Variable eccentric hard sealing butterfly valve

Abstract

The invention discloses a variable eccentric hard sealing butterfly valve which comprises a butterfly plate, a sealing ring, a valve body, a valve rod and a valve seat. The variable-eccentricity hard sealing butterfly valve is provided with a first eccentricity, a second eccentricity and a third eccentricity, wherein the first eccentricity is that the valve rod central axis of the valve rod deviates from the central plane of the sealing ring; the second eccentricity is that the valve rod central axis of the valve rod deviates from the central axis of the valve body runner hole; the projection of the central axis of the valve seat sealing conical surface and the projection of the central axis of the valve body runner hole on the section passing through the central axis of the valve rod and the central axis of the valve body runner hole coincide, and an eccentric angle is formed between the projections on the section perpendicular to the central axis of the valve rod and passing through the central axis of the valve body runner hole. The center face of the sealing ring is a plane passing through the thickness center of the sealing ring, and the sealing ring is a variable-eccentricity arc sealing ring. On the basis that the sealing performance is improved, the opening and closing torque of the valve is reduced, the machining precision is reduced, and therefore hard sealing butterfly valves with the two-way sealing requirement can be produced in batches through the cambered-surface-to-conical-surface sealing structure.

Description

technical field [0001] The invention relates to the technical field of butterfly valves, in particular to a variable eccentric hard-sealed butterfly valve. Background technique [0002] Traditional hard seal butterfly valves are mostly fixed eccentricity. Traditional hard-sealed butterfly valves are divided into double-eccentric hard-sealed butterfly valves and triple-eccentric hard-sealed butterfly valves. [0003] The double eccentric hard seal butterfly valve has the first eccentricity in which the center of the valve stem deviates from the center of the sealing surface, that is, the second eccentricity in which the center of the valve stem deviates from the center of the flow channel. This double eccentric butterfly valve is completely sealed by means of medium thrust, so it is The sealing direction is beneficial to achieve sealing, but when the sealing direction is unfavorable, the medium promotes the sealing surface to fall off, which makes the sealing invalid. Theref...

AI Technical Summary

Problems solved by technology

[0003] The double eccentric hard seal butterfly valve has the first eccentricity in which the center of the valve stem deviates from the center of the sealing surface, that is, the second eccentricity in which the center of the valve stem deviates from the center of the flow channel. This double eccentric butterfly valve is completely sealed by means of medium thrust, so it is The sealing direction is beneficial to achieve sealing, but when the sealing direction is unfavorable, the medium promotes the sealing surface to fall off, which makes the sealing invalid. Therefore, most of these double eccentric hard-sealed butterfly valves can only be used for one-way sealing, and it is difficult to achieve two-way full pressure difference. seal

[0004] The triple eccentric hard-sealed butterfly valve has a first eccentricity in which the center of the valve stem deviates from the center plane of the sealing surface, a second eccentricity in which the center of the valve stem deviates from the center of the flow passage hole of the valve body, and the centerline of the sealing surface and the valve body flow The third eccentricity of the angular offset between the centerlines of the channel holes, the seat and sealing ring of the triple eccentric hard-sealed butterfly valve obtain a quasi-elliptical sealing surface after obliquely cutting through the cone, which is the contact seal between the surfaces. Although this structure can realize two-way sealing, it requires particularly high machining accuracy, and it is very difficult to achieve full-pressure two-way hard sealing. Often, it is necessary to reduce the working pressure when sealing in reverse.

[0005] In addition, when the medium flows in from the stem side of the ordinary butterfly valve, the butterfly plate and related components are pushed to press against the valve seat to achieve a one-way seal. When the medium flows in from the opposite direction, the butterfly plate is pushed from the sealing ring by the medium Therefore, most hard-sealed butterfly valves have poor reverse sealing performance, and generally cannot achieve reverse full pressure differential sealing.

[0006] Ordinary hard-sealed butterfly valves are face-to-face seals. Impurities will inevitably be embedded in the contact surfaces of the two faces, which will cause the sealing surfaces to fail to fit completely and cause seal failure.

[0007] Ordinary hard-sealed butterfly valves are in contact with two conical surfaces. The sealing surface is wide and requires high sealing pressure. At the same time, in order to prevent the butterfly valve sealing ring from interfering with the sealing cone surface of the valve seat, the eccentricity of the valve stem is relatively large, so the opening and closing torque of the valve also increases. Big

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