Product Introduction

A hydraulic coupling is a mechanical device that transfers rotational speed using a liquid medium. Its driving input shaft end is connected to the original drive motor, while the driven output shaft end is connected to the load shaft end. By adjusting the pressure of the liquid medium, the rotational speed of the output shaft can be altered. In an ideal state, as the pressure approaches infinity, the output speed equals the input speed, equivalent to a rigid coupling. As pressure decreases, the output speed accordingly reduces; by continuously changing the medium pressure, the output speed can be infinitely adjusted below the input speed. The power control and speed regulation principle and efficiency of a hydraulic coupling are based on its aforementioned characteristics. A hydraulic coupling is a type of energy-consuming mechanical speed regulating device; the deeper the speed regulation (the lower the speed), the greater the loss, especially for constant torque loads. Since the input power of the original drive remains constant, the loss of power increases proportionally with the speed loss. For loads such as fans and pumps, where the load torque varies with the square of the speed, the input power of the original drive decreases at the square rate of the speed, resulting in relatively smaller loss of power. However, the output power decreases at the cubic rate of the speed, so the speed regulation efficiency remains low. The speed regulation efficiency curve of a hydraulic coupling has an average efficiency of around 50%. A non-rigid coupling that uses liquid as the working medium is also known as a hydraulic coupling.

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Product Features

The impeller and turbine of a hydraulic coupling form a sealed working chamber that allows for the circulation of fluid. The impeller is mounted on the input shaft, while the turbine is mounted on the output shaft. As the power source (internal combustion engine, electric motor, etc.) rotates the input shaft, the fluid is ejected by the centrifugal impeller. This high-speed fluid, upon entering the turbine, drives it to rotate, transferring the energy obtained from the impeller to the output shaft. The fluid then returns to the impeller, creating a continuous cycle. The hydraulic coupling transmits torque by changing the momentum moment through the interaction between the fluid and the blades of the impeller and turbine. Its output torque is equal to the input torque minus the frictional torque, hence it is always less than the input torque. The input and output shafts of the hydraulic coupling are connected by the fluid, with no rigid connections between the working components. The hydraulic coupling's features include: the ability to eliminate shock and vibration; an output speed lower than the input speed, with the speed difference between the shafts increasing with load; good overload protection and starting performance, allowing the input shaft to continue rotating even when the load is too high and the shaft stops, preventing damage to the power source; and when the load decreases, the output shaft speed increases until it approaches the input shaft speed. The transmission efficiency of the hydraulic coupling is the ratio of the product of the output shaft speed and output torque (output power) to the product of the input shaft speed and input torque (input power). Generally, a hydraulic coupling can achieve higher efficiency when the normal operating speed ratio is above 0.95. The characteristics of the hydraulic coupling vary due to the different shapes of the working chamber and the impeller and turbine. If the fluid in the hydraulic coupling is drained, the coupling is disengaged and can act as a clutch.