In this paper, an electromagnetic variable valve train with a magnetorheological buffer (EMVT with MR buffer) is proposed. This system is mainly composed of an electromagnetic linear actuator (EMLA) and a magnetorheological buffer (MR buffer). The valves of an internal combustion engine are driven by the EMLA directly to open and close, which can adjust the valve lift and phase angle of the engine. At the same time, MR buffer can reduce the seat velocity of the valve and realize the seat buffer of the electromagnetic variable valve. In this paper, the overall design scheme of the system is proposed and the structure design, finite element simulation of the EMLA, and the MR buffer are carried out. The electromagnetic force characteristics of the EMLA and buffer force of the MR buffer are measured, and the seat buffering performance is verified as well. Experiments and simulation results show that the electromagnetic force of the EMLA can reach 320.3 N when the maximum coil current is 40 A. When the current of the buffer coil is 2.5 A and the piston’s motion frequency is 5 Hz, the buffering force can reach 35 N. At the same time, a soft landing can be realized when the valve is seated.

Camless valvetrains have become a promising direction to improve the performance of internal combustion engines. In this paper, an electric load simulator is proposed to simulate and implement gas force on the exhaust valve for camless valvetrains under semi-physical conditions. According to test data, the 1D gas-dynamic model was established to get boundary conditions and initial values for 3D finite element simulation. The 3D finite element simulation model was solved to obtain the gas force characteristics of the exhaust valve for camless valvetrains. The electromagnetic actuator was designed according to the system scheme and performance requirements of the electric load simulator. The PID (Proportion Integration Differentiation) algorithm was designed to control the output force of the electric load simulator and reproduce the gas force characteristics of the exhaust valve. It was found that the output force of the electric load simulator could follow the variation of the target gas force and meet the performance requirements of the electric load simulator based on simulation results and experimental results.

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.