Bearing device for wheel

Abstract

To reduce stress concentration in a hub wheel while securing sealing performance of a sealing device in a bearing device for a wheel.SOLUTION: The radius r of curvature of the stepped portion side 3i, the axial length h of the first boundary side 3i at the boundary between the radially inner end of the stepped portion side 3g and the radially outer end of the seal land portion side P1, and the axial length h of the second boundary side 3i at the boundary between the radially outer end of the stepped portion side 3b and the radially inner end of the flange side P2 of the axle mounting flange 3f, At least one of a relationship of 0.04 ≤ (r-h) / PCDh ≤ 0.80 and a relationship of 0.04 ≤ (P1 - d2) / (2 * PCDh * tan θ) ≤ 0.80 is satisfied, where d1 is a radius of the first boundary 3i, d2 is a radius of the second boundary, PCDh is a pitch circle radius of the hub bolt 3f, and θ is an angle of a tangent at the first boundary of the step portion wall with respect to the radial direction. d1 P2.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] 2. Description of the Related Art Wheel bearing devices that rotatably support wheels in suspension systems for automobiles and the like are known.

[0003] In recent years, fuel regulations have been imposed on vehicles that use wheel bearing devices in response to social trends such as energy conservation and decarbonization, and the trend toward electrification is progressing. Electric vehicles, which are primarily powered by on-board batteries and are expected to become more popular in the future, tend to be heavier than gasoline-powered vehicles, and their axle loads tend to increase.

[0004] Generally, as the axle load increases, the rotational torque of the wheel bearing device increases, and from the perspective of strength, the wheel bearing device needs to be enlarged. For example, in wheel bearing devices used in electric vehicles, the axial distance from the outer side surface of the wheel mounting flange of the hub wheel to the inner end of the inner ring is smaller than the outer diameter of the inner end (pilot portion) of the outer ring, and they tend to be narrow and large in diameter. In addition, the mounting dimensions of wheel bearing devices have often not changed significantly from the past, and the steel ball rows are configured to move closer in both radial and axial directions to the hub bolts that fasten the hub wheel to the wheel or brake components at the wheel mounting flange of the hub wheel. This has been addressed by thinning the wheel mounting flange of the hub wheel and reducing the dimensions of various components. However, thinning the wheel mounting flange of the hub wheel and reducing the dimensions of various components can lead to stress concentration.

[0005] Furthermore, from the viewpoint of reducing fuel consumption, there is a demand for a wheel bearing device with lower torque. To achieve this, it is conceivable to reduce the contact force of the sliding surfaces of the lip of the sealing device between the outer ring and the hub wheel, for example, but this may lead to a decrease in the sealing performance of the sealing device.

[0006] In Patent Document 1, the wheel bearing device includes double-row rolling elements rollably housed between the rolling surfaces of an inner member and an outer member via a cage, and a seal attached to the opening of an annular space formed between the outer member and the inner member, the base of the inner side of the wheel mounting flange being formed in an arc-shaped cross section, the outer seal of the seals being in sliding contact with this base, a step being formed between the side surface of the inner side of the wheel mounting flange and the base, the corners of this step being formed into arc-shaped surfaces with a predetermined radius of curvature, and annular recesses being formed in the inner periphery of the outer end of the outer member, and annular labyrinths with a generally L-shaped cross section being formed facing the corners of the step with a small gap between them. In this way, the wheel bearing device of Patent Document 1 ensures the sealing performance of the sealing device, and the labyrinth prevents foreign matter such as muddy water from entering the outer seal side. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-150437 Summary of the Invention [Problem to be solved by the invention]

[0008] However, in the wheel bearing device described above, although the labyrinth prevents the intrusion of foreign matter such as muddy water into the outer seal side while ensuring the sealing performance of the sealing device, in order to adapt it to the narrow, large-diameter wheel bearing devices of recent years, as mentioned above, it is thought that measures such as thinning the wheel mounting flange of the hub wheel and reducing the dimensions of various parts such as the radius of curvature of the stepped part of the wheel mounting flange will be necessary. And, by thinning the wheel mounting flange of the hub wheel and reducing the dimensions of various parts in this way, stress concentration can occur in the hub wheel.

[0009] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a wheel bearing device that can reduce stress concentration in a hub wheel while ensuring the sealing performance of a sealing device. [Means for solving the problem]

[0010] That is, an outer ring is an outer member having double-row outer raceway grooves on its inner periphery; an inner member including a hub ring having a small diameter stepped portion at an inner end of an outer periphery thereof, and an inner ring provided on the small diameter stepped portion of the hub ring, the inner member having double rows of inner raceway grooves facing the double rows of outer raceway grooves; an outer seal member fitted into an outer opening formed between the outer ring and the hub wheel; an inner-side ball row rollably accommodated between an outer raceway groove on an inner side of the outer ring and an inner raceway groove on the inner ring; a wheel bearing device including an outer side ball row rollably accommodated between an outer raceway groove on an outer side of the outer ring and an inner raceway groove of the hub ring, The hub wheel is a wheel mounting flange formed on an outer end of the hub wheel for mounting a wheel; a plurality of bolt holes axially passing through the wheel mounting flange; a plurality of bolts press-fitted into the plurality of bolt holes, respectively; a seal land portion formed at a base of the wheel mounting flange and contacting the outer seal member; an inner flange side surface of the wheel mounting flange; a step portion that connects the flange side surface and the seal land portion and has a cross section that is formed in an arc shape, a radially inner end of the step portion is connected to a radially outer end of the seal land portion, and a boundary portion between the radially inner end of the step portion and the radially outer end of the seal land portion is configured as a first boundary P1, a radially outer end of the step portion is connected to a radially inner end of the flange side surface, and a boundary portion between the radially outer end of the step portion and the radially inner end of the flange side surface is configured as a second boundary P2, Regarding the following conditions 1 to 5, At least one of conditions 1 and 2 is met, And condition 3 is met, Furthermore, at least one of conditions 4 and 5 must be satisfied. Condition 1: The relationship between the length a of the outer diameter of the inner end of the outer ring and the length b of the axial direction from the outer side surface of the wheel mounting flange of the hub ring to the inner side surface of the inner ring is 1.20≦a / b≦1.95 Condition 2: The pitch circle diameter PCDo of the outer ball row and the pitch circle diameter PCDh of the bolt of the hub ring satisfy the relationship: 0.60≦PCDo / PCDh≦0.73 Condition 3: The relationship d0≧d1 is satisfied between the inner diameter d0 of the portion of the outer ring at the outer end where the outer seal member is fitted and the diameter d1 of the first boundary P1. Condition 4: The relationship between the radius of curvature r of the step portion of the hub wheel, the axial length h between the first boundary P1 and the second boundary P2, and the pitch circle diameter PCDh of the bolt of the hub wheel is 0.04≦(r−h) / PCDh≦0.80 Condition 5: where d1 is the diameter of the first boundary P1, d2 is the diameter of the second boundary P2, PCDh is the pitch circle diameter of the bolt of the hub wheel, and θ is the angle of the tangent of the stepped portion of the hub wheel at the first boundary P1 with respect to the radial direction, the relationship is 0.04≦(d1−d2) / (2×PCDh×tanθ)≦0.80. [Effects of the Invention]

[0011] The present invention has the following effects. That is, according to the wheel bearing device of the present invention, it is possible to reduce stress concentration in the hub wheel while ensuring the sealing performance of the sealing device. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a cross-sectional view showing a wheel bearing device according to an embodiment of the present invention; [Figure 2] 10 is an enlarged cross-sectional view showing the structure of a wheel mounting flange of a hub wheel and an outer end portion of an outer ring of the wheel bearing device; FIG. [Figure 3] 10 is an enlarged cross-sectional view showing the structure of a wheel mounting flange of a hub wheel and an outer end portion of an outer ring of the wheel bearing device; FIG. [Figure 4] (a) A diagram showing the stress amplitude level of the step portion of the hub ring in the same wheel bearing device configured under condition 4, and (b) A diagram showing the stress amplitude level of the step portion of the hub ring in the same wheel bearing device configured under condition 5. [Figure 5] FIG. 10 is an enlarged view of the hub ring of the wheel bearing device as viewed from the inner side. [Figure 6] 10 is an enlarged cross-sectional view showing the structure of the wheel mounting flange and the outer end of the outer ring in a portion where no ribs are arranged in the hub ring of the wheel bearing device; FIG. [Figure 7] 10 is an enlarged cross-sectional view showing the structure of a wheel mounting flange of a hub wheel and an outer end portion of an outer ring of the wheel bearing device; FIG. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0014] [Wheel bearing device] A wheel bearing device 1 shown in FIG. 1 uses a sealing device according to the present invention, and supports a wheel rotatably in a suspension system of a vehicle such as an automobile.

[0015] As shown in Figures 1 and 2, the wheel bearing device 1 has a configuration known as a 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 inner sealing member 9, and an outer sealing member 10.

[0016] Here, the inner side refers to the vehicle body side of the wheel bearing device 1 when it is attached to the vehicle body, and the outer side refers to the wheel side of the wheel bearing device 1 when it is attached to the vehicle body. The axial direction refers to the direction along the rotation axis X of the wheel bearing device 1, with one axial end side being the outer side and the other axial end side being the inner side. The direction perpendicular to the rotation axis of the wheel bearing device 1 is referred to as the radial direction. In the following description, the term "cross section" will be used to refer to a cross section that passes through the rotation axis of the wheel bearing device 1 and is parallel to the rotation axis of the wheel bearing device 1.

[0017] An inner-side outer raceway groove 2c and an outer-side outer raceway groove 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 into which fastening members (here, bolts) are inserted that fasten the vehicle body member and the outer ring 2. The inner end of the outer ring 2, on the inner side of the vehicle body mounting flange 2e, is configured as a cylindrical pilot portion 2g that is fitted into a vehicle knuckle.

[0018] The inner end of the outer peripheral surface of the hub ring 3 is formed with a small-diameter step 3a that is smaller in diameter than the outer end. A wheel mounting flange 3b that extends radially outward is integrally formed with the outer end of the hub ring 3 for mounting a wheel. A plurality of ribs 3d are formed on the wheel mounting flange 3b in the circumferential direction about the rotation axis X. An outer-side inner raceway groove 3c is provided on the outer peripheral surface of the hub ring 3 so as to face the outer outer raceway groove 2d on the outer ring 2. In other words, the inner raceway groove 3c is defined by the hub ring 3 on the outer side of the inner member. A plurality of bolt holes 3e are formed in the wheel mounting flange 3b, each penetrating the plurality of ribs 3d in the axial direction. A plurality of hub bolts 3f are press-fitted into the plurality of bolt holes 3e to fasten the hub ring 3 to a wheel or brake component. In other words, the plurality of hub bolts 3f are formed in the circumferential direction about the rotation axis X.

[0019] The inner ring 4 is mounted on the small diameter step 3a of the hub ring 3. The inner ring 4 is press-fitted into the small diameter step 3a via a specified interference. Furthermore, the hub ring 3 and the inner ring 4 are integrated by a crimped portion formed by plastically deforming and crimping the inner end of the small diameter step 3a of the hub ring 3, preventing the inner ring 4 from slipping out of the hub ring 3 in the axial direction. The inner ring 4 applies preload to the inner ball row 5 and outer ball row 6, which form the rolling rows. An inner-side inner raceway groove 4a is formed on the outer peripheral surface of the inner ring 4 so as to face the inner-side outer raceway groove 2c of the outer ring 2. In other words, the inner ring 4 defines the inner raceway groove 4a on the inner side of the inner member.

[0020] A bearing space, which is an annular space, is formed between the outer ring 2 and the hub ring 3. An outer seal member 10, which is a sealing device, is fitted into the outer end of the bearing space to prevent the intrusion of foreign matter such as muddy water.

[0021] An inner seal member 9, which is a sealing device, is fitted into the inner end of the bearing space between the outer ring 2 and the inner ring 4 to prevent the intrusion of foreign matter such as muddy water.

[0022] The inner ball row 5 and outer ball row 6, which are rolling rows, are rollably housed between the raceway grooves of the outer member and the inner member. The inner ball row 5 and outer ball row 6 are formed by a plurality of balls 7, which are rolling elements, held in a cage 8. The inner ball row 5 is rollably sandwiched between the outer raceway groove 2c on the inner side of the outer ring 2 and the inner raceway groove 4a of the inner ring 4. The outer ball row 6 is rollably sandwiched between the outer raceway groove 2d on the outer side of the outer ring 2 and the inner raceway groove 3c of the hub ring 3. In other words, the inner ball row 5 and outer ball row 6 are rollably housed between the raceway grooves of the outer member and the inner member. In the wheel bearing device 1, the outer ring 2, the hub ring 3 and the inner ring 4, the inner ball row 5, and the outer ball row 6 form a double-row angular contact ball bearing.

[0023] [Conditions for axial and radial dimensions of wheel bearing device] The wheel bearing device 1 is configured to satisfy at least one of Condition 1 and Condition 2. Condition 1 is a condition regarding the axial and radial sizes of the wheel bearing device 1. Condition 1 satisfies the relationship of 1.20≦a / b≦1.95, where a is the outer diameter a of the inner end portion (a cylindrical pilot portion that fits into the knuckle of a vehicle) of the outer ring 2 and b is the axial distance b from the outer side surface of the wheel mounting flange 3b of the hub ring 3 to the inner end portion of the inner ring 4. Condition 2 is a condition regarding the radial size of the wheel bearing device 1. Condition 2 satisfies the relationship of 0.60≦PCDo / PCDh≦0.73, where a is the pitch circle diameter PCDo of the outer ball row 6 and a pitch circle diameter PCDh of the hub bolt 3f of the hub ring 3. In this way, by satisfying either Condition 1 or Condition 2, the wheel bearing device 1 is configured to be relatively large in the radial direction. Furthermore, by satisfying both Condition 1 and Condition 2, the ball is configured to be relatively small in the axial direction and relatively large in the radial direction. Here, pitch circle diameter PCDo is the diameter when the radial distance from the rotation axis X to the center of the outer ball is taken as the radius, and pitch circle diameter PCDh is the diameter when the radial distance from the rotation axis X to the central axis of the hub bolt 3f is taken as the radius. Also, although the present embodiment uses hub bolts 3f, wheel bolts may be used instead of hub bolts.

[0024] [Specific configuration of outer seal member] The outer seal member 10 includes a core metal 11 and a seal member 12 .

[0025] The core metal 11 is a ring-shaped body made of, for example, a steel plate, and is fitted into the outer ring 2. The core metal 11 includes an inner fitting portion and an inner portion. The inner fitting portion is a cylindrical portion that is fitted into the radially inner surface of the outer end portion of the outer ring 2. The inner portion is a donut-shaped portion that extends radially inward from the outer end portion of the inner fitting portion.

[0026] The seal member 12 is made of, for example, synthetic rubber and is configured to be elastically deformable. The seal member 12 is joined to the core metal 11 by vulcanization bonding or the like, and is configured integrally with the core metal 11. The seal member 12 has multiple seal lips that contact the seal land portion 3g. The seal member 12 has a grease lip 12a and side lips 12b and 12c.

[0027] The grease lip 12a and side lips 12b and 12c of the seal member 12 constitute the seal lips of the seal member 12. The grease lip 12a extends from the inside of the core 11 toward the inner diameter side and the inner side, and contacts the seal land portion 3g. The side lip 12b extends from the inside of the core 11 toward the outer diameter side and the outer side, radially outward of the grease lip 12a, and contacts the seal land portion 3g. The side lip 12c extends from the inside of the core 11 toward the outer diameter side and the outer side, which is the wheel mounting flange 3b side, radially outward of the grease lip 12a and the side lip 12b, and contacts the seal land portion 3g.

[0028] [Structure of the wheel mounting flange of the hub wheel and the outer end of the outer ring] A seal land 3g, with which the outer seal member 10 comes into contact, is formed at the base of the wheel mounting flange 3b of the hub wheel 3. The seal land 3g is configured in an annular shape in the circumferential direction about the rotation axis X and is connected to the inner raceway groove 3c. In a cross section passing through the rotation axis X and parallel to the rotation axis X, the seal land 3g has an axial surface 3ga that is a straight surface parallel to the axial direction, an arc-shaped surface 3gb that is convex toward the inner diameter side, and a radial surface 3gc that is a straight surface parallel to the radial direction. The inner end of the axial surface 3ga is connected to the outer end of the inner raceway groove 3c. The inner end of the arc-shaped surface 3gb is connected to the outer end of the axial surface 3ga. The radially inner end of the radial surface 3gc is connected to the radially outer end of the arc-shaped surface 3gb.

[0029] The wheel mounting flange 3b of the hub wheel 3 has a flange side surface 3h on the inner side. The flange side surface 3h is composed of a flat surface parallel to the radial direction. The portion of the flange side surface 3h near the bolt hole 3e is configured as a bearing surface when the hub bolt 3f is fastened. The flange side surface 3h is located radially outward and on the outer side of the seal land portion 3g.

[0030] A step portion 3i is formed between the flange side surface 3h and the seal land portion 3g of the hub wheel 3. The step portion 3i is configured in an annular shape in the circumferential direction about the rotation axis X and connects the flange side surface 3h and the seal land portion 3g. The step portion 3i bends inward as it approaches the inner diameter side, and has an overall arc-shaped cross section that is convex toward the inner diameter side. The radially inner end of the step portion 3i is connected to the radially outer end of the radial surface 3gc of the seal land portion 3g. The boundary between the radially inner end of the step portion 3i and the radially outer end of the radial surface 3gc of the seal land portion 3g is configured as a first boundary P1. The radially outer end of the step portion 3i is connected to the radially inner end of the flange side surface 3h. The boundary between the radially outer end of the step portion 3i and the radially inner end of the flange side surface 3h is configured as a second boundary P2.

[0031] The outer end face 2h of the outer ring 2 is composed of a flat surface parallel to the radial direction. The outer ring 2 also has an inclined surface 2i. The inclined surface 2i is composed of a flat surface or a curved surface that has an inclination angle with respect to the axial direction, or a combined surface of a flat surface and a curved surface. Here, when the inclined surface 2i is a curved surface or a combined surface of a flat surface and a curved surface, the inclined surface 2i is defined as having an inclination angle even if the straight line connecting the connection point between the inclined surface 2i and the outer end face 2h and the connection point between the inclined surface 2i and the portion of the outer end of the outer ring 2 where the outer seal member 10 is fitted forms an angle with respect to the axial direction.

[0032] A predetermined gap is formed between the outer side end face 2h and the inclined surface 2i of the outer ring 2 and the stepped portion 3i of the hub ring 3, and it is configured as a labyrinth. The outer side end face 2h of the outer ring 2 and the stepped portion 3i of the hub ring 3 are configured to face each other in the axial direction. The outer side end face 2h and the inclined surface 2i of the outer ring 2 are located radially outside the first boundary P1. The outer side end face 2h and the inclined surface 2i of the outer ring 2 are located radially inside the second boundary P2.

[0033] The wheel bearing device 1 is configured to satisfy Condition 3. Condition 3 is such that for the inner diameter d0 of the portion where the outer seal member 10 is fitted at the outer end of the outer ring 2 and the diameter d1 of the first boundary P1 which is the radially outer end of the seal land portion 3g, the relationship d0≧d1 is satisfied. Here, the inner diameter d0 is the diameter when the radial distance from the rotation axis X to the portion where the outer seal member 10 is fitted is taken as the radius, and the diameter d1 is the diameter when the radial distance from the rotation axis X to the first boundary P1 is taken as the radius.

[0034] By configuring it in this way, the radius of curvature r of the stepped portion 3i of the hub ring 3 (the radius of curvature r of the arc-shaped portion of the stepped portion 3i) can be configured to be relatively large. Therefore, even if the wheel bearing device 1 is configured to satisfy at least one of Condition 1 and Condition 2, the generation of stress on the stepped portion 3i can be suppressed. Also, in this way, since Condition 3 (the relationship d0≧d1 for the inner diameter d0 of the outer end of the outer ring 2 and the diameter d1 of the first boundary P1) is satisfied and a predetermined gap is configured as a labyrinth between the outer side end face 2h and the inclined surface 2i of the outer ring 2 and the stepped portion 3i of the hub ring 3, it is possible to prevent foreign matter from entering from the outer side end of the bearing space between the outer ring 2 and the hub ring 3 toward the outer seal member 10 side. Compared with the case where the relationship d0<d1 is established, the amount and speed of inflow of muddy water to the contact portion between the seal lip 12c and the radial surface 3gc can be reduced, so the mud and water resistance is improved.

[0035] Furthermore, the wheel bearing device 1 is configured to satisfy at least one of Condition 4 and Condition 5. Condition 4 satisfies the relationship 0.04≦(r−h) / PCDh≦0.80, where r is the radius of curvature of the stepped portion 3i (the arc-shaped portion of the stepped portion 3i) of the hub ring 3, h is the axial length between a first boundary P1 that is the radially outer end of the seal land portion 3g and a second boundary P2 that is the radially inner end of the flange side surface 3h, and PCDh is the pitch circle diameter PCDh of the hub bolt 3f of the hub ring 3.

[0036] By configuring the wheel bearing device 1 to satisfy condition 4 in this way, the radius of curvature r of the step portion 3i of the hub wheel 3 can be configured to be relatively large, reducing the stress amplitude generated at the step portion 3i of the hub wheel 3 and improving the discharge efficiency of muddy water that has entered the labyrinth formed by the predetermined gap between the outer end face 2h and inclined surface 2i of the outer ring 2 and the step portion 3i of the hub wheel 3 (see FIG. 4(a)). Therefore, by satisfying conditions 3 and 4, the sealing performance of the outer seal member 10 can be ensured while stress concentration at the step portion 3i of the hub wheel 3 can be reduced.

[0037] Condition 5 satisfies the relationship 0.04≦(d1−d2) / (2×PCDh×tanθ)≦0.80, where d1 is the diameter of the first boundary P1, which is the radially outer end of the seal land portion 3g; d2 is the diameter of the second boundary P2, which is the boundary between the radially outer end of the stepped portion 3i and the radially inner end of the flange side surface 3h; PCDh is the pitch circle diameter of the hub bolt 3f of the hub ring 3; and θ is the angle θ of the tangent of the stepped portion 3i at the first boundary P1 relative to the radial direction. Here, diameter d2 is the diameter when the radial distance from the rotation axis X to the second boundary P2 is defined as the radius. Note that the wheel bearing device 1 shown in FIG. 3 satisfies Condition 5, and the radius of curvature r of the stepped portion 3i of the hub ring 3 is configured to be close to its upper limit. Also, as shown in FIG. 3, a tapered portion may be formed on the outer diameter surface of the outer ring 2. This allows the distance between the outer diameter surface of the outer ring 2 and the hub bolt 3f to be maintained appropriately.

[0038] By configuring the wheel bearing device 1 to satisfy condition 5 in this way, the radius of curvature r of the step portion 3i of the hub wheel 3 can be configured to be relatively large, reducing the stress amplitude generated at the step portion 3i of the hub wheel 3 and improving the discharge efficiency of muddy water that has entered the labyrinth formed by the predetermined gap between the outer end face 2h and inclined surface 2i of the outer ring 2 and the step portion 3i of the hub wheel 3 (see FIG. 4(b)). Therefore, by satisfying conditions 3 and 5, the sealing performance of the outer seal member 10 can be ensured while stress concentration at the step portion 3i of the hub wheel 3 can be reduced.

[0039] The wheel bearing device 1 may also be configured to satisfy conditions 4 and 5. By configuring the wheel bearing device 1 to satisfy conditions 4 and 5 in this way, the radius of curvature r of the stepped portion 3i of the hub ring 3 can be configured to be relatively large, the stress amplitude generated at the stepped portion 3i of the hub ring 3 can be reduced, and the efficiency of discharging muddy water that has entered the labyrinth formed by the predetermined gap between the outer end face 2h and inclined surface 2i of the outer ring 2 and the stepped portion 3i of the hub ring 3 can be improved. Therefore, by satisfying conditions 3, 4, and 5, the sealing performance of the outer seal member 10 can be ensured while stress concentration at the stepped portion 3i of the hub ring 3 can be reduced.

[0040] The radially inner end of the stepped portion 3i of the hub wheel 3 is connected to the radially outer end of the radial surface 3gc of the seal land portion 3g, and a tangent to the second boundary P2 of the stepped portion 3i is configured to be parallel to the flange side surface 3h.

[0041] By configuring in this manner, the radius of curvature r of the step portion 3i of the hub wheel 3 can be configured to be relatively large, reducing the stress amplitude generated at the step portion 3i of the hub wheel 3. Therefore, by satisfying condition 3, the sealing performance of the outer seal member 10 can be ensured while stress concentration at the step portion 3i of the hub wheel 3 can be reduced.

[0042] The wheel bearing device 1 is configured to satisfy condition 6. Condition 6 requires that the shortest distance C1 between the inclined surface 2i of the outer ring 2 and the stepped portion 3i of the hub ring 3 and the axial distance C2 between the outermost diameter portion of the outer end face 2h of the outer ring 2 and the stepped portion 3i of the hub ring 3 satisfy the relationship C1≦C2.

[0043] With this configuration, the inner side is narrower than the outlet side gap (gap at the radially outer end) in the predetermined labyrinth between the outer end face 2h and inclined surface 2i of the outer ring 2 and the stepped portion 3i of the hub ring 3. This makes it possible to more reliably prevent foreign matter from entering the bearing space between the outer ring 2 and hub ring 3 from the outer end to the outer seal member 10 side.

[0044] 5 and 6, the seal land 3g and step 3i of the hub ring 3 are configured in an annular shape extending circumferentially relative to the axial direction, and are also formed in areas where the ribs 3d are not formed. Even in areas where the ribs 3d are not formed on the hub ring 3, a predetermined gap is formed between the outer end face 2h and inclined surface 2i of the outer ring 2 and the step 3i of the hub ring 3, forming a labyrinth. Furthermore, even in areas where the ribs 3d are not formed on the hub ring 3, the configuration satisfies Condition 6 (where C1 is the shortest distance between the inclined surface 2i of the outer ring 2 and the step 3i of the hub ring 3, and C2 is the axial distance C2 between the outermost diameter part of the outer end face 2h of the outer ring 2 and the step 3i of the hub ring 3, and the relationship C1≦C2).

[0045] With this configuration, even in areas where the ribs 3d are not formed on the hub wheel 3, the labyrinth of a predetermined gap between the outer end face 2h and inclined surface 2i of the outer ring 2 and the stepped portion 3i of the hub wheel 3 is configured so that the inner side is narrower than the outlet side gap (gap at the radially outer end). Therefore, even in areas where the ribs 3d are not formed on the hub wheel 3, it is possible to more reliably prevent foreign matter from entering the outer end of the bearing space between the outer ring 2 and hub wheel 3 toward the outer seal member 10.

[0046] As shown in FIG. 7, the step portion 3i of the hub wheel 3 may be configured to include an arc-shaped surface 3ia having an arc-shaped cross section that convex toward the inner diameter side, and a straight surface 3ib disposed radially inward of the arc-shaped surface 3ia. The radially outer end of the arc-shaped surface 3ia is connected to the flange side surface 3h. In other words, the boundary between the radially outer end of the arc-shaped surface 3ia and the radially inner end of the flange side surface 3h is configured as a second boundary P2. The radially outer end of the straight surface 3ib is connected to the radially inner side of the arc-shaped surface 3ia, and the radially inner end of the straight surface 3ib is connected to the radially outer end of the radial surface 3gc of the seal land portion 3g. In other words, the boundary between the radially outer end of the straight surface 3ib and the radially outer end of the radial surface 3gc of the seal land portion 3g is configured as a first boundary P1. In the present embodiment, the configuration may be such that the relationship C1≦C2 is satisfied for the shortest distance C1 between the inclined surface 2i of the outer ring 2 and the stepped portion 3i (arcuate surface 3ia or straight surface 3ib) of the hub wheel 3, and the axial distance C2 between the outermost diameter portion of the outer end face 2h of the outer ring 2 and the stepped portion 3i (arcuate surface 3ia or straight surface 3ib) of the hub wheel 3. Furthermore, the radially inner end of the straight surface 3ib of the stepped portion 3i may be connected to the radially outer end of the radial surface 3gc of the seal land portion 3g, and the tangent to the arc-shaped surface 3ia of the stepped portion 3i at the second boundary P2 may be parallel to the flange side surface 3h.

[0047] By configuring in this manner, the radius of curvature r of the step portion 3i of the hub wheel 3 can be configured to be relatively large, reducing the stress amplitude generated at the step portion 3i of the hub wheel 3. Therefore, by satisfying condition 3, the sealing performance of the outer seal member 10 can be ensured while stress concentration at the step portion 3i of the hub wheel 3 can be reduced.

[0048] Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments, which are merely examples, and it goes without saying that the present invention can be embodied in various other forms without departing from the spirit of the present invention. The scope of the present invention is indicated by the claims, and further includes the equivalent meanings set forth in the claims, and all modifications within the scope of the claims. [Explanation of symbols]

[0049] 1 Wheel bearing device 2 outer ring 2c (inner side) outer raceway 2d (Outer side) outer raceway 2e Body mounting flange 2f bolt hole 2g Inner end (pilot part) 2h Outer end 2i Slope 3 Hub Wheel 3a Small diameter stepped section 3b Wheel mounting flange 3c Inner raceway surface 3d rib 3e Bolt hole 3f hub bolt 3g Seal land part 3h Flange side 3i Step part 4. Inner Circle 4a Inner raceway surface 5 Inner ball row 6 Outer ball row 7 Ball 8 Cage 9 Inner seal member 10 Outer seal member 11 Core 12 Sealing material 12a Grease Lip 12b Side Lip 12c side lip d0 Inner diameter of outer end of outer ring d1 Diameter of the first boundary P1 d2 Diameter of the second boundary P2 P1 first boundary P2 second boundary PCDo Pitch circle diameter of outer ball row PCDh Pitch circle diameter of hub bolt of hub ring 3 r Radius of curvature of step h is the axial length between the first boundary P1 and the second boundary P2

Claims

1. an outer ring which is an outer member having double-row outer raceway grooves on its inner periphery; an inner member including a hub ring having a small diameter stepped portion at an inner end of an outer periphery thereof, and an inner ring provided on the small diameter stepped portion of the hub ring, the inner member having double row inner raceway grooves facing the double row outer raceway grooves; an outer seal member fitted into an outer opening formed between the outer ring and the hub wheel; an inner-side ball row rollably accommodated between an outer raceway groove on an inner side of the outer ring and an inner raceway groove on the inner ring; a wheel bearing device including an outer side ball row rollably accommodated between an outer raceway groove on an outer side of the outer ring and an inner raceway groove of the hub ring, The hub wheel is a wheel mounting flange formed on an outer end of the hub wheel for mounting a wheel; a plurality of bolt holes axially passing through the wheel mounting flange; a plurality of bolts press-fitted into the plurality of bolt holes, respectively; a seal land portion formed at a base of the wheel mounting flange and contacting the outer seal member; an inner flange side surface of the wheel mounting flange; a step portion that connects the flange side surface and the seal land portion and has a cross section that is formed in an arc shape, a radially inner end of the step portion is connected to a radially outer end of the seal land portion, and a boundary portion between the radially inner end of the step portion and the radially outer end of the seal land portion is configured as a first boundary P1, a radially outer end of the step portion is connected to a radially inner end of the flange side surface, and a boundary portion between the radially outer end of the step portion and the radially inner end of the flange side surface is configured as a second boundary P2, Regarding the following conditions 1 to 5, At least one of Condition 1 and Condition 2 is satisfied, And condition 3 is satisfied, Furthermore, the wheel bearing device satisfies at least one of conditions 4 and 5. Condition 1: The relationship between the length a of the outer diameter of the inner end of the outer ring and the length b of the axial direction from the outer side surface of the wheel mounting flange of the hub ring to the inner side surface of the inner ring is 1.20≦a / b≦1.95 Condition 2: The pitch circle diameter PCDo of the outer ball row and the pitch circle diameter PCDH of the bolt of the hub wheel satisfy the relationship 0.60≦PCDo / PCDH≦0.

73. Condition 3: With respect to an inner diameter d0 of a portion of the outer end of the outer ring where the outer seal member is fitted, and a diameter d1 of the first boundary P1, the relationship d0 ≧ d1 is satisfied. Condition 4: where r is the radius of curvature of the step portion of the hub wheel, h is the axial length between the first boundary P1 and the second boundary P2, and PCDh is the pitch circle diameter of the bolt of the hub wheel, the relationship is 0.04≦(r−h) / PCDh≦0.80 Condition 5: where d1 is the diameter of the first boundary P1, d2 is the diameter of the second boundary P2, PCDh is the pitch circle diameter of the bolt of the hub wheel, and θ is the angle of the tangent of the stepped portion of the hub wheel at the first boundary P1 with respect to the radial direction, the relationship is 0.04≦(d1−d2) / (2×PCDh×tanθ)≦0.

80.

2. the outer ring includes an inclined surface connected to an outer end surface of the outer ring, the inclined surface is located radially inward of the outer-side end surface of the outer ring and has an inclination angle with respect to the axial direction, a predetermined gap is formed between the outer end surface and the inclined surface of the outer ring and the stepped portion of the hub wheel, 2. The wheel bearing device according to claim 1, which is configured to satisfy the following condition 6. Condition 6: The shortest distance C1 between the inclined surface of the outer ring and the stepped portion of the hub wheel and the axial distance C2 between the outermost diameter portion of the outer end face of the outer ring and the stepped portion of the hub wheel satisfy the relationship C1≦C2.

3. the hub wheel includes a plurality of ribs formed in a circumferential direction about a rotation axis, the ribs being formed with the bolts; The seal land portion and the step portion of the hub wheel are configured in an annular shape and are formed even in a portion where the rib is not formed, In a portion of the hub wheel where the rib is not formed, a predetermined gap is formed between the outer end surface and the inclined surface of the outer ring and the stepped portion of the hub wheel, 3. The wheel bearing device according to claim 2, which is configured to satisfy condition 6.

4. The wheel bearing device according to claim 1 , wherein a tangent to the second boundary P2 of the stepped portion of the hub wheel is configured to be parallel to a side surface of the flange.

5. the step portion of the hub wheel includes an arc-shaped surface having an arc-shaped cross section, and a straight surface disposed radially inward of the arc-shaped surface, A radially outer end of the arc-shaped surface is connected to the flange side surface, and a boundary portion between the radially outer end of the arc-shaped surface and the radially inner end of the flange side surface is configured as the second boundary P2. a radially outer end of the straight surface is connected to a radially inner side of the arc-shaped surface, 4. A wheel bearing device according to claim 1, wherein the radially inner end of the straight surface is connected to the radially outer end of the radial surface in the seal land portion, and the boundary portion between the radially outer end of the straight surface and the radially outer end of the radial surface in the seal land portion is configured as the first boundary P1.

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