JP2007290591A - Bearing device for driving wheel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bearing device for a driving wheel, which improves workability in assembly/disassembly to reduce the cost and obtains reliability and operational stability by eliminating circumferential rattling of an engaging part. <P>SOLUTION: In the bearing device for the driving wheel, a hub wheel 1 provided with a wheel mounting flange 4 at an end in an integrating manner, a double row rolling bearing 2 and a constant velocity universal joint 3 are unified in a detachable manner by a screw means. The constant velocity universal joint 3 is connected to the hub wheel 1 by the intermediary of a torque transmission means. The torque transmission means comprises an engaging profile 21 in which a plurality of projecting teeth 21a are arranged at equal intervals on an outer periphery of a shaft part 20, and an engaging profile 22 in which a plurality of recessed grooves 22a are arranged correspondingly at equal intervals on an inner periphery of the hub wheel 1 in a manner of engaging the projecting teeth 21a. The projecting teeth 21a have negative pressure angles of 0 to -30°, and the tooth flanks have axial-directional angles of inclination of 2 to 7° to a shaft center. A hardened layer 33 having a surface hardness in the range of 58 to 64 HRC obtained by induction-hardening is formed on the projecting teeth 21a. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a drive wheel bearing device that rotatably supports a drive wheel of a vehicle such as an automobile. Specifically, the bearing unit and a constant velocity universal joint are detachably unitized, and the torque transmission unit The present invention relates to a bearing device for a drive wheel that suppresses rattling in the circumferential direction without strictly regulating the shape and dimensions, and achieves reliability and steering stability.

  A power transmission device that transmits engine power of a vehicle such as an automobile to a wheel transmits power from the engine to the wheel, and also causes radial or axial displacement from the wheel that occurs when the vehicle bounces or turns when traveling on a rough road. In addition, one end of the drive shaft that is interposed between the engine side and the drive wheel side is connected to the differential through a sliding type constant velocity universal joint, and the other end is It is connected to the wheel via a drive wheel bearing device including a fixed type constant velocity universal joint.

  Various types of drive wheel bearing devices have been proposed in the past. For example, a device as shown in FIG. 8 is known. This bearing device for a drive wheel is connected to a hub wheel 51 that mounts a drive wheel (not shown) at one end, a double row rolling bearing 52 that rotatably supports the hub wheel 51, and the hub wheel 51. A fixed type constant velocity universal joint 53 for transmitting the power of a drive shaft (not shown) to the hub wheel 51 is provided.

  The hub wheel 51 integrally has a wheel mounting flange 54 for mounting a drive wheel at one end, an inner rolling surface 51a on the outer periphery, and a cylindrical small-diameter step portion extending in the axial direction from the inner rolling surface 51a. 51b is formed. The double-row rolling bearing 52 has a vehicle body mounting flange 55b integrally fixed to a suspension device (not shown) on the outer periphery, and an outer side in which double-row outer rolling surfaces 55a and 55a are formed on the inner periphery. It comprises a member 55 and an inner member 57 inserted into the outer member 55 via double rows of balls 56.

  The inner member 57 includes a hub wheel 51 and a separate inner ring 58 that is press-fitted into the small-diameter step portion 51b of the hub wheel 51 and has an inner rolling surface 58a formed on the outer periphery. The inner ring 58 is fixed to the hub wheel 51 in the axial direction by a caulking portion 51 c formed by plastically deforming the end portion of the small-diameter stepped portion 51 b of the hub wheel 51 radially outward.

  The constant velocity universal joint 53 includes an outer joint member 62 integrally including a cup-shaped mouth portion 59, a shoulder portion 60 that forms the bottom of the mouth portion 59, and a shaft portion 61 that extends from the shoulder portion 60 in the axial direction. I have. The outer joint member 62 is fitted into the hub wheel 51 so that torque can be transmitted. That is, a female spline 63 is formed on the inner periphery of the hub wheel 51, a male spline 64 is formed on the outer periphery of the shaft portion 61 of the outer joint member 62, and both the splines 63 and 64 are engaged with each other.

  A locking step 65 is formed at the outer end of the inner peripheral surface of the hub wheel 51, and a locking groove 66 is formed at the tip of the shaft portion 61 corresponding to the locking step 65. A retaining ring 67 is mounted in the locking groove 66 in advance. When the shaft portion 61 of the outer joint member 62 is fitted into the hub wheel 51, the retaining ring 67 passes through the female spline 63 while reducing the diameter. The retaining ring 67 is aligned with the engaging step portion 65 at a position where the axial clearance remains between the caulking portion 51c and the shoulder portion 60 of the hub wheel 51. In this state, the diameter of the retaining ring 67 is elastically changed. The retaining ring 67 is restored to be freely spanned between the locking step portion 65 and the locking groove 66, and the hub wheel 51 and the outer joint member 62 are coupled so as to be separable in the axial direction. Further, a seal ring 68 is fitted on the shoulder portion 60 of the outer joint member 62, and the lip of the seal ring 68 abuts against the inner end surface of the crimping portion 51c, thereby closing the clearance between the crimping 51c and the shoulder portion 60. It is out.

  Here, the male spline 64 is a tapered spline tooth whose width in the circumferential direction becomes wider toward the inner end side. On the other hand, the female spline 63 is a tapered spline tooth whose width in the circumferential direction becomes wider toward the outer end side. Then, as the male spline 64 is inserted into the female spline 63, the tooth surfaces are brought into close contact with each other and engaged in the circumferential direction without rattling.

  Further, a cap 69 serving as a closing member is attached to the opening of the hub wheel 51. A circular through hole 69 a is formed at the center of the cap 69, and a screw hole 61 a is formed at the center of the outer end surface of the shaft portion 61. The bolt 70 inserted through the through hole 69a is screwed into the screw hole 61a and tightened. As a result, since the axial force is still applied to the bolt 70 based on the elastic deformation of the cap 69, the bolt 70 is prevented from being unintentionally loosened, and the engaging portions of both the splines 63 and 64 are prevented. It is possible to further prevent rattling in the circumferential direction.

A large torque is applied to the drive wheels of such a vehicle from the engine via a sliding type constant velocity universal joint (not shown) when the engine rotates at a low speed, for example, when the vehicle starts, and the drive shaft may be twisted. Are known. As a result, the inner member 57 of the double row rolling bearing 52 that supports the drive shaft is also twisted. In this way, even if a large twist occurs in the drive shaft, the circumferential direction between the female spline 63 of the hub wheel 51 and the male spline 64 of the shaft portion 61 fitted in the hub wheel 51 is here. Since sticking is prevented, generation of an unpleasant rattling noise can be prevented over a long period of time.
JP 2002-120506 A

  In such a conventional drive wheel bearing device, both the splines 63 and 64 are engaged in a wedge shape as tapered spline teeth, thereby preventing rattling in the circumferential direction at the engaging portion and generating an unpleasant rattling noise. It has a feature that can be prevented over a long period of time. However, since the male spline 64 of the shaft portion 61 is premised on finishing by rolling, for example, it is difficult to form a large taper angle, and the range of 0.75 to 1.25 ° is the limit. As the taper angle is smaller, the variation in dimensional accuracy changes the axial engagement position of the male spline 64, and as a result, the distance between the wheel mounting flange 54 and the center of the constant velocity universal joint 53 is greatly changed. This is not preferable because of the characteristics of the vehicle drive system.

  Further, since the expansion of the hub wheel 51 due to the wedge effect of both the splines 64 and 63 affects the bearing clearance, a large axial force cannot be applied in the axial direction by the bolt 70. Further, conversely, if the taper angle is increased, the axial separation force generated at the engaging portions of both the splines 64 and 63 at the time of torque transmission increases, which adversely affects the reliability and strength of the fastening portion, and the engaging portion. This is not preferable because an abnormal noise is generated.

  The present invention has been made in view of such circumstances, and improves the workability at the time of disassembling / assembling to reduce the cost, and eliminates the backlash in the circumferential direction of the engaging portion, thereby improving reliability and steering stability. An object of the present invention is to provide a bearing device for a drive wheel that achieves the above.

  In order to achieve the object, the invention according to claim 1 of the present invention includes an outer member having a double row outer rolling surface formed on the inner periphery, and a wheel mounting flange for mounting the wheel at one end. The double-row outer rolling comprising: a hub wheel integrally formed with a cylindrical small-diameter stepped portion extending in the axial direction on the outer periphery, and at least one inner ring press-fitted into the small-diameter step portion of the hub ring. An inner member in which a double-row inner rolling surface facing the surface is formed, a double-row rolling element housed so as to roll between the rolling surfaces, and a constant velocity universal joint, An outer joint member that is coupled to the hub wheel in an axially separable manner through screw means. The outer joint member includes a cup-shaped mouth portion, a shoulder portion that forms the bottom of the mouth portion, and the shoulder portion. And a shaft portion extending in an axial direction from the portion, and the shaft portion provides torque transmission means to the hub wheel. In the drive wheel bearing device fitted therein, the torque transmission means corresponds to the fitting profile formed by arranging a plurality of convex teeth on the outer periphery of the shaft portion, and the fitting profile, And a fitting profile formed by arranging a plurality of concave grooves having a cross-sectional dovetail shape engaging with the convex teeth on the inner periphery of the hub wheel, and the convex teeth are formed in a substantially trapezoidal cross section. And a predetermined inclination angle in the axial direction with respect to the axial center is formed on the tooth surface, and the surface hardness is 58 to 64 HRC by induction hardening from the shoulder portion to the convex teeth of the shaft portion. A predetermined hardened layer is formed in the range.

  As described above, the hub wheel integrally having the wheel mounting flange at one end, the double row rolling bearing and the constant velocity universal joint are detachably unitized through the screw means, and the constant velocity universal joint is connected to the hub wheel. In the drive wheel bearing device coupled through the torque transmission means, the torque transmission means corresponds to the fitting profile formed by arranging a plurality of convex teeth on the outer periphery of the shaft portion, and the fitting profile. It is composed of a fitting profile formed by arranging a plurality of concave grooves having a cross-sectional dovetail shape engaging with the convex teeth on the inner periphery of the hub wheel, and the convex teeth are formed in a substantially trapezoidal cross section with a predetermined pressure. A predetermined inclination angle is formed on the tooth surface in the axial direction with respect to the axial center, and the surface hardness is predetermined in the range of 58 to 64 HRC by induction hardening from the shoulder portion to the convex teeth of the shaft portion. As the hardened layer is formed, excessive There is no need for input, and it is possible to easily obtain a strong fitting state with no play in the circumferential direction at the final stage of insertion, while suppressing the combined tolerance range of the engaging portions due to heat treatment deformation, and projecting during torque transmission It is possible to suppress the radially outward component force generated at the engaging portions of the teeth and the groove.

  Preferably, as in the invention described in claim 2, if the pressure angle at the tooth surfaces of the convex teeth and the concave grooves is set in a range of 0 to −30 °, the amount of expansion of the hub wheel during torque transmission And an increase in the separation force generated in the engaging portion can be effectively suppressed.

  More preferably, as in the invention described in claim 3, if the inclination angle of the tooth surfaces of the convex teeth and the concave grooves is set in a range of 2 to 7 °, the combined tolerance width of the tooth surfaces is ± 1 mm. The axial clearance between the shoulder portion and the end face of the crimping portion can be secured.

  According to a fourth aspect of the present invention, the inner ring is fixed in the axial direction with respect to the hub ring by a caulking portion formed by plastically deforming the end portion of the small diameter step portion radially outward. The shaft portion of the outer joint member is fitted to the hub wheel via the fitting profile such that a predetermined axial clearance is interposed between the shoulder portion and the end surface of the crimping portion. Thus, a self-retaining structure can be provided, the bearing preload can be maintained for a long time without firmly tightening the screw means, and even if a large torque is applied to the outer joint member and the torsion occurs, the stick There is no slip noise.

  Further, as in the fifth aspect of the present invention, if a predetermined hardened layer is formed in the concave groove of the fitting profile in the hub wheel by induction hardening in a range of 58 to 64 HRC, convex teeth Thus, the weight of the engaging portion can be reduced, the wear resistance can be improved, and the durability can be ensured over a long period of time.

  A bearing device for a driving wheel according to the present invention integrally has an outer member having a double row outer raceway formed on the inner periphery and a wheel mounting flange for mounting a wheel on one end, and a shaft on the outer periphery. A hub ring formed with a cylindrical small-diameter step portion extending in the direction, and at least one inner ring press-fitted into the small-diameter step portion of the hub ring, and the inner side of the double row facing the outer rolling surface of the double row An inner member in which a rolling surface is formed, a double-row rolling element that is rotatably accommodated between the both rolling surfaces, and a constant velocity universal joint are configured, and a screw means is attached to the hub wheel. An outer joint member coupled in an axially separable manner, the outer joint member comprising a cup-shaped mouth portion, a shoulder portion forming the bottom of the mouth portion, and a shaft portion extending in the axial direction from the shoulder portion And the shaft is internally fitted to the hub wheel via torque transmission means. In the bearing device, the torque transmission means corresponds to the fitting profile formed by arranging a plurality of convex teeth on the outer periphery of the shaft portion, and corresponds to the fitting profile, And a fitting profile formed by arranging a plurality of concave grooves having a cross-sectional dovetail shape engaging with the convex teeth, the convex teeth being formed in a substantially trapezoidal cross section, having a predetermined pressure angle, A predetermined inclination angle is formed in the tooth surface in the axial direction with respect to the axial center, and a predetermined hardened layer is formed in the range of 58 to 64 HRC by induction hardening from the shoulder portion to the convex teeth of the shaft portion. As a result, it is possible to obtain a strong fitting state with no circumferential backlash at the final stage of insertion easily without requiring excessive pressure input, and to increase the combined tolerance width of the engaging portion by heat treatment deformation. Convex teeth and concave grooves during torque transmission It is possible to suppress the component force in the radially outward occur engaging portion.

  A vehicle body mounting flange is integrally formed on the outer periphery, an outer member having a double row outer rolling surface formed on the inner periphery, a wheel mounting flange is integrally formed on one end, and the double row outer rolling is formed on the outer periphery. One inner rolling surface facing the running surface, a hub ring formed with a cylindrical small-diameter stepped portion extending in the axial direction from the inner rolling surface, and a small-diameter stepped portion of the hub wheel are press-fitted to the outer periphery. An inner member formed of an inner ring on which the other inner rolling surface facing the outer rolling surface of the double row is formed, and a double row rolling element housed so as to roll freely between the two rolling surfaces; A constant velocity universal joint, and an outer joint member coupled to the hub wheel via a fastening bolt so as to be separable in the axial direction, and plastically deforming an end portion of the small diameter step portion radially outward. The inner ring is fixed in the axial direction by the formed caulking portion, and the outer joint member includes a cup-shaped mouth portion and The shoulder portion that forms the bottom of the mouth portion and the shaft portion that extends in the axial direction from the shoulder portion are integrally formed, and a predetermined axial clearance is interposed between the shoulder portion and the end surface of the crimping portion. In the drive wheel bearing device in which the shaft portion is fitted in the hub wheel via the torque transmission means, the torque transmission means is formed by a plurality of convex teeth arranged on the outer periphery of the shaft portion. And a fitting profile corresponding to the fitting profile and formed by arranging a plurality of concave grooves having a cross-sectional dovetail shape engaging the convex teeth on the inner periphery of the hub wheel. The convex teeth are formed in a substantially trapezoidal cross section, have a negative pressure angle of 0 to -30 °, and have an inclined angle of 2 to 7 ° in the axial direction with respect to the axial center on the tooth surface, Surface hardness is in the range of 58 to 64 HRC by induction hardening over the convex teeth of the shaft part Constant of the hardened layer is formed.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
1 is a longitudinal sectional view showing a first embodiment of a bearing device for a drive wheel according to the present invention, FIG. 2 (a) is a front view showing a fitting profile of a shaft portion of FIG. 1, and FIG. FIG. 3 is a cross-sectional view taken along line II-II in FIG. 3A, FIG. 3 is an enlarged view of the main part of FIG. 1, and FIG. 4 shows the expansion amount of the hub wheel and the separation force generated in the engaging part with respect to the pressure angle. FIG. 5 is a graph showing the expansion amount of the hub wheel with respect to the inclination angle and the separation force generated in the engaging portion. In the following description, the side closer to the outer side of the vehicle in a state assembled to the vehicle is referred to as the outer side (left side in the drawing), and the side closer to the center is referred to as the inner side (right side in the drawing).

This drive wheel bearing device has a so-called third generation configuration in which the hub wheel 1, the double row rolling bearing 2 and the constant velocity universal joint 3 are detachably unitized.
The double-row rolling bearing 2 includes an outer member 7, an inner member 8, and double-row rolling elements (balls) 9 and 9. The outer member 7 is made of medium carbon steel containing 0.40 to 0.80 wt% of carbon such as S53C, and integrally has a vehicle body mounting flange 7b for mounting to the vehicle body (not shown) on the outer periphery. Are formed with double-row outer rolling surfaces 7a, 7a. The double row outer rolling surfaces 7a, 7a are subjected to a hardening process in a range of 58 to 64 HRC by induction hardening.

  On the other hand, the inner member 8 is formed with double-row inner rolling surfaces 1a and 5a facing the outer rolling surfaces 7a and 7a of the outer member 7 described above. Of these double-row inner rolling surfaces 1a, 5a, one (outer side) inner rolling surface 1a is on the outer periphery of the hub wheel 1, and the other (inner side) inner rolling surface 5a is on the outer periphery of the inner ring 5, respectively. It is integrally formed. In this case, the inner member 8 refers to the hub wheel 1 and the inner ring 5. And the double row rolling elements 9 and 9 are accommodated between these both rolling surfaces, respectively, and are hold | maintained by the holder | retainers 10 and 10 so that rolling is possible. Further, seals 11 and 12 are attached to the opening of the annular space formed between the outer member 7 and the inner member 8, and leakage of the lubricating grease sealed inside the bearing and the inside of the bearing from the outside. Prevents intrusion of rainwater and dust.

  The hub wheel 1 integrally has a wheel mounting flange 4 for mounting a wheel (not shown) at an end on the outer side, and hub bolts 4a for fixing the wheel in the circumferential direction of the wheel mounting flange 4 are planted. It is installed. And the inner side rolling surface 1a and the cylindrical small diameter step part 1b extended in an axial direction from this inner side rolling surface 1a are formed in the outer periphery via the seal land part 13 used as the base of the wheel mounting flange 4. FIG. The inner ring 5 is press-fitted into the small-diameter step portion 1b via a predetermined scissors, and further, a bearing preload is applied by a crimping portion 6 formed by plastically deforming an end portion of the small-diameter step portion 1b radially outward. In this state, it is fixed to the hub wheel 1 in the axial direction.

  The hub wheel 1 is made of medium carbon steel containing 0.40 to 0.80 wt% of carbon such as S53C, and the outer periphery extends from the seal land portion 13 to which the outer seal 11 is in sliding contact to the inner rolling surface 1a and the small diameter step portion 1b. A predetermined hardened layer 32 having a surface hardness in the range of 58 to 64 HRC is formed on the surface by induction hardening (indicated by cross-hatching in the figure). In addition, the crimping part 6 is made into the surface hardness after a forge process. The inner ring 5 is made of high carbon chrome bearing steel such as SUJ2, and is hardened in the range of 58 to 64 HRC up to the core portion by quenching. As a result, not only the wear resistance of the seal land 13 is improved, but also the mechanical strength against the rotational bending load applied to the wheel mounting flange 4 is sufficient, and the durability of the hub wheel 1 is further improved. To do. In addition, fretting wear occurring on the fitting surface between the small diameter step 1b and the inner ring 5 can be minimized. Here, the third generation structure in which the inner raceway surface 1a is directly formed on the outer periphery of the hub wheel 1 is illustrated. However, the present invention is not limited to this, but a pair of inner rings are press-fitted into the hub wheel. It may be a first or second generation structure. Moreover, although the structure which consists of a double row angular contact ball bearing which used the ball for the rolling element 9 was illustrated, the double row tapered roller bearing which used the tapered roller for the rolling element 9 may be sufficient.

  The constant velocity universal joint 3 includes an outer joint member 14, a joint inner ring 15, a cage 16 and a torque transmission ball 17. The outer joint member 14 has a cup-shaped mouth portion 18, a shoulder portion 19 that forms the bottom portion of the mouth portion 18, and a hollow shaft portion 20 that extends in the axial direction from the shoulder portion 19. Curved track grooves 18a and 15a extending in the axial direction are formed on the inner periphery of the inner ring 15 and the outer periphery of the joint inner ring 15, respectively. The outer joint member 14 is made of medium carbon steel containing 0.40 to 0.80 wt% of carbon such as S53C, and the track grooves 18a and 15a are hardened by induction hardening to a surface hardness of 58 to 64 HRC. Yes.

  Here, the shaft portion 20 of the outer joint member 14 is constituted by a short shaft, and a female screw 20a is formed at an end portion on the outer side. As shown in FIG. 2, a fitting profile 21 in which a plurality (3 to 10) of convex teeth 21 a are arranged on the outer periphery is formed. The convex tooth 21a is formed into a substantially trapezoidal cross section by machining such as an end mill, has a predetermined pressure angle α, and has a predetermined inclination angle β in the axial direction with respect to the axial center of the tooth surface. Yes. On the other hand, on the inner periphery of the hub wheel 1, a fitting profile 22 is formed in which a plurality of concave grooves 22a corresponding to the fitting profile 21 are equally arranged. The concave groove 22a is formed in a dovetail shape by forging, has a predetermined pressure angle α corresponding to the convex tooth 21a, and the tooth surface has a predetermined inclination angle in the axial direction with respect to the axial center. β is formed.

  The graph shown in FIG. 4 shows the amount of expansion of the hub wheel 1 with respect to the pressure angle α during torque transmission and the separation force generated in the engaging portion with constant axial force and torque, and these convex teeth 21a and The pressure angle α of the concave groove 22a is set in a range of ± 30 ° in which both the expansion amount and the separation force do not increase. Preferably, when the pressure angle α is set in a negative region, that is, in a range of 0 to −30 °, the cross-sectional shape of the concave groove 22a in the hub wheel 1 becomes a dovetail shape, which effectively expands the hub wheel 1. Can be suppressed. Here, as shown in FIG. 2 (c), the pressure angle α is defined as a state in which the convex teeth 21a go outward in the circumferential direction and the tooth width increases, and the tooth width is negative (α <0). Is positive (α> 0).

  The graph shown in FIG. 5 shows the expansion amount of the hub wheel 1 with respect to the inclination angle β during torque transmission and the separation force generated in the engaging portion with constant axial force and torque. The inclination angle β of the concave groove 22a is set in the range of 2 to 7 °, preferably 3 to 6 °, in which both the expansion amount and the separation force do not increase. As the inclination angle β decreases, the combined tolerance width of the convex teeth 21a and the recessed grooves 22a increases. However, by setting β = 2 to 7 °, the combined tolerance width can be suppressed to ± 1 mm or less. An axial clearance δ between a shoulder 19 described later and the end face of the crimping portion 6 can be secured. Here, the module m is set to 3 to 10 in consideration of the strength and economic aspects of the convex teeth 21a and the concave grooves 22a (approximately 3 to 10 teeth). Here, m = d / z (d: average diameter in the axial direction of the fitting profile, z: number of teeth or number of grooves).

  Further, a predetermined hardened layer 33 is formed in the range of 58 to 64 HRC by induction hardening from the shoulder portion 19 of the outer joint member 14 to the convex teeth 21a of the shaft portion 20 (cross-hatching in the figure). ). On the other hand, a predetermined hardened layer 34 is formed in the concave groove 22a of the fitting profile 22 in the hub wheel 1 engaged with the convex tooth 21a by induction hardening so that the surface hardness is in the range of 58 to 64 HRC (in the drawing). (Indicated by cross-hatching). Thereby, the weight can be reduced by improving the strength of the engaging portion of the convex tooth 21a and the concave groove 22a, the wear resistance can be improved, and the durability can be ensured over a long period of time. It is to be noted that not only the convex surfaces of both the convex teeth 21a and the concave grooves 22a are cured, but only the convex teeth 21a are cured, so that the combined tolerance width of the engaging portion due to heat treatment deformation can be suppressed. An axial clearance δ between the portion 19 and the end face of the caulking portion 6 can be ensured.

  As shown in FIG. 1, the shaft portion 20 of the outer joint member 14 is fitted with the fitting profiles 21 and 22 so that a predetermined axial clearance δ is interposed between the shoulder portion 19 and the end surface of the crimped portion 6. And the fastening bolt 24 is screwed into the female screw 20a of the shaft portion 20 via the washer 23, so that the hub wheel 1 and the outer joint member 14 are coupled to each other so as to be separable in the axial direction. Has been. Here, the axial clearance δ is set to 1 mm or more in consideration of the combined tolerance width of the convex teeth 21a and the concave grooves 22a so that the shoulder portion 19 and the caulking portion 6 do not contact each other. The washer 23 is coated with a seal layer 23a made of an elastomer such as a coating film or rubber. Thereby, the sealing performance in the contact portion between the hub wheel 1 and the washer 23 is improved.

  As described above, the fitting profiles 21 and 22 each have the predetermined pressure angle α and are configured by the convex teeth 21 a and the concave grooves 22 a each having a predetermined inclination angle β in the axial direction with respect to the axial center. In addition, an excessive pressure input is not required, and it is possible to easily obtain a strong fitting state without a backlash in the circumferential direction at the final stage of insertion, and at the engagement portion of the convex teeth 21a and the concave grooves 22a during torque transmission. The generated radially outward component force can be suppressed, and the bearing clearance is not adversely affected. Accordingly, it is possible to realize a strong connection without backlash, to achieve light weight and compactness, and since the axial clearance δ is formed between the shoulder portion 19 and the end face of the crimping portion 6, self-retained The structure can be provided, the bearing preload can be maintained for a long time without firmly tightening the fastening bolt 24, and a stick-slip sound is generated even when a large torque is applied to the outer joint member 14 to cause torsion. It does not occur.

  Furthermore, in the present embodiment, as shown in an enlarged view in FIG. 3, an annular groove 19 a is formed on the outer periphery of the shoulder portion 19, and an elastic ring 25 made of an O-ring or the like is attached to the annular groove 19 a. The opening of the annular space formed between the crimping portion 6 and the crimping portion 6 is liquid-tightly closed. As a result, even if an axial clearance δ is formed between the shoulder 19 and the end face of the caulking portion 6, foreign matters such as rainwater and dust can enter the engaging portions of the convex teeth 21a and the concave grooves 22a. And rusting of the engaging portion can be prevented over a long period of time.

  FIG. 6 is a longitudinal sectional view showing a second embodiment of the bearing device for a drive wheel according to the present invention, and FIG. 7 is an enlarged view of a main part of FIG. In this embodiment, only the fastening portion and the sealing structure are different from those of the first embodiment described above, and other parts having the same parts or the same functions are denoted by the same reference numerals and detailed description thereof is omitted. .

  As in the above-described embodiment, this drive wheel bearing device has a configuration called a third generation in which the hub wheel 1, the double row rolling bearing 2 and the constant velocity universal joint 26 are detachably unitized. . The shaft portion 20 of the outer joint member 27 in the constant velocity universal joint 26 is constituted by a short shaft, and a fitting profile 21 in which a plurality of convex teeth 21a are equally arranged on the outer periphery is formed. Then, a male screw 28 projects from the end of the shaft 20, and the shaft 20 of the outer joint member 27 has a predetermined axial clearance δ between the shoulder 29 and the end surface of the crimped portion 6. Is fitted to the hub wheel 1 via the fitting profiles 21 and 22, and the fixing nut 30 is screwed to the male screw 28 of the shaft portion 20, so that the hub wheel 1 and the outer joint member 27 can be separated in the axial direction. Is bound to.

  An end cap 31 is attached to the outer end of the hub wheel 1 so that the open end of the hub wheel 1 is closed, and as shown in an enlarged view in FIG. Metal fitting (circle portion in the figure) is performed, and the opening portion of the annular space formed between the shoulder portion 29 and the caulking portion 6 is closed. As a result, foreign matter such as rainwater and dust can be prevented from entering the engaging portions of the convex teeth 21a and the concave grooves 22a, and rusting of the engaging portions can be prevented over a long period of time. It is possible to improve the disassembly workability at the time of repair by preventing the engagement portion from being fixed. As shown in the drawing, if the surface of the shoulder portion 29 and the crimping portion 6 is coated with a sealing layer 35 made of an elastomer such as a coating film or rubber, rusting of the crimping portion 6 is prevented and a predetermined amount is obtained. The strength can be secured and the initially set bearing preload can be maintained over a long period of time.

  The embodiment of the present invention has been described above, but the present invention is not limited to such an embodiment, and is merely an example, and various modifications can be made without departing from the scope of the present invention. Of course, the scope of the present invention is indicated by the description of the scope of claims, and further, the equivalent meanings described in the scope of claims and all modifications within the scope of the scope of the present invention are included. Including.

  The drive wheel bearing device according to the present invention is applied to a drive wheel bearing device in which a bearing portion having a hub ring and a constant velocity universal joint are connected so as to be able to transmit torque, and both are detachably unitized by screw means. can do.

It is a longitudinal section showing a 1st embodiment of a bearing device for drive wheels concerning the present invention. (A) is a front view which shows the fitting profile of the axial part of FIG. (B) is a cross-sectional view along the II-II line of (a). It is a principal part enlarged view of FIG. It is a graph which shows the expansion amount of the hub ring with respect to a pressure angle, and the separation force which generate | occur | produces in an engaging part. It is a graph which shows the amount of expansion of a hub ring with respect to an inclination angle, and the separation force which occurs in an engaging part. It is a longitudinal cross-sectional view which shows 2nd Embodiment of the bearing apparatus for drive wheels which concerns on this invention. It is a principal part enlarged view of FIG. It is a longitudinal cross-sectional view which shows the conventional bearing apparatus for drive wheels.

Explanation of symbols

1 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Hub wheel 1a, 5a ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Inner rolling surface 1b ・ ・ ・ ・ ・ ・··· Small diameter step 2 ··························································································・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Wheel mounting flange 4a ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Hub bolt 5 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・... Inner ring 6 ... Caulking part 7 ... Outer member 7a ... Outer rolling surface 7b ... Body mounting flange 8 ... Inner member 9 ... rolling element 10 ... cage 11, 12, ... ···················································································· Outer joint member ..... Joint inner ring 15a, 18a ... Track groove 16 ... Cage 17 ...・ ・ ・ ・ ・ ・ ・ ・ Torque transmission ball 18 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Mouse part 19, 29 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Shoulder Portion 19a ... Annular groove 20 ... Shaft portion 20a ...・ Female thread 21, 22 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Fitting profile 21a ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Convex tooth 22a ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・..Witch 23 ... Washer 23 , 35 ... Seal layer 24 ... Fastening bolt 25 ... Elasticity Ring 28 ... Male thread 30 ... Fixing nut 31 ... .... End caps 32, 33, 34 ... Hardened layer 51 ... Hub wheels 51a, 58a ...・ Inner rolling surface 51b ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Small diameter step portion 51c ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Clamping portion 52 ・ ・ ・ ・ ・ ・ ・ ・.... Double-row rolling bearing 53 ... Constant velocity universal joint 54 ... Wheel mounting Flange 55 ... Outer member 55a ...・ ・ ・ ・ ・ ・ ・ ・ ・ Outer rolling surface 55b ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Car body mounting flange 56 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Rolling element 57 ... inner member 58 ... inner ring 59 ...・ Mouse 60 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Shoulder 61 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Shaft 61a ・ ・ ・ ・ ・ ・.... Screw hole 62 ... Outer joint member 63 ... Female spline 64 ... ········· Male spline 65 ···················································· ............ Retaining ring 68 ..................... Seal ring 69 ······················ Cap 69a ································ Bolt m・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Module d ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Mating profile average diameter z・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Number of teeth or grooves α ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Pressure angle β ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Inclination angle δ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Axial clearance

Claims (5)

An outer member having a double row outer raceway formed on the inner periphery;
A hub wheel integrally having a wheel mounting flange for mounting a wheel at one end and having a cylindrical small-diameter step portion extending in the axial direction on the outer periphery, and at least one press-fitted into the small-diameter step portion of the hub ring An inner member formed of two inner rings and formed with a double-row inner rolling surface facing the double-row outer rolling surface;
A double row rolling element accommodated between the rolling surfaces so as to roll freely;
A constant velocity universal joint, and an outer joint member coupled to the hub wheel through a screw means so as to be separable in the axial direction;
The outer joint member integrally has a cup-shaped mouth portion, a shoulder portion that forms the bottom portion of the mouth portion, and a shaft portion that extends in the axial direction from the shoulder portion, and the shaft portion torques the hub wheel. In the bearing device for the drive wheel fitted through the transmission means,
The torque transmission means corresponds to the fitting profile formed by arranging a plurality of convex teeth on the outer periphery of the shaft portion, and is engaged with the convex teeth on the inner periphery of the hub wheel. And a fitting profile formed by arranging a plurality of concave grooves having a cross-sectional dovetail shape, the convex teeth having a substantially trapezoidal cross section, having a predetermined pressure angle, and having an axial center on the tooth surface In contrast, a predetermined inclination angle is formed in the axial direction, and a predetermined hardened layer is formed in the range of 58 to 64 HRC by surface induction hardening from the shoulder portion to the convex teeth of the shaft portion. A bearing device for a drive wheel characterized by the above.   The drive wheel bearing device according to claim 1, wherein a pressure angle in a tooth surface of the convex teeth and the concave grooves is set in a range of 0 to −30 °.   The bearing device for a drive wheel according to claim 1 or 2, wherein an inclination angle in a tooth surface of the convex tooth and the concave groove is set in a range of 2 to 7 °.   The inner ring is fixed to the hub wheel in the axial direction by a crimping portion formed by plastically deforming the end portion of the small diameter step portion radially outward, and the end surfaces of the shoulder portion and the crimping portion The drive wheel according to any one of claims 1 to 3, wherein a shaft portion of the outer joint member is fitted to the hub wheel via the fitting profile so that a predetermined axial clearance is interposed between the hub wheel and the hub wheel. Bearing device.   The drive wheel bearing device according to any one of claims 1 to 4, wherein a predetermined hardened layer is formed with a surface hardness in a range of 58 to 64 HRC by induction hardening in a concave groove of the fitting profile in the hub wheel.

Images