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Technical Paper

CAD of engine dynamic test bed based on hybrid simulation

2000-06-12
2000-05-0348
The hybrid simulation method is adopted to develop engine dynamic test bed based on eddy-current dynamometer. The hybrid simulation scheme of engine dynamic test bed is designed. The principle is discussed. Finally, the CAD method is used to design main parameters of engine dynamic test bed based on simulation ECE15 and US LA4-CH Driving Schedules by Shanghai Santana 2000 car. The results are compared to the actual test results on the chassis dynamometer. The hybrid simulation method is proved to be an efficient way by simulation and comparison.
Journal Article

Closed Loop Control Algorithm of Fuel Cell Output Power for a City Bus

2013-04-08
2013-01-0479
This paper studies a control algorithm for fuel cell/battery city buses. The output power of the fuel cell is controlled by a D.C. converter, and the output ports of the converter and the battery are connected in parallel to supply power for the electric motor. One way to prolong service life is to have the fuel cell system to deliver a steady-state power. However, because of fluctuations in the bus voltage and uncertainness in the D.C. converter, the output power of the fuel cell system changes drastically. A closed-loop control algorithm is necessary to eliminate the errors between the output and target power of the fuel cell system. The algorithm is composed of two parts, the feed forward one and the feedback one. Influences of the bus voltage and D.C. efficiency are compensated automatically in the feedback algorithm by using a PI algorithm. The stability and robustness of the algorithm is analyzed.
Technical Paper

Lean Oxygen Gum Simulation Test for Gasoline Detergency and its Correlation with M111 Engine Test

2010-10-25
2010-01-2134
Gasoline detergency is related to deposits at various parts of the engine and therefore has impact on vehicle driveability and emission properties. The widely used engine tests such as CEC F-20 M111 and ASTM D6201 Ford 2.3L tests take tens of hours and thus are very expensive and time consuming to carry out. A new simulation test for gasoline detergency on intake valve cleanliness using lean-oxygen gum method was developed and the correlation of test results with M111 engine test was studied. Gasoline samples with different detergency levels were tested with both the lean-oxygen gum method and the M111 engine test. Test results of 24 gasoline samples show satisfactory correlation between the lean-oxygen gum method and the M111 engine test (R₂=0.7258).
Technical Paper

An Experimental Study Using Spark-Assisted Stratified Compression Ignition (SSCI) Hybrid Combustion Mode for Engine Particle Number (PN) Reduction in a High Compression Ratio Gasoline Engine

2016-04-05
2016-01-0758
Particle Number (PN) have already been a big issue for developing high efficiency internal combustion engines (ICEs). In this study, controlled spark-assisted stratified compression ignition (SSCI) with moderate end-gas auto-ignition was used for reducing PN in a high compression ratio gasoline direct injection (GDI) engine. Under wide open throttle (WOT) and Maximum Brake Torque timing (MBT) condition, high external cooled exhaust gas recirculation (EGR) was filled in the cylinder, while two-stage direct injection was used to form desired stoichiometric but stratified mixture. SSCI combustion mode exhibits two-stage heat release, where the first stage is associated with flame propagation induced by spark ignition and the second stage is the result of moderate end-gas auto-ignition without pressure oscillation at the middle or late stage of the combustion process.
Technical Paper

Substructure Modal Composition and Sensitivity Analysis based on Closed-Loop Coupling Model without Coupling Spring

2016-04-05
2016-01-1309
In this paper, analysis methods for brake squeal including substructure modal composition analysis and substructure modal parameters sensitivity analysis are presented. These methods are based on a new closed-loop coupling disc brake model, where the coupled nodal pairs in each coupling interface are connected tightly. This assumption is different from other existing models in literatures, where the interface nodes are coupled through assumed springs. Based on this new model, two analysis methods are derived: Substructure modal composition analysis indicates the contribution of modes of each substructure to the noise mode; Substructure modal parameters sensitivity analysis indicates the sensitivity of the real part of system’s eigenvalue to component’s modal frequency and shape. Finally, the presented analysis methods are applied to analyse a high frequency squeal problem of a squealing disc brake.
Technical Paper

A Quasi-Dimensional Combustion Model for SI Engines Fuelled by Hydrogen Enriched Compressed Natural Gas

2008-06-23
2008-01-1633
HCNG is short for hydrogen enriched natural gas. Compared to traditional gasoline, diesel or even natural gas engines HCNG fuelled engines have several advantages on environment protection and energy security and in order to make full extent of the new fuel, several modifications have to be made in the corresponding engine and the control strategy. So there is a need to develop a predictive model to simulate the engine's performance without really running the engine, which could speed up the development of HCNG engines. This paper dose such a job. At first the paper presents the fundamentals of the quasi-dimensional model. The equations of the two-zone thermodynamic model and turbulent entrainment combustion model are both introduced. The methods of calculating the related parameters such as theoretical adiabatic flame temperature, laminar burning velocity of HCNG mixture under various hydrogen blending ratios are also given.
Technical Paper

Development and Validation of an On-line Hydrogen-Natural Gas Mixing System for Internal Combustion Engine Testing

2008-06-23
2008-01-1580
Hydrogen enriched compressed natural gas (HCNG) is thought to be a potential alternative to common hydrocarbon fuels for SI engine applications. Experimental researches focusing on how to use this kind of fuel to its full extent have been conducted for over ten years and are still on their way. From a review of these researches it is found that one of the biggest obstacles of efficiently and economically conducting such experiments is how to mix desired amount of hydrogen with natural gas. Most of the previous experiments use pre-bottled hydrogen/ NG mixtures (by mixing and storing desired amount of hydrogen and NG in high pressure steel cylinders before the tests) which are quite costly and unsafe, due to high pressure operation. More importantly, the blending ratio cannot be varied by that approach. By comparison, this paper presents an on-line hydrogen-natural gas mixing system through which the hydrogen/ NG blending ratio can be easily varied during the tests.
Technical Paper

Experimental and theoretical study on the swirl exhaust system for diesel engines

2000-06-12
2000-05-0162
On the basis of modular pulse converter (MPC) exhaust system the authors present a new swirl exhaust system. Structural parameters on the swirl exhaust system and MPC system for N8160ZC diesel engine were calculated by a mathematical optimum method, and the two systems were tested under the same engine operation for comparison. Experimental results show that the swirl exhaust system has a better engine performance under most of the operating conditions than MPC system, but worse under the low-speed and part-load conditions. In order to understand the mechanism of this swirl exhaust system well, a three-dimensional particle dynamic analyzer (3D-PDA) was utilized to measure the steady turbulent airflow in a swirl three-branched model. The computational fluid dynamics (CFD) code KIVA was modified to simulate the flows. Computational results are in good agreement with measuring ones and reveal the swirl flow behavior in the junction.
Technical Paper

Develop of active suspension and experimental study of control strategy based on output feedback and frequency shaping

2000-06-12
2000-05-0179
In this paper, a 2-DOF experimental equipment of active suspension is developed. This system is hydro-pneumatic type and is controlled through oil flow. A control strategy based on output feedback and frequency shaping is proposed and realized on this model. Output feedback can reduce the number of system states that should be measured and thus simplify the complexity and improve the reliability of the system. Because of the different human sensitivity to different frequency ranges of vibration, it is necessary to pay effort on the suppression of vibration according to human sensitivity. Frequency shaping technology is thus applied on performance index to improve the ride quality. Several types of measurement versions are investigated and optimized. Simulation results indicate that using sprung mass velocity and suspension deflection, the system performance can approach the full-state feedback system performance.
Technical Paper

Study on Brake Squeal by Feed-In Energy Analysis

2001-03-05
2001-01-0950
Brake squeal noise is studied in this paper by feed-in energy analysis. Based on the closed-loop coupling brake model, the computation method of feed-in energy is derived for the system squeal mode. The amount of feed-in energy can indicate the degree of squeal tendency of the brake system. Feed-in energy analysis can clearly reveal the influence of some structural parameters on brake noise, such as coefficient of friction, the geometric shape and stiffness of pads, and key substructure modal shape. It also can help to analyze the structure modification to eliminate brake squeal.
Technical Paper

Coordinated Control of EGR and VNT in Turbocharged Diesel Engine Based on Intake Air Mass Observer

2002-03-04
2002-01-1292
Coordinated EGR-VNT control based on the intake air mass observer is presented in this paper to deal with the transient AFR control of turbocharged diesel engine. The air mass model embedded in the observer is a Takagi-Sugeno fuzzy neural network trained with transient simulation results. It can predict the charged fresh air mass entering the cylinder. In a high load region, when EGR is not effective, the coordinated EGR-VNT control will also bring benefits to the transient air-fuel-ratio control. The simulation results of TDI engine model verify that the transient control strategy will allow a better control of the intake air mass, and thus improve air-fuel-ratio control and reduce NOx emission in transients.
Technical Paper

Design Concepts of the Four-Wheel-Independent Electro-Hydraulic Braking System

2014-09-28
2014-01-2537
The four-wheel-independent Electro-hydraulic Braking system (4WI EHB) is a wet type Brake-by-Wire system for passenger vehicle and is suitable for electric vehicle (EV) and hybrid electric vehicle (HEV) to cooperate with regenerative braking. This paper gives a review on the design concepts of the 4WI EHB from the following three aspects. 1. Hydraulic architectures. 2. Design concepts of the brake actuator. 3. Installation of the components on the vehicle. Simulations and experiments are carried out to further explore the performance of hydraulic backup and implicit hardware redundancy (IHR). A method to integrate the IHR with hydraulic backup without increasing the total amount of valves is proposed, making the IHR cost and weight competitive. By reviewing various design concepts and analyzing their advantages and drawbacks, a cost and weight competitive design concept of the 4WI EHB with good fail-safe and fault-tolerant performance is proposed.
Technical Paper

Experimental Research and Optimal Design of an Automotive Magneto-Rheological Brake System

2014-09-28
2014-01-2534
The paper is focused on the research of the automotive magneto-rheological brake system whose braking force comes from the shear stress of magneto-rheological fluid under the condition of magnetic field. The MRF brake is designed for an electric passenger car to replace a conventional hydraulic disc-type brake. The braking torque of this system can be linearly adjusted by the current in just a few milliseconds with proper materials. Therefore this system has a quick response and precise control performance with a low hysteresis. Nowadays, most of the related research of MRF is about the construction of the prototype and the realization of the brake force. Main limitation of MRF brake lies in the braking torque cannot meet the actual needs and the power consumption may be too much if it is not well designed. The prototype introduced in the SAE Brake Colloquium-31nd Annual has been manufactured and assembled critically.
Technical Paper

Design, Modeling and Simulation of a New Compact Electro-Hydraulic Brake System

2014-09-28
2014-01-2535
With the advantages of free from engine vacuum, wheel cylinder pressure decoupled from the brake pedal and can be regulated individually and precisely, the brake-by-wire system has a huge application potential in vehicles, especially in electric vehicles (EV) and hybrid electric vehicles (HEV). Electro-hydraulic Brake system is the first approach towards brake-by-wire technology. This paper proposed a new compact EHB, aiming at decreasing the size, volume and cost without compromise of performance. The main components of the proposed EHB are pedal simulator, motor pump, accumulator and eight solenoid valves. An authentic model of the EHB and other key components of the brake system were established based on the test data from the test bench. A control algorithm using Round-Robin scheduling was presented to regulate the fluid pressure. Some parameters of the components were discussed to research their effects on system performance.
Technical Paper

A Turbulence and Cavitation Induced Breakup Model for Fuel Spray Modeling

2014-10-13
2014-01-2737
Fuel spray atomization process is known to play a key role in affecting mixture formation, combustion efficiency and soot emissions in direct injection engines. The fuel spray Computational Fluid Dynamics (CFD) modeling technology can be an effective means to study and predict spray characteristics such as penetration, droplet size and droplet velocity, and as a consequence, to drastically reduce experimental work during the engine development process. For this reason, an accurate numerical simulation of the spray evolution process is imperative. Different approaches and various models based on aerodynamically induced breakup mechanism have been implemented to simulate spray atomization process in earlier studies, and the effects of turbulence and cavitation from the injector nozzle is recently being concerned increasingly by engine researchers. In this study, an enhanced turbulence and cavitation induced primary breakup model combining aerodynamic breakup mechanism is developed.
Technical Paper

The Comparative Study of Gasoline and n-butanol on Spray Characteristics

2014-10-13
2014-01-2754
n-butanol has been recognized as a promising alternative fuel for gasoline and may potentially overcome the drawbacks of methanol and ethanol, e.g. higher energy density. In this paper, the spray characteristics of gasoline and n-butanol have been investigated using a high pressure direct injection injector. High speed imaging and Phase Doppler Particle Analyzer (PDPA) techniques were used to study the spray penetration and the droplet atomization process. The tests were carried out in a high pressure constant volume vessel over a range of injection pressure from 60 to 150 bar and ambient pressure from 1 to 5 bar. The results show that gasoline has a longer penetration length than that of n-butanol in most test conditions due to the relatively small density and viscosity of gasoline; n-butanol has larger SMD due to its higher viscosity. The increase in ambient pressure leads to the reduction in SMD by 42% for gasoline and by 37% for n-butanol.
Technical Paper

The Study of Operating Efficiency Enhancement of Traction Motor with the Application of a Two-Speed Transmission in an Electric Bus

2014-10-13
2014-01-2891
This paper discusses whether it is possible to improve the motor efficiency by a two-speed transmission in an electric bus, and if so, to what extent. Based on the China Bus Urban Cycle, an 8-meter electric bus was studied via simulation in Matlab/Simulink. The comparison of motor efficiency between two different configurations was made: direct drive and drive through a two-speed transmission. In the first part of the simulation, the speed ratios of the two-speed transmission were chosen as 1.5 and 3.5. The motor efficiency was improved by 1.22% for driving and 1.66% for generation. To find out the maximum improvement and corresponding optimal speed ratio combination, scanning experiment of the lower ratio and upper ratio was conducted in the second part. As much as 1.66% improvement of driving efficiency and 2.20% of regenerating efficiency was achieved.
Technical Paper

Urea Decomposition at Low Temperature in SCR Systems for Diesel Engines

2014-10-13
2014-01-2808
Selective catalytic reduction (SCR) has been demonstrated as one of the most promising technologies to reduce NOx emissions from heavy-duty diesel engines. To meet the Euro VI regulations, the SCR system should achieve high NOx reduction efficiency even at low temperature. In the SCR system, NH3 is usually supplied by the injection of urea water solution (UWS), therefore it is important to improve the evaporation and decomposition efficiency of UWS at low temperature and minimize urea deposits. In this study, the UWS spray, urea decomposition, and the UWS impingement on pipe wall at low temperature were investigated based on an engine test bench and computational fluid dynamics (CFD) code. The decomposition of urea and deposits was analyzed using thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC) and fourier transform infrared spectroscopy (FTIR).
Technical Paper

Prototype of Distributed Electro-Hydraulic Braking System and its Fail-Safe Control Strategy

2013-09-30
2013-01-2066
Prototype of a brake-by-wire (BBW) system named Distributed Electro-hydraulic Braking System (DEHB) has been developed. As a BBW system, DEHB is suitable to be used in electric vehicles (EV) and hybrid electric vehicles (HEV). Comparing to the ‘dry’ type distributed BBW systems such as Electro-mechanical Braking System (EMB) or Electric Wedge Brake (EWB), the ‘wet’ feature of DEHB brings benefits to system cost, installation, performance and reliability. In this paper, prototype of the DEHB was described. Based on its ‘wet’ feature, a new fail-safe control for DEHB was proposed. Two types of DEHB architectures that can perform the proposed fail-safe control were described. Superiority of the proposed fail-safe control and architectures for DEHB were examined and verified through simulations and HIL experiments, which helps DEHB to reach a high level of safety and reliability with reduced cost on electro/electronic redundancy.
Technical Paper

A Novel Direct Yaw Moment Control System for Autonomous Vehicle

2018-08-07
2018-01-1594
Although autonomous driving technology has become an emerging research focus, safety is still the most crucial concern when autonomous vehicles leave research laboratory and enter public traffic. Direct yaw moment control (DYC), which differentially brakes the wheels to produce a yaw moment, is an important system to ensure the driving stability of vehicle under extreme conditions. Traditional DYC system must need to take into account driver’s intention and vehicle dynamics. However, for autonomous vehicle, no human is involved in driving process, and enforcing traditional DYC system may conflict with the demands of the desired path. Therefore, in this paper, a novel DYC system for autonomous vehicle is proposed to simultaneously suppress lateral path tracking deviation while maintaining autonomous vehicle stability at or close to the driving limits. In the hardware aspect, an integrated-electro-hydraulic brake (IEHB) actuator scheme is adopted.
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