GB1443212A - Carburettors for internal combustion engines safety control circuit - Google Patents

Abstract

1443212 Spray carburetters SOC INDUSTRIELLE DE BREVETS ET D'ETUDES 30 Oct 1973 [30 Oct 1972] 50472/73 Heading F1B I.C. engine carburetter comprises an induction conduit, a Venturi passage 3, a main fuel supply delivering into the Venturi, a driver controlled throttle valve 2, an auxiliary throttle valve 5 moved by temperature responsive means towards its closed position when the engine is cold and means for temporary enrichment of the air-fuel mixture comprising an auxiliary fuel circuit having an outlet 13 which is downstream of the valve 5 in the closed position thereof and upstream of the valve 5 when it is open, the circuit including closure means 20 controlled by means 15 responsive to the pressure in the induction conduit downstream of the main throttle valve 2 and which close the closure means 20 when the engine is operating at low load and open the closure means when the engine is operating at full load and also including a well 10 connected to the float chamber 4 by a submerged jet 11 and having an air intake passage 28 the delivery end of which is lower than the fuel level in the float chamber, a fuel passage 12 of the auxiliary fuel circuit opening into the bottom portion of the well. Operation. When the engine is cold but operating under load the absolute pressure in the intake pipe is high and spring 19 moves diaphragm 15 and valve-member 20 off its seat and fuel is drawn off at outlet 13 by the depression at the edge of valve 5. Initially only fuel is drawn off to provide a rich mixture for acceleration, but as the fuel level in well 10 falls, air entering through an orifice 29 forms an emulsion with the fuel to weaken the mixture. When the engine temperature exceeds 20‹C the valve 5 opens sufficiently for the outlet 13 to be upstream of the edge of the valve and the only enrichment of the mixture is then due to the choking effect of valve 5 on the main jet system. At partial load with a cold engine, the low absolute pressure downstream of the main throttle valve acts on diaphragm 15 and closes valve 20. When the engine is hot a lever 25 secured to the spindle of valve 5 engages a piston valve 22 and moves it down to close the passage 12.