JP2022152778A - Hub unit bearing for driven wheel with encoder - Google Patents

Abstract

To provide a hub unit bearing for a driven wheel with an encoder which can prevent deterioration of detection accuracy of a rotation speed while securing sealing performance of the interior of the bearing.SOLUTION: An annular projection part 68 of an encoder main body 64 formed of magnetic rubber is provided facing an inner peripheral surface 51c of a cap member 50 at one axial side relative to a detected surface 67 of the encoder main body 64.SELECTED DRAWING: Figure 1

Description

The present invention relates to a driven wheel hub unit bearing with an encoder.

2. Description of the Related Art Hub unit bearings for rotatably supporting wheels of an automobile with respect to a suspension system have conventionally been widely known to include sensors for detecting the rotation speed of the wheels necessary for controlling ABS and the like. As a driven wheel hub unit bearing, the inner ring is crimped or fixed with a nut to a hub wheel having a wheel mounting flange to form a hub. Sealed inner ends are commonly used. In addition, a sealing member is provided at the opening of the bearing space where the rolling elements are arranged to prevent the lubricating grease sealed in the bearing space from leaking to the outside, thereby ensuring the lubricity of the bearing. .

For example, in the wheel bearing device described in Patent Document 1, a seal lip made of magnetic rubber, which is the material of the encoder, is provided on the outer diameter portion of the encoder, and the seal lip is placed in a groove provided on the inner peripheral surface of the outer ring. It is arranged to form a labyrinth to prevent lubricating grease from flowing out from the bearing space where the rolling elements are accommodated to the internal space sealed by the end cap or knuckle, thereby preventing deterioration of the lubricity of the bearing. is disclosed.

JP 2010-127296 A

However, according to the wheel bearing device of Patent Document 1, the inner peripheral surface of the outer ring made of a magnetic material and the encoder provided with magnetic rubber, particularly the seal lip, are arranged close to each other. For this reason, the magnetic flux from the surface of the encoder is attracted to the outer ring, and the magnetic flux density at the sensor position may decrease, resulting in a decrease in magnetic flux detection accuracy, and there is room for improvement.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and its object is to provide a hub unit bearing for a driven wheel with an encoder that can prevent a decrease in rotational speed detection accuracy while ensuring sealing performance inside the bearing. to do.

The above objects of the present invention are achieved by the following configurations.
[1] an outer ring having a double-row outer ring raceway on its inner peripheral surface;
A hub wheel having a wheel mounting flange on one axial side and a small diameter stepped portion formed on the other axial side, and at least one inner ring press-fitted to the small diameter stepped portion of the hub wheel, a hub formed with a double-row inner ring raceway facing the double-row outer ring raceway;
a plurality of rolling elements rollably disposed between the double-row outer ring raceway and the double-row inner ring raceway;
a cap member attached to the outer ring so as to block an opening on the other axial side of the outer ring;
an axial encoder having a core bar externally fitted and fixed to the shoulder portion of the inner ring, and a ring-shaped encoder main body supported by the core bar and made of magnetic rubber;
A hub unit bearing for a driven wheel with an encoder, comprising:
The outer diameter portion of the axial encoder is made of the magnetic rubber that is formed integrally with the encoder body and faces the inner peripheral surface of the cap member on one axial side of the detected surface of the encoder body. provided with an annular protrusion,
Hub unit bearing for driven wheels with encoder.

According to the encoder-equipped driven wheel hub unit bearing of the present invention, the annular protrusion made of magnetic rubber molded integrally with the encoder main body is positioned inside the cap member on one axial side of the detected surface of the encoder main body. Since it is provided so as to face the peripheral surface, it is possible to prevent a decrease in rotational speed detection accuracy while ensuring sealing performance inside the bearing.

1 is a cross-sectional view of a main part of an encoder-equipped driven wheel hub unit bearing according to a first embodiment of the present invention; FIG. FIG. 2 is an enlarged view of the portion enclosed by circle II in FIG. 1; FIG. 5 is a cross-sectional view showing the manufacturing process of the axial encoder; FIG. 3 is a cross-sectional view of a portion corresponding to FIG. 2 of an encoder-equipped driven wheel hub unit bearing according to a second embodiment of the present invention; FIG. 3 is a cross-sectional view of a portion corresponding to FIG. 2 of an encoder-equipped driven wheel hub unit bearing according to a third embodiment of the present invention;

Hereinafter, each embodiment of the hub unit bearing for driven wheel with encoder according to the present invention will be described in detail based on the drawings.

(First embodiment)
As shown in FIG. 1, an encoder-equipped driven wheel hub unit bearing 10 of the present embodiment rotatably supports a wheel, which is a driven wheel, with respect to a suspension device such as a knuckle, and detects the rotational speed of the wheel. A hub 30, which is a rotating ring, is rotatably supported via a plurality of rolling elements 40 on the inner diameter side of an outer ring 20, which is a stationary ring.

The outer ring 20 is made of ferrous metal, which is a magnetic material, and has a mounting flange 22 on its outer peripheral surface that is coupled and fixed to a knuckle (not shown) that constitutes a suspension system, and a double-row outer ring raceway 21a on its inner peripheral surface. , 21b.

The hub 30 is formed by fitting an inner ring 32 to a small-diameter stepped portion 34 of a hub ring 31 and connecting and fixing the inner ring 32 with a caulking portion, and has double-row inner ring raceways 35a and 35b on the outer peripheral surface. A wheel mounting flange 36 for supporting the wheel is provided on one axial side of the hub wheel 31 and protruding in one axial direction beyond the one axial end opening of the outer ring 20 . A plurality of rolling elements 40 are provided between the double-row outer ring raceways 21a and 21b and the double-row inner ring raceways 35a and 35b, respectively.
The term "one side in the axial direction" as used herein refers to the side on the outside in the width direction of the vehicle body when the driven wheel hub unit bearing 10 with encoder is assembled to the vehicle with respect to the axial direction of the hub unit bearing. , 4, 5 to the left. On the contrary, the right side in FIGS. 1, 2, 4 and 5, which is the inner side in the width direction of the vehicle body, is referred to as the other side in the axial direction.

A seal ring 13 closes the end opening on one side in the axial direction of the bearing space 12 that accommodates the rolling elements 40 between the inner peripheral surface of the outer ring 20 and the outer peripheral surface of the hub 30 . On the other hand, a bottomed cylindrical cap member 50 is attached to the other end of the outer ring 20 in the axial direction to close the end opening of the outer ring 20 on the other axial side.

The cap member 50 is composed of a cap body 51 made of synthetic resin and having a cylindrical shape with a bottom, and a metal ring 52 fixed to the cap body 51 by molding. As shown in FIG. 2, the cap main body 51 is made by injection molding (axial draw molding) synthetic resin into a bottomed cylindrical shape as a whole. and a bottom plate portion 51b that closes the sides. A magnetic detection sensor 70 is disposed on the bottom plate portion 51b so as to axially face a surface 67 to be detected of an axial encoder 60, which will be described later.

The metal ring 52 is made of a stainless steel plate, a rolled steel plate, or the like, and has an L-shaped cross section and an annular shape as a whole. A flange portion provided on the other side in the axial direction of the metal ring 52 is molded and fixed inside the cylindrical portion 51a.

The cap member 50 has a cylindrical portion provided on one side in the axial direction of the metal ring 52 that is internally fitted to the inner peripheral surface of the end portion on the other side in the axial direction of the outer ring 20, and the axial end faces of the cap member 50 are in contact with each other. , is mounted on the outer ring 20 . At this time, the mating surfaces of the outer ring 20 and the metal ring 52 are waterproofed by potting to prevent lubricant from leaking from the mating surfaces and muddy water from entering from the outside.

An annular axial encoder 60 that constitutes a rotation speed detection device is fixed to the other axial end of the inner ring 32 . The axial encoder 60 includes a core metal 61 made of a magnetic material and serving as a back yoke of the encoder body 64 , and an annular encoder body 64 made of magnetic rubber vulcanized to the core metal 61 . The core bar 61 is formed into an L-shaped cross section and an annular shape as a whole by pressing a ferritic stainless steel plate such as SUS430 or a rolled steel plate such as SPCC. and a circular ring portion 63 formed at the end portion on the other side in the direction.

The encoder main body 64 is made of a permanent magnet in which a magnetic material such as ferrite powder is mixed in rubber, and is formed in a ring shape as a whole. Made of magnetic rubber. The magnetic rubber fixed to the end surface 63a of the circular ring portion 63 is magnetized with N poles and S poles alternately in the circumferential direction at equal pitches to form a surface 67 to be detected. A magnetic flux signal entering and exiting the surface 67 to be detected is detected by a magnetic detection sensor 70 provided on the cap member 50 .

The magnetic rubber fixed to the outer diameter surface of the cylindrical portion 62 protrudes radially outward at a position radially superimposed on the encoder main body 64 on one axial side of the detected surface 67 of the encoder main body 64 . An annular protrusion 68 is formed. The reason why the annular protrusion 68 overlaps the encoder body 64 in the radial direction is to facilitate molding as described below.

The axial encoder 60 is fixed to the inner ring 32 by externally fitting and fixing the cylindrical portion 62 onto the shoulder portion outer peripheral surface 37 of the inner ring 32 . At this time, the annular projecting portion 68 of the axial encoder 60 is arranged close to the inner peripheral surface 51c of the cylindrical portion 51a of the cap member 50 to form a labyrinth, or is in sliding contact with the inner peripheral surface 51c so as to extend from the bearing space 12. Prevents leakage of lubricating grease.

As shown in FIG. 3, the encoder main body 64 made of magnetic rubber is made by inserting the metal core 61 into the cavity 73 of a pair of molds 71 and 72 and injecting and vulcanizing the magnetic rubber. molded. When the magnetic rubber is vulcanized, the molten magnetic rubber can only be stopped on a flat surface, and the magnetic rubber is fragile. The outer peripheral surface 62a of is covered with magnetic rubber.

According to the driven wheel hub unit bearing 10 with an encoder configured as described above, the annular protrusion 68 is formed on the inner peripheral surface 51c of the cap member 50 without bringing the encoder main body 64 close to the outer ring 20 made of a magnetic material. Can be placed in close proximity. As a result, the magnetic flux signal coming in and out of the detected surface 67 of the encoder body 64 is attracted to the outer ring 20 made of a magnetic material, and the magnetic flux density at the sensor position decreases. As a result, the rotational speed detection accuracy decreases. can be prevented. Furthermore, the annular projection 68 can prevent the lubricating grease from flowing out of the bearing space 12 into the internal space between the hub 30 and the cap member 50, thereby ensuring sealing performance inside the bearing.

(Second embodiment)
FIG. 4 is a cross-sectional view of a main portion of a driven wheel hub unit bearing with an encoder according to a second embodiment of the present invention. In the axial encoder 60a of the encoder-equipped driven wheel hub unit bearing 10 of the present embodiment, the annular protrusion 68a having a triangular cross-section is offset from the outer diameter side of the encoder main body 64 to one axial side. It is formed on the outer peripheral surface 62a.

As described above, the annular protrusion 68a does not need to be provided on the outer diameter side of the encoder body 64 so as to overlap the encoder body 64 in the radial direction. For example, it can be provided at any axial position. In this case, the parting line of the pair of molds 71 and 72 is preferably set so as to pass through the vertices of the triangular annular protrusion 68a in order to facilitate the removal of the mold.

In this case as well, by providing an annular protrusion 68a at a position on one side in the axial direction (leftward in FIG. 3) from the surface 67 to be detected of the encoder body 64, the magnetic flux signal entering and exiting the surface 67 to be detected is made of magnetic rubber. It is possible to prevent the magnetic flux density at the sensor position from being attracted to the annular protrusion 68a and the magnetic flux signal accuracy from deteriorating as a result.
Other configurations and actions are the same as those of the above embodiment.

(Third embodiment)
FIG. 5 is a cross-sectional view of a main portion of a driven wheel hub unit bearing with an encoder according to a third embodiment of the present invention. In the axial encoder 60b of the encoder-equipped driven wheel hub unit bearing 10 of the present embodiment, the core metal 61 includes a cylindrical portion 62 externally fitted and fixed to the shoulder portion outer peripheral surface 37 of the inner ring 32, and a circular portion to which the encoder main body 64 is attached. It has a tapered portion 69 between it and the ring portion 63 .

Further, in the axial encoder 60b of this embodiment, a vulcanization die is driven into the vicinity of the boundary between the cylindrical portion 62 and the tapered portion 69 to stop the flow of the molten magnetic rubber and form the annular protrusion 68b. Accordingly, the annular protrusion 68b is provided at a position radially overlapping the tapered portion 69 or the encoder main body 64. As shown in FIG.

In this case, although the annular projection 68b needs to be slightly forced out, it is not necessary to cover the cylindrical portion 62, so the amount of magnetic rubber used can be reduced, leading to cost reduction.
Other configurations and actions are the same as those of the above embodiment.

It should be noted that the present invention is not limited to the above-described embodiments, and can be modified, improved, etc. as appropriate.
For example, in the above embodiment, the cap member is a sensor cap with a built-in sensor, but it may be an end cap. .
Further, in the hub of the present invention, the inner ring and the hub ring each have an inner ring raceway. However, the present invention is not limited to this. may

As described above, this specification discloses the following matters.
(1) an outer ring having a double-row outer ring raceway on its inner peripheral surface;
A hub wheel having a wheel mounting flange on one axial side and a small diameter stepped portion formed on the other axial side, and at least one inner ring press-fitted to the small diameter stepped portion of the hub wheel, a hub formed with a double-row inner ring raceway facing the double-row outer ring raceway;
a plurality of rolling elements rollably disposed between the double-row outer ring raceway and the double-row inner ring raceway;
a cap member attached to the outer ring so as to block an opening on the other axial side of the outer ring;
an axial encoder having a core bar externally fitted and fixed to the shoulder portion of the inner ring, and a ring-shaped encoder main body supported by the core bar and made of magnetic rubber;
A hub unit bearing for a driven wheel with an encoder, comprising:
The outer diameter portion of the axial encoder is made of the magnetic rubber that is formed integrally with the encoder body and faces the inner peripheral surface of the cap member on one axial side of the detected surface of the encoder body. provided with an annular protrusion,
Hub unit bearing for driven wheels with encoder.
According to this configuration, the annular protrusion of the encoder main body made of magnetic rubber is provided on one side in the axial direction of the surface to be detected of the encoder main body so as to face the inner peripheral surface of the cap member. The magnetic flux from the outer ring is attracted to the outer ring, which is a magnetic material, and it is possible to prevent the deterioration of the magnetic flux detection accuracy due to the reduction of the magnetic flux density at the sensor position.

(2) The core bar includes a cylindrical portion externally fitted and fixed to the shoulder portion of the inner ring, a circular ring portion to which the encoder body is attached, and a taper provided between the cylindrical portion and the circular ring portion. and
The annular protrusion is provided at a position radially overlapping the tapered portion or the encoder body,
A driven wheel hub unit bearing with an encoder according to (1).
According to this configuration, the amount of magnetic rubber used can be reduced by providing the annular protrusion at a position radially superimposed on the tapered portion or the encoder main body.

10 Encoder driven wheel hub unit bearing 20 Outer ring 21a, 21b Outer ring raceway 30 Hub 31 Hub ring 32 Inner ring 34 Small diameter stepped portions 35a, 35b Inner ring raceway 36 Wheel mounting flange 37 Shoulder outer peripheral surface 40 Rolling element 50 Cap member 51c Cap member inner peripheral surfaces 60, 60a, 60b of axial encoder 61 core metal 62 cylindrical portion 62a outer peripheral surface (outer diameter portion of axial encoder)
63 Circular ring portion 64 Encoder body 67 Surfaces to be detected 68, 68a, 68b Annular protrusion 69 Tapered portion

Claims (2)

an outer ring having a double-row outer ring raceway on its inner peripheral surface;
A hub wheel having a wheel mounting flange on one axial side and a small diameter stepped portion formed on the other axial side, and at least one inner ring press-fitted to the small diameter stepped portion of the hub wheel, a hub formed with a double-row inner ring raceway facing the double-row outer ring raceway;
a plurality of rolling elements rollably disposed between the double-row outer ring raceway and the double-row inner ring raceway;
a cap member attached to the outer ring so as to block an opening on the other axial side of the outer ring;
an axial encoder having a core bar externally fitted and fixed to the shoulder portion of the inner ring, and a ring-shaped encoder main body supported by the core bar and made of magnetic rubber;
A hub unit bearing for a driven wheel with an encoder, comprising:
The outer diameter portion of the axial encoder is made of the magnetic rubber that is formed integrally with the encoder body and faces the inner peripheral surface of the cap member on one axial side of the detected surface of the encoder body. provided with an annular protrusion,
Hub unit bearing for driven wheels with encoder. The core bar includes a cylindrical portion externally fitted and fixed to the shoulder portion of the inner ring, a circular ring portion to which the encoder body is attached, a tapered portion provided between the cylindrical portion and the circular ring portion, has
The annular protrusion is provided at a position radially overlapping the tapered portion or the encoder body,
A hub unit bearing for a driven wheel with an encoder according to claim 1.

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