Classification of plunger pumps

Classification of plunger pumps

The plunger pump is generally divided into single plunger pump, horizontal plunger pump, axial plunger pump and radial plunger pump.

1) Single plunger pump

The structure consists of eccentric wheel, plunger, spring, cylinder block and two one-way valves. A closed volume is formed between the plunger and the cylinder block hole. The eccentric wheel rotates once, and the plunger moves up and down once. It moves downward to absorb oil and upward to drain oil. The volume of oil discharged per revolution of the pump is called the displacement, which is only related to the structural parameters of the pump.

2) Horizontal plunger pump

The horizontal plunger pump is a hydraulic pump which is installed by several plungers (generally 3 or 6) in parallel, and uses a crankshaft to directly drive the plunger through the connecting rod slider or the eccentric shaft to perform reciprocating motion to achieve liquid suction and discharge. They also use valve type flow distribution device, and most of them are fixed displacement pumps. The emulsion pump in the coal mine hydraulic support system is generally a horizontal plunger pump.

The emulsion pump is used in the coal mining face to provide emulsion for the hydraulic support. Its working principle is to drive the piston to do reciprocating motion by the rotation of the crankshaft to achieve liquid suction and discharge.

3) Axial type

The axial piston pump is a piston pump whose reciprocating motion direction of the piston or plunger is parallel to the central axis of the cylinder block. The axial piston pump uses the volume change produced by the reciprocating motion of the plunger parallel to the transmission shaft in the plunger hole to work. As the plunger and the plug hole are round parts, they can be processed with high precision, so the volumetric efficiency is high.

4) Straight shaft swashplate type

The straight shaft swashplate plunger pump is divided into pressure oil supply type and self suction type. Most of the pressure oil supply hydraulic pumps use the oil tank with air pressure. The hydraulic oil tank with air pressure oil supply must wait for the hydraulic tank to reach the use air pressure after starting the machine each time before operating the machine. If the air pressure in the hydraulic oil tank is insufficient, the machine will be started, which will pull off the slipper in the hydraulic pump and cause abnormal wear of the return plate and pressure plate in the pump body.

5) Radial type

Radial piston pump can be divided into two categories: valve port and shaft port. The radial piston pump with valve flow distribution has the disadvantages of high failure rate and low efficiency. The internationally developed axial flow radial piston pump in the 1970s and 1980s overcame the shortage of valve flow radial piston pump.

Due to the structural characteristics of the radial pump, the radial piston pump with fixed axial flow distribution has the advantages of impact resistance, long service life and high control accuracy compared with the axial piston pump. The variable of variable stroke short pump is realized by changing the eccentricity of stator under the action of variable plunger and limit plunger, and the maximum eccentricity is 5-9mm (depending on the displacement), so the variable stroke is very short. The variable mechanism is designed to be high-pressure operated and controlled by the control valve. Therefore, the response speed of the pump is fast. The radial structure design overcomes the problem of eccentric wear of slippers in axial piston pumps. The impact resistance is greatly improved.

6) Hydraulic

The hydraulic oil tank of the hydraulic plunger pump is supplied by air pressure. After starting the machine each time, the machine can only be operated after the hydraulic oil tank reaches the service air pressure. The straight shaft swashplate plunger pump is divided into two types: pressure oil supply type and self suction type. Most of the pressure oil supply hydraulic pumps use the oil tank with air pressure, and some hydraulic pumps have their own oil make-up 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.