Pressure Regulator Valve

Pressure Regulator Valve

Outline
^ The pressure regulator valve reduces oil pump discharge pressure and adjusts to the line pressure according to driving conditions.

Operation
^ See figure. Pressure regulator valve is pushed upward by spring force.

Before cutback (all ranges)
^ Spring force and pressure modifier pressure (7) are applied to the bottom end of the valve and push the valve upward. Conversely, oil pump discharge pressure (5) is applied to the top end of the valve and pushes the valve downward. Oil pump discharge pressure (5) is usually greater than spring force thus forcing the valve to move downward. When the valve moves downward, the drain port (X) will open and oil pump discharge pressure (5) will be reduced. Thus, oil pump discharge pressure (5) and spring force maintain the balance. Oil pump discharge pressure (5) is also called line pressure.

After cutback (forward drive range only)
^ Pilot pressure (17) is applied to the middle position of the valve and pushes the valve downward. Compared to before cutback, the force to push the valve downward is greater and oil pump discharge pressure (5) (line pressure) will be drained by the lower pressure. Specifically, line pressure (5) will adjust to the lower pressure. If, at this point, the accelerator is depressed, pressure modifier pressure (7) will pressurize. Pressure modifier pressure (7) pushes the valve upward and closes the drain port (X) of oil pump discharge pressure (5). This adjusts oil pump discharge pressure (line pressure) (5) to the higher pressure. Thus, line pressure (5) is adjusted according to pressure modifier pressure (7) and operates as each clutch and brake operation pressure.