JP2009079654A - Wheel bearing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lightweight and compact wheel bearing device capable of securing a sufficient axial force and the strength of a caulking part. <P>SOLUTION: In the wheel bearing device wherein an inner ring 3 is press-fitted to a small diameter step 2b and the inner ring 3 is fixed by a caulking part 2c which are formed by plastically deforming the tip of the small diameter step 2b toward an outer side in a radial direction, the end of the small diameter step 2b is formed in a hollow cylindrical 12 before being caulked. Based on the great end face 3b of the inner ring 3, when an axial size to the bottom face 12a of the cylindrical 12 is expressed as L1: the axial size to an intersection point P where a line of action of a bearing train at the inner side and the small diameter step 2b cross each other as L2, the cross-sectioned area of the caulking part 2c as A(mm<SP>2</SP>): a basic static rating radial load of the bearing train at the inner side as COr(kN), and the number of ball 6 of the bearing train at the inner side as Z, the shape and size of the caulking part 2c is set so as to satisfy both reference expressions: L2>L1 and 0.672Amin≥0.84COr×Z+80. <P>COPYRIGHT: (C)2009,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, and more particularly to a wheel bearing that achieves a light weight and a compact size while ensuring axial force of an inner ring and proof strength of a caulking portion. It relates to the device.

  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. 4 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 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 crimped 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. Even if a large, unusable load, the so-called static load rating C0, is uniformly applied to all the balls 54, it is necessary to ensure the strength so that the caulking portion 51c is not broken by the axial component force.

  The present invention has been made in view of such a conventional problem, and aims to provide a wheel bearing device that achieves a light weight and a compact size while ensuring the axial force of the inner ring and the proof strength of the caulking portion. To do.

In order to achieve such an object, the invention according to claim 1 of the present invention is such that an outer member in which a double row outer rolling surface is integrally formed on the inner periphery and a wheel mounting flange at one end are integrated. A hub wheel having a small-diameter step portion extending in the axial direction on the outer periphery, and an inner rolling surface that is press-fitted into the small-diameter step portion of the hub wheel and faces the outer rolling surface of the double row on the outer periphery. An inner member composed of at least one inner ring, and a double row rolling element accommodated between the rolling surfaces of the inner member and the outer member via a cage. In a 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 outward, the tensile strength of the caulking part is increased. σk (MPa), cross-sectional area of crimped part A (mm ² ), basic static rating radial load of inner side bearing row When the weight is C0r (kN), the number of rolling elements of the inner side bearing row is Z, the contact angle of the inner side bearing row is α, and the axial force of the inner ring is F (kN), σkmin × Amin ≧ C0r The shape and dimensions of the caulking portion are set so as to satisfy the standard expression of × Z × tan α + F.

  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 wheel bearing device thus constructed, the tensile strength of the caulking portion is σk, the cross-sectional area of the caulking portion is A, the basic static radial load of the inner side bearing row is C0r, and the rolling elements of the inner side bearing row are When the number is Z, the contact angle of the inner bearing row is α, and the axial force of the inner ring is F, the shape and the shape of the caulking portion are set so as to satisfy the standard formula of σkmin × Amin ≧ C0r × Z × tan α + F. Since the dimensions are set, it is possible to provide a wheel bearing device that achieves light weight and compactness, and also ensures the axial force of the inner ring and the proof strength of the caulking portion.

  Preferably, if 0.672 Amin ≧ 0.84 C0r × Z + 80 is satisfied as in the invention described in claim 2, the sufficient crimping portion has sufficient proof strength, and the fracture of the crimping portion is surely prevented. can do.

  According to a third aspect of the present invention, the end portion of the small diameter step portion is formed in a hollow cylindrical portion before caulking, and the bottom surface of the cylindrical portion is based on the large end surface of the inner ring. If the dimension in the axial direction up to L1 and the dimension in the axial direction to the intersection of the action line of the inner bearing row and the small-diameter step portion is L2, if L2> L1, the caulking process is easy In addition, it is possible to prevent the caulking part from being damaged such as cracks during caulking work, and the load applied to the bearing part is not applied to the caulking part, and durability is improved. Can be improved.

  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 outer surface of the double row 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 influence the durability such as preload and rolling fatigue life accompanying the caulking work. Such a force acting It is possible to stop.

The wheel bearing device according to the present invention has an outer member in which a double row outer rolling surface is integrally formed on the inner periphery, a wheel mounting flange on one end, and a small diameter extending in the axial direction on the outer periphery. An inner ring comprising a hub ring formed with a stepped portion and at least one inner ring press-fitted into a small-diameter stepped portion of the hub ring and having an inner rolling surface opposed to the outer rolling surface of the double row on the outer periphery. And a double row rolling element that is rotatably accommodated between the rolling surfaces of the inner member and the outer member via a cage, and the small-diameter step portion is radially outward. 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, the tensile strength of the caulking portion is σk (MPa), and the caulking portion is cut off. The area is A (mm ² ), the inner static bearing radial load is C0r (kN), the inner When the number of rolling elements in the side bearing row is Z, the contact angle of the inner side bearing row is α, and the axial force of the inner ring is F (kN), the standard equation of σ kmin × Amin ≧ C0r × Z × tan α + F Since the shape and dimensions of the caulking portion are set so as to satisfy, it is possible to provide a wheel bearing device that achieves light weight and compactness and secures the axial force of the inner ring and the proof strength of the caulking portion. it can.

An outer member integrally having a vehicle body mounting flange on the outer periphery, an outer member formed integrally with a double row outer rolling surface on the inner periphery, a wheel mounting flange integrally on one end, and the double row on the outer periphery. One inner rolling surface facing the outer rolling surface, 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, and An inner member composed of an inner ring formed with the other inner rolling surface opposite to the double row outer rolling surface, and a roller is interposed between both rolling surfaces of the inner member and the outer member via a cage. The inner ring is fixed in the axial direction with respect to the hub ring by a caulking portion formed by plastically deforming the small-diameter step portion radially outward. In the wheel bearing device, an end portion of the small diameter step portion is formed in a hollow cylindrical portion before caulking, and the inner ring With reference to the end face, the axial dimension to the bottom surface of the cylindrical portion is L1, the axial dimension to the intersection of the action line of the inner bearing row and the small diameter step portion is L2, and the cross-sectional area of the caulking portion A2 (mm ² ), the basic static rated radial load of the inner side bearing row is C0r (kN), the number of rolling elements in the inner side bearing row is Z, L2> L1, and The shape and dimensions of the caulking portion are set so as to satisfy the standard expression of 672Amin ≧ 0.84C0r × Z + 80.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a longitudinal sectional view showing an embodiment of a wheel bearing device according to the present invention, and FIG. 2 is an enlarged view of a main part 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 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 on the outer side, and a hub bolt for fixing the wheel at a circumferentially equidistant position of the wheel mounting flange 4. 5 is planted. 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 by which the inner side rolling surface 3a of the other (inner side) was formed in the outer periphery is press-fit in this small diameter step part 2b.

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 the 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 a vehicle body (not shown) on the outer periphery, and double row outer rolling surfaces 10a, 10a are 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 0.40 to 0.80% by weight of carbon, such as S53C, and the inner diameter rolling surface 2a on the outer side as well as the seal land portion where the seal 8 is in sliding contact with the small diameter step portion 2b. On the other hand, the surface hardness is set to a range of 58 to 64 HRC by induction hardening (indicated by cross hatching in the figure). 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 paid attention to the relationship between the axial force of the inner ring 3 and the shape and dimensions of the caulking portion 2c in order to ensure the axial force of the inner ring 3 and at the same time to ensure the proof stress of the caulking portion 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 of the caulking portion 2c is D2, the position at the position of the large end surface 3b of the inner ring 3 is determined. 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, since the material is broken when a tensile test is performed, an indirect mechanical property evaluation is performed by a hardness test in which the impression is not conspicuous in the test of the mechanical properties of the actual product. The following formulas are known as formulas representing strength relationships (Japan 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 × It suffices to satisfy the standard expression of Amin ≧ C0r × Z × tan α + F (kN), and the shape and dimensions of the crimped portion 2c may be set so as to satisfy this standard expression. 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, Z is the number of rolling elements 6 in the inner side bearing row, and α is the contact angle of the inner side bearing row.

  Generally, in this type of wheel bearing, since the contact angle α is set to 30 to 40 ° and the axial force F of the inner ring 3 is set to a range of 20 to 80 kN, α = 40 ° and F = 80 kN are described above. When applied to the standard equation, that is, σkmin × Amin ≧ C0r × Z × tanα + F (kN), it is sufficient if the tensile strength of the crimped portion 2c satisfies 0.672Amin ≧ 0.84C0r × Z + 80 (kN). 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.

  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 one embodiment of a wheel bearing device 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 longitudinal cross-sectional view which shows the conventional wheel bearing apparatus.

Explanation of symbols

1 ... inner member 2 ... hub wheels 2a, 3a ... inner rolling surface 2b ... small diameter step 2c ······················································································································ Small edge surface 4 ··· Wheel mounting flange 5 ······································································· ··· Seal 10 · · · Outer member 10a · · · Outer rolling surface 10b · · · Body mounting flange 11 ··· Shoulder 12 , 12 '... ··· Cylindrical portion 51 ············· Hub wheels 51a, 52a ··· Inner rolling surface 51b ········ Small diameter step portion 51c ··· Tightening part 52 ... Inner ring 52b ... Large end face 53 .... Outer ring 53a ... Outer rolling surface 53b ... Body mounting flange 54 ... Ball 55 ... Wheel mounting flange 56 ···················· Cross sectional area C0r ·························· .... Outer diameter D2 of the small diameter step ... Inner diameter F at the position of the large end face of the inner ring at the crimped part ... ... Axial force Hk of the inner ring ... ..Surface hardness L1 of the caulking part .... Dimension L2 from the bottom surface of the cylindrical part before caulking to the large end face of the inner ring. Dimension P from the intersection of the inner ring to the large end face of the inner ring ·················· S Line of action Z ... Contact angle .sigma.k ········ tensile strength of the crimp portion of the rolling element number alpha ········· inner side of the bearing column of ... inner side of the bearing column

Claims (6)

An outer member in which a double row outer rolling surface is integrally formed on the inner periphery;
A hub wheel having a wheel mounting flange integrally formed at one end and a small-diameter step portion extending in the axial direction on the outer periphery, and a press-fitted into the small-diameter step portion of the hub wheel, and the outer surface of the double row on the outer periphery. An inner member composed of at least one inner ring formed with an inner rolling surface opposed to
A double row rolling element that is accommodated so as to roll freely between the rolling surfaces of the inner member and the outer member via a cage,
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 of the caulking portion is A (mm ² ), the basic static radial load of the inner side bearing row is C0r (kN), and the inner side bearing row Assuming that the number of rolling elements is Z, the contact angle of the inner side bearing row is α, and the axial force of the inner ring is F (kN), so as to satisfy the standard formula of σkmin × Amin ≧ C0r × Z × tan α + F. A wheel bearing device in which the shape and dimensions of the caulking portion are set.   The wheel bearing device according to claim 1, wherein 0.672 Amin ≧ 0.84 C0r × Z + 80 is established.   The end portion of the small diameter step portion is formed in a hollow cylindrical portion before caulking, and the axial dimension to the bottom surface of the cylindrical portion with reference to the large end surface of the inner ring is L1, and the inner side bearing row 3. The wheel bearing device according to claim 1, wherein L2> L1 is set, where L2 is an axial dimension up to the intersection of the action line and the small diameter step portion.   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.

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