The thermodynamic study of the valve-controlled adjustable damping shock absorber is conducted in order to solve the problem of oil leakage caused by excessive temperature rise of shock absorber. In this paper, the temperature rise of the valve-controlled adjustable damping shock absorber is analyzed from the perspective of energy conservation. Combined with the theory of fluid mechanics, the damping heat model is established, and the heat dissipation model of the shock absorber is established based on heat convection, heat conduction and heat radiation. The corresponding thermal equilibrium equation is established on the basis of damping heat and heat dissipation. The effects of vibration velocity, outer diameter, thickness and length of reservoir cylinder, and wind velocity on its thermal performance have been investigated. Specifically, temperature after thermal equilibrium will grow with the increase of vibration velocity and thickness of reservoir cylinder and degrade with the increase of outer diameter, length of reservoir cylinder and wind velocity. The higher the balance temperature, the shorter time is required to arrive thermal equilibrium. The difference between the experimental and simulation values of oil temperature after thermal equilibrium was not more than 2 °C, which verified the correctness of the theoretical model, while the experimental value in the process of temperature rise lagged behind the simulation value, which was mainly caused by the cumulative error of step-by-step iteration and the mechanical hysteresis in the experiment. The conclusions obtained can provide some references for the design of shock absorbers.
Purpose The purpose of this paper is to study the influences of the oil film thickness between the friction pairs, the rotational speed of the active and passive friction disks and the inlet pressure of the lubricant on the transmission efficiency. Design/methodology/approach A mathematical model of transmission efficiency was established, and the efficiency of transmission was studied by means of numerical analysis. Findings The results demonstrate that the transmission efficiency decreases with the thickness of the oil film increases. When the thickness of oil film d = 0.1 mm, the relationship between transmission efficiency and transmission ratio is linear, that is, with the transmission ratio increases, the transmission efficiency also increases which does not change with the inlet pressure changes. However, when d = 0.1 mm, their relationship is non-linear; the efficiency increases first and then decreases as the transmission ratio increases, but decreases as the inlet pressure increases. Originality/value The authors obtained a rule is that increasing the rotational speed and reducing the inlet pressure of the lubricating oil can improve the transmission efficiency. This study can provide a theoretical basis for power transmission designing of hydro-viscous clutch.
CDC (Continuous Damping Control) shock absorber is the typical representative of the stepless valve-controlled type, which has the advantages of low cost and stable performance. Based on the throttling characteristics of the CDC valve, the damping force mathematical model of the CDC shock absorber is established. Through simulation analysis, the indicator characteristics and speed characteristics of the CDC shock absorber under different input currents and speeds are obtained. A CDC shock absorber testbed is built to study damping characteristics, and the results are compared with the simulation results. The results show that the indicator diagram obtained by simulation and experiment is smooth without distortion, and the speed characteristic diagram is smooth without a large mutation point. The experimental values of damping force are slightly larger than the simulation values. The relative error between the simulation data and the experimental data is basically less than 10% and the model has high accuracy. When the input current is the same, the damping force increases with the increase of piston rod speed. When the speed of the piston rod is the same, the damping force of the rebound and compression stroke decreases with the increase of input current.
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