GB661308A - Improvements in and relating to electromagnetically controlled devices - Google Patents

Abstract

661,308. Valves controlled by auxiliary valves. UNITED AIRCRAFT PRODUCTS, Inc. April 22, 1949 [July 24, 1948] No. 10790/49. Class 135. [Also in Group XXXV] An electromagnet particularly of the type wherein a plunger has a relatively long travel, e.g. operating a valve or a switch, comprises a coil 38 within which reciprocate two axially aligned plungers 42, 43 separated by an air gap 44 which is maintained by a spring 32; but, when the coil 38 is energized, the spring pressure is overcome, the gap 44 closes, and the two plungers 42, 43 move together without being opposed by the spring 32. The figure shows an electromagnetically controlled valve to be inserted as a unit into a pump housing to which it is connected by threads 13. When the coil 38 is not energized, the plungers 42, 43 separated by the air gap 44 occupy the position shown, while the spring 32 pushes a rod 25 which passes through an opening 45 in the plunger 43. One end of the rod 25 abuts the plunger 42 and on the other end of this rod a needle valve 24 is formed. When the coil 38 is de-energized the needle valve 24 is open and relieves the fluid that might have passed in a chamber 23 from the pressure inlet 12 via a loose fit in the bore 11. Thus no pressure of the fluid is allowed to build up in the chamber 23 when the coil 38 is de-energized, otherwise the piston 14 is urged to open its valve 15 to the outlet port even against the main closing spring 17. When the coil 38 is energized, the plunger 42 moves first to close the gap 44, meanwhile the rod 25 is pushed by the plunger 42 and the valve 24 closes the relief fluid passage 21. The fluid pressure in the chamber 23 quickly rises and the piston assembly 20 moves leftwards to open the valve 15. Meanwhile the coil 38 remains energized and the plungers 42, 43 together with the spring 32 also move leftwards as a unit, thus leaving the valve 24 closed. When the coil 38 is de-energized, the spring 32 is effective to move the rod 25 towards the right and so opens the valve 24 with the result that the fluid pressure in the chamber 23 is relieved and the piston assembly 20 is returned in a direction to close the valve 15 by the spring 17.