Combined type padding structure

Abstract

A combined type padding structure is composed of upper padding, middle padding and lower padding. The shape of the cross section of the upper padding comprises an inverted right trapezoid and an inverted right triangle. The shape of the cross section of the middle padding comprises a triangle and a trapezoid. The shape of the cross section of the lower padding comprises an upright right trapezoid and an upright right triangle. The inner diameter parts and the outer diameter parts of the upper padding, the middle padding and the lower padding are provided with maze grooves. The combined type padding structure has the advantages that conical surface abutting structures between the padding can produce radial component force so that the upper padding, the middle padding and the lower padding can alternately compress the outer circumferential face of a valve rod and the inner circumferential face of a padding box, and the sealing performance of the valve rod is guaranteed; the inner diameter parts and the outer diameter parts are provided with the maze grooves, temperature and pressure can be gradually reduced when a medium flows through throttling clearance between sealing teeth and the valve rod in sequence and the expansion space formed by tooth grooves between the adjacent sealing teeth, and the sealing reliability is improved.

Description

Technical field [0001] The invention relates to a sealing structure at a valve stem, in particular to a sealing structure utilizing combined packing. Background technique [0002] The sealing packing at the existing valve stem is usually composed of several packings with a rectangular cross-section. The packing is pressed by the packing gland so that the inner peripheral surface of the packing hugs the outer peripheral surface of the valve stem, and the outer peripheral surface of the packing is pressed against the outer peripheral surface of the valve stem. Tighten the inner circumference of the stuffing box to form a sealed combination. With such a structure, the packing is only subjected to the vertical force given by the packing gland and the medium pressure. When the packing is lightly pressed, the packing seal is prone to medium leakage. When the packing is pressed too tightly, the contact surface between the valve stem and the packing is large. , the friction is larg...

AI Technical Summary

Problems solved by technology

With such a structure, the packing is only subjected to the vertical force given by the packing gland and the medium pressure. When the packing is lightly pressed, the packing seal is prone to medium leakage. When the packing is pressed too tightly, the contact surface between the valve stem and the packing is large. , the friction is large, and the valve opening and closing torque is large; at the same time, the inner peripheral surface of the existing sealing packing is a vertical plane structure, and the sealing specific pressure is small. When the medium pressure is high, the sealing is easy to fail, resulting in external leakage of the valve.

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