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This paper documents an extensive study aimed at a better understanding of the peculiarities and performance of crankshaft mounted gerotor pumps for IC engines lubrication. At different extents, the modelling, simulation and testing of a specific unit are all considered. More emphasis, at the modelling phase, is dedicated to the physical and mathematical description of the flow losses mechanisms; the often intricate aspects of kinematics being deliberately left aside. The pressure relief valve is analysed at a considerable extent as is the modelling of the working fluid, a typically aerated subsystem in such applications. Simulation is grounded on AMESim, a relatively novel tool in the fluid power domain, that proves effective and compliant with user deeds and objectives. Testing, at steady-state conditions, forms the basis for the pro!gressive tuning of the simulation model and provides significant insight into this type of volumetric pump.

Linear, crankless, internal combustion engines may find application in the generation of electrical power without the need to convert linear to rotary motion. The elimination of the connecting rod and crankshaft would significantly improve the efficiency of the engine and the reduced weight and cost is an added advantage. The case of two opposed cylinders, with two pistons linked by a solid rod, was considered for idealized modeling. The piston/rod assembly was considered to oscillate with only constant frictional drag. The Otto cycle was used to model efficiency, and this in turn determined compression ratio. Dimensionless groups governing the engine working were identified and used in formulating a description of the engine behavior. Two-stroke operation was assumed. Velocity and position can be related analytically to yield a phase plot.

The exhaust noise of a two-cylinder four-stroke diesel engine was experimentally investigated in order to examine the predictability of the exhaust noise to be reduced by a feedforward active control system. Special attention has been paid to the low frequency characteristics of the exhaust noise as low frequency noise is difficult to reduce with a conventional muffler but effective to control by active control technique. The periodicity of the exhaust noise was examined with the ensemble-average and ensemble-standard deviation of the exhaust pressure signals. The results showed that the exhaust noise investigated was basically quasi-periodic and its variation between cycles was acceptable with an adaptive control algorithm. The properties of the exhaust pressure in low frequency domain were analyzed with the spectra of the exhaust noise pressure.

The development of a modern internal combustion engine can be characterized by three main trends: durability increase, emission reduction, and fuel economy improvement. Ring pack design addresses all of these issues. The ring behavior affects the blow-by past the ring pack, the oil film left on the cylinder liner, the friction force between the liner and the ring, and the wear of the ring and the cylinder liner. In order to predict these phenomena, the prediction of inter-ring gas flow and ring behavior, especially ring motion and ring twist about ring centroid, is needed. This paper presents the results of the modeling of 3-dimensional ring twist and its influence on ring performance and blow-by. The TWIST program includes a 3-dimensional beam model of a piston ring.

In this paper, a generic methodology is proposed to simulate the static and dynamic responses of a SI gas engine. The predicted simulation of engine performances is based on a one zone thermodynamic model. The turbocharger is modeled by using polytropic coefficients, the intercooler by its efficiency. The Ventury effect carburetor model is based on physic properties and the butterfly valve model uses a classical approach. A comparison between the simulation and experimental results is realized in terms of static and dynamic performances in closed loop. Comparisons with actual data obtained on a 210 kW engine shows that the maximum error is less than 5 %.

Motor vehicles emissions regulations become more and more stringent, concerning the air quality improvement. In that way, EGR technology ( like Exhaust Gas Recirculation ), with increasing recirculation flowrates, is more and more frequently applied [3]. If the manifold is made in polymer composites, problems appear at the EGR interface, because of material T° limits ( between 150° and 180 °C stabilized ). The study presents different goals: 1. To identify the major parameters leading to high manifold heat constraints; 2. To model the phenomena, to be able to extrapolate experimental results; 3. To get a practical tool, under abacus and model, helping designers to know the limits of the design, for one application, and so that, to be sure that the manifolds will not be overstressed in service. To get this, both experimental and numerical ways are taking into account. Let us remind that EGR is applied to limit NOx levels, and also fuel consumption by pumping losses limitation [3].

Engine tests were conducted to study the effect of fuel-air mixture preparation on the combustion and emission performance of a two-stroke direct-injection engine. The in-cylinder mixture distribution was altered by changing the injection system, injection timing, and by substituting the air in an air-assisted injector with nitrogen. Two injection systems which produce significantly different mixtures were investigated; an air-assisted injector with a highly atomized spray, and a single-fluid high pressure-swirl injector with a dense penetrating spray. The engine was operated at overall A/F ratios of 30:1, where stratification was necessary to ensure stable combustion; and at 20:1 and 15:1 where it was possible to operate in a nearly homogeneous mode. Moderate engine speeds and loads were investigated. The effects of the burning-zone A/F ratio were isolated by using nitrogen as the working fluid in the air-assist injector.

The schlieren visualization of in-cylinder processes from the side of an engine cylinder is useful to understand the phenomena which change along the cylinder axis. A transparent collimating cylinder, TCC, permits schlieren observation inside the cylinder through its transparent wall. In this study, a single cylinder visualization engine with the TCC was applied to a direct-injection gasoline engine. A fuel spray, mixture formation and combustion were observed with a simultaneous measurement of in-cylinder pressure. The shape of the fuel spray and subsequent mixture formation process are drastically changed with the injection timing. The images of luminous flame were also taken with the schlieren images during the combustion period. Stable combustion, misfire and abnormal combustion are discussed with the comparison between the observed results and in-cylinder pressure analysis.

An experimental study was carried out to investigate the effects of fuel injection timing on the spatial and temporal development of injected fuel sprays within a firing direct-injection spark-ignition (DISI) engine. It was found that the structure of the injected fuel sprays varied significantly with the timing of the injection event. During the induction stroke and the early part of the compression stroke, the development of the injected fuel sprays was shown to be controlled by the state of the intake and intake-generated gas flows at the start of injection (SOI).The relative influence of these two flow regimes on the injected fuel sprays during this period was also observed to change with injection timing, directly affecting tip penetration, spray/wall impingement and air-fuel mixing. Later in the compression stroke, the results show the development of the injected fuel sprays to be dominated by the increased cylinder pressure at SOI.

The purpose of this work was to investigate the influence of fuel parameters on emissions, combustion and cycle to cycle IMEP variations in a single cylinder version of a commercial direct injection stratified charge (DISC) spark ignition engine. The emission measurements employed both conventional emission measurement equipment as well as on-line gas chromatography/mass spectrometry (GC/MS). Four different fuels were compared in the study. The fuel parameters that were studied were distillation range and MTBE (Methyl Tert Buthyl Ether) content. A European certification gasoline fuel was used as a reference. The three other fuels contained 10% MTBE. The measurements were performed at a low engine speed and at a low, constant load. The engine was operated in stratified mode. The start of injection was altered 15 crankangle degrees before and after series calibration with fixed ignition timing in order to vary mixture preparation time.

Lean burn engines now being developed employ in-cylinder injection which requires high pressures and so necessitates expensive injection equipment. The experiments reported here used air assisted in-cylinder injection, and injected a mixture of air and fuel during the intake stroke, so allowing atomization at lower injection pressures than those necessary in compressing fuel with solid injection. The experiments confirmed that operation in this manner resulted in similar output and fuel consumption as with a carburetor. Next, a divided combustion chamber was installed and connected to the main combustion chamber and air assisted in-cylinder injection from a reed type injection nozzle was attempted. With this arrangement, stable idling operation was possible to air-fuel ratios (A/F) of 70. Lean burn at A/F = 22 to 35 was also achieved at maximum rated outputs (3.7 kW at 4200 min-l) of 6 - 18 %.

A study to investigate the influence of fuel injection timing on exhaust emissions from a single-cylinder direct-injection spark-ignition (DISI) research engine was performed. Experimental results were obtained for carbon monoxide (CO), unburned hydrocarbon (HC), and oxides of nitrogen (NOx). Images showing the variation of liquid-phase fuel distribution with changing injection timing were obtained in a firing optically-accessed engine of similar design. A correlation between measured emissions and observed liquid-phase fuel distribution was performed. This correlation was supported by development of phenomenological models that permit explanation of the variation of CO, HC, and NOx emissions with changes in air-fuel mixture preparation.

Two-dimensional pulse-laser Mie scattering visualization of the direct-injection gasoline fuel sprays and wall impingement processes was carried out inside a single-cylinder optically accessible engine under motoring condition. The injectors have been first characterized inside a pressurized chamber using identical technique, as well as high-speed microscopic visualization and phase Doppler measurement techniques. The effects of injector cone angle, location, and injection timings on the wall impingement processes were investigated. It was found that the fuel vaporization is not complete at the constant engine speed tested. Fuel spray droplets were observed to disperse wider in the motored engine when compared with an isothermal quiescent ambient conditions. The extent of wall-impingement varies significantly with the injector mounting position and spray cone angle; however, its effect can be reduced to some extent by optimizing the injection timing.

Meeting future exhaust emission and fuel consumption standards for passenger cars will require refinements in how the combustion process is carried out in spark ignition engines. A direct injection system reduces fuel consumption under road load cruising conditions, and stratified charge of the air-fuel mixture is particularly effective for lean combustion. This paper describes an approach to improve combustion stability for direct fuel injection gasoline engines. Effects of spray characteristics (spray pattern and diameter) and air flow motion on the combustion stability were investigated. Spray patterns were observed by the laser sheet scattering method and 3-dimensional laser doppler velocimetry. Mixture behavior in the combustion chamber was observed by the laser-induced fluorescence method using an excimer laser and single cylinder optical engine. It was found that the spray pattern for a pressurized condition affects the combustion stability and smoke generation.

Data from two engines with distinct stratified-charge combustion systems are presented. One uses an air-forced injection system with a bowl-in-piston combustion chamber. The other is a liquid-only, high-pressure injection system which uses fluid dynamics coupled with a shaped piston to achieve stratification. The fuel economy and emission characteristics were very similar despite significant hardware differences. The contributions of indicated thermal efficiency, mechanical friction, and pumping work to fuel economy are investigated to elucidate where the efficiency gains exist and in which categories further improvements are possible. Emissions patterns and combustion phasing characteristics of stratified-charge combustion are also discussed.

The present paper examines the possibility of chemical treatment of old catalysts (a catalyst that has exceeded exhaust limits) for the purpose of improving catalytic efficiency. The proposed method inserts the catalyst in a bath of a strong organic solvent that dissolves oil, soot and fuel residues cleaning the active surface of the catalyst. The preliminary experimental results based on CO, HC and catalyst inlet-outlet temperature difference measurements indicate that after this treatment the catalytic efficiency improves considerably (>30%). Therefore, there are strong indications that if car catalysts underwent a similar treatment at regular service intervals, for example, engine emissions could be considerably reduced and catalyst operational life extended. However more tests under variable engine speed (FTP-test) and load are clearly required in the future, before a definite conclusion can be made.

To clarify the thermal deterioration mechanism of three-way catalysts quantitatively, we investigated the relationship between the catalytic performance and the catalyst characteristics for thermally aged Pt/Rh catalysts. 1. Experimentally, the HC oxidation reaction, which occurs on the surface of Pt/Rh particles on catalysts, is approximated by a first-order reaction of HC concentration with a constant activation energy. 2. The relationship between the Pt mean diameter D and the HC 50% conversion temperature T50 is described by the following equation; where E and kB are the activation energy of the reaction and the Boltzman constant, respectively. 3. The sintering rate of Pt particles on the three-way catalysts was found to depend on the aging temperature(T) of catalyst and the concentration of oxygen in the gas phase([O2]).

In this paper the behavior of the three-way catalyst equipping a 2-liter car is fully analyzed considering exhaust gas and ceramic temperatures trends ( and of related engine parameters) in on-road operations of the car under different traffic conditions. These are classified by means of driving cycles clusters determined by multivariate statistical analysis of car speed and gear usage real profiles, detected on-road by the same car in designed experimental plans. Instantaneous fuel consumption and signals of a linear oxygen sensor, placed up-stream catalyst, have been analyzed to better characterize engine and catalyst performance. Emissions are measured in laboratory performing the most statistically representative driving cycles with car on the dynamometer chassis. The effect of traffic conditions on catalyst behavior and exhaust emissions is analyzed through the study of series of consecutive driving cycles.

The exhaust emissions of two stroke vehicles like motorbikes and scooters contribute to the pollution in urban areas of developing countries in South East Asia and India to a major extent. But also in Japan and selected European countries exhaust gas limitations become effective from 10/1998 and 06/1999 for these vehicles. To control this emissions catalytic aftertreatment by Hot Tubes® and/or monolith type catalysts are applied. Due to the constant rich operation of the two-stroke engines, common design criteria for three-way catalysts fail. Extremely high exhaust gas hydrocarbon concentrations lead to high exotherms during oxidation which increases the exhaust gas temperature to a range between 800 and 900 °C. Furthermore the lack of oxygen limits the CO and HC oxidation under certain engine operation conditions. Therefore, water-gas shift and steam reforming reactions play an important part in catalytic aftertreatment of two-stroke exhausts.

We purchased an assortment of retail aftermarket gasoline additives from many manufacturers with the intention of evaluating the contents to compare the active ingredients available in the package with the product performance and benefit claims as advertised on the label. We did an initial screening to determine a gross actives level through a low temperature non-volatile matter determination. We then sorted the products into groups according to their type of claim. Further infrared spectrographic analysis determined chemical content and confirmed the initial quantitative work. This information let us determine whether the manufacturer's choice of active ingredients was appropriate to provide the particular benefits claimed and whether there was enough to do the job.