JP2014105786A - Wheel bearing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wheel bearing device achieving a reduction in torque while securing a seal function.SOLUTION: In a hub unit 1 comprising an outer ring 2 fixed to a knuckle 20 and an inner ring 3 rotatably supported to the outer ring 2, a flange 3c formed protrusively toward the outside in the radial direction and attaching a wheel is formed at one end of the inner ring 3 in the axial direction, a seal member 7 fit to an end of an internal peripheral face at the flange 3c side of the outer ring 2 and constituting a bearing internal space 6 by sealing an annular space S1 between the outer ring and the inner ring 3 is arranged, and the seal member 7 has an annular lip 72d composed of an elastic body and continuously slide-contacting with a side face 3d of the flange 3c. In the lip 72d, a fastening margin of a portion arranged in the center part H1 set in a region in the vicinity of the center in the vertical direction in a state in which the hub unit 1 is mounted on a vehicle is set smaller than fastening margins of portions arranged in an upper part H2 set in a region above the center part H1 and in a lower part H3 set in a region below the center part H1.

Description

  The present invention relates to a wheel bearing device.

Conventionally, for example, in a wheel bearing device that supports a vehicle wheel, an outer ring is fixed to a vehicle body side member on the vehicle inner side, and a vehicle outer side wheel is attached to the inner ring. Since this wheel bearing device is used in a bad environment affected by rainwater, muddy water, etc. (hereinafter collectively referred to as “muddy water”), the annular space between the outer ring and the inner ring is pivoted. A bearing internal space is configured by sealing with seal members at both ends in the direction.
The inner ring is formed with a flange for projecting radially outward at an end on the vehicle outer side to attach the wheel. A seal member mounted on the outer side of the vehicle has a metal core fitted and fixed to an inner peripheral end of the outer ring on the flange side, and a lip made of an elastic body and vulcanized and bonded to the metal core. The lip has a predetermined tightening allowance and is slidably contacted with the side surface of the flange to prevent muddy water from entering the bearing internal space.

  In recent years, from the viewpoint of improving the fuel efficiency of vehicles, there has been an increasing demand for lower torque for wheel bearing devices. Therefore, in the wheel bearing device, assuming that the muddy water splashed by the wheel falls from above the bearing in the vehicle mounted state, the tightening allowance of the lower portion of the lip is smaller than the tightening allowance of the upper portion. It is set to reduce torque. (For example, see Patent Document 1)

JP 2012-154367 A

  However, in the above-described wheel bearing device, muddy water that travels on the outer peripheral surface of the outer ring out of the muddy water that the wheel jumps in enters near the lip from the upper side of the opening between the flange of the inner ring and the end surface of the outer ring. The infiltrated muddy water moves in the circumferential direction and downward, but does not immediately drain from the lower side of the opening to the outside of the bearing, and stays near the lower lip. As a result, in the wheel bearing device, the muddy water may enter the bearing internal space from the sliding contact portion of the lower lip having a small tightening allowance, thus reducing the sealing function. Therefore, it has been a problem to reduce the torque of the wheel bearing device while ensuring a sealing function.

  The present invention has been made to solve such problems, and an object of the present invention is to provide a wheel bearing device capable of reducing torque while ensuring a sealing function.

  In order to solve the above-mentioned problems, the structural feature of the wheel bearing device according to claim 1 is that an outer ring fixed to a vehicle body-side member of a vehicle and an outer ring that is rotatable about an axis via a rolling element. An inner ring to be supported, and a flange for attaching a wheel is formed at one end of the inner ring in the axial direction so as to protrude radially outward, and the inner peripheral surface end of the outer ring on the flange side And a seal member which seals an annular space between the outer ring and the inner ring to form a bearing inner space, and the seal member is made of an elastic body and continuously contacts the side surface of the flange. In the wheel bearing device having an annular lip, in the vehicle mounted state, the lip has a tightening margin of a portion arranged in a central portion that sets a region near the center in the vertical direction, and a region above the central portion. Upper part to set and Is that is set to be smaller than the interference of the portion arranged in the lower setting the area below the serial central portion.

  According to the wheel bearing device of claim 1, the lip has a tightening allowance of a portion arranged in the central portion that is less affected by muddy water that the wheel jumps up, than a tightening allowance of portions arranged in the upper and lower portions. Therefore, the torque can be reduced while ensuring the sealing function.

  A structural feature of the wheel bearing device according to claim 2 is that the lip is arranged in the upper part and the lower part in the axial direction of the part arranged in the central part in the vertical direction in a vehicle-mounted state. That is, it is shorter than the length of the portion to be formed.

  According to the wheel bearing device of the second aspect, since the length of the portion where the lip is disposed at the central portion is shorter than the length of the portion disposed at the upper and lower portions, the lip is disposed at the central portion of the lip. The tightening allowance of the portion to be set is set smaller than the tightening allowance of the portion arranged at the upper part and the lower part, and the torque can be reduced while ensuring the sealing function.

  ADVANTAGE OF THE INVENTION According to this invention, the wheel bearing apparatus which can aim at low torque can be provided, ensuring a sealing function.

It is sectional drawing of the axial direction of the hub unit provided with the wheel bearing apparatus which is one Embodiment of this invention. It is the A section enlarged view of FIG. It is the B section enlarged view of FIG. It is sectional drawing of the axial direction of a sealing member when a lip is a no-load state.

DESCRIPTION OF EMBODIMENTS Hereinafter, an embodiment in which a wheel bearing device of the present invention is embodied will be described with reference to the drawings.
FIG. 1 is a sectional view in the axial direction of a hub unit 1 including a wheel bearing device according to an embodiment of the present invention. This will be described with reference to FIG. In the following description, the vehicle inner side is the axle side and indicates the left side in the following drawings, and the vehicle outer side is the side on which the wheels are attached and the right side in the following drawings.

  The hub unit 1 (wheel bearing device) is, for example, for a front wheel (for a drive shaft) of a front wheel drive vehicle, and has a double-row outward angular ball bearing structure. Specifically, the hub unit 1 includes an outer ring 2 fixed to a knuckle 20 that is a vehicle body side member on the vehicle inner side, and a vehicle outer side wheel (not shown) arranged coaxially with the axis 11 of the outer ring 2. An inner ring 3 (inner ring) to be attached, an inner ring 4 fitted on the outer peripheral surface of a fitting portion 3a formed integrally with the vehicle inner side end of the inner shaft 3, an outer ring 2, the inner shaft 3 and the inner ring 4 There are provided double-row balls 5 (rolling elements) arranged in the circumferential direction between them.

  On the inner peripheral surface of the outer ring 2, a raceway surface 2a for balls 5 arranged on the vehicle inner side and a raceway surface 2b for balls 5 arranged on the vehicle outer side are formed. A vehicle mounting flange portion 2 c that protrudes radially outward and is fixed to the knuckle 20 is formed on the outer peripheral surface of the outer ring 2. As a material of the outer ring 2, for example, high carbon steel “S55C” is used.

  A raceway surface 3b that faces the raceway surface 2b of the outer ring 2 is formed on the outer peripheral surface of the inner shaft 3, and a flange 3c that protrudes radially outwardly from the raceway surface 3b and is attached to a wheel. Is formed. Between the flange 3c and the end surface of the outer ring 2, an opening 9 is formed in an annular shape as a minute gap (for example, 1 mm) in order to prevent muddy water from entering the inside of the bearing. For example, high carbon steel “S55C” is used as the material of the inner shaft 3.

  The inner ring 4 is press-fitted into the fitting portion 3a and integrated with the fitting portion 3a. On the outer peripheral surface of the inner ring 4, a raceway surface 4 a that faces the raceway surface 2 a of the outer ring 2 is formed. As a material of the inner ring 4, for example, a high carbon chrome bearing steel “SUJ2” is used.

  Between the outer ring 2, the inner shaft 3 and the inner ring 4, an annular space S1 for arranging balls 5 as rolling elements is formed. In the annular space S1, an annular seal member 7 is attached to the vehicle outer side, and an annular seal member 8 is attached to the vehicle inner side. The seal member 7 and the seal member 8 constitute a bearing internal space 6 that is sealed in a state in which relative rotation between the outer ring 2 and the inner shaft 3 and the inner ring 4 is allowed.

  FIG. 2 is an enlarged view of part A in FIG. FIG. 3 is an enlarged view of a portion B in FIG. FIG. 4 is a sectional view in the axial direction of the seal member 7 when the lip 72d is in an unloaded state. This will be described with reference to FIGS. 2, 3 and 4.

  As shown in FIGS. 2 and 3, the seal member 7 includes an annular cored bar 71 and an annular seal 72.

  The cored bar 71 is a cylindrical cylindrical portion 71a that is press-fitted to the inner end of the outer ring 2 on the vehicle outer side, and a circle that extends radially inward from the end of the cylindrical portion 71a on the vehicle outer side. It consists of a plate part 71b. As a material of the core bar 71, for example, SPCC of a cold-rolled steel sheet that has been rust-proofed is used.

  A seal 72 made of an elastic body is vulcanized and integrated with the metal core 71. The seal 72 includes a fitting portion 72a, a base portion 72b, and a lip portion 72c. The fitting portion 72a is formed at the end of the cylindrical portion 71a on the vehicle outer side with a predetermined tightening margin between the fitting portion 72a and the outer ring 2. The fitting portion 72a is fitted into the inner peripheral surface of the outer ring 2 together with the cylindrical portion 71a by press fitting. Has been fixed. The base 72b extends from the fitting portion 72a along the disc portion 71b toward the outer circumference of the inner shaft 3 on the raceway surface side. The lip portion 72c extends from the base portion 72b toward the outer periphery of the raceway surface side of the inner shaft 3, and includes a lip 72d and radial lips 72e and 72f. As a material of the seal 72, for example, nitrile rubber is used.

  The lip 72d extends from the base portion 72b to the flange 3c side in the axial direction and the outer ring 2 side in the radial direction (outward side in the radial direction). The tip of the lip 72d is in sliding contact with the side surface 3d on the vehicle inner side of the flange 3c over the entire circumference. A lip 72g indicated by a broken line in FIG. 2 indicates a state where the lip 72g is not in sliding contact with the side surface 3d, that is, a no-load state. The difference in the length of the lip 72d in the axial direction from the lip 72g serves as a tightening margin, and this serves as a pressing force for pressing the side surface 3d to ensure a sealing function.

  As shown in FIG. 4, the lip 72d has a central portion H1 that sets a region near the center in the vertical direction of the vehicle mounted state, an upper portion H2 that sets a region above the central portion H1, and a lower portion than the central portion H1. The ratio of the area of the lower part H3 that sets the area is, for example, 5: 2: 1. When the lip 72d is not attached to the hub unit 1, the length L1 in the axial direction of the portion arranged in the central portion H1 is set to 2.8 mm, for example, and the fastening margin is set to 0.5 mm, for example. The lip 72d is formed such that the axial length L2 of the portions arranged in the upper part H2 and the lower part H3 is 3.0 mm, for example, and the interference is 0.7 mm, for example. As a result, the lip 72d is set so that the tightening allowance of the portion disposed in the central portion H1 is smaller than the tightening allowance of the portions disposed in the upper portion H2 and the lower portion H3. From these, the lip 72d arranged in the upper part H2 and the lower part H3 that are affected by the muddy water that the wheel jumps up has a predetermined allowance to ensure a desired sealing function. On the other hand, the lip 72d disposed in the central portion H1 that is less affected by the muddy water that the wheel jumps up has a small tightening margin and a low torque.

  Here, since it is necessary to specify the circumferential position of the lip 72d when the hub unit 1 is assembled, the hub unit 1 includes the end portion of the outer peripheral surface of the outer ring 2 which is a mating surface between the outer ring 2 and the seal member 7 and Protrusions are provided on each of the outer peripheral surfaces of the lip 72d to facilitate phase alignment in the circumferential direction.

  The radial lip 72e is positioned outward in the axial direction from the radial lip 72f. The radial lips 72e and 72f extend from the base portion 72b inward in the radial direction, have a predetermined tightening margin on the outer periphery of the inner shaft 3 on the raceway surface side, and are in sliding contact with the entire periphery.

  As shown in FIG. 2, the muddy water that travels on the outer peripheral surface of the outer ring 2 out of the muddy water that the wheel jumps up enters the vicinity of the lip 72d disposed inside the bearing from the opening 9 as indicated by a two-dot chain line F1. The muddy water pool W1. Here, the lip 72d disposed in the upper portion H2 corresponding to the reservoir W1 has a predetermined tightening allowance to ensure a sealing function, and thus prevents muddy water from entering the bearing internal space 6.

  Then, the muddy water W1 moves in the vicinity of the lip 72d in the circumferential direction and downward in the vertical direction, and reaches the vicinity of the lip 72d on the lower side of the opening 9, as shown in FIG. Become. Part of the muddy water W2 is drained from the opening 9 to the outside of the bearing as indicated by a two-dot chain line F2. However, most of the muddy water W2 is not discharged immediately because the opening 9 is a minute gap, but stays near the lip 72d. Here, since the lip 72d disposed in the lower portion H3 corresponding to the reservoir W2 has a predetermined tightening allowance to ensure a sealing function, entry of muddy water into the bearing internal space 6 is prevented.

  As described above, according to the hub unit 1 according to the present embodiment, it is possible to reduce the torque while ensuring the sealing function.

In addition, this invention is not limited to this embodiment, In the range which does not deviate from the summary of this invention, it can implement with a various form.
In the present embodiment, the rolling elements are balls 5, but the invention is not limited to this. For example, the rolling elements may be applied to a tapered roller configuration.

  In the above embodiment, the configuration of the driving wheel has been described. However, the present invention can also be applied to a driven wheel.

  Moreover, in the said embodiment, although the length of the part arrange | positioned at the upper part H2 and the lower part H3 of the lip 72d was made into the length L2, it is not restricted to it, For example, the influence of the muddy water which a wheel jumps up is large You may apply to the structure where the length of the part arrange | positioned at the upper part H2 is longer than the length of the part arrange | positioned at the lower part H3.

  In the above embodiment, the length of the lip 72d in FIG. 4 is described as forming an inflection point at the boundary between the central portion H1 and the upper portion H2, and the boundary between the central portion H1 and the lower portion H3. Instead, for example, the present invention may be applied to a configuration that changes more gently in the circumferential direction.

1: hub unit (wheel bearing device), 2: outer ring, 2c: vehicle mounting flange, 3: inner shaft (inner ring), 3c: flange, 3d: side surface, 4: inner ring, 5: ball (rolling element), 6: Bearing internal space, 7, 8: Seal member, 9: Opening part, 11: Axis, 71: Core metal, 71a: Cylindrical part, 71b: Disk part, 72: Seal, 72a: Fitting part, 72b: Base, 72c: Lip part, 72d: Lip, 72e, 72f: Radial lip, F1, F2: Muddy water flow, H1: Center part, H2: Upper part, H3: Lower part, L1: Length of lip center part, L2: Length of upper and lower lip, S1: annular space, W1, W2: mud pool

Claims (2)

An outer ring that is fixed to a vehicle body side member of the vehicle, and an inner ring that is supported by the outer ring so as to be rotatable about an axis via a rolling element, and is radially outward at one end in the axial direction of the inner ring. A flange for attaching a wheel is formed to project, and is fitted to an inner peripheral surface end portion of the outer ring on the flange side, sealing an annular space between the outer ring and the inner ring to thereby make a bearing inner space. Comprising a sealing member,
In the wheel bearing device, the seal member is formed of an elastic body and has an annular lip that continuously contacts the side surface of the flange.
In the vehicle mounted state, the lip has a tightening margin of a portion arranged in a central portion that sets an area near the center in the vertical direction, an upper portion that sets an area above the central portion, and a lower side than the central portion. A bearing device for a wheel, characterized in that it is set smaller than a tightening allowance of a portion arranged in a lower portion for setting an area.   The lip is formed such that, in a vehicle-mounted state, the length in the axial direction of the portion arranged in the central portion in the vertical direction is shorter than the length of the portions arranged in the upper portion and the lower portion. The wheel bearing device according to claim 1.

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