Meteringrod carburetor

Claim 1

A carburetor for Otto cycle engines comprising: a. a carburetor body including at least one main passage, said passage beginning with an air inlet which connects to a fuel mixing region (7) which leads to a mixture outlet, b. a throttle disposed in said passage between said air inlet and said mixing region, c. a solid fuel metering orifice (2) connecting to said mixing region, d. a diaphragm chamber comprising a diaphragm, a fuel inlet valve and means linking said diaphragm to said fuel inlet valve, said diaphragm chamber feeding fuel to said fuel metering orifice, e. a second larger foam metering orifice (6) shunted between said fuel metering orifice and said fuel mixing region, this orifice being coaxial with said first orifice, f. a foam chamber shunted between said fuel metering orifice and said foam metering orifice, g. an air bleed passage (5) with an air bleed orifice (4) disposed therein ducting air from an inlet opening upstream of said throttle to said foam chamber, h. a tapered meteringrod (1) including means to couple said meteringrod to said throttle in such a manner that said meteringrod is displaced substantially along its axis when the throttle is rotated, i. said meteringrod and said orifices being arranged in such a manner that said meteringrod reaches through both orifices, constricting both orifices at part load and enlarging both orifices at higher loads, said meteringrod and said orifices being so dimensioned that said foam orifice is narrowed down at idle to a fraction of the flow area of the air bleed orifice, j. the improvement comprising at least one spring acting upon said diaphragm, means to change the spring tension of at least one spring acting on said diaphragm, said means being connected to said throttle in such a manner that the effective fuel level established by said spring tension will be displaced towards said fuel metering orifice with increased throttle opening.