bluuebunny/crossref_metadata_2025 huggingface dataset:
Feedback error learning neural networks for spark advance control using cylinder pressure
Authors: Park S. , Yoon P. , Sunwoo M.
Published: October 2002

This paper presents a spark advance control strategy based on the location of peak pressure (LPP) in spark ignition engines using artificial neural networks. The well-known problems of the LPP-based spark advance control method are that many samples of data are required and there is a problem detecting the combustion phasing owing to hook-back during lean burn operation. In order to solve these problems, a feedforward multilayer perceptron network (MLPN) is introduced in this study. The LPP and hook-back are estimated using the MLPN, which needs only five samples of output voltage from the cylinder pressure sensor. The estimated LPP can be regarded as an index for combustion phasing and can also be used as a minimum spark advance for best torque (MBT) control parameter. The performance of the spark advance controller is improved by adding a feedforward controller which reflects the abrupt changes of the engine operating conditions such as engine speed and manifold absolute pressure. The feedforward controller consists of the radial basis function network, and the feedback error learning method is used for the training of the network. In addition, the proposed control algorithm does not need sensor calibration and pegging (bias calculation) procedures because the MLPN estimates the LPP from the raw sensor output voltage. The feasibility of this methodology to control spark advances is closely examined through steady and transient engine operations. The experimental results have revealed that the LPP shows favourable agreement with the optimal value even during the transient operation of the engine.
Additional adjustment of the driver seat in accordance with the latest anthropometric measurements of drivers in Belgrade
Authors: Klarin M. M. , Cvijanovic J. M. , Brkić V. K. Spasojević
Published: October 2002

This paper presents a sequel to research by two of the present authors published in 1998. In conditions of increasingly tough competition in the market, there is an increasing need to adjust automobiles to anthropomeasures. For the Yugoslav population the construction dimension of automobiles from floor to roof should be at least 1250 mm. Additional adjustment to meet the latest anthropomeasures of drivers should make it possible for the seat to slide backwards by up to 300 mm and to be linearly lowered by 131 mm (with an angle of 23.6° for the seat's complete shifting without backrest or the seat's seating part inclination change).
Electromyographic comparison of two lumbar support mechanisms intended for automotive seating applications
Authors: Kolich M , Taboun S. M. , Mohamed A. I.
Published: October 2002

The purpose of this study was to compare and contrast the effect of two lumbar support mechanisms on low back muscle activity. These mechanisms were designed to provide either microadjustment or massage. In the control condition, the lumbar support mechanism was set to the full-off position (0 mm of mechanism prominence). In this position, the foam contour supplied only a minimal amount of support. This condition, which is representative of traditional lumbar support design, was used to obtain an indication of the typical amount of low back muscle activity expected from automotive sitting. The data were collected using surface electrodes located at the L3 and L5 levels. Both lumbar support mechanisms provided a small reduction in low back muscle activity during a 1 h session. This can be contrasted with the control condition, which resulted in a small increase. In this respect, the mechanisms were considered an improvement on traditional lumbar support designs.
Technical Note: External torque application on antilock brake systems
Authors: Eren H , Göktan A. G.
Published: October 2002

The possibility of shortening the braking distance by the application of an additional driving torque linked to a control mechanism working with an ABS system is investigated in this work. In the ABS control cycle, the reacceleration of the locking wheels is provided only by decreasing the braking pressure. An external tractive torque can be used to shorten the time for acceleration during the phase of lowering of the braking pressure. The engine of the vehicle or an additional electric motor could be used as a source of external tractive force. The possibility of decreasing the braking distance by such a system is investigated by using a mathematical model. The effect of the additional accelerating torque is analysed with a simulation model and it is concluded that an increase of up to 10 per cent in braking distance may be obtained.
Theoretical and experimental study of a power split continuously variable transmission system Part 2
Authors: Mantriota G
Published: October 2002

In this work, theoretical and experimental results related to the power flow and efficiency of a power split continuously variable transmission (PS-CVT) system are reported. By means of two separate phases of operation, an original solution is studied that allows an increase in the transmission efficiency through the generation of a flow without recirculation of power. The experimental results related to the second phase of operation of the PS-CVT are reported. Such results are compared with those found through a theoretical model of the transmission. The advantages in terms of efficiency in comparison with a traditional CVT system are shown. A possible operational scheme for the PS-CVT is finally reported through which it is possible to increase the ratio range by means of a cyclical repetition of the operational phases.
The development of a two-dimensional transient catalyst model for direct injection two-stroke applications
Authors: McCullough G , Douglas R , Cunningham G , Foley L
Published: October 2002

This paper describes the development of a two-dimensional transient catalyst model. Although designed primarily for two-stroke direct injection engines, the model is also applicable to four-stroke lean burn and diesel applications. The first section describes the geometries, properties and chemical processes simulated by the model and discusses the limitations and assumptions applied. A review of the modelling techniques adopted by other researchers is also included. The mathematical relationships which are used to represent the system are then described, together with the finite volume method used in the computer program. The need for a two-dimensional approach is explained and the methods used to model effects such as flow and temperature distribution are presented. The problems associated with developing surface reaction rates are discussed in detail and compared with published research. Validation and calibration of the model are achieved by comparing predictions with measurements from a flow reactor. While an extensive validation process, involving detailed measurements of gas composition and thermal gradients, has been completed, the analysis is too detailed for publication here and is the subject of a separate technical paper
The validation of a two-dimensional transient catalyst model for direct injection two-stroke applications
Authors: McCullough G , Douglas R , Cunningham G , Foley L
Published: October 2002

This paper describes the detailed validation of a computer model designed to simulate the transient light-off in a two-stroke oxidation catalyst. A plug flow reactor is employed to provide measurements of temperature and gas concentration at various radial and axial locations inside the catalyst. These measurements are recorded at discrete intervals during a transient light-off in which the inlet temperature is increased from ambient to 300°C at rates of up to 6°C/s. The catalyst formulation used in the flow reactor and its associated test procedures are then simulated by the computer and a comparison made between experimental readings and model predictions. The design of the computer model to which this validation exercise relates is described in detail in a separate technical paper.

The first section of the paper investigates the warm-up characteristics of the substrate and examines the validity of the heat transfer predictions between the wall and the gas in the absence of chemical reactions. The predictions from a typical single-component CO transient light-off test are discussed in the second section and are compared with experimental data. In particular the effect of the temperature ramp on the light-off curve and reaction zone development is examined. An analysis of the C3H6 conversion is given in the third section while the final section examines the accuracy of the light-off curves which are produced when both CO and C3H6 are present in the feed gas.

The analysis shows that the heat and mass transfer calculations provided reliable predictions of the warm-up behaviour and post-light-off gas concentration profiles. The self-inhibition and cross-inhibition terms in the global rate expressions were also found to be reasonably reliable although the surface reaction rates required calibration with experimental data.
Book Review: Automotive Quality Systems Handbook
Authors: Watson R. A.
Published: October 2002

The International Standards Organization, ISO, published in 1999 the results of the IATF discussions as ISO/TS16949, Quality Systems—Automotive Suppliers, particular requirements for the application of ISO 9001:1994. This new document incorporates the specific automotive industry system certification elements found in national standards such as QS9000 (USA), AVSQ ‘94 (Italy), EAQF ‘94 (France) and VDA6 (Germany).
Friction behaviour and squeal generation of disc brakes at low speeds
Authors: Eriksson M , Jacobson S
Published: October 2002

Brake squeal is a subtle phenomenon, apparently occurring according to some random behaviour. Two stops during nominally equal conditions may act completely differently concerning brake squeal. Further, without changing the nominal conditions, a brake may shift from silent to squealing. This confused behaviour, in the otherwise stable and well-controlled brake system, can only be explained by the characteristics of the friction between the pad and the disc. A test series was tailored in order to increase the understanding of the friction characteristics with respect to two suggested squeal mechanisms. It included braking with continuously increasing and decreasing brake pressure at constant speed and vice versa. This concept minimizes the influence of temperature and run-in on the coefficient of friction. It was found that no squeals were generated below a coefficient of friction of 0.4, that braking conditions with a high coefficient of friction were related to more frequent squeal generation and that pads with a negative friction-velocity behaviour did not invariably show a higher squeal propensity. Furthermore, it is concluded that squeal-related friction characteristics can only be measured in a timescale similar to that of a squeal, i.e. on the 0.1 ms scale, owing to the different speeds of processes influencing the friction force. A higher lateral resolution over the pad of the friction measurement than currently used in brake testing is also required.
A theoretical study of the yaw/roll motions of a multiple steering articulated vehicle
Authors: Wu D-H
Published: October 2002

The objective of this paper is to present a theoretical analysis of the yaw/roll motion for an actively multi-axle steering articulated vehicle. The roll instability of articulated vehicles is one of the most serious problems for the vehicle's occupants. Therefore, it is necessary to develop both yaw and roll responses in a more comprehensive model to obtain an accurate result. In this study, a five-degree-of-freedom articulated vehicle with multiple steering mathematical model and the basic analytical results of the yaw/roll performance characteristics are presented. The use of an additional steering axle on the towed unit is shown to increase the directional stability, to reduce the roll angle and to minimize the lateral force during steady turning. Moreover, the effect of roll steer about the lateral force in steady state turning, lane change simulation and the influence of roll steer coefficients and location of the additional steer axle on critical speed are also discussed and illustrated. This study does not address the feasibility of implementing these systems or limiting of the driver using these systems.
Particle image velocimetry measurement of in-cylinder flow in internal combustion engines-experiment and flow structure analysis
Authors: Li Y , Zhao H , Peng Z , Ladommatos N
Published: October 2002

A cross-correlation digital particle image velocimetry (PIV) system has been developed and applied to study the in-cylinder flow in a single-cylinder engine with a production-type cylinder head. The PIV system set-up and its optimization are described in the first part of the paper. Two-dimensional velocity distributions measured over 100 cycles are analysed to obtain ensemble-averaged mean and fluctuating velocities, the turbulent length scale, vorticity and strain rate distribution in the measurement plane. In particular, a spatial filtering scheme is developed in order to obtain the cycle-resolved velocity measurements. The cycle-resolved analysis shows that the low-frequency velocity fluctuation component (i.e. cyclic variation) is mainly responsible for the spatial variation in velocity and turbulent kinetic energy distributions. The integral length scale calculated from the PIV data is between 6 and 10 mm and the strain rate is estimated to be within 1000 s-1 in most areas of the measurement plane.
Wear of diesel engine inlet valves and seat inserts
Authors: Lewis R , Dwyer-Joyce R S
Published: October 2002

Valve wear has been a problem to engine designers and manufacturers for many years. Although new valve materials and production techniques are constantly being developed, these advances have been outpaced by demands for increased engine performance. The aim of this work was to establish the effect of engine operating parameters on diesel engine inlet valve recession and to screen potential new seat materials using test apparatus designed to simulate the loading environment and contact conditions to which a valve and seat are subjected. These data were then used, along with the mechanisms of wear identified during previous work [1-3], to develop a quantitative model for predicting valve recession. Valve recession was shown to increase with combustion loading, valve closing velocity and misalignment of the valve. Drip feed lubrication of the valve/seat interface reduced valve recession, on the material combination tested, by a factor of 3.5. The lubricant, however, was supplied in a larger amount and at a lower temperature than would be experienced in an engine. Two materials, of those tested, stand out as having improved wear resistance. These are maraging steel and ductile cast iron. Both gave significantly higher wear resistance than the other seat materials tested. The semi-empirical valve recession model, based on the fundamental mechanisms of valve and seat wear, provides a good approximation of valve recession for both engine tests and tests run on the hydraulic loading apparatus. Modelling of a diesel engine test indicated that impact was the major cause of valve recession.
A test method for the quantification of on-centre handling with respect to cross-wind
Authors: Dettki F
Published: October 2002

During the development process of a new passenger car chassis, certain aspects of the driving dynamics concerning comfort and handling receive particular attention. During this process it is crucial to maintain basic characteristics. One of these basic characteristics is the straight-ahead stability. It is also important that the driver can feel this straight-ahead stability through the steering wheel. With the wording ‘on-centre handling’, both aspects are addressed: the objective straight-ahead stability and the subjective feeling for very small steering wheel movements. This article presents a proposal for the objective description of on-centre handling. A new method is introduced to allow the calculation of characteristic values for the straight-ahead stability without any driver influence. The principle of this new method consists of a comparison between the measured and the calculated yaw velocities. The calculated yaw velocity results from a modified single-track model. The yaw velocity error is the result of the difference between the calculated and measured yaw velocities. After this error is calculated it will be plotted versus the measured disturbance variables (wind, lateral inclination). The vehicle response is more sensitive to the disturbance for a larger gradient of this graph. For the complete description of on-centre handling, it is necessary to characterize the steering feel. Characteristic values are introduced to describe the steering feel and the corresponding vehicle reaction.
An automated driver based on convergent vector fields
Authors: Gordon T J , Best M C , Dixon P J
Published: October 2002

This paper describes a new general framework for the action of an automated driver (or driver model) to provide the control of longitudinal and lateral dynamics of a road vehicle. The context of the problem is assumed to be in high-speed competitive driving, as in motor racing, where the requirement is for maximum possible speed along a track, making use of a reference path (racing line) but with the capacity for obstacle avoidance and recovery from large excursions. While not necessarily representative of a human driver, the analysis provides worthwhile insight into the nature of the driving task and offers a new approach for vehicle lateral and longitudinal control; it also has applications in less demanding applications such as Advanced Cruise Control systems. As is common in the literature, the driving task is broken down into two distinct subtasks: path planning and local feedback control. In the first of these tasks, an essentially geometric approach is taken here, which makes use of a vector field analysis. At each location x the automated driver is to prescribe a vector w for the desired vehicle mass centre velocity; the spatial distribution and global properties of w( x) provide essential information for stability analysis, as well as control reference. The resulting vector field is considered in the context of limited friction and limited mass centre accelerations, leading to constraints on ∇ w. Provided such constraints are satisfied, and using suitable adaptation of w( x) when required, it is shown that feedback control can be applied to guarantee stable asymptotic tracking of a reference path, even under limit handling conditions. A specific implementation of the method is included, using dual non-linear SISO (single-input single-output) controllers.
The development of a material model for cast iron that can be used for brake system analysis
Authors: Koetniyom S , Brooks P C , Barton D C
Published: October 2002

This paper describes the methodology and reports the results of detailed thermomechanical finite element analyses of cast iron brake discs under repeated high g braking conditions. The thermal analysis allows for heat loss from the vanes in a back-ventilated disc design as well as heat transfer to other parts of the brake assembly. The cast iron material properties required for the non-linear structural analysis are generated by mechanical tests on samples cut from the brake disc. The material model developed by the authors allows for the variation of flow stress with temperature and for the different yield properties of cast iron in tension and compression. The finite element results, derived from a preliminary investigation, indicate regions of high plastic strain accumulation which may lead to disc crazing and/or cracking and enable comparisons to be made between back- and front-vented rotor designs.
An experimental study on engine performance with high ignition energy
Authors: Song J , Sunwoo M
Published: October 2002

The objective of this research is to investigate the improvement of engine performance with high ignition energy. In order to study this objective, two different spark ignition engines are employed and four different ignition systems are adopted. The ignition energy, combustion pressure, exhaust gases and fuel consumption are measured to evaluate engine performances. In addition, the heat release rate, mass fraction burned and coefficient of variation (COV) of indicated mean effective pressure (IMEP) are calculated with the measured pressures. The results reveal that high ignition energy shortens the combustion duration, improves the engine stability and reduces fuel consumption. When a higher ignition energy is applied to a lean mixture, the emission of hydrocarbons (HC) is reduced while an engine with the conventional ignition energy produces higher HO emission. A faster heat release rate and a higher mass fraction burned also result. When the same amount of ignition energy is applied to a lean mixture, the burning velocity is slow as the discharge duration becomes longer, but the COV of IMEP is improved.
Automotive test drive cycles for emission measurement and real-world emission levels-a review
Authors: Samuel S , Austin L , Morrey D
Published: October 2002

The emission levels produced by any vehicle are dependent on the mode of operation of the vehicle and technology behind the vehicle design. The test drive cycles employed to measure the emissions produced by vehicles should adequately represent the real-world driving pattern of the vehicle to provide the most realistic estimation of these levels. However, there is increasing concern about the representative drive cycles used by the various vehicle certification and regulatory authorities. This paper reviews the various drive cycles used for gasoline engine vehicles in Europe and the United States, and the impact of various factors and their influence on real-world emission levels. The proposed new drive cycles of the United States and Europe are considered. From the work reviewed, it can be concluded that the amount of pollutant levels from automotive vehicles are underestimated because of the characteristics of the existing drive cycles. While much work remains to be done with the development of new drive cycles to represent real-world driving patterns, some useful conclusions can be drawn regarding the impacts of the factors reviewed here. The impacts of the factors reviewed in this paper can be characterized to improve estimations and simulations of the real-world emission levels of the vehicle.
Potential of thermal methods for catalyst on-board diagnosis
Authors: Tsinoglou D N , Koltsakis G C
Published: October 2002

Reductions in vehicle-related air pollution are expected to be supported by improved and efficient monitoring strategies. The on-board detection of catalyst failure is a key issue in this respect and is already fully prerequisite by the US and European legislation. Despite the progress made in the field so far, more efforts are required to develop simple and reliable on-board diagnosis (OBD) and on-board measurement systems for catalytic converters. This paper presents an OBD concept and methodology based on the measurement of catalyst exotherm. After a review of the main existing OBD systems, the theoretical approach of the method is analysed. The characterization of the catalyst condition is made by a specially defined performance index, which is continuously calculated on board. The capabilities of the presented technique are displayed on the basis of experiments performed with two catalysts of different ageing levels, as well as a simulation of a large number of aged catalysts. The results indicate that the presented methodology may be successfully applied to conventional underbody as well as to alternative catalyst systems (pre-converters and electrically heated catalysts) for OBD purposes.
A theoretical investigation of two possible modifications to reduce pollutant emissions from a diesel engine
Authors: Gao Z , Schreiber W
Published: October 2002

The goal of the study is to present and to evaluate theoretically two strategies for reducing simultaneously both particulate and NOx emission from a compression-ignited, direct injection engine. The emission reduction strategies to be considered here include auxiliary exhaust gas injection (AEGI) and a combination of exhaust gas recirculation (EGR) and AEGI. The auxiliary gas injection (AGI) process consists of the injection of a gas directly into the combustion chamber of a diesel engine during the combustion stroke to enhance fluid mixing. Increased mixing during the combustion process can lower the emission of both soot and NOx. AEGI is a process whereby exhaust gas is the injected gas used in AGI. To predict the effect of AEGI on diesel engine combustion and emission, a gas injection model was developed and used with a multidimensional simulation computer code, KIVA. The program is used to evaluate the combined effect of AEGI and EGR on pollutant emissions in a Caterpillar diesel engine. The results demonstrate that the injection timing of AEGI affects soot emissions quite differently to NOx emissions. A combination of EGR and AEGI is found to be more effective than AEGI alone for the maximum simultaneous reduction of soot and NOx emissions. It is predicted that the EGR and AEGI combination can reduce both particulate and NOx emissions by almost 50 per cent over baseline.
A theoretical investigation of a prototype active roll control system
Authors: Darling J , Ross-Martin T. J.
Published: October 2002

This paper describes a simulation study conducted as part of the development of a hydraulic active roll control suspension. The system is based upon roll bars with integral closed loop position controlled hydraulic rotary actuators supplied with flow by a single proportional valve. A theoretical analysis of the fundamental characteristics of the system is presented together with the simulation implementation. System performance is examined, parameter sensitivity studies are undertaken and a number of practical measures to enhance performance are considered.

The roll control system was largely insensitive to hydraulic system changes, control valve bandwidth being the most important parameter. Speed dependent gain scheduling of the forward path actuation system roll moment controller was shown to partially overcome the problem of vehicle dynamics which change with forward speed. A comparison of actuator displacement and actuator differential pressure feedback systems demonstrated that while the roll control performance of the former system was superior, the ride performance was inferior.
Misalignment equation for the Van Doorne metal pushing V-belt continuously variable transmission
Authors: Robertson A. J. , Tawi K. B.
Published: October 2002

The existence of belt/pulley misalignment in the Van Doorne metal pushing V-belt continuously variable transmission (CVT) has always been recognized by researchers and the manufacturers themselves. However, its effect has always been assumed to be negligible and search through the literature reveals no work published so far to verify this assumption. Misalignment of the belt may increase losses and the need to improve efficiency is now of paramount importance. This paper is an initial effort by the authors to address this area and study the geometrical behaviour of the belt misalignment theoretically. An equation to represent this geometrical behaviour has been developed and it is able to calculate the magnitude and position of the belt misalignment at different speed ratios and at different assembled zero belt misalignment speed ratios. The condition necessary to minimize the magnitude of the belt misalignment has been determined. Verification of the equation was obtained by using a solid modeller from a Unigraphics Version 10.4.0 computer aided design (CAD) package. It is intended that the findings from this study will enable the authors to study further the effect of misalignment on the efficiency and performance of the transmission.
An experimental and theoretical investigation into the design of an active suspension system for a racing car
Authors: Purdy D. J. , Bulman D. N.
Published: October 2002

The well-established quarter car representation is used to investigate the design of an active suspension system for a racing car. The work presented is from both a practical and theoretical study. The experimental open-loop and passive responses of the suspension system are used to validate the model and estimate the level of damping within the system. A cascade control structure is used, consisting of an inner body acceleration loop and an outer ride height loop. Comparisons are made between the experimental results and those predicted by the theory.

During the 1980s and early 1990s a number of Formula 1 teams developed active suspension systems to improve the performance of cars. Little detail was published about these systems because of the highly competitive nature of the application. Some of these systems were very sophisticated and successful. Because of this, speed increased considerably and because of the costs involved, the difference in performance between the lower and higher funded teams became unacceptable. For this reason, the governing body of motor sport decided to ban active suspensions from the end of the 1993 racing season. Both authors of this paper were involved with different racing teams at that time, and this paper is an introduction to the very basic philosophy behind a typical active system that was employed on a Formula 1 car.
Vision-based motion measurement by directly extracting image features for vehicular steering control
Authors: Hsu J-C , Lin R-H , Yeh E C
Published: October 2002

An image sensing technique is developed using image plane analysis to measure the vehicular motion variables through an in-vehicle camera. A new measurement model is derived to directly connect the image features of vanishing point and base point with the desired motion variables comprising heading angle, lateral deviation, yaw rate and sideslip angle of the vehicle. These are useful in vehicular steering control applications such as automatic and four-wheel steering systems for providing feedback motion information in a convenient way. In order to test the proposed vision-based measuring scheme, a computerized road scene is simulated as the test sample using a newly proposed model for curvature-based road generation. Finally, experimental works are performed using the real road scene to verify the image sensing method. Consistent results are obtained by comparing with other measurements from a yaw rate gyro and from vehicular traces left on the road.
Characteristics of scavenging flow in transfer ports of a motored two-stroke engine
Authors: Weclaś M , Melling A , Durst F
Published: October 2002

A real two-stroke engine [specifically an Orbital Combustion Process X (OCP-X) engine] was optically modified for application of laser Doppler anemometry (LDA) and flow visualization. Two velocity components were measured in two transfer ports of the motored engine. Spatial and temporal distributions of velocity indicated that the scavenge flow was very complex, highly non-uniform across the transfer ports, and strongly time dependent with respect to the port opening and closing periods. Mean velocities averaged over these two periods characterize the scavenge flow in the transfer ports but do not represent the velocity peaks at the port opening and closing, respectively. Effects of the exhaust valve in the exhaust port and of depression applied to the exhaust port on the temporal distribution of scavenge flow in transfer ports were significant only for a high enough pressure difference between the crankcase and the exhaust.
Development of a natural gas spark ignition engine for optimum performance
Authors: Das A , Watson H C
Published: October 2002

A 4 litre displacement, six cylinder, fuel injected petrol engine was modified to natural gas (NG) fuelling. Experimental investigation was carried out with various mixture controls and compression ratios over a wide range of operating conditions. As a strategy for combustion chamber shape modification, the compression ratio was raised with simultaneous enhancement of in-cylinder turbulence through squish motion. A fast burning chamber for the combustion of lean mixtures of natural gas and air was developed. Brake thermal efficiency in excess of 40 per cent and brake torque in excess of the peak base torque with petrol were achieved. The research provides the foundation for the implementation of NG cars that will emit only about 65 per cent of the carbon dioxide (CO2) of their petrol engine counterparts, with the prospect of extending the limited range of NG cars by up to one-third and producing low hydrocarbon (HC) and nitrogen oxide (NOx) emissions.
Influence of tractor—trailer interaction on assessment of road damaging performance
Authors: Cole D J , Cebon D
Published: October 2002

The influence of dynamic interaction between tractor and trailer on the assessment of the road damaging performance of heavy goods vehicles is investigated using simple mathematical models. Tractor and trailer damage indices are used to quantify the ‘in-service’ road damaging performance of a simulated fleet of vehicles with parametric variations typical of highway traffic in the United Kingdom.

Simulated results of assessment tests on individual tractor—trailer combinations are correlated with the performance of the simulated vehicle fleet. The main aim is to establish the characteristics of a ‘standard’ semi-trailer to be used in the assessment of tractors, and a ‘standard’ tractor for testing semi-trailers. It is found that measurement of suspension ‘frequency’ gives the poorest correlation with the damage indices, while the ‘dynamic aggregate force coefficient’ gives the best correlation. Correlation achieved when assessing trailers is higher than when assessing tractors. Optimum specifications for standard test tractors and trailers to maximize test accuracy are determined.
Development of a modified diesel engine cycle
Authors: Zhou P L , Qian Y Q
Published: October 2002

This paper presents an investigation of a novel type of diesel engine cycle, an approximate constant pressure cycle. The prototype engine is called the diesel engine with oil cushioned piston (DEOCP). In contrast to conventional engines, the DEOCP has a variable cylinder volume which is controlled automatically by the engine's cylinder pressure. The variable cylinder pressure is achieved by inserting a hydraulic cylinder into the engine's piston rod. The engine cylinder pressure is thus self-controlled and an ideal constant pressure cycle can theoretically be achieved.

Computer simulations and engine tests have shown that the DEOCP distinguishes itself with high cycle efficiency, improved low-load performance and good starting ability. A detailed theoretical analysis and test results are presented in the paper, as well as a discussion of existing problems and possible further developments. Development of the diesel engine with oil cushioned piston could break the limit of cycle efficiency of conventional engines, hence opening a new avenue for diesel engine development.
Case Study: Vibration analysis for the design of a high-speed generator for a turbo-electric hybrid vehicle
Authors: Leontopoulos C , Robb D. A. , Besant C. B.
Published: October 2002

The project relates to the design and development of a prototype high-speed turbo-generator as the thermal engine in a series hybrid vehicle. The substantial benefit of the turbo-generator against a diesel generator lies in the very high power-weight, power-volume ratio and renders itself particularly attractive for use in hybrid vehicle applications. However, to achieve a 50 kW power output, the turbo-generator has to have an operating speed of 60 000 r/min and thus important mechanical problems have to be solved. The core of this study addresses the requirement for an adequate understanding of rotor-dynamic behaviour by combining the results from both analytical and practical techniques. The assessment of modal testing, finite element analysis and vibration-condition monitoring, their feedback within the design-make-and-test procedure and the practical compromises and design constraints are presented and a design methodology is formulated. It is concluded that, under certain conditions, the prototype generator can be directly coupled to a small gas turbine, can operate safely and can produce the required power output.
Vehicle dynamics using a limit surface treatment of the tyre-road interface
Authors: DiMaggio S. J. , Bieniek M. P.
Published: October 2002

A new method of dealing with the force-producing mechanism at the tyre—road interface is presented. The tyre model consists of a representation of the tyre elasticity and the relations between the interface forces and the contact patch displacement. These relations are described in terms of the ‘tyre limit surface’. The model appears to be capable of reproducing the tyre behaviour under both free-rolling and fully locked wheel conditions. A satisfactory agreement has been obtained between the available experimental data on the force versus slip parameters and the predictions of the present model. Applications to two problems of vehicle dynamics, oversteer versus understeer behaviour and motion with locked rear wheels, are presented.
Hybrid vehicle simulation for a turbogenerator-based power-train
Authors: Leontopoulos C , Etemad M. R. , Pullen K. R. , Lamperth M. U.
Published: October 2002

The potential of the turbogenerator-based power-train for hybrid vehicles is described. Data from a small gas turbine, a prototype high-speed generator and an advanced lead-acid battery pack show that the ‘turboelectric’ concept is feasible and can provide a viable road transport solution which will comply with the stringent environmental legislation. The simulation results show improved overall vehicle efficiencies due to the implementation of regenerative braking capability. Most importantly the lean combustion of the gas-turbine engine with a suitable energy control strategy can provide lower emissions than ultra-low-emission vehicle (ULEV) limits, while an acceptable zero-emissions vehicle (ZEV) driving range can be achieved for city centres.
Automotive timing belt life laws and a user design guide
Authors: Childs T. H. C. , Dalgarno K. W. , Day A. J. , Moore R. B.
Published: October 2002

The paper presents a computer-based guide of the effect of layout and loading (tension and torque) on the timing belt life and uses it to show the sensitivity of life to changed conditions in an automotive camshaft drive. The predictions are in line with experience. The guide requires belt property information, such as the tooth and tension member stiffness, the friction coefficient between the belt lands and pulleys and the pitch difference from the pulley, in order to calculate the tooth deflections caused by the belt loadings on the various pulleys in the layout. It also requires information on how the belt life depends on the tooth deflections. Experimental data are presented on the life—deflection relations of a commercial automotive timing belt tested between 100 and 140°C, although the bulk of the data has been obtained at 120°C. Four different life laws have been found, depending on whether the failure-initiating deflection occurred on a driver or a driven pulley, and whether at entry to or exit from the pulley. Theoretical analysis of the tooth loading in the partial meshing state shows that, in three cases out of the four, the different life-deflection laws transform to a single relation between the life and the tooth root strain. The exception is failure caused by driven entry conditions; work is continuing to understand better the causes of failure in this circumstance.
Slower, smaller and lighter urban cars
Authors: Moriarty P , Honnery D
Published: October 2002

Rising global car ownership levels generate a variety of problems, including traffic congestion, oil depletion, air pollution and traffic accidents. These problems are usually most severe in urban areas. This paper examines the potential for large reductions in maximum speed, size and mass of urban cars to ameliorate these problems. It is found that cutting maximum speeds would significantly lower the frequency and severity of traffic accidents, especially in the third world, where fatality rates per vehicle are very high. If cars carried a maximum of two to four persons, car length and width could be reduced. Such cars would require smaller lane widths and less parking space, thus helping to ease traffic congestion. The combination of smaller and slower vehicles means that car mass can also be greatly reduced, which in turn reduces fuel use and, with it, urban air pollution and carbon dioxide emissions.
Reed valve modelling in a computational fluid dynamics simulation of the two-stroke engine
Authors: Cunningham G , Kee R. J. , Kenny R. G.
Published: October 2002

A method of modelling the crankcase induction process through the integration of computational fluid dynamics (CFD) and one-dimensional engine simulation methods is described. A study of flow in the crankcase of a typical two-stroke engine by Cunningham et al. [1] has led to the development of a method for predicting and duplicating the motion of the reed valve in the inlet system. The response of the reed valve was predicted by a one-dimensional mathematical model and the corresponding inlet flow geometry that results from the reed motion was accommodated via a mesh movement routine in the CFD. The resultant hybrid model showed good correlation with the reed lift, crankcase pressure and delivery ratio predicted by a proven one-dimensional engine simulation code. The predicted velocity fields from the CFD also provided a more detailed view of the processes that occur in and around the reed valve, including the backflow prior to reed closure and the flow reversal which characterizes the two-stage lift profile of the reed. The results from this model show that it should now be possible to create a complete CFD representation of a two-stroke engine by including these techniques in the conventional in-cylinder models.
The effects of different gasoline blends doped with used engine oil on the forming tendency of simulated intake—valve deposits
Authors: Haji-Sulaiman M. Z. , Mat-Isa F
Published: October 2002

The effects of gasoline composition doped with a trace amount of used engine oil on the formation of simulated intake valve deposit have been investigated. Studies were performed using a bench top simulator. Oxygenated gasoline has been found to exhibit a high deposit-forming tendency. In addition to the amount, the nature of the deposit formed also depends on the type of fuel used. For oxygenated fuel, a dry carbonaceous deposit is usually formed instead of the polymeric deposit that is commonly obtained from non-oxygenated fuel.
Non-parametric models in the monitoring of engine performance and condition: Part 1: Modelling of non-linear engine processes
Authors: Jacob P. J. , Gu F , Ball A. D.
Published: October 2002

This paper proposes the use of radial basis function (RBF) networks in the modelling of non-linear engine processes. A pertinent application of such a model is the reconstruction of cylinder pressure based upon the instantaneous angular velocity of the engine crankshaft. Distinction is made between parametric and non-parametric models and applications to which each is suited. The structure of an RBF model is presented and the use of this model in combustion pressure reconstruction is discussed. The paper concludes with a treatment of the practicalities associated with the implementation of an RBF model to typify a non-linear engine process.
Energy consumption analysis of heavy-duty vehicles for transient emissions evaluation on chassis dynamometer
Authors: Wang W. G. , Lyons D. W. , Clark N. N. , Luo J. D.
Published: October 2002

In order to acquire vehicle emissions and fuel economy by driving a vehicle on a chassis dynamometer, it is imperative that the chassis dynamometer should exactly simulate the road experience of the vehicle. In this paper, the modelling of a heavy-duty vehicle energy consumption both on the road and on a chassis dynamometer was developed and implemented by using two driving cycles. Road coast-down tests of a vehicle were conducted to obtain a road load equation of the vehicle. Its companion chassis dynamometer coast-down tests were aimed to estimate the characteristics of the dynamometer-vehicle system. Power absorber settings were achieved that duplicate the vehicle road load in the dynamometer testing. Comparing the measured energy of the vehicle between driving cycles on the chassis dynamometer and the calculated energy on the road, it is shown that the West Virginia University (WVU) transportable heavy-duty chassis dynamometer is successful in simulating the vehicle road load conditions when conducting emissions testing.
Effect of an inter-ring crevice on unburned hydrocarbon emissions in a spark-ignition engine
Authors: Kim C. G. , Choi S. M. , Bae C. S.
Published: October 2002

The effect of the inter-ring crevice, the volume between the top and the second piston rings, on unburned hydrocarbon (UHC) emission was experimentally investigated. The ultimate goal of this study was to reduce the level of UHC emission by minimizing the effect of the inter-ring crevice. For this purpose, the unburned mixture trapped in the inter-ring crevice was extracted to the crankcase during the late period of expansion and the early period of the exhaust stroke through the engraved grooves on the lower part of the cylinder wall. The extraction of the mixture resulted in significant reductions in UHC emission by 23 per cent at maximum over a range of speeds (1250-3500 r/min) and loads (185-556 kPa, b.m.e.p.), without any losses of efficiency and power. This experimental study has confirmed the importance of the inter-ring crevice on UHC emission in a spark-ignition (SI) engine.
Clonk: An onomatopoeic response in torsional impact of automotive drivelines
Authors: Menday M. T. , Rahnejat H , Ebrahimi M
Published: October 2002

Vehicular driveline is a lightly damped non-linear dynamic system that is prone to noise and vibration response when subjected to excitation. There are many sources of excitation such as torsional impact caused by the take-up of backlash in the powertrain system. Such sources of excitation exist in transmission backlash, in driveline splines and in pinion-ring gear contact in the differential. Abrupt application or release of the throttle in slow moving traffic or rapid engagement of the clutch can be followed by an onomatopoeic response of the driveshafts, referred to in the industry as clonk. This is a disagreeable, audible and tactile response in some vehicles and can also coincide with every cycle of low-frequency longitudinal vehicle response, commonly referred to as shuffle or shunt. This paper describes the phenomenon of clonk and investigates its occurrence both by an experimental technique and by detailed modal analysis of driveshaft pieces. It is shown that finite element predictions agree well with the experimental findings and that the high-frequency structural modes can lead to discernible radiated noise. The preliminary findings reported here point to a need for a more detailed elasto-acoustic analysis.