Shielded position sensor for translationally moving parts

Abstract

A sensor is disclosed for monitoring a part which can move translationally relative to a sensor with reference to its position on the axis of motion. This part is for example a piston in a cylinder which is equipped with a sensor. The sensor can be actuated by means of a magnet which is oriented in the direction of motion with respect to the north and south pole and which is located on the movable part. The sensor has three reed contacts which are aligned in parallel and of which the first and the second reed contact are located in one plane and parallel next to one another with their lengthwise axes, by which they can be actuated almost at the same time by the magnetic field of the magnet which is located on the movable part. The third reed contact is located at a distance to the plane of the first and the second reed contact. This sensor with the first two reed contacts is mounted facing the actuating magnet. This arrangement has the advantage that an external magnetic field always actuated the third reed contact as well, if it can actuate the first two reed contacts. Then the sensor indicates an error report or an unsafe position, but never a safe position of the movable part.

What is claimed is: 
     
         1 . Sensor for monitoring a part which can move translationally relative to the sensor with reference to a position on an axis of motion, comprising:
 a magnet which is located on the movable part; and   a fastening means which prevents shifting of the sensor in a direction of motion of the part, which fastening means connects the sensor to a carrier for the sensor, and wherein there is a spring means for maintaining a form-fit of the fastening means.   
     
     
         2 . Sensor as claimed in  claim 1 , wherein the sensor on opposing ends is provided with one mounting tail each, and wherein there are two catch heads, the mounting tail being provided with teeth and each catch head being provided with a catch mechanism which engages the teeth, such that in interaction the two catch heads are slipped onto one mounting tail at a time, but the catch heads are prevented from being pulled off. 
     
     
         3 . Sensor as claimed in  claim 1 , wherein the sensor is equipped with two catch mechanisms which work in opposition, and wherein there are two fixing parts with one mounting tail each and a stop head, the mounting tail being provided with teeth, such that in interaction with one of the catch mechanisms on the sensor the two fixing parts are slipped onto the sensor, but the fixing parts are prevented from being pulled off. 
     
     
         4 . Sensor as claimed in  claim 3 , wherein the fastening means encompasses a sensor body. 
     
     
         5 . Sensor as claimed in  claim 4 , wherein the fastening means is a spring element which has been released from the sensor. 
     
     
         6 . Sensor as claimed in  claim 1 , comprising:
 a fastening means which has at least one tooth which can be pressed into a surface of a groove which holds the sensor.