In-wheel motor

Abstract

To restrain oil leakage due to hydraulic pressure that is generated in an oil pump.SOLUTION: An in-wheel motor includes a case having a motor case, a motor cover and a speed reducer case. An oil pump includes: a pump chamber formed in the motor cove; a pump cover attached to the motor cover and blocking the pump chamber; a pump shaft provided through the pump cover; a drive gear attached to the pump shaft and arranged inside the pump chamber; and a driven gear meshed with the drive gear and arranged inside the pump chamber. The pump shaft is installed to an input shaft of the speed reducer. The pump cover is fastened by a bolt to the motor cover from the inside of the case, with a positioning structure for positioning the pump shaft being integrally formed with the pump cover.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an in-wheel motor. [Background technology]

[0002] Patent document 1 discloses a structure in which an in-wheel motor comprises a case including a motor cover consisting of a first cover member and a second cover member, and an oil pump provided within the case, and an oil passage formed between the first cover member and the second cover member is connected to the oil pump. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-138340 Summary of the Invention [Problem to be solved by the invention]

[0004] In the configuration described in Patent Document 1, when the first cover member and the second cover member that form the oil passage are integrated, it is necessary to fasten the second cover member to the first cover member by screwing bolts into the first cover member and then the second cover member from the outside of the case. That is, this bolt fastening portion includes a bolt hole that opens to the outside of the case and is provided in the first motor cover. Therefore, when oil is pumped into the oil passage by the oil pump, there is a risk of oil leaking to the outside of the case through the bolt fastening portion.

[0005] The present invention has been made in view of the above circumstances, and has an object to provide an in-wheel motor that can suppress oil leakage due to hydraulic pressure generated in an oil pump. [Means for solving the problem]

[0006] The present invention is an in-wheel motor comprising: a motor arranged inside a wheel; a reducer having an input shaft attached to a rotor shaft of the motor and transmitting power of the motor to the wheel; a case accommodating the motor and the reducer; and an oil pump arranged inside the case, wherein the case has a motor case accommodating the motor, a motor cover attached to the motor case, and a reducer case attached to the motor case on the opposite side of the motor cover and accommodating the reducer, wherein the oil pump has a pump chamber formed in the motor cover, a pump cover attached to the motor cover and closing the pump chamber, a pump shaft extending through the pump cover, a drive gear attached to the pump shaft and arranged inside the pump chamber, and a driven gear meshing with the drive gear and arranged inside the pump chamber, wherein the pump shaft is attached to the input shaft of the reducer, the pump cover is bolted to the motor cover from the inside of the case, and the pump cover is integrally formed with a positioning structure for determining the position of the pump shaft.

[0007] With this configuration, when attaching the pump cover to the motor cover, it is sufficient to fasten the bolts from the inside of the case, eliminating the need to fasten the bolts from the outside of the case, thereby suppressing oil leakage due to hydraulic pressure generated in the oil pump.

[0008] The positioning structure may have a boss portion through which the pump shaft is inserted, and may support the pump shaft via a bearing attached to an inner peripheral surface of the boss portion.

[0009] According to this configuration, the pump shaft can be supported by the positioning structure of the pump cover.

[0010] The motor cover may also be cylindrical, protrude axially toward the inside of the case, have a housing portion for housing the pump cover, and further include a bearing attached to the inside of the housing portion for rotatably supporting the rotor shaft, and a resolver attached to the outside of the housing portion for detecting the rotation speed of the rotor shaft.

[0011] With this configuration, the pump cover and bearings are placed inside the housing of the motor cover, and then the resolver is attached to the outside of that housing, making it easier to route the resolver's wire harness outside the motor cover. [Effects of the Invention]

[0012] In this invention, when attaching the pump cover to the motor cover, it is sufficient to fasten the bolts from the inside of the case, eliminating the need to fasten the bolts from the outside of the case, which makes it possible to suppress oil leakage due to hydraulic pressure generated in the oil pump. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a diagram showing an in-wheel motor according to an embodiment; [Figure 2] FIG. 2 is a diagram illustrating an oil pump. [Figure 3] FIG. [Figure 4] FIG. 4 is a diagram showing a drive gear of the oil pump. [Figure 5] FIG. 4 is a diagram showing a driven gear of the oil pump. [Figure 6] 10A and 10B are views showing a housing portion and a pump chamber formed in a motor cover. [Figure 7] FIG. [Figure 8] 10 is a diagram showing a state in which a bearing and a resolver are attached to an accommodating portion. FIG. [Figure 9] 10A and 10B are diagrams for explaining an assembly method when assembling a pump shaft. [Figure 10]10A and 10B are diagrams for explaining an assembly method when assembling a gear shaft. [Figure 11] 10A and 10B are diagrams for explaining a process of matching the phases of a pump shaft and a gear shaft. [Figure 12] FIG. 10 is a diagram showing a state in which a gear shaft is assembled. DETAILED DESCRIPTION OF THE INVENTION

[0014] An in-wheel motor according to an embodiment of the present invention will be specifically described below, although the present invention is not limited to the embodiment described below.

[0015] FIG. 1 is a diagram showing an in-wheel motor according to an embodiment. The in-wheel motor 1 is arranged inside the wheel of a vehicle. The in-wheel motor 1 includes a motor 2 that drives the wheel and a reducer 3 that transmits the power of the motor 2 to the wheel. The reducer 3 reduces the rotation of the motor 2 and outputs it. In the in-wheel motor 1, the power output from the motor 2 is transmitted to the wheel via the reducer 3. In this description, the axial direction is the same as the width direction of the vehicle. The outer side in the width direction of the vehicle is referred to as one side in the axial direction, and the inner side in the width direction of the vehicle is referred to as the other side in the axial direction.

[0016] The in-wheel motor 1 includes a case 4 that houses a motor 2 and a reducer 3. The case 4 is connected to the lower arm and is supported on the vehicle body via a suspension. The case 4 includes a motor case 11 that houses the motor 2, a reducer case 12 that houses the reducer 3, and a motor cover 13 attached to the motor case 11. The reducer case 12 is attached to the motor case 11 on the side opposite to the motor cover 13. The case 4 has a structure in which the reducer case 12 is bolted to the motor case 11 on one axial side, and the motor cover 13 is bolted to the motor case 11 on the other axial side.

[0017] The motor 2 has a rotor 2a, a stator 2b, and a rotor shaft 2c. The rotor 2a, the stator 2b, and the rotor shaft 2c are arranged inside the motor case 11 and the motor cover 13. The rotor 2a is attached to the rotor shaft 2c so as to rotate integrally with the rotor shaft 2c. The stator 2b is fixed to the inner wall of the motor case 11. The stator 2b is configured to include a stator core and a stator coil wound around the stator core. The motor 2 is a three-phase motor that is electrically connected to a power supply device provided in the vehicle body and generates torque using power supplied from the power supply device. The motor 2 also functions as a generator that generates electricity when the rotor 2a is rotated by the power (torque) of the wheels and regenerates the generated power to the power supply device. The motor 2 is connected to a reducer 3 so as to be able to transmit power.

[0018] The rotor 2a is connected to the gear shaft 3a via the rotor shaft 2c so as to rotate integrally with it. The rotor shaft 2c is a rotating shaft that functions as the output shaft of the motor 2 and is rotatably supported relative to the case 4 by a first bearing 21 and a second bearing 22. The rotor shaft 2c is rotatably supported relative to the motor case 11 via the first bearing 21, and rotatably supported relative to the motor cover 13 via the second bearing 22. The first bearing 21 is a rolling bearing and has an inner ring attached to one end of the rotor shaft 2c, an outer ring attached to the motor case 11, and rolling elements. The second bearing 22 is a rolling bearing and has an inner ring attached to the other end of the rotor shaft 2c, an outer ring attached to the motor cover 13, and rolling elements.

[0019] The rotor shaft 2c is a hollow shaft, and its inner periphery is spline-fitted with the gear shaft 3a. An internal spline is formed at one end of the rotor shaft 2c. An external spline is formed at the other end of the gear shaft 3a. The internal spline of the rotor shaft 2c meshes with the external spline of the gear shaft 3a, thereby spline-fitting the rotor shaft 2c and the gear shaft 3a.

[0020] The gear shaft 3a extends so as to protrude from the inside of the motor case 11, and the protruding portion is housed inside the reducer case 12. The gear shaft 3a is a rotating shaft that functions as the input shaft of the reducer 3, and is rotatably supported relative to the case 4 by a third bearing 23 and a fourth bearing 24. The gear shaft 3a is rotatably supported relative to the motor case 11 via the third bearing 23, and is rotatably supported relative to the reducer case 12 via the fourth bearing 24. The third bearing 23 is a rolling bearing and has an inner ring attached to the other end of the gear shaft 3a, an outer ring attached to the motor case 11, and rolling elements. The fourth bearing 24 is a rolling bearing and has an inner ring attached to one end of the gear shaft 3a, an outer ring attached to the reducer case 12, and rolling elements.

[0021] The reducer 3 is a parallel-axis gear mechanism and has a small-diameter drive gear 3b that rotates integrally with the gear shaft 3a, and a large-diameter driven gear 3c that meshes with the drive gear 3b. The drive gear 3b and driven gear 3c are arranged inside the motor case 11. The drive gear 3b is a gear that outputs the power of the motor 2 to the wheels. The drive gear 3b is a pinion gear molded integrally with the gear shaft 3a and is composed of a helical gear. The driven gear 3c is an external gear that meshes with the drive gear 3b and is also composed of a helical gear. The driven gear 3c is arranged coaxially with the output shaft 3d and rotates integrally with the output shaft 3d. The gear shaft 3a and the output shaft 3d are arranged in parallel.

[0022] The driven gear 3c is rotatably supported relative to the case 4 by a fifth bearing 25 and a sixth bearing 26. The driven gear 3c is rotatably supported relative to the motor case 11 via the fifth bearing 25, and is rotatably supported relative to the reducer case 12 via the sixth bearing 26. The fifth bearing 25 is a rolling bearing and has an inner ring attached to the motor case 11, an outer ring attached to the inner periphery of the driven gear 3c, and rolling elements. The sixth bearing 26 is a rolling bearing and has an inner ring attached to the reducer case 12, an outer ring attached to the inner periphery of the driven gear 3c, and rolling elements.

[0023] The driven gear 3c has a boss on its inner periphery, and the inner periphery of the boss is spline-fitted with the output shaft 3d. An internal spline is formed on the inner periphery of the boss of the driven gear 3c. An external spline is formed on the other end of the output shaft 3d. The internal spline of the driven gear 3c meshes with the external spline of the output shaft 3d, thereby spline-fitting the driven gear 3c and the output shaft 3d.

[0024] The output shaft 3d is a rotating shaft that functions as the output shaft of the reducer 3 and rotates integrally with the wheel. The output shaft 3d is rotatably supported by the reducer case 12 via a hub bearing 5.

[0025] The hub bearing 5 has an inner ring, rolling elements, and an outer ring, and the outer ring is fixed to the reducer case 12. The inner ring of the hub bearing 5 is formed by the cylindrical portion of the axle hub 6.

[0026] The axle hub 6 is rotatably supported relative to the reducer case 12 via a hub bearing 5. The axle hub 6 is attached to the disc portion of the wheel and rotates integrally with the wheel. The axle hub 6 is connected to the output shaft 3d outside the reducer case 12 so as to rotate integrally with the output shaft 3d. A brake disc is also fixed to the axle hub 6. The axle hub 6 and the brake disc are fixed to the disc portion of the wheel by bolts. The output shaft 3d, axle hub 6, brake disc and wheel rotate integrally.

[0027] The in-wheel motor 1 also includes an oil pump 7 provided inside the case 4. The case 4 contains oil for cooling the motor 2. The oil pump 7 pumps oil into oil passages inside the case 4 and supplies the oil to the stator 2b. The stator 2b is a part that requires cooling with oil. Inside the motor case 11, oil accumulates in the lower part of the motor case 11, so the oil is sucked in by the oil pump 7 and pumped through the oil passages to the upper part of the motor case 11.

[0028] The motor cover 13 is formed with an intake oil passage 41 that communicates with the intake port of the oil pump 7, and a discharge oil passage 42 that communicates with the discharge port of the oil pump 7. The intake oil passage 41 communicates between the intake port of the oil pump 7 and an inlet that opens into an oil reservoir at the bottom of the motor case 11. The discharge oil passage 42 communicates between a supply port at the top of the motor case 11 and the discharge port of the oil pump 7. This allows oil pressure-fed by the oil pump 7 to be supplied to a portion of the stator 2b that is located above the rotor 2a. Both the intake oil passage 41 and the discharge oil passage 42 are oil passages formed inside the wall of the motor cover 13. The oil pump 7 draws oil that accumulates in the oil reservoir at the bottom of the motor case 11 through the intake oil passage 41 and discharges it to the discharge oil passage 42. This causes the oil to be pressure-fed to the discharge oil passage 42.

[0029] As shown in FIG. 2, the oil pump 7 includes a pump chamber 31, a drive gear 32, a driven gear 33, a pump cover 34, and a pump shaft 35.

[0030] As shown in Figure 3, the pump chamber 31 is formed on the inner wall of the motor cover 13. The pump chamber 31 is recessed and formed in a concave shape on the other axial end side of the inner wall of the motor cover 13. The motor cover 13 serves as the pump body of the oil pump 7. The pump chamber 31 is formed on the central rotation axis of the rotor shaft 2c and the gear shaft 3a. A drive gear 32 and a driven gear 33 are arranged inside the pump chamber 31.

[0031] The drive gear 32 is configured with an inner rotor as shown in Figure 4. The driven gear 33 is configured with an outer rotor as shown in Figure 5. The driven gear 33 meshes with the drive gear 32.

[0032] The pump cover 34 is attached to the motor cover 13 and closes the pump chamber 31. The oil pump 7 has a structure in which the pump cover 34 is attached to the motor cover 13 so that the drive gear 32 and the driven gear 33 cannot be removed from the pump chamber 31 formed in the motor cover 13. In the oil pump 7, the pump cover 34 is fastened from the inside of the case 4 using bolts. These bolts are screwed into the pump cover 34 and then the motor cover 13 from the inside of the case 4.

[0033] As shown in FIG. 6, the motor cover 13 has bolt holes 13a. The bolt holes 13a are holes recessed from the inner wall surface of the motor cover 13 toward the other axial side. The bolt holes 13a do not pass through the motor cover 13. As shown in FIG. 7, the pump cover 34 has bolt holes 34a. The bolt holes 34a are through-holes that pass through the pump cover 34. Bolts are threaded into the bolt holes 34a of the pump cover 34 and then into the bolt holes 13a of the motor cover 13, to fasten the pump cover 34 to the motor cover 13 from inside the case 4.

[0034] Further, a housing portion 40 is formed in the motor cover 13. As shown in FIG. 2, the housing portion 40 is a portion that houses the pump cover 34, and is formed by the inner wall of the motor cover 13. The pump cover 34 is disposed inside the housing portion 40.

[0035] The accommodation portion 40 is formed in a cylindrical shape and protrudes axially toward the inside of the case 4. The second bearing 22 is attached to the inside of the accommodation portion 40. The outer ring of the second bearing 22 is attached to the inner circumferential surface of the accommodation portion 40. The accommodation portion 40 supports the rotor shaft 2c via the second bearing 22. Inside the accommodation portion 40, the pump cover 34 and the second bearing 22 are arranged side by side in the axial direction.

[0036] The pump shaft 35 is a rotary shaft that rotates integrally with the drive gear 32. The pump shaft 35 is provided to pass through the pump cover 34.

[0037] A positioning structure that determines the position of the pump shaft 35 is integrally molded with the pump cover 34. The positioning structure has a boss portion 34b through which the pump shaft 35 is inserted. This positioning structure supports the pump shaft 35 via a bearing 36 attached to the inner circumferential surface of the boss portion 34b. The bearing 36 is a sliding bearing, and its inner circumferential surface contacts the pump shaft 35 and its outer circumferential surface contacts the boss portion 34b.

[0038] The pump shaft 35 extends inside the rotor shaft 2c and is attached to the gear shaft 3a. The pump shaft 35 is spline-fitted with the gear shaft 3a. An external spline is formed at one end of the pump shaft 35. An internal spline is formed at the other end of the gear shaft 3a. The external spline of the pump shaft 35 meshes with the internal spline of the gear shaft 3a, thereby spline-fitting the pump shaft 35 and the gear shaft 3a.

[0039] The pump shaft 35 rotates integrally with the gear shaft 3a and the rotor shaft 2c. The in-wheel motor 1 includes the pump shaft 35, which serves as the drive shaft of the oil pump 7 and meshes with the drive gear 32. As shown in FIG. 4, a through hole 32a having a two-face width is formed on the inner diameter side of the drive gear 32. The through hole 32a of the drive gear 32 meshes with the other end of the pump shaft 35. The other end of the pump shaft 35 has an outer circumferential portion having a two-face width. The through hole 32a of the drive gear 32 meshes with the outer circumferential portion of the pump shaft 35, connecting the drive gear 32 and the pump shaft 35 so that they can rotate integrally. The pump shaft 35 is driven by the rotation of the rotor shaft 2c of the motor 2 via the gear shaft 3a of the reducer 3.

[0040] Here, we will explain the method of assembling the oil pump 7. The process of assembling the oil pump 7 can be divided into a first half process, which is included in the process of assembling the cover sub-assembly 100, and a second half process, which occurs after the cover sub-assembly 110 is assembled to the motor case sub-assembly 200. In the first half process, assembly up to the pump cover 34 is completed, and in the second half process, assembly of the pump shaft 35 is completed.

[0041] First, the first half of the process will be described, which includes steps 1 to 5.

[0042] In the first step of the first half of the process, the drive gear 32 and the driven gear 33 are assembled to the motor cover 13 so that they fit inside the pump chamber 31. Thereafter, the pump cover 34, which is placed inside the housing portion 40, is fastened to the motor cover 13 so as to close the pump chamber 31.

[0043] In the second step of the first half of the process, the second bearing 22 is attached to the motor cover 13. Then, the resolver 51 is attached to the motor cover 13. The resolver 51 detects the rotation speed of the rotor shaft 2c. More specifically, the second bearing 22 is attached to the inside of the accommodating portion 40. Then, the resolver 51 is attached to the outside of the accommodating portion 40. The resolver 51 is bolted to the outer portion of the accommodating portion 40, as shown in FIG. 8. The state after the second step is completed is shown in FIG. 8.

[0044] In the third step of the first half of the process, the wire harness of the resolver 51 is routed outside the motor cover 13 to form the cover sub-assembly 100. The cover sub-assembly 100 includes the motor cover 13, the drive gear 32, the driven gear 33, the pump cover 34, the second bearing 22, and the resolver 51. Steps 1 to 3 are the steps for assembling the cover sub-assembly 100.

[0045] In the fourth step of the first half of the process, the first bearing 21, rotor 2a, rotor shaft 2c, and stator 2b are assembled to the motor case 11 to form the motor case sub-assembly 200. The motor case sub-assembly 200 includes the motor case 11, the motor 2, and the first bearing 21. The fourth step is the step of assembling the motor case sub-assembly 200.

[0046] In the fifth step of the first half of the process, the cover sub-assembly 100 is attached to the motor case sub-assembly 200. When the fifth step is completed, the first half of the process is completed.

[0047] Next, the latter half of the process will be described with reference to Figures 9 to 12. The latter half of the process includes the first to fourth steps.

[0048] As the first step of the latter half of the process, as shown in Figure 9, the pump shaft 35 is assembled to the drive gear 32 by aligning the phase of the through hole 32a having a two-sided width provided on the inner diameter side of the drive gear 32 with the two-sided width formed at one end of the pump shaft 35.

[0049] 10, in the second step of the latter half, the gear shaft 3a is assembled to the pump shaft 35 by aligning the phase of the internal spline provided at the other end of the gear shaft 3a with the phase of the external spline provided at one end of the pump shaft 35. The gear shaft 3a is inserted with the spline phases aligned.

[0050] In the third step of the latter half of the process, as shown in FIG. 11, while rotating the gear shaft 3a, the phase of the internal spline provided at one end of the rotor shaft 2c is aligned with the phase of the external spline provided at the other end of the gear shaft 3a, and the gear shaft 3a is assembled to the rotor shaft 2c.

[0051] In the fourth step of the latter half of the process, as shown in Fig. 12, the gear shaft 3a is inserted until it abuts against the third bearing 23. When this fourth step is completed, the latter half of the process is completed.

[0052] As described above, according to the embodiment, the pump cover 34 is attached to the motor cover 13 from the inside of the case 4, which makes it possible to suppress oil leakage due to the oil pressure of the oil pump 7. Furthermore, the structure of the oil pump 7 makes it easy to assemble the in-wheel motor 1. [Explanation of symbols]

[0053] 1 In-wheel motor 2 motors 3 Reducer 4 cases 5 Hub bearings 6 axle hub 7. Oil pump 11 Motor case 12 Reducer case 13 Motor cover 21 First bearing 22 Second bearing 31 Pump Room 32 Drive gear 33 Driven gear 34 Pump cover 35 Pump shaft 40 Storage section 51 Resolver

Claims

1. a motor disposed inside the wheel; a reducer having an input shaft attached to a rotor shaft of the motor and transmitting power of the motor to the wheels; a case that accommodates the motor and the reducer; an oil pump disposed inside the case; Equipped with an in-wheel motor, the case including a motor case that houses the motor, a motor cover attached to the motor case, and a reducer case that is attached to the motor case on the opposite side to the motor cover and houses the reducer, The oil pump a pump chamber formed in the motor cover; a pump cover attached to the motor cover and closing the pump chamber; a pump shaft provided through the pump cover; a drive gear attached to the pump shaft and disposed within the pump chamber; a driven gear that meshes with the drive gear and is disposed inside the pump chamber, the pump shaft is attached to the input shaft of the reducer; The pump cover is fastened to the motor cover by bolts from the inside of the case, The pump cover is integrally formed with a positioning structure that determines the position of the pump shaft. An in-wheel motor characterized by:

2. The positioning structure has a boss portion through which the pump shaft is inserted, and supports the pump shaft via a bearing attached to an inner peripheral surface of the boss portion.

2. The in-wheel motor according to claim 1 .

3. the motor cover is formed in a cylindrical shape, protrudes toward the inside of the case in the axial direction, and has an accommodating portion that accommodates the pump cover, a bearing attached to the inside of the housing portion and rotatably supporting the rotor shaft; a resolver attached to the outside of the housing portion and configured to detect the rotation speed of the rotor shaft.

3. The in-wheel motor according to claim 1 or 2.

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