GB524419A - Improvements relating to carburettors for internal combustion engines - Google Patents

Abstract

524,419. Spray carburetters. PALLAS APPARATE GES. Jan. 30, 1939, No. 3160. Convention date, Jan. 29, 1938. [Class 7 (iii)] A spray carburetter comprises means for effecting a supplementary regulation of the fuel-air ratio in accordance with altitude changes an auxiliary chamber for supplying a rich mixture to a main mixing chamber, the inlet to or outlet from the auxiliary chamber, or both, being controlled by a regulating member which is adjusted conjointly with a main throttle or set automatically by a pressureresponsive device beyond the main throttle, and a preliminary chamber having an air inlet valve controlled by a barometric device to produce therein a pressure which is a function of the atmospheric pressure, the preliminary chamber supplying air to the auxiliary mixing chamber. A chamber 20 surrounding the air-inlet 1 communicates by a passage 19 with a closed chamber 18 containing an aneroid box 17 which controls a conical valve 16 admitting air to the preliminary chamber 13. A reduction in atmospheric pressure closes the valve 16 to shield the chamber 13 from the full effect of the reduction. The chamber 13 communicates openly with the top of the float chamber or equivalent fuel supply device and through a valve 7 with the auxiliary mixing chamber 4 which is open to the main mixing chamber 3 through a valve 8 connected to the valve 7. A fork 10 links the valves 7, 8 to the main throttle 2. Fuel is drawn into the chamber 4 through a nozzle 11, the' pressure in the chamber 4 being less than that in the float chamber and chamber 13 through its exposure to the main mixing chamber. The suction on the nozzle 11 does not fall as the pressure in the mixing chamber 3 rises with the opening of the throttle 2 since the valve 8 opens correspondingly and communication between the chamber 3 and 4 is freer. As shown in Fig. 4, a diaphragm regulator replaces the float chamber and the valves 7, 8 are actuated by an aneroid box 25 exposed to the mixing chamber 3 instead of by direct connection with the throttle valve 2. In either case, if the carburetter is used with a supercharger, the valve 16 is made of double-conical form to operate in the opposite sense while the supercharger is maintaining a constant input but to operate as described above if the carburetter is working at a height greater than that for which the supercharger can compensate.