JP2024119687A - Wheel bearing device - Google Patents

Abstract

[Problem] To provide a wheel bearing device capable of applying sufficient preload inside the bearing. [Solution] The wheel bearing device 1 comprises an outer ring 2, an inner member consisting of a hub ring 3 and an inner ring 4, a wheel bearing 10 consisting of double rows of balls 7, and a constant velocity universal joint 20 having a mouth portion 26 in which track grooves 25 are formed and a stem portion 27 that can be fitted into a through hole 3e of the hub ring 3, and the contact position 43 of the inner raceway surface 4a is located on the outer diameter side of the groove bottom 25a of the track groove 25, and the inner ring 4 is fitted into the small diameter step portion 3a of the hub ring 3. The big end 4B has an inner ring fitting portion 4A that is fitted to the hub wheel 3, an outer side end face 4c that comes into contact with the hub wheel 3, an inner circumferential surface 42 that is located on the inner side of the inner ring fitting portion 4A and has a larger diameter than the inner circumferential surface 41 of the inner ring fitting portion 4A, and an inner ring side abutment surface 4d that is located on the inner diameter side of the inner circumferential surface 42 and against which the mouth portion 26 abuts, the inner ring side abutment surface 4d being a surface perpendicular to the axial direction and the area of the inner ring side abutment surface 4d being larger than the area of the outer side end face 4c.

Description

The present invention relates to a wheel bearing device.

As disclosed in Patent Document 1, a wheel bearing device is known that includes a wheel bearing that rotatably supports the wheels in a suspension system of an automobile or the like, and a constant velocity universal joint that is connected to the wheel bearing so that torque can be transmitted.

The constant velocity joint receives driving force from the vehicle's drive source, but in recent years, there has been a trend toward an increase in electric vehicles in order to prevent global warming and achieve carbon neutrality.

Therefore, Patent Document 1 discloses a configuration in which the inner raceway surface of the inner ring is positioned on the outer diameter side of the track groove of the mouth part of the constant velocity universal joint, and the distance between the flange surface of the hub wheel and the center of rotation of the mouth part relative to the shaft of the constant velocity universal joint is reduced, thereby narrowing the wheel bearing device in the axial direction.

In a wheel bearing device configured in this way, the inner raceway surface of the inner ring is located on the outer diameter side of the track groove of the mouth portion, and a contact surface against which the mouse portion contacts from the inner side is provided on the inner diameter side of the inner raceway surface of the inner ring. When the mouse portion contacts the contact surface of the inner ring, it presses the inner ring in the axial direction, applying a preload to the inside of the wheel bearing.

International Publication No. 2021/148675

However, in the wheel bearing device shown in Fig. 1A of Patent Document 1, the contact surface of the inner ring with the mouth part is small. Also, in the wheel bearing device shown in Figs. 2 and 3 of Patent Document 1, the contact surface of the inner ring with the mouth part is inclined in a direction perpendicular to the axial direction, so the axial pressing force of the mouth part against the inner ring is distributed to the outer diameter side, and a force is applied to the inner ring in a direction that expands the diameter of the inner ring.

In this way, if the contact surface of the inner ring with the mouth portion is small or inclined relative to the direction perpendicular to the axial direction, sufficient preload is not applied inside the bearing, causing the inner ring to creep against the hub ring and risking fretting wear on the mating surface between the inner ring and hub ring. If fretting wear occurs on the mating surface between the inner ring and hub ring, wear debris caused by fretting wear may flow into the outer raceway surface of the hub ring, causing poor lubrication on the outer raceway surface.

The present invention was made in consideration of the above situation, and provides a wheel bearing device in which the inner raceway surface of the inner ring is located on the outer diameter side of the track groove of the mouth portion, and which is capable of applying sufficient preload inside the bearing.

That is, the wheel bearing device is a wheel bearing comprising an outer member having a double-row outer raceway surface on its inner circumference, a hub ring having a wheel mounting flange for mounting a wheel at one axial end, a small diameter step extending axially on its outer circumference, and a through hole penetrating axially in its inner diameter portion, and at least one inner ring fitted into the small diameter step of the hub ring, an inner member having a double-row inner raceway surface facing the double-row outer raceway surface, and double-row rolling elements accommodated in a rollable manner between both the raceway surfaces of the outer member and the inner member, and a constant velocity universal joint having a mouth portion having track grooves formed on its inner circumference surface and a fitting portion extending axially from the mouth portion and capable of fitting into the through hole of the hub ring from the other axial side. A device in which the contact position between the inner raceway surface on the other axial side of the inner member and the rolling element is located on the outer diameter side of the groove bottom of the track groove in the mouth portion, and the inner ring has an inner ring fitting portion that fits into the small diameter step of the hub wheel, a first abutment surface that is located at one axial end of the inner ring fitting portion and abuts against the hub wheel from the other axial side, a big end that is located on the other axial side of the inner ring fitting portion and has a second inner circumferential surface with a larger diameter than the first inner circumferential surface of the inner ring fitting portion, and a second abutment surface that is located on the inner diameter side of the second inner circumferential surface of the big end and abuts against the mouse portion from the other axial side, the second abutment surface is a surface perpendicular to the axial direction, and the area of the second abutment surface is larger than the area of the first abutment surface.

According to the present invention, the pressing force from the mouth part can be reliably applied to the inner ring in the axial direction, and sufficient preload can be applied inside the wheel bearing.

1 is a side cross-sectional view showing a wheel bearing device. 4 is a side cross-sectional view showing the wheel bearing device in a state in which the tip portion of the stem portion is inserted into a through hole of the hub wheel. FIG. 3A is a side cross-sectional view showing a state in which the second protrusion of the stem portion is fitted into the recess of the hub wheel, and FIG. 3B is a cross-sectional view taken along the line AA of FIG. 3A. 4(a) is a side cross-sectional view showing a state in which a first protrusion of the stem portion is press-fitted into a recess of the hub wheel, and FIG. 4(b) is a cross-sectional view taken along line BB of FIG. 4(a). 4 is a side cross-sectional view showing the relationship between an inner ring and a mouth portion in a wheel bearing device. FIG. FIG. 4 is a side cross-sectional view showing a gap between a big end of the inner ring and the mouth portion.

Below, the embodiment of the present invention will be explained with reference to the attached drawings.

[Wheel bearing device]
A wheel bearing device 1 shown in FIG. 1 is one embodiment of a wheel bearing device according to the present invention, and includes a wheel bearing 10 and a constant velocity universal joint 20 .

In the following description, the axial direction refers to the direction along the rotation axis X of the wheel bearing 10. The outer side refers to one side in the axial direction, which is the wheel side of the wheel bearing device 1 when it is attached to the vehicle body, and the inner side refers to the other side in the axial direction, which is the vehicle body side of the wheel bearing device 1 when it is attached to the vehicle body.

(Wheel bearings)
The wheel bearing 10 rotatably supports a wheel in a suspension system of a vehicle such as an automobile. The wheel bearing 10 includes an outer ring 2 as an outer member, a hub wheel 3 and an inner ring 4 as inner members, two rolling rows consisting of an inner ball row 5 and an outer ball row 6, an inner seal member 9A, and an outer seal member 9B.

An inner side opening 2a is formed at the inner side end of the outer ring 2 into which the inner side seal member 9A can be fitted. An outer side opening 2b is formed at the outer side end of the outer ring 2 into which the outer side seal member 9B can be fitted.

The inner side seal member 9A fits into the inner side opening 2a, blocking the inner side opening end of the annular space 15 formed by the outer ring 2 and the inner member. The outer side seal member 9B fits into the outer side opening 2b, blocking the outer side opening end of the annular space 15.

The inner peripheral surface of the outer ring 2 is formed with an inner outer raceway surface 2c and an outer outer raceway surface 2d. The outer peripheral surface 2o of the outer ring 2 is integrally formed with a vehicle body mounting flange 2e for mounting the outer ring 2 to a vehicle body member (knuckle).

The inner end of the outer circumferential surface 3o of the hub wheel 3 is formed with a small diameter step 3a that is smaller in diameter than the outer end and extends in the axial direction. A shoulder 3i is formed at the outer end of the small diameter step 3a of the hub wheel 3.

A wheel mounting flange 3b for mounting a wheel is integrally formed on the outer end of the hub wheel 3. The wheel mounting flange 3b has bolt holes 3f into which hub bolts are press-fitted or into which wheel bolts are screwed. The wheel mounting flange 3b has a flange surface 3j against which the brake rotor assembled to the wheel mounting flange 3b abuts.

The hub wheel 3 is formed with an outer inner raceway surface 3c that faces the outer outer raceway surface 2d on the outer side of the outer ring 2. The hub wheel 3 also has a lip sliding surface 3d formed on the base side of the wheel mounting flange 3b, against which the outer seal member 9B slides.

A through hole 3e is formed along the axial direction in the inner diameter portion of the hub wheel 3, to which the constant velocity universal joint 20 is connected. The through hole 3e passes through the hub wheel 3 in the axial direction. The inner ring 4 is fitted into the small diameter step portion 3a of the hub wheel 3.

The inner raceway 4a is formed on the outer peripheral surface of the inner ring 4. In other words, the inner raceway 4a is formed by the inner ring 4 on the inner side of the hub ring 3. The inner raceway 4a faces the outer raceway 2c on the inner side of the outer ring 2.

The inner ring 4 has an inner end face 4b at its inner end and an outer end face 4c at its outer end. The outer end face 4c located at the outer end of the inner ring 4 abuts against the shoulder 3i of the hub wheel 3 from the inner side. The outer end face 4c is an example of a first abutment surface. The inner ring 4 is formed in a tapered shape that expands in diameter from the outer side to the inner side, and the inner end face 4b is located on the outer diameter side of the outer end face 4c in the radial direction.

The inner ball row 5 and outer ball row 6, which are rolling rows, are formed by a plurality of balls 7, which are rolling elements, held by a cage 8. The inner ball row 5 is rollably sandwiched between the inner raceway surface 4a of the inner ring 4 and the outer raceway surface 2c on the inner side of the outer ring 2. The outer ball row 6 is rollably sandwiched between the inner raceway surface 3c of the hub ring 3 and the outer raceway surface 2d on the outer side of the outer ring 2. The inner ring 4 applies a preload to the inner ball row 5 and outer ball row 6, which are rolling rows.

In the wheel bearing 10, a double-row angular ball bearing is formed by the outer ring 2, the hub ring 3, the inner ring 4, the inner ball row 5, and the outer ball row 6. The wheel bearing 10 may also be formed by a double-row tapered roller bearing.

(Constant velocity universal joint)
The constant velocity universal joint 20 includes an outer joint member 21 having track grooves 25 formed on its inner circumferential surface, an inner joint member 22 having track grooves 22 a formed on its outer circumferential surface opposing the track groove 25, balls 23 assembled between the track groove 25 and the track groove 22 a, and a cage 24 interposed between the inner circumferential surface of the outer joint member 21 and the outer circumferential surface of the inner joint member 22 to hold the balls 23.

The outer joint member 21 has a mouth portion 26 that houses the internal parts consisting of the inner joint member 22, the ball 23, and the cage 24, and a stem portion 27 that extends integrally from the mouth portion 26 toward the outer side in the axial direction. The stem portion 27 is fitted into the through hole 3e of the hub wheel 3. The stem portion 27 is an example of a fitting portion that can be fitted into the through hole of the hub wheel.

The shaft end of the shaft 31, to which the driving force from a driving source such as an engine or a motor is input, is press-fitted into the inner joint member 22. The inner joint member 22 and the shaft 31 are connected by a spline fit so that torque can be transmitted. The mouth portion 26 of the outer joint member 21 supports the shaft 31 rotatably about the rotation axis X via the inner joint member 22, the ball 23, and the cage 24. The shaft 31 can rotate around the rotation center P of the mouse portion 26.

[Fitting structure between hub wheel and stem portion]
2 to 4, a recess 3h extending along the axial direction is formed on the inner circumferential surface of the through hole 3e in the hub wheel 3. A plurality of recesses 3h are formed along the circumferential direction. The axial length of the recess 3h is L1.

The outer peripheral surface of the stem portion 27 of the constant velocity universal joint 20 is formed with a protrusion 28 that extends along the axial direction and can be spline-fitted into the recess 3h. Multiple protrusions 28 are formed along the circumferential direction.

The female spline is made up of multiple recesses 3h formed along the circumferential direction, and the male spline is made up of multiple protrusions 28 formed along the circumferential direction.

The protrusion 28 has a first protrusion 28A and a second protrusion 28B located on the outer side of the first protrusion 28A. The first protrusion 28A and the second protrusion 28B are formed so as to be located in the same phase in the circumferential direction.

The first protrusion 28A is formed with a larger diameter than the recess 3h and has a tightening margin n with respect to the recess 3h. The first protrusion 28A is press-fitted into the recess 3h, so that it can be fitted in a state of total close contact with the recess 3h.

The second protrusion 28B is formed with a smaller diameter than the recess 3h, and is configured to be spline-fitted with a gap m between it and the recess 3h. The second protrusion 28B is mainly a protrusion that is guided by the recess 3h when spline-fitting the protrusion 28 and the recess 3h, and is used to align the phase of the recess 3h and the first protrusion 28A in the circumferential direction.

The first convex portion 28A and the second convex portion 28B are spaced apart in the axial direction, and a groove portion 29 is formed between the first convex portion 28A and the second convex portion 28B, which is recessed toward the inner diameter side of the first convex portion 28A and the second convex portion 28B. The axial length of the groove portion 29 is L2. The axial length L2, which is the size of the axial distance between the first convex portion 28A and the second convex portion 28B, is smaller than the axial length L1 of the recess 3h.

The first convex portion 28A and the second convex portion 28B can be formed, for example, by performing a rolling process on the outer peripheral surface of the stem portion 27. In addition, the groove portion 29 can be formed by performing machining such as cutting toward the inner diameter side on the portion between the first convex portion 28A and the second convex portion 28B after the first convex portion 28A and the second convex portion 28B are formed.

By forming the groove 29 between the first protrusion 28A and the second protrusion 28B by machining, the outer end surface of the first protrusion 28A facing the groove 29 can be easily formed into a surface perpendicular to the axial direction.

The portion of the stem portion 27 where the first protrusion 28A is formed is preferably a hardened portion that has been subjected to a heat-hardening treatment. In addition to the portion of the stem portion 27 where the first protrusion 28A is formed, the portion of the stem portion 27 where the second protrusion 28B is formed can also be formed as a hardened portion that has been subjected to a heat-hardening treatment. As the heat-hardening treatment applied to the first protrusion 28A and the second protrusion 28B, various heat treatments such as induction hardening and carburizing hardening can be used.

On the other hand, the recess 3h is formed in a portion of the hub wheel 3 that is non-treated material (raw material) that has not been subjected to a heat hardening treatment. In other words, the portion of the hub wheel 3 where the recess 3h is formed can be formed as a non-treated portion that has not been subjected to a heat hardening treatment.

The stem portion 27 has a male threaded portion 27a at the outer end, and a nut 30 is screwed onto the male threaded portion 27a, so that the hub wheel 3 and the constant velocity universal joint 20 are fastened together with the stem portion 27 fitted into the through hole 3e (see FIG. 1). This fixes the wheel bearing 10 and the constant velocity universal joint 20 together.

In the wheel bearing device 1, when fitting the stem portion 27 of the constant velocity universal joint 20 to the hub wheel 3, the stem portion 27 is inserted into the through hole 3e of the hub wheel 3 from the inner side, and then the nut 30 is screwed onto the male threaded portion 27a to pull the stem portion 27 to the outer side of the through hole 3e, thereby making it possible to fit the convex portion 28 of the stem portion 27 to the concave portion 3h of the hub wheel 3.

In this case, when the stem portion 27 is inserted into the through hole 3e of the hub wheel 3 from the inner side, as shown in FIG. 3, the second protrusion 28B of the stem portion 27 is first spline-fitted into the recess 3h of the hub wheel 3. The second protrusion 28B is formed with a smaller diameter than the recess 3h, and a gap m is formed between the second protrusion 28B and the recess 3h in the circumferential and radial directions.

As a result, when the protrusion 28 of the stem portion 27 is fitted into the recess 3h of the hub wheel 3, the second protrusion 28B is guided by the recess 3h, allowing the circumferential phase of the protrusion 28 and the recess 3h to be determined. Therefore, the protrusion 28 can be easily and reliably fitted into the recess 3h, improving the ease of assembly of the constant velocity universal joint 20 to the hub wheel 3.

In this embodiment, the second protrusion 28B is spline-fitted to the recess 3h with a gap m in both the circumferential and radial directions, but the second protrusion 28B can also be formed to spline-fit to the recess 3h with a gap m only in the circumferential direction or a gap m only in the radial direction.

When the stem portion 27 is further inserted from the state shown in Figure 3 toward the outer side of the through hole 3e, the first convex portion 28A fits into the concave portion 3h as shown in Figure 4. In this case, the first convex portion 28A is formed with a larger diameter than the concave portion 3h, and the concave portion 3h has a tightening margin n for the first convex portion 28A, so the first convex portion 28A is pressed into the concave portion 3h.

When the first protrusion 28A is pressed into the recess 3h, the shape of the first protrusion 28A is transferred to the inner circumferential surface of the recess 3h. In this case, the inner circumferential surface of the recess 3h is very slightly cut by the first protrusion 28A, and the shape of the first protrusion 28A is transferred to the inner circumferential surface of the recess 3h with very slight plastic deformation and elastic deformation.

When the first protrusion 28A is pressed into the recess 3h and the inner peripheral surface of the recess 3h is cut by the first protrusion 28A, cutting chips 3k are generated by cutting the recess 3h, but the generated cutting chips 3k can be held in the groove 29 between the first protrusion 28A and the second protrusion 28B. This makes it possible to prevent the cutting chips 3k from scattering to various parts of the wheel bearing device 1.

When the first protrusion 28A is pressed into the recess 3h, the first protrusion 28A can be pressed into the recess 3h, for example, by pressing the constant velocity universal joint 20 toward the outer side in the axial direction relative to the hub wheel 3.

When the first protrusion 28A is press-fitted into the recess 3h and the first protrusion 28A and the recess 3h are spline-fitted, the outer peripheral surface of the first protrusion 28A and the inner peripheral surface of the recess 3h are in full contact with each other.

In this way, the first protrusion 28A and the recess 3h are spline-fitted with a tightening margin n, and the spline-fitted first protrusion 28A and recess 3h are in close contact with each other in the axial direction.

By spline-fitting the first convex portion 28A and the concave portion 3h in a state of total contact, it is possible to reduce misalignment that occurs between the wheel bearing 10 and the constant velocity universal joint 20 that are fitted together.

In addition, by spline-fitting the first protrusion 28A and the recess 3h in a state of total contact, the allowable torque of the spline-fitted portion can be increased, and the axial length of the portion where the first protrusion 28A and the recess 3h are spline-fitted can be shortened, making it possible to reduce the weight of the wheel bearing 10.

[Inner ring and mouth part]
As shown in Fig. 5, the inner ring 4 has an inner ring fitting portion 4A, a large end portion 4B, and a tapered portion 4C. The inner ring fitting portion 4A is a portion that fits into the small diameter step portion 3a of the hub wheel 3, and has an inner circumferential surface 41 that serves as a fitting surface for the small diameter step portion 3a. The inner diameter of the inner circumferential surface 41 is R1. The inner circumferential surface 41 is an example of a first inner circumferential surface. The outer side end face 4c of the inner ring 4 is located at the outer side end portion of the inner ring fitting portion 4A.

The inner ring 4 is located at the inner end of the inner ring fitting portion 4A, and has an inner ring abutment surface 4d against which the mouth portion 26 of the constant velocity universal joint 20 abuts. The inner ring abutment surface 4d is an example of a second abutment surface. The inner ring abutment surface 4d is a surface perpendicular to the axial direction, and faces the inner side in the axial direction. The area of the inner ring abutment surface 4d is formed to be larger than the area of the outer end face 4c.

The big end 4B is located axially inward of the inner ring fitting portion 4A and has an inner peripheral surface 42 that is larger in diameter than the inner peripheral surface 41 of the inner ring fitting portion 4A. The inner diameter R2 of the inner peripheral surface 42 is larger than the inner diameter R1 of the inner peripheral surface 41.

The inner peripheral surface 42 is a surface parallel to the axial direction. The inner peripheral surface 42 is an example of a second inner peripheral surface. The inner end surface 4b of the inner ring 4 is located at the inner end of the big end 4B. The inner ring abutment surface 4d is located radially inward of the inner peripheral surface 42 of the big end 4B, and is located axially outward of the big end 4B.

The tapered portion 4C is the portion that connects the inner ring fitting portion 4A and the big end portion 4B, and is formed in a tapered shape that expands in diameter from the outer side to the inner side.

The mouth portion 26 of the outer joint member 21 has a joint-side abutment surface 26a. The joint-side abutment surface 26a is a surface perpendicular to the axial direction and is located at the outer end of the mouth portion 26. The joint-side abutment surface 26a faces the inner ring-side abutment surface 4d of the inner ring 4 in the axial direction and abuts against the inner ring-side abutment surface 4d.

When the nut 30 is screwed onto the male threaded portion 27a and the stem portion 27 is fitted into the through hole 3e, the joint side abutment surface 26a of the mouth portion 26 abuts against the inner ring side abutment surface 4d of the inner ring 4, and the inner ring 4 is pressed axially toward the outer side by the mouth portion 26. By pressing the inner ring 4 toward the outer side, a preload can be applied to the inner ball row 5 and the outer ball row 6 inside the wheel bearing 10.

In this case, the inner ring abutment surface 4d is a surface perpendicular to the axial direction, and the area of the inner ring abutment surface 4d is formed larger than the area of the outer end face 4c. Therefore, when the inner ring abutment surface 4d is pressed by the mouth portion 26, the pressing force from the mouth portion 26 to the inner ring 4 can be reliably applied in the axial direction, and sufficient preload can be applied to the inside of the wheel bearing 10. This makes it possible to suppress creep of the inner ring 4 against the hub wheel 3, and to suppress fretting wear on the mating surface between the inner ring 4 and the hub wheel 3.

As shown in FIG. 6, the mouth portion 26 is located on the inner side of the joint-side abutment surface 26a and has an opposing surface 26b that is a surface parallel to the axial direction. The opposing surface 26b faces the inner peripheral surface 42 of the big end 4B in the radial direction with a gap D1. In this embodiment, the gap D1 is set to 0.1 mm or less.

The inner ring 4 of the wheel bearing 10 has a shape that expands in diameter from the inner ring fitting portion 4A to the big end 4B, so when a turning moment is applied, the inner ring 4 may deform, which may affect the life of the inner raceway surface 4a.

However, in the wheel bearing device 1, the gap D1 between the inner circumferential surface 42 of the big end 4B and the opposing surface 26b of the mouth portion 26 is set to a small value of 0.1 mm or less, so that when a turning moment is applied to the inner ring 4, the inner circumferential surface 42 of the big end 4B comes into contact with the opposing surface 26b of the mouth portion 26, making it possible to suppress deformation of the inner ring 4.

In addition, in the wheel bearing device 1, the wheel bearing 10 and the constant velocity universal joint 20 are configured to be spline-fitted with a small misalignment, with the first convex portion 28A of the stem portion 27 and the concave portion 3h of the hub wheel 3 in full contact with each other. Therefore, even if the gap D1 between the inner peripheral surface 42 of the big end 4B and the opposing surface 26b of the mouth portion 26 is small, interference between the stem portion 27 and the hub wheel 3 can be suppressed when inserting the stem portion 27 of the constant velocity universal joint 20 into the through hole 3e of the hub wheel 3, improving the workability when fitting the constant velocity universal joint 20 to the wheel bearing 10.

At the inner end of the inner circumferential surface 42 of the large end 4B, a groove 42a is formed that is recessed from the inner circumferential surface 42 toward the outer diameter side. At the inner end of the opposing surface 26b of the mouth portion 26, a groove 26c is formed that is recessed from the opposing surface 26b toward the inner diameter side.

A seal member 50 such as an O-ring is fitted into the groove 42a of the big end 4B and the groove 26c of the mouth portion 26. In other words, the seal member 50 is interposed between the inner circumferential surface 42 of the big end 4B and the opposing surface 26b of the mouth portion 26, and the seal member 50 seals the gap D1 between the inner circumferential surface 42 and the opposing surface 26b. In this way, by sealing the gap D1 between the inner circumferential surface 42 and the opposing surface 26b with the seal member 50, it is possible to prevent foreign matter such as water from entering between the inner ring 4 and the mouth portion 26.

[Inner ball row and outer ball row]
5, the ball 7 in the inner ball row 5 is in contact with the inner raceway surface 4a of the inner ring 4 at a contact position 43, and the contact angle of the ball 7 in the inner ball row 5 with respect to the inner raceway surface 4a is θ1. The contact angle θ1 is the inclination angle of the straight line connecting the center C of the ball 7 in the inner ball row 5 and the contact position 43 with respect to the radial direction.

The ball 7 in the outer ball row 6 is in contact with the inner raceway surface 3c of the hub wheel 3 at the contact position 3m, and the contact angle of the ball 7 in the outer ball row 6 with respect to the inner raceway surface 3c is θ2. The contact angle θ2 is the inclination angle with respect to the radial direction of the straight line connecting the center C of the ball 7 in the outer ball row 6 and the contact position 3m.

The contact position 43 on the inner raceway surface 4a of the inner ring 4 is located a length D2 away from the groove bottom 25a of the track groove 25 formed in the mouth portion 26. This allows the inner diameter R2 of the inner peripheral surface 42 of the big end 4B of the inner ring 4 to be made large, and the rotation center P of the mouse portion 26 and the flange surface 3j of the wheel mounting flange 3b of the hub wheel 3 can be positioned closer to each other in the axial direction, making it possible to narrow the width of the wheel bearing device 1.

In addition, by reducing the distance between the flange surface 3j of the wheel mounting flange 3b to which the wheel is attached and the rotation center P of the mouse part 26, the rotation center P of the mouse part 26 can be brought closer to the wheel side. This makes it possible to reduce the maximum angle between the rotation axis X of the wheel bearing device 1 and the axis of the shaft 31 in the constant velocity universal joint 20 during steering.

In addition, the contact position 3m between the inner raceway surface 3c of the hub ring 3 and the balls 7 of the outer ball row 6 is located on the inner diameter side of the contact position 43 between the inner raceway surface 4a of the inner ring 4 and the balls 7 of the inner ball row 5.

In this way, by positioning the contact position 3m on the inner raceway surface 3c of the hub wheel 3 on the inner diameter side of the contact position 43 on the inner raceway surface 4a of the inner ring 4, the outer ball row 6 and the inner ball row 5 can be positioned closer together in the axial direction, making it possible to narrow the wheel bearing 10 in the axial direction.

The retainer 8 has a first retainer 8A for the outer ball row 6 and a second retainer 8B for the inner ball row 5. The first retainer 8A and the second retainer 8B each have an annular ring portion 81, a plurality of column portions 82 extending axially from the annular ring portion 81 and arranged at regular intervals along the circumferential direction, and a pocket 83 formed by the column portions 82 adjacent to the annular ring portion 81 and holding the balls 7. The annular ring portion 81 protrudes axially further than the balls 7.

In the first retainer 8A of the outer ball row 6, the annular portion 81 is located on the outer side of the ball 7, and in the second retainer 8B of the inner ball row 5, the annular portion 81 is located on the inner side of the ball 7.

In other words, in the axial direction, the annular portion 81 of the first retainer 8A of the outer ball row 6 protrudes on the side opposite the inner ball row 5, and the annular portion 81 of the second retainer 8B of the inner ball row 5 protrudes on the side opposite the outer ball row 6, and the annular portion 81 is not located between the outer ball row 6 and the inner ball row 5.

Therefore, even if the contact position 3m with the ball 7 on the inner raceway surface 3c of the hub ring 3 is located on the inner diameter side of the contact position 43 with the ball 7 on the inner raceway surface 4a of the inner ring 4, the annular portion 81 of the retainer 8 can be prevented from interfering with the outer raceway surfaces 2c, 2d. Furthermore, even if the outer ball row 6 and the inner ball row 5 are arranged close to each other in the axial direction, the annular portion 81 of the retainer 8 does not interfere with the outer ball row 6 and the inner ball row 5, making it possible to further narrow the wheel bearing 10 in the axial direction.

Although the embodiments of the present invention have been described above, the present invention is in no way limited to these embodiments, which are merely examples, and it goes without saying that the present invention can be embodied in various other forms without departing from the spirit of the present invention. The scope of the present invention is indicated by the claims, and further includes the equivalent meanings set forth in the claims, and all modifications within the scope of the claims.

LIST OF SYMBOLS 1 Wheel bearing device 2 Outer ring 2c (inner side) outer raceway surface 2d (outer side) outer raceway surface 3 Hub ring 3a Small diameter step portion 3b Wheel mounting flange 3c Inner raceway surface 3e Through hole 3h Recess 3j Flange surface 3m Contact position (on inner raceway surface of hub ring) 4 Inner ring 4a Inner raceway surface 4c Outer side end face 4d Inner ring abutment surface 4A Inner ring fitting surface 4B Big end 4C Tapered portion 5 Inner side ball row 6 Outer side ball row 7 Ball 8 Cage 8A First cage 8B Second cage 10 Wheel bearing 20 Constant velocity universal joint 25 Track groove 25a Groove bottom 26 Mouth portion 26a Joint side abutment surface 26b Opposing surface 27 Stem portion 28 Convex portion 28A First protrusion 28B Second protrusion 31 Shaft 41 Inner peripheral surface (of inner ring fitting portion) 42 Inner peripheral surface (of big end) 43 Contact position (on inner raceway surface of inner ring) 50 Seal member 81 Annular portion 82 Pillar portion 83 Pocket

Claims (6)

a wheel bearing comprising an outer member having a double row outer raceway surface on its inner circumference, a hub ring having a wheel mounting flange for mounting a wheel at one axial end thereof, a small diameter step portion extending axially on its outer circumference, and a through hole penetrating axially in its inner diameter portion, and at least one inner ring fitted into the small diameter step portion of the hub ring, an inner member having a double row inner raceway surface facing the double row outer raceway surface, and double row rolling elements accommodated in a rollable manner between both the raceway surfaces of the outer member and the inner member;
a constant velocity universal joint having a mouth portion having a track groove formed on an inner peripheral surface thereof, and a fitting portion extending in an axial direction from the mouth portion and capable of being fitted into the through hole of the hub wheel from the other axial side;
A wheel bearing device comprising:
a contact position between the inner raceway surface on the other axial side of the inner member and the rolling elements is located on the outer diameter side of a groove bottom of the track groove in the mouth portion,
The inner ring is
an inner ring fitting portion that is fitted into the small diameter step portion of the hub wheel;
a first contact surface that is located at one axial end of the inner ring fitting portion and that contacts the hub wheel from the other axial side;
a big end portion located on the other axial side of the inner ring fitting portion and having a second inner circumferential surface having a larger diameter than the first inner circumferential surface of the inner ring fitting portion;
a second abutment surface that is located radially inward relative to the second inner circumferential surface of the big end and against which the mouth portion abuts from the other side in the axial direction,
The second abutment surface is a surface perpendicular to the axial direction,
A wheel bearing device according to claim 1, wherein an area of the second contact surface is larger than an area of the first contact surface. The wheel bearing device according to claim 1, wherein the contact position between the inner raceway surface on one axial side of the inner member and the rolling elements is located on the inner diameter side of the contact position between the inner raceway surface on the other axial side of the inner member and the rolling elements. a first cage that holds the rolling elements housed between the raceway surfaces on one side in the axial direction, and a second cage that holds the rolling elements housed between the raceway surfaces on the other side in the axial direction,
each of the first cage and the second cage has an annular portion formed in an annular shape, and a plurality of pillar portions extending in the axial direction from the annular portion and forming pockets for holding the rolling elements;
the annular portion of the first cage is located on one axial side of the rolling element accommodated between the raceway surfaces on one axial side,
3. The wheel bearing device according to claim 1, wherein the annular portion of the second cage is located on the other axial side of the rolling elements housed between the raceway surfaces on the other axial side. the second inner circumferential surface of the inner ring is a surface parallel to the axial direction,
the mouth portion has an opposing surface that is parallel to the axial direction and faces the second inner circumferential surface with a gap therebetween in a radial direction,
2. The wheel bearing device according to claim 1, wherein a gap between the second inner circumferential surface and the opposing surface is 0.1 mm or less. The wheel bearing device according to claim 4, wherein a seal member that seals the gap is interposed between the second inner circumferential surface and the opposing surface. a recessed portion extending in an axial direction is formed on an inner peripheral surface of the through hole in the hub wheel,
6. A wheel bearing device as claimed in claim 4 or claim 5, wherein a convex portion is formed on an outer peripheral surface of the mating portion of the constant velocity universal joint, the convex portion extending along the axial direction and spline-fitting into the concave portion in a state of total contact.

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