JP2006220530A - Device for detecting absolute angle of rotation - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device for detecting absolute angle of rotation accurately and with high resolution by using a target of which magnetic poles linked with the rotational shaft with different polarity are magnetized alternatingly on the outer surface. <P>SOLUTION: Absolute angle of rotation is detected accurately and with high resolution with simple configuration having a first rotator 1 which has a target 3 whose magnetic poles linked with the input shaft 2 with different polarity are magnetized alternatingly on the outer surface with an equal interval and has a multi-rotational gear, a second rotator 8 connected with the gear of the first rotator 1, rotating in lower speed than the first rotator 1 and arranged with a magnet 9 in the center, and the first, second and third detecting means 11, 10 and detecting those angles of rotation. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a rotation angle detection device used for a vehicle body control system of a vehicle, and more particularly to a multi-turn absolute handle rotation angle detection device.

  Conventionally, a method as shown in FIG. 8 is known as a method for detecting the rotation angle. In FIG. 8, the gear portion 33 is attached to a rotation shaft (not shown) whose rotation angle is desired to be detected via an engagement spring 34. The gear portion 33 meshes with a gear portion 36 having a code plate 35 having a plurality of magnetic poles magnetized on the outer peripheral end face, and the magnetic pole provided on the code plate 35 moves in accordance with the rotation of the rotating shaft to be detected. The rotation angle is detected by counting the number of the magnetic poles by the detection element 37 provided facing the outer peripheral end face.

As prior art document information relating to the invention of this application, for example, Patent Document 1 is known.
Japanese Patent Laid-Open No. 11-194007

  However, in the rotation angle sensor configured in this way, the rotation angle of the shaft is detected by counting the number of movements of a plurality of magnetic poles arranged on the outer peripheral end surface of the code plate, so that the resolution of the detection angle is improved. In order to achieve this, it is necessary to reduce the size of the magnetized magnetic pole, and since the rotation of the code plate and the rotation of the shaft are via gears, it is difficult to improve detection accuracy due to backlash or the like. It was. In addition, this rotation sensor can only detect a relative rotation angle, and cannot detect an absolute rotation angle.

  The present invention solves the above-mentioned problems, and uses a target that is connected to a rotating shaft and magnetized with magnetic poles having different polarities alternately on the outer peripheral surface, and performs high-precision, high-resolution, multi-turn absolute rotation. An object of the present invention is to provide an apparatus that performs angle detection.

  In order to achieve the above object, an absolute rotation angle detection device of the present invention has the following configuration.

  According to a first aspect of the present invention, there is provided a first gear having a gear which can be connected to an input shaft and has a multi-rotation gear which holds a target in which magnetic poles having different polarities are alternately magnetized at equal intervals on an outer peripheral surface. A rotating body of the first rotating body, a first detecting means for detecting a rotation angle of the first rotating body, and a gear connected to the gear of the first rotating body and rotating at a lower speed than the first rotating body. Is arranged, and a second detection means for detecting the rotation angle of the second rotation body, and a fine absolute rotation angle is detected by the first detection means. The second detection means detects a rough absolute rotation angle, detects the multiple rotation absolute rotation angle of the first rotating body from these absolute rotation angles, and achieves high accuracy and high resolution with a simple configuration. The effect that the absolute rotation angle can be detected is obtained.

  According to a second aspect of the present invention, the first and second detection means are constituted by magnetic detection elements arranged at positions facing the target and the magnet, whereby the first and first detection means are contactless. Since the absolute rotation angle of the rotating body 2 can be detected, the effect of improving the durability and reliability of the apparatus can be obtained.

  According to a third aspect of the present invention, there is provided a non-volatile memory for storing the sensitivity of the sine wave signal and the cosine wave signal output from the first and second detection means. After incorporating the rotating body, each time the power is turned on, the sine wave signal and the cosine wave signal are corrected with the respective sensitivities. The angle due to the sensitivity variation of the detection element and the detection element amplification unit There is an effect that the rotation angle of the rotating body can be detected without generating a detection error.

  The invention according to claim 4 of the present invention has means for confirming whether or not the sensitivity of each magnetic detection element is within a specified value when storing the sensitivity of each magnetic detection element. Due to variations and the like, it is possible to obtain an effect that the signal can be removed even if a signal whose sensitivity is outside the reference range is input.

  The invention according to claim 5 of the present invention includes means for confirming whether or not the center of the amplitude of the output signal is within a specified value when storing the sensitivity of each magnetic detection element. Even if a signal having an amplitude center outside the reference range is input due to variations in the characteristics of the detection elements, an effect of being able to be removed is obtained.

  The invention according to claim 6 of the present invention provides a means for detecting a sine wave signal and a cosine wave signal a plurality of times when storing the sensitivity of each magnetic detection element, so that a sine wave signal due to noise or the like, Even if there is an abnormality in the cosine wave signal, it is possible to reduce the detection error.

  The invention according to claim 7 of the present invention has means for determining an arbitrary specific position of each magnetic detection element, and by storing the values of the sine wave signal and the cosine wave signal at that position, it is constant. An effect is obtained that an absolute rotation angle from a specific position within the rotation range can be detected.

  The absolute rotation angle detection device of the present invention has the effect of being able to detect multiple rotation absolute rotation angles with high accuracy and high resolution by adopting the above configuration.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  FIG. 1 is a basic configuration diagram of an absolute rotation angle detection device according to an embodiment of the present invention, FIG. 2 is a diagram showing a rotation angle detection signal of a first magnetic detection element, and FIG. 3 is a rotation angle of a second magnetic detection element FIG. 4 is a circuit block diagram of the absolute rotation angle detection device. FIG. 5 is a diagram showing ideal and actual values of absolute rotation angles of the first and second rotating bodies, FIG. 6 is a diagram showing rotation angle calculation output and absolute rotation angle in the CPU, and FIG. The output figure of a 2nd magnetic detection element is shown.

  In FIG. 1, a first rotating body 1 is a rotating body having a multi-rotatable gear that is fitted and connected to an input shaft 2. The target 3 is held by the first rotating body 1, and magnetic poles having different polarities are alternately magnetized on the outer peripheral surface at equal intervals. The second rotator 8 is a rotator provided so as to be engaged with the gear of the first rotator 1, and a magnet 9 is disposed at the center thereof. The first magnetic detection element (detection means) 11 is disposed at a position facing the target 3, and the second magnetic detection element (detection means) 10 is disposed at a position facing the magnet 9, and detects the magnetic field direction. The first and second magnetic detection elements 11 and 10 are installed on the substrate 13. The gears of the first rotating body 1 and the gears of the second rotating body 8 are connected to each other, and the second rotating body 8 speeds by the ratio of the number of teeth of each gear when the first rotating body 1 rotates. Rotate with.

  The case where a magnetoresistive element (hereinafter referred to as an MR element) is used as the first and second magnetic detection elements 11 and 10 will be described. From each magnetic detection element, a sine wave signal and a cosine wave signal are output in analog to the magnetic field change. When the magnetic field change of the target 3 is detected by the first magnetic detection element 11, a sine wave and cosine wave signal of one cycle is output for one pole, so that the sine wave and cosine are equivalent to the number of magnetic poles per rotation. A wave signal output can be obtained. This output is amplified to a specified amplitude by an amplifier, and arithmetic processing is performed via an A / D converter in a microcomputer (hereinafter referred to as “CPU”) to determine the rotation of the target 3, that is, the absolute rotation angle of the first rotating body 1. Can be calculated. The waveform is shown in FIG. 2, the horizontal axis indicates the absolute rotation angle of the input shaft 2, and the vertical axis indicates the sine wave and cosine wave signals from the first magnetic detection element 11. In the lower diagram of FIG. 2, the horizontal axis indicates the absolute rotation angle of the input shaft 2, and the vertical axis indicates the absolute rotation angle in the calculation process of the CPU of the first rotating body 1.

  The second magnetism detecting element 10 detects a change in the magnetic field of the magnet 9 disposed at the center of the second rotating body 8, and outputs a sine wave signal and a cosine wave signal of two cycles for one rotation of the magnet 9. . This output can be processed by the CPU, and the absolute rotation angle of the second rotating body 8 can be calculated. The waveform is shown in FIG. In the upper diagram of FIG. 3, the horizontal axis represents the absolute rotation angle of the input shaft 2, and the vertical axis represents the sine wave and cosine wave signals from the second magnetic detection element 10. In the lower diagram of FIG. 3, the horizontal axis indicates the absolute rotation angle of the input shaft 2, and the vertical axis indicates the absolute rotation angle in the calculation process of the CPU of the second rotating body 8.

  In FIG. 4, output signals from the first and second magnetic detection elements 11 and 10 are input to the CPU 14 via the amplifier 16 and are subjected to arithmetic processing to output an absolute rotation angle. The CPU 14 is connected to an EEPROM 15 which is a nonvolatile memory.

  In the upper diagram of FIG. 5, the horizontal axis represents the absolute rotation angle of the input shaft 2, and the vertical axis represents the fine absolute rotation angle obtained from the first rotating body 1. The dotted line indicates the ideal value of the absolute rotation angle of the first rotating body 1, and the solid line indicates the actual value of the absolute rotation angle obtained from the first rotating body 1.

  In the lower part of FIG. 5, the horizontal axis indicates the absolute rotation angle of the input shaft 2, and the vertical axis indicates the coarse absolute rotation angle obtained from the second rotating body 8. The dotted line represents the ideal value of the absolute rotation angle of the second rotating body 8, and the solid line represents the actual value of the absolute rotation angle obtained from the second rotating body 8.

  Next, a method for detecting the rotation angle of the rotating body will be described.

  In FIG. 1, when the first rotating body 1 rotates, the second rotating body 8 is rotated by the gear of the second rotating body 8 connected to the gear of the first rotating body 1. When the number of teeth of the gear of the first rotating body 1 is a and the number of teeth of the gear of the second rotating body 8 is b, the second rotating body 8 is multiplied by a / b with respect to the first rotating body 1. It rotates at a speed of. At this time, the gears rotate at a sufficiently lower speed than the first rotating body 1 by appropriately selecting the number of gear teeth a and b.

  The first magnetic detection element 11 disposed at a position facing the target 3 held by the first rotating body 1 detects the change in the magnetic field with respect to the rotation of the first rotating body 1 to change the output. . On the other hand, the second magnetic detection element 10 disposed opposite to the second rotating body 8 having the magnet 9 disposed at the center portion causes the second magnetic detection element 10 to move when the second rotating body 8 rotates. The output changes by detecting the magnetic field change that penetrates. Further, the outputs of the first magnetic detection element 11 and the second magnetic detection element 10 are input via an A / D converter in the CPU. From the output of the second magnetic detection element 10, a rough absolute angle detection is made of how many times the second rotating body 8 is from the initial position, and from the output of the first magnetic detection element 11, the first rotating body 1 is detected. An absolute angle with a fine rotation angle is detected, and an absolute rotation angle is calculated from the output and output.

  FIG. 6 shows the rotation angle calculation output of each magnetic detection element in the CPU and the absolute rotation angle of the rotation angle detector. The output 19 is the rotation angle calculation output of the first magnetic detection element 11, the output 20 is the rotation angle calculation output of the second magnetic detection element 10, the output 21 is the calculated absolute rotation angle of the rotation angle detector, and the output 22 is the ideal absolute Indicates the rotation angle.

  Next, a method for suppressing the variation in sensitivity of the first and second magnetic detection elements 11 and 10 and the amplifying unit 16 and preventing the occurrence of a rotation angle detection error during operation will be described with reference to FIGS. To do.

  In FIG. 1, when the first rotating body 1 rotates, the target 3 also rotates. The magnetic field is changed by the rotation of the target 3, and this magnetic field change is detected by the first magnetic detection element 11. The first magnetic detection element 11 outputs a sine wave signal 24 and a cosine wave signal 23 in response to this magnetic field change. FIG. 7 shows these output signals. These signals are input to the CPU via an amplifier, and an arctangent signal is calculated from the sine wave signal 24 and the cosine wave signal 23. However, as shown in FIG. 7, if the sine wave signal level 27 and the cosine wave signal level 26 are slightly different due to variations in sensitivity of the magnetic detection element and the amplification unit, the accuracy of the calculated arctangent signal is lowered. Therefore, only when the switch 29 shown in FIG. 4 is turned on to enter the sensitivity memory mode, the first rotating body 1 is rotated so that the second rotating body 8 rotates 180 degrees or more, and the sine wave signal 24 and the cosine wave signal. The maximum and minimum levels of 23 are calculated, and each signal level (sensitivity) is stored in a nonvolatile memory (EEPROM) 15. Next, when the switch 29 is turned OFF and the steering angle value is calculated, the arc tangent signal is calculated by operating the sine wave signal 24 and the cosine wave signal 23 so that the maximum and minimum levels coincide with each other according to the stored sensitivity. Find the rudder angle value.

  Further, when the maximum and minimum values of the outputs of the first and second magnetic detection elements 11 and 10 in FIG. 7 are not within the reference range 28, the output does not change due to temperature characteristics or the necessary resolution can be obtained. Not happening. Therefore, it is possible to prevent erroneous output by confirming using means (not shown) for confirming that the output has the maximum value and the minimum value within the reference range 28. By checking the amplitude centers of the outputs of the first and second magnetic detection elements 11 and 10 with means for comparing and checking (not shown), it is possible to prevent erroneous output due to characteristic variations. Further, at this time, it is possible to prevent erroneous output with higher accuracy by inputting multiple times each time and taking an average value or taking an average value excluding the maximum and minimum values.

  Further, by storing the outputs of the first magnetic detection element 11 and the second magnetic detection element 10 at an arbitrary specific position, it is possible to detect the absolute rotation angle from the arbitrary specific position. At this time, if a signal indicating the specific position is transmitted by an electrical signal as in the specific position determination signal line 31 of FIG. 4, the specific position can be determined without mechanical operation. Furthermore, if an electric signal is read and checked a plurality of times or sent as a serial signal, it can be removed if an erroneous signal is input due to noise or the like. Note that the same effect can be obtained even when the input / output of the specific position determination signal line 31 is switched to that of the output signal line 32 and the same terminal is used.

  The absolute rotation angle detection device of the present invention can detect an absolute rotation angle with high accuracy and high resolution with a simple configuration, and is therefore useful for application to an absolute rotation angle used in vehicle power steering and the like. is there.

1 is a basic configuration diagram of an absolute rotation angle detection device according to an embodiment of the present invention. The figure showing the rotation angle detection signal of the 1st magnetic detection element in embodiment of this invention The figure showing the rotation angle detection signal of the 2nd magnetic detection element in embodiment of this invention Circuit block diagram of an absolute rotation angle detection device in an embodiment of the present invention The figure which shows the ideal value and ability value of the absolute rotation angle of the 1st rotary body in embodiment of this invention The figure showing the rotation angle calculation output of each element in CPU in embodiment of this invention, and the absolute rotation angle of a rotation angle detection apparatus Output diagram of first and second magnetic detection elements in the embodiment of the present invention Configuration diagram for detecting the conventional rotation angle

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st rotary body 2 Input shaft 3 Target 8 2nd rotary body 9 Magnet 10 2nd magnetic detection element 11 1st magnetic detection element 14 Microcomputer (CPU)
15 Nonvolatile memory (EEPROM)
16 Amplifying unit 19 Rotation angle calculation output of first magnetic detection element 20 Rotation angle calculation output of second magnetic detection element 21 Calculated absolute rotation angle of rotation angle detection device 22 Ideal absolute angle 23 Cosine wave signal 24 Sine wave signal 26 Cosine wave signal level 27 Sine wave signal level 28 Reference range 29 Switch 31 Specific position determining signal line 32 Output signal line

Claims (7)

A first rotating body connected to the input shaft and holding a target having magnetic poles of different polarities alternately spaced at equal intervals on the outer peripheral surface and having a multi-rotating gear; A first detecting means for detecting a rotation angle, a second rotating body connected to the gear of the first rotating body, rotating at a lower speed than the first rotating body, and having a magnet disposed at the center, and An absolute rotation angle detection device comprising second detection means for detecting the rotation angle of the second rotating body. The absolute rotation angle detection device according to claim 1, wherein the first and second detection means are constituted by magnetic detection elements arranged at positions facing the target and the magnet. A non-volatile memory for storing the sensitivity of the sine wave signal and the cosine wave signal output from the first and second detection means, and after the first and second rotating bodies are incorporated, The absolute rotation angle detection device according to claim 1, wherein the sine wave signal and the cosine wave signal are corrected with the respective sensitivities. The absolute rotation angle detection device according to claim 3, further comprising means for confirming whether or not the sensitivity of each magnetic detection element is within a specified value when storing the sensitivity. 4. The absolute rotation angle detection device according to claim 3, further comprising means for confirming whether or not the center of the amplitude of the output signal is within a specified value when the sensitivity of each magnetic detection element is stored. The absolute rotation angle detection device according to claim 3, further comprising means for detecting a sine wave signal and a cosine wave signal a plurality of times when the sensitivity of each magnetic detection element is stored. A means for determining an arbitrary specific position of each magnetic detection element, storing values of a sine wave signal and a cosine wave signal at the position, and detecting an absolute rotation angle from the specific position. 4. The absolute rotation angle detection device according to 3.

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