Position detector with transmission parts defining varying gap width
AssigneeDenso Corporation
InventorsNaoaki Kouno, Tetsuji Yamanaka
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Abstract
A position detector has a gap for providing a detection range. The gap has a gap width that is greater at the ends of the gap than at a center. Therefore, an amount of a spill magnetic flux and an amount of a direct magnetic flux respectively flowing through a position at and around an end portion of the gap are reduced when compared to a gap having a constant gap width along the direction of relative movement. Namely, the density of magnetic flux which passes through a Hall element that is positioned at each longitudinal end of the gap decreases. Therefore, at or around the ends of the gap, a rate of change of the magnetic flux density detected by the Hall element decreases and the linearity of an output signal from the Hall element is improved.
Claims6
A position detector detecting a position of a detection object that moves relative to a reference part, the position detector comprising:
- a first magnetic flux transmission part disposed on one of the reference part or the detection object, the first magnetic flux transmission part having a first end and a second end;
- a second magnetic flux transmission part disposed to define a gap between the first magnetic flux transmission part and the second magnetic flux transmission part, the second magnetic flux transmission part having a first end and a second end;
- a first magnetic flux generator positioned between the first end of the first magnetic flux transmission part and the first end of the second magnetic flux transmission part;
- a second magnetic flux generator positioned between the second end of the first magnetic flux transmission part and the second end of the second magnetic flux transmission part;
- and
- a magnetic flux density detector positioned within the gap, disposed on another of the reference part or the detection object, and outputting a signal according to a density of a magnetic flux passing through the magnetic flux density detector, wherein
- the gap is defined by a first inside surface of the first magnetic flux transmission part and a second inside surface of the second magnetic flux transmission part, and
- each of the first inside surface and the second inside surface is a curved surface having a constant curvature radius,
- a gap width of the gap is defined as an orthogonal distance between the first magnetic flux transmission part and the second magnetic flux transmission part,
- a direction of relative movement is defined as a direction of movement of the magnetic flux density detector along the first magnetic flux transmission part,
- a range of movement is defined as a range of movement of the magnetic flux density detector within the gap,
- the gap width at each end position of the range of movement of the magnetic flux density detector along the direction of relative movement is greater than the gap width at a center of the range of movement of the magnetic flux density detector along the direction of relative movement, and
- an increase of the gap width from the center to each of the end positions of the range of movement of the magnetic flux density detector is a continuous increase between the center and each of the end positions,
- the first magnetic flux transmission part includes an outer arc portion, and
- the position detector further comprises an axial center of the range of movement, the first inside surface having a first center axis of curvature spaced apart from the axial center and located on one side of the axial center so that the first center axis of curvature is farther from the outer arc portion than the axial center is to the outer arc portion.
Dependencies are inferred from the claim text.