JP2010014163A - Bearing device for wheel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bearing device for a wheel, which secures the strength of its caulking part and on which the most proper shape of the caulking part is set in accordance with bearing size. <P>SOLUTION: In the wheel bearing device wherein an inner ring 3 is press-fitted to a small-diameter step 2b of a hub wheel 2 and the inner ring 3 is fixed by a caulking part 2c formed by plastically deforming the end toward an outer side in a radial direction, the end of the small-diameter step 2b is formed in a hollow cylindrical part 12 before being caulked. Based on the great end surface 3b of the inner ring 3, when an axial size up to the bottom surface 12a of the cylindrical part 12 is expressed as L1, the axial size up to an intersection P of the line of action S of a ball 6 at the inner side and the small-diameter step 2b as L2, the cross section of the caulking part 2c as A (mm<SP>2</SP>), a basic static rating radial load of a train of balls 6 on the inner side as C0r (kN), and the number of balls 6 as Zi, the shape and dimensions of the caulking part 2c are set so as to satisfy both reference expressions: L2>L1, and 0.672Amin≥C0r×Zi×tanθ+80. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a wheel bearing device for rotatably supporting a wheel of an automobile or the like with respect to a suspension device, in particular, ensuring the strength of the crimping portion and setting the optimum shape of the crimping portion according to the bearing size. The present invention relates to a wheel bearing device.

  2. Description of the Related Art Wheel bearing devices for vehicles such as automobiles include those for driving wheels and those for driven wheels. In particular, a wheel bearing device that rotatably supports a wheel with respect to a suspension device of an automobile has been made lighter and more compact for improving fuel efficiency, not to mention cost reduction. As a typical example of the conventional structure, a wheel bearing device for a driven wheel as shown in FIG. 6 is known.

  This wheel bearing device is called the third generation, and includes a shaft member (hub wheel) 51, an inner ring 52, an outer ring 53, and double-row balls 54, 54. The shaft member 51 integrally has a wheel mounting flange 55 for mounting a wheel (not shown) at one end thereof, an inner rolling surface 51a on the outer periphery, and a small diameter extending in the axial direction from the inner rolling surface 51a. A step portion 51b is formed.

  An inner ring 52 having an inner rolling surface 52a formed on the outer periphery is press-fitted into the small-diameter step portion 51b of the shaft member 51. The inner ring 52 is prevented from coming out of the shaft member 51 in the axial direction by a caulking portion 51c formed by plastically deforming the end portion of the small diameter step portion 51b of the shaft member 51 radially outward. .

  The outer ring 53 integrally has a vehicle body mounting flange 53b on the outer periphery, and double row outer rolling surfaces 53a and 53a are formed on the inner periphery. And the double row balls 54 and 54 roll between the double row outer rolling surfaces 53a and 53a and the inner rolling surfaces 51a and 52a opposite to the double row outer rolling surfaces 53a and 53a. It is freely housed.

  Here, the thickness of the cylindrical portion 56 forming the crimped portion 51c is smaller toward the tip edge before the cylindrical portion 56 is crimped and expanded outward in the radial direction. The thickness of the caulking portion 51c that presses the large end surface 52b of the inner ring 52 is increased with respect to the thickness of the proximal end portion of the cylindrical portion 56 by expanding the cylindrical portion 56 radially outward. It gradually decreases as it goes to.

Thereby, the force required for plastically deforming the distal end portion of the cylindrical portion 56 by the pressing die to form the crimped portion 51c does not increase suddenly, and the crimped portion 51c has a crack or the like accompanying the crimping operation. The inner ring 52 that is damaged or that is fixed by the caulking portion 51c is subjected to a force that greatly changes the diameter of the inner ring 52 so as to affect the durability such as preload and rolling fatigue life. There is no.
Japanese Patent Laid-Open No. 10-272903

  In such a conventional wheel bearing device, the force that greatly deforms the inner diameter of the inner ring 52 is prevented so as to affect the durability such as the preload and the rolling fatigue life accompanying the caulking work. be able to. However, while suppressing the deformation of the inner ring 52, there is a concern that the strength of the caulking portion 51c is insufficient. That is, since the caulking portion 51 applies the axial force (pressing force) of the inner ring 52, the axial force reacts even when there is no load, and the bearing portion has a large vibration and noise. It is necessary to ensure the strength so that at least the caulking portion 51c does not break until it becomes large and cannot be used continuously.

  The present invention has been made in view of such conventional problems, and provides a wheel bearing device in which the strength of the crimped portion is ensured and the optimum shape of the crimped portion is set according to the bearing size. The purpose is to do.

In order to achieve such an object, the invention according to claim 1 of the present invention includes an outer member in which a double row outer rolling surface is integrally formed on the inner periphery, and a wheel for attaching a wheel to one end. A hub wheel integrally having a mounting flange and formed with a small-diameter step portion extending in the axial direction on the outer periphery, and an inner side that is press-fitted into the small-diameter step portion of the hub wheel and faces the outer surface of the double row on the outer periphery. An inner member composed of at least one inner ring formed with a rolling surface, and a double row rolling member accommodated between the rolling surfaces of the inner member and the outer member via a cage. In the wheel bearing device, wherein the inner ring is fixed in the axial direction with respect to the hub wheel by a crimping part formed by plastically deforming the small-diameter step part radially outward. The tensile strength of σk (MPa) and the cross-sectional area of A (mm ² ) Standard equation of σ kmin × Amin = 0.672 Amin ≧ C0r × Zi × tan θ + 80, where C0r (kN) is the basic static rated radial load of the rolling element row on the inner side, Zi is the number of the rolling elements, and θ is the contact angle. And the end of the small-diameter step portion of the hub wheel before caulking is formed in a hollow cylindrical portion, and the axial dimension from the bottom surface of the cylindrical portion to the large end surface of the inner ring is L1, and the inner The shape of the caulking portion is such that L2> L1 is established, where L2 is an axial dimension from the intersection of the line of action of the rolling elements of the rolling element row on the side and the small diameter step portion to the large end surface of the inner ring.・ Dimensions are set.

In this way, the inner ring is fixed in the axial direction with respect to the hub wheel by the crimping part formed by press-fitting the inner ring into the small diameter step part of the hub wheel and plastically deforming the end of the small diameter step part radially outward. In the above-described wheel bearing device, the tensile strength of the caulking portion is σk (MPa), the cross-sectional area is A (mm ² ), and the basic static rated radial load of the inner side rolling element row of the double row rolling element rows Is C0r (kN), the number of rolling elements is Zi, and the contact angle is θ, it satisfies the standard equation of σkmin × Amin = 0.672Amin ≧ C0r × Zi × tan θ + 80, and the hub wheel before caulking The end of the small-diameter step is formed in a hollow cylindrical portion, the axial dimension from the bottom surface of this cylindrical portion to the large end surface of the inner ring is L1, the line of action of the rolling elements in the inner rolling element row, and the small-diameter step When the axial dimension from the point of intersection with the large end surface of the inner ring is L2 , The shape and dimensions of the crimped part are set so that L2> L1 is satisfied, so that the strength of the crimped part is ensured while achieving light weight and compactness, and optimum crimping according to the bearing size is achieved. A wheel bearing device in which the shape of the part is set can be provided.

  Preferably, when the allowable shear stress of the caulking portion is τ, the caulking portion axial sectional area is A1, and the caulking portion height is t, as in the invention described in claim 2, τmin × A1 = If the shape and dimensions of the crimped part are set so as to satisfy the standard expression of 0.605A1 ≧ C0r × Z × tan θ + 80 (kN), the basic static rated radial load C0r is uniformly applied to all rolling elements. Even when applied, the caulking portion is not broken by the axial component force, and sufficient strength of the caulking portion can be ensured.

  Further, as in the invention according to claim 3, when the radial width of the crimped portion is E and the height is t, E / t is set in a range of 0.75 to 1.1. As a result, it is possible to achieve light weight and compactness and to secure a desired crimping strength.

  According to a fourth aspect of the present invention, the end portion of the small-diameter step portion is formed into a hollow cylindrical portion before caulking, and the inner surface thereof gradually increases in diameter toward the end portion. Further, as in the invention according to claim 5, the end portion of the small-diameter step portion is formed into a hollow cylindrical portion before caulking, and the thickness thereof is from the bottom portion. It may be formed substantially uniformly over the end.

  Further, as in the invention described in claim 6, the hub wheel is made of medium-high carbon steel containing 0.40 to 0.80% by weight of carbon, and one of the hub wheels is opposed to the double row outer rolling surface on the outer periphery. An inner rolling surface is directly formed, the surface hardness is set to a range of 58 to 64 HRC by induction hardening from the inner rolling surface to the small diameter step portion, and the caulking portion has a surface hardness after forging. The inner ring is made of high carbon chrome bearing steel and the other inner rolling surface facing the outer rolling surface of the double row is formed on the outer periphery, and the core portion is formed by quenching. If it is hardened in the range of 58 to 64 HRC, the inner diameter of the inner ring is greatly deformed so as to reduce the weight and size, and to affect the durability such as preload and rolling fatigue life accompanying the caulking work. Such a force acting It is possible to stop.

  Further, as in the invention described in claim 7, the pitch circle diameter PCDo of the outer rolling element row is formed to be larger than the pitch circle diameter PCDi of the inner rolling element row (PCDo> PCDi). In addition, if the number of rolling elements Zo of the outer rolling element row is set to be larger than the number of rolling elements Zi of the inner rolling element row (Zo> Zi), the bearing space is effectively utilized. Thus, the bearing rigidity of the outer side portion can be increased compared to the inner side, and the life of the bearing can be extended.

The wheel bearing device according to the present invention integrally has an outer member integrally formed with a double row outer rolling surface on the inner periphery, and a wheel mounting flange for mounting the wheel on one end, and on the outer periphery. A hub wheel having a small-diameter step portion extending in the axial direction, and at least one inner rolling surface that is press-fitted into the small-diameter step portion of the hub wheel and that faces the outer rolling surface of the double row on the outer periphery. An inner member formed of an inner ring, and a double row rolling element that is rotatably accommodated between both rolling surfaces of the inner member and the outer member via a cage, and the small-diameter step portion is provided. In a wheel bearing device in which the inner ring is axially fixed to the hub ring by a caulking portion formed by plastic deformation radially outward, the tensile strength of the caulking portion is σk (MPa), The cross sectional area is A (mm ² ), and the basic static regulation of the inner side rolling element row of the double row rolling element rows. When the rated radial load is C0r (kN), the number of rolling elements is Zi, and the contact angle is θ, the standard equation of σkmin × Amin = 0.672 Amin ≧ C0r × Zi × tan θ + 80 is satisfied and before the caulking An end of the small-diameter step portion of the hub wheel is formed in a hollow cylindrical portion. The axial dimension from the bottom surface of the cylindrical portion to the large end surface of the inner ring is L1, and the rolling elements of the inner rolling element row When the axial dimension from the intersection of the action line and the small diameter step portion to the large end surface of the inner ring is L2, the shape and dimensions of the crimping portion are set so that L2> L1 is established. It is possible to provide a wheel bearing device in which the strength of the caulking portion is ensured while reducing the weight and size, and the optimum shape of the caulking portion is set according to the bearing size.

A vehicle body mounting flange to be attached to the knuckle on the outer periphery, an outer member in which a double row outer rolling surface is integrally formed on the inner periphery, and a wheel mounting flange to mount a wheel on 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. A double row rolling element housed in a rolling manner between the rolling surfaces via a cage, and the hub ring is formed by a caulking portion formed by plastic deformation of the small diameter step portion radially outward. On the other hand, in the wheel bearing device in which the inner ring is fixed in the axial direction, the end of the small diameter step portion is Formed in a hollow cylindrical portion before caulking, with reference to the large end surface of the inner ring, the axial dimension to the bottom surface of the cylindrical portion is L1, and the inner side rolling element in the double row rolling element row L2 is the axial dimension to the intersection of the line of rolling elements of the row and the small diameter step, the cross sectional area of the crimped portion is A (mm ² ), and the basic static rated radial load of the inner rolling element row Is C0r (kN), the number of the rolling elements is Zi, and the contact angle is θ, L2> L1 and the above-mentioned addition is satisfied so that the standard expression of 0.672 Amin ≧ C0r × Zi × tan θ + 80 is satisfied. The shape and dimensions of the fastening part are set.

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, FIG. 2 is an enlarged view of a main part of FIG. 1, and FIG. 3 is an enlarged main part of a modification of FIG. FIG. 4 and FIG. 4 are enlarged views of main parts showing another modification of FIG. In the following description, the side closer to the outer side of the vehicle when assembled to the vehicle is referred to as the outer side (left side in FIG. 1), and the side closer to the center is referred to as the inner side (right side in FIG. 1).

  This wheel bearing device is referred to as the third generation on the driven wheel side, and is a double row rolling element (ball) accommodated between the inner member 1 and the outer member 10 and between both members 1 and 10 so as to roll freely. 6 and 6. The inner member 1 includes a hub ring 2 and an inner ring 3 that is press-fitted into the hub ring 2 through a predetermined scissors.

  The hub wheel 2 integrally has a wheel mounting flange 4 for mounting a wheel (not shown) at an end portion on the outer side, and hub bolts 5 are implanted in the wheel mounting flange 4 at equal intervals in the circumferential direction. At the same time, a circular hole 4 a is formed between the hub bolts 5. This circular hole 4a can not only contribute to weight reduction, but also a fastening jig such as a wrench can be inserted from the circular hole 4a in the assembly / disassembly process of the apparatus, and the work can be simplified. Further, one (outer side) inner rolling surface 2a and an axial small-diameter step portion 2b extending in the axial direction from the inner rolling surface 2a via the shoulder portion 11 are formed on the outer periphery of the hub wheel 2. Yes. And the inner ring | wheel 3 in which the inner side rolling surface 3a of the other (inner side) was formed in the outer periphery is press-fitted in this small diameter step part 2b via predetermined | prescribed shimiro.

  Then, with the small end surface 3c of the inner ring 3 abutted against the shoulder 11 of the hub wheel 2, the end portion of the small diameter step portion 2b is plastically deformed radially outward to form a crimped portion 2c. That is, the inner ring 3 is sandwiched between the caulking portion 2 c and the shoulder portion 11 of the hub wheel 2, and the inner ring 3 is fixed to the hub wheel 2 in the axial direction. The caulking portion 2c is formed by being plastically deformed in close contact with the outer side of the inner ring 3 and can press the large end surface 3b of the inner ring 3 to ensure a desired axial force.

  The outer member 10 integrally has a vehicle body mounting flange 10b for mounting to the vehicle body (not shown) on the outer periphery, and double row outer rolling surfaces 10a, 10a are integrally formed on the inner periphery. And the double row rolling elements 6 and 6 are accommodated between each rolling surface 10a, 2a and 10a, 3a, and these double row rolling elements 6 and 6 are rollably hold | maintained by the holder | retainers 7 and 7. ing. Seals 8 and 9 are attached to the opening of the annular space formed between the outer member 10 and the inner member 1, and leakage of lubricating grease sealed inside the bearing and rainwater and dust from the outside. Etc. are prevented from entering the inside of the bearing.

  Here, the wheel bearing device referred to as the third generation in which the inner raceway surface 2a is formed directly on the outer periphery of the hub wheel 2 is illustrated, but the wheel bearing device according to the present invention is limited to such a structure. For example, a first generation or second generation structure in which a pair of inner rings are press-fitted into a small-diameter step portion of the hub ring may be used. Moreover, although the double row angular contact ball bearing which used the rolling elements 6 and 6 as the ball | bowl was illustrated, it is not restricted to this, The double row tapered roller bearing which uses a tapered roller for a rolling element may be sufficient.

  The hub wheel 2 is made of medium and high carbon steel containing carbon of 0.40 to 0.80% by weight such as S53C, and includes a base portion 4b which becomes a seal land portion of the outer side seal 8 including the inner side rolling surface 2a on the outer side. The surface hardness is set to a range of 58 to 64 HRC by induction hardening over the small diameter step 2b. The caulking portion 2c is an unquenched portion of the material surface hardness after forging.

  On the other hand, the inner ring 3 and the rolling element 6 are made of high carbon chrome bearing steel such as SUJ2, and are hardened in the range of 58 to 64 HRC up to the core by quenching. Similarly to the hub wheel 2, the outer member 10 is made of medium-high carbon steel containing 0.40 to 0.80% by weight of carbon such as S53C, and has high frequency on at least the double row outer rolling surfaces 10a and 10a. The surface hardness is hardened by quenching to a range of 58 to 64 HRC.

Here, the present applicant secures the strength of the caulking portion 2c and sets the optimum shape of the caulking portion 2c according to the bearing size, and the caulking portion for the inner ring 3 and the caulking portion for the inner ring 3. We focused on the relationship between the shape and dimensions of 2c. In this embodiment, as shown in FIG. 2, the end portion of the small-diameter step portion 2b of the hub wheel 2 before caulking is formed as a hollow cylindrical portion 12 (indicated by a two-dot chain line in the figure). In examining the proof strength of the caulking portion 2c, when the outer diameter of the small diameter step portion 2b is D1, and the inner diameter of the inner ring 3 at the position of the large end surface 3b in the caulking portion 2c is D2, the inner diameter of the inner ring 3 is determined at the position of the large end surface 3b. The minimum cross-sectional area Amin (mm ² ) of the caulking portion 2c is Amin = π (D1 ² −D2max ² ) / 4.

  On the other hand, the following formula is known as a formula representing the relationship between hardness and tensile strength (Japanese Standards Association). By citing this equation, the relationship between the surface hardness Hk (Hv) and the tensile strength σk (MPa) of the caulking portion 2c can be expressed by σk = 3.2Hk. Here, when the surface hardness of the caulking portion 2c remains in the range of 13 to 30 HRC with the material surface hardness after forging, the tensile strength σkmin = 3.2Hk = 3.2 × 210 of the caulking portion 2c. (Equivalent to 13HRC) = 672 (MPa).

  Therefore, when the axial force of the inner ring 3, that is, the force that fixes the inner ring 3 by the crimping portion 2 c is F, in addition to this axial force F, the bearing portion has a large vibration and noise that cannot be used continuously. Even if the basic static rated radial load C0r (kN) is uniformly applied to all the balls 6, the tensile strength of the crimped portion 2c is σkmin × What is necessary is just to satisfy the reference formula of Amin ≧ C0r × Z × tan θ + F (kN), and the shape and dimensions of the crimped portion 2c may be set so as to satisfy this reference formula. Accordingly, it is possible to prevent a force that greatly deforms the inner diameter of the inner ring 3 from acting so as to affect the durability such as the preload and the rolling fatigue life accompanying the caulking work, and the caulking portion. 2c can ensure sufficient yield strength. Here, Zi is the number of rolling elements 6 in the inner side bearing row, and θ is the contact angle of the inner side bearing row.

  Generally, in this type of wheel bearing, since the axial force F of the inner ring 3 is set in a range of 20 to 80 kN, F = 80 kN is set to the above-described reference equation, that is, σkmin × Amin ≧ C0r × Zi × tan θ + F. When applied to (kN), it is sufficient to satisfy 0.672 Amin ≧ C0r × Zi × tan θ + 80 (kN) as the tensile strength of the crimped portion 2 c. Furthermore, the axial dimension from the bottom surface 12a of the cylindrical portion 12 before caulking to the large end surface 3b of the inner ring 3 is L1, and the inner ring 3 has a large dimension from the intersection P between the action line S of the inner bearing row and the small diameter step portion 2b. When the axial dimension to the end face 3b is L2, if L2> L1, the caulking process can be easily performed, and the caulking portion 2c is damaged by the caulking work. While being able to prevent, the load applied to a bearing part is not applied to the crimping part 2c, and durability can be improved.

  In this embodiment, in order to ensure the axial force of the inner ring 3 and the tensile strength of the caulking portion 2c at the same time, the tensile strength of the caulking portion 2c determined from the basic static rated radial load C0r of the bearing row on the caulking side is determined. Based on the standard formula, the shape and dimensions of the caulking portion 2c are set, so that a wheel bearing device that achieves light weight and compactness and ensures the axial force of the inner ring 3 and the tensile strength of the caulking portion 2c is provided. Can be provided.

  Here, the end portion of the small-diameter step portion 2b of the hub wheel 2 before caulking is formed as a hollow cylindrical portion 12, and the inner diameter surface thereof is formed into a tapered surface that gradually increases in diameter toward the end portion. However, the shape of the caulking portion 2c according to the present invention is not limited to this, and for example, as shown in FIG. 3, the cylindrical portion 12 'before caulking has a wall thickness from the bottom portion 12a. It may be formed substantially uniformly over the end. Thereby, the process variation of the internal diameter of cylindrical part 12 'can be suppressed, and the intensity | strength of the crimping part 2c can be stabilized.

  Next, even when the basic static rated radial load C0r is uniformly applied to all the rolling elements 6, the axially allowable shear stress of the caulking portion 2c is prevented so that the caulking portion 2c is not broken by the axial component force. Satisfies the standard equation of τmin × A1 = 0.605A1 ≧ C0r × Zi × tan θ + F (kN), and if the shape and size of the crimping portion 2c are set so as to satisfy this standard equation good. As described above, the tensile strength of the crimped portion 2c is determined by σkmin = 3.2Hk = 3.2 × 210 (equivalent to 13HRC), but this part is expected to increase in hardness by about 60Hv by work hardening. Therefore, σkmin = 3.2 × (210 + 60) Hv = 864 (MPa).

  Since the shear stress is generally 70% of the tensile stress, the allowable shear stress τmin = 605 MPa. As shown in FIG. 4, when the height of the crimping portion 2c is t, the axial sectional area A1 = πD1t of the crimping portion 2c is obtained. When the axial force F = 80 kN of the inner ring 3 is applied to the reference equation, that is, τmin × A1 = 0.605A1 ≧ C0r × Zi × tan θ + F (kN) as described above, generally, the shearing force of the caulking portion 2c It is sufficient if the proof stress satisfies 0.605A1 ≧ C0r × Z × tan θ + 80 (kN).

  Further, when a total axial load equivalent to the basic static rated radial load C0r is applied, a force is applied to the outer diameter side of the crimped portion 2c, and the crimped portion 2c is extended in the opening direction. For this reason, since it is necessary to set the radial width E of the caulking portion 2c related to the large end surface 3b of the inner ring 3 and to secure the volume of the caulking portion 2c, the radial direction of the caulking portion 2c By setting the width E and the height of the caulking portion 2c to t as E / t = 0.75 to 1.1, a desired caulking strength can be ensured. Here, when this ratio is small, the crimping strength is insufficient, and when this ratio is large, the volume of the crimping portion 2c is increased, which is not preferable.

  FIG. 5 is a longitudinal sectional view showing a second embodiment of the wheel bearing device according to the present invention. In addition, the same code | symbol is attached | subjected to the component and site | part which has the same component same part as embodiment mentioned above, or the same function, and detailed description is abbreviate | omitted.

  This wheel bearing device is for a driven wheel referred to as a third generation, and is an inner member 13, an outer member 14, and a double row rolling element accommodated between the members 13 and 14 so as to roll freely. 6 and 6 rows. The inner member 13 includes a hub ring 15 and an inner ring 3 press-fitted into the hub ring 15 via a predetermined shimiro.

  The hub wheel 15 integrally has a wheel mounting flange 4 at an end portion on the outer side, one (outer side) inner rolling surface 15a on the outer periphery, and an axial portion extending in the axial direction from the inner rolling surface 15a. A small-diameter step 2 b is formed through 16.

  The inner ring 3 is formed with the other (inner side) inner raceway surface 3a on the outer periphery and is press-fitted into the small-diameter stepped portion 2b of the hub wheel 15 to form a back-to-back type double row angular contact ball bearing. The end portion of 2b is fixed in the axial direction by a crimping portion 2c formed by plastic deformation.

  The hub wheel 15 is made of medium and high carbon steel containing 0.40 to 0.80 wt% of carbon such as S53C, and the inner raceway 15a and the base portion 4b on the inner side of the wheel mounting flange 4 to the small diameter step portion 2b. Thus, the surface hardness is set to a range of 58 to 64 HRC by induction hardening.

  The outer member 14 integrally has a vehicle body mounting flange 10 b on the outer periphery, and has an outer outer rolling surface 14 a facing the inner rolling surface 15 a of the hub wheel 15 on the inner periphery, and an inner rolling surface of the inner ring 3. An inner side outer rolling surface 10a facing 3a is integrally formed. Double-row rolling elements 6 and 6 are accommodated between these rolling surfaces and are held by the cages 17 and 7 so as to be freely rollable.

  This outer member 14 is formed of medium and high carbon steel containing 0.40 to 0.80 wt% of carbon such as S53C, and the double row outer rolling surfaces 14a and 10a have a surface hardness in the range of 58 to 64HRC by induction hardening. Has been cured. Seals 18 and 9 are attached to the opening of the annular space formed between the outer member 14 and the inner member 13, and leakage of grease sealed inside the bearing and rainwater from the outside. And dust are prevented from entering the bearing.

  In the present embodiment, the pitch circle diameter PCDo of the outer three rolling elements is set to be larger than the pitch circle diameter PCDi of the inner three rolling elements (PCDo> PCDi). The sizes of the rolling elements 3 are the same, but due to the difference in the pitch circle diameters PCDo and PCDi, the number of rolling elements Zo in the outer three rolling elements is greater than the number of rolling elements Zi in the inner three rolling elements. Are also set (Zo> Zi).

  The outer shape of the hub wheel 15 is such that the counter part 15b from the groove bottom part of the inner rolling surface 15a, the shaft-like part 16 extending in the axial direction from the counter part 15b via the arc-shaped step part 16a, and the inner ring 3 project. It continues to the small diameter step 2b through the shoulder 11 to be fitted. A mortar-shaped recess 19 is formed at the outer end of the hub wheel 15. The depth of the recess 19 is a depth to the vicinity of the groove bottom of the inner rolling surface 15a, and the outer end of the hub wheel 15 is formed to have a substantially uniform thickness. With the difference in pitch circle diameters PCDo and PCDi, the inner rolling surface 15a of the hub wheel 15 is formed to have a larger diameter than the inner rolling surface 3a of the inner ring 3, and the outer diameter of the shaft-shaped portion 16 is increased to the inner rolling surface. The diameter is substantially the same as the groove bottom diameter of the running surface 3a.

  On the other hand, in the outer member 14, the outer side outer rolling surface 14a is formed with a larger diameter than the inner side outer rolling surface 10a in accordance with the difference in pitch circle diameters PCDo and PCDi, and the outer side outer rolling surface 10a is formed. From the running surface 14a through the cylindrical shoulder portion 20 and the tapered step portion 20a to the shoulder portion 21 on the small diameter side, the outer rolling surface 10a on the inner side is reached. And it forms so that the groove bottom diameter of this outer side rolling surface 10a and the internal diameter of the shoulder part 20 by the side of a large diameter may become substantially the same diameter.

  In the wheel bearing device having such a configuration, the pitch circle diameter PCDo of the three outer rolling elements is formed larger than the pitch circle diameter PCDi of the three inner rolling elements, and the number of the rolling elements is accordingly increased. Since the number of rolling elements Zo of the three rolling elements on the side is set to be larger than the number of rolling elements Zi of the three rolling elements on the inner side, the bearings on the outer side portion are effectively utilized compared to the inner side by utilizing the bearing space. The rigidity can be increased and the life of the bearing can be extended. Further, the recess 19 is formed in the outer end portion of the hub wheel 15 along the outer shape, and the outer end portion of the hub wheel 15 is set to have a uniform thickness. And the conflicting problem of high rigidity can be solved.

  Here, in this embodiment, as in the first embodiment described above, the tensile strength of the crimped portion 2c is 0.672 Amin ≧ C0r × Zi × tan θ + 80 (kN), and the cylindrical portion 12 before crimping The axial dimension from the bottom surface 12a to the large end surface 3b of the inner ring 3 is smaller than the axial dimension L2 from the bottom surface 12a to the large end surface 3b of the inner ring 3. Since the shape and dimensions of the caulking portion 2c are set so that the bearing becomes larger, it is possible to effectively utilize the bearing space and increase the bearing rigidity of the outer side portion compared to the inner side, thus extending the life of the bearing. In addition, it is possible to provide a wheel bearing device in which the optimum shape of the caulking portion 2c corresponding to the bearing size is set while ensuring the strength of the caulking portion 2c.

  Further, the height t of the crimping portion 2c is set so as to satisfy 0.605A1 ≧ C0r × Zi × tan θ + 80 (kN) as the shear strength of the crimping portion 2c, and the radial direction of the crimping portion 2c is set. Since the width E and the height of the caulking portion 2c are set in the range of E / t = 0.75 to 1.1, the weight and the size are reduced, and a desired caulking strength is secured. be able to.

  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.

  In the wheel bearing device according to the present invention, the inner ring is fixed by a caulking portion formed by press-fitting an inner ring into a small-diameter step portion of a hub wheel and plastically deforming an end portion of the small-diameter step portion. It can be applied to a self-retained wheel bearing device.

It is a longitudinal section showing a 1st embodiment of a bearing device for wheels concerning the present invention. It is a principal part enlarged view of FIG. It is a principal part enlarged view which shows the modification of FIG. It is a principal part enlarged view which shows the other modification 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 a longitudinal cross-sectional view which shows the conventional wheel bearing apparatus.

Explanation of symbols

1, 13 ... Inner member 2, 15 ... Hub wheels 2a, 3a, 15a Inner rolling surface 2b ... Small diameter step 2c ... ············································································································ Small edge surface 4 Wheel mounting flange 4a ... Circular hole 4b ... Base 5 ... Hub bolt 6 ... Rolling elements 7, 17 ·········· Retainer 8, 9, 18 ··· Seals 10 and 14 · · · Outer members 10a and 14a · · · Outer rolling surface 10b ············ Body mounting flange 11, 20, 21... Shoulder portion 12, 12 ′... Cylindrical portion 15 b... Counter portion 16... Shaft portion 16 a, 20 a. ......... Recess 51 ... ... Hub wheels 51a, 52a ... Inner rolling surface 51b ... Small diameter step 51c ... Clamping part 52 ... Inner ring 52b ...・ ・ ・ ・ ・ Large end surface 53 ・ ・ ・ ・ ・ ・ ・ ・ Outer ring 53a ・ ・ ・ ・ ・ ・ Outside rolling surface 53b ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Car body mounting flange 54 ・ ・ ・ ・ ・ ・ ・ ・ Ball 55 ········ Wheel mounting flange 56 ································· Cross sectional area A1 Axial cross-sectional area C0r ... Basic static rated radial load D1 ... Small diameter step outer diameter D2 ... Large inner ring in the caulking section Inner diameter F at the end face position ······ Axial force Hk of the inner ring ···· Surface hardness L1 ·································· Dimension L from the bottom surface of the inner ring to the large end surface of the inner ring・ ・ ・ ・ ・ ・ ・ ・ Dimension P from the intersection of the action line and the small diameter step to the large end face of the inner ring ・ ・ ・ ・ ・ ・ ・ ・ Intersection between the action line of the inner bearing row and the small diameter step S ... Action line Zi of inner side bearing row ... ... Number of rolling elements Zo of inner side bearing row ... Outer side bearing row The number of rolling elements of θ ·············· Contact angle σk of the inner side bearing row ··································· Allowable shear stress

Claims (7)

An outer member in which a double row outer rolling surface is integrally formed on the inner periphery;
A hub wheel integrally having a wheel mounting flange for mounting a wheel at one end, a small diameter step portion extending in the axial direction on the outer periphery, and a small diameter step portion of the hub wheel are press-fitted, and the double row is disposed on the outer periphery. An inner member composed of at least one inner ring formed with an inner rolling surface facing the outer rolling surface of
A double-row rolling element accommodated between the rolling surfaces of the inner member and the outer member via a cage so as to freely roll,
In the wheel bearing device in which the inner ring is fixed in the axial direction with respect to the hub wheel by a caulking part formed by plastically deforming the small diameter step part radially outwardly,
The tensile strength of the caulking portion is σk (MPa), the cross-sectional area is A (mm ² ), the basic static rated radial load of the inner rolling element row of the double row rolling element rows is C0r (kN), When the number of the rolling elements is Zi and the contact angle is θ, the standard equation of σkmin × Amin = 0.672 Amin ≧ C0r × Zi × tan θ + 80 is satisfied,
The end portion of the small diameter step portion of the hub wheel before caulking is formed in a hollow cylindrical portion, and the axial dimension from the bottom surface of the cylindrical portion to the large end surface of the inner ring is L1, and the inner rolling element row The shape and dimensions of the caulking portion are set so that L2> L1 is established, where L2 is the axial dimension from the intersection of the line of action of the rolling element and the small diameter step portion to the large end surface of the inner ring. A bearing device for a wheel.   The standard of τmin × A1 = 0.605A1 ≧ C0r × Z × tan θ + 80 (kN), where τ is the allowable shear stress of the caulking portion, A1 is the axial sectional area of the caulking portion, and t is the height of the caulking portion. The wheel bearing device according to claim 1, wherein the shape and dimensions of the caulking portion are set so as to satisfy the equation.   3. The wheel bearing device according to claim 1, wherein E is set to a range of E / t = 0.75 to 1.1, where E is a radial width of the caulking portion and t is a height. .   The end portion of the small-diameter step portion is formed in a hollow cylindrical portion before caulking, and the inner diameter surface thereof is formed in a tapered surface that gradually increases in diameter toward the end portion. The wheel bearing device described.   The end portion of the small diameter step portion is formed in a hollow cylindrical portion before caulking, and the thickness thereof is formed substantially uniformly from the bottom portion to the end portion. Wheel bearing device.   The hub wheel is made of medium-high carbon steel containing carbon of 0.40 to 0.80% by weight, and one inner rolling surface facing the outer rolling surface of the double row is directly formed on the outer periphery. The surface hardness is set to a range of 58 to 64 HRC by induction hardening from the surface to the small diameter step portion, and the caulking portion is an unquenched portion having a material surface hardness of 30 HRC or less after forging, and the inner ring Is made of high carbon chrome bearing steel, the other inner rolling surface facing the outer rolling surface of the double row is formed on the outer periphery, and is hardened in the range of 58 to 64 HRC to the core part by quenching. Item 6. A wheel bearing device according to any one of Items 1 to 5.   A pitch circle diameter PCDo of the outer rolling element row is formed to be larger than a pitch circle diameter PCDi of the inner rolling element row (PCDo> PCDi), and the outer rolling element row rolling element is formed. 7. The wheel bearing device according to claim 1, wherein the number Zo is set to be greater than the number of rolling elements Zi in the inner-side rolling element array (Zo> Zi).

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