Search Results

Future government emission regulations have lead to the development and implementation of advanced aftertreatment systems to meet stringent emission standards for both on-road and off-road vehicles. These aftertreatment systems require sophisticated control and diagnostic strategies to ensure proper system functionality while minimizing tailpipe NOx and PM emissions across all engine operating conditions. In this paper, an integrated algorithm design approach with controls and diagnostics for an aftertreatment system consisting of a fuel doser, fuel reformer, LNT, DPF, and SCR is discussed.

Reactivity Controlled Compression Ignition (RCCI) has been shown to be an attractive concept to achieve clean and high efficiency combustion. RCCI can be realized by applying two fuels with different reactivities, e.g., diesel and gasoline. This motivates the idea of using a single low reactivity fuel and direct injection (DI) of the same fuel blended with a small amount of cetane improver to achieve RCCI combustion. In the current study, numerical investigation was conducted to simulate RCCI and HCCI combustion and emissions with various fuels, including gasoline/diesel, iso-butanol/diesel and iso-butanol/iso-butanol+di-tert-butyl peroxide (DTBP) cetane improver. A reduced Primary Reference Fuel (PRF)-iso-butanol-DTBP mechanism was formulated and coupled with the KIVA computational fluid dynamic (CFD) code to predict the combustion and emissions of these fuels under different operating conditions in a heavy duty diesel engine.

The dual-fuel Reactivity Controlled Compression Ignition (RCCI) combustion could achieve high efficiency and low emissions over a wide range of operating conditions. However, further high load extension is limited by the excessive pressure rise rate and soot emission. Polyoxymethylene dimethyl ethers (PODE), a novel diesel alternative fuel, has the capability to achieve stoichiometric smoke-free RCCI combustion due to its high oxygen content and unique molecule structure. In this study, experimental investigations on high load extension of gasoline/PODE RCCI operation were conducted using late intake valve closing (LIVC) strategy and intake boosting in a single-cylinder, heavy-duty diesel engine. The experimental results show that the upper load can be effectively extended through boosting and LIVC with gasoline/PODE stoichiometric operation.

Considering the defect of current test method and learning from the developing experience of other methods around the world, a method adopted China Light-duty Vehicle Test Cycle (CLTC) which is suitable for the real condition of Chinese road was put forword. Through comparing the test results of 20 vehicles with big data statistics, the results obtained by this method are close to those from customers and the difference between them is around 6%. Thus, the rationality of this method is proved. Furthermore, this method can evaluate the real fuel consumption of vehicle running on Chinese roads.

This work numerically investigates the detailed combustion kinetics of partially premixed combustion (PPC) in a diesel engine under three different premixed ratio fuel conditions. A reduced Primary Reference Fuel (PRF) chemical kinetics mechanism was coupled with CONVERGE-SAGE CFD model to predict PPC combustion under various operating conditions. The experimental results showed that the increase of premixed ratio (PR) fuel resulted in advanced combustion phasing. To provide insight into the effects of PR on ignition delay time and key reaction pathways, a post-process tool was used. The ignition delay time is related to the formation of hydroxyl (OH). Thus, the validated Converge CFD code with the PRF chemistry and the post-process tool was applied to investigate how PR change the formation of OH during the low-to high-temperature reaction transition. The reaction pathway analyses of the formations of OH before ignition time were investigated.

A fully coupled multi-dimensional CFD and reduced chemical kinetics model is adopted to investigate the effects of charge stratification on HCCI combustion and emissions. Seven different kinds of imposed stratification have been introduced according to the position of the maximal local fuel/air equivalence ratio in the cylinder at intake valve close. The results show that: The charge stratification results in stratification of the in-cylinder temperature. The former four kinds of stratification, whose maximal local equivalence ratios at intake valve close locate between the cylinder center and half of the cylinder radius, advance ignition timing, reduce the pressure-rise rate, and retard combustion-phasing. But the following three kinds of stratification, whose maximal local equivalence ratios at intake valve close appear between half of the cylinder radius and the cylinder wall, have little effect on the cylinder pressure.

The effects of various injection timing of methanol on thermo-atmosphere combustion of methanol by port injection of dimethyl ether (DME) and direct injection of methanol were experimentally investigated. The experiment results show that, as injection timing is at 6 degree before TDC, the combustion process comprises three stages: low temperature heat release of DME, high temperature heat release of DME and diffusion combustion of methanol. As injection timing increases, premixed combustion proportion of methanol is increased and diffusion combustion proportion is decreased. As injection timing increases to 126 degree before TDC, diffusion combustion of methanol disappears. At this time, the combustion process shows typical two stages heat release of HCCI combustion. As injection timing increases, required DME rate is increased, combustion efficiency and indicated thermal efficiency all first increase and then decrease.

A HCCI engine has been run at different operating boundaries conditions with fuels of different RON and MON and different chemistries. The fuels include gasoline, PRF and the mixture of PRF and ethanol. Six operating boundaries conditions are considered, including different intake temperature (Tin), intake pressure (Pin) and engine speed. The experimental results show that, fuel chemistries have different effect on the combustion process at different operating conditions. It is found that CA50 (crank angle at 50% completion of heat release) shows no correlation with either RON or MON at some operating boundaries conditions, but correlates well with the Octane Index (OI) at all conditions. The higher the OI, the more the resistance to auto-ignition and the later is the heat release in the HCCI engine. The operating range is also correlation with the OI. The higher the OI, the higher IMEP can reach.

“Soichiro Honda Cup, Honda Econo-Power Competition”, is an annual international energy-saving competition which is hosted by Honda Motor Co., Ltd. Till now it has been held 27 sessions. The aims of the EP project are: promoting the development of environmental protection, making full use of limit earth resources, challenging the fuel consumption limitation of vehicle. Tongji University's students' team has participated in the competition for seven consecutive times. In order to minimize the fuel consumption of the EP energy-saving vehicle, this paper focuses on the technical methods of improving the fuel economy of the engine. Firstly, the optimization of the carburetor. Secondly, for the purpose of improving combustion efficiency, researches on dual spark plug and compression ratio are done.

The influence of boost pressure (Pin) and fuel chemistry on combustion characteristics and performance of homogeneous charge compression ignition (HCCI) engine was experimentally investigated. The tests were carried out in a modified four-cylinder direct injection diesel engine. Four fuels were used during the experiments: 90-octane, 93-octane and 97-octane primary reference fuel (PRF) blend and a commercial gasoline. The boost pressure conditions were set to give 0.1, 0.15 and 0.2MPa of absolute pressure. The results indicate that, with the increase of boost pressure, the start of combustion (SOC) advances, and the cylinder pressure increases. The effects of PRF octane number on SOC are weakened as the boost pressure increased. But the difference of SOC between gasoline and PRF is enlarged with the increase of boost pressure. The successful HCCI operating range is extended to the upper and lower load as the boost pressure increased.

Among various applications of the automotive engine and chassis controls, PWM driven actuators and valves are commonly used, such as an electronic throttle control in both gasoline and diesel engines, variable valve timing control, EGR control, proportional valve regulating pressures, and etc. Many of such valves are used under the conditions of uncertainties, disturbances, frictions, wear and tear, system aging, and sensor noises as well. Maintaining system functions with high performance under such tough environments and through out the full useful life cycle, is highly desirable but very challenging for control designs. Additional component issues such as electronic signal drifting, mechanical hysteresis, frictions will just add another level of difficulties. In this paper, we proposed a unique and practical control strategy which is relatively easy to implement, however still able to provide us with advantages in handling robustness.

Exhaust Gas Recirculation (EGR) is an important parameter for control of diesel engine combustion, especially to achieve ultra low NOx emissions. In this paper, the effects of EGR on engine emissions and engine efficiency have been investigated in a heavy-duty diesel engine while changing combustion control parameters, such as injection pressure, injection timing, boost, compression ratio, oxygenated fuel, etc. The engine was operated at 1400 rpm for a cycle fuel rate of 50mg. The results show that NOx emissions strongly depend on the EGR rate. The effects of conventional combustion parameters, such as injection pressure, injection timing, and boost, on NOx emissions become small as the EGR rate is increased. Soot emissions depend strongly on the ignition delay and EGR rate (oxygen concentration). Soot emissions can be reduced by decreasing the compression ratio, increasing the injection pressure, or burning oxygenated fuel.

This paper addresses Hardware-In-the-Loop modeling and simulation for Diesel aftertreatment controls system development. Lean NOx Trap (LNT) based aftertreatment system is an efficient way to reduce NOx emission from diesel engines. From control system perspective, the main challenge in aftertreatment system is to predict temperature at various locations and estimate the stored NOx in LNT. Accurate estimation of temperatures and NOx stored in the LNT will result in an efficient system control with less fuel penalty while still maintaining the emission requirements. The optimization of the controls will prolong the lifespan of the system by avoiding overheating the catalysts, and slow the progressive process of component aging. Under real world conditions, it is quite difficult and costly to test the performance of a such complex controller by using only vehicle tests and engine cells.

In recent years, due to more and more stringent government regulations on diesel emissions, diesel aftertreatment systems have attracted great deal of attention from both academia and diesel engine industries. Many different devices and approaches, such as Urea SCR, LNT, engine control related EGR and in-cylinder post injection, have been developed and applied to reduce nitrogen oxides (NOx) emissions. Among those solutions, Lean NOx Trap (LNT)-based emission reduction control system is one of the common approaches. The NOx storage capacity of an LNT depends on many different factors and operating conditions. Accurate and real-time estimation of NOx storage is quite important for efficient system controls, particularly for enhancing system lifespan and reducing overall fuel consumption. A more precise modeling of NOx storage has more significant impact for overall system performance.

The purpose of this study was to gain a better understanding of the effects of port fuel injection strategies and thermal stratification on the HCCI combustion processes. Experiments were conducted in a single-cylinder HCCI engine modified with windows in the combustion chamber for optical access. Two-dimensional images of the chemiluminescence were captured using an intensified CCD camera in order to understand the spatial distribution of the combustion. N-heptane was used as the test fuel. The experimental data consisting of the in-cylinder pressure, heat release rate, chemiluminescence images all indicate that the different port fuel injection strategies result in different charge distributions in the combustion chamber, and thus affect the auto-ignition timing, chemiluminescence intensity, and combustion processes. Under higher intake temperature conditions, the injection strategies have less effect on the combustion processes due to improved mixing.

A yc6112ZLQ turbocharged 6 cylinder engine with intercooler was converted to operate in dual fuel mode with compressed natural gas (CNG) and pilot diesel. The influence of the CNG ratio, pilot diesel injection advance (ADC) and intake temperature after intercooler on the combustion process, emissions and engine performance was investigated. The results show that the combustion process of dual-fuel engines is faster than diesel engine. Both the ignition timing of the pilot fuel and the excess air ratio of total fuel λ dominate the combustion characteristics of duel-fuel engines. With the increase of CNG ratio, the pressure and temperature in cylinder decrease at rated mode, but increase at torque and low speed modes. With advanced the pilot injection timing or increased the intake temperature, the cylinder pressure and temperature increase.

Studies on combustion process of Dimethyl Ether (DME) were carried out on a constant volume combustion bomb (CVCB) and a visualization engine, and the photograph of combustion of DME was taken by high speed digital CCD. The results show that the ignition delay of DME is shorter than that of diesel fuel. When the fuel delivery amounts of DME and diesel in volume are the same, the combustion duration of DME is shorter than that of diesel fuel, and the flame temperature of DME is lower than that of diesel. At the end of combustion, the second injection occurred. The results of high-speed photograph in visualization engine show that, as soon as DME leaves the nozzle, it evaporates rapidly, and under the effect of air swirl, the spray“core” is blown off. Compared to diesel, the penetration of DME is shorter, and the wall combustion of DME is apparently smaller.

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.

This paper addresses feedforward tracking control for electronic throttles. A robust and accurate tracking control scheme based on the training of a Neural Network model and feedback term (PID) is developed. The Neural Network based term can be trained off-line. This feedfoward term serves as a mathematical model capable of describing Electronic Throttle dynamics over a wide range. We have shown that by adding the Neural Network based feedforward control to a common feedback control method, such as the gain-scheduled PID used in many ETC production controllers, that the tracking control performance criteria such as transient errors, steady state errors, response time and overshoot, are greatly improved. Experiments conducted on a production Electronic Throttle Body with a Motorola H-brigde driver IC have shown good results utilizing this approach.

In this paper, we discuss the mathematical modeling of suspension and rollover characteristics. With dynamics analysis, a simple active suspension control is designed with rollover prevention. Also studied is the framework of how to integrate active suspension and steering in the emergency situations besides regular ride and handling suspension control. Simulation results are presented.