Drive wheel bearing device

Abstract

A drive wheel bearing device 10 comprises a bearing 30 and a joint member 20 attached to the bearing 30. The joint member 20 has a cup part 22 and a shaft part 21 that extends from the cup part 22 in the axial direction and is connected to a hub ring 34 such that torque can be transmitted thereto. The cup part 22 has an abutment surface 23 that abuts an end surface of an inner ring 33 in the axial direction, and an extension surface 24 that extends from the abutment surface 23 toward the shaft part 21 and is positioned on the radially inner side of the inner ring 33. The inner ring 33 has an opposing surface 42 that is opposite of the extension surface 24. The extension surface 24 and the opposing surface 42 do not contact each other when a force M acting on the bearing 30 is less than a threshold M1 and contact each other when the force M acting on the bearing 30 is greater than or equal to the threshold M1.

Description

Bearing device for driving wheel

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

[0002] In a bearing device for a driving wheel in which a bearing called a hub unit and a joint member of a constant velocity universal joint are combined, without caulking the hub ring to the inner ring, by allowing a portion on the vehicle outer side of the joint member to enter radially inward of the inner ring, a structure with a shortened axial dimension is known (see Patent Document 1). The bearing device for a driving wheel having the above structure is used, for example, in a driving device of an automobile.

[0003] Japanese Patent Application Laid-Open No. 2017-133578

[0004] In the bearing device for a driving wheel having the above structure, the inner ring is provided with a tapered contact surface for allowing a portion on the vehicle outer side of the joint member to enter, radially inward. The contact surface is contacted with the cup portion of the joint member. In the bearing device for a driving wheel with a shortened axial dimension, the contact area between the contact surface and the cup portion is smaller than the contact area between the inner ring and the joint member in a conventional bearing device for a driving wheel whose axial dimension has not been shortened. Therefore, in the conventional bearing device for a driving wheel having a shortened structure, when receiving a turning load during vehicle turning, the force (surface pressure) for the inner ring to press the cup portion becomes large, and there is a risk that the joint member may be deformed.

[0005] The present disclosure aims to suppress deformation of a joint member in a bearing device for a driving wheel including a bearing and a joint member.

[0006] The drive wheel bearing device of the present disclosure comprises a bearing and a joint member assembled to the bearing, and rotatably supports a drive wheel of a vehicle, wherein the bearing comprises an outer member, an inner member including a hub ring and an inner ring, a plurality of hub rolling elements provided between the vehicle outer side raceway surface of the outer member and the raceway surface of the hub ring, and a plurality of inner ring rolling elements provided between the vehicle inner side raceway surface of the outer member and the raceway surface of the inner ring, and the joint member comprises a cup portion The bearing comprises a cup portion and a shaft portion extending axially from the cup portion and connected to the hub ring in a manner that torque can be transmitted, wherein the cup portion has a contact surface that abuts against the axial end face of the inner ring and an extended surface that extends from the contact surface toward the shaft portion and is located radially inward of the inner ring, and the inner ring has an opposing surface that faces the extended surface, wherein the extended surface and the opposing surface are not in contact when the magnitude of the force acting on the bearing is less than a threshold, and are in contact when the magnitude of the force is greater than or equal to the threshold.

[0007] According to this disclosure, in a bearing device for a drive wheel that includes a bearing and a joint member, deformation of the joint member can be suppressed.

[0008] Figure 1 is a cross-sectional view showing an example of a drive wheel bearing device according to the present disclosure. Figure 2 is a partially enlarged cross-sectional view of the drive wheel bearing device according to the present disclosure. Figure 3 is a partially schematic diagram showing the relationship between the opposing surface and the extended surface in the drive wheel bearing device (first embodiment) according to the present disclosure. Figure 4 is a schematic diagram showing the detailed shapes of the extended surface and the opposing surface in a conventional drive wheel bearing device. Figure 5 is a schematic diagram showing the detailed shapes of the extended surface and the opposing surface in the drive wheel bearing device according to the present disclosure. Figure 6 is a schematic diagram showing the detailed shapes (modified) of the extended surface and the opposing surface in the drive wheel bearing device according to the present disclosure. Figure 7 is an explanatory diagram of the relationship between the inclination of the bearing and the force acting on the cup portion. Figure 8 is a partially schematic diagram showing the relationship between the opposing surface and the extended surface in the drive wheel bearing device (second embodiment) according to the present disclosure.

[0009] <Details of Embodiments> Preferred embodiments will be described below with reference to the drawings.

[0010] [Overall Configuration of Drive Wheel Bearing Device] Figure 1 is a cross-sectional view showing an example of a drive wheel bearing device according to the present disclosure. The drive wheel bearing device 10 shown in Figure 1 (hereinafter also simply referred to as bearing device 10) is a wheel bearing device used for the drive wheels of an automobile, and is also called a hub unit. The bearing device 10 is attached to the suspension system of the automobile and rotatably supports the wheel and the disc rotor (not shown) of the brake system. The bearing device 10 comprises a joint member 20 and a bearing 30.

[0011] The joint member 20 is an axial member having a center line C1 and comprises a shaft portion 21 and a cup portion 22. The joint member 20 is part of a constant velocity universal joint that constitutes the suspension system of an automobile. The constant velocity universal joint is coupled to the drive shaft (not shown) of the automobile. The bearing device 10 receives rotational power from the drive shaft via the constant velocity universal joint, which includes the joint member 20.

[0012] The bearing 30 is a so-called hub unit bearing and comprises an outer member 31, an inner member 32, and a plurality of rolling elements (balls) 35. The bearing 30 has a center line C2. Although not described in detail, the bearing 30 further comprises a cage and a sealing device. The cage has an annular shape and holds the plurality of rolling elements 35. The sealing device has an annular shape and is positioned in the gap between the outer member 31 and the inner member 32 to prevent water, dust, etc. from entering the bearing 30.

[0013] The outer member 31 is a so-called outer ring and has a cylindrical shape. The inner member 32 has a portion located radially inward of the outer member 31. Multiple rolling elements 35 are arranged in two rows in the axial direction between the outer member 31 and the inner member 32. In the bearing device 10 under no load, the centerlines of the outer member 31 and the inner member 32 coincide. These centerlines coincide with the centerline C2 of the bearing 30.

[0014] The bearing device 10 has a center line C. The center line C coincides with the center line C1 of the joint member 20 and the center line C2 of the bearing 30. Figure 1 is a cross-sectional view in a plane including the center line C.

[0015] The following definitions apply to the bearing device 10 of this disclosure. The direction along the center line C of the bearing device 10 is the "axial direction." Note that the "axial direction" includes the direction parallel to the center line C. In the bearing device 10, one axial side (left side in Figure 1) is the vehicle inner side, and the other axial side opposite (right side in Figure 1) is the vehicle outer side. The direction perpendicular to the center line C is the "radial direction," and the direction along the circle centered on the center line C is the "circumferential direction." The direction in which the inner member 32 rotates around the center line C is the "circumferential direction."

[0016] Figure 2 is a partially enlarged cross-sectional view of the drive wheel bearing device of the present disclosure. Figure 2 shows cross-sections of the end of the cup portion 22 and the inner member 32 on the vehicle inner side. As shown in Figures 1 and 2, the cup portion 22 is located on the vehicle inner side of the inner member 32. The outer side of the cup portion 22 (shoulder portion 22c, which will be described later) (the contact surface 23, which will be described later) faces the inner side of the inner ring 33 (the end surface 41, which will be described later) in the axial direction.

[0017] The joint member 20 has a cylindrical cup portion 22 and a shaft portion 21 that extends from the cup portion 22 toward the vehicle outer side. As shown in Figure 2, the shaft portion 21 is provided to pass through the hub ring 34 (through hole 34c of the shaft body 34a, which will be described later) in the axial direction. The cup portion 22 has a bottomed cylindrical shape that opens toward the vehicle inner side. The cup portion 22 has a larger diameter than the shaft portion 21. The cup portion 22 has a cylindrical portion 22a and a bottom portion 22b that closes the cylindrical portion 22a toward the vehicle outer side. The outer circumference portion of the bottom portion 22b becomes the shoulder portion 22c of the cup portion 22.

[0018] As shown in Figure 2, the outer member 31 has a flange portion 31a on its outer circumference. The flange portion 31a is fixed to a part of the suspension system (not shown). The outer member 31 has a flange surface 31b formed on the vehicle inner side of the flange portion 31a. The outer member 31 has an outer raceway surface 36 on its inner circumference. The outer raceway surface 36 includes a first outer raceway surface 36a on the vehicle inner side and a second outer raceway surface 36b on the vehicle outer side.

[0019] As shown in Figures 1 and 2, the inner member 32 comprises an inner ring 33 and a hub ring 34. As shown in Figure 2, the hub ring 34 has a shaft body 34a and a flange portion 34b. The flange portion 34b is the part to which a wheel or the like is attached, and extends radially outward from the vehicle outer end of the shaft body 34a. The inner ring 33 is fixed to the vehicle inner portion of the shaft body 34a with a tightening allowance.

[0020] As shown in Figure 2, the inner ring 33 has a first inner raceway surface 37 on its outer circumference. The hub ring 34 has a second inner raceway surface 38 on its outer circumference. The shaft body 34a has a through hole 34c that penetrates axially. The center line of the through hole 34c coincides with the center line C of the bearing device 10. The through hole 34c has a portion that spline-fits with the shaft portion 21 of the joint member 20 and a portion that does not spline-fit with the shaft portion 21. The inner member 32 receives rotational power (rotational torque) from the joint member 20 via the portion that spline-fits with the shaft portion 21.

[0021] As shown in Figures 1 and 2, the rolling element 35 includes an inner wheel rolling element 35a included in the inner row on the vehicle side and a hub rolling element 35b included in the outer row on the vehicle side. As shown in Figure 2, the inner wheel rolling element 35a is provided between the first outer raceway surface 36a and the first inner raceway surface 37, and contacts the first outer raceway surface 36a and the first inner raceway surface 37 at a contact angle. The hub rolling element 35b is provided between the second outer raceway surface 36b and the second inner raceway surface 38, and contacts the second outer raceway surface 36b and the second inner raceway surface 38 at a contact angle.

[0022] As shown in Figure 1, the bearing device 10 includes a fastening member 27 for connecting the joint member 20 and the inner member 32. The fastening member 27 is a nut having a female thread and is screwed onto a male thread 28 formed on the other axial side of the shaft 21. When the fastening member 27 is tightened to a predetermined position on the male thread 28, it comes into close contact with the vehicle outer side surface of the shaft body 34a. When the fastening member 27 is further tightened from the predetermined position on the male thread 28, an axial force is applied to the hub ring 34 (shaft body 34a) in one axial direction, and an axial force is applied to the shaft 21 in the other axial direction. At this time, the inner ring 33 and the cup portion 22 (shoulder portion 22c) push against each other in the axial direction. As a result, the inner member 32 and the joint member 20 can rotate together as a single unit.

[0023] [Regarding the contact surface and extending surface] As shown in Figure 2, the cup portion 22 of the joint member 20 further has a contact surface 23 and an extending surface 24. The contact surface 23 is the end face on the other axial side of the shoulder portion 22c and is the part that contacts the end face on one axial side of the inner ring 33 (end face 41 which will be described later). The extending surface 24 is the side surface on the other axial side of the bottom portion 22b and extends from the contact surface 23 toward the shaft portion 21. The extending surface 24 is located radially inward of the inner ring 33 (opposing surface 42 which will be described later).

[0024] [Regarding the end face and opposing face] As shown in Figure 2, the inner ring 33 constituting the inner member 32 further has an end face 41 and an opposing face 42. The end face 41 is the end face on one axial side of the inner ring 33 and faces the contact surface 23. The end face 41 contacts the contact surface 23. The opposing face 42 is the portion that extends from the end face 41 toward the hub ring 34 and is located radially outward of the extending surface 24. The opposing face 42 faces the extending surface 24.

[0025] [Regarding the relationship between the opposing surface and the extending surface in the drive wheel bearing device of the first embodiment] Figure 3 is a partially schematic diagram showing the relationship between the opposing surface and the extending surface in the drive wheel bearing device (first embodiment) of the present disclosure. The bearing device 10 according to the first embodiment shown in Figure 3 has an inner ring 33 according to the first embodiment (hereinafter also referred to as the first inner ring 33X). Note that the first inner ring 33X and the joint member 20 shown in Figure 3 are in a state where they are not subjected to the turning load generated when the vehicle turns.

[0026] As shown in Figure 2, in the bearing device 10 under no load, the extending surface 24 and the opposing surface 42 face each other with a gap 45 between them. As shown in Figure 3, the gap 45 between the extending surface 24 and the opposing surface 42 of the first inner ring 33X is referred to as the first gap 45X.

[0027] In the bearing device 10 shown in Figure 3, the first gap 45X on the radially inner side is larger than the first gap 45X on the radially outer side. In other words, in the bearing device 10 according to the first embodiment, the width of the first gap 45X decreases toward one axial side and increases toward the other axial side.

[0028] In the bearing device 10 shown in Figure 3, the opposing surface 42 is a single plane, and the extending surface 24 is also a single plane. Therefore, the width of the first gap 45X increases at a constant rate (proportionally) from the radially outer side to the radially inner side (from one axial side to the other axial side). Although this embodiment illustrates a case where both the extending surface 24 and the opposing surface 42 are planes, the extending surface 24 and the opposing surface 42 may also include curved surfaces in part.

[0029] [Detailed Shape of Opposing and Extended Surfaces] Figure 4 is a schematic diagram showing the detailed shapes of the extended and opposing surfaces in a conventional drive wheel bearing device. Figure 4 shows in detail the contact state between the conventional joint member 120 (cup portion 122) and the conventional bearing 130 (inner ring 133) in a conventional drive wheel bearing device 110 (hereinafter also referred to as the conventional bearing device 110).

[0030] As shown in Figure 4, in the conventional joint member 120, the cup portion 122 includes a contact surface 123 and an extending surface 124. The cup portion 122 further includes a connecting portion 125 that connects the contact surface 123 and the extending surface 124. The connecting portion 125 is a concave curved surface (R surface). The connecting portion 125 has a first boundary portion 125X which is the boundary with the contact surface 123 and a second boundary portion 125Y which is the boundary with the extending surface 124. The curvature of the contact surface 123 and the connecting portion 125 changes with respect to the first boundary portion 125X. The curvature of the extending surface 124 and the connecting portion 125 changes with respect to the second boundary portion 125Y.

[0031] In a conventional bearing 130, the inner ring 133 has an end face 141 and an opposing face 142. The conventional inner ring 133 further includes a connecting portion 143 that connects the end face 141 and the opposing face 142. The connecting portion 143 is a convex curved surface (R surface). The connecting portion 143 has a first boundary portion 143X which is the boundary with the end face 141 and a second boundary portion 143Y which is the boundary with the opposing face 142. The curvature of the end face 141 and the connecting portion 143 changes with respect to the first boundary portion 143X. The curvature of the opposing face 142 and the connecting portion 143 changes with respect to the second boundary portion 143Y.

[0032] In a conventional bearing device 110, the extending surface 124 and the opposing surface 142 are substantially parallel and face each other with a gap 145 between them. In a conventional bearing device 110, the gap 145 on the radially outer side and the gap 145 on the radially inner side are substantially the same.

[0033] In a conventional bearing device 110 with such a configuration (see Figure 4), the first boundary portion 125X of the contact surface 123 and the connecting portion 125 is positioned radially inward compared to the first boundary portion 143X of the end surface 141 and the connecting portion 143. In this configuration, the bearing 130 (inner ring 133) is subjected to forces such as moment loads generated by the lateral force of the tires when the vehicle turns, or moment loads input when the vehicle collides with a curb or the like. When the force acting on the bearing 130 (inner ring 133) increases, the connecting portion 143 and the contact surface 123 interfere with each other, thereby hindering contact between the extending surface 124 and the opposing surface 142. Therefore, in the conventional bearing device 110 (see Figure 4), when the force acting on the bearing 130 (inner ring 133) increases, the opposing surface 142 does not come into contact with the joint member 120 (extended surface 124), and as a result, the force is concentrated at the contact point between the connecting portion 143 and the contact surface 123. Therefore, in the conventional bearing device 110 (see Figure 4), there is a risk that the cup portion 122 will deform.

[0034] Figure 5 is a schematic diagram showing the detailed shapes of the extending surface and opposing surface in the bearing device for a drive wheel of the present disclosure. Figure 5 shows in detail the contact state between the joint member 20 (cup portion 22) and the inner member 32 (inner ring 33) in the bearing device 10 of the present disclosure. As shown in Figure 5, in the joint member 20, the cup portion 22 is provided with a connecting portion (first connecting portion) 25 that connects the contact surface 23 and the extending surface 24. The connecting portion 25 is a concave curved surface (R surface). The connecting portion 25 has a first boundary portion 25X which is the boundary with the contact surface 23 and a second boundary portion 25Y which is the boundary with the extending surface 24. The curvature of the contact surface 23 and the connecting portion 25 changes with respect to the first boundary portion 25X. The curvature of the extending surface 24 and the connecting portion 25 changes with respect to the second boundary portion 25Y.

[0035] As shown in Figure 5, the inner ring 33 is provided with a connecting portion (second connecting portion) 43 that connects the end face 41 and the opposing face 42. The connecting portion 43 is a convex curved surface (R surface). The connecting portion 43 has a first boundary portion 43X which is the boundary with the end face 41, and a second boundary portion 43Y which is the boundary with the opposing face 42. The curvature of the end face 41 and the connecting portion 43 changes with respect to the first boundary portion 43X. The curvature of the opposing face 42 and the connecting portion 43 changes with respect to the second boundary portion 43Y.

[0036] In the bearing device 10 of this disclosure (see Figure 5), the contact surface 23 and the first boundary portion 25X of the connecting portion 25 are radially aligned with the end face 41 and the first boundary portion 43X of the connecting portion 43. In this configuration, when the force acting on the bearing 30 (inner ring 33) increases, the connecting portion 43 of the inner ring 33 and the contact surface 23 of the cup portion 22 do not interfere with each other, and contact between the extending surface 24 and the opposing surface 42 is not hindered. Therefore, with the bearing device 10 (see Figure 5), when the force acting on the bearing 30 increases, the concentration of force on the cup portion 22 due to contact between the connecting portion 43 and the contact surface 23 is avoided, the opposing surface 42 and the extending surface 24 can be reliably brought into contact, and the contact area between the opposing surface 42 and the extending surface 24 can be reliably increased. As a result, the bearing device 10 (see Figure 5) can suppress the force acting on the joint member 20 (extending surface 24) when a force is applied to the bearing 30.

[0037] [Regarding Modified Examples of the Extended Surface] Figure 6 is a schematic diagram showing the detailed shapes (modified examples) of the extended surface and opposing surface in the drive wheel bearing device of the present disclosure. Figure 6 shows in detail the contact state between the joint member 20 (cup portion 22) and the inner member 32 (inner ring 33) in the bearing device 10 according to a modified example of the present disclosure. In the bearing device 10 of the present disclosure, the joint member 20 (cup portion 22) and the inner member 32 (inner ring 33) may be configured as shown in Figure 6.

[0038] In the modified bearing device 10 shown in Figure 6, the connecting portion 25 that connects the contact surface 23 and the extending surface 24 has a recessed shape that avoids the connecting portion 43 of the inner ring 33. In the modified bearing device 10, the connecting portion 25 is a concave curved surface (relief radius surface).

[0039] In the bearing device 10 shown in Figure 6, the first boundary portion 25X of the contact surface 23 and the connecting portion 43 is positioned radially outward compared to the first boundary portion 43X of the end surface 41 and the connecting portion 43. In this configuration, when the force acting on the bearing 30 (inner ring 33) increases, the connecting portion 43 of the inner ring 33 and the contact surface 23 of the cup portion 22 do not interfere with each other, and contact between the extending surface 24 and the opposing surface 42 is not hindered. Therefore, when the force acting on the bearing 30 increases, the bearing device 10 (see Figure 6) can avoid the concentration of force on the cup portion 22 due to contact between the connecting portion 43 and the contact surface 23, ensure that the opposing surface 42 and the contact surface 23 are in reliable contact, and reliably increase the contact area between the opposing surface 42 and the extending surface 24. As a result, the bearing device 10 (see Figure 6) can suppress the force acting on the joint member 20 (extending surface 24) when a force is applied to the bearing 30.

[0040] [Relationship between bearing inclination and force acting on the cup portion] Figure 7 is an explanatory diagram of the relationship between bearing inclination and force acting on the bearing. In Figure 7, a description of a conventional bearing device 110 (see Figure 4) is shown as a "comparative example," and a description of the bearing device 10 of the present disclosure according to the first embodiment (see Figure 5) is shown as "Example 1." Figure 7 shows the relationship between the inclination angle θ of the flange portion of the bearing (flange portion 31a in the case of bearing device 10) and the force M acting on the bearing (bearing 130 in the case of bearing device 110, bearing 30 in the case of bearing device 10). The inclination angle θ is the angle formed between the flange surface on the vehicle inner side of the flange portion (flange surface 31b in the case of bearing device 10, see Figure 2) and a virtual plane perpendicular to the center line C.

[0041] As shown in Figure 7, in the conventional bearing device 110 (see Figure 4) relating to the "Comparative Example," the inclination angle θ of the bearing (flange portion) 130 and the magnitude of the force M acting on the bearing 130 are proportional. Therefore, in the conventional bearing device 110 (see Figure 4), the force M acting on the bearing 130 increases as the turning load during vehicle turning increases. This is thought to be because, in the conventional bearing device 110, as the force acting on the bearing 130 increases, the connecting portion 143 and the contact surface 123 interfere with each other, and contact between the extending surface 124 and the opposing surface 142 is hindered. As a result, the opposing surface 142 does not contact the joint member 120, and the force is concentrated at the position where the connecting portion 143 and the contact surface 123 are in contact. In this case, the cup portion 122 may deform as the force M acting on the bearing 130 increases.

[0042] On the other hand, in the bearing device 10 according to "Example 1" (see Figure 5), as the inclination angle θ of the bearing 30 (flange portion 31a) increases, the force M acting on the bearing 30 increases in proportion to the inclination angle θ until it reaches a predetermined threshold M1. This is because, when the force M acting on the bearing 30 is less than the threshold M1, the extending surface 24 and the opposing surface 42 are not yet in contact. In the bearing device 10 according to "Example 1" (see Figure 5), when the force M acting on the bearing 30 reaches the threshold M1, the extending surface 24 and the opposing surface 42 come into contact. Then, when the force M acting on the bearing 30 exceeds the threshold M1, the contact area between the extending surface 24 and the opposing surface 42 increases as the inclination angle θ of the flange portion 31a increases. This makes it possible to suppress the force acting on the cup portion 22 and to moderate the degree of increase in the force acting on the cup portion 22 as the inclination angle θ increases. Therefore, according to the bearing device 10 (see Figure 5) of the first embodiment of this disclosure, deformation of the cup portion 22 due to an increase in the force M acting on the bearing 30 can be suppressed.

[0043] As shown in FIG. 5, in the bearing device 10 according to "Embodiment 1", the contact surface 23 of the cup portion 22 and the first boundary portion 25X of the connecting portion 25, and the end surface 41 of the inner ring 33 and the first boundary portion 43X of the connecting portion 43 are arranged at positions that coincide in the radial direction. Alternatively, as shown in FIG. 6, in the bearing device 10 according to "Embodiment 1", the contact surface 23 of the cup portion 22 and the first boundary portion 25X of the connecting portion 25 are arranged on the outer side in the radial direction compared to the end surface 41 of the inner ring 33 and the first boundary portion 43X of the connecting portion 43. In these cases, there is no interference between the connecting portion 43 of the inner ring 33 and the contact surface 23 of the cup portion 22. Therefore, according to the configurations shown in FIGS. 5 and 6, the extending surface 24 and the opposing surface 42 can be stably brought into contact with each other, and thereby, as the force (see FIG. 7) acting on the bearing 30 (inner ring 33) increases, the contact area between the bearing 30 and the joint member 20 can be surely increased.

[0044] As described above, the bearing device 10 of the first embodiment has a bearing 30 and a joint member 20 assembled to the bearing 30, and is a bearing device for a driving wheel that rotatably supports the driving wheel of a vehicle. The bearing 30 includes an outer member 31, an inner member 32 including a hub ring 34 and an inner ring 33, a plurality of hub rolling elements 35b provided between the second outer raceway surface 36b on the vehicle outer side of the outer member 31 and the second inner raceway surface 38 of the hub ring 34, and a plurality of inner ring rolling elements 35a provided between the first outer raceway surface 36a on the vehicle inner side of the outer member 31 and the first inner raceway surface 37 of the inner ring 33. The joint member 20 has a cup portion 22 and a shaft portion 21 that extends axially from the cup portion 22 and is connected to the hub ring 34 so as to be able to transmit torque. The cup portion 22 has a contact surface 23 that contacts the end surface of the inner ring 33 in the axial direction, and an extending surface 24 that extends from the contact surface 23 toward the shaft portion 21 and is located radially inside the inner ring 33. The inner ring 33 has an opposing surface 42 that opposes the extending surface 24, and the extending surface 24 and the opposing surface 42 are non-contact when the magnitude of the force M acting on the bearing 30 is less than the threshold value M1, and are in contact when the magnitude of the force M is greater than or equal to the threshold value M1.

[0045] In the bearing device 10 configured as described above, when the bearing 30 receives a force of a magnitude equal to or greater than the threshold value M1, the extending surface 24 of the joint member 20 and the opposing surface 42 of the inner ring 33 come into contact with each other. At this time, the contact area between the bearing 30 and the joint member 20 increases. As a result, when a force M acts on the bearing 30, the force acting on the joint member 20 (extending surface 24) can be suppressed. Therefore, according to the bearing device 10 according to the first embodiment including the bearing 30 and the joint member 20, deformation of the joint member 20 can be suppressed.

[0046] Further, in the bearing device 10 of the present embodiment, when the magnitude of the force acting on the bearing 30 is less than the threshold value M1, the extending surface 24 and the opposing surface 42 face each other with a first gap 45X, and the first gap 45X on the inner side in the radial direction is larger than the first gap 45X on the outer side in the radial direction. According to such a configuration, as the force acting on the bearing 30 increases, the contact area between the bearing 30 and the joint member 20 can be increased. As a result, when a force M acts on the bearing 30, the surface pressure acting on the extending surface 24 can be gradually increased, and the influence on the user's feeling of use can be suppressed.

[0047] Regarding the relationship between the opposing surface and the extending surface in the bearing device for a driving wheel according to the second embodiment] FIG. 8 is a partial schematic view showing the relationship between the opposing surface and the extending surface in the bearing device for a driving wheel (second embodiment) of the present disclosure. The bearing device 10 according to the second embodiment shown in FIG. 8 is different from the bearing device (see FIG. 3) according to the first embodiment in that it has an inner ring 33 according to the second embodiment (hereinafter also referred to as the second inner ring 33Y). Note that the second inner ring 33Y and the joint member 20 shown in FIG. 8 are in a state of not receiving the turning load generated during vehicle turning.

[0048] As shown in FIG. 8, in the bearing device 10 (see FIGS. 1 and 2) having the inner ring 33 (second inner ring 33Y) according to the second embodiment, the opposing surface 42 has a gap 45 with the extending surface 24. In the following description, the gap 45 in this case is also referred to as the second gap 45Y.

[0049] In the bearing device 10 shown in Figure 8, the opposing surface 42 includes a first opposing surface 42a, a second opposing surface 42b, and a stepped portion 42c. The first opposing surface 42a and the second opposing surface 42b are connected by the stepped portion 42c. In the second inner ring 33Y, the opposing surface 42 is composed of multiple planes including the first opposing surface 42a and the second opposing surface 42b. In the bearing device 10 shown in Figure 8, the extending surface 24 is a single plane.

[0050] In the bearing device 10 shown in Figure 8, the width of the second gap 45Y between the second opposing surface 42b and the extending surface 24 is larger than the width of the second gap 45Y between the first opposing surface 42a and the extending surface 24. Therefore, in the bearing device 10 shown in Figure 8, the second gap 45Y on the radially inner side is larger than the second gap 45Y on the radially outer side. In other words, in the bearing device 10 shown in Figure 8, the second gap 45Y on the other axial side is larger than the second gap 45Y on the one axial side.

[0051] In Figure 7, the bearing device 10 according to the second embodiment (see Figure 8) is illustrated as "Embodiment 2". As shown in Figure 7, in the bearing device 10 according to "Embodiment 2" (see Figure 8), as the inclination angle θ of the bearing 30 (flange portion 31a) increases, the force M acting on the bearing 30 increases in proportion to the inclination angle θ until it reaches a predetermined threshold M2. This is because when the force M acting on the bearing 30 is less than the threshold M2, the first opposing surface 42a and the extending surface 24 are not yet in contact. In the bearing device 10 according to "Embodiment 2" (see Figure 8), when the force M acting on the bearing 30 reaches the threshold M2, the first opposing surface 42a and the extending surface 24 come into contact. Then, when the force M acting on the bearing 30 exceeds the threshold M2, the contact area between the first opposing surface 42a and the extending surface 24 increases as the inclination angle θ of the flange portion 31a increases. This makes it possible to suppress the force acting on the cup portion 22 and to moderate the degree of increase in the force acting on the cup portion 22 as the inclination angle θ increases. For this reason, according to the bearing device 10 (see Figure 8) of the second embodiment of this disclosure, it is possible to suppress the deformation of the cup portion 22 as the force M acting on the bearing 30 increases.

[0052] As described above, the bearing device 10 of the second embodiment is a drive wheel bearing device 10 that rotatably supports the drive wheel of a vehicle, comprising a bearing 30 and a joint member 20 assembled to the bearing 30. The bearing 30 comprises an outer member 31, an inner member 32 including a hub wheel 34 and an inner wheel 33, a plurality of hub rolling elements 35b provided between the second outer raceway surface 36b on the wheel side of the outer member 31 and the second inner raceway surface 38 of the hub wheel 34, and a plurality of inner wheel rolling elements 35a provided between the first outer raceway surface 36a on the vehicle body side of the outer member 31 and the first inner raceway surface 37 of the inner wheel 33. The joint member 20 comprises a cup portion 22 and a shaft portion 21 extending axially from the cup portion 22 and connected to the hub wheel 34 so as to transmit torque. The cup portion 22 has a contact surface 23 that abuts against the axial end face of the inner ring 33, and an extended surface 24 that extends from the contact surface 23 toward the shaft portion 21 and is located radially inward of the inner ring 33. The inner ring 33 has a first opposing surface 42a that faces the extended surface 24, and the extended surface 24 and the first opposing surface 42a are not in contact when the magnitude of the force M acting on the bearing 30 is less than the threshold M2, and are in contact when the magnitude of the force M is equal to or greater than the threshold M2.

[0053] In a bearing device 10 with this configuration, when the bearing 30 receives a force M of a magnitude greater than or equal to a threshold M2, the extending surface 24 of the joint member 20 and the first opposing surface 42a of the inner ring 33 come into contact. At this time, the contact area between the bearing 30 and the joint member 20 increases. This makes it possible to suppress the force acting on the joint member 20 (extending surface 24) when a force is applied to the bearing 30. As a result, according to this second embodiment of the bearing device 10, deformation of the joint member 20 can be suppressed in a bearing device 10 that includes a bearing 30 and a joint member 20.

[0054] Furthermore, in the bearing device 10 of this embodiment, when the magnitude of the force M acting on the bearing 30 is less than the threshold M2, the extending surface 24 and the first opposing surface 42a and the second opposing surface 42b face each other with a second gap 45Y, and the second gap 45Y on the radially inner side is larger than the second gap 45Y on the radially outer side. With this configuration, the contact area between the bearing 30 and the joint member 20 can be increased as the force M acting on the bearing 30 increases. As a result, the surface pressure acting on the extending surface 24 when a force M acts on the bearing 30 can be gradually increased, and the impact on the user's feel can be minimized.

[0055] As shown in Figure 7, the threshold value M1 of the bearing device 10 according to "Example 1" (see Figure 5) is smaller than the threshold value M2 of the bearing device 10 according to "Example 2" (see Figure 8). Therefore, the bearing device 10 according to "Example 1" (see Figure 5) can suppress the force acting on the cup portion 22 more effectively than the bearing device 10 according to "Example 2" (see Figure 8).

[0056] Furthermore, the bearing device 10 according to "Example 1" (see Figure 5) can suppress the abrupt change in force (rapid change in surface pressure acting on the extending surface 24) between the non-contact and contact states of the opposing surface 42 and the extending surface 24, compared to the bearing device 10 according to "Example 2" (see Figure 8), thereby minimizing the impact on the user's feel.

[0057] The embodiments disclosed herein are illustrative in all respects and are not restrictive. The scope of the present invention is not limited to the embodiments described above and includes all modifications within the scope of equivalence to the configurations described in the claims.

[0058] 10 Bearing device for drive wheel 20 Joint member 21 Shaft portion 22 Cup portion 23 Contact surface 24 Extending surface 25 Connection portion (first connection portion) 25X First boundary portion (boundary portion) 30 Bearing 31 Outer member 32 Inner member 33 Inner ring 36a First outer raceway surface (raceway surface) 36b Second outer raceway surface (raceway surface) 37 First inner raceway surface (raceway surface) 38 Second inner raceway surface (raceway surface) 34 Hub ring 35 Rolling element 35a Inner ring rolling element 35b Hub rolling element 41 End face 42 Opposing surface 42a First opposing surface (opposing surface) 43 Connection portion (second connection portion) 43X First boundary portion (boundary portion) 45 Gap 45X First gap 45Y Second gap M Force acting on the bearing: M1 (force magnitude) threshold, M2 (force magnitude) threshold.

Claims

1. A drive wheel bearing device for rotatably supporting a drive wheel of a vehicle, comprising a bearing and a joint member assembled to the bearing, wherein the bearing comprises an outer member, an inner member including a hub ring and an inner ring, a plurality of hub rolling elements provided between the vehicle outer side raceway surface of the outer member and the hub ring raceway surface, and a plurality of inner ring rolling elements provided between the vehicle inner side raceway surface of the outer member and the inner ring raceway surface, the joint member comprises a cup portion and a shaft portion extending axially from the cup portion and connected to the hub ring in a manner that can transmit torque, the cup portion comprises a contact surface that abuts the axial end face of the inner ring, and an extended surface extending from the contact surface toward the shaft portion and located radially inward of the inner ring, the inner ring comprises an opposing surface facing the extended surface, and the extended surface and the opposing surface are A bearing device for a drive wheel, which is non-contact when the magnitude of the force acting on the bearing is less than a threshold, and contacts the bearing when the magnitude of the force is equal to or greater than the threshold.

2. When the magnitude of the force acting on the bearing is less than a threshold, the extending surface and the opposing surface are facing each other with a gap between them, and the gap on the radially inner side is larger than the gap on the radially outer side, as described in claim 1.

3. The drive wheel bearing device according to claim 1 or claim 2, wherein the cup portion has a first connecting portion that connects the contact surface and the extended surface, the inner ring has a second connecting portion that connects the end surface and the opposing surface, and the boundary portion of the cup portion between the contact surface and the first connecting portion is radially aligned with the boundary portion of the inner ring between the end surface and the second connecting portion, or is positioned radially outward from the boundary portion of the inner ring between the end surface and the second connecting portion.

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