WO2020090662A1

WO2020090662A1 - In-wheel motor drive device

Info

Publication number: WO2020090662A1
Application number: PCT/JP2019/041925
Authority: WO
Inventors: 早織杉浦; 四郎田村
Original assignee: Ntn株式会社
Priority date: 2018-11-01
Filing date: 2019-10-25
Publication date: 2020-05-07
Also published as: JP2020069973A; JP7149163B2

Abstract

In a casing (10) housing a motor unit of an in-wheel motor drive device, a bearing fitting (63) where a roller bearing (28) is fitted is provided in a position between a first space (S10) on the rotor (23) side and a second space (S20) on the opposite side, the first space (S10) and the second space (S20) being arranged separated from each other in the axial direction. The bearing fitting has a protruding part (63p) which protrudes towards the first space beyond the position (L1) of the end face of the roller bearing arranged facing the first space, and which receives lubricant supplied to the roller bearing. An exhaust path (48) for discharging the lubricant received in the protruding part to the second space (S20) is formed in the bearing fitting.

Description

In-wheel motor drive

The present invention relates to an in-wheel motor drive device, and more particularly to an in-wheel motor drive device provided with a lubricating oil supply mechanism for supplying lubricating oil to a motor section.

The in-wheel motor drive is located inside the wheel of the vehicle, so the size of the space where the in-wheel motor drive can be installed is limited. Therefore, the in-wheel drive device is generally provided with a speed reduction unit that reduces the rotation of the motor unit and transmits the rotation to the wheel hub bearing unit in order to obtain high torque without increasing the size of the motor unit.

Since the motor section rotates at a high speed, as shown in, for example, Japanese Unexamined Patent Application Publication No. 2008-44439 (Patent Document 1), the in-wheel motor drive device cools the heat generating elements of the motor section and lubricates the bearings. A lubricating oil supply mechanism (oil pump, oil flow path, etc.) for supplying lubricating oil to the motor section is provided.

In Patent Document 1, a large amount of oil is required to cool the stator of the motor unit, but when a large amount of oil is applied to the bearing that supports the motor shaft, rotation loss occurs. A technique has been proposed in which the flow path is devised to adjust the amount of oil supplied to the support bearing.

JP, 2008-44439, A

Patent Document 1 proposes a technique for reducing the rotation loss due to the lubricating oil being applied to the support bearing of the motor shaft as described above, but when a large amount of lubricating oil is applied to the rotor that rotates at high speed together with the motor shaft. Since it causes the rotation resistance of the rotor, it is preferable to have a structure in which lubricating oil is not applied to the rotor too much.

In particular, in the case of the structure in which the support bearing overlaps with the axial position of the rotor as in Patent Document 1, the gap between the bearing fitting portion provided in the casing and the rotor support portion becomes narrow, so that the lubricating oil can cause this gap. When passing, it becomes the rotational resistance of the rotor that rotates at high speed.

The present invention has been made to solve the above problems, and an object thereof is to provide an in-wheel motor drive device that can reduce the rotational resistance of the rotor of the motor section.

An in-wheel motor drive according to an aspect of the present invention is an in-wheel motor drive arranged in a wheel of a wheel, the rotor, a motor rotating shaft that rotates integrally with a rotor, and an axial end portion of the motor rotating shaft. A motor part including a rolling bearing that rotatably supports the motor, a casing that houses the motor part, a first space on the rotor side that is provided in the casing and is axially separated from each other, and a second space on the opposite side. And a bearing fitting portion which is positioned between the space and the rolling bearing. The bearing fitting portion has a protruding portion that protrudes toward the first space beyond the position of the end surface of the rolling bearing arranged so as to face the first space and receives the lubricating oil supplied to the rolling bearing. The bearing fitting portion is formed with a discharge passage for discharging the lubricating oil received by the protrusion to the second space.

Preferably, the bearing fitting portion is provided with a supply passage for supplying lubricating oil from above to the rolling bearing, and the discharge passage is arranged below the axis of the motor rotating shaft.

It is desirable that the bottom surface of the discharge path be inclined so that the second space side is lower than the first space side.

The rotor includes a rotor core and a rotor support portion that supports the rotor core. Preferably, at least a part of the rolling bearing overlaps the axial position of the rotor.

The first space is included in the motor chamber in which the rotor and the central portion of the motor rotation shaft are arranged, and the second space is included in the sensor chamber in which the rotation sensor that detects the rotation of the motor rotation shaft is arranged.

The in-wheel motor drive device further includes a partition wall portion arranged between the bearing fitting portion and the sensor chamber. In this case, it is preferable that the discharge passage includes a groove formed on the inner peripheral surface of the bearing fitting portion and a discharge hole that axially penetrates the partition wall portion.

At the tip of the protruding part, a return part arranged so as to intersect the groove may be provided.

The rotation sensor is preferably fixed to the end surface of the partition wall by a substantially C-shaped fixing member arranged so that the notch is located at the discharge hole.

∙ A communication hole that connects the motor chamber and the sensor chamber is provided at a position below the discharge path. In this case, it is desirable that the motor chamber be provided with a barrier portion that prevents the lubricating oil returned from the sensor chamber to the motor chamber through the communication hole from scattering to the rotor.

Also, it is desirable that the signal line of the rotation sensor be fixed to the barrier.

According to the present invention, since the amount of lubricating oil flowing to the rotor side is reduced, it is possible to reduce the rotational resistance of the rotor of the motor section.

FIG. 3 is a vertical cross-sectional view showing the in-wheel motor drive device according to the embodiment of the present invention cut along a predetermined plane and developed. It is a transverse cross-sectional view which shows typically the internal structure of the deceleration part of the in-wheel motor drive device which concerns on embodiment of this invention. FIG. 3 is an external view of the in-wheel motor drive device according to the embodiment of the present invention as viewed from the inside in the vehicle width direction. FIG. 4 is a sectional view of the in-wheel motor drive device taken along line IV-IV in FIG. 3. It is a longitudinal cross-sectional view which shows typically the internal structure of the motor casing in embodiment of this invention. It is a figure which shows typically the bearing lubrication structure in embodiment of this invention, and is a fragmentary sectional view which expanded and showed VI part of FIG. FIG. 3 is a perspective view of the rear cover alone as seen from the inside in the embodiment of the present invention. In the embodiment of the present invention, it is a perspective view of the state in which the rolling bearing is attached to the rear cover as seen from the inside. FIG. 3 is a plan view of the rear cover unit as seen from the outside in the embodiment of the present invention. FIG. 3 is a plan view of a state in which a resolver is attached to a rear cover as seen from the outside, according to the embodiment of the present invention. FIG. 9 is a partial cross-sectional view schematically showing a bearing lubrication structure in a modified example of the embodiment of the present invention. It is a longitudinal cross-sectional view which shows typically the internal structure of the motor casing in the comparative example of this invention. It is a figure which shows typically the bearing lubrication structure in the comparative example of this invention, and is a fragmentary sectional view which expanded and showed the XIII part of FIG.

Embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts will be denoted by the same reference characters and description thereof will not be repeated.

<Basic configuration example of in-wheel drive device>
First, a basic configuration example of an in-wheel motor drive device 1 according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a vertical cross-sectional view showing an in-wheel motor drive device 1 according to an embodiment of the present invention cut along a predetermined plane and developed. FIG. 2 is a transverse cross-sectional view showing the internal structure of the speed reducer 31 of the in-wheel motor drive device 1, schematically showing a state viewed from the vehicle width direction outer side. The predetermined plane shown in FIG. 1 is a developed plane in which the plane including the axis M and the axis N shown in FIG. 2 and the plane including the axis N and the axis O are connected in this order. In FIG. 1, the left side of the drawing represents the vehicle width direction outside (outboard side), and the right side of the drawing represents the vehicle width direction inside (inboard side).

The in-wheel motor drive device 1 is a vehicle motor drive device that drives the wheels of an electric vehicle. The in-wheel motor drive device 1 is arranged in a wheel W of a wheel and is connected to a vehicle body (not shown). The in-wheel motor drive device 1 can drive an electric vehicle at a speed of 0 to 180 km / h.

The in-wheel motor drive device 1 includes a wheel hub bearing portion 11 provided at the center of the wheel W, a motor portion 21 that drives a wheel, and a speed reducing portion that reduces the rotation of the motor portion 21 and transmits the rotation to the wheel hub bearing portion 11. And 31. The in-wheel motor drive device 1 includes a casing 10 that forms an outer shell of the in-wheel motor drive device 1. The casing 10 includes a motor casing 29 and a reduction gear casing 39, which will be described later.

The motor unit 21 and the reduction unit 31 are arranged offset from the axis O of the wheel hub bearing unit 11. The axis O extends in the vehicle width direction and coincides with the axle. In the present embodiment, one side in the axis O direction is the outer side in the vehicle width direction, and the other side in the axis O direction is the inner side in the vehicle width direction.

Regarding the position in the direction of the axis O, the wheel hub bearing portion 11 is arranged on one side in the axial direction of the in-wheel motor drive device 1, the motor portion 21 is arranged on the other side in the axial direction of the in-wheel motor drive device 1, and the speed reduction portion 31 is the motor portion. It is arranged on the one side in the axial direction with respect to 21, and the axial direction position of the reduction gear portion 31 overlaps with the axial direction position of the wheel hub bearing portion 11.

The wheel hub bearing portion 11 is, for example, a rotating inner ring / fixed outer ring, and serves as an inner ring 12 as a rotating ring (hub ring) coupled to the wheel W, and a fixed ring coaxially arranged on the outer diameter side of the inner ring 12. It has an outer ring 13 and a plurality of rolling elements 14 arranged in an annular space between the inner ring 12 and the outer ring 13. The rotation center of the inner ring 12 coincides with the axis O passing through the center of the wheel hub bearing 11.

The outer ring 13 penetrates the front portion 39f of the reduction gear casing 39 and is connected and fixed to the front portion 39f. The front portion 39f is a casing wall portion that covers one end of the reduction gear casing 31 in the axis O direction of the reduction gear casing 39.

The inner ring 12 is a tubular body that is longer than the outer ring 13, and is passed through the center hole of the outer ring 13. A coupling portion 12f is formed at one end of the inner ring 12 projecting from the outer ring 13 to the outside (outer side in the vehicle width direction) in the axis O direction. The coupling portion 12f is a flange and constitutes a coupling portion for coaxially coupling with the brake disc and the wheel. The inner ring 12 is coupled to the wheel W at the coupling portion 12f and rotates integrally with the wheel.

The outer peripheral surface of the inner ring 12 at the central portion in the direction of the axis O constitutes the inner raceway surface of the rolling element 14. The rolling elements 14 may be arranged in a plurality of rows. The output shaft 38 of the speed reducer 31 is inserted into the center hole at the other end of the inner ring 12 in the direction of the axis O for spline fitting or serration fitting.

The motor unit 21 has a motor rotating shaft 22, a rotor 23, and a stator 24, and they are sequentially arranged in this order from the axis M of the motor unit 21 toward the outer diameter side. The motor unit 21 is housed in the motor casing 29. The axis M, which is the center of rotation of the motor rotation shaft 22 and the rotor 23, is arranged in front of the vehicle with respect to the center axis of the wheel, that is, the axis O of the wheel hub bearing 11.

The rotor 23 is arranged on the inner diameter side of the stator 24 and is fixed to the motor rotating shaft 22. The rotor 23 includes a rotor core 23a composed of a permanent magnet or a magnetic body, and a rotor support portion 23b that supports the rotor core 23a. The rotor support portion 23b is integrally provided in the axial center portion of the motor rotation shaft 22. The rotor support portion 23b includes a pair of flange portions that cover both axial end surfaces of the rotor core 23a. At least one of the pair of flange portions may be configured by an end member that is separate from the motor rotating shaft 22.

The cylindrical portion of the motor casing 29 surrounds the outer circumference of the stator 24. One end of the cylindrical portion of the motor casing 29 in the direction of the axis M is connected to the back surface portion 39b of the reduction gear casing 39. The back surface portion 39b is a wall portion that covers the other end of the reduction gear casing 31 in the axis M direction (axis O direction) of the reduction gear casing 39. The other end of the cylindrical portion of the motor casing 29 in the axis M direction is sealed by a plate-shaped rear cover 29v. The rear cover 29v is a wall portion that forms an inner end surface of the motor casing 29 in the vehicle width direction. In this way, the motor chamber S1 is formed between the rear surface portion 39b of the reduction gear casing 39 and the rear cover 29v.

Both ends of the motor rotation shaft 22 are rotatably supported by the rear portion 39b of the reduction gear casing 39 and the rear cover 29v via rolling

bearings

27 and 28. The rolling bearing 27 is fitted in a bearing fitting portion 61 provided on the back surface portion 39 b of the reduction gear casing 39. The rolling bearing 28 is fitted in a bearing fitting portion 63 provided on the flat wall portion 91 of the rear cover 29v. It should be noted that in the motor chamber S1, all of the rotor 23 and the stator 24 and the central portion in the axial direction of the motor rotating shaft 22 (the portion located between the pair of rolling bearings 27 and 28) are arranged.

A resolver 80 is provided at the other end of the motor rotation shaft 22 in the direction of the axis M. The resolver 80 is a rotation sensor for detecting the rotation of the motor rotation shaft 22. The resolver 80 is housed in the sensor chamber S2 provided in the rear cover 29v. The sensor chamber S2 is a space defined by a tubular wall 92 that projects inward in the vehicle width direction from a flat wall portion 91 of the rear cover 29v, and a lid portion 93 that covers the opening of the tubular wall 92. The lid 93 is bolted to the end surface of the tubular wall 92.

The resolver 80 is fitted in a tubular portion 62 provided on the wall portion 91 of the rear cover 29v so as to be adjacent to the rolling bearing 28. That is, the tubular portion 62 includes the bearing fitting portion 63 into which the rolling bearing 28 is fitted and the sensor fitting portion 65 into which the resolver 80 is fitted (see FIG. 6).

The reduction unit 31 includes, for example, a three-axis parallel shaft gear reducer having axes O, N, and M extending parallel to each other as a reduction mechanism that reduces the rotation of the motor rotation shaft 22. Specifically, the reduction unit 31 includes an input shaft 32 that is coaxially coupled to the motor rotation shaft 22, an input gear 33 that is coaxially provided on the outer peripheral surface of the input shaft 32, and a plurality of

intermediate gears

34 and 36. An intermediate shaft 35 that is coupled to the centers of the

intermediate gears

34 and 36, an output shaft 38 that is coaxially coupled to the inner ring 12 of the wheel hub bearing portion 11, and an output gear 37 that is coaxially provided on the outer peripheral surface of the output shaft 38. .. The reduction gear unit 31 is housed in the reduction gear casing 39.

The input shaft 32 is rotatably supported by the front portion 39f and the rear portion 39b of the reduction gear casing 39 on both ends of the input gear 33 via rolling

bearings

32a and 32b. The axis N, which is the center of rotation of the intermediate shaft 35, extends parallel to the axis O. Both ends of the intermediate shaft 35 are rotatably supported by the front surface portion 39f and the rear surface portion 39b of the speed reducer casing 39 via

bearings

35a and 35b. At the center of the intermediate shaft 35, a first intermediate gear 34 and a second intermediate gear 36 are provided coaxially with the axis N of the intermediate shaft 35. The diameter of the first intermediate gear 34 is larger than the diameter of the second intermediate gear 36. The large-diameter first intermediate gear 34 is arranged on the other side of the second intermediate gear 36 in the axis line N direction and meshes with the small-diameter input gear 33. The small-diameter second intermediate gear 36 is arranged on one side of the first intermediate gear 34 in the axis N direction and meshes with the large-diameter output gear 37.

The axis N of the intermediate shaft 35 is arranged above the axis O and the axis M, as shown in FIG. The axis N of the intermediate shaft 35 is arranged in front of the axis O in the vehicle and rear of the axis M in the vehicle.

The output gear 37 is provided coaxially at the center of the output shaft 38. The output shaft 38 extends along the axis O. One end of the output shaft 38 in the direction of the axis O is inserted into the center hole of the inner ring 12 and fitted so as not to rotate relative to each other. Such fitting is spline fitting or serration fitting. A central portion (one end side) of the output shaft 38 in the direction of the axis O is rotatably supported by the front portion 39f of the speed reducer casing 39 via a rolling bearing 38a. The other end (the other end) of the output shaft 38 in the direction of the axis O is rotatably supported by the back surface portion 39b of the speed reducer casing 39 via a rolling bearing 38b.

The reduction gear unit 31 engages with the small-diameter drive gear and the large-diameter driven gear, that is, with the engagement of the input gear 33 and the first intermediate gear 34, and with the engagement of the second intermediate gear 36 and the output gear 37. The rotation is decelerated and transmitted to the output shaft 38. The rotating element from the input shaft 32 to the output shaft 38 of the speed reduction unit 31 constitutes a drive transmission path that transmits the rotation of the motor unit 21 to the inner ring 12. The input shaft 32, the intermediate shaft 35, and the output shaft 38 are supported on both sides by the above-mentioned rolling bearing. These rolling

bearings

32a, 35a, 38a, 32b, 35b, 38b are radial bearings.

The reducer casing 39 includes a tubular portion, and a plate-shaped front portion 39f and a back portion 39b that cover both ends of the tubular portion. The tubular portion covers the internal components of the speed reducing portion 31 so as to surround the axes O, N, M extending in parallel with each other. The plate-shaped front portion 39f covers the internal components of the reduction gear unit 31 from one side in the axial direction. The plate-shaped rear surface portion 39b covers the internal components of the speed reducing portion 31 from the other side in the axial direction.

The back surface portion 39b of the reduction gear casing 39 is also a partition wall that is coupled to the motor casing 29 and partitions the internal space of the reduction gear portion 31 and the internal space of the motor portion 21. The motor casing 29 is supported by the reduction gear casing 39 and projects from the reduction gear casing 39 to the other side in the axial direction.

When electric power is supplied to the stator 24 of the motor unit 21 from the outside of the in-wheel motor drive device 1, the rotor 23 of the motor unit 21 rotates, and the rotation is output from the motor rotation shaft 22 to the reduction unit 31. The deceleration unit 31 decelerates the rotation input from the motor unit 21 to the input shaft 32 and outputs it from the output shaft 38 to the wheel hub bearing unit 11. The inner ring 12 of the wheel hub bearing portion 11 rotates at the same number of revolutions as the output shaft 38, and drives the wheel mounted and fixed to the inner ring 12.

In the present embodiment, the reduction unit 31 of the in-wheel motor drive device 1 is shown as an example of a three-axis parallel shaft gear reducer, but the reduction unit is, for example, a four-axis parallel shaft gear reducer. For example, it may be a gear reducer of another type or a gear reducer having no gear.

<About the lubricating oil supply mechanism>
The in-wheel motor drive device 1 supplies the lubricating oil for cooling the heat generating elements (such as the stator 24) of the motor section 21 and for lubricating the rotating elements (rolling bearings, gears, etc.) of the motor section 21 and the reduction section 31. It has a mechanism.

The lubricating oil supply mechanism in the present embodiment will be described with reference to FIGS. 3 to 5. FIG. 3 is an external view of the in-wheel motor drive device 1 viewed from the inside in the vehicle width direction. FIG. 4 is a sectional view of the in-wheel motor drive device 1 taken along the line IV-IV in FIG. FIG. 5 is a vertical cross-sectional view schematically showing the internal structure of the motor casing 29.

The in-wheel motor drive device 1 mainly serves as a lubricating oil supply mechanism in an upper position than the oil tank 40 provided in the lower portion of the casing 10, the oil pump 43 pumping the lubricating oil from the oil tank 40, and the stator 24. And an oil passage 45 arranged along the axis M direction. In the following description, the direction along the axis M direction of the motor unit 21 is simply referred to as the axial direction.

The oil pump 43 sucks lubricating oil from the oil tank 40 via the suction oil passage 41, and discharges the sucked lubricating oil to the discharge oil passage 44. The oil pump 43 is driven in association with the rotation of the motor rotary shaft 22. The oil pump 43 is, for example, coaxially coupled to the output shaft 38 and driven by the output shaft 38. In this case, the oil pump 43 is driven at the same rotation speed as the wheels. The oil pump 43 is, for example, a trochoid pump having an outer rotor and an inner rotor.

In the present embodiment, the oil tank 40 is provided below the speed reducer casing 39. The oil pump 43 is housed in, for example, a pump chamber 42 that is integrally provided in the back surface portion 39b of the speed reducer casing 39. The pump chamber 42 is arranged on the vehicle rear side with respect to the position of the outer peripheral surface of the motor portion 21 (stator 24). The other end 38f of the output shaft 38 in the O-axis direction extends to the pump chamber 42, and the oil pump 43 is connected to the other end 38f of the output shaft 38 in the O-axis direction.

The discharge oil passage 44 includes an ascending oil passage 44a formed within the wall thickness of the rear cover 29v. The ascending oil passage 44a extends vertically in the flat wall portion 91 and is connected to one end of the oil passage 45 at the upper end. Since the oil passage 45 is disposed above the stator 24, as shown in FIG. 3, the rising oil passage 44a extends obliquely so that the upper end is located on the vehicle front side with respect to the lower end.

The oil passage 45 is composed of a cylindrical portion 45a provided at the upper end of the rear cover 29v and a tubular member (hereinafter referred to as "oil pipe") 45b having one end fitted in the cylindrical portion 45a. The cylindrical portion 45a intersects (perpends to) the upper end of the rising oil passage 44a and extends in the axial direction. The oil pipe 45b is attached and fixed to the upper portion of the motor casing 29, and penetrates the back surface portion 39b of the reduction gear casing 39 to extend in the axial direction. That is, the oil pipe 45b is arranged across the motor chamber S1 and the deceleration chamber S3. The other end of the oil pipe 45b is typically closed.

A plurality of holes (hereinafter referred to as "oil holes") 46 are provided in the oil passage 45 at intervals along the axial direction. As a result, the lubricating oil flowing through the oil passage 45 is discharged radially from the oil hole 46. The positions of the oil holes 46 in the radial direction may be different from each other. In the motor chamber S1, at least one of the plurality of oil holes 46 is located within the axial width of the stator 24, and the other at least one is located outside the axial width of the stator 24. The latter oil hole 46 may be provided in the cylindrical portion 45a.

In the motor chamber S1, the lubricating oil discharged from the oil hole 46 is supplied to the stator 24 and the rolling

bearings

27 and 28 of the motor unit 21. The lubricating oil used for cooling the stator 24 and lubricating the rolling

bearings

27, 28 returns to the oil tank 40 provided in the lower portion of the casing 10.

Here, as shown in FIG. 5, in order to reduce the axial dimension of the in-wheel motor drive device 1, the rolling bearing 28 supporting the other axial end of the motor rotation shaft 22 is formed in the axial direction of the rotor 23. It overlaps with the position. That is, the rolling bearing 28 is wholly or partially arranged within the axial width D of the rotor 23. In addition, in the present embodiment, the rolling bearing 27 that supports one end portion of the motor rotation shaft 22 in the axial direction is also arranged in whole or in part within the axial width D of the rotor 23.

Since the in-wheel motor drive device 1 is required to be downsized not only in the axial direction but also in the radial direction, it is provided between the rotor fitting portion 63 and the bearing fitting portion 63 (cylindrical portion 62) into which the rolling bearing 28 is fitted. The radial distance of the gap S13 is very small. In the present embodiment, the outer diameter dimension of the portion of the bearing fitting portion 63 located on the inner diameter side of the rotor support portion 23b is smaller than the other portions. The outer peripheral surface of the tubular portion 62 has a tapered surface 62a that is tapered so as to taper toward the tip side (one side in the axial direction).

The lubrication structure of the rolling bearing 28 in the in-wheel motor drive device 1 adopting such a structure will be described in detail below.

<Lubrication structure of the rolling bearing 28>
The lubricating structure of rolling bearing 28 in the present embodiment will be described with further reference to FIG. FIG. 6 is a partial cross-sectional view showing an enlarged main part (VI part) of FIG.

The tubular portion 62 having the bearing fitting portion 63 is provided at the boundary between the motor chamber S1 and the sensor chamber S2, and the bearing fitting portion 63 includes the first space S10 and the sensor chamber included in the motor chamber S1. It is located between the second space S20 included in S2. In the present embodiment, the first space S10 is the outer peripheral surface of the central shaft portion 22a that extends straight from one end to the other end of the motor rotation shaft 22 in the axial direction, and the end surface of the connecting portion 22b between the central shaft portion 22a and the rotor 23. An annular space surrounded by the inner peripheral surface of the rotor support portion 23b.

The tubular portion includes a partition wall portion 64 arranged between the bearing fitting portion 63 and the sensor chamber S2. The rolling bearing 28 housed in the bearing fitting portion 63 is arranged so as to face the end surface of the partition wall portion 64. The sensor fitting portion 65 into which the resolver 80 is fitted is included in the partition wall portion 64. In the present embodiment, the sensor fitting portion 65 is formed in a C shape so that the inner peripheral surface 65a thereof is an arc surface. The inner peripheral surface 65a of the sensor fitting portion 65 has a smaller diameter than the inner peripheral surface 63a of the bearing fitting portion 63.

A supply passage 47 for supplying lubricating oil to the rolling bearing 28 is formed on the upper portion of the bearing fitting portion 63. The supply passage 47 is a through hole that penetrates the bearing fitting portion 63 (cylindrical portion 62) in the radial direction. As shown in FIG. 5, the lubricating oil discharged from the oil hole 46 of the oil passage 45 passes through the supply passage 47 and is supplied to the rolling bearing 28. The lubricating oil that lubricates the rolling bearing 28 flows back to the oil tank 40 provided in the lower portion of the casing 10. Note that, in FIG. 12, the position of the oil surface of the lubricating oil stored in the oil tank 40 is shown by a two-dot chain line.

Here, as shown in the comparative example (in-wheel motor drive device 100) of FIGS. 12 and 13, only the supply passage 47 is formed in the bearing fitting portion 163 of the tubular portion 162, and the bearing fitting portion 163 is formed. When the position (L10) of the end surface of 163 and the position (L10) of the end surface of the rolling bearing 28 match, the lubricating oil that lubricates the rolling bearing 28 normally flows down the motor chamber S1 from the first space S10 side. Then return to the oil tank 40.

In this case, the lubricating oil discharged into the first space S10 flows down through the narrow gap S13 between the rotor support portion 23b and the bearing fitting portion 163. While the vehicle is traveling, the rotor 23 rotates at a high speed, and the lubricating oil passes through this gap, which causes rotation resistance of the rotor 23.

On the other hand, in the present embodiment, as shown in FIG. 6, the position L2 of the end surface of the bearing fitting portion 63 facing the first space S10 is greater than the position L1 of the end surface of the rolling bearing 28 in the first space. It is located on the S10 side. That is, the bearing fitting portion 63 has the annular protruding portion 63p protruding toward the first space S10 side from the position L1 of the end surface of the rolling bearing 28. As a result, the protruding portion 63p can receive (at least a part of) the lubricating oil that lubricates the rolling bearing 28.

Further, in the bearing fitting portion 63, a discharge passage 48 for discharging the lubricating oil received by the protruding portion 63p to the sensor chamber S2 (second space S20) is formed along the axial direction. As a result, the lubricating oil used to lubricate the rolling bearing 28 can be diverted to the sensor chamber S2 via the discharge passage 48, and thus the narrow gap S13 between the rotor support portion 23b and the bearing fitting portion 63. The amount of lubricating oil passing through can be reduced. Therefore, according to the present embodiment, the rotation resistance of the rotor 23 can be reduced.

A specific configuration example of the discharge path 48 will be described with further reference to FIGS. 7 to 9. FIG. 7 is a perspective view of the rear cover 29v alone as seen from the inside (from the outside in the vehicle width direction). FIG. 8 is a perspective view of the state in which the rolling bearing 28 is attached to the rear cover 29v as viewed from the inside. FIG. 9 is a plan view of the rear cover 29v alone viewed from the outside (from the inside in the vehicle width direction).

The discharge passage 48 is arranged below the axis M of the motor rotating shaft 22. The discharge passage 48 includes a groove 63b provided on the inner peripheral surface 63a of the bearing fitting portion 63, and a discharge hole 64b extending continuously from the groove 63b and penetrating the partition wall portion 64 in the axial direction. The discharge hole 64b is provided in a portion (hereinafter, referred to as a "flat portion") 64f of the partition wall portion 64 that does not have the C-shaped sensor fitting portion 65.

It is desirable that the groove 63b is also provided on the protruding portion 63p. This makes it easier to collect the lubricating oil received at the protruding portion 63p. In the present embodiment, the groove 63b extends from one end of the bearing fitting portion 63 in the axial direction to the other end thereof.

Moreover, it is desirable that the bottom surface of the discharge path 48 is inclined so that the second space S20 side is lower than the first space S10 side. Thereby, most of the lubricating oil received at the protruding portion 63p can be discharged to the second space S20. The slope may be provided only in the groove 63b of the discharge path 48.

When the discharge passage 48 is provided so as to penetrate the partition wall portion 64 facing the sensor chamber S2 as in the present embodiment, the resolver 80 is attached at a position where it does not interfere with the discharge passage 48 (that is, the discharge hole 64b). Be done. The fixing structure of the resolver 80 will be described with further reference to FIG. FIG. 10 is a plan view of the state in which the resolver 80 is attached to the rear cover 29v as seen from the outside (from the inside in the vehicle width direction).

The resolver 80 has a cylindrical main body portion 80a and a rectangular parallelepiped connection portion 80b arranged so as to contact the outer peripheral surface of the main body portion 80a in a plan view. The body portion 80a and the connection portion 80b are integrally formed. The main body portion 80a is fitted into the inner peripheral surface 65a of the sensor fitting portion 65. The connection portion 80b is provided so as to contact the flat portion 64f of the partition wall portion 64. As shown in FIG. 10, the wire connection portion 80b is arranged at a position where it does not overlap the discharge path 48 (discharge hole 64b).

The resolver 80 is fixed to the end surface of the sensor fitting portion 65 by a fixing member 82 formed of a thin plate. The fixing member 82 is formed in a substantially C shape, not in an annular shape. That is, the fixing member 82 has the cutout portion 82b in a part in the circumferential direction.

The fixing member 82 is arranged so as to come into contact with the arc-shaped edge of the main body 80a of the resolver 80, and is fixed to the end surface of the tubular portion 62 (sensor fitting portion 65) by a plurality of bolts 83. Specifically, the fixing member 82 has a plurality of through holes provided at intervals in the circumferential direction, and the end face of the sensor fitting portion 65 has a plurality of through holes at positions corresponding to the through holes. A female screw hole 65b is provided. The resolver 80 is fixed to the sensor fitting portion 65 by inserting the shaft portion of the bolt 83 into the through hole of the fixing member 82 and screwing it into the female screw hole 65 b of the sensor fitting portion 65.

As described above, since the discharge hole 64b of the discharge path 48 is provided in the flat portion 64f of the partition wall portion 64, it is exposed without being covered by the fixing member 82. That is, the resolver 80 is fixed to the end surface of the partition wall portion 64 by the fixing member 82 arranged such that the cutout portion 82b is located in the discharge hole 64b.

In this way, the outlet of the discharge path 48 is arranged so as not to overlap both the connection portion 80b of the resolver 80 and the fixing member 82. As a result, the resolver 80 and the fixing member 82 do not hinder the discharge of the lubricating oil that has passed through the discharge passage 48, so that the lubricating oil can be appropriately discharged to the sensor chamber S2. The shapes of the resolver 80 and the fixing member 82 are not limited to the above examples as long as the resolver 80 and the fixing member 82 can be arranged so as not to interfere with the outlet of the discharge path 48.

Here, the signal line 81 extending from the connection portion 80b is once drawn into the motor chamber S1 through the communication hole 71 that connects the motor chamber S1 and the sensor chamber S2, and then the signal line outlet provided in the rear cover 29v. Drawn from 72. The communication hole 71 is provided at a position below the discharge path 48. Therefore, as shown in FIGS. 5 and 6, the lubricating oil discharged from the discharge passage 48 into the sensor chamber S2 is returned to the motor chamber S1 through the communication hole 71.

It is desirable that the motor chamber S1 be provided with a barrier portion 66 for preventing the lubricating oil returned from the sensor chamber S2 through the communication hole 71 from splashing on the end surface of the rotor 23. The barrier portion 66 is arranged below the bearing fitting portion 63 so that at least a part thereof faces the end surface of the rotor 23. Further, when viewed in the axial direction, at least a part of the barrier portion 66 overlaps a part of the communication hole 71 (for example, a part on the lower side). As a result, it is possible to more sufficiently reduce the possibility that the lubricating oil used to lubricate the rolling bearing 28 will become the rotational resistance of the rotor 23.

In the present embodiment, the barrier 66 is composed of the wiring fixing member 73 shown in FIG. The wire fixing member 73 is formed, for example, by bending a plate-shaped member into a substantially L shape, and includes a vertical plate portion 73a extending in the radial direction and a horizontal plate portion 73b extending in the axial direction. There is. The vertical plate portion 73a is arranged apart from the inner end surface of the rear cover 29v, and the vertical plate portion 73a functions as the barrier portion 66. A gap 50 is provided between the vertical plate portion 73a and the outer peripheral surface of the tubular portion 62 (bearing fitting portion 63). A gap 49 is also provided between the lateral plate portion 73b and the inner peripheral surface of the tubular portion of the casing 10 (rear cover 29v).

The wiring fixing member 73 is fixed to the inner end surface of the rear cover 29v by, for example, a bolt 75 penetrating the vertical plate portion 73a. As shown in FIG. 7, a cylindrical mounting portion 74 that receives the shaft portion of the bolt 75 is provided on the inner end surface of the rear cover 29v so as to project. The signal line 81 of the resolver 80 is fixed to the vertical plate portion 73 a of the wiring fixing member 73. A signal line of another type (for example, a signal line extending from an oil temperature sensor (not shown) that detects the temperature of the lubricating oil stored in the oil tank 40) is fixed to the horizontal plate portion 73b of the wiring fixing member 73. May be.

In this case, the lubricating oil that has flowed down between the vertical plate portion 73a of the wire fixing member 73 and the inner end surface of the rear cover 29v forms a gap 49 between the horizontal plate portion 73b and the rear cover 29v or the inner peripheral surface of the motor casing 29. It flows back to the oil tank 40.

As described above, in the present embodiment, since the wiring fixing member 73 also serves as the barrier 66, the number of parts can be suppressed. It should be noted that although the barrier portion 66 is arranged to be spaced apart from the bearing fitting portion 63 (cylindrical portion 62), it may be arranged to be in contact with the bearing fitting portion 63. Further, the barrier portion 66 is not limited to the example formed by a member separate from the casing 10, and may be integrally formed with the casing 10 as shown in FIGS. 5 and 6, for example.

The terminal (not shown) provided at the tip of the signal line 81 is connected to the connector (not shown) provided at the tip of the signal line extending from the vehicle body side at the signal line outlet 72. In this case, the connector is fixed by the connector fixing member 84 shown in FIG. The connector fixing member 84 is formed in an annular shape so as to surround the periphery of the signal line outlet 72, and a through hole for inserting the shaft portion of the bolt 85 into both the vehicle front side and the rear side of the signal line outlet 72. Is provided. The shaft portion of the bolt 85 penetrates the through hole of the connector fixing member 84 and is screwed into a female screw hole provided on the outer end surface (the end surface facing the inner side in the vehicle width direction) of the rear cover 29v. As a result, the connector can be securely fixed to the rear cover 29v.

As described above, according to the present embodiment, by using the sensor chamber S2 that houses the resolver 80 as a bypass path for the lubricating oil, it is possible to prevent the lubricating oil from splashing on the rotor 23. As a result, the rotational resistance of the rotor 23 can be reduced, and the efficiency of the motor unit 21 can be improved.

Further, since at least a part of the bottom surface of the discharge passage 48 is inclined so that the sensor chamber S2 side is downward, the lubricating oil received (recovered) at the protrusion 63p can be efficiently guided to the sensor chamber S2. You can

As shown in FIG. 11, in order to more efficiently guide the lubricating oil received at the protruding portion 63p to the sensor chamber S2, a return portion 67 protruding radially inward is provided at the tip of the protruding portion 63p. May be. The return portion 67 is preferably arranged at least below the axis M and provided so as to intersect the edge of the groove 63b. As a result, even if the lubricating oil received on the inner peripheral surface of the protruding portion 63p tries to flow to the first space S10 side, the lubricating oil is returned by the return portion 67, so that the amount of lubricating oil flowing to the first space S10 is more sufficient. Can be reduced to

Further, since the barrier portion 66 is arranged in the motor chamber S1 so as to face at least a part of the communication hole 71, when the lubricating oil discharged into the sensor chamber S2 returns to the oil tank 40, the lubricating oil It is possible to prevent scattering to the rotor 23.

Further, since the signal line 81 of the resolver 80 is fixed to the barrier section 66, the signal line 81 can be isolated from the rotor 23. As a result, it is possible to prevent the signal line 81 from being caught in the rotor 23 rotating at a high speed and breaking.

In the present embodiment, the example in which the bearing fitting portion 63 is located between the motor chamber S1 and the sensor chamber S2 has been described, but the present invention is not limited to this, and the space other than the motor chamber S1 and the sensor chamber S2 is not limited. It may be located between and. That is, the second space S20 described above may not be included in the sensor chamber S2.

Further, in the present embodiment, of the two rolling

bearings

27 and 28 that rotatably support the motor rotary shaft 22, the lubricating structure of the rolling bearing 28 located on the resolver 80 side has been described. The rolling bearing 27 may have the same lubrication structure.

The embodiments disclosed this time are to be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description but by the claims, and is intended to include meanings equivalent to the claims and all modifications within the scope.

1,100 in-wheel motor drive device, 10 casing, 11 wheel hub bearing part, 21 motor part, 22 motor rotating shaft, 23 rotor, 23a rotor core, 23b rotor support part, 24 stator, 27,28 rolling bearing, 29 motor casing , 29v rear cover, 31 speed reducer, 39 speed reducer casing, 40 oil tank, 43 oil pump, 45 oil passage, 47 supply path, 48 discharge path, 61, 63, 163 bearing fitting part, 62, 162 tubular part, 63b groove, 63p protruding part, 64 partition wall part, 64b discharge hole, 65 sensor fitting part, 66 barrier part, 67 return part, 71 communication hole, 72 signal line outlet, 73 wiring fixing member, 80 resolver, 81 signal line , 82 fixing member, 82b notch, S Motor chamber, S2 sensor chamber, S3 deceleration chamber, S10 first space, S20 second space, W wheel.

Claims

An in-wheel motor drive arranged in the wheel of the wheel,
A motor unit including a rotor, a motor rotating shaft that rotates integrally with the rotor, and a rolling bearing that rotatably supports an axial end portion of the motor rotating shaft,
A casing that houses the motor unit,
A bearing fitting portion which is provided in the casing and is located between the first space on the rotor side and the second space on the opposite side, which are axially separated from each other, and into which the rolling bearing is fitted. Prepare,
The bearing fitting portion projects toward the first space beyond the position of the end surface of the rolling bearing arranged to face the first space, and receives the lubricating oil supplied to the rolling bearing. Has
The in-wheel motor drive device, wherein a discharge passage for discharging the lubricating oil received by the protrusion to the second space is formed in the bearing fitting portion.
In the bearing fitting portion, a supply path for supplying lubricating oil from above to the rolling bearing is formed,
The in-wheel motor drive device according to claim 1, wherein the discharge path is disposed below an axis of the motor rotation shaft.
The in-wheel motor drive device according to claim 2, wherein the bottom surface of the discharge path is inclined so that the second space side is lower than the first space side.
The rotor includes a rotor core and a rotor support portion that supports the rotor core,
The in-wheel motor drive device according to any one of claims 1 to 3, wherein at least a part of the rolling bearing overlaps an axial position of the rotor.
The first space is included in a motor chamber in which a central portion of the rotor and the motor rotation shaft is arranged,
The in-wheel motor drive device according to any one of claims 1 to 4, wherein the second space is included in a sensor chamber in which a rotation sensor that detects rotation of the motor rotation shaft is arranged.
Further comprising a partition wall portion arranged between the bearing fitting portion and the sensor chamber,
The in-wheel motor drive device according to claim 5, wherein the discharge passage includes a groove formed on an inner peripheral surface of the bearing fitting portion and a discharge hole that axially penetrates the partition wall portion.
The in-wheel motor drive device according to claim 6, wherein a return portion arranged so as to intersect with the groove is provided at a tip of the protruding portion.
The said rotation sensor is being fixed to the end surface of the said partition part by the substantially C-shaped fixing member arrange | positioned so that a notch may be located in the part of the said discharge hole, The Claim 6 or 7 of Claim 7. In-wheel motor drive.
A communication hole that communicates the motor chamber and the sensor chamber is provided at a position lower than the discharge path,
9. The motor chamber is provided with a barrier portion for preventing the lubricating oil returned from the sensor chamber through the communication hole and returned to the motor chamber from scattering to the rotor. In-wheel motor drive described.
The in-wheel motor drive device according to claim 9, wherein a signal line of the rotation sensor is fixed to the barrier portion.