JP2005212713A - Wheel bearing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase the durability of a bearing device by preventing an excessive tensile load from acting on a round portion between a small diameter step portion of a hub and a step face of the hub in the small diameter step portion formed on an outer circumference of a hub ring such that a member such as an inner ring can be fixed. <P>SOLUTION: In the bearing device 1 for a wheel in which a member such as the inner ring 3 is fixed on the small diameter step portion 8 formed on an outer circumference of the hub 2, the junction of the step face 12 and the small diameter step portion 8 having a reduced outside diameter dimension on the outer circumference of the hub 2 is provided with a groove 31 delimited by a single circular arc having a larger radius than a chamfer face 27 of the member such as the inner ring 3 fitted thereon to preclude contact with the member such as the inner ring. The design can absorb deformation by an excessive tensile load under a large static load to relieve stress concentration under a large static load. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a wheel bearing device for rotatably supporting a vehicle wheel with respect to a vehicle body, and more particularly to a wheel bearing device in which stress is not concentrated on an inner ring fitting step on the outer periphery of a hub shaft.

  The wheels of the automobile are supported on the suspension device by a wheel support bearing device. FIG. 5 shows an example of a wheel support bearing device that has been widely used conventionally. The wheel support bearing device 1 includes a hub 2, an inner ring 3, an outer ring 4, and a plurality of rolling elements 5 and 5. A flange 6 for supporting the wheel is formed at the outer end of the outer peripheral surface of the hub 2. Further, a first inner ring raceway 7 is formed at an intermediate portion of the hub 2, and a small diameter step portion 8 having a smaller outer diameter is formed at the inner end portion. This type of wheel support bearing device is disclosed in a number of publications such as Japanese Patent Application Laid-Open No. 2003-48405.

  In the state where the wheel support bearing device 1 is attached to the vehicle body, the flange 6 to which the wheel is attached is usually located on the outer side in the width direction of the vehicle body, and the opposite side is closer to the center in the width direction of the vehicle body and on the inner side of the vehicle body. Therefore, as shown in the drawings, hereinafter, in each member of the wheel supporting bearing device 1, the flange 6 side is referred to as an outer side, and the opposite side is referred to as an inner side.

  Then, the inner ring 3 is press-fitted into the outer periphery of the small-diameter stepped portion 8, and the inner end member having the double row transfer surfaces 7 and 9 is grooved by abutting the outer end surface of the inner ring 3 with the stepped surface 12 of the hub 2. The In the illustrated bearing device, one of the double-row transfer surfaces of the inner member is directly formed on the outer periphery of the hub 2, and the other 9 is formed on the outer periphery of the inner ring 3.

  A male screw portion 10 is formed at the inner end portion of the hub 2, and the tip end portion of the male screw portion 10 protrudes inward from the inner end surface of the inner ring 3. Then, the inner ring 3 is clamped and fixed to a predetermined position of the hub 2 by sandwiching the inner ring 3 between the nut 11 screwed into the male screw part 10 and the step surface 12 of the small diameter step part 8. Yes. A locking recess 17 is formed on the outer peripheral surface of the distal end portion of the male screw portion 10. Then, after tightening the nut 11 with a predetermined torque, a portion of the nut 11 that is aligned with the recess 17 is caulked inward in the diametrical direction to prevent the nut 11 from loosening.

  A first outer ring raceway 13 that faces the first inner ring raceway 7 and a second outer ring raceway 14 that faces the second inner ring raceway 9 are formed on the inner peripheral surface of the outer ring 4. . A plurality of rolling elements 5 and 5 are provided between the first and second inner ring raceways 7 and 9 and the first and second outer ring raceways 13 and 14, respectively. In the illustrated example, balls are used as the rolling elements 5 and 5. However, in the case of a heavy vehicle hub unit, tapered rollers may be used as these rolling elements.

  Further, in the illustrated example, by providing a seal ring 22 between the outer peripheral surface of the outer end portion of the outer ring 4 and the outer peripheral surface of the hub 2, dust enters the space where the rolling elements 5 and 5 are installed. Or the lubricating oil or the like is prevented from leaking from this space. Further, a lid body 23 that closes the inner end opening of the outer ring 4 is attached to the inner end of the outer ring 4.

  In order to assemble the wheel support bearing device 1 as described above to an automobile, the outer ring 4 is fixed to a suspension device by an outward flange-shaped mounting portion 15 formed on the outer peripheral surface thereof, and the wheel is fixed to the flange 8. . As a result, this wheel is rotatably supported with respect to the suspension device.

  US Pat. No. 5,226,738 describes a wheel support bearing device 1 having a structure as shown in FIG. In the case of the second example of this conventional structure, a caulking portion 16 is formed by bending a portion of the inner end portion of the hub 2 that protrudes inward from the inner end surface of the inner end 3 outward in the diameter direction. The inner ring 3 is sandwiched between the caulking portion 16 and the step surface 12 of the small diameter step portion 8.

  On the other hand, in the case of the second example of the conventional groove structure shown in FIG. 6, it is possible to eliminate troublesome parts manufacturing work and assembly work, but the caulking portion 16 for fixing the inner ring 3 to the hub 2 is fixed. At the time of formation, a force directed outward in the diametrical direction is applied to the inner peripheral surface of the inner ring 3 to which the caulking portion 16 is adjacent, so that the diameter of the inner ring 3 changes although it is slight. And when this amount of change becomes large, there is a risk of excessive preload or preload loss.

  In order to eliminate such inconvenience, Japanese Patent Application Laid-Open No. 9-220904 describes a wheel support bearing device 1 having a structure as shown in FIG. In the case of the third example of the conventional structure, a portion closer to the inner end of the intermediate portion of the small diameter step portion 8 formed at the inner end portion of the hub 2 protrudes inward than the inner ring 3 fitted on the small diameter step portion 8. A spacer 18, which is formed in a circular shape with a rectangular cross section by a metal having sufficient rigidity such as steel, is externally fitted to the part. By forming a circular recess 19 in the inner end surface of the hub 2, a cylindrical portion 20 is formed at the inner end portion of the hub 2. From the inner side surface of the spacer 18 at the inner end portion of the cylindrical portion 20. Further, the caulking portion 16 is formed by caulking and expanding the portion protruding inward in the diametrically outward direction.

In the case of the wheel supporting bearing device 1 as shown in FIG. 7, even if the caulking strength of the caulking portion 16 is sufficiently increased by providing the spacer 18, the inner ring 3 is elastically deformed in the diameter direction. This can be reliably prevented, and the diameter of the inner ring 3 is not changed with the formation of the caulking portion 16.
JP 2003-48405 A US Pat. No. 5,226,738 Japanese Patent Laid-Open No. 9-220904

  Conventionally, the wheel bearing device has been designed mainly by examining the rolling life of a rolling contact surface due to repeated load, fatigue failure, and strength under a static large load. During actual use of the bearing device, a vertical bending moment due to a lateral load acts as the vehicle turns, and the hub repeatedly receives a large bending moment load. It is considered that the repeated load of this large moment load greatly affects the fatigue resistance of the bearing device.

  When examining the strength under the static large load, if a static large load is received, an excessive tensile load acts on the R portion between the small-diameter step portion 8 of the hub 2 and the step surface 12 of the hub 2, There was a problem of having a great influence on the durability of the bearing device.

  That is, in the conventional wheel support bearing device, for example, as shown in FIG. 8A, an enlarged cross section near the step R surface 28 between the small diameter step portion 8 of the hub 2 and the step surface 12 of the hub 2 is shown. The chamfered R surface 27 of the inner ring 3 is a surface having a radius r1 with O1 as the center, whereas the radius r2 of the stepped R surface 28 is at least the same as the radius r1, or O2 with some allowance. A radius smaller than the center radius r1 is formed.

  That is, when the radius r2 of the step R surface 28 is larger than the radius r1 of the chamfered R surface 27 of the inner ring 3, the inner ring 3 is fitted into the small diameter step portion 8 of the hub 2 from the inside as shown in FIG. When mating, first, the chamfered R surface 27 abuts on the step R surface 28, so that the outer end surface 29 of the inner ring cannot abut on the step surface 12. This is because the granting cannot be performed properly.

  For example, as shown in FIG. 8B, when the stepped R surface 28 of the hub 2 has substantially the same radius R1 as the chamfered R surface 27 of the inner ring 3, the grinding relief groove 29 is forged or cut. It may be formed by. Such grinding relief grooves 29 may be of various shapes. In many cases, however, the grinding groove 29 has a surface such as a radius r3 centered on O3. At this time, the radius r3 is at least a chamfered R surface of the inner ring 3. The radius R1 is not larger than the radius r1 of 27, and is set to a radius smaller than the radius r2 of the stepped R surface 28 shown in FIG.

  In this way, the step R surface 28 portion between the small diameter step 8 and the step surface 12 of the hub 2 where the load tends to concentrate is at least the same radius as or smaller than the chamfer R surface 27 of the inner ring. Therefore, an excessive tensile load acts on this portion as described above, which causes a decrease in the durability of the bearing device.

  Therefore, according to the present invention, in the small diameter step portion for fitting the inner ring formed on the outer peripheral surface of the hub wheel in the wheel support bearing device, an excessive tensile load is applied to the R portion between the small diameter step portion of the hub and the step surface of the hub. It is intended to prevent the working and improve the durability of the bearing device.

  The wheel support bearing device of the present invention is similar to the wheel support bearing device of the first example shown in FIG. 5 or the second example of the conventional wheel support shown in FIG. The outer diameter of the flange for supporting the wheel is also larger than the part where the first inner ring raceway is formed at the inner end part, either directly or via a separate inner ring at the intermediate part. A small diameter step portion with a reduced diameter, a hub formed on the outer peripheral surface, a second inner ring raceway on the outer peripheral surface, an outer ring fitted on the small diameter step portion, and an inner peripheral surface on the first inner ring raceway. Between the first outer ring raceway and the outer ring forming the second outer ring raceway facing the second inner ring raceway, and between the first and second inner ring raceways and the first and second outer ring raceways. And a plurality of rolling elements provided respectively. In such a wheel support bearing device, particularly in the wheel support bearing device of the present invention, in order to alleviate the stress concentration generated in the base portion of the small diameter step portion of the hub, the step is provided at the base portion of the small diameter step portion. A groove having a larger radius than a chamfered R surface of a member fitted to the portion and having a single arc not contacting the member is formed.

  According to another wheel support bearing device of the present invention, in the wheel support bearing device, a radially outer end of the groove is radially outer than an end of the chamfered R surface of the member to be fitted. It is located in.

  Furthermore, the other wheel support bearing device of the present invention is the wheel support bearing device, wherein the end portion on the axially inner side of the groove is on the inner side in the axial direction than the end portion of the chamfered R surface of the member to be fitted. It is located in.

  As described above, the wheel support bearing device of the present invention has an inner ring at the connection portion when an excessive tensile load is applied to the small-diameter step portion, step surface and connection portion of the hub under a large static load. Since the relief groove having a radius larger than the radius of the chamfered R surface of the member is formed so as not to hinder the incorporation of the member such as the inner ring, the deformation due to the static excessive load as described above is absorbed. , Stress concentration can be relaxed compared to the conventional one.

  The present invention provides an excessive tensile load on an R portion between a small-diameter step portion of the hub and the step surface of the hub in a small-diameter step portion for fitting a member such as an inner ring formed on the outer peripheral surface of the hub wheel in a wheel support bearing device. In order to improve the durability of the bearing device, the flange for supporting the wheel on the outer end of the outer peripheral surface can be directly connected to the intermediate part directly or via a separate inner ring. The inner ring raceway has a hub having a small diameter step portion whose outer diameter is smaller than the portion where the first inner ring raceway is formed at the inner end portion, and a second inner ring raceway on the outer peripheral surface. And an inner ring that is externally fitted to the small-diameter step portion, a first outer ring raceway that faces the first inner raceway, and a second outer ring raceway that faces the second inner ring raceway are formed on the inner peripheral surface. Between the outer ring, the first and second inner ring raceways and the first and second outer ring raceways, A bearing device for supporting a wheel including a plurality of rolling elements, wherein the base has a larger radius than a chamfered R surface of a member fitted to the step portion at the base of the small-diameter step portion of the hub. This is realized by forming a groove made of a single arc that does not come into contact.

  FIG. 1 shows a first example of an embodiment of the present invention. The feature of this example relates to the R portion between the small-diameter step portion 8 and the step surface 12 formed at the inner end portion of the hub 2, and the structure and operation of the other portions will be described with reference to FIG. 1 is the same as the first example of the conventional structure shown in FIG. 6, the second example of the conventional structure shown in FIG. 6, or the third example shown in FIG. The description will be omitted or simplified, and the description will focus on the features of the present invention.

  In FIG. 1 (a), the inner ring 3 is externally fitted from the inside of the small diameter step portion 8 to the small diameter step portion 8 formed at the inner end portion of the hub 2, and a cylinder formed inward from the inner ring 3. The caulking portion 16 is formed by caulking and expanding the portion 20 outward in the diametrical direction, and the caulking portion 16 suppresses the outer end surface of the caulking portion toward the inner end surface 21 of the inner ring 3. Although it is sandwiched between the stepped surface 12 and connected and fixed to the hub 2, it is the same as the conventional example, but particularly in the present invention, an enlarged view of the main part is shown in FIG. In addition, a groove 31 having a diameter larger than that of the chamfered R surface 27 of the inner ring 3 is formed at a connecting corner portion between the small diameter step portion 8 and the step surface 12.

  Further, as shown in FIG. 2A in which the main portion is enlarged, the chamfered R surface 27 of the inner ring 3 is a curved surface having a radius r1 centered on O1, and the curved surface range is an angle α1. When extending from the position A1 on the outer end surface 29 of the inner ring 3 to the position B1 on the radially inner surface 30 of the inner ring 3, the groove inner surface 32 of the groove 31 in the embodiment of FIG. It is formed of a curved surface having a radius r2 larger than the radius r1 with O2 being the same position as the center of the surface 27 as the center. Accordingly, the groove inner surface 32 of the groove 31 extends by an angle α2 from the position A2 on the step surface 12 to the position B2 on the small diameter step portion 8, and the inner ring 3 fitted to the small diameter step portion 8 is chamfered within this range. The inner ring 3 is no longer in contact with the surface 27.

  1A, the end A2 on the stepped surface 12 side of the groove inner surface 32 is positioned radially outward from the end A1 on the outer end surface 29 side of the chamfered R surface 27. The end B2 of the groove inner surface 32 on the small diameter step portion 8 side is located on the outer side in the axial direction from the end B1 of the chamfered R surface 27 on the radial inner surface 30 side.

  In the case of the wheel support bearing device 1 of the present embodiment configured as described above, the groove inner surface 32 of the groove 31 formed at the connection portion between the small diameter step portion 8 formed at the inner end portion of the hub 2 and the step surface 12 is provided. The radial end A2 of the groove inner surface 32 is positioned at least radially outward from the radial end A1 of the chamfered R surface 27 of the inner ring 3 with a larger radius than the chamfered R surface 27 of the inner ring 3. The axial end B2 of the groove inner surface 32 is formed so as to be positioned at least inward in the axial direction from the axially outer end B1 of the chamfered R surface 27 of the inner ring 3, and when the inner ring 3 is fitted to the small diameter step 8 In FIG. 2, the groove 31 can be formed in various embodiments so that the inner ring 3 does not contact the groove inner surface 32. For example, a simple deformation as shown in FIGS. 2B and 2C can be performed. .

  That is, in the example shown in FIG. 2B, the center position O3 of the groove 31 is arranged on the radially inner side of the surface to be formed with respect to the center position O1 of the chamfered R surface 27 of the inner ring 3, and the radius is set larger. Thus, an example is shown in which the positions of both end portions A2 and B2 of the groove inner surface 32 are the same as those in the above example. In the example shown in FIG. 2 (c), conversely to (b), the center position O4 of the groove 31 is arranged radially outward of the surface to be formed from the center position O1 of the chamfered R surface 27 of the inner ring 3. Then, by setting the radius large, the positions of both end portions A2 and B2 of the groove inner surface 32 are set to the same positions as in the above example, and the inner ring is not in contact with the groove inner surface 32 as described above. . With this setting, the radius of the groove inner surface to be formed can be set in various ways while keeping the position of the end of the groove inner surface 32 the same.

  In each of the above embodiments, various modes have been shown in the case where the end portion of the groove inner surface 32 is set at the same position of A2 and B2. However, in the present invention, various types can be used as long as the above conditions are met. It can be implemented in an embodiment.

  By forming such a groove 31, it is possible to absorb deformation caused by an excessive tensile load under a static large load, and to reduce stress concentration when a static large load is applied. It becomes possible.

  In the above embodiment, an example in which the inner ring raceway 7 is formed directly on the outer periphery of the hub 2 has been shown. However, the present invention can be applied to a wheel support bearing device 1 as shown in FIG. That is, in the embodiment shown in FIG. 3, a small-diameter step portion 8 is immediately formed inside the flange 6 of the hub 2, and the first inner ring 33 and the second inner ring 34 are sequentially fitted to the small-diameter step portion 8, and thereafter In the same manner as in the above embodiment, the cylindrical portion formed inside the hub 2 is caulked outward to form the caulking portion 16, and the outer end surface 35 of the first inner ring 33 is pressed against the step surface 12 of the hub 2. Are firmly fixed to the hub 2 integrally, and in this embodiment, a sphere is used as the rolling element in the above embodiment, but an example using conical rollers 36 and 37 is used. Show.

  Also in the wheel support bearing device 1 as described above, the step is formed at a portion where the step surface 12 of the hub 2 and the small diameter step portion 8 of the hub 2 intersect, that is, at the base portion of the step portion having a small diameter on the outer periphery of the hub 2. A groove 31 is formed which is larger in radius than the chamfered R surface of the inner ring fitted to the portion and is formed of a single arc that the inner ring does not contact. Therefore, also in this embodiment, it is possible to absorb the deformation due to the excessive tensile load under the static large load by the groove 31 and to alleviate the stress concentration when the static large load is applied. It becomes possible.

  In each of the above embodiments, the cylindrical portion of the shaft end portion of the hub is bent while expanding in the radial direction, pressed against the end surface of the inner ring, and the inner ring is pressed against the step surface and fixed. Although an example of the bearing device is shown, as shown in FIG. 4, for example, a male screw portion 10 is formed at the inner end portion of the hub 2 as in the conventional first example shown in FIG. The tip of the portion 10 protrudes inward from the inner end surface of the inner ring 3, and the inner ring 3 is sandwiched between the nut 11 screwed into the male screw portion 10 and the step surface 12 of the small diameter step portion 8. Thus, the present invention can be applied to a wheel support bearing device of a type in which the inner ring 3 is fixed to a predetermined position of the hub 2. That is, also in the embodiment shown in FIG. 5, the base of the small diameter step portion 8 to which the inner ring 3 is fixed has a larger radius than the chamfered R surface 27 of the inner ring 3 fixed to the step portion, and the inner ring is applied to the base portion. A groove 31 made of a single arc that does not contact is formed. As a result, in this embodiment as well, each groove 31 can absorb deformation caused by an excessive tensile load under a large static load, and the large static load worked. It is possible to reduce the stress concentration at the time.

  The present invention can be applied to those using rolling elements such as tapered rollers, cylindrical rollers, and spherical rollers, in addition to those using balls as rolling elements as shown in the above-described embodiments. However, the present invention can be similarly applied to a wheel support bearing device used for a drive wheel into which a shaft of a constant velocity joint is inserted.

It is sectional drawing of 1st Example of this invention, (a) is the whole sectional drawing, (b) is principal part sectional drawing of (a). It is sectional drawing which shows the further principal part of the Example, (a) shows the 1st aspect of a groove | channel, (b) is a 2nd aspect, (c) is sectional drawing which shows a 3rd aspect. . It is sectional drawing of 2nd Example of this invention. It is sectional drawing of 3rd Example of this invention. It is sectional drawing of a prior art example. It is sectional drawing of another prior art example. It is sectional drawing of another prior art example. (A) is sectional drawing which shows the form of the level | step difference R part in a prior art example, (b) is sectional drawing which shows the other form of the level | step difference R part in a prior art example, (c) is still another example in a prior art example. It is sectional drawing which shows a form.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Wheel bearing apparatus 2 Hub 3 Inner ring 4 Outer ring 5 Rolling element 6 Flange 7 First inner ring raceway 8 Step part 9 Second inner ring raceway 12 Step surface 13 First outer ring raceway 14 Second outer ring raceway 15 Flange 16 Caulking Part 20 Cylindrical part 21 Inner end face 22 Seal ring 27 Chamfer R surface 30 Inner peripheral face 31 Groove
32 Groove inner surface

Claims (3)

A flange for supporting the wheel at the outer end of the outer peripheral surface, a first inner ring raceway formed directly or via a separate inner ring at the intermediate portion, and this first inner ring raceway formed at the inner end portion. A hub having a small-diameter step portion having a smaller outer diameter than the portion, a second inner ring raceway on the outer peripheral surface, an inner ring externally fitted to the small-diameter step portion, and the inner ring on the inner peripheral surface An outer ring forming a first outer ring raceway facing the first inner ring raceway and a second outer ring raceway facing the second inner ring raceway; the first and second inner ring raceways; and the first, first In the wheel support bearing device comprising a plurality of rolling elements provided between each of the two outer ring raceways,
A wheel having a single arc that has a radius larger than a chamfered R surface of a member fitted to the step and is not in contact with the member is formed at a base of the small-diameter step of the hub. Bearing device.   2. The wheel bearing device according to claim 1, wherein an end portion on the radially outer side of the groove is positioned on an outer side in the radial direction with respect to an end portion of the chamfered R surface of the member to be fitted. 2. The wheel bearing device according to claim 1, wherein an end portion on the inner side in the axial direction of the groove is positioned on an inner side in the axial direction with respect to an end portion of the chamfered R surface of the member to be fitted.

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