Wheel drive unit and assembly method thereof

Abstract

To obtain a structure of a hub unit bearing which can improve the assembling performance of a cap.SOLUTION: A cap 7 gripped between a hub 5 and a constant velocity joint 2 in an axial direction has a substantially-L shaped cross section shape, and is constituted into a circular ring shape as a whole. The cap 7 includes a circular ring flat-plate shaped baseboard part 25, a covering cylinder part 26 extending toward the outside in the axial direction from an end part of the outside of the baseboard part 25 in a radial direction, and covering a caulking part 18 from the outside in the radial direction, and a lock part 27 extending toward the inside in the radial direction from an end part of the covering cylinder part 26 at the outside in the axial direction. The smallest diameter part being a portion whose inside diameter is smallest in the lock part 27 is arranged at the outside in the axial direction with respect to the largest diameter part being a portion whose outside diameter is largest in the caulking part 18, and the cap has an inside diameter larger than an outside diameter of the largest diameter part of the caulking part 18.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to Wheel drive unit and assembly method thereof Regarding. [Background technology]

[0002] The wheels and braking rotors of an automobile are rotatably supported by a suspension system through a hub unit bearing. Figures 7 and 8 show a hub unit bearing 100, an example of a conventional structure, described in JP 2008-296841 A (Patent Document 1).

[0003] The hub unit bearing 100 is a hub unit bearing for a driving wheel that rotatably supports the driving wheel, and is used in combination with a constant velocity joint (CVJ) 101.

[0004] The hub unit bearing 100 includes an outer ring 102 that does not rotate when in use, a hub 103 that rotates when in use, and a plurality of rolling elements 104. With regard to the hub unit bearing 100 and its surrounding components, the axially outer side is the left side in Figures 7 and 8, which is the outer side in the width direction of the vehicle when assembled to the vehicle, and the axially inner side is the right side in Figures 7 and 8, which is the central side in the width direction of the vehicle when assembled to the vehicle.

[0005] The outer ring 102 has double-row outer ring raceways 105a, 105b on its inner circumferential surface. The outer ring 102 has a stationary flange 106 at the axially middle portion of its outer circumferential surface for supporting and fixing the outer ring 102 to a suspension device (not shown).

[0006] Hub 103 is disposed radially inside outer ring 102 and coaxially therewith, and is formed by combining hub ring 107 and inner ring 108. Hub 103 has double row inner ring raceways 109a, 109b on the outer circumferential surface thereof that face double row outer ring raceways 105a, 105b.

[0007] Hub wheel 107 is a shaft member that fits around and holds inner wheel 108, and has a shaft portion 110 and a rotating flange 111. Since hub unit bearing 100 is for a drive wheel, hub wheel 107 has a spline hole 112 in the radial center for splined engagement with spline shaft portion 117 that constitutes constant velocity joint 101.

[0008] The shaft portion 110 is provided in a range extending from the axially inner portion to the axially intermediate portion of the hub wheel 107. The shaft portion 110 has a crimping portion 113 at its axially inner end portion for pressing the axially inner end face of the inner ring 108, and a small diameter portion 114 for externally fitting the inner ring 108 at a portion adjacent to the axially outer side of the crimping portion 113. The shaft portion 110 has a step surface 115 facing axially inward at a portion adjacent to the axially outer side of the small diameter portion 114, and has an inner ring raceway 109a in the axially outer row on the outer peripheral surface at the axially intermediate portion.

[0009] The rotating flange 111 is provided on a portion of the hub wheel 107 that is positioned axially outward of the axially outer end of the outer ring 102, and has a generally circular ring shape. The driving wheel and the braking rotor are connected and fixed to the rotating flange 111 using a plurality of studs 116.

[0010] The inner ring 108 has an inner ring raceway 109b in the axially inner row on its outer circumferential surface. The inner ring 108 is fitted onto the small diameter portion 114 of the hub ring 107, and is axially sandwiched between the stepped surface 115 and the crimped portion 113. This prevents the inner ring 108 from being separated from the hub ring 107.

[0011] The constant velocity joint 101 has a splined shaft portion 117 and an outer ring 118 for a joint.

[0012] The splined shaft portion 117 is inserted from the axially inner side into a splined hole 112 provided in the hub 103, and is spline-engaged with the splined hole 112 so as to be capable of transmitting torque. A nut 119 is screwed onto the tip end of the splined shaft portion 117. This connects the hub unit bearing 100 and the constant velocity joint 101.

[0013] The joint outer ring 118 is configured in a cylindrical shape with a bottom that is open on the axially inner side, and is provided integrally with the spline shaft portion 117 on the axially inner side of the spline shaft portion 117 .

[0014] In the hub unit bearing 100 of the conventional structure described in JP 2008-296841 A, the axial distance L (see FIG. 7) from the axially inner end of the spline hole 112 to the axially inner end face of the crimped portion 113 is relatively large. For this reason, when a large torque is input to the constant velocity joint 101, the spline shaft portion 117 is likely to twist. For this reason, when the axially inner end face of the crimped portion 113 and the axially outer end face of the joint outer ring 118 are brought into direct contact with each other, a stick-slip phenomenon (slip between metal surfaces) occurs between the axially inner end face of the crimped portion 113 and the axially outer end face of the joint outer ring 118, which may cause an abnormal noise called a stick-slip noise.

[0015] Therefore, in the conventional hub unit bearing 100 described in JP 2008-296841 A, a cap 120 is interposed between the axially inner end face of the crimping portion 113 and the axially outer end face of the joint outer ring 118.

[0016] Cap 120 is made of a metal plate and has a low surface roughness. Therefore, when a large torque is input to constant velocity joint 101, either crimped portion 113 or joint outer ring 118 can rotate relative to cap 120 before a large amount of energy accumulates between crimped portion 113 and joint outer ring 118. Therefore, abnormal noise can be prevented from occurring between crimped portion 113 and joint outer ring 118. [Prior art documents] [Patent documents]

[0017] [Patent Document 1] JP 2008-296841 A [Patent Document 2] JP 2015-77616 A Summary of the Invention [Problem to be solved by the invention]

[0018] However, in the hub unit bearing 100 of the conventional structure described in JP 2008-296841 A, in order to prevent the cap 120 from falling off the hub unit bearing 100, the shape and dimensions of the cap 120 are regulated as follows.

[0019] That is, as shown in Fig. 8, a locking portion 121 extending radially inward is provided at the axially outer end of cap 120, and this locking portion 121 is disposed axially outward of maximum diameter portion P, which is the largest outer diameter portion of crimped portion 113. Also, the inner diameter of locking portion 121 is made smaller than the outer diameter of maximum diameter portion P of crimped portion 113. In this manner, in the conventional structure described in JP 2008-296841 A, locking portion 121 is locked to crimped portion 113 with a tightening margin.

[0020] However, as disclosed in, for example, JP 2015-77616 A (Patent Document 2), the crimped portion is formed by pressing the axially inner end face of the crimped portion with a die without restraining the outer peripheral surface of the crimped portion. Therefore, the crimped portion is formed such that the volume variation that is unavoidable in the process is released to the outer peripheral surface of the crimped portion. Therefore, the outer diameter of the crimped portion varies greatly.

[0021] For this reason, when locking portion 121 is locked to crimped portion 113 with a tightening margin as in the conventional structure described in JP 2008-296841 A, it is necessary to set the inner diameter of locking portion 121 sufficiently small in consideration of the variation in the outer diameter of the crimped portion. As a result, when cap 120 is assembled to crimped portion 113, interference between locking portion 121 and crimped portion 113 becomes large, and the assembly of cap 120 becomes difficult.

[0022] The present invention has been made to solve the above problems, and is capable of improving the ease of assembly of a cap. Wheel drive unit and assembly method thereof The purpose is to provide. [Means for solving the problem]

[0023] According to one aspect of the present invention Wheel drive unit teeth, The vehicle includes a hub unit bearing and a constant velocity joint. The hub unit bearing is It comprises an outer ring, a hub, a plurality of rolling elements, and a cap. The outer ring has a double row outer ring raceway on its inner circumferential surface. The hub has a double row inner ring raceway on its outer circumferential surface, The above It is rotated by a constant velocity joint. The rolling elements are arranged between the double row outer ring raceways and the double row inner ring raceways, with a plurality of rolling elements arranged for each row. The cap is axially sandwiched between the hub and the constant velocity joint. The hub includes a hub wheel and an inner ring that is fitted onto the hub wheel and has, on its outer circumferential surface, an inner ring raceway that is an axially inner row of the double row inner ring raceways. The hub wheel has a crimping portion that presses against an axially inner end face of the inner ring. The cap has an approximately J-shaped cross-sectional shape and is generally annular in shape, and is composed of a circular flat base portion arranged axially inside the crimping portion, a covering tubular portion extending axially outward from the radially outer end of the base portion and covering the crimping portion from the radially outer side, a locking portion extending radially inward from the axially outer end of the covering tubular portion, and a drainage hole that passes through the cap. With the base plate portion sandwiched between the crimping portion and the constant velocity joint, The minimum diameter portion, which is the portion of the locking portion having the smallest inner diameter, is disposed axially outward of the maximum diameter portion, which is the portion of the crimping portion having the largest outer diameter, and has an inner diameter larger than the outer diameter of the maximum diameter portion. The central axis of the cap is eccentric with respect to the central axis of the hub, and only a circumferential portion of the locking portion overlaps with the crimped portion in the axial direction.

[0024] The present invention Wheel drive unitIn one aspect, the portion of the cap including at least the engagement portion can be configured in a comb-tooth shape consisting of a plurality of strip-shaped pieces spaced apart in the circumferential direction, and the drainage hole can be provided in the portion between adjacent strip-shaped pieces in the circumferential direction.

[0025] The present invention Wheel drive unit In one aspect, at least a portion of the engaging portion including the minimum diameter portion can be made of an elastic material. In this case, the entire engaging portion may be made of an elastic material.

[0026] The present invention Wheel drive unit In one aspect, the drain hole may be provided at a radially outer end of the cap. The present invention Wheel drive unit In one aspect, the drainage hole may be provided in the cover tube portion. Alternatively, the drainage hole may be provided in the locking portion or the base portion. When the drainage hole is provided in the base plate portion, the drainage hole can be formed so as to penetrate the base plate portion in the axial direction.

[0027] A method of assembling a wheel drive unit according to one embodiment of the present invention includes the steps of axially inserting the crimped portion into the inside of the cap before the hub unit bearing and the constant velocity joint are assembled, positioning the entire locking portion axially outwardly of the maximum diameter portion of the crimped portion, and then eccentrically aligning the central axis of the cap and the central axis of the hub to axially overlap a portion of the locking portion with respect to the crimped portion. Effect of the Invention

[0028] According to the present invention, the ease of assembly of the cap can be improved. Wheel drive unit The structure can be realized. [Brief description of the drawings]

[0029] [Figure 1] FIG. 1 is a cross-sectional view showing a wheel drive unit according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is an enlarged view of part A in FIG. [Diagram 3] 3A to 3C are cross-sectional views showing the process of assembling the cap to the crimped portion. [Figure 4] FIG. 4 is a diagram showing a second embodiment of the present invention, and corresponds to FIG. [Diagram 5] FIG. 5 is a perspective view showing a part of a cap according to a second example of the embodiment. [Figure 6] FIG. 6 is a diagram showing a third example of the embodiment, and corresponds to FIG. [Figure 7] FIG. 7 is a cross-sectional view showing an example of a wheel drive unit having a conventional structure. [Figure 8] FIG. 8 is an enlarged view of part B in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] [First Example of Implementation] A first example of the embodiment will be described with reference to FIGS. 1 to 3. FIG.

[0031] The hub unit bearing 1 of this example is combined with a constant velocity joint (CVJ) 2 to form a wheel drive unit 3. The wheel drive unit 3 supports drive wheels for an independent suspension and drives the drive wheels to rotate. The drive wheels correspond to the front wheels of FF vehicles, the rear wheels of FR and RR vehicles, and the wheels of 4WD vehicles.

[0032] <Hub unit bearing> The hub unit bearing 1 is an inner ring rotating type, a so-called third generation hub unit bearing for a driving wheel, and includes an outer ring 4, a hub 5, a plurality of rolling elements 6, and a cap . With regard to the hub unit bearing 1 and its surrounding components, the axially outer side is the left side in Figures 1 to 3, which is the outer side in the width direction of the vehicle when assembled to the vehicle, and the axially inner side is the right side in Figures 1 to 3, which is the central side in the width direction of the vehicle when assembled to the vehicle.

[0033] Paddle Wheel The outer ring 4 has a substantially cylindrical shape. The outer ring 4 has double-row outer ring raceways 8a, 8b on its inner circumferential surface, and a stationary flange 9 protruding radially outward at the axially middle portion of its outer circumferential surface. The stationary flange 9 has support holes 10 penetrating in the axial direction at multiple locations in the circumferential direction. The outer ring 4 is supported and fixed to the suspension device by bolts inserted into the support holes 10. Therefore, the outer ring 4 does not rotate even when the wheel drive unit 3 is in use. The outer ring 4 is made of medium carbon steel such as S53C, and a hardening process such as induction hardening is performed on the area including the outer ring raceways 8a, 8b.

[0034] Hub The hub 5 is disposed radially inside the outer ring 4 and coaxially therewith, and is formed by combining a hub ring 11 and an inner ring 12. The hub 5 has double row inner ring raceways 13a, 13b on the outer circumferential surface thereof that face the double row outer ring raceways 8a, 8b.

[0035] The hub ring 11 is a shaft member that fits and holds the inner ring 12, and has a shaft portion 14, a rotating flange 15, and a pilot portion 16. As the hub unit bearing 1 of this example is for a drive wheel, the hub ring 11 is hollow and has a spline hole 17 in the center. The spline hole 17 passes through the center of the hub ring 11 in the axial direction. The hub ring 11 is made of medium carbon steel such as S53C, and the outer peripheral surface of the shaft portion 14, including the inner ring raceway 13a in the axially outer row, has been subjected to a hardening process such as induction hardening.

[0036] The shaft portion 14 is provided in a range extending from the axially inner portion to the axially intermediate portion of the hub wheel 11. The shaft portion 14 has a crimping portion 18 at its axially inner end portion for pressing the axially inner end face of the inner ring 12, and a small diameter portion 19 for externally fitting the inner ring 12 at a portion adjacent to the axially outer side of the crimping portion 18. The shaft portion 14 has a step surface 20 facing axially inward at a portion adjacent to the axially outer side of the small diameter portion 19, and has an inner ring raceway 13a in the axially outer row on the outer peripheral surface at the axially intermediate portion.

[0037] The crimped portion 18 is formed by swinging and pressing, for example, in the same manner as in the method described in JP 2015-77616 A. That is, the cylindrical portion of the axially inner end of the shaft portion 14, which is the crimped portion forming portion and which protrudes axially inward from the inner ring 12, is pressed while the die is oscillated. Then, the tip of the cylindrical portion is crimped radially outward and expanded (plastically deformed) to form the crimped portion 18. Therefore, in this example, the crimped portion 18 is formed without restraining the outer circumferential surface. Therefore, the outer circumferential surface of the crimped portion 18 is free from volume variations that are unavoidable in processing. In addition, the end surface of the crimped portion 18 on the axially inner side is a flat surface that exists on a virtual plane perpendicular to the central axis of the hub 5.

[0038] The rotating flange 15 is provided on a portion of the hub wheel 11 that is located axially outward of the axially outer end of the outer ring 4, and has a generally circular ring shape. The rotating flange 15 has mounting holes 21 penetrating in the axial direction at a plurality of circumferential positions in a radially intermediate portion. Studs 22 are press-fitted into each of the mounting holes 21. Nuts (not shown) are screwed into the tips of the studs 22. This fixes the wheel and braking rotor that constitute the wheel (drive wheel) to the axially outer side of the rotating flange 15. Therefore, the hub 5 rotates when the wheel drive unit 3 is in use. When carrying out the present invention, a female screw hole may be formed in the rotating flange, and a hub bolt may be directly screwed into the female screw hole to fix the wheel and braking rotor to the axially outer side of the rotating flange.

[0039] The pilot portion 16 is provided at the axially outer end of the hub wheel 11 so that the wheel and the braking rotor are fitted thereto with a clearance fit without any rattle, and has a generally cylindrical shape.

[0040] The inner ring 12 has an annular shape and has an inner ring raceway 13b in the axially inner row at the axially middle portion of the outer circumferential surface. The inner ring 12 is fitted onto a small diameter portion 19 of the shaft portion 14 by interference fit. The inner ring 12 is made of high carbon chromium bearing steel such as SUJ2, and is subjected to heat treatment such as quenching and tempering. The axially inner end face of the inner ring 12 is a flat surface existing on a virtual plane perpendicular to the central axis of the inner ring 12, and is pressed by a crimping portion 18 provided on the shaft portion 14. As a result, the inner ring 12 is sandwiched in the axial direction between the step surface 20 and the crimping portion 18. This prevents the inner ring 12 from being separated from the hub ring 11.

[0041] Rolling Body The rolling elements 6 are made of high carbon chromium steel or ceramic, and are arranged between the double row outer ring raceways 8a, 8b and the double row inner ring raceways 13a, 13b, with a plurality of rolling elements for each row at equal intervals in the circumferential direction, and are held by a cage 23 so as to be freely rollable. As a result, the hub 5 is supported so as to be freely rotatable on the radial inside of the outer ring 4. In this example, balls are used as the rolling elements 6, but tapered rollers can also be used instead of balls. In addition, in this example, the pitch circle diameter of the rolling elements 6 in the axially inner row and the pitch circle diameter of the rolling elements 6 in the axially outer row are the same, but the present invention can also be applied to a different diameter PCD type hub unit bearing in which the pitch circle diameter of the rolling elements in the axially inner row and the pitch circle diameter of the rolling elements in the axially outer row are different from each other.

[0042] Grease (not shown) is sealed in an annular internal space that exists between the inner peripheral surface of the outer ring 4 and the outer peripheral surface of the hub 5 and in which a number of rolling elements 6 are installed. To prevent the grease sealed in the internal space from leaking into the external space and to prevent foreign matter such as muddy water from entering the internal space from the external space, openings on both axial sides of the internal space are sealed by a pair of sealing devices 24a, 24b.

[0043] "cap" Cap 7 is held in the axial direction between crimped portion 18 provided on the axially inner end of shaft portion 14 that constitutes hub 5 and a joint outer ring 30 (described below) that constitutes constant velocity joint 2, preventing the generation of abnormal noise known as stick-slip noise. Cap 7 has a structure that allows it to engage with crimped portion 18 of hub unit bearing 1 before the hub unit bearing 1 and constant velocity joint 2 are joined.

[0044] The cap 7 is made by pressing a corrosion-resistant metal plate, such as a rust-proofed cold-rolled steel plate or an austenitic stainless steel plate. The cap 7 has a substantially J-shaped cross section and is configured to be annular as a whole. The cap 7 in this example is entirely made of metal.

[0045] As shown in FIG. 2, the cap 7 includes a base portion 25, a cylindrical cover portion 26, and a locking portion 27.

[0046] The surface roughness of at least the portion of the cap 7 that includes the substrate 25 is set to Ra 0.7 or less, and preferably 0.3 or less. A coating layer (low friction coating) such as molybdenum disulfide or polytetrafluoroethylene (PTFE) can also be formed on the portion of the cap 7 that includes the surface of the substrate 25.

[0047] The base plate portion 25 is configured in the shape of an annular flat plate, and is disposed axially inside the crimped portion 18. With the hub unit bearing 1 and the constant velocity joint 2 joined together, the base plate portion 25 is axially sandwiched between the axially inside end face of the crimped portion 18 and the axially outside end face of the joint outer ring 30. The inner diameter of the base plate portion 25 is sufficiently larger than the outer diameter of a spline shaft portion 29, which will be described later. The outer diameter of the base plate portion 25 is the outer diameter D at a maximum diameter portion P of the crimped portion 18, which is the largest outer diameter of the crimped portion 18. 18 Just a little bigger than.

[0048] The covering tube portion 26 extends from the radially outer end of the base portion 25 toward the axially outer side, and covers the crimping portion 18 from the radially outer side. The covering tube portion 26 is configured in a cylindrical shape. The axial dimension of the covering tube portion 26 is larger than the axial dimension from the axially inner end face of the crimping portion 18 to the maximum diameter portion P.

[0049] The locking portion 27 is configured in an inward flange shape, extends radially inward from the axially outer end of the covering tube portion 26, and is disposed approximately parallel to the base plate portion 25. The locking portion 27 has a circular ring shape when viewed in the axial direction, and has a cylindrical inner circumferential surface (inner peripheral edge). Therefore, the inner diameter of the locking portion 27 is constant along the axial direction. Therefore, any axial position on the inner circumferential surface of the locking portion 27 corresponds to a minimum diameter portion Q of the locking portion 27, which has the smallest inner diameter.

[0050] In this embodiment, the entire locking portion 27 is disposed axially outward from the maximum diameter portion P of the crimped portion 18, so that the minimum diameter portion Q of the locking portion 27 is disposed axially outward from the maximum diameter portion P of the crimped portion 18. In addition, the inner diameter d 27 The outer diameter D of the maximum diameter portion P of the crimped portion 18 18 It is slightly larger than (d 27 >D 18 More specifically, the inner diameter d of the smallest diameter portion Q of the locking portion 27 27 is set to be larger than the outer diameter at maximum diameter part P of crimped portion 18 even if the outer diameter of crimped portion 18 varies. For this reason, as shown in Fig. 2, when hub unit bearing 1 and constant velocity joint 2 are combined and the central axis of hub 5 and the central axis of cap 7 are arranged coaxially with each other, the inner circumferential surface (minimum diameter part Q) of locking portion 27 is located radially outward of maximum diameter part P of crimped portion 18.

[0051] The cap 7 has drainage holes 28 penetrating the cap 7 at its radially outer end. In this example, the drainage holes 28 are formed in the covering tubular portion 26 located at the radially outer end of the cap 7. The drainage holes 28 penetrate the covering tubular portion 26 in the radial direction, and open to both the inner and outer circumferential surfaces of the covering tubular portion 26. The drainage holes 28 are provided at multiple locations on the covering tubular portion 26 at equal intervals in the circumferential direction.

[0052] The cap 7 of this example is attached to the crimped portion 18 of the hub unit bearing 1 before the hub unit bearing 1 and the constant velocity joint 2 are assembled. That is, as shown in FIG. 3(A), the central axis O of the cap 7 is 7 and the central axis O of the hub 5 5 With these positioned approximately coaxially and horizontally, the crimped portion 18 is inserted axially inside the cap 7, and the entire locking portion 27 is positioned axially outward of the maximum diameter portion P of the crimped portion 18. Then, as shown in FIG. 3(B), the force supporting the cap 7 is reduced (finally reduced to zero), causing the cap 7 to move vertically downward by gravity, and the central axis O of the cap 7 is aligned with the center axis P of the cap 7. 7 , the central axis O of the hub 5 5 As a result, the portion of locking portion 27 located on the upper side in the vertical direction (approximately the upper half) is overlapped in the axial direction with crimping portion 18 and locked to crimping portion 18.

[0053] As described above, in this example, before the hub unit bearing 1 and constant velocity joint 2 are assembled, a portion (approximately the upper half) of locking portion 27 that constitutes cap 7 is locked to crimped portion 18 of hub unit bearing 1. This ensures a locking force that is sufficient to prevent cap 7 from falling off crimped portion 18 when transporting hub unit bearing 1 with cap 7 attached, or when installing hub unit bearing 1 into the vehicle body.

[0054] In addition, when carrying out the present invention, when assembling the cap 7 to the crimping portion 18, it is also possible to apply grease to at least one of the base plate portion 25 and the crimping portion 18, and thereby affix the base plate portion 25 and the crimping portion 18 with the grease. By affixing the base plate portion 25 and the crimping portion 18 in this manner, it is possible to more effectively prevent the cap 7 from falling off.

[0055] <Constant velocity joint> As shown in FIG. 1, the constant velocity joint 2 includes a spline shaft portion 29, a joint outer ring 30, a joint inner ring 31, and a plurality of balls 32.

[0056] The splined shaft portion 29 is inserted into the splined hole 17 provided in the hub 5 from the inside in the axial direction, and is spline-engaged so as to be able to transmit torque to the splined hole 17. The splined shaft portion 29 has a male thread portion 33 on the outer circumferential surface of the tip portion (the end portion on the outer axial direction).

[0057] The outer ring 30 for a joint is made of medium carbon steel that has been subjected to thermal treatment, and is configured as a bottomed cylinder (cup-shaped) that is open on the axially inner side, and is provided integrally with the splined shaft portion 29 on the axially inner side of the splined shaft portion 29. The outer ring 30 for a joint is provided with outer engagement grooves 34 at multiple locations in the circumferential direction on the inner peripheral surface of the outer ring 30 for a joint. The outer engagement grooves 34 extend in a direction perpendicular to the circumferential direction of the outer ring 30 for a joint. The outer ring 30 for a joint has a bottom 35 at its axially outer end. The axially inner end of the splined shaft portion 29 is connected to the radial center of the axially outer surface of the bottom 35. The radially outer portion of the axially outer surface of the bottom 35 (shoulder of the outer ring 30 for a joint) is a flat surface that exists on an imaginary plane perpendicular to the central axis of the outer ring 30 for a joint.

[0058] The joint inner ring 31 is configured in an annular shape and is fitted onto the axially outer end of a drive shaft 36 that is driven to rotate by a drive source such as an engine so as to be non-rotatable relative to the drive shaft 36. The joint inner ring 31 is provided with inner engagement grooves 37 at multiple locations in the circumferential direction on its outer circumferential surface. The inner engagement grooves 37 extend in a direction perpendicular to the circumferential direction of the joint inner ring 31.

[0059] The balls 32 are disposed between the outer engagement groove 34 and the inner engagement groove 37, one each, so as to be able to roll along the outer engagement groove 34 and the inner engagement groove 37.

[0060] To connect the hub unit bearing 1 and the constant velocity joint 2, the splined shaft portion 29 is inserted into the splined hole 17 from the inside in the axial direction, and a nut 38 is screwed onto the male thread portion 33 provided at the tip of the splined shaft portion 29. As a result, the base plate portion 25 constituting the cap 7 is sandwiched from both axial sides between the axially inner end face of the crimping portion 18 and the axially outer end face of the joint outer ring 30 (bottom portion 35). Also, by sandwiching the inner ring 12 from both axial sides between the step surface 20 of the hub wheel 11 and the crimping portion 18, a preload is applied to the rolling elements 6.

[0061] In the case of the hub unit bearing 1 of this example as described above, the cap 7 with a low surface roughness is interposed between the axially inner end face of the crimped portion 18 and the axially outer end face of the joint outer ring 30. Therefore, when a large torque is input to the constant velocity joint 2, one of the crimped portion 18 and the joint outer ring 30 can be rotated relative to the cap 7 before a large amount of energy accumulates between the crimped portion 18 and the joint outer ring 30. Therefore, the occurrence of stick-slip noise between the crimped portion 18 and the joint outer ring 30 can be prevented.

[0062] Furthermore, according to the hub unit bearing 1 of this embodiment, the ease of assembling the cap 7 can be improved. That is, in this embodiment, the inner diameter d of the minimum diameter portion Q of the locking portion 27 located axially outward of the maximum diameter portion P of the crimping portion 18 of the cap 7 is 27The outer diameter D of the maximum diameter portion P of the crimped portion 18 18 (d 27 >D 18 ). Therefore, when inserting the crimping portion 18 into the inside of the cap 7 to assemble the cap 7 to the crimping portion 18, there is no interference between the locking portion 27 and the crimping portion 18. This improves the ease of assembly of the cap 7.

[0063] In addition, the inner diameter d of the minimum diameter portion Q of the locking portion 27 27 The outer diameter D of the maximum diameter portion P of the crimped portion 18 18 Even if the central axis O of the cap 7 is larger than 10 mm, as shown in FIG. 7 The central axis of the hub 5 is O 5 With the cap 7 eccentrically disposed vertically downward with respect to the crimping portion 18, the portion of the locking portion 27 located on the upper side in the vertical direction can be locked with the crimping portion 18 with a locking force sufficient to prevent the cap 7 from falling off from the crimping portion 18. Therefore, there is no problem with the cap 7 falling off.

[0064] In addition, since the cap 7 is provided with the drainage holes 28, even if muddy water or other moisture enters the space between the cap 7 and the crimped portion 18, the moisture can be discharged to the outside through the drainage holes 28 by utilizing centrifugal force or gravity. Therefore, rusting of the crimped portion 18 and the cap 7 can be suppressed.

[0065] [Second Example of the Implementation Form] The second embodiment will be described with reference to FIGS.

[0066] In this example, only the structure of the cap 7a is different from the structure of the first example of the embodiment.

[0067] The cap 7a is composed of a base plate portion 25, a cover tube portion 26a, and a locking portion 27a, of which the structure of the base plate portion 25 is the same as that of the first example of the embodiment.

[0068] In this example, the cover tube portion 26a and the locking portion 27a are configured in a comb-tooth shape consisting of a plurality of strip pieces 39 spaced apart in the circumferential direction over the entire circumference. The circumferential width of the strip piece 39 is constant over the entire length of the strip piece 39. The strip piece 39 has a substantially L-shaped cross section and is composed of an axial strip piece 39a extending in the axial direction and a radial strip piece 39b extending radially inward from the axially outer end of the axial strip piece 39a. The cover tube portion 26a is configured to include a plurality of axial strip pieces 39a, and the locking portion 27a is configured to include a plurality of radial strip pieces 39b.

[0069] The radial strip pieces 39b constituting the locking portion 27a are disposed approximately parallel to the base plate portion 25. The radial inner end faces of the radial strip pieces 39b each have a constant inner diameter along the axial direction. For this reason, in the present example as well, any axial position of the inner peripheral surface (the radial inner end faces of the radial strip pieces 39b) of the locking portion 27a corresponds to the minimum diameter portion Q of the locking portion 27a, which has the smallest inner diameter. Therefore, by disposing the entire locking portion 27a axially outward of the maximum diameter portion P, the minimum diameter portion Q of the locking portion 27a is disposed axially outward of the maximum diameter portion P of the crimping portion 18. In addition, the inner diameter d of the minimum diameter portion Q of the locking portion 27a is axially outward of the maximum diameter portion P of the crimping portion 18. 27 The outer diameter D of the maximum diameter portion P of the crimped portion 18 18 (d 27 >D 18 ).

[0070] Slit-shaped drainage holes 28a are provided between circumferentially adjacent strip pieces 39. That is, the drainage holes 28a are provided in the portions between circumferentially adjacent axial strip pieces 39a and between circumferentially adjacent radial strip pieces 39b.

[0071] In this embodiment having the above-mentioned configuration, the strip pieces 39 and the drain holes 28a constituting the cover tube portion 26a and the locking portion 27a can be formed simultaneously when blanking the metal plate. This improves the processing efficiency of the cap 7a. In addition, since the drain holes 28a can be processed using a large die, die wear can be suppressed compared to when the drain holes are processed by punching with a punch. The other configurations and effects are the same as those of the first embodiment.

[0072] As a first example of a modification of this embodiment, only the locking portion constituting the cap can be configured to have a comb-tooth shape. As a second example of the modification, in addition to the locking portion and the cover tube portion constituting the cap, the end portion up to the radially outer end of the base portion can be configured to have a comb-tooth shape. Furthermore, as a third example of the modification, the portion of the cap including at least the locking portion can be configured to have a comb-tooth shape not over the entire circumference but at a portion or multiple points in the circumferential direction.

[0073] [Third Example of the Implementation Form] A third example of the embodiment will be described with reference to FIG.

[0074] In this example, only the structure of the cap 7b is different from the structures of the first and second examples of the embodiment.

[0075] The cap 7b is made up of a core metal 40 made of a metal plate and an elastic member 41 fixed to the core metal 40 and made of an elastic material such as rubber.

[0076] The core bar 40 is made by pressing a corrosion-resistant metal plate. The core bar 40 has a substantially L-shaped cross section and is configured in an overall annular shape.

[0077] The core metal 40 has a base plate portion 25 having an annular flat plate shape, and a tubular main body 42 having a cylindrical shape that extends axially outward from a radially outer end portion of the base plate portion 25 .

[0078] The elastic material 41 is vulcanization molded using a vulcanization mold, and has a covering portion 43 that covers the outer peripheral surface of a tubular body 42 that constitutes the core bar 40, and a locking portion 27b that extends radially inward from an axially outer end of the tubular body 42. The covering portion 43 and the locking portion 27b are provided integrally.

[0079] Therefore, in this example, the cap 7b has a base portion 25 made of a metal plate, the entire engaging portion 27b made of an elastic material, and the covering tube portion 26b is composed of a tube main body 42 made of a metal plate and a covering portion 43 made of an elastic material.

[0080] The inner peripheral surface of the locking portion 27b is configured as a cylindrical surface, and the inner diameter is constant along the axial direction. Therefore, in this example as well, any axial position on the inner peripheral surface of the locking portion 27b corresponds to the minimum diameter portion Q, which has the smallest inner diameter of the locking portion 27b. Therefore, by positioning the entire locking portion 27b axially outward of the maximum diameter portion P, the minimum diameter portion Q of the locking portion 27b is positioned axially outward of the maximum diameter portion P of the crimping portion 18. In addition, the inner diameter d of the minimum diameter portion Q of the locking portion 27b is 27 The outer diameter D of the maximum diameter portion P of the crimped portion 18 18 (d 27 >D 18 In this example, the inner diameter d 27 and the outer diameter D of the maximum diameter portion P of the crimped portion 18 18 The difference between is smaller than in the first and second examples of the embodiment.

[0081] The cap 7b has a drain hole 28b in its radially outer portion. The drain hole 28b is formed in a radially outer portion of the base plate portion 25, located radially outward of the axially inner end face of the crimping portion 18 and the axially outer end face of the joint outer ring 30, when the central axis of the hub 5 and the central axis of the cap 7b are coaxially arranged with each other. The drain hole 28b axially penetrates the base plate portion 25 at multiple points in the circumferential direction, and opens on each of the axially inner surface and the axially outer surface of the base plate portion 25.

[0082] In this embodiment having the above-mentioned configuration, the metal plate is pressed into a substantially L-shaped cross section instead of a substantially J-shaped cross section, so that the press processing device can be made smaller and the shape precision of the base plate portion 25 and the tubular body 42 formed by the press processing can be stabilized. In addition, since the locking portion 27b is made of an elastic material instead of a metal, the locking portion 27b can be elastically deformed when the cap 7b is locked to the crimping portion 18. Therefore, even if the inner diameter of the locking portion 27b (the inner diameter of the minimum diameter portion Q) is made closer to the outer diameter of the maximum diameter portion P of the crimping portion 18, the ease of assembly of the cap 7b can be prevented from being reduced. In addition, by making the inner diameter of the locking portion 27b smaller, the cap 7b can be more effectively prevented from falling off. The other configurations and effects are the same as those of the first embodiment.

[0083] Although the embodiment of the present invention has been described above, the present invention is not limited to this, and can be modified as appropriate without departing from the technical concept of the invention. Furthermore, the structures of the examples of the embodiment can be combined as appropriate as long as no contradiction occurs.

[0084] When implementing the present invention, the number, shape and formation position of the drainage holes are not limited to the structures of the examples of the embodiments, and can be changed as appropriate.

[0085] In addition, when implementing the present invention, the shape of the cap is not limited to the shapes shown in the respective embodiments, and can be changed as appropriate. For example, the covering tube is not limited to a cylindrical shape, and can be changed to other shapes such as a conical tube shape or a curved tube shape.

[0086] Furthermore, the inner peripheral surface of the locking portion is not limited to a cylindrical surface, and may be a shape whose inner diameter changes in the axial direction, such as a tapered surface or a stepped cylindrical surface. When such a configuration is adopted, as long as the minimum diameter portion, which is the portion of the locking portion with the smallest inner diameter, is located axially outward of the maximum diameter portion of the crimping portion, the portions of the locking portion other than the minimum diameter portion may be located axially inward of the maximum diameter portion of the crimping portion.

[0087] In each of the embodiments, a structure has been described in which the inner ring raceways of the axially outer row are formed directly on the outer peripheral surface of the hub ring, but when implementing the present invention, a structure in which an inner ring having the inner ring raceways of the axially outer row on its outer peripheral surface is fitted onto the hub ring can also be adopted. In other words, the hub can be composed of a hub ring and a pair of inner rings each having an inner ring raceway on its outer peripheral surface. [Explanation of symbols]

[0088] 1 Hub unit bearing 2 Constant velocity joint 3 Wheel drive unit 4 Outer ring 5 Hub 6 Rolling elements 7, 7a, 7b Cap 8a, 8b Outer raceway 9 Stationary Flange 10 Support hole 11 Hub wheel 12 Inner Circle 13a, 13b Inner raceway 14 Shaft 15 Rotating flange 16 Pilot Division 17 Spline hole 18 Crimping part 19 Small diameter section 20 Step surface 21 Mounting hole 22 Stud 23 Cage 24a, 24b Sealing device 25 Circuit Board 26, 26a, 26b Covering tube 27, 27a Locking part 28, 28a Drain hole 29 Spline shaft 30 Outer ring for joint 31 Inner ring for joint 32 Ball 33 Male thread 34 Outer engagement groove 35 Bottom 36 Drive shaft 37 Inner engagement groove 38 Nut 39 Strip 39a Axial strip 39b Radial strips 40 Core wire 41 Elastic material 42 Cylinder body 43 Covering section 100 Hub unit bearing 101 Constant velocity joint 102 Outer ring 103 Hub 104 Rolling elements 105a, 105b outer raceway 106 Stationary Flange 107 Hub Wheel 108 Inner Circle 109a, 109b Inner raceway 110 Shaft 111 Rotating flange 112 Spline hole 113 Crimping part 114 Small diameter section 115 Step surface 116 Studs 117 Spline shaft 118 Outer ring for joint 119 Nut 120 Cap 121 Locking part

Claims

1. A hub unit bearing and a constant velocity joint, The hub unit bearing is an outer ring having a double row outer ring raceway on an inner circumferential surface; a hub having a double row inner ring raceway on an outer circumferential surface thereof and being rotationally driven by the constant velocity joint; a plurality of rolling elements are arranged for each row between the double row outer ring raceways and the double row inner ring raceways; a cap that is axially sandwiched between the hub and the constant velocity joint, the hub is configured to include a hub wheel and an inner ring fitted onto the hub wheel and having an inner ring raceway on an outer circumferential surface thereof, the inner ring raceway being an axially inner row of the double row inner ring raceways; The hub wheel has a crimping portion that presses an axially inner end face of the inner ring, The cap has a generally J-shaped cross section and is generally annular in shape, and includes a flat annular base plate portion arranged axially inside the crimped portion, a cylindrical cover portion extending axially outward from a radially outer end of the base plate portion and covering the crimped portion from the radially outer side, a locking portion extending radially inward from the axially outer end of the cylindrical cover portion, and a drain hole penetrating the cap. With the base plate portion sandwiched between the crimped portion and the constant velocity joint, a minimum diameter portion, which is a portion of the locking portion having the smallest inner diameter, is disposed axially outward of a maximum diameter portion, which is a portion of the crimped portion having the largest outer diameter, and has an inner diameter larger than the outer diameter of the maximum diameter portion, the central axis of the cap is eccentric with respect to the central axis of the hub, and only a circumferential portion of the locking portion overlaps with the crimped portion in the axial direction. Wheel drive unit.

2. the cap is configured in a comb-like shape including at least the locking portion and including a plurality of strips spaced apart from each other in a circumferential direction; The water drainage holes are provided in the portions between the strips adjacent to each other in the circumferential direction.

2. A wheel drive unit according to claim 1.

3. 3. The wheel drive unit according to claim 1, wherein at least a portion of the engaging portion including the minimum diameter portion is made of an elastic material.

4. 4. The wheel drive unit according to claim 1, wherein the drain hole is provided at a radially outer end of the cap.

5. 4. The wheel drive unit according to claim 1, wherein the drainage hole penetrates the base plate portion in the axial direction.

6. A method for assembling the wheel drive unit described in claim 1, comprising the steps of: a step of axially inserting the crimped portion into the inside of the cap in a state before the hub unit bearing and the constant velocity joint are assembled, positioning the entire locking portion axially outward of the maximum diameter portion of the crimped portion, and then eccentrically displacing a central axis of the cap and a central axis of the hub, so that a portion of the locking portion overlaps the crimped portion in the axial direction. How to assemble a wheel drive unit.

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