What role does the throttle valve play in the hydraulic system?
The main requirements of the hydraulic system for flow control valves are:
1. Larger flow adjustment range and uniform flow regulation.
2. When the pressure difference between the front and the rear of the valve changes, the flow change through the valve should be small to ensure the stability of the load movement.
3. The change in oil temperature has little effect on the flow through the valve.
4. The pressure loss when the liquid flows through the fully open valve is small.
5. When the valve port is closed, the leakage of the valve should be small.
It is conditional that the throttle valve is used to regulate the flow rate, that is, a link that receives the pressure signal of the throttle valve (a relief valve or a constant pressure variable pump connected in parallel) is required. Through this link, the flow change of the throttle valve is compensated.
In the hydraulic system, the throttle valve and the relief valve are connected in parallel to the outlet of the hydraulic pump to form a constant pressure oil source, so that the pressure at the pump outlet is constant.
The throttle valve is an element that can adjust the flow rate over a wide range to change the liquid resistance. Therefore, the flow rate into the hydraulic cylinder can be changed by adjusting the liquid resistance of the throttle valve, thereby adjusting the movement speed of the hydraulic cylinder.
If there is only a throttle valve in the circuit and there is no relief valve in parallel with it, the throttle valve will not be able to regulate the flow.
The hydraulic oil output from the hydraulic pump is all entered into the hydraulic cylinder through the throttle valve. Changing the throttle orifice size simply changes the pressure drop across the throttle. The orifice is small, the flow rate is fast; the orifice is large, the flow rate is slow, and the total flow rate is constant, so the movement speed of the hydraulic cylinder does not change.
Throttle throttle orifices usually have three basic forms: thin-walled orifices, elongated orifices, and thick-walled orifices, but regardless of the form of the orifice, the flow through the orifice and its differential pressure before and after Both can be expressed by the formula: q=KAΔpm, and the flow characteristics of the three throttle ports are as follows:
1. Influence of differential pressure on flow
When the pressure difference between the two ends of the throttle valve changes, the flow rate through it changes. In the three types of throttle ports, the flow through the thin-walled small holes is minimized by the pressure difference change.
2. The effect of temperature on flow
The oil temperature affects the viscosity of the oil. For the elongated hole, when the oil temperature changes, the flow rate will also change. For the thin wall, the viscosity of the small hole has little effect on the flow rate, so the flow rate is basically unchanged when the oil temperature changes.
3. Blockage of the throttle
The throttle of the throttle valve may be partially blocked due to impurities in the oil or colloidal or asphalt precipitated due to oxidation of the oil, which changes the flow area of ​​the original orifice and changes the flow rate. Especially when the opening is small, the effect is more prominent, and in severe cases, it will be completely blocked and the flow will be broken. The larger the flow passage area of ​​the orifice, the shorter the throttle passage and the larger the hydraulic diameter, the less likely it is to block. Of course, the cleanliness of the oil also affects the blockage. The minimum steady flow rate of a typical flow control valve is 0.05 L/min.
----- Editor-in-Chief: Dalan Oil Pump Motor 02-Procurement Consultant
Copyright http: / (Dalan Motor) Reprint, please indicate the source
Http://news.chinawj.com.cn Editor: (Hardware Business Network Information Center) http://news.chinawj.com.cn
Stainless Deep Drawing Parts,Custom Metal Fabrication Deep Drawing,Filter Cover Metal Fabrication,Custom Sheet Metal Deep Drawing
JIANGSU TONGDE INTERNATIONAL TRADE CO.LTD. , https://www.tongdetrade.com