Wheel bearing device

Abstract

To provide a bearing device for wheel capable of improving muddy water resistant performance and detecting temperature rise of a bearing by a pulser ring mounted on the bearing.SOLUTION: A pulser ring 21 made of shape memory alloy is mounted on an end portion of a rotation-side member out of an outer member 4 and an inner member 3, the pulser ring 21 is composed of a cylindrical portion 21a fitted to the end portion of the rotation-side member, and a vertical plate portion 21b extending from the cylindrical portion 21a toward a stationary-side member and having a detected portion in a circumferential direction. A seal lip 23 having an interference to the stationary-side member is disposed on a tip of the vertical plate portion 21b, the vertical plate portion 21b is deformed in a direction to change a distance to a rotation sensor when the vertical plate portion 21b is over a shape recovery temperature, and abnormal temperature rise of the bearing is detected on the basis of output change of the rotation sensor 22 based on the deformation.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] This invention relates to a wheel bearing device that supports a vehicle such as an automobile so that it can rotate freely relative to a suspension system, and in particular to a wheel bearing device that uses a pulser ring that detects the rotational speed of the bearing to improve the muddy water resistance of the seal attached to the bearing and can also detect temperature increases in the bearing. [Background technology]

[0002] As shown in Figure 7, for example, a wheel bearing device includes an outer member 52 having double-row outer raceway surfaces 52a, 52a integrally formed on its inner periphery, an inner member 51 having double-row inner raceway surfaces 54a, 54a formed on its outer periphery that face the double-row outer raceway surfaces 52a, 52a, and double-row rolling elements (tapered rollers) 53, 53 accommodated between the raceway surfaces 54a, 52a of the inner member 51 and the outer member 52 via cages 58, 58 so as to be able to roll freely.

[0003] Seals 59 and 60 are fitted to the opening of the annular space formed between the outer member 52 and the inner member 51 to prevent leakage of the grease sealed inside the bearing and to prevent the intrusion of rainwater, dust, etc. from the outside.

[0004] Further, in the past, there have been devices equipped with a pulser ring to detect the rotation of the wheel bearing and the axle (Patent Document 1, Patent Document 2).

[0005] Furthermore, there is also a device that combines a temperature detection sensor to detect failures in a wheel bearing device (Patent Document 3). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 5897411 [Patent Document 2] Japanese Patent Application Laid-Open No. 2012-173205 [Patent Document 3] Patent No. 4259395 Summary of the Invention [Problem to be solved by the invention]

[0007] Incidentally, wheel bearing devices used in trucks and the like are used in long driving distances and in harsh environments, so seals are required to have even greater muddy water resistance.

[0008] Furthermore, when a temperature detection sensor is incorporated to detect a failure in a wheel bearing device, as in Patent Document 3, there is a problem that the cost increases accordingly.

[0009] Therefore, this invention focuses on the pulser ring that detects the rotational speed of the bearing, and aims to improve the seal's muddy water resistance and also detect temperature increases in the bearing by using the pulser ring attached to the bearing. [Means for solving the problem]

[0010] The wheel bearing device of the present invention that solves the above-mentioned problems comprises an outer member having double-row outer raceway surfaces integrally formed on its inner periphery, an inner member having double-row inner raceway surfaces formed on its outer periphery that face the double-row outer raceway surfaces, double-row rolling elements housed between the raceway surfaces of the inner member and the outer member via a cage so as to be able to roll freely, and a seal attached to an opening of an annular space formed between the outer member and the inner member, and further comprising: a pulser ring attached to the rotating member of the outer member or the inner member; and a rotation sensor arranged opposite to a portion to be detected of the pulser ring. the pulsar ring comprises a cylindrical portion that fits onto the end of the rotating-side member, and a standing portion that extends from the cylindrical portion towards the fixed-side member and has a detection portion in the circumferential direction, and a seal lip that has an interference fit with the fixed-side member is provided at the tip of the standing portion, and of the cylindrical portion and standing portion that make up the pulsar ring, at least the standing portion is formed from a shape memory alloy, and when the shape recovery temperature of the standing portion is exceeded, the standing portion deforms in a direction that changes the distance from the rotation sensor, and an abnormal temperature rise of the bearing is detected based on a change in output of the rotation sensor due to this deformation.

[0011] The direction of deformation of the upright portion of the pulsar ring may be set so that the interference of the seal lip provided at the tip of the upright portion with the fixed member becomes larger or smaller.

[0012] If the detected portion of the pulser ring is configured by openings provided at equal intervals around the circumference of the upright portion, a non-magnetic rubber material that covers the openings is provided on the side of the upright portion opposite the position of the rotation sensor.

[0013] The non-magnetic rubber material that closes the opening can be formed integrally with the seal lip at the tip of the upright plate portion. [Effects of the Invention]

[0014] As described above, the wheel bearing device of this invention has a pulser ring attached to the rotating member of the outer and inner members, which is composed of a cylindrical portion that fits onto the end of the rotating member, and a vertical portion that extends from this cylindrical portion towards the fixed member and has a detectable portion in the circumferential direction.By providing a seal lip at the tip of this vertical portion that has an interference fit with the fixed member, the sealing performance of the bearing is improved, and the sealing structure can be simplified by reducing the number of lips in the sealing parts, which is expected to result in cost reduction.

[0015] Of the cylindrical portion and the upright portion that make up the pulser ring, at least the upright portion is formed from a shape memory alloy, and when the upright portion exceeds its shape recovery temperature, the upright portion deforms in a direction that changes the distance from the rotation sensor, making it possible to detect abnormal temperature increases in the bearing based on changes in the output of the rotation sensor due to the deformation of the upright portion.

[0016] Furthermore, if the deformation direction of the standing plate portion is set so that the interference between the seal lip at the tip of the standing plate portion and the fixed side member is increased, the amount of heat generated between the seal lip at the tip of the standing plate portion and the fixed side member due to temperature rise will increase, making it possible to more sensitively detect abnormal temperature rises in the bearing. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a vertical cross-sectional view showing an embodiment of a wheel bearing device of the present invention. [Figure 2] 1 is an enlarged view of a double-row tapered roller bearing constituting a wheel bearing device of the present invention. [Figure 3] 4 is an enlarged vertical cross-sectional view showing a state before deformation of a pulser ring in the wheel bearing device of the present invention. FIG. [Figure 4] 4 is an enlarged vertical cross-sectional view showing a state after deformation of the pulsar ring in the wheel bearing device of the present invention. FIG. [Figure 5] 3 is a side view of a pulsar ring in the wheel bearing device of the present invention. FIG. [Figure 6]FIG. 10 is an enlarged vertical cross-sectional view showing a state before deformation of a pulsar ring in a wheel bearing device according to another embodiment of the present invention. [Figure 7] FIG. 10 is a vertical cross-sectional view showing a conventional wheel bearing device. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. In the following description, the side that is closer to the outside of the vehicle when assembled to the vehicle will be referred to as the outer side (left side in FIG. 1), and the side that is closer to the center will be referred to as the inner side (right side in FIG. 1).

[0019] The wheel bearing device shown in Figure 1 is mounted on an axle for a driven wheel and rotatably supports a wheel (not shown). The double-row tapered roller bearing 1 that constitutes this wheel bearing device comprises a pair of inner members (fixed members) 3, 3 fitted onto the outside of an axle 2, an outer member (rotating member) 4 integrally formed with a mounting flange 4b ​​for mounting a wheel (not shown) at one end of its outer periphery, and double-row tapered rollers 5, 5 housed between the inner member 3 and the outer member 4. A hub 6 for mounting the wheel and a brake rotor 7 are fixed to the mounting flange 4b ​​with bolts 8. The inner member 3 is prevented from coming loose with a nut 9, and a wheel mounting bolt 10 is inserted into the hub 6.

[0020] As shown in Figure 2, tapered double-row outer raceway surfaces 4a, 4a are formed on the inner circumference of the outer member 4, and tapered inner raceway surfaces 3a, 3a are formed on the outer circumferences of the pair of inner members 3, 3, facing these double-row outer raceway surfaces 4a, 4a. Double-row tapered rollers 5, 5 are housed between the two raceway surfaces via cages 11, 11 so that they can roll freely. The front end faces of the pair of inner members 3, 3 are set in abutting relationship, forming a so-called back-to-back type double-row tapered roller bearing. Seals 12, 13 are attached to both ends of the outer member 4 to prevent leakage of the lubricating grease sealed inside the bearing and to prevent rainwater, dust, etc. from entering the bearing from the outside.

[0021] A flange-like large rib 3b that receives thrust loads from the large end faces 5a of each tapered roller 5 is formed integrally with the large diameter end of the tapered inner rolling surface 3a of the inner member 3, and the large end faces 5a of the tapered rollers 5 roll in contact with this large rib 3b.

[0022] Of the seals 12, 13 attached to both ends of the outer member 4, the outer seal 12 is an integrated seal made up of a core 12a press-fitted into the inner periphery of the end of the outer member 4 and a seal member 12b integrally joined to this core 12a by vulcanization adhesion. The core 12a is made of austenitic stainless steel plate (JIS standard SUS304 series, etc.) or cold-rolled steel plate (JIS standard SPCC series, etc.) and is formed by pressing to have a substantially L-shaped cross section.

[0023] The seal member 12b is made of synthetic rubber such as NBR (acrylonitrile butadiene rubber). In addition to the exemplified NBR, other materials that can be used for the seal member 12b include HNBR (hydrogenated acrylonitrile butadiene rubber) and EPDM (ethylene propylene rubber), which have excellent heat resistance, as well as ACM (polyacrylic rubber), FKM (fluororubber), and silicone rubber, which have excellent heat and chemical resistance.

[0024] On the other hand, as shown enlarged in Figure 3, the inner seal 13 constitutes a so-called pack seal, consisting of an annular seal plate 14 and a slinger 15, which are arranged facing each other and have a substantially L-shaped cross section. The seal plate 14 is made up of a core metal 16 press-fitted into the outer member 4, and a seal member 17 integrally bonded to the core metal 16 by vulcanization.

[0025] The core metal 16 is formed by pressing an austenitic stainless steel plate or a cold-rolled steel plate to have a substantially L-shaped cross section, and is provided with a cylindrical fitting portion 16a that is press-fitted onto the inner periphery of the end of the outer member 4, and an inner diameter portion 16b that extends radially inward from one end of the fitting portion 16a. The tip of the fitting portion 16a of the core metal 16 is formed thin-walled, and a seal member 17 is joined around and wraps around this tip so as to cover it.

[0026] The seal member 17 is made of synthetic rubber such as NBR and includes a base 17a that covers the inner circumferential surface of the fitting portion 16a of the core 16, a pair of side lips 17b, 17c that are inclined radially outward from the base 17a, and a grease lip 17d and a dust lip 17e that are bifurcated on the inner diameter side of the side lip 17c. A garter spring 17f made of austenitic stainless steel or other stainless steel is attached to the dust lip 17e. This ensures high corrosion resistance over a long period of time. In addition to the NBR mentioned above, other examples of the material for the seal member 17 include heat-resistant materials such as HNBR, EPDM, ACM, FKM, and silicone rubber.

[0027] The slinger 15 is made of a ferromagnetic steel plate, for example, a ferritic stainless steel plate (JIS standard The cross section is roughly L-shaped and is press-formed from cold-rolled steel plate that has been treated with rust prevention, such as SUS430. The seal member 17 is formed in a cylindrical portion 15a that is press-fitted onto the outer diameter of the inner member 3, and comprises a standing portion 15b that extends radially outward from the cylindrical portion 15a. Side lips 17b, 17c of the seal member 17 are in sliding contact with the standing portion 13b via a predetermined axial interference, and a grease lip 17d and a dust lip 17e are in sliding contact with the cylindrical portion 15a via a predetermined radial interference.

[0028] Furthermore, the base 17a of the seal member 17 is formed at an angle toward the tip of the fitting portion 16a of the core metal 16, and the open end of the seal member 17 and the outer edge of the upright portion 15b of the slinger 15 face each other with a small radial gap between them, forming a labyrinth seal 19. This prevents rainwater, dust, etc. from entering the bearing from the outside, and allows rainwater, dust, etc. that has entered to be easily discharged to the outside by centrifugal force without remaining inside the seal 13, improving sealing performance.

[0029] Furthermore, a seal plate 15c that seals the gap between the cylindrical portion 15a of the slinger 15 and the inner member 3 is integrally bonded to the inner side surface of the upright portion 15b of the slinger 15 by vulcanization adhesion.

[0030] Next, a metal pulser ring 21 is attached to the inner end of the outer member 4, which is the rotating member, and a rotation sensor 22 is arranged opposite the pulser ring 21. The pulser ring 21 consists of a cylindrical portion 21a that is press-fitted onto the outer diameter of the end of the outer member 4, which is the rotating member, and a standing portion 21b that extends from this cylindrical portion 21a toward the outer diameter surface of the inner member 3, which is the fixed member, and the standing portion 21b is inclined inward toward the end. Openings 21c that serve as detection targets for the rotation sensor 22 are provided at equal intervals around the circumferential direction in the standing portion 21b of the pulser ring 21. The rotation of the pulser ring 21 that accompanies the rotation of the bearing is detected by the rotation sensor 22, thereby fulfilling the function of an ABS sensor.

[0031] In this way, by uniting the pulsar ring 21 with the bearing, the process of attaching the pulsar ring 21 is not required during vehicle assembly. Also, by using the end face of the outer member 4 of the bearing as the reference surface for aligning the pulsar ring 21, alignment can be easily performed without additional processing of the attachment part. In vehicles used in harsh environments such as trucks, magnetic encoders made of resin may deteriorate due to peripheral oils and greases such as brake fluid, but by making the pulsar ring 21 out of metal, durability can be ensured.

[0032] The pulsar ring 21 is made of a shape memory alloy. When the temperature of the bearing rises, the temperature of the pulsar ring 21, which is made of a shape memory alloy, also rises. When the temperature exceeds the shape recovery temperature of the shape memory alloy, for example, as shown in Fig. 3, the upright portion 21b, which slopes inward toward the end, deforms toward the outer side as shown in Fig. 4, and the distance between the end face of the pulsar ring 21 and the rotation sensor 22 changes. The temperature of the bearing can be estimated from the change in output of the rotation sensor 22 that accompanies this change in distance, and an abnormal rise in the temperature of the bearing can be detected, thereby detecting a bearing failure.

[0033] Here, the material used for the shape memory alloy is usually Ni-Ti (nickel-titanium) alloy, but in order to detect even higher temperatures (130 to 150°C), an Fe-Mn-Al-Ni alloy or the like is used.

[0034] A seal lip 23 having an interference fit with the outer diameter of the inner member 3, which is the fixed member, is provided at the tip of the upright portion 21b of the pulsar ring 21, preventing muddy water and the like from entering the inside of the bearing.

[0035] By providing a seal lip 23 at the tip of the upright portion 21b of the pulsar ring 21, the sealing performance of the bearing is improved, and therefore the number of lips in the sealing parts can be reduced, simplifying the sealing structure and reducing costs.

[0036] As shown in Fig. 5, openings 21c are formed in the upright portion 21b of the pulsar ring 21 at equal intervals in the circumferential direction, and these openings 21c are blocked by rubber material 24 that is integral with the seal lip 23. Blocking the openings 21c of the pulsar ring 21 with the rubber material 24 can improve the sealing performance of the bearing. The seal lip 23 and the rubber material 24 are formed of non-magnetic rubber, and the rubber material 24 that blocks the openings 21c is located on the side of the pulsar ring 21 that faces the bearing. By providing the rubber material 24 on the surface opposite to the rotation sensor 22 side, it is possible to provide sealing performance without impairing the function of the pulsar ring 21.

[0037] Figure 4 shows the shape of the pulsar ring 21 after it has been deformed from the shape shown in Figure 3. If the shape change of the pulsar ring 21 is set in the direction of increasing the interference of the seal lip 23, as shown in Figures 3 and 4, when a shape change occurs due to a rise in temperature, the amount of heat generated by the seal lip 23 increases, causing the temperature to rise. By applying positive feedback to the temperature rise, it is possible to detect the temperature rise more sensitively. Conversely, by setting the interference to be smaller, it is possible to lower the detection sensitivity.

[0038] In the above embodiment, the garter spring 17f is attached to the dust lip 17e, but in this invention, the sealing performance of the bearing is improved by providing a seal lip 23 at the tip of the upright portion 21b of the pulsar ring 21, so the garter spring 17f can be omitted as shown in Figure 6. By omitting the garter spring 17f, torque can be reduced.

[0039] Although the above embodiment has been described as a wheel bearing device with an outer ring rotating, the same effect can be obtained even in a wheel bearing device with an inner ring rotating by fixing the pulser ring 21 to the inner ring, which is the rotating side member.

[0040] The present invention is not limited to the above-described embodiments, and can of course 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. [Explanation of symbols]

[0041] 3: Inner member 3a: Inner rolling surface 4: Outer member 4a: Outside raceway 5: Tapered roller 11:Retainer 12, 13: Stickers 21: Pulsar Ring 21a: Cylindrical part 21b: Standing board section 21c: opening 22: Rotation sensor 23: Seal lip 24: Rubber material

Claims

1. A wheel bearing device comprising an outer member having double-row outer raceway surfaces integrally formed on its inner periphery, an inner member having double-row inner raceway surfaces formed on its outer periphery opposite the double-row outer raceway surfaces, double-row rolling elements housed between the raceway surfaces of the inner member and the outer member via a cage so as to be able to roll freely, and a seal attached to an opening of an annular space formed between the outer member and the inner member, the wheel bearing device comprising a pulser ring attached to the rotating member of the outer member or the inner member, and a rotation sensor arranged opposite to a detected portion of the pulser ring, the pulser ring having a cylindrical portion fitted to an end of the rotating member, a vertical plate portion extending from the cylindrical portion toward the fixed member and having a detection portion in the circumferential direction, and a seal lip having an interference fit with the fixed member is provided at the tip of the vertical plate portion, and of the cylindrical portion and vertical plate portion that make up the pulsar ring, at least the vertical plate portion is formed from a shape memory alloy, and the shape memory alloy is an Fe-Mn-Al-Ni alloy that deforms at 130 to 150°C, and when the shape recovery temperature of the vertical plate portion is exceeded, the vertical plate portion deforms in a direction that changes the distance from the rotation sensor, and an abnormal temperature rise in the bearing is detected based on a change in the output of the rotation sensor due to this deformation.

2. 2. A wheel bearing device according to claim 1, wherein the direction of deformation of the upright portion of the pulsar ring is set so that the interference of the seal lip provided at the tip of the upright portion with the fixed member is increased.

3. 3. A wheel bearing device according to claim 1, wherein the detection portion of the pulser ring consists of openings provided at equal intervals in the circumferential direction in the upright portion, and a non-magnetic rubber material that covers the openings is provided on the side of the upright portion opposite the position of the rotation sensor.

4. 4. A wheel bearing device according to claim 3, wherein the non-magnetic rubber material that closes the opening is formed integrally with a seal lip at the tip of the upright portion.

5. 5. A wheel bearing device according to claim 1, wherein the rolling elements are tapered rollers.

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