Sensor System

Abstract

The present invention concerns a sensor system for monitoring at least the wear of lining material of a disc brake. It may also be used to monitor the stroke of the brake actuator. The sensor system uses the position of an adjusting mechanism or a thrust plate as an indication of the wear of the lining material. The sensor system is mounted in a way to use a caliper of the disc brake as a measuring reference. The sensor system comprises a memory arranged to receive a value of the detected wear and comprises a logic circuit arranged to indicate if the brake is in a released position or not.

1 . A sensor system for monitoring at least the wear of lining material of disc brakes, using the position of an adjusting mechanism or a thrust plate as an indication of the wear of the lining material, characterized in that the sensor system is mounted in a way to use a caliper of the disc brake as a measuring reference, that the sensor system comprises a memory arranged to receive a value of the detected wear, and that the sensor system comprises a logic circuit arranged to indicate if the brake is in a released position or not.  
   
   
       2 . The sensor system of  claim 1 , characterized in that it comprises a first sensor monitoring and giving a signal indicative of the occurrence of a brake movement.  
   
   
       3 . The sensor system of  claim 2 , characterized in that the first sensor is a part of the control and monitoring system of the vehicle.  
   
   
       4 . The sensor system of  claim 2 , characterized in that a fixed point for measurements is defined by the first sensor and/or that the first sensor comprises a sensing element using Hall effect for co-operation with a magnet.  
   
   
       5 . The sensor system of  claim 4 , characterized in that the magnet is received on a holder fixed to a lever arm of the brake mechanism and that the first sensor is received on a printed circuit board.  
   
   
       6 . The sensor system of  claim 4 , characterized in that the magnet is received on a rotating part of the adjusting mechanism and/or that the magnet has the form a magnetic washer moving axially in the adjusting mechanism.  
   
   
       7 . The sensor system of  claim 1 , characterized in that it comprises a second sensor monitoring and giving a signal indicative of the actual position of the part indicating the wear of the brake lining material.  
   
   
       8 . The sensor system of  claim 7 , characterized in that the logic circuit is using the second sensor.  
   
   
       9 . The sensor system of  claim 7 , characterized in that the second sensor is linear.  
   
   
       10 . The sensor system of  claim 9 , characterized in that the second sensor is a force sensor, a Hall effect sensor received on a printed circuit board a light sensor, a sound sensor, a mechanical sensor, an electrical transducer or a GMR sensor and/or that the second sensor co-operates with a magnetic tube placed inside the adjusting mechanism.  
   
   
       11 . The sensor system of  claim 7 , characterized in that the major part of the sensor system is received on a cap fixed to the caliper.  
   
   
       12 . The sensor system of  claim 1 , characterized in that the logic circuit uses an algorithm to establish the occurrence of a brake movement.  
   
   
       13 . A method for monitoring at least the wear of lining material of disc brakes, comprising the steps of: 
 sensing the position of an adjustment mechanism or a thrust plate with a caliper as a measuring reference;    storing the value of detected wear in a memory;    indicating whether or not a brake is in a released condition with a logic circuit; and    determining if the brake is in a correct predetermined position for measuring wear based on the indication.    
   
   
       14 . The method of  claim 13 , further comprising the step of measuring either the wear of the brake lining material or the stroke of the brake actuation utilizing the step of sensing the position of the adjustment mechanism or the thrust plate.  
   
   
       15 . The method of  claim 14 , further comprising the steps of establishing whether a brake cycle has started or not and determining which type of measurement is possible at that moment.  
   
   
       16 . The method of  claim 14 , characterized in that a signal indicating the wear of the brake lining material is used to update the memory.