Hydraulically actuated plate clutch with accumulator

Claim 1

Control means for hydraulically actuating a plate clutch having at least one first clutch plate and at least one second clutch plate and a piston means for moving said first plate in a first direction into engagement with said second plate, said control means comprising: means under stress and operatively connected to said piston means for resiliently biasing said piston means in a second direction opposite to said first direction and for normally holding said first plate out of engagement with said second plate, whereby when said piston means moves in said first direction said biasing means becomes increasingly stressed, a source of fluid, first conduit means in fluid communication with said piston means for transmitting fluid under pressure from said source to said piston means to move said piston means in said first direction, thereby increasingly to stress said biasing means, a pump in said first conduit means between said source and said piston means for supplying fluid under pressure to said piston means, first valve means in said first conduit means for interconnecting said pump with said piston means through said first conduit means in a first position of said first valve means and bypassing said pump and interconnecting said piston means with said source in a second position of said first valve means, a fluid accumulator, second conduit means for selectively interconnecting said accumulator with said first conduit means, automatically openable second valve means disposed in said second conduit means, means biasing said second valve means to remain in a closed condition until after said piston means have moved a preselected distance in said first direction and said means resiliently biasing said piston means has thereby become stressed a preselected amount, said second valve means being responsive to pressure build up resulting from stressing said means biasing said piston means to only then place said accumulator in communication with said first conduit means to receive part of the fluid which would otherwise by transmitted to said piston means, thereby to decrease the rate of movement of said piston means in said first direction, third conduit means connected between said accumulator and said first conduit means, one way valve means in said third conduit means, fluid pressure in the portion of said third conduit means between said one way valve means and said first conduit means maintaining said one way valve means closed while said first control valve means is in said first position and until said first control valve means is moved to said second position at which time fluid pressure in the portion of said third conduit means between said accumulator and said one way valve means exceeds the fluid pressure in the portion of said third conduit means Between said first conduit means and said accumulator at which time said one way valve means opens and said accumulator discharges fluid into said first conduit means for flow of fluid to said source, whereby said piston means moves at a first faster rate during the first portion of its movement in said first direction and at a second slower rate during the second portion of its movement in said first direction after said second valve means has opened to establish communication with said accumulator.