GB1451612A - Diesel internal combustion engines - Google Patents

Abstract

1451612 Automatic control ROBERT BOSCH GmbH 9 Nov 1973 [13 Nov 1972] 52124/73 Heading G3N A diesel internal combustion engine has an electrically controlled injection system incorporating electromagnetically operable injection devices controlled by a transistorized switching device. As shown, pulses from a cam-shaft tachogenerator 1 are fed to a D-to-A converter and the derived voltage together with a command variable, desired speed or butterfly valve angle, processed in a regulator 3 to provide a voltage Ti proportional to the filling time of a solenoid operated injection device 9. The pulses are also applied to a converter 4 providing a voltage Tl proportional to pulse period. The filling time voltage Ti is subtracted from the period voltage Tl in a subtractor 5 and the difference compared with a ramp voltage generated by a constant-current device 6 initiated by a switch S actuated at each rotation of the engine. At equality a bi-stable circuit 8 is set to initiate a control pulse to the solenoid of the valve 9. The control pulse is terminated by the circuit 8 being reset by the next actuation of switch S1. In an alternative arrangement the ramp voltage is derived from a D/A converter responsive to the contents of a counter connected to receive the tachogenerator pulses when initiated by the switch Sl. The control circuitry is embodied by discrete transistors in combination with integrated circuits. The solenoid-operated valve 9 opens a fuel line, the flow from which pushes back a piston of an injection cylinder. When de-energized, after the induction of a desired quantity of fuel, the valve switches over to admit the fuel to a servopiston coaxial with the injection piston whereby the fuel is injected into the engine.