4 ^th Generation Diesel Common Rail System: Realizing Ideal Structure Function for Diesel Engine

Diesel injection equipment is required to be more accurate and higher in pressure to meet the increasingly strict emission, fuel consumption regulations and higher engine performance. It also needs to achieve a number of requirements such as robustness against diversified market fuels, easy installation to engine, etc. DENSO has been working to develop 4^th Generation Common Rail System (G4CRS) according to the following four concepts which are seemingly conflicting, since several years.

1. 1
   Increase injection pressure from 200 MPa to 250 MPa aiming at better spray characteristics
2. 2
   Develop a new control valve for injector to achieve zero clearance leakage and minimized switching leakage aiming at higher fuel robustness, higher fuel efficiency, smaller pump size.
3. 3
   Locate the injector actuator and control valve near the nozzle to reduce the mass of movement aiming at higher injection responsiveness accuracy.
4. 4
   Develop a new pump with pre-stroke control valve aiming at higher response for pressure control and less fuel deterioration.

This paper reports the G4CRS concepts, structure and performance combining high pressure up to 250 MPa as well as excellent fuel robustness and reliability. NOx and PM emission were reduced drastically and Fuel consumption was improved.