Speed regulation and control system for lifting mechanism of tower crane

Abstract

The invention discloses a speed regulation and control system for a lifting mechanism of a tower crane. The lifting mechanism of the tower crane is controlled by a PLC through a frequency converter; the switching value of each shift during the ascending and descending of the tower crane is input into the PLC; the output of the PLC is connected with the frequency converter; the output of the frequency converter is connected with an ascending motor; and the PLC program design completes the logic operation of a given signal and a peripheral signal of the ascending frequency converter, the control of a brake, the logic judgment and alarm of various fault signals. An electrical towage system of the tower crane is subjected to technical transformation by using advanced PLC frequency conversion and speed regulation technology, so that the lifting mechanism of the crane realizes stable operation, enhances the operating efficiency, improves overload operation, eliminates starting impact and braking impact, reduces electric maintenance, reduces power consumption, and improves power factors. Simultaneously, the lifting mechanism has the advantages of over-current protection, over-voltage protection, under-voltage protection and input phase-lacking protection, and over-temperature protection, overload protection and over-speed protection of the frequency converter, overheat protection of a brake unit, an I / O fault protection, and motor fault protection and the like.

Description

1. Technical field [0001] The invention relates to the speed regulation control of a hoisting mechanism of a tower crane. 2. Background technology [0002] The hoisting mechanism is the most important transmission mechanism of the tower crane, and its speed regulation method directly affects the performance of the whole machine. At present, the traditional speed regulation method cannot realize low speed under heavy load and high speed under light load, and the speed regulation range is small. There are three principles for selecting the speed regulation mode of the hoisting mechanism: firstly, it should be stable and have small impact; secondly, it should be economical and reliable, in line with national conditions; thirdly, it should be easy to maintain. Commonly used traditional tower crane speed regulation methods are as follows: one is winding asynchronous motor rotor series resistance speed regulation, thyristor stator voltage regulation and cascade speed regulation; ...

AI Technical Summary

Problems solved by technology

Their common features are poor transmission performance, poor reliability, increased energy consumption, and increased maintenance costs, and they all use a single brake.

The advantages of single brake are simple structure, convenient installation, debugging and maintenance; its disadvantage is also the main fatal point, that is, when the brake fails, the motor shaft or reducer shaft is damaged, the brake friction plate is worn, etc. After the brake device fails, There are no other protective measures to brake the lifting device, and accidents caused by this reason are not uncommon

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