JP6852825B2 - Hub unit bearing - Google Patents

Description

The present invention relates to a hub unit bearing that rotatably supports a wheel (driving wheel) of an automobile with respect to a suspension device.

With a rotation speed detection device, which is a combination of a hub unit bearing that rotatably supports the wheels of an automobile with respect to a suspension device, and a rotation speed detection device for detecting the rotation speed of the wheels required for control of ABS or the like. Hub unit bearings have been widely used in the past.

FIG. 8 shows the one described in Patent Document 1 as an example of the conventional structure of the hub unit bearing with the rotation speed detection device. The hub unit bearing 1 with a rotation speed detection device has a hub 3 that rotates together with the wheels while supporting the wheels on the inner diameter side of an outer ring 2 that is supported and fixed to a suspension device (not shown) via a plurality of rolling elements 4. And supports it rotatably. A fixed side flange 5 is provided on the outer peripheral surface of the outer ring 2 so as to be coupled and fixed to the suspension device (knuckle). A rotating side flange 6 for supporting and fixing the wheel and the brake rotor is provided on the outboard side portion of the outer peripheral surface of the hub 3. Regarding the axial direction, the “outboard (outside)” refers to the side that is outside in the width direction of the vehicle body when assembled to the vehicle, and refers to the left side in FIGS. 1, 2, 4, 6, and 8. On the contrary, the right side of FIGS. 1, 2, 4, 6 and 8, which is the center side in the width direction of the vehicle body, is referred to as "inboard (inside)".

The seal ring 7 closes the outboard end opening of the space where each rolling element 4 is installed between the inner peripheral surface of the outer ring 2 and the outer peripheral surface of the hub 3. On the other hand, the inboard end opening of the outer ring 2 is closed by the bottomed cylindrical bearing cap 8. The bearing cap 8 is composed of a cap body 9 made of synthetic resin and having a bottomed cylindrical shape as a whole, and a metal ring 10 and a nut 11 molded and fixed to the cap body 9 (fixed by insert molding). ..
The cap body 9 includes a resin cylinder portion 12 and a resin bottom plate portion 13 provided so as to close the inboard end portion of the resin cylinder portion 12. The bearing cap 8 is attached to the inboard end of the outer ring 2 by internally fitting and fixing the metal ring 10 molded and fixed to the resin cylinder 12 to the inboard end of the outer ring 2.

An annular encoder 14 constituting the rotation speed detection device is supported and fixed coaxially with the hub 3 at the inboard end of the hub 3. A columnar sensor 15 constituting the rotation speed detection device is supported and fixed to the resin bottom plate portion 13. The sensor 15 is made of synthetic resin, has a magnetic detection element embedded in the tip portion, and has a mounting flange portion 19 at the base end portion. A thick portion 16 having a larger wall thickness in the axial direction than the other portion is provided in a part of the resin bottom plate portion 13 in the circumferential direction. The thick portion 16 has an insertion hole 17 that penetrates in the axial direction in a portion that faces the encoder 14 in the axial direction, and a nut 11 is molded and fixed in a portion that is adjacent to the insertion hole 17. Then, with the sensor 15 inserted into the insertion hole 17, the bolt 20 through which the mounting flange portion 19 is inserted is screwed into the nut 11.

When using the hub unit bearing 1 with a rotation speed detection device, the fixed side flange 5 of the outer ring 2 is coupled and fixed to the suspension device (knuckle), and the wheels are fixed to the rotation side flange 6 of the hub 3 to fix the suspension device. The wheel is rotatably supported. When the wheel rotates, the S pole and the N pole arranged in the encoder 14 alternately pass in the vicinity of the detection element held by the sensor 15, and the output signal of the sensor 15 changes. Since the frequency at which the output signal of the sensor 15 changes is proportional to the number of rotations of the wheels, ABS and TCS can be appropriately controlled by sending the output signal to a controller (not shown).

The bottomed cylindrical cap body 9 made of synthetic resin can be manufactured in a more complicated shape than the metal cap, and can be mass-produced by injection molding in response to mold fixing of the nut 11. .. Therefore, the bearing cap 8 not only closes the inboard end opening of the outer ring 2, but also has a function as a sensor holder of the sensor 15 constituting the rotation speed detection device.
However, since the resin material has a thermal conductivity of about several tens to several hundredths that of the metal material, the resin bearing cap 8 receives heat from the brake rotor attached to the rotating side flange 6. The cooling performance of radiating heat to the external space through the cap body 9 is very low. Therefore, in the hub unit bearing 1 to which the resin bearing cap 8 is attached, the temperature inside the bearing is likely to rise as compared with the hub unit bearing to which the metal bearing cap is attached, and the lubricant and the seal are deteriorated by heat. If the temperature rises sharply, the bearing cap may come off due to the rise in the bearing internal pressure. Further, when the hub unit bearing returns to room temperature, the seal lip of the seal ring 7 sticks to the sliding contact surface of the hub 3 due to the decrease in the bearing internal pressure, causing problems such as an increase in rotational torque and wear of the seal lip. There was a risk of doing so.

The resin material constituting the cap body 9 can also be used as a reinforcing material by combining carbon fibers and carbon nanotubes having high thermal conductivity, metal fibers such as copper, and the like. However, in the case of the shape (flat plate shape) of the resin bottom plate portion 13 of the bearing cap 8 shown in FIG. 8, the reinforcing material is oriented in the flow direction (diameter direction or circumferential direction) of the resin material, and is oriented in the axial direction. Not oriented. Therefore, the reinforcing material cannot conduct heat in the axial direction, and the effect of improving the cooling performance of the cap body 9 is small.

Japanese Unexamined Patent Publication No. 2015-045350

An object of the present invention is to improve the cooling performance of a bearing cap having a cap body made of synthetic resin and suppress the temperature rise of the hub unit bearing.

In order to solve the above problems, the hub unit bearing of the present invention has an outer ring having a double row of outer ring races on the inner peripheral surface and a double row of inner ring races on the outer peripheral surface, and supports the wheels on the outboard side. A hub provided with a flange on the rotating side for this purpose, a plurality of rolling elements provided in each row between each outer ring track and each inner ring track, and a bearing that closes the inboard end opening of the outer ring. With a cap,
The bearing cap has a metal fitting core metal and a cap body made of synthetic resin, and the cap body has a bottomed cylindrical shape as a whole, and has a cylindrical resin cylinder portion and the resin cylinder. The fitting core metal has a resin bottom plate portion that closes the opening of the portion, the inboard side portion is coupled and fixed to the resin cylinder portion, and the outboard side portion is fitted to the inboard end portion of the outer ring. It fits.

In particular, in the hub unit bearing of the present invention, the synthetic resin is a composite of a reinforcing material having a higher thermal conductivity than the resin material, and the resin bottom plate portion extends axially from both side surfaces in the axial direction. It has protrusions provided symmetrically in the axial direction, and the reinforcing material is axially oriented inside the protrusions provided symmetrically in the axial direction.

According to the bearing cap of the present invention configured as described above, the cooling performance of the bearing cap having the cap body made of synthetic resin is improved, and the temperature rise of the hub unit bearing is suppressed, so that the lubricant and the seal are deteriorated. Also, it is possible to prevent an increase in rotational torque.

FIG. 3 is a cross-sectional view of a hub unit bearing showing the first embodiment. FIG. 3 is a cross-sectional view of the bearing cap shown in FIG. The view which saw the bearing cap of FIG. 2 from the inboard side (right side). FIG. 3 is a cross-sectional view of a bearing cap showing a second embodiment. The view which saw the bearing cap of FIG. 4 from the inboard side (right side). FIG. 3 is a cross-sectional view of a bearing cap showing a third embodiment. The view which saw the bearing cap of FIG. 6 from the inboard side (right side). FIG. 5 is a cross-sectional view showing an example of a hub unit bearing having a conventional structure.

[First Embodiment]
1 to 3 show the first embodiment of the present invention. The hub unit bearing 1a incorporating the bearing cap 8a 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 rotation speed of the wheel. A hub 3 which is a rotating wheel is rotatably supported on the inner diameter side of the outer ring 2 via a plurality of rolling elements 4.

The outer ring 2 has a fixed side flange 5 that is coupled and fixed to a knuckle (not shown) constituting the suspension device on the outer peripheral surface, and has a double row of outer ring tracks 21a and 21b on the inner peripheral surface. The hub 3 is formed by connecting and fixing the hub main body 22 and the inner ring 23 by a caulking portion 24, and has a double-row inner ring tracks 25a and 25b on the outer peripheral surface. On the outboard side of the hub body 22, a rotating side flange 6 for supporting the wheels is provided at a portion of the outer ring 2 protruding toward the outboard side from the outboard end opening. A plurality of rolling elements 4 are provided between the outer ring raceways 21a and 21b and the inner ring raceways 25a and 25b, respectively.

The annular encoder 14 constituting the rotation speed detection device is supported and fixed to the inboard end of the inner ring 23. The encoder 14 is composed of a support ring 26 and an encoder main body 27. The support ring 26 is formed in an annular shape with an L-shaped cross section by pressing a ferrite stainless steel plate such as SUS430 or a rolled steel plate such as SPCC. The outboard side portion of the support ring 26 is externally fitted and fixed to the inner ring 23. The encoder main body 27 is entirely formed in a ring shape by a permanent magnet mixed with a magnetic material such as ferrite powder, and is attached and fixed to the inboard side surface of the support ring 26. On the inboard side surface (detected surface) of the encoder main body 27, S poles and N poles are arranged alternately and at equal pitches in the circumferential direction.

The outboard end opening of the internal space 18 in which each rolling element 4 is installed between the inner peripheral surface of the outer ring 2 and the outer peripheral surface of the hub 3 is closed by the seal ring 7. On the other hand, a bottomed cylindrical bearing cap 8a is attached to the inboard end of the outer ring 2 to close the inboard end opening of the outer ring 2.
The bearing cap 8a is composed of a cap body 9a made of synthetic resin and having a bottomed cylindrical shape, and a metal ring 10a and a nut 11a molded and fixed to the cap body 9a. The cap body 9a is entirely formed into a bottomed cylindrical shape by injection molding (axial draw molding) of synthetic resin, and is a resin that closes the opening of the resin cylinder portion 12a and the axial intermediate portion of the resin cylinder portion 12a. It is provided with a bottom plate portion 13a.

As the synthetic resin material constituting the cap body 9a, for example, a polyamide 66 resin is compounded with carbon fiber, carbon nanotube, or a metal fiber such as copper, which is superior in thermal conductivity to the resin material, as a fibrous reinforcing material. The fiber-reinforced polyamide resin material is used. If necessary, the polyamide resin may be an amorphous aromatic polyamide resin (modified polyamide 6T / 6I) or a low water absorption aliphatic polyamide resin (polyamide 11 resin, polyamide 12 resin, polyamide 610 resin, polyamide 612 resin). The water resistance may be further improved by adding it as appropriate. In any case, the cap body 9a is molded by a synthetic resin material in which a reinforcing material having a higher thermal conductivity than the resin material is compounded.

The metal ring 10a is made of a stainless steel plate, a rolled steel plate, or the like, has an L-shaped cross section, and is formed in an annular shape as a whole. The flange portion provided on the inboard side of the metal ring 10a is molded and fixed inside the resin cylinder portion 12a. A locking groove is formed on the inner diameter side of the end surface of the outboard of the resin cylinder portion 12a over the entire circumference, and the O-ring 28 is locked in the locking groove.

The entire resin bottom plate portion 13a is formed in a substantially disk shape. A thick wall portion 16a having a larger wall thickness in the axial direction (bulging toward both sides in the axial direction) is provided at the upper end portion of the resin bottom plate portion 13a. An insertion hole 17a that axially penetrates the thick portion 16a is provided at the upper end portion of the thick portion 16a so as to face the detected surface of the encoder main body 27 in the axial direction. The insertion hole 17a is for inserting the sensor 15 (see FIG. 8), and the inner peripheral surface of the insertion hole 17a has an inner diameter dimension slightly larger than the outer diameter dimension of the sensor 15.
A nut 11a is molded and fixed to the lower end of the thick portion 16a. The nut 11a is a bottomed cylindrical bag nut having a bottom portion at the end of the outboard, and a female screw is formed on the inner peripheral surface.

The shape of the thick portion 16a seen from the axial direction is an oval shape that is long in the vertical direction, and is sandwiched between the insertion hole 17a and the nut 11a, and only on the outboard side surface of the thick portion 16a. An open meat removal portion 30 is provided. By providing the thinning portion 30, the wall thickness of each portion (the peripheral portion of the insertion hole 17a and the nut 11a) constituting the thick portion 16a is made as thin and uniform as possible. As a result, the solidification time of the resin material when the cap body 9a is axially draw-molded is shortened to improve the line tact, and the deformation of the cap body 9a due to sink marks or the like is prevented. The shape of the thinning portion 30 is a quadrangular pyramid that tapers toward the inboard side.

In order to improve the cooling performance of the cap body 9a made of synthetic resin, a plurality of annular protrusions 32a and 32b are provided on both side surfaces of the resin bottom plate portion 13a in the axial direction, respectively. Each of the annular protrusions 32a and 32b is a plurality of (four in the illustrated example) cylindrical ribs having different diameters arranged concentrically with the resin bottom plate portion 13a. The radial width of each annular projection 32a, 32b is substantially the same as the radial distance of the annular projections 32a, 32b adjacent to each other in the radial direction, and the annular projections 32a, 32b are arranged at approximately equal intervals in the radial direction. There is.
The annular protrusions 32a and 32b have the same amount of protrusion in the axial direction, and the annular protrusion 32a on the outboard side and the annular protrusion 32b on the inboard side are related to a virtual plane located at the center of the resin bottom plate portion 13 in the axial direction. It is symmetric. The tip surface (inboard side surface) of the annular protrusion 32b on the inboard side is located on the same virtual plane as the inboard side surface of the resin cylinder portion 12a.

A substantially semi-oval convex portion 31 is provided on the inboard side surface of the resin bottom plate portion 13a and adjacent to the thick portion 16a. Then, on the inboard side surface of the convex portion 31, a substantially central portion of the cap body 9a is set as a gate position when the cap body 9a is injection-molded by an axial draw.
When the cap body 9a is injection-molded, a molding space is formed by bringing the movable mold closer to the axial direction and abutting the fixed mold (not shown). Then, the molten resin (the molten resin by heating the resin material containing the reinforcing material as described above) is sent into the molding space through the gate provided in the movable mold.

Since the position of the gate when molding the cap body 9a is provided at a substantially central portion of the cap body 9a, the molten resin injected from the gate spreads radially outward from the central portion. Then, in the middle of the resin bottom plate portion 13a in which the molten resin spreads radially, the annular protrusions 32a and 32b projecting to both sides (outboard side and inboard side) in the axial direction so as to penetrate the resin bottom plate portion 13a in the axial direction, respectively. Exists.
The molten resin injected from the gate moves the resin bottom plate portion 13a radially outward, and then splits into two axially at the annular projections 32a and 32b and moves in the axial direction. Therefore, the reinforcing material composited with the resin filled in the annular protrusions 32a and 32b is axially oriented inside the annular protrusions 32a and 32b.

The bearing cap 8a has the outboard side of the metal ring 10a fitted inwardly on the inner peripheral surface of the inboard end portion of the outer ring 2, and the outboard end surface of the resin cylinder portion 12a is abutted against the inboard end surface of the outer ring 2. It is attached to the outer ring 2. At this time, the fitting portion between the outer ring 2 and the bearing cap 8a is sealed by sandwiching the O-ring 28 between the inboard end surface of the outer ring 2 and the resin cylinder portion 12a.
In the state where the bearing cap 8a is attached to the outer ring 2, the annular projection 32a on the outboard side is in contact with the air sealed in the internal space 18, and the annular projection 32b on the inboard side is the air in the external space. It is in contact with (atmosphere).

The concentrically formed annular protrusions 32a and 32b have a large surface area and facilitate the transfer of heat to the air in contact with the annular protrusions 32a and 32b. Therefore, the annular protrusion 32a on the outboard side is sealed in the internal space 18 of the hub unit bearing 1a, and is in contact with the air that has become a rotating air flow by the rotating hub 3 (encoder 14), and the heat inside the bearing is dissipated. Can be collected quickly. The collected heat is axially oriented inside the annular projections 32a and 32b, and is quickly transferred to the inboard side through the reinforcing material having high thermal conductivity. The heat transferred to the annular projection 32b on the inboard side is dissipated to the air in the external space in contact with the annular projection 32b on the inboard side.

According to the hub unit bearing 1a of the present embodiment configured as described above, the cooling performance of the bearing cap having the cap body made of synthetic resin is enhanced, and the temperature rise of the hub unit bearing is suppressed, thereby providing a lubricant or a lubricant. It is possible to prevent deterioration of the seal and increase in rotational torque.
That is, the resin bottom plate portion 13a of the cap body 9a formed of a resin material containing a reinforcing material having excellent thermal conductivity includes annular projections 32a and 32b protruding in the axial direction, and the annular projections 32a and 32b of the annular projections 32a and 32b. A fibrous reinforcing material is axially oriented inside. The heat inside the bearing is efficiently absorbed from the annular projection 32a on the outboard side, which has a large surface area, and then is rapidly transferred to the annular projection 32b on the inboard side through the reinforcing material having excellent thermal conductivity. The annular protrusion 32b on the inboard side, which has a large surface area, can efficiently dissipate heat to the external space. As described above, since the bearing cap 8a has a high cooling performance of quickly dissipating the heat inside the bearing to the external space, it is possible to suppress the temperature rise of the hub unit bearing 1a. Therefore, deterioration of the lubricant and the seal due to an increase in the bearing temperature can be prevented, and an increase in the rotational torque due to a change in the bearing internal pressure can be suppressed.

[Second Embodiment]
FIGS. 4 and 5 show a second embodiment of the present invention. The bearing cap 8b of the present embodiment is provided with a plurality of columnar protrusions 33a and 33b protruding in the axial direction on both sides of the resin bottom plate portion 13b in the axial direction. Each of the columnar protrusions 33a and 33b has a cylindrical shape, and is arranged vertically and horizontally on the side surface of the resin bottom plate portion 13b like a grid. Inside the columnar protrusions 33a and 33b, a fibrous reinforcing material is provided. It is oriented in the axial direction.

The heat absorbed by the columnar protrusions 33a on the outboard side is quickly transmitted through the reinforcing material having excellent thermal conductivity, and is dissipated from the columnar protrusions 33b on the inboard side to the external space. Since the surface areas of the large number of columnar protrusions 33a and 33b formed on the side surfaces of the resin bottom plate portion 13b are larger than those of the annular protrusions 32a and 32b of the first embodiment, the cooling performance of the hub unit bearing can be further improved. Other configurations and operations are the same as in the case of the first embodiment described above.

[Third Embodiment]
6 and 7 show a third embodiment of the present invention. The bearing cap 8c of the present embodiment has a corrugated shape in which the cross section of the resin bottom plate portion 13c undulates radially outward from the central portion of the resin bottom plate portion 13c. When the cap body 9c is molded by injection molding, the molten resin injected from the gate of the convex portion 31 moves along the corrugated shape, so that the fibrous reinforcing material is oriented in a corrugated shape along the resin bottom plate portion 13c. Has been done. Therefore, in the axially central portion of the resin bottom plate portion 13c, the reinforcing material is oriented in the axial direction.

The heat collected at the top 34a on the outboard side (part with high heat collection effect) conducts the reinforcing material with high thermal conductivity and is quickly transferred to the top 34b on the inboard side (part with high heat dissipation effect). A hub unit bearing with high cooling performance can be obtained. Other configurations and operations are the same as in the case of the first embodiment described above.

The hub unit bearing of the present invention can be suitably used as a bearing unit that rotatably supports the wheels of an automobile.

1, 1a Hub unit bearing 2 Outer ring 3 Hub 4 Rolling element 5 Fixed side flange 6 Rotating side flange 7 Seal ring 8, 8a to 8c Bearing cap 9, 9a to 9c Cap body 10, 10a Metal ring 11, 11a Nut 12, 12a Resin cylinder part 13, 13a ~ 13c Resin bottom plate part 14 Encoder 15 Sensor 16, 16a Thick part 17, 17a Insertion hole 18 Internal space 19 Mounting flange part 20 Bolt 21a, 21b Outer ring track 22 Hub body 23 Inner ring 24 Caulking part 25a, 25b Inner ring orbit 26 Support ring 27 Encoder body 28 O-ring 30 Thickening part 31 Convex part 32a, 32b Annular protrusion 33a, 33b Columnar protrusion 34a, 34b Top

Claims (1)

An outer ring having a double row of outer ring tracks on the inner peripheral surface,
A hub that has a double row of inner ring tracks on the outer peripheral surface and a rotating side flange for supporting the wheels on the outboard side.
A plurality of rolling elements provided in each row between the outer ring orbits and the inner ring orbits, and
A bearing cap that closes the inboard end opening of the outer ring is provided.
The bearing cap has a metal fitting core and a cap body made of synthetic resin.
The cap body has a bottomed cylindrical shape as a whole, and has a cylindrical resin cylinder portion and a resin bottom plate portion that closes an opening of the resin cylinder portion.
The fitting core metal is a hub unit bearing in which the inboard side portion is coupled and fixed to the resin cylinder portion and the outboard side portion is fitted to the inboard end portion of the outer ring.
The synthetic resin is a composite of a reinforcing material having a higher thermal conductivity than the resin material.
The resin bottom plate portion has protrusions extending in the axial direction from both side surfaces in the axial direction and provided symmetrically in the axial direction.
The reinforcing material is a hub unit bearing characterized in that the reinforcing material is axially oriented inside the protrusions provided symmetrically in the axial direction.

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