JP2013035368A - Bearing device for driving wheel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a bearing device for a driving wheel more compact and light in weight, by reducing a dimension in a shaft direction without making an outer diameter dimension thereof large.SOLUTION: The bearing device for the driving wheel includes a hub 10, a double row rolling bearing 20, and an outboard side constant velocity joint 30. A contact angle α of an outboard side rolling element row 26a of the double row rolling bearing 20 is made equal to a contact angle α of an inboard side rolling element row 26b, and a pitch circle diameter PCDo of the outboard side rolling element row 26a is made larger than a pitch circle diameter PCDi of the inboard side rolling element row 26b. The outboard side constant velocity joint 30 is disposed at the outboard side compared with the double row rolling bearing 20, and a center O of the outboard side constant velocity joint 30 is disposed on the inside of the bearing span of the double row rolling bearing 20.

Description

  The present invention relates to a drive wheel bearing device in which a double row rolling bearing and a constant velocity joint for rotatably supporting a drive wheel of a vehicle on a vehicle body are integrated.

  Patent Document 1 describes a wheel bearing device for a drive wheel. In other words, a hub for mounting a disc wheel is rotatably supported on the vehicle body via a double-row rolling bearing, and a drive shaft is inserted into a through hole provided in the hub, and the joint inner ring is fixed to the end of the drive shaft. A portion corresponding to the outer ring of the joint is formed inside the hub, and a ball is interposed between the two to constitute a ball type constant velocity joint on the outboard side of the double row rolling bearing.

  Referring to FIG. 5, in the wheel bearing device 110, the inner ring 122 is attached to the outer periphery of the shaft portion 114 of the hub 112, and the outer peripheral surface of the shaft portion 114 and the outer peripheral surface of the inner ring 122 are connected to each other. The inner ring raceway surface. The outer member 125 having the outer ring raceway surface of the double row rolling bearing 120 is attached to the knuckle 128 of the vehicle body. Balls 126 and 127 are arranged as rolling elements in a double row between the inner ring raceway surface formed on the shaft portion 114 and the inner ring 122 and the outer ring raceway surface formed on the outer member 125, The part 114 and the inner ring 122 are rotatably supported. The shaft portion 114 and the inner ring 122 are integrated by caulking the end portion 116 of the shaft portion 114 against the side end portion 124 of the inner ring 122 of the double row rolling bearing 120. Thus, the wheel bearing device 110 is attached to the vehicle body via the double row rolling bearing 120.

  A through hole 118 is formed at the center of the shaft portion 114, and the drive shaft 140 is inserted into the through hole 118. A constant velocity joint 130 is provided on the outboard side of the double row rolling bearing 120 so as to connect the shaft portion 114 and the drive shaft 140 so as to be swingable. An inner ring 134 as an inner joint member constituting the constant velocity joint 130 is fixed to an end portion of the drive shaft 140, and an outer ring equivalent portion 132 as an outer joint member is formed on the inner peripheral surface of the through hole 118 of the shaft portion 114. It is. That is, the end portion on the outboard side of the through hole 118 is a partially spherical inner peripheral surface, and ball grooves 136 extending in the axial direction are formed at equal intervals in the circumferential direction on the inner peripheral surface.

  The wheel bearing device described in Patent Document 1 has the following advantages. That is, since the constant velocity joint 130 is formed inside the through hole 118 of the hub 112, the torque of the drive shaft 140 can be transmitted directly from the constant velocity joint 130 to the hub 112. As a result, the spline connection between the shaft portion of the hub and the shaft portion of the constant velocity joint outer ring can be eliminated. Therefore, the problem of abnormal noise occurring at the spline coupling portion is also solved. Further, since torque can be directly transmitted from the constant velocity joint 130 to the shaft portion 114 of the hub 112 on the outer periphery thereof, the outer constant ring of the constant velocity joint can be downsized, and the constant velocity joint 130 and thus the wheel bearing device 110 can be reduced in size. And weight reduction can be achieved.

JP 2009-241617 A

  In the wheel bearing device described in Patent Document 1, since the constant velocity joint 130 is arranged on the outboard side of the double row rolling bearing 120, the inner ring raceway and the outer ring are equivalent to the outboard side of the double row rolling bearing 120. If the wall thickness between the portions 132 is secured, the axial length is increased and the weight is increased. In order to shorten the axial length, it is conceivable to increase the ball PCD (pitch circle diameter) of the double row rolling bearing 120. There is no choice but to increase the outer diameter of 125, and eventually the weight increases as in the former case.

  The main object of the present invention is to further shorten the axial dimension without increasing the outer diameter of the drive wheel bearing device, thereby making it possible to further reduce the size and weight.

The present invention provides a double row rolling bearing with an outboard-side rolling element row having a pitch circle diameter larger than a pitch circle diameter of an inboard-side rolling element row. The problem is solved by inserting a constant velocity joint inside the board-side rolling element array.
That is, the drive wheel bearing device of the present invention comprises a double row rolling bearing comprising a double row inner ring raceway, a double row outer ring raceway, a double row rolling element, and a cage for holding each row rolling element. ,
A hub having a through hole in the shaft center part, a flange for attaching a wheel to the outer periphery, and rotatably supported by the double row rolling bearing;
A portion corresponding to the outer joint member formed integrally with the hub, an inner joint member fixed to the end of the drive shaft inserted into the through hole of the hub, and between the outer joint member and the inner joint member An outboard side constant velocity joint having a ball for torque transmission between the two, and the pitch circle diameter of the outboard side rolling element row of the double row rolling bearing is defined as the pitch of the inboard side rolling element row. Larger than the circle diameter,
The outboard side constant velocity joint is arranged on the outboard side from the double row rolling bearing, and the center of the outboard side constant velocity joint is arranged inside the bearing span of the double row rolling bearing. It is what.
Conventionally, when the outboard side constant velocity joint is arranged on the outboard side of the double row rolling bearing, the center of the outboard side constant velocity joint is located outside the bearing span of the double row rolling bearing. The center dimension of the outboard side constant velocity joint is disposed inside the bearing span of the double row rolling bearing, in other words, the axial dimension can be shortened by moving the center of the outboard side constant velocity joint toward the inboard side.
At that time, simply moving the outboard side constant velocity joint toward the inboard side so that the center of the outboard side constant velocity joint is inside the bearing span of the double row rolling bearing, the outer ring of the outboard side constant velocity joint It becomes difficult to secure the wall thickness between the ball groove and the track of the outboard side rolling element row. Therefore, the thickness can be ensured by increasing the pitch circle diameter of the outboard side rolling element row, specifically, by making it larger than the pitch circle diameter of the inboard side rolling element row. Again, instead of simply increasing the pitch circle diameter of the outboard-side rolling element row at the same axial position, it is possible to increase the pitch circle diameter without changing the bearing span and contact angle of the double row rolling bearing. Since the position of the orbit of the side rolling element row moves not only in the radial direction but also in the axial direction, a larger thickness can be ensured.

According to the present invention, the pitch circle diameter of the outboard side rolling element row (hereinafter simply referred to as the outer row) among the rolling element rows of the double row rolling bearing is the same as that of the inboard side rolling element row (hereinafter simply referred to as the inner row). By making it larger than the pitch circle diameter, it is possible to reduce the axial dimension by inserting a part corresponding to the outer ring of the constant velocity joint inside the outer row, realizing a compact and lightweight drive wheel bearing device. To do.
The outer row and inner row may have the same rolling element size, but may be different. By making the outer row and the inner row have the same rolling element size, there is no risk of incorrect assembly of the rolling elements, that is, the incorporation of rolling elements of different sizes. Moreover, it can be produced without increasing the number of parts (rolling elements of different sizes). Even if the rolling element size is the same, it is possible to increase the number of rolling elements in the outer row as the pitch circle diameter is increased. As a result, the bearing rigidity is increased.
On the other hand, it is also possible to increase the number of rolling elements by reducing the size of the rolling elements of the outer row, thereby further increasing the bearing rigidity. That is, since the outer row having a larger pitch circle diameter can afford the bearing life, it is possible to reduce the size of the rolling elements to increase the number of rolling elements and to distribute the bearing stiffness. The outer diameter of the outer ring inner ring raceway is increased by increasing the pitch circle diameter and further reducing the rolling element size. Accordingly, the thickness between the outer ring equivalent portion and the outer ring equivalent portion increases accordingly, and if the thickness is constant, the outer ring equivalent portion can be brought closer to the double row rolling bearing side.

It is a longitudinal cross-sectional view which shows a 1st Example. It is a figure similar to FIG. 1 for demonstrating a bearing span. It is a longitudinal cross-sectional view which shows a 2nd Example. It is a longitudinal cross-sectional view which shows a 3rd Example. It is a longitudinal cross-sectional view which shows the prior art.

  First, referring to FIG. 1 showing the first embodiment, the drive wheel bearing device includes a hub 10, a double row rolling bearing 20, and a constant velocity joint 30.

  The hub 10 is a rotating body including a wheel pilot 12, a flange 14, and a shaft portion 16 in order from the left side of FIG. 1, and has a through hole 18 in the shaft center portion. The flange 14 is integrally formed on the outer periphery of the hub 10. A disk wheel (not shown) is attached to the flange 14, and a wheel nut (not shown) is fastened to the hub bolt 15 to be fastened. At this time, the disk pilot is centered by the wheel pilot 12. A first inner ring raceway 16a, a shoulder 16b, a small diameter portion 16c, and a caulking portion 16d are formed in this order on the outer peripheral surface of the shaft portion 16 from the base side of the flange 14 toward the shaft end portion. The through-hole 18 of the hub 10 is an outer end portion 18a, a joint outer ring equivalent portion 18b, an intermediate portion 18c, and an inner end portion 18d in order from the left side in FIG.

  A bearing ring 22, which is separate from the hub 10, is attached to the small diameter portion 16 c of the shaft portion 16 of the hub 10. A shoulder surface 22 a and a second inner ring raceway 22 b are formed on the outer peripheral surface of the raceway ring 22. The race ring 22 is fitted to the small diameter portion 16c, and the shaft end portion of the small diameter portion 16c is bent and expanded toward the outer diameter side with the end face of the race ring 22 being in contact with the shoulder 16b. 22 is fixed. FIG. 1 shows a state after caulking. The first inner ring raceway 16 a formed directly on the hub 10 and the second inner ring raceway 22 b formed on the race ring 22 constitute an inner ring raceway of the double row rolling bearing 20. That is, the hub 10 and the bearing ring 22 correspond to the bearing inner ring of the double row rolling bearing 20.

An outer member 24 corresponding to a bearing outer ring of the double row rolling bearing 20 has double row outer ring raceways 24a and 24b on the inner periphery, and is fastened with bolts to a knuckle (not shown) of the vehicle body on the outer periphery. A threaded flange 24c is integrally formed. One end face of the outer member 24 is provided with a cylindrical protrusion (knuckle pilot) 24d for fitting with a knuckle hole.
Seals 28 a and 28 b are attached to both ends of the outer member 24. One seal 28a is attached to the inner peripheral surface 24e of the end of the outer member with the seal lip elastically contacting the seal surface 16e formed at the base of the flange 14 of the hub 10. The other seal 28 b is attached between the shoulder surface 22 a of the race ring 22 and the end inner peripheral surface 24 f of the outer member 24.

Double row rolling elements, that is, balls 26a and 26b, are interposed between the inner ring raceways 16a and 22b and the outer ring raceways 24a and 24b. Reference numeral 26a indicates a ball row on the outboard side, that is, an outer row, and reference numeral 26b indicates a ball row on the inboard side, that is, an inner row. As shown in FIG. 2, the pitch circle diameter PCDo of the outer row 26a is larger than the pitch circle diameter PCDi of the inner row 26b. In FIG. 2, the contact angle is indicated by α, and the outer row 26 a and the inner row 26 b have the same contact angle. Here, the contact angle is defined as an angle formed by a plane (radial plane) perpendicular to the bearing center axis and a line of action of the resultant force transmitted to the rolling elements by the raceway. Further, the point where the resultant force transmitted to the row of rolling elements by the raceway intersects the bearing central axis is referred to as an action point, which is indicated by the symbol Po and the action point Pi in FIG. The distance between the action point Po on the outboard side and the action point Pi on the inboard side is called a bearing span. Here, the bearing span is represented as (Po to Pi).
When the outer member 24 of the double row rolling bearing 20 configured as described above is fixed to the vehicle body, the hub 10 is rotatably supported by the double row rolling bearing 20.

  The constant velocity joint 30 includes an inner ring 32 as an inner joint member, the joint outer ring equivalent portion 18b as an outer joint member, a ball 36 as a torque transmission member, and a cage 38 for holding the ball 36. The

  The inner ring 32 is fixed to the end of the drive shaft 90 inserted into the through hole 18 of the hub 10. The inner ring 32 and the drive shaft 90 are fitted together so as to be able to transmit torque by, for example, spline or serration, and are prevented from coming off by a retaining ring 92. The inner ring 32 has a partially spherical outer peripheral surface 32a, and ball grooves 32b extending in the axial direction are formed on the outer peripheral surface 32a at equal intervals in the circumferential direction.

The joint outer ring equivalent portion 18b has a partially spherical inner peripheral surface 34a, and ball grooves 34b extending in the axial direction are formed at equal intervals in the circumferential direction on the outer peripheral surface 34a.
The ball groove 32b of the inner ring 32 and the ball groove 34b of the joint outer ring equivalent part 18b make a pair, and one ball 36 is interposed between each pair of ball grooves 32b, 34b.

  The ball 36 is accommodated in a pocket 38 a of the cage 38. The pockets 38a are arranged at predetermined intervals in the circumferential direction of the cage 38, and each pocket 38a penetrates the cage 38 in the radial direction. The inner and outer peripheral surfaces of the cage 38 are partially spherical, the inner peripheral surface is in spherical contact with the outer peripheral surface 32a of the inner ring 32, and the outer peripheral surface is in spherical contact with the inner peripheral surface 34a of the joint outer ring equivalent portion 18b.

  The center of curvature of the ball groove 32b of the inner ring 32 and the center of curvature of the ball groove 34b of the outer ring corresponding portion 18b are offset by an equal distance from each other in the axial direction relative to the joint center. That is, the center of curvature of the ball groove 32b of the inner ring 32 is offset by a distance (assumed to be F1) from the joint center to the right side in FIG. 1, and the center of curvature of the ball groove 34b of the outer ring equivalent portion 18b is the center of the joint. Is offset by an equal distance (F1) to the left side of FIG. As a result, the ball track formed by the paired ball grooves 32b and 34b has a wedge shape which is gradually reduced from one to the other in the axial direction, or from left to right in the case of FIG. Therefore, when the constant velocity joint 30 rotates at an operating angle, in other words, when the inner ring 32 and the joint outer ring equivalent portion 18b rotate at an angle, the ball 36 accommodated in the ball track is wedged. Receives a force toward the direction of shape expansion. Since all the balls 36 are held in the same plane by the cage 38, the balls 36 that are 180 degrees out of phase with the balls 36 that receive the above force receive a force in the opposite direction. In this way, the distance from the ball center to the rotation axis of the inner ring 32 and the distance from the ball center to the rotation axis of the joint outer ring equivalent portion 18b are always equal, and therefore the angular velocity is constant regardless of the operating angle.

  The constant velocity joint 30 is located on the outboard side (left side in FIG. 1) from the double row rolling bearing 20. Specifically, the axial position of the ball 36 of the constant velocity joint 30 is located on the outboard side (left side in FIG. 1) with respect to the outer row 26 a of the double row rolling bearing 20. More specifically, as shown in FIG. 2, the center O of the constant velocity joint 30 is arranged inside the bearing span (Po to Pi) of the double row rolling bearing 20. FIG. 1 shows a state where the constant velocity joint 30 does not take an operating angle, that is, a case where the inner ring 32 and the joint outer ring equivalent portion 18b are in a coaxial state. Obviously, the outer row 26a is located on the outboard side.

  The number of the balls 36 of the constant velocity joint 30 is arbitrary, but for example, one using six or eight balls is known. When eight balls are used, the load capacity per ball can be reduced as the number of balls is increased as compared with the case where six balls are used, so that the ball diameter can be reduced. As a result, the pitch circle diameter can be reduced, and the outer diameter is accordingly reduced. Therefore, the constant velocity joint can be reduced in size and size, and as a result, the entire drive wheel bearing device can be reduced in size.

  The ball 36 of the constant velocity joint 30 has a larger diameter than the balls 26 a and 26 b of the double row rolling bearing 20. As shown in FIG. 2, when the pitch circle diameter of the balls 36 is PCDj, the pitch circle diameter of the inner row is PCDi, and the pitch circle diameter of the outer row is PCDo, in a state where the constant velocity joint 30 does not take an operating angle, PCDj <PCDi <PCDo. The outer diameter of the inner ring raceway 22b in the inner row is about the same as the PCDj of the ball 36, whereas the outer diameter of the inner ring raceway 16a in the outer row 22a is about the same as the circumscribed circle of the ball 36.

A boot 40 and a cap 48 are attached as means for preventing leakage of grease filled in the constant velocity joint 30 and preventing foreign matter from entering from the outside.
The boot 40 is for sealing the opening of the inner end 18 d of the hub 18, and includes a boot body 42 and a boot adapter 44. The boot body 42 is formed by forming a flexible material such as rubber or elastomer into a conical trapezoidal shape as illustrated. The boot adapter 44 is a metal two-stage cylindrical shape, and includes a small diameter portion 44a, a large diameter portion 44b, and a flange portion 44c connecting the both. The small diameter portion 44 a is press-fitted into the inner end portion 18 d of the through hole 18 of the hub 10, and the flange portion 44 is brought into contact with the caulking portion 16 d of the hub 10 for positioning. An annular groove may be provided in the small-diameter portion 44a to mount an O-ring. Both ends are integrated by bending the end of the large diameter portion 44b inward and winding the large diameter portion 42a of the boot body 42. The small-diameter portion 42 b of the boot main body 42 is fitted into a boot groove 94 formed in the drive shaft 90 and is fastened and fixed by a boot band 46.
The cap 48 is formed by press-molding a thin metal plate into a tray shape, and is press-fitted into the outer end 18 a of the through hole 18 of the hub 10.

  As described above, by making the pitch circle diameter of the outer row 26a out of the rolling element rows 26a, 26b of the double row rolling bearing 20 larger than the pitch circle diameter of the inner row 26b, it is equivalent to the joint outer ring inside the outer row 26a. There can be enough room for the portion 18b to be inserted. Therefore, it is possible to shorten the axial dimension of the outer row 26a and the constant velocity joint 30, and as a result, the entire driving wheel bearing device can be made compact and light. If this is described with reference to FIG. 2, the center O of the outboard side constant velocity joint 30 is arranged inside the bearing span (Po to Pi) of the double row rolling bearing 20, in other words, the outboard side constant velocity joint. The axial dimension can be shortened by moving the center O of the joint 30 toward the inboard side. Further, simply moving the outboard side constant velocity joint 30 toward the inboard side so that the center O of the outboard side constant velocity joint 30 is located inside the bearing span (Po to Pi) of the double row rolling bearing 20, It becomes difficult to ensure the thickness between the outer ring ball groove 34b of the outboard side constant velocity joint 30 and the inner ring raceway 16a for the outer row 26a. Therefore, by increasing the pitch circle diameter PCDo of the outer row 26a, specifically, by making it larger than the pitch circle diameter PCDi of the inner row 26b, the wall thickness can be ensured. Here, not only the pitch circle diameter PCDo of the outer row 26a is simply increased at the same axial position, but also the pitch circle diameter PCDo is changed without changing the bearing span (Po to Pi) of the double row rolling bearing 20 and the contact angle α. By increasing the size, the position of the inner ring raceway 16a of the outer row 26a moves not only in the radial direction but also in the axial direction, so that a larger thickness can be ensured. In order to explain this, two circles are shown by two-dot chain lines in the vicinity of the solid line circle representing the rolling elements of the outer row 26a in FIG. One is on the same pitch circle diameter PCDi as the inner row 26b, and the other is on the same pitch circle diameter PCDo as the outer row 26a. The former indicates that the thickness of the outer ring ball groove 34b of the outboard side constant velocity joint 30 can hardly be secured unless the pitch circle diameter is changed. The latter indicates that it is not possible to secure a very large wall thickness simply by increasing the pitch circle diameter.

  Various combinations of the rolling element sizes of the outer row 26a and the inner row 26b are possible depending on the purpose. The outer row 26a and the inner row 26b may have the same or different rolling element sizes. When the outer row 26a and the inner row 26b have the same rolling element size, there is no risk of incorrect assembly of the rolling elements, that is, the incorporation of rolling elements having different sizes. Moreover, it can be produced without increasing the number of parts (rolling elements of different sizes). On the other hand, the bearing rigidity can be increased by reducing the size of the rolling elements of the outer row and increasing the number of rolling elements. In other words, the outer row with a larger pitch circle diameter can afford a bearing life, and accordingly, the size of the rolling elements can be reduced, and the number of rolling elements can be increased and distributed to the bearing rigidity.

  Next, referring to FIG. 3 showing the second embodiment, in this embodiment, another constant velocity joint 50 is provided at the end of the drive shaft 90 opposite to the constant velocity joint 30. In this case, the former constant velocity joint 30 can be called an outboard joint, and the latter constant velocity joint 50 can be called an inboard joint. The outboard joint 30 is a fixed joint capable of only angular displacement, whereas the inboard joint 50 is a sliding joint capable of not only angular displacement but also axial displacement (plunging). The hub 10, the double row rolling bearing 20, and the outboard joint 30 are the same as those in the embodiment of FIG.

The inboard joint 50 is a tripod type, and includes a tripod 52 as an inner joint member, a housing 54 as an outer joint member, and a roller assembly 56 as a torque transmission member, and is used with the boot 60 mounted. It is common.
The tripod 52 includes a boss 52 a and a trunnion journal 52 b, and the boss 52 a is fixed to the end of the drive shaft 90. The boss 52a and the drive shaft 90 are fitted together so as to be able to transmit torque by, for example, spline or serration, and are prevented from coming off by a retaining ring 98. Three trunnion journals 52b are arranged at equal intervals in the circumferential direction of the boss 52a, and project in the radial direction of the boss 52a. Each trunnion journal 52b has a cylindrical shape, and an annular groove 52c is formed on the shaft end side.

  A roller assembly 56 is attached to each trunnion journal 52b. The roller assembly 56 includes a roller 56a, a plurality of needle rollers 56b, a washer 56c, and a circlip 56d. The roller 56a has a cylindrical inner peripheral surface and a spherical outer peripheral surface, and needle rollers 56b are interposed between the cylindrical inner peripheral surface of the roller 56a and the cylindrical outer peripheral surface of the trunnion journal 52b. The washer 56c is located closer to the shaft end of the trunnion journal 52b than the end of the needle roller 56b. The washer 56c has a ring shape with an L-shaped cross section, and includes a cylindrical portion and an inward flange positioned at the inner end of the cylindrical portion. Further, the outer diameter of the cylindrical portion of the washer 56c is smaller than the inner diameter of the roller 56a, and the cylindrical portion is enlarged at the outer end portion to be larger than the inner diameter of the roller 56a. The circlip 56d is mounted in the annular groove 52c of the trunnion journal 52b and prevents the washer 56c from coming off from the shaft end of the trunnion journal 52b.

  The housing 54 has a cup shape opened at one end, and has a track groove extending in the axial direction at a position equally divided into three in the circumferential direction, and a side wall surface of each track groove is a roller guide surface. The roller guide surface has a partially cylindrical shape, and the contour of the roller guide surface 54b in a cross section perpendicular to the axis of the housing 54 has a shape matching the outer peripheral surface shape of the roller 56a, for example, an arc shape here. The housing 54 integrally has a connecting shaft portion 54c.

  In assembling the inboard joint 50, a subassembly including the tripod 52 and the roller assembly 56 is inserted into the housing 54, and the roller 56a is accommodated in the track groove. Although not shown, it is common to provide a retaining means for preventing the subassemblies 52 and 56 from coming out of the housing 54. As an example, a retaining clip is attached to the opening end of the housing 54 (see FIG. 3).

  The boot 60 is formed of a flexible material such as rubber or elastomer. Here, an intermediate portion 64 having a bellows shape and a large-diameter end portion 62 and a small-diameter end portion 66 provided at both ends thereof are illustrated. The large-diameter end portion 62 is attached to the housing 54, and the small-diameter end portion 66 is attached to a boot groove 96 formed in the drive shaft 90, and each is fastened and fixed by a boot band 68. By mounting the boot 60, it is possible to prevent leakage of grease filled in the constant velocity joint and to prevent foreign matter from entering from the outside.

  Next, referring to FIG. 4 showing the third embodiment, the drive shaft 90A is a short shaft and is sealed with a single boot 80 from the shaft end of the hub 10 to the outer ring 74 of the inboard joint 70. Here, the outboard joint 30 and the inboard joint 70 are common in that both are constant velocity ball joints using balls as torque transmitting members. Further, the inboard joint 70 is common to the embodiment of FIG. 3 in that it is a sliding type, but is different in that it is a double offset type compared to the tripod type in FIG. . The hub 10, the double row rolling bearing 20, and the outboard joint 30 are the same as already described with reference to FIG.

The inboard joint 70 includes an inner ring 72, an outer ring 74, a ball 76, and a cage 78, and is used in a state in which a boot 80 is mounted.
The inner ring 72 is fixed to the end of the drive shaft 90A. The inner ring 72 and the drive shaft 90A are fitted together so as to be able to transmit torque by, for example, spline or serration, and are prevented from coming off by a retaining ring 98A. The inner ring 72 has a partially spherical outer peripheral surface 72a, and linear ball grooves 72b are formed at equal intervals in the circumferential direction on the outer peripheral surface 72a.
The outer ring 74 has a cylindrical inner peripheral surface 74a, and linear ball grooves 74b are formed at equal intervals in the circumferential direction on the outer peripheral surface 74a.
The ball groove 72b of the inner ring 72 and the ball groove 74b of the outer ring 74 make a pair, and one ball 76 is interposed between each pair of ball grooves 72b and 74b.

  Each ball 76 is accommodated in a pocket 78 a of the cage 78. The pockets 78a are arranged at predetermined intervals in the circumferential direction of the cage 78, and each pocket 78a penetrates the cage 78 in the radial direction. The cage 78 has an annular shape, and a partial spherical portion 78b that is in spherical contact with the partial spherical outer peripheral surface 72a of the inner ring 72 is formed on the inner peripheral surface thereof. On the outer peripheral surface of the cage 78, a partial spherical portion 78c that is in line contact with the partial cylindrical inner peripheral surface 74a of the outer ring 74 is formed.

  The center of curvature of the partial spherical portion 78b on the inner peripheral surface of the cage 78 and the center of curvature of the partial spherical portion 78c on the outer peripheral surface are offset from each other in the axial direction by an equal distance from the joint center. Yes. That is, the center of curvature of the partial spherical portion 78b on the inner peripheral surface is offset by a distance (assumed to be F2) from the joint center to the right side in FIG. 4, and the center of curvature of the partial spherical portion 78c on the outer peripheral surface is , Offset by an equal distance (F2) from the joint center to the left side of FIG.

  FIG. 4 is an example in which a retaining clip 75 is attached to the opening end of the outer ring 74 as a retaining means for preventing the inner ring 72 from slipping out of the outer ring 74. The clip 75 is divided at a part in the circumferential direction, and is attached to a circumferential groove 74c formed in the outer ring 74 using elastic deformation. Since the inner diameter of the clip 75 in the mounted state is set smaller than the circumscribed circle diameter of the ball 76, when the inner ring 72 tries to slide out from the opening of the outer ring 74, the ball 76 interferes with the clip 75 and is prevented from coming off. The

  The boot 80 is for sealing the opening of the inner end portion 18 d of the hub 10, and includes a boot body 82 and a boot adapter 84. The boot body 82 is formed by molding a flexible material such as rubber or elastomer into a cross-sectional shape as illustrated. The boot adapter 84 has a metal two-stage cylindrical shape, and includes a small diameter portion 84a, a large diameter portion 84b, and a flange portion 84c that connects the two. The small diameter portion 84 a is press-fitted into the inner end portion 18 d of the through hole 18 of the hub 18, and the flange portion 84 c is positioned against the caulking portion 16 d of the hub 10 for positioning. An annular groove may be provided in the small diameter portion 84a and an O-ring may be attached. Both ends are integrated by bending the edge of the large diameter portion 84b outward and winding the small diameter portion 82b of the boot body 82. The large-diameter portion 82 a of the boot body 82 is attached to the outer ring 74 of the inboard joint 70 and is fastened and fixed by the boot band 86.

Although the embodiments of the present invention have been described based on the examples illustrated in the drawings, various modifications can be made in carrying out the present invention. For example, in the above description, one of the inner ring raceways (first inner ring raceway 16a) of the double row rolling bearing 20 is formed directly on the hub 10, and the other (second inner ring raceway 22b) is separated from the hub 10. Although the case where it is formed on the body race ring 22 is taken as an example, both may be formed on a race ring separate from the hub.
Further, as an example of a double row rolling bearing, a ball bearing using balls as rolling elements has been taken as an example. However, it is also possible to use tapered rollers as rolling elements.

DESCRIPTION OF SYMBOLS 10 Hub 12 Wheel pilot 14 Flange 15 Hub bolt 16 Shaft part 16a First inner ring raceway 18 Through-hole 20 Double row rolling bearing 22 Track ring 22b Second inner ring raceway 24 Outer member 24a, 24b Outer ring raceway 25 Cage 26a Outer row 26b Inner row 28a, 28b Seal 30 Outboard joint (fixed constant velocity joint)
32 Inner ring (inner joint member)
34 Outer ring (outer joint member)
36 balls (torque transmission member)
38 Cage 40 Boot 42 Boot body 44 Boot adapter 46 Boot band 48 Cap 50 Inboard joint (tripod type constant velocity joint)
60 boots 70 inboard joints (double offset constant velocity joints)
80 Boots 90, 90A Drive shaft

Claims (11)

A double-row rolling bearing comprising a double-row inner ring raceway, a double-row outer ring raceway, a double-row rolling element, and a cage for holding each row of rolling elements,
A hub having a through hole in the shaft center part, a flange for attaching a wheel to the outer periphery, and rotatably supported by the double row rolling bearing;
A portion corresponding to the outer joint member formed integrally with the hub, an inner joint member fixed to the end of the drive shaft inserted into the through hole of the hub, and between the outer joint member and the inner joint member An outboard side constant velocity joint having a ball for torque transmission between the two, and the pitch circle diameter of the outboard side rolling element row of the double row rolling bearing is defined as the pitch of the inboard side rolling element row. Larger than the circle diameter,
The outboard side constant velocity joint is arranged on the outboard side from the double row rolling bearing, and the center of the outboard side constant velocity joint is arranged inside the bearing span of the double row rolling bearing. Drive wheel bearing device.   2. The drive wheel bearing device according to claim 1, wherein a contact angle of the outboard side rolling element row of the double row rolling bearing is equal to a contact angle of the inboard side rolling element row.   The double-row inner ring raceway includes a first inner ring raceway formed on the outer peripheral surface of the shaft portion of the hub and a second inner ring raceway formed on a raceway ring attached to the shaft portion of the hub. 3. The drive wheel bearing device according to claim 1, wherein the outer ring raceway of the row is formed on an outer member for mounting to the vehicle body.   The bearing device for a drive wheel according to claim 1, 2 or 3, wherein the outboard side rolling element row and the inboard side rolling element row of the double row rolling bearing are balls of the same diameter.   The drive wheel bearing device according to any one of claims 1 to 4, wherein the number of rolling elements in the outboard side rolling element row of the double row rolling bearing is greater than the number of rolling elements in the inboard side rolling element row.   The rolling element size of the outboard side rolling element row of the double row rolling bearing is made smaller than the rolling element size of the inboard side rolling element row, and the number of rolling elements of the outboard side rolling element row is set to the inboard side rolling element. 4. The bearing device for a drive wheel according to claim 1, wherein the number of rolling elements in the row is larger.   The outboard side constant velocity joint includes an inner joint member having eight ball grooves formed on the outer periphery, an outer joint member having eight ball grooves formed on the inner periphery, and a ball groove of a pair of inner joint members. A ball that is interposed between the ball grooves of the outer joint member, and a cage that is interposed between the outer peripheral surface of the inner joint member and the inner peripheral surface of the outer joint member and holds the balls in the same plane, The drive wheel bearing device according to any one of claims 1 to 6, wherein the outer joint member is formed integrally with the hub.   The bearing device for a drive wheel according to any one of claims 4 to 7, wherein a ball of the outboard side constant velocity joint has a larger diameter than a rolling element of the double row rolling bearing.   The drive wheel bearing device according to claim 1, wherein a boot is attached between the shaft portion of the hub and the drive shaft.   The drive wheel bearing device according to any one of claims 1 to 9, wherein an inboard side constant velocity joint is provided at an end of the drive shaft opposite to the outboard side constant velocity joint.   An inboard side constant velocity joint is provided at the end of the drive shaft opposite to the outboard side constant velocity joint, and from the shaft portion of the hub to the outer joint member of the inboard side constant velocity joint. 9. The drive wheel bearing device according to claim 1, wherein the drive wheel bearing device is sealed with a single boot.

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