JP2006292529A - Device for measuring rotational angle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device for measuring rotational angle capable of improving measurement accuracy and miniaturization. <P>SOLUTION: A spiral groove 3 is formed on the surface 1a of the turning disk 1, and the two turning arms 5 and 6 are extended to the surface of the disk 1 from the rotational axis 4 outside of the disk 1. One turning arm 5 is separated from the line connecting the rotational axis 2 and the rotational axis 4 to the clockwise turning side, and the other turning arm 6 is separated from the line connecting the turning axis 2 and the rotational axis 4 to the counter clockwise turning side, on each rotation arm 5 and 6 a head 7 or 8 is formed and guided by the spiral groove 3, respectively. The angle difference sensor 9 for detecting the difference in the rotational angles of both the turning arms 5 and 6 is provided; and from the difference of turning angles, the turned angle of the disk 1 is obtained. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a rotation angle measurement apparatus suitable for a measurement object that rotates multiple times, and more particularly to a rotation angle measurement apparatus that improves measurement accuracy and can be miniaturized.

  An angle (referred to as an absolute rotation angle) that distinguishes a rotation angle of a rotating body that rotates 360 ° or more (also referred to as multiple rotations or multiple rotations) from a rotation angle of 360 ° or less, as in the detection of an absolute steering angle in a steering wheel of a vehicle. In order to perform measurement, it is necessary to introduce an element that does not return with a period of 360 °.

  The technique of Patent Document 1 will be described with reference to FIG. 5. A main gear 51 whose absolute rotation angle is to be measured, and two auxiliary gears (first auxiliary gear and second auxiliary gear) 52 and 53 meshing with the main gear. The angle sensors 54 and 55 for detecting the rotation angles of the auxiliary gears 52 and 53 and the evaluation circuit 56 for obtaining the absolute rotation angle based on the outputs of the angle sensors 54 and 55 are provided. The number of teeth of the first auxiliary gear 52 and the number of teeth of the second auxiliary gear 53 are less than the number of teeth of the main gear 51 and are different from each other. The main gear 51 is fixed to a steering shaft that rotates integrally with the steering wheel.

  When the steering shaft rotates, the main gear 51 fixed to the steering shaft rotates, and the auxiliary gears 52 and 53 also rotate in proportion to the rotation angle of the main gear 51. As a result, each angle sensor 54, 55 outputs a signal proportional to the rotation angle of the auxiliary gears 52, 53. The relationship between the rotation angle of the main gear 51 and the output signals of the angle sensors 54 and 55 is shown in FIG.

  As shown in the figure, since the number of teeth of the two auxiliary gears 52 and 53 is different, the output signals C and D of the angle sensors 54 and 55 change at different periods, and the difference between the two output signals C and D is the rotation angle. It depends on. The evaluation circuit 56 calculates an absolute rotation angle based on the difference between the two output signals C and D.

  7A and 7B, the distance from the rotating shaft 72 gradually increases (or gradually decreases) while rotating around the rotating shaft 72 on the surface 71a of the rotating disc 71. FIG. ), A rotating arm 75 is extended from the rotating shaft 74 outside the disk 71 onto the surface 71a of the disk 71, and a head 77 guided by the rotating groove 75 is guided to the rotating arm 75. And an angle difference detection sensor (not shown) for detecting the rotation angle of the rotation arm 75 is provided, and the rotation angle of the disk 71 is obtained from the rotation angle. The disc 71 is fixed to a steering shaft that rotates integrally with the steering wheel. As the angle difference detection sensor, for example, a magnet is attached to the rotation arm 75, and a magnetic detection element that generates a signal by the Hall effect or the magnetoresistance effect is installed at a place where the rotation is not performed.

  Now, when one end of the spiral groove 73 is in the vicinity of the outermost periphery of the surface 71a of the disk 71, and the spiral groove 73 is formed so that the distance from the rotating shaft 72 is shortened when proceeding counterclockwise from this point, The opposite end of the spiral groove 73 reaches the innermost circumference of the surface 71 a of the disk 71. In other words, even if the spiral groove 73 is formed so that the distance from the rotating shaft 72 becomes longer as it goes clockwise starting from the innermost periphery, the same result can be obtained.

  When the steering shaft rotates, the disk 71 fixed to the steering shaft rotates. Since the head 77 is guided by the spiral groove 73, when the disk 71 rotates clockwise, the head 77 moves relatively counterclockwise with respect to the disk 71. When the lens rotates counterclockwise, it moves relative to the disk 71 in a clockwise direction, and therefore moves away from the rotating shaft 72. By the movement of the head 77, the rotating arm 75 rotates around the rotating shaft 74. The absolute rotation angle is calculated by an arithmetic circuit (not shown) based on the rotation angle signal output from the angle difference detection sensor.

  As shown in FIG. 8, the output signal of the angle difference detection sensor is linear from a region where the absolute rotation angle is negative (for example, −1080 °) to a region where the absolute rotation angle is positive (for example, 1080 °). To increase. The angle of the pivot arm when the absolute rotation angle is 0 ° is around the middle of the pivot range shown in FIG.

JP-T-2002-53858 Japanese Patent Laid-Open No. 10-38557 JP 2004-125440 A

  Since the rotation angle measuring device used for detecting the steering angle is provided in the cockpit, it is necessary to reduce the size from the viewpoint of driver operability and comfort. However, since the rotation angle measuring device of FIG. 5 calculates the absolute rotation angle using the fact that the rotation angles of the two auxiliary gears 52 and 53 change at different periods, the teeth of both the auxiliary gears 52 and 53 are calculated. There is a limit to the range of rotation angles that can be detected with the least common multiple of the number. In order to widen this rotation angle range, if the difference in the number of teeth of each sub gear 52, 53 with respect to the number of teeth of the main gear 51 is reduced and the number of teeth is increased, the diameter of the sub gears 52, 53 increases and the rotation angle is measured. The device becomes large.

  In the rotation angle measuring device of FIG. 7, since the rotation angle of the rotation arm 75 is smaller than the rotation angle of the disk 71, the influence of noise on the rotation angle signal output from the angle difference detection sensor. Therefore, the rotational angle measurement accuracy is low.

  Therefore, an object of the present invention is to provide a rotation angle measuring device that solves the above-described problems, improves the measurement accuracy, and can be miniaturized.

  In order to achieve the above object, the present invention forms a spiral groove on the surface of a rotating disk, extends two rotating arms from the rotating shaft outside the disk onto the surface of the disk, and one rotating arm. Is distributed clockwise on the line connecting the rotating shaft and the rotating shaft, and the other rotating arm is distributed counterclockwise on the line connecting the rotating shaft and the rotating shaft. A head guided by the spiral groove is formed, an angle difference detection sensor for detecting a difference in rotation angle between the two rotation arms is provided, and a rotation angle of the disk is obtained from the difference in rotation angle. It is.

  The spiral groove may be formed by making a plurality of turns around the rotation axis.

  The angle difference detection sensor may be composed of a magnet that rotates in association with one rotation arm and a magnetic detection element that rotates in association with the other rotation arm.

  A tooth is formed on the outer periphery of the disk, the disk is used as a main gear, a sub gear is meshed with the main gear, and a sub gear rotation angle sensor for detecting the rotation angle of the sub gear is provided. A precise rotation angle of the disk may be obtained using a rotation angle of the disk obtained from a difference in rotation angle between the two rotation arms.

  The present invention exhibits the following excellent effects.

  (1) Measurement accuracy can be improved.

  (2) The size can be reduced.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

  As shown in FIG. 1A to FIG. 1C, the rotation angle measuring device according to the present invention is a distance from the rotating shaft 2 while rotating around the rotating shaft 2 around the surface 1a of the rotating disk 1. Is formed in a spiral groove 3 that gradually increases (or gradually decreases), the two rotating arms 5 and 6 extend from the rotating shaft 4 outside the disk 1 onto the surface 1a of the disk 1, and one rotating arm 5 has a rotating shaft. 2 and the other rotating arm 6 are distributed on the counterclockwise side of the line connecting the rotating shaft 2 and the rotating shaft 4 to the respective rotating arms 5 and 6. Is formed with heads 7 and 8 guided by the spiral groove 3, and is provided with an angle difference detection sensor 9 for detecting a difference in rotation angle between the two rotation arms 5 and 6. The rotation angle is obtained.

  The spiral groove 3 may be formed by making a plurality of turns around the rotation shaft 2. The illustrated spiral groove 3 is formed so that one end is near the outermost periphery of the surface 1a of the disk 1 and the distance from the rotating shaft 2 is shortened as it proceeds clockwise from this point. The opposite end reaches the innermost circumference of the surface 1 a of the disk 1. In other words, even if the spiral groove 3 is formed so that the distance from the rotating shaft 2 becomes longer as it goes counterclockwise starting from the innermost circumference, the same result can be obtained. Of course, the principle is the same even if the direction of the vortex is reversed as in FIG.

  For example, the spiral groove 3 is a groove having a U-shaped cross section. The heads 7 and 8 are restricted from moving in the pitch direction of the groove (the radial direction of the disk 1) by fitting a round bar at the tip into the recess of the spiral groove 3. When the disk 1 is rotated almost once, the heads 7 and 8 are moved by one pitch.

  The angle difference detection sensor 9 may be anything as long as it can detect the rotation angle difference between the two rotation arms 5, 6, but here, the magnet 10 that rotates accompanying the one rotation arm 5 and The angle of the magnetic detection element 11 with respect to the magnet 10 is changed by comprising a magnetic detection element (for example, Hall element) 11 that rotates accompanying the other rotation arm 6.

  The arithmetic circuit 12 connected to the angle difference detection sensor 9 obtains the rotation angle of the disk 1 from the rotation angle difference detected by the magnetic detection element 11.

  As an application to steering angle detection, in the rotation angle measuring device of FIG. 1, the disk 1 is attached to the steering shaft, and the rotating shaft 4 is fixed in the vehicle interior.

  The operation of the rotation angle measuring device of FIG. 1 will be described.

  When the steering shaft rotates, the disk 1 fixed to the steering shaft rotates. Since the heads 7 and 8 are guided by the spiral groove 3, when the disk 1 rotates clockwise, the heads 7 and 8 move relative to the disk 1 counterclockwise. When the disk 1 rotates counterclockwise, the disk 1 moves relative to the disk 1 in the clockwise direction, and thus approaches the rotating shaft 2.

  Since the rotation arm 5 faces the clockwise side of the line connecting the rotation shaft 2 and the rotation shaft 4, the rotation arm 5 moves around the rotation shaft 4 by the movement of the head 7 away from the rotation shaft 2. Rotate clockwise. On the other hand, the rotating arm 6 faces the counterclockwise direction of the line connecting the rotating shaft 2 and the rotating shaft 4, so that the moving arm 6 moves away from the rotating shaft 2, so that the rotating arm 6 moves to the rotating shaft 4. Rotate clockwise around. That is, the two rotating arms 5 and 6 rotate in opposite directions. For this reason, the rotation angle difference between the two rotation arms 5 and 6 depending on the rotation of the disk 1 changes significantly more than the rotation angle of the single rotation arm.

  The arithmetic circuit 12 obtains the rotation angle of the disk 1 from the rotation angle difference detected by the angle difference detection sensor 9. At this time, the relationship between the rotation angle of the disk 1 and the rotation angle difference between the rotation arms 5 and 6 is as shown by the solid line in FIG. If the magnitude of the signal output by the angle difference detection sensor 9 is taken on the right vertical axis, this solid line is a graph of the rotation angle versus signal magnitude. In FIG. 2, when the absolute rotation angle is −1080 °, the rotation angle difference is 0 °. In this example, the two rotating arms 5 and 6 are distributed symmetrically with respect to a line connecting the rotating shaft 2 and the rotating shaft 4. As shown in the figure, the rotation angle difference detected by the angle difference detection sensor 9 is θ when the absolute rotation angle is 0 °, and 2θ when the absolute rotation angle is 1080 °. The rotation angle of the single rotation arm indicated by the alternate long and short dash line is only θ when the absolute rotation angle is 1080 °. That is, in this embodiment, a signal having a value twice as large as that of the conventional rotation angle can be obtained.

  As described above, the present invention obtains the absolute rotation angle from the rotation angle difference between the rotation arms 5 and 6, so that the influence of noise on the output signal of the angle difference detection sensor 9 is reduced. As a result, the rotation angle measurement accuracy is improved.

  Further, although the number of rotating arms is increased by one compared with the rotating angle measuring apparatus of FIG. 7 having one rotating arm, an extra protrusion does not increase, so that the rotating angle measuring apparatus can be enlarged. As compared with the rotation angle measuring device shown in FIG.

  Next, another embodiment will be described.

  The rotation angle measuring apparatus shown in FIG. 3 has teeth on the outer periphery 1b of the disk 1 shown in FIG. 1 as the main gear 1 'in addition to the structure shown in FIG. Is provided, and a sub-gear rotation angle sensor 32 for detecting the rotation angle of the sub-gear 31 is provided, and the arithmetic circuit 12 'calculates the rotation angle difference between the sub-gear rotation angle and the two rotation arms 5 and 6 described above. The precise rotation angle of the disk 1 is obtained using the obtained rotation angle of the disk 1.

  The number of teeth of the auxiliary gear 31 is smaller than the number of teeth of the main gear 1 '. As the auxiliary gear rotation angle sensor 32, for example, a magnet 33 is attached to the auxiliary gear 31, and a magnetic detection element 34 that generates a signal by a Hall effect or a magnetoresistive effect is installed at a place where it does not rotate.

  The operation of the rotation angle measuring device of FIG. 3 will be described.

  The change of the rotation angle difference with respect to the rotation angle of the disk 1 is as described above. As shown in FIG. 4, the output signal A of the angle difference detection sensor 9 continues to increase linearly with the increase of the rotation angle. . On the other hand, the output signal B of the auxiliary gear rotation angle sensor 32 has a sawtooth waveform that repeats linear increase and reset of the increase depending on the rotation angle. Since the number of teeth of the sub-gear 31 is smaller than the number of teeth of the main gear 1 ′, the output signal B has a cycle shorter than 360 °.

  Comparing the rotation angles or rotation angles of the various members when the disk 1 rotates with the steering shaft, the rotation angle of the auxiliary gear 31 is larger than the rotation angles of the rotation arms 5 and 6. Therefore, the rotation angle of the auxiliary gear 31 more accurately represents the rotation angle of the disk 1 than the rotation angle of the rotation arms 5 and 6. Therefore, the auxiliary gear 31 is used to assist in increasing the measurement accuracy of the rotational angle of the disk 1 obtained from the rotational angle of the rotational arms 5 and 6.

  Therefore, the arithmetic circuit 12 ′ obtains a precise rotation angle of the disk 1 using the auxiliary gear rotation angle indicated by the output signal B and the rotation angle of the disk 1 indicated by the output signal A of the angle difference detection sensor 9. Specifically, the value of the output signal A and the value of the output signal B are measured while measuring the rotation angle of the rotating disk 1 or the rotating shaft 2 using a precision measuring instrument capable of measuring a precise rotation angle in advance. By reading, the value of the output signal A, the value of the output signal B, and the precise rotation angle are correlated and stored in the memory, and then the rotation angle is measured by the rotation angle measuring device of the present invention. The precise rotation angle is read out from the memory using the detected value of the output signal A and the value of the output signal B.

  According to this embodiment, the auxiliary gear rotation angle sensor 32 can detect the rotation angle with higher sensitivity than the angle difference detection sensor 9, and thus can measure the rotation angle with higher accuracy. Further, since the number of gears is smaller than that of the conventional configuration, the size can be reduced.

It is a block diagram of the rotation angle measuring device which shows one Embodiment of this invention, (a) is a perspective view, (b) is a sectional side view, (c) is a top view. It is a rotation angle vs. rotation angle difference characteristic view in the rotation angle measuring device of FIG. It is a lineblock diagram (perspective view) of a rotation angle measuring device showing one embodiment of the present invention. It is a rotation angle vs. rotation angle difference in the rotation angle measuring apparatus of FIG. 3, and an auxiliary gear rotation angle sensor output characteristic view. It is a block diagram of the conventional rotation angle measuring apparatus. FIG. 6 is a rotation angle versus output characteristic diagram of each angle sensor in the rotation angle measurement device of FIG. 5. It is a block diagram of the conventional rotation angle measuring apparatus. FIG. 8 is a rotation angle versus rotation angle characteristic diagram in the rotation angle measurement device of FIG. 7.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Disc 1a (Disk) surface 2 Rotating shaft 3 Spiral groove 4 Rotating shaft 5, 6 Rotating arm 7, 8 Head 9 Angle difference detection sensor

Claims (4)

  A spiral groove is formed on the surface of the rotating disk, two rotating arms are extended from the rotating shaft outside the disk to the surface of the disk, and one rotating arm connects the rotating shaft and the rotating shaft. On the clockwise side of the line, the other rotating arm is distributed to the counterclockwise side of the line connecting the rotating shaft and the rotating shaft, and a head guided by the spiral groove is formed on each rotating arm. A rotation angle measuring device provided with an angle difference detection sensor for detecting a rotation angle difference between the two rotation arms, and obtaining a rotation angle of the disk from the rotation angle difference.   2. The rotation angle measuring device according to claim 1, wherein the spiral groove is formed by making a plurality of rounds around the rotation axis.   The said angle difference detection sensor is comprised from the magnet which rotates accompanying the one rotation arm, and the magnetic detection element rotated accompanying the other rotation arm, or characterized by the above-mentioned. The rotation angle measuring device according to 2. A tooth is formed on the outer periphery of the disk, the disk is used as a main gear, a sub gear is meshed with the main gear, and a sub gear rotation angle sensor for detecting the rotation angle of the sub gear is provided. The rotation according to any one of claims 1 to 3, wherein a precise rotation angle of the disk is obtained using a rotation angle of the disk obtained from a rotation angle difference between the two rotation arms. Angle measuring device.

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