drive wheel bearing device

Abstract

Drive wheel bearing device with a double-row ball bearing (2) and a constant velocity joint (3) which are detachably integrated, wherein in this device the double-row ball bearing (2) comprises the following: an outer element (7) comprising a body mounting flange (7b) to be mounted on a vehicle body, wherein the body mounting flange (7b) is integrally formed on the outer circumference and is provided with an integrally formed double-row outer running surface (7a) on the inner circumference; an inner element (8) formed from a wheel hub (1) and a cylindrical inner ring element, wherein the wheel hub (1) has a wheel mounting flange (4) for mounting a wheel, the wheel mounting flange (4) being integral at one end and having on its outer circumference an inner running surface (1a) arranged opposite the double-row outer running surface (7a), and a cylindrical section (1b) extending axially from the inner running surface (1a), wherein the inner ring element is pressed onto the wheel hub (1) and has on its outer circumference the other inner running surface (5a) arranged opposite the double-row outer running surface (7a); and a double-row roller element (9) which is mounted so as to roll freely between the running surfaces (1a, 5a, 7a) of the inner element (8) and the outer element (7); and the constant velocity joint (3) has an outer joint element (14) with a cup-shaped outlet section (18), a shoulder section (19) forming the base of the outlet section (18), and a cylindrical shaft section (20) extending axially from the shoulder section (19), wherein the shaft section (20) is provided with an internal thread (20a), and wherein the outlet section (18), the shoulder section (19) and the shaft section (20) are integrally formed in the outer joint element (14), wherein end faces (13a, 19a) are formed on the respective end faces of the shoulder section (19) of the outer joint element (14) and the inner ring element, and wherein the face teeth (13a, 19a) are supported by pressure through a fastening screw (21) which rests against an outer end face of the wheel hub (1) and is screwed into the internal thread (20a) of the shaft section (20), and wherein the double-row ball bearing (2) and the constant velocity joint (3) are coupled to each other in such a way that the double-row ball bearing (2) and the constant velocity joint (3) can transmit torque and are axially separable, wherein the wheel hub (1) and the inner ring element are plastically integrally coupled, and wherein on the surfaces of the face teeth (13a, 19a) as a result of a Surface modification creates a residual compressive stress, wherein an outer seal (68) is mounted on the outer diameter of the shoulder section (19) of the outer joint element (14), the outer seal (68) includes a cylindrical metal core (69) pressed onto the outer diameter of the shoulder section (19), and a sealing element (70) vulcanized to the metal core (69) or integrally bonded to it by means of a similar bonding process, and a lip (70a, 70b) of the sealing element (70) is brought into elastic contact with the inner element (8) or an inner seal (12) of the seal, thereby sealing the engagement section of the face teeth (13a, 19a), and wherein the inner seal (12) is designed as a packing seal, which is provided with an annular sealing plate (73) and a wiper ring (74) having a substantially L-shaped cross-section, the sealing plate (73) being formed from a metal core (71) fitted into the end of the outer element (7), the metal core (71) having a substantially L-shaped cross-section, and a sealing element (72) vulcanized to the metal core (71), the wiper ring (74) being formed from a cylindrical part (74a) pressed onto the outer diameter of the inner ring (5) and an upright section (74b) extending radially outward from the cylindrical part (74a), the sealing element (70) of the outer seal (68) having a lateral lip (70a) extending laterally radially outward and a radial lip (70b) extending laterally radially inward,the lateral lip (70a) is brought into elastic contact with a side surface of the upright section (74b) of the wiper ring (74), and the radial lip (70b) is brought into elastic contact with the outer diameter of the inner ring (5).

Description

TECHNICAL FIELD

[0001] The present invention relates to a drive wheel bearing device that rotatably supports a drive wheel of a vehicle such as an automobile, and more particularly to a drive wheel bearing device having a bearing unit and a constant velocity joint that are detachably integrated. STATE OF THE ART

[0002] Since a power transmission device that transmits the engine power of a vehicle such as an automobile to a wheel needs to transmit the power from the engine to the wheel and handle radial or axial displacements and a moment displacement from the wheel (caused by jumps or turns while driving on an uneven road), one end of a drive shaft disposed between the engine side and the drive wheel side is connected to a differential via a sliding type constant velocity joint, and the other end is connected to a wheel via a drive wheel bearing device including a fixed type constant velocity joint.

[0003] In recent years, the desire for greater fuel efficiency has grown significantly in response to the need for resource conservation and environmental concerns. Of all the components that make up an automobile, wheel bearings, and more specifically, reducing their weight, have long been the focus of attention, as such weight reduction is a key factor in meeting the desire for greater fuel efficiency. Various proposals for lightweight wheel bearings have already been put forward. Equally important is the reduction of costs by simplifying assembly and disassembly work at an automobile production site or similar facility, or in a maintenance workshop.

[0004] One in Fig. The drive wheel bearing device shown in Figure 29 is a typical example that meets this requirement. This drive wheel bearing device has a structure in which a double-row ball bearing 101 and a constant velocity joint 102 are detachably integrated. The double-row ball bearing 101 includes: an outer member 103 having a body mounting flange 103b to be mounted on a vehicle body, the body mounting flange 103b being integrally formed and having double-row outer raceways 103a and 103a formed on its inner periphery;an inner member 106 formed from a wheel hub 104 and an inner ring 105, the wheel hub 104 having a wheel mounting flange 104b for mounting a wheel (not shown), the wheel mounting flange 104b being integrally formed at one end and having on its outer periphery an inner raceway surface 104a disposed opposite one of the double-row outer raceways 103a and 103a, and a cylindrical portion 104c extending axially from the inner raceway surface 104a; an inner ring 105 press-fitted onto the cylindrical portion 104c of the wheel hub 104 and having on its outer periphery an inner raceway surface 105a, the inner raceway surface 105a disposed opposite the other of the double-row outer raceways 103a and 103a;and double-row balls 108 and 108, which are housed between the raceways via a cage 107 disposed therebetween, allowing free rolling. Furthermore, the inner ring 105 is axially fixed to the wheel hub 104 by means of a swaged portion 109 formed by plastically deforming the end of the cylindrical portion 104c. Furthermore, a spur gear 109a is formed on the end surface of the swaged portion 109. Here, the spur gear 109a of the swaged portion 109 is formed during the swaging process.

[0005] Furthermore, seals 110 and 111 are mounted at the opening of an annular space formed between the outer member 103 and the inner member 106. This prevents the leakage of grease contained in the bearing and the penetration of rainwater, dust, etc. into the bearing from the outside.

[0006] The constant velocity joint 102 includes an outer joint member 112, a joint inner ring 113, a cage 114, and a torque transmitting ball 115. The outer joint member 112 has a cup-shaped mouth portion 116, a shoulder portion 117 forming the bottom of the mouth portion 116, and a hollow shaft portion 118 extending axially from the shoulder portion 117. The mouth portion 116, the shoulder portion 117, and the shaft portion 118 are integrally formed in the outer joint member. An internal thread 118a is formed on the inner periphery of the shaft portion 118. Furthermore, a spur gear 117a is formed on the end surface of the shoulder portion 117.The spur gear 117a engages with the spur gear 109a formed on the end surface of the swaged portion 109, and torque from a drive shaft (not shown) is transmitted to the wheel mounting flange 104b via the constant velocity joint 102 and the inner member 106.

[0007] Here, a fixing screw 119 is screwed into the internal thread 118a of the shaft portion 118, and the end gears 117a and 109a of the outer joint member 112 and the inner member 106 (with the end gears 117a and 109a disposed opposite each other) are supported by pressure by the fixing screw 119, thereby detachably integrating the double-row ball bearing 101 and the constant velocity joint 102. This makes it possible to realize a reduction in weight and size and simplify the disassembly and assembly processes (see, for example, Patent Document 1).

[0008] Patent Document 1: JP-A-63-184501

[0009] Also known from the prior art is document JP 2003-118309 A, which describes a wheel bearing device for a drive axle. Document DE 10 2006 032 159 A1 describes a bearing assembly for a motor vehicle wheel hub that can be driven via a pivot joint. Document JP 2008-018821 A also describes a wheel bearing device for a drive wheel. Document DE 100 47 125 A1 relates to a wheel bearing assembly for use in a motor vehicle. DISCLOSURE OF THE INVENTION PROBLEM TO BE SOLVED BY THE PRESENT INVENTION

[0010] Such a drive wheel bearing device improves processability because the spur gear 109a is formed while the upset portion 109 is being formed at the time of oscillation upsetting, and can reduce costs by reducing the number of processing steps. Another feature of this drive wheel bearing device is that, since the torque is transmitted through the spur gears 109a and 117a, it is possible to realize a reduction in weight and size and simplify the disassembly and assembly processes. However, since the spur gear 109a is formed while the upset portion 109 is being formed at the time of oscillation upsetting, its tooth surface retains the surface hardness obtained after cold plastic deformation, and the surface hardness exhibits only a slight increase compared to the surface hardness obtained after forging the wheel hub 104.Since the fatigue strength generally increases proportionally to the surface hardness, a significant increase in the fatigue strength of the spur gear 109a cannot be expected.

[0011] Here, high-frequency induction quenching can be performed on the face gears 109a and 117a to increase the surface hardness, thereby improving wear resistance and fatigue strength. However, this is undesirable because it not only deteriorates the meshing between the face gears 109a and 117a due to warpage resulting from heat treatment, but also causes a reduction in impact toughness due to a high degree of hardness.

[0012] The present invention is based on these observations, and an object of the present invention is to provide a drive wheel bearing device which improves the workability at the time of disassembly and assembly and increases the durability.

[0013] Another object of the present invention is to increase durability by guaranteeing the amount by which an inner ring is compressed and by reducing the deformation of the inner ring due to oscillatory upsetting.

[0014] Another object of the present invention is to increase the sealing performance of an engagement portion of spur gears. MEANS TO SOLVE THE PROBLEM

[0015] To achieve the above-mentioned objects, the present invention relates to a drive wheel bearing device as defined in claim 1.

[0016] As described above, in the drive wheel bearing device, since the inner ring is fixed to the wheel hub by means of the swaged portion formed by plastically deforming one end of the cylindrical portion of the wheel hub radially outward, the spur gears are formed on the respective end surfaces of the shoulder portion of the outer joint member and the swaged portion, the spur gears are supported by pressure by the fastening screw which abuts an outer end surface of the wheel hub and is screwed to the internal thread of the shaft portion, and the double-row ball bearing and the constant velocity joint are coupled to each other in such a manner that the double-row ball bearing and the constant velocity joint can transmit torque and are axially separable, and residual compression stress acts on the surfaces of the spur gears due to surface modification, it is possible toto increase fatigue strength while maintaining an intended shape and size without deformation caused by heat treatment, and to provide a high-quality, highly reliable drive wheel bearing device by increasing wear resistance.

[0017] If the face gear of the upset portion is preferentially formed by plastic deformation while the upset portion is being formed, it is possible to reduce the number of processing steps and reduce the cost.

[0018] The present invention relates to a drive wheel bearing device with a double-row ball bearing and a constant velocity joint that are detachably integrated. In the device, the double-row ball bearing includes: an outer member having a body mounting flange to be mounted on a vehicle body, the body mounting flange being integrally formed on the outer periphery and provided with an integrally formed double-row outer raceway surface on the inner periphery; an inner member formed from a wheel hub and a cylindrical inner ring member, the wheel hub having a wheel mounting flange for mounting a wheel, the wheel mounting flange being integrally formed at one end and having an inner raceway surface on its outer periphery that is disposed opposite the double-row outer raceway surface, and a cylindrical portion extending axially from the inner raceway surface.wherein the inner ring member is pressed onto the wheel hub and has on its outer periphery the other inner raceway surface arranged opposite the double-row outer raceway surface; and a double-row roller element that is freely rollable and accommodated between the raceways of the inner member and the outer member; and the constant velocity joint comprises an outer joint member having a cup-shaped mouth portion, a shoulder portion forming the bottom of the mouth portion, and a cylindrical shaft portion extending axially from the shoulder portion, wherein the shaft portion is provided with an internal thread, and wherein the mouth portion, the shoulder portion, and the shaft portion are integrally formed in the outer joint member, wherein spur gears are formed on the respective end surfaces of the shoulder portion of the outer joint member and the inner ring member,and wherein the spur gear teeth are supported by pressure by a fastening screw that bears against an outer end surface of the wheel hub and is screwed to the internal thread of the shaft portion, and wherein the double-row ball bearing and the constant velocity joint are coupled to each other in such a manner that the double-row ball bearing and the constant velocity joint can transmit torque and are axially separable, wherein the wheel hub and the inner ring member are plastically integrally coupled, and wherein a residual compressive stress acts on the surfaces of the spur gear teeth due to a surface modification.

[0019] As described above, in the drive wheel bearing device, since spur gears are formed on the respective end surfaces of the shoulder portion of the outer joint member and the inner ring member, the spur gears are supported by pressure by the fastening screw that abuts an outer end surface of the wheel hub and is screwed to the internal thread of the shaft portion, and the double-row ball bearing and the constant velocity joint are coupled to each other in such a manner that the double-row ball bearing and the constant velocity joint can transmit torque and are axially separable, the wheel hub and the inner ring member are plastically integrally coupled, and residual compression stress acts on the surfaces of the spur gears due to surface modification, it is possible to increase the fatigue strength and wear resistance while maintaining a desired shape and size.and to prevent fluctuations and the like due to a gap between the teeth of the spur gear or rework and thereby increase reliability.

[0020] If the end gearing of the inner ring member is preferentially formed while the inner ring member is formed by cold forging, it is possible to improve the material utilization.

[0021] Furthermore, by forming a stepped portion at one end of the inner ring member and forming the spur gear on a protruding end surface, it is possible to measure the size of a predetermined part by bringing a caliper of a measuring instrument into contact with the stepped portion. This makes it possible to easily adjust the amount of preload on the bearing.

[0022] Furthermore, by forming a hardened irregular portion on the inner circumference of the hub wheel and integrally plastically coupling the hub wheel and the inner ring member with a predetermined bearing preload applied by inserting a cylindrical portion of the inner ring member into the irregular portion and forcing the cylindrical portion into the irregular portion by expanding the diameter of the cylindrical portion, it is not necessary to adjust the amount of preload by tightening these parts with a nut or the like as in the prior art. This makes it possible to realize a reduction in weight and size, increase the strength and durability of the hub wheel, and maintain the amount of preload for a long time.

[0023] Furthermore, a cylindrical part of the inner ring member may be inserted into the wheel hub, and the wheel hub and the inner ring member may be plastically integrally coupled with a predetermined bearing preload generated by means of a swaged portion formed by plastically deforming one end of the cylindrical part radially outward.

[0024] Furthermore, if the fastening screw is screwed to the internal thread of the shaft section with a spacer interposed therebetween, and the spacer has a substantially L-shaped cross-section and includes a flange portion that abuts against an end surface of the wheel hub and a cylindrical portion that is slid and guided onto the fastening screw, it is possible to easily center the outer joint element and the inner element using the spacer. This simplifies the disassembly and assembly processes of the device. Furthermore, the spur gears can engage without circumferential and axial play.

[0025] Furthermore, by forming a radially inwardly projecting guide portion on the inner circumference of a cylindrical part of the inner ring member, and by inserting the fastening screw through the guide portion and screwing it into the internal thread of the shaft portion, it is possible to center the outer joint member and the inner member. This simplifies the disassembly and assembly processes of the device.

[0026] In addition, if the surface hardness of the spur gear is set to at least 300 Hv, it is possible to maximize the mechanical strength and fatigue strength of the material and increase the wear resistance.

[0027] Furthermore, the surface of the spur gear teeth can be shot peened or WPC treated for the purpose of surface modification.

[0028] Furthermore, laser-hardening the surface of the spur gear teeth prevents heat-treatment-induced deformation and increases the strength and wear resistance of the spur gear tooth surface, making it possible to enhance long-term reliability.

[0029] Furthermore, when one end of the cylindrical portion is formed as a hollow cylindrical part before upsetting, an annular groove having a predetermined depth is formed on an outer peripheral surface of the cylindrical part, ranging from a position corresponding to an end with a larger diameter of the inner raceway of the inner ring to a position above a larger end surface of the inner ring, and one end of the cylindrical part is plastically deformed so that a part of the annular groove is brought into direct contact with a chamfered portion of the inner ring and the remaining part has no contact with the inner ring and a gap is left, and the cylindrical part is easily deformed at the time of upsetting, an intended shape and size of the spur gear and the amount by which the inner ring is compressed are guaranteed,and the deformation of the inner ring due to oscillation compression is prevented, making it possible to increase longevity.

[0030] In addition, when the ring groove is formed in a region ranging from a position corresponding to the larger diameter end of the inner raceway of the inner ring to the chamfered portion on the larger end surface side, the region extending slightly beyond the larger end surface, the oscillation upsetting causes a state in which a part of the ring groove is brought into direct contact with a chamfered portion of the inner ring and the remaining part has no contact with the inner ring and a gap is left, thereby making it possible to guarantee a predetermined amount by which the inner ring is compressed and to prevent the deformation of the inner ring due to the oscillation upsetting.

[0031] In addition, if the bottom of the ring groove is formed as a tapered surface with a diameter that gradually decreases toward the tip of the cylindrical part and the inclination angle of the tapered surface is set to a maximum of 15°, it is possible to further reduce the hoop stress induced in the inner ring at the time of oscillation upsetting.

[0032] In addition, circular arc surfaces with radii of curvature Ri and Ro can be formed on the sides of the ring groove, and the radius of curvature Ri of the inside circular arc surface of the circular arc surfaces can be smaller than the radius of curvature Ro of the outside circular arc surface (Ri ≤ Ro) and can be set to a range of R1 to 10.

[0033] In addition, when a chamfered portion having a circular arc surface having a radius of curvature is formed at an inner diameter end on the larger end surface side of the inner ring and the radius of curvature of the chamfered portion is set in a range of R1.0 to 2.5, it is possible to prevent stress concentration from being generated at the root of the upset portion when a bending moment load is applied to the device while the vehicle is running, and to prevent excessive hoop stress from being generated in the inner ring due to oscillation upsetting.

[0034] Furthermore, if the depth of the ring groove is set to a depth of 0.5 to 2.0 mm, it is possible to guarantee an intended amount by which the inner ring is compressed while preventing the deformation of the inner ring.

[0035] In addition, when a hardened layer is formed in the cylindrical portion of the wheel hub by high frequency induction quenching to a surface hardness of 50 to 64 HRC and an inside edge of the hardened layer is arranged within a range from an outside starting point in the ring groove to 0 to 4.0 mm on the outside and on the inside to 0 to 3.0 mm in a range of an outside circular arc surface of the ring groove, it is possible to improve the workability of the cylindrical part in the cylindrical portion and prevent cracks or the like due to plastic deformation.

[0036] In addition, when two inner rings are pressed onto the cylindrical portion of the wheel hub, the positions of the inner raceways of the two inner rings are the same, and the length from the larger diameter end of the inner raceway of the inner ring on the upsetting side to the larger end surface is longer than the length from the larger diameter end of the inner raceway of the other inner ring to the larger end surface, it is possible to prevent the deformation of the inner ring on the upsetting side due to oscillation upsetting.

[0037] Furthermore, if a seal is mounted on the outer diameter of the inner ring or inner ring element; the seal includes a metal core pressed onto the outer diameter of the inner ring or inner ring element and a sealing element made of synthetic rubber; the sealing element is vulcanized to the metal core or integrally bonded thereto by a similar process and has an axial lip;and the axial lip elastically contacts the shoulder portion of the outer joint member, thereby sealing an engagement portion of the spur gears. It is possible to prevent foreign matter such as rainwater and dust from entering the engagement portion of the spur gears from the outside, and to achieve high sealing performance for a long time even if dimensional variations occur in the inner member or the outer joint member due to production or assembly errors, because the axial lip has sufficient elasticity. This makes it possible to improve workability at the time of disassembly and assembly.

[0038] When the sealing member has a lateral lip extending laterally radially outward; a stepped portion is formed in the shoulder portion of the outer joint member; and the lateral lip is brought into elastic contact with the stepped portion, even if dimensional variations occur due to production or assembly errors in the inner member or the outer joint member, it is possible to obtain high sealing performance by deforming the lateral lip and following the variations.

[0039] In addition, if the tip of the axial lip is formed into a circular arc shape, even if the wheel hub or the outer joint member is deformed due to a large applied moment load, it is possible to accurately follow this deformation, thereby making it possible to obtain high sealing performance.

[0040] In addition, if the sealing element has a grease lip and the engagement portion of the spur gears is filled with grease, the grease lip can prevent grease leakage with absolute certainty, thereby making it possible to prevent wear of the spur gears.

[0041] Furthermore, as in the present invention, when an outer seal is mounted on the outer diameter of the shoulder portion of the outer joint member; the outer seal includes a cylindrical metal core pressed onto the outer diameter of the shoulder portion, and a sealing member vulcanized to the metal core or integrally bonded thereto by a similar method;By bringing a lip of the sealing member into elastic contact with the inner member or an inside seal of the seal, thereby sealing the engagement portion of the spur gears, it is possible to prevent foreign matter such as rainwater and dust from entering the engagement portion of the spur gears from the outside, and to achieve high sealing performance for a long time even if dimensional variations occur in the inner member or the outer joint member due to production or assembly errors, because the sealing lip has sufficient elasticity. This makes it possible to improve workability at the time of disassembly and assembly.

[0042] When the sealing element has split side lips extending radially laterally, and the side lips are brought into elastic contact with the larger end surface of the inner ring, even if dimensional variations occur in the inner element or the outer joint element due to production or assembly errors, it is possible to obtain high sealing performance by deforming the side lip and following the variations.

[0043] Furthermore, when the sealing member has an axial lip with a circular arc-shaped tip and the axial lip is brought into elastic contact with the larger end surface of the inner ring, even if the wheel hub or the outer joint member is deformed due to a large applied moment load, it is possible to accurately follow this deformation, thereby making it possible to obtain high sealing performance.

[0044] Furthermore, when the sealing member has a pair of dividing radial lips and the radial lips are brought into elastic contact with the outer diameter of the inner ring, even if the wheel hub or the outer joint member is deformed due to a strong applied moment load, it is possible to accurately follow this deformation, thereby making it possible to obtain high sealing performance.

[0045] Furthermore, as in the present invention, when the inside seal is formed as a packing seal provided with an annular seal plate and a scraper ring having a substantially L-shaped cross section; the seal plate is formed of a metal core fitted into the end of the outer member, the metal core having a substantially L-shaped cross section, and a sealing element vulcanized to the metal core, the scraper ring being formed of a cylindrical part pressed onto the outer diameter of the inner ring and an upright portion extending radially outward from the cylindrical part; the sealing element of the outer seal has a lateral lip extending laterally radially outward and a radial lip extending laterally radially inward;the lateral lip is brought into elastic contact with a side surface of the upright portion of the scraper ring, and the radial lip is brought into elastic contact with the outer diameter of the inner ring, it is possible to prevent foreign matter such as rainwater and dust from entering the engagement portion of the spur gears from the outside, and to prevent foreign matter such as rainwater and dust from entering the bearing through a fitting portion between the scraper ring and the inner ring, thereby increasing the durability of the bearing.; EFFECTS OF THE PRESENT INVENTION

[0046] A drive wheel bearing device according to the present invention is a drive wheel bearing device as defined in claim 1. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a longitudinal sectional view showing a first embodiment of a drive wheel bearing device; Fig. 2 is a longitudinal sectional view showing a storage unit of Fig. 1 shows; Fig. 3 is a longitudinal sectional view showing a constant velocity joint of Fig. 1 shows; Fig. 4 is a longitudinal sectional view showing a second embodiment of the drive wheel bearing device; Fig. 5 is a longitudinal sectional view showing a storage unit of Fig. 4 shows; Fig. 6 is a longitudinal sectional view showing a third embodiment of the drive wheel bearing device; Fig. 7 is a longitudinal sectional view showing a storage unit of Fig. 6 shows; Fig. 8 is a longitudinal sectional view showing a fourth embodiment of the drive wheel bearing device; Fig. 9 is a longitudinal sectional view showing a fifth embodiment of the drive wheel bearing device; Fig. 10 is a longitudinal sectional view showing a storage unit of Fig. 9 shows; Fig. 11 is a longitudinal sectional view showing a storage unit of Fig. 10 shows the bearing unit in the state before oscillation compression; Fig. 12 is an enlarged view of the main section of Fig. 11; Fig. 13 is an enlarged view of the main portion showing a modified embodiment of Fig. 12 shows; Fig. 14 is a longitudinal sectional view showing a sixth embodiment of the drive wheel bearing device; Fig. 15 is a longitudinal sectional view showing a seventh embodiment of the drive wheel bearing device; Fig. 16 is a longitudinal sectional view showing a storage unit of Fig. 15 shows; Fig. 17 is an enlarged view of the main section showing a sealing section of Fig. 15 shows; Fig. 18 is an enlarged view of the main section showing a modified example of a gasket of Fig. 17 shows; Fig. 19 is a longitudinal sectional view showing an eighth embodiment of the drive wheel bearing device; Fig. 20 is a longitudinal sectional view showing a ninth embodiment of the drive wheel bearing device; Fig. 21 is a longitudinal sectional view showing a tenth embodiment of the drive wheel bearing device according to the present invention; Fig. 22 is a longitudinal sectional view showing a constant velocity joint of Fig. 21 shows; Fig. 23 is an enlarged view of the main section showing an outer seal section of Fig. 21 shows; Fig. 24 is an enlarged view of the main section showing a modified example of an outer seal of Fig. 23 shows; Fig. 25 is an enlarged view of the main section showing another modified example of the outer seal of Fig. 23 shows; Fig. 26 is an enlarged view of the main section showing another modified example of the outer seal of Fig. 23 shows; Fig. 27 is a longitudinal sectional view showing an eleventh embodiment of the drive wheel bearing device; Fig. Fig. 28 is a longitudinal sectional view showing a twelfth embodiment of the drive wheel bearing device; and Fig. 29 is a longitudinal sectional view showing a prior art drive wheel bearing device. BEST MODES FOR CARRYING OUT THE PRESENT INVENTION AND OTHER EMBODIMENTS

[0047] In a drive wheel bearing device with a double-row ball bearing and a constant velocity joint which are detachably integrated, the double-row ball bearing in the drive wheel bearing device contains the features of patent claim 1. First embodiment

[0048] Hereinafter, embodiments of the present invention and non-invention embodiments are described in detail with reference to the drawings.

[0049] Fig. 1 is a longitudinal sectional view showing a first embodiment of a drive wheel bearing device; Fig. 2 is a longitudinal sectional view showing a storage unit of Fig. 1 shows; and Fig. 3 is a longitudinal sectional view showing a constant velocity joint of Fig. 1. In the following description, a side that tends towards the outside of a vehicle is referred to as an outside (the left side in Fig. 1), and a side that tends towards the center of the vehicle is called an inside (the right side in Fig. 1) when the device is mounted on a vehicle.

[0050] This drive wheel bearing device has a structure referred to as the "third generation." It detachably integrates a wheel hub 1, a double-row ball bearing 2, and a constant velocity joint 3. The double-row ball bearing 2 includes an outer element 7, an inner element 8, and double-row rolling elements (balls) 9 and 9.

[0051] The outer member 7 is made of medium-high carbon steel containing 0.40 to 0.80 wt% carbon, the medium-high carbon steel being, for example, S53C; has a body mounting flange 7b to be mounted on a vehicle body (not shown), the body mounting flange 7b being integrally formed on the outer circumference; and has integrally formed double-row outer raceways 7a and 7a on the inner circumference. Furthermore, at least the double-row outer raceways 7a and 7a are hardened by high-frequency induction quenching to a surface hardness of 58 to 64 HRC.

[0052] On the other hand, double-row inner raceways 1a and 5a are formed on the inner member 8, and the double-row inner raceways 1a and 5a are disposed opposite the outer raceways 7a and 7a of the outer member 7. Of the double-row inner raceways 1a and 5a, the inner raceway 1a (outer side) is formed integrally with the outer periphery of the wheel hub 1, and the inner raceway 5a (inner side) is formed integrally with the outer periphery of the inner ring 5. In this case, the inner member 8 refers to the wheel hub 1 and the inner ring 5. In addition, the double-row rolling elements 9 and 9 are accommodated between the raceways and are held in a rolling manner by cages 10 and 10. Furthermore, seals 11 and 12 are mounted at the opening of an annular space formed between the outer element 7 and the inner element 8 and prevent the leakage of grease contained in the bearing and the ingress of rainwater, dust, etc.into the camp from outside.

[0053] As shown in an enlarged view of Fig. 2, the wheel hub 1 has a wheel mounting flange 4 for mounting a wheel (not shown). The wheel mounting flange 4 is integrally formed at an outboard end and is provided with a cylindrical portion 1b on the outer circumference, the cylindrical portion 1b extending axially from the inner raceway 1a. The wheel hub 1 is made of medium-high carbon steel containing 0.40 to 0.80 wt% carbon, the medium-high carbon steel being, for example, S53C; and an outer peripheral surface including the inner raceway 1a is hardened from an inboard base 4a of the wheel mounting flange 4, the base 4a serving as a seal abutment portion of the outboard seal 11, to the cylindrical portion 1b by high-frequency induction quenching to a surface hardness of 58 to 64 HRC.This not only increases the wear resistance of the seal contact section but also further increases the durability of the wheel hub 1 because the wheel hub 1 has sufficient mechanical strength to withstand rotational bending loads acting on the wheel mounting flange 4. The inner ring 5 and the rolling element 9 are made of high-carbon chromium steel, such as SUJ2, and are through-hardened by quenching to a hardness of 58 to 64 HRC.

[0054] The inner ring 5 is pressed onto the cylindrical portion 1b of the wheel hub 1 through a predetermined interference fit and is axially fixed with an intended bearing preload generated by a swaged portion 13 formed by plastically deforming the end of the cylindrical portion 1b. A spur gear 13a is formed by plastic deformation on the end surface of the swaged portion 13 when oscillation swaging is performed. In this case, a double-row angular contact ball bearing with a ball as the rolling element 9 is shown as an example; however, the embodiment is not limited to this. A double-row tapered roller bearing with a tapered roller as the rolling element 9 can also be used.

[0055] As shown in an enlarged view of Fig. 3, the constant velocity joint 3 consists of an outer joint member 14, a joint inner ring 15, a cage 16, and a torque transmitting ball 17. The outer joint member 14 has a cup-shaped mouth portion 18, a shoulder portion 19 forming the bottom of the mouth portion 18, and a cylindrical shaft portion 20 extending axially from the shoulder portion 19. Curved, axially extending ruts 18a and 15a are formed on the inner periphery of the mouth portion 18 and the outer periphery of the joint inner ring 15, respectively. Furthermore, a spur gear 19a is formed on the end surface of the shoulder portion 19, which engages with the spur gear 13a of the swaged portion 13, and an internal thread 20a is formed in the shaft portion 20.The outer joint member 14 is made of medium-high carbon steel containing 0.40 to 0.80 wt% carbon, the medium-high carbon steel being, for example, S53C; and the rut 18a is hardened by high-frequency induction quenching to a surface hardness of 58 to 64 HRC.

[0056] Furthermore, as in Fig. 1, a fastening screw 21 is screwed into the internal thread 20a of the shaft portion 20, and the spur gear teeth 19a and 13a of the shoulder portion 19 of the outer joint member 14 and the swaged portion 13 of the wheel hub 1 (with the spur gear teeth 19a and 13a being arranged opposite each other) are supported by pressure by the fastening screw 21, thereby detachably integrating the double-row ball bearing 2 and the constant velocity joint 3. In this embodiment, since a smaller-diameter portion 1c, into which the fastening screw 21 is inserted through a predetermined guide clearance, is arranged in the inner diameter of the wheel hub 1, it is possible to easily center the outer joint member 14 and the inner member 8. This simplifies the disassembly and assembly processes of the device and allows engagement of the spur gears 19a and 13a without circumferential and axial play.

[0057] As a result of surface modification by shot peening, residual compressive stress acts on the end teeth 13a of the upset portion 13 and the end teeth 19a of the shoulder portion 19 of the outer joint member 14. This makes it possible to increase fatigue strength while maintaining a desired shape and size without deformation caused by heat treatment. A steel ball with a grain size in the mid- to high double-digit micrometer range up to 0.1 mm is used as the shot peening grit. In addition to steel balls, non-ferrous balls such as ceramics can also be used. Shot peening is carried out under the following conditions: a pressure of 0.4 MPa, a processing time of 20 seconds, and an ejection distance of 100 mm.

[0058] In the test conducted by the applicant using specimens of S53C to S55C, it was found that, although there are slight differences in the residual compressive stress depending on the shot peening grain or deposition conditions, it is possible to achieve a residual compressive stress of 500 MPa at the surface by setting the surface hardness of a surface where stress is induced to at least about 300 HV, and it is possible to induce a residual compressive stress of about 1000 MPa at the uppermost surface layer by setting the surface hardness to at least 520 HV. This makes it possible to form the spur gear 13a also by plastic deformation of the upset portion 13, and even if a residual tensile stress is induced at the surface, a sufficient residual compressive stress is still generated on that surface.As a result, it is possible to maximize the mechanical strength and fatigue strength of the material.

[0059] In addition to shot peening, WPC (Wide Peening Cleaning) can also be used to create residual compressive stress. In this process, the shot peening grit is finer than in shot peening and impacts the surface where stress is to be created at a higher speed. WPC makes it possible to further increase fatigue strength and wear resistance, resulting in a high-quality, highly reliable drive wheel bearing device.

[0060] Furthermore, the surfaces of the spur gears 13a and 19a can be laser hardened. This makes it possible to prevent deformation caused by heat treatment and increase the strength and wear resistance of the tooth surfaces of the spur gears 13a and 19a. This makes it possible to increase reliability over a long period of time.

[0061] As already mentioned, both end gears 13a and 19a can be hardened by shot peening, WPC, or laser hardening; however, the embodiments are not limited thereto. Shot peening, WPC, and laser hardening can be combined in an appropriate manner. For example, the surface of the end gear 13a of the upset portion 13 can be hardened by laser hardening, and shot peening can be performed on the end gear 19a of the shoulder portion 19. Second embodiment

[0062] Fig. 4 is a longitudinal sectional view showing a second embodiment of the drive wheel bearing device, and Fig. 5 is a longitudinal sectional view showing a storage unit of Fig. 4. This embodiment differs from the above-described first embodiment basically only in the structure of the double-row ball bearing, and therefore, components and parts identical or functionally equivalent to those in the first embodiment are designated by the same reference numerals; and their detailed description will be omitted.

[0063] This drive wheel bearing device has a structure referred to as the "third generation." It detachably integrates a wheel hub 22, a double-row ball bearing 23, and a constant velocity joint 3. The double-row ball bearing 23 includes an outer element 7, an inner element 24, and double-row rolling elements 9 and 9.

[0064] As shown in an enlarged view of Fig. 5, the inner member 24 is formed with double-row inner raceways 1a and 5a, which are disposed opposite outer raceways 7a and 7a of the outer member 7. Of the double-row inner raceways 1a and 5a, the inner raceway 1a (outer side) is integrally formed on the outer periphery of the wheel hub 22, and the inner raceway 5a (inner side) is integrally formed on the outer periphery of an inner ring member 25. In this case, the inner member 24 refers to the wheel hub 22 and the inner ring member 25.

[0065] The wheel hub 22 has a wheel mounting flange 4 integrally formed at its outboard end; a cylindrical portion 22a formed on its outer periphery, the cylindrical portion 22a extending axially from the inner raceway 1a; and, on its inner periphery, an irregular portion 26 (shown by hatching in the drawing) hardened by high-frequency induction quenching to a surface hardness of 58 to 64 HRC. The irregular portion 26 is in the form of cross-patterned knurls and consists of intersecting grooves formed by a plurality of annular grooves (machined independently by turning or the like) and a plurality of axial grooves (machined by broaching or the like) that intersect at nearly right angles, or consists of intersecting grooves formed by obliquely extending spiral grooves.Furthermore, the tip of the convex portion of the irregular portion 26 is pyramid-shaped, for example triangular, to ensure a tight fit.

[0066] The wheel hub 22 is made of medium-high carbon steel containing 0.40 to 0.80 wt% carbon, where the medium-high carbon steel is, for example, S53C; and an outer peripheral surface including the inner raceway 1a is hardened from an inside base 4a of the wheel mounting flange 4 to the cylindrical portion 22a by high-frequency induction quenching to a surface hardness of 58 to 64 HRC (shown by hatching in the drawing). This not only increases the wear resistance of the base 4a, i.e., a seal abutment portion, of the wheel mounting flange 4, but also increases the durability of the wheel hub 22 because the wheel hub 22 has sufficient mechanical strength to withstand a rotational bending load acting on the wheel mounting flange 4.

[0067] The inner ring member 25 is integrally formed with a cylindrical portion 27 extending axially from the inner raceway 5a. The cylindrical portion 27 is comprised of a journal portion 27a that is press-fitted into the cylindrical portion 22a of the wheel hub 22, and a fitting portion 27b formed at the end of the journal portion 27a and disposed opposite the irregular portion 26 of the wheel hub 22. Furthermore, a stepped portion 28 is formed on the inner end surface of the inner ring member 25, and a spur gear 25a is formed on the end surface of the stepped portion 28.The inner ring member 25 is made of medium-high carbon steel containing 0.40 to 0.80 wt% carbon, for example, S53C; and a region from the inner raceway 5a to the journal portion 27a is hardened by high-frequency induction quenching to a surface hardness of 58 to 64 HRC (shown by hatching in the drawing). The hardness of the fitting portion 27b remains the same as a material hardness obtained after forging.

[0068] Here, the wheel hub 22 and the inner ring member 25 are plastically integrally coupled with an intended bearing preload caused by upsetting, wherein the fitting portion 27b is pressed and caulked into the irregular portion 26 of the wheel hub 22 by fitting the cylindrical part 27 of the inner ring member 25 into the wheel hub 22, and at the same time, the diameter of the fitting portion 27b is expanded by pressing a diameter-enlarging tool such as a mandrel into the fitting portion 27b. This eliminates the need to adjust the amount of preload by tightening it with a nut or the like, as is the case in the prior art. Therefore, it is possible to realize a reduction in weight and size, increase the strength and durability of the wheel hub 22, and maintain the amount of preload for a long time.

[0069] Furthermore, in this embodiment, the inner ring member 25 including the spur gear 25a is formed by cold forging. Then, the member is turned to a predetermined shape and size, and after a predetermined portion is subjected to heat treatment, residual compressive stress is induced on the spur gear 25a by surface modification through shot peening. Thereafter, at least the inner raceway 5a is ground. This makes it possible to avoid problems caused by forming the spur gear 13a in finished products while simultaneously forming the upset portion 13, as in the case of the first embodiment described above, that is, variations due to a gap between the teeth of the spur gear 13a or repeated machining, or a reduction in durability due to hoop stress induced in the inner ring 5.This makes it possible to achieve greater reliability and avoid the cost increase that results from the scrapping of finished products due to the problems described above.

[0070] Here, as in Fig. 4, a fastening screw 21 is screwed into an internal thread 20a of a shaft portion 20, and the spur gear teeth 19a and 25a of the outer joint member 14 and the inner member 24 (with the spur gear teeth 19a and 25a being arranged opposite each other) are supported by pressure by the fastening screw 21 with a spacer 29 interposed therebetween, thereby detachably integrating the double-row ball bearing 23 and the constant velocity joint 3. The spacer 29 is formed with a substantially L-shaped cross section and has a flange portion 29a that abuts against the outer end surface of the wheel hub 22 and a cylindrical part 29b that is slid onto the fastening screw 21. As a result, it is possible to easily center the outer joint member 14 and the inner member 24 by means of the spacer 29. This simplifies the disassembly and assembly processes of the device.In addition, the spur gear teeth 19a and 25a can engage without circumferential and axial play.

[0071] As described above, since the spur gear 25a has no backlash thanks to the spacer 29 and is subjected to residual compressive stress due to surface modification by shot peening, the spur gear 25a hardly wears due to repeated contact. Furthermore, the spur gear 25a is formed by cold forging here to improve material utilization; however, the embodiment is not limited to this. The spur gear 25a can also be formed by turning after the inner ring member 25 is formed by hot forging, or the spur gear 25a can be formed by plastic deformation after turning, such as orbital forging. Third embodiment

[0072] Fig. Fig. 6 is a longitudinal sectional view showing a third embodiment of the drive wheel bearing device, and Fig. 7 is a longitudinal sectional view showing a storage unit of Fig. 6. Note that components and parts identical or functionally equivalent to those in the above-described embodiments are denoted by the same reference numerals; and their detailed description will be omitted.

[0073] As in Fig. 6, this drive wheel bearing device has a structure referred to as the "third generation." A wheel hub 30, a double-row ball bearing 31, and a constant velocity joint 3 are detachably integrated therein. As shown in an enlarged view of Fig. 7, the double row ball bearing 31 includes an outer member 7, an inner member 32, and double row rolling elements 9 and 9. The inner member 32 consists of the wheel hub 30 and an inner ring member 33 fitted into the wheel hub 30, and is provided with double row inner raceways 1a and 5a disposed opposite outer raceways 7a and 7a of the outer member 7.

[0074] The wheel hub 30 has a wheel mounting flange 4 integrally formed at its outer end and has, on its outer periphery, a cylindrical portion 22a extending axially from the inner raceway 1a. The wheel hub 30 is made of medium-high carbon steel containing 0.40 to 0.80 wt% carbon, where the medium-high carbon steel is, for example, S53C; and an outer peripheral surface including the inner raceway 1a is hardened from an inner base 4a of the wheel mounting flange 4 to the cylindrical portion 22a—together with an inner peripheral surface—by high-frequency induction quenching to a surface hardness of 58 to 64 HRC (only a hardened portion of the inner peripheral surface is shown hatched in the drawing).

[0075] The inner ring member 33 is integrally formed with a cylindrical portion 34 extending axially from the inner raceway surface 5a. Furthermore, the inner ring member 33 and the wheel hub 30 are plastically coupled integrally with a predetermined bearing preload generated by a swaged portion 34a formed by plastically deforming the end of the cylindrical portion 34 radially outward. The inner ring member 33 is made of medium-high carbon steel containing 0.40 to 0.80 wt% carbon, the medium-high carbon steel being, for example, S53C; and an outer diameter surface from the inner raceway surface 5a to the cylindrical portion 34 is hardened by high-frequency induction quenching to a surface hardness of 58 to 64 HRC (shown by hatching in the drawing).The hardness of the end of the cylindrical part 34 undergoing plastic deformation remains the same as the material hardness obtained after forging, and the hardness of the upset portion 34a is adjusted to 15 to 35 HRC, including plastic hardening. This makes it possible to easily perform plastic deformation and thereby prevent the formation of microcracks due to plastic deformation. At the same time, it is possible to guarantee the strength of the upset portion 34a and thus maintain a strong connection for a long time.

[0076] In this embodiment, the inner ring member 33, which includes the spur gear teeth 25a, is formed by cold forging. The member is then turned to a predetermined shape and size, and after a predetermined portion is subjected to heat treatment, the spur gear teeth 25a are shot peened. Then, at least the inner raceway 5a is ground.

[0077] Here, as in Fig. 6, a fastening screw 21 is screwed into an internal thread 20a of a shaft portion 20, and the spur gear teeth 19a and 25a of the outer joint member 14 and the inner member 32 (with the spur gear teeth 19a and 25a being arranged opposite each other) are supported by pressure by the fastening screw 21 with a spacer 35 interposed therebetween, thereby detachably integrating the double-row ball bearing 31 and the constant velocity joint 3. The spacer 35 has a substantially L-shaped cross section and includes a flange portion 35a that abuts against the end surface of the swaged portion 34a and a cylindrical portion 35b that is slid onto the fastening screw 21. As a result, it is possible to easily center the outer joint member 14 and the inner member 32 by means of the spacer 35. This simplifies the disassembly and assembly processes of the device.In addition, it is possible to replace the double-row ball bearing and the constant velocity joint separately with a new one, without having to replace them as a unit (as in a "fourth generation" setup), thus contributing to cost reduction. Fourth embodiment

[0078] Fig. Fig. 8 is a longitudinal sectional view showing a fourth embodiment of the drive wheel bearing device. This embodiment differs from the third embodiment described above ( Fig. 6) basically only in a part of the structure of the inner ring member, and therefore, components and parts that are identical or functionally equivalent to those in the third embodiment will be designated by the same reference numerals; and their detailed description will be omitted.

[0079] This drive wheel bearing device has a structure referred to as the "third generation." It detachably integrates a wheel hub 30, a double-row ball bearing 36, and a constant velocity joint 3. The double-row ball bearing 36 includes an outer member 7, an inner member 37, and double-row rolling elements 9 and 9. The inner member 37 consists of the wheel hub 30 and an inner ring member 38 fitted into the wheel hub 30, and is provided on its outer periphery with double-row inner raceway surfaces 1a and 5a, which are arranged opposite outer raceway surfaces 7a and 7a of the outer member 7.

[0080] The inner ring member 38 is integrally formed with a cylindrical portion 39 extending axially from the inner raceway surface 5a. Furthermore, the inner ring member 38 and the wheel hub 30 are plastically coupled integrally with a predetermined bearing preload generated by a swaged portion 34a formed by plastically deforming the end of the cylindrical portion 39 radially outward. The inner ring member 38 is made of medium-high carbon steel containing 0.40 to 0.80 wt% carbon, the medium-high carbon steel being, for example, S53C; and an outer diameter surface from the inner raceway surface 5a to the cylindrical portion 39 is hardened by high-frequency induction quenching to a surface hardness of 58 to 64 HRC (shown by hatching in the drawing).

[0081] Here, a radially inwardly projecting guide portion 39a is formed on the inner circumference of the cylindrical part 39 of the inner ring member 38. Furthermore, a fastening screw 40 is inserted through the guide portion 39a and screwed into an internal thread 20a of the shaft portion 20. The spur gears 19a and 25a of the outer joint member 14 and the inner member 37 are supported by pressure by the fastening screw 40, thereby detachably integrating the double-row ball bearing 36 and the constant velocity joint 3. As a result, unlike the embodiments described above, it is possible to center the outer joint member 14 and the inner member 37 without installing the spacers 29 and 35, thereby simplifying the disassembly and assembly procedures of the device. Fifth embodiment

[0082] Fig. 9 is a longitudinal sectional view showing a fifth embodiment of the drive wheel bearing device; Fig. 10 is a longitudinal sectional view showing a storage unit of Fig. 9 shows; Fig. 11 is a longitudinal sectional view showing a storage unit of Fig. 10 shows the bearing unit in the state before oscillation compression; Fig. 12 is an enlarged view of the main section of Fig. 11; and Fig. 13 is an enlarged view of the main section showing a modified example of Fig. 12. This embodiment differs from the previously described first embodiment ( Fig. 1) basically only in a part of the structure of the inner member, and therefore, components and parts that are identical or functionally equivalent to those in the first embodiment are designated by the same reference numerals and their detailed description is omitted.

[0083] This drive wheel bearing device has a structure referred to as the "third generation." It integrates a wheel hub 41 and a double-row ball bearing 42, and a constant velocity joint 3 is axially detachably connected thereto. The double-row ball bearing 42 includes an outer element 7, an inner element 43, and double-row rolling elements 9 and 9.

[0084] The outer member 7 is made of medium-high carbon steel containing 0.40 to 0.80 wt% carbon, the medium-high carbon steel being, for example, S53C, and has a body mounting flange 7b to be mounted on a vehicle body (not shown), the body mounting flange 7b being integrally formed on the outer circumference, and has double-row outer raceways 7a and 7a integrally formed on the inner circumference. Furthermore, at least in the double-row outer raceways 7a and 7a, a predetermined hardened layer is formed, which is hardened by high-frequency induction quenching to a surface hardness of 58 to 64 HRC (in Fig. 11 hatched).

[0085] On the other hand, the inner member 43 is formed with double-row inner raceways 1a and 5a, which are arranged opposite to the outer raceways 7a and 7a of the outer member 7. Of the double-row inner raceways 1a and 5a, the inner raceway 1a (outer side) is formed directly on the outer periphery of the wheel hub 41, and the inner raceway 5a (inner side) is formed on the outer periphery of the inner ring 5. In this case, the inner member 43 refers to the wheel hub 41 and the inner ring 5. Furthermore, the double-row rolling elements 9 and 9 are accommodated between the raceways and are held in a rolling manner by cages 10 and 10.

[0086] As shown in an enlarged view of Fig. As shown in Figure 10, the wheel hub 41 has a wheel mounting flange 4 integrally formed at the outboard end, has an inner raceway 1a on its outer periphery, and has a cylindrical portion 1b extending axially from the inner raceway 1a. The wheel hub 41 is made of medium-high carbon steel containing 0.40 to 0.80 wt% carbon, where the medium-high carbon steel is, for example, S53C; and on an outer peripheral surface—from an inboard base 4a of the wheel mounting flange 4 (the base 4a serving as a seal abutment portion of an outboard seal 11) to the cylindrical portion 1b—a hardened layer 46 is formed, which is hardened by high-frequency induction quenching to a surface hardness of 58 to 64 HRC (hatched in Fig. 11). The surface hardness of the inner raceway 1a is set to 58 to 64 HRC, and the hardness of a swaged portion 13, as described later, remains the same as the hardness (13 to 30 HRC) obtained after forging. This not only increases the wear resistance of the seal abutment portion but also increases the durability of the wheel hub 41 because the wheel hub 41 has sufficient mechanical strength to withstand a rotational bending load acting on the wheel mounting flange 4.

[0087] Spur gear teeth 19a and 13a of a shoulder portion 19 of an outer joint member 14 and the swaged portion 13 of the wheel hub 41 (the spur gear teeth 19a and 13a being arranged opposite each other) are supported by pressure by screwing a fastening screw 21 into an internal thread 20a of a shaft portion 20, as shown in Fig. 9, whereby the double-row ball bearing 42 and the constant velocity joint 3 are detachably integrated.

[0088] Here is how in Fig. 11, the cylindrical portion 1b of the wheel hub 41 is formed as a cylindrical part 44 having a nearly uniform thickness before plastic deformation. At the end of the cylindrical part 44, circular arc-shaped chamfered portions 44a and 44b are formed. Furthermore, as shown in an enlarged view of Fig. 12, a chamfered portion 5c having a circular arc surface with a radius of curvature ri of R1.0 to 2.5 is formed at the inner diameter end on the larger end surface 5b side (the upset portion side) of the inner ring 5. If the radius of curvature ri of the chamfered portion 5c is set to a value smaller than 1.0 mm, there is a possibility of stress concentration at the root of the upset portion 13 when a bending moment load is applied to the device while the vehicle is running, causing damage such as microcracks. However, a radius of curvature ri larger than 2.5 mm is also undesirable because the inner ring 5 is expanded radially outward when the cylindrical part 44 is plastically deformed, thereby generating excessive hoop stress on the outer diameter of the inner ring 5.

[0089] Furthermore, an annular groove (undercut) 45 with a depth t is formed on the outer peripheral surface of the cylindrical part 44. The annular groove 45 is formed in a region ranging from a position corresponding to the larger-diameter end of the inner raceway 5a in the inner ring 5 to the chamfered portion 5c of the inner ring 5, extending slightly beyond the larger end surface 5b. Furthermore, a circular arc surface 45a with a radius of curvature Ri and a circular arc surface 45b with a radius of curvature Ro are formed on the sides of the annular groove 45.

[0090] In this embodiment, the depth t of the annular groove 45 is set to 0.5 to 2.0 mm; the radius of curvature Ri of the inner side circular arc surface 45a is set to be larger than the radius of curvature ri of the chamfered portion 5c of the inner ring 5 and smaller than the radius of curvature Ro of the outer side circular arc surface 45b (ri ≤ Ri ≤ Ro); and Ri = R1 to 10. As described above, by forming the annular groove 45 on the outer peripheral surface of the cylindrical part 44, the cylindrical part 44 is easily deformed when the upsetting is performed, thereby making it possible to prevent the deformation of the inner ring 5. However, the effectiveness is reduced when the depth t of the annular groove 45 is smaller than 0.5 mm; and if the depth t exceeds 2.0 mm, the inner ring is compressed by an insufficient amount, making it impossible to obtain the intended force with which the inner ring 5 is fixed.That is, even if a part of the annular groove 45 is brought into direct contact with the chamfered portion 5c of the inner ring 5, the space of the annular groove 45 remains after upsetting.

[0091] Furthermore, the inner edge of the hardened layer 46 formed on the outer periphery of the wheel hub 41 is positioned within a range from the starting point of the outer circular arc surface 45b in the annular groove 45 to 4.0 mm on the outer side and 3.0 mm on the inner side in a range of the circular arc surface 45b (the range in the annular groove 45). By positioning the position of the inner edge of the hardened layer 46 in the above-described range, the amount by which the diameter of the fitting portion of the inner ring of the cylindrical portion 1b is expanded by upsetting is reduced, thereby making it possible to reduce the hoop stress of the inner ring 5. Furthermore, the initial position of the expanded diameter part can be brought closer to the upset portion 13, thereby making it possible to improve the upsetting ability of the cylindrical part 44 in the cylindrical portion 1b.Furthermore, by disposing the inner edge of the hardened layer 46 within a range of the circular arc surface 45b, it is possible to prevent cracks or the like from being generated due to the plastic deformation of the hardened layer 46.

[0092] Since, as described above, in this embodiment, the end of the cylindrical portion 1b in the wheel hub 41 before upsetting is formed as the hollow cylindrical part 44; the annular groove 45 having a predetermined depth t is formed on the outer peripheral surface of the cylindrical part 44; the circular arc surface 45a having a predetermined radius of curvature Ri and the circular arc surface 45b having a predetermined radius of curvature Ro are formed on the sides of the annular groove 45;and the width of the annular groove 45 is set within a predetermined range, it is possible to provide a drive gear bearing device in which the cylindrical part 44 is easily deformed at the time of upsetting, an intended shape and size of the spur gear 13a is obtained, and the inner ring 5 is compressed by an intended amount, so that the durability of the device is increased by preventing deformation of the inner ring 5 due to oscillation upsetting.;

[0093] Fig. 13 is a modified example of the Fig. 12. This embodiment differs from the above-described embodiment basically only in the shape of the annular groove, and therefore, components and parts identical to those of the above-described embodiment are designated by the same reference numerals, and duplicate descriptions are omitted.

[0094] The cylindrical portion 1b of the wheel hub 41 is formed as a cylindrical part 44 with a nearly uniform thickness before plastic deformation. An annular groove 45' with a depth t is formed on the outer peripheral surface of the cylindrical part 44. The annular groove 45' is formed in a region ranging from a position corresponding to the larger-diameter end of the inner raceway 5a in the inner ring 5 to the chamfered portion 5c of the inner ring 5, extending slightly beyond the larger end surface 5b. Furthermore, a circular arc surface 45a with a radius of curvature Ri and a circular arc surface with a radius of curvature Ro are formed on the sides of the annular groove 45'.

[0095] Here, the bottom of the annular groove 45' is formed as a tapered surface with a diameter that gradually decreases toward the tip of the cylindrical part 44, and the inclination angle θ of the tapered surface is set to a maximum of 15°, more preferably a maximum of 10°. As a result, it is possible to further reduce the hoop stress induced in the inner ring 5 at the time of oscillation upsetting. An inclination angle θ of more than 15° is undesirable because it causes the cylindrical part 44 to become thinner, resulting in a reduction in strength. Sixth embodiment

[0096] Fig. 14 is a longitudinal sectional view showing a sixth embodiment of the drive gear bearing device. This embodiment differs from the above-described fifth embodiment basically only in the structure of the double-row ball bearing. Therefore, components and parts identical or functionally equivalent to those in the fifth embodiment are denoted by the same reference numerals; and their detailed description will be omitted.

[0097] This drive wheel bearing device has a structure referred to as the "second generation." It consists of a wheel hub 47 and a wheel bearing 48 formed of a double-row ball bearing mounted on the wheel hub 47. The wheel bearing 48 has a body mounting flange 7b integrally formed on the outer periphery and includes: an outer member 7 having double-row outer raceways 7a and 7a integrally formed on its inner periphery; two inner rings 49 and 50 having inner raceways 5a and 5a formed on their outer peripheries, the inner raceways 5a and 5a being disposed opposite the double-row outer raceways 7a and 7a; and double-row rolling elements 9 and 90 rollably received between the raceways with cages 10 and 10 interposed therebetween. Seals 50 and 12 are mounted at the opening of an annular space formed between the outer element 7 and the two inner rings 49 and 5.This prevents the grease contained in the bearing from leaking out and prevents rainwater, dust, etc. from entering the bearing from the outside.

[0098] The wheel hub 47 has a wheel mounting flange 4 integrally formed at the outer end and is provided with a cylindrical portion 47b extending axially from the wheel mounting flange 4 via the shoulder portion 47a. Furthermore, the wheel bearing 48 is pressed onto the cylindrical portion 47b of the wheel hub 47 with a predetermined interference fit until the wheel bearing 48 abuts against the shoulder portion 47a, and is axially secured in a state where an intended bearing preload is generated by means of a swaged portion 51 formed by plastically deforming the end of the cylindrical portion 47b. Furthermore, a spur gear 51a is milled on the end surface of the swaged portion 51 after oscillation swaging.

[0099] The wheel hub 47 is made of medium-high carbon steel containing 0.40 to 0.80 wt% carbon, where the medium-high carbon steel is, for example, S53C; and a hardened layer 52 is formed on an outer peripheral surface from the shoulder portion 47a of the wheel mounting flange 4 to the cylindrical portion 47b, which is hardened by high-frequency induction quenching to a surface hardness of 50 to 64 HRC (shown by hatching in the drawing). The hardness of the upset portion 51 remains the same as a hardness obtained after forging. This increases the durability of the wheel hub 47 because the wheel hub 47 has sufficient mechanical strength to withstand a rotational bending load acting on the wheel mounting flange 4, and makes it possible to easily perform plastic deformation of the upset portion 51 and milling of the spur gear teeth 51a.

[0100] Here, in this embodiment, as in the above-described embodiment, since the end of the cylindrical portion 47b in the wheel hub 47 is formed as a hollow cylindrical part before upsetting, the annular groove 45 is formed on an outer peripheral surface of the cylindrical part, and the width of the annular groove 45 is set within a predetermined range, the cylindrical part can be easily deformed at the time of upsetting, the amount by which the inner ring 5 is compressed can be guaranteed, and deformation of the inner ring 5 due to oscillation upsetting can be prevented.

[0101] In addition, the width dimension of the inner ring 5 on the upsetting side (inner side), that is, the inner ring 5 of the two inner rings 49 and 5, is set larger than the width dimension of the outer-side inner ring 49. More specifically, the positions of the inner raceways 5a are the same, and the dimension Wi from the larger-diameter end of the inner raceway 5a to the larger end surface 5b is set longer than the dimension Wo from the larger-diameter end of the inner raceway 5a of the inner ring 49 to the larger end surface 5b. This makes it possible to prevent the deformation of the inner ring 5 on the upsetting side, that is, the deformation that would occur at the time of oscillation upsetting. Seventh embodiment

[0102] Fig. 15 is a longitudinal sectional view showing a seventh embodiment of the drive wheel bearing device; Fig. 16 is a longitudinal sectional view showing a storage unit of Fig. 15 shows; Fig. 17 is an enlarged view of the main section showing a sealing section of Fig. 15 shows; and Fig. 18 is an enlarged view of the main section showing a modified example of a gasket of Fig. 17. This embodiment differs from the previously described first embodiment ( Fig. 1) basically only in the presence or absence of the outer seal, and therefore components and parts that are identical or functionally equivalent to those in the first embodiment are designated by the same reference numerals, and their detailed description is omitted.

[0103] This drive wheel bearing assembly has a design referred to as the "third generation." It features a detachably integrated wheel hub 1, a double-row ball bearing 2, and a constant velocity joint 3.

[0104] As shown in an enlarged view of Fig. 16, the double-row ball bearing 2 includes an outer member 7, an inner member 8, and double-row rolling elements 9 and 9. On the other hand, double-row inner raceways 1a and 5a are formed in the inner member 8, which are arranged opposite to the outer raceways 7a and 7a of the outer member 7. Of the double-row inner raceways 1a and 5a, the inner raceway 1a (outer side) is formed integrally with the outer periphery of the wheel hub 1, and the inner raceway 5a (inner side) is formed integrally with the outer periphery of the inner ring 5. In this case, the inner member 8 refers to the wheel hub 1 and the inner ring 5.

[0105] Here in this embodiment, as in Fig. 15, a stepped portion 53 is formed in a shoulder portion 19 of an outer joint member 14. Furthermore, an outer seal 54 for sealing an engaging portion of the above-described spur gears 19a and 13a is mounted on the outer diameter of the inner ring 5. As shown in an enlarged view of Fig. 17, the outer seal 54 includes a metal core 55 consisting of a cylindrical part 55a pressed onto the outer diameter of the inner ring 5 and an inner diameter portion 55b extending radially inward from the cylindrical part 55a, and a sealing member 56 vulcanized to the metal core 55 or integrally bonded thereto by a similar bonding method.

[0106] The metal core 55 is made of a corrosion-resistant steel sheet, such as an austenitic stainless steel sheet (such as SUS304 in JIS), a ferritic stainless steel sheet (such as SUS430 in JIS), and a corrosion-resistant cold-rolled steel sheet (such as SPCC in JIS), which is pressed into a substantially L-shaped cross section. On the other hand, the sealing member 56 is made of synthetic rubber, such as nitrile rubber, and has a pair of lateral lips (axial lips) 56a and 56b extending laterally radially outward, and a grease lip 56c. Furthermore, the sealing lips 56a, 56b, and 56c make elastic contact with the stepped portion 53 of the shoulder portion 19.This makes it possible to prevent foreign matter such as rainwater and dust from entering the engaging portion of the spur gears 19a and 13a from the outside, and to absolutely prevent grease filled in the engaging portion from leaking out, thus preventing the spur gears 19a and 13a from corroding or wearing out. Furthermore, even if dimensional variations occur in the inner member 8 or the outer joint member 14 due to production or assembly errors, it is possible to achieve high sealing performance over a long period of time because the side lips 56a and 56b and the grease lip 56c have sufficient elasticity.

[0107] Fig. 18 is an enlarged view of the main portion showing a modified example of the above-described outer seal 54. Components and parts identical or functionally equivalent to those in the above-described embodiments are denoted by the same reference numerals; and their detailed descriptions are omitted.

[0108] This outer seal 57 includes a metal core 55 consisting of a cylindrical portion 55a pressed onto the outer diameter of the inner ring 5 and an inner diameter portion 55b extending radially inward from the cylindrical portion 55a, and a sealing member 58 integrally bonded to the metal core 55 by vulcanization or a similar bonding method. The sealing member 58 is made of synthetic rubber, such as nitrile rubber, and has an axial lip 58a with a circular arc-shaped tip. As a result, it is possible to prevent foreign matter such as rainwater and dust from entering the engaging portion of the spur gears 19a and 13a from the outside, and to absolutely prevent grease filled in the engaging portion from leaking out.Furthermore, the outer seal 57 can be simplified and compact, and since the abutting portion of the axial lip 58a is formed in a circular arc shape, even if the wheel hub 1 or the outer joint member 14 is deformed due to a large applied moment load, the outer seal 57 can accurately follow this deformation, thereby making it possible to obtain high sealing performance. Eighth embodiment

[0109] Fig. Fig. 19 is a longitudinal sectional view showing an eighth embodiment of the drive wheel support device. This embodiment has the same basic structure as the previously described second embodiment ( Fig. 4) and differs from the seventh embodiment ( Fig. 15) basically only in the structure of the double row ball bearing, and therefore components and parts that are identical or functionally equivalent to those in the embodiments described above are designated by the same reference numerals, and their detailed description is omitted.

[0110] A double row ball bearing 23 includes an outer element 7, an inner element 24, and double row rolling elements 9 and 9. The inner element 24 consists of a wheel hub 22 and an inner ring element 25 fitted into the wheel hub 22.

[0111] The inner ring member 25 is integrally formed with a cylindrical portion 27 extending axially from an inner raceway surface 5a. This cylindrical portion 27 is composed of a journal portion 27a that is press-fitted into a cylindrical portion 22a of the wheel hub 22, and a fitting portion 27b formed at the end of the journal portion 27a and disposed opposite an irregular portion 26 of the wheel hub 22. Furthermore, a spur gear 25a is formed on an inner end surface of the inner ring member 25. The inner ring member 25 is made of medium-high carbon steel containing 0.40 to 0.80 wt% carbon, the medium-high carbon steel being, for example, S53C, and is formed by cold forging or hot forging.

[0112] When cold forging is performed, the spur gear 25a is formed while forging is performed, or the spur gear 25a is formed after cold forging by cold plastic working such as orbital machining or by machining such as milling. When hot forging is performed, the spur gear 25a is formed after turning by cold plastic working such as orbital machining or by machining such as milling. The inner ring member 25 is hardened in a region from the inner raceway 5a to the journal portion 27a by high-frequency induction quenching to a surface hardness of 58 to 64 HRC. The fitting portion 27b retains the same hardness as a material hardness obtained after forging. Furthermore, the spur gear 25a may be formed after high-frequency induction quenching.

[0113] Here, the wheel hub 22 and the inner ring member 25 are plastically integrally coupled with an intended bearing preload caused by upsetting, wherein the fitting portion 27b is pressed and caulked into the irregular portion 26 of the wheel hub 22 by fitting the cylindrical part 27 of the inner ring member 25 into the wheel hub 22, and at the same time, the diameter of the fitting portion 27b is expanded by pressing a diameter-enlarging tool such as a mandrel into the fitting portion 27b. This eliminates the need to adjust the amount of preload by tightening it with a nut or the like, as is the case in the prior art. Therefore, it is possible to realize a reduction in weight and size, increase the strength and durability of the wheel hub 22, and maintain the amount of preload for a long time.

[0114] Furthermore, a fixing screw 21 is screwed into an internal thread 20a of a shaft portion 20, and spur gears 19a and 25a of a shoulder portion 19 of an outer joint member 14 and an inner end surface of the inner ring member 25 (with the spur gears 19a and 25a disposed opposite each other) are pressure-supported by the fixing screw 21 with a spacer 29 interposed therebetween, thereby detachably integrating the double-row ball bearing 23 and the constant velocity joint 3. The spacer 29 has a substantially L-shaped cross section and includes a flange portion 29a that abuts against the outer end surface of the wheel hub 22 and a cylindrical portion 29b that is slidably fitted onto the fixing screw 21. As a result, it is possible to easily center the outer joint element 14 and the inner element 24 by means of the spacer 29.This simplifies the disassembly and assembly processes of the fixture. Furthermore, the spur gears 19a and 25a can engage without circumferential and axial play.

[0115] Furthermore, as in the case of the above-described embodiment, an outer seal 54 for sealing an engaging portion of the above-described spur gears 19a and 25a is mounted on the outer diameter of the inner ring 5, and seal lips 56a, 56b, and 56c make elastic contact with the stepped portion 53 of the shoulder portion 19. This makes it possible to prevent foreign matter such as rainwater and dust from entering the engaging portion of the spur gears 19a and 25a from the outside, and to absolutely prevent grease filled in the engaging portion from leaking out, thus preventing the spur gears 19a and 25a from corroding or wearing out.Furthermore, even if dimensional variations occur in the inner member 24 or the outer joint member 14 due to production or assembly errors, it is possible to achieve high sealing performance over a long period of time because the side lips 56a and 56b and the grease lip 56c have sufficient elasticity. Ninth embodiment

[0116] Fig. Fig. 20 is a longitudinal sectional view showing a ninth embodiment of the drive wheel support device. This embodiment has the same basic structure as the previously described third embodiment ( Fig. 6) and differs from the seventh embodiment ( Fig. 15) basically only in the structure of the double row ball bearing, and therefore components and parts that are identical or functionally equivalent to those in the above-described embodiments are designated by the same reference numerals; and their detailed description is omitted.

[0117] A double-row ball bearing 31 has an outer element 7, an inner element 32, and double-row rolling elements 9 and 9. The inner element 32 consists of a wheel hub 30 and an inner ring element 33 that is press-fitted into the wheel hub 30 and secured thereto by a predetermined interference fit. In the inner ring element 33, the inner ring element 33 and the wheel hub 30 are plastically coupled integrally with a predetermined bearing preload generated by a swaged portion 34a formed by plastically deforming the end of the cylindrical part 34 radially outward.

[0118] Furthermore, as in the case of the previously described embodiments, the inner ring member 33 including the spur gear teeth 25a is formed by cold forging or hot forging; however, thermal annealing (high-temperature tempering after quenching) may also be performed on the inner ring member 33 after it is forged. Through thermal annealing, it is possible to ensure low hardness and high impact toughness.

[0119] Here, a fastening screw 21 is screwed into an internal thread 20a of the shaft portion 20, and spur gears 19a and 25a of an outer joint element 14 and the inner ring element 33 (wherein the spur gears 19a and 25a are arranged opposite each other) are supported by pressure by the fastening screw 21 - with a spacer 35 arranged therebetween - whereby the double-row ball bearing 31 and the constant velocity joint 3 are detachably integrated.

[0120] In this embodiment, the structure in which the inner ring member 33 is press-fitted into and fixed to the cylindrical portion 22a of the wheel hub 30 is taken as an example; however, the present invention is not limited to this structure. Although not shown in the drawing, the above-mentioned two members may be fixed to each other by means of a serration formed on the inner circumference of the wheel hub and a serration that engages the former serration and is formed in the cylindrical part of the inner ring member.

[0121] Furthermore, although not shown in the drawing, the spacer described in the eighth and ninth embodiments, which has a substantially L-shaped cross section and is used with the fastening bolt, can also be used in the seventh embodiment. That is, by omitting the smaller diameter portion on the inner diameter of the wheel hub through which the fastening bolt is inserted, providing the inner diameter portion of the wheel hub with a cylindrical shape, allowing the flange portion of the spacer to abut against the outer end surface of the wheel hub, and using the cylindrical inner diameter portion of the wheel hub to guide the cylindrical part of the spacer that is inserted onto the fastening bolt, it is possible to easily center the outer joint member and the inner member. This simplifies the disassembly and assembly procedures of the device.In addition, the spur gears can mesh without circumferential and axial play. Furthermore, by eliminating the smaller diameter section, it is possible to reduce the weight of the product.

[0122] Furthermore, as in the case of the above-described embodiment, an outer seal 54 for sealing an engaging portion of the above-described spur gears 19a and 25a is mounted on the outer diameter of the inner ring 33, and seal lips 56a, 56b, and 56c make elastic contact with a stepped portion 53 of a shoulder portion 19. This makes it possible to prevent foreign matter such as rainwater and dust from entering the engaging portion of the spur gears 19a and 25a from the outside, and to absolutely prevent grease filled in the engaging portion from leaking out, thus preventing the spur gears 19a and 25a from corroding or wearing out.Furthermore, even if dimensional variations occur in the inner member 32 or the outer joint member 14 due to production or assembly errors, it is possible to achieve high sealing performance over a long period of time because the side lips 56a and 56b and the grease lip 56c have sufficient elasticity. Tenth embodiment

[0123] Fig. 21 is a longitudinal sectional view showing a tenth embodiment of the drive wheel bearing device according to the present invention; Fig. 22 is a longitudinal sectional view showing a constant velocity joint of Fig. 21 shows; Fig. 23 is an enlarged view of the main section showing an outer seal section of Fig. 21 shows; Fig. 24 is an enlarged view of the main section showing a modified example of an outer seal of Fig. 23 shows; Fig. 25 is an enlarged view of the main section showing another modified example of the outer seal of Fig. 23 shows; and Fig. Fig. 26 is an enlarged view of the main portion showing another modified example. This embodiment differs from the previously described seventh embodiment ( Fig. 15) basically only in the structure of the outer seal, and therefore components and parts that are identical or functionally equivalent to those in the embodiments described above are designated by the same reference numerals, and their detailed description is omitted.

[0124] This drive wheel bearing device has a structure referred to as the "third generation." It detachably integrates a wheel hub 1, a double-row ball bearing 2, and a constant velocity joint 3. The double-row ball bearing 2 includes an outer element 7, an inner element 8, and double-row rolling elements 9 and 9.

[0125] Here in this embodiment, an outer seal 59 for sealing an engagement portion of the above-described spur gears 19a and 13a is mounted on a shoulder portion 19 of an outer joint member 14. As shown in Fig. 22, the outer seal 59 consists of a cylindrical metal core 60 which is pressed onto the outer diameter of the shoulder portion 19, and a sealing element 61 which is vulcanized to the metal core 60 or integrally connected thereto by means of a similar bonding process.

[0126] The metal core 60 is made of a corrosion-resistant steel sheet, such as an austenitic stainless steel sheet (such as SUS304 in JIS), a ferritic stainless steel sheet (such as SUS430 in JIS), and a corrosion-resistant cold-rolled steel sheet (such as SPCC in JIS), which is pressed into a substantially L-shaped cross section. On the other hand, the sealing member 61 is made of synthetic rubber, such as ACM and NBR, and has a pair of lateral lips (axial lips) 61a and 61b that radially bifurcate laterally. In addition, as shown in an enlarged view of Fig. 23, the sealing lips 61a and 61b make elastic contact with a larger end surface 5b of an inner ring 5.

[0127] This makes it possible to prevent foreign matter such as rainwater and dust from entering the engaging portion of the spur gears 19a and 13a from the outside, and to absolutely prevent grease filled in the engaging portion from leaking out, thus preventing the spur gears 19a and 13a from corroding or wearing out. Furthermore, even if dimensional variations occur in the inner member 8 or the outer joint member 14 due to production or assembly errors, it is possible to achieve high sealing performance for a long time because the side lips 61a and 61b have sufficient elasticity and make elastic contact with the larger end surface 5b of the inner ring 5, and a predetermined surface roughness is formed on the larger end surface 5b by grinding.In addition to the rubbers described above, rubbers having excellent heat resistance, such as HNBR (hydrogenated acrylonitrile butadiene rubber), EPDM (ethylene propylene rubber), FKM (fluorocarbon rubber), EPM (ethylene propylene rubber), and silicone rubber, can also be used as the sealing member 61.

[0128] Fig. 24 is an enlarged view of the main portion showing a modified example of the above-described outer seal 59. Note that components and parts identical or functionally equivalent to those in the above-described embodiments are denoted by the same reference numerals; and detailed descriptions thereof will be omitted.

[0129] This outer seal 62 includes a metal core 63 formed by a first cylindrical portion 63a pressed onto the outer diameter of the shoulder portion 19 of the outer joint member 14, a tapered portion 63b extending radially outward laterally from the first cylindrical portion 63a, and a second cylindrical portion 63c extending axially from the tapered portion 63b. A sealing member 64 is vulcanized to the metal core 63 or integrally bonded thereto by a similar bonding method. The sealing member 64 is made of synthetic rubber, such as ACM or NBR, and has a pair of bifurcated radial lips 64a and 64b. The pair of radial lips 64a and 64b make elastic contact with the outer diameter of the inner ring 5.This makes it possible to prevent foreign matter such as rainwater and dust from entering the engagement portion of the spur gears 19a and 13a from the outside, and to absolutely prevent grease filled in the engagement portion from leaking out. Furthermore, since the outer seal 62 has the pair of radial lips 64a and 64b, even if the wheel hub 1 or the outer joint member 14 is deformed due to a strong moment load, the outer seal 62 can accurately follow this deformation, making it possible to maintain high sealing performance.

[0130] Fig. 25 is an enlarged view of the main section showing another modified example of the above-described outer seal. Note that components and parts identical or functionally equivalent to those in the above-described embodiment are denoted by the same reference numerals; their detailed description will be omitted.

[0131] This outer seal 65 consists of a cylindrical metal core 66 pressed onto the outer diameter of the shoulder portion 19 of the outer joint member 14, and a sealing member 67 vulcanized to the metal core 66 or integrally bonded thereto by a similar bonding method. The sealing member 67 is made of synthetic rubber, such as ACM or NBR, and has an axial lip 67a with a circular arc-shaped tip. The axial lip 67a makes elastic contact with the larger end surface 5b of the inner ring 5. This makes it possible to prevent foreign matter, such as rainwater and dust, from entering the engaging portion of the spur gears 19a and 13a from the outside, and to absolutely prevent the grease filled in the engaging portion from leaking out.Furthermore, even if the wheel hub 1 or the outer joint member 14 is deformed due to a large applied moment load, the outer seal 65 can accurately follow this deformation because the outer seal 65 is simplified and the abutting portion of the axial lip 67a is formed in a circular arc shape, thereby making it possible to obtain high sealing performance.

[0132] Fig. 26 is an enlarged view of the main portion showing another modified example of the above-described outer seal. Note that components and parts identical or functionally equivalent to those in the above-described embodiment are denoted by the same reference numerals; detailed descriptions thereof will be omitted.

[0133] This outer seal 68 consists of a cylindrical metal core 69 pressed onto the outer diameter of the shoulder portion 19 of the outer joint member 14, and a sealing member 70 vulcanized to the metal core 69 or integrally bonded thereto by a similar bonding method. The sealing member 70 is made of synthetic rubber, such as ACM or NBR, and has a lateral lip 70a extending laterally radially outward and a radial lip 70b extending laterally radially inward. The lateral lip 70a makes elastic contact with the side surface of an upright portion 74b of a scraper ring 74 forming an inside seal 12, and the radial lip 70b makes elastic contact with the outer diameter of the inner ring 5.

[0134] Here, the inside seal 12 is formed as a so-called packing seal provided with an annular seal plate 73 and a scraper ring 74 having a substantially L-shaped cross section, wherein the seal plate 73 is formed of a metal core 71 fitted into the end of the outer member 7, the metal core 71 having a substantially L-shaped cross section, and a seal member 72 vulcanized to the metal core 71, wherein the scraper ring 74 is formed of a cylindrical part 74a pressed onto the outer diameter of the inner ring 5 and an upright portion 74b extending radially outward from the cylindrical part 74a.

[0135] The sealing member 72 is made of synthetic rubber such as NBR and has a lateral lip 72a making sliding contact with the upright portion 74b of the scraper ring 74 while maintaining a predetermined axial interference fit therebetween, and a grease lip 72b and an intermediate lip 72c formed in a fork shape, the grease lip 72b and the intermediate lip 72c making sliding contact with the cylindrical portion 74a while maintaining a predetermined axial interference fit therebetween.

[0136] With such a structure, it is possible to prevent foreign matter such as rainwater and dust from entering the engagement portion of the spur gears 19a and 13a from the outside, and to absolutely prevent grease filled in the engagement portion from leaking out. Furthermore, because the outer seal 68 has the side lip 70a that contacts the wiper ring 74, it is possible to prevent foreign matter such as rainwater and dust from entering the bearing through a fitting portion between the wiper ring 74 and the inner ring 5, thereby increasing the durability of the bearing. Eleventh embodiment

[0137] Fig. Fig. 27 is a longitudinal sectional view showing an eleventh embodiment of the drive wheel bearing device. This embodiment has the same basic structure as the previously described second embodiment ( Fig. 4) and differs from the tenth embodiment ( Fig. 21) basically only in the structure of the double row ball bearing, and therefore components and parts that are identical or functionally equivalent to those in the above-described embodiments are designated by the same reference numerals; and their detailed description is omitted.

[0138] A double row ball bearing 23 includes an outer element 7, an inner element 24, and double row rolling elements 9 and 9. The inner element 24 consists of a wheel hub 22 and an inner ring element 25 fitted into the wheel hub 22.

[0139] In this embodiment, an outer seal 59 is mounted on a shoulder portion 19 of an outer joint member 14, and side lips 61a and 61b of the outer seal 59 make elastic contact with a step portion 28 of the inner ring member 25, thereby sealing an engaging portion of spur gears 19a and 25a.

[0140] This makes it possible to prevent foreign substances such as rainwater and dust from entering the engagement portion of the spur gears 19a and 25a from the outside, and to absolutely prevent grease filled in the engagement portion from leaking out, thus preventing the spur gears 19a and 25a from corroding or wearing out. Twelfth embodiment

[0141] Fig. Fig. 28 is a longitudinal sectional view showing a twelfth embodiment of the drive wheel bearing device. This embodiment has the same basic structure as the previously described third embodiment ( Fig. 6) and differs from the tenth embodiment ( Fig. 21) basically only in the structure of the double row ball bearing, and therefore components and parts that are identical or functionally equivalent to those in the previously described embodiments are designated by the same reference numerals; and their detailed description is omitted.

[0142] A double row ball bearing 31 includes an outer element 7, an inner element 32, and double row rolling elements 9 and 9. The inner element 32 consists of a wheel hub 30 and an inner ring element 33 fitted into the wheel hub 30 and secured thereto by a predetermined interference fit.

[0143] Furthermore, as in the case of the previously described embodiments, the inner ring member 33 including the spur gear teeth 25a is formed by cold forging or hot forging; however, thermal annealing (high-temperature tempering after quenching) may also be performed on the inner ring member 33 after it is forged. Through thermal annealing, it is possible to ensure low hardness and high impact toughness.

[0144] In this embodiment, an outer seal 59 is mounted on a shoulder portion 19 of an outer joint member 14, and side lips 61a and 61b of the outer seal 59 make elastic contact with a step portion 28 of the inner ring member 33, thereby sealing an engaging portion of the spur gears 19a and 25a.

[0145] This makes it possible to prevent foreign substances such as rainwater and dust from entering the engagement portion of the spur gears 19a and 25a from the outside, and to absolutely prevent grease filled in the engagement portion from leaking out, thus preventing the spur gears 19a and 25a from corroding or wearing out. INDUSTRIAL APPLICABILITY

[0146] A drive wheel bearing device according to the present invention can be applied to a drive wheel bearing device in which a double row ball bearing is detachably integrated with a wheel hub and a constant velocity joint. EXPLANATIONS OF LETTERS OR NUMBERS

[0146] 1, 22, 30, 41, 47 wheel hub 1a, 5a inner running surface 1b, 22a, 47b cylindrical section 1c Section with smaller diameter 2, 23, 31, 36, 42, 48 double row ball bearing 3 constant velocity joint 4 Wheel mounting flange 4a inside base of the wheel mounting flange 5, 49 inner ring 5b larger end surface of the inner ring 5c chamfered section of the inner ring 7 outer element 7a outer running surface 7b Body mounting flange 8, 24, 32, 37, 43 inner element 9 Rolling element 10 cages 11, 50 external seal 12 inside seal 13, 34a, 51 compressed section 13a, 19a, 25a, 51a spur gearing 14 outer joint element 15 Joint inner ring 15a, 18a rut 16 cage 17 Torque transmission ball 18 Mouth section 19, 47a shoulder section 20 wave section 20a internal thread 21, 40 fixing screw 25, 33, 38 inner ring element 26 irregular section 27, 29b, 34, 35b, 39, 44, 55a, 74a cylindrical part 27a Tenon section 27b Fitting section 28 step section 29, 35 spacer 29a, 35a flange section 39a Guide Section 44a, 44b chamfered section of the cylindrical part 45, 45' ring groove 45a, 45b circular arc area 46, 52 hardened layer 53 stepped section 54, 57, 59, 62, 65, 68 outer seal 55, 60, 63, 66, 69, 71 metal core 55b inner diameter section 56, 58, 61, 64, 67, 70, 72 sealing element 56a, 56b, 61a, 61b, 70a, 72° lateral lip 56c, 72b lip 58a, 67a axial lip 63a first cylindrical part 63b oblique section 63c second cylindrical part 64a, 64b, 70b radial lip 72c Interdental lip 73 Sealing plate 74 scraper ring 74b upright section 101 double row ball bearing 102 Constant velocity joint 103 outer element 103a outer running surface 103b Body mounting flange 104 Wheel hub 104a, 105a inner running surface 104b Wheel mounting flange 104c cylindrical section 105 inner ring 106 inner element 107 Cage 108 ball 109 compressed section 109a, 117a Spur gearing 110, 111 Seal 112 outer joint element 113 Joint inner ring 114 Cage 115 Torque transmission ball 116 Mouth section 117 shoulder section 118 wave section 118a internal thread 119 Fixing screw

Claims

[1] Drive wheel bearing device with a double-row ball bearing (2) and a constant velocity joint (3) which are detachably integrated, wherein in this device the double-row ball bearing (2) contains: an outer member (7) having a body mounting flange (7b) to be mounted on a vehicle body, the body mounting flange (7b) being integrally formed on the outer circumference and being provided with an integrally formed double-row outer raceway (7a) on the inner circumference; an inner member (8) formed from a wheel hub (1) and a cylindrical inner ring member, the wheel hub (1) having a wheel mounting flange (4) for mounting a wheel, the wheel mounting flange (4) being integrally formed at one end and having on its outer periphery an inner raceway surface (1a) disposed opposite the double-row outer raceway surface (7a) and a cylindrical portion (1b) extending axially from the inner raceway surface (1a), the inner ring member being press-fitted onto the wheel hub (1) and having on its outer periphery the other inner raceway surface (5a) disposed opposite the double-row outer raceway surface (7a); and a double-row roller element (9) which is freely rollable and is accommodated between the running surfaces (1a, 5a, 7a) of the inner element (8) and the outer element (7); and the constant velocity joint (3) comprises an outer joint element (14) with a cup-shaped mouth portion (18), a shoulder portion (19) forming the bottom of the mouth portion (18), and a cylindrical shaft portion (20) extending axially from the shoulder portion (19), wherein the shaft portion (20) is provided with an internal thread (20a), and wherein the mouth portion (18), the shoulder portion (19) and the shaft portion (20) are integrally formed in the outer joint element (14), wherein spur gear teeth (13a, 19a) are formed on the respective end surfaces of the shoulder portion (19) of the outer joint element (14) and the inner ring element, and wherein the spur gear teeth (13a, 19a) are supported by pressure by a fastening screw (21) which bears against an outer end surface of the wheel hub (1) and is screwed to the internal thread (20a) of the shaft section (20), and wherein the double-row ball bearing (2) and the constant velocity joint (3) are coupled to each other in such a way that the double-row ball bearing (2) and the constant velocity joint (3) can transmit torque and are axially separable, wherein the wheel hub (1) and the inner ring element are plastically integrally coupled, and wherein on the surfaces of the spur gear teeth (13a, 19a) as a result of a Surface modification, a residual compression stress acts, wherein an outer seal (68) is mounted on the outer diameter of the shoulder portion (19) of the outer joint element (14), the outer seal (68) includes a cylindrical metal core (69) pressed onto the outer diameter of the shoulder portion (19), and a sealing element (70) vulcanized to the metal core (69) or integrally bonded thereto by means of a similar bonding process, and a lip (70a, 70b) of the sealing element (70) is brought into elastic contact with the inner element (8) or an inside seal (12) of the seal, thereby sealing the engagement portion of the spur gears (13a, 19a), and wherein the inner seal (12) is designed as a packing seal provided with an annular sealing plate (73) and a scraper ring (74) with a substantially L-shaped cross-section, the sealing plate (73) being formed from a metal core (71) fitted into the end of the outer element (7), the metal core (71) having a substantially L-shaped cross-section, and a sealing element (72) vulcanized to the metal core (71), the scraper ring (74) being formed from a cylindrical part (74a) pressed onto the outer diameter of the inner ring (5) and an upright portion (74b) extending radially outward from the cylindrical part (74a), the sealing element (70) of the outer seal (68) having a lateral lip (70a) extending laterally radially outward and a radial lip (70b) extending laterally radially inward, has,the lateral lip (70a) is brought into elastic contact with a side surface of the upright portion (74b) of the scraper ring (74), and the radial lip (70b) is brought into elastic contact with the outer diameter of the inner ring (5). [2] A drive wheel bearing device according to claim 1, wherein the spur gear teeth (13a) of the inner ring member are formed while the inner ring member is formed by cold forging. [3] A drive wheel bearing device according to claim 1 or 2, wherein a step portion is formed at one end of the inner ring member, and the spur gear (13a) is formed on a protruding end surface. [4] A drive wheel bearing device according to any one of claims 1 to 3, wherein a hardened irregular portion is formed on the inner circumference of the wheel hub (1), and the wheel hub (1) and the inner ring member are plastically integrally coupled with a predetermined bearing preload applied by inserting a cylindrical part of the inner ring member into the irregular portion and pressing the cylindrical part into the irregular portion by expanding the diameter of the cylindrical part. [5] A drive wheel bearing device according to any one of claims 1 to 3, wherein a cylindrical part of the inner ring member is fitted into the wheel hub (1), and the wheel hub (1) and the inner ring member are plastically integrally coupled with a predetermined bearing preload generated by means of a swaged portion (13) formed by plastically deforming one end of the cylindrical part radially outward. [6] A drive wheel bearing device according to any one of claims 1 to 5, wherein the fastening screw (21) is screwed to the internal thread (20a) of the shaft portion (20) with a spacer disposed therebetween, and the spacer has a substantially L-shaped cross section and includes a flange portion abutting against an end surface of the wheel hub (1) and a cylindrical part slidably guided onto the fastening screw (21). [7] A drive wheel bearing device according to any one of claims 1 to 3 and 5, wherein a radially inwardly projecting guide portion is formed on the inner circumference of a cylindrical part of the inner ring member, and the fastening screw (21) is pushed through the guide portion and screwed to the internal thread (20a) of the shaft portion (20). [8] Drive wheel bearing device according to one of claims 1 to 7, wherein the surface hardness of the spur gear teeth (13a, 19a) is set to at least 300 Hv. [9] Drive wheel bearing device according to one of claims 1 to 8, wherein the surface of the spur gear teeth (13a, 19a) is subjected to shot peening or WPC as surface modification. [10] Drive wheel bearing device according to one of claims 1 to 9, wherein hardening is carried out by laser hardening on the surface of the spur gear teeth (13a, 19a). [11] A drive wheel bearing device according to any one of claims 8 to 10, wherein one end of the cylindrical portion is formed as a hollow cylindrical part before upsetting, an annular groove having a predetermined depth is formed on an outer peripheral surface of the cylindrical part, extending from a position corresponding to a larger diameter end of the inner raceway surface of the inner ring (5) to a position extending beyond a larger end surface (5b) of the inner ring (5), and one end of the cylindrical part is plastically deformed so that a part of the annular groove is brought into direct contact with a chamfered portion of the inner ring (5) and the remaining part has no contact with the inner ring (5) and a gap is left. [12] A drive wheel bearing device according to claim 11, wherein the annular groove is formed in a region ranging from a position corresponding to the larger diameter end of the inner raceway surface of the inner ring (5) to the chamfered portion on the larger end surface (5b) side, the region extending slightly beyond the larger end surface (5b). [13] The drive wheel bearing device according to claim 11 or 12, wherein the bottom of the annular groove is formed as a tapered surface having a diameter that gradually becomes smaller toward the tip of the cylindrical part, and the inclination angle of the tapered surface is set to a maximum of 15°. [14] The drive wheel bearing device according to any one of claims 11 to 13, wherein circular arc surfaces having radii of curvature Ri and Ro are formed on the sides of the annular groove, and the radius of curvature Ri of the inner side circular arc surface of the circular arc surfaces is smaller than the radius of curvature Ro of the outer side circular arc surface (Ri ≤ Ro) and is set within a range of R1 to 10. [15] A drive wheel bearing device according to any one of claims 11 to 14, wherein a chamfered portion having a circular arc surface having a radius of curvature is formed at an inner diameter end on the larger end surface (5b) side of the inner ring (5), and the radius of curvature of the chamfered portion is set to a range of R1.0 to 2.

5. [16] The drive wheel bearing device according to any one of claims 11 to 15, wherein the depth of the annular groove is set to a depth of 0.5 to 2.0 mm. [17] A drive wheel bearing device according to any one of claims 11 to 16, wherein a hardened layer is formed in the cylindrical portion of the wheel hub (1) by high frequency induction quenching to a surface hardness of 50 to 64 HRC, and an inside edge of the hardened layer is arranged within a range from an outside starting point in the annular groove to 0 to 4.0 mm on the outside and on the inside to 0 to 3.0 mm in a range of an outside circular arc surface of the annular groove. [18] A drive wheel bearing device according to any one of claims 11 to 17, wherein two inner rings (5) are press-fitted onto the cylindrical portion of the wheel hub (1), the positions of the inner raceways (5a) of the two inner rings (5) are the same, and the length from the larger diameter end of the inner raceway (5a) of the inner ring (5) on the upsetting side to the larger end surface (5b) is greater than the length from the larger diameter end of the inner raceway of the other inner ring to the larger end surface (5b). [19] A drive wheel bearing device according to any one of claims 1 to 18, wherein a seal is mounted on the outer diameter of the inner ring (5) or the inner ring member, the seal includes a metal core pressed onto the outer diameter of the inner ring or the inner ring member and a sealing member made of synthetic rubber, the sealing member is vulcanized to the metal core or integrally bonded thereto by a similar bonding method and has an axial lip, and the axial lip elastically contacts the shoulder portion of the outer joint member and thereby seals an engaging portion of the spur gears. [20] A drive wheel bearing device according to claim 19, wherein the sealing member has a lateral lip extending laterally radially outward, a stepped portion is formed in the shoulder portion (19) of the outer joint member (14), and the lateral lip is brought into elastic contact with the stepped portion. [21] The drive wheel bearing device according to claim 19, wherein the tip of the axial lip is formed into a circular arc shape. [22] Drive wheel bearing device according to one of claims 19 to 21, wherein the sealing element has a grease lip and the engagement portion of the spur gears (13a, 19a) is filled with grease. [23] A drive wheel bearing device according to claim 1, wherein the sealing member has dividing side lips extending radially laterally, and the side lips are brought into elastic contact with the larger end surface (5b) of the inner ring (5). [24] A drive wheel bearing device according to claim 1, wherein the sealing member has an axial lip with a circular arc-shaped tip, and the axial lip is brought into elastic contact with the larger end surface (5b) of the inner ring (5). [25] A drive wheel bearing device according to claim 1, wherein the sealing member has a pair of dividing radial lips, and the radial lips are brought into elastic contact with the outer diameter of the inner ring (5).

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