JP2010230079A - Bearing for wheel and bearing device for wheel having the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bearing for a wheel, and the bearing device for the wheel having the same, in which the wall thickness of an inner ring is optimized to reduce the weight, size and cost of the device, and the durability of the bearing is increased. <P>SOLUTION: A connection section 27 between an annular recess 25 and an outer diameter surface 10b of an outer member 10 is formed in a circular arc shape substantially concentric with the curvature center of each outer rolling surface 10a to form the wall thickness of the outer member 10 substantially uniform by cold rolling from a pipe material, and a connection section 29 between an inner diameter surface 11d of the inner ring 11 and a shoulder section 28 is formed in a circular arc shape substantially concentric with the curvature center of an inner rolling surface 11a to make the wall thickness of the inner ring 11 substantially uniform by cold rolling from the pipe material. The wall thickness Tmi of a bottom groove section of the inner rolling surface 11a is set to be greater than the wall thickness Tmo of the bottom groove section of the outer rolling surface 10a (Tmi≥Tmo), and the wall thickness Ti of the inner ring 11 in the direction of contact angle α is set to be greater than the wall thickness To in the direction of contact angle α of the outer member 10 (Ti≥To). <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a wheel bearing for rotatably supporting a wheel of a vehicle such as an automobile, and more particularly, to a wheel bearing for reducing the weight, size and cost, and improving the durability of the bearing. The present invention relates to a wheel bearing device provided.

  2. Description of the Related Art Conventionally, a wheel bearing device for supporting a wheel of an automobile or the like supports a hub wheel for mounting a wheel rotatably via a double row rolling bearing, and includes a drive wheel and a driven wheel. For structural reasons, an inner ring rotation method is generally used for driving wheels, and both an inner ring rotation method and an outer member rotation method are generally used for driven wheels. This 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, and is an outer member. 2nd generation structure with body mounting flange or wheel mounting flange formed directly on the outer periphery of the wheel, 3rd generation structure with one inner rolling surface formed directly on the outer periphery of the hub wheel, or constant speed with the hub wheel 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 universal joint.

  Conventionally, what is shown in FIG. 6 is known as a wheel bearing composed of a general first generation angular contact ball bearing (see, for example, Patent Document 1). The wheel bearing 50 includes an outer member 51 in which a double-row arc-shaped outer rolling surface 51a is integrally formed on the inner periphery, and an arc-shaped shape facing the double-row outer rolling surfaces 51a and 51a on the outer periphery. A pair of inner rings 52, 52 formed with an inner rolling surface 52 a, and a double row of balls accommodated between the rolling surfaces of the inner ring 52 and the outer member 51 via a retainer 53. 54, 54, and the small-diameter side end faces 52b, 52b of the inner ring 52 abut each other in a butted state to constitute a back-to-back type double row angular ball bearing. Seals 55, 55 are attached to both ends of the outer member 51, and are in sliding contact with the outer diameter of the inner ring 52. Leakage of grease sealed inside the bearing and foreign matter such as rainwater and dust from the outside. It prevents entry into the bearing.

  Moreover, the wheel bearing which consists of an angular ball bearing reduced in weight as shown in FIG. 7 is also known (for example, refer patent document 2). In this wheel bearing 59, the outer member 60 and the inner ring 61 are formed by cold rolling from a pipe material, the outer diameter of the outer member 60 is recessed at the center, and an annular recess 56 is formed. An annular convex portion 57 is formed on the surface. The radius of curvature R of the connecting portion between the outer diameter of the outer member 60 and the annular recess 56 is formed in an arc shape in the range of R = 1.5 to 1.8 Rw when the radius of the ball 54 is Rw. This part is set to a substantially uniform thickness. As a result, it is possible to prevent the shoulder 58 from cracking, and to prevent the contact ellipse of the ball 54 from riding on the shoulder 58 when a turning moment is applied, thereby preventing an edge load from being generated. Can be improved. Here, the edge load is an excessive stress concentration generated at a corner or the like, and refers to an event that becomes one of the factors of early peeling.

JP 2007-120771 A JP 2008-256073 A

  In such wheel bearings 50 and 59, the groove radius of curvature of the outer rolling surface 51a of the outer members 51 and 60 is set larger than that of the inner rolling surface 52a of the inner rings 52 and 61. The contact condition between the inner raceway surface 52a and the ball 54, which are in contact with each other, is stricter than the contact between the outer raceway surface 51a and the ball 54, and the contact surface pressure generated when the vehicle travels is The inner rings 52 and 61 are higher than the outer members 51 and 60.

  However, in the wheel bearing 59, since the outer member 60 and the inner ring 61 are formed to have substantially the same thickness, the inner ring 61 is more likely to be damaged first. Here, the thickness of the inner ring 61 may be increased as a whole to increase the strength and rigidity. However, this is not preferable because it goes against weight reduction and causes a decrease in workability and accuracy.

  The present invention has been made in view of the above circumstances, and is designed to optimize the thickness of the inner ring so as to reduce the weight, reduce the cost and reduce the cost, and improve the durability of the bearing. And it aims at providing the bearing device for wheels provided with this.

  In order to achieve such an object, the invention according to claim 1 of the present invention includes an annular protrusion projecting radially inward on the inner periphery, and double-row arc-shaped outer rolls on both sides of the annular protrusion. An outer member in which an annular recess is formed from a pipe material by plastic working in a central portion of the outer periphery, an arc-shaped inner rolling surface facing the outer surface of the double row on the outer periphery, A pair of inner rings in which a cylindrical shoulder extending in the axial direction from the outer diameter side of the inner rolling surface is formed by plastic working from a pipe material, and a cage between both inner rings and the rolling surfaces of the outer member And a double row of balls accommodated so as to be freely rollable through the outer raceway, the radius of curvature of the outer raceway surface being set larger than the radius of curvature of the inner raceway surface, For wheel bearings that make a back-to-back type double row angular contact ball bearing in a butted state A connecting portion between the outer diameter surface of the outer member and the annular recess is formed in an arc shape having a predetermined curvature radius substantially concentric with the center of curvature of the outer rolling surface, and the outer member has a substantially uniform thickness. The inner ring surface of the inner ring and the connecting portion of the shoulder is formed in an arc shape substantially concentric with the center of curvature of the inner rolling surface, the inner ring is set to a substantially uniform thickness, The thickness Tmi of the groove bottom portion of the inner rolling surface is set to be larger than the thickness Tmo of the groove bottom portion of the outer rolling surface (Tmi ≧ Tmo).

  Thus, the outer member and the pair of inner rings are formed from the pipe material by plastic working, and the outer member has an annular protrusion protruding radially inward on the inner periphery, and double rows on both sides of the annular protrusion. An arc-shaped outer rolling surface, an annular recess is formed in the central portion of the outer periphery, and the inner ring has an arc-shaped inner rolling surface that faces the double-row outer rolling surface on the outer periphery, and the inner rolling surface. A back-to-back type double-row angular contact ball with a cylindrical shoulder extending in the axial direction from the outer diameter side of the running surface, with the radius of curvature of the outer rolling surface set to be larger than the radius of curvature of the inner rolling surface In the wheel bearing constituted by the bearing, the outer diameter surface of the outer member and the connecting portion of the annular recess are formed in an arc shape having a predetermined radius of curvature substantially concentric with the center of curvature of the outer rolling surface. The member is set to a substantially uniform wall thickness, and the inner ring surface of the inner ring and the shoulder joint are curved on the inner rolling surface. It is formed in a circular arc shape substantially concentric with the center, the inner ring is set to a substantially uniform thickness, and the thickness Tmi of the groove bottom portion of the inner rolling surface is larger than the thickness Tmo of the groove bottom portion of the outer rolling surface ( (Tmi ≧ Tmo) is set so that the thickness of the inner ring is optimized to reduce the weight, reduce the cost, and improve the durability of the bearing. be able to.

  Preferably, as in the invention described in claim 2, the thickness Ti of the inner ring in the contact angle direction is set to be thicker than the thickness To of the outer member in the contact angle direction (Ti ≧ To). If so, it is possible to improve the strength and durability of the inner ring, which has a higher surface pressure than the outer member, and to improve the durability of the bearing.

  Further, as in the invention described in claim 3, the thickness To in the contact angle direction of the outer member is set to be larger than the thickness Tmo of the groove bottom portion of the outer rolling surface (To ≧ Tmo). At the same time, if the thickness Ti in the contact angle direction of the inner ring is set to be larger than the thickness Tmi of the groove bottom portion of the inner rolling surface (Ti ≧ Tmi), the strength and rigidity can be reduced while achieving weight reduction. Can be improved.

  Further, as in the invention described in claim 4, when the radius of curvature Rmo of the connecting portion of the outer member is Rw = Rw = 1.5 to 1.8Rw when the radius of the ball is Rw. If it is set to, the wall thickness is reduced and the rigidity is not lowered, and the wall thickness is increased and the workability of plastic working is not lowered.

  If the outer member and the inner ring are formed by cold rolling as in the invention described in claim 5, the thickness can be made substantially uniform, and the shape and dimensions are predetermined. Accuracy can be ensured.

  In the invention according to claim 6 of the present invention, a wheel mounting flange is integrally formed at one end portion, and a cylindrical small-diameter step portion extending in the axial direction from the wheel mounting flange via the shoulder portion is formed. A hub wheel and a wheel bearing according to any one of claims 1 to 5 press-fitted into a small-diameter step portion of the hub wheel through a predetermined squeeze and fitted into a knuckle. The outer joint member of the constant velocity universal joint is fitted through the serration, the pair of inner rings are sandwiched between the shoulder part of the hub wheel and the shoulder part of the outer joint member, and a predetermined bearing preload is applied. .

  Thus, a hub wheel integrally having a wheel mounting flange at one end portion and formed with a cylindrical small diameter step portion extending in the axial direction from the wheel mounting flange via a shoulder portion, and a small diameter step of the hub wheel And a wheel bearing that is press-fitted into a portion through a predetermined squeeze and fitted into a knuckle, and an outer joint member of a constant velocity universal joint is fitted into the hub wheel via a serration, and the pair of inner rings is a hub. The wheel bearing for the drive wheel that is sandwiched between the shoulder of the wheel and the shoulder of the outer joint member and given a predetermined bearing preload, increases the strength and rigidity of the bearing and improves the rolling fatigue life. An apparatus can be provided.

  Further, as in the invention described in claim 7, a space is provided between the outer member and the knuckle on the line of action in the contact angle direction of the outer member, and / or the contact angle of the inner ring. If a space is provided between the inner ring and the small-diameter step portion of the hub ring on the directional action line, the weight can be reduced.

  Further, as in the invention according to claim 8, the fitting width A between the inner diameter surface of the inner ring and the small-diameter step portion of the hub wheel is an intersection between the extension of the inner diameter surface and the action line in the contact angle direction. If it is set to be smaller than the distance B and larger than the pitch P of the double row balls (P <A <B), it is possible to prevent creep between the hub ring and the inner ring while reducing the weight. A sufficient fitting force can be ensured.

  The wheel bearing according to the present invention has an annular protrusion protruding radially inward on the inner periphery, a double-row arc-shaped outer rolling surface on both sides of the annular protrusion, and a recess in the center of the outer periphery. And an annular recess formed by plastic working from a pipe material, an arcuate inner rolling surface facing the outer rolling surface of the double row on the outer periphery, and an outer diameter side of the inner rolling surface A cylindrical shoulder extending in the axial direction from a pair of inner rings formed by plastic processing from a pipe material, and accommodated in a freely rollable manner via a cage between the inner ring and both rolling surfaces of the outer member. A plurality of rows of balls, a radius of curvature of the outer raceway surface is set to be larger than a radius of curvature of the inner raceway surface, and a small-diameter side end face of the inner race abuts in a butted state. In a wheel bearing constituting a double row angular contact ball bearing of a matching type, the outer diameter surface of the outer member and the front The connecting portion of the annular recess is formed in an arc shape having a predetermined curvature radius that is substantially concentric with the center of curvature of the outer rolling surface, and the outer member is set to have a substantially uniform thickness, and the inner diameter of the inner ring The connecting portion between the surface and the shoulder is formed in an arc shape substantially concentric with the center of curvature of the inner rolling surface, the inner ring is set to a substantially uniform thickness, and the thickness of the groove bottom portion of the inner rolling surface Since Tmi is set to be larger than the wall thickness Tmo of the groove bottom portion of the outer rolling surface (Tmi ≧ Tmo), the inner wall thickness is optimized to reduce weight, size and cost. In addition, it is possible to provide a wheel bearing in which the durability of the bearing is improved.

It is a longitudinal section showing one embodiment of a wheel bearing device concerning the present invention. It is an enlarged view which shows the wheel bearing of FIG. (A) is a longitudinal cross-sectional view which shows the outer member single-piece | unit of FIG. 2, (b) is a longitudinal cross-sectional view which shows a single inner ring same as the above. It is a principal part enlarged view which shows the thickness relationship of the outer member of FIG. 2, and an inner ring | wheel. It is explanatory drawing which shows the manufacturing process of the outward member which concerns on this invention. It is a longitudinal cross-sectional view which shows the conventional wheel bearing. It is a longitudinal cross-sectional view which shows the other conventional wheel bearing.

  An annular projection protruding radially inward on the inner periphery, a double-row arc-shaped outer rolling surface on both sides of the annular projection, and an annular recess in the center of the outer periphery are cold rolled from the pipe material. An outer member formed by machining, an arc-shaped inner rolling surface facing the outer rolling surface of the double row on the outer periphery, and a cylindrical shoulder extending in the axial direction from the outer diameter side of the inner rolling surface A pair of inner rings formed by cold rolling from a pipe material, and a double row of balls accommodated between the rolling surfaces of the inner ring and the outer member via a cage. A radius of curvature of the outer rolling surface is set to be larger than a radius of curvature of the inner rolling surface, and the end surfaces on the small diameter side of the inner ring abut each other in a butted state. In the wheel bearing constituting the angular ball bearing, the outer diameter surface of the outer member and the annular recess The connecting portion is formed in an arc shape having a predetermined radius of curvature substantially concentric with the center of curvature of the outer rolling surface, and the outer member is set to a substantially uniform thickness, and the inner diameter surface of the inner ring and the The connecting portion of the shoulder is formed in an arc shape substantially concentric with the center of curvature of the inner rolling surface, the inner ring is set to a substantially uniform thickness, and the thickness Tmi of the groove bottom portion of the inner rolling surface is The wall thickness Tmo of the groove bottom portion of the outer rolling surface is larger (Tmi ≧ Tmo), and the wall thickness Ti in the contact angle direction of the inner ring is larger than the wall thickness To in the contact angle direction of the outer member (Ti ≧ To) is set.

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 showing the wheel bearing of FIG. 1, and FIG. 3 (a) is an outer member of FIG. FIG. 4 is a longitudinal sectional view showing a single body, FIG. 4 is a longitudinal sectional view showing a single inner ring of FIG. 2, FIG. 4 is an enlarged view of a main part showing a thickness relationship between the outer member and the inner ring of FIG. It is explanatory drawing which shows the manufacturing process of the outward member which concerns on this invention. 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 has a first generation structure, and includes a hub wheel 1 and a wheel bearing 2 attached to the hub wheel 1. A constant velocity universal joint 3 is fitted into the hub wheel 1 so as to be able to transmit torque, and the hub wheel 1 and the constant velocity universal joint 3 are detachably integrated via a fixing nut 4.

  The hub wheel 1 has a wheel mounting flange 5 for mounting a wheel (not shown) at one end portion on the outer side, and a cylindrical shape extending from the wheel mounting flange 5 to the outer periphery in the axial direction via a shoulder portion 1a. A small-diameter step portion 1b is formed, and a serration (or spline) 1c for torque transmission is formed on the inner periphery. Hub bolts 5a that fasten the wheels are planted at equal intervals in the circumferential direction of the wheel mounting flanges 5. The hub wheel 1 is made of medium and high carbon steel containing 0.40 to 0.80 wt% of carbon such as S53C, and is not heat-treated after forging, and the structure remains raw. In addition, a method of performing a tempering treatment after forging in order to increase the fatigue strength with respect to the bending strength, or a surface hardness of 50 to 64 HRC by induction hardening from the shoulder portion 1a to the small diameter step portion 1b. May be.

  The constant velocity universal joint 3 includes an outer joint member 6, a joint inner ring (not shown), a cage, and a torque transmission ball. The outer joint member 6 integrally includes a cup-shaped mouth portion 7, a shoulder portion 8 that is a bottom portion of the mouth portion 7, and a shaft portion 9 that extends from the shoulder portion 8 in the axial direction. A serration 9 a that engages with the serration 1 c of the hub wheel 1 and an external thread 9 b are formed at the end of the serration 9 a on the outer periphery of the shaft portion 9.

  The wheel bearing 2 includes an outer member 10, a pair of inner rings 11, 11, and double rows of balls 12, 12 accommodated between the two members, and the outer member 10 is attached to a knuckle 13 constituting a suspension device. While being fitted, the pair of inner rings 11 and 11 are press-fitted into the small-diameter step portion 1b of the hub wheel 1 through a predetermined scissors. The small-diameter side (front side) end faces 11b, 11b of the inner rings 11, 11 are abutted in a butted state to constitute a so-called back-to-back type double row angular ball bearing.

  Further, the outer joint member 6 is internally fitted to the hub wheel 1 through the serrations 1c and 9a until the shoulder portion 8 of the outer joint member 6 abuts on the large-diameter side (rear) end surface 11c of the inner ring 11, and a pair of The inner rings 11 and 11 are fixed in a state of being sandwiched between the shoulder 1 a of the hub wheel 1 and the shoulder 8 of the outer joint member 6. Further, a predetermined bearing preload is applied to the male screw 9b by tightening the fixing nut 4 with a predetermined tightening torque. As a result, it is possible to provide a wheel bearing device for a drive wheel in which the bearing rigidity is increased and the rolling fatigue life of the bearing is improved.

  As shown in an enlarged view in FIG. 2, the wheel bearing 2 is formed with double-row arc-shaped outer rolling surfaces 10 a and 10 a on the inner periphery of the outer member 10, and the pair of inner rings 11 and 11. Arc-shaped inner rolling surfaces 11a and 11a are formed on the outer periphery so as to face these double-row outer rolling surfaces 10a and 10a, respectively. A double row of balls 12 and 12 are accommodated between the rolling surfaces via the cages 14 and 14 so as to roll freely, and an annular space formed between the outer member 10 and the inner ring 11 is accommodated. Seals 15 and 16 are attached to the openings to prevent leakage of grease sealed inside the bearing and foreign matters such as rainwater and dust from entering the bearing from the outside.

  The outer-side seal 15 is integrally joined to a cored bar 18 that is press-fitted into a cylindrical fitting part 17 formed at both ends of the outer member 10, and vulcanized and bonded to the cored bar 18. An integrated seal composed of a seal member 19 made of synthetic rubber such as rubber is formed. The core 18 has a substantially L-shaped cross-section by pressing an austenitic stainless steel plate (JIS standard SUS304, etc.) or a rust-proof cold rolled steel plate (JIS standard SPCC, etc.). Is formed. Further, the seal member 19 includes a pair of radial lips 19a and 19b that are slidably contacted with the outer diameter of the inner ring 11 via a predetermined shimoshiro.

  The inner-side seal 16 constitutes a so-called pack seal including an annular seal plate 20 and a slinger 21 having a substantially L-shaped cross section. The seal plate 20 includes a metal core 22 that is press-fitted into the fitting portion 17 of the outer member 10, and a seal member 23 that is integrally vulcanized and bonded to the metal core 22. The metal core 22 has a substantially L-shaped cross section by pressing an austenitic stainless steel plate (JIS standard SUS304, etc.) or a rust-proof cold rolled steel plate (JIS standard SPCC, etc.). Is formed. Further, the seal member 23 includes a side lip 23a extending obliquely outward in the radial direction, a grease lip 23b and an intermediate lip 23c formed in a bifurcated shape.

  On the other hand, the slinger 21 is composed of an austenitic stainless steel plate (JIS standard SUS304 type or the like), a ferritic stainless steel plate (JIS standard SUS430 type or the like), or a rust-proof cold rolled steel plate (JIS standard type). SPCC system etc.) is formed by pressing and has a substantially L-shaped cross section, and a cylindrical portion 21a that is press-fitted into the outer diameter of the inner ring 11, and a vertical plate portion 21b that extends radially outward from the cylindrical portion 21a. Become. The side lip 23a of the seal member 23 is slidably contacted with the upright plate portion 21b, and the grease lip 23b and the intermediate lip 23c are respectively slidably contacted with the cylindrical portion 21a.

  Here, the outer member 10 and the inner ring 11 are formed by pressing or cold rolling (hereinafter referred to as plastic working) a pipe material made of bearing steel such as SUJ2 or carburized steel such as SCr420 or SCM415. . Specifically, as shown in FIG. 5A, a billet 31 cut to a predetermined size from a steel bar 30 is formed into a pipe material 32 as a material by hot forging and turning, or (b ), The steel pipe 33 is cut into a predetermined dimension and formed into a pipe material 34 as a material. In the case where the pipe members 32 and 34 manufactured in such a process are the outer member 10 as shown in (c), the inner peripheral mold 35 and the outer peripheral mold 35 are inserted in the outer peripheral mold 35. The pipe members 32 and 34 are formed into a predetermined shape and size by being sandwiched between the molds 36 and moving the molds 35 and 36 while rotating in opposite directions. Here, the pipe materials 32 and 34 used as the material are thinned by the two molds 35 and 36, and accordingly, rolled in the width direction, but both end surfaces are regulated by the flange 36 a of the outer peripheral mold 36. Thus, the outer member 10 with higher accuracy can be manufactured.

  In the case of SUJ2, the core is hardened in the range of 58 to 64 HRC by submerged quenching or induction quenching. In the case of carburized steel, the surface hardness is hardened to a range of 58 to 64 HRC by carburizing and quenching. Other examples of the material of the outer member 10 and the inner ring 11 include stainless steel such as SUS440C and carbon steel such as S53C.

  On the other hand, in the case of carbon steel, at least in the outer member 10, the double row outer rolling surfaces 10a, 10a are subjected to a hardening process within a range of 58 to 64 HRC by overall heating by induction hardening, In No. 11, the inner rolling surface 11a is subjected to a hardening process in a range of 58 to 64 HRC by surface heating by induction hardening. And these both rolling surfaces 10a and 11a are formed with a predetermined | prescribed dimension and precision by grinding, and super-finishing is given as needed after that.

Next, the configuration of the outer member 10 and the inner ring 11 will be described in detail with reference to FIG.
As shown in (a), the outer member 10 is formed by forming an annular projection 24 projecting radially inward from the pipe material used as a raw material to the inner circumference, and double rows on both sides of the annular projection 24. Arc-shaped outer rolling surfaces 10a and 10a are formed, and fitting portions 17 and 17 of seals 15 and 16 are formed at both ends. And the fitting part 17 including the outer rolling surfaces 10a and 10a of the double row is formed with predetermined dimensions and accuracy by grinding after the heat treatment after plastic working. Note that both end faces where burrs are generated by plastic working are turned after machining, and further subjected to grinding after heat treatment if necessary. As a result, productivity is improved, yield is improved, cost can be reduced, and accuracy and sealing performance equivalent to those of conventional bearings can be secured.

  Here, in order to appropriately secure the shoulder height of the annular convex portion 24 from the outer rolling surface 10a, the inner diameter of the annular convex portion 24 is formed flat during plastic processing of the outer member 10, and the outer side The central portion of the member 10 is recessed radially inward to form an annular recess 25 so that the shoulder 26 is filled with the material. Here, the annular recess 25 is provided with a space between the outer member 10 and the knuckle 13 on the line of action in the contact angle direction of the outer member 10.

  On the other hand, as shown in (b), the inner ring 11 is formed by plastic processing from a pipe material as a raw material, and an arcuate inner rolling surface 11a on the outer periphery, and from the outer diameter side of the inner rolling surface 11a in the axial direction. An extending cylindrical shoulder portion 28 is formed, and a connecting portion 29 between the inner diameter surface 11d of the inner ring 11 and the shoulder portion 28 is formed in an arc shape so that the shoulder portion 28 is filled with a material. Here, the shoulder portion 28 becomes a fitting surface of the seal land portion of the outer side seal 15 and the inner side seal 16 and is ground by a general grinding wheel simultaneously with the inner rolling surface 11a after heat treatment after plastic working. , Formed with predetermined dimensions and accuracy. As with the outer member 10, both end faces where burrs are generated by plastic working are turned after machining, and further subjected to grinding after heat treatment as necessary. As a result, productivity is improved, yield is improved, cost can be reduced, and accuracy and sealing performance equivalent to those of conventional bearings can be secured. The connecting portion 29 is provided with a space between the inner ring 11 and the small-diameter step portion 1 b of the hub wheel 1 on the line of action in the contact angle direction of the inner ring 11.

  Further, as shown in FIG. 4 in an enlarged manner, a connecting portion 27 between the outer diameter surface 10b of the outer member 10 and the annular recess 25 is formed in an arc shape having a curvature radius Rmo, and the connecting portion 27 and the curvature radius Ro. Is set so that the center of curvature of the outer rolling surface 10a is substantially the same position, and when the radius of the ball 12 is Rw, the radius of curvature Rmo is set to a range of 1.5 to 1.8 Rw. Has been. As a result, the thickness of this portion can be formed substantially evenly, and the shoulder 26 can be prevented from cracking, and the contact ellipse of the ball 12 rides on the shoulder 26 when a turning moment is applied, and the edge load is reduced. It can be prevented from occurring.

  When the radius of curvature Rmo of the connecting portion 27 is smaller than 1.5 times the radius Rw of the ball 12, the thickness is reduced and the rigidity is reduced, so that it cannot withstand the stress during moment loading. If it exceeds 1.8 times of Rw, not only will the wall thickness increase and the workability of plastic working will decrease, but the shape will not greatly differ from conventional forged products, and it will not contribute to light weight and compactness in general. It is. As a result, the thickness of this portion can be formed substantially evenly, and the shoulder 26 can be prevented from cracking, and the contact ellipse of the ball 12 rides on the shoulder 26 when a turning moment is applied, and the edge load is reduced. It can be prevented from occurring.

  Further, the connecting portion 29 of the inner ring 11 is formed in an arc shape having a radius of curvature Rmi, and the connecting portion 29 and the center of curvature of the inner raceway surface 11a having the radius of curvature Ri are set to be substantially the same position. Yes. As a result, the thickness of this portion can be formed substantially uniformly, and cracks can be prevented from occurring in the shoulder portion 28, and the contact ellipse of the ball 12 rides on the shoulder portion 28 when a turning moment is applied, so that the edge load is reduced. It can be prevented from occurring.

  Here, substantially equal means that the thickness of the pipe material before molding is uniform, and the connecting portions 27 and 29 also have a shape obtained as a result of molding without plastic flow other than the purpose of forming an arc. It means a state of thickness, and includes a state of being slightly thinner or thicker due to displacement of the material thickness when forming the arcs of the connecting portions 27 and 29.

  Generally, the inner raceway surface of the inner ring is different from the outer raceway surface of the outer member, and the radius of curvature of the inner raceway surface of the inner ring is set smaller than the radius of curvature of the outer raceway surface of the outer member. However, the contact surface pressure received by each rolling surface during turning of the vehicle is such that the inner rolling surface of the inner ring is in a contact state between the ball and the convex, so that the inner ring is higher than the outer member. Therefore, in particular, when thin inner rings and outer members are used, the contact surface pressure that each rolling surface receives during turning travels in the contact angle direction on the outer diameter side of the outer member and the inner diameter side of the inner ring. The stress on the line must be below the critical value for failure.

  Here, in this embodiment, as shown in FIG. 4, in the inner ring 11 having such strength, the thickness Ti in the contact angle α direction of the inner ring 11 is changed to the thickness Ti in the contact angle α direction of the outer member 10. It is set to be thicker than To (Ti ≧ To). As a result, the strength and durability of the inner ring 11 having a higher surface pressure than the outer member 10 can be improved, and the wheel is designed to be lighter, more compact, lower in cost, and improved in durability of the bearing. A bearing 2 can be provided.

  Also, in the thicknesses Tmo and Tmi of the groove bottom portions of the outer member 10 and the inner ring 11, the thickness Tmi of the groove bottom portion of the inner ring 11 is set to be thicker than the thickness Tmo of the groove bottom portion of the outer member 10. (Tmi ≧ Tmo). Thereby, the breaking strength of the inner ring | wheel 11 can be raised and durability can be improved. In this type of thin-walled outer member 10 and inner ring 11, the thicknesses To and Ti in the contact angle direction are more dominant in terms of strength than the wall thicknesses Tmo and Tmi at the groove bottoms of the rolling surfaces 10a and 11a. Therefore, the thickness To of the outer member 10 in the contact angle α direction is set to be larger than the thickness Tmo of the groove bottom (To ≧ Tmo). Similarly, the thickness Ti in the contact angle α direction of the inner ring 11 is set to be larger than the thickness Tmi of the groove bottom (Ti ≧ Tmi). Thereby, strength and rigidity can be improved while achieving weight reduction.

  Furthermore, in this embodiment, as shown in FIG. 2, the fitting width A between the inner diameter surface 11d of the inner ring 11 and the small diameter step portion 1b of the hub wheel 1 is such that the extension of the inner diameter surface 11d and the action line in the contact angle α direction. Is set to be smaller than the distance B between the intersections and larger than the pitch P of the double row balls 12 of the wheel bearing 2. Thereby, it is possible to secure a sufficient fitting force to prevent creep between the hub wheel 1 and the inner ring 11 while reducing the weight. Here, creep refers to a phenomenon in which the bearing surface slightly moves in the circumferential direction due to a lack of mating squealing or poor mating surface processing accuracy, and the mating surface becomes a mirror surface, and in some cases, seizure or welding occurs with galling. .

  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 generation structure including a hub wheel integrally having a wheel mounting flange at one end and a pair of inner rings press-fitted into the hub wheel. .

DESCRIPTION OF SYMBOLS 1 Hub wheel 1a, 8, 26, 28 Shoulder part 1b Small diameter step part 1c, 9a Serration 2 Wheel bearing 3 Constant velocity universal joint 4 Fixing nut 5 Wheel mounting flange 5a Hub bolt 6 Outer joint member 7 Mouse part 9 Shaft part 9b Male thread DESCRIPTION OF SYMBOLS 10 Outer member 10a Outer rolling surface 10b Outer member outer diameter surface 11 Inner ring 11a Inner rolling surface 11b Small diameter side end surface 11c Large diameter side end surface 11d Inner ring inner diameter surface 12 Ball 13 Knuckle 14 Cage 15 Outer side seal 16 Inner side seal 17 Fitting part 18, 22 Core metal 19, 23 Seal member 19a, 19b Radial lip 20 Seal plate 21 Slinger 21a Cylindrical part 21b Standing plate part 23a Side lip 23b Grease lip 23c Intermediate lip 24 Annular convex part 25 Annular recesses 27, 29 Connecting portion 30 Steel bar 31 Billet 32, 34 Pipe material 33 Pipe 35 Inner peripheral mold 36 Outer peripheral mold 36a 鍔 part 50, 59 Wheel bearing 51, 60 Outer member 51a Outer rolling surface 52, 61 Inner ring 52a Inner rolling surface 52b Small diameter side end surface 53 Cage 54 Ball 55 Seal 56 Annular recessed part 57 Annular convex part 58 Shoulder part A Fitting width B with the fitting part of the inner ring P Distance between the intersections of the line of contact in the contact angle direction and the fitting part P Double-row pitch R, Rmo Outer member Radius of curvature Ro of outer rolling surface Ri Radius of inner rolling surface Rw Ball radius Ti Thickness of inner ring contact angle direction Th Thickness of outer member contact angle direction Tmi Inner ring groove Thickness Tmo of bottom part Thickness α of groove part of outer member Contact angle

Claims (8)

An annular projection protruding radially inward on the inner circumference, a double-row arc-shaped outer rolling surface on both sides of the annular projection, and an annular depression formed in the center of the outer circumference by plastic working An outer member formed,
An arcuate inner rolling surface facing the outer rolling surface of the double row on the outer periphery and a cylindrical shoulder extending in the axial direction from the outer diameter side of the inner rolling surface are formed by plastic working from the pipe material A pair of inner rings,
These inner rings and double rows of balls accommodated between the rolling surfaces of the outer member via a cage to be freely rollable,
The radius of curvature of the outer rolling surface is set larger than the radius of curvature of the inner rolling surface,
In the wheel bearing that the end surface on the small diameter side of the inner ring abuts in a butted state and constitutes a back-to-back type double row angular contact ball bearing,
A connecting portion between the outer diameter surface of the outer member and the annular recess is formed in an arc shape having a predetermined curvature radius substantially concentric with the center of curvature of the outer rolling surface, and the outer member has a substantially uniform thickness. The inner ring surface of the inner ring and the connecting portion of the shoulder is formed in an arc shape substantially concentric with the center of curvature of the inner rolling surface, the inner ring is set to a substantially uniform thickness, A wheel bearing, wherein a thickness Tmi of a groove bottom portion of the inner rolling surface is set to be larger than a thickness Tmo of a groove bottom portion of the outer rolling surface (Tmi ≧ Tmo).   2. The wheel bearing according to claim 1, wherein a thickness Ti of the inner ring in the contact angle direction is set to be larger than a thickness To of the outer member in the contact angle direction (Ti ≧ To).   A thickness To in the contact angle direction of the outer member is set to be greater than a thickness Tmo of the groove bottom portion of the outer rolling surface (To ≧ Tmo), and a thickness Ti in the contact angle direction of the inner ring is set to The wheel bearing according to claim 1, wherein the wheel bearing is set to be larger than a wall thickness Tmi of the groove bottom portion of the inner rolling surface (Ti ≧ Tmi).   The curvature radius Rmo of the joint portion of the outer member is set to be in a range of Rmo = 1.5 to 1.8 Rw, where Rw is the radius of the ball. The wheel bearing described.   The wheel bearing according to claim 1, wherein the outer member and the inner ring are formed by cold rolling.   A hub ring integrally having a wheel mounting flange at one end and a cylindrical small diameter step portion extending in an axial direction from the wheel mounting flange via a shoulder portion, and a predetermined diameter on the small diameter step portion of the hub ring. A wheel bearing according to any one of claims 1 to 5 that is press-fitted through a nip and is fitted into a knuckle, and an outer joint member of a constant velocity universal joint is fitted into the hub wheel via a serration, The wheel bearing device according to claim 1, wherein the pair of inner rings are sandwiched between a shoulder portion of the hub wheel and a shoulder portion of the outer joint member, and a predetermined bearing preload is applied.   On the line of action in the contact angle direction of the outer member, a space is provided between the outer member and the knuckle, and / or on the line of action in the contact angle direction of the inner ring, the inner ring and the hub ring The wheel bearing device according to claim 6, wherein a space is provided between the small-diameter step portion.   The fitting width A between the inner diameter surface of the inner ring and the small-diameter step portion of the hub ring is smaller than the distance B between the intersection of the extension of the inner diameter surface and the action line in the contact angle direction, and the double row balls The wheel bearing device according to claim 6 or 7, wherein the wheel bearing device is set to be larger than the pitch P (P <A <B).

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