JP4338095B2 - Drive wheel bearing unit - Google Patents

Description

 The present invention relates to a bearing unit for driving wheels (front wheels of FF vehicles, rear wheels of FR vehicles, all wheels of 4WD vehicles) of automobiles.

  As shown in FIG. 32, the drive shaft 1 that transmits the power from the engine to the drive wheels includes a fixed type constant velocity universal joint J1 on the outboard side (the side of the vehicle body in the vehicle width direction) and the inboard side ( The intermediate shaft 2 is connected to a sliding type constant velocity universal joint J2 on the vehicle center side in the vehicle width direction. The constant velocity universal joint J1 (outboard side constant velocity universal joint) on the outboard side is coupled to the hub wheel 4 rotatably supported by the wheel bearing 3, and the constant velocity universal joint J2 (inboard side) on the inboard side. A constant velocity universal joint) is coupled to the differential 5.

  The wheel bearing 3 is arranged in double rows between a bearing inner ring 3a fixed to the outer periphery of the hub wheel 4, a bearing outer ring 3b fixed to a knuckle member 6 extending from a suspension on the vehicle body side, and a bearing inner ring 3a and a bearing outer ring 3b. And rolling elements 3c. Usually, both are fixed by press-fitting the bearing inner ring 3 a on the outer periphery of the hub ring 4. The bearing outer ring 3b and the knuckle member 6 are usually fixed by bolting the flange 3b1 of the bearing outer ring 3b to the knuckle member 6.

The conventional assembly of the drive shaft 1 to the vehicle is performed in a state where the hub wheel 4 and the wheel bearing 3 are fixed to the knuckle member 6 in advance, and the shaft end on the outboard side of the drive shaft 1 (the stem portion 7a of the outer joint member 7). ) Is inserted into the inner periphery of the hub wheel 4 and a nut 8 is screwed onto the shaft end protruding from the hub wheel 4 (see, for example, Patent Document 1). As the nut 8 is tightened, the entire drive shaft 1 slides toward the outboard side, and the shoulder 7b of the outer joint member 7 comes into contact with the end surface of the bearing inner ring 3a. As a result, the outer joint member 7 and the hub wheel 4 are positioned in the axial direction, and a predetermined preload is applied to the wheel bearing 3. The outer peripheral surface of the stem portion 7a of the outer joint member 7 and the inner peripheral surface of the hub wheel 4 are coupled by a spline (not shown), and the driving force of the engine transmitted to the outer joint member 7 is the spline and further the hub wheel 4 It is transmitted to the wheel via.
JP 2004-270855 A

  However, in the above-described conventional process, the knuckle member 6 assembled with the wheel bearing 3 and the hub wheel 4 is made to wait in advance at a position rotated from the neutral position around the kingpin center, and in this state, the outboard side constant velocity universal joint The complicated work of fixing J1 to the hub wheel 4 and further fixing the inboard side constant velocity universal joint J2 to the differential 5 after returning the knuckle member 6 to the neutral position is required. In addition, many fastening operations such as bolting of the bearing outer ring 3b to the knuckle member 6 and tightening of the nut 8 are required. Therefore, the assembly process of the drive shaft is complicated, and this point is a factor of high cost. Moreover, many nuts and bolts are required, and the number of parts is also disadvantageous in terms of cost. Further, since the drive shaft turns with the turning of the knuckle member, a large work space is required.

  By the way, the tightening operation of the nut can be omitted by previously connecting and integrating the outer joint member 7 of the outboard side constant velocity universal joint J1 and the hub wheel 4. However, since a large load acts on the joint between the two, including the moment load during cornering, as the vehicle travels, the joint structure has a high strength that can withstand this and is inexpensive. Needed.

  Therefore, the main object of the present invention is to couple the hub wheel and the outer joint member with high strength without using a nut.

  In addition, the main purpose is to reduce the number of parts, simplify the structure, and reduce the cost.

(1) In order to achieve the above object, the present invention includes an outer member having a plurality of outer races on the inner periphery, and a hub wheel provided with a flange for attachment to a wheel, and a plurality of members facing the outer race. In a drive wheel bearing unit comprising an inner member having an inner race, a plurality of rows of rolling elements arranged between the outer race and the inner race facing each other, and a constant velocity universal joint on the outboard side,
One of the outer joint members of the hub wheel and the outboard side constant velocity universal joint is provided with a male part having a tooth-shaped surface, the male part is provided on the other side, and the female part having a different cross-sectional shape from the male part Having a coupling portion formed by axially press-fitting into
The coupling part is completed by biting into the female part of the male part accompanying the press-fitting.

  In this case, since the plastic flow generated by the press-fitting will fill a part or all of the gap existing in the joint between the male part and the female part, the male part and the female part should be firmly coupled and integrated. Can do. In addition, since this connection is performed simply by press-fitting either one of the male part and the female part into the other, the workability is good. Since the male part and female part can be firmly connected, in the configuration where the stem part is provided on the outer joint member of the constant velocity universal joint on the outboard side, the axial length of the joint part of the male part and female part is the radius of the stem part. It can be below the dimension.

(2) By making the male part harder than the female part, the teeth of the male part can be surely bitten into the female part, so that the bonding strength can be increased.

(3) In the above configuration, the outer peripheral surface of the outer member is fitted to the inner peripheral surface of the knuckle member on the vehicle body side, and the maximum outer diameter of the constant velocity universal joint on the outboard side is determined from the minimum inner diameter of the knuckle member. It is desirable to make it smaller. The outer peripheral surface of the outer member can be formed in a cylindrical surface shape. Here, the term “constant velocity universal joint” includes accessories such as boots and boot bands (the same applies to the following inboard constant velocity universal joints). The maximum outer diameter of the outboard constant velocity universal joint including these accessories is set smaller than the minimum inner diameter of the knuckle member.
From such a configuration, the outer unit of the constant velocity universal joint on the outboard side and the hub wheel are coupled, and the outer member is fitted to the knuckle member from the outboard side, thereby fixing the bearing unit to the knuckle member. Is possible. Such an operation can be performed simply by pushing the bearing unit in the axle direction. Therefore, the work of assembling the bearing unit to the vehicle can be simplified.

(4) The outer peripheral surface of the outer member is fitted to the inner peripheral surface of the knuckle member on the vehicle body side, and the inboard side constant velocity universal joint is connected to the outboard side constant velocity universal joint via the intermediate shaft. By making the maximum outer diameter of the constant velocity universal joint smaller than the minimum inner diameter of the knuckle member, the drive wheel bearing unit, the drive shaft having the constant velocity universal joint on the outboard side and the inboard side, and the hub wheel Can be assembled to the vehicle body in an integrated assembly state. This assembly is performed by sequentially inserting the inboard side constant velocity universal joint and the outboard side constant velocity universal joint into the inner periphery of the knuckle member, and then fitting the outer member to the inner periphery of the knuckle member.

(5) In addition, a flange for attaching to the vehicle body may be formed on the outer peripheral surface of the outer member as in the conventional case. By bolting the flange to the knuckle member, the outer member can be securely fixed to the knuckle member.

(6) If the outer peripheral surface of the outer member is cylindrical, and the outer peripheral surface is press-fitted into the inner peripheral surface of the knuckle member, the outer member and the knuckle member can be firmly bonded simultaneously with the press-fitting. Moreover, there is basically no need to bolt the outer member to the knuckle member.

(7) In this case, the coupling strength between the outer member and the knuckle member is further increased by preventing the outer member from coming off the knuckle member with the retaining ring. In this case, if the outboard side of the retaining ring groove provided in the knuckle member is formed on the tapered surface, the retaining ring is guided by the tapered surface and reduced in diameter by applying a predetermined pulling force to the outer member. The knuckle member and the outer member can be separated.

(8) Further, if the retaining ring is arranged on the outboard side from the axial center line of the inboard side rolling element and the outboard side rolling element, the outer member is moved from the outboard side to the inner periphery of the knuckle member. When press-fitting into the knuckle member, the sliding distance of the retaining ring on the inner circumferential surface of the knuckle member can be reduced, so that damage to the inner circumferential surface of the knuckle member due to dragging of the retaining ring can be suppressed.

(9) It is possible to control the operating range of the compressive force generated at the time of press-fitting into the knuckle member by forming the pussies on the outer peripheral surface of the outer member. For example, when the seal member is fixed to the inner peripheral surface of the outer member, a scum portion can be formed in the outer diameter side region of the seal member on the outer peripheral surface of the outer member. In addition, a press-fitting is performed while reducing the press-fitting area and improving the press-fitting workability by providing a press-fitting area in the outer diameter area between the outer race on the inboard side and the outer race on the outboard side on the outer peripheral surface of the outer member. The preload can be reliably applied to the inside of the bearing.

(10) In each configuration described above, the bearing gap is set to an appropriate amount of negative gap. Unlike the prior art, it is not necessary to perform the preload application work by managing the tightening torque of the nut, and the preload application work is simplified.

(11) By making the PCDs of the inboard-side rolling element and the outboard-side rolling element different from each other, the load capacity can be raised in any one of the rolling element rows. Therefore, even when the load acting on the bearing portion is different between the inboard side and the outboard side, the corresponding design can be performed without extremely increasing the size of the bearing unit. The same effect can be achieved by making the diameter of the rolling elements on the inboard side and the rolling elements on the outboard side different from each other, or making the number of rolling elements on the inboard side different from the number of rolling elements on the outboard side. Can also be obtained. Two or more of these configurations (difference in PCD, difference in rolling element diameter, or difference in the number of rolling elements) may be combined. Also, the load capacity of the entire bearing unit can be increased by making at least one of the rolling element rows into a total rolling element type.

( 12 ) In the above configuration, it is desirable to press-fit the male part into the female part on the axial center line of the inboard side rolling element and the outboard side rolling element. Thereby, even when the hub wheel is slightly deformed by press-fitting, it is possible to prevent a situation in which the influence reaches the inner race.

( 13 ) As the outboard side constant velocity universal joint, one having the outer joint member, the inner joint member, and a torque transmission ball interposed between the outer joint member and the inner joint member is used.

( 14 ) The outer member may be constituted by a pair of bearing outer rings each having an outer race and a spacer interposed between the bearing outer rings. In this case, the rolling element can be assembled between the inner race and the outer race by inserting the rolling element in a state where the spacer is omitted, and then inserting the spacer between the bearing outer rings. As a result, the inner race can be formed directly on the hub wheel, and the number of parts can be reduced by omitting the inner ring.

(15) As a form of the drive wheel bearing unit having the above configuration, an inner ring in which one row of inner races is formed is fitted to the outer periphery of the hub wheel, and the remaining one row of inner races is attached to the outer peripheral surface of the hub wheel. Formed and configured inner member, a pair of inner rings fitted to the outer periphery of the hub wheel to configure the inner member, one row for the outer joint member of the hub wheel and the outboard side constant velocity universal joint An inner race is formed to form an inner member, and a plurality of inner races are formed directly on the outer peripheral surface of the hub wheel.

(16) If necessary, the inner ring and the hub ring can be positioned in the axial direction by swing caulking or a retaining ring.

  Conventionally, the pilot portion fitted to the inner periphery of the wheel is integrally formed with the hub wheel. By providing this pilot portion on a separate member other than the hub wheel, the shape of the hub wheel is simplified, so that the hub wheel can be manufactured by a low cost processing method such as forging instead of turning. In this case, the pilot portion can be formed in the brake rotor. In particular, if the brake rotor is manufactured by casting, the pilot portion can be formed at a low cost.

  According to the present invention, the male part and the female part can be firmly coupled and integrated, and at this time, it is not necessary to use a nut. In addition, this coupling can be performed by simply press-fitting one of the male part and the female part into the other. Therefore, the feature that the hub wheel and the outer joint member can be coupled at low cost and high strength with good workability is exhibited.

  Embodiments of a drive wheel bearing unit according to the present invention will be described in detail below.

  The drive wheel bearing unit shown in FIG. 1 includes a hub wheel 10, a bearing portion 20, and an outboard side constant velocity universal joint 30.

  The hub wheel 10 includes a wheel mounting flange 11 for mounting a wheel (not shown) on the outer peripheral surface thereof. A plurality of bolt holes 12 are formed in the circumferential direction of the wheel mounting flange 11, and hub bolts (not shown) for fixing the wheel and the disk are implanted in the bolt holes 12. An inner ring 28 is press-fitted into the small-diameter step 13 formed on the outer peripheral surface of the hub ring 10 with an appropriate tightening allowance. A retaining ring 29 is interposed between the inner circumferential surface of the inner ring 28 and the outer circumferential surface of the small diameter step portion 13, and the inner ring 28 and the hub wheel 10 are positioned in the axial direction by the retaining ring 29. The hub wheel 10 is manufactured by turning or forging.

  The bearing portion 20 has a double-row angular ball bearing structure arranged on the back surface, a double-row inner race 21 and an outer race 22, a rolling element 23 disposed between the inner race 21 and the outer race 22 facing each other, and an outboard side ( The holder 24 holds the rolling element row on the left side of the drawing and the rolling element row on the inboard side (right side of the drawing) at equal intervals in the circumferential direction. In the illustrated example, the inner race 21 on the outboard side is formed on the outer peripheral surface of the hub wheel 10, and the inner race 21 on the inboard side is formed on the outer peripheral surface of the inner ring 28. In this case, the hub wheel 10 and the inner ring 28 constitute an inner member 25 having a double row inner race.

  The outer race 22 is formed on the inner peripheral surface of the ring-shaped integrated outer member 26. The outer peripheral surface 26a of the outer member 26 is a cylindrical surface having a uniform diameter as a whole except for the retaining ring groove 26b. Unlike the conventional outer member, the flange (26c: refer FIGS. 11-13) for attaching to the knuckle member 6 is not provided. Seals 27 a and 27 b are press-fitted and fixed to the inner peripheral surfaces of both ends in the axial direction of the outer member 26.

  The seal 27a on the outboard side has a configuration in which a core metal is covered with an elastic material such as rubber and a plurality of (for example, three) seal lips are formed on the inner diameter side, and the core metal is attached to the inner peripheral surface of the outer member 26. The outer member 26 is fixed by press-fitting. The seal lip is in contact with the outer peripheral surface of the hub wheel 10 and the inboard side end surface of the flange portion 11.

  The inboard-side seal 27b is called a cassette seal, and has a configuration in which a plurality of (for example, three) seal lips formed on the inner diameter side of the core metal are brought into contact with a slinger having an inverted L-shaped cross section. The seal 27b is fixed to the opening by pressing the cored bar into the inner peripheral surface of the outer member 26 and pressing the slinger into the outer peripheral surface of the inner ring 28. Both ends of the bearing portion 20 are sealed by the seals 27a and 27b to prevent leakage of grease filled in the inside and intrusion of water and foreign matters from the outside.

  In the illustrated bearing portion 20, a ball is illustrated as the rolling element 23, but a tapered roller can be used as the rolling element 23 when the vehicle weight increases.

  The outboard-side constant velocity universal joint 30 is provided at one end of the intermediate shaft 2 on the outboard side, and has an outer joint member 31 having a track groove formed on the inner peripheral surface, and a track facing the track groove of the outer joint member 31. An inner joint member 32 having a groove formed on the outer peripheral surface, a torque transmission ball 33 incorporated between a track groove of the outer joint member 31 and a track groove of the inner joint member 32, and the outer joint member 31 and the inner joint member. And a cage 34 that is interposed between them and holds the torque transmission balls 33 at equal intervals in the circumferential direction. The inner joint member 32 is coupled to the shaft end on the outboard side of the intermediate shaft 2 inserted in the inner periphery thereof via a serration 35.

  The outer joint member 31 is manufactured by forging, for example, and includes a mouth portion 31a that houses the inner joint member 32, the cage 34, and the torque transmission ball 33, and a solid stem portion 31b that extends integrally from the mouth portion 31a in the axial direction. Have A large-diameter open end and a small-diameter open end of a bellows-shaped boot 37 are fixed to the outer peripheral surface of the mouth portion 31a and the outer peripheral surface of the intermediate shaft 2 via a boot band 36, respectively. Thus, by covering the space between the outer joint member 31 and the intermediate shaft 2 with the boot 37, it is possible to prevent a situation where grease leaks to the outside or foreign matters such as water and dust enter the joint. is doing.

  The stem portion 31b of the outer joint member 31 is plastically coupled to the hub wheel 10 by the method described below. When the hub wheel 10 and the outer joint member 13 are plastically coupled, the shoulder surface 38 of the outer joint member 31 is brought into contact with the end surface of the inner ring 28 on the inboard side, and the end surface of the inner ring 28 on the outboard side is also the hub wheel 10. , The distance between the double-row inner races 21 is maintained at a specified size, and a preload (preliminary preload) is applied.

  The plastic coupling between the hub wheel 10 and the outer joint member 31 is such that a male part 51 is formed on one of the members, and a male part 51 and a deformed female part 52 are formed on the other member. This is done by press-fitting 52 together. FIG. 1 illustrates a case where the male part 51 is formed on the stem part 31 b of the outer joint member 31 and the female part 52 is also formed on the inboard side end part of the hub wheel 10. One of the male part 51 and the female part 52 is formed in a perfect circle shape in cross section, and the other is formed in a non-circular shape in cross section. FIG. 7A illustrates, as an example, a case where the male part 51 is formed in a tooth-shaped surface such as serration and the female part 52 is formed in a cylindrical surface shape. The male part 51 having a non-circular cross section can be formed efficiently and accurately by forging or rolling.

  In addition, as the shape of the male part 51, a rectangular tube surface can be adopted as shown in FIG. Regardless of the shape, the inner diameter dimension Df of the female part 52 having a perfectly circular cross section is larger than the diameter of the circle A inscribed in the cross-sectional outline of the male part 51 and smaller than the diameter of the circumscribed circle B.

  By press-fitting the male part 51 having the above shape into the inner periphery of the female part 52, plastic flow is generated in the joint part, the female part follows the male part, and the shape of the male part is transferred to the female part. In addition, all or part of the gap between the two is satisfied. Thereby, the hub wheel 10 and the outer joint member 31 are plastically coupled and integrated.

  As shown in FIG. 9, after press-fitting, if the flange portion 58 is formed by caulking the outer peripheral portion (shown by a broken line) of the solid shaft end of the stem portion 31b with a caulking tool 59, the hub wheel 10 is prevented from coming off. The effect is further enhanced. If sufficient bonding strength can be obtained only by press-fitting, this caulking step can be omitted.

In this connection structure, it is desirable that the male part 51 having a tooth profile surface is heat-treated in advance so that the surface layer H is harder than the female part 52 as shown in FIG. Thereby, the deformation of the male part 51 due to the press-fitting is suppressed, and the male part 51 easily bites into the female part 52, so that the coupling strength can be further increased. When the caulking process shown in FIG. 9 is performed, the shaft end portion of the stem portion 31b to be plastically deformed by caulking is not quenched, and the flange portion 58 can be easily formed. As a heat treatment method for the male part 51, induction hardening in which the quenching range and the quenching depth are easily controlled is desirable. The female part 52 is basically a raw material not subjected to heat treatment, but may be subjected to heat treatment as long as the surface hardness of the male part 51 is not exceeded.

  In the above description, the case where the male portion 51 having the tooth profile surface is formed on the stem portion 31b of the outer joint member 31 and the female portion 52 is formed on the hub wheel 10 is exemplified. On the contrary, the male part 51 having a tooth profile surface may be formed on the inner periphery of the hub wheel 10, and the female part 52 may be formed on the stem part 31 b of the outer joint member 31. The male part 51 on the inner periphery of the hub wheel 52 can be formed by broaching, for example. Also in this case, the male part 51 is formed with higher hardness than the female part 52.

  By the way, when the male part 51 is press-fitted into the female part 52, the hub wheel 10 is slightly deformed in the diameter increasing direction, and the influence may be exerted on the inner race 21. In order to avoid such a situation as much as possible, it is preferable to arrange the press-fitting portions of both on the axial center line O of the rolling elements 23 on the inboard side and the outboard side as shown in FIG.

  In the bearing unit shown in FIG. 1, the outer peripheral surface 26 a of the outer member 26 is fitted and incorporated into the inner peripheral surface 6 a of the knuckle member 6 on the vehicle body side. The fitting integration means that the integration of both is completed by fitting the outer member 26 to the knuckle member 6. This incorporation can be performed, for example, by pressing the cylindrical outer peripheral surface 26a of the outer member 26 into the cylindrical inner peripheral surface 6a of the knuckle member 6 from the outboard side.

  If necessary, the inboard side end of the inner peripheral surface 6a of the knuckle member 6 is provided with a convex portion 6b that engages with the end surface of the outer member 26 in the axial direction. Alternatively, the retaining ring 53 is interposed between the outer peripheral surface of the outer member 26 and the inner peripheral surface 6 a of the knuckle member 6. By using these convex portions 6b and retaining rings 53, the effect of preventing the outer member 26 and the knuckle member 6 from coming off is further enhanced. As shown in FIG. 1, when both the retaining ring 53 and the convex portion 6b are provided, the inboard side end surface of the outer member 26 press-fitted from the outboard side contacts the convex portion 6b, and at the same time, the knuckle member 6 The retaining ring groove 6c formed on the inner circumferential surface 6a and the retaining ring groove 26b formed on the outer circumferential surface 26a of the outer member 26 face each other, and the retaining ring 53 accommodated in the retaining ring groove 26b of the outer member 26 is elastic. And is engaged with both the knuckle member 6 and the outer member 26 in the axial direction.

  When a sufficient fixing force can be obtained only by press-fitting, either one or both of the convex portion 6b and the retaining ring 53 can be omitted. 30 shows a case where the convex portion 6b is omitted, and FIG. 31 shows a case where the retaining ring 58 is omitted (as shown in FIG. 31, a retaining ring 29 between the hub wheel 10 and the inner ring 28 is also attached. Can be omitted).

  When the retaining ring 53 is used, it is desirable to dispose the retaining ring 53 on the outboard side as much as possible. Specifically, as shown in FIG. 1, a retaining ring 53 is disposed on the outboard side with respect to the axial center line O between the inboard side rolling element 23 and the outboard side rolling element 23. Is desirable. Thus, when the outer member 26 is press-fitted, the sliding distance of the retaining ring 53 relative to the knuckle member inner circumferential surface 6 a can be shortened, so that the knuckle member inner circumferential surface 6 a can be prevented from being damaged by dragging the retaining ring 53. it can.

  Thus, by providing a press-fit surface on the outer peripheral surface 26a of the outer member 26 and press-fitting and fixing the outer member 26 to the inner periphery of the knuckle member 6, the outer member with a flange can be attached to the knuckle member as in the prior art. Compared with the case of bolting to a plurality of locations, the bolt fastening operation can be omitted, and the number of parts and the number of work steps can be reduced accordingly, thereby reducing the cost.

  In addition, by pressing the outer member 26 into the knuckle member 6, radial contraction force acts on the outer member 26 after press-fitting, and the bearing gap is reduced by the contraction force. Accordingly, if the press-fitting allowance is appropriately set in consideration of the preliminary preload amount, an appropriate amount of negative gap (for example, 0 to 100 μm, preferably 0 to 30 μm) can be obtained after press-fitting. In this case, since the preload application work by tightening the nut is not necessary, the assembly workability of the bearing unit can be further improved. If the positive clearance is larger than 0, the bearing rigidity is insufficient and the durability is lowered, and if the negative clearance exceeds 100 μm, the preload is excessively increased, causing abnormal heat generation. Is a problem.

  In such fitting and incorporation, the maximum outer diameter D1 of the outboard side constant velocity universal joint 30 is made smaller than the minimum inner diameter Dn of the knuckle member 6 (D1 <Dn). As a result, first, the outboard side constant velocity universal joint 30 is inserted into the inner periphery of the knuckle member 6, and then the outer member 26 of the bearing portion 20 is press-fitted into the inner periphery of the knuckle member 6. The bearing portion 20 and the outboard side constant velocity universal joint 30 can be assembled to the vehicle in a state of being assembled in advance. At the time of this assembly, the pushing direction of the assembly is constant, so that the workability at the time of assembly is also good.

  Here, the “minimum inner diameter dimension Dn” of the knuckle member 6 means the inner diameter dimension of the portion of the knuckle member 6 that is present on the innermost diameter side. As in the embodiment shown in FIG. 1, when the convex portion 6 b is provided on the inner peripheral surface of the knuckle member 6, the inner diameter dimension of the convex portion 6 b becomes the “minimum inner diameter dimension”. When the convex portion 6b is omitted as shown in FIG. 30, the inner peripheral surface 6a of the knuckle member 6 has a “minimum inner diameter dimension”.

  Further, the “maximum outer diameter dimension D1” of the outboard side constant velocity universal joint refers to the outer diameter dimension of the portion existing on the outermost diameter side in a state including accessories such as the boot 37 and the boot band 36. For example, in the outboard-side constant velocity universal joint 30 shown in FIG. 1, the outer diameter of the boot maximum diameter portion 37 a is the maximum outer diameter D1 of the outboard-side constant velocity universal joint 30.

  In addition, as shown in FIG. 4, if the maximum outer diameter D2 of the inboard constant velocity universal joint 40 of the drive shaft 1 is made smaller than the minimum inner diameter Dn of the knuckle member 6 (D2 <Dn), the drive shaft 1 Even in a state in which the hub wheel 10 and the bearing portion 20 are assembled in advance (hereinafter referred to as a drive shaft assembly), it can be assembled to the vehicle. That is, the drive shaft assembly is sequentially inserted into the inner periphery of the knuckle member 6 in the order of the inboard side constant velocity universal joint 40, the intermediate shaft 2, and the outboard side constant velocity universal joint 30, and then the outer peripheral surface 26a of the outer member 26. Is pressed into the inner peripheral surface of the knuckle member 6 to complete the assembly to the vehicle. Thereby, the work man-hour at the assembly work site can be reduced, and workability is enhanced. In this case, it is not necessary to turn the knuckle member 6 as in the conventional process, so that the work space is minimized. The maximum outer diameter D2 of the inboard side constant velocity universal joint 40 is the same as that of the outboard side constant velocity universal joint 30, and the inboard side in a state including accessories such as the boot 37 and the boot band 36. This means the maximum outer diameter of the quick universal joint 40.

  As shown in FIG. 5, a gap 55 is formed between the outer diameter side region of the seal 27 in the outer peripheral surface 26a of the outer member 26 and the inner peripheral surface 6a of the knuckle member 6 facing the outer peripheral surface 26a. desirable. As shown in the figure, the gap 55 can also be formed by forming a mussel portion 56 on the outer peripheral surface 26 a of the outer member 26, or by forming a mushy portion (not shown) on the inner peripheral surface 6 b of the knuckle member 6. is there. Note that the press-fitting allowance between the outer member 26 and the knuckle member only needs to be secured in the outer diameter side region of the outer race 22, and therefore, as shown by the broken line in FIG. A nuisance part 57 may be formed in the region. Thereby, since the press-fitting area is reduced, the workability at the time of press-fitting can be further increased, and on the other hand, a predetermined preload can be applied to the bearing portion 20 at the time of press-fitting.

  When the outer member 26 is press-fitted, if the press-fitting allowance is set uniformly on the outer diameter side of each outer race 22, the amount of preload applied to the bearing portion 20 can be stabilized.

  As shown in FIG. 6, the outboard wall surface 6c1 of the retaining ring groove 6c formed in the inner peripheral surface 6a of the knuckle member 6 can be formed in a tapered surface shape. In this case, if the outer member 26 is pulled out to the outboard side with a predetermined force as indicated by an arrow, the retaining ring 53 is reduced in diameter by the guide of the tapered surface 6c1, so that the drive shaft assembly is separated from the knuckle member 6. This makes it possible to improve the workability of the assembly inspection and replacement work. It is desirable to set the angle θ of the tapered surface 6c1 in the range of 15 ° to 30 °, in order to achieve both the retaining effect when fitting and mounting and the workability during replacement.

  2 and 3 show other configurations of the drive wheel bearing unit. Among these, in the bearing unit shown in FIG. 2, the double row inner races 21 of the bearing portion 20 are all formed on the outer peripheral surface of the integral inner ring 28 press-fitted into the outer periphery of the hub wheel 10. In this case, the inner ring 28 constitutes the inner member 25 having the double-row inner race 21. FIG. 3 shows an example in which the integral inner ring 28 shown in FIG. 2 is divided into two in the axial direction and press-fitted into the outer peripheral surface of the hub wheel 10 to form inner races 21 on the outer peripheral surfaces of the two inner rings 28a and 28b. It is. In this configuration, the two inner rings 28 a and 28 b constitute the inner member 25 having the double-row inner race 21. In any of the bearing units shown in FIGS. 2 and 3, both end openings of the bearing portion 20 are sealed with cassette seals 27a and 27b.

  Except for the points described above, the configuration of the bearing unit shown in FIG. 2 and FIG. 3 is the same as the configuration of the bearing unit shown in FIG. The description of the overlapping part is omitted.

  In FIGS. 1 to 3, the hub wheel 10 and the inner rings 28, 28 a, 28 b are positioned by the retaining ring 29, but they can also be positioned by swing caulking instead. FIG. 10 shows an example of this, by extending the cylindrical shaft end of the small-diameter step 13 of the hub wheel 10 over the inboard side end surface of the inner ring 28 and swinging the crimping tool on the inner diameter side of the protruding portion. The flange 17 is formed by plastically deforming the protruding portion toward the outer diameter side. The flange 17 is in close contact with the end face on the inboard side of the inner ring 28. In the bearing unit shown in FIGS. 2 and 3 as well, the hub ring 10 and the inner rings 28, 28 a, 28 b can be positioned in the axial direction by similarly performing rocking caulking to form the flange 17.

  In addition, as a drive wheel bearing unit, as shown in FIG. 14, an inner race 21 on the outboard side is formed on the outer peripheral surface of the hub wheel 10, and the inner race 21 on the inboard side is formed on the outer periphery of the outer joint member 31. A type formed on the surface can also be used. Also in this bearing unit, the hub wheel 10 and the outer joint member 31 are plastically coupled by press-fitting the male part 51 into the female part 52 and further by caulking as shown in FIG. In this case, for example, a male portion 51 having a tooth-shaped surface is formed on the outer peripheral surface of the solid end portion 16 on the inboard side of the hub wheel 10, and a female portion is formed on the inner peripheral surface of the stem portion 31 b facing this. 52 is formed. The end surface of the outer joint member 31 is in contact with the hub wheel 10 in the axial direction, whereby the dimension between the double-row inner races 21 is defined, and a preliminary preload is applied to the bearing portion 20. In this case, the hub wheel 10 and the outer joint member 31 constitute the inner member 25 having the double-row inner race 21.

  FIG. 14 illustrates the case where the hub wheel 10 is fitted to the inner periphery of the hollow stem portion 31b and the both are plastically coupled. On the contrary, on the inner periphery of the hollow hub wheel 10 is illustrated. The solid stem portion 31b can be fitted to be plastically coupled to each other (see FIG. 16).

  1 to 3 exemplify a case where the outer peripheral surface 26a of the outer member 26 is formed into a cylindrical surface over the entire surface, and this outer peripheral surface is fitted and incorporated into the inner peripheral surface 6a of the knuckle member 6. As shown in FIG. 11, a flange 26 c may be formed on the outer peripheral surface 26 a of the outer member 26, and the flange 26 c may be bolted to the knuckle member 6. In this case, the outer peripheral surface 26a of the outer member 26 and the inner peripheral surface 6a of the knuckle member 6 are fitted with a clearance fit. FIG. 11 is equivalent to FIG. 1 in which the inner member 25 is formed by the hub ring 10 and the inner ring 28, but a similar configuration is a view in which the inner member 25 is formed by the integrated inner ring 28 as shown in FIG. As shown in FIG. 13, the present invention can also be applied to the equivalent of FIG. 3 and the equivalent of FIG. 3 in which the inner member 25 is formed by the divided inner rings 28a and 28b.

  In each of the embodiments described above, the bearing portion 20 in which the rolling element 23 is held by the cage 24 is illustrated, but a total rolling element type that does not use the cage as shown in FIG. 15 can also be adopted. In the case of the total rolling element type, the number of rolling elements that can be incorporated is increased as compared with the case of using a cage, so that the load load of each rolling element can be reduced. Accordingly, the life of the bearing unit can be improved even under high load conditions. The total rolling element type can be used only on the high load side when there is a difference in load load between the inboard side rolling element row and the outboard side rolling element row. Of course, when both rolling element rows have the same load condition, both can be made into a total rolling element type. Usually, since the moment load on the inboard side becomes large, the rolling element row on the inboard side is made the total rolling element type.

  In the case of the total rolling element type, if the circumferential gap between the rolling elements is too large, the rolling elements may collide violently and generate sound and heat generation. Is smaller than the diameter Db of the rolling element 23 (particularly, when a ball is used as the rolling element 23, the total clearance S is set to about 40% or less of the ball diameter).

  Also in the bearing type using the cage 24, as shown in FIG. 16, there is a difference between the PCD (P1) of the rolling body row on the outboard side and the PCD (P2) of the rolling body row on the inboard side. As a result, an effect of increasing rigidity and extending the service life can be expected. This is because if one PCD is increased, the bearing span (interval between the line of action in the direction of action of the force applied to both race surfaces and the axis) is increased without increasing the axial dimension of the bearing unit. The reason is that the number of rolling elements that can be incorporated and the number of rolling elements that can be incorporated increase. FIG. 16 illustrates the case where the PCD (P2) of the rolling element row on the inboard side is increased. However, as shown in FIG. 17, the PCD (P1) of the rolling element row on the outboard side is increased as shown in FIG. May be. Further, by making the inboard side retainer 24 and the outboard side retainer 24 different from each other, the same effect can be obtained even if more rolling elements are incorporated in the retainer 24 on either side. It is done. Furthermore, as shown in FIGS. 18A and 18B, the same effect can be obtained even if the diameter of the rolling element 23 on the inboard side is different from the diameter of the rolling element 23 on the outboard side.

  FIG. 19 shows another configuration of the drive wheel bearing unit.

  In this bearing unit, the outer member 26 includes a pair of bearing outer rings 261 and 262 and a ring-shaped spacer 263 disposed between the bearing outer rings 261 and 262. Outer races 22 are formed on the inner peripheral surfaces of both bearing outer rings 261 and 262, respectively. Double rows of inner races 21 are directly formed on the outer peripheral surface of the hub wheel 10. In the drawing, the end surface on the inboard side of the hub wheel 10 is brought into contact with the shoulder surface 38 of the outer joint member 31, but a gap may be interposed therebetween.

  Out of the seals 27 that seal the opening portions at both ends of the bearing portion 20, the seal 27 a on the outboard side is a core metal in which a plurality of (for example, two) seal lips are formed by covering the outer diameter end with an elastic material such as rubber. 271 and a slinger 272 in contact with the seal lip. The metal core 271 is press-fitted and fixed to the outer peripheral surface of the hub wheel 10, and the slinger 272 is press-fitted and fixed to the inner peripheral surface of the bearing outer ring 262 on the outboard side. The end on the outboard side of the slinger 272 is adjacent to the inboard side end surface of the flange 11 to form a labyrinth seal.

  The outer peripheral surfaces of the bearing outer rings 261 and 262 and the spacer 263 are all cylindrical surfaces. Each of the bearing outer rings 261, 262 has a cylindrical outer peripheral surface and is press-fitted into the inner peripheral surface 6a of the knuckle member 6. The outer diameter of the spacer 263 is the outer diameter of the bearing outer rings 261, 262. There is a slight gap between the inner peripheral surface of the knuckle member 6 and slightly smaller than the size. The spacer 263 is divided into two in the circumferential direction as shown in FIG.

  The bearing outer ring 262 on the outboard side is positioned by a retaining ring 53. As the retaining ring 53, as shown in FIG. 20, a C-type having an operation portion 53a extending to the outer diameter side at both ends in the circumferential direction can be used. The retaining ring 53 is fitted into a retaining ring groove 6 c formed on the inner peripheral surface of the knuckle member 6, and the operation portion 53 a is accommodated in the axial notch 6 d formed on the knuckle member 6, so that the retaining ring 53 is supported by the bearing outer ring. The outer member is positioned by engaging with the end face on the outboard side of 262.

  The bearing unit is assembled in the following procedure.

  First, as shown in FIG. 22, a metal core 271 of the seal 27 a on the outboard side is press-fitted and fixed to the outer periphery of the hub wheel 10.

  Next, as shown in FIG. 23, the rolling elements 23 are assembled on the outer periphery of the hub wheel 10 and accommodated in the inner race 21. At this time, the rolling element 23 is incorporated in the outer periphery of the hub wheel 10 in a state of being accommodated in the pocket of the cage 24 in advance. Next, the bearing outer ring 262 on the outboard side is inserted into the outer periphery of the hub wheel 10. At this time, the slinger 272 is press-fitted into the inner peripheral surface of the bearing outer ring 262 in advance. When the bearing outer ring 262 is pushed to the outboard side, the seal lip formed on the cored bar 271 contacts the inner peripheral surface of the slinger 272, and the seal 27b is formed. Further, the rolling element 23 is accommodated in the outer race 22 of the bearing outer ring 262.

  Next, as shown in FIG. 24, the bearing outer ring 261 on the inboard side is inserted into the outer periphery of the hub wheel 10. At this time, the bearing outer ring 261 is positioned on the outboard side from the specified position by contacting the bearing outer ring 262 on the outboard side or the like, so that the inboard side end portion of the bearing outer ring 261 and the hub wheel 10 are interposed. Since a gap δ larger than the ball diameter D is formed, the rolling element 23 is inserted into the space between the bearing outer ring 261 and the hub ring 10 from this gap δ. When the prescribed number of rolling elements 23 has been inserted, the retainer 24 is pushed through the opening on the inboard side to accommodate the rolling elements 23 in the pockets, and the rolling elements 23 are held at equal intervals in the circumferential direction.

  Next, as shown in FIG. 25, a gap is formed between the bearing outer rings 261 and 262, and the split spacer 263 is inserted so that the hub ring 10 is sandwiched between the gaps. As a result, the bearing outer ring 261 on the inboard side is disposed at the specified position, and the rolling element 23 on the inboard side is accommodated in the inner race 21 and the outer race 22 with a predetermined contact angle.

  Thereafter, as shown in FIG. 26, a cassette seal is press-fitted into the opening between the inboard-side bearing outer ring 261 and the hub wheel 10 to form a seal 27b.

  After the above assembly is completed, for example, the male part 51 having a tooth profile surface formed on the stem part 31b of the outer joint member 31 is press-fitted into the female part 52 formed on the inner peripheral surface of the hub wheel 10, and further shown in FIG. By performing the caulking shown, the hub wheel 10 and the outer joint member 31 are plastically coupled. Thereafter, the inboard side constant velocity universal joint 40, the intermediate shaft 2, and the outboard side constant velocity universal joint 30 are inserted in this order into the inner periphery of the knuckle member 6, and finally the outer ring member 53 is expanded while the diameter of the retaining ring 53 is increased. 26 is press-fitted, and the bearing outer ring 261 on the inboard side is brought into contact with the convex portion 6b. Thereafter, the retaining ring 53 is elastically reduced in diameter and engaged with the end face of the bearing outer ring 262 to complete the assembly of the drive shaft assembly.

  With the above configuration, since the insertable spacer 263 is disposed between the pair of bearing outer rings 261, 262, even when the inner race 21 is formed directly on the hub wheel 10, double rows The rolling element 23 can be incorporated in the space between the outer member 26 and the hub wheel 10. Accordingly, the inner rings 28, 28a and 28b shown in FIGS. 1 to 3 are not necessary, and the cost can be reduced by reducing the number of parts.

  In this embodiment, in addition to using a retaining ring 53 that engages with the end face of the bearing outer ring 262 as shown in FIG. 19, the bearing outer ring 262 on the outboard side is also shown in FIGS. A retaining ring 53 interposed between the outer peripheral surface and the inner peripheral surface 6a of the knuckle member 6 can also be used. If there is no particular problem in assemblability, the seal 27a on the outboard side has a seal lip at the inner diameter end of the cored bar as in the seal 27a shown in FIG. It is also possible to use a type that is press-fitted into the inner peripheral surface of 26.

  FIG. 27 shows another embodiment of the present invention. This bearing unit for a drive wheel is an example in which a cylindrical pilot portion 72 fitted to the inner periphery of the wheel 80 is provided on a member different from the hub wheel 10, for example, the brake rotor 70. The brake rotor 70 is disposed between the end face on the outboard side of the flange 11 of the hub wheel 10 and the wheel 80, and holes 71 for inserting hub bolts are formed at a plurality of locations in the circumferential direction.

  As shown in FIGS. 1 to 3, the pilot portion 72 is usually formed integrally with the end portion on the outboard side of the hub wheel 10, and thus the shape of the hub wheel 10 is complicated. Therefore, in practice, it is difficult to forge the hub wheel 10 and it is often a turning product. Further, the pilot portion 72 needs to be partially rust-proofed. From the above, the manufacturing cost of the hub wheel 10 tends to increase.

  On the other hand, if the pilot portion 72 of the hub wheel 10 is eliminated and is provided at, for example, the inner diameter end portion of the brake rotor 70 as shown in FIG. 27, the shape of the hub wheel 10 on the outboard side is simplified. Therefore, it becomes possible to forge-mold this, and the antirust coating process to the hub wheel 10 is also unnecessary. Therefore, the cost of the hub wheel 10 can be reduced, and a light weight design can be achieved. Since the brake rotor 70 is usually formed by casting, the brake rotor 70 having the pilot portion 72 can be manufactured at low cost.

  FIG. 27 shows a bearing unit corresponding to FIG. 1 in which the inner member 25 is formed by the hollow hub wheel 10 and the inner ring 28, but a similar configuration is shown in FIG. 2 in which the inner member 25 is formed by the integrated inner ring 28. An equivalent bearing unit (see FIG. 28) and a bearing unit equivalent to FIG. 3 (see FIG. 29) in which the inner member 25 is formed by the divided inner rings 28a and 28b can also be employed. In the bearing unit shown in FIGS. 28 to 29, the hub wheel 10 and the inner rings 28, 28a, and 28b are positioned by the flange 17 by diameter-enlarged caulking. As shown in FIGS. Positioning can also be performed with the retaining ring 29.

It is sectional drawing of the bearing unit for drive wheels. It is sectional drawing of the bearing unit for drive wheels. It is sectional drawing of the bearing unit for drive wheels. It is sectional drawing of a drive shaft. It is sectional drawing which expands and shows the press fit part of an outward member and a knuckle member. It is sectional drawing which expands and shows the press fit part of an outward member and a knuckle member. (A) The figure is sectional drawing of the male part in the coupling | bond part of a hub ring and an outer joint member, (b) Figure is sectional drawing of a female part similarly. It is sectional drawing which shows the other structural example of a male part. It is sectional drawing which shows the plastic coupling process of a hub ring and an outer joint member. It is sectional drawing of the wheel bearing unit for drive wheels. It is sectional drawing of the bearing unit for drive wheels. It is sectional drawing of the bearing unit for drive wheels. It is sectional drawing of the bearing unit for drive wheels. It is sectional drawing of the bearing unit for drive wheels. It is a front view showing a total rolling element type bearing structure. It is sectional drawing of the bearing unit for drive wheels which gave the difference to the rolling element PCD. It is a side view which illustrates schematically the rolling element which has different PCD. It is a side view which illustrates schematically the rolling element from which a diameter differs. It is sectional drawing of the bearing unit for drive wheels. It is sectional drawing of a retaining ring. It is sectional drawing of a spacer. It is sectional drawing which shows the assembly process of the bearing unit for drive wheels. It is sectional drawing which shows the assembly process of the bearing unit for drive wheels. It is sectional drawing which shows the assembly process of the bearing unit for drive wheels. It is sectional drawing which shows the assembly process of the bearing unit for drive wheels. It is sectional drawing which shows the assembly process of the bearing unit for drive wheels. It is sectional drawing of the bearing unit for drive wheels. It is sectional drawing of the bearing unit for drive wheels. It is sectional drawing of the bearing unit for drive wheels. It is sectional drawing which expands and shows the principal part of the bearing unit for drive wheels. It is sectional drawing which expands and shows the principal part of the bearing unit for drive wheels. It is sectional drawing which shows schematic structure around the suspension apparatus of a vehicle.

DESCRIPTION OF SYMBOLS 1 Drive shaft 2 Intermediate shaft 6 Knuckle member 6a Inner peripheral surface 6b Protruding part 6c Retaining ring groove 6c1 Tapered surface 10 Hub wheel 11 Flange 20 Bearing part 21 Inner race 22 Outer race 23 Rolling body 24 Cage 25 Inner member 26 Outer member 26a Outer peripheral surface 27a Seal 27b Seal 28 Inner ring 28a Inner ring 28b Inner ring 29 Retaining ring 30 Outboard side constant velocity universal joint 31 Outer joint member 31a Mouse part 31b Stem part 32 Inner joint member 33 Torque transmission ball 34 Cage 36 Boot band 37 Boot 38 Shoulder surface 39 Cap 40 Inboard side constant velocity universal joint 51 Male part 52 Female part 53 Retaining ring 56 Nusumi part 57 Nusumi part 70 Brake rotor 72 Pilot part 80 Wheel Dn Minimum inner diameter D1 of knuckle member Outboard side constant velocity universal joint Maximum outer diameter D2 Maximum outer diameter of the constant velocity universal joint on the board side O Axial centerline

Claims (27)

An inner member having an outer member having a plurality of outer races on the inner periphery, a hub wheel provided with a flange for mounting on a wheel, and having an inner race facing the outer race, and the outer race and inner race facing each other In a drive wheel bearing unit comprising a plurality of rows of rolling elements disposed between and an outboard constant velocity universal joint,
One of the outer joint members of the hub wheel and the outboard side constant velocity universal joint is provided with a male part having a tooth-shaped surface, the male part is provided on the other side, and the female part having a different cross-sectional shape from the male part Having a coupling portion formed by axially press-fitting into
The drive wheel bearing unit, wherein the coupling part is completed by biting into the female part of the male part accompanying the press-fitting.   The drive wheel bearing unit according to claim 1, wherein the male part has a higher hardness than the female part.   The drive wheel according to claim 1 or 2, wherein a stem portion is provided on an outer joint member of the outboard side constant velocity universal joint, and an axial length of a joint portion between the male portion and the female portion is equal to or less than a radial dimension of the stem portion. Bearing unit.   The outer peripheral surface of the outer member is fitted to the inner peripheral surface of the knuckle member on the vehicle body side, and the maximum outer diameter dimension of the outboard-side constant velocity universal joint is smaller than the minimum inner diameter dimension of the knuckle member. 2. A drive wheel bearing unit according to item 1. The outer peripheral surface of the outer member is fitted to the inner peripheral surface of the knuckle member on the vehicle body side, and the inboard side constant velocity universal joint is connected to the outboard side constant velocity universal joint via the intermediate shaft. driving wheel bearing unit according to a small claims 1-3 any one than the minimum inner diameter dimension of the maximum outer diameter dimension knuckle member of the universal joint. The bearing unit for driving wheels according to claim 4 or 5 , wherein the outer peripheral surface of the outer member is cylindrical, and the outer peripheral surface is press-fitted into the inner peripheral surface of the knuckle member. 7. The drive wheel bearing unit according to claim 6 , wherein the outer member is prevented from coming off from the knuckle member by a retaining ring. The bearing unit for driving wheels according to claim 7 , wherein an outboard side of a retaining ring groove provided in the knuckle member is formed into a tapered surface. The bearing unit for drive wheels of Claim 7 or 8 which has arrange | positioned the said retaining ring to the outboard side rather than the axial direction centerline of the rolling element of the inboard side and the rolling element of the outboard side. The drive wheel according to any one of claims 6 to 9 , wherein a seal member is fixed to the inner peripheral surface of the outer member, and a sumi portion is provided in an outer diameter side region of the seal member on the outer peripheral surface of the outer member. Bearing unit. The bearing unit for drive wheels according to any one of claims 6 to 10 , wherein a Nusumi portion is provided in an outer diameter side region between the outer race on the inboard side and the outer race on the outboard side of the outer peripheral surface of the outer member. The drive wheel bearing unit according to any one of claims 1 to 5, wherein a flange for attaching to the knuckle member is formed on the outer peripheral surface of the outer member. Driving wheel bearing unit according to any one of claims 1 to 12 in which the bearing gap is set to a negative gap. The drive wheel bearing unit according to any one of claims 1 to 13 , wherein PCDs of the inboard side rolling element and the outboard side rolling element are different from each other. The drive wheel bearing unit according to any one of claims 1 to 14, wherein the inboard side rolling element and the outboard side rolling element have different diameters. The drive wheel bearing unit according to any one of claims 1 to 15, wherein the number of rolling elements on the inboard side and the number of rolling elements on the outboard side are different from each other. The drive wheel bearing unit according to any one of claims 1 to 16 , wherein at least one of the rolling element rows is of a total rolling element type. The bearing unit for driving wheels according to any one of claims 1 to 17 , wherein a male part is press-fitted into a female part on an axial center line of an inboard side rolling element and an outboard side rolling element. Outboard side constant velocity universal joint, the outer joint member, the inner joint member, to any one of claims 1 to 18 and a torque transmitting balls is interposed between the outer joint member and the inner joint member The bearing unit for a drive wheel as described. The drive wheel bearing unit according to any one of claims 1 to 11 , wherein the outer member includes a pair of bearing outer rings each having an outer race, and a spacer interposed between the bearing outer rings. 20. An inner member is formed by fitting an inner ring formed with one row of inner races to the outer periphery of the hub wheel and forming the remaining one row of inner races on the outer peripheral surface of the hub wheel. A bearing unit for a drive wheel described in 1. The bearing unit for driving wheels according to any one of claims 1 to 19 , wherein a pair of inner rings are fitted to an outer periphery of the hub ring to constitute an inner member. 21. The drive wheel bearing unit according to claim 20, wherein a plurality of inner races are formed directly on the outer peripheral surface of the hub wheel. The bearing unit for a drive wheel according to any one of claims 1 to 19 , wherein an inner race is formed by forming an inner race on each of the outer joint members of the hub wheel and the outboard side constant velocity universal joint.   The drive wheel bearing unit according to claim 21 or 22, wherein the inner ring and the hub ring are axially positioned by swing caulking.   The drive wheel bearing unit according to claim 21 or 22, wherein the inner ring and the hub ring are axially positioned by a retaining ring. An inner member having an outer member having a plurality of outer races on the inner periphery, a hub wheel provided with a flange for mounting on a wheel, and having an inner race facing the outer race, and the outer race and inner race facing each other In a drive wheel bearing unit comprising a plurality of rows of rolling elements disposed between and an outboard constant velocity universal joint,
One of the outer joint members of the hub wheel and the outboard side constant velocity universal joint is provided with a male part having a tooth-shaped surface, the male part is provided on the other side, and the female part having a different cross-sectional shape from the male part Having a coupling portion formed by axially press-fitting into
The coupling part is completed by biting into the female part of the male part accompanying the press-fitting,
A drive wheel bearing unit in which a stem portion is provided on an outer joint member of an outboard side constant velocity universal joint, and an axial length of a joint portion between the male portion and the female portion is set to be equal to or less than a radial dimension of the stem portion.

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