Patent GB-721262-A (GB)
Title: Improvements in or relating to balancing devices for the distribution of fuel to liquid fuel engines with multiple injection conduits
IPC: F02M69/50
Filed: 1952-12-03
Abstract: 721,262. Spray carburetters. SOC. DU CARBURATEUR ZENITH. Dec. 3, 1952 [Dec. 4, 1951], No. 30648/52. Class 7 (3). [Also in Groups XI, XXVI and XXIX] In a device for balancing the distribution of fuel from a supply manifold 1 to a plurality of conduits 3a...3c leading to injection nozzles situated in the intake pipes of a multicylinder engine, each conduit 3a...3c includes a metering restriction 6a...6c with a valve 9a...9c downstream thereof controlled by the pressure in the part 5a...5c of the conduit upstream thereof and by the pressure in a balance main 21 connected to the parts 5a...5c of the conduits through restrictions 23a...23c. Each valve, e.g. 9a, comprises a shuttle valve co-operating with a port 13a to control the fuel flow in its associated conduit 3a. At equilibrium the pressures in the chambers 17a, 18a, acting on the valve 9a are equal and, due to the balance main 21, are equal to the pressures at 17b, 18b and 17c, 18c. The valves 9a...9c thus maintain the pressures at 5a, 5b, 5c, and hence the pressure drop across the restrictions 6a...6c, equal so that the flows in the conduits 3a...3c are also maintained equal or in a predetermined ratio dependent upon the sizes of the restrictions 6a...6c In a modification the valves 9a...9c are arranged with their axes vertical to bias the valves towards their open position, equilibrium being established with one valve e.g. 9a in contact with its abutment 16a and a slightly higher pressure in its associated conduit 5a, so that a pressure intermediate that in the pipe 5a and the pipes 5b, 5c is set up in the balance main 21 and the resultant slight difference in pressure between the chambers 17b, 17c, and 18b, 18c opposes the weight of the valves 9b, 9c and holds them in an intermediate position. The difference in pressure between the pipe 5a and the pipes 5b, 5c, has a negligible effect on the flows in the pipes. Alternatively the valves may be arranged horizontally and biased towards the wide open position by arranging the pressure in the balance main 21 to be slightly below that transmitted to the chambers 17a, 17c. In Fig. 2 a throttle restriction 25 produces a pressure drop in each conduit 5 between the ends of the pipe 19 leading to its associated chamber 17 and the restricted pipe 22 leading to the main 21. Equilibrium is again established with one valve in its wide open position. The pipe 22 may alternatively open at the throat of a Venturi restriction in the pipe 5 which produces the lower pressure in the balance main 21, or the balance main 21 may be connected through a restriction to the conduit 3a at a point downstream of the valve 9a. The shuttle valves may be replaced by diaphragm operated valves and the fixed restrictions 6a...6c may be replaced by variable restrictions comprising slots 51a,... 51c, Fig. 7, in a spring loaded piston 54 actuated by the pressures upstream and downstream of the restrictions to maintain the pressure drop across them constant. The shuttle valves 9a... 9c of Fig. 1 may be replaced by hollow pistons having small orifices in the end face thereof which constitute the restrictions 23a...23c in the balance main 21. Specification 719,012 is referred to.