IMPROVEMENTS IN AND RELATING TO FUEL INJECTION GOVERNORS FOR DIESEL INTERNAL COMBUSTION ENGINES AND PARTICULARLY TO ELECTRICAL PROTECTION CIRCUITS FOR SUCH GOVERNORS

摘要

1,273,107. Fuel injection system. ROBERT BOSCH G.m.b.H. Dec. 11, 1970 [Dec. 13, 1969; Aug.29, 1970], No.58844/70. Heading G1N. In a Diesel I.C. engine fuel injection control system, a switching device 25 is provided for controlling a fuel-flow adjusting unit 12 to give an excess quantity of fuel during starting, an overspeed switching device is provided to cut-off fuel supply when overspeed is sensed, and an auxiliary rectifier 42 driven by pulses of frequency dependent upon engine speed to produce a negative D.C. voltage proportional to engine speed, is provided, the device 28 being triggered to cut-off excess fuel by a signal comprising the combination of the negative D.C. voltage and a positive D.C. voltage inversely proportional to engine speed, and the device 26 being triggered upon overspeed by a signal comprising the combination of the negative D.C. voltage and a positive voltage produced above a pre-set frequency by a frequency rectifier 49 which is driven by the speed dependent pulses. As shown, under normal operating conditions the fuel-flow adjusting device 12 is controlled by a signal produced by the output of a function generator 18 in dependence upon signals representing the throttle position 19 and engine speed, the output being modified by the signal from a position transducer 13. The speed signal is derived from a transducer 14 which provided pulses of frequency proportional to engine speed, the pulses being applied to an amplifier 15 and a switching device 16 whose output is applied to a filter 17 to provide the positive D.C. voltage inversely proportional to engine speed. When the circuitry is switched on devices 25 and 26 are operated to energize their relays S, œ which cause their switches s, and ³1 and ³2 to change over, a lamp 62 then being lit to indicate that overspeed device 26 is functioning. When the engine is started, the relay œ is de-energized but the relay S is maintained energized to thereby connected the terminal 61 of the fuel device 12 to earth and apply the full operating voltage to device 12 to provide maximum fuel injection. When the engine speed reaches a pre-set level due to excess fuel, the device 25 is triggered to de-energize relay S so that terminals 60, 61 are connected between +U b and the output of generator 18. When a pre-set engine speed is exceeded, the device 26 is triggered to energize relay œ and cut-off terminals 60, 61 from the voltage. In a modification, Fig. 2 (not shown), the speed value at which the device 26 is triggered is made variable in dependence upon engine loading such that fuel is not cut-off when the engine acts as a brake.