JP2006153052A - Bearing unit for wheel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bearing unit for a wheel capable of reducing manufacturing costs by omitting partial heat treatment to an internal shaft and outer ring and attaining longer life in a simple structure. <P>SOLUTION: The bearing unit for a wheel comprises an internal shaft 1, an outer ring 2 arranged on a periphery of the internal shaft 1, and rolling bodies 3a and 3b arranged between the internal shaft 1 and outer ring 2 so as to have an angular contact between the internal shaft 1 and outer ring 2. Ring-shaped raceway members 4a and 4b with a sectioned curved shape which are separate members and have the race surfaces for the rolling balls are arranged on an inner peripheral surface 12 of the outer ring 2. An uneven surface section for locking is formed on the peripheral surface of the raceway members 4a and 4b. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a wheel bearing device.

What is conventionally known as a wheel bearing device (hub unit) to which a wheel of an automobile is mounted includes an inner shaft on which a wheel wheel or a brake rotor of a disc brake is mounted, and two rows of rolling elements interposed between the inner shaft Some of them have an outer fitting shape and are provided with a vehicle body side and an outer ring that is fixed. And the raceway surface for rolling elements is formed in two places, the outer peripheral surface of an inner shaft, the outer peripheral surface of the inner ring member externally fitted to the inner shaft, and the inner peripheral surface of the outer ring.
The outer ring and the inner shaft are formed by hot forging a material made of carbon steel such as S55C (carbon steel for machine structural use), and in the raceway surface and the inner shaft that require high hardness. The base portion of the flange portion for attaching the wheel of the wheel is subjected to heat treatment (induction quenching and tempering), thereby improving the performance and extending the life. However, such heat treatment is one of the factors that increase the manufacturing cost. In particular, partial hardening on the inner peripheral surface of the outer ring and the outer peripheral surface of the inner shaft, which has a complicated shape, is difficult to work and the manufacturing cost is very high. There is a problem that it becomes high.
In view of this, for example, Patent Document 1 proposes a configuration in which an inner shaft is formed by cold forging a tubular material, and the manufacturing cost is reduced by reducing the range of cutting and polishing.

JP 2003-290431 A (Claims)

  However, the bearing device described in Patent Document 1 still requires heat treatment of the raceway surface and cannot solve the above problems. Also, when the outer ring and inner shaft formed of carbon steel and the mating member fixed to these are different materials, for example, when the mating member is an aluminum member, the bearing device and the mating member are It is not a configuration that takes into account the electric corrosion that occurs. In other words, when the other member fixed to the wheel bearing device, for example, the knuckle for the outer ring or the wheel for the inner shaft is an aluminum member, the ionization of iron and aluminum is caused by water that has entered the gap formed between them. Due to the difference in tendency, aluminum on the mating member side is corroded and welded to the wheel bearing device, which makes it difficult to remove the bearing device. And when this welding arises, in order to remove a bearing apparatus from a counterpart member, it is struck with a hammer etc., but it has the problem that a bearing apparatus will be damaged by this impact.

  The present invention has been made in view of the above-mentioned problems, and can reduce the manufacturing cost by omitting partial heat treatment on the inner shaft and the outer ring, and can provide a long service life with a simple configuration. It is an object to provide a bearing device for a vehicle.

  In order to achieve the above object, a wheel bearing device of the present invention includes an inner shaft, an outer ring disposed around the inner shaft, and an inner shaft and an outer ring so as to form an angular contact with the inner shaft and the outer ring. A rolling element provided between the inner shaft and the outer ring, on the outer peripheral surface of the inner shaft and the inner peripheral surface of the outer ring. An annular race member having a curved cross section having a raceway surface for the rolling elements is provided, and an uneven surface portion for preventing rotation is formed on the circumferential surface of the raceway member.

According to the wheel bearing device having such a configuration, by making the race member a separate member, heat treatment can be performed on the entire race member before assembly in order to increase the hardness of the raceway surface. It is not necessary to perform partial heat treatment on the inner shaft and the outer ring, the manufacturing cost can be reduced, the equipment cost can be reduced, and a raceway surface having a predetermined hardness can be obtained.
Even if a large load is applied to the track member provided as a separate member on the inner shaft and the outer ring, the track member is never moved in the circumferential direction by the uneven surface portion, and the track member can be firmly attached. With a simple configuration, it is possible to reliably stop the rotation, and the mounting of the track member is very simple, and the number of manufacturing steps can be reduced.
By using the raceway member having a curved cross-section, it is possible to receive a load in the radial direction (radial direction) that acts and a load in the axial direction (axial direction).

  The track member includes a first circumferential portion that receives a load in a radial direction, and a second circumferential portion that is provided from a proximal end portion side of the first circumferential portion and receives a load in an axial direction. The uneven surface portion is preferably formed on a peripheral surface of the first circumferential portion. According to this configuration, the diameter of the first circumferential portion that fits to the inner shaft and the outer ring is obtained by mounting the raceway member so that the convex portion of the uneven surface portion bites into the outer peripheral surface of the inner shaft and the inner peripheral surface of the outer ring. A more effective detent can be achieved by a synergistic effect of the elastic force of the direction and the detent action by increasing the resistance at the uneven surface portion formed on the circumferential surface of the first circumferential portion.

  Further, the rolling element made of a ball is provided on the raceway surface side of the raceway member, and the circumference of the first circumferential portion of the raceway member is more than the axis orthogonal plane passing through the center of the ball. It is preferable that the concavo-convex surface portion is formed in a region on the tip portion side of one circumferential portion. According to this configuration, since the concave and convex surface portion and the raceway contact portion of the ball in the contact angle direction are separated in the axial direction, the raceway contact portion of the raceway member is not distorted by press-fitting in the concave and convex surface portion. In other words, even if some distortion occurs at the tip of the first circumferential portion of the raceway member on which the uneven surface portion is formed, the accuracy of the raceway surface of the raceway member is not impaired, and the bearing accuracy and bearing life are affected. There is nothing.

According to the wheel bearing device of the present invention, by using a race member that is a separate member from the inner shaft and the outer race, the entire race member before assembly can be heat treated to increase the hardness of the raceway surface. As a result, it is not necessary to perform partial heat treatment on the inner shaft and the outer ring, and it is possible to reduce the manufacturing cost and the equipment cost.
Even if a large load acts on the track member, the track member is never moved in the circumferential direction by the uneven surface portion, and the track member can be firmly attached. Furthermore, the accuracy of the raceway surface of the raceway member is not impaired, and reliable rotation prevention is possible with a simple configuration. The assembly of the track member is very simple, and the number of manufacturing steps can be reduced.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a longitudinal sectional view showing a wheel bearing device according to an embodiment of the present invention. This wheel bearing device includes an inner shaft (hub wheel) 1, an outer ring 2 provided around the inner shaft 1, and an inner shaft 1 and an outer ring 2 so as to be in angular contact with both the inner shaft 1 and the outer ring 2. Are provided with two rows of balls 3a and 3b as rolling elements provided so as to be capable of rolling. The two rows of balls 3 a and 3 b are in contact with the inner shaft 1 and the outer ring 2 at a predetermined contact angle Θ (see FIG. 2), and the wheel bearing device is configured to include a double row angular ball bearing 10. ing.

  The wheel bearing device of the present invention has a mounting surface on at least one side of the outer peripheral surface 11 of the inner shaft 1 and the inner peripheral surface 12 of the outer ring 2 in order to configure the raceway surfaces for the balls 3a and 3b. An annular raceway member 4 that is a separate member from the inner shaft 1 and the outer ring 2 and has a raceway surface for rolling elements is provided. In the embodiment of FIG. 1, two track members 4 a and 4 b are provided only on the inner peripheral surface 12 side of the outer ring 2.

  In FIG. 1, an inner shaft 1 is formed at a shaft portion 31 having a circular cross section with the axial center C direction of the bearing device as a longitudinal direction, and one end portion on the outer peripheral side of the shaft portion 31. And a radially outer flange portion 7. And as shown in the principal part sectional view of Drawing 2, inner ring member by which the 1st inner ring track which is the single track is formed in small diameter outer peripheral surface 22 near the other end of shaft part 31 of inner shaft 1 is formed. 9 is externally fitted, and a single second inner ring raceway is formed on the middle-diameter outer peripheral surface 23 in the middle of the shaft portion 31 in the axial direction. The large-diameter outer peripheral surface 24 near one end portion of the shaft portion 31 and the base portion of the flange portion 7 serve as a seal surface of a seal member 35 provided between the outer ring 2 and the base portion. Further, at the other end portion of the shaft portion 31, an outer peripheral end portion is expanded radially outward to form a caulking portion 32, and the inner ring member 9 is secured to the shaft portion 31 by the caulking portion 32.

In FIG. 1, the outer ring 2 includes a cylindrical portion 34 that is coaxial with the inner shaft 1, and a flange portion 33 that is formed radially outward on the outer periphery of the cylindrical portion 34. The wheel bearing device is fixed to the vehicle body (not shown) via the flange portion 33.
On the inner peripheral surface 12 of the cylindrical portion 34 of the outer ring 2, the first and second track members 4 a and 4 b forming the first and second outer ring raceways are axially oriented, and the axial load receiving meat portion of the outer ring 2. 36 is provided. Between the race members 4a and 4b provided on the outer ring 2 side and the first and second inner ring races on the inner shaft 1 side, two rows of balls 3a and 3b and two crown-shaped cages 37a and 37b are provided. And are provided.

  FIG. 3 is a longitudinal sectional view showing another embodiment of the wheel bearing device of the present invention. In the embodiment of FIG. 3, the inner peripheral surface 12 of the outer ring 2 and the outer peripheral surface 11 of the inner shaft 1 are further divided. The third raceway member 4c is externally fitted to the middle-diameter outer peripheral surface 23 in the middle of the axial portion 31 of the shaft portion 31 of the inner shaft 1, and the outer peripheral surface side of the raceway member 4c is a single surface. The second inner ring raceway is used. Other configurations are the same as those in the embodiment of FIG. In addition, the inner ring member 9 to be externally fitted to the inner shaft 1 can be an inner ring used in a conventionally known angular ball bearing, and the inner ring member 9 can be a conventionally used material, for example, It can be stainless steel.

The track members 4a, 4b, and 4c (hereinafter collectively referred to as track members 4) are press-processed products obtained by pressing a plate material so that the overall shape is annular and the cross-section thereof is a curved shape. The material of the raceway member 4 can be a carbon steel plate that can be pressed and can be heat-treated (quenched and tempered), and examples thereof include SK5 and S75CM.
The track members 4a and 4b disposed on the inner peripheral surface 12 side of the outer ring 2 have a concave shape on the inner peripheral surface side to form a track surface, and the track member 4c provided on the outer peripheral surface 11 side of the inner shaft 1 is The outer peripheral surface side is formed into a concave shape to constitute a track surface. And the rolling element which consists of ball | bowl 3a, 3b is provided in the track surface side of this track member 4. As shown in FIG.
Further, since the raceway member 4 is pressed to have a curved cross section, the raceway surface has high dimensional accuracy and good surface condition. Therefore, after the raceway member 4 is assembled, the raceway surface dimension adjustment process is performed. Omission or shortening of dimension adjustment processing time is possible.

FIG. 4 is an explanatory view showing the second race member 4b in the wheel bearing device of FIG. 1, and the race member 4b (4a) on the outer ring 2 side includes a first circumferential portion 5a that receives a radial load, and FIG. The second circumferential portion 6a is provided from the proximal end portion 51 side of the first circumferential portion 5a toward the radially inner side and can receive a load in the axial direction.
FIG. 5 is an explanatory view showing the race members 4b and 4c in the wheel bearing device of FIG. 3, and the race member 4b (4a) on the outer ring 2 side is the same as that shown in FIG. Omitted. The track member 4c on the inner shaft 1 side is provided with a first circumferential portion 5b that receives a load in the radial direction and a radially outward load from the proximal end portion 51 side of the first circumferential portion 5b. And a second circumferential portion 6b capable of receiving the same.

In FIG. 4, the track member 4 b is provided on the inner peripheral surface 12 of the outer ring 2 while being prevented from rotating by an uneven surface portion 18 a formed on the outer peripheral surface of the track member 4 b. Further, the uneven surface portion 18a is formed on the outer peripheral surface of the first circumferential portion 5a of the raceway member 4b. Similarly, the first track member 4a is fixed by being prevented from rotating at the uneven surface portion 18a.
In FIG. 5, a raceway member 4b on the outer ring 2 side is provided in the same manner as in the case of FIG. 4, and the raceway member 4c is further rotated by an uneven surface portion 18b formed on the inner peripheral surface of the raceway member 4c. It is stopped and provided on the outer peripheral surface 11 of the inner shaft 1. Further, the uneven surface portion 18b is formed on the inner peripheral surface of the first circumferential portion 5b of the raceway member 4c.
Further, the track member 4 is preferably fitted into the inner shaft 1 and the outer ring 2 by press-fitting, and the track member 4 can be assembled more firmly.

  FIG. 7 is a modified example of the track member 4b provided on the outer ring 2 side (modified example of FIG. 4). The uneven surface portion 18a passes through the center c of the ball 3b on the outer peripheral surface of the first circumferential portion 5a. It is partially formed in a region closer to the distal end portion 52 of the first circumferential portion 5a than the axis orthogonal plane f. FIG. 8 is a modified example of the track member 4c on the inner shaft 1 side (modified example of FIG. 5). The uneven surface portion 18b is formed at the center c of the ball 3b on the inner peripheral surface of the first circumferential portion 5b. Is partially formed in a region closer to the distal end portion 52 of the first circumferential portion 5b than the axis orthogonal plane f passing through the first circumferential portion 5b. That is, in the raceway member 4 of FIGS. 7 and 8, distortion of the raceway member 4 due to press-fitting in the concave and convex surface portions 18a and 18b is caused only in the portion on the tip portion 52 side of the first circumferential portions 5a and 5b. In addition, the influence of press fitting is suppressed on the raceway surface side formed on the base end portion 51 side. That is, deformation of the contact portions of the balls 3a and 3b on the raceway surface is prevented.

  The concavo-convex surface portions 18a, 18b can be serrated, and the concavo-convex surface portion 18a is continuous with the outer peripheral surface of the track member 4b in the circumferential direction as shown in the cross-sectional view showing the main part of the track member 4b in FIG. It is preferably formed over the entire circumference so that the raceway member 4b is fitted uniformly in the circumferential direction. Moreover, this uneven | corrugated cross-sectional shape may be a square. In addition, the race member 4 is attached to the outer ring 2 and the inner shaft 1 by press-fitting at the concavo-convex surface portions 18a and 18b, but the race member 4 is maintained so that the shape after the press working of the race member 4 is maintained as it is. Is mounted. That is, the shape of the track member 4 after assembling to the inner shaft 1 and the outer ring 2 is made to be substantially the same as the shape of the track member 4 after press working and before assembling. The uneven surface portions 18a and 18b can be simultaneously formed when the track member 4 is formed by a press. Alternatively, it can be formed by cutting after press working.

  Next, the shape of the inner peripheral surface 12 of the cylindrical portion 34 of the outer ring 2 to which the raceway members 4a and 4b are mounted will be described with reference to FIG. 2. The axial center portion of the inner peripheral surface 12 is a shaft that protrudes radially inward. A direction load pressure receiving part 36 is formed, and the pressure receiving part 36 has a trapezoidal cross section in which the axial width dimension gradually decreases inward. Then, the circumferential surfaces on both sides of the pressure receiving meat portion 36 are the second straight inner peripheral surfaces 14 and 14 that are straight in the direction inclined with respect to the axis C, and the opening end portion side of the pressure receiving meat portion 36 is the pressure receiving meat portion. First straight inner peripheral surfaces 13, 13 are formed in a direction parallel to the axial center C continuous from the radially outer side of 36. Moreover, the 1st straight inner peripheral surface 13 and the 2nd straight inner peripheral surface 14 are continuing via the circular arc part. The track members 4a and 4b are press-fitted into both side portions of the pressure-receiving meat portion 36 from both opening end portions of the cylindrical portion 34 of the outer ring 2, and as shown in FIGS. Further, the outer peripheral surface of the first circumferential portion 5a of the raceway member 4b (4a) is in close contact with the uneven surface portion 18a, and the outer peripheral surface of the second circumferential portion 6a is in close contact with the second straight inner peripheral surface 14. In addition, the 1st circumference part 5a in which the uneven | corrugated surface part 18a is formed closely_contact | adheres to the 1st straight inner peripheral surface 13 by the smooth surface which does not have an uneven | corrugated waveform. Further, the track member 4a has a slight gap between the arc portion between the first straight inner peripheral surface 13 and the second straight inner peripheral surface 14 and the central portion of the outer peripheral surface of the track members 4a and 4b. , 4b are arranged. Thereby, when the track members 4a and 4b are press-fitted, the outer peripheral surfaces of the track members 4a and 4b can be reliably brought into contact with the first straight inner peripheral surface 13 and the second straight inner peripheral surface 14.

  The shape of the outer peripheral surface 11 of the inner shaft 1 on which the raceway member 4c is mounted will be described with reference to FIG. 3. The outer peripheral surface 11 of the inner shaft 1 protrudes from the outer peripheral surface 23 of the inner diameter in the radial direction and protrudes radially outward. A second axial load pressure receiving portion 38 having a stepped shape to 24 is formed near one end portion of the inner shaft 1, and the axial size of the pressure receiving portion 38 is gradually reduced outward in the radial direction. It is formed to do. A part of the medium-diameter outer peripheral surface 23 is a first straight outer peripheral surface 26 that is straight in a direction parallel to the axis C, and the inclined side peripheral surface of the pressure-receiving meat portion 38 is constant with respect to the axis C. The second straight outer peripheral surface 27 is straight in a direction inclined at an inclination angle. The track member 4c is externally fitted by press-fitting from the other end side of the inner shaft 1 to the side portion of the pressure-receiving meat portion 38, and as shown in FIGS. 5 and 8, the first straight outer periphery of the inner shaft 1 is fitted. The inner peripheral surface of the first circumferential portion 5b of the raceway member 4c is in close contact with the surface 26 at the uneven surface portion 18b, and the inner peripheral surface of the second circumferential portion 6b is in close contact with the second straight outer peripheral surface 27. In addition, the 1st circumference part 5b in which the uneven | corrugated surface part 18b was formed closely_contact | adheres to the 1st straight outer peripheral surface 26 by the smooth surface which does not have an uneven | corrugated waveform.

4 and 7, in the raceway member 4b (4a), the outer circumferential surface of the first circumferential portion 5a contacts the first straight inner circumferential surface 13 formed on the inner circumferential surface 12 of the outer ring 2. The third straight outer peripheral surface 16 is straight in a direction parallel to the bearing axis C, and an uneven surface portion 18 a is formed on the third straight outer peripheral surface 16. The outer circumferential surface of the second circumferential portion 6a is straight in the direction inclined with respect to the bearing axis C that is in surface contact with the second straight inner circumferential surface 14 formed on the inner circumferential surface 12 of the outer ring 2. 4 straight outer peripheral surface 17 is provided.
5 and 8, also in the third raceway member 4c, the inner circumferential surface of the first circumferential portion 5b contacts the first straight outer circumferential surface 26 formed on the outer circumferential surface 11 of the inner shaft 1. A third straight inner peripheral surface 28 is provided, and an uneven surface portion 18 b is formed on the third straight inner peripheral surface 28. And it has the 4th straight inner peripheral surface 29 in surface contact with the 2nd straight outer peripheral surface 27 formed in the outer peripheral surface 11 of the inner shaft 1 in the inner peripheral surface 29 of the 2nd circumferential part 6b.

  In the present invention, the outer ring 2 is preferably made of the same material as the mating member connected to the outer ring 2. For example, when the material of the attachment part of the mating member on the vehicle body side to be connected is made of aluminum, the outer ring 2 is also made of aluminum. Thereby, electrolytic corrosion does not occur between the two due to the water that has entered the gap between the bearing device and the counterpart member. Furthermore, the outer ring 2 can be made of an aluminum casting, and productivity can be increased. That is, the track members 4a and 4b can be mounted on the outer ring 2 made of cast aluminum that does not undergo finishing processing such as cutting or polishing to form the track surface with respect to the inner peripheral surface 12. Thus, the processing cost can be reduced, the production facility can be omitted, and the productivity can be improved.

Further, the inner shaft 1 can be made of the same material as the mating member to be attached, and the inner shaft 1 can be made of aluminum. In this case, as shown in FIG. 3, a track member 4 c, which is a separate member, is provided on the outer peripheral surface of the inner shaft 1. Thus, weight reduction of the bearing device can be achieved by making the material of the inner shaft 1 and the outer ring 2 aluminum.
The material of the outer ring 2 and the inner shaft 1 is the same type as the mating member to which the material is attached. However, the term “same type” as used herein means that both the materials and components are the same, and the materials and components are different. Includes the case where ionization tendency is the same (substantially the same).
In other words, the present invention can be applied even if the material of the inner shaft 1 and the outer ring 2 cannot be increased in hardness by heat treatment, such as aluminum. It is possible to select materials that are easy to process, materials with good productivity, and functional materials.

  Further, the wheel bearing device of the present invention is not limited to the form shown in the drawings, and may be of other forms within the scope of the present invention, and FIGS. 1 to 3 have been described as wheel bearing devices for driven wheels. However, although not shown, the present invention can also be applied to a wheel bearing device on the drive wheel side.

1 is a longitudinal sectional view showing a wheel bearing device according to an embodiment of the present invention. It is sectional drawing which shows the principal part of the wheel bearing apparatus which concerns on this invention. It is a longitudinal cross-sectional view which shows the wheel bearing apparatus which concerns on other embodiment of this invention. It is explanatory drawing which shows the track member in the wheel bearing apparatus of FIG. It is explanatory drawing which shows the track member in the wheel bearing apparatus of FIG. It is a cross-sectional view which shows the principal part of a track member. It is explanatory drawing which shows the modification of a track member. It is explanatory drawing which shows the modification of a track member.

Explanation of symbols

Reference Signs List 1 inner shaft 2 outer ring 3a ball 3b ball 4 raceway member 5a first circumferential portion 5b first circumferential portion 6a second circumferential portion 6b second circumferential portion 11 outer circumferential surface 12 inner circumferential surface 18 uneven surface portion c center f axis Orthogonal plane

Claims (3)

  A wheel bearing comprising: an inner shaft; an outer ring disposed around the inner shaft; and a rolling element provided between the inner shaft and the outer ring so as to form an angular contact with the inner shaft and the outer ring. In the apparatus, an annular track having a curved section having a raceway surface for the rolling element, which is a member different from the inner shaft and the outer ring, on at least one side of the outer peripheral surface of the inner shaft and the inner peripheral surface of the outer ring. A wheel bearing device, wherein a member is provided, and an uneven surface portion for preventing rotation is formed on a peripheral surface of the raceway member.   The track member includes a first circumferential portion that receives a load in a radial direction, and a second circumferential portion that is provided from a proximal end side of the first circumferential portion and receives a load in an axial direction, 2. The wheel bearing device according to claim 1, wherein the uneven surface portion is formed on a peripheral surface of the first circumferential portion.   The rolling element comprising a ball is provided on the raceway surface side of the raceway member, and the first circle is a circumferential surface of the first circumferential portion of the raceway member and is orthogonal to the axis orthogonal to the center of the ball. The wheel bearing device according to claim 2, wherein the concavo-convex surface portion is formed in a region on a distal end side of the peripheral portion.

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