GB1298763A - Fuel injection system for an internal combustion engine - Google Patents

Abstract

1298763 Fuel injection control PHYSICS INTERNATIONAL CO 6 Feb 1970 [6 Feb 1969] 5917/70 Heading G1N In a diesel engine fuel injection control system, a small quantity of fuel is injected into each cylinder a variable period, determined by engine speed, before the main injection of fuel into each cylinder, the main injection occurring at a fixed crank angle. As shown, the engine rotates a cam 30 which operates three switches 32, 34, 35. Upon closure of switch 32, a ramp generator 42 generates a voltage V 1 which maintains a value V 2 when the main switch 34 is closed, the voltage V 2 being held by a circuit 50 after a delay. Closure of the switch 34 also applies a pulse through a starter switch 66 to an amplifier 68, an electronic switch 102, and a main pulse width control 104. Operation of switch 102 allows a main injection power supply 100, adjusted by an operator's control 109 and a control and governer circuit 108, Fig.3 (not shown), to energize an electro-expansive pump 82 for a cylinder for a duration determined by the main pulse width control 104. Circuits are reset by the switch 35 and on the next cycle closure of switch 32 again starts generators 42 and 44. The voltage V 2 held in 50 during the previous cycle has subtracted from it a voltage V 3 representative of engine parameters, e.g. temperature, octane number, to provide a voltage V 4 which is compared at 62 with the voltage V 5 of the generator 44. When the voltages V 4 and V 5 become equal a pulse is produced which is applied, via a switch 90, to an electronic switch 92 and a pilot pulse width control 94. Operation of the switch 92 allows a pilot power supply 84 to energize the electroexpansive pump 82 for a duration set by the control 94. Main injection then follows when switch 34 is closed. The pilot power supply 84 may be adjusted by engine parameters. During starting the switch 90 is opened to prevent pilot injection, and the switch 66 is operated to delay the main injection for a period depending on engine temperature. One such system described is provided for each engine cylinder. In a modification for a four cylinder engine, Fig.4 (not shown), four main switches 34a-34d and four main pulse shaping circuits 46a-46d are provided, one for each cylinder, each switch forming the start and reset switch for a succeeding and preceding main switch respectively. In a further modification for a four cylinder engine, Fig.5 (not shown), again four main switches and four main pulse shaping circuits are provided, the outputs of the pulse shaping circuits (146a-146d) being applied both to the main injector control and to an OR gate (149) which is connected to a ramp generator (152) and sample and hold circuit (150) for providing the voltage V 2 . The switches are connected to respective AND gates (148a-148d), the other inputs of the AND gate being connected to the output of the comparator of the voltages V 4 and V 5 . The output of each AND gate is connected to a respective pilot control.