Magnetoresistive type position sensor having bias magnetic and magnet resistance elements in bias magnetic field thereof

• US 6,020,736 A
• Filed: 08/07/1995
• Issued: 02/01/2000
• Est. Priority Date: 08/25/1994
• Status: Expired due to Term

• Current Assignee: Nippondenso Co., Ltd. (DENSO Corporation)
• Original Assignee: Nippondenso Co., Ltd. (DENSO Corporation)
• Inventors: Izawa, Ichiro, Aoyama, Seiki, Makino, Yasuaki, Kuroyanagi, Susumu, Shoji, Izuru
• Primary Examiner(s): Snow, Walter E.
• Application Number:
  US08/511,621
• Time in Patent Office: 1,639 Days
• Field of Search: 324/207.2, 324/207.21, 324/207.25, 324/174, 324/207.22, 338/32 R, 338/32 H, 341/15
• US Class Current: 324/207.21
• CPC Class Codes: G01D 5/147 influenced by the movement of a third element, the position of Hall device and the source of magnetic field being fixed in respect to each other
• CPC Class Codes: G01P 3/488 delivered by variable reluctance detectors

Abstract

A rotation object is made of a magnetic material and disposed within a predetermined range of an angle of rotation on a plane perpendicular to an axis of rotation. A bias magnet generates a bias magnetic field to the rotation body in a direction perpendicular to the axis of rotation. Magnetic resistance elements are disposed in the bias magnetic field on a plane including the axis of rotation at a position deviated from the position of the rotation object in the axial direction of the rotation body and inclined by about 45° relative to a direction perpendicular to the axis of rotation.

Claims

1. A position sensor comprising:

an object to be detected made of a magnetic material fixed to a body of rotation and disposed within a predetermined range of an angle of rotation on a plane perpendicular to an axis of the body of rotation;

a bias magnet magnetized in an axial direction thereof for generating a bias magnetic field to the body of rotation in a direction perpendicular to the axis of the body of rotation, said bias magnet being disposed radially outwardly of the object; and

a magnetic resistance element disposed in the bias magnetic field generated directly from said bias magnet, at a position deviated from the position of disposing the object to be detected in an axial direction of the body of rotation and detecting a direction of a magnetic vector in the axial direction of the body of rotation, said magnetic resistance element being positioned on a plane which extends from one magnetic pole side of said bias magnet in the axial direction of said bias magnet, whereby said magnetic resistance element is subjected to a greatest possible magnetic field.

2. A position sensor as defined in claim 1, wherein the object to be detected includes a first semi-circular tooth.

3. A position sensor as defined in claim 2, wherein the object to be detected further includes a second semi-circular tooth and the first tooth and the second tooth are spaced apart from each other in a circumferential direction of the body of rotation.

10. A position sensor according to claim 1, wherein said bias magnet comprises a single permanent magnet, and said magnetic resistance element is disposed between said object to be detected and said one magnetic pole side.

11. A position sensor according to claim 1, further comprising:

a circuit connected to said magnetic resistance element to convert a change in a resistance of said magnetic resistance element into a corresponding electrical signal in a pulse form.

16. A position sensor as defined in claim 3, wherein the first tooth and the second tooth are spaced apart from each other in the axial direction of the body of rotation.

18. A position sensor as defined in claim 1, wherein the body of rotation is driven by an engine and an output signal of the magnetic resistance element is used to discriminate a cylinder number of the engine.

24. A position sensor according to claim 1, wherein the plane where the magnetic resistance element is positioned thereon extends from one magnetic pole side of said bias magnet in a direction of the magnetic field generated directly from the bias magnet.

26. A position sensor according to claim 11, wherein said circuit includes a comparator for comparing said corresponding electrical signal in said pulse form and a predetermined voltage.

29. A position sensor according to claim 1, wherein a component of the magnetic field in a direction of deflection thereof is perpendicular to a plane containing the object to be detected throughout an entire rotation of the body.

30. A position sensor according to claim 1, wherein the object to be detected includes a pair of teeth disposed at axially spaced positions in said axial direction of the body of rotation and wherein the magnetic resistance element is disposed axially between but radially outside the pair of teeth.

31. A position sensor according to claim 30, wherein said teeth are disposed perpendicularly to the axis of the body of rotation.

33. A position sensor according to claim 1, wherein the object to be detected includes a first tooth and a second tooth positioned in respective planes parallel to each other and with an axial spacing therebetween, with the magnetic resistance element disposed within the axial spacing of the first tooth and the second tooth to be responsive to a deflection of direction of the bias magnetic field.

34. A position sensor according to claim 33, wherein the magnetic resistance element includes a pair of magnetic resistance components connected in series and further comprising a comparing circuit connected to the magnetic resistance components to compare a signal of the magnetic resistance components at a junction between the magnetic resistance components with a reference signal.

4. A position sensor comprising:

an object to be detected made of a magnetic material fixed to a body of rotation and disposed within a predetermined range of an angle of rotation on a plane perpendicular to an axis of the body of rotation;

a bias magnet magnetized in an axial direction thereof for generating a bias magnetic field to the body of rotation in a direction perpendicular to the axis of the body of rotation; and

a magnetic resistance element disposed in the bias magnetic field generated directly from said bias magnet, at a position deviated from the position of disposing the object to be detected in an axial direction of the body of rotation and detecting a direction of a magnetic vector in the axial direction of the body of rotation, said magnetic resistance element being positioned on a plane which extends from one magnetic pole side of said bias magnet in the axial direction of said bias magnet, whereby said magnetic resistance element is subjected to a greatest possible magnetic field, wherein the magnetic resistance element is disposed on a plane including the axis of the body of rotation and inclined by about 45°

relative to a direction perpendicular to the axis of the body of rotation.

20. A position sensor according to claim 4, wherein said bias magnet comprises a single permanent magnet, and said magnetic resistance element is disposed between said object to be detected and said one magnetic pole side.

21. A position sensor according to claim 4, further comprising:

a circuit connected to said magnetic resistance element to convert a change in a resistance of said magnetic resistance element into a corresponding electrical signal in a pulse form.

35. A position sensor according to claim 4, wherein the object to be detected includes a first tooth and a second tooth positioned in respective planes parallel to each other and with an axial spacing therebetween, with the magnetic resistance element disposed within the axial spacing of the first tooth and the second tooth to be responsive to a deflection of direction of the bias magnetic field.

36. A position sensor according to claim 35, wherein the magnetic resistance element includes a pair of magnetic resistance components connected in series and further comprising a comparing circuit connected to the magnetic resistance components to compare a signal of the magnetic resistance components at a junction between the magnetic resistance components with a reference signal.

5. A position sensor comprising:

an object to be detected made of a magnetic material, fixed to a body of rotation, so as to be disposed at a predetermined radius from an axis of the body of rotation and extending in parallel to and in an axial direction of said axis of the body of rotation and disposed within a predetermined range of an angle of rotation on a plane perpendicular to the axis of the body of rotation;

a bias magnet magnetized in an axial direction thereof for generating a bias magnetic field to the body of rotation in a direction parallel with the axis of the body of rotation; and

a magnetic resistance element disposed in the bias magnetic field generated directly from said bias magnet, at a position deviated from a position of disposing the object to be detected in a radial direction of the body of rotation and detecting a direction of a magnetic vector in a radial direction of the body of rotation, said magnetic resistance element being positioned away from one magnetic pole side of said bias magnet in a direction of said magnetic field generated directly from said bias magnet and in the axial direction of said bias magnet, whereby said magnetic resistance element is subjected to a greatest possible magnetic field.

6. A position sensor as defined in claim 5, wherein the object to be detected includes a first semi-annular ridge.

7. A position sensor as defined in claim 6, wherein the object to be detected further includes a second semi-annular ridge, and the first ridge and the second ridge are spaced apart from each other in a circumferential direction of the body of rotation.

12. A position sensor according to claim 5, wherein said bias magnet comprises a single permanent magnet, and said magnetic resistance element is disposed between said object to be detected and said one magnetic pole side.

13. A position sensor according to claim 5, further comprising:

a circuit connected to said magnetic resistance element to convert a change in a resistance of said magnetic resistance element into a corresponding electrical signal in a pulse form.

17. A position sensor as defined in claim 7, wherein the first ridge and the second ridge are spaced apart from each other in the radial direction of the body of rotation.

19. A position sensor as defined in claim 5, wherein the body of rotation is driven by an engine and an output signal of the magnetic resistance element is used to discriminate a cylinder number of the engine.

25. A position sensor according to claim 5, wherein said magnetic resistance element is positioned on a plane which extends from one magnetic pole side of said bias magnet in the axial direction of said bias magnet.

27. A position sensor according to claim 13, wherein said circuit includes a comparator for comparing said corresponding electrical signal in said pulse form and a predetermined voltage.

32. A position sensor according to claim 5, wherein the magnetic resistance element is disposed at a position spaced apart from the object in the axial direction of the bias magnet.

37. A position sensor according to claim 5, wherein the object to be detected includes a first tooth and a second tooth with a radial spacing therebetween, with the magnetic resistance element disposed within the radial spacing of the first tooth and the second tooth to be responsive to a deflection of direction of the bias magnetic field.

38. A position sensor according to claim 37, wherein the magnetic resistance element includes a pair of magnetic resistance components connected in series and further comprising a comparing circuit connected to the magnetic resistance components to compare a signal of the magnetic resistance components at a junction between the magnetic resistance components with a reference signal.

8. A position sensor comprising:

an object to be detected made of a magnetic material, fixed to a body of rotation, having a predetermined radius coaxial with an axial center of the body of rotation and disposed within a predetermined range of an angle of rotation on a plane perpendicular to the axis of the body of rotation;

a bias magnet magnetized in an axial direction thereof for generating a bias magnetic field to the body of rotation in a direction parallel with the axis of the body of rotation; and

a magnetic resistance element disposed in the bias magnetic field generated directly from said bias magnet, at a position deviated from a position of disposing the object to be detected in a radial direction of the body of rotation and detecting a direction of a magnetic vector in a radial direction of the body of rotation, said magnetic resistance element being positioned away from one magnetic pole side of said bias magnet in a direction of said magnetic field generated directly from said bias magnet and in the axial direction of said bias magnet, whereby said magnetic resistance element is subjected to a greatest possible magnetic field, wherein the magnetic resistance element is disposed on a plane including the axis of the body of rotation and inclined by about 45°

relative to a direction parallel to the axis of the body of rotation.

22. A position sensor according to claim 8, wherein said bias magnet comprises a single permanent magnet, and said magnetic resistance element is disposed between said object to be detected and said one magnetic pole side.

23. A position sensor according to claim 8, further comprising:

a circuit connected to said magnetic resistance element to convert a change in a resistance of said magnetic resistance element into a corresponding electrical signal in a pulse form.

39. A position sensor according to claim 8, wherein the object to be detected includes a first tooth and a second tooth with a radial spacing therebetween, with the magnetic resistance element disposed within the radial spacing of the first tooth and the second tooth to be responsive to a deflection of direction of the bias magnetic field.

40. A position sensor according to claim 39, wherein the magnetic resistance element includes a pair of magnetic resistance components connected in series and further comprising a comparing circuit connected to the magnetic resistance components to compare a signal of the magnetic resistance components at a junction between the magnetic resistance components with a reference signal.

9. A position sensor for detecting a position of a rotation body, said sensor comprising:

a first arcuate member extending circularly around the rotation body by a first predetermined angle of rotation of the rotation body;

a second arcuate member extending circularly around the rotation body by a second predetermined angle of rotation of the rotation body, said second arcuate member being spaced apart from the first arcuate member in a direction of rotation of the rotation body and in one of an axial direction and a radial direction relative to an axis of the rotation body;

a bias magnet magnetized in an axial direction thereof and disposed between the first arcuate member and the second arcuate member for generating a bias magnetic field in a direction perpendicular to the one of the axial direction and the radial direction, the direction of the bias magnetic field being varied by the first arcuate member and the second arcuate member; and

a sensing member disposed between the bias magnet and the rotation body and responsive to a change in the direction of the bias magnetic field, said sensing member being positioned away from one magnetic pole side of said bias magnet in a general direction of said magnetic field generated directly from said bias magnet and in the axial direction of said bias magnet whereby said sensing member is subjected to a greatest possible magnetic field.

14. A position sensor according to claim 9, wherein said bias magnet comprises a single permanent magnet, and said sensing member is disposed between said object to be detected and said one magnetic pole side.

15. A position sensor according to claim 9, further comprising:

a circuit connected to said sensing member to convert a change in a resistance of said sensing member into a corresponding electrical signal in a pulse form.

41. A position sensor according to claim 9, wherein the sensing member is positioned between the first and second arcuate members to be responsive to a deflection of direction of the bias magnetic field.

42. A position sensor according to claim 41, wherein the sensing member includes a pair of magnetic resistance components connected in series and further comprising a comparing circuit connected to the magnetic resistance components to compare a signal of the magnetic resistance components at a junction between the magnetic resistance components with a reference signal.

28. A position sensor comprising:

an object to be detected made of a magnetic material, fixed to a body of rotation and disposed within a predetermined range of an angle of rotation on a plane perpendicular to an axis of the body of rotation, including a semi-circular tooth;

a bias magnetic magnetized in an axial direction thereof for generating a bias magnet field to the body of rotation in a direction perpendicular to the axis of the body of rotation; and

a magnetic resistance element disposed in the bias magnetic field generated directly from said bias magnet, at a position deviated from the position of disposing the object to be detected in an axial direction of the body of rotation and detecting a direction of a magnetic vector in the axial direction of the body of rotation, said magnetic resistance element being positioned away from one magnetic pole side of said bias magnet in a direction of said magnetic field generated directly from said bias magnet and in the axial direction of said bias magnet, whereby said magnetic resistance element is subjected to a greatest possible magnetic field.

43. A position sensor according to claim 28, wherein the object to be detected includes a second semi-circular tooth, the first and second semi-circular teeth positioned in respective planes parallel to each other and with an axial spacing therebetween, with the magnetic resistance element disposed within the axial spacing of the first semi-circular tooth and the second semi-circular tooth to be responsive to a deflection of direction of the bias magnetic field.

44. A position sensor according to claim 43, wherein the magnetic resistance element includes a pair of magnetic resistance components connected in series and further comprising a comparing circuit connected to the magnetic resistance components to compare a signal of the magnetic resistance components at a junction between the magnetic resistance components with a reference signal.