Gate valve with self-closing mechanism

Abstract

To provide a gate valve having a self-closing mechanism that allows easy dimensional control during manufacture and assembly and prevents stress concentration at the contact surface between a valve body seat and a valve box seat. The gate valve includes a valve body 2 having a valve body seat 23 and a valve body 3 having a valve body seat 31. a and the valve seat surface 31 of the valve body valve seat 31 a The valve disc seat 31 is a solid body that can move independently of the valve disc 3. The valve disc 3 comprises an annular recess 32 that houses the valve disc seat 31, a spring 33 that can urge the valve disc seat 31 toward the valve box seat 23 from inside the valve disc 3, and a spring accommodating portion 34 that accommodates the spring 33. A gap G formed between the annular recess 32 and the valve disc seat 31 forms an inflow path for the controlled fluid and ensures the expansion and contraction distance of the spring 33. The controlled fluid that flows into the gap G presses the valve disc seat 31 toward the valve box seat 23.

Description

[Technical Field]

[0001] This invention relates to a gate valve with a self-closing mechanism. [Background technology]

[0002] (Conventional gate valve) Gate valves are used to control fluids such as oil in industrial facilities such as refineries, petrochemical plants, chemical factories, thermal and hydroelectric power plants, and steel mills. Gate valves, also known as gate valves, are equipped with a valve disc that can open and close the fluid path, and the valve disc seat and valve box seat, which form the sliding surface between the valve disc and the internal flow path in the valve box, are inclined and wedge-shaped and face each other. When the valve disc closes the internal flow path, the valve disc is pressed in by the valve stem, and surface pressure is applied to the sliding surface so that the valve disc seat bites into the valve box seat, thereby stopping the fluid flowing through the internal flow path (see, for example, Figure 3 of Patent Document 1).

[0003] (Issues with conventional gate valves) As described above, in conventional check valves, the sliding surfaces of the valve body seat and the valve box seat are inclined in a wedge shape to slide in contact, so if the valve body was pushed in too far, there was a risk that part of the valve box would be damaged.

[0004] (Prior Art Configuration) To address these problems, the gate valve of Patent Document 1 employs a configuration in which at least one of the disc seat and the valve box seat, located upstream of the disc, is formed from a hollow metal elastic body, and an opening is provided in the metal elastic body that connects the internal space to the internal flow path of the valve box. With this configuration, the valve disc advances and retreats parallel to the seat surface of the valve box seat while the metal elastic body serving as the disc seat slides against the valve box seat, so that the pushing force applied to the valve does not act directly on the seat surfaces of the disc seat and the valve box seat, but acts as a force that elastically deforms the metal elastic body.

[0005] In addition, in the fully closed state where the valve disc seat and valve box seat are pressed together by the elastic force of the metal elastic body, the pressure of the controlled fluid upstream of the valve disc acts on the internal space of the metal elastic body through the opening, and this pressure acts as a force pressing the metal elastic body against the opposing valve seat from the inside. This fluid pressure, combined with the elastic force of the metal elastic body, increases the surface pressure, thereby increasing the water cut-off pressure.

[0006] As described above, Patent Document 1 describes a self-sealing structure (self-closing mechanism) that utilizes the elastic force of a metal elastic body and the pressure of a controlled fluid.

[0007] (Manufacturing problems with prior art) However, there are concerns that the gate valve with a metal elastic body disclosed in Patent Document 1 may have the following problems in manufacturing and use. First, the metal elastic body is assumed to be an annular body with a hollow cylindrical cross section, and it is practically difficult to manufacture an opening along the inner diameter side of the annular body that connects the internal space with the outside. Furthermore, as shown in Figure 2 of Patent Document 1, methods such as welding or adhesive bonding can be used to join the metal elastic body to the valve body, but it is difficult to control the strength and dimensions of the joint, and the larger the valve body, the more difficult it becomes to manage these factors.

[0008] Furthermore, in order for the metal elastomer to exhibit the self-sealing structure described above, the outer edge of the metal elastomer, which serves as the valve disc seat, must be in constant contact with the valve box seat, and it is believed that dimensional control during manufacturing and assembly would be nearly impossible.

[0009] (Problems with the use of prior art) In addition, when the annular metal elastic body comes into contact with the flat surface of the valve seat of the valve body seat, the two are, strictly speaking, in line contact, which may result in stress concentration at the contact point. If the stress concentration causes sliding scratches on the contact line, the differential pressure at the contact point cannot be maintained, and the self-sealing structure may easily fail. Furthermore, with line contact, excessive stress concentration occurs at the contact point, which may result in deformation beyond elastic deformation (i.e., plastic deformation such as buckling). This concern also calls into question the service life of the gate valve of Patent Document 1.

[0010] Furthermore, if a metal elastic body is provided downstream of the valve disc (in the flow direction of the controlled fluid), the hollow portion of the metal elastic body will be compressed and crushed by the water-stopping pressure that the valve disc receives from the fluid, and there is a high probability that the self-sealing structure described above will no longer function. For this reason, even if the metal elastic body of the prior art could be manufactured, it would be restricted to being installed only upstream of the valve disc. Furthermore, when a gate valve is placed in a path where the flow direction of the controlled fluid reverses, such as for use as a branch valve, a self-sealing structure (water-stopping structure) must be provided both upstream and downstream of the valve disc, and the gate valve of Patent Document 1 cannot be used for such purposes.

[0011] Perhaps due to the above manufacturing and practical problems and concerns, the inventors have not seen any prior art gate valves on the market. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] Japanese Utility Model Application Publication No. 06-078668 Summary of the Invention [Problem to be solved by the invention]

[0013] The purpose of this invention was to take these circumstances into consideration and provide a check valve with a self-closing mechanism that allows for easy dimensional control during manufacturing and assembly and is less likely to cause stress concentration at the contact surface between the valve body seat and the valve box seat.

[0014] Another object of the present invention is to provide a gate valve in which a self-sealing structure can be provided on both the upstream and downstream sides of the valve body. [Means for solving the problem]

[0015] After extensive research, the inventors discovered that by preparing a valve disc seat with a flat valve seat surface, separating this valve disc seat from the valve disc, and providing a spring inside the valve body that urges the valve disc seat from the back side toward the valve box seat, it is possible to provide the valve disc seat with a wide range of motion and achieve a structure that is less likely to cause stress concentration, thereby solving all of the above problems.

[0016] That is, the present invention has, for example, the following configurations and features. (Aspect 1) A gate valve comprising a valve box having a valve box valve seat and a valve disc having a valve disc valve seat, and wherein the valve disc valve seat is in sliding contact with the valve box valve seat when the valve disc moves in and out of the valve box, a valve seat surface of the valve body seat and a valve seat surface of the valve disc seat are flat; the valve body valve seat is a solid body that can move independently of the valve body, The valve body includes an annular recess that accommodates the valve body valve seat, a spring that can urge the valve body valve seat toward the valve box valve seat from the inside of the valve body, and a spring accommodating portion that accommodates the spring, a gap is formed between the annular recess and the valve seat of the valve body accommodated in the annular recess, The gap forms an inflow path for the controlled fluid and ensures the expansion and contraction distance of the spring, The controlled fluid that has flowed into the gap presses the valve body seat toward the valve body seat. A gate valve characterized by: (Aspect 2) A first O-ring capable of ensuring sealing between the valve body valve seat and the annular recess, and a first O-ring accommodating portion accommodating the first O-ring are provided on an outer peripheral wall of the valve body valve seat. 2. The gate valve according to claim 1, (Aspect 3) A second O-ring capable of ensuring sealing between the valve body seat and the valve box seat, and a second O-ring accommodating portion accommodating the second O-ring are provided on the valve seat surface of the valve body seat. The gate valve according to aspect 1 or 2, (Aspect 4) The valve body valve seat and the valve disc valve seat are provided on both the upstream side and the downstream side of the valve disc with respect to the flow direction of the controlled fluid. The gate valve according to aspect 1 or 2, (Aspect 5) The spring and the spring accommodating portion on the downstream side of the valve body are provided at a phase difference in the circumferential direction of the valve body from the spring and the spring accommodating portion on the upstream side of the valve body. 5. The gate valve according to claim 4, wherein: [Effects of the Invention]

[0017] According to the check valve of the present invention having the above-mentioned characteristics, the valve seat surface of the valve box valve seat and the valve seat surface of the valve disc valve seat are flat, so that the contact between the valve disc valve seat and the valve box valve seat is surface contact, making it possible to create a structure that is less likely to cause stress concentration and resulting sliding scratches.

[0018] In addition, in the gate valve of this invention, the valve seat of the valve disc can be moved independently of the valve disc, and a spring that biases the valve seat toward the valve box seat is provided inside the valve disc (behind the valve seat of the valve disc), giving the valve seat a wide range of movement. This not only makes it easier to control dimensions during manufacturing and assembly, but also allows the valve seat to be pressed against the valve box seat with an appropriate biasing force.

[0019] In addition to the above advantages, the valve disc and valve seat of this invention are made of a solid body and are highly rigid, so there is no risk of plastic deformation due to water-stopping pressure, as was a concern with prior art, and this contributes to a longer service life. This makes it possible to install self-sealing structures (pairs of valve disc and valve box seats) on both the upstream and downstream sides of the valve disc. For example, the gate valve of this invention can be installed in piping where the flow direction of the controlled fluid reverses. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a perspective view of a gate valve according to an embodiment of the present invention; [Figure 2] FIG. 1 is a perspective view of a gate valve with front components removed to show the internal structure. [Figure 3] FIG. 2 is a cross-sectional view showing the valve body and valve body in an assembled state as a check valve. [Figure 4] FIG. 2 is a partial cross-sectional view showing a portion of the valve body and valve disc when not subjected to fluid pressure. [Figure 5] FIG. 2 is a partial cross-sectional view showing a portion of the valve body and valve disc under fluid pressure. DETAILED DESCRIPTION OF THE INVENTION

[0021] The technical contents of the novel gate valve of the present invention will be explained below based on the following specific embodiments with reference to the accompanying drawings, but the present invention is not limited to these embodiments. In addition, the same reference numerals are used in each drawing to designate the same or corresponding elements. [Example]

[0022] (Overview of gate valve) Figure 1 shows a perspective view of a gate valve 1 according to one embodiment of the present invention, and Figure 2 shows a perspective view of the gate valve 1 with the front side components removed to show the internal structure. The gate valve 1 comprises, as its main components, a valve body 2 and a disc-shaped valve element 3. Figure 3 is a cross-sectional view showing the valve body 2 and valve element 3 in an assembled state as the gate valve 1.

[0023] (Valve box overview) The valve box 2 is composed of a body 21 and a valve element housing portion 22. The body 21 has an opening 21 which forms a flow path through which the controlled fluid can flow. a This opening 21 a The valve element 3 capable of blocking the flow of the controlled fluid is accommodated in a valve element accommodating space 22, which will be described later. a On the other hand, the valve body accommodating portion 22 has an opening 21 a a valve body accommodating space 22 in which the valve body 3 can be temporarily accommodated while the valve body 3 is opened to allow the controlled fluid to flow; a will be established.

[0024] (Valve body overview) Inside the valve box 2, an opening 21 aThe valve element 3 is arranged so as to be retractable in a direction crossing the opening 21. The valve element 3 is driven by a valve stem 4. The valve element 3 is located in the body 21 and has an opening 21. a a fully closed position in which the valve body is blocked, and a fully closed position in which the valve body is located in the valve body housing portion 22 and the opening 21 a The door opens and closes between the fully open position.

[0025] The valve disc 3 shown in Figures 1 and 2 is positioned intermediately between the fully closed and fully open positions. Figure 4 is a partial cross-sectional view showing a portion of the valve body 2 and valve disc 3 in the fully closed position without being subjected to pressure from the controlled fluid. Meanwhile, Figure 5 is a partial cross-sectional view showing a portion of the valve body 2 and valve disc 3 in the fully closed position while being subjected to pressure from the controlled fluid. Note that the terms "Up" and "Down" in Figure 5 indicate the upstream and downstream sides of the controlled fluid, the outline arrow indicates the flow direction of the controlled fluid, and the hatched arrow indicates the direction of movement of the valve disc 3. Furthermore, the dashed-dotted line in Figure 4 indicates the center line of the valve disc 3, but in Figure 5, the valve disc 3 has moved downstream due to fluid pressure, so the center line of the valve disc 3 (the dashed-dotted line on the left side of the figure) has moved to the left of its pre-movement center line (the dashed-dotted line on the right side of the figure).

[0026] (Sliding surface between the valve body and the valve disc) The sliding surfaces of the valve box 2 (body 21) and the valve disc 3 are formed by a valve box valve seat 23 and a valve disc valve seat 31 that face each other. a The valve seat surface 23 of the valve body seat 23 is in sliding contact with the central axis of the valve body 3. a The valve seat surface 31 of the valve body valve seat 31 a This makes it difficult for stress concentration and the resulting sliding scratches that were a concern in the prior art to occur.

[0027] (Practicality of prior art valve bodies and valve seats) As described above, the valve disc seat (metallic elastic body) in Patent Document 1 was integrally fixed to the valve disc by welding or the like, and therefore the dimensional control (processing precision) of each of these parts had to be maintained within an extremely narrow range (a range in which the valve disc seat would not undergo plastic deformation due to sliding contact with the valve box seat), which was at a level that was impossible for practical use.

[0028] (Ease of manufacturing the valve body and valve seat of this invention) Therefore, in this invention, a solid body that can move independently of the valve disc 3 is used as the valve disc seat 31 (see Figures 4 and 5). A solid body with a flat seat can be easily manufactured by machining. Furthermore, because such a solid valve disc seat 31 has high mechanical rigidity, it is less likely to undergo plastic deformation even when subjected to water-stopping pressure from the controlled fluid. Therefore, the water-stopping structure of this invention (the pair of the valve box seat 23 and the valve disc seat 31) can be installed either upstream or downstream of the valve disc 3 in the flow direction of the controlled fluid, as shown in Figures 4 and 5.

[0029] (Valve seat accommodation structure for valve body) In the present invention, the valve body 3 is provided with an annular recess 32 capable of accommodating the valve body seat 31, a spring 33 capable of urging the valve body seat 31 toward the valve body seat 23 from the inside of the valve body 3, and a spring accommodating portion 34 accommodating the spring 33. It is desirable that a plurality of springs 33 and spring accommodating portions 34 are installed at predetermined intervals along the ring (circumference) of the annular recess 32.

[0030] As described above, the valve seat 31 is separated from the valve body 3, and the back side of the valve seat 31 (the bottom 32 of the annular recess 32) b ), it is possible to provide a wide range of movement (travel distance) while applying a desired elastic force (pressing force against the valve body valve seat 23) to the valve disc valve seat 31. Note that although a compression coil spring is shown in Figures 4 and 5 as an example of the spring 33, the present invention is not limited to this and springs of other known structures may also be used.

[0031] (Self-sealing structure of this invention) It should also be noted that a gap G is formed between the annular recess 32 and the valve seat 31 of the valve body accommodated in the annular recess 32. Specifically, the inner peripheral wall 32 of the annular recess 32 a Side and bottom 32 b It is preferable that gaps G are formed on the sides of the spring 33. These gaps G form an inflow path for the controlled fluid and also ensure the extension distance of the spring 33.

[0032] The controlled fluid that has flowed into the gap G presses the valve disc valve seat 31 toward the valve body valve seat 23. The specific mechanism is as follows: By adopting a structure that allows the controlled fluid to enter the gap G, the inner peripheral wall 32 of the annular recess 32 in which the gap G is formed a Side and bottom 32 b The surface 31 of the valve seat 31 on the side b ,31 c The inflow pressure of the controlled fluid is directly applied to the valve.

[0033] On the other hand, the outer peripheral wall 32 of the annular recess 32 where the gap G is not formed c The surface 31 of the valve seat 31 on the side d and a valve seat surface 31 that comes into contact with the valve body seat 23. a Since the inflow of the controlled fluid is blocked at these surfaces 31 d ,31 a In this way, the valve disc seat 31 is pressed toward the valve body seat 23 by the difference in fluid pressure caused by the presence or absence of the gap G around the valve disc seat 31.

[0034] As described above, in the gate valve 1 of the present invention, the opening 21 of the valve box 2 is pressed by using not only the elastic force of the spring 33 but also the inflow pressure of the fluid itself. a The valve body 3 can self-close.

[0035] In order to ensure that the self-sealing structure functions reliably, it is preferable to adopt the following structure. Specifically, the outer wall 31 of the valve body valve seat 31 d The valve seat 31 of the valve element is provided with a first O-ring R1 that can ensure sealing (watertightness and airtightness) between the valve seat 31 and the annular recess 32, and a first O-ring receiving portion 35 that receives the first O-ring R1. a is provided with a second O-ring R2 that can ensure sealing between the valve disc valve seat 31 and the valve body valve seat 23, and a second O-ring accommodating portion 36 that accommodates the second O-ring R2.

[0036] By providing the first and second O-rings R1 and R2 on the valve seat 31, the outer peripheral wall 31 of the valve seat 31 isd and the annular recess 32, and the valve seat surface 31 between the valve body valve seat 31 and the valve box valve seat 23. a ,twenty three a It is possible to improve the sealing between the parts.

[0037] This more reliably generates a pressure difference between the inflow pressure in the gap G where the controlled fluid is introduced into the annular recess 32 and the pressure of the controlled fluid that has no inflow pressure and is blocked by the first and second O-rings R1, R2, making it possible to maintain for a longer period of time and more reliably the self-sealing structure that presses the valve body valve seat 31 against the valve box valve seat 23 to stop the controlled fluid from flowing.

[0038] In addition, the valve box valve seat 23 may also be provided with a valve box valve seat O-ring accommodating portion 24 that accommodates a valve box valve seat O-ring R3 that can ensure airtightness between the valve box valve seat 23 and the valve box 2 (main body portion).

[0039] The self-sealing structure of the present invention, which is composed of a pair of a valve box valve seat 23 and a valve body valve seat 31, may be provided on either the upstream or downstream side of the valve body 3 in the flow direction of the controlled fluid, but providing it on both sides makes it possible to use the check valve 1 of the present invention in applications such as branch valves and piping where the flow direction of the controlled fluid is reversed.

[0040] Furthermore, if the self-sealing structure of the present invention is installed both upstream and downstream, each self-sealing structure must have a spring accommodating section 34 at the back of the annular recess 32. If the spring accommodating sections 34 are provided at corresponding positions (in the same phase) along the ring (circumference) of the annular recess 32, the thickness of the valve body 3 must be increased to avoid contact between the spring accommodating sections 34, 34.

[0041] Therefore, if the spring 33 and spring accommodating portion 34 on one side (downstream side) of the valve body 3 are arranged so as to have a phase difference in the circumferential direction of the valve body 3 from the spring 33 and spring accommodating portion 34 on the other side (upstream side) of the valve body 3 (their circumferential positions are shifted from each other), it becomes possible to avoid increasing the thickness of the valve body 3. Note that in Figures 4 and 5, the downstream spring 33 and spring accommodating portion 34 do not have a phase difference in the circumferential direction from the upstream spring 33 and spring accommodating portion 34.

[0042] (Problems caused by pipe repairs) The pipes in which the gate valve 1 is installed are generally made of metal, and deteriorate over the course of several decades, sometimes requiring repair. Repairs often involve cutting a section of the pipe and connecting a new pipe by welding or other methods, which can result in changes in the length and other dimensions of the pipe. This expansion and contraction of the pipe length can impart expansion and contraction stress to the gate valve 1, potentially distorting the valve body seat 23.

[0043] The gate valve 1 of the present invention has a valve disc seat 31 that has a wide range of movement relative to the valve body seat 23, so even if the position of the valve body seat 23 shifts slightly due to the expansion and contraction of the piping, this can be tolerated while applying an appropriate elastic force to the valve body seat 23. In other words, the gate valve 1 of the present invention can maintain good valve opening and closing operation and self-closing function regardless of whether the piping is repaired or not.

[0044] Although the gate valve 1 of the present invention has been described based on the above embodiment, the scope of the present invention is not necessarily limited to this embodiment. For example, in this embodiment, the spring 33 and the spring accommodating portion 34 are installed inside the valve body 3, but they may also be installed inside the body 21 of the valve box 2. [Industrial Applicability]

[0045] According to the check valve of the present invention having the above-mentioned characteristics, the valve seat surface of the valve box valve seat and the valve seat surface of the valve disc valve seat are flat, so that the contact between the valve disc valve seat and the valve box valve seat is surface contact, making it possible to create a structure that is less likely to cause stress concentration and resulting sliding scratches.

[0046] In addition, in the gate valve of this invention, the valve seat of the valve disc can be moved independently of the valve disc, and a spring that biases the valve seat toward the valve box seat is provided inside the valve disc (behind the valve seat of the valve disc), giving the valve seat a wide range of movement. This not only makes it easier to control dimensions during manufacturing and assembly, but also allows the valve seat to be pressed against the valve box seat with an appropriate biasing force.

[0047] In addition to the above advantages, the valve disc and valve seat of this invention are made of a solid body and are highly rigid, so there is no risk of plastic deformation due to water-stopping pressure, as was a concern with prior art, and this contributes to a longer service life. This makes it possible to install self-sealing structures (pairs of valve disc and valve box seats) on both the upstream and downstream sides of the valve disc. For example, the gate valve of this invention can be installed in piping where the flow direction of the controlled fluid reverses.

[0048] As such, the gate valve of the present invention has extremely high industrial applicability and utility value. [Explanation of symbols]

[0049] 1. Gate valve 2, 3, 4 Valve body, valve disc, valve stem 21,21 a Valve body and opening 22,22 a Valve body storage area, valve body storage space 23,23 a Valve box seat, valve seat surface of valve box seat 24 Valve body valve seat O-ring housing 31,31 a ,31 b ,31 c ,31 d Valve seat, valve seat surface of valve seat, other surfaces 32,32 a ,32 b ,32 c Annular recess, inner peripheral wall, bottom, and outer peripheral wall of the annular recess 33 Spring 34 Spring housing 35, 36 First O-ring receiving portion, second O-ring receiving portion G Gap R1, R2, R3 1st O-ring, 2nd O-ring, O-ring for valve body and valve seat

Claims

1. A gate valve comprising a valve body having a valve body seat and a valve body having a valve body seat, and wherein the valve body seat is in sliding contact with the valve body seat when the valve body moves in and out of the valve body, a valve seat surface of the valve body seat and a valve seat surface of the valve disc seat are flat; the valve body valve seat is a solid body that can move independently of the valve body, The valve body includes an annular recess that accommodates the valve body valve seat, a spring that can urge the valve body valve seat toward the valve box valve seat from the inside of the valve body, and a spring accommodating portion that accommodates the spring, a gap is formed between the annular recess and the valve seat of the valve body accommodated in the annular recess, The gap forms an inflow path for the controlled fluid and ensures an expansion and contraction distance of the spring, The controlled fluid that has flowed into the gap presses the valve body valve seat toward the valve body valve seat. A gate valve characterized by:

2. A first O-ring capable of ensuring sealing between the valve body valve seat and the annular recess and a first O-ring accommodating portion accommodating the first O-ring are provided on an outer peripheral wall of the valve body valve seat.

2. The gate valve according to claim 1 .

3. A second O-ring capable of ensuring sealing between the valve body seat and the valve box seat, and a second O-ring accommodating portion accommodating the second O-ring are provided on the valve seat surface of the valve body seat.

3. The gate valve according to claim 1 or claim 2.

4. The valve body valve seat and the valve disc valve seat are provided on both the upstream side and the downstream side of the valve disc with respect to the flow direction of the controlled fluid.

3. The gate valve according to claim 1 or claim 2.

5. The spring and the spring accommodating portion on the downstream side of the valve body are provided at a phase difference in the circumferential direction of the valve body from the spring and the spring accommodating portion on the upstream side of the valve body.

5. The gate valve according to claim 4.

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