Flow distributors for construction machinery

Abstract

A flow distributor for construction machinery, a three-way flow distributor is connected between the T port and the P port, the three-way flow distributor has two working positions, its spring chamber is connected with a one-way damping valve, and the one-way damping The other end of the valve is connected to the downstream end of the LS port, and a second damping hole is set between the downstream end of the LS port and the upstream end; a second constant flow valve is connected between the downstream end of the LS port and the T port, and the upstream end of the LS port A first damping hole and a first constant flow valve are sequentially connected in series between the end and the T port. Its advantages are: the fixed damping hole and the variable damping hole form a half-bridge damping network, which ensures the stability of the LS pressure control signal; effectively ensures the smooth opening and closing of the valve stem of the flow distributor, realizes the stable diversion of the main valve and the flow distributor, and eliminates hydraulic pressure. The problem of system pressure fluctuation and mechanism jitter can improve the stability and safety of the main engine; in the quantitative load sensitive system, the flow can be distributed on demand, that is: "high pressure and small flow, low pressure and large flow".

Description

technical field [0001] The invention relates to a flow distributor. In particular, it relates to flow distributors for construction machinery quantitative load sensitive systems of construction machinery such as wheel loaders, cranes, and mini-excavators. Background technique [0002] Quantitative load sensing system is widely used in construction machinery such as loaders, truck cranes and small excavators because of its energy saving and low cost. The load-sensing multi-way reversing valve is the core component of this type of load-sensing system, and the quantitative load-sensing system needs to realize the distribution of actuator flow according to "demand", and the flow distributor is an indispensable component of this type of hydraulic control system. The flow distributor and the load-sensing multi-way valve are used to cooperate with each other to make the load-sensing system realize the function of "high pressure and small flow, low pressure and large flow", that is...

AI Technical Summary

Problems solved by technology

[0003] The three-way pressure compensator used in the quantitative load sensing system cannot eliminate and alleviate the pressure fluctuations of the actuators (hydraulic cylinders, hydraulic motors). The flow rate remains constant. When the actuator is not working, the hydraulic oil in the hydraulic system overflows through the three-way pressure compensator; when the handle is operated to make the main valve supply oil to the actuator, the hydraulic system quickly builds up pressure and reaches a higher level. When the actuator starts to work, the pressure difference between the upper and lower chambers of the three-way pressure compensator decreases instantly, and its valve stem closes quickly, so that the flow of the actuator suddenly increases and the pressure also increases. Then it increases; when the system pressure increases, the pressure at both ends of the three-way pressure compensator is sufficient to overcome the pressure of the return spring, the three-way pressure compensator opens, and the pressure at the pump port decreases again, and this cycle repeats, resulting in the failure of the actuator. Fluctuations in pressure and vibrations in the mechanical mechanism can easily lead to system instability and difficulty in control, resulting in safety accidents

In addition, pressure jitter, which is not allowed for construction machinery that requires high fretting performance, especially hoisting machinery

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