GB1191641A - Improvements in Governors for Diesel Engines - Google Patents

Abstract

1,191,641. Diesel engine control computation. ROBERT BOSCH G.m.b.H. 19 May, 1967 [20 May, 1966], No. 23278/67. Heading G4G. [Also in Divisions F1, G1 and G3] To prevent excessive speeds and stalling of a diesel engine, the quantity of fuel injected per cycle into the engine, normally determined by accelerator pedal 36 (Fig. 1), is controlled at high and low engine speeds by the outputs from two non-linear circuits 45, 46 whose inputs are derived from a tachogenerator 10 driven by the engine. Under normal conditions i.e. those within the curve of Fig. 3 for which H represents the stroke of the injection pump and n the engine speed, solenoid 13, controlling the position of a rod 12 in the injection pump 11, is energized by the output of amplifier 24 fed with the voltage from the slider 37 of potentiometer 39 mechanically connected to pedal 36. Prevention of stalling.-When the engine is started, switch 77 is closed and at low engine speeds the voltage on the collector of transistor 73 of circuit 45 is higher than that on slider 37, diode 49 is conductive, supplying a relatively high voltage to amplifier 24 to adjust rod 12 to a position providing a large starting stroke H s . When the idling speed n1 is reached, switch 77 is opened by a centrifugal governor or electronically and the voltage supplied by circuit 45 is reduced, resulting in a decreased engine stroke H 1 , the diode 49 only remaining conductive while the voltage across transistor 73 is higher than that on slider 37. During the normal running of the engine, the diode 49 will become conductive at points along the curves 99, 100 (Fig. 3), dependant on the position of the pedal 36, to increase the injection stroke. Prevention of excessive speeds.-If a large stroke is requested by pedal 36 with a light engine load, the voltage at slider 37 is higher than that across transistor 55 of circuit 46, and diode 50 becomes conductive whereby, since circuit 46 has a low internal resistance compared with circuit 41, the input to the amplifier 24 is limited to the voltage across transistor 55. This voltage is arranged to vary as shown by curves 95, 96, 97 of Fig. 3 by the sequential change of state of diodes 67, 64, 60 with increase of voltage from the tachogenerator 10. The voltage at slider 37 may be made dependant on pedal position and also engine speed by circuit modifications (Figs. 4, 6, not shown).