JP2008168664A - Bearing device for wheel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bearing device for a wheel which is suitable for being used as an axle unit for a large vehicle and capable of constantly and correctly detecting the rotation of a wheel without changing the positional relationship between a magnetic encoder and a magnetic sensor by preventing an outer ring from being axially moved with respect to a housing. <P>SOLUTION: The bearing device 1 for the wheel comprises double-row rolling bearings 2 and a housing 7 for fitting an annular hub 34 with an outer ring 4 of the rolling bearings 2 press-fitted to its inner circumference, and a magnetic encoder 17 is provided at the housing 7. The inner circumferential surface 11 of the housing is formed in a stepped cylindrical surface composed of a press-fitting face 11b with the outer ring 4 press-fitted, and a small diameter face 11c having a diameter smaller than that of the press-fitting face 11b continuous to the press-fitting face 11b via a step 11c. The outer ring 4 press-fitted to the press-fitting face part 11b is width-squeezed by the step 11c and a fixing member 13 fixed to the inner circumference of the housing 7. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a wheel bearing device used as an axle unit for large vehicles such as trucks and buses.

As an axle unit for a large vehicle, for example, a structure disclosed in Patent Document 1 is known. As shown in FIG. 3, the axle unit includes a unitized double row rolling bearing 2 and an annular housing 7 in which an outer ring 4 of the rolling bearing 2 is fitted to the inner periphery. To which a hub 34 and a brake rotor 35 are attached. Wheels (not shown) are attached to the hub 34.
Japanese Patent Laid-Open No. 2003-312205

  In this type of axle unit, the outer ring 4 of the rolling bearing 2 is usually fitted into the inner periphery of the housing 7 by press fitting. In that case, when the axle unit is subjected to a high load, a retaining ring 15 for restricting the axial movement of the outer ring 4 is attached to the housing 7 in order to prevent the outer ring 4 from creeping and coming off in the axial direction. It is done.

  The retaining ring 15 is fitted into the annular groove 13 formed on the inner periphery of the housing 7 by using the elasticity of the retaining ring 15, and the width of the annular groove 13 is set so that the fitting is performed smoothly. The width of the retaining ring 15 is slightly narrower than that. For this reason, there is a slight axial gap between the retaining ring 15 and the housing 7 with the retaining ring 15 attached, and the outer ring 4 may move relative to the housing 7 by this gap. is there.

Many recent automobiles are equipped with an anti-lock brake device (ABS) in order to obtain steering stability. In an automobile equipped with an anti-lock brake device, an ABS sensor that detects tire lock is provided in the axle unit. The ABS sensor includes a magnetic encoder attached to the rotation side member of the axle unit and a magnetic sensor attached to the fixed side member so as to face the magnetic encoder.
Although there is no specific explanation, Patent Document 1 also shows A which is considered to be a magnetic encoder of a rotation detection device such as an ABS sensor. It is attached to the end of the inboard side of the housing 7 which is a rotation side member. When A is an axial type magnetic encoder, the magnetic sensor B is provided on the fixed member at a predetermined distance in the axial direction from the magnetic encoder A as indicated by a two-dot chain line. In the example of FIG. 3, the fixed side member is a knuckle C.

  However, for the reason described above, when the outer ring 4 moves in the axial direction with respect to the housing 7 within the gap between the retaining ring 15 and the housing 7, the members on the vehicle body side of the outer ring 4 together with the outer ring 4 also move in the axial direction. The distance between the magnetic encoder A and the magnetic sensor B changes, and the rotation detection device cannot accurately detect the rotation of the wheel. Even when A is a radial magnetic encoder, the angle between the magnetic encoder A and the magnetic sensor B changes, so that the rotation detection device cannot accurately detect the rotation of the wheel. When the detection accuracy of the rotation detection device is thus reduced, there is a concern that the antilock brake device will not operate correctly.

  The object of the present invention is suitable for use as an axle unit for a large vehicle, and by preventing the outer ring from moving in the axial direction with respect to the housing, the positional relationship between the magnetic encoder and the magnetic sensor does not change. An object of the present invention is to provide a wheel bearing device that can always accurately detect the rotation of a wheel.

  A wheel bearing device according to the present invention includes a double row rolling bearing, and an annular hub mounting housing in which an outer ring of the rolling bearing is press-fitted into the inner periphery, and the housing is provided with a magnetic encoder. The inner peripheral surface of the housing has a stepped cylindrical surface shape including a press-fitting surface portion into which the outer ring is press-fitted, and a small-diameter surface portion having a smaller diameter than the press-fitting surface portion continuing to the press-fitting surface portion through a step portion. The outer ring formed and press-fitted into the press-fitting surface portion is width-tightened by the stepped portion and a fixing member fixed to the inner periphery of the housing.

  This wheel bearing device is used as an axle unit by attaching a hub and a brake rotor to a hub mounting housing. Since the outer ring of the rolling bearing is tightened by the step portion of the inner peripheral surface of the housing and the fixing member fixed to the inner periphery of the housing, the outer ring does not move in the axial direction with respect to the housing. The positional relationship with the magnetic sensor that faces is not changed. Therefore, the rotation of the wheel can always be accurately detected.

In the present invention, the fixing member is a ring-shaped member having a male screw formed on the outer periphery, and is preferably screwed to a female screw portion provided on the inner periphery of the housing.
When the fixing member is as described above, the fixing member can be easily fixed to the inner periphery of the housing, and the outer ring can be securely tightened by the fixing member.

The magnetic encoder has an L-shaped cross section including an end surface abutting portion that abuts on the axial end surface of the housing, and an outer peripheral fitting portion that fits to the outer peripheral surface of the housing following the outer peripheral edge of the end surface abutting portion. It is preferable that an annular multi-pole magnet having a plurality of magnetic poles arranged in the circumferential direction is formed on the end surface abutting portion of the core metal.
When the magnetic encoder is configured as described above, the magnetic encoder can be provided at the axial end of the housing even if the fixing member is fixed near the axial end of the inner periphery of the housing. Therefore, the axial length of the housing 7 can be shortened. Further, when the magnetic encoder is an axial type in which an annular multipolar magnet is formed on the end surface contact portion of the core metal, the magnetic sensor is provided at a position facing the multipolar magnet in the axial direction. A rotation detection device including a magnetic sensor can be provided without being bulky in the radial direction.

  A wheel bearing device according to the present invention includes a double row rolling bearing, and an annular hub mounting housing in which an outer ring of the rolling bearing is press-fitted into an inner periphery, and a magnetic encoder is provided in the housing. The inner peripheral surface of the housing is formed in a stepped cylindrical surface shape including a press-fitting surface portion into which the outer ring is press-fitted, and a small-diameter surface portion having a smaller diameter than the press-fitting surface portion continuing to the press-fitting surface portion via a stepped portion. Since the outer ring press-fitted into the press-fitting surface portion is tightened with the stepped portion and a fixing member fixed to the inner periphery of the housing, it is suitable for use as an axle unit for a large vehicle, In addition, the outer ring can be prevented from moving in the axial direction with respect to the housing, so that the rotation of the wheel can always be accurately detected without changing the positional relationship between the magnetic encoder and the magnetic sensor. That.

  An embodiment of the present invention will be described with reference to FIG. This embodiment is an outer ring rotating type, and shows a state where it is used for an axle unit for a driven wheel of a large vehicle such as a truck or a bus. 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 1 is composed of a double row rolling bearing 2 and a hub mounting housing 7 fitted to the outer periphery of the rolling bearing 2. The rolling bearing 2 includes two inner rings 3 each having a raceway surface 3a on the outer peripheral surface, an outer ring 4 having a double-row raceway surface 4a facing the raceway surface 3a of the inner ring 3, and the inner and outer rings. The rolling element 5 of the double row | line | column integrated between 3 and 4 is provided. In the case of this embodiment, the rolling elements 5 are tapered rollers, and double rows of tapered rollers are arranged in a back surface combination and are held by the cage 6 for each row. Both ends of the bearing space between the inner ring 3 and the outer ring 4 are sealed by seals 8 and 9, respectively.

  The housing 7 is an annular member, and an inner peripheral surface 11 thereof continues to a female screw portion 11a at an inboard side end portion in which a female screw is formed on the inner periphery, and an outboard side of the female screw portion 11a. A stepped cylindrical surface is formed of a press-fitting surface portion 11b into which the outer ring 4 is press-fitted, and a small-diameter surface portion 11d having a smaller diameter than the press-fitting surface portion 11b continuing to the outboard side through the step portion 11c. . Bolt holes 12 for attaching the hub and the brake rotor are provided at a plurality of locations in the circumferential direction on the end face of the housing 7 on the outboard side.

  The rolling bearing 2 is incorporated into the housing 7 by press-fitting the outer ring 4 into the inner peripheral surface press-fitting surface portion 11 b of the housing 7 from the inboard side. A fixing member 13, which is a ring-shaped member having a male screw formed on the outer periphery, is screwed to the inner peripheral surface press-fitting surface portion 11 b of the housing 7 while being pressed against the inboard side end surface of the outer ring 4. As a result, the outer ring 4 is tightened by the inner peripheral surface step portion 11 c of the housing 7 and the fixing member 13.

  A magnetic encoder 17 is fixedly provided at the inboard side end of the housing 7. The magnetic encoder 17 is configured as a rotation detection device 22 in combination with a magnetic sensor 21 described later. The rotation detection device 22 is used as an ABS sensor for detecting tire lock, for example, and an antilock brake device is operated based on the detection result.

  The magnetic encoder 17 is of an axial type, and as shown in the partially enlarged view of FIG. 1B, an end surface contact portion 18a that contacts the inboard side end surface of the housing 7, and this end surface contact portion 18a. An annular cored bar 18 having an L-shaped cross section consisting of an outer peripheral fitting part 18b fitted to the outer peripheral surface of the housing 7 is provided following the outer peripheral edge of the housing 7. The end face abutting part 18a of the cored bar 18 has many A polar magnet 19 is formed. The multipolar magnet 19 is an annular member having a plurality of magnetic poles arranged in the circumferential direction. Here, a rubber mixed with a magnetic material is vulcanized and bonded to the inboard side surface of the core metal end surface contact portion 18a. It is a magnetized rubber magnet. Instead of the rubber magnet, a plastic magnet or a sintered magnet may be provided.

  The magnetic sensor 21 is attached to the fixed side member of the axle unit so as to face the inboard side surface of the multipolar magnet 19. In this embodiment, the fixed side member is the base 31a of the fixed shaft 31 fixed to the knuckle. As the magnetic encoder 17 rotates, the magnetic sensor 21 detects the magnetic poles of the multipolar magnet 19 that crosses the front of the magnetic sensor 21, so that the rotation detector 22 detects the rotation of the wheel attached to the axle unit. .

  When the wheel bearing device 1 is assembled as, for example, an axle unit for a driven wheel of a truck, the fixed shaft 31 is inserted into the inner periphery of the inner ring 3, and a nut 32 is attached to a screw portion 31b on the distal end side of the fixed shaft 31. The inner ring 3 is then tightened with the nut 32 and the large-diameter portion 31c on the base side of the fixed shaft 31. Further, the hub 34 and the brake rotor 35 are attached to the housing 7 by bolts 33 screwed into the bolt holes 12. A wheel (not shown) is attached to the hub 34 with hub bolts 36.

  The outer ring 4 of the rolling bearing 2 is tightened in width by the inner peripheral surface step portion 11 c of the housing 7 and the fixing member 13 fixed to the inner periphery of the housing 7. There is no movement, and the distance between the magnetic encoder 17 and the magnetic sensor 21 facing the magnetic encoder 17 is constant. Therefore, the rotation detection device 22 can always detect the rotation of the wheel with high accuracy. Also, the antilock brake device always operates correctly.

  Since the magnetic encoder 17 has a shape that fits only on the outer peripheral surface of the peripheral surface of the housing 7, the magnetic encoder 17 can be attached to the housing 7 even if the fixing member 13 is fixed near the axial end of the inner periphery of the housing 7. It can be provided at the axial end. Therefore, the axial length of the housing 7 can be shortened. Further, since the magnetic encoder 17 is an axial type and the magnetic sensor 21 is provided at a position facing the multipolar magnet 19 in the axial direction, the rotation detector 22 can be provided without being bulky in the radial direction. it can.

  FIG. 2 shows a different embodiment. In this embodiment, a hardened surface hardening layer 26 is provided on the inner peripheral surface press-fitting surface portion 11b and the step portion 11c, which are bearing fitting surfaces of the housing 7. The hardness of the surface hardened layer is preferably HRC50 or more. When the hardened surface layer 26 is provided in this manner, wear can be suppressed by contact with the press-fitting surface portion 11b and the stepped portion 11c on the inner peripheral surface of the housing 7. The surface hardened layer 26 may be provided only on the press-fit surface portion 11b.

In this embodiment, the magnetic encoder is an axial type, but the magnetic encoder may be a radial type. When the magnetic encoder is a radial type, it is possible to eliminate the change in angle between the magnetic encoder and the magnetic sensor when the outer ring 4 moves in the axial direction. Therefore, also in this case, the rotation detection device can always detect the rotation of the wheel with high accuracy.
Further, in this embodiment, the rolling bearing 2 is a tapered roller bearing type, but may be a ball bearing type such as an angular ball bearing.
In this embodiment, the wheel bearing device 1 is used for a driven wheel axle unit. However, the wheel bearing device of the present invention can also be applied to a drive wheel axle unit.

(A) is sectional drawing of the axle unit incorporating the wheel bearing apparatus concerning embodiment of this invention, (B) is the IB section enlarged view. It is sectional drawing of the axle unit incorporating the wheel bearing apparatus concerning different embodiment of this invention. It is sectional drawing of the conventional axle unit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Wheel bearing apparatus 2 ... Rolling bearing 3 ... Inner ring 4 ... Outer ring 7 ... Housing 11 ... Outer ring inner peripheral surface 11b ... Press-fit surface part 11c ... Step part 11d ... Small diameter part 13 ... Fixed member 17 ... Magnetic encoder 18 ... Core metal 18a ... end face contact part 18b ... outer periphery fitting part 19 ... multipolar magnet 21 ... magnetic sensor 31 ... fixed shaft 34 ... hub 35 ... brake rotor

Claims (3)

A wheel bearing device including a double row rolling bearing and an annular hub mounting housing in which an outer ring of the rolling bearing is press-fitted into the inner periphery, and a magnetic encoder is provided in the housing.
The inner peripheral surface of the housing is formed in a stepped cylindrical surface shape including a press-fitting surface portion into which the outer ring is press-fitted, and a small-diameter surface portion having a smaller diameter than the press-fitting surface portion continuing to the press-fitting surface portion through a step portion. The wheel bearing device, wherein the outer ring press-fitted into the surface portion is tightened by the step portion and a fixing member fixed to the inner periphery of the housing.   2. The wheel bearing device according to claim 1, wherein the fixing member is a ring-shaped member having a male screw formed on an outer periphery thereof, and is screwed into a female screw portion provided on the inner periphery of the housing.   3. The magnetic encoder according to claim 1, wherein the magnetic encoder includes an end surface abutting portion that abuts on an end surface in the axial direction of the housing, and an outer periphery fitting that engages with the outer peripheral surface of the housing following the outer peripheral edge of the end surface abutting portion. An annular multi-pole magnet having a plurality of magnetic poles arranged in the circumferential direction is formed on the end surface abutting portion of the metal core. A certain wheel bearing device.

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