Image Number 4 for United States Patent #5879595.
An internal vent system contains a pressure sensing orifice located in a carburetor main bore or an auxiliary bore. In one embodiment, this orifice is moved thereby sensing different combinations of total and static pressure of the moving gas stream in which it is located. In another embodiment, the orifice is fixed with a moveable restrictor which changes the gas flow velocity across the orifice and thus changes the pressure sensed by the orifice. The pressure in this orifice establishes the average reference pressure for a float bowl carburetor or a wet diaphragm carburetor, and hence establishes the fuel flow through the carburetor. This adjustable vent is effective in changing fuel delivery over a wide range of engine operating conditions, and is able to minimize the need for changing high speed jets or mid-range calibrations due to changing atmospheric conditions or other operating parameters. The vent movement can be manual or automatic. One such vent of this invention can be used to vent and regulate multiple carburetors, providing lower cost and easier installation and adjustment. This vent is easily adaptable to existing conventional carburetors.