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This paper conducts simulation research on engine torque ripple suppression based on the engine torque observer by using a flywheel-ISG (integrated starter generator). Usually, engine torque can be suppressed by using a passive method such as by installing a flywheel or torsional damper. However, failure problems arise in hybrid system because of different mechanical characters of the engine and its co-axial ISG motor. On the prototype test bench, the flywheel of the engine has been removed and replaced by an ISG rotor, namely FISG (flywheel ISG). Besides, the crank and FISG rotor are directly connected, which means no dampers or clutches are installed. If the engine torque ripples can be suppressed by the same level as the flywheel and damper by FISG active torque compensation, the new system can be more compact and economical. Simulation efforts are made to verify its feasibility. Firstly, based on the experimental test bench, which is currently under construction.

Low temperature combustion (LTC) is an advanced combustion mode, which can achieve low emissions of NOx and PM simultaneously, and keep relatively high thermal efficiency at the same time. However, one of the major challenges for LTC is the cold condition. In cold conditions, stable compression ignition is hard to realize, while thermal efficiency and emissions deteriorate, especially for gasoline or fuel with high octane number. This study presents using pressure sensor glow plugs (PSG) to realize Glow plug assisted compression ignition (GA-CI) at cold conditions. Further, a glow plug control unit (GPCU) is developed, a closed-loop power feedback control algorithm is introduced based on GPCU. In the experiment, engine coolant temperature is swept. Experimental results show that GA-CI has earlier combustion phases, larger combustion duration and higher in-cylinder pressure. And misfire is avoided, cycle-to-cycle variations are greatly reduced.

Energy saving is becoming one of the most important issues for the next generation of commercial vehicles. The fuel consumption limits for commercial vehicles in China have stepped into the third stage, which is a great challenge for heavy duty commercial vehicles. Hybrid technology provides a promising method to solve this problem, of which the dual motor coaxial series parallel configuration is one of the best options. Compared with parallel configuration, the powertrain can not only operate in pure electric or parallel mode, but also can operate in series mode, which shows better flexibility. In this paper, regulations on test cycle, fuel consumption limits and calculation method of the third stage will be introduced in detail. Then, the quasi-static models of the coaxial series parallel powertrain with/without gearbox under C-WTVC (China worldwide transient vehicle cycle) are built. The control strategies are designed based on engine and motor performance.

Power-split configuration is highlighted as the most popular concept for full hybrid electric vehicles (HEV). However, the energy management and design of power-split heavy duty truck under Chinese driving conditions still need to be investigated. In this paper, the parametric design, a rule-based control strategy and an equivalent consumption minimization strategy (ECMS) for the power-split heavy duty truck are presented. Besides, the influence of a penalty factor also discussed under ECMS algorithm. Meanwhile, two different methods to search the engine operation point have been proposed and the reason of different economy performance is presented by using energy flow chart. And the simulation results show both fuel consumption can satisfy the second phase fuel consumption standard and the third phase fuel consumption standard which will be implemented in 2020, under C-WTVC (Chinese-World Transient Vehicle Cycle).

This paper conducts an investigation on the operating cycle of Bus No. 306, which is equipped with wireless charging system, in Changsha, Hunan Province, China. The wireless charging system and electric buses are manufactured by ZTE Corporation (Zhongxing Telecommunication Equipment Corporation) and BYD Company Limited, respectively. In this paper, the operating cycle is quantified and modeled based on experimental data. The real-time bus route and SOC (state of charge) during daytime operation are recorded with the help of GPS (global position system) and BMS (battery management system). The wireless charging process is tested with a power analyzer and its charging efficiency is compared with a plug-in system. Besides, the radiation level while charging is also taken into consideration. Currently, the buses are designed to operate in daytime and get charged at night.

Engine torque fluctuation is a great threat to vehicle comfort and durability. Former researches tried to solve this problem by introducing active damping system, which means the motor is controlled to produce torque ripple with just the opposite phase to that of the engine. By this means, the torque fluctuation produced by the motor and the engine can be reduced. In this paper, a new method is raised. An attempt is proposed by changing the traditional structure of the motor, making it produce ripple torque by itself instead of controlling the motor. In this way a special used ISG (Integrated Starter Generator) motor for HEV (Hybrid Electrical Vehicles) is made to achieve active damping. In order to study the possibility, a simulation, which focus on the motor instead of the whole system, is developed and series-parallel configuration is used in this simulation. As for the motor that used in this paper, four kinds of motors have been investigated and compared.

Pilot ignited natural gas diesel engine (PINGDE) was demonstrated to achieve low NOx emission, high fuel economy and low fuel cost. Despite of that, PINGDE is still confronted with problems such as high mechanical and thermal stress under heavy load, high CO and THC emission under small load and a trade-off relationship between NOx emission and fuel efficiency for whole operating points. In this study, tests were conducted to explore how three main variables including pilot injection timing, pilot diesel substitution rate and two kinds of pilot injection strategies influence the performance and emission of the modified WP10 engine. Two pilot injection strategies including pilot diesel injected once and twice were proposed and potential of promoting fuel economy and saving fuel cost was demonstrated. Moreover, a numerical engine model is established to optimize engine performance and emission with the help of MBC toolkit through limited experiments.

This study investigates the performance of a diesel engine fueled with naphtha under different load by varying injection parameters and exhaust gas recirculation (EGR) rate. The experiments were conducted on a 1.9-liter common rail diesel engine with a compression ratio of 17.5. Naphtha with a research octane number of 60.5 was tested. Three multi-injection strategies were designed. Each injection strategy, aided with EGR, conducts a characteristic combustion mode. Multi-injection strategies and single-injection strategy were tested and compared at one operating point under different main injection timing and EGR conditions. Results indicate that the well-designed multi-injection strategy has advantages over the single injection strategy in lowering noise, emissions and improving combustion efficiency. Among the three strategies, the strategy with 15-degree pilot timing and 2mg/cycle pilot injection could achieve both low NOx and PM emissions without sacrificing much fuel efficiency.

There is increasing demand for engine diagnostic and control with in-cylinder pressure signal. However, the application of cylinder pressure sensors are restricted by the high cost of the sensor. Another possible way for engine combustion state estimation is by processing of instantaneous crankshaft speed signal, but it is limited by the precision and complexity of the algorithm. It could be a solution by processing one cylinder pressure signal in combination with a crankshaft speed signal. The indicated torque could be estimated through engine speed processing and also from the measure cylinder pressure for the reference cylinder. Measurement results from experiments show that the indicated torque error traces of different cylinder are similar in shape. According to this assumption, the reference cylinder with cylinder pressure signal available can serve as both a parameter calibration information source and an error reduction measure.

Experimental research were carried out on a compression ignition engine with compression ratio of 17.5 with direct-run Naphtha. Exhaust recirculation ratio sweeps were carried out with three injection strategies. Premixed charge compression ignition, partially premixed combustion and low temperature combustion modes were realized and compared with each other. The first injection strategy is single injection. The injection timing is scanned to form partially premixed combustion and low temperature combustion. The second injection strategy features a large early first injection with fixed timing to form premixed charge and a small second injection near top dead center, which was scanned. The third injection strategy is similar to the traditional diesel injection strategy, which has a small pilot injection with fixed interval before the main injection. Results show that all injection strategies could realize both low NOx and low particulate matter emissions simultaneously.

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.

This paper was targeted on achieving in-cycle real-time prediction of NOx emission of diesel engines in both steady-state and transient processes based on cylinder pressure. Specifically, input parameters of the NOx emission model were determined, an offline empirical model of NOx emission was built based on steady-state test data, and in-cycle real-time prediction of NOx emission was achieved in the in-cylinder combustion analysis tool. Based on the mechanism of NOx formation, combustion state parameters in strong correlation with NOx emission were extracted from cylinder pressure, rate of cylinder pressure, rate of heat release, accumulated heat release and burned zone temperature. Quantitative correlations between combustion state parameters and NOx emission were calculated based on steady-state test data and the inputs of the empirical model of NOx emission were determined.

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.

In-cylinder pressure sensor, which provides the means for precise combustion control to achieve improved fuel economy, lower emissions, higher comfort, additional diagnostic functions etc., is becoming a necessity in future diesel engines, especially for chemical-kinetics dominated PCCI (Premixed Charge Compression Ignition) or LTC (Low Temperature Combustion) engines. In this paper, new control strategy is investigated to utilize in-cylinder pressure information into engine start process, in order to guarantee the success of engine start and in the meantime prevent penalty of fuel economy or pollutant emissions due to excessive fuel injection. An engine start acceleration model is established to analyze the engine start process. “In-cylinder Combustion Analysis Tool” (i-CAT), is used to acquire and process the in-cylinder pressure data and deliver the combustion indices to ECU (Engine Control Unit). Feedback control is accomplished in ECU based on this information.

Advanced compression ignition combustion system which reduces simultaneously both nitride oxides (NOx) and particulate matter (PM) is a promising approach to meet future emission regulations. In order to achieve advanced compression ignition, flexible fuel injection is required for ultra-early and post-TDC injections, which conventional injector fails to accomplish due to wall-wetting effect. In this work, special injectors with the spray angle of 60 degree are applied on a 4 cylinder mass-production diesel engine without modification of the engine configuration. For application-oriented study, sweep experiments of injection timings and durations, fuel injection pressure and the boost pressure are carried out to investigate the relationships between the control parameters and the engine performance. Model based calibration and real application tests validate the maximum applicable operation range of maximum speed of 2200 RPM and IMEP of 8.0 bar.

Due to the high cost of torque sensors, a calculation model of transient torque is required for real-time coordinating control purpose, especially in hybrid electric powertrains. This paper presents a feedforward calculation method based on mean value model of turbocharged non-EGR diesel engines. A fitting variable called fuel coefficient is defined in an affine relation between brake torque and fuel mass. The fitting of fuel coefficient is simplified to depend only on three variables (engine speed, boost pressure, injected fuel mass). And a two-layer feedforward neural network is utilized to fit the experimental data. The model is validated by load response test and ETC (European Transient Cycle) transient test. The RMSE (root mean square error) of the brake torque is less than 3%.

Classification of diagnosis knowledge for Common Rail System(CRS) was investigated in this paper. Main fault modes and judgement regulations of CRS were confirmed throng principle of expert system. A scan tool was designed to communicate with vehicle Electronic Control Unit(ECU), and data link between scanner and ECU was realized through K-line communication, moreover, diagnosis program was accomplished based on Key Word Protocol 2000(KWP2000). This study focused on methods to validate faults of CRS based on expert system. Method advanced was effective on fault diagnosis because expert system had capability of intellectual faculties. Finally, experiments were carried out on a six-cylinder diesel.

Many factors will influence injector's performance, and correlation among them is very complicated after experiments of Electronic-controlled Injector(ECI) were carried out. Equilibrium algorithm based on Self Adaptive Fuzzy Control(SAFC) was put forward to ensure consistency of injectors and remedy shortages of static compensation algorithm. Model of Common Rail System(CRS) was created under MATLAB/SIMULINK. It was showed by experiment results SAFC algorithm had good effects on reducing speed unevenness of each cylinder, and it was found that effect for reducing unevenness when speed was over 1600 rpm was not very remarkable compared with below 1000 rpm for the diesel used for experiments.

The high emission level during start-up process of common rail diesel engine is still a problem for ultra low emission control. For the map-based common rail system, engine start-up process goes through the initialization of injection and rail pressure build-up process, so the fuel injection status is not stable. Based on the analysis of the characteristics of rail pressure build-up, engine speed variety and exhausted smoke emission during engine start-up process, it is found that the injection parameters of the initial phase of engine start-up have large effects on the start-up time and smoke emission. To optimize the smoke emission, this paper makes a study on the methods of determining the injection parameters during start-up by means of well-phased investigation of engine speed and orthogonal bench test. The research is carried out on a 6-cylinder 7.8L turbocharged diesel engine equipped with a DENSO ECD-U2 common-rail system.

Emission control is a focus of Diesel technology development all over the world. EGR is considered as a most efficient method to reduce the NOx exhausted and there has also been published a significant amount of studies on EGR. As one part of evaluation of engine technologies of PNGV plan, this research tried to investigate comprehensively what effects cooled and hot EGR imposes on exhaust emissions in a developing light duty high-speed direct injection (HSDI) Diesel engine equipped with high-pressure common rail (HPCR) multiple-stage injection system, VNT and cooled/hot EGR. The test is carried out on a 3-cylinder CR engine. In the condition of the other control parameters being optimized, EGR map is adjusted for different EGR rate. Then, the effect of EGR on emissions is investigated under different EGR rates.