JP2011106600A - Bearing device for wheel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bearing device for a wheel, achieving high load capacity to elongate a service life of a bearing, and reducing a weight and a size thereof. <P>SOLUTION: The bearing device for a wheel includes a four-row angular ball bearing of a back-to-back type, in which four ball rows are housed to be capable of rolling between rolling surfaces of an internal member 1 and an external member 2, through retainers 7, 8. In this case, rows of balls 3a outside of a bearing center CL out of four rows of balls 3a, 3b, 3a, 3b have a pitch diameter DPa set to be larger than a pitch diameter DPb of rows of balls 3b of the inside. A ball diameter Da of the outer rows of balls 3a is set to be larger than a ball diameter Db of the inner rows of balls 3b, the balls 3b of the inner rows of the balls 3b are arranged at the center between ball pitches of the outer rows of the balls 3a, and a pitch P between the ball rows is set to be smaller than a sum of radii of balls (P≤(Da+Db)/2). <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a wheel bearing device that rotatably supports a wheel of an automobile or the like, and more particularly, to a wheel bearing device that achieves light weight and compactness and increases rigidity to extend the life of the bearing.

  2. Description of the Related Art Conventionally, a wheel bearing device for supporting a wheel of an automobile or the like is rotatably supported via a hub wheel for mounting the wheel, and there are a drive wheel and a driven wheel. For structural reasons, an inner ring rotation method is generally used for driving wheels, and an inner ring rotation method and an outer ring rotation method are generally used for driven wheels. As the wheel bearing device, a double-row angular ball bearing having a desired bearing rigidity, exhibiting durability against misalignment, and having a small rotational torque from the viewpoint of improving fuel efficiency is often used. In this double row angular contact ball bearing, a plurality of balls are interposed between a fixed ring and a rotating ring, and a predetermined contact angle is given to the balls so as to contact the fixed ring and the rotating ring.

  Further, the wheel bearing device has a structure called a first generation in which a wheel bearing composed of a double row angular ball bearing or the like is fitted between a knuckle and a hub wheel constituting a suspension device. Second generation structure in which body mounting flange or wheel mounting flange is formed directly on the outer periphery of the member, third generation structure in which one inner rolling surface is directly formed on the outer periphery of the hub wheel, or hub wheel, etc. It is roughly classified into a fourth generation structure in which the inner rolling surface is directly formed on the outer periphery of the outer joint member of the speed universal joint.

  Such a wheel bearing device is required to have a function of supporting the vehicle weight. For example, in a large vehicle such as a pickup truck or an SUV (Sport Utility Vehicle sport utility vehicle), a larger vehicle weight is loaded on the bearing. It is necessary to increase the load capacity itself. In this case, a double-row tapered roller bearing that uses a tapered roller instead of a ball as a rolling element is generally adopted. However, the double-row tapered roller bearing has a bearing clearance setting and installation error. When misalignment occurs, it is difficult to handle such as countermeasures for edge load generated between the tapered roller and the rolling surface against moment load. In recent years, rotational torque has been increased from the viewpoint of improving fuel efficiency. It becomes a fatal disadvantage. As a wheel bearing device that solves these problems, the one shown in FIG. 6 is known.

  This wheel bearing device integrally has a vehicle body mounting flange 51c to be attached to a knuckle (not shown) on the outer periphery, and four rows of outer rolling surfaces 51a, 51b, 51a, 51b are formed on the inner periphery. The outer member 51 and a wheel mounting flange 53 for attaching a wheel (not shown) to one end are integrally formed, and a small-diameter step portion 52a extending in the axial direction from the wheel mounting flange 53 is formed on the outer periphery. A hub wheel 52 and a double-row inner rolling surface 54a, 54b facing the outer rolling surfaces 51a, 51b, 51a, 51b of four rows are formed by being fitted on the hub wheel 52 and the small-diameter step portion 52a of the hub wheel 52. An inner member 55 composed of a pair of inner rings 54, 54, four rows of balls 56a, 56b, 56a, 56b accommodated between these rolling surfaces, and rolling these balls 56a, 56b, 56a, 56b freely It is composed of four columns angular ball bearing of which includes a retainer 57, 58 for holding.

  The pair of inner rings 54, 54 are fixed in the axial direction by a caulking portion 52 b formed by plastically deforming the end portion of the small diameter step portion 52 a of the hub wheel 52 radially outward. Seals 59 and 60 are attached to the opening of the annular space formed between the outer member 51 and the inner member 55, leakage of the lubricating grease sealed inside the bearing, and rainwater entering the bearing from the outside. And dust are prevented from entering.

  Here, two rows of bearing rows have first pitch circle diameters TK1, TK4, and the other two rows of bearing rows have second pitch circle diameters TK2, TK3 different from the first pitch circle diameters TK1, TK4. Bearing rows each having the same pitch circle diameter are provided symmetrically with respect to the plane ME perpendicular to the axial direction of the bearing. As a result, the load capacity of the bearing can be increased, and a desired bearing life can be ensured even if a larger vehicle weight is loaded on the bearing (see, for example, Patent Document 1).

Special table 2009-525447 gazette

  However, in such a conventional wheel bearing device, although it is possible to increase the load capacity of the bearing, there is a problem in that by making the bearing row four rows, the axial width becomes wider and the weight and size of the device are hindered. was there.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a wheel bearing device that achieves a longer load life by increasing the load capacity and that is lighter and more compact. It is said.

  In order to achieve such an object, the invention according to claim 1 of the present invention includes an outer member in which four rows of outer rolling surfaces are integrally formed on the inner periphery, and a wheel mounting flange for mounting the wheel at one end. A hub wheel having a small-diameter step portion extending in the axial direction on the outer periphery, and at least one inner ring press-fitted into the small-diameter step portion of the hub wheel, and the four rows of outer rolling surfaces on the outer periphery. 4 rows of inner members in which four rows of inner rolling surfaces facing each other are formed, and four rows of the inner members and the outer members that are accommodated between the rolling surfaces of the inner member and the outer members via a cage. A wheel bearing device comprising a back-to-back type four-row angular ball bearing, wherein the pitch circle diameter of an outer ball row with respect to the center of the bearing is an inner ball. The outer diameter of the outer circle is set to be larger than the pitch circle diameter of the row. The ball diameter of the row is set to be larger than the ball diameter of the inner ball row, the balls of the inner ball row are arranged between the ball pitches of the outer ball row, and the outer ball row and the inner ball row are arranged. The pitch between the ball rows is set smaller than the sum of the radii of the balls.

  As described above, the four rows of ball rows are provided between the rolling surfaces of the inner member and the outer member so as to be freely rollable via the cage, and are constituted by back-to-back type four row angular ball bearings. In the above-described wheel bearing device, the pitch circle diameter of the outer ball row with respect to the bearing center of the four ball rows is set larger than the pitch circle diameter of the inner ball row, and the outer ball row. The ball diameter of the inner ball row is set to be larger than the ball diameter of the inner ball row, the balls of the inner ball row are arranged between the ball pitches of the outer ball row, and the outer ball row and the inner ball row are arranged. Since the pitch between the balls is set smaller than the sum of the radii of the balls, a wheel bearing device that achieves a longer load life by increasing the load capacity and is lighter and more compact is provided. be able to.

  Preferably, as in the invention described in claim 2, if the balls of the inner ball row are arranged in the center between the ball pitches of the outer ball rows, the balls may be separated from each other even if the rotational angular velocity shifts. Interference can be prevented.

  Further, as in the invention according to claim 3, when the pitch circle diameters of the outer and inner ball rows are DPa and DPb, the ball diameters are Da and Db, and the contact angles are αa and αb, As long as (DPa−Da × cos αa) / DPa = (DPb−Db × cos αb) / DPb, the rotational angular velocities of the balls in each row are the same, and smooth rolling is obtained.

  Preferably, if the contact angles αa and αb are set to be the same (αa = αb) as in the invention described in claim 4, it is more difficult to interfere even if a rotational angle shift occurs.

  If the shoulder diameter of the outer ball row in the outer member is set larger than the circumscribed circle diameter of the inner ball row as in the invention according to claim 5, the bearing Assembling can be facilitated.

  If the shoulder diameter of the inner ball row in the inner member is set to be smaller than the inscribed circle diameter of the outer ball row as in the invention described in claim 6, Assembling can be facilitated.

  Further, as in the invention described in claim 7, when the cage is formed by injection molding from a thermoplastic synthetic resin and a fibrous reinforcing material is added, the strength and rigidity are increased, and the rotational angular velocity is increased. Durability can be improved over a long period of time without being damaged even if a deviation occurs.

  Preferably, as in the invention described in claim 8, the cage is constituted by a crown shape integrated with each row, and a clearance of a pocket for holding the ball is set in a range of 0.30 to 0.60 mm. As a result, even if the rotational angular velocity shifts, the durability can be further improved without being damaged.

  Further, as in the invention according to claim 9, the pitch circle diameter of the double row of outer rows of the four rows of balls is larger than the pitch circle diameter of the double row of rows of inner balls. If it is set to, the bearing rigidity of the outer side portion can be increased compared to the inner side, and the life of the bearing can be extended.

  Further, as in the invention according to claim 10, a double row inner rolling surface facing an outer side double row outer rolling surface among the four rows of outer rolling surfaces is provided on an outer periphery of the hub wheel. Directly formed and hardened to a surface hardness of 58 to 64 HRC by induction hardening from the inner side rolling surface of the double row to the small diameter step from the inner side base of the wheel mounting flange. Then, it has sufficient mechanical strength against the rotational bending load applied to the wheel mounting flange, and the fretting resistance of the small-diameter step portion that becomes the fitting portion of the inner ring is improved.

  The wheel bearing device according to the present invention has an outer member in which four rows of outer rolling surfaces are integrally formed on the inner periphery, and a wheel mounting flange for mounting the wheel at one end, and an axial direction on the outer periphery. 4 rows of inner races, each of which has a hub ring formed with a small-diameter step portion extending in the direction and at least one inner ring press-fitted into the small-diameter step portion of the hub ring, and which faces the outer race surface of the four rows on the outer periphery. An inner member formed with a surface, and four rows of ball rows that are slidably accommodated between both rolling surfaces of the inner member and the outer member via a cage, and are back to back type In the wheel bearing device constituted by the four-row angular ball bearing, the pitch circle diameter of the outer ball row is larger than the pitch circle diameter of the inner ball row with respect to the bearing center among the four rows of ball rows. And the ball diameter of the outer ball row is set to the inner Is set to be larger than the ball diameter of the ball row, the balls of the inner ball row are arranged between the ball pitches of the outer ball row, and the pitch between the outer ball row and the inner ball row is different from each other. Since it is set smaller than the sum of the radii of the balls, it is possible to provide a wheel bearing device that achieves a high load capacity and a long bearing life, and is lightweight and compact.

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 of FIG. FIG. 5 is a view taken in the direction of arrow III in FIG. 4. It is IV arrow line view 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 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, and an outer member in which four rows of outer rolling surfaces are integrally formed on the inner periphery, and a wheel attachment for attaching a wheel A double row inner rolling surface that has a flange at one end and faces the outer double row outer rolling surface of the four rows of outer rolling surfaces on the outer periphery, and inner rolling of these double rows A hub wheel formed with a small-diameter step portion extending in the axial direction from the surface, and a press-fitted into the small-diameter step portion of the hub wheel, and the outer side rolling surface of the inner side of the four rows of outer side rolling surfaces on the outer periphery And an inner member formed of an inner ring formed with a double row of inner rolling surfaces facing each other, and the inner member and the outer member are accommodated between the rolling surfaces of the inner member and the outer member via a cage. Wheel bearings comprising four rows of ball rows and comprising back-to-back type four row angular contact ball bearings The pitch circle diameter of the outer ball row with respect to the bearing center is set to be larger than the pitch circle diameter of the inner ball row of the four ball rows, and the balls of the outer ball row The outer diameter is set larger than the ball outer diameter of the inner ball row, the balls of the inner ball row are arranged in the center between the ball pitches of the outer ball row, and the pitch between the ball rows is respectively Is set to be smaller than the sum of the radii of the balls.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
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 of FIG. 1, FIG. 3 is a view taken along arrow III of FIG. [Fig. 4] is a view on arrow IV in Fig. 1. 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 a driven wheel, and is composed of four rows of balls 3a, 3b, which are accommodated in a freely rollable manner between the inner member 1, the outer member 2, and both members 1, 2. 3a and 3b columns. The inner member 1 includes a hub ring 4 and an inner ring 5 press-fitted into the hub ring 4 through a predetermined shimiro.

  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 one (outer side) double row inner rolling surfaces 4a and 4b on the outer periphery. A small-diameter step portion 4c extending in the axial direction from these double-row inner rolling surfaces 4a, 4b is formed. Hub bolts 6a are planted on the wheel mounting flange 6 at equal intervals in the circumferential direction.

  The inner ring 5 is formed with the other (inner side) double-row inner rolling surfaces 5a and 5b on the outer periphery, and is press-fitted into the small-diameter step portion 4c of the hub ring 4 to constitute a back-to-back type four-row angular ball bearing. At the same time, the inner ring 5 is fixed in the axial direction in a state where a predetermined bearing preload is applied by a caulking portion 4d formed by plastic deformation of the end portion of the small diameter step portion 4c. The inner ring 5 and the balls 3a and 3b 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 part by quenching.

  The hub wheel 4 is made of medium and high carbon steel containing 0.40 to 0.80 wt% of carbon such as S53C, and the inner rolling surface 4a and 4b as well as the inner side base portion 6b of the wheel mounting flange 6 and the small diameter step portion 4c. Therefore, the surface hardness is set to a range of 58 to 64 HRC by induction hardening. Note that the caulking portion 4d is left with a raw surface hardness after forging. Thereby, it has sufficient mechanical strength with respect to the rotational bending load applied to the wheel mounting flange 6, the fretting resistance of the small-diameter stepped portion 4c that becomes the fitting portion of the inner ring 5 is improved, and the minute There is no generation of cracks or the like, and the plastic working of the crimped portion 4d can be performed smoothly.

  The outer member 2 integrally has a vehicle body mounting flange 2c for being attached to a knuckle (not shown) on the outer periphery, and an outer member facing the double-row inner rolling surfaces 4a, 4b of the hub wheel 4 on the inner periphery. The outer side rolling surfaces 2a, 2b of the double row on the side and the outer side rolling surfaces 2a, 2b of the inner side facing the double row inner rolling surfaces 5a, 5b of the inner ring 5 are integrally formed. . Four rows of balls 3 a, 3 b, 3 a, 3 b are accommodated between these rolling surfaces and are held by the cages 7, 8 so as to roll freely. Seals 9 and 10 are attached to the opening of the annular space formed between the outer member 2 and the inner member 1, and leakage of grease sealed inside the bearing and rainwater from the outside. And dust are prevented from entering the bearing.

  The outer member 2 is formed of medium-high carbon steel containing 0.40 to 0.80 wt% of carbon such as S53C, and the four rows of outer rolling surfaces 2a, 2b, 2a, and 2b have a surface hardness of 58 to 58 by induction hardening. Hardened to a range of 64 HRC. In addition, although the 3rd generation structure by the side of a driven wheel was illustrated here, not only this but a 1st generation or a 2nd generation structure may be sufficient.

  Here, in the present embodiment, the pitch circle diameter DPoa of the outer ball 3a row with respect to the bearing center CL in the outer ball 3a, 3b row is larger than the pitch circle diameter DPob of the inner ball 3b row ( DPoa> DPob) and the pitch circle diameter DPia of the outer ball 3a row of the inner balls 3a, 3b row is larger than the pitch circle diameter DPib of the inner ball 3b row (DPia> DPib). Is set to Further, the diameter Da of the ball 3a is set to be larger than the diameter Db of the ball 3b (Da> Db). As shown in FIG. 2, when the contact angles are αa and αb, the relationship between the outer balls 3a and 3b is (DPoa−Da × cos αa) / DPoa = (DPob−Db × cos αb). / DPob is set. Similarly, although not shown, the relationship between the inner side balls 3a and 3b is set such that (DPia−Da × cos αa) / DPia = (DPib−Db × cos αb) / DPib. Thereby, the rotational angular velocities of the balls 3a and 3b in each row are the same, and smooth rolling is obtained. In addition, it is preferable that the contact angles αa and αb are the same (αa = αb) so that even if a rotational angle deviation occurs, interference is more difficult.

  Further, the number of balls Za in the row of balls 3a and the number of balls Zb in the row of balls 3b are set to the same number (Za = Zb), and as shown in FIG. 3, the inner balls 3b row is arranged between the ball pitches of the outer balls 3a row. Balls 3b are arranged, and the pitch P between the ball rows is set to be smaller than the sum of the radii of the balls 3a and 3b (P ≦ (Da + Db) / 2). As a result, it is possible to provide a wheel bearing device that achieves a high load capacity and a long bearing life and is lightweight and compact. Preferably, as shown in FIG. 4, if the balls 3b in the inner ball 3b row are arranged at the center between the ball pitches in the outer ball 3a row (θ1 = θ2), even if the rotational angular velocity shifts, Interference between the balls 3a and 3b can be prevented.

  In order to facilitate the assembly of the bearing, in the present embodiment, as shown in FIG. 2, in the outer member 2, the shoulder diameter D1 of the outer ball 3a row is the circumscribed circle of the inner ball 3b row. The diameter is set to be larger than the diameter D2 (D1> D2), and in the hub wheel 4 (inner ring 5), the shoulder diameter d1 of the inner ball 3a row is larger than the inscribed circle diameter d2 of the outer ball 3b row. Is also set to a small diameter (d1 <d2).

  The cages 7 and 8 are formed by injection molding from a thermoplastic synthetic resin made of PA (polyamide) 66, and 10 to 50 wt% of a fibrous reinforcing material made of GF (glass fiber) is added. As a result, strength and rigidity are increased, and durability can be improved over a long period of time without being damaged even if a deviation in rotational angular velocity occurs. In addition to the above materials, the cages 7 and 8 can be exemplified by synthetic resins such as polyphenylene sulfide (PPS) and PA6 / 12 that can be injection molded. Moreover, as a fibrous reinforcement, not only GF but CF (carbon fiber), an aramid fiber, a boron fiber, etc. can be illustrated other than this.

  Here, the cages 7 and 8 are formed in an integral crown shape, and the clearance of the pockets for holding the balls 3a and 3b is twice that of the conventional general snap-on type clearance of 0.15 to 0.30 mm, that is, , 0.30 to 0.60 mm. Thereby, even if the deviation of the rotational angular velocity occurs, the durability can be further improved without being damaged.

  FIG. 5 is a longitudinal sectional view showing a second embodiment of the wheel bearing device according to the present invention. Note that this embodiment is basically the same as the first embodiment described above except that the pitch circle diameters of the outer ball array and the inner ball array differ from each other, and the same parts or the same functions are the same. The same reference numerals are assigned to the components and parts that are provided, and detailed description thereof is omitted.

  The wheel bearing device includes an inner member 11 and an outer member 12, and four rows of balls 13a, 13b, 3a, and 3b that are accommodated so as to roll between the members 11 and 12. The inner member 11 includes a hub ring 14 and an inner ring 5 press-fitted into the hub ring 14 through a predetermined shimiro.

  The hub wheel 14 integrally has a wheel mounting flange 6 at an end portion on the outer side, one (outer side) double row inner raceway surfaces 14a and 14b on the outer periphery, and these double row inner raceway surfaces. A small diameter step 4c extending in the axial direction from 14a, 14b is formed. The hub wheel 14 is made of medium and high carbon steel containing 0.40 to 0.80 wt% of carbon such as S53C, and has a small diameter step from the inner rolling surface 14a, 14b and the inner side base 6b of the wheel mounting flange 6. The surface hardness is hardened in the range of 58 to 64 HRC by induction hardening over 4c.

  The outer member 12 integrally has a vehicle body mounting flange 2c on the outer periphery, and an outer-side double-row outer rolling surface 12a opposed to the double-row inner rolling surfaces 14a and 14b of the hub wheel 14 on the inner periphery. 12b and the inner side double row outer raceway surfaces 2a, 2b opposite to the inner row 5 double row inner raceway surfaces 5a, 5b are integrally formed. Double rows of balls 13a, 13b, 3a, 3b are accommodated between these rolling surfaces, and are held by rollers 15 and 8 so as to roll freely. This outer member 12 is made of medium-high carbon steel containing 0.40 to 0.80 wt% of carbon such as S53C, and four rows of outer rolling surfaces 12a, 12b, 2a and 2b have a surface hardness of 58 by induction hardening. Cured to a range of ~ 64 HRC. Seals 16 and 10 are attached to the opening portion of the annular space formed between the outer member 12 and the inner member 11, and leakage of grease sealed inside the bearing and rainwater from the outside. And dust are prevented from entering the bearing.

  In the present embodiment, the pitch circle diameter DPoa of the outer ball 13a row with respect to the bearing center CL in the outer ball 13a, 13b row is larger than the pitch circle diameter DPob of the inner ball 13b row (DPoa> DPob). ) And the pitch circle diameter DPia of the outer ball 3a row of the inner balls 3a and 3b rows is set to be larger than the pitch circle diameter DPib of the inner ball 3b row (DPia> DPib). ing. Further, the diameter Da of the ball 3a is set to be larger than the diameter Db of the ball 3b (Da> Db).

  Here, the pitch circle diameter DPoa of the outer side ball 13a row is set to be larger than the pitch circle diameter DPia of the inner side ball 3a row (DPoa> DPia), and the pitch circle of the outer side ball 13b row is set. The diameter DPob is set to be larger than the pitch circle diameter DPib of the inner ball 3b row (DPob> DPib). Thereby, the bearing rigidity of an outer side part can be increased compared with an inner side, and lifetime improvement of a bearing can be achieved.

  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.

  The wheel bearing device according to the present invention can be applied to a wheel bearing device having a first to third generation structure regardless of whether it is for driving wheels or driven wheels.

1, 11 Inner member 2, 12 Outer member 2a, 2b, 12a, 12b Outer rolling surface 2c Car body mounting flange 3a, 3b, 13a, 13b Ball 4, 14 Hub wheel 4a, 4b, 5a, 5b Inner rolling Surface 4c Small-diameter stepped portion 4d Caulking portion 5 Inner ring 6 Wheel mounting flange 6a Hub bolt 6b Base portion 7, 8, 15 on the inner side of the wheel mounting flange Cage 9, 16 Outer side seal 10 Inner side seal 51 Outer member 51a 51b Outer rolling surface 51c Car body mounting flange 52 Hub wheel 52a Small-diameter stepped portion 52b Clamping portion 53 Wheel mounting flange 54 Inner ring 54a, 54b Inner rolling surface 55 Inner members 56a, 56b Balls 57, 58 Cage 59, 60 Seal CL Bearing center d1 Shoulder diameter of the inner ball row in the hub ring (inner ring) d2 Inscribed contact of the outer ball row in the hub ring (inner ring) Diameter D1 Shoulder diameter D2 of the outer ball row in the outer member Outer circle diameter Da of the inner ball row in the outer member Ball diameter Db of the outer ball row Ball diameter DPia of the inner ball row DPoa, DPoa of the outer ball row Pitch circle diameter DPib, DPob Pitch circle diameter ME of the inner ball row P Surface perpendicular to the longitudinal direction of the bearing P Ball pitch between ball rows TK1, TK4 First pitch circle diameter TK2, TK3 Second pitch circle diameter Za Number of balls in the outer ball row Zb Number of balls in the inner ball row αa Contact angle of the outer ball row αb Contact angle θ1, θ2 of the outer ball row Ball phase angle

Claims (10)

An outer member in which four rows of outer rolling surfaces are integrally formed on the inner periphery;
It has a wheel mounting flange for mounting a wheel at one end, a hub wheel formed with a small-diameter step portion extending in the axial direction on the outer periphery, and at least one inner ring press-fitted into the small-diameter step portion of the hub wheel, An inner member in which four rows of inner rolling surfaces opposed to the four rows of outer rolling surfaces are formed on the outer periphery;
The inner member and the outer member are provided with four rows of ball rows that are slidably accommodated via a cage between the rolling surfaces of the outer member, and are constituted by back-to-back type four-row angular ball bearings. In the wheel bearing device,
Of the four rows of balls, the pitch circle diameter of the outer ball row with respect to the bearing center is set larger than the pitch circle diameter of the inner ball row, and the ball diameter of the outer ball row is It is set larger than the ball diameter of the inner ball row, the balls of the inner ball row are arranged between the ball pitches of the outer ball row, and the pitch between the outer ball row and the inner ball row is respectively The wheel bearing device is set smaller than the sum of the radii of the balls.   The wheel bearing device according to claim 1, wherein the balls of the inner ball row are arranged in the center between the ball pitches of the outer ball row.   When the pitch circle diameters of the outer and inner ball rows are DPa and DPb, the ball diameters are Da and Db, and the contact angles are αa and αb, respectively, (DPa−Da × cos αa) / DPa = (DPb− The wheel bearing device according to claim 1, wherein the wheel bearing device is set to satisfy Db × cos αb) / DPb.   The wheel bearing device according to claim 3, wherein the contact angles αa and αb are set to be the same (αa = αb).   The wheel bearing device according to any one of claims 1 to 4, wherein a shoulder diameter of the outer ball row in the outer member is set larger than a circumscribed circle diameter of the inner ball row.   The wheel bearing device according to any one of claims 1 to 5, wherein a shoulder diameter of the inner ball row in the inner member is set to be smaller than an inscribed circle diameter of the outer ball row.   The wheel bearing device according to claim 1, wherein the cage is formed from a thermoplastic synthetic resin by injection molding, and a fibrous reinforcing material is added.   The wheel bearing device according to claim 7, wherein the cage is configured by a crown shape integrated with each row, and a clearance of a pocket for holding the ball is set in a range of 0.30 to 0.60 mm.   9. The pitch circle diameter of the outer double-row ball row among the four rows of balls is set larger than the pitch circle diameter of the inner-side double row ball row. The wheel bearing device described.   A double-row inner rolling surface that directly faces an outer-side double-row outer rolling surface among the four rows of outer-rolling surfaces is directly formed on the outer periphery of the hub wheel, First, the wheel hardness according to any one of claims 1 to 9, wherein the surface hardness is hardened to a range of 58 to 64 HRC by induction hardening from a base portion on an inner side of the wheel mounting flange to the small diameter step portion. Bearing device.

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