Hydraulic system for controlling amplitude variation of crane boom, control method and crane

Abstract

The invention discloses a hydraulic system for controlling amplitude variation of a crane boom. The hydraulic system comprises an amplitude-variable oil cylinder, a hydraulic pump, a main valve and an oil tank; a rodless cavity of the amplitude-variable oil cylinder is connected with the hydraulic pump through the main valve; a rod cavity of the amplitude-variable oil cylinder is connected with the oil tank; and a first pressure reducing valve is provided between the main valve and the rodless cavity to make the pressure of the oil flowing through the main valve constant during amplitude variation of a descending arm of the amplitude-variable oil cylinder. The invention also discloses a control method based on the hydraulic system disclosed by the invention, and a crane which uses the hydraulic system disclosed by the invention. The first pressure reducing valve is arranged between the main valve and the rodless cavity of the amplitude-variable oil cylinder, and the oil pressure of the oil flowing through the main valve constant is kept constant by the first pressure reducing valve, so the sum of the lowering speed of the amplitude-variable oil cylinder is related to the opening degree of a valve port of the main valve, and is not affected by the load changes; and during amplitude-variable operation of the descending arm of the crane boom, the hydraulic system is not affected by the increasing load, the stable falling speed is maintained and the security is high.

Description

technical field [0001] The invention relates to the field of hydraulic control of jib amplitude, in particular to a hydraulic system for controlling jib amplitude, a control method and a crane using the hydraulic system. Background technique [0002] In the jib luffing operation of construction machinery, such as in truck cranes, the luffing cylinder is usually used to drive the jib luffing operation. During the jib luffing operation, there are generally two methods for lowering the luffing cylinder. One It is a hydraulically driven downward method based on proportional valves and balance valves, that is, it is necessary to supply pressure oil to the rod cavity of the luffing cylinder. Consider matching issues caused by compensating for load variations, which are difficult to implement and can easily cause reliability issues. In addition, during the lowering of the luffing cylinder, there is an overrunning load, that is, an external load whose direction and the direction of...

AI Technical Summary

Problems solved by technology

At this time, the adjustment of the lowering speed and the size of the orifice of the balance valve used for speed regulation are poor in linearity, and good speed regulation characteristics cannot be achieved. The operator must pay a lot of attention, and it is likely to cause regulation. Arm drop accident caused by untimely speed

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