A Negative Flow System of Excavator with Load Sensitivity

Abstract

The invention discloses an excavator negative flow system sensitive to load. The system comprises a hydraulic proportional direction valve, a servo piston, an engine, a variable pump, a metering pump, a first overflow valve, opened-center six way proportional directional valves, cylinders, a plurality of shuttle valves, a solenoid directional valve, a constant difference overflow valve, a throttle, a second overflow valve and the like. The constant difference overflow valve and the shuttle valves are arranged in front of the throttle, the shuttle valves are utilized to obtain the maximum pressure of load and guide to the constant difference overflow valve to control a hydraulic fluid port, and the displacement of the variable pump is maximized before the pressure required to overcome the load is provided at the variable pump outlet, meanwhile, the hydraulic oil return port of the variable pump is sealed, and the pressure required to overcome the load is allowed to be provided at the variable pump outlet rapidly. By the aid of the excavator negative flow system, energy loss of a hydraulic pump can be reduced when a main control valve is in the neutral position, the throttle has no throttling consumption before the pressure required to overcome the load is provided, and energy loss of a hydraulic system is reduced.

Description

technical field [0001] The invention relates to a hydraulic control system characterized by electro-hydraulic control technology, in particular to an excavator negative flow system with load sensitivity. Background technique [0002] With the increasingly serious problems of energy shortage and environmental pollution worldwide, it is of great practical significance to study the energy saving of construction machinery. Hydraulic excavator is a kind of construction machinery with relatively high power, but its total utilization rate of energy is low. Energy saving and emission reduction of hydraulic excavators have always been the goal pursued by the industry. [0003] The current mainstream excavators still use the multi-way valve as the main control valve. With the development of hydraulic energy-saving technology, the hydraulic system of the excavator has developed from the direct control of the displacement of the hydraulic pump by the pilot pressure of the joystick in ...

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Problems solved by technology

[0005] In view of this, the present invention aims at the deficiencies in the prior art, and its main purpose is to provide a load-sensitive excavator negative flow system, which can effectively solve the problem that the speed regulation characteristic of the traditional hydraulic excavator negative flow system is affected by load pressure and Insufficient effect of hydraulic pump flow rate, while reducing the throttling loss of the throttle port of the hydraulic control valve

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