JP3973983B2 - Rotation detection device and bearing with rotation detection device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a rotation detection device used for rotation detection in various devices, for example, rotation detection for rotation control of a small motor and rotation detection for position detection of office equipment.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, there is a type in which a rotation sensor is built 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 rubber magnetic encoder 54 is fixed to a rotating wheel 52 of a rolling bearing 51, and a magnetic sensor 55 such as a Hall element is disposed on a stationary wheel 53. By adopting 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 provided with the magnetic encoder 54 described above, in a small-diameter bearing with a small size of the rolling bearing 51, it is difficult to accommodate the magnetic sensor 55 within the outer diameter of the stationary ring 53, or the rotation with one rotation. There is a drawback that it is difficult to detect a rotation angle with a high degree of accuracy that can 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 can output a highly accurate rotation angle.
Another object of the present invention is to provide a bearing with a rotation detection device that can obtain a highly accurate rotation angle output even if it is downsized.
[0005]
[Means for Solving the Problems]
A rotation detection device according to the present invention includes a magnetism generating means disposed on a rotation side member and having circumferential anisotropy around a rotation center, and a non-rotation side member facing the magnetism generation means in the 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 rotation-side member rotates, a detection signal corresponding to the rotation angle is output from each magnetic sensor element in the magnetic line sensor due to 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, the rotation changes the magnetic field pattern of the magnetism generating means detected by the arrangement of the magnetic sensor elements in the magnetic line sensor, 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. Magnetic sensor elements have small dimensions and can be arranged with high density. For this reason, angle detection with high resolution is possible even if the magnetism generating means is not subdivided like a magnetic encoder. Since the magnetism generating means does not need to be subdivided, it is easy to ensure the magnetic field strength necessary for detection even if the size is reduced. For these reasons, even if a reduction in size is achieved, a highly accurate rotation angle output is possible, so that it can be incorporated into a small device. In addition, since the angle information can be acquired by changing the magnetic field pattern, alignment is not necessary, and assembly is easy. Furthermore, the angle information is not easily affected by temperature fluctuations and power supply voltage fluctuations. Note that the magnetism generating means has circumferential anisotropy around the rotation center means that the rotation positions of the N magnetic pole range and the S magnetic pole range of the generated magnetic field are determined by the magnetism generating means rotating around the rotation center. Say that the shape changes. The overall external shape of the magnetic generation means is not limited.
[0006]
The magnetism generating means is composed 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, and performs the calculation of the rotation angle by detecting a zero crossing of the magnetic field distribution from the output of the magnetic line sensor. That is, from the outputs of a plurality of magnetic sensor elements constituting the magnetic line sensor, a zero cross position which is a position where the magnetic field distribution on the magnetic line sensor changes as a boundary between the N pole and the S pole is obtained. The rotation angle is calculated from the above. The angle calculation means may calculate the zero cross position by linear approximation from the outputs of the plurality of magnetic sensor elements of the magnetic line sensor.
When the magnetism generating means is made of a permanent magnet or a permanent magnet and a magnetic material in this way, the mechanical structure of the rotating member can be configured simply and robustly. The angle calculation means, by which shall be calculated zero-cross position or et rotational angle of N pole and S pole of the magnetic field distribution, it is possible to improve the accuracy of the angular position detected.
[0007]
The magnetic line sensor may be disposed along each side of four sides of a virtual rectangle, and the number of magnetic line sensors on each side may be at least one. There may be one magnetic line sensor on each side, or a plurality of magnetic line sensors may be provided in parallel.
When the magnetic line sensors are arranged in a rectangular shape, detection signals with phases shifted by 90 degrees can be obtained, and accurate angle detection can be performed with simple arithmetic processing.
[0008]
When the rectangular arrangement is used as described above, the angle calculating means may be arranged inside the rectangular arrangement of the magnetic line sensors arranged on each side. By adopting this arrangement relationship, the inside of the rectangle where the magnetic line sensor cannot be arranged can be effectively used as the arrangement position of the angle calculating means, and the planar arrangement of the magnetic line sensor and the angle calculating means can be efficiently arranged in a compact manner. Can do.
[0009]
The magnetic line sensor and the angle calculation means may be integrated on one semiconductor chip. The angle calculation means is an integrated circuit formed on this semiconductor chip. As described above, when the magnetic line sensor and the angle calculating means are integrated on one semiconductor chip, the wiring between the magnetic line sensor and the angle calculating means is not required, and further downsizing is possible and reliability against disconnection and the like. As a result, the assembly operation of the rotation detecting device is facilitated. In particular, when the angle calculation means is arranged inside the arrangement of a plurality of magnetic line sensors, for example, inside the rectangular arrangement, the chip size can be further reduced.
[0010]
The angle calculation means includes an amplification unit that amplifies the output of the magnetic line sensor, an A / D conversion unit that digitizes the amplified analog output, a spatial filter unit that removes noise from the digital output, a zero detection section from the output of the filter unit to detect a zero-cross position of the magnetic field distribution may be as having a angle calculation unit that calculates a rotation angle from the output of the zero detector. With this configuration, the rotation angle output can be obtained with a digital value with high accuracy.
[0011]
The angle calculation means may convert the rotation angle calculation result into a pulse and output the pulse. With this configuration, an incremental signal can be output as the rotation angle output.
[0012]
In the rotation detection device having the above-described configurations according to the present invention, a transmitter that wirelessly transmits angle information calculated by the angle calculation means may be provided adjacent to the magnetic line sensor. Even if the wireless transmitter uses radio waves, it may use an optical signal or a signal capable of transmitting other space.
If a wireless transmitter is used, a signal can be extracted without an output cable. Further, by providing this transmitter adjacent to the magnetic line sensor, a compact rotation detection device with a transmitter is obtained.
[0013]
The bearing with a rotation detection device of the present invention is a rolling bearing in which the rotation detection device having any one of the above configurations according to the present invention is incorporated. In this case, the magnetism generating means is disposed on the rotation side race that is the rotation side member. The magnetic line sensor is arranged on a stationary side race that is a non-rotating side member.
In this way, by integrating the rotation detection device with the rolling bearing, the number of parts of the bearing-using device, the number of assembly steps can be reduced, and the size can be reduced. In that case, since the rotation detection device can output a rotation angle with a small size and high accuracy as described above, a satisfactory rotation angle output can be obtained even with a small bearing such as a small-diameter bearing.
[0014]
DETAILED DESCRIPTION OF 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 detection device of this embodiment. The rotation side member 1 and the non-rotation side member 2 are the rotation side and non-rotation side members which rotate relatively. The rotation detection device 3 includes a magnetism generating means 4 disposed on the rotation side member 1, a magnetic line sensor 5 disposed on the non-rotation side member 2, and rotation of the magnetism generation means 4 from the output of the magnetic line sensor 5. Angle calculating means 6 for calculating an angle. The magnetic line sensor 5 is arranged with a slight gap with respect to the magnetism generating means 4.
[0015]
The magnetism generating means 4 is one in which the generated magnetism has circumferential anisotropy around the rotation center O of the rotating side member 1 and is composed of a single permanent magnet or a composite of a permanent magnet and a magnetic material. Here, the magnetism generating means 4 is integrated with one permanent magnet 7 sandwiched between two magnetic yokes 8 and 8, and is roughly bifurcated fork-shaped. 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. By adopting such a structure for the magnetism generating means 4, a simple and robust construction can be achieved. The magnetism generating means 4 is attached to the rotation side member 1 so that the rotation center O of the rotation side member 1 coincides with the center of the magnetism generation means 4, and the rotation side member 1 rotates N around the rotation center O. The magnetic pole and the S magnetic pole pivot.
[0016]
The magnetic line sensor 5 is a sensor that detects the magnetism of the magnetism generating means 4 and is arranged on the non-rotating side member 2 so as to face the magnetism generating means 4 in the axial direction of the rotation center O of the rotating side member 1. Is done. Here, the magnetic line sensor 5 is arranged along each side of four sides of a 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. Has been. In this case, the center of the rectangle coincides with the rotation center O of the rotation side member 1. In order to increase the detection accuracy of the magnetic line sensor 5, it is better that the number of sensor rows 5A to 5D is larger. For example, as shown in FIG. 3, a plurality of magnetic line sensors 5 are arranged in parallel along each side of a rectangle. May be configured. The magnetic line sensor 5 configured as described above is formed on the surface of the one semiconductor chip 9 attached to the non-rotating side member 2 so as to face the magnetism generating means 4. The semiconductor chip 9 is a silicon chip, for example.
[0017]
The angle calculation means 6 comprises an integrated circuit and is integrated with the magnetic line sensor 5 on the semiconductor chip 9. 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 calculation means 6 can be arrange | positioned compactly.
FIG. 4 is a conceptual configuration example in which the angle calculation means 6 obtains an absolute output. The angle calculation means 6 includes an amplification unit 11 that amplifies the output of the magnetic line sensor 5, an A / D conversion unit 12 that digitizes the amplified analog output, and a spatial filter unit that removes noise from the digital output. 13, a zero detection unit 14 which detects the zero-cross position of the magnetic field distribution from the output of the spatial filter section 13, and an angle calculator 15 for calculating a rotation angle of the magnetic generating element 4 from the output of the zero detector 14 Have.
[0018]
FIG. 5 is a waveform diagram illustrating the noise removal function of the spatial filter unit 13. 5A shows an output waveform of the magnetic line sensor 5. In the figure, the horizontal axis indicates the position of the magnetic sensor elements 5a in the sensor rows 5A to 5D, and the vertical axis indicates the magnetic field intensity (for example, N pole above the horizontal axis and S pole below). As can be seen from the waveform in FIG. 5A, the output of the magnetic line sensor 5 is a digital output with variations. FIG. 5B is a spectrum display of this output in the frequency domain, where the horizontal axis represents frequency and the vertical axis represents 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 noise Q extending to a high frequency as shown by the oblique lines. The spatial filter unit 13 reduces the noise Q as shown in FIG. 5 (D) by applying a digital filter F to the output of the magnetic line sensor 5 as shown in FIG. 5 (C). Thereby, the sensor output which passed through the spatial filter part 13 becomes a waveform in which noise due to sensor variation is reduced 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 angle calculation processing by the angle calculation unit 15. 6 (A) to 6 (D) show output waveform diagrams of the sensor line 5A to 5D of the magnetic line sensor 5 when the rotating side member 1 is rotating, and the horizontal axes thereof represent the sensor lines 5A to 5D. The alignment position of the magnetic sensor elements 5a in 5D and the vertical axis indicate the strength of the detected magnetic field.
Now, assume that there are zero-cross positions at the positions X1 and X2 shown in FIG. 7 that are boundaries 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 rows 5A to 5D of the magnetic line sensor 5 have 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 rows 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 lateral length between the zero-cross positions X1 and X2.
When the zero cross positions X1 and X2 are 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.
Thus, since the calculated zero-cross position or et rotational angle of the magnetic field distribution, it is possible to improve the detection accuracy. Moreover, since angle information is acquired from a magnetic field pattern, the axis alignment of the rotation detection apparatus 3 becomes unnecessary, and attachment becomes easy.
[0020]
FIG. 8 shows an example in which the rotation detection device 3 of this embodiment is incorporated in a rolling bearing. This rolling bearing 20 has a rolling element 24 held by a cage 23 interposed between rolling surfaces of an inner ring 21 and an outer ring 22. The rolling element 24 is made of a ball, and the rolling bearing 20 is a deep groove ball bearing. A seal 25 that covers one end of the bearing space is attached to the outer ring 22.
The inner ring 21 into which the rotary shaft 10 is fitted is supported by the outer ring 23 via the rolling elements 24. The outer ring 23 is installed in a housing (not shown) of a bearing using device.
[0021]
A magnetism generating means mounting member 26 is attached to the inner ring 21, and the magnetism generating means 4 is attached to the magnetism generating means mounting member 26. The magnetism generating means mounting member 26 is provided so as to cover an inner diameter hole at one end of the inner ring 21, and a cylindrical portion 26 a provided on the outer peripheral edge is fitted to the outer peripheral surface of the shoulder portion of the inner ring 21, thereby Installed. Further, the side plate portion in the vicinity of the cylindrical portion 26a is engaged with the width surface of the inner ring 21, and the axial positioning is performed.
A sensor attachment member 27 is attached to the outer ring 22, and the semiconductor chip 9 in which the magnetic line sensor 5 and the angle calculation means 6 of FIG. 1 are integrated is attached to the sensor attachment member 27. An output cable 29 for taking out the output of the angle calculation means 6 is also attached to the sensor attachment member 27. The sensor mounting member 27 has an outer peripheral tip cylindrical portion 27a fitted to the inner diameter surface of the outer ring 22, and a flange portion 27b formed in the vicinity of the distal cylindrical portion 27a is engaged with the width surface of the outer ring 22 in the axial direction. Positioning has been made.
[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 in each sensor array 5A to 5D is 200, the length of each sensor array 5A to 5D. The length is 2.0 mm, and the size 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 considering that the outer diameter of a typical small-diameter bearing (model number # 608) is φ22 mm.
Although details are omitted, it is considered that the rotation detection 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 marked improvement in performance can be expected from a resolution of 3 °.
Further, if a wireless transmitter 31 and a receiver (not shown) such as a radio wave are provided adjacent to the semiconductor chip 9 as shown by a chain line in FIG. 1, the 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. This angle calculation means 6A is provided with a pulse conversion section 16 at the next stage of the angle calculation section 15 in the angle calculation means 6 of FIG. 4, and based on the angle information obtained by the angle calculation section 15, a detection signal as an incremental pulse signal. Is output. Specifically, as shown in FIG. 10, the rotation angle for one rotation (360 °) is divided into “0” section (black portion in FIG. 10) and “1” section (white portion in FIG. 10) for each predetermined angle. ) And is written in a storage means such as a ROM. The rotation angle θ obtained by the angle calculation unit 15 is collated with the data stored in the storage means. When the calculated rotation angle θ corresponds to the black portion in FIG. By outputting “1” respectively, an incremental pulse output is obtained from the angle calculation means 6A as the magnetism generation means 4 rotates.
[0024]
【The invention's effect】
The rotation detection device of the present invention can realize a small and highly accurate rotation detection device by combining 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 small devices.
Angle calculating means for is for calculating the angle by detecting the zero-cross position of the magnetic field distribution from the output of the magnetic line sensor, accuracy of the angular position detected can be expected. In addition, when the magnetic line sensor is arranged in a rectangular shape and the angle calculation means is arranged therein, each component can be arranged with high space efficiency, resulting in a more compact configuration. When the magnetic line sensor and the angle calculation means are integrated on a single semiconductor chip, further downsizing is possible, the reliability against disconnection and the like is improved, and the assembly operation of the rotation detection device is facilitated. .
Since the bearing with the rotation detection device of the present invention incorporates the rotation detection device of the present invention, a highly accurate rotation angle output can be obtained even if the bearing is miniaturized.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a conceptual configuration of a rotation detection device according to an embodiment of the present invention.
FIG. 2 is a plan view showing an arrangement example of magnetic line sensors and angle calculation means 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 angle calculation means in the rotation detection device.
FIG. 5 is a function explanatory diagram of a spatial filter unit in the angle calculation means.
FIG. 6 is a waveform diagram showing an output of a magnetic line sensor.
FIG. 7 is an explanatory diagram of angle calculation processing by an angle calculation unit.
FIG. 8 is a cross-sectional view showing an example of a rolling bearing provided with the rotation detection device.
FIG. 9 is a block diagram showing another configuration example of the angle calculation means.
FIG. 10 is an explanatory diagram for explaining processing of a pulse conversion unit in the angle calculation means.
FIG. 11 is a cross-sectional view of a conventional example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Rotation side member 2 ... Non-rotation side member 3 ... Rotation detection apparatus 4 ... Magnetic generation means 5 ... Magnetic line sensors 5A-5D ... Sensor row 6 ... Angle calculation means 7 ... Permanent magnet 8 ... Magnetic material 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 ... Center of rotation

Claims (9)

A magnetism generating means arranged on the rotation side member and having circumferential anisotropy around the rotation center, and arranged on the non-rotation side member facing the magnetism generation means in the axial direction of the rotation center, the magnetism generation means of the magnetic line sensor for detecting magnetism, e Bei and an angle calculating means for calculating a rotation angle of the magnetic generating element from an output of the magnetic line sensor, the magnetism generating means having the circumferential anisotropy, the permanent magnet Or the magnetic field distribution on the magnetic line sensor between the N pole and the S pole from the outputs of a plurality of magnetic sensor elements constituting the magnetic line sensor. A rotation detection device that obtains a zero-cross position that is a position that becomes a changing boundary and calculates the rotation angle from the zero-cross position . 2. The rotation detection device according to claim 1, wherein the angle calculation means calculates the zero-cross position by linear approximation from outputs of the plurality of magnetic sensor elements of the magnetic line sensor .   3. The rotation detection device according to claim 1, wherein the magnetic line sensor is arranged along each side of four sides of a virtual rectangle, and the number of magnetic line sensors on each side is at least one.   4. The rotation detection device according to claim 3, wherein the angle calculation means is arranged inside a rectangular arrangement of magnetic line sensors arranged on each side.   5. The rotation detection device according to claim 1, wherein the magnetic line sensor and the angle calculation unit are integrated on a single semiconductor chip. 6. The angle calculation means according to claim 1, wherein the angle calculating means includes an amplifying unit that amplifies the output of the magnetic line sensor, an A / D converting unit that digitizes the amplified analog output, and a digital output thereof. A spatial filter unit that removes noise from the output, a zero detection unit that detects the zero- cross position of the magnetic field distribution from the output of the spatial filter unit, and an angle calculation unit that calculates the rotation angle from the output of the zero detection unit Rotation detection device.   7. The rotation detection device according to claim 1, wherein the angle calculation means performs pulse conversion on the calculation result of the rotation angle and outputs a pulse.   8. The rotation detection device according to claim 1, wherein a transmitter that wirelessly transmits the angle information calculated by the angle calculation means is provided adjacent to the magnetic line sensor.   A bearing with a rotation detection device incorporating the rotation detection device according to any one of claims 1 to 7.

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