Patent GB-614910-A (GB)
Title: Improvements in or relating to internal combustion engine carburetors
IPC: F02D9/00
Filed: 1944-12-21
Abstract: 614,910. Spray carburetters. MARCO, L. DE. Dec. 21, 1944, No. 25651. Convention date, Sept. 27, 1943. [Class 7 (iii)] A manual control member is operatively connected to one of two air valves for controlling the volume of fuel air mixture fed to an engine, a governor controlled automatic member is operatively connected to a fuel valve and to the other of the air valves for further controlling the air supply and also the fuel supply and mechanism interconnects the manually controlled air valve and the fuel valve for predetermining the fuel air ratio at a desired setting of the air valve. As shown fuel is supplied to an induction passage 10 through a nozzle 43 having a needle valve 42 which controls the flow of fuel into the passage. Primary air is controlled by two butterfly valves 12, 13 in the passage. Operation of the butterfly valve 12 is by hand through a link 16 and operation of the butterfly valve 13 is by a governor driven by the engine and connected to the valve by a link 25, levers 24, 22 and a roller 20 carried by an arm 19 secured to the valve shaft 18. The hand-operated butterfly valve 12 by means of an arm 34 and link 32 operates a slotted cam member 31 which is free to rotate on the shaft 18 of the governor operated butterfly valve. Movement of the cam member in an anti-clockwise direction operates the fuel needle valve 42 by means of a shoulder 37 in the slot 35, 36 the shoulder acting on a roller 30 connected to a slide member 27 linked to the needle valve operating mechanism. The initial movement operates the needle valve and further opening of the butterfly valve does not affect the needle valve since portion 35 of the slot is concentric with the point of rotation. This enables the mixture to be enriched on the initial opening of the butterfly valve 12 when it is desired to accelerate the engine. The portion 36 of the slot comes into operation during closing movement of the hand-operated butterfly valve. The governor-controlled butterfly valve is also interconnected with the fuel valve by means of the slide member 27 which slides in a block 26 attached to the butterfly valve shaft 18 and carries at its upper end a further slot 28 co-operating with a roller 29. An increase of speed of the engine causes the governor to open the butterfly valve 13 and at the same time increase the opening of the fuel valve 32 by means of the slot 28 which moves the roller connected to the fuel valve operating lever. A further hand control is provided by means of which the fuel needle valve can be opened independently. This control operates through a rack 54 which raises a plunger 50 on the end of which the operating lever 46 of the valve is mounted. An altitude control is also provided which by means of a helically slotted member 66 carried on the plunger varies the effective length of the plunger according to changes of altitude and thereby the setting of the needle valve will be varied. In the fully open position of the air valve 12 a lug 62 on the link 32 operated by the valve co-operates with a lug 61 on the fuel valve operating mechanism and forces the fuel valve into the position of maximum opening. The fuel valve when held on its seat acts as a fuel cut-off valve.