JP2008001239A - Bearing unit for driving wheel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To add a pre-load to a bearing portion without using a nut. <P>SOLUTION: While a hub wheel 10 and an outside joint member 31 of an out-board side constant velocity universal joint 30 are plastically united, an outer peripheral surface 26a of an external member 26 is pressed in an inner peripheral surface 6a of a knuckle member 6. Therefore, a bearing clearance of a bearing 20 is set to be a negative clearance. <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. 36, 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 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 on the inboard side 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 by fixing the hub wheel 4 and the wheel bearing 3 to the knuckle member 6 in advance, with 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 swung around the kingpin center from the neutral position, 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 the bearing outer ring 3b to the knuckle member 6 and tightening 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. In addition, after bolting the bearing outer ring 3b to the knuckle member 6, it is necessary to apply a preload while managing the tightening torque of the nut, and the preload application operation is complicated.

  By the way, the tightening operation of the nut can be omitted by previously coupling 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 enable preloading to the bearing portion without using a nut.

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

  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, a hub wheel attached to a wheel, and an outboard side constant velocity universal joint, the outer peripheral surface of the outer member is the inner side of the knuckle member on the vehicle body side. It is fitted and incorporated into the peripheral surface, 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, and the bearing gap is set as a negative gap. Here, the term “constant velocity universal joint” includes accessories such as boots and boot bands (hereinafter the same). 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.

  With this configuration, the outer unit of the constant velocity universal joint on the outboard side and the hub wheel are joined together, and the outer member is fitted into the knuckle member from the outboard side to fix the bearing unit to the knuckle member. It becomes possible to do. 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. Further, by setting the bearing gap as a negative gap, the bearing rigidity can be improved and the life of the bearing can be extended.

  When the outer peripheral surface of the outer member is press-fitted into the inner peripheral surface of the knuckle member when fitting and assembling, the outer member and the knuckle member can be firmly coupled simultaneously with the press-fitting. Further, the negative clearance can be set by reducing the bearing clearance accompanying the press-fitting. In this case, since it is not necessary to apply the preload while managing the tightening torque of the nut as in the prior art, the preload applying operation is simplified.

  If the press-fitting allowance is made uniform on the outer diameter side of the plurality of outer races, the negative gap can be stably obtained.

  The bearing gap can also be set to a negative gap by the pre-load applied before fitting and pre-loading and the pre-load applied by fitting and fitting.

  The coupling between the outer joint member and the hub wheel can be performed by using a plastic coupling or welding utilizing the plastic flow of the material, or by using a nut as in the conventional case. As an example of plastic coupling, the hub ring and the outer joint can be obtained by press-fitting a male part provided on one of the hub ring and the outer joint member into the other and a male part different from the male part. A material obtained by plastic bonding with a member is exemplified. 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, workability is also good.

  In addition, the coupling structure of the outer joint member and the hub wheel includes a structure in which the hub wheel and the outer joint member are coupled by expansion caulking, a structure in which the hub wheel and the outer joint member are coupled by welding, and the inner peripheral surface of the hub ring. Examples include a spline interposed between the outer joint surface of the outer joint member and a combination of the hub wheel and the outer joint member by swinging caulking.

  ADVANTAGE OF THE INVENTION According to this invention, the assembly | attachment process to the knuckle member of the bearing unit for drive wheels containing a hub ring, a bearing, and an outboard side constant velocity universal joint can be simplified. Further, when applying the preload to the bearing portion, it is not necessary to tighten the nut and manage the tightening torque, so that the preload applying operation can be simplified.

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

  FIG. 1 shows a drive wheel bearing unit according to a first embodiment of the present invention. The drive wheel bearing unit 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 screwed into 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 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 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 coupled to the hub wheel 10 by various coupling structures described later. As a coupling method, a reversible separation / joining method using a nut may be employed, but preferably, the hub wheel 10 and the outer joint member 31 are not allowed to be reversibly separated / joined. Adopting the joint structure.

  When the hub wheel 10 and the outer joint member 31 are non-separably 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 on the outboard side of the inner ring 28 is also a hub. By abutting with the wheel 10 in the axial direction, the interval between the double-row inner races 21 is maintained at a specified dimension, and a preload (preliminary preload) is applied.

  In the present invention, the outer peripheral surface 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. By fitting and fitting, the bearing gap of the bearing portion 20 is set to a negative gap.

  As used herein, fitting and fitting means that the fitting of the outer member 26 and the knuckle member 6 completes the fitting of both. 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. FIG. 34 shows a case where the convex portion 6b is omitted, and FIG. 35 shows a case where the retaining ring 53 is omitted (as shown in FIG. 35, 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.

  Further, by pressing the outer member 26 into the knuckle member 6, the bearing gap is reduced after the press-fitting. 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. When the convex part 6b is provided in the inner peripheral surface of the knuckle member 6 like embodiment shown in FIGS. 1-3, the internal diameter dimension of the convex part 6b becomes a "minimum internal diameter dimension." When the convex portion 6b is omitted as shown in FIG. 37, the inner peripheral surface 6a of the knuckle member 6 becomes the “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 a 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, at the time of press-fitting, a predetermined preload can be applied to the bearing portion 20 to set the bearing gap as a negative gap. .

  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.

  The hub wheel 10 and the outer joint member 31 are plastically coupled. For example, the plastic coupling is performed by forming the male part 51 on one of the hub wheel 10 and the outer joint member 31 and forming the male part 51 and the deformed female part 52 on the other member. This is done by press-fitting 51 and female part 52 to each other. 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, 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. 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 increased. If sufficient bonding strength can be obtained only by press-fitting, this caulking step can be omitted.

  In this bonded 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. 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 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 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.

  As the drive wheel bearing unit, an inner race 21 on the outboard side is formed on the outer peripheral surface of the hub wheel 10 as in the second to eighth embodiments shown in FIGS. A type in which the race 21 is formed on the outer peripheral surface of the outer joint member 31 can also be used. 11 to 17, the hub wheel 10 and the outer joint member 31 are non-separably coupled, and the shoulder surface 38 and the end surface of the outer joint member 31 are in contact with the hub wheel 10 in the axial direction. The dimension between the inner races 21 in the row 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.

  In any of the bearing units shown in FIGS. 11 to 17, 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, and the maximum outer diameter of the constant velocity universal joint 30 on the outboard side. Is smaller than the minimum inner diameter of the knuckle member 6. The bearing gap is set to a negative gap.

  Among these, the second embodiment shown in FIG. 11 is one in which the hub wheel 10 and the outer joint member 31 are plastically coupled by diameter expansion caulking. In the diameter expansion caulking, the stem portion 31b of the outer joint member 31 is formed hollow, and a small-diameter portion 31b1 having an inner diameter smaller than that of the other portion is formed at the end portion on the outboard side. After the stem portion 31b is inserted into the inner periphery of the hub wheel 10, a mandrel having a diameter larger than the inner diameter of the small diameter portion 31b1 is pushed into the inner periphery of the stem portion 31b to increase the diameter of the small diameter portion 31b1, and the inner diameter of the hub wheel 10 is increased. The hub wheel 10 and the outer joint member 31 are plastically coupled by being brought into pressure contact with the peripheral surface. If the concavo-convex portion 15 is formed in advance on the inner peripheral surface of the hub wheel 10 by knurling or the like and the concavo-convex portion 15 is hardened by heat treatment, the concavo-convex portion 15 is formed on the outer peripheral surface of the stem portion 31b by expanding the small diameter portion 31b1. Thus, the hub wheel 10 and the outer joint member 31 can be firmly plastically coupled.

  In addition, when the stem portion 31b of the outer joint member 31 is formed to be hollow as in diameter expansion caulking, the inside of the stem portion 31b is avoided in order to avoid a situation such as entry of foreign matter into the mouth portion 31a and outflow of grease. It is desirable to attach a cap 39 to the peripheral surface.

  In the third embodiment shown in FIG. 12, the hub wheel 10 and the outer joint member 31 are non-separated by a method called swing caulking. In the swing caulking, the shaft end on the outboard side of the stem portion 31b is formed in a cylindrical shape, and the flange 31b2 is formed by plastically deforming the cylindrical portion to the outer diameter side by swinging the caulking tool. The flange 31b2 is brought into contact with the end surface of the hub wheel 10 to prevent the hub wheel 10 from coming off, and the spline 60 is formed between the inner peripheral surface of the hub wheel 10 and the outer peripheral surface of the stem portion 31b. Thus, the hub wheel 10 and the outer joint member 31 are prevented from rotating.

  In the fourth embodiment shown in FIG. 13, the hub wheel 10 and the outer joint member 31 are joined in a non-separable manner by welding (the welded portion is indicated by reference numeral 61). Examples of the welding method include laser beam welding, plasma welding, electron beam welding, and high-speed pulse projection welding. Since the stem portion 31b is press-fitted into the inner periphery of the hub wheel 10 and torque can be transmitted through the press-fitting fitting surface, the load applied to the welded portion 61 is small. Less welding method can be adopted.

  11 to 13 exemplify the case where the stem portion 31b is fitted to the inner periphery of the hub wheel 10, conversely, the hub wheel 10 is fitted to the inner periphery of the hollow stem portion 31b. The two can also be joined in a non-separable manner (see FIGS. 14 to 17).

  Among these, in the fifth embodiment shown in FIG. 14, the male part 51 and the female part 52 are formed differently from each other, and the male part 51 is press-fitted into the female part 52, as in the first embodiment shown in FIG. 1. By doing so, the hub wheel 10 and the outer joint member 31 are plastically coupled. In this case, in the hub wheel 10, a male part 51 is formed on the outer peripheral surface of the solid end part 16 on the inboard side, and a female part 52 is formed on the inner peripheral surface of the stem part 31b facing this. Similarly to the embodiment shown in FIG. 1, after the male portion 51 is press-fitted, the flange portion 58 is further formed by caulking the outer peripheral portion of the solid shaft end 16 of the hub wheel 10 by the method shown in FIG. 9. Bond strength can be increased.

  In the sixth embodiment shown in FIG. 15, the hub wheel 10 and the outer joint member 31 are plastically coupled by the above-described diameter expansion caulking. That is, the small diameter portion 31b1 of the hollow hub wheel 10 is expanded and deformed by a mandrel, and the concave and convex portions 15 formed on the inner peripheral surface of the stem portion 31b are bitten to plastically couple the hub wheel 10 and the outer joint member 31. . In the seventh embodiment shown in FIG. 16, the hub wheel 10 and the outer joint member 31 are plastically coupled by the above-described swing caulking. A cylindrical portion formed at the solid shaft end 16 on the inboard side of the hub wheel 10 is plastically deformed by swinging and caulking to form a flange 17, which is in close contact with the mouth portion 31a. In the eighth embodiment shown in FIG. 17, both members are joined in a non-separated manner by the above welding method (the welded portion is indicated by reference numeral 61).

  2 and 3 show ninth and tenth embodiments of the drive wheel bearing unit. Among these, FIG. 2 shows a ninth embodiment. In this bearing unit, the inner race 21 of the integral structure in which the double row inner races 21 of the bearing portion 20 are press-fitted into the outer periphery of the hub wheel 10 is shown. Is formed. In this case, the inner ring 28 constitutes the inner member 25 having the double-row inner race 21. FIG. 3 shows a tenth embodiment, in which 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, and the outer circumferences of the two inner rings 28 a and 28 b are shown. This is an example in which an inner race 21 is formed on the surface. 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.

  2 and 3, 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, and the maximum outer diameter of the constant velocity universal joint 30 on the outboard side. Is smaller than the minimum inner diameter of the knuckle member 6, and the bearing gap is set to a negative gap.

  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.

  FIG. 18 illustrates an example in which the hub wheel 10 and the outer joint member 31 are coupled to each other at the end portion on the outboard side in the bearing units illustrated in FIGS. In FIG. 18, the left column (reference numerals 1, 4, 7) represents the bearing unit equivalent shown in FIG. 1, and the middle column (reference numerals 2, 5, 8) represents the bearing unit equivalent shown in FIG. The right column (reference numerals 3, 6 and 9) in the column represents the bearing unit equivalent product shown in FIG. Further, the upper row (reference numerals 1 to 3) represents the one to which the diameter expansion caulking is applied, the middle row (reference numerals 4 to 6) represents the one to which the swing caulking is applied, and the lower row (reference numerals 7 to 9). Represents the one to which welding is applied.

  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 the embodiment. The cylindrical shaft end of the small-diameter step portion 13 of the hub wheel 10 is extended to exceed the inboard side end surface of the inner ring 28, and the caulking tool is swung on the inner diameter side of the protruding portion. By doing so, the protruding portion is plastically deformed to the outer diameter side to form the flange 17. 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 each of the above embodiments, 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. 19 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 in the eleventh embodiment shown in FIG. 20, 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 are used. By providing a difference between them, an effect of increasing rigidity and extending the 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. 20 illustrates the case where the PCD (P2) of the rolling element row on the inboard side is increased. However, as shown in FIG. 21, the PCD (P1) of the rolling element row on the outboard side is increased. 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. 22A and 22B, 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. 23 shows a twelfth embodiment of the drive wheel bearing unit. Also in this bearing unit, 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, and the maximum outer diameter of the constant velocity universal joint 30 on the outboard side is the minimum inner diameter of the knuckle member 6. The bearing gap is set to a negative gap.

  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. 24, 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. 26, a cored bar 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. 27, 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 27a 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. 28, the bearing outer ring 261 on the inboard side is inserted into the outer periphery of the hub ring 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. 29, 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. 30, 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, the hub wheel 10 is non-separated from the outer joint member 31 of the outboard side constant velocity universal joint 30. The coupling method at this time is arbitrary and, like the bearing unit of FIGS. 1 to 3, in addition to press-fitting the male part 51 into the female part 52 for plastic coupling, the above-mentioned diameter expansion caulking, swing caulking, or It can also couple | bond by means, such as welding. 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, as shown in FIG. 23, a retaining ring 53 that engages with the end face on the outboard side of the bearing outer ring 262 is used. In addition, as 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. 31 shows a thirteenth embodiment of the present invention. Also in this bearing unit, 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, and the maximum outer diameter of the constant velocity universal joint 30 on the outboard side is the minimum inner diameter of the knuckle member 6. The bearing gap is set to a negative gap.

  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 FIG. 1, the pilot portion 72 is usually formed integrally with the end portion on the outboard side of the hub wheel 10, and therefore 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. 31, 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. 31 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 the same 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. 32) and a bearing unit equivalent to FIG. 3 (see FIG. 33) in which the inner member 25 is formed by the divided inner rings 28a and 28b can also be adopted. In the bearing unit shown in FIGS. 31 to 33, the hub wheel 10 and the inner rings 28, 28a, and 28b are positioned by the flange 17 by swing caulking, but this positioning is stopped as shown in FIG. It can also be done with the wheel 29.

It is sectional drawing of the bearing unit for drive wheels concerning 1st Embodiment. It is sectional drawing of the bearing unit for drive wheels concerning 9th Embodiment. It is sectional drawing of the bearing unit for drive wheels concerning 10th Embodiment. 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 a principal part expanded sectional view of the wheel bearing unit for drive wheels. It is sectional drawing of the bearing unit for drive wheels concerning 2nd Embodiment. It is sectional drawing of the bearing unit for drive wheels concerning 3rd Embodiment. It is sectional drawing of the bearing unit for drive wheels concerning 4th Embodiment. It is sectional drawing of the bearing unit for drive wheels concerning 5th Embodiment. It is sectional drawing of the bearing unit for drive wheels concerning 6th Embodiment. It is sectional drawing of the bearing unit for drive wheels concerning 7th Embodiment. It is sectional drawing of the bearing unit for drive wheels concerning 8th Embodiment. It is a figure which shows the structure at the time of applying diameter expansion caulking, rocking caulking, and welding in the bearing unit shown in FIGS. It is a front view showing a total rolling element type bearing structure. It is sectional drawing of the bearing unit for drive wheels concerning 11th Embodiment. 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 concerning 12th Embodiment. 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 concerning 13th Embodiment. 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.

Explanation of symbols

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 dimension 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 (5)

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,
The outer peripheral surface of the outer member is fitted and integrated with the inner peripheral surface of the knuckle member on the vehicle body side, the maximum outer diameter of the constant velocity universal joint on the outboard side is smaller than the minimum inner diameter of the knuckle member, and the bearing clearance is a negative clearance. A drive wheel bearing unit characterized by being set to.   The drive wheel bearing unit according to claim 1, wherein the outer peripheral surface of the outer member is press-fitted into the inner peripheral surface of the knuckle member.   The bearing unit for a drive wheel according to claim 2, wherein the press-fitting allowance is made uniform on the outer diameter side of the plurality of outer races.   The bearing unit for a drive wheel according to any one of claims 1 to 3, wherein the bearing gap is set to a negative gap by a pre-load applied before fitting and pre-loading applied by fitting and fitting.   Claims in which the hub ring and the outer joint member are plastically connected by press-fitting the male part provided on one of the hub wheel and the outer joint member into the other and the male part and the female part of the deformed shape. Item 5. The drive wheel bearing unit according to any one of Items 1 to 4.

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