Wheel bearing device

Abstract

To provide a wheel bearing device capable of suppressing an increase in pressure in an annular gap between an outward member and an inward member without increasing the cost of an inner side sealing device.SOLUTION: An inner side sealing device 10 of a wheel bearing device 1 includes: a seal member 13 having a core grid 11 consisting of an inner fitting part 111 and a side plate part 112, and an elastic member 12; and a slinger 14 having an outer fitting part 141 and an annular part 142. The inner fitting part 111 includes an outer peripheral contact surface 111a that comes in contact with an inner peripheral surface of an outer ring 2, and a ventilation groove 111c formed on the outer peripheral contact surface 111a, which extends from an outer side end of the outer peripheral contact surface 111a toward the inner side. An axial length A of the ventilation groove 111c and an axial length B of the outer peripheral contact surface 111a satisfy the relationships of A<B, and an axial length C from an outer side end of the core grid 11 to an inner side end of the ventilation groove 111c and an axial length D from the outer side end of the core grid 11 to an inner side end of the seal member 13 satisfy the relationships of C<(D / 2).SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] A wheel bearing device that rotatably supports a wheel in a suspension system of an automobile, etc. is known. The wheel bearing device is provided with a sealing device that closes an open end of an annular space formed by an outer member and an inner member to prevent foreign matter such as muddy water from entering.

[0003] For example, in the wheel bearing device disclosed in Patent Document 1, a three-lip seal is provided as an outer-side sealing device that closes the outer opening end of the annular space between the outer member and the inner member, and a pack seal is provided as an inner-side sealing device that closes the inner opening end of the annular space between the outer member and the inner member.

[0004] The wheel bearing device in Patent Document 1 comprises an outer member having a double-row outer raceway surface, a hub wheel having a small diameter step, and an inner ring press-fitted into the small diameter step of the hub wheel, and is equipped with an inner member having a double-row inner raceway surface facing the double-row outer raceway surface, double-row rolling elements accommodated between the raceway surfaces of the outer member and the inner member so as to be able to roll freely, and an outer side sealing device and an inner side sealing device.

[0005] In the assembly process of such a wheel bearing device, typically, an outer sealing device is press-fitted into an outer member into which double rows of rolling elements are attached and into which grease is sealed, the outer member is then attached to a hub wheel, an inner ring is press-fitted into the hub wheel, and finally an inner sealing device is press-fitted between the outer member and the inner member to complete the assembly.

[0006] The inner sealing device also includes a core bar consisting of an inner fitting portion that is fitted into the inner circumference of the outer ring, which is the outer member, and a side plate portion extending from the inner fitting portion toward the inner diameter side, and a seal member having an elastic member that is integrally joined to the core bar and has multiple seal lips formed thereon, and a slinger having an outer fitting portion that is fitted into the outer circumference of the inner ring, which is the inner member, and a circular ring portion that extends from the outer fitting portion toward the outer diameter side and faces the side plate portion of the core bar in the axial direction.

[0007] When the inner sealing device having such a configuration is press-fitted between the outer member and the inner member in the assembly process, air is forced into the annular space between the outer member and the inner member, and the internal pressure of the annular space increases by an amount equivalent to the volume of the press-fitted inner sealing device.

[0008] When the internal pressure in the annular space increases, the internal pressure in the annular space causes the radial lip of the inner sealing device to deform so as to stick to the slinger, and the radial lip of the outer sealing device to deform so as to stick to the seal land of the hub wheel, thereby increasing the sealing torque of the inner sealing device and the outer sealing device.

[0009] Therefore, Patent Document 2 proposes forming an air passage in the core metal of the outer sealing device, connecting the inside and outside of the wheel bearing device, to mitigate the pressure increase in the annular space between the outer member and the inner member.

[0010] Furthermore, Patent Document 1 discloses that, in order to prevent a space surrounded by the seal lip and slinger of the inner sealing device from becoming negative pressure and sticking to the slinger, an air passage is formed on the seal lip sliding surface of the slinger in the inner sealing device, thereby enabling the space surrounded by the seal lip and slinger of the inner sealing device to communicate with the external space.

[0011] The air passage formed in the slinger is configured to connect the space surrounded by the seal lip and the slinger to the external space before the inner sealing device is pressed in, and to isolate the space surrounded by the seal lip and the slinger from the external space after the inner sealing device is completely pressed in. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] Patent Publication No. 2021-63563 [Patent Document 2] Patent Publication No. 2021-8948 Summary of the Invention [Problem to be solved by the invention]

[0013] However, in the inner sealing device described in Patent Document 1, it is necessary to additionally process an air passage on the seal lip sliding surface of the slinger, which may increase the cost of the inner sealing device. Also, depending on the position of the tip of the seal lip after completion of press-fitting of the inner sealing device, the tip of the seal lip may come into contact with the seal lip sliding surface at the position of the air passage, which may cause foreign matter such as muddy water to enter the inner sealing device through the air passage or cause grease inside the inner sealing device to leak to the outside.

[0014] Furthermore, in the inner sealing device described in Patent Document 2, it is necessary to additionally process an air passage in the core metal, which may increase the cost of the inner sealing device.

[0015] The present invention has been made in consideration of the above-mentioned circumstances, and provides a wheel bearing device that can suppress pressure rise in the annular space between an outer member and an inner member without increasing the cost of the inner sealing device. [Means for solving the problem]

[0016] That is, the wheel bearing device includes an outer member having a double-row outer raceway surface on its inner circumference, a hub ring having 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. The inner member has a double-row inner raceway surface facing the double-row outer raceway surface, a double-row of rolling elements rotatably accommodated between both raceway surfaces of the outer member and the inner member, and a sealing device closing an open end on one axial end side of an annular space formed by the outer member and the inner member, or an open end on the other axial end side of the annular space. The sealing device includes a core metal composed of a fitting portion fitted to the inner circumference of the outer member and a side plate portion extending from the fitting portion toward the inner diameter side, and a seal member having an elastic member joined to the core metal, and a slinger extending from an outer fitting portion fitted to the outer circumference of the inner member toward the outer diameter side. The fitting portion has an outer circumferential contact surface contacting the inner circumferential surface of the outer member, and a ventilation groove formed in the outer circumferential contact surface and extending axially outward from an axially inner end of the outer circumferential contact surface. The axial length A of the ventilation groove and the axial length B of the outer circumferential contact surface have a relationship of A < B. The axial length C from the axially inner end of the core metal to the axially outer end of the ventilation groove and the axial length D from the axially inner end of the core metal to the axially outer end of the seal member have a relationship of C < (D / 2).

Effect of the Invention

[0017] According to the present invention, it is possible to suppress an increase in pressure in the annular space between the outer member and the inner member without increasing the cost of the inner side sealing device.

Brief Description of the Drawings

[0018] [Figure 1] It is a side cross-sectional view showing a wheel bearing device. [Diagram 2] It is a side cross-sectional view showing an inner side sealing device. [Diagram 3] It is a cross-sectional view of the fitting portion of the core metal with the ventilation groove viewed axially. [Figure 4] It is a side cross-sectional view showing a wheel bearing device before the inner side sealing device is press-fitted between the outer ring and the inner ring. [Diagram 5] 4 is a side cross-sectional view showing the wheel bearing device at the start of press-fitting of the inner sealing device. FIG. [Figure 6] 4 is a side cross-sectional view showing the inner sealing device at the start of press-fitting into the wheel bearing device. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0020] [Wheel bearing device] A wheel bearing device 1 shown in FIG. 1 is one embodiment of a wheel bearing device according to the present invention, and supports a wheel rotatably in a suspension system of a vehicle such as an automobile.

[0021] In the following description, the axial direction refers to the direction along the rotation axis X of the wheel support bearing device 1. The inner side refers to one axial end side, which is the vehicle body side of the wheel support bearing device 1 when attached to the vehicle body, and the outer side refers to the other axial end side, which is the wheel side of the wheel support bearing device 1 when attached to the vehicle body. Furthermore, the axial inner side refers to the direction toward the inside of the wheel support bearing device 1 in the axial direction, and the axial outer side refers to the direction toward the outside of the wheel support bearing device 1 in the axial direction.

[0022] The wheel bearing device 1 has a configuration called third generation, and includes an outer ring 2 as an outer member, a hub ring 3 and an inner ring 4 as inner members, two rolling rows of inner ball rows 5 and outer ball rows 6, an outer seal member 9, and an inner sealing device 10. In this embodiment, a three-lip seal is used as the outer seal member 9, and a pack seal is used as the inner sealing device 10.

[0023] An inner side opening 2a is formed at an inner side end of the outer ring 2, into which an inner side sealing device 10 can be fitted. An outer side opening 2b is formed at an outer side end of the outer ring 2, into which an outer side seal member 9 can be fitted.

[0024] The inner-side sealing device 10 is fitted into the inner-side opening 2a to close the inner-side opening end of the annular space S formed by the outer ring 2, which is the outer member, and the hub ring 3 and inner ring 4, which are the inner members. The outer-side seal member 9 is fitted into the outer-side opening 2b to close the outer-side opening end of the annular space S.

[0025] The inner sealing device 10 and the outer sealing member 9 are members that close the open ends of the annular space S. In this manner, by closing the open ends on the inner side and the outer side of the annular space S with the inner sealing device 10 and the outer sealing member 9, foreign matter such as muddy water is prevented from entering the inside of the wheel bearing device 1.

[0026] An inner-side outer raceway surface 2c and an outer-side outer raceway surface 2d are formed on the inner peripheral surface of the outer ring 2. A vehicle body mounting flange 2e for mounting the outer ring 2 to a vehicle body member is integrally formed on the outer peripheral surface of the outer ring 2. The vehicle body mounting flange 2e is provided with bolt holes 2f into which fastening members (here, bolts) for fastening the outer ring 2 to the vehicle body member are inserted.

[0027] The inner end of the outer circumferential surface of the hub wheel 3 is formed with a small diameter step 3a that is smaller in diameter than the outer end. A wheel mounting flange 3b for mounting a wheel is formed integrally with the outer end of the hub wheel 3. A plurality of bolt holes 3e are formed in the wheel mounting flange 3b. Hub bolts 3f for fastening the hub wheel 3 to a wheel or a brake component can be press-fitted into the bolt holes 3e.

[0028] In the hub wheel 3, a sliding surface 3d with which the outer seal member 9 slides is formed on the base side of the wheel mounting flange 3b. An outer inner raceway surface 3c is provided on the outer peripheral surface of the hub wheel 3 so as to face the outer outer raceway surface 2d on the outer side of the outer ring 2. In other words, the hub wheel 3 forms the inner raceway surface 3c on the outer side of the inner member.

[0029] An inner ring 4 is provided on the small diameter step 3a of the hub ring 3. The inner ring 4 is fixed to the small diameter step 3a of the hub ring 3 by press fitting. An inner-side inner raceway surface 4a is provided on the outer peripheral surface of the inner ring 4 so as to face the inner-side outer raceway surface 2c of the outer ring 2. In other words, the inner ring 4 forms the inner raceway surface 4a on the inner side of the inner member.

[0030] The inner ball row 5 and the outer ball row 6, which are rolling rows, are formed by a plurality of balls 7, which are rolling elements, being held by a cage 8. The inner ball row 5 is rollably sandwiched between the inner raceway surface 4a of the inner ring 4 and the inner-side outer raceway surface 2c of the outer ring 2. The outer ball row 6 is rollably sandwiched between the inner raceway surface 3c of the hub ring 3 and the outer raceway surface 2d of the outer ring 2. In other words, the inner ball row 5 and the outer ball row 6 are rollably housed between the raceway surfaces of the outer member and the inner member.

[0031] In the wheel bearing device 1, a double-row angular ball bearing is formed by the outer ring 2, hub ring 3, inner ring 4, inner ball row 5, and outer ball row 6. Note that the wheel bearing device 1 may be formed as a double-row tapered roller bearing instead of the double-row angular ball bearing.

[0032] [Inner sealing device] As shown in Figure 2, the inner sealing device 10 includes a seal member 13 having a core bar 11 fitted into the outer ring 2 and an elastic member 12 joined to the core bar 11, a slinger 14 fitted into the inner ring 4, and a magnetic encoder 15 joined to the slinger 14.

[0033] The core bar 11 is made of, for example, a steel plate, and consists of a cylindrical inner fitting portion 111 that fits into the inner circumference of the inner side opening 2a of the outer ring 2, and an annular side plate portion 112 that extends from the outer side end of the inner fitting portion 111 toward the inner diameter side.

[0034] The inner fitting portion 111 has an outer peripheral contact surface 111a that contacts the inner peripheral surface at the inner side opening 2a of the outer ring 2, an inner side outer peripheral surface 111b that is formed continuous with the inner side of the outer peripheral contact surface 111a and has a smaller diameter than the outer peripheral contact surface 111a, and an air groove 111c formed in the outer peripheral contact surface 111a.

[0035] The outer contact surface 111a of the inner fitting portion 111 of the core wire 11 comes into contact with the inner surface of the inner side opening 2a of the outer ring 2, thereby sealing the annular space S of the wheel bearing device 1 and preventing the grease filled in the annular space S from leaking out from between the outer ring 2 and the inner side sealing device 10.

[0036] The elastic member 12 is made of, for example, synthetic rubber, and is integrally joined to the core metal 11 by vulcanization adhesion. The elastic member 12 has a base 121 that is vulcanization-adhered to the core metal 11, and a first side lip 122, a second side lip 123, and a grease lip 124 that extend from the base 121 and are each formed in an annular shape. The first side lip 122, the second side lip 123, and the grease lip 124 are seal lips that the elastic member 12 has.

[0037] The base 121 is joined to the inner peripheral surface, inner end face, and inner outer peripheral surface 111b of the inner fitting portion 111, and to an inner side surface which is one axial side surface, an inner diameter side end face, and an inner diameter side portion of an outer side surface which is the other axial side surface of the side plate portion 112. The portion of the base 121 joined to the inner outer peripheral surface 111b has a pressure contact portion 121a which is in pressure contact with the inner peripheral surface of the inner opening 2a of the outer ring 2.

[0038] The pressure-contact portion 121a at the base 121 of the elastic member 12 is pressed against the inner surface of the inner side opening 2a of the outer ring 2, thereby preventing foreign matter such as muddy water from the outside from entering the annular space S of the wheel bearing device 1 from between the outer ring 2 and the inner side sealing device 10.

[0039] The first side lip 122 is located on the outermost side of the seal lips of the elastic member 12, and extends from the base 121 toward the outer diameter side and the inner side. The second side lip 123 is located on the inner diameter side of the first side lip 122, and extends from the base 121 toward the outer diameter side and the inner side. The grease lip 124 is located on the inner diameter side of the second side lip 123, and extends from the base 121 toward the inner diameter side and the outer side.

[0040] The slinger 14 is made of, for example, a steel plate, and has a cylindrical outer fitting portion 141 that fits onto the outer peripheral surface at the inner end portion of the inner ring 4, and an annular portion 142 that extends from the inner end portion of the outer fitting portion 141 toward the outer diameter side.

[0041] The annular portion 142 of the slinger 14 is located on the inner side of the side plate portion 112 of the core bar 11 in the axial direction, and the annular portion 142 and the side plate portion 112 face each other in the axial direction.

[0042] The first side lip 122 of the elastic member 12 faces the annular portion 142 of the slinger 14 in the axial direction, and the tip of the first side lip 122 is in slidable contact with the annular portion 142. In other words, the first side lip 122 is a contact lip.

[0043] The second side lip 123 of the elastic member 12 faces the annular portion 142 of the slinger 14 in the axial direction, and the tip of the second side lip 123 is in slidable contact with the annular portion 142. In other words, the second side lip 123 is a contact lip.

[0044] The grease lip 124 of the elastic member 12 faces the outer fitting portion 141 of the slinger 14 in the radial direction, and the tip end of the grease lip 124 is in slidable contact with the outer fitting portion 141. In other words, the grease lip 124 is a contact lip.

[0045] The first side lip 122 and the second side lip 123 are seal lips that extend in the axial direction from the base 121 of the elastic member 12 toward the annular portion 142 of the slinger 14. The grease lip 124 is a seal lip that extends in the radial direction from the base 121 of the elastic member 12 toward the outer fitting portion 141 of the slinger 14.

[0046] The magnetic encoder 15 is joined to the inner side surface of the annular portion 142 of the slinger 14. The magnetic encoder 15 is formed of synthetic rubber mixed with magnetic powder such as ferrite, and is integrally joined to the annular portion 142 of the slinger 14 by vulcanization adhesion. The magnetic encoder 15 is vulcanization-adhered to the slinger 14 by, for example, insert molding together with the slinger 14.

[0047] The magnetic encoder 15 is magnetized with N poles and S poles alternately arranged at equal pitch in the circumferential direction. The rotation speed of the inner ring 4 can be detected by detecting changes in the magnetic flux density of the magnetic encoder 15 using a rotation speed sensor disposed opposite the magnetic encoder 15.

[0048] In this embodiment, the inner sealing device 10 is provided with the magnetic encoder 15, but the inner sealing device 10 may be configured not to include the magnetic encoder 15.

[0049] [Ventilation groove] The ventilation groove 111c in the inner fitting portion 111 of the core bar 11 extends along the axial direction from the outer side end which is the axially inner end of the outer circumferential contact surface 111a toward the inner side which is the axially outer side.

[0050] The ventilation groove 111c is formed from the outer side end of the outer peripheral contact surface 111a to the middle part in the axial direction of the outer peripheral contact surface 111a. In the portion of the inner fitting part 111 where the ventilation groove 111c is formed, there is a space surrounded by the ventilation groove 111c and the inner peripheral surface of the outer ring 2. In a state where the inner side sealing device 10 is press-fitted between the outer ring 2 and the inner ring 4, the outer side end of the ventilation groove 111c is open to the annular space S, and the inner side end of the ventilation groove 111c is closed.

[0051] In the present embodiment, the cross-sectional shape of the ventilation groove 111c as viewed from the axial direction is formed in a semi-circular shape. However, the cross-sectional shape of the ventilation groove 111c as viewed from the axial direction is not limited to this, and it can be formed in any shape such as a V-shaped, U-shaped, or rectangular shape.

[0052] The axial length of the ventilation groove 111c is A, and the axial length of the outer peripheral contact surface 111a is B. The axial length A of the ventilation groove 111c and the axial length B of the outer peripheral contact surface 111a have a relationship of A < B. That is, the axial length A of the ventilation groove 111c is formed shorter than the axial length B of the outer peripheral contact surface 111a.

[0053] Also, the axial length A of the ventilation groove 111c and the axial length B of the outer peripheral contact surface 111a have a relationship of A ≧ (B / 2). That is, the axial length A of the ventilation groove 111c is formed to be half or more of the axial length B of the outer peripheral contact surface 111a.

[0054] The axial length from the outer side end, which is the inner side end in the axial direction of the core metal 11, to the inner side end, which is the outer side end in the axial direction of the ventilation groove 111c, is C. Also, the axial length from the outer side end, which is the inner side end in the axial direction of the core metal 11, to the inner side end, which is the outer side end in the axial direction of the seal member 13, is D.

[0055] The axial length C from the outer end of the core metal 11 to the inner end of the ventilation groove 111c and the axial length D from the outer end of the core metal 11 to the inner end of the seal member 13 have the relationship C<(D / 2). In other words, the axial length C from the outer end of the core metal 11 to the inner end of the ventilation groove 111c is set to be less than half the axial length D from the outer end of the core metal 11 to the inner end of the seal member 13.

[0056] The inner fitting portion 111 has a radial thickness of t, and the ventilation groove 111c has a radial depth of d. The thickness t of the inner fitting portion 111 and the depth d of the ventilation groove 111c have a relationship of d≦(t / 2).

[0057] That is, the depth d of the ventilation groove 111c is formed to be equal to or less than half the thickness t of the internal fitting portion 111. By forming the depth d of the ventilation groove 111c to be equal to or less than half the thickness t of the internal fitting portion 111, it is possible to suppress a decrease in strength of the internal fitting portion 111 due to the formation of the ventilation groove 111c.

[0058] The ventilation groove 111c may be formed in at least one location on the outer peripheral contact surface 111a, and it is preferable that the ventilation groove 111c is formed in a plurality of locations in the circumferential direction on the outer peripheral contact surface 111a.

[0059] [Press-fitting the inner sealing device into the wheel bearing device 1] In the assembly process for assembling the wheel bearing device 1, first, the inner ball row 5 and the outer ball row 6 are attached to the outer ring 2 and grease is filled in. Next, the outer seal member 9 is press-fitted into the outer opening 2b of the outer ring 2. After that, the outer ring 2 is attached to the hub ring 3, and the inner ring 4 is press-fitted into the small diameter step 3a of the hub ring 3.

[0060] As shown in Figure 4, after the inner ring 4 is pressed into the small diameter step 3a of the hub wheel 3, the inner side sealing device 10 is pressed between the inner side opening 2a of the outer ring 2 and the inner ring 4, thereby completing the assembly of the wheel bearing device 1.

[0061] When the inner sealing device 10 is pressed in, the hub wheel 3 is placed on the support base with its axial direction vertical and its outer end portion positioned downward, and the inner sealing device 10 is pressed in from above the wheel bearing device 1 between the inner opening 2a of the outer ring 2 and the inner ring 4.

[0062] As shown in Figure 5, when the inner sealing device 10 starts to be pressed into between the outer ring 2 and the inner ring 4, the core metal 11 of the inner sealing device 10 has its outer end fitted into the outer ring 2.

[0063] As shown in FIG. 6, specifically, at the start of pressing in the inner sealing device 10, the outer end of the outer circumferential contact surface 111a of the inner fitting portion 111 of the core metal 11 is fitted into the inner opening 2a of the outer ring 2.

[0064] In this state, the outer end of the ventilation groove 111c formed in the outer peripheral contact surface 111a is fitted into the outer ring 2, but the inner end of the ventilation groove 111c is located on the inner side of the outer ring 2 and is open to the outside. Therefore, the annular space S of the wheel support bearing device 1 communicates with the outside of the wheel support bearing device 1 through the ventilation groove 111c.

[0065] When the inner sealing device 10 is pressed in, an amount of air corresponding to the volume of the inner sealing device 10 is forced into the annular space S. However, the air forced into the annular space S by pressing in the inner sealing device 10 can escape to the outside of the wheel bearing device 1 through the ventilation groove 111c. Therefore, by forming the ventilation groove 111c in the outer circumferential contact surface 111a, an increase in the internal pressure of the annular space S can be suppressed.

[0066] In other words, the air in the annular space S can escape to the outside of the wheel bearing device 1 until the inner end of the ventilation groove 111c is fitted into the outer ring 2, thereby making it possible to reduce the increase in internal pressure in the annular space S when the inner sealing device 10 is completely pressed into between the inner opening 2a of the outer ring 2 and the inner ring 4.

[0067] In this case, since the axial length A of the ventilation groove 111c is equal to or more than half the axial length B of the outer circumferential contact surface 111a, the volume of the inner-side sealing device 10 involved in the increase in internal pressure in the annular space S can be reduced to less than half of the volume in the case where the ventilation groove 111c is not formed in the outer circumferential contact surface 111a. This makes it possible to prevent the grease slip 124 from deforming and sticking to the slinger 14 due to an increase in internal pressure in the annular space S, and to mitigate an increase in the seal torque of the inner-side sealing device 10.

[0068] Incidentally, when the ventilation groove 111c is not formed on the outer peripheral contact surface 111a, the internal pressure of the annular space S generally rises by about 20 kPa to 40 kPa when the inner sealing device 10 is pressed in, but it is possible to suppress this internal pressure rise to less than half.

[0069] In addition, the ventilation groove 111c extends from the outer end of the outer peripheral contact surface 111a to the inner side, and since the axial length A of the ventilation groove 111c is shorter than the axial length B of the outer peripheral contact surface 111a, the outer peripheral contact surface 111a that contacts the inner peripheral surface of the outer ring 2 is located on the inner side of the ventilation groove 111c.

[0070] Therefore, compared to when the ventilation groove 111c is formed over the entire axial area of ​​the outer circumferential contact surface 111a, it is possible to prevent the grease sealed in the annular space S from leaking out of the wheel bearing device 1 through the ventilation groove 111c after the inner sealing device 10 is pressed in.

[0071] Furthermore, the axial length C from the outer side end of the core wire 11 to the inner side end of the ventilation groove 111c is formed to be less than half the axial length D from the outer side end of the core wire 11 to the inner side end of the sealing member 13, so that a large axial length can be secured between the outer peripheral contact surface 111a located on the inner side of the ventilation groove 111c and the inner side outer peripheral surface 111b to which the pressure contact portion 121a of the elastic member 12 is joined.

[0072] This sufficiently reduces the increase in internal pressure when the inner sealing device 10 is pressed in, and increases the degree of sealing within the annular space S after pressing in, thereby preventing foreign matter such as muddy water from entering the annular space S and preventing grease within the annular space S from leaking out of the wheel bearing device 1.

[0073] Moreover, the depth d of the ventilation groove 111c may be large enough to allow air in the annular space S to be discharged to the outside when the inner sealing device 10 is press-fitted between the outer ring 2 and the inner ring 4, and may be formed to be, for example, about several μm to 100 μm. Furthermore, the cross-sectional shape of the ventilation groove 111c as viewed from the axial direction may be any shape as long as air can pass through the ventilation groove 111c when the inner sealing device 10 is press-fitted.

[0074] In addition, the ventilation groove 111c may be formed at one location on the outer peripheral contact surface 111a, but by forming the ventilation groove 111c at multiple locations in the circumferential direction on the outer peripheral contact surface 111a, the air in the annular space S can be efficiently discharged to the outside when the inner side sealing device 10 is pressed in.

[0075] When the ventilation grooves 111c are formed at a plurality of positions in the circumferential direction on the outer peripheral contact surface 111a, the ventilation grooves 111c are preferably formed at positions where the intervals between the ventilation grooves 111c are equal in the circumferential direction of the outer peripheral contact surface 111a. By arranging the plurality of ventilation grooves 111c at equal intervals in the circumferential direction in this manner, it becomes possible to reduce the pressure rise in the annular space S evenly in the circumferential direction of the inner sealing device 10 when the inner sealing device 10 is press-fitted.

[0076] Furthermore, since the ventilation groove 111c is formed on the outer peripheral contact surface 111a of the inner fitting portion 111 of the core bar 11, by forming a protrusion corresponding to the ventilation groove 111c in the portion of the die for molding the core bar 11 that forms the outer peripheral contact surface 111a, the ventilation groove 111c can be formed at the same time as the core bar 11 is press-processed using the die.

[0077] As a result, the core bar 11 having the ventilation groove 111c can be formed by the same processing steps as when the ventilation groove 111c is not formed on the outer peripheral contact surface 111a, and it is possible to suppress the pressure increase in the annular space S without increasing the cost of the inner side sealing device 10.

[0078] In addition, since the inner sealing device 10 is attached to the wheel bearing device 1 last during the assembly process of the wheel bearing device 1 to seal the annular space S, it can cause an increase in the internal pressure of the annular space S. However, by forming an air vent groove 111c in the core metal 11 of the inner sealing device 10, it is possible to exhaust air from within the annular space S to the outside through the air vent groove 111c, and therefore it is possible to effectively alleviate the increase in internal pressure of the annular space S.

[0079] In this embodiment, the inner-side sealing device 10 having the ventilation groove 111c on the outer peripheral contact surface 111a of the core wire 11 is used as a sealing member that seals the opening end on the inner side of the annular space S, but it can also be used as a sealing member that seals the opening end on the outer side of the annular space S.

[0080] In addition, the wheel bearing device 1 in this embodiment is configured as a wheel bearing device 1 of a third generation structure in which the inner raceway surface 3c is formed directly on the outer periphery of the hub wheel 3, but this is not limited to this and may be a second generation structure in which a pair of inner rings 4 are press-fitted into the hub wheel 3.

[0081] Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments, which are merely illustrative, and it goes without saying that the present invention can be embodied in various other forms without departing from the gist 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]

[0082] 1 Wheel bearing device 2 Outer ring 2a Inner side opening 2b Outer side opening 2c (inner side) outer raceway 2d (Outer side) outer raceway 3 Hub wheel 3a Small diameter stepped section 3c Inner raceway surface 4. Inner Circle 4a Inner raceway surface 5 Inner ball row 6 Outer ball row 9 Outer seal material 10 Inner sealing device 11 Core wire 12 Elastic member 13 Sealing material 14 Slinger 15 Magnetic Encoder 111 Inner fitting part 111a Outer contact surface 111c Ventilation groove 112 Side plate part 141 External fitting part 142 Circular A (vent groove) axial length B Axial length (of the peripheral contact surface) C Axial length (from the outer end of the core to the inner end of the ventilation groove) D Axial length (from the outer end of the core to the inner end of the seal material) d (Depth of vent) t (thickness of inner fitting)

Claims

1. an outer member having a double row outer raceway surface on an inner periphery thereof; an inner member including a hub wheel having an axially extending small diameter step on an outer periphery thereof and at least one inner ring press-fitted into the small diameter step of the hub wheel, the inner member having a double row inner raceway surface facing the double row outer raceway surfaces; a double row of rolling elements rollably accommodated between the raceway surfaces of the outer member and the inner member; a sealing device that closes an opening end on one axial end side of an annular space formed by the outer member and the inner member, or an opening end on the other axial end side of the annular space, The sealing device is a core metal having an inner fitting portion that is fitted to an inner periphery of the outer member and a side plate portion that extends from the inner fitting portion toward an inner diameter side, and a seal member having an elastic member that is joined to the core metal; a slinger extending from an outer fitting portion that is fitted onto an outer periphery of the inner member to an outer diameter side, the inner fitting portion has an outer peripheral contact surface that contacts an inner peripheral surface of the outer member, and an air vent groove that is formed on the outer peripheral contact surface and extends axially outward from an axially inner end of the outer peripheral contact surface, an axial length A of the ventilation groove and an axial length B of the outer circumferential contact surface have a relationship of A<B, A wheel bearing device in which an axial length C from the axial inner end of the core metal to the axial outer end of the ventilation groove and an axial length D from the axial inner end of the core metal to the axial outer end of the sealing member have the relationship C < (D / 2).

2. 2. The wheel bearing device according to claim 1, wherein an axial length A of the ventilation groove and an axial length B of the outer circumferential contact surface have a relationship of A ≥ (B / 2).

3. 3. The wheel bearing device according to claim 1, wherein a depth d of the ventilation groove and a thickness t of the inner fitting portion in a radial direction have a relationship of d≦(t / 2).

4. 3. The wheel bearing device according to claim 1, wherein the ventilation groove is formed at a plurality of positions in the circumferential direction on the outer circumferential contact surface of the inner fitting portion.

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