Refine Your Search

Search Results

Viewing 1 to 6 of 6
Technical Paper

A Study on In-Cylinder Injection of Low Pressure Natural Gas for Performance Improvement of Small Sized Two-Stroke SI Engines

2001-05-07
2001-01-1959
Small two stroke SI engines supplied with natural gas in the intake port are advantageous for low maintenance and low cost when used in co-generation systems for residential use. However in the engines with port injection systems, the unburned HC emissions are higher and thermal efficiency is lower than with 4 stroke engines. To overcome these disadvantages, an in-cylinder injection with a special low pressure injection nozzle system was attempted. The results showed that improvements in unburned HC emissions and thermal efficiency are possible due to the remarkable reduction in scavenging loss and the lean combustion.
Technical Paper

Estimation of the Total Fuel Economy and CO2 Emission from Vehicles at the Center of Local City

2001-11-12
2001-01-3759
Improvements in the fuel economy of passenger cars and trucks contribute directly to CO2 reductions. Recently low fuel consumption cars are being developed, however most cars are still old types. This study estimates the effect of new engine types, light weight cars, kinds of fuel, and running conditions on fuel economy and CO2 emissions with a new calculation method of fuel consumption. In this calculation method the fuel consumption and CO2 emissions are easily calculated from the indicated thermal efficiency and friction mean effective pressure for different engine types and sizes. By this method the overall fuel consumption and CO2 emissions from small passenger cars to heavy duty trucks were estimated for roads through the center of a small city. As a result, the influence of new type engines, light weight cars, fuel properties and driving patterns on fuel economy and CO2 was made clear.
Technical Paper

Effect of Ignition Delay and Exhaust Gas Speed on Exhaust Odor in DI Diesel Engines

2002-10-21
2002-01-2883
This study investigated the effect of ignition delay and exhaust gas speed on exhaust odor in DI diesel engines. From the investigation of many engine parameters like injection timing and injection pressure, it has been found that the optimum ignition start position is more important than the shorter ignition delay, but the optimum ignition start position along with the shorter ignition delay is the best scenario for minimum odor. Further, it has been found that good mixture formation is more important than shorter ignition delay in reducing odor, but the optimum mixture formation together with shorter ignition delay results in the lowest odorous emissions. From the investigation of various fuels in the diesel engine, it seems that the combustion pattern and the raw odor of fuel are more important than ignition delay. A fuel with low raw odor and high cetane number with optimum boiling point significantly improves the exhaust odor.
Technical Paper

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

1985-02-01
850113
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°C, and that when coolant temperature went up to 20°C, the transient torque approaches to that of the warmed up engine. The transient response becomes worse with retarding the injection timing and with decreasing the engine speed. On the other hand, since the normal response is not obtained despite of 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.
Technical Paper

A Study of Lean Burn of a 4 Stroke Gasoline Engine by the Aid of Low Pressure Air Assisted In-Cylinder Injection - Part II

1999-10-25
1999-01-3689
Lean-burn engines now being developed employ in-cylinder injection which requires high pressures and so necessitates expensive injection equipment. The injection system proposed here is an air assisted in-cylinder injection system which is injecting a mixture of air and fuel in the cylinder during the intake stroke and allowing atomization at lower injection pressures than those necessary in compressing fuel with a usual solid injection. This time, the experiments used a testing engine of a 4 stroke gasoline OHV type replacing the Side Valve type. Performance with a small depression in the main combustion chamber was investigated with a spark plug and reed valve installed in the depression. The engine was operated then following the same method as last year (SAE 982698). As a result, the lean burn method employed here was possible over a wide range of engine speeds and loads. Moreover, it was also shown that this operation was possible with a fully opened throttle valve.
Technical Paper

Effects of a Hybrid Fuel System with Diesel and Premixed DME/Methane Charge on Exhaust Emissions in a Small DI Diesel Engine

1999-05-03
1999-01-1509
Early stage combustion systems, with lean homogeneous charge compression ignition (HCCI), have been studied, with the intent to decrease the pollutant emission characteristics of DI diesel engines. Early stage combustion enables drastic reductions in both nitrogen oxides (NOx) and smoke emission, but the operating load range is restricted, due to combustion phenomena, such as unsteady combustion and knocking. In this study, we explored the possibility of broadening the operating load range in HCCI and reducing pollutant emissions using Dimethyl Ether (DME) fumigated through the intake pipe. However, the improvements in load range were found to be less than 0.1 MPa in brake mean effective pressure (BMEP), even when compression ratios were reduced and Methane with high octane number was mixed. Therefore, a DME premixed charge could be used only at light loads. At heavier loads a hybrid fuel system with a DME premixed charge and diesel fuel injection is necessary.
X