GB711749A - Improvements in control systems for internal combustion engines - Google Patents

Abstract

711,749. Engine stop-gear. CARTER CARBURETOR CORPORATION. April 25, 1952, No. 10513/52. Class 122(4) [Also in Group XXVII] A protective control system for a pressure lubricated internal combustion engine comprises an electrically driven fuel pump 10, an electrical system including a starter motor 22 and. switch 28 therefor and a battery 23 connected through an ignition switch 47 and two parallel circuits to the fuel pump 10, a control switch 76 in one circuit that closes and energizes the fuel pump when the starter switch 28 is closed, a second control switch 42 in the second circuit actuated by the engine lubrication pressure and closed when that pressure is normal, a resistance circuit in parallel with the second circuit and including an indicator device 70 that has a resistance sufficient to reduce the voltage across the fuel pump to less than that necessary to actuate it, and operates when an abnormal fall of lubrication pressure causes the switch 42 to open and break the second circuit and also when the ignition switch is closed prior to engine starting. The switch 42 comprises a casing divided into a pressure chamber 55 and a switch chamber 56 by a diaphragm 54 carrying a spring-loaded plunger 60 having an insulated tappet 63 thereon caused by lubrication pressure below the diaphragm 54 to press against a spring arm 43 and close contacts 40. 59. The indicator device is shown as a lamp 70 but may be a bell or buzzer. When the engine is not in operation the switches are in the open positions shown. Upon closure of the ignition switch 47 current flows from the battery 23 through the lamp 70 and the fuel pump 10 to earth at 36 but the pump does not operate due to the current limiting effect of the lamp. The engine is started by closing the starter'switch 28 which, in addition to energizing the starter motor 22, energizes and closes the switch 76 to short circuit the lamp 70 and connect the battery direct to the fuel pump which then operates to supply fuel to the carburetter. When the engine starts the starter switch is released and the switch 76 de-energized and opened but lubricant pressure from the oil pump 15 acting beneath the diaphragm 54 closes the switch 42 and current still flows direct from the battery to the fuel pump via the switch 42, the lamp 70 again being shortcircuited. If during engine running the lubrication pressure falls below the allowable minimum the plunger 60 is retracted by its spring 64, the switch 42 is opened and the circuit to the fuel pump includes the lamp 70 which affords a visual warning and reduces the current to the pump so that the latter stops and the engine comes to rest. Specification 631,283, [Group XXVII], is referred to.