1993-03-01

Electronic Direct Injection System for Use in Methanol Fueled High Speed Engines 930930

Continual investigations into the area of alternative fuels are being conducted in an effort to reduce the emission of tomorrow's internal combustion engines. Recent efforts in both the automotive and heavy-duty industry have focused on the evaluation of methanol, ethanol, and reformulated gasoline liquid fuels in this vein.
With this advent of light fuel usage in direct injection engines, the criticality of adequately performing fuel injection equipment is amplified. Typical, unassisted, direct injection fuel systems have their roots in diesel equipment. With rare exception, standard diesel injection equipment is not directly applicable to the utilization of light fuels.
Via a program sponsored by the U.S. Environmental Protection Agency, a high speed, electronic, methanol compatible direct injection fuel system has been developed and demonstrated. The base pump design utilized for this effort was AMBAC's mechanical Model 100 diesel fuel injection pump. As a distributor type pump, the Model 100 offered minimal injection distribution variations, usually seen with light fuel applications, and utilizes an oil lubricated cam, thus relieving cam-roller wear concerns. In addition, the Model 100 has been fully upgraded to accommodate electronic controls. Hall-Effect based sensors and a linear solenoid assembly have been internally mounted within the Model 100 to accommodate independent control of injection timing and provide speed information. A rotary torque motor utilizing a non-contacting position sensor has been incorporated to provide fuel quantity control. These changes have resulted in a significant envelope reduction as compared to the baseline mechanical unit.
Results presented focus on design and development efforts aimed towards methanol compatibility and satisfactory injection characteristics. in particular, component design, material selection, injection rate shape and hydraulic tuning, electronic control adaptability, and endurance performance will be reviewed.
The efforts under this program have produced a demonstrable, methanol compatible, electronic fuel injection system. Standard componentry and manufacturing techniques have been utilized whenever possible to retain a commercially viable product. Given an increase in commercial emphasis towards light fueled direct injection applications, the Model 100 pump is a viable first step towards resolving the typical problems associated in this arena.

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