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

Abstract

Electromagnetic fully variable valve train (EMVT) technology promises to improve the fuel economy and optimize the engine performance. A novel EMVT equipped with a magnetorheological buffer (EMVT with MR buffer) is proposed to suppress the valve seating impact in this paper. The magnetorheological buffer can adjust the damping characteristics of the whole system in the seating process. Valve precise motion control and better seating performance can be achieved through the coordinated control of electromagnetic linear actuator (EMLA) and MR buffer. For better analysis of system performance, establishing an accurate system dynamic model is the basis of the coordinated control system. A high-order nonlinear precise model integrating dynamics, electromagnetism, and fluid mechanic was established. Then, the Jacobi linearization model is carried out at the equilibrium seating point to build a control-oriented linearized model. The correctness and accuracy of the linearized model is verified. Experiments and simulations show that the valve precise motion can be well controlled to achieve fully variable actuation. And the valve soft landing can be completed under collaborative control.

Optimization design of a fully variable valve system based on Nelder-Mead algorithm

“…The fully variable valve system works as follows 11 : when the valve opens, the current is applied to the EMLA coil generating an axial electromagnetic force to drive the valve. When the valve closes, the MR buffer will be turned on before the valve is seated.…”

“…Simulation and experiment results showed that valve seating characteristics become stable and soft when the engine is at the speed of 5000 r/min. Guo et al 10 and Zhu et al 11 have studied a fully variable valve system that uses the magnetorheological buffer (MR buffer) to realize seat cushioning, which could minimize the seating velocity and rebound height of the valve. In the system, the electromagnetic linear actuator (EMLA) is a moving coil linear motor that the axial driving force is generated by the current-carrying coil in the permanent magnetic field to drive the valve moving.…”

Research on Aluminum Honeycomb Buffer Device for Soft Landing on the Lunar Surface

“…Currently, the buffers used in research and development mainly include aluminum honeycomb buffers, hydraulic buffers, mechanical buffers, magnetorheological fluid buffers, and metal rubber buffers. [22][23][24][25][26][27][28] The aluminum honeycomb buffer is the most used and most mature buffer among the successfully launched landers. The buffer has low mass, good energy absorption effect, stable operation, adjustable buffer stroke, and low dependence on the environment.…”