A hydraulic coupling is a mechanical component used to connect two shafts (active shaft and passive shaft) in different mechanisms to rotate together and transmit torque. When the machine is running, the two shafts cannot be separated. Only after the machine is parked and the connection is disconnected, can the two shafts be separated. In high-speed and heavy-duty power transmission, some couplings also have the functions of buffering, vibration reduction, and improving the dynamic performance of the shaft system.

Production cycle: 30 days, warranty period: 1 year

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Definition and Basic Principles

A hydraulic coupling is a device that uses liquid (usually oil) to transmit power. It mainly consists of a driving shaft part, a driven shaft part, and a working chamber filled with liquid. The basic principle is based on the viscosity and incompressibility of liquids. When the driving shaft rotates, it drives the liquid inside the working chamber to rotate. Due to the viscosity of the liquid, the interaction between liquid molecules drives the driven shaft to rotate, thereby achieving the transmission of power from the driving shaft to the driven shaft.

Structural composition

Shell: The shell of a hydraulic coupling is a metal shell that serves to protect internal components and contain liquids. The casing usually has sufficient strength and sealing to prevent liquid leakage. Its shape varies depending on the type and application scenario of the coupling, commonly including cylindrical and square shapes.

Connecting components of driving shaft and driven shaft:

The active shaft section includes an input shaft and an inner rotor (or inner impeller) connected to it. The input shaft is connected to a power source (such as an electric motor, engine, etc.), and the structural design of the inner rotor (or inner impeller) is to effectively agitate the liquid inside the working chamber during rotation.

The driven shaft part includes the output shaft and the external rotor (or impeller) connected to it. The output shaft is connected to the driven device, and the outer rotor (or outer impeller) corresponds to the inner rotor (or inner impeller). Under the drive of the liquid, it rotates with the rotation of the inner rotor (or inner impeller), thereby transmitting power to the output shaft.

Working chamber and fluid: The working chamber is a space located between the connecting components of the driving shaft and the driven shaft, filled with hydraulic oil. The properties of hydraulic oil, such as viscosity, have a significant impact on the performance of couplings. The sealing of the working chamber is crucial, and rubber seals or mechanical seals are usually used to prevent liquid leakage.

working process

When the power source drives the main shaft to rotate, the inner rotor (or inner impeller) on the main shaft begins to stir the hydraulic oil in the working chamber. Due to the viscosity of hydraulic oil, shear forces are generated between oil molecules, causing the oil to form a circulation. This circulation acts on the outer rotor (or outer impeller), driving the driven shaft to rotate. The size of power transmission can be controlled by adjusting the amount of liquid in the working chamber or the viscosity of the liquid. For example, increasing the amount of liquid or using liquids with higher viscosity can improve the efficiency of power transmission to some extent, but it can also increase the resistance to rotation.

advantage

Good shock absorption and buffering performance: Hydraulic couplings can effectively buffer and absorb vibrations and impacts from power sources. Due to the inherent elasticity and damping properties of liquids, when there are fluctuations in the output of the power source or external impacts on the equipment, hydraulic couplings can reduce these effects and protect the connected equipment through the deformation and flow of the liquid.

Overload protection function: When the load suddenly increases beyond the rated torque of the coupling, the liquid inside the hydraulic coupling can slide. This sliding can prevent equipment damage caused by the rigid connection between the power source and the driven device, and serve as overload protection.

Can achieve stepless speed regulation: By changing the amount or viscosity of the liquid in the working chamber, stepless speed regulation can be achieved within a certain range. This is very useful for equipment that requires flexible adjustment of speed according to operating conditions, such as drive equipment in certain industrial production lines.

Disadvantages and countermeasures

Liquid leakage problem: Due to the dependence of hydraulic couplings on liquid for operation, if the seal is poor, liquid leakage can lead to performance degradation or even malfunction. The response measures include regular inspection of the condition of the seals, timely replacement of aging or damaged seals, and improving the reliability of the sealing structure in the design and manufacturing process, such as using dual sealing structures or high-quality sealing materials.

Relatively low efficiency: Compared to some rigid couplings, hydraulic couplings experience energy loss during power transmission due to factors such as internal friction of the liquid, resulting in relatively low efficiency. Energy loss and efficiency can be reduced by optimizing the design of the working chamber, selecting liquids with appropriate viscosity, and improving manufacturing processes.

Application scenarios

Ship power system: Hydraulic couplings can be used between the main engine and propulsion shaft system of a ship to transmit power, buffer the vibration and impact of the main engine, and protect the propulsion shaft system. At the same time, hydraulic couplings can also play a good role in power distribution or collaborative work between different equipment on ships.

Industrial equipment: In large-scale equipment such as crushers, mixers, and conveyor belts in metallurgy, chemical, mining, and other industries, hydraulic couplings can be used to connect motors and working equipment, achieving smooth power transmission, overload protection, and speed regulation functions.