Linear Parameter-Varying Model of an Electro-Hydraulic Variable Valve Actuator for Internal Combustion Engines

Abstract

This paper presents a novel linear parameter-varying (LPV) model of an electro-hydraulic variable valve actuator (EHVVA) for internal combustion engines that is capable of continuously varying valve timing with dual-lift. The dual-lift is realized mechanically through a hydraulic lift control sleeve; valve opening (VO) terminal and closing seating velocities are regulated using a top or bottom snubber; and opening and closing timings, as well as lift profile area, are controlled by the valve actuation timing and hydraulic supply pressure. First, nonlinear mathematical system model is developed based on the Newton's law, orifice flow equation, and fluid constitutive law, where the fluid dynamics of the actuation solenoid valve, actuation piston, passages, and orifices, that influence the engine valve profile, are considered in detail. Second, to have an LPV control-oriented model, the order of nonlinear model is reduced and subsequently transformed into an LPV model with minimal deviation by carefully considering the system nonlinearities, time delay, and time-varying parameters. Calibration and validation experiments for both nonlinear and LPV models were performed on the test bench under different operational conditions. The key time-varying parameters, the time constant of the actuation piston top pressure and the discharge coefficient, are highly nonlinear as functions of temperature-sensitive fluid viscosity and are determined using the test data through the least-squares optimization. With the identified and calibrated model parameters, simulation results of both nonlinear and LPV models are in good agreement with the experimental ones under different operational conditions.

Modeling of Magnetic Field and Transients in a Novel Permanent Magnet Valve Actuator

“…Contrary to the electro-hydraulic valve actuators, our construction does not need the hydraulic block and, despite this, it achieves low switching times (5 ms). The obtained values of the runner stroke times are similar to those obtained in [2] and [3]. The presented paper is a substantial extended version of the conference ISEF 2019 presentation [12], and gives more details about the described actuator design.…”

“…There are two main ways to do this. The first one is the use of hydraulic or electro-hydraulic actuators [2][3][4], and the second one can be the application of fully electromagnetic ones [5][6][7][8][9][10][11].…”

Review of Advancement in Variable Valve Actuation of Internal Combustion Engines

“…For the EHVVA system by Lou et al [84], Li et al [81] studied the profile tracking problem without the need for complicated control scheme because of the inherent robust nature of its lift control and seating-velocity control. However, the valve timing and profile area controls are still challenging because of the nonlinear and time-varying nature of the hydraulic system, including nonlinear flow dynamics and temperature-sensitive fluid viscosity [83,102]. A receding horizon linear-quadratic tracking (LQT) controller was designed along with a Kalman optimal state estimation, which was proven to be effective through both steady-state and transient validations.…”

“…• Gongda Power developed the Gongda-VVA-2 (GD-VVA-2). It includes one digital three-way pilot valve, one digital three-way main valve, an actuator with one lift-control sleeve, two-step seating control, open-loop two-step lift control, and no position sensor [81][82][83][84]. The two-step lift control provides robust and accurate position control, which is delineated mechanically by the lift-control sleeve, without the need for an expensive and unreliable position sensor.…”

Modeling and Analysis of an Electromagnetic Fully Variable Valve Train with a Magnetorheological Buffer

“…The electro-hydraulic VVTs, designed by Lou Z. [17,18] have a build-in soft-landing feature including hydraulic valves and snubbers for seating velocity control without complex control strategy. In some hydraulic valves research by Huang Y [19], double pulse signals of release solenoid valve are designed to eliminate the impacts of electrohydraulic exhaust valve seating.…”