JP2002340919A - Rotational speed detector and bearing for wheel having the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotational speed detector in which a detecting accuracy can be improved without lowering an output of a sensor without obstructing a reduction in size of the detector and to provide a bearing for a wheel having the same. SOLUTION: This rotational speed detector 26 comprises a magnetic encoder 20 multi-pole magnetized circumferentially and the sensor 15 opposed to the encoder 20 to detect a rotational speed. When a sensor gap δ is 0.5 to 2.0 mm if the circumferential pole width W of the encoder 20 is 2 mm or less, an encoder one side piece sectional height (e) is set to a larger value of the about 2 mm and the height (e) of a formula e=d+0.4δ+0.55 (mm) is one side eight of the encoder 20 perpendicular to the circumferential pole width W of the encoder 20 from a center of the sensor 15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotation speed detecting device for detecting a rotation speed of a wheel or the like, and a wheel bearing having the same.

[0002]

2. Description of the Related Art As a device for detecting the rotational speed of a wheel or the like, a magnetic encoder mounted on a rotating body and magnetic poles N and S alternately formed in the circumferential direction of the magnetic encoder are used. There is known a sensor configured to detect a magnetic flux. The sensor in this case is composed of, for example, a Hall element. FIGS. 17A and 17B show two examples of the magnetic encoder in the rotation speed detecting device having the above configuration. The magnetic encoder 50 shown in FIG.
Is an axial type sensor that detects magnetic fluxes of the magnetic poles N and S in a direction opposed to each other with a predetermined sensor gap (air gap) in the axial direction. The magnetic encoder 60 shown in FIG. This is a radial type sensor that detects magnetic fluxes of the magnetic poles N and S with sensors arranged in opposite directions via a predetermined sensor gap.

In order to increase the detection accuracy of such a rotational speed detecting device, it is necessary to reduce the width W of the magnetic poles N and S. FIG. 18 is a graph showing a calculation example of the relationship between the surface magnetic flux density of the magnetic poles N and S when the width W of the magnetic poles N and S is changed, and the sensor gap between the magnetic poles N and S of the magnetic encoders 50 and 60 and the sensor. It is a thing. According to this graph, for example, when the magnetic pole width W is reduced from 2 mm to 1 mm when the sensor gap is 0.5 mm, the magnetic flux density is reduced to about 1/2.

According to the test results, if the magnetic pole width W of the magnetic encoder is narrowed and the detection accuracy of the rotation speed detecting device is increased, the magnetic flux density of the magnetic poles N and S is reduced. In the detection at, the sensor output decreases. Therefore, instead of reducing the magnetic pole width W, the height dimension E of the magnetic poles N and S (the radial dimension in the axial type magnetic encoder 50; the radial type magnetic encoder 60)
In this case, it is conceivable to increase the axial dimension), but increasing the height dimension E goes against miniaturization of the magnetic encoder.

SUMMARY OF THE INVENTION An object of the present invention is to provide a rotational speed detecting device capable of improving detection accuracy without impairing miniaturization of the device and without reducing sensor output, and a wheel bearing provided with the same. That is.

[0006]

According to the present invention, there is provided a rotational speed detecting device comprising: a magnetic encoder having a multipolar magnetization in a circumferential direction; and a sensor facing the magnetic encoder and detecting the rotational speed. When the magnetic pole width in the circumferential direction of the magnetic encoder is 2 mm or less and the gap δ between the magnetic encoder and the sensor is 0.5 to 2.0 mm, the height of one side section of the sensor from the center of the sensor is d. Then, the one-side cross-sectional height e in a direction perpendicular to the circumferential magnetic pole width of the magnetic encoder from the center of the sensor is approximately 2 mm or e = d + 0.4δ + 0.55 (mm), whichever is larger. I do. From the results of the analysis, it was found that when the value of the one-side cross-sectional height e was determined as described above, the magnetic flux density detected by the sensor could be maximized, and the height of the magnetic encoder magnetic pole could be minimized. . Therefore, by setting the value of e, the detection accuracy can be improved without hindering downsizing of the device and without lowering the sensor output.

In the present invention, the sensor may be an active sensor including a Hall element. An active sensor composed of a Hall element has a simple structure and is generally used as a magnetic sensor. However, when the magnetic flux density decreases, the sensor output also decreases in proportion to this. But,
By setting the value of the one-side cross-sectional height e of the magnetic encoder as described above, the detection accuracy can be improved without hindering downsizing of the device and without reducing the sensor output.

In the present invention, the magnetic encoder is formed by vulcanizing and bonding an elastic member containing a magnetic powder mixed to a steel plate core, and alternately forming magnetic poles in a circumferential direction on the elastic member. There may be. In the case of this configuration, the manufacture is simple, and the work of attaching to the device is simple. Even in the case of such a magnetic encoder, its one-side sectional height e
Is set to the above value, the magnetic flux density detected by the sensor can be maximized, and the height of the magnetic encoder magnetic pole can be suppressed to the minimum necessary.

A wheel bearing according to the present invention includes the rotation speed detecting device according to any one of the above-described structures of the present invention. In the periphery of the wheel bearing, it is difficult to secure a sufficient space for the detectors at the time of general use, and there is a strong demand for downsizing of the rotation speed detection device. The rotation speed can be accurately and reliably detected with a compact configuration. For this reason,
For example, when an anti-rotch brake system that uses the output of the rotation speed detecting device for control is configured, the accuracy and reliability of the brake system can be improved.

In the present invention, the wheel bearing includes an outer member having a double-row rolling surface formed on an inner peripheral surface, a rolling surface facing the rolling surface of the outer member, and a wheel mounting flange. A wheel bearing for supporting a wheel rotatably with respect to a vehicle body, comprising a formed inner member and a double row of rolling elements interposed between the two rolling surfaces; A sealing device for sealing an annular space with the first member, the sealing device having an L-shaped cross section, and a first sealing plate fitted to a rotation-side member of the outer member or the inner member; When,
A second seal plate having an L-shaped cross section, which is fitted to an end of the outer member and faces the first seal plate, and which slides on an upright portion of the first seal plate; The lip and the radial lip that is in sliding contact with the cylindrical portion may be vulcanized and bonded to the second seal plate, and the upright plate portion of the first seal plate may form a part of the magnetic encoder.

According to this configuration, the magnetic encoder of the rotational speed detecting device can be incorporated as a part of the seal device of the bearing, so that the rotational speed detecting device can be installed with good assembling property and compactly. In the sealing device, high sealing performance is obtained by each lip sliding between the first and second sealing plates, but the arrangement portion of the sealing device is a very limited space due to peripheral members. Therefore, the use of the rotation speed detecting device according to the present invention has a large effect in that the output is secured with a small size and high accuracy.

[0012]

FIG. 1 shows a first embodiment of the present invention.
7 will be described with reference to FIG. FIG. 1 is a partial longitudinal sectional view of the rotation speed detecting device of this embodiment. This rotation speed detecting device 26 includes a magnetic encoder 20 attached to a rotating body,
The magnetic encoder 20 includes a sensor 15 that is arranged opposite to the magnetic encoder 20 in the axial direction with a predetermined sensor gap δ to detect the rotational speed. The magnetic encoder 20 is of an axial type, and is made of a steel core 1 having an L-shaped cross section.
An elastic member 14 mixed with magnetic powder is vulcanized and adhered to the surface of the first standing portion 11b. The steel plate used as the core metal 11 is preferably a ferromagnetic material. The elastic member 14 is, for example, a rubber magnet. The elastic member 14, as shown in FIG.
It is multipolar magnetized in the circumferential direction. That is, the magnetic poles N and S are formed alternately in the circumferential direction. The magnetic poles N and S are formed to have a pitch p of a predetermined width in the pitch circle diameter PCD. The center of the sensor 15 is the pitch circle diameter PCD
Are arranged to match.

The sensor 15 opposed to the magnetic encoder 20 is an active type sensor comprising a Hall element 25 shown in FIG. When a predetermined current Ic flows in a predetermined direction perpendicular to magnetic fluxes generated from the magnetic poles N and S of the magnetic encoder 20, the Hall element 25 is perpendicular to the magnetic flux and parallel to the flow direction of the current Ic. and outputs the Hall voltage V _H that is proportional to the magnetic flux density B in the perpendicular direction sensor output. Note that the Hall voltage V _{H is changed} to the current Ic
When expressed in terms of magnetic flux density B, V _H = K × Ic × B. Here, K is a proportional constant.

In this embodiment, the size of the magnetic poles N and S of the magnetic encoder 20 is optimized in accordance with the size of the sensor 15 so that the average magnetic flux density transmitted through the sensor 15 is maximized. . Specifically, when the magnetic pole width W along the circumferential direction of the magnetic encoder 20 is 2 mm or less, and the sensor gap δ between the magnetic encoder 20 and the sensor 15 is 0.5 to 2.0 mm, the sensor Assuming that one-side cross-section height of the sensor 15 from the center is d,
The one-side cross-sectional height e in the direction perpendicular to the circumferential magnetic pole width of the magnetic encoder 20 from the sensor center is approximately 2 mm or e = d + 0.4δ + 0.55 (mm), whichever is larger.

The grounds for setting the dimensions of the magnetic encoder 20 in this manner will be described below with reference to the analysis result graphs shown in FIGS. FIG. 5 shows the magnetic pole width W = 2.0 m.
m, sensor gap δ = 0.5-2.0 mm,
Magnetic flux at the center of the sensor 15 when the one-side cross-sectional height e of the magnetic encoder 20 (one-side dimension in the radial direction about the pitch circle diameter PCD in the elastic member 14 where the magnetic poles N and S are formed) is changed. Indicates the density (% of the maximum magnetic flux density). It can be seen from the figure that the magnetic flux density at the center of the sensor 15 can be almost maximized when the height e on one side of the encoder is about 2 mm.

From the analysis results shown in FIG. 5, it can be easily predicted that when the magnetic pole width W is smaller than 2.0 mm, the height e on one side of the encoder can be further reduced, but the magnetic pole width W is smaller than 2 mm. Then, the magnets serving as the magnetic poles N and S cannot be stably fixed to the magnetic encoder 20, which is not practical.

FIG. 6 shows that the height e on one side of the encoder is 2 m.
When m is set, the magnetic flux density distribution in the height direction of the sensor 15 at each sensor gap δ is shown. In this case, the height direction of the sensor 15 is the cross-sectional height e on one side of the encoder.
In the figure, the dimension on the outer diameter side from the center of the sensor 15 is indicated by a plus value, and the dimension on the inner diameter side from the sensor center is indicated by a minus value. From this distribution diagram, in each sensor gap δ, the difference s between the encoder one-side cross-sectional height e and 95% of the maximum magnetic flux density and the sensor one-side cross-sectional height d (one-side dimension in the radial direction from the sensor center) is calculated as The result is shown in FIG. In the figure, a solid line graph A is a graph in which the value of the difference s is made to correspond to the sensor gap δ. The relationship between the difference s represented by the line graph A and the sensor gap δ is approximated by a linear expression of approximately s = 0.4δ + 0.55 (mm) when the sensor gap δ is in the range of 0.5 to 2 mm. Can be. A graph of the approximate expression is shown by a broken line B in FIG.

The result is that if the one-side cross section height of the sensor is d, and the one-side cross section height e of the magnetic encoder 20 is approximately e = d + 0.4δ + 0.55 (mm), the magnetic flux transmitted through the sensor 15 This indicates that the density is 95% or more of the maximum magnetic flux density.

For these reasons, the magnetic encoder 20
The size of the magnetic poles N and S in the circumferential direction, ie, the magnetic pole width W is 2
mm or less and the sensor gap δ is equal to 0.
When the range is 5 to 2.0 mm, the magnetic encoder 2
By setting the one-side cross-sectional height e of 0 to 2 mm as described above or e = d + 0.4δ + 0.55 (mm), whichever is larger, the magnetic flux density detected by the sensor 15 is maximized, The magnetic pole height of the magnetic encoder 20 can be minimized. As a result, the detection accuracy can be improved without hindering the downsizing of the rotation speed detecting device 26 and without lowering the sensor output.

Incidentally, the rotation speed detecting device 26 of this embodiment
8, the detection surface 15a of the sensor 15 facing the magnetic encoder 20 may be coated with a coating layer 21 having good slidability. This coating layer 21 may be brought into contact with the surface of the magnetic encoder 20. The coating layer 21 is, for example, a thin film. Magnetic encoder 2
In the case where 0 is a magnetic pole formed on the elastic member 14 as described above, the coating layer 21 is brought into contact with the surface of the elastic member 14. The coating layer 21 is a non-magnetic material and is preferably made of a material having good slippage, for example, a silicon resin, a fluororesin, a rubber having good sliding properties, or the like.

As described above, by providing the covering layer 21 on the sensor 15 and bringing the sensor 15 into contact with the magnetic encoder 20, foreign matter is prevented from being caught and the sensor 15 and the magnetic encoder 20 are prevented from being damaged. In addition, the sensor 15
Is in contact with the surface of the magnetic encoder, so that the magnetic gap can be easily managed.

The smaller the air gap between the magnetic encoder 20 and the sensor 15, the higher the magnetic flux density and the better the magnetic characteristics such as the pitch accuracy. However, the mounting accuracy of the magnetic encoder 20 and the sensor 15, and the deflection of the magnetic encoder 20. Taking into account the air gap, there is naturally a limit,
Usually, it is often set to about 0.5 to 2.0 mm. In the case of a wheel bearing, dust, stepping stones and the like bite into this air gap, and the magnetic encoder 20 and the sensor 15
May be damaged. In order to solve such a problem, a dust seal may be provided around the rotation speed detecting device or a cover may be attached, but this is not preferable in terms of space and cost. A coating layer 21 of a thin film with good slip on the detection surface 15a of the sensor 15 composed of a Hall element
The air gap can be made as small as possible. The surface of the magnetic encoder 20
In the case of the axial type, the perpendicularity and flatness with respect to the fitting portion appear as runout of the surface to be detected, and in consideration of damage to the sensor 15, this maximum runout is also a factor that must increase the air gap. I have. However, if the coating layer 21 having good sliding characteristics is provided on the detection surface 15a of the sensor 15, even if the magnetic encoder 20 and the sensor 15 come into contact during rotation, the torque increases, Damage can be kept extremely small. Thereby, the air gap can be set small, and not only the magnetic characteristics can be improved, but also the dust and stepping stones can be reduced, and the durability of the magnetic encoder 20 and the sensor 15 can be improved. Magnetic encoder 20 and sensor 15
Sensor 1
At the time of positioning of the sensor 5, it is possible to set the sensor 15 by lightly contacting the magnetic encoder 20, so that the mounting work of the sensor 15 can be simplified and the positioning accuracy can be further improved.

9 to 11 show another embodiment of the present invention. The rotation speed detecting device 46 of this embodiment is the same as that shown in FIG.
As shown in the vertical cross-sectional view of FIG. 2, the magnetic encoder 40 includes a radial type magnetic encoder 40 and a sensor 35 disposed to face the outer diameter side of the magnetic encoder 40. Magnetic encoder 40
Is composed of a ring-shaped steel core 31 and an elastic member 32 provided on the outer periphery thereof. The elastic member 32 has a ring shape whose thickness in the radial direction is smaller than the width in the axial direction. The elastic member 32 has magnetic poles N and S alternately formed in the circumferential direction, and is, for example, a rubber magnet. However,
The direction in which the magnetic fluxes of the magnetic poles N and S are generated is the radial direction of the elastic member 32. The dimensional relationship between the magnetic encoder 40 and the sensor 35 is the same as in the first embodiment.

Also in this embodiment, the magnetic pole width W is 2 m.
m and the sensor gap δ is 0.5
The magnetic encoder 40
The height e on one side of the cross section is 2 mm or e = d + 0.4δ +
By setting to 0.55 (mm), whichever is larger, the magnetic flux density detected by the sensor 35 is maximized, and the magnetic pole height of the magnetic encoder 40 can be suppressed to a necessary minimum. As a result, the detection accuracy can be improved without hindering downsizing of the rotation speed detecting device 46 and without lowering the sensor output.

Also in this embodiment, as shown in FIG. 12, the detection surface 35a of the sensor 35 may be coated with a coating layer 41 made of a non-magnetic material having good slidability. Also,
In installing the sensor 35, the surface of the coating layer 41 may be arranged so as to contact the surface of the elastic member 32 of the magnetic encoder 40.

With this configuration, it is possible to prevent foreign matters such as dust and flying stones from being caught in the sensor gap δ and damage the magnetic encoder 40 and the sensor 35, thereby improving durability. Speed detector 4
Compared to a case where a dust seal or a cover is attached around 6, the space can be saved and the cost can be reduced. Also,
In positioning the sensor 35, the small sensor gap δ can be easily and accurately set, the mounting work of the sensor 35 can be simplified, and the magnetic characteristics can be improved.

FIG. 13 is a cross-sectional view of a wheel bearing provided with the axial type rotation speed detecting device 26 according to the first embodiment. This 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 end annular space between the inner and outer members 1 and 2. And sealing devices 5 and 13 for sealing. The sealing device 5 at one end has an axial type magnetic encoder 20. The inner member 1 and the outer member 2 include a rolling element 3
Rolling surface 1a, 2a, and each rolling surface 1a, 2a
Are formed in a groove shape. Inner member 1 and outer member 2
Are members on the inner peripheral side and members on the outer peripheral side, which are rotatable with each other via the rolling elements 3, and may be a single bearing inner ring and a single bearing outer ring. Also, the inner member 1
May be an axis. The rolling element 3 is formed of a ball or a roller. In this example, a ball is used.

This wheel bearing is a double row rolling bearing, more specifically, a double row angular contact ball bearing. The inner ring of the bearing fits with the hub wheel 6 and the outer diameter of the end of the hub wheel 6. And a separate inner ring 1A. A rolling surface 1a of each rolling element row is formed on the hub wheel 6 and the separate inner ring 1A.

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 flange 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 a drive shaft (not shown). The outer member 2 is formed of a bearing outer ring having a flange 2b, and is attached to a housing 10 formed of a knuckle or the like. The outer member 2 includes the rolling surfaces 2a,
2a. The rolling elements 3 are held by a holder 4 for each row.

FIG. 14 shows the sealing device 5 in an enlarged manner.
The seal device 5 includes first and second annular seal plates 11A, 1A attached to the inner member 1 and the outer member 2, respectively.
2 These seal plates 11A and 12 are attached to the inner member 1 and the outer member 2 by being fitted in a press-fit state, respectively. The two seal plates 11A and 12 are formed in an L-shaped cross section including the cylindrical portions 11a and 12a and the upright plates 11b and 12b, and face each other. The first seal plate 11A 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 magnetic powder is mixed into the outer side surface thereof. The elastic member 14 is vulcanized and bonded. The elastic member 14 and the first seal plate 11A constitute the magnetic encoder 20 according to the first embodiment. The first seal plate 11A is made of the metal core 11 in the first embodiment. The sensor 15 is disposed so as to face the elastic member 14 of the magnetic encoder 20 in the axial direction.
Is configured. The rotation speed detecting device 26 has the respective dimensional conditions in the first embodiment.

The second seal plate 12 is a first seal plate 1
A side lip 16a slidingly contacting the 1A standing plate portion 11b and radial lips 16b and 16c slidingly contacting the cylindrical portion 11a are integrally provided. These lips 16a to 16c
Is provided as a part of the elastic member 16 which is vulcanized and bonded to the seal plate 12. The second seal plate 12 holds the elastic member 16 in a fitting portion with the outer member 2 which is a fixed-side member. The cylindrical portion 12a of the second seal plate 12
And the front end of the upright portion 11b of the first seal plate 11A are opposed to each other with a slight radial gap, and the gap forms the labyrinth seal 17.

According to the wheel bearing of this configuration, the rotation speed of a wheel (not shown) mounted on the inner member 1 is detected by the rotation speed detecting device 26 including the magnetic encoder 20 and the sensor 15. Since the magnetic encoder 20 of the rotation speed detecting device 26 is incorporated in the bearing as a part of the seal device 5, the rotation speed detecting device 26 can be installed with good assembling property and compactly. The sealing device 5 includes lips 16 a to 16 slidably contacting between the first and second seal plates 11 </ b> A and 12.
A high sealing performance can be obtained with c and the labyrinth seal 17. The arrangement portion of the sealing device 5 is a very limited space due to the constant velocity universal joint 7 and other peripheral members. However, since the rotation speed detecting device 26 having dimensions as described above is used, the sealing device 5 is small and compact. High accuracy and high output can be obtained.

FIG. 15 is a cross-sectional view of a wheel bearing provided with the radial type rotation speed detecting device 46 in the above embodiment. In this wheel bearing, the outer member 2 is a member on the rotation side, and is formed of an integral bearing outer ring also serving as a hub wheel. The inner member 1 is a member on the fixed side, and includes a pair of split type inner rings 1.
B, 1C. The rolling elements 3 are held by a holder 4 for each row.

As shown in FIG. 16, the sealing device 5 in this embodiment is similar to the sealing device of the embodiment shown in FIGS. 13 and 14 in that the first and second annular sealing plates 11A and 12 are The first seal plate 11A is not used as a magnetic encoder, although the elastic member 16 has lips 16a to 16c.

In this wheel bearing, a radial magnetic encoder 40 is fitted around the outer periphery of one end of the outer member 2. This magnetic encoder 40 is a magnetic encoder 4 of the rotation speed detecting device 46 in the embodiment shown in FIGS.
0. By arranging the sensor 35 so as to face the elastic member 32 of the magnetic encoder 40 in the radial direction, a rotation speed detecting device 46 is configured. Sensor 3
5 is provided on the fixing member. Other configurations of the rotation speed detecting device 46 are the same as those of the rotation speed detecting device 26 in the embodiments of FIGS. 9 to 11.

In the bearing for a wheel having this configuration, the rotational speed detecting device 46 also has the dimensional conditions of the above-described embodiment. Therefore, it is possible to reduce the sensor output without hindering the downsizing of the rotational speed detecting device 46. And the wheel rotation speed can be detected with high accuracy.

[0037]

According to the present invention, there is provided a rotational speed detecting device comprising: a magnetic encoder having a multipolar magnetization in a circumferential direction; and a sensor facing the magnetic encoder and detecting the rotational speed. Circumferential magnetic pole width of 2
mm and the gap δ between the magnetic encoder and the sensor is 0.5 to 2.0 mm, and the height of one side section of the sensor from the center of the sensor is d. The one-side cross-sectional height e in the direction perpendicular to the direction magnetic pole width is approximately 2 mm, or e = d + 0.4δ.
+0.55 (mm), whichever is greater, can improve the detection accuracy without hindering downsizing of the device and without reducing the sensor output. Since the wheel bearing of the present invention is provided with the rotational speed detecting device of the present invention, the wheel rotational speed can be detected accurately and reliably with a compact configuration.
In the wheel bearing provided with the rotation speed detecting device according to the present invention, the seal device of the bearing has each lip that slides between the first and second seal plates, and the first seal plate is one of the magnetic encoders. In the case of a part, the magnetic encoder of the rotation speed detecting device can be incorporated as a part of the seal device of the bearing, so that the rotation speed detecting device can be installed with good assembling property and compactly. In the sealing device, high sealing performance is obtained by each lip sliding between the first and second seal plates. The periphery of the seal device is a very limited space, and therefore, the use of the rotation speed detecting device of the present invention has a large effect in that the output can be secured with small size and high accuracy.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view of a rotation speed detecting device according to an embodiment of the present invention.

FIG. 2 is a perspective view of a magnetic encoder in the rotation speed detecting device.

FIG. 3 is an enlarged front view of a main part of the rotation speed detecting device.

FIG. 4 is an operation explanatory view of a Hall element constituting a sensor of the rotation speed detecting device.

FIG. 5 is a graph showing a relationship between a height of a cross section of one side of an encoder and a magnetic flux density in each sensor gap.

FIG. 6 is a graph showing the relationship between the height of one sensor cross section and the magnetic flux density in each sensor gap.

FIG. 7 is a graph showing a relationship between a sensor gap and a difference between an encoder / sensor section height.

FIG. 8 is a partial cross-sectional view showing a modification of the rotation speed detecting device.

FIG. 9 is a sectional view of a rotation speed detecting device according to another embodiment of the present invention.

FIG. 10 is a perspective view of a magnetic encoder in the rotation speed detecting device.

FIG. 11 is an enlarged front view of a main part of the rotation speed detecting device.

FIG. 12 is a sectional view showing a modification of the rotation speed detecting device.

FIG. 13 is a sectional view of a wheel bearing according to another embodiment of the present invention.

FIG. 14 is a partial cross-sectional view of the seal device for the wheel bearing.

FIG. 15 is a sectional view of a wheel bearing according to still another embodiment of the present invention.

FIG. 16 is a partial sectional view of the seal device for the wheel bearing.

17A is a perspective view of an axial type magnetic encoder of a conventional rotation speed detecting device, and FIG. 17B is a perspective view of a radial magnetic encoder of the same rotation speed detecting device.

FIG. 18 is a graph showing the relationship between the magnetic pole surface magnetic flux density and the sensor gap when the magnetic pole width of the magnetic encoder is changed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Inner member 2 ... Outer member 1a, 2a ... Rolling surface 3 ... Roller element 5 ... Seal device 6a ... Flange 11 ... Steel core 11a ... Cylinder portion 11b ... Stand plate portion 11A ... First seal plate DESCRIPTION OF SYMBOLS 12 ... 2nd sealing plate 14 ... Elastic member 15 ... Sensor 16a ... Side lip 16b, 16c ... Radial lip 20 ... Encoder 25 ... Hall element 26 ... Rotation speed detector 31 ... Steel core 32 ... Elastic member 35 ... Sensor Reference numeral 40: magnetic encoder 46: rotational speed detecting device W: circumferential magnetic pole width δ: sensor gap d: sensor one-side section height e: encoder one-side section height

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G01D 5/245 G01D 5/245 HV (72) Inventor Takayuki Norimatsu 1578 Higashikaizuka, Iwata City, Shizuoka Prefecture In-house F term (reference) 2F077 AA41 AA42 NN04 NN09 NN18 PP12 VV03 VV31 3J016 AA02 AA03 BB03 BB16 CA03 3J101 AA02 AA32 AA43 AA54 AA62 FA23 FA41 FA53 GA03

Claims (5)

[Claims] 1. A rotation speed detecting device comprising: a magnetic encoder magnetized in the circumferential direction with multipolar magnetization; and a sensor facing the magnetic encoder and detecting a rotation speed, wherein a circumferential magnetic pole width of the magnetic encoder is 2 mm or less. In this case, when the gap δ between the magnetic encoder and the sensor is 0.5 to 2.0 mm, and the height of one cross section of the sensor from the sensor center is d, the circumferential magnetic pole width of the magnetic encoder from the sensor center is d. And one-side cross section height e perpendicular to
Is set to be approximately 2 mm or e = d + 0.4δ + 0.55 (mm), whichever is larger. 2. The rotation speed detecting device according to claim 1, wherein the sensor is an active sensor including a Hall element. 3. The magnetic encoder according to claim 1, wherein an elastic member in which a magnetic powder is mixed is vulcanized and bonded to a steel core, and magnetic poles are alternately formed on the elastic member in a circumferential direction. The rotation speed detecting device according to claim 2. 4. A wheel bearing comprising the rotation speed detecting device according to any one of claims 1 to 3. 5. An outer member having a double-row rolling surface formed on an inner peripheral surface, an inner member having a rolling surface facing the rolling surface of the outer member and a wheel mounting flange, and A wheel bearing comprising a double row of rolling elements interposed between both rolling surfaces and rotatably supporting the wheel with respect to the vehicle body, wherein the annular space between the outer member and the inner member is sealed. A first sealing plate which has an L-shaped cross section and is fitted to a rotating side member of the outer member or the inner member; and a first sealing plate. Opposite
A side lip sliding on an upright portion of the first seal plate and a radial lip sliding on a cylindrical portion, the second lip comprising a second sealing plate having an L-shaped cross section fitted to an end of the outer member; 5. The wheel bearing according to claim 4, wherein the first sealing plate is vulcanized and bonded to the second sealing plate, and an upright portion of the first sealing plate forms a part of the magnetic encoder.