Working principle and structure of positive displacement pump

Category: Water pump knowledge

2024-08-17

Positive displacement pump, also known as positive displacement pump, its working principle and structure is an important part in the field of fluid machinery. The working principle and structural characteristics of the positive displacement pump will be introduced in detail below.

1. working principle

The working principle of the positive displacement pump is based on the movement of the piston. The piston moves back and forth in the pump body to realize the suction and discharge of the liquid through the volume change. When the piston moves backward, the volume in the pump body increases, the inlet valve opens, and the suction liquid enters the pump body; When the piston moves forward, the volume in the pump body decreases, the inlet valve closes, and the outlet valve opens to discharge the liquid. In this way, the positive displacement pump can continuously suck and discharge liquid by the reciprocating motion of the piston.

The working principle of the positive displacement pump is based on the change of the volume of the pump chamber to realize the delivery of fluid. When the volume of the pump cavity increases, a negative pressure is formed, so that the liquid is sucked into the pump cavity; when the volume of the pump cavity decreases, the liquid is squeezed out of the pump cavity, thereby realizing the delivery of the liquid. The workflow typically consists of the following steps:

1. Suction process: When the inlet pressure of the pump is lower than the outlet pressure, the liquid is sucked into the pump cavity.

2. Compression process: through the driving device (such as motor) to drive the rotation of the pump, so that the volume of the pump cavity is reduced, the liquid is squeezed.

3. Discharge process: The compressed liquid flows out from the outlet of the pump under high pressure.

2. structure characteristics

The structure of the positive displacement pump is relatively simple, mainly composed of the pump body and the piston. The pump body is usually a sealed cavity with a piston and an inlet and outlet valve inside. The piston is a key component of the positive displacement pump, which forms a sealed working chamber with the pump body. The piston consists of one or more sealing rings to ensure that the liquid does not leak. The crankshaft is the component that connects the piston and the power source (such as a motor or engine). It converts the rotary motion into the reciprocating motion of the piston. The structural design of the positive displacement pump to meet its working principle as the core, the main structural features include:

1. Pump body: The pump body is the main component of the positive displacement pump. It is usually made of metal or engineering plastics and has good wear resistance and corrosion resistance.

2. Rotating parts: including rotors, gears, cams, etc., which are driven by the driving device to rotate to change the volume of the pump cavity.

3. Pump cavity: The pump cavity is a key part of liquid suction and discharge, and its shape and size determine the displacement of the pump.

4. Inlet and outlet: connect the liquid inlet pipe and outlet pipe respectively to realize the inflow and outflow of liquid.

5. Sealing device: In order to ensure the normal operation of the pump, the positive displacement pump is usually equipped with a sealing device to prevent liquid leakage.

6. Drive device: usually a motor, which realizes the operation of the pump by driving the rotating parts.

In addition, there are many types of positive displacement pumps, such as gear pumps, screw pumps, vane pumps, etc. Different types of positive displacement pumps are different in structure and performance.

The advantage of positive displacement pumps is that they can provide high pressure and flow, which is suitable for various demanding industrial and agricultural applications. Volumetric pumps are widely used in oil fields, chemical industry, metallurgy, construction and other fields to transport various liquids, such as oil, water, acid and alkali solutions, etc. In addition, the positive displacement pump also has the characteristics of simple structure, convenient maintenance and long service life.

In general, the working principle of the positive displacement pump is based on the change of the volume of the pump chamber to achieve the delivery of liquid, and its structural design is to meet this principle as the core. Understanding the working principle and structural characteristics of the positive displacement pump will help to better understand and apply the positive displacement pump, so that it can play a greater role in the field of fluid machinery.

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