint coil end3001of the bridging conductor segment37, unlike the wave winding segments34, is bent to the circumferential counterclockwise direction.

The structure of the bridging conductor segment37will be described in more detail with reference toFIG. 24.

The bridging conductor segment37consists of legs or the slot-inserted portions2000and2001, the first joint coil end3000leading to the slot-inserted portion2000, the tip5000, the slant head portions4000and4001continuing from the tip5000, and the second joint coil end3001leading to the slot-inserted portion2001. The slot-inserted portion2000, the first joint coil end3000, and the slant head portion4000extend from the fourth layer position within the slot350. The slot-inserted portion2001, the second joint coil end3001, and the slant head portion4001extend from the second layer position within the slot350.

Usually, the joint coil ends (i.e., the end portions331f,331g,332f, and332g, as illustrated inFIG. 2) of the conductor segments33are spread or bent in production processes of the stator coil31by rotating adjacent two of four rings with slots into which the conductor segments33are inserted in opposite circumferential directions. In the fourth embodiment, the joint coil ends leading to the slot-inserted portions disposed in the second and fourth layer positions within the slot350are bent in the circumferential counterclockwise direction of the stator coil31, thus permitting the first and second joint coil ends3000and3001to be bent in the same direction simultaneously. This bending process may be implemented in any of several manners as known in the art. The bridging conductor segment37may alternatively formed by bending end portions of I-shaped conductors and then welding two of the end portions.

In the manner as described above, the first and second phase windings10and11are joined in series to form the stator coil31, thus permitting a two times higher voltage to be applied to or outputted from the ac machine1.

The three conductor segment sets330may alternatively be arrayed in the radius direction within each of the slots350of the stator core32to make a three times turn stator coil. In this case, the conductor segment sets330located at innermost layer positions in the slots350are joined, like the first and second phase windings10and11connected in parallel in the first embodiment, to form a phase winding X. The conductor segment sets330located at outermost layer positions in the slots350are joined, like the first and second phase windings10and11connected in parallel in the first embodiment, to form a phase winding Y. The conductor segment sets330located at middle layer positions in the slots350are joined, like the first and second phase windings10and11connected in parallel in the third embodiment, to form a phase winding Z. The phase windings X, Y, and Z are joined in series to complete the three times turn stator coil. Alternatively, a total of the six phase windings10and11may be joined in series in the manner as described in the third embodiment to form a six times turn stator coil.

FIG. 25shows the ac machine1for use in automotive vehicles according to the fifth embodiment of the invention.

The ac machine1consists essentially of the stator3, the rotor2, the housing50, the rotary shaft7, the rectifier5, the brushes8, and the slip rings9.

The stator3is retained by an inner peripheral wall of the housing50. Specifically, the housing50is made up of two separate parts. The retention of the stator3is achieved by joining the separate parts together, as clearly shown in the drawing. The rotary shaft7has installed thereon the rotor2and is rotatably supported by end walls of the housing50using a pair of bearings. The rotary shaft7is mechanically connected to the engine through a pulley (not shown).

The rotor2is made up of a rundel pole type pole core80with claw-like magnetic poles and the field coil110installed on the pole core80. The field coil110is supplied with power from the brushes8through the slip rings9.

The stator3is made up of the stator core32and the stator coil31implemented by a three-phase star-connected winding. The stator core32, as clearly shown inFIG. 26, has formed thereon teeth T which define equi-angular spaced slots350. The stator coil31is made up of sequentially joined U-shaped conductor segments33inserted into the slots350. The insulators340work to insulate the conductor segments33from the stator core32. Each of the conductor segments33consists of a pair of legs or slot-inserted portions633, the V-shaped coil end611extending from the slot-inserted portions633outside an end of the stator core32, a pair of joint coil ends612extending from the slot-inserted portions33outside the other end of the stator core32.

The stator core32has formed therein the slots350, two (q=2) for each pole in each phase. A total of p·q·m(p=the number of poles, m=the number of phases) slots350are arrayed at regular intervals in the circumferential direction of the stator core32.

The stator coil31is made up of the conductor segments33which are partially inserted into the slots350from the right to left, as viewed inFIG. 27. Each end of the conductor segments33is welded, as denoted at34, to one of the ends of another conductor segment33to form three phase coils (i.e., the U-phase, V-phase, and W-phase coils) which are coupled together to form the so-called three-phase star-connected winding. The U-phase, V-phase, and W-phase coils may alternatively be joined together through the so-called delta connection.

Within each of the slots350, six of the slot-inserted portions633are arrayed in line or aligned in the radius direction of the stator core32. In the following discussion, the six slot-inserted portions633disposed within each of the slots350will also be referred to as a first, a second, a third, a fourth, a fifth, and a sixth layer conductor portion, respectively, from inside to outside of the stator core32. Specifically, the innermost one of the slot-inserted portions633disposed in each of the slots350forms the first layer conductor portion, the second innermost one forms the second layer conductor portion, the third innermost one forms the third layer conductor portion, the outermost one forms the sixth layer conductor portion, the second outermost one forms the fifth layer conductor portion, and the third outermost one forms the fourth layer conductor portion. The locations of the first to sixth layers in each of the slots350will also be referred to as first, second, third, fourth, fifth, and sixth layer positions below. The first to sixth layer conductor portions will also be designated below at reference numerals731,732,733,734,735, and736, respectively. The two slot-inserted portions633of each of the conductor segments33are inserted into two of the slots350spaced from one another at a given interval (e.g., an electrical angle π), and placed in different layer positions in the slots350.

Numeral300inFIG. 27indicates a wave winding segment (i.e., the large-sized conductor segment331) with the slot-inserted portions633placed at the first and sixth layer positions. Numeral301indicates a lap winding segment (i.e., the small-sized conductor segment332) with the slot-inserted portions633placed at the second and third layer positions. Numeral302indicates a lap winding segment (i.e., the small-sized conductor segment332) with the slot-inserted portions633placed at the fourth and fifth layer positions. The wave winding segment300extends over the lap winding segments301and302.

The term “wave winding segment”, as used herein, represents the conductor segment33having the joint coil ends612extending in opposite circumferential directions of the stator core32. The term “lap winding segment” represents the conductor segment33having the joint coil ends612extending in approaching circumferential direction of the stator core32.

The stator coil31is, as described above, made up of the U-phase, V-phase, and W-phase coils which are star-connected. The U-phase, V-phase, and W-phase coils are identical in structure with each other, and reference will be made only to the U-phase coil below.

FIG. 28shows a circuit diagram of the U-phase coil3U.

The U-phase coil3U is made up of the first phase winding10and the second phase winding11which are joined in parallel. The first phase winding10consists of the first turn coil3000, the second turn coil4000, and the anomaly conductor segment5000connecting them in series. Similarly, the second phase winding11consists of the first turn coil3001, the second turn coil4001, and the anomaly conductor segment5001connecting them in series. The first turn coil3001and the second turn coil4001may be interchanged with one another. The first turn coil3000and the second turn coil4000may also be interchanged with one another.

FIG. 29is a development illustrating the U-phase coil3U.FIG. 30is a development illustrating the first phase winding10. FIG.31is a development illustrating the second phase winding11.

An alternate long and short dash line represents one of the slot-inserted portions633of the conductor segment33disposed at the first layer position within each of the slots350, the V-shaped coil end311, and the joint coil end312extending therefrom. A dashed line on the right side of the alternate long and short dash line represents one of the slot-inserted portions633of the conductor segment33disposed at the second layer position within each of the slots350, the V-shaped coil end311, and the joint coil end312extending therefrom. A solid line on the left side of the dashed line represents one of the slot-inserted portions633of the conductor segment33disposed at the third layer position within each of the slots350, the V-shaped coil end311, and the joint coil end312extending therefrom. An alternate long and two short dashes line on the left side of the solid line represents one of the slot-inserted portions633of the conductor segment33disposed at the fourth layer position within each of the slots350, the V-shaped coil end311, and the joint coil end312extending therefrom. A dashed line on the left side of the alternate long and two dashes line represents one of the slot-inserted portions633of the conductor segment33disposed at the fifth layer position within each of the slots350, the V-shaped coil end311, and the joint coil end312extending therefrom. A solid line on the leftmost side within each of the slots350represents one of the slot-inserted portions633of the conductor segment33disposed at the sixth layer position within each of the slots350, the V-shaped coil end311, and the joint coil end312extending therefrom. For the brevity of illustration,FIGS. 29 to 31omit halves of the conductor segments33and show a four-pole structure. The number of poles may be another value.

The first phase winding10is, as described above, made up of the first turn coil3000, the second turn coil4000, and the anomaly conductor segment5000connecting them in series.

The first turn coil3000is formed by joining, in sequence, the wave winding segments300with the first and sixth layer conductor portions731and736, the first lap winding segments301with the second and third layer conductor portions732and733, and the second lap winding segments302with the fourth and fifth layer conductor portions734and735. Specifically, the slot-inserted portions633of the conductor segments33are joined, in sequence, from the first layer conductor portion731, to the second layer conductor portion732, to the third layer conductor portion733, to the fourth layer conductor portion734, to the fifth layer conductor portion735, to the sixth layer conductor portion736, and to the first layer conductor portion731.

If the pole pitch is set to P slot pitches (P=6 in this embodiment), that is, the two slots350are provided for each pole in each phase, a weld-to-weld pitch PW of the joint coil ends612of the wave winding segments300is identical with (2P−1) slot pitches. A weld-to-weld pitch P1of the first lap winding segments301is identical with half the slot pitch (½). Similarly, a weld-to-weld pitch P2of the second lap winding segments302is identical with half the slot pitch (½). A weld-to-weld pitch of a combination of the wave winding segment300and the first and second lap winding segments301and302is, therefore, identical with two pole pitch (2P). An interval between the slot-inserted portions633of each of the wave winding segments300and the first and second lap winding segments301and302, that is, a leg-to-leg pitch is identical with P−1 slot pitches. Specifically, the V-shaped coil ends611and the joint coil ends612are arrayed at fractional pitches, thus permitting lengths thereof in the circumferential direction of the stator coil31to be decreased.

The first turn coil3000of the first phase winding10extends from the U-phase terminal lead33U, to half of the wave winding segment300(i.e., the first layer conductor portion731), to the first lap winding segment301(i.e., the second and third layer conductor portions732and733), to the second lap winding segment302(i.e., the fourth and fifth layer conductor portions734and735), to the wave winding segment300(i.e., the sixth and first layer conductor portions736and731), to the first lap winding segment301(i.e., the second and third layer conductor portions732and733), and to the second lap winding segment302(i.e., the fourth and firth layer conductor portions734and735) and leads to the second turn coil4000through the anomaly conductor segment5000(i.e., the sixth and first layer conductor portions736and731).

The anomaly conductor segment5000with the slot-inserted portions disposed in the sixth and first layer position of the slots350has the leg-to-leg pitch (i.e., back pitch) shorter than that of the wave winding segments300by at least one slot pitch. One of the slot-inserted portions633of the anomaly conductor segment5000forms a trailing one of the slot-inserted portions633of the first turn coil3000, while the other slot-inserted portion633forms a leading one of the slot-inserted portions633of the second turn coil4000.

The second turn coil4000is different from the first turn coil3000in that it is shifted to the left by one slot pitch. The configuration and winding direction are identical. The slot-inserted portion633of the anomaly conductor segment5000forming a leading one of the slot-inserted portions633of the second turn coil4000is, however, disposed in the first layer position. Following this, the second turn coil4000extends to the second and third layer conductor portions732and733of the first lap winding segment301and to the fourth and fifth layer conductor portions734and735of the second lap winding segment302and leads to the neutral point33N through the sixth layer conductor portion736of the wave winding segment300.

The second phase winding11is, as described above, made up of the first turn coil3001, the second turn coil4001, and the anomaly conductor segment5001connecting them in series.

The first turn coil3001is, as shown inFIG. 31, formed by joining, in sequence, the wave winding segments300with the first and sixth layer conductor portions731and736, the first lap winding segments301with the second and third layer conductor portions732and733, and the second lap winding segments302with the fourth and fifth layer conductor portions734and735. Specifically, the slot-inserted portions633of the conductor segments33are joined, in sequence, from the second layer conductor portion732, to the first layer conductor portion731, to the sixth layer conductor portion736, to the fifth layer conductor portion735, to the fourth layer conductor portion734, to the third layer conductor portion733, and to the second layer conductor portion732.

If the pole pitch is set to P slot pitches (P=6 in this embodiment), that is, the two slots350are provided for each pole in each phase, the weld-to-weld pitch PW of the joint coil ends612of the wave winding segments300is identical with (2P−1) slot pitches. The weld-to-weld pitch P1of the first lap winding segments301is identical with half the slot pitch (½). Similarly, the weld-to-weld pitch P2of the second lap winding segments302is identical with half the slot pitch (½). The weld-to-weld pitch of a combination of the wave winding segment300and the first and second lap winding segments301and302is, therefore, identical with two pole pitch (2P). An interval between the slot-inserted portions633of each of the wave winding segments300and the first and second lap winding segments301and302, that is, a leg-to-leg pitch is identical with P−1 slot pitches. Specifically, the V-shaped coil ends611and the joint coil ends612are arrayed at fractional pitches, thus permitting lengths thereof in the circumferential direction of the stator coil31to be decreased.

The first turn coil3001of the second phase winding11extends from the U-phase terminal lead33U, to half of the first lap winding segment301(i.e., the second layer conductor portion732), to the wave winding segment300(i.e., the first and sixth layer conductor portions731and736), to the second lap winding segment302(i.e., the fifth and fourth layer conductor portions735and734), to the first lap winding segment301(i.e., the third and second layer conductor portions733and732), to the second lap winding segment302(i.e., the third and second layer conductor portions733and732), and to the wave winding segment300(i.e., the first and sixth layer conductor portions731and736) and leads to the second turn coil4001through the anomaly conductor segment5001(i.e., the third and fourth layer conductor portions733and734).

The anomaly conductor segment5001with the slot-inserted portions disposed in the third and fourth layer position of the slots350has the leg-to-leg pitch (i.e., back pitch) shorter than that of the first and second lap winding segments301and302by at least one slot pitch. One of the slot-inserted portions633of the anomaly conductor segment5001forms a trailing one of the slot-inserted portions633of the first turn coil3001, while the other slot-inserted portion633forms a leading one of the slot-inserted portions633of the second turn coil4001.

The second turn coil4001is different from the first turn coil3001in that it is shifted to the left by one slot pitch. The configuration and winding direction are identical. The slot-inserted portion633of the anomaly conductor segment5001forming a leading one of the slot-inserted portions633of the second turn coil4001is, however, disposed in the fourth layer position. Following this, the second turn coil4001extends to the third and second layer conductor portions733and732of the first lap winding segment301and to the first and sixth layer conductor portions731and736of the wave winding segment300and leads to the neutral point33N through the fifth layer conductor portion735of the second lap winding segment302.

FIG. 32shows locations of the slot-inserted portions633of the first and second phase windings10and11within the slots350.

The slot-inserted portions633of the U-phase coil3U are disposed within the slots350of numbers #2, #20, and #14. Some of the layer positions of the left slots350of numbers #21 and #15 are illustrated as being empty, however, the slot-inserted portions633of the W-phase coil are, in practice, disposed therein. Similarly, the slot-inserted portions633of the W-phase coil are disposed in some of the layer positions of the slots350illustrated as being empty.

The anomaly conductor segments5000and5001may alternatively have the back pitch longer than those of the wave winding segments300and the first and second lap winding segments301and302by one slot pitch.

FIG. 33is a development illustrating the stator coil31formed by a star-connection of the U-phase coil3U, the V-phase coil, and the W-phase coil.

The U-phase coil, the V-phase coil, and the W-phase coils have pairs of terminal leads33U,33V, and33W, respectively. The terminal leads33U lead to adjacent two of the slot-inserted portions633disposed within one of the slots350. The same is true for the terminal leads33V and33W.

The U-phase, the V-phase, and the W-phase coils are connected at the neutral point33N through neutral joint leads33N′.36C denotes either of the anomaly conductor segments5000and5001. The neutral terminal leads33N′ are provided, one pair for each phase. The neutral terminal leads33N′ of each pair lead to adjacent two of the slot-inserted portions633disposed within one of the slots350.

Specifically, as shown inFIG. 33, the terminal leads33U connecting with ends of the first and second phase windings10and11of the U-phase coil extend from adjacent two of the slot-inserted portions633(i.e., the first and second layer conductor portions731and732) disposed within one of the slots350. The same is true for the terminal leads33V and33W of the V-phase and W-phase coils. The neutral point joint leads33N′ connecting with other ends of the first and second phase windings10and11of the U-phase coil extend from adjacent two of the slot-inserted portions633(i.e., the sixth and fifth layer conductor portions736and735) disposed within one of the slots350. The same is true for the V-phase and W-phase coil. This facilitates ease of arrangement of the terminal leads33U to33W and33N′ and connection of the terminal leads33N′ at the neutral point33N and the terminal leads33U to33W with external terminals and also ease of shaping and production of the terminal leads33U to33W and33N′. Alternatively, the terminal leads33U may extend from the sixth and fifth layer conductor portions736and735, while the neutral point joint leads33N′ may extend from the first and second layer conductor portions731and732.

The intervals or back pitches between the slot-inserted portions633of the anomaly conductor segments5000and5001are identical with each other, thus permitting the anomaly conductor segments5000and5001to be manufactured simultaneously by inserting a large-sized conductor and a small-sized conductor into slots of rings and rotating the rings in opposite directions to spread or bend end portions of the large-sized and small-sized conductor segments to form the U-shaped anomaly conductor segments5000and5001, respectively.

The neutral point joint leads33N′ extend from the slot-inserted portions633(i.e., trailing ones of the slot-inserted portions633of the second turn coils4000and4001) disposed outside the slot-inserted portions633of the anomaly conductor segments5000and5001. The terminal leads33U (33V or33W) extend from the slot-inserted portions633(i.e., leading ones of the slot-inserted portions633of the first turn coils3000and3001). This permits the heads of the anomaly conductor segments5000and5001, the neutral point joint leads33N′ and the terminal leads33U,33V, and33W to be arranged without any physical interference with each other. This also improves freedom in arranging the leads33N′,33U,33V, and33W.

As apparent from the above discussion, the stator coil31is made up of the first and second phase windings10and11that are electromagnetically equivalent to each other, thus allowing the first and second phase windings10and11to be changed from a series connection to a parallel connection or vice versa easily, which facilitates use of the ac machine1with different voltage batteries.

Two of the slots350are provided for each pole in each phase. The six slot-inserted portions633are disposed within each of the slots350. This results in an increase in turn of the stator coil31without an increase in poles, which enables use of the ac machine1on higher voltages. The interval or pitch between the slot-inserted portions633of each of the wave winding segments300and the first and second lap winding segments301and302is shorter than the pole pitch by one slot pitch, thus allowing a projected length of one of the coil ends of the stator coil31to be decreased. This eliminates the problem involved in conventional stator coil structures that the length of one of the coil ends projecting from the end surface of the stator core32is undesirabley longer than that of the other coil end and results in a decrease in electric resistance of the stator coil31, which improves an output of the ac machine1without increasing magnetic noises.

FIG. 34shows a modification of the stator coil31of the fifth embodiment in which the U-phase, V-phase, and W-phase coils are delta-connected.

The neutral point joint leads33U′,33V′, and33W′, like the ones ofFIG. 9, are provided which lead to trailing ones of the slot-inserted portions633of the second phase coils4000and4001of the respective U-phase, V-phase, and W-phase coils and coupled with each other through a delta connection.

FIG. 35shows the U-phase coil3U of the stator coil31according to the sixth embodiment of the invention.FIG. 36is a development illustrating the U-phase coil3U.FIG. 37shows the first phase winding10of the U-phase coil3U.FIG. 38shows the second phase winding11of the U-phase coil3U.

The U-phase coil3U is, as clearly shown inFIG. 35, made up of the first phase winding10and the second phase winding11, as described in the fifth embodiment, which are joined in series through a bridging conductor segment6000.

The bridging conductor segment6000has the two slot-inserted portions633, like the ones shown inFIGS. 26 and 27, one is a trailing one of the slot-inserted portions633of the second turn coil4000of the first phase winding10which corresponds to a trailing one of the slot-inserted portions633of the second turn coil4000of the first phase winding10leading to the neutral point joint lead33N′ in the fifth embodiment, and another is a leading one of the slot-inserted portions633of the first turn coil3001of the second phase winding11which corresponds to a leading one of the slot-inserted portions633of the first turn coil3001of the second phase winding11leading to the terminal lead33U in the fifth embodiment.

The bridging conductor segment6000, thus, turns a winding direction of the second turn coil4000of the first phase winding10to that of the first turn coil3001of the second phase winding11. Specifically, the structure of the stator coil31of this embodiment is capable of use of the ac machine1on different voltages by changing a joint of the first and second phase windings10and11between the series connection and the parallel connection and/or a joint of the U-phase, V-phase, and W-phase coils between the star connection and the delta connection.

FIGS. 39 to 42show the ac machine1according to the seventh embodiment of the invention.

The ac machine1is of a sixteen (16) pole structure and identical in structure of the stator coil31with those of the above fifth and sixth embodiments. Within each of the slots350of the stator core32, six of the slot-inserted portions633are arrayed in line or aligned in the radius direction of the stator core32. Unlike the above embodiments, the slot-inserted portions633disposed in each of the slots350will be referred to as first, second, third, fourth, fifth, and sixth layer conductor portions in the order of radially outward locations. Specifically, the first, second, third, fourth, fifth, and sixth layer conductor portions are arrayed radially from outside to inside the stator core31. The pair of neutral point joint leads33N′ extend from the fifth and sixth layer conductor portions. The terminal leads33U,33V, and33W extends from first and second layer conductor portions. The stator coil31is identical in structure with that of the fifth embodiment. Specifically, the first and second phase windings10and11of each of the U-phase, V-phase, and W-phase coils are connected in parallel. The U-phase, V-phase, and W-phase coils are star-connected.

InFIG. 41, numeral3110denotes a coil end of the stator coil31made up of the V-shaped coil ends611of the conductor segments33. Numeral3120denotes a coil end of the stator coil31made up of the joint coil ends612of the conductor segments33.

Referring back toFIG. 39, the ac machine1has a front frame110and a rear frame120which supports therein the rotor2rotatably using a pair of bearings. The front frame110and the rear frame120retain the stator core32therebetween and are joined firmly by through bolts410to hold the stator core32from rotating.

The terminal table13is secured on a circumferential wall of the rear frame120through bolts43. The terminal table13has three-phase terminal bolts13awhich work to establish connections of input/output terminals of the ac machine1to three ac terminals of a three-phase inverter (not shown). The length of a first circumferential portion, as denoted by θ inFIG. 40, of the rear frame120extending parallel to the rotary shaft21on which the terminal table13is not attached is shorter than that of a second circumferential portion, as indicated by a dashed line inFIG. 39, of the rear frame120to which the terminal table13is attached by the distance ΔL. Numeral42indicates an end surface of the second circumferential portion to which the terminal table13is attached. The decreased length of the first circumferential portion, as denoted by θ inFIG. 40, of the rear frame120results in a decreased length of the through bolts41. Specifically, the angular range occupied by the terminal leads33U,33V, and33W is, like the first embodiment, relatively small, thus permitting the length of the rear frame120extending parallel to the shaft21to be decreased.

Specifically, within an angular range equivalent to approximately two pole pitches within which the terminal leads33U,33V, and33W and the neutral point joint leads33N′ are arranged, ends of the leads33U to33W and33N′ project in the axial direction of the ac machine1, thereby permitting the terminal table13to be mounted within that angular range. This permits the length of the first circumferential portion of the rear frame120ranging over θ on which the terminal table13is not installed to be decreased, thus resulting in a decreased weight of the rear frame120and improving mountability of the ac machine1.

FIG. 41is a cross sectional view, as taken along the line A—A inFIG. 42, which shows the 16-pole stator3(i.e., armature) consisting essentially of the stator core32and the stator coil31.FIG. 42is a rear elevation of the stator3. The stator core32includes a lamination of electromagnetic steel plates. The stator coil31includes a three-phase winding which is, like the fifth embodiment, wound through slots formed in the stator core32using insulating sheets. The input/output line correction233made up of the terminal leads33U,33V, and33W extends from the first coil end312of the stator coil31backward. An electric connection of the stator coil31to an inverter (not shown) is accomplished by coupling crimp contacts3300secured on ends of the terminal leads33U,33V, and33W to metal connectors13bon the terminal table13, as shown inFIG. 39.

One of the two neural points33N is provided at a location coinciding with the fifth layer position of one of the slot350of the stator core32, while the other neutral point33N is provided at a location coinciding with the sixth layer position of one of the slot350of the stator core32.

Ends of the first phase windings10of the respective U-phase coil, V-phase coil, and W-phase coil extend from the fifth layer conductor portions in the slots350and are bent in the circumferential direction of the stator coil31as the neutral point joint leads33N′ which are, in turn, welded at one of the neutral point33N provided between the terminal lead33U of the U-phase coil and the terminal lead33V of the V-phase coil. Ends of the second phase windings11of the respective U-phase coil, V-phase coil, and W-phase coil extend from the sixth layer conductor portions in the slots350and are bent in the circumferential direction of the stator coil31as the neutral point joint leads33N′ which are, in turn, joined at the other neutral point33N provided between the terminal lead33W of the W-phase coil and the terminal lead33V of the V-phase coil. The second coil end3120of the stator coil31is coated with epoxy resin for avoiding electric shorts between pairs of the welds of the conductor segment sets330. Use of the two neutral points33N permits the number of joints to each of the neutral points33N to be decreased to three, thus resulting in ease of welding the terminal leads33U′,33V′, and33W′ to the neutral points33N.

Each of the slots350of the stator core32may alternatively be designed to have 6×n (n=integer) layer positions to dispose the n conductor segment sets330therein to make n sets of phase windings. The phase windings are joined in series or parallel to increase turns of the stator coil31.

FIGS. 43 to 46show stator coil31according to the eighth embodiment of the invention which is different from those in the first to third embodiments in that it is made of a full-pitch winding. Specifically, the stator coil31has the four slot-inserted portions of the conductor segment sets330disposed in each of the slots350of the stator core32. Parts of the ac machine1of this embodiment other than the stator coil31and leads thereof are identical with those of the first to third embodiment, and explanation thereof in detail will be omitted here.

The stator coil31has the U-phase, V-phase, and W-phase coils star-connected, but they may alternatively be delta-connected. The U-phase, V-phase, and W-phase coils may alternatively be connected at a single neutral point.

InFIGS. 43 and 44, an alternate long and short dash line, likeFIGS. 4 and 5, represents one of the slot-inserted portions of the conductor segment33disposed at the first layer position within each of the slots350of the stator core32, the V-shaped coil end311, and the joint coil end312extending therefrom. A dashed line represents one of the slot-inserted portions of the conductor segment33disposed at the second layer position within each of the slots350, the V-shaped coil end311, and the joint coil end312extending therefrom. A solid line represents one of the slot-inserted portions of the conductor segment33disposed at the third layer position within each of the slots350, the V-shaped coil end311, and the joint coil end312extending thereform. An alternate long and two short dashes line represents one of the slot-inserted portions of the conductor segment33disposed at the fourth layer position within each of the slots350, the V-shaped coil end311, and the joint coil end312extending therefrom. For the brevity of illustration,FIGS. 43 and 44omit halves of the conductor segments33.

Like the first embodiment, each of the U-phase coil, the V-phase coil, and the W-phase coil is made up of the first phase winding10and the second phase winding11. The first and second phase windings10and11are connected in parallel, but may alternatively be connected in series. Each of the first and second phase windings10and11is, like the first embodiment, made up of the wave winding segments34and the lap winding segments35joined alternately.

The first phase winding10of the U-phase coil starts from the first layer conductor portion disposed within the #9 slot (not shown inFIG. 43) leading to the terminal601through the terminal lead501and extends circumferentially from the fourth layer conductor portion disposed in the #16 slot to the first neutral point N1through the terminal lead502.

The second phase winding11of the U-phase coil starts from the second layer conductor portion disposed within the #9 slot (not shown inFIG. 43) leading to the terminal602through the terminal lead503and extends circumferentially from the third layer conductor portion disposed in the #16 slot to the second neutral point N2through the terminal lead504.

The first phase winding10of the V-phase coil starts from the first layer conductor portion disposed within the #29 slot leading to the terminal603through the terminal lead505and extends circumferentially from the fourth layer conductor portion disposed in the #36 slot to the first neutral point N1through the terminal lead506.

The second phase winding11of the V-phase coil starts from the second layer conductor portion disposed within the #29 slot leading to the terminal604through the terminal lead507and extends circumferentially from the third layer conductor portion disposed in the #36 slot to the second neutral point N2through the terminal lead508.

The first phase winding10of the W-phase coil starts from the first layer conductor portion disposed within the #61 slot leading to the terminal605through the terminal lead509and extends circumferentially from the fourth layer conductor portion disposed in the #68 slot to the first neutral point N1through the terminal lead510.

The second phase winding11of the W-phase coil starts from the second layer conductor portion disposed within the #61 slot leading to the terminal606through the terminal lead511and extends circumferentially from the third layer conductor portion disposed in the #68 slot to the second neutral point N2through the terminal lead512.

The U-phase, V-phase, and W-phase coils are, as described above, identical in wiring pattern except for locations of the slots through which they pass, and reference will be made below only to the U-phase coil. The stator coil32has, like the above embodiments, the two slots350for each pole in each phase. Use of bridging conductors allows the stator coil32to have even slots more than two.

The first phase winding10of the U-phase coil extends from the first layer conductor portion disposed within the #29 slot, to the second layer conductor portion disposed within the #23 slot, to the third layer conductor portion disposed within the #29 slot, to the fourth layer conductor portion disposed within the #23 slot, to the first layer conductor portion disposed within the #17 slot, to the second layer conductor portion disposed within the #11 slot, to the third layer conductor portion disposed within the #23 slot, and to the fourth layer conductor portion disposed within the #11 slot, advances in a similar order, and then reaches the fourth layer conductor portion disposed within the #36 slot finally.

The first layer conductor portion disposed within the #29 slot is made of an I-shaped conductor used for a lead. Each of the second layer position disposed within the #23 slot and the third layer conductor portion disposed within the #29 slot is made of the lap winding segment35whose joint coil ends (i.e., welds) are located at the same position in the circumferential direction of the stator coil31. In other words, the joint coil ends are disposed at a zero pitch. Each of the fourth layer conductor portion disposed within the #23 slot and the first layer conductor portion disposed within the #17 slot is made of the wave winding segment34whose joint coil ends are located at an interval away from each other in the circumferential direction which is equivalent to an electrical angle of 2π (i.e., 2π slot pitch). The fourth layer conductor portion disposed within the #36 slot is made of an I-shaped conductor used for a lead. Specifically, the first phase winding10is made up of the lap winding segments35and the wave winding segments34joined alternately and has the I-shaped conductors at the ends thereof.

The second phase winding11of the U-phase coil extends from the second layer conductor portion disposed within the #29 slot, to the first layer conductor portion disposed within the #35 slot, to the fourth layer conductor portion disposed within the #41 slot, to the third layer conductor portion disposed within the #47 slot, to the second layer conductor portion disposed within the #41 slot, and to the first layer conductor portion disposed within the #47 slot, advances in a similar order, and then reaches the third layer conductor portion disposed within the #36 slot finally.

The second layer conductor portion disposed within the #29 slot is made of an I-shaped conductor used for a lead. Each of the first layer position disposed within the #35 slot and the fourth layer conductor portion disposed within the #41 slot is made of the wave winding segment34whose joint coil ends (i.e., welds) are located at an interval away from each other in the circumferential direction which is equivalent to an electrical angle of 2π (i.e., 2π slot pitch). Each of the third layer conductor portion disposed within the #47 slot and the second layer conductor portion disposed within the #41 slot is made of the lap winding segment35whose joint coil ends (i.e., welds) are located at the same position in the circumferential direction of the stator coil31. In other words, the joint coil ends are disposed at a zero pitch. The third layer conductor portion disposed within the #36 slot is made of an I-shaped conductor used for a lead. Specifically, the second phase winding11is made up of the lap winding segments35and the wave winding segments34joined alternately and has the I-shaped conductors at the ends thereof.

As apparent from the above discussion, the first and second phase windings10and11extend in opposite winding directions and have the ends disposed adjacent to each other within the same slots. The three-phase star-connected winding (i.e., the stator coil31) is, thus, made by connecting the first and second phase windings10and11in parallel to form each of the U-phase, V-phase, and W-phase coils. The first and second phase windings10and11may alternatively be connected in series to make either of a star-connection and a delta-connection of the U-phase, V-phase, and W-phase coils.

Arrangements of the terminal leads501to512, the terminals601to606, and the neutral points N1and N2are illustrated inFIGS. 45 and 46. The terminals of the same phase are located at a given interval away from each other for facilitating ease of connections with external terminals, however, may alternatively be located close to each other.

As apparent from the above discussion, each of the U-phase, V-phase, and W-phase coils is, like the above embodiments, made up of the first and second phase windings10and11whose pairs of terminal leads extend from the same slots, respectively, thus permitting conductors used to make windings10and11to be thinned. This facilitates ease of machining of such conductors and allows all the terminal leads to be bent simultaneously. Additionally, use of the two first and second windings10and11to make each of the U-phase, V-phase, and W-phase coils facilitates ease of switching between the serial and parallel connections thereof.

The stator coil31of the fifth embodiment in which the six slot-inserted portions633of the conductor segments33are disposed within each of the slots350to make the fractional pitch winding as the stator coil31may also be implemented, like the eighth embodiment, by a full-pitch winding.

A combination (s) of the first type of stator coil31in which the six slot-inserted portions of the conductor segments33are disposed within each of the slots350of the stator core32and the second type of stator coil31in which the four slot-inserted portions of the conductor segments33are disposed within each of the slots350of the stator core32may be provided on the stator core31to make the stator3. Alternatively, a plurality of either of the first type stator coils31and the second type stator coils331may be provided on the stator core31to make the stator3.