Sensor arrangement
View Patent ↗A sensor arrangement and a method for its use for detecting the proximity of a ferrous target, the sensor arrangement comprising a sensor body including a magnetic field source and a Hall effect device, wherein the magnetic field source is an electromagnetic solenoid. The invention has particularly utility, but is not so limited, to the field of fuel injection pumps in which it is necessary to determine the volume of fuel that is delivered to the cylinders of the engine without affecting the operation of the engine.
1. A sensor arrangement for detecting the proximity of a ferrous target, the sensor arrangement comprising a sensor module including a magnetic field source and a Hall effect device, wherein the magnetic field source is an electromagnetic solenoid, wherein the sensor arrangement includes a control unit which receives an electrical output signal from the Hall effect device and supplies a drive current signal to the electromagnetic solenoid, wherein the control unit includes a closed loop control circuit arranged to receive the electrical output signal of the Hall effect device and operable to modulate the drive current signal of the electromagnetic solenoid so as to maintain the magnetic field strength in a region between the Hall effect device and the ferrous target at a substantially constant level.
2. The sensor arrangement of claim 1 , wherein the Hall effect device is aligned with a longitudinal axis of the electromagnetic solenoid.
3. The sensor arrangement of claim 1 , wherein the Hall effect device and the electromagnetic solenoid are arranged as a single package.
4. The sensor arrangement of claim 1 , wherein the control system is arranged to periodically disable the drive current signal to the electromagnetic solenoid.
5. The sensor arrangement of claim 1 wherein the drive current signal to the electromagnetic solenoid is used as an indicator of the position of the ferrous target.