Hydraulic system, pressure control method of hydraulic system, and engineering machine

Abstract

The invention discloses a hydraulic system, a pressure control method of the hydraulic system, and an engineering machine. The hydraulic system comprises an electronically controlled variable displacement pump, a pressure detector and a controller. The pressure detector is used for detecting pressure of an outlet of the electronically controlled variable displacement pump. The controller is connected with the electronically controlled variable displacement pump and the pressure detector and is used for controlling currents of the electronically controlled variable displacement pump when the pressure of the outlet cannot reach the preset pressure so as to change the displacement and lead the pressure of the outlet to reach the preset pressure. By adopting the hydraulic system and the pressure control method of the hydraulic system, system power can be saved, impact to the system is avoided, meanwhile the pressure of the system is kept constant, and no additional production cost needs to be added.

Description

technical field [0001] The invention relates to a hydraulic system, in particular to a hydraulic system, a hydraulic system pressure control method and construction machinery including the hydraulic system. Background technique [0002] In many machines, it is necessary to keep the system pressure at a constant pressure, such as the clamping mechanism in the machine tool, the distribution hydraulic system in the pumping equipment, etc. Therefore, hydraulic drives are widely used in various machines. At present, there are usually the following methods to keep the system pressure of the hydraulic system constant: 1) keep the system pressure constant through the relief valve; 2) keep the system pressure constant through the accumulator and the quantitative pump; 3) through the constant pressure pump The pressure cut-off valve on the system is used to keep the system pressure constant. However, when the pressure is kept constant through the overflow of the relief valve, the pow...

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Problems solved by technology

However, in the case of maintaining a constant pressure through the overflow of the relief valve, the power loss of the system is relatively large. When the pressure holding time is long or the relief valve needs to operate frequently, it is generally seldom used due to the consideration of power saving.

For the situation where the pressure is kept constant through the pressure-holding circuit of the accumulator and the quantitative pump, although this method is widely used, it has a large impact on the system and may cause damage to the system

For the situation that the pressure is kept constant through the pressure cut-off valve, the pressure compensation mechanism of the pressure cut-off valve must be additionally added to the constant pressure pump, thus increasing the cost of the hydraulic system

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