bluuebunny/crossref_metadata_2025 huggingface dataset:
Implicit regulation for automotive variators
Authors: Beccari A , Cammalleri M
Published: October 2002

A well-known practice uses mechanical variators to realize the so-called continuously variable transmissions (CVTs) for automotive application. A remarkable problem for one of the most used CVTs is given by the hydraulic control of the axial thrust on the half-pulleys that is necessary for torque transmission. It involves a heavy decrease in transmission efficiency.

In the present paper, the possible production of the required axial thrust by a simple spring to eliminate hydraulic losses is analysed. It is shown that the power capacity of such a regulated variator is near to the maximum possible, and the belt torque loss is always considerably lower than the sum of the belt and pump losses of a standard controlled CVT. Moreover, it is not much greater than a slip limit controlled CVT for medium-low vehicle speeds, and slightly lower for higher speeds. Finally, the power capacity by the spring thrust is evaluated when the variator is used in split power transmissions, considering several configurations and steady ideal operation.
Reconstructing cylinder pressure from vibration signals based on radial basis function networks
Authors: Du H , Zhang L , Shi X
Published: October 2002

This paper presents an approach to reconstruct internal combustion engine cylinder pressure from the engine cylinder head vibration signals, using radial basis function (RBF) networks. The relationship between the cylinder pressure and the engine cylinder head vibration signals is analysed first. Then, an RBF network is applied to establish the non-parametric mapping model between the cylinder pressure time series and the engine cylinder head vibration signal frequency series. The structure of the RBF network model is presented. The fuzzy c-means clustering method and the gradient descent algorithm are used for selecting the centres and training the output layer weights of the RBF network respectively. Finally, the validation of this approach to cylinder pressure reconstruction from vibration signals is demonstrated on a two-cylinder, four-stroke direct injection diesel engine, with data from a wide range of speed and load settings. The prediction capabilities of the trained RBF network model are validated against measured data.
An optimum design methodology development using a statistical technique for vehicle occupant safety
Authors: Hong J. H. , Mun M. S. , Song S. H.
Published: October 2002

In this study, an optimization methodology was developed to obtain design parameters for a frontal occupant impact protection problem using a statistical approach. The central composite design was applied to occupant simulations. On the basis of the design, a total of 25 simulations were performed. The second-order multiple regression injury functions about the head injury criterion (HIC), 3 ms chest acceleration, chest deflection, and right and left femur loads were constructed with high coefficient of determination values and statistical significance ( r2 > 0.8 and p 0.001). Then, the response surface method (RSM) was applied to this multicriterion optimization problem, and optimum design parameters about the airbag vent characteristics, triggering time, mass flowrate and knee foam stress-strain relationship were obtained. After the optimized design, the 3 ms chest acceleration, right and left femur loads were reduced by 25.5, 7.1 and 19.9 per cent respectively. These results suggest that the proposed method is useful and effective for automotive safety design problems.
Active vibration control of a suspension system using an electromagnetic damper
Authors: Kim Y-B , Hwang W-G , Kee C-D , Yi H-B
Published: October 2002

This paper is concerned with the design and implementation of a magnetic damper system to reduce the vibration of a suspension system actively. A cylindrical-type electromagnetic actuator with a permanent magnet is analysed and an effective controller design is made. An accurate force analysis is carried out for the given system. An accurate transfer function for the total system is determined by experimental data using an error minimization method. For experiments, a simple suspension structure system is utilized, in which a magnetic damper composed of a permanent magnet and digital controller is attached. In order to drive the system, a bipolar power amplifier of the voltage control type is utilized. A stable and high speed control board is used to implement digital control logic for the given system. This paper shows that the magnetic damper system using a phase lead controller is excellent in reducing the vibration of a one-degree-of-freedom suspension system.
Experimental study of operating performance of a tube-and-fin radiator for vehicles
Authors: Chen J. A. , Wang D. F. , Zheng L. Z.
Published: October 2002

In this paper, an experimental study of the heat transfer characteristics of a tube-and-fin radiator for vehicles is carried out by using an experimental optimization design technique on a wind tunnel test rig of the radiator. The regression equations of heat dissipation rate, coolant pressure drop and air pressure drop are developed. The influences of the air velocity, inlet coolant temperature and volume flowrate of coolant on heat dissipation rate, coolant pressure drop and air pressure drop are discussed in detail by means of the numerical analyses. Also, the research results provide a basis for the theoretical analysis of heat performances and structural refinement of the tube-and-fin radiator.
Measurement of road gradients for the development of driving modes including road gradients
Authors: Park J. H. , Kong J. H. , Jo H. S. , Park Y. I. , Lee J. M.
Published: October 2002

In this study, new driving modes which include road gradients are proposed because the road gradient resistance has an influence on the fuel economy and the emissions of vehicles. However, the mode which is widely used to estimate the fuel economy and the emissions of vehicles was constructed with the assumption that all the roads were flat. To develop the new driving modes, algorithms to measure road gradients in real time are studied. A few published patented methods of measuring road gradients are experimented with, and the results according thereto are presented. The best method is then selected to make driving modes that are more similar to on-road driving conditions. On-road car tests are carried out to develop the new modes, and then comparisons between the worldwide driving modes and the new driving modes are made.
A computational and experimental study of the scavenging flow in the transfer duct of a motored two-stroke cycle engine
Authors: Creaven J. P. , Kenny R. G. , Fleck R , Cunningham G
Published: October 2002

This study was carried out to assess the ability of a computational fluid dynamics (CFD) code to predict the scavenging flow in the transfer duct of a two-stroke cycle engine. A two-stroke cycle engine was modified to allow laser Doppler velocimetry (LDV) measurements to be made in one transfer duct. It was operated under motoring conditions at 500r/min with a delivery ratio of 0.7. Predictions were obtained from a dynamic CFD simulation of the flow within the cylinder, transfer duct and a portion of the exhaust duct. Boundary conditions for the CFD model were obtained from experimentally measured pressure-time histories in the crankcase and exhaust. A comparison of measured and predicted transfer duct axial velocities at various locations within the duct showed that the CFD model could replicate the general trend of the flow but not the details. From the LDV measurements and CFD predictions, velocity oscillations were observed between the end of crankcase blowdown and transfer port closing. A one-dimensional general engine simulation package was used to investigate the gas dynamic activity in the transfer duct. It was found that the observed oscillations were due to pressure wave reflections in the transfer duct. The general trend of the axial velocity profile in the transfer duct was well replicated by the one-dimensional simulation as were the exhaust and crankcase pressures.
Technical Note: Construction of race circuit geometry from on-car measurements
Authors: Casanova1 D , Sharp R. S. , Symonds P
Published: October 2002

Forward speed and lateral acceleration data obtained from a Formula One car under semi-competitive conditions are employed to reconstruct the planar geometry of the circuit traversed. Methods devised depend on first smoothing the data by low pass filtering and cubic spline interp-olation and then using numerical integration on combined speed and acceleration signals. Two methods for the integration parts are designed and discussed. They involve different methods for error correction, which, uncorrected, lead to the circuit analysed not closing up without discontinuities at the start-finish line. Results from each of the two methods for the Barcelona and Suzuka Formula One circuits are given. Comparisons are made between the known geometry for each of these circuits and that reconstructed from the recorded data. Conclusions are drawn relating to method and accu-racy. Suggestions are made on how the currently exposed processing may be improved by further work.
Technical Note: Vehicle simulation program: A tool to evaluate hybrid power management strategies based on an innovative iteration algorithm
Authors: Van Mierlo J , Maggetto G
Published: October 2002

In the framework of a PhD research programme [1] a vehicle simulation program is developed. It is a modular user-friendly interactive programme that allows the simulation of the behaviour of electric (battery, hybrid and fuel cell) as well as internal combustion (petrol, diesel, CNG, etc.) vehicles. The goal of the simulation program is to study power flows in drivetrains and corresponding component losses as well as to compare different drivetrain topologies. This comparison can be realized at the level of consumption (fuel and electricity) and emissions (CO2, HC, NOx, CO, particles, etc.) as well as at the level of performance (acceleration, range, maximum slope). The main modelling aspects and research ‘trigger points’, including its innovative iteration algorithm, will be highlighted in this paper.
Simulation of non-stationary vehicle vibrations
Authors: Rouillard V , Sek M. A.
Published: October 2002

This paper introduces a new method for the analysis and simulation of non-stationary random vibrations. The method pays particular attention to the non-stationary nature of vibrations generated by transport vehicles. The limitations of current methods used for analysing and simulating non-stationary random vehicle vibrations are demonstrated. The paper shows how the Hilbert transform can be used to compute the vibration intensity (VI) and offers substantial data reduction advantages. It is shown how the statistical distribution of VI can be combined with the spectral characteristics of the vibration signal to enable more realistic simulations of non-stationary transport vibrations.
Technical Note: Viscous contribution to minimum static pressure in a rapidly rotating transfer passage
Authors: Papa F , Vaidyanathan K , Keith T. G. , DeWitt K. J. , Masiulaniec K. C.
Published: October 2002

This paper describes a one-dimensional model that predicts the minimum static pressure in a rotating transfer passage taking into account both the centrifugal and the viscous forces, the latter having been neglected in previous studies. The minimum pressure is important as it determines the engine lubricating capacity and whether aero-cavitation may occur in the passage. The flow is considered laminar and the fluid is incompressible and Newtonian with constant viscosity. The current model predicts a lower minimum pressure within the transfer passage due to the inclusion of the viscous forces in the model.
Optimum design of an A-pillar trim with rib structures for occupant head protection
Authors: Kim H. G. , Kang S
Published: October 2002

The National Highway Traffic Safety Administration (NHTSA) has been conducting biomechanical studies to reduce head injuries sustained during automotive collision. Furthermore, NHTSA added a new regulation to the Federal motor vehicle safety standard FMVSS201, limiting the equivalent head injury criterion (HIC) value to under 1000. In the present study, a methodology is developed for the optimum design of the A-pillar trim with rib structures, which can maximize the energy dissipation during head impact. The design variables for the rib structures are the transverse spacing, the longitudinal spacing and the thickness. The required set of design variables is decided upon on the basis of the design of experiments. A series of simulations for head impact to A-pillar trim are carried out by using the explicit finite element (FE) code LS-DYNA3D, and the HIC(d) values are computed using results from simulations utilizing design variables determined by a combination of the central composite design and the full factorial design. A proper regression function with an R 2 value above 0.9 was constructed using the response surface method, and it was used as an objective function for optimization. An HIC(d) value under 850 for 15 mile/h head-trim impact was obtained using the rib structures suggested by the present design methodology.
Case Study: Infinitely variable transmissions with automatic regulation
Authors: Mantriota G
Published: October 2002

An infinitely variable transmission (IVT) is a continuously variable transmission with an infinite ratio range, which means that the transmission ratio may be zero. IVTs are generally made up of three elements: a continuously variable transmission (CVT), a planetary gear train and a fixed ratio mechanism. Automatically regulated CVTs offer the advantage of automatically changing the transmission ratio without requiring sophisticated control systems. In this work the possibility of realizing an automatically regulated IVT is appraised, i.e. with automatic regulation of the transmission ratio, in relation to operational conditions. The use of the automatically regulated V-belt CVT, endowed with simple devices of axial force, is hypothesized. For the different types of devices the characteristic curves of operation, the power flows and the efficiency of the automatically regulated IVT are determined.
Solenoid-operated diesel injectors for low-viscosity liquid and gaseous fuels
Authors: Hong H , Torab B
Published: October 2002

Alternative fuels such as liquid dimethyl ether have low viscosity that result in fuel leakage in diesel components, while natural gas and hydrogen are too compressible for diesel pressure operated injection. A new solenoid-operated injector design for diesel alternative fuels is described. Less force is required to open the injector because of the pressure-balanced design by having the pressure across the needle guide the same. A pulling rod is attached between the electrical solenoid core and needle guide. Activating the solenoid produces the electromagnetic force to pull open the injector needle. Circulation of the fuel through the common rail housing the solenoids is used to prevent the coils from excessive heat that tends to reduce the solenoid force. On injector closing, the elasticity of the pulling rod provides relative motion damping so that the core's inertia force is reduced as it is transferred to the needle. This results in lower impact forces between the needle and its seat and lessens their wear. Also, the magnitude of the needle seat bounce is attenuated and results in less post-injection and emission pollutants. The study of needle-to-seat impact forces has been modelled for computer simulation and has been verified with experiments.
Understanding of controlled autoignition combustion in a four-stroke gasoline engine
Authors: Zhao H , Peng Z , Ladommatos N
Published: October 2002

Controlled autoignition (CAI) combustion has recently emerged as a viable alternative combustion process to the conventional spark ignition or compression ignition process for internal combustion engines, owing to its potential for high efficiency and extremely low NOx and particulate emissions. Since CAI combustion is a process dominated by chemical kinetics of the fuel-air mixture, an engine simulation model with detailed chemical kinetics has been developed and applied to a four-stroke gasoline engine fuelled with isooctane. After calibration and validation, the engine simulation model was used to study the effects of the intake temperature, exhaust gas recirculation (EGR), the air-fuel ratio, the compression ratio and the engine speed on CAI combustion in a four-stroke gasoline engine. The characteristics of CAI combustion investigated include the autoignition timing, the partial burning and knocking combustion and NO emission. Results show that CAI combustion could be achieved within a limited speed and load range. The lower end of the CAI combustion range was affected by partial burning, and the higher end of its operation was limited by knocking combustion. Among the engine parameters investigated, the intake charge temperature and EGR had the greatest effect on the CAI combustion process. The effect of EGR was further analysed in terms of its thermal (increase in heat capacity), dilution, chemical and charge heating effects by means of a series of simulation studies. It was found that the charge heating effect caused advanced ignition timing, faster heat release rate and moderate reduction in the CAI combustion duration. The thermal effect (increased heat capacity) retarded ignition, extended combustion duration and slowed down heat release rate. The dilution effect also resulted in longer combustion duration and slower burning but it did not affect the ignition timing. The chemical effect was found to accelerate the combustion process when the percentage of EGR was large.
Condensed joint matrix method for the joint structure of a vehicle body
Authors: Suh M-W , Suhr J , Yang W-H
Published: October 2002

It is often necessary that the joint characteristics should be determined in the early stage of a vehicle body design. Until recently, much research has been carried out to identify the joint characteristics in a vehicle body. In this study, the joint characteristics of a vehicle structure were expressed as the condensed matrix forms from the full joint stiffness matrix. The condensed joint stiffness matrix was applied to typical T-type and corner-type joints, and practical applications, such as the real centre pillar and vehicle body structure, are examined by using the proposed method. In addition, it was applied to the real centre pillar model and the full vehicle body in order to validate the practical application.
A method to identify vibration characteristics of modified structures for flexible vehicle dynamics
Authors: Yi T. Y. , Nikravesh P. E.
Published: October 2002

This paper presents a new method for predicting vibration characteristics of a structure that is considered to undergo a design change. It is assumed that for the original structure the vibration data are available either as a complete or as an incomplete set. On the basis of the available vibration data and the known data on the design change, this paper discusses methodologies for determining the vibration characteristics of the modified structure. By considering practical situations, the emphasis of this paper is on structures for which a finite element model, and hence a stiffness matrix, is not available. If a finite element model of the structure is already available, then predicting the modal characteristics of the modified or redesigned structure may be a trivial task. However, if a finite element model of the structure is not available, then a more economical procedure would be to predict the vibration characteristics of the modified structure from experimcopy IMentally obtained vibration data. Here the idea is to use the available vibration data and to combine them with the structural data of the proposed design change, in order to predict the vibration characteristics of the modified structure. When the vibration data for a structure are obtained experimcopy IMentally, probably only a limcopy IMited number of mode shapes and their corresponding natural frequencies can be computed (an incomplete set of modal data). This paper presents the necessary formulations for both complete and incomplete mode sets. Although the main portion of the paper concentrates on identifying the structural stiffness matrix, a methodology is also presented for mass matrix identification. For validating the developed formulations, two examples with numerical results are presented.
Stiffness properties of small-sized pneumatic tyres
Authors: Ramji K. , Goel V. K. , Saran V. H.
Published: October 2002

The vertical, longitudinal and lateral dynamic behaviour of road vehicles is largely influenced by the dynamic characteristics of tyres. The tyre characteristics have been modelled by researchers as functions of the tyre elastic properties which are characterized by tyre vertical, lateral, longitudinal and torsional stiffnesses. Design details of an experimental rig for measurement of tyre static stiffnesses are presented, and experimental data on these stiffness values in the form of a power law as functions of tyre size, ply rating, normal load and inflation pressure are reported. Using tyre models, the tyre force and moment characteristics necessary for vertical dynamic simulation can be predicted.
Three-point seatbelt maternal comfort and fetal safety
Authors: Thackray L A , Blackketter D M
Published: October 2002

This paper presents the results of a study that evaluated the comfort and safety of three-point seatbelt use by pregnant women. Comfort was assessed by developing and administering a survey. Two hundred responses revealed high levels of discomfort due to the lap belt riding up onto the abdomen (64.5 per cent), the edges of the lap belt rubbing on the abdomen and thighs (61.5 per cent), compression of breasts by the torso belt (48 per cent) and the lap belt being too tight or too short (50 per cent).

Evaluating seatbelt safety for the fetus was accomplished by reviewing case studies involving pregnant crash victims as well as baboon crash test results. Additionally, computer simulations, modelling a 35 mile/h collision with a pregnant woman in a three-point restraint, were developed. The simulations were used to predict fetal movement and acceleration behaviour relative to the mother. Fetal acceleration was found to reach values nearly 3 times greater than maternal acceleration, offering justification as to why a fetus might die as a result of abruptio placentae or skull injury.
A fatigue design method for spot-welded lap joints
Authors: Bae Dongho , Sohn Ilseon , Jung Wonseok , Song Sung-Jin
Published: October 2002

Recently, a new issue in the design of spot-welded structures has been economical prediction of a fatigue design criterion without additional fatigue tests. In general, the most typical and traditional method is the use of a Δ P- Nf curve. However, since the fatigue data on the curve vary according to welding conditions, materials, geometry and fatigue loading conditions, it is necessary to perform an additional fatigue test in order to determine a new fatigue design criterion for a spot-welded lap joint of different dimensions and geometry. This is, of course, a very time consuming and costly task. Thus, in this paper, an economical and advanced design method is proposed, the reliability and performance of which have been verified with the theory of the Weibull probability distribution. As a mechanical parameter to predict the fatigue design criterion, a maximum stress equation has been defined using artificial neural networks. By using the maximum stress equation and the fatigue data previously obtained from fatigue tests, a reasonable fatigue design criterion for a spot-welded lap joint could be predicted without any additional fatigue tests. The results predicted by this method showed very good agreement with actual fatigue data
A comparison of combustion characteristics of waste cooking oil with diesel as fuel in a direct injection diesel engine
Authors: Yu C W , Bari S , Ameen A
Published: October 2002

The use of waste cooking oil (WCO) as an alternative to diesel in engines has advantages from both economic and environmental standpoints. Typical of vegetable oils, WCO has a higher viscosity, leading to a general perception that its use is likely to have an adverse effect on the fuel injection system and consequent combustion process. In the present investigation, tests were carried out to determine engine performance and combustion analysis as well as emissions for both WCO and diesel. It was observed that because of the shorter ignition delay the premixed combustion phase of WCO was less intense than that of diesel. However, because of the corresponding smaller combustion volume, the peak pressures were on average 1.5 bar higher and occurred 1.1°-3.8° earlier than for diesel. This early peaking characteristic requires careful attention to ensure that, while running with WCO, the peak pressure takes place marginally after top dead centre for efficient operation. In terms of emissions of CO, NO and SO2, the level was higher for WCO compared with diesel.
Effects of body leakage on ventilation and wind noise around a sunroof
Authors: Lee Y L
Published: October 2002

Some passenger cars with sunroofs open at tilted positions experience reverse flows into cabin rooms and wind noises much louder than in other cars. In this study, flows around an open tilted sunroof are numerically studied with varying body leakage. The effects of body leakage on ventilation and wind noise of a sunroof are examined, in particular. Furthermore, flow visualization, pressure and wind noise measured from the wind tunnel and road tests are presented. The results show that too small a body leakage results in poor ventilation performance and generates high wind noises around a sunroof. It is therefore very important to secure an adequate body leakage from the early design stage to achieve better performance of a sunroof as well as passengers' thermal comfort.
Potential of use of ion implantation as a means of catalyst manufacturing
Authors: Zlobin V N , Bannikov M G , Vasilev I P , Cherkasov J A , Gawrilenko P N
Published: October 2002

The objective of this paper is to demonstrate the applicability of an ion implantation technique for catalyst manufacturing. The increasing production of vehicle catalysts has resulted in a growing consumption of the noble metals. Traditional methods of coating, such as impregnation, are thought to reduce the porosity and specific surface area of the catalysts. When ion implantation is used, the ions of the catalytic material are implanted into the substrate surface without affecting these properties. Several catalysts on different substrates were prepared by ion implantation and tested. The platinum-implanted catalyst showed a carbon monoxide (CO) conversion efficiency equal to that of the impregnated catalyst but with a 15 times lower platinum content. The CO conversion efficiency of the base metal based catalyst is doubled by platinum implantation. Details of the ion implantation parameters and test results are provided.
Modelling of NO emissions from homogeneous and stratified charge spark ignition engines
Authors: Raine R R , Wyszynski L , Stone R
Published: October 2002

The basis for modelling NO formation in spark ignition (SI) engines by the so-called thermal mechanism is reviewed, along with a comparison of the coefficients that have been recommended for use in the rate equations over the last 25 years. The importance of considering heat transfer, and a multizone representation of the burned gas, is demonstrated by reference to modelling NO in a homogeneous charge SI engine. The model has then been extended to a stratified charge SI engine, in order to investigate the influence of overall equivalence ratio and degree of stratification on the NO emissions and the engine brake specific fuel consumption. For fixed throttle operation, it is concluded that the best trade-off is with an overall weak mixture that is close to homogeneous. For maximum power output using a slightly rich stoichiometric mixture, the mixture should also be close to homogeneous. However, if the engine is constrained to operate with an overall stoichiometric mixture, then the trade-off between NO emissions and brake specific fuel consumption is with a stratified mixture that is rich at the spark plug.
A combined experimental and computational approach to improve catalyst flow uniformity and light-off behaviour
Authors: Kim H-S , Min K , Myung C-L , Park S
Published: October 2002

This study is concerned with the systematic approach to improve catalyst flow uniformity and light-off behaviour through the basic understanding of exhaust flow characteristics. An experimental and computational approach to the unsteady compressible flow for exhaust manifold and close-coupled catalyst (CCC) system attached to a four-cylinder double overhead camshaft gasoline engine was performed to investigate the flow distribution of exhaust gases and finally to increase the conversion efficiency of catalyst. An experimental study was conducted to measure the velocity distributions inside the exhaust manifold and CCC under practical engine conditions by using laser Doppler velocimetry. In this study, through experiment and calculation, the effects of the geometric configuration of exhaust manifold on flow structure and its maldistribution in the monolith were mainly investigated to understand the exhaust flow patterns in terms of flow uniformity and to obtain the better light-off for further emission reduction. On the basis of the design guidance resulting from this fundamental study, an improved exhaust manifold (type II) was designed and manufactured. The effects of improved exhaust flow characteristics on vehicle emission were demonstrated through the vehicle emission tests.
Modelling of turbocharged diesel engines in transient operation. Part 1: Insight into the relevant physical phenomena
Authors: Benajes J , Luján J M , Bermúdez V , Serrano J R
Published: October 2002

A new calculation model, able to predict the engine performance during an engine transient, has been developed, based on an existing wave action code. Previously to the model development, the turbocharged diesel engine's transient phenomena (turbocharger lag, thermal transient and energy transport delay) were deeply analysed on the basis of experimental information. The study has been focused on the load transient, i.e. torque increase from idle, at constant engine speed of a high speed direct injection (DI) turbocharged engine. Experimental load transient tests have been performed, with the aim of obtaining a combustion database during engine transient operation, to input into a combustion simulation submodel. The applied methodology allows the characterization of the transient combustion process in any DI turbocharged engine.
A multistage combustion model and soot formation model for direct-injection diesel engines
Authors: Micklow G J , Gong W
Published: October 2002

A multistage combustion model for diesel engines is presented in this paper. Three combustion stages, ignition of diesel, premixed combustion and diffusion combustion, are considered in the combustion process in a typical medium speed direct injection diesel engine. The transition from the ignition delay to the premixed combustion stage occurs when the highest temperature in the cylinder is beyond a critical value, and the transition from the premixed combustion model to the diffusion combustion model occurs when a calculated fraction of the premixed fuel is burned, which is determined from an empirical correlation based on the engine design and running conditions. Significant improvements in the predictions for in-cylinder pressure and heat release rate were achieved compared with previous models. A soot model based on the Hiroyasu soot formation mechanism and the Nagle and Strickland-Constable soot oxidation mechanism was implemented in a standard KIVA3V code. The effect of the OH radical in soot oxidation was also incorporated into the soot model. Computations show that OH plays an important role during the late combustion stage. Predicted soot and NOx were compared with measured values and a good agreement was achieved.
Implementation and vehicle tests of a vehicle stop-and-go cruise control system
Authors: Yi K , Ryu N , Yoon H J , Huh K , Cho D , Moon I
Published: October 2002

Implementation and vehicle tests of a vehicle longitudinal control algorithm for stop-and-go cruise control have been performed. The vehicle longitudinal control scheme consists of a set-speed control algorithm, a speed control algorithm, and a distance control algorithm. A desired acceleration for the vehicle for the control of vehicle-to-vehicle relative speed and clearance has been designed using linear quadratic optimal control theory. Performance of the control algorithm has been investigated via vehicle tests. Vehicle tests have been conducted using two test vehicles. A 2000 cm3passenger car equipped with a radar distance sensor, throttle/brake actuators and a controller has been used as a subject vehicle in the vehicle tests. A millimetre wave radar sensor has been used for distance measurement. A step motor and an electronic vacuum booster have been used for throttle/brake actuators. It has been shown that the implemented vehicle longitudinal control system can provide satisfactory performance in vehicle set-speed control and vehicle clearance control at lower speeds.
Performance of integrated engine-CVT control considering powertrain loss and CVT response lag
Authors: Kim T , Kim H
Published: October 2002

In this paper, an integrated engine-continuously variable transmission (CVT) control algorithm is suggested by considering the powertrain loss and the inertia torque due to the CVT ratio change. In addition, compensation algorithms to reduce the effect of the CVT ratio response lag on the drive torque are presented. Experimental results show that the optimal engine speed compensation algorithm gives better engine operation around the optimal operation line compared with the optimal torque compensation while showing nearly the same acceleration response. The performance of the proposed integrated engine-CVT control algorithms is compared with that of conventional CVT control, and it is found that better engine operation on the optimal operation line can be achieved by using integrated control during acceleration.
Simulation of continuously regenerating diesel particulate filters in transient driving cycles
Authors: Kandylas I P , Koltsakis G C
Published: October 2002

Forced by strict emission standards, interest in the reduction of particulate emissions becomes increasingly higher. Although the technology of diesel particulate filters (DPFs) has advanced impressively, especially during recent years, considerable technological challenges remain unsolved. The technology of NO2-assisted continuously regenerating diesel filters in conjunction with the upcoming availability of low sulphur diesel fuel represents a promising solution, especially for heavy duty engines. In the present paper, a transient modelling approach for the combined catalyst and DPF system is presented. This combined model is used to predict the regeneration performance of NO2-assisted regeneration systems in the transient conditions of a legislated European driving cycle. Although the model is based on global and approximate reaction schemes, the results illustrate the applicability of simulation tools in the process of optimizing certain important design parameters of the system, such as catalyst and particulate filter sizing and positioning, and catalyst activity requirements. It is expected that such engineering models will be valuable tools in the selection and design of such kind of systems, minimizing the testing effort and the associated costs.
Computer aided assessment and optimization of catalyst fast light-off techniques
Authors: Konstantinidis P. A. , Koltsakis G. C. , Stamatelos A. M.
Published: October 2002

Strict future legislation standards are forcing the car industry to employ new techniques for reducing exhaust gas emissions. Most of these techniques focus on accelerating the appearance of catalyst light-off and are thus called fast light-off techniques (FLTs). Optimized exhaust systems comprising FLTs will be able to meet the forthcoming legislation standards for the United States [low emissions vehicle (LEV) and ultra-low emissions vehicle (ULEV)] and the European Union (Stage III). The most promising active and passive FLT systems are briefly reviewed. Computer aided optimization of such systems can be realized with the help of specific computational tools, which are briefly presented in this paper, and according to a concept optimization methodology, which is also discussed. The results indicate an increased sensitivity of FLT systems’ performance over the selected values of certain design and operating parameters that were featured in the examples presented. Moreover, by comparing the computational results with knowledge gained from experiments and testing, the paper indicates that, given the suitable computational tools, the optimization procedure can take place in a most cost-effective manner by substituting many experiments with computer test case runs.
Experimental and theoretical study of particulate re-entrainment from the combustion chamber walls of a diesel engine
Authors: Abu-Qudais M , Kittelson D. B.
Published: October 2002

The purpose of this research was to investigate the influence of the in-cylinder surfaces on the net emission of the particulate matter in the exhaust of a single cylinder, diesel engine. In order to obtain this information, time-resolved sampling was done to characterize the particulate matter emitted in the engine exhaust. A rotating probe sampled the free exhaust plume once each engine cycle. The rotation of the probe was synchronized with the engine cycle in such a way that the samples could be taken at any predetermined crank angle degree window. The sampling probe was designed for isokinetic sampling in order to obtain reliable results. To characterize the exhaust particulate in real time, a filter for mass concentration measurements was used. The results showed about 45 per cent higher mass concentrations as well as particles of larger diameter emitted during blowdown than late in the displacement phase of the exhaust stroke. This suggests that high in-cylinder shear rates and velocities which are associated with the blowdown process, cause the deposited soot to be re-entrained from the surfaces of the combustion chamber, where re-entrainment is favoured by conditions of high surface shear.

A mathematical model to predict the amount of soot re-entrained from the cylinder walls is presented. This model is based on information presented in the literature along with the results of the time-resolved measurements of mass concentration. This model supported the hypothesis of soot deposition during the combustion process, with subsequent re-entrainment during the blowdown process of the exhaust stroke.
Can increasing expenditure on research and development really be justified?
Authors: Bryson R. A.
Published: October 2002

Economists since Adam Smith have recognized the contribution of innovation to profitability and growth. The relationship between corporate research and development and subsequent sales growth, both across and within industries, has been examined by many authors. Results have been varied showing at best no more than the suggestion of a causal relationship between research and development input and growth.

These results are reviewed together with the various theories which have been developed in an attempt to explain the connection between technical innovation and growth. Starting with an examination of various national economies, the rate of commercial research and development expenditure has been compared to the rate of national growth. A number of industries in the United Kingdom, Germany, Japan and the United States of America were also examined, taking the automotive industry as a particular case. In addition to using published data a survey of smaller vehicle manufacturers in the United Kingdom was conducted. Although positive correlation was found at an international and industry level, no association between research and development expenditure and sales growth was found at a company or project level in the United Kingdom.
Analysis of the gas turbine rotary regenerator
Authors: Organ A. J.
Published: October 2002

Recent solution of the ‘Hausen’ regenerator and conjugate heat transfer problems invites a fresh look at the Ritz rotary regenerator. The approach deals readily with the reflux phase (‘hold-up’, flushing or ‘residence time’) and with the effects of friction (re-heating and pressure drop). There is no necessity to assume constant Stanton number, Nst, and friction factor, Cf. With accurate temperature and flow solutions available, recovery ratios in terms of operating parameters are a fait accompli. Optimization for specified duty becomes possible.
Measurement of air flowrate by using an integration type ultrasonic flow meter applicable for spark ignition engine control
Authors: Park K , Kim J , Kauh S. K. , Ro S. T. , Lee J
Published: October 2002

An integration type air flow meter (IFM), composed of an ultrasonic sensor with an integration circuit, is tested for the air flowrate measurement in a pulsating flow condition. An accurate air flowrate measurement is essential to control the fuel injection rate of a fuel injection spark ignition (SI) engine. The difficulty comes from the pulsating and reverse flow characteristics of the induction pipe. The IFM integrates the instantaneous flowrate signal during the quarter cycle corresponding to an intake period of a four-stroke four-cylinder engine in order to identify and account for the flow direction. The IFM has significantly improved the accuracy of flowrate measurement compared with a hot wire type flow meter in certain conditions where a flow reversal exists. The sampling method is also easier when using the IFM compared with other techniques.
Optimizing local charge stratification in a lean-burn spark ignition engine
Authors: Arcoumanis C , Hull D. R. , Whitelaw J. H.
Published: October 2002

Gas pressure and local gas velocities have been measured in a single-cylinder spark ignition engine operating at low load and 1000 r/min and the results have characterized the extent to which combustion was enhanced by the injection of a small quantity of a mixture of propane vapour and air towards the spark plug in an otherwise quiescent chamber filled with a homogeneous lean propane/air charge. The effects of the locally generated mean flow/turbulence and equivalence ratio on combustion were examined separately by first injecting a mixture of equivalence ratio identical to that of the homogeneous charge and then a slightly rich mixture into homogeneous charges of lower equivalence ratios.

The results show the advantageous effect of jet-induced local turbulence for overall air—fuel ratios between 17 and 24 with a maximum gain in peak pressure of 55 per cent at an air—fuel ratio of 20. The local injection of a rich mixture, in addition to increasing the gain in peak pressure from 30 to 50 per cent at an air—fuel ratio of 24, has extended the lean limit of the engine to 29. The timing of ignition relative to the end of injection, which varied as a function of the injection pressure, was found to have a strong effect on the peak combustion pressure so that, for example, a reduction of 8°(CA) in the time between the spark and the end of injection resulted in a 25 per cent reduction in combustion pressure at an air—fuel ratio of 22. The average flame speed was increased by local injection at all equivalence ratios; for example, a value of 7 m/s was obtained with local injection at an equivalence ratio of 0.7 which is equivalent to the flame speed measured with a homogeneous charge at the much higher equivalence ratio of 0.9.
Simultaneous reduction of particulate matter and NOx in a diesel engine by compressed gas injection: macroscopic study at residual load
Authors: Mkilaha I. S. N. , Inoue M , Kawai D , Naruse I , Ohtake K
Published: October 2002

A modified pre-chamber of an indirect injection (IDI) diesel engine was used to elucidate the influence on emissions of compressed air injection into the pre-chamber during combustion. The test parameters were air injection timing and arrangements of gas injection. This paper presents the experimental results for two types of injection arrangements; I- and Y-type. The I-type is arranged such that the gas injection jet and fuel injection nozzle are in opposite directions, while the Y-type is such that it forms a ‘Y’ shape with the nozzle and the passageway. Results obtained reveal that the Y-type arrangement is superior in combustion characteristics and emissions reduction to the I-type. A remarkable reduction in both particulate matter (PM) and NO x is realized at air injection timings during 35° and 65° after top dead centre (ATDC). The reduction mechanism can be explained as due to the induced turbulence which improves mixing and heat transfer. The effect of the modifications on the performance of the engine was evaluated based on the fuel economy and efficiency. This evaluation has shown that the test cylinder approximates closely to the normal cylinder of the original engine.
An investigation of the relationship between used engine oil properties and simulated intake valve deposits
Authors: Isa F M , Haji-Sulaiman M Z
Published: October 2002

The degradation of engine oil and its influence on the formation of intake valve deposits is being discussed in this paper. Degraded samples of oil were prepared using a stationary engine testbed while deposition studies were performed using a bench top simulator. The degree of degradation, as indicated by the amount of polymeric, oxidized and oxidative products, increases as the engine oil is used over a period of time. The rate of degradation, however, varies depending on the quality of base oil and the type of additives used. It was observed that the degraded oil played an important role in the formation of inlet valve deposits.
Dynamic performance simulation of a continuously variable transmission motorcycle for fuzzy autopilot design
Authors: Hong C W , Chen C C
Published: October 2002

This paper describes the modelling technique of a continuously variable transmission (CVT) motorcycle for control strategy design of an autopilot on a driving cycle test bench. The simulation is carried out on a code which is the combination of an engine cycle simulation synthesis, a dynamic CVT driveline algorithm, a chassis dynamometer model and a fuzzy autopilot controller. The autopilot, which is a robot driver, includes a throttle actuator and a brake handle controller. Fundamental fuzzy theories were employed to simulate the control strategy of an experienced driver, also to form a feedback control loop for the simulation. The whole simulation package is capable of predicting the motorcycle performance under dynamic road conditions, such as ECE R40 and USA FTP75 driving patterns. Simulation results of a baseline motorcycle, equipped with a 125 cm3 four-stroke engine plus a rubber belt CVT system, are demonstrated in this paper. Parametric studies are used to design the control strategy of the autopilot as well as to improve the design of the powertrain system of the motorcycle.