Abstract
Research and/or Engineering Questions/Objective
In engines equipped with electromagnetic valve actuator, the throttle valve can be eliminated and the motion of the valves can be flexibly controlled. Thus additional degrees of freedom are added to valvetrain, such as, valve lift and valve opening duration. The objective of this study was to design a controller to regulate the additional degrees of freedom and the cylinder air charge of camless engines, aiming at management of the crankshaft torque output.
Methodology
In order to simplify the controller, the degrees of freedom of valvetrain have been reduced within different engine operating ranges which were divided based on engine speed and load. According to torque-based concept, the relationship among crankshaft torque output, the desired cylinder air charge and the motion parameters of intake valves, such as, valve lift, valve opening time and valve opening duration was studied. Based on the mean value models, and considering some nonlinear factors as experimental data map, the map/physical model was established. Then a feedforward control scheme was designed and the simulation based on Matlab/Simulink was carried out to verify the effectiveness of the controller.
Results
The simulation results demonstrate that the controller has high control precision with low computational complexity, and it can correctly regulate the motion of intake valves within different engine operation ranges to ensure the cylinder air charge is equal to the desired air charge, while significantly reducing the pumping loss, and the crankshaft torque output can track the desired torque output rapidly. At the same time, the engine’s fuel economy and torque output performance are improved, when compared with the traditional engines.
Limitations of this study
The limitation of this study is that the controller is only tested by Matlab/Simulink simulation. In future research, an engine test bench will be established for rapid control prototyping experiment to verify the effectiveness of the controller.
What does the paper offer that is new in the field including in comparison to other work by the authors?
The control scheme for regulating the motion of intake valves and the cylinder air charge of camless engines is new, and the work in this paper lays the foundation of electromagnetic valve actuator for practical applications.
Conclusions
The new control scheme of camless engine intake process has been designed and proved effective.
Key Words : Cylinder air charge; Mean value model; Torque control; Map; Camless engine