Stator of rotating electrical machine for vehicle

A first U-shaped part that is bent so as to form a pair of opposite surfaces facing each other, and a second U-shaped part that is bent so as to form a pair of opposite surfaces facing each other are provided side by side in a bus bar main body of a neutral conductor bus bar. One of the first pair of opposite surfaces and one of the second pair of opposite surfaces are located in the same plane, and the other of the first pair of opposite surfaces and the other of the second pair of opposite surfaces are located in the same plane. A temperature sensor is retained by being inserted through a gap between the first pair of opposite surfaces and a gap between the second pair of opposite surfaces.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Japanese Patent Application No. 2020-080807 filed on Apr. 30, 2020, incorporated herein by reference in its entirety.

BACKGROUND

1. Technical Field

The present disclosure relates to a stator of a rotating electrical machine for a vehicle including a temperature sensor that measures the temperature in a bus bar connected to a coil.

2. Description of Related Art

There are known stators of rotating electrical machines for vehicles in which a bus bar is provided with a bent part and a temperature sensor is retained inside the bent part. One example is the stator described in Japanese Patent Application Publication No. 2019-110676 (JP 2019-110676 A).

SUMMARY

To increase the measurement accuracy of the temperature in a bus bar, a heat receiving area of a temperature sensor that receives heat from the bus bar needs to be increased. Increasing the heat receiving area of the temperature sensor in the stator of a rotating electrical machine for a vehicle described in JP 2019-110676 A requires increasing the width of the bus bar that comes into contact with the temperature sensor on the inner side of the bent part. However, increasing the width of the bus bar increases the size of the bus bar.

Having been devised in view of this situation, the present disclosure aims to provide a stator of a rotating electrical machine for a vehicle that makes it possible to increase the heat receiving area of a temperature sensor that receives heat from a bus bar, without increasing the width of the bus bar, to maintain the measurement accuracy of the temperature in the bus bar.

The gist of a first aspect is as follows: A stator of a rotating electrical machine for a vehicle, the stator including: a coil wound around a stator core having a cylindrical shape centered on an axis; a bus bar connected to the coil; and a temperature sensor that measures the temperature in the bus bar, wherein: (a) the bus bar has a bus bar main body that is extended into an elongated shape, and a connection terminal that connects the bus bar main body and the coil to each other; (b) a first bent part that is bent so as to form a pair of first opposite surfaces facing each other, and a second bent part that is bent so as to form a pair of second opposite surfaces facing each other are provided side by side in the bus bar main body; (c) one of the pair of first opposite surfaces and one of the pair of second opposite surfaces are located in the same plane, and the other of the pair of first opposite surfaces and the other of the pair of second opposite surfaces are located in the same plane; and (d) the temperature sensor is retained by being inserted through a gap between the pair of first opposite surfaces and a gap between the pair of second opposite surfaces.

The gist of a second aspect is that, in the first aspect: (a) the bus bar main body is extended into an elongated shape in a circumferential direction of the stator core; and (b) the first bent part and the second bent part are extended toward the outer circumferential side in a radial direction of the stator core and then bent toward the inner circumferential side in the radial direction.

The gist of a third aspect is that, in the second aspect, the first bent part and the second bent part are each bent into a U-shape in a plane including the axis.

The gist of a fourth aspect is that, in the second or third aspect: (a) a thickness direction of the bus bar main body is a direction parallel to the axis; and (b) the connection terminal has a structure of being extended from the bus bar main body toward the inner circumferential side in the radial direction and then bent in a direction parallel to the axis.

The gist of a fifth aspect is that, in any one of the first to fourth aspects: (a) a coupling part that is bent into a U-shape and couples the first bent part and the second bent part to each other is formed between the first bent part and the second bent part; (b) the coupling part has a connection surface that is located in the same plane as those of the pair of first opposite surfaces and the pair of second opposite surfaces that are located on the side of the coupling part; and (c) the temperature sensor is in contact with the connection surface.

The gist of a sixth aspect is that, in the fifth aspect, the area of a cross-section of each of the first bent part, the second bent part, and the coupling part cut along a width direction is equal to the area of a cross-section of the bus bar main body cut along a width direction.

The gist of a seventh aspect is that, in any one of the first to sixth aspects: (a) the coil is one of Y-connected three-phase coils; and (b) the bus bar main body is a neutral conductor of the coil.

According to the stator of a rotating electrical machine for a vehicle of the first aspect, (a) the bus bar has the bus bar main body that is extended into an elongated shape, and the connection terminal that connects the bus bar main body and the coil to each other; (b) the first bent part that is bent so as to form the pair of first opposite surfaces facing each other, and the second bent part that is bent so as to form the pair of second opposite surfaces facing each other are provided side by side in the bus bar main body; (c) one of the pair of first opposite surfaces and one of the pair of second opposite surfaces are located in the same plane, and the other of the pair of first opposite surfaces and the other of the pair of second opposite surfaces are located in the same plane; and (d) the temperature sensor is retained by being inserted through the gap between the pair of first opposite surfaces and the gap between the pair of second opposite surfaces. Thus, the temperature sensor is retained by being inserted through the gap between each of the pair of first opposite surfaces and the pair of second opposite surfaces, i.e., more than one gap. Compared with when the temperature sensor is retained by being inserted through a single gap, the heat receiving area of the temperature sensor that receives heat from the bus bar can be increased to maintain the measurement accuracy of the temperature in the bus bar. For example, having a large heat receiving area, the temperature sensor can achieve high responsiveness to changes in the temperature of the bus bar in temperature measurement. Moreover, having a large heat receiving area, the temperature sensor is likely to maintain robustness in measurement accuracy even when the mounting position of the temperature sensor deviates to some extent in the insertion direction while the temperature sensor is mounted so as to be retained by being inserted through the gap between the pair of first opposite surfaces and the gap between the pair of second opposite surfaces in the bus bar main body.

According to the stator of a rotating electrical machine for a vehicle of the second aspect, in the first aspect, (a) the bus bar main body is extended into an elongated shape in the circumferential direction of the stator core, and (b) the first bent part and the second bent part are extended toward the outer circumferential side in the radial direction of the stator core and then bent toward the inner circumferential side in the radial direction. The gap between the pair of first opposite surfaces formed by the first bent part and the gap between the pair of second opposite surfaces formed by the second bent part both open in the circumferential direction of the stator core. This allows the temperature sensor to be inserted along the circumferential direction in which these gaps open, which can increase the efficiency with which the temperature sensor is mounted to the bus bar.

According to the stator of a rotating electrical machine for a vehicle of the third aspect, in the second aspect, the first bent part and the second bent part are each bent into a U-shape in a plane including the axis. Surfaces through which the temperature sensor can receive heat from the bus bar include, other than the pair of first opposite surfaces and the pair of second opposite surfaces, inner surfaces of the first bent part and the second bent part that are bent into a U-shape. Thus, the temperature sensor can receive more heat from the bus bar and maintain the measurement accuracy of the temperature in the bus bar.

According to the stator of a rotating electrical machine for a vehicle of the fourth aspect, in the second or third aspect, (a) the thickness direction of the bus bar main body is a direction parallel to the axis, and (b) the connection terminal has a structure of being extended from the bus bar main body toward the inner circumferential side in the radial direction and then bent in a direction parallel to the axis. The connection terminal has a structure of being extended from the bus bar main body toward the inner circumferential side in the radial direction of the stator core and then bent only at one part in a direction parallel to the axis of the stator core. Thus, the distance between the bus bar main body and the connection terminal in the radial direction can be reduced to keep the size of the bus bar down.

According to the stator of a rotating electrical machine for a vehicle of the fifth aspect, in any one of the first to fourth aspects, (a) the coupling part that is bent into a U-shape and couples the first bent part and the second bent part to each other is formed between the first bent part and the second bent part; (b) the coupling part has the connection surface that is located in the same plane as those of the pair of first opposite surfaces and the pair of second opposite surfaces that are located on the side of the coupling part; and (c) the temperature sensor is in contact with the connection surface. Surfaces through which the temperature sensor can receive heat from the bus bar include, other than the pair of first opposite surfaces and the pair of second opposite surfaces, the connection surface of the coupling part. Thus, the temperature sensor can receive more heat from the bus bar and maintain the measurement accuracy of the temperature in the bus bar.

According to the stator of a rotating electrical machine for a vehicle of the sixth aspect, in the fifth aspect, the area of the cross-section of each of the first bent part, the second bent part, and the coupling part cut along the width direction is equal to the area of the cross-section of the bus bar main body cut along the width direction. This allows a current to flow through the bus bar at the same current density in the first bent part, the second bent part, and the coupling part and in the bus bar main body. As a result, the bus bar is likely to generate an equal amount of heat at parts in the longitudinal direction, including the first bent part, the second bent part, and the coupling part, which helps maintain the measurement accuracy of the temperature in the bus bar.

According to the stator of a rotating electrical machine for a vehicle of the seventh aspect, in any one of the first to sixth aspects, (a) the coil is one of Y-connected three-phase coils, and (b) the bus bar main body is a neutral conductor of the coil. Heat generated in each coil of the Y-connected three-phase coils is conducted to the neutral conductor bus bar from one end of the coil. Therefore, the temperature sensor retained by the neutral conductor bus bar can accurately measure the temperature of the coil wound around the stator core.

DETAILED DESCRIPTION OF EMBODIMENTS

An embodiment of the present disclosure will be described in detail below with reference to the drawings. The drawings in the embodiment to be described below are simplified or modified as necessary to help understand the present disclosure and do not necessarily exactly represent the dimensional ratios, shapes, etc. of parts.

FIG.1is a view illustrating the circuit configuration of a stator10of a rotating electrical machine MG for a vehicle according to the embodiment of the present disclosure. The stator10has Y-connected three-phase coils16U,16V,16W. One end of each of the three-phase coils16U,16V,16W is connected to a neutral conductor bus bar30. The other ends of the three-phase coils16U,16V,16W are respectively connected to external terminals26U,26V26W through terminal bus bars18U,18V,18W and power lines24U,24V,24W (seeFIG.2). The coils16U,16V,16W are coils of the respective phases in a three-phase three-coil configuration, for example, a U-phase, a V-phase, and a W-phase. For example, when the rotating electrical machine MG for a vehicle is driven to rotate, a three-phase alternating current is input into the external terminals26U,26V,26W. Hereinafter, unless it is necessary to make distinctions among the coils16U,16V,16W according to the phase, these coils will be referred to simply as the “coils16.” One of the Y-connected three-phase coils16U,16V,16W corresponds to the “coil” in the present disclosure, and the neutral conductor bus bar30corresponds to the “bus bar” in the present disclosure.

FIG.2is a perspective view of the stator10of the rotating electrical machine MG for a vehicle shown inFIG.1, in a state where a temperature sensor50that measures the temperature of the neutral conductor bus bar30is retained.

The stator10includes a stator core20, the coils16, the neutral conductor bus bar30, and the temperature sensor50.

The stator core20has a cylindrical shape centered on an axis CL that is formed by stacking, for example, a plurality of magnetic steel sheets. An inner circumferential surface of the cylindrical stator core20is provided with a plurality of grooves, i.e., slots12, each of which has a depth in a direction toward an outer circumferential direction in a radial direction centered on the axis CL and extends through the stator core20in a direction parallel to the axis CL. Hereinafter, the radial direction centered on the axis CL will be referred to simply as the “radial direction,” and the direction parallel to the axis CL will be referred to simply as the “direction of the axis CL.” Teeth14are each formed between adjacent slots12. The coils16are wound around the teeth14of the stator core20. The stator core20is not necessarily limited to being formed by magnetic steel sheets but may instead be formed by, for example, molding a powdered or solid magnetic material.

The coil16is formed by, for example, inserting a plurality of substantially U-shaped segment coils into the slots12and then electrically connecting end portions of the segment coils that protrude from the slots12to an outside of the stator core20by welding. The segment coils are so-called flat conductors having a rectangular cross-section like elongated conductor plates, with insulation coating, such as enamel coating, applied to surfaces. Portions of the coil16that protrude from the slots12to the outside of the stator core20are coil ends22.

As described above, the power lines24U,24V,24W respectively connect the terminal bus bars18U,18V,18W and the external terminals26U,26V26W to each other.

The neutral conductor bus bar30is extended into an arc shape in the circumferential direction centered on the axis CL, and electrically connects the one end, i.e., the end on the side of the neutral conductor, of each of the Y-connected three-phase coils16. Thus, the neutral conductor bus bar30is a neutral conductor of the Y-connected three-phase coils16. The temperature sensor50that measures the temperature in the neutral conductor bus bar30is retained by the neutral conductor bus bar30. Hereinafter, the circumferential direction centered on the axis CL will be referred to simply as the “circumferential direction.”

FIG.3is a perspective view of the neutral conductor bus bar30shown inFIG.2. The first direction, the second direction, and the third direction shown inFIG.3are respectively a direction parallel to the axis CL in a bent part36provided in a bus bar main body32to be described later, a radial direction in the bent part36, and a direction of a tangent to the circumferential direction centered on the axis CL at the bent part36. The arrow directions of the first direction, the second direction, and the third direction indicate one side in the first direction, the second direction, and the third direction, and the directions opposite from these arrows indicate the other side in the first direction, the second direction, and the third direction. The one side in the second direction is an outer circumferential side in the radial direction of the bent part36, and the other side in the second direction is an inner circumferential side in the radial direction of the bent part36. The first direction, the second direction, and the third direction are perpendicular to one another. The first direction, the second direction, and the third direction shown inFIG.2described above andFIG.4toFIG.7to be described later are the same as those shown inFIG.3.

The neutral conductor bus bar30has the bus bar main body32having an arc shape with the center of curvature located on the axis CL, and connection terminals34U,34V,34W. Hereinafter, unless it is necessary to make distinctions among the connection terminals34U,34V,34W according to the phase, these connection terminals will be referred to simply as the “connection terminals34.” The bus bar main body32and the connection terminals34are integrally formed.

The bus bar main body32is an elongated conductor that is extended in the circumferential direction and has, for example, a rectangular shape in cross-section. In a cross-section of the bus bar main body32perpendicular to an extension direction, the shorter distance between opposite surfaces is the thickness of the bus bar main body32, and the longer distance between opposite surfaces is the width of the bus bar main body32. A longitudinal direction, a thickness direction, and a width direction of the bus bar main body32lie in the circumferential direction, the direction of the axis CL, and the radial direction, respectively.

The bus bar main body32is provided with the bent part36. The bus bar main body32and the bent part36are integrally formed. The bent part36includes a first U-shaped part40that is bent so as to form a pair of opposite surfaces40a,40bfacing each other, and a second U-shaped part42that is bent so as to form a pair of opposite surfaces42a,42bfacing each other (seeFIG.4AandFIG.7B). The first U-shaped part40and the second U-shaped part42are provided adjacent to each other in the third direction, i.e., side by side in the third direction.

The first U-shaped part40and the second U-shaped part42are extended toward the one side in the second direction (the outer circumferential side in the radial direction) and then bent toward the other side in the second direction (the inner circumferential side in the radial direction), so as to be bent into a U-shape in a plane including the axis CL. The first U-shaped part40has an inner circumferential surface40c(seeFIG.4AandFIG.7B) that is an inner surface of the U-shaped part, and the pair of opposite surfaces40a,40bthat face each other across a gap40gin the first direction. The second U-shaped part42has an inner circumferential surface42c(seeFIG.4A) that is an inner surface of the U-shaped part, and the pair of opposite surfaces42a,42bthat face each other across a gap42gin the first direction. One opposite surface40aof the pair of opposite surfaces40a,40band one opposite surface42aof the pair of opposite surfaces42a,42bare located in the same plane, and the other opposite surface40bof the pair of opposite surfaces40a,40band the other opposite surface42bof the pair of opposite surfaces42a,42bare located in the same plane. The first U-shaped part40and the second U-shaped part42correspond to the “first bent part” and the “second bent part,” respectively, in the present disclosure. The pair of opposite surfaces40a,40band the pair of opposite surfaces42a,42bcorrespond to the “pair of first opposite surfaces” and the “pair of second opposite surfaces,” respectively, in the present disclosure.

One end portion of the first U-shaped part40is bent toward the side opposite from the second U-shaped part42, while the other end portion thereof is bent toward the second U-shaped part42. One end portion of the second U-shaped part42is bent toward the side opposite from the first U-shaped part40, while the other end portion thereof is bent toward the first U-shaped part40. The other end portion of the first U-shaped part40and the other end portion of the second U-shaped part42are coupled together by a coupling part38. The coupling part38is bent into a U-shape in a plane orthogonal to the axis CL. Thus, between the first U-shaped part40and the second U-shaped part42, the coupling part38is formed that is bent into a U-shape in a plane orthogonal to the axis CL and couples the first U-shaped part40and the second U-shaped part42together. The coupling part38has a connection surface38a(seeFIG.7B) that is located in the same plane as those opposite surfaces40b,42bof the pair of opposite surfaces40a,40band the pair of opposite surfaces42a,42bthat are located on the side of the coupling part38, and connects these opposite surfaces40b,42bto each other (seeFIG.7B).

The area of a cross-section of each of the first U-shaped part40, the second U-shaped part42, and the coupling part38cut along a width direction is equal to the area of a cross-section of the bus bar main body32cut along a width direction. In a cross-section of each of the first U-shaped part40, the second U-shaped part42, and the coupling part38perpendicular to an extension direction of that part, the shorter distance between opposite surfaces is the thickness of the first U-shaped part40, the second U-shaped part42, or the coupling part38, and the longer distance between opposite surfaces is the width of the first U-shaped part40, the second U-shaped part42, or the coupling part38.

The connection terminals34are terminals for connecting the bus bar main body32and the one end of each of the three-phase coils16to each other. In the circumferential direction, the neutral conductor bus bar30has the connection terminal34U provided on the side of the one end of the bus bar main body32, the connection terminal34W provided on the side of the other end of the bus bar main body32, and the connection terminal34V provided at a central part of the bus bar main body32. The connection terminals34U,34V,34W have a structure of being extended from the bus bar main body32toward the other side in the second direction (the inner circumferential side in the radial direction) and then bent toward the one side in the first direction.

FIG.4Ais a view showing one example of a method to form the neutral conductor bus bar30shown inFIG.3, in a state after punching by a press die is performed, andFIG.4Bis a view showing the method, in a state after bending by the press die is performed and the neutral conductor bus bar30is formed.FIG.4AandFIG.4Bare plan views as seen from the one side in the first direction. Reference numerals corresponding to the parts inFIG.4Bthat shows the state after the neutral conductor bus bar30is formed are indicated at the same positions inFIG.4A.

First, a member shaped as shown inFIG.4Ais punched out of, for example, a sheet material having a predetermined thickness by punching (shearing). The member punched out has an arc-shaped part (a part to be processed into the bus bar main body32) and parts protruding from the arc-shaped part toward the inner circumferential side in the radial direction (parts to be processed into the connection terminals34U,34V,34W). Further, the arc-shaped part is provided with parts that extend parallel to each other toward the outer circumferential side in the radial direction (parts to be processed into the first U-shaped part40and the second U-shaped part42), and a part that connects leading end portions of these parts that extend parallel to each other into a U-shape (a part to be processed into the coupling part38). Punching is a process of punching a member out of a sheet material by generating shearing stress in metal using punching tools, such as a die and a punch, so as to apply a load exceeding the elastic limit of the material.

Next, those parts of the member shaped as shown inFIG.4Athat protrude from the arc-shaped part toward the inner circumferential side in the radial direction are bent along bending lines BL1to BL3so as to extend toward the upper side of the sheet ofFIG.4A(the one side in the first direction). As a result, the connection terminals34U,34V,34W having a structure of being extended from the bus bar main body32toward the inner circumferential side in the radial direction and then bent in a direction parallel to the axis CL are formed.

Further, those parts of the member shaped as shown inFIG.4Athat are provided in the arc-shaped part and extend parallel to each other toward the outer circumferential side in the radial direction, and the part of the member that connects the leading end portions of those parts to each other are bent along a bending line BL4into a U-shape such that the part connecting the leading end portions to each other is located on the inner circumferential side in the radial direction. As a result, the bent part36including the first U-shaped part40and the second U-shaped part42that are bent into a U-shape, and the coupling part38is formed. Thus, the first U-shaped part40and the second U-shaped part42are bent in the same direction along the bending line BL4, and the first U-shaped part40and the second U-shaped part42are provided adjacent to each other in the third direction, i.e., side by side in the third direction. The first U-shaped part40and the second U-shaped part42are extended from the bus bar main body32toward the outer circumferential side in the radial direction, and are then bent along the bending line BL4toward the upper side of the sheet ofFIG.4A(the one side in the first direction) and further bent toward the inner circumferential side in the radial direction so as to form a U-shape. Bending along the bending line BL4can be achieved by one processing. Since the first U-shaped part40, the second U-shaped part42, and the connection terminals34U,34V,34W are bent from the bus bar main body32toward the same upper side of the sheet ofFIG.4A(the one side in the first direction), the size of the neutral conductor bus bar30in the first direction can be reduced.

Thus, the neutral conductor bus bar30can be manufactured by punching a sheet material by a press die and then bending the obtained member by the press die, and therefore can be inexpensively manufactured.

FIG.5is a perspective view of the temperature sensor50shown inFIG.2. The temperature sensor50includes a case52, a temperature detection element60, and lead wires64. InFIG.5, the shape of the temperature sensor50is indicated by solid lines and dashed lines, and a rough position where the temperature detection element60is housed is indicated by a long dashed double-short dashed line.

The case52has a substantially L-shape and has a main part54and a sub-part58.

The main part54has a rectangular parallelepiped shape that is extended so as to be elongated in the third direction. In the third direction, the main part54has an insertion portion54aon one side and an extended portion54bon the other side. The main part54is provided with a first projection56a, a second projection56b, and a third projection56c.

The first projection56ais provided on an end surface of the insertion portion54aon the one side in the third direction, and projects from a part of this end surface on the one side in the second direction toward the one side in the third direction. The second projection56bis provided on an end surface of the extended portion54bon the one side in the second direction, and projects from this end surface toward the one side in the second direction as well as toward the other side in the first direction. The third projection56cis provided on an end surface of the insertion portion54aon the other side in the second direction, and projects from this end surface toward the other side in the second direction, and further projects from the projected position toward the one side in the first direction.

The insertion portion54ais a portion of the main part54that is located between the first projection56aand the second projection56bin the third direction, and between the second projection56band the third projection56cin the second direction. The thickness of the insertion portion54ain the first direction is substantially equal to the dimension of the gap40gin the pair of opposite surfaces40a,40band the gap42gbetween the pair of opposite surfaces42a,42b. The width of the insertion portion54ain the second direction is set such that the insertion portion54acomes into contact with the connection surface38aof the coupling part38when the temperature sensor50is inserted through the gap40gand the gap42gas will be described later. The extended portion54bis a portion of the main part54other than the insertion portion54a, the first projection56a, the second projection56b, and the third projection56c.

The sub-part58has a rectangular parallelepiped shape that is extended from the other side of the main part54in the third direction toward the other side in the first direction so as to be elongated. The sub-part58is provided on end surfaces of the extended portion54band the second projection56bon the other side in the first direction, and projects toward the other side in the first direction from a part of this end surface on the one side in the second direction.

The temperature detection element60is housed inside the insertion portion54aof the case52. Two lead wires64through which output signals indicating the temperature detected by the temperature detection element60are output are led out of the case52through holes provided in the sub-part58, on the other side in the first direction. The two lead wires64are bundled into a wire harness66outside the case52. A wire harness is a plurality of electric wires bundled together like the two lead wires64to allow easy installation in an automobile assembly line.

FIG.6is a view illustrating a method to retain the temperature sensor50in this embodiment.FIG.6Ashows a state before the temperature sensor50is inserted through the gaps40g,42gformed by the first U-shaped part40and the second U-shaped part42, respectively, of the neutral conductor bus bar30, andFIG.6Bshows a state after the temperature sensor50is inserted and retained.

The connection terminals34U,34V,34W of the neutral conductor bus bar30are each electrically connected by welding, for example, to the one end, i.e., the end on the side of the neutral conductor, of the corresponding one of the Y-connected three-phase coils16U,16V,16W. This connection results in a state where the gap40gbetween the pair of opposite surfaces40a,40bof the first U-shaped part40and the gap42gbetween the pair of opposite surfaces42a,42bof the second U-shaped part42both open in the circumferential direction (to be exact, in the third direction).

Next, the temperature sensor50is inserted through the gap40gand the gap42gin the direction of the outlined arrow shown inFIG.6A. Thus, the insertion portion54ahousing the temperature detection element60in the temperature sensor50is retained by being held between the pair of opposite surfaces40a,40bas well as between the pair of opposite surfaces42a,42b, which results in the state shown inFIG.6B. The temperature sensor50is retained so as to be in contact with the connection surface38aof the coupling part38.

As shown inFIG.6B, in the state where the temperature sensor50is retained by being inserted through the gaps40g,42gformed by the first U-shaped part40and the second U-shaped part42, respectively, of the neutral conductor bus bar30, the temperature sensor50is prevented from moving relatively to the neutral conductor bus bar30as follows.

Since the insertion portion54aof the temperature sensor50is held between the pair of opposite surfaces40a,40bof the first U-shaped part40and the pair of opposite surfaces42a,42bof the second U-shaped part42, the temperature sensor50is prevented from moving relatively to the neutral conductor bus bar30in the first direction. As the third projection56cof the temperature sensor50hits against an end surface of the coupling part38of the neutral conductor bus bar30on the other side in the second direction, the temperature sensor50is prevented from moving relatively to the neutral conductor bus bar30toward the one side in the second direction. As the sub-part58of the temperature sensor50hits against an end surface of the bus bar main body32of the neutral conductor bus bar30on the one side in the second direction, the temperature sensor50is prevented from moving relatively to the neutral conductor bus bar30toward the other side in the second direction. As the second projection56bof the temperature sensor50hits against an end surface of the first U-shaped part40of the neutral conductor bus bar30on the other side in the third direction, the temperature sensor50is prevented from moving relatively to the neutral conductor bus bar30toward the one side in the third direction.

Thus, relative movement of the temperature sensor50relative to the neutral conductor bus bar30is limited, and the temperature sensor50is temporarily fixed to the neutral conductor bus bar30. In this state where the temperature sensor50is temporarily fixed to the neutral conductor bus bar30, the neutral conductor bus bar30and the temperature sensor50are fixed with resin. The configuration of this fixation with resin may be such that, in addition to the neutral conductor bus bar30and the temperature sensor50, the coil ends22are fixed with resin along the entire circumference of the stator core20in the circumferential direction, or such that the neutral conductor bus bar30and the temperature sensor50are fixed with resin at part of the stator core20in the circumferential direction. As the neutral conductor bus bar30and the temperature sensor50are fixed with resin, the temperature sensor50is prevented also from moving relatively to the neutral conductor bus bar30toward the other side in the third direction. Thus, the temperature sensor50is prevented from moving relatively to the neutral conductor bus bar30in all directions, and the temperature sensor50is completely fixed to the neutral conductor bus bar30.

FIG.7AtoFIG.7Care views illustrating the state shown inFIG.6Bwhere the temperature sensor50is retained by being inserted through the gaps40g,42gformed by the first U-shaped part40and the second U-shaped part42, respectively, of the neutral conductor bus bar30.FIG.7Ais a view as seen from the one side in the first direction (the direction parallel to the axis CL), andFIG.7BandFIG.7Care sectional views taken along lines b-b and c-c, as seen from the other side in the third direction. InFIG.7AtoFIG.7C, the neutral conductor bus bar30is indicated by solid lines and dashed lines, and for reference, the temperature sensor50is indicated by long dashed short dashed lines and the rough housing position of the temperature detection element60is indicated by long dashed double-short dashed lines. The cutting-plane line b-b and the cutting-plane line c-c shown inFIG.7Aare respectively the cutting-plane line of the sectional view ofFIG.7Band the cutting-plane line of the sectional view ofFIG.7C.

As shown inFIG.7AtoFIG.7C, the insertion portion54aof the temperature sensor50where the temperature detection element60is housed is retained in a state of being in contact with or close to the pair of opposite surfaces40a,40bof the first U-shaped part40and the pair of opposite surfaces42a,42bof the second U-shaped part42by being held between these pairs of opposite surfaces. Thus, the insertion portion54aof the temperature sensor50is in contact or substantially in contact with the pair of opposite surfaces40a,40bof the first U-shaped part40and the pair of opposite surfaces42a,42bof the second U-shaped part42. Therefore, the temperature sensor50receives heat of the neutral conductor bus bar30from each of the pair of opposite surfaces40a,40bof the first U-shaped part40and the pair of opposite surfaces42a,42bof the second U-shaped part42. Further, the temperature sensor50receives heat of the neutral conductor bus bar30also from the inner circumferential surface40cof the first U-shaped part40and the inner circumferential surface42cof the second U-shaped part42. The insertion portion54aof the temperature sensor50is in contact with the connection surface38aof the coupling part38. Therefore, the temperature sensor50receives heat of the neutral conductor bus bar30also from the connection surface38aof the coupling part38. The state where the insertion portion54aof the temperature sensor50is in contact with the connection surface38aincludes a state where the insertion portion54ais close to, i.e., substantially in contact with, the connection surface38a.

In this embodiment, (a) the neutral conductor bus bar30has the bus bar main body32that is extended into an elongated shape in the circumferential direction of the stator core20, and the connection terminals34that connect the bus bar main body32and the coils16to each other; (b) the first U-shaped part40that is bent so as to form the pair of opposite surfaces40a,40bfacing each other, and the second U-shaped part42that is bent so as to form the pair of opposite surfaces42a,42bfacing each other are provided side by side in the bus bar main body32; (c) the one opposite surface40aof the pair of opposite surfaces40a,40band the one opposite surface42aof the pair of opposite surfaces42a,42bare located in the same plane, and the other opposite surface40bof the pair of opposite surfaces40a,40band the other opposite surface42bof the pair of opposite surfaces42a,42bare located in the same plane; and (d) the temperature sensor50is retained by being inserted through the gap40gbetween the pair of opposite surfaces40a,40band the gap42gbetween the pair of opposite surfaces42a,42b. Thus, the temperature sensor50is retained by being inserted through the gaps40g,42gbetween the pair of opposite surfaces40a,40band the pair of opposite surfaces42a,42b, i.e., more than one gap. Compared with when the temperature sensor50is retained by being inserted through a single gap, the heat receiving area of the temperature sensor50that receives heat from the neutral conductor bus bar30can be increased to maintain the measurement accuracy of the temperature in the neutral conductor bus bar30. For example, having a large heat receiving area, the temperature sensor50can achieve high responsiveness to changes in the temperature of the neutral conductor bus bar30in temperature measurement. Moreover, having a large heat receiving area, the temperature sensor50is likely to maintain robustness in measurement accuracy even when the mounting position of the temperature sensor50deviates to some extent in the insertion direction while the temperature sensor50is mounted so as to be retained by being inserted through the gap40gbetween the pair of opposite surfaces40a,40band the gap42gbetween the pair of opposite surfaces42a,42bin the bus bar main body32.

In this embodiment, (a) the bus bar main body32is extended into an elongated shape in the circumferential direction of the stator core20, and (b) the first U-shaped part40and the second U-shaped part42are extended toward the outer circumferential side in the radial direction of the stator core20and then bent toward the inner circumferential side in the radial direction. The gap40gbetween the pair of opposite surfaces40a,40bformed by the first U-shaped part40and the gap42gbetween the pair of opposite surfaces42a,42bformed by the second U-shaped part42both open in the circumferential direction of the stator core20. This allows the temperature sensor50to be inserted along the circumferential direction of the stator core20in which these gaps40g,42gopen, which can increase the efficiency with which the temperature sensor50is mounted to the neutral conductor bus bar30.

In this embodiment, the first U-shaped part40and the second U-shaped part42are each bent into a U-shape in a plane including the axis CL. Surfaces through which the temperature sensor50can receive heat from the bus bar30include, other than the pair of opposite surfaces40a,40band the pair of opposite surfaces42a,42b, the inner circumferential surfaces40c,42cof the first U-shaped part40and the second U-shaped part42bent into a U-shape. Thus, the temperature sensor50can receive more heat from the neutral conductor bus bar30and maintain the measurement accuracy of the temperature in the neutral conductor bus bar30.

In this embodiment, (a) the thickness direction of the bus bar main body32is a direction parallel to the axis CL of the stator core20, and (b) the connection terminals34have a structure of being extended from the bus bar main body32toward the inner circumferential side in the radial direction of the stator core20and then bent in a direction parallel to the axis CL. The connection terminals34have a structure of being extended from the bus bar main body32toward the inner circumferential side in the radial direction of the stator core20and then bent only at one part in a direction parallel to the axis CL of the stator core20. Thus, the distance between the bus bar main body32and the connection terminal34in the radial direction can be reduced to keep the size of the neutral conductor bus bar30down.

In this embodiment, (a) the coupling part38that is bent into a U-shape and couples the first U-shaped part40and the second U-shaped part42to each other is formed between the first U-shaped part40and the second U-shaped part42; (b) the coupling part38has the connection surface38athat is located in the same plane as those opposite surfaces40b,42bof the pair of opposite surfaces40a,40band the pair of opposite surfaces42a,42bthat are located on the side of the coupling part38; and (c) the temperature sensor50is in contact with the connection surface38a. Surfaces through which the temperature sensor50can receive heat from the neutral conductor bus bar30include, other than the pair of opposite surfaces40a,40band the pair of opposite surfaces42a,42b, the connection surface38aof the coupling part38. Thus, the temperature sensor50can receive more heat from the neutral conductor bus bar30and maintain the measurement accuracy of the temperature in the neutral conductor bus bar30.

In this embodiment, the area of the cross-section of each of the first U-shaped part40, the second U-shaped part42, and the coupling part38cut along the width direction is equal to the area of the cross-section of the bus bar main body32cut along the width direction. This allows a current to flow through the neutral conductor bus bar30at the same current density in the first U-shaped part40, the second U-shaped part42, and the coupling part38and in the bus bar main body32. As a result, the neutral conductor bus bar30is likely to generate an equal amount of heat at parts in the longitudinal direction, including the first U-shaped part40, the second U-shaped part42, and the coupling part38, which helps maintain the measurement accuracy of the temperature in the neutral conductor bus bar30.

In this embodiment, (a) the coils16are Y-connected three-phase coils, and (b) the bus bar main body32is a neutral conductor of the coils16. Heat generated in each of the coils16of the Y-connected three-phase coils is conducted to the neutral conductor bus bar30from the one end of the coil16. Therefore, the temperature sensor50retained by the neutral conductor bus bar30can accurately measure the temperature of the coils16wound around the stator core20.

While the embodiment of the present disclosure has been described in detail above based on the drawings, the present disclosure can be implemented also with other aspects.

In the above-described embodiment, the first U-shaped part40and the second U-shaped part42are extended toward the outer circumferential side in the radial direction of the stator core20and then bent into a U-shape toward the inner circumferential side in the radial direction. However, an applicable embodiment of the present disclosure is not limited to this aspect. For example, the first U-shaped part40and the second U-shaped part42may be extended toward the one side in a direction parallel to the axis CL of the stator core20and then bent into a U-shape toward the other side in the direction parallel to the axis CL. In the case of this aspect, it is preferable that the bus bar main body32have an elongated shape extended in the circumferential direction of the stator core20and that the thickness direction of the bus bar main body32lie along the radial direction. The pair of opposite surfaces40a,40band the pair of opposite surfaces42a,42bof the first U-shaped part40and the second U-shaped part42need not entirely face each other in the width direction as in the above-described embodiment, and should face each other at least partially in the width direction.

In the above-described embodiment, the first U-shaped part40corresponding to the first bent part and the second U-shaped part42corresponding to the second bent part are each bent into a U-shape, but an applicable embodiment of the present disclosure is not limited to this aspect. For example, each of the first bent part and the second bent part may be a part that is bent into a V-shape and has a pair of opposite surfaces facing each other across a gap.

In the above-described embodiment, the thickness direction of the bus bar main body32is a direction parallel to the axis CL of the stator core20, and the connection terminals34have a structure of being extended from the bus bar main body32toward the inner circumferential side in the radial direction of the stator core20and then bent in a direction parallel to the axis CL, but an applicable embodiment of the present disclosure is not limited to this aspect. For example, the thickness direction of the bus bar main body32may lie in the radial direction of the stator core20. In the case of this configuration, for example, the connection terminals34have a structure of being bent from the bus bar main body32toward the inner circumferential side in the radial direction of the stator core20and further bent in a direction parallel to the axis CL.

In the above-described embodiment, the temperature sensor50measures the temperature of the neutral conductor bus bar30, but an applicable embodiment of the present disclosure is not limited to this aspect. For example, the bus bar of which the temperature is measured by the temperature sensor50may be one of the terminal bus bars18U,18V,18W connected to the other ends of the three-phase coils16. Heat generated in the three-phase coils16is conducted from the other ends of the coils also to the terminal bus bars18U,18V,18W connected to the respective coils. Therefore, the temperature sensor50that is retained by being inserted through the gap of the bent part36provided in one of the terminal bus bars18U,18V,18W can measure the temperature of the coils16wound around the stator core20.

In the above-described embodiment, the bus bar main body32is extended into an elongated shape in the circumferential direction of the stator core20, but an applicable embodiment of the present disclosure is not limited to this aspect. For example, when the bus bar of which the temperature is measured by the temperature sensor50is one of the terminal bus bars18U,18V,18W, the bus bar main body32need not necessarily extend in the circumferential direction of the stator core20and may instead extend in the radial direction as shown inFIG.2.

In the above-described embodiment, the bent part36is provided between the connection terminal34V and the connection terminal34W, but an applicable embodiment of the present disclosure is not limited to this aspect. For example, the bent part36may be provided between the connection terminal34U and the connection terminal34V, or the bent part36may be provided at the end of the bus bar main body32on the one side or the other side in the circumferential direction.

In the above-described embodiment, the coils16wound around the stator core20have a three-phase, three-coil configuration, but an applicable embodiment of the present disclosure is not limited to this aspect. For example, the coils16wound around the stator core20may have other configuration, such as a three-phase, six-coil configuration. For example, in the case of a three-phase, six-coil configuration, each of the connection terminals34U,34V,34W is provided at two locations in the corresponding phase in the neutral conductor bus bar30. One end of each of the coils in the three-phase six-coil configuration is connected to the neutral conductor bus bar30. The terminal bus bars18U,18V,18W are extended into an elongated shape in the circumferential direction of the stator core20, and the other ends of the respective coils in the three-phase six-coil configuration are connected to the terminal bus bars18U,18V,18W.

What has been described above is merely an embodiment of the present disclosure, and the present disclosure can be implemented with various changes and improvements made to its aspects based on the knowledge of those skilled in the art within the scope of the gist of the present disclosure.