GB622006A - Improvements relating to electromagnetically operated switches - Google Patents

Abstract

622,006. Electrically released switches. WILMOT-BREEDEN, Ltd., and STEPHENSON, C. H. Feb. 28, 1947, No. 5813. [Class 38(v)] An electrically-released switch is used to permit the operation of a fluid-pressure system, such as the window-operating mechanism of a vehicle, a predetermined number of times after the main switch of the vehicle has been opened. The electrically-released switch has a solenoid 19, which attracts a plunger 18 against the pressure of a spring 20 to bring the switch to its normal " on " position. The plunger 18 has ratchet teeth 21 which co-operate with a fixed pawl 22 and a spring-loaded pawl 23 carried by a plunger 24 which is moved against the pressure of a spring 25 by a further solenoid coil 27. A moving roller contact 12 mounted on the plunger 18 co-operates with a pair of relatively insulated fixed contacts 9, 10 and a spring- loaded contact 14. In the system shown, when the main switch in line 29 is open several operations of a motor under the control of a fluid pressure switch (not shown) will result in the repeated energization and de-energization of the coil 27, which, as coil 19 is not energized, permits the step-by-step downward movement of the spring-loaded plunger 18 as the pawl plunger 24 moves in and out. After the required number of operations of the motor, the roller 12 will have moved far enough for it to move suddenly from contact 9 to 10 due to the action of the V- shaped contact 14 on a spring-loaded " lostmotion" connection between the roller 12 and plunger 18. The motor circuit is now open, but the closure of the main switch causes the energization of coil 19 which retracts the plunger 18 fully to reset the mechanism.