Abstract: An electromagnetic valve with servo-control is controlled by a movable core. The fluid under pressure contained in the chamber for the servo-control passes by a stationary seat capable of being closed by a flap valve on the core. The seat is fed by fluid under pressure through a conduit in a movable valve through a sliding tube. This tube can be made of plastic material and be reinforced by an externally mounted spring.

Abstract: Control system for an electromagnet having a movable core, wherein a power winding is provided for moving the core to active position and a holding winding requiring less power maintains the core in active position. A transistor controls the power supply circuit and, when made conductive, energizes a transistor in series with each winding, thus energizing both windings. After a time delay provided by a resistor-condenser circuit, another transistor is energized which causes the transistor in the power winding to become non-conductive, thus de-energizing the power winding. De-energizing the control transistor causes the transistor in the maintenance winding to become non-conductive so that the maintenance winding is de-energized and its energy is dissipated through a Zener diode and a resistor, both in series therewith.

Abstract: A servo-controlled valve comprises two valve clacks cooperating with respective seats and mounted on a rod axially movable between two stable positions. Movement of the rod from one stable position to the other is actuated by supplying fluid under pressure to a respective servo-control chamber. When the rod reaches an intermediate unstable position, past which its movement is sustained, the rod actuates opening of an emptying orifice to evacuate the chamber filled with fluid under pressure.

Abstract: A two-way valve has a valve clack cooperating with a seat and mounted with play in a mobile core of an electromagnetic actuator to provide fluid-assisted opening of the valve. The mobile core moves in a chamber connected to the fluid inlet by a restricted annular passage disposed about the core. Movement of the mobile core towards the open position produces an increase in the cross-sectional area of the restricted passage, so that the fluid assistance is initially great, but then decreases.

Abstract: A fluid-assisted electromagnetic valve comprises an element movable in a working chamber as a function of a fluid pressure differential applied by an electromagnetic control. The movable element has inlet and exhaust nozzles in the working chamber which are selectively obturated by respective spring-biased plungers mounted on an extension of a mobile core of the electromagnetic control, according to the direction of movement of the core, to provide the pressure differential. Said extension comes to bear directly against the respective nozzle to ensure movement of the element even when the pressure differential is insufficient.

Abstract: An electromagnetic actuator having a plunger core and a stationary ferromagnetic core, both surrounded by an electrical winding, is provided with means for adjusting the axial position of the stationary core in relation to the winding, said means being operable from outside the actuator.