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DE-102019122188-B4 - ANGLE SENSOR SYSTEM

DE102019122188B4DE 102019122188 B4DE102019122188 B4DE 102019122188B4DE-102019122188-B4

Abstract

Angle sensor system (100), comprising: a magnetic field generator (5) for generating a detection target magnetic field, wherein the detection target magnetic field is a magnetic field to be detected and is referenced to an angle to be detected; and an angle sensor (1) for detecting the target magnetic field and for generating an angle detection value which corresponds to the angle to be detected, characterized in that the angle sensor (1) has: a first magnetic sensor (10) for detecting a first applied magnetic field, comprising the target magnetic field for detection, at a first detection position and for generating first detection information corresponding to the angle to be detected; a second magnetic sensor (20) for detecting a second applied magnetic field, comprising the target magnetic field, at a second detection position and for generating second detection information corresponding to the angle to be detected; and a processor (30) for generating the angle detection value by performing arithmetic processing using the first detection information and the second detection information; the direction of the target magnetic field changes at both the first and second detection positions according to the angle to be detected; the detection target magnetic field has a first strength at the first detection position and a second strength at the second detection position, wherein the ratio of the second strength to the first strength is 1.65 or more, the magnetic field generator (5) has a magnetic structure (206) which is formed from a magnetic material, wherein the magnetic structure (206) has a magnetization in a direction perpendicular to an axis of rotation and when the magnetic structure (206) rotates around the axis of rotation, it rotates itself around the axis of rotation, the first detection position and the second detection position are located on the same side of the magnetic structure (206) in a direction parallel to the axis of rotation and are spaced at different distances from the axis of rotation, the magnetic structure (206) has a first section (261) and a second section (262) which are coupled together, wherein the second section (262) is located between the first section (261) and the first and second detection positions in the direction parallel to the axis of rotation, the second section (262) has a cavity (262h) through which the axis of rotation passes, whereas the first section (261) has no cavity through which the axis of rotation passes, the first section (261) has a section (261A) of soft magnetic material, which is formed from a soft magnetic material, and a section (261B) of hard magnetic material, which is formed from a hard magnetic material, The section (261B) made of hard magnetic material has a receiving section (261Ba) through which the axis of rotation passes, and the section (261A) made of soft magnetic material is received in the receiving section (261Ba).

Inventors

  • Yongfu CAI
  • Hiraku Hirabayashi

Assignees

  • TDK CORPORATION

Dates

Publication Date
20260513
Application Date
20190819
Priority Date
20180919

Claims (11)

  1. Angle sensor system (100), comprising: a magnetic field generator (5) for generating a target magnetic field, wherein the target magnetic field is a magnetic field to be detected and is referenced to an angle to be detected; and an angle sensor (1) for detecting the target magnetic field and for generating an angle detection value corresponding to the angle to be detected, characterized in that the angle sensor (1) comprises: a first magnetic sensor (10) for detecting a first applied magnetic field, comprising the target magnetic field, at a first detection position and for generating first detection information corresponding to the angle to be detected; a second magnetic sensor (20) for detecting a second applied magnetic field, comprising the target magnetic field, at a second detection position and for generating second detection information corresponding to the angle to be detected; and a processor (30) for generating the angle detection value by performing arithmetic processing using the first detection information and the second detection information; the direction of the target magnetic field changes at both the first and second detection positions according to the angle to be detected; the detection target magnetic field has a first strength at the first detection position and a second strength at the second detection position, wherein the ratio of the second strength to the first strength is 1.65 or more; the magnetic field generator (5) has a magnetic structure (206) formed from a magnetic material, wherein the magnetic structure (206) has magnetization in a direction perpendicular to an axis of rotation and rotates about the axis of rotation when the magnetic structure (206) is rotated; the first detection position and the second detection position are located on the same side of the magnetic structure (206) in a direction parallel to the axis of rotation and are spaced at different distances from the axis of rotation; the magnetic structure (206) has a first section (261) and a second section (262) coupled to each other, wherein the second section (262) is located between the first section (261) and the first and second detection positions in a direction parallel to the axis of rotation; the second section (262) has a cavity (262h) through which the axis of rotation passes, whereas the first section (261) has no cavity through which the axis of rotation passes, the first section (261) has a section (261A) of soft magnetic material formed from a soft magnetic material, and a section (261B) of hard magnetic material formed from a hard magnetic material, the section (261B) of hard magnetic material has a receiving section (261Ba) through which the axis of rotation passes, and the section (261A) of soft magnetic material is received in the receiving section (261Ba).
  2. Angle sensor system (100), comprising: a magnetic field generator (5) for generating a target magnetic field, wherein the target magnetic field is a magnetic field to be detected and is referenced to an angle to be detected; and an angle sensor (1) for detecting the target magnetic field and for generating an angle detection value corresponding to the angle to be detected, characterized in that the angle sensor (1) comprises: a first magnetic sensor (10) for detecting a first applied magnetic field, comprising the target magnetic field, at a first detection position and for generating first detection information corresponding to the angle to be detected; a second magnetic sensor (20) for detecting a second applied magnetic field, comprising the target magnetic field, at a second detection position and for generating second detection information corresponding to the angle to be detected; and a processor (30) for generating the angle detection value by performing arithmetic processing using the first detection information and the second detection information; the direction of the target magnetic field changes at both the first and second detection positions according to the angle to be detected; the detection target magnetic field has a first strength at the first detection position and a second strength at the second detection position, wherein the ratio of the second strength to the first strength is 1.65 or more, the magnetic field generator (5) has a magnetic structure (6; 106; 206) which is formed from a magnetic material, wherein the magnetic structure (6; 106; 206) has a magnetization in a direction perpendicular to an axis of rotation and rotates itself about the axis of rotation when the magnetic structure (6; 106; 206) is rotated about the axis of rotation, the first detection position and the second detection position are on the same side of the magnetic structure (6; 106; 206) in a direction parallel to the axis of rotation and are spaced at different distances from the axis of rotation, the magnetic structure (6; 106; 206) has a first section (61; 161; 261) and a second section (62; 162; 262) which are coupled together, wherein the second section (62; 162; 262) is located between the first section (61; 161; 261) and the first and second detection positions in the direction parallel to the axis of rotation, the second section (62; 162; 262) has a cavity (62h, 162h; 262h) through which the axis of rotation passes, whereas the first section (61; 161; 261) has no cavity through which the axis of rotation passes, when viewed in a direction parallel to the axis of rotation, both the first detection position (P1) and the second detection position (P2) are placed to intersect the cavity (62h; 162h; 262h) of the second section (62; 162; 262).
  3. Angle sensor system (100) according to Claim 2 , wherein the magnetic structure (6; 106) is formed in its entirety from a hard magnetic material.
  4. Angle sensor system (100) according to Claim 2 , wherein the first section (261) comprises a section (261A) of soft magnetic material formed from a soft magnetic material and a section (261B) of hard magnetic material formed from a hard magnetic material, the section (261B) of hard magnetic material comprising a receiving section (261Ba) through which the axis of rotation passes, and the section (261A) of soft magnetic material is received in the receiving section (261Ba).
  5. Angle sensor system (100) according to one of the Claims 1 until 4 , where the ratio of the second strength to the first strength is 4 or less.
  6. Angle sensor system (100) according to one of the Claims 1 until 5 , wherein a rotating field angle corresponds to the angle to be detected, wherein the rotating field angle is an angle formed by the direction of the detection target magnetic field at a reference position with respect to a reference direction on a reference plane, and the angle detection value corresponds to the rotating field angle.
  7. Angle sensor system (100) according to Claim 6 , wherein the first angle detection information corresponds to an angle which forms a direction of a first applied field component with respect to the reference direction, wherein the first applied field component is a component of the first applied magnetic field which is parallel to the reference plane, and the second detection information corresponds to an angle which forms a direction of a second applied field component with respect to the reference direction, wherein the second applied The field component is a component of the second applied magnetic field that lies parallel to the reference plane.
  8. Angle sensor system (100) according to Claim 7 , wherein the first acquisition information includes a first acquisition value corresponding to a cosine of the angle formed by the direction of the first applied field component with respect to the reference direction, and a second acquisition value corresponding to a sine of the angle formed by the direction of the first applied field component with respect to the reference direction, and the second acquisition information includes a third acquisition value corresponding to a cosine of the angle formed by the direction of the second applied field component with respect to the reference direction, and a fourth acquisition value corresponding to a sine of the angle formed by the direction of the second applied field component with respect to the reference direction.
  9. Angle sensor system (100) according to one of the Claims 6 until 8 , where the first and second recording positions lie in the reference plane.
  10. Angle sensor system (100) according to one of the Claims 1 until 9 , wherein the first section (61; 161; 261) is shaped as a circular plate, and the second section (62; 162; 262) has an outer circumference and an inner circumference, each of which has a circular shape in any cross-section of the second section (62; 162; 262) perpendicular to the axis of rotation.
  11. Angle sensor system (100) according to the Claim 1 , wherein, when viewed in the direction parallel to the axis of rotation, the first detection position is placed to intersect the cavity (262h) of the second section (262), and the second detection position is placed to intersect the second section (262) but not the cavity (262h).

Description

BACKGROUND OF THE INVENTION 1. Technical field The present invention relates to an angle sensor system for generating an angle detection value which corresponds to an angle to be detected. 2. State of the art In recent years, angle sensors have been widely used in various applications, such as detecting the rotational position of a steering wheel or a power steering motor in an automobile. Angle sensors generate an angle measurement value, which corresponds to the angle being measured. Examples of angle sensors include magnetic angle sensors. An angle sensor system using a magnetic angle sensor is typically equipped with a magnetic field generator to create a detectable magnetic field whose direction changes in response to the rotation or linear movement of an object. Hereinafter, the detectable magnetic field is referred to as the target magnetic field. The magnetic field generator is, for example, a magnet. The angle to be detected by the magnetic angle sensor corresponds to the angle formed by the direction of the target magnetic field at a reference position relative to a reference direction. One well-known magnetic angle sensor is one that, as in DE 10 2012 100 194 A1 , DE 10 2017 122 475 A1 and DE 10 2018 101 909 A1 The invention discloses a plurality of sensing circuits for generating a plurality of sensing signals of different phases and generating an angle sensing value by performing arithmetic operations using the plurality of sensing signals. Each of the plurality of sensing circuits detects a target magnetic field. Each of the plurality of sensing circuits has at least one magnetic sensing element. In some magnetic angle sensors, as in DE 10 2017 122 475 A1 and DE 10 2018 101 909 A1 Each detection circuit is described as being subject not only to a target magnetic field but also to a magnetic interference field that is not the target magnetic field. Examples of magnetic interference fields include the Earth's magnetic field and stray magnetic fields from a motor. When subjected to such a magnetic interference field, each detection circuit detects a composite magnetic field consisting of the target magnetic field and the magnetic interference field. If the target magnetic field and the magnetic interference field are oriented in different directions, errors occur in the angle detection value. These errors in the angle detection value are referred to below as the angle error. DE 10 2017 122 475 A1 and DE 10 2018 101 909 A1 They describe a technology for detecting the composite magnetic field consisting of the target magnetic field and the magnetic interference field at a multitude of detection positions and use the detection information to generate an angular detection value that reduces error caused by the magnetic interference field. The target magnetic field exhibits varying strengths at the multiple detection positions. According to the in DE 10 2017 122 475 A1 and DE 10 2018 101 909 A1 The described technology enables the use of acquisition information from two magnetic sensors arranged at two different positions to generate an angle measurement value in which error caused by the magnetic interference field is reduced. However, research carried out by the inventor of the present invention has shown that the effect varies depending on the design of the two magnetic sensors. US 6 479 987 B1 and US 2014 / 0 015 384 A1 Each figure shows an angle sensor system known in the prior art. US 2010 / 0 176 804 A1 shows an angle sensor with a ring magnet suitable for mounting on a rotatable shaft. BRIEF SUMMARY OF THE INVENTION One object of the present invention is to provide an angle detection system which effectively reduces an angular error caused by a magnetic interference field by using two magnetic sensors. An angle sensor system according to the present invention comprises a magnetic field generator and an angle sensor. The magnetic field generator produces a target magnetic field, which is a magnetic field to be detected and is referenced to a specific angle. The angle sensor detects the target magnetic field and generates an angle detection value that corresponds to the angle to be detected. The angle sensor comprises a first magnetic sensor, a second magnetic sensor, and a processor. The first magnetic sensor detects a first applied magnetic field at a detection position, possessing the target magnetic field, and generates initial detection information corresponding to the angle to be measured. The second magnetic sensor detects a second applied magnetic field at a second detection position, also possessing the target magnetic field, and generates further detection information corresponding to the angle to be measured. The processor generates the angle measurement value by performing arithmetic processing using the first and second detection information. At both the first and second detection positions, the direction of the target magnetic field changes according to the angle being detected. Th