Optimization study on valve seating characteristics of hydraulic variable valve system

Variable valve technologies, as an advanced category aimed at enhancing internal combustion engine thermal efficiency and emission performance, are highly favored within the automotive industry. This paper proposes a hydraulic variable valve system that can achieve continuous variation in valve phase and lift while maintaining a simple structure. Pre-tests show that at higher engine speeds, the valve seating characteristics are not stable enough. This study believes that in addition to considering the lower seating velocity, the valve seating characteristics also needs to take into account the timeliness of the valve seating and the permissible requirements of hydraulic oil pressure. In order to improve the valve seating performance of the system at higher speed, we first built a simulation model, analyzed the valve seating influencing factors, and then established an optimization model of valve seating characteristics, optimized the parameters of the buffer mechanism and carried out verification tests using a physical platform. The results show that under the premise of meeting the allowable oil pressure, the maximum valve seating velocity is decreased from by 60% from 1.33 m/s to 0.52 m/s, and the seating phase delay is only 3.3°, realizing the smooth seating and effectively increases the applicable speed of the hydraulic variable valve system by 28.5% to above 4500 r/min.