JP2006220529A - Detection device for absolute angle of rotation and torque - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device for detecting the absolute angle of multi-rotation and torque accurately and with high resolution, using a target of which magnetic poles linked with the rotational shaft with different polarity are magnetized alternately on the outer surface. <P>SOLUTION: Absolute angle of rotation and torque are detected accurately and with high resolution, having a simple constitution, having a first rotor 1 which has the first target 3 whose magnetic poles linked with the input shaft 2 with different polarity are magnetized alternately on the outer surface at equal intervals and has a multi-rotational gear; a second rotor 8 connected with the gear of the first rotor 1, rotating in lower speed than the first rotor 1 and arranged with a magnet 9 in the center; and a third rotor 4 which has the second target 6, whose magnetic poles linked with the output shaft 5 with different polarity are magnetized alternately on the outer surface with an equal interval and has a multi-rotational gear, and the first, second and third detecting means 11, 10 and 12 detecting those angles of rotation. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an absolute rotation angle and torque detection device used for vehicle power steering and the like, and more particularly to an absolute rotation angle and torque detection device capable of simultaneously detecting the absolute rotation angle and torque of a steering. is there.

  Conventionally, a method as shown in FIG. 9 is known as a method for detecting the rotation angle and torque. In FIG. 9, the gear portion 33 is attached to a rotation shaft (not shown) whose rotation angle is 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. Further, by attaching the mechanism according to this configuration to two shafts connected via a torsion bar, when the torque acts between the two shafts and a twist occurs between the shafts, the rotation of each shaft is performed. The amount of applied torque is detected by comparing the angles.

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 or torque detection sensor configured as described above, 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. In order to improve the resolution, 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. There was a problem. In addition, this rotation sensor can only detect the relative rotation angle and cannot detect the 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 and torque detection.

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

  According to a first aspect of the present invention, there is provided a gear that is connected to an input shaft, holds a first target having an equally spaced magnetic pole on the outer circumferential surface, and is capable of multiple rotations. A first rotating body having a first detecting means for detecting a rotation angle of the first rotating body, a first rotating body connected to a gear of the first rotating body and rotating at a lower speed than the first rotating body; The second rotating body having a magnet disposed in the part, the second detecting means for detecting the rotation angle of the second rotating body, and the output shaft are connected to the outer peripheral surface at equal intervals and alternately polarized. A structure comprising a third rotating body holding a second target magnetized with different magnetic poles and having a gear capable of multiple rotations, and third detecting means for detecting the rotation angle of the third rotating body The absolute angle of rotation is detected by the first detecting means, and the coarse angle is detected by the second detecting means. The absolute rotation angle is detected, and the absolute rotation angle of the first rotating body is detected from these absolute rotation angles, and the absolute rotation angle and torque can be detected with high accuracy and high resolution with a simple configuration. The effect that it can be obtained.

  According to the second aspect of the present invention, the absolute rotation angle obtained from the first detection means and the second detection means are obtained in particular by making the number of magnetic poles of the first target and the second target the same. By calculating the difference between the absolute rotation angle and the absolute rotation angle, it is possible to obtain an effect that the absolute rotation angle and the torque can be detected with high accuracy and high resolution with a simple configuration.

  According to a third aspect of the present invention, the first, second and third detection means are constituted by magnetic detection elements, whereby the first, second and third rotating bodies are non-contacted. Since the absolute rotation angle can be detected, it is possible to improve the durability and reliability of the apparatus.

  The invention described in claim 4 of the present invention particularly has a configuration in which a torsion bar is provided between the input shaft and the output shaft, so that the torsion angle corresponding to the torque can be expanded. The effect of increasing the resolution of torque detection can be obtained.

  The invention according to claim 5 of the present invention has a non-volatile memory for storing the sensitivity of the sine wave signal and cosine wave signal output from the first, second and third detection means, After incorporating the second rotating body, each time the power is turned on, the sine wave signal and the cosine wave signal are corrected with the respective sensitivities. There is an effect that the rotation angle of the rotating body can be detected without generating an angle detection error due to variations.

  The invention according to claim 6 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 7 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 8 of the present invention provides a 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, whereby 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 9 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 the 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 and torque detection device of the present invention has the effect of being able to perform multi-rotation absolute rotation angle detection and torque detection 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 and torque detection device according to an embodiment of the present invention, FIG. 2 is a diagram showing rotation angle detection signals of first and third magnetic detection elements, and FIG. FIG. 4 is a circuit block diagram of an absolute rotation angle / torque detection device. 5 is a diagram showing ideal and actual values of absolute rotation angles of the first and third rotating bodies, FIG. 6 is a torque detection characteristic diagram, and FIG. 7 is a rotation angle calculation output and absolute rotation of each element in the CPU. FIG. 8 is an output diagram of the first, second, and third magnetic detection elements.

  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 first 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 third rotator 4 is a rotator having multi-rotatable gears fitted and connected to the output shaft 5. The second target 6 is held by the third rotating body 4, and magnetic poles having different polarities are alternately magnetized on the outer peripheral surface at equal intervals. The torsion bar 7 is arranged on a concentric axis between the input shaft 2 and the output shaft 5. 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 located at a position facing the first target 3, and the second magnetic detection element (detection means) 10 is located at a position facing the magnet 9. Detection means) 12 are arranged at positions facing the second target 6 and detect the direction of the magnetic field. The first, second, and third magnetic detection elements 11, 10, and 12 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 number of magnetic poles of the first target 3 and the second target 6 is the same. The number of magnetic poles is determined by the maximum torque detection amount and the torsion bar constant. For example, when the maximum torque detection is ± 12 N · m and the torsion bar constant is 2 N · m / deg, the number of magnetic poles is 30 and is determined as N pole 15 and S pole 15. In this case, it is 12 deg per pole.

  A case where a magnetoresistive element (hereinafter referred to as an MR element) is used as the first, second, and third magnetic detection elements 11, 10, and 12 will be described. Each magnetic detection element outputs a sine wave signal and a cosine wave signal in analog with respect to the magnetic field change. When the first and third magnetic detection elements 11 and 12 detect magnetic field changes of the first and second targets 3 and 6, since one cycle of a sine wave and cosine wave signal is output for one pole, Sine wave and cosine wave signal outputs can be obtained by the number of magnetic poles per rotation. This output is amplified to a specified amplitude by an amplifier and processed through an A / D converter in a microcomputer (hereinafter referred to as a CPU) to rotate the first and second targets 3 and 6, that is, first, The absolute rotation angle of the third rotating bodies 1 and 4 can be calculated. The waveform is shown in FIG. In the upper diagram of FIG. 2, the horizontal axis indicates the absolute rotation angle of the input shaft 2 and the output shaft 5, and the vertical axis indicates the sine wave and cosine wave signals from the first and third magnetic detection elements 11 and 12. Show. In the lower diagram of FIG. 2, the horizontal axis indicates the absolute rotation angle of the input shaft 2 and the output shaft 5, and the vertical axis indicates the absolute rotation angle in the calculation process of the CPU of the first and third rotating bodies 1 and 4. Show.

  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 indicates the absolute rotation angle of the input shaft 2 and the output shaft 5, and the vertical axis indicates 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 output shaft 5, 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, second, and third magnetic detection elements 11, 10, and 12 are input to the CPU 14 through the amplification unit 16, and are processed to output an absolute rotation angle and torque. To do. The CPU 14 is connected to an EEPROM 15 which is a nonvolatile memory.

  In the upper diagram of FIG. 5, the horizontal axis indicates the absolute rotation angle of the input shaft 2 and the output shaft 5, and the vertical axis indicates the fine absolute rotation angle difference obtained from the first and third rotating bodies 1, 4. ing. The dotted line indicates the ideal value of the absolute rotation angle of the first and third rotating bodies 1 and 4, and the solid line indicates the actual value of the absolute rotation angle obtained from the first and third rotating bodies 1 and 4.

  In the lower diagram of FIG. 5, the horizontal axis indicates the absolute rotation angle of the input shaft 2 and the output shaft 5, 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.

  FIG. 6 is a diagram illustrating torque detection characteristics, where the horizontal axis indicates the absolute rotation angle of the input shaft 2 and the output shaft 5, and the vertical axis indicates the absolute rotation angle difference between the first rotating body 1 and the third rotating body 4. Is shown. If the absolute rotation angle of the first rotating body 1 is X, the absolute rotation angle of the third rotating body 4 is Y, and the torsion bar constant is T, the detected torque can be calculated by (X−Y) × T. .

  Next, a method for calculating the torque applied to the torsion bar will be described.

  In FIG. 1, when the input shaft 2, the torsion bar 7, and the output shaft 5 that are the same rigid body rotate, the first rotating body 1 fitted and connected to the input shaft 2 rotates. When the first rotating body 1 rotates, the first target 3 held by the first rotating body 1 rotates. As a result, the first magnetic detection element 11 disposed at a position facing the first target 3 detects a change in the magnetic field, and the CPU performs an arithmetic process on the output to calculate the absolute rotation angle of the first rotating body 1. Is calculated. On the other hand, the third rotating body 4 fitted and connected to the output shaft 5 also rotates. When the third rotating body 4 rotates, the second target 6 held by the third rotating body 4 rotates. As a result, the third magnetic detection element 12 arranged at a position facing the second target 6 detects a change in the magnetic field, and the CPU calculates the output thereof to perform an absolute rotation angle of the third rotating body 4. Is calculated. The torque can be calculated by taking the difference in absolute rotation angle between the first rotating body 1 and the third rotating body 4 and multiplying this by the torsion bar constant.

  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.

  An output is obtained by detecting a change in the magnetic field with respect to the rotation of the first rotating body 1 by the first magnetic detection element 11 disposed at a position facing the first target 3 held by the first rotating body 1. Changes. 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. 7 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, second, and third magnetic detection elements 11, 10, 12 and the amplifying unit 16 and preventing the occurrence of a rotation angle detection error during operation will be described with reference to FIGS. This will be described with reference to FIG.

  In FIG. 1, when the first rotating body 1 rotates, the first target 3 also rotates. The magnetic field changes due to the rotation of the first 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. 8 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. 8, when 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 amplifying unit, the accuracy of the calculated arctangent signal decreases. 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 rotation angle is calculated, the arc tangent signal is calculated and rotated by operating so that the maximum and minimum levels of the sine wave signal 24 and the cosine wave signal 23 coincide with the stored sensitivity. Find the angle.

  Further, when the maximum and minimum values of the outputs of the first and second magnetic detection elements 11 and 10 in FIG. 8 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 and torque detection device of the present invention can detect the absolute rotation angle and torque with high accuracy and high resolution with a simple configuration. Therefore, the absolute rotation angle and torque detection used in vehicle power steering and the like. Useful for device applications.

FIG. 1 is a basic configuration diagram of an absolute rotation angle and torque detection device according to an embodiment of the present invention. The figure showing the rotation angle detection signal of the 1st, 3rd 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 absolute rotation angle and torque 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, 3rd rotary body in embodiment of this invention Torque detection characteristic diagram in the embodiment of the present 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, second, and third magnetic detection elements in the embodiment of the present invention Configuration diagram for detecting conventional rotation angle and torque

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st rotary body 2 Input shaft 3 1st target 4 3rd rotary body 5 Output shaft 6 2nd target 7 Torsion bar 8 2nd rotary body 9 Magnet 10 2nd magnetic detection element 11 1st Magnetic detection element 12 Third magnetic detection element 13 Substrate 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 (9)

A first rotating body connected to the input shaft and holding a first 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 of the rotating body, and a second rotating body connected to the gear of the first rotating body and rotating at a lower speed than the first rotating body, and having a magnet disposed at the center. And a second detection means for detecting the rotation angle of the second rotating body, and a second target that is connected to the output shaft and is alternately magnetized with magnetic poles of different polarities at equal intervals on the outer peripheral surface An absolute rotation angle and torque detection device comprising a third rotating body having a multi-rotating gear and a third detecting means for detecting the rotation angle of the third rotating body. The number of magnetic poles of the first target and the second target is the same, and the calculation is performed based on a differential between the absolute rotation angle of the first rotating body and the absolute rotation angle of the third rotating body. The absolute rotation angle and torque detection device described in 1. 2. The absolute rotation angle and torque detection device according to claim 1, wherein the first, second and third detection means are constituted by magnetic detection elements arranged at positions facing the first and second targets and the magnet. The absolute rotation angle and torque detection device according to claim 1, wherein a torsion bar is provided between the input shaft and the output shaft. A non-volatile memory for storing the sensitivity of the sine wave signal and the cosine wave signal output from the first, second and third detection means, and after incorporating the first and second rotating bodies, 2. The absolute rotation angle and torque detection device according to claim 1, wherein the sine wave signal and the cosine wave signal are corrected at the respective sensitivities at the time of input. 6. The absolute rotation angle and torque detection device according to claim 5, further comprising means for confirming whether or not the sensitivity of each magnetic detection element is within a specified value when storing the sensitivity. 6. The absolute rotation angle and torque detection device according to claim 5, 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. 6. The absolute rotation angle and torque detection device according to claim 5, 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. 5. The absolute rotation angle and torque detection device according to 5.

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