JP2013082351A - Wheel bearing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wheel bearing apparatus that eases rapid slipping occurring between an inward member and a shoulder of an outer joint member, and prevents generation of stick slip noise over the long period of time.SOLUTION: An end face 6a of a caulking part 6 is formed on a flat surface, and a cap 18 made of the steel plate which includes a disk shape abutting part 18a is set while being held between this end face 6a and the shoulder 16 of the outer joint member 14. The low friction resin film layer in which the fluororesin of 40-50 wt.% is mixed is formed by coating on the surface of the abutting part 18a of this cap 18, and the surface roughness Ra of the shoulder 16 of the outer joint member 14 that abuts the cap 18 and the end face 6a of the caulking part 6 is set to ≤3.2 μm.

Description

  The present invention relates to a wheel bearing device for supporting a wheel of a vehicle such as an automobile, and more specifically, a drive wheel (a front wheel of an FF vehicle, FR) provided with a wheel bearing and a constant velocity universal joint and mounted on an independent suspension type suspension. The present invention relates to a wheel bearing device that rotatably supports a rear wheel of a car or an RR car and all wheels of a 4WD car) with respect to a suspension device.

  A power transmission device that transmits engine power of a vehicle such as an automobile to a wheel transmits power from the engine to the wheel, and also causes radial or axial displacement from the wheel that occurs when the vehicle bounces or turns when traveling on a rough road. For example, one end of the drive shaft interposed between the engine side and the drive wheel side is connected to the differential through a sliding type constant velocity universal joint, and the like. The end is connected to the drive wheel via a wheel bearing device including a fixed type constant velocity universal joint.

  Various types of wheel bearing devices have been proposed in the past, and for example, those shown in FIG. 13 are known. This wheel bearing device 50 has a vehicle body mounting flange 51b integrally attached to the vehicle body on the outer periphery, and an outer member 51 in which double row outer rolling surfaces 51a, 51a are integrally formed on the inner periphery. , A wheel mounting flange 54 for mounting a wheel (not shown) at one end is integrally formed, an inner rolling surface 52a facing one of the double row outer rolling surfaces 51a, 51a on the outer periphery, and the inner side A hub wheel 52 having a cylindrical small-diameter stepped portion 52b extending in the axial direction from the rolling surface 52a, and a small-diameter stepped portion 52b of the hub wheel 52 are press-fitted, and double row outer rolling surfaces 51a and 51a are arranged on the outer periphery. An inner member 55 comprising an inner ring 53 formed with an inner raceway surface 53a opposite to the other of the inner raceway 53, and between the raceway surfaces of the inner member 55 and the outer member 51 via a retainer 56, 56. Double row balls 57, 57 accommodated freely , And a seal 58, 59 attached to the annular openings formed between the outer member 51 and inner member 55.

  The inner ring 53 is axially fixed to the hub wheel 52 by a caulking portion 60 formed by plastically deforming the end of the small-diameter stepped portion 52 b of the hub wheel 52 radially outward. A constant velocity universal joint 61 is connected. The outer joint member 62 of the constant velocity universal joint 61 has a shoulder portion 63 that forms the bottom of the cup-shaped mouth portion, and extends axially from the shoulder portion 63 so that torque can be transmitted to the hub wheel 52 via the serration 64a. The hub ring 52 and the outer joint member 62 are detachably coupled in the axial direction via the fixing nut 65 with the stem part 64 fitted therein integrally, the shoulder part 63 being in contact with the caulking part 60. ing.

  It is known that torque is applied to the wheels of such a vehicle from the engine via a sliding type constant velocity universal joint 61, and the drive shaft is twisted. As a result, a relative difference due to twisting occurs between the caulking portion 60 of the hub wheel 52 and the shoulder portion 63 of the outer joint member 62. The axial force generated by tightening the nut 65 causes the contact surfaces of the caulking portion 60 and the shoulder portion 63 to move together with frictional resistance. However, when the engine rotates at a low speed, for example, when the vehicle starts, a larger torque is applied. When a large twist occurs in the drive shaft, the contact surface between the outer joint member 62 and the inner member 55 cannot withstand the frictional resistance, causing a sudden slip and a stick-slip sound.

  As a countermeasure, in the wheel bearing device 50, a synthetic resin cap 66 is attached to the caulking portion 60, and the cap 66 includes a disk-like contact portion 66a and an inner diameter of the contact portion 66a. A cylindrical fitting portion 66b extending in the axial direction from the portion and a cylindrical flange 66c extending in the axial direction from the outer diameter portion of the contact portion 66a, and the end surface of the crimping portion 60 is formed in a flat surface. In addition, the fitting portion 66b of the cap 66 is press-fitted and fixed to the inner diameter of the caulking portion 60 while being sandwiched between the caulking portion 60 and the shoulder 63 of the outer joint member 62.

  As a result, even when a torque is applied to the drive shaft and a large twist occurs in the outer joint member 62, the cap 66 has an effect of reducing the frictional resistance, so that the inner member 55 and the shoulder 63 are brought into contact with each other. The surface can be slid to alleviate sudden slip, and the occurrence of stick-slip noise can be prevented, and the cap 66 can be easily attached to the inner member 55 with one touch. It is possible to prevent the cap 66 from falling off the inner member 55 and improve workability (see, for example, Patent Document 1).

  In this conventional wheel bearing device 50, the resin cap 66 is deformed by the axial force that fastens the constant velocity universal joint 61, wears during use, and becomes loose with the caulking portion 60. There was a problem that it was difficult to maintain a desired effect over a period of time. In order to suppress such deformation of the resin cap 66, a steel plate cap having a fluororesin coating layer or the like and a plate having a thickness of 0.5 mm to 2 mm interposed is also known (Patent Literature). 2).

JP 2010-158925 A JP 2009-234289 A

  However, even if a fluororesin coating layer or the like is formed on a steel plate cap, the coating layer may be worn if the surface properties of the mating member such as the caulking portion 60 that contacts the cap or the shoulder portion 63 of the outer joint member 62 are poor. Otherwise, the slip characteristics may deteriorate and stick-slip noise may occur.

  The present invention has been made in view of such circumstances, alleviating a sudden slip that occurs between the inner member and the shoulder of the outer joint member, and generating stick-slip noise over a long period of time. It aims at providing the bearing device for wheels which prevented.

  In order to achieve such an object, the invention according to claim 1 of the present invention includes an outer member in which a double row outer rolling surface is integrally formed on the inner periphery, and a wheel for attaching a wheel to one end. A hub ring having an integral mounting flange and having a cylindrical small-diameter step portion extending in the axial direction on the outer periphery and serrations formed on the inner periphery, and at least one press-fitted into the small-diameter step portion of the hub ring An inner member formed of an inner ring and formed with a double row inner rolling surface facing the outer row rolling surface of the double row, and a cage between both rolling surfaces of the inner member and the outer member. A double row rolling element accommodated in a freely rotatable manner, and seals mounted on both side openings of an annular space formed between the outer member and the inner member, A constant velocity universal joint is connected, and the outer joint member of the constant velocity universal joint is a cup-shaped mouse. And a shoulder portion that forms the bottom of the mouth portion, and a stem portion that extends in the axial direction from the shoulder portion and is fitted into the hub wheel so as to transmit torque via serration, In the wheel bearing device in which the hub wheel and the outer joint member are detachably coupled to each other in the axial direction via a fixing nut in a state of being in contact with the inner member, the end surface of the inner member and the outer joint member A steel plate cap provided with a disk-shaped contact portion is interposed between the cap and the shoulder portion, and a low friction resin coating is provided on at least one surface of the contact portion of the cap. The layer is formed by painting, and the surface roughness of the shoulder portion of the outer joint member that contacts the cap and the end surface of the inner member is set to Ra 3.2 μm or less.

  As described above, in the wheel bearing device in which the outer joint member is capable of transmitting torque to the hub wheel via the serration and is detachably coupled in the axial direction, the end surface of the inner member and the shoulder of the outer joint member A steel plate cap provided with a disk-shaped contact portion is interposed in a state of being sandwiched therebetween, and a low friction resin coating layer is applied to at least one surface of the contact portion of the cap by painting. Since the surface roughness of the shoulder portion of the outer joint member that contacts the cap and the end surface of the inner member is set to Ra 3.2 μm or less, it is deformed by the axial force that fastens the constant velocity universal joint. In addition to preventing wear during use and an increase in play between the mating member and the shoulder of the inner member and the outer joint member, it is possible to alleviate a sudden slip, and for a long period of time. The stick-slip sound It is possible to provide a wheel bearing apparatus which prevents.

  Preferably, as in the invention according to claim 2, the low friction resin coating layer is blended with 40 to 50% by weight of a fluororesin, 45 to 55% by weight of a matrix resin, and 1 to 10% by weight of graphite. For example, it has excellent friction and wear characteristics, can impart non-adhesiveness to the coating layer with low friction, and has heat resistance that can withstand the operating temperature atmosphere of the sliding member.

  Further, as in the invention according to claim 3, as a base of the low friction resin coating layer, if the surface of the cap is preliminarily subjected to shot blasting, the adhesion can be increased, and for a long period of time. The low friction resin coating layer can be prevented from peeling over.

  According to a fourth aspect of the present invention, the inner ring is fixed in the axial direction by a caulking portion formed by plastically deforming an end portion of the small-diameter step portion of the hub wheel radially outward, and the caulking portion The end surface of the tightening portion may be formed as a flat surface, and the cap may be sandwiched between the end surface of the crimping portion and the shoulder portion of the outer joint member.

  According to a fifth aspect of the present invention, the cap includes a cylindrical fitting portion that extends in an axial direction from the inner diameter portion of the contact portion, and the fitting portion is an inner diameter surface of the caulking portion. May be fitted.

  According to a sixth aspect of the present invention, the cap includes a cylindrical flange that extends in the axial direction from the outer diameter portion of the contact portion, and a latch that protrudes radially inward from the flange. And an inner diameter of the locking portion is set to be slightly smaller than an outer diameter of the crimping portion, and the cap is attached to the crimping portion by elastically deforming the locking portion. As a result, the rigidity of the cap can be increased to improve the strength, and the cap can be prevented from falling off the crimped portion.

  Further, as in the seventh aspect of the invention, if a plurality of slits extending in the axial direction are formed at equal intervals in the circumferential direction of the flange portion and the locking portion of the cap, the cap can be easily attached to the caulking portion with one touch. In addition, the cap can be prevented from falling off the caulking portion in the assembly process, and the number of assembling steps can be improved.

  Further, as in the invention described in claim 8, the cap is interposed between the large end surface of the inner ring and a shoulder portion of the outer joint member, and the cap is A cylindrical fitting portion that extends in the axial direction from the inner diameter portion of the contact portion may be provided, and the fitting portion may be fitted to the inner diameter surface of the small-diameter step portion or the inner ring.

  According to a ninth aspect of the present invention, the cap includes a cylindrical fitting portion that extends in an axial direction from the outer diameter portion of the contact portion, and the fitting portion has an outer diameter of the inner ring. It may be fitted.

  According to a tenth aspect of the present invention, the cap includes a cylindrical fitting portion extending in an axial direction from the outer diameter portion of the contact portion, and the fitting portion is a shoulder of the outer joint member. It may be fitted to the part.

  Further, as in the invention according to claim 11, if the material of the cap is formed by press working from a stainless steel plate having rust prevention ability, and the low friction resin coating layer is formed on the contact portion, The coating range can be limited, and the cost can be reduced.

  In addition, as in the invention described in claim 12, if the material of the cap is formed from a cold-rolled steel plate by pressing and the low friction resin coating layer is formed on the entire surface of the cap, the cost is low. The press workability is improved, and the low friction resin coating layer can prevent the cap itself from rusting over a long period of time.

  Further, as in the invention described in claim 13, the shoulder portion of the outer joint member may be subjected to a hardening treatment in a range of 50 to 64 HRC by induction hardening, and then ground.

  Further, as in the invention described in claim 14, the end face of the caulking portion may be turned after swing caulking.

  The wheel bearing device according to the present invention integrally has an outer member integrally formed with a double row outer rolling surface on the inner periphery, and a wheel mounting flange for mounting the wheel on one end, and on the outer periphery. The double-row outer roll comprises a hub ring formed with a cylindrical small diameter step portion extending in the axial direction and serrations formed on the inner periphery, and at least one inner ring press-fitted into the small diameter step portion of the hub ring. An inner member in which a double row of inner rolling surfaces facing the running surface is formed, and a compound member that is rotatably accommodated via a cage between both rolling surfaces of the inner member and the outer member. A rolling element in a row and a seal attached to both side openings of an annular space formed between the outer member and the inner member, and a constant velocity universal joint is connected to the hub wheel, The outer joint member of the constant velocity universal joint forms a cup-shaped mouth portion and a bottom portion of the mouth portion. A shoulder portion and a stem portion extending in an axial direction from the shoulder portion and fitted into the hub wheel so as to be able to transmit torque via serrations are integrally formed, and the shoulder portion is in a state of abutting with the inner member. In the wheel bearing device in which the hub wheel and the outer joint member are detachably coupled in the axial direction via a fixing nut, the hub wheel and the outer joint member are sandwiched between the end surface of the inner member and the shoulder of the outer joint member. In the state, a steel plate cap provided with a disk-shaped contact portion is interposed, and a low friction resin coating layer is formed by painting on at least one surface of the surface of the contact portion of the cap, Since the surface roughness of the shoulder portion of the outer joint member abutting on the cap and the end surface of the inner member is set to Ra 3.2 μm or less, it is used when deformed by an axial force for fastening the constant velocity universal joint. Plays with the mating member due to wear A wheel bearing device that prevents the occurrence of stick-slip noise over a long period of time by preventing a sudden slip that occurs between the inner member and the shoulder of the outer joint member. Can be provided.

It is a longitudinal section showing a 1st embodiment of a bearing device for wheels concerning the present invention. It is a principal part enlarged view which shows the cap mounting part of FIG. It is a graph which shows the test result which evaluates the wear characteristic of the low friction resin film layer concerning the present invention. It is a principal part enlarged view which shows the modification of the cap of FIG. It is a principal part enlarged view which shows the other modification of the cap of FIG. It is a principal part enlarged view which shows the other modification of the cap of FIG. It is a principal part enlarged view which shows the modification of the cap of FIG. It is a longitudinal cross-sectional view which shows 2nd Embodiment of the wheel bearing apparatus which concerns on this invention. It is a principal part enlarged view which shows the cap mounting part of FIG. It is a principal part enlarged view which shows the modification of the cap of FIG. It is a principal part enlarged view which shows the modification of the cap of FIG. It is a principal part enlarged view which shows the modification of the cap of FIG. 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 the vehicle body on the outer periphery, a double row outer rolling surface formed integrally on the inner periphery, and a wheel mounting flange for mounting a wheel on one end A hub wheel integrally formed and formed on the outer periphery with an inner rolling surface facing one of the double row outer rolling surfaces, and a cylindrical small-diameter stepped portion extending in the axial direction from the inner rolling surface; and An inner member comprising an inner ring press-fitted into a small-diameter step portion of the hub wheel and having an inner rolling surface facing the other of the outer rolling surfaces of the double row on the outer periphery, and the inner member and the outer member Attached to both side openings of an annular space formed between the outer member and the inner member, and a double row rolling element accommodated between the rolling surfaces of the member via a cage. A caulking portion formed by plastically deforming the end portion of the small diameter step portion radially outward. The inner ring is fixed in an axial direction with respect to the hub ring, and a constant velocity universal joint is connected to the hub ring. An outer joint member of the constant velocity universal joint includes a cup-shaped mouth portion and the mouth portion. And a stem portion extending in an axial direction from the shoulder portion and fitted in the hub wheel so as to be able to transmit torque via serration, and the shoulder portion is the caulking portion. In the wheel bearing device in which the hub wheel and the outer joint member are detachably coupled in the axial direction via a fixing nut, the end surface of the crimped portion is formed as a flat surface. A steel plate cap provided with a disk-like contact portion is interposed between the outer joint member and the shoulder portion, and the surface of the contact portion of the cap is 40 to 50 wt. % Low-friction resin coating layer formed by painting With the surface roughness of the end surface of the shoulder portion and the caulked portion of the outer joint member abutting on the cap is set below Ra3.2Myuemu.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a longitudinal sectional view showing a first embodiment of a wheel bearing device according to the present invention, FIG. 2 is an enlarged view of a main part showing a cap mounting portion of FIG. 1, and FIG. FIG. 4 is a graph showing a test result for evaluating the wear characteristics of the friction resin coating layer, FIG. 4 is an enlarged view of a main part showing a modification of the cap of FIG. 2, and FIG. 5 is a diagram showing another modification of the cap of FIG. FIG. 6 is an enlarged view of a main part showing another modification of the cap of FIG. 2, and FIG. 7 is an enlarged view of the main part showing a modification of the cap of FIG. 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 referred to as a third generation for driving wheels, and is a double row rolling element (ball) accommodated in a freely rollable manner between the inner member 1, the outer member 10, and both members 1, 10. The constant velocity universal joint 13 is detachably coupled. The inner member 1 includes a hub ring 2 and an inner ring 3 press-fitted into the hub ring 2.

  The hub wheel 2 integrally has a wheel mounting flange 4 for attaching a wheel (not shown) to an end portion on the outer side, one (outer side) inner rolling surface 2a on the outer periphery, and this inner rolling. A cylindrical small diameter step portion 2b extending in the axial direction from the surface 2a is formed, and a serration (or spline) 2c for torque transmission is formed on the inner periphery. Hub bolts 5 for attaching the wheels are planted at circumferentially equidistant positions of the wheel mounting flanges 4.

  The hub wheel 2 is made of medium and high carbon steel containing 0.40 to 0.80% by weight of carbon, such as S53C, and a base portion serving as a seal land portion in which an inner rolling surface 2a and an outer side seal 11 described later come into sliding contact. 7 to a small diameter step portion 2b, the surface hardness is set in the range of 58 to 64HRC by induction hardening. In addition, the caulking part 6 to be described later is an unquenched part having a surface hardness of 30 HRC or less after forging. Then, the inner ring 3 with the other (inner side) inner rolling surface 3a formed on the outer periphery is press-fitted into the small-diameter step portion 2b of the hub wheel 2 via a predetermined shimiro, and the end portion of the small-diameter step portion 2b is radially inserted The inner ring 3 is fixed in the axial direction with respect to the hub wheel 2 in a state where a predetermined bearing preload is applied by a caulking portion 6 formed by plastic deformation (oscillation caulking) outward. On the other hand, the inner ring 3 and the rolling element 8 are made of high carbon chrome steel such as SUJ2, and are hardened in the range of 58 to 64 HRC up to the core by quenching.

  The outer member 10 integrally has a vehicle body mounting flange 10b for mounting to the vehicle body (not shown) on the outer periphery, and has a double row facing the inner rolling surfaces 2a and 3a of the inner member 1 on the inner periphery. Outer rolling surfaces 10a and 10a are integrally formed. The outer member 10 is made of medium-high carbon steel containing 0.40 to 0.80% by weight of carbon such as S53C, and at least the double row outer rolling surfaces 10a and 10a have a surface hardness of 58 to 64HRC by induction hardening. Curing treatment is performed in the range of. And the double-row rolling elements 8 and 8 are accommodated so that rolling is possible via the holder | retainers 9 and 9 between each rolling surface 10a, 2a and 10a, 3a. Seals 11 and 12 are attached to the opening of the annular space formed between the outer member 10 and the inner member 1 to prevent leakage of the lubricating grease sealed inside the bearing and from the outside. It prevents rainwater and dust from entering the bearing.

  In the present embodiment, a wheel bearing device constituted by a double row angular contact ball bearing using a ball as the rolling element 8 has been exemplified. However, the present invention is not limited to this. For example, the rolling element 8 includes a double roller using a tapered roller. It may be composed of a row of tapered roller bearings. Although the third generation structure in which one inner rolling surface 2a is directly formed on the outer periphery of the hub wheel 2 is illustrated here, although not shown, a pair of inner rings are press-fitted into the small-diameter step portion of the hub wheel. A so-called first generation or second generation structure may also be used.

  The constant velocity universal joint 13 includes an outer joint member 14, a joint inner ring, a cage and a torque transmission ball (not shown). The outer joint member 14 is made of medium and high carbon steel containing 0.40 to 0.80% by weight of carbon such as S53C, and has a cup-shaped mouth portion 15, a shoulder portion 16 that forms the bottom of the mouth portion 15, and the shoulder portion. A stem portion 17 extending in the axial direction from the portion 16 is integrally provided. The stem portion 17 has a serration (or spline) 17a that engages with the serration 2c of the hub wheel 2 on the outer periphery, and a male screw 17b formed at the end of the serration 17a.

  The hub wheel 2 and the outer joint member 14 are coupled to each other until the stem portion 17 of the outer joint member 14 abuts the side surface of the caulking portion 6 with the shoulder portion 16 through a plate (cap) 18 described later. 2, with the caulking portion 6 and the shoulder portion 16 butting each other, the fixing nut 19 is fastened to the male screw 17 b with a predetermined tightening torque, and the hub wheel 2 and the outer joint member 14 are detachable in the axial direction. Is bound to.

  Here, as shown in an enlarged view in FIG. 2, the surface pressure applied to the crimping portion 6 by the axial force can be reduced, and plastic deformation and wear of the crimping portion 6 can be prevented. The end surface of the caulking portion 6 is formed as a flat surface. A cap 18 is interposed between the caulking portion 6 and the shoulder portion 16 of the outer joint member 14, and is fixed while being clamped between the caulking portion 6 and the shoulder portion 16. The cap 18 is formed by press working from an austenitic stainless steel plate (JIS standard SUS304 system or the like) having antirust performance. The material of the cap 18 is not limited to that illustrated, but may be a ferritic stainless steel plate (JIS standard SUS430 system or the like).

  The cap 18 is made of a disc-like plate having a contact portion 18a, and a low friction resin coating layer is formed on the contact portion 18a by painting. The low-friction resin coating layer is formed on the inner side surface of the contact portion 18a (the contact surface with the shoulder portion 16 of the outer joint member 14) and the outer side surface (the end surface 6a of the crimping portion 6). It may be formed on one of the side surfaces. Thus, by using the stainless steel plate which has a rust prevention ability as a raw material of the cap 18, the coating range of the low friction resin coating layer can be limited and cost reduction can be achieved. Note that the surface of the cap 18 is preliminarily shot blasted as a base of the low friction resin coating layer. Thereby, adhesiveness can be improved and it can prevent that a low friction resin film layer peels over a long period of time.

  The following can be illustrated as a low friction resin coating material which forms a low friction resin film layer. The low-friction resin coating contains 40-50% by weight of fluororesin, 45-55% by weight of matrix resin, and 1-10% by weight of graphite with respect to the coating film. The fluororesin can be used as long as it has low friction and can impart non-adhesiveness to the coating layer and has heat resistance that can withstand the operating temperature atmosphere of the sliding member.

Specific examples include polytetrafluoroethylene (melting point: 327 ° C., continuous use temperature: 260 ° C., hereinafter referred to as PTFE). This PTFE is composed of repeating units of —CF ₂ CF ₂ —, has a high melt viscosity of about 10 ¹⁰ to 10 ¹¹ Pa · s at about 340 to 380 ° C., and hardly flows even when the melting point is exceeded. Among them, it has the highest heat resistance. In addition, it exhibits excellent properties even at low temperatures and has excellent friction and wear characteristics, and is suitable for the low friction resin coating according to the present invention. PTFE is a powder and is not particularly limited. However, a powder having a particle size of 30 μm or less is preferred for the surface smoothness of the coating film.

  In the low friction resin coating, the matrix resin has heat resistance that does not cause thermal degradation when the cap 18 is used, and heat resistant resin that can adhere the fluororesin powder and firmly adhere the low friction resin coating to the cap 18. Can be used.

  Specifically, polyamideimide resin (PAI) can be exemplified. PAI is a resin having an imide bond and an amide bond in the molecule, and the imide bond of the aromatic polyamideimide resin may be a precursor such as polyamic acid or a closed imide ring. Furthermore, a state in which they are mixed may be used.

  Such aromatic PAIs include aromatic primary diamines such as diphenylmethane diamine and aromatic tribasic acid anhydrides such as PAI produced from mono- or dialsyl halide derivatives of trimellitic anhydride. PAI produced from an aromatic tribasic acid anhydride and an aromatic diisocyanate compound, for example, difermethane diisocyanate, and further, as PAI having a larger ratio of imide bonds than amide bonds, aromatic, aliphatic Alternatively, PAI produced from an alicyclic diisocyanate compound and an aromatic tetrabasic acid dianhydride and an aromatic tribasic acid anhydride can be used, and any PAI can be used.

  Further, either one or both of the shoulder portion 16 of the outer joint member 14 and the end surface 6a of the caulking portion 6 that are in contact with the surface formed by coating the low friction resin film layer of the cap 18 have a surface roughness of Ra 3.2 μm. Finished to be as follows. The shoulder portion 16 of the outer joint member 14 is not limited to the turning finish, and the surface hardness is set to a range of 50 to 64 HRC by induction hardening, and then the surface roughness is Ra 3.2 μm or less by grinding. You may form so that it may become. Further, the end surface 6a of the caulking portion 6 may be formed to Ra 3.2 [mu] m or less by restricting the surface roughness of the caulking jig for swing caulking. Ra here is one of the JIS roughness shape parameters (JIS B0601-2001), and means the arithmetic average roughness, that is, the average value of the absolute value deviation from the average line.

  Thus, in this embodiment, the low friction resin coating layer is formed on the contact portion 18a of the steel plate cap 18 sandwiched between the crimping portion 6 and the shoulder portion 16 of the outer joint member 14, Since the shoulder 16 of the outer joint member 14 and the end surface 6a of the crimped portion 6 are finished by finishing and the surface roughness is set to Ra 3.2 μm or less, deformation is caused by the axial force that fastens the constant velocity universal joint 13. This prevents wear during use and increases backlash between the caulking portion 6 and mitigates sudden slip that occurs between the caulking portion 6 and the shoulder 16 of the outer joint member 14. In addition, it is possible to provide a wheel bearing device that prevents the occurrence of stick-slip noise over a long period of time.

  The graph shown in FIG. 3 is a test result for evaluating the wear characteristics of the low friction resin coating layer implemented by the present applicant. The test was performed under three conditions where the contact surface pressure P was 45 MPa, 68 MPa, and 102 MPa. Here, the low friction resin coating layer is formed in the range of 10 to 30 μm. If the wear amount is 10 μm, the wear limit is set to Ra 3.26 μm or less as shown in this graph. It is necessary to. In other words, by setting the surface roughness of the counterpart material to Ra 3.26 μm or less, the low friction resin coating layer can be held for a long period of time, and abrupt slip generated on the contact surface can be alleviated. Can do. Here, if the thickness of the low-friction resin coating layer is less than 10 μm, the effect as a coating layer cannot be expected, and if it exceeds 30 μm, the bonding force to the contact portion 18a is lowered and warps unevenly. It is not preferable.

  FIG. 4 shows a modified example of the cap 18 described above and shows a state during assembly. The cap 20 is formed from a cold-rolled steel plate (JIS standard SPCC system, etc.) by press working so that the cross section is substantially L-shaped. The disc-shaped contact portion 20a and the inner diameter portion of the contact portion 20a A cylindrical fitting portion 20b extending in the axial direction is provided. The cap 20 is detachably fixed to the caulking portion 6 by press-fitting the fitting portion 20 b into the inner diameter of the caulking portion 6.

  Here, in the present embodiment, a low friction resin coating layer is formed by coating on the surface of the cap 20 that contacts the shoulder 16 of the outer joint member 14, and the shoulder 16 of the outer joint member 14 that contacts the cap 20. However, it is turned so that the surface roughness is Ra 3.2 μm or less. This prevents the cap 20 itself from rusting over a long period of time even when a stainless steel plate with good press workability and good rust prevention performance is used as the material of the cap 20, and the embodiment described above. Similarly to the above, the occurrence of stick-slip noise can be prevented. In this case, since the low friction resin coating layer is formed only on one side by painting, the painting operation is simplified and the cost can be reduced. In addition, as the material of the cap 20, a cold-rolled steel plate can be used to form a low friction resin coating layer on the entire surface by painting, and the material of the cap 20 can be made inexpensive.

  FIG. 5 shows another modification of the cap 18 described above. The cap 21 is formed from an austenitic stainless steel plate by pressing to have a substantially L-shaped cross section, and has a disk-like contact portion 21a and a cylindrical shape extending in the axial direction from the outer diameter portion of the contact portion 21a. And a locking portion 21c that protrudes radially inward from the flange 21b. The inner diameter of the locking portion 21c is set to be slightly smaller than the outer diameter of the crimping portion 6. The cap 21 is attached to the crimping portion 6 by elastically deforming the locking portion 21c.

  In addition, by forming a plurality of slits (not shown) extending in the axial direction at equal intervals in the circumferential direction of the flange portion 21b and the locking portion 21c as outer diameter portions, the cap 21 can be easily attached to the crimping portion 6 with one touch In addition to being able to be mounted, it is possible to prevent the cap 21 from falling off from the crimped portion 6 in the assembly process, and the number of assembly steps can be improved.

  FIG. 6 shows another modification of the cap 18 described above. The cap 22 has a substantially L-shaped cross section formed by pressing from a stainless steel plate, and has a disk-like contact portion 22a and a cylindrical fitting extending in the axial direction from the outer diameter portion of the contact portion 22a. A joint portion 22b is provided. A low friction resin coating layer is formed by painting on the surface of the cap 22 that contacts the shoulder portion 16 of the outer joint member 14, and the fitting portion 22 b is press-fitted into the outer diameter of the inner ring 3. The shoulder 16 of the outer joint member 14 that contacts the cap 22 is turned so that the surface roughness is Ra 3.2 μm or less. Thereby, intrusion of foreign matter such as rainwater and dust into the crimping portion 6 can be prevented, rusting of the crimping portion 6 can be prevented and durability can be improved, and the cap 22 can be used for a long period of time. Rusting can be prevented, and stick-slip noise can be prevented from occurring as in the above-described embodiment. In addition to this, a cold-rolled steel sheet may be used as the material of the cap 22 and the low friction resin coating layer may be formed on the entire surface by painting.

  FIG. 7 shows a modification of the cap 22 described above. The cap 23 has a substantially L-shaped cross section formed by pressing from a stainless steel plate, and has a disk-like contact portion 23a and a cylindrical fitting extending in the axial direction from the outer diameter portion of the contact portion 23a. A joint portion 23b is provided. Then, a low friction resin coating layer is formed on the surface of the cap 23 that contacts the end surface 6a of the crimping portion 6 by coating, and the end surface 6a of the crimping portion 6 that contacts the cap 23 has a surface roughness of Ra 3.2 μm or less. Finished to be. Thereby, it is possible to prevent the cap 23 from rusting over a long period of time, and it is possible to prevent the occurrence of stick-slip noise as in the embodiment described above. In addition to this, a cold-rolled steel sheet may be used as the material of the cap 23, and the low friction resin coating layer may be formed on the entire surface by painting.

  8 is a longitudinal sectional view showing a second embodiment of the wheel bearing device according to the present invention, FIG. 9 is an enlarged view of a main part showing the cap mounting portion of FIG. 8, and FIG. 10 is a view of the cap of FIG. FIG. 11 is an enlarged view of a main part showing a modification of the cap of FIG. 10, and FIG. 12 is an enlarged view of a main part showing a modification of the cap of FIG. This embodiment basically differs from the above-described embodiment only in the configuration of the hub wheel, and other parts having the same parts or the same functions are denoted by the same reference numerals and detailed description thereof is omitted. .

  This wheel bearing device is referred to as a third generation for driving wheels, and the inner member 25, the outer member 10, and the double row rolling elements 8, 8 accommodated between the members 25, 10 so as to roll freely. The constant velocity universal joint 13 is detachably coupled. The inner member 25 includes a hub ring 26 and the inner ring 3 press-fitted into the hub ring 26.

  The hub wheel 26 is made of medium-high carbon steel containing 0.40 to 0.80% by weight of carbon such as S53C, and integrally has a wheel mounting flange 4 at an outer end portion, and has one (outer side) outer periphery. An inner rolling surface 2a and a cylindrical small-diameter step 2b extending in the axial direction from the inner rolling surface 2a are formed, and a serration 2c for torque transmission is formed on the inner periphery.

  The stem portion 17 of the outer joint member 14 is fitted and inserted into the hub wheel 26 until the shoulder portion 16 abuts against the large end surface 3b of the inner ring 3 via the cap 18, and the inner ring 3 and the shoulder portion 16 are in contact with each other. The fixing nut 19 is fastened to the male screw 17b with a predetermined tightening torque, and the hub wheel 26 and the outer joint member 14 are detachably coupled in the axial direction.

  Here, the cap 18 is interposed between the large end surface 3 b of the inner ring 3 and the shoulder 16 of the outer joint member 14. The cap 18 is formed by press working from an austenitic stainless steel plate having rust prevention capability, and includes a disk-shaped contact portion 18a as shown in an enlarged view in FIG. A low friction resin coating layer is formed on at least the contact portion 18a of the cap 18 by painting. On the other hand, either or both of the shoulder 16 of the outer joint member 14 that contacts the surface formed by painting the low friction resin coating layer of the cap 18 and the large end surface 3b of the inner ring 3 have a surface roughness of Ra 3.2 μm. Finished to be as follows. Thereby, it can prevent that the cap 18 rusts over a long period of time, and can prevent generation | occurrence | production of a stick slip sound like embodiment mentioned above.

  FIG. 10 shows a modification of the cap 18 of FIG. The cap 27 is formed by pressing a stainless steel plate into a substantially L-shaped cross section, and has a disk-like contact portion 27a and a cylindrical fitting extending in the axial direction from the inner diameter portion of the contact portion 27a. A portion 27b is provided. And this fitting part 27b is fitted by the internal-diameter surface of the small diameter step part 2b. A low friction resin coating layer is formed on the surface of the outer joint 14 of the cap 27 that contacts the shoulder 16 by painting, and the outer ring joint member 14 that contacts the cap 27 has a surface roughness Ra3. Finished so as to be 2 μm or less. Thereby, it is possible to prevent the cap 27 from rusting for a long period of time, and to prevent the occurrence of stick-slip noise as in the above-described embodiment. In addition to this, a cold-rolled steel sheet may be used as the material of the cap 27, and the low friction resin coating layer may be formed on the entire surface by painting.

  FIG. 11 shows a modification of the cap 27 of FIG. The cap 28 is formed by pressing a stainless steel plate into a substantially L-shaped cross section, and has a disk-like contact portion 28a and a cylindrical fitting extending in the axial direction from the inner diameter portion of the contact portion 28a. A portion 28b is provided. The fitting portion 28 b is fitted to the inner diameter surface 3 c of the inner ring 3. A low friction resin coating layer is formed on the surface of the outer joint member 14 of the cap 28 that contacts the shoulder 16 by painting, and the shoulder 16 of the outer joint member 14 that contacts the cap 28 has a surface roughness Ra3. Finished to be 2 μm or less. Thereby, it is possible to prevent the cap 28 from rusting for a long period of time, and it is possible to prevent the occurrence of stick-slip noise as in the embodiment described above. In addition to this, a cold-rolled steel sheet may be used as the material of the cap 28, and the low friction resin coating layer may be formed on the entire surface by painting.

  FIG. 12 shows a modification of the cap 28 of FIG. The cap 29 is formed by pressing a stainless steel plate into a substantially L-shaped cross section. The cap 29 has a disk-like contact portion 29a and a cylindrical fitting extending in the axial direction from the outer diameter portion of the contact portion 29a. A joint portion 29b is provided. The fitting portion 29 b is fitted to the shoulder portion 16 of the outer joint member 14. The surface of the cap 29 that contacts the large end surface 3b of the inner ring 3 is coated with a low-friction resin coating layer, and the large end surface 3b of the inner ring 3 that contacts the cap 29 has a surface roughness Ra of 3.2 μm or less. Has been processed. Thereby, it is possible to prevent the cap 29 from rusting over a long period of time, and to prevent the occurrence of stick-slip noise as in the embodiment described above. In addition to this, a cold-rolled steel sheet may be used as the material of the cap 29, and the low friction resin coating layer may be formed on the entire surface by painting.

  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.

  A wheel bearing device according to the present invention includes an inner member composed of a hub wheel and an inner ring, and a constant velocity universal joint, and the inner member and the outer joint member of the constant velocity universal joint are detachably fastened in a butted state. Further, the present invention can be applied to wheel bearing devices having first to third generation structures.

1, 25 Inner member 2, 26 Hub wheel 2a, 3a Inner rolling surface 2b Small diameter step 2c, 17a Serration 3 Inner ring 3b Large end surface 3c of inner ring 4 Inner ring inner diameter surface 4 Wheel mounting flange 5 Hub bolt 6 Caulking portion 6a Addition End surface 7 of the fastening portion Inner side base 8 of the wheel mounting flange Rolling body 9 Cage 10 Outer member 10a Outer rolling surface 10b Car body mounting flange 11 Outer side seal 12 Inner side seal 13 Constant velocity universal joint 14 Outer joint Member 15 Mouse part 16 Shoulder part 17 Stem part 17b Male thread 18, 20, 21, 22, 23, 27, 28, 29 Cap 18a, 20a, 21a, 22a, 23a, 27a, 28a, 29a Contact part 19 Fixing nut 20b , 22b, 23b, 27b, 28b, 29b Fitting portion 21b Ridge portion 21c Locking portion 50 Wheel bearing device 51 Outer member 51 a Outer rolling surface 51b Car body mounting flange 52 Hub wheels 52a and 53a Inner rolling surface 52b Small diameter step portion 53 Inner ring 54 Wheel mounting flange 55 Inner member 56 Cage 57 Ball 58, 59 Seal 60 Caulking portion 61 Constant velocity freely Joint 62 Outer joint member 63 Shoulder part 64 Stem part 64a Serration 65 Fixing nut 66 Cap 66a Contact part 66b Fitting part 66c Gutter part

Claims (14)

An outer member in which a double row outer rolling surface is integrally formed on the inner periphery;
A hub wheel integrally having a wheel mounting flange for mounting a wheel at one end, a cylindrical small-diameter stepped portion extending in the axial direction on the outer periphery, and a serration formed on the inner periphery, and a small diameter of the hub wheel An inner member formed of at least one inner ring press-fitted into a stepped portion and formed with a double-row inner rolling surface facing the double-row outer rolling surface;
Formed between the outer member and the inner member, and a double row rolling element accommodated between the rolling surfaces of the inner member and the outer member via a cage. A seal mounted on both side openings of the annular space,
A constant velocity universal joint is connected to the hub wheel,
The outer joint member of the constant velocity universal joint has a cup-shaped mouth portion, a shoulder portion that forms the bottom of the mouth portion, and extends axially from the shoulder portion so that torque can be transmitted to the hub wheel via serrations. It has a stem part that fits inside,
In the wheel bearing device in which the shoulder portion is in contact with the inner member, and the hub wheel and the outer joint member are detachably coupled in the axial direction via a fixing nut,
A steel plate cap provided with a disk-shaped contact portion is interposed between the end surface of the inner member and the shoulder portion of the outer joint member. A low-friction resin coating layer is formed on at least one of the surfaces by painting, and the surface roughness of the shoulder portion of the outer joint member that contacts the cap and the end surface of the inner member is set to Ra 3.2 μm or less. A bearing device for a wheel, characterized in that   2. The wheel bearing device according to claim 1, wherein the low-friction resin coating layer is blended with 40 to 50 wt% fluororesin, 45 to 55 wt% matrix resin, and 1 to 10 wt% graphite.   The wheel bearing device according to claim 1 or 2, wherein the surface of the cap is preliminarily shot blasted as a base of the low friction resin coating layer.   The inner ring is fixed in the axial direction by a caulking portion formed by plastically deforming an end portion of the small-diameter step portion of the hub wheel radially outward, and an end surface of the caulking portion is formed as a flat surface. The wheel bearing device according to claim 1, wherein the cap is sandwiched between an end surface of the caulking portion and a shoulder portion of the outer joint member.   The wheel according to claim 4, wherein the cap includes a cylindrical fitting portion extending in an axial direction from an inner diameter portion of the contact portion, and the fitting portion is fitted to an inner diameter surface of the caulking portion. Bearing device.   The cap includes a cylindrical flange extending in the axial direction from an outer diameter portion of the contact portion, and a locking portion protruding radially inward from the flange, and the inner diameter of the locking portion is The wheel bearing device according to claim 4, wherein the wheel bearing device is set to be slightly smaller than the outer diameter of the caulking portion, and the cap is attached to the caulking portion by elastically deforming the locking portion.   The wheel bearing device according to claim 6, wherein a plurality of slits extending in the axial direction are formed at equal intervals in the circumferential direction of the flange portion and the locking portion of the cap.   The cap is interposed between the large end surface of the inner ring and the shoulder of the outer joint member, and the cap extends in the axial direction from the inner diameter portion of the contact portion. The wheel bearing device according to claim 1, wherein the fitting portion is fitted to the inner diameter surface of the small diameter stepped portion or the inner ring.   The said cap is provided with the cylindrical fitting part extended in the axial direction from the outer-diameter part of the said contact part, This fitting part is fitted by the outer diameter of the said inner ring | wheel. Wheel bearing device.   The said cap is provided with the cylindrical fitting part extended in the axial direction from the outer-diameter part of the said contact part, This fitting part is fitted to the shoulder part of the said outer joint member. Wheel bearing device.   The wheel bearing device according to any one of claims 1 to 10, wherein a material of the cap is formed by press working from a stainless steel plate having rust prevention ability, and the low friction resin coating layer is formed at the contact portion.   The wheel bearing device according to any one of claims 1 to 10, wherein a material of the cap is formed from a cold-rolled steel plate by press working, and the low friction resin coating layer is formed on the entire surface of the cap.   2. The wheel bearing device according to claim 1, wherein the shoulder portion of the outer joint member is subjected to a hardening process in a range of 50 to 64 HRC by induction hardening and then ground. 3.   The wheel bearing device according to claim 4, wherein an end surface of the caulking portion is turned after swing caulking.

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