Electromagnetic control valve for a pressure fluid and associated method

Claim 1

An electromagnetic control valve for controlling the flow of pressure from a pressure chamber in which a pressure is established and controlled as a function of an electric voltage applied to an excitation coil, said valve comprising a valve body controlling fluid flow and movable between open and closed positions, a magnetic circuit having an air gap and including an excitation coil energizable by a voltage to produce an electromagnetic force which acts on said valve body to urge the same to the closed position, a pressure chamber for a pressure fluid acting on said valve body with a force to urge the same to the open position, the electromagnetic force being variable as a function of the voltage and having a value greater than the force of the pressure fluid in the closed position of the valve, and adjustable means for adjusting the size of said air gap to regulate the magnitude of the electromagnetic force acting on the valve body in closed position whereby to minimize the size of the valve and eliminate the need for a biassing spring, said magnetic circuit comprising a body of magnetic material, said adjustable means comprising a non-magnetic element displaceably supported in said body and projecting therefrom by a distance forming said air gap, said non-magnetic element facing said valve body and forming a seat therefor, said valve body being made of a magnetic material and forming an armature in said magnetic circuit which is attracted towards said seat by said electromagnetic force, said body of magnetic material including a spindle supporting said non-magnetic element and focussing magnetic lines of force therein, said valve body comprising a ball, said non-magnetic element being a tubular body facing said ball, said spindle having an annular groove in which said tubular body is displaceably inserted to a frictionally secured position.