JP6374758B2 - In-wheel motor drive casing structure - Google Patents

Description

  The present invention relates to a casing that forms an outline of an in-wheel motor drive device.

  The in-wheel motor drive device is not only less burdensome on the environment because it is electrically driven, but also installed in the wheel of an automobile to drive the wheel, so that it has a larger cabin than an engine automobile. Space can be secured, which is advantageous. As an in-wheel motor drive device, conventionally, for example, a device described in JP 2011-111059 A (Patent Document 1) is known. An in-wheel motor drive device described in Patent Document 1 includes a casing that forms an outer shell of an in-wheel motor, and various components housed in the casing, specifically, a rotor of a motor unit, a curved plate of a reduction unit, and an inner plate. Including pins, etc.

JP 2011-111059 A

  The casing of the in-wheel motor drive device includes a plurality of casing members, and includes, for example, a cylindrical casing member and a disk-shaped casing member. The plurality of casing members are fixed to each other by bolts. Further, since the in-wheel motor drive device supports the vehicle weight, the vehicle weight acts on the casing. In particular, when the automobile turns and suddenly starts or decelerates, a large external force acts on the casing from the wheel side. If the casing rigidity is low, the casing deforms and the rotor of the motor section is damaged, the curvilinear plate and the inner pin of the speed reduction section are damaged, or the butting surfaces of the casing members are slightly opened to lubricate from inside the casing. Oil may ooze out. For this reason, it is necessary to increase the rigidity of the casing so that the casing does not deform.

  However, since the in-wheel motor drive device is attached to the vehicle body via a suspension member, it is included in a so-called unsprung load. For this reason, when the thickness of the casing is simply increased to increase the rigidity of the casing, a so-called unsprung load increases, which is not preferable in terms of running performance of the automobile.

  In view of the above circumstances, an object of the present invention is to provide a technique for improving the rigidity of a casing without increasing the thickness of the casing as much as possible.

  For this purpose, the casing structure of the in-wheel motor drive device according to the present invention is based on the premise of an in-wheel motor drive device including a motor part and a wheel hub bearing part driven by the motor part. The formed casing is threaded into each of the female screw holes while being passed through a first casing having a plurality of bolt seats, a second casing having a plurality of female screw holes, and a through hole formed in each of the plurality of bolt seats. And a plurality of bolts for connecting and fixing the first casing to the second casing. Then, one end opening of the through hole is formed, and a bolt seat surface that receives a pressing force from the head of the bolt is formed to protrude from the surface of the first casing. A rib extending to the bolt seat is formed.

  According to the present invention, since the rib extending from one bolt seat portion to another bolt seat portion is formed on the surface of the first casing, the rigidity of the first casing can be increased by the rib. Moreover, the pressing force acting on the bolt seat from the bolt head is transmitted so as to spread to the first casing via the rib, and the first casing can be firmly abutted and fixed to the second casing. Thereby, the sealing performance of the butting surfaces of the first casing and the second casing is improved. The surface of the first casing on which the rib is formed may be a flat surface as a whole, or may be a curved surface as a whole, or a part of the surface may be a relatively low flat surface. A part of the surface may be a relatively high flat surface, or may have an uneven shape, and is not particularly limited.

  The protrusion height of the rib protruding from the surface of the first casing is not particularly limited. As one embodiment of the present invention, the protruding edge of the rib protruding from the surface of the first casing extends linearly from the bolt seat surface of one bolt seat portion connected to the rib to the bolt seat surface of the other bolt seat portion. . According to such an embodiment, the protrusion height of the rib can be sufficiently secured, and the rigidity of the first casing can be sufficiently increased. As another embodiment of the present invention, the protruding height of the rib may be lower than the height from the casing surface to the bolt seat surface.

  The bolt seat portion and the female screw hole connected to each other may be formed in the vicinity of the butting surfaces of the first casing and the second casing, and the arrangement thereof is not particularly limited. As a preferred embodiment of the present invention, the bolt seat portion and the female screw hole are arranged at intervals in the circumferential direction of a casing formed in a cylindrical shape. According to this embodiment, the annular butting surface of the first casing and the annular butting surface of the second casing can be butted against each other and fixed firmly. As another embodiment of the present invention, the bolt seat portion and the female screw hole may be arranged along the butting surface extending in the axial direction of the casing.

  As a further preferred embodiment of the present invention, the female screw hole and the through hole of the bolt seat part extend in parallel to the axial direction of the casing formed in a cylindrical shape, and the rib projects in the axial direction from the surface of the first casing. According to this embodiment, the abutting surface of the first casing and the abutting surface of the second casing that are perpendicular to the axial direction of the casing can be abutted against each other in the axial direction and fixed tightly. When the butting surfaces are butted in the radial direction as another embodiment of the present invention, the female screw hole and the through hole may extend in the radial direction of the casing, and the rib may also protrude in the radial direction from the surface of the first casing.

  The shape of the first casing and the second casing is not particularly limited. As an embodiment of the present invention, the second casing has a cylindrical shape, the first casing has a disk shape, and the ribs are continuously connected in the circumferential direction so as to sequentially connect a plurality of bolt seats arranged in the circumferential direction. Be placed. According to this embodiment, when sealing the edge part of a cylindrical casing member with a disk-shaped casing member, both abutting surfaces can be stuck. As another embodiment of the present invention, both the first casing and the second casing may be cylindrical. The in-wheel motor drive device of the present invention preferably further includes a speed reducing portion that decelerates the output rotation of the motor portion and transmits it to the wheel hub bearing portion. The speed reducer may be a parallel twin shaft type or planetary gear type speed reducer. However, as a more preferred embodiment, the speed reducer receives rotation from the output shaft of the motor unit and is provided at different positions in the axial direction. An input shaft having a plurality of eccentric parts, a plurality of revolution members that are held by the eccentric parts so as to be relatively rotatable, and perform a revolving motion around the axis of the input shaft as the input shaft rotates, and An outer peripheral engagement member that engages with the outer periphery to cause the rotation of the revolving member, and a motion conversion mechanism that converts the rotation of the revolving member into a rotational movement around the axis of the input shaft and outputs it to the wheel hub bearing portion. And have. According to this embodiment, since the cycloid reducer is employed in the speed reducing portion, the weight can be reduced and a great speed reduction effect can be obtained.

  Thus, according to the present invention, the casing thickness can be increased and the rigidity of the casing can be improved without increasing the weight of the in-wheel motor drive device. Accordingly, it is possible to achieve both improvement of the rigidity of the casing and weight reduction of the in-wheel motor drive device, and the unsprung weight of the automobile is hardly increased, and the influence of the unsprung weight on traveling is reduced. Furthermore, the sealing performance of the butting surfaces of the first casing and the second casing is improved.

It is a longitudinal cross-sectional view which shows the in-wheel motor drive device which becomes one Embodiment of this invention. It is a cross-sectional view in II-II of FIG. It is a rear view which shows the embodiment typically. It is a longitudinal cross-sectional view in IV-IV of FIG. It is sectional drawing in VV of FIG. It is explanatory drawing which shows typically the compressive-stress distribution of the pressing force per volt | bolt of the same embodiment. It is explanatory drawing which shows typically the range to which the pressing force of all the volt | bolts acts in the butt | matching surface of the casing members of the embodiment. It is a rear view which shows typically the in-wheel motor drive device used as a comparative example. It is a longitudinal cross-sectional view in IX-IX of FIG. It is sectional drawing in XX of FIG. It is explanatory drawing which shows typically the compressive-stress distribution of the pressing force per volt | bolt of a comparative example. It is explanatory drawing which shows typically the range to which the pressing force of all the volt | bolts acts in the butt | matching surface of the casing members of a comparative example.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a longitudinal sectional view showing an in-wheel motor drive device according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing the embodiment. This embodiment is an in-wheel motor drive device that is disposed in an area inside a road wheel of a wheel. As shown in FIG. 1, the 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 outputs from the deceleration unit B to drive wheels. A wheel hub bearing C for transmission. The motor part A, the speed reduction part B, and the wheel hub bearing part C are arranged coaxially along the axis O of the in-wheel motor drive device in this order.

  The motor unit A includes a motor casing 22a, a pump casing 22p, and a motor rear cover 22t that form an outer shell of the motor unit. The speed reduction part B has a speed reduction part casing 22b that forms the outline of the speed reduction part. The motor rear cover 22t, the motor casing 22a, and the speed reduction unit casing 22b are coupled to each other by bolts and the like, and the pump casing 22p is integrally formed with the motor casing 22a to constitute one casing 22 as a whole. As described above, the casing 22 includes a plurality of casing members or casing portions. Then, the outer ring member 33 a of the wheel hub bearing portion C is attached and fixed to the casing 22. The in-wheel motor drive device 21 is disposed, for example, in a wheel housing of an electric vehicle and is attached to a suspension member (not shown). This electric vehicle is a passenger car, and can travel on public roads at high speed in the same manner as a general engine car.

  The motor part A includes a stator 23 fixed to the inner periphery of a cylindrical motor casing 22a, a rotor 24 disposed at a position facing the inner side of the stator 23 via a gap opened in the radial direction, and an inner side of the rotor 24. A radial gap motor including a motor rotating shaft 35 that is connected and fixed to the rotor 24 and rotates integrally with the rotor 24. Alternatively, although not shown, the motor part A may be an axial gap motor.

  The motor casing 22a extends about the axis O of the motor rotation shaft 35 in the axial direction. The pump casing 22p, which is a part of the casing 22, is a substantially disc-shaped partition wall, is integrally formed at one end of the motor casing 22a, and has a boundary with the speed reduction portion B at one end in the axis O direction of the motor portion A. While being formed, one end of the motor rotating shaft 35 is rotatably supported via the rolling bearing 37. Further, a suction oil passage 52, an oil pump 51, and a discharge oil passage 54 of the lubricating oil circuit are formed inside the wall thickness of the pump casing 22p. The lubricating oil circuit will be described later. The motor rear cover 22t, which is a part of the casing 22, has a substantially disk shape, is abutted against and fixed to the other end of the motor casing 22a, and forms the end surface of the motor unit A at the other end in the axis O direction of the motor unit A. At the same time, the other end of the motor rotating shaft 35 is rotatably supported via the rolling bearing 36. The motor rear cover 22t is an end portion of the motor portion A and also an end portion on the inner side in the vehicle width direction of the in-wheel motor drive device 21.

  One end of the motor rotating shaft 35 is coupled to a speed reducing portion input shaft 25 that is rotatably provided inside the speed reducing portion B. This coupling is spline fitting (including serration fitting; the same applies hereinafter), and the tapered speed reduction portion input shaft 25 is inserted into and engaged with the end opening of the motor rotation shaft 35 formed in a tubular shape. .

  The speed reduction part B is a cycloid speed reducer and is coaxially arranged on one side in the direction of the axis O of the motor part A, and has a cylindrical speed reduction part casing 22b and an outer pin attached and fixed to the inner peripheral surface of the speed reduction part casing 22b. A holding part 45, a speed reducing part input shaft 25 extending along the axis O, a pair of eccentric parts 25a, 25b formed on the speed reducing part input shaft 25, and the eccentric parts 25a, 25b are rotatably held. A pair of curved plates 26a and 26b as revolution members, a plurality of outer pins 27 as outer peripheral engaging members that engage with the outer peripheral portions of the curved plates 26a and 26b, and a speed reducing portion output shaft 28 extending along the axis O These are attached to the clearance between the pair of curved plates 26a and 26b, and a plurality of inner pins 31 as inner engagement members that are coupled to the speed reducing portion output shaft 28 and take out the rotation of the curved plates 26a and 26b. A linear plate 26a, a center collar 29 to prevent the inclination of the contact with the curved plate to the end surface of the 26b, and a reinforcing member 61 for fixing the ends of the plurality of inner pins 31.

  The speed reduction unit input shaft 25 extends along the axis O of the motor rotation shaft 35, and the end of the speed reduction unit input shaft 25 on the side closer to the motor unit A of both ends thereof is coupled to one end of the motor rotation shaft 35. . The end of the speed reduction part input shaft 25 on the side far from the motor part A is rotatably supported by the end of a speed reduction part output shaft 28 described later via a rolling bearing 39. A pair of eccentric portions 25 a and 25 b are formed eccentrically from the axis O on the outer periphery of the deceleration portion input shaft 25. The speed reducer input shaft 25 is rotatably supported by the reinforcing member 61 by the rolling bearing 38 on the side closer to the motor part A than the eccentric parts 25a and 25b.

  Each eccentric part 25a, 25b is a disk shape, and is eccentric from the axis O and is provided on the deceleration part input shaft 25. Further, the eccentric parts 25a and 25b form a pair of two and are arranged apart from each other in the direction of the axis O, and are provided with a phase difference of 180 ° in the circumferential direction so as to cancel out vibrations generated by the centrifugal force due to the eccentric movement. It has been. The motor rotation shaft 35 and the speed reduction part input shaft 25 constitute a motor side rotation member that transmits the driving force of the motor part A to the speed reduction part B, and rotate integrally.

  Referring to FIG. 2, curved plate 26b has a disc shape, and its outer peripheral portion is formed in a waveform. Specifically, the outer peripheral portion of the curved plate 26 b is a plurality of curved concave portions formed of a trochoidal curve such as an epitrochoid and recessed in the radial direction, and meshes with the outer pin 27. The curved plate 26b has a plurality of through holes 30a and 30b penetrating from one end face to the other end face. A plurality of through holes 30a are provided at equal intervals on the circumference centering on the rotation axis X of the curved plate 26b, and receive the inner pins 31. Moreover, the through-hole 30b is provided in the autorotation axis X of the curved plate 26b, and becomes an inner periphery of the curved plate 26b. The curved plate 26b is attached to the outer periphery of the eccentric portion 25b so as to be relatively rotatable. The inner pin 31 includes a needle roller bearing, and includes an inner pin main body 31a, a plurality of needle rollers 31b, and a bearing outer ring 31c. The inner pin main body 31a passes through the bearing outer ring 31c, and the needle rollers 31b are disposed in an annular space between the inner pin main body 31a and the bearing outer ring 31c. The outer peripheral surface of the bearing outer ring 31c is in rolling contact with the hole wall surface of the through hole 30a.

  The curved plate 26b is rotatably supported by the rolling bearing 41 with respect to the eccentric portion 25b. In order to facilitate understanding, a part of the rolling bearing 41 in the circumferential direction is shown in FIG. The rolling bearing 41 includes a plurality of rollers 44 disposed between an annular inner ring member 42 having an inner raceway surface 42a on the outer diameter surface and a hole wall surface of the through-hole 30b serving as the outer raceway surface. And a cylindrical roller bearing provided with a cage (not shown) that holds the interval between the rollers 44 adjacent in the circumferential direction. Alternatively, it may be a deep groove ball bearing. The inner diameter surface of the inner ring member 42 is fitted to the outer diameter surface of the eccentric portion 25b. The inner ring member 42 further includes a hole 43 that is located on the inner raceway surface 42a and penetrates in the radial direction and a pair of flanges that face each other across the inner raceway surface 42a. The hole 43 connects the inside of the eccentric portion 25b to a branch oil passage 58b extending in the direction perpendicular to the axis O. The same applies to the curved plate 26a.

  A plurality of outer pins 27 shown in FIG. 1 are provided at equal intervals on a circumferential track centering on the axis O of the motor side rotating member (see FIG. 2), and extend parallel to the axis O. When the two pair of curved plates 26a, 26b revolve around the axis O, the curved concave portions on the outer periphery of the curved plates 26a, 26b engage with the outer pin 27, and the curved plates 26a, 26b rotate. Give rise to

  The outer pin 27 disposed inside the speed reduction unit casing 22b may be directly connected and fixed to the inner wall surface of the speed reduction unit casing 22b, but is preferably attached and fixed to the inner wall surface of the speed reduction unit casing 22b. It is held by the outer pin holding part 45. More specifically, as shown in FIG. 1, both axial ends of the outer pin 27 are rotatably supported by needle roller bearings 27 a (rolling bearings) attached to the outer pin holding portion 45. In this way, by attaching the outer pin 27 to the outer pin holding portion 45 via the rolling bearing so as to be rotatable and rotatable, the contact resistance due to the engagement with the curved plates 26a and 26b can be reduced.

  As shown in FIG. 1, the speed reduction part output shaft 28 has a large-diameter flange part 28b at the end part on the motor part A side and a shaft part 28d on the wheel hub bearing part C side. A small-diameter flange portion 28c is formed at a connection portion between the large-diameter flange portion 28b and the shaft portion 28d. At the center of the large-diameter flange portion 28b, a circular concave portion 34 that receives one end of the speed reduction portion input shaft 25 is formed, and a rolling bearing 39 is disposed in the circular concave portion 34.

  The large-diameter flange portion 28b is formed with a hole for fixing one end portion of the inner pin 31 at equal intervals on the circumference centering on the axis O of the reduction portion output shaft 28. The wheel hub 32 of the wheel hub bearing portion C is connected and fixed to the outer peripheral surface of the shaft portion 28d.

  As shown in FIG. 1, a reinforcing member 61 is provided at the other end of the inner pin 31 on the side away from the large diameter flange portion 28b. The reinforcing member 61 is a flange-shaped large-diameter disc portion 61b that is coupled and fixed to the tips of the plurality of inner pins 31 inside the speed reduction portion B, and is coaxially formed adjacent to the large-diameter disc portion 61b. A small-diameter disk part 61c having a smaller diameter than the part 61b and a smaller-diameter cylindrical part 61d extending from the inner peripheral edge of the small-diameter disk part 61c to the motor part A are included. The large-diameter disc portion 61b is centered on the axis O, the small-diameter disc portion 61c is disposed closer to the motor portion A than the large-diameter disc portion 61b, and the cylindrical portion 61d is directed from the small-diameter disc portion 61c toward the motor portion A. Extending along the axis O.

  The load applied to a part of the inner pins 31 from the two curved plates 26a, 26b is all of the inner diameter via the large-diameter disk portion 61b of the reinforcing member 61 and the large-diameter flange portion 28b of the reduction portion output shaft 28. Since it is supported by the pins 31, the stress acting on each inner pin 31 can be reduced and the durability can be improved. The tip of the cylindrical portion 61d is inserted into the oil pump 51 to drive the oil pump 51 (see FIG. 1). A rolling bearing 38 is attached to the inner peripheral surface of the small-diameter disk portion 61c, and the rolling bearing 38 supports the speed reduction portion input shaft 25 rotatably.

  Since the reinforcing member 61 is connected to the speed reducing unit output shaft 28 via the inner pin 31, the reinforcing member 61 rotates integrally with the speed reducing unit output shaft 28. As shown in FIG. 1, the speed reducer output shaft 28, the reinforcing member 61, and the wheel hub 32 are wheel-side rotating members that transmit the driving force of the speed reducer B to drive wheels (drive wheels (not shown) connected to the bolts 32 c). Configure.

  Roller bearings 62 and 64 are disposed at both ends of the outer pin holding portion 45. The rolling bearings 62 and 64 rotatably support the wheel side rotating member. Specifically, the rolling bearing 62 is fitted to the outer diameter of the large-diameter disk portion 61 b of the reinforcing member 61, and the rolling bearing 64 is fitted to the outer diameter of the large-diameter flange portion 28 b of the reduction unit output shaft 28. Then, the speed reducing portion output shaft 28 and the reinforcing member 61 are rotatably supported by the outer pin holding portion 45. The rolling bearing 62 is disposed on the side close to the motor part A, and the rolling bearing 64 is disposed on the side close to the wheel hub bearing part C.

  The oil pump 51 is connected to a suction oil passage 52 and a discharge oil passage 54 provided inside the wall thickness of the pump casing 22p, and is lubricated with oil from an oil tank 53 provided in a lower portion of the speed reduction unit B via the suction oil passage 52. And high pressure lubricating oil is discharged from the discharge oil passage 54. The discharge oil passage 54 is provided in the wall thickness of the motor casing 22a and extends in the axial direction, the oil passage 56 provided in the wall thickness of the motor rear cover 22t and extends in the radial direction, and a tubular motor rotation. An axial oil passage 57 provided inside the shaft 35 and the speed reduction portion input shaft 25 and extending along the axis O, and a branch oil passage 58a and an eccentric portion 25b extending radially outward from the axis O in the eccentric portion 25a. Are sequentially connected to a branch oil passage 58b extending in the same manner and a hole 43 (see FIG. 2) formed in the inner ring member 42 fitted to the outer periphery of each of the eccentric portions 25a and 25b. Further, an opening 58 c connected to the circular recess 34 is provided at the tip of the axial oil passage 57.

  The lubricating oil discharged from the oil pump 51 flows through these oil passages 54, 55, 56, 57, 58 a (58 b), the opening 58 c, and the hole 43 in order, and the inside of the speed reduction part B (rolling bearings 38, 39, 41). , 62, 64, curved plates 26a, 26b, inner pin 31, outer pin 27, etc.) are lubricated and cooled. The lubricating oil after lubrication falls and collects in the oil tank 53. Then, it is sucked again by the oil pump 51 and circulates inside the in-wheel motor drive device 21. As described above, the in-wheel motor drive device 21 according to the present embodiment includes an axial center-lubricated lubricating oil circuit and injects lubricating oil from the speed reduction unit input shaft 25. Then, the lubricating oil flows radially outward from the speed reducer input shaft 25 to lubricate and cool the speed reducer B.

  The lubricating oil branches off from the axial oil passage 57 and flows through a rotor oil passage 59 formed in the rotor 24 to cool the inside of the motor part A and lubricate the rolling bearings 36 and 37. The lubricated lubricating oil falls in the internal space L of the motor part A and collects in the oil tank 53.

  The wheel hub bearing portion C is a rolling bearing having an inner ring 33c, a wheel hub 32 as a rotating shaft, a rolling element 33, and an outer ring member 33a as shown in FIG. The wheel hub 32 is coaxially arranged on one side of the speed reduction unit output shaft 28 in the axis O direction, and is connected and fixed to the speed reduction unit output shaft 28. The outer ring member 33 a is fixed to one end of the speed reduction unit casing 22 b with a bolt 33 b, and the inner ring 33 c is fitted and fixed to the outer peripheral surface of the wheel hub 32. The wheel hub bearing portion C is a double-row angular contact ball bearing having a large number of rolling elements 33 in two rows, and is arranged between the outer ring member 33a and the inner ring 33c on the side where the rolling elements 33 in the first row are close to the speed reduction portion B. The second row of rolling elements 33 is disposed between the outer ring member 33 a and the wheel hub 32 on the side far from the speed reduction portion B.

  The wheel hub 32 includes a cylindrical hollow portion 32a and a wheel mounting flange portion 32b that protrudes from one end of the hollow portion 32a in the outer diameter direction. The shaft portion 28d is spline-fitted (including serration fitting; the same applies hereinafter) to the central hole of the hollow portion 32a. An inner raceway surface that is in rolling contact with the second row of rolling elements 33 is directly formed on the outer peripheral surface of the hollow portion 32a. A drive wheel road wheel (not shown) is connected and fixed to the wheel mounting flange portion 32b by a bolt 32c.

  With reference to FIG. 1 and FIG. 2, the operation principle of the in-wheel motor drive device 21 having the above configuration will be described in detail.

  In the motor part A, for example, by supplying an alternating current to the coil of the stator 23, the rotor 24 composed of a permanent magnet or a magnetic material rotates. Thereby, when the motor rotating shaft 35 connected to the rotor 24 rotates, the curved plates 26a and 26b revolve around the axis O of the motor side rotating member. At this time, the outer pin 27 is engaged with the curved concave portions formed on the outer circumferences of the curved plates 26a and 26b while rolling, and rotates the curved plates 26a and 26b in the direction opposite to the rotation of the motor side rotating member. Exercise.

  The inner pin 31 inserted through each through hole 30a is sufficiently thinner than the inner diameter of the through hole 30a, and abuts against the hole wall surface of the through hole 30a as the curved plates 26a and 26b rotate (see FIG. 2). As a result, the revolving motion of the curved plates 26a and 26b is not transmitted to the inner pin 31, but only the rotational motion of the curved plates 26a and 26b is transmitted to the wheel hub bearing portion C via the speed reduction portion output shaft 28. The bearing outer ring 31c of the inner pin 31 rolls along the hole wall surface of the through hole 30a. At this time, a part of the bearing outer ring 31c is in contact with the hole wall surface of the through hole 30a, and the remaining part of the bearing outer ring 31c is not in contact with the hole wall surface of the through hole 30a. The bearing outer ring 31c is in rolling contact with the hole wall surface of the through hole 30a while repeating a contact state and a non-contact state.

  At this time, the speed reduction part output shaft 28 arranged coaxially with the axis O takes out the rotation of the curved plates 26 a and 26 b as the output axis of the speed reduction part B. As a result, the rotation of the speed reduction unit input shaft 25 is decelerated by the speed reduction unit B and transmitted to the speed reduction unit output shaft 28. Therefore, even when the low torque, high rotation type motor unit A is employed, it is necessary for the drive wheels. Torque can be transmitted. In this case, the through hole 30 a, the inner pin 31, and the speed reducer output shaft 28 convert the rotational motion of the curved plates 26 a and 26 b into rotational motion about the axis O of the speed reducer input shaft 25. A motion conversion mechanism that outputs to the wheel hub bearing portion C is configured.

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

  Next, the casing 22 will be described in more detail.

  The upper part of the speed reduction part casing 22b is rotatably connected to an upper arm of a suspension device (not shown). The lower part of the speed reduction part casing 22b is connected to a lower arm of a suspension device (not shown). Thereby, the deceleration part casing 22b (in-wheel motor drive device 21) is supported by the vehicle body of a motor vehicle. The vehicle weight is transmitted to the road surface via the suspension device, the speed reduction portion casing 22b, the wheel hub bearing portion C, and the wheels.

  As shown in FIG. 1, a bolt seat 22 s and a rib 22 r are integrally formed on the motor rear cover 22 t of the casing 22. A female screw hole 76 is formed in the motor casing 22a. A through hole 22v is formed through each bolt seat 22s. Each through hole 22v is connected to the female screw hole 76, respectively. Specifically, each female screw hole 76 and each through-hole 22v extend continuously in parallel with the axis O of the casing 22 formed in a cylindrical shape. One end opening of the through hole 22v is formed in the bolt seat surface 22w of the bolt seat portion 22s. The other end opening of the through hole 22v is formed in the butting surface 22m.

  Bolts 71 are passed through the through holes 22v from the outside of the casing 22. The male screw portion 72 of the bolt 71 is screwed into the female screw hole 76. The head 73 of the bolt 71 presses the bolt seat surface 22w of the bolt seat 22s. Of course, a washer 74 may be interposed between the head 73 and the bolt seat surface 22w. The washer 74 is in contact with the lower neck surface of the head 73 and the bolt seat surface 22w. By firmly tightening the plurality of bolts 71, the motor rear cover 22t is connected and fixed to the motor casing 22a.

  FIG. 3 is a rear view showing the in-wheel motor drive device 21 as seen from the inner side in the vehicle width direction, and shows the overall arrangement of the ribs 22r. FIG. 4 schematically shows a state in which the casing 22 (motor casing 22a, speed reducer casing 22b, pump casing 22p, motor rear cover 22t) and outer ring member 33a are taken out, cut along IV-IV in FIG. 3, and viewed in the direction of the arrow. It is a longitudinal cross-sectional view shown, and represents the cross-sectional shape of the rib 22r. FIG. 5 is a cross-sectional view schematically showing a state in which the casing 22 and the outer ring member 33a are cut along VV in FIG. 3 and viewed in the direction of the arrow, and represents a vertical cross section of the rib 22r.

  As schematically shown in FIG. 3, a plurality of bolt seat portions 22 s are arranged at intervals in the circumferential direction of the casing 22. Similarly, each female screw hole 76 (see FIG. 1) is also arranged at a position corresponding to each bolt seat 22s. The rib 22r is disposed between the adjacent bolt seat portions 22s and 22s, and extends from one bolt seat portion 22s to the other bolt seat portion 22s. Further, the rib 22r extends continuously in the circumferential direction so as to sequentially connect the plurality of bolt seats 22s, 22s, 22s,..., And extends around the motor rear cover 22t.

As shown in FIGS. 1 and 5, the bolt seat surface 22w is formed to protrude from the casing surface 22x of the motor rear cover 22t. The casing surface 22x is a plane perpendicular to the axis O. The rib 22r protrudes from the casing surface 22x in the direction of the axis O. As shown in FIG. 5, the protruding edge 77 of the rib 22r protruding from the casing surface 22x extends linearly from one bolt seat surface 22w to the other bolt seat surface 22w. The butting surface 22m of the motor rear cover 22t is a plane perpendicular to the axis O. Total projected height of a predetermined thickness from the abutment surface 22m until the casing surface 22x and ribs 22r, i.e. the distance to the abutment surface 22m of the bolt bearing surface 22w and _{h v.} Note _{h v} is also a full length of the through hole 22v.

  FIG. 6 schematically shows the stress distribution that the pressing force exerts on the bolt seat 22s and the rib 22r when the bolt head 73 presses the bolt seat 22w. The distribution of this compressive stress spreads from the outer edge of the head 73 in the pressing direction indicated by a thick arrow in FIG. The extent of this spread becomes wider as the distance from the head 73 increases, as conceptually shown in FIG. 6 by angle α and dot-like hatching.

  By the way, according to the present embodiment, the casing 22 that forms the outline of the in-wheel motor drive device 21 includes a motor rear cover 22t having a plurality of bolt seat portions 22s, a motor casing 22a having a plurality of female screw holes 76, and a plurality of bolts. It includes a plurality of bolts 71 for connecting and fixing the motor rear cover 22t to the motor casing 22a by being screwed into each of the female screw holes 76 while being passed through the through holes 22v respectively formed in the seat portion 22s. And the bolt seat surface 22w in which one end opening of the through-hole 22v is formed protrudes from the casing surface 22x of the motor rear cover 22t. Furthermore, a rib 22r extending from one bolt seat 22s to another bolt seat 22s is formed on the casing surface 22x. As a result, the rigidity of the motor rear cover 22t can be improved without increasing the thickness of the motor rear cover 22t, and the pressing force applied from the bolt 71 to the bolt seat surface 22w can be abutted between the motor rear cover 22t and the motor casing 22a. It can affect the surface 22m widely. As a result, the motor rear cover 22t and the motor casing 22a are brought into close contact with each other at the abutting surface 22m, and the sealing performance of the abutting surface 22m is improved.

  Further, according to the present embodiment, as shown in FIG. 5, the protruding edge 77 of the rib 22r protruding from the casing surface 22x is from the bolt seat surface 22w of one bolt seat 22s connected to the rib 22r to the other bolt seat. Since it extends linearly to the bolt seat surface 22w of 22s, the rigidity of the motor rear cover 22t can be sufficiently increased.

  Further, according to the present embodiment, as shown in FIG. 3, the bolt seat portion 22 s is arranged with a female screw hole 76 not shown in FIG. 3 at intervals in the circumferential direction of the casing 22 formed in a cylindrical shape. The annular abutting surface 22m of the motor rear cover 22t and the annular abutting surface 22m of the motor casing 22a can be abutted against each other and fixed firmly.

  Further, according to the present embodiment, as shown in FIG. 1, the female screw hole 76 and the through hole 22v of the bolt seat portion 22s extend in parallel with the axis O of the casing 22 formed in a cylindrical shape. The rib 22r protrudes in the axial direction from the casing surface 22x of the motor rear cover 22t. As a result, the butting surface 22m of the motor rear cover 22t and the butting surface 22m of the motor casing 22a perpendicular to the axis O can be butted against each other and fixed firmly.

  FIG. 7 is an explanatory diagram schematically showing hatching in a range where the pressing force of all the bolts 71 acts on the abutting surface 22m between the casing members of the present embodiment. As shown by dot-shaped hatching in FIG. 7, it can be seen that the pressing force of the bolt 71 extends over the entire circumference of the abutting surface 22 m without interruption at the center of the rib 22 r.

  In order to facilitate understanding of the present invention, a comparative example will be described. FIG. 8 is a rear view schematically showing an in-wheel motor drive device as a comparative example, and shows a state in which the motor rear cover 22t is viewed from the inner side in the vehicle width direction. FIG. 9 is a longitudinal sectional view taken along the line IX-IX in FIG. 8 and shows the casing 22 taken out. FIG. 10 is a cross section taken along line XX in FIG. 8 and represents between adjacent bolt seats. FIG. 11 is an explanatory diagram schematically showing the compressive stress distribution of the pressing force per bolt of the comparative example. FIG. 12 is an explanatory diagram schematically showing a range in which the pressing force of all bolts acts on the abutting surfaces of the casing members of the comparative example.

In the comparative example, the rib 22r is not provided. Further, the bolt seat portion 22s is not formed so as to protrude from the casing surface 22x. For this reason, the total length of the bolt 71 is also short. Note the width W _H of the head 73, as shown in FIGS. 6 and 11, common to comparative examples and embodiments described above. Since the other points are the same as in this embodiment, common parts are denoted by the same reference numerals and description thereof is omitted.

In the comparative example, as shown in FIG. 10, the dimension h _c from the casing surface 22x of the motor rear cover 22t to the butting surface 22m is the length of the bolt seat portion 22s and the through hole 22v (h _c <h _v ).

As shown in FIG. 11, the spreading range W _c where the pressing force of the bolt head 73 of the comparative example reaches the abutting surface 22 m becomes smaller in proportion to the dimension h _c (W _c <W _v ).

  As a result, the range in which the pressing force of all the bolts 71 acts on the abutting surfaces 22m of the casing members of the comparative example is discontinuous between the adjacent bolt seat portions 22s as shown by dot-shaped hatching in FIG. You can see that

  Although the embodiments of the present invention have been described with reference to the drawings, the present invention is not limited to the illustrated embodiments. Various modifications and variations can be made to the illustrated embodiment within the same range or equivalent range as the present invention.

  The in-wheel motor drive device according to the present invention is advantageously used in electric vehicles and hybrid vehicles.

21 in-wheel motor drive device, 22 casing,
22a motor casing, 22b reduction gear casing,
22m butt surface, 22p pump casing,
22r rib, 22s bolt seat, 22t motor rear cover,
22v through hole, 22w bolt seat surface, 22x casing surface,
28 Speed reducer output shaft, 31 inner pin, 32 wheel hub,
35 Motor rotation shaft, 51 Oil pump, 53 Oil tank,
71 bolts, 72 male threaded parts, 73 heads,
74 washers, 76 female screw holes, 77 protruding edges,
A motor part, B reduction part, C wheel hub bearing part,
O axis, X axis of rotation.

Claims (6)

In an in-wheel motor drive device comprising a motor part and a wheel hub bearing part driven by the motor part,
The casing that forms the outline of the in-wheel motor drive device includes a first casing having a plurality of bolt seats, a second casing having a plurality of female screw holes, and through holes formed in the plurality of bolt seats, respectively. A plurality of bolts for connecting and fixing the first casing to the second casing by screwing into each of the female screw holes while being passed,
One end opening of the through hole is formed and a bolt seat surface that receives a pressing force from the head of the bolt is formed to protrude from the surface of the first casing,
A casing structure of an in-wheel motor drive device, wherein a rib extending from one bolt seat portion to another bolt seat portion is formed on a surface of the first casing.   The protruding edge of the rib protruding from the surface of the first casing extends linearly from the bolt seat surface of one of the bolt seat portions connected to the rib to the bolt seat surface of the other bolt seat portion. The casing structure of the in-wheel motor drive device according to claim 1.   The casing structure of the in-wheel motor drive device according to claim 1, wherein the bolt seat portion and the female screw hole are arranged at intervals in a circumferential direction of the casing formed in a cylindrical shape. The female screw hole and the through hole of the bolt seat portion extend in parallel with the axial direction of the casing formed in a cylindrical shape,
The casing structure of the in-wheel motor drive device according to claim 3, wherein the rib protrudes from the surface of the first casing in the axial direction.   The second casing has a cylindrical shape, the first casing has a disk shape, and the ribs are continuously arranged in the circumferential direction so as to sequentially connect the plurality of bolt seats arranged in the circumferential direction. The casing structure of the in-wheel motor drive device of Claim 3 or 4. The in-wheel motor drive device further includes a speed reduction unit that decelerates the output rotation of the motor unit and transmits it to the wheel hub bearing unit,
The speed reduction part is inputted with rotation from the output shaft of the motor part, and has an input shaft having a plurality of eccentric parts provided at different positions in the axial direction;
A plurality of revolving members that are respectively held in the eccentric portion so as to be relatively rotatable, and perform a revolving motion around the axis of the input shaft as the input shaft rotates;
An outer periphery engaging member that engages with the outer periphery of the revolving member to cause the revolving motion of the revolving member;
The in-wheel according to claim 1, further comprising: a motion conversion mechanism that converts the rotational motion of the revolving member into a rotational motion centering on an axis of the input shaft and outputs the rotational motion to the wheel hub bearing portion. The casing structure of the motor drive device.

Images