JP6396173B2 - In-wheel motor drive device - Google Patents

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 drive device disclosed in Patent Document 1 is disposed between a motor unit that generates a driving force, a wheel bearing unit connected to a wheel, and the motor unit and the wheel bearing unit. And a speed reducer part that decelerates the rotation of the part and transmits it to the wheel bearing part. A motor part and a reduction gear part are accommodated in the casing. The casing is attached to the vehicle body via a suspension device (suspension).

  In the in-wheel motor drive device having the above-described configuration, a small motor with a low torque and a high rotation is adopted for the motor unit from the viewpoint of making the device compact. 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 rotatably held 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, 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 to rotate the curved plate. The main part is composed of a plurality of inner pins that are transmitted to the reduction gear output shaft.

  In this in-wheel motor drive device, a lubrication mechanism for supplying lubricating oil to the motor unit and the reduction gear unit is provided. The lubrication mechanism is provided in the motor unit and is provided with a rotary pump that pumps the lubricating oil, an oil tank that is provided in a lower part of the casing and stores the lubricating oil, an oil passage provided in the motor unit, the speed reducer unit, and the casing, and It has an oil drainage hole, and has a structure in which lubricating oil circulates inside the motor unit and the reduction gear unit.

  In this lubrication mechanism, when the rotary pump rotates, the lubricating oil stored in the oil tank is sucked into the rotary pump and supplied into the motor unit and the speed reducer unit. Lubricating oil pumped from the rotary pump is supplied to the motor part via an oil path provided in the casing, and is supplied to the speed reducer part via an oil path provided on the speed reducer input shaft.

  Lubricating oil supplied to the reduction gear portion flows into the motor portion from an oil drain hole provided in a lower portion of a casing that partitions the motor portion and the reduction gear portion. The lubricating oil supplied to the motor unit is discharged into the oil tank from the oil drain hole provided in the bottom of the casing of the motor unit together with the lubricating oil entering the motor unit from the reduction gear unit.

JP2011-189919A

  By the way, the above-described conventional in-wheel motor drive device must be housed in the wheel of the vehicle, and it is necessary to suppress the unsprung weight, and further downsizing is essential in order to secure a large cabin space. It becomes a requirement. Due to the downsizing of such an in-wheel motor drive device itself, it is difficult to secure a sufficient volume for the oil tank disposed below the casing. As a result, the lubricating oil is stored inside the motor unit and the speed reducer unit.

  Here, in order to secure the required amount of lubricating oil in the motor unit and the speed reducer unit, if the amount of lubricating oil filled is increased, the oil level of the lubricating oil stored inside the speed reducer unit becomes higher, and the speed of the speed reducer unit A part of the curved plate is immersed in the lubricating oil. Since the lubricating oil is a viscous fluid, the lubricating oil that comes into contact with a portion of the curved plate is dragged and scraped up in the rotational direction of the curved plate. As the rotational speed of the curved plate increases, the amount of lubricating oil in contact with the curved plate increases and the load acting between the curved plate and the lubricating oil also increases due to the viscosity of the lubricating oil. To increase.

  Further, when the lubricating oil thus scraped comes into contact with a plurality of rotating inner pins, the lubricating oil is dragged in the direction of rotation of the inner pins and further stirred up, and the stirring resistance is further increased. As a result, the lubricating oil stored in the reduction gear unit is scraped up in the rotational direction of the curved plate and the inner pin, and the oil level is greatly inclined and bubbles. As described above, when the oil level of the lubricating oil is greatly inclined and the lubricating oil is bubbled, the lubricating oil stored in the reduction gear part remains in the reduction gear part, and the motor part from the drain hole located at the lower part of the casing. It becomes difficult to flow into.

  In addition, when the vehicle turns, the in-wheel motor drive device housed inside the wheel located outside the turn causes the lubricating oil stored inside the speed reducer part to be drawn to the outside of the turn by the centrifugal force due to the turn. Become. As a result, a larger amount of the lubricating oil comes into contact with a part of the curved plate and the inner pin, and the scraping of the lubricating oil and the increase in the stirring resistance become remarkable. Thus, when the inclination of the oil surface of the lubricating oil and the foaming of the lubricating oil become prominent, the lubricating oil stored in the reduction gear portion becomes more difficult to flow from the oil drain hole into the motor portion.

  As described above, when the lubricating oil stored in the reduction gear part becomes difficult to flow into the motor part, the amount of lubricating oil in the oil tank decreases with the rotation of the rotary pump. As a result, the amount of lubricating oil discharged from the rotary pump is reduced, and it may be difficult for the rotary pump to discharge the amount of lubricating oil required by the motor unit and the speed reducer unit.

  Therefore, the present invention has been proposed in view of the above-mentioned problems, and the object of the present invention is to improve the oil draining performance from the reduction gear unit, thereby improving the quality and durability of the in-wheel motor. It is to provide a driving device.

  As technical means for achieving the above-mentioned object, the present invention comprises a motor part, a reduction gear part, a wheel bearing part, and a casing for housing the motor part and the reduction gear part, and the motor of the motor part. An in-wheel motor drive device that decelerates rotation at the speed reducer part and rotates the speed reducer output shaft, and is stored at the bottom of the partition part of the casing that partitions the speed reducer part and the motor part at the bottom of the speed reducer part An overflow hole is provided for draining the lubricating oil to the motor part, and overflowing the partitioning part on the side where the lubricating oil is scraped up by the rotation of the speed reducer part, to the motor part. The hole is provided along the rotation direction of the reduction gear unit.

  In the present invention, the lubricating oil stored at the bottom of the speed reducer portion is caused to flow out from the oil drain hole to the motor portion, and the lubricating oil scraped up by the rotation of the speed reducer portion is allowed to flow out from the overflow hole to the motor portion. Therefore, the lubricating oil from the speed reducer part can easily flow into the motor part without being affected by the scraping and foaming of the lubricating oil due to the rotation of the speed reducer part, and the oil drained from the speed reducer part in the in-wheel motor drive device The performance can be improved.

  The overflow hole in the present invention is preferably formed in a region below the rotation center of the reduction gear output shaft. Even if the oil level of the lubricating oil scraped up by rotation of the speed reducer section is greatly inclined and foams, the oil level of the lubricating oil and foaming occur in the region below the rotation center of the speed reducer output shaft. If the overflow hole is formed in the region below the rotation center of the reduction gear output shaft, the minimum necessary overflow hole is sufficient.

  The overflow hole in the present invention is configured such that the oil surface of the lubricating oil is below the lowest point of the outermost diameter rotation trajectory of the plurality of inner pins provided at a plurality of locations in the circumferential direction of the reduction gear output shaft. It is desirable. If it does in this way, it can control that lubricating oil contacts a plurality of rotating inner pins. As a result, since the inclination and foaming of the oil surface of the lubricating oil can be suppressed, the lubricating oil stored inside the reduction gear section can easily flow into the motor section from the oil drain hole.

  According to the present invention, the lubricating oil stored at the bottom of the speed reducer part is allowed to flow out from the oil drain hole to the motor part, and the lubricating oil scraped up by the rotation of the speed reducer part is allowed to flow out from the overflow hole to the motor part. Therefore, the lubricating oil from the speed reducer part can easily flow into the motor part without being affected by the scraping and foaming of the lubricating oil due to the rotation of the speed reducer part, and from the speed reducer part in the in-wheel motor drive device. Oil draining performance can be improved. As a result, an in-wheel motor drive device with high quality and excellent durability can be realized.

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 figure which shows an example of an overflow hole in the section which meets the QQ line of FIG. It is a cross section which follows the QQ line of Drawing 1, and is a figure showing other examples of an overflow hole. FIG. 2 is a longitudinal sectional view of an in-wheel motor drive device showing an oil level of lubricating oil when the vehicle is traveling straight in the speed reducer portion of FIG. 1. FIG. 2 is a longitudinal sectional view of an in-wheel motor drive device showing an oil level of lubricating oil when the vehicle turns in the speed reducer portion of FIG. 1. It is a top view which shows schematic structure of the electric vehicle carrying an in-wheel motor drive device. It is back sectional drawing which shows the electric vehicle of FIG.

  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. 10 is a schematic plan view of the electric vehicle 11 on which the in-wheel motor drive device 21 is mounted, and FIG. 11 is a schematic cross-sectional view of the electric vehicle 11 as viewed from the rear. As shown in FIG. 10, 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. 11, 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. Therefore, 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, and further, 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. A wheel bearing portion C that transmits to a rear wheel 14 (see FIGS. 10 and 11) as a drive wheel is provided. The motor portion A and the speed reducer portion B are housed in a casing 22, and the wheel housing 12 a of the electric vehicle 11 is provided. (See FIG. 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 (including serration fitting; hereinafter the same), 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 28b is connected to a hub wheel 32 as an inner member of the wheel bearing portion C so that torque can be transmitted by spline fitting, and the output of the reduction gear portion B is transmitted to the rear wheel 14 (see FIGS. 10 and 11). To communicate. 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 supported by the rolling bearing 41 so as to be rotatable with respect to the eccentric portions 25a and 25b.

  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. The outer pin housing 60 is prevented from rotating around the casing 22, and is supported in a floating state.

The counterweight 29 is substantially fan-shaped and has a through hole that engages with the speed reducer input shaft 25. In order to counteract the unbalanced inertia couple generated by the rotation of the curved plates 26a and 26b, the counterweights 29a and 25b The eccentric portions 25a and 25b are arranged 180 ° out of phase with each other at adjacent positions. Assuming that the center point in the rotational axis direction between the two curved plates 26a and 26b is G (see FIG. 3), the distance between the central point G and the center of the curved plate 26a is L _{1 on} the right side of the central point G. , The sum of the mass of the curved plate 26a, the rolling bearing 41 and the eccentric portion 25a is m ₁ , the amount of eccentricity of the center of gravity of the curved plate 26a from the rotational axis is ε ₁ , and the distance between the center point G and the counterweight 29 is L _{2. The} relationship satisfying L ₁ × m ₁ × ε ₁ = L ₂ × m ₂ × ε ₂ , where m _{2 is} the mass of the counterweight 29 and ε ₂ is the amount of eccentricity of the center of gravity of the counterweight 29 from the rotational axis. It has become. 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 larger than the outer diameter dimension of the inner pin 31 (the maximum outer diameter including the needle roller bearing 31a) by a predetermined dimension. Is set.

  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 a part of the inner pins 31 from the curved plates 26a and 26b is supported by all the inner pins 31 via the flange portion 28a and the stabilizer 31b, the stress acting on the inner pins 31 is reduced and 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 includes a hub wheel 32 connected to the reducer output shaft 28 so as to be able to transmit torque, and an inner ring 33 a fitted to the outer peripheral surface of the hub wheel 32. An outer ring 33b fitted and fixed to the casing 22, a plurality of balls 33c disposed between the hub wheel 32, the inner ring 33a and the outer ring 33b, and a cage 33d for holding the plurality of balls 33c. Double-row angular contact ball bearing. Seal members 33e are provided at both axial ends of the wheel bearing 33. The rear wheel 14 (see FIGS. 10 and 11) is connected to the hub wheel 32 of the wheel bearing 33 by a bolt 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 suction port 55 and the discharge port 56 of the rotary pump 51 described above are provided in the motor housing of the casing 22. An oil tank 22 d is integrally provided in the motor housing of the casing 22.

  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.

  An oil drain hole 22b communicating with the inside of the motor part A and the inside of the speed reducer part B is provided at the lower part of the partition wall part 22c between the motor part A and the speed reducer part B of the casing 22, and the motor part A An oil drain hole 22f for discharging the lubricating oil inside the motor part A to the oil tank 22d is provided at the bottom of the casing 22 at the position.

  The oil tank 22d is rearward in the vehicle traveling direction at a position below the casing 22 (FIG. 6) in order to cope with the suspension configuration of the vehicle, the deviation of the lubricating oil due to inertia during acceleration and deceleration of the vehicle, and the oil level change during climbing. And on the left side of FIG. 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 to the inside of the rolling 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 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 reduction gear part B moves from the oil drain hole 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 discharge hole 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.

  In this in-wheel motor drive device 21, as shown in FIGS. 6 and 7, in addition to the existing oil drain hole 22 b through which the lubricating oil stored at the bottom of the speed reducer part B flows out to the motor part A, the speed reducer part It was conceived that an overflow hole 22g for allowing the lubricating oil scraped up by B to flow out to the motor part A is provided in the partition part 22c of the casing 22. The oil drain holes 22 b are provided at two lowermost portions of the partition wall portion 22 c of the casing 22. The overflow hole 22g is provided in the partition wall portion 22c on the side where the lubricating oil is scraped up by the rotation of the speed reducer portion B along the rotation direction of the speed reducer portion B (see the white arrow in the figure).

  FIG. 6 illustrates a structure in which one overflow hole 22g is provided adjacent to the oil drain hole 22b, and FIG. 7 illustrates a structure in which two overflow holes 22g adjacent to the oil drain hole 22b are provided. Here, a plurality of mounting holes 22h for fixing the reduction gear housing of the casing 22 to the motor housing with bolts are formed in the partition wall portion 22c. Therefore, since the oil drain hole 22b is disposed between the two adjacent mounting holes 22h, the opening area cannot be increased. The overflow hole 22g is also disposed between the two adjacent mounting holes 22h.

  The in-wheel motor drive device 21 must be housed inside the wheel of the vehicle, and it is necessary to suppress the unsprung weight. Further, in order to secure a large cabin space, downsizing is an essential requirement. Due to the downsizing of such an in-wheel motor drive device itself, it is difficult to secure a sufficient volume for the oil tank 22d disposed below the casing 22, so that the motor part A and the reduction gear part B Lubricating oil will accumulate inside.

  Here, in order to secure the necessary amount of lubricating oil in the motor part A and the speed reducer part B, if the amount of the lubricating oil filled is increased, the oil level of the lubricating oil stored inside the speed reducer part B is increased and curved. Part of the plates 26a, 26b is immersed in the lubricating oil. Since this lubricating oil is a viscous fluid, the lubricating oil that contacts a part of the curved plates 26a and 26b is dragged and scraped up in the rotational direction of the curved plates 26a and 26b. As the rotational speed of the curved plates 26a, 26b increases, the amount of lubricating oil that contacts the curved plates 26a, 26b increases, and the load acting between the curved plates 26a, 26b and the lubricating oil also increases due to the viscosity of the lubricating oil. Therefore, the agitation resistance of the lubricating oil increases.

  When the lubricating oil thus scooped up contacts the plurality of rotating inner pins 31, the lubricating oil is dragged in the rotational direction of the inner pins 31 and further stirred up, and the stirring resistance is further increased. . As a result, the lubricating oil stored in the reducer B is scraped up in the rotational direction of the curved plates 26a and 26b and the inner pin 31, and the oil level S (see the one-dot chain line in FIGS. 6 and 7) is horizontal. Will also be greatly inclined and foam. As described above, when the oil level S of the lubricating oil is greatly inclined and the lubricating oil is bubbled, the lubricating oil stored in the reduction gear portion B remains in the reduction gear portion B, and is located below the partition wall portion 22c of the casing 22. It becomes difficult to flow into the motor part A from the provided oil drain hole 22b.

  As shown in FIG. 8, when the vehicle goes straight, the lubricating oil stored in the reduction gear B is in a substantially horizontal state in the vehicle width direction (see the cross-hatched portion in the figure). However, when the vehicle turns, for example, when turning leftward in the direction of travel as shown in FIG. 10 (see the white arrow in the figure), the vehicle is stored inside the right wheel located outside the turn. In the wheel motor drive device 21, as shown in FIG. 9, the lubricating oil stored in the reduction gear section B is attracted to the outside of the turn (the vehicle width direction outside) by the centrifugal force due to the turn (in the figure, the figure). (See the cross-hatched part). As a result, a larger amount of the lubricating oil comes into contact with a part of the curved plates 26a and 26b and the inner pin 31, and the scraping of the lubricating oil and the increase in the stirring resistance become remarkable. Thus, when the inclination of the oil surface of the lubricating oil and the foaming of the lubricating oil become prominent, the lubricating oil inside the speed reducer part B becomes more difficult to flow into the motor part A from the oil drain hole 22b. In FIG. 8 and FIG. 9, hatching of members constituting the in-wheel motor drive device 21 is omitted.

  In the in-wheel motor drive device 21 of this embodiment, since the lubricating oil scraped up by the rotation of the curved plates 26a and 26b and the inner pin 31 is caused to flow out from the overflow hole 22g to the motor part A, the curved plate 26a. , 26b and the inner pin 31 are not affected by the scraping and bubbling of the lubricating oil, so that the lubricating oil from the speed reducer part B can easily flow into the motor part A, and the speed reducer part in the in-wheel motor drive device 21 The oil drainage performance from B can be improved. As a result, a decrease in the amount of lubricating oil in the oil tank 22d accompanying the rotation of the rotary pump 51 can be suppressed. Thus, since the amount of lubricating oil in the oil tank 22d can be secured, the rotary pump 51 can easily discharge the amount of lubricating oil required by the motor part A and the speed reducer part B.

  The above-described overflow hole 22g is formed in a region below the rotation center of the reduction gear output shaft 28 (region below the MM line in the drawing) as shown in FIGS. Even if the oil level S of the lubricating oil scraped up by the rotation of the curved plates 26a and 26b and the inner pin 31 is inclined more than horizontal and bubbles, the inclination and foaming of the oil level S of the lubricating oil are reduced. Since the overflow hole 22g is formed in the area below the rotation center of the reduction gear output shaft 28, the minimum necessary number (1 or 2) of overflow holes is generated. Just 22g.

Further, as shown in FIGS. 6 and 7, the overflow hole 22 g has a plurality of inner pins 31 in which the oil level S of the lubricated oil is provided at a plurality of locations in the circumferential direction of the reducer output shaft 28. It is configured to be below the lowest point of the outermost diameter rotation orbit (below the NN line in the figure). That is, by causing the scraped-up lubricating oil to flow out from the overflow hole 22g to the motor part A, the lubricating oil becomes the oil surface S ₀ (below in the drawing) that is below the lowest point of the outermost diameter rotation track of the inner pin 31. It becomes easy to shift to (see broken line). Thereby, it can suppress that lubricating oil contacts the some inner pin 31 to rotate. As a result, the lubricating oil stored inside the speed reducer part B can easily flow into the motor part A from the oil drain hole 22b.

  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. In the in-wheel motor drive device 21 of this embodiment, the example which employ | adopted the cycloid type speed reducer was shown, However, It is not restricted to this, It is a planetary speed reducer, a 2-axis parallel speed reducer, and other speed reducers. Also good.

  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. Furthermore, although the electric vehicle 11 shown in FIG. 10 and FIG. 11 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 22 Casing 22b Oil drain hole 22c Partition part 22g Overflow hole 28 Reduction gear output shaft A Motor part B Reduction gear part C Wheel bearing part

Claims (3)

A motor unit, a reducer unit, a wheel bearing unit, and a casing that accommodates the motor unit and the reducer unit, and the motor rotation of the motor unit is decelerated by the reducer unit to reduce the output shaft of the reducer An in-wheel motor drive device for rotation,
An oil drain hole is provided in the lower part of the partition wall of the casing for partitioning the speed reducer part and the motor part, and the lubricating oil stored in the bottom part of the speed reducer part flows into the motor part, and lubrication is performed by the rotation of the speed reducer part. An in-wheel motor drive characterized in that an overflow hole is provided along the rotation direction of the speed reducer part in the partition part on the side where the oil is raked up, to allow the lubricating oil scooped up by the speed reducer part to flow out to the motor part apparatus.   The in-wheel motor drive device according to claim 1, wherein the overflow hole is formed in a region below a rotation center of the reduction gear output shaft.   The overflow hole is configured such that an oil level of the lubricating oil is equal to or lower than a lowest point of an outermost diameter rotation track of a plurality of inner pins provided at a plurality of positions in a circumferential direction of the reduction gear output shaft. The in-wheel motor drive device according to claim 1.

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