WO2003072973A1

WO2003072973A1 - Bearing unit for wheels

Info

Publication number: WO2003072973A1
Application number: PCT/JP2003/002148
Authority: WO
Inventors: Junshi Sakamoto
Original assignee: Nsk Ltd.
Priority date: 2002-02-28
Filing date: 2003-02-26
Publication date: 2003-09-04
Also published as: AU2003211730A1; JP2005256847A

Abstract

An attaching flange (13) is formed with a plurality of circumferentially-spaced attaching holes (15). The portions around the open edges of these attaching holes (15) are each formed with a recess (38) over the entire open edge of the attaching hole (15) such that the recess is depressed from the attaching surface (14) and is coaxial with the attaching hole (15). Let D be the inner diameter of the recess (38) and d be the inner diameter of the attaching hole (15), and D=d+(5-40 mm). This arrangement prevents deformation, which attends the pressure fitting of a stud (9) into the attaching hole (15), from reaching the attaching surface (14), thus suppressing deflection of a rotor (2) fixed on the attaching surface (14) of an attaching flange (13), thereby suppressing judder that tends to occur during braking.

Description

Description Wheel bearing unit Technical field

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a wheel bearing unit for supporting a wheel of a motor vehicle and a braking rotary body such as a rotor or a drum. Background art

A wheel 1 constituting a wheel of an automobile and a rotor 2 constituting a disc brake which is a braking device constitute a suspension device, for example, with a structure as shown in FIG. 1 showing a first embodiment of the present invention. The knuckle 3 is rotatably supported. That is, the outer ring 6, which is a stationary side member that does not rotate during use, constituting the wheel bearing unit 5 is fixed to the circular support hole 4 formed in the knuckle 3 by a plurality of ports 7. . On the other hand, the wheel 1 and the rotor 2 are fixedly connected to a hub 8, which is a rotating member rotating during use, constituting the wheel bearing unit 5 by a plurality of studs 9 and nuts 10. .

On the inner peripheral surface of the outer ring 6, double-row outer ring races 11a and lib, each of which is a stationary raceway, are formed, and a coupling flange 12 is formed at an intermediate portion of the outer peripheral surface. The outer ring 6 is fixed to the knuckle 3 by connecting the connecting flange 12 to the knuckle 3 with the bolts 7. On the other hand, a part of the outer peripheral surface of the hub 8 is an outer end opening of the outer ring 6 (the term "outside in the axial direction" means a part that is outward in the width direction when assembled to an automobile, except for Fig. 3). On the left side of each figure, on the other hand, the right side of each figure except for Figure 3, which is the center in the width direction when assembled to a car, is called the inner side in the axial direction. 3 is formed.

The wheel 1 and the rope 2 are connected and fixed to a mounting surface 14 provided on one side surface (outside surface in the illustrated example) of the mounting flange 13. For this reason, at a plurality of locations in the circumferential direction of the mounting flange 13, the center axis is the center axis of the hub 8. Each has a mounting hole 15 penetrating both sides of the mounting flange 13. Further, a serration portion 16 is provided on the outer peripheral surface of the base end portion (right end portion in FIG. 1) of each of the studs 9, and a male screw portion 17 is provided on the outer peripheral surface of the first half portion (left half portion in FIG. 1). 2, 4 and 5) respectively. Then, the serration portion 16 of each stud 9 is press-fitted into each of the mounting holes 15 so that the base end of each of the studs 9 is mounted on the mounting flange 13 and the mounting flange 13 is fixed to the mounting flange 13. It is fixed with rotation stopped.

The mouth 2 is overlaid on the mounting surface 14, and the wheel 1 is overlaid on one side of the mouth 2. In this state, the leading ends of the respective slides 9 pass through through holes 18 and 19 provided in the wheel 1 and the rotor 2, respectively, and project from one side surface of the wheel 1. The nut 10 is screwed into a male thread portion 17 provided at the tip of the stud 9 protruding from one side surface of the wheel 1, and further tightened. With this configuration, the wheel 1 and the connector 2 are connected and fixed to the mounting surface 14 of the mounting flange 13.

The hub 8 is formed by combining a hub body 20 and an inner ring 21. On the outer peripheral surface of the intermediate portion of the hub body 20 among these, the portion facing the outer outer raceway 11a of the double-row outer raceway 1 la and lib is the first inner race which is the rotation side raceway. The track 22 is formed directly on the hub body 20. Further, the inner ring 21 is externally fitted and fixed to a small-diameter stepped portion 23 formed on the outer peripheral surface of the inner end portion of the hub body 20 to constitute the hub 8. The second inner raceway 24, which is also a rotating raceway, formed on the outer peripheral surface of the inner raceway 21 is replaced with the inner outer raceway raceway 11 1 of the double row outer raceway races 11 a and 11 b. b. In the case of the example shown in the figure, the inner end of the inner ring 21 is held down by a caulking portion 25 formed by plastically deforming the inner end of the hub body 20 radially outward. It is fixed to the hub body 20.

A plurality of balls 26, 26, each of which is a rolling element, is provided between each of the outer raceways 11a, 11b and the first and second inner raceways 22, 24. It is provided so that it can roll freely while being held by the retainers 27 and 27, respectively. With this configuration, a double-row angular contact type ball bearing that is a combination of rear surfaces is formed, and the hub 8 is rotatably supported inside the outer ring 6 and rotatably supports a radial load and a thrust load. are doing. The seal rings 28 a and 28 b are provided between the inner peripheral surfaces of both ends of the outer ring 6, the outer peripheral surface of the middle portion of the outer ring 8 and the outer peripheral surface of the inner end of the inner ring 21. Is provided to block the internal space in which the balls 26 and 26 are provided from the outside. Further, the illustrated example is a wheel bearing unit 5 for driving wheels (rear wheel of a shaku wheel and! ^ Shaku wheel, front wheel of an FF vehicle, and all wheels of a 4WD vehicle). A spline hole 29 is formed in the center. The spline shaft 31 attached to the constant velocity joint 30 is inserted into the spline hole 29.

When using the rolling bearing unit 5 for a wheel as described above, as shown in FIG. 1, the outer ring 6 is fixed to the knuckle 3, and the wheel 1 in which the mounting flange 13 of the hub 8 is combined with a not-shown screwer 1. And the rotor 2 which is a rotating body for braking is fixed. A disc brake for braking is constructed by combining the mouth 2 of the above and a support and a caliper (not shown) fixed to the knuckle 3. At the time of braking, a pair of pads provided across the mouth 2 is pressed against both side surfaces of the rotor 2 which are friction surfaces for braking. In the present specification, the braking friction surface means both sides in the axial direction of the rotor when the rotating body for braking is a mouth, and when the rotating body for braking is a drum, It refers to the inner peripheral surface of this drum.

By the way, it is known that vibrations with unpleasant noise, often called judder, occur when braking a car. There are various known causes of such vibration, such as uneven friction between the side surface of the rotor 2 and the pad lining, but the above-mentioned runout of the rotor 2 can also be a major cause. Are known. In other words, the side of the mouth and mouth 2 should be at right angles to the rotation center of the mouth and mouth 2, but it is difficult to make it completely at right angles due to unavoidable manufacturing errors. As a result, it is inevitable that the side surface of the road 2 swings in the direction of the rotation axis (the left and right direction in FIG. 1) when the vehicle is traveling.

When such a runout (the amount of displacement in the left-right direction in FIG. 1) increases, the judder occurs when the lining of a pair of pads is pressed against both side surfaces of the rotor 2 for braking. If the drum constituting the drum brake is fixed to the side surface of the mounting flange 13 and the inner peripheral surface of the drum is not completely parallel to the rotation center of the drum, the inner peripheral surface of the drum is changed to the inner peripheral surface. When pressed against the surface, it still looks like Jada Vibration occurs. In order to suppress the judder caused by such a cause, the rotor

It is important to suppress (improve) the axial runout (axial runout) of the side surface 2 or the radial runout of the inner peripheral surface of the drum.

However, in the case of the conventional wheel bearing unit, the vibration of the braking friction surface (the side surface of the opening 2 or the inner peripheral surface of the drum) of the braking rotating body as described above is likely to occur for the following reasons. there is a possibility.

First, in the case of the so-called third-generation wheel bearing unit 5 in which the first inner raceway 22 is directly formed on the outer peripheral surface of the intermediate portion of the hub 8 as shown in FIG. It is troublesome to secure the parallelism of the inner ring tracks 22 and 24. That is, in the case of a so-called second-generation wheel bearing unit in which a pair of inner rings are externally fitted and fixed to the hub body, a wide small-diameter step formed on the hub body to externally fit the pair of inner rings. The outer peripheral surface is a single cylindrical surface whose diameter does not change over substantially the entire length of the portion where these inner rings are fitted. Such a single cylindrical surface is relatively easy to machine, and therefore, by externally fitting a pair of inner rings having the same diameter to the small-diameter step portion, the first and second outer surfaces are formed on the outer peripheral surface of the hub. When the inner ring raceways are provided, if the accuracy of the pair of inner races can be ensured, it is easy to ensure the parallelism of the two inner raceways with respect to the rotation center.

On the other hand, in the case of the third-generation wheel bearing unit described above, a portion in which the first inner raceway 22 is formed at the axially intermediate portion of the hub body 20 and a second inner raceway 24 The small-diameter stepped portion 23 for fixing the inner ring 21 provided with the outer ring to the outside fits into a stepped shape. Accordingly, compared to the second-generation wheel bearing unit small, the braking friction surface of the braking rotary body based on the deterioration of the parallelism of the first and second inner ring raceways 22 and 24 is reduced. Deflection may easily occur.

Also, as shown in Fig. 1 above, the inner end surface of the inner ring 21 is held down by a caulking portion 25 formed by plastically deforming the inner end portion of the hub body 20 radially outward. In the case of the structure of fixing the hub body 20 to the hub body 20, the mounting flange 13 may be slightly deformed depending on the method of fixing the hub body 20 when forming the caulked portion 25. That is, when the caulking portion 25 is formed, a large load is applied to the inner end of the hub body 20 so that the inner end is plastically deformed while the mounting flange 13 is supported and fixed. And provided on one side of the mounting flange 13 based on this load. The mounting surface 14 may be slightly deformed. As a result, there is a possibility that the braking friction surface of the braking rotator, which is superimposed on and fixed to the mounting surface 14, is likely to swing.

Further, in the case of the structure as shown in FIG. 1 described above, a plurality of studs 9 for supporting the rotating body for braking are press-fitted and fixed to the mounting holes 15 provided in the mounting flange 13. Therefore, along with the press-fitting, a part of the mounting surface 14 around the opening edge of each of the mounting holes 15 and the inner peripheral surface of the mounting hole 15 and the selection of the screw 9 Due to the engagement with the one-part part 16, there is a possibility that the part slightly protrudes in a direction that is convex with respect to the mounting surface 14. In particular, when the amount of protrusion around the opening edge of each of the mounting holes 15 is different for each of the mounting holes 15, the above-described braking rotation, which is combined and fixed in a state of being superposed on the mounting surface 14. It is not preferable because the friction surface for braking of the body easily swings.

As described above, when the first inner raceway 22 is formed directly on the hub body 20 and the caulking portion 25 is formed at the inner end of the hub body 20, the braking rotor Therefore, it is particularly important to suppress the vibration of the braking friction surface due to the press-fitting of the stud 9 as described above.

In view of such circumstances, the wheel bearing unit of the present invention has a structure capable of preventing the vibration of the friction surface for braking based on the press-fit of the stud, and further, the generation of judder due to the vibration of the friction surface for braking. It was invented in order to realize. Disclosure of the invention

According to one aspect, a wheel bearing unit of the present invention has a stationary-side track that has a stationary-side track and does not rotate during use, a rotating-side member that has a rotating-side track and rotates during use, A mounting flange provided on the outer peripheral surface of the rotating member, a plurality of mounting holes formed so as to penetrate the mounting flange in the axial direction, and press-fitting a base end of each mounting hole into each of the mounting holes. A plurality of studs fixed to the mounting flange; and a plurality of rolling elements provided between the stationary-side raceway and the rotating-side raceway. The nut for rotation is joined to and fixed to the mounting surface provided on one side of the mounting flange by a nut screwed onto the evening pad. Hole opening 緣 around A recess is provided around the entire opening edge of the mounting hole in a state of being recessed from the mounting surface. When the inner diameter of the recess is D and the inner diameter of the mounting hole is d, D = d + (5 to 40 mm).

According to another aspect, a wheel bearing unit of the present invention has a stationary row member that has multiple rows of stationary tracks and does not rotate during use, and has a double row of rotating tracks that are rotated during use. A rotating side member, a mounting flange provided on an outer peripheral surface of the rotating side member, a plurality of mounting holes formed so as to penetrate the mounting flange in the axial direction, and a base formed in each of the mounting holes. It is provided with a plurality of studs fixed to the mounting flange by press-fitting the ends, and a plurality of rolling elements respectively provided between the stationary-side orbits and the rotating-side orbits.

One of the stationary-side member and the rotating-side member located radially inward is the stationary-side or rotating-side track formed directly at an axially intermediate portion of the outer peripheral surface. An inner ring raceway, a small-diameter step formed at one end in the axial direction of the outer peripheral surface, and an inner ring externally fitted and fixed to the small-diameter step are provided. The inner race has a second inner raceway, which is the stationary raceway or the rotation raceway, formed on an outer peripheral surface thereof, and a caulking portion formed by plastically deforming one end of the one member radially outward. Thus, one end face is suppressed.

In use, the rotating body for braking is connected and fixed to the mounting surface provided on one side of the mounting flange by the studs and nuts screwed to the studs.

In particular, in the wheel bearing unit of the present invention, a recess is formed in a part of the mounting surface around the opening edge of each of the mounting holes, and the mounting hole and the mounting hole are recessed from the mounting surface. The mounting hole is provided concentrically around the entire opening edge of the mounting hole. When the inner diameter of the recess is D and the inner diameter of the mounting hole is d, it is preferable that D = d + (5 to 40 MI).

According to the wheel bearing unit of the present invention configured as described above, judder can be less likely to occur during braking. That is, at the time of press-fitting of each stud, based on the engagement between the outer peripheral surface of each stud and the inner peripheral surface of each mounting hole, the periphery of the opening edge of each mounting hole is convex with respect to the mounting surface. In the direction of It occurs in a recess provided in the part. For this reason, the mounting surface can be prevented from being deformed due to the protrusion, and the braking friction surface of the braking rotating body that is fixed by being superimposed on the mounting surface is less likely to swing. In addition, even when the amount of protrusion differs for each of the mounting holes, since such protrusion occurs in each of the concave portions as described above, the braking rotator based on the difference in the amount of protrusion is used for braking. Deflection of the friction surface can also be suppressed. As a result, the above-mentioned judder due to the run-out of the friction surface for braking can be hardly generated.

When the inner diameter of the recess is D and the inner diameter of the mounting hole is d, D = d + (5 to 40 inm), so that the deformation of the mounting surface due to the protrusion as described above The contact area between the mounting surface and the rotating body for braking can be ensured while suppressing, and the rotating body for braking can be supported stably (without rattling). When the inner diameter D of the recess is less than d + 5 mm (D <d + 5 mm), the deformation of the mounting surface due to the press-fitting of the stud causes the braking friction surface of the braking rotating body to deform. As the run-out increases, the above-mentioned judder easily occurs. On the other hand, when the inner diameter D of the concave portion exceeds d + 40 mm (D> d + 40 mm), it becomes difficult to secure a contact area between the mounting surface and the braking rotating body. In particular, when the nut screwed to the stud is tightened, the deformation of the braking rotator becomes large, and the support of the braking rotator becomes unstable (rattle is likely to occur). As a result, the vibration of the braking friction surface of the braking rotator becomes large, so that the judder easily occurs.

The following table shows the results of experiments conducted by the present inventor to determine the relationship between the size of the inner diameter D of the recess and the occurrence of judder using a wheel bearing unit as shown in FIG. Is shown.

[table 1 ]

In Table 1, “〇” indicates that almost no judder occurred, and “X” indicates that judder occurred so much that it became a problem. As is evident from the description in Table 1, if the inner diameter D of the concave portion is set to be equal to or larger than the inner diameter d of the mounting hole + 5 thighs (D≥d + 5 mm), the occurrence of judder can be suppressed. In other words, it can be seen that the deformation around the aperture of each of the mounting holes due to the press-fitting of the studs does not extend more than 2.5 s from the opening edge of each of the mounting holes. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a sectional view showing a first example of an embodiment of the present invention in a state where a wheel and a mouth are attached.

FIG. 2 is an enlarged sectional view corresponding to a portion A in FIG. FIG. 3 is a view of the hub body taken out from the left side of FIG. 1.

FIG. 4 is a sectional view showing a second example of the embodiment of the present invention.

FIG. 5 is a sectional view showing a third example of the embodiment of the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

1 to 3 show a first example of an embodiment of the present invention. The feature of the present invention is that the mounting surface 14 which is one side surface of the mounting flange 13 provided on the outer peripheral surface of the hub 8 which is a rotating side member has a sufficient surface accuracy. The point is that the swing of the mouth 2 which is the rotating body for braking that is connected and fixed to 4 is suppressed. The basic configuration and operation of the other wheel bearing unit 5 are as described above with reference to FIG. 1 in the section of [Prior Art], and therefore, duplicate description will be omitted or simplified. Hereinafter, the description will be made focusing on the characteristic portions of the present invention.

On the outer peripheral surface of the hub body 20 constituting the hub 8, a wheel 1 constituting a wheel and a mounting flange 13 for fixing the rotor 2 which is a rotating body for braking are provided. At a plurality of locations in the circumferential direction of the mounting flange 13, a plurality of (five in this example) mounting holes 15, 15 are provided on the same circumference centered on the rotation center of the hub 8. Are formed at equal intervals, and the base end of the stud 9 is press-fitted and fixed to each of the mounting holes 15. Each of these studs 9 has an outward flange-shaped flange 32 on the base end surface, a selection portion 16 on a portion near the base end of the outer peripheral surface, and a male screw portion for fixing a nut 10 on the first half similarly. 17 are formed respectively.

In particular, in the case of this example, recesses 38, 38 are formed around the opening edges of the mounting holes 15 and 15 in a part of the mounting surface 14 in the axial direction from the mounting surface 14. In the recessed state, they are provided concentrically with the mounting holes 15 and 15 over the entire periphery of the opening edges of the mounting holes 15 and 15. When the inner diameter of each of the recesses 38, 38 is D, and the inner diameter of each of the mounting holes 15, 15 is d, D = d + (5 to 40 mm). The depth h in the axial direction of each of the recesses 38, 38 is equal to or greater than the deformation amount (0.1 to 0.2 band) of the mounting surface 14 due to the press-fitting of the studs 9. However, it is enough to provide about 0.5 strokes (0.2 ≤ h ≤ h ≤ 0.5 mm). If the depth h of each of the recesses 38, 38 is suppressed to a maximum of about 0.5 mm, the depth of each of the recesses 38, 38 can be reduced. The decrease in the strength of the mounting flange 13 due to the formation is almost negligible.

According to the wheel bearing unit of the present embodiment configured as described above, judder can be hardly generated during braking. That is, when the above-mentioned studs 9 are press-fitted, based on the engagement between the outer peripheral surface of each of the studs 9 and the inner peripheral surface of each of the mounting holes 15, 15, the respective mounting holes 15, 15 are formed. Even when the periphery of the opening edge protrudes in a direction protruding with respect to the mounting surface 14, this projection occurs in the recesses 38, 38 provided around the opening edge. For this reason, the mounting surface 14 can be prevented from being deformed due to the protrusion, and the braking friction surface (the side surface of the opening 2 or (The inner peripheral surface of the drum) is less likely to oscillate. Moreover, even when the amount of protrusion differs for each of the mounting holes 15 and 15, since such protrusion occurs in each of the recesses 38 and 38 as described above, the difference in the amount of protrusion Therefore, the vibration of the friction surface for braking of the rotating body for braking can be suppressed. As a result, it is possible to make it difficult to generate the above-mentioned judder due to the vibration of the friction surface for braking.

Further, when the inner diameter of each of the recesses 38, 38 is D, and the inner diameter of the mounting holes 15, 15 is d, D = d + (5 to 40 dust). While suppressing the deformation of the mounting surface 14 due to such protrusions, the contact area between the mounting surface 14 and the rotating body for braking is secured, and the rotating body for braking is stabilized (without rattling). I can support it. When the inner diameter D of each of the recesses 38, 38 is less than d + 5 mm (D <d + 5 mm), the above-described braking is caused by the deformation of the mounting surface 14 due to the press-fitting of the stud 9. The above-mentioned judder is more likely to occur when the vibration of the friction surface for braking of the rotating body becomes large. On the other hand, when the inner diameter D of each of the recesses 38, 38 exceeds d + 40 (D> d + 40), a contact area between the mounting surface 14 and the rotating body for braking is secured. If it becomes difficult to support, the support of the rotating body for control becomes unstable (rattle is likely to occur). As a result, the vibration of the braking friction surface of the braking rotating body becomes large, and the above-mentioned judder easily occurs. In the case of this example, the stud 9 is press-fitted and fixed to the mounting hole 15 by engaging the outer peripheral surface of the serration portion 16 provided on the stud 9 with the mounting hole 15. It is not limited to such a structure. For example, the stud and the mounting hole may be press-fitted and fixed only by interference fit, or the mounting hole may be made non-circular, and the part of the outer peripheral surface of the stud that matches the inner peripheral surface of the mounting hole may be the same. The non-circular portions may be press-fitted and fixed to each other by interference fit. In short, the present invention can be applied to any structure as long as the stud is press-fitted and fixed in the mounting hole to prevent co-rotation even when tightening the nut.

Next, FIG. 4 shows a second example of the embodiment of the present invention. In the case of the first example described above, the seal ring 28 b (FIG. 1) is provided between the inner peripheral surface of the inner end of the outer ring 6 and the outer peripheral surface of the inner end of the inner ring 21, whereas In the case of the example, an encoder 33 constituting a rotation speed detecting device is provided between the inner peripheral surface of the inner end of the outer race 6 and the outer peripheral surface of the inner end of the inner race 21. That is, in the case of the present example, the encoders 33 are externally fitted and fixed to the outer peripheral surface of the inner end portion of the inner ring 21 by interference fitting. In this encoder 33, an encoder body 35, which is a rubber magnet mixed with ferrite powder or rare earth magnet powder, is attached to the inner surface of a core metal 34 having an L-shaped cross section over the entire circumference. Become. The encoder main body 35 is magnetized in the axial direction, and the magnetization directions are alternately changed at equal intervals in the circumferential direction. Therefore, S poles and N poles are alternately arranged at equal intervals in the circumferential direction on the inner side surface in the axial direction of the encoder 33.

Then, the N pole and the S pole of the rubber magnet constituting the encoder body 35 are alternately arranged in the vicinity of the detection surface of a rotation detection sensor (not shown) which is opposed to the encoder body 35 via a minute gap. When passing, the density of the magnetic flux flowing in the rotation detection sensor changes, and the output of the rotation detection sensor changes. The frequency at which this output changes is proportional to the rotational speed of the wheels. If this output signal is sent to a controller (not shown), the antilock brake system (ABS) and the traction control system (TCS) can be properly controlled. it can. Other configurations and operations are the same as those in the first example described above.

Next, FIG. 5 shows a third example of the embodiment of the present invention. The first example described above and the second example described above have a structure for supporting the driving wheels (the rear wheel of the car and the shaku1 car, the front wheel of the FF car, and the front wheel of the 4WD car), and are also used during use. The stationary side member that does not rotate is referred to as an outer ring 6, and a structure is shown in which a rotary member 8 that is a rotating side member that rotates during use is provided inside the outer ring 6 in the radial direction. On the other hand, in the case of this example, the support shaft is configured to support the driven wheels (the front wheels of the FR and RR vehicles, the rear wheels of the FF vehicle), and the stationary shaft is located on the inner diameter side. 3 and turning the support shaft 36 radially outward. This shows a structure provided with a hub 8a as a transfer-side member. That is, in the case of the present example, the first and second inner ring raceways 22 each of which is a stationary side raceway are mounted on the support shaft 36 which can be freely fixed to the end of an axle (not shown) constituting the suspension system. , 24 are provided. The first inner ring gauge 22 is formed directly on the outer peripheral surface of the intermediate portion of the support shaft 36. At the same time, an inner ring 21 a having the second inner raceway 24 formed on the outer peripheral surface is fixed to the small diameter step 23 a formed on the outer peripheral surface of the outer end of the support shaft 36. are doing. The outer end surface of the inner race 21a is suppressed by a caulking portion 25a formed by plastically deforming the outer end of the support shaft 36 radially outward.

On the other hand, the hub 8a, which is a rotating member, is provided radially outward of the support shaft 36. The inner peripheral surface of the hub 8a is formed with double-row outer raceways 11a and 11b, each of which is a rotating raceway, and the outer peripheral surface is formed with a mounting flange 13 respectively. The wheels 1 that make up the wheels are mounted on the mounting surface 14 of the mounting flange 13 above, together with the rotor 2 (see Fig. 1) that forms the braking device. A stud 9 press-fitted into 5 and a nut 10 (see FIG. 1) screwed into this thread 9 are connected and fixed. A plurality of balls 26, 26 each of which is a rolling element is provided between each of the outer raceways 11a, 11 and the first and second inner raceways 22, 24. However, they are provided independently of rolling while held by retainers 27 and 27, respectively. In addition, the outer end opening of the hub 8a is closed with a cap 37, and a seal ring 28a is provided between the inner peripheral surface of the inner end of the hub 8a and the intermediate outer peripheral surface of the support shaft 36. To prevent foreign matter from entering the space in which the balls 26 and 26 are provided. Other configurations and operations are the same as those in the first and second examples described above. Industrial applicability

Since the wheel bearing unit of the present invention is configured and operates as described above, it is possible to sufficiently suppress unpleasant noise and vibration generated during braking.

Claims

The scope of the claims

1. A stationary member that has a stationary track and does not rotate during use, a rotating member that has a rotating track and rotates during use, and a mounting flange provided on the outer peripheral surface of the rotating member. A plurality of mounting holes formed so as to penetrate the mounting flange in the axial direction, and a plurality of studs fixed to the mounting flange by press-fitting the respective base ends into these mounting holes. A plurality of rolling elements provided between the stationary side track and the rotating side track;

At the time of use, a wheel bearing unit for fixing the thread in such a manner that the braking rotary body is overlapped with the mounting surface provided on one side of the mounting flange by the above-mentioned stats and the nuts screwed to the respective slides. In the bird

A recess is provided around the opening edge of each of the mounting holes in a part of the mounting surface and is recessed from the mounting surface over the entire periphery of the opening edge of the mounting hole. To

A bearing unit for a wheel, wherein D is D, and D is d + (5 to 40 mm), where D is the inner diameter of the mounting hole.

2. A stationary member that has multiple rows of stationary tracks and does not rotate during use, a rotating member that has multiple rows of rotating tracks and rotates during use, and an outer circumferential surface of the rotating member Mounting flange, a plurality of mounting holes formed in a state penetrating the mounting flange in the axial direction, and a plurality of mounting holes fixed to the mounting flange by press-fitting respective base ends into the mounting holes. A plurality of rolling elements provided between each of the stationary-side tracks and the respective rotating-side tracks.

One of the stationary-side member and the rotating-side member, which is located radially inward, is the stationary-side or rotating-side track formed directly on the axially intermediate portion of the outer peripheral surface. An inner ring raceway, a small-diameter step formed at one end in the axial direction of the outer peripheral surface, and an inner race fixed to the small-diameter step externally fit to the inner race. Alternatively, a second inner raceway which is a rotation side raceway is formed, and one end of the one member is plastically deformed radially outward, and one end surface thereof is suppressed by a caulking portion,

At the time of use, brake by the above studs and nuts screwed to each stud In the wheel bearing unit, the rotating body for the wheel is joined and fixed in a state of being superimposed on the mounting surface provided on one side of the mounting flange,

A recess is formed in a part of the mounting surface around the opening edge of each of the mounting holes, and is substantially concentric with the mounting hole while being recessed from the mounting surface, over the entire periphery of the opening edge of the mounting hole. A bearing unit for a wheel, wherein D = d + (5 to 40 mm), where D is the inner diameter of the recess and d is the inner diameter of the mounting hole.