LATEST ARTICLES
Details of the latest articles published in the Journal. Includes the most recent InPress papers (uncorrected proofs of accepted papers awaiting publication in a Journal issue).
Date: Tue, 06 Jul 2010 18:39:35 GMT
It is a well-known fact that braking is one of the most important factors in customer satisfaction and a key factor in the voice of the customer (VOC). The VOC has to be translated into engineering specifications in due course and various methods have been developed. Current engineering specifications utilize only a few discrete points on the pedal force (PF), pedal travel (PT), and response time (RT) curves owing to the multi-dimensional nature of these curves and thus may not represent the entire curves well. Principal-component analysis (PCA) is applied in order to analyse the entire shapes of the three curves and to identify the underlying variation modes. Then, buyer satisfaction scores from a mail survey are regressed on the variation modes. Finally, the ideal shapes of the PF, PT, and RT curves are developed for the sport segment, the coupé and sedan segment, and the truck segment to aid new brake system and vehicle design. Translating the VOC from marketing research into engineering specifications is a critical step and PCA is a valuable tool for this translation.
- Content Type Journal Article
- DOI 10.1243/09544070JAUTO1585
- Authors
- S-D Lee, Troy, Michigan, USA
- S-L Kim, Troy, Michigan, USA
Date: Tue, 06 Jul 2010 18:39:34 GMT
The use of the second law of thermodynamics is a powerful means for assessing the performance of engines, and is the only way to determine the destruction of exergy. This work has examined a turbocharged, spark-ignition engine in some detail, and in particular, has quantified the effects of varying the engine cylinder heat transfer.
A thermodynamic simulation was developed to investigate these effects from both the first law and second law perspectives. The engine used for this study was a 3.8 l, V-6, turbocharged engine with an intercooler. The engine was examined for various levels of heat transfer. The exergy values associated with the components of the turbocharger along with the engine components were quantified as a percentage of fuel exergy. For the base case operating conditions (full load, 2000 r/min) about 20.5 per cent of the exergy was destroyed during the combustion process, and the turbocharger components were responsible for less than 1 per cent of the exergy destruction. As the heat transfer level decreased, work increased only slightly while the exhaust energy and exergy increased much more significantly. Although engine performance was altered as the heat transfer level was changed, the destruction of exergy remained nearly constant.
- Content Type Journal Article
- DOI 10.1243/09544070JAUTO1535
- Authors
- V J Lawand, Department of Mechanical Engineering, Texas A&M University, College Station, TX, USA
- J A Caton, Department of Mechanical Engineering, Texas A&M University, College Station, TX, USA
Date: Tue, 06 Jul 2010 18:39:33 GMT
Cyclic variability (CV) in combustion has been studied over many years and is still an active area of research. Despite the application of many analytical tools, including, in more recent years, those connected with the study of non-linear dynamic systems, CV remains a challenging subject. In the past, most researchers into CV have presented their findings in the form of overall statistical measures. However, it is felt that perhaps more attention needs to be paid to sequences of combustion cycles on a detailed cycle-to-cycle basis, particularly where the aim is to try to formulate a control mechanism to reduce CV, and that sonification combined with self-similarity plots provides a useful tool to facilitate such an approach. The purpose of this paper is to introduce sonification to automotive engineers, who may be unfamiliar with sonification, and to give an example of its implementation and application in the study of CV in internal combustion engines.
- Content Type Journal Article
- DOI 10.1243/09544070JAUTO1504
- Authors
- R Tily, Department of Mechanical Engineering, University of Bath, Bath, UK
- C J Brace, Department of Mechanical Engineering, University of Bath, Bath, UK
Date: Tue, 06 Jul 2010 18:39:33 GMT
One of the primary features of a micro-hybrid vehicle is the automatic shutdown and restart of the engine to avoid engine idling when the vehicle is at rest. The system strategy and its calibration have important significance on the driveability of the vehicle in terms of the vehicle launch behaviour.
An unsatisfactory vehicle launch is defined as an inferior launch performance of the vehicle resulting in a stalled engine, a launch with negative vehicle acceleration, and an aborted engine restart due to the inability of the vehicle to provide torque as demanded by the user. In this research, micro-hybrid system optimization for reduction in the percentage of impaired vehicle launch events in real-world usage has been conducted on a start–stop vehicle. The design for the six-sigma process was followed for the optimization study. A high-fidelity electrical and powertrain system and a longitudinal vehicle dynamics model for a start–stop vehicle have been developed. The model has been validated with experimental data. The drivers' behaviour for vehicle launch events from a customer clinic of start–stop vehicles has been used as an input to the model. Using design of experiments, the system has been optimized to maximize the percentage of successful launch events in real-world usage.
- Content Type Journal Article
- DOI 10.1243/09544070JAUTO1496
- Authors
- A Dhand, AVL Powertrain UK Ltd, Southfields Business Park, Basildon, Essex, UK
- B-K Cho, AVL Powertrain UK Ltd, Southfields Business Park, Basildon, Essex, UK
- A Walker, AVL Powertrain UK Ltd, Southfields Business Park, Basildon, Essex, UK
- D Kok, Ford Motor Company, Basildon, Essex, UK
- M Burgess, Ford Motor Company, Basildon, Essex, UK
- B Semar, Ford Motor Company, Basildon, Essex, UK
Date: Tue, 06 Jul 2010 18:39:32 GMT
This paper presents two non-linear observer designs with different robustness to estimate engine selective catalytic reduction (SCR) ammonia coverage ratio. The observers estimate the SCR catalyst ammonia storage (or coverage ratio) based on the available measurements of NOx, NH3, and temperature. An extended Kalman filter) is proposed to eliminate the NOx sensor cross-sensitivity to ammonia. A sliding mode observer technique was employed for the design. The robustness of the observers with respect to sensor measurement uncertainties was theoretically analysed. FTP75 test cycle simulation results show the robustness and estimation accuracies of the different observers in the presence of different measurement errors/uncertainties.
- Content Type Journal Article
- DOI 10.1243/09544070JAUTO1482
- Authors
- M-F Hsieh, Department of Mechanical Engineering, Ohio State University, Columbus, Ohio, USA
- J Wang, Department of Mechanical Engineering, Ohio State University, Columbus, Ohio, USA
Date: Tue, 06 Jul 2010 18:39:32 GMT
Homogeneous charge compression ignition (HCCI) engines have low nitrogen oxide and particulate matter engine-out emissions but have higher unburned hydrocarbon and carbon monoxide emissions than the conventional spark ignition (SI) and diesel engines do. Only for sufficiently high exhaust gas temperatures can an exhaust after-treatment be used; thus a low exhaust gas temperature in certain operating conditions can limit the operating range in HCCI engines. The influences of the engine conditions on the exhaust gas temperature in a single-cylinder experimental engine are investigated at 340 steady state operating points. The variation in the exhaust gas temperature is also studied under transient conditions and during mode switching between SI and HCCI combustion. For the conditions tested, a significant number of data have an exhaust gas temperature below 300 °C which is below the light-off temperature of typical catalytic converters on the market. Three different categories of engine variables are recognized and classified by how the exhaust temperature is affected by changing that variable. The first category is defined as the primary variables (e.g. the intake pressure and the fuel octane number) for which the location of ignition timing is the dominant factor in influencing the exhaust temperature. The other groups include compounding variables such as the engine speed and opposing variables such as the intake temperature, the coolant temperature, and the equivalence ratio. In addition, experimental results show that the exhaust temperature for HCCI engines is not strongly dependent on the engine load, unlike that for SI engines where the engine load is a main factor in determining the exhaust temperature.
- Content Type Journal Article
- DOI 10.1243/09544070JAUTO1473
- Authors
- M Shahbakhti, Department of Mechanical Engineering, KNT University of Technology, Tehran, Iran
- A Ghazimirsaied, Department of Mechanical Engineering, University of Alberta, Edmonton, Canada
- C R Koch, Department of Mechanical Engineering, University of Alberta, Edmonton, Canada
Date: Tue, 06 Jul 2010 18:39:31 GMT
The steering-wheel–steering-column assemblies fitted in automobiles must have a high energy absorption performance in order to minimize occupant chest injuries in the event of a collision. This paper proposes a novel built-in energy-absorbing (EA) component which causes the impact load transmitted to the occupant to vary in accordance with the crash severity and the occupant mass. A finite element (FE) model of the steering-column system is constructed on the basis of realistic product computer-aided design data, and a series of LS-DYNA simulations are performed to examine the dynamic responses of the steering wheel and steering column in body block impact tests performed using body blocks of different weights. The validity of the FE model is confirmed by comparing the numerical results for the torso force profile over the duration of the impact with the experimental results obtained in two standard body block tests. The validated model is then used to examine the energy absorption performance of the proposed EA device consisting of a hollow cylindrical tube patterned with an array of circular openings. The simulations focus specifically on the effects of the total hole-opening area, the cylinder thickness, and the cylinder material on the torso force profile over the duration of the impact. It is shown that, given an appropriate specification of the design parameters, the proposed EA device satisfies the peak load requirement specified in the FMVSS 203 standard and absorbs 163 J and 235 J of the impact kinetic energy for body block weights of 24 kgf and 34 kgf respectively.
- Content Type Journal Article
- DOI 10.1243/09544070JAUTO1471
- Authors
- D-S Liu, Department of Mechanical Engineering, National Chung Cheng University, Ming-Hsiung, Chia-Yi, Republic of China
- C Y Tu, Department of Mechanical Engineering, National Chung Cheng University, Ming-Hsiung, Chia-Yi, Republic of China
- C-M Fan, Department of Mechanical Engineering, National Chung Cheng University, Ming-Hsiung, Chia-Yi, Republic of China
- S-S Yeh, Department of Mechanical Engineering, National Chung Cheng University, Ming-Hsiung, Chia-Yi, Republic of China
- W-F Wang, GSK InTek Co., Ltd, Huatang, Chanhua, Republic of China
- C-L Hsieh, GSK InTek Co., Ltd, Huatang, Chanhua, Republic of China
Date: Tue, 06 Jul 2010 18:39:30 GMT
Jet ignition and direct fuel injection are potential enablers of higher-efficiency cleaner internal combustion engines (ICEs), where very lean mixtures of gaseous fuels could be burned with pollutants formation below Euro 6 levels, efficiencies approaching 50 per cent full load, and small efficiency penalties operating part load. The lean-burn direct-injection (DI) jet ignition ICE uses a fuel injection and mixture ignition system consisting of one main-chamber DI fuel injector and one small jet ignition pre-chamber per engine cylinder. The jet ignition pre-chamber is connected to the main chamber through calibrated orifices and accommodates a second DI fuel injector. In the spark plug version, the jet ignition pre-chamber includes a spark plug which ignites the slightly rich pre-chamber mixture which then, in turn, bulk ignites the ultra-lean stratified main-chamber mixture through the multiple jets of hot reacting gases entering the in-cylinder volume. The paper uses coupled computer-aided engineering and computational fluid dynamics (CFD) simulations to provide better details of the operation of the jet ignition pre-chamber analysed so far with downstream experiments or stand-alone CFD simulations, thus resulting in a better understanding of the complex interactions between chemistry and turbulence that govern the pre-chamber flow and combustion.
- Content Type Journal Article
- DOI 10.1243/09544070JAUTO1465
- Authors
- A Boretti, School of Science and Engineering, University of Ballarat, Ballarat, Victoria, Australia
- R Paudel, School of Science and Engineering, University of Ballarat, Ballarat, Victoria, Australia
- A Tempia, Robert Bosch (Australia) Pty Ltd, Clayton, Victoria, Australia
Date: Tue, 06 Jul 2010 18:39:29 GMT
This paper focuses on the engagement process of face-dog clutches on heavy duty automated mechanical transmissions (AMTs) considering special engagement conditions caused by the actuation of an electro-pneumatic transmission brake. A dynamic model of the transmission brake – single face-dog clutch system is developed and the engagement probability map characterizing the engagement capability of face-dog clutches under different engagement conditions is determined through numerical simulations for different gears of a given AMT. A region of engagement conditions is recognized where the engagement of the face-dog clutch is not ensured. Parameters influencing that region are highlighted. Optimal engagement conditions providing major gearshift comfort are given for the cases of stopped and moving vehicles. Simulation results are partly validated through statistical evaluation of measurement data obtained from a series of measurements performed on a gearbox test bench.
- Content Type Journal Article
- DOI 10.1243/09544070JAUTO1435
- Authors
- G Bóka, Department of Vehicle Part and Drives, Budapest University of Technology and Economics, Budapest, Hungary
- L Lovas, Department of Vehicle Part and Drives, Budapest University of Technology and Economics, Budapest, Hungary
- J Márialigeti, Department of Vehicle Part and Drives, Budapest University of Technology and Economics, Budapest, Hungary
- B Trencséni, Department of Vehicle Part and Drives, Budapest University of Technology and Economics, Budapest, Hungary
Date: Tue, 06 Jul 2010 18:39:29 GMT
In this paper, experiments were carried out on a direct-injection diesel engine using a common-rail system, in order to study the effects of multi-injection modes on the combustion characteristics and pollutant emissions. A soot model was proposed for the post-injection mode, namely the Hiroyasu–Kodota averaged-reaction-rate soot model, which took into account both the chemical kinetics reaction and the turbulent mixing motion of the spray jet. Through integrating the revised soot model into a computational fluid dynamics (CFD) code, the combustion process and pollutants formation of the tested engine were simulated. The in-cylinder gas pressure and combustion heat release rate showed satisfactory agreement with measurements. The experimental data demonstrated that the pilot-injection mode was one of the most effective measures for reducing combustion noise. Meanwhile an optimum split-injection mode consisting of an appropriate pilot-injection fuel quantity combined with an optimal pilot-injection–main-injection interval could be achieved to decrease the nitrogen oxide (NOx) emission while not causing the particulate matter (PM) emission to deteriorate very much. Two innovative concepts of an active thermo-atmosphere and a passive inert atmosphere were presented from numerical simulation to discuss the effect of the pilot-injection mode on the combustion behaviour of the main injection. Regarding the post-injection mode, its prominent advantage was to decrease extremely the PM emission without an NOx emission penalty. Furthermore, by CFD modelling of the soot formation process, it can be observed that the turbulent mixing motion caused by the post-injection spray played a vital role in the soot oxidization process.
- Content Type Journal Article
- DOI 10.1243/09544070JAUTO1434
- Authors
- X-Y Shi, College of Automotive Engineering, Tongji University, Shanghai, People's Republic of China
- X-Q Qiao, School of Mechanical and Power Engineering, Shanghai Jiaotong University, Shanghai, People's Republic of China
- J-M Ni, College of Automotive Engineering, Tongji University, Shanghai, People's Republic of China
- Y-Y Zheng, Department of Civil Engineering, Shandong Jiaotong University, Jinan, People's Republic of China
- N-Y Ye, College of Automotive Engineering, Tongji University, Shanghai, People's Republic of China
Date: Tue, 06 Jul 2010 18:39:28 GMT
This paper extends recent research on vehicles with hydraulically interconnected suspension (HIS) systems. Such suspension schemes have received considerable attention in the research community over the last few years. This is due, in part, to their reported ability to provide stiffness and damping rates dependent on the suspension mode of operation (i.e. the bounce, roll, pitch, or articulation of the unsprung masses relative to the sprung mass), rather than relying on the stiffness and damping characteristics of the single wheel stations.
In this paper, the optimization of such a system is considered. Use is made of a previously derived four-degree-of-freedom model of a roll-plane half-car fitted with a typical antiroll HIS system. Objective functions are then developed, based on the desire to improve ride comfort and to minimize suspension working space and tyre normal force fluctuations. With this formulation, a large number of optimal solutions are found and presented graphically, and the performance limitations and trade-offs between the desired objectives are illustrated. To contextualize these results, a similar optimization process is applied to a half-car with a conventional independent suspension. Four optimal parameter combinations are then selected as base points for further examination of the HIS vehicle. This is done by way of a basic sensitivity analysis, based on the local method, which involves single-parameter perturbations about a base point.
The objective of the paper is to outline the dynamic performance, trade-offs, and limitations of a HIS-equipped vehicle, and to identify the system's most important parameters.
- Content Type Journal Article
- DOI 10.1243/09544070JAUTO1422
- Authors
- W A Smith, Mechatronics and Intelligent Systems, Faculty of Engineering, University of Technology, P.O. Box 123, Broadway, Sydney, NSW, 2007, Australia
- N Zhang, Mechatronics and Intelligent Systems, Faculty of Engineering, University of Technology, P.O. Box 123, Broadway, Sydney, NSW, 2007, Australia
Date: Tue, 06 Jul 2010 18:39:28 GMT
The main purpose of this article is to optimize the stiffness and damping parameters of suspension systems to improve the ride comfort of a coach by using the pseudo excitation method (PEM) and the method of moving asymptotes (MMA). The finite element model of the coach under investigation has 1778 degrees of freedom. The surface roughness of the highway is regarded as a spatial stationary random process, which is accurately transformed into the superposition of a series of deterministic pseudo-harmonic surface unevennesses by using PEM. By doing so, the proposed method considerably simplifies the solution of the vibration equations, the derivation of sensitivities of various random responses, and the execution of the optimization process. MMA is applied to solve the ride comfort optimization problem. The proposed method is well justified by the numerical example.
- Content Type Journal Article
- DOI 10.1243/09544070JAUTO1417
- Authors
- W Sun, Department of Engineering Mechanics, State Key Laboratory of Structural Analysis and Industrial Equipment, Dalian University of Technology, Dalian, People's Republic of China
- W-T Xu, Department of Engineering Mechanics, State Key Laboratory of Structural Analysis and Industrial Equipment, Dalian University of Technology, Dalian, People's Republic of China
- J-H Lin, Department of Engineering Mechanics, State Key Laboratory of Structural Analysis and Industrial Equipment, Dalian University of Technology, Dalian, People's Republic of China
- D Kennedy, Cardiff School of Engineering, Cardiff University, Cardiff, UK
- F W Williams, Cardiff School of Engineering, Cardiff University, Cardiff, UK
Date: Tue, 06 Jul 2010 18:39:27 GMT
In this paper, a new rate-based phenomenological model of piezoelectric actuators for real-time applications is developed. This compact theoretical approach employs the Arrhenius equation for chemical reaction kinetics in order to describe the non-linear effect of domain switching. It needs only nine model parameters to account for the complete non-linearity of a piezoelectric actuator as well as the dependence of its non-linear effect on the electric field, the mechanical stress, and the temperature. This general validity for a wide range of operation conditions, which is based on a simplified description of the real behaviour, is the optimum prerequisite for a technically inexpensive control loop strategy for fast piezoelectric actuators as they are employed in state-of-the-art gasoline and diesel injectors for combustion engines. Moreover, other interfering physical effects, such as ageing, which may cause an injector's dosing function to deteriorate severely can be tackled by making use of this approach in electronic control units. All this is possible because the extremely compact theoretical formulation with a compact set of parameters does not need access to complex characteristic diagrams so that the most essential requirements of an automotive control unit such as a minimum computation time and a modest requirement of storage space can be fulfilled.
- Content Type Journal Article
- DOI 10.1243/09544070JAUTO1413
- Authors
- M Hoege, Siemens AG, Munich, Germany
- R Mock, Siemens AG, Munich, Germany
- E Magori, Siemens AG, Munich, Germany
Date: Tue, 06 Jul 2010 18:39:27 GMT
This paper describes a driving control algorithm based on a skid steering for a robotic vehicle with articulated suspension (RVAS). The RVAS is a kind of unmanned ground vehicle based on a skid steering using an independent in-wheel drive at each wheel. The driving control algorithm consists of four parts: a speed controller for following a desired speed, a lateral motion controller that computes a yaw moment input to track a desired yaw rate or a desired trajectory according to the control mode, a longitudinal tyre force distribution algorithm that determines an optimal desired longitudinal tyre force, and a wheel torque controller that determines a wheel torque command at each wheel in order to keep the slip ratio at each wheel below a limit value as well as to track the desired tyre force. Longitudinal and vertical tyre force estimators are required for the optimal tyre force distribution and wheel slip control. A dynamic model of the RVAS for simulation study is developed and validated using the vehicle test data. Simulation and vehicle tests are conducted in order to evaluate the proposed driving controller. It is found from simulation and vehicle test results that the proposed driving controller provides a satisfactory motion control performance according to the control mode.
- Content Type Journal Article
- DOI 10.1243/09544070JAUTO1405
- Authors
- J Kang, School of Mechanical and Aerospace Engineering, Seoul National University, Seoul, Republic of Korea
- W Kim, Program in Automotive Engineering, Seoul National University, Seoul, Republic of Korea
- J Lee, Samsung Techwin, Gyeongsang-do, Republic of Korea
- K Yi, School of Mechanical and Aerospace Engineering, Seoul National University, Seoul, Republic of Korea
Date: Tue, 06 Jul 2010 18:39:26 GMT
A centrifugal turbo blower is one of the important parts used for generating electric power in a fuel cell electric vehicle (FCEV). The impeller blades of the centrifugal turbo blower must rotate at a high speed to generate electric power. The unbalance and asymmetry of the rotating parts, such as impeller blades, become causes of the heavy vibration of the centrifugal turbo blower. This vibration is transmitted to the chassis frame of the FCEV through vibration isolators and becomes one of major sources of the interior noise in the FCEV. Therefore, the vibration generated from a centrifugal turbo blower should be attenuated properly to reduce the interior noise. To achieve this effectively, quantification of the vibration energy flow through the isolators is necessary since it gives information on the quantification of the vibrational energy flow from the centrifugal turbo blower to the chassis frame. Information on the vibrational power flow at each vibration isolator identifies the vibration transmission path. In this paper, a simple equation is derived to calculate the vibration power flow through each vibration isolator. With this equation, the vibrational power flow through each isolator is numerically simulated. In this simulation, the vibration generated from the centrifugal turbo blower is predicted using the multi-body dynamic analysis of a three-dimensional model of the centrifugal turbo blower based on computer-aided engineering. These simulated results are confirmed by measurement of the vibration power flow generated from the centrifugal turbo blower in a laboratory.
- Content Type Journal Article
- DOI 10.1243/09544070JAUTO1309
- Authors
- Y S Kim, Department of Mechanical Engineering, Inha University, Inchon, Republic of Korea
- E Y Kim, Department of Mechanical Engineering, Inha University, Inchon, Republic of Korea
- S-K Lee, Department of Mechanical Engineering, Inha University, Inchon, Republic of Korea
Date: Tue, 06 Jul 2010 18:39:24 GMT
An electronic wedge brake (EWB) uses the wedge principle to provide a self-reinforcement mechanism, resulting in reduced current to the actuation motor. However, this mechanism can lead to an unstable open-loop system. In this study, an upper-wedge moving-type EWB is developed and a control algorithm is proposed to follow the target clamping force and to prevent jamming of the EWB system using the push–pull control of the actuator. The performance of the EWB is evaluated using a dynamometer and a simulator. Based on testing and simulation, the clamping force and braking time of the proposed EWB are shown to be satisfactory with respect to the required braking deceleration.
- Content Type Journal Article
- DOI 10.1243/09544070JAUTO1268
- Authors
- C-H Jo, School of Mechanical Engineering, Sungkyunkwan University, Suwon, Republic of Korea
- S-M Lee, School of Mechanical Engineering, Sungkyunkwan University, Suwon, Republic of Korea
- H-L Song, Computer Applied Mechanical Engineering, Ansan College of Technology, Ansan, Republic of Korea
- Y-S Cho, Daemyung Engineering Company, Kumsu-myeon, Sancheong-gun, Republic of Korea
- I Kim, Vehicle System Development Team, Hyundai-Kia R&D Center, Jangduk-dong, Hwasung-si, Republic of Korea
- D-Y Hyun, Vehicle System Development Team, Hyundai-Kia R&D Center, Jangduk-dong, Hwasung-si, Republic of Korea
- H-S Kim, School of Mechanical Engineering, Sungkyunkwan University, Suwon, Republic of Korea
Date: Mon, 07 Jun 2010 21:00:43 GMT
An extensive programme of work has been undertaken to assess the potential benefits of modulating the properties of both the engine and the transmission lubricating oils to achieve lower fuel consumption. The performance of the engine lubricants was evaluated on a production diesel engine on a transient test bed. The main engine lubricating-oil viscometric properties investigated were the cold cranking shear, the kinematic viscosity at 100 °C, and the high-temperature high-shear value. Up to 3.5 per cent fuel economy improvement was observed over the New European Drive Cycle (NEDC), relative to current production lubricants. A model relating the fuel consumption to the oil properties was developed and verified using an experimental programme conducted on a chassis dynamometer.
In a related study, the effects of changes in the transmission lubricant properties were evaluated using a standard five-speed manual transmission fitted to a light-goods vehicle and tested on a chassis dynamometer. The lubricant was heated using an external energy source to simulate the effect of a more rapid warm-up; this reduced the viscosity of the lubricant and a fuel consumption improvement of 0.7 per cent was demonstrated over the NEDC from a 25 °C start. In addition, a lower-viscosity lubricant blend was evaluated, which delivered a 1 per cent improvement in the fuel economy over the standard blend from a cold start, and a further 0.4 per cent improvement if heated.
- Content Type Journal Article
- DOI 10.1243/09544070JAUTO1534
- Authors
- J G Hawley, Department of Mechanical Engineering, University of Bath, Bath, Avon, UK
- C D Bannister, Department of Mechanical Engineering, University of Bath, Bath, Avon, UK
- C J Brace, Department of Mechanical Engineering, University of Bath, Bath, Avon, UK
- S Akehurst, Department of Mechanical Engineering, University of Bath, Bath, Avon, UK
- I Pegg, European P/T Research & Advanced, The Ford Motor Company Limited, Basildon, UK
- M R Avery, Global Lubricants Technology, BP plc, Reading, UK
Date: Mon, 07 Jun 2010 21:00:38 GMT
In the present study, the effects of the injection timing and the spark timing on the combustion characteristics and particle emission were investigated. The particulate number concentration and size distribution were measured using the electrical low-pressure impactor. The combustion parameters were calculated from the cylinder pressure data. The results indicate that the combustion versus the injection timing is primarily dependent on the mixing quality of the air–fuel mixture. The particulate number concentration increases as the fuel injection is advanced but the particle size distribution is not affected significantly with different injection timings. This is probably related to the in-cylinder combustion. The initial combustion duration increases as the spark timing is advanced and the fastest rapid combustion duration is obtained at the maximum brake torque spark timing. As the fuel injection timing and spark timing are advanced, the particle number levels are increased but the particle size distribution shows few variations. Most of the particulates are in the nanoparticle size range. The amounts of nitrogen oxide and hydrocarbon emissions increase with advanced fuel injection timing and spark timing, and the carbon monoxide concentration experiences small variations under all operation conditions.
- Content Type Journal Article
- DOI 10.1243/09544070JAUTO1532
- Authors
- Y-F Liu, State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, Xi'an, People's Republic of China
- B Liu, State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, Xi'an, People's Republic of China
- L Liu, State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, Xi'an, People's Republic of China
- K Zeng, State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, Xi'an, People's Republic of China
- Z-H Huang, State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, Xi'an, People's Republic of China
Date: Mon, 07 Jun 2010 21:00:30 GMT
Owing to their low carbon dioxide emissions and fuel consumptions, diesel engines have gained a significant market share of passenger cars in Europe. However, gasoline engines are exclusively used to power passenger cars in the People's Republic of China and many other countries. The introduction of diesel engines to the passenger car market in many countries is unlikely to take place in the near future because of the limited diesel fuel supply, higher cost of diesel cars, and public perception of diesel vehicles. Therefore, development of high-efficiency gasoline engines is of particular importance. As part of a State Key Project of the National Basic Research Program (the 973 Program), the present authors have carried out systematic research and development of a high-efficiency gasoline engine. The engine was equipped in production with devices for mechanically variable valve lift and timing and was operated with controlled autoignition (CAI) (homogeneous charge compression ignition) combustion under part-load conditions and spark-assisted combustion between the transitional region of CAI and the normal spark ignition (SI) combustion. This paper will describe the use of devices for variable valve lift and timing in a single-cylinder engine and their control. The engine performance and emission results in the CAI operational region are presented. The ability of the engine to achieve rapid and smooth transition between CAI and SI will be illustrated. A brief discussion of the implication of the results on the calculated driving-cycle fuel consumption will be given at the end. Finally, the plan for future development of a multi-cylinder engine of variable valve actuation will be given.
- Content Type Journal Article
- DOI 10.1243/09544070JAUTO1436
- Authors
- Y Zhang, State Key Laboratory of Engines, Tianjin University, Tianjin, People's Republic of China
- H Xie, State Key Laboratory of Engines, Tianjin University, Tianjin, People's Republic of China
- H Zhao, State Key Laboratory of Engines, Tianjin University, Tianjin, People's Republic of China
- B-Q He, State Key Laboratory of Engines, Tianjin University, Tianjin, People's Republic of China
Date: Mon, 07 Jun 2010 21:00:26 GMT
The flow-induced deformation of a membrane in a flow is studied using experimental and computational approaches in a configuration that represents the effect of the aerodynamic load on a convertible car roof. The computational method couples a commercial computational fluid dynamics code with an in-house structural code to predict membrane deformation. A converged statically deformed state, within 1 per cent difference in the displacement variable, is reached after three iterations between the fluid and structural codes. The predictions of membrane deformation are shown to agree well with the experimental results. The key outcome is the demonstration of methodology that will be useful in the engineering design of convertible car roofs.
- Content Type Journal Article
- DOI 10.1243/09544070JAUTO1408
- Authors
- J J Knight, School of Engineering and Technology, University of Hertfordshire, Hertfordshire, UK
- A D Lucey, Fluid Dynamics Research Group, Curtin University, Perth, Australia
- C T Shaw, Topajka Shaw Consulting Limited, Te Anau, New Zealand