I. Classification of piston pumps
Piston pumps are generally divided into single piston pumps, horizontal piston pumps, axial piston pumps and radial piston pumps.
1,Single-plunger pump
The structure consists of eccentric wheel, plunger, spring, cylinder, two check valves. Plunger and cylinder hole to form a closed volume. Eccentric wheel rotation of a turn, the plunger up and down reciprocating movement once, downward movement of oil suction, upward movement of oil discharge. The volume of oil discharged by the pump per revolution is called displacement, and the displacement is only related to the structural parameters of the pump.
2,Horizontal piston pump
Horizontal piston pump is made of several plungers (generally 3 or 6) installed side by side, with a crankshaft through the connecting rod slider or by the eccentric shaft to promote the plunger directly to do the reciprocating motion, to realize the suction and discharge of liquid hydraulic pumps. They also all use valve type flow distribution device, and most of them are quantitative pumps. The emulsion pump in the hydraulic support system of coal mine is generally a horizontal plunger pump. The emulsion pump is used in the coal mining face to provide emulsion for the hydraulic support, and the working principle relies on the rotation of the crankshaft to drive the piston to do reciprocating motion to realize the suction and discharge of liquid.
3,Axial type
Axial piston pump (Piston pump) is the piston or plunger reciprocating motion direction parallel to the cylinder center axis of the piston pump. Axial piston pumps use the plunger parallel to the drive shaft in the plunger hole reciprocating motion generated by the volume change to work. Because the plunger and the plunger hole are round parts, can achieve a high degree of accuracy with, so high volumetric efficiency.
4,Straight shaft swash plate type
Straight shaft swashplate piston pumps are divided into two types: pressure-supplied oil and self-priming oil. Pressure supply type hydraulic pumps are mostly used with air pressure tank, hydraulic oil tank by air pressure supply, after each start the machine, you must wait for the hydraulic oil tank to reach the use of air pressure before operating the machinery. If the hydraulic oil tank air pressure is not enough to start the machine, will be the hydraulic pump within the slide shoe caused by the phenomenon of pulling off, will cause the pump body return plate and the pressure plate of the abnormal wear.
5,Radial type
Radial piston pumps can be divided into two categories: valve flow and shaft flow. Valve flow radial piston pumps have the disadvantages of high failure rate and low efficiency. Internationally, the 70's and 80's development of the shaft flow radial piston pump to overcome the shortcomings of the valve flow radial piston pump. Due to the characteristics of the radial pump structure, fixed axial flow radial piston pump than axial piston pump shock resistance, long life, high control accuracy. Variable stroke short pump variable is in the variable plunger and limit plunger role, change the stator eccentricity to achieve, and fixed the maximum eccentricity of 5-9mm (according to the size of the displacement is different), variable stroke is very short. And the variable mechanism is designed for high-pressure manipulation, controlled by the control valve. Therefore, the response speed of the pump is fast. Radial structure design overcomes the problem of axial piston pump slide shoe wear. So that its impact resistance is greatly improved.
6,Hydraulic
Hydraulic piston pumps rely on air pressure to supply oil to the hydraulic tank, after each start-up machine, you must wait for the hydraulic tank to reach the use of air pressure before operating the machinery. Straight shaft swash plate piston pump is divided into pressure oil-supplied type of self-priming oil type two. Pressure oil-supplied hydraulic pumps are mostly used with air pressure tank, there are also hydraulic pumps themselves with oil replenishment sub-pump to the hydraulic pump inlet to provide pressure oil. Self-priming oil type hydraulic pump self-priming ability is very strong, without external oil supply.
II, variable piston pump
Variable piston pump pressure oil through the pump body, pump casing variable casing through the hole in the oil through the check valve into the variable casing of the lower chamber, when the tie rod downward movement, push the servo piston downward movement, the servo valve of the upper valve opening, variable casing of the lower chamber of the pressure oil through the variable piston through the hole in the variable casing of the variable casing into the upper chamber, due to the area of the upper chamber is larger than the lower chamber, the hydraulic pressure to promote the downward movement of the piston, driving the pin so that the variable head around the center of the steel ball to rotate, change the variable head tilt angle (increase), the flow rate increases. As the area of the upper chamber is larger than the lower chamber, the hydraulic pressure pushes the piston to move downward, driving the pin to rotate the variable head around the center of the steel ball, changing the tilt angle of the variable head (increasing), and the flow rate of the piston pump increases. On the contrary, when the tie rod moves upward, the tilt angle of the variable head changes in the opposite direction, and the flow rate of the pump also changes. When the tilt angle to zero, the variable head to the direction of the negative declination changes in the direction of the liquid flow generated by the commutation, the pump inlet and outlet changes.
III , plunger pump working principle dynamic diagram
