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Technical Paper

Degradation of DeNOx Performance of a Urea-SCR System in In-Use Heavy-Duty Vehicles Complying with the New Long-Term Regulation in Japan and Estimation of its Mechanism

2016-04-05
2016-01-0958
Degradation of the deNOx performance has been found in in-use heavy-duty vehicles with a urea-SCR system in Japan. The causes of the degradation were studied, and two major reasons are suggested here: HC poisoning and deactivation of pre-oxidation catalysts. Hydrocarbons that accumulated on the catalysts inhibited the catalysis. Although they were easily removed by a simple heat treatment, the treatment could only partially recover the original catalytic performance for the deNOx reaction. The unrecovered catalytic activity was found to result from the decrease in conversion of NO to NO2 on the pre-oxidation catalyst. The pre-oxidation catalyst was thus studied in detail by various techniques to reveal the causes of the degradation: Exhaust emission tests for in-use vehicles, effect of heat treatment on the urea-SCR systems, structural changes and chemical changes in active components during the deactivation were systematically investigated.
Technical Paper

Piston Slap Motion and Engine Noise under Low Temperature Idling Operation of Diesel Engines

1983-02-01
830066
Diesel engines make a shrill noise called “idle knock” under low temperature idling operation. This causes a serious noise pollution problem in automobile diesel engines. It was clarified by this study that one important source of this noise was piston slap impulse. Piston slap motion was measured under usual operating conditions and a condition with additional oil supplied into the piston clearance. The piston slap motion was calculated taking into account the frictional resistances of the crank mechanism and squeeze action of oil film. It was concluded that only a negligible amount of oil existed in the piston clearance for the squeeze action.
Technical Paper

A Study of Decrease Oil Consumption for NSOR-Two-Ring Package Piston

1991-02-01
910435
Furuhama(1)* proposed the new two ring package consist of a pressure ring and a narrow single-rail oil ring (NSOR) in 1985. Number of studies(2) have been done for the purpose of reducing the oil consumption (OC) in this ring package. However, OC reduction problem has been still remaining to solve as only one serious problem of this ring package. The reasons of a larger OC in the new ring package than the conventional three ring has been hardly understood, considering the OC control ability on second ring in three ring package will not so large since the fact that the oil film thickness is thicker than that of the oil ring. In this study, the mechanism of OC increase in new ring package was found out at last, as a result, OC of new ring package piston was improved up to the same level of conventional three ring package piston.
Technical Paper

Measurement of Cylinder Bore Deformation During Actual Operating Engines

1991-02-01
910042
One of the phenomena accompanying the lightweight/compact/high power output feature of engines is the cylinder bore deformation, which may readily cause increased oil consumption, gas leakage, unusual wear, scuffing, etc.. The authors have had experiences that piston rings had generated contact failure during engine operation (1)*. Such deformation is generated as a combination of the static deformation due to head bolt tightening, crankshaft installation, etc., and the deformation by the operating factors; thermal load and combustion pressure. Countermeasure of design have been made for the former (2)*, and prediction of the deformation during actual operating have been tried using FEM analysis, etc. for the latter (3)*. Therefore, the accurate measurement result have been required strongly, for a long time. But it could not be realized in the past.
Technical Paper

Low NOx Emission Automobile Liquid Hydrogen Engine by Means of Dual Mixture Formation

1993-03-01
930757
According to authors' previous research, high pressure hydrogen engines with direct injection right before TDC and spark ignition obtain high performance and eliminate almost. abnormal combustion. This study has clarified the mooted points in the flame propagation to adjacent jets and the control of the optimum spark timing and large NOx emissions even in leaner than excess air ratio of λ=2. Nitric oxides (NOx) is the only the pollutant in the exhaust gases emitted by hydrogen engines. It has been found that the NOx formation largely depends on the mixture formation method. In order to operate the engine in a small amount of NOx, an experimental study was carried out to investigate the reduction of NOx and the output power by using dual mixture formation method, external mixture formation and direct injection.
Technical Paper

Effect of Piston and Piston Ring Designs on the Piston Friction Forces in Diesel Engines

1981-09-01
810977
How much reduction in piston friction loss can be achieved by the piston design? Piston friction force measurements have been carried out using the measuring method developed by the authors to obtain the effects of piston clearance, surface roughness, lubricant and ring size and contact pressure on the piston friction forces. A particular emphasis is placed on the study of effects of the piston rings by the experimental and theoretical analyses, since friction forces of piston rings accounted for 3/4 or more of the total piston friction force.
Technical Paper

Development of a Technique to Predict Oil Consumption with Consideration for Cylinder Deformation - Prediction of Ring Oil Film Thickness and Amount of Oil Passing Across Running Surface under Cylinder Deformation -

2003-03-03
2003-01-0982
Although various factors affecting oil consumption of an internal combustion engine can be considered, a technique to predict the amount of oil consumed within a cylinder that passes across a running surface of a ring was developed in this study. In order to predict the effect of cylinder deformation on oil consumption, a simple and easy technique to calculate the oil film thickness in deformed cylinder was proposed. For this technique, the piston ring was assumed to be a straight beam, and the beam bends with ring tension, gas pressure, and oil film pressure. From the calculated oil film thickness, amount of oil passing across the running surface of the TOP ring and into the combustion chamber was calculated. The calculated results were then compared to the oil film thickness of the ring and oil consumption measured during engine operation, and their validity was confirmed.
Technical Paper

Study on Mechanism of Backfire in Hydrogen Engines

1994-10-01
942035
In this study, the cause of backfire concerning an external mixture formation type hydrogen engine was clarified. It has been known that the maximum output power of the external mixture formation type hydrogen engine should be kept significantly low, because of backfire. Generally, the backfire of this type of hydrogen engine is caused by pre-ignition. In this type of hydrogen engine, pre-ignition occurred for a range of lean mixture. Under this study, therefore, the relationship between the occurrence of backfire and the temperature at the tip of the spark plug electrode, and the detection of the luminescence spectrum of the flame near the spark plug were examined and studied in relation to the spark plug ignition theory which appeared to be promising. Then the pre-ignition timing and location were studied by detecting the flame luminescence spectrum.
Technical Paper

Measurement of Piston-Skirt Deformation in Engine Operation by Means of Rotating Cylinder with Gap-Sensors

1993-03-01
930717
An unique measurement method was developed for measurement of the piston outer surface during the engine operation. The method was realized by embedding a gap sensor into a cylinder bore and by rotating the cylinder in the circumferential direction. By means of this method, interesting data of skirt deformation of a gasoline engine caused by temperature, pressure and the slap force were obtained.
Technical Paper

The Effects of Crank Ratio and Crankshaft Offset on Piston Friction Losses

2003-03-03
2003-01-0983
A study was conducted to understand the effects the specifications of the crank-slider mechanism have on piston friction losses. The information obtained through the study is believed to be useful information for reducing the piston friction. A single-cylinder spark-ignited gasoline engine was designed and constructed to have not only a real-time piston friction measurement system using the floating liner method, but also provisions to facilitate changing the specifications of the crank-slider mechanism. This paper describes the study results obtained under various engine-operating conditions and reports the parametric test results of three crank ratios and five crankshaft-offset amounts tested.
Technical Paper

A Study on Hybrid Control Method for Improvement of Fuel Economy and Exhaust-Gas Emission of Hybrid Trucks

2015-09-01
2015-01-1780
Next-generation vehicles which include Electric Vehicles and Hybrid Electric Vehicles are studied and expected to reduce carbon dioxide emissions. The number of small delivery hybrid trucks has increased in the commercial vehicle class. The engine load of a commercial hybrid truck is reduced by using an electric motor. Fuel economy of the hybrid truck is improved with the assist. On the other hand, exhaust-gas temperature is decreased, and it has a negative effect on the purification performance of aftertreatment system. In this report, the fuel performance and emission gas characteristics of marketed small hybrid trucks were surveyed using the chassis dynamometer test system.
Technical Paper

Friction and Lubrication Characteristics of Piston Pin Boss Bearings of an Automotive Engine

1997-02-24
970840
The aim of this research was to analyze the lubrication conditions of piston pin boss bearings used in the press-fit piston pins of automobile gasoline engines. An original pin boss friction measuring device was developed and used to successfully obtain measurements. It was revealed that the friction force peaks twice every cycle at high engine loads, and non-fluid lubrication characteristics are displayed. The friction forces for various differing piston pins and pin boss bearings were analyzed, and it was shown that reducing piston pin length or thickness to reduce piston weight, or reducing the pin boss bearing clearance to reduce noise worsen the friction characteristics and increase the possibility of abnormal bearing friction as well as seizure.
Technical Paper

Effect of Piston Motion on Piston Skirt Friction of a Gasoline Engine

1997-02-24
970839
This study has been aimed at the reduction of the intense piston skirt friction force that appears in the expansion stroke out of all piston friction forces generated in gasoline engines. The friction characteristics at the piston skirt have been analyzed according to the measured results at piston friction forces and the shapes of wears at the piston skirt in actual engine operations. It is found from the above that the majority of the side force working on each piston is supported by the oil film on the skirt, while only some of the side force is supported by the portion in metallic contact with the cylinder. It is also found through experiments that the metallic contact portion has a great effect on the friction force at the skirt. The effect of piston posture in expansion stroke on the friction force has been also analyzed based on the measured results of piston slap motions.
Technical Paper

Variation of Piston Friction Force and Ring Lubricating Condition in a Diesel Engine with EGR

1998-10-19
982660
Exhaust-gas recirculation (EGR) causes the piston rings and cylinder liners of a Diesel engine to suffer abnormal wear on the sliding parts. The present study aimed at making clear such abnormal wear structurally by examining the state of lubrication of the piston with a floating liner method, observing directly a visualized cylinder and experimenting on a Diesel engine for wear. As a result, it was confirmed that soot in EGR gas would change a lot the characteristics of the piston friction force. There are two mechanisms: one directly enters the sliding surfaces, and the other enters the ring rear, applying more load to them. It was also confirmed that the level of wear on the piston ring would vary to a large extent as the state of lubrication changed.
Technical Paper

The Effect of Oil Ring Geometry on Oil Film Thickness in the Circumferential Direction of the Cylinder

1998-10-19
982578
This paper describes measurements of oil film thickness of piston ring packages which have different oil control rings. The oil film thickness measurements were taken at three points, namely, the piston thrust side, front side and rear side, by the Laser Induced Fluorescence Method(LIF). One of the main findings is that the oil film thickness on the thrust side varies greatly from cycle to cycle, while cyclic variations are smaller on the front and rear sides. This difference is due to the smaller inclination of the oil control rings on the front and rear sides, compared with that on the thrust side. It is also found that oil consumption has a good correlation with oil film thickness on the thrust side and that the thrust side oil film thickness becomes thinner as the oil ring becomes narrower.
Technical Paper

Heat Transfer into Ceramic Combustion Wall of Internal Combustion Engines

1987-02-01
870153
A thin film thermocouple with a high accuracy was developed by means of computer analysis, which allowed measurements of instantaneous temperatures and heat fluxes on combustion chamber walls. Conventional Al-alloy and ceramic plates were compared in terms of the heat loss at the upper surface of each piston during combustion, using a gasoline engine and a diesel engine in the series of experiments. It was found by the comparison that the ceramic plates subjected to higher temperatures had greater heat losses in both the gasoline and diesel engines contrary to the anticipation.
Technical Paper

Effect of Fuel Properties of Biodiesel on Its Combustion and Emission Characteristics

2011-08-30
2011-01-1939
The use of biofuel is essential for the reduction of greenhouse gas emission. This paper highlights the use of biodiesel as a means of reducing greenhouse gas emission from the diesel engine of heavy-duty vehicles. Biodiesel is fatty acid methyl ester (FAME) obtained through ester exchange reaction by adding methanol to oil, such as rapeseed oil, soybean oil, palm oil, etc. The CO₂ emission from combustion of biodiesel is defined to be equivalent to the CO₂ volume absorbed by its raw materials or plants in their course of growth. On the other hand, however, biodiesel is known to increase the NOx emission when compared with operating with conventional diesel fuel, then suppressing this increase is regarded as a critical issue. This study is intended to identify the fuel properties of biodiesel free from increase in the NOx emission.
Technical Paper

Effect of Boiling Point Differences of Two-Component Normal Paraffin Fuels on Combustion and Emission in CI Engines

2003-03-03
2003-01-0757
The effect of boiling point difference as well as the flash boiling of two-component normal paraffin fuels on combustion and exhaust emission has been examined under different test conditions. To obtain a wide variation in boiling point between components different high boiling point fuels (n-undecane, n-tridecane and n-hexadecane) were blended with a low boiling point fuel (n-pentane) and different low boiling point fuels (n-pentane, n-hexane, and n-heptane) were blended with a high boiling point fuel (n-hexadecane). In addition the volume fraction of n-pentane was varied to have the best mixture ratio with n-tridecane. These fuel combinations exhibit different potential for flash boiling based on a certain ambient condition. The results indicate that though the potential for flash boiling is the highest for a mixture of n-pentane and n-hexadecane it emits about 20% higher PM than a mixture of n-pentane and n-tridecane.
Technical Paper

Optimization of Hydrogen Jet Configuration by Single Hole Nozzle and High Speed Laser Shadowgraphy in High Pressure Direct Injection Hydrogen Engines

2011-08-30
2011-01-2002
A new ignition-combustion concept named PCC (Plume Ignition Combustion Concept), which ignite rich mixture plume in the middle of injection period or right after injection of hydrogen is completed, is proposed by the authors in order to reduce NOx emissions in high engine load conditions with minimizing trade-offs on thermal efficiency. In this study fundamental requirements of hydrogen jet to optimize PCC are investigated by using single and multi-hole nozzle with a combination of high speed laser shadowgraphy to visualize propagating flame. As a result, it was infered that igniting the mixture plume in the middle of injection period with minimizing jet penetration to chamber wall is effective reducing NOx formation even further.
Technical Paper

Diesel Exhaust Simulator: Design and Application to Plasma Discharge Testing

2003-03-03
2003-01-1184
A diesel fuel and air diffusion flame burner system has been designed for laboratory simulation of diesel exhaust gas. The system consists of mass flow controllers and a fuel pump, and employs several unique design and construction features. It produces particulate emissions with size, number distribution, and morphology similar to diesel exhaust. At the same time, it generates NOx emissions and HC similar to diesel. The system has been applied to test plasma discharges. Different design discharge devices have been tested, with results indicating the importance of testing devices with soot and moisture. Both packed bed reactor and flat plate dielectric barrier discharge systems remove some soot from the gas, but the designs tested are susceptible to soot fouling and related electrical failures. The burner is simple and stable, and is suitable for development and aging of plasma and catalysts systems in the laboratory environment.
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