US 4,914,389 A · Multiturn shaft position sensor with backlash compensation

Abstract

The present invention is a shaft position sensor for detection of the position of a multiturn shaft. The rotation of the multiturn shaft is converted into a linear motion via a multiturn screw and two axially spaced non-rotating nuts which are oppositely continuously axially biased by intermediate compressed springs. A magnet is mounted on one of the nonrotating nuts. The linear movement of the magnet is converted into an electrical signal using a magneto resistive structure. A pair of flux plates is disposed on either side of the linear path of the magnet with a narrow gap opposite one end of the linear path of the magnet. The magneto resistive structure is disposed in the narrow gap. An electrical circuit measures the resistance of the magneto resistive structure, this resistance varying with magnetic flux, and generates an electrical position signal which indicates the rotary position of the multiturn shaft. Linearity in response can be provided by a flux shunt which blocks magnetic flux directly from the magnet, control of the distance of the flux plates from the linear path of the magnet.

Claims11

Dependent claims

A multiturn shaft position sensor for detecting the position of a multiturn shaft comprising:

a multiturn screw disposed to turn with the multiturn shaft;
first and second axially spaced nonrotating nuts mounted on said multiturn screw for linear movement dependent upon the turning of said multiturn screw;
biasing means reacting between said nonrotating nuts to simultaneously bias said nuts in opposite directions along the axis of said multiturn screw;
a magnet disposed upon said first nonrotating nut for linear movement along a predetermined movement path from a first end to a second end with said linear movement of said first nonrotating nut;
a pair of flux plates formed of a material of high magnetic permeability disposed on opposite sides of said movement path of said magnet having a narrow gap therebetween opposite said first end of said movement path;
a magneto resistive structure disposed in said narrow gap between said pair of flux plates having an electrical resistance dependent upon the magnetic flux therethrough;
and
an electrical circuit connected to said magneto resistive structure for measuring said electrical resistance of said magneto resistive structure and generating a position signal indicative of the position of the multiturn shaft proportional to said electrical resistance of said magneto resistive structure.

5 more elements

A multiturn shaft position sensor for detecting the position of a multiturn shaft comprising:

a magnet for generating magnetic flux;
a means connected to the multiturn shaft and said magnet for converting multiturn motion of the multiturn shaft into linear motion of said magnet along a predetermined movement path;
means continuously biasing said means connected to the multiturn shaft in one direction along the axis of said multiturn shaft;
at least one magneto resistive structure disposed for receiving said magnetic flux from said magnet which differs depending upon the location of said magnet along said movement path, said at least one magneto resistive structure having an electrical resistance dependent on the magnitude of received magnetic flux;
an electrical circuit connected to said at least one magneto resistive structure for measuring said electrical resistance of said at least one magneto resistive structure and generating a position signal indicative of the position of the multiturn shaft proportional to said electrical resistance of said at least one magneto resistive structure.

2 more elements

Dependencies are inferred from the claim text.

Multiturn shaft position sensor with backlash compensation

Life of this patent

Multiturn shaft position sensor with backlash compensation

Life of this patent

Abstract

Claims11