Abstract:

The precise control of the fully variable valve electro-hydraulic system directly affects its physical effect．Through the four signal acquisition of the system, analysis of the time difference between signal characteristic positions, a complete system work cycle is divided into six characteristic stages. The four signals are the upstream pressure signal of hydraulic oil, the pressure signal of hydraulic oil inside the chamber, the signal of the additional valve lift and the driving current of the solenoid valve seperately. The six characteristic stages are the solenoid valve open delay, the delay caused by the solenoid valve mounting position and by the valve inertia, the stage of the hydraulic oil incharging and discharging and the solenoid valve close delay seperately.With the total delay of work cycle and the complete system work cycle, there are 8 characteristic time. By analyzing the influence of the control parameters on the length and the proportion of the characteristic time, the results obtained are as follows. The sensitivity of different characteristic time to control parameters is different, and when the characteristic time is not sensitive to the change of control parameters, it can not always be ignored. Reducing the total system delay, optimizing the control parameters of the system and reducing the additional lift are helpful to shorten the total work cycle and improve the response speed of the system. The study provides a theoretical and experimental basis for the precise control and optimization of the system.

Key words: characteristic time, fully variable valve electro-hydraulic system, proportion, work period division, diesel engine