Busbar apparatus, motor, and method of manufacturing busbar apparatus

A busbar apparatus includes a busbar to be connected to an external device, and a holder to hold the busbar and made of an insulating material. The busbar includes a terminal portion to be connected to the external device, an intermediate portion continuous with the terminal portion, and a connection portion continuous with the intermediate portion. The intermediate portion includes an edge portion including portions extending along a first axis. The terminal portion extends from the edge portion. The connection portion extends from the edge portion away from the terminal portion. The terminal portion has a thickness direction extending along a second axis not parallel to the first axis. The connection portion has a thickness direction not parallel to the second axis.

CROSS REFERENCE TO RELATED APPLICATION

The present invention claims priority under 35 U.S.C. § 119 to Japanese Application No. 2019-059608 filed on Mar. 27, 2019, the entire contents of which are hereby incorporated herein by reference.

1. FIELD OF THE INVENTION

The present disclosure relates to a busbar apparatus, a motor, and a method of manufacturing the busbar apparatus.

A busbar apparatus which is arranged to connect coil wires drawn out from a stator to a connection target, such as, for example, an external device, is known.

The known busbar apparatus includes a plurality of busbars, and a busbar holder arranged to hold the busbars. The busbar holder is fitted to the stator. Each busbar includes a terminal portion connected to the connection target, such as, for example, the external device, and a connection portion connected to one of the coil wires drawn out from the stator. Such a busbar is manufactured, for example, by being stamped out of an electrically conductive, metal plate material through press working.

In the busbar apparatus as described above, the busbars tend to have a complicated shape to avoid electrical continuity therebetween, which leads to a large amount of scrap.

SUMMARY

A busbar apparatus according to an example embodiment of the present disclosure includes a busbar to be connected to an external device, and a holder to hold the busbar and made of an insulating material. The busbar includes a terminal portion to be connected to the external device, an intermediate portion continuous with the terminal portion, and a connection portion continuous with the intermediate portion. The intermediate portion includes an edge portion including portions extending along a first axis. The terminal portion extends from the edge portion. The connection portion extends from the edge portion away from the terminal portion. The terminal portion has a thickness direction extending along a second axis not parallel to the first axis. The connection portion has a thickness direction not parallel to the second axis.

A motor according to an example embodiment of the present disclosure includes a stator including a coil, a rotor supported to be capable of rotating relative to the stator, and the above-described busbar apparatus. The busbar is capable of connecting the external device and a lead wire drawn out from the coil of the stator to each other.

According to an example embodiment of the present disclosure, there is provided a method of manufacturing a busbar apparatus including a busbar to connect an external device and a lead wire drawn out from a coil of a stator to each other, and a holder to hold the busbar and made of an insulating material. The busbar includes a terminal portion to be connected to the external device, an intermediate portion continuous with the terminal portion, and a connection portion continuous with the intermediate portion. The intermediate portion includes an edge portion including portions extending along a first axis. The terminal portion extends from the edge portion. The connection portion extends from the edge portion away from the terminal portion. The terminal portion has a thickness direction extending along a second axis not parallel to the first axis. The connection portion has a thickness direction not parallel to the second axis. The method includes the steps of a) stamping a material from which the terminal portion, the intermediate portion, and the connection portion are to be made out of an electrically conductive plate material; and b) bending the material to define the busbar.

DETAILED DESCRIPTION

Hereinafter, busbar apparatuses and motors according to example embodiments of the present disclosure will be described with reference to the accompanying drawings. In the following description, a direction parallel to a central axis J (seeFIG. 1) is simply referred to by the term “axial direction”, “axial”, or “axially”, radial directions centered on the central axis J are simply referred to by the term “radial direction”, “radial”, or “radially”, and a circumferential direction centered on the central axis J, i.e., a circumferential direction about the central axis J, is simply referred to by the term “circumferential direction”, “circumferential”, or “circumferentially”. It should be noted that the above definition of each of the above directions is made simply for the sake of convenience in description, and is not meant to restrict the posture of a busbar apparatus or a motor when in use or circulation. In addition, a radial direction, a circumferential direction, and an axial direction correspond to a direction of a first axis, a direction of a second axis, and a direction of a third axis, respectively. In the accompanying drawings, a first axial side, i.e., a first side in the axial direction, a second axial side, i.e., a second side in the axial direction, an inner side in a radial direction, an outer side in the radial direction, a first circumferential side, i.e., a first side in the circumferential direction, and a second circumferential side, i.e., a second side in the circumferential direction, are denoted as “+J”, “−J”, “+R”, “−R”, “+C”, and “−C”, respectively.

FIG. 1is an exploded perspective view of a motor1according to the present example embodiment. Referring toFIG. 1, the motor1includes a cylindrical housing2, a stator3fixed to an inner circumferential surface of the housing2, and a rotor4housed inside of the stator3, and supported to be capable of rotating about an axis relative to the stator3. The rotor4includes a shaft5arranged to extend along the central axis J.

Referring toFIG. 1, the housing2is arranged to open to the first axial side. A busbar apparatus10is fitted in an opening portion of the housing2to close the opening portion. That is, the motor1includes the busbar apparatus10. In the present example embodiment, the busbar apparatus10is arranged on an upper side of a bearing holder. The motor1, which includes the busbar apparatus10, is, for example, attached to a power steering apparatus to form an electric power steering apparatus. The electric power steering apparatus is arranged to provide assistance in a steering operation using a driving force of the motor1.

FIG. 2is a perspective view of the busbar apparatus according to the present example embodiment as viewed from the first axial side. Referring toFIG. 2, the busbar apparatus10includes busbars20, electrically conductive members30, and a holder40arranged to hold the busbars20and the electrically conductive members30.

The holder40is made of an insulating material, such as, for example, polybutylene terephthalate (PBT). The holder40includes a first annular portion41, a second annular portion42, three first joining portions43, and three second joining portions44. The holder40corresponds to a holding member.

The first annular portion41is a plate portion in the shape of a circular ring and centered on the central axis J. Principal surfaces of the first annular portion41are arranged to extend perpendicularly to the central axis J. The first annular portion41is arranged to have a constant plate thickness. The principal surface of the first annular portion41on the first axial side corresponds to a flat portion.

FIG. 3is a side view of the busbar apparatus according to the present example embodiment as viewed from the outer side in a radial direction. Referring toFIGS. 2 and 3, the second annular portion42is tubular, and is centered on the central axis J. The second annular portion42is located inside of the first annular portion41. The second annular portion42is arranged to have an axial dimension greater than the plate thickness of the first annular portion41. The second annular portion42is arranged to project to both the first axial side and the second axial side relative to the first annular portion41. In the present example embodiment, the second annular portion42is arranged to have a circular internal shape. A portion of the second annular portion42which lies on the first axial side of an axial middle portion of the second annular portion42is arranged to have a regular hexagonal external shape. Meanwhile, a portion of the second annular portion42which lies on the second axial side of the axial middle portion of the second annular portion42is arranged to have a circular external shape.

Referring toFIG. 2, each of the three first joining portions43is arranged to extend perpendicularly to the central axis J. Each of the three first joining portions43is connected to two different portions of the first annular portion41at longitudinal end portions thereof without crossing any other first joining portion43. In addition, each of the three first joining portions43is connected to the second annular portion42at a longitudinal middle portion thereof. Principal surfaces of each of the three first joining portions43are arranged to extend perpendicularly to the central axis J. Each first joining portion43is arranged to have a plate thickness greater than the plate thickness of the first annular portion41. The plate thickness of the first joining portion43is smaller than the plate thickness of the second annular portion42.

Each of the three second joining portions44is arranged to extend perpendicularly to the central axis J. Each of the three second joining portions44is connected to two different portions of the first annular portion41at longitudinal end portions thereof without crossing any other second joining portion44. In addition, each of the three second joining portions44is connected to the second annular portion42at a longitudinal middle portion thereof. Each second joining portion44is arranged to cross two of the three first joining portions43. Principal surfaces of each of the three second joining portions44are arranged to extend perpendicularly to the central axis J. Each second joining portion44is arranged to have a plate thickness greater than the plate thickness of each first joining portion43.

FIG. 4is a perspective view of the busbar apparatus according to the present example embodiment as viewed from the second axial side. Referring toFIGS. 2 and 4, the principal surface of each of the three first joining portions43and the three second joining portions44on the second axial side is arranged at the same axial position as that of the principal surface of the first annular portion41on the second axial side. In other words, the principal surface of each of the three first joining portions43and the three second joining portions44on the side closer to the stator3and the principal surface of the first annular portion41on the side closer to the stator3are arranged at the same axial position. Accordingly, the principal surface of each of the three first joining portions43on the first axial side projects to the first axial side relative to the principal surface of the first annular portion41on the first axial side. In other words, the principal surface of each of the three first joining portions43on the side opposite to the stator projects to the first axial side relative to the principal surface of the first annular portion41on the side opposite to the stator3. In addition, the principal surface of each of the three second joining portions44on the first axial side projects to the first axial side relative to the principal surface of each first joining portion43on the first axial side.

As a result of crossing of the three first joining portions43and the three second joining portions44, the holder40includes twelve through holes45each of which is arranged to pass therethrough in the axial direction between the first annular portion41and the second annular portion42. The twelve through holes45are arranged in the circumferential direction.

Referring toFIG. 2, the first annular portion41has three pairs of opposed portions46arranged to project from the principal surface thereof on the first axial side, which corresponds to the flat portion. Each pair of opposed portions46is made up of a pair of support portions47aand47barranged opposite to each other in the circumferential direction about the central axis J. Here, the support portion on the first circumferential side is defined as a first support portion47a, while the support portion on the second circumferential side is defined as a second support portion47b. The first support portion47ais displaced radially outward relative to the second support portion47b. The holder40includes the three pairs of opposed portions46. The three pairs of opposed portions46are arranged at equal angular intervals in the circumferential direction about the central axis J. To be more precise, the three first support portions47aare arranged at equal angular intervals in the circumferential direction about the central axis J. The three second support portions47bare arranged at equal angular intervals in the circumferential direction about the central axis J.

Surfaces of the first support portion47aand the second support portion47bwhich are opposed to each other are rectangular principal surfaces arranged to extend along the axial direction. The principal surfaces of the first support portion47aand the second support portion47bare arranged to be parallel to each other.

Referring toFIG. 2, the electrically conductive members30include three first electrically conductive members31and three second electrically conductive members32. Each of the first electrically conductive members31and the second electrically conductive members32corresponds to an intermediate electrically conductive member.

Each of the three first electrically conductive members31is a plate member arranged to have a plate width and a plate thickness smaller than those of the first joining portion43. Each of the three first electrically conductive members31is arranged to extend along the corresponding first joining portion43, and is insert-molded in the corresponding first joining portion43. Each of the three first electrically conductive members31includes a first joint end portion31aand first and second coil joint end portions31band31c.

The first joint end portion31ais defined at one longitudinal end portion of the first electrically conductive member31. The first joint end portion31ais in the shape of a disk, and is arranged to have a diameter greater than a plate width of a remaining portion of the first electrically conductive member31. The first joint end portion31ais exposed outside of an end portion of the corresponding first joining portion43. A surface of the first joint end portion31aon the first axial side is arranged to be smoothly continuous with the surface of the first annular portion41on the first axial side.

The first coil joint end portion31bis defined at a longitudinal end portion of the first electrically conductive member31on the side opposite to the first joint end portion31a. A distal end portion of the first coil joint end portion31bis arranged to divide into two parts spaced from each other in a radial direction. The first coil joint end portion31bis arranged to project to the first circumferential side from the corresponding first joining portion43. That is, the first coil joint end portion31bis arranged to project to one of the through holes45.

The second coil joint end portion31cis a portion arranged to project to the first circumferential side from a longitudinal middle portion of the first electrically conductive member31, i.e., from a position between the first joint end portion31aand the first coil joint end portion31b. A distal end portion of the second coil joint end portion31cis arranged to divide into two parts spaced from each other in a radial direction. The second coil joint end portion31cis arranged to project to the first circumferential side from the corresponding first joining portion43. That is, the second coil joint end portion31cis arranged to project to one of the through holes45different from the through hole45to which the first coil joint end portion31bprojects.

Each of the three second electrically conductive members32is a plate member arranged to have a plate width and a plate thickness equivalent to those of the first electrically conductive member31. Accordingly, the plate width and the plate thickness of each of the three second electrically conductive members32are smaller than those of the second joining portion44. Each of the three second electrically conductive members32is arranged to extend along the corresponding second joining portion44, and is insert-molded in the corresponding second joining portion44. Each second electrically conductive member32is located more on the first axial side in the axial direction than each first electrically conductive member31by a distance equal to the plate thickness of the first electrically conductive member31. Each of the three second electrically conductive members32includes a second joint end portion32aand first and second coil joint end portions32band32c.

The second joint end portion32ais defined at one longitudinal end portion of the second electrically conductive member32. The second joint end portion32ais in the shape of a disk, and is arranged to have a diameter greater than a plate width of a remaining portion of the second electrically conductive member32. The second joint end portion32ais exposed outside of an end portion of the corresponding second joining portion44. A surface of the second joint end portion32aon the first axial side is arranged to be smoothly continuous with the surface of the first annular portion41on the first axial side.

The first coil joint end portion32bis defined at a longitudinal end portion of the second electrically conductive member32on the side opposite to the second joint end portion32a. A distal end portion of the first coil joint end portion32bis arranged to divide into two parts spaced from each other in a radial direction. The first coil joint end portion32bis arranged to project to the first circumferential side from the corresponding second joining portion44. That is, the first coil joint end portion32bis arranged to project to one of the through holes45.

The second coil joint end portion32cis a portion arranged to project to the first circumferential side from a longitudinal middle portion of the second electrically conductive member32, i.e., from a position between the second joint end portion32aand the first coil joint end portion32b. A distal end portion of the second coil joint end portion32cis arranged to divide into two parts spaced from each other in a radial direction. The second coil joint end portion32cis arranged to project to the first circumferential side from the corresponding second joining portion44. That is, the second coil joint end portion32cis arranged to project to one of the through holes45different from the through hole45to which the first coil joint end portion32bprojects.

The first joint end portions31aare arranged at equal angular intervals in the circumferential direction about the central axis J, and the second joint end portions32aare arranged at equal angular intervals in the circumferential direction about the central axis J. The first joint end portion31aand the second joint end portion32awhich make a pair have the opposed portions46therebetween in the circumferential direction. In more detail, the first joint end portion31aand the second joint end portion32awhich make a pair are arranged along a tangent to a circle centered on the central axis J at the corresponding opposed portions46. A distance between the first support portion47aand the first joint end portion31ais equal to a distance between the second support portion47band the second joint end portion32a.

The distance from the central axis J to each of the coil joint end portions31b,31c,32band32cis equal. In addition, the coil joint end portions31b,31c,32b, and32care arranged at equal angular intervals in the circumferential direction about the central axis J. Referring toFIG. 1, each of the coil joint end portions31b,31c,32b, and32cis joined to one of end portions of coils6drawn out from the stator3.

Next, the busbars20will now be described below.

Referring toFIG. 2, the busbar apparatus10includes three of the busbars20. While the three busbars20are arranged at equal angular intervals in the circumferential direction about the central axis J, each busbar20has the same structure, and therefore, the busbars20will be described without being differentiated from each other.

FIG. 5is a perspective view of the busbar according to the present example embodiment. Referring toFIG. 5, the busbar20includes a terminal portion21, a pair of intermediate portions22aand22b, and a pair of connection portions23aand23b.

Referring toFIGS. 2 and 5, each of which illustrates the busbar(s)20as viewed from the first axial side, the intermediate portion22aincludes a plate-shaped first intermediate portion221aarranged to extend radially inward from a center of the corresponding opposed portions46, a plate-shaped second intermediate portion222aarranged to extend to the first circumferential side from a radially inner, distal end portion of the first intermediate portion221a, and a plate-shaped third intermediate portion223aarranged to extend radially outward from a distal end portion of the second intermediate portion222aon the first circumferential side. The intermediate portion22bincludes a plate-shaped first intermediate portion221barranged to extend radially outward from the center of the corresponding opposed portions46, a plate-shaped second intermediate portion222barranged to extend to the second circumferential side from a radially outer, distal end portion of the first intermediate portion221b, and a plate-shaped third intermediate portion223barranged to extend radially inward from a distal end portion of the second intermediate portion222bon the second circumferential side. Principal surfaces of the first intermediate portion221aof the intermediate portion22aare arranged to be smoothly continuous with principal surfaces of the first intermediate portion221bof the intermediate portion22b. The intermediate portion22aand the intermediate portion22bare arranged at the same axial position.

The first intermediate portions221aand221bare arranged between the corresponding opposed portions46, i.e., the corresponding first support portion47aand the corresponding second support portion47b. The first intermediate portion221aand the corresponding first support portion47aare arranged circumferentially opposite to each other. The first intermediate portion221band the corresponding second support portion47bare arranged circumferentially opposite to each other. The radially inner, distal end portion of the first intermediate portion221ais located radially inward of a radially inner edge portion of the corresponding first support portion47a. The radially outer, distal end portion of the first intermediate portion221bis located radially outward of a radially outer edge portion of the corresponding first support portion47a. Each of the principal surfaces of the first intermediate portions221aand221bis arranged to be perpendicular to the circumferential direction. An edge portion of each of the first intermediate portions221aand221bon the second axial side is arranged to be in contact with the holder40. To be more precise, the edge portion of each of the first intermediate portions221aand221bon the second axial side is arranged to be in contact with the surface of the first annular portion41on the first axial side.

The second intermediate portion222ais located radially inside of the corresponding first support portion47a. The second intermediate portion222bis located radially outside of the corresponding second support portion47b. The second intermediate portions222aand222bare arranged to have the corresponding opposed portions46therebetween in a radial direction. Each of principal surfaces of the second intermediate portions222aand222bis arranged to be perpendicular to the radial direction.

The third intermediate portion223ais located on the first circumferential side of the corresponding first support portion47a. The third intermediate portion223bis located on the second circumferential side of the corresponding second support portion47b. The third intermediate portions223aand223bare arranged to have the corresponding opposed portions46therebetween in the circumferential direction. In addition, the first intermediate portion221aand the third intermediate portion223aare arranged to have the corresponding first support portion47atherebetween in the circumferential direction. Further, the first intermediate portion221band the third intermediate portion223bare arranged to have the corresponding second support portion47btherebetween in the circumferential direction. Each of principal surfaces of the third intermediate portions223aand223bis arranged to be perpendicular to the circumferential direction. Each of the principal surfaces of the third intermediate portions223aand223bis arranged to be parallel to each of the principal surfaces of the first intermediate portions221aand221b. The pair of intermediate portions22aand22bas a whole forms the shape of the letter “S” when viewed along the axial direction. The pair of intermediate portions22aand22bis arranged to have a constant plate width, i.e., a constant axial dimension. The pair of intermediate portions22aand22bis arranged to have point symmetry with respect to the terminal portion21. An edge portion of each of the intermediate portions22aand22bon the second axial side is arranged to be in contact with the principal surface of the first annular portion41on the first axial side. That is, the intermediate portions22aand22bare arranged along the principal surface, which corresponds to the flat portion, of the first annular portion41on the first axial side. Here, an edge portion of the intermediate portions22aand22bon the first axial side is defined as an edge portion25. The edge portion25extends over all of the first intermediate portions221aand221b, the second intermediate portions222aand222b, and the third intermediate portions223aand223b. That is, the edge portion25refers to surfaces of the intermediate portions22aand22bwhich extend perpendicularly to the axial direction. The edge portion25is a junction between the terminal portion21, which will be described in detail below, and each of the connection portions23aand23b.

The terminal portion21is a plate-shaped portion arranged to extend to the first axial side from edge portions of the first intermediate portions221aand221bon the first axial side, i.e., from a portion of the edge portion25. The terminal portion21includes a first terminal portion21aarranged to extend from the edge portion25to the first axial side, and a second terminal portion21barranged to extend to the first axial side from a distal end portion of the first terminal portion21a. The terminal portion21is arranged between the corresponding opposed portions46. Each of principal surfaces of the first terminal portion21aand the second terminal portion21bis arranged to be perpendicular to the circumferential direction. A thickness direction of the terminal portion21is the circumferential direction. The principal surfaces of the first terminal portion21aand the second terminal portion21bare arranged to be smoothly continuous with the principal surfaces of the first intermediate portions221aand221b.

The second terminal portion21bis displaced radially outward relative to the first terminal portion21a. The extent of the radial displacement between the first terminal portion21aand the second terminal portion21bis equal to a plate thickness of each of the intermediate portions22aand22b. As a result, the second terminal portion21band the second intermediate portion222boverlap with each other when viewed in the axial direction. The radially outward displacement of the second terminal portion21bcorrespondingly increases a spare space around the central axis J. A distal end portion of the second terminal portion21bis connected to an external device (not shown). The external device is, for example, a control circuit board of the electric power steering apparatus. The external device may alternatively be a control circuit board having a power supply circuit or a power conversion device. That is, the terminal portion21is connected to a control circuit board. Power is supplied from the external device to drive the motor1.

The plate width, i.e., the radial dimension, of the terminal portion21is preferably equal to or greater than twice the plate width of each of the intermediate portions22aand22b. The terminal portion21is arranged to project to the first axial side relative to an end portion of each of the corresponding opposed portions46on the first axial side.

The connection portion23aincludes a first connection portion231aarranged to extend to the first circumferential side from an edge portion of the third intermediate portion223aon the first axial side, i.e., from a portion of the edge portion25, a second connection portion232aarranged to extend to the second axial side from a distal end portion of the first connection portion231a, and a third connection portion233aarranged to extend to the first circumferential side from a distal end portion of the second connection portion232a. The connection portion23bincludes a first connection portion231barranged to extend to the second circumferential side from an edge portion of the third intermediate portion223bon the first axial side, i.e., from a portion of the edge portion25, a second connection portion232barranged to extend to the second axial side from a distal end portion of the first connection portion231b, and a third connection portion233barranged to extend to the second circumferential side from a distal end portion of the second connection portion232b.

Each of principal surfaces of the first connection portions231aand231band principal surfaces of the third connection portions233aand233bis arranged to be perpendicular to the axial direction. A thickness direction of each of the first connection portions231aand231band the third connection portions233aand233bis the axial direction. Each of principal surfaces of the second connection portions232aand232bis arranged to be perpendicular to the circumferential direction. Each of the principal surfaces of the second connection portions232aand232bis arranged to be parallel to each of the principal surfaces of the terminal portion21, the first intermediate portions221aand221b, and the third intermediate portions223aand223b. A thickness direction of each of the second connection portions232aand232bis the circumferential direction.

Distal end portions of the third connection portions233aand233bare disk-shaped busbar joint end portions234aand234b, respectively, each of which is arranged to have a diameter greater than a plate width of a remaining portion of each of the connection portions23aand23b. The diameter of each of the busbar joint end portions234aand234bis arranged to be smaller than the diameter of each of the first and second joint end portions31aand32a.

The second connection portion232bis arranged to have an axial dimension greater than an axial dimension of the second connection portion232aby the plate thickness of each second electrically conductive member32. A surface of the busbar joint end portion234aon the second axial side is arranged to overlap with the surface of the corresponding first joint end portion31aon the first axial side. A surface of the busbar joint end portion234bon the second axial side is arranged to overlap with the surface of the corresponding second joint end portion32aon the first axial side. The busbar joint end portion234aand the corresponding first joint end portion31aare joined to each other through, for example, projection welding. The busbar joint end portion234band the corresponding second joint end portion32aare joined to each other through, for example, projection welding. Each of the connection portions23aand23bis arranged to have a plate width equal to the plate width of each of the intermediate portions22aand22b.

If a portion of the busbar20is described as being arranged in a vertical orientation, it means that this portion is arranged to have principal surfaces thereof parallel to the axial direction. If a portion of the busbar20is described as being arranged in a horizontal orientation, it means that this portion is arranged to have principal surfaces thereof not parallel to the axial direction, particularly, perpendicular to the axial direction. In the present example embodiment, the busbar20is arranged such that each of the terminal portion21and the intermediate portions22aand22bis in the vertical orientation while each of the connection portions23aand23bis in the horizontal orientation.

Thus, in the busbar20, each of a boundary between the intermediate portion22aand the connection portion23aand a boundary between the intermediate portion22band the connection portion23bis bent. To be more precise, each of a boundary portion B between the third intermediate portion223aand the first connection portion231aand a boundary portion B between the third intermediate portion223band the first connection portion231bis bent. Further, each of a boundary portion B between the first connection portion231aand the second connection portion232a, a boundary portion B between the first connection portion231band the second connection portion232b, a boundary portion B between the second connection portion232aand the third connection portion233a, and a boundary portion B between the second connection portion232band the third connection portion233bis bent. In other words, each intermediate portion includes a first intermediate portion continuous with the terminal portion, and a second intermediate portion continuous with the connection portion, and further includes at least one bent boundary portion between the first intermediate portion and the second intermediate portion. A stress would be reduced at each boundary portion B through a deformation at the boundary portion B. Accordingly, even if an axial stress is applied to the busbar20, for example, when connection between the external device (not shown) and the terminal portion21is broken, a force exerted on each of the connection portions23aand23bis reduced. Therefore, a break in connection between the connection portions23aand23band the corresponding first electrically conductive member31and the corresponding second electrically conductive member32, respectively, does not easily occur.

In addition, each of a boundary portion B between the first intermediate portion221aand the second intermediate portion222a, a boundary portion B between the first intermediate portion221band the second intermediate portion222b, a boundary portion B between the second intermediate portion222aand the third intermediate portion223a, and a boundary portion B between the second intermediate portion222band the third intermediate portion223bis bent. Accordingly, even if a radial stress is applied to the busbar20, a force exerted on each of the connection portions23aand23bis reduced. Therefore, a break in the connection between the connection portions23aand23band the corresponding first electrically conductive member31and the corresponding second electrically conductive member32, respectively, does not easily occur. In other words, each of the intermediate portions22aand22bincludes the first intermediate portion221aor221b, which is continuous with the terminal portion21, and the third intermediate portion223aor223b, which is continuous with the connection portion23aor23b, and further includes the boundary portions B between the first intermediate portion221aor221band the third intermediate portion223aor223b.

The busbar apparatus10, which includes the busbars20, is attached to the motor1used in the electric power steering apparatus. Heat is inputted to and released from components of the electric power steering apparatus, such as, for example, the control circuit board and the motor1, through supply of electric current or an operation of the motor1or due to an external environment. That is, the components of the electric power steering apparatus may experience thermal expansion and thermal contraction due to the input and release of heat. However, different metal materials are used to make the components of the electric power steering apparatus. In other words, components of the electric power steering apparatus have different coefficients of linear expansion, and are therefore different in extent of deformation and displacement. Accordingly, a deformation and a displacement of each component of the electric power steering apparatus may be inputted also to the busbars20, which connect the control circuit board and the motor1to each other. That is, the busbars20may receive an external force. However, each busbar20includes the bent boundary portions B as described above, and therefore, a distal end portion of the terminal portion21thereof is capable of moving relative to each of the busbar joint end portions234aand234bin the axial, radial, and circumferential directions. Thus, the busbar20has a flexible structure, including the bent boundary portions B, and this contributes to reducing a stress applied to the control circuit board, to which the busbar20is connected.

The plate width of the terminal portion21is preferably equal to or greater than twice the plate width of each of the intermediate portions22aand22b. This contributes to reducing losses of electric current in the busbars20, the busbar apparatus10, and the motor1, and thus to reducing generation of heat.

Further, since each busbar20is arranged to extend in the circumferential direction, a relatively large space in which the electrically conductive members are arranged can be secured radially inside of the busbars20. In particular, since the direction in which each of the principal surfaces of the terminal portion21faces and the direction in which each of the connection portions23aand23bextends are the same, a reduction in the size of the busbar20as a whole can be achieved. In other words, each of the principal surfaces of the terminal portion21and each of the principal surfaces of the connection portions23aand23bare skew to each other, i.e., neither intersect each other nor are parallel to each other.

Next, a method of manufacturing the busbars20will now be described below.

FIG. 6is a plan view illustrating an arrangement of materials which are stamped out of an electrically conductive plate material to define busbars according to the present example embodiment, that is, an arrangement of materials from each of which the terminal portion, the intermediate portions, and the connection portions are to be made. Referring toFIG. 6, a step of stamping materials M1of the busbars20out of an electrically conductive, metal plate material P is first performed. In this stamping step, a plurality of materials M1are stamped out at a time. Notice that each terminal portion21extends in a vertical direction inFIG. 6. A plate width direction of the terminal portion21is a left-right direction inFIG. 6. Each of the intermediate portions22aand22bextends in the left-right direction inFIG. 6. A plate width direction of each of the intermediate portions22aand22bis the vertical direction inFIG. 6. Each of the connection portions23aand23bextends in the vertical direction inFIG. 6. A plate width direction of each of the connection portions23aand23bis the left-right direction inFIG. 6.

In more detail, the materials M1are stamped out with connecting portions L connecting the materials M1. That is, the plurality of busbars20are stamped out of the same plate material P. When the plurality of materials M1are stamped out, one of the materials M1has, between the terminal portion21and each of the connection portions23aand23bthereof, the connection portions23aand23bof other of the materials M1. In addition, the plurality of materials M1are stamped out of the metal plate material with the terminal portion21of one of the materials M1arranged between the connection portion23aof another one of the materials M1and the connection portion23bof yet another one of the materials M1. This is due to the U-shaped arrangement of the terminal portion21, the intermediate portion22a, and the connection portion23aof each of the materials M1stamped out of the plate material P as illustrated inFIG. 6. This is also due to the U-shaped arrangement of the terminal portion21, the intermediate portion22b, and the connection portion23bof the material M1. Further, this is also because the following dimensional relationships are satisfied. That is, in each material M1, a sum of a dimension of the terminal portion21measured in a longitudinal direction thereof (i.e., the vertical direction inFIG. 6) and a dimension of each of the intermediate portions22aand22bmeasured in the plate width direction thereof (i.e., the vertical direction inFIG. 6) is greater than a sum of a dimension of each of the connection portions23aand23bmeasured in a longitudinal direction thereof (i.e., the vertical direction inFIG. 6) and a dimension of each of the intermediate portions22aand22bmeasured in the plate width direction thereof (i.e., the vertical direction inFIG. 6). In addition, in each material M1, a dimension of an interspace between the terminal portion21and each of the connection portions23aand23b(measured in the left-right direction inFIG. 6) is greater than the diameter of each of the busbar joint end portions234aand234bat the distal ends of the connection portions23aand23b, respectively.

Thus, in the material M1, the terminal portion21and the connection portions23aand23bare arranged in a radial direction, which is a direction in which each of the intermediate portions22aand22bextends. That is, the material M1is stamped out with at least the shape of the letter “U” formed by portions thereof. An intervening portion between the terminal portion21and each of the connection portions23aand23bof one of the materials M1may be a waste for the one material M1, but a portion of another one of the materials M1is made from the intervening portion, and therefore, the busbar apparatus10, a method of manufacturing which includes the above stamping step, and hence the motor1are able to achieve an improved material yield in manufacturing.

Next, a removing step of removing the connecting portions L from the plurality of materials M1stamped out of the metal plate material is performed. In this removing step, the connecting portions L are removed from the materials M1by stamping out the connecting portions L out of the materials M1or cutting off the connecting portions L, so that the materials M1are disconnected from one another. The terminal portion21is defined as a result of the removing step.

Since the plurality of materials M1are stamped out at a time as described above, the busbar apparatus10, the method of manufacturing which includes the above-described stamping step, and hence the motor1are able to achieve a reduction in the number of steps for manufacture thereof when compared to the case where the materials M1are stamped out one by one.

In addition, since the plurality of materials M1are stamped out with the connecting portions L connecting the materials M1, dimensional accuracy of the materials M1is high.

Next, a bending step of appropriately bending the material M1is performed as illustrated inFIG. 7.FIG. 7is a perspective view illustrating a process by which the material M1, from which the busbar is to be made, is formed into the busbar according to the present example embodiment.

To describe in detail, as illustrated inFIG. 7, the intermediate portions22aand22bof the material M1, each of which extends in a radial direction, are first bent at positions that have the terminal portion21therebetween. More specifically, the intermediate portion22ais bent toward the first circumferential side. In addition, the intermediate portion22b, which extends along the radial direction, is bent toward the second circumferential side. The first intermediate portions221aand221bare defined as a result of this bending step. In other words, a material M2is defined.

Next, in the material M2, the intermediate portion22ais bent radially outward, and the intermediate portion22bis bent radially inward. The second intermediate portions222aand222band the third intermediate portions223aand223bare defined as a result of this bending step. In other words, a material M3is defined.

Next, in the material M3, the connection portion23a, which is continuous with the edge portion of the third intermediate portion223aon the first axial side, i.e., a portion of the edge portion25, is bent toward the first circumferential side, and the connection portion23b, which is continuous with the edge portion of the third intermediate portion223bon the first axial side, i.e., a portion of the edge portion25, is bent toward the second circumferential side. In other words, a material M4is defined.

Next, in the material M4, each of the connection portions23aand23bis bent toward the second axial side. The first connection portions231aand231bare defined as a result of this bending step. In other words, a material M5is defined.

Next, in the material M5, the connection portion23ais bent toward the first circumferential side, and the connection portion23bis bent toward the second circumferential side. The second connection portions232aand232band the third connection portions233aand233bare defined as a result of this bending step. In other words, the busbar20is defined.

As described above, the busbars20are manufactured through a combination of the step of stamping out of the electrically conductive, metal plate material and the bending step. Thus, a process of manufacturing the busbars20is simplified.

Next, the method of manufacturing the busbar apparatus will now be described below. The electrically conductive members30are separately stamped out of an electrically conductive, metal plate material, and are thereafter unified with the holder40beforehand through an insert molding process.

Referring toFIG. 2, each busbar20is fitted to the holder40with the first intermediate portions221aand221band the terminal portion21thereof entering into a space between the corresponding opposed portions46. In this fitting step, the busbar joint end portion234aof the busbar20is arranged to overlap with the first joint end portion31aof the corresponding first electrically conductive member31when viewed in the axial direction, and the busbar joint end portion234bof the busbar20is arranged to overlap with the second joint end portion32aof the corresponding second electrically conductive member32when viewed in the axial direction.

Next, the busbar joint end portion234aand the first joint end portion31aare joined together through projection welding. Similarly, the busbar joint end portion234band the second joint end portion32aare joined together through projection welding.

As described above, the busbar apparatus10is manufactured through a combination of the fitting step of fitting the busbars20to the holder40, which is unified with the electrically conductive members30beforehand through the insert molding process, and a welding step of welding the overlapping metal portions together. Thus, a process of manufacturing the busbar apparatus10, and hence a process of manufacturing the motor1, are simplified. This leads to a reduced manufacturing load of the busbar apparatus10and hence a reduced manufacturing load of the motor1.

In addition, the overlapping of the busbar joint end portion234aand the first joint end portion31afacilitates the welding operation therefor. Similarly, the overlapping of the busbar joint end portion234band the second joint end portion32afacilitates the welding operation therefor.

Next, a method of manufacturing the motor1will now be described below. Referring toFIG. 1, the stator3and the rotor4are fitted to the housing2beforehand through a known process. Lead wires7drawn out from the coils6of the stator3are drawn out to the first axial side of the stator3. Each of the coils6is a power supply target to which power is supplied from the external device. The term “power supply target” refers to an end target to which power is to be supplied from the external device. The electrically conductive members30, i.e., the first electrically conductive members31and the second electrically conductive members32, are intermediate electrically conductive members connected to the power supply targets to which the power is supplied from the external device.

Referring toFIG. 1, the busbar apparatus10is moved from the first axial side to the second axial side toward the housing2with the stator3and the rotor4fitted therein, so that the busbar apparatus10is housed in the housing2. Next, each of the coil joint end portions31b,31c,32b, and32cis welded to a corresponding one of the lead wires7drawn out from the stator3to the first axial side. This welding is achieved, for example, through resistance welding. As a result of this welding, each of the coil joint end portions31b,31c,32b, and32cis unified with the corresponding lead wire7, so that the busbar apparatus10and the housing2are unified to manufacture the motor1.

As described above, the motor1is manufactured through a combination of a simple moving step of moving the busbar apparatus10in the axial direction toward the housing2previously unified with the stator3and the rotor4and a simple welding step of welding each of the lead wires7to a corresponding one of the coil joint end portions31b,31c,32b, and32c. Because the combination is made up of simple steps, a reduced manufacturing load of the motor1is achieved.

Next, modifications of the above-described example embodiment will now be described below.

In the above-described example embodiment, each of the intermediate portions may alternatively be a plate extending straight. In this case, the intermediate portion does not include a boundary between plates extending in different directions. Thus, the step of making the material M3from the material M2, i.e., a bending step, is eliminated from the above-described example embodiment. Accordingly, in the case where each of the intermediate portions of the busbar is a plate extending straight, a reduction in the number of steps for manufacturing the busbar is achieved due to the elimination of the above bending step.

In the above-described example embodiment, each of the connection portions may alternatively be a plate extending straight. In this case, the connection portion does not include a boundary between plates extending in different directions. Thus, the step of making the material M5from the material M4, i.e., a bending step, and the step of making the busbar20from the material M5, i.e., a bending step, are eliminated from the above-described example embodiment. Accordingly, in the case where each of the connection portions of the busbar is a plate extending straight, a reduction in the number of steps for manufacturing the busbar is achieved due to the elimination of the above bending steps.

In the above-described example embodiment, the first electrically conductive members31and the second electrically conductive members32may be omitted. In this case, the lead wires7extending from the coils6may be directly connected to the corresponding connection portions23aand23bof the busbars20. Thus, a reduction in the number of members of the busbar apparatus10, and hence a reduction in the number of members of the motor1, are achieved due to the omission of the first electrically conductive members31and the second electrically conductive members32. Accordingly, a reduction in weight of the busbar apparatus10, and hence a reduction in weight of the motor1, are achieved.

In the above-described example embodiment, each busbar may include only one intermediate portion and only one connection portion for one terminal portion.

FIG. 8is a perspective view of a busbar300according to a modification of the above-described example embodiment. Referring toFIG. 8, for example, the busbar300includes a terminal portion301arranged to extend in the axial direction, an intermediate portion302arranged to extend in a radial direction, and a connection portion303arranged to extend in the circumferential direction. A plate thickness direction of the terminal portion301is the radial direction. Each of principal surfaces of the terminal portion301is arranged to be perpendicular to the radial direction. A plate thickness direction of the intermediate portion302is the circumferential direction. Each of principal surfaces of the intermediate portion302is arranged to be perpendicular to the circumferential direction. A plate thickness direction of the connection portion303is the axial direction. Each of principal surfaces of the connection portion303is arranged to be perpendicular to the axial direction. The above arrangement is able to achieve advantageous effects similar to those of the above-described example embodiment.

FIG. 9is a perspective view of a busbar400according to a modification of the above-described example embodiment. Referring toFIG. 9, for example, the busbar400includes a terminal portion401arranged to extend in the axial direction, an intermediate portion402arranged to extend in a radial direction, and a connection portion403arranged to extend in the circumferential direction. A plate thickness direction of the terminal portion401is the circumferential direction. Each of principal surfaces of the terminal portion401is arranged to be perpendicular to the circumferential direction. A plate thickness direction of the intermediate portion402is the axial direction. Each of principal surfaces of the intermediate portion402is arranged to be perpendicular to the axial direction. A plate thickness direction of the connection portion403is the axial direction. Each of principal surfaces of the connection portion403is arranged to be perpendicular to the axial direction. The above arrangement is also able to achieve advantageous effects similar to those of the above-described example embodiment.

FIG. 10is a plan view illustrating an arrangement of materials M which are stamped out of an electrically conductive plate material P to define busbars according to a modification of the above-described example embodiment. In the case where busbars having the shape according to either of the above modifications are adopted, each of materials M from which the busbars are to be made is substantially in the shape of the letter “U” as illustrated inFIG. 10. In this case, the materials M can be stamped out such that a terminal portion and a connection portion of one of the materials M have a connection portion of another one of the materials M therebetween, which leads to an improved yield of the plate material P.

In the above-described example embodiment, the connecting portions L connecting one of the materials M and another one of the materials M may be omitted. In this case, two or more of the materials M may be stamped out of the plate material P at a time, or alternatively, the materials M may be stamped out of the plate material P one by one.

In the above-described example embodiment, positions at which the material M is bent and an order in which the material M is bent at the respective positions in the step of bending the material M to shape the busbar20are not limited to the positions and the order described in the above description of the above-described example embodiment. In the case where busbars arranged to have point symmetry with respect to the terminal portion are adopted as in the above-described example embodiment, it is preferable that the material M is bent from a center outward, i.e., from the terminal portion toward the intermediate portion and then from the intermediate portion toward the connection portion. This arrangement reduces the likelihood that a jig or the like which is used for bending will be caught between, for example, the terminal portion and the connection portion, and facilitates the bending step.

In the above-described example embodiment, each of the intermediate portions and the connection portions includes two bent boundary portions, but may alternatively include only one such boundary portion, three or more such boundary portions, or no such boundary portion. Note that the terminal portion may include one or more such boundary portions.

In each of the above-described example embodiment and the above-described modifications thereof, the shape of the distal end portion of each connection portion may be modified appropriately in accordance with the shape of a connection target thereof. In the case where the connection portion is directly connected to one of the lead wires drawn out from the coils, the distal end portion of the connection portion may be arranged to divide into two parts as is the case with each of the first and second coil joint end portions according to the above-described example embodiment.

In each of the above-described example embodiment and the above-described modifications thereof, the shape of the distal end portion of the terminal portion may be modified appropriately in accordance with the external device.

In the above-described example embodiment, the principal surfaces of the first intermediate portion and the principal surfaces of the third intermediate portion may not be parallel to one another.

In the above-described example embodiment, the principal surfaces of the first connection portion and the principal surfaces of the third connection portion may not be parallel to one another.

In the above-described example embodiment, the motor may not necessarily be applied to the electric power steering apparatus. The motor may alternatively be applied to any other desirable device, such as, for example, a motor used as a source of power to drive a vehicle or an oil pump.

In the above-described example embodiment, the busbar apparatus may not necessarily be applied to the motor. The busbar apparatus may alternatively be applied to an electronic control unit, such as, for example, an inverter module.

In each of the above-described example embodiment and the above-described modifications thereof, the direction in which each portion of each busbar extends and the directions in which the principal surfaces of each portion of each busbar extend may be appropriately modified. For example, the direction in which the terminal portion extends may not be parallel to the axial direction of the motor. Also, the thickness directions of the terminal portion, the intermediate portion, and the connection portion are perpendicular to one another in each of the above-described example embodiment and the above-described modifications thereof, but may not necessarily be perpendicular to one another, and may be simply not parallel to one another. It may be sufficient if the thickness direction of the distal end portion of the terminal portion and the thickness direction of the distal end portion of the connection portion are not parallel to each other.

Features of the above-described example embodiment and the above-described modifications thereof may be combined as long as no technical conflict arises.