Lock detection sensor

Abstract

A differential gear mechanism, of either the locking or limited slip type, including a gear case ( 11 ) rotatably disposed within an outer housing (H) and means ( 37 ) to limit rotation of side gears ( 23,25 ) relative to the gear case ( 11 ), this means ( 37 ) including a member ( 41 ) which is axially moveable between a first position (FIG. 2 ) and a second position (FIG. 5 ). The mechanism includes a sensor assembly ( 95 ) and a sensor element ( 97 ) disposed adjacent the gear case ( 11 ). The axially moveable member ( 41 ) includes a sensed portion ( 89 ) surrounding an annular outer surface ( 11 S) of the gear case, and disposed between the annular outer surface ( 11 S) and the sensor element ( 97 ). Movement of the sensed portion ( 89 ) corresponding to changes within the mechanism between, for example, the unlocked and locked conditions, results in the sensor assembly ( 95 ) transmitting either a first or second electrical output. Thus, the present invention permits the vehicle control logic to know the condition of the differential mechanism and control certain other parts or functions of the vehicle accordingly.

What is claimed is:  
     
         1 . A differential gear mechanism including a gear case rotatably disposed within an outer housing and defining an axis of rotation, and a gear chamber; differential gearing disposed in said gear chamber including at least one input gear and first and second output gears; means operable to limit rotation of said first output gear relative to said gear case for common rotation therewith; actuation means for said rotation limiting means, said actuation means being operable in response to an input, to move said rotation limiting means from an unactuated condition to an actuated condition, said rotation limiting means including a member axially moveable between a first position corresponding to said unactuated condition of said rotation limiting means, and a second position corresponding to said actuated condition, characterized by: 
 (a) a sensor assembly being relatively fixed relative to said outer housing and including a sensor element disposed adjacent said gear case;    (b) said axially moveable member including a sensed portion which causes a first electrical output from said sensor element when said axially moveable member is in said first position and causes a second electrical output from said sensor element when said axially moveable member is in said second position.    
     
     
         2 . A differential gear mechanism as claimed in  claim 1 , characterized by said means operable to limit rotation of said first output gear relative to said gear case includes a plurality of lock members disposed within openings defined by said gear case, and axially moveable from an unlocked position to a locked position in engagement with mating openings defined by said first output gear.  
     
     
         3 . A differential gear mechanism as claimed in  claim 2 , characterized by said means operable to limit rotation of said first output gear relative to said gear case further including a plate-like member, said plurality of lock members being moveable with said plate-like member, and said plate-like member comprising part of said axially moveable member.  
     
     
         4 . A differential gear mechanism as claimed in  claim 1 , characterized by said gear case including a plurality of openings, said axially moveable member including a plurality of connector portions, each of said connector portions extending generally radially outward through said plurality of openings, said sensed portion of said axially moveable member being disposed external to said gear case and fixed to move axially with said plurality of connector portions, as said axially moveable member moves axially.  
     
     
         5 . A differential gear mechanism as claimed in  claim 4 , characterized by said sensed portion comprising a generally annular sensed member surrounding said gear case, and being closely spaced relative thereto, said sensor element being disposed immediately radially outward from at least a portion of said annular sensed member, when said axially movable member is in said second position.  
     
     
         6 . A differential gear mechanism as claimed in  claim 1 , characterized by a bracket member disposed adjacent said gear case and fixed relative to said outer housing, said bracket member including a sensor bracket portion disposed adjacent an annular outer surface of said gear case and operable to position said sensor element of said sensor assembly adjacent said sensed portion ( 81 , 89 ) of said axially moveable member.  
     
     
         7 . A differential gear mechanism as claimed in  claim 6 , characterized by said actuation means comprising an annular electromagnetic coil disposed axially adjacent said means operable to limit rotation of said first output gear, said bracket member including means operable to maintain said electromagnetic coil fixed relative to said outer housing and relatively fixed relative to said gear case.