Butterfly valve

Abstract

The invention provides a butterfly valve, in which a valve element peripheral portion almost simultaneously abuts on protrusions of a seat ring. By gradually varying inclination of a pressure contact surface of the protrusion, the pressure contact surface in the vicinity of a valve shaft is sharply inclined, and the surface far from the valve shaft is gently inclined. The abutting portion of the pressure contact surface abutting on the peripheral portion of the valve element is expanded to an opening direction side more in a portion far from the valve shaft than in the vicinity of the valve shaft. The peripheral portion of the valve element almost simultaneously abuts on an abutting portions of protrusions of the peripheral portion of the valve element.

Description

(1) Technical field [0001] The invention relates to a butterfly valve which makes a valve body installed in a valve box rotate around a valve shaft so as to open, close and regulate the flow of the valve. (2) Background technology [0002] The general butterfly valve is to make the roughly disc-shaped valve body installed in the valve box rotate around the valve shaft passing through the diameter direction of the valve body, to open, close or adjust the flow of the valve, and on the inner peripheral surface of the valve box Install the seat ring made of rubber-like elastomer. When the valve is closed, the seat ring is crimped by the peripheral part of the valve body because the valve body rotates around the valve shaft so that the plate surface is perpendicular to the direction of the flow path (closing direction), thereby forming a seal between the inner peripheral surface of the valve box and the valve body. [0003] Figure 8 An example of this seat ring is shown. The c...

AI Technical Summary

Problems solved by technology

[0011] However, even if the ridge near the valve shaft is under pressure to a certain extent, sealing cannot be achieved until the peripheral portion of the valve body comes into contact with the ridge near the center. The crimping of the protruding strip near the valve shaft when the center is in contact still cannot promote sealing, so that the torque when the valve is closed becomes the main cause of the large useless torque

[0012] In addition, when the valve body rotates in the closing direction to reduce the flow rate, since the peripheral portion of the valve body is likely to come into contact with the protruding strip near the valve shaft, there is also the possibility of deterioration of the seat ring at this portion.

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