Norihiro Sawa

Compression ignition engine using composite emulsified fuel. Engine performances and combustion characteristics under transient operation.

Transient engine performance, fuel injection and combustion characteristics of prechamber-type compression ignition engines operated with a composite emulsified fuel (composed of gas oil, water and methanol) were investigated. As a result, response of engine speed of composite fuel operation was found to be the same as the gas-oil operation. However, The start of injection timing under transient running was slower than that of steady-state operation. The retarded and fluctuated start of injection timing was caused by the vibration of the pump axis under transient running and the unstable air content of a composite fuel. Therefore the retarded and fluctuated start of injection timing increased the ignition lag and its fluctuation.

The engine performances and exhaust gas characteristics of methanol-fueled two-cycle engines.

The engine performances and exhaust gas characteristics of methanol-fueled two-cycle engines were investigated. The operating conditions such as engine speed, ignition time, throttle valve opening, air fuel ratio, and compression ratio were widely varied to operate the carbureted methanol engine. Furthermore, the electric-controlled fuel injection nozzle which is installed at the scavenging port was employed to operate the methanol engine. As a result, at the operating field of high engine speed and lean mixture, the brake thermal efficiency with the best ignition time of the two-cycle engine was compared with that of a four-cycle engine, and at the above-mentioned operating conditions, the combustion variations and the harmful exhaust emissions of the two-cycle methanol engine showed relatively low levels.

EFFECT OF VARIOUS FACTORS ON THE SMOKE EMISSION FROM A SWIRL-CHAMBER TWO-CYCLE DIESEL ENGINE UNDER TRANSIENT RUNNING CONDITIONS

To determine definitely the transient characteristics of smoke emission from a diesel engine, it is necessary to know details of its power transmission elements such as fuel injection system, combustion process, engine rotating system and its friction losses. Previous studies have been unclear about the relations between the engine performance, smoke characteristics and influence of operating conditions, especially on the two-cycle engine. Therefore, the authors carried out the experiments while changing its brake load and fuel pump rack, respectively, to examine the effects of the operating conditions on the exhaust smoke density under transient operations. (A) For the covering abstract see IRRD 865952.

PEAK VALUE OF DELIVERY RATIO IN TWO-STROKE MOTORCYCLE ENGINE

The amount of intake air in a two-stroke motorcycle engine was studied by considering the influences of atmospheric conditions and various engine factors, taking note of inertial limitation on the maximum delivery ratio. The influence of the intake and exhaust pipes was determined by considering the following: pressure at the entrance of the intake pipe, boost pressure, atmospheric temperature, mixture ratio, and back pressure. The influence of engine dimensions was determined by considering carburetor opening, dimensions of intake pipe, crankcase volume, engine size, and port opening period. Theoretical results correspond fairly well with experimental data.

The Effect of an Intake Pipe System on the Fuel Flow Amount of a Small Type Two-Stroke Cycle Engine

To examine the influence of the pressure wave in an intake pipe system on the fuel flow quantity of a crankcase compressed two-stroke cycle gasoline engine, the authors carried out some experiments and then analyzed numerically on the unsteady characteristics of a simplified carburettor. Some conclusions reached are summarized as follows. (a) The fuel flow quantity from a carburettor decreases in inverse proportion to the amplitude of the pulsation wave acting on the carburettor throat and that is governed by the matching condition q*=15·a/N(LS+Δl). (b) When the throttle valve of carburettor is a small opening, the fuel flow quantity increases with the engine speed and the length of the main fuel pipe system because of the inertia effect of fuel liquid column in the main fuel pipe. (c) To prevent the variation of excess air ratio with the engine speed, the utilization of a Helmholtz resonator with elastic wall is effective.