JP2004251316A - Rolling bearing with rotation sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent extraction of a magnetic encoder fitted to an outer ring in an outer ring rotating type rolling bearing with a rotation sensor, and to prevent creep between the outer ring of a bearing and a bearing housing to cause disconnection of a sensor cable. <P>SOLUTION: A core 7 of a magnetic encoder 8 is press-fitted in an outer ring 1. The core 7 is fixed to an end face of the outer ring 1 at a welded part 9 by laser beam welding or electronic beam welding. Viscous lubricant 26 is sealed between the outer ring and a bearing housing 23 by using two ring-shaped annular bodies 25. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a bearing with a rotation sensor, and more particularly to a rolling bearing with a rotation sensor.
[0002]
[Prior art]
2. Description of the Related Art It is conventionally known to mount a rotation sensor including a magnetic encoder and a magnetic sensor on a bearing in order to detect the number of rotations of various types of rotating devices. When a rolling bearing is used as a bearing, generally, the bearing is used as an inner ring rotating type, and an annular magnetic encoder is mounted on the rotating inner ring, and a clearance required for the magnetic encoder is provided on the fixed outer ring. Then, a magnetic sensor is attached (see Patent Document 1 or 2).
[0003]
As means for fixing the magnetic encoder to the inner ring, when mounted on a standard bearing, the space in the width direction is extremely narrow, and in order to ensure concentricity, the core metal is pressed into the outer diameter surface of the inner ring. In this case, a fixing means is employed. In this case, since the shaft is penetrated through the inner surface of the inner ring, even if a repeated load is applied, the magnetic encoder is backed up by the shaft via the inner ring, so there is no risk of deformation, and therefore, the magnetic encoder is moved from the inner ring. There is no risk of coming off.
[0004]
Patent Document 1 describes that a metal support member (core metal) on the magnetic sensor side is welded to an end surface of an outer ring that is a fixed side.
[0005]
On the other hand, as a general technology of a bearing, it has been conventionally known that a so-called creep occurs when a rotational load is applied to the outer ring while the outer ring of the bearing is fitted to the bearing box with a positive clearance. As an effective means for preventing the creep, two ring-shaped rings are interposed between the outer peripheral surface of the outer ring and the bearing housing, and a viscous lubrication such as grease is provided in a sealed space between the two ring-shaped rings. A bearing support structure to which an agent is attached is known (see Patent Document 3). This structure uses a thin film of high-pressure fluid of viscous lubricant between two ring-shaped rings when a load is applied to the outer ring and the outer ring is eccentric in the direction of the load with respect to the bearing box during use of the bearing. Is formed, and the outer ring is supported via the fluid thin film to prevent creep. The above-described bearing support structure is a prior art of the invention of this application as described later.
[0006]
[Patent Document 1]
Japanese Patent Application Laid-Open No. Hei 10-300516 (FIG. 3, paragraph 0020)
[Patent Document 2]
JP-A-2002-295465 (FIG. 1, paragraph 0003)
[Patent Document 3]
Japanese Utility Model Publication No. 52-8896 (FIG. 6 and description of the embodiment)
[0007]
[Problems to be solved by the invention]
Contrary to the case of Patent Documents 1 and 2, in the case of a bearing with a rotation sensor of an outer ring rotation type in which the inner ring is a fixed side and the outer ring is a rotation side, the magnetic encoder is mounted on the outer ring side, and the magnetic sensor is the inner ring. Mounted on the side. In this case, if the magnetic encoder is mounted by press-fitting and fixing to the inner diameter surface of the outer ring in the same manner as the conventional mounting means, there is a possibility that a breakage may occur due to a shock at the time of assembling the bearing or a repeated bending deformation to the outer ring at the time of load application. There is. Further, the space is too small to use other fixing methods such as caulking for preventing falling off, and it is impossible to use them together.
[0008]
The structure in which the above-described repeated bending deformation occurs is as follows. That is, when a radially inward load is applied to the outer diameter surface of the rotating outer ring, the inward elastic deformation of the outer ring when the load acts on the rolling element portion is small because the rolling element supports the inner ring. However, when a load acts between the rolling elements, the inward elastic deformation of the outer ring becomes larger than that of the former. When the outer ring rotates in such a state, the outer ring repeatedly undergoes bending deformation. Due to such repeated bending deformation, the magnetic encoder press-fitted with a required interference may come off in the axial direction. Incidentally, in the case of inner ring rotation, such a phenomenon does not occur because the shaft is fitted on the inner ring side.
[0009]
As described above, in a bearing with a rotation sensor used under conditions of outer ring rotation and outer ring rotation load, if the magnetic encoder attached to the outer ring is simply press-fitted and fixed to the outer ring, there is a risk that the magnetic encoder will come off during assembly or use. In view of the above, it is a first object of the present invention to provide a bearing with a rotation sensor of an outer ring rotation type, in which a magnetic encoder is securely attached to an outer ring and is prevented from coming off.
[0010]
On the other hand, in the case of bearings with rotation sensors used under the conditions of outer ring rotation and outer ring rotation load, in order to avoid disconnection of the cable that outputs the signal of the magnetic sensor wired between the inner ring and the shaft, the two are relatively Cannot be adopted. For this reason, the shaft and the inner ring must be tightly fitted, but from the viewpoint of preventing creep, the outer ring must also be tightly fitted to the bearing housing. However, it is difficult to fit the inner and outer rings tightly because of the incorporation of the bearing.
[0011]
Therefore, it is a second object of the present invention to provide a bearing with a rotation sensor that has a structure that prevents disconnection of a cable and is easy to assemble, in addition to the first problem described above.
[0012]
[Means for Solving the Problems]
In order to solve the first problem described above, the present invention provides an encoder which is mounted on an outer ring via a metal core, a sensor facing the encoder with a required gap is mounted on an inner ring, and the inner ring is fixed on a fixed side. In a bearing with a rotation sensor of an outer ring rotation type using the outer ring as a rotation side, a structure in which a core of the encoder is press-fitted to the outer ring and the core is fixed to the outer ring by laser welding or electron beam welding. Adopted.
[0013]
As a welding method of the core metal and the outer ring, the core metal (for example, SPCC) and the outer ring (for example, SUJ2) are made of different materials, the magnetic encoder uses a rubber magnet, is weak to heat, and the outer ring is hardened. Laser welding or electron beam welding is effective because it is made of a material that is very fragile.
[0014]
Further, it is desirable that the welding position is on or near the center line of the compressive stress and the tensile stress of the bending of the outer ring. This is to reduce the load on the weld. Welding is performed all around the core or at several points.
[0015]
In order to achieve the second object, the present invention provides the above-mentioned bearing with a rotation sensor, wherein at least two ring-shaped annular bodies are interposed between the outer peripheral surface of the outer ring and the bearing box, The structure employs a viscous lubricant adhered between the annular rings. According to this configuration, the outer ring is prevented from creeping, and the outer ring and the bearing box are loosely fitted, so that even when the shaft and the inner ring are tightly fitted, the outer ring side assembly may be hindered. Absent.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The first embodiment shown in FIGS. 1 and 2 is a rolling bearing of an outer ring rotating type, which is a rolling element which is held at regular intervals by a retainer 5 between respective raceway grooves 3 and 4 of an outer ring 1 and an inner ring 2. The ball 6 is interposed.
[0017]
A magnetic encoder 8 supported by an annular metal core 7 is attached to one end surface of the outer race 1. The magnetic encoder 8 is made of a rubber magnet, and is magnetized alternately at different intervals in the circumferential direction. The metal core 7 includes a small-diameter cylindrical portion 7a, a disk portion 7b, and a large-diameter cylindrical portion 7c. The small-diameter cylindrical portion 7a is press-fitted into the inner diameter end of the outer ring 1 and the disk portion 7b is brought into contact with the end surface of the outer ring 1. Mounted. The large-diameter cylindrical portion 7c is located on the neutral line N of the outer ring 1 in bending deformation. The bent portion between the disk portion 7b and the large-diameter cylindrical portion 7c is on the neutral line N, and welding is performed at the neutral line N (see the welded portion 9). As a preferable welding method, laser welding or electron beam welding can be adopted. As shown in FIG. 2, the welding position shows a case where welding is performed at several points in a point shape, but may be performed on the entire circumference.
[0018]
Since the core metal 7 has the small-diameter cylindrical portion 7a and the disk portion 7b, it is positioned at the time of welding as compared with the case where the large-diameter cylindrical portion 7c is directly welded, can be welded with high accuracy, and is deformed (falls) due to welding. Nor. In addition, by setting the position of the weld 9 on the neutral line N, the bending of the outer ring 1 at the weld 9 is theoretically zero, and no repeated shearing force acts on the weld 9.
[0019]
In the inner ring 2 on the fixed side, an annular housing core 11 is attached to the end outer diameter surface on the magnetic encoder 8 side, and the housing core 11 is integrally provided with a sensor housing 12 made of resin mold. The housing core 11 has a large-diameter cylindrical portion 11a, a disk portion 11b, and a small-diameter cylindrical portion 11c, and the large-diameter cylindrical portion 11a is press-fitted and fixed to the inner ring 2. Further, cut-and-raised portions 13 are provided in the outer circumferential direction at several locations around the edge of the small-diameter cylindrical portion 11c to prevent the sensor housing 12 from coming off. As can be seen from the cross-sectional shape, the outer peripheral edge of the sensor housing 12 reaches about the neutral line N of the outer ring 1, and has an L-shape in which the inner surface of the outer peripheral portion is cut out in the axial direction and the radial direction over the entire circumference. Is formed, and the magnetic encoder 8 is opposed to the step 14 with a predetermined gap.
[0020]
A part of the sensor housing 12 is provided with a concave part 15 which is long in the circumferential direction, and the magnetic sensor 17 supported by the electric circuit board 16 is accommodated in the concave part 15. The magnetic sensor 17 is exposed from the axial surface of the step portion 14 to the inner diameter surface, and faces the magnetic encoder 8 in a radial direction with a predetermined gap. Further, a cable extraction portion 18 is provided at the electric circuit board 16 so as to protrude in the inner diameter direction of the sensor housing 12. The cable take-out portion 18 is resin-molded with the cable 19 inserted therein. One end of the cable 19 is connected to the electric circuit board 16, and the other end is inserted through a protective tube 21 arranged inside the inner race 2 and pulled out.
[0021]
A normal seal member 22 is provided between the other ends of the outer ring 1 and the inner ring 2.
[0022]
FIG. 3 shows the products of the first embodiment, ie, “with welding” (however, welding is performed by laser welding) and the conventional product, that is, “without welding”, until the load is applied and the outer ring falls off due to repeated deformation. 5 is a test result of the number of deformation times. It was confirmed that "with welding" exhibited about 100 times the durability. Also, since laser welding has a very small thermal effect, there is no deformation before and after welding, and no demagnetization of the magnetic encoder occurs. Also, no cracks occur in the hardened steel bearing material. Further, welding can be performed in a state where the rust-preventive oil is applied. The same effect was observed in the case of electron beam welding.
[0023]
FIGS. 4A and 4B show another example of the core metal 7 of the magnetic encoder 8. In any case, the bending deformation of the outer race 1 is not propagated from the small-diameter cylindrical portion 7a to the welded portion 9 via the disk portion 7b or is difficult to propagate. In the case of FIG. 4A, the small-diameter cylindrical portion 7a of the cored bar 7 is fitted into the inner diameter surface of the outer ring 1 with a gap. In the case of FIG. 4B, the thickness t1 of the small-diameter cylindrical portion 7a is set to 0.5 to 0.8 times the thickness t of the other portions, that is, t1 = 0.5 to 0.8 × t. You have set.
[0024]
Next, in both the second embodiment shown in FIG. 5 and the third embodiment shown in FIG. 6, the structure of the bearing is the same as that of the first embodiment. This adopts the creep preventing structure of Patent Document 3 described above as the fitting structure. That is, in the case of the second embodiment shown in FIG. 5, two circumferential grooves 24, 24 are provided on the outer peripheral surface of the outer race 1 at a required interval, and ring-shaped annular bodies 25, 25 are provided in the respective circumferential grooves 24, 24. (For example, O-ring rubber), and these ring-shaped annular bodies 25 are pressed against the inner peripheral surface of the bearing box 23. A sealed space in which a viscous lubricant 26 such as grease is adhered is formed between the two ring-shaped annular bodies 25.
[0025]
In the case of the third embodiment shown in FIG. 6, the circumferential grooves 24, 24 are provided on the inner circumferential surface of the bearing housing 23, and the similar ring-shaped annular bodies 25, 25 mounted in the circumferential grooves 24, 24 are connected to the outer ring 1 Is pressed against the outer peripheral surface. The point that a sealed space in which a viscous lubricant 26 such as grease is adhered is formed between the two ring-shaped annular bodies 25, 25 as in the case of the second embodiment.
[0026]
In any of the above embodiments, when the load is applied to the outer ring 1 during use and the bearing ring 23 is eccentric in the direction of the load, the viscous lubricant 26 is interposed between the two ring-shaped rings 25, 25. To form a high-pressure fluid thin film, and the outer ring 1 is supported via the fluid thin film. The ring-shaped annular bodies 25, 25 prevent the viscous lubricant 26 from leaking, and prevent the outer ring 1 floating by the thin film from rotating in the rotational direction due to friction of the bearing, thereby preventing the occurrence of creep. You.
[0027]
Further, when the bearing is assembled, even if the shaft is tightly fitted to the inner ring 2, the fitting between the outer ring 1 and the bearing box 23 is a loose fit by the elasticity of the ring-shaped annular bodies 25, 25. Therefore, there is no problem in assembling the bearing, and the bearing can be assembled smoothly.
[0028]
【The invention's effect】
As described above, according to the present invention, in the outer ring rotating type bearing, the small-diameter cylindrical portion of the core metal of the magnetic encoder attached to the outer ring is press-fitted into the inner surface of the outer ring, and the disk portion of the core metal and the large-diameter disk portion are large. Since the core metal is fixed to the outer ring by welding the corner of the diameter cylindrical portion to the outer ring, it is possible to prevent the magnetic encoder from coming off from the outer ring.
[0029]
In addition, by performing the above-described welding by laser welding or electron beam welding, since there is little thermal influence, deformation and cracks of the outer ring do not occur, and demagnetization of the magnetic encoder can be prevented. Since welding can be performed in a state where rust-preventive oil is applied, the operation can be simplified.
[0030]
Further, by setting the welding position of the core metal to the outer ring on or near the center line of the compressive stress and the tensile stress of the bending of the outer ring, it is possible to prevent the repeated shearing force from acting on the welded portion.
[0031]
If a creep prevention structure is adopted in which at least two ring-shaped rings are interposed between the outer peripheral surface of the outer ring and the bearing box, and a viscous lubricant is adhered between the ring-shaped rings, the bearing of the outer ring may be used. Since the assembling to the box is facilitated, the inner ring and the shaft can be tightly fitted. As a result, relative rotation between the inner ring and the shaft is prevented, and disconnection of the cable can be prevented.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an embodiment; FIG. 2 is a front view of the same; FIG. 3 is a graph of experimental results of the same; FIG. 4 (a) and (b) are partial cross-sectional views of another example of the same; FIG. 6 is a partially enlarged sectional view of a second embodiment. FIG. 6 is a partially enlarged sectional view of a third embodiment.
DESCRIPTION OF SYMBOLS 1 Outer ring 2 Inner ring 3 Track 4 Track 5 Cage 6 Ball 7 Core metal 7a Small diameter cylindrical part 7b Disk part 7c Large diameter cylindrical part 8 Magnetic encoder 9 Welding part 11 Housing core metal 12 Sensor housing 13 Cut-and-raised piece 14 Step part 15 Recess Reference Signs List 16 Electric circuit board 17 Magnetic sensor 18 Cable take-out part 19 Cable 21 Protective tube 22 Seal member 23 Bearing box 24 Peripheral groove 25 Ring ring 26 Viscous lubricant

Claims (4)

An outer ring rotating type rotation sensor bearing in which an encoder is attached to an outer ring via a core bar, a sensor facing the encoder with a required clearance is attached to an inner ring, and the inner ring is used as a fixed side and the outer ring is used as a rotation side. 3. The bearing with a rotation sensor according to claim 1, wherein the core of the encoder is press-fitted into the outer ring, and the core is fixed to the outer ring by laser welding or electron beam welding. The bearing with a rotation sensor according to claim 1, wherein a welding position of the core metal to the outer ring is set on or near a center line of the compressive stress and the tensile stress of bending of the outer ring. The bearing with a rotation sensor according to claim 1, wherein the welding is performed on the entire circumference or at several points of the metal core. 4. The method according to claim 1, wherein at least two ring-shaped rings are interposed between the outer peripheral surface of the outer ring and the bearing housing, and a viscous lubricant is attached between the ring-shaped rings. A bearing with a rotation sensor according to any one of the above.

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