electric motor

Abstract

An axle of an electric motor has a cylindrical first axle extending in an axial direction, a cover portion disposed at an end portion of the first axle in one of the axial directions, a second axle extending from the cover portion in the one of the axial directions, a first axle through-hole penetrating the first axle in a radial direction, and a second axle through-hole communicating with an inside of the first axle and an outside space of the axle. The cover portion and the second axle have electrical conductivity. The second axle through-hole is disposed at the one of the axial directions than the first axle through-hole. The second axle contacts with a de-electrization device electrically connecting the axle and a housing of the electric motor.

Description

Technical Field

[0001] This invention relates to an electric motor. Background Technology

[0002] Previously, a grounding device for grounding the output shaft of an electric motor was known. For example, the grounding member of the grounding device makes axial contact with the center of the output shaft's end face. (See, for example, Japanese Patent Application Publication No. 2019-192491).

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2019-192491 Summary of the Invention

[0006] However, when cooling the motor by allowing the refrigerant inside the hollow output shaft to flow out through the radial through-hole by rotation, the pressure difference draws the refrigerant from the other axial end of the output shaft into the interior of the output shaft by suction from the axial end. Therefore, in the aforementioned grounding device, it is difficult to achieve cooling using such a hollow output shaft.

[0007] The purpose of this invention is to balance the cooling of the electric motor using a cylindrical shaft and the discharge of the shaft by a power removal device.

[0008] The exemplary electric motor of the present invention includes a shaft, a rotor, a stator, bearings, a housing, and a current-eliminating device. The shaft has a first, cylindrical shaft extending axially. The rotor is supported by the first shaft and is rotatable with the shaft. The stator is disposed radially outward from the rotor. The bearings support the first shaft to enable rotation. The housing houses the rotor, the stator, and the bearings. The current-eliminating device electrically connects the shaft to the housing. The shaft also has a cover, a second shaft, a first shaft through-hole, and a second shaft through-hole. The cover is disposed at one axial end of the first shaft. The second shaft extends axially from the cover. The first shaft through-hole radially penetrates the first shaft. The second shaft through-hole communicates with the interior and exterior spaces of the first shaft. The cover and the second shaft are conductive. The second shaft through-hole is disposed axially outward from the first shaft through-hole. The second shaft contacts the current-eliminating device.

[0009] According to the exemplary electric motor of the present invention, both cooling of the electric motor using a cylindrical shaft and discharge of the shaft achieved by the electric discharge device can be achieved. Attached Figure Description

[0010] Figure 1 This is a conceptual diagram representing the structure of an electric motor.

[0011] Figure 2 This is a conceptual diagram showing an enlarged representation of the main structural components of an electric motor.

[0012] Figure 3 This is a schematic diagram illustrating an example of a vehicle equipped with an electric motor.

[0013] Figure 4A This is a diagram showing an example of the contact between the second shaft and the de-energizing device.

[0014] Figure 4B This is a diagram showing a first modified example of the contact between the second shaft and the de-energizing device.

[0015] Figure 4C This is a diagram showing a second variation of the contact between the second shaft and the de-energizing device.

[0016] Figure 5 This is a diagram showing another configuration example of the first shaft through hole.

[0017] Figure 6A This shows a first configuration example of the second through hole in the cover.

[0018] Figure 6B This shows a second configuration example of the second through hole in the cover.

[0019] Figure 6C This shows a third configuration example of the second through hole in the cover.

[0020] Figure 7 This represents an example of a second shaft through hole configured on the first shaft.

[0021] Figure 8 This is the first variation of the cover.

[0022] Figure 9 This is the second variation of the cover.

[0023] Figure 10 This is the third variation of the cover.

[0024] Figure 11 This is the fourth variation of the cover.

[0025] Figure 12 This is the first example of a deformed shaft.

[0026] Figure 13 This is the second variation of the shaft.

[0027] Figure 14 This is the third variation of the shaft.

[0028] (Symbol Explanation)

[0029] 100 Electric motor; 200 Battery; 300 Vehicle; 1 Electric motor section; 11 Rotor; 111 Rotor core; 1111 Rotor through hole; 112 Magnet; 12 Stator; 121 Stator core; 122 Coil section; 1221 Coil edge; 2 Shaft; 201 First shaft through hole; 202 Second shaft through hole; 21 First shaft; 211 Hollow section; 212 Shaft cylinder section; 213 Inlet; 214 Third chamfered section; 22 Cover section; 221 Hole section; 222 First fixing section; 223 Second fixing section; 224 First chamfered section; 23 Third Two shafts; 24 cover cylinder; 241 second chamfered part; 3 power transmission device; 31 reduction device; 311 main drive gear; 312 intermediate driven gear; 313 final drive gear; 314 intermediate shaft; 32 differential device; 321 gear ring; 4 housing; 401 motor storage space; 402 gear storage space; 41 first housing cylinder; 42 side plate; 4201 side plate through hole; 4202 first output shaft through hole; 421, 422, 423, 424 bearing retaining parts; 4211 bearing; 4221 bearing; 42 31 First intermediate bearing; 4241 First output bearing; 43 Motor cover; 431 Cover; 4311 Opening; 4312 Bearing retainer; 4313 Sealing member; 4314 Bearing; 432 Cylindrical part; 433 Plate part; 4331 Opening; 434 Bearing retainer; 4341 Bearing; 435 Sealing member; 44 Cover member; 440 Storage space; 441 First cover; 442 Second cover; 443 Through hole; 444 Cylindrical part; 445 Filter; 45 Second outer casing cylindrical part; 46 Gear cover; 460 Two output shaft through holes; 461, 462, 463 bearing retaining parts; 4611 bearing; 4621 second intermediate bearing; 4631 second output bearing; 464 receiving plate part; 465 oil passage; 6 liquid circulation part; 61 piping part; 62 pump; 63 oil cooler; 64 motor oil storage part; 7 static elimination device; 71 conductive component; 72 elastic component; 73 retaining component; 74 fixing component; CL lubricant; P liquid storage part; Ds output shaft; J1 first rotating axis; J2 second rotating axis; J3 third rotating axis. Detailed Implementation

[0030] Hereinafter, exemplary embodiments will be described with reference to the accompanying drawings.

[0031] In this specification, the direction parallel to the first rotation axis J1 of the motor unit 1 is defined as the "axial direction" of the motor 100. Regarding the axial direction, as follows... Figure 1As shown, one side of the motor unit 1 is designated as the axial direction D1, and the other side of the power transmission device 3 is designated as the axial direction D2. Furthermore, the radial direction orthogonal to the specified axis is simply referred to as "radial," and the circumferential direction centered on the specified axis is simply referred to as "circumferential." In addition, in this specification, "parallel direction" includes not only perfectly parallel directions but also approximately parallel directions. Furthermore, "extending" along a specified direction or plane includes not only strictly extending along the specified direction but also extending along a direction inclined at less than 45° relative to the strictly specified direction.

[0032] <1. Implementation Method>

[0033] Figure 1 This is a conceptual diagram representing a structural example of an electric motor 100. Figure 2 This is a conceptual diagram showing an enlarged representation of the main structural components of the electric motor 100. Figure 3 This is a schematic diagram illustrating an example of a vehicle 300 equipped with an electric motor 100. Additionally, Figure 1 and Figure 2 This is just a conceptual diagram; the configuration and dimensions of each part may not be the same as the actual motor 100. Furthermore, Figure 2 It is magnification Figure 1 The diagram shows the portion X enclosed by dashed lines. Furthermore, Figure 3 The concept illustration depicts vehicle 300.

[0034] In this embodiment, the electric motor 100 is as follows Figure 3 The vehicle 300 shown is equipped with at least one electric motor as a power source, such as a hybrid electric vehicle (HV), a plug-in hybrid electric vehicle (PHV), or an electric vehicle (EV). The electric motor 100 serves as the power source for the vehicle 300. The vehicle 300 has the electric motor 100 and a battery 200. The battery 200 stores electricity for supplying to the electric motor 100. Taking the vehicle 300 as an example, the electric motor 100 drives the left and right front wheels. Alternatively, the electric motor 100 only needs to drive at least one wheel.

[0035] like Figure 1 As shown, the electric motor 100 includes an electric motor section 1, a shaft 2, a power transmission device 3, a housing 4, and a fluid circulation section 6. The shaft 2 extends axially along a first rotation axis J1. The shaft 2 is rotatable about the first rotation axis J1. The housing 4 houses the electric motor section 1, the shaft 2, and the power transmission device 3. For example, the housing 4 houses the rotor 11, the stator 12 of the electric motor section 1 (described later), and the bearings 4211 and 4314 (described later).

[0036] Furthermore, the electric motor 100 also includes a current-eliminating device 7 having a conductive member 71. The current-eliminating device 7 electrically connects the shaft 2 and the housing 4. The current-eliminating device 7 is fixed to the housing 4 and contacts the shaft 2. Figure 2 As shown, the current removal device 7 of this embodiment also includes an elastic member 72, a retaining member 73, and a fixing member 74.

[0037] The conductive member 71 is formed using a conductive material. The front end of the conductive member 71 contacts the second shaft 23 (described later) of the shaft 2. In this embodiment, the conductive member 71 is a molded body, but it is not limited to the example described above and may also be brush-shaped. The material of the conductive member 71 is preferably a material with good sliding properties, and more preferably a material with a low coefficient of friction. The material of the conductive member 71 can be, for example, a composite resin containing conductive fillers such as carbon fiber or metal.

[0038] The elastic member 72 is housed inside the retaining member 73 in a compressed state. Through its elasticity, the elastic member 72 presses the conductive member 71 against the second shaft 23. In this embodiment, a helical spring is used as the elastic member 72, but it is not limited to the example described above; other types of members such as leaf springs or rubber can also be used.

[0039] The retaining member 73 is a bottomed cylindrical shape, housing a portion of the conductive member 71 and the elastic member 72 inside. The retaining member 73 retains the conductive member 71. Specifically, the retaining member 73 holds the end of the conductive member 71 on the side of the elastic member 72 so that it can move in the direction in which the retaining member 73 extends. Furthermore, the retaining member 73 holds the elastic member 72 so that it can extend and retract in the direction in which the retaining member 73 extends.

[0040] The fixing member 74 secures the electrostatic discharge device 7 to the housing 4. In this embodiment, the fixing member 74 is mounted on the retaining member 73. Furthermore, at least one fixing member 74 is fixed to the plate portion 433 described later (for example, see the following description). Figure 4A However, not limited to the above examples, at least one fixing member 74 may be fixed to the cover member 44 described later. That is, the fixing member 74 will keep the member 73 fixed to at least one of the plate portion 433 and the cover member 44.

[0041] Furthermore, the fixing member 74 is conductive and is electrically connected to the conductive member 71. By fixing the fixing member 74 to the conductive plate portion 433 or the cover member 44, the conductive member 71 is electrically connected to the outer casing 4.

[0042] <1-1. Electric Motor Section 1>

[0043] Next, refer to Figure 1 and Figure 2The motor section 1 will be described below. Motor section 1 is a brushless DC motor. Motor section 1 is the drive source for motor 100 and is driven by power from an inverter (not shown). Motor section 1 is an inner rotor type motor section in which the rotor 11 is rotatably disposed inside the stator 12. Figure 1 As shown, the motor section 1 has a rotor 11 and a stator 12.

[0044] <1-1-1. Rotor 11>

[0045] Rotor 11 is supported on shaft 2. Motor 100 includes rotor 11. Rotor 11 is rotatable with shaft 2. Specifically, rotor 11 is supported on first shaft 21, described later. Rotor 11 rotates by supplying electricity from the power supply unit (not shown) of motor 100 to stator 12. Rotor 11 has a rotor core 111 and magnets 112. Rotor core 111 is, for example, formed by stacking thin sheet-like electromagnetic steel plates. Rotor core 111 is a cylinder extending axially and fixed to the radially outer surface of first shaft 21. A plurality of magnets 112 are fixed at rotor core 111. The plurality of magnets 112 arrange magnetic poles alternately along the circumferential direction.

[0046] Furthermore, the rotor core 111 has a rotor through-hole 1111. The rotor through-hole 1111 extends axially through the rotor core 111 and is connected to the first shaft through-hole 201. The rotor through-hole 1111 serves as a flow path for the lubricating fluid CL, which functions as a refrigerant. When the rotor 11 rotates, the lubricating fluid CL flowing in the hollow portion 211 of the first shaft 21 can flow into the rotor through-hole 1111 via the first shaft through-hole 201. In addition, the lubricating fluid CL flowing into the rotor through-hole 1111 can flow out to the outside from both axial ends of the rotor through-hole 1111. The outflowing lubricating fluid CL flies toward the stator 12, for example, to cool the coil portion 122 (especially the coil edge 1221). In addition, the outflowing lubricating fluid CL flies toward the bearings 4211, 4314, etc., which support the first shaft 21 to rotate, to lubricate and cool the bearings 4211, 4314.

[0047] <1-1-2. Stator 12>

[0048] The stator 12 is positioned radially outward from the rotor 11. The motor 100 includes a stator 12. The stator 12 has a stator core 121 and a coil portion 122. The stator 12 is sandwiched between the stator core 121 and the coil portion 122. The stator 12 is held in the first outer casing 41, described later. The stator core 121 has a plurality of pole teeth (not shown) extending radially inward from the inner circumferential surface of the annular yoke. The coil portion 122 is formed by winding a wire around the pole teeth via an insulator (not shown). The coil portion 122 has a coil end 1221 protruding from the axial end face of the stator core 121.

[0049] <1-2. Axis 2>

[0050] like Figure 1 As shown, shaft 2 is supported by housing 4 and is rotatable via bearings 4211, 4221, 4314, and 4611 (described later). In other words, motor 100 includes bearings 4211, 4221, 4314, and 4611. Bearings 4211, 4221, 4314, and 4611 support the first shaft 21 and enable it to rotate.

[0051] Shaft 2 has a first shaft 21. As previously described, the motor 100 includes shaft 2. The first shaft 21 is cylindrical, extending axially. Refrigerant flows inside the first shaft 21. The motor 100 also includes the aforementioned refrigerant. In this embodiment, the refrigerant is a lubricating fluid CL. Depending on the rotation of shaft 2, the refrigerant flowing inside the first shaft 21 can be supplied to the stator 12 and bearings 4211, 4314, etc., through the first shaft through-hole 201 described later. Therefore, the stator 12 (especially the coil edge 1221 of the coil section 122) and bearings 4211, 4314, etc., can be cooled by the refrigerant.

[0052] The first shaft 21 has a hollow portion 211, a shaft sleeve portion 212, and an inlet 213. The shaft sleeve portion 212 extends axially along a first rotation axis J1. The hollow portion 211 is disposed inside the shaft sleeve portion 212. The inlet 213 is disposed on the other axial side D2 of the shaft sleeve portion 212 and is connected to the oil passage 465 of the gear cover portion 46 (described later). The lubricating fluid CL (described later) flows into the hollow portion 211 from the oil passage 465 via the inlet 213.

[0053] Alternatively, the first shaft 21 can be split at the middle portion in the axial direction. When the first shaft 21 is split, the split first shaft 21 can, for example, employ a threaded coupling structure using both external and internal threads. Furthermore, it can be joined by fixing methods such as press-fitting or welding. When using fixing methods such as press-fitting or welding, a serration structure combining concave and convex portions extending along the axial direction can also be used. With the above structure, rotation can be reliably transmitted.

[0054] Furthermore, shaft 2 also includes a cover portion 22, a second shaft 23, a first shaft through hole 201, and a second shaft through hole 202. The cover portion 22 is disposed at one axial end of the first shaft 21. The second shaft 23 extends from the cover portion 22 axially to one direction D1. The first shaft through hole 201 penetrates radially through the first shaft 21. The second shaft through hole 202 communicates with the interior of the first shaft 21 and the external space of shaft 2. The second shaft through hole 202 is disposed axially to one direction D1 further than the first shaft through hole 201. The first shaft 21, the cover portion 22, and the second shaft 23 are conductive and are made of metal in this embodiment. The second shaft 23 is in contact with the current-eliminating device 7.

[0055] Since the second shaft through-hole 202, located axially to the side D1 of the first shaft through-hole 201, is provided on the shaft 2, by drawing air through the second shaft through-hole 202, the lubricating fluid CL, which serves as a refrigerant, can be drawn into the interior from the axial side D2 of the second shaft 21 through the pressure difference. Therefore, by rotating, the lubricating fluid CL inside the cylindrical first shaft 21 can flow out from the first shaft through-hole 201 and cool the motor section 1 (especially the coil section 122 of the stator 12). Moreover, the shaft 2 is electrically connected to the housing 4 by contacting the second shaft 23 through the current-eliminating device 7. Therefore, the current generated by the potential change generated inside the shaft 2 can be released to the housing 4 via the current-eliminating device 7. Thus, the cooling of the motor section 1 achieved by the refrigerant (in this embodiment, the lubricating fluid CL) inside the cylindrical first shaft 21 and the discharge of the shaft 2 achieved by the current-eliminating device 7 can be achieved simultaneously.

[0056] <1-2-1. Second Axis 23>

[0057] The second shaft 23 extends axially along the first rotation axis J1. The outer diameter of the second shaft 23 is smaller than the outer diameter of the first shaft 21.

[0058] As previously mentioned, the de-energizer 7 is in contact with the second shaft 23. Figure 4A This is a diagram showing an example of the contact between the second shaft 23 and the de-energizing device 7. Figure 4B This is a diagram showing a first modified example of the contact between the second shaft 23 and the de-energizing device 7. Figure 4C This is a diagram showing a second modified example of the contact between the second shaft 23 and the de-energizing device 7. Preferably, as shown... Figure 4A and Figure 4B As shown, the de-energizer 7 contacts at least a portion of the circumferential region of the radially outer surface of the second shaft 23. For example, in this embodiment, as... Figure 4A As shown, the de-energizer 7 contacts a portion of the circumferential region of the radially outer surface of the second shaft. Alternatively, it can also be as follows... Figure 4B As shown, the conductive member 71 of the current-eliminating device 7 is in contact with the entire circumferential region of the radially outer surface of the second shaft 23. By making the current-eliminating device 7 contact at least a portion of the circumferential region of the radially outer surface of the second shaft 23, which has an outer diameter smaller than the first shaft 21, the sliding area of ​​the current-eliminating device 7 relative to the second shaft 23 per revolution of the shaft 2 can be further reduced. Therefore, wear powder generated at the contact portion between the current-eliminating device 7 and the shaft 2 can be reduced. Furthermore, not limited to the above example, the current-eliminating device 7 can also be as follows... Figure 4C As shown, it contacts one end of the second shaft in the axial direction.

[0059] <1-2-2. First shaft through hole 201>

[0060] Furthermore, a first shaft through-hole 201 is disposed in the shaft sleeve portion 212 and extends radially through the shaft sleeve portion 212. When the shaft 2 rotates, the lubricating fluid CL inside the first shaft 21 flows out through the first shaft through-hole 201 from the hollow portion 211 to the outside of the first shaft 21 under the action of centrifugal force. In this embodiment, as... Figure 1 As shown, the first shaft through hole 201 is located at a position D2 on one side of the axial direction and D1 on the other side of the axial direction of the rotor 11, and is connected to the rotor through hole 1111 as described above.

[0061] However, it is not limited to Figure 1 As an example, the first shaft through hole 201 can be disposed at either one axial end D1 relative to the axial direction of the rotor 11, or at the other axial end D2 relative to the axial direction of the rotor 11. That is, at least a portion of the first shaft through hole 201 can be disposed at at least one of the above-mentioned positions. Figure 5 This is a diagram showing another configuration example of the first shaft through hole 201. For example, as shown... Figure 5 As shown, at least a portion of the first shaft through-hole 201 may be positioned axially to the rotor 11 at a distance D1, and axially to the bearing 4314 at a distance D2. Alternatively, at least a portion of the first shaft through-hole 201 may be positioned axially to the rotor 11 at a distance D2, and axially to the bearing 4211 at a distance D1. In this way, the refrigerant (i.e., lubricating fluid CL) flowing inside the shaft sleeve 212 can directly flow out through the first shaft through-hole 201 positioned axially to the rotor 11 at a distance D1 or axially to the bearing 4211, 4314.

[0062] <1-2-3. Second shaft through hole 202>

[0063] The second shaft through hole 202 is disposed in at least one of the cover portion 22 and the shaft sleeve portion 212. In this embodiment, the second shaft through hole 202 is disposed in the cover portion 22 and extends through the cover portion 22 axially (see, for example, reference). Figure 2 Thus, compared to the case where the second shaft through-hole 202 is disposed on the first shaft 21, air is more easily drawn into the interior of the first shaft 21. Furthermore, if multiple second shaft through-holes 202 that function as air intakes are provided, the amount of air drawn into the first shaft 21 and the flow of the drawn-in airflow can be appropriately adjusted according to the number and configuration of the second shaft through-holes 202.

[0064] Figure 6A This shows a first configuration example of the second shaft through hole 202 in the cover portion 22. Figure 6B This shows a second configuration example of the second shaft through hole 202 in the cover portion 22. Figure 6CThis illustrates a third configuration example of the second shaft through-hole 202 in the cover portion 22. Alternatively, at least a portion of the second shaft through-hole 202 may be radially disposed between the radially outer end of the cover portion 22 and the second shaft 23 (see, for example, reference...). Figure 6A Alternatively, at least a portion of the second shaft through-hole 202 may be configured along the radially outer surface of the second shaft 23 (see, for example, reference). Figure 6B Alternatively, at least a portion of the second shaft through hole 202 may be configured along the radially outer end of the cover portion 22 (see, for example, reference). Figure 6C Furthermore, the second axial through hole 202 disposed along the radially outer end of the cover portion 22 may also be formed by a notch formed at the radially outer end of the cover portion 22 and a notch formed at one end of the axial direction of the first shaft 21.

[0065] However, not limited to the above example, the second shaft through hole 202 can also be disposed on the first shaft 21 and extend through the first shaft 21 radially. Figure 7 This illustrates an example of a second shaft through-hole 202 configured on the first shaft 21. For example... Figure 7 As shown, the second shaft through-hole 202 can also be disposed in the shaft sleeve portion 212 and extend radially through the shaft sleeve portion 212. In this way, a larger amount of air can be drawn into the first shaft 21. Furthermore, if multiple second shaft through-holes 202 that function as air intakes are provided, the amount of air flowing into the first shaft 21 and the flow of the drawn-in airflow can be appropriately adjusted according to the number and arrangement of the second shaft through-holes 202.

[0066] Furthermore, the number of second shaft through holes 202 can be either single or multiple. In the latter case, the second shaft through holes 202 can be arranged at equal or different intervals in the circumferential direction (e.g., see reference). Figures 6A to 6C ).

[0067] <1-2-4. Cover 22>

[0068] Next, refer to Figure 2 , Figures 8 to 11 The cover 22 will be described. Figures 8 to 11 These are the first to fourth variations of the cover 22.

[0069] In this embodiment, such as Figure 2 As shown, the cover portion 22 is plate-shaped and extends radially from the first axis of rotation J1. However, the cover portion 22 is not limited to the example shown above. Figure 8 Other shapes of the cover 22 are indicated. The cover 22 can be any shape other than a plate, or for example, as shown in the diagram. Figure 8 The cone shape shown expands radially outward as it moves toward either axis D1 or axis D2.

[0070] Preferably, the cover 22 is integral with the first shaft 21. Alternatively, the cover 22 is integral with the second shaft 23. For example, in this embodiment, the cover 22 and the second shaft 23 are different parts of the same component (see reference). Figure 2 However, it can also be a different part of the same component as the first shaft 21 (see reference). Figure 9 By making the cover 22 integral with the first shaft 21 or the second shaft 23, it is easier to manufacture the shaft 2. In addition, the number of components of the shaft 2 can be reduced, thus facilitating the assembly of the motor 100. However, the above illustration does not exclude the possibility that the cover 22 and the first shaft 21 and the second shaft 23 are different components.

[0071] Furthermore, when the cover portion 22 and the second shaft 23 are different components, the cover portion 22 may also have a hole portion 221 (see reference). Figure 10 The hole 221 is disposed at one axial end of the cover 22 and extends to the other axial direction D2. Furthermore, the hole 221 can be... Figure 10 The diagram shows a through hole extending axially through the cover portion 22, or a recess extending from one axial end of the cover portion 22 towards the other axial end, D2. The portion of the second shaft 23 on the other axial side, D2, is inserted into the hole portion 221. In this way, the second shaft 23 can be easily installed on the cover portion 22.

[0072] When the second shaft 23 is inserted into the hole 221, the shaft 2 preferably also has a first fixing part 222. The first fixing part 222 fixes the second shaft 23 to the cover part 22 (see reference). Figure 10 The first fixing part 222 can be, for example, brazing filler metal (such as silver solder), adhesive, or a weld mark. That is, the means by which the second shaft 23 is fixed to the cover 22 in the hole 221 can be brazing, bonding with adhesive, or weld. This allows the second shaft 23 to be held more reliably in the cover 22. Furthermore, the first fixing part 222 is not limited to the examples described above. For example, the two can be fixed by screwing together a male threaded portion formed on the radially outer surface of the second shaft 23 with a female threaded portion formed on the inner surface of the hole 221. However, the above examples do not preclude the shaft 2 from having a structure without the first fixing part 222.

[0073] Furthermore, in this embodiment, such as Figure 2 As shown, the cover 22 is connected to one axial end of the shaft sleeve portion 212 and covers the opening at one axial end of the shaft sleeve portion 212. However, the cover 22 is not limited to the example shown above. For example, the cover 22 may be disposed radially beyond the first shaft through hole 201, and disposed on the inner side of the shaft sleeve portion 212 on the axial side D1 (see reference). Figure 11In other words, the cover 22 can also be inserted into one axial end of the first shaft 21. By inserting the cover 22 into the first shaft 21, the second shaft 23 can be mounted on the first shaft 21. Therefore, the axial length of the shaft 2 can be adjusted.

[0074] Furthermore, when the cover 22 is embedded in the first shaft 21, it is preferable, for example, as shown in the example. Figure 11 As shown, shaft 2 also has a second fixing part 223. The second fixing part 223 fixes the cover part 22 to the first shaft 21. The second fixing part 223 can be, for example, brazing filler metal (silver solder, etc.), adhesive, or a weld mark. That is, the means by which the cover part 22 on the axial side D1 inside the shaft sleeve 212 is fixed to the first shaft 21 can be brazing, bonding with adhesive, or weld. In this way, the first shaft 21 can hold the cover part 22 more reliably. In addition, the second fixing part 223 is not limited to the above example. For example, the two can also be fixed by screwing the male thread portion formed on the radially outer side of the second shaft 23 with the female thread portion formed on the inner side of the hole portion 221. However, the above example does not exclude the structure of shaft 2 without the second fixing part 223.

[0075] Furthermore, when the cover portion 22 is embedded in the first shaft 21, the cover portion 22 preferably also has a first chamfered portion 224 (see reference). Figure 11 The first chamfered portion 224 is disposed at the radially outer end of the other axial end of the cover portion 22. For example, at the other axial end of the cover portion 22, a so-called round chamfering, forming a curved surface between the axial end face and the radially outer side face, is applied circumferentially at the corner formed by the other axial end face and the radially outer side face of the cover portion 22, or a so-called beveling, which obliquely cuts off the corner of the aforementioned corner. With the arrangement of the first chamfered portion 224, the cover portion 22 can be more easily inserted into the axial end of the first shaft 21. Therefore, it is easier to install the first shaft 21 and the cover portion 22 at the axial end of the first shaft 21. However, the above illustration does not preclude the cover portion 22 from having a structure with the first chamfered portion 224.

[0076] <1-2-5. Other variations of shaft 2>

[0077] Next, refer to Figures 12 to 14 Other variations of shaft 2 will be explained. Figures 12 to 14 These are the first to third deformation examples of shaft 2, respectively.

[0078] like Figures 12 to 14 As shown, shaft 2 may also have a cylindrical cover portion 24. The cover portion 24 extends from one axial end of cover portion 22 in the opposite axial direction D2. The outer peripheral surface of the cover portion 24 contacts the inner peripheral surface of one axial end of the first shaft 21. For example, the cover portion 24 may also be as follows: Figure 12 As shown, the cover portion 22, which seals one axial end of the shaft sleeve portion 212, extends axially to the other axial direction D2. Furthermore, the cover sleeve portion 24 can also be as follows... Figure 13 As shown, the cover portion 22 extends from one axial direction D1, which is embedded in the shaft sleeve portion 212, to the other axial direction D2. The cover sleeve portion 24 can also be as follows: Figure 14 As shown, for example, a conical cover portion 22 extends radially outward from either axial direction D1 or axial direction D2, extending towards the other axial direction D2. When the cover portion 22 is installed on the first shaft 21, the cover sleeve portion 24 prevents the cover portion 22 from tilting relative to the axial direction, thus improving the installation accuracy of the cover portion 22 and the second shaft 23 relative to the first shaft 21. Therefore, for example, it is possible to suppress or prevent the offset between the rotation center of the second shaft 23 and the rotation center of the first shaft 21. Moreover, when a refrigerant such as lubricating fluid CL flows inside the first shaft 21, the cover sleeve portion 24 prevents the refrigerant flowing along the inner circumferential surface of the first shaft 21 due to the rotation of the shaft 2 from reaching the axial end of the first shaft 21. Therefore, refrigerant is less likely to leak from the axial end of the first shaft 21.

[0079] Preferably, the cover portion 24 has a second chamfered portion 241. The second chamfered portion 241 is disposed at the other axial end of the outer peripheral surface of the cover portion 24 (see reference). Figures 12 to 14 For example, at the other axial end of the cover portion 24, a so-called round chamfering is applied circumferentially at the corner formed by the outer peripheral surface of the cover portion 24 and the other axial end face, forming a curved surface between the two, or a so-called beveling is applied by obliquely cutting off the corner. With the arrangement of the second chamfered portion 241, the cover portion 24 can be easily inserted into one axial end of the first shaft 21. Therefore, the cover portion 22 can be easily installed at one axial end of the first shaft 21. However, the above illustration does not preclude the cover portion 22 from having a structure without the second chamfered portion 241.

[0080] In addition, the first shaft 21 may also have a third chamfered portion 214. The third chamfered portion 214 is disposed at one axial end of the inner circumferential surface of the first shaft 21. The above structure is an example of a structure in which the cover portion 22 is embedded in the first shaft 21 (see, for example, the structure shown). Figure 11 , Figures 13 to 14 Shaft 2 has a structure with a cover sleeve 24 (see, for example, reference). Figure 11 and Figure 14This is particularly effective in applications such as... For example, at one axial end of the first shaft 21, a so-called round chamfering is applied circumferentially to the corner formed by the inner circumferential surface of the first shaft 21 and the axial end face, forming a curved surface between the two, or a so-called beveling is applied by obliquely cutting off the corner. With the arrangement of the third chamfered portion 214, the component can be easily inserted into one axial end of the first shaft 21. For example, the cover portion 22 or the cover sleeve portion 24, described later, can be more easily inserted into one axial end of the first shaft 21 (see the description below). Figures 11 to 14 Therefore, components such as the cover portion 22 and the cover sleeve portion 24 can be easily installed on one axial end of the first shaft 21. However, the above example does not preclude the possibility that the first shaft 21 may not have a structure with a third chamfered portion 214.

[0081] <1-3. Power Transmission Device 3>

[0082] Next, refer to Figure 1 The details of the power transmission device 3 are explained below. The power transmission device 3 transmits the power from the electric motor 1 to the output shaft Ds. The power transmission device 3 includes a reduction gear 31 and a differential gear 32.

[0083] <1-3-1. Speed ​​Reduction Device 31>

[0084] The reduction gear 31 is connected to the shaft 2. The reduction gear 31 has the function of reducing the speed of the motor unit 1 and increasing the torque output from the motor unit 1 according to the reduction ratio. The reduction gear 31 transmits the torque output from the motor unit 1 to the output shaft Ds. That is, the power transmission device 3 is connected to the other side D2 of the shaft 2, which rotates around the first rotation axis J1 extending in the horizontal direction.

[0085] The reduction gear 31 has a main drive gear 311, an intermediate driven gear 312, a final drive gear 313, and an intermediate shaft 314. The torque output from the motor unit 1 is transmitted to the gear ring 321 of the output shaft Ds via the shaft 2, the main drive gear 311, the intermediate driven gear 312, the intermediate shaft 314, and the final drive gear 313.

[0086] The main drive gear 311 is disposed on the outer circumferential surface of the shaft 2. The main drive gear 311 can be the same component as the shaft 2, or it can be a different component and be securely fixed. The main drive gear 311 and the shaft 2 rotate together around the first rotation axis J1.

[0087] The intermediate shaft 314 extends along a second rotation axis J2 parallel to the first rotation axis J1. Both ends of the intermediate shaft 314 are supported by a first intermediate bearing 4231 and a second intermediate bearing 4621, enabling it to rotate about the second rotation axis J2. An intermediate driven gear 312 and a final drive gear 313 are disposed on the outer circumferential surface of the intermediate shaft 314. The intermediate driven gear 312 and the intermediate shaft 314 can be the same component or different components that are securely fixed together.

[0088] The intermediate driven gear 312 and the final drive gear 313 rotate integrally with the intermediate shaft 314 around the second rotation axis J2. The intermediate driven gear 312 meshes with the main drive gear 311. The final drive gear 313 meshes with the gear ring 321 of the output shaft Ds.

[0089] The torque of shaft 2 is transmitted from the main drive gear 311 to the intermediate driven gear 312. Then, the torque transmitted to the intermediate driven gear 312 is transmitted to the final drive gear 313 via the intermediate shaft 314. Finally, the torque is transmitted from the final drive gear 313 to the output shaft Ds.

[0090] <1-3-2. Differential Device 32>

[0091] A differential device 32 is mounted on the output shaft Ds. The differential device 32 has a gear ring 321. The gear ring 321 transmits the output torque of the motor unit 1 to the output shaft Ds. The output shaft Ds has axles Ds1 and Ds2 respectively mounted on the left and right sides of the differential device 32. For example, when the vehicle is turning, the differential device 32 absorbs the difference in rotational speed between the left and right axles and transmits torque to the left and right axles Ds1 and Ds2.

[0092] The lower end of the gear ring 321 is disposed inside the liquid storage section P, which is described later. The liquid storage section P is for storing lubricating fluid CL and the like stored in the lower part of the gear section receiving space 402 (see reference). Figure 1 Therefore, when the gear ring 321 rotates, the lubricating fluid CL is lifted up by the gear teeth of the gear ring 321. The lubricating fluid CL lifted up by the gear ring 321 lubricates or cools the gears and bearings of the power transmission device 3. In addition, a portion of the lifted lubricating fluid CL is stored in the receiving tray 464 (described later) and is also used for cooling the motor unit 1 via the shaft 2.

[0093] <1-4. Outer Shell 4>

[0094] Next, refer to Figure 1 and Figure 2The details of the outer casing 4 will be described below. The outer casing 4 includes a first outer casing cylindrical portion 41, a side plate portion 42, a motor cover portion 43, a cover member 44, a second outer casing cylindrical portion 45, and a gear cover portion 46. Furthermore, the first outer casing cylindrical portion 41, the side plate portion 42, the motor cover portion 43, the second outer casing cylindrical portion 45, and the gear cover portion 46 are formed, for example, using conductive materials; in this embodiment, they are formed using metallic materials such as iron, aluminum, and their alloys. Moreover, to suppress contact corrosion between different types of metals at the contact portions, it is preferable that the above components are formed using the same material. However, this is not limited to the above example; the above components may be formed using materials other than metallic materials, or at least a portion of the above components may be formed using different materials.

[0095] Furthermore, as mentioned above, the outer casing 4 houses the rotor 11, stator 12, and bearings 4211 and 4314 of the motor unit 1. Specifically, the outer casing 4 has a motor housing space 401. The motor housing space 401 is a space enclosed by the first outer casing cylindrical portion 41, the side plate portion 42, and the motor cover portion 43, which houses the rotor 11, stator 12, and bearings 4211 and 4314.

[0096] Furthermore, the outer casing 4 houses the power transmission device 3. Specifically, the outer casing 4 has a gear storage space 402. The gear storage space 402 is a space enclosed by the side plate portion 42, the second outer casing cylinder portion 45, and the gear cover portion 46, which houses the reduction gear 31 and the differential device 32, etc.

[0097] A liquid reservoir P for storing lubricating fluid CL is disposed in the lower part of the gear housing space 402. A portion of the differential device 32 is immersed in the liquid reservoir P. The lubricating fluid CL stored in the liquid reservoir P is lifted by the operation of the differential device 32 and supplied to the interior of the gear housing space 402. For example, the lubricating fluid CL is lifted by the tooth surface of the gear ring 321 when the gear ring 321 of the differential device 32 rotates. A portion of the lifted lubricating fluid CL is supplied to the gears and bearings of the reduction gear 31 and the differential device 32 in the gear housing space 402 for lubrication. In addition, another portion of the lifted lubricating fluid CL is supplied to the interior of the shaft 2, and to the rotor 11 and stator 12 of the motor unit 1, and the bearings in the gear housing space 402 for cooling and lubrication.

[0098] <1-4-1. First outer casing cylindrical section 41>

[0099] The first outer casing cylindrical portion 41 is cylindrical in shape, extending axially. The motor portion 1 and the motor oil reservoir 64 (described later) are disposed inside the first outer casing cylindrical portion 41. Furthermore, the stator core portion 121 is fixed to the inner surface of the first outer casing cylindrical portion 41.

[0100] <1-4-2. Side panel 42>

[0101] The side plate portion 42 extends in a direction perpendicular to the first axis of rotation J1 and covers the other axial end of the first outer casing portion 41. In this embodiment, the first outer casing portion 41 and the side plate portion 42 are different parts of a single component. By forming them as one piece, their rigidity can be improved. However, not limited to the above example, the first outer casing portion 41 and the side plate portion 42 may also be different components.

[0102] The side plate portion 42 has: a side plate through hole 4201 for inserting shaft 2; and a first output shaft through hole 4202. The side plate through hole 4201 and the first output shaft through hole 4202 extend axially through the side plate portion 42. A first shaft 21 is inserted into the side plate through hole 4201. An axle Ds1 of the output shaft Ds is inserted into the first output shaft through hole 4202. An oil seal (not shown) is disposed in the gap between the output shaft Ds and the first output shaft through hole 4202 to seal the two. In addition, the term "sealing" means that different components are in close contact with each other to such an extent that the lubricating fluid CL inside the components will not leak to the outside, and foreign objects such as water, dust, and dirt from the outside will not enter. The same applies to the sealing.

[0103] In addition, the side plate portion 42 also has bearing retaining portions 421, 422, 423, and 424. Bearing retaining portion 421 is disposed on one axial end face of the side plate portion 42 in the motor housing space 401 and retains bearing 4211. Bearing retaining portions 422, 423, and 424 are disposed on the other axial end face of the side plate portion 42 in the gear housing space 402 (described later). Bearing retaining portion 422 is disposed along the outer edge of the other axial end of the side plate through hole 4201 and retains bearing 4211. Bearing retaining portion 423 retains the first intermediate bearing 4231. Bearing retaining portion 424 is disposed along the outer edge of the other axial end of the first output shaft through hole 4202 and retains the first output bearing 4241.

[0104] <1-4-3. Motor cover 43>

[0105] The motor cover 43 is mounted on one axial end of the first housing cylinder 41. The motor cover 43 can be fixed to the first housing cylinder 41, for example, by screws, but is not limited to this; methods such as screwing or pressing can also be widely used to securely fix the cover 433 to the first housing cylinder 41. Thus, the motor cover 43 can fit tightly against one axial end of the first housing cylinder 41. Furthermore, "tightly fitted" means having a degree of sealing such that the lubricating fluid CL inside the component will not leak to the outside, and external foreign matter such as water, dust, and dirt will not enter. The same applies to the following regarding tightness.

[0106] like Figure 2 As shown, the motor cover 43 has a cover 431, a cylindrical part 432, a plate part 433, and a bearing retainer 434. In other words, the housing 4 has a cover 431, a cylindrical part 432, and a plate part 433.

[0107] <1-4-3-1. Cover 431>

[0108] The cover portion 431 extends in a direction intersecting the first rotation axis J1 and covers one axial end of the first outer casing portion 41. The cover portion 431 has an opening 4311 through which the shaft 21 is inserted. The opening 4311 extends axially through the cover portion 431. The first shaft 21 is inserted into the opening 4311. In addition, the cover portion 431 also has a bearing retaining portion 4312 and a sealing member 4313. The bearing retaining portion 4312 is disposed on the other axial end face of the cover portion 431 in the motor housing space 401. The bearing retaining portion 4312 is disposed along the outer edge of the other axial end of the opening 4311 and retains the bearing 4314. The sealing member 4313 is disposed between the first shaft 21 in the opening 4311 and the cover portion 431 and seals the two. By sealing the opening 4311 with the sealing member 4313, it is possible to prevent, for example, foreign matter such as wear powder generated in the electrostatic eliminator 7 from entering the motor storage space 401 containing the stator 12 through the opening 4311.

[0109] <1-4-3-2. Cylindrical section 432>

[0110] The cylindrical portion 432 is cylindrical in shape, surrounding the first rotation axis J1, and extends from one axial end of the cover portion 431 to one axial end D1.

[0111] <1-4-3-3. Plate Part 433>

[0112] Plate portion 433 extends in a direction intersecting the first rotation axis J1 and is mounted at one axial end of cylindrical portion 432. Plate portion 433 is conductive. As previously described, housing 4 has plate portion 433. In this embodiment, plate portion 433 is disposed axially towards one side D1 from stator 12 and bearing 4341 (described later) and extends radially. An opening 4331 for insertion of second shaft 23 is provided in plate portion 433. In other words, plate portion 433 has opening 4331. Opening 4331 extends axially through plate portion 433. Furthermore, a current-eliminating device 7 is disposed at one axial end of plate portion 433.

[0113] <1-4-3-4. Bearing Retention Part 434>

[0114] The bearing retainer 434 is disposed in the other axial end face of the plate portion 433 along the outer edge of one axial end of the opening portion 4331, and retains the bearing 4341.

[0115] <1-4-3-5. Sealing component 435>

[0116] A sealing member 435 is disposed in the opening 4331 of the plate portion 433. The motor 100 includes an annular sealing member 435. The sealing member 435 is disposed between the second shaft 23 in the opening 4331 and the plate portion 433, and seals the space between them. The radially outer end of the sealing member 435 contacts the radially inward-facing inner circumferential surface of the opening 4331. The radially inner end of the sealing member 435 contacts the radially outer surface of the second shaft 23. By sealing the opening 4331 with the sealing member 435, wear powder generated from the de-energizing device 7 disposed on one axial end face of the plate portion 433 can be prevented from entering the other axial side of the plate portion 433 through the opening 4331. Therefore, wear powder can be prevented from entering the interior of the housing 4 containing the stator 12, etc. For example, wear powder can also be prevented from entering the hollow portion 211 of the first shaft 21 through the second shaft through hole 202. Therefore, wear powder can be prevented from entering the motor housing space 401 along with the lubricant CL in the hollow part 211.

[0117] <1-4-4. Cover Component 44>

[0118] The cover member 44 is disposed on one end face of the plate portion 433 along the axial direction. The cover member 44 covers the opening portion 4331 and the electrostatic removal device 7.

[0119] The mounting of the cover member 44 to the plate portion 433 can be, for example, by threaded fastening, but is not limited to this. In this embodiment, the cover member 44 and the plate portion 433 together form a storage space 440. The storage space 440 is the space enclosed by the cover member 44 and the plate portion 433, and houses the opening 4331 and the power removal device 7.

[0120] The cover member 44 has a first cover portion 441 and a second cover portion 442. The first cover portion 441 covers the current-eliminating device 7. The second cover portion 442 is disposed radially outward from the first cover portion 441. Specifically, the first cover portion 441 and the second cover portion 442 extend in a direction intersecting the first rotation axis J1. The first cover portion 441 is disposed axially to one side D1 from the opening portion 4331 and the current-eliminating device 7. Furthermore, the second cover portion 442 is disposed axially to the other side D2 from the first cover portion 441. The radially inner end portion of the second cover portion 442 is connected to the radially outer end portion of the first cover portion 441, and the radially outer end portion of the second cover portion 442 is connected to one axial end face of the plate portion 443.

[0121] Furthermore, the cover component 44 has a through hole 443, a cylindrical portion 444, and a filter 445. The through hole 443 communicates with the reception space 440 and its exterior. The through hole 443... Figure 1 It is disposed in the first cover portion 441. However, the configuration of the through hole 443 is not limited to... Figure 1 Example. A through-hole 443 can be disposed in at least one of the first cover portion 441 and the second cover portion 442. A cylindrical portion 444 extends axially from the outer edge of the through-hole 443. The interior of the cylindrical portion 444 communicates with the through-hole 443. A filter 445 is mounted on the front end of the cylindrical portion 444. A receiving space 440 communicates with the outside via the through-hole 443 and the filter 445.

[0122] <1-4-5. Second outer casing section 45>

[0123] The second outer casing cylindrical portion 45 is cylindrical in shape, extending axially. A power transmission device 3 is disposed inside the second outer casing cylindrical portion 45. One axial end of the second outer casing cylindrical portion 45 is connected to and covered by the side plate portion 42.

[0124] <1-4-6. Gear cover 46>

[0125] The gear cover portion 46 extends in a direction intersecting the first rotation axis J1 and is detachably mounted to the other axial end of the second housing cylinder portion 45. In this embodiment, the second housing cylinder portion 45 and the gear cover portion 46 are separate parts of a single component. However, not limited to the above example, the second housing cylinder portion 45 and the gear cover portion 46 may also be different components. Furthermore, the mounting of the gear cover portion 46 to the second housing cylinder portion 45 can be, for example, secured with screws, but is not limited to this; methods such as screwing in or pressing in can also be widely used to securely fix the gear cover portion 46 to the second housing cylinder portion 45. Thus, the gear cover portion 46 can be tightly fitted to the other axial end of the second housing cylinder portion 45.

[0126] The gear cover portion 46 has a second output shaft through hole 460. The center of the second output shaft through hole 460 coincides with the third rotation axis J3. An output shaft Ds is inserted through the second output shaft through hole 460. An oil seal (not shown) is disposed in the gap between the other output shaft Ds and the second output shaft through hole 460.

[0127] Furthermore, the gear cover portion 46 also has bearing retaining portions 461, 462, and 463. The bearing retaining portions 461, 462, and 463 are disposed on one axial end face of the gear cover portion 46 within the gear receiving space 402. The bearing retaining portion 461 holds the bearing 4611. The bearing retaining portion 462 holds the second intermediate bearing 4621. The bearing retaining portion 463 is disposed along the outer edge of one axial end of the second output shaft through hole 460 and holds the second output bearing 4631.

[0128] Furthermore, the gear cover portion 46 includes a receiving disc portion 464 and an oil passage 465. The receiving disc portion 464 is disposed on one axial end face of the gear cover portion 46 and has a recessed portion that is recessed vertically downward. Lubricating fluid CL that can be lifted by the gear ring 321 is stored in the receiving disc portion 464. The oil passage 465 is a passage for the lubricating fluid CL, which connects the receiving disc portion 464 to the inlet 213 of the shaft 2. The lubricating fluid CL stored in the receiving disc portion 464 is supplied to the oil passage 465 and flows into the hollow portion 211 from the inlet 213 at the other axial end of the shaft 2.

[0129] <1-5. Liquid Circulation Section 6>

[0130] Next, the liquid circulation unit 6 will be described. The liquid circulation unit 6 includes a piping unit 61, a pump 62, an oil cooler 63, and an electric motor oil storage unit 64.

[0131] The piping section 61 connects the pump 62 to the electric motor oil reservoir 64 disposed inside the first housing cylinder section 41, and supplies lubricant CL to the electric motor oil reservoir 64. The pump 62 draws in the lubricant CL stored in the lower region of the gear section receiving space 402. The pump 62 is an electric pump, but is not limited to this. For example, it may be configured to be driven by a portion of the power of the shaft 2 of the electric motor 100.

[0132] An oil cooler 63 is disposed between the pump 62 and the motor oil reservoir 64 in the piping section 61. That is, the lubricating fluid CL drawn by the pump 62 passes through the oil cooler 63 via the piping section 61 and is then delivered to the motor oil reservoir 64. For example, refrigerant such as water supplied from an external source is supplied to the oil cooler 63. The oil cooler 63 performs heat exchange between the refrigerant and the lubricating fluid CL to lower the temperature of the lubricating fluid CL.

[0133] The motor oil reservoir 64 is a tray located vertically above the stator 12 inside the motor housing 401. A drip hole is formed at the bottom of the motor oil reservoir 64, through which lubricating fluid CL is dripped to cool the motor section 1. The drip hole is formed, for example, on the upper part of the coil edge 1221 of the coil 122 of the stator 12, and the coil 122 is cooled by the lubricating fluid CL.

[0134] <2. Other>

[0135] The embodiments of the present invention have been described above. However, the scope of the present invention is not limited to the above embodiments. Various modifications can be made to the above embodiments and implemented without departing from the spirit of the invention. Furthermore, the matters described in the above embodiments can be appropriately combined arbitrarily without causing contradictions.

[0136] Industrial availability

[0137] This invention is useful in devices for grounding shafts.

Claims

1. An electric motor, comprising: A shaft having a first, cylindrical shaft extending axially; A rotor, which is supported by the first shaft and can rotate with the shaft; The stator is arranged radially outward from the rotor; The bearing supports the first shaft so that it can rotate; A housing that houses the rotor, the stator, and the bearings; and The current-eliminating device electrically connects the shaft to the housing. The shaft also has: A cover portion, the cover portion being disposed at one axial end of the first shaft; A second shaft extends axially from the cover portion; A first shaft through hole extends radially through the first shaft; as well as The second shaft through hole communicates with both the interior and exterior spaces of the first shaft. The cover and the second shaft are electrically conductive. The second shaft through hole is positioned axially closer to the first shaft through hole. The second shaft is in contact with the electrostatic removal device. The cover has a hole located at one axial end of the cover and extending axially to the other. The second shaft is a component different from the cover. The portion of the second shaft on the other axial side is embedded into the hole.

2. The electric motor as claimed in claim 1, wherein, The shaft also has a first fixing part, which fixes the second shaft to the cover.

3. The electric motor as described in claim 1 or 2, wherein, The cover is embedded into one axial end of the first shaft.

4. The electric motor as described in claim 1 or 2, wherein, The shaft also has a cylindrical cover portion that extends axially from one end of the cover portion to the other end. The outer peripheral surface of the cover cylinder contacts the inner peripheral surface of one axial end of the first shaft.

5. The electric motor as described in claim 4, wherein, The cover portion has a second chamfered portion. The second chamfered portion is disposed at the other axial end of the outer peripheral surface of the cover cylinder.

6. The electric motor as claimed in claim 1 or 2, wherein, The first shaft also has a third chamfered portion. The third chamfered portion is disposed at one axial end of the inner circumferential surface of the first shaft.

7. The electric motor as claimed in claim 1 or 2, wherein, It also includes annular sealing components. The housing has a plate portion disposed axially relative to the bearing and extending radially. The plate portion is provided with an opening for the second shaft to pass through. The sealing member is disposed at the opening of the plate. The current-eliminating device is disposed at one axial end of the plate portion. The outer radial end of the sealing member contacts the inner circumferential surface of the opening facing radially inward. The radial inner end of the sealing member contacts the radial outer side of the second shaft.

8. The electric motor as claimed in claim 1 or 2, wherein, It also includes refrigerant flowing inside the first shaft.

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