GB1417703A - Fuel injection apparatus for internal combustion engines - Google Patents

Abstract

1417703 Regulating fuel injection; spray carburetters; fuel pumps G K N TRANSMISSIONS Ltd 27 Feb 1973 [3 March 1972] 9943/72 Heading FIB Fuel injection apparatus includes a carburetter having an air inlet (101a), Fig. 4 (not shown) of smaller cross-sectional area than that of an inlet duct 34, Fig. 2 downstream of throttle 36, a fuel jet element 103, Fig. 3 and air cut-off and fuel cutoff valves (101, Fig. 4), 116 which are closed by fuel pump pressure. The fuel injection apparatus comprises the air inlet duct 34, a fuel pump 18 delivering to fuel injectors (26), Fig. 1 (not shown) metering means (20) driven by the engine for delivering measured fuel quantities in each operation cycle and sensing means sensing operating parameters and thereby controlling operation of the metering means. The fuel supply system includes a low-pressure pump (13, Fig. 1) drawing fuel through a filter 12 and delivering to the high-pressure rotary vane pump 18 which supplies fuel e.g. petrol through a commutating and distributing valve 19 which operates a metering shuttle piston 20a, and also distributes the fuel successively to the fuel injectors (27). Excess fuel is returned through a blow-off valve 31, Fig 3 to pipe (32, Fig 1). The stroke of piston 20a between stops 20b, 20c is controlled by sensing means 29 which includes a bellows 29a to sense pressure in air inlet 34. Inlet air temperature is sensed by wax capsule element 34 and engine coolant temperature is sensed by element 38, the axial displacements of the elements being added by a mechanism 39 which has a rotary output element 40 to which bellows 29a is fixed. The other end of bellows 29a carries a frusto-conical cam element 41 which is displaced axially in dependence on inlet pressure and rotated in dependance on air or coolant temperature to adjust the position of the lower stop 20c. A sudden increase in inlet pressure due to sudden opening of the throttle valve 36 causes an accelerator piston 50 to displace the bellows and cam to the right to produce a short-term mixture enrichment. The carburetter 30 operates only during starting. Low-pressure fuel is fed via inlet 14a, Fig 2 to passage 136, Fig. 3 and thence flows via threshold valve 108, passage 105, chamber 119 and orifices 116 to mix with air in bore 101, the mixture passing via duct 101b into inlet 34. When the high-pressure pump 18 supplies sufficient pressure piston 117 is moved upwardly to close the fuel and air orifices 116, (101), Fig 4 (not shown).