Patent ID: 7578376

Claim:
A vehicle transmission comprising: a controllable hydraulic pump operable for generating a line pressure; a latched-pump applied clutch (LPAC) circuit including: a clutch in fluid communication with said hydraulic pump, said clutch including: a clutch cylinder having a variable clutch-apply pressure; and a clutch-apply piston disposed within said clutch cylinder; an accumulator in fluid communication with said hydraulic pump and said clutch-apply piston, said accumulator containing an accumulator piston and being operable for accumulating a boost pressure as a compressive force acting on a first side of said accumulator piston, and for selectively transmitting said boost pressure to said clutch from a second side of said accumulator piston that is opposite said first side to temporarily increase said variable clutch-apply pressure in response to predetermined conditions; and a plurality of valves including a first valve in fluid communication with each of said hydraulic pump and said accumulator at said first side of said accumulator piston for selectively admitting said boost pressure into said accumulator, and with said clutch at said second side of said accumulator piston, and a second valve in fluid communication with each of said hydraulic pump and said clutch-apply piston and positioned therebetween for admitting said pressurized fluid into said clutch cylinder to thereby provide at least part of said variable clutch-apply pressure; wherein the selective transmission of said boost pressure to said clutch-apply piston temporarily increases said variable clutch-apply pressure by boosting said line pressure, and wherein said first valve opens when said clutch is in one of a fully engaged state and a disengaging state, and wherein said second valve opens when said clutch is in one of an engaging state and a disengaging state, both of said first and said second valves otherwise remaining closed.