JP2013032093A - Bearing device for wheel and preload management method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bearing device for a wheel and a preload management method thereof, capable of stably managing a preload by restraining a variation, by preventing generation of excessive stress in a gear member and enhancing strength of the gear member.SOLUTION: An inner ring 7 is fixed in the axial direction by a caulking part 10 formed by plastically deforming an end part of a small diameter step part 4b of a hub wheel 4 outward in the radial direction, in a state of applying a predetermined bearing preload via the ring-shaped gear member 18, the gear member 18 is made of a steel material having a carbon quantity of medium carbon steel or less, hardening processing is performed up to a core part by immersion quenching, the outer periphery is formed with a gear part 18a, the inner periphery is formed with a spline part 18b meshing with a hub spline part formed on an outer peripheral surface of the small diameter step part 4b of the hub wheel 4, and surface hardness of the gear member 18 has a hardness difference of at least 130 HV from the hub wheel 4.

Description

  The present invention relates to a wheel bearing device for rotatably supporting a wheel of an automobile or the like, and more particularly to a wheel bearing device having a clutch function for switching a wheel between driving and non-driving and a preload management method thereof.

  In some four-wheel drive vehicles, a front wheel or a rear wheel can be selectively switched to a driven wheel by a clutch function provided in a wheel bearing device. A conventional example of such a wheel bearing device with a clutch function is shown in FIG. This wheel bearing device includes an outer member 50 attached to the vehicle body side, and an inner member having an inner rolling surface 55a facing the double-row outer rolling surfaces 50a, 50a on the inner periphery of the outer member 50. 51 and double-row tapered rollers 52, 52 interposed between the opposing rolling surfaces 50a, 55a. The inner member 51 includes a hub ring 54 having a wheel mounting flange 53 and two inner rings 55 and 56 that are fitted to the outer periphery of the hub ring 54 in the axial direction. Each row has inner rolling surfaces 55a, 55a in each row. A shaft portion of an outer joint member (not shown) of a constant velocity universal joint serving as a drive shaft is rotatably supported on the inner circumference of the hub wheel 54 via bearings 57 and 58.

  Of the two inner rings 55, 56 that are press-fitted into the outer periphery of the hub ring 54, the inner ring 56 on the inner end side is formed with a gear part 56a on the outer periphery, and a spline-like part 56b is formed on the inner periphery of the end part. Yes. A spline-shaped portion 54a is formed on the outer periphery of the inner end portion of the hub wheel 54, and the spline-shaped portion 56b of the inner ring 56 is engaged with the spline-shaped portion 54a. The inner end portion of the hub ring 54 is a flange-shaped caulking portion 54 b that presses the large end surface of the inner ring 56, and the inner ring 56 is fixed to the hub wheel 54 in the axial direction by the caulking portion 54 b.

  A ring-shaped slide gear 60 that meshes with a gear portion 59 formed on the outer joint member is selectively meshed with the gear portion 56a of the inner ring 56 by sliding in the axial direction. A driving force is transmitted from the outer joint member to the wheels via the inner ring 56 and the hub ring 54 in a state where the gear portion 56 a of the inner ring 56 and the gear portion 59 of the outer joint member are connected via the slide gear 60. . That is, at this time, the wheel supported by the hub wheel 54 becomes a drive wheel. In a state where the slide gear 60 is not meshed with the gear portion 56a of the inner ring 56, the driving force is not transmitted to the wheel, and the wheel supported by the hub wheel 54 at this time becomes a driven wheel.

  In such a configuration, the outer peripheral portion of the inner ring 56 is formed with the gear portion 56a that can be engaged with the slide gear 60 that meshes with the gear portion 59 of the outer joint member, so that the slide gear 60 is engaged with the gear portion 56a. A clutch function can be provided depending on the presence or absence. Further, since the gear portion 56a is formed integrally with the inner ring 56, fretting wear does not occur. For this reason, it is possible to sufficiently secure an axial force for clamping the inner ring 56 to the hub ring 54 to prevent bearing play, and to prevent a stick-slip sound from the inner ring 56 at the time of sudden start (for example, Patent Document 1). reference.).

JP 2005-138653 A

  However, in this conventional wheel bearing device, the spline-like portion 56b is formed on the inner periphery of the end portion of the inner ring 56, and the spline-like portion 54a meshing with the spline-like portion 56b is formed on the hub wheel 54. Therefore, when the inner end portion of the hub wheel 54 is plastically deformed to form the caulking portion 54b, it is difficult to form the caulking portion 54b radially outward along the spline-like portion 56b, and caulking defects such as microcracks occur. There is a risk that cracks starting from the gear portion 56a on the outer periphery of the end of the inner ring 56 may easily occur.

  Here, if the tooth surface of the gear portion 56a is too hard, it causes cracks and cracks during caulking, but the hardness required for the gear portion 56a itself is not satisfied even if it is too soft.

  The present invention has been made in view of such circumstances, and by providing a gear portion that is soft to some extent that satisfies both problems, it is possible to prevent excessive stress from being generated in the gear member, and It is an object of the present invention to provide a wheel bearing device and a preload management method thereof that can increase strength and suppress variation and perform stable preload management.

  In order to achieve such an object, the invention according to claim 1 of the present invention has a vehicle body mounting flange integrally attached to the knuckle constituting the suspension device on the outer periphery, and double row outer rolling on the inner periphery. A hub wheel having an outer member integrally formed with a surface, a wheel mounting flange for mounting a wheel at one end, and a cylindrical small-diameter step portion extending in the axial direction on the outer periphery; and An inner member having at least one inner ring press-fitted into a small-diameter step portion of the hub wheel through a predetermined shimoshiro and having a double-row inner rolling surface facing the double-row outer rolling surface on the outer periphery. And a double row rolling element that is rotatably accommodated between the rolling surfaces of the inner member and the outer member via a cage, wherein the hub wheel has a small diameter. A crimped part formed by plastically deforming the end of the step part radially outward. The inner ring is fixed in the axial direction with a predetermined bearing preload applied via a ring-shaped gear member, and the gear member is made of a steel material having a carbon content equal to or less than medium carbon steel. The core is hardened, and a spline part is formed on the outer periphery and a gear part on the outer periphery and a hub spline part formed on the outer peripheral surface of the small diameter step part of the hub wheel. Is set.

  In this way, the outer member integrally having the vehicle body mounting flange on the outer periphery, the outer member in which the double row outer rolling surface is integrally formed on the inner periphery, and the wheel mounting flange on the one end are integrated, and on the outer periphery. A hub wheel formed with a cylindrical small-diameter step portion extending in the axial direction, and at least one inner ring press-fitted into the small-diameter step portion of the hub ring through a predetermined shimoshiro, and outer rows of double rows on the outer periphery An inner member in which a double row inner rolling surface facing the surface is formed, and a double row of the inner member and the outer member that are accommodated so as to be able to roll through a retainer between the rolling surfaces of the inner member and the outer member. In a wheel bearing device including a rolling element, an inner ring is connected to a predetermined bearing via a ring-shaped gear member by a caulking portion formed by plastically deforming an end portion of a small-diameter step portion of a hub wheel radially outward. It is fixed in the axial direction with preload applied, and the gear member has a carbon content below medium carbon steel. These gear parts are made of steel and hardened to the core part by quenching to form a gear part on the outer periphery and a spline part that meshes with the hub spline part formed on the outer peripheral surface of the small diameter step part of the hub wheel on the inner periphery. And the spline part are set to the same hardness, so that excessive stress can be prevented from occurring in the gear member in the caulking process, and deformation and microcracks can be prevented, and the gear member can be caulked. Therefore, the amount of elastic deformation can be measured with high accuracy, high accuracy, and stable preload management can be performed while suppressing variation.

  Preferably, as in the invention described in claim 2, if the surface hardness of the gear member has a hardness difference of at least 130 HV from the hub wheel, not only the gear portion and spline portion of the gear member but also the gear. As a whole, the desired strength can be ensured, and when forming the caulking portion, the end of the small diameter step of the hub wheel can be plastically deformed radially outward, and the caulking portion can be microcracked. It is possible to prevent a caulking defect from occurring.

  Moreover, if the gear member contains Cr 0.09 to 0.12 wt% and the surface hardness is set in a range of 392 to 600 HV as in the invention according to claim 3, the strength of the gear member is high. Thus, it is possible to prevent deformation and microcracks from occurring when excessive stress is generated in the caulking process.

  Further, as in the invention according to claim 4, if the gear member is formed of a steel material made of carbon of 0.15 to 0.45 wt%, a gear portion having an appropriate hardness can be obtained. In addition to the spline portion, desired strength can be ensured.

  Moreover, if the gear member is made of chromium molybdenum steel containing 0.15 to 0.3 wt% of Mo as in the invention described in claim 5, brittleness can be suppressed, and caulking is performed. It is possible to reliably prevent occurrence of minute cracks at the time and to ensure strength when a driving force is applied.

  Further, as in the invention described in claim 6, if the tooth bottom of the gear portion of the gear member is formed in an arc shape having a predetermined radius of curvature, the force during caulking is dispersed, and the tooth bottom is The crack which generate | occur | produces can be prevented.

  Further, as in the invention described in claim 7, the hub wheel is formed of medium-high carbon steel containing carbon of 0.40 to 0.80 wt%, and is formed from the base portion on the inner side of the wheel mounting flange to the small diameter step portion. If a predetermined hardened layer is formed in the range of 58 to 64 HRC by induction hardening and the caulking portion is an unquenched portion with the surface hardness after forging, caulking is performed. This makes it easy to prevent the occurrence of microcracks during processing, and has sufficient mechanical strength against the rotational bending load applied to the wheel mounting flange, thereby improving the durability of the hub wheel.

  According to the eighth aspect of the present invention, the method invention according to claim 8 integrally has a vehicle body mounting flange to be attached to the knuckle constituting the suspension device on the outer periphery, and a double row outer rolling surface is integrated on the inner periphery. An outer member formed integrally with a wheel mounting flange for attaching a wheel to one end, and a hub wheel having a cylindrical small-diameter step portion extending in the axial direction on the outer periphery, and the hub wheel An inner member formed of at least one inner ring press-fitted into the small-diameter step portion through a predetermined scissors, and formed with a double-row inner rolling surface facing the double-row outer rolling surface on the outer periphery; and In a clearance measurement method for a wheel bearing device including a double row rolling element that is rotatably accommodated between a rolling surface of an inner member and the outer member via a cage, before and after caulking. Measure the height of the gear member from the reference plane and calculate the amount of change in height. Calculate the clearance reduction amount using a regression equation in which the relationship between elastic deformation and clearance reduction amount has been confirmed in advance, and subtract the clearance reduction amount from the bearing clearance before caulking to calculate the bearing clearance after caulking. .

  In this way, the height from the reference surface of the gear member before and after caulking is measured, and the amount of change in the height is determined by a regression equation in which the relationship between the elastic deformation amount and the clearance reduction amount is confirmed in advance. Since the bearing clearance after caulking is calculated by subtracting this clearance reduction amount from the bearing clearance before caulking, even if the bearing clearance after caulking is negative, it is indirectly preloaded. The amount can be controlled stably.

  A wheel bearing device according to the present invention has a vehicle body mounting flange integrally attached to a knuckle constituting a suspension device on an outer periphery, and an outer side in which a double row outer rolling surface is integrally formed on an inner periphery. And a hub wheel integrally having a wheel mounting flange for mounting a wheel at one end thereof and having a cylindrical small-diameter step portion extending in the axial direction on the outer periphery, and a small-diameter step portion of the hub wheel having a predetermined diameter An inner member comprising at least one inner ring that is press-fitted through a nip and having a double-row inner rolling surface facing the double-row outer rolling surface on the outer periphery; and the inner member and the outer member In a wheel bearing device comprising a double-row rolling element that is rotatably accommodated between both rolling surfaces of a side member via a cage, the end of the small-diameter step portion of the hub wheel is radially outward. The inner ring is shaped like a ring by a caulking portion formed by plastic deformation in the direction. The shaft is fixed in the axial direction with a predetermined bearing preload applied through the member, and the gear member is made of a steel material having a carbon content equal to or less than medium carbon steel, and is hardened to the core part by quenching. In the caulking process, excessive stress is generated in the gear member because the gear portion and the spline portion that meshes with the hub spline portion formed on the outer peripheral surface of the small diameter step portion of the hub wheel are formed on the inner periphery. Deformation and micro cracks can be prevented, and since the gear member is difficult to be plastically deformed by caulking, the amount of elastic deformation can be measured with high accuracy, and it is highly accurate and stable with little variation. Preload management can be performed.

  Further, the preload management method for a wheel bearing device according to the present invention integrally has a vehicle body mounting flange for mounting on a knuckle that constitutes a suspension device on the outer periphery, and a double row outer rolling surface is integrated on the inner periphery. An outer member formed integrally with a wheel mounting flange for attaching a wheel to one end, and a hub wheel having a cylindrical small-diameter step portion extending in the axial direction on the outer periphery, and the hub wheel An inner member formed of at least one inner ring press-fitted into the small-diameter step portion through a predetermined scissors, and formed with a double-row inner rolling surface facing the double-row outer rolling surface on the outer periphery; and In a method for measuring a clearance of a wheel bearing device including a double row rolling element that is rotatably accommodated between a rolling surface of an inner member and the outer member via a cage, The bearing clearance is measured and the base of the gear member before and after caulking Measure the height from the surface, and calculate the amount of change in the height using a regression equation in which the relationship between the amount of elastic deformation and the amount of clearance reduction has been confirmed in advance. Since the bearing clearance after caulking is calculated by subtracting the clearance reduction amount, the preload amount can be indirectly and stably managed even if the bearing clearance after caulking is negative.

It is a longitudinal section showing one embodiment of a wheel bearing device concerning the present invention. It is a longitudinal cross-sectional view which shows the bearing part of FIG. It is a principal part enlarged view which shows the crimping part of FIG. (A) is sectional drawing of the gear member which concerns on this invention, (b) is sectional drawing which shows the modification of (a). It is a longitudinal cross-sectional view which shows before the caulking of the wheel bearing apparatus which concerns on this invention. It is a longitudinal cross-sectional view which shows the conventional wheel bearing apparatus.

  An outer member integrally having a vehicle body mounting flange to be attached to a knuckle constituting a suspension device on the outer periphery, a double row tapered outer rolling surface formed integrally on the inner periphery, and a wheel on one end A hub wheel integrally having a wheel mounting flange for mounting a wheel and having a cylindrical small-diameter step portion extending in an axial direction from the wheel mounting flange via a shoulder portion on the outer periphery, and a small-diameter step portion of the hub wheel An inner member consisting of a pair of inner rings that are press-fitted through a predetermined squeeze and have a tapered inner rolling surface facing the outer rolling surface of the double row on the outer periphery, and the inner member and the In a wheel bearing device including a double row tapered roller that is rotatably accommodated via a cage between both rolling surfaces of an outer member, the end portion of the small-diameter step portion of the hub wheel is radially arranged The inner ring is fixed by a caulking portion formed by plastic deformation outward. It is fixed in the axial direction with a predetermined bearing preload applied via a gear-shaped gear member, and the gear member is made of a steel material having a carbon content of medium carbon steel or less and hardens to the core portion by quenching. And a spline portion that engages with a hub spline portion formed on an outer peripheral surface of a small diameter step portion of the hub wheel is formed on the outer periphery, and the surface hardness of the gear member is at least that of the hub wheel. It has a hardness difference of 130 HV.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
1 is a longitudinal sectional view showing an embodiment of a wheel bearing device according to the present invention, FIG. 2 is a longitudinal sectional view showing a bearing portion of FIG. 1, and FIG. 3 is a main part showing a caulking portion of FIG. FIG. 4A is a cross-sectional view of a gear member according to the present invention, FIG. 4B is a cross-sectional view showing a modification of FIG. 5A, and FIG. 5 shows a wheel bearing device according to the present invention. It is a longitudinal cross-sectional view which shows before crimping. In the following description, the side closer to the outer side of the vehicle when assembled to the vehicle is referred to as the outer side (left side in FIG. 1), and the side closer to the center is referred to as the inner side (right side in FIG. 1).

  This wheel bearing device is used on the drive wheel side, and includes an inner member 1 and an outer member 2, and double-row tapered rollers 3 and 3 accommodated between both members 1 and 2 so as to roll freely. Yes. The inner member 1 includes a hub ring 4 and a pair of inner rings 5 and 7 plastically coupled to the hub ring 4. The hub wheel 4 integrally has a wheel mounting flange 6 for mounting a wheel (not shown) at an end portion on the outer side, and has a cylindrical shape that extends in the axial direction from the wheel mounting flange 6 to the outer periphery via a shoulder portion 4a. The small diameter step 4b is formed. Further, hub bolts 6 a for fixing the wheels at the circumferentially equidistant positions of the wheel mounting flange 6 are planted.

  Each of the pair of inner rings 5 and 7 has a tapered inner rolling surface 5a formed on the outer periphery, and is press-fitted into the small-diameter step portion 4b of the hub wheel 4 via a predetermined squeeze. As shown in FIG. 2 in an enlarged manner, large flange portions 5b and 7b for guiding the tapered roller 3 are formed on the large diameter side of the inner rolling surface 5a, and the tapered roller 3 is formed on the small diameter side. Of the back-to-back type that is set in a state in which the small edge portions 5c and 7c are formed to prevent the falling off of the inner ring 5 and the small end surfaces 5d and 7d (front end surfaces) of the inner rings 5 and 7 are abutted with each other. Conical roller bearings are configured.

  The outer member 2 integrally has a vehicle body mounting flange 2b to be attached to a knuckle (not shown) on the outer periphery, and is a tapered double row outer rolling surface 2a, 2a opened outward on the inner periphery. Are integrally formed. The double-row tapered rollers 3 and 3 are accommodated between the rolling surfaces via a cage 8 so as to freely roll. Further, an annular groove 9 is formed on the outer diameter surface fitted into the knuckle, and an elastic ring (not shown) such as an O-ring is attached to the annular groove 9, thereby airtightness of the fitting portion with the knuckle. Can be improved.

  The hub wheel 4 is formed of medium-high carbon steel (carbon steel for SC system mechanical structure of JIS standard) containing 0.40 to 0.80 wt% of carbon such as S53C, and has a high frequency extending from the shoulder 4a to the small diameter step 4b. A predetermined hardened layer is formed in the range of surface hardness of 58 to 64 HRC by quenching. Further, the inner rings 5 and 7 and the tapered roller 3 are made of high carbon chrome bearing steel such as SUJ2, and are hardened in the range of 58 to 64 HRC to the core part by quenching. In addition, the crimping part 10 mentioned later is used as the unhardened part with the surface hardness after forging. This facilitates caulking and prevents the occurrence of microcracks during processing, and has sufficient mechanical strength against the rotational bending load applied to the wheel mounting flange 6, and the durability of the hub wheel 4. Improves.

  The outer member 2 is formed of medium and high carbon steel containing carbon of 0.40 to 0.80 wt% such as S53C, as in the case of the hub wheel 4, and at least the double-row outer raceway surfaces 2a and 2a are formed on the surface by induction hardening. A predetermined curing process is performed in the range of 58 to 64 HRC. Seals 11, 11 are attached to the opening of the annular space formed between the outer member 2 and the inner rings 5, 7, leakage of the lubricating grease sealed inside the bearing, rainwater, dust, etc. from the outside Is prevented from entering the inside of the bearing.

  The seal 11 is constituted by a so-called pack seal composed of a slinger 12 and an annular seal plate 13 arranged to face each other. Slinger 12 can be an austenitic stainless steel plate (JIS standard SUS304, etc.), a ferritic stainless steel plate (JIS standard SUS430, etc.), or a rust-proof cold rolled steel plate (JIS standard SPCC, etc.). And a cylindrical portion 12a having a substantially L-shaped cross section by press working and press-fitted into the large collar portion 7b (5b) of the inner rings 5 and 7, and a standing plate portion extending radially outward from the cylindrical portion 12a 12b.

  On the other hand, the seal plate 13 includes a cored bar 14 fitted into the end of the outer member 2 and a seal member 15 integrally joined to the cored bar 14 by vulcanization adhesion. The cored bar 14 is formed in a substantially L-shaped cross section by pressing from an austenitic stainless steel plate or a cold-rolled steel plate that has been rust-proofed.

  The seal member 15 is made of synthetic rubber such as NBR (acrylonitrile-butadiene rubber), and integrally includes a pair of side lips 15a and 15b extending obliquely outward in the radial direction and a grease lip 15c extending inclined inward of the bearing. Have. The side lips 15a and 15b are in sliding contact with the side surface of the standing plate portion 12b of the slinger 12 via a predetermined axial shimiro, and the grease lip 15c is slid onto the cylindrical portion 12a of the slinger 12 via a predetermined radial shimillo. Touching. In addition to the exemplified NBR, the seal member 15 is made of, for example, HNBR (hydrogenated acrylonitrile butadiene rubber), EPDM (ethylene propylene rubber), etc., which have excellent heat resistance, and heat resistance and chemical resistance. Examples thereof include ACM (polyacrylic rubber), FKM (fluororubber), and silicon rubber, which are excellent in the above.

  In the present embodiment, the rotational speed sensor 21 is inserted between the double row outer rolling surfaces 2a, 2a of the outer member 2 into a sensor insertion hole 22 formed so as to penetrate in the radial direction. This rotational speed sensor 21 incorporates a magnetic detecting element such as a Hall element, a magnetoresistive element (MR element) or the like that changes its characteristics according to the flow direction of magnetic flux, and a waveform shaping circuit that adjusts the output waveform of this magnetic detecting element. The synthetic resin is integrally molded by injection molding. And it has the shaft-shaped insertion part 21a inserted in the sensor insertion hole 22, and the non-insertion part 21b located in the exterior of the outer member 2. As shown in FIG. An annular groove 23 is formed on the outer periphery of the insertion portion 21a, and an elastic ring 24 made of an O-ring or the like is attached to the annular groove 23. Moreover, the non-insertion part 21b is formed in the shape seated on the sensor attachment part 25 of the outer member 2, and is fastened via the attachment piece (not shown) extended to a side.

  On the other hand, a pulsar ring 26 facing the rotational speed sensor 21 via a predetermined radial clearance (air gap) is externally fitted and fixed to the outer periphery of the inner ring 5 on the small flange portion 5c side. The pulsar ring 26 is formed in the shape of a spur gear composed of an uneven portion 26a. Thereby, the direction of the magnetic field alternately changes on the circumference along with the rotation of the hub wheel 4, and the rotational speed of the wheel can be detected via the rotational speed sensor 21.

  The integration of the hub wheel 4 and the inner rings 5 and 7 is achieved by pressing the inner rings 5 and 7 into the small-diameter step portion 4b of the hub wheel 4 via a predetermined shimiro, and the end of the small-diameter step portion 4b in the radial direction This is performed by a caulking portion 10 formed by plastic deformation outward (see FIG. 1).

  In the present embodiment, the double row tapered roller bearing in which the rolling element is composed of the tapered roller 3 is exemplified. However, the wheel bearing device according to the present invention is not limited thereto, and for example, although not illustrated, a ball is used for the rolling element. It may be composed of double row angular contact ball bearings.

  Further, as shown in FIG. 1, a shaft portion of an outer joint member constituting a constant velocity universal joint (not shown) is rotatably supported on the inner circumference of the hub wheel 4 via rolling bearings 16 and 17. Out of these rolling bearings 16, 17, the outer side rolling bearing 16 is a deep groove ball bearing, and the inner side rolling bearing 17 is a shell-shaped needle roller bearing.

  Here, as shown in an enlarged view in FIG. 3, the inner ring 7 is fixed to the hub wheel 4 in the axial direction by the crimping portion 10 via a ring-shaped gear member 18. The gear member 18 is formed with a gear portion 18 a on the outer periphery and a spline portion 18 b on the inner periphery, and the inner spline portion 18 b is formed on the outer peripheral surface on the inner side of the small-diameter step portion 4 b of the hub wheel 4. Meshed with the hub spline portion 4c. The gear member 18 is pressed toward the inner ring 7 by the crimping pressure from the crimping portion 10 that is in contact with the end surface on the inner side, and the gear member 18 and the gear member 18 are pressed by the crimping pressure acting from the crimping portion 10. The pair of inner ring members 5 and 7 are securely fixed to the hub ring 4.

  A ring-shaped slide gear 20 in which the gear portion 18a of the gear member 18 is engaged with the gear portion 19 of the outer joint member (not shown) is selectively engaged by sliding in the axial direction. A driving force is transmitted from the constant velocity universal joint to the wheel via the inner ring 7 and the hub wheel 4 in a state where the gear member 18 and the gear portion 19 of the outer joint member are connected via the slide gear 20. That is, at this time, the wheel supported by the hub wheel 4 is a driving wheel. In the state where the slide gear 20 is not engaged with the gear member 18, the driving force is not transmitted to the wheel, and at this time, the wheel supported by the hub wheel 4 becomes a driven wheel, and switching between four wheels and two wheels is selective. To be done.

  In the present embodiment, the gear member 18 is formed from a steel material having a carbon content equal to or less than that of medium carbon steel. Specifically, it is formed from a steel material containing 0.15 to 0.45 wt% carbon, preferably 0.38 to 0.43 wt% carbon. And hardening processing is carried out in the range of 40-55 HRC (392-600 HV) to the core part by sublimation quenching (quenching tempering).

  Thus, with respect to the hub wheel 4 made of medium-high carbon steel such as S53C, the amount of Cr in the gear member 18 increases to approximately 0.09 to 0.12 wt%, and the tenacity increases. In addition, when the carbon amount is high-carbon steel, the hardness becomes about HRC60 (700HV). However, in the present invention, the carbon content is hardened by sub-firing from a steel material having a medium carbon steel or less. A gear portion having an appropriate hardness can be obtained. That is, a hardness difference of about 132 to 340 HV can be made with respect to the surface hardness 260 HV of the crimped portion 10, and not only the gear portion 18 a and the spline portion 18 b but also a desired strength can be ensured. Therefore, in the caulking process, it is possible to prevent excessive stress from being generated in the gear member 18 to cause deformation and micro cracks, and when the caulking portion 10 is formed, the small-diameter step portion 4b of the hub wheel 4 is formed. Can be plastically deformed radially outward to prevent caulking defects such as microcracks from occurring in the caulking portion 10, and a bearing preload that is initially set over a long period of time can be prevented. Can be maintained.

  In addition, as a material of the gear member 18, brittleness can be suppressed by adopting chromium molybdenum steel such as SCM440 or SCM430 to which Mo (molybdenum) is added approximately 0.15 to 0.3 wt%. It is possible to reliably prevent the occurrence of micro cracks during the caulking process and to ensure the strength when a driving force is applied.

  Moreover, in this embodiment, as shown to Fig.4 (a), the tooth root 18ab of the gear part 18a may be formed in the single circular arc which consists of the curvature radius R, and it shows to (b). Thus, the tooth bottom 18ab ′ of the gear portion 18a ′ may be formed in a shape having two curvature radii R. Thereby, the force at the time of caulking is disperse | distributed and the crack which generate | occur | produces in the tooth bottom 18ab and 18ab 'can be prevented. The compound R is carried out when a single R cannot cope with the R because no R is attached to the portion that contacts the other gear.

  In the present embodiment, the bearing preload is managed in the caulking process. The inner ring 7 and the gear member 18 are elastically deformed by the caulking process, and the bearing clearance is reduced by elastically deforming them. Since there is a correlation between the elastic deformation amount and the clearance reduction amount, a regression equation is prepared in advance by conducting a test of the elastic deformation amount and the clearance reduction amount in a bearing having the same specifications.

  Then, the bearing clearance before caulking is measured, and the height H0 of the gear member 18 before caulking is measured. That is, as shown in FIG. 5, the end portion of the small diameter step portion 4b of the hub wheel 4 ′ is formed in a cylindrical shape, the spline portion 18b of the gear member 18 is formed on the hub spline portion 4c, and the large end surface 7e of the inner ring 7 is formed. The height H0 of the gear member 18 is measured in the closely contacted state. Thereafter, the height H1 of the gear member 18 after caulking is measured, and the amount of change in height (elastic deformation amount) ΔH = H0−H1 is calculated by calculating a clearance reduction amount by a regression equation confirmed in advance. Subtract this clearance reduction from the bearing clearance before tightening to finally calculate the bearing clearance after crimping.

  Since the bearing clearance after caulking is set to a negative clearance due to preload, it cannot be measured directly. Thus, the height of the gear member 18 before and after the caulking is measured, the elastic deformation amount of the inner ring 7 and the gear member 18 is calculated, and the preload amount can be indirectly managed from the elastic deformation amount. In the present invention, since the gear member 18 is difficult to be plastically deformed by caulking, the amount of elastic deformation can be measured with high accuracy, and the preload management can be performed stably with high accuracy while suppressing variations.

  The embodiment of the present invention has been described above, but the present invention is not limited to such an embodiment, and is merely an example, and various modifications can be made without departing from the scope of the present invention. Of course, the scope of the present invention is indicated by the description of the scope of claims, and further, the equivalent meanings described in the scope of claims and all modifications within the scope of the scope of the present invention are included. Including.

  In the wheel bearing device according to the present invention, a gear member that selectively switches between four wheels and two wheels is fixed to an inner member having a hub wheel and an inner ring fitted to the hub wheel. It can be applied to a wheel bearing device having a third generation structure.

DESCRIPTION OF SYMBOLS 1 Inner member 2 Outer member 2a Outer rolling surface 2b Car body mounting flange 3 Tapered roller 4, 4 'Hub wheel 4a Shoulder part 4b Small diameter step part 4c Hub spline part 5, 7 Inner ring 5a Inner rolling surface 5b, 7b Large Fence part 5c, 7c Small flange part 5d, 7d Small end face 7e Large end face 6 Wheel mounting flange 6a Hub bolt 8 Cage 9 Annular groove 10 Clamping part 11 Seal 12 Slinger 12a Cylindrical part 12b Standing plate part 13 Sealing plate 14 Core 15 Seal member 15a, 15b Side lip 15c Grease lip 16, 17 Rolling bearing 18, 18 'Gear member 18a, 18a' Gear part 18ab, 18ab 'Gear part bottom 18b Spline part 19 Outer joint member gear part 20 Slide gear 21 Rotational speed sensor 21a Insertion part 21b Non-insertion part 22 Sensor insertion hole 23 Annular groove 24 Elastic ring 25 Sensor attachment part 26 Saling 26a Concavity and convexity 50 Outer member 50a Outer rolling surface 51 Inner member 52 Tapered roller 53 Wheel mounting flange 54 Hub wheel 54a, 56b Spline-like portion 54b Clamping portion 55, 56 Inner ring 55a Inner rolling surface 56a, 59 Gear Portions 57, 58 Bearing 60 Slide gear H0 Height of gear member before caulking H1 Height of gear member after caulking ΔH Height change amount R Radius of curvature of gear base

Claims (8)

An outer member integrally having a vehicle body mounting flange for being attached to a knuckle constituting a suspension device on the outer periphery, and an outer rolling surface of a double row integrally formed on the inner periphery;
A hub wheel integrally having a wheel mounting flange for mounting a wheel at one end and having a cylindrical small-diameter stepped portion extending in the axial direction on the outer periphery, and a small diameter stepped portion of the hub wheel via a predetermined squeezing An inner member formed of at least one inner ring press-fitted and formed with a double-row inner rolling surface facing the double-row outer rolling surface on the outer periphery;
In a wheel bearing device comprising a double-row rolling element that is accommodated so as to roll freely between both rolling surfaces of the inner member and the outer member via a cage,
In a state where a predetermined bearing preload is applied to the inner ring through a ring-shaped gear member by a caulking portion formed by plastically deforming an end portion of the small-diameter step portion of the hub ring radially outward. Fixed,
The gear member is made of a steel material having a carbon content of medium carbon steel or less, and is hardened up to the core by quenching, and formed on the outer periphery of the gear portion on the outer periphery and on the outer peripheral surface of the small diameter step portion of the hub wheel on the inner periphery. A wheel bearing device characterized in that a spline portion meshing with a hub spline portion is formed, and the gear portion and the spline portion are set to have the same hardness.   The wheel bearing device according to claim 1, wherein a surface hardness of the gear member has a hardness difference of at least 130 HV from the hub wheel.   3. The wheel bearing device according to claim 1, wherein the gear member is contained in 0.09 to 0.12 wt% of Cr, and the surface hardness is set in a range of 392 to 600 HV.   The wheel bearing device according to any one of claims 1 to 3, wherein the gear member is formed of a steel material made of carbon of 0.15 to 0.45 wt%.   The wheel bearing device according to any one of claims 1 to 4, wherein the gear member is made of chromium molybdenum steel containing 0.15 to 0.3 wt% of Mo.   The wheel bearing device according to any one of claims 1 to 5, wherein a tooth bottom of a gear portion of the gear member is formed in an arc shape having a predetermined radius of curvature.   The hub wheel is made of medium and high carbon steel containing carbon of 0.40 to 0.80 wt%, and has a surface hardness of 58 to 64 HRC by induction hardening from the inner side base portion of the wheel mounting flange to the small diameter step portion. 2. The wheel bearing device according to claim 1, wherein a predetermined hardened layer is formed in the range, and the caulking portion is an unquenched portion having the surface hardness after forging. An outer member integrally having a vehicle body mounting flange for being attached to a knuckle constituting a suspension device on the outer periphery, and an outer rolling surface of a double row integrally formed on the inner periphery;
A hub wheel integrally having a wheel mounting flange for mounting a wheel at one end and having a cylindrical small-diameter stepped portion extending in the axial direction on the outer periphery, and a small diameter stepped portion of the hub wheel via a predetermined squeezing An inner member formed of at least one inner ring press-fitted and formed with a double-row inner rolling surface facing the double-row outer rolling surface on the outer periphery;
In the preload management method for a wheel bearing device comprising a double row rolling element that is rotatably accommodated between both rolling surfaces of the inner member and the outer member via a cage,
The bearing clearance before caulking is measured, and the height from the reference surface of the gear member before and after caulking is measured, and the relationship between the amount of elastic deformation and the amount of clearance reduction is confirmed in advance. A preload management method for a wheel bearing device, wherein a clearance reduction amount is calculated by a regression equation, and the bearing clearance after crimping is calculated by subtracting the clearance reduction amount from the bearing clearance before crimping.

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