Hub unit bearing

Abstract

To provide a hub unit bearing with a cap high in fitting force and water tightness.SOLUTION: The cap has a synthetic resin cap body containing filler, and a metal core grid fixed to the cap body. The cap body, wholly bottomed cylindrical, has an approximately disc shaped resin bottom plate part, and an approximately cylindrical resin cylinder part extending from the radial outside of the resin bottom plate part to the outboard side. The wholly annular core grid is L-shaped in cross section, having an approximately cylindrical core grid cylinder part extending in the axial direction, and a core grid flange part extending from the inboard side end of the core grid cylinder part to the radial outside. The resin cylinder part has a large diameter portion covering the core grid flange part from the radial outside, and a small diameter portion covering the core grid cylinder part from the radial outside. The small diameter portion of the resin cylinder part is internally fitted to the inboard side end of an outer ring. The filler content of the small diameter portion of the resin cylinder part is smaller than the filler content of the resin bottom plate part.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a hub unit bearing used for rotatably supporting a wheel of an automobile with respect to a suspension device.

Background Art

[0002] A hub unit bearing that rotatably supports a wheel (driven wheel) of an automobile with respect to a suspension device and combines a rotational speed detection device for detecting the rotational speed of the wheel necessary for control such as ABS has been widely used conventionally.

[0003] For example, Patent Document 1 discloses an outer ring having an outer ring raceway on its inner peripheral surface and not rotating even during use, a hub having an inner ring raceway on its outer peripheral surface and rotating during use, a plurality of rolling elements provided between these outer ring raceway and inner ring raceway so as to be freely rollable, an encoder supported and fixed concentrically with the hub at the inner end portion in the axial direction of the hub, and having its characteristics changed alternately and at equal pitch in the circumferential direction, and a bearing cap attached to the inner end portion in the axial direction of the outer ring in a state of closing the inner end opening in the axial direction of the outer ring, and having a sensor holder supported and fixed to a part thereof. The bearing cap has a cap body made of synthetic resin and having a bottomed cylindrical shape, and a metal ring (core metal) mold-fixed to the cap body. [[ID=??]]

[0004] Further, in the hub unit bearing described in Patent Document 2, the resin end cap (including the sensor holder) made of a core metal and resin is not in a close contact state between the core metal and the resin, and a gap is formed between the resin on the inner diameter side of the core metal and the core metal due to molding shrinkage, so that external muddy water may enter the hub unit bearing along the core metal.

[0005] It seems there is a typo in ID 18 where it should probably be something like "ID=18" instead of "

[0004] " in the original text. I've translated it as best as possible with the given content.To address these problems, the bearing cap described in Patent Document 1 uses an O-ring as a sealing material. Furthermore, in the bearing cap described in Patent Document 2, the surfaces of the core metal member and the resin member that face each other at the joint portion are bonded together without gaps by an adhesive layer. However, both methods described in Patent Documents 1 and 2 lead to increased costs.

[0006] Therefore, as disclosed in Patent Document 3, a method can be considered in which the mating surface of the bearing cap to the outer ring is made of resin, and the mating portion is made watertight by the elasticity of the resin. However, it is known that many resins absorb water and swell with water, and in particular, polyamides used in resin caps are known to be highly hydrophilic because they have an amide group (chemical formula: CONH2) in their molecule.

[0007] To prevent dimensional changes due to water absorption, especially in the large-volume bottom plate portion of the resin cap, a material is usually selected that contains 30% or more (but less than 50%) of reinforcing filler such as fiberglass (GF) to suppress water absorption. However, because this material is hard, axial scratches are easily formed on the resin cap when it is pressed into the outer ring, and it lacks the flexibility to be used as a sealing material to obtain a watertight seal on the mating surface, making it prone to water ingress from the mating surface. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2016-148387 [Patent Document 2] Japanese Patent Publication No. 2011-174511 [Patent Document 3] Japanese Patent Publication No. 2011-052755 [Overview of the project] [Problems that the invention aims to solve]

[0009] This invention has been made in view of the circumstances described above, and aims to provide a hub unit bearing with high cap fitting force and watertightness. [Means for solving the problem]

[0010] The above objective of the present invention is achieved by the following configuration. (1) An outer ring having a double row of outer ring raceway surfaces formed on its inner circumference, An inner ring having a double row of inner ring raceway surfaces formed on its outer surface, A plurality of rolling elements are arranged to roll freely between the double-row inner ring raceway surface and the double-row outer ring raceway surface, A cap is fixed to the inboard-side end of the outer ring and closes the opening on the inboard side of the outer ring, A hub unit bearing equipped with, The aforementioned cap comprises a cap body made of synthetic resin containing a filler, and a metal core fixed to the cap body. The cap body is a bottomed cylindrical shape overall, and has a substantially disc-shaped resin bottom plate portion and a substantially cylindrical resin tube portion extending from the radially outer portion of the resin bottom plate portion toward the outboard side. The core metal is annular in shape and has an L-shaped cross-section, comprising a substantially cylindrical core metal tube portion extending in the axial direction and a core metal flange portion extending radially outward from the inboard side end of the core metal tube portion. The resin cylinder portion has a large-diameter portion that covers the core metal flange portion from the radially outer side, and a small-diameter portion that covers the core metal cylinder portion from the radially outer side, The small diameter portion of the resin cylinder is fitted inside the inboard end of the outer ring. The content of the filler in the small diameter portion of the resin cylinder is smaller than the content of the filler in the resin bottom plate portion. Hub unit bearing. (2) The content of the filler in the small diameter portion of the resin cylinder changes in the circumferential direction. (1) The hub unit bearing described above. (3) Notches are provided at multiple locations in the circumferential direction of the radial outer end of the core metal flange portion. The hub unit bearing according to (2). (4) A plurality of through holes are provided at a plurality of circumferential positions at the root of the core metal flange portion. The hub unit bearing according to (2). [Advantages of the Invention]

[0011] According to the hub unit bearing of the present invention, a hub unit bearing with high fitting force and watertightness of the cap is provided. [Brief Description of the Drawings] <00神仙道0075>

[0012] 神仙道 [Figure 1] It is a cross-sectional view of the hub unit bearing according to the first embodiment. [Figure 2] It is an enlarged view of the main part of the hub unit bearing according to the first embodiment. [Figure 3] It is an enlarged view of the main part of the hub unit bearing according to the second embodiment. [Figure 4] It is an enlarged view of the main part of the hub unit bearing according to the third embodiment. [Modes for Carrying Out the Invention]

[0013] [First Embodiment] The hub unit bearing according to the first embodiment of the present invention will be described in detail with reference to FIGS. 1 to 2. FIG. 1 is a cross-sectional view of the hub unit bearing according to the first embodiment. FIG. 2 is an enlarged view of the main part of the hub unit bearing according to the first embodiment.

[0014] Regarding the hub unit bearing, throughout this specification and the claims, in the axial direction, "outer" refers to the left side in FIG. 1, which is the outer side in the vehicle body width direction in the assembled state to the vehicle, and is also referred to as the "outboard side". Conversely, the right side in FIG. 1, which is the center side in the vehicle body width direction, is referred to as "inner" in the axial direction and is also referred to as the "inboard side".

[0015] The hub unit bearing 1 of the present embodiment is for a driven wheel and mainly includes an outer ring 2, an inner ring 3, and a plurality of rolling elements 4, 4.

[0016] The outer ring 2 has a stationary flange 7 formed on its outer circumference and double-row (2-row) outer ring raceway surfaces 8a and 8b formed on its inner circumference. When in use, the outer ring 2 does not rotate while supported by the suspension device by connecting and fixing the stationary flange 7 to the knuckle of the suspension device.

[0017] The inner ring 3 is composed of a hub ring 9 and an inner ring member 10, and is arranged coaxially (concentrically) with the outer ring 2 on the radially inner side of the outer ring 2.

[0018] The hub ring 9 is provided with a circular rotating flange 11 that extends radially outward from the axially outward (outboard side) opening of the outer ring 2, for supporting and fixing the wheel (drive wheel) and braking rotating members such as the disc rotor. Specifically, the rotating flange 11 is provided with a plurality of through holes 11a, and hub bolts 17 are serrated into each through hole 11a. Alternatively, the plurality of through holes 11a of the rotating flange 11 can be made into female threaded holes, and hub bolts can be screwed into them to support and fix the wheel (drive wheel) and braking rotating members such as the disc rotor.

[0019] Furthermore, the outer surface of the hub wheel 9 is provided with an inner ring raceway surface 12a of the outboard side row (one of the rows) in the portion facing the outer ring raceway surface 8a of the axially outer (outboard side) row of the outer ring 2. Additionally, a small diameter step portion 13 is provided at the axially inner end of the outer surface of the hub wheel 9 that faces the outer ring raceway surface 8b of the axially inner (inboard side) row of the outer ring 2.

[0020] The inner ring member 10 is provided with an inner ring raceway surface 12b of the inboard side row (the other row) on its outer circumferential surface. The inner ring member 10 is fitted onto the outer circumferential surface of the small-diameter stepped portion 13 of the hub wheel 9 with its outboard side end face abutting against the stepped surface of the small-diameter stepped portion 13, and is fixed to the hub wheel 9 by its inboard side end face being joined and fixed by the crimping portion 24.

[0021] The rolling elements 4, 4 are provided to roll freely in the space between the outer ring raceway surface 8a and the inner ring raceway surface 12a of the outboard side row, and in the space between the outer ring raceway surface 8b and the inner ring raceway surface 12b of the inboard row, while being held by a pair of retainers 6, 6.

[0022] A seal ring 5 is supported and fixed to the outboard end of the inner circumferential surface of the outer ring 2. The seal ring 5 closes the outboard end opening of the internal space 18, which is located between the inner circumferential surface of the outer ring 2 and the outer circumferential surface of the hub ring 9 and contains a plurality of rolling elements 4, 4. The seal ring 5 slides against the large-diameter stepped portion 20 on the outboard side of the inner ring raceway surface 12a of the outer circumferential surface of the hub ring 9.

[0023] An annular encoder 14 is supported and fixed to the inboard end of the inner ring member 10. The encoder 14 consists of a support ring 26 and an encoder body 27. The support ring 26 is formed in an L-shape in cross-section and an annular shape overall by press-forming a magnetic metal plate, such as a ferritic stainless steel plate such as SUS430 or a rolled steel plate such as SPCC. The outboard portion of the support ring 26 is externally fitted and fixed to the inner ring member 10. The support ring 26 has an annular cross-section that is approximately L-shaped, with an annular ring portion 26a fixed to the inner ring member 10 and a flange portion 26b extending radially inward from the inboard end of the ring portion 26a. The encoder body 27 is made in an annular shape overall from a permanent magnet made by mixing a magnetic material such as ferrite powder into rubber or thermoplastic resin, and is attached and fixed to the inboard side of the flange portion 26b of the support ring 26. On the inboard side (detection surface) of the encoder body 27, S poles and N poles are magnetized alternately and at equal pitches in the circumferential direction.

[0024] A bottomed cylindrical cap 30 is fixed to the inboard end of the outer ring 2, which closes the opening on the inboard side of the outer ring 2.

[0025] As shown in Figure 2, the cap 30 has a cap body 50 made of synthetic resin containing a filler, and a metal core 40 fixed to the cap body 50.

[0026] The cap body 50 is manufactured in a bottomed cylindrical shape by injection molding (axial draw molding) of synthetic resin, and has a roughly disc-shaped resin bottom plate portion 51 and a roughly cylindrical resin tube portion 53 that extends from the radially outer part of the resin bottom plate portion 51 toward the outboard side. The resin bottom plate portion 51 is the bottom portion that closes the axially oriented opening of the resin tube portion 53.

[0027] A thickened portion 52 is provided at a position radially outward from the central axis of the resin base plate portion 51, where the axial thickness is greater than that of other parts (bulging outwards on both sides in the axial direction).

[0028] The thickened portion 52 is provided with an insertion hole 54 that penetrates the thickened portion 52 axially, in the portion facing the detection surface of the encoder body 27 in the axial direction. The insertion hole 54 is for inserting the sensor, and the inner circumferential surface of the insertion hole 54 has an inner diameter that is slightly larger than the outer diameter of the sensor.

[0029] An insert nut 56 is molded and fixed to the radially inner portion of the thick-walled section 52. The insert nut 56 is either a through nut with an internal thread formed on its inner circumferential surface and a through hole extending in the axial direction, or a bottomed cylindrical cap nut with a bottom at the outboard end. With the sensor inserted into the insertion hole 54, the sensor is fixed inside the insertion hole 54 by screwing a bolt (not shown) that passes through a fixing hole provided in the flange portion of the sensor into the insert nut 56.

[0030] The synthetic resin material constituting the cap body 50 is, for example, polyamide 66 resin to which a filler has been added. The filler may be, for example, a fibrous reinforcing material such as glass fiber, carbon fiber, or metal fiber. It is preferable to use long fiber material (for example, 6.0 to 15.0 mm) for the filler. Furthermore, if necessary, the water resistance may be further improved by appropriately adding amorphous aromatic polyamide resin (modified polyamide 6T / 6I) or low water absorption aliphatic polyamide resin (polyamide 11 resin, polyamide 12 resin, polyamide 610 resin, polyamide 612 resin) to the polyamide resin.

[0031] The core metal 40 is made of metal such as stainless steel sheet or rolled steel sheet and is formed in an annular shape. The core metal 40 has an L-shaped cross-section, having a substantially cylindrical core metal tube portion 41 extending in the axial direction and a core metal flange portion 43 extending radially outward from the inboard side end of the core metal tube portion 41. The core metal 40 is mold-fixed to the resin tube portion 53 of the cap body 50. As a result, the core metal 40 is covered by the resin tube portion 53 from its radially outside. Since it is difficult to perform injection molding with the core metal 40 floating above the mold, it is necessary for either the radially outside or radially inside of the core metal 40 to be a locking surface with the mold (a surface not covered by resin). Therefore, in this embodiment, the inner circumferential surface 41a of the core metal tube portion 41 is not covered by resin so that it can be locked to the movable mold during injection molding.

[0032] The resin cylindrical portion 53 of the cap body 50 has a large-diameter portion 55 that covers the core metal flange portion 43 from the radially outside, and a small-diameter portion 57 that covers the core metal cylindrical portion 41 from the radially outside. The outer diameter of the large-diameter portion 55 is larger than the inner diameter of the inner circumferential surface 2a of the inboard end of the outer ring 2. Therefore, the large-diameter portion 55 abuts the inboard end of the outer ring 2 in the axial direction. The outer diameter of the small-diameter portion 57 is slightly larger than the inner diameter of the inner circumferential surface 2a of the inboard end of the outer ring 2. The small-diameter portion 57 is press-fitted into the inner circumferential surface of the inboard end of the outer ring 2. Therefore, the small-diameter portion 57 can also be said to be the resin fitting portion of the cap 30.

[0033] Here, let A be the radial dimension between the outer surface of the core metal flange portion 43 and the outer surface of the large diameter portion 55 (the radial thickness of the large diameter portion 55 covering the outer surface of the core metal flange portion 43), let B be the axial dimension between the outboard side surface of the core metal flange portion 43 and the outboard side surface of the large diameter portion 55 (the axial thickness of the large diameter portion 55 covering the outboard side surface of the core metal flange portion 43), and let C be the axial dimension between the outboard side surface of the core metal cylinder portion 41 and the outboard side surface of the small diameter portion 57 (the axial thickness of the small diameter portion 57 on the outboard side of the core metal cylinder portion 41).

[0034] In this embodiment, by setting the radial dimension A and axial dimension B to small (for example, 0.5 mm to 1.0 mm), the movement of the filler to the small-diameter portion 57, which is the fitting portion, is suppressed. As a result, the filler content in the small-diameter portion 57 of the resin cylinder portion 53 is made smaller than the filler content in the resin bottom plate portion 51.

[0035] Furthermore, by setting the axial dimension C to be larger than the radial dimension A and the axial dimension B (for example, 2.0 to 3.0 mm), the filler in the small-diameter portion 57, which is the fitting portion, is oriented axially, making it easier for the resin to absorb water and preventing material loss in the small-diameter portion 57.

[0036] The gate during injection molding is provided, for example, near the central axis of the resin base plate portion 51, on the resin base plate portion 51 next to the thick-walled portion 52, or on the thick-walled portion 52.

[0037] As described above, according to this embodiment, the resin bottom plate portion 51 has a high filler content and the filler is oriented radially from the gate to prevent water absorption deformation, while the small diameter portion 57 of the resin cylinder portion 53, which is the fitting portion, has a low filler content, allowing some degree of water absorption deformation (water swelling) to occur. However, since the spatial volume between the core metal 40 and the outer ring 2 is constant, water absorption deformation does not actually progress, and the stress generated by water swelling, combined with the decrease in hardness due to water swelling, contributes to improving the fitting force and watertightness, making it possible to obtain a resin end cap with high fitting force and high watertightness.

[0038] [Second Embodiment] Figure 3 is an enlarged view of the main part of the hub unit bearing according to the second embodiment. During injection molding, the resin filler constituting the cap body 50 has difficulty passing through the narrow section, and the filler that does pass through is concentrated on the exit side of the narrow section.

[0039] In the hub unit bearing 1 shown in Figure 3, notches 45 are provided as narrow sections at multiple circumferential locations on the radially outer end of the core metal flange portion 43. As a result, the small diameter portion 57, which serves as the fitting portion, has the filler material oriented axially as a whole, with a lower filler material content than the resin bottom plate portion 51, and the filler material content changes in the circumferential direction. In this embodiment, a large area of ​​the small diameter portion 57 can have a lower filler material content compared to the first embodiment, thus improving the fitting force and watertight performance.

[0040] [Third Embodiment] Figure 4 is an enlarged view of the main part of the hub unit bearing according to the third embodiment. In the hub unit bearing 1 shown in Figure 4, through holes 47 are provided as narrow sections at multiple locations in the circumferential direction at the base of the core metal flange portion 43. According to this embodiment, similar to the second embodiment, the small diameter portion 57, which serves as the fitting portion, has the filler material oriented axially as a whole, with a lower filler material content than the resin bottom plate portion 51, and the filler material content changes in the circumferential direction. Therefore, a large area of ​​the small diameter portion 57 can have a lower filler material content compared to the first embodiment, thus improving the fitting force and watertight performance.

[0041] Furthermore, the present invention is not limited to the embodiments described above, and can be modified and improved as appropriate.

[0042] For example, in the embodiment described above, the insertion hole 54 for inserting the sensor was described as a through hole that penetrates the thickened portion 52, but the insertion hole 54 may not be a through hole.

[0043] Furthermore, the cap 30 does not necessarily have to have a function of supporting the sensor, and the present invention is also suitable, for example, when it is desired to guarantee the axial position of the end face of the cap 30. [Explanation of Symbols]

[0044] 1 Hub unit bearing 2 Outer ring 2a Inner surface 3. Inner Ring 4 Rolling elements 5 Seal ring 7 Stationary flange 8a,8b Outer ring raceway surface 9 Hub Wheel 10 Inner ring member 11 Rotating side flange 11a Through hole 12a, 12b Inner ring raceway surface 13 Small diameter stepped section 14 encoders 17 Hub bolts 18 Interior space 20 Large diameter stepped section 24 Crimping section 26 Support ring 26a Annular section 26b Flange section 27 Encoder unit 30 caps 40 Mandrel 41 Core tube part 41a Inner surface 43 Core metal flange section 45 Notches 47 Through hole 50 Cap Body 51 Resin base plate 52 Thick wall part 53 Resin cylinder part 54 Insertion holes 55 Large diameter section 56 Insert Nuts 57 Small diameter section

Claims

1. An outer ring having a double-row outer ring raceway formed on its inner circumference, An inner ring having a double row of inner ring raceway surfaces formed on its outer surface, A plurality of rolling elements are arranged to roll freely between the double-row inner ring raceway surface and the double-row outer ring raceway surface, A cap is fixed to the inboard-side end of the outer ring and closes the opening on the inboard side of the outer ring, A hub unit bearing equipped with, The cap comprises a cap body made of synthetic resin containing a fibrous filler, and a metal core fixed to the cap body. The cap body is a bottomed cylindrical shape overall, and has a substantially disc-shaped resin bottom plate portion and a substantially cylindrical resin tube portion extending from the radially outer portion of the resin bottom plate portion toward the outboard side. The core metal is annular in shape and has an L-shaped cross-section, comprising a substantially cylindrical core metal tube portion extending in the axial direction and a core metal flange portion extending radially outward from the inboard side end of the core metal tube portion. A thickened portion is provided at a position radially outward from the central axis of the aforementioned resin bottom plate, where the axial thickness is greater than that of other parts. The resin cylinder portion has a large-diameter portion that covers the core metal flange portion from the radially outer side, and a small-diameter portion that covers the core metal cylinder portion from the radially outer side, The small diameter portion of the resin cylinder is fitted inside the inboard end of the outer ring. Let A be the radial dimension between the outer surface of the core metal flange portion and the outer surface of the large diameter portion. Let B be the axial dimension between the outboard side surface of the core metal flange portion and the outboard side surface of the large diameter portion. Let C be the axial dimension between the outboard side surface of the core metal cylinder and the outboard side surface of the small diameter portion. The radial dimension A and the axial dimension B are 0.5 mm to 1.0 mm. The axial dimension C is 2.0 mm to 3.0 mm. The gate during injection molding is provided near the central axis of the resin bottom plate portion, on the resin bottom plate portion next to the thick-walled portion, or on the thick-walled portion. In the small diameter portion of the resin cylinder, the fibrous filler is oriented in the axial direction, and the content of the fibrous filler in the small diameter portion is smaller than the content of the fibrous filler in the resin bottom plate portion. Hub unit bearing.

2. The content of the fibrous filler in the small diameter portion of the resin cylinder changes in the circumferential direction, by providing notches at multiple locations in the circumferential direction at the radial outer end of the core metal flange portion, or by providing through holes at multiple locations in the circumferential direction at the base of the core metal flange portion. The hub unit bearing according to claim 1.

3. Multiple notches are provided at the radially outer end of the core metal flange portion in the circumferential direction. The hub unit bearing according to claim 2.

4. Multiple through holes are provided at the base of the core metal flange portion in the circumferential direction. The hub unit bearing according to claim 2.

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