Southwest Research Institute

David P Meyers

Robert Wayne Burrahm

John Craig Hedrick

Gary D Bourn

John Thomas Kubesh

Kevin D Beaty

A method of operating a two-cycle internal combustion engine under low load conditions. A throttle is placed at the intake air system to reduce air intake into the engine cylinders. A pump is placed in the exhaust system, such that it creates reduced pressure downstream of the exhaust valves. In this manner, when the air intake ports close, the exhaust is evacuated and the air trapped in the cylinder is reduced. This permits fuel to be reduced so that the engine may operate in a low load state without losing combustion.

Method of operating uni-flow two-cycle engine during reduced load

The system for controlling the air/fuel mixture introduced into a lean burn engines includes a fuel/air mixing carburetor that is connected to the intake conduit to the engine and an air by-pass conduit that is also connected to the intake conduit. The main throttle valve is located downstream of the connection between the carburation conduit and the by-pass conduit so that mixing of the carbureted fuel/air mixture with the by-pass air occurs upstream of the main throttle valve. Accordingly, the main throttle valve does not control the air/fuel ratio but rather controls the quantity of fuel being introduced into the engine. The by-pass throttle valve may be controlled by an oxygen sensor in the exhaust system or by a fuel sensor in the intake system, when operating on natural gas, gasoline, hydrogen or alcohol fuel, as desired.

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San Antonio, TX, United States of America

David P Meyers