| At present, about 100 million belt conveyors were used underground coal transportation, ground power plants, coal preparation plant and so on. For large belt in the installation process need to consider not only the proper power matching, rational layout, but also to solve the shock to the power network, belt and so on in the startup process, that is the common problem of soft startup in belt conveyor, because the soft startup is directly related to the working performance of the conveyor and safety in coal mines. So design a reasonable soft starter for conveyor has a great significance for coal mines'safety production and improving the working characteristics of the conveyor.There are three main methods commonly used in conveyor startup, they are the electric-control speed regulating startup, hydraulic coupling startup and hydro-viscous drive speed regulating startup. We find that hydro-viscous drive speed regulating startup is better than hydraulic coupling at high speed, and better than the electric-control speed regulating startup at low speed by comparing. In addition, it had many advantages compared to other speed regulating methods in manufacturing cost, heat dissipation, ease of maintenance and so on. However, our level of research in this area was at the initial stage, United States and Australia held the key technologies, and strictly blockaded the technologies.In this paper, with the support of some aspects, the hydro-viscous speed regulating device were studied and analyzed. Based on large amount of literature and actual research, the relevant theory was analyzed for the existing hydro-viscous speed regulating device. According to analyze the device's basic structure, the viscous friction mechanism was researched, and established the friction plate group dynamic equilibrium equation, at the same time, the transfer function with proportional pressure control was established on the basis of the calculation of the flow and the dynamic load balance equation of system. Using electro-hydraulic proportional pressure control system to control oil film thickness, and then control the output torque. By the computer simulation, the open-loop response and stability of electro-hydraulic proportional control system were analyzed, and found out the defects, and laid the formulation for choosing a strategy for the control system.For the shortage of open-loop control for the hydro-viscous speed regulating device, the closed-loop control strategy with PID control was designed. To set up the PID parameters and the system was simulated by computer. The results showed that the conventional PID control could not get a better speed regulating result. Then this paper used PID optimal control to set up the PID parameters, as a result, the conveyor achieved the desired starting result by simulating Harrision starting speed curve with the parameters which was optimized.Finally, this paper used hydro-viscous drive experiment bench to research the oil film pressure field between frictions and the torque transmission characteristics, the theoretical analysis was also verified. By the experiment, the optimized PID parameters were analyzed and tested. At the same time, the working oil temperature, load size and starting time impact on speed regulating starting was analyzed, and got the law of the factors. |
PDF Full Text Request