Automatic adjustment of mechanical seal air film seal-

Automatic adjustment of mechanical seal air film seal

　2017-10-25　　

The automatic adjustment of mechanical seal air film seal:

The gap between the end face of the gas film seal and the gas film pressure distribution of the mechanical seal can be automatically adjusted, as shown in Figure 3-6. The groove structure is not considered in the analysis process.

Figure 3-6 Control Principle of Mixed Membrane

In the above figure, figure (a) shows the film pressure distribution curve of the sealing end face gap under the condition of zero speed and he gap. The static pressure of the gas film and the closing force are balanced, and the gas flows forward through the groove and the gap. Expanding in the radial direction makes the gas film pressure drop from P1 to atmospheric pressure P2. In the process of gas flow, because the resistance of the groove area flowing through the large gap is very small, the pressure drop of the gas film is very small, and most of the pressure drop occurs in the ungrooved sealing dam area.

Figure (b) shows the film pressure distribution curve of the seal end face gap when the shaft rotates and the shaft stops rotating. When the shaft rotates, the gas is sent to the end of the groove to generate additional hydrodynamic pressure. The pressure distribution curve changes and moves upward from the equilibrium position. At this time, the forces acting on the compensation ring are no longer balanced. In fact, the compensation ring will The film pressure distribution curve when the gap is increased from to to know to restore equilibrium; at this time, if the shaft stops rotating, the fluid dynamic pressure effect disappears, and the pressure distribution will decrease from the equilibrium pressure, which will cause the compensation ring to move in the axial direction. The gap is reduced from h to h0.

From the above analysis, we can see the inherent characteristics of air film seal. As long as the seal end face is non-contact and the total closing force remains unchanged, the end face average film pressure will also remain unchanged; on the other hand, when the average air film thickness does change This can be reflected in the changes in leakage.

Small metal bellows mechanical seal 　　583.html,

The working principle of mechanical seal gas film seal (2) 　　 gas film stiffness of gas film seal