JP2001289257A - Bearing for wheel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bearing for a wheel capable of preventing the intrusion of the water into an engagement part of a seal plate, improving the life of the bearing, solving a problem on the slipping-off and the movement of the seal plate, and easily ensuring the magnetic flux density. SOLUTION: A sealing device 5 is mounted between an inner member 1 and an outer member 2. The sealing device 5 is provided with an elastic member 14 as an encoder lattice on a first seal plate 11. A side lip 16a and radial lips 16b and 16c are integrally mounted on a second seal plate 12. A surface roughness of the engagement part 11aa with the inner member 1, of the first seal plate 11 is controlled to be Rmax 3.0 or less. An interference, a straightness and a circularity of the engagement part 11aa are respectively controlled to be predetermined values. A surface roughness of an engagement part 1b of a counterpart inner member 1 is also controlled to be Rmax 3.0 or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bearing for a wheel in an automobile or the like, and more particularly, to a sealing structure in which an encoder lattice for detecting rotation is integrated.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG.
Inner member 101 and outer member 102 which are rolled through
As a wheel bearing provided with a sealing device 105 between the sealing device 105 and the encoder lattice 106 are integrated (for example, JP-A-6-28101).
No. 8). The sealing device 105 couples the first and second sealing plates 107 and 108 each having an L-shaped cross section to the inner member 101.
And a lip 109 provided on the second seal plate 108. The first seal plate 107 is called a slinger. The encoder lattice 106 is an elastic member mixed with magnetic powder, and is vulcanized and bonded to the first seal plate 107. The encoder grating 106 is formed by alternately forming magnetic poles in the circumferential direction, and is detected by the magnetic sensor 110 disposed in a face-to-face manner.

[0003]

The seal plate 107 serving as a slinger and the inner member 101 serving as a rotating wheel are fitted in a press-fitted state. Have minute irregularities. Therefore, a small amount of water may enter the inside of the bearing from the fitting portion 111.
When such intrusion of water occurs, the sealing plates 107, 10
When rust is generated on the inside of the bearing 8 and the grease penetrates into the inside of the bearing, the internal grease is deteriorated and the life of the bearing is shortened. For example, the surface roughness of the fitting portion is about Rmax 3.4 to 6.3 μm when the seal plate 107 is made of a steel plate, but there is a possibility that water may enter the surface roughness. Therefore, the sealing plate 1
It is considered that a rubber layer is provided in a fitting portion 111 of the inner member 07 with the inner member 101. However, when a thick rubber layer is interposed,
There is a possibility that the fitting force is insufficient, and the seal plate 107 may come off or move into the bearing. In the case where the packing is interposed in the fitting portion 111, the problem of detachment or movement occurs. Instead of interposing an elastic member, it is possible to improve the adhesiveness by making the material of the seal plate 107 itself soft, but such a material is a non-magnetic material, so Function cannot be obtained, and the magnetic flux density is insufficient.

SUMMARY OF THE INVENTION It is an object of the present invention to prevent water from penetrating into a fitting portion of a seal plate, thereby improving the life of the bearing, preventing the seal plate from coming off or moving, and ensuring the magnetic flux density. It is to provide an easy wheel bearing.

[0005]

SUMMARY OF THE INVENTION A wheel bearing according to the present invention comprises an inner member and an outer member, a plurality of rolling elements housed between the inner and outer members, and an annular end portion between the inner and outer members. In a wheel bearing comprising a seal device for sealing a space, the seal device has first and second annular seal plates respectively attached to different ones of the inner member and the outer member. The two seal plates are formed in an L-shaped cross section including a cylindrical portion and an upright plate portion, and face each other. The first seal plate is a member on the rotating side of the inner member and the outer member. The upright portion is disposed on the outer side of the bearing, and an elastic member containing magnetic powder mixed therein is vulcanized and bonded to the upright portion. Is formed, and the second sealing plate is formed of a side lip and a cylinder which are in sliding contact with the standing plate portion. A radial lip slidingly contacting the first seal plate, the cylindrical portion of the second seal plate and the tip of the standing plate portion of the first seal plate facing each other with a slight radial gap, The surface roughness of a fitting portion fitted to the rotating member of the plate is suppressed to Rmax 3.0 or less. According to this configuration, the elastic member mixed with the magnetic powder is vulcanized and bonded to the upright portion of the first seal plate, and the magnetic poles are formed alternately in the circumferential direction. A grating is formed, and rotation can be detected by a magnetic sensor facing the grating. As for the seal between the inner and outer members, the sliding contact of each seal lip provided on the second seal plate and the tip of the upright plate portion of the first seal plate on the cylindrical portion of the second seal plate have a slight radial direction. It is obtained with a labyrinth seal constituted by facing each other with a gap. At the fitting portion between the first seal plate and the member on the rotating side, minute irregularities are formed for surface roughness and shape accuracy, but the surface roughness of this fitting portion is reduced to Rmax 3.0 or less. Due to the suppression, high watertightness can be obtained in this fitting portion. Therefore, it is possible to prevent the grease from being deteriorated due to water entering the bearing, and the bearing life is improved. As described above, in order to cope with the surface roughness of the first seal plate, there is no problem of detachment of the seal plate as in the case where a soft material is interposed.
A material such as a steel plate can be used for the seal plate, and the magnetic flux density of the encoder lattice can be increased.

In the present invention, the first seal plate may be fitted to an outer diameter surface of the inner member. In the case of this configuration, the inner member becomes a rotating wheel.

In the present invention, it is preferable that the interference, straightness, and roundness of the fitting portion of the first seal plate are regulated to predetermined values. These predetermined values are preferably set in the following ranges. Note that straightness refers to the maximum deviation that is parallel to the original geometric straight line.・ The interference should be 40 μm or more.・ The straightness is restricted to 10 μm or less.・ Roundness is regulated to 20 μm or less. The above-mentioned interference is usually about ± 20 μm,
By increasing it to m or more, the sealing property is improved. According to the experiment, the larger the interference, the higher the sealing property tends to be. However, when the surface roughness of the fitting portion is increased to a certain degree or more, the sealing property is limited even if the interference is increased. However, when the surface roughness of the fitting portion was suppressed to Rmax 3.0 or less, satisfactory sealing performance was obtained when the interference was 40 μm or more. For straightness and roundness, the higher the accuracy, the higher the sealing performance.However, if the surface roughness of the fitting part becomes larger than a certain level, even if the straightness or roundness is increased, There was a limit on gender. However, when the surface roughness of the fitting portion is suppressed to Rmax 3.0 or less, satisfactory sealing performance can be obtained by regulating the straightness to 10 μm or less, and the roundness to 20 μm or less. By regulating, satisfactory sealing properties were obtained.

In the present invention, the second seal plate is fitted to a fixed member of the inner member and the outer member, and is fitted to the fixed member of the second seal plate. The part may be coated with a sealant. By coating the sealant in this manner, the watertightness of the fitting portion between the second seal plate and the fixed member is improved. Since the sealant is used as a coating layer, the sealant can be made thin. Therefore, a decrease in the fitting force due to the interposition of the sealant is suppressed, and the second seal plate is prevented from coming off or moving.

In the present invention, the second seal plate is fitted to a fixed member of the inner member and the outer member, and an elastic member is held at the fitting portion of the second seal plate. You may have it. By holding the elastic member in this manner, the watertightness of the fitting portion between the second seal plate and the fixed-side member is improved. The holding of the elastic member may be provided on the entire fitting portion of the second seal plate, or may be provided only on a part thereof, for example, only near the distal end of the cylindrical portion of the second seal plate. In the case where the elastic member is held only in part as described above, a strong fitting force can be obtained at a place where the elastic member is not provided in the fitting portion of the second seal plate.

In the present invention, when the first seal plate is fitted to the outer diameter surface of the inner member, the surface roughness of a fitting portion of the inner member with the first seal plate is reduced. , Rma
It is preferable to keep x3.0 or less. As described above, by suppressing the surface roughness of the inner member to Rmax 3.0 or less, the surface roughness of the seal plate on the mating partner side is reduced to Rmax.
High sealing performance is obtained in combination with the suppression to 3.0 or less.

Also, in the present invention, when the first seal plate is fitted to the outer diameter surface of the inner member, the straightness of the fitting portion of the inner member with the first seal plate is improved. 10
It is preferable to regulate the diameter to not more than μm. In this way, by regulating the straightness of the inner member to 10 μm or less, the surface roughness of the seal plate on the mating side can be reduced to Rmax3.
High sealing performance is obtained in combination with the fact that it is suppressed to 0 or less.

In the present invention, it is preferable that the circumferential runout of the outer surface of the upright portion of the first seal plate is restricted to 0.1 mm or less. The above-described circumferential runout refers to the maximum axial position shift between arbitrary circumferential positions on the outer surface of the standing plate portion. When the upright portion of the first seal plate swings in the circumferential direction, the air gap between the elastic member on which the magnetic pole of the upright portion is formed and the sensor facing the elastic member fluctuates. When the air gap widens in the axial direction, the output pitch difference becomes worse. When the circumferential runout is regulated to 0.1 mm or less, the output pitch difference is almost the same as when the circumferential runout is zero.

[0013]

Embodiments of the present invention will be described with reference to the drawings. As shown in FIG. 1, the wheel bearing includes an inner member 1 and an outer member 2, a plurality of rolling elements 3 housed between the inner and outer members 1 and 2, and an inner member 1 and an outer member 2. And a sealing device 5 for sealing the annular space at the end. The inner member 1 and the outer member 2 are connected to the raceway surfaces 1a, 2 of the rolling element 3.
a, and each track surface 1a, 2a is formed in a groove shape. The inner member 1 and the outer member 2 each include a rolling element 3
Inner and outer members that are rotatable with respect to each other through the bearing. Even if the bearing inner ring and the bearing outer ring are used alone, the bearing inner ring and the bearing outer ring are combined with another component. It may be an assembled member. Further, the inner member 1 may be a shaft. The rolling element 3 is formed of a ball or a roller. In this example, a ball is used.

FIG. 3 shows an example of the overall configuration of the wheel bearing. The wheel bearing is a double row rolling bearing, more specifically, a double row angular contact ball bearing. The bearing inner ring has a hub wheel 6 and a separate body fitted to the end outer diameter of the hub wheel 6. It is composed of the inner ring 1A. A raceway surface of each rolling element row is formed on the hub wheel 6 and the separate inner ring 1A. The separate inner ring 1A serves as the inner member 1 in the example of FIG. One end (for example, an outer ring) of a constant velocity universal joint 7 is connected to the hub wheel 6, and a wheel (not shown) is attached to a hub portion 6 a of the hub wheel 6 with a bolt 8. The other end (for example, the inner ring) of the constant velocity universal joint 7 is connected to the drive shaft. The outer member 2 is
It is composed of a bearing outer ring having a flange 2b and is attached to a housing 10 composed of a knuckle or the like. The outer member 2 is
It has a raceway surface of both rolling element rows. The rolling elements 3 are held by a holder 4 for each row. One end of the annular space between the inner member 1 and the outer member 2, that is, the end on the center side of the axle, is sealed by the sealing device 5. The end of the annular space between the outer member 2 and the hub wheel 6 is sealed with another sealing device 13.

As shown in FIG. 1, the sealing device 5 includes first and second members attached to the inner member 1 and the outer member 2, respectively.
Annular seal plates 11 and 12. These seal plates 11 and 12 are attached to the inner member 1 and the outer member 2 by being fitted in a press-fit state. The two seal plates 11 and 12 are respectively cylindrical portions 11a and 12a and upright plate portions 11
b and 12b are formed in an L-shaped cross section and face each other. The first seal plate 11 is fitted to the inner member 1, which is a member on the rotation side, of the inner member 1 and the outer member 2, and serves as a slinger. Standing plate portion 11b of first seal plate 1
Is disposed on the outer side of the bearing, and an elastic member 14 mixed with magnetic powder is vulcanized and bonded to a side surface on the outer side. This elastic member 14 serves as an encoder lattice,
Magnetic poles N and S (FIG. 2) are formed alternately in the circumferential direction, and are so-called rubber magnets. The magnetic poles N and S are formed so as to have a predetermined pitch p in a pitch circle diameter (PCD). By arranging the magnetic sensor 15 as shown in FIG. 1 so as to face the elastic member 14 serving as the encoder lattice, a rotary encoder for detecting the wheel rotation speed is configured. The elastic member 14 has a tip covering portion 14a that covers the tip inner surface from the tip portion of the standing plate portion 11b of the first seal plate 11.
have. The tip cover 14a may be omitted.

The second seal plate 12 is a first seal plate 1
One side lip 16a slidingly contacting the upright plate portion 11b and radial lips 16b and 16c slidingly contacting the cylindrical portion 11a are integrally provided. These lips 16a to 16c are provided as a part of the elastic member 16 which is vulcanized and bonded to the second seal plate 12. Although the number of these lips 16a to 16c may be arbitrary, in the example of FIG.
6a and two radial lips 16c and 16b located inward and outward in the axial direction. Second seal plate 12
In the figure, an elastic member 16 is held in a fitting portion with the outer member 1 which is a fixed member. That is, the elastic member 1
6 has a tip covering portion 16d that covers from the inner diameter surface of the cylindrical portion 12a to the outer diameter of the tip portion.
6 d is interposed in the fitting portion between the second seal plate 12 and the outer member 1. The tip portion 12aa of the cylindrical portion 12a of the second seal plate 12 is thinner than the other portion of the cylindrical portion 12a and is bent obliquely toward the inside diameter.
The top cover 16d covers aa. Note that the distal end covering portion 16d may be separated from other portions of the elastic member 16.

The cylindrical portion 12a of the second seal plate 12 and the first
Of the sealing plate 11 with a slight radial gap, and the labyrinth seal 1
7. When the end covers 14a, 16d are provided on the elastic members 14, 16 of the first and second seal plates 11, 12, the gap between these end covers 14a, 16d is equal to the gap that constitutes the labyrinth seal 17. Become.

An example of the material of each member will be described. Inner member 1,
Both the outer member 2 and the rolling elements 3 are made of carbon steel such as bearing steel. The first seal plate 11 is made of a magnetic steel plate such as a ferromagnetic material, for example, a ferrite stainless steel plate (J).
For example, SUS430 system of IS standard) or a rust-proofed rolled steel plate is used. As the second seal plate 12, a steel plate, for example, a non-magnetic austenitic stainless steel plate (SUS304 or the like), a rust-proofed rolled steel plate, or the like is used. For example, the first seal plate 11 may be a ferritic stainless steel plate, and the second seal plate 12 may be an austenitic stainless steel plate.

The dimensions and accuracy will be described. The fitting portion 11aa of the first sealing plate 11 fitted to the inner member 1 has a surface roughness of Rmax 3.0 or less. This surface roughness is preferably in the range of Rmax 1.0 to 1.8. The interference, straightness, and roundness of the fitting portion 11aa of the first seal plate 11 are preferably regulated to predetermined values. These predetermined values are preferably set in the following ranges.・ The interference should be 40 μm or more.・ The straightness is restricted to 10 μm or less.・ Roundness is regulated to 20 μm or less.

The surface roughness of the fitting portion 1b of the inner member 1 with the first seal plate 11 is suppressed to Rmax 3.0 or less. The straightness of the fitting portion 1b is restricted to 10 μm or less. The fitting portion 1b is a ground surface. Grinding the raceway surface 1a
And plunge cut for simultaneous grinding. A centerless through-feed system may be used, but if the through-feed system is used, the plunge cut is preferable because the grinding line becomes spiral and dust or the like may enter. The circumferential runout of the outer surface of the upright portion 11b of the first seal plate 11 is preferably restricted to 0.1 mm or less.

According to the wheel bearing of this configuration, the elastic member 14 containing the magnetic powder is vulcanized and bonded to the upright portion 11b of the first seal plate 11, and the magnetic poles N and S are alternately arranged in the circumferential direction.
Is formed, the elastic member 14 forms a so-called encoder lattice, and the magnetic sensor 1 facing the encoder lattice is formed.
5, the rotation can be detected. Regarding the seal between the inner and outer members 1 and 2, the first seal plate 11 is attached to the cylindrical portion 12 a of the second seal plate 12 by sliding contact of the seal lips 16 a to 16 c provided on the second seal plate 12. Standing plate part 1
The labyrinth seal 17 is formed by the front ends of the labyrinth seals 1b facing each other with a slight radial gap.

At the fitting portion between the first seal plate 11 and the inner member 1, minute irregularities are formed for the surface roughness and shape accuracy of the first seal plate 11 and the inner member 1. . However, since the surface roughness of the fitting portion 11aa of the first seal plate 11 is suppressed to Rmax 3.0 or less, the fitting portion 11aa
High water tightness is obtained. Therefore, it is possible to prevent the grease from being deteriorated due to water entering the bearing, and the bearing life is improved. As described above, in order to cope with the surface roughness of the first seal plate 11, there is no problem of detachment of the seal plate 11 when a soft material is interposed, and the first seal plate 11 is made of a steel plate or the like. A material can be used, and the magnetic flux density of the encoder lattice can be increased.

The fitting portion 11a of the first seal plate 11
The interference, straightness, and roundness of “a” are respectively 40 μm or more, straightness is 10 μm or less, and roundness is 2 μm.
Since the thickness is 0 μm or less, the sealing performance of the fitting portion 11aa is further improved. The above-mentioned interference is usually about ± 20 μm, but by increasing it to 40 μm or more, the sealing performance is improved.

According to the experiment, when the interference is 40 μm,
With respect to the case of 110 μm, the air sealing pressure of the fitting portion 11aa when the surface roughness of the fitting portion 11aa was variously changed was obtained. FIG. 4 shows the results. As shown in the drawing, the tighter the interference, the greater the 110 μm, the higher the sealing performance (the higher the air sealing pressure). However, when the surface roughness of the fitting portion 11aa is larger than a certain degree (about Rmax 3.0), there is no large difference in the sealing performance between the case where the interference is large and the case where the interference is small, and the sealing performance by increasing the interference is large. It can be seen that there is a limit to the effect of the improvement. However, when the surface roughness of the fitting portion 11aa was suppressed to Rmax 3.0 or less, high sealing performance was obtained when the interference was 40 μm or more. In particular, in the case of Rmax 1.0 to 1.8, high sealing performance is obtained when the interference is large, and when the interference is 110 μm in the surface roughness in this range, the air sealing pressure is 1.5 kgf /.
It is understood that a high sealing property can be obtained when the density is about ² cm ² or more.

As for the straightness and roundness of the fitting portion 11aa, the sealing performance tends to be higher as the precision is higher. However, when the surface roughness of the fitting portion 11aa is larger than a certain level, the straightness and the straightness are reduced. Even if the roundness was increased, there was a limit in the sealing performance. However, the surface roughness of the fitting portion 11aa is reduced to Rmax.
When the straightness is suppressed to 3.0 or less, satisfactory sealing performance can be obtained by regulating the straightness to 10 μm or less as seen from FIG. 5, and the circularity is 20 μm as seen from FIG. Satisfactory sealing properties were obtained by restricting to the following.

If the surface roughness of the fitting portion 1b of the inner member 1 with the first seal plate 11 is suppressed to Rmax 3.0 or less, the surface roughness of the sealing plate 11 on the mating side is set. R
High sealing performance is obtained in combination with the fact that max is not more than 3.0. When the straightness of the fitting portion 1b is restricted to 10 μm or less, higher sealing performance can be obtained. When the fitting surface 1b of the inner member 1 is formed as a grinding surface by plunge cutting, the raceway surface 1a and the fitting surface 1b can be formed by simultaneous grinding, thereby preventing the misalignment of the two. In the case of the plunge cut, the surface roughness of the fitting surface 1b is set to Rmax3.
It is easy to make the processing to be 0 or less, and by further improving the surface roughness accuracy, it is possible to further improve the sealing performance.

As for the fitting portion between the second seal plate 12 and the outer member 2, the elastic member 16 is held by the second seal plate 2, that is, since the distal end covering portion 16 d is provided, this elastic member 16 improves the sealing performance. Since the front end cover portion 16d is only a part of the fitting portion of the second seal plate 12 with the outer member 1, the remaining portion of the second seal plate 12 can be strongly fitted to the outer member 1, Dropout and movement are prevented.

Instead of providing the tip covering portion 16d, the fitting portion of the second seal plate 12 with the outer member 2 may be coated with a sealant 18 as shown in FIG. By coating the sealant 18 in this manner, the watertightness of the fitting portion between the second seal plate 12 and the outer member 2 is improved. Since the sealant 18 is used as a coating layer, it can be made thin.
The reduction of the fitting force due to the presence of is prevented, and the second seal plate 12 is prevented from coming off or moving.

Further, since the circumferential runout of the outer surface of the upright portion 11b of the first seal plate 11 is regulated to 0.1 mm or less, the encoder constituted by the encoder grid formed by the elastic member 14 and the sensor 15 is not provided. And the output pitch difference is excellent. FIG. 6 shows the relationship between the sensor 15 and the elastic member 14 serving as an encoder grid.
When the upright plate portion 11b of the seal plate 11 of the first embodiment swings in the circumferential direction, the elastic member 1 having the magnetic poles of the upright plate portion 11b is formed.
The air gap G (FIG. 7) between the sensor 4 and the sensor 15 facing the sensor 4 fluctuates. When the air gap G expands in the axial direction,
The output pitch difference becomes worse. For this reason, as can be seen from FIG. 6, it is preferable to restrict the circumferential runout to 0.1 mm or less, which results in the same output pitch difference as when the circumferential runout is zero. ± 1% pitch difference
(2% in range)
mm or less. It should be noted that the output pitch difference means the sensor 15 when the elastic member 14 is rotated once.
The pitch of the one-rotation output waveform (compression waveform) obtained in step (1) is measured, and the maximum deviation from the target point is referred to.

[0030]

According to the wheel bearing of the present invention, the surface roughness of the fitting portion of the first seal plate provided with the elastic member serving as the encoder lattice with the rotating side member is suppressed to Rmax 3.0 or less. Water can be prevented from entering the fitting portion of the seal plate, and the life of the bearing can be improved. Further, there is no problem that the seal plate comes off or moves, and it is easy to secure the magnetic flux density.

[Brief description of the drawings]

FIG. 1 is a partial sectional view of a wheel bearing according to an embodiment of the present invention.

FIG. 2 is a partial front view of an elastic member serving as the encoder lattice.

FIG. 3 is a sectional view of an overall example of the wheel bearing.

FIG. 4 is a graph showing the relationship between the inner diameter surface roughness of the seal plate and the air sealing pressure in a plurality of types of interference.

FIG. 5 is a graph showing the relationship between the straightness of the inner diameter of the seal plate and the air sealing pressure.

FIG. 6 is a graph showing the relationship between the roundness of the inner diameter of the seal plate and the air sealing pressure.

FIG. 7 is an explanatory diagram of an air gap.

FIG. 8 is a graph showing the relationship between shake and pitch difference.

FIG. 9 is a partial cross-sectional view of a wheel bearing according to another embodiment of the present invention.

FIG. 10 is a sectional view of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Inner member 1b ... Fitting part 2 ... Outer member 3 ... Rolling element 5 ... Sealing device 11 ... First seal plate 12 ... Second seal plate 11a, 12a ... Cylindrical portion 11b, 12b ... Standing plate portion 11aa ... fitting part 14 ... elastic member 15 ... sensor 16 ... elastic member 18 ... sealant N, S ... magnetic pole

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F16C 33/80 F16C 33/80 F16J 15/32 311 F16J 15/32 311P F-term (Reference) 3J006 AE23 AE37 3J016 AA01 AA02 BB03 BB17 CA02 CA03 CA06 3J101 AA01 AA52 AA62 BA56 DA20 EA02 EA74 EA77 FA04 FA08 GA03

Claims (11)

[Claims] 1. A wheel bearing comprising an inner member and an outer member, a plurality of rolling elements housed between the inner and outer members, and a seal device for sealing an end annular space between the inner and outer members. In the above, the sealing device has first and second annular seal plates respectively attached to different ones of the inner member and the outer member, and both seal plates are respectively formed with a cylindrical portion. A plate portion is formed in an L-shaped cross section and faces each other.
The seal plate is fitted to the rotating member of the inner member and the outer member, the upright portion is disposed on the outer side of the bearing, and the magnetic powder is mixed in the upright portion. The elastic member is vulcanized and bonded, and the elastic member is alternately formed with magnetic poles in the circumferential direction. The second seal plate integrally includes a side lip slidingly contacting the upright plate portion and a radial lip slidingly contacting the cylindrical portion. The cylindrical portion of the second seal plate and the tip of the upright portion of the first seal plate face each other with a slight radial gap, and are fitted to the rotating side member of the first seal plate. A bearing for a wheel, characterized in that the surface roughness of the mating fitting portion is suppressed to Rmax 3.0 or less. 2. The wheel bearing according to claim 1, wherein the first seal plate is fitted on an outer diameter surface of the inner member. 3. The wheel bearing according to claim 1, wherein the interference, the straightness, and the roundness of the fitting portion of the first seal plate are regulated to predetermined values, respectively. 4. The wheel bearing according to claim 3, wherein the interference of the fitting portion of the first seal plate is 40 μm or more. 5. The wheel bearing according to claim 3, wherein the straightness of the fitting portion of the first seal plate is restricted to 10 μm or less. 6. The wheel bearing according to claim 3, wherein the roundness of the fitting portion of the first seal plate is restricted to 20 μm or less. 7. The second seal plate is fitted to a fixed member of the inner member and the outer member, and the second seal plate is fitted to the second member.
The wheel bearing according to any one of claims 1 to 6, wherein a fitting portion of the seal plate with the fixed side member is coated with a sealant. 8. The second seal plate is fitted to a fixed member of the inner member and the outer member, and
The wheel bearing according to any one of claims 1 to 6, wherein an elastic member is held in a fitting portion of the seal plate with the fixed member. 9. The fitting of the first seal plate to the outer diameter surface of the inner member, and the surface roughness of the fitting portion of the inner member with the first seal plate is reduced to Rmax 3.0. The wheel bearing according to any one of claims 2 to 8, wherein the bearing is suppressed as follows. 10. The first seal plate is fitted to the outer diameter surface of the inner member, and the straightness of the fitting portion of the inner member with the first seal plate is restricted to 10 μm or less. A wheel bearing according to any one of claims 2 to 8. 11. The wheel bearing according to claim 1, wherein the circumferential runout of the outer surface of the upright portion of the first seal plate is restricted to 0.1 mm or less.