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Technical Paper

Evaluation Between Engine Stop/Start and Cylinder Deactivation Technologies Under Southeast Asia Urban Driving Condition

Engine stop/start and cylinder deactivation are increasingly in use to improve fuel consumption of internal combustion engine in passenger cars. The stop/start technology switches off the engine to whenever the vehicle is at a stand-still, typically in a highly-congested area of an urban driving. The inherent issue with the implementation of stop/start technology in Southeast Asia, with tropical climate such as Malaysia, is the constant demand for the air-conditioning system. This inevitably reduces the duration of engine switch-off when the vehicle at stop and consequently nullifying the benefit of the stop/start system. On the other hand, cylinder deactivation technology improves the fuel consumption at certain conditions during low to medium vehicle speeds, when the engine is at part load operation only. This study evaluates the fuel economy benefit between the stop/start and cylinder deactivation technologies for the actual Kuala Lumpur urban driving conditions in Malaysia.
Technical Paper

Engine Operational Benefits with Cylinder Deactivation in Malaysian Urban Driving Conditions

Cylinder deactivation has been utilized by vehicle manufacturers since the 80's to improve fuel consumption and exhaust emissions. Cylinder deactivation is achieved by cutting off fuel supply and ignition in some of the engine cylinders, while their inlet and outlet valves are fully closed. The vehicle demand during cylinder deactivation is sustained by only the firing cylinders, hence increasing their indicated power. Conventionally, half the number of cylinders are shut at certain driving conditions, which normally at the lower demand regime. An optimal strategy will ensure cylinder deactivation contributes to the fuel saving without compromising the vehicle drivability. Cylinder deactivation has been documented to generally improve fuel consumption between 6 to 25 %, depending on the type-approval test drive cycle. However, type-approval test has been reported to differ from the “real-world” fuel consumption values.
Technical Paper

Characterisation of Diesel Engine Transient Pumping-loss and Control Methodology for Transient Specific Fuel Consumption (SFC)

This study measures, during various transients of speed and load, in-cylinder-, intake-/exhaust- (manifold) pressures and engine torque. The tests were conducted on a typical high power-density, passenger car powertrain (common-rail diesel engine, of in-line 4-cylinder configuration equipped with a Variable Geometry Turbocharger). The objective was to quantify the deterioration (relative to a steady-steady condition) in transient Specific Fuel Consumption (SFC) that may occur during lagged-boost closed-loop control and thus propose an engine control strategy that minimises the transient SFC deterioration. The results, from transient characterisation and the analysis method applied in this study, indicate that transient SFC can deteriorate up to 30% (function of load transient) and is primarily caused by excessive engine pumping-loss.
Technical Paper

Efforts to Establish Malaysian Urban Drive-Cycle for Fuel Economy Analysis

Emissions from motor vehicles are known to be the major contributor of air pollution. Pollutants that are commonly concerned and regulated for petrol engines are Hydrocarbons, Carbon Monoxide, Nitrogen Oxides and Particulate Matter. One of the most important factor that vary these pollutants is the engine operating condition such as cold start, low engine loads and high engine loads which are found during actual driving. In actual driving conditions, particularly in urban areas, vehicles regularly travel at idle, low or medium speeds which signify the engine part load operations. Thus urban driving carries a crucial weight on the overall vehicle fuel economy. Understanding the implications of urban driving conditions on fuel economy will allow for strategic application of key technologies such as cylinder deactivation in the efforts towards better efficiency.
Technical Paper

Turbocharger Matching Method for Reducing Residual Concentration in a Turbocharged Gasoline Engine

In a turbocharged engine, preserving the maximum amount of exhaust pulse energy for turbine operation will result in improved low end torque and engine transient response. However, the exhaust flow entering the turbine is highly unsteady, and the presence of the turbine as a restriction in the exhaust flow results in a higher pressure at the cylinder exhaust ports and consequently poor scavenging. This leads to an increase in the amount of residual gas in the combustion chamber, compared to the naturally-aspirated equivalent, thereby increasing the tendency for engine knock. If the level of residual gas can be reduced and controlled, it should enable the engine to operate at a higher compression ratio, improving its thermal efficiency. This paper presents a method of turbocharger matching for reducing residual gas content in a turbocharged engine.
Technical Paper

Experimental Efficiency Characterization of an Electrically Assisted Turbocharger

Electrically assisted turbochargers consist of standard turbochargers modified to accommodate an electric motor/generator within the bearing housing. Those devices improve engine transient response and low end torque by increasing the power delivered to the compressor. This allows a larger degree of engine down-sizing and down-speeding as well as a more efficient turbocharger to engine match, which translates in lower fuel consumption. In addition, the electric machine can be operated in generating mode during steady state engine running conditions to extract a larger fraction of the exhaust energy. Electric turbocharger assistance is therefore a key technology for the reduction of fuel consumption and CO2 emissions. In this paper an electrically assisted turbocharger, designed to be applied to non-road medium duty diesel engines, is tested to obtain the turbine and electrical machine efficiency characteristics.
Technical Paper

The Sensitivity of Transient Response Prediction of a Turbocharged Diesel Engine to Turbine Map Extrapolation

Mandated pollutant emission levels are shifting light-duty vehicles towards hybrid and electric powertrains. Heavy-duty applications, on the other hand, will continue to rely on internal combustion engines for the foreseeable future. Hence there remain clear environmental and economic reasons to further decrease IC engine emissions. Turbocharged diesels are the mainstay prime mover for heavy-duty vehicles and industrial machines, and transient performance is integral to maximizing productivity, while minimizing work cycle fuel consumption and CO2 emissions. 1D engine simulation tools are commonplace for “virtual” performance development, saving time and cost, and enabling product and emissions legislation cycles to be met. A known limitation however, is the predictive capability of the turbocharger turbine sub-model in these tools.
Technical Paper

Effects of Valve Deactivation on Thermal Efficiency in a Direct Injection Spark Ignition Engine under Dilute Conditions

Reported in the current paper is a study into the cycle efficiency effects of utilising a complex valvetrain mechanism in order to generate variable in-cylinder charge motion and therefore alter the dilution tolerance of a Direct Injection Spark Ignition (DISI) engine. A Jaguar Land Rover Single Cylinder Research Engine (SCRE) was operated at a number of engine speeds and loads with the dilution fraction varied accordingly (excess air (lean), external Exhaust Gas Residuals (EGR) or some combination of both). For each engine speed, load and dilution fraction, the engine was operated with either both intake valves fully open - Dual Valve Actuation (DVA) - or one valve completely closed - Single Valve Actuation (SVA) mode. The engine was operated in DVA and SVA modes with EGR fractions up to 20% with the excess air dilution (Lambda) increased (to approximately 1.8) until combustion stability was duly compromised.
Journal Article

An Investigation of Deformation Effects on Phase Transformation in Hot Stamping Processes

To reduce the fuel consumption as well as to improve the crash safety of vehicles, the usage of hot stamping parts is increasing dramatically in recent years. Aisin Takaoka has produced hot stamping parts since 2001 and has developed various technologies related to Hot Stamping. In an actual hot stamping process, parts with insufficient strength could be produced sometimes at a prototyping phase, even under the proper forming conditions. In order to understand these phenomena, in this paper, phase transformation in a boron steel 22MnB5 under various cooling rates were investigated and the effects of pre-strain conditions on the phase transformations were characterised. Uniaxial tensile specimens were stretched under isothermal conditions to different strain levels of 0-0.3, at strain rates of 0.1-5.0/s and deformation temperatures of 650-800°C.
Journal Article

Ultra Boost for Economy: Extending the Limits of Extreme Engine Downsizing

The paper discusses the concept, design and final results from the ‘Ultra Boost for Economy’ collaborative project, which was part-funded by the Technology Strategy Board, the UK's innovation agency. The project comprised industry- and academia-wide expertise to demonstrate that it is possible to reduce engine capacity by 60% and still achieve the torque curve of a modern, large-capacity naturally-aspirated engine, while encompassing the attributes necessary to employ such a concept in premium vehicles. In addition to achieving the torque curve of the Jaguar Land Rover naturally-aspirated 5.0 litre V8 engine (which included generating 25 bar BMEP at 1000 rpm), the main project target was to show that such a downsized engine could, in itself, provide a major proportion of a route towards a 35% reduction in vehicle tailpipe CO2 on the New European Drive Cycle, together with some vehicle-based modifications and the assumption of stop-start technology being used instead of hybridization.
Technical Paper

Adaptive Turbo Matching: Radial Turbine Design Optimization through 1D Engine Simulations with Meanline Model in-the-Loop

Turbocharging has become the favored approach for downsizing internal combustion engines to reduce fuel consumption and CO2 emissions, without sacrificing performance. Matching a turbocharger to an engine requires a balance of various design variables in order to meet the desired performance. Once an initial selection of potential compressor and turbine options is made, corresponding performance maps are evaluated in 1D engine cycle simulations to down-select the best combination. This is the conventional matching procedure used in industry and is ‘passive’ since it relies on measured maps, thus only existing designs may be evaluated. In other words, turbine characteristics cannot be changed during matching so as to explore the effect of design adjustments. Instead, this paper presents an ‘adaptive’ matching methodology for the turbocharger turbine.
Technical Paper

Steady-State, Transient and WLTC Drive-Cycle Experimental Performance Comparison between Single-Scroll and Twin-Scroll Turbocharger Turbine

The use of twin-scroll turbocharger turbine in automotive powertrain has been known for providing better transient performance over conventional single-scroll turbine. This has been accredited to the preservation of exhaust flow energy in the twin-scroll volute. In the current study, the performance comparison between a single and twin-scroll turbine has been made experimentally on a 1.5L passenger car gasoline engine. The uniqueness of the current study is that nearly identical engine hardware has been used for both the single and twin-scroll turbine volutes. This includes the intake and exhaust manifold geometry, turbocharger compressor, turbine rotor and volute scroll A/R variation trend over circumferential location. On top of that, the steady-state engine performance with both the volutes, has also been tuned to have matching brake torque.