In-wheel motor drive unit

Abstract

To provide an in-wheel motor drive device that is able to improve sealing performance.SOLUTION: An in-wheel motor drive device of the present invention includes: a motor case that houses a motor provided in a wheel of a drive wheel; a speed reducer case that houses a speed reducer configured to reduce a speed of rotation of the motor and output the rotation from an output shaft to the drive wheel; and a plurality of fastening bolts that fasten the motor case and the speed reducer case while a mating surface of the motor case and a mating surface of the speed reducer case are made to mate with each other. Among the plurality of fastening bolts, a pair of fastening bolts facing each other across a stator coil end portion of the motor in a radial direction orthogonal to an axial direction of the motor is disposed on the same straight line in the radial direction.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to an in-wheel motor drive device.

Background Art

[0002] Patent Document 1 discloses an in-wheel motor drive device that bolts together a motor case and a reduction gear case. In the in-wheel motor drive device disclosed in Patent Document 1, a first bolt is disposed inside the motor case and a second bolt is disposed along the outer circumference of the reduction gear case. Also, a sealing material is provided at the outer position of the first bolt and the inner position of the second bolt to ensure the sealing performance at the bolt fastening portion between the motor case and the reduction gear case.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the in-wheel motor drive device disclosed in Patent Document 1, since the bolt fastening interval around the coil end of the motor is large, it is difficult to suppress the deformation of the motor case and the reduction gear case when a force in the direction of separating the mating surfaces acts on each other. Therefore, there was room for improvement in ensuring the sealing performance between the mating surfaces against the deformation of the motor case and the reduction gear case.

[0005] The present invention has been made in view of the above problems, and an object thereof is to provide an in-wheel motor drive device capable of improving the sealing performance.

Means for Solving the Problems

[0006] In order to solve the above-mentioned problems and achieve the objective, the in-wheel motor drive device according to the present invention comprises a motor case housing a motor provided in the wheel of a drive wheel, a reduction gear case housing a reduction gear that reduces the rotation of the motor and outputs the reduced rotation from the output shaft to the drive wheel, and a plurality of fastening bolts that fasten the motor case and the reduction gear case together when the mating surfaces of the motor case and the mating surfaces of the reduction gear case are aligned, wherein of the plurality of fastening bolts, a pair of fastening bolts that face each other in the radial direction perpendicular to the axial direction of the motor, with the stator coil end portion of the motor in between, are arranged on the same straight line in the radial direction.

[0007] As a result, the in-wheel motor drive device according to the present invention can reduce the amount of deformation of the motor case and the reduction gear case, suppress the force acting in the direction that separates the mating surfaces, and improve the sealing performance between the mating surfaces.

[0008] Furthermore, in the above, a sealing material may be provided in the mating surface of the motor case and the mating surface of the reduction gear case, in a portion radially inward from the fastening bolt which is located radially inward from the stator coil end portion.

[0009] This improves sealing performance against external factors other than case deformation. [Effects of the Invention]

[0010] The in-wheel motor drive device according to the present invention has the effect of reducing the amount of deformation of the motor case and the reduction gear case, suppressing the force acting in the direction that separates the mating surfaces, and improving the sealing performance between the mating surfaces. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is an exploded perspective view showing the motor case, reduction gear case, and fastening bolts of an in-wheel motor drive system according to an embodiment. [Figure 2] Figure 2 shows the in-wheel motor drive unit as viewed from the opening side of the motor case. [Figure 3] Figure 3 is a cross-sectional view of the key part of the in-wheel motor near the fastening bolt, which is located radially inside the stator coil end. [Figure 4] Figure 4 is a cross-sectional view of the key part of the in-wheel motor near the fastening bolts, which are located radially outside the stator coil end portion. [Modes for carrying out the invention]

[0012] The following describes an embodiment of the in-wheel motor drive device according to the present invention. However, the present invention is not limited to this embodiment.

[0013] Figure 1 is an exploded perspective view showing the motor case 2, reduction gear case 3, and fastening bolt 4 of the in-wheel motor drive unit 1 according to an embodiment. Figure 2 is a view of the in-wheel motor drive unit 1 from the opening side of the motor case 2. Figure 3 is a cross-sectional view of the main part near fastening bolt 4A, which is located inside the stator coil end portion 7 in the radial direction of the in-wheel motor. Figure 4 is a cross-sectional view of the main part near fastening bolt 4B, which is located outside the stator coil end portion 7 in the radial direction of the in-wheel motor.

[0014] The in-wheel motor drive unit 1 according to this embodiment consists of a motor case 2 that houses the in-wheel motor and a reduction gear case 3 that houses the reduction gear. The in-wheel motor is an inner rotor type motor in which a rotor with a fixed rotating shaft is provided on the inner circumference side of the stator, and is installed inside the wheel of the drive wheel and is a drive source that outputs torque to the drive wheel. The reduction gear is configured to reduce the rotation of the in-wheel motor by multiple gears and output the torque from the output shaft to the drive wheel.

[0015] The motor case 2 and the reduction gear case 3 are fastened together by multiple fastening bolts 4 with the mating surface 21 provided on the motor case 2 and the mating surface 31 provided on the reduction gear case 3 aligned. The bolt shaft portion 41 of the fastening bolt 4 is inserted from the bolt hole 32 side, which is a through hole provided on the reduction gear case 3, toward the bolt hole 22, which is a bottomed hole provided on the motor case 2, and the bolt head 42 of the fastening bolt 4 is locked to the reduction gear case 3. For example, in Figure 3, with the bolt hole 22 of the motor case 2 and the bolt hole 32 of the reduction gear case 3 in communication, the bolt shaft portion 41 of the fastening bolt 4A is inserted from the bolt hole 32 side toward the bolt hole 22, and the bolt head 42 of the fastening bolt 4A is locked to the reduction gear case 3. Furthermore, in Figure 4, with the bolt hole 22 of the motor case 2 and the bolt hole 32 of the reduction gear case 3 in communication, the bolt shaft portion 41 of the fastening bolt 4B is inserted from the bolt hole 32 side toward the bolt hole 22, and the bolt head 42 of the fastening bolt 4A is locked to the reduction gear case 3.

[0016] As a result, the wall portion forming the bolt hole 22 of the motor case 2 functions as a partition wall separating the inside of the motor case 2 from the outside of the motor case 2, thereby suppressing oil leakage from the inside of the motor case 2 through the portion where the fastening bolt 4 is inserted.

[0017] In the in-wheel motor drive device 1 according to this embodiment, as shown in Figure 3, the bearing portion 23 of the motor case 2 and the bearing portion 33 of the reduction gear case 3 are in communication, forming a shaft hole portion 6 in which the rotating shaft of the in-wheel motor is positioned. In Figure 3, "AX" indicates the axis of the rotating shaft.

[0018] Furthermore, as shown in Figure 2, some of the fastening bolts 4, such as fastening bolts 4A, 4a, and 4c, are located inside the stator coil end portion 7 in the radial direction perpendicular to the axis AX of the in-wheel motor. Others of the fastening bolts 4, such as fastening bolts 4B, 4b, and 4d, are located outside the stator coil end portion 7 in the radial direction.

[0019] Among the plurality of fastening bolts 4, a pair of fastening bolts 4a and 4b that face each other with the stator coil end portion 7 sandwiched therebetween in the radial direction are arranged on the same straight line in the radial direction. The axial center O of the fastening bolt 4a 4a and the axial center O of the fastening bolt 4b 4b The center line L1 passing through them passes through the axial center O of the rotating shaft at the shaft hole portion 6 and extends in the normal direction with respect to the concentric circles with the axial center O. Among the plurality of fastening bolts 4, a pair of fastening bolts 4c and 4d that face each other with the stator coil end portion 7 sandwiched therebetween in the radial direction are arranged on the same straight line in the radial direction. The axial center O of the fastening bolt 4c 4c and the axial center O of the fastening bolt 4d 4d The center line L2 passing through them passes through the axial center O and extends in the normal direction with respect to the concentric circles with the axial center O.

[0020] Thus, in the in-wheel motor drive device 1 according to the embodiment, the bolt fastening distance (axial center distance) between the fastening bolt 4a and the fastening bolt 4b, and the bolt fastening distance (axial center distance) between the fastening bolt 4c and the fastening bolt 4d can be made the shortest. Therefore, when a load is input to the motor case 2 and the speed reducer case 3, the deformation amount of the motor case 2 and the speed reducer case 3 can be reduced, and the force in the direction of separating the mating surfaces 21 and 31 from each other can be suppressed, thereby improving the sealing performance. Furthermore, an increase in the size of the in-wheel motor drive device 1 can be suppressed.

[0021] Then, as shown in FIG. 3, on the mating surfaces 21 of the motor case 2 and 31 of the reduction gear case 3, a sealing material 5 is applied and provided on a portion inside the fastening bolt 4A in the radial direction, which is a direction orthogonal to the axis AX direction of the in-wheel motor. Thereby, it is possible to suppress the sealing material 5 from being peeled off and removed due to external factors, and it is possible to improve the sealing performance against external factors other than the deformation of the motor case 2 and the reduction gear case 3. The external factors referred to here include, for example, when the accumulated portion of the sealing material is exposed to the outside, the assembler touches the sealing material, or sand, water, etc. come into contact during vehicle running. Further, with the rotation of the rotating shaft of the in-wheel motor, oil leakage from inside the shaft hole portion 6 through the gap between the mating surfaces 21 and 31 can be effectively suppressed by the sealing material 5.

[0022] Note that the above-described configuration is merely an example of an embodiment of the present invention, and the present invention can be implemented in various modified and improved forms based on the knowledge of those skilled in the art without departing from the gist thereof.

Explanation of Reference Numerals

[0023] 1 In-wheel motor drive device 2 Motor case 3 Reduction gear case 4 Fastening bolt 5 Sealing material 6 Shaft hole portion 7 Stator coil end portion 21, 31 Mating surfaces 22 Bolt hole 23, 33 Bearing portions 32 Bolt hole 41 Bolt shaft portion 42 Bolt head

Claims

1. A motor case that houses the motor located inside the wheel of the drive wheel, A reduction gear case housing a reduction gear that reduces the rotation of the motor and outputs the reduced rotation to the drive wheel from the output shaft, With the mating surface of the motor case and the mating surface of the reduction gear case aligned, a plurality of fastening bolts fasten the motor case and the reduction gear case together, An in-wheel motor drive device equipped with, Of the plurality of fastening bolts, a pair of fastening bolts that face each other in the radial direction perpendicular to the axial direction of the motor, with the stator coil end portion of the motor in between, are arranged on the same straight line extending outward in the radial direction from the axial center of the output shaft. In-wheel motor drive system.

2. In the mating surface of the motor case and the mating surface of the reduction gear case, a sealing material is provided in the portion radially inward of the fastening bolt that is located radially inward of the stator coil end portion. The in-wheel motor drive device according to claim 1.

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