Hiromi Ishitani

Behavior of Adhering Fuel on Cold Combustion Chamber Wall in Direct Injection Diesel Engines

Comportement du carburant qui adhere aux parois froides de la chambre de combustion dans les moteurs diesel a injection directe

Study of melting phenomenon of frost and ice on the windshield

Frost and ice were accumulated on the windshield in winter. Generally to melt it, warm air using engine coolant is blown on the inner surface of the windshield, though, the time to melt is over 10 min under the lower temperature condition. In this study to shorten the melting time, the electric power systems of the heating element and the clear heating film were compared with the defroster system and the factors influencing the melting were investigated.

The Transient Performance during Acceleration in a Passenger Car Diesel Engine at the Lower Temperature Operation

Diesel passenger car is superior to gasoline engine car in the fuel economy, but it has some defects to improve: noise, startability, particulate and transient performance, etc. Among these problems, this paper presents particularly transient performance in a diesel engine and clarifies the causes of its decline at lower temperature operation. As the results, it is found that the transient torque at the early stage of acceleration is only 50% at -20/sup 0/C, and that when coolant temperature went up to 20/sup 0/C, the transient torque approaches to that of the warmed up engine. The transient response become worse with retarding the injection timing and with decreasing the engine speed. On the other hand, since the normal response is not obtained despite using high cetane number fuel, main cause of the inferior transient torque is not the poor combustion, but the increase of friction or cooling loss.

Effect of Heat Insulation of Combustion Chamber on Exhaust Emission in a DI Diesel Engine.

In a small direct-injection diesel engine (bore : 86 mm, stroke : 90 mm), effects of heat insulation of the combustion chamber on engine performance (fuel consumption, nitric oxide, amount of unburned HC and exhaust smoke characteristics) were investigated by changing the combustion chamber materials, by inserting a teflon sheet between the piston body and piston crown and by creating an air gap behind the combustion chamber. The effect of heat insulation on the surface of the combustion chamber was the greatest for ceramics and next greatest for the case of teflon sheet insertion. The HC concentration with increasing heat insulation decreases about 15% under light load and medium load but increases under high load due to changes in the combustion pattern. The effect of heat insulation on smoke and fuel consumption characteristics is small under light load but large under high load. The smoke and fuel consumption characteristics under high load deteriorate with increasing heat insulation.