Patent GB-896976-A (GB)
Title: Methods of and apparatus for controlling the supply of fuel and air to internal combustion engines
Inventor: LYON GERARD ANTHONY
IPC: F02M69/00
Filed: 1959-11-16
Abstract: 896,976. Carburetting apparatus. ENGINEERING RESEARCH & APPLICATION Ltd Nov. 14, 1960 [Nov. 16, 1959], No. 38749/59. Class 7(3). A method of controlling the supply of fuel and air to an internal-combustion engine comprises pumping fuel to an outlet chamber or supply column, exhausting the chamber or column at a rate variable in relation to movements of a driver operated accelerator element, supplying fuel from the chamber or column to at least one fuel injection nozzle or discharge orifice, controlling the supply of air to the engine in proportion to the fuel supplied, deriving forces proportional to the fuel pressure and the rate of flow of air respectively and increasing and decreasing the rate of air flow when one of the forces is greater and less respectively than will balance the other and further exhausting the column at substantially full throttle opening. In Fig. 1 movement of the accelerator pedal opens or closes fuel control valve 11. Closure of this valve restricts the discharge of fuel to the chamber 4 and consequently raises the pressure in channels 8, 9, 10, 16 and chamber 12 and increases the fuel flow through the nozzles to the engine. Increased pressure acts on piston 17 moving it in an upward direction thus moving roller 18, levers 19, 20, throttle rod 21 and lever 23 in such a direction as to open the butterfly valve 22, and thus increasing the air flow through the Venturi 30. This movement continues until the increased air flow which in turn increases the depression in the Venturi 30 is sufficient to provide sufficient balancing force in the throttle rod 21. This balancing force is provided by the depression in Venturi 30 when balance is obtained the piston 17 ceases to move and the system remains in equilibrium. The port 15 is so placed in the wall of the spill valve chamber 12 that it is opened by movement of the piston 17 when the butterfly valve 22 attains the fully open condition. Additional fuel greater than that required to maintain a balance of force between the Venturi diaphragm device 28 and the piston 17 is thus discharged from this port to the chamber 4. Fig. 2 shows a servo device suitable for use with the arrangement of Fig. 1. Channels 50, 51 are jointly connected by a flexible pipe 49 to a suitable vacuum source for example the inlet manifold of the engine. In the modification of Fig. 3 the servo devices 26, 27 are acted on by the fuel pressure instead of the external source of air pressure. Starting is readily performed by the use of the well known strangler valve so positioned as to close or partially close pipe 130 on the atmospheric side of Venturi 30. It is also well known to provide an adjustable orifice (or orifices) on the engine side of the butterfly 22. This may be connected via suitably sized atmospheric bleeds to the Venturi diaphragm device 28 thus providing a variable degree of enrichment according to the manifold depression and disposition of the orifice separate control of the fuel under idling conditions can be obtained by the device shown in Fig. 4. According to this device fuel discharging from 11, 11a and 14 passes into a cylindrical chamber 80 in housing 5 fitted with plunger 81 loaded adjustably by a spring 82. The compression of spring 82 ensures a constant discharge pressure under idling conditions. Complete cut-off of fuel under over-run conditions and/or an alternative method of obtaining enrichened mixture for starting may be provided by means of a two-direction electromagnetic device (not shown) which provides complete retraction of 80 and/or complete closure of port 85 respectively. Modification of the mixture strength may be carried out by an auxiliary diaphragm connected by a lever to the throttle rod 21. The float operated valve may be replaced by a diaphragm operated valve.