Design and Analysis of a Fully Variable Valve Actuation System

Abstract

With the problem of environmental pollution and energy shortage becoming more and more serious, the fuel efficiency of automobile engines has attracted much attention, and variable valve technology is one of the important technologies to solve this problem. A novel fully variable valve actuation (FVVA) system based on a brushless direct current motor (BLDCM) is designed to achieve fully variable valve adjustment. The system uses a crank-moving guide rod mechanism to convert the rotary motion of the BLDCM into the linear motion of the valve. The fully variable valve system can realize real-time continuous adjustment of valve operating parameters through the motion control of BLDCM, including variable valve timing, variable valve opening duration, and variable lift. A BLDCM and a transmission mechanism for the FVVA system is designed in this paper. In order to better analyze the performance of the system, a dynamic model is established. Then, a three closed-loop control method is adopted to realize position control of the valve. Finally, a complete system model is established to verify the theory conclusions. The results show that the system can realize fully variable valve adjustment.

Comparative study by numerical simulation of two methods for automatic flow control in centrifugal pumps

“…The outermost loop is for linear position control of the system, and receives feedback from a linear position sensor. For fast response and safe operation, each control system loop must be precisely designed [24], [25].…”

“…Also observed was the dynamic response of the three variables from the cascade control of the actuator: current (internal loop), speed (medium loop), and position (external loop). The response time was lower the more internal the control loop was, which is required for the adequate performance of the cascade control [24].…”