JP4034799B2 - Wheel bearing device - Google Patents

Description

  The present invention relates to a wheel bearing device that rotatably supports a wheel of an automobile or the like, and more particularly to a wheel bearing device that achieves light weight as well as higher rigidity and longer bearing life.

  2. Description of the Related Art Conventionally, a wheel bearing device for supporting a wheel of an automobile or the like is such that a hub wheel for mounting a wheel is rotatably supported via a rolling bearing, and there are a drive wheel and a driven wheel. For structural reasons, an inner ring rotation method is generally used for driving wheels, and an inner ring rotation method and an outer ring rotation method are generally used for driven wheels. As the wheel bearing device, a double-row angular ball bearing having a desired bearing rigidity, exhibiting durability against misalignment, and having a small rotational torque from the viewpoint of improving fuel efficiency is often used. In this double row angular contact ball bearing, a plurality of balls are interposed between a fixed ring and a rotating ring, and a predetermined contact angle is given to the balls so as to contact the fixed ring and the rotating ring.

  Further, the wheel bearing device has a structure called a first generation in which a wheel bearing composed of a double row angular ball bearing or the like is fitted between a knuckle and a hub wheel constituting a suspension device. Second generation structure in which body mounting flange or wheel mounting flange is formed directly on the outer periphery of the member, third generation structure in which one inner rolling surface is directly formed on the outer periphery of the hub wheel, or hub wheel, etc. It is roughly classified into a fourth generation structure in which the inner rolling surface is directly formed on the outer periphery of the outer joint member of the speed universal joint.

  In such a wheel bearing device, conventionally, both rows of bearings have the same specification, so that they have sufficient rigidity when stationary, but the optimum rigidity is not always obtained when the vehicle turns. That is, the position of the vehicle weight when stationary is determined so that it acts on the approximate center of the double row rolling bearing, but when turning, the opposite side of the turning direction (when turning right, the vehicle A large radial load or axial load is applied to the left axle. Therefore, at the time of turning, it is effective to increase the rigidity of the outer bearing row rather than the inner bearing row. Therefore, a wheel bearing device shown in FIG. 5 is known as a wheel bearing device that has improved rigidity during turning without increasing the size of the device.

  This wheel bearing device 50 has a vehicle body mounting flange 51c integrally attached to a knuckle (not shown) on the outer periphery, and an outer side in which double row outer rolling surfaces 51a and 51b are formed on the inner periphery. A member 51 and a wheel mounting flange 53 for mounting a wheel (not shown) at one end are integrally formed, and one inner rolling surface 52a facing the double row outer rolling surfaces 51a and 51b on the outer periphery. The hub wheel 52 formed with a small diameter step portion 52b extending in the axial direction from the inner rolling surface 52a and the small diameter step portion 52b of the hub wheel 52 are externally fitted to the double row outer rolling surface 51a, 51b. An inner member 55 composed of an inner ring 54 formed with the other inner rolling surface 54a facing each other, double rows of balls 56, 57 accommodated between both rolling surfaces, and these double rows of balls 56, 57 A retainer 58 for freely rolling It is composed of a double row angular contact ball bearing with a 9.

  The inner ring 54 is fixed in the axial direction by a caulking portion 52c formed by plastically deforming a small diameter step portion 52b of the hub wheel 52 radially outward. Seals 60 and 61 are attached to the opening of the annular space formed between the outer member 51 and the inner member 55, leakage of the lubricating grease sealed inside the bearing, and rainwater from the outside into the bearing. And dust are prevented from entering.

Here, the pitch circle diameter D1 of the outer side ball 56 is set to be larger than the pitch circle diameter D2 of the inner side ball 57. Along with this, the inner rolling surface 52a of the hub wheel 52 is expanded in diameter than the inner rolling surface 54a of the inner ring 54, and the outer rolling surface 51a on the outer side of the outer member 51 is also rolled on the inner side. The diameter is larger than that of the surface 51b. The outer side balls 56 are accommodated more than the inner side balls 57. As described above, by setting the pitch circle diameters D1 and D2 to D1> D2, the rigidity is improved not only when the vehicle is stationary but also when turning, and the life of the wheel bearing device 50 can be extended. it can.
JP 2004-108449 A

  In such a conventional wheel bearing device 50, the pitch circle diameter D1 of the outer ball 56 is set to be larger than the pitch circle diameter D2 of the inner ball 57, and accordingly, the inner rolling of the hub wheel 52 is performed. The surface 52a is larger in diameter than the inner rolling surface 54a of the inner ring 54. As a result, the rigidity of the outer bearing row can be improved, and the life of the wheel bearing device 50 can be extended. In particular, in the hub wheel 52 to which a bending moment load is applied via the wheel mounting flange 53, Since the inner side rolling surface 52a on the outer side is formed to be larger in diameter than the inner side rolling surface 54a on the inner side, it is formed between the inner side rolling surface 52a on the outer side and the inner side rolling surface 54a on the inner side. A bending stress is repeatedly generated in the stepped portion 62. Such bending stress concentrates on the corners 62a and 62b where the cross section is rapidly reduced in diameter and becomes excessive stress, which may impair the strength and durability of the hub wheel 52.

  The present invention has been made in view of such circumstances, and provides a wheel bearing device that simultaneously solves the conflicting problems of lightweight, compact and high rigidity of the device, and has improved strength and durability. The purpose is to do.

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. A hub wheel integrally formed and having one inner rolling surface opposed to the double-row outer rolling surface on the outer periphery, and a small-diameter step portion extending in the axial direction from the inner rolling surface, and the hub wheel An inner member formed of an inner ring that is press-fitted into a small-diameter step portion and has the other inner rolling surface facing the outer rolling surface of the double row on the outer periphery, and both the inner member and the outer member. In a wheel bearing device including a double row ball accommodated so as to be able to roll between rolling surfaces, a pitch circle diameter of an outer side ball of the double row balls is a pitch circle diameter of an inner side ball. It is set to be larger in diameter than a cylindrical shape from outer raceway surfaces of the outer side of the outer member Following the shoulder on the small diameter side through the shoulder on the large diameter side and the stepped portion, an outer rolling surface on the inner side is formed, the groove bottom diameter of this outer rolling surface and the inner diameter of the shoulder on the large diameter side Are set to substantially the same diameter, and a predetermined hardened layer is continuously formed by induction hardening from the outer outer rolling surface of the outer side to the outer rolling surface of the inner side, and the outer side of the hub wheel A recess formed in the end of the hub ring, and a shaft-like portion extending in the axial direction from the groove bottom portion of the inner raceway surface of the hub wheel and a taper between the inner raceway surface and the small diameter step portion of the hub wheel. A stepped portion is formed, and the outer diameter of the shaft-shaped portion is set larger than the groove bottom diameter of the inner raceway surface of the inner ring, and extends from the inner raceway surface to the smaller diameter step portion. Thus, a predetermined hardened layer is continuously formed by induction hardening.

As described above, in the third-generation wheel bearing device having the hub wheel that is configured by the double row angular ball bearing and integrally has the wheel mounting flange at one end, the outer side ball among the double row balls The pitch circle diameter of the outer member is set to be larger than the pitch circle diameter of the ball on the inner side, and the diameter is reduced from the outer rolling surface on the outer side of the outer member through the shoulder and step on the cylindrical larger diameter side. The outer rolling surface on the inner side is formed following the shoulder on the outer side, the groove bottom diameter of this outer rolling surface and the inner diameter of the shoulder on the larger diameter side are set to substantially the same diameter, and outer outer rolling on the outer side A predetermined hardened layer is continuously formed by induction hardening over the outer rolling surface on the inner side from the surface, and a recess is formed on the outer end of the hub wheel, and the inner side of the hub wheel. Axial from the groove bottom of the inner raceway surface of the hub wheel between the raceway and the small diameter step A shaft-shaped portion and a tapered step portion are formed, and the outer diameter of the shaft-shaped portion is set larger than the groove bottom diameter of the inner raceway surface of the inner ring. As a result, a predetermined hardened layer is continuously formed by induction hardening, thus simultaneously solving the conflicting issues of lighter weight, compactness and higher rigidity, and improved strength and durability. A bearing device can be provided.

  Preferably, as in the invention described in claim 2, if the outer diameters of the double row balls are the same and the number of balls on the outer side is set larger than the number of balls on the inner side, Desired bearing life can be ensured while achieving high rigidity.

Further, as in the invention according to claim 3, the thickness of the ball in the contact angle direction on the inner rolling surface of the hub wheel is in a range of 0.2 to 0.3 of the ball contact diameter of the hub wheel. If set, weight reduction can be achieved while securing the strength and rigidity of the hub wheel corresponding to the use conditions.

Further, as in the invention described in claim 4 , the ratio d / PCDi of the outer diameter d of the ball to the pitch circle diameter PCDi of the inner side ball is 0.14 ≦ (d / PCDi) ≦ 0.25. If it is prescribed | regulated in the range of this, bearing life can be ensured, achieving high rigidity.

The wheel bearing device 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 the outer periphery includes One inner rolling surface facing the outer rolling surface of the row, a hub wheel formed with a small-diameter step portion extending in the axial direction from the inner rolling surface, and a small-diameter step portion of the hub wheel are press-fitted into the outer periphery. An inner member formed of an inner ring formed with the other inner rolling surface opposite to the double row outer rolling surface, and freely rollable between both rolling surfaces of the inner member and the outer member. And a predetermined hardened layer is formed by induction quenching from the inner rolling surface of the hub wheel to the small diameter step portion from the inner base portion of the wheel mounting flange. In the wheel bearing device, the outer side ball pin of the double row balls Ji diameter is set greater than the pitch circle diameter of the inner side of the ball, the small diameter of outer raceway surfaces of the outer side of the outer member via a shoulder portion and a stepped portion of the cylindrical large-diameter The outer rolling surface on the inner side is formed following the shoulder portion on the side, and the groove bottom diameter of the outer rolling surface and the inner diameter of the shoulder portion on the large diameter side are set to substantially the same diameter, and the outer side on the outer side A predetermined hardened layer is continuously formed by induction hardening from the rolling surface to the outer side rolling surface on the inner side , and a recess is formed at the outer side end of the hub wheel, and Between the inner raceway surface of the hub wheel and the small diameter step portion, an axial portion and a tapered step portion extending in the axial direction from the groove bottom portion of the inner raceway surface of the hub wheel are formed. The outer diameter is set to be larger than the groove bottom diameter of the inner raceway surface of the inner ring. Because the prescribed hardened layer is continuously formed by induction hardening, the wheel bearing device has improved the strength and durability while simultaneously solving the conflicting issues of lightening, compactness and high rigidity of the device. Can be provided.

A body mounting flange for mounting to the knuckle on the outer periphery is integrated, an outer member with a double row outer raceway formed on the inner periphery, and a wheel mounting flange for mounting the wheel on one end is integrated. A hub wheel having one inner rolling surface facing the outer rolling surface of the double row on the outer periphery, a small diameter step portion extending in the axial direction from the inner rolling surface, and a small diameter of the hub wheel An inner member consisting of an inner ring that is press-fitted into a stepped portion and has the other inner rolling surface facing the outer rolling surface of the double row on the outer periphery, and both rolling of the inner member and the outer member A plurality of balls that are rotatably accommodated between the surfaces, and the inner ring is connected to the hub ring by a caulking part formed by plastically deforming an end of the small diameter step part radially outward. In the wheel bearing device fixed in the axial direction, the outer side of the double row balls Pitch diameter Lumpur is set greater than the pitch circle diameter of the inner side of the ball, the shoulder portion and the stepped portion of the large-diameter side from the outer side of the outer raceway surfaces cylindrical in the outer member An outer rolling surface on the inner side is formed following the shoulder portion on the small diameter side, and the groove bottom diameter of the outer rolling surface and the inner diameter of the shoulder portion on the large diameter side are set to be substantially the same diameter. A predetermined hardened layer is continuously formed by induction quenching from the outer rolling surface on the side to the outer rolling surface on the inner side, and a recess is formed at the outer end of the hub wheel, And, between the inner raceway surface of the hub wheel and the small diameter step portion, an axial portion and a tapered step portion extending in the axial direction from the groove bottom portion of the inner raceway surface of the hub wheel are formed, and the shaft The outer diameter of the shape portion is set larger than the groove bottom diameter of the inner raceway surface of the inner ring, and the smaller diameter from the inner raceway surface. Predetermined hardened layer is continuously formed by high frequency induction quenching over the stepped portion.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a longitudinal sectional view showing a first embodiment of a wheel bearing device according to the present invention, and FIG. 2 is an enlarged sectional view of the hub wheel of FIG. 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 wheel bearing device is for a driven wheel called a third generation, and includes an inner member 1, an outer member 2, and a double row of balls 3 accommodated between the members 1 and 2 so as to roll freely. 3 are provided. The inner member 1 includes a hub ring 4 and an inner ring 5 press-fitted into the hub ring 4 through a predetermined shimiro.

  The hub wheel 4 integrally has a wheel mounting flange 6 for mounting a wheel (not shown) at one end, and has one (outer side) inner rolling surface 4a on the outer periphery, and the inner rolling surface 4a. A small-diameter step 4b is formed through a tapered step 11a and a shaft 11b extending in the axial direction from the groove bottom, and a shoulder 12 against which the inner ring 5 is abutted. Hub bolts 6a are implanted in the wheel mounting flange 6 in, for example, a circumferentially equal distribution, and a circular hole 6b may be formed between the hub bolts 6a. The circular hole 6b can not only contribute to weight reduction, but also a fastening jig such as a wrench can be inserted from the circular hole 6b in the assembly / disassembly process of the apparatus, and the work can be simplified.

  The inner ring 5 is formed by forming the other (inner side) inner rolling surface 5a on the outer periphery and press-fitting into the small-diameter step portion 4b of the hub wheel 4 and plastically deforming the end portion of the small-diameter step portion 4b. It is fixed in the axial direction by the caulking portion 4c. The inner ring 5 is made of high carbon chrome steel such as SUJ2, and is hardened in the range of 58 to 64 HRC up to the core part by quenching.

  The outer member 2 integrally has a vehicle body mounting flange 2c to be attached to a knuckle (not shown) on the outer periphery, and the outer side outer rolling facing the inner rolling surface 4a of the hub wheel 4 on the inner periphery. The surface 2a and the inner side outer rolling surface 2b facing the inner rolling surface 5a of the inner ring 5 are integrally formed. Double-row balls 3 and 3 are accommodated between these rolling surfaces, and are held by the cages 7 and 7 so as to be freely rollable. A predetermined contact angle α (α = 30 to 40 °) is given to the double row balls 3 and 3 to constitute a back-to-back type double row angular ball bearing.

  A seal 8 is attached to the outer side end of the annular space formed between the outer member 2 and the inner member 1, and the inner side end (inner ring 5) is used to detect the rotational speed of the wheel. The magnetic encoder 9 is fixed, and a cap (not shown) that covers the open end of the outer member 2 is attached. The seal 8 and the cap prevent leakage of grease sealed inside the bearing and intrusion of rainwater, dust, and the like from the outside into the bearing.

  In the present embodiment, the pitch circle diameter PCDo of the outer side ball 3 is set larger than the pitch circle diameter PCDi of the inner side ball 3. The outer diameter d of the double-row balls 3 and 3 is the same, but the number of outer-side balls 3 is set larger than the number of inner-side balls 3 due to the difference in pitch circle diameters PCDo and PCDi. ing. A small-diameter step portion 4b is provided on the outer periphery of the hub wheel 4 via a counter portion 10 that gradually decreases in diameter from the inner rolling surface 4a toward the inner side, a step portion 11 and a shoulder portion 12 where the inner ring 5 abuts. Is formed. The step portion 11 includes a taper portion 11 a that is reduced in diameter from the counter portion 10 toward the inner side, and a shaft-like portion 11 b that is formed between the taper portion 11 a and the shoulder portion 12. With the difference in pitch circle diameters PCDo and PCDi, the inner raceway surface 4a of the hub wheel 4 is enlarged in diameter than the inner raceway surface 5a of the inner race 5, and the groove bottom diameter of the inner raceway surface 5a and the shaft shape are increased. The outer diameter of the part 11b is set to substantially the same dimension.

  The hub wheel 4 is formed of medium carbon steel containing carbon of 0.40 to 0.80 wt% such as S53C, and includes a base portion 6c on the inner side of the wheel mounting flange 6 and an inner rolling surface 4a, and a step portion from the counter portion 10 11 and a predetermined hardened layer (indicated by cross-hatching) 13 within a range of 58 to 64 HRC by induction hardening over the small diameter step portion 4b through the shoulder 12 where the inner ring 5 is abutted. It is formed continuously. The caulking portion 4c is kept in the surface hardness after forging. With such a heat pattern, the wear resistance of the base portion 6 c serving as the seal land portion and the fretting resistance of the small diameter step portion 4 b serving as the fitting portion of the inner ring 5 are improved, and the hub wheel 4 is connected via the wheel mounting flange 6. Even when a bending moment load is repeatedly applied, sufficient mechanical strength and durability can be exhibited.

  On the other hand, in the outer member 2, with the difference in pitch circle diameters PCDo and PCDi, the outer-side outer rolling surface 2a has a diameter larger than the inner-side outer rolling surface 2b, and the outer-side outer rolling surface 2a. The outer side rolling surface 2b on the inner side is formed following the shoulder portion 16 on the small diameter side through the cylindrical shoulder portion 14 and the step portion 15. The groove bottom diameter of the outer rolling surface 2b and the inner diameter of the shoulder 14 on the large diameter side are set to be approximately the same size.

  The outer member 2 is made of medium carbon steel containing carbon of 0.40 to 0.80 wt%, such as S53C, and has a cylindrical shoulder portion 14, a step portion 15 and a small diameter side shoulder from the outer rolling surface 2 a on the outer side. A predetermined hardened layer (shown by cross-hatching in the figure) 17 is continuously formed in the range of 58 to 64 HRC by induction hardening over the outer side rolling surface 2b on the inner side through the portion 16. ing. With such a heat pattern, even if a bending moment load is repeatedly applied to the outer member 2, sufficient mechanical strength and durability can be exhibited.

  In the present embodiment, the ratio d / PCDi of the outer diameter d of the ball 3 to the pitch circle diameter PCDi of the inner ball 3 is improved within a predetermined range after improving the bearing rigidity of the outer side portion. It is specified in the range of 0.14 ≦ (d / PCDi) ≦ 0.25. That is, even if the pitch circle diameter PCDi is the same, the bearing rigidity is increased by reducing the outer diameter d of the balls 3 and increasing the number thereof, so that the smaller the outer diameter d of the balls 3 is from the viewpoint of rigidity. It is preferred. However, since the rolling fatigue life decreases as the outer diameter d of the ball 3 decreases, it is preferable that the outer diameter d of the ball 3 is larger from the viewpoint of life. Here, when the relationship between the pitch circle diameter PCDi and the outer diameter d of the ball 3 is obtained by FEM analysis (analysis by the finite element method), when d / PCDi exceeds 0.25, the wheel bearing device is rigid. Does not improve. On the other hand, it was found that when d / PCDi is less than 0.14, the rolling fatigue life is insufficient as a wheel bearing device. Therefore, the pitch circle diameter PCDo of the outer side ball 3 is increased to improve the bearing rigidity of the outer side portion, and the relationship between the pitch circle diameter PCDi of the inner side ball 3 and the outer diameter d of the ball 3 is increased. Is defined in the range of 0.14 ≦ (d / PCDi) ≦ 0.25, the bearing life can be ensured while achieving high rigidity.

  In addition, a mortar-shaped recess 18 is formed at the outer end of the hub wheel 4 by forging. The depth of the recess 18 extends to the vicinity of the groove bottom of the inner side rolling surface 4a on the outer side, and follows the outer shape of the hub wheel 4 so that the thickness of the outer side of the hub wheel 4 is substantially uniform. The shape corresponding to that is formed. When a moment load is applied to the wheel mounting flange 6, it is considered that the hub wheel 4 is deformed starting from the contact angle α of the outer-side ball 3. The thickness is formed in a predetermined range.

  As shown in an enlarged view in FIG. 2, the base portion 6c of the wheel mounting flange 6 serving as a seal land portion is formed in an arc surface having a predetermined radius of curvature. The minimum thickness t1 of the base portion 6c and its portion As a result of obtaining the rigidity of the hub wheel 4 by the FEM analysis from the relationship with the diameter d1 of the hub, by setting the minimum wall thickness t1 in the range of 0.2 ≦ t1 / d1 ≦ 0.3, the hub corresponding to the use condition Weight reduction can be achieved while securing the rigidity of the wheel 4. That is, when the minimum thickness t1 of the base portion 6c is less than 20% of the diameter d1 of the portion, the deformation becomes large and desired rigidity cannot be obtained. On the other hand, even if the minimum thickness t1 exceeds 30% of the diameter d1, a significant increase in rigidity is not recognized, which is unfavorable because it causes a weight increase. Further, the minimum thickness t1 of the base portion 6c is set to be twice or more the hardened layer depth of the hardened layer 13 in order to prevent burning cracks. Here, the hardened layer depth is set in a range of 2 to 5 mm (about 3.5 mm).

  Similarly to the base portion 6c of the wheel mounting flange 6, the relationship between the wall thickness t2 of the ball 3 on the inner rolling surface 4a in the contact angle α direction and the diameter (ball contact diameter) d2 of the portion is also 0.2 ≦ In the range of t2 / d2 ≦ 0.3, the thickness t2 is set to be twice or more the hardened layer depth.

  In the wheel bearing device having such a configuration, the pitch circle diameter PCDo of the outer side ball 3 is set to be larger than the pitch circle diameter PCDi of the inner side ball 3, and the number of the balls 3 is also equal to the number of the outer side. Therefore, the bearing rigidity of the outer side portion is increased compared to the inner side, and the life of the bearing can be extended. Further, a recess 18 is formed at the outer side end portion of the hub wheel 4 along the outline shape of the hub wheel 4, and the outer wall thicknesses t1 and t2 of the hub wheel 4 are set within a predetermined range. Since the hardened layer 13 is continuously formed from the base portion 6c of the hub wheel 4 through the step portion 11 to the small-diameter step portion 4b, the device can be made lighter, more compact, and higher. It is possible to provide a wheel bearing device that simultaneously solves the conflicting problem of rigidity and that has improved strength and durability.

  FIG. 3 is a longitudinal sectional view showing a second embodiment of the wheel bearing device according to the present invention, and FIG. 4 is an enlarged sectional view of the hub wheel of FIG. Note that this embodiment basically differs from the above-described embodiment (FIG. 1) only in the configuration of the hub wheel, and the same reference numerals are given to other identical parts, identical parts, or parts having the same function. In addition, the detailed description is omitted.

  This wheel bearing device is for a driven wheel called the third generation, and includes an inner member 19 and an outer member 2, and a double row of balls 3 accommodated between the members 19 and 2 so as to roll freely. 3 are provided. The inner member 19 includes a hub ring 20 and an inner ring 5 that is press-fitted into the hub ring 20 via a predetermined scissors.

  A deeper recess 21 than the aforementioned mortar-shaped recess 18 (shown by a two-dot chain line) is formed at the outer end of the hub wheel 20 along the outer shell shape of the hub wheel 20. Further, a small diameter step is provided on the outer periphery of the hub wheel 20 via a shaft-like portion 22 extending in the axial direction from the groove bottom portion of the inner rolling surface 4a, a tapered step portion 23, and a shoulder portion 12 with which the inner ring 5 is abutted. Part 4b is formed. And with the difference in pitch circle diameters PCDo and PCDi, the inner raceway surface 4a of the hub wheel 20 is expanded in diameter than the inner raceway surface 5a of the inner race 5, and the outer diameter of the shaft portion 22 is the inner raceway surface. The diameter is set larger than the groove bottom diameter of 5a.

  The depth of the recess 21 is a depth that extends beyond the groove bottom portion of the inner rolling surface 4a to the vicinity of the step portion 23, and is formed so that the thickness of the outer side of the hub wheel 20 is substantially uniform. . That is, as shown in an enlarged view in FIG. 4, in this embodiment, the minimum thickness t1 of the base portion 6c of the wheel mounting flange 6 serving as the seal land portion and the thickness t2 in the contact angle α direction on the inner rolling surface 4a are as follows. The inner wall surface 4a is set to be larger than the minimum thickness (thickness at the groove bottom diameter d0 position) t0, and, similarly to the above-described embodiment, the minimum thickness t1 of the base portion 6c and the contact angle α direction. The wall thickness t2 is set to be within a range of 0.2 to 0.3 of the diameters d1 and d2 of the portions and at least twice the depth of the hardened layer 13. Further, since the thickness t3 of the bottom of the recess 21 is formed substantially the same as the thicknesses t1 and t2 on the outer side from the contact angle α, the rigidity of the hub wheel 20 is ensured and further weight reduction is achieved. Can be achieved.

  The hub wheel 20 is made of medium carbon steel containing carbon of 0.40 to 0.80 wt% such as S53C, and includes a base portion 6c on the inner side of the wheel mounting flange 6 and an inner rolling surface 4a, and a step portion from the shaft portion 22. A predetermined hardened layer (shown by cross-hatching) 24 is continuously formed in a range of 58 to 64 HRC by induction hardening over the small diameter step portion 4b through the shoulder portion 23 and the shoulder portion 12. Yes. With such a heat pattern, sufficient mechanical strength and durability are exhibited even when a bending moment load is repeatedly applied to the hub wheel 20 having the step portion 23 via the wheel mounting flange 6 as in the above-described embodiment. Can do.

  In the above-described embodiment, the double row balls 3 and 3 have the same outer diameter d, but the outer diameters d of the balls 3 and 3 may be different. For example, the ball 3 arranged on the outer side may be made smaller in outer diameter d than the ball 3 arranged on the inner side, and the number of balls may be set larger.

  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 wheel bearing device according to the present invention can be applied to a wheel bearing device on the driven wheel side of the third generation structure.

It is a longitudinal section showing a 1st embodiment of a bearing device for wheels concerning the present invention. It is an expanded sectional view of the hub ring of FIG. It is a longitudinal cross-sectional view which shows 2nd Embodiment of the wheel bearing apparatus which concerns on this invention. It is an expanded sectional view of the hub wheel of FIG. It is a longitudinal cross-sectional view which shows the conventional wheel bearing apparatus.

Explanation of symbols

1, 19 ... Inner member 2 ... Outer member 3 ...・ ・ ・ ・ ・ ・ Ball 4, 20 ・ ・ ・ ・ ・ ・ ・ ・ Hub wheel 4a, 5a ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Inner rolling surface 4b ・ ・ ・········ Small diameter step 4c ······························· 5 6 ... Wheel mounting flange 6a ... Hub bolt 6b ... ... Circle 6c ... Base 7 ... Cage 8 ... ... Seal 9 ... Magnetic encoder 10 ... Count Portions 11, 15 ......... Steps 11a, 23 ...... Tapered portions 11b, 22 ...... Shaft Parts 12, 14, 16... Shoulder parts 13, 17, 24... Cured layer 18, 21. 50 ... Bearing device for wheel 51 ... Outer member 51a ... .... Outer side outer rolling surface 51b ......... Inner side outer rolling surface 51c ... Flange 52 ·············· Hub rings 52a, 54a ······ Inner rolling surface 52b ...・ Small-diameter stepped portion 52c ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Clamping portion 53 ・ ・..... Wheel mounting flange 54 ..... Inner ring 55 ..... inward Member 56, 57 ... Ball 58, 59 ... Retainer 60, 61 ... Seal 62 ... Steps 62a, 62b ... Corner d ... Ball outer diameter d0 ············· Groove bottom diameter d1 of the rolling surface on the outer side ... Diameter d2 of the minimum thickness part at the base part ... Ball contact diameter D1 at the inner rolling surface on the outer side ...・ Pitch circle diameter D2 of the ball on the outer side ...・ ・ ・ ・ ・ ・ Pitch circle diameter of the inner side ball PCDo ・ ・ ・ ・ ・ ・ ・ ・ Pitch circle diameter of the outer side ball PCDi ・ ・ ・ ・ ・ ・ ・ ・Pitch circle diameter t0 of the ball on the inner side ..... Thickness t1 of the groove bottom on the inner rolling surface on the outer side ... ... Minimum thickness t2 of the base part ..... Thickness t3 in the contact angle direction on the inner rolling surface ...・ Thickness α of the bottom of the recess ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Contact angle

Claims (4)

An outer member having a double row outer raceway formed on the inner periphery;
A wheel mounting flange for mounting a wheel at one end is integrally formed, one inner rolling surface facing the outer rolling surface of the double row on the outer periphery, and a small diameter step extending in the axial direction from the inner rolling surface An inner member comprising a hub wheel formed with a portion, and an inner ring press-fitted into a small-diameter step portion of the hub wheel and having the other inner rolling surface opposed to the outer rolling surface of the double row on the outer periphery. ,
In the wheel bearing device comprising this inner member and a double row of balls accommodated so as to roll between both rolling surfaces of the outer member,
Of the double row balls, the pitch circle diameter of the outer side balls is set to be larger than the pitch circle diameter of the inner side balls, and the outer side outer rolling surface of the outer member has a large cylindrical shape. Following the shoulder on the small diameter side via the shoulder and step on the diameter side, an outer rolling surface on the inner side is formed, and the groove bottom diameter of the outer rolling surface and the inner diameter of the shoulder on the large diameter side are A predetermined hardened layer is continuously formed by induction quenching from the outer outer rolling surface of the outer side to the outer rolling surface of the inner side, and the outer side of the hub wheel. A recess is formed at the end, and between the inner raceway surface of the hub wheel and the small-diameter step portion, an axial portion and a taper shape extending in the axial direction from the groove bottom of the inner raceway surface of the hub wheel The outer diameter of the shaft-shaped portion is set larger than the groove bottom diameter of the inner raceway surface of the inner ring. And which, wheel bearing apparatus characterized by a predetermined hardened layer by induction hardening from the inner raceway surface over the cylindrical portion are formed continuously.   The wheel bearing device according to claim 1, wherein the outer diameters of the double row balls are the same, and the number of the outer side balls is set to be larger than the number of the inner side balls.   The wheel according to claim 1 or 2, wherein a thickness of a ball in a contact angle direction of a ball on an inner rolling surface of the hub wheel is set in a range of 0.2 to 0.3 of a ball contact diameter of the hub wheel. Bearing device. The ratio d / PCDi of the outer diameter d of the ball to the pitch circle diameter PCDi of the inner side ball is defined in a range of 0.14 ≦ (d / PCDi) ≦ 0.25. A wheel bearing device according to claim 1.

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