JPH08170737A - Gate valve - Google Patents

Abstract

PURPOSE: To flow a fluid to a valve chamber side through a seal part without damaging an elastic seal member by providing a releasable actuating device reducing contact pressure of a secondary seal loaded on a gate by a secondary seal assembly. CONSTITUTION: A secondary seal assembly structure can relieve contact pressure of a secondary seal at the time of opening and closing of a gate 15, and the pressure relief device is provided with a spring member 40 arranged between a seal support ring 31 and a space ring 38. The spring member 40 is allowed to have a spring constant selected in consideration of fluid pressure, so that when a seal retaining body 36 is pressurized and contacted on the gate 15 to form the secondary seal, a suitable contact pressure is continually kept between the seal retaining body 36 and the gate 15. However, when pressure more than a prescribed degree is applied on the seal retaining body 36 by the fluid pressure of an upper stream side (a flow path 26 side), the spring member 40 is compressed, and if largely compressed, the seal retaining body 36 is separated from the gate 15 to prevent the breakdown of an elastic seal member 36a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION This invention relates to a gate valve,
More specifically, the present invention relates to a gate valve provided with an actuator that relieves and releases the contact pressure of a secondary seal.

[0002]

Gate valves have been in common use for many years, for example in the petroleum industry for oil and / or
It is also used in various equipment such as gas equipment. However, such conventional gate valves are designed for installations with pressures of only a few thousand psi and today, due to exhaustion of energy sources, 30,000
It has become necessary to search for and produce oil and gas under very high pressures in the range of 00 psi (2,110 kg / cm ² ) or higher. The use of such high pressure has made it necessary to further enhance the sealing performance and safety of the valve.

A conventional gate valve is usually composed of a valve body having an inlet passage, an outlet passage, and a valve chamber therebetween, and a gate. The gate having the through hole is provided between the valve seats on both sides mounted in the valve chamber and is mounted on the valve stem. The valve chamber is closed by a bonnet fixed to the valve body. The valve stem is attached to a reciprocating device for moving the gate between a closed position where the flow through the flow passage is blocked and an open position where the flow through the flow passage is opened, and reciprocates in the bonnet. Such valves are available from United States Nos. 3,538,938 and 3,696,83.
No. 1 is shown.

Next, as a sealing element in the valve, an O-ring as shown in US Pat. Nos. 2,957,492 and 3,348,567 and US Pat. No. 4,264,054 are shown. It is also known to seal between the valve seat and the valve body using such a non-extrusion seal. It is also known to provide an O-ring seal at the end of the valve seat that contacts the gate, as shown in US Pat. No. 3,696,831. United States Patent No. 3,057,6
No. 30 and No. 3,758,072, a seal ring is a combination of a highly elastic O-ring and a polytetrafluoride ethylene polymer known under the trade name "Teflon" or "nylon" or other low friction plastic ring. Formation is taught. Further, U.S. Pat. No. 3,103,366 uses a metal ring such as thin aluminum having a deformable plastic made of polytetrafluoroethylene inside, and the metal ring has a slight change in groove clearance. Teaches a construction which is self-contained and which prevents the plastic ring from protruding through the gap when pressurized.

Further, in order to withstand the high pressure of fluid, there is a type in which a primary seal made of metal and a secondary seal made of an elastic material are used together for the gate. That is, the metal sheet surrounding the flow path in the valve forms a metal-to-metal primary seal for the gate, and when the gate moves to the closed position, the elastic seal moves to the gate side to form a secondary seal for the gate. The composite seal structure designed to
United States of America 4,377,2 by the same inventor as the present application
No. 73. The secondary sealing element shown in this prior art is one elastic ring in which a portion on the gate side is narrowed from its inner and outer peripheral surfaces by a hard ring, and this elastic secondary sealing element is provided in a cam groove on the side surface of the gate. A seal support ring with a guided pin will pull towards the gate as it moves from the open to the closed position and release the secondary sealing element from the gate as the gate moves from the closed to the open position. And the structure. However, with only the structure shown here, the contact pressure of the secondary seal with respect to the gate changes drastically depending on the open position and closed position of the gate, which damages the elastic secondary seal element, and conversely the fluid seal does not work at all. there were.

[0006]

As discussed in US Pat. No. 4,377,273,
One of the problems often encountered with gate valves is that they may not properly form a seal between the gate and the valve seat. This improper sealing often causes gate valves to leak from the seal. In U.S. Pat. No. 4,377,273 by the same inventor of the present application, a double-sided two-way cam is used as a suitable seal for a gate valve to positively strengthen the contact of the seal member with the gate. Disclosed is a structure of a secondary seal made of an elastic material which is intended to be reduced or reduced. Thus, while the configuration disclosed in U.S. Pat. No. 4,377,273 appears to provide advantages in many applications, there may be additional improvements in primary and secondary seal configurations. Have been found. Especially under high pressure conditions, such as when there is a large pressure difference between the two sides of the gate during the formation of the secondary seal, or in the case of a secondary seal located downstream of the gate, the secondary seal often has considerable force. When the gate is pressed against the gate, the gate is moved in the opening direction, so that dragging occurs on the elastic secondary seal surface, and the abrasion of the elastic secondary seal significantly progresses. It also increases the force required to open the valve due to the additional frictional drag on the gate. In such cases, it is desirable to be able to adequately release the secondary seal prior to the gate moving substantially linearly across the sealing surface.

That is, it is not necessary for the secondary seal member to be completely pulled down from the gate, and when the gate is moved to open or close the valve, the contact pressure of the seal with respect to the gate is appropriately reduced, and the seal is substantially "inoperative". It is desirable for the pressurized fluid through the valve to flow rather rather between the seal and the gate to prevent wear.

Further, under the high pressure condition such as when the secondary seal is fully operating with almost no pressure inside the valve body, and then the pressure is applied from the upstream side, the fluid has such a function. It cannot enter the valve chamber in the main body unless it leaks from the secondary seal on the upstream side of the gate. Since the upstream secondary seal is mechanically activated, the operational state of the seal is maintained unless the pressure load of the fluid exceeds the mechanical force. However, in some cases, the fluid pressure becomes large enough to overcome the mechanical force of the seal and jet from the seal portion, and the elastic ring of the seal device may be broken.

Therefore, under the conditions as described above, a mechanism (for example, spring means) for gradually reducing and releasing the contact pressure from the secondary seal that receives the action of the pressurized fluid is provided so that when the fluid pressure reaches a predetermined value, It is desirable that the pressure rather pull the seal away from the gate to allow fluid to flow through the seal, eg to the valve chamber side, without damaging the resilient seal member. Next, in the primary seal provided on the flow path side in order to buffer the high fluid pressure directly acting on the secondary seal containing the elastic material from the flow path, the conventional valve seat has one tubular member made of metal. Since it is formed as, and the part far from the gate is press-fitted to the valve body, it is difficult to replace it, especially on site. A special tool is required to remove such a fitting sheet,
The fitting hole of the valve body and the fitting surface of the primary seat are damaged by prying between the two when they are removed. Therefore, it is desired to provide a primary valve seat in which only the gate side portion, which is easily worn, can be replaced without damaging the fitting surface between the primary seat and the main body.

[0010]

A gate valve of the present invention basically moves a valve body, a gate, a valve sheet for primary sealing, a secondary sealing device, and a secondary sealing device with respect to the gate. And a cooperating cam device for allowing the valve body to have a valve chamber closed inside by a bonnet and a pair of flow passages arranged in a straight line on both sides of the valve chamber. Is formed with a groove open to the valve chamber side around each inner end of the valve chamber, and the gate has a flow port for communicating the pair of flow channels and a non-hole portion for closing the flow channels. The valve seat is reciprocally movable between the gate positions where one end of the valve seat is connected to the valve stem and the valve opens and closes along a path that crosses the flow passage, and the valve seat is an inner end of the flow passage. Shape around An end surface of the tubular seat portion at the gate at each of the gate positions where the valve is opened and closed, having a portion fitted to a portion farther from the gate of each of the recessed grooves and a tubular seat portion located on the gate side of the portion. To form a primary seal, the secondary seal device having a secondary seal assembly slidably mounted on the circumferential surface of the tubular seat portion of the valve seat, and a cooperating cam device formed on the side surface of the gate. And a seal support ring that partially engages the cam and moves the secondary seal assembly toward the gate when the valve is closed, which solves the conventional problems. Therefore, an operating device capable of relieving and further releasing the contact pressure of the secondary seal with the secondary seal assembly against the gate is provided for the gate.

Further, the secondary seal assembly includes a ring-shaped seal holder slidably disposed in the open groove of the seal support ring surrounding the tubular portion of the valve seat, with respect to the tubular portion. An elastic seal ring held in contact with the tubular portion in the inner groove and a space ring adjacent to the seal ring are provided, and the seal holder is elastic in an annular groove formed on the end surface adjacent to the gate. The secondary sealing member is arranged so as to be able to contact the gate.

Here, the gate valve of the present invention firstly has a spring member having a predetermined spring constant as an urging member as an operating device characterizing the gate valve. The spring member is disposed between the seal support ring and the space ring and biases the elastic secondary seal member as the seal support ring moves relative to the gate by the cooperating cam device, and in some cases Reduces the contact pressure with the gate. Therefore, the strength of this spring member, that is, the spring constant, is such that the spring member appropriately expands and contracts against the pressure under the fluid pressure of a predetermined range flowing through the gate valve, so that the elastic secondary seal member and the gate are It is selected so that the contact pressure generated between them can be relaxed.

The gate valve then modifies the cooperating cam system as the second element of the actuating device. The cooperating cam device has a pin projecting from the inner surface of the extension of the seal support ring along the gate side surface and a cam edge provided on the gate side surface so as to be engageable with this pin. It is formed on each cam wedge slidably attached to the engagement groove provided along both sides, and these cam wedges are formed on the orthogonal member formed at the end of the valve stem at least in the axial direction of the stem. The gates are connected without play, and the gate is connected to the orthogonal member through a slot having a slight gap in the axial direction. When the gate is pulled by the stem and moved from the closed position to the open position through the actuator of this configuration, the cam wedge moves by the above-mentioned clearance prior to the gate, and first, the pin of the seal support ring is moved from the cam edge. It is released, and the contact pressure of the secondary seal on the gate is subsequently released.

Further, in the gate valve of the present invention, the valve seat can be constructed as a two-part composite type of a part fitted to the valve body and a part forming a primary seal in contact with the gate. It is possible to replace only the primary seal forming part that is apt to wear.

Finally, the gate valve of the present invention includes a simplified sealing device for application when the fluid pressure is not so high. This type has a spring member as an actuator that relieves the contact pressure of the gate of the secondary seal, but does not have a cooperating cam device. The metal valve seat has a portion fitted to a part of an annular step groove formed at the inner end of the flow passage of the valve body and a tubular portion extending toward the gate side, and opens and closes the valve. The end face of the tubular portion is contacted with the gate at each gate location to form a generally metal-to-metal primary seal. However, depending on the situation, an elastic material may be used for the contact surface with the gate. The secondary sealing device includes a secondary seal assembly axially slidably mounted about the tubular portion of the valve seat, the secondary seal assembly being axially mounted on an outer peripheral surface of the tubular portion of the valve seat. An annular secondary seal holder that is slidably fitted, an elastic secondary seal member that is press-fitted in an annular groove formed on the gate side end surface of the holder, and a secondary seal holder (140)
An annular spring member, which is mounted in an annular groove formed on the inner peripheral surface of the valve seat and contacts the tubular portion, has an annular spring member for pressing the secondary seal assembly toward the gate. It is characterized in that it is arranged between the end face of the next seal holder and the side opposite to the gate. In this case, it is also possible that the secondary seal holder has a pair of gate guides extending along the side surface of the gate on the end face on the gate side.

[0016]

The features of the gate valve improved by the present invention to solve the problems of the prior art are as described above. This gate valve has a double-sided parallel type gate connected to the inner end of the valve stem. The handle is operated to move the valve within the valve body between a closed position and an open position. At this time, the metal valve seats, which are disposed in the annular step grooves formed around the inner ends of the flow passages on both sides of the valve body, contact their inner end faces with the valve face of the gate to provide a metal-to-metal primary seal. Always formed. The contact surfaces of the primary valve seat and the gate are opposed to each other based on a general mechanical fitting tolerance, but they slide against each other when the gate opens and closes. There is. In the present invention, the valve seat is improved to the two-part type, and the half part near the worn part can be replaced locally.

Next, the seal holder in the secondary seal device that slides on the outer peripheral surface of the primary valve seat has an elastic seal ring between itself and the valve seat surface, and also has an annular secondary seal member on the end face on the gate side. . This secondary seal member is an elastic material, which normally completely seals the fluid in the flow path that is almost sealed by the metal-to-metal primary seal, and further seals the fluid through the valve chamber by the adhesion of the elastic material to the gate. Prevent leakage from the upstream side to the downstream side.
However, the elastic secondary seal member that forms a secondary seal with the gate is more susceptible to damage than metal due to sliding friction with the gate surface due to opening and closing of the valve. Therefore, even in the prior art, the seal holder is made movable by using the seal support ring that moves in the flow direction following the cam provided on the side surface of the gate, and the elastic secondary of the seal holder is mainly provided only when the gate closes the valve. The seal member was pressed against the gate sufficiently. However, when the gate is moved to the open position, the release of this pressure contact is delayed, a force is required to open the valve, abrasion of the secondary seal member cannot be sufficiently prevented, and the sealing property after release of pressure contact is not sufficient. There was a flaw that was sufficient.

In the present invention, in order to reduce the extreme pressure contact between the elastic secondary seal member and the gate, a new spring member is provided between the seal support ring and the secondary seal holder to provide a secondary seal. The contact pressure is not so strong that the elastic seal material is damaged, and the sealing property is appropriately maintained even when the pressure contact is released. In addition, in order to eliminate the delay in releasing the pressure contact when moving the gate to the open position, a separate cam wedge is mounted on the side surface of the gate so that it can move relatively, and a cam is provided on this wedge to move the gate from the valve closed position. When moved to the open position, the engagement structure between the three members has been improved so that the valve stem slightly moves the cam wedge prior to movement of the gate. Therefore, the seal support ring moves away from the gate as the cam wedge moves forward,
The elastic secondary seal member also tries to separate from the gate. However, in the present invention, due to the presence of the spring member, the secondary seal member is not completely separated from the gate, and is retracted while maintaining the sealing property under a proper contact pressure, during which the gate is elastically moved from the closed position to the open position. It is moved without damaging the secondary seal member.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The gate valve of the present invention is provided with a secondary seal assembly mainly in contact with an elastic material, in addition to a primary seal mainly in contact with the gate. This gate valve is described in the above-mentioned US Pat. No. 4,377,273.
Like the gate valve disclosed in the above publication, it is of a stem lifting type. The prior application of the same inventor, U.S. Pat. No. 4,377,273 (hereinafter also simply referred to as the same application of the same person), will be occasionally compared and referred to in the following description. It is a further improvement of the technical inadequacies.

Referring to FIGS. 1, 8A and 9A. The gate valve 10 has a valve body 11, and a valve chamber 12 is formed inside the valve body 11.
A bonnet (not shown) is attached to the upper portion of the gate valve 10, and the bonnet closes the upper end of the valve chamber 12 and seals between the valve body 11 and the stem 14.

The gate valve 10 has a gate 15 arranged in the valve chamber 12. In general, the gate 15 has a rectangular cross section, its two surfaces contacting the valve seats 28 and 131 are parallel to each other, and the upper portion thereof is connected to the stem 14. Therefore, the vertical movement of the stem 14 moves the gate 15 up and down. In this example, the stem 1
A stud 16 with a screw is formed at the lower end of 4. On the other hand, a screw hole 17 having a female screw is formed in a cylinder 18 that is fitted into a cylindrical hole 19 that laterally penetrates the upper portion of the gate 15, and the stud 1 is inserted into this hole 17.
6 is screwed. The stud 16 is the cylindrical portion 2 of the stem 14.
It is connected to 1. In addition, the cylindrical portion 21 is the gate 1
5 is inserted into the opening 20 on the upper surface. Further, a truncated cone portion 22 is formed on the stem 14 above the cylindrical portion 21. The truncated cone portion 22 acts as a stopper and contacts the lower surface of the bonnet (not shown) to limit the rise of the stem 14.

The vertical movement of the stem 14 can be accomplished by various methods. In this example, the stem 1
Reference numeral 4 is screwed into a yoke nut (not shown), and the rotation of the yoke nut moves the stem 14 in its longitudinal direction, and the gate 15 moves up and down in accordance with the movement. There are various other methods of connecting the stem 14 and the gate 15, and an improved example will be described later with reference to, for example, FIG.

As shown in the figure, the valve body 11 is formed with projecting portions 23 and 24 which project toward the valve chamber 12 so as to face each other. The protrusions 23 and 24 are formed in the valve body 1
1 inside the flow paths 25 and 26 (valve chamber 12
The side) is formed so as to surround the end. On the other hand, a flow port 15a is formed in the gate 15 so as to penetrate therethrough. The flow port 15a is set so as to be aligned with the flow paths 25 and 26 and to open the valve when the gate 15 rises.

An annular step groove 27 is concentrically formed on the protrusions 23 and 24 so as to face the flow paths 25 and 26. In the embodiment shown in FIGS. 1 and 3, a metal valve seat 28 is attached to the step groove 27. The valve seat 28 has a large-diameter portion 29 fitted to the valve body 11,
The outer annular end face contacts the valve face of the gate 15 and forms a metal-to-metal primary seal for the normally flowing fluid. The metal end surface of the primary seal prevents the fluid in the flow paths 25 and 26 from leaking into the valve chamber 12 and guides the vertical movement of the gate 15.

In the embodiment of FIGS. 8A, 9A and 9B, a slightly shorter valve seat body 128, also made of metal, is attached to the step groove 27. The valve seat body 128 has a ring-shaped seat surface member 131 screwed into the tubular portion 129 having a slightly smaller diameter. The inner flange surface of the metal seat surface member 131 is engaged with the outer end surface 132 of the tubular portion 129 of the valve seat body 128.
Forming a metal-to-metal interface between and. The tubular portion 1
The elastic seal member 133 is mounted in the annular space 138 formed between the sheet surface member 131 and the seat surface member 131, and the tubular portion 12
9 and the seat surface member 131 can be more reliably sealed. The annular space 138 is formed by the truncated cone surface 139 at the outer peripheral corner of the tubular portion 129. The end surface 134 of the seat surface member 131 engages the gate 15 to form a so-called primary metal-to-metal seal between them.

The seat surface member 135 shown in FIG. 8B can be used in place of the seat surface member 131 shown in FIG. 8A. An annular groove 136 is formed on the end surface of the seat surface member 135. An elastic seal ring 137 made of an elastic material such as rubber or Teflon is mounted in the groove 136 to form a good seal between the seat surface member 135, the gate 15 and the elastic seal ring 137. It This method does not require the precision of processing required for metal-to-metal seals to the gate, and for low pressure use, the primary seal plus the secondary seal assembly described below. You don't have to do it and the cost can be kept very low. 8A and 8B show, for reference, a simple configuration in which the secondary seal assembly is omitted. Of course, FIG. 8B
The structure of the primary seal with the elastic seal ring 137 shown in FIG. 9 can be adopted in the configurations of FIGS. 9A and 9B described later.

Incidentally, instead of the primary valve seat 28 made of one member as shown in FIGS. 1 and 3, FIG. 8A,
As shown in FIG. 9A and the like, the valve seat main body 128 fitted to the valve main body 11 is screwed to the seat surface member 131.
When the seat surface member 1 is detachably used, even if the end surface 134 that makes seal contact with the gate 15 is worn, the seat surface member 1
Only 31 can be removed from the threaded portion with the valve seat body 128 and easily replaced. This easy-to-replace configuration of the primary seal portion is an improvement over the earlier application of the same person.

Next, the secondary seal will be described. Figure 1,
As shown in FIG. 9A, the secondary seal, which is supplemented to the primary seal, has a seal support ring 31 for strengthening its contact pressure when the valve is closed, around the tubular portion 30 of the valve seat 28 of the primary seal (FIG. 1). Or the valve seat body 1
It is arranged around the 28 sheet surface members 131 (FIG. 9A). The seal support ring 31 is formed in the shape of a flanged ring and has an inward opening groove 37 at the end portion on the gate 15 side, so that its shape is L-shaped in cross section. Further, the seal support ring 31 has a pair of axially extending portions 32 and 33 on its side portions, and these extending portions 32 and 33 extend along both side surfaces of the gate 15, respectively. (Fig. 2
reference). Each extension 32, 33 has a short cylindrical pin 34. This pin 34 is the gate 1 of each extension 32, 33.
It is fixed to the inner flat surface along 5. On the other hand, the gate 15 has cam edges 35 on both sides thereof. Each cam edge 35 comprises a vertical portion 35a located at the lower end of the gate and an inclined portion 35b located above it. Pin 34
Is driven by engagement with the cam edge 35 to move the seal support ring 31 toward the gate 15. When the gate 15 is lowered to the closed position shown by the lowering of the stem 14, the pin 34 moves along the cam edge 35 from its position engaged with its vertical portion 35a to the position engaged with the inclined portion 35b, Both seal support rings 3
1 is drawn to the gate side. In the prior application U.S. Pat. No. 4,377,273 by the same inventor as the present application, a double-sided type having a front edge and a back edge for separating and contacting a secondary seal with respect to a gate with respect to the single-sided cam edge of the present application is disclosed. Was provided with a groove. This modification is related to the fact that the present invention newly provides an actuator capable of relieving the contact pressure of the secondary seal and further releasing it.

Further, referring to FIGS. 1 and 9A, the secondary seal assembly is mounted in the open groove 37 of the seal support ring 31. This secondary seal assembly includes a seal support ring 31 and a primary valve seat 28.
Alternatively, a metal seal holder 36 slidably supported between the seat surface member 131 is provided. The structure of this secondary seal assembly is different from the simple seal element in the previous application of the same person in which the elastic ring is sandwiched by the hard ring from the inner and outer circumferences, and the contact pressure of the secondary seal can be relaxed when the gate is opened and closed. Is.

The seal holder 36 is a stepped annular ring having an inner groove and is L-shaped in cross section. Further, the seal holder 36 has an annular elastic secondary seal member 36a attached to the annular groove on the end face on the gate side by press fitting or the like. In addition, the inner groove of the seal holder 36 is shown in FIGS.
As shown in B, the space ring 38 having a rectangular cross section and the elastic seal ring 3 which can be compressed are slidably arranged.
9 is equipped. Since this elastic seal ring 39 is compressively deformable, when it is compressed through the space ring 38, the seal ring 39 comes into close contact with the surrounding wall surface to form a sufficient internal seal. As the elastic seal ring 39,
For example, an O-ring having a circular cross section formed of a compressible elastic material can be used. In the embodiment shown in FIG. 10, the elastic seal ring 39 is a compressible elastic ring whose cross section is close to a rectangle, and includes a protrusion preventing member 50 at the corner portion.

In a more preferred embodiment, a pressure relief device for the seal holder 36 is provided. In the embodiment of FIGS. 1 and 9A, the pressure relief device includes a spring member 40 disposed between the seal support ring 31 and the space ring 38. Since a spring constant having a spring constant selected in consideration of fluid pressure is used as the spring member 40, when the seal holder 36 is pressed against the gate 15 to form a secondary seal, a proper contact pressure is constantly applied. Is maintained between the gate and. But upstream (Fig. 1,
When a predetermined or more pressure is applied to the seal holder 36 (more specifically, the elastic seal ring 39) by the fluid pressure in the flow path 26 side in FIG. 9A, the spring member 40 is compressed. When the spring member 40 is largely compressed, the seal holder 36 separates from the gate 15 and the elastic seal member 3
Prevent the destruction of 6a.

The spring constant of the spring member 40 is determined by the seal holder 36, the elastic seal ring 39, and the secondary seal member 36.
It is determined based on the constituent materials of a and their pressure resistance to the critical pressure. The choice of this spring constant is a design issue that can be determined by one of ordinary skill in the art based on the disclosure of the present invention.

The spring member 40 may be formed of a plurality of springs, and its spring constant may be arbitrarily changed according to the operating condition of the secondary seal. In the illustrated embodiment, the spring member 40 is a flat spring having a spring constant that can respond to a predetermined level of pressure. Note that this may be an O-ring seal.

Therefore, in the embodiment shown in FIGS. 1 and 9A, the presence of the spring member 40 serves as a buffer function for the upstream fluid pressure, and when the pressure is abnormally high, the seal holder 36 is quickly removed from the gate. It also has a release function to pull it apart.

Further, in the gate valve of the present invention, the above-described cam edge 3 directly engraved on both side surfaces of the gate 15 is provided.
Instead of 5, a cooperating cam device of the type using a separate cam wedge can be used. This cooperating cam device is shown in FIG.
Engagement groove 1 in the vertical direction near both sides of the gate as shown in
And a cam wedge 60 slidably fitted along 26. This cam wedge is set so that when the valve opens, it slightly moves up before the gate moves up. Therefore, the restriction of the cam edge with respect to the pin 34 of the seal support ring 31 is loosened, and then the secondary seal is loosened. The gate will move upward in the figure. 3 and 9B show a gate valve provided with the cam wedge 60. The terms "vertical" and "horizontal" used in the description of these figures refer to the valve illustrated in FIG. 3 or 9B. In the figures, the valve is shown upright with the stem 14 extending upwardly from its top. As shown in FIGS. 5 and 6, the cam wedge 60 is formed in a rectangular shape, and a notch 62 is formed in the lower portion thereof. Due to the notch 62, the one-sided cam edge 3
5 are formed symmetrically. The cam edge 35 has substantially the same shape and function as the cam edge 35 provided directly on both side surfaces of the gate 15 as shown in FIGS. 1 and 9A. The cam edge 35 is the lower vertical portion 35.
a and an upper inclined portion 35b. As described in the section of FIG. 1 and FIG. 9A, since the cam edge 35 is cam-engaged with the pin 34, when the gate 15 is lowered to the closed position by the lowering of the stem 14, the pin 34 is gently moved to the cam edge 35. From the vertical portion 35a to the inclined portion 35b
Move to. As a result, each seal support ring 31 integrated with the pin 34 is moved to the gate 15 side, and the contact pressure of the secondary seal is strengthened.

The cam wedge 60 has tabs 64 facing each other. Each of these tabs 64 extends outwards and the gate 1
5 is slidably engaged with an engagement groove 126 formed in the groove 5.
As a result, the cam wedge 60 is supported by the gate 15 and is relatively movable in the vertical direction (see FIGS. 3, 9B and 4). A horizontal slot 68 having a rectangular cross section is formed in the upper portion of the cam wedge 60. As will be described in more detail below, this slot 68 defines the orthogonal member 1 at the lower end of the stem 14.
It is formed so that 16 can be fitted.

As shown in FIGS. 3 and 9B, an extension portion 121 having a rectangular horizontal cross section is formed in the lower portion of the stem 14, and a rectangular parallelepiped orthogonal member 11 is formed at the lower end of the extension portion 121.
Since 6 is fixed, both form an inverted T-shaped block. Further, in this embodiment, the width of the orthogonal member 116 in the left-right horizontal direction is as shown in FIG.
It is set to be wider than the horizontal width of 21 and narrower than the horizontal width of the gate 15. In the direction perpendicular to the plane of the drawing, the horizontal length of the orthogonal member 116 is set to be longer than the horizontal length of the extension portion 121 and substantially equal to the horizontal length of the gate 15. Each lengthwise end of the orthogonal member 116 is formed for slidable engagement within a slot 68 (FIG. 6) of the cam wedge 60, but between these ends and the slot 68. Vertical play is minimal.

The gate 15 has vertical (up and down) slots 120 and horizontal (horizontal) slots 117 (see FIGS. 3 and 9).
(See B) and are formed. The extending portion 121 of the stem 14 and the orthogonal member 116 are engaged in the slots 120 and 117, respectively. In this case, the slot 120 is formed so as to slidably hold the extending portion 121 and minimize the lateral (left and right in the drawing) play of the gate 15 with respect to the stem 14. However, the dimension of the slot 117 provided in the gate 15 in the vertical (vertical) direction is set larger than the dimension of the orthogonal member 116 at the lower end of the stem in the vertical (vertical) direction.
The stem 14 can be vertically moved by a predetermined dimension (125 in the figure) corresponding to the difference without the gate 15 being vertically moved, and the cam wedges 60 on both sides of the gate are driven by the stem 14 at this time.

In this embodiment, the stem 14
To combine the gate 15 with the cam wedge 60,
It is necessary to set the length of the extending portion 121 of the stem 14 in the horizontal direction (right angle to the paper surface) to be shorter than that of the slot 120 of the gate 15 in the same horizontal direction, and to form a space between them.
The reason is that the stem 14 is moved to one side of the gate 15 and the wedge 60 is attached to the other side of the gate. This void is shown as a blank area in FIG. Such dimensional difference is not necessary for the horizontal (left and right in the drawing) width of the extending portion 121 of the stem. Further, the stem, gate and cam wedge can be combined with each other in a form different from the above.

When the cam wedge 60 constructed as described above is used, the gate valve 10 is closed (see FIGS. 3 and 9).
In the case of B), the seal support ring 31 is already drawn to the gate 15 by the lowering of the cam wedge 60, and the cam edge guides the pin 34, so that the secondary seal operates. When the gate valve 10 is opened, while the stem 14 is raised by a certain distance (125 in the drawing), the gate 15 is not raised and only the cam wedge 60 is pulled up as described above. This advance movement of the cam wedge 60 causes the edge 35 of the cam wedge 60 to slightly release the pin 34 along its upper ramp 35b (FIG. 6) before the gate 15 begins to rise, thereby contacting the secondary seal. The pressure is released, and abrasion of the elastic secondary seal member 36a due to sliding on the gate surface is effectively prevented.

When the gate is lowered by the stem 14 to close the valve, the frictional resistance of the primary seal members 28 and 131 against the gate 15 causes
The gate 15 tries to stop at the high position shown in FIGS. 3 and 9B. Further, if a stopper (not shown) is provided below the gate 15 and the lowering of the gate 15 is restricted by this stopper, the preceding movement of the cam wedge 60 can be performed when the stem 14 is raised. Therefore, wear of the secondary seal member 36a can be prevented.

In FIG. 6, the cam edge 35 whose upper portion is different from the cam edge 35 shown in FIGS. 1, 3, 9A and 9B is shown by a broken line. That is, the cam edge 35 shows an upper vertical portion 35c (broken line portion) which is directed upward in the middle of the conventional inclined portion 35b. Since the upper vertical portion 35c is formed in parallel with the valve surface of the gate 15, the pin 34 is attached to the upper vertical portion 3c.
Seal support ring 3 by engaging with 5c
The movement of 1 toward the gate 15 is smaller than that of the cam edge before modification, and therefore the secondary seal is not tightened more than a certain amount.

FIG. 7 shows a cam wedge in which the width of the cam wedge 60 shown in FIGS. 4 to 6 is changed. The cam wedge 60 positions the gate 15 at the center thereof so that the opposing secondary seals on both sides of the gate act uniformly. The horizontal cross-sectional shape of the cam wedge 60 in the case of FIG. 7 is basically the same as the horizontal cross-sectional shape of the cam wedge 60 of FIG. 4, but differs in the following points. That is, when the cam wedge 60 is mounted on the gate 15, gaps are formed between the tab 64 and the engaging groove 126 and between the cam wedge 60 and the gate 15, and the cam wedge 60 is indicated by an arrow with respect to the gate 15. It is a point that can move a little in the direction of 66.

Therefore, when the cam wedge 60 having a gap for moving in the lateral direction is attached to the gate 15 (see FIG. 7), the floating of the cam wedge 60 causes the gate 15 to oppose the secondary seal. The misalignment between the gaps is naturally compensated, and uniform secondary seals are formed on both surfaces of the gate 15.

Thus, in the embodiment shown in FIGS. 3 and 9B, the seal actuation mechanism associated with the cam wedge 60 relieves the contact pressure of the secondary seal prior to moving the gate from the closed position to the open position. Since it is possible to compensate for the misalignment between the gate and the seals on both sides, it is not necessary to forcibly provide the buffer spring member between the seal support ring 31 and the secondary seal holder 36. .

In the embodiment of FIG. 11, FIG. 3 and FIG. 9B
Unlike, the orthogonal member 116 at the lower end of the stem is engaged in the slot 117 'in the gate 15 without a gap, and the spring member 40 similar to that in FIGS. 1 and 9A is used. Since there is no gap, the vertical width of the slot 117 'and the thickness of the orthogonal member 116 are substantially the same. Also in this embodiment, the composite type primary sheets 128 and 131 can be used as in the case of FIGS. 9A and 9B.

In the embodiment shown in FIG. 11, the movement of the seal support ring 31 toward the gate 15 side is restricted so that the spring member 40 is not compressed beyond its elastic limit. The movement of the seal support ring 31 is limited by the axial length of the seal support ring 31 being longer than that in FIGS. 9A and 9B, and thus the inner end surface 153 of the seal support ring 31 contacts the gate 15. Also, in order to prevent the seal support ring 31 from abrading the surface of the gate 15, after the inner end surface 153 of the seal support ring 31 comes into contact with the gate 15, the stem 15 is prevented from further descending.
The descent has been adjusted. That is, the descent of gate 15 is limited by properly stopping the descent of stem 14. And this stop of the stem 14 is stopped by the stem 14
This is accomplished by mounting a stop nut 154 on the outer side of the and then threading it onto a stem nut 155 that regulates the position of the handle 157 with respect to the bonnet 156 so that the handle is properly secured. To adjust the screwing stop position of the stop nut 154 with respect to the stem nut 155, the seal support ring 31 is moved by the cam edge 35 of the cam wedge 60 via the pin 34 to the gate 15 of the seal support ring 31.
The inner end surface 153 and the surface of the gate 15 are brought into contact with each other and must be aligned. Stem 1
By limiting the descent of 4 the cam wedge 6
0, the seal support ring 31, the gate 15 and the stem 14 are also prevented from being overloaded.

Next, an embodiment using a simple seal assembly without a seal support ring will be described with reference to FIGS. 9C, 9D and 9E.

In FIG. 9C, a ring-shaped secondary seal holder 140 is axially slidably engaged with the tubular portion 149 of the valve seat 148. An annular elastic secondary seal member 140a is attached to the end surface 142 of the secondary seal holder 140 by press fitting or the like. The secondary seal holder 140 has an O-ring 140b in the inner groove 150. The O-ring 140b forms a seal with the outer peripheral surface of the tubular portion 149. Figure 9C
In the embodiment of FIG.
44 and the secondary seal holder 140 between the spring member 14
1 is provided. Further, in the embodiment of FIG. 9D, a ring-shaped convex portion 152 is formed on the outer periphery of the valve seat 148, and a pocket 145 for storing the spring member 141 is formed between the valve seat 148 and the secondary seal holder 140. This spring member 14
1, the end surface 142 of the elastic secondary seal member 140a is brought into contact with the gate 15. Further, when a strong pressure is applied to the secondary seal surface by the pressurized fluid from the upstream side, the spring member 141 is compressed and the secondary seal holder 140 is separated from the gate 15, so that the elastic secondary seal member 14
0a is not damaged. However, when the fluid pressure is within the predetermined range, the spring member 141 effectively acts to maintain the secondary seal.

In the embodiment of FIGS. 9C and 9D, the secondary seal holder 140 is provided with gate guides 143 (see FIG. 9E) extending along both side surfaces of the gate 15. These prevent rotation of the secondary seal holder 140 and lateral runout of the gate 15.

Although a spring is generally used as the spring member 141, an elastic O-ring or the like may be used.

Although the present invention has been described based on several embodiments, the detailed configurations may be combined with each other without departing from the scope of the invention. For example, by applying a cam wedge 60 separate from the gate to an embodiment of the spring member 40 as in FIGS. 1 and 9A, when moving the gate to open the valve, the gate 15 and the secondary seal member are It is also possible to more effectively relieve and release the contact pressure. Furthermore, a spring member may be applied to the embodiment of FIGS. 3 and 9B so that the secondary sealing device 36 is effectively retracted when the pressure of the fluid reaches a predetermined value or more. Further, in the embodiment of FIG. 9C, a two-member composite type valve seat mechanism can be used.

[0054]

According to the present invention, a primary seal member and an elastic secondary seal member are provided around the inner end of a fluid flow passage from both sides of a gate that moves in the valve body for opening and closing the valve. It is a gate valve of a type that keeps the liquid seal in the valve by concentrically contacting with each other.Mainly, it is necessary to relieve the contact pressure of the secondary seal and to provide an operating device for the gate that can be released. Characterize. The first of this actuator
As an element of the above, a spring member is provided behind the annular holding member of the elastic secondary seal member so that the secondary seal member is always biased toward the gate. Abut on the end face of the secondary seal holder regardless of the position of the seal support ring that is in contact with and is moved relative to the gate by a cam formed on the side surface of the gate when the gate moves to each position of opening and closing the valve. The contact pressure of the elastic secondary seal with respect to the gate is kept within an appropriate range regardless of slight fluctuations in the fluid pressure, and the elastic seal member is prevented from being damaged by the fluid pressure or mechanical force. Next, in this type of valve, when the gate moves to the valve closed position, the seal support ring is pulled toward the gate by the cam, and the elastic secondary sealing member is strongly pressed against the gate to enhance the sealing effect. However, in the past, since the gate was activated to open the valve in this high pressure state, the elastic secondary seal was often worn especially at this time. In the present invention, as a second configuration of the actuating device, conventionally, a cam directly provided on the side surface of the gate is formed in a cam wedge slidably mounted in engagement grooves on both sides of the gate, and The cam wedge of is connected to the orthogonal member formed at the end of the valve stem without play in the axial direction of the stem, and the gate is connected to this orthogonal member through the slot having the axial gap. When the gate is pulled by the stem through the actuator and moved from the closed position to the open position, the cam wedge moves in front of the gate and is guided by the cam to loosen the seal support ring away from the gate. As a result, the contact pressure of the elastic secondary seal on the gate is alleviated, and depending on the shape of the cam, the contact pressure of the secondary seal can be released as the gate moves. With the addition of this new actuating device, the gate valve of the present invention sufficiently prevents the secondary seal from being worn.

In the present invention, the primary seal member is 2
It is a composite member type, which makes it easy to replace only the gate side member, which is susceptible to wear, on site, and mainly when the fluid pressure is relatively low, the conventional cooperative cam device (seal support ring and cam on the gate) is used. Providing an omission and simple construction of the sealing device provides many advantages to the industry.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a gate valve according to the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a vertical cross-sectional view of a gate valve having a cam wedge.

FIG. 4 is a sectional view taken along line IV-IV of FIG. 3;

FIG. 5 is a plan view of a cam wedge.

FIG. 6 is a front view of a cam wedge.

FIG. 7 is a cross-sectional view similar to FIG. 3 when using another cam wedge.

FIG. 8A is an explanatory diagram showing an example in which the primary seal body is formed of two members.

8B is a partially enlarged view of FIG. 8A.

9A is a vertical cross-sectional view of another gate valve in which the structure of FIG. 8A is combined with FIG.

9B is a vertical cross-sectional view of a gate valve obtained by combining the structure of FIG. 8A with FIG.

FIG. 9C is a vertical cross-sectional view of the gate valve in which the cooperating cam device is omitted from FIG. 1.

FIG. 9D is a partially enlarged view of a simpler seal member.

9E is a perspective view of the seal member of FIG. 9D.

FIG. 10 is a cross-sectional view of a non-projecting seal ring.

FIG. 11 is a vertical cross-sectional view of a gate valve in which a connecting portion between a gate and a stem is modified.

[Explanation of symbols]

 10 gate valve 11 valve body 12 valve chamber 14 stem 15 gate 15a flow port 27 step groove 28, 148 valve seat 30, 130 tubular portion 31 seal support ring 32, 33 extension portion 34 pin 35 cam edge 35a lower vertical portion 35b inclined portion 35c Upper vertical part 36 Secondary seal holder 36a Secondary seal member 38 Space ring 39 Elastic seal ring 40 Spring member 50 Protrusion prevention member 60 Cam wedge 116 Orthogonal member 125 Gap 126 Engagement groove 128 Seat body 131 Seat surface member 133 Elastic Seal ring 154 Stop nut 156 Bonnet

[Procedure amendment]

[Submission date] April 25, 1991

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] Full text

[Correction method] Change

[Correction content]

[Document name] Statement

[Title of Invention] Gate valve

[Claims]

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION This invention relates to a gate valve,
More specifically, the present invention relates to a gate valve provided with an actuator that relieves and releases the contact pressure of a secondary seal.

[0002]

Gate valves have been in common use for many years, for example in the petroleum industry for oil and / or
It is also used in various equipment such as gas equipment. However, such conventional gate valves are designed for installations with pressures of only a few thousand psi and today, due to exhaustion of energy sources, 30,000
It has become necessary to search for and produce oil and gas under very high pressures in the 0 psi (2,110 kg / cm ² ) or higher range. The use of such high pressure has made it necessary to further enhance the sealing performance and safety of the valve.

A conventional gate valve is usually composed of a valve body having an inlet passage, an outlet passage, and a valve chamber therebetween, and a gate. The gate having the through hole is provided between the valve seats on both sides mounted in the valve chamber and is mounted on the valve stem. The valve chamber is closed by a bonnet fixed to the valve body. The valve stem is attached to a reciprocating device for moving the gate between a closed position where the flow through the flow passage is blocked and an open position where the flow through the flow passage is opened, and reciprocates in the bonnet. Such valves are available from United States Nos. 3,538,938 and 3,696,83.
No. 1 is shown.

Next, as a sealing element in the valve, there are shown an O-ring as shown in US Pat. Nos. 2,957,492 and 3,348,567 and US Pat. No. 4,264,054. It is also known to seal between the valve seat and the valve body using such a non-extrusion seal. It is also known to provide a zero ring seal at the end of the valve seat that contacts the gate, as shown in U.S. Pat. No. 3,696,831. United States Patent No. 3,057,6
Seal ring according to the combination of the port re tetrafluoride ethylene polymers or "Nylon" other low friction plastic rings, known in the No. 30 and No. 3,758,072 as high elastic 0-ring and e.g. trade name "Teflon" Formation is taught. Further, U.S. Pat. No. 3,103,366 uses a ring made of a metal such as thin aluminum having a deformable plastic made of polytetrafluoroethylene in the metal sacrificial ring and a slight change in groove clearance. Teaches a construction which is self-contained and which prevents the plastic ring from protruding through the gap when pressurized.

Further, in order to withstand the high pressure of fluid, there is a type in which a primary seal made of metal and a secondary seal made of an elastic material are used together for the gate. That is, the metal sheet surrounding the flow path in the valve forms a metal-to-metal primary seal for the gate, and when the gate moves to the closed position, the elastic seal moves to the gate side to form a secondary seal for the gate. The composite seal structure designed to
United States of America 4,377,2 by the same inventor as the present application
No. 73. The secondary sealing element shown in this prior art is one elastic ring in which a portion on the gate side is narrowed from its inner and outer peripheral surfaces by a hard ring, and this elastic secondary sealing element is provided in a cam groove on the side surface of the gate. A seal support ring with a guided pin will pull towards the gate as it moves from the open to the closed position and release the secondary sealing element from the gate as the gate moves from the closed to the open position. And the structure. However, with only the structure shown here, the contact pressure of the secondary seal against the gate changes drastically depending on the open and closed positions of the gate, which damages the elastic secondary sealing element and, conversely, the secondary seal does not work at all. was there. In addition, the pressure of the fluid
If relatively low, the primary seal must be metal-to-metal
It is not necessary to limit to a seal .

[0006]

As discussed in US Pat. No. 4,377,273,
One of the problems often encountered with gate valves is that they may not properly form a seal between the gate and the valve seat. This improper sealing often causes gate valves to leak from the seal. In U.S. Pat. No. 4,377,273 by the same inventor of the present application, a double-sided two-way cam is used as a suitable seal for a gate valve to positively strengthen the contact of the seal member with the gate. Disclosed is a structure of a secondary seal made of an elastic material which is intended to be reduced or reduced. Thus, while the configuration disclosed in U.S. Pat. No. 4,377,273 appears to provide advantages in many applications, there may be additional improvements in primary and secondary seal configurations. Have been found. Especially under high pressure conditions, such as when there is a large pressure difference between the two sides of the gate during the formation of the secondary seal, or in the case of a secondary seal located downstream of the gate, the secondary seal often has considerable force. When the gate is pressed against the gate, the gate is moved in the opening direction, so that dragging occurs on the elastic secondary seal surface, and the abrasion of the elastic secondary seal significantly progresses. It also increases the force required to open the valve due to the additional frictional drag on the gate. Such is the case prior to move substantially linearly gates across the sealing surface, rather then desirable that it is possible to appropriately cancel the secondary seal, combined
Reduces sliding resistance of the primary seal member to the gate
It is necessary to consider that .

That is, the secondary seal member does not have to be completely pulled down from the gate, and when the gate moves to open and close the valve, the contact pressure of the seal against the gate is moderately reduced, and the seal is substantially "inoperative". It is desirable that the "pressurized fluid" through the valve in the "state" flow rather somewhat between the seal and the gate to prevent wear.

Further, under the high pressure condition such as when the secondary seal is fully operating with almost no pressure inside the valve body, and then the pressure is applied from the upstream side, the fluid has such a function. It cannot enter the valve chamber in the main body unless it leaks from the secondary seal on the upstream side of the gate. Since the upstream secondary seal is mechanically activated, the operational state of the seal is maintained unless the pressure load of the fluid exceeds the mechanical force. However, in some cases, the fluid pressure suddenly exceeds the mechanical force of the seal and becomes so large that it is ejected from the seal portion, and the elastic ring of the seal device may be broken.

Therefore, under the conditions as described above, a mechanism (for example, spring means) for gradually reducing and releasing the contact pressure from the secondary seal that receives the action of the pressurized fluid is provided so that when the fluid pressure reaches a predetermined value, It is desirable that the pressure rather pull the seal away from the gate to allow fluid to flow through the seal, eg to the valve chamber side, without damaging the resilient seal member. Next, in the primary seal provided on the flow path side in order to buffer the high fluid pressure directly acting on the secondary seal containing the elastic material from the flow path, the conventional valve seat has one tubular member made of metal. Since it is formed as, and the part far from the gate is press-fitted to the valve body, it is difficult to replace it, especially on site. A special tool is required to remove such a fitting sheet,
The fitting hole of the valve body and the fitting surface of the primary seat are damaged by prying between the two when they are removed. Therefore, it is desired to provide a primary valve seat in which only the gate side portion, which is easily worn, can be replaced without damaging the fitting surface between the primary seat and the main body.

[0010]

A gate valve of the present invention basically moves a valve body, a gate, a valve sheet for primary sealing, a secondary sealing device, and a secondary sealing device with respect to the gate. And a cooperating cam device for allowing the valve body to have a valve chamber closed inside by a bonnet and a pair of flow passages arranged in a straight line on both sides of the valve chamber. Is formed with a groove open to the valve chamber side around each inner end of the valve chamber, and the gate has a flow port for communicating the pair of flow channels and a non-hole portion for closing the flow channels. The valve seat is reciprocally movable between the gate positions where one end of the valve seat is connected to the valve stem and the valve opens and closes along a path that crosses the flow passage, and the valve seat is an inner end of the flow passage. Shape around An end surface of the tubular seat portion at the gate at each of the gate positions where the valve is opened and closed, having a portion fitted to a portion farther from the gate of each of the recessed grooves and a tubular seat portion located on the gate side of the portion. To form a primary seal, the secondary seal device having a secondary seal assembly slidably mounted on the circumferential surface of the tubular seat portion of the valve seat, and a cooperating cam device formed on the side surface of the gate. And a seal support ring that partially engages the cam and moves the secondary seal assembly toward the gate when the valve is closed, which solves the conventional problems. Therefore, an operating device capable of relieving and further releasing the contact pressure of the secondary seal with the secondary seal assembly against the gate is provided for the gate. In the present invention
At least the contact surface between the next sealing valve seat and the gate
One is made of a non-metal member .

Further, the secondary seal assembly includes a ring-shaped seal holder slidably disposed in the open groove of the seal support ring surrounding the tubular portion of the valve seat, with respect to the tubular portion. An elastic seal ring held in contact with the tubular portion in the inner groove and a space ring adjacent to the seal ring are provided, and the seal holder is elastic in an annular groove formed on the end surface adjacent to the gate. The secondary sealing member is arranged so as to be able to contact the gate.

Here, the gate valve of the present invention firstly has a spring member having a predetermined spring constant as an urging member as an operating device characterizing the gate valve. The spring member is disposed between the seal support ring and the space ring and biases the elastic secondary seal member as the seal support ring moves relative to the gate by the cooperating cam device, and in some cases Reduces the contact pressure with the gate. Therefore, the strength of this spring member, that is, the spring constant, is such that the spring member appropriately expands and contracts against the pressure under the fluid pressure of a predetermined range flowing through the gate valve, so that the elastic secondary seal member and the gate are It is selected so that the contact pressure generated between them can be relaxed.

The gate valve then modifies the cooperating cam system as the second element of the actuating device. The cooperating cam device has a pin projecting from the inner surface of the extending portion of the seal support ring along the side surface of the gate and a cam edge provided on the side surface of the gate so as to engage with the pin. It is formed on each cam wedge slidably mounted in the engagement groove provided along both sides, and these cam wedges are formed on the orthogonal member formed at the end of the valve stem at least in the axial direction of the stem. The gates are connected without play, and the gate is connected to the orthogonal member via a slot having a slight gap in the axial direction. When the gate is pulled by the stem and moved from the closed position to the open position through the actuator of this configuration, the cam wedge moves by the above-mentioned clearance prior to the gate, and first, the pin of the seal support ring is moved from the cam edge. It is released, and the contact pressure of the secondary seal on the gate is subsequently released.

Further, in the gate valve of the present invention, the valve seat can be constructed as a two-part composite type of a part fitted to the valve body and a part forming a primary seal in contact with the gate. It is possible to replace only the primary seal forming part that is apt to wear.

Finally, the gate valve of the present invention includes a simplified sealing device for application when the fluid pressure is not so high. This type has a spring member as an actuator that relieves the contact pressure of the gate of the secondary seal, but does not have a cooperating cam device. Each gate situ Rubushito is to have a portion and it than extending to the gate-side tubular portion which is fitted to a portion of stage an annular groove formed in the flow path end of the valve body to open and close the valve The end face of the tubular portion is brought into contact with the gate at the position to form a primary seal, at least one of which is a non-metallic member . Usually, an elastic material is often used for the contact surface of the valve seat with the gate. The secondary sealing device includes a secondary seal assembly axially slidably mounted about the tubular portion of the valve seat, the secondary seal assembly axially extending on an outer peripheral surface of the tubular portion of the valve seat. An annular secondary seal holder that is slidably fitted, an elastic secondary seal member that is press-fitted in an annular groove formed on the gate side end surface of the holder, and a secondary seal holder (140) An annular spring member, which is mounted in an annular groove formed in the inner peripheral surface of the valve seat and contacts the tubular portion, has an annular spring member for pressing the secondary seal assembly toward the gate. It is characterized in that it is arranged between the end face of the next seal holder and the side opposite to the gate. In this case, it is also possible that the secondary seal holder has a pair of gate guides extending along the side surface of the gate on the end face on the gate side.

[0016]

The features of the gate valve improved by the present invention to solve the problems of the prior art are as described above. This gate valve has a double-sided parallel type gate connected to the inner end of the valve stem. The handle is operated to move the valve within the valve body between a closed position and an open position. At this time, the primary valve seats disposed in the annular step grooves formed around the inner ends of the flow passages on both sides of the valve body have their inner end surfaces in contact with the valve surface of the gate at least.
A primary seal is always formed, one of which is non-metallic . The contact surfaces of the primary valve seat and the gate are opposed to each other based on a general mechanical fitting tolerance, but they slide against each other when the gate opens and closes. There is. In the present invention, the valve seat is often improved to a two-part type so that the half part near the worn part can be replaced locally.

Next, the seal holder in the secondary seal device that slides on the outer peripheral surface of the primary valve seat has an elastic seal ring between itself and the valve seat surface, and also has an annular secondary seal member on the end face on the gate side. . In the secondary sealing member is an elastic member, the fluid in the flow path which is substantially sealed by conventional metal to primary seal of non-metal, even more completely sealed by adhesion between the gate due to the elastic member, via the valve chamber Prevents fluid leakage from upstream to downstream. However, the elastic secondary seal member that forms a secondary seal with the gate is more susceptible to damage than a metal or a wear-resistant non-metallic material due to sliding friction with the gate surface due to opening and closing of the valve. Therefore, in the present invention, the gate side surface is directly or
With seal support ring moves by being driven by the cam provided on the contact with the flow path direction of the seal holding member and movable mainly gate is sufficiently elastic secondary seal member having a seal holding member when closing the valve so as to pressure contact with the gate
It is

In the present invention, in order to reduce the extreme pressure contact between the elastic secondary seal member and the gate, a new spring member is provided between the seal support ring and the secondary seal holder to provide a secondary seal. The contact pressure is not so strong that the elastic seal material is damaged, and the sealing property is appropriately maintained even when the pressure contact is released. Also at the time of transferring the gate to the open position
In order to eliminate a delay in pressure contact releasing, when the cam wedges of the separate the sides of the gate relative movement capable mounted, the cam provided on the wedge, for moving the gate from the valve closed position to the open position, the valve stem The engagement structure between the three members was improved so that the cam wedge was slightly moved prior to the movement of the gate. Therefore, the seal support ring moves away from the gate in accordance with the preceding movement of the cam wedge, and the elastic secondary seal member also tries to separate from the gate. However, in the present invention, due to the presence of the spring member, the secondary seal member is not completely separated from the gate, and is retracted while maintaining the sealing property under a proper contact pressure, during which the gate is elastically moved from the closed position to the open position. It is moved without damaging the secondary seal member.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The gate valve of the present invention is provided with a secondary seal assembly mainly in contact with an elastic material, in addition to a primary seal mainly in contact with the gate by a rigid material. This gate valve is described in the above-mentioned US Pat. No. 4,377,273.
Like the gate valve disclosed in the above publication, it is of a stem lifting type. The prior application of the same inventor, U.S. Pat. No. 4,377,273 (hereinafter also simply referred to as the same application of the same person), will be occasionally compared and referred to in the following description. It is a further improvement of the technical inadequacies.

Referring to FIGS. 1, 8A and 9A. The gate valve 10 has a valve body 11, and a valve chamber 12 is formed inside the valve body 11.
A bonnet (not shown) is attached to the upper portion of the gate valve 10, and the bonnet closes the upper end of the valve chamber 12 and seals between the valve body 11 and the stem 14.

The gate valve 10 has a gate 15 arranged in the valve chamber 12. In general, the gate 15 has a rectangular cross section, its two surfaces contacting the valve seats 28 and 131 are parallel to each other, and the upper portion thereof is connected to the stem 14. Therefore, the vertical movement of the stem 14 moves the gate 15 up and down. In this example, the stem 1
A stud 16 with a screw is formed at the lower end of 4. On the other hand, a screw hole 17 having a female screw is formed in a cylinder 18 that is fitted into a cylindrical hole 19 that laterally penetrates the upper portion of the gate 15, and the stud 1 is inserted into this hole 17.
6 is screwed. The stud 16 is the cylindrical portion 2 of the stem 14.
It is connected to 1. In addition, the cylindrical portion 21 is the gate 1
5 is inserted into the opening 20 on the upper surface. Further, a truncated cone portion 22 is formed on the stem 14 above the cylindrical portion 21. The truncated cone portion 22 acts as a stopper and contacts the lower surface of the bonnet (not shown) to limit the rise of the stem 14.

The vertical movement of the stem 14 can be accomplished by various methods. In this example, the stem 1
Reference numeral 4 is screwed into a yoke nut (not shown), and the rotation of the yoke nut moves the stem 14 in its longitudinal direction, and the gate 15 moves up and down in accordance with the movement. There are various other methods of connecting the stem 14 and the gate 15, and an improved example will be described later with reference to, for example, FIG.

As shown in the figure, the valve body 11 is formed with projecting portions 23 and 24 which project toward the valve chamber 12 so as to face each other. The protrusions 23 and 24 are formed in the valve body 1
1 inside the flow paths 25 and 26 (valve chamber 12
The side) is formed so as to surround the end. On the other hand, a flow port 15a is formed in the gate 15 so as to penetrate therethrough. The flow port 15a is set so as to be aligned with the flow paths 25 and 26 and to open the valve when the gate 15 rises.

An annular step groove 27 is concentrically formed on the protrusions 23 and 24 so as to face the flow paths 25 and 26. In the embodiment shown in FIGS. 1 and 3, a valve seat 28 for primary sealing is attached to this step groove 27. The valve seat 28 has a large-diameter portion 29 that is integral with and is fitted to the valve body 11. The end face of the tubular portion extending from the valve seat 28 is in contact with the valve face of the gate 15 and normally flows into the fluid. At least
One forms the non-metal primary seal. Of the primary seal
The end faces prevent the fluid in the flow paths 25 and 26 from leaking into the valve chamber 12 and guide the vertical movement of the gate 15.

In the embodiment of FIGS. 8A, 9A and 9B, the valve seat body 128, which is slightly shorter than the integral type, is attached to the step groove 27. The valve seat body 128 has a ring-shaped seat surface member 131 screwed into the tubular portion 129 having a slightly smaller diameter. The inner flange surface of the gate side seat surface member 131 is engaged with the outer end surface 132 of the tubular portion 129 of the valve seat body 128.
A sufficient sealing interface is formed between the two. The tubular portion 1
The elastic seal member 133 is mounted in the annular space 138 formed between the sheet surface member 131 and the seat surface member 131, and the tubular portion 12
9 and the seat surface member 131 can be more reliably sealed. The annular space 138 is formed by the truncated cone surface 139 at the outer peripheral corner of the tubular portion 129. The end surface 134 of the seat surface member 131 engages with the gate 15 and is at least between the two.
Also forms a primary seal, one of which is non-metallic .

The seat surface member 135 shown in FIG. 8B can be used in place of the seat surface member 131 shown in FIG. 8A. An annular groove 136 is formed on the end surface of the seat surface member 135. Then, rubber, elastic sealing ring 137 made of an elastic material such as Teflon is mounted, through the bullet <br/> seal ring 137 between the seat surface member 135 and the gate 15 well within the groove 136 A transparent seal is formed. Using this method, the processing accuracy of the more required in the case of metal-to-metal seal against gate is unnecessary, in addition, if the low pressure used can be suppressed cost quite low. 8A and 8B show, for reference, a simple configuration in which the secondary seal assembly is omitted. Of course, the structure of the primary seal with the elastic seal ring 137 shown in FIG. 8B can be adopted in the configurations of FIGS. 9A and 9B described later.

Incidentally, instead of the primary valve seat 28 made of one member as shown in FIGS. 1 and 3, FIG. 8A,
As shown in FIG. 9A and the like, the valve seat main body 128 fitted to the valve main body 11 is screwed to the seat surface member 131.
When the seat surface member 1 is detachably used, even if the end surface 134 that makes seal contact with the gate 15 is worn, the seat surface member 1
Since only 31 can be easily replaced by removing it from the threaded portion with the valve seat body 128 , the seat surface member 13
1 can be made of wear resistant non-metallic material or elastic material
I can .

Next, the secondary seal will be described. Figure 1,
As shown in FIG. 9A, the secondary seal, which is supplemented to the primary seal, has a seal support ring 31 for strengthening its contact pressure when the valve is closed, around the tubular portion 30 of the valve seat 28 of the primary seal (FIG. 1). Or the valve seat body 1
It is arranged around the 28 sheet surface members 131 (FIG. 9A). The seal support ring 31 is formed in the shape of a flanged ring and has an inward opening groove 37 at the end portion on the gate 15 side, so that its shape is L-shaped in cross section. Further, the seal support ring 31 has a pair of axially extending portions 32 and 33 on its side portions, and these extending portions 32 and 33 extend along both side surfaces of the gate 15, respectively. (Fig. 2
reference). Each extension 32, 33 has a short cylindrical pin 34. This pin 34 is the gate 1 of each extension 32, 33.
It is fixed to the inner flat surface along 5. On the other hand, the gate 15 has cam edges 35 on both sides thereof. Each cam edge 35 comprises a vertical portion 35a located at the lower end of the gate and an inclined portion 35b located above it. Pin 34
Is driven by engagement with the cam edge 35 to move the seal support ring 31 toward the gate 15. When the gate 15 is lowered to the closed position shown by the lowering of the stem 14, the pin 34 moves along the cam edge 35 from its position engaged with its vertical portion 35a to the position engaged with the inclined portion 35b, Both seal support rings 3
1 is drawn to the gate side. In the prior application U.S. Pat. No. 4,377,273 by the same inventor as the present application, a double-sided type having a front edge and a back edge for separating and contacting a secondary seal with respect to a gate with respect to the single-sided cam edge of the present application is disclosed. Was provided with a groove. This modification is related to the fact that the present invention newly provides an actuator capable of relieving the contact pressure of the secondary seal and further releasing it.

Further, referring to FIGS. 1 and 9A, the secondary seal assembly is mounted in the open groove 37 of the seal support ring 31. This secondary seal assembly includes a seal support ring 31 and a primary valve seat 28.
Alternatively, a metal seal holder 36 slidably supported between the seat surface member 131 is provided. The structure of this secondary seal assembly is different from the simple seal element in the previous application of the same person in which the elastic ring is sandwiched by the hard ring from the inner and outer circumferences, and the contact pressure of the secondary seal can be relaxed when the gate is opened and closed. Is.

The seal holder 36 is a stepped annular ring having an inner groove and is L-shaped in cross section. Further, the seal holder 36 has an annular elastic secondary seal member 36a attached to the annular groove on the end face on the gate side by press fitting or the like. In addition, the inner groove of the seal holder 36 is shown in FIGS.
As shown in B, the space ring 38 having a rectangular cross section and the elastic seal ring 3 which can be compressed are slidably arranged.
9 is equipped. Since this elastic seal ring 39 is compressively deformable, when it is compressed through the space ring 38, the seal ring 39 comes into close contact with the surrounding wall surface to form a sufficient internal seal. As the elastic seal ring 39,
For example, an O-ring having a circular cross section formed of a compressible elastic material can be used. In the embodiment shown in FIG. 10, the elastic seal ring 39 is a compressible elastic ring whose cross section is close to a rectangle, and includes a protrusion preventing member 50 at the corner portion.

In a more preferred embodiment, a pressure relief device for the seal holder 36 is provided. In the embodiment of FIGS. 1 and 9A, the pressure relief device includes a spring member 40 disposed between the seal support ring 31 and the space ring 38. Since a spring constant having a spring constant selected in consideration of fluid pressure is used as the spring member 40, when the seal holder 36 is pressed against the gate 15 to form a secondary seal, a proper contact pressure is constantly applied. Is maintained between the gate and. But upstream (Fig. 1,
When a predetermined or more pressure is applied to the seal holder 36 (more specifically, the elastic seal ring 39) by the fluid pressure in the flow path 26 side in FIG. 9A, the spring member 40 is compressed. When the spring member 40 is largely compressed, the seal holder 36 separates from the gate 15 and the elastic seal member 3
Prevent the destruction of 6a.

The spring constant of the spring member 40 is determined by the seal holder 36, the elastic seal ring 39, and the secondary seal member 36.
It is determined based on the constituent materials of a and their pressure resistance to the critical pressure. The choice of this spring constant is a design issue that can be determined by one of ordinary skill in the art based on the disclosure of the present invention.

The spring member 40 may be formed of a plurality of springs, and its spring constant may be arbitrarily changed according to the operating condition of the secondary seal. In the illustrated embodiment, the spring member 40 is a flat spring having a spring constant that can respond to a predetermined level of pressure. It should be noted that this may be a highly compressible ring seal.

Therefore, in the embodiment shown in FIGS. 1 and 9A, the presence of the spring member 40 serves as a buffer function for the upstream fluid pressure, and when the pressure is abnormally high, the seal holder 36 is quickly removed from the gate. It also has a release function to pull it apart.

Further, in the gate valve of the present invention, the above-described cam edge 3 directly engraved on both side surfaces of the gate 15 is provided.
Instead of 5, a cooperating cam device of the type using a separate cam wedge can be used. This cooperating cam device is shown in FIG.
Engagement groove 1 in the vertical direction near both sides of the gate as shown in
26 has cam wedges 60 which is slidably fitted me along. This cam wedge is set so that when the valve opens, it slightly moves up before the gate moves up. Therefore, the restriction of the cam edge with respect to the pin 34 of the seal support ring 31 is loosened, and then the secondary seal is loosened. The gate will move upward in the figure. 3 and 9B show a gate valve provided with the cam wedge 60. The terms "vertical" and "horizontal" used in the description of these figures refer to the valve illustrated in FIG. 3 or 9B. In the figures, the valve is shown upright with the stem 14 extending upwardly from its top. As shown in FIGS. 5 and 6, the cam wedge 60 is formed in a rectangular shape, and a notch 62 is formed in the lower portion thereof. Due to the notch 62, the one-sided cam edge 3
5 are formed symmetrically. The cam edge 35 has substantially the same shape and function as the cam edge 35 provided directly on both side surfaces of the gate 15 as shown in FIGS. 1 and 9A. The cam edge 35 is the lower vertical portion 35.
a and an upper inclined portion 35b. As described in the section of FIG. 1 and FIG. 9A, since the cam edge 35 is cam-engaged with the pin 34, when the gate 15 is lowered to the closed position by the lowering of the stem 14, the pin 34 is gently moved to the cam edge 35. From the vertical portion 35a to the inclined portion 35b
Move to. As a result, each seal support ring 31 integrated with the pin 34 is moved to the gate 15 side, and the contact pressure of the secondary seal is strengthened.

The cam wedge 60 has tabs 64 at both ends thereof . Each of these tabs 64 extends outwards and the gate 1
5 is slidably engaged with an engagement groove 126 formed in the groove 5.
As a result, the cam wedge 60 is supported by the gate 15 and is relatively movable in the vertical direction (see FIGS. 3, 9B and 4). A horizontal slot 68 having a rectangular cross section is formed in the upper portion of the cam wedge 60. As will be described in more detail below, this slot 68 defines the orthogonal member 1 at the lower end of the stem 14.
It is formed so that 16 can be fitted.

As shown in FIGS. 3 and 9B, an extension portion 121 having a rectangular horizontal cross section is formed in the lower portion of the stem 14, and a rectangular parallelepiped orthogonal member 11 is formed at the lower end of the extension portion 121.
Since 6 is fixed, both form an inverted T-shaped block. Further, in this embodiment, the width of the orthogonal member 116 in the left-right horizontal direction is as shown in FIG.
It is set to be wider than the horizontal width of 21 and narrower than the horizontal width of the gate 15. In the direction perpendicular to the plane of the drawing, the horizontal length of the orthogonal member 116 is set to be longer than the horizontal length of the extension portion 121 and substantially equal to the horizontal length of the gate 15. Each lengthwise end of the orthogonal member 116 is formed for slidable engagement within a slot 68 (FIG. 6) of the cam wedge 60, but between these ends and the slot 68. Vertical play is minimal.

The gate 15 has vertical (up and down) slots 120 and horizontal (horizontal) slots 117 (see FIGS. 3 and 9).
(See B) and are formed. The extending portion 121 of the stem 14 and the orthogonal member 116 are engaged in the slots 120 and 117, respectively. In this case, the slot 120 is formed so as to slidably hold the extending portion 121 and minimize the lateral (left and right in the drawing) play of the gate 15 with respect to the stem 14. However, the dimension of the slot 117 provided in the gate 15 in the vertical (vertical) direction is set larger than the dimension of the orthogonal member 116 at the lower end of the stem in the vertical (vertical) direction.
The stem 14 can be vertically moved by a predetermined dimension (125 in the figure) corresponding to the difference without the gate 15 being vertically moved, and the cam wedges 60 on both sides of the gate are driven by the stem 14 at this time.

In this embodiment, the stem 14
To combine the gate 15 with the cam wedge 60,
It is necessary to set the length of the extending portion 121 of the stem 14 in the horizontal direction (right angle to the paper surface) to be shorter than that of the slot 120 of the gate 15 in the same horizontal direction, and to form a space between them.
The reason is that the stem 14 is moved to one side of the gate 15 and the wedge 60 is attached to the other side of the gate. This void is shown as a blank area in FIG. Such dimensional difference is not necessary for the horizontal (left and right in the drawing) width of the extending portion 121 of the stem. Further, the stem, gate and cam wedge can be combined with each other in a form different from the above.

When the cam wedge 60 constructed as described above is used, the gate valve 10 is closed (see FIGS. 3 and 9).
In the case of B), the seal support ring 31 is already drawn to the gate 15 by the lowering of the cam wedge 60, and the cam edge guides the pin 34, so that the secondary seal operates. When the gate valve 10 is opened, while the stem 14 is raised by a certain distance (125 in the drawing), the gate 15 is not raised and only the cam wedge 60 is pulled up as described above. This advance movement of the cam wedge 60 causes the edge 35 of the cam wedge 60 to slightly release the pin 34 along its upper ramp 35b (FIG. 6) before the gate 15 begins to rise, thereby contacting the secondary seal. The pressure is released, and abrasion of the elastic secondary seal member 36a due to sliding on the gate surface is effectively prevented.

When the gate is lowered by the stem 14 to close the valve, the frictional resistance of the primary seal members 28 and 131 against the gate 15 causes
The gate 15 tries to stop at the high position shown in FIGS. 3 and 9B. In addition, if a stopper (not shown) is provided below the gate 15 and the lowering of the gate 15 is restricted by this stopper, the preceding operation of the cam wedge 60 is surely performed when the stem 14 is raised. It is possible to prevent wear of the secondary seal member 36a.

In FIG. 6, the cam edge 35 whose upper portion is different from the cam edge 35 shown in FIGS. 1, 3, 9A and 9B is shown by a broken line. That is, the cam edge 35 shows an upper vertical portion 35c (broken line portion) which is directed upward in the middle of the conventional inclined portion 35b. Since the upper vertical portion 35c is formed in parallel with the valve surface of the gate 15, the pin 34 is attached to the upper vertical portion 3c.
Seal support ring 3 by engaging with 5c
The movement of 1 toward the gate 15 is smaller than that of the cam edge before modification, and therefore the secondary seal is not tightened more than a certain amount.

FIG. 7 shows a cam wedge in which the width of the cam wedge 60 shown in FIGS. 4 to 6 is changed. The cam wedge 60 positions the gate 15 at the center thereof so that the opposing secondary seals on both sides of the gate act uniformly. The horizontal cross-sectional shape of the cam wedge 60 in the case of FIG. 7 is basically the same as the horizontal cross-sectional shape of the cam wedge 60 of FIG. 4, but differs in the following points. That is, when the cam wedge 60 is mounted on the gate 15, a gap is formed between the tab 64 and the engagement groove 126, and thus between the cam wedge 60 and the gate 15, and the cam wedge 60 is indicated by an arrow with respect to the gate 15. It is a point that can move a little in the direction of 66.

Therefore, when the cam wedge 60 having a gap for moving in the lateral direction is attached to the gate 15 (see FIG. 7), the floating of the cam wedge 60 causes the gate 15 to oppose the secondary seal. The misalignment between the gaps is naturally compensated, and uniform secondary seals are formed on both surfaces of the gate 15.

Thus, in the embodiment shown in FIGS. 3 and 9B, the seal actuation mechanism associated with the cam wedge 60 relieves the contact pressure of the secondary seal prior to moving the gate from the closed position to the open position. Since it is possible to compensate for the misalignment between the gate and the seals on both sides, it is not necessary to forcibly provide the buffer spring member between the seal support ring 31 and the secondary seal holder 36. .

In the embodiment of FIG. 11, FIG. 3 and FIG. 9B
Unlike, the orthogonal member 116 at the lower end of the stem is engaged in the slot 117 'of the gate 15 without a gap, and the same spring member 40 as in the case of FIGS. 1 and 9A is used. Since there is no gap, the vertical width of the slot 117 'and the thickness of the orthogonal member 116 are substantially the same. Also in this embodiment, the composite type primary sheets 128 and 131 can be used as in the case of FIGS. 9A and 9B.

In the embodiment shown in FIG. 11, the movement of the seal support ring 31 toward the gate 15 side is restricted so that the spring member 40 is not compressed beyond its elastic limit. The movement of the seal support ring 31 is limited by the axial length of the seal support ring 31 being longer than that in FIGS. 9A and 9B, and thus the inner end surface 153 of the seal support ring 31 contacts the gate 15. Also, in order to prevent the seal support ring 31 from abrading the surface of the gate 15, after the inner end surface 153 of the seal support ring 31 comes into contact with the gate 15, the stem 15 is prevented from further descending.
The descent has been adjusted. That is, the descent of gate 15 is limited by properly stopping the descent of stem 14. And this stop of the stem 14 is stopped by the stem 14
This is accomplished by mounting a stop nut 154 on the outer side of the and then threading it onto a stem nut 155 that regulates the position of the handle 157 with respect to the bonnet 156 so that the handle is properly secured. To adjust the screwing stop position of the stop nut 154 with respect to the stem nut 155, the seal support ring 31 is moved by the cam edge 35 of the cam wedge 60 via the pin 34 to the gate 15 of the seal support ring 31.
The inner end surface 153 and the surface of the gate 15 are brought into contact with each other and must be aligned. Stem 1
By limiting the descent of 4 the cam wedge 6
0, the seal support ring 31, the gate 15 and the stem 14 are also prevented from being overloaded.

Next, an embodiment using a simple seal assembly without a seal support ring will be described with reference to FIGS. 9C, 9D and 9E.

In FIG. 9C, a ring-shaped secondary seal holder 140 is axially slidably engaged with the tubular portion 149 of the valve seat 148. An annular elastic secondary seal member 140a is attached to the end surface 142 of the secondary seal holder 140 by press fitting or the like. The secondary seal holder 140 has a 0-ring 140b in the inner groove 150. The O-ring 140b forms a seal with the outer peripheral surface of the tubular portion 149. Figure 9C
In the embodiment of FIG.
44 and the secondary seal holder 140 between the spring member 14
1 is provided. Further, in the embodiment of FIG. 9D, a ring-shaped convex portion 152 is formed on the outer periphery of the valve seat 148, and a pocket 145 for storing the spring member 141 is formed between the valve seat 148 and the secondary seal holder 140. This spring member 14
1, the end surface 142 of the elastic secondary seal member 140a is brought into contact with the gate 15. Further, when a strong pressure is applied to the secondary seal surface by the pressurized fluid from the upstream side, the spring member 141 is compressed and the secondary seal holder 140 is separated from the gate 15, so that the elastic secondary seal member 14
0a is not damaged. However, when the fluid pressure is within the predetermined range, the spring member 141 effectively acts to maintain the secondary seal.

In the embodiment of FIGS. 9C and 9D, the secondary seal holder 140 is provided with gate guides 143 (see FIG. 9E) extending along both side surfaces of the gate 15. These prevent rotation of the secondary seal holder 140 and lateral runout of the gate 15.

Although a spring is generally used as the spring member 141, an elastic 0-ring or the like may be used.

Although the present invention has been described based on several embodiments, the detailed configurations may be combined with each other without departing from the scope of the invention. For example, by applying a cam wedge 60 separate from the gate to an embodiment of the spring member 40 as in FIGS. 1 and 9A, when moving the gate to open the valve, the gate 15 and the secondary seal member are It is also possible to more effectively relieve and release the contact pressure. Furthermore, a spring member may be applied to the embodiment of FIGS. 3 and 9B so that the secondary sealing device 36 is effectively retracted when the pressure of the fluid reaches a predetermined value or more. Further, in the embodiment of FIG. 9C, a two-member composite type valve seat mechanism can be used. In addition,
In the present invention, valve seats and gates are used throughout the embodiments.
Limit the so-called primary seal between the
Without the need to set the valve seat and gate
At least one (or both) has a non-metallic material
We regard things as basic elements. Say here
Non-metallic materials are not necessarily limited to elastic materials,
It is desirable that the material has low friction and low friction.

[0054]

According to the present invention, an annular primary seal member and an elastic secondary seal disposed around the inner end of a fluid passage from both sides of a gate that moves in the valve body for opening and closing the valve. A gate valve of a type that keeps the liquid seal inside the valve by concentrically contacting the member, and provided an operating device on the gate that mainly relieves the contact pressure of the secondary seal and can release it. It is characterized by As a first element of this actuating device, a spring member is provided behind the annular holding body of the elastic secondary seal member so that the secondary seal member is always urged toward the gate. The secondary seal irrespective of the position of the seal support ring which is contacted via this spring member and is relatively moved in the direction toward and away from the gate by the cam formed on the side surface of the gate when the gate moves to each position of opening and closing the valve. Regardless of slight fluctuations in the fluid pressure applied to the end face of the holder, the contact pressure of the elastic secondary seal with respect to the gate falls within an appropriate range, and the elastic secondary seal member is damaged by fluid pressure and mechanical force. Prevent. Then, in this type of valve, when the gate moves to the valve closed position, the seal support ring is pulled toward the gate side by the cam, and the elastic secondary seal member is strongly pressed against the gate to enhance the sealing effect.
However, in the past, since the gate was activated to open the valve in this high pressure state, the elastic secondary seal was often worn especially at this time. In this invention, the secondary seal
As a second configuration of the above-mentioned actuating device, conventionally, a cam directly provided on the side surface of the gate is formed in a cam wedge slidably mounted in engagement grooves on both sides of the gate, and these cams are also provided. The wedge is connected to the orthogonal member formed at the end of the valve stem in the axial direction of the stem without play,
The gate was connected to this orthogonal member through a slot having an axial clearance so that when the gate was pulled by the stem and moved from the closed position to the open position via the actuator of this configuration, the gate preceded the gate. The cam wedge moves, the guide ring guides the seal support ring away from the gate, and the contact pressure of the elastic secondary seal against the gate is alleviated accordingly. Accordingly, the contact pressure of the secondary seal can be released. With the addition of this new actuating device, the gate valve of the present invention sufficiently prevents the secondary seal from being worn.

In the present invention, the primary seal member is 2
It is a composite member type, and it is easy to replace only the gate side member, which is susceptible to wear, on site.
Applied to reduce friction with the gate, and where the fluid pressure is relatively low, the seal has a simple structure without the conventional cooperating cam device (seal support ring and cam on the gate). Providing the device gives the industry many advantages.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a gate valve according to the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a vertical cross-sectional view of a gate valve having a cam wedge.

FIG. 4 is a sectional view taken along line IV-IV of FIG. 3;

FIG. 5 is a plan view of a cam wedge.

FIG. 6 is a front view of a cam wedge.

FIG. 7 is a cross-sectional view similar to FIG. 3 when using another cam wedge.

FIG. 8A is an explanatory diagram showing an example in which the primary seal body is formed of two members.

8B is a partially enlarged view of FIG. 8A.

9A is a vertical cross-sectional view of another gate valve in which the structure of FIG. 8A is combined with FIG.

9B is a vertical cross-sectional view of a gate valve obtained by combining the structure of FIG. 8A with FIG.

FIG. 9C is a vertical cross-sectional view of the gate valve in which the cooperating cam device is omitted from FIG. 1.

FIG. 9D is a partially enlarged view of a simpler seal member.

9E is a perspective view of the seal member of FIG. 9D.

FIG. 10 is a cross-sectional view of a non-projecting seal ring.

FIG. 11 is a vertical cross-sectional view of a gate valve in which a connecting portion between a gate and a stem is modified.

[Explanation of reference numerals] 10 gate valve 11 valve body 12 valve chamber 14 stem 15 gate 15a flow port 27 step groove 28, 148 valve seat 30, 130 tubular portion 31 seal support ring 32, 33 extension part 34 pin 35 cam edge 35a lower part Vertical part 35b Inclined part 35c Upper vertical part 36 Secondary seal holder 36a Secondary seal member 38 Space ring 39 Elastic seal ring 40 Spring member 50 Protrusion prevention member 60 Cam wedge 116 Orthogonal member 125 Gap 126 Engagement groove 128 Seat body 131 Seat surface member 133 Elastic seal ring 154 Stop nut 156 Bonnet ─────────────────────────────────────── ───────────────

[Procedure amendment]

[Submission date] September 20, 1995

[Procedure amendment 4]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a gate valve according to the present invention.

FIG. 2 is a sectional view taken along line II-II in FIG.

FIG. 3 is a vertical cross-sectional view of a gate valve having a cam wedge.

4 is a sectional view taken along line IV-IV in FIG.

FIG. 5 is a plan view of a cam wedge.

FIG. 6 is a front view of a cam wedge.

FIG. 7 is a cross-sectional view similar to FIG. 3 when using another cam wedge.

FIG. 8 is an explanatory diagram showing an example in which the primary seal body is formed of two members.

9 is a partially enlarged view of FIG.

10 is a vertical cross-sectional view of another gate valve in which the structure of FIG. 8 is combined with FIG.

11 is a vertical cross-sectional view of a gate valve in which the structure of FIG. 8 is combined with FIG.

FIG. 12 is a vertical cross-sectional view of the gate valve in which the cooperating cam device is omitted from FIG.

FIG. 13 is a partially enlarged view of a simpler seal member.

14 is a perspective view of the seal member of FIG.

FIG. 15 is a cross-sectional view of a non-projecting seal ring.

FIG. 16 is a vertical cross-sectional view of a gate valve in which a connecting member for connecting a gate and a stem is modified.

[Explanation of reference numerals] 10 gate valve 11 valve body 12 valve chamber 14 stem 15 gate 15a flow port 27 step groove 28,148 valve seat 30,130 tubular portion 31 seal support ring 32,33 extension portion 34 pin 35 cam edge 35a lower part Vertical part 35b Inclined part 35c Upper vertical part 36 Secondary seal holder 36a Secondary seal member 38 Space ring 39 Elastic seal ring 40 Spring member 50 Protrusion prevention member 60 Cam wedge 116 Orthogonal member 125 Gap 126 Engagement groove 128 Seat body 131 Seat surface member 133 Elastic seal ring 154 Stop night 156 Bonnet

[Procedure Amendment 5]

[Document name to be corrected] Drawing

[Correction target item name] All drawings

[Correction method] Change

[Correction content]

FIG.

[Fig. 2]

[Figure 4]

[Figure 5]

[Figure 6]

[Figure 7]

[Figure 9]

[Fig. 13]

FIG. 14

FIG. 15

[Figure 3]

[Figure 8]

[Figure 10]

FIG. 11

[Fig. 12]

FIG. 16

Claims (11)

[Claims] 1. A valve main body, a gate, a valve seat for primary sealing, a secondary sealing device, and a cooperating cam device for moving the secondary sealing device with respect to the gate. Has a valve chamber closed by a bonnet, has a pair of flow passages arranged in a straight line on both sides of the valve chamber, and has a groove open to the valve chamber side around each inner end of these flow passages. The gate is disposed in the valve chamber with a flow port that connects the pair of flow paths and a non-hole portion that closes the flow path, and one end of the gate is connected to the valve stem. The valve seat can be reciprocated between gate positions where the valve opens and closes along a path that crosses the flow path, and the valve seat is fitted to a portion of each groove formed around the inner end of the flow path far from the gate. Part to be worn And a tubular seat portion located on the gate side of the valve seat, and the end face of the tubular seat portion is in contact with the gate at each gate position where the valve opens and closes to form a primary seal. A secondary seal assembly slidably mounted on the circumferential surface of the tubular portion of the gate, the cooperating cam device partially engaging the cam formed on the side of the gate and the secondary seal. A gate valve including a seal support ring that moves the assembly toward the gate when the valve closes, wherein the contact pressure of the secondary seal by the secondary seal assembly against the gate is relaxed and even released. A gate valve characterized in that a possible actuating device is provided for the gate. 2. An open groove (3) in a seal support ring (31) wherein said secondary seal assembly surrounds a tubular portion (30, 130) of said valve seat (28, 128).
7) A ring-shaped seal holder (36) slidably disposed in the tubular portion (30, 130) and an inner groove thereof is held in contact with the tubular portion (30, 130). Elastic seal ring (39) and a space ring (38) adjacent to the seal ring (39),
The seal holder (36) further has an elastic secondary seal member (36a) disposed in an annular groove formed on an end surface of the seal holder (36) adjacent to the gate (15) so as to be able to contact the gate. Gate valve described in paragraph. 3. The actuating device comprises a spring member (40) having a predetermined spring constant as an urging member, the spring member including a seal support ring (31) and a space ring (3).
8), which is disposed between the seal support ring (31) and
3. The structure according to claim 2, which is configured to relieve a contact pressure generated between the elastic secondary sealing member (36a) and the gate when the cooperating cam device moves relative to the gate. Gate valve. 4. The valve seat is a flow path (25, 26).
A seat body (128) in which a portion fitted into a part of each annular groove located around the inner end and a tubular portion (129) having a slightly small diameter are integrated, and a coaxial seat surface detachably attached to the seat body (128) A seat (131), the seat face member having its annular end face (134) in contact with the gate to form a primary seal, and the seal support ring (31) and the secondary on the outer peripheral surface of the seat face member. The gate valve according to claim 2, wherein the seal assembly is slidably disposed. 5. The valve seat includes a seat body (1
28) The seat surface member (131) is detachably connected by screwing, and the plane perpendicular to the axis where the seat body and the seat surface member are in contact with each other is a sealing surface. The described gate valve. 6. The seal support ring (31) in the cooperating cam device has extension portions (32, 33) extending in parallel along both side surfaces of the gate, each extension portion being provided on an inner surface thereof. The pins (34) are provided in a protruding manner, while the cam formed on the side surface of the gate has a single-sided cam edge (35) that engages with each pin (34), and each cam edge (35) is at least By having a lower vertical portion (35a) and a sloped portion (35b) above it, each pin (34) being guided by the sloped portion (35b) as the gate moves downwards towards the closed position. , The seal support rings (31) on the upstream and downstream sides of the gate are moved toward the gate, and between the elastic secondary seal member (36a) closer to the gate than the support ring (31) and both sides of the gate. Secondary sea 4. The gate valve according to claim 3, wherein a ring is formed, and a contact pressure of the secondary seal is relieved by the spring member (40). 7. The cooperating cam device includes an extension portion (32, 32) extending along a gate side surface of a seal support ring (31).
33) The pin (34) protruding from the inner surface and the pin (3
4) a cam edge (35) engageably provided on the side surface of the gate, and the cam edge (35) is slidably attached to an engagement groove (126) provided along both sides of the gate. Formed on each cam wedge (60), these cam wedges (60) include a valve stem (1).
4) is connected to the orthogonal member (116) formed at the end portion of 4) without play at least in the axial direction of the stem, and the gate has a slot (117) having a clearance (125) in the axial direction with the orthogonal member (116). When the gate is pulled by the stem (14) via the actuating device of this configuration and is moved from the closed position toward the open position, the cam wedge (60) is moved by the above-mentioned clearance before the gate. The gate valve according to claim 2, wherein the pin (34) of the seal support ring (31) is released from the cam edge (35) and then the contact pressure of the secondary seal with the gate is released. . 8. A valve main body, a gate, a valve seat for primary sealing, and a secondary sealing device, wherein the valve main body has a pair of flow paths arranged in a straight line on both sides of a valve chamber therein. A step groove opened to the valve chamber side is formed around the inner end of each flow passage, and a gate is provided in the valve chamber and has a flow port that connects the pair of flow passages and is connected to the valve stem. The valve seat has a portion where the valve seat is fitted in a part of the annular groove and a tubular portion which extends toward the gate side from the valve seat. A secondary seal assembly in which an end face of a tubular portion is in contact with a gate at each of the gate positions to be opened and closed to form a primary seal, and a secondary sealing device is axially slidably mounted around the tubular portion of the valve seat. Gate valve having An annular secondary seal holder (140) in which the secondary seal assembly is axially slidably fitted to the outer peripheral surface of the tubular portion (149) of the valve seat (148), and the holder ( 140) an elastic secondary seal member (1) press-fitted into an annular groove formed on the end face on the gate side.
40a) and an annular groove (150) formed in the inner peripheral surface of the secondary seal holder (140), and the tubular portion (14)
9) comprises an elastic ring (140b) and an annular spring member (141) for pressing the secondary seal assembly towards the gate, the shoulder (144) of the valve seat (148) and the secondary seal retention. The gate valve according to claim 1, wherein the gate valve is disposed between the body (140) and the end surface on the side opposite to the gate. 9. (a) A valve chamber is provided inside, and a pair of flow passages are arranged on both sides of the valve chamber in a straight line, and a groove is formed around the inner end of each of these flow passages. A valve body formed, and (b) a non-perforated section and a section having a through-flow passage, which is disposed in the valve chamber, and a valve is opened to allow the through-flow passage to flow through the valve chamber. A gate movable within the valve chamber between a position aligned with the passage and a position where the valve is closed and the non-perforated section is aligned with the flow passage of the valve chamber; and (c) the inner end of the flow passage. The ring-shaped seat is provided in each of the grooves in the periphery and moves between an open position and a closed position with the closing member facing each other, and the ring when the gate is in the closed position. The primary seal is formed on the sheet A valve seat, the valve seat is press-fitted to the valve body, and the seat body is detachably attached to the seat body member and has a contact surface for the gate to form a seal for the gate. And a seat surface member that operates. 10. The gate valve according to claim 9, wherein the primary seal has elasticity. 11. The gate valve according to claim 9, wherein the primary seal is a metal-to-metal seal.