直接噴射式二サイクルメタノール機関の研究

抄録

A direct fuel-injection two-stroke cycle engine operated with neat methanol was investigated. The engine performances, combustion and exhaust gas characteristics were analyzed experimentally and were also compared with the results of operations with a carburetor, EFI injection at the intake manifold, and EFI injection at the scavenging port. As a result, the power and the brake thermal efficiency of the direct fuel-injection engine were higher than those of engines operated with a carburetor and the above two EFI methods. The exhausted unburned fuel of the direct fuel-injection engine was lower than that with operation with a carburetor, and holmaldehyde and CO concentration were of the same level as the operations with the carburetor and EFI methods. The NO_x concentration of the direct fuel-injection was half the level of the result of carburetor operation. Because a stratified charge using direct fuel-injection activated the combustion of the lean mixture which increases working gas temperature, therefore, the vaporization of injected fuel was promoted by the elevated temperature of the residual gas.