GB1365270A - Fuel injection systems - Google Patents

Abstract

1365270 Spray carburetters ROBERT BOSCH GmbH 5 July 1972 [5 July 1971] 31347/72 Addition to 1283860 Heading F1B A fuel injection system for mixture compressing I.C. engines having continuous injection into the intake manifold and separate ignition as claimed in Claim 1 of Specification 1283860 is modified in that the return force is provided by hydraulic pressure which is determined by a spring in a pressure regulating valve, the prestress of the spring being variable by means of the electromagnet. This flow into the intake manifold 1, 4, 5 moves the measuring element 2 about its pivot 9 and hence the fuel distributing valve spool 11. Fuel from the feed line 18 is tapped off by a branch pipe 32 via a throttle 34 and a further throttle 57 and enters a chamber 33 where it acts on the end surface 12 of the spool. A passage 35 leads from the space between the two throttles to a diaphragm type pressure regulating valve 36. The valve comprises a diaphragm 24 and a valve seat 40, movement of the diaphragm away from the seat creating an annular cross-section for fuel flow to a pipe 37 which leads back to the fuel tank 17. The diaphragm is pressed against the seat by a spring 43, which abuts an adjusting screw 44 and is contained within a core 46 which carries a coil 51. Interposed between the diaphragm and the spring is an armature 47 which is carried by a spider support 52. A ring 56 closes the magnetic circuit. Current fed to the coil 51 creates a magnetic field which opposes the spring force, reduces the pressure in chamber 33 and results in enrichment of the fuel/air mixture supplied to the engine. The current supplied to the coil through the socket 55 is varied in accordance with the angular position of the throttle valve, to the shaft of which is attached a slider 65. The slider engages a series of segments which through resistors 70, 71, 72 vary the potential on the base of an emitter-follower connected transistor 77 controlling the current flow through the coil 51. The resistor 70 is variable and enables the idling mixture to be adjusted. An NTC resistor 73 enriches the mixture when the engine is cold. A signal U ST corresponding to other engine characteristics or to atmospheric pressure for altitude correction may be added. An RC circuit in series with a resistor 63 enriches the fuel-air mixture during starting and the first twenty seconds of running.