Priority valve, hydraulic system and loader

Abstract

The invention relates to the field of loaders, and discloses a priority valve, a hydraulic system and a loader. The priority valve comprises a valve body and an auxiliary oil cylinder, the auxiliary oil cylinder comprises a cylinder body and a piston rod, the cylinder body is connected to the priority valve body, a rod cavity of the cylinder body is communicated with a spring cavity of the priority valve body, the reset spring abuts against the position between the second end of the priority valve element and the piston rod, a control oil port K is formed in the cylinder body, and the control oil port K is communicated with a rodless cavity of the cylinder body. By additionally arranging the auxiliary oil cylinder, the piston rod can further compress the reset spring by introducing oil into the control oil port K, so that the back pressure of the oil inlet P is increased to adapt to individual working conditions, and the low back pressure of the oil inlet P can be kept under other working conditions to reduce throttling loss and realize two-stage control of the priority valve. The hydraulic system comprises the priority valve, a pilot pump is omitted, cost is saved, and the problems that when the hydraulic system works on the flat ground in a linear floating mode, pilot pressure is low due to insufficient main pressure, and floating action cannot be achieved are solved.

Description

technical field [0001] The invention relates to the technical field of loaders, in particular to a priority valve, a hydraulic system and a loader. Background technique [0002] The current pilot-controlled loaders, the pilot-controlled hydraulic system and the main working hydraulic system, are generally supplied with oil by different hydraulic pumps. like figure 1 As shown, the pilot control system is generally composed of a pilot pump 1', a pilot oil source valve 2', a pilot filter 3', a pilot handle 4' and other components, and the cost is relatively high. [0003] The cost reduction scheme on the pilot control hydraulic system, the current existing schemes, such as figure 2 As shown in the figure, the pilot pump is generally removed, and the scheme of adding high pressure oil in the main oil circuit with a pressure reducing valve is adopted, and the purpose of cost reduction is achieved by saving a pilot pump. However, this scheme has great defects and cannot be ada...

AI Technical Summary

Problems solved by technology

The whole machine cannot stably complete the linear floating leveling action

[0008] If other actions are performed first to fill the accumulator with pressure, and then float, although the action can be completed, but it is not coherent. Since the volume of the pilot accumulator is generally small, the floating action cannot be performed after leakage.

[0009] If the spring back pressure of the priority valve is adjusted so that the P port of the pilot pump always has a back pressure value above 25Bar, although it can ensure the above working conditions, but the steering pump will always have a large flow rate of 25Bar because it is a gear pump. , energy consumption, heat generation will be quite serious

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