JP2017215184A - Rotation angle detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotation angle detector that makes it possible to improve angle accuracy.SOLUTION: A steering angle sensor 1 is provided with a housing 2 through which a shaft connected to steering is penetrated. Inside the housing 2 is arranged a main gear 3 that rotates integrally with the shaft in linkage with the rotary operation of steering. A sub-gear 5 engages the main gear 3. A metal plate 4 integrally provided in the main gear 3 has its projection 4a, which is a part to be measured, displaced in accordance with the rotation angle of the main gear 3. On a substrate 6 arranged in the housing 2, there is set a copper pattern 7 in correspondence to the movement track of the projection 4a. The rotation angle of the main gear 3 is directly detected by an eddy current sensor that includes the metal plate 4 and the copper pattern 7. The possibility of a backlash between the main gear 3 and the sub-gear 5 constituting an angle error is reduced.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a rotation angle detection device that detects a rotation angle of a rotating body.

Patent Document 1 discloses an angle sensor that detects a rotation operation angle of a steering as an example of a rotation angle detection device.
As shown in FIG. 2, the angle sensor 31 includes a housing 32 through which a shaft connected to the steering is passed. A main gear 33 that rotates integrally with the shaft is arranged in the housing 32 in conjunction with the rotation operation of the steering.

  A first sub gear 34 is meshed with the main gear 33, and a second sub gear 35 having a different number of teeth is meshed with the first sub gear 34. A first magnet 36 is assembled to the first sub gear 34, and a second magnet 37 is assembled to the second sub gear 35. A first magnetoresistive element is provided corresponding to the first magnet 36, and a second magnetoresistive element is provided corresponding to the second magnet 37.

  The magnetic field direction of the first magnet 36 is detected by the first magnetoresistive element, and the magnetic field direction of the second magnet 37 is detected by the second magnetoresistive element. Each magnetoresistive element outputs an electric signal indicating the rotation angle of the sub gear according to the magnetic field direction of the corresponding magnet. By analyzing the electric signal, the absolute angle of the steering can be calculated from the difference in rotation angle between the first sub gear 34 and the second sub gear 35.

JP 2012-225916 A

The backlash between the main gear 33 and the first sub gear 34 becomes an angle error, and it is difficult to improve accuracy.
The present invention has been made paying attention to such problems, and an object of the present invention is to provide a rotation angle detection device capable of improving the angle accuracy.

  A rotation angle detection device that solves the above-described problem is a rotation angle detection device that detects a rotation angle of a rotating body, a main gear that rotates in conjunction with the rotation of the rotating body, a sub gear that meshes with the main gear, and the main gear A first sensor that directly detects a physical quantity corresponding to the rotation angle of the main gear and outputs a first electric signal indicating the rotation angle of the main gear; and detects a physical quantity corresponding to the rotation angle of the sub gear to detect the physical quantity of the sub gear. The gist of the present invention is to include a second sensor that outputs a second electrical signal indicating a rotation angle.

  According to this configuration, in detecting the rotation angle of the rotating body, the physical quantity corresponding to the rotation angle of the main gear is directly detected by the first sensor. For this reason, the backlash between the main gear and the sub gear becomes an angular error in detection by the first sensor. Therefore, the angle accuracy can be improved.

  With respect to the rotation angle detection device, the first sensor is opposed to the main gear and a detected object that is provided integrally with the main gear and whose measured portion is displaced to generate a physical quantity corresponding to the rotation angle of the main gear. And a detector that detects the physical quantity generated by the object to be detected and outputs the first electric signal indicating the rotation angle of the main gear.

  According to this configuration, an object to be detected is set in the main gear, and the rotation angle of the rotating body can be directly detected in the range of 0 ° to 360 ° by the first sensor including the object to be detected and the detector. Further, the number of rotations of the rotating body can be detected by the first sensor and the second sensor. Therefore, the absolute angle of the rotating body exceeding 360 ° can be calculated from both detections.

  In the rotation angle detection device, the detector includes an excitation coil that is excited while an excitation signal is applied, and a detection coil in which a number of closed loops that define resolution of the rotation angle of the main gear are set, and the detection In the coil, the induced electromotive force generated due to the magnitude of eddy current generated by electromagnetic induction with the exciting coil is changed for a closed loop where the measured part by the conductor faces, and the first sensor The eddy current sensor outputs the first electric signal indicating the rotation angle associated with the closed loop in which the induced electromotive force is changed while the rotation angle of the main gear is associated with each closed loop of the detection coil. Also good.

  According to this configuration, high accuracy can be realized by a system combining eddy current sensors.

  According to the present invention, angular accuracy can be improved.

The top view which shows typically the structure of a rudder angle sensor in a to-be-detected side and a detection side. The top view which shows the structure of an angle sensor.

Hereinafter, an embodiment of the rotation angle detection device will be described.
As shown in FIG. 1, a rudder angle sensor 1 as an example of a rotation angle detecting device includes a housing 2 through which a shaft connected to a steering (rotating body) (not shown) is passed. The housing 2 has an outer shape formed by a combination of a circle and a rectangle, and the center of the circle coincides with the center of the circular hole for penetrating the shaft. A main gear 3 that rotates integrally with the shaft is arranged in the housing 2 in conjunction with the rotation operation of the steering.

  The main gear 3 has an insulating resin as a base, and a ring-shaped metal plate 4 is insert-molded or assembled. In the metal plate 4, the protrusion 4 a that is a part to be measured is displaced according to the rotation angle of the main gear 3. The metal plate 4 corresponds to an object to be detected. The main gear 3 is meshed with a sub gear 5 having a smaller diameter than the main gear 3. A magnet (not shown) is assembled to the sub gear 5.

  By the way, in the housing 2, there is a substrate 6 whose center coincides with the circular hole of the housing 2, has a circular hole that is slightly larger than the circular hole of the housing 2, and whose outer dimension is slightly smaller than that of the housing 2. Has been placed. A copper pattern 7 is set on the substrate 6 corresponding to the movement locus of the protrusion 4 a of the metal plate 4.

  The copper pattern 7 includes an excitation coil that is excited while being supplied with an excitation signal, and a detection coil in which a number of closed loops that define the resolution of the rotation angle of the main gear 3 are set. The copper pattern 7 corresponds to a detector. The copper pattern 7 constitutes a first sensor together with the metal plate 4. In this example, the first sensor is an eddy current sensor based on the following principle.

  That is, when the excitation coil is excited, an induced electromotive force is generated in the detection coil due to the magnitude of eddy current generated by electromagnetic induction with the excitation coil. When the main gear 3 rotates in conjunction with the steering rotation operation, the induced electromotive force of the detection coil changes in the closed loop where the protrusion 4a of the metal plate 4 faces. Therefore, on the assumption that the rotation angle of the main gear 3 is associated with each closed loop of the detection coil, the rotation angle of the steering is set to 0 ° while specifying the rotation angle associated with the closed loop in which the induced electromotive force has changed. It can be detected directly in the range of ~ 360 °.

  The induced electromotive force generated in the detection coil corresponds to a first electric signal indicating the rotation angle of the main gear 3. However, the magnetic flux is absorbed by the protrusion 4a and the amount of magnetic flux passing through the closed loop is reduced for the closed loop where the protrusion 4a of the metal plate 4 faces. In this connection, the amount of magnetic flux passing through the closed loop corresponds to a physical quantity corresponding to the rotation angle of the main gear 3.

  An MRE (magnetoresistive element) 8 is mounted on the substrate 6 so as to correspond to the magnet of the sub gear 5. The MRE 8 and the magnet of the sub gear 5 constitute a second sensor. When the main gear 3 rotates in conjunction with the rotation operation of the steering and the sub gear 5 meshed with the main gear 3 rotates, the electrical resistance of the MRE 8 changes according to the magnetic field direction of the magnet of the sub gear 5. Therefore, it is possible to identify the rotation angle of the sub gear 5 from the voltage derived from the electrical resistance of the MRE 8 and to detect the rotation speed of the steering from the combination of the identified rotation angle of the sub gear 5 and the rotation angle of the main gear 3 at that time. become.

  The voltage derived from the electric resistance of the MRE 8 corresponds to a second electric signal indicating the rotation angle of the sub gear 5. However, the magnetic field direction of the magnet of the sub gear 5 corresponds to a physical quantity corresponding to the rotation angle of the sub gear 5.

  Further, a control IC (not shown) that performs overall control related to detection of the rotational operation angle of the steering is mounted on the substrate 6. The control IC supplies an excitation signal to the excitation coil of the copper pattern 7, monitors the induced electromotive force generated in the detection coil, and monitors the voltage derived from the electrical resistance of the MRE 8. Then, the control IC calculates the absolute angle of the steering based on both monitoring results.

Next, the operation of the rudder angle sensor 1 will be described.
On the assumption that the exciting coil of the copper pattern 7 is excited by the control IC mounted on the substrate 6, the user rotates the steering. Then, in conjunction with the rotation operation of the steering, the main gear 3 rotates together with the shaft, and the sub gear 5 meshed with the main gear 3 rotates.

  At this time, the protrusion 4a of the metal plate 4 is displaced according to the rotation angle of the main gear 3, and among the plurality of closed loops set in the detection coil of the copper pattern 7, the amount of magnetic flux passing through the closed loop to which the protrusion 4a faces. And the magnitude of eddy current generated in the closed loop changes. As a result, the control IC specifies the rotation angle of the main gear 3 associated with the closed loop in which the induced electromotive force has changed due to the eddy current, and directly controls the rotation operation angle of the steering in the range of 0 ° to 360 °. To detect.

  On the other hand, according to the rotation angle of the sub gear 5, the magnetic field direction of the magnet of the sub gear 5 with respect to the MRE 8 changes, and the electric resistance of the MRE 8 changes. Thereby, the control IC specifies the rotation angle of the sub gear 5 from the voltage derived from the electrical resistance of the MRE 8 and determines the steering angle from the combination of the specified rotation angle of the sub gear 5 and the rotation angle of the main gear 3 at that time. Detect the number of rotations.

Then, the control IC calculates the absolute angle of the steering based on the detection result of the steering operation angle and the detection result of the number of rotations of the steering.
As described above, according to the present embodiment, the following effects can be obtained.

  (1) In detecting the rotation operation angle of the steering, the physical quantity corresponding to the rotation angle of the main gear 3 is directly detected by the first sensor (including the metal plate 4 and the copper pattern 7). For this reason, the backlash between the main gear 3 and the sub gear 5 becomes an angular error in the detection by the first sensor. Therefore, the angle accuracy can be improved.

  (2) A metal plate 4 is set on the main gear 3, and the rotation operation angle of the steering can be directly detected in the range of 0 ° to 360 ° by the first sensor including the metal plate 4 and the copper pattern 7. Further, the rotational speed of the steering can be detected by the first sensor (including the metal plate 4 and the copper pattern 7) and the second sensor (including the magnet of the sub gear 5 and the MRE 8). Therefore, the absolute angle of the steering exceeding 360 ° can be calculated from both detections.

(3) High accuracy can be realized by combining the eddy current sensors.
(4) In comparison with the angle sensor 31 shown in FIG. 2, the second magnet 37 and the second magnetoresistive element set together with the second sub gear 35 are reduced in addition to the second sub gear 35. Reduce the size of one gear.

In addition, the said embodiment can also be changed and actualized as follows.
As a part to be measured, a notch may be set on the metal plate 4 instead of the protrusion 4a, and the copper pattern 7 may be set on the substrate 6 in accordance with the movement locus of the notch. In this case, since the induced electromotive force generated in the closed loop is changed while the amount of magnetic flux passing through the closed loop is increased for the closed loop in which the notch of the metal plate 4 is opposed, the steering is performed as in the above embodiment. Can be detected directly in the range of 0 ° to 360 °.

The rotation angle of the main gear 3 may be directly detected by an optical sensor or the like instead of the eddy current sensor.
The second sensor related to the detection of the rotation angle of the sub gear 5 only needs to be able to detect the number of rotations of the steering in cooperation with the first sensor related to the detection of the rotation angle of the main gear 3, and is higher as the first sensor. Angular accuracy is not required. In view of this point, it is possible to adopt a method combining a relatively simple magnetic sensor (including the magnet of the sub gear 5 and the MRE 8) according to the above embodiment. However, instead of the magnetic sensor, an optical sensor or an eddy current sensor may be adopted as the second sensor.

Next, a technical idea that can be grasped from the above embodiment and another example will be described.
(A) In the rotation angle detection method for detecting the rotation angle of the rotating body, the rotation angle of the main gear rotating in conjunction with the rotation of the rotating body is directly detected by the first sensor and meshed with the main gear. The rotation angle of the sub gear is detected by the second sensor.

  (B) In the rotation angle detection method, the rotation angle of the rotating body is directly detected by the first sensor in the range of 0 ° to 360 °, and the first sensor and the second sensor Detecting the number of rotations of a rotating body.

  DESCRIPTION OF SYMBOLS 1 ... Rudder angle sensor (rotation angle detection apparatus), 2 ... Housing, 3 ... Main gear, 4 ... Metal plate (1st sensor, to-be-detected object, eddy current sensor), 4a ... Projection (measurement part), 5 ... Sub-gear (second sensor), 6 ... substrate, 7 ... copper pattern (first sensor, detector, eddy current sensor), 8 ... MRE (second sensor).

Claims (3)

In the rotation angle detection device for detecting the rotation angle of the rotating body,
A main gear that rotates in conjunction with the rotation of the rotating body;
A sub gear meshed with the main gear;
A first sensor that directly detects a physical quantity corresponding to the rotation angle of the main gear and outputs a first electric signal indicating the rotation angle of the main gear;
And a second sensor for detecting a physical quantity corresponding to the rotation angle of the sub gear and outputting a second electric signal indicating the rotation angle of the sub gear. The first sensor is provided integrally with the main gear, and the object to be measured is displaced to generate a physical quantity corresponding to the rotation angle of the main gear, and the first sensor is disposed to face the main gear while being opposed to the main gear. The rotation angle detection device according to claim 1, further comprising: a detector that detects a physical quantity generated by a detection object and outputs the first electric signal indicating the rotation angle of the main gear. The detector includes an excitation coil that is excited while an excitation signal is applied, and a detection coil in which a number of closed loops that define the resolution of the rotation angle of the main gear are set,
For the detection coil, the induced electromotive force generated due to the magnitude of the eddy current generated by electromagnetic induction with the excitation coil is changed for a closed loop where the measured part by the conductor is opposed,
The first sensor is a vortex that outputs the first electric signal indicating the rotation angle associated with the closed loop in which the induced electromotive force is changed while the rotation angle of the main gear is associated with each closed loop of the detection coil. The rotation angle detection device according to claim 2, wherein the rotation angle detection device is a current sensor.

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