How much do you know about the non contact seal bearing?

non contact seal bearing is a seal in which the seal does not contact the bearing parts that move relative to the seal, and there is a proper gap in the middle. This kind of sealing form hardly generates frictional heat during the rotation of the bearing, and the sealing cover is not abraded. This form is suitable for high-speed and high-temperature working environments. The smaller the gap of the non-contact seal, the better. There are three ways of non-contact sealing:

1. Gap sealing

The gap seal is to leave a small annular gap between the shaft and the bearing cover through hole, the radius gap is 0.1-0.3mm, the longer the gap, the smaller the sealing effect is. In order to improve the sealing effect, a plurality of side-by-side annular grooves can be opened in the bearing cover hole, and the grooves can be filled with grease. If it is used for lubricating oil sealing, a thread groove can be made on the hole wall of the bearing cap. The lubricating oil to be leaked out is sent back into the non contact seal bearing due to the screw conveying effect. The direction of the thread groove must be determined according to the rotation of the shaft. 

2. Oil slinging ring seal

During oil lubrication, the centrifugal force of the oil slinger ring on the shaft can throw the oil leaking along the axial gap into the groove of the bearing cover, and flow back to the bearing or oil pool through the oil return hole. The sealing effect is quite reliable. In order to produce the necessary The centrifugal force, the circumferential speed of the journal should not be lower than 5-6m/s, and the slinger ring is also often used to isolate the grease in the non contact seal bearing and the lubricating oil in the box.

3. Labyrinth seal

The basic principle of this kind of seal is to form a section of flow channel with great flow resistance at the seal. Structurally, a small tortuous gap is formed between the stationary part and the rotating part, forming a "labyrinth". If the "labyrinth" is radial, the axial size is compact, but the radial size is larger. If the "labyrinth" is axial, the radial dimension is compact, but the non contact seal bearing cover should be split, and the axial clearance should be larger to avoid jamming due to thermal deformation of the shaft. The labyrinth seal is quite reliable for both lubricating oil and bone grease, and the higher the speed, the better the effect.

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