RELATIVE ANGLE DETECTION DEVICE, ROTATION ANGLE DETECTION DEVICE, RELATIVE ANGLE DETECTION METHOD, AND ROTATION ANGLE DETECTION METHOD

• US 20120256619A1
• Filed: 06/30/2010
• Published: 10/11/2012
• Est. Priority Date: 12/28/2009
• Status: Active Grant

• Current Assignee: Hitachi Astemo Ltd. (Hitachi, Ltd.)
• Original Assignee: Showa Corporation (Hitachi, Ltd.)
• Inventors: Muto, Hiroyuki, Okado, Kiyokazu, Suzuki, Tsukasa
• Granted Patent: US 8,810,237 B2
• Time in Patent Office: Days
• US Class Current: 324/207.12
• CPC Class Codes: G01D 2205/26 Details of encoders or position sensors specially adapted to detect rotation beyond a full turn of 360°, e.g. multi-rotation
• CPC Class Codes: G01D 2205/28 The target being driven in rotation by additional gears
• CPC Class Codes: G01D 5/04 using levers; using cams; using gearing
• CPC Class Codes: G01D 5/145 influenced by the relative movement between the Hall device and magnetic fields see G01R33/06

Abstract

Disclosed is a relative angle detection device for detecting a relative angle between a first rotary shaft and a second rotary shaft, the relative angle detection device being provided with a first magnetic field sensing unit which outputs a value according to a magnetic field of a magnet, a second magnetic field sensing unit which outputs a value according to the magnetic field of the magnet and outputs a value different from the output value of the first magnetic field sensing unit even if being placed in the same magnetic field as that of the first magnetic field sensing unit, a correction unit which corrects one output value out of the output value of the first magnetic field sensing unit and the output value of the second magnetic field sensing unit in accordance with an amplitude ratio between magnetic field components orthogonal to each other in the magnetic field of the magnet, and a computing unit which computes the relative angle between the first rotary shaft and the second rotary shaft on the basis of the one output value corrected by the correction unit and the other output value different from the one output value. Consequently, a technique capable of detecting the relative rotation angle with high accuracy is provided even if magnitudes of amplitudes of magnetic field components orthogonal to each other in the magnetically sensitive surface of the magnetic field sensing unit are different from each other.

Claims

1. A relative angle detection device that detects a relative angle between a first rotary shaft and a second rotary shaft, the relative angle detection device comprising:

a magnet that is provided to any one rotary shaft out of the first rotary shaft and the second rotary shaft;

a first magnetic field sensing unit that is provided to the other rotary shaft different from the one rotary shaft, and outputs a value according to a magnetic field of the magnet;

a second magnetic field sensing unit that is provided to the other rotary shaft, outputs a value according to a magnetic field of the magnet, and outputs a value different from an output value of the first magnetic field sensing unit even if being placed in a magnetic field equal to a magnetic field of the first magnetic field sensing unit;

a correction unit that corrects any one output value out of the output value of the first magnetic field sensing unit and an output value of the second magnetic field sensing unit in accordance with an amplitude ratio between magnetic field components orthogonal to each other in the magnetic field of the magnet; and

a computing unit that computes a relative angle between the first rotary shaft and the second rotary shaft on the basis of the one output value having been corrected by the correction unit and the other output value different from the one output value.

2. The relative angle detection device according to claim 1, wherein the correction unit makes a correction with a predetermined value in accordance with the amplitude ratio between the magnetic field components.

3. The relative angle detection device according to claim 1, further comprising a determination unit that determines a correction value according to the amplitude ratio between the magnetic field components, wherein

the correction unit corrects the one output value with the correction value determined by the determination unit.

4. The relative angle detection device according to claim 3, wherein the determination unit determines the correction value also in accordance with change of an environment where the first magnetic field sensing unit or the second magnetic field sensing unit is placed.

5. The relative angle detection device according to claim 3, wherein the determination unit determines the correction value on the basis of the output value of the first magnetic field sensing unit and the output value of the second magnetic field sensing unit.

6. The relative angle detection device according to claim 2, wherein the predetermined value or the correction value is a value according to an amplitude ratio between amplitude of a magnetic field component in a direction of a rotation radius of the first rotary shaft and amplitude of a magnetic field component in a circumferential direction of the first rotary shaft.

7. A rotation angle detection device that detects a rotation angle of a rotating body rotatably supported by a housing, the rotation angle detection device comprising:

a magnet that is provided to one component out of the rotating body and the housing;

a first magnetic field sensing unit that is provided to the other component out of the rotating body and the housing, different from the one component, and outputs a value according to a magnetic field of the magnet;

a second magnetic field sensing unit that is provided to the other component, outputs a value according to a magnetic field of the magnet, and outputs a value different from an output value of the first magnetic field sensing unit even if being placed at a magnetic field equal to a magnetic field of the first magnetic field sensing unit;

a correction unit that corrects any one output value out of the output value of the first magnetic field sensing unit and an output value of the second magnetic field sensing unit in accordance with an amplitude ratio between magnetic field components orthogonal to each other in the magnetic field of the magnet; and

a computing unit that computes a rotation angle of the rotating body on the basis of the one output value having been corrected by the correction unit and the other output value different from the one output value.

8. The rotation angle detection device according to claim 7, wherein the correction unit makes a correction with a predetermined value in accordance with the amplitude ratio between the magnetic field components.

9. The rotation angle detection device according to claim 7, further comprising a determination unit that determines a correction value according to the amplitude ratio between the magnetic field components, wherein

the correction unit corrects the one output value with the correction value determined by the determination unit.

10. The rotation angle detection device according to claim 9, wherein the determination unit determines the correction value also in accordance with change of an environment where the first magnetic field sensing unit or the second magnetic field sensing unit is placed.

11. The rotation angle detection device according to claim 9, wherein the determination unit determines the correction value on the basis of the output value of the first magnetic field sensing unit and the output value of the second magnetic field sensing unit.

12. The rotation angle detection device according to claim 8, wherein the predetermined value or the correction value is a value according to an amplitude ratio between amplitude of a magnetic field component in a direction of a rotation radius of the first rotary shaft and amplitude of a magnetic field component in a circumferential direction of the first rotary shaft.

13. A relative angle detection method of a relative angle detection device detecting a relative angle between a first rotary shaft and a second rotary shaft and including a magnet that is provided to any one rotary shaft out of the first rotary shaft and the second rotary shaft, a first magnetic field sensing unit that is provided to the other rotary shaft different from the one rotary shaft, and outputs a value according to a magnetic field of the magnet, and a second magnetic field sensing unit that is provided to the other rotary shaft, outputs a value according to a magnetic field of the magnet, and outputs a value different from an output value of the first magnetic field sensing unit even if being placed in a magnetic field equal to a magnetic field of the first magnetic field sensing unit, the relative angle detection method comprising:

correcting any one output value out of the output value of the first magnetic field sensing unit and an output value of the second magnetic field sensing unit in accordance with an amplitude ratio between magnetic field components orthogonal to each other in the magnetic field of the magnet; and

computing the relative angle between the first rotary shaft and the second rotary shaft on the basis of the one output value that has been corrected and the other output value different from the one output value.

14. A rotation angle detection method of a rotation angle detection device detecting a rotation angle of a rotating body rotatably supported by a housing, and including a magnet that is provided to one component out of the housing and the rotating body, a first magnetic field sensing unit that is provided to the other component out of the housing and the rotating body, different from the one component, and outputs a value according to a magnetic field of the magnet, and a second magnetic field sensing unit that is provided to the other component, outputs a value according to a magnetic field of the magnet, and outputs a value different from an output value of the first magnetic field sensing unit even if being placed at a magnetic field equal to a magnetic field of the first magnetic field sensing unit, the rotation angle detection method comprising:

correcting any one output value out of the output value of the first magnetic field sensing unit and the output value of the second magnetic field sensing unit in accordance with an amplitude ratio between magnetic field components orthogonal to each other in the magnetic field of the magnet; and

computing the rotation angle of the rotating body on the basis of the one output value that has been corrected and the other output value different from the one output value.