JP2015081657A - Protective cover and bearing device including protective cover - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a protective cover capable of restricting magnetic permeability low after it is molded into a cup-shape through pressing work.SOLUTION: This invention relates to a bearing device 11 comprising: a bearing including an inner ring 12 formed with an inner ring raceway surface 12A at its outer circumferential surface, an outer ring 13 formed with an outer ring raceway surface 13A at its inner circumferential surface, and rollers 14 rolling between the inner ring raceway surface 12A and the outer ring raceway; a magnetic encoder 8 positioned at one end part of the bearing in an axial direction and having N-poles and S-poles alternatively arranged in a specified interval in a circumferential direction; and a sensor fixed to the outer ring 13 so as to detect rotation of the magnetic encoder 8 in opposition to a polarity of the magnetic encoder 8, and a cup-shaped protection cover 1 press fitted into the outer ring 13 to cover the magnetic encoder 8 and present between the magnetic encoder 8 and the sensor is molded by press working from a plate member made of austenite stainless steel including a specified amount of copper.

Description

  The present invention relates to a protective cover that is press-fitted into an outer ring of a bearing and covers a magnetic encoder, and a bearing device including the protective cover.

The anti-lock brake device (anti-skid brake device) that efficiently and safely brakes without locking the wheel of the automobile has a mounting rate of 90% as compared to 2009, which was 45% in 1996. % Is over.
The anti-lock brake device widely used in this way, for example, detects the rotational speed of each wheel by a rotational speed detection device (wheel speed sensor), calculates acceleration and deceleration by the control device, and also detects the vehicle speed and slip. The rate is estimated, and the actuator is driven based on the result to control the brake fluid pressure.

A bearing device provided with such a rotational speed detection device in a rolling bearing (hub bearing) for supporting a wheel of an automobile is also widely used, and an inner side between opposed surfaces of an inner ring on a rotating side and an outer ring on a fixed side. A seal member is attached to the inner ring, and a magnetic encoder in which N poles and S poles are alternately arranged in the circumferential direction at regular intervals is attached to the inner ring on the inner side of the seal member, and a sensor for detecting the rotation of the magnetic encoder is magnetically mounted. Some are attached to the outer ring so as to face the encoder (for example, see Patent Document 1).
Here, in the configuration of the bearing device as in Patent Document 1, muddy water or magnetized iron pieces or the like may enter between the magnetic encoder and the sensor, which may damage the magnetic encoder or the sensor. May change the magnetic properties. In addition, the rotational torque of the bearing device increases due to the sliding resistance of the seal member located on the outer side of the magnetic encoder.
Therefore, in order to solve these problems, there is one in which the sealing member is eliminated and a protective cover formed in a cup shape so as to cover the magnetic encoder from the inner side is press-fitted into the inner side end of the outer ring. (For example, refer to Patent Document 2).

JP 2005-241351 A JP 2011-084265 A

The cup-shaped protective cover as in Patent Document 2 is nonmagnetic so that the protective cover does not disturb the magnetic field and adversely affect the detection accuracy when the periodic magnetic characteristic change of the magnetic encoder is detected by the sensor. Generally, it is formed by press working from a plate material made of stainless steel (SUS304) having high rust prevention performance.
However, the inventors of the present invention have studied based on the recent situation in which the demand for improving the detection accuracy of the rotational speed detection device is increasing, and as a result, a cup is formed by pressing from a stainless steel (SUS304) plate material. In the case of forming a protective cover, it has been found that when the degree of processing increases, the magnetic permeability increases rapidly, that is, it becomes easier to magnetize.

When a protective cover that is easily magnetized after processing is used, the protective cover disturbs the magnetic field of the magnetic encoder, so that the detection accuracy of the rotational speed detection device is lowered.
Therefore, particularly when the demand for improving the detection accuracy of the rotational speed detection device is severe, it is necessary to improve the magnetic permeability after processing of the protective cover formed into a cup shape by pressing.

  Therefore, in view of the above-described situation, the present invention intends to solve the problem by providing a protective cover that can suppress the magnetic permeability after being formed into a cup shape by pressing.

  In order to solve the above problems, the protective cover according to the present invention includes an inner ring having an inner ring raceway surface formed on an outer peripheral surface, an outer ring having an outer ring raceway surface formed on an inner peripheral surface, and the inner ring raceway surface and the outer ring. A bearing having a rolling element that rolls between raceway surfaces, and a magnetic encoder that is positioned at one end in the axial direction of the bearing and is fixed to the inner ring and alternately arranged in the circumferential direction at a constant interval in the circumferential direction In addition, in the bearing device that is fixed to the outer ring and includes a sensor for detecting the rotation of the magnetic encoder facing the magnetic pole of the magnetic encoder, the outer ring is press-fitted so as to cover the magnetic encoder, A cup-shaped protective cover interposed between the magnetic encoder and the sensor, wherein the cover is formed by pressing from an austenitic stainless steel plate containing a certain amount of copper. To.

According to such a configuration, since the protective cover is formed by press working from a plate made of austenitic stainless steel containing a certain amount of copper, the conventional one made of austenitic stainless steel (SUS304) not containing copper Compared with, the magnetic permeability does not increase even if the degree of processing is increased, so it is difficult to magnetize, and the protective cover does not disturb the magnetic field of the magnetic encoder. The accuracy does not decrease.
In addition, since there is no restriction that the degree of processing cannot be increased as in the case of using SUS04 as a plate material for the protective cover, the degree of freedom in design is increased, and the demand for improving the detection accuracy of the rotational speed detection device is severe. Can also handle cases.
Furthermore, by forming the base portion of the protective cover by press working from an austenitic stainless steel plate material containing a certain amount of copper, the workability is hard to be hardened by drawing in press working and the workability is improved.

The bearing device according to the present invention includes the protective cover.
It is characterized by.

  According to the protective cover and the bearing device including the protective cover according to the present invention as described above, the magnetic permeability does not increase even if the degree of processing at the time of forming the protective cover is increased. Since the magnetic field of the magnetic encoder is not disturbed, there are significant effects such as that the detection accuracy of the rotational speed detection device does not decrease.

It is a longitudinal section of a bearing device provided with a protection cover concerning an embodiment of the invention. It is the principal part enlarged vertical sectional view similarly. The protective cover which concerns on embodiment of this invention is shown, (a) is a longitudinal cross-sectional view, (b) is a perspective view. It is a figure which shows the change of the relative magnetic permeability by a cold rolling ratio.

  Next, embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments shown in the accompanying drawings, and includes all the embodiments that satisfy the requirements described in the claims. It is a waste.

As shown in a longitudinal sectional view of FIG. 1 and an enlarged longitudinal sectional view of a main part of FIG. 2, a bearing device 11 according to an embodiment of the present invention includes an inner ring 12 having an inner ring raceway surface 12A formed on an outer peripheral surface, and A bearing having an outer ring 13 having an outer ring raceway surface 13A formed on the inner peripheral surface, rolling elements 14, 14,... Rolling between the inner ring raceway surface 12A and the outer ring raceway surface 13A, and one axial end of the bearing. A magnetic encoder 8 positioned on the inner ring 12 and fixed to the inner ring 12; a sensor 10 for detecting rotation of the magnetic encoder 8 facing the magnetic pole of the magnetic encoder 8 fixed to the outer ring 13; A cup-shaped protective cover 1 press-fitted into the outer ring 13 so as to cover and interposed between the magnetic encoder 8 and the sensor 10 and a seal member 15 disposed at the other axial end of the bearing are provided.
Therefore, the inside of the bearing is sealed by the protective cover 1 and the seal member 15 at both ends in the axial direction of the bearing, and the magnetic encoder 8 is accommodated in the internal space, so that the magnetic encoder 8 and the inside of the bearing are protected from foreign matters and the like. it can.
Here, the magnetic encoder 8 attached to the inner ring 12 on the rotating side, in which the N pole and the S pole are alternately arranged in the circumferential direction at regular intervals, and the sensor 10 attached to the outer ring 13 on the fixed side are rotated. A speed detection device is configured.

The support member 9 includes a cylindrical portion 9A and an annular portion 9B extending radially outward from the end of the cylindrical portion 9A. The N pole and the S pole are alternately arranged in the circumferential direction at regular intervals on the annular portion 9B. The magnetic encoder 8 arranged in a row is fixed.
Therefore, by fitting the cylindrical portion 9 </ b> A to the inner ring 12, the magnetic encoder 8 is fixed to the inner ring 12 via the support member 9, so that the magnetic encoder 8 rotates together with the inner ring 12.

As shown in the longitudinal sectional view of FIG. 3A and the perspective view of FIG. 3B, the protective cover 1 according to the embodiment of the present invention is press-fitted into the outer ring 13 (see FIGS. 1 and 2). The first cylindrical portion 2, the second cylindrical portion 3 that is smaller in diameter than the first cylindrical portion 2 and connected to the edge of the first cylindrical portion 2, is connected to the edge of the second cylindrical portion 3, and is radially inward. An annular part 4 that extends, a third cylindrical part 5 that extends in the axial direction by connecting to the inner edge of the annular part 4, a disk part 6 that connects to the edge of the third cylindrical part 5, and the second cylindrical part 3 The disk portion 6 is formed with a recess 6A at the center thereof.
Here, the base portion (other than the seal body 7) of the protective cover 1 is pressed from an austenitic stainless steel plate material containing a certain amount (for example, about 1 to 4% by weight) of copper such as SUS304J1, SUS304J2, or SUSXM7. It is formed by processing.

Further, since the seal body 7 is an elastic body such as synthetic rubber, the airtightness between the protective cover 1 and the outer ring 13 can be improved. The seal body 7 is made of nitrile rubber as a rubber material having good oil resistance. (NBR), hydrogenated nitrile rubber (HNBR), acrylic rubber (ACM), ethylene / acrylic rubber (AEM), fluorine rubber (FKM, FPM), silicone rubber (VQM), etc. The above rubbers can be appropriately blended and used.
Furthermore, since the surface finish of the base material for the base portion of the protective cover 1 is a dull finish, it is easy to hold the processing oil during the press working, so that seizure during the drawing process is prevented and surface scratches are conspicuous. It is difficult and the appearance is good due to the matte effect on the surface, and the adhesiveness of the seal body 7 is improved.

As can be seen from the graph showing the change in the relative magnetic permeability according to the cold rolling ratio in FIG. 4, the relative magnetic permeability of SUS04 increases rapidly as the degree of work increases.
Therefore, when SUS04 is used as the plate material for the protective cover, depending on the degree of processing, the magnetic permeability after making the cup shape by pressing becomes larger and the magnetism becomes easier to magnetize than the magnetic permeability before pressing. Therefore, when the protective cover is used, the protective cover disturbs the magnetic field of the magnetic encoder 8, so that the detection accuracy of the rotational speed detecting device is lowered.
In addition, if the degree of processing is kept small, the degree of freedom in design becomes small, and there are cases where it is not possible to cope with a severe demand for improving the detection accuracy of the rotational speed detection device.
Furthermore, workability is poor because it is easy to work and harden by drawing in press working.

On the other hand, as can be seen from FIG. 4, when SUS304J2 or SUSXM7 is used, the relative magnetic permeability does not increase so much even if the degree of processing increases.
Therefore, even if the degree of processing is increased by forming the base portion of the protective cover 1 by pressing from an austenitic stainless steel plate material containing a certain amount of copper such as SUS304J2 or SUSXM7, the magnetic permeability does not increase. It is difficult to magnetize, and the protective cover 1 does not disturb the magnetic field of the magnetic encoder 8, so that the detection accuracy of the rotational speed detection device does not decrease.
In addition, since there is no restriction that the degree of processing cannot be increased as in the case of using SUS04 as a plate material for the protective cover, the degree of freedom in design is increased, and the demand for improving the detection accuracy of the rotational speed detection device is severe. Can also handle cases.
Furthermore, by forming the base portion of the protective cover 1 from a plate made of austenitic stainless steel containing a certain amount of copper by press working, it is difficult to work harden by drawing in press working and workability is improved.

DESCRIPTION OF SYMBOLS 1 Protective cover 2 1st cylindrical part 3 2nd cylindrical part 4 Ring part 5 3rd cylindrical part 6 Disk part 6A Indentation 7 Seal body 8 Magnetic encoder 9 Support member 9A Cylindrical part 9B Ring part 10 Sensor 11 Bearing apparatus 12 Inner ring 12A Inner ring raceway surface 13 Outer ring 13A Outer ring drive surface 14 Rolling element 15 Seal member

Claims (2)

An inner ring having an inner ring raceway surface formed on the outer peripheral surface, an outer ring having an outer ring raceway surface formed on the inner peripheral surface, and a bearing having a rolling element that rolls between the inner ring raceway surface and the outer ring raceway surface, the bearing A magnetic encoder that is fixed to the inner ring at one end in the axial direction and that has N poles and S poles alternately arranged in the circumferential direction at regular intervals, and a magnetic pole of the magnetic encoder that is fixed to the outer ring A cup-shaped protective cover press-fitted into the outer ring so as to cover the magnetic encoder and interposed between the magnetic encoder and the sensor. Because
A protective cover formed by pressing from a plate made of austenitic stainless steel containing a certain amount of copper. A bearing device comprising the protective cover according to claim 1.

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