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Technical Paper

Fatigue Design and Analysis of the Vehicle Exhaust System's Hanger

2013-10-14
2013-01-2609
The weight of an exhaust system on a modern vehicle is increasing because of all kinds of reasons, like engine power's increasing, more catalysts for emission control and more NVH (Noise, Vibration and Harshness) performance requirements. After the engine starting, the exhaust system was not only bearing a cyclical load from the engine, which mainly causing the vibration of the exhaust system, but also the loads from the road, which was transferred through the wheels, the suspension system and the body. Because the exhaust system always worked in these bad conditions, its structural strength, durability and life-time were analyzed in the paper, by numerical simulation and physical correlation. By discretizing the exhaust system's CAD model, a finite element model was built. After restrict the finite element model as it in a real load condition, complete the structure stress analysis and Fatigue analysis of exhaust system's hanger with FEA analysis tools.
Technical Paper

Investigations on Mixture Formation during Start-UP Process of a Two-Stage Direct Injection Gasoline Engine for HEV Application

2013-10-14
2013-01-2657
A cycle-resolved test system was designed in a Two Stage Direct Injection (TSDI) Gasoline engine to simulate the engine quick start process in an Integrated Start and Generator (ISG) Hybrid Electric Vehicle (HEV) system. Based on the test system, measurement of the in cylinder HC concentrations near the spark plug under different engine coolant temperature and cranking speed conditions were conducted using a Fast Response Flame Ionization Detector (FFID) with Sampling Spark Plug (SSP) fits, then the in-cylinder equivalence ratio near the spark plug was estimated from the measured HC concentrations. In addition, the effects of the 1st injection timing, 2nd injection timing, and total equivalence ratio on the mixture formation near the spark plug were analyzed by means of experiments.
Technical Paper

Transient Characteristics of Cold Start Emissions from a Two-Stage Direct Injection Gasoline Engines Employing the Total Stoichiometric Ratio and Local Rich Mixture Start-up Strategy

2012-04-16
2012-01-1068
To improve the cold start performance and to reduce the misfire occurrence at cold start, the start-up strategy of total stoichiometric ratio combined with local rich mixture was applied in the study. The effect of injection strategy (the 1st injection timing, 2nd injection timing, 1st and 2nd fuel injection proportion and ignition timing) on the cold start HC emissions in the initial 10 cycles were investigated in a Two stage direct injection (TSDI) gasoline engine. The transient HC and NO emissions in the initial 10 cycles were analyzed, when the fuels are injected in the only 1st cycle and in the followed all cycles. The transient misfiring HC emissions were compared between the single and two-stage injection modes. In addition, the unburned HC (UBHC) emissions in the 1st cycle are compared among the TSDI engine, Gasoline direct injection (GDI) engine, Port fuel injection (PFI) engine and Liquefied petroleum gaseous (LPG) engine at the stoichiometric ratio.
Technical Paper

A Novel Closed Loop Control based on Ionization Current in Combustion Cycle at Cold Start in a GDI Engine

2012-04-16
2012-01-1339
As the invalidation of the oxygen sensor in the initial cycles at cold start, the engine can not operate based on the closed loop control based on oxygen sensor. And it may result in the misfire events and higher hydrocarbon (HC) emissions during this period. To solve this problem, a novel closed loop control based on ionization current in combustion cycle is proposed. The in-cylinder combustion quality is monitored by means of the ion current detection technique; meanwhile, if the misfire event is detected in the combustion cycle, the spark re-ignition is made in the current combustion cycle. In addition, to optimize the combustion and reduce HC emissions during cold start, the fuel injection quantity and ignition timing in the next cycle are adjusted based on the current ion current signal.
Technical Paper

On Chaos and Bifurcation in Nonlinear Driver-Vehicle System Probabilistic Dynamics

2012-04-16
2012-01-0522
The vehicle system is actually a strongly nonlinear system with stochastic parameters. In this paper, the nonlinearities of suspension, tire and seat are analyzed, and the nonlinear dynamics model of driver-vehicle system with 8 degrees of freedom (DOFs) is built. The bifurcation and chaotic motion of the deterministic system under Sinusoid excitations considering the time delay between the front and rear tires are studied. Then, the stochastic feature of the equivalent stiffness and damping coefficients of suspension, tire and seat are assumed to be the normal distribution, and the nonlinear model with random parameters is obtained. The nonlinear dynamics of stochastic nonlinear driver-vehicle system is analyzed and compared through numerical simulation.
Technical Paper

Spray Characteristics and Wall-impingement Process with Different Piston Tops for the Multi-hole Injector of DISI Gasoline Engines

2011-04-12
2011-01-1222
Spray characteristics and spray wall-impingement events are the key factors for the direct injection spark ignition (DISI) engines, affecting fuel/air mixture preparation and its combustion process. Thus, the spray characteristics of a multi-hole injector for DISI engines, such as spray tip penetration and spray cone angle were investigated in an optical chamber employing the high-speed shadow photography. Furthermore, the effects of the injection pressure, ambient pressure and piston top shape on the impinging spray development were studied in the optical chamber, when the impinging distance is 26.1 mm, corresponding to about 60 CAD ATDC. In addition, the SMD and wall film thickness of the spray impinging on the piston top were studied by means of CFD technique. The results showed that the ambient pressure had the greater effect on the changes of the spray penetration and spray cone angle than the injection pressure.
Technical Paper

Optimization of Control Strategy for Engine Start-stop in a Plug-in Series Hybrid Electric Vehicle

2010-10-25
2010-01-2214
Plug-in hybrid electric vehicles (PHEVs) provide significantly improvement in fuel economy over conventional vehicles as well as reductions in greenhouse gas and petroleum. Numerous recent reports regarding control strategy, power train configuration, driving pattern, all electric range (AER) and their effects on fuel consumption and electric energy consumption of PHEVs are reported. Meanwhile, the control strategy for engine start-stop and mileage between recharging events from the electricity grid also has an important influence on the petroleum displacement potential of PHEVs, but few reports are published. In this paper, a detailed simulation model is set up for a plug-in series hybrid electric vehicle (PSHEV) employing the AVL CRUISE. The model was employed to predict the AER of the baseline PSHEV using rule-based logical threshold switching control strategy.
Technical Paper

Power Matching and Control Strategy of Plug-in Series Hybrid Electric Car

2010-10-25
2010-01-2195
In this paper, based on the plug-in series hybrid electric vehicle development project, the vehicle technology solutions and the match of power system parameters were analyzed. The vehicle control strategies were identified and optimized according to plug-in hybrid vehicle features. The plug-in series hybrid, rule-based logic threshold switching control strategy, charge depleting (CD) mode and charge-sustaining (CS) mode are chosen according to the key factors, such as the environment, performance requirements, technical requirements and cost. And then the structure and model of vehicle control strategy were established to carry out vehicle energy management and power system control. The parameter selection, electric drive system matching, energy storage system design based on the requirement of vehicle performance, system architecture and control strategy are presented.
Technical Paper

Theoretical Modeling and FEM Analysis of the Thermo-mechanical Dynamics of Ventilated Disc Brakes

2010-04-12
2010-01-0075
Prediction and analysis of the thermo-mechanical coupling behavior in friction braking system is very important for the design and application of vehicle brakes, such as brake judder, brake squeal, brake wear, brake cracks, brake fade. This paper aims to establish a macro-structural model of the thermo-mechanical dynamics of the ventilated disc brake with asymmetrical outer and inner disc thickness, taking into account the friction-velocity curve of the disc pad couple acquired by testing. On the basis of finite elements analysis of the model, the predictions of the thermo-mechanical responses of the brake disc are presented, including disc transient temperature field and normal stress in radial, circular and axial directions, disc lateral deformation and disc thickness variation. Numerical predictions of the disc surface temperature and later distortion are compared with experimental measurements obtained by thermocouples and non-contact displacement sensors.
Technical Paper

Simulations of Key Design Parameters and Performance Optimization for a Free-piston Engine

2010-04-12
2010-01-1105
To develop a free-piston engine-alternator integrative power system for Hybrid Electric Vehicles, the key design parameters, such as reciprocating mass of the piston assembly, compression ratio, the ignition timing, the engine fuel consumption rate and power output, are studied based on the simulation. The results show that, the system simulation model of the free piston engine can predict the in-cylinder pressure vs. the piston's displacement being accurate enough as the test results from reported reference. The model can be employed to optimize the design parameters and to predict the fuel economy and power output. It provides the methods and bases for the free piston engine design and predicting the main performance parameters' values.
Technical Paper

Stratified Mixture Formation and Combustion Process for Wall-guided Stratified-charge DISI Engines with Different Piston Bowls by Simulation

2010-04-12
2010-01-0595
This paper presents the simulation of in-cylinder stratified mixture formation, spray motion, combustion and emissions in a four-stroke and four valves direct injection spark ignition (DISI) engine with a pent-roof combustion chamber by the computational fluid dynamics (CFD) code. The Extended Coherent Flame Combustion Model (ECFM), implemented in the AVL-Fire codes, was employed. The key parameters of spray characteristics related to computing settings, such as skew angle, cone angle and flow per pulse width with experimental measurements were compared. The numerical analysis is mainly focused on how the tumble flow ratio and geometry of piston bowls affect the motion of charge/spray in-cylinder, the formation of stratified mixture and the combustion and emissions (NO and CO₂) for the wall-guided stratified-charge spark-ignition DISI engine.
Technical Paper

Whole Field Bonded Steel Tensile Test Using Digital Image Correlation System

2010-04-12
2010-01-0960
Adhesive bonding has many applications in the automotive industry. The single-lapped bonded joint is the most typically used among various bonding types. This paper presents experimental research for determining the strain field of the single-lapped joint under tensile loading. The materials for the joint are epoxy-based structural adhesive and low-carbon electrolytic zinc steel plate. In the study, a DIC (digital image correlation) system was adopted to measure the strain distribution of the bonded joint during a tensile test. The bonded steel coupons in the tensile test were prepared according to the ASTM standard. During the measurement, images of the coupon joint were taken before and after the deformation process. Then the DIC system measured the strain of bonded joint by comparing two consecutive images. The measured data from the DIC was compared to data taken simultaneously from a traditional extensometer.
Technical Paper

Nucleation Mode Particle Emissions from a Diesel Engine with Biodiesel and Petroleum Diesel Fuels

2010-04-12
2010-01-0787
Effects of biodiesel fuel on nucleation mode particles were studied on a direct injection, high pressure common-rail diesel engine for passenger cars. Particle number and size distribution of the diesel engine were obtained using an Engine Exhaust Particle Sizer (EEPS). The base petroleum diesel, three different blend ratios of petroleum diesel/biodiesel (10%, 20% and 50% v/v biodiesel blend ratios), and the pure biodiesel fuel (obtained and converted from Jatropha seed in China) (B0, B10, B20, B50 and B100 fuels) were tested without engine modification. Experiments were performed on a series of engine operating conditions. The particle number size distribution of the engine shows unimodal or bimodal log-normal distribution. With the biodiesel blend ratios increasing, the number of nucleation mode particles increases at all test engine operating conditions and accumulation mode particles decreases at most engine operating conditions.
Technical Paper

Nonlinear Estimation of Vehicle Sideslip Angle Based on Adaptive Extended Kalman Filter

2010-04-12
2010-01-0117
An adaptive sideslip angle observer based on discrete extended Kalman filter (DEKF) is proposed in this paper and tire-road friction adaptation is also considered. The single track vehicle model with nonlinear tire characteristics is adopted. The tire parameters can be easily obtained through road test data without using special test rig. Afterwards, this model is discretized and the maximum value of tire-road friction is modeled as the third state variable. Through the measurement of vehicle lateral acceleration and yaw rate, the tire-road adhesion coefficient can be timely updated. Simulations with experimental data from road test and driving simulator have confirmed that DEKF has very high accuracy. The convergent speed of DEKF relies on the magnitude of lateral excitation.
Book

Road Vehicle Dynamics

2008-06-19
This book provides a detailed and well-rounded overview of the dynamics of road vehicle systems. Readers will come to understand how physical laws, human factor considerations, and design choices come together to affect a vehicle's ride, handling, braking, and acceleration. Following an introduction and general review of dynamics, topics include: analysis of dynamic systems; tire dynamics; ride dynamics; vehicle rollover analysis; handling dynamics; braking; acceleration; and total vehicle dynamics.
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