The valve has a body (2) defining a chamber (3) and having an inlet orifice (5) and an outlet orifice (6) at the chamber. A closer (23) partially closes the orifice (5). A plate spring (26) maintains the closer against the orifice (5) to regulate the passage of liquid by the inlet orifice. A rotor (4) has a cam forming surface (20) on which the spring is supported by forming a movable contact with the surface.
