1. The function of hydraulic coupling
1 has the performance of slowing down impact and isolating torsional vibration; it can cause a delay time for the motor to start, accelerate slowly, and reduce the mutual impact between parts caused by sudden start.
2 has the performance of light-load starting of the motor: Since the pump wheel torque of the coupling is proportional to the square of its rotation speed, at the moment of starting, the pump wheel has very little torque due to the low speed, and the motor is similar to starting with a pump wheel without load, so the starting time is short, the starting current is small, and the starting is smooth, especially suitable for starting heavy loads with large inertia.
3, with overload protection performance: Since the coupling has no direct mechanical connection, when the external load exceeds a certain limit, the pump wheel torque will no longer rise. At this time, the motor will continue to rotate as usual, and the output will decelerate until it stops. The power absorbed from the power supply is converted into heat energy to heat the coupling until the fusible plug sprays liquid. The input and output are cut off, protecting the motor and the working machine from damage, thereby reducing the machine failure rate, maintenance costs and downtime, and extending the service life of the motor-loaded working machine.
4. Power-saving performance: Because the coupling effectively addresses motor starting difficulties and motor oversizing, the motor can be reduced by at least one frame size compared with a rigid drive. It also reduces starting current and duration, lessening the impact on the electrical grid and achieving energy savings of 10–20%, particularly when starting heavy loads with high inertia. Features of a torque-limiting fluid coupling: Apart from the bearings and oil seals, there is no mechanical rubbing wear. It offers long service life, a low failure rate, and no need for special maintenance.
2. Use and maintenance of speed-adjustable hydraulic coupling
1, pre-start check
(1) Check the oil gauge to confirm whether the oil level is appropriate;
(2) Check whether the coupling and cooler pipelines are connected correctly;
(3) Check whether the electrical circuits of each instrument are connected correctly;
(4) Check whether the coupling and protective cover are installed correctly;
(5) Check whether the oil amount in the coupling tank is appropriate. When the oil temperature is lower than 5°C, use an electric heater to heat the working oil;
(6) Check that the coupling guide is adjusted to the low speed device.
2, run
(1) Coupling is equipped with electric actuator, by manual. Manually operated electric or automatically controlled electric actuator is used to adjust the position of the conduit and change the liquid filling degree in the coupling cavity, thus changing the output speed and output torque of the coupling.
(2) The coupler has a low speed when the conduit is fully inserted (0% position), and a high speed when the conduit is fully pulled out (100% position) (up to rated speed and rated power). When adjusting the conduit opening from the 0% position to the 100% position, the speed should not be too fast, usually within 25 seconds.
(3) The speed regulation range of the coupling varies with different working machines. Matched with centrifugal machinery, the speed adjustment range is 1-1/5, matched with constant torque machinery, the speed adjustment range is 1-1/3.
(4) The speed-regulating hydraulic coupling is matched with the centrifugal machinery. In the heating working condition, at the speed ratio i=0.66, the heating power loss is approximately 15% of the rated power of the motor. Therefore, during use, you should try to avoid working near hot spots for a long time.
(5) Constant torque machinery is equipped with a speed-regulating coupling. The speed ratio i is equal to the efficiency. That is, the greater the speed regulation, the greater the power loss and the greater the heat generation. Therefore, the speed regulation of constant torque machinery equipped with a speed-regulating hydraulic coupling should not be too large, especially if it cannot operate at a large speed ratio for a long time.
(6) When the coupling output speed is very low, that is, when the conduit position is close to the 0% position, noise that has not occurred during operation within the normal operating range may occur. This is due to the "whistle effect" produced by the intersection of the conduit port and the drain hole on the outer edge of the pump impeller. If this happens, it can be resolved by slightly raising the position of the conduit, and it is not considered a coupling failure.
(7) Check whether the coupling oil temperature and oil pressure are normal at any time during operation. If an abnormality is found, the cause should be found and eliminated in time.
3, maintenance
(1) Regularly check the oil level in the fuel tank and refill it in time;
(2) The oil filter of the oil suction pipe should be removed and cleaned after the first operation of the new machine500;
(3) In conjunction with the shutdown of the working machine for maintenance, the oil supply pump and oil filter should be cleaned regularly;
(4) Check the oil quality regularly and replace qualified working oil in time;
(5) If you need to drain the oil in the coupling box, you can unscrew the oil drain hole plugs at the lower part of the input and output ends of the box, or install a stop valve at the oil drain hole.
3. Trial and maintenance of torque-limiting hydraulic coupling
1. Rapid and frequent forward and reverse rotations are not allowed. Theoretically speaking, the coupling can rotate forward and reverse, but rapid forward and reverse rotation will damage the connecting parts of the coupling due to too much inertial force. Therefore, strict compliance with operating procedures is required to avoid sharp and frequent forward and reverse rotations. Special attention should be paid to this point when using couplings on main engines such as tower cranes and bridge cranes.
2, the steering of the coupling output shaft is the same as the steering of the motor shaft. During the first test run, check whether the motor steering meets the requirements.
3. When the motor reaches the rated speed, the driven machine must start to transfer. If the driven machine does not move, it must be stopped immediately to check whether the load is too large and causes braking.
4. During continuous operation, the operating temperature of the coupling shall not exceed 90℃, and the working temperature of the water medium shall not exceed 100℃.
5 and regularly (every 3000 hours) the quality of the working oil should be checked. If the oil quality is found to have deteriorated, it should be replaced immediately.
6, regularly check the position accuracy of the motor shaft and the working machine shaft and correct it at any time.
7. Regularly check the installation foundation of the motor and working machine to avoid early damage caused by vibration waves caused by poor foundation rigidity and affecting the coupling.
8. Regularly check the wear of the elastic block or elastic disc of the elastic coupling and replace it regularly.
9. It is not allowed to disassemble the coupling housing at will, so as not to damage the sealing, assembly accuracy and balance accuracy, leading to accidents.
10, it is not allowed to change the coupling oil medium to water medium.
11. It is not allowed to flush the liquid at will, let alone full filling. It should be flushed strictly according to the instructions.
12. In a coupling with a bearing cavity, the bearing cavity has been filled with grease (commonly known as glycerin) before leaving the factory. When the coupling is in operation, the grease becomes thinner and leaks out due to the heat generated by the bearing. This is not a leakage of the coupling's working medium, and attention should be paid to the difference.
13. In order to facilitate the heat dissipation of the self-cooling hydraulic coupling, the fluid coupling should be placed in a well-ventilated place to assist cooling.
14. To prevent accidents, the coupling should be installed with a reliable protective cover.
4. Filling and inspection of hydraulic coupling
The filling amount of torque-limiting hydraulic coupling:
1) The liquid filling amount of a torque-limiting hydraulic coupling is proportional to the transmission power. That is, within the specified liquid filling range, the greater the liquid filling amount in the working chamber, the greater its ability to transmit torque (or speed); vice versa. When the external load is constant, the greater the liquid filling amount, the higher the efficiency, the greater the coupling starting torque and overload coefficient; and vice versa.
2) A fluid coupling of a given size has a specific power range, called its power band, corresponding to the fluid fill. The fill range is 40-80% of total volume. Below 40%, the coupling is uneconomical because its power-transmission capacity is not fully used; inadequate bearing lubrication also accelerates wear and can cause vibration and overheating. Above 80%, insufficient space remains in the working chamber for changes in fluid-flow pattern, impairing coupling characteristics and reducing overheating protection.
If the cavity is completely filled with liquid, not only will the characteristics deteriorate, but the liquid will heat and expand, causing seal failure or the hydraulic coupling housing to burst. For this reason, the infusion of the basis must not be mistaken, let alone complete.
(Source: Chemical Equipment and Machinery)