Walbro Engine Management, L.l.c.

Walbro Corporation

Thomas L Schmidt

George M Pattullo

Martin N Andersson

David L Thomas

In at least some implementations, a charge forming device includes a body defining at least part of a first passage, a throttle valve movable relative to the first passage between an idle position and a wide open position, an air bleed passage communicated with the first passage, and a control valve. The control valve may be arranged in the air bleed passage to selectively inhibit or prevent air flow to the first passage from the air bleed passage. And the control valve is moveable between a first position and a second position in response to movement of the throttle valve wherein greater air flow is permitted from the air bleed passage to the first passage in the body when the control valve is in the second position than when the control valve is in the first position.

Charge forming device with air bleed control valve

In one form, a carburetor may include an air passage, a fuel and air mixing passage, a throttle valve, an air valve and a lost motion coupler interconnecting the air valve and the throttle valve. The throttle valve may be disposed in communication with the fuel and air mixing passage and moveable between an idle position and an open position permitting an at least somewhat less restricted fluid flow therethrough than when the throttle valve is in the idle position. The air valve may be disposed in communication with the air passage, and moveable between closed and fully open positions to control air flow through the air passage. The lost motion coupler may permit a limited movement of the throttle valve away from its idle position without a corresponding movement of the air valve, and may also permit movement of the air valve along with the throttle valve after said limited movement and until the air valve is fully open, and may also permit further movement of the throttle valve to its wide open position after the air valve is fully open.

Air scavenging carburetor

A method and system for controlling a light-duty combustion engine and, more particularly, a method and system that use an engine speed governor to limit the engine speed to a level that is less than a clutch-in speed of a centrifugal clutch. If it is determined that an operator is attempting to throttle or accelerate the engine, the engine speed governor is disengaged so that normal operation can commence.

Controlling a light-duty combustion engine

A charge forming device includes a body with a fuel and air mixing passage, a bypass passage that communicates with the fuel and air mixing passage, a throttle valve and a choke valve. The throttle valve is movable between idle and wide open positions and operable to control at least in part the fluid flow through the fuel and air mixing passage. The choke valve is movable between an open position permitting a substantially free flow of air into the fuel and air mixing passage and a closed position at least substantially restricting air flow into the fuel and air mixing passage. A bypass valve is movable between an open position and a closed position to selectively permit fluid flow through the bypass passage. The bypass valve is movable toward its open position when the throttle valve is displaced at least a threshold amount away from its idle position.

Charge forming device with controlled air bypass

For a four-stroke engine, a carburetor with a fuel pump diaphragm which defines a fuel pump chamber on one side and a pressure pulse chamber on its other side in communication with the engine to receive pressure pulses which actuate the fuel pump diaphragm to draw fuel into the carburetor and to discharge fuel under pressure to a downstream fuel metering assembly. An air passage communicates an air supply with the pressure pulse chamber to provide an air flow within the pressure pulse chamber which sweeps away, dries out or aerates and removes any liquid fuel within the pressure pulse chamber to avoid puddling of liquid fuel therein. In one form, a throttle valve carried by the carburetor body for movement between idle and wide open positions also actuates a valve which controls the flow of fluid through the air passage as a function of the position of the throttle valve.

Growing community of inventors

Cass City, MI, United States of America

Thomas L Schmidt