Patent ID: 9739638
Date: 2017-08-22
CPC Classifications: G01D

Claim:
1. A position sensing apparatus for sensing a position of a sensing subject, which moves relative to a reference member, the position sensing apparatus comprising: a first magnetic flux conducting member that extends in a moving direction of the sensing subject; a second magnetic flux conducting member that extends in the moving direction of the sensing subject in parallel with the first magnetic flux conducting member, wherein the first magnetic flux conducting member and the second magnetic flux conducting member are installed to one of the reference member and the sensing subject; a first magnetic flux generator that is placed between one end portion of the first magnetic flux conducting member and one end portion of the second magnetic flux conducting member; a second magnetic flux generator that is placed between another end portion of the first magnetic flux conducting member, which is opposite from the one end portion of the first magnetic flux conducting member in the moving direction of the sensing subject, and another end portion of the second magnetic flux conducting member, which is opposite from the one end portion of the second magnetic flux conducting member in the moving direction of the sensing subject; and a magnetic flux density sensing device that is placed in a gap between the first magnetic flux conducting member and the second magnetic flux conducting member and is installed to the other one of the reference member and the sensing subject, wherein: the magnetic flux density sensing device outputs an output signal, which corresponds to a density of the magnetic flux that passes through the magnetic flux density sensing device; the first magnetic flux conducting member and the second magnetic flux conducting member are opposed to each other in a predetermined direction that is defined as an opposing direction; the first magnetic flux conducting member has a first intermediate portion that is located between the one end portion and the other end portion of the first magnetic flux conducting member; when the first magnetic flux conducting member is viewed in the opposing direction, a width of the first intermediate portion, which is measured in a direction perpendicular to the moving direction of the sensing subject, is smaller than a width of the one end portion and a width of the other end portion of the first magnetic flux conducting member, which are measured in the direction perpendicular to the moving direction of the sensing subject; the width of the first intermediate portion is constant along an entire extent of the first intermediate portion in the moving direction of the sensing subject; the second magnetic flux conducting member has a second intermediate portion that is located between the one end portion and the other end portion of the second magnetic flux conducting member; when the second magnetic flux conducting member is viewed in the opposing direction, a width of the second intermediate portion, which is measured in the direction perpendicular to the moving direction of the sensing subject, is smaller than a width of the one end portion and a width of the other end portion of the second magnetic flux conducting member, which are measured in the direction perpendicular to the moving direction of the sensing subject; the width of the second intermediate portion is constant along an entire extent of the second intermediate portion in the moving direction of the sensing subject; and when the first magnetic flux conducting member and the second magnetic flux conducting member are viewed in the opposing direction, the width of the first intermediate portion of the first magnetic flux conducting member and the width of the second intermediate portion of the second magnetic flux conducting member are different from each other.