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Hydraulic Lift Control Method
Aug 15, 2017

From the point of view of control theory, the elevator hydraulic system is a typical nonlinear, variable load and variable parameter system, and the riding comfort puts forward higher requirements for its position and speed control accuracy index. So far, a variety of elevator hydraulic control systems have been developed. The control mode can be divided into 4 types: switch control, volume speed control, proportional control and compound control.

(1) switch control

The elevator switch control mode of hydraulic control system of hydraulic elevator are mostly found in the early, dual speed hydraulic lift as the earliest, is the use of switch input (mechanical or electric) to control system in high speed switching operation and a flat layer between the two conditions of the dock.

(2) volume speed control;

Hydraulic elevator speed control system mostly flow volume loop control, the actual flow sensor through the main circuit in the comparison, the optimum flow curve set with the circuit, to control the variable pump or motor. Because of the flow loop, operation performance of Peng Wen volume speed control of hydraulic elevator well, load stiffness, hydraulic system volume control scheme for the pump output power and the power required to lift up roughly equal, so compared with the throttle speed control scheme with high efficiency, energy loss caused by heat is small.

(3) proportional control

Hydraulic elevator proportional control system is the most widely used hydraulic elevator system. It was developed in the early 80s with the development of electro-hydraulic proportional technology. These systems make use of flow displacement force feedback and flow electric feedback to form feedback loop, and restrain the influence of load and nonlinear factors on system performance. At the same time, the ideal flow curve is stored in the circuit to control the change of the actual flow, plus the feedback loop of the high frequency response, so the dynamic performance and the running stability of the system are very good.

(4) compound control

The hydraulic elevator compound control system mainly refers to the system that fuses many kinds of control modes. Currently, energy recovery systems are common. Energy recovery hydraulic elevator can thoroughly solve the problem of temperature rise of hydraulic system, the control system of elevator uplink part by volume speed control or electro-hydraulic proportional control, and control the elevator down part has a unique structure, it can be decreased in the course of the car's potential energy is converted into electrical energy by a hydraulic circuit.

However, this kind of control system is higher in cost and has not formed a big market. But as an energy-saving control system, it has a good application prospect. Some foreign research institutions are investing a lot of money to develop this kind of system.





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