Piston pumps are generally divided into single plunger pumps, horizontal plunger pumps, axial plunger pumps and radial plunger pumps.
1. Single plunger pump
The structural components mainly include an eccentric wheel, a plunger, a spring, a cylinder body, and two one-way valves. A closed volume is formed between the plunger and the bore of the cylinder. When the eccentric wheel rotates once, the plunger reciprocates up and down once, moves downward to absorb oil, and moves upward to discharge oil. The volume of oil discharged per revolution of the pump is called the displacement, and the displacement is only related to the structural parameters of the pump.
2. Horizontal plunger pump
The horizontal plunger pump is installed side by side with several plungers (generally 3 or 6), and a crankshaft is used to directly push the plunger through the connecting rod slider or the eccentric shaft to make reciprocating motion, so as to realize the suction and discharge of liquid. hydraulic pump. They also all use valve-type flow distribution devices, and most of them are quantitative pumps. The emulsion pumps in coal mine hydraulic support systems are generally horizontal plunger pumps. The emulsion pump is used in the coal mining face to provide emulsion for the hydraulic support. The working principle relies on the rotation of the crankshaft to drive the piston to reciprocate to realize liquid suction and discharge.
3. Axial type
An axial piston pump is a piston pump in which the reciprocating direction of the piston or plunger is parallel to the central axis of the cylinder. The axial piston pump works by using the volume change caused by the reciprocating movement of the plunger parallel to the transmission shaft in the plunger hole. Since both the plunger and the plunger hole are circular parts, a high precision fit can be achieved, so the volumetric efficiency is high.
4. Straight axis swash plate type
Straight shaft swash plate plunger pumps are divided into pressure oil supply type and self-priming oil type. Most of the pressure oil supply hydraulic pumps use an air pressure oil tank, and the hydraulic oil tank that relies on air pressure to supply oil. After starting the machine every time, you must wait for the hydraulic oil tank to reach the operating air pressure before operating the machine. If the machine is started when the air pressure in the hydraulic oil tank is insufficient, the sliding shoe in the hydraulic pump will be pulled off, which will cause abnormal wear of the return plate and the pressure plate in the pump body.
5. Radial type
Radial piston pumps can be divided into two categories: valve distribution and axial distribution. Valve distribution radial piston pumps have disadvantages such as high failure rate and low efficiency. The internationally developed axial flow radial piston pumps in the 1970s and 1980s have overcome the shortcomings of valve flow radial piston pumps. Due to the structural characteristics of radial pumps, radial piston pumps with fixed axial flow are more resistant to impact, have longer life, and have higher control accuracy than axial piston pumps. The variable stroke of short variable stroke pump is achieved by changing the eccentricity of the stator under the action of the variable plunger and the limit plunger, and the maximum eccentricity is 5-9mm (according to the displacement), and the variable stroke is very short. . The variable mechanism is designed for high-pressure operation and is controlled by a control valve. Therefore, the response speed of the pump is fast. The radial structure design overcomes the problem of eccentric wear of the sliding shoes of axial piston pumps. It greatly improves its impact resistance.
6. Hydraulic type
The hydraulic tank of the hydraulic piston pump relies on air pressure to supply oil. Every time the machine is started, the machine must be operated only after the hydraulic tank reaches the operating air pressure. Straight-axis swash plate plunger pumps are divided into two types: pressure supply type and self-priming type. Most of the pressure supply hydraulic pumps use a gas tank with air pressure, and some hydraulic pumps themselves have an oil supply sub-pump to provide pressure oil to the oil inlet of the hydraulic pump. The self-priming hydraulic pump has a strong self-priming ability and does not require external oil supply.
