Search Results

An electronic fuel/air mixture controller has been developed which is designed to reduce exhaust emissions on small utility engines. Lean Power Corporation has conducted a field study using this controller in cooperation with the United States Postal Service. Additional laboratory testing was performed in cooperation with the U.S. Environmental Protection Agency using the SAE J1088 test procedure. In this study, electronic air/fuel mixture controllers were installed and exhaust emissions evaluated on a sample of lawnmowers and engines. A significant reduction was achieved in Carbon Monoxide and the sum of Hydrocarbons plus Oxides of Nitrogen with the electronic mixture controller.

Although an engine's lean limit fuel-air ratio may be easily found experimentally, it is difficult to predict accurately due to the influence of speed, load, ambient conditions, ignition characteristics, fuel chemistry, engine wear, etc. This paper will describe a new closed loop feedback control which adaptively tracks the engine's instantaneous lean limit using only one engine sensor. Test data is presented which indicates the control system response to changes in ignition timing, fuel chemistry, speed, and load. Results from laboratory and field tests indicate a significant improvement over programmed fuel-air scheduling systems, both in fuel economy and exhaust emissions.