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Fork system is a primary component for motorcycles because it assures the contact between tires and road, therefore the safety and the driving feeling. Usually fork optimization and tuning are experimentally made involving the generation of a high large number of prototypes and an expensive experimental campaign. To reduce the design and the tuning phases of a generic damper system, the numerical simulation should be considered. In this paper, a one-dimensional (1D) model of fore-carriage forks for road applications is presented. The model was built-up in AMESim code. In particular, the authors’ attention was focused on the detection and analysis of cavitation phenomenon inside the fork. As well known, the cavitation is a complex three-dimensional (3D) phenomenon that implies the phase transition.

Characteristics of soot deposits in the EGR cooler were studied, on basis of which a comprehensive model for soot particle depositions was developed. It was found that the soot deposit may be divided into three characteristic layers: a quasi-crystal base layer formed by nano-particles, an intermediate layer of denser packing of soot particles with meso pores, and a highly porous top layer formed by mechanical interlocking of soot particles. The cooler performance is affected significantly by the top layer of the deposit. Because of their weak contact energy, particles in the top layer and intermediate layers may be removed by the shear force under high EGR flows. The contact energy for the particles in the base layer is much stronger than that in the surface and intermediate layers. The base layer may be removed only with physicochemical methods.

Engine-out HC emissions from a PFI spark ignition engine were measured using a gas chromatograph and a flame ionization detector (FID). Two port fuel injectors were used respectively for ethanol and gasoline so that the delivered fuel was comprised of 0, 25, 50, 75 and 100% (by volume) of ethanol. Tests were run at 1.5, 3.8 and 7.5 bar NIMEP and two speeds (1500 and 2500 rpm). The main species identified with pure gasoline were partial reaction products (e.g. methane and ethyne) and aromatics, whereas with ethanol/gasoline mixtures, substantial amounts of ethanol and acetaldehyde were detected. Indeed, using pure ethanol, 74% of total HC moles were oxygenates. In addition, the molar ratio of ethanol to acetaldehyde was determined to be 5.5 to 1. The amount (as mole fraction of total HC moles) of exhaust aromatics decreased linearly with increasing ethanol in the fuel, while oxygenate species correspondingly increased.

With a high thermal efficiency and low CO2 (carbon dioxide) emissions, Diesel engines become leader of transport market. However, the exhaust-gas legislation evolution leads to a drastic reduction of NOx (nitrogen oxide) standards with very low particulate, HC (unburned hydrocarbons) and CO (carbon monoxide) emissions, while combustion noise and fuel consumption must be kept under control. The reduction of the volumetric compression ratio (CR) is a key factor to reach this challenge, but it is today limited by the capabilities to provide acceptable performances during very cold operation: start and idle below −10°C. This paper focuses on the understanding of the main parameter’s impacts on cold operation. Effects of parameters like hardware configuration and calibration optimization are investigated on a real 4 cylinder Diesel 14:1 CR engine, with a combination of specific advanced tools.

Fuel wall impingement commonly occurs in small-bore diesel engines. Particularly during engine starting, when wall temperatures are low, the evaporation rate of fuel film remaining from previous cycles plays a significant role in the autoignition process that is not fully understood. Pre-injection chemiluminescence (PIC), resulting from low-temperature oxidation of evaporating fuel film and residual gases, was measured over 3200 μsec intervals at the end of the compression strokes, but prior to fuel injection during a series of starting sequences in an optical diesel engine. These experiments were conducted to determine the effect of this parameter on combustion phasing and were conducted at initial engine temperatures of 30, 40, 50 and 60°C, at swirl ratios of 2.0 and 4.5 at 1000 RPM. PIC was determined to increase and be highly correlated with combustion phasing during initial cycles of the starting sequence.

Low temperature combustion is a promising way to reach low NOx emissions in Diesel engines but one of its drawbacks, in comparison to conventional Diesel combustion is the drastic increase of Unburned Hydrocarbons (UHC). In this study, the sources of UHC of a low temperature combustion system were investigated in both a standard, all-metal single-cylinder Diesel engine and an equivalent optically-accessible engine. The investigations were conducted under low load operating conditions (2 and 4 bar IMEP). Two piston bowl geometries were tested: a wall-guided and a more conventional Diesel chamber geometry. Engine parameters such as the start of injection (SOI) timing, the level of charge dilution via exhaust gas re-circulation (EGR), intake temperature, injection pressure and engine coolant temperature were varied. Furthermore, the level of swirl and the diameter of the injector nozzle holes were also varied in order to determine and quantify the sources of UHC.

A 2005 prototype diesel aftertreatment system consisting of diesel oxidation catalysts (DOC), Cu/zeolite Selective Catalytic Reduction (SCR) catalyst, and Catalyzed Diesel Particulate Filter (CDPF) was aged to an equivalent of 120k mi on an engine dynamometer using an aging cycle that incorporated both city and highway driving modes. The program demonstrated durable reduction in particulate matter (PM) and nitrogen oxides (NOx) emissions to federal Tier 2 levels on a 6000 lbs light-duty truck application. Very low sulfur diesel fuel (∼15 ppm) enabled lower PM emissions, reduced the fuel penalty associated with the emission control system, and improved long-term system durability. A total of 643 filter regenerations occurred during the aging that raised the entire catalyst system to high temperatures on a regular basis. After testing the aged system on a 6000 lbs light-duty diesel truck, a post mortem analysis was completed on core samples taken from the DOC, SCR catalyst, and filter.

Gasoline Homogeneous Charge Compression Ignition (HCCI) combustion has been studied widely in the past decade. However, in HCCI engines using negative valve overlap (NVO), there is still uncertainty as to whether the effect of pilot injection during NVO on the start of combustion is primarily due to heat release of the pilot fuel during NVO or whether it is due to pilot fuel reformation. This paper presents data taken on a 4-cylinder gasoline direct injection, spark ignition/HCCI engine with a dual cam system, capable of recompressing residual gas. Engine in-cylinder samples are extracted at various points during the engine cycle through a high-speed sampling system and directly analysed with a gas chromatograph and flame ionisation detector. Engine parameter sweeps are performed for different pilot injection timings and quantities at a medium load point.

The effects of spray targeting on mixing, combustion, and pollutant formation under a low-load, late-injection, low-temperature combustion (LTC) diesel operating condition are investigated by optical engine measurements and multi-dimensional modeling. Three common spray-targeting strategies are examined: conventional piston-bowl-wall targeting (152° included angle); narrow-angle floor targeting (124° included angle); and wide-angle piston-bowl-lip targeting (160° included angle). Planar laser-induced fluorescence diagnostics in a heavy-duty direct-injection optical diesel engine provide two-dimensional images of fuel-vapor, low-temperature ignition (H2CO), high-temperature ignition (OH) and soot-formation species (PAH) to characterize the LTC combustion process.

This study presents emission results measured with renewable and synthetic diesel fuels. Three engines and five city buses were studied. The efficiency of diesel oxidation catalyst combined to particle oxidation catalyst (POC®) was measured with two engines. The studied diesel fuels were EN590, FAME, HVO and GTL. In most cases all regulated emissions decreased with HVO and GTL fuels compared to conventional EN590 diesel fuel. With FAME, the NOx emissions were higher compared to EN590, but other emissions were reduced. Alternative fuels had a positive effect on emissions, which are considered harmful to human health.

Rapeseed oil methyl ester, two common fuels and one artificial blend were investigated their effects on particulate emissions. A heavy-duty diesel engine equipped with a diesel oxidation catalyst (DOC) was used for this test. Properties such as composition of particulate matter, as well as particle size and number distributions were measured using an electronic low pressure impactor (ELPI) and a scanning mobility particle sizer (SMPS) besides the regulated emissions: carbon monoxide (CO), hydrocarbons (HC), nitrogen oxides (NOx), and particulate matter (PM). Furthermore investigations were carried out regarding the influence of dilution temperature on particle number distribution measured via SMPS. Studies were carried out with and without a DOC. Additionally the mutagenic potency of the particulate and gaseous emissions was determined using the Ames test. RME led to lower regulated emissions than common diesel fuel with exception of NOx.

The CRC Fuels for Advanced Combustion Engines working group has worked to identify a matrix of research diesel fuels for use in advanced combustion research applications. Nine fuels were specified and formulated to investigate the effects of cetane number aromatic content and 90% distillation fraction. Standard ASTM analyses were performed on the fuels as well as GC/MS and1H/13C NMR analyses and thermodynamic characterizations. Details of the actual results of the fuel formulations compared with the design values are presented, as well as results from standard analyses, such as heating value, viscosity and density. Cetane number characterizations were accomplished by using both the engine method and the Ignition Quality Tester (IQT™) apparatus.

The paper brings to evidence critical issues in the design of variable displacement vane pump controls for ICE lubrication. Tight packaging, high rotational speed and variable pressure setting are key aspects influencing the selection of pump geometric parameters as well as its displacement controls. A specific layout, where the pump displacement control is carried out by two linear actuators and a two-way pilot control valve, has been analysed. The paper focuses on the dimensioning of the front areas of the actuators considering two kinematic solutions, linear and rotational, for the external ring. Through a simulation model, validated by experimental tests, the influence of different pressure control strategies on the dimensioning has been investigated.

Life-cycle assessments (LCA) of biodistillate fuels are becoming increasingly important for policy decisions regarding alternative fuels. However, due to the data-intensive and assumptive nature of LCAs, rarely do two different studies produce comparable results. To add to the complexity, effects of indirect land use changes are now being incorporated into LCA models. This development is influencing policy decisions and generating much controversy. A literature survey of 55 different LCA studies of bio-distillate fuels was conducted. The comparison of energy requirements and global warming potential (GWP) impacts of these studies help to illustrate which data inputs and assumptions most strongly affect the results, and wherein the major discrepancies lie. Life-cycle energy results are typically reported as energy return (ER), meaning the heating value of the biofuel divided by the total fossil energy inputs to produce the fuels.

Biodistillate transportation fuels include biodiesel (produced via transesterification of animal fats and vegetable oils) and renewable diesel (produced via catalytic hydroprocessing of the same feedstocks). Production and use of biodistillates are increasing dramatically, both in the U.S. and globally. This paper describes the policy drivers prompting growth of biodistillate fuels in the U.S., Europe, and selected other countries. Trends in fuel production volumes and feedstocks supplies are presented for these fuels. Current feedstocks are dominated by soybean oil in the U.S. and rapeseed oil in Europe. However, there is much interest in developing alternative, non-edible feedstocks such as jatropha and microalgae. Currently, biodiesel is the dominant biodistillate in use, though interest in renewable diesel is increasing. This paper describes different conversion processes used to manufacture these fuels, and discusses the pros and cons of each.

The use of Variable Valve Actuation (VVA) systems offers many advantages in terms of increased engine power, reduced fuel consumption and pollutant emissions, accomplishing a significant improvement of the global efficiency of the engine. In the last decade different devices have been proposed to implement advanced and innovative VVA managements on four-stroke engines. ElectroMechanical Valve Actuator (EMVA) formed by two opposite magnets and two balanced springs seem to be a very promising solution among several camless actuation systems. This type of valve actuator is characterized by highly nonlinear and strongly coupled dynamics which makes very difficult to govern engine valve motion during the last part of the closing and opening strokes, where an unstable behavior is exhibited. In this regard the control problem of the EMVA is tackled in this paper.

Evaluation of MFB50 is very useful for combustion control, since it gives an evaluation of the combustion process effectiveness. Real-time monitoring its value enables to detect for example the kind of combustion that is taking place (useful for example for HCCI applications), or could provide important information to improve real-time combustion control. While it is possible to determine the position where the 50% of mass burned inside the cylinder is reached using an in-cylinder pressure sensor, this work proposes to obtain this information from the engine speed fluctuation measurement. In-cylinder pressure sensors in fact are still not so common for on-board applications, since their cost will constitute an important portion of the whole engine control system cost.

A simultaneous multi-composition analyzing (SMCA) resonance enhanced multi-photon ionization (REMPI) system was used to investigate gasoline engine exhaust. Observed peaks for exhaust were smaller mass numbers than those from diesel exhaust. However, large species up to three ring aromatics were observed suggesting that soot precursor forms even in the gasoline engine. At low catalyst temperature condition, the reduction efficiencies of a three-way catalyst were higher for higher mass numbers. This result indicates that the larger species accumulate in the catalyst or elsewhere due to their lower vapor pressures. To evaluate the emission of low volatility species, the accumulation should be taken into account. In the hot mode, reduction efficiencies for aromatic species of three-way catalyst were almost 99.5% however, they fall to 70% in the cold start condition.

When increasing EGR from low levels to a level that corresponds to low temperature combustion, soot emissions initially increase due to lower soot oxidation before decreasing to almost zero due to very low soot formation. At the EGR level where soot emissions start to increase, the NOx emissions are low, but not sufficiently low to comply with future emission standards and at the EGR level where low temperature combustion occurs CO and HC emissions are too high. The purpose of this study was to investigate the possibilities for shifting the so-called soot bump (where soot levels are increased) to higher EGR levels, or to reduce the magnitude of the soot bump using very high injection pressures (up to 240 MPa) while reducing the NOx emissions using EGR. The possibility of reducing the CO and HC emissions at high EGR levels due to the increased mixing caused by higher injection pressure was also investigated and the flame was visualized using an endoscope at chosen EGR values.

Unique silver/alumina catalysts developed in collaboration with BASF Corporation were investigated at General Motors under simulated lean-burn engine exhaust feed conditions for the selective catalytic reduction of NOx using hydrocarbons as reductant (HC-SCR). Catalysts were evaluated using a laboratory fixed-bed flow reactor system over a wide range of temperatures relevant to light-duty and heavy-duty exhaust conditions for CIDI (compression ignition direct injection – diesel) and SIDI (spark ignition direct injection – gasoline) applications. This report investigates the effects of silver content (i.e., wt.% Ag2O) and reductant composition (i.e., simulated diesel fuel, simulated gasoline, ethanol, and ethanol/simulated gasoline mixtures) on the steady-state NOx reduction activity. A dual catalyst approach using a HC-SCR catalyst followed by an NH3-SCR catalyst was also investigated.