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What is the working principle of excavator hydraulic motor? What is the speed of the hydraulic motor?

2022-03-18

Excavator hydraulic motor is a device that converts the pressure energy of liquid into mechanical energy. In principle, a hydraulic pump can be used as a hydraulic motor, and a hydraulic motor can also be used as a hydraulic pump. But in fact, although the same type of hydraulic pump and hydraulic motor are similar in structure, there are some differences in structure due to their different working conditions.

①The hydraulic motor generally needs to rotate back and forth, so the internal structure should be symmetrical, while the hydraulic pump generally rotates in one direction, so there is no such requirement.

②In order to reduce the oil suction resistance and radial force, the size of the oil suction port of the hydraulic pump is larger than the size of the oil outlet port. However, the pressure in the low pressure chamber of the hydraulic motor is slightly higher than atmospheric pressure, so there is no such requirement.

③ The hydraulic motor needs to work normally in a wide speed range, so hydraulic bearings or hydrostatic bearings should be used. Because when the motor speed is very low, if the dynamic pressure bearing is used, it is difficult to form a lubricating sliding film.

④The vane pump relies on the centrifugal force generated by the high-speed rotation of the vane and the rotor, so that the vane always sticks to the inner surface of the stator, seals the oil, and forms a working volume. If used as a motor, a spring must be installed at the root of the vanes of the hydraulic motor to ensure that the vanes are always stuck to the inner surface of the stator so that the motor can start properly. logo.

②Start the mechanical efficiency. Refers to the actual output torque t of the hydraulic motor when it is started from a static state. and the theoretical torque t under the same working pressure difference. The starting mechanical efficiency of a hydraulic motor is an index to measure its starting performance. Since under the same pressure, the output torque of the hydraulic motor from standstill to the starting state of starting to rotate is greater than the output torque in operation, which makes it difficult to start the hydraulic motor under load, so the starting performance is very important for the hydraulic motor, starting Mechanical efficiency can just reflect its starting performance.

③ Speed. The rotational speed of the hydraulic motor depends on the flow rate of the supplied liquid and the displacement of the hydraulic motor itself. Due to the leakage inside the hydraulic motor, the liquid and objects entering the motor do not all push the hydraulic motor to do work, and a small part is lost due to leakage. Therefore, the actual speed of the hydraulic motor is lower than the theoretical speed.

④ Minimum stable speed. Refers to the minimum speed at which the hydraulic motor does not crawl under rated load. The so-called creeping phenomenon means that when the working speed of the hydraulic motor is too low, it cannot maintain a uniform speed, and it is in an unstable state of movement and stop when entering the human body.

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