Patent Application
20100001609
The present invention relates to a rotating electric machine such as a motor and a generator. More particularly, the invention relates to a rotating electric machine preferably using rectangular wires as conducting wires for stator coils.
There are two types of stator coil windings: concentrated winding in which a wire is wound around each tooth in concentrated manner, and distributed winding in which a wire is wound over a plurality of slots and therefore coils of different phases or the same phase are overlapped each other at coil ends. With a concentrated-wound stator, coil ends can be downsized and therefore this type of stator is effective for downsizing a rotating electric machine and improving its efficiency. However, a rotating magnetic field generated on the inner circumference of the stator is not smoothly distributed resulting in a drawback that noise due to harmonics occurs. With a distributed-wound stator, on the other hand, a rotating magnetic field on the inner circumference of the stator can be approximated to a sine wave, making it possible to reduce noise more than the concentrated-wound stator. However, many coil portions are overlapped each other at coil ends and therefore the coil volume is larger than that of the concentrated-wound stator, making it difficult to downsize a rotating electric machine and improve its efficiency.
It is necessary for a drive main motor used in an electric vehicle to generate high power in spite of a limited mounting space and a limited battery voltage. There is a strong demand for downsizing and higher power at a remarkably high level. As means for meeting this demand, a method is known for increasing the coil occupation ratio in a stator slot by using rectangular copper wires having a rectangular cross section.
A known concentrated-wound stator coil using rectangular wires is disclosed, for example, in Patent Document 1 and Patent Document 2. It is comparatively easy to apply rectangular wires to the concentrated-wound stator because of its simple coil profile.
On the other hand, in the case of the distributed-wound stator coil using rectangular wires, it is necessary to avoid interference at coil ends while maintaining wire arrangements. As means for solving this problem, a two-layer coil is conventionally known (disclosed, for example, in Patent Document 3, Patent Document 4, and Patent Document 5). The two-layer coil is formed such that one coil piece inserted into a slot is disposed on the outer circumferential side of the slot and the other coil piece inserted into a slot is disposed on the inner circumferential side of the slot. Coil ends of adjacent slots are disposed above and below the two coil pieces of coil ends extending from the top to the slots, thus avoiding interference between different coils. The technique described in Patent Document 3 forms rectangular wires in a pine needle shape through bending, inserts the rectangular wires into slots from an axial end face of a stator core, and electrically connects open ends of rectangular conductor pieces protruded from the opposite end face of the stator core to configure a series-wound electric circuit. The techniques described in Patent Document 4 and Patent Document 5 form a coil referred to as “formed coil” conventionally used for medium- and large-size rotating electric machines for many years. The techniques wind a rectangular wire having a self-fusing layer in an oval shape, harden the whole winding, and twist coil ends to form a non-interference shape of the coil ends. Conductors constituting a coil are arranged in the same direction in slots and at the coil ends, and bonded to and in close contact with each other. With these conventional techniques, one coil wire in an electric circuit is associated with one rectangular wire, and the rectangular wires are arranged in the same direction with the same distance therebetween in the stator slots and at the coil ends.
However, the conventional distributed-wound stator using rectangular wires has a problem that the coil ends are not small enough to downsize a rotating electric machine. Further, the conventional distributed-wound stator using rectangular wires has a problem of insufficient heat radiation from coil ends.
An object of the present invention is to provide a compact, high-power rotating electric machine by downsizing coil ends on a distributed-wound stator using rectangular wires in comparison with the conventional one or by enhancing coil heat radiation from the coil ends or slot insertion portions.
(1) In order to attain the above-mentioned object, the present invention provides a rotating electric machine comprising a stator and a rotor disposed opposing the stator through a gap and held rotatably. The stator comprises a stator core, and stator coils inserted into stator slots formed between a plurality of stator teeth formed on the stator core, and wound around the stator teeth in the form of distributed winding. Each stator coil includes a plurality of rectangular wires having insulating coating, and the plurality of rectangular wires are inserted into the one stator slot. The direction of arrangement of the plurality of rectangular wires in the stator slot is different from that of the plurality of rectangular wires at both coil ends outside the stator slot.
This configuration makes it possible to downsize the coil ends or enhance coil heat radiation from coil ends or slot insertion portion.
(2) The rotating electric machine according to (1) above, wherein, preferably, the plurality of rectangular wires in the stator slot are arranged in the radial direction of the rotating electric machine such that the rectangular wires are in contact with each other, and wherein, preferably, the plurality of rectangular wires at the coil ends are arranged in the circumferential direction of the rotating electric machine such that the rectangular wires are in contact with each other.
(3) The rotating electric machine according to (2) above, wherein the stator slot is preferably a closed slot, and wherein the rectangular wires formed in a U shape are inserted from one end face of the stator slot and then connected with other rectangular wires protruded from an adjacent stator slot at the other end face of the stator slot to form a series wave winding.
(4) The rotating electric machine according to (2) above, wherein the stator slot is preferably an open slot, and wherein the rectangular wires are formed in a predetermined annular shape to configure a formed coil in advance, and the formed coil is inserted from an open portion of the stator slot to form a parallel winding.
(5) The rotating electric machine according to (1) above, wherein, preferably, the plurality of rectangular wires in the stator slot are arranged in the radial direction of the rotating electric machine such that the rectangular wires are in contact with each other, and wherein, preferably, the plurality of rectangular wires at the coil ends are arranged in the axial direction of the rotating electric machine such that the rectangular wires are spaced apart from each other.
(6) The rotating electric machine according to (5) above, wherein the stator slot is preferably a closed slot, and wherein the rectangular wires formed in a U shape are inserted from one end face of the stator slot and then connected with other rectangular wires protruded from an adjacent stator slot at the other end face of the stator slot to form a series wave winding.
(7) The rotating electric machine according to (5) above, wherein the stator slot is preferably an open slot, wherein the rectangular wires are formed in a predetermined annular shape to configure a formed coil in advance, and wherein the formed coil is inserted from an open portion of the stator slot to form a parallel winding.
(8) The rotating electric machine according to (1) above, wherein, preferably, a plurality of rectangular wires are connected in parallel.
(9) The rotating electric machine according to (1) above, wherein, preferably, the stator teeth have the same radial width, and wherein each of the plurality of rectangular wires inserted into the stator slot has the circumferential width, on the side closer to the rotor, smaller than that of a rectangular wire on the side further from the rotor.
(10) The rotating electric machine according to (3) or (6) above, wherein, preferably, the rectangular wires formed in a U shape are provided with a bonded portion, where the plurality of rectangular wires are bonded with each other and inserted into the stator slot.
(11) The rotating electric machine according to (10) above, wherein, preferably, the bonded portion is a resin-mold portion.
(12) The rotating electric machine according to (11) above, wherein, preferably, the bonded portion is disposed integrally with the resin-mold portion and provided with a thick portion for protecting a portion at which coil wires rise from the core end face.
The present invention makes it possible to downsize the coil ends, on a distributed-wound stator using rectangular coil wires, more than a conventional stator, or improve coil heat radiation from coil ends or slot insertion portions of the stator, thus obtaining a rotating electric machine with downsizing and higher power.
The configuration of a rotating electric machine according to a first embodiment of the present invention will be explained below with reference to
First of all, the overall configuration of the rotating electric machine according to the present embodiment will be explained below with reference to
As shown in
Although not shown, the stator 100 is attached to the inner circumference of a housing having a cylindrical shape. Front and rear brackets are attached at the front and rear ends of the housing, respectively. A bearing is attached at the center of the front bracket and at the center of the rear bracket. Both ends of the shaft 126 of the rotor 120 are rotatably supported by these bearings. Specifically, the rotor 120 is rotatably disposed on the side inward of the stator 110 such that a predetermined gap is provided therebetween.
As shown in
The configuration of a stator used for the rotating electric machine according to the present embodiment will be explained below with reference to
The stator core 112 includes a total of 48 slots: S1 to S48. Two stator coils are inserted into each slot. As a conducting wire of a stator coil 114, a rectangular wire having a rectangular cross-sectional profile and covered with insulating coating is used. The rectangular wire is formed in a U shape to form a conducting wire. Two ends of the U-shaped rectangular wire are inserted into two different slots. More specifically, each of the two ends of the rectangular wire is inserted from one end face of each of the two slots. At other end face of each slot, each end of the rectangular wire is connected through welding with one end of another conducting wire protruded from another slot.
Specifically, referring to
The present embodiment is characterized firstly in that the one conducting wire described above is constructed of a plurality of rectangular wires connected in parallel through a plurality of connections, and secondly in the way of arrangement of the plurality of rectangular wires.
As shown in
As shown in
With the present embodiment, inside a slot S, the rectangular wires C1-A, C1-B, and C1-C are arranged in a row in the radial direction of the stator (direction of an arrow A, that is, radial direction of the slot S) such that short sides of the three rectangular wires are in contact with each other. Therefore, the width W of the three rectangular wires C1-A, C1-B, and C1-C bundled together in a slot equals 8 mm which is the same as the width of one conventional rectangular wire (having a long side of 8 mm and a short side of 2 mm) inserted in a slot.
At a coil end, however, the rectangular wires C1-A, C1-B, and C1-C are arranged in a row in the circumferential direction of the stator (direction of an arrow B) such that long sides of the three rectangular wires are in contact with each other. As a result, as shown in
Specifically, when N rectangular wires connected in parallel are used instead of one conventional rectangular wire having a width W, and when the plurality of rectangular wires are arranged in the circumferential direction of the stator at the coil end, the width of the coil at the coil end equals W/N that can reduce the coil length at the coil end by (W−(W/N)).
Welding connection of the other ends will explained below with reference to
In accordance with the present embodiment as mentioned above, the length of the coil end can be reduced to shorten the axial length of the rotating electric machine, thus downsizing the rotating electric machine. Further, the use of a plurality of rectangular wires connected in parallel instead of one conventional rectangular wire can increase the total surface area of the rectangular wires, resulting in improvement in heat radiation from coil ends.
The use of three rectangular wires connected in parallel instead of one conventional rectangular wire can increase the surface area. Therefore, a current flowing on the surface can be increased making it possible to reduce high-frequency copper loss due to the skin effect.
The configuration of a rotating electric machine according to a second embodiment of the present invention will be explained below with reference to
As shown in
With the present embodiment, as shown in
Similar to the stator shown in
As shown in
At a coil end, however, the rectangular wires C1-A, C1-B, and C1-C are arranged in a row in the circumferential direction of the stator (direction of an arrow B) such that long sides of the three rectangular wires are in contact with each other. As a result, the width of the coil at the coil end equals the width of one rectangular wire, i.e., 2.66 mm. When one conventional rectangular wire is used, the width of the coil at the coil end is 8 mm. Therefore, the axial length of the stator at the coil end can be shortened by 5.34 mm, i.e., from 8 mm in a conventional stator to 2.66 mm in a stator according to the present embodiment.
Specifically, when N rectangular wires connected in parallel are used instead of one conventional rectangular wire having a width W, and when the plurality of rectangular wires are arranged in the circumferential direction of the stator, the width of the coil at the coil end equals W/N that can reduce the coil length at the coil end by (W−(W/N)).
In accordance with the present embodiment as mentioned above, the length of the coil end can be reduced to shorten the axial length of the rotating electric machine, thus downsizing the rotating electric machine. Further, the use of a plurality of rectangular wires connected in parallel instead of one conventional rectangular wire can increase the total surface area of the rectangular wires, resulting in improvement in heat radiation from coil ends.
The configuration of a rotating electric machine according to a third embodiment of the present invention will be explained below with reference to
The present embodiment is applied to the closed slot of
As shown in
As shown in
With the present embodiment, inside a slot S, the rectangular wires C1-A, C1-B, and C1-C are arranged in a row in the radial direction of the stator (direction of an arrow A, that is, radial direction of the slot S) such that short sides of the three rectangular wires are in contact with each other. Therefore, the width W of the three rectangular wires C1-A, C1-B, and C1-C bundled together in the slot equals 8 mm which is the same as the width of one conventional rectangular wire (having a long side of 8 mm and a short side of 2 mm) inserted in the slot.
As shown in
In this way, since the surface area of the rectangular wires at the coil end is increased and a coolant passes through gaps between the rectangular wires, heat radiation from coil ends on the connection side is improved.
Welding connection of the other ends will be explained below with reference to
The open ends of the rectangular wires protruded from the end face of the stator are arranged so as not to be circumferentially overlapped with each other when viewed from the radial direction (direction of an arrow A) by providing a different length (path) from a slot to the end for each wire.
As a result, since the surface area of the rectangular wires at the coil end is increased, and a coolant passes through gaps between the rectangular wires formed between each slot and the connecting portion, heat radiation from coil ends on the connection side is improved.
In accordance with the present embodiment as mentioned above, the use of a plurality of rectangular wires instead of one conventional rectangular wire can increase the total surface area of the rectangular wires, resulting in improvement in heat radiation from coil ends. Further, at the coil end, a gap formed between adjacent rectangular wires further improves heat radiation.
The configuration of a rotating electric machine according to a fourth embodiment of the present invention will be explained below with reference to
The present embodiment is applied to the open slot explained in
Similar to
Similar to the example of
At a coil end, however, the rectangular wires are disposed so as to be spaced apart from each other with a gap therebetween in the axial direction of the stator. In this way, since the surface area of the rectangular wires at the coil end is increased and a coolant passes through gaps between the rectangular wires, heat radiation from coil ends on the connection side is improved.
In accordance with the present embodiment as mentioned above, the use of a plurality of rectangular wires instead of one conventional rectangular wire can increase the total surface area of the rectangular wires, resulting in improvement in heat radiation from coil ends. Further, at the coil end, a gap formed between adjacent rectangular wires further improves heat radiation.
The configuration of a rotating electric machine according to a fifth embodiment of the present invention will be explained below with reference to
The present embodiment is applied to the open slot explained in
As shown in
Here, when a coil is configured with rectangular wires having the same cross-sectional profile, the stator slot has a rectangular shape and therefore each of teeth 9 has a larger width on the outer circumferential side. However, since a magnetic path width necessary to satisfy the required performance of the rotating electric machine is the teeth width on the inner circumferential side, the core used on the outer circumferential side is excessive.
On the contrary, with the coil structure as shown in
The configuration of a rotating electric machine according to a sixth embodiment of the present invention will be explained below with reference to
The present embodiment is applied to the closed slot explained in
As shown in
As shown in
Then, the two slot insertion pieces are grasped and then opened in the circumferential direction of the stator, thus obtaining a stator coil for series wave winding. Only the slot insertion portions of the coil formed by arranging the rectangular wires in a row are bonded, and then the two slot insertion pieces are grasped and opened in the circumferential direction of the stator, thus obtaining a stator coil for parallel winding.
As explained above, the slot insertion portions are bonded to improve heat transmission between the rectangular wires and heat transmission from the coil inside the slot to the stator core resulting in improved heat radiation of the coil. Further, since a plurality of rectangular wires can be handled as one coil wire, it becomes easier to assemble the core and coils.
The configuration of a rotating electric machine according to a seventh embodiment of the present invention will be explained below with reference to
The present embodiment is applied to the closed slot explained in
In the present embodiment, the slot insertion portions of the three rectangular wires are unified such that the slot insertion portions are wrapped with a mold block, and then resin is poured into the mold block to mold the resin in a cross-sectional profile slightly smaller than the cross-sectional profile of a slot, resulting in formation of a resin-molded portion 10.
Also in accordance with the present embodiment, the slot insertion portions are bonded to improve heat transmission between the rectangular wires and heat transmission from the coil inside the slot to the stator core resulting in improved heat radiation of the coil. Further, since a plurality of rectangular wires can be handled as one coil wire, it becomes easier to assemble the core and coils.
The configuration of a rotating electric machine according to an eighth embodiment of the present invention will be explained below with reference to
The present embodiment is applied to the closed slot explained in
In the present embodiment, as the same way as the example of
This method provides a higher strength than the insulated paper conventionally used. Therefore, even when the bending radius of the portion at which the coil wires rise from the slot is decreased to form the coil end low, the insulation between the core and the coil can be ensured.
The present embodiment can be applied only to the coil end on the side bended in a U shape in the closed-slot stator coil type, and applied to both coil ends in the open-slot stator coil type.
Also in accordance with the present embodiment, the slot insertion portions are bonded to improve heat transmission between the rectangular wires and heat transmission from the coil inside the slot to the stator core resulting in improved heat radiation of the coil. Further, since a plurality of rectangular wires can be handled as one coil wire, it becomes easier to assemble the core and coils. Further, the insulation between the core and the coil can be ensured even when the coil end is formed low.
The configuration of a hybrid vehicle mounting a rotating electric machine according to each embodiment of the present invention will be explained below with reference to
The hybrid vehicle includes an engine ENG and a rotating electric machine (motor generator (M/G)) as sources of driving force. The motor generator M/G has the configuration explained in
The hybrid vehicle of the present embodiment is provided with an idle stop mechanism which stops the engine ENG when the vehicle stops at a crossing or the like. When the vehicle runs again and the amount of accelerator depression, etc. is detected, the motor control unit MCU controls the inverter INV to operate the motor generator M/G as a motor to rotate the wheels by the driving force, and restarts the engine ENG. After the engine ENG is restarted, the motor generator M/G stops. Further, at the time of deceleration, etc., the motor control unit MCU controls the inverter INV to operate the motor generator M/G as a generator, converts the generated electric power to DC electric power, and accumulates the DC electric power in the battery BA.
As mentioned above, since the rotating electric machine according to the present embodiment is compact and highly efficient, the fuel consumption of the hybrid vehicle can be reduced.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2006/316038 | 8/15/2006 | WO | 00 | 1/8/2009 |
