JP2008064633A - Bearing device with sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bearing device with a sensor which is resistant to an external magnetic flux, capable of outputting a high-resolution rotation state signal. <P>SOLUTION: This device includes a bearing 12 wherein balls 20 are arranged between an inner ring 16 and an outer ring 18; a rotating member 22 supported by the inner ring 16 as a rotating ring, or formed integrally therewith; a cylindrical member 26 supported by the outer ring 18 as a static ring, for enclosing the outer circumferential surface of the rotating member 22; a pair of detection coils 28, 30 arranged on the cylindrical member 26; and a rotation state detector for detecting the rotation state of the rotating member 22 following outputs from each detection coil 28, 30. The rotating member 22 is constituted of a magnetic material, and a plurality of grooves 24 elongating in the axial direction are formed on the rotating member 22, and a plurality of windows 32, 34 are formed on the cylindrical member 26 so that the overlapping degree with the grooves 24 is changed corresponding to a relative rotation position of the rotating member 22, and windows 32, 34 in each row are enclosed by each detection coil 28, 30, and two-phase signals showing the rotation state of the rotating member 22 are output from the detection coils 28, 30. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a sensor-equipped bearing device, and more particularly, to a sensor-equipped bearing device that can be incorporated into a rotation support portion such as a robot arm or an automobile hub to detect an angle, a rotation angular velocity, and the like.

2. Description of the Related Art Conventionally, sensors that detect the angle of a rotating shaft and the rotational angular velocity are known. Among these sensors, a sensor-equipped bearing device in which a sensor having a rotation state detection function is added to a bearing has been proposed. For example, as disclosed in Patent Document 1, a magnetic pole of a magnet magnetized in multiple poles is detected by a Hall IC to detect a rotation state.
Patent Sho 63-111416

  However, the conventional sensor-equipped bearing device described above has a limit in reducing the pitch of the N / S poles of the encoder in order to increase the resolution. Further, the method of detecting the rotation state with a magnet has a problem that it is easily influenced by external magnetic flux.

  Accordingly, the present invention has been made in view of the above-described problems of the prior art, and an object thereof is to provide a sensor-equipped bearing device that is strong against external magnetic flux and can output a high-resolution rotation state signal.

  In order to achieve the above object, the present invention provides a bearing in which a plurality of rolling elements are disposed between a stationary wheel and a rotating wheel, a rotating member that is supported or integrally formed with the rotating wheel, and the stationary wheel. Rotating state detection for detecting a rotating state of the rotating member according to outputs of the pair of detection coils and a pair of detection coils arranged on the cylindrical member, a cylindrical member supported on the outer periphery of the rotating member The rotating member is made of a magnetic material, the rotating member has a plurality of grooves extending in the axial direction, and the cylindrical member has the groove according to a relative rotational position with respect to the rotating member. A sensor-equipped bearing device, wherein a plurality of windows are formed so that the degree of overlap with each other changes, and each of the detection coils is arranged so as to surround a region where the windows of the respective rows are formed. It is composed.

  According to the present invention, a rotating member made of a magnetic material is disposed inside the cylindrical member, and a plurality of grooves are formed in the rotating member in synchronization with the window of the cylindrical member, and are placed in a magnetic field. When the rotating member is magnetized by the magnetic material to generate magnetic flux, the amount increases according to the strength of the magnetic field until saturation. For this reason, the magnetic flux of the rotating member is increased or decreased by the relative phase with the cylindrical member by a magnetic field having a periodic strength in the circumferential direction and a gradient in the radial direction formed by the cylindrical member. The phase at which the magnetic flux is maximum is a state in which the center of the window and the center of the convex portion between the grooves coincide with each other. The change is almost sinusoidal. In addition, since the windows are formed to have a phase difference from each other, a two-phase signal having a phase difference is output from each detection coil as the rotation state of the rotating member. Can be increased by calculating with a rotation state detector. In addition, since the structure does not use a magnetic encoder, the rotational state of the rotating member can be detected with high accuracy against external magnetic flux.

  According to the present invention, it is strong against external magnetic flux and high resolution can be achieved, and the rotation state of the rotating member can be detected with high accuracy.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of a sensor-equipped bearing device according to an embodiment of the present invention, and FIG. 2 is an exploded perspective view of the sensor-equipped bearing device according to an embodiment of the present invention. 1 and 2, the sensor-equipped bearing device 10 includes a bearing 12, and a sensor 14 for detecting the rotation state of the bearing 12 is added to the bearing 12. The bearing 12 includes a plurality of balls 20 as rolling elements mounted between the inner ring 16, the outer ring 18, and the inner ring 16 and the outer ring 18, and one of the inner ring 16 and the outer ring 18 is stationary. The bearing device is configured as a ring and the other as a rotating wheel. When the inner ring 16 is a rotating ring, the inner ring 16 supports a rotating member 22 formed in a substantially cylindrical shape. The rotating member 22 is configured using a magnetic material as a magnetic body, and a plurality of concave and convex portions are formed at equal intervals along the circumferential direction on the outer peripheral side thereof. Of each uneven portion, the concave portion is formed as a groove 24, and the convex portion is formed between the groove 24 and the groove 24. That is, a plurality of grooves 24 extending in the axial direction are formed on the outer peripheral side of the rotating member 22, and the grooves 24 of each line are formed at equal intervals in the circumferential direction of the rotating member 22. A cylindrical member 26 is disposed outside the rotating member 22, and a pair of detection coils 28 and 30 are disposed on the outer peripheral side of the cylindrical member 26. The cylindrical member 26 and the detection coils 28 and 30 are supported by the outer ring 18 as a stationary ring.

  The cylindrical member 26 is formed of a conductive and non-magnetic material, and the cylindrical member 26 includes a plurality of rows of rectangular windows 32 and 34 spaced at equal intervals along the circumferential direction. Are formed so as to be shifted from each other by 90 degrees. The detection coils 28 and 30 are arranged so as to surround the windows 32 and 34 in each row, respectively. Each detection coil 28, 30 is connected to a rotation state detector (not shown), and a sinusoidal voltage is applied to each detection coil 28, 30 from the rotation state detector. . The rotation state detector applies a sinusoidal voltage to each of the detection coils 28 and 30 to induce an electromotive force in each of the detection coils 28 and 30, and based on this electromotive force, the rotation state of the rotary member 22 is set to the angle. Is calculated.

  In the above configuration, when the inner ring 16 rotates as a rotating wheel, the rotating member 22 rotates accordingly. At this time, when the cylindrical member 26 does not have the windows 32 and 34, the cylindrical member 26 is made of a conductive and nonmagnetic material. Therefore, an alternating current is passed through the detection coils 28 and 30 to detect the detection coil 28. When an alternating magnetic field is generated inside 30, an eddy current is generated on the outer peripheral surface of the cylindrical member 26 in a direction opposite to the coil current flowing through the detection coils 28 and 30. When the magnetic field generated by the eddy current and the magnetic field generated by the detection coils 28 and 30 are overlapped, the magnetic field inside the cylindrical member 26 is canceled.

  On the other hand, when the windows 32 and 34 are provided in the cylindrical member 26 in two rows, the eddy current generated on the outer peripheral surface of the cylindrical member 26 cannot go around the outer peripheral surface by the windows 32 and 34. 34 wraps around the inner peripheral surface side of the cylindrical member 26 along the end surface of 34, flows in the same direction as the coil current on the inner peripheral surface, and returns to the outer peripheral surface side along the end surface of the adjacent window 32 or window 34. Form a loop. In other words, eddy current loops are periodically arranged in the circumferential direction inside the detection coils 28 and 30.

  A rotating member 22 made of a magnetic material is coaxially arranged inside the cylindrical member 26, and grooves 24 are formed in the rotating member 22 along the axial direction at the same period as the windows 32 and 34. The rotating member 22 placed in the magnetic field is magnetized to generate a magnetic flux, but the amount increases according to the strength of the magnetic field before saturation.

  For this reason, the magnetic flux of the rotating member 22 increases / decreases depending on the relative phase with the cylindrical member 26 by a magnetic field having a periodic strength in the circumferential direction and a gradient in the radial direction created by the cylindrical member 26. At this time, the phase at which the magnetic flux becomes maximum is a state in which the center of each of the windows 32 and 34 and the center of the convex portion between the groove 24 and the groove 24 coincide with each other. The inductances 28 and 30 also increase or decrease. The change is almost sinusoidal. At this time, since the windows 32 and 34 are formed so as to have a phase of 90 degrees, the detection coils 28 and 30 have a phase difference of 90 degrees as a signal indicating the rotation state of the rotating member 22. A two-phase signal is output. The rotation state detector can calculate the angle, rotation speed, rotation direction, and the like of the rotation member 22 as the rotation state of the rotation member 22 based on the input two-phase signal, and the angle, rotation speed, rotation direction, etc. The calculation result is output as an analog signal, a digital signal, or a pulse signal. In this case, if the rotation state detector generates a pulse by dividing one period in particular, it is possible to generate a pulse of “number of pulses of one period × number of periods”, and high resolution can be achieved.

The rotation state detector may be incorporated in the bearing or may be externally attached.
Further, in the above embodiment, an example of application to a ball bearing has been shown, but the present invention is not limited to this. May be.

  Moreover, in the said actual form, although the rotation member 22 is made into the structure supported by the inner ring | wheel 16, when the rotation member 22 and the inner ring | wheel 16 are formed integrally, since a number of parts can be reduced, it is preferable. Moreover, in the said embodiment, although the phase difference of the windows 32 and 34 is formed at 90 degree | times, it is not limited to this. However, if the phase difference is 90 degrees, the phase difference between the two-phase signals is 90 degrees, and the angle can be easily calculated. Therefore, a phase difference of 90 degrees is preferable.

  According to the present embodiment, unlike the magnetic encoder system, it is strong against external magnetic flux, can have high resolution, and can detect the rotation state of the rotating member 22 with high accuracy.

It is a perspective view of the bearing apparatus with a sensor which shows one Example of this invention. It is a disassembled perspective view of the bearing apparatus with a sensor which shows one Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Bearing apparatus with a sensor 12 Bearing 14 Sensor 16 Inner ring 18 Outer ring 20 Ball 22 Rotating member 24 Groove 26 Cylindrical member 28, 30 Detection coil 32, 34 Window

Claims (5)

  A bearing in which a plurality of rolling elements are disposed between a stationary wheel and a rotating wheel, a rotating member that is supported by or integrally formed with the rotating wheel, and an outer peripheral surface of the rotating member that is supported by the stationary wheel. A surrounding cylindrical member; a pair of detection coils disposed on the cylindrical member; and a rotation state detector that detects a rotation state of the rotation member in accordance with outputs of the pair of detection coils. The rotating member is formed with a plurality of axially extending grooves, and the cylindrical member has a window so that the overlapping state with the groove changes according to the relative rotational position of the rotating member. A sensor-equipped bearing device, wherein the detection coils are arranged so as to surround a region where a plurality of rows are formed and the windows of the rows are formed.   The sensor-equipped bearing device according to claim 1, wherein the rotation state detector detects a rotation state of the rotating member from a ratio of outputs of the detection coils.   3. The sensor-equipped bearing device according to claim 1, wherein the rotation state detector outputs the rotation state of the rotating member as an analog signal.   3. The sensor-equipped bearing device according to claim 1, wherein the rotation state detector outputs a rotation state of the rotation member as a digital signal.   The sensor-equipped bearing device according to claim 1, wherein the rotation state detector outputs a rotation state of the rotating member by a pulse signal.

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