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Exhaust gas energy recovery systems have shown great potential in improving internal combustion engine's fuel consumption. The use of porous Si-SiC material as heat storage medium to improve the turbine performance and fuel consumption of the engine has not been investigated. In order to study the effect of porous Si-SiC material as heat storage medium on the fuel consumption for a turbocharged gasoline engine, steady and transient engine conditions were considered. A one-dimensional flow dynamic model of the porous heat storage material was established and comprehensively validated by experimental data. Then, this model was applied to predict the performance of the engine with heat storage medium under various conditions, including steady operation condition at targeted torque and transient operation conditions following the worldwide harmonized light vehicles test cycles. As a result, under steady operation conditions, using heat storage medium, a fuel consumption reduction of about 1.1% was obtained due to increased turbine efficiency and reduced pumping loss. Moreover, the simulation under worldwide harmonized light vehicles test cycle driving cycle achieved fuel consumption saving up to 6.6% at medium vehicle speed due to the reuse of recovered exhaust gas energy in the heat storage medium. Thus, to use of the porous Si-SiC material as a kind of heat storage medium can be deemed as a prominent way to improve the turbine efficiency and engine performance of turbocharged gasoline engines. [ABSTRACT FROM AUTHOR]

Super-knock has been the main obstacle to improve power density and engine efficiency of modern gasoline engines. Previous researches show that the key points of super-knock are composed of pre-ignition and detonation. The former is the inducement and the latter is the root reason why super-knock could damage engines dramatically. Lots of studies have been conducted to suppress super-knock by eliminating pre-ignition. Using a rapid compression machine, this work explores the lean mixture control strategy to eliminate detonation and thus suppressing super-knock. Furthermore, a one-dimensional simulation model was set up to investigate the mechanism of how lean mixture could suppress detonation and super-knock. The experimental and simulation results show that based on detonation and super-knock operating condition, adding 80% additional air while keeping the same fuel energy density could transfer combustion from detonation mode to super-sonic auto-ignitive deflagration mode. The peak pressure and pressure oscillation could be reduced significantly. This indicates that boosted lean burn could suppress detonation and thus suppress super-knock effectively, even if pre-ignition occurs. It could be an effective and practical control strategy to protect modern highly turbocharged gasoline engines. [ABSTRACT FROM AUTHOR]

Innovative air path concepts for turbocharged spark-ignition engines with exhaust gas recirculation impose high demands on the control due to nonlinearities and cross-couplings. This contribution investigates the control of the air and exhaust gas recirculation paths of a two-stage turbocharged spark-ignition engine with low pressure exhaust gas recirculation. Using exhaust gas recirculation at high loads, the in-cylinder temperature can be lowered, reducing the knock tendency, while at the same time preventing the need for the enrichment of the air/fuel ratio. Air and exhaust gas recirculation paths are cross-coupled and show different delay times. To tackle these challenges, a data-based two-stage model predictive controller is proposed: The target selector accounts for the overactuated system structure, while the dynamic controller adjusts the charging pressure and exhaust gas recirculation rate. The prediction model setup is based on a small amount of dyno-run measurement data. To ensure real-time capability, the model is kept as simple as possible. This allows for fast turnaround times of the algorithm, while maintaining the necessary accuracy in steady-state and transient operation. This study focuses on a two-stage control concept based on a target selector for optimal stationary control inputs and the dynamic controller considering the dynamic behavior of the air and exhaust gas recirculation paths. Subsequently, the control concept for the two-stage turbocharged spark-ignition engine with low pressure exhaust gas recirculation is validated via experimental tests under real-driving conditions on an automotive test track, using a prototype test vehicle. Results show that boost pressure as well as exhaust gas recirculation rate setpoints are met without overshoot and control deviation with settling times being close to the boundaries set by the hardware. [ABSTRACT FROM AUTHOR]

The precise boost pressure control is the key to guaranteeing reliable turbocharged gasoline engine operation. The closed-loop control requires fast boost pressure tracking performance in wide engine operating range. This paper presents a double closed-loop nonlinear control scheme to improve transient tracking performance. The air-path system of the turbocharged gasoline engine is described by a physics-based, nonlinear, mean value model that presents a long regulation channel from the control input, waste-gate-opening, to the control output, boost pressure and brings challenges for the controller design with satisfied tracking performance. To address this problem, the outer loop treats the turbine speed as a downstream control demand and adjusts it by using a feedforward-feedback control to achieve fast boost pressure tracking. Subsequently, a disturbance-observer-based nonlinear inner-loop controller is designed to regulate the wastegate that stabilizes the turbine speed tracking error while handles the uncertainties due to operating variation. The stability of the whole closed-loop system is analyzed by the Lyapunov stability theory and the robustness against operating variation is discussed based on input to state stability (ISS). The effectiveness of the proposed controller is validated through a higher fidelity model in AMESim and its performances are compared with well-tuned baseline controllers.

In the upcoming years, more challenging CO2 emission targets along with the introduction of more severe Real Driving Emissions limits are expected to foster the development and the exploitation of innovative technologies to further improve the efficiency of automotive Spark Ignition (SI) engines. Among these technologies, Water Injection (WI), thanks to its knock mitigation capabilities, can represent a valuable solution, although it may significantly increase the complexity of engine design and calibration. Since, to tackle such a complexity, reliable virtual development tools seem to be mandatory, this paper aims to describe a quasi-dimensional approach to model a Port Water Injection (PWI) system integrated in a Turbocharged Direct Injection Spark Ignition (T-DISI) engine. Through a port-puddling model calibrated with 3D-CFD data, the proposed methodology was proven to be able to properly replicate transient phenomena of water wall film formation, catching cycle by cycle the amount of water that enters into the cylinder and is therefore available for knock mitigation. Moreover, when compared with experimental measurements under steady state operating conditions, this method showed good capabilities to predict the impact of the water content on the combustion process and on the knock occurrence likelihood.

Internal Model Control (IMC) has a great appeal for automotive powertrain control in reducing the control design and calibration effort. Motivated by its success in several automotive applications, this work investigates the design of nonlinear IMC for wastegate control of a turbocharged gasoline engine. The IMC design for linear time-invariant (LTI) systems is extended to nonlinear systems. To leverage the available tools for LTI IMC design, the quasi-linear parameter-varying (quasi-LPV) models are explored. IMC design through transfer function inverse of the quasi-LPV model is ruled out due to parameter variability. A new approach for nonlinear inversion, referred to as the structured quasi-LPV model inverse, is developed and validated. A fourth-order nonlinear model which sufficiently describes the dynamic behavior of the turbocharged engine is used as the design model in the IMC structure. The controller based on structured quasi-LPV model inverse is designed to achieve boost-pressure tracking. Finally, simulations on a validated high-fidelity model are carried out to show the feasibility of the proposed IMC. Its closed-loop performances are compared with a well-tuned PI controller with extensive feedforward and anti-windup built in. Robustness of the nonlinear IMC design is analyzed using simulations. [ABSTRACT FROM AUTHOR]

Fault monitoring in internal-combustion engines is crucial for keeping the vehicle performance within the acceptable standards of emission levels and drivers’ demands. This paper analyses how a vehicle’s performance and engine variables are affected by a leakage fault in the exhaust manifold. The threshold leakage that causes the vehicle to exceed the emission standards is determined for a class M1 vehicle tested on a chassis dynamometer over the New European Driving Cycle. It is shown that, when a leakage of 6 mm diameter on the exhaust manifold is introduced, the vehicle emissions exceed those specified in the European 2013 on-board diagnostics standard. In addition, the effects of the said leakage fault on the performance of a 1.7 l turbocharged gasoline engine are analysed at different speed–torque operating points by running the engine in a test cell. The results show that, for this 6 mm leakage, at most operating points the driver cannot notice any reduction in the engine torque. Using the engine performance analysis, a fault effect map for the turbocharged gasoline engine is obtained. This helps to design monitoring algorithms for detection of the exhaust manifold leakage fault. As an application of the map, a strategy is presented on the basis of a comparison between the measured and the estimated pressures downstream of the turbine for the purpose of detecting the exhaust manifold leakage. [ABSTRACT FROM AUTHOR]

HEV (hybrid electric vehicles, HEV) is considered to be one of the most important automotive technical roadmaps. Fuel efficiency level of the engine used in HEV has significant impact on vehicle fuel consumption. This paper studies the performance and fuel economy potential of applying high GCR (geometrical compression ratio, GCR) and cooled EGR in turbocharged gasoline SI engines dedicated to the use in HEVs. A 1-D simulation model for a turbocharged EGR engine has been established based on a baseline 1.5T engine. Then the effects of cooled EGR and higher GCRs on engine combustion and performance have been studied and optimized. As increasing GCR from 9.7:1 to higher values that are 12.5:1 and 14:1, the full load torque decreases obviously with the maximal relative decrease of 7.6% and 21.9% respectively mainly because EGR is used to suppress the knock reducing the volumetric efficiency. The fuel economy in the most speed and load range is greatly improved mainly because of higher constant volume degree, combustion efficiency and less heat transfer and exhaust losses. In HEVs, engines mainly work in the efficient operating range, the torque reduction can be compensated by drive motor, and an appropriately high GCR is advantageous. • 1-D simulation model of turbocharged EGR engine is built. • Variables optimization and turbocharger recalibration are conducted. • Effects of high compression ratio and cooled EGR on combustion are analyzed. • Greatly better fuel economy for turbocharged EGR engine is achieved. • Guidance for development of new dedicated engine for the use in HEV. [ABSTRACT FROM AUTHOR]

In the upcoming years, more challenging CO2 emission targets along with the introduction of more severe Real Driving Emissions limits are expected to foster the development and the exploitation of innovative technologies to further improve the efficiency of automotive Spark Ignition (SI) engines. Among these technologies, Water Injection (WI), thanks to its knock mitigation capabilities, can represent a valuable solution, although it may significantly increase the complexity of engine design and calibration. Since, to tackle such a complexity, reliable virtual development tools seem to be mandatory, this paper aims to describe a quasi-dimensional approach to model a Port Water Injection (PWI) system integrated in a Turbocharged Direct Injection Spark Ignition (T-DISI) engine. Through a port-puddling model calibrated with 3D-CFD data, the proposed methodology was proven to be able to properly replicate transient phenomena of water wall film formation, catching cycle by cycle the amount of water that enters into the cylinder and is therefore available for knock mitigation. Moreover, when compared with experimental measurements under steady state operating conditions, this method showed good capabilities to predict the impact of the water content on the combustion process and on the knock occurrence likelihood. [ABSTRACT FROM AUTHOR]