JP2008261384A - Bearing device for wheel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bearing device for a wheel in which the life of bearings is prolonged by eliminating the portions deteriorated in structure by heat treatment and improving the lubricity. <P>SOLUTION: This bearing device for a wheel comprises an outer member 15 having double rows of outer rolling surfaces 10a, 10b formed integrally with each other on the inner peripheral surface. A predetermined hard layer 12 is formed on the surfaces of the double rows of outer rolling surfaces 10a, 10b by induction hardening. A cylindrical shoulder part 16 is formed between the double rows of outer rolling surfaces 10a, 10b of the outer member 15 by forging. An annular cutout part 17 is formed from the double rows of outer rolling surfaces 10a, 10b to the shoulder part 16 by cutting the hardened steel after the hardening. The cutout part 17 is so formed to a predetermined width that at least all the area of the hardened layer 12 is removed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a wheel bearing device that rotatably supports a wheel of an automobile or the like with respect to a suspension device.

  2. Description of the Related Art Wheel bearing devices for vehicles such as automobiles include those for driving wheels and those for driven wheels. In particular, a wheel bearing device that rotatably supports a wheel with respect to a suspension device of an automobile has been reduced in weight for improving fuel consumption, not to mention cost reduction. As a typical example of the conventional structure, a wheel bearing device for a driven wheel as shown in FIG. 6 is known.

  This wheel bearing device includes a hub wheel 50 and a wheel bearing 51 fixed to the hub wheel 50, and is referred to as a second generation. 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, and the side closer to the center is referred to as the inner side.

  The hub wheel 50 integrally has a wheel mounting flange 52 for mounting a wheel (not shown) at one end, a shaft portion 53 extending in the axial direction from the wheel mounting flange 52, and an end portion of the shaft portion 53. A male screw 53a is formed on the top.

  The wheel bearing 51 includes an outer member 54 having double-row outer rolling surfaces 54a and 54b formed on the inner periphery, and an inner rolling surface 55a facing the double-row outer rolling surfaces 54a and 54b on the outer periphery. , 55b, a pair of inner rings 55, 55, and a double-row angular ball bearing comprising double-row balls 56, 56 accommodated between both rolling surfaces via a retainer 57 so as to roll freely. Is configured. The wheel bearing 51 is detachably fixed to the hub wheel 50 by a fixing nut 58 fastened to the male screw 53a.

  The outer member 54 is integrally formed with a vehicle body mounting flange 54c on the outer periphery for mounting to the vehicle body (not shown). The vehicle body mounting flange 54c is normally formed at a position substantially corresponding to the outer side rolling surface 54a on the inner side toward the inner side where the load is increased. A chamfered portion 60 is formed at the edge portion from the inner side outer rolling surface 54a to the shoulder portion (inner diameter portion) 59, and the edge portion from the outer side outer rolling surface 54b to the shoulder portion 59 is chamfered. The part is not formed.

The double row outer rolling surfaces 54a and 54b of the outer member 54 are hardened by induction hardening. In this case, the inner outer rolling surface 54a near the vehicle body mounting flange 54c is deprived of heat. It is easy, that is, the outer side rolling surface 54a on the inner side is harder to burn than the outer side rolling surface 54b on the outer side. Therefore, although quenching is performed under relatively strong conditions, since the chamfered portion 60 is formed at the edge portion from the outer side rolling surface 54a on the inner side to the shoulder portion 59, heat concentrates on the edge portion. The organization can be prevented from deteriorating.
Japanese Patent No. 38221979

  In such a conventional wheel bearing device, a chamfered portion 60 is formed at the edge portion from the outer rolling surface 54a to the shoulder 59 in the inner side outer rolling surface 54a where quenching is performed under relatively strong conditions. Since it is formed, it is possible to prevent the heat from concentrating on the edge portion and deteriorating the tissue. However, even if the heat treatment conditions and the shape / dimensions of the chamfered portion 60 are sufficiently controlled so as not to cause cracking during induction hardening, the crystal grains may become coarse due to overheating. When the structure becomes coarse, the rolling fatigue life is reduced. In addition, when riding on the shoulder, there was a limit in trying to take measures against the short life due to edge loading with the shape of the shoulder. Here, shoulder climbing refers to a phenomenon in which the contact ellipse of the ball 56 deviates from the outer rolling surface 54a, and edge load refers to excessive stress concentration occurring at the corners, etc. The phenomenon that becomes one of.

  The present invention has been made in view of such a conventional problem, and provides a wheel bearing device in which a portion whose structure is deteriorated by heat treatment is eliminated and lubricity is improved to extend the life of the bearing. For the purpose.

  In order to achieve such an object, the invention described in claim 1 of the present invention has a vehicle body mounting flange integrally attached to the vehicle body on the outer periphery, and a double row outer rolling surface is integrated on the inner periphery. An outer member formed, an inner member having a double row inner rolling surface facing the outer row rolling surface of the double row on the outer periphery, and both rolling of the inner member and the outer member A double row rolling element accommodated in a rollable manner via a cage between the surfaces, and the outer rolling surface of the double row is subjected to a hardening treatment comprising a predetermined hardened layer on the surface by induction hardening. In the wheel bearing device, a cylindrical shoulder is formed by forging between double row outer rolling surfaces of the outer member, and the shoulder is machined after the hardening treatment.

  As described above, the outer member having the double row outer rolling surface formed integrally on the inner periphery is provided, and the double row outer rolling surface is subjected to a hardening process including a predetermined hardened layer on the surface by induction hardening. In the wheel bearing device, a cylindrical shoulder portion is formed by forging between the double-row outer rolling surfaces of the outer member, and this shoulder portion is machined after the hardening treatment. Even if the edge of the double-row outer raceway and the shoulder is overheated and the surface crystal grains are coarsened and deteriorated, it can be reliably removed, and the bearing short due to cracks and chipping due to burning cracks. In addition to preventing the life, it is possible to prevent the occurrence of burning cracks in the shoulder portions having different shrinkage amounts during quenching due to the difference in carbon amount due to decarburization of the forged skin portion.

  Preferably, as in the invention described in claim 2, an annular notch is formed from the outer surface of the double row to the shoulder, and at least the range of the hardened layer is removed from the notch. If it is formed to have a predetermined width, the notch will function as a grease pocket, and the grease sealed inside the bearing will be aligned in a row along the notch by gravity and centrifugal force. Therefore, the lubricating environment can be maintained in a good state, and the life of the bearing can be extended.

  Further, as in the invention according to claim 3, if a predetermined chamfered portion is formed by machining after the hardening process at the edge portion from the outer rolling surface of the double row to the shoulder portion, It is possible to prevent the edge load from occurring at the edge portion and to prevent the tissue from deteriorating due to heat concentration at the edge portion.

  Further, as in the invention described in claim 4, the machining may be hardened steel cutting, and as in the invention described in claim 5, the machining is performed outside the double row. Grinding performed simultaneously with the rolling surface may be used.

  A wheel bearing device according to the present invention has an outer member integrally formed with a vehicle body mounting flange for mounting to a vehicle body on the outer periphery, a double row outer rolling surface formed integrally on the inner periphery, and an outer periphery. An inner member in which a double row inner rolling surface facing the outer row rolling surface of the double row is formed, and rolling between the both rolling surfaces of the inner member and the outer member via a cage. In the wheel bearing device, the outer member is provided with a double row rolling element freely accommodated, and the outer rolling surface of the double row is subjected to a hardening treatment including a predetermined hardened layer on the surface by induction hardening. A cylindrical shoulder is formed by forging between the double-row outer rolling surfaces of the two rows, and this shoulder is machined after the hardening treatment. Even if the edge part is overheated and the surface crystal grains are coarsened and deteriorated, it is surely removed. It can prevent the short life of the bearing due to cracks and cracks due to burning cracks, and also causes cracking at the shoulder with different shrinkage during quenching due to the difference in carbon content due to decarburization of the forged skin. Can be prevented.

  An outer member integrally having a vehicle body mounting flange to be attached to the vehicle body on the outer periphery, a double row outer rolling surface formed integrally on the inner periphery, and a wheel mounting flange for mounting a wheel on one end A hub wheel integrally formed and having an inner rolling surface facing one of the outer rolling surfaces of the double row on the outer periphery, and a small-diameter step portion extending in the axial direction from the inner rolling surface, and the hub wheel An inner member made of an inner ring that is press-fitted into a small-diameter step portion of the inner diameter through a predetermined squeeze and has an inner rolling surface that faces the other of the outer rolling surfaces of the double row on the outer periphery, and the inner member A double row of balls accommodated in a rolling manner between both rolling surfaces of the outer member via a cage, and the outer rolling surface of the double row is subjected to induction hardening from a predetermined hardened layer on the surface. In the wheel bearing device subjected to the hardening treatment, the outer side of the double row of the outer members A cylindrical shoulder is formed by forging between the running surfaces, and an annular notch is formed by quenching steel cutting after the hardening treatment from the outer row rolling surface of the double row to the shoulder. In addition, it is formed in a predetermined width so that at least the range of the hardened layer is completely removed.

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 (a) is an enlarged sectional view showing a single outer member of FIG. 1, and FIG. It is an expanded sectional view which shows the modification of a).

  This wheel bearing device is referred to as the third generation on the driven wheel side, and is a double row rolling element (ball) accommodated between the inner member 1 and the outer member 10 and between both members 1 and 10 so as to roll freely. 6 and 6 are provided. The inner member 1 includes a hub ring 2 and an inner ring 3 that is press-fitted into the hub ring 2 through a predetermined scissors.

  The hub wheel 2 integrally has a wheel mounting flange 4 for mounting a wheel (not shown) at an end on the outer side, and a hub bolt for fixing the wheel at a circumferentially equidistant position of the wheel mounting flange 4. 5 is planted. Further, one (outer side) inner rolling surface 2a is directly formed on the outer periphery of the hub wheel 2, and a small-diameter step portion 2b extending in the axial direction from the inner rolling surface 2a is formed. And the inner ring | wheel 3 in which the inner side rolling surface 3a of the other (inner side) was formed in the outer periphery is press-fit in this small diameter step part 2b, and also the edge part of the small diameter step part 2b is plastically deformed to radial direction outward. The inner ring 3 is fixed in the axial direction by the formed caulking portion 2c to form a back-to-back type double row angular ball bearing.

  The hub wheel 2 is formed of medium and high carbon steel containing carbon of 0.40 to 0.80% by weight, such as S53C, and includes a seal land portion in which an outer side inner rolling surface 2a and an outer side seal 8 described later are in sliding contact. Further, the surface hardness is set in the range of 58 to 64 HRC by induction hardening over the small-diameter step portion 2b. The caulking portion 2c is an unquenched portion having a material surface hardness of 25 HRC or less after forging. On the other hand, the inner ring 3 and the rolling element 6 are made of high carbon chrome bearing steel such as SUJ2, and are hardened in the range of 58 to 64 HRC up to the core by quenching. Thereby, not only the wear resistance of the seal land portion is improved, but also the strength of the hub wheel 2 is improved, and the fretting wear on the fitting surface of the inner ring 3 is suppressed, thereby improving the durability. Moreover, the workability of the caulking portion 2c can be improved, and the occurrence of cracks and the like due to plastic deformation can be prevented.

  The outer member 10 integrally has a vehicle body mounting flange 10c for mounting to the vehicle body (not shown) on the outer periphery, and faces the double row inner rolling surfaces 3a, 2a of the inner member 1 on the inner periphery. Double row outer rolling surfaces 10a and 10b are integrally formed. Similar to the hub wheel 2, the outer member 10 is made of medium and high carbon steel containing 0.40 to 0.80% by weight of carbon such as S53C, and is formed between the rolling surfaces 10b, 2a and 10a, 3a. The rolling elements 6 and 6 of a row | line are accommodated and these rolling elements 6 and 6 of a double row are hold | maintained so that rolling is possible by the holder | retainers 7 and 7. FIG. Seals 8 and 9 are attached to the opening of the annular space formed between the outer member 10 and the inner member 1, and leakage of lubricating grease sealed inside the bearing and rainwater and dust from the outside. Etc. are prevented from entering the inside of the bearing.

  Here, the wheel bearing device referred to as the third generation in which the inner raceway surface 2a is directly formed on the outer periphery of the hub wheel 2 is illustrated, but the wheel bearing device according to the present invention is not limited to such a structure. For example, although not shown, the outer joint member of the constant velocity universal joint includes a second generation structure having a body mounting flange on the outer periphery of the outer member and a pair of inner rings press-fitted into the small-diameter step portion of the hub wheel. May be a united fourth generation structure. In addition, although the double row angular contact ball bearing which used the rolling elements 6 and 6 as the ball was illustrated, it is not restricted to this, The double row tapered roller bearing which uses the tapered roller for the rolling element 6 may be sufficient.

  Here, as shown in FIG. 2A, the outer member 10 has a cylindrical shoulder portion 11 formed by forging between the double row outer rolling surfaces 10a and 10b. Then, after the double row outer rolling surfaces 10a and 10b are turned, the hardened layer 12 is formed with a surface hardness of 58 to 64 HRC by induction hardening (indicated by cross-hatching in the figure). Furthermore, in this embodiment, the shoulder portion 11 is formed to have a predetermined inner diameter by machining such as hardened steel cutting (indicated by a two-dot chain line in the figure). Thereby, even if the edge part 13 of the double row outer side rolling surfaces 10a and 10b and the shoulder part 11 overheats by induction hardening, and the surface crystal grain coarsens and deteriorates, it can remove reliably. Further, it is possible to prevent a short life of the bearing due to cracks and cracks due to quench cracks, and to cause cracks in the shoulder 11 having different shrinkage amounts during quenching due to a difference in carbon amount due to decarburization of the forged skin part. Can be prevented.

  FIG. 2B shows a modified example of FIG. 2A. Here, the hardened layer 12 is formed in the double row outer rolling surfaces 10a and 10b by induction hardening in a surface hardness range of 58 to 64 HRC. (Indicated by cross-hatching in the figure) After that, arcuately formed with a predetermined radius of curvature R at the edge portion from the shoulder portion 11 and the double row outer rolling surfaces 10a, 10b to the shoulder portion 11 by quenching steel cutting. A chamfered portion 14 is formed (indicated by a two-dot chain line in the figure). Thereby, it is possible to prevent the edge load from being generated at the edge portion due to the riding on the shoulder, and it is possible to prevent the heat from being concentrated on the edge portion and deteriorating the tissue. Here, the curvature radius R of the chamfered portion 14 is set to a range of 0.15 to 2.0R, preferably 0.45 to 0.7R, and each connecting portion is formed smoothly. If the radius of curvature R is less than 0.15R, the rolling element 6 is easily scratched. On the other hand, if the radius of curvature R exceeds 2.0R, the contact ellipse of the rolling element 6 rides and rolls outward. It is not preferable because it is easily detached from the surfaces 10a and 10b.

  Here, the chamfered portion 14 exemplifies a so-called R chamfer having an arc shape, but is not limited thereto, and may be a so-called C chamfer inclined with respect to the shoulder portion 11 in a range of 30 to 50 °. . Moreover, although the chamfered part 14 was formed by quenching steel cutting, you may form simultaneously with the double row outer side rolling surfaces 10a and 10b by grinding.

  FIG. 3A is an enlarged cross-sectional view of a single outer member showing a second embodiment of the wheel bearing device according to the present invention, FIG. 3B is an enlarged view of the main part of FIG. ) Is an enlarged cross-sectional view showing a modification of the single outer member in FIG. 3A, and FIG. 5B is an enlarged view of the main part of FIG. This embodiment is different from the above-described first embodiment (FIG. 2) only in the shape of the shoulder, and the same reference numerals are assigned to other identical parts, and detailed description thereof is omitted.

  The outer member 15 has a cylindrical shoulder 16 formed by forging between the double-row outer rolling surfaces 10a and 10b, and the double-row outer rolling surfaces 10a and 10b are turned. A hardened layer 12 is formed by quenching so that the surface hardness is in the range of 58 to 64 HRC (indicated by cross-hatching in the figure). An annular notch 17 is formed by quenching steel cutting from the double row outer rolling surfaces 10a, 10b to the shoulder 16. As shown in (b), the notch 17 is formed to have a predetermined width so that at least the entire range of the hardened layer 12 is removed (indicated by a two-dot chain line in the figure). Thereby, even if the edge part 13 of the double row outer side rolling surfaces 10a and 10b and the shoulder part 16 is overheated by induction hardening and the crystal grains on the surface are coarsened and deteriorated, it can be reliably removed. Further, it is possible to prevent a short life of the bearing due to cracks and cracks caused by burning cracks.

  FIG. 4A shows a modification of FIG. Here, the hardened layer 12 is formed in the double row outer rolling surfaces 10a and 10b by induction hardening in a surface hardness of 58 to 64 HRC (indicated by cross hatching in the figure), and then by quenching steel cutting. The chamfered portion 14 is formed at the edge portion extending from the double row outer rolling surfaces 10a, 10b to the shoulder portion 16, and the annular notch portion is cut by quenching steel with a predetermined width from the chamfered portion 14 to the shoulder portion 16. 17 is formed (indicated by a two-dot chain line in the figure). As a result, it is possible to prevent an edge load from being generated at the edge portion by climbing over the shoulder, maintain the lubrication environment in a favorable state, and further increase the life of the bearing.

  Further, as shown in FIG. 5, the notch portion 17 functions as a grease pocket, and the grease enclosed in the bearing smoothly moves along the notch portion 17 along the notch portion 17 due to gravity and centrifugal force. Since it moves to rolling surface 10a, 10b, a lubrication environment can be maintained in a favorable state and lifetime improvement of a bearing can be aimed at.

  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.

  A wheel bearing device according to the present invention has a second-generation to fourth-generation wheel having an outer member integrally including a vehicle body mounting flange on the outer periphery and having a double row outer rolling surface formed on the inner periphery. It can be applied to a bearing device for use.

It is a longitudinal section showing a 1st embodiment of a bearing device for wheels concerning the present invention. (A) is an expanded sectional view which shows the outward member single-piece | unit of FIG. (B) is an expanded sectional view showing a modification of (a). (A) is an expanded sectional view of the outer member simple substance which shows 2nd Embodiment of the wheel bearing apparatus which concerns on this invention. (B) is the principal part enlarged view of (a). (A) is an expanded sectional view which shows the modification of the outer member single-piece | unit of Fig.3 (a). (B) is the principal part enlarged view of (a). It is explanatory drawing which shows the flow of the grease of the wheel bearing apparatus which concerns on this invention. It is a longitudinal cross-sectional view which shows the conventional wheel bearing apparatus.

Explanation of symbols

1 ... inner member 2 ... hub wheels 2a, 3a ... inner rolling surface 2b ... small diameter step 2c ········································ 3・ ・ ・ ・ ・ ・ Rolling element 7 ・ ・ ・ ・ ・ ・ ・ ・ ・ Cage 8, 9 ・ ・ ・ ・ ・ ・ ・ ・ Seal 10, 15 ・ ・ ・ Outer member 10a, 10b ・ ・ ・ Outward rolling Running surface 10c ······ Body mounting flanges 11, 16 ··· Shoulder portion 12 ··· Hardened layer 13 ··· Edge portion 14 ··· .... Chamfered part 17 ... Notch part 50 ... Hub wheel 51 ... Wheel bearing 52 ... Wheel mounting flange 53 ... Shaft 53a ... -Male thread 54 ... Outer members 54a, 54b ... Outer rolling surface 54c ... Car body mounting flange 55 ... Inner rings 55a, 55b ...・ Inner rolling surface 56 ・ ・ ・ ・ ・ ・ ・ ・ Ball 57 ・ ・ ・ ・ ・ ・ ・ ・ Retainer 58 ・ ・ ・ ・ ・ ・ ・ ・ Fixing nut 59 ・ ・ ・ ・ ・ ・ ・ ・ Shoulder 60 ・..... Chamfered part R ..... curvature radius

Claims (5)

An outer member integrally having a vehicle body mounting flange for being attached to the vehicle body on the outer periphery, and an outer rolling surface of a double row integrally formed on the inner periphery;
An inner member in which a double row inner rolling surface facing the outer row rolling surface of the double row is formed on the outer periphery;
A double-row rolling element accommodated between the rolling surfaces of the inner member and the outer member via a cage so as to freely roll,
In the wheel bearing device in which the outer surface of the double row is subjected to a hardening treatment including a predetermined hardening layer on the surface by induction hardening,
A wheel bearing device, wherein a cylindrical shoulder portion is formed by forging between double row outer rolling surfaces of the outer member, and the shoulder portion is machined after the hardening treatment.   An annular notch is formed from the double row outer rolling surface to the shoulder, and the notch is formed to have a predetermined width so that at least the range of the hardened layer is removed. The wheel bearing device according to 1.   3. The wheel bearing device according to claim 1, wherein a predetermined chamfered portion is formed by machining after the hardening process at an edge portion extending from the double row outer rolling surface to a shoulder portion.   The wheel bearing device according to claim 1, wherein the machining is hardened steel cutting.   The wheel bearing device according to any one of claims 1 to 3, wherein the machining is grinding performed simultaneously with the double row outer rolling surface.

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