Brake monitoring system

Abstract

A vehicle brake monitor for a brake actuator including a housing, a reciprocal push rod extending through an opening in the housing and a stone shield mounted in the housing opening. An annular sleeve surrounds the push rod which is integrally formed of plastic including opposed sleeve portions which are generally semicircular in cross-section and a longitudinal integral flexible hinge portion interconnecting the adjacent sides of the sleeve portions, such that the annular sleeve may be received on the push rod, and an adjustable connector element interconnecting the opposed sides of the sleeve portions. The sleeve includes an elongated magnet, preferably a ceramic magnet having face portions which are magnetized with adjacent north and south poles and the stone shield includes a Hall-effect sensor which senses the location of the sleeve as the push rod reciprocates through the stone shield.

1 . A vehicle brake monitor, comprising: 
 at least one service chamber defined by a cup shaped housing and a cover; said housing defining an opening having a pushrod for actuating a brake slidably inserted therethrough;    a sleeve circumscribing said pushrod and defining a pocket having an elongated magnet disposed therein oriented generally parallel to an axis of said pushrod, wherein said sleeve derives reciprocating movement through said opening from said pushrod;    a stone shield circumscribing said sleeve and being positioned adjacent said housing substantially sealing said opening around said sleeve thereby preventing stones and debris from entering said chamber through said opening, said stone shield comprising two interconnecting parts having a sensor disposed in one of said parts for sensing the location of said magnet relative to said stone shield when said sleeve is reciprocating through said opening.    
     
     
         2 . A vehicle brake monitor set forth in    claim 1   , wherein said sleeve includes a key and said stone shield includes a keyway guiding said sleeve in a longitudinal direction through said opening thereby maintaining said magnet in a position proximate to said sensor.  
     
     
         3 . A vehicle brake monitor set forth in    claim 1   , wherein said sensor comprises a Hall effect sensor potted in one of said interconnecting parts of said stone shield proximate to said magnet thereby determining the location of said pushrod by detecting a change in magnetic field emitted by said magnet.  
     
     
         4 . A method of assembling a brake monitor for monitoring the disposition of a brake, comprising the steps of: 
 affixing a sensor to a stone shield utilized to seal an opening in a service chamber of a brake actuation assembly;    positioning a sleeve having a magnet affixed thereto onto a pushrod of said brake actuation assembly;    adjusting the position of said sleeve on said pushrod thereby positioning said magnet in a fixed location relative to said pushrod;    inserting said pushrod into said opening disposed in said service chamber through said stone shield; and    
       adjusting the position of said sensor affixed to said stone shield relative to said magnet disposed in said sleeve to monitor the location of said pushrod.  
     
     
         5 . A method as set forth in    claim 4    further including the step of clamping said sleeve onto said pushrod thereby affixing the location of said magnet relative to said pushrod.  
     
     
         6 . A method as set forth in    claim 4    wherein said step of inserting said pushrod through said stone shield is further defined by securing semicircular sections of said stone shield around said pushrod.  
     
     
         7 . A method as set forth in    claim 4    wherein said step of adjusting the position of said sensor relative to said stone shield is further defined by inserting a key on said sleeve through a keyway on said stone shield.