WO2014054719A1

WO2014054719A1 - Wheel bearing device

Info

Publication number: WO2014054719A1
Application number: PCT/JP2013/076908
Authority: WO
Inventors: 洋斗須間; 智哉山田
Original assignee: Ntn株式会社
Priority date: 2012-10-04
Filing date: 2013-10-03
Publication date: 2014-04-10
Also published as: JP6054124B2; JP2014074448A

Abstract

[Problem] To provide a wheel bearing device that is lightweight and compact while maintaining the desired strength/rigidity. [Solution] A wheel bearing device for which the pitch circle diameter (PCDo) of rolling elements (3) on the outer side is set greater than the pitch circle diameter (PDCi) of rolling elements (3) on the inner side, wherein multiple attachment parts (17) are formed protruding radially outward from the outer circumferential surface (24) of an inner-side end part and extending in the axial direction, and the mold dividing position (A) of an outside member (2) in a forging die is set close to the outside rolling surface (2a) that is on the outer side of multiple rows of outside rolling surfaces (2a, 2b). In addition, the outer circumferential surface (22) on the inner side of the outside member (2) forms a tapered surface which has a prescribed angle of inclination (θ1) and the diameter of which decreases toward the outer side from the mold dividing position (A) via a shoulder part (23), and the outer circumferential surface (25) on the inner side is formed with protruding surfaces (25a), which form a tapered ridge line having a prescribed angle of inclination (θ2) and form the outer circumferential surface of the attachment parts (17), and recessed surfaces (25b), which smoothly connect these protruding surfaces (25a).

Description

Wheel bearing device

BACKGROUND OF THE INVENTION 1. Field of the Invention 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 is light and compact while ensuring desired strength and rigidity.

2. Description of the Related Art Conventionally, wheel bearing devices that support wheels of automobiles and the like support a hub wheel for mounting a wheel rotatably via a rolling bearing, 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. 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. 6), and the side closer to the center is referred to as the inner side (right side in FIG. 6).

In wheel bearing devices composed of such double-row rolling bearings, the left and right rows of bearings have the same specifications, so that they have sufficient rigidity when stationary, but optimal rigidity is always obtained when the vehicle turns. Absent. That is, the position of the vehicle weight when stationary is determined so that it acts on the approximate center of the double row rolling bearing, but when turning, the opposite side of the turning direction (when turning right, the vehicle Larger radial load or axial load is applied to the left axle. Therefore, at the time of turning, it is effective to increase the rigidity of the outer bearing row rather than the inner bearing row. Then, what is shown in FIG. 6 is known as a bearing device for wheels which achieved high rigidity without enlarging an apparatus.

This wheel bearing device 50 has a vehicle body mounting flange 51c integrally attached to a knuckle (not shown) on the outer periphery, and an outer side in which double row outer

rolling surfaces

51a and 51b are formed on the inner periphery. A member 51 and a wheel mounting flange 53 for mounting a wheel (not shown) at one end are integrally formed, and one inner rolling surface 52a facing the double row outer

rolling surfaces

51a and 51b on the outer periphery. The hub wheel 52 having a small-diameter step portion 52b extending in the axial direction from the inner rolling surface 52a and the small-diameter step portion 52b of the hub wheel 52 are externally fitted to the double-row outer

rolling surfaces

51a and 51b. An inner member 55 composed of an inner ring 54 formed with the other inner rolling surface 54a facing each other, double rows of

balls

56, 57 accommodated between both rolling surfaces, and these double rows of

balls

56, 57 Retainer 58 that can roll freely It is composed of a double row angular contact ball bearing with a 59.

The inner ring 54 is fixed in the axial direction by a caulking portion 52c formed by plastically deforming the small-diameter step portion 52b of the hub wheel 52 radially outward.

Seals

60 and 61 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 from the outside into the bearing. And dust are prevented from entering.

Here, the pitch circle diameter D1 of the outer side ball 56 is set to be larger than the pitch circle diameter D2 of the inner side ball 57. Along with this, the inner rolling surface 52a of the hub wheel 52 is expanded in diameter than the inner rolling surface 54a of the inner ring 54, and the outer rolling surface 51a on the outer side of the outer member 51 is also rolled on the inner side. The diameter is larger than that of the surface 51b. The outer side balls 56 are accommodated more than the inner side balls 57. In this way, by setting the pitch circle diameters D1 and D2 to D1> D2, the rigidity is improved not only when the vehicle is stationary but also when turning, and the life of the wheel bearing device 50 can be extended. (For example, refer to Patent Document 1).

JP 2008-292001 A

In such a wheel bearing device 50, the outer member 51 is formed by forging, but the outer portion of the vehicle body mounting flange 51c is generally reduced in diameter from the die-cutting surface toward the outer side. It is. In this case, there is a certain limitation to increase the pitch circle diameter D1 of the outer 56 rows of balls in order to increase bearing rigidity and extend the life.

The present invention has been made in view of such circumstances, focusing on the position of the forging die in the outer member, and ensuring the desired strength and rigidity while reducing the weight and size of the wheel. It aims at providing a bearing device.

In order to achieve such an object, the invention according to claim 1 of the present invention includes an outer member in which a double row outer rolling surface is integrally formed on the inner periphery, and a wheel attachment for attaching a wheel to one end. A hub ring having a flange integrally formed with a small-diameter step portion extending in the axial direction on the outer periphery, and an inward rotation that is press-fitted into the small-diameter step portion of the hub ring and faces the outer surface of the double row on the outer periphery. An inner member composed of at least one inner ring formed with a running surface, and a double row rolling element accommodated in a freely rolling manner between the inner member and the outer member. In the wheel bearing device in which the pitch circle diameter of the outer side rolling element among the double row rolling elements is set larger than the pitch circle diameter of the inner side rolling element, the outer member has an inner side end portion. A plurality of mounting parts that protrude radially outward from the outer peripheral surface of the In addition, a screw hole for fastening the knuckle to the knuckle via a fixing bolt is formed in the mounting portion, and a die splitting position of the forging die of the outer member is an outer periphery between the outer rolling surfaces of the double row. The outer peripheral surface of the outer member is formed so as to have a gradually smaller diameter toward the end portion with the mold dividing position as a base point.

As described above, the wheel bearing device of the second or third generation structure in which the pitch circle diameter of the outer side rolling element of the double row rolling elements is set larger than the pitch circle diameter of the inner side rolling element. The outer member is formed with a plurality of mounting portions extending radially outward from the outer peripheral surface of the inner side end portion and extending in the axial direction. The mounting portion is fastened to the knuckle via a fixing bolt. A screw hole is formed, and the die split position of the forging die of the outer member is set on the outer peripheral surface between the double row outer rolling surfaces, and the outer peripheral surface of the outer member is based on the die split position. Since the diameter is gradually reduced toward the end, it is possible to provide a wheel bearing device that is lightweight and compact while ensuring the desired strength and rigidity by removing surplus as much as possible. it can.

Preferably, as in the invention according to claim 2, the outer member is connected to the inner side through a stepped portion extending in an axially inclined manner from the outer rolling surface of the double row outer rolling surfaces. Side outer rolling surfaces are integrally formed, and cylindrical shoulders are respectively formed on the double row outer rolling surfaces, and these shoulders are formed to a predetermined groove depth by turning, and at least If the stepped part between both shoulders is left forged without turning, the groove depth of the outer rolling surface is strictly regulated, and it can be prevented that edge loading occurs due to shoulder riding, Material loss can be reduced by reducing the number of parts deleted by turning as much as possible.

According to a third aspect of the present invention, a pilot portion of the knuckle is formed on the outer peripheral surface of the inner side end portion of the outer member, the attachment portion is formed on the outer peripheral surface, and the inner If the outer peripheral surface of the side is composed of a projecting surface that forms a tapered ridge line having a predetermined inclination angle that constitutes the outer peripheral surface of the mounting portion, and a concave surface that smoothly connects these projecting surfaces, It is possible to form a substantially uniform thickness with respect to the step portion, and to secure a desired strength and rigidity and to reduce the weight.

According to a fourth aspect of the present invention, the parting position is set in the vicinity of the outer rolling surface on the outer side, a shoulder is formed on the outer side of the parting position, and the inner If the maximum diameter of the outer peripheral surface of the outer side is set larger than the maximum diameter of the outer peripheral surface of the outer side, a wall thickness that can secure the strength and rigidity of the outer member can be obtained, and the outer side outer rotation surface can be secured. The minimum thickness of the running surface can be secured.

According to a fifth aspect of the present invention, the mold dividing position is set in the vicinity of the outer rolling surface on the inner side, a shoulder is formed on the inner side of the mold dividing position, and the inner If the maximum diameter of the outer peripheral surface on the side is set to be smaller than the maximum diameter of the outer peripheral surface on the outer side, a thickness that can ensure the strength and rigidity of the outer member can be obtained, and the surplus thickness of the mounting portion can be reduced. It can be reduced effectively, and the weight of the outer member can be reduced.

According to a sixth aspect of the present invention, the mold dividing position is set at a substantially central position in the axial direction between the outer rolling surfaces of the double row, and the maximum diameter of the outer peripheral surface on the inner side and the outer If the maximum diameter of the outer peripheral surface on the side is set to be the same, a thickness that can ensure the strength and rigidity of the outer member can be obtained, and the minimum thickness of the outer rolling surface on the outer side can be ensured. The surplus of can be reduced.

The wheel bearing device according to the present invention integrally has an outer member integrally formed with a double row outer rolling surface on the inner periphery, and a wheel mounting flange for mounting the wheel on one end, and on the outer periphery. A hub wheel having a small-diameter step portion extending in the axial direction, and at least one inner rolling surface that is press-fitted into the small-diameter step portion of the hub wheel and that faces the outer rolling surface of the double row on the outer periphery. An inner member formed of an inner ring, and a double row rolling element that is rotatably accommodated between both rolling surfaces of the inner member and the outer member, and the outer side of the double row rolling element. In the wheel bearing device in which the pitch circle diameter of the rolling element is set to be larger than the pitch circle diameter of the inner rolling element, the outer member is radially outward from the outer peripheral surface of the inner side end portion. A plurality of mounting portions that protrude and extend in the axial direction are formed. A screw hole is formed for fastening to the outer member via a fixing bolt, and the die splitting position of the forging die of the outer member is set on the outer peripheral surface between the outer rolling surfaces of the double row, Since the outer peripheral surface of the side member is formed with a gradually decreasing diameter toward the end with the above-mentioned dividing position as a base point, it is lightweight while ensuring the desired strength and rigidity by removing as much as possible. It is possible to provide a wheel bearing device that is compact.

It is a longitudinal section showing a 1st embodiment of a bearing device for wheels concerning the present invention. It is a side view of the wheel bearing apparatus of FIG. FIG. 3 is a longitudinal sectional view taken along line II-0-II showing an outer member alone in FIG. 2; 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 3rd 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 having a double row outer rolling surface integrally formed on the inner periphery and a wheel mounting flange for mounting a wheel on one end are integrally formed, and one of the outer rolling surfaces of the double row is formed on the outer periphery. A hub ring having a small-diameter step portion formed through an inner rolling surface opposite to the inner rolling surface and a stepped portion extending in an axial direction from the inner rolling surface, and the outer periphery is press-fitted into the small-diameter step portion of the hub ring. An inner member formed of an inner ring formed with an inner rolling surface facing the other of the outer rolling surfaces of the double row, and freely rollable between both rolling surfaces of the inner member and the outer member. A double-row rolling element housed therein, wherein a pitch circle diameter of an outer-side rolling element among the double-row rolling elements is set larger than a pitch circle diameter of an inner-side rolling element. In the apparatus, there is no vehicle body mounting flange for attaching the outer member to the knuckle on the outer periphery. A cylindrical outer peripheral surface serving as a pilot portion of the knuckle is formed at an inner side end portion of the outer member, and a plurality of attachment portions projecting radially outward from the outer peripheral surface and extending in the axial direction are formed. A screw hole for fastening the knuckle to the knuckle via a fixing bolt is formed in the mounting portion, and the split position of the forging die of the outer member is the center in the axial direction between the outer rolling surfaces of the double row A taper having a predetermined inclination angle that is set on the outer rolling surface side on the outer side and the outer peripheral surface on the inner side of the outer member has a small diameter from the split position toward the outer side through the shoulder. The outer peripheral surface of the inner side is formed of a projecting surface that forms a tapered ridge line having a predetermined inclination angle that becomes the outer peripheral surface of the mounting portion, and a concave surface that smoothly connects these projecting surfaces. ing.

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 a side view of the wheel bearing device of FIG. 1, and FIG. 3 is a single outer member of FIG. FIG. 2 is a longitudinal sectional view taken along line II-0-II. 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 for a driven wheel referred to as a third generation, and is a double row rolling element housed in a freely rollable manner between the inner member 1, the outer member 2, and both

members

1,2. (Balls) 3 and 3. 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 has one (outer side) inner rolling surface 4a on the outer periphery and the inner rolling surface. A small-diameter step portion 4b is formed via a step portion 7 that extends from the surface 4a while being inclined in the axial direction. 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) inner raceway surface 5a on the outer periphery and is press-fitted into the small-diameter stepped portion 4b of the hub wheel 4 to form a back-to-back type double row angular contact ball bearing. The inner ring 5 is fixed in the axial direction by a caulking portion 8 formed by plastic deformation of the end portion of 4b. The inner ring 5 and the rolling element 3 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 portion by quenching.

The hub wheel 4 is formed of medium carbon steel containing 0.40 to 0.80 wt% of carbon such as S53C, and the inner raceway surface 4a and the inner side base portion 6b of the wheel mounting flange 6 to the small diameter step portion 4b. Thus, the surface hardness is set to a range of 58 to 64 HRC by induction hardening. The caulking portion 8 is kept in the 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 step portion 4b serving as the fitting portion of the inner ring 5 is improved, and the minute There is no occurrence of cracks and the like, and the plastic working of the caulking portion 8 can be performed smoothly.

Here, the hub wheel 4 is formed by forging from a bar material as a raw material, and includes a base portion 6b that becomes a land portion of the seal 12 on the outer side, an inner rolling surface 4a, a shoulder portion 7a, and a small-diameter step portion 4b. Are formed in a predetermined dimension by turning, and the stepped portion 7 is formed by a tapered surface having a predetermined inclination angle. That is, the stepped portion 7 is left as a forged surface without being turned. As a result, the groove depth of the inner rolling surface 4a is strictly regulated, and it is possible to prevent the occurrence of an edge load due to shoulder climbing, and to reduce material loss by reducing the number of parts to be deleted by turning as much as possible. Therefore, cost reduction can be achieved.

The hub wheel 4 is hardened by induction hardening after turning. Preferably, the stepped portion remains as a forged skin if the stepped portion 7 is removed by shot blasting before grinding. The scale adhering to the surface of 7 is removed, and burrs at each corner are also removed at the same time and rounded smoothly, ensuring abnormal noise, abnormal vibration, and rotation failure due to scale dropout. Can prevent and improve product quality. Further, a compressive residual stress is formed on the surface of the stepped portion 7, and the strength and durability can be improved against a moment load or the like applied to the hub wheel 4.

The outer member 2 does not have a vehicle body attachment flange to be attached to a knuckle (not shown) on the outer periphery, has an attachment surface 21 to be described later, and an outer member facing the inner rolling surface 4a of the hub wheel 4 on the inner periphery. The inner side outer rolling surface 2b and the inner side outer side rolling surface 2b facing the inner side rolling surface 5a of the inner ring 5 through the step portion 11 extending incline in the axial direction from the outer side rolling surface 2a are integrated. Is formed. Double-

row rolling elements

3 and 3 are accommodated between these rolling surfaces and are held by the

cages

9 and 10 so as to roll freely.

This outer member 2 is formed of medium carbon steel containing 0.40 to 0.80 wt% of carbon such as S53C, and the double row outer rolling surfaces 2a and 2b have a surface hardness in the range of 58 to 64HRC by induction hardening. Has been cured. A seal 12 and a cover (not shown) 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 to the outside is performed. This prevents rainwater and dust from entering the bearing from the outside. In addition, although the wheel bearing apparatus comprised by the double row angular contact ball bearing which used the ball for the rolling element 3 was illustrated here, it is not restricted to this, The double row tapered roller bearing which used the tapered roller for the rolling element 3 It may consist of.

In this embodiment, the pitch circle diameter PCDo of the outer side rolling element 3 is set larger than the pitch circle diameter PCDi of the inner side rolling element 3. The outer diameter do of the outer side rolling element 3 of the double

row rolling elements

3 and 3 is set smaller than the outer diameter di of the inner side rolling element 3 (do <di), and this pitch circle diameter PCDo. Due to the difference in PCDi, the number Zo of the outer side rolling elements 3 is set to be larger than the number Zi of the inner side rolling elements 3 (Zo> Zi).

The outer shape of the hub wheel 4 continues from the groove bottom portion of the inner rolling surface 4a to the step portion 7 and the small diameter step portion 4b through the shoulder portion 7a against which the inner ring 5 is abutted. A mortar-shaped recess 14 is formed at the outer end of the hub wheel 4. The depth of the recess 14 is the depth from the outer end surface to the vicinity of the shoulder 7a beyond the groove bottom 13 position of the inner rolling surface 4a, and the outer end of the hub wheel 4 is substantially uniform. It is thick. Further, the inner rolling surface 4 a of the hub wheel 4 is formed to have a larger diameter than the inner rolling surface 5 a of the inner ring 5 in accordance with the difference between the pitch circle diameters PCDo and PCDi.

On the other hand, in the outer member 2, as shown in FIG. 3, the outer side outer rolling surface 2a is formed with a larger diameter than the inner side outer rolling surface 2b due to the difference in pitch circle diameters PCDo and PCDi. Then, the outer side rolling surface 2a of the outer side continues from the shoulder portion 15 on the large diameter side via the step portion 11 to the shoulder portion 16 on the small diameter side and reaches the outer side rolling surface 2b on the inner side.

Here, the outer member 2 is formed by forging from a bar material as a raw material, and includes an outer peripheral surface 24 on the inner side on which both ends and a knuckle (not shown) are fitted, a seal 12 and a cover. The fitting surfaces 19 and 20 to be mounted, the double-row outer rolling surfaces 2a and 2b, the large-diameter side shoulder 15 and the small-diameter side shoulder 16 of the double-row outer rolling surfaces 2a and 2b are provided. Forging is performed with a predetermined turning allowance remaining.

The shoulder portion 15 on the large diameter side and the shoulder portion 16 on the small diameter side are formed to a predetermined groove depth by turning, and the step portion 11 between the

shoulder portions

15 and 16 is a tapered surface having a predetermined inclination angle. Is formed. In other words, the stepped portion 11 is left as a forged surface without being turned. As a result, the groove depth of the outer rolling surfaces 2a and 2b is strictly regulated, and it is possible to prevent the occurrence of edge loading due to shoulder climbing, and to reduce the portion to be deleted by turning as much as possible. The cost can be reduced.

The outer member 2 is hardened by induction hardening after turning, but the stepped portion 11 between the double row

outer rolling surfaces

2a, 2b is not hardened, and the

outer rolling surfaces

2a, 2b are not hardened. The curing process is discontinuous. Thereby, while thinning between rows can be achieved, it is possible to easily process the screw holes 18 of the mounting surface 21.

Further, preferably, if the scale of the step portion 11 is removed by shot blasting before the grinding process, the scale attached to the surface of the step portion 11 is removed, and burrs and the like at the respective corner portions are simultaneously removed. It is removed and smoothly rounded, and it is possible to reliably prevent abnormal noise, abnormal vibration, and rotation failure during operation caused by dropout of the scale, thereby improving product quality. Further, a compressive residual stress is formed on the surface of the step portion 11, and the strength and durability can be improved.

In such a wheel bearing device, the pitch circle diameter PCDo of the outer side rolling element 3 is set larger than the pitch circle diameter PCDi of the inner side rolling element 3 (PCDo> PCDi), and the outer side rolling element is set. 3 is set to be smaller than the outer diameter di of the inner side rolling element 3 (do <di), and accordingly, the number Zo of the outer side rolling elements 3 is larger than the number Zi on the inner side ( Since Zo> Zi) is set, the bearing space can be effectively utilized to increase the bearing rigidity of the outer side portion compared to the inner side, and the life of the bearing can be extended. Furthermore, since the recess 14 is formed along the outer shape at the outer end of the hub wheel 4 and the outer side of the hub wheel 4 is set to a uniform thickness, the device is lighter, more compact and more rigid. It can solve the conflicting issues.

Here, in the present embodiment, the die splitting position A of the forging die of the outer member 2 is the outer periphery on the outer rolling surface 2a side on the outer side from the axial center between the double row

outer rolling surfaces

2a, 2b. With the difference in pitch circle diameters PCDo and PCDi, the outer peripheral surface of the outer member 2 starts from the parting position A and the outer peripheral surface 22 on the outer side extends from the parting position A to the shoulder 23. Is formed on a tapered surface having a predetermined inclination angle θ1 having a small diameter toward the outer side.

On the other hand, a plurality (four in this case) of mounting portions 17 are formed at equal intervals in the outer circumferential surface 24 of the inner side end portion which is a pilot portion of a knuckle (not shown). A mounting surface 21 is formed in parallel with the end surface. Then, the outer peripheral surface 25 on the inner side is formed so as to gradually decrease in diameter from the parting position A toward the inner side with the parting position A as a base point. Specifically, the outer peripheral surface 25 on the inner side smoothly connects the protruding surface 25a that forms a tapered ridge line having a predetermined inclination angle θ2 that constitutes the outer peripheral surface of the mounting portion 17, and the inner diameter of the protruding surface 25a. It is comprised with the recessed surface 25b which forms the substantially uniform thickness with respect to the level | step difference part 11 of the side.

As shown in FIG. 2, the mounting portion 17 is formed to protrude radially outward from the outer peripheral surface 24 of the inner side end portion, and the mounting surface 21 has a screw hole 18 extending in the axial direction. The knuckle is fitted to the outer peripheral surface 24 at the inner side end and is joined to the mounting surface 21, and the outer member 2 is fastened to the knuckle via a fixing bolt (not shown). In addition, the minimum diameter Di of the attachment part 17 is set as the protrusion amount of the attachment part 17 according to the size of the fixing bolt (not shown) fastened to the knuckle, that is, the size of the screw hole 18.

The inclination angles θ1 and θ2 between the outer peripheral surface 22 on the outer side and the outer peripheral surface 25a on the inner side are set to a range of 5 to 10 °, which is larger than the draft (1 to 5 °) during normal forging. ing. As a result, these inclination angles θ1 and θ2 can be applied as draft angles during forging, the weight of the outer member 2 can be reduced, the forging weight of the material can be reduced, and the cost can be reduced. Can be planned.

In the present invention, the parting position A is set so that a thickness capable of securing the strength and rigidity of the outer member 2 is obtained, and the outer thickness is secured so that a minimum thickness of the outer rolling surface 2a on the outer side can be secured. The minimum diameter Do of the outer peripheral surface 22 on the side is set. In this embodiment, since the parting position A is set in the vicinity of the outer-side outer rolling surface 2a, the maximum diameter Dimax of the inner-side outer peripheral surface 25a is larger than the maximum diameter Domax of the outer-side outer peripheral surface 22. The diameter is large (Dimax> Domax), and a shoulder 23 is formed on the outer side of the parting position A.

As described above, in this embodiment, the outer peripheral surface of the outer member 2 is not formed with a vehicle body mounting flange that is fastened to a knuckle as in the related art. A forging mold split position A is set between the rolling

surfaces

2a and 2b, and the outer peripheral surface 22 is composed of an outer peripheral surface 22 on the outer side and an outer peripheral surface 25 on the inner side. Since the

diameters

22 and 25 are gradually reduced toward the end portions, the wheel bearing device is made lighter and more compact while ensuring the desired strength and rigidity by removing as much as possible. Can be provided.

FIG. 4 is a longitudinal sectional view showing a second embodiment of the wheel bearing device according to the present invention. The second embodiment is basically different from the first embodiment (FIG. 1) described above, except that the configuration of the outer member is basically the same. Parts are denoted by the same reference numerals and detailed description thereof is omitted.

This wheel bearing device is called the third generation for driven wheels, and is a double

row rolling element

3, 3 accommodated in a freely rollable manner between the inner member 1, the outer member 26, and both

members

1, 26. And.

The outer member 26 does not have a vehicle body mounting flange to be attached to a knuckle (not shown) on the outer periphery, and has an outer outer rolling surface 2a facing the inner rolling surface 4a of the hub wheel 4 on the inner periphery, An inner-side outer rolling surface 2b facing the inner rolling surface 5a of the inner ring 5 is integrally formed through a step portion 11 that extends from the outer rolling surface 2a so as to be inclined in the axial direction. This outer member 26 is made of medium carbon steel containing 0.40 to 0.80 wt% of carbon such as S53C, and the double row outer rolling surfaces 2a and 2b have a surface hardness in the range of 58 to 64HRC by induction hardening. Has been cured.

Here, the outer member 26 is formed by a forging process from a bar material as a raw material, and includes an outer peripheral surface 24 on the inner side to which a knuckle (not shown) is fitted, a seal 12 and a cover. The fitting surfaces 19 and 20 to be mounted, the double-row outer rolling surfaces 2a and 2b, the large-diameter side shoulder 15 and the small-diameter side shoulder 16 of the double-row outer rolling surfaces 2a and 2b are provided. Forging is performed with a predetermined turning allowance remaining.

Here, in this embodiment, the die splitting position B of the forging die of the outer member 26 is the outer periphery on the outer rolling surface 2b side on the inner side from the axial center between the double row

outer rolling surfaces

2a, 2b. In accordance with the difference in pitch circle diameters PCDo and PCDi, the outer peripheral surface 27 on the outer side of the outer member 26 has a predetermined inclination angle that becomes smaller in diameter toward the outer side with the mold dividing position B as a base point. It is formed on a tapered surface made of θ1.

On the other hand, on the outer peripheral surface 24 of the inner side end portion, a plurality of (four in this case) mounting portions 17 are formed in a circumferentially equidistant manner, and the mounting surface is parallel to the end surface of the outer member 26. 21 is formed. Then, the outer peripheral surface 28 on the inner side is formed with a gradually decreasing diameter from the mold dividing position B toward the inner side through the shoulder 29 with the mold dividing position B as a base point. Specifically, the outer peripheral surface 28 on the inner side smoothly connects the protruding surface 28a having a tapered ridge line having a predetermined inclination angle θ2 that constitutes the outer peripheral surface of the mounting portion 17, and the inner diameter of the protruding surface 28a. It is comprised with the recessed surface 28b which forms the substantially uniform thickness with respect to the level | step difference part 11 of the side.

In this embodiment, since the parting position B is set in the vicinity of the inner side outer rolling surface 2b, the maximum diameter Dimax of the inner side outer peripheral surface 28a is larger than the maximum diameter Domax of the outer side outer peripheral surface 27. A small diameter (Dimax <Domax) is established, and a shoulder 29 is formed on the inner side of the parting position B. Thereby, the thickness which can ensure the intensity | strength and rigidity of the outer member 26 is obtained, the surplus thickness of the attaching part 17 can be reduced effectively, and the weight reduction of the outer member 26 can be achieved.

As described above, in the present embodiment, a vehicle body mounting flange that is fastened to a knuckle as in the related art is not formed on the outer peripheral surface of the outer member 26, and the double-row outer side of the outer peripheral surface of the outer member 26 is formed. A die splitting position B of the forging die is set between the rolling

surfaces

2a and 2b, and is composed of an outer peripheral surface 27 on the outer side and an outer peripheral surface 28 on the inner side with the die splitting position B as a base point. 27 and 28 are formed with progressively smaller diameters toward the ends, respectively, so that, as in the above-described embodiment, the excess thickness is removed as much as possible to ensure the desired strength and rigidity, while reducing the weight and size. Can be achieved.

FIG. 5 is a longitudinal sectional view showing a third embodiment of the wheel bearing device according to the present invention. Note that this third embodiment is basically different from the second embodiment (FIG. 4) described above except that the configuration of the outer member is the same. Parts are denoted by the same reference numerals and detailed description thereof is omitted.

This wheel bearing device is referred to as a third generation for driven wheels, and includes an inner member 1 and an outer member 30, and double

row rolling elements

3, 3 accommodated between both members 1 and 30 in a freely rolling manner. And.

The outer member 30 does not have a vehicle body mounting flange to be attached to a knuckle (not shown) on the outer periphery, and has an outer outer rolling surface 2a facing the inner rolling surface 4a of the hub wheel 4 on the inner periphery, An inner-side outer rolling surface 2b facing the inner rolling surface 5a of the inner ring 5 is integrally formed through a step portion 11 that extends from the outer rolling surface 2a so as to be inclined in the axial direction. This outer member 30 is made of medium carbon steel containing 0.40 to 0.80 wt% of carbon such as S53C, and the double row outer rolling surfaces 2a and 2b have a surface hardness in the range of 58 to 64HRC by induction hardening. Has been cured.

Here, the outer member 30 is formed by a forging process from a bar material as a raw material, and includes an outer peripheral surface 24 on the inner side to which a knuckle (not shown) is fitted, a seal 12 and a cover. The fitting surfaces 19 and 20 to be mounted, the double-row outer rolling surfaces 2a and 2b, the large-diameter side shoulder 15 and the small-diameter side shoulder 16 of the double-row outer rolling surfaces 2a and 2b are provided. Forging is performed with a predetermined turning allowance remaining.

Here, in this embodiment, the die splitting position C of the forging die of the outer member 30 is set to the outer peripheral surface in the approximate center in the axial direction between the double row

outer rolling surfaces

2a, 2b, and the pitch circle diameter PCDo. With the difference in PCDi, the outer peripheral surface 31 on the outer side of the outer member 30 is formed into a tapered surface having a predetermined inclination angle θ1 that has a smaller diameter toward the outer side with the mold dividing position C as a base point. Yes.

On the other hand, on the outer peripheral surface 32 of the inner side end portion, a plurality of (four in this case) mounting portions 17 are formed in the circumferential direction, and the mounting surface is parallel to the end surface of the outer member 30. 21 is formed. Then, the outer peripheral surface 32 on the inner side is formed with a gradually decreasing diameter from the parting position C toward the inner side with the parting position C as a base point. Specifically, the outer peripheral surface 32 on the inner side smoothly connects the protruding surface 32a having a tapered ridge line having a predetermined inclination angle θ2 constituting the outer peripheral surface of the mounting portion 17, and the inner diameter of the protruding surface 32a. It is comprised with the recessed surface 32b which forms the substantially uniform thickness with respect to the level | step difference part 11 of the side.

In this embodiment, since the parting position C is set to the outer peripheral surface at the substantially center in the axial direction between the double row

outer rolling surfaces

2a, 2b, the maximum diameter Dimax of the outer peripheral surface 32a on the inner side is set to the outer side. It becomes the same as the maximum diameter Domax of the outer peripheral surface 31 (Dimax = Domax).

As described above, in the present embodiment, a vehicle body mounting flange that is fastened to a knuckle as in the related art is not formed on the outer peripheral surface of the outer member 30. A forging die split position C is set on the outer peripheral surface in the substantially axial center between the rolling

surfaces

2a and 2b, and the outer peripheral surface 31 and the outer peripheral surface 32 on the inner side are set based on the split position C. Since the outer peripheral surfaces 31 and 32 are gradually formed with small diameters toward the end portions, as in the above-described embodiment, the surplus wall is removed as much as possible to obtain the desired strength and rigidity. While ensuring, it can be light and compact.

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 second or third generation structure for a driven wheel.

DESCRIPTION OF SYMBOLS 1 Inner member 2, 26, 30 Outer member 2a, 2b Outer rolling surface 3 Rolling body 4 Hub wheel 4a, 5a Inner rolling surface 4b Small diameter step part 5 Inner ring 6 Wheel mounting flange 6a Hub bolt 6b Inner wheel mounting flange Side base 7, 11 Stepped portion 7 a, 23, 29 Shoulder 8 Clamping portion 9, 10 Cage 12 Outer side seal 13 Groove bottom 14 on inner rolling surface Recess 15 Large diameter side shoulder 16 Small diameter side Shoulder portion 17 mounting portion 18 screw hole 19, 20 fitting surface 21 mounting surface 22, 27, 31 outer peripheral surface 24 of outer member outer peripheral surface 25, 28, 32 outer member inner side end Outer peripheral surfaces 25a, 28a, 32a on the inner side of the side members Projecting surfaces 25b, 28b, 32b Recessed surfaces 50 Wheel bearing devices 51 Outer members 51a Outer rolling surfaces 51b Outer rolling surfaces 51b Inner outer rolling surfaces 51c Hula Ring 52 Hub wheel 52a, 54a Inner rolling surface 52b Small diameter step portion 52c Clamping portion 53 Wheel mounting flange 54 Inner ring 55 Inner member 56, 57 Ball 58, 59 Cage 60, 61 Seal A, B, C Outer member Split position AA of outer member Outer outer peripheral surface BB Outer member inner outer peripheral surface di Inner side rolling element outer diameter do Outer side rolling element outer diameter D1 Outer side outer peripheral surface D1 Ball pitch circle diameter D2 Inner side pitch circle diameter Di Minimum diameter of outer member mounting portion Do Outer outer peripheral surface minimum diameter Dimax Inner outer peripheral surface maximum diameter Domax Outer outer peripheral surface maximum Diameter PCDi Pitch circle diameter of inner side rolling element PCDo Pitch circle diameter of outer side rolling element Zi Number of inner side rolling element Zo Number of outer side rolling element θ1 Inclination angle of outer peripheral surface on outer side θ2 Inclination angle of outer peripheral surface on inner side

Claims

An outer member in which a double row outer rolling surface is integrally formed on the inner periphery;
A hub wheel integrally having a wheel mounting flange for mounting a wheel at one end, a small diameter step portion extending in the axial direction on the outer periphery, and a small diameter step portion of the hub wheel are press-fitted, and the double row is disposed on the outer periphery. An inner member composed of at least one inner ring formed with an inner rolling surface facing the outer rolling surface of
A double row rolling element housed in a freely rolling manner between the rolling surfaces of the inner member and the outer member;
In the wheel bearing device in which the pitch circle diameter of the outer side rolling elements of the double row rolling elements is set larger than the pitch circle diameter of the inner side rolling elements,
The outer member is formed with a plurality of mounting portions extending radially outward from the outer peripheral surface of the inner side end portion and extending in the axial direction. The mounting portion is fastened to the knuckle via a fixing bolt. A screw hole is formed, and the die splitting position of the forging die of the outer member is set on the outer peripheral surface between the outer rolling surfaces of the double row, and the outer peripheral surface of the outer member is set to the die splitting position. The wheel bearing device is characterized by being formed with a gradually decreasing diameter from the base point toward the end.
The outer member is formed integrally with an outer rolling surface on the inner side through a stepped portion extending in an axial direction from the outer rolling surface of the double row outer rolling surfaces. Cylindrical shoulders are formed on the outer rolling surfaces of the rows, and the shoulders are formed to a predetermined groove depth by turning, and at least the stepped portion between the shoulders is forged without turning. The wheel bearing device according to claim 1, wherein the wheel bearing device is left intact.
A pilot portion of the knuckle is formed on the outer peripheral surface of the inner side end portion of the outer member, the mounting portion is formed on the outer peripheral surface, and the outer peripheral surface of the inner side is the outer peripheral surface of the mounting portion. The wheel bearing device according to claim 1 or 2, comprising a projecting surface that forms a tapered ridge line having a predetermined inclination angle and a recessed surface that smoothly connects the projecting surfaces.
The parting position is set near the outer rolling surface on the outer side, a shoulder is formed on the outer side of the parting position, and the maximum diameter of the outer peripheral surface on the inner side is the outer periphery on the outer side The wheel bearing device according to claim 1, wherein the wheel bearing device is set to have a larger diameter than a maximum diameter of the surface.
The parting position is set in the vicinity of the outer rolling surface on the inner side, a shoulder is formed on the inner side of the parting position, and the maximum diameter of the outer peripheral surface on the inner side is the outer periphery on the outer side The wheel bearing device according to claim 1, wherein the wheel bearing device is set to be smaller than the maximum diameter of the surface.
The mold dividing position is set at approximately the center in the axial direction between the outer rolling surfaces of the double row, and the maximum diameter of the outer peripheral surface on the inner side and the maximum diameter of the outer peripheral surface on the outer side are set to be the same. The wheel bearing device according to claim 1.