Carburetor

Claim 2

A multiple stage internal combustion engine carburetor comprising a small primary mixture conduit with capacity for airflow at only relatively low rates, a large secondary mixture conduit with capacity for airflow at relatively high rates, means to supply fuel to said mixture conduits, primary and secondary fuel metering means respectively associated with said primary and secondary mixture conduits wherein only said primary fuel metering means includes venturi means disposed in said primary mixture conduit to regulate fuel flow thereto in accordance with airflow therethrough and wherein said secondary fuel metering means includes an air valve disposed in said secondary mixture conduit, means controlling said air valve whereby its rotative position is determined by and is a measure of the rate of airflow through said secondary mixture conduit, a fuel nozzle discharging into an unrestricted portion of said secondary mixture conduit downstream of said air valve, a metering rod regulating fuel flow through said nozzle, and means connecting said air valve and said metering rod to position said metering rod in accordance with air valve position whereby fuel flow through said nozzle is regulated in accordance with the rate of airflow through said secondary mixture conduit, and wherein said carburetor further comprises primary and secondary throttle valves respectively disposed in said primary and secondary mixture conduits, and means to sequentially open said primary and secondary throttle valves.

Claim 3

A multiple stage internal combustion engine carburetor comprising fuel bowl means, a primary mixture conduit, a Primary throttle valve disposed in said mixture conduit, venturi means disposed in said mixture conduit, a primary fuel passage extending from said fuel bowl means and terminating in a nozzle discharging in said venturi means, a secondary mixture conduit including an inlet for secondary airflow and a mixture outlet, a secondary throttle valve disposed in said mixture outlet, an air valve rotatably disposed in said secondary mixture conduit, means controlling said air valve whereby its rotative position is determined by and is a measure of the rate of secondary airflow, a secondary fuel passage extending from said fuel bowl means and terminating in a secondary nozzle discharging in said secondary mixture conduit downstream of said air valve, a metering orifice in said secondary fuel passage, a metering rod varying the effective area of said orifice, means connecting said metering rod and said air valve to withdraw said rod from and increase the effective fuel discharge area of said orifice during opening rotation of said air valve, and means to sequentially open said primary and secondary throttle valves, said secondary mixture conduit being otherwise unrestrictive to airflow and having an airflow capacity substantially exceeding the airflow capacity of said primary mixture conduit whereby the carburetor combines a large capacity for airflow with sensitive fuel metering in the low airflow ranges.

Claim 4

A multiple stage internal combustion engine carburetor comprising fuel bowl means, a primary mixture conduit, a Primary throttle valve disposed in said mixture conduit, venturi means disposed in said mixture conduit, a primary fuel passage extending from said fuel bowl means and terminating in a nozzle discharging in said venturi means, a secondary mixture conduit including an inlet for secondary airflow and a mixture outlet, a secondary throttle valve disposed in said mixture outlet, an air valve rotatably disposed in said secondary mixture conduit, means controlling said air valve whereby its rotative position is determined by and is a measure of the rate of secondary airflow, a secondary fuel passage extending from said fuel bowl means and terminating in a secondary nozzle discharging in said secondary mixture conduit downstream of said air valve, a metering orifice in said secondary fuel passage, a metering rod varying the effective area of said orifice, means connecting said metering rod and said air valve to withdraw said rod from and increase the effective fuel discharge area of said orifice during opening rotation of said air valve, and means to sequentially open said primary and secondary throttle valves, said secondary mixture conduit being otherwise unrestrictive to airflow and having an airflow capacity substantially exceeding the airflow capacity of said primary mixture conduit whereby the carburetor combines a large capacity for airflow with sensitive fuel metering in the low airflow ranges.

Claim 5

The carburetor of claim 2 wherein said means connecting said metering rod and said air valve includes a cam positioned by said air valve and a follower connected to said metering rod and positioned by said cam for controlling the position of said rod relative to said metering orifice.

Claim 6

The carburetor of claim 2 which further includes a primary metering orifice in said primary fuel passage, a primary metering rod controlling the effective area of said primary orifice, and means controlling said primary metering rod in response to the pressure in one of said mixture conduits downstream of the associated throttle valve to provide a relatively restricted effective area of said primary orifice at pressures below a predetermined value and to provide a relatively unrestricted effective area of said primary orifice at pressures above a predetermined value.