JP2006090982A - Rotation angle detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily and precisely measure a rotation angle, in particular its absolute angle of a rotating body, by using a compact mechanism. <P>SOLUTION: A rotation angle detector is provided, which comprises; the rotating body 2 with a first tooth 2a, on the upper surface of which a spiral groove section 2b is formed; a moving body 4 which moves along the groove section 2b of the rotating body; a rotating body angle sensor 6 which detects a movement angle of the moving body 4 when the rotating body 2 rotates; a gearwheel 7 which has a second tooth 7a engaging with the first tooth 2a of the moving body 4 and rotates along with the rotating body 2; a gearwheel angle sensor 8 which detects a rotation angle of the gearwheel 7; and an arithmetic section 9 which detects a rotation angle of the rotating body 2, on the basis of both output signals of the rotating body angle sensor 6 and the gearwheel angle sensor 8. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a rotation angle detection device that can detect a rotation angle of a rotating body, in particular, an absolute angle of 360 degrees or more, easily and with high accuracy by a compact mechanism.

  Since the steering of a vehicle such as an automobile is directly connected to the straightness and directionality of the vehicle, a rotation angle detection system that operates by being directly connected to the steering is extremely important for improving the performance of the vehicle and ensuring the safety of the driver. For this reason, various rotation angle detection devices have been proposed as follows.

For example, a rotation angle detection device (hereinafter referred to as “technical example 1”) that detects a rotation angle from the angles of two rotating bodies (gears) that are composed of at least a plurality of pairs and have a phase difference has been proposed (see Patent Document 1). ).
FIG. 6 is a perspective view of the embodiment. The rotation angle detection device 10 includes a rotating body 11 having driving teeth 11a on the outer periphery, at least two gears 12 and 13 having teeth 12a and 13a meshing with the rotating body 11 (in the case of one pair), and gears 12 and 13 The angle sensors 14 and 15 that detect the rotation angle and the evaluation circuit (not shown) that converts the outputs of the angle sensors 14 and 15 into absolute angles are configured. The number of teeth of the gears 12 and 13 meshing with the rotating body 11 is less than the number of teeth of the rotating body 11, and the number of teeth of the two gears 12 and 13 are different from each other. In the case of detecting the absolute steering angle of the steering wheel, the rotating body 11 is fixed to the steering shaft (not shown). When the steering shaft rotates, the rotating body 11 fixed to the steering shaft rotates. When the rotating body 11 rotates, the two gears 12 and 13 rotate, and signals proportional to the rotation angle are output from the angle sensors 14 and 15 of the gears 12 and 13. The feature of this technical example 1 is that the accuracy of the absolute angle is increased by using a plurality of a pair of pair gears having different numbers of teeth and correcting an output error occurring between the pair gears in an evaluation circuit.

Next, in connection with the improvement of the first technical example, a rotation angle detecting device used for detecting the rotation angle of a steering wheel of an automobile, etc., which has a small detection error and facilitates calculation processing of a detection circuit. (Hereinafter referred to as Technical Example 2) has been proposed (see Patent Document 2).
FIG. 7 is a perspective view of a main part of the rotation angle detection device 20 of the embodiment. A rotating body 21 having a drive gear 21a formed on the outer periphery, a detection gear 22 meshing with the drive gear 21a, and a helical screw 23a threaded on the shaft portion 23 of the detection gear 22 as the detection gear 22 rotates. And a detecting means 25 for detecting the movement of the moving body 24. The detecting means 25 outputs a detection signal for gradually increasing or decreasing the movement of the moving body 24, and the rotating body 21 It is characterized in that the rotation angle of the can be detected. The advantage of the second technical example is that the rotation angle detector 10 can be reduced in size and thickness.

Furthermore, the mechanism is different from those of the technical examples 1 and 2 in which the rotation angle is detected by the output signal from the gear, and the rotation amount from the reference position at the reference rotation speed is ensured by the combination mechanism of the rotating body 31 and the arm 32. A rotation sensor to be detected (hereinafter referred to as technical example 3) has been proposed (see Patent Document 3).
FIG. 8 is a plan view of the rotating body 31 showing an engagement state of the rotation sensor 30 with the arm 32. The tip 32a of the arm 32 can be reciprocated to the inner and outer peripheries of the groove 31b along the spiral groove 31b provided on the surface of the rotator 31 by the pickup method. ) Is the neutral position of the steering wheel, and at this position, the window portion S provided in the shutter portion 32b which is the other end of the arm 32 and the reference slit T provided at a predetermined position of the rotating body 31 are made to coincide with each other. The number of rotations of the rotating body 31 is detected as 1 based on the signal. The feature of this technical example 3 is that the backlash between the gears due to backlash or the like can be eliminated because no gear is used for transmission of rotation.
JP-T-2002-53858 JP 2002-206910 A Japanese Utility Model Publication No. 5-23037

  However, in the rotation angle detection device 10 of the technical example 1, the detection of the rotation angle of the rotating body 11 is performed by two gears 12 and 13 including a first detection gear 12 and a second detection gear 13 that mesh with the rotating body 11. Therefore, when the rotation operation starts or reverse rotation, rattling occurs due to the gap between the drive gear 11a of the rotating body 11 and the first detection gear 12 and the second detection gear 13 (backward). An error is likely to occur in angle detection due to the occurrence of rush. In particular, this error may increase as the number of paired gears increases. Further, when the range of the rotation angle to be detected is increased, it is necessary to increase the number of teeth of each gear from the periodic relationship between the rotating body 11 and the two detection gears, and the overall apparatus can be reduced in size. There are also challenges that become difficult.

  In the rotation angle detection device 20 of the technical example 2, a voltage is output in proportion to the rotation angle. However, the detection circuit also has a detection limit, and the detection accuracy decreases as the rotation angle detected increases. Therefore, it becomes difficult to maintain high-precision detection over the entire area. In this case, if the detection limit is reduced and the performance is improved, there arises a problem that the manufacturing cost of the device itself becomes expensive. In addition, as the rotation angle that can be detected increases, the moving distance of the moving body 24 becomes longer, which makes it difficult to reduce the size of the apparatus.

  In addition, since the rotation sensor 30 of the technical example 3 is not equipped with a gear, it is possible to eliminate the occurrence of an angle detection error due to rattling or the like generated between the gears as in the technical example 1 and the technical example 2. However, simultaneously adjusting the neutral position of the steering wheel, the window portion of the arm, and the reference slit requires accuracy in terms of mechanism, and precision machining is required. Therefore, it is not suitable for mass production, and the manufacturing cost of the apparatus increases. Further, in the technical example 3, when the tip 32a of the arm 32 comes to the neutral position of the rotating body 31, the window 31 S of the arm 32 and the reference slit T coincide with each other to reset the rotating body 31 as one rotation. Therefore, the purpose of providing the spiral groove 31b in the rotating body 31 is not provided for the purpose of directly detecting the rotation angle of the rotating body 31 (the detection of the rotation angle is not performed). The detecting means detects a large number of counting slits 31a provided in the vicinity of the outer periphery of the outer periphery.

  Therefore, the present invention solves the problems of these technical examples and makes it possible to easily and highly accurately detect the rotation angle of the rotating body, in particular, the absolute angle thereof by a compact mechanism. The purpose is to provide.

  In order to achieve the above object, the present invention provides a rotating body having first teeth and having a spiral groove formed on the upper surface, a moving body that moves along the groove of the rotating body, A rotating body angle sensor that detects a moving angle of the moving body when the rotating body rotates, and a second tooth that meshes with the first tooth of the rotating body, and rotates as the rotating body rotates. And a gear angle sensor for detecting the rotation angle of the gear, and an arithmetic unit for detecting the rotation angle of the rotating body based on both output signals of the angle sensor for the rotating body and the angle sensor for the gear. It is characterized by that. Therefore, it is possible to detect the rotation angle (absolute angle) of the rotating body with high accuracy based on both output signals of the rotating body angle sensor and the gear angle sensor.

In this case, it is preferable that the number of teeth of the second tooth of the gear is smaller than the number of teeth of the first tooth of the rotating body. The smaller the number of gear teeth relative to the number of teeth of the rotating body, the smaller the waveform pitch of the output signal of the gear angle sensor. Therefore, the rotational angle of the rotating body with high resolution in relation to the angle sensor for rotating bodies (Absolute angle) can be detected.

  Moreover, it is preferable that the angle sensor for rotating bodies and the angle sensor for gears perform angle detection by a Hall element or a magnetoresistive element. This is because an angle sensor using these effects can detect even a magnet that does not move when the rotating body is in a stopped state of a gear (using a Hall element) and can easily detect the direction of rotation (using a magnetoresistive element).

  Moreover, it is preferable that the said moving body is a head which is attached to the end of the arm which rotates circularly centering on a fulcrum, and is located in the said groove | channel. The head can reliably trace the spiral groove by the pickup method.

  The moving body is a head movably attached to a fixed arm orthogonal to the groove, and the rotating body angle sensor is a rotating body position sensor that detects a moving position of the moving body. It is preferable. The head can be traced more reliably with a linear tracking system without overhanging the spiral groove.

  According to the rotation angle detection device of the present invention, the rotation angle is detected by the arm that moves the groove portion of the rotating body, and the angle detection for each rotation number is detected and shared by the gears, and the signal that is simultaneously generated. By reading and analyzing the relationship between the output waveforms, the rotation angle (absolute angle) of the rotating body can be detected with high accuracy. Also, since there is only one gear that transmits rotation to the rotating body in terms of the mechanism, it has a very simple structure and can be downsized as a whole device.

  Next, the best mode for carrying out the present invention will be described with reference to FIGS. FIG. 1 is a perspective view of a main part of an embodiment of the rotation angle detecting device of the present invention, FIG. 2 is a plan view thereof, and FIG. 3 is a sectional view of a moving body in a groove of a rotating body.

  The rotation angle detection device 1 is a magnetoresistive sensor comprising a rotating body 2, a moving body 4, an arm 5, and a gear 7 as main mechanisms, and an angle sensor 6 for the rotating body, a magnet 8a mounted on the gear 5, and a semiconductor MR element 8b. An arithmetic unit 9 that electrically converts output signals from the gear angle sensor 8, the rotating body angle sensor 6, and the gear angle sensor 8 into a waveform is configured as an electrical system.

  The rotating body 2 has a central through-hole inserted into and fixed to the steering shaft 3 and rotates clockwise and counterclockwise as the steering shaft 3 rotates. In general, the steering shaft 3 is cut to the left and right to lock and lock when the steering wheel is rotated 3 to 6 clockwise and counterclockwise. Rotate with.

On one disk surface (the upper surface in FIG. 1) of the rotating body 2, a spiral groove 2b is formed from the outer periphery toward the center. Since this groove portion 2b is sufficient as long as the number of rotations of the rotary body 2 is sufficient, the number of rotations is two.

  First teeth 2 a are engraved on the outer periphery of the rotating body 2.

  The moving body 4 includes a rotating body angle sensor 6 whose position is fixed, a rotatable arm 5 supported by the rotating body angle sensor 6, and a head 4 serving as a moving body mounted on the tip of the arm 5. It is configured. The head 4 traces the groove 2b of the rotating body 2 (see FIG. 3) so that the arm 5 moves while drawing a curved locus between the inner and outer circumferences of the groove 2b following the rotation of the rotating body 2. It has become. The number of circular spirals of the groove portion 2b is set to six.

  The gear 7 has second teeth 7 a, and the second teeth 7 a mesh with the first teeth 2 a of the rotating body 2. Since the number of teeth of the second tooth 7 a is smaller than the number of teeth of the first tooth 2 a, the rotation speed of the gear 7 is larger than that of the rotating body 2. The gear 7 is equipped with a magnet 8 a that is one of the gear angle sensors 8. The magnet 8 a is mounted substantially at the center of the gear 7 and rotates with the rotation of the gear 7. A magnetism detecting element (for example, MR element) 8b for detecting a change in magnetic force of the magnet 8a is fixed to the magnet 8a in a non-contact state, and the gear angle sensor 8 is configured by the magnet 8a and the magnetism detecting element 8b. It is configured.

  Signals output from the rotary body angle sensor 6 and the gear angle sensor 8 are transmitted to the arithmetic unit 9, where the arithmetic unit 9 processes and electrically converts the voltage into waveforms (see FIG. 4). ).

  In the above configuration, when the steering wheel is rotated, the rotating body 2 is rotated at the same time, and the arm 5 is rotated three times from the outermost side of the groove portion 2b (or from the outermost periphery which is intermediate between the outermost and innermost periphery). It may be the position of the eye.) Starting from the starting point, it moves while drawing an arc-shaped locus in the inner circumferential direction. Here, the rotation of the steering wheel is locked-to-locked with 6 rotations, so the rotating body 2 also rotates 6 times at maximum. The rotating body angle sensor 6 does not output the output signal as a reset signal every time the arm 5 makes one round of the groove 2b as in the above-described Technical Example 3, and the output signal from the rotating body angle sensor 6 is a voltage. Converted. FIG. 4A is a waveform diagram obtained by processing conversion of the output signal from the rotating body angle sensor 6 showing this. The waveform is linear. This waveform gradually increases from the starting 1V voltage, and reaches 4V when the rotating body 2 rotates six times clockwise, for example. When the voltage reaches 4V and the rotating body 2 stops rotating, the voltage is reset to 1V and the steering is rotated counterclockwise, and a waveform having a phase opposite to that in FIG. 4A is formed.

  Since the gear 7 meshes with the first teeth 2a of the rotating body 2, when the rotating body 2 rotates, the gear 7 also rotates simultaneously. As the gear 7 rotates, the magnetic force of the magnet 8a attached to the gear 7 gradually changes. The magnetic detection element 8b detects the intensity of this change, and transmits the detection signal to the arithmetic unit 9.

  The calculation unit 9 generates a waveform diagram obtained by calculating the received detection signal and converting it to a voltage. FIG. 4B is a waveform diagram showing this waveform.

Here, for example, it is assumed that the rotational speed of the gear 7 is set to four times that of the rotating body 2. Then, when the rotating body 2 rotates 6 times, the gear 7 rotates 24 times. The magnetic detection element 8b outputs a signal of one cycle every time the magnet 8a rotates 180 degrees. Therefore, when the rotator 2 rotates at a constant angular velocity, every time the rotator 2 rotates 45 degrees from the magnetic detection element 8b, the sawtooth signals Q ₁ , Q ₂ , Q ₃ ,. Cycle. Therefore, for example, if the center of the inner and outer periphery of the groove 2a (the outer periphery of the six-turn spiral groove or the third winding position from the inner periphery) is set as the neutral position of the steering, the sawtooth signals Q ₁ , Q ₂ , Q ₃ ,... Are generated 12 times each in the left and right (FIG. 4) direction of the neutral position. However, the steering is locked-to-locked when the steering wheel rotates three times clockwise and counterclockwise from the neutral position.

  As described above, the calculation unit 9 produces a linear voltage waveform as shown in FIG. 4 (a) from the rotating body angle sensor 6 and from the gear angle sensor 8 as shown in FIG. 4 (b). A sawtooth voltage waveform is obtained. Therefore, for example, an arithmetic processing circuit that takes the waveform from the angle sensor 6 for the rotating body as the main, the waveform from the angle sensor 8 for the gear as the sub, and measures the rotation angle (absolute angle) of the rotating body 2 from these two waveforms. By incorporating it in the arithmetic circuit 7, the resolution of the rotation angle (absolute angle) of the rotating body 2 can be further increased. For example, a certain point P1 on the waveform of FIG. 4A is projected on the waveform of FIG. 4B to obtain P2.

  Further, by separately processing the waveforms of FIGS. 4A and 4B, the rotational speed of the rotating body 2 can be detected from the waveform of FIG. The rotation angle (absolute angle) at the number of rotations of the rotating body 2 can be measured from the waveform of b).

  That is, not only can the voltage waveforms in FIGS. 4A and 4B be individually processed to increase the accuracy of the rotation angle (absolute angle) of the rotating body 2, but also the rotating body can be synthesized by synthesizing both voltage waveforms. The accuracy of the rotation angle (absolute angle) of 2 can be further increased.

  If the magnetic detection element 8b is an MR element, the angular position of the rotating body 2 in the direction of the magnetic force is detected as an absolute value even when the magnet 8a is stationary (the rotating body 2 and the gear 7 are not rotating). Therefore, the rotation angle (absolute angle) of the rotating body 2 does not go out of order even when the steering is rotated in a state where the power supply to the system of the rotation angle detection device 1 is cut off.

  Further, the linear waveform of FIG. 4A obtained from the output signal of the angle sensor 6 for the rotating body is for detecting the rotation angle (absolute angle) of the rotating body 2 with higher accuracy as the inclination angle θ is larger. Is considered advantageous. This is because if the voltage change is increased by a slight rotation of the rotating body 2, the inclination angle θ is also increased proportionally, so that a subtle voltage change can be detected in analog. This inclination angle θ is affected by the groove width of the groove 2a and the interval between the grooves. For example, if the dimension between the grooves is increased, the movement locus of the arm 4b is increased, so that the inclination angle θ is also increased. However, in order to do this, the diameter of the rotating body 2 must be increased inevitably, which goes against the downsizing of the apparatus. In this regard, in the present invention, even if the inclination angle θ is reduced and the inclination gradient is a gentle waveform, the arithmetic circuit can read the waveform of FIG. 4B at a certain waveform point in FIG. Is also incorporated, so that a high resolution of the rotation angle (absolute angle) of the rotating body 2 can be obtained.

  FIG. 5 shows a linear tracking system in which the arm 5 is fixed to the position sensor 6a for the rotating body, and the head 4 as a moving body can be moved along the arm 5 in the direction of the arrow shown in the figure. . According to this method, the head 4 can eliminate the overhang generated by the pickup method, and the spiral groove can be traced more reliably.

  As described above, according to the rotation angle detection device of the present invention, (1) the driving main body is configured by the rotating body, the simple moving body, and one gear, and therefore the apparatus can be made compact. (2) By correlating the waveforms obtained from the angle sensor for the rotating body and the angle sensor for the gear, the rotation angle (absolute angle) of the rotating body with high resolution can be measured.

It is a principal part perspective view of one Example of the rotation angle detection apparatus of this invention. It is a top view of FIG. FIG. 6 is a sectional view of a moving body head and a groove portion of a rotating body. It is a waveform output diagram in the arithmetic circuit, (a) is a waveform diagram obtained from the angle sensor for rotating bodies, (b) is a waveform diagram obtained from the angle sensor for gears. It is the other example of attachment of the moving body with respect to an arm. It is a perspective view of the rotation angle detection apparatus of the technical example 1. FIG. It is a perspective view of the rotation angle detection apparatus of the technical example 2. FIG. It is a top view of the rotation angle detection apparatus of the technical example 3.

Explanation of symbols

1, 10, 20 Rotation angle detection device
30 Rotation sensor
2 Rotating body
2b Groove
3 Steering shaft
4 moving objects
6 Angle sensor for rotating body
7 Gear
8 Angle sensor for gears
9 Calculation unit

Claims (5)

A rotating body having first teeth and having a spiral groove formed on the upper surface;
A moving body that moves along the groove of the rotating body;
An angle sensor for a rotating body that detects a moving angle of the moving body when the rotating body rotates;
A gear having a second tooth meshing with the first tooth of the rotating body, and rotating with the rotation of the rotating body;
A gear angle sensor for detecting a rotation angle of the gear;
A rotation angle detection apparatus comprising: an arithmetic unit that detects a rotation angle of the rotating body based on both output signals of the rotating body angle sensor and the gear angle sensor.   The rotation angle detection device according to claim 1, wherein the number of teeth of the second teeth of the gear is smaller than the number of teeth of the first teeth of the rotating body.   The rotation angle detection device according to claim 1, wherein the angle sensor for the rotating body and the angle sensor for the gear perform angle detection by a Hall element or a magnetoresistive element.   2. The rotation angle detection device according to claim 1, wherein the movable body is a head that is attached to one end of an arm that rotates in an arc shape around a fulcrum and is positioned in the groove.   The moving body is a head movably attached to a fixed arm orthogonal to the groove portion, and the rotating body angle sensor is a rotating body position sensor that detects a moving position of the moving body. The rotation angle detection device according to claim 1, wherein the rotation angle detection device is a rotation angle detection device.

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