Closed system of crane

Abstract

The invention discloses a closed system of a crane. The closed system comprises a closed system control main valve, an amplitude variation oil cylinder, a telescopic oil cylinder, a variable displacement motor and a closed pump. The closed system control main valve is connected with the amplitude variation oil cylinder through an amplitude variation control valve. The variable displacement motor and the telescopic oil cylinder are connected with the closed system control main valve. An opening A1 of the closed pump communicates with an opening PA of the closed system control main valve, and anopening B1 of the closed pump communicates with an opening PB of the closed system control main valve. The closed pump is connected with a solenoid valve Y1, and a temperature sensor is arranged between the closed pump and the closed system control main valve and connected with a controller. An oil make-up control valve set connected with an oil tank is arranged between the opening PA of the closed system control main valve and the opening B1 of the closed pump. The oil tank is connected with an oil make-up pump, and the oil make-up pump is connected with a solenoid valve Y3 and is connectedwith the opening PA and the opening PB of the closed system control main valve. The heat radiation performance of the whole system is improved.

Description

technical field [0001] The invention relates to a crane closed system. Background technique [0002] The hydraulic system is generally divided into an open system and a closed system according to the circulation mode of the oil. Among them, the open system means that the hydraulic pump sucks oil from the oil tank, and the oil drives the hydraulic actuator after passing through various control valves, and the oil returns through the reversing valve. Return to the oil tank; while the closed system means that the oil inlet pipe of the hydraulic pump is directly connected to the oil return pipe of the actuator, and the working fluid is closed in the pipeline of the system. The actuator is generally a hydraulic motor. Domestic small-tonnage truck cranes usually adopt an open system with a reversing valve to realize the forward and reverse movement and braking requirements of the fulfillment mechanism, while medium and large-tonnage cranes mostly use a closed system, and the close...

AI Technical Summary

Problems solved by technology

[0007] First, when hoisting hoisting and luffing, the pilot oil is used to open the luffing control valve and then fall by its own weight. The luffing cannot absorb negative power, resulting in large heat generation of the luffing system and low energy saving. poor

[0008] Second, the closed system of the crane, the closed system has no flushing function, the heat dissipation performance of the whole system is poor, and the heat exchange performance is not good. After a few cycles of heavy-duty hoisting and landing, the temperature of the hoisting circuit can quickly reach 80 ℃ The above affects the operation of the system

[0009] Third, in the existing closed system, the pressure level of the main pump of the luffing and telescopic system is relatively high, which increases the performance requirements of the pump and the requirements of related components, which easily leads to high design costs

[0010] Fourth, in the existing closed system, oil replenishment is mainly carried out through quantitative pumps, and the oil replenishment pressure is constant and cannot be adjusted according to demand

In the actual operation process, some working conditions do not require too much oil replenishment, and the quantitative pump cannot be automatically controlled according to the working conditions

Images