Flow control system and control method for array switch valve

Abstract

The invention relates to a flow control system and a control method for an array type on-off valve. The three-position four-way reversing valve and two groups of parallel array type on-off valves are used to control the cylinder, which reduces the need for the original single-chamber separate control of the hydraulic cylinder. The complexity of inflow-outflow control simplifies the control algorithm; by setting the flow switching threshold, each group of parallel array on-off valves can adjust the large flow through the multi-valve composite control signal based on the combination of pulse code-pulse-width-pulse frequency modulation. The single-valve composite control signal combined with pulse width-pulse frequency modulation is used to control the deviation of the fine flow of a single on-off valve; the size of the selected single-on-off valve control signal is determined by the optimization function based on the flow deviation, the change of the pressure difference at the valve port, and the number of valve opening and closing. Further decision; in addition, through the switch optimization distribution strategy, the number of times of each valve switching is evenly distributed, which minimizes the fatigue and wear of the digital valve control system due to the continuous switching of the switching valve, and further improves its service life.

Description

technical field [0001] The invention relates to the field of hydraulic control systems, in particular to a flow control system and control method for array switch valves. Background technique [0002] High-performance valves are an important part of most hydraulic servo systems. As a key control element of electro-hydraulic servo systems, servo proportional valves have been widely used in the field of electro-hydraulic servo control due to their superior precision control performance. However, their existence Sensitivity to impurities, high power consumption, high cost, and low reliability. With the combined development of hydraulic technology and computer technology, the electro-hydraulic digital control system came into being. Due to the characteristics of high efficiency, high economy and high reliability of the digital hydraulic valve, it is considered to be a kind of valve that has certain competition with the traditional proportional servo valve. power alternatives. ...

AI Technical Summary

Problems solved by technology

[0006] (1) The existing on-off valve control cylinder system is difficult to balance control accuracy, hardware cost, and control algorithm cost at the same time

In the existing system, two parallel on-off valves are configured in one chamber of the hydraulic cylinder, one is connected to the pump source, the other is connected to the oil tank, and the other chamber is the same. When controlling the cylinder, the two on-off valves are in the high-frequency switching state. Reasonably distribute the duty ratio of each switch valve, so that the flow flowing into or out of the single chamber of the hydraulic cylinder is finer, the flow resolution is higher, and the control accuracy is better. However, under this configuration condition, due to the introduction of cross flow, and The on-off valve is in a high-frequency on-off state, which makes the calculation process of the target flow into or out of the cylinder more complicated. At the same time, the requirements for the coordinated control algorithm of the two-way parallel on-off valve are also high, and it is difficult to take care of it at the same time.

[0007] (2) When the pulse width modulation signal is used to control the small flow rate of the on-off valve, there are problems of flow nonlinearity, narrow adjustable range of duty ratio and low operating frequency, which limit the resolution of the on-off valve flow control

Based on the above factors, there is a problem of response lag control or nonlinear error when the on-off valve is used for flow control, which leads to unsatisfactory control of the flow deviation and ultimately affects the tracking control performance of the cylinder.

[0008] (3) Due to the continuous switching of the on-off valves, it is easy to cause only part of the on-off valves to participate in the work during the flow control process, and the rest of the on-off valves do not work, resulting in a large difference in the degree of wear of the on-off valves

That is, when multiple on-off valves participate in flow regulation, if the flow in or out of the hydraulic cylinder is required to increase or decrease, the traditional control method is to increase or decrease the participation of new on-off valves on the basis of the original on-off valves involved in the work, resulting in In the process of flow regulation, some on-off valves are less likely to be used, which makes the difference between the wear of each on-off valve spool and the remaining service life too large. If it cannot be disassembled and replaced in time, it will easily affect the performance of the valve control system for a long time. Negative Effects

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