Study on internal combustion engines relies on the combination of the high specific output power and low efficiency of diesel engines at part loads.
Research has shown that direct injection (DP), gasoline engine with throttle-free control for the load of a spark-ignition four-stroke engine can achieve this goal. Direct injection engines use direct injection to inject the fuel directly into the cylinder during the compression or suction stroke. The mixture is then formed. These engines can be compared to diesel engines in that they allow you to adjust the engine’s output power by changing how much fuel is injected into thecylinder. Pumping is greatly reduced since the air is inhaled directly into the cylinders. The mixture is ignited by a spark plug. This eliminates the need for spontaneous ignition conditions in the mixture as with diesel engines. This creates lean working conditions and reduces specific fuel consumption. These progressively charged engines have low and medium loads. Fuel is injected into the combustion chamber just before sparking at spark plug. The fuel/air ratio changes in this situation, so the mixture is rich near spark plug but poor elsewhere. The engine will operate with a lean mixture if the interior of the piston is taken as a whole. The mixing ratio drops to 1/40 in idle conditions. Full load operating conditions require that fuel be injected into cylinders at the moment of intake. This ensures that the mixture remains homogeneous and is stoichiometric.
In DP engines, fuel is slowly injected into the cylinder at each intake stroke. This cooling of the air and increasing volumetric efficiency (pre injection) are the results. When the piston approaches the top deadcenter (TDC) during the compression stroke, the main injector is activated. Concave piston crown allows for concentrated fuel (rich mixture) around the sparkplug, ensuring a good ignition. DP gasoline engines are able to operate in partial loads even with very lean mixtures (40/1).
The specially shaped pistons and intakemanifolds of DP gasoline engines are matched to each other. This creates turbulence inside the combustion chamber and mixes the fuel and the air perfectly. This improves combustion efficiency, reduces pollutant emissions, and allows for the adjustment of fuel/air ratios over a wide range. Smooth combustion is possible even at low idle speeds. Additionally, the engine speed can easily be adjusted over a broad range. DP gasoline engines offer a 40% increase in fuel economy when idle, compared to conventional engines.
