JP2021189041A - Rotation angle detector - Google Patents

Abstract

To suppress reduction of the accuracy of detecting a rotation angle detector.SOLUTION: A plurality of detection target units 13a as conductors are arranged along the direction in which a steering shaft rotates, and are displaced with rotation of the steering shaft. A first detection unit 15 outputs a first detection signal S1 for a physical amount that changes according to an eddy current flowing in each detection target unit 13a.SELECTED DRAWING: Figure 1

Description

The present invention relates to a device for detecting the rotation angle of a rotating body.

Patent Document 1 discloses, as an example of a rotation angle detecting device, a sensor that detects the rotation angle of a steering shaft accompanying steering of a vehicle. The sensor includes a main gear coupled to the steering shaft and a sub gear that meshes with the main gear. A magnet is attached to the sub gear. The rotation angle of the steering shaft is specified by detecting the change in the direction of the magnetic field with the rotation of the sub gear by the magnetic sensor.

Japanese Unexamined Patent Publication No. 2012-225916

An object of the present invention is to suppress a decrease in detection accuracy of the rotation angle detecting device.

One aspect for achieving the above object is a rotation angle detecting device for detecting the rotation angle of a rotating body.
A plurality of conductors arranged along the rotation direction of the rotating body and displaced in the rotation direction with the rotation of the rotating body, and
A first detection unit that outputs a first detection signal corresponding to a physical quantity that changes due to an eddy current flowing through each of the plurality of conductors.
It is equipped with.

In the configuration described in Patent Document 1, the rotation angle of the steering shaft is detected by specifying the rotation amount of the sub gear that meshes with the main gear. In such a configuration, a detection error may occur due to the backlash between the main gear and the sub gear. On the other hand, according to the above configuration, the physical quantity changed by the eddy current flowing through the plurality of conductors displaced in the rotation direction with the rotation of the rotating body is directly detected, so that a detection error occurs. It is suppressed. In addition, since the detection angle range assigned to each conductor is set to less than 360 ° by providing a plurality of conductors, the occurrence of detection error is further suppressed. Therefore, it is possible to suppress a decrease in the detection accuracy of the steering angle detecting device.

The configuration of the rotation detection device according to one embodiment is illustrated. An example is a rotation detection device mounted on a steering shaft.

An example of the embodiment will be described in detail below with reference to the accompanying drawings. In each drawing used in the following description, the scale is appropriately changed in order to make each member a recognizable size.

FIG. 1 illustrates the configuration of the steering angle detecting device 10 according to the embodiment. As illustrated in FIG. 2, the steering angle detecting device 10 is mounted on a steering shaft 20 used for steering a moving body. The steering shaft 20 is connected to a steering member such as a steering wheel. When the steering force is input through the steering member, the steering shaft 20 rotates about the rotation axis A. The steering angle detecting device 10 is configured to detect the rotation angle of the steering shaft 20 accompanying steering. The steering angle detection device 10 is an example of a rotation angle detection device. The steering shaft 20 is an example of a rotating member.

The steering angle detecting device 10 includes a first support 11. The first support 11 is formed of a material having electrical insulating properties such as resin. The first support 11 has a through hole 11a. The first support 11 is non-rotatably coupled to the steering shaft 20. At this time, a part of the steering shaft 20 is arranged in the through hole 11a.

The steering angle detecting device 10 includes a second support 12. The second support 12 is formed of a material having electrical insulating properties such as resin. The second support 12 has a through hole 12a. The second support 12 is arranged so that the steering shaft 20 rotatably extends in the through hole 12a.

The steering angle detecting device 10 includes a first conductive portion 13. The first conductive portion 13 is formed of a conductive material such as metal. The first conductive portion 13 is supported by the first support 11. The first conductive portion 13 has a plurality of detected portions 13a. In this example, the number of the plurality of detected portions 13a is eight. The plurality of detected portions 13a are arranged along the circumferential direction of the through hole 11a on the radial outside of the through hole 11a of the first support 11. Each of the plurality of detected portions 13a extends in the radial direction.

The steering angle detecting device 10 includes a second conductive portion 14. The second conductive portion 14 is formed of a conductive material such as metal. The second conductive portion 14 is supported by the second support 12. The second conductive portion 14 is arranged on the radial outer side of the through hole 12a of the second support 12.

When the steering angle detection device 10 is mounted on the steering shaft 20, the first conductive portion 13 supported by the first support 11 and the second conductive portion 14 supported by the second support 12 face each other. Placed in.

The second conductive portion 14 includes an exciting coil that is excited while being supplied with an exciting signal, and a detection coil that is set with a number of closed loops that define the resolution of the rotation angle of the steering shaft 20. When the exciting coil is excited, an induced electromotive force derived from the magnitude of the eddy current flowing through the detected portion 13a of the first conductive portion 13 due to electromagnetic induction with the exciting coil is generated in the detection coil. When the first support 11 rotates together with the steering shaft 20, the induced electromotive force changes in the detection coil having a closed loop in which the detected portion 13a of the first conductive portion 13 faces. Further, in the detection coil having a closed loop facing the detected portion 13a of the first conductive portion 13, the amount of the magnetic flux passing through the closed loop is reduced by the absorption of the magnetic flux by the detected portion 13a.

Therefore, if the rotation angle of the first support 11 is associated with each closed loop of the detection coil, the rotation angle of the steering shaft 20 can be specified by specifying the rotation angle associated with the closed loop in which the dielectric electromotive force or the amount of passing magnetic flux changes. The rotation angle can be detected. In this example, since the eight detected portions 13a are arranged at equal intervals along the rotation direction of the steering shaft 20, the rotation angle of the steering shaft 20 can be detected in the range of 0 ° to 45 °.

The rudder angle detection device 10 includes a first detection unit 15. The first detection unit 15 includes a circuit that supplies the above-mentioned excitation signal to the excitation coil of the second conductive unit 14, and a circuit that detects a change in the induced electromotive force or the amount of passing magnetic flux generated in the detection coil of the second conductive unit 14. I have. These circuits are supported by the second support 12. The first detection unit 15 is configured to output a first detection signal S1 corresponding to a change in the induced electromotive force or the amount of passing magnetic flux. The induced electromotive force or the amount of passing magnetic flux is an example of a physical quantity.

In the configuration described in Patent Document 1, the rotation angle of the steering shaft is detected by specifying the rotation amount of the sub gear that meshes with the main gear corresponding to the first support 11. In such a configuration, a detection error may occur due to the backlash between the main gear and the sub gear. On the other hand, according to the above configuration, the physical quantity changed by the eddy current flowing in the detected portion 13a of the first conductive portion 13 that is displaced in the direction of the rotation of the steering shaft 20 is directly detected. Therefore, the occurrence of detection error is suppressed. In addition, since the detection angle range assigned to each detected unit 13a is set to less than 360 ° by providing the plurality of detected units 13a, the occurrence of detection error is further suppressed. Therefore, it is possible to suppress a decrease in the detection accuracy of the steering angle detecting device 10.

As illustrated in FIG. 1, the first conductive portion 13 has an annular portion 13b. The annular portion 13b extends along the circumferential direction of the through hole 11a. That is, the annular portion 13b extends along the rotation direction of the steering shaft 20. The ends of the plurality of detected portions 13a on the side close to the through holes 11a are connected to each other by the annular portion 13b.

According to such a configuration, since the area affected by the electromagnetic induction by the second conductive portion 14 is expanded, the eddy current flowing through the detected portion 13a can be increased. As a result, the change in the induced electromotive force or the amount of passing magnetic flux generated in the detection coil of the second conductive portion 14 can be increased, so that the deterioration of the detection accuracy of the first detection unit 15 can be suppressed. However, the annular portion 13b may be omitted.

As illustrated in FIG. 1, the rudder angle detecting device 10 may include a sub gear 16. In this case, a plurality of teeth 11b that mesh with the sub gear 16 are formed on the outer peripheral portion of the first support 11. The number of the plurality of teeth 16a formed on the sub gear 16 is smaller than the number of the plurality of teeth 11b formed on the first support 11. The first support 11 is an example of the first gear. The sub gear 16 is an example of the second gear. The plurality of teeth 11b is an example of the plurality of first teeth. The plurality of teeth 16a is an example of the plurality of second teeth.

The steering angle detection device 10 may further include a second detection unit 17. The second detection unit 17 is supported by the second support 12. The second detection unit 17 is configured to output the second detection signal S2 corresponding to the rotation amount of the sub gear 16. In this example, the second detection unit 17 includes a magnetoresistive element. On the other hand, the magnet 16b is mounted on the sub gear 16. The direction of the magnetic field generated from the magnet 16b changes according to the rotation of the sub gear 16. The resistance value of the magnetoresistive element changes according to the change. The second detection signal S2 corresponds to the resistance value.

As described above, since the first conductive unit 13 has a plurality of detected units 13a, the occurrence of the angle detection error is suppressed, while the first detection signal S1 output from the first detection unit 15 is suppressed. The detectable angle range is limited to less than 360 ° (45 ° in this example). However, by combining the rotation amount of the sub gear 16 specified based on the second detection signal S2, any angle exceeding 45 ° can be detected. Therefore, it is possible to widen the detectable angle range while suppressing the occurrence of the angle detection error by using the first conductive portion 13 having the plurality of detected portions 13a.

The above embodiments are merely examples for facilitating the understanding of the present invention. The configuration according to the above embodiment may be appropriately changed or improved without departing from the spirit of the present invention.

In the above embodiment, the amount of rotation of the sub gear 16 is magnetically detected. In this case, it is easy to simplify the configuration of the second detection unit 17. However, the second detection unit 17 may be configured so that the rotation amount of the sub gear 16 is optically or mechanically detected.

In the above embodiment, the steering angle detecting device 10 is used to specify the rotation angle of the steering shaft 20. However, the rotation angle detecting device according to the present invention can be applied to an appropriate member that requires detection of rotation.

In that case, the number of the plurality of detected portions 13a included in the first conductive portion 13 is appropriately determined according to the range of the rotation angle of the detected rotating body. In the above embodiment, the plurality of detected portions 13a are arranged at equal intervals along the rotation direction of the rotating body. According to such a configuration, angle management becomes easy, especially when the rotation angle of the rotating body is specified in combination with the rotation amount of the sub gear 16. However, depending on the angle range of the detected rotating body, the arrangement spacing of the plurality of detected portions 13a does not necessarily have to be equal.

10: Steering angle detection device, 11: First support, 11b: Multiple teeth, 13a: Detected part, 15: First detection part, 16: Sub gear, 16a: Multiple teeth, 17: Second detection part, 20: Steering shaft, S1: First detection signal, S2: Second detection signal

Claims (5)

A rotation angle detection device that detects the rotation angle of a rotating body.
A plurality of conductors arranged along the rotation direction of the rotating body and displaced in the rotation direction with the rotation of the rotating body, and
A first detection unit that outputs a first detection signal corresponding to a physical quantity that changes due to an eddy current flowing through each of the plurality of conductors.
Is equipped with
Rotation angle detector. A first gear that supports the plurality of conductors and has a plurality of first teeth,
A second gear that meshes with the first gear and has a plurality of second teeth that are less than the first tooth.
A second detection unit that outputs a second detection signal corresponding to the rotation amount of the second gear, and
Is equipped with
The rotation angle detecting device according to claim 1. The second detection unit magnetically detects the amount of rotation of the second gear.
The rotation angle detecting device according to claim 2. The plurality of conductors are arranged at equal intervals along the rotation direction.
The rotation angle detecting device according to any one of claims 1 to 3. The plurality of conductors are connected to each other by the conductor extending in the rotational direction.
The rotation angle detecting device according to any one of claims 1 to 4.

Images