A New Engine Control Concept to Help Achieve Light-Duty Euro V Emissions, 03-9387

Printer Friendly Version

Principal Investigator
Shizuo Sasaki

Inclusive Dates: 04/01/03 - Current

Background - Meeting the upcoming Euro V emission standard is a significant challenge for car manufacturers. Traditional technology, so to speak "engine modifications," may become ineffectual. It is said that the main-stream of emission control technology of diesels should be changed from engine modification to full-fledged exhaust treatment system (four-way catalyst system). As a
four-way catalyst system, LNT (Lean NOx Trap) + DPF (Diesel Particulate Filter), is one of the most successful ways for light-duty diesel engines. The objectives of LNT + DPF system are as follows:

  1. Maintain catalyst bed temperature over light-off temperature at light load condition without sacrificing fuel economy.
  2. Realize rich condition in catalyst to reduce NOx with minor fuel penalty.
  3. Realize rich and very high ambient temperature to regenerate sulfate with minor fuel penalty.
  4. Realize lean and very high ambient temperature to oxidize accumulated particulate matter with minor fuel penalty.

Approach - To solve these difficulties, two new combustion technologies, LTC (Low Temperature Combustion) and PCCI (Premixed Controlled Compression Ignition) are introduced. To optimize these new combustion technologies, control over the EGR gas temperature and amount is used. The first step of this study is realizing: 1) high bed temperature over light-off temperature at low load/speed condition; 2) rich condition for NOx reduction; 3) rich and high bed temperature (>600ºC); and 4) lean and high temperature (>600ºC) at steady state condition. The second step is demonstrating: 1) NOx reduction; and 2) sulfur regeneration while evaluating fuel penalty.

Accomplishments - Test results obtained in the first-step study (steady-state test) are as follows:

  1. Sufficient bed temperature (>300ºC) was realized at low load/speed condition by LTC.
  2. Rich combustion was realized at low load/speed condition by LTC (air fuel ratio <12.5).
  3. Rich and very high bed temperature (>600ºC) was realized at medium load by LTC.
  4. Rich combustion was realized (air fuel ratio <14) at medium load (highest representative load point of FTP75 mode) by adding a minimum post injection, but the turbo inlet temperature was at the max limit (750ºC) and the engine out smoke was high. (In the following study, it was confirmed that exhaust temperature was reduced with rich operation duration and predicted the possibility of engine-out soot reduction by injection timing retardation.)

2003 Program Home