JP2008001238A - Bearing unit for driving wheel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bearing for a driving wheel capable of securely unite a hub wheel and an outside joint member without using a nut, and preventing influences to an inner race even when the hub wheel is slightly deformed due to pressing-in. <P>SOLUTION: Of the hub wheel 10 and the outside joint member 31, a male portion 61 is provided at a stem portion 13b of the outside joint member 31, and a female portion 52 having a different shape from the male portion 51 is formed on an inner peripheral surface of the hub wheel 10. By pressing the male portion 51 into the female portion 52, plastic flow is generated at a joint portion, filling a clearance between the hub wheel 10 and the outside joint member 31, thereby plastically uniting the both. A press-in portion of the male portion 51 and the female portion 52 is arranged on an axial center line of a rolling element 23 on an in-board side and a rolling element 23 on an out-board side. <P>COPYRIGHT: (C)2008,JPO&INPIT

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. 16, the drive shaft 1 that transmits the power from the engine to the drive wheel 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 present invention can connect the hub wheel and the outer joint member with high strength without using a nut, and even if the hub wheel is slightly deformed by press-fitting, the influence on the inner race is affected. Provided is a bearing unit for a drive wheel that can prevent the above.

  In order to achieve the above object, the present invention provides an outer member having a plurality of outer races on the inner periphery, an inner member having a plurality of inner races facing the outer races, and an outer member and an inner race facing each other. In a drive wheel bearing unit comprising a plurality of rows of rolling elements arranged in a wheel, a hub wheel attached to the wheel, and an outboard side constant velocity universal joint, the outer joint member of the hub wheel and the outboard side constant velocity universal joint Of these, the male part provided on either side is provided on the other side, and the male part and the female part deformed are press-fitted to plastically connect the hub wheel and the outer joint member, and The press-fitting part was arranged on the axial center line of the rolling element on the inboard side and the rolling element on the outboard side.

  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.

  The male part is press-fitted into the female part on the axial center line of the inboard-side rolling element and the outboard-side rolling element, so even if the hub wheel is slightly deformed by the press-fitting, the effect will affect the inner race. Can be prevented.

  In the above configuration, the outer peripheral surface of the outer member is fitted and assembled into the inner peripheral surface of the knuckle member on the vehicle body side, and the maximum outer diameter dimension of the constant velocity universal joint on the outboard side is larger than the minimum inner diameter dimension 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 member of the constant velocity universal joint on the outboard side and the hub wheel are coupled to each other, and the outer member is assembled and fitted into the knuckle member from the outboard side, thereby fixing the bearing unit to the knuckle member. It becomes possible. Such an operation can be performed simply by pushing the bearing unit in the direction of the axle, and there is basically no need to bolt the outer member to the knuckle member. Therefore, the work of assembling the bearing unit to the vehicle can be simplified. When the above effects are not particularly required, a flange for attaching to the wheel 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.

  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. In addition, even when the hub wheel is slightly deformed by press fitting, it is possible to prevent the influence from affecting the inner race and to exhibit a stable function as a drive wheel bearing unit.

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

  The drive wheel bearing unit of the first embodiment 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 its outer peripheral surface. A plurality of female screws 12 are formed in the circumferential direction of the wheel mounting flange 11, and wheel bolts (not shown) for fixing a wheel and a disk are fitted to the female screws 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 positioning of the inner ring 28 and the hub wheel 10 in the axial direction is performed by the retaining ring 29. The hub wheel 10 is manufactured by turning or forging.

  The bearing portion 10 has a double-row angular ball bearing structure arranged on the back surface, and includes 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 a conventional outer member, a flange (26c: refer to the fourth embodiment shown in FIG. 9, the fifth embodiment shown in FIG. 10, and the sixth embodiment shown in FIG. 11) for attaching to the knuckle member 6 is provided. It is not done. 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 outboard-side seal 27a 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 formed on 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 31 are plastically coupled, the shoulder surface 38 of the outer joint member 31 is brought into contact with the end surface on the inboard side of the inner ring 28, 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. As an example, FIG. 5A illustrates a case where the male part 51 is formed in a tooth-shaped surface such as a serration and the female part 51 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, and all or part of the gap between the two parts is satisfied. Thereby, the hub wheel 10 and the outer joint member 31 are plastically coupled and integrated.

  As shown in FIG. 7, if the flange portion 58 is formed by crimping the outer peripheral portion (shown by a broken line) of the solid shaft end of the stem portion 31 b with a crimping tool 59 after press-fitting, the hub wheel 10 is prevented from coming off. The effect is further increased. If sufficient bonding strength can be obtained only by press-fitting, this caulking step can be omitted.

  In this connection structure, it is desirable to heat-treat the male part 51 having a non-circular cross section 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. 7 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 part 51 is formed in a non-circular shape in cross section and the female part 52 is formed in a circular shape in cross section has been exemplified. The male part 51 may be formed in a perfect circle shape in cross section, and the female part 52 may be formed in a non-circular shape in cross section. The female part 52 having a non-circular cross section can be formed by broaching, for example. In this case, the female part 52 having a non-circular cross section is formed with a higher hardness than the male part 51 having a circular cross section.

  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 that the press-fit portions (plastic joint portions) of both are disposed on the axial center line O of the rolling elements 23 on the inboard side and the outboard side as shown in FIG. . In addition, when arrange | positioning on the axial centerline O, the axial center of a press-fit part is not arrange | positioned on this axial centerline O like FIG. In short, it may be in a range that does not affect the inner race 21 by press-fitting. Here, having no influence means that the rolling of the rolling element 23 is not impaired.

  In the bearing unit shown in FIG. 1, the outer peripheral surface 26a of the outer member 26 is fitted and incorporated into the inner peripheral surface 6a 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 press-fitting 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. FIG. 14 shows a case where the convex portion 6b is omitted, and FIG. 15 shows a case where the retaining ring 53 is omitted (as shown in FIG. 15, 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. 14, 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.

  In addition, the male part is press-fitted into the female part on the axial center line of the inboard-side rolling element and the outboard-side rolling element, so even if the hub wheel is slightly deformed by the press-fitting, the influence will affect the inner race. Can be prevented. For this reason, the stable function is demonstrated as a bearing unit for drive wheels.

  2 and 3 show other configurations of the drive wheel bearing unit. Among these, in the bearing unit of the second embodiment 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. In the third embodiment shown in FIG. 3, the integral inner ring 28 shown in FIG. 2 is divided into two parts in the axial direction and press-fitted into the outer peripheral surface of the hub wheel 10 respectively, and the inner ring 28a, 28b is inserted into each outer peripheral surface. This is an example in which a race 21 is formed. 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. 8 shows an example of this, by extending the cylindrical shaft end of the small-diameter step 13 of the hub wheel 10 until it exceeds 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 the seventh embodiment of FIG. 12, 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 outside. A type formed on the outer peripheral surface of the joint member 31 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, a male part 51 is formed on the outer peripheral surface of the solid end part 16 on the inboard side of the hub wheel 10, and a female part 52 is formed on the inner peripheral surface of the stem part 31 b facing this. 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. 12 illustrates the case where the hub wheel 10 is fitted to the inner periphery of the hollow stem portion 31b and the both are plastic-coupled, but conversely, on the inner periphery of the hollow hub wheel 10 The solid stem portion 31b can be fitted to be plastically coupled to each other.

  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. 9, 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. 9 is equivalent to FIG. 1 in which the inner member 25 is formed by the hub wheel 10 and the inner ring 28, but the same configuration is a view in which the inner member 25 is formed by the integrated inner ring 28 as shown in FIG. The present invention can also be applied to a 2-equivalent product and a product equivalent to FIG. 3 in which the inner member 25 is formed of divided inner rings 28a, 28b as shown in FIG.

  In each above embodiment, although the bearing part 20 which hold | maintained the rolling element 23 with the holder | retainer 24 is illustrated, the total rolling element form which does not use a holder | retainer is also employable. 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. It is desirable to make the diameter smaller than the diameter of the rolling element 23 (particularly, when a ball is used as the rolling element 23, the total clearance is set to about 40% or less of the ball diameter).

  Even in the bearing type using the cage 24, by providing a difference between the PCD of the rolling body row on the outboard side and the PCD of the rolling body row on the inboard side, an effect of increasing rigidity and extending the life can be obtained. I can expect. 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. Even if the PCD of the rolling element row on the inboard side is increased, the PCD of the rolling element row on the outboard side may be increased. 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, 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. 13 shows an eighth embodiment. 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 surface on the outboard side of the flange 11 of the hub wheel 10 and the wheel 80, and holes 71 for inserting wheel 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 form the hub wheel 10 only by forging, and turning is often performed. 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. 13, 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. 13 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. A corresponding bearing unit and a bearing unit corresponding to FIG. 3 in which the inner member 25 is formed by the divided inner rings 28a and 28b can also be employed.

It is sectional drawing of the bearing unit for drive wheels of 1st Embodiment of this invention. It is sectional drawing of the bearing unit for drive wheels of 2nd Embodiment of this invention. It is sectional drawing of the bearing unit for drive wheels of 3rd Embodiment of this invention. It is sectional drawing of a drive shaft. (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 principal part sectional drawing which shows the modification of the wheel bearing unit for drive wheels of the said FIG. It is sectional drawing of the bearing unit for drive wheels of 4th Embodiment of this invention. It is sectional drawing of the bearing unit for drive wheels of 5th Embodiment of this invention. It is sectional drawing of the bearing unit for drive wheels of 6th Embodiment of this invention. It is sectional drawing of the bearing unit for drive wheels of 7th Embodiment of this invention. It is sectional drawing of the bearing unit for drive wheels of 8th Embodiment of this invention. FIG. 6 is a cross-sectional view of a main part showing another modification of the wheel bearing unit for driving wheels of FIG. It is principal part sectional drawing which shows another modification of the wheel bearing unit for drive wheels of the said FIG. It is sectional drawing which shows schematic structure around the suspension apparatus of a vehicle.

Explanation of symbols

6 Knuckle member 6a Inner peripheral surface 10 Hub wheel 21 Inner race 22 Outer race 23 Rolling element 25 Inner member 26 Outer member 26a Outer peripheral surface 30 Outboard side constant velocity universal joint 31 Outer joint member Dn Minimum inner diameter dimension D1 of knuckle member Out Maximum outer diameter of the board side constant velocity universal joint O Axial centerline

Claims (2)

An outer member having a plurality of outer races on the inner periphery, an inner member having a plurality of inner races facing the outer races, a plurality of rows of rolling elements disposed between the outer races and the inner races facing each other, and wheels In a drive wheel bearing unit comprising a hub wheel attached to an outboard and a constant velocity universal joint on the outboard side,
Out of the hub wheel and the outer joint member of the constant velocity universal joint on the outboard side, the male part provided on one side is provided on the other side, and the male part and the female part deformed are pressed into the outer part of the hub wheel and the outer part. A bearing unit for a drive wheel, wherein the joint member is plastically coupled, and the press-fitting portions of the male part and the female part are arranged on the axial center line of the inboard side rolling element and the outboard side rolling element.   The outer peripheral surface of the outer member is fitted and incorporated into 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. Item 2. A drive wheel bearing unit according to Item 1.

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