JP2009197901A - Wheel bearing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wheel bearing device assembled in an automobile assembling factory with less manhours, having improved productivity and reduced in cost. <P>SOLUTION: A rolling bearing 2 consists of: an outer ring 25 having double-row outside rolling surfaces 26, 27 formed on the inner periphery; a pair of inner rings 24 having inside rolling surfaces 28, 29 formed on the outer periphery in opposition to the outside rolling surfaces 26, 27; and double-row rolling elements 30 rollingly stored between each of the outside rolling surfaces 26, 27 of the outer ring and each of the inside rolling surfaces 28, 29 of the inner rings. The rolling bearing 2 with the outer ring 25 formed at least by cold rolling and assembled thereon is pressed into a hub ring 1 to be integrated therewith. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a wheel bearing device for rotatably supporting a wheel with respect to a vehicle body in a vehicle such as an automobile.

  The wheel bearing device has evolved from a structure in which a double row rolling bearing called a first generation is used alone to a second generation in which a vehicle body mounting flange is integrated with an outer member. The third generation in which the inner raceway is integrally formed on one of the double row rolling bearings on the outer periphery of the hub wheel having an integral, and the constant velocity universal joint is integrated with the hub wheel. A fourth generation type has been developed in which the other inner rolling surface of the double row rolling bearing is integrally formed on the outer periphery of the outer joint member constituting the joint.

  In such a wheel bearing device, it is necessary to press-fit into a knuckle on the vehicle body side. For this reason, the first generation wheel bearing device requires man-hours for assembly and replacement. However, since the first-generation wheel bearing device can be manufactured at a lower cost than the second-generation or third-generation wheel bearing device, it is often used for small vehicles.

  As shown in FIG. 6, the wheel bearing device called the first generation includes a hub wheel 102 having a flange 101 extending in the outer diameter direction, and a constant velocity universal joint 104 in which an outer joint member 103 is fixed to the hub wheel 102. And a bearing 100 disposed on the outer peripheral side of the hub wheel 102.

  The constant velocity universal joint 104 includes the outer joint member 103, an inner joint member (not shown) disposed on the outer joint member 103, and a ball disposed between the inner joint member and the outer joint member 103. (Not shown) and a cage (not shown) for holding the ball. The outer joint member 103 includes a bowl-shaped mouth portion 107 in which the inner joint member is accommodated, and a shaft portion (stem portion) 123 protruding from the mouth portion 107.

  The hub wheel 102 includes a cylindrical portion 113 and the flange 101. A large-diameter first portion 115a and a small-diameter second portion 115b are provided on the outer end surface 114 (end surface on the anti-joint side) of the flange 101. The brake rotor is fitted on the first portion 115a, and the wheel is fitted on the second portion 115b.

  The bearing 100 has a pair of outer rings 105 having double-row outer rolling surfaces 120 and 121 formed on the inner periphery, and a pair of inner rolling surfaces 118 and 119 facing the outer rolling surfaces 120 and 121 on the outer periphery. Inner rings 108 and 109, and double row rolling elements 122 accommodated so as to roll freely between outer rolling surfaces 120 and 121 of the outer ring 105 and inner rolling surfaces 118 and 119 of the inner rings 108 and 109 are provided. A notch 116 is provided on the outer peripheral surface of the tube portion 113 of the hub wheel 102, and the inner rings 108 and 109 are fitted into the notch 116. Further, a bolt mounting hole 112 is provided in the flange 101 of the hub wheel 102, and a hub bolt 141 for fixing the wheel and brake rotor 140 to the flange 101 is mounted in the bolt mounting hole 112.

  The shaft portion 123 of the outer joint member 103 is inserted into the tube portion 113 of the hub wheel 102. The shaft portion 123 has a screw portion 124 formed at the end of the anti-mouse portion, and a spline portion 125 is formed between the screw portion 124 and the mouse portion 107. Further, a spline portion 126 is formed on the inner peripheral surface (inner diameter surface) of the tube portion 113 of the hub wheel 102, and when the shaft portion 123 is inserted into the tube portion 113 of the hub wheel 102, The spline portion 125 engages with the spline portion 126 on the hub wheel 102 side.

  Then, the nut member 127 is screwed onto the threaded portion 124 of the shaft portion 123 protruding from the cylindrical portion 113, and the hub wheel 102 and the outer joint member 103 are connected. At this time, the inner end surface (back surface) 128 of the nut member 127 and the outer end surface 129 of the cylindrical portion 113 are in contact with each other, and the end surface 130 on the shaft portion side of the mouse portion 107 and the end surface 131 of the inner ring 109 are in contact with each other. That is, by tightening the nut member 127, the hub wheel 102 is sandwiched between the nut member 127 and the mouth portion 107 via the inner rings 108 and 109. At this time, the notch end surface 132 of the hub wheel 102 and the end surface 133 of the inner ring 108 are in contact with each other, and the end surfaces 130 of the mouth portion 107 and the end surface 131 of the inner ring 109 are in contact with each other. 135 and 136 are abutted.

  Further, the outer diameter surface of the outer ring 105 of the bearing 100 serves as a fitting surface 105a and is press-fitted into the inner diameter surface 145a of the knuckle 145 on the vehicle body side.

In the structure shown in FIG. 6, both the outer ring 105 and the inner rings 108 and 109 are formed by turning or the like. However, in recent years, in order to reduce the weight and cost, methods for press-molding the outer ring and the inner ring from a plate material or a pipe material have been proposed (Patent Document 1, Patent Document 2, and Patent Document 3).
JP 2004340403 A Japanese Utility Model Publication No. 6-1835 US Pat. No. 5,177,869

  However, even if it is what is shown in FIG. 6, and what is shown in patent document 1-patent document 3 etc., the improvement which requires a man-hour for an assembly operation or a replacement | work operation has not been made | formed. That is, even the ones shown in Patent Literature 1 to Patent Literature 3 and the like apply preload to the inner ring at the shoulder portion (end surface 130 of the mouse portion 107) of the outer joint member of the constant velocity universal joint. Prior to shipping to the factory, the process of fitting the hub wheel into the bearing could not be performed, and this process had to be performed at the assembly plant. For this reason, the number of assembly steps in an automobile assembly plant is large, and it has not been possible to improve productivity.

  In view of the above problems, the present invention provides a wheel bearing device that can reduce the number of assembly steps in an automobile assembly factory, is excellent in productivity, and can reduce costs.

  The wheel bearing device of the present invention includes an outer ring having a double row outer rolling surface formed on the inner periphery, a pair of inner rings formed with an inner rolling surface facing the outer rolling surface on the outer periphery, and an outer ring A double row rolling element that is slidably accommodated between the outer rolling surface and the inner rolling surface of the inner ring, and at least the outer ring is formed by cold rolling, and the outer ring, the inner ring, and the rolling element Are assembled into the hub wheel by press-fitting. Here, cold rolling (cold rolling) is a processing method in which a material (blank) is rolled while being kept cold (normal temperature) without applying heat.

  In the wheel bearing device of the present invention, since the assembled rolling bearing is integrated into the hub wheel by press-fitting, the step of press-fitting the hub wheel into the bearing at the customer (automobile assembly plant, etc.) Can be omitted.

  Moreover, since the outer ring is formed by cold rolling (cold rolling), it is possible to improve the yield of the material of the outer ring. In other words, unlike the rolling process in which an extra portion of the material is scraped off, the cold rolling can form a material that is thinner than the outer diameter of the product and does not cause material waste. In addition, productivity is higher than cutting because the machining time is short and the tool has a long life. Furthermore, although the tool (die) to be used needs to be replaced | exchanged according to a workpiece, the stable processing precision can be obtained. Furthermore, unlike the cutting process, the fiber flow (fibrous metal structure) is not cut, and the work surface is compositionally cured by plastic deformation. Therefore, the processed product can obtain a strong strength.

  It is preferable to provide a circumferential recess at the axial central portion of the outer diameter surface of the outer ring by providing a bulging portion that bulges toward the inner diameter side at the axial central portion of the inner diameter surface of the outer ring. That is, a rolling surface can be formed on the inner diameter surface by providing a bulging portion that bulges toward the inner diameter side at the axially central portion of the inner diameter surface of the outer ring. Moreover, the thickness of the outer ring can be maintained substantially constant along the axial direction.

  The inner ring is preferably made of cold rolling or a press plate. If the inner ring is made of cold rolling, it is possible to improve the yield and productivity as well as the outer ring, to obtain a stable processing accuracy, and to obtain a strong strength. Even if the inner ring is made of a press plate, the yield and productivity can be improved, and stable processing accuracy can be obtained.

  A preload may be applied to the inner ring of the rolling bearing press-fitted into the hub ring by crimping the end of the hub ring.

  The outer ring may be hardened steel cut by cutting after heat treatment after cold rolling forming. This hardened steel cutting is simply a cutting, and since the cutting is usually performed in the state of raw material, it was called hardened steel cutting in order to clarify that the cutting was after heat treatment (after quenching). . Since cutting is performed after quenching, the heat treatment deformation of the material can be removed in this cutting process. When quenching, tensile residual stress tends to remain, and fatigue strength decreases as it is. For this reason, if the surface is cut, a compressive residual stress can be given to the outermost surface portion, thereby improving the fatigue strength.

  Preferably, a fitting surface is formed on the outer diameter surface of the outer ring, and this fitting surface is press-fitted into the knuckle.

  The wheel bearing device may be for driving wheels or for driven wheels.

  In the wheel bearing device of the present invention, the step of press-fitting the hub wheel into the bearing at the customer can be omitted, the number of assembly steps at the customer can be reduced, and the assembly workability can be improved. In addition, at least the yield and productivity of the outer ring can be improved, and cost reduction can be achieved. In addition, the outer ring can obtain stable processing accuracy and strong strength, and can achieve improved bearing quality.

  By providing a bulged portion that bulges toward the inner diameter side at the axially central portion of the inner diameter surface of the outer ring, a rolling surface can be formed on the inner diameter surface, and the outer ring can be easily formed. In addition, the thickness of the outer ring can be maintained substantially constant along the axial direction, and weight reduction and cost reduction can be achieved. That is, by providing a circumferential recess in the axial center of the outer diameter surface, a functionally useless part of the meat can be omitted, and weight reduction can be achieved.

  If the inner ring is made of cold rolling or a press plate, like the outer ring, the yield and productivity of the inner ring can be improved, and cost reduction can be achieved. In addition, the inner ring can obtain stable machining accuracy and strong strength, and can improve the quality of the entire bearing.

  If the end of the hub ring is crimped and a preload is applied to the inner ring of the rolling bearing press-fitted into the hub ring, high-quality rotation can be obtained.

In the outer ring subjected to hardened steel cutting, compressive residual stress can be applied to the outermost surface portion, fatigue strength can be improved, and a stable function can be exhibited over a long period of time.

If the outer ring is formed with a fitting surface on the outer diameter surface and the fitting surface is press-fitted into the knuckle, the assembling work can be further simplified.

The wheel bearing device may be used for a driving wheel or a driven wheel, and each function can be effectively exhibited.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. FIG. 2 shows a wheel bearing device (drive wheel bearing device) according to the first embodiment. The wheel bearing device includes a hub wheel 1, a double row rolling bearing 2, and a constant velocity universal joint 3. It becomes.

  The constant velocity universal joint 3 includes a plurality of outer rings 5 serving as outer joint members, an inner ring 6 serving as an inner joint member disposed on the inner side of the outer ring 5, and a plurality of torque transmissions interposed between the outer ring 5 and the inner ring 6. The ball 7 and the cage 8 that is interposed between the outer ring 5 and the inner ring 6 and holds the ball 7 are configured as main members. The inner ring 6 is spline-fitted by press-fitting an end of a shaft (not shown) into the shaft hole inner diameter 6a and is coupled to the shaft so that torque can be transmitted.

  The outer ring 5 is composed of a mouse part 11 and a stem part (shaft part) 12. The mouse part 11 has a bowl shape opened at one end, and a plurality of track grooves 14 extending in the axial direction are circumferentially formed on the inner spherical surface 13 thereof. It is formed at equal intervals in the direction. The track groove 14 extends to the open end of the mouse portion 11. In the inner ring 6, a plurality of track grooves 16 extending in the axial direction are formed on the outer spherical surface 15 at equal intervals in the circumferential direction.

  The track groove 14 of the outer ring 5 and the track groove 16 of the inner ring 6 make a pair, and one ball 7 as a torque transmitting element can roll on each ball track constituted by the pair of track grooves 14 and 16. It is incorporated. The ball 7 is interposed between the track groove 14 of the outer ring 5 and the track groove 16 of the inner ring 6 to transmit torque. The constant velocity universal joint in this case is a Zepper type, but may be another constant velocity universal joint such as an undercut free type having a straight straight portion at the bottom of each track groove.

  The outer ring 5 and the inner ring 6 of the constant velocity universal joint 3 are made of, for example, medium carbon steel containing 0.40 to 0.80 wt% of carbon such as S53C, and the shoulder portions of the track grooves 14 and 16 and the mouth portion 11 of the outer ring 5. From the (bottom wall outer surface 11a), the outer peripheral surface (outer diameter surface) of the shaft portion 12 is subjected to a hardening process with a hardness of about 58 to 64 HRC by induction hardening or the like.

  The hub wheel 1 includes a cylindrical portion 20 and a flange 21 provided at an end of the cylindrical portion 20 on the side opposite to the joint. Further, the shaft portion 12 of the outer ring 5 is inserted into the hole portion 22 of the cylindrical portion 20 of the hub wheel 1. The shaft portion 12 has a screw portion 40 formed at the end of the anti-mouse portion 11, and a spline portion 41 is formed between the screw portion 40 and the mouse portion 11. A spline portion 42 is formed on the inner peripheral surface (inner diameter surface) of the cylindrical portion 20 of the hub wheel 1. When the shaft portion 12 is inserted into the cylindrical portion 20 of the hub wheel 1, The spline portion 41 engages with the spline portion 42 on the hub wheel 1 side.

  Then, the nut member 43 is screwed onto the screw portion 40 of the shaft portion 12 protruding from the cylindrical portion 20, and the hub wheel 1 and the outer ring 5 are connected. At this time, the end face 45 of the hub wheel 1 on the side opposite to the mouse portion is provided with a recessed portion 46 along the opening of the hole portion 22, and the seat portion of the nut member 43 is fitted into the recessed portion 46. ing. A bolt mounting hole 32 is provided in the flange 21 of the hub wheel 1, and a hub bolt 33 for fixing the wheel and the brake rotor 90 to the flange 21 is mounted in the bolt mounting hole 32. The hub wheel 1 is made of, for example, medium carbon steel containing 0.40 to 0.80 wt% of carbon such as S53C, and at least the bottom surface or the end surface 70 of the notch has a hardness of about 58 to 64 HRC by induction hardening or the like. A curing treatment is applied.

  As shown in FIG. 1, the rolling bearing 2 includes an outer ring 25 in which double-row outer rolling surfaces 26 and 27 are formed on the inner periphery, and an inner rolling that faces the outer rolling surfaces 26 and 27 of the outer ring 25 on the outer periphery. Rolled between a pair of inner races 24A and 24B on which running surfaces 28 and 29 are formed, outer raceway surfaces 26 and 27 of outer race 25 and inner raceway surfaces 28 and 29 of inner races 24A and 24B. And double row rolling elements 30. The rolling element 30 is held by a cage 31 interposed between the outer ring 25 and the inner rings 24A and 24B. A seal member S is mounted on both openings of the rolling bearing 2 (openings between the outer ring 25 and the inner rings 24A and 24B).

  As shown in FIG. 3, the outer ring 25 has a circumferential recess 51 formed at the axial center of the outer diameter surface 50, and correspondingly, a circumferential protrusion (bulging portion) at the axial center of the inner diameter surface. ) 53 is provided. Outer rolling surfaces 26 and 27 are formed on both sides of the circumferential convex portion 53, and seal grooves 54 and 55 are formed on the outer sides of the outer rolling surfaces 26 and 27. Of the outer diameter surface 50 of the outer ring 25, a portion where the circumferential recess 51 is omitted becomes fitting surfaces 50 a and 50 a that are press-fitted into the knuckle N, as will be described later.

  The outer ring 25 is formed by cold rolling on a blank (material) of a pipe material. Here, cold rolling (cold rolling) is a processing method in which a material (blank) is rolled while being kept cold (normal temperature) without applying heat. In other words, two blanks (inner diameter and outer diameter) that are designed to have the inner and outer diameters smaller than the workpiece (finished product after machining) and basically the inner and outer diameter straight blanks (materials) to be machined. It is a processing method that forms a workpiece by rolling (rolling) while rotating it.

  Specifically, the raw material of the outer ring that is substantially the shape of the outer ring 25 is formed by cold rolling. This material is hardened in a heating furnace or the like to be hardened and then cut. In this case, as shown by the broken line in FIG. 3, the seal grooves 54 and 55 at the axial end of the inner diameter surface 52, the rolling surfaces 26 and 27, the both end surfaces 56 and 57, and the fitting surface 50a of the outer diameter surface. , 50a. For this reason, these cuttings can be called hardened steel cutting. In other words, hardened steel cutting is simply cutting, and since cutting is usually performed in the state of raw material, it was called hardened steel cutting in order to clarify that the cutting was after heat treatment (after quenching). . Since cutting is performed after quenching, the heat treatment deformation of the material can be removed in this cutting process. When quenching, tensile residual stress tends to remain, and fatigue strength decreases as it is. For this reason, if the surface is cut, a compressive residual stress can be given to the outermost surface portion, thereby improving the fatigue strength.

  As the material of the outer ring 25, carburized steel such as SCr420 and SCM415, carbon steel such as SCM440, cold rolled steel, S53C, and bearing steel such as SUJ2 can be used. In the case of carburized steel, a hardening process (heat treatment) is performed by carburizing and quenching, and in the case of cold rolled steel, carbon steel, or the like, the hardening process (heat treatment) is performed by induction hardening or sub-firing.

  The inner ring 24A on the outboard side and the inner ring 24B on the inboard side can be configured by common parts. Note that the side closer to the outside of the vehicle when assembled to the vehicle is referred to as the outboard side (left side in the drawing), and the side closer to the center is referred to as the inboard side (right side in the drawing).

The inner ring 24 (24 </ b> A, 24 </ b> B) includes a large diameter portion 60, a small diameter portion 61, and a tapered portion 62 between the large diameter portion 60 and the small diameter portion 61. In this case, the outer diameter surface of the large diameter portion 60 becomes the seal mounting surface 63, and the outer diameter surface of the tapered portion 62 becomes the rolling surface 28 (29). Further, the inner diameter surface of the small diameter portion 61 becomes the hub wheel fitting surface 64.

  Similarly to the outer ring 25, the inner ring 24 is formed by cold rolling of a raw material of the inner ring that is substantially the shape of the inner ring 24. This material is hardened in a heating furnace or the like to be hardened and then cut. That is, hardened steel cutting is performed. In this case, as indicated by a broken line in FIG. 4, the hub wheel fitting surface 64, both end surfaces 65 and 66, the seal mounting surface 63, and the rolling surface 28 (29) are hardened steel cut. The material of the inner ring 24 is the same as that of the outer ring 25. The inner ring 24 may be formed by press work other than cold rolling.

  Next, a method for assembling the wheel bearing device configured as described above will be described. First, as shown in FIG. 1, a unit body in which a bearing 2 is incorporated in a hub wheel 1 is formed. That is, the fitting surfaces 64 and 64 of the inner rings 24A and 24B of the bearing 2 in the assembled state are press-fitted into the outer diameter surface 20a of the cylindrical portion 20 of the hub wheel 1. At this time, the end surface 65 of the inner ring 24 </ b> A contacts the boss portion end surface 70 of the hub wheel 1.

  The unit body assembled in this way and the outer ring 5 of the constant velocity universal joint 3 are connected. At this time, the stem shaft portion 12 of the outer ring 5 is inserted into the hole portion 22 of the hub wheel 1, and the nut member 43 is screwed onto the screw portion 40 protruding from the hole portion 22 toward the outboard side. As a result, as shown in FIG. 2, the bottom wall outer surface 11 a of the mouse portion 11 contacts the end surface 65 of the inner ring 24 </ b> B on the inboard side.

  For this reason, the pair of inner rings 24A, 24B are sandwiched between the boss portion end surface 70 and the bottom wall outer surface 11a of the mouth portion 11 in a state where the abutting surfaces which are the end surfaces 66, 66 on the small diameter side are abutted, Preload can be applied to the inner rings 24A, 24B.

  In the wheel bearing device configured as described above, the knuckle fitting surface 50 a of the outer ring 25 of the rolling bearing 2 is press-fitted into the inner diameter surface 80 of the knuckle N. In this case, the outer diameter D11 of the knuckle fitting surface 50a is set slightly larger than the inner diameter D10 of the inner diameter surface 80 of the knuckle N. That is, the relative axial and circumferential deviation between the knuckle N and the outer ring 25 is regulated by the tightening allowance between the knuckle fitting surface 50a and the knuckle inner diameter surface 80.

  In this case, for example, when the hameai contact pressure / hameai area between the outer ring 25 and the knuckle N is taken as the hameai load, a value obtained by dividing the hameai load by the equivalent radial load of the rolling bearing is defined as a creep generation limit coefficient. The design specification of the outer ring 25 is set in consideration of the creep generation limit coefficient in advance.

  For this reason, due to the tightening allowance between the knuckle fitting surface 50a and the knuckle inner diameter surface 80, the outer ring 25 can be prevented from coming off in the axial direction and in the circumferential direction. Here, creep means that the bearing surface slightly moves in the circumferential direction due to insufficient fitting tightening allowance or poor processing accuracy of the mating surface, and the mating surface becomes mirror-finished. Say.

  Further, a bulging portion 81 protruding toward the inner diameter side is provided on the knuckle inner diameter surface 80, and the end surface 25a on the inboard side of the outer ring 25 comes into contact with the bulging portion 81 by press-fitting the bearing 2 from the outboard side. ing.

  As shown in FIG. 2, a brake rotor 90 is attached to the hub wheel 1. The brake rotor 90 includes a short cylindrical center mounting portion 92 having an axial hole 91, and the center mounting portion 92 is fitted to the flange portion 21 of the hub wheel 1.

  The center mounting portion 92 includes a disc portion 92a having a through hole, and a short cylindrical portion 92b extending from the outer diameter portion of the disc portion 92a to the inboard side. An outer flange portion 93 extending toward the outboard side is provided at the peripheral portion of the through hole of the disk portion 92a, and the axial hole 91 is configured by the inner diameter hole of the outer flange portion 93 and the through hole of the disk portion 92a. Is done.

  In this case, the hub wheel 1 is composed of an end surface on the outboard side (an end surface 45 on the outboard side of the tubular portion 20 and an end surface on the outboard side of the flange portion 21 disposed continuously on the same plane. The disk portion 92a comes into contact with the end surface of the hub wheel 1 and the inner diameter surface on the disk portion 92a side of the short cylindrical portion 92b comes into contact with the outer diameter portion 21a of the flange portion 21 of the hub wheel 1. That is, the outer diameter portion 21 a of the flange portion 21 of the hub wheel 1 constitutes a brake pilot portion 95 that guides the brake rotor 90. The disk portion 92a is provided with a through hole 96 through which the hub bolt 33 is inserted.

  As described above, when the brake rotor 90 is mounted, the outer diameter surface of the outer flange portion 93 constitutes the wheel pilot portion 97 that fits to the inner periphery of the wheel (not shown).

  In the wheel bearing device of the present invention, since the assembled rolling bearing 2 is integrated into the hub wheel 1 by press fitting, the hub wheel 1 is attached to the bearing 2 at the customer (automobile assembly plant or the like). The step of press-fitting can be omitted. For this reason, the number of assembling steps at the customer can be reduced, and the assembling workability can be improved.

  Since the outer ring 25 is formed by cold rolling (cold rolling), the yield and productivity of the outer ring 25 can be improved, and cost reduction can be achieved. In addition, the outer ring 25 can obtain stable processing accuracy and strong strength, and can improve the quality of the bearing 2. In the present invention, since the inner ring 24 is also made of cold rolling or a press plate, like the outer ring 25, the yield and productivity of the inner ring can be improved, and cost reduction can be achieved. In addition, the inner ring 24 can obtain stable processing accuracy and strong strength, and can improve the quality of the entire bearing.

  By providing a bulging portion 53 that bulges toward the inner diameter side at the axially central portion of the inner diameter surface of the outer ring 25, the rolling surfaces 26 and 27 can be formed on the inner diameter surface, facilitating the molding of the outer ring 25. Can be planned. In addition, the thickness of the outer ring 25 can be maintained substantially constant along the axial direction, and weight reduction and cost reduction can be achieved. That is, by providing the circumferential recessed portion 51 at the axially central portion of the outer diameter surface of the outer ring 25, a functionally useless portion of the meat portion can be omitted, and weight reduction can be achieved.

  When the end of the hub wheel 1 is crimped and preload is applied to the inner ring 24 of the rolling bearing 2 press-fitted into the hub wheel 1, high-quality rotation can be obtained. Since the outer ring 25 of the present invention has been subjected to quenching steel cutting, it can impart compressive residual stress to the outermost surface portion, improve fatigue strength, and exhibit a stable function over a long period of time. When the fitting surface 50a is formed on the outer diameter surface of the outer ring 25 and the fitting surface 50a is press-fitted into the knuckle N, the assembling work can be further simplified.

  By attaching a member different from the hub wheel 1 to the hub wheel 1, the wheel pilot portion 97 can be configured on the hub wheel 1. Therefore, the hub wheel 1 does not need to be integrally provided with the wheel pilot portion 97 fitted to the inner periphery of the wheel, and the shape of the entire hub wheel can be simplified. As a result, the productivity can be improved and the cost can be reduced. In addition, when the wheel pilot portion 97 attached to the hub wheel 1 is damaged, it is only necessary to replace the wheel pilot portion 97 of another member without replacing the entire hub wheel, and the cost can be reduced. .

  Next, FIG. 5 shows another embodiment. In this case, the inner ring 24 (24C, 24D) is not formed by cold rolling from a pipe material, but the same as the conventional one shown in FIG. 6 is used. Yes.

  The wheel bearing device shown in FIG. 5 is a follower, and the hub wheel 1 has a solid shaft portion 20A and a flange portion 21A projecting from the shaft portion 20A. The inner rings 24C and 24D are made of a short cylindrical body having a thick portion 85 and a thin portion 86, and a rolling surface 28 (29) is formed on the outer diameter surface between the thick portion 85 and the thin portion 86. Is done. The thin wall portion 86 is press-fitted into the outer diameter surface 20 </ b> Aa of the shaft portion 20 </ b> A of the hub wheel 1 in a state where the end surfaces (butting end surfaces) 86 a and 86 a of the thin portion 86 are butted.

  In this case, a boss portion 87 having an end surface 87a extending in a direction orthogonal to the axial direction and a concave curved surface 87b is provided between the flange portion 21A and the shaft portion 20A. For this reason, the inner diameter surface of the thick portion 85 of the inner ring 24C on the outboard side is a convex curved surface 88 corresponding to the concave curved surface 87b. On the other hand, such a convex curved surface is not formed on the inner diameter surface of the inner ring 24D on the inboard side.

  The end portion on the inboard side of the hub wheel 1 is a cylindrical portion 89, and the end portion on the inboard side of the cylindrical portion 89 is crimped to the outer diameter side. Preload is applied to the inner ring 24 via the end face 85a of the inner ring 24D on the side. A pilot portion 84 is provided on the end face of the hub wheel 1 on the outboard side.

  Other configurations of the wheel bearing device of FIG. 5 are the same as those of the wheel bearing device shown in FIG. 1, and the same members as those of the wheel bearing device shown in FIG. Omitted. For this reason, the effect which is the same as that of the wheel bearing device shown in FIG. 1 can be obtained by omitting the point that the inner ring 24 is not formed by cold rolling.

  As described above, the wheel bearing device of the present invention may be used for a drive wheel or a driven wheel, and can effectively exhibit each function.

  As described above, the embodiment of the present invention has been described. However, the present invention is not limited to the above-described embodiment, and various modifications are possible. For example, when the inner ring 24 is formed by cold rolling or the like, the large diameter The side edge may be bent in the outer diameter direction. Further, in the wheel bearing device shown in FIG. 1, the pilot part (the large diameter first part 115a and the small diameter second part 115b) as shown in FIG. A pilot portion may be formed. In the above embodiment, the rolling element as the torque transmission means of the bearing 2 is configured by the ball 30, but a tapered roller may be used.

It is a longitudinal cross-sectional view of the wheel bearing apparatus which shows 1st Embodiment of this invention. It is a longitudinal cross-sectional view of the state where the bearing of the wheel bearing device is press-fitted into a knuckle. It is explanatory drawing of the shaping | molding method of the outer ring | wheel of the bearing of the said bearing apparatus for wheels. It is explanatory drawing of the shaping | molding method of the inner ring | wheel of the bearing of the said bearing apparatus for wheels. It is a longitudinal cross-sectional view of the wheel bearing apparatus which shows 2nd Embodiment of this invention. It is a longitudinal cross-sectional view of the conventional wheel bearing apparatus.

Explanation of symbols

N knuckle 1 hub wheel 2 bearing 3 constant velocity universal joint 24 inner ring 25 outer rings 26 and 27 outer rolling surfaces 28 and 29 inner rolling surface 30 rolling element 50a knuckle fitting surface 53 bulging portion

Claims (8)

  An outer ring having a double row outer raceway formed on the inner periphery, a pair of inner rings having an inner raceway facing the outer raceway surface of the outer ring on the outer periphery, and the outer raceway and inner ring of the outer ring. A bearing device for a wheel comprising a double row rolling element that is rotatably accommodated between the inner raceway and at least an outer ring formed by cold rolling, and the outer ring, inner ring, rolling element A wheel bearing device, wherein the moving body is integrated into the hub wheel by press fitting in an assembled state.   The circumferential recess is provided in the axial central portion of the outer diameter surface of the outer ring by providing a bulging portion that bulges toward the inner diameter side in the axial central portion of the inner diameter surface of the outer ring. Wheel bearing device described in 1.   The wheel bearing device according to claim 1, wherein the inner ring is made of cold rolling or a press plate.   2. The wheel bearing device according to claim 1, wherein a preload is applied to the inner ring of the rolling bearing press-fitted into the hub ring by crimping the end of the hub ring.   2. The wheel bearing device according to claim 1, wherein the outer ring is subjected to hardened steel cutting by cutting after heat treatment after cold rolling forming. 3.   The wheel bearing device according to claim 1, wherein a fitting surface is formed on an outer diameter surface of the outer ring, and the fitting surface is press-fitted into a knuckle.   The wheel bearing device according to any one of claims 1 to 6, wherein the wheel bearing device is used for a drive wheel.   The wheel bearing device according to any one of claims 1 to 6, wherein the wheel bearing device is used for a driven wheel.

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