Structural features of hydraulic pump and motor

type

Structure diagram

Structural features

Advantages and disadvantages

Gear pump

External meshing

The function of the pump is completed by using the change of the closed volume formed by the gear teeth and the pump shell. Variable cannot be used

The most simple structure, low price. Large flow pulsation, radial load and noise

Internal engagement

Involute type

Use the volume formed by gear teeth and ring gear to complete the function of pump. There are suction and discharge ports in the axisymmetric position. Variable cannot be used

The size is slightly smaller than the external meshing type, the price is slightly higher than the external meshing type, the flow and pressure pulsation are small, and the noise is low. Large radial load

Cycloid type

Use the volume formed by gear teeth and ring gear to complete the function of pump. There are suction and discharge ports in the axisymmetric position. Variable cannot be used

Small size, low price, low pressure and large radial load

Vane pump

Unbalanced type

(single acting)

The function of the pump is completed by using the volume change between the blades inserted into the rotor slot. A group of oil suction ports and oil discharge ports are arranged on the axisymmetric position. Change the stator eccentricity e for variable

The radial load is large, the noise is low, and the flow fluctuation is larger than that of the balanced type

Balanced type

(double acting)

The function of the pump is completed by using the volume change between the blades inserted into the rotor slot. A group of oil suction ports and oil discharge ports are arranged on the axisymmetric position

Small radial load, low noise and small flow fluctuation

Screw pump

Twin screw type

The function of the pump can be achieved by using the volume of the screw groove. Variable cannot be used

No flow pulsation, large size and weight, large radial load

Three screw type

The function of the pump can be achieved by using the volume of the screw groove. Variable cannot be used

No flow pulsation, large size and weight, smaller radial load than twin screw

Axial piston pump (

End face distribution

︶

Inclined axis type

The cylinder block is driven to rotate by the ball joint connecting rod between the plunger and the driving plate, and the torque is transmitted by the connection between the conical surface of the connecting rod and the inner wall of the plunger. Using end port, including spherical port plate. In this paper, a new type of inclined shaft pump with plunger and connecting rod as a whole has appeared

Strong structure, impact resistance, anti pollution, new better than swash plate. Because of the "triangle" structure, the volume of the pump is greatly reduced. As the cylinder tilt angle increases to 40 ° with variable speed, the power to weight ratio further increases

Straight shaft (swash plate)

Through shaft type

The transmission shaft passes through the swash plate, and the radial load is supported by the transmission shaft. Using port plate to distribute flow

It is light in total, small in volume and few in parts. It can be connected in series with auxiliary pumps for easy integration. However, the diameter of the feeding hole is large. The inclination moment of the donor is borne by Zhuzhou, so the diameter of the transmission shaft is larger

Non through shaft type

Use the port plate to distribute the flow. The radial load is balanced by the large bearing around the cylinder block to limit the inclination of the cylinder block

The transmission shaft only transmits torque and its diameter is small. Because of the tilting moment of the cylinder block, the manufacturing accuracy is required to be high, otherwise the valve plate is easy to be damaged

Radial piston type

Valve distribution

The eccentric movement of the crankshaft makes the plunger move back and forth, and the one-way valve is used to distribute the flow

High working pressure, little pollution to oil. There are many parts. Most of them are quantitative pumps. There is a pump with its own pressure to close the single plunger structure, which can achieve variable or constant power control

Axial distribution

The stator shell is eccentric from the cylinder block, and the flow is distributed by the distribution shaft, and the plunger end directly contacts with the stator shell

The radial dimension is large, and the plunger head is easy to wear. The high and low pressure cavities of the port shaft diameter are unbalanced and easy to wear

type

Structure diagram

Structural features

Advantages and disadvantages

Single acting

Radial piston type

Crank connecting rod type

The oil pressure acts on the plunger, and the hydraulic pressure acts on the eccentric crankshaft through the connecting rod, so as to make the motor shaft rotate

The plunger is small in lateral force, reliable in operation, but large in volume

No connecting rod type

The oil pressure acts directly on the eccentric crankshaft, which makes the motor shaft rotate or the housing rotate

Large volume, large lateral force of plunger

Swing cylinder type

The oil pressure acts directly on the drum eccentric shaft, which makes the motor shaft rotate. The plunger is in the form of extended sleeve and swings with the rotation of crankshaft

The plunger has no lateral force and is statically balanced with large volume

Axial piston type

Double swash plate

The oil enters into the rotor cylinder hole through the end port plate, and the oil pressure pushes the plunger and chemical action on the swash plate to produce tangential force, which is the cause of rotor rotation

Small volume, low side force of plunger

Multiple functions

Radial piston type with inner curve

Plunger thrust type

Plunger roller type

The tangential force produced by the roller acting on the guide rail is directly transmitted to the rotor by the plunger, so that the rotor rotates

The volume is small and the specific pressure of plunger is large

Roller plunger type

The tangential force produced by the roller acting on the guide rail is directly transmitted to the rotor by the roller, so that the rotor rotates

Small volume, high working pressure, angle steel ball plunger type

Ball plunger type

The tangential force produced by the roller acting on the guide rail is directly transmitted to the rotor by the roller, so that the rotor rotates

Small volume, volume efficiency, low working pressure

Beam force transfer type

The tangential force generated by the roller acting on the guide rail is transmitted to the rotor by the rectangular beam, so that the rotor rotates

The plunger has no side force and works reliably

Roller force transfer type

The tangential force generated by the working roller acting on the guide rail is transmitted to the rotor by the guide roller, so that the rotor rotates

The plunger has no side force, the transmission parts are rolling friction, and the work is reliable. The structure is complex

Connecting rod force transfer type

The tangential force produced by the roller acting on the guide rail is transmitted to the rotor by the hinged connecting rod, so that the rotor rotates

The lateral force of plunger is very small and the structure is complex

Axial type

Double row ball type

钢球作用于导轨所产生的切向力，直接由钢球传递给转子，从而使转子旋转

体积较小，定子曲线加工工艺性差，可靠性较差