Travelling control valve of crawler-type hydraulic travelling system and travelling system

Abstract

The invention discloses a travelling control valve of a crawler-type hydraulic travelling system and the travelling system. The travelling control valve comprises a flow dividing valve, shuttle valves, normal-off type pressure compensators and three-position four-way electromagnetic proportional reversing valves, wherein an quantitative pump output oil path is divided into two paths through the flow dividing valve, one path flows to a left travelling motor through the first three-position four-way electromagnetic proportional reversing valve, and the other path flows to a right travelling motor through the second three-position four-way electromagnetic proportional reversing valve; the pressure difference between the two ends of the first three-position four-way electromagnetic proportional reversing valve is determined by the first normal-off pressure compensator through the first shuttle valve; and the pressure difference between the two ends of the second three-position four-way electromagnetic proportional reversing valve is determined by the second normal-off pressure compensator through the second shuttle valve. According to the valve, the influence of two-side different loads on flow is effectively avoided, the synchronous precision of the motors on the two sides is improved, and differential driving is stabler and more flexible; the displacement of the two variable motors is controlled by the two-position three-way electromagnetic valves and pressure reducing valves correspondingly so as to achieve high-low-speed switching of vehicles.

Description

technical field [0001] The invention relates to a hydraulic travel system, in particular to a travel control valve and a travel system of a crawler-type hydraulic travel system, and belongs to the technical field of engineering machinery hydraulic control. Background technique [0002] Crawler-type walking system and tire-type walking system are the two most widely used walking systems in construction machinery. The crawler walking system has the following advantages: (1) The entire weight of the vehicle is the attached weight, so the traction adhesion performance is excellent; (2) Compared with the wheeled machinery of the same power, the crawler bearing surface is large and the grounding pressure is small. The sag depth on the top is small, so the rolling resistance is small, which is conducive to exerting a large traction force. [0003] Most of the crawler walking system adopts hydraulic transmission, because compared with mechanical transmission, hydraulic transmission...

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Problems solved by technology

[0005] The existing crawler hydraulic travel system mostly adopts variable pump system and quantitative pump system. The disadvantages of variable pump system are high cost, large volume, and inconvenient maintenance.

[0006] Although the existing quantitative pump system is simple in structure and low in cost, its disadvantages are as follows: ① Since the control valves of the two motors are on-off valves, and a quantitative pump is connected at the same time, the flow rates flowing into the two motors are different due to different loads , resulting in low synchronous driving accuracy of the walking system; ②When steering is required, because the reversing valve in the two motor control valves is an on-off valve, the flow into the motor cannot be adjusted, which will make the "differential speed" driving unstable; ③It cannot achieve high , low-speed switching

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