JP2020159479A - valve - Google Patents

Abstract

To provide a valve that has a stem with a valve element and can suppress leakage of a fluid along the axis of the stem.SOLUTION: A valve 1 includes a valve body 2 having a fluid inflow passage 23, an outflow passage 24 and a valve seat 25 formed between these passages, and a stem 5 having at the tip thereof a valve element 3 that contacts with and separates from the valve seat 25 to open and close the passage, in which the stem is inserted through a bonnet 6 formed on or installed to the valve body 2. A packing 62 is externally fitted on the stem 5, and there are provided annular members 63, 64 made of metal, through which the stem 5 is inserted and which abut on the upper and lower end faces of the packing 62. A resin coating layer 65 for sliding with the outer peripheral surface of the stem 5 is provided at least on the inner peripheral surface side of the annular members 63, 64, and clearances between the outer peripheral surfaces of the annular members 63, 64 and the inner peripheral surface of the bonnet 6 are substantially zero.SELECTED DRAWING: Figure 1

Description

The present invention relates to a valve.

As the valve for fluid control, those having various mechanisms are used. Various types of stems with a valve body at the tip are used, such as those that perform helical motion, those that perform rotary motion, and those that perform reciprocating motion.

Since these stems move in various ways, the fluid flowing through the fluid passage in the valve body should not flow out from the gap between the outer peripheral surface of the stem and the inner peripheral surface of the valve body or bonnet cavity in contact with the stem. Also equipped with an O-ring and gland packing.

In valves that handle high-pressure fluid, these O-rings and gland packings are sandwiched at the top and bottom by metal annular members, and by pressing the annular members in the axial direction of the stem, the O-rings and gland packings are pressed into the stem. Compress in the axial direction of the stem and expand it in the lateral direction perpendicular to the axis of the stem, and bring the outer peripheral surface of the stem and the inner surface of the valve body or bonnet cavity into close contact with the O-ring and gland packing to prevent fluid from leaking to the outside. Is sealed.

In the valve described in Patent Document 1, the lower surface side of the gland packing 1 is sandwiched by a metal hammer 4, and the upper surface side is sandwiched by a metal packing retainer 5. In the valve described in Patent Document 2, the lower surface side and the upper surface side of the gland packing 84 are sandwiched by a metal hammer 85.

JP-A-2007-78003 JP-A-2018-96473

The Hameva 4 and packing retainer 5 in Patent Document 1 and the Hameva 85 in Patent Document 2 are made of a metal material, and the stem is damaged when rubbed against the metal stem. If the stem is scratched, fluid will leak in the axial direction of the stem, so to prevent the stem from being scratched, there is usually a diameter gap of about 0.2 to 0.3 mm between the stem and the stem. (Clearance) is provided.

Due to the existence of this gap, for example, in a valve in which gland packing is used, the gland packing is formed into an annular protrusion along the circumference of the inner and outer circumferences due to aging of a high-pressure load, and this protrusion is a gap. It enters, the lateral expansion of the gland packing is reduced, the surface pressure on the stem or the like is reduced, and the sealing property is lowered.

In order to suppress the formation of such protrusions, it is necessary to make the gap between the stem and the stem as small as possible, but if the gap is made small, the possibility of scratches on the stem increases, and the sealing property is improved. There is a risk of deterioration.

FIG. 6 shows a conventional valve in which the stem 5 is inserted through the annular gland packing 62. An annular metal Hamewa 63 is provided on the upper and lower end surfaces of the gland packing 62. The lower Hameva 63 is arranged on the lower surface of the columnar recess formed in the bonnet 6, and the upper surface of the upper Hameva 63 is brought into close contact with the upper surface of the recess of the bonnet nut 61 and cut inside the bonnet nut 61. The gland packing 62 is pressed in the axial direction of the stem 5 by the screwing of the female screw and the male screw cut on the outer circumference of the bonnet 61, whereby the gland packing 62 expands in the radial direction and the outer circumference of the stem 5 is formed. The surface and the inner peripheral surface of the gland packing 62 are in close contact with each other to prevent fluid leakage. Further, the gland packing 62 and the inner peripheral surface of the internal recess of the bonnet 6 are in close contact with each other to prevent fluid from leaking.

The gland packing of FIG. 6 has a three-layer structure so as to withstand high pressure. In the center of the three-layer structure, a resin packing ring 62a and the upper and lower surfaces of the packing ring 62a are sandwiched between a hard packing ring 62b using a resin having a hardness higher than that of the packing ring 62a. With such a structure, high sealing performance and high opening / closing durability can be ensured even when the pressure of the fluid becomes high.

In the valve shown in FIG. 6, the inner peripheral surface of the annular member (Hamewa) 63 and the outer peripheral surface of the stem 5 and the outer peripheral surface of the annular member (Hamewa) 63 and the inner peripheral surface of the recess inside the bonnet 6 There is a gap 66 between them.

FIG. 7 shows the state of the valve of FIG. 6 after aging. Even if the hard packing ring 62b has a hardness higher than that of the packing ring 62a, since it is made of resin, if it is continuously compressed by the bonnet nut 61 and the high-pressure fluid, the outer circumference and the inner side of the hard packing ring 62b are shown in FIG. An annular protrusion 67 may be generated on the peripheral edge. When the protrusion 67 is generated, the lateral surface pressure of the gland packing 62 may decrease and the sealing property may be deteriorated, which may cause fluid leakage.

An object of the present invention is to provide a valve having a stem having a valve body, which can suppress fluid leakage along the axis of the stem.

The present invention (1) comprises a valve body having a fluid inflow passage, an outflow passage, and a valve seat formed between these passages, and a valve body that opens and closes the passage by contacting and separating from the valve seat. A valve having a stem at the tip through which a bonnet formed or attached to the valve body is inserted, and the stem is prevented from leaking fluid from a gap between the stem and the bonnet. A packing for prevention is fitted on the outside, a metal annular member through which the stem is inserted and abutting on the upper and lower end surfaces of the packing is provided, and at least the inner peripheral surface side of the annular member is the outer peripheral surface of the stem. The valve is provided with a sliding resin coating layer, and the gap between the outer peripheral surface of the annular member and the inner peripheral surface of the bonnet is substantially zero.

In the valve of the present invention (1), a metal annular member that comes into contact with the upper and lower end surfaces of the packing is provided, and at least the inner peripheral surface side of the annular member is provided with a resin coating layer that slides on the outer peripheral surface of the stem. Has been done. The gap between the outer peripheral surface of the annular member and the inner peripheral surface of the bonnet is substantially zero. The inner peripheral surface of the annular member is resin-coated so as to slide with the outer peripheral surface of the stem, and the gap between the outer peripheral surface of the annular member and the inner peripheral surface of the bonnet is substantially zero, so that the gland packing is used. As a result of aging due to a high-pressure load, protrusions along the circumference of the inner and outer circumferences are not formed, and the surface pressure does not decrease due to lateral expansion of the gland packing. Therefore, the surface pressure between the stem and the like is not lowered, and the sealing property is not lowered.

The valve according to the present invention (2) is the valve according to the present invention (1), wherein the material of the resin coating layer is a fluororesin-based resin.

The present invention (2) is characterized in that the material of the resin coating layer is a fluororesin-based resin, which is excellent in heat resistance, chemical resistance, self-lubricating property, etc., and has a very small friction coefficient, so that the amount of wear is also large. Less, the valve has a longer life. As the fluororesin-based resin, a completely fluorinated resin, a partially fluorinated resin, or a fluororesin copolymer is preferable. The fully fluorinated resin includes polytetrafluoroethylene (PTFE) and the like, the partially fluorinated resin includes polyvinyl fluoride (PVF) and the like, and the fluororesin copolymer includes perfluoroalkoxy alkane resin (PFA). ).

The present invention (3) is the valve of the present invention (1) or (2) in which the packing is a gland packing. For valves that handle unspecified fluids, fluororesin-based resin gland packing is preferable to O-rings, and by combining gland packing and O-rings, it is possible to seal even ultra-high pressure fluids and valves. The life of the product can be further extended.

In a valve having a stem provided with a valve body, leakage of fluid along the axis of the stem can be suppressed, and the life of the valve can be extended as compared with a conventional valve.

Example 1 of the valve according to the present invention is shown. Example 2 of the valve according to the present invention is shown. A partial cross-sectional view of the vicinity of the gland packing used for the valve of the second embodiment is shown. The vertical sectional view of the gland packing of the three-layer structure used for the valve of Example 2 and inserted into a stem is shown. An enlarged cross-sectional view of a three-layered gland packing used for the valve of the second embodiment and inserted into the stem and a resin-coated annular member is shown. An enlarged cross-sectional view of a three-layer gland packing inserted into a stem and an annular member not coated with resin in a valve of the prior art is shown. In the valve shown in FIG. 6, an annular protrusion is formed around the gland packing due to aging.

Hereinafter, preferred embodiments of the present invention will be described in detail exemplarily with reference to the drawings. However, unless there is a specific description, the shapes of the components and their relative arrangements described in this embodiment are not intended to limit the scope of the present invention to them, but are merely explanatory examples. Further, for convenience, the directions of the members and the like may be referred to as up, down, left and right depending on the directions on the drawings, but these do not limit the scope of the present invention.

FIG. 1 shows valve 1 of Example 1 according to the present invention. This valve has four components, a valve body 2, an actuator 4, a yoke 7 and a bonnet 6 between them.

The valve body 2 is provided with an inflow port 21, an inflow passage 23, an outflow port 22, and an outflow passage 24, and a valve seat 25 is provided between the inflow passage 23 and the outflow passage 24. A valve body 3 having a contact surface that abuts and separates from the valve seat 25 is provided vertically, and the valve body 3 is formed on the lower tip side of the stem 5. The stem 5 is connected to the shaft 41, which is the shaft of the actuator 4, and is driven up and down by the actuator 4.

A bonnet 6 is attached to the upper portion of the valve body 2 by a bonnet nut 61, a yoke 7 is attached to the upper portion of the bonnet 6, and an actuator 4 is attached to the upper end portion of the yoke 7.

A through hole through which the stem 5 penetrates is formed inside the bonnet 6, and a gland packing 62 through which the stem 5 is inserted is provided in the through hole. The Hamewa 63 is provided on the lower surface side of the gland packing 62, and the O-ring holder 64 is provided on the upper surface side of the gland packing 62. The Hameva 63 and the O-ring holder 64 are made of metal, and the same coating layer as the fluororesin-based resin coating layer 65 shown in FIG. 3 is provided on the surface thereof. The resin coating layer 65 is in close contact with the outer peripheral surface of the stem 5 and the inner peripheral surface of the inner recess of the bonnet 6. As a result, the sealing property is ensured, and the aged deterioration of the gland packing 62 is reduced due to the aged use by opening and closing the high-pressure fluid. As the fluororesin-based resin, for example, PTFE or PFA is preferable.

FIG. 2 shows valve 1 of Example 2 according to the present invention. The valve largely has three components, a valve body 2, an actuator 4, and a bonnet 6 formed above the valve body 2 in between.

The valve body 2 is provided with an inflow port 21, an inflow passage 23, an outflow port 22, and an outflow passage 24, and a valve seat 25 is provided between the inflow passage 23 and the outflow passage 24. A valve body 3 having a contact surface that abuts and separates from the valve seat 25 is provided vertically, and the valve body 3 is formed on the lower tip side of the stem 5. The stem 5 is connected to the center of the actuator (handle) 4 and is driven up and down by the handle 4.

A through hole through which the stem 5 is inserted is formed inside the bonnet 6, and a gland packing 62 through which the stem 5 is inserted is provided in the through hole. Hamewers 63 are provided on the lower surface side and the upper surface side of the gland packing 62. The Hameva 63 is made of metal, and its surface is provided with a coating layer 65 made of a fluororesin-based resin (see FIG. 3). The resin coating layer 65 is in close contact with the outer peripheral surface of the stem 5 and the inner peripheral surface of the inner recess of the bonnet 6. As a result, the sealing property is ensured, and the aged deterioration of the gland packing 62 is reduced due to the aged use by opening and closing the high-pressure fluid. As the fluororesin-based resin, for example, PTFE or PFA is preferable.

FIG. 3 shows a partial cross-sectional view in the vicinity of the gland packing used for the valve of the second embodiment. Hamewers 63 are arranged on the upper and lower surfaces of the gland packing 62, and a fluororesin-based resin coating layer 65 is formed on the surface of the hammers 63. In FIG. 3, the resin coating layer 65 is formed on the entire surface of the Hameva 63, but it may be formed only on at least the inner peripheral surface. In that case, it is preferable that the gap between the Hameva 63 and the inner peripheral surface of the bonnet 6 is substantially zero so that there is no gap.

FIG. 4 shows a cross-sectional view of the gland packing 62 having a three-layer structure through which the stem 5 is inserted. A resin packing ring 62a is provided in the center of the three-layer structure, and the upper and lower surfaces of the packing ring 62a are sandwiched between hard packing rings 62b using a resin having a hardness higher than that of the packing ring 62a. With such a structure, high sealing performance and high opening / closing durability can be ensured even when the pressure of the fluid becomes high.

FIG. 5 shows an enlarged cross-sectional view of the gland packing 62 having a three-layer structure inserted into the stem 5 and the resin-coated Hameva 63 used for the valve 1 of the second embodiment. The gland packing 62 of the valve of FIG. 3 has a three-layer structure, the gland packing 62 itself is reinforced, and protrusions 67 do not occur on the inner and outer peripheral edges of the hard packing ring 62b, so that sealing performance is ensured and a high-pressure fluid is obtained. Aged deterioration of the gland packing 62 is reduced by aged use by opening and closing.

1; Valve 2; Valve body 3; Valve body 4; Actuator 5; Stem 6; Bonnet 7; York 21; Inlet 22; Outlet 23; Inflow passage 24; Outflow passage 25; Valve seat 41; Shaft 61; Bonnet nut 62; Gland packing 62a; Packing ring 62b; Hard packing ring 63; Saddle (annular member)
64; O-ring holder (annular member)
65; Resin coating layer 66; Gap (clearance)
67; protrusion

Claims (3)

A valve body having a fluid inflow passage, an outflow passage, and a valve seat formed between these passages, and a valve body having a valve body at the tip that opens and closes the passage in contact with and away from the valve seat. A valve with a stem through which a bonnet formed or attached to the body is inserted.
The stem is fitted with a packing that prevents fluid from leaking from the gap between the stem and the bonnet.
A metal annular member through which the stem is inserted and in contact with the upper and lower end surfaces of the packing is provided.
A resin coating layer that slides on the outer peripheral surface of the stem is provided on at least the inner peripheral surface side of the annular member, and a gap between the outer peripheral surface of the annular member and the inner peripheral surface of the bonnet is substantially provided. A valve characterized by being zero. The valve according to claim 1, wherein the material of the resin coating layer is a fluororesin-based resin. The valve according to claim 1 or 2, wherein the packing is a gland packing.

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