Super-tonnage lifting extension and retraction system and control method for all-ground crane

Abstract

The invention discloses a super-tonnage lifting extension and retraction system and control method for an all-ground crane. The outlet pressure of a multi-path valve bank is compared with the outlet pressure of a pump through a super-tonnage lifting controller, a current value used for controlling an electric proportional overflow valve in a hydraulic source is output, and a pressure cut-off valveof a constant-pressure variable pump is changed, so that the outlet pressure of the constant-pressure variable pump and the outlet pressure of the multi-path valve blank are maintained at a constantpressure difference value. In this way, the super-tonnage lifting amplitude can be changed through the system and method, and an oil cylinder has good synchronicity and speed regulation performance when extending and retracing; prompting or automatic tensioning is achieved in use when the oil cylinder retracts, the speed can be automatically decreased when the oil cylinder approaches an upper deadpoint and a lower dead point, system impact is reduced, and the safety and stability of the system are improved; and the output flow is matched with the flow required by a load, the response speed ofthe system is ensured while the energy loss of the system is reduced, and the controllability of the system is improved.

Description

technical field [0001] The invention relates to the technical field of all-terrain cranes, in particular to a super-lifting and retracting system and a control method for all-terrain cranes. Background technique [0002] With the development of national construction, cranes are increasingly developing in the direction of large-scale. With the increase of the length of the boom of the crane, the deflection of the main boom in the luffing plane also increases, which makes the stress on the boom when hoisting heavy. The limitation of boom deflection and bearing capacity is greatly reduced. In order to improve the hoisting performance of the main boom due to the excessive disturbance of the main boom, currently super-large-tonnage cranes generally install a superlift device on the main boom to improve the effect of excessive deflection of the boom and affect its hoisting performance. Heavy performance condition. [0003] The super-lifting device in the prior art has a pair of...

AI Technical Summary

Problems solved by technology

[0007] For the above-mentioned super-lifting and retracting system, if the loads on both sides of the super-lifting are inconsistent, the flow rates entering the two luffing or retracting oil cylinders will also be different, resulting in poor synchronization of the oil cylinders during super-lifting, luffing and retracting. The super-lifting device is installed on the main arm At the end, out-of-synchronization will easily cause the load imbalance of the main arm, resulting in certain safety hazards; and in the above-mentioned system, the speed of the luffing action and the retracting action cannot be adjusted, and the micro-movement is poor, which makes the installation difficult.

At the same time, the energy saving performance of the system is not high. Regardless of the required flow rate of the system, the quantitative pump 100 always outputs a constant flow rate, and the system has relatively high energy loss.

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