Patent ID: 8414452

Claim:
A power transmission device that is installed in a vehicle and that is connected to a power generation source that is capable of outputting power for driving, the power transmission device comprising: a belt-type continuously variable transmission that includes a first pulley provided on a drive side rotating shaft, a second pulley provided on a driven side rotating shaft, a belt that runs between the first pulley and the second pulley, a first fluid pressure cylinder that can vary a groove width in the first pulley, and a second fluid pressure cylinder that can vary a groove width in the second pulley, and that is capable of continuously varying power that is transmitted from the power generation source to the drive side rotating shaft by varying the groove widths in the first and the second pulleys using the first and the second fluid pressure cylinders and outputting the power to the driven side rotating shaft; a working fluid accumulation portion that accumulates a working fluid; a friction engagement element that is capable of transmitting the power from the power generation source to the drive side rotating shaft when the working fluid is supplied to the friction engagement element; a first pump that is driven by the power generation source and that is capable of taking in the working fluid from the working fluid accumulation portion and discharging the working fluid; a pressure regulating valve that is capable of regulating the pressure of the working fluid from the first pump and outputting the working fluid to the first and the second fluid pressure cylinders; a friction engagement element pressure regulating valve that is capable of regulating the pressure of the working fluid from the first pump side and outputting the working fluid to the friction engagement element side; a second pump that is driven by electric power and that is capable of taking in the working fluid from the working fluid accumulation portion and discharging the working fluid; and a switching valve that is capable of supplying the working fluid from the friction engagement element pressure regulating valve to the friction engagement element when the working fluid is discharged from the first pump and that is capable of supplying the working fluid from the second pump to the friction engagement element when the working fluid is not discharged from the first pump.