Hub unit bearing and method of manufacturing the same

Abstract

To provide a hub unit bearing capable of ensuring a wide area of an outboard side surface of a vehicle body attaching flange while maintaining strength due to forging without cutting a part on an outboard side of an outer ring.SOLUTION: A hub unit bearing is equipped with an outer ring 20 that has a vehicle body attaching flange 24, a hub 30 that has a wheel attaching flange 33, and a plurality of rolling bodies 40 provided between outer ring raceways 21a and 21b and inner ring raceways 35a and 35b. On an outboard side of an outer peripheral surface 24d of the vehicle body attaching flange 24, a flush trace 27a is formed.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a hub unit bearing that rotatably supports an automobile wheel relative to a suspension system. [Background technology]

[0002] Conventionally, the outer ring of a hub unit bearing formed by forging is fastened to the knuckle by tightening a bolt from the inboard side of the knuckle if the insertion hole for inserting the knuckle bolt is a female thread, or is fastened to the knuckle by tightening a bolt from the outboard side if the insertion hole is a cylindrical hole.

[0003] For example, in the case of a wheel bearing device 100 described in Patent Document 1 shown in Figure 6, a hub ring 101 has a wheel mounting flange 102 extending radially outward from a cylindrical portion, and a wheel 105 and the hub ring 101 are fixed together by hub bolts 103 inserted into flange locking holes 104. Furthermore, an outer ring 111 has a vehicle body mounting flange 114 extending radially outward from the outer periphery of a cylindrical portion 112, and a knuckle 117 is fastened to the outer ring 111 by a knuckle bolt 115 inserted into a flange locking hole 116, which is a cylindrical hole.

[0004] Patent Document 2 also describes that the outer ring for a rolling bearing unit is forged so that a highly clean metal material is exposed in the double-row outer ring raceway, thereby improving the rolling fatigue life of the outer ring raceway. Patent Document 2 also describes that by forging so that flash appears on the outer peripheral surface of the inboard side of the flange, the deformation resistance of the inboard side part of the flange during forging is reduced, the radius of curvature of the corner R part on the inboard side is reduced, and the amount of removal in finish cutting is reduced. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2020-85205 [Patent Document 2] Japanese Patent Application Laid-Open No. 2015-107495 Summary of the Invention [Problem to be solved by the invention]

[0006] As described in Patent Document 1, when the vehicle body mounting flange 114 is fixed to the knuckle 117 with the knuckle bolt 115, the vehicle body mounting flange 114 needs to have a seating surface on the outboard side surface 120 on which the head 115a of the knuckle bolt 115 can seat. In addition, when a fastening tool such as a socket is placed on the head 115a of the knuckle bolt 115, it is necessary to prevent the fastening tool from interfering with the surrounding area, such as the outer peripheral surface of the cylindrical portion 112. Therefore, to satisfy the above requirements without increasing the size of the vehicle body mounting flange 114, it is desirable to reduce the outer diameter of the cylindrical portion 112 on the outboard side of the outer ring 111 and the radius of curvature of the corner R portion 121 between the outer peripheral surface of the cylindrical portion 112 and the outboard side surface 120 of the vehicle body mounting flange 114.

[0007] However, if cutting is performed on the outer peripheral surface of cylindrical portion 112 to reduce the outer diameter of outboard side cylindrical portion 112 of outer ring 111, there is a concern that the grain flows will be cut and the strength of outboard side corner R portion 121 will be reduced. Since a large load is applied from knuckle 117 to corner R portion 121 on the outboard side of vehicle body mounting flange 114, strength is required.

[0008] The present invention has been made in consideration of the above-mentioned problems, and its object is to provide a hub unit bearing that can ensure a large area on the outboard side surface of the vehicle body mounting flange while maintaining the strength achieved by forging, without having to perform cutting on the cylindrical portion on the outboard side of the outer ring. [Means for solving the problem]

[0009] The above object of the present invention can be achieved by the following configuration. [1] An outer ring having a cylindrical portion having an outer ring raceway on its inner peripheral surface, and a vehicle body mounting flange extending radially outward from the periphery of the cylindrical portion and having a plurality of insertion holes for inserting knuckle bolts; a hub having an inner ring raceway on its outer peripheral surface at a position opposite the outer ring raceway, and having a wheel mounting flange extending radially outward from a portion located outboard of the outer ring; a plurality of rolling elements provided between the outer ring raceway and the inner ring raceway so as to be able to roll freely; A hub unit bearing comprising: A hub unit bearing in which a flash mark is formed on the outer peripheral surface on the outboard side of the vehicle body mounting flange. [Effects of the Invention]

[0010] According to the hub unit bearing of the present invention, it is possible to ensure a large area on the outboard side surface of the vehicle body mounting flange while maintaining the strength achieved by forging, without having to perform cutting work on the cylindrical portion on the outboard side of the outer ring. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a vertical cross-sectional view of a hub unit bearing according to an embodiment of the present invention. [Figure 2] FIG. 2 is a left side view (viewed from the outboard side) of the outer ring shown in FIG. 1. [Figure 3] FIG. 3 is a cross-sectional view taken along the line III-III in FIG. 2. [Figure 4] FIG. 10 is a left side view (viewed from the outboard side) of the outer ring of a modified example. [Figure 5] FIG. 5 is a cross-sectional view of FIG. 4 . [Figure 6] FIG. 10 is a vertical cross-sectional view of a conventional hub unit bearing. DETAILED DESCRIPTION OF THE INVENTION

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a hub unit bearing according to the present invention will now be described in detail with reference to the drawings. In addition, throughout this specification and the claims, the "outboard side" in the axial direction refers to the left side in Figure 1, which is the outer side in the width direction of the vehicle body when assembled to the automobile, and conversely, the right side in Figure 1, which is the center side in the width direction of the vehicle body, is referred to as the "inboard side" in the axial direction.

[0013] As shown in FIG. 1, a hub unit bearing 10 according to this embodiment is for a driven wheel, and includes an outer ring 20, a hub 30, a plurality of rolling elements 40, a seal ring 50, and a cap 60.

[0014] The outer ring 20 comprises a cylindrical portion 22 having double-row outer ring raceways 21a, 21b on its inner peripheral surface, a circumferential flange 23 formed around the entire outer periphery in the axially middle portion of the cylindrical portion 22, and four vehicle body mounting flanges 24 extending radially outward from circumferentially spaced positions of the circumferential flange 23. The number of vehicle body mounting flanges 24 is not limited to four and may be, for example, three.

[0015] The vehicle body mounting flanges 24 are each formed with an insertion hole 26 for inserting a knuckle bolt 25. When in use, the vehicle body mounting flanges 24 are connected and fixed to the knuckle 11 of the suspension system via the knuckle bolts 25, so that the outer ring 20 is supported by the knuckle 11 and does not rotate.

[0016] The hub 30 is configured by joining a hub ring 31 and an inner ring 32 together, and is disposed coaxially (concentrically) with the outer ring 20 on the inner diameter side of the outer ring 20 .

[0017] The hub wheel 31 is provided with a circular wheel mounting flange 33 that extends radially outward at a portion located further outboard (on the left side in Figure 1) than the outboard end of the outer ring 20, for supporting and fixing a wheel (driven wheel) and a braking rotating member such as a disc rotor.

[0018] A stud bolt (not shown) is serrated-fitted into each insertion hole 34 provided in the wheel mounting flange 33 to fix a wheel (driven wheel) and a braking rotating member (not shown), such as a disc rotor. The wheel mounting flange 33 also has a work hole 38 at a position corresponding to the insertion hole 26 of the vehicle body mounting flange 24, into which a fastening tool (for example, a socket) for fastening the knuckle bolt 25 can be inserted.

[0019] An outboard-side inner ring raceway 35a is provided on the outer peripheral surface of the hub ring 31 at a portion facing the outboard-side outer ring raceway 21a provided on the inner peripheral surface of the outer ring 20. A small diameter step 36 is provided on the outer peripheral surface of the hub ring 31 at an inboard end portion facing the inboard-side outer ring raceway 21b provided on the inner peripheral surface of the outer ring 20.

[0020] An inboard inner ring raceway 35b is provided on the outer peripheral surface of the inner ring 32, and the inner ring 32 is externally fitted and fixed to the small diameter step portion 36 of the hub ring 31 by an interference fit, and is positioned and fixed in the axial direction by a crimping portion 37 formed by crimping the inboard end portion of the hub ring 31 radially outward.

[0021] Furthermore, the pitch circle diameter PCD1 of the plurality of working holes 38 and the pitch circle diameter PCD2 of the plurality of insertion holes 26 are the same size, and furthermore, the diameter D3 of the inscribed circle of the plurality of working holes 38 is equal to or greater than the diameter D1 of the outer peripheral surface of the outboard-side cylindrical portion 22A. This allows a fastening tool for fastening the knuckle bolt 25 to be easily inserted into the working hole 38 without interfering with the cylindrical portion 22, improving operability.

[0022] The rolling elements 40 are arranged so that they can roll freely while being held by a retainer 41, with multiple rolling elements 40 located between the outer ring raceway 21a and the inner ring raceway 35a on the outboard side, and between the outer ring raceway 21b and the inner ring raceway 35b on the inboard side. In the illustrated example, balls are used as the rolling elements 40, but in the case of a rolling bearing unit for supporting the wheels of an automobile, which is heavy, tapered rollers may be used instead of balls.

[0023] The seal ring 50 is supported and fixed to the outboard end of the outer ring 20, and blocks the opening at the outboard end of the internal space 42, which is located between the inner surface of the outer ring 20 and the outer surface of the hub 30 and in which multiple rolling elements 40 are provided.

[0024] On the other hand, the cap 60 is configured in a cylindrical shape with a bottom, and when assembled to the inboard end of the outer ring 20 , closes the opening at the inboard end of the outer ring 20 .

[0025] The encoder 12 is fitted and fixed to the inboard end of the inner ring 32 of the hub 30, and a sensor unit (not shown) is attached to the holding portion 61 of the cap 60. The detection portion of the sensor unit is positioned closely opposite the detection surface of the encoder 12, making it possible to measure the rotational speed and other parameters of the hub 30. The structure of the sensor unit is not relevant to the gist of the present invention, so a detailed description will be omitted.

[0026] Referring also to Figures 2 and 3, the cylindrical portion 22 of the outer ring 20 has an outboard side cylindrical portion 22A formed on the outboard side of the vehicle body mounting flange 24, and an inboard side cylindrical portion 22B formed on the inboard side of the vehicle body mounting flange 24.

[0027] The diameter D1 of the outer peripheral surface of the outboard side cylindrical portion 22A is smaller than the diameter D2 of the outer peripheral surface of the inboard side cylindrical portion 22B. Furthermore, the radius of curvature of the corner R portion 28a, which has an arc-shaped cross section and where the outboard side surface 24a of the vehicle body mounting flange 24 and the outer peripheral surface of the outboard side cylindrical portion 22A intersect, is made smaller, thereby increasing the area of ​​the outboard side surface 24a of the vehicle body mounting flange 24.

[0028] This ensures that the outboard side surface 24a of the vehicle body mounting flange 24 has a sufficient seating surface on which the head 25a of the knuckle bolt 25 for connecting and fixing the outer ring 20 to the knuckle 11 can be seated (see FIG. 1). Furthermore, when a fastening tool, such as a socket, is set to fasten the knuckle bolt 25, the fastening tool can be prevented from interfering with the outer peripheral surface of the outboard side cylindrical portion 22A.

[0029] Furthermore, the outer ring 20 formed in this manner is strong enough to withstand the load from the wheel, and is therefore formed by forging, as in Patent Document 2. In particular, in the forming process of the outer ring 20, a billet after upsetting is subjected to semi-closed forging to form the circumferential flange 23 and the vehicle body mounting flange 24, and in this embodiment, flash 27, which is excess material shown by phantom lines in Figures 2 and 3, is formed on the outboard sides of the outer peripheral surfaces 23d, 24d of the circumferential flange 23 and the vehicle body mounting flange 24. The flash 27 is removed by trimming, and therefore flash marks 27a are formed on the outer ring 20 on the outboard sides of the outer peripheral surfaces 23d, 24d of the circumferential flange 23 and the vehicle body mounting flange 24.

[0030] That is, by forming a flash 27 on the outboard side of the outer peripheral surfaces 23d, 24d of the circumferential flange 23 and the vehicle body mounting flange 24, the fluidity of the material on the outboard side is increased during forging, the radius of curvature of the corner R portion 28a where the outboard side surface 24a of the vehicle body mounting flange 24 intersects with the outer peripheral surface of the outboard side cylindrical portion 22A is reduced, and the area of ​​the outboard side surface 24a of the vehicle body mounting flange 24 is increased.

[0031] This makes it possible to ensure a large area for the outboard side surface 24a of the vehicle body mounting flange 24 without cutting the outboard side surface 24a of the vehicle body mounting flange 24 or the outer peripheral surface of the outboard side cylindrical portion 22A; in other words, without cutting the outboard side grain flows and reducing the strength of the vehicle body mounting flange 24.

[0032] On the other hand, by increasing the fluidity on the outboard side, the fluidity on the inboard side may decrease slightly, which may increase the radius of curvature of the corner R portion 28b where the inboard side surface 24b of the vehicle body mounting flange 24 intersects with the outer peripheral surface of the inboard side cylindrical portion 22B.

[0033] However, even if the radius of curvature is reduced by cutting corner R portion 28b and the grain flows at corner R portion 28b are cut, this does not result in a reduction in strength because the outer peripheral surface of inboard cylindrical portion 22B is fitted into knuckle 11. Furthermore, diameter D2 of the outer peripheral surface of inboard cylindrical portion 22B is larger than diameter D1 of the outer peripheral surface of outboard cylindrical portion 22A, i.e., the wall thickness of inboard cylindrical portion 22B is thicker than the wall thickness of outboard cylindrical portion 22A, so the strength of inboard cylindrical portion 22B is ensured.

[0034] As described above, with the hub unit bearing 10 of this embodiment, it is possible to ensure a large area for the outboard side surface 24a of the vehicle body mounting flange 24 while maintaining the strength achieved by forging, without performing cutting work on the outboard side cylindrical portion 22A of the outer ring 20.

[0035] Next, an outer ring of a hub unit bearing according to a modified example of this embodiment will be described with reference to FIGS.

[0036] 4 and 5, the outer ring 20 of this modified example is also formed, as described above, using two divided semi-hermetic forging dies (not shown, but see, for example, Figure 3 of JP 2015-107459 A (Patent Document 2)) at positions on the outboard side of the circumferential flange 23 and the vehicle body mounting flange 24. For this reason, the outer peripheral surfaces 23d, 24d of the circumferential flange 23 and the vehicle body mounting flange 24 form inclined surfaces 23c, 24c whose diameters gradually decrease toward the inboard side, which is a draft angle.

[0037] When the outer ring 20, whose outer peripheral surfaces 23d, 24d are inclined surfaces 23c, 24c, is fixed to the knuckle 11 by the vehicle body mounting flange 24, an arc-shaped recess 39 (FIG. 5) with a V-shaped cross section in the axial direction is formed, with the bottom being the arc-shaped abutting edge portion between the inboard edge 23e of the upper circumferential flange 23 (FIG. 4) and the knuckle 11.

[0038] In particular, when there are four vehicle body mounting flanges 24, both circumferential sides of this recess 39 are closed by two of the vehicle body mounting flanges 24, so water that adheres to the inclined surface 23c (outer peripheral surface 23d), which is the upper surface of the circumferential flange 23, flows inboard along the inclined surface 23c and accumulates in the recess 39, forming a pool. Water that accumulates in the recess 39 may cause rust in the hub unit bearing 10 and the knuckle 11.

[0039] For this reason, the outer ring 20 of this modified example has drainage grooves 29 on both circumferential sides of the inclined surface 23c. The drainage grooves 29 gradually decrease in diameter from the inboard edge 23e of the upper circumferential flange 23, or from a position smaller in diameter than the edge 23e, toward the outboard side. The drainage grooves 29 are preferably provided at positions facing each other on the circumferential inner sides of the two upper, circumferentially adjacent vehicle body mounting flanges 24, i.e., at the lowest positions of the depressions 39 that tend to pool. This allows most of the water that flows inboard along the inclined surface 23c (outer peripheral surface 23d) to be drained, eliminating the possibility of rusting of the hub unit bearing 10 and the knuckle 11. The shape of the drainage grooves 29 is arbitrary, and although they may be formed by cutting, they are preferably formed by additional forging.

[0040] Other parts than those described above are the same as those of the hub unit bearing of the first embodiment, and therefore description thereof will be omitted.

[0041] The present invention is not limited to the above-described embodiment and modifications, and can be modified, improved, etc. as appropriate. For example, in the above embodiment, the vehicle body mounting flange extends radially outward from the entire circumferential flange, but the present invention is not limited to this, and the vehicle body mounting flange may extend radially outward from the periphery of the cylindrical portion. Furthermore, the hub of the present invention is not limited to that of the above embodiment, but may be configured with a hub axle and a pair of inner rings.

[0042] As described above, the present specification discloses the following: (1) An outer ring having a cylindrical portion having an outer ring raceway on its inner peripheral surface, and a vehicle body mounting flange extending radially outward from the periphery of the cylindrical portion and having a plurality of insertion holes for inserting knuckle bolts; a hub having an inner ring raceway on its outer peripheral surface at a position opposite the outer ring raceway, and having a wheel mounting flange extending radially outward from a portion located outboard of the outer ring; a plurality of rolling elements provided between the outer ring raceway and the inner ring raceway so as to be able to roll freely; A hub unit bearing comprising: A flash mark is formed on the outer peripheral surface of the outboard side of the vehicle body mounting flange. Hub unit bearing. With this configuration, it is possible to ensure a large area on the outboard side of the vehicle body mounting flange while maintaining the strength achieved by forging, without having to perform cutting work on the cylindrical portion on the outboard side of the outer ring.

[0043] (2) The cylindrical portion of the outer ring is formed so that the diameter of the outer peripheral surface on the outboard side relative to the vehicle body mounting flange is smaller than the diameter of the outer peripheral surface on the inboard side relative to the vehicle body mounting flange. The hub unit bearing according to (1). With this configuration, not only can a large area be secured on the outboard side surface of the vehicle body mounting flange, but the wall thickness of the cylindrical portion on the inboard side can also be increased.

[0044] (3) The wheel mounting flange has a plurality of work holes into which a fastening tool for fastening the knuckle bolt can be inserted, the pitch circle diameters of the plurality of work holes and the pitch circle diameters of the plurality of insertion holes are the same, and the diameters of the inscribed circles of the plurality of work holes are equal to or greater than the diameter of the outer circumferential surface of the cylindrical portion on the outboard side. The hub unit bearing according to (1) or (2). According to this configuration, a fastening tool for fastening the knuckle bolt can be easily inserted through the work hole in the wheel mounting flange, improving workability.

[0045] (4) The outer ring includes a plurality of vehicle body mounting flanges extending radially outward from a periphery of a circumferential flange formed around the entire outer periphery of the cylindrical portion, The outer peripheral surface of the circumferential flange provided between the circumferentially adjacent vehicle body mounting flanges at the upper part includes an inclined surface that slopes so that the diameter gradually decreases toward the inboard side, and a drainage groove that gradually decreases in diameter from the edge of the circumferential flange on the inboard side or from a position with a diameter smaller than the edge toward the outboard side. The hub unit bearing according to any one of (1) to (3). With this configuration, water that flows inboard from the inclined surface that is formed on the outer peripheral surface of the full-circumference flange located above and that slopes toward the inboard side can be discharged to the outboard side, preventing the occurrence of rust on the hub unit bearing and knuckle. [Explanation of symbols]

[0046] 10 Hub unit bearing 20 outer ring 21a, 21b outer raceway 22A Outboard cylindrical part (cylindrical part of outer ring) 22B Inboard cylindrical part (cylindrical part of outer ring) 23 All-around flange 23c Slope 23d Outer surface of full flange 23e Edge 24 Body mounting flange 24d Outer surface of vehicle body mounting flange 25 Knuckle Bolt 26 Insertion hole 27 Flash 27a Flash marks 29 Drainage groove 30 Hub 33 Wheel mounting flange 35a, 35b inner raceway 38 Working hole 40 rolling elements D1 Outboard cylindrical diameter D2 Inboard cylindrical diameter D3 Diameter of the inscribed circle of the work hole PCD1, PCD2 pitch circle diameter

Claims

1. an outer ring having a cylindrical portion having an outer ring raceway on its inner peripheral surface, and a vehicle body mounting flange extending radially outward from the periphery of the cylindrical portion and having a plurality of insertion holes for inserting knuckle bolts; a hub having an inner ring raceway on its outer peripheral surface at a position opposite the outer ring raceway, and having a wheel mounting flange extending radially outward from a portion located outboard of the outer ring; a plurality of rolling elements provided between the outer ring raceway and the inner ring raceway so as to be able to roll freely; A hub unit bearing comprising: a flash mark is formed on the outer peripheral surface of the outboard side of the vehicle body mounting flange, The outer peripheral surface of the vehicle body mounting flange is an inclined surface whose diameter gradually decreases toward the inboard side. Hub unit bearing.

2. the cylindrical portion of the outer ring is formed so that the diameter of the outer peripheral surface on the outboard side relative to the vehicle body mounting flange is smaller than the diameter of the outer peripheral surface on the inboard side relative to the vehicle body mounting flange. The hub unit bearing according to claim 1 .

3. the wheel mounting flange has a plurality of work holes into which a fastening tool for fastening the knuckle bolt can be inserted, the pitch circle diameters of the plurality of work holes and the pitch circle diameters of the plurality of insertion holes are the same, and the diameters of the inscribed circles of the plurality of work holes are equal to or greater than the diameter of the outer circumferential surface of the cylindrical portion on the outboard side. The hub unit bearing according to claim 1 or 2.

4. The outer ring has a plurality of vehicle body mounting flanges extending radially outward from a periphery of a circumferential flange formed around the entire outer periphery of the cylindrical portion, an outer circumferential surface of the full circumferential flange provided between the upper and circumferentially adjacent vehicle body mounting flanges includes an inclined surface that gradually decreases in diameter toward the inboard side; The hub unit bearing according to any one of claims 1 to 3.

5. the outer ring includes a plurality of vehicle body mounting flanges extending radially outward from the periphery of the entire circumferential flange formed around the entire outer periphery of the cylindrical portion, The outer peripheral surface of the circumferential flange provided between the circumferentially adjacent vehicle body mounting flanges at the upper part includes the inclined surface that slopes so that the diameter gradually decreases toward the inboard side, and a drainage groove that gradually decreases in diameter from the edge of the circumferential flange on the inboard side or from a position with a diameter smaller than the edge toward the outboard side. The hub unit bearing according to claim 4.

6. An outer ring having a cylindrical portion having an outer ring raceway on its inner peripheral surface, and a vehicle body mounting flange extending radially outward from the periphery of the cylindrical portion and having a plurality of insertion holes for inserting knuckle bolts; a hub having an inner ring raceway on its outer peripheral surface at a position opposite the outer ring raceway, and having a wheel mounting flange extending radially outward from a portion located outboard of the outer ring; a plurality of rolling elements provided between the outer ring raceway and the inner ring raceway so as to be able to roll freely; A manufacturing method of a hub unit bearing comprising: a step of semi-closed forging the outer ring so that a flash is formed on the outer peripheral surface of the outboard side of the vehicle body mounting flange, and the outer peripheral surface of the vehicle body mounting flange has an inclined surface whose diameter gradually decreases toward the inboard side; removing the flash so that a flash mark is formed on an outer peripheral surface of the outboard side of the vehicle body mounting flange; A method for manufacturing a hub unit bearing comprising:

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