Patent GB-811788-A (GB)
Title: Electromagnetically actuated fluid-control valves
IPC: F16K31/40
Filed: 1955-12-20
Abstract: 811,788. Fluid-pressure brakes. NOVOTNY, B., KOCI, M., and ZAVODY V.I. LENINA NARODNI PODNIK. Dec. 20, 1955 [Dec. 20, 1954], No. 36526/55. Class 103 (1). [Also in Group XXIX] In an electromagnetically-actuated fluid control valve for a vehicle braking system, air from a container, not shown, which enters a space A, Fig. 1, between two double-conical valve closures 20 and 26 lifts the small closure 20 so that its upper cone shuts a discharge port 17 in a pilot piston 15 connected to a spring-loaded solenoid armature 9 whereupon air from the space A flows past the lower cone of the closure 20 through a channel C to lift a control piston 24. Air pressure below the pilot piston 15 opposes the weight of the latter as well as that of the moving parts of the solenoid, the force of the solenoid spring and the thrust of the energized solenoid. As the pressure beneath the pilot piston 15 increases the latter is elevated until the lower cone of the closure 20 engages its seat in a housing 18 thereby preventing the admission of further air beneath the control piston 24 so that the forces acting on the pilot piston are in equilibrium. Any increase in the solenoid current, which is regulated by a series resistor, presses the pilot piston 15 downwards and air from the container again passes the lower cone of the closure 20 into the spaces beneath the pilot and control pistons until equilibrium is re-established. A similar but opposite action also leads to an equilibrium condition when the solenoid current is reduced. At a given position of the control piston 24 the lower cone of the large closure 26 closes a discharge port 30 through the piston stem but upon a given high pressure being attained the piston 24 is raised and unseats the upper cone of the closure 26 so that air from the space A flows into the space E above the piston 24, which space is connected to the brake cylinder, not shown, of an electric locomotive, for example. Any pressure increase in the space E lowers the piston 24 until the upper cone of the closure 26 seats and prevents further admission of air to the brake cylinder whereupon the forces acting on the control piston are in equilibrium. Any increase or decrease in the pressure beneath the control piston causes air to be admitted to or discharged from the space E until equilibrium is restored. In a modification, the armature is lifted against the action of a spring so that upon the solenoid being energized the brake cylinders are discharged whilst when the solenoid current is interrupted the cylinders are charged; the valve may be actuated by manual compression of the spring. With such an arrangement it is possible to obtain a continuous transition from electric to pneumatic braking. The solenoid coil may be energized from a battery or the brake circuit of the locomotive driving motors. In another modification, an additional cylinder 45, Fig. 3, is attached to the main valve housing in which is a piston 48 having a stem 43 that seats against the depending stem of the control piston 24; the stem 43 does not prevent air being discharged through ports 30, 42, which latter is located in the cylinder 45. The cylinder 45 has an air inlet 50 connected with the brake cylinders of a hauling vehicle the air from which raises the piston 48 and hence piston 24; when the discharge through the port 30 is stopped by the valve 26, Fig. 1, the latter is raised admitting air to the brake cylinders of the hauled vehicle. When the pressures on the pistons 24, 48 are equal the valve 26 shuts off air supply to the brake cylinders. By connecting the space beneath the piston 48 with an additional air source or by locating a spring beneath this piston and connecting the space above it with the train pipeline the valve can be controlled by reducing or increasing the pipeline pressure. Each solenoid may comprise two differential coils, one permanently fed from a battery and the other in circuit with the brake circuit of a driving motor.