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SI-CAI hybrid combustion, also known as spark-assisted compression ignition (SACI), is a promising concept to extend the operating range of CAI (Controlled Auto-Ignition) and achieve the smooth transition between spark ignition (SI) and CAI in the gasoline engine. In order to stabilize the hybrid combustion process, the port fuel injection (PFI) combined with gasoline direct injection (GDI) strategy is proposed in this study to form the in-cylinder fuel stratification to enhance the early flame propagation process and control the auto-ignition combustion process. The effect of bowl piston shapes and fuel injection strategies on the fuel stratification characteristics is investigated in detail using three-dimensional computational fluid dynamics (3-D CFD) simulations. Three bowl piston shapes with different bowl diameters and depths were designed and analyzed as well as the original flat piston in a single cylinder PFI/GDI gasoline engine.

Modeling techniques matter a lot in many fields of engine engineering. Models are requested not only for control design but also for dynamic prediction. However, problems might be encountered during modeling process either because of the system complexity or the unaffordable modeling cost. As a result, a new modeling technique based on disturbance estimation is proposed in this paper. By employing the proposed modeling technique, models are set up in real time with the online information from input and output. The uncertainties of system dynamics are handled as internal disturbance of the system, while the perturbation from outside are taken as the external disturbance, and the combination of the two can be estimated online by a kind of active observer called extended state observer (ESO).

The increasingly stringent requirements in relation to emission reduction and onboard diagnostics are pushing the Chinese automotive industry toward more innovative solutions and a rapid increase in electronic control performance. To manage the system complexity the architecture will require being well structure on hardware and software level. The paper introduces GEMS-K1 (Gasoline Engine Management System - Kit 1). GEMS-K1 is a platform being compliant with Euro IV emission regulation for gasoline engines. The application software is developed using modeling language, the code is automatically generated from the model. The driver software has a well defined structure including microcontroller abstraction layer and ECU abstraction layer. The hardware is following design rules to be robust, 100% testable and easy to manufacture. The electronic components use the latest innovation in terms of architecture and technologies.

Homogeneous Charge Compression Ignition (HCCI) has the potential of reducing fuel consumption as well as NOx emissions. However, it is still confronted with problems in real-time control system and control strategy for the application of HCCI, which are studied in detail in this paper. A CAN-bus-based distributed HCCI control system was designed to implement a layered close loop control for HCCI gasoline engine equipped with 4VVAS. Meanwhile, a layered management strategy was developed to achieve high real-time control as well as to simplify the couplings between the inputs and the outputs. The entire control system was stratified into three layers, which are responsible for load (IMEP) management; combustion phase (CA50) control and mechanical system control respectively, each with its own specified close loop control strategy. The system is outstanding for its explicit configuration, easy actualization and robust performance.

FIRCRI-a flexible injection rate common rail injector was developed. This paper presents the working principle and the configuration of the injector. As key technologies in development of the injector, a new fast response solenoid valve was developed and 4 dimensionless design parameters of hydraulic system were presented by through computer simulation and experimental study. The solenoid valve was deliberately designed so as to eliminate the hydraulic force acting on the valve. Other configuration parameters were also optimized so that the response time of the solenoid valve is 0.3 ms. It is interesting to find that the response time of the injector is not only determined by the solenoid valve, but all parameters of the hydraulic system of the injector. The injector can realize pilot injection, which is less than 2.5mm3, at a controllable phase and multi-injections.

The aim of this paper is to compile the state of the art of engine control and develop scenarios for improvements in a number of applications of engine control where the pace of technology change is at its most marked. The first application is control of downsized engines with enhancement of combustion using direct injection, variable valve actuation and turbo charging. The second application is electrification of the powertrain with its impact on engine control. Various architectures are explored such as micro, mild, full hybrid and range extenders. The third application is exhaust gas after-treatment, with a focus on the trade-off between engine and after-treatment control. The fourth application is implementation of powertrain control systems, hardware, software, methods, and tools. The paper summarizes several examples where the performance depends on the availability of control systems for automotive applications.

Homogeneous charge compression ignition (HCCI) technology is promising to reduce engine exhaust emissions and fuel consumption in gasoline engine. However, it is still confronted with the problem of its limited operation range. High load is limited by the tradeoff between the quantity of working charge and dilution charge. Low load is limited by the high residual gas fraction and low temperature in the cylinder. One of the highlights of HCCI combustion research at present is to expand the low load limit of HCCI combustion by developing HCCI idle operation. The main obstacle in developing HCCI idle combustion is too high residual gas fraction and low temperature to misfire in cylinder. This paper relates to a method for achieving the appropriate environment for auto-ignition at idle and the optimal tradeoff between the combustion stability and fuel consumption by employing EIVO valve strategy with an equivalent air-fuel ratio.

Homogeneous charge compression ignition (HCCI) technology is promising to reduce engine exhaust emissions and fuel consumption. However, it is still confronted with the problem of its narrow operation range that covers only the light and medium loads. Therefore, to expand the operation range of HCCI, mode switching between HCCI combustion and transition SI combustion is necessary, which may bring additional problems to be resolved, including load fluctuation and increasing the complexity of control strategy, etc. In this paper, a continuously adjustable load strategy is proposed for gasoline engines. With the application of the strategy, engine load can be adjusted continuously by the in-cylinder residual gas fraction in the whole operation range. In this research, hybrid combustion is employed to bridge the gaps between HCCI and traditional SI and thus realize smooth transition between different load points.

SI-CAI hybrid combustion, also known as spark-assisted compression ignition (SACI), is a promising concept to extend the operating range of CAI (Controlled Auto-Ignition) and achieve the smooth transition between spark ignition (SI) and CAI in the gasoline engine. In order to investigate the effect of the thermal boundary condition on the hybrid combustion, the experiments with different coolant temperatures are performed to adjust the chamber wall temperature in a gasoline engine. The experimental results indicate that increasing wall temperature would advance the combustion phasing, enlarge the peak heat release rate and shorten the combustion duration. While the capacity of the wall temperature effect on the hybrid combustion characteristics are more notable in the auto-ignition dominated hybrid combustion.

Approximately 50% energy is consumed during the acceleration of a city bus. Fuel consumption during acceleration is significantly affected by driving behavior. In this study, 13 characteristic parameters were selected to describe driving style based on analysis of how driving influences fuel consumption during acceleration. The 100,000 km real-world vehicle running data of six drivers on three city buses in a particular bus line in Tianjin, China were sampled using a vehicle-on-line data logger. Based on the selected characteristic parameters and collected driving data, an evaluation model of the fuel consumption level of a driver was established by adopting the method of decision tree C4.5. For two-level classification, the model has over 85% prediction accuracy. The model also has the advantages of having a few training samples and strong generalization. As an example of the model application, the fuel-saving potential of a driver under optimal operations was analyzed.

A pressure accumulative injection rate controllable unit injector-PAIRCUI is proposed and developed. This unit injector is powered by fuel pressure accumulation controlled by an electronic control unit and its injection rate is shaped by inner valves of the injector. Inherent advantages of an accumulator type unit injector have been carried out in this new design, including sructural simplicity, totally flexible injection timing, medium common rail pressure, tolerable pump size and flow requirement. A number of decisive features have also been realized that are significant for high efficiency and low emissions of engine combustion, including higher mean effective injection pressure(MEIP), pilot injection capability and rapid end of injection. The injection pressure is independent of engine speed, but regulated upon engine load. These characteristics are beneficial in improving engine performance and fuel consumption.

In the last few years, residual gas trapping has been widely used to achieve CAI combustion operation in the four-stroke gasoline engine by means of the negative valve overlap period. In this paper, a flexible mechanical variable valve actuation system based on the production technologies is described. The 4VVAS system is capable of independent control of intake valve lift and its timing, exhaust valve lift and its timing and it has been incorporated in a specially designed cylinder head for a single cylinder research engine. In addition, an engine simulation program has been developed to investigate the potential of the 4VVAS system for CAI engine operation and the switch between CAI and SI operations on the same engine. The engine simulation program is written with Matlab Simulink and incorporates an engine block, a newly developed CAI ignition and heat release model, a valve profile generator, and an engine control module for spark ignition and fuelling control.

The effects of jet impingement and turbulence structure on jet mixing rate arc investigated by using a simultaneous measurement system of concentration and velocity. It is found that, after the end of injection, dispersion of momentum of a CO2 jet Is much faster than that of concentration. The residual gas is then left in a rather quiescent atmosphere, that makes a sluggish mixing process of the residual gas. Jet impingement can create intensive air motion in the near impingement region, that promotes the mixing of the residual gas. However, the effect of jet impingement decreases as the distance from the impingement point increases.

It is found that a thin and rich mixture layer on a wall is formed after impingement of a gas jet of fuel on the wall. The measured thickness of the mixture layer is about 2 mm. and its dispersion rate after the end of injection is much lower, compared to that of a space gas jet. This phenomenon in a small D.I. diesel engine is known as “wall wetting” or “wall fuel accumulation” which has an important influence on engine fuel consumption and emissions. This paper presents a technique for enhancing the near wall mixing of an impinging jet by means of a bump on the wall. The development of a wall jet formed after an impingement of a gas jet has been investigated by simultaneously measuring the near wall velocity and concentration distribution. It has been found that a wall jet is stripped off the wall and ejected as a secondary jet when the wall jet encounters a bump of the wall.

The present paper aims to investigate the influence of spark ignition on CAI combustion based on internal EGR strategy. Controlled Auto-ignition (CAI) combustion is facilitated in a Ricardo single cylinder engine with a pair of special camshafts, which valve lift and cam profile are modified to trap enough hot residuals. Operation regions and other detailed combustion characteristics of the CAI engine operation are analyzed and compared between pure CAI mode and the CAI mode with assisted spark ignition. The results show that spark ignition can play an important role in controlling CAI combustion ignition in low load boundary region. The low temperature chemical reaction process is shortened and the auto ignition timing is advanced due to the spark discharge. Meantime, lower fuel consumption and cycle-to-cycle variations can be achieved.

The RCS (Rankine cycle system) used to recover the exhaust gas energy from internal combustion engines has been regarded as one of the most promising ways to achieve higher efficiency. However, it is a big challenge to keep the RCS still in good performance under variable driving cycle. This paper aims at revealing the reasons resulting in the low efficiency under driving cycle, comparing to that under steady-state condition. The dynamic operating process of the RCS under driving cycle is analyzed, and then the RCS applied on an 11.6L heavy duty diesel engine is modeled. Based on that, the dynamic performance of the RCS under an actual driving cycle is discussed. The results indicate that the average efficiency under a piece of Tianjin bus driving cycle is as low as 3.63%, which is less than half of that (7.77%) under the rated point (1300rpm and 50%load). The reasons leading to the low efficiency under driving cycle is interpreted from three aspects.

In decade years, Spark Ignition-Controlled Auto Ignition (SI-CAI) hybrid combustion, also called Spark Assisted Compression Ignition (SACI) has shown its high-efficiency and low emissions advantages. However, high dilution causes the problem of unstable initial ignition and flame propagation, which leads to high cyclic variation of heat release and IMEP. The instability of SI-CAI hybrid combustion limits its dilution degree and its ability to improve the thermal efficiency. In order to solve instability problems and expand the dilution boundary of hybrid combustion, micro flame ignition (MFI) strategy is applied in gasoline hybrid combustion engines. Small amount of Dimethyl Ether (DME) chosen as the ignition fuel is injected into cylinder to form micro flame kernel, which can stabilize the ignition combustion process.

The performance of three different electric turbo-compounding systems under both steady and driving cycle condition is investigated in this paper. Three configurations studied in this paper are serial turbo-compounding, parallel turbo-compounding and electric assisted turbo-compounding. The electric power, global gain of the whole system (engine and power turbine) under steady operating condition is firstly studied. Then investigation under three different driving cycles is conducted. Items including fuel consumption, engine operating point distribution and transient response performance are analyzed among which the second item is done based on statistic method combined with the results obtained under steady operating conditions. Study under steady condition indicates that electric assisted turbo-compounding system is the best choice compared with the other two systems. The performance of serial turbo-compounding is load oriented while parallel configuration is speed oriented.