WO2012128003A1 - Cycloid decelerator and in-wheel motor drive device - Google Patents

Abstract

The present invention achieves a configuration of a cycloid decelerator and an in-wheel motor drive device using the same wherein a retainer of a needle roller bearing that supports an external pin is prevented from coming out, without increasing cost or housing size. In the cycloid decelerator, an engagement flange section (53) that curves radially inward is provided on the outer edge of a retainer (48) of a needle roller bearing (43) that supports an external pin (31), and this engagement flange section (53) is engaged in the axial direction with the outer end face of the external pin (31) so as to prevent the retainer (48) from coming out.

Description

Cycloid reducer and in-wheel motor drive device

The present invention relates to a cycloid reduction gear and an in-wheel motor drive device using the same, and more particularly to a support bearing for an outer pin in a cycloid reduction gear.

Conventionally, it is known to use a cycloid reducer as a reducer suitable for constituting a reduction part of an in-wheel motor drive device. The cycloid reducer generally includes an eccentric cam provided on an input shaft, a curved plate that is rotatably fitted to the outer peripheral surface of the eccentric cam and has an arc gear on the outer peripheral portion, and the outer side in the radial direction of the curved plate. An annular outer pin housing provided on the inner peripheral surface of the housing concentrically with the input shaft, an outer pin held by the outer pin housing and engaged with the arc gear, and the rotational movement of the curved plate as an output member And a motion conversion mechanism for transmission. Both end portions of the outer pin are supported by the outer pin housing via a rolling bearing (Patent Document 1).

The cycloid reducer is compact but has the advantage of obtaining a high reduction ratio. On the other hand, when the reduction ratio is n, the number of external pins is (n-1). For this reason, if the bearing which supports an outer pin becomes large, an outer pin housing and by extension, a housing of a reduction gear will enlarge. In consideration of this point, it is conventionally known to use a needle roller bearing as the bearing (Patent Document 2).

JP 2008-44537 A JP 2010-48280 A

The needle roller bearing 111 includes a needle roller 112, a cage 113, and an outer ring 114 as shown in FIG. The needle roller bearing 111 is interposed between both ends of the outer pin 118 and the hole 117 of the outer pin housing 115 that supports the outer pin 118.

The outer pin housing 115 is fitted and fixed to the inner surface of the reduction gear housing 119. The needle roller bearing 111 reduces the friction in the radial direction of the outer pin 118, and a steel ball 120 is interposed between the end surface of the outer pin 118 and the speed reducer housing 119. Friction can be reduced. A thrust plate 121 may be embedded in the contact surface of the steel ball 120. Further, the flange portion of the clip 122 engaged with the outer pin housing 115 is engaged with the inner end surface of the outer ring 114, so that the outer ring 114 is prevented from coming off.

According to the support structure of the outer pin 118, the cage 113 of the needle roller bearing 111 is prevented from moving by the wall of the speed reducer housing 119 to the outside in the axial direction, but is obstructed to the inside in the opposite direction. Therefore, the cage 113 may come out together with the needle rollers 112 when subjected to vibration, impact, or the like.

As a measure for preventing the slipping out, there is means for providing a stepped portion 123 having a large diameter on the inner side in the axial direction as shown in FIG. However, the provision of the stepped portion 123 on the outer pin 118 increases the manufacturing process and increases the inspection time for managing the outer diameter, which increases the cost.

Also, as shown in FIG. 10, there are means for providing flange portions 124, 124 on the inner diameter surfaces of both ends of the outer ring 114, thereby engaging both ends of the cage 113. However, the outer ring 114 becomes thick, which causes the reduction gear housing 119 to increase in size.

Therefore, the present invention is accompanied by an increase in cost and an increase in the size of the housing in the cycloid speed reducer and the in-wheel motor drive device using the same, which prevents the retainer of the needle roller bearing that supports the outer pin from coming out. It is a problem to realize without.

In order to solve the above problems, the present invention includes an eccentric cam provided on an input shaft, a curved plate that is rotatably fitted to an outer peripheral surface of the eccentric cam and has an arc gear on the outer peripheral portion, and the arc gear. A cycloid formed by a required number of outer pins that engage with the needle, a needle roller bearing that rotatably supports the outer pins with respect to the housing, and a motion conversion mechanism that transmits the rotational motion of the curved plate to an output member. In the speed reducer, the retainer of the needle roller bearing is provided with an engaging portion, and the engaging portion is engaged in the axial direction with a fixing member that is radially adjacent to the retainer and fixed in the axial direction. Was adopted.

Here, the “engagement portion” of the cage specifically refers to an engagement collar portion formed by bending the outer edge of the cage toward the inner diameter side or the outer diameter side. The “fixing member radially adjacent to the cage and fixed in the axial direction” specifically refers to an outer pin or an outer ring. When the engagement flange portion is bent toward the inner diameter side, the outer pin corresponds, and the engagement flange portion is engaged with the outer end surface of the outer pin. Further, when the engagement flange portion is bent toward the outer diameter side, the outer ring corresponds, and the engagement flange portion is engaged with the outer end surface of the outer ring.

As described above, according to the present invention, in the cycloid reducer and the in-wheel motor drive device using the same, the engaging portion is provided in the cage of the needle roller bearing that supports the outer pin, and the engaging portion is used as a fixing member. By adopting the configuration in which the cage is engaged in the axial direction, the retainer can be prevented from coming off. According to this configuration, there is no increase in the number of parts or processing steps, so that the manufacturing cost and the size of the housing are not affected. Providing the engaging portion in the cage can be realized only by changing the shape of the conventional cage, so that there is an advantage that the conventional manufacturing process of the needle roller bearing does not need to be significantly changed.

FIG. 1 is a cross-sectional view of an in-wheel motor drive device. FIG. 2 is an enlarged cross-sectional view of the deceleration portion same as above. 3 is a cross-sectional view taken along line X1-X1 of FIG. 4 is an enlarged cross-sectional view of the outer pin support portion of FIG. 5 is a partially enlarged cross-sectional view of another example 1 of the outer pin support portion of FIG. 6 is a partially enlarged cross-sectional view of another example 2 of the outer pin support portion of FIG. 7 is a partially enlarged cross-sectional view of another example 3 of the outer pin support portion of FIG. 8 is a partially enlarged cross-sectional view of another example 4 of the outer pin support portion of FIG. FIG. 9 is an enlarged cross-sectional view of a conventional outer pin support portion. FIG. 10 is a partially enlarged cross-sectional view of another example of a conventional outer pin support portion.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

As shown in FIG. 1, the in-wheel motor drive device 11 according to the embodiment of the present invention 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 a deceleration unit. A wheel hub bearing portion C that transmits the output of the portion B to the wheels is provided. The motor part A is incorporated in the motor housing 12, and the reduction part B is incorporated in the reduction part housing 13. A speed reduction unit housing 13 is connected and fixed to the front end of the motor housing 12 by a bolt 14.

The motor part A includes a stator 15 fixed to the motor housing 12 and a rotor 17 integrated with the motor shaft 16, and the stator 15 and the rotor 17 constitute a radial gap motor opposed to each other in the radial direction. The rotor 17 is fixed to the flange 19 of the motor shaft 16 by bolts 18. The motor shaft 16 is rotatably supported by the motor housing 12 via rolling bearings 21a and 21b at both front and rear ends.

The motor shaft 16 is provided with an internal passage 22, and the input shaft 23 of the speed reduction portion B is connected to the front end of the internal passage 22. The input shaft 23 is also provided with an internal passage 25, and both the internal passages 22 and 25 communicate with each other.

The reduction part B is comprised by the cycloid reduction gear which is the object of this invention. The speed reduction part B includes an annular outer pin housing 26 fitted and fixed concentrically with the input shaft 23 on the inner diameter surface of the speed reduction part housing 13 (see FIGS. 1 and 2), and each member constituting the speed reduction part B Is provided on the inner diameter side of the outer pin housing 26.

As a member constituting the speed reduction portion B, a pair of eccentric cams 27a and 27b provided adjacent to each other in the axial direction on the input shaft 23, and the eccentric cams 27a and 27b via cylindrical roller bearings 28a and 28b. Rotating curved plates 29a and 29b, a plurality of outer pins 31 (see FIG. 3) fixed at equal intervals along the inner diameter surface of the outer pin housing 26, and the rotational motion of the curved plates 29a and 29b are output members. There is a motion conversion mechanism 20 constituted by an inner pin 34 that transmits to 32 and its through hole 39, counterweights 33a, 33b attached to the input shaft 23 adjacent to the outer side in the axial direction of the eccentric cams 27a, 27b, etc. .

The eccentric cams 27a and 27b are provided with a 180 ° phase change so as to cancel out centrifugal forces due to the eccentric motion.

The output member 32 has a flange portion 32a and a shaft portion 32b (see FIG. 2). One end portions of a plurality of inner pins 34 are inserted into and fixed to the flange portion 32a at equal intervals on the circumference around the rotation axis of the output member 32. The shaft portion 32b is fitted and fixed to the inner diameter surface of the wheel hub 35, and transmits the output of the speed reduction portion B to the wheel. A rolling bearing 36 is interposed between the inner diameter surface of the flange portion 32a of the output member 32 and the input shaft 23, so that the input shaft 23 and the output member 32 are held concentrically and are relatively rotatable.

The other end portion of the inner pin 34 is inserted and supported by a flange portion 37a of the stabilizer 37 (see FIG. 2). The stabilizer 37 has a cylindrical portion 37b provided on the inner diameter of the flange portion 37a, and the cylindrical portion 37b has a front end portion (end portion on the speed reduction portion B side) outer diameter of the motor shaft 16 through a needle roller bearing 38. The surface is rotatably fitted.

As shown in FIG. 3, the curved plates 29a and 29b have an arc gear 30 formed of a trochoidal curve such as epitrochoid on the outer peripheral portion, and a plurality of penetrating holes penetrating from one end surface to the other end surface in the axial direction. A hole 39 is provided. The through holes 39 are provided in the same number and at the same intervals as the inner pins 34 on the circumference around the rotation axis of the curved plates 29a and 29b, and the inner pins 34 are provided in the respective through holes 39. It is inserted with a margin in the radial direction (twice the amount of eccentricity).

The curved plates 29a and 29b are rotatably supported by the eccentric cams 27a and 27b via cylindrical roller bearings 28a and 28b, respectively. The phases of the curved plates 29a and 29b are also shifted by 180 ° in the same direction as the eccentric cams 27a and 27b.

In order to cancel out the unbalanced inertia couple generated by the rotation of the eccentric cams 27a and 27b and the curved plates 29a and 29b, counterweights 33a and 33b are provided adjacent to the outer sides in the axial direction of the eccentric cams 27a and 27b. These counterweights 33a and 33b are attached to the eccentric cams 27a and 27b in an eccentric state in which the phase is changed by 180 °.

The outer pin housing 26 is formed in an annular shape (see FIG. 3), and is provided with holes 26a, 26b corresponding to the number of outer pins 31, respectively, at regular intervals in the circumferential direction. Both end portions of the outer pin 31 are inserted into the holes 26 a and 26 b and supported by the speed reduction unit housing 13 through the needle roller bearings 43. The number of the outer pins 31 is one more than the number of teeth of the arcuate gears 30 of the curved plates 29a and 29b, and a plurality of outer pins 31 are simultaneously engaged with the arcuate gears 30.

The above-described motion conversion mechanism 20 includes a plurality of inner pins 34 fixed to the output member 32 and through holes 39 provided in the curved plates 29a and 29b. The inner diameter dimension of the through-hole 39 is only twice the eccentric amount of the eccentric cams 27a and 27b from the outer diameter dimension of the inner pin 34 (referred to as "the maximum outer diameter including the needle roller bearings 46a and 46b"). It is set large. The inner pin 34 partially contacts the inner wall surface of the through hole 39 as the curved plates 29a and 29b rotate. As a result, the revolving motion of the curved plates 29 a and 29 b is not transmitted to the inner pin 34, but the motion converted into only the rotational motion is transmitted to the inner pin 34.

The inner pins 34 are provided at equal intervals on a circumferential track centering on the rotational axis of the output member 32. As described above, one end of the inner pin 34 is fixed to the output member 32, and the other end. Is fixed to the stabilizer 37. In order to reduce the frictional resistance with the curved plates 29a, 29b, needle roller bearings 46a, 46b are provided in portions of the curved plates 29a, 29b that pass through the through holes 39, and each inner pin 34 has its needle roller bearing. It partially contacts the through hole 39 via 46a and 46b.

As shown in FIG. 4, the needle roller bearing 43 that rotatably supports the outer pin 31 is a combination of a needle roller 47, its retainer 48, and an outer ring 49. The holes 26a and 26b are fitted. In order to prevent the outer ring 49 from coming off, the flange 52 of the clip 51 engaged with the outer pin housing 26 is engaged with the inner end surface of the outer ring 49. By the engagement, the outer ring 49 is prevented from moving in the axial direction with respect to the outer pin housing 26 and is fixed.

Further, pockets 40 are provided at both ends of the outer pin 31, and the steel balls 44 held in the pockets 40 are abutted against the inner surface of the speed reduction unit housing 13. Thereby, the friction in the thrust direction of the outer pin 31 is reduced. A thrust plate 45 is embedded in the inner surface of the speed reduction unit housing 13 that is in contact with the steel ball 44. The steel ball 44 may be brought into direct contact with the inner surface of the speed reduction unit housing 13 (see FIG. 5).

When the steel ball 44 protrudes from the end face of the outer pin 31, a certain axial gap a is formed between the end face of the outer pin 31 and the speed reduction unit housing 13 (see FIG. 4).

The outer edge of the retainer 48 (the side edge on the outer end side of the outer pin 31) is formed with a larger width in the axial direction than usual, and a portion that does not impair the original function of the retainer is bent toward the inner diameter side. By doing so, the engagement flange 53 is formed. The engagement flange 53 is interposed in a gap a between the end surface of the outer pin 31 and the inner surface of the speed reduction unit housing 13 facing the outer pin 31, and is adjacent to the outer pin 31 (that is, the inner diameter side of the cage 48). The outer end surface of the fixing member is engaged in the axial direction.

Since the relationship between the outer diameter D1 of the outer pin 31 and the inner diameter d1 of the engagement flange 53 is D1> d1, the engagement flange 53 is engaged with the outer pin 31 in the axial direction, and the cage 48 Pulling out to the inside is prevented.

The gap a is formed to be slightly larger than the thickness of the engagement flange portion 53 so that the engagement flange portion 53 can rotate relative to the outer pins 31 and the speed reduction portion housing 13 on both sides thereof. Further, the outer end portion of the outer ring 49 is formed longer than usual so that it can abut against the inner surface of the speed reduction unit housing 13 so that the outer ring 49 can be easily positioned in the axial direction.

In the case of FIG. 6, the needle roller bearing 43 is constituted by the needle roller 47 and its retainer 48, and there is no outer ring 49 as described above. In this case, the inner diameter surfaces of the holes 26 a and 26 b of the outer pin housing 26 become rolling surfaces of the needle rollers 47. The engaging flange 53 bent to the inner diameter side is formed at the outer edge of the cage 48 and is engaged with the outer end surface of the outer pin 31 in the axial direction as in the case described above.

In the case of FIG. 7, the engagement flange 53 is formed by bending the outer edge of the cage 48 in the outer diameter direction. The engagement flange 53 is interposed in a portion of a gap a between the outer ring 49 and the speed reduction unit housing 13, and engages with the outer ring 49 which is a fixing member adjacent to the outer diameter side of the cage 48 in the axial direction. Is done. Other configurations are the same as those in FIGS. 5 and 6.

In this case, since the relationship between the inner diameter d2 of the outer ring 49 and the outer diameter of the engagement flange 53 is D2 <D2, the engagement flange 53 is engaged with the outer ring 49 in the axial direction and held. The escape to the inside of the vessel 48 is prevented.

In the other example shown in FIG. 8, the engagement flange 53 is bent in the outer diameter direction as in the case of FIG. 7, but the outer end surface of the outer pin 31 is formed into a spherical surface or an arc surface. The surface is directly pressed against the inner surface of the speed reduction unit housing 13.

In each of the examples described above, the retainer 48 may be either a resin manufactured by injection molding or cutting, or a metal manufactured by pressing or welding. In the case of a pressed metal cage, surface modification such as plating for improving the coefficient of friction and improving wear resistance may be performed on the surface.

As a mechanism for supplying lubricating oil to the speed reduction portion B, a rotary pump 55 (see FIGS. 1 and 2) is provided on the outer diameter surface of the cylindrical portion 37b of the stabilizer 37 in the inner diameter portion of the wall surface of the motor housing 12 on the speed reduction portion B side. An oil supply passage 56 that is provided and reaches the inside of the speed reduction portion B and a return passage 57 that finishes lubrication and returns from the speed reduction portion B are provided.

The oil supply passage 56 reaches the rear end of the motor shaft 16 along the inner side of the motor housing 12, and corresponds to the internal passages 22 and 25 of the motor shaft 16 and the input shaft 23 and the eccentric cams 27a and 27b of the input shaft 23. The oil supply holes 58a and 58b (see FIG. 2) provided in the radial direction at the position are reached, and the lubricating oil is supplied into the speed reduction unit B through this path. The returned lubricating oil returns to the rotary pump via the return passage 57 from the lubricating oil reservoir 59 provided on the outer bottom of the speed reduction unit housing 13.

As shown in FIG. 1, the wheel hub bearing portion C includes a wheel hub 35 fixedly connected to the output member 32 of the speed reduction portion B, and a wheel hub bearing 60 that rotatably holds the wheel hub 35 with respect to the speed reduction portion housing 13. Is provided. The output member 32 is inserted into the inner diameter surface of the wheel hub 35 and splined, and the tip of the output member 32 exposed from the wheel hub 35 is fastened with a nut 50 to connect the output member 32 and the wheel hub 35. ing.

Next, the operation principle of the in-wheel motor drive device 11 having the above configuration will be described. The motor unit A receives an electromagnetic force generated by supplying an alternating current to the coil of the stator 15, and the rotor 17 constituted by a permanent magnet or a magnetic material rotates.

As a result, when the motor shaft 16 connected to the rotor 17 and the input shaft 23 integrated therewith rotate, the eccentric cams 27a and 27b perform eccentric rotational movement, so that the curved plates 29a and 29b become the rotational axis of the input shaft 23. The revolving motion is performed at the speed of the input shaft 23 around the center. At this time, the plurality of outer pins 31 engage with the arcuate gears 30 of the curved plates 29a and 29b to cause the curved plates 29a and 29b to rotate at a low speed in the direction opposite to the rotation direction of the input shaft 23. .

The inner pin 34 inserted through the through-hole 39 partially contacts the inner wall surface of the through-hole 39 as the curved plates 29a and 29b rotate. As a result, the revolving motion of the curved plates 29a, 29b is not transmitted to the inner pin 34, but is converted into only the rotational motion of the curved plates 29a, 29b. It is transmitted to the bearing portion C.

Thus, since the rotation of the motor shaft 16 is decelerated by the speed reduction part B and transmitted to the wheel hub bearing part C via the output member 32, even when the low torque, high speed type motor part A is adopted, It is possible to transmit the necessary torque to the wheels.

The reduction ratio of the reduction part B having the above-described configuration is calculated as (ZA−ZB) / ZB, where ZA is the number of outer pins 31 and ZB is the number of arc gears 30 of the curved plates 29a and 29b. In the embodiment shown in FIG. 1, since ZA = 12, ZB = 11, the reduction ratio is 1/11, and a very large reduction ratio can be obtained.

In this way, by adopting the reduction part B that can obtain a large reduction ratio without using a multistage configuration, the in-wheel motor drive device 11 having a compact and high reduction ratio can be obtained. In addition, since the outer pin 31 is supported by the needle roller bearing 43 and the needle roller bearings 46a and 46b are provided at positions where they contact the curved plates 29a and 29b of the inner pin 34, the frictional resistance is reduced. The transmission efficiency of the deceleration part B is improved.

Further, the retainer 48 of the needle roller bearing 43 that supports the outer pin 31 has an engagement flange portion 53 provided on the outer end edge thereof in the radial direction with respect to the outer pin 31 or the outer ring 49 (that is, the retainer 48 in the radial direction). By engaging with a fixing member which is adjacent and fixed in the axial direction, it is prevented from coming out in the axial direction.

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.

A Motor part B Reduction part C Wheel hub bearing part 11 In-wheel motor drive device 12 Motor housing 13 Reduction part housing 14 Bolt 15 Stator 16 Motor shaft 17 Rotor 18 Bolt 19 Flange 20 Motion conversion mechanism 21a, 21b Rolling bearing 22 Internal passage 23 Input shaft 25 Internal passage 26 Outer pin housing 26a, 26b Hole 27a, 27b Eccentric cam 28a, 28b Cylindrical roller bearings 29a, 29b Curved plate 30 Arc gear 31 Outer pin 32 Output member 32a Flange part 32b Shaft part 33a, 33b Counterweight 34 Inner pin 35 Wheel hub 36 Rolling bearing 37 Stabilizer 37a Flange portion 37b Cylindrical portion 38 Needle roller bearing 39 Through hole 40 Pocket 43 Needle roller bearing 44 Steel ball 45 Thrust plate 46a, 46b Needle Roller bearings 47 Needle roller 48 cage 49 outer ring 50 Nut 51 Clip 52 flange portion 53 engaging flange portion 55 rotates the pump 56 oil supply passage 57 return passage 58a, 58b oil supply hole 59 lubricating oil storage portion 60 a wheel hub bearing

Claims (10)

1. An eccentric cam provided on the input shaft; a curved plate rotatably fitted to the outer peripheral surface of the eccentric cam; and an outer peripheral portion having an arc gear; a required number of outer pins engaged with the arc gear; and the outer pin In a cycloid reducer comprising a needle roller bearing that rotatably supports the housing and a motion conversion mechanism that transmits the rotational motion of the curved plate to an output member, the cage of the needle roller bearing A cycloid speed reducer characterized in that an engaging portion is provided, and the engaging portion is axially engaged with a fixing member that is radially adjacent to the retainer and fixed in the axial direction.
2. 2. The cycloid according to claim 1, wherein the engagement portion is an engagement flange portion formed by bending an outer edge of the cage toward an inner diameter side, and the fixing member is the outer pin. Decelerator.
3. The engagement structure between the engagement flange portion and the outer pin end surface is a structure in which a predetermined gap is provided between the outer end surface of the outer pin and the housing, and the engagement flange portion is interposed between the clearances. The cycloid reduction gear of Claim 2 characterized by the above-mentioned.
4. The cycloid reducer according to claim 3, wherein the predetermined gap is formed to be larger than the thickness of the engagement flange portion.
5. The cycloid reducer according to any one of claims 1 to 4, wherein the needle roller bearing is constituted by a needle roller and a cage thereof, and a rolling surface is formed on the housing side.
6. The said engaging part is an engaging collar part formed by bending the outer edge of the said holder | retainer to the outer-diameter side, The said fixing member is the said outer ring | wheel, The said outer ring | wheel is characterized by the above-mentioned. Cycloid reducer.
7. The engagement structure between the engagement flange portion and the outer ring end surface is a structure in which a predetermined gap is provided between the outer end surface of the outer ring and the housing, and the engagement flange portion is interposed between the gaps. The cycloid reducer according to claim 6, wherein
8. The cycloid reducer according to claim 7, wherein the predetermined gap is formed to be larger than a thickness of the engagement flange portion.
9. An annular outer pin housing is fixed to the housing concentrically with the input shaft, and both ends of the outer pin are inserted into holes provided in the outer pin housing, and the needle is interposed between the outer pin and the hole. The cycloid reduction gear according to any one of claims 1 to 8, wherein a roller bearing is interposed, and the outer pin is supported by the housing via an outer pin housing.
10. An in-wheel comprising a motor unit, a deceleration unit that decelerates the output rotation of the motor unit, a housing that holds the motor unit and the deceleration unit, and a wheel hub bearing unit that is connected and fixed to an output member of the deceleration unit The in-wheel motor drive device characterized by using the cycloid reducer in any one of Claim 1 to 9 as the said deceleration part in a motor drive device.

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