Japanese manufacturers constantly refine their conventional engines.
SAE Tech Briefs - Jack Yamaguchi - March 2006
Although hybrids have gotten much of the media attention recently, Japanese manufacturers have been constantly refining their conventional engines. Here are some worthy of note.
The R18A 1.8-L i-VTEC inline four cylinder engine is Honda’s global inline four, first introduced in the new Civic range. Intelligent VTEC technology is employed in the engine to vary intake charge volume. Unique to the 1.8 i-VTEC engine is that the FE (fuel economy) cam, engaged during low-load operations as steady cruise between engine speeds of 1000 and 3500 rpm, delays the intake valve closing timing by 63° (94° ABDC) vs. the HO (high output) cam (31° ABDC). In FE mode, the engine operates in the adaptive Atkinson cycle, taking full advantage of the superior fuel economy by greatly reducing pumping losses.
The R18A engine produces 103 kW (138 hp) at 6300 rpm and 174 N•m (128 lb•ft) at 4300 rpm on a 10.5:1 compression ratio, and is content with regular grade unleaded gasoline. The output is 7 kW (9 hp) and 19 N•m (14 lb•ft) higher than the previous 1.7-L VTEC unit. More significant is an increase of 22 kW (30 hp) at the frequently used 3000-rpm zone, greatly enhancing on-road performance. On fuel economy, Honda cites a 6% improvement over its predecessor.
VCM is the acronym for the variable cylinder management technology that deactivates one bank of onda’s J30A 3.0-L VCM V6 engine. The engine powers Honda’s upscale models including the North American Odyssey minivan, the Japanese Elysion minivan and Inspire sedan, and is combined with the IMA hybrid system in the U.S. Accord Hybrid.
The VCM V6 is still the only one of its kind, and its switching between full-six and partial-three cylinder operation is almost imperceptible, thanks to the active engine mount system and acoustic noise suppression.
In the North American-exclusive Accord Hybrid, the SOHC four-valves-per cylinder, 2997-cm3 engine produces 190 kW (255 hp) at 6000 rpm and 315 N•m (232 lb•ft) at 5000 rpm on a 10.5:1 compression ratio, combined with the 12-kW, 136-N•m (100-lb•ft) - at 840 rpm – electric motor, and driving the front wheels via a stepped-gear, five-speed automatic transmission. EPA mileage estimate is 29 mpg city and 37 mpg highway, vs. the gasoline-engine-only Accord EX V6’s 21/30. VCM accounts for about 15% of the improvement in fuel consumption in city mode, and as much as 57% in the highway mode.
Daihatsu’s new Topaz KF is unlikely to find its way outside of its home country, Japan. However it is significant that the mini- and small-vehicle specialist has pursued and achieved its objective of a low-mass, low-friction, fuel-efficient, mini car engine. The aluminum inline three-cylinder engine displaces all of 660-cm3, the Japanese light vehicle limit, and produces 43 kW (58 hp) and 65 N•m (48 lb•ft).
The Super Intelligent three-way catalytic converter cleanses exhaust gas from the Topaz KF engine. The catalyst is the latest development of the Intelligent Catalyst that was first adopted in Daihatsu’s light cars in October 2002, and the aggregate number of units installed now exceeds 1.5 million. The Intelligent Catalyst can regenerate one of its precious metals, Palladium, as well as greatly reduce the amount of all three precious metal contents.
The Super Intelligent Catalyst further reduces precious metal contents, by 50% vs. the Intelligent Catalyst, and 70% vs. the conventional three-way catalyst, according to Daihatsu, and it now regenerates the other two precious metals, Platinum and Rhodium. Daihatsu, Japan Atomic Energy Agency, Hokko Chemical Industry, and Cataler have jointly conducted the Super Intelligent Catalyst research.