Modeling and control design of a camless valve actuation system

Abstract

This paper presents the modeling and control design of a new fully flexible engine valve actuation system which is an enabler for camless engines. Unlike existing electromechanical or servo actuated electro-hydraulic valve actuation systems, precise valve motion control is achieved with a hydromechanical internal feedback mechanism. This feedback mechanism can be turned on or off in real-time using simple two state valves which helps reduce the system cost and enables mass production. Since the external control only activates or deactivates the internal feedback mechanism, the trajectory of the entire closed-loop system is purely dependent on the design parameters of the internal feedback system. A mathematical model of the system is developed to evaluate the effect of each of the design parameters. The "Area-schedule" is identified as the key design feature which affects the trajectory of the closedloop system. It needs to be designed systematically to optimize the performance of the system as well as improve its robustness. By treating this feature as the feedback control variable, the design problem is transformed into a nonlinear optimal control problem which is later solved using the numerical dynamic programming method. The effectiveness of the designed areaschedules is verified with simulations.

Development of a novel high-speed actuation mechanism using a magneto-rheological fluid clutch and its application to a fluid control valve

“…Although the design study and testing in this work initially focused on the ECA as an actuator for high-speed hydraulic valves, the characteristics of hydraulic systems (high-power density, large force, and considerable stroke length) may allow the proposed ECA serve as the primary actuator in some other applications. For example, the individually controlled ECAs can replace the traditional cam-follower mechanism to actuate the engine valves in the automotive internal combustion (IC) engine, which will enable the ultimately flexible air-management of an IC engine and thereby improve the fuel efficiency by optimizing the air-delivery for different operating conditions (Gillella and Sun, 2009). The fatigue testing machines for vehicle components (vibration mounts, seats, suspensions, etc.)…”

Use of Variable Valve Actuation to Control the Load in a Direct Injection, Turbocharged, Spark-Ignition Engine

“…First task starts from three validated WAVE [23] engine performance models, a 1.6L and a 2L turbo charged, direct injection Diesel engines and a 4L naturally aspirated, port fuel injection, throttle controlled G100 engine, with computed brake efficiencies and specific fuel consumptions vs. engine speed and brake mean effective pressure within a 5% of measured values. The 2L TDI Diesel above is then used as the baseline for development of the 1.6L E100 and G100 engines.…”

“…be lower, but the use of a stoichiometric air-to-fuel mixture will permit better downsizing. Furthermore, the very well established three way catalytic converter technology may permit to meet emissions standards without the negative impacts on the after treatment technology that the lean stratified operation would introduce [16][17][18][19][20][21][22][23].The electro-hydraulic variable valve actuation technology may be applied to both intake and exhaust valves to fully modify the lift profiles as needed by the engine operation. In addition to valve timing strategies as early intake valve closure or late intake valve opening, valve lift strategies are also possible with variable valve actuation.…”

“…be lower, but the use of a stoichiometric air-to-fuel mixture will permit better downsizing. Furthermore, the very well established three way catalytic converter technology may permit to meet emissions standards without the negative impacts on the after treatment technology that the lean stratified operation would introduce [16][17][18][19][20][21][22][23].…”