Structural features of hydraulic pump and motor
Structural features of hydraulic pump and motor
Structural characteristics of hydraulic pump
The structural characteristics of various hydraulic pumps are shown in the table below.
Structural characteristics of various hydraulic pumps
type |
Structure diagram |
Structural features |
Advantages and disadvantages |
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Gear pump |
External meshing |
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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 |
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Internal engagement |
Involute type |
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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 |
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Cycloid type |
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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 |
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Vane pump |
Unbalanced type (single acting) |
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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 |
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Balanced type (double acting) |
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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 |
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Screw pump |
Twin screw type |
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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 |
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Three screw type |
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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 |
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Axial piston pump ( End face distribution ︶ |
Inclined axis type |
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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 |
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Straight shaft (swash plate) |
Through shaft type |
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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 |
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Non through shaft type |
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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 |
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Radial piston type |
Valve distribution |
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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 |
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Axial distribution |
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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 |
Structural characteristics of hydraulic motor
The structural characteristics of high-speed hydraulic motor are basically similar to those of the same type of hydraulic pump, but because the structure of hydraulic pump with valve distribution can not reverse the flow of oil, it can not be used as a hydraulic motor, so there is no such valve distribution high-speed hydraulic motor.
The structural characteristics of low-speed hydraulic motors commonly used are shown in the table below.
Structural characteristics of various hydraulic motors
type |
Structure diagram |
Structural features |
Advantages and disadvantages |
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Single acting |
Radial piston type |
Crank connecting rod type |
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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 |
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No connecting rod type |
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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 |
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Swing cylinder type |
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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 |
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Axial piston type |
Double swash plate |
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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 |
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Multiple functions |
Radial piston type with inner curve |
Plunger thrust type |
Plunger roller type |
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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 |
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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 |
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Ball plunger type |
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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 |
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Beam force transfer type |
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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 |
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Roller force transfer type |
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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 |
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Connecting rod force transfer type |
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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 |
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Axial type |
Double row ball type |
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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 |