Working principle and characteristics of non-contact sealed rotary joint
The gap seal is ensured by a small mating gap between the relatively moving parts. There are several annular grooves in the piston (typically 0.5mmx0.5mm). Its function, on the one hand, can reduce the contact area between the piston and the hydraulic cylinder wall; on the other hand, it can evenly distribute the oil pressure in the groove, so that the piston is in the center position, reducing the side caused by the low accuracy of the parts. The friction caused by the pressure between the piston and the cylinder wall reduces leakage. The gap seal method has low frictional resistance, but poor sealing performance and high processing accuracy. Therefore, it is only suitable for occasions with small size, low pressure and high speed (working environment, medium). The gap between the piston and the cylinder wall is usually 0.02-0.05mm.
The characteristics of the gap seal are simple structure, low friction resistance and long service life, but it requires high processing accuracy of parts, it is difficult to completely eliminate leaks, the sealing effect is poor, the sealing performance cannot be improved with increasing pressure, and the mating surface is worn Cannot automatically compensate after. Therefore, the gap seal is only used for sealing between the cylinder bore and the piston with a small size, low pressure, and high speed of movement.