EFFECT OF FINE DIRECT LIFT CONTROL ON IGNITION DELAY
GPD-Tech's first engine test adapted an available GPD-Tech actuator to an existing diesel fuel injector. The OEM injector solenoid and servo valve were replaced by the GPD-Tech actuator and custom hydraulic compensation chamber. The actuator, operating through the hydraulic chamber, directly lifted the injector needle. Installed on cylinder #1, the top of GPD-Tech's test apparatus projects through the valve cover of the test engine as the photograph shows.
In the graph, the dashed red line is a stock solenoid injector for comparison. The GPD-Tech injection profile was a pilot followed by a main charge. The difference between each run is that the pilot lift was varied by one micrometer. This cause was followed by effect: the delay after the pilot after which the main charge ignited varied linearly with pilot lift, a clear demonstration of the fine control GPD-Tech's actuator possesses.
In addition, the rate of heat release was observed to depend upon the rate at which current changed.