JP4436386B2 - Wheel bearing and wheel bearing device including the same - Google Patents

Description

The present invention relates to a wheel bearing device for supporting a drive wheel of a vehicle such as an automobile, and more particularly, to a drive wheel (an FF vehicle front wheel, an FR vehicle or an RR vehicle rear wheel, and a 4WD vehicle) mounted on an independent suspension. The present invention relates to a wheel bearing that rotatably supports a suspension device and a wheel bearing device including the same.

  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. 4 are known. The wheel bearing device 50 is connected to a hub wheel 51 on which one end of the wheel W and the brake rotor B is mounted, a double-row rolling bearing 52 that rotatably supports the hub wheel 51, and the hub wheel 51. A fixed type constant velocity universal joint 53 that transmits power of a drive shaft (not shown) to the hub wheel 51 is provided.

  The hub wheel 51 integrally has a wheel mounting flange 54 for mounting the wheel W and the brake rotor B at one end portion, and a cylindrical small-diameter step portion 51 a extending in the axial direction from the wheel mounting flange 54 is formed. .

  The double-row rolling bearing 52 is mounted between the knuckle N constituting the suspension device and the small-diameter step portion 51a of the hub wheel 51, and an outer ring 55 in which double-row outer rolling surfaces 55a and 55a are formed on the inner periphery, A pair of inner rings 56, 56 each having an inner rolling surface 56 a opposite to the outer circumferential rolling surfaces 55 a, 55 a in a double row on the outer periphery, and a cage 57 between both rolling surfaces 55 a, 56 a are freely rollable. And a double-row angular ball bearing having double-row balls 58 and 58 accommodated in the ball.

  The constant velocity universal joint 53 is an outer joint member integrally having a cup-shaped mouth portion (not shown), a shoulder portion 59 that forms the bottom portion of the mouth portion, and a shaft portion 60 that extends in the axial direction from the shoulder portion 59. 61 is provided. The outer joint member 61 is fitted into the hub wheel 51 through serrations so as to transmit torque. Then, the shaft portion 60 is fitted into the hub wheel 51 until the shoulder portion 59 abuts against the inner ring 56 of the double row rolling bearing 52, and the fixing nut 63 is attached to the male screw 62 formed at the end of the shaft portion 60. Are fastened with a predetermined tightening torque, and the hub wheel 51 and the outer joint member 61 are coupled so as to be separable in the axial direction.

  A large torque is applied to the wheel W of such a vehicle from the engine via a sliding type constant velocity universal joint (not shown) when the engine rotates at a low speed, for example, when the vehicle starts, and the drive shaft may be twisted. Are known. As a result, the inner ring 56 of the double row rolling bearing 52 supporting the drive shaft is also twisted. Thus, when a large twist occurs in the drive shaft, a so-called stick-slip noise is generated due to a sudden slip at the contact surface between the outer joint member 61 and the inner ring 56.

As a countermeasure against this, in the conventional wheel bearing device 50, a surface treatment for reducing the frictional resistance is applied to a portion of the outer joint member 61 that contacts the shoulder 59. Specifically, as shown in FIGS. 5A and 5B, grease grooves 64 are formed in the circumferential direction on the end faces 56 b and 56 c of the inner ring 56. With this surface treatment, lubricating oil such as grease can easily enter between the abutting member and the frictional resistance can be reduced, and smooth slipping can be obtained and the effect of suppressing stick-slip noise can be exhibited.
JP 2000-110840 A

  However, in this conventional wheel bearing device, the end surfaces 56b and 56c of the inner ring 56 are subjected to a surface treatment including the grease grooves 64, thereby reducing the frictional resistance with the abutting member and suppressing the stick-slip noise. However, it is necessary to perform such a surface treatment on a plurality of parts, which increases the number of processing steps and complicated the process management, which is a factor that hinders cost reduction.

  Further, in this type of wheel bearing device, a fixing nut 63 is screwed onto the male screw 62 of the shaft portion 60 of the outer joint member 61, and a double row rolling bearing 52 is formed by tightening force (axial force) of the fixing nut 63. Because the amount of preload is adjusted and managed, a certain level of tightening force is required. In this case, a lubricant such as grease can be applied to the contact surface at the beginning to reduce the coefficient of friction, but the applied grease may flow out to the outside due to the tightening force, and its effect over a long period of time. It is difficult to sustain.

The present invention has been made in view of such circumstances, and provides a wheel bearing that prevents the occurrence of stick-slip noise by realizing smooth sliding with an abutting member, and a wheel bearing device including the same. The purpose is to provide.

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 attachment for attaching a wheel to one end. An outer joint member of a constant velocity universal joint that is press-fitted into a small-diameter step portion of a hub ring integrally having a flange, is fitted into the hub ring so as to be able to transmit torque, and is coupled to be separable in an axial direction via a fixing nut. A pair of inner rings, which are in abutting contact with the shoulders of the inner ring and formed with an inner rolling surface facing the outer rolling surface of the double row on the outer periphery, and are rotatably accommodated between the two rolling surfaces. in the wheel support bearing and a rolling element of the double row has, by Rukoto lapping is performed on the large end face of the inner ring into contact with the shoulder portion, the area of the mirror surface portion of the large end face is reduced, fine The streak increases, the friction coefficient decreases, and the contact surface slides smoothly. To be able to, the occurrence of stick-slip noise can be prevented.

As described above, the constant velocity universal joint that is press-fitted into the outer member and the small-diameter step portion of the hub wheel, is internally fitted to the hub wheel so as to be able to transmit torque, and is detachably coupled in the axial direction via the fixing nut. A pair of inner races that are in contact with the shoulders of the outer joint member in abutment and have inner rolling surfaces that are opposed to the double row outer rolling surfaces on the outer periphery, and a plurality of rolling elements accommodated between the two members in the wheel support bearing assembly equipped and in which, Rukoto lapping is performed on the large end face of the inner ring in contact with the shoulder portion, the area of the mirror portion of the large end face is reduced, fine streaky marks increases, It is possible to provide a wheel bearing in which a smooth slip with a mating member having a reduced friction coefficient can be absorbed and a stick-slip noise is prevented from occurring for a long period of time.

Further, as in the invention described in claim 2, the outer member in which the double-row outer rolling surface is integrally formed on the inner periphery and the wheel mounting flange for mounting the wheel on one end are integrally provided. And a hub wheel having a cylindrical small-diameter step portion extending in the axial direction on the outer periphery, and press-fitted into the small-diameter step portion of the hub wheel, and is fitted into the hub wheel so as to be able to transmit torque, and is fixed to the shaft via a fixing nut. The inner row of the double row, which is composed of at least one inner ring that is in contact with the shoulder of the outer joint member of the constant velocity universal joint that is separably coupled in the direction, and that faces the outer rolling surface of the double row In a wheel bearing device comprising an inner member formed with a rolling surface and a double row rolling element that is slidably accommodated between the both rolling surfaces, the inner ring contacting the shoulder portion the Rukoto lapping is performed on the large end face, the area of the mirror surface portion of the large end face Reduced, and fine streaky marks increases, the friction coefficient becomes small contact surface can be slid smoothly, it may be a wheel bearing device occurrence of stick-slip noise is prevented.

Further, as in the invention described in claim 3 , if the shoulder portion of the outer joint member is ground or turned, and concentric cuts are formed on the contact surface with the large end surface of the inner ring. In addition, it is possible to prevent the occurrence of stick-slip noise by preventing the surface from being caught by unevenness.

Further, when the surface roughness of the large end surface is regulated to Ra 0.7 or less as in the invention described in claim 4 , the surface is prevented from being caught by unevenness, and the occurrence of stick-slip noise is surely prevented. can do.

Further, as in the invention described in claim 5, the outer joint member integrally has a shaft portion extending in the axial direction from the shoulder portion, and a serration is formed on an outer periphery of the shaft portion. with a predetermined angle inclined twist angle provided we are for, when the outer joint member via the serrations long as internally fitted to the hub wheel, preload is applied to the fitting portion of the serration, the drive shaft Even when large torsion occurs, a sudden slip does not occur on the contact surface between the inner ring and the outer joint member, and stick-slip noise can be further prevented.

A wheel bearing according to the present invention is a hub wheel small-diameter step having an outer member integrally formed with an outer periphery of a double row on the inner periphery and a wheel mounting flange for mounting a wheel at one end. And is abutted against the shoulder of the outer joint member of the constant velocity universal joint that is fitted into the hub wheel so as to transmit torque and is separable in the axial direction via a fixing nut. A pair of inner rings having an inner rolling surface facing the outer rolling surface of the double row on the outer periphery, and a double row rolling element accommodated so as to roll between the rolling surfaces. in the wheel bearing, the Rukoto lapping is performed on the large end face of the inner ring into contact with the shoulder portion, the area of the mirror portion of the large end face is reduced, fine streaky marks increases, the friction coefficient that is to moor a smooth sliding of the abutting mating member is small Come, it is possible to provide a wheel bearing which prevents the occurrence of stick-slip noise for a long period of time.

  A hub wheel integrally having a wheel mounting flange for mounting a wheel at one end and having a cylindrical small-diameter step portion extending in the axial direction on the outer periphery via a shoulder portion, and a small-diameter step portion of the hub ring A wheel bearing that is press-fitted through a predetermined shimoshiro, and a constant velocity universal joint that is fitted into the hub wheel so as to be able to transmit torque and that is separably coupled in an axial direction through a fixing nut. A bearing for the outer member in which a double row outer rolling surface is integrally formed on the inner periphery, and a pair of inner rings in which an inner rolling surface facing the outer rolling surface of the double row is formed on the outer periphery; And a double row rolling element housed between the rolling surfaces so as to be freely rollable, and a shoulder portion of the outer joint member of the constant velocity universal joint is brought into contact with the large end face of the inner ring in abutting state. In the wheel bearing device, the shoulder of the outer joint member and the large end surface of the inner ring are sharpened. While being processed, the large end face is lapping after grinding, the surface roughness is regulated to Ra0.7 or less.

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 an enlarged view of a main part of FIG. 1, and FIG. 3 is a graph showing friction coefficients and surface roughness of a large end face of an inner ring. It is a graph which shows a relationship. In the following description, the side closer to the outer side of the vehicle in a state assembled to the vehicle is referred to as the outer side (left side in the drawing), and the side closer to the center is referred to as the inner side (right side in the drawing).

  This wheel bearing device is connected to a hub wheel 1 for mounting a wheel W and a brake rotor B at one end, a wheel bearing 2 for rotatably supporting the hub wheel 1, and a hub wheel 1, and a drive shaft ( A fixed type constant velocity universal joint 3 for transmitting the power of (not shown) to the hub wheel 1 is provided.

  The hub wheel 1 integrally has a wheel mounting flange 4 for mounting the wheel W and the brake rotor B at an end on the outer side, and a cylinder extending in the axial direction from the wheel mounting flange 4 to the outer periphery via a shoulder 1a. A small diameter step portion 1b is formed, and a serration (or spline) 1c for torque transmission is formed on the inner periphery. In addition, hub bolts 4a for fastening the wheel W and the brake rotor B are planted in the wheel mounting flange 4 at equal intervals in the circumferential direction.

  The wheel bearing 2 is mounted between the knuckle N constituting the suspension device and the small-diameter step portion 1b of the hub wheel 1, and an outer member (outer ring) in which double row outer rolling surfaces 5a and 5a are formed on the inner periphery. 5 and a pair of inner races 6, 6 formed on the outer periphery with inner rolling surfaces 6 a facing the double row outer rolling surfaces 5 a, 5 a, and a cage 7 between both rolling surfaces 5 a, 6 a. It has double-row rolling elements (balls) 8 and 8 accommodated so as to roll freely. The wheel bearing 2 has a so-called back-to-back type composite, in which the outer inner ring 6 abuts against the shoulder 1a of the hub wheel 1 and the small end surfaces of the pair of inner rings 6 and 6 abut each other in a butted state. It constitutes a row angular contact ball bearing. Further, seals 14 and 15 are attached to both ends of the outer member 5 to prevent leakage of lubricating grease sealed inside the bearing and intrusion of rainwater and dust from the outside into the bearing. .

  The constant velocity universal joint 3 includes an outer joint member 11 integrally including a shoulder portion 9 that forms the bottom of a cup-shaped mouth portion (not shown) and a shaft portion 10 that extends from the shoulder portion 9 in the axial direction. Yes. A serration (or spline) 10 a that is engaged with the serration 1 c of the hub wheel 1 is formed on the outer periphery of the shaft portion 10. The serration 10a is provided with a twist angle inclined by a predetermined angle with respect to the axis, and the shaft portion 10 is fitted into the hub wheel 1 until the shoulder portion 9 of the outer joint member 11 contacts the inner ring 6 on the inner side. The hub wheel 1 is press-fitted into the serration 1c. Then, the shaft portion 10 is fitted into the hub wheel 1 until the shoulder portion 9 is brought into contact with the inner ring 6 on the inner side of the wheel bearing 2, and a fixing nut is attached to the male screw 12 formed at the end portion of the shaft portion 10. The hub wheel 1 and the outer joint member 11 are coupled so as to be separable in the axial direction in a state where 13 is tightened with a predetermined tightening torque and a predetermined preload is applied to the wheel bearing 2. Thus, since preload is applied to the fitting portions of the serrations 1c and 10a and the play in the circumferential direction is killed, even if a large twist occurs in the drive shaft, the large end surface 6b of the inner ring 6 on the inner side Abrupt slip is unlikely to occur on the contact surface of the outer joint member 11 with the shoulder 9, and the rigidity and durability of the bearing can be improved.

  The hub wheel 1 is formed of medium and high carbon steel containing 0.40 to 0.80 wt% of carbon such as S53C, and the surface hardness is set to a range of 58 to 64 HRC by induction hardening from the shoulder portion 1a to the small diameter step portion 1b. It has been cured. Thereby, while having sufficient mechanical strength with respect to the rotational bending load applied to the wheel mounting flange 4, the fretting resistance of the small diameter step portion 1b is improved, and the durability of the hub wheel 1 is further improved. The outer member 5, the inner ring 3 and the rolling element 8 are made of a 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. The outer joint member 11 is made of medium-high carbon steel containing 0.40 to 0.80 wt% of carbon such as S53C, and has a surface hardness of 58 to 58 by induction hardening from the shoulder portion 9 to the base portion of the shaft portion 10. Hardened to a range of 64 HRC.

  The shoulder 9 of the outer joint member 11 and the large end surface 6b of the inner ring 6 are formed by grinding. Here, the stick-slip noise is considered to be caused by discontinuous slip between the shoulder portion 9 of the outer joint member 11 and the large end surface 6b of the inner ring 6 on the inner side. Generation of stick-slip noise can be suppressed by smoothly sliding the contact surfaces. For example, the large end surface 6b of the inner ring 6 on the inner side that has been ground is composed of a large number of streak-like traces extending in an irregular direction and a smooth mirror surface portion when the surface is observed with a microscope. In order to smoothly slide the contact surface, the present applicant pays attention to the finished surface state of the large end surface 6b of the inner ring 6 on the inner side, and the mirror surface portion of the large end surface 6b is related to the occurrence of stick-slip noise. It turns out that there is. That is, the surface of the large end surface 6b of the inner ring 6 on the inner side subjected to width grinding has many mirror surface portions, and the mirror surface portion further increases by improving the surface roughness. As a result of the on-table torsion test conducted by the above-mentioned, it is easy to adhere to the contact surface of the shoulder portion 9 of the ground outer joint member 11, and a stick-slip sound is generated when the contact surface is released from this adhesion. I found out.

  FIG. 3 is a graph showing the relationship between the area of the mirror surface of the large end surface 6b of the inner ring 6 on the inner side and the friction coefficient. As can be seen from this figure, it is composed of streak marks and a smooth mirror surface. In the large end surface 6b of the inner ring 6 on the inner side, the friction coefficient increases rapidly as the mirror surface area increases. Therefore, in this embodiment, lapping is performed after grinding the large end surface 6b of the inner ring 6 on the inner side. By this lapping, the mirror surface portion of the large end surface 6b is reduced and, on the contrary, fine streak marks are increased, so that the friction coefficient is reduced and the contact surface is smoothly slid to prevent the occurrence of stick-slip noise. Can do.

  Here, the lapping process is performed after the grinding process. However, the present invention is not limited thereto, and the lapping process may be performed after the heat treatment of the inner ring 6. However, if the surface roughness of the large end face 6b becomes worse than Ra0.7, it is caught by surface irregularities and a stick-slip sound is generated. Therefore, it is preferable to suppress the surface roughness to Ra0.7. Ra is one of the JIS roughness shape parameters (JIS B0601-1994), and means the arithmetic average roughness, that is, the average value of the absolute value deviation from the average line.

  Thus, when the shoulder portion 9 of the outer joint member 11 is a ground surface, since at least the large end surface 6b of the inner ring 6 on the inner side is lapped, the mirror surface portion is reduced and fine streak marks are formed. As a result, the coefficient of friction increases, the contact surface can be smoothly slid, and stick-slip noise can be prevented. When the shoulder portion 9 of the outer joint member 11 is ground, it is preferable that the contact surface with the large end surface 6b of the inner ring 6 on the inner side and the outer peripheral surface are simultaneously ground. As a result, concentric grinding marks are formed on the contact surface of the inner ring 6 on the inner side with the large end surface 6b, and it is possible to prevent the occurrence of stick-slip noise by preventing the surface from being caught.

  In addition, although the double row angular contact ball bearing which used the rolling element 8 as the ball | bowl was illustrated here, it is not restricted to this, The double row tapered roller bearing which uses a tapered roller for a rolling element may be sufficient. In addition, here, the wheel bearing device of the first generation structure is illustrated, but not limited to this, the outer joint member of the constant velocity universal joint is connected to the wheel bearing device, and the fixing nut is fastened to the outer joint member. By doing so, it can be applied to the first to third generation structures for applying the preload of the bearing.

  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 a hub ring and an inner ring press-fitted into the hub ring, and an outer joint member is fitted in the inner ring in abutment state, and the fixing nut is fastened to the outer joint member. It can be applied to a wheel bearing device in which the inner ring is fixed by the tightening force.

It is a longitudinal section showing one embodiment of a wheel bearing device concerning the present invention. It is a principal part enlarged view of FIG. It is a graph which shows the relationship between the mirror surface area of the large end surface of the inner ring | wheel which concerns on this invention, and a friction coefficient. It is a longitudinal cross-sectional view which shows the conventional wheel bearing apparatus. (A) is a fragmentary perspective view which shows the inner ring single-piece | unit of FIG. (B) is a partial perspective view showing a single inner ring as in the above.

Explanation of symbols

1. Hub wheel 1a, 9 ... Shoulder 1b ... Small diameter step 1c, 10a ... Serration 2 ... Wheel bearing 3 ... Constant velocity universal joint 4 ... Wheel mounting flange 4a ...・ ・ ・ ・ ・ ・ ・ ・ Hub bolt 5 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Outer member 5a ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Outer rolling surface 6 ・ ・ ・ ・ ・ ・ ・ ・・ Inner ring 6a ・ ・ ・ ・ ・ ・ Inner rolling surface 6b ・ ・ ・ ・ ・ ・ Large end surface 7 ・ ・ ・ ・ ・ ・ Cage 8・ ・ ・ ・ ・ ・ Rolling element 10 ・ ・ ・ ・ ・ ・ Shaft 11 ・ ・ ・ ・ ・ ・ Outer joint member 12 ・ ・ ・ ・ ・ ・ Male thread 13 ............ Fixing nuts 14, 15...・ Wheel bearing device 51... Hub wheel 51a... ... Constant velocity universal joint 54 ... Wheel mounting flange 55 ... Outer member 55a ... Outer rolling surface 56 ... Inner ring 56a ... Inner rolling surface 56b, 56c ... End face 57 ... Cage 58 ... Ball 59 ... Shoulder 60 ... Shaft 61 ... -Outer joint member 62 ... Male thread 63 ... Fixing nut 64 ... Grease groove B ... .... Brake rotor N ... Kuru W ··········· wheel

Claims (5)

An outer member in which a double row outer rolling surface is integrally formed on the inner periphery;
It is press-fitted into a small-diameter step portion of a hub wheel integrally having a wheel mounting flange for mounting a wheel at one end, and is fitted into the hub wheel so as to be able to transmit torque, and is coupled to be separable in the axial direction via a fixing nut. A pair of inner rings, which are in contact with the shoulders of the outer joint member of the constant velocity universal joint, in contact with each other, and formed with an inner rolling surface facing the outer rolling surface of the double row on the outer periphery;
In a wheel bearing comprising a double-row rolling element accommodated between the rolling surfaces so as to roll freely,
The Rukoto lapping is performed on the large end face of the inner ring into contact with the shoulder portion, the area of the mirror portion of the large end face is reduced, fine streaky marks is increased, those in the coefficient of friction is reduced A wheel bearing characterized in that a contact surface can be smoothly slid and stick-slip noise is prevented . 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 thereof and having a cylindrical small diameter step portion extending in the axial direction on the outer periphery, and the hub wheel press-fitted into the small diameter step portion of the hub wheel, Comprising at least one inner ring that is in contact with the shoulder of the outer joint member of the constant velocity universal joint that is fitted into the ring so as to be able to transmit torque and is axially separable through a fixing nut, An inner member in which a double row inner rolling surface facing the double row outer rolling surface is formed;
In the wheel bearing device comprising a double-row rolling element accommodated between the rolling surfaces so as to roll freely,
The Rukoto lapping is performed on the large end face of the inner ring into contact with the shoulder portion, the area of the mirror portion of the large end face is reduced, fine streaky marks is increased, those in the coefficient of friction is reduced A wheel bearing device characterized in that a contact surface can be smoothly slid and generation of stick-slip noise is prevented .   The wheel bearing device according to claim 2, wherein a shoulder portion of the outer joint member is ground or turned, and concentric cuts are formed on a contact surface with the large end surface of the inner ring.   The wheel bearing device according to claim 2 or 3, wherein a surface roughness of the large end surface of the inner ring is regulated to Ra 0.7 or less. The outer joint member integrally has a shaft portion extending in the axial direction from the shoulder portion, a serration is formed on the outer periphery of the shaft portion, and a torsion angle inclined by a predetermined angle with respect to the axis is provided on the serration. The wheel bearing device according to any one of claims 2 to 4, wherein the outer joint member is fitted into the hub wheel via the serration.

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