Hub unit bearing, wheel drive unit and assembly method thereof

Abstract

Prevents contamination of surrounding grease, such as production line equipment and other products. [Solution] A washer (20) held in the axial direction between a hub (6) and a constant velocity joint (3) has an annular flat plate (21) with its axially outer surface facing an axially inner end face of the hub (6) at an axial distance, an outer tubular portion (22) extending axially outward from the radially outer end of the annular flat plate (21) and disposed around the axially inner end face of the hub (6), and through holes (23) axially penetrating a plurality of locations in the circumferential direction of the annular flat plate (21). Grease (32) is applied to the axially outer surface of the annular flat plate (21) so as to close the axially outer openings of the through holes (23), and a portion of the grease is interposed between the axially inner end face of the hub (6) and the axially outer surface of the annular flat plate (21).

Description

[Technical Field]

[0001] The present disclosure relates to a hub unit bearing for rotatably supporting a wheel and a braking rotor relative to a suspension device, a wheel drive unit including the hub unit bearing, and an assembly method thereof. [Background technology]

[0002] Fig. 10 shows an example of a wheel drive unit 100 having a conventional structure, which is described in Japanese Patent Application Laid-Open No. 2009-214676. Note that, with respect to the wheel drive unit 100, the axially outer side is the left side in Fig. 10, 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 Fig. 10, which is the center side in the width direction of the vehicle when assembled to the vehicle.

[0003] The wheel drive unit 100 includes a hub unit bearing 101 and a constant velocity joint 102 .

[0004] The hub unit bearing 101 includes an outer ring 104, a hub 105, and a plurality of rolling elements 106a and 106b.

[0005] The outer ring 104 has double-row outer ring raceways 107a, 107b on its inner circumferential surface. The outer ring 104 is fixedly connected to the suspension device in use and does not rotate.

[0006] Hub 105 has double-row inner ring raceways 108a, 108b on its outer circumferential surface, and a rotating flange 109 that protrudes radially outward from a portion of the hub 105 located axially outward of outer ring 104. In use, hub 105 rotates integrally with the wheel and braking rotating member that are coupled and fixed to rotating flange 109.

[0007] Since the hub unit bearing 101 is for a drive wheel, the hub 105 has a spline hole 110 that penetrates in the axial direction at the radial center.

[0008] The hub 105 is formed by combining a hub ring 111 and an inner ring 112. The hub ring 111 has a rotation flange 109 on its axially outer side, an axially outer inner ring raceway 108a on its axially middle part of its outer peripheral surface, a spline hole 110 in its radial center, and a crimped part 113 bent radially outward at its axially inner end. The inner ring 112 has an axially inner inner ring raceway 108b on its outer peripheral surface, and is fitted onto the axially inner part of the hub ring 111, with its axially inner surface pressed down by the crimped part 113.

[0009] The rolling elements 106a, 106b are arranged between double-row outer ring raceways 107a, 107b and double-row inner ring raceways 108a, 108b, with a plurality of rolling elements in each row.

[0010] Constant velocity joint 102 is configured to include a joint outer ring 114 that is coupled to hub 105 so as to be able to transmit torque. Joint outer ring 114 has a cup-shaped mouth portion 119 that opens axially inward, and a shaft portion 115 that is fixed so as to protrude axially outward from the radial center of the axially outer surface of mouth portion 119. Shaft portion 115 has, at its axially intermediate portion, a male spline portion 116 that is spline-engaged with spline hole 110, and a male thread portion 117 at its axially outer end.

[0011] The joint outer ring 114 is coupled to the hub 105 so as to be able to transmit torque, by spline-engaging the male spline portion 116 with the spline hole 110, and by screwing the nut 103 onto the male threaded portion 117 and further tightening it.

[0012] When the automobile is in operation, the driving torque transmitted from a driving source such as an engine or an electric motor to the constant velocity joint 102 is transmitted to the hub 105 via the spline engagement between the male spline portion 116 and the spline hole 110.

[0013] At this time, a portion of the shaft portion 115 that is located axially more inward than the male spline portion 116 undergoes elastic torsional deformation. For this reason, if the axially inner surface of the crimped portion 113 and the axially outer surface of the joint outer ring 114 are brought into direct contact with each other, a stick-slip phenomenon may occur, in which the metal surfaces alternately slide and stick together in a short period of time. Because high surface pressure due to the tightening of the nut 103 acts on the contact area between the axially inner surface of the crimped portion 113 and the axially outer surface of the joint outer ring 114, if the stick-slip phenomenon occurs, an unpleasant noise known as a stick-slip sound may be generated.

[0014] Therefore, in the wheel drive unit 100 described in JP 2009-214676 A, a washer 118 is sandwiched between the axially inner surface of the crimped portion 113 and the axially outer surface of the joint outer ring 114. The washer 118 is made of a steel plate with sufficient strength because it is tightly sandwiched between the axially inner surface of the crimped portion 113 and the axially outer surface of the joint outer ring 114 by tightening the nut. In addition, the surface of the washer 118 (the surface of the steel plate that serves as the base material) is subjected to a diffusion plating of molybdenum disulfide to reduce the coefficient of friction with the mating surface that comes into contact with it.

[0015] Therefore, when a large driving torque is input to the constant velocity joint 102, before a large amount of energy accumulates between the crimped portion 113 and the joint outer ring 114, slippage in the circumferential direction can be caused at the contact portion between the axially inner surface of the crimped portion 113 and the axially outer surface of the washer 118 and / or at the contact portion between the axially outer surface of the joint outer ring 114 and the axially inner surface of the washer 118. Therefore, the generation of stick-slip noise between the crimped portion 113 and the joint outer ring 114 can be suppressed. [Prior art documents] [Patent documents]

[0016] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-214676 Summary of the Invention [Problem to be solved by the invention]

[0017] In the conventional structure described in JP 2009-214676 A, the molybdenum disulfide diffusion plating provided on the surface of the washer 118 is generally formed by shot peening. While the molybdenum disulfide diffusion plating formed in this manner can be formed to a sufficient depth (e.g., several tens of μm) on the surface of a soft metal with a low melting point, such as aluminum, it is difficult to form the plating to a sufficient depth on the surface of a steel plate, which is the base material of the washer 118. Therefore, when the wheel drive unit 100 is used and exposed to rainwater, muddy water, or the like, and circumferential slip occurs at the contact portion between the axially inner surface of the crimping portion 113 and the axially outer surface of the washer 118 and / or the contact portion between the axially outer surface of the joint outer ring 114 and the axially inner surface of the washer 118, it may be difficult to ensure sufficient durability of the molybdenum disulfide diffusion plating in terms of wear and rust. If the washer 118 is made of a soft metal such as an aluminum alloy, not only will it be prone to wear, but depending on the type of soft metal, galvanic corrosion may occur, making it impractical.

[0018] On the other hand, as another measure to suppress the generation of stick-slip noise between the crimped portion 113 and the joint outer ring 114, it is possible to adopt a structure in which the portion between the axially outer surface of the washer 118 and the axially inner surface of the crimped portion 113, and the portion between the axially inner surface of the washer 118 and the axially outer surface of the joint outer ring 114, are lubricated with grease containing a solid lubricant such as molybdenum disulfide that has a synergistic crystal structure and can reduce frictional resistance by sliding between layers.

[0019] When such a structure is adopted, it is conceivable that, after assembling outer ring 104, hub 105, and multiple rolling elements 106a, 106b on a manufacturing line for hub unit bearing 101, washer 118 may be attached to crimped portion 113, grease may be sandwiched between the axially inner surface of crimped portion 113 and the axially outer surface of washer 118, and grease may be applied to the axially inner surface of washer 118.

[0020] However, if this work is performed, there is a possibility that the grease applied to the axially inner surface of washer 118 will unintentionally adhere to production line equipment or other products, causing contamination of the surrounding area, during the period up to the time of joining hub unit bearing 101 and constant velocity joint 102. Because molybdenum disulfide particles are black and fine, there is a problem in that they are difficult to remove if they adhere to production line equipment or other products.

[0021] An object of the present disclosure is to provide a hub unit bearing that can prevent contamination by grease from surrounding areas such as production line equipment and other products, as well as a wheel drive unit including the hub unit bearing and an assembly method for the same. [Means for solving the problem]

[0022] A hub unit bearing according to one aspect of the present disclosure includes an outer ring, a hub, a plurality of rolling elements, a washer, and grease.

[0023] The outer ring has a plurality of outer ring raceways on its inner peripheral surface.

[0024] The hub has a plurality of rows of inner ring raceways on its outer circumferential surface and is rotationally driven by a constant velocity joint.

[0025] The plurality of rolling elements are disposed between the plurality of rows of outer ring raceways and the plurality of rows of inner ring raceways.

[0026] The washer is sandwiched in the axial direction between the hub and the constant velocity joint, and has an annular flat plate portion whose axially outer surface faces an axially inner end face of the hub at an axial distance, through holes that axially pass through the annular flat plate portion at multiple locations around its circumference, and an outer cylindrical portion that extends axially outward from a radially outer end of the annular flat plate portion and is disposed around the axially inner end of the hub.

[0027] The grease is applied to the axially outer surface of the annular flat plate portion so as to block the axially outer opening of the through hole, and a portion of the grease is interposed between the axially inner end face of the hub and the axially outer surface of the annular flat plate portion.

[0028] In one aspect of the hub unit bearing of the present disclosure, the hub can include a hub ring and an inner ring that has at least the axially innermost inner ring raceway of the multiple rows of inner ring raceways on its outer peripheral surface and is fitted onto the hub ring, and the hub ring can have a crimped portion that presses against the axially inner end face of the inner ring. In this case, the washer can have a locking portion that extends radially inward from the axially outer end of the outer tubular portion and is positioned axially outward of the portion of the crimped portion that has the largest outer diameter.

[0029] In the hub unit bearing according to one aspect of the present disclosure, the through hole may have, on the inner peripheral surface of the axially outer end thereof, an annular inclined surface portion whose outer diameter increases axially outward.

[0030] A wheel drive unit according to one aspect of the present disclosure includes a hub unit bearing, a constant velocity joint, and grease.

[0031] The hub unit bearing is an outer ring having a plurality of rows of outer ring raceways on its inner circumferential surface; a hub having a plurality of rows of inner ring raceways on its outer circumferential surface and being rotationally driven by a constant velocity joint; a plurality of rolling elements disposed between the plurality of rows of outer ring raceways and the plurality of rows of inner ring raceways, a washer that is axially sandwiched between the hub and the constant velocity joint; The washer has an annular flat portion whose axially outer surface faces the axially inner end face of the hub at an axial distance, through holes that penetrate the annular flat portion axially at multiple circumferential locations, and an outer cylindrical portion that extends axially outward from the radially outer end of the annular flat portion and is positioned around the axially inner end of the hub.

[0032] The constant velocity joint includes a joint outer ring having an axially outer surface facing an axially inner surface of the annular flat plate portion, and coupled to the hub so as to be able to transmit torque.

[0033] The grease is interposed between the axially inner end face of the hub and the axially outer surface of the annular flat plate portion, and between the axially outer surface of the joint outer ring and the axially inner surface of the annular flat plate portion, and is filled inside the through hole.

[0034] A method for assembling a wheel drive unit according to one aspect of the present disclosure is an assembly method for the wheel drive unit according to one aspect of the present disclosure, comprising the steps of: a first step of applying the grease to an axially outer surface of the annular flat plate portion so as to close an axially outer opening of the through hole; a second step of pressing an axially inner end surface of the hub against the grease applied to the axially outer surface of the annular flat plate portion, thereby adhering and supporting the washer to the axially inner end surface of the hub by the adhesive force of the grease; a third step of pressing the axially outer side surface of the joint outer ring against the axially inner side surface of the annular flat plate portion and squeezing the grease in the axial direction between the axially inner end face of the hub and the axially outer side surface of the annular flat plate portion, thereby discharging some of the grease through the through hole and from an axially inner opening of the through hole, and supplying it to a portion between the axially inner side surface of the annular flat plate portion and the axially outer side surface of the joint outer ring; Equipped with. [Effects of the Invention]

[0035] According to the hub unit bearing of one aspect of the present disclosure, contamination of surrounding equipment, such as production line equipment and other products, with grease can be prevented. [Brief explanation of the drawings]

[0036] [Figure 1] FIG. 1 is a half cross-sectional view showing a wheel drive unit according to a first embodiment of the present disclosure. [Figure 2] FIG. 2 is an enlarged view of part A in FIG. [Figure 3] FIG. 3 is a half cross-sectional view showing a hub unit bearing of the first example. [Figure 4] FIG. 4 is an enlarged view of part B in FIG. [Figure 5] FIG. 5 is a half cross-sectional view showing a wheel drive unit according to a second example of an embodiment of the present disclosure. [Figure 6] FIG. 6 is an enlarged view of part C in FIG. [Figure 7] FIG. 7 is a half cross-sectional view showing a hub unit bearing of the second example. [Figure 8] FIG. 8 is an enlarged view of part D in FIG. [Figure 9] FIG. 9(a) is a diagram of a third example of an embodiment of the present disclosure, corresponding to FIG. 2, and FIG. 9(b) is a diagram of the third example, corresponding to FIG. [Figure 10] FIG. 10 is a cross-sectional view showing an example of a wheel drive unit having a conventional structure. DETAILED DESCRIPTION OF THE INVENTION

[0037] [Example 1] A first example of an embodiment of the present disclosure will be described with reference to FIGS. 1 to 4. FIG.

[0038] (Structure of wheel drive unit 1) The wheel drive unit 1 includes a hub unit bearing 2 and a constant velocity joint 3. Note that with respect to the wheel drive unit 1, the axially outer side is the left side in Figs. 1 to 4, 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 Figs. 1 to 4, which is the center side in the width direction of the vehicle when assembled to the vehicle.

[0039] The hub unit bearing 2 includes an outer ring 5, a hub 6, a plurality of rolling elements 7a, 7b, and a washer 20.

[0040] The outer ring 5 has a plurality of outer ring raceways 8a, 8b on its inner peripheral surface. In this example, the outer ring 5 has double rows, i.e., two rows, of outer ring raceways 8a, 8b on its inner peripheral surface.

[0041] The outer ring 5 is made of a hard metal such as medium carbon steel.

[0042] In this example, the outer ring 5 has a stationary flange 9 that protrudes radially outward from an axially intermediate portion. The stationary flange 9 is a portion used to connect and fix the outer ring 5 to a knuckle of a suspension device. In use, the outer ring 5 is connected and fixed to the knuckle of the suspension device and does not rotate.

[0043] The hub 6 is disposed radially inside the outer ring 5 and coaxially with the outer ring 5. The hub 6 has multiple rows of inner ring raceways 10a, 10b on its outer peripheral surface. In this example, the hub 6 has double rows, i.e., two rows of inner ring raceways 10a, 10b, on its outer peripheral surface.

[0044] In this example, the hub 6 has a rotating flange 11 that protrudes radially outward from a portion located axially outward of the outer ring 5. The rotating flange 11 is a portion used to connect and fix a wheel and a rotating braking member to the hub 6. In use, the hub 6 rotates integrally with the wheel and rotating braking member that are connected and fixed to the rotating flange 11.

[0045] Since the hub unit bearing 2 is for a drive wheel, the hub 6 has a spline hole 12 that penetrates in the axial direction at the radial center.

[0046] The hub 6 includes an inner ring 13 and a hub ring 14 .

[0047] The inner ring 13 has, on its outer peripheral surface, at least the axially innermost inner ring raceway 10b of the multiple rows of inner ring raceways 10a, 10b. In this example, the inner ring 13 has, on its outer peripheral surface, the axially innermost inner ring raceway 10b of the double row of inner ring raceways 10a, 10b.

[0048] The inner ring 13 is made of a hard metal such as bearing steel and has a cylindrical shape.

[0049] Of the multiple rows of inner ring raceways 10a, 10b, the hub ring 14 has at least the axially outermost inner ring raceway 10a. In this example, the hub ring 14 has, on its outer peripheral surface, the axially outer inner ring raceway 10a of the double row of inner ring raceways 10a, 10b.

[0050] In this example, the hub ring 14 further has a rotating flange 11, a spline hole 12, a fitting shaft portion 15 onto which the inner ring 13 is fitted, and a crimping portion 16 that presses down on the axially inner surface 33 of the inner ring 13.

[0051] The fitting shaft portion 15 is provided at a portion located axially more inward than the axially outer inner ring raceway 10a, and has a cylindrical outer peripheral surface whose outer diameter does not change in the axial direction. A portion of the outer peripheral surface of the hub wheel 14 adjacent to the axially inner side of the axially outer inner ring raceway 10a is connected to the outer peripheral surface of the fitting shaft portion 15 by a stepped surface 17 facing axially inward.

[0052] The crimped portion 16 is bent radially outward from the axially inner end of the fitting shaft portion 15. An axially inner surface 18 of the crimped portion 16 is formed by a plane perpendicular to the axial direction of the hub 6. The crimped portion 16 has a maximum diameter portion P, where the outer diameter is the largest, at the axially middle portion of the outer peripheral surface. The outer peripheral surface of the crimped portion 16 has a shape in which the outer diameter decreases from the maximum diameter portion P toward both axial ends. In this example, the axially inner end surface of the hub 6 is formed by the axially inner surface 18 of the crimped portion 16, and the axially inner end portion of the hub 6 is formed by the crimped portion 16.

[0053] The hub ring 14 is made of a hard metal such as medium carbon steel.

[0054] The inner ring 13 is fitted onto the fitting shaft portion 15 of the hub ring 14, and is sandwiched from both axial sides between a stepped surface 17 and a crimped portion 16 of the hub ring 14. In this way, the hub 6 is formed by joining the inner ring 13 and the hub ring 14, and a preload is applied to the rolling elements 7a, 7b.

[0055] When implementing the present disclosure, the hub wheel may also have a shaft member and another inner ring having an inner ring raceway on the axially outer side. That is, a structure may be adopted in which the hub is configured by fitting two inner rings onto the shaft member. In this case, the inner ring is fitted axially inward of the portion of the shaft member onto which the other inner ring is fitted.

[0056] The rolling elements 7a, 7b are arranged between multiple rows of outer ring raceways 8a, 8b and multiple rows of inner ring raceways 10a, 10b, with multiple rolling elements 7a, 7b arranged in each row. This allows the hub 6 to be rotatably supported radially inside the outer ring 5. In this example, the rolling elements 7a, 7b are arranged between the double row of outer ring raceways 8a, 8b and the double row of inner ring raceways 10a, 10b, with multiple rolling elements 7a, 7b arranged in each row.

[0057] The rolling elements 7a, 7b are made of hard metal such as bearing steel or ceramics. The rolling elements 7a, 7b in each row are held by cages 19a, 19b and are arranged at equal intervals in the circumferential direction.

[0058] In this example, balls are used as the rolling elements 7a, 7b, but tapered rollers can also be used as the rolling elements. In this example, the pitch diameter of the rolling elements 7a in the axially outer row and the pitch diameter of the rolling elements 7b in the axially inner row are the same. However, the hub unit bearing and wheel drive unit of one embodiment of the present disclosure can also be applied to a structure in which the pitch diameter of the rolling elements in the axially outer row differs from the pitch diameter of the rolling elements in the axially inner row. Furthermore, the hub unit bearing and wheel drive unit of one embodiment of the present disclosure can also have three or more rows of rolling elements.

[0059] The washer 20 is sandwiched in the axial direction between the hub 6 and the constant velocity joint 3. Before being sandwiched in the axial direction between the hub 6 and the constant velocity joint 3, that is, before the hub unit bearing 2 and the constant velocity joint 3 are assembled, the washer 20 is adhered and supported to the axially inner end surface of the hub 6 by the adhesive force of the grease 32 applied to the axially outer surface of the annular flat plate portion 21.

[0060] The washer 20 has an annular flat plate portion 21 , a plurality of through holes 23 , and an outer cylindrical portion 22 .

[0061] The annular flat plate portion 21 is sandwiched between the hub 6 and the constant velocity joint 3. The annular flat plate portion 21 may have any shape as long as it is sandwiched between the hub 6 and the constant velocity joint 3 and is configured in an annular shape so as to prevent interference with the shaft portion 26 engaged with the spline hole 12. In this example, the annular flat plate portion 21 has a hollow circular shape when viewed in the axial direction.

[0062] The multiple through holes 23 are provided so as to penetrate the annular flat plate portion 21 in the axial direction at multiple locations in the circumferential direction. The shape, number, and circumferential arrangement of the through holes 23 can be determined arbitrarily. That is, the through holes 23 can have any opening shape, such as a circle, an ellipse, or a polygon, when viewed in the axial direction. The through holes 23 can also be configured as elongated holes extending in the circumferential direction and / or the radial direction. In this example, the through holes 23 have a circular opening shape when viewed in the axial direction.

[0063] The number of through holes 23 can be about 2 to 15. In this example, the number of through holes 23 is 8. The through holes 23 can be arranged at equal intervals in the circumferential direction, or can be arranged at unequal intervals in the circumferential direction. In this example, the through holes 23 are arranged at equal intervals in the circumferential direction.

[0064] In this example, each of the through holes 23 has, on the inner peripheral surface at the axially outer end thereof, an annular inclined surface portion 24 whose outer diameter increases toward the axially outer side. In this example, the annular inclined surface portion 24 is formed by a truncated cone surface.

[0065] The outer cylindrical portion 22 extends axially outward from the radially outer end of the annular flat plate portion 21, and is disposed around the axially inner end (in this example, the crimped portion 16) of the hub 6. The presence of the outer cylindrical portion 22 improves bending rigidity and prevents the grease 32 applied to the axially outer surface 30 of the annular flat plate portion 21 of the washer 20 from adhering to production line equipment, other products, etc., and contaminating the surrounding area.

[0066] The outer cylindrical portion 22 can have any shape as long as it is configured cylindrically so as to be disposed around the axially inner end of the hub 6. In this example, the outer cylindrical portion 22 has a cylindrical shape whose inner and outer diameters do not change in the axial direction. In this example, the outer cylindrical portion 22 has an inner diameter slightly larger than the outer diameter of the maximum diameter portion P of the crimped portion 16, and is disposed around the crimped portion 16 without significant radial play. This positions the washer 20 radially relative to the hub 6. The axially outer end of the outer cylindrical portion 22 closely faces the axially inner surface 33 of the inner ring 13.

[0067] The washer 20 can be made of a metal plate having sufficient strength, such as a steel plate. Specifically, the washer 20 is made by subjecting a metal plate to punching and bending using a press.

[0068] The constant velocity joint 3 has an axially outer surface 27 facing the axially inner surface of the annular flat plate portion 21, and is configured to include a joint outer ring 25 coupled to the hub 6 so as to be able to transmit torque.

[0069] The joint outer ring 25 has a cup-shaped mouth portion 35 that opens axially inward, and is made of a hard metal such as medium carbon steel.

[0070] In this example, the joint outer ring 25 further includes a shaft portion 26 fixedly provided so as to protrude axially outward from the bottom of the mouth portion 35. The shaft portion 26 has a male spline portion 28 in the axial middle portion and a male thread portion 29 at the axially outer end portion. The joint outer ring 25 is coupled to the hub 6 so as to be able to transmit torque by spline-engaging the male spline portion 28 with the spline hole 12 and threading the nut 4 onto the male thread portion 29 and further tightening it.

[0071] The constant velocity joint 3 is constructed by supporting a joint inner ring via a plurality of balls inside the mouth portion 35 of the joint outer ring 25 so that the joint inner ring can swing and transmit torque. A drive shaft that is driven and rotated by a drive source such as an engine or an electric motor is fixedly connected to the joint inner ring. When the vehicle is in operation, the drive torque input from the drive shaft to the joint inner ring is transmitted to the joint outer ring 25 via the balls, and further transmitted to the hub 6 via the spline engagement between the male spline portion 28 and the spline hole 12.

[0072] The wheel drive unit 1 further includes grease 32. As shown in FIG. 2 , the grease 32 is present in the area between the axially inner end face of the hub 6 (in this example, the axially inner surface 18 of the crimped portion 16) and the axially outer surface 30 of the annular flat plate portion 21, and in the area between the axially outer surface 27 of the joint outer ring 25 and the axially inner surface 31 of the annular flat plate portion 21, and is also filled inside the through hole 23. Specifically, in this example, a portion of the grease 32 is present between a radially intermediate portion of the axially inner surface 18 of the crimped portion 16 and a radially intermediate portion of the axially outer surface 30 of the annular flat plate portion 21 that includes an axially outer opening of the through hole 23, and another portion of the grease 32 is present between a radially intermediate portion of the axially outer surface 27 of the joint outer ring 25 and a radially intermediate portion of the axially inner surface 31 of the annular flat plate portion 21 that includes an axially inner opening of the through hole 23.

[0073] 2 to 4, the grease 32 is shown with a matte finish. In addition, in Fig. 2, the axial thickness of the grease 32 present between the axially inner surface 18 of the crimping portion 16 and the axially outer surface 30 of the annular flat plate portion 21, and between the axially outer surface 27 of the joint outer ring 25 and the axially inner surface 31 of the annular flat plate portion 21 is shown exaggerated.

[0074] The grease 32 may be made of grease containing a solid lubricant, such as, but not limited to, molybdenum disulfide, organic molybdenum, or tungsten disulfide.

[0075] As described above, in the wheel drive unit 1 of this example, the area between the axially inner surface 18 of the crimped portion 16 and the axially outer surface 30 of the annular flat plate portion 21, and the area between the axially outer surface 27 of the joint outer ring 25 and the axially inner surface 31 of the annular flat plate portion 21 are lubricated with grease 32. Therefore, when a portion of the shaft portion 26 located axially more inward than the male spline portion 28 elastically torsionally deforms as driving torque is input from the drive source to the constant velocity joint 3, the lubricating action of the grease 32 can cause circumferential slippage in the area between the axially inner surface 18 of the crimped portion 16 and the axially outer surface 30 of the annular flat plate portion 21 and / or the area between the axially outer surface 27 of the joint outer ring 25 and the axially inner surface 31 of the annular flat plate portion 21. This makes it possible to suppress stick-slip noise from occurring between the crimped portion 16 and the joint outer ring 25.

[0076] Furthermore, in the wheel drive unit 1 of this example, there are through holes 23 that axially penetrate the annular flat plate portion 21 at multiple locations in the circumferential direction, and each through hole 23 is filled with grease 32. Therefore, each through hole 23 functions as a retaining portion for the grease 32, and it is possible to maintain a good lubricated state for a long period of time in the portion between the axially inner surface 18 of the crimping portion 16 and the axially outer surface 30 of the annular flat plate portion 21, and in the portion between the axially outer surface 27 of the joint outer ring 25 and the axially inner surface 31 of the annular flat plate portion 21.

[0077] (Assembly method of wheel drive unit 1) Next, a description will be given of a method for assembling the wheel drive unit 1 of this embodiment. The method for assembling the wheel drive unit 1 of this embodiment includes a first step, a second step, and a third step.

[0078] In the first step, grease 32 is applied to the axially outer surface 30 of the annular flat plate portion 21 of the washer 20 so as to close the axially outer opening of the through hole 23. Specifically, in the first step, grease 32 is applied to the axially outer surface 30 of the annular flat plate portion 21 so as to close the axially outer opening of the through hole 23 and not overflow from the axially inner side of the through hole 23.

[0079] The grease 32 can be applied in a ring shape to the radially middle portion of the axially outer surface 30 of the annular flat portion 21, which includes the axially outer opening of the through hole 23, or can be applied to multiple circumferential locations on the axially outer surface 30 of the annular flat portion 21, which include the axially outer opening of the through hole 23.

[0080] Next, in the second step, the axially inner end face of the hub 6 is pressed against the grease 32 applied to the axially outer surface of the annular flat portion 21, and the adhesive force of the grease 32 adheres and supports the washer 20 to the axially inner end face of the hub 6.

[0081] Specifically, prior to the second step, all of the components constituting the hub unit bearing 2, except for the washer 20, are assembled. This assembly process can be performed, for example, as follows: First, the rolling elements 7a, 7b of each row are placed radially inside the double-row outer ring raceways 8a, 8b of the outer ring 5, while being held by cages 19a, 19b. Next, the hub ring 14 is inserted radially inside the outer ring 5 from the outside in the axial direction. Next, the inner ring 13 is press-fit onto the mating shaft portion 15 of the hub ring 14 from the inside in the axial direction. Next, the axially inner end of the hub ring 14 is plastically deformed radially outward to form a crimped portion 16, and the inner ring 13 and hub ring 14 are joined to form the hub 6. Note that the order of these assembly steps can be reversed or performed simultaneously as appropriate, as long as no contradictions arise.

[0082] 3 and 4 , in the second step, the outer cylindrical portion 22 is disposed around the axially inner end portion of the hub 6 (in this example, the crimped portion 16), and the axially inner surface 18 of the crimped portion 16 is pressed against the grease 32 applied to the axially outer surface 30 of the annular flat portion 21. More specifically, the axially inner surface 18 of the crimped portion 16 is pressed against the grease 32 applied to the axially outer surface 30 of the annular flat portion 21 to an extent that the grease 32 does not overflow from the axially inner opening of the through hole 23. As a result, the adhesive force of the grease 32 adheres and supports the washer 20 to the axially inner end portion of the hub 6.

[0083] 3 and 4 show the hub unit bearing 2 in a state where the second step has been completed, which corresponds to the hub unit bearing of one embodiment of the present disclosure.

[0084] When the second step is completed, the grease 32 is applied to the axially outer surface of the annular flat plate portion 21 so as to block the axially outer opening of the through hole 23, and a portion of the grease 32 is interposed between the axially inner end face of the hub 6 and the axially outer surface of the annular flat plate portion 21. In other words, at least a portion of the grease 32 is interposed between the axially inner end face of the hub 6 and a portion of the axially outer surface of the annular flat plate portion 21 that includes the axially outer opening of the through hole 23. The remaining portion of the grease 32 can be disposed inside the through hole 23.

[0085] When the second step is completed, the axial thickness of the grease 32 sandwiched between the axial outer surface 30 of the annular flat portion 21 and the axial inner surface 18 of the crimping portion 16 is greater than the axial thickness of the grease 32 interposed in the space when the assembly of the wheel drive unit 1 is completed.

[0086] In this example, when the second step is completed, the grease 32 is filled only in the axially outer portion of the inside of the through hole 23, more specifically, in the portion where the annular inclined surface portion 24 is formed. In other words, the grease 32 is not filled in the axially inner portion of the inside of the through hole 23.

[0087] In the third step, the axially outer surface 27 of the joint outer ring 25 is pressed against the axially inner surface 31 of the annular flat plate portion 21, and the grease 32 is crushed in the axial direction between the axially inner end face of the hub 6 (in this example, the axially inner surface 18 of the crimping portion 16) and the axially outer surface 30 of the annular flat plate portion 21, causing a portion of the grease 32 to be ejected through the through hole 23 from the axially inner opening of the through hole 23 and supplied to the portion between the axially inner surface 31 of the annular flat plate portion 21 and the axially outer surface 27 of the joint outer ring 25.

[0088] In this example, the shaft portion 26 is inserted into the spline hole 12 from the axially inner side, the axially outer surface 27 of the joint outer ring 25 is pressed against the axially inner surface 31 of the annular flat plate portion 21, and the grease 32 is crushed in the axial direction between the axially inner surface 18 of the crimped portion 16 and the axially outer surface 30 of the annular flat plate portion 21. Some of the grease 32 crushed in the axial direction moves axially inward within the through hole 23 and is discharged from the axially inner opening of the through hole 23 to be supplied to the portion between the axially inner surface 31 of the annular flat plate portion 21 and the axially outer surface 27 of the joint outer ring 25.

[0089] In the third step, the work of squeezing the grease 32 in the axial direction between the axially inner end face of the hub 6 and the axially outer surface 30 of the annular flat plate portion 21 can be performed before threading the nut 4 onto the male thread portion 29, or can be performed by using the axial force generated by threading the nut 4 onto the male thread portion 29 and further tightening it. If this work is performed before threading the nut 4 onto the male thread portion 29, the assembly of the wheel drive unit 1 is completed by threading the nut 4 onto the male thread portion 29 and further tightening it after the third step is completed. On the other hand, if this work is performed by using the axial force generated by threading the nut 4 onto the male thread portion 29 and further tightening it, the assembly of the wheel drive unit 1 is completed simultaneously with the completion of the third step.

[0090] In any case, in this example, the through hole 23 has, on its inner peripheral surface at the axially outer end, an annular inclined surface portion 24 whose outer diameter increases axially outward. Therefore, when the grease 32 sandwiched between the axially outer surface 30 of the annular flat portion 21 and the axially inner surface 18 of the crimping portion 16 is compressed in the axial direction, part of the grease 32 is guided by the annular inclined surface portion 24 and easily enters the inside of the through hole 23. Therefore, it is easy to ensure the amount of grease 32 that is discharged from the axially inner opening of the through hole 23 and supplied to the portion between the axially inner surface 31 of the annular flat portion 21 and the axially outer surface 27 of the joint outer ring 25.

[0091] As described above, in the assembly method for wheel drive unit 1 of this example, when the second step is completed, grease 32 has not been applied to the axially inner surface 31 of the annular flat plate portion 21 or the outer peripheral surface of the outer cylindrical portion 22. Therefore, it is possible to effectively prevent grease 32 from unintentionally adhering to the surrounding area (production line equipment, other products, etc.) and contaminating the surrounding area until the hub unit bearing 2 and constant velocity joint 3 are joined in the third step and subsequent operations.

[0092] Furthermore, in this example, when the second step is completed, the grease 32 is not filled in the axially inner portions of the through holes 23. Therefore, even if the gap between the axially outer surface 30 of the annular flat portion 21 and the axially inner surface 18 of the crimping portion 16 narrows slightly due to the washer 20 hitting a surrounding object or the like during the subsequent steps until the hub unit bearing 2 and the constant velocity joint 3 are joined, it is possible to effectively prevent some of the grease 32 from being discharged through each of the through holes 23 and from the axially inner openings of the through holes 23. In other words, it is possible to effectively prevent the surrounding area from being contaminated by the grease 32.

[0093] The second and third steps can be performed on the same production line, or on different production lines. When the second and third steps are performed on different production lines, for example, the second step can be performed on a production line for the hub unit bearing 2, and the third step can be performed on a production line for the vehicle. In this case, the hub unit bearing 2 shown in FIGS. 3 and 4 is shipped from the production line for the hub unit bearing 2 and delivered to the production line for the vehicle. Then, even during this transportation from shipment to delivery, it is possible to effectively prevent the surrounding area from being contaminated by the grease 32.

[0094] [Example 2] A second example of the embodiment of the present disclosure will be described with reference to FIGS.

[0095] In the wheel drive unit 1a of this example, the hub ring 14a that constitutes the hub 6a of the hub unit bearing 2a does not have a crimped portion at its axially inner end. In this example, the hub 6a is constructed by press-fitting the inner ring 13 onto the mating shaft portion 15 of the hub ring 14a, and then abutting the axially outer end face of the inner ring 13 against a stepped surface 17 of the hub ring 14a, thereby connecting and fixing the inner ring 13 and the hub ring 14a. In this state, the axially inner surface 33 of the inner ring 13 protrudes axially inward beyond the axially inner end face of the hub ring 14a.

[0096] In this example, the axially inner end face of the hub 6a is formed by the axially inner surface 33 of the inner ring 13, and the axially inner end portion of the hub 6a is formed by the axially inner end portion of the inner ring 13. That is, in the wheel drive unit 1a of this example, the annular flat plate portion 21a of the washer 20a is sandwiched between the axially inner surface 33 of the inner ring 13 and the axially outer surface 27 of the joint outer ring 25. Also, in this example, the outer tubular portion 22a of the washer 20a is disposed around the axially inner end portion of the inner ring 13.

[0097] In the wheel drive unit 1a of this example, as shown in Figure 6, the grease 32 is interposed in the area between the axial inner surface 33 of the inner ring 13 and the axial outer surface 30 of the annular flat plate portion 21a, and in the area between the axial outer surface 27 of the joint outer ring 25 and the axial inner surface 31 of the annular flat plate portion 21a, to lubricate these areas and also fill the inside of each through hole 23.

[0098] In the wheel drive unit 1a of this example, when a portion of the shaft portion 26 located axially more inward than the male spline portion 28 elastically torsionally deforms in response to input of drive torque from the drive source to the constant velocity joint 3, the lubricating action of the grease 32 can cause circumferential slippage in the portion between the axially inner surface 33 of the inner ring 13 and the axially outer surface 30 of the annular flat plate portion 21a and / or the portion between the axially outer surface 27 of the joint outer ring 25 and the axially inner surface 31 of the annular flat plate portion 21a. Therefore, the generation of stick-slip noise between the inner ring 13 and the joint outer ring 25 can be suppressed.

[0099] The other configurations and effects of the second example are the same as those of the first example.

[0100] [Example 3] A third example of the embodiment of the present disclosure will be described with reference to Fig. 9(a) and Fig. 9(b). Fig. 9(a) is a diagram of this example that corresponds to Fig. 2, and Fig. 9(b) is a diagram of this example that corresponds to Fig. 4.

[0101] In this example, the washer 20b has a locking portion 34 that extends radially inward from the axially outer end of the outer tubular portion 22. The locking portion 34 is disposed axially outward of the maximum diameter portion P of the crimping portion 16. In this example, the locking portion 34 has an inner diameter that is slightly smaller than the outer diameter of the maximum diameter portion P.

[0102] In this example, locking portion 34 engages with the radially outer end of crimped portion 16 from the axially outer side over the entire circumference, preventing washer 20b from falling off axially inward from crimped portion 16. This makes it easy to join the hub unit bearing and constant velocity joint.

[0103] In this example, in the second step of the assembly method for the wheel drive unit, the task of positioning the locking portion 34 axially outward of the maximum diameter portion P of the crimped portion 16 can be performed, for example, by pushing the locking portion 34 against the outer peripheral surface of the crimped portion 16 from the axially inner side, thereby elastically expanding the diameter of the locking portion 34 and passing it axially through the maximum diameter portion P of the crimped portion 16.

[0104] When implementing the hub unit bearing and wheel drive unit according to one embodiment of the present disclosure, the inner diameter of locking portion 34 can be the same as or larger than the outer diameter of maximum diameter portion P. In this case, locking portion 34 engages with the radially outer end of crimped portion 16 from the axially outer side at a portion in the circumferential direction, thereby preventing washer 20b from falling off axially inward relative to crimped portion 16. Furthermore, this facilitates the work of positioning locking portion 34 axially outward of maximum diameter portion P of crimped portion 16 in the second step of the method for assembling the wheel drive unit.

[0105] The other configurations and effects of the third example are the same as those of the first example. [Explanation of symbols]

[0106] 1, 1a Wheel drive unit 2, 2a Hub unit bearing 3 Constant velocity joint 4 nuts 5 outer ring 6, 6a hub 7a, 7b rolling elements 8a, 8b outer raceway 9 Stationary Flange 10a, 10b Inner raceway 11 Rotating flange 12 spline holes 13 Inner Circle 14, 14a hub wheel 15 Mating shaft 16 Crimping part 17 Step surface 18 Axial inner surface 19a, 19b retainer 20, 20a, 20b Washers 21, 21a Annular flat plate portion 22, 22a Outer cylinder part 23 Through hole 24 Annular inclined surface section 25 Outer ring for joint 26 Shaft 27 Axial outer surface 28 Male spline part 29 Male thread 30 Axial outer surface 31 Axial inner surface 32 Grease 33 Axial inner surface 34 Locking part 35 Mouse section 100 Wheel drive unit 101 Hub unit bearing 102 Constant velocity joint 103 Nut 104 outer ring 105 Hub 106a, 106b rolling elements 107a, 107b outer raceway 108a, 108b inner raceway 109 Rotating flange 110 spline hole 111 Hub Wheel 112 Inner circle 113 Crimping part 114 Outer ring for joint 115 Shaft 116 Male spline part 117 Male thread 118 Washer 119 Mouse section

Claims

1. an outer ring having a plurality of rows of outer ring raceways on its inner circumferential surface; a hub having a plurality of rows of inner ring raceways on its outer circumferential surface and being rotationally driven by a constant velocity joint; a plurality of rolling elements disposed between the plurality of rows of outer ring raceways and the plurality of rows of inner ring raceways; a washer that is axially sandwiched between the hub and the constant velocity joint; grease; The washer has an annular flat plate portion whose axially outer surface faces an axially inner end face of the hub at an axial distance, through holes penetrating the annular flat plate portion in the axial direction at a plurality of circumferential locations, and an outer cylindrical portion extending axially outward from a radially outer end of the annular flat plate portion and disposed around an axially inner end of the hub, The grease is applied to the axially outer surface of the annular flat plate portion so as to close the axially outer opening of the through hole, and a part of the grease is interposed between the axially inner end face of the hub and the axially outer surface of the annular flat plate portion. Hub unit bearing.

2. the hub is configured to include a hub wheel and an inner ring having, on its outer peripheral surface, at least the axially innermost inner ring raceway among the plurality of rows of inner ring raceways, and fitted onto the hub wheel; the hub ring has a crimping portion that presses against an axially inner end face of the inner ring, 2. The hub unit bearing according to claim 1, wherein the washer has a locking portion that extends radially inward from an axially outer end of the outer cylindrical portion and is positioned axially outward of a portion of the crimped portion that has a largest outer diameter.

3. 2. The hub unit bearing according to claim 1, wherein the through hole has, on an inner peripheral surface at an axially outer end thereof, an annular inclined surface portion whose outer diameter increases as it extends axially outward.

4. The hub unit includes a bearing, a constant velocity joint, and grease. The hub unit bearing is an outer ring having a plurality of rows of outer ring raceways on its inner circumferential surface; a hub having a plurality of rows of inner ring raceways on its outer circumferential surface and being rotationally driven by a constant velocity joint; a plurality of rolling elements disposed between the plurality of rows of outer ring raceways and the plurality of rows of inner ring raceways, a washer that is axially sandwiched between the hub and the constant velocity joint; The washer has an annular flat plate portion whose axially outer surface faces an axially inner end face of the hub at an axial distance, through holes penetrating the annular flat plate portion in the axial direction at a plurality of circumferential locations, and an outer cylindrical portion extending axially outward from a radially outer end of the annular flat plate portion and disposed around an axially inner end of the hub, the constant velocity joint includes a joint outer ring having an axially outer surface facing an axially inner surface of the annular flat plate portion, the joint outer ring being coupled to the hub so as to be able to transmit torque, the grease is present in a portion between an axially inner end face of the hub and an axially outer surface of the annular flat plate portion, and in a portion between an axially outer surface of the joint outer ring and an axially inner surface of the annular flat plate portion, and is filled inside the through hole. Wheel drive unit.

5. 5. A method for assembling the wheel drive unit according to claim 4, comprising the steps of: a first step of applying the grease to an axially outer surface of the annular flat plate portion so as to close an axially outer opening of the through hole; a second step of pressing an axially inner end surface of the hub against the grease applied to the axially outer surface of the annular flat plate portion, thereby adhering and supporting the washer to the axially inner end surface of the hub by the adhesive force of the grease; a third step of pressing the axially outer side surface of the joint outer ring against the axially inner side surface of the annular flat plate portion and squeezing the grease in the axial direction between the axially inner end face of the hub and the axially outer side surface of the annular flat plate portion, thereby discharging a portion of the grease through the through hole and from an axially inner opening of the through hole, and supplying the grease to a portion between the axially inner side surface of the annular flat plate portion and the axially outer side surface of the joint outer ring; A method for assembling a wheel drive unit, comprising:

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