Tuesday, June 26, 2012

No. 546: A gasoline engine with 20% higher fuel efficiency (June 26, 2012)

Hatamura Engine Research Office, one of the subsidiaries of Honda Motor, developed a gasoline engine that is 20% higher in fuel efficiency jointly with Yasuo Moriyoshi of Chiba University. The new engine incorporates the advantages provided by a diesel engine. A gasoline engine burns gasoline using spark plugs, while a diesel engine ignites fuel when it is compressed. The system is called Homogeneous Charge Compression Ignition (HCCI) that merges the two types of engines. Although lots of efforts have been made to improve the HCCI, it is rather hard to put it into practical use because (1) It has a low burning temperature and low output and (2) It is unworkable when engine revolution is low.

The research members allowed the HCCI to import part of exhaust to the explosion chamber to increase the temperature inside for a bigger output. In addition, they created temperature difference inside the explosion chamber by flowing mixture gas in whorl. They successfully increased the output of the new HCCI by about 30% over the existing HCCI and made it workable even in time of low output. The new HCCI comes with spark plugs, but they are used only in sudden acceleration and for going uphill. They are improving the new system for smoother change between the ignition in compression and the ignition by the spark plug. They plan to put the new HCCI into practical use in 5-10 years and wish the production cost increase to be between 50,000 and 100,000 a unit. 

General Motors Makes HCCI a Reality

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