Bearing device for wheel

Abstract

The utility model provides a bearing device for a wheel, which can keep the contact surface pressure of a sealing lip relative to a sealing seat part in a lower state and improve the sealing property and durability of a sealing device. The step portion (3h) of the hub flange (3b) has a flange-side straight portion (3ha) extending linearly in the axial direction at the end portion on the seal seat portion (3d) side and connected to the outer diameter-side end of the seal seat portion (3d), and the outer ring (2) has an outer-side opening portion (2b) and an outer-ring-side straight portion (2ha) extending linearly from the inner diameter-side end of the outer-side end surface (2g) of the outer ring (2) toward the outer-side opening portion (2b). The boundary (P) between the step section (3h) and the seal seat section (3d) is positioned further toward the outer diameter side than an outer-side opening (2b) of the outer ring (2) and further toward the inner side than an outer-side end surface (2g) of the outer ring (2), and the flange-side straight section (3ha) and the outer-ring-side straight section (2ha) are disposed parallel to each other and at least partially overlap each other when viewed from the radial direction.

Description

Technical Field

[0001] The utility model relates to a bearing device for a wheel. Background Art

[0002] In the past, a wheel bearing device for rotatably supporting a wheel in a suspension device of a motor vehicle etc. is known. The wheel bearing device is provided with a sealing device for sealing the open end of an annular space formed by an outer member and an inner member to prevent the entry of foreign matter such as muddy water.

[0003] The sealing device, for example, has a core metal embedded in the inner circumference of an outer ring serving as an outer member, and a sealing component integrally joined to the core metal and having a plurality of sealing lips. The hub ring serving as an inner member has a hub flange extending toward the outer diameter side, and a sealing seat portion formed at the base of the hub flange and contacted by the sealing lips of the sealing component.

[0004] Thus, in a wheel bearing device having a sealing device with a structure in which a sealing lip contacts a sealing seat portion of a hub ring, the following processing is performed: a step portion is formed between the sealing seat portion and the side surface of the hub flange, an annular recessed portion radially opposite to the step portion is formed on the inner periphery of the outer ring, and a labyrinth seal is formed between the step portion of the hub ring and the recessed portion of the outer ring (see patent document 1).

[0005] By forming a labyrinth seal between the hub ring and the outer ring, muddy water from the outside can be prevented from directly penetrating into the sealing device, thereby improving the sealing performance and durability of the sealing device.

[0006] In addition, the sealing performance of the sealing device can be improved by increasing the contact surface pressure of the sealing lip with respect to the sealing seat in the sealing device.

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent Application Publication No. 2009-150437 Utility Model Content

[0010] Issues to be solved by utility models

[0011] However, in recent years, with the advancement of vehicle electrification, there has been an increasing demand for lower torque in wheel bearing devices, and therefore the contact surface pressure of the seal lip with respect to the seal seat portion, which affects the rotational torque of the wheel bearing device, is preferably lowered.

[0012] The utility model is completed in view of the above-mentioned situation, and provides a wheel bearing device which can further suppress the infiltration of foreign matter such as mud and water into the sealing device by setting the shape of the labyrinth formed between the step portion of the hub ring and the recessed portion of the outer ring to an appropriate shape, and can maintain the contact surface pressure of the sealing lip relative to the sealing seat portion at a low state, thereby improving the sealing performance and durability of the sealing device.

[0013] Solutions to Solve Problems

[0014] The wheel bearing device comprises: an outer member having a double row of outer raceway surfaces on its inner circumference; an inner member consisting of a hub ring and a raceway surface forming member, the hub ring having an inner raceway surface on its outer circumference that is opposite to the outer raceway surface and a hub flange for mounting a wheel, the raceway surface forming member being connected to the hub ring, and the raceway surface forming member having an inner raceway surface on its outer circumference that is opposite to the outer raceway surface; double rows of rolling elements that are freely accommodated between the two raceway surfaces of the outer member and the inner member; and a sealing device that is embedded in the outer member and seals an open end on one axial end side of the annular space formed by the outer member and the inner member, wherein the hub ring has a sealing seat portion for contact with the sealing device, a sealing portion on the hub flange that is closer to the outer raceway surface than the outer raceway surface. The flange side surface of the seal seat portion is located on the axial side of the seal seat portion at the outer diameter side, and a step portion connecting the seal seat portion and the flange side surface, the step portion having a flange side straight line portion extending linearly in the axial direction and connected to the outer diameter side end of the seal seat portion at the end portion on the seal seat portion side, the outer member having a fitting portion for the sealing device to fit, and an outer member side straight line portion extending linearly from the inner diameter side end of one axial end face of the outer member toward one side of the fitting portion, the boundary between the step portion and the seal seat portion being located on the outer diameter side of the fitting portion of the outer member and on the other axial side of the one axial end face of the outer member, the flange side straight line portion being arranged in parallel with the outer member side straight line portion and at least partially overlapping when viewed in the radial direction.

[0015] Utility Model Effect

[0016] According to the utility model, the contact surface pressure of the sealing lip with respect to the sealing seat portion can be maintained at a low state, and the sealing performance and durability of the sealing device can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a side sectional view showing the wheel bearing device.

[0018] Figure 2It is a side cross-sectional view showing the outer side end portion of the outer ring to which the outer side sealing member is fitted and the hub flange of the hub ring.

[0019] Figure 3 It is a side cross-sectional view showing a labyrinth seal formed by the recessed portion of the outer ring, the stepped portion of the hub flange, and the seal seat portion.

[0020] Figure 4 It is a side cross-sectional view showing a seal seat portion of a hub wheel and an outer end surface of an outer ring according to a second embodiment.

[0021] Figure 5 It is a side sectional view showing a wheel bearing device of a fourth generation structure.

[0022] Description of Reference Numerals

[0023] 1Wheel bearing device

[0024] 2 Outer ring

[0025] 2b External opening

[0026] 2c (Inner side) Outer track surface

[0027] 2d (outer side) outer track surface

[0028] 2g External side surface

[0029] 2h concave part

[0030] 2ha outer ring side straight part

[0031] 3 wheel hub

[0032] 3b wheel hub flange

[0033] 3c inner track surface

[0034] 3d seal seat

[0035] 3g flange side

[0036] 3h step section

[0037] 3ha flange side straight part

[0038] 4Inner circle

[0039] 4a Inner track surface

[0040] 5 internal side ball rows

[0041] 6 external side ball rows

[0042] 10 External side sealing member

[0043] cA The second arc

[0044] cB first arc

[0045] hStep height

[0046] mA (length of the second arc)

[0047] mB (length of the first arc)

[0048] rA (radius of the second arc)

[0049] rB (radius of the first arc)

[0050] IP intersection

[0051] P (Boundary between step and seal seat)

[0052] Q (boundary between the outer end surface of the outer ring and the concave portion)

[0053] S Ring Space

[0054] SP Span Center

[0055] LC span centerline

[0056] X rotation axis. DETAILED DESCRIPTION

[0057] Hereinafter, embodiments for carrying out the present invention will be described using the drawings.

[0058] [Wheel bearing device]

[0059] Figure 1 The wheel bearing device 1 shown is one embodiment of the wheel bearing device of the present invention, and is used to rotatably support a wheel in a suspension device of a vehicle such as an automobile.

[0060] In the following description, the axial direction indicates a direction along the rotation axis X of the wheel bearing device 1 .

[0061] The outer side refers to one axial side and the wheel side of the wheel bearing device 1 when mounted on a vehicle body, and the inner side refers to the other axial side and the vehicle body side of the wheel bearing device 1 when mounted on a vehicle body.

[0062] The wheel bearing device 1 has a structure called the third generation, and includes an outer ring 2 as an outer member, a hub ring 3 and an inner ring 4 as inner members, an inner side ball row 5 and an outer side ball row 6 of double rows as rolling rows, an inner side sealing member 9, and an outer side sealing member 10. The inner ring 4 is an example of a raceway surface forming member connected to the hub ring.

[0063] An inner opening 2a into which the inner sealing member 9 can be fitted is formed at the inner end of the outer ring 2. An outer opening 2b into which the outer sealing member 10 can be fitted is formed at the outer end of the outer ring 2.

[0064] The inner sealing member 9 is fitted into the inner opening 2a to seal the inner opening end of the annular space S formed by the outer ring 2 and the inner member. The outer sealing member 10 is fitted into the outer opening 2b to seal the outer opening end of the annular space S.

[0065] The inner side sealing member 9 and the outer side sealing member 10 are sealing devices that seal the open end of the annular space S formed by the outer ring 2 as the outer member and the inner member. In this way, by using the inner side sealing member 9 and the outer side sealing member 10 to seal the inner and outer opening ends of the annular space S, a sealing function is exerted to suppress the infiltration of foreign matter such as muddy water into the wheel bearing device 1.

[0066] An inner outer raceway surface 2c and an outer outer raceway surface 2d are formed on the inner circumferential surface of the outer ring 2. A vehicle body mounting flange 2e for mounting the outer ring 2 to a vehicle body side member (steering knuckle) is integrally formed on the outer circumferential surface of the outer ring 2. Bolt holes 2f are provided in the vehicle body mounting flange 2e for inserting a fastening member for fastening and connecting the vehicle body side member to the outer ring 2.

[0067] A small-diameter stepped portion 3a having a smaller diameter than the outer side end is formed at the inner side end of the outer peripheral surface of the hub ring 3. A hub flange 3b for mounting a wheel is integrally formed at the outer side end of the hub ring 3. Bolt holes 3f for pressing hub bolts 3i are provided in the hub flange 3b. The hub ring 3 has a through hole 3e that penetrates in the axial direction.

[0068] An inner track surface 3c on the outer side is provided on the outer peripheral surface of the hub ring 3 in a manner opposite to the outer track surface 2d on the outer side of the outer ring 2. The inner track surface 3c is an example of an inner track surface on the side facing the outer track surface. In addition, in the hub ring 3, a seal seat portion 3d for the outer side sealing member 10 to contact is formed at the base of the hub flange 3b.

[0069] The hub flange 3b has a flange side surface 3g facing the inner side. The flange side surface 3g is located on the outer diameter side of the seal seat portion 3d in the radial direction and is located on the outer side of the seal seat portion 3d in the axial direction. That is, the flange side surface 3g is located on the outer diameter side of the hub flange 3b than the seal seat portion 3d and is located on the outer side of the seal seat portion 3d.

[0070] A step portion 3h is formed between the flange side surface 3g and the seal seat portion 3d. The step portion 3h connects the flange side surface 3g and the seal seat portion 3d. The step portion 3h is curved inwardly as it approaches the inner diameter side and is formed in an arc shape that is convex toward the inner diameter side.

[0071] The inner ring 4 is provided on the small diameter step portion 3a of the hub ring 3. An inner raceway surface 4a is provided on the outer peripheral surface of the inner ring 4 so as to face the outer raceway surface 2c on the inner side of the outer ring 2. The inner raceway surface 4a is an example of the other inner raceway surface facing the outer raceway surface.

[0072] The inner ball row 5 and the outer ball row 6 as rolling rows are formed by a plurality of balls 7 as rolling bodies being held by a retainer 8. The inner ball row 5 is freely rollably sandwiched between the inner raceway surface 4a of the inner ring 4 and the outer raceway surface 2c on the inner side of the outer ring 2. The outer ball row 6 is freely rollably sandwiched between the inner raceway surface 3c of the hub ring 3 and the outer raceway surface 2d on the outer side of the outer ring 2.

[0073] In the wheel bearing device 1, a double row angular contact ball bearing is formed by the outer ring 2, the hub ring 3, the inner ring 4, the inner ball row 5 and the outer ball row 6. However, the wheel bearing device 1 may be formed by a double row tapered roller bearing.

[0074] The balls 7 in the inner ball row 5 contact the inner ring 4 at the contact point 41, and the contact angle of the balls 7 in the inner ball row 5 relative to the inner ring 4 is α. The balls 7 in the outer ball row 6 contact the hub ring 3 at the contact point 31, and the contact angle of the balls 7 in the outer ball row 6 relative to the hub ring 3 is β.

[0075] A straight line L1 passing through the center C1 of the ball 7 in the inner ball row 5 and the contact point 41 and a straight line L2 passing through the center C2 of the ball 7 in the outer ball row 6 and the contact point 31 intersect at the span center SP.

[0076] The span center SP is the span center of the balls 7 in the inner ball row 5 and the balls 7 in the outer ball row 6. A span center line LC passing through the span center SP and extending in a direction perpendicular to the axial direction intersects the rotation axis X at an intersection IP.

[0077] [External side sealing member]

[0078] like Figure 2 As shown, the outer sealing member 10 includes a metal core 11 fitted into the inner periphery of the outer end portion of the outer ring 2 , and a sealing member 12 integrally joined to the metal core 11 .

[0079] The core metal 11 is made of, for example, a steel plate, and includes a cylindrical fitting portion 111 fitted to the inner periphery of the outer opening 2 b of the outer ring 2 , and an inner portion 112 extending radially inward from the outer end of the fitting portion 111 .

[0080] The sealing member 12 is formed of an elastic member such as synthetic rubber, and is bonded to the core metal 11 by vulcanization bonding. The sealing member 12 includes a grease lip 12a, a first side lip 12b, and a second side lip 12c.

[0081] The grease lip 12 a extends from the inner portion 112 of the core metal 11 toward the inner diameter side and the inner side, and contacts the seal seat portion 3 d .

[0082] The first side lip 12b extends from the inner side portion 112 of the core metal 11 toward the outer side and the outer diameter side of the hub flange 3b on the outer diameter side of the grease lip 12a. The first side lip 12b contacts the seal seat portion 3d.

[0083] The second side lip 12c extends from the inner side portion 112 of the core metal 11 toward the outer side and the outer diameter side of the hub flange 3b on the outer diameter side of the first side lip 12b. The second side lip 12c contacts the seal seat portion 3d.

[0084] The grease lip 12a, the first side lip 12b, and the second side lip 12c are seal lips included in the seal member 12 and are contact lips that come into contact with the seal seat portion 3d. The second side lip 12c is a seal lip located on the outermost diameter side in the seal member 12.

[0085] [Structure of the hub flange and the outer end portion of the outer ring]

[0086] like Figure 2 , Figure 3 As shown, the outer diameter side end of the seal seat portion 3d and the inner side end of the step portion 3h are connected at the boundary P. The chamfered portion 3da is formed at the outer diameter side end of the seal seat portion 3d. The outer diameter side end of the chamfered portion 3da forms the boundary P in the seal seat portion 3d.

[0087] The step portion 3h has a flange side straight portion 3ha at the end portion on the inner side of the end portion on the seal seat portion 3d side, and the flange side straight portion 3ha extends linearly along the axial direction orthogonal to the circumferential direction of the hub wheel 3 and is connected to the boundary P located at the outer diameter side end of the seal seat portion 3d. In the present embodiment, the flange side straight portion 3ha is formed parallel to the rotation axis X. The flange side straight portion 3ha may also be formed along the axial direction having an inclination angle relative to the rotation axis X.

[0088] The outer ring 2 has an annular recess 2h formed by cutting away the inner circumferential surface at the outer end of the outer ring 2. The recess 2h is located between the outer end surface 2g and the outer opening 2b of the outer ring 2. The outer opening 2b is an example of a fitting portion into which a sealing device is fitted.

[0089] The inner diameter side end of the outer end face 2g of the outer ring 2 is connected to the outer end of the recess 2h at the boundary Q. A chamfered portion 2ga is formed at the inner diameter side end of the outer end face 2g. The inner diameter side end of the chamfered portion 2ga forms the boundary Q in the outer end face 2g.

[0090] The recessed portion 2h has an outer ring side straight portion 2ha, which is perpendicular to the circumferential direction of the hub ring 3 and extends linearly from the boundary Q of the inner diameter side end of the outer side end face 2g to the inner side of the side facing the outer side opening 2b. The outer ring side straight portion 2ha is an example of a straight portion on the outer member side. The outer ring side straight portion 2ha is opposite to the flange side straight portion 3ha in the radial direction. In the present embodiment, the outer ring side straight portion 2ha is formed parallel to the rotation axis X. The outer ring side straight portion 2ha can also be formed along an axial direction having an inclination angle relative to the rotation axis X.

[0091] The boundary P between the step portion 3h and the seal seat portion 3d is located radially on the outer diameter side of the outer opening portion 2b of the outer ring 2, and axially on the inner side of the outer end face 2g of the outer ring 2. The boundary P between the step portion 3h and the seal seat portion 3d is located on the inner diameter side of the outer ring side straight portion 2ha.

[0092] The flange side straight portion 3ha is located at a position closer to the inner diameter side than the outer ring side straight portion 2ha. The end portion of the flange side straight portion 3ha on the side where at least the boundary P is located, that is, the inner end portion, is located at a position closer to the outer diameter side than the outer side opening 2b of the outer ring 2. In the present embodiment, the entire flange side straight portion 3ha is located at a position closer to the outer diameter side than the outer side opening 2b of the outer ring 2.

[0093] The flange side straight portion 3ha and the outer ring side straight portion 2ha are arranged in parallel in a direction orthogonal to the circumferential direction of the hub ring 3. In the present embodiment, the flange side straight portion 3ha and the outer ring side straight portion 2ha are arranged in parallel with the axial direction (the direction of the rotation axis X). The flange side straight portion 3ha and the outer ring side straight portion 2ha can also be formed along the axial direction with an inclination angle relative to the rotation axis X and arranged in parallel.

[0094] The flange side straight portion 3ha overlaps with the outer ring side straight portion 2ha when viewed from the radial direction. In the present embodiment, the outer ring side straight portion 2ha is set longer than the flange side straight portion 3ha. The flange side straight portion 3ha and the outer ring side straight portion 2ha may overlap at least partially when viewed from the radial direction.

[0095] In the wheel bearing device 1 , a labyrinth seal LS is formed by the recessed portion 2 h formed at the outer end of the outer ring 2 , the stepped portion 3 h formed at the hub flange 3 b of the hub wheel 3 , and the seal seat portion 3 d .

[0096] By forming the labyrinth seal LS between the hub wheel 3 and the outer wheel 2 in this manner, it is possible to suppress foreign matter such as muddy water from the outside from directly entering the outer side sealing member 10 by the labyrinth seal LS.

[0097] Furthermore, even if foreign matter such as muddy water infiltrates into the outer sealing member 10 , the momentum of the infiltrating foreign matter such as muddy water is reduced by the labyrinth seal LS, so that the impact on the seal lip of the sealing member 12 can be reduced.

[0098] This can improve the sealing performance and durability of the outer seal member 10 , and can extend the life of the wheel bearing device 1 as a whole.

[0099] Furthermore, even if the contact surface pressure of the sealing lip in the outer side sealing component 10 relative to the sealing seat portion 3d is set to be smaller, the sealing performance of the outer side sealing component 10 can be maintained, thereby reducing the rotational torque of the wheel bearing device 1 and improving the fuel consumption and power consumption of the vehicle equipped with the wheel bearing device 1.

[0100] In this case, a boundary P between the step portion 3h and the seal seat portion 3d is located radially outward of the outer opening 2b of the outer ring 2 and inward of the outer end surface 2g of the outer ring 2 .

[0101] Therefore, the labyrinth seal LS is formed across the portion where the step portion 3h of the hub flange 3b faces the recessed portion 2h of the outer ring 2 and the portion where the seal seat portion 3d of the hub flange 3b faces the recessed portion 2h of the outer ring 2, thereby ensuring that the length of the labyrinth seal LS is relatively large.

[0102] This can further improve the sealing performance of the outer sealing member 10 , keep the contact surface pressure of the seal lip of the outer sealing member 10 against the seal seat portion 3 d low, and improve the sealing performance and durability of the outer sealing member 10 .

[0103] In addition, the flange side straight portion 3ha and the outer ring side straight portion 2ha are arranged parallel to each other and overlap when viewed from the radial direction. Therefore, there is a portion in the labyrinth seal LS where the size of the gap between the hub ring 3 and the outer ring 2 is constant, which can stably exhibit foreign matter resistance performance.

[0104] In addition, the flange side straight portion 3ha and the outer ring side straight portion 2ha are both arranged parallel to the rotation axis X of the hub ring 3, so the labyrinth seal LS can effectively weaken the momentum of foreign matter such as mud and water flowing from the top of the hub flange 3b along the flange side surface 3g and the step portion 3h.

[0105] In addition, if Figure 2 , Figure 3 As shown, the axial length D1 from the outer end surface 2g of the outer ring 2 to the boundary P between the step portion 3h and the seal seat portion 3d is set to be 0.5 mm or more and 5 mm or less.

[0106] By setting the axial length D1 to be greater than 0.5 mm, the foreign matter resistance performance of the labyrinth seal LS formed between the hub ring 3 and the outer ring 2 can be effectively exerted. In addition, by setting the axial length D1 to be less than 5 mm, the axial length of the labyrinth seal LS can be prevented from being too large, thereby suppressing the axial enlargement of the wheel bearing device 1.

[0107] Furthermore, when the axial length D1 increases and the outer side end face 2g of the outer ring 2 protrudes too much toward the hub flange 3b, it is necessary to reduce the radius of the arc shape in the step portion 3h of the hub flange 3b opposite to the outer side end face 2g, which may cause stress concentration in the step portion 3h.

[0108] However, by setting the axial length D1 to 5 mm or less, the outer end surface 2g does not protrude too much toward the hub flange 3b, and the radius of the arc shape in the step portion 3h can be set larger, thereby suppressing stress concentration in the step portion 3h.

[0109] In addition, if Figure 3 As shown in the figure, the axial length D2 of the overlapping portion of the flange side straight portion 3ha and the outer ring side straight portion 2ha when viewed from the radial direction is set to be greater than 1 mm. By setting the axial length D2 to be greater than 1 mm, the length of the portion where the size of the gap between the hub ring 3 and the outer ring 2 in the labyrinth seal LS is constant can be ensured, and the foreign matter resistance performance can be more stably exerted.

[0110] In addition, if Figure 3 As shown, the radial separation distance D3 between the flange-side straight portion 3ha and the outer ring-side straight portion 2ha is set to be greater than or equal to 0.4 mm and less than or equal to 0.6 mm.

[0111] By setting the separation distance D3 to be greater than 0.4 mm, a gap between the outer ring 2 and the hub ring 3 where the labyrinth seal LS is formed is ensured. Even when a rotational load is applied to the wheel bearing device 1 and the hub ring 3 is tilted relative to the outer ring 2, interference between the hub ring 3 and the outer ring 2 can be suppressed.

[0112] Furthermore, by setting the separation distance D3 to be 0.6 mm or less, it is possible to prevent the gap between the hub wheel 3 and the outer wheel 2 from becoming excessively large, and to ensure the foreign matter resistance performance of the labyrinth seal LS.

[0113] like Figure 1 to Figure 3 As shown in the figure, the radius of the first arc cB, which is centered at the intersection IP of the span center line LC and the rotation axis X and passes through the boundary P between the step portion 3h and the seal seat portion 3d, is rB. In addition, the length of the first arc cB from the boundary P between the step portion 3h and the seal seat portion 3d to the inner circumference of the recessed portion 2h of the outer ring 2 is mB.

[0114] The radius of the second arc cA, which is centered at the intersection IP of the span centerline LC and the rotation axis X and passes through the boundary Q at the inner diameter side end of the outer side end face 2g of the outer ring 2, is rA. In addition, the length of the second arc cA from the boundary Q at the inner diameter side end of the outer side end face 2g of the outer ring 2 to the step portion 3h of the hub ring 3 is mA.

[0115] In the labyrinth seal LS formed between the outer ring 2 and the hub ring 3, the boundary Q at the inner diameter side end of the outer side end face 2g of the outer ring 2 is located on the outer side of the wheel bearing device 1 where foreign matter such as mud and water penetrates, and the boundary P between the step portion 3h and the sealing seat portion 3d is located on the inner side of the wheel bearing device 1 where foreign matter such as mud and water penetrates and leaks toward the outer side sealing component 10.

[0116] The length mB of the first arc cB and the length mA of the second arc cA satisfy the relationship mA≤mB.

[0117] In this way, by satisfying the relationship of mA≤mB between the length mB and the length mA, the gap on the outer side of the boundary Q of the labyrinth seal LS formed between the outer ring 2 and the hub ring 3 can be made smaller than the gap on the inner side of the boundary P. It is more preferable that the above relationship is satisfied when no rotational load is applied to the wheel bearing device 1.

[0118] Thus, when no rotation load is applied to the wheel bearing device 1 , the gap on the outer side of the entrance portion of the labyrinth seal LS, which is a place where foreign matter such as muddy water enters, can be kept at a minimum, thereby further improving foreign matter resistance performance.

[0119] When a rotation load is applied to the wheel bearing device 1 , the radius rB of the first arc cB, the length mB of the first arc cB, the radius rA of the second arc cA, and the length mA of the second arc cA satisfy the relationship (mA / rA)≤(mB / rB).

[0120] In this way, by satisfying the relationship of (mA / rA)≤(mB / rB) among the radius rB, length mB, radius rA and length mA, even when the wheel bearing device 1 is loaded with a rotational load and the hub ring 3 is tilted relative to the outer ring 2, a sufficient relationship between the outer side gap (length mA) and the inner side gap (length mB) can be maintained to maintain the function of the labyrinth seal LS, and mud and water resistance can be ensured.

[0121] [Second Embodiment of the Seal Seat Portion of the Hub Ring and the Outer End Surface of the Outer Ring]

[0122] The seal seat portion 3d of the hub ring 3 and the outer end surface 2g of the outer ring 2 can also be formed as Figure 4 The seal seat portion 3dA and the outer end surface 2gA are shown.

[0123] The seal seat portion 3dA is different from the seal seat portion 3d in that it does not include the chamfered portion 3da. The outer end surface 2gA is different from the outer end surface 2g in that it does not include the chamfered portion 2ga.

[0124] In this way, in the structure in which a sealing seat portion 3dA without a chamfered portion and an outer side end face 2gA are formed, a labyrinth seal LS can be formed by utilizing the recessed portion 2h formed on the outer side end portion of the outer ring 2 and the stepped portion 3h formed on the hub flange 3b of the hub ring 3 and the sealing seat portion 3dA, in the same manner as in the structure in which a sealing seat portion 3d with a chamfered portion 3da and an outer side end face 2g with a chamfered portion 2ga are formed.

[0125] Through the labyrinth seal LS formed by the recessed portion 2h of the outer ring 2, the stepped portion 3h of the hub ring 3, and the seal seat portion 3dA, the contact surface pressure of the seal lip in the outer side seal component 10 relative to the seal seat portion 3d can be maintained at a low state, thereby improving the sealing and durability of the outer side seal component 10.

[0126] It should be noted that the wheel bearing device 1 in the present embodiment is a third-generation structure in which an inner raceway surface 3c is directly formed on the outer periphery of the hub ring 3, but is not limited to this. It may also be a second-generation structure in which a pair of inner rings 4 are pressed and fixed to the hub ring 3.

[0127] In addition, the wheel bearing device 1 can also be configured to have a fourth generation structure without the inner ring 4 by forming the inner raceway surface opposite to the outer raceway surface 2c of the outer ring 2 on the inner ring 4 and forming it on a constant velocity joint engaged with the through hole 3e of the hub ring 3. In this case, the constant velocity joint becomes a raceway surface forming member connected to the hub ring.

[0128] The wheel bearing device of the fourth generation structure which does not include the inner ring 4 can be configured as follows, for example. Figure 5 The wheel bearing device 1A shown in FIG. 1A includes a constant velocity joint 50 connected to the hub wheel 3A, and does not include the inner ring 4. The constant velocity joint 50 is an example of a raceway surface forming member connected to the hub wheel.

[0129] The constant velocity joint 50 includes a mouth portion 52 for supporting a shaft to which a driving force is input from a driving source, and a rod portion 53 extending outward from the mouth portion 52. The hub wheel 3A has a through hole 3e extending in the axial direction, and the through hole 3e and the rod portion 53 are spline-fitted.

[0130] An inner raceway surface 58 is formed on the outer peripheral surface of the outer end portion of the mouth 52, which faces the outer raceway surface 2c on the inner side of the outer ring 2. The inner raceway surface 58 is an example of the inner raceway surface on the other side facing the outer raceway surface. The inner ball row 5 is freely sandwiched between the outer raceway surface 2c on the inner side of the outer ring 2 and the inner raceway surface 58 of the mouth 52 in the constant velocity universal joint 50.

[0131] That is, in the wheel bearing device 1A, the constant velocity joint 50 having the inner raceway surface 58 facing the outer raceway surface 2 c of the outer race 2 is configured to also serve as the inner race.

[0132] The embodiments of the present invention are described above, but the present invention is not limited to such embodiments, but is merely exemplified. Of course, it can be further implemented in various ways within the scope of the main purpose of the present invention. The scope of the present invention is shown by the records of the patent technical solution, and also includes the equivalent meanings recorded in the patent technical solution and all changes within the scope.

Claims

1. A wheel bearing device, comprising: An outer member having a double row of outer track surfaces on the inner periphery; an inner member, which is composed of a hub ring and a raceway forming member, the hub ring having an inner raceway surface on one side facing the outer raceway surface and a hub flange for mounting a wheel, the raceway forming member being connected to the hub ring and having an inner raceway surface on the other side facing the outer raceway surface on the outer periphery; Double rows of rolling elements, which are freely accommodated between the two track surfaces of the outer member and the inner member; and a sealing device which is fitted in the outer member and seals an opening end on one axial end side of the annular space formed by the outer member and the inner member, in, The hub wheel has a seal seat portion for the seal device to contact, a flange side surface of the hub flange located on the outer diameter side of the seal seat portion and on the axial side of the seal seat portion, and a step portion connecting the seal seat portion and the flange side surface. The step portion has a flange side straight portion at an end portion on the seal seat side that extends straightly in the axial direction and is connected to the outer diameter side end of the seal seat. The outer member has a fitting portion in which the sealing device is fitted, and an outer member side straight portion extending linearly from an inner diameter side end of one axial end surface of the outer member toward a side of the fitting portion. The boundary between the step portion and the seal seat portion is located on the outer diameter side of the fitting portion of the outer member and on the other axial side of the axial end surface of the outer member. The flange-side straight portion and the outer-member-side straight portion are arranged in parallel and at least partially overlap each other when viewed in the radial direction.

2. The wheel bearing device according to claim 1, wherein: The flange-side straight portion and the outer member-side straight portion are parallel to the rotation axis of the hub wheel.

3. The wheel bearing device according to claim 1 or 2, wherein: An axial length from the one axial end surface of the outer member to the boundary between the step portion and the seal seat portion is not less than 0.5 mm and not more than 5 mm.

4. The wheel bearing device according to claim 1 or 2, wherein: The axial length of a portion where the flange-side straight portion and the outer-member-side straight portion overlap each other when viewed in the radial direction is 1 mm or more.

5. The wheel bearing device according to claim 1 or 2, wherein: A radial separation distance between the flange-side straight portion and the outer-member-side straight portion is greater than or equal to 0.4 mm and less than or equal to 0.6 mm.

6. The wheel bearing device according to claim 1 or 2, wherein: The arc having the intersection of the span center line and the rotation axis of the hub ring as the center and passing through the boundary between the step portion and the seal seat portion is set as the first arc, and the span center line passes through the span center of the rolling element on one axial side and the rolling element on the other axial side and extends in a direction orthogonal to the axial direction. The arc having the intersection of the span center line and the rotation axis as the center and passing through the inner diameter side end of the axial end surface of the outer member is set as the second arc. The length mB of the first arc from the boundary between the step portion and the seal seat portion to the inner circumferential surface of the outer member and the length mA of the second arc from the inner diameter side end of the axial end surface of the outer member to the step portion of the hub ring satisfy the following relationship: mA≤mB.

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