Axial gap motor

Abstract

To improve assembling workability of a three-phase axial gap motor and reduce cost.SOLUTION: With an axial gap motor, a U-phase first coil 21 and a U-phase second coil 22 are integrally formed. A V-phase first coil 23 and a V-phase second coil 24 are integrally formed. A W-phase first coil 25 and a W-phase second coil 26 are integrally formed. The U-phase first coil 21, the V-phase first coil 23, and the W-phase first coil 25 are connected to a power supply circuit. The U-phase second coil 22, the V-phase second coil 24, and the W-phase second coil 26 are connected by a common bus bar 80.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present disclosure relates to an axial gap motor used for, for example, electric pumps and the like.

Background Art

[0002] Conventionally, as an electric pump, there has been known a pump provided with an axial gap motor in which a rotor and a stator are arranged to face each other with a predetermined gap in the rotation axis direction. For example, Patent Document 1 discloses a structure in which a plurality of stator cores arranged in the circumferential direction around a rotation shaft are integrally held by an electrically insulating resin material.

[0003] Further, Patent Documents 2 and 3 disclose a structure in which a plurality of stator core members each including a core, a coil wound around an outer periphery of the core, and a bobbin arranged between the core and the coil are integrally resin-molded in a state of being annularly arranged around a rotation shaft.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problem to be Solved by the Invention

[0005] Incidentally, Patent Document 3 describes a configuration in which multiple coils are arranged in a circumferential direction around the axis of rotation. For example, when there are six coils and a three-phase alternating current is being transmitted, one pair of coils will be provided for each of the U-phase, V-phase, and W-phase. In this case, busbars will be needed to connect the pair of U-phase coils, the pair of V-phase coils, and the pair of W-phase coils, resulting in at least three busbars being provided.

[0006] However, requiring three busbars increases the number of steps in the assembly process, worsening assembly efficiency and increasing costs due to the larger number of parts.

[0007] This disclosure has been made in view of the above, and its purpose is to improve the workability of assembling a three-phase axial gap motor and to reduce costs. [Means for solving the problem]

[0008] To achieve the above objective, a first aspect of this disclosure may be assumed to be a three-phase axial gap motor in which a stator having a U-phase first coil, a U-phase second coil, a V-phase first coil, a V-phase second coil, a W-phase first coil, and a W-phase second coil, and a magnet fixed to a rotating shaft are arranged with a predetermined gap in the direction of the rotating shaft. The U-phase first coil and the U-phase second coil are integrally formed from a first wire with one end of the U-phase first coil connected to one end of the U-phase second coil, the V-phase first coil and the V-phase second coil are integrally formed from a second wire with one end of the V-phase first coil connected to one end of the V-phase second coil, and the W-phase first coil and the W-phase second coil are integrally formed from a third wire with one end of the W-phase first coil connected to one end of the W-phase second coil. The other end of the first coil of the U phase, the other end of the first coil of the V phase, and the other end of the first coil of the W phase are connected to a power supply circuit. The other end of the second coil of the U phase, the other end of the second coil of the V phase, and the other end of the second coil of the W phase are connected to each other electrically by a common busbar, forming a star connection.

[0009] With this configuration, the first U-phase coil and the second U-phase coil are integrally formed by the first wire, eliminating the need for a dedicated busbar to connect the two coils. Similarly, dedicated busbars for connecting the first V-phase coil and the second V-phase coil, and for connecting the first W-phase coil and the second W-phase coil are also unnecessary. Therefore, only busbars connecting the other ends of the second U-phase coil, the other ends of the second V-phase coil, and the other ends of the second W-phase coil are required, reducing the number of parts and allowing for a smaller axial gap motor.

[0010] A stator according to a second aspect of this disclosure may include a coil holder that holds the first U-phase coil, the second U-phase coil, the first V-phase coil, the second V-phase coil, the first W-phase coil, and the second W-phase coil. In this case, the coil holder can be formed to surround the rotation axis in the circumferential direction. Furthermore, the other end of the second U-phase coil, the other end of the second V-phase coil, and the other end of the second W-phase coil are located on the outer circumference of the coil holder, and correspondingly, the busbar is held on the outer circumference of the coil holder, so that the coils and the busbar can be connected on the outer circumference of the coil holder away from the rotation axis.

[0011] In a third aspect of this disclosure, the first U-phase coil, the first V-phase coil, the first W-phase coil, the second U-phase coil, the second V-phase coil, and the second W-phase coil may be arranged around the rotation axis in this order. In this case, the first wire extends in an arc along the outer circumference of the coil holder from one end of the first U-phase coil to one end of the second U-phase coil, the second wire extends in an arc along the outer circumference of the coil holder from one end of the first V-phase coil to one end of the second V-phase coil, and the third wire extends in an arc along the outer circumference of the coil holder from one end of the first W-phase coil to one end of the second W-phase coil. With this configuration, the portions of the first, second, and third wires that connect the coils to each other can be arranged on the outer circumference of the coil holder away from the rotation axis.

[0012] In a fourth aspect of this disclosure, the busbar is provided with a first connection hole, a second connection hole, and a third connection hole. This allows for improved workability during assembly, for example, when assembling the first U-phase coil and the second U-phase coil into the coil holder after the busbar has been held in the coil holder, by simply inserting the first wire located on the other end of the second U-phase coil into the first connection hole. Similarly, the V-phase and W-phase can also be assembled using the second and third connection holes to improve workability during assembly.

[0013] In a fifth aspect of this disclosure, the coil holder is provided with a first holding portion, a second holding portion, and a third holding portion. This allows the first wire located at the other end of the first coil of the U phase to be easily held in the coil holder simply by inserting it into the first holding portion. Similarly, the V phase and W phase can be assembled using the second and third holding portions to improve workability during assembly.

[0014] In a sixth aspect of this disclosure, the arc-shaped portion of the first wire, the arc-shaped portion of the second wire, and the arc-shaped portion of the third wire are arranged to overlap each other when viewed from a direction along the axis of rotation, so that the three arc-shaped portions can be arranged in a space-saving manner. [Effects of the Invention]

[0015] As explained above, the first and second coils of the U-phase are integrally formed using a first wire, the first and second coils of the V-phase are integrally formed using a second wire, and the first and second coils of the W-phase are integrally formed using a third wire, thus reducing the number of busbars. This improves assembly efficiency and reduces costs. [Brief explanation of the drawing]

[0016] [Figure 1] This is a front view of an electric pump equipped with an axial gap motor according to an embodiment of the present invention. [Figure 2] This is a cross-sectional view taken along line II-II in Figure 1. [Figure 3] This is an exploded perspective view of the stator. [Figure 4] This is a perspective view of the status. [Figure 5] This is a perspective view showing the coil and busbar assembled into the coil holder. [Figure 6A] This is a plan view of the first and second coils of the U-phase. [Figure 6B] Figure 6A is a cross-sectional view along line BB. [Figure 6C] It is a cross-sectional view taken along line C-C in FIG. 6A. [Figure 7] It is a plan view of a first coil and a second coil of a V-phase. [Figure 8] It is a plan view of a first coil and a second coil of a W-phase. [Figure 9] It is a diagram schematically showing coil connections. [Figure 10] It is a plan view of a bus bar. [Figure 11] It is a view corresponding to FIG. 9 according to another embodiment. MODE FOR CARRYING OUT THE INVENTION

[0017] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following description of preferred embodiments is essentially merely illustrative, and is not intended to limit the present invention, applications thereof, or uses thereof.

[0018] FIG. 1 is an external view showing a centrifugal electric pump 1 including an axial gap motor 2 according to an embodiment of the present invention. In the present embodiment, a case where the electric pump 1 is an electric water pump will be described. Accordingly, the electric pump 1 according to the embodiment of the present invention is for circulating cooling water for cooling various devices mounted on a vehicle within a predetermined path. Examples of the various devices include, but are not limited to, a traction motor, an inverter circuit, an engine, a transmission, an air conditioner, and the like, and the cooling water for other devices can also be circulated. In the description of this embodiment, the upper side of FIG. 1 is referred to as the upper side of the electric pump 1, and the lower side of FIG. 1 is referred to as the lower side of the electric pump 1. This definition is merely for convenience of description, and does not limit the posture during actual use; the electric pump 1 may be used in any posture.

[0019] In the following description, the case where the present invention is applied to the electric pump 1 is described, but the present invention is not limited thereto, and can also be applied to electric pumps that deliver various liquids and gases. Further, the electric pump that delivers gas may be a blower, a fan, a compressor, or the like.

[0020] As shown in Figure 2, the electric pump 1 comprises an axial gap motor 2, a motor housing 3, an impeller 4 rotated by the axial gap motor 2, a housing 5, a circuit board (control board) 6, and a rear member 7. The circuit board 6 is provided with a power supply circuit 6a including a field-effect transistor (FET), etc. The power supply circuit 6a is the part that supplies a predetermined current to coils 21 to 26, which will be described later. Power is supplied to the power supply circuit 6a from, for example, a vehicle battery (not shown).

[0021] The impeller 4 is housed within the housing 5, and the impeller 4 housed within the housing 5 is rotated in a predetermined direction by the axial gap motor 2. In Figure 2, some parts of the electric pump 1 are shown with dashed lines for clarity, but the shape and size of each part are not limited to those shown and can be changed.

[0022] (Housing 5 configuration) The housing 5 is an injection-molded product made, for example, from a resin material. As shown in Figure 1, a suction pipe section 50 that protrudes in the direction of the rotational centerline of the impeller 4 is integrally molded in the central part of the housing 5. An intake port 50a is opened at the tip (upstream end) of the suction pipe section 50. Cooling water that has flowed through an intake-side piping (not shown) is drawn into the intake port 50a.

[0023] The housing 5 has a pump chamber forming wall 51 that extends radially from the base end (downstream end) of the suction pipe section 50, and the side opposite to the protruding direction of the suction pipe section 50 is almost entirely open. Inside the pump chamber forming wall 51, a pump chamber S1 (shown in Figure 2) is formed that communicates with the downstream end of the suction pipe section 50, and the impeller 4 is housed in this pump chamber S1. As shown in Figure 1, a bulge 51a is formed in the pump chamber forming wall 51 at a point radially away from the base end of the suction pipe section 50. The bulge 51a is formed to extend in an arc shape around the rotation centerline of the impeller 4, and inside the bulge 51a, an outflow passage S2 (shown in Figure 2) that communicates with the pump chamber S1 is formed. In other words, the electric pump 1 is configured to draw in fluid in the direction along the rotation centerline by the rotation of the impeller 4, and then discharge it radially.

[0024] As shown in Figure 1, a discharge pipe section 52 is integrally molded in the housing 5, corresponding to the downstream end of the outflow passage S2. The discharge pipe section 52 is formed to protrude in the tangential direction of a virtual circle centered on the rotation center of the impeller 4. The base end (upstream end) of the discharge pipe section 52 communicates with the downstream end of the outflow passage S2. A discharge port 52a (shown only in Figure 1) opens at the tip (downstream end) of the discharge pipe section 52. Discharge-side piping (not shown) communicates with the discharge port 52a, so that the cooling water that has flowed through the discharge pipe section 52 flows into the discharge-side piping.

[0025] (Configuration of motor housing 3) The motor housing 3 is an injection-molded product made, for example, from a resin material, and is formed to cover the housing 5 from the open side. The motor housing 3 has a stator embedding portion 31 in which a plurality of stator cores 20 and a plurality of coils 21 to 26 that constitute the stator 2A of the axial gap motor 2, which will be described later, are embedded and fixed. The stator embedding portion 31 is in the shape of a thick plate. The pump chamber S1 is formed between the stator embedding portion 31 and the pump chamber forming wall portion 51 of the housing 5.

[0026] Furthermore, the motor housing 3 is provided with an annular portion 30 formed to fit inside the pump chamber forming wall portion 51 of the housing 5. The annular portion 30 is formed to protrude into the housing 5 from the peripheral edge of the stator embedding portion 31, and the outer surface of the annular portion 30 and the inner surface of the pump chamber forming wall portion 51 are in close contact with each other. By bringing the outer surface of the annular portion 30 into close contact or bonding the inner surface of the pump chamber forming wall portion 51, watertightness and airtightness between the two are ensured. As another example of joining, the annular portion 30 and the pump chamber forming wall portion 51 can be joined by, for example, spin fusion (welding), which allows the two parts to be joined while eliminating the need for sealing components such as gaskets and bolt fastening, thereby ensuring watertightness and airtightness. Alternatively, without fusion or other methods, the two parts may be joined by bolt fastening with a sealing component 300 such as a gasket interposed between the annular portion 30 and the pump chamber forming wall portion 51. The joint structure between the annular section 30 and the pump chamber forming wall section 51 only needs to ensure watertightness and airtightness, so it is possible to use a joint structure other than the one described above.

[0027] (Configuration of axial gap motor 2) The axial gap motor 2 comprises a plurality of stator cores 20 fixed to the motor housing 3, coils 21-26 wound around each of the stator cores 20, a first magnet 44 and a first back yoke 45, a second magnet 46 and a second back yoke 47, a rotating shaft (pivot shaft) 40, and a bearing 41. In Figure 2, the impeller 4 is located to the right of the stator cores 20 and coils 21-26, and the circuit board 6 is located to the left of the stator cores 20 and coils 21-26, but the configuration is not limited to this, and a configuration with the left and right sides reversed is also possible.

[0028] The axial gap motor 2 is a three-phase motor having U-phase, V-phase, and W-phase. That is, as shown in Figure 3, the axial gap motor 2 has six stator cores 20. The six stator cores 20 are held in one core holder 60. As shown in Figure 4, the bearings 41 are integrated with the center of the core holder 60.

[0029] Furthermore, as shown in Figure 5, the axial gap motor 2 is equipped with six coils corresponding to the stator core 20, namely, the U-phase first coil 21, the U-phase second coil 22, the V-phase first coil 23, the V-phase second coil 24, the W-phase first coil 25, and the W-phase second coil 26. The stator 2A is composed of the six stator cores 20, the U-phase first coil 21, the U-phase second coil 22, the V-phase first coil 23, the V-phase second coil 24, the W-phase first coil 25, and the W-phase second coil 26, the core holder 60, and the coil holder 70.

[0030] As shown in Figure 3, in this example, six stator cores 20 are arranged in a ring shape so as to surround the rotation axis 40 in the circumferential direction, and the circumferential spacing between the six stator cores 20 is set to be equal. The six stator cores 20 are identical and are made of a metal material such as iron, and have a long columnar shape in the direction of the rotation centerline (direction of the rotation axis 40). The cross-section of the stator core 20 in the direction perpendicular to the longitudinal direction is a roughly triangular shape with the apex located at the part closest to the rotation centerline. This cross-sectional shape is roughly the same from one end to the other in the longitudinal direction of the stator core 20. Note that the number of stator cores 20 is not limited to six, but can be set to any number. The number of coils 21 to 26, the shape of the core holder 60, and the shape of the coil holder 70 can be changed according to the number of stator cores 20.

[0031] As shown in Figure 3, the core holder 60 has six core holding portions 61, each holding one of the six stator cores 20, and a connecting plate portion 62 that connects the six core holding portions 61. The core holding portions 61 and the connecting plate portion 62 are integrally molded from an electrically insulating resin material. The six core holding portions 61 correspond to the positions of the six stator cores 20 and are arranged in an annular shape surrounding the rotation centerline. Each core holding portion 61 is cylindrical and is formed to surround the outer circumferential surface of the stator core 20. Since the core holding portions 61 are interposed between the stator core 20 and the coil 21, the core holding portions 61 insulate the stator core 20 from the coil 21.

[0032] The connecting plate portion 62 is disc-shaped and arranged concentrically with the rotation centerline. By connecting the base ends of the six core holding portions 61 arranged in an annular shape, it maintains a predetermined spacing between the six core holding portions 61. The connecting plate portion 62 has a plate-shaped first covering portion 62a that covers one end face of each stator core 20 (the right end face in Figure 2, i.e., the end face on the impeller 4 side). Since there are six stator cores 20, there are also six first covering portions 62a, spaced apart from each other in the circumferential direction of the rotation centerline. Each first covering portion 62a extends along one end face of the stator core 20 and is approximately triangular in shape. The core holding portion 61 is formed to protrude from the peripheral edge of the first covering portion 62a toward the other end of the stator core 20.

[0033] The first U-phase coil 21, the second U-phase coil 22, the first V-phase coil 23, the second V-phase coil 24, the first W-phase coil 25, and the second W-phase coil 26 are also arranged in an annular shape so as to surround the rotating shaft 40 in the circumferential direction, similar to the stator core 20. As shown in Figure 5, the first U-phase coil 21 and the second U-phase coil 22 are paired and arranged to be point-symmetric with respect to the axis of rotation 40. Similarly, the first V-phase coil 23 and the second V-phase coil 24 are paired and arranged to be point-symmetric with respect to the axis of rotation 40. Furthermore, the first W-phase coil 25 and the second W-phase coil 26 are paired and arranged to be point-symmetric with respect to the axis of rotation 40. The first coil 21 of the U phase, the first coil 23 of the V phase, the first coil 25 of the W phase, the second coil 22 of the U phase, the second coil 24 of the V phase, and the second coil 26 of the W phase are arranged around the rotation axis 40 in this order. The winding method and number of turns of each coil 21 to 26 can be set arbitrarily.

[0034] The first coil 21 of the U phase, the second coil 22 of the U phase, the first coil 23 of the V phase, the second coil 24 of the V phase, the first coil 25 of the W phase, and the second coil 26 of the W phase are also held by the core holder 60, but in this example, a coil holder 70 is provided to hold these coils 21 to 26, making the holding of the coils 21 to 26 more secure. That is, the coil holder 70 is formed to surround the rotation axis 40 in the circumferential direction as a whole, and as shown in Figure 3, it has a circumferential wall portion 71 that surrounds the outer circumferential surfaces of the six coils 21 to 26, and an end wall portion 72. The circumferential wall portion 71 and the end wall portion 72 are integrally molded from an electrically insulating resin material. The end wall portion 72 extends in a direction perpendicular to the rotation centerline and has a plate-shaped second covering portion 72a that covers the other end face of the stator core 20 (the left end face in Figure 3, i.e., the end face opposite the impeller 4). Each second covering portion 72a extends along the other end face of the stator core 20 and has a roughly triangular shape. An opening 72b is formed in the center of the end wall portion 72, and the formation of this opening 72b enhances the fluidity of the molten resin during insert molding, which will be described later.

[0035] The peripheral wall portion 71 is the outer circumference of the coil holder 70 and protrudes from the peripheral edge of the end wall portion 72 along the outer circumference of the coil 21. A part of the peripheral wall portion 71 is formed to bulge radially, and the first holding portion 73, the second holding portion 74, and the third holding portion 75 are formed in this radially bulging portion so as to protrude toward the side opposite the impeller. In addition, an opening 71b is formed in the radially bulging portion of the peripheral wall portion 71 to improve the fluidity of the molten resin during insert molding, which will be described later.

[0036] As shown in Figure 6A, the first U-phase coil 21 and the second U-phase coil 22 are integrally formed from a common first wire 101, constituting a single U-phase coil unit Y1. The first wire 101 is made of a conductive wire such as copper wire. When forming the first U-phase coil 21 and the second U-phase coil 22, for example, the first U-phase coil 21 can be formed by winding a single first wire 101 around a columnar core (not shown) a predetermined number of times, and after forming the first U-phase coil 21, the second U-phase coil 22 can be formed by winding the first wire 101 around another part of the same core a predetermined number of times. This results in a U-phase coil unit Y1 in which one end of the first U-phase coil 21 and one end of the second U-phase coil 22 are connected, that is, both coils 21 and 22 are electrically connected.

[0037] The portion of the first wire 101 between the U-phase first coil 21 and the U-phase second coil 22 is a first arc-shaped portion 101a that extends in an arc along the outer circumference of the coil holder 70 from one end of the U-phase first coil 21 to one end of the U-phase second coil 22. In this example, the first arc-shaped portion 101a extends along the outer circumference of the peripheral wall portion 71. As shown in Figure 6B, one end of the U-phase first coil 21 is the upper side in Figure 6B, and the other end of the U-phase first coil 21 is the lower side in Figure 6B. A first power supply connection portion 101b, which is connected to the power supply circuit 6a, is provided on the other end of the U-phase first coil 21. The first power supply connection portion 101b is made of the first wire 101 and protrudes from the other end of the U-phase first coil 21. When the U-phase coil unit Y1 is assembled to the coil holder 70, the first power supply connection part 101b is held in place by being inserted into the through hole formed in the first holding part 73.

[0038] As shown in Figure 6C, one end of the U-phase second coil 22 is at the bottom in Figure 6C, and the other end of the U-phase second coil 22 is at the top in Figure 6C. The other end of the U-phase second coil 22 is provided with a first busbar connection portion 101c, which is connected to a busbar 80 described later. The first busbar connection portion 101c is made of a first wire 101 and protrudes from the other end of the U-phase second coil 22. The protrusion direction of the first power supply connection portion 101b and the protrusion direction of the first busbar connection portion 101c are the same. The first power supply connection portion 101b is formed to be longer than the first busbar connection portion 101c.

[0039] As shown in Figure 7, the first V-phase coil 23 and the second V-phase coil 24 are integrally formed by a common second wire 102, constituting a single V-phase coil unit Y2. The second wire 102 is the same as the first wire 101, and the V-phase coil unit Y2 is formed in the same way as the U-phase coil unit Y1.

[0040] Specifically, the portion of the second wire 102 between the V-phase first coil 23 and the V-phase second coil 24 is a second arc-shaped portion 102a that extends in an arc along the outer circumference of the coil holder 70 from one end of the V-phase first coil 23 to one end of the V-phase second coil 24. Furthermore, a second power supply connection portion 102b, connected to the power supply circuit 6a, is provided at the other end of the V-phase first coil 23. The second power supply connection portion 102b is made of the second wire 102 and protrudes from the other end of the V-phase first coil 23. When the V-phase coil unit Y2 is assembled to the coil holder 70, the second power supply connection portion 102b is held in place by being inserted into a through-hole formed in the second holding portion 74. Additionally, a second busbar connection portion 102c, connected to the busbar 80, is provided at the other end of the V-phase second coil 24. The second busbar connection portion 102c is made of the second wire 102 and protrudes from the other end of the second coil 24 of the V phase. The protrusion direction of the second power supply connection portion 102b and the protrusion direction of the second busbar connection portion 102c are the same. The second power supply connection portion 102b is formed to be longer than the second busbar connection portion 102c.

[0041] As shown in Figure 8, the first W-phase coil 25 and the second W-phase coil 26 are integrally formed by a common third wire 103, constituting a single W-phase coil unit Y3. The third wire 103 is the same as the first wire 101, and the W-phase coil unit Y3 is formed in the same way as the U-phase coil unit Y1.

[0042] Specifically, the portion of the third wire 103 between the W-phase first coil 25 and the W-phase second coil 26 is a third arc-shaped portion 103a that extends in an arc along the outer circumference of the coil holder 70 from one end of the W-phase first coil 25 to one end of the W-phase second coil 26. Furthermore, a third power supply connection portion 103b, connected to the power supply circuit 6a, is provided at the other end of the W-phase first coil 25. The third power supply connection portion 103b is made of the third wire 103 and protrudes from the other end of the W-phase first coil 25. When the W-phase coil unit Y3 is assembled to the coil holder 70, the third power supply connection portion 103b is held in place by being inserted into a through-hole formed in the third holding portion 75. Additionally, a third busbar connection portion 103c, connected to the busbar 80, is provided at the other end of the W-phase second coil 26. The third busbar connection portion 103c is composed of a third wire 103 and protrudes from the other end of the second coil 26 of the W phase. The protruding direction of the third power supply connection portion 103b and the protruding direction of the third busbar connection portion 103c are the same. The third power supply connection portion 103b is formed to be longer than the third busbar connection portion 103c.

[0043] Figure 5 shows the U-phase coil unit Y1, V-phase coil unit Y2, and W-phase coil unit Y3 assembled in the coil holder 70. When viewed from a direction along the rotation axis 40, the first arc-shaped portion 101a of the first wire 101, the second arc-shaped portion 102a of the second wire 102, and the third arc-shaped portion 103a of the third wire 103 are arranged to overlap each other in at least part. This allows the first arc-shaped portion 101a, the second arc-shaped portion 102a, and the third arc-shaped portion 103a to be arranged in a space-saving manner.

[0044] The stator 2A is equipped with a busbar 80. The busbar 80 is made of a conductive metallic material and is a component for electrically connecting the other end of the U-phase second coil 22, the other end of the V-phase second coil 24, and the other end of the W-phase second coil 26. In this embodiment, only one busbar 80 is provided, and therefore the U-phase second coil 22, the V-phase second coil 24, and the W-phase second coil 26 are connected by a common busbar 80.

[0045] Figure 9 schematically shows the wiring of coils 21 to 26. By connecting the second coil 22 of the U phase, the second coil 24 of the V phase, and the second coil 26 of the W phase with the busbar 80, coils 21 to 26 can be configured in a so-called star connection.

[0046] As shown in Figure 10, the busbar 80 is arc-shaped. A first protruding plate portion 81 is formed at one circumferential end of the busbar 80, protruding radially inward. A second protruding plate portion 82 is formed at the circumferential middle of the busbar 80, protruding radially inward. A third protruding plate portion 83 is formed at the other circumferential end of the busbar 80, protruding radially inward. A first connection hole 81a is formed through the first protruding plate portion 81, to which the first busbar connection portion 101c, provided on the other end side of the U-phase second coil 22, is inserted and electrically connected. A second connection hole 82a is formed through the second protruding plate portion 82, to which the second busbar connection portion 102c, provided on the other end side of the V-phase second coil 24, is inserted and electrically connected. The third protruding plate portion 83 has a through-hole 83a formed therein, through which the third busbar connection portion 103c, which is provided on the other end side of the second coil 26 of the W phase, is electrically connected when inserted.

[0047] The other end of the second coil 22 of the U phase, the other end of the second coil 24 of the V phase, and the other end of the second coil 26 of the W phase are located on the outer circumference of the coil holder 70. Accordingly, the first busbar connection portion 101c, the second busbar connection portion 102c, and the third busbar connection portion 103c are also located on the outer circumference of the coil holder 70. Correspondingly, the busbar 80 is held on the outer circumference of the coil holder 70.

[0048] As shown in Figure 4, the bearing 41 is formed in a cylindrical shape extending in the direction of the rotational centerline and is fixed to the motor housing 3 in a non-rotatable manner as described above. The rotating shaft 40 shown in Figure 2 is a hollow shaft that is rotatably supported while inserted through the bearing 41, and the length of the rotating shaft 40 is set to be longer than the length of the bearing 41. Therefore, when supported by the bearing 41, one end of the rotating shaft 40 (the end on the impeller 4 side) protrudes from one end of the bearing 41, and the other end of the rotating shaft 40 (the end opposite the impeller 4) protrudes from the other end of the bearing 41. Although not shown, the rotating shaft 40 may be a non-rotating support shaft fixed to the motor housing 3, and the bearing 41 may be rotatably arranged relative to this support shaft.

[0049] The radial center of the impeller 4 is fixed to one end of the rotating shaft 40. Specifically, a female thread is formed on the inner surface of one end of the rotating shaft 40, and the shaft of the bolt E is passed through the radial center of the impeller 4 and then screwed into the female thread of the rotating shaft 40, thereby fastening and fixing the impeller 4 to the rotating shaft 40 in a way that prevents relative rotation.

[0050] The first magnet 44 and the first back yoke 45 are disposed between the impeller 4 and the stator core 20 and are fixed to the stator core 20 side of the impeller 4. The first back yoke 45 is also fastened together with the impeller 4 to the rotating shaft 40 by bolts E. The first magnet 44 and the first back yoke 45 are covered with a resin covering material 48. Since the impeller 4 is a component fixed to one end of the rotating shaft 40 in a non-rotatable manner, the first magnet 44 and the first back yoke 45 fixed to the impeller 4 are also fixed to one end of the rotating shaft 40 in a non-rotatable manner. With the first magnet 44 fixed to one end of the rotating shaft 40, the first magnet 44 and one end face of the stator core 20 are arranged so that there is a predetermined gap between them in the direction of the rotational centerline.

[0051] The second magnet 46 and the second back yoke 47 are located on the circuit board 6 side and are fixed to the other end of the rotating shaft 40. Specifically, a female threaded portion (not shown) similar to that of one end is formed on the inner surface of the other end of the rotating shaft 40, and the second back yoke 47 is fastened and fixed to the rotating shaft 40 by passing the shaft portion of the bolt F through the radial center of the second back yoke 47 and then screwing it into the female threaded portion of the rotating shaft 40. The second magnet 46 is fixed to the second back yoke 47 and the second magnet 46 is covered with a resin covering material 49. Therefore, the other end face of the stator core 20 and the second magnet 46 are arranged to be aligned in the direction of the rotational centerline.

[0052] The first magnet 44 and the second magnet 46 can be made of, for example, resin magnets. The first magnet 44 and the second magnet 46 are formed in a disc shape. The first magnet 44 and the second magnet 46 have multiple north pole portions and south pole portions arranged alternately around the rotation axis 40. The positions of the first magnet 44 and the second magnet 46 relative to the stator core 20 are set so that the distance between the first magnet 44 and the second magnet 46 and the stator core 20 is as small as possible.

[0053] The first back yoke 45 and the second back yoke 47 are also formed in a disc shape and are laminated on the side of the first magnet 44 and the second magnet 46 opposite to the stator core 20, respectively, and integrated with the first magnet 44 and the second magnet 46. The outer diameters of the first back yoke 45 and the second back yoke 47 may be set to be larger than or about the same as the outer diameters of the first magnet 44 and the second magnet 46.

[0054] The electric pump 1 is equipped with a cover 8 that covers the second back yoke 47 from the opposite side of the stator core 20. This cover 8 closes off the internal space of the motor housing 3 at the other end. The cover 8 is made of a material with high thermal conductivity, such as aluminum alloy. A circuit board 6 for controlling the axial gap motor 2 is disposed on the outside of the cover 8 in contact with the cover 8. A heat-generating power supply circuit 6a is mounted on the circuit board 6. The circuit board 6 is covered by a rear member 7. The rear member 7 is fastened and fixed to the cover 8 together with the circuit board 6. The rear member 7 is also made of a material with high thermal conductivity, such as aluminum alloy.

[0055] (Manufacturing method for axial gap motor 2) Next, a method for manufacturing the axial gap motor 2 configured as described above will be explained. First, a core holder 60 and a coil holder 70 are prepared. The core holder 60 and the coil holder 70 are components obtained by molding a primary resin (primary molding), and are made of a resin other than an electromagnetic shielding resin. The core holder 60 holds the stator core 20. It is also possible to insert-molde six stator cores 20 during primary molding, in which case it is not necessary for the core holder 60 to hold six stator cores 20. The core holder 60 and the coil holder 70 do not have to be molded at the same time, and therefore the resins of the core holder 60 and the coil holder 70 do not have to be the same.

[0056] Furthermore, as shown in Figure 5, the busbar 80 is assembled and held in the coil holder 70. Next, the U-phase coil unit Y1 is assembled to the coil holder 70. For example, after positioning the U-phase coil unit Y1 above the coil holder 70, it is moved downward. At this time, since both the first power supply connection part 101b and the first busbar connection part 101c are in a position that protrudes in the direction of movement of the U-phase coil unit Y1 (downward), the first power supply connection part 101b and the first busbar connection part 101c can be inserted into the first holding part 73 of the coil holder 70 and the first connection hole 81a of the busbar 80, respectively. This improves workability during assembly.

[0057] Furthermore, the first U-phase coil 21 and the second U-phase coil 22 are formed continuously from a single first wire 101 and have no connecting parts, thus reducing assembly man-hours and improving reliability. In addition, since the first U-phase coil 21 and the second U-phase coil 22 are integrated, during assembly, the relative positional relationship between the first U-phase coil 21 and the second U-phase coil 22 can be maintained, making automatic assembly easy, for example, by an automatic assembly device (not shown).

[0058] Furthermore, by positioning the portion between the first U-phase coil 21 and the second U-phase coil 22 in the U-phase coil unit Y1 on the outer circumference, it can be aligned with the primary molded product. This suppresses displacement of the coil due to resin pressure / flow during secondary molding, and also suppresses exposure to the product surface.

[0059] Similarly, the V-phase coil unit Y2 can be assembled to the coil holder 70, in which case the second power supply connection part 102b and the second busbar connection part 102c can be inserted into the second holding part 74 of the coil holder 70 and the second connection hole 82a of the busbar 80, respectively. Similarly, the W-phase coil unit Y3 can be assembled to the coil holder 70, in which case the third power supply connection part 103b and the third busbar connection part 103c can be inserted into the third holding part 75 of the coil holder 70 and the third connection hole 83a of the busbar 80, respectively. Note that the assembly order of the U-phase coil unit Y1, V-phase coil unit Y2, and W-phase coil unit Y3 to the coil holder 70 is not limited to the order described above and can be set arbitrarily. The first busbar connection part 101c, the second busbar connection part 102c, and the third busbar connection part 103c are soldered to the busbar 80.

[0060] The core holder 60 is insert-molded into the motor housing 3. The coil holder 70 is also insert-molded into the motor housing 3 while fixed to the core holder 60. In other words, the stator 2A is insert-molded into the motor housing 3.

[0061] In other words, as described above, the core holder 60 holds the six stator cores 20, and the coils 21-26 and busbar 80 are held in the coil holder 70 to obtain the stator 2A. Then, the stator 2A is placed in a mold (not shown) for molding the motor housing 3, positioned, and after clamping, molten resin (secondary resin) is injected into the mold to perform secondary molding. After the molten resin has solidified, the mold is removed to obtain a motor housing (secondary molded product) 3 with the stator 2A insert-molded. Note that the core holder 60 and coil holder 70 do not need to be assembled, and it is also possible to place them separately in the secondary molding mold and perform insert molding.

[0062] The first power connection section 101b, the second power connection section 102b, and the third power connection section 103b protrude from the motor housing 3 toward the side opposite the impeller 4 and are exposed to the outside of the motor housing 3. When the circuit board 6 is assembled to the motor housing 3, the first power connection section 101b, the second power connection section 102b, and the third power connection section 103b are connected to the power supply circuit 6a.

[0063] By insert molding a core holder 60, which integrates the stator core 20 and coils 21-26, into the motor housing 3, the stator core 20 and coils 21-26 can be fixed in precise positions relative to the motor housing 3. Furthermore, since multiple coils 21-26 are held by the coil holder 70, the relative positioning of the coils 21-26 can be precisely controlled.

[0064] The bearing 41 can also be insert-molded. That is, when the stator 2A is housed in the mold, the bearing 41 is also housed and positioned at the same time. Subsequently, as the resin for secondary molding solidifies, a secondary molded product is obtained in which the bearing 41 is fixed in a predetermined position in the motor housing 3.

[0065] For example, the housing 5 and secondary resin can be made of, for example, an electromagnetic shielding resin. An electromagnetic shielding resin is a resin capable of shielding electromagnetic waves and is a conventionally known material. For example, an electromagnetic shielding resin material obtained by compounding conductive carbon fibers into a base resin material can be used. For example, a carbon fiber reinforced thermoplastic resin with polyphenylene sulfide as the base resin is preferred, but is not limited to this. On the other hand, the core holder 60, coil holder 70, and covering materials 48 and 49 are formed of resins other than electromagnetic shielding resins.

[0066] (Effects of the embodiment) As described above, according to this embodiment, since the U-phase first coil 21 and the U-phase second coil 22 are integrally formed by the first wire 101, a dedicated busbar for connecting the two coils 21 and 22 is not required. Similarly, since the V-phase first coil 23 and the V-phase second coil 24 are integrally formed by the second wire 102, a dedicated busbar for connecting the two coils 23 and 24 is not required. Furthermore, since the W-phase first coil 25 and the W-phase second coil 26 are integrally formed by the third wire 103, a dedicated busbar for connecting the two coils 25 and 26 is also not required. Therefore, only one busbar 80 is needed, which reduces the number of parts and allows for miniaturization of the axial gap motor 2. In addition, the reduction in the number of parts improves assembly workability and reduces costs.

[0067] The embodiments described above are merely illustrative in all respects and should not be interpreted restrictively. Furthermore, any modifications or changes that fall within the equivalent scope of the claims are all within the scope of the present invention.

[0068] In the above embodiment, the busbar 80 is configured to be assembled to the coil holder 70, but the invention is not limited to this configuration, and the busbar 80 may be insert-molded during the injection molding of the coil holder 70.

[0069] Furthermore, in the above embodiment, the first busbar connection portion 101c, the second busbar connection portion 102c, and the third busbar connection portion 103c are soldered to the busbar 80, but the connection method is not limited to this, and for example, the connection may be made by fusing or by laser welding.

[0070] Furthermore, although the above embodiment described an example of a total of 6 coils with 2 coils x 3 phases, the present invention is not limited to this, and can also be applied to a total of 9 coils with 3 coils x 3 phases, as shown in Figure 11. In other words, the number of coils is not limited. As shown in Figure 11, a third coil 200 of the U phase is provided between the first coil 21 of the U phase and the second coil 22 of the U phase, a third coil 201 of the V phase is provided between the first coil 23 of the V phase and the second coil 24 of the V phase, and a third coil 202 of the W phase is provided between the first coil 25 of the W phase and the second coil 26 of the W phase.

[0071] As shown in Figure 11, the coils 21, 22, and 200 are integrally formed by the first wire 101, with one end of the U-phase first coil 21 and one end of the U-phase second coil 22 connected via the U-phase third coil 200. Furthermore, the coils 23, 24, and 201 are integrally formed by the second wire 102, with one end of the V-phase first coil 23 and one end of the V-phase second coil 24 connected via the V-phase third coil 201. Furthermore, the coils 25, 26, and 202 are integrally formed by the third wire 103, with one end of the W-phase first coil 25 and one end of the W-phase second coil 26 connected via the W-phase third coil 202. [Industrial applicability]

[0072] As explained above, the axial gap motor relating to this disclosure can be used, for example, in an electric water pump mounted on an automobile. [Explanation of symbols]

[0073] 2 Axial gap motor 2A Stator 3 Motor housing 4 impellers 20 stator cores 21. First coil of the U phase 22 U-phase second coil 23 V-phase first coil 24V phase second coil 25 W Phase 1 Coil 26 W-phase second coil 44 First Magnet 70 Coil Holder 73 1st holding part 74 Second holding part 75 Third holding part 80 Bus Bar 81a First connection hole 82a Second connection hole 83a Third connection hole 101 First wire 102 Second wire 103 Third wire

Claims

1. In a three-phase axial gap motor, a stator having a first U-phase coil, a second U-phase coil, a first V-phase coil, a second V-phase coil, a first W-phase coil, and a second W-phase coil, and a magnet fixed to the rotating shaft are arranged with a predetermined gap in the direction of the rotating shaft, The first coil of the U-phase and the second coil of the U-phase are integrally formed with a first wire, such that one end of the first coil of the U-phase and one end of the second coil of the U-phase are connected. The first coil of the V-phase and the second coil of the V-phase are integrally formed with a second wire connecting one end of the first coil of the V-phase and one end of the second coil of the V-phase. The first coil of the W phase and the second coil of the W phase are integrally formed with a third wire connecting one end of the first coil of the W phase and one end of the second coil of the W phase. The other end of the first coil of the U phase, the other end of the first coil of the V phase, and the other end of the first coil of the W phase are connected to a power supply circuit. The other end of the second coil of the U phase, the other end of the second coil of the V phase, and the other end of the second coil of the W phase are connected by a common busbar. The stator includes a coil holder that holds the first coil of the U phase, the second coil of the U phase, the first coil of the V phase, the second coil of the V phase, the first coil of the W phase, and the second coil of the W phase. The coil holder is formed to surround the rotation axis in the circumferential direction, The other end of the second coil of the U phase, the other end of the second coil of the V phase, and the other end of the second coil of the W phase are arranged on the outer circumference of the coil holder. The axial gap motor is characterized in that the busbar is held on the outer circumference side of the coil holder.

2. In the axial gap motor according to claim 1, The first coil of the U phase, the first coil of the V phase, the first coil of the W phase, the second coil of the U phase, the second coil of the V phase, and the second coil of the W phase are arranged in this order around the rotation axis. The first wire extends in an arc shape along the outer circumference of the coil holder from one end of the first coil of the U-phase to one end of the second coil of the U-phase, The second wire extends in an arc shape along the outer circumference of the coil holder from one end of the first coil of the V phase to one end of the second coil of the V phase, The axial gap motor is characterized in that the third wire extends in an arc shape along the outer circumference of the coil holder from one end of the first coil of the W phase to one end of the second coil of the W phase.

3. In the axial gap motor according to claim 1, An axial gap motor characterized in that the busbar has a first connection hole into which the first wire located at the other end of the second coil of the U phase is inserted and connected, a second connection hole into which the second wire located at the other end of the second coil of the V phase is inserted and connected, and a third connection hole into which the third wire located at the other end of the second coil of the W phase is inserted and connected.

4. In the axial gap motor according to claim 3, An axial gap motor characterized in that the coil holder is provided with a first holding portion into which the first wire located at the other end of the first coil of the U phase is inserted and connected; a second holding portion into which the second wire located at the other end of the first coil of the V phase is inserted and connected; and a third holding portion into which the third wire located at the other end of the first coil of the W phase is inserted and connected.

5. In the axial gap motor according to claim 2, An axial gap motor characterized in that the arc-shaped portion of the first wire, the arc-shaped portion of the second wire, and the arc-shaped portion of the third wire are arranged to overlap each other when viewed from a direction along the rotation axis.

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