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Technical Paper

Parametric Study into the Effects of Factors Affecting Real-World Vehicle Exhaust Emission Levels

2007-04-16
2007-01-1084
The work presented investigates the effect of road gradient, head-wind, horizontal road curvature, changes in tyre rolling radius, vehicle drag co-efficient and vehicle weight on real-world emission levels of a modern EURO-IV vehicle. A validated steady-state engine performance map based vehicle modeling approach has been used for the analysis. The results showed that a generalized correction factor to include the effect of road-gradient on real-world emission levels might not yield accurate results, since the emission levels are strongly dependent on the position of the vehicle operating parameters on the engine maps. In addition, it also demonstrated that the inclusion of horizontal road curvature such as roundabouts and traffic islands are essential for the estimation of the real-world emission levels.
Technical Paper

Low Power Autoselective Regeneration of Monolithic Wall Flow Diesel Particulate Filters

2009-06-15
2009-01-1927
This paper presents research into a novel autoselective electric discharge method for regenerating monolithic wall flow diesel particulate filters using low power over the entire range of temperatures and oxygen concentrations experienced within the exhaust systems of modern diesel engines. The ability to regenerate the filter independently of exhaust gas temperature and composition significantly reduces system complexity compared to other systems. In addition, the system does not require catalyst loading and uses only mass- produced electronic and electrical components, thus reducing the cost of the after-treatment package. Purpose built exhaust gas simulation test rigs were used to evaluate, develop and optimise the autoselective regeneration system. On-engine testing demonstrated the performance of the autoselective regeneration process under real engine conditions.
Technical Paper

In-Cylinder Flow Structure Analysis by Particle Image Velocimetry Under Steady State Condition

2012-09-24
2012-01-1975
This paper deals with experimental investigations of the in-cylinder flow structures under steady state conditions utilizing Particle Image Velocimetry (PIV). The experiments have been conducted on an engine head of a pent-roof type (Lotus) for a number of fixed valve lifts and different inlet valve configurations at two pressure drops, 250mm and 635mm of H2O that correlate with engine speeds of 2500 and 4000 RPM respectively. From the two-dimensional in-cylinder flow measurements, a tumble flow analysis is carried out for six planes parallel to the cylinder axis. In addition, a swirl flow analysis is carried out for one horizontal plane perpendicular to the cylinder axis at half bore downstream from the cylinder head (44mm). The results show the advantage of using the planar technique (PIV) for investigating the complete flow structures developed inside the cylinder.
Technical Paper

Analytical Evaluation of Fitted Piston Compression Ring: Modal Behaviour and Frictional Assessment

2011-05-17
2011-01-1535
Piston compression rings are thin, incomplete circular structures which are subject to complex motions during a typical 4-stroke internal combustion engine cycle. Ring dynamics comprises its inertial motion relative to the piston, within the confine of its seating groove. There are also elastodynamic modes, such as the ring in-plane motions. A number of modes can be excited, dependent on the net applied force. The latter includes the ring tension and cylinder pressure loading, both of which act outwards on the ring and conform it to the cylinder bore. There is also the radial inward force as the result of ring-bore conjunctional pressure (i.e. contact force). Under transient conditions, the inward and outward forces do not equilibrate, resulting in the small inertial radial motion of the ring.
Technical Paper

An Assessment of a Sensor Network Using Bayesian Analysis Demonstrated on an Inlet Manifold

2019-04-02
2019-01-0121
Modern control strategies for internal combustion engines use increasingly complex networks of sensors and actuators to measure different physical parameters. Often indirect measurements and estimation of variables, based off sensor data, are used in the closed loop control of the engine and its subsystems. Thus, sensor fusion techniques and virtual instrumentation have become more significant to the control strategy. With the large volumes of data produced by the increasing number of sensors, the analysis of sensor networks has become more important. Understanding the value of the information they contain and how well it is extracted through uncertainty quantification will also become essential to the development of control architecture. This paper proposes a methodology to quantify how valuable a sensor is relative to the architecture. By modelling the sensor network as a Bayesian network, Bayesian analysis and control metrics were used to assess the value of the sensor.
Technical Paper

A Bifurcation Analysis of an Open Loop Internal Combustion Engine

2019-04-02
2019-01-0194
The process of engine mapping in the automotive industry identifies steady-state engine responses by running an engine at a given operating point (speed and load) until its output has settled. While the time simulating this process with a computational model for one set of parameters is relatively short, the cumulative time to map all possible combinations becomes computationally inefficient. This work presents an alternative method for mapping out the steady-state response of an engine in simulation by applying bifurcation theory. The bifurcation approach used in this work allows the engine’s steady-state response to be traced through the model’s state-parameter space under the simultaneous variation of one or more model parameters. To demonstrate this approach, a bifurcation analysis of a simplified nonlinear engine model is presented.
Technical Paper

Robust Methodology for Fast Crank Angle Based Temperature Measurement

2016-04-05
2016-01-1072
The paper presents a measurement methodology which combines a fine-wire thermocouple with input reconstruction in order to measure crank angle resolved temperature in an engine air-intake system. Thermocouples that are of practical use in engine experiments tend to have a large time constant which affects measurement accuracy during rapid temperature transients. Input reconstruction methods have previously been applied to thermocouples but have not been specifically used in combination with an ultra-thin uninsulated wire thermocouple to investigate cyclic intake temperature behavior. Accurate measurement results are of interest to improve the validity of many crank-angle resolved engine models. An unshielded thermocouple sensor has been developed which is rigid enough to withstand the aerodynamic forces of the intake air.
Technical Paper

The Position Control of a Gasoline Engine during Shutdown

2017-03-28
2017-01-1630
Since the first stop-start system introduced in 1983, more and more vehicles have been equipped with this kind of automatic engine control system. Recently, it was found that there is strong correlation between engine resting position and the subsequent engine start time. The utilization of the synchronization time working from a required engine stop position prior the engine start request was shown to reduce start times. Hence the position control of an engine during shutdown becomes more significant. A naturally aspirated engine was modelled using the GT-Suite modelling environment to facilitate the development of position controllers using Simulink ®. The use of respectively the throttle and a belt mounted motor generator to provide a control input was considered. Proportional-Integral-Differential (PID), sliding mode and deadbeat control strategies were each used in this study.
Technical Paper

Review of Selection Criteria for Sensor and Actuator Configurations Suitable for Internal Combustion Engines

2018-04-03
2018-01-0758
This literature review considers the problem of finding a suitable configuration of sensors and actuators for the control of an internal combustion engine. It takes a look at the methods, algorithms, processes, metrics, applications, research groups and patents relevant for this topic. Several formal metric have been proposed, but practical use remains limited. Maximal information criteria are theoretically optimal for selecting sensors, but hard to apply to a system as complex and nonlinear as an engine. Thus, we reviewed methods applied to neighboring fields including nonlinear systems and non-minimal phase systems. Furthermore, the closed loop nature of control means that information is not the only consideration, and speed, stability and robustness have to be considered. The optimal use of sensor information also requires the use of models, observers, state estimators or virtual sensors, and practical acceptance of these remains limited.
Technical Paper

Analysis of a Novel Method for Low-Temperature Ammonia Production Using DEF for Mobile Selective Catalytic Reduction Systems

2018-04-03
2018-01-0333
The worldwide introduction of new emission standards and new, more encompassing, legislating cycles have led to a need to increase both a selective catalytic reduction (SCR) system’s capacity and conversion efficiency. To this end, it is important for an SCR system to operate to the extremes of its temperature range which in many systems is currently limited by the temperature at which diesel exhaust fluid (DEF) can easily decompose without the formation of deposits. This paper analyses a new system for low-temperature ammonia provision to the SCR reaction. Ammonia Creation and Conversion Technology (ACCT) uses pressure controlled thermal decomposition of DEF followed by re-formation to form a fluid with greater volatility and the same ammonia density as DEF conforming to ISO 22241. A dosing strategy can then be employed where any combination of DEF or ACCT solution can be used to provide ammonia as a reductant over the whole activity temperature range of a catalyst.
Technical Paper

Cycle-to-Cycle Variation Analysis of Two-Colour PLIF Temperature Measurements Calibrated with Laser Induced Grating Spectroscopy in a Firing GDI Engine

2019-04-02
2019-01-0722
In-cylinder temperatures and their cyclic variations strongly influence many aspects of internal combustion engine operation, from chemical reaction rates determining the production of NOx and particulate matter to the tendency for auto-ignition leading to knock in spark ignition engines. Spatially resolved measurements of temperature can provide insights into such processes and enable validation of Computational Fluid Dynamics simulations used to model engine performance and guide engine design. This work uses a combination of Two-Colour Planar Laser Induced Fluorescence (TC-PLIF) and Laser Induced Grating Spectroscopy (LIGS) to measure the in-cylinder temperature distributions of a firing optically accessible spark ignition engine. TC-PLIF performs 2-D temperature measurements using fluorescence emission in two different wavelength bands but requires calibration under conditions of known temperature, pressure and composition.
Technical Paper

Towards In-Cylinder Flow Informed Engine Control Strategies Using Linear Stochastic Estimation

2019-04-02
2019-01-0717
Many modern I.C. engines rely on some form of active control of injection, timing and/or ignition timing to help combat tailpipe out emissions, increase the fuel economy and improve engine drivability. However, development of these strategies is often optimised to suit the average cycle at each condition; an assumption that can lead to sub-optimal performance, especially an increase in particulate (PN) emissions as I.C. engine operation, and in-particular its charge motion is subject to cycle-to-cycle variation (CCV). Literature shows that the locations of otherwise repeatable large-scale flow structures may vary by as much 25% of the bore dimension; this could have an impact on fuel break-up and distribution and therefore subsequent combustion performance and emissions.
Technical Paper

Real Time Energy Management of Electrically Turbocharged Engines Based on Model Learning

2019-04-02
2019-01-1056
Engine downsizing is a promising trend to decarbonise vehicles but it also poses a challenge on vehicle driveability. Electric turbochargers can solve the dilemma between engine downsizing and vehicle driveability. Using the electric turbocharger, the transient response at low engine speeds can be recovered by air boosting assistance. Meanwhile, the introduction of electric machine makes the engine control more complicated. One emerging issue is to harness the augmented engine air system in a systematical way. Therefore, the boosting requirement can be achieved fast without violating exhaust emission standards. Another raised issue is to design an real time energy management strategy. This is of critical to minimise the required battery capacity. Moreover, using the on-board battery in a high efficient way is essential to avoid over-frequent switching of the electric machine. This requests the electric machine to work as a generator to recharge the battery.
Technical Paper

Application of Multi-Objective Optimization Techniques for Improved Emissions and Fuel Economy over Transient Manoeuvres

2019-04-02
2019-01-1177
This paper presents a novel approach to augment existing engine calibrations to deliver improved engine performance during a transient, through the application of multi-objective optimization techniques to the calibration of the Variable Valve Timing (VVT) system of a 1.0 litre gasoline engine. Current mature calibration approaches for the VVT system are predominantly based on steady state techniques which fail to consider the engine dynamic behaviour in real world driving, which is heavily transient. In this study the total integrated fuel consumption and engine-out NOx emissions over a 2-minute segment of the transient Worldwide Light-duty Test Cycle are minimised in a constrained multi-objective optimisation framework to achieve an updated calibration for the VVT control. The cycle segment was identified as an area with high NOx emissions.
Technical Paper

Using Ion-current Sensing to Interpret Gasoline HCCI Combustion Processes

2006-04-03
2006-01-0024
Homogeneous charge compression ignition (HCCI), combustion has the potential to be highly efficient and to produce low NOx, carbon dioxide and particulate matter emissions, but experiences problems with cold start, running at idle and producing high power density. A solution to these is to operate the engine in a ‘hybrid mode’, where the engine operates in spark ignition mode at cold start, idle and high loads and HCCI mode elsewhere during the drive cycle, demanding a seamless transition between the two modes of combustion through spark assisted controlled auto ignition. Moreover; HCCI requires considerable control to maintain consistent start of combustion and heat release rate, which has thus far limited HCCI's practical application. In order to provide a suitable control method, a feedback signal is required.
Technical Paper

The Measurement of Liner - Piston Skirt Oil Film Thickness by an Ultrasonic Means

2006-04-03
2006-01-0648
The paper presents a novel method for the measurement of lubricant film thickness in the piston-liner contact. Direct measurement of the film in this conjunction has always posed a problem, particularly under fired conditions. The principle is based on capturing and analysing the reflection of an ultrasonic pulse at the oil film. The proportion of the wave amplitude reflected can be related to the thickness of the oil film. A single cylinder 4-stroke engine on a dyno test platform was used for evaluation of the method. A piezo-electric transducer was bonded to the outside of the cylinder liner and used to emit high frequency short duration ultrasonic pulses. These pulses were used to determine the oil film thickness as the piston skirt passed over the sensor location. Oil films in the range 2 to 21 μm were recorded varying with engine speeds. The results have been shown to be in agreement with detailed numerical predictions.
Technical Paper

The HOTFIRE Homogeneous GDI and Fully Variable Valve Train Project - An Initial Report

2006-04-03
2006-01-1260
There is a great deal of interest in new technologies to assist in reducing the CO2 output of passenger vehicles, as part of the drive to meet the limits agreed by the EU and the European Automobile Manufacturer's Association ACEA, itself a result of the Kyoto Protocol. For the internal combustion engine, the most promising of these include gasoline direct injection, downsizing and fully variable valve trains. While new types of spray-guided gasoline direct injection (GDI) combustion systems are finally set to yield the level of fuel consumption improvement which was originally promised for the so-called ‘first generation’ wall- and air-guided types of GDI, injectors for spray-guided combustion systems are not yet in production to help justify the added complication and cost of the NOx trap necessary with a stratified combustion concept.
Technical Paper

Analysis of SI Combustion Diagnostics Methods Using Ion-Current Sensing Techniques

2006-04-03
2006-01-1345
Closed-loop electronic control is a proven and efficient way to optimize spark ignition engine performance and to control pollutant emissions. In-cylinder pressure sensors provide accurate information on the quality of combustion. The conductivity of combustion flames can alternatively be used as a measure of combustion quality through ion-current measurements. In this paper, combustion diagnostics through ion-current sensing are studied. A single cylinder research engine was used to investigate the effects of misfire, ignition timing, air to fuel ratio, compression ratio, speed and load on the ion-current signal. The ion-current signal was obtained via one, or both, of two additional, remote in-cylinder ion sensors (rather than by via the firing spark plug, as is usually the case). The ion-current signals obtained from a single remote sensor, and then the two remote sensors are compared.
Technical Paper

Experimental Study of DI Diesel Engine Performance Using Three Different Biodiesel Fuels

2006-04-03
2006-01-0234
Methyl esters derived from vegetable oils by the process of transesterification (commonly referred as ‘biodiesel’), can be used as an alternative fuel in compression ignition engines. In this study, three different vegetable oils (rape, soy and waste oil) were used to produce biodiesel fuels that were then tested in a four cylinder direct injection engine, typically used in small diesel genset applications. Engine performance and emissions were recorded at five load conditions and at two different speeds. This paper presents the results obtained for measurements of NOx and smoke opacity at the different speed and load conditions for the three biodiesels, and their blends (5 and 50% v/v) with mineral diesel. A simple combustion analysis was also performed where ignition delay, position and magnitude of peak cylinder pressure and heat release rate were examined to asses how the variation of chemical structure and blend percentage affects engine performance.
Technical Paper

Comparison between Unthrottled, Single and Two-valve Induction Strategies Utilising Direct Gasoline Injection: Emissions, Heat-release and Fuel Consumption Analysis

2008-06-23
2008-01-1626
For a spark-ignition engine, the parasitic loss suffered as a result of conventional throttling has long been recognised as a major reason for poor part-load fuel efficiency. While lean, stratified charge, operation addresses this issue, exhaust gas aftertreatment is more challenging compared with homogeneous operation and three-way catalyst after-treatment. This paper adopts a different approach: homogeneous charge direct injection (DI) operation with variable valve actuations which reduce throttling losses. In particular, low-lift and early inlet valve closing (EIVC) strategies are investigated. Results from a thermodynamic single cylinder engine are presented that quantify the effect of two low-lift camshafts and one standard high-lift camshaft operating EIVC strategies at four engine running conditions; both, two- and single-inlet valve operation were investigated. Tests were conducted for both port and DI fuelling, under stoichiometric conditions.
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