Created on:2021-05-11 10:33

Electro hydraulic digital hydraulic pump

Electro hydraulic digital hydraulic pump

As we all know, the hydraulic pump with electro-hydraulic servo or electro-hydraulic proportional control is of great significance to realize the automation and energy saving of hydraulic system control. However, if this kind of pump is controlled by computer, it needs a digital to analog converter (DAC). The electrical interface is complex, and it is sensitive to oil pollution, so the requirements of manufacture, use and maintenance are high. And the digital control of the hydraulic pump (referred to as the digital hydraulic pump) can overcome the above defects, now briefly as follows.

The digital control hydraulic pump is also composed of the main body and the variable mechanism, in which the variable mechanism is controlled and adjusted by the electro-hydraulic digital control valve. Figure o shows an axial piston variable displacement pump controlled by a slide valve type digital valve. Its working principle is: the speed of the actuator is converted into pulse signal, the stepping motor is controlled by the microcomputer, the rotary motion of the stepping motor is converted into linear motion by the mechanical converter, and the opening and direction of the slide valve digital valve are controlled, so as to control the pressure and direction into the variable cylinder, so as to realize the control of the inclined angle of the swash plate of the piston pump, and obtain the required flow and the pressure of the pump The force automatically follows the load. Therefore, it is a kind of Self-adaptive Hydraulic Pump with neither excess pressure nor excess flow. If the main oil circuit of the pump is cut off by the reversing valve or connected to the oil tank, the swash plate of the pump is controlled by the microcomputer at the zero deflection angle position; if the system has excessive load, it can be protected by the safety valve.

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Because the pressure parameters of the hydraulic system change with the load, the flow data can be input into the microcomputer in the form of software for the main equipment with constant working conditions, such as hydraulic press. When the equipment is working, the characteristic curve corresponding to the load pressure and flow can be obtained completely, and the purpose of adjusting and modifying the characteristic curve can be achieved by modifying the software. For the main engine equipment with random working conditions, such as hydraulic excavator, the computer can obtain the best energy-saving system which can meet the requirements of load and fuel economy according to the feedback information of pressure sensor, flow sensor and speed sensor on the engine.

In a word, the electro-hydraulic digital pump is a hydraulic pump of mechatronics and has the following characteristics.

① It can form a power adaptive system without pressure loss and flow loss, improve system efficiency and realize energy saving.

② It is easy to realize the computer control of the pump, especially the microcomputer control, so some manufacturers call this kind of pump microcomputer controlled variable displacement pump.

③ It can directly interface with the computer (without DAC), and easily obtain the required control characteristics by changing the software. It can replace the existing variable displacement pump, with strong adaptability to working conditions and convenient use and maintenance.

④ It can form a closed-loop system with good response characteristics, high repetition accuracy and wide adjustment range.

⑤ Compared with servo pump, it has strong anti pollution ability and high reliability.

At present, there are few commercial products of electro-hydraulic digital hydraulic pump, so users can obtain the digital pump by adding a stepping motor to the variable mechanism of the existing variable pump.

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