Abstract: Aiming at the problem of the low qualification rate of a certain type of hydraulic door closer manufactured by the enterprise,the damping force of the plunger during the operation of the door closer was studied by theoretical calculation, simulation analysis and experimental testing.Firstly, based on the theory of hydraulic fluid mechanics, a mathematical model of the damping force was established when the plunger of the door closer was at different positions, and the relationship curve between the pressure and the speed of the plunger rack under different conditions was obtained by the auxiliary calculation of MATLAB,and the damping force of the door closer was analyzed theoretically. Then based on the Fluent,the internal flow channel model of the door closer was established,and the flow channel pressure distribution through flow field simulation was obtained. Finally, through the door closer bench test, the door closing force and the door closing time in different positions were tested after the door closer was installed, and the model was verified with the simulation results. The research results show that the error between the theoretical closing force and the actual closing force is 2.6 N~3.5 N, and the established mathematical model of the damping force of the door closer is accurate and reliable, which can be used as the basis for the structural optimization of the door closer.

Key words:  hydraulic door closer; hydraulic damping element; damping characteristic; mathematical model; flow field simulation