The plunger pump is an important device for the hydraulic system. It relies on the plunger to reciprocate in the cylinder to change the volume of the sealing working chamber to achieve oil absorption and oil pressure. The plunger pump has the advantages of high rated pressure, compact structure, high efficiency and convenient flow adjustment.
Piston pumps are widely used in applications where high pressures, high flow rates, and flow rates need to be adjusted, such as hydraulic presses, construction machinery, and ships.
The plunger pump is generally divided into a single plunger pump, a horizontal plunger pump, an axial piston pump and a radial piston pump.
The structural components mainly include an eccentric wheel, a plunger, a spring, a cylinder block, and two one-way valves. A closed volume is formed between the plunger and the cylinder bore. When the eccentric rotates one revolution, the plunger reciprocates up and down once, and moves downward to absorb oil, and moves upward to drain oil. The volume of oil discharged per revolution of the pump is called displacement, and the displacement is only related to the structural parameters of the pump.
The horizontal piston pump is installed side by side by several plungers (generally 3 or 6). It uses a crankshaft to pass the connecting rod slider or directly push the plunger to reciprocate the eccentric shaft to realize the suction and discharge of liquid. Hydraulic pump. They also use valve-type flow distribution devices, and most of them are dosing pumps. The emulsion pumps in the coal mine hydraulic support system are generally horizontal piston pumps. The emulsion pump is used for the coal mining face to provide an emulsion for the hydraulic support. The working principle relies on the rotation of the crankshaft to drive the piston to reciprocate to achieve liquid absorption and drainage.
The axial piston pump (English name: Piston pump) is a plunger pump in which the reciprocating direction of the piston or plunger is parallel to the central axis of the cylinder. The axial piston pump operates with a volume change produced by the reciprocating motion of the plunger parallel to the drive shaft within the plunger bore. Since the plunger and the plunger hole are both round parts, a high precision fit can be achieved, and the volumetric efficiency is high.
Straight-axis swash plate type piston pumps are divided into two types: pressure supply type and self-suction type. Pressure-supply type hydraulic pumps mostly use a gas tank with air pressure. The hydraulic oil tank that supplies oil by pressure must operate the machine after the hydraulic oil tank reaches the air pressure after each start of the machine. If the hydraulic fluid tank is not pressurized enough to start the machine, the sliding shoes 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.
Radial piston pumps can be divided into two categories: valve distribution and shaft distribution. Valve flow radial piston pump has high failure rate and efficiency
Low disadvantages. The shaft-distributing radial piston pump developed in the 70s and 80s in the world overcomes the shortcomings of the valve-distributing radial piston pump. Due to the characteristics of the radial pump structure, the radial piston pump with fixed shaft distribution has higher impact resistance, longer service life and higher control precision than the axial piston pump. The variable stroke short pump variable is realized by changing the eccentricity of the stator under the action of the variable plunger and the limit plunger, and the maximum eccentric distance is 5-9mm (depending on the displacement), the variable stroke is very short. . And the variable mechanism is designed for high pressure operation and is controlled by a control valve. Therefore, the pump responds quickly. The radial structural design overcomes the problem of eccentric wear such as axial piston pump shoes. Its impact resistance is greatly improved.
The hydraulic piston pump relies on the pneumatic oil supply tank. After each start of the machine, the hydraulic oil tank must be used to reach the operating air pressure before the machine can be operated. The straight-axis swash plate type piston pump is divided into two types: self-suction type of pressure oil supply type. Pressure-supply type hydraulic pumps mostly use a gas tank with air pressure, and the hydraulic pump itself has a charge pump to supply pressure oil to the oil pump inlet. The self-priming hydraulic pump has a strong self-priming capability and requires no external force to supply oil.
The plunger pump is divided into two representative types of axial piston pumps and radial piston pumps; due to the radial piston pump
It belongs to a new type of high-efficiency pump with high technical content. With the accelerating localization, the radial piston pump will become an important part of the application of the plunger pump; the radial piston pump is a piston or a plunger. A plunger pump that reciprocates in a direction perpendicular to the drive shaft. The working principle of the radial piston pump: the driving torque is transmitted from the drive shaft through the cross coupling to the star-shaped hydraulic cylinder rotor, and the stator is free from other lateral forces. The rotor is mounted on the distribution shaft. A radially arranged plunger located in the rotor is attached to the eccentric stroke stator by a hydrostatically balanced shoe. The plunger is connected to the shoe hinge and locked by a snap spring. Two retaining rings clamp the shoe onto the travel stator. When the pump rotates, it relies on centrifugal force and hydraulic pressure to be placed on the inner surface. When the rotor rotates, the plunger will reciprocate due to the eccentricity determined, and its stroke is set to be twice the eccentricity. The eccentricity of the stator can be adjusted by two plungers that are opposite in radial position on the pump body. The oil enters and exits through the pump body and the flow passage on the distribution shaft, and is controlled by the suction port on the distribution shaft, and the hydraulic pressure generated in the pump body is absorbed by the static pressure balance surface. The static pressure balance of the friction pair adopts an overbalanced pressure compensation method to form an open loop control. The bearing supporting the drive shaft only serves as a support and is not affected by other external forces. In the hydraulic system: the axial piston pump works by utilizing the volume change caused by the reciprocating movement of the plunger parallel to the drive shaft in the plunger bore. Since the plunger and the plunger hole of the plunger pump are both round parts, a high precision fit can be achieved during processing;
During operation, under the action of the cam and the plunger spring on the camshaft of the fuel injection pump, the plunger is forced to reciprocate up and down, thereby completing the pumping task, and the pumping process can be divided into the following three stages. Conclusion: From the above discussion, the following conclusions are drawn: 1 The total stroke L of the plunger reciprocating motion is constant and is determined by the lift of the cam. 2 The amount of oil supplied per cycle of the plunger depends on the oil supply stroke, and the oil supply stroke is variable regardless of the camshaft control. 3 The fuel supply start timing does not change with the change of the oil supply stroke. 4 Turn the plunger to change the end of the oil supply and change the oil supply. 3. Domestic series of plunger type fuel injection pumps Domestic series of piston pumps mainly include A, B, P, Z and I, II, III and other series. The serialization is based on the requirements of the single-cylinder power range of the diesel engine. It is based on the plunger stroke, the center distance of the pump cylinder and the structural type, and is respectively equipped with plunger diameters of different sizes to form several kinds in one working cycle. Fuel injection pumps with different internal fuel supply to meet the needs of various diesel engines. The working principle and structure of the domestic series of fuel injection pumps are basically the same. The structure and working principle of the plunger type fuel injection pump are introduced by taking the A type pump as an example. The plunger pump consists of four parts: the sub-pump, the oil quantity adjustment mechanism, the transmission mechanism and the pump body.
It is intelligent control of the microprocessor, LCD display, communication with the computer, stable working pressure, small pulsation and convenient operation. It is widely used in biochemical, pharmaceutical, chemical, environmental protection and other industries to meet the requirements of continuous constant pressure and constant flow of liquids in the above industries.
The total stroke L of the reciprocating motion of the plunger pump plunger is constant and is determined by the lift of the cam. The amount of oil supplied per cycle of the plunger depends on the oil supply stroke, and the oil supply stroke is variable without being controlled by the camshaft. The fuel supply start timing does not change with the change of the oil supply stroke. Turning the plunger changes the timing of the end of the oil supply, thus changing the amount of fuel supplied. When the plunger pump is working, under the action of the cam and the plunger spring on the camshaft of the fuel injection pump, the plunger is forced to reciprocate up and down, thereby completing the pumping task, and the pumping process can be divided into the following two stages.