JP2007333182A - Seal structure with encoder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a seal structure with an encoder capable of detecting the rotating state of a bearing with high accuracy and low in cost with excellent manufacturing efficiency. <P>SOLUTION: The seal structure for sealing the inside of the bearing between a rotating ring 2 and a stationary ring 4 arranged facing each other, from the outside of the bearing, comprises an annular seal member 6 with its base end fixed to the rotating ring and with its tip extended toward the stationary ring; the annular encoder 8 provided on the bearing outer side of the seal member and provided with different magnetic poles alternately polarized on the surface along the circumferential direction; and an annular cover 10 put over the whole surface on the bearing outer side of the encoder. The whole of the cover extending from the inner diameter side 10a to the outer diameter side 10b is put in close contact over the whole surface of the encoder, and the whole of the cover is formed of a nonmagnetic rubber material. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a non-magnetic cover that covers an encoder surface particularly in a seal structure having an encoder for detecting the rotation state (for example, rotation speed, rotation direction) of a bearing.

  In recent years, with the increasing awareness of automobile safety, for example, ABS (Antilock Brake System) for ensuring running stability during braking on slippery road surfaces such as freezing has become widespread. Various bearings including a rotation detection mechanism capable of detecting a rotation state (for example, a rotation speed or a rotation direction of a wheel) have been proposed. The rotation detection mechanism includes a sensor fixed to a stationary wheel and an encoder fixed to the rotating wheel. The encoder has alternating magnetic poles having different N and S poles along its circumferential direction. Is magnetized. In this case, the rotation speed and direction of rotation of the wheel can be detected by detecting the change of the magnetic pole per unit time while the encoder is rotating together with the rotating shaft during vehicle braking.

  By the way, the encoder is formed by mixing, for example, a ferrite magnetic powder with a rubber material (binding material), and has a relatively spore structure as compared with a solid rubber material. For this reason, when the vehicle is exposed to a rebound environment of foreign matter such as earth and sand or muddy water for a long time, the surface of the encoder may be worn by the foreign matter. Depending on the degree of progress of wear, for example, the magnetic flux density of each magnetic pole of the encoder may fluctuate, which may reduce the detection accuracy of the sensor. Also, when magnetic powder generated when the encoder is worn adheres to the encoder surface, the magnetic flux density of the encoder varies in the same manner depending on the degree of adhesion of the magnetic component, which reduces the detection accuracy of the sensor. May end up.

  For this reason, the peripheral area of the encoder is designed so that a kind of labyrinth is formed by incorporating the peripheral parts, but that alone may not be sufficient to solve the above-described problems. . Thus, for example, Patent Document 1 proposes a technique in which a seal is disposed outside the encoder and rotation is detected from the outside of the seal. For example, Patent Document 2 proposes a technique in which the surface of an encoder is covered with a nonmagnetic cover and rotation detection is performed from the outside of the cover.

  However, in the technique of Patent Document 1, a relatively wide space is secured between the encoder and the sensor, including the air gap from the encoder to the seal, the thickness of the seal itself, and the air gap from the seal to the sensor. There must be. For this reason, the sensor is arranged at a position relatively distant from the encoder. In this case, depending on the distance between the encoder and the sensor, the magnetic action from the encoder received by the sensor becomes weak, so it is difficult to detect the change in the magnetic pole with high accuracy, and as a result, the rotation state of the bearing can be detected with high accuracy. May not be able to be detected. In addition, since the seal and the encoder overlap in the radial direction, the height of the cross section of the seal cannot be increased, and a large magnetic flux density cannot be expected.

On the other hand, in the technique of Patent Document 2, when the cover is attached, the cover must be press-fitted into the rotating wheel together with the slinger supporting the encoder. For this reason, it takes time to install the cover, and the manufacturing efficiency of the seal structure is lowered. Moreover, since the high precision is requested | required when processing a slinger and a cover, the manufacturing cost of a seal structure will rise. Furthermore, in the technique of Patent Document 2, if the encoder is magnetized while the cover is covered, the magnetizing device (magnetizing yoke) cannot be brought into close contact with the encoder surface. It may become difficult to do. Conversely, if the cover is covered after the magnetizing process, if the dust generated when the cover is pressed into the rotating wheel enters between the cover and the encoder, the magnetic flux density of the encoder will fluctuate. There is a risk that the accuracy may decrease. In either case, the rotational state of the bearing cannot be detected with high accuracy.
JP-A-10-160744 JP 2002-333033 A

  The present invention has been made to solve such a problem, and an object thereof is to provide a low-cost encoder-equipped seal structure excellent in manufacturing efficiency capable of detecting the rotation state of a bearing with high accuracy. There is.

  In order to achieve such an object, the present invention provides a seal structure that seals the inside of a bearing between a rotating wheel and a stationary ring that are arranged opposite to each other, the base end of which is the rotating wheel. An annular seal member that is fixed and has a tip extending toward the stationary ring, and an annular encoder that is provided outside the bearing of the seal member and has different magnetic poles alternately magnetized along the circumferential direction on the surface thereof And an annular cover coated on the entire outer surface of the bearing of the encoder, and the entire cover from the inner diameter side to the outer diameter side of the encoder is covered in close contact with the entire surface of the encoder. The whole is made of a nonmagnetic rubber material.

  In the present invention, the outer diameter side of the cover overturns the encoder and is folded back to the bearing inner side, and the inner diameter dimension of the outer diameter side of the cover is set to be relatively smaller than the outer diameter dimension of the encoder. In this case, the cover is formed separately from the encoder.

  According to the present invention, the encoder can achieve a high output by increasing the height of the end face, as in the prior art. By covering the entire outer surface of the bearing with a rubber cover, it is possible to realize a low-cost encoder-sealed seal structure with excellent manufacturing efficiency that can detect the rotational state of the bearing with high accuracy over a long period of time. it can.

  FIG. 1 (a) shows a configuration of a seal structure with an encoder according to an embodiment of the present invention, and this seal structure is a bearing between a rotating wheel 2 and a stationary wheel 4 arranged opposite to each other. The inside can be sealed against the outside of the bearing. In this configuration example, a bearing that rotatably supports a vehicle wheel (for example, a disc wheel) with respect to a vehicle body (for example, a suspension device) is assumed, and in this bearing, the rotating wheel 2 is connected to the wheel side. The stationary wheel 4 is provided so as to face the outside of the rotating wheel 2 and is fixed to the vehicle body side and is always kept in a non-rotating state.

  In such a seal structure, an annular seal member 6 having a base end fixed to the rotating wheel 2 and a distal end extending toward the stationary wheel 4, a seal member 6 provided outside the bearing, and An annular encoder 8 in which different magnetic poles are alternately magnetized along the circumferential direction on the surface, and an annular cover 10 that covers the entire surface of the encoder 8 outside the bearing are provided.

  Here, the seal member 6 is configured as a pack seal slinger, which will be described later, and a hollow cylindrical portion 6a fixed to the outer peripheral surface 2s of the rotating wheel 2 is provided on the proximal end side thereof, and on the distal end side thereof. Is provided with an annular folded portion 6b folded from the hollow cylindrical portion 6a toward the stationary wheel 4. In this case, it is preferable that the inner diameter of the hollow cylindrical portion 6 a is set slightly smaller than the outer diameter of the outer peripheral surface 2 s of the rotating wheel 2 before the seal member (slinger) 6 is fixed to the rotating wheel 2. Thereby, the hollow cylindrical part 6a can be firmly fixed to the outer peripheral surface 2s of the rotating wheel 2 by an interference fit.

  In addition to the above-described seal member (slinger) 6, the pack seal is further provided with a seal body that is always in sliding contact with the seal member 6. The seal body is fixed to the stationary wheel 4. In this case, the seal body is configured by adding a resin (rubber) sealing material 14 to the inner side of the mandrel 12 fixed to the stationary ring 4 (the surface facing the seal member 6). For example, three seal lips 14a, 14b, and 14c are integrally formed in the unit 14. The seal lips 14a, 14b and 14c are in sliding contact with the annular slinger surfaces M1 and M2 of the seal member (slinger) 6 facing each other.

  As a result, the inside of the bearing is sealed with respect to the outside of the bearing, for example, preventing leakage of lubricant (for example, oil or grease) to the outside of the bearing, and entry of foreign matter (for example, earth and sand, muddy water, etc.) be able to. In the seal structure of the present embodiment, the seal body is not an essential component, and sufficient sealing performance can be ensured with only the seal member 6 as a slinger.

  The encoder 8 is formed, for example, by mixing a ferrite magnetic powder with a rubber material (binding material), and magnetic poles having different N and S poles are alternately magnetized on the surface thereof along the circumferential direction. In this case, the encoder 8 is provided on the outside of the bearing of the annular folded portion 6b in the above-described seal member (slinger) 6.

  In addition, as a method of providing the encoder 8 in the annular folding portion 6b, for example, the encoder 8 is vulcanized, bonded, or screwed to the annular folding portion 6b, or, for example, if the seal member (slinger) 6 is made of metal. The encoder 8 may be magnetically attracted to the seal member 6 by the magnetic force of the encoder 8 itself. In either method, considering the cover state of the cover 10 to be described later, the outer diameter end of the encoder 8 is located on the inner diameter side of the outer diameter end of the seal member (slinger) 6 as shown in FIG. It is preferable that the position is shifted (retracted) by a predetermined amount W. In this case, the predetermined amount W is arbitrarily set according to the size and shape of the seal member 6 and the encoder 8, for example, and is not specifically limited here.

  Further, the cover 10 is formed by vulcanization molding of a non-magnetic rubber material as a whole, and a cover rich in elasticity is formed. It is also possible to reinforce the flat portion by inserting a non-magnetic material insert. As the nonmagnetic material for the insert, for example, 300 series stainless steel, the same alloy, aluminum or the like may be applied. Then, by mixing a solid rubber material (binding material) with such a nonmagnetic material and subjecting it to vulcanization treatment, the nonmagnetic cover 10 in which the cylindrical portion (outer diameter portion) is rich in elasticity can be formed. .

  The cover 10 has an outer diameter side 10b that passes over the outer diameter side of the encoder 8 and is folded back to the bearing inner side, and a folded tip 10c is folded to the bearing inner side of the seal member (slinger) 6 ( Be hooked). As a result, the encoder 8 is in a state where the outer diameter side is completely shielded from the outside of the bearing by the cover 10 and at the same time is sandwiched between the cover 10 and the seal member 6. In this case, the inner diameter dimension of the outer diameter side 10 b of the cover 10 is preferably set to be relatively smaller than the outer diameter dimension of the outer diameter end of the encoder 8.

  More specifically, as described above, the outer diameter end of the seal member (slinger) 6 is positioned by being displaced (retracted) by a predetermined amount W from the outer diameter end of the encoder 8 toward the inner diameter side. It is preferable to set the inner diameter dimension of the outer diameter side 10 b of the cover 10 to be smaller than the outer diameter dimension of the outer diameter end of the member 6. In this way, for example, as shown in FIG. 1B, when covering the encoder 8 with the cover 10, the outer diameter side 10b of the cover 10 is folded back in the direction of the arrow P1, and the folded tip 10c is extended. When it is folded (hanged) inside the bearing through the outer diameter of the slinger, a contraction force in the inner diameter direction acts on the cover 10 due to the elasticity of the rubber cover 10 itself.

  As a result, the cover 10 is elastically held by the seal member 6, and at the same time, the entire portion from the inner diameter side 10 a to the outer diameter side 10 b is in close contact with the entire surface of the encoder 8. In this case, the outer diameter side of the encoder 8 is completely covered with the cover 10 from the outside of the bearing, and at the same time, the entire surface thereof is covered with the cover 10 and the seal member 6 being sandwiched. .

  As described above, according to the present embodiment, the entire surface of the encoder 8 outside the bearing is covered with the solid rubber cover 10, so that, for example, during traveling, a foreign object such as earth and sand or muddy water is rebounded for a long time. Even when exposed, the surface of the encoder 8 is not worn by foreign matter as in the prior art. That is, the solid rubber cover 10 is more durable than the encoder 8 formed of a magnetic rubber material, so that the cover 10 deteriorates or wears even when exposed to a harsh environment for a long time. There is nothing. In this case, the encoder 8 covered with the cover 10 can be held at a constant magnetic flux density over a long period of time, whereby the detection accuracy of the sensor can be maintained constant over a long period of time. As a result, the rotational state of the bearing can be detected with high accuracy over a long period of time.

  Further, according to the present embodiment, since the entire portion from the inner diameter side 10a to the outer diameter side 10b of the cover 10 can be covered and covered with the entire surface of the encoder 8, a sensor (not shown) is provided close to the encoder 8. Not) can be placed opposite each other. In this case, since the magnetic action from the encoder 8 received by the sensor can be maintained at a constant strength over a long period of time, a change in the magnetic pole can be detected with high accuracy. As a result, the rotational state of the bearing can be detected with high accuracy over a long period of time.

  Furthermore, according to the present embodiment, the cover 10 can be attached in a short time and reliably by simply folding (hanging) the folded tip 10c of the cover 10 into the bearing inner side of the seal member (slinger) 6. Can be coated. In this case, since the attaching operation of the cover 10 is simplified, the manufacturing efficiency of the seal structure can be improved. Moreover, since the high processing precision with respect to the encoder 8 and the seal member 6 is not requested | required, the manufacturing cost of a seal structure can be reduced.

  In the magnetizing process for the encoder 8, the magnetizing process may be performed in a state where the encoder 8 is covered with the cover 10. However, the cover 10 of the present embodiment is made of rubber, and the outer diameter side 10b thereof is, for example, It can be easily removed simply by elastic deformation in the direction of arrow P2 in FIG. In this case, since the magnetizing device (magnetizing yoke) can be brought into close contact with the surface of the encoder 8 during the magnetizing process, the encoder 8 can be magnetized accurately. When the cover 10 is covered after the magnetizing process, the folded tip 10c of the cover 10 is merely hooked on the seal member (slinger) 6, and therefore no dust is generated. That is, the problem that dust enters between the cover 10 and the encoder 8 does not occur.

  In the above-described embodiment, the cover 10 is exemplified as a configuration (FIG. 1) that covers the outer diameter side and the entire surface of the encoder 8, but as a modified example, for example, as shown in FIG. An annular extending covering portion 16 that extends over the inner diameter side of the encoder 8 and extends to the seal member (slinger) 6 may protrude from the inner diameter side 10a. As a result, in addition to the outer diameter side and the entire surface of the encoder 8, the inner diameter side thereof is also covered with the cover 10, and the encoder 8 can be maintained in a completely sealed state from the outside. .

(a) is sectional drawing which shows the structure of the seal structure with an encoder which concerns on one embodiment of this invention, (b) is sectional drawing which shows the state which coat | covers an encoder with a cover. Sectional drawing which shows the structure of the seal structure with an encoder which concerns on the modification of this invention.

Explanation of symbols

2 Rotating wheel 4 Stationary wheel 6 Seal member 8 Encoder 10 Cover 10a Inner diameter side of cover 10b Outer diameter side of cover

Claims (3)

A seal structure that seals the inside of the bearing between the rotating wheel and the stationary wheel arranged opposite to each other with respect to the outside of the bearing,
An annular seal member whose proximal end is fixed to the rotating wheel and whose distal end extends toward the stationary wheel;
An annular encoder which is provided on the bearing outer side of the seal member, and whose surfaces are alternately magnetized with different magnetic poles along the circumferential direction;
And an annular cover that covers the entire outer surface of the encoder bearing,
The cover is covered with the entire surface from the inner diameter side to the outer diameter side in close contact with the entire surface of the encoder, and is entirely formed of a nonmagnetic rubber material. .   The cover has an outer diameter side that passes over the encoder and is folded back to the inside of the bearing, and the inner diameter dimension of the cover on the outer diameter side is set to be relatively smaller than the outer diameter dimension of the encoder. The seal structure with an encoder according to claim 1. The seal structure with an encoder according to claim 1, wherein the cover is formed separately from the encoder.

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