Drive unit

Abstract

To provide a drive unit capable of reducing oil churning loss while reducing vibration.SOLUTION: The drive unit includes: a motor placed in a motor housing; a gearbox connected to the motor via a rotation axis; and a gear case housing the gearbox. The gear case has a motor side end face, which is the end face on the motor housing side in the axial direction, and has multiple ribs connecting the motor side end face and the radial outer surface of the motor housing on the outside of the motor housing.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a drive device. [Background technology]

[0002] As a drive unit for electric vehicles, there is a drive unit that integrates a motor, an inverter, and a reducer to achieve compactness, lightness, and high output. In such a drive unit, the stator coil and bearings that make up the motor become hot during high-speed rotation, so they need to be cooled.

[0003] One known cooling method is an oil-cooled motor structure in which oil is poured over the motor coil to cool it. For example, the drive device in Patent Document 1 discloses a configuration in which, for the purpose of efficiently cooling the motor with oil, a catch tank is provided to collect the oil scooped up by the rotation of the rotor using ribs inside the motor housing, and the oil continues to circulate between the motor and the catch tank. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-205685 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the technology described in Patent Document 1, for example, in a low-temperature environment such as winter or in a cold region, when a vehicle is started in a state where the temperature has dropped and the oil viscosity is high, the oil needs to be heated because the high-viscosity oil accumulated in the lower part of the rotor increases the loss of agitation resistance. Also, when the reducer has three parallel shafts and a differential gear on the output shaft, the distance between the motor shaft and the output shaft increases and the gear case covering the differential gear is structured to protrude from the motor housing, which tends to increase the vibration of the gear case covering the differential gear, and this vibration needs to be suppressed. [Means for solving the problem]

[0006] A drive device comprising a motor housed in a motor housing, a reducer connected to the motor via a rotating shaft, and a gear case housing the reducer, wherein the gear case has a motor side end face which is the end face on the motor housing side in the axial direction, and has a plurality of ribs outside the motor housing connecting the motor side end face and the radial outer surface of the motor housing. Effect of the Invention

[0007] According to the present invention, it is possible to provide a drive device that realizes reduced oil churning loss and reduced vibration. [Brief description of the drawings]

[0008] [Figure 1] 1 is an overall view of a drive device according to an embodiment of the present invention; [Diagram 2] 2 is a cross-sectional view taken along line AA of FIG. 1 according to an embodiment of the present invention; [Diagram 3] 2 is a cross-sectional view of FIG. 1 according to an embodiment of the present invention; [Figure 4] 3 according to an embodiment of the present invention. [Diagram 5] 4 is a cross-sectional view taken along line D-D of FIG. 3 according to an embodiment of the present invention; [Figure 6] Enlarged view of area E in Figure 5

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The following description and drawings are examples for explaining the present invention, and appropriate omissions and simplifications have been made for clarity of explanation. The present invention can be implemented in various other forms. Unless otherwise specified, each component may be singular or plural.

[0010] In order to facilitate understanding of the invention, the position, size, shape, range, etc. of each component shown in the drawings may not represent the actual position, size, shape, range, etc. Therefore, the present invention is not necessarily limited to the position, size, shape, range, etc. disclosed in the drawings.

[0011] (One embodiment and overall configuration) (Fig. 1, Fig. 2) The drive unit 1 is used as a drive source for electrically powered vehicles such as electric cars and hybrid vehicles, and is mounted on the vehicle. The drive unit 1 has a motor 2, a reduction gear 3 having a gear 31 for reducing the rotational speed of the motor 2, and a drive shaft (not shown) for driving tires. The motor 2 is housed in a motor housing 20, and has a stator 4 and a rotor 5. The reduction gear 3 is housed in a gear case 30.

[0012] The motor housing 20 has a radial outer side surface 20a. The gear case 30 has a motor side end surface 30a which is an end surface on the motor housing 20 side in the axial direction. The gear case 30 also has a plurality of ribs 21 on the outside of the motor housing 20 which connect the motor side end surface 30a and the radial outer side surface 20a of the motor housing 20. The ribs 21 include a first rib 21a and a second rib 21b.

[0013] A space 6 is formed by the motor side end face 30a of the gear case 30, the radially outer side face 20a of the motor housing 20, the first rib 21a, and the second rib 21b. Although Fig. 1 shows the space 6 in an open state, a cover is provided to cover this opening.

[0014] The reduction gear 3 has, in a gear case 30, an input shaft 32a which is a rotating shaft connected to the motor shaft 50, an output shaft 32c which is a rotating shaft connected to the drive shaft, and a counter shaft 32b which is a rotating shaft provided between the input shaft 32a and the output shaft 32c. The output shaft 32c has a differential gear 33 which generates a rotation difference between the left and right drive shafts (not shown). The differential gear 33 is housed in the gear case 30 and connected to the reduction gear 3. The multiple ribs 21a, 21b are arranged on the motor 2 side when the differential gear 33 is used as a reference in the axial direction.

[0015] The input shaft 32a, the counter shaft 32b, and the output shaft 32c each include a gear 31. Each gear 31 is housed in a gear case 30. The inside of the gear case 30 is filled with oil for lubricating the gears 31. This oil also serves to cool the coil 40, which becomes hot when the motor 2 is in operation, thereby realizing an oil-cooling system for the motor 2.

[0016] (Fig. 3, Fig. 4) The motor housing 20 and the gear case 30 have, externally, a pipe 8 for circulating oil 7 that is supplied to the motor 2 and cools the motor 2. A pump 80 for sending the oil 7 and an oil cooler 81 for cooling the oil 7 are provided midway along the path of the pipe 8.

[0017] The space 6 (FIG. 1) functions as an oil tank for storing oil 7. The cover 22 covers an opening of the space 6 formed by the motor side end face 30a, the radially outer side face 20a, and the multiple ribs, thereby sealing the space 6. The space 6 is filled with the oil 7 that is supplied to the motor 2 to cool the motor 2.

[0018] The motor housing 20 has an oil supply hole 23 that penetrates a wall surface of the motor housing 20 and supplies oil 7 to the coil 40. The oil supply hole 23 connects the interior of the motor housing 20 to the space 6 as a flow path for the oil 7. In addition, the oil supply hole 23 is provided with a valve 24 that controls the connection and interruption of the flow of the oil 7 between the interior of the motor housing 20 and the space 6.

[0019] When cooling of the motor 2 is required, the pump 80 is started, and the oil 7 stored in the lower part of the gear case 30 is circulated through the piping 8, heat exchanged in the oil cooler 81, and then sent to the space 6. The oil 7 sent to the space 6 controls the valve 24 to open the oil supply hole 23, and is supplied into the motor housing 20, thereby cooling the coil 40 of the stator 4. In this way, the oil 7 circulates through the piping 8 to cool the motor 2 and the reducer 3.

[0020] When the vehicle is stopped, the drive unit 1 controls the valve 24 to close the oil supply hole 23 after turning off the power of the vehicle. Then, the pump 80 is operated for a predetermined time to send a predetermined amount of oil 7 accumulated in the gear case 30 to the space 6 via the pipe 8. Then, by stopping the pump 80 to stop the sending of the oil 7, the oil level of the oil 7 in the gear case 30 drops, while a predetermined amount of oil 7 is accumulated in the space 6. In this way, the vehicle starts from a state in which the oil level of the oil 7 in the gear case 30 is lowered, and therefore the agitation loss of the reduction gear 3 can be reduced.

[0021] When the drive unit 1 is driven, it vibrates due to electromagnetic excitation force generated in the gap between the rotor 5 and the stator 4, causing vibrations in each part of the drive unit 1. When the reducer 3 has three parallel shafts as shown in Fig. 2 and has a differential gear 33 on the output shaft 32c, the axial distance between the motor shaft 50 and the output shaft 32c becomes large, and the gear case 30 covering the differential gear 33 protrudes from the motor housing 20. Since the weight of the differential gear 33 is applied to the protruding gear case 30, the portion of the gear case 30 covering the differential gear 33 tends to vibrate in the vertical and horizontal directions.

[0022] In this way, the first rib 21a constituting the space 6, the second rib 21b connecting the motor side end face 30a of the gear case 30, and the cover 22 covering the opening increase the rigidity in the vertical and horizontal directions of the gear case 30 covering the differential device 33 (FIG. 2), and can reduce vibration. Even if the distance between the output shaft 32c and the motor shaft 50 increases, the motor side end face 30a of the gear case 30, the radial outer side face 20a of the motor housing 20, the first rib 21a, and the second rib 21b are adjusted accordingly to adjust the size of the space 6, thereby suppressing vibration of the drive unit 1.

[0023] (Fig. 5, Fig. 6) The first rib 21a is formed so as to be lower on the motor 2 side when viewed in radial cross section. Specifically, the space 6 is provided so as to decrease in height from the output shaft 32c toward the motor shaft 50, with an extension line connecting the output shaft 32c and the motor shaft 50 being set as the plane reference. This makes it easier for the oil 7 stored in the space 6 to accumulate on the motor 2 side, increasing the amount of oil 7 that comes into contact with the radial outer surface 20a of the motor housing 20.

[0024] As a result, even if it is difficult to sufficiently distribute the oil 7 to the parts that need cooling in a low-temperature environment such as winter or cold regions because the temperature of the oil 7 drops and the viscosity becomes high, the oil 7 in the space 6 is stored on the motor 2 side and the state of contact with the radially outer surface 20a is increased, so that the oil 7 can be warmed by the heat of the motor 2 and the viscosity can be reduced. Therefore, even when the vehicle is started in a low-temperature environment, the oil 7 can be easily distributed to the parts that need cooling, such as the coil 40 of the stator 4, and thus the agitation loss of the oil 7 in the reduction gear 3 when the vehicle is started can be reduced and the reliability of the motor 2 can be improved.

[0025] The material for forming the cover 22 is generally a metal material such as aluminum, but since there is a concern that the cover 22 will have a thin plate structure and will increase the radiated sound caused by vibration, the cover 22 may be formed of a resin material. In this way, the attenuation is greater than that of a metal material such as aluminum, and the radiated sound caused by the vibration of the cover 22 can be suppressed. In addition, since the resin material has higher insulation properties than a metal material, it is easier to heat the oil 7 stored in the space 6, so that even when the vehicle is parked for a short period of time in a low-temperature environment, the temperature of the oil 7 can be maintained at a low viscosity temperature, and an increase in the agitation loss of the oil 7 in the reduction gear 3 can be suppressed.

[0026] The motor housing 20, the motor side end surface 30a of the gear case 30, the first rib 21a, and the second rib 21b may be integrally formed. This increases the rigidity of the gear case 30 covering the differential device 33, and utilizes the weight of the oil 7 filled in the space 6 to suppress vertical and horizontal vibrations of the gear case 30 covering the differential device 33.

[0027] According to the embodiment of the present invention described above, the following advantageous effects are achieved.

[0028] (1) A drive device 1 including a motor 2 housed in a motor housing 20, a reducer 3 connected to the motor 2 via a rotating shaft, and a gear case 30 housing the reducer 3, the gear case 30 having a motor-side end face 30a that is an end face on the motor housing 20 side in the axial direction, and having a plurality of ribs 21 outside the motor housing 20 that connect the motor-side end face 30a to the radially outer side surface 20a of the motor housing 20. In this way, a drive device 1 can be provided that realizes reduced agitation loss of the oil 7 and reduced vibration.

[0029] (2) A cover 22 is provided to cover the opening of the space formed by the motor side end face 30a, the radially outer side face 20a, and the multiple ribs to seal the space 6, and the space 6 is filled with oil 7 that is supplied to the motor 2 to cool the motor 2. This can reduce the stirring loss of the reducer 3.

[0030] (3) The differential gear 33 is housed in the gear case 30 and is connected to the reduction gear 3, and the multiple ribs 21 are disposed on the motor 2 side when the differential gear 33 is used as a reference in the axial direction. In this way, the refrigerant oil 7 circulating through both the motor 2 and the reduction gear 3 can be stored in a space different from the motor 2 and the reduction gear 3.

[0031] (4) The multiple ribs 21 are formed so as to be lower on the motor 2 side when viewed in radial cross section. This makes it possible to lower the viscosity of the oil 7 and reduce the churning loss of the oil 7 in the reduction gear 3 when the vehicle starts.

[0032] (5) The material of the cover 22 is resin. This makes it easier for heat from the motor 2 to be transferred to the oil 7 stored in the space 6.

[0033] (6) The motor housing 20 and the gear case 30 are integrally formed. This makes it possible to increase the rigidity of the gear case 30 that covers the differential device 33.

[0034] The present invention is not limited to the above-described embodiment, and various modifications and other configurations can be combined without departing from the spirit of the present invention. Furthermore, the present invention is not limited to those having all of the configurations described in the above-described embodiment, and includes those in which some of the configurations are omitted. [Explanation of symbols]

[0035] 1 Drive unit 2 Motors 3 Reducer 4 Stator 5 Rotor 6 Space 7. Oil 8 Piping 20 Motor housing 20a Radial outer surface 21 Ribs 21a 1st Rib 21b 2nd Rib 22 Cover 23 Oil hole 24 Valve 30 Gear Case 30a Motor side end face 31 Gear 32a Input shaft 32b Counter Axis 32c output shaft 33 Differential device 40 Coil 50 Motor shaft 80 Pump 81 Oil cooler

Claims

1. A motor housed in a motor housing; A reducer connected to the motor via a rotating shaft; A drive device comprising: a gear case that houses the reducer, The gear case has a motor-side end face that is an end face on the motor housing side in the axial direction, and has a plurality of ribs on the outside of the motor housing that connect the motor-side end face and a radially outer surface of the motor housing. Drive unit.

2. 2. The drive device according to claim 1, a cover that covers an opening of a space defined by the motor side end surface, the radially outer side surface, and the plurality of ribs to seal the space; The space is filled with oil that is supplied to the motor to cool it. Drive unit.

3. 2. The drive device according to claim 1, a differential device housed in the gear case and connected to the reducer, The plurality of ribs are disposed on the motor side when the differential device is used as a reference in the axial direction. Drive unit.

4. 2. The drive device according to claim 1, The plurality of ribs are formed so that the motor side is lower when viewed in a radial cross section. Drive unit.

5. 3. The drive device according to claim 2, The cover is made of a resin. Drive unit.

6. 2. The drive device according to claim 1, The motor housing and the gear case are integrally formed. Drive unit.

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