Viscous fan drive systems with fan drive slip feedback

Abstract

A viscous fan drive which includes a moveable component in the scavenge or fill passageway that moves relative to pressure that is proportional to slip speed. The force which moves the component into and out of the passageway is directly proportional to the slip speed of the fan drive. This balances the fill and scavenge flow.

What is claimed is: 
     
         1 . A viscous fluid coupling assembly for a fan member comprising:
 an output member including a center shaft and configured for attachment to a fan member;   an input member bearing mounted to said output member and rotatable relative to said output member and at input speed;   a viscous fluid supply mechanism positioned within said input member and comprising a rotor member, a reservoir plate member having a fluid aperture, a fluid reservoir, a scavenge passage, a wiper, a working chamber and a quantity of viscous fluid;   a valve mechanism for controlling viscous fluid engagement of said output member with said input member, said valve mechanism having a moveable member for opening, partially opening and covering said fluid aperture; and   a moveable member positioned in operative association with said scavenge passage;   said moveable member being moveable into and out of said scavenge passage and being able to alter the flow of viscous fluid in said scavenge passage;   said moveable member being moveable relative to pressure that is proportional to slip speed.   
     
     
         2 . The viscous fluid coupling assembly of  claim 1  further comprising an electronic control for controlling the movement of said valve mechanism. 
     
     
         3 . The viscous fluid coupling assembly of  claim 1  wherein said output member comprises a housing and said input member comprising a body member and a cover member. 
     
     
         4 . The viscous fluid coupling assembly of  claim 3  wherein said input member is positioned around said output member and rotates at input speed. 
     
     
         5 . The viscous fluid coupling assembly of  claim 1  wherein said moveable member is moveable into said scavenge passage through an opening in said passage. 
     
     
         6 . The viscous fluid coupling assembly of  claim 5  further comprising a biasing member biasing said moveable member away from entering said scavenge passage. 
     
     
         7 . The viscous fluid coupling assembly of  claim 1  further comprising a secondary passageway which is in fluid communication with said scavenge passageway and which applies fluid pressure to said moveable member. 
     
     
         8 . A viscous fluid coupling assembly for a fan member comprising:
 an output member including a center shaft and configured for attachment to a fan member;   an input member bearing mounted to said output member and rotatable relative to said output member and at input speed;   a viscous fluid supply mechanism positioned within said input member and comprising a rotor member, a reservoir plate member having a fluid aperature, a fluid reservoir, a scavenge passage, a fill passage, a wiper, a working chamber and a quantity of viscous fluid;   a valve mechanism for controlling viscous fluid engagement of said output member with said input member, said valve mechanism having a moveable member for opening, partially opening and covering said fluid aperature; and   a moveable member positioned in operative association with said fill passage;   said moveable member being moveable into and out of said fill passage and being able to alter the flow of viscous fluid in said fill passage;   said moveable member being moveable relative to pressure that is proportional to slip speed.   
     
     
         9 . The viscous fluid coupling assembly of  claim 1  wherein said moveable member is moveable into said fill passage through an opening in said passage. 
     
     
         10 . The viscous fluid coupling assembly of  claim 9  further comprising a biasing member biasing said moveable member away from entering said fill passage. 
     
     
         11 . The viscous fluid coupling assembly of  claim 1  further comprising a secondary passageway which is in fluid communication with said fill passageway and which applies fluid pressure to said moveable member.