Bearing device for wheel

Abstract

The purpose of the present invention is to suppress increases in the torque of a sealing device with respect to a hub ring. In a bearing device 1 for a wheel, the volume Vp1a of a space surrounded by a side lip 92d, an intermediate lip 92c, and a sliding contact surface 34 and the volume Vp1b of a space surrounded by the intermediate lip 92c, a grease lip 92b, and the sliding contact surface 34 when the axial position of an outer side seal member 9 with respect to a hub ring 3 is a first intermediate position and the volume VS1a of a space surrounded by the side lip 92d, the intermediate lip 92c, and the sliding contact surface 34 and the volume VS1b of a space surrounded by the intermediate lip 92c, the grease lip 92b, and the sliding contact surface 34 when the axial position of the outer side seal member 9 with respect to the hub ring 3 is a first use position satisfy the relationship 0.1 ≤ (VP1a-VS1a) / Vp1a+(Vp1b-VS1b) / Vp1b ≤ 0.6.

Description

Wheel bearing device

[0001] The present invention relates to a wheel bearing device.

[0002] Conventionally, a wheel bearing device that rotatably supports a wheel in a suspension device of a vehicle such as an automobile is known. In the wheel bearing device, a double row of rolling elements are rotatably accommodated between the outer raceway surface of the outer member and the inner raceway surface of the inner member. Further, the wheel bearing device is provided with a sealing device that closes the open end of the annular space formed by the outer member and the inner member to prevent foreign matter such as mud and water from entering.

[0003] For example, the wheel bearing device described in Patent Document 1 includes an outer ring that is an outer member having a double row of outer raceway surfaces, a hub ring having a wheel mounting flange on the outer side, and an inner ring press-fitted to the inner end portion of the hub ring. It consists of an inner member having a double row of inner raceway surfaces facing the double row of outer raceway surfaces, a double row of rolling elements rotatably accommodated between both raceway surfaces of the outer member and the inner member, and an outer side of the annular space formed by the outer member and the inner member. And an outer side sealing device that closes the open end.

[0004] The outer side sealing device is composed of a three-lip seal having a grease lip located on the innermost diameter side, a side lip located on the outermost diameter side, and an intermediate lip located between the grease lip and the side lip. Each seal lip is in contact with a sliding contact surface located at the base end portion of the wheel mounting flange in the hub ring.

[0005] Japanese Patent Application Laid-Open No. 2013-217428

[0006] In the wheel bearing device as described above, when the outer ring is incorporated into the hub ring from the inner side toward the outer side, among the plurality of seal lips in the outer side sealing device press-fitted to the outer ring, the grease lip first contacts the sliding contact surface of the hub ring, and then the side lip and the intermediate lip contact the sliding contact surface of the hub ring. After the side lip and the intermediate lip contact the sliding contact surface, the outer ring moves toward the outer side to the normal assembly position, and the side lip and the intermediate lip are pushed into the sliding contact surface.

[0007] When each seal lip of the sealing device comes into contact with the hub ring, a sealed space is formed between the grease lip and the intermediate lip and the hub ring, and another sealed space is formed between the side lip and the intermediate lip and the hub ring. However, once each seal lip is pressed against the sliding surface after the sealed space has been formed, each seal lip deforms, reducing the volume of the sealed space and allowing air to escape from the sealed space.

[0008] A seal lip that has been pressed into the sliding surface and deformed will try to return to its original shape after air escapes from the sealed space, creating negative pressure within the sealed space. When negative pressure is generated within the sealed space, the torque on the hub wheel of the sealing device increases compared to before the negative pressure was generated.

[0009] The present invention has been made in view of the above circumstances, and provides a wheel bearing device that can suppress the increase in torque of the sealing device on the hub wheel when the outer member to which the sealing device is fitted is assembled to the hub wheel.

[0010] In other words, the wheel bearing device consists of an outer member having double rows of outer raceway surfaces on its inner circumference, a hub ring having a wheel mounting flange on one axial side for attaching a wheel and a small diameter stepped portion extending axially on its outer circumference, and at least one inner ring press-fitted into the small diameter stepped portion of the hub ring, an inner member having double rows of inner raceway surfaces facing the double rows of outer raceway surfaces, double rows of rolling elements rotatably housed between the two raceway surfaces of the outer member and the inner member, and an annular ring fitted to the outer member and formed by the outer member and the inner member. A wheel bearing device comprising a sealing device that closes an open end on one axial side of a space, wherein the sealing device comprises a core metal fitted to one axial side of the outer member, and an elastic member joined to the core metal and having a plurality of seal lips extending toward the hub ring, the hub ring having a sliding contact surface at the base end of the wheel mounting flange in contact with the seal lips of the elastic member, the seal lip having a grease lip located on the innermost diameter side, a side lip located on the outermost diameter side, and the relationship between the grease lip and the side lip The sealing device has an intermediate lip located between it, and when the axial position of the sealing device with respect to the hub wheel is at a first intermediate position in which the grease lip, the intermediate lip, and the side lip are in contact with the sliding surface and the side lip is in a natural state not deformed by external force, the volume VP1a of the space enclosed by the side lip and the intermediate lip and the sliding surface, and the volume VP1b of the space enclosed by the intermediate lip and the grease lip and the sliding surface, and the axial position of the sealing device with respect to the hub wheel is, When the grease lip, the intermediate lip, and the side lip are in contact with the sliding surface and the side lip and the intermediate lip are deformed by being pressed against the sliding surface, the volume VS1a of the space enclosed by the side lip and the intermediate lip and the sliding surface, and the volume VS1b of the space enclosed by the intermediate lip and the grease lip and the sliding surface, have the relationship 0.1 ≤ (VP1a - VS1a) / VP1a + (VP1b - VS1b) / VP1b ≤ 0.6.

[0011] Furthermore, the wheel bearing device comprises an outer member having double rows of outer raceway surfaces on its inner circumference, a hub ring having a wheel mounting flange on one axial side for mounting a wheel and a small diameter stepped portion extending axially on its outer circumference, and at least one inner ring press-fitted into the small diameter stepped portion of the hub ring, an inner member having double rows of inner raceway surfaces facing the double rows of outer raceway surfaces, double rows of rolling elements rotatably housed between the raceway surfaces of the outer member and the inner member, and a tight seal fitted to the outer member that closes the axial opening end on one side of the annular space formed by the outer member and the inner member. A wheel bearing device comprising a sealing device, wherein the sealing device comprises a core metal fitted to one axial side of the outer member, and an elastic member joined to the core metal and having a plurality of seal lips extending toward the hub ring, the hub ring having a sliding contact surface at the base end of the wheel mounting flange in contact with the seal lips of the elastic member, the seal lips having a grease lip located on the innermost diameter side, a side lip located on the outermost diameter side, and an intermediate lip located between the grease lip and the side lip, and the axial direction of the sealing device toward the hub ring When the position is at a second intermediate position in which the grease lip and the side lip are in contact with the sliding surface, the intermediate lip is not in contact with the sliding surface, and the side lip is in a natural state where it is not deformed by external force, the volume VP2 of the space enclosed by the grease lip and the side lip and the sliding surface, and when the axial position of the sealing device with respect to the hub wheel is at a third intermediate position in which the grease lip, the intermediate lip and the side lip are in contact with the sliding surface, and the intermediate lip is in a natural state where it is not deformed by external force, The volume VP3a of the space enclosed by the side lip, the intermediate lip and the sliding surface, the volume VP3b of the space enclosed by the intermediate lip, the grease lip and the sliding surface, and the volume VS1c of the space enclosed by the side lip, the intermediate lip and the sliding surface when the axial position of the sealing device with respect to the hub wheel is in the first operating position in which the grease lip, the intermediate lip and the side lip are in contact with the sliding surface and the side lip and the intermediate lip are deformed by being pressed against the sliding surface.Furthermore, the volume VS1d of the space enclosed by the intermediate lip, the grease lip, and the sliding surface has the relationship 0.1 ≤ (VP2 - (VP3a + VP3b)) / VP2 + (VP3a - VS1c) / VP3a + (VP3b - VS1d) / VP3b ≤ 0.6.

[0012] Furthermore, the wheel bearing device comprises an outer member having double rows of outer raceway surfaces on its inner circumference, a hub ring having a wheel mounting flange on one axial side for mounting a wheel and a small diameter stepped portion extending axially on its outer circumference, and at least one inner ring press-fitted into the small diameter stepped portion of the hub ring, an inner member having double rows of inner raceway surfaces facing the double rows of outer raceway surfaces, double rows of rolling elements rotatably housed between the two raceway surfaces of the outer member and the inner member, and a sealing device fitted to the outer member and closing the axial opening end on one side of the annular space formed by the outer member and the inner member, wherein the sealing device comprises a core metal fitted to one axial side of the outer member, and an elastic member joined to the core metal and having a plurality of seal lips extending toward the hub ring, the hub ring having a sliding contact surface at the base end of the wheel mounting flange in contact with the seal lips of the elastic member, and the seal lips are located in the innermost green The sealing device has a slip, a side lip located on the outermost diameter side, and an intermediate lip located between the grease slip and the side lip, and the volume VP4 of the space enclosed by the side lip, the grease slip and the grease slip and the sliding surface when the axial position of the sealing device with respect to the hub wheel is a fourth intermediate position in which the grease slip and the side lip are in contact with the sliding surface, the intermediate lip is not in contact with the sliding surface, and the side lip is in a natural state not deformed by external force, and the volume VS2 of the space enclosed by the side lip, the grease slip and the sliding surface when the axial position of the sealing device with respect to the hub wheel is a second operating position in which the grease slip and the side lip are in contact with the sliding surface, the intermediate lip is not in contact with the sliding surface, and the side lip is deformed by being pressed against the sliding surface, the relationship between 0.1 ≤ (VP4 - VS2) / VP4 ≤ 0.6.

[0013] Furthermore, the wheel bearing device comprises an outer member having double rows of outer raceway surfaces on its inner circumference, a hub ring having a wheel mounting flange on one axial side for mounting a wheel and a small diameter stepped portion extending axially on its outer circumference, and at least one inner ring press-fitted into the small diameter stepped portion of the hub ring, an inner member having double rows of inner raceway surfaces facing the double rows of outer raceway surfaces, double rows of rolling elements rotatably housed between the two raceway surfaces of the outer member and the inner member, and a sealing device fitted to the outer member and closing the axial opening end on one side of the annular space formed by the outer member and the inner member, wherein the sealing device comprises a core metal fitted to one axial side of the outer member, and an elastic member joined to the core metal and having a plurality of seal lips extending toward the hub ring, and the hub ring has the base end of the wheel mounting flange, the seal of the elastic member The sealing device has a sliding surface with which the seal lip makes contact, and the seal lip has a grease lip located on the innermost diameter side and a side lip located on the outermost diameter side, and the volume VP5 of the space enclosed by the side lip and the grease lip and the sliding surface when the axial position of the sealing device with respect to the hub wheel is a fifth intermediate position in which the grease lip and the side lip are in contact with the sliding surface and the side lip is in a natural state not deformed by external force, and the volume VS3 of the space enclosed by the side lip and the grease lip and the sliding surface when the axial position of the sealing device with respect to the hub wheel is a third operating position in which the grease lip and the side lip are in contact with the sliding surface and the side lip is deformed by being pressed against the sliding surface, the relationship between 0.1 ≤ (VP5 - VS3) / VP5 ≤ 0.6.

[0014] Furthermore, the wheel bearing device comprises an outer member having double rows of outer raceway surfaces on its inner circumference, a hub ring having a wheel mounting flange on one axial side for mounting a wheel and a small-diameter stepped portion extending axially on its outer circumference, and at least one inner ring press-fitted into the small-diameter stepped portion of the hub ring, an inner member having double rows of inner raceway surfaces facing the double rows of outer raceway surfaces, double rows of rolling elements rotatably housed between the raceway surfaces of the outer member and the inner member, and a seal fitted to the outer member that closes the axial opening end on one side of the annular space formed by the outer member and the inner member. A wheel bearing device comprising a device and a sealing device, wherein the sealing device comprises a core metal fitted to one axial side of the outer member, and an elastic member joined to the core metal and having a plurality of seal lips extending toward the hub ring, the hub ring having a sliding contact surface at the base end of the wheel mounting flange in contact with the seal lips of the elastic member, the seal lip having a grease lip located on the innermost diameter side, a side lip located on the outermost diameter side, and an intermediate lip located between the grease lip and the side lip, and the axial position of the sealing device toward the hub ring When the position is in a sixth intermediate position in which the grease lip and the intermediate lip are in contact with the sliding surface, the side lip is not in contact with the sliding surface, and the intermediate lip is in a natural state where it is not deformed by external force, the volume VP6b of the space enclosed by the grease lip and the intermediate lip and the sliding surface, and when the axial position of the sealing device with respect to the hub wheel is in a seventh intermediate position in which the grease lip, the intermediate lip, and the side lip are in contact with the sliding surface, and the side lip is in a natural state where it is not deformed by external force, The volume VP7a of the space enclosed by the intermediate lip and the side lip and the sliding surface, and the volume VS1e of the space enclosed by the side lip and the intermediate lip and the sliding surface, and the volume VS1f of the space enclosed by the intermediate lip and the grease lip and the sliding surface, when the axial position of the sealing device with respect to the hub wheel is in the first operating position, in which the grease lip, the intermediate lip and the side lip are in contact with the sliding surface and the side lip and the intermediate lip are deformed by being pressed against the sliding surface,The relationship 0.1 ≤ (VP6b - VS1f) / VP6b + (VP7a - VS1e) / VP7a ≤ 0.6 holds true.

[0015] According to the present invention, it is possible to suppress the increase in torque applied to the hub wheel by a sealing device assembled in a wheel bearing device.

[0016] This is a side cross-sectional view showing a wheel bearing device. This is a side cross-sectional view showing the outer side seal member. This is a side cross-sectional view showing how the grease slip first contacts the sliding surface of the hub ring when the outer ring incorporated into the hub ring moves toward the outer side. Figure 4A is a side cross-sectional view showing the outer side seal member in the first intermediate position, and Figure 4B is a side cross-sectional view showing the outer side seal member in the first use position. This is a diagram showing the relationship between negative pressure parameters and torque. This is a side cross-sectional view showing the connection surface at a sliding surface with a radius of curvature set to 4.0 mm or less. This is a side cross-sectional view showing the outer side seal member according to the second embodiment. This is a side cross-sectional view showing the outer side seal member according to the third embodiment. This is a side cross-sectional view showing the outer side seal member according to the fourth embodiment, where Figure 9A is a side cross-sectional view showing the outer side seal member in the second intermediate position, and Figure 9B is a side cross-sectional view showing the outer side seal member in the third intermediate position. This is a side cross-sectional view showing the outer side seal member according to the fourth embodiment, where the outer side seal member is in the first use position. Figure 11A is a side cross-sectional view showing the outer seal member in the fourth intermediate position, and Figure 11B is a side cross-sectional view showing the outer seal member in the second usage position. Figure 12A is a side cross-sectional view showing the outer seal member in the fifth intermediate position, and Figure 12B is a side cross-sectional view showing the outer seal member in the third usage position. Figure 13A is a side cross-sectional view showing the outer seal member in the seventh embodiment, where the grease slip first contacts the sliding surface of the hub ring when the outer ring incorporated into the hub ring moves toward the outer side, and Figure 13B is a side cross-sectional view showing the outer seal member in the sixth intermediate position. Figure 14A is a side cross-sectional view showing the outer seal member in the seventh embodiment, where the grease slip first contacts the sliding surface of the hub ring when the outer ring incorporated into the hub ring moves toward the outer side, and Figure 13B is a side cross-sectional view showing the outer seal member in the sixth intermediate position.

[0017] The embodiments for carrying out the present invention will be described below with reference to the attached drawings.

[0018] [Wheel Bearing Device] The wheel bearing device 1 shown in Figure 1 is an embodiment of the wheel bearing device according to the present invention, and is used to rotatably support a wheel in the suspension system of a vehicle such as an automobile. The wheel bearing device 1 is configured as a wheel bearing device for a drive wheel.

[0019] In the following description, "axial direction" refers to the direction along the rotation axis X of the wheel bearing device 1, "radial direction" refers to the direction perpendicular to the rotation axis X of the wheel bearing device 1, and "circumferential direction" refers to the direction along the arc centered on the rotation axis X of the wheel bearing device 1. Furthermore, "outer side" refers to one side in the axial direction, which is the wheel side of the wheel bearing device 1 when mounted on the vehicle body, and "inner side" refers to the other side in the axial direction, which is the vehicle body side of the wheel bearing device 1 when mounted on the vehicle body.

[0020] The wheel bearing device 1 has a configuration referred to as the third generation, and comprises an outer ring 2 which is an outer member, a hub ring 3 and an inner ring 4 which are inner members, two rows of inner ball rows 5 and outer ball rows 6 which are rolling rows, an outer sealing member 9 and an inner sealing member 10.

[0021] An inner side opening 21 into which an inner side sealing member 10 can be fitted is formed at the inner side end of the outer ring 2. An outer side opening 22 into which an outer side sealing member 9 can be fitted is formed at the outer side end of the outer ring 2.

[0022] The inner side seal member 10 is fitted into the inner side opening 21, thereby closing the inner side opening end of the annular space S formed by the outer ring 2 (an outer member) and the hub ring 3 and inner ring 4 (inner members). The outer side seal member 9 is fitted into the outer side opening 22, thereby closing the outer side opening end of the annular space S.

[0023] The inner sealing member 10 and the outer sealing member 9 are sealing devices that close the open end of the annular space S. By closing the inner and outer open ends of the annular space S with the inner sealing member 10 and the outer sealing member 9 in this way, foreign matter such as muddy water is prevented from entering the inside of the wheel bearing device 1.

[0024] The inner circumferential surface of the outer ring 2 has an inner outer raceway surface 23 and an outer outer raceway surface 24. A vehicle body mounting flange 25 for attaching the outer ring 2 to the vehicle body side member is integrally formed on the outer circumferential surface of the outer ring 2. The vehicle body mounting flange 25 is provided with bolt holes 26 into which fastening members (in this case, bolts) for fastening the vehicle body side member and the outer ring 2 are inserted.

[0025] A small-diameter stepped portion 31, which is smaller in diameter than the outer end, is formed on the inner end of the outer surface of the hub wheel 3. A wheel mounting flange 32 for attaching a wheel is integrally formed on the outer end of the hub wheel 3.

[0026] Multiple bolt holes 35 are formed in the wheel mounting flange 32. Hub bolts 36 for fastening the hub wheel 3 to the wheel or brake components can be press-fitted into the bolt holes 35. The bolt holes 35 can also be configured to accommodate screwed wheel bolts.

[0027] In the hub wheel 3, a sliding contact surface 34 is formed at the base end of the wheel mounting flange 32, into which the outer side sealing member 9 slides. On the outer circumferential surface of the hub wheel 3, an outer side inner raceway surface 33 is provided, facing the outer side outer raceway surface 24 of the outer ring 2. In other words, the inner raceway surface 33 is formed on the outer side of the inner member by the hub wheel 3.

[0028] An axle hole 37 is formed in the inner diameter portion of the hub wheel 3, extending along the axial direction. The axle hole 37 penetrates the hub wheel 3 along the axial direction, and the shaft portion of a constant velocity universal joint can be connected to the axle hole 37.

[0029] An inner ring 4 is provided on the small-diameter stepped portion 31 of the hub ring 3. The inner ring 4 is fixed to the small-diameter stepped portion 31 of the hub ring 3 by press-fitting. An inner raceway surface 41 is provided on the outer circumferential surface of the inner ring 4 so as to face the outer raceway surface 23 on the inner side of the outer ring 2. In other words, the inner raceway surface 41 is formed on the inner side of the inner member by the inner ring 4.

[0030] The inner ball row 5 and the outer ball row 6, which are rolling elements, are composed of multiple balls 7, which are rolling elements, held by a retainer 8. The inner ball row 5 is rotatably sandwiched between the inner raceway surface 41 of the inner ring 4 and the inner outer raceway surface 23 of the outer ring 2. The outer ball row 6 is rotatably sandwiched between the inner raceway surface 33 of the hub ring 3 and the outer outer raceway surface 24 of the outer ring 2. In other words, the inner ball row 5 and the outer ball row 6 are rotatably housed between the raceway surfaces of the outer and inner members.

[0031] In the wheel bearing device 1, a double-row angular contact ball bearing is constructed from an outer ring 2, a hub ring 3 and an inner ring 4, an inner ball row 5, and an outer ball row 6. Alternatively, the wheel bearing device 1 may be configured with a double-row tapered roller bearing instead of the double-row angular contact ball bearing.

[0032] [Outer sealing member] The outer sealing member 9 is an example of a sealing device that closes the axial opening end of the annular space formed by the outer member and the inner member.

[0033] As shown in Figure 2, the outer sealing member 9 has a core metal 91 and an elastic member 92. The core metal 91 is made of, for example, a steel plate and is cylindrical in shape, and is fitted to the outer opening 22 of the outer ring 2.

[0034] The elastic member 92 is made of, for example, synthetic rubber and is bonded to the core metal 91 by vulcanization adhesive. The elastic member 92 has a base portion 92a that is vulcanized and bonded to the core metal 91, and a grease lip 92b, an intermediate lip 92c, and a side lip 92d that extend from the base portion 92a toward the hub wheel 3 and are each formed in an annular shape. The grease lip 92b, the intermediate lip 92c, and the side lip 92d are sealing lips of the elastic member 92. The outer side sealing member 9 is a three-lip seal having three sealing lips.

[0035] The grease lip 92b is positioned on the innermost side among the multiple seal lips of the elastic member 22, and extends from the base 92a toward the inner diameter and inner side. The side lip 92d is positioned on the outermost side among the multiple seal lips of the elastic member 22, and extends from the base 92a toward the outer diameter and outer side.

[0036] The intermediate lip 92c is positioned radially between the grease lip 92b and the side lip 92d, and extends from the base 92a toward the outer diameter and outer side. The intermediate lip 92c is located toward the outer diameter side of the grease lip 92b and toward the inner diameter side of the side lip 92d.

[0037] The grease lip 92b, intermediate lip 92c, and side lip 92d of the elastic member 92 are in slidable contact with the sliding contact surface 34 of the hub wheel 3. In other words, the seal lip of the elastic member 92 is in sliding contact with the sliding contact surface 34.

[0038] The sliding contact surface 34 has an axial surface 34a which is aligned along the axial direction, a radial surface 34b which is aligned along the radial direction perpendicular to the axial direction, and a connecting surface 34c which connects the axial surface 34a and the radial surface 34b. The connecting surface 34c is an arc-shaped surface formed in a circular arc shape that is convex on the outer side and on the inner diameter side.

[0039] The grease lip 92b is in contact with the axial surface 34a of the sliding surface 34 at the first contact point P1. The side lip 92d is in contact with the radial surface 34b of the sliding surface 34 at the second contact point P2. The intermediate lip 92c is in contact with the connecting surface 34c of the sliding surface 34 at the third contact point P3. The connecting surface 34c is located between the first contact point P1 and the second contact point P2.

[0040] In the outer sealing member 9 that slides against the sliding surface 34 of the hub wheel 3, a sealed space C is formed, surrounded by multiple sealing lips of the elastic member 22 and the sliding surface 34 of the hub wheel 3.

[0041] The space C is formed in a range surrounded by the side lip 92d, the grease lip 92b, and the sliding contact surface 34, and is divided into a first space Ca and a second space Cb by the intermediate lip 92c. The first space Ca is a space surrounded by the side lip 92d, the intermediate lip 92c, and the sliding contact surface 34. The second space Cb is a space surrounded by the intermediate lip 92c, the grease lip 92b, and the sliding contact surface 34.

[0042] [Negative pressure parameters of the outer side seal member] In the wheel bearing device 1, when the outer ring 2 is incorporated into the hub ring 3 from the inner side toward the outer side, the outer ring 2 in a state where the outer side seal member 9 is fitted into the outer side opening 22 is incorporated into the hub ring 3.

[0043] As shown in FIG. 3, when the outer ring 2 incorporated into the hub ring 3 moves toward the outer side, among the plurality of seal lips of the outer side seal member 9, the grease lip 92b first contacts the sliding contact surface 34 of the hub ring 3. In this case, the grease lip 92b contacts the axial direction surface 34a of the sliding contact surface 34. The grease lip 92b that has contacted the sliding contact surface 34 of the hub ring 3 is deformed to the outer diameter side with respect to the grease lip 92b in a natural state where no external force is acting.

[0044] As shown in FIG. 4A, after the grease lip 92b contacts the hub ring 3, when the outer ring 2 further moves toward the outer side, the side lip 92d and the intermediate lip 92c contact the sliding contact surface 34 of the hub ring 3. In this case, the side lip 92d contacts the radial direction surface 34b of the sliding contact surface 34, and the intermediate lip 92c contacts the connection surface 34c of the sliding contact surface 34. When the side lip 92d and the intermediate lip 92c contact the sliding contact surface 34 of the hub ring 3, a space C, which is a sealed space surrounded by the plurality of seal lips of the elastic member 22 and the sliding contact surface 34 of the hub ring 3, is formed.

[0045] As shown in FIG. 4A, when the side lip 92d and the intermediate lip 92c contact the sliding contact surface 34, the side lip 92d and the intermediate lip 92c are in a natural state where they are not deformed by an external force.

[0046] In FIG. 4A, the axial position of the outer seal member 9 with respect to the hub ring 3 is the first intermediate position where the side lip 92d, the intermediate lip 92c, and the grease lip 92b are in sliding contact with the sliding surface 34 and the side lip 92d is in a natural state without being deformed by an external force. When the axial position of the outer seal member 9 with respect to the hub ring 3 is at the first intermediate position, the side lip 92d, which is the seal lip on the outermost diameter side, is in a natural state without being deformed by an external force.

[0047] When the outer seal member 9 is at the first intermediate position, the space C surrounded by the side lip 92d and the grease lip 92b of the elastic member 22 and the sliding surface 34 of the hub ring 3 is divided into a first space Ca surrounded by the side lip 92d and the intermediate lip 92c and the sliding surface 34, and a second space Cb surrounded by the intermediate lip 92c and the grease lip 92b and the sliding surface 34.

[0048] The volume of the first space Ca surrounded by the side lip 92d and the intermediate lip 92c and the sliding surface 34 when the outer seal member 9 is at the first intermediate position is VP1a, and the volume of the second space Cb surrounded by the intermediate lip 92c and the grease lip 92b and the sliding surface 34 when the outer seal member 9 is at the first intermediate position is VP1b.

[0049] As shown in FIG. 4B, after the side lip 92d and the intermediate lip 92c of the outer ring 2 come into sliding contact with the sliding surface 34, the outer ring 2 moves outward toward the normal assembly position, and the side lip 92d and the intermediate lip 92c are pushed toward the sliding surface 34. When the side lip 92d and the intermediate lip 92c are pushed toward the sliding surface 34, they are pressed by the sliding surface 34 and deformed with respect to the side lip 92d and the intermediate lip 92c in the natural state.

[0050] In Figure 4B, the axial position of the outer seal member 9 relative to the hub wheel 3 is the first operating position, in which the side lip 92d, intermediate lip 92c, and grease lip 92b are in contact with the sliding surface 34, and the side lip 92d and intermediate lip 92c are deformed by being pressed against the sliding surface 34. When the axial position of the outer seal member 9 relative to the hub wheel 3 is in the first operating position, the side lip 92d, which is the outermost sealing lip, is deformed by being pressed against the sliding surface 34.

[0051] The first usage position of the outer sealing member 9 is the position when the outer ring 2 is assembled to the hub ring 3 to the standard design assembly position, and is the position when the wheel bearing device 1 is mounted on the vehicle body and used.

[0052] When the outer sealing member 9 is in the first operating position, the volume of the first space Ca enclosed by the side lip 92d, the intermediate lip 92c, and the sliding surface 34 is VS1a, and when the outer sealing member 9 is in the first operating position, the volume of the second space Cb enclosed by the intermediate lip 92c, the grease lip 92b, and the sliding surface 34 is VS1b.

[0053] When the outer sealing member 9 moves from the first intermediate position to the first operating position, and the side lip 92d and intermediate lip 92c are pressed against the sliding surface 34 and deformed, the volume of the space C surrounded by the multiple sealing lips of the elastic member 22 and the sliding surface 34 of the hub wheel 3 decreases.

[0054] In other words, the volume VS1a of the first space Ca when the outer side seal member 9 is in the first use position is smaller than the volume VP1a of the first space Ca when the outer side seal member 9 is in the first intermediate position (VP1a > VS1a), and the volume VS1b of the second space Cb when the outer side seal member 9 is in the first use position is smaller than the volume VP1b of the second space Cb when the outer side seal member 9 is in the first intermediate position (VP1b > VS1b).

[0055] When the volumes of the first space Ca and the second space Cb decrease from volumes VP1a and VP1b to volumes VS1a and VS1b, air escapes from the first space Ca and the second space Cb. After the air escapes from the first space Ca and the second space Cb, the multiple seal lips that have deformed in contact with the sliding surface 34 attempt to return to their original shape, generating negative pressure within the first space Ca and the second space Cb. When negative pressure is generated within the first space Ca and the second space Cb, the torque of the outer seal member 9 on the hub wheel 3 increases compared to before the negative pressure was generated within the first space Ca and the second space Cb.

[0056] Therefore, in the wheel bearing device 1, a negative pressure parameter α, which serves as an indicator of the magnitude of negative pressure in the first space Ca and the second space Cb, is defined as shown in the following equation (1), and by setting the negative pressure parameter α within a predetermined range, the increase in torque of the seal member 9 on the hub wheel 3 is suppressed.

[0057] Negative pressure parameter α = (VP1a - VS1a) / VP1a + (VP1b - VS1b) / VP1b ... Equation (1)

[0058] In this embodiment, the negative pressure parameter α is set to satisfy the relationship 0.1 ≤ α ≤ 0.6. When the negative pressure parameter α is set in this way, the volumes VP1a, VP1b and volumes VS1a, VS1b have the relationship 0.1 ≤ (VP1a - VS1a) / VP1a + (VP1b - VS1b) / VP1b ≤ 0.6.

[0059] In this case, in the outer seal member 9, in order to prevent muddy water from entering the inside of the wheel bearing device 1, it is necessary to apply surface pressure to each seal lip of the elastic member 22 that contacts the sliding surface 34, so the minimum value of the negative pressure parameter α is set to 0.1.

[0060] On the other hand, as shown in Figure 5, the larger the value of the negative pressure parameter α, the greater the negative pressure in the first space Ca and the second space Cb. Therefore, by setting the maximum value of the negative pressure parameter α to 0.6, the increase in torque of the sealing member 9 on the hub wheel 3 is suppressed.

[0061] In this way, by setting the value of the negative pressure parameter α to the range of 0.1 ≤ α ≤ 0.6, it is possible to suppress the increase in torque of the outer seal member 9 assembled to the wheel bearing device 1 on the hub wheel 3.

[0062] [Radius of curvature of the sliding contact surface] As shown in Figure 6, in the sliding contact surface 34 of the wheel bearing device 1, the radius of curvature R of the connecting surface 34c, which is an arc-shaped surface, can be set to 4.0 mm or less. In other words, the radius of curvature R of the connecting surface 34c located between the first contact point P1, which the grease lip 92b contacts, and the second contact point P2, which the side lip 92d contacts, can be set to 4.0 mm or less.

[0063] Thus, when the radius of curvature R of the connecting surface 34c is set to a small value such as 4.0 mm or less, it is possible to secure a large volume VP1a of the first space Ca and a large volume VP1b of the second space Cb when the outer side sealing member 9 is in the first intermediate position.

[0064] Therefore, when the volumes of the first space Ca and the second space Cb change from the volumes VP1a and VP1b when the outer side sealing member 9 is in the first intermediate position to the volumes VS1a and VS1b when the outer side sealing member 9 is in the first use position, the rate of decrease in the volumes of the first space Ca and the second space Cb can be reduced.

[0065] This makes it possible to reduce the value of the negative pressure parameter α, thereby suppressing an increase in the torque of the outer seal member 9, which is assembled to the wheel bearing device 1, on the hub wheel 3.

[0066] [Second Embodiment of Outer Seal Member] The outer seal member 9 can also be configured as the outer seal member 9A shown in Figure 7. The outer seal member 9A has a grease lip 92b located on the innermost diameter side, a side lip 92d located on the outermost diameter side, and an intermediate lip 92c located between the grease lip 92b and the side lip 92d. The outer seal member 9A is a three-lip seal having three seal lips.

[0067] The outer sealing member 9A is configured such that, when in the first operating position, the side lip 92d and the intermediate lip 92c contact the radial surface 34b of the sliding surface 34, and the grease lip 92b contacts the axial surface 34a of the sliding surface 34. In this respect, the outer sealing member 9A differs from the outer sealing member 9, in which the side lip 92d contacts the radial surface 34b, the intermediate lip 92c contacts the connecting surface 34c, and the grease lip 92b contacts the axial surface 34a.

[0068] In the outer sealing member 9A, the grease lip 92b is in contact with the axial surface 34a of the sliding surface 34 at the first contact point P1. The side lip 92d is in contact with the radial surface 34b of the sliding surface 34 at the second contact point P2. The intermediate lip 92c is in contact with the radial surface 34b of the sliding surface 34 at the third contact point P3.

[0069] When the intermediate lip 92c is in contact with the connection surface 34c, as in the case of the outer sealing member 9, the deformation of the intermediate lip 92c increases when the outer sealing member 9 moves from the first intermediate position to the first usage position. As a result, the degree of decrease in the volumes VS1a and VS1b relative to the volumes VP1a and VP1b of the first space Ca and the second space Cb increases, and the value of the negative pressure parameter α tends to increase.

[0070] On the other hand, in the outer sealing member 9A, since the side lip 92d and the intermediate lip 92c are in contact with the radial surface 34b, the deformation of the intermediate lip 92c when the outer sealing member 9A moves from the first intermediate position to the first usage position can be kept to a minimum, and the value of the negative pressure parameter α can be reduced.

[0071] [Third Embodiment of Outer Seal Member] The outer seal member 9 can also be configured as the outer seal member 9B shown in Figure 8. The outer seal member 9B has a grease lip 92b located on the innermost diameter side, a side lip 92d located on the outermost diameter side, and an intermediate lip 92c located between the grease lip 92b and the side lip 92d. The outer seal member 9B is a three-lip seal having three seal lips.

[0072] The outer sealing member 9B is configured such that, when in the first use position, the side lip 92d contacts the radial surface 34b of the sliding surface 34, and the grease lip 92b and intermediate lip 92c contact the axial surface 34a of the sliding surface 34. In this respect, the outer sealing member 9B differs from the outer sealing member 9, in which the side lip 92d contacts the radial surface 34b, the intermediate lip 92c contacts the connecting surface 34c, and the grease lip 92b contacts the axial surface 34a.

[0073] In the outer sealing member 9B, the grease lip 92b is in contact with the axial surface 34a of the sliding surface 34 at the first contact point P1. The side lip 92d is in contact with the radial surface 34b of the sliding surface 34 at the second contact point P2. The intermediate lip 92c is in contact with the axial surface 34a of the sliding surface 34 at the third contact point P3.

[0074] When the intermediate lip 92c is in contact with the connection surface 34c, as in the case of the outer sealing member 9, the deformation of the intermediate lip 92c increases when the outer sealing member 9 moves from the first intermediate position to the first usage position. As a result, the degree of decrease in the volumes VS1a and VS1b relative to the volumes VP1a and VP1b of the first space Ca and the second space Cb increases, and the value of the negative pressure parameter α tends to increase.

[0075] On the other hand, in the outer sealing member 9B, since the grease lip 92b and the intermediate lip 92c are in contact with the axial surface 34a, the deformation of the intermediate lip 92c when the outer sealing member 9B moves from the first intermediate position to the first operating position can be kept to a minimum, and the value of the negative pressure parameter α can be reduced.

[0076] [Fourth Embodiment of the Outer Seal Member] The outer seal member 9 can also be configured as the outer seal member 9C shown in Figure 9. The outer seal member 9C has a grease lip 92b located on the innermost diameter side, a side lip 92d located on the outermost diameter side, and an intermediate lip 92c located between the grease lip 92b and the side lip 92d. The outer seal member 9C is a three-lip seal having three seal lips.

[0077] As shown in Figure 9A, in the wheel bearing device 1, when the outer ring 2, with the outer side sealing member 9C fitted into the outer side opening 22, is assembled onto the hub ring 3, as the outer ring 2 moves toward the outer side, the grease lip 92b of the multiple sealing lips of the outer side sealing member 9C first contacts the sliding surface 34 of the hub ring 3, and then the side lip 92d contacts the sliding surface 34.

[0078] In the state shown in Figure 9A, the intermediate lip 92c is in a non-contact state and is not in contact with the sliding surface 34. The grease lip 92b that is in contact with the sliding surface 34 of the hub wheel 3 is deformed outward compared to the grease lip 92b in its natural state when no external force is acting on it. Also, the side lip 92d is in its natural state and is not deformed by external force.

[0079] In Figure 9A, the axial position of the outer sealing member 9C with respect to the hub wheel 3 is a second intermediate position in which the side lip 92d and grease lip 92b are in contact with the sliding surface 34, the intermediate lip 92c is not in contact with the sliding surface 34, and the side lip 92d is in a natural state without deformation due to external force.

[0080] At the second intermediate position, the side lip 92d and grease lip 92b come into contact with the sliding surface 34 of the hub wheel 3, and the intermediate lip 92c does not come into contact with the sliding surface 34, thereby forming a sealed space C surrounded by the side lip 92d and grease lip 92b of the elastic member 22 and the sliding surface 34 of the hub wheel 3.

[0081] In the outer sealing member 9C, the volume of space C when it is in the second intermediate position is VP2. When the outer sealing member 9C is in the second intermediate position, the intermediate lip 92c is not in contact with the sliding surface 34, so the space C surrounded by the side lip 92d, the grease lip 92b, and the sliding surface 34 is formed by a single space.

[0082] As shown in Figure 9B, after the side lip 92d contacts the hub ring 3, as the outer ring 2 moves further outward, the intermediate lip 92c contacts the sliding surface 34 of the hub ring 3. When the intermediate lip 92c contacts the sliding surface 34 of the hub ring 3, the space C is divided into a first space Ca enclosed by the side lip 92d, the intermediate lip 92c and the sliding surface 34, and a second space Cb enclosed by the intermediate lip 92c, the grease lip 92b and the sliding surface 34.

[0083] As shown in Figure 9B, at the point when the intermediate lip 92c contacts the sliding surface 34, the intermediate lip 92c is in a natural state and is not deformed by external forces. In Figure 9B, the axial position of the outer sealing member 9C with respect to the hub wheel 3 is the third intermediate position in which the grease lip 92b, intermediate lip 92c, and side lip 92d are in contact with the sliding surface 34, and the intermediate lip 92c is in a natural state and is not deformed by external forces.

[0084] When the outer sealing member 9C is in the third intermediate position, the volume of the first space Ca enclosed by the side lip 92d, the intermediate lip 92c and the sliding surface 34 is VP3a, and the volume of the second space Cb enclosed by the intermediate lip 92c, the grease lip 92b and the sliding surface 34 is VP3b.

[0085] As shown in Figure 10, after the intermediate lip 92c of the outer ring 2 contacts the sliding surface 34, it moves toward the outer side to the normal assembly position, and the side lip 92d and the intermediate lip 92c are pushed toward the sliding surface 34. When the intermediate lip 92c is pushed toward the sliding surface 34, it is pressed against the sliding surface 34 and becomes deformed compared to the intermediate lip 92c in its natural state. Also, the side lip 92d is pressed against the sliding surface 34 and becomes even more deformed than when the outer side sealing member 9C is in the third intermediate position.

[0086] In Figure 10, the axial position of the outer sealing member 9C with respect to the hub wheel 3 is the first operating position in which the side lip 92d, intermediate lip 92c, and grease lip 92b are in contact with the sliding surface 34, and the side lip 92d and intermediate lip 92c are deformed by being pressed against the sliding surface 34.

[0087] When the outer sealing member 9C is in the first operating position, the volume of the first space Ca enclosed by the side lip 92d, the intermediate lip 92c and the sliding surface 34 is VS1c, and the volume of the second space Cb enclosed by the intermediate lip 92c, the grease lip 92b and the sliding surface 34 is VS1d.

[0088] In a wheel bearing device 1 equipped with an outer side sealing member 9C, the negative pressure parameter α is expressed by the following equation (2).

[0089] Negative pressure parameter α = (VP2 - (VP3a + VP3b)) / VP2 + (VP3a - VS1c) / VP3a + (VP3b - VS1d) / VP3b ...Equation (2)

[0090] In this embodiment as well, the negative pressure parameter α can be set to satisfy the relationship 0.1 ≤ α ≤ 0.6. When the negative pressure parameter α is set in this way, the relationship between volume VP2 and volume VP3a, VP3b and volume VS1c, and VS1d will be 0.1 ≤ (VP2 - (VP3a + VP3b)) / VP2 + (VP3a - VS1c) / VP3a + (VP3b - VS1d) / VP3b ≤ 0.6.

[0091] In this way, by setting the value of the negative pressure parameter α to the range of 0.1 ≤ α ≤ 0.6, it is possible to suppress the increase in torque of the outer sealing member 9C assembled to the wheel bearing device 1 on the hub wheel 3.

[0092] Furthermore, in the outer sealing member 9C, the intermediate lip 92c is not in contact with the sliding surface 34 when the outer sealing member 9C is in the second intermediate position, and is in contact with the sliding surface 34 when the outer sealing member 9C is in the third intermediate position. Therefore, the deformation of the intermediate lip 92c when the outer sealing member 9D moves from the second intermediate position to the first usage position can be reduced, and the value of the negative pressure parameter α can be reduced.

[0093] [Fifth Embodiment of the Outer Seal Member] The outer seal member 9 can also be configured as the outer seal member 9D shown in Figure 11. The outer seal member 9D has a grease lip 92b located on the innermost diameter side, a side lip 92d located on the outermost diameter side, and an intermediate lip 92c located between the grease lip 92b and the side lip 92d. The outer seal member 9D is a three-lip seal having three seal lips.

[0094] As shown in Figure 11A, in the wheel bearing device 1, when the outer ring 2, with the outer side sealing member 9D fitted into the outer side opening 22, is assembled onto the hub ring 3, as the outer ring 2 moves toward the outer side, the grease lip 92b of the multiple sealing lips of the outer side sealing member 9D first contacts the sliding surface 34 of the hub ring 3, and then the side lip 92d contacts the sliding surface 34.

[0095] In the state shown in Figure 11A, the intermediate lip 92c is in a non-contact state and is not in contact with the sliding surface 34. The grease lip 92b that is in contact with the sliding surface 34 of the hub wheel 3 is deformed outward compared to the grease lip 92b in its natural state when no external force is acting on it. Also, the side lip 92d is in its natural state and is not deformed by external force.

[0096] In Figure 11A, the axial position of the outer sealing member 9D with respect to the hub wheel 3 is the fourth intermediate position in which the side lip 92d and grease lip 92b are in contact with the sliding surface 34, the intermediate lip 92c is not in contact with the sliding surface 34, and the side lip 92d is in a natural state without deformation due to external force.

[0097] At the fourth intermediate position, the side lip 92d and grease lip 92b come into contact with the sliding surface 34 of the hub wheel 3, and the intermediate lip 92c does not come into contact with the sliding surface 34, thereby forming a sealed space C surrounded by the side lip 92d and grease lip 92b of the elastic member 22 and the sliding surface 34 of the hub wheel 3.

[0098] In the outer sealing member 9D, the volume of space C when it is in the fourth intermediate position is VP4. When the outer sealing member 9D is in the fourth intermediate position, the intermediate lip 92c is not in contact with the sliding surface 34, so the space C surrounded by the side lip 92d, the grease lip 92b, and the sliding surface 34 is formed by a single space.

[0099] As shown in Figure 11B, after the side lip 92d of the outer ring 2 makes contact with the sliding surface 34, it moves outward to the normal assembly position, and the side lip 92d is pushed toward the sliding surface 34. When the side lip 92d is pushed toward the sliding surface 34, it is pressed against the sliding surface 34 and becomes deformed compared to the side lip 92d in its natural state. On the other hand, the intermediate lip 92c is in a non-contact state and is not in contact with the sliding surface 34.

[0100] In Figure 11B, the axial position of the outer sealing member 9D with respect to the hub wheel 3 is the second operating position in which the side lip 92d and grease lip 92b are in contact with the sliding surface 34, the intermediate lip 92c is not in contact with the sliding surface 34, and the side lip 92d is deformed by being pressed against the sliding surface 34.

[0101] When the outer sealing member 9D is in the second operating position, the volume of the space C enclosed by the side lip 92d, the grease lip 92b, and the sliding surface 34 is VS2. Note that when the outer sealing member 9D is in the second operating position, the intermediate lip 92c is not in contact with the sliding surface 34, so the space C enclosed by the side lip 92d, the grease lip 92b, and the sliding surface 34 is formed by a single space.

[0102] In the outer sealing member 9D, the grease lip 92b and the side lip 92d contact the sliding surface 34 when the outer sealing member 9D is in the fourth intermediate position and the second operating position, while the intermediate lip 92c does not contact the sliding surface 34 when the outer sealing member 9D is in the fourth intermediate position and the second operating position.

[0103] In a wheel bearing device 1 equipped with an outer sealing member 9D, the negative pressure parameter α is expressed by the following equation (3).

[0104] Negative pressure parameter α = (VP4 - VS2) / VP4 ... Equation (3)

[0105] In this embodiment as well, the negative pressure parameter α can be set to satisfy the relationship 0.1 ≤ α ≤ 0.6. When the negative pressure parameter α is set in this way, the relationship between volume VP4 and volume VS2 will be 0.1 ≤ (VP4 - VS2) / VP4 ≤ 0.6.

[0106] In this way, by setting the value of the negative pressure parameter α to the range of 0.1 ≤ α ≤ 0.6, it is possible to suppress the increase in torque of the outer seal member 9D assembled to the wheel bearing device 1 on the hub wheel 3.

[0107] Furthermore, in the outer sealing member 9D, the intermediate lip 92c is not in contact with the sliding surface 34 when the outer sealing member 9D is in the fourth intermediate position and the second operating position. Therefore, when the outer sealing member 9D moves from the fourth intermediate position to the second operating position, the intermediate lip 92c does not deform, and it is possible to reduce the value of the negative pressure parameter α.

[0108] [Sixth Embodiment of the Outer Seal Member] The outer seal member 9 can also be configured as the outer seal member 9E shown in Figure 12. The outer seal member 9E has a grease lip 92b located on the innermost diameter side and a side lip 92d located on the outermost diameter side. The outer seal member 9E does not have an intermediate lip located between the grease lip 92b and the side lip 92d. The outer seal member 9E is a two-lip seal having two seal lips.

[0109] As shown in Figure 12A, in the wheel bearing device 1, when the outer ring 2, with the outer side sealing member 9E fitted into the outer side opening 22, is assembled onto the hub ring 3, as the outer ring 2 moves toward the outer side, the grease lip 92b of the multiple sealing lips of the outer side sealing member 9E first contacts the sliding surface 34 of the hub ring 3, and then the side lip 92d contacts the sliding surface 34.

[0110] In the state shown in Figure 12A, the grease lip 92b in contact with the sliding surface 34 of the hub wheel 3 is deformed outward compared to the grease lip 92b in its natural state without external force acting on it. The side lip 92d is in its natural state, undeformed by external force.

[0111] In Figure 12A, the axial position of the outer sealing member 9E with respect to the hub wheel 3 is the fifth intermediate position in which the side lip 92d and grease lip 92b are in contact with the sliding surface 34, and the side lip 92d is in a natural state without deformation due to external force.

[0112] At the fifth intermediate position, the side lip 92d and grease lip 92b come into contact with the sliding contact surface 34 of the hub wheel 3, forming a sealed space C surrounded by the side lip 92d and grease lip 92b of the elastic member 22 and the sliding contact surface 34 of the hub wheel 3.

[0113] In the outer sealing member 9E, the volume of space C when it is in the fifth intermediate position is VP5. Since the outer sealing member 9E does not have an intermediate lip 92c, the space C surrounded by the side lip 92d, the grease lip 92b, and the sliding surface 34 is formed by a single space.

[0114] As shown in Figure 12B, after the side lip 92d of the outer ring 2 comes into contact with the sliding surface 34, the outer ring 2 moves toward the outer side to the normal assembly position, and the side lip 92d is pushed toward the sliding surface 34. When the side lip 92d is pushed toward the sliding surface 34, it is pressed against the sliding surface 34 and becomes deformed compared to the side lip 92d in its natural state.

[0115] In Figure 12B, the axial position of the outer sealing member 9E with respect to the hub wheel 3 is the third operating position in which the side lip 92d and grease lip 92b are in contact with the sliding surface 34, and the side lip 92d is deformed by being pressed against the sliding surface 34.

[0116] When the outer sealing member 9E is in the third operating position, the volume of the space C enclosed by the side lip 92d, the grease lip 92b, and the sliding surface 34 is VS3. Since the outer sealing member 9E does not have an intermediate lip 92c, the space C enclosed by the side lip 92d, the grease lip 92b, and the sliding surface 34 is formed by a single space.

[0117] In the outer sealing member 9E, the grease lip 92b and the side lip 92d contact the sliding surface 34 when the outer sealing member 9E is in the fifth intermediate position and the third operating position.

[0118] When the outer sealing member 9E is in the fifth intermediate position, the side lip 92d is in a natural state and is not deformed by external force. When the outer sealing member 9E is in the third operating position, the side lip 92d is deformed by being pressed against the sliding contact surface 34.

[0119] In a wheel bearing device 1 equipped with an outer side sealing member 9E, the negative pressure parameter α can be expressed by the following equation (4).

[0120] Negative pressure parameter α = (VP5 - VS3) / VP5 ... Equation (4)

[0121] In this embodiment as well, the negative pressure parameter α can be set to satisfy the relationship 0.1 ≤ α ≤ 0.6. When the negative pressure parameter α is set in this way, the relationship between volume VP5 and volume VS3 will be 0.1 ≤ (VP5 - VS3) / VP5 ≤ 0.6.

[0122] In this way, by setting the value of the negative pressure parameter α to the range of 0.1 ≤ α ≤ 0.6, it is possible to suppress the increase in torque of the outer seal member 9E assembled to the wheel bearing device 1 on the hub wheel 3.

[0123] Furthermore, since the outer sealing member 9E does not have an intermediate lip, it is possible to reduce the value of the negative pressure parameter α compared to an outer sealing member in which the intermediate lip deforms when in contact with the sliding surface 34 when in the third operating position.

[0124] [Seventh Embodiment of the Outer Seal Member] The outer seal member 9 can also be configured as the outer seal member 9F shown in Figures 13 and 14. The outer seal member 9F has a grease lip 92b located on the innermost diameter side, a side lip 92d located on the outermost diameter side, and an intermediate lip 92c located between the grease lip 92b and the side lip 92d. The outer seal member 9F is a three-lip seal having three seal lips.

[0125] As shown in Figure 13A, in the wheel bearing device 1, when the outer ring 2, with the outer side seal member 9F fitted into the outer side opening 22, is assembled onto the hub ring 3, as the outer ring 2 moves toward the outer side, the grease lip 92b, one of the multiple seal lips of the outer side seal member 9F, is the first to contact the sliding surface 34 of the hub ring 3. The grease lip 92b that has contacted the sliding surface 34 of the hub ring 3 deforms toward the outer diameter compared to the grease lip 92b in its natural state without external force acting on it.

[0126] As shown in Figure 13B, after the grease lip 92b contacts the hub ring 3, as the outer ring 2 moves further outward, the intermediate lip 92c contacts the sliding surface 34 of the hub ring 3. When the intermediate lip 92c contacts the sliding surface 34 of the hub ring 3, a second space Cb is formed, which is a sealed space surrounded by the intermediate lip 92c, the grease lip 92b, and the sliding surface 34.

[0127] As shown in Figure 13B, at the point when the intermediate lip 92c contacts the sliding surface 34, the intermediate lip 92c is in a natural state and has not been deformed by the external force. Also, the side lip 92d is not in contact with the sliding surface 34.

[0128] In Figure 13B, the axial position of the outer sealing member 9F with respect to the hub wheel 3 is the sixth intermediate position in which the grease lip 92b and the intermediate lip 92c are in contact with the sliding surface 34, the side lip 92d is not in contact with the sliding surface 34, and the intermediate lip 92c is in a natural state without deformation due to external force.

[0129] When the outer sealing member 9F is in the sixth intermediate position, the volume of the second space Cb surrounded by the intermediate lip 92c, the grease lip 92b, and the sliding surface 34 is VP6b.

[0130] As shown in Figure 14A, after the intermediate lip 92c contacts the sliding surface 34, as the outer ring 2 moves further outward, the side lip 92d contacts the sliding surface 34 of the hub ring 3. When the side lip 92d contacts the sliding surface 34 of the hub ring 3, a first space Ca is formed, which is a sealed space surrounded by the side lip 92d, the intermediate lip 92c, and the sliding surface 34.

[0131] As shown in Figure 14A, when the side lip 92d contacts the sliding surface 34, the side lip 92d is in a natural state and has not been deformed by the external force. The intermediate lip 92c is pushed toward the sliding surface 34 and, as it is pressed against the sliding surface 34, becomes deformed compared to the intermediate lip 92c which is in its natural state.

[0132] In Figure 14A, the axial position of the outer sealing member 9F with respect to the hub wheel 3 is the seventh intermediate position, where the grease lip 92b, intermediate lip 92c, and side lip 92d are in contact with the sliding surface 34, and the side lip 92d is in a natural state where it is not deformed by external force.

[0133] When the outer sealing member 9F is in the seventh intermediate position, the volume of the first space Ca1 enclosed by the intermediate lip 92c, the side lip 92d and the sliding contact surface 34 is VP7a.

[0134] As shown in Figure 14B, after the side lip 92d of the outer ring 2 contacts the sliding surface 34, it moves outward to the normal assembly position, and the side lip 92d and the intermediate lip 92c are pushed toward the sliding surface 34. When the side lip 92d is pushed toward the sliding surface 34, it is pressed against the sliding surface 34 and becomes deformed compared to the side lip 92d in its natural state. In addition, the intermediate lip 92c is pressed against the sliding surface 34 and becomes even more deformed than when the outer side sealing member 9F is in the seventh intermediate position.

[0135] In Figure 14B, the axial position of the outer sealing member 9F with respect to the hub wheel 3 is the first operating position in which the side lip 92d, intermediate lip 92c, and grease lip 92b are in contact with the sliding surface 34, and the side lip 92d and intermediate lip 92c are deformed by being pressed against the sliding surface 34.

[0136] When the outer sealing member 9F is in the first operating position, the volume of the first space Ca enclosed by the side lip 92d, the intermediate lip 92c, and the sliding surface 34 is VS1e, and when the outer sealing member 9F is in the first operating position, the volume of the second space Cb enclosed by the intermediate lip 92c, the grease lip 92b, and the sliding surface 34 is VS1f.

[0137] In a wheel bearing device 1 equipped with an outer sealing member 9F, the negative pressure parameter α can be expressed by the following equation (5).

[0138] Negative pressure parameter α = (VP6b - VS1f) / VP6b + (VP7a - VS1e) / VP7a ... Equation (5)

[0139] In this embodiment as well, the negative pressure parameter α can be set to satisfy the relationship 0.1 ≤ α ≤ 0.6. When the negative pressure parameter α is set in this way, the volumes VP6b, VP7a, VS1e, and VS1f will have the relationship 0.1 ≤ (VP6b - VS1f) / VP6b + (VP7a - VS1e) / VP7a ≤ 0.6.

[0140] In this way, by setting the value of the negative pressure parameter α to the range of 0.1 ≤ α ≤ 0.6, it is possible to suppress the increase in torque of the outer sealing member 9F assembled to the wheel bearing device 1 on the hub wheel 3.

[0141] Although embodiments of the present invention have been described above, the present invention is not limited in any way to these embodiments, but is merely illustrative. It can be implemented in various other forms without departing from the spirit of the invention, and the scope of the present invention is indicated by the claims, and further includes all modifications within the meaning and scope of equivalents as described in the claims.

[0142] This invention can be used in wheel bearing devices.

[0143] 1 Wheel bearing device 2 Outer ring 3 Hub ring 4 Inner ring 5 Inner ball row 6 Outer ball row 9, 9A, 9B, 9C, 9D, 9E, 9F Outer seal member 22 Outer opening 23 Outer raceway surface (inner side) 24 Outer raceway surface (outer side) 32 Wheel mounting flange 33 Inner raceway surface (outer side) 41 Inner raceway surface (inner side) 34 Sliding surface 34a Axial surface 34b Radial surface 34c Connecting surface 91 Core metal 92 Elastic member 92b Grease lip 92c Intermediate lip 92d Side lip P1 First contact point P2 Second contact point VP1a Volume (of the space enclosed by the side lip and intermediate lip and the sliding surface when the outer seal member is in the first intermediate position) VP1b Volume VP2 of the space enclosed by the intermediate lip and grease lip and the sliding surface when the outer seal member is in the first intermediate position Volume VP3a of the space enclosed by the grease lip and side lip and the sliding surface when the outer seal member is in the second intermediate position Volume VP3b of the space enclosed by the side lip and intermediate lip and the sliding surface when the outer seal member is in the third intermediate position Volume VP4 of the space enclosed by the intermediate lip and grease lip and the sliding surface when the outer seal member is in the third intermediate position Volume VP5 of the space enclosed by the grease lip and side lip and the sliding surface when the outer seal member is in the fourth intermediate position Volume VP6b of the space enclosed by the grease lip and side lip and the sliding surface when the outer seal member is in the fifth intermediate position Volume VP7a (Volume of the space enclosed by the side lip and intermediate lip and the sliding surface when the outer sealing member is in the seventh intermediate position) VS1a, VS1c, VS1e (Volume of the space enclosed by the side lip and intermediate lip and the sliding surface when the outer sealing member is in the first use position)VS1b, VS1d, VS1f: Volume of the space enclosed by the intermediate lip and grease lip and the sliding surface when the outer seal member is in the first use position. VS2: Volume of the space enclosed by the grease lip and side lip and the sliding surface when the outer seal member is in the second use position. VS3: Volume of the space enclosed by the grease lip and side lip and the sliding surface when the outer seal member is in the third use position. R: Radius of curvature.

Claims

1. A wheel bearing device comprising: an outer member having double rows of outer raceway surfaces on its inner circumference; a hub ring having a wheel mounting flange on one axial side for mounting a wheel and a small diameter stepped portion extending axially on its outer circumference; and an inner member having double rows of inner raceway surfaces facing the double rows of outer raceway surfaces, and consisting of at least one inner ring press-fitted into the small diameter stepped portion of the hub ring; double rows of rolling elements rotatably housed between the two raceway surfaces of the outer member and the inner member; and a sealing device fitted to the outer member and closing the axial opening end on one side of the annular space formed by the outer member and the inner member, wherein the sealing device comprises a core metal fitted to one axial side of the outer member and an elastic member joined to the core metal and having a plurality of seal lips extending toward the hub ring, and the hub ring has a sliding contact surface at the base end of the wheel mounting flange in contact with the seal lips of the elastic member. The seal lip has a grease lip located on the innermost diameter side, a side lip located on the outermost diameter side, and an intermediate lip located between the grease lip and the side lip, and when the axial position of the sealing device with respect to the hub wheel is at a first intermediate position in which the grease lip, the intermediate lip, and the side lip are in contact with the sliding surface and the side lip is in a natural state not deformed by external force, the volume VP1a of the space enclosed by the side lip and the intermediate lip and the sliding surface, and the volume VP1b of the space enclosed by the intermediate lip and the grease lip and the sliding surface, A wheel bearing device in which, when the axial position of the sealing device with respect to the hub wheel is in a first operating position in which the grease lip, the intermediate lip, and the side lip are in contact with the sliding surface and the side lip and the intermediate lip are deformed by being pressed against the sliding surface, the volume VS1a of the space enclosed by the side lip and the intermediate lip and the sliding surface, and the volume VS1b of the space enclosed by the intermediate lip and the grease lip and the sliding surface, satisfy the relationship 0.1 ≤ (VP1a - VS1a) / VP1a + (VP1b - VS1b) / VP1b ≤ 0.

6.

2. A wheel bearing device comprising: an outer member having double rows of outer raceway surfaces on its inner circumference; a hub ring having a wheel mounting flange on one axial side for mounting a wheel and a small-diameter stepped portion extending axially on its outer circumference; and an inner member having double rows of inner raceway surfaces facing the double rows of outer raceway surfaces, and comprising at least one inner ring press-fitted into the small-diameter stepped portion of the hub ring; double rows of rolling elements rotatably housed between the two raceway surfaces of the outer member and the inner member; and a sealing device fitted to the outer member and closing the axial opening end on one side of the annular space formed by the outer member and the inner member, wherein the sealing device comprises a core metal fitted to one axial side of the outer member and an elastic member joined to the core metal and having a plurality of seal lips extending toward the hub ring, and the hub ring has a sliding contact surface at the base end of the wheel mounting flange in contact with the seal lips of the elastic member. The seal lip has a grease lip located on the innermost diameter side, a side lip located on the outermost diameter side, and an intermediate lip located between the grease lip and the side lip, and the volume VP2 of the space enclosed by the grease lip, the side lip and the sliding surface when the axial position of the sealing device with respect to the hub wheel is at a second intermediate position in which the grease lip and the side lip are in contact with the sliding surface, the intermediate lip is not in contact with the sliding surface, and the side lip is in a natural state not deformed by external force, and the volume VP3a of the space enclosed by the side lip, the intermediate lip and the sliding surface and the volume VP3b of the space enclosed by the intermediate lip, the grease lip and the sliding surface when the axial position of the sealing device with respect to the hub wheel is at a third intermediate position in which the grease lip, the intermediate lip and the side lip are in contact with the sliding surface, and the intermediate lip is in a natural state not deformed by external force,A wheel bearing device in which, when the axial position of the sealing device with respect to the hub wheel is in a first operating position in which the grease lip, the intermediate lip, and the side lip are in contact with the sliding surface and the side lip and the intermediate lip are deformed by being pressed against the sliding surface, the volume VS1c of the space enclosed by the side lip and the intermediate lip and the sliding surface, and the volume VS1d of the space enclosed by the intermediate lip and the grease lip and the sliding surface, satisfy the relationship 0.1 ≤ (VP2 - (VP3a + VP3b)) / VP2 + (VP3a - VS1c) / VP3a + (VP3b - VS1d) / VP3b ≤ 0.

6.

3. A wheel bearing device comprising: an outer member having double rows of outer raceway surfaces on its inner circumference; a hub ring having a wheel mounting flange for mounting a wheel on one axial side and a small-diameter stepped portion extending axially on its outer circumference; and an inner member having double rows of inner raceway surfaces facing the double rows of outer raceway surfaces, comprising at least one inner ring press-fitted into the small-diameter stepped portion of the hub ring; double rows of rolling elements rotatably housed between the two raceway surfaces of the outer member and the inner member; and a sealing device fitted to the outer member and closing the axial opening end on one side of the annular space formed by the outer member and the inner member, wherein the sealing device comprises a core metal fitted to one axial side of the outer member and an elastic member joined to the core metal and having a plurality of seal lips extending toward the hub ring, and the hub ring has a sliding contact surface at the base end of the wheel mounting flange in contact with the seal lips of the elastic member. The seal lip has a grease lip located on the innermost diameter side, a side lip located on the outermost diameter side, and an intermediate lip located between the grease lip and the side lip, and the wheel bearing device has the following relationship: VP4 is the volume of the space enclosed by the side lip, the grease lip and the sliding surface when the axial position of the sealing device with respect to the hub wheel is a fourth intermediate position in which the grease lip and the side lip are in contact with the sliding surface, the intermediate lip is not in contact with the sliding surface, and the side lip is in a natural state not deformed by external force; VS2 is the volume of the space enclosed by the side lip, the grease lip and the sliding surface when the axial position of the sealing device with respect to the hub wheel is a second operating position in which the grease lip and the side lip are in contact with the sliding surface, the intermediate lip is not in contact with the sliding surface, and the side lip is deformed by being pressed against the sliding surface; and VS2 is the volume of the space enclosed by the side lip, the grease lip and the sliding surface when the axial position of the sealing device with respect to the hub wheel is a second operating position in which the grease lip and the side lip are in contact with the sliding surface, the intermediate lip is not in contact with the sliding surface, and the side lip is deformed by being pressed against the sliding surface; and 0.1 ≤ (VP4 - VS2) / VP4 ≤ 0.

6.

4. A wheel bearing device comprising: an outer member having double rows of outer raceway surfaces on its inner circumference; a hub ring having a wheel mounting flange on one axial side for mounting a wheel and a small diameter stepped portion extending axially on its outer circumference; and an inner member having double rows of inner raceway surfaces facing the double rows of outer raceway surfaces, and consisting of at least one inner ring press-fitted into the small diameter stepped portion of the hub ring; double rows of rolling elements rotatably housed between the two raceway surfaces of the outer member and the inner member; and a sealing device fitted to the outer member and closing the axial opening end on one side of the annular space formed by the outer member and the inner member, wherein the sealing device comprises a core metal fitted to one axial side of the outer member and an elastic member joined to the core metal and having a plurality of seal lips extending toward the hub ring, and the hub ring has a sliding contact surface at the base end of the wheel mounting flange in contact with the seal lips of the elastic member. The seal lip has a grease lip located on the innermost diameter side and a side lip located on the outermost diameter side, and the wheel bearing device has the following relationship: VP5 is the volume of the space enclosed by the side lip and the grease lip and the sliding surface when the axial position of the sealing device with respect to the hub wheel is a fifth intermediate position in which the grease lip and the side lip are in contact with the sliding surface and the side lip is in a natural state not deformed by external force; and VS3 is the volume of the space enclosed by the side lip and the grease lip and the sliding surface when the axial position of the sealing device with respect to the hub wheel is a third operating position in which the grease lip and the side lip are in contact with the sliding surface and the side lip is deformed by being pressed against the sliding surface, and 0.1 ≤ (VP5 - VS3) / VP5 ≤ 0.6 5. A wheel bearing device comprising: an outer member having double rows of outer raceway surfaces on its inner circumference; a hub ring having a wheel mounting flange for mounting a wheel on one axial side and a small-diameter stepped portion extending axially on its outer circumference; and an inner member having double rows of inner raceway surfaces facing the double rows of outer raceway surfaces, and comprising at least one inner ring press-fitted into the small-diameter stepped portion of the hub ring; double rows of rolling elements rotatably housed between the two raceway surfaces of the outer member and the inner member; and a sealing device fitted to the outer member and closing the axial opening end on one side of the annular space formed by the outer member and the inner member, wherein the sealing device comprises a core metal fitted to one axial side of the outer member and an elastic member joined to the core metal and having a plurality of seal lips extending toward the hub ring, and the hub ring has a sliding contact surface at the base end of the wheel mounting flange in contact with the seal lips of the elastic member. The seal lip has a grease lip located on the innermost diameter side, a side lip located on the outermost diameter side, and an intermediate lip located between the grease lip and the side lip, and the volume VP6b of the space enclosed by the grease lip, the intermediate lip and the sliding surface when the axial position of the sealing device with respect to the hub wheel is at a sixth intermediate position in which the grease lip and the intermediate lip are in contact with the sliding surface, the side lip is not in contact with the sliding surface, and the intermediate lip is in a natural state not deformed by external force, and the volume VP7a of the space enclosed by the intermediate lip, the side lip and the sliding surface when the axial position of the sealing device with respect to the hub wheel is at a seventh intermediate position in which the grease lip, the intermediate lip and the side lip are in contact with the sliding surface, and the side lip is in a natural state not deformed by external force, When the axial position of the sealing device with respect to the hub wheel is in the first operating position, in which the grease lip, the intermediate lip, and the side lip are in contact with the sliding surface and the side lip and the intermediate lip are deformed by being pressed against the sliding surface, the volume VS1e of the space enclosed by the side lip and the intermediate lip and the sliding surface, and the volume VS1f of the space enclosed by the intermediate lip and the grease lip and the sliding surface are,A wheel bearing device having the relationship 0.1 ≤ (VP6b - VS1f) / VP6b + (VP7a - VS1e) / VP7a ≤ 0.

6.

6. The wheel bearing device according to any one of claims 1, 2, and 5, wherein the sliding surface has an axial surface along the axial direction, a radial surface along the radial direction perpendicular to the axial direction, and a connecting surface connecting the axial surface and the radial surface, and when the sealing device is in the first operating position, the side lip and the intermediate lip contact the radial surface of the sliding surface, and the grease lip contacts the axial surface of the sliding surface.

7. The wheel bearing device according to any one of claims 1, 2, and 5, wherein the sliding surface has an axial surface along the axial direction, a radial surface along the radial direction perpendicular to the axial direction, and a connecting surface connecting the axial surface and the radial surface, and when the sealing device is in the first operating position, the side lip contacts the radial surface on the sliding surface, and the grease lip and the intermediate lip contact the axial surface on the sliding surface.

8. The wheel bearing device according to any one of claims 1 to 5, wherein the sliding contact surface has an arcuate surface with a radius of curvature R of 4.0 mm or less between a first contact point in contact with the grease lip and a second contact point in contact with the side lip.

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