JP2006336753A - Rolling bearing unit with sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To actualize construction for improving the detecting accuracy of a sensor 7 while preventing an increase in wear between a cage 5a and each rolling element 4. <P>SOLUTION: An area where the sensor 7 and an encoder 6 exist is encircled by a magnetic material cover 14 and a magnetic member 26 to prevent a magnetic flux existing outside from passing through the area. The cage 5a is formed of a synthetic resin as a non-magnetic material. As a result, there are no influences of the outside magnetic flux or the cage 5a on the detecting accuracy of the sensor 7. The cage 5a is not magnetized by the magnetic field of the encoder 6, thus preventing the occurrence of magnetic attraction between the cage 5a and each rolling element 4 to prevent an increase in wear. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an improvement in a rolling bearing unit with a sensor that supports a rotating shaft of an electric motor, an industrial machine, or the like and can detect the rotational speed of the rotating shaft.

  With recent advances in control technology, sensor-equipped rolling bearing units that incorporate sensors that detect various types of information on the rotating bodies that make up the rotating mechanisms of various mechanical devices such as electric motors and industrial machines have been used in the past. Are known. Such a sensor-equipped rolling bearing unit rotatably supports a rotating shaft that rotationally drives the rotating body and detects the rotational speed of the rotating shaft. As a result, the rotational speed and the like of various mechanical devices can be detected with a compact structure. As an application example of such a sensor-equipped rolling bearing unit, for example, it is conceivable to incorporate a rotation speed sensor into a deep groove type ball bearing that supports the rotation shaft of a normal induction motor. As a result, by detecting a change in the output rotation speed of the motor due to a load change and feeding back this change to the input voltage, the motor can maintain a constant output rotation speed with a compact structure regardless of the load change. Can be obtained.

  As the above-mentioned sensor-equipped rolling bearing unit, those having various structures are conventionally known. In particular, as described in, for example, Patent Documents 1 to 3, many structures using a change in magnetic flux are known. FIG. 4 shows the structure described in Patent Document 1 among them. The sensor-equipped rolling bearing unit 1 includes an outer ring 2 that is a stationary ring, an inner ring 3 that is a rotating ring, a plurality of rolling elements 4 and 4, a cage 5, an encoder 6, and a sensor 7. Of these, the outer ring 2 has an outer ring raceway 8 that is a stationary side raceway on the inner peripheral surface, and is fitted and fixed to a fixed part such as a housing and does not rotate during use. The inner ring 3 has an inner ring raceway 9 that is a rotation side raceway on the outer peripheral surface, and is fitted and fixed to a rotary shaft, and rotates when in use. The rolling elements 4 and 4 are made of bearing steel and are provided between the outer ring raceway 8 and the inner ring raceway 9 so as to be freely rollable. The retainer 5 is a corrugated press retainer made of a steel plate formed by combining a pair of retainer elements obtained by pressing a steel plate into a corrugated shape, and holds the rolling elements 4 and 4.

  The encoder 6 is supported by a holder 10 that is locked to the outer peripheral surface of one end (the right end in FIG. 4) of the inner ring 3. The holder 10 is formed by press forming a metal plate such as a steel plate. That is, the holder 10 has an annular part 11 and an outer peripheral edge of the annular part 11 in the axially outward direction (outside with respect to the axial direction is a direction toward the opposite side to the part where the rolling elements 4 and 4 are installed. And the inside means the opposite, and is the same in the entire specification and claims). Then, the inner peripheral edge of the annular ring portion 11 is locked in a groove provided on the outer peripheral surface of one end of the inner ring 3, and the encoder 6 formed in an annular shape is formed on the inner peripheral surface of the cylindrical portion 12. I support it. The groove for locking the inner peripheral edge of the circular ring portion 11 is incorporated in a normal (not equipped with a sensor) rolling bearing, and the seal lip of the seal ring on the one side (the side where the sensor 7 is installed in FIG. 4) is slid. It is a seal groove in contact. Thus, the encoder 6 fixed to the inner ring 3 via the holder 10 is magnetized in the radial direction, and N poles and S poles are arranged alternately at equal intervals in the circumferential direction. .

  The sensor 7 incorporates a sensor that changes characteristics in response to a change in magnetic flux, such as a Hall element or a magnetoresistive element. The sensor 7 is supported by a sensor housing 13 supported by the end portion of the outer ring 2, and the detection portion is opposed to the detection portion of the encoder 6. The sensor housing 13 includes a cover 14 made of a magnetic metal plate such as a mild steel plate such as SPCC, and a synthetic resin holding ring 15 held inside the cover 14. Of these, the cover 14 has a crank-shaped cross section and is formed in an annular shape as a whole, and holds the fitting cylinder portion 17 on the outer peripheral edge portion of the abutting plate portion 16 formed near the outer diameter portion on the inner peripheral edge portion. Each part 18 is formed. Of these, the fitting tube portion 17 is externally fitted to the small diameter portion 19 formed on the outer peripheral surface of the end portion of the outer ring 2 by an interference fit, and the tip end portion of the fitting tube portion 17 is attached to the outer ring 2. The outer peripheral surface is caulked to a stepped portion 20 formed on the inner side in the axial direction from the small diameter portion 19. Thus, the cover 14 is coupled and fixed to the outer ring 2 in a state where the abutting plate portion 16 is abutted against the end face of the outer ring 2.

  The holding portion 18 has a substantially L-shaped cross section and is formed in an annular shape as a whole. The holding ring 15 is held and fixed in the holding portion 18. That is, the locking projections 21 provided in the circumferential direction of the holding ring 15 so as to protrude outward in the axial direction are provided with the locking holes provided in the circumferential direction of the holding portion 18 at a plurality of positions in the circumferential direction. The parts 22 are respectively locked. Thereby, the holding ring 15 is held and fixed in the holding portion 18. In the holding ring 15, the sensor 7 is embedded and supported so as to oppose the inner peripheral surface, which is the detected portion of the encoder 6, in the radial direction. For this purpose, a recess 23 that is recessed outward in the axial direction is formed on the inner surface of the holding ring 15 over the entire circumference. Then, the encoder 6 is caused to enter the recess 23, and a part of the upper surface of the sensor 7 is exposed to a part of the inner surface of the recess 23, so that the inner peripheral surface of the encoder 6 and the upper surface of the sensor 7 are exposed. Some are facing each other. Therefore, a part of the upper surface of the sensor 7 becomes the above-described detection unit.

  The holding ring 15 supports a substrate 24. The substrate 24 has a processing circuit for converting the characteristic change of the sensor 7 into an output signal. The holding ring 24 is locked to a locking projection 21 formed on the holding ring 15. 15 is fixed to the outer surface. Further, a harness 25 for taking out a detection signal of the sensor 7 is connected to a part of the substrate 24, and the harness 25 is led out from a part of the sensor housing 13 to the outside.

  In the case of the structure shown in FIG. 4, the magnetic member 26 formed in a cylindrical shape is fixed to the inner peripheral surface of the holding ring 15. The magnetic member 26 has, for example, a structure having magnetism by mixing iron powder, magnetic powder, or the like into synthetic resin. Then, it is fitted and fixed to the inner peripheral surface of the holding ring 15. Thus, the periphery of the portion where the sensor 7 and the encoder 6 are present except for the inner side in the axial direction is surrounded by the cover 14 made of a magnetic metal plate and the magnetic member 26.

  The sensor-equipped rolling bearing unit 1 configured as described above is used, for example, to rotatably support a rotating shaft such as a motor and to detect the rotational speed of the rotating shaft. For this purpose, the outer ring 2 is fitted and fixed to a fixed part such as a housing, and the inner ring 3 is fitted and fixed to the rotating shaft. Thereby, this rotating shaft can be rotatably supported with respect to the fixed portion. When the inner ring 3 rotates together with the rotating shaft, the encoder 6 supported on the outer peripheral surface of one end of the inner ring 3 via the holder 10 also rotates. As the encoder 6 rotates, the direction of the magnetic flux flowing in the sensor 7 changes alternately. The characteristics of the sensor 7 change in response to changes in the magnetic flux flowing through the sensor 7, and the output signal of the sensor 7 changes. Since the frequency at which the output signal changes is proportional to the rotational speed of the inner ring 3, the rotational speed of the inner ring 3 can be known by sending this output signal to a controller (not shown) via the harness 25.

  In the case of the sensor-equipped rolling bearing unit 1, the periphery of the portion where the sensor 7 and the encoder 6 exist except for the inner side in the axial direction is surrounded by a magnetic metal plate cover 14 and a magnetic member 26. . For this reason, it is possible to prevent an external magnetic flux other than the magnetic flux of the encoder 6 such as a magnetic flux leaking from the motor from passing through a portion where the sensor 7 and the encoder 6 exist. That is, the external magnetic flux that tries to pass through the part where the sensor 7 and the encoder 6 are present flows along the cover 14 and the magnetic member 26 and does not reach this part. As a result, the magnetic flux flowing through the sensor 7 is only the magnetic flux generated by the encoder 6. Therefore, the malfunction of the sensor 7 due to the external magnetic flux can be prevented and the change in the magnetic flux of the encoder 6 can be detected more reliably, so that the accuracy of rotational speed detection can be improved.

  As described above, the sensor-equipped rolling bearing unit 1 shown in FIG. 4 can improve the accuracy of rotational speed detection with a structure that can be reduced in size, but in response to the recent demand for higher detection accuracy. It may not be able to respond sufficiently. That is, in the case of the sensor-equipped rolling bearing unit 1, the cage 5 that holds the rolling elements 4 and 4 is made of a steel plate having magnetism, and therefore the cage 5 rotates together with the rolling bodies 4 and 4. The magnetic field generated by the encoder 6 may be disturbed. Specifically, since the cage 5 is a corrugated press cage, a part of the cage 5 (portion for holding the rolling elements 4 and 4) is close to the encoder 6, and the cage The distance from the encoder 6 is increased in the other part of 5 (the part between the rolling elements 4 and 4). For this reason, due to the rotation of the cage 5, the magnetic material approaches or moves away from the encoder 6, and the magnetic field of the encoder 6 is disturbed. Moreover, when the axial dimension of the sensor-equipped rolling bearing unit 1 is reduced in accordance with the recent demand for downsizing of the apparatus, the distance between the encoder 6 and the rolling elements 4 and 4 becomes closer. Since the rolling elements 4 and 4 are made of bearing steel as described above, the revolution of the rolling elements 4 and 4 may affect the magnetic field of the encoder 6. As described above, when the cage 5 or the rolling elements 4 and 4 are made of a magnetic material, the magnetic field of the encoder 6 may be disturbed, and an error may occur in detection by the sensor 7.

  As described above, when the cage 5 is made of a magnetic material, the acoustic life of the sensor-equipped rolling bearing unit 1 or the life until breakage tends to be shortened. That is, since the encoder 6 fixed to the inner ring 3 is constituted by a magnet, the cage 5 and the rolling elements 4 and 4 that are magnetic materials are excited in the magnetic field of the encoder 6, and these cages are excited. Magnetic attraction force is generated between 5 and the rolling elements 4 and 4. As a result, wear between the inner side surface of each pocket 27 of the cage 5 and the rolling surfaces of the rolling elements 4 and 4 held in the pockets 27 increases. Since the inner surface of each pocket 27 and the rolling surface of each of the rolling elements 4 and 4 are in sliding contact, a certain amount of wear is allowed. However, as described above, if a magnetic attractive force is generated between the inner surface of each of the pockets 27 and the rolling surface of each of the rolling elements 4, 4, the amount of wear due to the sliding contact increases more than expected. . As a result, wear powder increases, the grease in the sensor-equipped rolling bearing unit 1 deteriorates early, and the bearing is easily damaged. And compared with a normal rolling bearing without a sensor, noise is likely to increase early (acoustic life is reduced) and is likely to be damaged early.

  The phenomenon as described above becomes more prominent as the magnetic force of the encoder 6 becomes stronger. Examples of the magnet used as the encoder 6 include casting magnets such as alnico magnets, rare earth magnets such as ferrite magnets and neodymium-boron. Of these, the rare earth magnet has the strongest magnetic force. However, in recent years, a magnet having a strong magnetic force such as this rare earth magnet is often used as the magnet of the encoder 6 in order to further improve the detection accuracy of the sensor 7. I came. Therefore, as described above, the detection accuracy of the sensor 7 is reduced due to the cage 5 and the rolling elements 4 and 4 disturbing the magnetic field, and the wear increases due to the magnetization of the cage 5 and the rolling elements 4 and 4. But it is getting more attention.

  For example, as described in Patent Documents 2 and 3, if the cage is made of synthetic resin, the above-described problem does not occur. However, in the case of the structures described in Patent Documents 2 to 3, the cage is not made of a synthetic resin in consideration of an increase in wear due to magnetization of the cage and the rolling element. Further, since the influence of the external magnetic flux is not taken into consideration, the portion where the sensor and the encoder exist is not surrounded by a magnetic material. Therefore, in the case of the structures of Patent Documents 2 to 3, it is difficult to further improve the detection accuracy of the sensor.

  In the case of the structure shown in FIG. 4, the sensor 7 side of the annular space 28 that exists between the inner peripheral surface of the outer ring 2 and the outer peripheral surface of the inner ring 3 and in which the rolling elements 4 and 4 exist (FIG. 4). The right side of the opening is not provided with a seal ring. That is, the encoder 6 is installed on the outer peripheral surface of the inner ring 3 on the sensor 7 side. As shown in FIG. 4, the cage 5 is a corrugated press cage, and the rolling elements 4 and 4 are clamped from both sides in the axial direction by a pair of cage elements. For this reason, it is difficult to secure a space for providing a seal ring at the opening of the annular space 28 on the sensor 7 side. Therefore, in the case of the structure shown in FIG. 4, no seal ring is provided in the opening on the sensor 7 side.

  On the other hand, the annular space 28 is filled with grease to lubricate between the rolling surfaces of the rolling elements 4, 4 and the outer ring raceway 8 and the inner ring raceway 9. For this reason, a seal ring 29 is provided at the opening on the opposite side of the annular space 28 from the sensor 7 (left side in FIG. 4) to prevent the grease from leaking out from the opening and to prevent foreign matter from entering from the outside. Prevent entry. On the other hand, since the opening on the sensor 7 side of the annular space 28 is covered by the sensor housing 13 that supports the sensor 7, foreign matter may enter from the outside or grease may leak out. The degree can be prevented. However, the structure shown in FIG. 4 may not sufficiently prevent the leakage of grease.

  That is, the grease filled in the annular space 28 is blocked by the holder 10 to which the encoder 6 is fixed. However, since the holder 10 rotates together with the inner ring 3, the grease attached to the holder 10 is centrifuged. Force acts. Then, the grease swung away radially outward by the centrifugal force may leak to the outside through a gap between the holding ring 15 that holds the sensor 7 and the encoder 6. In this way, when the grease filled in the annular space 28 leaks to the outside, there is not enough grease to lubricate between the rolling surfaces of the rolling elements 4 and 4 and the outer ring raceway 8 and the inner ring raceway 9. However, seizure occurs early.

JP 2004-218684 A Japanese Patent Laid-Open No. 11-326353 JP 2000-346673 A

  The rolling bearing unit with sensor of the present invention realizes a structure that can further improve the detection accuracy of the sensor and prevent an increase in wear between the cage and the rolling element in view of the above-described circumstances. Invented accordingly.

The sensor-equipped rolling bearing unit of the present invention includes a stationary wheel, a rotating wheel, a plurality of rolling elements, a cage, an encoder, and a sensor, as in the conventional structure shown in FIG.
Among these, the stationary wheel has a stationary side track and does not rotate during use.
The rotating wheel has a rotation side track and rotates when in use.
Further, each of the rolling elements is provided between the stationary track and the rotating track so as to freely roll.
Moreover, the said holder | retainer hold | maintains each of these rolling elements.
The encoder is supported at the end of the rotating wheel, and alternately changes the magnetic characteristics of the surface to be detected in the circumferential direction.
The sensor is supported on the end of the stationary wheel. In addition, it has a detection section facing the detected section of the encoder, and detects a change in magnetic flux accompanying the rotation of the encoder.
In particular, in the rolling bearing unit with sensor according to the present invention, the magnetic flux existing outside passes through this part by enclosing at least a part of the part where the sensor and the encoder exist with a member made of magnetic material. I try not to. In addition, the cage is made of a nonmagnetic material.

  In the case of the rolling bearing unit with a sensor of the present invention configured as described above, the detection accuracy by the sensor can be further improved, and an increase in the amount of wear can be prevented between the cage and the rolling element. That is, since the magnetic flux existing outside does not pass through the portion where the sensor and the encoder exist, the external magnetic flux does not affect the detection accuracy of the sensor. Further, since the cage is made of a non-magnetic material, this cage does not affect the detection accuracy of the sensor. Further, since the cage is not magnetized, it is possible to prevent a magnetic attractive force from being generated between the cage and each rolling element. For this reason, the amount of wear does not increase between these cages and each rolling element. As a result, it is possible to prevent a decrease in acoustic life and life until breakage.

In order to carry out the present invention, preferably, the magnet incorporated in the encoder or sensor is a rare earth magnet.
If comprised in this way, it will become easier to detect the change of magnetic flux, and the detection accuracy of a sensor can be improved more. Even if such a rare earth magnet having a strong magnetic force is used, the retainer is not magnetized, so that it is possible to prevent an increase in wear between the retainer and each rolling element. More preferably, as described in claim 3, each rolling element is made of a non-magnetic material, for example, ceramic.
If comprised in this way, since neither a holder | retainer nor each rolling element will affect the detection accuracy of a sensor, the detection accuracy of this sensor can be improved more.

More preferably, as described in claim 4, a sealing plate is provided between the encoder supported at the end of the rotating wheel and the space where each rolling element exists.
If comprised in this way, most of the grease which goes to the opening part by the side of a sensor among the grease enclosed in the bearing will be dammed by the sealing board. For this reason, the grease is difficult to leak out from the opening on the sensor side.
In order to carry out the invention described in claim 4, preferably, as described in claim 5, the cage is a crown type cage having a rim portion only on one side in the axial direction. Place on the opposite side of the sensor.
If comprised in this way, the space which provides a sealing board on the sensor side of the space filled with the grease in a bearing is securable. For this reason, it is not necessary to increase the axial dimension of the rolling bearing unit with sensor in order to provide this sealing plate. Therefore, even if a sealing plate is provided on the sensor side, the rolling bearing unit with sensor can be downsized.
More preferably, as described in claim 6, the sealing plate is locked in a locking groove formed on the peripheral surface of the end portion of the stationary ring.
If this groove is a normal (not equipped with a sensor) rolling bearing that has been used to lock a sealing device such as a seal ring, a new groove is formed to lock the sealing plate. There is no need to do.
More preferably, as described in claim 7, the sealing plate is made of a nonmagnetic material.
If comprised in this way, it can prevent that a sealing board influences the detection accuracy of a sensor. That is, for example, when a structure in which an elastic material is attached to a metal cored bar is used as the sealing plate, the cored bar may disturb the magnetic field detected by the sensor. On the other hand, if the sealing plate is made of a nonmagnetic material, this is not the case.
Even if the sealing plate is made of a magnetic material, it is considered that the possibility of disturbing the magnetic field is low. That is, the sealing plate is fixed to the stationary ring, and the cross-sectional shape is the same over the entire circumference. Therefore, even when the encoder rotates relatively, the distance between the sealing plate and the encoder does not change in the circumferential direction, and the presence of the sealing plate is unlikely to disturb the magnetic field. However, the distance between the encoder and the sealing plate is not necessarily uniform in the circumferential direction (for example, due to the deflection of the encoder). For this reason, when the sealing plate is made of a magnetic material, a change in the distance between the sealing plate and the encoder may disturb the magnetic field detected by the sensor.

  FIG. 1 shows a first embodiment of the present invention corresponding to claims 1 and 2. The feature of the present invention is that the sensor 7 and the encoder 6 are present in order to further improve the detection accuracy by the sensor 7 and prevent the wear between the cage 5a and each rolling element 4 from increasing. The external magnetic flux is prevented from passing through the portion to be made, and the cage 5a is made of a nonmagnetic material. Since the structure and operation of the other parts are the same as those of the conventional structure shown in FIG. 4, the overlapping description will be simplified or omitted, and the following description will focus on the characteristic parts of the present invention.

  The sensor-equipped rolling bearing unit 1a according to the present embodiment is similar to the structure shown in FIG. 4 described above. The encoder 6 is connected to the outer peripheral surface of one end portion (right end portion in FIG. I support it. The encoder 6 is magnetized in the radial direction, and N poles and S poles are alternately arranged at equal intervals in the circumferential direction. Further, as the magnet constituting the encoder 6, for example, a rare earth magnet having strong magnetism such as neodymium-boron is used. Further, the sensor 7 is provided in a sensor housing 13 supported on one end side of the outer ring 2 which is a stationary ring through a holding ring 15 made of synthetic resin. The sensor 7 includes a Hall element, a magnetoresistive element, or the like that changes its characteristics in response to a change in magnetic flux, but a plurality of such elements can also be incorporated. That is, if a plurality of elements are arranged at positions separated from each other in the circumferential direction, not only the rotation speed of the inner ring 3 but also the rotation direction can be detected. A plurality of the sensors 7 themselves may be arranged in the circumferential direction of the holding ring 15.

  In the case of this embodiment, the encoder 6 is constituted by a rare earth magnet, and a change in the magnetic flux of the encoder 6 is detected by the sensor 7. However, for example, the sensor may include a permanent magnet, a Hall element, a magnetoresistive element, and the like, and a structure in which notches, through holes, and the like are formed at a plurality of positions in the circumferential direction of an encoder made of a magnetic material. In this case, the permanent magnet incorporated in the sensor is a rare earth magnet. Further, a passive structure may be used regardless of such an active structure. In short, any structure may be used as long as the output of the sensor changes as the magnetic flux changes. On the other hand, a structure that does not use a magnet for detecting the rotational speed, such as a photoelectric type or an eddy current type, is out of the technical scope of the present invention.

  Also in the present embodiment, similarly to the structure of FIG. 4 described above, the periphery of the portion where the sensor 7 and the encoder 6 are present except for the inside in the axial direction is covered with the magnetic material cover 14 and the magnetic member. 26. That is, the cover 14 constituting the sensor housing 13 that supports the sensor 7 is formed of a magnetic metal plate such as a mild steel plate, and the axially outward and radial directions of the portion where the sensor 7 and the encoder 6 are present. It covers the outside. In addition, a synthetic resin magnetic member 26 mixed with a magnetic member such as iron powder ferrite powder is fitted and fixed to the inner peripheral surface of the holding ring 15 that embeds and supports the sensor 7. . For this reason, the magnetic member 26 is present radially inward of the portion where the sensor 7 and the encoder 6 are present. Thus, in the case of the present embodiment, the axially outer side and the radial outer side of the portion where the sensor 7 and the encoder 6 exist are covered with the cover 14 and the inner side in the axial direction is covered with the magnetic member 26, respectively. The external magnetic flux is prevented from passing through the portion where the sensor 7 and the encoder 6 exist.

  The magnetic member 26 may be a rubber mixed with magnetic powder or fiber, or a plate material (steel plate or the like) made of a magnetic material, in addition to a synthetic resin mixed with a magnetic member. Moreover, it is good also as a structure which applies the coating material and adhesive agent which mixed the powder and fiber which have magnetism to the internal peripheral surface of the said holding | maintenance ring 15. FIG. Furthermore, a synthetic resin mixed with magnetic powder or fiber may be integrally formed with the synthetic resin constituting the retaining ring 15 when the retaining ring 15 is formed. In short, it is only necessary that a magnetic shielding layer having magnetism exists on the inner peripheral surface of the retaining ring 15.

  In this embodiment, the cage 5a is made of a synthetic resin that is a nonmagnetic material. That is, this cage 5a is formed by forming a synthetic resin such as polyamide 66, polyamide 46, polyacetal, polyphenylene sulfide, polyether ether ketone, or the like, reinforced by containing 10 to 30% by weight of glass fiber in a crown shape. Yes. In the case of the present embodiment, the cage 5a may be made of a nonmagnetic material and is not limited to a synthetic resin. Further, the shape of the cage 5a is not limited to the crown shape. For example, it may be a machined type cage in which synthetic resin is formed in a cylindrical shape and holes for forming pockets are formed at a plurality of locations in the circumferential direction.

  In the case of the present embodiment, in order to prevent the rim portion 30 constituting the crown-shaped cage 5a from interfering with the holder 10 supporting the encoder 6, the rim portion 30 is placed on the side opposite to the sensor 7 ( It is arranged on the left side of FIG. However, it is preferable to arrange the rim portion 30 on the sensor 7 side (the right side in FIG. 1) as long as it does not interfere with the holder 10. If comprised in this way, it will become difficult for the grease which exists in each pocket of the said holder | retainer 5a to go to the said sensor 7 side, and it can prevent that a lot of grease leaks from this sensor 7 side. In addition, since the seal ring 29 is provided in the opening part on the opposite side to the sensor 7 of the annular space 28 in which each rolling element 4 exists, grease does not leak from this opening part.

  In the case of the rolling bearing unit with sensor 1a of the present embodiment configured as described above, the detection accuracy by the sensor 7 can be further improved, and the wear between the cage 5a and each rolling element 4 can be improved. Can be prevented. That is, since the periphery of the portion where the sensor 7 and the encoder 6 are present except for the inside in the axial direction is surrounded by the cover 14 and the magnetic member 26 which are members made of a magnetic material, the external magnetic flux is applied to the sensor 7. This does not affect the detection accuracy. More specifically, the external magnetic flux leaked from the motor or the like flows (bypassed) through the cover 14 and the magnetic member 26 and hardly reaches the sensor 7. Therefore, the external magnetic flux does not affect the detection accuracy of the sensor 7. Further, since the cage 5a is made of a synthetic resin which is a non-magnetic material, the cage 5a does not affect the detection accuracy of the sensor 7. Therefore, it is possible to detect the rotational speed and the like by the sensor 7 with higher accuracy.

  In addition, as described in claim 3, even if each of the rolling elements 4 is made of a non-magnetic material, the detection accuracy of the sensor can be further improved. That is, if each rolling element 4 is made of ceramics, for example, the magnetic field of the encoder 6 is not disturbed by each rolling element 4. Further, when the axial dimension of the rolling bearing unit with sensor 1a is reduced in order to reduce the size of the apparatus, the distance between the encoder 6 and each rolling element 4 becomes small, and the existence of each rolling element 4 exists. However, this tends to affect the magnetic field of the encoder 6. Therefore, if each of these rolling elements 4 is made of a non-magnetic material with such a structure, the axial dimension of the sensor-equipped rolling bearing unit 1a can be reduced without reducing the detection accuracy of the sensor 7.

  Furthermore, in the case of the present embodiment, since the cage 5a is made of a synthetic resin, the cage 5a is not magnetized by the magnetic force of the encoder 6, and the cage 5a and each of the rolling elements 4 are not magnetized. It is possible to prevent a magnetic attractive force from being generated between them. For this reason, it is possible to prevent the wear between the inner side surface of each pocket of the cage 5a and the rolling surface of each rolling element 4 from increasing. As a result, it is possible to prevent the acoustic life of the sensor-equipped rolling bearing unit 1a and the life until breakage from being reduced. In particular, as in the structure of the present embodiment, in order to further improve the detection accuracy of the sensor 7, when the encoder 6 is made of a strong magnetic rare earth magnet, the cage 5a and the rolling elements 4 are used. The effect of preventing an increase in wear between the two can be obtained more remarkably.

  FIG. 2 shows a second embodiment of the present invention corresponding to claims 1, 2, 4 to 6. In the case of the present embodiment, at the opening on the sensor 7 side (right side in FIG. 2) of the annular space 28 of the rolling bearing unit with sensor 1b, between the holder 10 holding the encoder 6 and each of the rolling elements 4, 4. A sealing plate 31 is provided. For this purpose, the cage 5a that holds the rolling elements 4 and 4 is used as a crown-type cage, and the rim portion 30 that constitutes the cage 5a is arranged on the side opposite to the sensor 7 (left side in FIG. 2). is doing. In other words, the opening side of each pocket 27 formed at a plurality of locations in the circumferential direction of the cage 5a is the side where the sensor 7 is present. Accordingly, since a space in which the sealing plate 31 can be installed can be secured between the holder 10 and the rolling elements 4 and 4, the axial dimension of the sensor-equipped rolling bearing unit 1b is increased to provide the sealing plate 31. do not have to. As a result, even if the sealing plate 31 is provided on the sensor 7 side, the sensor-equipped rolling bearing unit 1b can be reduced in size.

  The sealing plate 31 is formed by forming a metal plate such as a stainless steel plate into an annular shape, and the outer peripheral edge is locked to a locking groove 32 formed on the inner peripheral surface of the end of the outer ring 2 and the inner peripheral edge portion. Is opposed to the outer peripheral surface of the end portion of the inner ring 3. The locking groove 32 is a normal (not equipped with a sensor) rolling bearing, and a groove that has locked a sealing device such as a seal ring is used as it is. For this reason, it is not necessary to newly process a groove for locking the sealing plate 31. In the case of this embodiment configured as described above, leakage of the grease filled in the annular space 28 can be further prevented. That is, most of the grease that goes to the opening on the sensor 7 side is blocked by the sealing plate 31, so that it is difficult for the grease to leak out from the opening on the sensor 7 side. Other structures and operations are the same as those of the first embodiment.

  FIG. 3 shows Embodiment 3 of the present invention corresponding to claims 1, 2, 4 to 7. In the case of the present embodiment, the sealing plate 31a provided at the opening on the sensor 7 side (the right side in FIG. 3) of the annular space 28 of the sensor-equipped rolling bearing unit 1c is made of a synthetic resin that is a nonmagnetic material. For this reason, this sealing plate 31a can be prevented from affecting the detection accuracy of the sensor 7, and the detection accuracy by the sensor 7 can be further improved. Other structures and operations are the same as those in the second embodiment.

  In each of the above-described embodiments, the case where the present invention is applied to a structure using a ball bearing as a rolling bearing unit with a sensor has been described. However, the present invention can also be applied to a structure using a roller bearing. is there. In each of the above-described embodiments, the case where the present invention is applied to the inner ring rotating structure has been described. However, the present invention can also be applied to the outer ring rotating structure. In this case, the encoder is supported on the outer ring and the sensor is supported and fixed on the inner ring.

FIG. 2 is a half sectional view showing Example 1 of the present invention. Sectional drawing which similarly shows Example 2. FIG. Sectional drawing which similarly shows Example 3. FIG. Sectional drawing which shows an example of the conventional structure of the rolling bearing unit with a sensor used as the object of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 1a, 1b, 1c Rolling bearing unit with a sensor 2 Outer ring 3 Inner ring 4 Rolling body 5, 5a Cage 6 Encoder 7 Sensor 8 Outer ring track 9 Inner ring track 10 Holder 11 Circular ring part 12 Cylindrical part 13 Sensor housing 14 Cover 15 Holding Ring 16 Abutting part 17 Fitting cylinder part 18 Holding part 19 Small diameter part 20 Step part 21 Locking convex part 22 Locking hole part 23 Recessed part 24 Substrate 25 Harness 26 Magnetic member 27 Pocket 28 Annular space 29 Seal ring 30 Rim part 31 31a Sealing plate 32 Locking groove

Claims (7)

  A stationary wheel that has a stationary track and does not rotate during use, a rotating wheel that has a rotating track and rotates during use, and a plurality of rolling wheels provided between the stationary track and the rotating track. A rolling element, a cage that holds each of the rolling elements, an encoder that is supported by an end of the rotating wheel, and that alternately changes the magnetic characteristics of the detected surface in the circumferential direction; and an end of the stationary ring In a sensor-equipped rolling bearing unit comprising a sensor that is supported by a sensor and has a detector that faces a detected part of the encoder and that detects a change in magnetic flux associated with the rotation of the encoder, the sensor and the encoder By enclosing at least a part of the part where the magnetic material is surrounded by a member made of a magnetic material, the magnetic flux existing outside is prevented from passing through this part, and the cage is made of a non-magnetic material. Rolling with sensor Receiving unit.   The rolling bearing unit with a sensor according to claim 1, wherein a magnet incorporated in the encoder or sensor is a rare earth magnet.   The rolling bearing unit with a sensor according to claim 1 or 2, wherein each rolling element is made of a nonmagnetic material.   The rolling bearing unit with a sensor according to any one of claims 1 to 3, wherein a sealing plate is provided between an encoder supported at an end of the rotating wheel and a space in which each rolling element exists.   The rolling bearing unit with a sensor according to claim 4, wherein the cage is a crown type cage having a rim portion on only one side in the axial direction, and the rim portion is disposed on the side opposite to the sensor.   The rolling bearing unit with a sensor according to claim 4 or 5, wherein the sealing plate is locked in a locking groove formed on the peripheral surface of the end portion of the stationary ring. The rolling bearing unit with a sensor according to any one of claims 4 to 6, wherein the sealing plate is made of a nonmagnetic material.

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