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Exhaust gas recirculation valves used in internal combustion engines are highly nonlinear due to its nonlinear mechanism and dry friction dominated at low valve speed that could lead to large steady-state displacement errors. A multiple friction factor model is adopted in this article using a switched linear parameter-varying (LPV) modeling approach, where the scheduling parameter is the friction coefficient as a function of valve speed. Switched gain-scheduling LPV controllers are designed based on the hysteresis switching logic with guaranteed ${\mathscr{H}}_{\infty }$ performance, where parameterized linear matrix inequality (LMI) conditions are relaxed to a set of LMI conditions for synthesizing the switched LPV controllers by convex optimization. The LPV control performance is compared with that of proportional–integral–derivative controllers through both simulation and experimental studies, showing a notable improvement in the system response performance and robustness. [ABSTRACT FROM AUTHOR]

The increasing concerns of air pollution and energy usage led to the electrification of the vehicle powertrain system in recent years. On the other hand, internal combustion engines were the dominant vehicle power source for more than a century, and they will continue to be used in most vehicles for decades to come; thus, it is necessary to employ advanced technologies to replace traditional mechanical systems with mechatronic systems to meet the ever-increasing demand of continuously improving engine efficiency with reduced emissions, where engine intake and the exhaust valve system represent key subsystems that affect the engine combustion efficiency and emissions. This paper reviews variable engine valve systems, including hydraulic and electrical variable valve timing systems, hydraulic multistep lift systems, continuously variable lift and timing valve systems, lost-motion systems, and electro-magnetic, electro-hydraulic, and electro-pneumatic variable valve actuation systems. [ABSTRACT FROM AUTHOR]

This paper presents an optimal tracking control of engine valve timing for an electro-hydraulic variable valve actuator utilizing the adaptively estimated supply pressure that is the main source for valve timing variation. The system supply pressure is online estimated through a model-guided adaptive estimator with one-step prediction capability. The estimation model consists of a static guidance model, an in-event valve model, and a one-step prediction model. Using the estimation model, the adaptive estimator generates a nominal estimation with accelerated convergence, estimates the pressure residual error using in-event dynamics, and provides one-step forward pressure prediction along with the resulting pressure fluctuation. The linear quadratic tracking (LQT) control is used to track the desired valve timing based on an event-by-event valve model, where the adaptively estimated pressure variation is used as the feedforward control in the LQT control to improve the tracking accuracy and a Kalman filter is used to estimate the system states for the LQT state feedback control. The parameter estimation and control algorithms are validated through both the simulation and test bench studies by comparing different estimation and control schemes. Both the steady-state and transient operational conditions are investigated, and the effectiveness of the proposed adaptive LQT valve timing control is demonstrated. [ABSTRACT FROM AUTHOR]

The camless valve system is able to provide flexible engine-valve profiles (timing, duration, lift, etc.) to optimize the performance of internal combustion engines. To provide a precise valve profile of an electro-hydraulic variable valve actuator and achieve the desired engine performance, an optimal tracking controller for the valve-rising duration, a key valve profile parameter, is presented in this paper. An event-by-event nonlinear model, connecting the system supply pressure dynamics to the valve-rising duration, is developed and linearized along the desired valve-rising trajectory. Based on the trajectory linearization, a receding horizon linear–quadratic tracking (LQT) controller is designed along with a Kalman optimal state estimation. The equilibrium control resulted from the model linearization is used as the LQT feedforward control. The control performance is compared with that of baseline controllers through both simulation study and bench tests. The transient and steady-state validation results confirm the effectiveness of proposed control scheme. [ABSTRACT FROM AUTHOR]

Combustion phasing control is very important for internal combustion engines to achieve a high thermal efficiency with low engine-out emissions. Traditional open-loop map-based control becomes less favorable in terms of calibration effort, robustness to engine aging, and especially control accuracy for turbulent jet ignition (TJI) engines due to the increased number of control variables over conventional spark-ignition engines. In this paper, a model-based feedforward controller is developed for a TJI engine. A feedback controller is designed based on the linear quadratic tracking control with output covariance constraint. Since the TJI main-chamber combustion is influenced by the prechamber one, the proposed controller optimizes the control variables in both combustion chambers. The proposed feedforward and feedback controller reduces standard deviation of combustion phase by more than 22% over a group of baseline controllers through a series of dynamometer engine tests. [ABSTRACT FROM AUTHOR]

This paper presents experimental investigation results of an electric variable valve timing (EVVT) actuator using linear parameter varying (LPV) system identification and control. For the LPV system identification, a number of local system identification tests were carried out to obtain a family of linear time-invariant (LTI) models at fixed engine speed and battery voltage. Using engine speed and battery voltage as time-varying scheduling parameters, the family of local LTI models is translated into a single LPV model. Then, a robust gain-scheduling (RGS) dynamic output-feedback (DOF) controller with guaranteed H∞ performance was synthesized and validated experimentally. In contrast to the vast majority of gain-scheduling literature, scheduling parameters are assumed to be polluted by measurement noises and the engine speed and battery voltage are modeled as noisy scheduling parameters. Experimental and simulation results show the effectiveness of the developed approach. [ABSTRACT FROM AUTHOR]

A control-oriented engine model is often used in the hardware-in-the-loop (HIL) simulation environment for developing and validating the corresponding control strategies. For homogeneous charge compression ignition (HCCI) combustion, mixture heterogeneity should be considered in the control-oriented model to provide accurate combustion phase prediction. This paper describes a two-zone HCCI combustion model, where the in-cylinder charge is divided into the well-mixed and unmixed zones as the result of charge mixing. Simplified fluid dynamics is used to predict the residual gas fraction before the combustion phase starts, which defines the mass of the unmixed zone, during real-time simulations. The unmixed-zone size determines not only how well the in-cylinder charge is mixed, which affects the start of HCCI combustion, but also the resulting peak in-cylinder pressure and temperature during the combustion process. The developed model was validated in the HIL simulation environment. The HIL simulation results show that the proposed charge mixing and HCCI combustion model provides better agreement with the corresponding GT-Power simulation results than the previously developed one-zone model. [ABSTRACT FROM PUBLISHER]

The combustion mode transition between spark ignition (SI) and homogeneous charge compression ignition (HCCI) combustion of an internal combustion (IC) engine is challenging due to the distinct engine operating parameters over the two combustion modes and the cycle-to-cycle residue gas dynamics during the mode transition. The control problem becomes even more complicated for a multicylinder engine without camless variable valve actuators. This paper studies the combustion mode transition problem of a multicylinder IC engine equipped with dual-stage valve lift and electrical variable valve timing (VVT) systems. Hardware-in-the-loop (HIL) simulations were used as a tool to develop and validate the proposed control strategies. Based on the HIL simulation results, this paper shows that smooth combustion mode transition can be realized in a few engine cycles. During the mode transition, a model-based linear quadratic tracking strategy was used to track the desired engine manifold pressure through the engine throttle control to maintain the engine AFR in a desired range; the fuel quantity of individual cylinder was controlled via the iterative learning; and engine spark was maintained for the SI–HCCI (or spark assistant) hybrid combustions during the combustion mode transition. The HIL simulations demonstrated the effectiveness of the developed control strategies under both steady state and transient engine operating conditions. As a result, it is feasible to have a smooth combustion mode transition for an HCCI capable SI engine equipped with dual-stage valve lift and electrical VVT systems. [ABSTRACT FROM AUTHOR]

Electro-pneumatic valve actuators are used to eliminate the cam shafts of a traditional internal combustion engine. They are used to control the opening timing, duration, and lift of both intake and exhaust valves. In order to develop model-based control strategies, a control oriented model was developed by piecewisely linearizing the physics-based nonlinear system model. In this paper, an adaptive valve lift control strategy was developed to improve the intake valve lift repeatability. The model reference adaptive system identification technique was employed to estimate system parameters needed for generating feedforward control signals for the closed-loop control scheme. The closed-loop lift control strategies, along with the model reference feedforward control, were developed and implemented in a prototype controller, and validated on a valve test bench with multiple reference valve lifts at both 1200 and 5000 r/min engine speeds. The experiment results showed that the actual valve lift reached the reference lift within 0.5 mm of lift error in one cycle at 1200 r/min and in two cycles at 5000 r/min. The maximum steady-state lift errors were less than 0.4 mm at high valve lift and less than 1.3 mm at low valve lift. Furthermore, the closed-loop valve lift control improved valve lift repeatability with more than 30% reduction of standard deviation over the open-loop control. [ABSTRACT FROM AUTHOR]

This paper presents a detailed model of a novel electropneumatic valve actuator for both engine intake and exhaust valves. The valve actuator's main function is to provide variable valve timing and variable lift capabilities in an internal combustion engine. The pneumatic actuation is used to open the valve and the hydraulic latch mechanism is used to hold the valve open and to reduce valve seating velocity. This combination of pneumatic and hydraulic mechanisms allows the system to operate under low pressure with an energy saving mode. It extracts the full pneumatic energy to open the valve and use the hydraulic latch that consumes almost no energy to hold the valve open. A system dynamics analysis is provided and followed by mathematical modeling. This dynamic model is based on Newton's law, mass conservation, and thermodynamic principles. The air compressibility and liquid compressibility in the hydraulic latch are modeled, and the discontinuous nonlinearity of the compressible flow due to choking is carefully considered. Provision is made for the nonlinear motion of the mechanical components due to the physical constraints. Validation experiments were performed on a Ford 4.6 l four-valve V8 engine head with different air supply pressures and different solenoid pulse inputs. The simulation responses agreed with the experimental results at different engine speeds and supply air pressures. [ABSTRACT FROM AUTHOR]