A crane and its gravity fall control method and control system

Abstract

The invention discloses a gravity drop control method of a crane arm. The luffing system of the arm includes an oil cylinder connected with the arm, and a balance valve connected with the oil cylinder for controlling the expansion and contraction of the oil cylinder; The control method first obtains the actual falling speed of the boom; then compares the actual falling speed with the preset target falling speed of the boom, and if the former is greater than the latter, then reduce the opening of the balance valve; if the former is less than The latter, increase the opening of the balance valve; if the two are equal, keep the current state unchanged. With this method, in the process of falling where the rodless cavity pressure of the oil cylinder increases with the decrease of the boom angle, compared with the existing technology, the actual falling speed can be kept constant, and fluctuations can be avoided to affect the work of the boom stability. The invention also discloses a gravity drop control system of a crane boom corresponding to the above method, and a crane using the system.

Description

technical field [0001] The invention relates to the technical field of engineering machinery, in particular to a crane, a gravity drop control method, and a control system. Background technique [0002] Crane luffing means that under the action of the luffing cylinder, the boom is driven to do the drop or lift movement, so as to realize the change of the boom angle. The luffing action is mainly composed of a boom, a turntable, an oil cylinder, a balance valve, and balance valve control components. Under the action of the oil cylinder, the boom drives the boom to rotate around the rear hinge point of the turntable, thereby realizing the rise and fall of the luffing . [0003] At present, there are two control methods for crane luffing and falling: [0004] The first is the power drop control method. The opening control pressure of the balance valve is directly taken from the rod cavity, and the opening size of the balance valve is controlled by controlling the pressure and ...

AI Technical Summary

Problems solved by technology

[0012] It can be seen that when the opening of the balance valve is constant, the falling speed of the luffing cylinder depends only on the pressure of the rodless chamber of the luffing cylinder, and the pressure of the rodless chamber of the luffing cylinder increases with the decrease of the boom angle, so , the falling speed of the variable amplitude is getting faster and faster during the falling process, and the falling speed may be too high, resulting in poor comfort during the entire operation process, and it is difficult for the operator to maintain the variable amplitude falling speed within a small fluctuation range

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