Types and characteristics of screw pump
Types and characteristics of screw pump
Screw pump is used to transport the working medium along the axial direction by one or several mutually meshing screws rotating in the common casing. Its simplest form is a shaft with spiral blades in the cylinder. It has been thousands of years since people used this kind of device to lift materials such as water or building mortar. Archimedes screw pump (see Figure 1-4) is one of the devices originated from this.
As seen from the cross section of the screw, the screw is meshed like a special gear, so sometimes the screw pump is listed in the gear pump.
(1) Type characteristics
① The detailed classification of classification screw pump is shown in Figure a. the working condition of non sealing type (continuous liquid column type) pump is similar to that of screw conveyor in food machinery, and it is more suitable for conveying viscous materials. In the field of hydraulic engineering, generally only sealed screw pump is used.
The screw of single screw pump has a circular normal cross section, which is made of special rubber and other elastic materials. It is mainly used for conveying materials. The displacement of twin-screw pump can be very large, which is mainly used for conveying and rarely used as hydraulic pump. Pumps with more than three screws are rare. Three screw pump is mainly used in hydraulic engineering.
② The characteristics are shown in the table below
Characteristics of screw pump
|
Main advantages |
主要缺点 |
|
①运转平稳，输出流量几乎无脉动，在各类液压泵中噪音最低 ②转速和排量范围均很宽，是输出流量最大的一类液压泵 ③自吸能力强 ④对介质黏度适应性强，可输送从黏度极低的溶液、油料、水溶液直到黏度很高的油脂、胶体、软膏等各种中性或腐蚀性的物料，甚至半固体或固液、固液气多相混合物 ⑤运动部件少，工作可靠，寿命长 |
①螺杆制造较困难，价格贵 ②结构笨重，功率密度低 ③容积效率较低，一般适用于低压系统 |
