JP2016070294A - In-wheel motor drive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an in-wheel motor drive showing superior quietness and durability in which vibration or noise generated at a speed reducer is reduced.SOLUTION: This invention relates to an in-wheel motor drive 21 constituted by a motor part A, a speed reducer part B, and a wheel bearing part C. The speed reducer part B has a speed reducer input shaft 25 having eccentric parts 25a, 25b and rotationally driven by the motor part A; curved line plates 26a, 26b rotatably held at the outer peripheries of the eccentric parts 25a, 25b through a cylindrical roller bearing 41 so as to perform a revolving motion around a center of its rotating axial center as the speed reducer input shaft 25 is rotated; and a motion converting mechanism for converting a rotation movement generated at the curved line plates 26a, 26b during the revolving motion into a rotating motion of a speed reducer output shaft 28. The cylindrical roller 44 constituting the cylindrical roller bearing 41 has a crowning processing at its outer peripheral surface.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an in-wheel motor drive device in which, for example, an output shaft of an electric motor and a wheel bearing are connected via a reduction gear.

  A conventional in-wheel motor drive device has a structure disclosed in Patent Document 1, for example. The in-wheel motor driving device disclosed in Patent Document 1 includes a motor unit that generates a driving force inside a casing that is attached to a vehicle body via a suspension device (suspension), and a wheel bearing unit that is connected to a wheel. And a speed reducer unit that is disposed between the motor unit and the wheel bearing unit and decelerates the rotation of the motor unit and transmits it to the wheel bearing unit.

  In the in-wheel motor drive device having the above-described configuration, a small motor with low torque and high speed rotation is adopted for the motor unit from the viewpoint of compactness of the device. On the other hand, since a large torque is required to drive the wheel by the wheel bearing portion, a cycloid reduction gear that is compact and obtains a high reduction ratio is employed for the reduction gear portion.

  The speed reducer part employing this cycloid speed reducer has a pair of eccentric parts, and is rotated via a rolling bearing on the outer periphery of the speed reducer input shaft rotated by the motor part and the eccentric part of the speed reducer input shaft. A pair of curved plates held freely, a plurality of outer pins that engage with the outer peripheral surface of the curved plate and cause the curved plate to rotate, and an inner peripheral surface of the through hole of the curved plate The main part is composed of a plurality of inner pins that transmit the rotation of the plate to the output shaft of the reduction gear.

  In the reducer part that constitutes this in-wheel motor drive device, the reducer input shaft is driven at high speed by the motor part, and a large load (radial load or moment load) is repeatedly applied to the rolling bearing through a curved plate or the like. Be loaded. Therefore, as the rolling bearing, a cylindrical roller bearing that can cope with high-speed rotation and is excellent in load carrying capacity is adopted.

JP 2012-148725 A

  In order to realize a lightweight and compact in-wheel motor drive device, the applicant of the present application is particularly interested in downsizing the components of the speed reducer, and in particular, a rolling bearing (cylindrical roller bearing) that holds a curved plate rotatably. Focused on. That is, it is preferable to reduce the size of the cylindrical roller bearing in order to suppress the amount of heat generated inside the bearing accompanying the high speed rotation of the reduction gear input shaft and to prevent the occurrence of seizure as much as possible.

  However, a large load is repeatedly applied from the curved plate to the cylindrical roller bearing that rotatably supports the curved plate as the reduction gear input shaft rotates. That is, in order to smoothly rotate and rotate the curved plate, the curved plate is provided with an axial backlash of about 1.5 mm. This axial backlash may cause misalignment such as tilt in the curved plate.

  In that case, the cylindrical roller bearing is in a state where a radial load or a moment load is applied from the curved plate and an excessive stress is easily generated. Under such circumstances, a local excessive load is applied to the end of the cylindrical roller bearing. As a result, the bearing life is reduced, and sound and vibration due to the contact between the curved plate and the cylindrical roller bearing are generated.

  Accordingly, the present invention has been proposed in view of the above-mentioned problems, and the object of the present invention is to reduce the vibration and noise generated in the speed reducer, and to drive an in-wheel motor excellent in quietness and durability. To provide an apparatus.

  As technical means for achieving the above-mentioned object, the present invention is an in-wheel motor drive device comprising a motor part, a reduction gear part and a wheel bearing part, and the reduction gear part has an eccentric part. A reduction gear input shaft that is rotationally driven by the motor unit, and a revolving motion centered on the rotation shaft center with the rotation of the reduction gear input shaft that is rotatably held on the outer periphery of the eccentric portion via a rolling bearing. The roller that constitutes the rolling bearing is crowned on the outer peripheral surface of the roller plate. It is characterized by.

  In the present invention, by applying crowning to the outer peripheral surface of the roller of the rolling bearing that rotatably holds the curved plate, radial stress or moment load is applied due to misalignment such as inclination of the curved plate and excessive stress is generated. Even in a situation where it is easy to do, a local excessive load is hardly generated at the roller end. Further, it is possible to suppress the sound and vibration caused by the contact with the curved plate, and to prevent the roller from being damaged in advance and to ensure the bearing life. As a result, it is possible to reduce the vibration and noise generated in the speed reducer, and to realize an in-wheel motor drive device that is excellent in silence and durability.

  The roller in the present invention is preferably crowned with a radial displacement of 2 to 15 μm at a measurement point located 1.5 mm inward in the axial direction from the end face. In this way, it is possible to realize a roller having an optimum crowning. As a result, it is possible to reliably suppress the occurrence of a local excessive load based on the misalignment of the curved plate at the roller end portion. In addition, sound and vibration due to contact with the curved plate can be reliably suppressed, and the bearing life can be improved.

  As the rolling bearing in the present invention, an inner raceway surface formed on the outer periphery of the inner ring mounted on the outer periphery of the speed reducer input shaft, an outer raceway surface formed on the inner periphery of the curved plate, and interposed between both raceway surfaces. A cylindrical roller bearing composed of a plurality of cylindrical rollers and a cage that holds the cylindrical rollers is suitable.

  According to the present invention, a local excessive load at the roller end portion is generated even in a situation where a radial load or a moment load is applied and an excessive stress is likely to occur due to misalignment such as the inclination of the curved plate. It becomes difficult. Further, it is possible to suppress the sound and vibration caused by the contact with the curved plate, and to prevent the roller from being damaged in advance and to ensure the bearing life. As a result, it is possible to reduce the vibration and noise generated in the speed reducer, and to realize an in-wheel motor drive device that is excellent in silence and durability.

1 is a longitudinal sectional view showing an overall configuration of an in-wheel motor drive device in an embodiment of the present invention. It is sectional drawing which follows the PP line | wire of FIG. It is a principal part expanded sectional view which shows the reduction gear part of FIG. It is explanatory drawing which shows the load which acts on the curve board of FIG. It is a cross-sectional view which shows the rotary pump of FIG. It is a principal part expanded sectional view which shows the cylindrical roller bearing which hold | maintains the curve board of FIG. 1 rotatably. It is a principal part expanded sectional view which shows the cylindrical roller in the cylindrical roller bearing of FIG. It is a top view which shows schematic structure of the electric vehicle carrying an in-wheel motor drive device. FIG. 9 is a rear sectional view showing the electric vehicle of FIG. 8.

  An embodiment of an in-wheel motor drive device according to the present invention will be described in detail with reference to the drawings.

  FIG. 8 is a schematic plan view of the electric vehicle 11 on which the in-wheel motor drive device 21 is mounted, and FIG. 9 is a schematic cross-sectional view of the electric vehicle 11 as viewed from the rear. As shown in FIG. 8, the electric vehicle 11 includes a chassis 12, a front wheel 13 as a steering wheel, a rear wheel 14 as a drive wheel, and an in-wheel motor drive device 21 that transmits driving force to the rear wheel 14. Equip. As shown in FIG. 9, the rear wheel 14 is accommodated in the wheel housing 12a of the chassis 12, and is fixed to the lower portion of the chassis 12 via a suspension device (suspension) 12b.

  The suspension device 12b supports the rear wheel 14 by a suspension arm extending left and right, and suppresses vibration of the chassis 12 by absorbing vibration received by the rear wheel 14 from the ground by a strut including a coil spring and a shock absorber. Furthermore, a stabilizer that suppresses the inclination of the vehicle body when turning, etc., is provided at the connecting portion of the left and right suspension arms. The suspension device 12b is an independent suspension type in which the left and right wheels can be moved up and down independently in order to improve the followability to the road surface unevenness and efficiently transmit the driving force of the rear wheel 14 to the road surface.

  The electric vehicle 11 is provided with the in-wheel motor drive device 21 that drives the left and right rear wheels 14 inside the wheel housing 12a, thereby eliminating the need to provide a motor, a drive shaft, a differential gear mechanism, and the like on the chassis 12. . As a result, there is an advantage that a wide cabin space can be secured and the rotation of the left and right rear wheels 14 can be controlled. In order to improve the running stability and NVH characteristics of the electric vehicle 11, it is necessary to suppress the unsprung weight. Furthermore, the in-wheel motor drive device 21 is required to be downsized in order to secure a large cabin space.

  Therefore, the in-wheel motor drive device 21 of this embodiment has the following structure. 1 is a longitudinal sectional view showing a schematic configuration of an in-wheel motor drive device 21, FIG. 2 is a sectional view taken along the line P-P in FIG. 1, FIG. 3 is an enlarged sectional view showing a reduction gear portion B, and FIG. FIG. 5 is a cross-sectional view showing the rotary pump 51. FIG. 5 is an explanatory view showing the load acting on the plate 26a. Before describing the characteristic configuration of this embodiment, the overall configuration of the in-wheel motor drive device 21 will be described.

  As shown in FIG. 1, the in-wheel motor drive device 21 includes a motor part A that generates a driving force, a speed reducer part B that decelerates and outputs the rotation of the motor part A, and an output from the speed reducer part B. And a wheel bearing portion C that transmits to a rear wheel 14 (see FIGS. 8 and 9) as a drive wheel. The motor part A and the speed reducer part B are accommodated in the casing 22 and attached to the wheel housing 12a (see FIG. 9) of the electric vehicle 11. The casing 22 is a divided structure including a motor housing in which the motor part A is accommodated and a speed reducer housing in which the speed reducer part B is accommodated, and is fastened and integrated by bolts.

  The motor portion A is a stator 23a fixed to the casing 22, a rotor 23b disposed to face the inner side in the radial direction of the stator 23a with a gap, and a radial inner side of the rotor 23b so as to rotate integrally with the rotor 23b. A radial gap motor including a motor rotating shaft 24. The stator 23a is configured by winding a coil 23d around the outer periphery of a magnetic core 23c, and the rotor 23b is configured by a permanent magnet or a magnetic material.

  The motor rotating shaft 24 has a rotor 23b held by a holder portion 24d that extends integrally outward in the radial direction. The holder portion 24d has a configuration in which a concave groove in which the rotor 23b is fitted and fixed is formed in an annular shape. The motor rotating shaft 24 is rotatable with respect to the casing 22 by one end in the axial direction (right side in FIG. 1) on the rolling bearing 36a and the other end in the axial direction (left side in FIG. 1) by the rolling bearing 36b. It is supported by.

  The reduction gear input shaft 25 has a substantially central portion on the one side in the axial direction (right side in FIG. 1) as a rolling bearing 37a and an end portion on the other side in the axial direction (left side in FIG. 1) as a rolling bearing 37b. Is supported so as to be freely rotatable. The reduction gear input shaft 25 has eccentric portions 25 a and 25 b in the reduction gear portion B. The two eccentric portions 25a and 25b are provided with a 180 ° phase shift in order to cancel the centrifugal force due to the eccentric motion. The reduction gear input shaft 25 and the above-described motor rotation shaft 24 are connected by spline fitting, and the driving force of the motor part A is transmitted to the reduction gear part B.

  The reducer portion B includes curved plates 26a and 26b that are rotatably held by the eccentric portions 25a and 25b of the reducer input shaft 25, and a plurality of outer pins 27 that engage with the outer peripheral portions of the curved plates 26a and 26b. And a motion conversion mechanism for transmitting the rotational motion of the curved plates 26a and 26b to the speed reducer output shaft 28, and a counterweight 29 provided on the speed reducer input shaft 25 adjacent to the eccentric portions 25a and 25b.

  The reduction gear output shaft 28 has a flange portion 28a and a shaft portion 28b. A plurality of inner pins 31 are fixed to the flange portion 28a at equal intervals on a circumference centered on the rotational axis of the reduction gear output shaft 28. The shaft portion 28 b is connected to a hub wheel 32 as an inner member of the wheel bearing portion C so as to be able to transmit torque by spline fitting, and transmits the output of the speed reducer portion B to the rear wheel 14. The reduction gear output shaft 28 is rotatably supported on the outer pin housing 60 by a rolling bearing 46.

  As shown in FIGS. 2 and 3, the curved plates 26 a and 26 b have a plurality of corrugations composed of trochoidal curves such as epitrochoids on the outer periphery, and through holes that penetrate from one end face to the other end face 30a and 30b. A plurality of through holes 30a are provided at equal intervals on the circumference centered on the rotation axis of the curved plates 26a, 26b, and receive the inner pin 31 described above. Further, the through hole 30b is provided at the center of the curved plates 26a and 26b and is fitted to the eccentric portions 25a and 25b. The curved plates 26a and 26b are rotatably supported with respect to the eccentric portions 25a and 25b by a cylindrical roller bearing 41 which is a rolling bearing.

  The outer pins 27 are provided at equal intervals on a circumference centered on the rotational axis of the speed reducer input shaft 25. When the curved plates 26a and 26b revolve, the curved waveform and the outer pin 27 are engaged to cause the curved plates 26a and 26b to rotate. The outer pin 27 is rotatably held by the outer pin housing 60 by a needle roller bearing 27a. Thereby, the contact resistance between the curved plates 26a and 26b can be reduced. The outer pin housing 60 is prevented from rotating with respect to the casing 22 and is supported in a floating state.

As shown in FIG. 3, the counterweight 29 has a through hole that engages with the speed reducer input shaft 25 to counteract the unbalanced inertia couple generated by the rotation of the curved plates 26a and 26b. The eccentric portions 25a and 25b are arranged 180 ° out of phase with each other at positions adjacent to the eccentric portions 25a and 25b. Assuming that the center point in the rotational axis direction between the two curved plates 26a, 26b is G, the distance between the center point G and the center of the curved plate 26a is L ₁ , and the curved plate 26a, The sum of the masses of the rolling bearing 41 and the eccentric portion 25a is m ₁ , the eccentric amount of the center of gravity of the curved plate 26a from the rotational axis is ε ₁ , the distance between the center point G and the counter weight 29 is L ₂ , and the counter weight 29 mass m ₂ of the eccentricity amount from the rotation axis of the center of gravity of the counterweight 29 and epsilon _2, and has a relationship that satisfies _{L 1 × m 1 × ε 1} = L 2 × m 2 × ε 2. The relationship of L ₁ × m ₁ × ε ₁ = L ₂ × m ₂ × ε ₂ allows errors that inevitably occur. A similar relationship is established between the curved plate 26 b on the left side of the center point G and the counterweight 29.

  The motion conversion mechanism includes a plurality of inner pins 31 that are held by the reduction gear output shaft 28 and extend in the axial direction, and through holes 30a provided in the curved plates 26a and 26b. The inner pins 31 are provided at equal intervals on the circumference centering on the rotational axis of the reduction gear output shaft 28, and one axial end thereof is fixed to the flange 28 a of the reduction gear output shaft 28. Yes. Further, in order to reduce the frictional resistance with the curved plates 26a, 26b, needle roller bearings 31a are provided at positions where they contact the inner wall surfaces of the through holes 30a of the curved plates 26a, 26b. The through hole 30a is provided at a position corresponding to each of the plurality of inner pins 31, and the inner diameter dimension of the through hole 30a is set larger than the outer diameter dimension of the inner pin 31 (the maximum outer diameter including the needle roller bearing 31a). ing.

  A stabilizer 31 b is provided at the other axial end of the inner pin 31. The stabilizer 31b includes an annular ring portion 31c and a cylindrical portion 31d extending in the axial direction from the inner peripheral surface of the annular portion 31c. The ends on the other axial side of the plurality of inner pins 31 are fixed to the annular portion 31c. Since the load applied to some of the inner pins 31 from the curved plates 26a, 26b is supported by all the inner pins 31 via the flanges 28a and the stabilizers 31b, the stress acting on the inner pins 31 is reduced, and the durability is improved. Can be improved.

The state of the load acting on the curved plates 26a and 26b will be described with reference to FIG. The shaft center O ₂ of the eccentric portion 25 a is eccentric from the shaft center O of the reduction gear input shaft 25 by the amount of eccentricity e. The outer periphery of the eccentric portion 25a is attached is curved plates 26a, the eccentric part 25a is so rotatably supports the curve plate 26a, the axial center O ₂ is also the axis of the curved plate 26a. The outer periphery of the curved plate 26a is formed by a corrugated curve, and has corrugated concave portions 26c that are depressed in the radial direction at equal intervals in the circumferential direction. Around the curved plate 26a, a plurality of outer pins 27 that engage with the recesses 26c are arranged in the circumferential direction around the axis O.

  In FIG. 4, when the eccentric part 25a rotates counterclockwise on the paper surface together with the speed reducer input shaft 25, the eccentric part 25a performs a revolving motion around the axis O, so that the concave part 26c of the curved plate 26a The pin 27 is sequentially brought into contact with the circumferential direction. As a result, as indicated by the arrow, the curved plate 26a receives the load Fi from the plurality of outer pins 27 and rotates clockwise.

Further, the curved plates 26a through hole 30a has a plurality circumferentially disposed about the axis O _2. An inner pin 31 that is coupled to the reduction gear output shaft 28 that is disposed coaxially with the axis O is inserted through each through hole 30a. Since the inner diameter of the through-hole 30a is larger than the outer diameter of the inner pin 31, the inner pin 31 does not hinder the revolving motion of the curved plate 26a, and the inner pin 31 extracts the rotational motion of the curved plate 26a. The reduction gear output shaft 28 is rotated. At this time, the speed reducer output shaft 28 has a higher torque and a lower rotational speed than the speed reducer input shaft 25, and the curved plate 26a receives the load Fj from the plurality of inner pins 31 as indicated by arrows in FIG. . The resultant force Fs of the plurality of loads Fi and Fj is applied to the speed reducer input shaft 25.

The direction of the resultant force Fs changes depending on geometrical conditions such as the corrugated shape of the curved plate 26a, the number of concave portions 26c, and the influence of centrifugal force. Specifically, the angle α between the reference line X perpendicular to the straight line Y connecting the rotation axis O ₂ and the axis O and passing through the rotation axis O ₂ and the resultant force Fs is approximately 30 ° to 60 °. It fluctuates with. The directions and magnitudes of the loads Fi and Fj change during one rotation (360 °) of the speed reducer input shaft 25. As a result, the resultant force Fs acting on the speed reducer input shaft 25 is also different from the direction of the load. The size varies. When the speed reducer input shaft 25 rotates once counterclockwise, the corrugated concave portion 26c of the curved plate 26a is decelerated and rotated clockwise by one pitch to the state shown in FIG. 4, and this is repeated.

  As shown in FIG. 1, the wheel bearing 33 of the wheel bearing portion C is fitted to a hub wheel 32 in which an inner raceway surface 33 f is directly formed on the outer peripheral surface and a small diameter step portion 32 a on the outer peripheral surface of the hub wheel 32. The inner ring 33a having the inner raceway surface 33g formed on the outer peripheral surface constitutes an inner member, fitted and fixed to the inner peripheral surface of the casing 22, and outer raceway surfaces 33h and 33i are formed on the inner peripheral surface. The distance between the adjacent balls 33c and the plurality of balls 33c as rolling elements arranged between the outer ring 33b, the inner raceway surfaces 33f and 33g of the hub ring 32 and the inner ring 33a and the outer raceway surfaces 33h and 33i of the outer ring 33b. This is a double-row angular contact ball bearing provided with a retainer 33d to be held and seal members 33e for sealing both axial ends of the wheel bearing 33. The rear wheel 14 (see FIGS. 8 and 9) is connected and fixed to the hub wheel 32 of the wheel bearing 33 by bolts 34.

  Next, the overall lubrication mechanism will be described. This lubricating mechanism supplies lubricating oil to the motor part A and cools the reducing part B to cool the motor part A. As shown in FIG. 1, the lubrication mechanism includes a rotary pump 51, oil passages 22a, 24a, 24b and an oil hole 24c provided in the motor part A, an oil passage 25c provided in the reduction gear part B, and The oil holes 25d and 25e and the oil tank 22d disposed below the casing 22 are mainly configured.

  The oil passage 22a provided in the casing 22 extends radially outward from the rotary pump 51, is bent, extends in the axial direction, is further bent, extends radially inward, and is connected to the oil passage 24a. The oil passage 24a extends along the axial direction inside the motor rotating shaft 24 and is connected to the oil passage 25c. The oil passage 24b of the motor rotating shaft 24 communicates with the oil passage 24a extending along the axial direction, and extends toward the holder portion 24d located on the radially outer side to communicate with the oil hole 24c. The oil hole 24c is formed in the end face of the holder part 24d on the inboard side and the outboard side, and opens into the motor part A.

  The oil passage 25c extends along the axial direction inside the reduction gear input shaft 25. The oil hole 25d communicates with an oil passage 25c extending along the axial direction, extends in the radial direction on the outer peripheral surface of the speed reducer input shaft 25, and opens inside the speed reducer portion B. The oil hole 25e communicates with an oil passage 25c extending along the axial direction, and opens from the shaft end of the speed reducer input shaft 25 to the inside of the speed reducer part B.

  Between the motor part A and the speed reducer part B of the casing 22, an oil passage 22b communicating with the inside of the motor part A and the inside of the speed reducer part B is provided, and the bottom part of the casing 22 at the position of the motor part A Is provided with an oil passage 22f for discharging the lubricating oil inside the motor part A to the oil tank 22d. Further, an oil passage 22 e for returning the lubricating oil from the oil tank 22 d to the rotary pump 51 is provided in the casing 22. The rotary pump 51 for forcibly circulating the lubricating oil is provided between the oil passage 22e and the oil passage 22a of the casing 22.

  As shown in FIG. 5, the rotary pump 51 includes an inner rotor 52 that rotates using the rotation of the speed reducer output shaft 28 (see FIG. 1), an outer rotor 53 that rotates following the rotation of the inner rotor 52, and a pump chamber. 54, a cycloid pump including a suction port 55 communicating with the oil passage 22e and a discharge port 56 communicating with the oil passage 22a. By disposing the rotary pump 51 in the casing 22, it is possible to prevent the in-wheel motor drive device 21 from becoming large.

  The inner rotor 52 has a tooth profile formed of a cycloid curve on the outer peripheral surface. Specifically, the shape of the tooth tip portion 52a is an epicycloid curve, and the shape of the tooth gap portion 52b is a hypocycloid curve. The inner rotor 52 is fitted to the outer peripheral surface of a cylindrical portion 31d (see FIGS. 1 and 3) provided in the stabilizer 31b and rotates integrally with the speed reducer output shaft 28. The outer rotor 53 has a tooth profile formed of a cycloid curve on the inner peripheral surface. Specifically, the shape of the tooth tip portion 53a is a hypocycloid curve, and the shape of the tooth gap portion 53b is an epicycloid curve. The outer rotor 53 is rotatably supported by the casing 22.

The inner rotor 52 rotates about the rotation center c ₁ , while the outer rotor 53 rotates about the rotation center c ₂ . Since the inner rotor 52 and the outer rotor 53 rotate about different rotation centers c ₁ and c ₂ , the volume of the pump chamber 54 changes continuously. As a result, the lubricating oil flowing in from the suction port 55 is pumped from the discharge port 56 to the oil passage 22a.

  The flow of the lubricating oil by the lubricating mechanism having the above-described configuration will be described. In FIG. 1, the white arrow given in the lubrication mechanism indicates the flow of the lubricating oil. As the cooling of the motor part A, the lubricating oil pumped from the rotary pump 51 passes through the oil passages 22a and 24a, and a part of the lubricating oil passes through the oil passage 24b by the centrifugal force and the pump pressure accompanying the rotation of the motor rotating shaft 24. 23b is cooled. Furthermore, lubricating oil is discharged from the oil holes 24c of the holder portion 24d to cool the stator 23a. In this way, the motor part A is cooled.

  On the other hand, as lubrication of the speed reducer part B, the lubricating oil pumped from the rotary pump 51 passes through the oil passages 22a, 24a, 25c, and a part thereof is caused by the centrifugal force and the pump pressure accompanying the rotation of the speed reducer input shaft 25. The oil is discharged from the oil holes 25d and 25e to the speed reducer part B. The lubricating oil discharged from the oil hole 25d is supplied into the bearing from an oil hole 42c (see FIG. 3) provided in the inner ring 42 of the cylindrical roller bearing 41 that supports the curved plates 26a and 26b. Furthermore, it moves radially outward via an oil passage 60a provided in the outer pin housing 60 while lubricating the contact portions of the curved plates 26a, 26b with the inner pins 31 and the outer pins 27, and the like. The lubricating oil discharged from the oil hole 25e is supplied to a rolling bearing 37b that supports the speed reducer input shaft 25 and the like. In this way, the reduction gear part B is lubricated.

  The lubricating oil that has cooled the motor part A and lubricated and cooled the speed reducer part B travels along the inner wall surface of the casing 22 and moves downward by gravity. The lubricating oil that has moved to the lower part of the speed reducer part B moves from the oil passage 22b to the motor part A. The lubricating oil that has moved to the lower part of the motor part A is discharged from the oil passage 22f together with the lubricating oil from the speed reducer part B, and is temporarily stored in the oil tank 22d. Thus, since the oil tank 22d is provided, even if lubricating oil that cannot be completely discharged by the rotary pump 51 is temporarily generated, it can be stored in the oil tank 22d. As a result, an increase in torque loss of the reduction gear unit B can be prevented.

  The overall configuration of the in-wheel motor drive device 21 in this embodiment is as described above, and the characteristic configuration will be described in detail below.

  As shown in FIG. 6, the cylindrical roller bearing 41 that rotatably supports the curved plates 26a, 26b is fitted to the outer peripheral surfaces of the eccentric portions 25a, 25b, and the inner ring 42 in which the inner raceway surface 42a is formed on the outer peripheral surface. And an outer raceway surface 43 (see FIGS. 2 and 3) directly formed on the inner circumferential surface of the through hole 30b of the curved plates 26a and 26b, and a plurality disposed between the inner raceway surface 42a and the outer raceway surface 43. The cylindrical roller 44 and a retainer 45 for holding the cylindrical roller 44 are provided. The inner ring 42 has flanges 42b that protrude radially outward from both axial ends of the inner raceway surface 42a.

  As shown in FIG. 7, this cylindrical roller bearing 41 has a measuring point GP of 2 to 15 μm at an outer peripheral surface 44a of the cylindrical roller 44 at a position 1.5 mm (= M) axially inward from the roller end surface 44b. Crowning (crowning length CL, crowning radius CR) having a radial displacement amount N is applied. In addition, the axial direction center part (part | part except crowning length CL of both ends) of the outer peripheral surface 44a of this cylindrical roller 44 is made into the flat surface parallel to an axial direction. The axial dimension (for example, 11 mm) of the cylindrical roller 44 is set to be larger than the axial dimension (for example, 8 mm) of the curved plates 26a and 26b.

  In the reducer portion B, in order to smoothly rotate and rotate the curved plates 26a and 26b, the curved plates 26a and 26b are provided with an axial backlash of about 1.5 mm. This axial backlash may cause misalignment such as tilt in the curved plates 26a and 26b. In the cylindrical roller bearing 41, crowning is performed on the outer peripheral surface 44 a of the cylindrical roller 44 even under a situation where radial stress or moment load is easily applied due to misalignment such as inclination of the curved plates 26 a and 26 b. By giving, it becomes difficult to generate the local excessive load in a roller edge part. Further, the sound and vibration caused by the contact between the curved plates 26a and 26b and the cylindrical roller 44 can be suppressed, and the cylindrical roller 44 can be prevented from being damaged and the bearing life can be ensured. As a result, it is possible to reduce the vibration and noise generated in the speed reducer B, and to realize the in-wheel motor drive device 21 that is excellent in silence and durability.

  In the crowning of the outer peripheral surface 44a of the cylindrical roller 44, if the aforementioned amount of radial displacement is smaller than 2 μm, local overload at the end of the cylindrical roller 44 during misalignment load such as the inclination of the curved plates 26a and 26b. A load is easily generated. Conversely, if the radial displacement is larger than 15 μm, the posture of the cylindrical roller 44 becomes unstable, leading to the generation of sound and vibration. In FIG. 7, the crowning is exaggerated.

  Finally, the overall operation principle of the in-wheel motor drive device 21 in this embodiment will be described.

  As shown in FIGS. 1 to 3, the motor unit A receives, for example, an electromagnetic force generated by supplying an alternating current to the coil of the stator 23 a, and the rotor 23 b made of a permanent magnet or a magnetic body rotates. . Thereby, when the reduction gear input shaft 25 connected to the motor rotation shaft 24 rotates, the curved plates 26 a and 26 b revolve around the rotation axis of the reduction gear input shaft 25. At this time, the outer pin 27 engages with the curved waveform of the curved plates 26 a and 26 b to rotate the curved plates 26 a and 26 b in the direction opposite to the rotation of the speed reducer input shaft 25.

  The inner pin 31 inserted through the through hole 30a comes into contact with the inner wall surface of the through hole 30a as the curved plates 26a and 26b rotate. As a result, the revolving motion of the curved plates 26 a and 26 b is not transmitted to the inner pin 31, and only the rotational motion of the curved plates 26 a and 26 b is transmitted to the wheel bearing portion C via the reduction gear output shaft 28. At this time, since the rotation of the speed reducer input shaft 25 is decelerated by the speed reducer portion B and transmitted to the speed reducer output shaft 28, even when the low torque, high speed type motor portion A is employed, the rear wheel 14 The necessary torque can be transmitted.

The reduction ratio of the reduction gear part B is calculated as (Z _A −Z _B ) / Z _B where Z _{A is} the number of outer pins 27 and Z _B is the number of waveforms of the curved plates 26a and 26b. In the embodiment shown in FIG. 2, since Z _A = 12 and Z _B = 11, a very large reduction ratio of 1/11 can be obtained. Thus, by adopting the reduction gear unit B that can obtain a large reduction ratio without using a multistage configuration, a compact and high reduction ratio in-wheel motor drive device 21 can be obtained. Further, since the needle roller bearings 27a and 31a (see FIG. 3) are provided on the outer pin 27 and the inner pin 31, the frictional resistance between the curved plates 26a and 26b is reduced. Transmission efficiency is improved.

  In this embodiment, the oil passage 24b is provided in the motor rotating shaft 24, the oil hole 25d is provided in the eccentric portions 25a and 25b, and the oil hole 25e is provided in the shaft end of the speed reducer input shaft 25. However, the present invention is not limited to this, and the motor rotation shaft 24 and the reduction gear input shaft 25 can be provided at arbitrary positions. Moreover, although the example of the cycloid pump was shown as the rotary pump 51, not only this but the rotary pump driven using the rotation of the reduction gear output shaft 28 is employable. Further, the rotary pump 51 may be omitted, and the lubricating oil may be circulated only by centrifugal force.

  The example in which two curved plates 26a and 26b of the speed reducer part B are provided with a 180 ° phase shift has been shown. However, the number of curved plates can be arbitrarily set. For example, when three curved plates are provided. May be provided with a 120 ° phase shift. Although the motion conversion mechanism has shown the example comprised by the inner pin 31 fixed to the reduction gear output shaft 28, and the through-hole 30a provided in the curve boards 26a and 26b, it was not restricted to this but a reduction gear It is possible to adopt an arbitrary configuration that can transmit the rotation of the part B to the hub wheel 32. For example, it may be a motion conversion mechanism constituted by an inner pin fixed to the curved plates 26a and 26b and a hole formed in the reduction gear output shaft 28.

  The description of the operation in this embodiment has been made by paying attention to the rotation of each member, but in reality, power including torque is transmitted from the motor part A to the rear wheel 14. Therefore, the power decelerated as described above is converted to high torque. Also, the case where power is supplied to the motor unit A to drive the motor unit and the power from the motor unit A is transmitted to the rear wheels 14 is shown. On the contrary, the vehicle decelerates or goes down the hill. In such a case, the power from the rear wheel 14 side may be converted into high-rotation low-torque rotation by the reduction gear part B and transmitted to the motor part A, and the motor part A may generate power. Furthermore, the electric power generated here may be stored in a battery and used later for driving the motor unit A or for operating other electric devices provided in the vehicle.

  In this embodiment, although the example which employ | adopted the radial gap motor as the motor part A was shown, the motor of arbitrary structures is applicable not only to this. For example, it may be an axial gap motor including a stator fixed to the casing and a rotor disposed at a position facing the stator with an axial gap inside the stator. Further, although the electric vehicle 11 shown in FIGS. 8 and 9 shows an example in which the rear wheel 14 is a drive wheel, the present invention is not limited to this, and the front wheel 13 may be a drive wheel and is a four-wheel drive vehicle. May be. In the present specification, “electric vehicle” is a concept including all vehicles that obtain driving force from electric power, and should be understood as including, for example, a hybrid vehicle.

  The present invention is not limited to the above-described embodiments, and can of course be implemented in various forms without departing from the gist of the present invention. It includes the equivalent meanings recited in the claims and the equivalents recited in the claims, and all modifications within the scope.

DESCRIPTION OF SYMBOLS 21 In-wheel motor drive device 25 Reduction gear input shaft 25a, 25b Eccentric part 26a, 26b Curve board 28 Reduction gear output shaft 41 Rolling bearing (cylindrical roller bearing)
42 Inner ring 42a Inner raceway surface 43 Outer raceway surface 44 Roller (cylindrical roller)
44a Outer peripheral surface 45 Cage A Motor part B Reducer part C Wheel bearing part

Claims (3)

An in-wheel motor drive device comprising a motor part, a reduction gear part and a wheel bearing part,
The speed reducer part has an eccentric part, and the speed reducer input shaft that is rotationally driven by the motor part is rotatably held on the outer periphery of the eccentric part via a rolling bearing, and the speed reducer input shaft rotates. With a curved plate that performs a revolving motion around its rotational axis, and a motion conversion mechanism that converts the rotational motion that occurs in the curved plate during revolving operation into the rotational motion of the reducer output shaft,
An in-wheel motor drive device characterized in that the roller constituting the rolling bearing has a crowned outer peripheral surface.   2. The in-wheel motor drive device according to claim 1, wherein the roller is crowned with a radial displacement of 2 to 15 μm at a measurement point located 1.5 mm inward in the axial direction from the end face.   The rolling bearing includes an inner raceway surface formed on an outer periphery of an inner ring mounted on an outer periphery of the speed reducer input shaft, an outer raceway surface formed on an inner periphery of the curved plate, and a plurality of intervening surfaces between both raceway surfaces. The in-wheel motor drive device of Claim 1 or 2 comprised by the cylindrical roller and the holder | retainer which hold | maintains the said cylindrical roller.

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