A terminal release type torque limiting valve and a hydraulic control torque limiting system equipped with the valve

Abstract

The invention discloses a terminal removing type moment limiting valve and a hydraulic-control moment limiting system with the same. A moment limiting unloading valve and a moment limiting control valve are included. A control oil opening of the moment limiting unloading valve is communicated with a control oil opening of the moment limiting control valve. A first oil opening of the moment limiting unloading valve and a second oil opening of the moment limiting unloading valve are communicated with a first amplitude variation oil cylinder through single-way balance valves. A third oil opening of the moment limiting unloading valve and a fourth oil opening of the moment limiting unloading valve are communicated with a second amplitude variation oil cylinder through first double-way balance valves. A fifth oil opening of the moment limiting unloading valve is communicated with a telescopic oil cylinder through a second double-way balance valve. A first oil opening of the moment limiting control valve is communicated with a rodless cavity of the first amplitude variation oil cylinder. A second oil opening of the moment limiting control valve is communicated with a cavity with a rod of the first amplitude variation oil cylinder. The terminal removing type moment limiting valve and the hydraulic-control moment limiting system with the same have the advantages that a moment limiting unloading part can limit five actions, five groups of single-way valves and a hydraulic-control single-way valve form a main oil way together, flow capacity is high, oil ways are independent, and interference is avoided.

Description

technical field [0001] The invention relates to a terminal release type torque limiting valve and a hydraulic control torque limiting system provided with the valve, belonging to the technical field of truck-mounted cranes. Background technique [0002] In recent years, with the development of market and technology, the lifting capacity of truck-mounted cranes has been continuously improved, and the application of knuckle-arm cranes in our country is increasing day by day, and the requirements for their operation safety are also increasing. The function of the torque limiting system is to limit the operating torque and play the role of safety protection. Therefore, the moment limiting system, as the main safety protection system of the truck-mounted crane, has gradually become the research focus of the truck-mounted crane. [0003] In the prior art, a lot of explanations have been made on the electro-hydraulic control torque limiting device of cranes, but this kind of torqu...

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Problems solved by technology

[0003] In the prior art, a lot of explanations have been made on the electro-hydraulic control torque limiting device of cranes, but this type of torque limiting method has problems such as complex system, large number of components, high cost and low reliability

In order to effectively solve this kind of problem, the existing patent proposes a hydraulically controlled torque limiting system for a knuckle boom truck-mounted crane. The torque limiting valve can only limit three dangerous actions, and it needs to cooperate with the secondary pressure limiting plug-in of the directional control valve to control it. The first luffing lifting, the first luffing lowering, the second luffing lifting, telescopic extension four dangerous actions, the torque limiting system is complicated, and the moment limiting unloading part and the moment limiting control part are integrated structure, for The straight-arm truck-mounted cranes and folding-arm truck-mounted cranes in the truck-mounted cranes require different numbers of dangerous actions to be restricted (three dangerous actions are required for straight-arm truck-mounted cranes, and five dangerous actions are required for folding-arm truck-mounted cranes), This type of valve cannot meet the torque limit requirements of truck-mounted cranes with different numbers of dangerous actions at the same time; in addition, the torque limit valve has the feature that the force limit state can be forcibly released through the retraction of the telescopic cylinder, which provides users with the possibility of overload operation. Possibly, it is not conducive to the safety protection of the crane; finally, the torque limiting valve has the situation that the pilot valve of the unloading valve is inconsistent with the main valve of the unloading valve. In the middle position, the pilot valve of the unloading valve is still in the unloading state, the main valve of the unloading valve returns to the closed state under the action of the spring force due to the cut-off of the pressure oil circuit, and the unloading main oil circuit is still in the non-unloading state, resulting in the force limit of the crane. next action

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