The effect on the stability of the pneumatic valve throttling flow factors have those?

throttling are the factors affecting the stability of pneumatic valve flow?
no matter what form of throttle opening, its flow characteristic are satisfy orifice flow formula, namely q = KA T Δ PM. Throttling pneumatic valve in the flow cross-sectional area A T throttling mouth after setting, often asked by the flow of A T q remain stable, make the speed of the actuator stability. However, through the throttling pneumatic valve flow is stable, actually also is associated with the following factors.
(1) the pressure difference between the before and after pneumatic valve throttle Δ p. When A T must, as the change of Δ p, through pneumatic valve flow q also follow change, namely the flow instability. Hydraulic system load is often not a fixed value, load change, components of pressure change, and actuators connected to the throttle pressure difference before and after pneumatic valve Δ p change namely, traffic has changed. Thin wall orifice m minimum value, therefore, the influence of load change on thin-wall hole flow has the smallest.
(2) the temperature of the oil. Oil temperature change caused by oil viscosity changes, small hole flow general formula of the K value is changed, so that the flow rate change. Obviously, the longer the orifice, the greater the impact; Thin blade hole length is short, the least sensitive to changes in temperature.
(3) and minimum stable flow throttling mouth jam. Experiment shows that the differential pressure, oil under the condition of invariable factors such as viscosity, mild when the pneumatic valve throttle opening is very small, traffic will be unstable and even the phenomenon of blocks the flow, this phenomenon is called congestion. Obstruction of the main causes are: the throttling mouth high-speed flow produce local high temperature, oil oxidation generated colloid and precipitation, and even cause carbon burning ashes in the oil, the oil and products of the original impurities, the throttling mouth gradually formed on the surface of the adhesive layer, it is constantly accumulation and high speed flow hedge, traffic will constantly change, attached layer avenues appear to flow throttling mouth.
obstruction caused by uneven system speed of executive element, thus throttling pneumatic valve can have a normal job, Means no cut-out and the flow rate is not more than % of the allowable value of minimum flow, known as the minimum stable flow throttling pneumatic valve. In practice, the measures to prevent throttling pneumatic valve block has the following two.
(1) the oil to precision filter. Practice has proved that ~ mu m filtering precision can significantly improve the blocking phenomenon. To remove the iron pollution, using magnetic filter effect is better.
(2) at the ends of the pneumatic valve throttle pressure difference to be appropriate. Differential pressure big, throttling mouth energy loss is big, high temperature; The same flow rate, pressure difference big corresponding flow area is small, easy cause blockage. When the design generally take differential Δ p =. ~。 MPa。