Wheel bearing device

Abstract

To provide a wheel bearing device high in flexural rigidity and capable of enhancing a load capacity during torque transmission.SOLUTION: An outside joint member 31 and a hub ring 16 are joined in a torque transmissive manner with their face splines 51, 52 engaging with each other and axial tightening force operating between both face splines 51, 52. In the process of making both face splines 51, 52 close to each other in the axial direction to engage with each other, the tooth surface shapes of both face splines 51, 52 are determined so that tooth surfaces 51a, 51b of both face splines 51, 52 first contact each other at an intermediate part Eb, out of an outer diameter part Ea, an inner diameter part Ec, and the intermediate part Eb held between the outer diameter part and the inner diameter part in a region X where both face splines engage with each other.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a wheel bearing device for supporting a wheel of a vehicle such as an automobile so as to be rotatable relative to a vehicle body. [Background technology]

[0002] A known wheel bearing device in which a double-row rolling bearing (wheel bearing) and a constant velocity universal joint are unitized is one in which torque is transmitted between a hub wheel and an outer joint member of the constant velocity universal joint via face splines provided on the end face of the hub wheel and the end face of the outer joint member, respectively (see, for example, FIG. 7 of Patent Document 1). In this wheel bearing device, a bolt member is inserted into the hub wheel and, with the seating surface of the bolt member engaged with the end face of the hub wheel, the bolt member is screwed into a threaded hole provided in the bottom of the bowl-shaped portion of the outer joint member, thereby connecting the outer joint member and the hub wheel.

[0003] In wheel bearing devices that use face splines in this manner, there are known types in which, when the face splines are meshed together, the teeth of both face splines are first brought into contact on the radially outer side, and as the tightening increases, the teeth are also brought into contact on the radially inner side (Patent Document 2), and there is also a type in which the teeth are first brought into contact on the radially inner side, and as the tightening increases, the teeth are also brought into contact on the radially outer side (Patent Document 3). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2009-115292 A [Patent Document 2] Patent No. 5039048 [Patent Document 3] US Patent Application Publication No. 2015 / 0021973 Summary of the Invention [Problem to be solved by the invention]

[0005] Patent Document 2 describes that the first and second teeth come into contact with each other over the entire length of the tooth flanks of both teeth when the tightening force reaches approximately 75% of the normal tightening force (paragraph 0028). However, machining errors are unavoidable when machining the face spline, and therefore the shape of the tooth flanks cannot be manufactured as ideally as possible. Therefore, although it may be theoretically possible, it is actually difficult to bring the tooth flanks into contact with each other over the entire radial length of the tooth flanks of both teeth after a certain tightening force is applied, and the tooth flanks of both face splines can only come into contact with each other in a part of the meshing region.

[0006] Furthermore, when the face splines are meshed with each other, the portion that comes into contact with the mating side in the first half of the meshing operation often becomes the contact area between the tooth flanks during torque transmission. Therefore, after the application of the tightening force, in the configuration of Patent Document 2, the contact area between the tooth flanks is mainly on the outer diameter side of the radial meshing area between the tooth flanks, while in the configuration of Patent Document 3, the contact area between the tooth flanks is mainly on the inner diameter side.

[0007] When torque is transmitted with the constant velocity universal joint of the wheel bearing device at an operating angle, a bending moment repeatedly acts on the connection between the outer joint member of the constant velocity universal joint and the hub wheel. Therefore, when the contact area between the tooth surfaces is present on the outer diameter side as in Patent Document 2, in a part of the circumferential direction of the meshing area (the area where the mountain breaks when the bending moment is applied), the tooth surfaces are not in contact with each other on the outer diameter side of the meshing area between the face splines through the deformation of the bolt member. This significantly reduces the area of ​​the contact area in the meshing area, so that the meshing between the face splines may be disengaged. In particular, in the meshing area between the face splines, as shown in FIG. 10, during torque transmission, a component force Fa in the direction along the tooth surface of the torque transmission force F acting between the tooth surfaces 151a, 152a acts in a direction to disengage the meshing between the teeth, so that the meshing between the face splines becomes more likely to be disengaged. Therefore, the configuration of Patent Document 2 has a problem of reduced bending rigidity of the wheel bearing device.

[0008] On the other hand, in a configuration such as that in Patent Document 3, in which the contact area between the tooth surfaces during torque transmission is on the inner diameter side, there is no contact area on the outer diameter side, so the effect that the bending moment has on the bending rigidity of the wheel bearing device is reduced. However, since the rotation radius of the contact area is small, there is a problem that the load capacity during torque transmission is reduced, making it difficult to transmit high torque.

[0009] In view of the above, an object of the present invention is to provide a wheel bearing device that has high bending rigidity and is capable of increasing the load capacity during torque transmission. [Means for solving the problem]

[0010] The present invention provides a wheel bearing including an inner member having a double-row inner raceway surface and a flange portion for mounting to a wheel, an outer member having a double-row outer raceway surface, and a plurality of rolling elements arranged between the opposing inner raceway surface and outer raceway surface, and a constant velocity universal joint having an outer joint member, the outer joint member and the inner member being coupled to each other so as to be capable of transmitting torque by engaging face splines provided on each of the outer joint member and applying an axial tightening force between both face splines. The face splines each have a tooth surface between a tooth tip and a tooth bottom. In the wheel bearing device, in the process of bringing both face splines closer to each other in the axial direction and meshing with each other, a radial region including an outer diameter end of the tooth tip surface, and a region located on the inner diameter side of the radial region and separated from the radial region, the meshing region being sandwiched between a radial region including an inner diameter end of the tooth tip surface, the radial region including the outer diameter end, and the radial region including the inner diameter end Among the above, A region sandwiched between a radial region including an outer diameter end and a radial region including the inner diameter end The tooth flank shapes of both face splines are determined so that the tooth flanks of both face splines come into contact with each other first. and after the tooth flanks come into contact with each other in a region sandwiched between the radial region including the outer diameter end and the radial region including the inner diameter end, the tooth flanks come into contact with each other in the radial region including the outer diameter end and the radial region including the inner diameter end, and when the tooth flanks come into contact with each other, the tooth flanks come into contact with each other on both sides of the teeth of one of the face splines. It is characterized by:

[0011] In the process of bringing the two face splines closer to each other in the axial direction and meshing with each other, in the region where the tooth flanks contact each other at the initial stage, both tooth flanks elastically deform as the meshing progresses, and the contact state is maintained. Therefore, even if there is some machining error in the tooth flanks, the region where the tooth flanks contact each other at the initial stage remains a contact region where the tooth flanks contact each other during torque transmission. With the above configuration, at least The area between the radial area including the outer diameter end and the radial area including the inner diameter endSince a contact area is formed between the tooth surfaces, a bending moment acts due to the torque transmission of the constant velocity joint with an operating angle, which causes the meshing of both face splines on the outer diameter side to come off. The area between the radial area including the outer diameter end and the radial area including the inner diameter end In this case, the contact area between the tooth surfaces is maintained. Therefore, the meshing of both face splines does not come out. The area between the radial area including the outer diameter end and the radial area including the inner diameter end Since the contact area between the tooth surfaces is present, the radius of rotation of the contact area is generally large, making it possible to ensure a sufficient load capacity during torque transmission.

[0012] In such a configuration, The area between the radial area including the outer diameter end and the radial area including the inner diameter end Next, Radial area including outer diameter end The tooth surfaces of both face splines come into contact with each other. Then, the tooth surfaces of both face splines come into contact with each other in the radial area including the inner diameter end. It is preferable that the tooth flank shapes of both face splines are determined so that the contact area between the tooth flanks during torque transmission is expanded in the outer diameter direction, thereby further increasing the load capacity during torque transmission.

[0013] Of the meshing regions of the two face splines, the inner diameter end of the tooth tip surface of one of the face splines is set to 0%, the outer diameter end is set to 100%, and the region from 50% to 90% is set to A region sandwiched between a radial region including the outer diameter end and a radial region including the inner diameter end. It is preferable to set the above.

[0014] In this way, more than 50% of the tooth tip area , a region sandwiched between a radial region including the outer diameter end and a radial region including the inner diameter end By so doing, the contact area between the tooth flanks during torque transmission is formed on the outer diameter side, making it possible to further increase the load capacity during torque transmission. Effect of the Invention

[0015] As described above, according to the present invention, it is possible to provide a wheel bearing device which has high bending rigidity and is capable of increasing the load capacity during torque transmission. [Brief description of the drawings]

[0016] [Figure 1] 1 is a cross-sectional view of a wheel bearing device taken along an axial direction. [Diagram 2]FIG. 4 is a front view of the outer joint member as viewed from the outboard side. [Diagram 3] 2 is a cross-sectional view showing a process in which face splines are brought closer to each other in the axial direction and meshed with each other in the wheel bearing device shown in FIG. 1. [Figure 4] FIG. 2 is a cross-sectional view of a meshing region of a face spline taken along a circumferential direction. [Diagram 5] FIG. 4 is a front view of the meshing region of the face spline as viewed from the axial direction. [Figure 6] 2(a) and 2(b) are both enlarged cross-sectional views showing a first face spline of the wheel bearing device shown in FIG. 1. [Figure 7] 2(a) and 2(b) are both enlarged cross-sectional views showing a first face spline of the wheel bearing device shown in FIG. 1. [Figure 8] 2(a) and 2(b) are both enlarged cross-sectional views showing a first face spline of the wheel bearing device shown in FIG. 1. [Figure 9] 2(a) and 2(b) are both enlarged cross-sectional views showing a first face spline of the wheel bearing device shown in FIG. 1. [Figure 10] FIG. 2 is a cross-sectional view of a meshing region of a face spline taken along a circumferential direction. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, a wheel bearing device according to an embodiment of the present invention will be described with reference to Figures 1 to 9(a) and (b). In the following description, the direction that is on the outside in the vehicle width direction when mounted on the vehicle body is referred to as the outboard side, and the direction that is on the inside in the vehicle width direction is referred to as the inboard side.

[0018] As shown in FIG. 1, a wheel bearing device 1 according to this embodiment has a structure in which a wheel bearing 2 and a constant velocity universal joint 3 are integrated into a unit.

[0019] The wheel bearing 2 has as its main components an inner member 7 having double-row inner raceway surfaces 5, 6, an outer member 12 arranged on the outer diameter side of the inner member 7 and having double-row outer raceway surfaces 10, 11, a plurality of rolling elements 13 arranged between the radially opposing inner raceway surfaces 5, 6 and outer raceway surfaces 10, 11, and a retainer (not shown) that holds the rolling elements 13 at equal intervals in the circumferential direction.

[0020] The inner member 7 has a hub wheel 16 and an inner ring 17 fixed to the outer periphery of the hub wheel 16. One inner raceway surface 5 of double row inner raceway surfaces 5, 6 is formed on the outer periphery surface of the hub wheel 16, and the other inner raceway surface 6 is formed on the outer periphery surface of the inner ring 17.

[0021] The hub wheel 16 includes a flange portion 18 that is attached to a wheel of a vehicle, and a cylindrical tubular portion 19. The flange portion 18 of the hub wheel 16 is provided with a bolt mounting hole 20. Hub bolts for fixing the wheel and the brake rotor to the flange portion 18 are fixed to the bolt mounting hole 20. A small diameter portion 21 is formed at the inboard end of the tubular portion 19, and the inner ring 17 is press-fitted and fixed to the outer circumferential surface of the small diameter portion 21. A crimped portion 22 is formed at the inboard end of the tubular portion 19 of the hub wheel 16 by plastically deforming the inner diameter side by crimping after the inner ring 17 is press-fitted into the small diameter portion 21. The crimped portion 22 is in close contact with the inboard end surface of the inner ring 17. The crimped portion 22 determines the position of the inner ring 17 and applies a predetermined preload to the inside of the wheel bearing 2. An inner wall portion 23 that protrudes to the inner diameter side is provided on the inner circumferential surface on the outboard side of the tubular portion 19 of the hub wheel 16. The inner wall portion 23 has an axial through hole 24 on its axis. A bolt member 26 is inserted into the through hole 24 from the outboard side.

[0022] The constant velocity universal joint 3 is a fixed type constant velocity universal joint that allows only angular displacement and does not allow axial displacement. The main components of this constant velocity universal joint 3 are an outer joint member 31 having a cup-shaped mouth portion 30, an inner joint member 32 housed on the inner diameter side of the mouth portion 30 of the outer joint member 31, and a ball 33 as a torque transmission member disposed between the inner joint member 32 and the outer joint member 31. A female spline 34 is formed on the inner peripheral surface of the central hole of the inner joint member 32, and a male spline formed on the end of an intermediate shaft (not shown) is inserted into this female spline 34. In this way, the inner joint member 32 and the intermediate shaft are coupled to each other so as to be able to transmit torque.

[0023] Axial track grooves 35 are formed at multiple locations in the circumferential direction on the spherical inner peripheral surface of the mouth portion 30, and axial track grooves 36 are formed at multiple locations in the circumferential direction on the spherical outer peripheral surface of the inner joint member 32. The track grooves 35 of the outer joint member 31 and the track grooves 36 of the inner joint member 32, which face each other in the radial direction, form pairs, and balls 33 are rollably incorporated in each of the ball tracks formed by each pair of track grooves 35, 36. The balls 33 are held at equally spaced positions in the circumferential direction by a cage 37. The spherical outer peripheral surface of the cage 37 contacts the spherical inner peripheral surface of the outer joint member 31, and the spherical inner peripheral surface of the cage 37 contacts the spherical outer peripheral surface of the inner joint member 32.

[0024] In FIG. 1 , the groove bottom of the track groove 35 of the outer joint member 31 is straight at the opening side end of the mouth part 30, and the groove bottom of the track groove 36 of the inner joint member 32 is straight at the rear side end of the mouth part 30 (undercut-free type), but the groove bottoms of both the track groove 35 of the outer joint member 31 and the track groove 36 of the inner joint member 32 can also be formed into curved shapes as a whole.

[0025] When an operating angle is applied between the outer joint member 31 and the inner joint member 32, the balls 33 held in the cage 37 are always maintained within the plane bisecting the operating angle regardless of the operating angle. This ensures constant velocity between the outer joint member 31 and the inner joint member 32. Between the outer joint member 31 and the inner joint member 32, rotational torque is transmitted via the balls 33 while constant velocity is ensured.

[0026] The mouth portion 30 has a bottom portion 39 on which a female thread portion 38 is formed, the female thread portion 38 being centered on the axis. By screwing the male thread portion 27 formed on the tip of the bolt member 26 into the female thread portion 38, the bearing surface 26a of the bolt member 26 engages with the outboard end surface 23a of the inner wall portion 23 in the axial direction. By further screwing the bolt member 26, an axial tightening force is applied between the outer joint member 31 and the hub wheel 16 in a direction that brings them closer together.

[0027] A torque transmission portion 50 is provided between the inner member 7 of the wheel bearing 2 and the bottom portion 39 of the mouth portion 30 of the outer joint member 31. This torque transmission portion 50 is configured by engaging a first face spline 51 formed on the joint 3 side with a second face spline 52 formed on the bearing 2 side.

[0028] In this embodiment, the first face spline 51 is formed on the outboard end surface of the bottom portion 39 of the mouth portion 30, and the second face spline 52 is formed on the inboard end surface of the crimped portion 22 of the hub wheel 16. Fig. 2 shows the first face spline 51 as viewed from the axial direction. As shown in Fig. 2, the first face spline 51 has a configuration in which a plurality of radially extending convex stripes 53 and a plurality of radially extending concave stripes 54 are alternately arranged in the circumferential direction. Although not shown, the second face spline 52, like the first face spline 51, also has a configuration in which a plurality of radially extending convex stripes and a plurality of radially extending concave stripes are alternately arranged in the circumferential direction. The first face spline 51 and the second face spline 52 are meshed with each other, and the bolt member 26 is screwed into the female thread portion 38 to apply an axial tightening force between the two face splines 51, 52, whereby the outer joint member 31 and the hub wheel 16 are connected in a manner capable of transmitting torque.

[0029] As shown in Fig. 3, when the first face spline 51 and the second face spline 52 are engaged with each other, the face splines 51, 52 are moved closer to each other in the axial direction under the action of the tightening force of the bolt member 26 (see Fig. 1). The hatched area in Fig. 3 represents an engagement area X where the convex stripe of one face spline and the concave stripe of the other face spline finally engage with each other. In the following, the engagement area X provided on one of the face splines will be described. A surface 55 including the tip of each protrusion is referred to as a "tooth tip surface," a region including an outer diameter end of the tooth tip surface 55 in the meshing region X is referred to as an outer diameter portion Ea, a region including an inner diameter end of the tooth tip surface 55 in the meshing region X is referred to as an inner diameter portion Ec, and a region sandwiched between the outer diameter portion Ea and the inner diameter portion Ec is referred to as an intermediate portion Eb.

[0030] In this embodiment, the shapes of the tooth flanks of both face splines 51, 52 are determined so that in the process of bringing the first face spline 51 and the second face spline 52 closer to each other in the axial direction and meshing with each other, the tooth flanks of both face splines 51, 52 first come into contact with each other at the intermediate portion Eb.

[0031] This will be specifically described with reference to FIG. 4. In FIG. 4, rows I to III are 4 shows a time series of the meshing process of the splines 51, 52, where column I shows the initial stage of meshing, column II shows the intermediate stage, and column III shows the final stage. Also, in Fig. 4, row A shows the cross-sectional shape of the outer diameter portion Ea, row B shows the cross-sectional shape of the intermediate portion Eb, and row C shows the cross-sectional shape of the inner diameter portion Ec.

[0032] As shown in Fig. 4, at the intermediate portion Eb (IB) in the initial stage of the meshing process, the tooth surface 51a of the first face spline 51 and the tooth surface 52a of the second face spline 52 come into contact with each other. At this time, there is a gap δ between the tooth surfaces 51a, 52a at the outer diameter portion Ea (IA) and the inner diameter portion Ec (IC). The depth from the tooth tip surface 55 to the portion of the tooth surface that first comes into contact with the mating tooth surface is called the contact start depth. Lb in Fig. 4 indicates the contact start depth at the intermediate portion Eb.

[0033] When the meshing process progresses to the intermediate stage (II row), the tooth surfaces 51a, 52a also contact each other at the outer diameter portion Ea (II-A) and the inner diameter portion Ec (II-C). The contact start depth La at the outer diameter portion Ea and the contact start depth Lc at the inner diameter portion Ec are deeper than the contact start depth Lb at the intermediate portion Eb. After that, the meshing process further progresses to the final stage (III row). After the tooth surfaces 51a, 52a contact each other, the tooth surfaces 51a, 52a are elastically deformed at all parts of the outer diameter portion Ea, the intermediate portion Eb, and the inner diameter portion Ec until the final stage (III row), and the contact state of both the tooth surfaces 51a, 52a is maintained. At this time, the elastic deformation amount of the tooth surfaces 51a, 52b at the intermediate portion Eb, which first contacts, is larger than the elastic deformation amount at other places (outer diameter portion Ea, inner diameter portion Eb).

[0034] 3, the inner diameter end of the tooth tip surface 55 in the meshing region X is 0%, and the outer diameter end is 100%, and it is preferable to set an area of ​​50% or more, specifically an area of ​​50 to 90%, as the intermediate portion Eb where the tooth surfaces first come into contact with each other. By setting an area of ​​50% or more as the intermediate portion Eb, the contact area Y (see FIG. 9(b)) between the tooth surfaces during torque transmission is generally formed on the outer diameter side, so that the load capacity during torque transmission can be increased.

[0035] The above-mentioned contact order can be realized, for example, by determining the shape of the tooth surface 51a so that the tooth surface distance (tooth width) of the convex rib 53 of one face spline (for example, the first face spline 51) is greater than the tooth surface distance of the ideal contour (shown by the two-dot chain line) at the intermediate portion Eb, as shown in Fig. 5. Note that Fig. 5 shows a case where the concave rib 54 that meshes with the convex rib 53 is formed with the ideal contour (shown by the broken line), but the same effect can also be realized by determining the shape of the tooth surface 52a so that the tooth surface distance (tooth gap width) of the concave rib 54 of the other face spline (for example, the second face spline 52) is smaller than the tooth surface distance of the ideal contour at the intermediate portion Eb. These may be combined to increase the tooth surface distance of the convex rib 53 and decrease the tooth surface distance of the concave rib 54 at the intermediate portion Eb. The ideal profile here means an ideal tooth profile free from machining errors such that the tooth surfaces 51a, 52a of both face splines 51, 52 contact each other simultaneously over the entire radial area of ​​the meshing region X.

[0036] In Fig. 5, the distance between the tooth flanks at the intermediate portion Eb is exaggerated for ease of understanding, but the actual amount of enlargement exceeds the maximum processing error that can occur on the tooth flanks 51a and 51b, and is difficult to distinguish with the naked eye. The symbol O in Fig. 5 represents the center of rotation of the wheel bearing device 1.

[0037] FIG. 6(a) shows the contact start depths La, Lb, and Lc of the tooth flanks 51a, 52a when the tooth flanks of both face splines 51, 52 are formed with ideal contours, using dashed lines. In this case, the tooth flanks 51a, 52a contact each other simultaneously over the entire radial area of ​​the meshing area X, so the contact start depth is uniform in the radial direction. Therefore, as shown in FIG. 6(b), the width of the contact area Y (shown by hatching) between the tooth flanks during torque transmission does not change in the radial direction and is constant. On the other hand, since machining errors are unavoidable, it is difficult to realize such a uniform contact start depth and a contact area of ​​uniform width.

[0038] 7(a)(b) show the contact start depths La, Lb, and Lc and the contact area Y when the tooth surfaces are brought into contact with each other from the outer diameter portion Ea as described in Patent Document 2. In this case, the contact area gradually expands toward the inner diameter side after the outer diameter ends of the meshing areas contact, so that the contact area Y between the tooth surfaces 51a, 52a during torque transmission is wide on the outer diameter side and narrow on the inner diameter side, as shown in FIG. 7(b). Therefore, when a bending moment occurs when the constant velocity universal joint 3 takes an operating angle to transmit torque, the contact area Y on the outer diameter side disappears in a part of the circumferential direction of the torque transmission part 50 (the area where the mountain fold occurs), and the total area of ​​the contact area Y is greatly reduced, so that the tooth surfaces 51a, 52a are likely to disengage from each other. Therefore, the bending rigidity of the wheel bearing device 1 is reduced.

[0039] 8(a) and 8(b) show the contact start depths La, Lb, and Lc and the contact area Y when the tooth flanks are brought into contact with each other from the inner diameter portion Ec as described in Patent Document 3. In this case, the contact area gradually expands toward the outer diameter side after the inner diameter ends of the meshing areas come into contact, so that the contact area Y between the tooth flanks 51a and 52a during torque transmission is wider on the inner diameter side and narrower on the outer diameter side, as shown in Fig. 8(b). In this case, the rotation radius of the contact area Y becomes smaller, and the load capacity during torque transmission in the wheel bearing device 1 becomes insufficient.

[0040] 9(a)(b) show the contact start depths La, Lb, and Lc and the contact area Y when the tooth surfaces are brought into contact with each other from the middle part Eb as in this embodiment. In this case, the contact area gradually expands from the middle part Eb of the meshing area toward the outer diameter side and the inner diameter side. In this case, during torque transmission, a wide area including the middle part Eb becomes the contact area Y. Therefore, even if a bending moment acts on the torque transmission part 50 when the constant velocity universal joint 3 takes an operating angle to transmit torque, the total area of ​​the contact area Y does not decrease extremely, and it is possible to prevent the tooth surfaces from coming out of mesh with each other. In addition, since the rotation radius of the contact area Y is generally large, it is possible to ensure a sufficient load capacity during torque transmission. Therefore, it is possible to provide a wheel bearing device 1 having high bending rigidity and high load capacity during torque transmission.

[0041] In addition, it is preferable to determine the shape of each tooth surface 51a, 52a so that after the tooth surfaces at the intermediate portion Eb come into contact with each other, the tooth surfaces 51a, 52a come into contact at the outer diameter portion Ea before the tooth surfaces come into contact at the inner diameter portion Ec. This allows the contact area Y during torque transmission to expand in the outer diameter direction, thereby further increasing the load capacity during torque transmission.

[0042] The present invention is not limited to the above embodiment. Other embodiments of the present invention will be described below, but the description of the same points as the above embodiment will be omitted.

[0043] In the embodiment described above, the second face spline 52 on the bearing 2 side is provided on the end face of the crimped portion 22 of the hub wheel 16, but when using a wheel bearing 2 that does not have the crimped portion 22, the second face spline 52 can also be formed on the outboard end face of the inner ring 17. In this case, it is desirable to provide a rotation stopper such as a serration between the inner ring 17 and the hub wheel 16 to connect them so that torque can be transmitted between them.

[0044] In the above-described embodiment, the mechanism for applying an axial tightening force between the hub wheel 16 and the outer joint member 31 is exemplified by providing the outer joint member 31 with a female threaded portion 38, and axially engaging a member (bolt member 26) having a male threaded portion that screws into this female threaded portion 38 with the hub wheel 16. However, the structure for applying the tightening force is arbitrary, and aside from the above, for example, the outer joint member 31 can be provided with a male threaded portion 27, and a member (for example, a nut member) having a female threaded portion that screws into this male threaded portion can be engaged with the hub wheel 16 in the axial direction to apply the tightening force. [Explanation of symbols]

[0045] 1 Wheel bearing device 2. Wheel bearings 3 Constant velocity universal joint 5,6 Inner raceway surface 7 Inner member 10,11 Outer raceway 12 Outer member 13 Rolling elements 16 Hub wheel 17 Inner Circle 18 Flange 26 Bolt parts 31 Outer joint member 51 First Face Spline 51a Tooth surface 52 Second Face Spline 52a Tooth surface Ea Outer diameter Eb middle part Ec Inner diameter

Claims

1. a wheel bearing including an inner member having a double row inner raceway surface and a flange portion for mounting to a wheel, an outer member having a double row outer raceway surface, and a plurality of rolling elements disposed between the opposing inner raceway surface and outer raceway surface; a constant velocity universal joint having an outer joint member, a bearing device for a wheel, the outer joint member and the inner member being coupled to each other so as to be capable of transmitting torque by engaging face splines provided on the outer joint member and applying an axial tightening force between both face splines, the both face splines having tooth surfaces between tooth tips and tooth bottoms, in a process of bringing both face splines closer to each other in the axial direction and engaging them with each other, among a radial region including an outer diameter end of a tooth tip surface of an engagement region of both face splines, and a region sandwiched between the radial region including the outer diameter end and the radial region including the inner diameter end, the tooth flank shapes of both face splines are determined so that the tooth flanks of both face splines first come into contact with each other in a region sandwiched between the radial region including the outer diameter end and the radial region including the inner diameter end, among a radial region including an inner diameter end of a tooth tip surface of an engagement region of both face splines, the radial region being located on the inner diameter side of the radial region and separated from the radial region and sandwiched between the radial region including the outer diameter end and the radial region including the inner diameter end, the tooth flanks come into contact with each other in a region sandwiched between a radial region including the outer diameter end and a radial region including the inner diameter end, and then the tooth flanks come into contact with each other in a radial region including the outer diameter end and a radial region including the inner diameter end, A wheel bearing device characterized in that when the tooth flanks come into contact with each other, the tooth flanks come into contact with each other on both sides of the teeth of one of the face splines.

2. A wheel bearing device as described in claim 1, wherein the tooth surface shapes of both face splines are determined so that, following the region sandwiched between the radial region including the outer diameter end and the radial region including the inner diameter end, the tooth surfaces of both face splines come into contact with each other in the radial region including the outer diameter end, and then the tooth surfaces of both face splines come into contact with each other in the radial region including the inner diameter end.

3. 3. A wheel bearing device according to claim 1 or 2, wherein, of the meshing regions between the two face splines, an inner diameter end of a tooth tip surface of one of the face splines is defined as 0%, an outer diameter end is defined as 100%, and a region of 50% to 90% is defined as a region sandwiched between a radial region including the outer diameter end and a radial region including the inner diameter end.

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