JP2004037133A - Rotation detector and bearing with rotation detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotation detector which can be build in a small apparatus and can deliver a highly accurate rotational angle. <P>SOLUTION: The rotation detector comprises a magnetism generating means 4 arranged on the rotary side member 1, a line sensor 5 arranged on a non-rotary side member 2 and detecting the magnetism of the magnetism generating means 4, and a means 6 for calculating the rotational angle of the magnetism generating means 4 from the output of the magnetic line sensor 5. The magnetism generating means 4 has circumferential anisotropy about the center of rotation O. The magnetic line sensor 5 and the angle calculating means 6 are integrated on one semiconductor chip 9. The magnetic line sensor 5 is arranged on each side of a rectangle. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a rotation detection device used for rotation detection in various devices, for example, rotation detection for controlling the rotation of a small motor and rotation detection for detecting the position of office equipment.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, there is a type in which a rotation sensor is incorporated in a rolling bearing, focusing on the advantage of being compact and easy to assemble. An example is shown in FIG. In the figure, a magnetic encoder 54 made of rubber is fixed to a rotating wheel 52 of a rolling bearing 51, and a magnetic sensor 55 such as a Hall element is arranged on a stationary wheel 53. By employing such a configuration, a rotation pulse signal and a rotation direction can be obtained.
[0003]
[Problems to be solved by the invention]
However, in the structure in which the magnetic encoder 54 is provided, in a small-diameter bearing in which the size of the rolling bearing 51 is small, it is difficult to accommodate the magnetic sensor 55 within the outer diameter of the stationary wheel 53, or the rotation in one rotation. There is a drawback that it is difficult to detect a rotation angle with high accuracy enough to secure 500 or more pulses.
[0004]
An object of the present invention is to provide a rotation detection device that can be incorporated into a small device and that can output a highly accurate rotation angle.
Another object of the present invention is to provide a bearing with a rotation detecting device capable of obtaining a highly accurate rotation angle output even if the bearing is downsized.
[0005]
[Means for Solving the Problems]
A rotation detecting device according to the present invention includes: a magnet generating means disposed on a rotating member and having a circumferential anisotropy around a rotation center; and a non-rotating member opposed to the magnet generating means in an axial direction of the rotation center. And a magnetic line sensor for detecting the magnetism of the magnetic generating means, and an angle calculating means for calculating the rotation angle of the magnetic generating means from the output of the magnetic line sensor.
When the rotating member rotates, a detection signal corresponding to the rotation angle is output from each magnetic sensor element of the magnetic line sensor due to the relative rotation between the magnetism generating means and the magnetic line sensor. The angle calculation means calculates the rotation angle from the output of the magnetic line sensor. That is, due to the rotation, the magnetic field pattern of the magnetism generating means detected by the arrangement of the magnetic sensor elements in the magnetic line sensor changes, and the angle is calculated based on the change. Since detection is performed by a plurality of magnetic sensor elements arranged in a line, even a slight difference in rotation angle can be detected. The magnetic sensor elements have small dimensions and can be arranged at high density. Therefore, high-resolution angle detection is possible even if the magnetism generating means is not a subdivided one such as a magnetic encoder. Since the magnetism generating means does not need to be subdivided, it is easy to secure the magnetic field strength required for detection even if the size is reduced. For these reasons, even if the size is reduced, a high-precision rotation angle output is possible, so that it can be incorporated into a small device. Further, since angle information can be obtained by a change in the magnetic field pattern, there is no need for axis alignment, and assembly is easy. Furthermore, the angle information is less susceptible to temperature fluctuations and power supply voltage fluctuations. In addition, the fact that the magnetic generating means has circumferential anisotropy around the center of rotation means that the rotating position of the generated magnetic field in the N magnetic pole range and the S magnetic pole range is It is a shape that changes. The entire outer shape of the magnetism generating means does not matter.
[0006]
The magnetism generating means may be made of a permanent magnet or a permanent magnet and a magnetic material. In this case, the magnetism generating means may have only a pair of magnetic poles. Further, the angle calculation means may detect the zero cross of the magnetic field distribution from the output of the magnetic line sensor and calculate the rotation angle. That is, the rotation angle is detected by detecting the zero position that changes between the north pole and the south pole.
If the magnetism generating means is made of a permanent magnet or a permanent magnet and a magnetic material as described above, the mechanical structure of the rotating member can be simple and robust. Further, by setting the angle calculating means to calculate the rotation angle from the zero crossing of the N pole and the S pole of the magnetic field distribution, the accuracy of the detected angular position can be improved.
[0007]
The magnetic line sensors may be arranged along each of the four sides of the virtual rectangle, and the number of magnetic line sensors on each side may be at least one or more. The number of magnetic line sensors on each side may be one, or a plurality of magnetic line sensors may be provided in parallel.
By arranging the magnetic line sensors in a rectangular shape, detection signals with phases shifted by 90 degrees can be obtained, and accurate angle detection can be performed by simple arithmetic processing.
[0008]
In such a rectangular arrangement, the angle calculating means may be arranged inside the rectangular arrangement of the magnetic line sensors arranged on each side. With this arrangement relationship, the inside of the rectangle in which the magnetic line sensor cannot be arranged can be effectively used as an arrangement place of the angle calculation means, and the magnetic line sensor and the angle calculation means can be arranged efficiently and compactly. Can be.
[0009]
The magnetic line sensor and the angle calculating means may be integrated on one semiconductor chip. The angle calculating means is an integrated circuit formed on this semiconductor chip.
In this way, when the magnetic line sensor and the angle calculating means are integrated on one semiconductor chip, wiring between the magnetic line sensor and the angle calculating means is not required, and the size can be further reduced, and the reliability against disconnection and the like can be improved. And the assembling work of the rotation detecting device is also facilitated. In particular, when the angle calculation means is arranged inside the arrangement of the plurality of magnetic line sensors, for example, inside the rectangular arrangement, the chip size can be made smaller.
[0010]
The angle calculating means includes an amplifier for amplifying the output of the magnetic line sensor, an A / D converter for digitizing the amplified analog output, a spatial filter for removing noise from the digital output, It may have a zero detection unit that detects a zero cross of the magnetic field distribution from the output of the filter unit, and an angle calculation unit that calculates the rotation angle from the output of the zero detection unit. With this configuration, the rotation angle output can be accurately obtained as a digital value.
[0011]
The angle calculating means may convert the calculation result of the rotation angle into a pulse and output a pulse. With this configuration, an incremental signal can be output as the rotation angle output.
[0012]
In the rotation detecting device having the above-mentioned configuration according to the present invention, a transmitter for wirelessly transmitting the angle information calculated by the angle calculating means may be provided adjacent to the magnetic line sensor. The wireless transmitter may use a radio wave, or may use an optical signal or another signal capable of transmitting electric space.
If a wireless transmitter is used, signals can be extracted without an output cable. Further, by providing this transmitter adjacent to the magnetic line sensor, a compact rotation detecting device with a transmitter is provided.
[0013]
A bearing with a rotation detecting device according to the present invention is one in which the rotation detecting device having any one of the above-described structures according to the present invention is incorporated in a rolling bearing. In that case, the magnetism generating means is arranged on the rotating raceway which is the rotating member. The magnetic line sensor is disposed on the stationary raceway, which is a non-rotating member.
As described above, by integrating the rotation detecting device with the rolling bearing, the number of parts and the number of assembling steps of the equipment using the bearing can be reduced, and the size can be reduced. In this case, since the rotation detecting device can output a rotation angle with high accuracy and small size as described above, a satisfactory rotation angle output can be obtained even with a small bearing such as a small-diameter bearing.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows the principle configuration of the rotation detecting device of this embodiment. The rotating member 1 and the non-rotating member 2 are members on the rotating and non-rotating sides that rotate relatively. The rotation detecting device 3 includes a magnetic generating unit 4 disposed on the rotating member 1, a magnetic line sensor 5 disposed on the non-rotating member 2, and a rotation of the magnetic generating unit 4 based on an output of the magnetic line sensor 5. And an angle calculating means 6 for calculating an angle. The magnetic line sensor 5 is arranged with a slight gap from the magnetism generating means 4.
[0015]
The magnetism generating means 4 is such that the magnetism generated has a circumferential anisotropy around the rotation center O of the rotating member 1 and is made of a single permanent magnet or a composite of a permanent magnet and a magnetic material. Here, the magnetism generating means 4 is formed by integrating one permanent magnet 7 by sandwiching it between two magnetic yokes 8, 8, and has a generally forked bifurcated shape. One end of the yoke 8 is an N magnetic pole, and one end of the other magnetic yoke 8 is an S magnetic pole. With such a structure of the magnetism generating means 4, a simple and robust structure can be achieved. The magnetic generating means 4 is attached to the rotating member 1 such that the rotation center O of the rotating member 1 coincides with the center of the magnetic generating means 4. The magnetic pole and the S magnetic pole pivot.
[0016]
The magnetic line sensor 5 is a sensor for detecting the magnetism of the magnetism generating means 4 and is arranged on the non-rotational side member 2 so as to face the magnetism generation means 4 in the axial direction of the rotation center O of the rotation side member 1. Is done. Here, the magnetic line sensors 5 are arranged along the four sides of the virtual rectangle as shown in FIG. 2, and the number of magnetic sensor elements 5a in the sensor rows 5A to 5D on each side is at least one or more. Have been. In this case, the center of the rectangle coincides with the rotation center O of the rotating member 1. In order to increase the detection accuracy of the magnetic line sensor 5, the number of the sensor rows 5A to 5D is preferably as large as possible. For example, as shown in FIG. 3, a plurality of magnetic line sensors 5 are arranged in parallel along each side of a rectangle. It is also possible to configure it. The magnetic line sensor 5 configured as described above is formed on a surface of one semiconductor chip 9 attached to the non-rotating side member 2 and facing the magnetic generation means 4. The semiconductor chip 9 is, for example, a silicon chip.
[0017]
The angle calculation means 6 is formed of an integrated circuit, and is integrated on the semiconductor chip 9 together with the magnetic line sensor 5. The angle calculation means 6 is arranged inside the rectangular arrangement of the magnetic line sensor 5. Thereby, the magnetic line sensor 5 and the angle calculating means 6 can be arranged compactly.
FIG. 4 is a conceptual configuration example in which the angle calculation means 6 obtains an absolute output. The angle calculating means 6 includes an amplifier 11 for amplifying the output of the magnetic line sensor 5, an A / D converter 12 for digitizing the amplified analog output, and a spatial filter for removing noise from the digital output. 13, a zero detector 14 for detecting a zero crossing of the magnetic field distribution from the output of the spatial filter 13, and an angle calculator 15 for calculating the rotation angle of the magnetism generating means 4 from the output of the zero detector 14.
[0018]
FIG. 5 is a waveform diagram illustrating the noise removal function of the spatial filter unit 13. FIG. 5A shows an output waveform of the magnetic line sensor 5. In the figure, the horizontal axis indicates the arrangement position of each magnetic sensor element 5a in the sensor rows 5A to 5D, and the vertical axis indicates the magnetic field strength (for example, the north pole is above the horizontal axis and the south pole is below). As can be seen from the waveform of FIG. 5A, the output of the magnetic line sensor 5 is a digital output having a variation. FIG. 5B is a spectrum display of this output in the frequency domain, where the horizontal axis indicates frequency and the vertical axis indicates intensity. As can be seen from the figure, the characteristic variation of the magnetic line sensor 5 is superimposed on the original signal component P as a noise Q extending to a high frequency as indicated by oblique lines. The spatial filter unit 13 reduces the noise Q as shown in FIG. 5D by applying a digital filter F to the output of the magnetic line sensor 5 as shown in FIG. 5C. As a result, the sensor output that has passed through the spatial filter unit 13 has a waveform with reduced noise due to sensor variations as shown in FIG. As the spatial filter 13 having such a function, for example, a comb filter can be used.
[0019]
6 and 7 are explanatory diagrams of the angle calculation processing by the angle calculation unit 15. FIGS. 6A to 6D show output waveform diagrams of the magnetic line sensors 5 by the respective sensor arrays 5A to 5D when the rotating member 1 is rotating, and the horizontal axis thereof indicates the respective sensor arrays 5A to 5D. 5D shows the arrangement position of the magnetic sensor elements 5a, and the vertical axis shows the strength of the detected magnetic field.
Now, it is assumed that there is a zero cross position at a position X1 and X2 shown in FIG. 7 which is a boundary between the N magnetic pole and the S magnetic pole of the magnetic field detected by the magnetic line sensor 5. In this state, the outputs of the sensor arrays 5A to 5D of the magnetic line sensor 5 have the signal waveforms shown in FIGS. Therefore, the zero cross positions X1 and X2 can be calculated by linear approximation from the outputs of the sensor arrays 5A and 5C.
The angle calculation can be performed by the following equation (1).
θ = tan ⁻¹ (2 L / b) (1)
Here, θ is a value indicating the rotation angle θ of the magnetism generating means 4 as an absolute angle (absolute value). 2L is the length of one side of each magnetic line sensor 5 arranged in a rectangle. b is the horizontal length between the zero cross positions X1 and X2.
When the zero cross positions X1 and X2 are located in the sensor rows 5B and 5D, the rotation angle θ is calculated in the same manner as described above, based on the zero cross position data obtained from the outputs.
As described above, since the rotation angle is calculated from the zero cross of the magnetic field distribution, the detection accuracy can be improved. In addition, since the angle information is obtained from the magnetic field pattern, the alignment of the rotation detecting device 3 is not required, and the mounting becomes easy.
[0020]
FIG. 8 shows an example in which the rotation detecting device 3 of this embodiment is incorporated in a rolling bearing. The rolling bearing 20 has a rolling element 24 held by a retainer 23 interposed between rolling surfaces of an inner ring 21 and an outer ring 22. The rolling element 24 is formed of a ball, and the rolling bearing 20 is a deep groove ball bearing. Further, a seal 25 covering one end of the bearing space is attached to the outer ring 22.
The inner race 21 to which the rotating shaft 10 fits is supported by the outer race 23 via a rolling element 24. The outer ring 23 is installed in a housing (not shown) of the equipment using the bearing.
[0021]
A magnet generating means attaching member 26 is attached to the inner ring 21, and the magnet generating means 4 is attached to the magnet generating means attaching member 26. The magnet generating means mounting member 26 is provided so as to cover the inner diameter hole at one end of the inner ring 21, and the cylindrical portion 26 a provided on the outer peripheral edge is fitted to the outer peripheral surface of the shoulder of the inner ring 21, so that Installed. Further, the side plate near the cylindrical portion 26a is engaged with the width surface of the inner race 21 to perform axial positioning.
A sensor mounting member 27 is mounted on the outer race 22, and the semiconductor chip 9 in which the magnetic line sensor 5 and the angle calculating means 6 of FIG. 1 are integrated is mounted on the sensor mounting member 27. An output cable 29 for extracting the output of the angle calculation means 6 is also attached to the sensor attachment member 27. The sensor mounting member 27 fits the distal end cylindrical portion 27a of the outer peripheral portion to the inner diameter surface of the outer ring 22 and engages the flange portion 27b formed in the vicinity of the distal end cylindrical portion 27a with the width surface of the outer ring 22 so that the axial direction is Positioning has been done.
[0022]
In such a configuration, if the detection size of each magnetic sensor element 5a constituting the magnetic line sensor 5 is, for example, 10 μm square and the number of elements of each sensor row 5A to 5D is 200, the length of each sensor row 5A to 5D is long. The height of the magnetic line sensor 5 is about 2 mm square. This size can be said to be a sufficiently small magnetic line sensor 5 in consideration of the fact that the outer diameter of a typical small-diameter bearing (model number # 608) is φ22 mm.
Although the details are omitted, it is considered that the rotation detecting device 3 having an angular resolution of 0.3 ° can be realized by using the magnetic line sensor 5 having about 200 elements in one sensor row. A remarkable improvement in performance can be expected from the resolution of 3 °.
Furthermore, if a wireless transmitter 31 or a receiver (not shown) for wireless radio waves or the like is provided adjacent to the semiconductor chip 9 as shown by a chain line in FIG. 1, detection can be performed without using the output cable 29 described above. The signal can be extracted.
[0023]
FIG. 9 is a block diagram showing another configuration example of the angle calculation means 6 in the rotation detection device 3. The angle calculating means 6A is provided with a pulse conversion section 16 at a stage subsequent to the angle calculating section 15 in the angle calculating means 6 in FIG. 4, and based on the angle information obtained by the angle calculating section 15, generates a detection signal as an incremental pulse signal. Is output. Specifically, as shown in FIG. 10, the rotation angle (360 °) for one rotation is previously set to a “0” section (black section in FIG. 10) and a “1” section (white section in FIG. 10) at predetermined angles. ) Is written in a storage means such as a ROM. The rotation angle θ obtained by the angle calculation unit 15 is compared with the data in the storage means, and “0” is set when the calculated rotation angle θ corresponds to the black portion in FIG. By outputting "1", an incremental pulse output is obtained from the angle calculation means 6A with the rotation of the magnetism generation means 4.
[0024]
【The invention's effect】
The rotation detecting device according to the present invention can realize a compact and high-precision rotation detecting device by a combination of the magnetism generating means and the magnetic line sensor. In particular, by using a magnetic sensor as a line sensor, high accuracy can be obtained with a small number of sensors. For these reasons, it can be incorporated into a small device.
If the angle calculation means calculates the angle by detecting the zero cross of the magnetic field distribution from the output of the magnetic line sensor, an improvement in the accuracy of the detected angular position can be expected. Further, when the magnetic line sensor is arranged in a rectangular shape and the angle calculating means is arranged therein, each component can be arranged with good space efficiency, resulting in a more compact configuration. When the magnetic line sensor and the angle calculating means are integrated on one semiconductor chip, further compactness is possible, reliability against disconnection and the like is improved, and the assembling work of the rotation detecting device is facilitated. .
Since the bearing with the rotation detecting device according to the present invention incorporates the rotation detecting device according to the present invention, a highly accurate rotation angle output can be obtained even when the bearing is downsized.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a conceptual configuration of a rotation detecting device according to an embodiment of the present invention.
FIG. 2 is a plan view showing an example of the arrangement of a magnetic line sensor and an angle calculation unit on a semiconductor chip in the rotation detection device.
FIG. 3 is a plan view showing another configuration example of the magnetic line sensor in the rotation detection device.
FIG. 4 is a block diagram showing an angle calculating means in the rotation detecting device.
FIG. 5 is an explanatory diagram of a function of a spatial filter unit in the angle calculating unit.
FIG. 6 is a waveform chart showing an output of a magnetic line sensor.
FIG. 7 is an explanatory diagram of an angle calculating process by an angle calculating unit.
FIG. 8 is a sectional view showing an example of a rolling bearing provided with the rotation detecting device.
FIG. 9 is a block diagram showing another configuration example of the angle calculation means.
FIG. 10 is an explanatory diagram for describing processing of a pulse conversion unit in the angle calculation unit.
FIG. 11 is a sectional view of a conventional example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Rotating side member 2 ... Non-rotating side member 3 ... Rotation detecting device 4 ... Magnetic generation means 5 ... Magnetic line sensors 5A-5D ... Sensor row 6 ... Angle calculation means 7 ... Permanent magnet 8 ... Magnetic body yoke 9 ... Semiconductor chip DESCRIPTION OF SYMBOLS 11 ... Amplification part 12 ... A / D conversion part 13 ... Spatial filter part 14 ... Zero detection part 15 ... Angle calculation part 16 ... Pulse conversion part 20 ... Rolling bearing O ... Rotation center

Claims (9)

A magnet generating means arranged on the rotating member and having circumferential anisotropy around the center of rotation; and a magnet generating means arranged on the non-rotating member opposite to the magnet in the axial direction of the center of rotation. A rotation detecting device comprising: a magnetic line sensor for detecting the magnetism of the magnetic field sensor; 2. The magnetic field generating means having a circumferential anisotropy according to claim 1, wherein the magnetic generating means comprises a permanent magnet or a permanent magnet and a magnetic material, and the angle calculating means detects a zero cross of a magnetic field distribution from an output of the magnetic line sensor. And a rotation detection device for calculating the rotation angle. 3. The rotation detecting device according to claim 1, wherein the magnetic line sensors are arranged along each of four sides of the virtual rectangle, and the number of magnetic line sensors on each side is at least one. 4. The rotation detecting device according to claim 3, wherein the angle calculating means is arranged inside a rectangular arrangement of magnetic line sensors arranged on each side. 5. A rotation detecting device according to claim 1, wherein the magnetic line sensor and the angle calculating means are integrated on one semiconductor chip. The angle calculating means according to any one of claims 1 to 5, wherein the angle calculating means amplifies an output of the magnetic line sensor, an A / D converter which digitizes the amplified analog output, and a digital output. A spatial filter that removes noise from the spatial filter, a zero detector that detects a zero crossing of the magnetic field distribution from the output of the spatial filter, and an angle calculator that calculates a rotation angle from the output of the zero detector. Rotation detection device. 7. The rotation detecting device according to claim 1, wherein the angle calculation unit converts the calculation result of the rotation angle into a pulse and outputs a pulse. 8. The rotation detecting device according to claim 1, wherein a transmitter for wirelessly transmitting the angle information calculated by the angle calculating means is provided adjacent to the magnetic line sensor. A bearing with a rotation detecting device incorporating the rotation detecting device according to claim 1.

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