|Simple schematic of the plasma system.|
In an effort to develop a lower-cost emissions control system for diesel minicars, Daihatsu has been working with Japan’s Research Institute of Innovative Technology for the Earth on a non-thermal plasma (NTP) system for reducing particulate matter from diesel exhaust. Daihatsu engineers will present a paper on their work at the upcoming SAE World Congress in Detroit.
Daihatsu, 51.2% owned by Toyota Motor, overtook Suzuki Motor last year as the top seller of minicars in Japan. Suzuki had held the top spot for 33 years.
While sales of standard automobiles continue to drop in Japan, sales of minicars continue to climb. The total number of minivehicles sold topped 2 million for the first time last year, according to the Japan Mini Vehicles Association, based on stronger demand for fuel-efficient, inexpensive vehicles. Minicars accounted for a record 36.1% of all automobiles sold last fiscal year, which includes vehicles with engine displacements of more than 660cc.
Daihatsu—and other automakers—are concerned about the increasing cost and availability of the precious metals used in emissions control devices.
“Even if we can develop a technology [to reduce exhaust emissions], we might not be able to produce vehicles due to a lack of raw materials,” said Hirohisa Tanaka, a technical expert at Daihatsu Motor Co.
The NTP system would allow Daihatsu to leave rare metals out of the emissions aftertreatment process, and allow it to reduce costs. Daihatsu says that the system is best suited for use in minivehicles.
Innovative Approach of PM Removal System for a Light-Duty Diesel Vehicle Using Non-Thermal Plasma (SAE 2007-01-0236) Not yet published.