To provide a power transmission device of four-wheel drive vehicle for obtaining optimum torque characteristics according to a driving state.
The power transmission device of a four-wheel drive vehicle comprises left and right vane pumps PL, PR connected to left and right rear wheels; an oilway for connecting a discharge port 37L of a left vane pump PL and a suction port 38; an oilway for connecting a discharge port 37R of a right vane pump PR and a suction port 38R; an oilway for connecting both the discharge ports 37L, 37R; and an oilway for connecting both the suction ports 38L, 38R. The power transmission device comprises a first bypass oilway that provides an orifice in the oilways and allows both the discharge ports to communicate each other without going through orifices OF5L, OF5R; a second bypass oilway for allowing both the suction ports to communicate each other without going through the orifices OF6L, OF6R; and first and bypass oilway opening adjusting valves 41, 45 that increase the opening of first and second bypass oilways according to a change in the rotational speed of a front wheel when the rotational speed of the front wheel increases and decrease the opening of first and second bypass oilways after a change in the rotational speed of the front wheel when the rotational speed of the front wheel decreases.
KUROKAWA TAKUYA
MIYATA KAZUNORI
