Diesel Engine 1
The diesel engine's task is to convert the chemical energy, embedded in a very ignition-willing fuel, as efficiently as possible and with few
emissions into mechanical energy.
Pure air is sucked in. Without supercharging a minimum compression of 18 : 1 is necessary for the combustion. (approx. 30 bar) The fuel is injected into the heated air. This takes place with a nozzle opening
pressure of around 130 bars for the outdated side combustion chamber process, making use of the modern direct injection method
substantially higher pressures are
in place. Without electric ignition system the combustion occurs immediately (self-ignition). The injection pressure is generated by a mechanical high-
pressure pump and
through nozzles, reaches the combustion chamber.
|Petrol||compared with||Diesel + 13%|
In contrast to the petrol engine there is always more than enough air in all operational stages, also without supercharging. Therefore, and because of the
high temperatures nitrogen
oxides (NOX) tent to develop more easily. The shorter mixture formation and the approx. 13% higher C concentration in the diesel fuel in comparison to petrol fuel raises also the ejection of soot (particles). The diesel
engine stands at the beginning of its exhaust gas cleaning program, the petrol-driven cars surpassed this stage already.
|Combustion procedures||System pressure||Efficiency|
|Direct-injection||Piston chamber||450 - 2.200 bar||Up to 48%|
|Side combustion chamber|
|Pre-ignition chamber||Up to 450 bar||20 - 38%|
|Subaru produces the diesel as a boxer engine|