JP2008309264A - Cycloid reduction gear and in-wheel motor drive device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly reliable in-wheel motor drive device having excellent durability by employing a bearing that can stably support an eccentric portion even under a high speed rotation environment. <P>SOLUTION: A cycloid reduction gear B includes a casing 22, a motor-side rotating member 25, curved plates 26a, 26b, external pins 27, internal pins 31 provided on a wheel-side rotating member 28, holes 30a defined by the curved plates 26a, 26b and each having a diameter larger by a predetermined amount than the outer diameter of the internal pin 31 so as to receive the internal pin 31 therein, and cylindrical members 31a fitted on the internal pins 31 at positions where the cylindrical members 31a make contact with the inner wall surfaces of the holes 30a. The internal pins 31 and the cylindrical members 31a are fitted to each other with predetermined radial gaps disposed therebetween. Dynamic pressure grooves 31b are formed in either of the outer diameter surfaces of the internal pins 31 and the inner diameter surfaces of the cylindrical members 31a, thereby constituting a dynamic pressure bearing. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a cycloid reducer and an in-wheel motor drive device employing a cycloid reducer.

  A conventional in-wheel motor drive device 101 is described in, for example, Japanese Patent Application Laid-Open No. 2006-258289 (Patent Document 1). Referring to FIG. 9, an in-wheel motor drive device 101 includes a motor unit 103 that generates a driving force inside a casing 102 that is attached to a vehicle body, a wheel hub bearing unit 104 that is connected to a wheel, and a motor unit 103. And a speed reduction portion 105 that reduces the rotation and transmits the reduced speed to the wheel hub bearing portion 104.

  In the in-wheel motor drive device 101 having the above configuration, a low torque and high rotation motor is employed for the motor unit 103 from the viewpoint of making the device compact. On the other hand, the wheel hub bearing portion 104 requires a large torque to drive the wheel. Therefore, a cycloid reducer that is compact and can provide a high reduction ratio may be employed as the reduction unit 105.

Moreover, the speed reduction part 105 to which the conventional cycloid reduction gear is applied includes a motor-side rotating member 106 having eccentric parts 106a and 106b, curved plates 107a and 107b disposed on the eccentric parts 106a and 106b, and curved plates 107a and 107b. A rolling bearing 111 that rotatably supports the motor-side rotating member 106, a plurality of outer pins 108 that engage with the outer peripheral surfaces of the curved plates 107a and 107b to cause the curved plates 107a and 107b to rotate. And a plurality of inner pins 109 that transmit the rotation of the curved plates 107a and 107b to the wheel-side rotating member 110.
JP 2006-258289 A

  In the in-wheel motor drive device 101 configured as described above, in order to reduce the contact resistance between the curved plates 107a and 107b and the outer pin 108 and between the curved plates 107a and 107b and the inner pin 109, the outer pin 108 and Roller bearings 108a and 109a are attached at positions where the inner pins 109 come into contact with the curved plates 107a and 107b.

  Here, the number of outer pins 108 and inner pins 109 is determined by the reduction ratio of the cycloid reducer. That is, the more rolling bearings 108a and 109a are required as the cycloid reducer with a higher reduction ratio is employed. This causes an increase in the product cost of the in-wheel motor drive device 101.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a cycloid reduction gear with low torque loss and a low torque loss, and an in-wheel motor drive device employing such a cycloid reduction gear.

  The cycloid reducer according to the present invention has a casing, an input shaft having an eccentric portion, and a through-hole through which the eccentric portion is inserted, and performs a revolving motion around the rotational axis as the input shaft rotates. Revolving member, formed on outer ring engaging member that is held by casing and engages with outer peripheral portion of revolving member to cause revolving motion of revolving member, inner pin provided on output shaft, revolving member, inner pin A hole that is larger in diameter than the outer diameter of the inner pin to receive the inner pin, and a cylindrical member that fits the inner pin at a position that contacts the inner wall surface of the hole. And a motion conversion mechanism that converts the motion into a rotational motion centered on the shaft and transmits it to the output shaft. The inner pin and the cylindrical member are fitted with a predetermined radial gap, and a dynamic pressure groove is formed on one of the outer diameter surface of the inner pin and the inner diameter surface of the cylindrical member. Constitute.

  Since the inner pin and the cylindrical member are not in contact with each other when the dynamic pressure bearing rotates, the frictional resistance can be reduced. In addition, the hydrodynamic bearing is less expensive than the rolling bearing. As a result, a cycloid reduction gear with low torque loss and low torque can be obtained.

  As one embodiment, the outer peripheral engagement member has an outer pin fixed to the casing, and a cylindrical member fitted to the outer pin at a position in contact with the outer peripheral portion of the revolution member. The outer pin and the cylindrical member are fitted with a predetermined radial gap, and a dynamic pressure groove is formed on one of the outer diameter surface of the outer pin and the inner diameter surface of the cylindrical member. Constitute.

  As another embodiment, the outer peripheral engagement member has an outer pin that engages with the outer peripheral portion of the revolution member, and a cylindrical member that is fixed to the casing and receives the outer pin on the inner diameter surface. The outer pin and the cylindrical member are fitted with a predetermined radial gap, and a dynamic pressure groove is formed on one of the outer diameter surface of the outer pin and the inner diameter surface of the cylindrical member. Constitute.

  By providing a dynamic pressure bearing on the outer pin by any one of the methods described above, a cycloid reduction gear with a lower cost and less torque loss can be obtained.

  Preferably, the dynamic pressure groove is formed by rolling. More preferably, the cylindrical member is a sintered alloy formed by powder metallurgy. By adopting these manufacturing methods, manufacturing costs can be further reduced.

  The in-wheel motor drive device according to the present invention includes a motor unit that rotationally drives a motor-side rotating member as an input shaft, and the motor-side rotating member that decelerates the rotation and transmits the rotation to the wheel-side rotating member as an output shaft. One of the cycloid reduction gears and a wheel hub fixedly connected to the wheel-side rotating member are provided. By adopting the cycloid reducer having the above configuration, a highly reliable in-wheel motor drive device can be obtained.

  According to the present invention, a cycloid reduction gear with low torque loss and low torque loss can be obtained by forming a hydrodynamic bearing on at least one of the inner pin and the outer pin. In addition, by adopting such a cycloid reducer, a highly reliable in-wheel motor drive device can be obtained.

  With reference to FIG. 7 and FIG. 8, the electric vehicle 11 which employ | adopted the in-wheel motor drive device 21 which concerns on one Embodiment of this invention is demonstrated. 7 is a schematic view of the electric vehicle 11, and FIG. 8 is a schematic view of the electric vehicle 11 as viewed from the rear.

  Referring to FIG. 7, an electric vehicle 11 includes an in-wheel motor drive device that transmits driving force to a chassis 12, front wheels 13 as steering wheels, rear wheels 14 as drive wheels, and left and right rear wheels 14. 21. Referring to FIG. 8, the rear wheel 14 is accommodated in a 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 to the 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 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 driving wheels to the road surface. Is desirable.

  The electric vehicle 11 needs to be provided with a motor, a drive shaft, a differential gear mechanism, and the like on the chassis 12 by providing an in-wheel motor drive device 21 for driving the left and right rear wheels 14 inside the wheel housing 12a. This eliminates the need to secure a wide cabin space and control the rotation of the left and right drive wheels.

  On the other hand, in order to improve the running stability of the electric vehicle 11, it is necessary to suppress the unsprung weight. In addition, in-wheel motor drive device 21 is required to be downsized in order to secure a wider cabin space. Therefore, an in-wheel motor drive device 21 according to an embodiment of the present invention as shown in FIG. 1 is employed.

  With reference to FIGS. 1-3, the in-wheel motor drive device which concerns on one Embodiment of this invention is demonstrated. 1 is a schematic cross-sectional view of the in-wheel motor drive device, FIG. 2 is a cross-sectional view taken along the line II-II of FIG. 1, and FIG. 3 is an enlarged view around the eccentric portions 25a and 25b.

  First, referring to FIG. 1, an in-wheel motor drive device 21 includes a motor unit A that generates a driving force, a deceleration unit B that decelerates and outputs the rotation of the motor unit A, and an output from the deceleration unit B. A wheel hub bearing portion C for transmitting to the drive wheel 14 is provided, and the motor portion A and the speed reduction portion B are accommodated in the casing 22 and attached to the wheel housing 12a of the electric vehicle 11 as shown in FIGS. .

  The motor part A includes a stator 23 fixed to the casing 22, a rotor 24 disposed at a position facing the inner side of the stator 23 with a radial gap, and a rotor 24 fixedly connected to the inner side of the rotor 24. It is a radial gap motor provided with the motor side rotation member 25 which rotates integrally. Further, a sealing member 39 is provided on the end surface of the motor part A opposite to the speed reducing part B in order to prevent dust from entering the motor part A.

  The rotor 24 has a flange-shaped rotor portion 24 a and a cylindrical hollow portion 24 b, and is rotatably supported by the casing 22 by a rolling bearing 34. In addition, a sealing member 35 is provided between the casing 22 and the rotor 24 in order to prevent the lubricant encapsulated in the speed reduction part B from entering the motor part A.

  The motor-side rotation member 25 is disposed from the motor part A to the speed reduction part B in order to transmit the driving force of the motor part A to the speed reduction part B, and has eccentric parts 25a and 25b in the speed reduction part B. One end of the motor-side rotating member 25 is fitted to the rotor 24 and is supported by rolling bearings 36a and 36b at both ends of the speed reduction unit B. Further, the two eccentric portions 25a and 25b are provided with a 180 ° phase change in order to cancel the centrifugal force due to the eccentric motion.

  The deceleration part B is held at a fixed position on the casing 22 and curved plates 26a and 26b as revolving members that are rotatably held by the eccentric parts 25a and 25b, and engages with the outer peripheral parts of the curved plates 26a and 26b. A plurality of outer pins 27 as outer peripheral engagement members, a motion conversion mechanism that transmits the rotation of the curved plates 26 a and 26 b to the wheel-side rotation member 28, and a counterweight 29 are provided. In addition, the speed reduction part B is provided with a speed reduction part lubrication mechanism that supplies lubricating oil to the speed reduction part B.

  The wheel side rotation member 28 includes a flange portion 28a and a shaft portion 28b. Holes for fixing the inner pins 31 are formed on the end face of the flange portion 28a at equal intervals on the circumference around the rotation axis of the wheel side rotation member 28.

  Referring to FIG. 2, the curved plate 26 a has a plurality of corrugations composed of trochoidal curves such as epitrochoids on the outer peripheral portion, and a plurality of through holes 30 a and 30 b penetrating from one end face to the other end face. Have A plurality of through holes 30a are provided at equal intervals on the circumference centered on the rotation axis of the curved plate 26a, and receive inner pins 31 described later. Further, the through hole 30b is provided at the center of the curved plate 26a and is fitted to the eccentric portion 25a.

  The curved plate 26a is rotatably supported by the rolling bearing 41 with respect to the eccentric portion 25a. Referring to FIG. 3, this rolling bearing 41 is fitted to the outer diameter surface of the eccentric portion 25a, and the inner ring member 42 having an inner raceway surface 42a on the outer diameter surface, and the inner diameter of the through hole 30b of the curved plate 26a. The outer raceway surface 43 formed directly on the surface, a plurality of cylindrical rollers 44 disposed between the inner raceway surface 42a and the outer raceway surface 43, and a cage for maintaining the spacing between the adjacent cylindrical rollers 44 (not shown) It is a cylindrical roller bearing provided with.

  The outer pins 27 are provided at equal intervals on a circumferential track centering on the rotation axis of the motor side rotation member 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 has a cylindrical member 27a at a position where it abuts against the curved plates 26a and 26b, and the outer pin 27 and the cylindrical member 27a constitute a hydrodynamic bearing.

  The counterweight 29 has a disc shape and has a through-hole that fits with the motor-side rotation member 25 at a position off the center, in order to counteract the unbalanced inertia couple generated by the rotation of the curved plates 26a and 26b. It is arranged at a position adjacent to each eccentric part 25a, 25b with a 180 ° phase change from the eccentric part.

Here, referring to FIG. 3, if the center point between the two curved plates 26a, 26b is G, the distance between the central point G and the center of the curved plate 26a is the right side of the central point G in FIG. L ₁ , the sum of the masses of the curved plate 26 a, the rolling bearing 41 and the eccentric portion 25 a is m ₁ , and the eccentric amount of the center of gravity of the curved plate 26 a from the rotational axis is ε ₁ , and the distance between the center point G and the counterweight 29 Is L ₂ , the mass of the counterweight 29 is m ₂ , and the eccentric amount of the center of gravity of the counterweight 29 from the rotational axis is ε ₂ , L ₁ × m ₁ × ε ₁ = L ₂ × m ₂ × ε ₂ It is a satisfying relationship. A similar relationship is also established between the curved plate 26b on the left side of the center point G in FIG.

  The motion conversion mechanism includes a plurality of inner pins 31 held by the wheel-side rotating member 28 and through holes 30a provided in the curved plates 26a and 26b. The inner pins 31 are provided at equal intervals on a circumferential track centering on the rotation axis of the wheel side rotation member 28, and are fixed to the wheel side rotation member 28. Further, the inner pin 31 has a cylindrical member 31a at a position where it comes into contact with the curved plates 26a and 26b, and the inner pin 31 and the cylindrical member 31a constitute a hydrodynamic bearing.

  On the other hand, 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 indicates the outer diameter dimension of the inner pin 31 ("maximum outer diameter including the cylindrical member 31a"). The same shall apply hereinafter).

  The speed reduction unit lubrication mechanism supplies lubricating oil to the speed reduction unit B, and includes a lubricating oil passage 25c, a lubricating oil supply port 25d, a lubricating oil discharge port 22b, and a circulation oil passage 22c.

  The lubricating oil passage 25c extends in the axial direction inside the motor-side rotating member 25. The lubricating oil passage 25c is provided with an enlarged diameter portion 25e whose cross-sectional area increases in the direction in which the lubricating oil flows (from the right to the left in FIG. 1). The lubricating oil passage 25c is a through-hole that penetrates the motor-side rotating member 25 in the axial direction, and the steel ball 25f is press-fitted further downstream (left end in FIG. 1) from the connection portion with the lubricating oil supply port 25d. This prevents the leakage of lubricating oil.

  The lubricating oil supply port 25d extends from the lubricating oil passage 25c toward the outer diameter surface of the motor-side rotating member 25. In this embodiment, the lubricating oil supply port 25d is provided in the eccentric portions 25a and 25b.

  The enlarged diameter portion 25e is disposed on the upstream side of the connecting portion with the lubricating oil supply port 25d, more specifically, at the inlet of the lubricating oil passage 25c. Moreover, the wall surface of the enlarged diameter part 25e in this embodiment is a taper shape which spreads from the upstream (side near the circulating oil path 22c) of the motor side rotation member 25 toward the downstream, and the taper angle is not particularly limited.

  In addition, referring to FIG. 2, at least one portion of casing 22 at the position of speed reduction portion B is provided with a lubricating oil discharge port 22 b for discharging the lubricating oil inside speed reduction portion B. Further, the lubricating oil discharged from the lubricating oil discharge port 22b returns to the lubricating oil passage 25c via a circulating oil passage 22c that connects the lubricating oil discharge port 22b and the lubricating oil passage 25c.

  The flow of the lubricating oil in the deceleration portion B having the above configuration will be described. First, the lubricating oil is sent in the downstream direction (left side in FIG. 1) of the lubricating oil passage 25c by centrifugal force along the enlarged diameter portion 25e provided at the inlet of the lubricating oil passage 25c. Further, the lubricating oil flowing through the lubricating oil passage 25 c flows out from the opening 42 b penetrating the lubricating oil supply port 25 d and the inner ring member 42 due to the centrifugal force accompanying the rotation of the motor-side rotating member 25.

  Since centrifugal force further acts on the lubricating oil inside the speed reduction portion B, the inner raceway surface 42a, the outer raceway surface 43, the contact portion between the curved plates 26a, 26b and the inner pin 31, and the curved plates 26a, 26b and the outer It moves to the outside in the radial direction while lubricating the contact portion with the pin 27 and the like.

  Then, the lubricating oil that has reached the inner wall surface of the casing 22 is discharged from the lubricating oil discharge port 22b to the outside of the speed reduction unit B, and returns to the lubricating oil path 25c via the circulating oil path 22c. Here, a flow in the same direction as the rotation direction of the curved plates 26a and 26b is formed in the lubricating oil inside the speed reduction portion B. Since the lubricating oil passing through the circulating oil passage 22c reaches the lubricating oil passage 25c by the inertial force of this flow, an oil pump or the like for circulating the lubricating oil can be omitted.

  In this way, by supplying the lubricating oil from the motor side rotating member 25 to the speed reduction unit B, the shortage of the lubricating oil amount around the motor side rotating member 25 can be solved. Further, by discharging the lubricating oil from the lubricating oil discharge port 22b, it is possible to suppress the stirring resistance and reduce the torque loss of the deceleration unit B. Furthermore, by omitting an oil pump or the like for circulating the lubricating oil, it contributes to weight reduction of the in-wheel motor drive device 21.

  The hydrodynamic bearing formed on the inner pin 31 will be described in detail with reference to FIG. First, the cylindrical member 31a is fitted to the inner pin 31 at a position where it abuts against the inner wall surface of the through hole 30b of the curved plates 26a, 26b. A predetermined radial gap is provided between the inner pin 31 and the cylindrical member 31a. The cylindrical member 31a rotates around the inner pin 31 as the curved plates 26a and 26b rotate.

  A herringbone-shaped dynamic pressure groove 31 b is formed on the outer diameter surface of the inner pin 31. In this embodiment, the dynamic pressure groove 31b is formed so that dynamic pressure is generated only when the cylindrical member 31a rotates in one direction (counterclockwise when viewed from the right side in FIG. 4).

  The cylindrical member 31a can be formed by, for example, powder metallurgy. In the powder metallurgy method, first, a metal powder is compressed in a mold to form a green compact having a predetermined shape. Next, it refers to a method of obtaining a sintered alloy by heating to a temperature below the melting point in a sintering furnace. The dynamic pressure groove 31b can be formed by, for example, rolling.

  Moreover, the thrust plate 31c for preventing the shift | offset | difference to the axial direction of the cylindrical member 31a is provided in the both ends of the cylindrical member 31a. At least one location of the thrust plate 31c is provided with a lubricating oil inlet 31d for supplying lubricating oil between the inner pin 31 and the cylindrical member 31a. Therefore, the lubricating oil is supplied from the outside to the radial gap between the inner pin 31 and the cylindrical member 31a.

  In the dynamic pressure bearing having the above configuration, when the curved plates 26a and 26b are stopped or rotating at an extremely low speed, sufficient dynamic pressure is not generated between the inner pin 31 and the cylindrical member 31a, and the cylindrical member 31a. Rotates while contacting the inner pin 31.

  On the other hand, when the curved plates 26a and 26b rotate at a certain speed or more, dynamic pressure is generated between the inner pin 31 and the cylindrical member 31a due to the interaction between the dynamic pressure groove 31b and the lubricating oil. As a result, the cylindrical member 31 a can rotate without contacting the inner pin 31.

  Thereby, the frictional resistance between the inner pin 31 and the cylindrical member 31a can be reduced. Moreover, the manufacturing cost can be reduced by forming the dynamic pressure groove 31b by rolling. As a result, it is possible to obtain the speed reduction portion B with low torque and low torque loss.

  In general, since the electric vehicle 11 is faster when moving forward than when moving backward, the dynamic pressure groove 31b in the above embodiment generates dynamic pressure when rotating in the direction of moving the electric vehicle 11 forward. It is desirable to form so as to.

  In the above-described embodiment, an example has been described in which the lubricant inlet 31d is provided in the thrust plate 31c and the lubricant is supplied between the inner pin 31 and the cylindrical member 31a. A lubricating oil passage extending along the axial center of the pin 31 and a lubricating oil supply port extending from the lubricating oil passage to the outer diameter surface of the inner pin 31 are formed, thereby lubricating between the inner pin 31 and the cylindrical member 31a. Oil may be supplied.

  In the above embodiment, the example in which the dynamic pressure groove 31b is formed on the outer diameter surface of the inner pin 31 is shown. However, the present invention is not limited to this, and the outer diameter surface of the inner pin 31 and the inner diameter surface of the cylindrical member 31a. A dynamic pressure groove may be provided in at least one of them. The dynamic pressure groove 31b is not limited to the herringbone shape, and any shape that can generate dynamic pressure between the inner pin 31 and the cylindrical member 31a can be employed.

  Further, although the hydrodynamic bearing is also formed on the outer pin 27, the description is omitted because it is common to the above contents. In the above embodiment, an example in which a dynamic pressure bearing is formed on both the outer pin 27 and the inner pin 31 has been shown. However, the present invention is not limited to this, and at least one of the outer pin 27 and the inner pin 31 is used. If a hydrodynamic bearing is provided on one side, the effect of the present invention can be obtained.

  As shown in FIG. 5, a dynamic pressure may be generated between the inner pin 41 and the cylindrical member 41a regardless of whether the cylindrical member 41a rotates in one direction or the other direction. Referring to FIG. 5, a first dynamic pressure groove that generates dynamic pressure on the outer diameter surface of inner pin 41 by rotation in one direction (counterclockwise when viewed from the right side of FIG. 5) of cylindrical member 41a. 41b and a second dynamic pressure groove 41c that generates dynamic pressure by rotation of the cylindrical member 41a in the other direction (clockwise when viewed from the right side in FIG. 5) are formed.

  The inner pin 41 shown in FIG. 5 has an advantageous effect when the in-wheel motor drive device 21 is used for an application in which both forward rotation and backward rotation rotate at a certain high speed. Furthermore, it is necessary to confirm the mounting direction of the inner pin 31 as shown in FIG. 4 when the in-wheel motor drive device 21 is assembled. On the other hand, since the inner pin 41 as shown in FIG. 5 does not need to be aware of the mounting direction, it is possible to effectively prevent troubles associated with errors during assembly.

  The wheel hub bearing portion C includes a wheel hub 32 fixedly connected to the wheel-side rotating member 28 and a wheel hub bearing 33 that holds the wheel hub 32 rotatably with respect to the casing 22. The wheel hub 32 has a cylindrical hollow portion 32a and a flange portion 32b. The drive wheel 14 is fixedly connected to the flange portion 32b by a bolt 32c. Further, the wheel-side rotating member 28 and the wheel hub 32 are coupled by a bolt 32d.

  The wheel hub bearing 33 is a double-row angular ball bearing that employs balls 33e as rolling elements. As the raceway surfaces of the balls 33e, a first outer raceway surface 33a (right side in the figure) and a second outer raceway surface 33b (left side in the figure) are provided on the inner diameter surface of the outer member 22a. A first inner raceway surface 33c facing the surface 33a is fitted to the outer diameter surface of the inner ring member 33h fitted and fixed to the wheel hub 32, and a second inner raceway surface 33d facing the second outer raceway surface 33b is made to the wheel hub 32. Each is provided on the outer diameter surface. A plurality of balls 33e are arranged between the first outer raceway surface 33a and the first inner raceway surface 33c and between the second outer raceway surface 33b and the second inner raceway surface 33d. The wheel hub bearing 33 includes a retainer 33f that holds the left and right rows of balls 33e, and a sealing member 33g that prevents leakage of a lubricant such as grease enclosed in the bearing and dust from the outside. Including.

  The operation principle of the in-wheel motor drive device 21 having the above configuration will be described in detail.

  The motor unit A receives, for example, an electromagnetic force generated by supplying an alternating current to the coil of the stator 23, and the rotor 24 composed of a permanent magnet or a magnetic material rotates. At this time, the rotor 24 rotates at a higher speed as a higher frequency voltage is applied to the coil.

  Thereby, when the motor side rotation member 25 connected to the rotor 24 rotates, the curved plates 26 a and 26 b revolve around the rotation axis of the motor side rotation member 25. At this time, the outer pin 27 engages with the curved waveform of the curved plates 26 a and 26 b to cause the curved plates 26 a and 26 b to rotate in the direction opposite to the rotation of the motor-side rotating member 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, but only the rotational motion of the curved plates 26 a and 26 b is transmitted to the wheel hub bearing portion C via the wheel-side rotating member 28.

  At this time, since the rotation of the motor-side rotating member 25 is decelerated by the speed reducing portion B and transmitted to the wheel-side rotating member 28, it is necessary for the drive wheel 14 even when the low torque, high rotation type motor portion A is adopted. It is possible to transmit an appropriate torque.

Note that the reduction ratio of the speed reduction unit B having the above-described configuration 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. The In the embodiment shown in FIG. 2, since Z _A = 12 and Z _B = 11, the reduction ratio is 1/11, and a very large reduction ratio can be obtained.

  In this way, by adopting the speed reduction unit B that can obtain a large speed reduction ratio without using a multi-stage configuration, the in-wheel motor drive device 21 having a compact and high speed reduction ratio can be obtained. Further, since the frictional resistance is reduced by providing the dynamic pressure bearings at positions where the outer pins 27 and the inner pins 31 are in contact with the curved plates 26a and 26b, the transmission efficiency of the speed reducing portion B is improved.

  By employing the in-wheel motor drive device 21 according to the above embodiment in the electric vehicle 11, the unsprung weight can be suppressed. As a result, the electric vehicle 11 having excellent running stability can be obtained.

  Next, another embodiment of the in-wheel motor drive device 21 will be described with reference to FIG. In addition, description of a common point with FIGS. 1-3 is abbreviate | omitted, and it demonstrates centering around difference.

  The outer pin 42 in the embodiment shown in FIG. 6 is a rod-shaped member including a large diameter portion 42a having a relatively large diameter at the center portion and a small diameter portion 42b having a relatively small diameter at both end portions. The large-diameter portion 42a is disposed at a position in contact with the curved plates 26a and 26b, and both are in direct contact. The small diameter portion 42 b is fitted into a cylindrical member 42 c fixed to the casing 22.

  More specifically, the cylindrical member 42 c is fitted and fixed to the casing 22. The small diameter portion 42b and the cylindrical member 42c are fitted with a predetermined radial gap. Further, a dynamic pressure groove 42d is provided on the outer diameter surface of the small diameter portion 52b. The dynamic pressure groove 42d in this embodiment may be resin molded.

  That is, the small diameter portion 42b and the cylindrical member 42c constitute a dynamic pressure bearing. The outer pin 42 configured as described above can rotate in a non-contact state with the cylindrical member 42c. As a result, the contact resistance due to the engagement of the outer pin 42 with the curved plates 26a and 26b can be reduced.

  The hydrodynamic bearing in this embodiment is the same as the hydrodynamic bearing described with reference to FIGS. 4 and 5 except that the cylindrical member 42c is fixed and the outer pin 42 rotates. Omitted.

  In the above embodiment, an example of the circulating oil passage 22c that passes through the outside of the in-wheel motor drive device 21 has been described. However, the present invention is not limited to this example. Good. In this case, since the circulating oil passage cannot be made very large from the viewpoint of the rigidity of the casing 22, it is desirable to provide a plurality of circulating oil passages in order to secure a necessary oil supply amount.

  Further, in the above-described embodiment, the example in which the lubricating oil supply port 25d is provided in the eccentric portions 25a and 25b has been described. However, from the viewpoint of stably supplying the lubricating oil to the rolling bearing 41, the lubricating oil supply port 25d is preferably provided in the eccentric portions 25a and 25b.

  Further, in the above embodiment, two curved plates 26a and 26b of the deceleration unit B are provided with 180 ° phase shifts. However, the number of the curved plates can be arbitrarily set. When three are provided, it is preferable to change the phase by 120 °.

  Moreover, although the motion conversion mechanism in said embodiment showed the example comprised by the inner pin 31 fixed to the wheel side rotation member 28, and the through-hole 30a provided in the curve boards 26a and 26b, Without being limited to the above, it is possible to adopt an arbitrary configuration capable of transmitting the rotation of the speed reduction unit B to the wheel hub 32. For example, it may be a motion conversion mechanism composed of an inner pin fixed to a curved plate and a hole formed in the wheel side rotation member.

  In addition, although description of the action | operation in said embodiment was performed paying attention to rotation of each member, the motive power containing a torque is actually transmitted from the motor part A to a driving wheel. Therefore, the power decelerated as described above is converted into high torque.

  Further, in the description of the operation in the above embodiment, power is supplied to the motor unit A to drive the motor unit A, and the power from the motor unit A is transmitted to the drive wheels 14, but on the contrary, When the vehicle decelerates or goes down a hill, the power from the drive wheel 14 side is converted into high-rotation and low-torque rotation by the deceleration unit B and transmitted to the motor unit A, and the motor unit A generates power. May be. 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.

  Further, a brake can be added to the configuration of the above embodiment. For example, in the configuration of FIG. 1, the casing 22 is extended in the axial direction to form a space on the right side of the rotor 24 in the drawing, the rotating member that rotates integrally with the rotor 24, and the casing 22 is non-rotatable and axial. A parking brake that locks the rotor 24 by disposing a movable piston and a cylinder that operates the piston and fitting the piston and the rotating member when the vehicle is stopped may be used.

  Alternatively, it may be a disc brake in which a flange formed on a part of a rotating member that rotates integrally with the rotor 24 and a friction plate installed on the casing 22 side are sandwiched by a cylinder installed on the casing 22 side. Furthermore, a drum brake can be used in which a drum is formed on a part of the rotating member, a brake shoe is fixed to the casing 22 side, and the rotating member is locked by friction engagement and self-engagement.

  In the above embodiment, an example of a cylindrical roller bearing is shown as a bearing for supporting the curved plates 26a and 26b. However, the present invention is not limited to this, and for example, a plain bearing, a cylindrical roller bearing, a tapered roller bearing, and a needle roller Regardless of whether it is a plain bearing or a rolling bearing, such as a bearing, a self-aligning roller bearing, a deep groove ball bearing, an angular contact ball bearing, or a four-point contact ball bearing, it does not matter whether the rolling element is a roller or a ball. Furthermore, any bearing can be applied regardless of whether it is a double row or a single row. Similarly, any type of bearing can be adopted for bearings arranged in other locations.

  However, the deep groove ball bearing has a higher allowable limit speed than the cylindrical roller bearing, but has a low load capacity. Therefore, in order to obtain a necessary load capacity, a large deep groove ball bearing must be employed. Therefore, from the viewpoint of making the in-wheel motor drive device 21 compact, a cylindrical roller bearing is suitable for the rolling bearing 41.

  In each of the above-described embodiments, an example in which a radial gap motor is adopted as the motor unit A has been described. However, the present invention is not limited to this, and a motor having an arbitrary configuration can be applied. 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 inner side of the stator with an axial gap.

  Furthermore, although the electric vehicle 11 shown in FIG. 7 has shown the example which used the rear wheel 14 as the driving wheel, it is not restricted to this, The front wheel 13 may be used as a driving wheel and may be a four-wheel driving vehicle. . 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.

  As mentioned above, although embodiment of this invention was described with reference to drawings, this invention is not limited to the thing of embodiment shown in figure. Various modifications and variations can be made to the illustrated embodiment within the same range or equivalent range as the present invention.

It is a figure which shows the in-wheel motor drive device which concerns on one Embodiment of this invention. It is sectional drawing in II-II of FIG. It is an enlarged view of the eccentric part periphery of FIG. FIG. 2 is an enlarged view around an inner pin in FIG. 1. It is a figure which shows other embodiment of an inner pin. It is a figure which shows the in-wheel motor drive device which concerns on other embodiment of this invention. It is a top view of the electric vehicle which has the in-wheel motor drive device of FIG. FIG. 8 is a rear sectional view of the electric vehicle of FIG. 7. It is a figure which shows the conventional in-wheel motor drive device.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 Electric vehicle, 12 Chassis, 12a Wheel housing, 12b Suspension device, 13 Front wheel, 14 Rear wheel, 21,101 In-wheel motor drive device, 22,102 Casing, 22a Outer member, 22b Lubricating oil discharge port, 22c Circulating oil Road, 23 Stator, 24 Rotor, 24a Rotor part, 28a, 32b Flange part, 24b, 32a Hollow part, 28b Shaft part, 25, 106 Motor side rotating member, 25a, 25b, 106a, 106b Eccentric part, 25c Lubricating oil path , 25d Lubricating oil supply port, 25e Expanded diameter part, 25f Steel ball, 26a, 26b, 107a, 107b Curved plate, 27, 42, 108 Outer pin, 27a, 31a, 41a, 42c Cylindrical member, 28, 110 Wheel side rotation Member, 29 counterweight, 30a, 30b through hole, 31 41, 109 Inner pin, 27b, 31b, 41b, 41c, 42d Dynamic pressure groove, 42a Large diameter portion, 42b Small diameter portion, 32 Wheel hub, 32c, 32d Bolt, 33g, 35, 39 Seal member, 33 Wheel hub bearing 33a, 33b Outer raceway surface, 33c, 33d Inner raceway surface, 33e Ball, 33f Cage, 33h Inner ring member, 34, 36a, 36b, 108a, 109a, 111 Rolling bearing.

Claims (6)

A casing,
An input shaft having an eccentric portion;
A revolving member having a through-hole through which the eccentric portion is inserted, and performing a revolving motion around the rotation axis as the input shaft rotates;
An outer periphery engaging member that is held by the casing and engages with an outer peripheral portion of the revolving member to cause rotation of the revolving member;
An inner pin provided on the output shaft, formed on the revolving member, having a diameter larger than the outer diameter of the inner pin by a predetermined amount and receiving the inner pin, and the inner pin at a position in contact with the inner wall surface of the hole A cylindrical member that fits into the pin, and a motion conversion mechanism that converts the rotational motion of the revolving member into a rotational motion around the rotational axis of the input shaft and transmits the rotational motion to the output shaft,
The inner pin and the cylindrical member are fitted with a predetermined radial gap, and a dynamic pressure groove is formed on one of the outer diameter surface of the inner pin and the inner diameter surface of the cylindrical member. A cycloid reducer that constitutes a bearing. The outer periphery engaging member has an outer pin fixed to the casing, and a cylindrical member fitted to the outer pin at a position in contact with the outer periphery of the revolving member,
The outer pin and the cylindrical member are fitted with a predetermined radial gap, and a dynamic pressure groove is formed on one of the outer diameter surface of the outer pin and the inner diameter surface of the cylindrical member. The cycloid reducer according to claim 1, comprising a bearing. The outer peripheral engagement member has an outer pin that engages with an outer peripheral portion of the revolving member, and a cylindrical member that is fixed to the casing and receives the outer pin on an inner diameter surface,
The outer pin and the cylindrical member are fitted with a predetermined radial gap, and a dynamic pressure groove is formed on one of the outer diameter surface of the outer pin and the inner diameter surface of the cylindrical member. The cycloid reducer according to claim 1, comprising a bearing.   The cycloid reducer according to claim 1, wherein the dynamic pressure groove is formed by rolling.   The cycloid reduction gear according to any one of claims 1 to 4, wherein the cylindrical member is a sintered alloy formed by powder metallurgy. A motor unit that rotationally drives a motor-side rotating member as an input shaft;
The cycloid reducer according to any one of claims 1 to 5, wherein the rotation of the motor side rotation member is decelerated and transmitted to a wheel side rotation member as an output shaft,
An in-wheel motor drive device comprising: a wheel hub fixedly connected to the wheel side rotation member.

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