JP4455182B2 - Wheel bearing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bearing device for a wheel, improving durability by securing appropriate preload during straight running and bearing rigidity during turning. <P>SOLUTION: The bearing device for the wheel has an angular contact ball bearing provided with an outer member 10 in which double row outer rolling faces 10a are formed on the inner periphery, an inner member 1 in which double row inner rolling faces 2a, 3a opposing to the double row outer rolling faces 10a are formed on the outer periphery, and double row balls 6 stored between the outer and inner members 10, 1. At least the inner rolling face 3a is formed to have an arc shape comprising a radius r of curvature formed from the vicinity of a point P contacting with the ball 6 at an contact angle &alpha; over a groove bottom and a radius r1 of curvature formed over outer diameter 3b, and set to be within ranges, 1.05 Da &lt; 2r &le;1.10 Da and 1.01 Da &le; 2r1 &le; 1.05 Da with respect to diameter Da of the ball 6. Therefore, corresponding to running conditions of the wheel, such as straight running and turning, appropriate preload amount can be set. <P>COPYRIGHT: (C)2006,JPO&amp;NCIPI

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 in particular, to ensure an appropriate bearing preload and bearing rigidity according to the traveling state of the vehicle, thereby improving durability. The present invention relates to a wheel bearing device.

  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. These wheel bearing devices are configured by unitizing a hub wheel and a double row rolling bearing. As a typical example, both the inner member and the outer member have a flange integrally. For a wheel referred to as a third generation, in which one inner rolling surface of the rolling bearing is formed directly on the hub wheel and the other inner rolling surface is formed on a separate inner ring press-fitted into the hub wheel. Bearing devices are known.

  FIG. 6 shows a third-generation wheel bearing device on the drive wheel side, which includes an outer member 51, an inner member 52, and a double row of balls 53 accommodated between these members. The inner member 52 integrally has a wheel mounting flange 54 for mounting a wheel (not shown) at one end, an inner rolling surface 55a on the outer periphery, and a cylinder extending in the axial direction from the inner rolling surface 55a. A hub wheel 55 having a small-diameter step portion 55b formed therein, and an inner ring 56 press-fitted into the small-diameter step portion 55b of the hub wheel 55 and having an inner rolling surface 56a formed on the outer periphery. Further, hub bolts 57 for fixing the wheels are implanted at equal circumferential positions of the wheel mounting flanges 54. The inner ring 56 is prevented from coming off in the axial direction with respect to the hub wheel 55 by a crimped portion 55c formed by plastically deforming the end portion of the small diameter step portion 55b of the hub wheel 55 radially outward. .

  The outer member 51 integrally has a vehicle body mounting flange 51b fixed to the suspension device 58 on the outer periphery, and double row outer rolling surfaces 51a, 51a are formed on the inner periphery. The double row balls 53, 53 are interposed between the double row outer raceway surfaces 51a, 51a and the inner raceway surfaces 55a, 56a opposite to the double row outer raceway surfaces 51a, 51a via a cage 59. Is housed in a rollable manner.

  Here, the outer end surface 56b of the inner ring 56 is pushed in the axial direction by the caulking portion 55c, and a predetermined preload is applied to the bearing. A metal ring is provided between the outer end surface 56b of the inner ring 56 and the caulking portion 55c in a state where a required axial clearance 60 is secured between the shoulder portion 55d of the hub ring 55 and the inner end surface 56c of the inner ring 56. 61 is interposed in a state compressed in the axial direction so as to be elastically restored.

The metal ring 61 is made of an iron-based material, and is formed into a shape having a pair of radially outward flanges 61b at both axial end edges of the annular body 61a. In the non-compressed state, no compression force is applied in the axial direction. In a compressed state, the annular main body 61a is curved and deformed so as to be elastically restored radially outward in the range of the elastic deformation region. With this metal ring 61, the preload applied to the bearing can be properly maintained even when the rolling surface is worn, and the load bearing capacity and the life can be ensured.
JP 2002-21847 A

  However, in such a conventional wheel bearing, when a moment load larger than the preload urged by the metal ring 61 is applied to the bearing when the vehicle turns, the initial preload cannot be secured, so-called. It is difficult to obtain the necessary load-bearing capacity, that is, the bearing rigidity, due to the occurrence of preload loss. Therefore, in order to prevent this preload loss, it is necessary to set the initial preload high. In this case, the rigidity of the bearing during turning can be ensured, but the rolling resistance during steady running of the vehicle, i.e., when traveling straight, becomes excessively high, causing an abnormal temperature rise of the bearing, and the preload amount becomes excessive and the bearing There is a risk that the service life will be significantly reduced.

  The present invention has been made in view of such circumstances, and provides a wheel bearing device that secures a proper preload during straight travel and ensures bearing rigidity during turning to improve durability. It is an object.

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 formed on the inner periphery, and an outer rolling surface of these double rows on the outer periphery. For a wheel provided with an inward member formed with opposing double-row inner rolling surfaces, and a double-row ball accommodated so as to roll between the rolling surfaces and provided with a predetermined contact angle. in the bearing device, before Symbol inner rolling run surface curvature are formed over the groove bottom from the vicinity of the contact point in contact with the ball at an initial contact angle and a radius r, said from the vicinity of the contact points A radius of curvature r1 formed over the outer diameter of the rectangular member, and the curvature radii r and r1 are 1.05 Da <2r ≦ 1.10 Da and 1.01 Da with respect to the diameter Da of the ball. ≦ 2r1 ≦ 1.05 Da is set, and the outer rolling surface is from the vicinity of the contact point. A radius of curvature r2 formed over the bottom and a radius of curvature r3 formed over the inner diameter of the outer member from the vicinity of the contact point, where the radius of curvature r2, r3 is 1 0.07 Da <2r2 ≦ 1.12 Da and 1.03 Da ≦ 2r3 ≦ 1.07 Da, and the preload amount is set in the range of 0 to 10 μm when the vehicle goes straight and 10 to 50 μm when turning .

Thus, an outer member having a double row outer rolling surface formed on the inner periphery, and an inner member having a double row inner rolling surface facing the outer rolling surface of these double rows formed on the outer periphery. When, in the wheel bearing device having the angular ball bearings and a ball double row housed between the two members, the inner side rolling run surface, from the vicinity of the contact point which contacts the ball at an initial contact angle A radius of curvature r formed over the groove bottom and a radius of curvature r1 formed over the outer diameter of the inner member from the vicinity of the contact point, and the radius of curvature with respect to the ball diameter Da. r and r1 are set in the range of 1.05 Da <2r ≦ 1.10 Da and 1.01 Da ≦ 2r1 ≦ 1.05 Da, and the outer rolling surface is formed from the vicinity of the contact point to the groove bottom. Radius of curvature r2 and the radius of curvature formed from the vicinity of the contact point to the inner diameter of the outer member 3 and curvature radii r2 and r3 are set in the range of 1.07 Da <2r2 ≦ 1.12 Da and 1.03 Da ≦ 2r3 ≦ 1.07 Da, 0 to 10 μm when the vehicle goes straight, and when turning Since the preload amount is set in the range of 10 to 50 μm, the preload applied at the initial stage is ensured when the vehicle is traveling (straight), and excessive preload is suppressed to prevent an increase in rolling resistance. In addition, the amount of preload can be increased and the bearing rigidity can be increased and the durability can be improved without adding any parts even when the vehicle is turned with a moment load.

According to a second aspect of the present invention, the inner member includes a hub wheel integrally having a wheel mounting flange for mounting a wheel at one end, and an inner ring or a constant velocity universal joint fitted to the hub wheel. Since these members are integrated by plastic bonding, there is no need to control the preload by tightening firmly with a nut or the like as in the prior art, so that the ease of incorporation into the vehicle is simplified. In addition, it is possible to maintain the initially set amount of preload over a long period of time.

The wheel bearing device according to the present invention includes an outer member having a double-row outer rolling surface formed on the inner periphery, and a double-row inner rolling surface facing the outer rolling surface of the double row on the outer periphery. In the wheel bearing device comprising: the formed inner member; and a double row of balls that are rotatably accommodated between the two rolling surfaces and provided with a predetermined contact angle, the inner rolling surface is A radius of curvature r formed from the vicinity of the contact point in contact with the ball at the initial contact angle to the groove bottom, and from the vicinity of the contact point to the outer diameter of the inner member. The curvature radii r and r1 are set in a range of 1.05 Da <2r ≦ 1.10 Da and 1.01 Da ≦ 2r1 ≦ 1.05 Da with respect to the diameter Da of the ball. In addition, the curvature of the outer rolling surface formed from the vicinity of the contact point to the groove bottom is reduced. r2 and a radius of curvature r3 formed from the vicinity of the contact point to the inner diameter of the outer member. The radiuses of curvature r2 and r3 are 1.07 Da <2r2 ≦ 1.12 Da and 1 0.03 Da ≦ 2r3 ≦ 1.07 Da, and the preload amount is set in the range of 0 to 10 μm when the vehicle goes straight and 10 to 50 μm when the vehicle turns. Preload applied to the vehicle is ensured, and excessive preload can be suppressed to prevent an increase in rolling resistance.At the time of turning of a vehicle loaded with moment load, the preload amount is increased accordingly, The bearing rigidity can be increased and durability can be improved without adding.

An outer member having a double row outer raceway formed on the inner circumference, and a wheel mounting flange at one end, and one inner raceway facing the double row outer raceway on the outer circumference. And a hub wheel formed with a cylindrical small-diameter step portion extending in the axial direction from the inner rolling surface, and externally fitted to the small-diameter step portion of the hub wheel, and opposed to the double-row outer rolling surface on the outer periphery. An inner member formed of an inner ring on which the other inner rolling surface is formed, and a double row of balls accommodated in a freely rolling manner between the both rolling surfaces and provided with a predetermined contact angle, In the wheel bearing device in which the inner ring is fixed in the axial direction by a caulking portion formed by plastically deforming an end portion of the small-diameter stepped portion radially outward, the inner rolling surface has an initial contact angle. A radius of curvature r formed from the vicinity of the contact point in contact with the ball to the groove bottom, and from the vicinity of the contact point A radius of curvature r1 formed over the outer diameter of the rectangular member, and the curvature radii r and r1 are 1.05 Da <2r ≦ 1.10 Da and 1.01 Da with respect to the diameter Da of the ball. ≦ 2r1 ≦ 1.05 Da is set, and the outer rolling surface has a radius of curvature r2 formed from the vicinity of the contact point to the groove bottom, and the outward direction from the vicinity of the contact point. A radius of curvature r3 formed over the inner diameter of the member, and the radius of curvature r2 and r3 are set in a range of 1.07 Da <2r2 ≦ 1.12 Da and 1.03 Da ≦ 2r3 ≦ 1.07 Da The preload amount is set in a range of 0 to 10 μm when the vehicle is traveling straight and 10 to 50 μm when the vehicle is turning .

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 explanatory view of the main part of FIG. 1, (a) is when a vehicle goes straight, (b ) Indicates when the vehicle is turning. In the following description, the side closer to the outer side of the vehicle when assembled to the vehicle is referred to as the outboard side (left side in the drawing), and the side closer to the center is referred to as the inboard side (right side in the drawing).

  The wheel bearing device includes an inner member 1, an outer member 10, and double rows of balls 6, 6 accommodated between the members 1, 10 so as to roll freely. The inner member 1 includes a hub ring 2 and a separate inner ring 3 that is externally fitted to the hub ring 2. The hub wheel 2 integrally has a wheel mounting flange 4 for mounting a wheel (not shown) at an end portion on the outboard side, and the wheel is fixed at a circumferentially equidistant position of the wheel mounting flange 4. The hub bolt 5 is planted.

  Further, on the outer periphery of the hub wheel 2, an inner rolling surface 2a and a cylindrical small-diameter step portion 2b extending in the axial direction from the inner rolling surface 2a are formed. The inner ring 3 having the inner raceway surface 3a formed on the outer periphery is press-fitted into the small-diameter step portion 2b, and the end portion of the small-diameter step portion 2b is plastically deformed outward in the radial direction. Thus, the inner ring 3 is prevented from coming off in the axial direction with respect to the hub ring 2. Since this embodiment employs such a self-retain structure, it is not necessary to manage the preload by tightening firmly with a nut or the like as in the prior art, so that the ease of incorporation into the vehicle is simplified. In addition, the preload amount can be maintained for a long time.

  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 a double row outer rolling surface facing the inner rolling surfaces 2a and 3a on the inner periphery. 10a and 10a are formed. The double-row balls 6 and 6 are accommodated in a freely rollable manner via the cages 7 and 7 with a predetermined contact angle α between the rolling surfaces 10a, 2a and 10a and 3a. Yes. Sealing devices 8 and 9 are mounted on the end of the outer member 10 to prevent leakage of lubricating grease sealed inside the bearing and to prevent rainwater and dust from entering the bearing from the outside. is doing.

  The constant velocity universal joint 11 includes an outer joint member 15 that integrally includes a cup-shaped mouth portion 12, a shoulder portion 13 that forms the bottom of the mouth portion 12, and a shaft portion 14 that extends in the axial direction from the shoulder portion 13. . The outer joint member 12 is fitted into the inner member 1 so that torque can be transmitted. That is, a serration (or spline) 16 is formed on the inner periphery of the hub wheel 2, and a serration (or spline) 17 is formed on the outer periphery of the shaft portion 14 of the outer joint member 15, and meshes with the serration 16 of the hub wheel 2. is doing. Then, the shaft portion 14 of the outer joint member 15 is fitted into the hub wheel 2 until the shoulder portion 13 abuts against the caulking portion 2 c of the hub wheel 2, and is fixed to the male screw 18 formed at the end portion of the shaft portion 14. The nut 19 is fastened with a predetermined tightening torque, and the hub wheel 2 and the outer joint member 15 are coupled so as to be axially separable.

  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.

  The hub wheel 2 is formed of medium carbon steel containing carbon of 0.40 to 0.80% by weight such as S53C, and includes an inner rolling surface 2a on the outboard side, a seal land portion to which the seal device 8 is slidably contacted, and The hardened layer 20 is formed in the range of 58 to 64 HRC by induction hardening over the small diameter step portion 2b (indicated by cross hatching in the figure). Such an induction hardening pattern improves the strength of the hub wheel 2 and suppresses fretting on the fitting surface of the inner ring 3 to improve durability. The caulking portion 2c is an unquenched portion having a material surface hardness of 25 HRC or less after forging.

  On the other hand, the inner ring 3 is made of high carbon chrome bearing steel such as SUJ2, and is hardened in the range of 58 to 64 HRC up to the core part by quenching. The outer member 10 is formed of medium carbon steel containing carbon of 0.40 to 0.80% by weight such as S53C, and the double row outer rolling surfaces 10a and 10a have a surface hardness of 58 to 58 by induction hardening. Hardened to a range of 64 HRC.

  In the present embodiment, as shown in an enlarged view in FIG. 2A, the inner raceway surface 3a of the inner ring 3 is formed in an arc shape having two curvature radii. That is, the inner raceway surface 3a of the inner ring 3 has a radius of curvature r formed from the vicinity of the contact point P in contact with the ball 6 at the initial contact angle α to the groove bottom, and from the vicinity of the contact point P. It is comprised with the curvature radius r1 formed over the large outer diameter 3b. The initial contact angle α is appropriately set in the range of 30 to 45 ° depending on the load condition of the vehicle and the bearing space.

  Here, as indicated by hatching in the figure, the curvature radius r is set to be larger than the curvature radius r1, and 1.05 Da <2r ≦ 1.10 Da, preferably 1.05 Da <with respect to the diameter Da of the ball 6. The range is set to 2r ≦ 1.08 Da. The radius of curvature r1 is set to a range of 1.01 Da ≦ 2r1 ≦ 1.05 Da, preferably 1.03 Da ≦ 2r1 ≦ 1.05 Da with respect to the diameter Da of the ball 6. As a result, as shown in FIG. 2 (b), when the vehicle is in steady running (straight forward), the ball 6 contacts the contact point P with a predetermined amount of preload at the initial contact angle α, and the moment load When the vehicle is turned, the ball 6 contacts the contact point P1 at a contact angle α1 with a predetermined preload amount. In addition, although not shown in figure, also in the hub ring 2 which comprises the inner member 1 like the inner ring 3, the inner side rolling surface 2a is formed in the circular arc shape which consists of two curvature radii.

  On the other hand, as shown in FIG. 2A, the outer rolling surface 10a of the outer member 10 is also formed in an arc shape having two curvature radii r2 and r3. That is, the outer rolling surface 10a of the outer member 10 has a radius of curvature r2 formed from the vicinity of the contact point Q that contacts the ball 6 at the initial contact angle α to the groove bottom, and the contact point Q. The radius of curvature r3 is formed from the vicinity to the inner diameter 10c.

  Here, as indicated by hatching in the figure, the radius of curvature r2 is set larger than the radius of curvature r3, and is 1.07 Da <2r2 ≦ 1.12 Da, preferably 1.07 Da <with respect to the diameter Da of the ball 6. The range is set to 2r2 ≦ 1.10 Da. Further, the radius of curvature r3 is set to a range of 1.03 Da ≦ 2r3 ≦ 1.07 Da, preferably 1.05 Da ≦ 2r3 ≦ 1.07 Da with respect to the diameter Da of the ball 6. As a result, as shown in FIG. 2B, when the vehicle is in steady running, the ball 6 and the contact point Q come into contact with each other with a predetermined preload amount at an initial contact angle α, and a moment load is applied. When the vehicle turns, the ball 6 contacts the contact point Q1 at a contact angle α1 with a predetermined preload amount.

  In the present embodiment, at least the inner rolling surface 3a (2a) is formed in an arc shape composed of two curvature radii r and r1, and the respective preload amounts are 0 to 0 when the vehicle travels straight (contact points P and Q). 10 μm is set in a range of 10 to 50 μm at the time of turning (contact points P1, Q1). As a result, during steady running of the vehicle, the preload applied in the initial stage is ensured, and excessive preload can be suppressed to prevent an increase in rolling resistance, and at the time of turning of the vehicle loaded with moment load, Accordingly, the preload amount can be increased, and the bearing rigidity can be increased and the durability can be improved without adding any parts.

  In addition, the thing which comprised the rolling surface of both the double row inner side rolling surfaces 2a and 3a of the inner member 1 and the double row outer side rolling surfaces 10a and 10a of the outer member 10 with two curvature radii, respectively is illustrated. However, it is preferable that the double row inner raceway surfaces 2a and 3a side of the inner member 1 having a strong influence on the bearing rigidity and life at least be configured with these two curvature radii r and r1. Of course, not only two radii of curvature but also a plurality of radii of curvature consisting of three or more radii of curvature can be used to form the connecting portions of the rolling surfaces more smoothly and continuously. An appropriate amount of preload can be set corresponding to the running condition.

  Next, the processing method will be described using the inner raceway surface 3a of the inner ring 3 as an example with reference to FIG. Since the inner rolling surface 3a is composed of a plurality of radii of curvature r and r1, the grinding process is performed by a grinding wheel previously formed into the shape of the inner rolling surface 3a. Can not cope with a conventional grindstone simply by oscillation processing. Therefore, here, it is processed by a so-called elastic grindstone 21 in which abrasive grains are mixed in an elastomer such as rubber and the abrasive grains are exposed on the surface. By subjecting such an elastic grindstone 21 to oscillation along the shape of the inner rolling surface 3a, the elastic grindstone 21 is moderately adapted to the shape of the inner rolling surface 3a composed of a plurality of radii of curvature r and r1. It can deform | transform and can form in a desired finishing surface, without destroying the shape of the inner side rolling surface 3a.

  4A and 4B are explanatory views showing another processing method. FIG. 4A is a plan view and FIG. 4B is a cross-sectional view. As shown in (a), the grindstone 22 formed with a single radius of curvature is inclined at a predetermined angle with respect to the rotation axis of the inner rolling surface (work surface) 3a, and as shown in (b). The grinding wheel 22 is pressed against the inner rolling surface 3a, and the shape of the inner rolling surface 3a is destroyed by oscillating the cross-sectional shape of the processing surface 22a of the grinding wheel 22 corresponding to the shape of the inner rolling surface 3a. It can be formed on the desired finished surface.

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 same components same part as 1st Embodiment, and the detailed description is abbreviate | omitted.
In this wheel bearing device, a hub wheel 23, a double row rolling bearing 24 and a constant velocity universal joint 25 are unitized to form a fourth generation structure. The double row rolling bearing 24 includes an outer member 10, an inner member 26, and double rows of balls 6 and 6.

  The inner member 26 refers to a hub wheel 23 and an outer joint member 27 described later that is fitted into the hub wheel 23. The hub wheel 23 is made of medium carbon steel containing 0.40 to 0.80 wt% of carbon such as S53C, and has an inner rolling surface 23a on the outboard side on the outer periphery and a cylinder extending in the axial direction from the inner rolling surface 23a. A small-diameter step portion 23b is formed, an uneven portion 23c is formed on the inner periphery, and a hardened layer is formed with a surface hardness in the range of 54 to 64 HRC by heat treatment. As the heat treatment, local heating is preferable, and quenching by high-frequency induction heating that can set the hardened layer depth relatively easily is preferable. The concave and convex portion 23c is formed in the shape of an iris knurl, and is a cross groove formed by orthogonally intersecting a plurality of annular grooves formed independently by turning or the like and a plurality of axial grooves formed by broaching or the like. Alternatively, it consists of a cross groove composed of spiral grooves inclined with respect to each other. Further, in order to ensure good biting properties, the tip of the convex portion of the concave and convex portion 23c is formed in a spire shape such as a triangular shape.

  The constant velocity universal joint 25 includes an outer joint member 27, a joint inner ring 28, a cage 29, and a torque transmission ball 30. The outer joint member 27 is made of medium carbon steel containing carbon of 0.40 to 0.80 wt% such as S53C, and has a cup-shaped mouth portion 31, a shoulder portion 32 that forms the bottom portion of the mouth portion 31, and the shoulder portion 32. A cylindrical shaft portion 33 extending in the axial direction from is integrally formed. The shaft portion 33 is formed with an in-row portion 33a that is cylindrically fitted to the small-diameter step portion 23b of the hub wheel 23 through a predetermined radial clearance, and a fitting portion 33b is formed at the end of the in-row portion 33a. .

  An inboard-side inner rolling surface 27a is formed on the outer periphery of the shoulder portion 32, and the surface hardness is hardened to a range of 58 to 64 HRC by induction hardening over the inner rolling surface 27a and the shaft portion 33. A layer is formed. Here, the fitting part 33b is left raw after forging.

  The end surface of the small-diameter step portion 23b of the hub wheel 23 is abutted with the shoulder portion 32 of the outer joint member 27, and the shaft portion 33 is fitted into the hub wheel 23 until it comes into a butted state. Then, a diameter expanding jig such as a mandrel is pushed into the inner diameter of the fitting portion 33b in the shaft portion 33 to increase the diameter of the fitting portion 33b, and the fitting portion 33b is bitten into the uneven portion 23c of the hub wheel 23. By caulking, the hub wheel 23 and the outer joint member 27 are integrally plastically coupled. An end cap 34 is attached to the hollow shaft portion 33 to prevent the grease sealed in the mouth portion 31 from leaking to the outside. Although not shown, an end cap is also attached to the opening end of the hub wheel 23 to prevent rainwater or the like from entering the plastic coupling portion and rusting the portion.

  Also in the present embodiment, as in the above-described embodiments, at least the double-row inner rolling surfaces 2a and 27a of the inner member 26 of the outer member 10 and the inner member 26 are configured with a plurality of curvature radii. As a result, the weight can be further reduced and the size can be reduced, and an appropriate preload amount can be set according to the traveling condition of the vehicle such as when the vehicle is traveling straight and turning, thereby suppressing excessive preload. Thus, an increase in rolling resistance can be prevented, and bearing rigidity can be further increased and durability can be improved without adding any parts.

  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 first-generation to fourth-generation wheel bearing device including an outer member, an inner member, and a double row of balls accommodated between both members.

It is a longitudinal section showing a 1st embodiment of a bearing device for wheels concerning the present invention. FIGS. 2A and 2B are explanatory views enlarging the main part of FIG. 1, in which FIG. 1A shows when the vehicle goes straight, and FIG. 1B shows when the vehicle turns. It is explanatory drawing which shows the processing method of the rolling surface in the wheel bearing apparatus which concerns on this invention. It is explanatory drawing which shows the other processing method of the rolling surface in the wheel bearing apparatus which concerns on this invention, (a) is a top view, (b) is sectional drawing. 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, 26 ... Inner member 2, 23 ... Hub wheels 2a, 3a, 23a, 27a ... Inner rolling surface 2b 23b ... Small diameter step 2c ... Caulking part 3 ... Inner ring 3b ··········· Outer diameter 4 ············ Wheel mounting flange 5 ········ ... Hub bolts 6 ... Rolling elements 7 ... Retainers 8, 9 ...・ ・ ・ ・ ・ ・ Seal 10 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Outer member 10a ・ ・ ・ ・ ・ ・ ・ ・ Outer rolling surface 10b .... Body mounting flange 10c .... Inside diameter 11, 25 ... ... Constant velocity universal joints 12, 31 ... Mouse part 13, 32 ... Shoulder part 14, 33 ... ... Shaft parts 15, 27 ... Outer joint members 16, 17 ... Serration 18 ...・ ・ Male screw 19 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Fixing nut 20 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Hardened layer 21, 22・ Whetstone 22a ・ ・ ・ ・ ・ ・ ・ ・ Processed surface 23c ・ ・ ・ ・ ・ ・ ・ ・ Concavity and convexity 24 ・ ・ ・ ・ ・ ・ ・ ・ ・Rolling bearing 28 of row ·················· Coupling inner ring 29 ······························· .... Torque transmission balls 33a 3b ... fitting part 34 ... end cap 51 ... outside Side member 51a ... Outer rolling surface 51b ... Car body mounting flange 52 ...・ ・ Inner member 53 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Ball 54 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Wheel mounting flange 55 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・・ ・ ・ ・ Hub wheel 55a, 56a ・ ・ ・ ・ ・ ・ Inner rolling surface 55b ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Small diameter step 55c ... Caulking part 55d ... Shoulder part 56 ... Inner ring 56b ... .... Outer end face 56c ... Inner end face 57 ... ... Hub bolts 58 ... Suspension devices 59 ... Retainer 60 ...・ ・ ・ ・ ・ Axial clearance 61 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Metal ring 61a ・ ・ ・ ・ ・ ・ ・ ・ Annular body 61b ・ ・ ・ ・ ・ ・ ・ ・... Flange Da ..... Diameters of balls r, r1, r2, r3 ..... Radius of curvature P, Q, P1, Q1 ... ... Contact points α, α1 ... Contact angle

Claims (2)

An outer member having a double row outer raceway formed on the inner periphery;
An inner member in which a double-row inner rolling surface facing the outer rolling surface of these double rows is formed on the outer periphery;
In a wheel bearing device comprising a double row of balls that are accommodated in a freely rolling manner between the rolling surfaces and provided with a predetermined contact angle,
Outside before Symbol inner rolling run surface curvature are formed over the groove bottom from the vicinity of the contact point in contact with the ball at an initial contact angle and a radius r, the inner member from the vicinity of the contact points A radius of curvature r1 formed over the diameter, and the radius of curvature r, r1 is 1.05 Da <2r ≦ 1.10 Da and 1.01 Da ≦ 2r1 ≦ 1 with respect to the diameter Da of the ball. .05 Da, and the outer rolling surface has a radius of curvature r2 formed from the vicinity of the contact point to the groove bottom, and from the vicinity of the contact point to the inner diameter of the outer member. The curvature radii r2 and r3 are set in a range of 1.07 Da <2r2 ≦ 1.12 Da and 1.03 Da ≦ 2r3 ≦ 1.07 Da. 0-10μm when going straight, when turning Wheel bearing apparatus characterized by preload amount is set to a range of 0～50Myuemu. The inner member is composed of a hub wheel integrally having a wheel mounting flange for mounting a wheel at one end, and an inner ring or a constant velocity universal joint fitted to the hub wheel, and these members are formed by plastic coupling. The wheel bearing device according to claim 1, which is integrated .

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