JP2007271372A - Rotation sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotation sensor capable of preventing detection from being affected by the backlash of gears or the like as much as possible, and excellent in detection precision. <P>SOLUTION: The rotation sensor measures a rotation angle of a rotator 50 to be measured by using measuring rotors other than the rotator, and is provided with a first measuring rotator 10 which rotates with a number of revolutions approximately the same as that of the rotator to be measured, and a second measuring rotator 20 which rotates being interlocked with the first body by a number of revolutions smaller than that of the first body. The rotator to be measured and the first measuring rotator are united with gears, the first measuring rotator and the second rotator are united with gears, and the second measuring rotator intermittently rotates with the rotation of the first measuring rotator. In each measuring rotor, a permanent magnet having a radial magnetic field is arranged at the center, and moreover a predetermined number of magnetic field detecting elements are arranged respectively at spots where changes in the radial direction in a magnetic field generated by each magnet can be detected, independently of the rotation of the measuring rotators. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a rotation sensor used for detecting a rotation angle of a rotating body.

  For example, a so-called rotation sensor is used to detect a rotation angle of a handle attached to a rotating shaft such as a steering shaft of an automobile and integrated with the shaft.

  And the technique which measures the rotation angle of the target object rotated 360 degrees or more using two rotary bodies other than the said target object is disclosed by patent document 1, for example.

Such a rotation sensor includes a main rotating body having a large number of teeth and two sub-rotating bodies having a smaller number of teeth than the main rotating body and one difference in the number of teeth. In addition, a sensor for detecting the rotation angle is provided in each sub-rotor, and the rotation angles of the two sub-rotators are respectively measured. Then, the rotation angle of the main rotor is obtained from the rotation angle of each sub-rotator detected by the sensor.
Japanese National Patent Publication No. 11-500828 (page 6-7, FIG. 1)

  The rotation sensor described in Patent Document 1 detects the rotation angle of an object based on a phase difference between two rotating bodies that mesh with the object with a gear. Specifically, the rotation angle of the first sub-rotor and the rotation angle of the second sub-rotor are measured based on an angle sensor provided in each sub-rotor. The predetermined coefficient is determined by the periodicity of the angle sensor, the number of teeth of the first sub-rotating body, the number of teeth of the second sub-rotating body that differs from the number of teeth of the first sub-rotating body by one, and these constants. And the rotation angle of the main rotor is obtained from the coefficient, constant, and measured value. However, in such a rotation sensor that meshes with each other via a gear and detects the rotation angle of the main rotor by the phase difference between the main rotor and the three rotors, the backlash of the gear is Between the main rotating body and the first sub-rotating body, and between the main rotating body and the second sub-rotating body, and each affects as a rotation angle error. That is, since the gear backlash between the three rotating bodies is superimposed and it is easy to affect the detection accuracy of the main rotating body, it is difficult to increase the detection accuracy.

  An object of the present invention is to provide a rotation sensor that is not affected by the backlash of a gear as much as possible and has excellent detection accuracy.

In order to solve the above-mentioned problems, a rotation sensor according to the present invention is a rotation sensor that measures a rotation angle of a rotating body to be measured using a measuring rotating body other than the rotating body to be measured.
A first measurement rotating body that rotates at approximately the same rotational speed as the measurement rotating body in conjunction with the measurement rotating body, and a rotation that rotates in conjunction with the first measurement rotating body. A second measuring rotator whose number is smaller than the first measuring rotator,
The rotating body for measurement and the first rotating body for measurement are connected by a gear,
The second measuring rotator is composed of a Geneva gear, and rotates intermittently with the rotation of the first measuring rotator.
A permanent magnet having a radial magnetic field is arranged at the center of each of the first measuring rotating body and the second measuring rotating body, and further, a change in the radial direction of the magnetic field generated by each permanent magnet can be detected. A predetermined number of magnetic field detection elements are respectively arranged at different positions independently of the rotation of the first and second rotating bodies for measurement,
The rotation angle of the rotation body to be measured is measured by detecting the rotation angle of the first measurement rotation body and the rotation number of the second measurement rotation body using the output of the magnetic field detection element. It is said.

  A rotation sensor according to a second aspect of the present invention is the rotation sensor according to the first aspect, wherein the magnetic detection element is a Hall element.

  The rotation sensor according to claim 3 of the present invention is the rotation sensor according to claim 1 or 2, wherein the magnetic detection element is a magnetoresistive element (MR element).

  By using such a rotation sensor, it is not necessary to take a method of detecting the rotation speed by the phase difference between the three rotating bodies as in the conventional rotation sensor, and without being affected by the backlash of the gear as much as possible. Thus, a rotation sensor with high detection accuracy can be obtained.

  In addition, by using a Hall element or a magnetoresistive element (MR element) as the magnetic detection element, a rotation sensor with high detection accuracy can be easily realized.

  According to the present invention, it is possible to provide a rotation sensor that is not affected by gear backlash as much as possible and has excellent detection accuracy.

  Hereinafter, a rotation sensor according to an embodiment of the present invention will be described with reference to the drawings. In this description, a case will be described in which a rotation angle of a steering wheel is detected by attaching the rotation sensor to a steering shaft in an automobile steering device. Therefore, the absolute rotation angle in the range of −900 ° to + 900 ° that is the rotation range of the steering shaft is obtained by the rotation sensor according to the present embodiment.

  FIG. 1 is a plan view schematically showing the internal structure of a rotation sensor according to an embodiment of the present invention. FIG. 2 shows a schematic block configuration of the rotation sensor in the present embodiment.

  As shown in FIGS. 1 and 2, a rotation sensor 1 according to an embodiment of the present invention is attached to a rotating shaft S, and a main rotor 50 having a primary gear formed around it, and a main rotor 50. A gear having the same number of teeth as the number of teeth of the main rotor 50 is formed on the entire circumference so as to rotate at the same number of rotations, and the first rotation for measurement in which this gear and the gear of the main rotor 50 are always meshed. A body 10, a second measuring rotor 20 composed of a Geneva gear for measuring the number of revolutions of the first measuring rotor 10, and housing and holding these rotors 10, 20, 50 and from the outside The case 30 is provided to block the influence of the magnetic field. The first measurement rotator 10 and the second measurement rotator 20 generate a magnetic field in the radial direction of each of the rotators 10 and 20 and the strength of the magnetic field changes in the circumferential direction of the rotator. The permanent magnets 15 and 25 are arranged at the centers of the respective measurement rotating bodies 10 and 20.

  Further, a magnetic field detection element arrangement substrate 40 is fixed to the case 30, and the permanent magnets 15 arranged on the first measurement rotary body 10 and the second measurement rotary body 20 are disposed at predetermined positions on the case. Magnetic field detection elements 31 to 34 and 36 to 39 each capable of detecting a change in the radial direction of the magnetic field generated by each of the four magnetic field detection elements adjacent to each other in the circumferential direction of each of the measurement rotating bodies 10 and 20 are each 90 °. It is arranged to make an angle. As the magnetic field detection elements 31 to 34 and 36 to 39, Hall elements, magnetoresistive elements (MR elements), or the like can be used. In practice, either one can be used. However, when a Hall element is used, the element itself can detect not only the magnitude component of the magnetic field but also the direction component, so the number of elements can be reduced. There are also advantages. Hereinafter, in the present embodiment, a case where a Hall element is used as the magnetic field detection element will be described.

  That is, the first measuring rotating body 10 of the rotation sensor 1 of the present embodiment is rotated with a primary gear (not shown) of the main rotating body 50 at a rotation ratio of approximately 1: 1 with a secondary gear (not shown). Z). The rotation transmission error due to this configuration is mainly caused by the backlash between the gears. However, in the rotation sensor 1 of the present embodiment, the backlash between the gears occurs only between the primary gear and the secondary gear. Since it is not affected by the backlash between the other gears, as a result, it is not as affected by the backlash as the rotation sensor described in Patent Document 1.

  Further, the center of the first measuring rotator 10 is provided with a permanent magnet 15 which generates a magnetic field in the radial direction of the rotator and whose magnetic field strength changes in the circumferential direction of the rotator. The output signals of the four Hall elements 31 to 34 arranged in the circuit are processed by a microcomputer (not shown), and the first measuring rotating body 10, that is, the rotating body 50 to be measured, has a small angle of 0 ° to 360 °. The angle is detected with a required resolution (for example, 0.1 °, 0.5 °, etc.).

  Further, a notch portion formed around a Geneva gear (schematically shown in FIG. 1), which is a second measuring rotating body 20 described later, at a predetermined circumferential position of the first measuring rotating body 10. A feed pin 11 that intermittently engages with 20a to 20e is provided, and the second measuring rotating body 20 that is a Geneva gear is intermittently provided according to each rotation of the first measuring rotating body 10 as shown in FIG. To be sent.

  Note that the first measurement rotator 10 includes only two Hall elements instead of the above-described embodiment, uses these differential signals, and depends on the DC level and temperature of the sine wave signal to ensure detection accuracy. It is also possible to calculate the small angle of the first measurement rotating body 10 by suppressing the fluctuation as small as possible.

  Accordingly, at least two Hall elements may be arranged around the first measurement rotating body 10 at a predetermined interval in the circumferential direction excluding the opposing arrangement of 180 °, and there are not necessarily four circumferential directions as in the present embodiment. There is no need to arrange a Hall element. In this case, a magnetoresistive element (MR element) or the like can be used in the same manner as the magnetic field detecting element.

  Further, as described above, the second measurement rotating body 20 has five notches 20a to 20e that engage with the feed pin 11 of the first measurement rotating body 10 in the circumferential direction constituted by the Geneva gear. Is formed.

  The second measuring rotator 20 uses a Geneva gear having the above-mentioned magnet at the center, and four Hall elements are arranged on a case around the Geneva gear.

  As a result, a permanent magnet 25 that generates a magnetic field in the radial direction of the rotating body and changes the strength of the magnetic field in the circumferential direction of the rotating body at the center of the second measuring rotating body 20 is provided on the substrate. The output signals of the four hall elements 36 to 39 arranged are processed by a microcomputer (not shown), and the first measuring rotating body 10, that is, the object to be measured is determined from the rotation angle of the second measuring rotating body 20. The number of rotations of the rotating body 50 is detected.

  Specifically, as shown in the lower part of FIG. 4, the output of the Hall elements 36 to 39 changes stepwise by intermittently sending the second measurement rotating body 20. It is possible to detect whether the main rotator 50 belongs to any rotation number from the first rotation to the fifth rotation among −900 ° to + 900 ° by the step change of the output.

  It should be noted that, in detecting the number of rotations of the rotating body to be measured 50 by the second measuring rotating body 20 and the Hall elements 36 to 39, the two measuring elements other than the 180 ° opposing positions are used as the second measuring rotating body. In order to ensure detection accuracy by using these differential signals at predetermined positions in the circumferential direction, the rotational speed of the first measuring rotating body 10 is suppressed by minimizing fluctuations due to the DC level and temperature of the stepwise signal. That is, it is also possible to calculate the rotation speed of the rotating body 50 to be measured.

  Accordingly, when notches for intermittent feeding are formed at predetermined intervals around the entire circumference in the periphery of the second measurement rotating body 20, at least two Hall elements are arranged at predetermined intervals in the circumferential direction. There is no need to arrange the four Hall elements in the circumferential direction as in this embodiment.

  Next, a method for detecting the absolute rotation angle of the rotating body to be measured 50 by the rotation sensor 1 having the above configuration will be described. FIG. 3 is a flowchart for calculating the absolute rotation angle of the rotating body to be measured 50 in the above-described embodiment.

  As shown in FIG. 1, the rotation sensor of the present embodiment constitutes a rotating body for measurement 50 because a rotor having a primary gear is directly fitted into a rotating shaft S as a main rotating body 50. The gear can be completely synchronized with the rotation of the shaft S.

  In obtaining the absolute rotation angle of the main rotating body that is the rotating body 50 to be measured, first, the magnet 15 and the Hall element 31 provided in the first measuring rotating body 10 that rotates at the same rotational speed as the main rotating body 50. From 34, the rotation angle of the main rotating body 50 in the small angle range of 0 ° to + 360 ° is detected.

  Many methods for calculating a 360 ° absolute angle signal shown in the upper part of FIG. 4 from four sine wave signals having a period of 360 ° and having a phase difference of 90 ° are already in practical use.

  In the present embodiment, Hall elements 31 to 34, which are one form for carrying out this method, are arranged on the substrate 40 at equal intervals at an angle of 90 ° in the circumferential direction of the first measurement rotating body 10. Therefore, four sine wave signals having a phase difference of 90 ° are obtained by the rotation of the first measurement rotating body 10.

  Then, while using the positive rising portions of the four sine wave signals having a phase difference of 90 ° from each other, the magnitude relation of each sine wave signal is compared, and the upper portion of FIG. A rotation angle detection output of 0 ° to + 360 ° on a straight line as shown is obtained. Then, a small angle is calculated from 0 ° to + 360 ° of the rotating body to be measured (step S1).

  Note that at this stage, it is not possible to grasp how many rotations the main rotor 50 is in the range of −900 ° to + 900 °. Therefore, it is detected how many rotations of the main rotating body 50 are using the second measuring rotating body 20 formed of a Geneva gear and the Hall elements 36 to 39.

  Note that the stepped signals in the lower stage of FIG. 4 are arranged to face each other, for example, at an angle of 180 ° in the circumferential direction among the Hall elements 36 to 39 accompanying the intermittent rotation of the second measuring rotating body 20 formed of a Geneva gear. An output signal obtained from a combination of two Hall elements that is not shown. The output signal shown in the lower part of FIG. 4 is shown as a voltage, and shows a waveform that changes in units of 1 V between 0.5 V and 4.5 V. However, other waveforms may be used.

  By using this stepwise signal, the first measurement rotator 10, that is, the main rotator 50, has an absolute rotation angle of −900 ° to + 900 ° from the second measurement rotator 20 and the Hall elements 36 to 39. The number of rotations belonging to the specified 1 to 5 rotations is detected.

  Specifically, in detecting the number of rotations of the main rotating body 50, in the case of the present embodiment, the second measuring rotation formed by a Geneva gear that intermittently rotates the rotation of the first measuring rotating body 10. The rotation angle of the body 20 is measured from a combination of a required number of Hall elements among the four Hall elements 36 to 39 in the same manner as the first measurement rotating body 10.

  That is, in the case of the present embodiment, the permanent magnet 25 having a radial magnetic field is rotated, and a necessary number of combinations of the four Hall elements 36 to 39 arranged at intervals of 90 ° around the permanent magnet 25 are output. It outputs four step signals with a 360 ° period.

  Then, by using the Hall elements 36 to 39 accompanying the rotation of the second measuring rotating body 20 that is decelerated from the first measuring rotating body 10, out of the angular range of −900 ° to + 900 °, Whether the main rotating body belongs to any one of the first to fifth rotations, that is, the number of rotations of the main rotating body 50 is calculated in five stages (step S2).

  Then, by combining the rotation number signal of the main rotor 50 and the detection result of the small angle signal of 0 ° to + 360 ° of the main rotor 50 that has already been calculated, the main rotor 50 is −900 ° to + 900 °. Among these, it is determined whether the rotation speed is from the first rotation to the fifth rotation and the small rotation angle of 0 ° to 360 ° at the rotation speed. Thereby, the absolute rotation angle of the rotating body 50 to be measured can be calculated (step S3).

  Two to four Hall elements 31 to 34 and 36 to 39 are arranged for the same speed gear as the first measurement rotating body 10 and the Geneva gear as the second measurement rotating body 20. In the case of two or four, it is desirable to arrange them at an angle of 90 ° in the circumferential direction.

  For example, when only two Hall elements are arranged at an angle of 90 ° in the circumferential direction, a total of four sine wave signals are obtained by inverting the output of the sine wave signal of each Hall element. From the combination of signal outputs, the main rotation is determined from the small output of 0 ° to 360 ° of the first measuring rotator 10 and the Hall elements 31 to 34 and the output of the second measuring rotator 20 and the Hall elements 36 to 39. It can be determined which of the first to fifth rotations of the body 50 is present.

  As described above, by using the rotation sensor according to the present invention, it is not necessary to take a method of detecting the rotation speed by the phase difference between the three rotating bodies as in the conventional rotation sensor, and the backlash of the gear is eliminated. As a result, the detection accuracy can be improved.

  In the above-described embodiment, four Hall elements are arranged in the Geneva gear. For example, a sufficient number of Geneva gears to detect the number of rotations of the first rotating body within 180 ° in the circumferential direction of the Geneva gear. If the notch portions for intermittent feeding are formed at predetermined intervals in the circumferential direction, the rotation of the first measuring rotating body can be performed by detecting the rotation angle within 180 degrees of the Geneva gear by arranging only one Hall element. It is also possible to detect the number.

  Further, as in this embodiment, a sufficient number of Geneva gear intermittent feed notches for detecting the rotational speed of the first measuring rotor in the circumferential direction of the Geneva gear are formed at predetermined intervals in the circumferential direction. If it is, the rotation angle of 360 degrees of the Geneva gear can be detected only by arranging two Hall elements other than the mutually opposing positions forming the circumferential direction of 180 degrees. It becomes possible to detect the number of rotations of the body. In this case, a magnetoresistive element (MR element) or the like can be used in the same manner as the magnetic field detecting element.

  The rotation sensor according to the present invention is particularly suitable for detecting the rotation angle of a vehicle steering apparatus that is quite susceptible to vibration. However, the rotation sensor according to the present invention can be applied to any sensor as long as it obtains the relative rotation angle and rotation torque between rotating shafts that rotate while vibrating, such as a robot arm.

It is the top view which showed roughly the internal structure of the rotation sensor concerning one Embodiment of this invention. It is the figure which showed the schematic block diagram in embodiment of this invention. It is the figure which showed the flowchart for absolute rotation angle calculation in embodiment of this invention. It is a figure explaining the detection method of the absolute rotation angle of the main rotary body of the rotation sensor shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rotation sensor 10 1st measurement rotary body 11 Feed pin 15 Permanent magnet 20 2nd measurement rotary body 20a-20e Notch 25 Permanent magnet 30 Case 31-34, 36-39 Magnetic field detection element 40 Substrate 50 Covered Rotating body for measurement (main rotating body)
S shaft

Claims (3)

In the rotation sensor that measures the rotation angle of the rotating body to be measured using a measuring rotating body other than the rotating body to be measured,
A first measurement rotating body that rotates at approximately the same rotational speed as the measurement rotating body in conjunction with the measurement rotating body, and a rotation that rotates in conjunction with the first measurement rotating body. A second measuring rotator whose number is smaller than the first measuring rotator,
The rotating body for measurement and the first rotating body for measurement are connected by a gear,
The first measuring rotating body and the second measuring rotating body are connected by a gear, and the second measuring rotating body rotates intermittently with the rotation of the first measuring rotating body. ,
A permanent magnet having a radial magnetic field is arranged at the center of each of the first measuring rotating body and the second measuring rotating body, and further, a change in the radial direction of the magnetic field generated by each permanent magnet can be detected. A predetermined number of magnetic field detection elements are respectively arranged at different positions independently of the rotation of the first and second rotating bodies for measurement,
By measuring the rotation angle of the first measurement rotating body and the rotation number of the second measurement rotating body using the output of the magnetic field detection element, the absolute rotation angle of the rotating body to be measured is measured. A rotation sensor.   The rotation sensor according to claim 1, wherein the magnetic detection element is a Hall element.   The rotation sensor according to claim 1, wherein the magnetic detection element is a magnetoresistive element.

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