Patent GB-1537363-A (GB)
Title: Fuel supply systems for heat generators
IPC: F02M69/20
Filed: 1976-03-11
Abstract: 1537363 Regulating IC engines SOC ANON AUTOMOBILES CITROEN 11 March 1976 [20 March 1975] 09873/76 Heading FIB [Also in Division F4] A fuel supply system for a heat generator e.g. an I.C. engine or a burner comprises a fuel spray tube 6, in an air inlet tube 2 and which is connected to the delivery line 9 of a pump 10 which delivers fuel at a greater rate than the fuel is consumed by the generator, the line 9 having, downstream of the connection to line 11, a variable-opening throttle valve 12 which is acted on by means C responsive to the rate of air-flow through inlet tube 2, line 9 extending to a constant-level chamber 35 into which excess fuel flows, the pump intake 10a being connected to chamber 35, the means C comprising a movable element 13 subject to a negative pressure produced by the air-flow through tube 2 and connecting means comprising tappet 21 between element 13 and valve 12 so that the fuel pressure in the line 9 which feeds the spray tube is under the control of the rate of air-flow to the generator, the system including a by-pass circuit controlled by a valve 47 which is upstream of the connection between lines 6 and 9 and which opens in response to a predetermined fuel pump delivery rate so that there is an exchange of fuel between the constantlevel chamber and the fuel tank 43 when the rate of generator fuel consumption is low. The piston element 13 in control means C defines a first chamber 14 subject to the depression which arises in Venturi 19 due to air-flow through tube 2. Duct 17 includes a surge tank 20. A second chamber 16 on the other side of element 13 is subject to the pressure in tube 2 upstream of a choke valve 5. Duct 22 includes a surge tank 23. The pressure difference across element 13 is modified by restricted communications P between ducts 17 and 22. A first inter-connecting duct 29 has a calibrated orifice 30 at one end and a checkvalve 31 at the other end which opens when the pressure difference exceeds a predetermined value. A second duct 32 connects duct 22 and the first duct 29 and includes calibrated orifice 33 and valve 34 which is linked to accelerator 4 and moves abruptly or progressively so that it is closed at full throttle. A third duct 25 is controlled by valve 26 which is actuated by barometric capsule 27 to open the valve as the pressure in volume 28 decreases. In chamber 35 a double valve-member 41a, 41b is actuated by float 37 so that pump 10 draws fuel from reservoir 43 when the level in chamber 35 drops below a predetermined level. Alternatively, chamber 35 is supplied with fuel directly from reservoir 43 by a separate pump, the double valve and pipe 42 being omitted. Upstream of the point where spray tube 6 connects to duct 9 is valve unit 47, divided into chambers 47a, 47b by movable partition 48, which is biased by spring 49 to close a relief duct leading to reservoir 43. A duct 52 including a calibrated orifice 53 permits fuel to flow to duct 9. Operation. At low-power operation of the engine, including starting, valves 31 and 34 are closed and the vacuum at Venturi 19 is applied, without modification, to piston element 13 which tends to close valve 12 so that a rich mixture is provided. As engine speed increases the vacuum at Venturi 19 increases, but valve 31 opens so that the pressure difference across piston element 13 is reduced, valve 12 is opened, fuel pressure in duct 9 decreases and the mixture strength is reduced. A further weakening of the mixture occurs when valve 34 is open. Valve 26 opens gradually as the pressure in duct 22 decreases resulting in progressive reduction in mixture strength. Capsule 27 may contain nitrogen so that it is sensitive to ambient temperature.