Production Feasible DME Technology for Direct Injection CI Engines 2001-01-2015
DiMethyl Ether (DME) has been shown to be a very attractive fuel for low emission direct injection compression ignition (DICI) engines. It combines the advantages of the high efficiencies of diesel cycle engines with soot free combustion. However, its greatest drawback is the need to develop new fuel injection and handling systems.
Previous approaches have been common rail type injection systems which have shown great potential in reducing harmful exhaust emissions and achieving good engine performance and efficiency due to good control of both the fuel injection characteristics and temperature. The concept also has proven benefits with respect to convenient and safe fuel handling. The logical evolution of this concept simplifies the fuel system and avoids special components for DME handling such as high pressure rail pumps while retaining all the benefits of the common rail principle.
This system uses hydraulically intensified fuel injectors driven by oil in a common rail concept using digital valve technology. Such an approach shifts the high pressure to the oil which is more convenient in its handling than DME. Furthermore, amplifier pistons enable significantly higher injection pressures to be achieved while maintaining fuel pressures outside the injector at moderate levels.