Why piston pumps have higher oil pressure than gear pumps and vane pumps

Disadvantages of diaphragm pumps: 1. It needs to work continuously; 2. High maintenance cost; 3. It is difficult to absorb materials, and it is easy to produce cavitation phenomenon - that is, air enters the pump (usually caused by the insufficient power of the pump to transport the coating); 4. Cannot handle high-viscosity paints (as mentioned above); 5. Must be kept clean (small moving parts); 6. It needs to be continuously maintained; 7. Hydraulic oil is easy to leak; 8. The diaphragm often fails. Piston pump disadvantages:

1. The manufacturing cost is high; 2. The purchase cost is high, and the diaphragm pump uses eccentric bearings and pistons to generate movement to drive the diaphragm movement and pressurize the coating. When the motor rotates, the eccentric bearing also rotates, and one end of the piston rests on the eccentric bearing. The rotation of the eccentric bearing causes the piston to move up and down, and when the piston goes down, the diaphragm is depressed, and the inlet valve opens to suction the material.

When the piston goes up, the membrane....

The high pressure of the piston pump can reach 39MPa, which is mostly used in construction machinery, such as excavators, and the main pump of the excavator is generally a double pump, with a rated pressure of 34MPa, and the maximum pressure in an instant can reach 39MPa. The reason why piston pumps have higher oil pressure than gear pumps and vane pumps is because of their higher work and volumetric efficiency.

This pressure depends on their internal structure. Piston pumps are positive displacement pumps, and as long as the torque is sufficient, the pressure can reach 400 bar, and the two-vane pump up to 100 bar is already very remarkable.

Gear and vane pumps are subjected to radial forces and blades under pressure on the shaft, so very high pressures cannot be used.

The biggest difference between gear pumps, vane pumps and piston pumps is that the structural characteristics are different. The advantages of gear pump are simple structure, easy maintenance, long service life, and strong anti-pollution ability compared with the other two pumps. The advantages of vane pumps are compact structure, smooth movement, uniform flow and low noise.

The advantages of the piston pump are high precision, good sealing performance and high working pressure. Gear pumps are generally used in construction machinery, mining machinery, lifting and transportation machinery, construction machinery, petroleum machinery, agricultural machinery and other pressure processing equipment with harsh working conditions. Vane pumps are widely used in machine tools.

Piston pumps are mainly used in high-pressure mechanical and hydraulic drive systems. Gear pumps.

The size is small, the structure is simple, the cleanliness requirements for the oil are not strict, and it is cheaper; However, the pump shaft is not subject to the balance force, the wear is serious, and the leakage is large.

Vane pumps. It is divided into double-acting vane pumps and single-acting vane pumps. This kind of pump has uniform flow, stable operation, low noise, higher working pressure and volumetric efficiency than gear pumps, and more complex structure than gear pumps.

Piston pumps. High volumetric efficiency, small leakage, can work under high pressure, mostly used in high-power hydraulic systems; However, the structure is complex, the material and processing accuracy are high, the most expensive, and the cleanliness of the oil is high.

Generally, piston pumps are used when gear pumps and vane pumps cannot meet the requirements. There are some other forms of hydraulic pumps, such as progressive cavity pumps, etc., but the application is not as common as the above 3.

1. Gear pump.

Features: simple and compact structure, small size, light weight, good manufacturability, cheap, strong self-priming, insensitive to oil pollution, large speed range, ability to withstand impact loads, easy maintenance, reliable work.

Place of use: Applied to mechanical mountain oak manufacturing.

2. Vane pump.

Features: simple structure, uniform flow, large displacement, high efficiency.

Place of use: A pump that is applied to the power element and presses the suction liquid from the inlet side to the oil discharge side.

3. Piston pump.

Characteristics: It can generate high pressure, but the displacement is small, and it cannot convey liquids containing suspended solids.

Place of use: It is widely used in high pressure, bright and large flow and the occasion where the flow needs to be adjusted, such as hydraulic presses, construction machinery and ships.

Gear pumps, vane pumps and piston pumps are common industrial pumps, each of which has different characteristics and applications.

Gear pumps. Gear pump is a common forward displacement pump, which is characterized by simple structure, small size, light weight, low cost and easy maintenance. Gear pumps are suitable for conveying low-viscosity liquids such as water, oil, and solvents.

However, gear pumps have poor sealing properties and are not suitable for conveying highly viscous liquids and volatile liquids.

Vane pumps. The vane pump is a centrifugal pump, which is characterized by large flow rate and high head, and is suitable for conveying high viscosity liquids and volatile liquids. The structure of the vane pump is relatively complex, high and difficult to maintain. Vane pumps are suitable for chemical, petroleum, pharmaceutical and other industries.

Piston pumps. The piston pump is a positive displacement pump that is characterized by a stable flow rate and high pressure, and is suitable for conveying highly viscous liquids and liquids that are easy to crystallize. The structure of the piston pump is more complex, the highest is higher, and the maintenance is more difficult.

Piston pumps are suitable for chemical, petroleum, pharmaceutical and other industries. In general, gear pumps, vane pumps and piston pumps have different characteristics and applications, and the right pump needs to be selected according to the specific industrial application.

1. The structure is different.

Gear pumps. Inside the housing of the pump there is an external meshing gear.

Vane pump: The pump consists of a rotor, a stator.

and blades.

Piston pumps. Piston pumps are mainly composed of swash plates, sliding shoes, plungers, etc.

2. The characteristics are different.

The gear pump is small in size, simple in structure, and has less strict requirements for the first cleanliness of the oil, which is cheaper; However, the pump shaft is unbalanced, the wear is serious, and the leakage is large.

Vane pump has uniform flow, stable operation, low noise, higher working pressure and volumetric efficiency than gear pump, and more complex structure than gear pump.

Piston pumps have high volumetric efficiency, low leakage, and can work at high pressures, mostly used in high-power hydraulic systems.

However, the structure is complex, the material and processing accuracy are high, the most expensive, and the cleanliness of the oil is high.

Precautions. In addition to preventing dry rotation and overload, preventing suction air and excessive suction vacuum, the management points of vane pumps should also pay attention to:

1. If the pump steering changes, the suction and discharge direction will also change, and the vane pump has a specified steering, and it is not allowed to reverse. Because the rotor leaf groove is sloped, the blades are chamfered.

The bottom of the blade is connected with the oil discharge chamber, and the throttle groove and suction and discharge ports on the oil distribution plate are designed according to the established steering. Reversible vane pumps must be specifically designed.

2. Vane pump assembly, oil distribution pan and stator are correctly positioned with positioning pins, blades, rotors, and oil distribution pans are not allowed to be reversed, and the suction area part of the inner surface of the stator is the most easy to wear, and it can be flipped and installed if necessary, so that the original suction area becomes the discharge area and continues to be used.

3. Disassemble and assemble, pay attention to the cleanliness of the working surface, and the oil should be well filtered during work.

4. If the gap between the blades in the leaf groove is too large, the leakage will increase, and if the blades are too small, the blades will not be able to expand and contract freely, which will lead to abnormal work.

5. The axial clearance of the vane pump has a great influence on V. Small pumps ; Medium Pumps.

6. The temperature and viscosity of the oil should not exceed 55 in a liter cavity, and the viscosity is required to be between 17 and 37mm2 s. If the viscosity is too large, it is difficult to absorb oil; If the viscosity is too small, the leakage will be serious. As a pump product, vane pumps refer more to sliding vane pumps.

Vane pumps are almost exclusively referred to as sliding vane pumps.

Vane pumps and piston pumps are two different types of pumps, and they have some differences in structure and working principle

Structure: The vane pump is a centrifugal pump, which consists of a rotor and a fixed shell, and the rotor is attached to the vane, and the liquid is pumped into the pump from the inlet through the rotation of the rotor and discharged by centrifugal force. The piston pump is a positive displacement pump, which consists of a plunger, a cylinder and a valve, the plunger moves back and forth in the cylinder body, and the liquid is sucked in from the inlet and discharged through the valve through the movement of the plunger.

Working principle: The vane pump uses centrifugal force to pump the liquid in and out, the rotation of the rotor makes the liquid form a vortex in the pump, and the liquid is pushed to the outlet of the pump due to the action of centrifugal force. The piston pump realizes the suction and discharge of liquid through the reciprocating motion of the plunger, and the plunger changes the volume in the cylinder when it moves, resulting in positive displacement.

Applications: Vane pumps are typically used to handle clean or low-concentration liquids, and are suitable for water supply, circulating water, and air-conditioning systems. Piston pumps are usually used for high-pressure, high-viscosity or liquids containing and burning particulate matter, and are suitable for chemical, petroleum, metallurgical and other industries.

In general, vane and piston pumps are significantly different in structure and operating principle, suitable for different operating conditions and liquid characteristics. Choosing the right pump type for your specific needs depends on the specific application requirements.