JP2020040488A - Electric vehicle drive device and in-wheel motor drive device - Google Patents

Abstract

To provide an electric vehicle drive device which can reduce the vibration and noise between gears by reducing the misalignment that may occur in a gear shaft.SOLUTION: A deceleration mechanism unit includes: a parallel shaft gear mechanism which has triaxial gear shafts 27, 28, 29 arranged in parallel with each other; a first casing which is provided with a bearing supporting one end parts of the gear shafts 27, 28, 29; and a second casing which is provided with a bearing supporting other end parts of the gear shafts 27, 28, 29, and is configured such that the first casing and the second casing are positioned by a pair of knock pins 80. Each knock pin 80 is arranged so that a line segment connecting the center of each knock pin 80 passes through any two of intersection points between respective apexes and respective sides of triangles formed by connecting shaft centers O1, O2, O3 of the gear shafts 27, 28, 29 when viewed from the axial direction.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a driving device for an electric vehicle in which wheels are driven by an electric motor, and an in-wheel motor driving device that is disposed in an inner space area of the wheels and drives the wheels.

  2. Description of the Related Art As a drive device used for an electric vehicle, there is known a drive device provided with a reduction unit (reduction device) having a plurality of gear shafts arranged in parallel with each other.

  For example, Patent Literature 1 below has an input shaft (a motor rotation shaft provided with an input gear), an intermediate shaft, and an output shaft (a cylinder portion provided with an output gear) arranged in parallel with each other. An in-wheel motor drive provided with a speed reduction unit is disclosed.

JP 2017-65306 A

  In a drive device using such a speed reducer having a plurality of gear shafts, misalignment of the gear shaft (gear shaft misalignment) occurs due to a load between the gears, an assembling error of a casing that supports the gears, or a machining error of the casing. Relative inclination between the two) occurs. When the misalignment of the gear shaft becomes large, vibration and noise are generated due to the transmission error of the meshing between the gears (delay or advance of the relative rotation of the driven gear with respect to the driving gear). There is a possibility that the parts may be deteriorated or damaged.

  The misalignment of the gear shaft caused by the gear load can be calculated by a finite element method (FEM). For this reason, if the gear load is known in advance, it is possible to calculate the misalignment caused by this, and adjust the meshing state of the gears by performing tooth surface correction (crowning processing) based on the misalignment.

  On the other hand, the misalignment of the gear shaft caused by the assembly error and the processing error of the casing is often indeterminate in the direction and amount of the error, and is difficult to calculate in advance.

  Therefore, it is a very important task to reduce the misalignment of the gear shaft caused by the assembly error and the processing error of the casing. Note that such a problem is not limited to the in-wheel motor, but may also occur in a so-called on-board type electric vehicle drive device having an electric motor provided on a vehicle body.

  Accordingly, an object of the present invention is to provide an electric vehicle drive device and an in-wheel motor drive device that can reduce misalignment that can occur on a gear shaft and reduce vibration and noise between gears.

  In order to solve the above-described problems, the present invention provides an electric vehicle drive device including an electric motor unit, a wheel bearing unit, and a speed reducer unit that transmits torque from the electric motor unit to the wheel bearing unit. The unit supports a parallel shaft gear mechanism having three or more gear shafts arranged in parallel with each other, a first casing provided with a bearing for supporting one end of the gear shaft, and supporting the other end of the gear shaft. A second casing provided with a bearing, wherein the first casing and the second casing are positioned by a pair of knock pins, and a line connecting the centers of the knock pins when viewed from the axial direction is formed by each gear. Each of the knock pins is disposed so as to pass through any two of the vertices of the polygon formed by connecting the axis centers of the axes and the intersections with the respective sides.

  In this way, when viewed from the axial direction, a line segment connecting the centers of the knock pins defines any two of the intersections with the vertices and sides of the polygon formed by connecting the axis centers of the gear shafts. By passing through, the knock pins can be arranged at two relatively distant points on the casing. As a result, the positioning accuracy by the knock pin is improved, so that misalignment in each gear shaft can be reduced.

  For example, when viewed from the axial direction, a line connecting the centers of the knock pins passes through two vertexes of a polygon formed by connecting the centers of the gear shafts, so that the casing is relatively far away. Knock pins can be arranged at two points.

  Also, when viewed from the axial direction, each knock pin is inserted so that a line connecting the centers of the knock pins passes through the intersection of one vertex and one side of a polygon formed by connecting the axis centers of the gear shafts. May be arranged.

  Alternatively, each knock pin is arranged such that a line segment connecting the centers of the knock pins passes through an intersection with two sides of a polygon formed by connecting the axis centers of the respective gear shafts when viewed from the axial direction. Is also good.

  According to another aspect of the present invention, there is provided an electric vehicle driving apparatus including an electric motor unit, a wheel bearing unit, and a speed reducer unit that transmits torque from the electric motor unit to the wheel bearing unit. , The reduction gear unit comprises a parallel shaft gear mechanism having three or more gear shafts arranged in parallel with each other, a first casing provided with a bearing for supporting one end of the gear shaft, and a second end of the gear shaft. A second casing provided with a bearing for supporting the portion, wherein the first casing and the second casing are positioned by a pair of knock pins, and a line segment connecting the centers of the knock pins when viewed from the axial direction. The distance from the intermediate point to the center of each gear shaft is set based on the magnitude of misalignment of each gear shaft.

  By adjusting the distance from the midpoint of the line segment connecting the centers of the knock pins to the shaft center of each gear shaft, the relative magnitude relationship of misalignment that can occur in each gear shaft due to positional displacement between the casings is appropriately set. be able to. Therefore, the magnitude of the misalignment that can occur on each gear shaft is predicted by prior analysis, and the distance from the midpoint of the line connecting the centers of the knock pins to the shaft center of each gear shaft is set based on the misalignment. By doing so, it is possible to prevent misalignment that can occur in a specific gear shaft from becoming larger than misalignment that can occur in another gear shaft. This makes it possible to suppress the occurrence of vibration and noise due to an increase in misalignment in some gear shafts.

  For example, among the plurality of gear shafts, when the misalignment that can occur in some of the gear shafts is the largest, when viewed from the axial direction, the axis of each gear shaft starts from the midpoint of the line connecting the centers of the knock pins. The distance to the center is preferably set to be minimum with respect to the gear axis where the misalignment is greatest. By setting in this way, the misalignment of the gear shaft caused by the misalignment between the casings can be reduced for the gear shaft expected to have the largest misalignment as compared with other gear shafts. In particular, it is possible to prevent the misalignment occurring on the gear shaft from becoming particularly large.

  Further, when viewed from the axial direction, the distance from the midpoint of the line segment connecting the centers of the knock pins to the shaft center of each gear shaft may be set to be the same distance in all or a part. In other words, if there are gear shafts having the same degree of misalignment among a plurality of gear shafts, the distance from the midpoint between the knock pins to the shaft center of those gear shafts should be the same. By setting, variations in misalignment that can occur in each gear shaft can be eliminated and made uniform.

  Further, the parallel shaft gear mechanism has an input shaft having an input gear to which torque from the electric motor unit is input, an output shaft connected to the wheel bearing unit, and having an output gear, and an input shaft and an output shaft. The input shaft is configured with one or more intermediate shafts that perform power transmission by meshing via gears.The intermediate shaft has a larger diameter than the input gear and meshes with the input gear, and a smaller diameter than the output gear. And an output-side intermediate gear that meshes with the output gear.

  The present invention is also applicable to an in-wheel motor drive.

  According to the present invention, a possible misalignment of the gear shaft can be reduced, so that vibration and noise between the gears can be reduced. Further, by reducing the misalignment, the amount of gear tooth surface correction can be reduced, and the time and cost required for processing can be reduced.

FIG. 3 is a vertical cross-sectional view of the in-wheel motor drive device when viewed from a line PP in FIG. 2. FIG. 2 is a transverse cross-sectional view of the in-wheel motor driving device when viewed in the direction of arrows QQ in FIG. 1. FIG. 3 is a longitudinal sectional view in which a part of the in-wheel motor drive device is exploded. It is a cross-sectional view showing arrangement of a knock pin concerning a 1st example. It is a figure which shows the relationship between the distance from the midpoint of knock pins to the center of a knock pin, and a position shift angle. It is a cross-sectional view showing the arrangement of the knock pin according to the second embodiment. It is a cross-sectional view showing arrangement of a knock pin according to a third embodiment. It is a cross-sectional view showing arrangement of a knock pin according to a fourth embodiment. It is a cross-sectional view showing arrangement of a knock pin according to a fifth embodiment. It is a top view showing the schematic structure of the electric vehicle carrying the in-wheel motor drive. FIG. 11 is a rear sectional view showing the electric vehicle of FIG. 10.

  Hereinafter, the present invention will be described with reference to the accompanying drawings. In each of the drawings for describing the present invention, components such as members and components having the same function or shape are denoted by the same reference numerals as much as possible, and once described, the description is omitted. Omitted.

  In the following description, an example is described in which the present invention is applied to an in-wheel motor drive device arranged in an inner space area of a wheel. However, the present invention is not limited to the in-wheel motor drive device, and the drive device is a vehicle body. The present invention can also be applied to a so-called on-board type electric vehicle drive device provided in the vehicle. Further, the on-board type may be either a one-motor type in which one electric motor drives left and right wheels and a two-motor type in which two electric motors drive left and right wheels.

  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 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 driving wheel, and an in-wheel motor driving device 21 that transmits driving force to the rear wheel 14. To equip. As shown in FIG. 11, the rear wheel 14 is housed inside a wheel housing 15 of the chassis 12 and is fixed to a lower portion of the chassis 12 via a suspension 16.

  The suspension device 16 supports the rear wheel 14 with a suspension arm extending left and right, and absorbs vibration received by the rear wheel 14 from the ground by a strut including a coil spring and a shock absorber to suppress the vibration of the chassis 12. A stabilizer is provided at a connection portion between the left and right suspension arms to suppress a tilt of the vehicle body during turning or the like. The suspension device 16 is of an independent suspension type in which the left and right wheels are moved up and down independently in order to improve the ability to follow the unevenness of the road surface 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 for driving the right and left rear wheels 14 inside the wheel housing 15, 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 large cabin space can be secured and the rotation of the left and right rear wheels 14 can be controlled.

  Before describing the characteristic configuration of this embodiment, the overall configuration of the in-wheel motor drive device 21 will be described with reference to FIGS. In the following description, when the in-wheel motor drive device 21 is mounted on the vehicle, the side (left side in FIG. 1) that is closer to the outside in the vehicle width direction is called the outboard side, and the side closer to the center (see FIG. 1). 1 is called the inboard side.

  FIG. 1 is a longitudinal sectional view of the in-wheel motor drive device taken along the line PP of FIG. 2, and FIG. 2 is a cross-sectional view of the in-wheel motor drive device taken along the line QQ of FIG. FIG. 3 and FIG. 3 are longitudinal sectional views in which a part of the in-wheel motor driving device is exploded.

  As shown in FIG. 1, the in-wheel motor drive device 21 includes an electric motor unit A that generates a driving force, a speed reducer unit B that reduces the speed of rotation of the electric motor unit A, and outputs a signal. And a wheel bearing portion C for transmitting the output to the rear wheel 14 as a drive wheel. The electric motor portion A, the speed reducer portion B, and the wheel bearing portion C are accommodated in a first casing 22a and a second casing 22b, respectively, which are divided into two (see FIG. 3).

  The electric motor unit A includes a stator 23 fixed to the first casing 22a, a rotor 24 disposed to face the stator 23 radially inward with a gap, and a rotor 24 disposed radially inward of the rotor 24. And a motor rotating shaft 25 that rotates integrally with the motor. The motor rotation shaft 25 can rotate at a high speed of about ten thousandths of a minute. The stator 23 is configured by winding a coil around a magnetic core, and the rotor 24 is configured by a permanent magnet or the like.

  One end (left side in FIG. 1) of the motor rotating shaft 25 in the axial direction is provided on the first casing 22a by the rolling bearing 40, and the other end (right side in FIG. 1) is provided on the first casing 22a by the rolling bearing 41. Each is rotatably supported.

  The reduction gear section B has an input gear 30, an input-side intermediate gear 31 and an output-side intermediate gear 32 as intermediate gears, and a final output gear 35. The input gear 30 is formed integrally with the input shaft 27, and the input shaft 27 is coaxially connected to the motor rotation shaft 25 by spline fitting (including serration fitting; the same applies hereinafter). The intermediate shaft 28 including the input-side intermediate gear 31 and the output-side intermediate gear 32 is formed integrally with the two intermediate gears 31 and 32. The output shaft 29 including the final output gear 35 is formed integrally with the final output gear 35. Any one or two or more of the gears 30, 31, 32, and 35 may be formed of a member separate from the corresponding shaft, and coupled to the shaft by spline fitting or the like.

  In the present embodiment, a helical gear is used as the input gear 30, the input intermediate gear 31, the output intermediate gear 32, and the final output gear 35 that constitute the parallel shaft gear mechanism 39. The helical gear is effective in that the number of teeth to be meshed at the same time increases and the tooth contact is dispersed, so that noise is quiet and torque fluctuation is small. It is preferable to set the number of modules of each gear to about 1 to 3 in consideration of the gear meshing ratio, the limit rotational speed, and the like.

  The gear shafts of the input shaft 27, the intermediate shaft 28, and the output shaft 29 are arranged parallel to each other. As shown in FIG. 2, the gear shafts 27, 28, and 29 are arranged so as to form a triangle when connecting their axis centers O1, O2, and O3 when viewed from the axial direction. Thus, by arranging the respective gear shafts 27, 28, 29 in a triangular shape so as not to be on the same straight line when viewed from the axial direction, the outer peripheral contour of the in-wheel motor drive device 21 is reduced in size. . Thus, the in-wheel motor drive device 21 can be mounted in the existing wheel 70.

  As shown in FIG. 1, rolling bearings 42 and 43 are disposed on both sides of the input gear 30 of the input shaft 27 in the axial direction, and the input shaft 27 is rotatable with respect to the casings 22a and 22b by the rolling bearings 42 and 43. It is supported by. The intermediate shaft 28 is rotated by the two rolling bearings 44 and 45 with respect to each of the casings 22a and 22b in a state where the input side intermediate gear 31 is arranged on the inboard side and the output side intermediate gear 32 is arranged on the outboard side. It is freely supported. Further, rolling bearings 46 and 47 are arranged on both axial sides of the final output gear 35 of the output shaft 29, and the output shaft 29 is rotatably supported by the rolling bearings 46 and 47 with respect to the casings 22a and 22b. .

  In the rolling bearings 44 and 45 that support the inboard side and the outboard side of the intermediate shaft 28, the rolling bearing 44 on the input side intermediate gear 31 side, which is the inboard side, has a larger diameter than the other rolling bearing 45. is there. That is, the inner diameter of the inboard-side rolling bearing 44 is larger than the inner diameter of the outboard-side rolling bearing 45, and the outer diameter of the inboard-side rolling bearing 44 is also the outer diameter of the outboard-side rolling bearing 45. Larger than dimensions. Further, the rolling bearing 44 that supports the inboard side of the intermediate shaft 28 is disposed in the inner diameter side recess 33 provided in the input side intermediate gear 31.

  In the rolling bearings 46 and 47 for supporting the inboard side and the outboard side of the output shaft 29, the rolling bearing 47 on the outboard side is opposite to the rolling bearings 44 and 45 for supporting the intermediate shaft 28. , Has a larger diameter than the other rolling bearing 46. That is, the inner diameter of the outboard-side rolling bearing 47 is larger than the inner diameter of the inboard-side rolling bearing 46, and the outer diameter of the outboard-side rolling bearing 47 is also the outer diameter of the inboard-side rolling bearing 46. Larger than dimensions. In addition, the rolling bearing 47 that supports the outboard side of the output shaft 29 is disposed in the inner diameter side concave portion 34 provided in the final output gear 35. As each of the rolling bearings 40 to 47 described above, a bearing capable of receiving both a radial load and a thrust load, for example, a deep groove ball bearing is used.

  The wheel bearing portion C includes an inner ring rotation type wheel bearing 50. The wheel bearing 50 is a double-row angular ball bearing mainly including an inner member 61 including a hub wheel 60 and an inner ring 52, an outer ring 53, a plurality of balls 56, and a retainer (not shown).

  The hub wheel 60 has a spline portion on the inner periphery, and is connected to the output shaft 29 via this spline portion so that torque can be transmitted. A flange portion 60a for mounting a wheel is formed on the outer periphery of the hub wheel 60 on the outboard side. Although not shown, a brake disk and a wheel are mounted on the wheel mounting flange portion 60a. On the other hand, the inner ring 52 is fitted to the small-diameter stepped portion on the inboard side of the hub wheel 60, and the caulked portion 60 b of the hub wheel 60 is pressed against the inner ring 52. The caulked portion 60b is formed by caulking the inboard end of the hub wheel 60 after the inner ring 52 is fitted to the hub wheel 60. The formation of the caulked portion 60b positions the inner ring 52 in the axial direction and applies a preload to the wheel bearing 50.

  An outer raceway surface 54 on the outboard side is formed on the outer periphery of the hub wheel 60, and an inner raceway surface 54 on the inboard side is formed on the outer periphery of the inner race 52. On the other hand, double rows of outer raceways 55 are formed on the inner periphery of the outer race 53 so as to correspond to the inner raceway 54 of the hub wheel 60 and the inner raceway 54 of the inner race 52. Balls 56 are arranged to be rollable between the inner raceway surface 54 and the outer raceway surface 55 facing each other.

  A flange portion is formed on the outer periphery of the outer ring 53, and the flange portion is fastened and fixed to the second casing 22 b via an attachment 72 with a bolt 71.

  As shown in FIG. 1, in the reduction gear section B, the input gear 30 and the input-side intermediate gear 31 mesh with each other, and the output-side intermediate gear 32 and the final output gear 35 mesh with each other. The number of teeth of the input side intermediate gear 31 is greater than the number of teeth of the input gear 30 (the input side intermediate gear 31 has a larger diameter than the input gear 30), and the number of teeth of the output side intermediate gear 32 is greater than the number of teeth of the final output gear 35. Less (the output side intermediate gear 32 has a smaller diameter than the final output gear 35). Therefore, when the input shaft 27 rotates due to the rotation of the motor rotation shaft 25, the rotation between the input gear 30 and the input intermediate gear 31 that mesh with each other is reduced, and further, the output intermediate gear 32 and the final output gear 32 that mesh with each other. The rotation is also reduced between 35. As described above, the speed reducer B constitutes the parallel shaft gear mechanism 39 that reduces the rotational movement of the motor rotation shaft 25 in two stages. As a result, the rotational torque of the electric motor 26 is amplified and transmitted to the rear wheel 14.

  Since the in-wheel motor drive device 21 is housed inside the wheel housing 15 (see FIG. 11) and is subjected to unsprung load, it is necessary to reduce the size and weight. By combining the parallel shaft gear mechanism 39 having the above-described configuration with the electric motor 26, it is possible to use a small electric motor 26 with low torque and high rotation. For example, when the parallel shaft gear mechanism 39 having a reduction ratio of 11 is used, the size of the electric motor 26 can be reduced by using the electric motor 26 that rotates at a high speed of about 10,000 thousands per minute. As a result, a compact in-wheel motor drive device 21 can be realized, and the electric vehicle 11 having excellent running stability and NVH characteristics by suppressing unsprung weight can be obtained.

  In the present embodiment, when assembling the above-described parallel shaft gear mechanism 39, the input shaft 27, the intermediate shaft 28, and the output shaft 29 are provided with respective rolling bearings 42 to 47 on their outer peripheral surfaces in advance to prevent creep. It is press-fitted and assembled in each of the casings 22a and 22b in an assembly state in which the respective gears mesh with each other (see FIG. 3).

  After the casings 22a and 22b are positioned with each other by a pair of knock pins 80, they are fastened and fixed by a plurality of bolts (not shown). Generally, it is preferable that the knock pins 80 be arranged as far as possible from each other in order to improve the positioning accuracy. In the present embodiment, as shown in FIG. 2, the casings 22 a and 22 b are formed in a non-circular cross-sectional shape, and the pair of knock pins 80 are constituted by the input shaft 27, the intermediate shaft 28, and the output shaft 29. They are arranged on opposite sides of the parallel shaft gear mechanism 39. In FIG. 2, a hole 91 formed with a smaller diameter than the hole 90 into which the knock pin 80 is inserted is a bolt hole for inserting a bolt for fastening the casings 22a and 22b to each other.

  Each knock pin 80 is tightly fitted to a hole 90 provided in one of the first casing 22a and the second casing 22b in consideration of the assembling property and disassembly, and is fitted to a hole 90 provided in the other. On the other hand, it is configured to be fitted with a gap. In the present embodiment, each knock pin 80 is tightly fitted to the hole 90 of the first casing 22a on the inboard side, and is clearance-fitted to the hole 90 of the second casing 22b on the outboard side. However, on the contrary, it is also possible to tightly fit the hole 90 of the second casing 22b on the outboard side and fit the gap 90 with the hole 90 of the first casing 22a on the inboard side. Good.

  By the way, since the knock pin 80 is clearance-fitted into the hole 90 of one of the casings, the fitting position of the casings 22a and 22b may change by the clearance of the hole 90 at the time of assembly. . The displacement between the casings 22a and 22b due to the gap fitting is very small, about several μm to several tens μm, but the input shaft 27 and the intermediate shaft are associated with the displacement between the casings 22a and 22b. 28, when the center positions of the rolling bearings 42, 44, 46 on the first casing 22a side supporting the respective gear shafts of the output shaft 29 and the rolling bearings 43, 45, 47 on the second casing 22b side deviate. A relative inclination between the two, that is, a so-called misalignment occurs. When such misalignment of the gear shafts occurs, a transmission error of meshing between the gears occurs, which causes vibration and noise.

  Therefore, in the in-wheel motor drive device 21 according to the present embodiment, the arrangement of the knock pins 80 is set as follows in order to reduce misalignment that can occur on the gear shaft.

  FIG. 4 is a cross-sectional view showing the arrangement of the knock pins.

  In FIG. 4, the hole 90 is relatively displaced from the position shown by the two-dot chain line to the position shown by the solid line with respect to the knock pin 80, so that the shaft centers of the gear shafts 27, 28, and 29 are shifted from their normal positions. This shows a shifted state. In this case, it is assumed that each hole 90 is displaced clockwise in FIG. 4 by an angle θ. Accordingly, the respective gear shafts 27, 28, 29 are displaced clockwise about the midpoint M of the line segment connecting the centers of the pair of knock pins 80. In FIG. 4, O1, O2, and O3 denote the normal shaft centers of the gear shafts 27, 28, and 29 without any displacement, and O1 ', O2', and O3 'denote the respective gear shafts 27, 28, and 29. It shows the axis center when a displacement occurs. In addition, the diameter of the hole part 90 and the amount of positional deviation are exaggerated for easy understanding.

  The positioning accuracy is improved when the pair of knock pins 80 are arranged apart from each other. That is, as shown in FIG. 5, since the positional shift amount δ for the clearance of the hole 90 is determined to some extent, the distance from the center of the positional shift (middle point M) between the knock pins 80 to the center of the knock pin 80 is reduced. The longer one (in the case of the distance N1) has a smaller displacement angle than the shorter one (in the case of the distance N2) (angle θ1 <angle θ2).

  From this point of view, in the example shown in FIG. 4, the line segment connecting the centers of the pair of knock pins 80 is a triangle formed by connecting the normal shaft centers O1, O2, O3 of the respective gear shafts 27, 28, 29. Each knock pin 80 is arranged so as to pass through two vertices (in this case, axial centers O1 and O3). In addition, an intermediate point M of a line connecting the centers of the pair of knock pins 80 is on a side of a triangle formed by connecting the normal shaft centers O1, O2, O3 of the respective gear shafts 27, 28, 29 (in this case, (Between two axis centers O1 and O3).

  Generally, the gear shaft constituting the reduction gear tends to be arranged at the center of the casing and in the vicinity thereof (see FIG. 2). Therefore, as in the present embodiment, a line segment connecting the centers of the pair of knock pins 80 passes through two vertices of a triangle connecting the axial centers O1, O2, and O3 of the gear shafts 27, 28, and 29. By doing so, the knock pins 80 are arranged at two relatively distant points on the casing. As a result, the positioning accuracy of the knock pin 80 is improved, so that misalignment in each of the gear shafts 27, 28, 29 can be reduced.

  Further, from the same viewpoint, the knock pin 80 may be arranged as in each example shown in FIGS. In the example shown in FIG. 6, a line segment connecting the centers of the pair of knock pins 80 is one vertex of a triangle formed by connecting the normal shaft centers O1, O2, O3 of the respective gear shafts 27, 28, 29 (this In this case, each knock pin 80 is arranged so as to pass through the axis center O3) and the intersection P1 with one side. In the example shown in FIGS. 7 to 9, the line connecting the centers of the pair of knock pins 80 is a triangle 2 formed by connecting the normal shaft centers O1, O2, O3 of the respective gear shafts 27, 28, 29. Each knock pin 80 is arranged so as to pass through intersections P1 and P2 with the two sides. In each of the examples shown in FIGS. 6 to 9, an intermediate point M of a line connecting the centers of the pair of knock pins 80 connects the normal shaft centers O1, O2, and O3 of the gear shafts 27, 28, and 29. It is located inside the formed triangle.

  As described above, the line segment connecting the centers of the pair of knock pins 80 is any two of the vertices of the triangle connecting the shaft centers O1, O2, and O3 of the gear shafts 27, 28, and 29 and the intersection with each side. By passing the two, the pair of knock pins 80 can be arranged as far apart as possible, the positioning accuracy by the knock pins 80 can be improved, and the misalignment at each gear shaft 27, 28, 29 can be reduced. is there. Thereby, vibration and noise generated between the gear shafts can be suppressed. Further, by reducing the misalignment, the amount of gear tooth surface correction can be reduced, and the time and cost required for processing can be reduced.

  Further, as described above, when the respective gear shafts 27, 28, 29 are displaced in the rotational direction, the inventor of the present invention changes the amount of displacement of the respective gear shafts 27, 28, 29 in accordance with the arrangement of the knock pin 80. I focused on doing. That is, when each of the gear shafts 27, 28, 29 is displaced in the rotational direction, the amount of these displacements is calculated from the intermediate point M between the knock pins 80 serving as the center of rotation to the axial center O1, of each of the gear shafts 27, 28, 29. It is proportional to each distance R1, R2, R3 to O2, O3. Therefore, by adjusting the position of the knock pin 80, it is possible to set the relative magnitude relationship of misalignment that can occur in each of the gear shafts 27, 28, 29. Note that the gear shafts 27, 28, 29 may be displaced in the same direction as the vertical or horizontal direction in FIG. 4 instead of the rotational direction. Since the displacement amounts are the same, the arrangement of the knock pins 80 when the gear shafts 27, 28, 29 are displaced in the rotational direction will be described here.

  Generally, the relative magnitude relationship of misalignment that can occur in each of the gear shafts 27, 28, and 29 changes according to the amount of displacement between the casings, as well as the gear load, the gear shaft specifications (the rigidity of the gear shaft, It can also vary depending on the bearing dimensions supporting the gear shaft (bearing elastic deformation, bearing clearance, ball diameter, curvature of ball rolling surface, etc.), casing dimensions, and the like. However, it is possible to predict on which gear shaft the misalignment that changes due to the gear load, the gear shaft specifications, the bearing specifications, the casing dimensions, etc. can be large by analysis. Therefore, among the plurality of gear shafts, if there is one that is expected to have the largest misalignment, by adjusting the arrangement of the knock pin with respect to the gear shaft, the gear caused by the displacement between the casings is adjusted. It is possible to reduce the misalignment of the shaft as compared with the other gear shafts, and to reduce the total misalignment that can occur.

  For example, in the example shown in FIG. 4, the distances R1, R2, and R3 from the intermediate point M to the shaft centers O1, O2, and O3 of the gear shafts 27, 28, and 29 are the intermediate shaft 28, the input shaft 27, and the output. It is set so as to become gradually smaller in the order of the axis 29 (R2> R1> R3). Therefore, in this case, the displacement L1, L2, L3 of each gear shaft 27, 28, 29 due to the displacement between the casings gradually decreases in the order of the intermediate shaft 28, the input shaft 27, and the output shaft 29 (L2). > L1> L3).

  The arrangement of the knock pins 80 as in the example shown in FIG. 4 is suitable when the misalignment that can occur due to factors other than the displacement between the casings is expected to gradually increase in the order of the intermediate shaft 28, the input shaft 27, and the output shaft 29. It is suitable. That is, by arranging the knock pins 80 as shown in FIG. 4, the displacement amount caused by the displacement between the casings with respect to the output shaft 29 where misalignment is expected to be the largest by the pre-analysis is considered. Since L3 can be made smaller than the displacement amounts L1 and L2 of the other gear shafts 27 and 28 (L2> L1> L3), the total misalignment that can occur on the output shaft 29 can be reduced. Further, for the input shaft 27 for which misalignment due to the pre-analysis is expected to be the second largest, the displacement L1 due to the displacement between the casings is made smaller than the displacement L2 of the intermediate shaft 28. (L2> L1), the total misalignment that can occur on the input shaft 27 can be reduced.

  In this manner, the distances R1, R2, R3 from the midpoint M of the line segment connecting the centers of the knock pins 80 to the axis centers of the gear shafts 27, 28, 29 can be generated on the gear shafts 27, 28, 29. By setting based on the size of misalignment (excluding misalignment caused by displacement between casings), the misalignment of a specific gear shaft can be larger than the misalignment of other gear shafts. Can be suppressed. This makes it possible to suppress the occurrence of vibration and noise due to an increase in misalignment in some gear shafts.

  Also, as in other examples shown in FIGS. 6 to 9, the distances R1, R2, and R3 from the intermediate point M to the shaft centers O1, O2, and O3 of the gear shafts 27, 28, and 29 are changed. It is possible to change the relative magnitude relationship between the displacement amounts L1, L2, L3 caused by the displacement between the casings. Specifically, in FIG. 6, the magnitude relationship between the displacement L1 of the input shaft 27 and the displacement L2 of the intermediate shaft 28 is reversed from the example shown in FIG. In the example shown in FIG. 7, the magnitude relationship between the displacement L2 of the intermediate shaft 28 and the displacement L3 of the output shaft 29 is reversed from that in the example shown in FIG. Note that the magnitude relationship between the positional deviation amounts is not limited to the examples shown in FIGS. 4, 6, and 7, and may be appropriately changed based on the magnitude of misalignment that can occur in each of the gear shafts 27, 28, and 29. It is possible.

  Further, unlike the above-described respective examples, as shown in an example shown in FIG. The distances R2, R3 from the intermediate point M to the respective gear shafts 29 are the same, and the distances R1, R2, R3 from the intermediate point M to all the gear shafts 27, 28, 29 as in the example shown in FIG. Can be set to be the same.

  For example, when the misalignment that can be analyzed in advance is expected to be substantially the same between the input shaft 27 and the intermediate shaft 28 and the output shaft 29, the arrangement of the knock pins 80 is as shown in FIG. This makes it possible to reduce the amount of misalignment caused by the misalignment between the casings in the intermediate shaft 28 and the output shaft 29 as compared with the input shaft 27, while maintaining the same amount in the intermediate shaft 28 and the output shaft 29 ( L1> L2 = L3). As a result, the total misalignment that can occur between the intermediate shaft 28 and the output shaft 29 can be reduced. It should be noted that which of the three gear shafts 27, 28, 29 has the same value of the distance from the intermediate point M for any combination of the gear shafts can be appropriately changed by anticipated misalignment. Further, the distance from the intermediate point M set to the same value among the plurality of gear axes is not limited to the case where the distance from the intermediate point M to the other gear axes is small, but may be the case where it is large.

  If the misalignment that can be analyzed in advance is expected to be substantially the same for all the gear shafts 27, 28, and 29, the arrangement of the knock pins 80 may be as shown in FIG. In this case, the amount of misalignment due to misalignment between the casings can be made the same for all gear shafts 27, 28, 29 (L1 = L2 = L3). Variations in the total misalignment obtained can be eliminated and made uniform.

  As described above, the embodiments of the present invention have been described, but the present invention is not limited to the above-described embodiments, and it is needless to say that the present invention can be embodied in various forms without departing from the gist of the present invention. It is.

  In the above-described embodiment, the configuration in which the reduction gear section B has three gear shafts 27, 28, and 29 parallel to each other has been described as an example. However, in the present invention, four or more gear shafts are arranged parallel to each other. The present invention is also applicable to those having a reduction gear unit. Accordingly, a line segment connecting the centers of the knock pins 80 may be any one of intersections with vertexes and sides of a polygon such as a triangle, a quadrangle, or a pentagon formed by connecting the axis centers of three or more gear shafts. What is necessary is just to arrange so that it may pass through two. By doing so, the pair of knock pins 80 can be arranged as far as possible, so that the positioning accuracy of the knock pins 80 can be improved and the misalignment in each gear shaft can be reduced.

  Further, even in a configuration including a reduction gear unit in which four or more gear shafts are arranged in parallel with each other, the distance from the midpoint M of the line segment connecting the centers of the knock pins 80 to the shaft center of each gear shaft is By setting based on the magnitude of the misalignment of the gear shaft, it is possible to prevent the misalignment of some gear shafts from becoming particularly large, and to suppress the generation of vibration and noise.

  In the above-described embodiment, the gears (the input gear 30, the input-side intermediate gear 31, the output-side intermediate gear 32, and the final output gear 35) of each of the gear shafts 27, 28, and 29 are helical gears. However, the present invention is also applicable to a configuration including a spur gear shaft. Also in the case of spur gears, mesh transmission errors occur due to gear shaft misalignment, which causes vibration and noise.By applying the present invention, gear shaft misalignment is reduced, and vibration and noise are reduced. Can be suppressed.

Reference Signs List 21 in-wheel motor drive device 22a first casing 22b second casing 27 input shaft 28 intermediate shaft 29 output shaft 30 input gear 31 input-side intermediate gear 32 output-side intermediate gear 35 final output gear 39 parallel shaft gear mechanism 42 rolling bearing 43 rolling Bearing 44 Rolling bearing 45 Rolling bearing 46 Rolling bearing 47 Rolling bearing 80 Knock pin A Electric motor section B Reduction gear section C Wheel bearing section M Middle point of line segment connecting the centers of respective knock pins O1 Input shaft center O2 Middle shaft Shaft center O3 Shaft center of output shaft R1 Distance from midpoint of line segment connecting the centers of knock pins to axis center of input shaft R2 Distance from midpoint of line segment connecting centers of knock pins to center of axis of intermediate shaft R3 Distance from the midpoint of the line connecting the centers of the knock pins to the center of the output shaft

Claims (9)

An electric vehicle drive device including an electric motor unit, a wheel bearing unit, and a speed reducer unit that transmits torque from the electric motor unit to the wheel bearing unit.
The reduction gear unit includes a parallel shaft gear mechanism having three or more gear shafts arranged in parallel with each other, a first casing provided with a bearing that supports one end of the gear shaft, and a gear shaft. A second casing provided with a bearing for supporting an end portion, wherein the first casing and the second casing are positioned by a pair of knock pins,
When viewed from the axial direction, a line segment connecting the centers of the knock pins passes any two of the intersections with the vertices and sides of a polygon formed by connecting the axis centers of the gear shafts. An electric vehicle drive device, wherein the knock pins are arranged.   2. The knock pins are arranged such that a line connecting the centers of the knock pins passes through two vertices of a polygon formed by connecting the axis centers of the gear shafts when viewed from the axial direction. An electric vehicle drive device according to claim 1.   When viewed from the axial direction, the line segment connecting the centers of the knock pins passes through the intersection of one vertex and one side of a polygon formed by connecting the axis centers of the gear shafts. The electric vehicle drive device according to claim 1, wherein a knock pin is arranged.   When viewed from the axial direction, the knock pins are arranged such that a line connecting the centers of the knock pins passes through an intersection with two sides of a polygon formed by connecting the axis centers of the gear shafts. The electric vehicle drive device according to claim 1. An electric vehicle drive device including an electric motor unit, a wheel bearing unit, and a speed reducer unit that transmits torque from the electric motor unit to the wheel bearing unit.
The reduction gear unit includes a parallel shaft gear mechanism having three or more gear shafts arranged in parallel with each other, a first casing provided with a bearing that supports one end of the gear shaft, and a gear shaft. A second casing provided with a bearing for supporting an end portion, wherein the first casing and the second casing are positioned by a pair of knock pins,
When viewed from the axial direction, a distance from an intermediate point of a line segment connecting the centers of the knock pins to a shaft center of each gear shaft is set based on a magnitude of misalignment of each gear shaft. Electric vehicle drive device.   When viewed from the axial direction, the distance from the midpoint of the line connecting the centers of the knock pins to the shaft center of each gear shaft was set such that the distance to the gear shaft where misalignment was greatest was minimized. An electric vehicle drive device according to claim 5.   6. The distance according to claim 5, wherein a distance from an intermediate point of a line segment connecting the centers of the knock pins to a shaft center of each gear shaft is set to be the same distance in whole or in part when viewed from the axial direction. Electric vehicle drive. The parallel shaft gear mechanism includes an input shaft having an input gear into which torque from the electric motor unit is input, an output shaft connected to the wheel bearing unit and having an output gear, the input shaft and the output shaft. And one or more intermediate shafts that transmit power by meshing with gears between
8. The intermediate shaft according to claim 1, further comprising: an input-side intermediate gear having a larger diameter than the input gear and meshing with the input gear; and an output-side intermediate gear having a smaller diameter than the output gear and meshing with the output gear. 9. The electric vehicle drive device according to claim 1.   An in-wheel motor drive, wherein the electric vehicle drive according to any one of claims 1 to 8 is applied.

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