JP2006002829A - Bearing device for wheel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bearing device for a wheel capable of miniaturizing the device, reducing its weight, and increasing and stabilizing slip torque of a hub bolt to increase reliability. <P>SOLUTION: This bearing device for the wheel is constituted in such a way that a wheel mounting flange 13 is composed of a plurality of partial flanges 13a protruding radially from a basic part with substantially same width as that of a forming part by cutting out a part except the vicinity of a bolt insertion hole 6a, the bolt insertion hole 6a is provided in the partial flange 13a, and the hub bolt 7 forming serration 7a in its neck part is pressed into the bolt insertion hole 6a. A cross sectional shape of a tooth flank of the serration 7a is formed into substantially trapezoidal shape having a flat part at the outside diameter. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a wheel bearing device for rotatably supporting a wheel of an automobile or the like with respect to a suspension device, and more particularly to a wheel bearing device having an increased slip torque of a hub bolt installed on a wheel mounting flange. .

  In recent years, demands for improving fuel efficiency have been severe from the viewpoint of resource saving or pollution. In automobile parts, the weight reduction of wheel bearing devices has been attracting attention as a factor to meet such demands and has been strongly desired for a long time. In particular, among vehicles such as automobiles, light vehicles such as light four-wheel vehicles or small cars are increasingly demanded for light weight as well as cost reduction. Under such circumstances, there have been various proposals related to wheel bearing devices that have been reduced in weight. However, in a wheel bearing device that supports a wheel rotatably together with weight reduction, it is also an important factor to suppress NVH (noise vibration harshness), which is contrary to this weight reduction.

  Among these NVHs, in particular, regarding the low frequency unpleasant noise generated when the brake is operated when the vehicle is running at low speed, the so-called brake judder, the clear cause has not been investigated yet. It has been pointed out that the hub and brake rotor are insufficiently fixed. These wheel hubs and brake rotors are fixed by hub bolts planted on the wheel mounting flanges of the hub wheels. If the fixing force (slip torque) of the hub bolts is small, the wheel hubs and brake rotors are relatively weak during low-speed driving. It is thought that chatter vibrations are generated and brake judder is generated by the vibrations.

  In order to fix the hub bolt to the wheel mounting flange, a serration is usually formed on the neck of the hub bolt, and the outer diameter of this serration is formed larger than the inner diameter of the bolt insertion hole, and press-fitted so that the serration bites into the bolt insertion hole. Has been. In order to increase the slip torque of the hub bolt, the press-fitting allowance is set large. However, as the press-fitting allowance increases, there is a risk that the distortion of the wheel mounting flange increases and the surface runout deteriorates, and this surface runout is not preferable because it causes the brake judder.

  In view of this, there has been known one that increases the slip torque of the hub bolt and reduces the distortion of the flange due to the press-fitting of the hub bolt. As shown in FIG. 6, this wheel bearing device has an outer peripheral body 51b integrally attached to the suspension device 50 on the outer periphery, and outer rows 51a, 51a having double rows of outer rolling surfaces 51a, 51a formed on the inner periphery. One inner rolling surface that integrally has a side member 51 and a wheel mounting flange 52 for mounting a wheel (not shown) at one end and faces the double-row outer rolling surfaces 51a, 51a on the outer periphery. 53a, a hub wheel 53 formed with a cylindrical small-diameter step portion 53b extending in the axial direction from the inner raceway surface 53a, and a small-diameter step portion 53b of the hub wheel 53, and are inserted into the outer periphery of the double row. An inner member 55 comprising an inner ring 54 formed with the other inner rolling surface 54a opposite to the rolling surfaces 51a, 51a, and the inner member 55 and the outer member 51 are accommodated so as to be rollable. Double row rolling elements (balls) 56, 56 It is equipped with a.

  As shown in FIG. 7A, bolt insertion holes 58 into which the hub bolts 57 are press-fitted are formed in the circumference of the wheel mounting flange 52 at equal intervals. On the other hand, the hub bolt 57 is formed with two serrations 59 and 60 that are arranged in the axial direction at the neck portion and have a spire-shaped cross section as shown in FIG. Here, the front side serration 59 has an outer diameter that is press-fitted into the bolt insertion hole 58 at a predetermined press-fitting allowance with respect to the press-fitting direction, and the rear-side serration 60 is smaller than the press-fitting allowance with respect to the press-fitting direction. It is assumed that the outer diameter is press-fitted in the bill. Then, the rear side serration 60 is press-fitted into the inner surface of the bolt insertion hole 58 whose diameter is reduced by a springback phenomenon of the bolt insertion hole 58 after the front side serration 59 is passed through the bolt insertion hole 58 while being press-fitted. .

  That is, when the hub bolt 57 having the two-stage serrations 59 and 60 is press-fitted into the bolt insertion hole 58, the front serration 59 of the hub bolt 57 temporarily enlarges the hole diameter of the bolt insertion hole 58 and the bolt insertion hole 58 The front serration 59 is transferred and formed on the inner surface, but when the front serration 59 passes, the hole diameter is immediately reduced due to the springback phenomenon. After that, when the rear side serration 60 of the hub bolt 57 enters the bolt insertion hole 58, the rear side serration 60 is inserted into the serration inside the bolt insertion hole 58 with a required press-fitting allowance. .

As described above, in the process of press-fitting the hub bolt 57 into the bolt insertion hole 58, the wheel mounting flange 52 is temporarily distorted when passing through the front side serration 59, but after the front side serration 59 passes, By returning to the original state due to the back phenomenon, the deformation of the wheel mounting flange 52 can be suppressed to a small level with less distortion. Then, since the rear side serration 60 stops in the bolt insertion hole 58, the hub bolt 57 is prevented from rotating by the biting action of the rear side serration 60 with respect to the bolt insertion hole 58.
JP 2001-253205 A

  However, when the front side serration 59 passes through the bolt insertion hole 58, the front side serration 59 returns to its original state due to its springback phenomenon, and the deformation is reduced and the deformation of the wheel mounting flange 52 can be suppressed to a small level. Since it stops in the insertion hole 58, it is said that the hub bolt 57 is prevented from rotating by the biting action of the rear side serration 60 with respect to the bolt insertion hole 58. In such a conventional wheel bearing device, however, The front side serration 59 itself of the hub bolt 57 is also partly scraped off during the press-fitting process, and the slip torque of the hub bolt 57 is substantially determined by the press-fitting allowance of the front serration 59 having the larger press-fitting allowance. Even if the deformation of the wheel mounting flange 52 is suppressed, Increase of lip torque can not be expected too much. In recent years, with the aim of reducing the weight of the wheel mounting flange, the wheel mounting flange has a reduced thickness around the bolt insertion hole 58, and the above-described springback phenomenon is excessive. There was a risk that the slip torque of the hub bolt 57 could be reduced due to dimensional variation.

  The present invention has been made in view of such a conventional problem, and provides a wheel bearing device that improves the reliability by reducing the size and weight of the device and increasing and stabilizing the slip torque of the hub bolt. The purpose is to do.

  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 formed on the inner periphery, and an outer rolling surface of the double row on the outer periphery. An inner member formed with opposing double-row inner rolling surfaces; and a double-row rolling element housed in a freely rolling manner between the inner member and the outer member. A wheel mounting flange is integrally provided on either the inner member or the outer member, and a bolt insertion hole is formed in the wheel mounting flange and a serration is formed on the neck portion. In the wheel bearing device press-fitted into the wheel, a configuration is adopted in which the cross-sectional shape of the tooth surface of the serration is formed in a substantially trapezoidal shape having a substantially flat portion on the outer diameter.

  Thus, in the wheel bearing device in which the bolt insertion hole is drilled in the wheel mounting flange and the hub bolt with the serration formed in the neck is press-fitted into the bolt insertion hole, the cross-sectional shape of the tooth surface of the serration has an outer diameter. Since the hub bolt is press-fitted into the bolt insertion hole, it is possible to prevent the tooth surface of the serration from being scraped and its shape to be collapsed. Even with the same number of teeth and the same press-fitting allowance, the tooth width is substantially increased and the shear torque of the serration increases. Therefore, it is possible to provide a wheel bearing device in which the slip torque of the hub bolt is increased and stabilized in combination with the suppression of the shape collapse and the reliability is improved.

  In the invention according to claim 2, since the wheel mounting flange is formed by dividing a portion excluding the vicinity of the bolt insertion hole into a plurality of partial flanges separated in the circumferential direction. The hub wheel can be reduced in size and weight, and when the wheel mounting flange is integrally formed with the inner member, the wheel mounting flange is not obstructed when the outer member is fastened to the knuckle. The knuckle bolt can be easily fastened with a tool, and the assembling work can be simplified.

  Preferably, as in the invention described in claim 3, the wheel mounting flange divided into the plurality of partial flanges is formed by notching a portion excluding the vicinity of the hub bolt insertion hole, and forming the bolt insertion hole. If the rib is formed so that the side surface on the inboard side of the wheel mounting flange gradually becomes thicker toward the base portion, with the substantially same width and protruding radially from the annular base portion, The hub ring is further thinned while ensuring the strength and durability of the hub wheel, and the size and weight can be reduced as much as possible.

  According to a fourth aspect of the present invention, since the serration is formed to be substantially flat by removing a predetermined amount of the outer diameter tip by rolling after rolling, variation in the outer diameter of the serration is prevented. The slip torque can be further stabilized.

  According to a fifth aspect of the present invention, the outer member integrally has a vehicle body mounting flange attached to a knuckle constituting a suspension device on the outer periphery, and a bolt insertion hole is formed in the outer peripheral portion. The vehicle body mounting flange has an R-shaped notch deeply formed between the bolt insertion holes, avoiding the periphery of the bolt insertion holes, from the pitch circle diameter of the bolt insertion holes to the inner diameter side. The weight can be reduced without impairing the rigidity of the device, and the device can be significantly reduced in size and weight in combination with the weight reduction of the hub wheel.

  The wheel bearing device according to the present invention includes an outer member having a double row outer raceway formed on the inner periphery, and a double row inner raceway facing the outer row raceway on the outer periphery. An inner member formed, and a double row rolling element that is rotatably accommodated between the rolling surfaces of the inner member and the outer member, the inner member or the outer member In the wheel bearing device in which a wheel mounting flange is integrally provided on either one, a bolt insertion hole is drilled in the wheel mounting flange, and a hub bolt with a serration formed in the neck is press-fitted into the bolt insertion hole. Since the cross-sectional shape of the tooth surface of the serration is formed in a substantially trapezoidal shape having a substantially flat portion on the outer diameter, the tooth surface of the serration is scraped off in the process of hub bolt press-fitting into the bolt insertion hole. To prevent crumble It is, tooth width even with the same press-fitting margin with the same number of teeth as the conventional substantially increases shear torque of serrations increases. Therefore, it is possible to provide a wheel bearing device in which the slip torque of the hub bolt is increased and stabilized in combination with the suppression of the shape collapse and the reliability is improved.

  An outer member having a double row outer raceway formed on the inner circumference, and a wheel mounting flange at one end, and one inner raceway facing the double row outer raceway on the outer circumference. And a hub wheel formed with a small-diameter step portion extending in the axial direction from the inner rolling surface, and the other inner side which is press-fitted into the small-diameter step portion of the hub wheel and faces the outer rolling surface of the double row on the outer periphery. An inner member composed of an inner ring formed with a rolling surface, and a double row rolling element that is slidably accommodated between the both rolling surfaces, and the end of the small-diameter step is radially outward. The inner ring is axially fixed to the hub ring by a caulking portion formed by plastic deformation in the direction, and a bolt insertion hole is drilled in the wheel mounting flange to form a serration at the neck. In the wheel bearing device in which the hub bolt is press-fitted into the bolt insertion hole, the wheel mounting flange is provided. A plurality of partial flanges are formed by cutting out a portion excluding the vicinity of the bolt insertion hole and projecting radially from the annular base with substantially the same width as the formation portion of the bolt insertion hole. The ribs are formed so that the side surface on the board side gradually becomes thicker toward the base portion, and the cross-sectional shape of the tooth surface of the serration is formed in a substantially trapezoidal shape having a substantially flat portion on the outer diameter. .

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 a front view showing a hub bolt in FIG. 1, and (b) is a view of serration of (a). It is a cross-sectional view. In the following description, the side closer to the outer side of the vehicle when assembled to the vehicle is referred to as the outboard side (left side in the drawing), and the side closer to the center is referred to as the inboard side (right side in the drawing).

  This wheel bearing device is on the drive wheel side, and includes an inner member 1 and an outer member 2, double row rolling elements (balls) 3 accommodated between the inner member 1 and the outer member 2, 3 is provided. The inner member 1 includes a hub ring 4 and a separate inner ring 5 fitted on the hub ring 4. The hub wheel 4 is integrally provided with a wheel mounting flange 6 for mounting a wheel (not shown) at an end portion on the outboard side, and the wheel mounting flange 6 is fixed at a circumferentially equidistant position. The hub bolt 7 is planted. Further, on the outer periphery of the hub wheel 4, an inner rolling surface 4a and a cylindrical small-diameter step portion 4b extending in the axial direction from the inner rolling surface 4a are formed. The inner ring 5 having the inner raceway surface 5a formed on the outer periphery is press-fitted into the small-diameter step portion 4b, and the end portion of the small-diameter step portion 4b is plastically deformed outward in the radial direction. This prevents the inner ring 5 from coming off in the axial direction with respect to the hub ring 4. In this embodiment, by adopting such a self-retain structure, it is not necessary to manage the preload by tightening firmly with a nut or the like as in the prior art, so that the ease of incorporation into the vehicle is simplified. In addition, the preload amount can be maintained for a long time.

  The outer member 2 integrally has a vehicle body mounting flange 2b for mounting to the vehicle body (not shown) on the outer periphery, and faces the double row inner rolling surfaces 4a and 5a of the inner member 1 on the inner periphery. Double row outer rolling surfaces 2a, 2a are formed. And the double row rolling elements 3, 3 are accommodated between the respective rolling surfaces 4a, 2a and 5a, 2a, and the double row rolling elements 3, 3 are held by the cages 8, 8 so as to roll freely. ing. In addition, seals 9 and 9 are attached to both ends of the outer member 2 to prevent leakage of the lubricating grease sealed inside the bearing and to prevent rainwater or dust from entering the bearing. ing.

  Here, the wheel bearing device referred to as the third generation in which the inner raceway surface 4a is formed directly on the outer periphery of the hub wheel 4 is illustrated, but the wheel bearing device according to the present invention is not limited to such a structure. For example, although not shown, a first generation or second generation structure in which a pair of inner rings are press-fitted into a small diameter step portion of the hub ring may be used. The outer member 2 may be an outer ring rotating type in which a wheel mounting flange 6 is provided, or may be a driven wheel or a driving wheel. Furthermore, although the double row angular contact ball bearing which used the rolling elements 3 and 3 as a ball | bowl was illustrated here, it is not restricted to this, The double row tapered roller bearing which uses a tapered roller for a rolling element may be sufficient.

  The hub wheel 4 is made of medium carbon steel containing 0.40 to 0.80% by weight of carbon such as S53C, and the seal land where the outboard side seal 9 is in sliding contact with the inner rolling surface 4a on the outboard side. The surface hardness is set to a range of 58 to 64 HRC by induction hardening over the part and the small diameter step part 4b. The caulking portion 4c is an unquenched portion having a surface hardness of 25HRC or less after forging. As a result, the strength of the hub wheel 4 is improved, and the fretting wear of the fitting surface with the inner ring 5 is prevented to improve the durability of the hub wheel 4. In addition, the workability when plastically deforming the caulking portion 4c is improved, and the occurrence of cracks and the like during the processing is prevented, and the reliability of the quality is improved. The inner ring 5 is made of a high carbon chrome bearing steel such as SUJ2, and is hardened in the range of 58 to 64 HRC up to the core part by quenching.

  On the other hand, the outer member 2 is formed of medium carbon steel containing 0.40 to 0.80% by weight of carbon, such as S53C, like the hub wheel 4 described above, and the double row outer rolling surfaces 2a and 2a have high frequency. The surface hardness is hardened by quenching to a range of 58 to 64 HRC.

  The wheel mounting flange 6 of the hub wheel 4 is formed with a plurality of bolt insertion holes 6a into which hub bolts 7 are press-fitted at the circumferentially equidistant positions after forging, and the hub bolts 7 are press-fitted into the bolt insertion holes 6a. However, the hub bolt 7 is made of chromium molybdenum steel (JIS standard SCM435 series or the like), and as shown in FIG. 2A, a serration 7a is formed at the neck. The surface of the hub bolt 7 is hardened by heat treatment, and the surface hardness is set to at least 35 HRC in terms of mechanical strength. Therefore, the serration 7a bites into the bolt insertion hole 6a and is firmly fixed by the hardness difference (10 HRC or more) between the hub bolt 7 and the bolt insertion hole 6a (see FIG. 1).

  In the present embodiment, as shown in FIG. 2B, the cross-sectional shape of the tooth surface in the serration 7a is formed in a substantially trapezoidal shape having a substantially flat portion on the outer diameter. Thereby, it is possible to prevent the tooth surface of the serration 7a from being scraped off and the shape of the serration 7a from being deformed in the process in which the hub bolt 7 is press-fitted into the bolt insertion hole 6a. Further, even if the same number of teeth and the same press-fitting allowance are used, the tooth width A substantially increases, and the shear torque of the serration 7a increases. Therefore, it is possible to provide a wheel bearing device in which the slip torque of the hub bolt 7 is increased and stabilized in combination with the suppression of the shape collapse and the reliability is improved.

  FIG. 3 is a comparison test result of slip torques of a conventional hub bolt (comparative example) and a hub bolt (example) according to the present invention implemented by the present applicant. As can be seen from this graph, in the hub bolt 7 of the present embodiment, the slip torque is increased by approximately 50% compared to the conventional one. The serration 7a having such a trapezoidal tooth surface is formed by a rolling process in the same manner as in the prior art by means of a rolling tooth previously formed into a trapezoidal shape. You may make it form the trapezoid shape by removing the front-end | tip part by cutting processes, such as grinding, on the outer diameter of the serration which makes a shape. Thereby, the variation in the outer diameter of the serration 7a can be prevented, and the slip torque can be further stabilized.

  FIG. 4 is a longitudinal sectional view showing a second embodiment of the wheel bearing device according to the present invention, and FIG. 5 is a side view of FIG. In the present embodiment, the hub wheel and the outer member are thinned to reduce the weight, and the same components and parts as those in the above-described embodiment are denoted by the same reference numerals and detailed description thereof is omitted.

  The wheel bearing device is a wheel bearing device that rotatably supports a driven wheel, and includes an inner member 10 and an outer member 11, and a double row accommodated between the inner member 10 and the outer member 11. Rolling elements (balls) 3 and 3. Here, the inner member 10 refers to the hub ring 12 and the inner ring 5 press-fitted into the hub ring 12.

  The hub wheel 12 integrally has a wheel mounting flange 13 divided into a plurality (four) in the circumferential direction at an end on the outer board side of the outer periphery, and a hub bolt 7 for fastening the wheel is planted on the outer periphery. It is installed. The wheel mounting flange 13 is formed so as to protrude radially from the annular base portion with a width substantially the same as the formation portion of each bolt insertion hole 6a by cutting out a portion excluding the vicinity of the hub bolt insertion hole 6a. That is, the wheel mounting flange 13 is divided into a plurality of partial flanges 13a separated in the circumferential direction (see FIG. 5). Further, ribs 13b are formed on the side surface of the wheel mounting flange 13 on the inboard side so as to gradually increase in thickness toward the base. Thereby, weight reduction can be achieved without impairing the rigidity of the hub wheel 12.

  A cylindrical brake pilot portion 16 extending toward the outboard side is formed at the base portion of the wheel mounting flange 13 of the hub wheel 12 to guide the inner diameter surface of the brake rotor 17. Further, a wheel pilot portion 18 extending from the brake pilot portion 16 to the outboard side is formed. The wheel pilot portion 18 guides an inner diameter surface of a wheel hub 19 mounted on the brake rotor 17 so as to be slightly smaller in diameter than the brake pilot portion 16. And the notch is provided in the several places of the circumferential direction, and it is intermittently formed in the shape of a protrusion. Here, the intermittent wheel pilot portion 18 is formed between a plurality of partial flanges 13a (see FIG. 5). Thereby, weight reduction can be achieved without reducing the rigidity of the hub wheel 12.

  In the present embodiment, as shown in FIG. 5, the wheel mounting flange 13 is cut out at a portion other than the vicinity of the bolt insertion hole 6a, and has an annular shape with substantially the same width as the formation portion of each bolt insertion hole 6a. Although the example formed so as to protrude radially from the base is not limited to this, although not shown in the drawing, the pitch circle diameter of the bolt insertion hole is determined between the bolt insertion holes by avoiding the periphery of the bolt insertion hole. It may be a wheel mounting flange having a flower shape in which an R-shaped notch is deeply formed to the inner diameter side.

  The outer member 11 integrally has a vehicle body mounting flange 14 attached to a knuckle (not shown) constituting a suspension device on the outer periphery, and a bolt insertion hole 15 is formed in the outer periphery. The vehicle body mounting flange 14 is formed with an R-shaped notch 14b between the bolt insertion holes 15 so as to avoid the periphery of the bolt insertion holes 15 and deeper from the pitch circle diameter of the bolt insertion holes 15 to the inner diameter side. That is, the vehicle body mounting flange 14 is divided into a plurality of partial flanges 14a separated in the circumferential direction (see FIG. 5). Further, a cylindrical knuckle pilot portion 14c extending in the axial direction from the vehicle body mounting flange 14 is formed at an end portion on the inboard side of the outer member 11, and the knuckle is fitted to the outer diameter surface of the knuckle pilot portion 14c. Is done.

  A cup-shaped seal cap (not shown) is attached to the end of the outer member 11 on the inboard side, and closes the opening of the outer member 11. The seal cap and the seal 9 on the outboard side prevent the lubricating grease sealed inside the bearing from leaking to the outside and preventing rainwater, dust, etc. from entering the bearing from the outside.

  In the present embodiment, the wheel mounting flange 13 of the hub wheel 12 is cut out at a portion other than the vicinity of the bolt insertion hole 6a, and only the portion where each bolt insertion hole 6a is formed has substantially the same width from the annular base to the outer diameter side. Since it is formed so as to protrude, the knuckle bolt can be easily fastened with a tool without being obstructed by the wheel mounting flange 13 when the outer member 11 is fastened to the knuckle. Work can be simplified.

  In addition, the hub wheel 12 and the outer member 11 are significantly thinned, and the wheel mounting flange 13 and the vehicle body mounting flange 14 are formed by being divided into four partial flanges 13a and 14a, which are completely different from conventional disk-shaped flanges. Therefore, it is possible to reduce the weight and size of the apparatus while ensuring the strength and durability.

  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 is applied to any wheel bearing device of a drive wheel, a driven wheel, or an inner ring rotating type or an outer ring rotating type having a wheel mounting flange into which a hub bolt for mounting a wheel is press-fitted. Can do.

It is a longitudinal section showing a 1st embodiment of a bearing device for wheels concerning the present invention. (A) is a front view which shows a hub bolt same as the above. (B) is a cross-sectional view showing the tooth surface of the serration of (a). It is a graph which shows the test result which compared the slip torque of the hub bolt concerning this invention, and the conventional hub bolt. It is a longitudinal cross-sectional view which shows 2nd Embodiment of the wheel bearing apparatus which concerns on this invention. It is a side view same as the above. It is a longitudinal cross-sectional view which shows the conventional wheel bearing apparatus. (A) is the principal part enlarged view same as the above. (B) is a cross-sectional view showing the tooth surface of the serration of (a).

Explanation of symbols

1, 10 ... inner member 2,11 ... outer member 2a ...・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Rolling surface 3 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Rolling elements 4, 12 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Hub wheel 4a, 5a ············ Inner rolling surface 4b ·············· Small diameter step 4c ······· ··································· 5 15 Bolt insertion hole 7 Hub bolt 7a ...・ ・ ・ ・ Serration 8 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Retainer 9 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Sea 13a, 14a ... Partial flange 13b ... Rib 14 ... Car body mounting flange 14b ... Notch part 14c ... Knuckle pilot part 16 ... ... Brake pilot part 17 ... Brake rotor 18 ... Wheel pilot part 19 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Wheel hub 50 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Suspension device 51 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・... Outer member 51a ... Outer rolling surface 51b ... Vehicle mounting flange 52 ... ... ... Wheel mounting flange 53 ... Hub wheels 53a, 54a ... Inside rolling surface 53b ... ········· Small diameter step 54 ·········································· 56 ... Rolling element 57 ... Hub bolt 58 ... .... Bolt insertion hole 59 ..... Front side serration 60 ..... Rear side serration A ..・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Tooth width

Claims (5)

An outer member having a double row outer raceway 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 housed movably between the rolling surfaces of the inner member and the outer member;
A wheel mounting flange is integrally provided on either the inner member or the outer member, and a bolt insertion hole is drilled in the wheel mounting flange, and a hub bolt with a serration formed in the neck is formed in the bolt insertion hole. In the press-fitted wheel bearing device,
The wheel bearing device according to claim 1, wherein a cross-sectional shape of the tooth surface of the serration is formed in a substantially trapezoidal shape having a substantially flat portion on an outer diameter.   2. The wheel bearing device according to claim 1, wherein the wheel mounting flange is formed by dividing a portion excluding the vicinity of the bolt insertion hole into a plurality of partial flanges separated in the circumferential direction.   The wheel mounting flange divided into the plurality of partial flanges has a width substantially the same as that of the bolt insertion hole and protrudes radially from the annular base portion. The wheel bearing device according to claim 2, wherein the rib is formed so that the side surface gradually becomes thicker toward the base portion.   The wheel bearing device according to any one of claims 1 to 3, wherein the serration is formed to be substantially flat after a predetermined amount is removed by a cutting process after rolling.   The outer member integrally has a vehicle body mounting flange attached to a knuckle constituting a suspension device on the outer periphery, and a bolt insertion hole is formed in the outer peripheral portion, and the vehicle body mounting flange is connected to the bolt insertion hole. 5. The wheel bearing device according to claim 1, wherein an R-shaped notch is formed between the bolt insertion holes so as to avoid the periphery of the bolt and deeper from the pitch circle diameter of the bolt insertion holes to the inner diameter side.

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