JP2008121813A - Bearing device for wheel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bearing device for a wheel enabling relaxing of generated stress and securing sealing performance at a base part of a hub flange. <P>SOLUTION: The bearing device for the wheel is provided with seal means 11, 12 for sealing an outboard side end and an inboard side end of a bearing space between an outer member 1 and an inner member 2. The inner member 2 comprises a hub wheel 13 and an inner ring 14. The seal means 11 of the outboard side end comprises a contact seal 18 mounted to the outer member 1 and a labyrinth seal clearance 28. An outer surface portion continued from the outboard side end of a shaft part 13a of the hub wheel 13 to a side surface of the hub flange 15 comprises a shaft part end surface 21 becoming a large diameter as it reaches to the outboard side; a corner part circular surface 22 of a circular cross section continued to the shaft part end surface 21; and a base circular surface 23 of a circular cross section continued from the corner part circular surface 22 to the side surface of the hub flange 15. An inner peripheral surface and an end surface at the outboard side of the outer member 1 approach to the corner part circular surface 22 to form a clearance of an L shaped cross section becoming the labyrinth seal clearance 28 between the corner part circular surface 22 and the outer member 1. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a wheel bearing device in an automobile or the like, and more particularly to a seal structure on the outboard side.

Bearing devices used in vehicles such as automobiles are in a harsh environment where they are exposed to road surfaces, etc., so it is necessary to prevent dust and muddy water from entering the system from the outside. A high effect is also required for prevention of the above.
For this reason, for example, a seal structure as shown in FIG. 6 is employed (for example, Patent Document 1). The bearing device shown in FIG. 1 has an annular space formed between inner and outer members 32, 31 in which balls 33 are interposed between double-row raceway surfaces 34, 35 of an outer member 31 and an inner member 32. The end portions on the outboard side and the inboard side are sealed with sealing means 37 and 38, respectively. The inward member 32 includes a hub wheel 43 having a hub flange 45 for attaching a wheel, and an inner ring 44 fitted to the outer periphery of the inboard side end of the shaft portion 43a of the hub wheel 43.

  As shown in an enlarged view in FIG. 7, the sealing structure of the sealing means 37 on the outboard side includes a contact seal 48 attached to the outer member 31 and slidably contacting the shaft end surface 51 of the hub wheel 43, and the contact seal 48. And a labyrinth seal gap 58 formed between the hub wheel 43 and the end face of the outer member 31 on the outboard side.

There are several types of cross-sectional shapes of the labyrinth seal gap 58 in this case, but in this example, the labyrinth seal gap 58 is a cross-section in which the diameter of the labyrinth seal gap 58 changes in a single direction from the shaft end surface 51 to the root arc surface 53. It shall be arcuate.
In addition, as shown in FIG. 8, there is a labyrinth seal gap 58 having an L-shaped cross-sectional shape.
JP 2005-147298 A

As the shape of the labyrinth seal gap 58, the L-shaped cross-sectional shape as shown in FIG. However, in the case of this shape, when a moment load is applied, stress concentrates on the corner portion 43c between the cylindrical surface portion 43a forming the labyrinth seal gap 58 of the hub wheel 43 and the hub flange side surface 43b, and the hub wheel 43 is damaged. May lead to
As shown in FIG. 7, when the labyrinth seal gap 58 is formed in a cross-sectional arc shape in which the diameter of the labyrinth seal gap changes from the shaft end surface 51 toward the root arc surface 53, the problem of stress concentration is reduced. However, such a cross-sectional shape reduces the sealing performance, so this design is not optimal.

  An object of the present invention is to provide a wheel bearing device capable of relaxing generated stress and ensuring sealing performance at the base portion of a hub flange.

The wheel bearing device of the present invention includes an outer member having a double-row raceway surface on the inner periphery and attached to the vehicle body, and a double-row raceway surface facing the raceway surface on the outer periphery. An inner member having a hub flange for wheel attachment on the outer periphery, a double row rolling element interposed between the raceway surfaces of the outer member and the inner member, and a bearing space between the outer member and the inner member. Sealing means for sealing each of the outboard side end and the inboard side end, and the inner member is fitted to the outer periphery of the hub ring having the hub flange and the inboard side end of the shaft portion of the hub ring. It is applied to a wheel bearing device composed of an inner ring.
In this wheel bearing device, the outboard side end sealing means includes a contact seal attached to the outer member and having a tip contacting the hub wheel, and the outer side outside the bearing space than the contact seal. A labyrinth seal gap formed between the side member and the hub wheel, and the outer surface portion that continues from the outboard side end of the shaft portion of the hub wheel to the side surface of the hub flange increases in diameter toward the outboard side. An end surface of the shaft, a corner arc surface having a cross-sectional arc shape following the end surface of the shaft portion, and a base arc surface having a cross-section arc shape continuing from the corner arc surface to the side surface of the hub flange. An inner peripheral surface and an end surface on the outboard side are close to the corner arc surface, and a gap having an L-shaped cross section serving as the labyrinth seal gap is formed between the corner arc surface and the outer member.

According to this configuration, the outer surface portion of the hub wheel shaft portion that extends from the outboard side end to the side surface of the hub flange increases in diameter toward the outboard side, and the cross-sectional arc shape continues to the shaft end surface. And an inner peripheral surface and an end surface on the outboard side of the outer member are the corner circular arc surface. Since the labyrinth seal gap has an L-shaped cross section, the labyrinth seal gap is formed between the corner arc surface and the outer member, and the labyrinth seal gap has an L-shaped cross section. Sealing performance can be obtained. That is, when the cross section is L-shaped, a bending point is formed, so that the muddy water to be infiltrated has an action such that the flow is stopped once at the bending point. Therefore, it is considered that muddy water does not easily enter the sealed portion of the outboard contact seal.
In addition, the hub wheel has a shaft end face whose outer surface portion extending from the end of the shaft portion to the side of the hub flange increases in diameter toward the outboard side, and a cross-sectional arc-shaped corner following the shaft end surface. And a root arc surface with a circular arc section that continues from the corner arc surface to the side surface of the hub flange, so that when a moment load is applied to the wheel bearing device, the stress at the root portion of the hub flange is reduced. Concentration is relaxed, and the strength and durability are excellent.

In this invention, the pitch circle diameter of the rolling element row on the outboard side is larger than the pitch circle diameter of the rolling element row on the inboard side, and the number of rolling elements in the rolling body row on the outboard side is It may be larger than the number of rolling elements in the rolling element row.
With wheel bearings, a large load acts on the outboard side when traveling on curved roads. In this configuration, since the pitch circle diameter of the rolling body row on the outboard side is increased and the number of rolling bodies on the outboard side is increased, the bearing rigidity and load capacity on the outboard side are increased. Therefore, it is possible to make an optimal design that balances all of the sealing performance, weight, strength, and rigidity.

  According to the wheel bearing device of the present invention, the sealing means on the outboard side end between the outer member and the inner member is constituted by a contact seal and a labyrinth seal gap, and the hub flange is connected to the hub flange from the outboard side end of the shaft portion of the hub wheel. The outer surface part that continues to the side surface of the shaft part end surface that becomes larger in diameter toward the outboard side, the cross-section arc-shaped corner arc surface that follows the end surface of the shaft part, and from this corner arc surface to the side of the hub flange A cross-sectional arc-shaped base arc surface, and the inner peripheral surface and the end surface of the outer member on the outboard side are close to the corner arc surface and between the corner arc surface and the outer member. Since a gap having an L-shaped cross-section serving as a labyrinth seal gap is formed, the stress generated at the root portion of the hub flange is relieved and the sealing performance at the outboard side end is ensured.

  A first embodiment of the present invention will be described with reference to FIGS. This embodiment is a third generation inner ring rotating type and is applied to a wheel bearing device for supporting a driven wheel. In this specification, the side closer to the outer side in the vehicle width direction of the vehicle when attached to the vehicle is referred to as the outboard side, and the side closer to the center of the vehicle is referred to as the inboard side.

  The wheel bearing device includes an outer member 1 having double-row raceway surfaces 3 and 4 formed on the inner periphery, and an inner member having raceway surfaces 5 and 6 facing the raceway surfaces 3 and 4 on the outer periphery. 2 and double-row rolling elements 7 and 8 interposed between the raceway rings 3 and 5 and the raceway surfaces 4 and 6 facing the outer member 1 and the inner member 2. This wheel bearing device is a double-row angular ball bearing, and the rolling elements 7 and 8 are made of balls and are held by cages 9 and 10 for each row. Each of the track surfaces 3 to 6 has an arc shape in cross section, and the track surfaces 3 to 6 are formed so that the contact angles are aligned with the back surface. The outboard side end and the inboard side end of the bearing space between the outer member 1 and the inner member 2 are sealed by sealing means 11 and 12, respectively.

The outer member 1 is a member on the fixed side and is an integral member having a vehicle body mounting flange 1a. A bolt 25 is attached to a knuckle (not shown) on the vehicle body side via the vehicle body mounting flange 1a. It is concluded.
The inner member 2 is a member on the rotation side, and is composed of a hub wheel 13 and an inner ring 14, an outboard side raceway surface 5 on the hub wheel 13, and an inboard side raceway surface 6 on the inner ring 14. Are formed respectively. The hub wheel 13 has a wheel mounting hub flange 15 on the outer periphery of the outboard side end of the shaft portion 13a, and an inner ring fitting surface having a small step-like shape on the outer periphery of the inboard side end of the shaft portion 13a. 16. The inner ring 14 is fitted to the inner ring fitting surface 16 of the hub ring 13 and is fixed to the hub ring 13 by a caulking portion 17 of the hub ring 13. The caulking portion 17 is formed by caulking a cylindrical portion extended to the inboard side end of the hub wheel 13 to the outer diameter side by rolling caulking or the like.

  FIG. 2 shows an enlarged view of part A in FIG. As shown in the figure, the sealing means 11 at the end of the outboard side is attached to the outer member 1 and has a contact seal 18 whose tip contacts the hub wheel 13 and is outside the bearing space than the contact seal 18. The labyrinth seal gap 28 formed between the outer member 1 and the hub wheel 13.

  The contact seal 18 includes a cored bar 19 having an L-shaped cross-section formed by a circumferential part 19 a and a standing plate part 19 b, and an elastic member 20 fixed to the cored bar 19. The contact seal 18 is attached to the outer member 1 by fitting the circumferential portion 19 a of the core metal 19 to the inner diameter surface of the outer member 1.

  The outer surface portion of the shaft portion 13a of the hub wheel 13 that extends from the end of the outboard side to the side surface of the hub flange 15 has a shaft end surface 21 having an arc cross section that increases in diameter toward the outboard side, and the shaft end surface 21. A corner arc surface 22 having an arcuate cross section and a root arc surface 23 having an arc cross section following the planar side surface of the hub flange 15 from the corner arc surface 22.

  The elastic member 20 of the contact seal 18 is formed with three seal lips 20 a, 20 b, 20 c with the shaft end face 21 of the hub wheel 13 as a seal face and the tip end facing the shaft end face 21. Among them, each of the seal lips 20b and 20c except for the innermost seal lip 20a with respect to the bearing space between the outer member 1 and the hub wheel 13 is a dust lip that prevents intrusion of dust and muddy water, and each tip has a bearing space. It is formed to extend outward. These dust strips 20b and 20c are in contact with the shaft end face 21 with a tightening margin. The innermost seal lip 20a is a grease lip that prevents the enclosed grease from flowing out. The tip of the seal lip 20a is formed so as to extend inside the bearing space, and is in contact with the bearing end surface 21 with a tightening margin. .

  The labyrinth seal gap 28 has an inner peripheral surface and an end surface on the outboard side of the outer member 1 close to the corner arc surface 22 of the hub wheel 13, and between the corner arc surface 22 and the outer member 1. Is a gap having an L-shaped cross section formed by

A radius difference (R2) between the labyrinth corner arc starting diameter R1 which is the diameter of the minimum diameter portion of the corner arc surface 22 of the hub wheel 13 and the root arc starting diameter R2 which is the diameter of the minimum diameter portion of the root arc surface 23. -R1) is set so that the ratio (R2-R1) / r with respect to the radius of curvature r of the corner arc surface 22 is 0.75 to 1.25, that is, the following equation is satisfied. ing.
0.75 ≦ (R2−R1) /r≦1.25 (1)

According to the wheel bearing device of this configuration, the outer surface portion of the shaft portion 13a of the hub wheel 13 that extends from the end of the outboard side to the side surface of the hub flange 15 has a shaft end surface 21 that increases in diameter toward the outboard side. A corner circular arc surface 22 having a circular arc shape following the shaft end face 21 and a root circular arc surface 23 having a circular arc shape continuing from the corner circular arc surface 22 to the side surface of the hub flange 15 are provided. The inner peripheral surface and the end surface on the side are close to the corner arc surface 22 and an L-shaped gap is formed between the corner arc surface 22 and the outer member 1 to form the labyrinth seal gap 28. Since the labyrinth seal gap 28 has an L-shaped cross section, excellent sealing performance can be obtained. That is, when the cross section is L-shaped, a bending point is formed, so that the muddy water to be infiltrated has an action such that the flow is stopped once at the bending point. Therefore, it is considered that muddy water does not easily enter the sealed portion of the outboard contact seal. Since the muddy water is applied to the upper side of FIG. 2 and then flows downward while being transmitted through the labyrinth seal gap 28, it is considered that the action of stopping the flow occurs if it is L-shaped.
Further, the hub wheel 13 has a shaft portion end surface 21 in which an outer surface portion that continues from the end of the shaft portion 13a to the side surface of the hub flange 15 increases toward the outboard side, and the shaft portion end surface 21 continues. Since a corner arc surface 22 having an arc shape in cross section and a root arc surface 23 having an arc shape in cross section extending from the corner arc surface 22 to the side surface of the hub flange 15, a moment load is applied to the wheel bearing device. The stress concentration at the base of the hub flange 15 is alleviated, and the strength and durability are excellent.

  Further, in this embodiment, the labyrinth corner arc starting diameter R1 that is the diameter of the minimum diameter portion of the corner arc surface 22 in the shaft portion 13a of the hub wheel 13 and the root arc that is the diameter of the minimum diameter portion of the root arc surface 23 are included. The radius difference (R2-R1) with respect to the starting diameter R2 is such that the ratio of the radius of curvature (R2-R1) / r with respect to the radius of curvature r of the corner arcuate surface 22 is within a predetermined range, that is, 0. Since the dimensional relationship is in the range of .75 to 1.25, the sealing performance at the outboard side end is ensured, and the generated stress at the root portion of the hub flange 15 is relieved.

That is, even if the labyrinth seal gap 28 has an L-shaped cross section, if the surface facing the outer member 1 in the radial direction is shortened, the inlet becomes wider and mud becomes easy to enter. R2-R1) / r is preferably 0.75 or more.
When the radius of curvature r of the corner arc surface 22 is increased, the gap between the corner arc surface 22 and the inner diameter surface of the end of the outer member 1 is reduced and may interfere. When the labyrinth corner arc starting diameter R1 is changed to be small, it is considered that the labyrinth seal gap 28 is increased and the sealing performance is lowered.

  The ratio of the above-mentioned curvature radii is that only the labyrinth corner arc starting diameter R1 is increased without changing the root arc starting diameter R2, and the radius difference (R2-R1) between the labyrinth corner arc starting diameter R1 and the root starting diameter R2 is increased. It can be obtained by making it smaller. As a result, the stress acting on the labyrinth corner arc surface 22 can be dispersed in the root arc surface, and stress relaxation can be achieved. That is, by increasing the labyrinth corner arc starting diameter R1, the strength of the portion is improved, so that the strength difference from the root arc surface 23 is reduced, and as a result, the stress concentrated on the labyrinth corner arc surface 22 is reduced. Dispersed in the arc surface 23, the labyrinth corner arc surface 22 relaxes stress, and the root arc surface 23 with sufficient margin increases in stress. Since the root arc starting diameter R2 is not increased, the overall weight increase of the wheel bearing device can be minimized.

  An analysis example by the finite element method will be described with reference to Table 1 and FIG.

Table 1 is an example in which the stress state of the corner arc surface when the base arc start radius R2 and the radius of curvature r of the corner arc surface 22 are constant and the labyrinth corner arc start radius R1 is variously changed is compared.
According to this analysis result, when the value of (R2-R1) / r is 1.7 (example 1) and the generated stress is 1 (reference), the value of (R2-R1) / r is In the analysis examples 2 to 4, which are 1.29, 1.08, and 0.5, the values are reduced to 0.88, 0.75, 0, and 53, respectively, and the value of (R2−R1) / r is decreased. As a result, the ratio of generated stress decreases. From this, it can be said that it is excellent in terms of stress ratio that the ratio of the radius of curvature is 1.25 or less.

  3 and 4 show another embodiment of the present invention. In this embodiment, in the first embodiment described above with reference to FIGS. 1 and 2, the pitch circle diameter PCDo of the rolling body row 3o on the outboard side is larger than the pitch circle diameter PCDi of the rolling body row 3i on the inboard side. The number of rolling elements 7 of the rolling body row 3o on the outboard side is larger than the number of rolling bodies 8 of the rolling body row 3i on the inboard side.

  In the wheel bearing, a large load acts on the outboard side when traveling on a curved road. In this configuration, since the pitch circle diameter of the rolling body row 3o on the outboard side is increased and the number of the rolling elements 7 on the outboard side is increased, the bearing rigidity and load capacity on the outboard side are increased. Therefore, it is possible to make an optimal design that balances all of the sealing performance, weight, strength, and rigidity. Other configurations and effects are the same as those of the first embodiment.

It is sectional drawing of the wheel bearing apparatus concerning 1st Embodiment of this invention. It is an expanded sectional view of the A section in FIG. It is sectional drawing of the wheel bearing apparatus concerning other embodiment of this invention. It is an expanded sectional view of the B section in FIG. It is a graph which shows the relationship between the labyrinth corner R ratio and the generated stress ratio. It is sectional drawing of an example of the conventional wheel bearing apparatus. It is an expanded sectional view of the E section in FIG. It is a partial expanded sectional view of another prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Outer member 2 ... Inner member 3, 4 ... Outer member raceway surface 5, 6 ... Inner member raceway surface 7, 8 ... Rolling element 11, 12 ... Sealing means 13 ... Hub wheel 13a ... Hub wheel shaft Part 14 ... Inner ring 15 ... Hub flange 18 ... Contact seal 21 ... Shaft end face 22 ... Corner arc surface 23 ... Base arc surface 28 ... Labyrinth seal gap r ... Curvature radius R1 of corner arc surface 22 ... Labyrinth corner arc starting diameter R2: Root arc start diameter

The wheel bearing device of the present invention includes an outer member having a double-row raceway surface on the inner periphery and attached to the vehicle body, and a double-row raceway surface facing the raceway surface on the outer periphery. An inner member having a hub flange for wheel attachment on the outer periphery, a double row rolling element interposed between the raceway surfaces of the outer member and the inner member, and a bearing space between the outer member and the inner member. Sealing means for sealing each of the outboard side end and the inboard side end, and the inner member is fitted to the outer periphery of the hub ring having the hub flange and the inboard side end of the shaft portion of the hub ring. It is applied to a wheel bearing device composed of an inner ring.
In this wheel bearing device , a portion of the inner diameter surface of the outer member from the end on the outboard side to the vicinity of the position where the contact seal is fitted is formed in a step having a larger diameter than the contact seal fitting surface. and, sealing means prior Symbol outboard end, a contact seal tip attached to the outer member is in contact with the hub wheel, the outer member and the hub wheel on the outside of the bearing space than the contact seal A labyrinth seal gap formed between the outer end portion of the hub wheel shaft portion extending from the outboard side end to the side surface of the hub flange, and a shaft end surface that increases in diameter toward the outboard side. A corner arc surface having a cross-section arc shape following the end face of the shaft portion, and a root arc surface having a cross-section arc shape continuing from the corner arc surface to the side surface of the hub flange. Peripheral surface and end surface are the corners Close to the arc surface to form a L-shaped cross section clearance serving as the labyrinth seal gap between the outer member and the corner arc surface.

A portion of the inner diameter surface of the outer member 1 from the end on the outboard side to the vicinity of the position where the contact seal 18 is fitted is formed in a step portion 1b having a larger diameter than the contact seal fitting surface.
Outer surface portion that follows the side of the hub flange 15 from the outboard end of the shaft portion 13a of the hub wheel 13, an arcuate cross-section of the shaft end face 21 of the large diameter according to reach the outboard side, the shaft end face 21 A corner arc surface 22 having an arcuate cross section following the arc and a base arc surface 23 having an arc shape in cross section extending from the corner arc surface 22 to the planar side surface of the hub flange 15.

The wheel bearing device of the present invention includes an outer member having a double-row raceway surface on the inner periphery and attached to the vehicle body, and a double-row raceway surface facing the raceway surface on the outer periphery. An inner member having a hub flange for wheel attachment on the outer periphery, a double row rolling element interposed between the raceway surfaces of the outer member and the inner member, and a bearing space between the outer member and the inner member. Sealing means for sealing each of the outboard side end and the inboard side end, and the inner member is fitted to the outer periphery of the hub ring having the hub flange and the inboard side end of the shaft portion of the hub ring. It is applied to a wheel bearing device composed of an inner ring.
Oite the bearing device for a wheel, in the inner surface of the outer member, the portion from the outboard end to the vicinity of a position where the contact seal is fitted, the stepped portion of larger diameter than the contact seal fitting surface The sealing means on the outboard side end is attached to the outer member, and a contact seal whose tip contacts the hub wheel, and the outer member and the hub wheel outside the bearing space than the contact seal. A labyrinth seal gap formed between the outer end portion of the hub wheel shaft portion extending from the outboard side end to the side surface of the hub flange, and a shaft end surface that increases in diameter toward the outboard side. a circular-arc cross section corners arcuate surface following the axial end face, becomes in a root arc surface arcuate cross section following the side surface of the hub flange from the corner arc surface, an axial end face of the hub wheel, cross Arc-shaped and the contact sheet Of a contact sealing surface, the inner circumferential surface and the end face on the outboard side of the outer member of the outer member between the outer member and the corner portion arcuate surface proximate the corner arc surface The step portion and the corner arc surface on the inner diameter surface are opposed to each other in the radial direction, and the radial labyrinth seal gap, the end surface on the outboard side of the outer member, and the corner arc surface are in the axial direction. Oppositely, a gap having an L-shaped cross section formed by an axial labyrinth seal gap is formed.

Claims (2)

An outer member having a double-row raceway surface on the inner periphery and attached to the vehicle body, and a double-row raceway surface facing the raceway surface on the outer periphery and a hub flange for wheel mounting on the outer periphery of the outboard side end An inner member, double row rolling elements interposed between raceways of the outer member and the inner member, an outboard side end and an inboard side end of a bearing space between the outer member and the inner member In the wheel bearing device, the inner member includes a hub ring having the hub flange and an inner ring fitted to the outer periphery of the inboard side end of the shaft portion of the hub ring. ,
The sealing means on the outboard side end is attached to the outer member and has a contact seal whose tip contacts the hub wheel, and between the outer member and the hub wheel outside the bearing space with respect to the contact seal. The labyrinth seal gap formed in
An outer surface portion of the hub wheel shaft portion that extends from the outboard side end to the side surface of the hub flange increases in diameter as it reaches the outboard side, and a cross-section arc-shaped corner arc that continues from the shaft end surface. And a base arc surface having a cross-sectional arc shape that extends from the corner arc surface to the side surface of the hub flange, and the outer peripheral inner surface and end surface of the outer member are close to the corner arc surface. A wheel bearing device, wherein a gap having an L-shaped cross-section serving as the labyrinth seal gap is formed between the corner arc surface and the outer member. In Claim 1, the pitch circle diameter of the rolling element row on the outboard side is made larger than the pitch circle diameter of the rolling element row on the inboard side, and the number of rolling elements in the rolling body row on the outboard side is Wheel bearing device in which the number of rolling elements in the side rolling element row is increased.

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