JP2011064233A - Valve stem supporting structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steam valve supporting structure having excellent wear resistance and high reliability, preventing leakage and easy in repair. <P>SOLUTION: A valve stem supporting structure includes a valve stem having a valve element for sealing fluid at the end thereof and a cylindrical bush which is fixed to the inner face of casing having a valve seat for contacting with the valve element and contacts the valve stem at the inner face. The welded shape of Stellite on a bush inner face is formed in a bar shape in the longitudinal direction. Material of satisfactory machinability is applied to portions of the Stellite inner face where Stellite is not applied. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a main steam valve and a steam control valve, and more particularly to a steam valve support structure including a valve rod and a bush.

  FIG. 4 shows a general cross-sectional view of the steam valve. The steam valve comprises a valve body 7, a valve stem 2 having the valve body 7 at its end, a valve seat 6 in contact with the valve body 7, a bush 1 containing the valve stem 2, and a casing 5 containing the bush 1. The valve stem 2 reciprocates inside the bush 1 to change the flow path area by controlling the amount of steam by bringing the valve body 7 into contact with the valve seat 6 or separating it from the valve seat 6.

  Although it is necessary to prevent steam leakage between the bush 1 and the valve stem 2, sliding wear may occur at the contact surface between the bush 1 and the valve stem 2 if the gap is excessively small. Further, when the valve stem 2 is excited by the pressure fluctuation generated in the high-temperature and high-pressure steam, there is a possibility that tapping wear occurs at the contact surface between the bush 1 and the valve stem 2.

  For this reason, conventionally, a structure has been employed in which stellite is applied to the inner surface of the bush by welding to prevent wear in a high-temperature steam environment. However, there is a concern about damage due to stellite due to residual stress accompanying welding.

  As a conventional countermeasure example, a structure in which the bush 1 is formed of a ring-shaped member and the valve stem 2 is included has been employed as disclosed in Patent Document 1 (Japanese Patent Laid-Open No. 60-81404). However, there is a concern about wear on the contact surfaces that occurs between the ring-shaped members due to the divided structure, and an increase in the cost due to an increase in the number of parts can be a problem.

  In the future, steam pressure and steam temperature are expected to rise further to improve performance.

JP 60-81404 A

  An object of the present invention is to provide a steam valve support structure that is excellent in wear resistance, highly reliable, can prevent leakage, and can be easily repaired.

  In order to achieve the above object, the first valve stem support structure of the present invention is fixed to the inner surface of a casing having a valve stem having a valve body for sealing a fluid at its end and a valve seat in contact with the valve body. The cylindrical bush is in contact with the valve stem on the inner surface.

  Moreover, the welding construction shape of the bush inner surface stellite is made into a rod shape in the longitudinal direction, and by reducing the welding construction range of the stellite, residual stress is suppressed and damage is suppressed. In addition, a material with good machinability is applied to the inner surface of the bush where no stellite is applied, and the minimum clearance is passively secured by cutting according to the movement and deformation of the valve stem during operation. The feature is that the amount of leakage can be minimized.

  According to the present invention, residual stress is suppressed by reducing the stellite welding range, and reduction of damage can be expected. In addition, by applying a material having good machinability to a portion of the inner surface of the stellite where the stellite is not applied, a minimum gap during operation is passively secured and the amount of leaked steam can be suppressed.

  Further, the welded work shape of the bush inner surface stellite is made a rod shape in the longitudinal direction, and the welding process range of the stellite is reduced, so that residual stress is suppressed and damage can be expected.

  Moreover, it becomes possible to passively secure the minimum gap during operation by applying a material having good machinability to a portion where the stellite on the inner surface of the bush is not applied.

It is a figure which shows the Example of this invention seen from the arrow parallel to the axial direction. It is a figure which shows the Example of this invention looked at by the arrow at right angles to the axial direction. It is a figure which shows the example of arrangement | positioning of a bush and rod-shaped stellite. It is a figure which shows the conventional valve stem support structure. It is a figure which shows the Example of this invention which provided the ring-shaped member in the both ends looked at by the arrow perpendicular to the axial direction. It is a figure which shows the example of arrangement | positioning at the time of providing a ring-shaped member in a bush, rod-shaped stellite, and both ends. It is a figure which shows the Example of this invention which provided the one ring-shaped member in the arbitrary positions which looked at the arrow perpendicular to the axial direction. It is a figure which shows the example of arrangement | positioning at the time of providing a ring-shaped member in a bush, rod-shaped stellite, and arbitrary positions. It is a figure which shows the other Example of this invention seen from the arrow in parallel with the axial direction. It is a figure which shows the example of arrangement | positioning of the rod-shaped stellite which has a bush and the convex implantation part in an edge part. It is a figure which shows the example of arrangement | positioning at the time of providing a rod-shaped stellite which has a convex implantation part in a bush and an edge part, and a ring-shaped member in both ends. It is a figure which shows the example of arrangement | positioning at the time of providing the rod-shaped stellite which has a convex implantation part in a bush and an edge part, and a ring-shaped member in arbitrary positions.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a view showing a cross-section perpendicular to the longitudinal direction of a valve stem support structure that best represents the features of the present invention as Embodiment 1 of the present invention. As shown in FIG. 1, a rod-shaped stellite 3 is applied in the longitudinal direction of the inner surface of the bush 1, and the valve rod 2 is included inside. Further, a material 4 having good machinability is applied to a portion of the inner surface of the bush 1 where the stellite 3 is not applied, and the material is cut according to the movement / deformation of the valve stem 2 during operation so that a minimum gap is obtained. It is ensured passively and can minimize the amount of leakage.

  2 and 3 are other views showing a valve stem support structure that best represents the features of the present invention as the first embodiment of the present invention. As shown in the figure, a rod-shaped stellite 3 is constructed in the longitudinal direction on the inner surface of the bush 1, and the stellite constructed in the longitudinal direction on the inner surface of the bush 1 is continuous or intermittent. May be.

  FIG. 5 and FIG. 6 are other views showing a valve stem support structure that best represents the features of the present invention as the second embodiment of the present invention. As shown in the drawing, a rod-shaped stellite 3 is applied to the inner surface of the bush 1 in the longitudinal direction, and the valve rod 2 is included inside. Further, a material 4 having good machinability is applied to a portion of the inner surface of the bush 1 where the stellite 3 is not applied, and the material is cut according to the movement / deformation of the valve stem 2 during operation so that a minimum gap is obtained. It is ensured passively and can minimize the amount of leakage. Here, when importance is attached to leakage prevention, ring-shaped members 8 made of a material having excellent wear resistance such as stellite may be disposed at both ends of the rod-shaped stellite 3.

  7 and 8 are other views showing a valve stem support structure that best represents the features of the present invention as the third embodiment of the present invention. As shown in the drawing, a rod-shaped stellite 3 is applied to the inner surface of the bush 1 in the longitudinal direction, and the valve rod 2 is included inside. Further, a material 4 having good machinability is applied to a portion of the inner surface of the bush 1 where the stellite 3 is not applied, and the material is cut according to the movement / deformation of the valve stem 2 during operation so that a minimum gap is obtained. It is ensured passively and can minimize the amount of leakage. Here, when emphasizing leakage prevention, a ring-shaped member 8 made of a material having excellent wear resistance such as stellite is disposed at one end of the bar-shaped stellite 3 or inside the intermittent stellite 3. May be.

  FIG. 9 is a diagram showing a cross-section perpendicular to the longitudinal direction of the valve stem support structure that best represents the features of the present invention as the fourth embodiment of the present invention. As shown in FIG. 9, a rod-like stellite 9 having a convex implantation portion at the end is incorporated in a groove provided on the inner surface of the bush 1, and the valve rod 2 is included inside. Further, a material 4 having good machinability is applied to a portion of the inner surface of the bush 1 where the stellite 3 is not incorporated, and the material is cut according to the movement / deformation of the valve stem 2 during operation so that a minimum gap is obtained. It is ensured passively and can minimize the amount of leakage.

  FIG. 10 is another view showing a valve stem support structure that best represents the features of the present invention as the fourth embodiment of the present invention. As shown in the figure, a rod-like stellite 9 having a convex implantation part at the end is incorporated in a groove provided on the inner surface of the bush 1, and further a projection having a convex implantation part at the end. The rod-shaped stellite 9 may be continuous or intermittent.

  FIG. 11 is another view showing a valve stem support structure that best represents the features of the present invention as the fifth embodiment of the present invention. As shown in the figure, a rod-like stellite 9 having a convex implantation part at the end is incorporated in a groove provided on the inner surface of the bush 1, and further a projection having a convex implantation part at the end. The rod-shaped stellite 9 may be continuous or intermittent. Here, when importance is attached to leakage prevention, a ring-shaped member 8 made of a material having excellent wear resistance, such as stellite, is provided at both ends of the rod-shaped stellite 9 in the longitudinal direction having convex implantation portions at the ends. It may be arranged.

  FIG. 12 is another view showing a valve stem support structure that best represents the features of the present invention as the sixth embodiment of the present invention. As shown in the figure, a rod-like stellite 9 having a convex implantation part at the end is incorporated in a groove provided on the inner surface of the bush 1, and further a projection having a convex implantation part at the end. The rod-shaped stellite 9 may be continuous or intermittent. Here, when emphasizing the prevention of leakage, a ring-shaped member 8 made of a material having excellent wear resistance, such as stellite, has one end of a rod-shaped stellite 9 having a convex implantation portion at the end. You may arrange | position in the inside of the bar-shaped stellite 9 which has a convex implantation part in an edge part or an edge part, and is intermittent in the longitudinal direction.

  In Examples 4, 5 and 6 described above, a hard film such as CrC is applied to the inner surface of the casing 5 to prevent wear due to contact with the rod-shaped stellite in the longitudinal direction having a convex implantation portion at the end. You may do it.

  In the above embodiment, the stellite may be applied by welding or spraying. The material having good machinability may be a felt-like alloy made of FeCrAlY or a porous alloy having excellent corrosion resistance such as FeCrAlY.

  Furthermore, in the above embodiment, the sum of the thermal deformation amount of the stellite during operation and the initial gap amount is made smaller than the thermal deformation of the material with good machinability, so that the material with good machinability at the first operation can be obtained. Cutting powder can be prevented from entering between the stellite and the valve stem, and after cutting, the cutting powder can be secured in the gap formed between the material having good machinability and the valve stem.

DESCRIPTION OF SYMBOLS 1 Bush 2 Valve stem 3 Bar-shaped stellite 4 Abradable material 5 with good machinability Casing 6 Valve seat 7 Valve body 8 Ring-shaped member 9 Convex-shaped implantation part

Claims (6)

  In a valve stem support structure comprising a valve stem having a valve body that seals fluid at the end, and a cylindrical bush that is fixed to the inner surface of a casing having a valve seat that contacts the valve body, and that contacts the valve stem with the inner surface, A valve stem support structure characterized in that stellite is formed in a rod shape in the longitudinal direction on the inner surface of the bush.   In a valve stem support structure consisting of a cylindrical bush that is fixed to the inner surface of a casing having a valve body that seals a fluid at its end and a valve seat having a valve seat that contacts the valve body, A valve stem support structure characterized in that a rod-shaped stellite having a convex implantation portion at an end portion is incorporated in a groove capable of accommodating the implantation portion provided on the inner surface of the bush.   3. The valve stem support structure according to claim 2, wherein a CrC film is applied to the inner surface of the casing.   4. The valve stem support structure according to claim 1, wherein a material with good machinability is applied to a portion of the bush inner surface where no stellite is applied.   The valve stem support structure according to any one of claims 1 to 4, wherein the rod-shaped stellite is divided into a plurality of portions in the axial direction.   6. The valve stem support structure according to claim 1, wherein at least one ring-shaped member is provided on an inner surface of the bush.

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