non-return valve

Abstract

To provide a check valve having a high degree of freedom on an installation site for preventing the occurrence of perforation in a valve box.SOLUTION: The check valve includes the valve box having a flow path formed inside where fluid flows, a valve element 12 arranged in the valve box, and a straightening plate 14 arranged in the valve box and on the upstream side of the valve element. The straightening plate has smaller fluid resistance in a center area than in an edge area. The straightening plate has a plurality of holes 16. The hole in the center area of the flow path preferably has a larger diameter than that in the edge area, or the plurality of holes can be arranged in the straightening plate so that the number of holes per unit area is further increased in the center area than in the edge area.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a check valve. [Background technology]

[0002] A check valve opens its valve disc when fluid flows in the forward direction, and closes to block the flow path when fluid tries to flow in the reverse direction, preventing backflow. In piping systems where a check valve is installed, fluid can experience drift, separation, or swirling flow when passing through bends in the flow path upstream of the check valve (elbows, bends, or tees) or expansions in the flow path (reducers, etc.). When fluid flows into the check valve with drift, separation, or swirling flow, the pressure inside the check valve fluctuates over time, causing the valve disc to repeatedly open and close (chattering), or the fluid force acting on the valve disc can cause it to fall off. Another problem is that drift, separation, and swirling flow can cause droplets and fine particles in the fluid to repeatedly collide with the valve body, resulting in holes in the valve body.

[0003] Therefore, a sufficiently long straight pipe is placed upstream of the check valve and connected to it, and as the fluid passes through the straight pipe, the uneven flow, separated flow, and swirling flow of the fluid are attenuated, thereby preventing chattering and detachment of the valve disc. Here, a "sufficiently long straight pipe" means, for example, a straight pipe length of 5D or more, where D is the diameter of the pipe. Taking into account the limitations on placement due to the long length, the length is specifically about 5D to 10D.

[0004] In order to connect a sufficiently long straight pipe upstream of a check valve, it is necessary to secure installation space for the straight pipe upstream of the check valve. However, due to restrictions on piping installation space, it can be difficult to place a long straight pipe upstream of the check valve. In other words, in places where there is no space to install a straight pipe, it is difficult to install a check valve, and there is an issue that the installability of the check valve is impaired.

[0005] Therefore, Patent Document 1 proposes connecting a short pipe flange with an internal flow straightening grid to the upstream side of the valve disc. Patent Document 1 discloses that when the fluid passes through the flow straightening grid of the short pipe flange, the swirling flow and turbulent flow of the fluid can be straightened, thereby preventing chattering of the valve disc. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 10-103541 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the check valve described in Patent Document 1 requires that space be secured for installing a short pipe flange upstream of the check valve, and there is a risk that it cannot be installed if there is no space for installing the short pipe flange.

[0008] Furthermore, when the fluid flowing through the piping system is a gas such as steam or air and contains droplets or fine powder, the droplets or fine powder in the fluid that flows into the inside of the check valve may collide with the valve box (housing) of the check valve, damaging or thinning the valve box and causing holes in the valve box; however, this is not particularly taken into consideration in Patent Document 1.

[0009] The present invention has been made to solve the above-mentioned problems, and its main object is to provide a check valve that prevents holes from forming in the valve body and has a high degree of freedom in terms of installation location. [Means for solving the problem]

[0010] In order to achieve the above object, the present invention provides a check valve comprising: a valve body having a flow path formed therein for allowing a fluid to flow; a valve element disposed inside the valve body; and a flow rectifier disposed inside the valve body and upstream of the valve element, The straightening plate has a plurality of holes on the plate surface, and the plurality of holes are formed so that at least one of the hole diameter, hole density, or length in the plate thickness direction of the holes formed in the central part of the straightening plate has a smaller fluid resistance than the corresponding value of the holes formed in the edge part of the straightening plate, The flow plate has a smaller fluid resistance at the center than at the edge. It is designed toThe composition is as follows. Other means will be described later. [Effects of the Invention]

[0011] According to the present invention, a check valve can be provided which prevents chattering or detachment of the valve disc and holes in the valve body, and which has a high degree of freedom in terms of installation location. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a diagram of a check valve according to a first embodiment. [Figure 2] FIG. 1 is a diagram of a flow rectifier plate used in a check valve. [Figure 3] FIG. 10 is a diagram of a straightening plate according to a first modified example. [Figure 4A] FIG. 1 is a diagram (1) of a straightening plate according to a second modified example. [Figure 4B] FIG. 2 is a diagram (2) of the straightening plate of the second modified example. [Figure 5A] FIG. 1 is a diagram (1) of a straightening plate according to a third modified example. [Figure 5B] FIG. 10 is a diagram (2) of the straightening plate of the third modified example. [Figure 6] FIG. 10 is a diagram of a check valve according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, an embodiment of the present invention (hereinafter referred to as "the present embodiment") will be described in detail with reference to the drawings. Note that each drawing is a schematic illustration to the extent that the present invention can be fully understood, and the present invention is not limited to the illustrated examples. Furthermore, in each drawing, common or similar components are given the same reference numerals, and redundant explanations thereof will be omitted.

[0014] [Embodiment 1] <Check valve configuration> The check valve according to the first embodiment will be described below with reference to Figures 1 and 2. Figure 1 is a diagram of a check valve 10 according to the first embodiment. Figure 2 is a diagram of a flow straightening plate 14 used in the check valve 10, showing the appearance of the flow straightening plate 14 as seen from the upstream side (left direction in Figure 1).

[0015] 1, the check valve 10 according to this embodiment includes a valve body 11, a valve element 12, a valve seat 13, and a flow rectifying plate 14. The check valve 10 according to this embodiment is a swing-type check valve in which the valve element 12 rotates by a predetermined angle around a hinge pin 15 provided at the upper portion of the valve element 12 inside the valve element installation space 11a.

[0016] The valve box 11 is a housing having a flow path formed therein through which a fluid flows. In FIG. 1, arrows indicate the flow of the fluid. The valve box 11 has a valve disc installation space 11a therein in which a valve disc 12 is installed. The valve box 11 also has a valve seat installation portion 11b in which a valve seat 13 is installed, in the flow path portion facing the valve disc installation space 11a. The valve box 11 also has a stopper portion 11c at the portion that comes into contact with the valve disc 12 when it is pushed up, which stops the valve disc 12 when it is pushed up.

[0017] The valve element 12 is a member that is disposed inside the valve box 11 and opens and closes the flow path.

[0018] The valve seat 13 is a member that receives the valve element 12 that moves in the direction to close the flow path when the fluid flows backward (when the fluid flows from right to left in the example shown in FIG. 1). For example, it is an annular member that is provided along the inner wall of the valve box, and closes the flow path when its opening comes into close contact with the valve element.

[0019] The flow straightening vane 14 is a component that straightens the flow of the fluid when it flows in the correct direction (when the fluid flows from left to right in the example shown in FIG. 1). The flow straightening vane 14 is provided inside the valve body and has a shape that corresponds to the cross section of the flow path. The flow straightening vane 14 is preferably provided upstream of the valve disc.

[0020] As shown in Figures 1 and 2, a plurality of holes are formed in the plate surface of the rectifying plate 14. Figure 2 is a diagram of the rectifying plate 14. In this embodiment, the rectifying plate 14 is installed inside the opening of the valve seat 13, and therefore, as shown in Figure 2, the outer shape of the rectifying plate 14 is shaped so that it can be installed on the valve seat 13 without any gaps. In other words, the rectifying plate 14, which is fixed to the annular valve seat, has a disk-like shape.

[0021] The flow rectifying plate 14 has a smaller fluid resistance (the force that the flow rectifying plate receives from the fluid as the fluid passes through it) in the center portion than in the edge portion of the disk (the portion closer to the outer edge than the center position between the center position and the outer edge of the flow rectifying plate). In the example shown in Fig. 2, the diameters of the multiple holes are not uniform, and the flow rectifying plate 14 has multiple holes 16 formed so that the diameter increases toward the center. In other words, the diameters of the multiple holes 16 formed in the center portion of the flow rectifying plate 14 are larger than the holes formed in the edge portion of the flow rectifying plate 14.

[0022] When the fluid flows in the correct direction (from left to right in Figure 1), the fluid enters the valve box 11 from its inlet (opening on the left side) and passes through the flow straightener 14 installed inside the valve seat 13. The flow straightener 14 has multiple holes 16 arranged in it. Therefore, as the fluid passes through the flow straightener 14, the flow component parallel to the flow straightener 14 is suppressed, and the drift, separation flow, and swirling flow of the fluid are attenuated.

[0023] Furthermore, the multiple holes 16 in the current vane 14 are formed so that their diameters increase toward the center. Therefore, when the fluid passes through the current vane 14, the fluid resistance acting on the current vane 14 is smaller in the center than in the edge portions of the current vane 14. In other words, the fluid flows more easily in the center than in the edge portions of the current vane 14. Therefore, when the fluid passes through the current vane 14, the flow rate of the fluid that flows into the check valve 10 is greater in the center of the current vane 14 than in the edge portions.

[0024] As a result, the fluid that flows into the check valve 10 is distributed in a cross section perpendicular to the flow path (hereinafter referred to as the "vertical cross section") such that the fluid is more concentrated at the center of the pipe axis and less concentrated near the inner surface of the valve body. This makes it possible to generate an uneven fluid distribution in the vertical cross section, preventing droplets and fine powder in the fluid from colliding with the valve body and preventing holes from forming in the valve body 11.

[0025] On the other hand, when a straightening plate with multiple holes evenly arranged is used, as in the check valve described in Patent Document 1, it is thought that the distribution of the fluid that has passed through the short pipe flange will be uniform in a cross section perpendicular to the direction of fluid flow inside the check valve (hereinafter referred to as the "vertical cross section"). As a result, droplets will exist at a uniform density on the vertical cross section, and droplets present near the wall surface inside the valve body will collide with the wall surface, making it easier for thinning to occur.

[0026] In this embodiment, by distributing the fluid unevenly in the central part of the vertical cross section, more droplets are present in the central part, and the proportion of droplets present near the wall surface inside the valve box is reduced, thereby reducing the frequency with which droplets collide with the wall surface and suppressing the occurrence of thinning.

[0027] Next, the operation of the check valve 10 according to this embodiment will be described assuming that the valve element 12 is initially received by the valve seat 13. The fluid that has passed through the rectifying plate 14 strikes the first surface 12a of the valve element 12, the surface of the valve element 12 facing the valve seat 13 (the left surface in FIG. 1 ). When pressured by the fluid striking the first surface 12a, the valve element 12 rotates counterclockwise around the hinge pin 15 as an axis, moves away from the valve seat 13, and strikes the stopper portion 11c, stopping. This opens the flow path connecting the inlet side to the outlet side of the check valve 10. The fluid that strikes the first surface 12a of the valve element 12 flows out of the valve box 11 through the outlet (the opening on the right side) of the valve box 11.

[0028] On the other hand, when the fluid flows backward (when the fluid flows from right to left in FIG. 1), the fluid flows into the valve box 11 from the outlet (the opening on the right side) of the valve box 11 and hits the second surface 12b of the valve disc 12 (the surface on the right side, the outlet side of the valve box 11 in FIG. 1). When the second surface 12b receives pressure from the fluid, the valve disc 12 rotates clockwise around the hinge pin 15 as an axis, separates from the stopper portion 11c, and hits the valve seat 13, stopping. This blocks the flow path, and the check valve 10 prevents the fluid from flowing backward.

[0029] When the fluid flows in the correct direction (from left to right in FIG. 1 ), the fluid's drift, separation, and swirling flow are attenuated as it passes through the straightening vane 14. This prevents chattering and detachment of the valve element 12 in the check valve 10 of this embodiment. Furthermore, as the fluid passes through the straightening vane 14, the fluid resistance acting on the straightening vane 14 is smaller at the center than at the edges of the straightening vane 14, and the fluid is distributed around the pipe axis in a vertical cross section (a cross section perpendicular to the flow of the fluid that has flowed into the check valve 10). This allows the check valve 10 to generate a non-uniform fluid distribution in the vertical cross section. Because droplets and fine particles in the fluid move along the fluid flow, distributing the fluid around the pipe axis effectively prevents collisions between the droplets and fine particles that have flowed into the check valve 10 and the valve body 11. This prevents holes from forming in the valve body 11 of the check valve 10.

[0030] Furthermore, the check valve 10 attenuates drift, separated flow, and swirling flow of the fluid with the flow straightener 14 installed inside the valve seat 13, and there is no need to secure installation space for installing a sufficiently long straight pipe or short pipe flange upstream of the check valve 10. Such a check valve 10 can be installed without arranging a sufficiently long straight pipe or short pipe flange upstream of the check valve 10.

[0031] <Modification of the rectifying plate> The following describes modified examples of the current plate 14. A first modified example (current plate 14A) is shown in Fig. 3, a second modified example (current plate 14B) is shown in Figs. 4A and 4B, and a third modified example (current plate 14C) is shown in Figs. 5A and 5B.

[0032] Fig. 3 is a diagram showing a flow straightening plate 14A of a first modified example as seen from the upstream direction. As shown in Fig. 3, the flow straightening plate 14A of the first modified example has a circular plate shape. The flow straightening plate 14A of the first modified example has a plurality of holes 16 arranged so that the number of holes per unit area increases from the edge portion to the center portion. As a result, the fluid resistance of the flow straightening plate is small at the center of the pipe axis and large near the inner surface of the valve body, so that the fluid that flows into the inside of the check valve 10 is distributed in a large amount at the center of the pipe axis and small near the inner surface of the valve body.

[0033] 4A and 4B are diagrams of a second modified example of a current plate 14B. Fig. 4A shows the current plate 14B as viewed from the upstream direction. Fig. 4B shows a cross section of the current plate 14B as viewed from a direction perpendicular to the flow path.

[0034] 5A and 5B are views of a flow rectifying plate 14C according to a third modified example. Fig. 5A shows the flow rectifying plate 14C as viewed from the upstream direction. Fig. 5B shows a cross section of the flow rectifying plate 14C as viewed from a direction perpendicular to the flow path.

[0035] 4 and 5, the current plates 14B and 14C of the second and third modified examples are disk-shaped and have a plurality of holes 16 on the plate surface. The current plate 14B of the second modified example has concave surfaces on both sides, while the current plate 14C of the third modified example has one concave surface (the left surface in the example shown in FIG. 5B) and the other flat surface (the right surface in the example shown in FIG. 5B). As a result, the current plate 14B of the second modified example and the current plate 14C of the third modified example become thinner from the edge portion toward the center portion of the current plate.

[0036] The first modified flow plate 14A shown in Fig. 3, the second modified flow plate 14B shown in Fig. 4A and Fig. 4B, and the third modified flow plate 14C shown in Fig. 5A and Fig. 5B all have a thinner central portion than the edge portions. As a result, the fluid resistance of the flow plate is small at the center of the pipe axis and large near the inner surface of the valve body, so that the fluid that flows into the check valve 10 is distributed in a large amount at the center of the pipe axis and small near the inner surface of the valve body.

[0037] Therefore, similar to the flow rectifier 14 (see FIG. 2), the flow rectifiers 14A, 14B, and 14C can all distribute the fluid around the pipe axis in a vertical cross section (a cross section perpendicular to the flow of the fluid that has flowed into the check valve 10) when the fluid passes through. Therefore, by using these flow rectifiers 14A, 14B, and 14C, the check valve 10 can generate a non-uniform fluid distribution in a vertical cross section, similar to the flow rectifier 14 (see FIG. 2), thereby preventing droplets and fine powder in the fluid from colliding with the valve box and preventing holes from forming in the valve box 11.

[0038] <Main features of check valves> (1) As shown in Figure 1, a check valve 10 according to this embodiment includes a valve box 11 having a flow path formed therein for flowing a fluid, a valve element 12 disposed inside the valve box 11, and a flow rectifier 14 disposed inside the valve box 11 upstream of the valve element 12. The flow rectifier 14 has a smaller fluid resistance at its center than at its edge.

[0039] The check valve 10 according to this embodiment can be installed in piping, and the flow straightening vane 14 attenuates the drift, separated flow, and swirling flow of the fluid that flows into the check valve 10, without the need to place a sufficiently long straight pipe or short pipe flange upstream of the check valve 10. Furthermore, the check valve 10 according to this embodiment can generate a non-uniform fluid distribution in the vertical cross section as the fluid passes through the flow straightening vane 14, effectively preventing collisions between the valve body 11 and droplets or fine powder in the fluid that flows into the check valve 10. Therefore, the check valve 10 according to this embodiment can prevent chattering or detachment of the valve disc 12 and holes in the valve body 11.

[0040] (2) As shown in Figure 2, the straightening plate 14 in this embodiment has a shape corresponding to the flow path cross section of the valve box 11 and has multiple holes 16 on the plate surface, and the multiple holes 16 are preferably configured so that the diameter of the holes formed in the center part of the flow path of the straightening plate 14 is larger than the diameter of the holes formed in the edge part of the straightening plate 14.

[0041] The flow straightening vane 14 according to this embodiment has lower fluid resistance in the center than in the edge portions. Therefore, when the fluid passes through the flow straightening vane 14, uneven fluid distribution occurs near the inner surface of the valve body in the vertical cross section of the check valve 10 and in the central portion of the pipe axis, effectively preventing droplets and fine powder in the fluid that has flowed into the check valve 10 from colliding with the valve body 11. Therefore, by using the flow straightening vane 14, the check valve 10 according to this embodiment can prevent chattering or detachment of the valve disc 12 and holes in the valve body 11.

[0042] (3) As shown in FIGS. 3 to 5B, the check valve 10 according to this embodiment may use rectifying plates 14A, 14B, and 14C instead of the rectifying plate 14 (see FIG. 2). The rectifying plate 14A shown in FIG. 3 has a circular plate shape, and a plurality of holes are arranged on the plate surface so that the number of holes per unit area increases toward the center. The rectifying plate 14B shown in FIGS. 4A and 4B and the rectifying plate 14C shown in FIGS. 5A and 5B both have a circular plate shape that becomes thinner from the edge toward the center, and a plurality of holes 16 are arranged on the plate surface. The rectifying plate 14B shown in FIGS. 4A and 4B has both concave surfaces. On the other hand, the rectifying plate 14C shown in FIGS. 5A and 5B has one concave surface and the other flat surface.

[0043] The flow rectifying plates 14A, 14B, and 14C all have lower fluid resistance in the center than in the edge portions. Therefore, like the flow rectifying plate 14 (see FIG. 2), the flow rectifying plates 14A, 14B, and 14C can distribute the fluid around the center of the pipe axis in a vertical cross section (a cross section perpendicular to the flow of the fluid that has flowed into the check valve 10) when the fluid passes through. By using such flow rectifying plates 14A, 14B, and 14C, collisions between the valve body 11 and droplets or fine powder in the fluid that has flowed into the check valve 10 can be effectively avoided, just like when the flow rectifying plate 14 (see FIG. 2) is used. Therefore, the check valve 10 according to this embodiment can prevent chattering or detachment of the valve disc 12 and holes in the valve body 11.

[0044] (4) As shown in Fig. 1, the check valve 10 according to this embodiment is provided with a valve seat 13 that comes into close contact with the valve element 12 when the flow path is closed, and the flow straightening plate 14 is preferably fixed to the valve seat 13. The flow straightening plate 14 may be manufactured by integral molding with the valve seat 13, or may be molded separately from the valve seat 13 and attached to the valve seat 13.

[0045] The check valve 10 according to this embodiment is easy to manufacture because the flow rectifying plate 14 can be installed on the valve body 11 by installing the valve seat 13 on the valve body 11.

[0046] (5) As shown in Fig. 1, the check valve 10 according to this embodiment is preferably a swing-type check valve in which the valve element 12 rotates at a predetermined angle around a hinge pin 15 provided at the upper portion of the valve element 12. The flow rectifying plate 14 of the check valve 10 according to this embodiment is preferably disposed at an incline so that its lower portion in the vertical direction is closer to the valve element 12.

[0047] In the check valve 10 according to this embodiment, the flow straightening plate 14 is arranged at an angle, so that when the check valve 10 is closed, gravity on the valve element contributes to the valve closing operation, thereby ensuring the closure of the flow path. Furthermore, when the fluid flows in the correct direction (from left to right in FIG. 1), the movement distance of the valve element 12 to the open position is short, so the check valve 10 according to this embodiment can quickly open the flow path.

[0048] As described above, the check valve 10 according to this embodiment 1 can be installed without placing a sufficiently long straight pipe or short pipe flange upstream, and can prevent chattering or detachment of the valve body 12 and holes in the valve box 11.

[0049] [Embodiment 2] The check valve 10 (see FIG. 1) according to the first embodiment is a swing-type check valve. In contrast, in the second embodiment, a lift-type check valve 10A will be described.

[0050] As shown in FIG. 6, the check valve 10A according to this embodiment is a lift-type check valve including a valve body 21, a valve element 22, a valve seat 23, and a flow rectifying plate 14 (see FIG. 2).

[0051] The valve box 21 is a housing having a flow path formed therein through which a fluid flows. In Fig. 6, arrows indicate the flow of the fluid. The valve box 21 has a valve disc installation space 21a therein in which the valve disc 22 is installed. The valve box 21 also has a valve seat installation portion 21b in which the valve seat 23 is installed, in the flow path portion facing the valve disc installation space 21a. The valve box 21 also has a guide portion 21c into which a protrusion 22c provided on a second surface 22b, which is the upper surface of the pushed-up valve disc 22, is inserted.

[0052] The valve element 22 is a member disposed inside the valve box 21 and opens and closes the flow path. In this embodiment, the valve element 22 is disposed so as to move up and down inside the valve box 21 by its own weight to close the flow path. A protrusion 22c that is inserted into a guide portion 21c of the valve box 21 is provided on the upper surface (second surface 22b) of the valve element 22.

[0053] The valve seat 23 is a member that receives the valve element 22 that moves in a direction that closes the flow path when the fluid flows backward (in the example shown in FIG. 6, when the fluid flows from the right side to the left side of the valve body 21). A rectifying plate 14 (see FIG. 2) is disposed inside the valve seat 23. The rectifying plate 14 may be manufactured by integral molding with the valve seat 23, or may be molded separately from the valve seat 23 and attached to the valve seat 23. The check valve 10A may use rectifying plates 14A, 14B, 14C (see FIGS. 3 to 5B) instead of the rectifying plate 14 (see FIG. 2).

[0054] Next, the operation of the check valve 10A according to this embodiment will be described.

[0055] When the fluid flows in the correct direction (when the fluid flows from left to right in the example shown in FIG. 6 ), the fluid flows into the valve box 21 from the inlet (opening on the left side) of the valve box 21 and passes through the straightening vane 14. The straightening vane 14 has a plurality of holes 16 arranged therein. Therefore, when the fluid passes through the straightening vane 14, the flow component parallel to the straightening vane 14 is suppressed, and the drift, separated flow, and swirling flow of the fluid are attenuated.

[0056] The fluid that has passed through the rectifying plate 14 hits the first surface 12a of the valve disc 22. The first surface 22a is the surface of the valve disc 22 that faces the valve seat 23 (the lower surface in FIG. 6). The valve disc 22 rises due to the pressure of the fluid hitting the first surface 22a, and stops when it hits the inner wall surface of the valve box 11. This opens the flow path that connects the rectifying plate 14 to the valve disc installation space 21a. The fluid that hits the first surface 22a of the valve disc 22 flows out of the valve box 21 from the outlet of the valve box 21 (the opening on the right side).

[0057] On the other hand, when the fluid flows backward (when the fluid flows from the right side to the left side in the example shown in FIG. 6), the fluid flows into the valve box 21 from the outlet (the opening on the right side) of the valve box 21 and hits the second surface 22b (the upper surface of the valve body 22) of the valve body 22. The valve body 22 is subjected to the pressure of the fluid on the second surface 22b, and is caused to descend and stop when it hits the valve seat 23. This blocks the flow path connecting the valve body installation space 21a to the rectifying plate 14, and the check valve 10A prevents the fluid from flowing backward.

[0058] When the fluid flows in the correct direction (from left to right in the example shown in FIG. 6 ), the uneven flow, separation, and swirling flow of the fluid are attenuated as the fluid passes through the flow straightener 14. This allows the check valve 10A to prevent the valve element 22 from moving up and down in small increments. Furthermore, when the fluid passes through the flow straightener 14, the fluid resistance acting on the flow straightener 14 is smaller at the center than at the edges of the flow straightener 14, and the fluid is distributed around the center of the pipe axis in a vertical cross section (a cross section perpendicular to the flow of the fluid that has flowed into the check valve 10A). This allows the flow straightener 14 to generate a non-uniform fluid distribution in the vertical cross section. This non-uniform fluid distribution effectively prevents droplets and fine particles in the fluid that have flowed into the check valve 10A from colliding with the valve body 21, thereby preventing holes from forming in the valve body 21.

[0059] Furthermore, check valve 10A attenuates drift, separated flow, and swirling flow of the fluid with straightening plate 14 installed inside valve seat 23, and it is not necessary to secure installation space for installing a sufficiently long straight pipe or short pipe flange upstream of check valve 10A. Such check valve 10A can be installed without arranging a sufficiently long straight pipe or short pipe flange upstream of check valve 10A.

[0060] As described above, the check valve 10A according to this embodiment 2 can be installed without placing a sufficiently long straight pipe or short pipe flange on the upstream side, and the valve body 22 can be prevented from moving up and down in small increments, and holes can be prevented from forming in the valve box 21.

[0061] The present invention is not limited to the above-described embodiments and includes various modifications. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of the embodiments with other configurations, and it is also possible to add other configurations to the configuration of the embodiments. Furthermore, it is possible to add, delete, or replace part of each configuration with other configurations. [Explanation of symbols]

[0062] 10,10A Check valve (10: Swing type check valve, 10A: Lift type check valve) 11,21 Valve box 11a, 21a Valve body installation space 11b,21b Valve seat installation part 11c Stopper part 12,22 Valve body 12a,22a 1st page 12b,22b 2nd side 12c Butt part 13,23 Valve seat 14,14A,14B,14C rectifier plate 15 Hinge pin 16 holes 21c Guide section 22c protrusion

Claims

1. a valve body having a flow path formed therein for flowing a fluid; a valve body disposed inside the valve body; a flow rectifier disposed upstream of the valve body inside the valve body, The rectifying plate has a plurality of holes on a plate surface, The plurality of holes are formed so that at least one of the hole diameter, hole density, or length in the plate thickness direction of the holes formed in the central portion of the straightening plate has a smaller fluid resistance than the corresponding value of the holes formed in the edge portion of the straightening plate, and thus the straightening plate is configured so that the fluid resistance in the central portion is smaller than the fluid resistance in the edge portion. A check valve characterized by:

2. The check valve according to claim 1, The flow straightening plate has a shape corresponding to the flow path cross section of the valve body and has a plurality of holes on the plate surface, The diameter of the holes formed in the center portion of the flow path of the straightening plate is larger than the diameter of the holes formed in the edge portion of the straightening plate. A check valve characterized by:

3. The check valve according to claim 1, The flow rectifier plate is fixed to a circular valve seat and has a disk-like shape. A check valve characterized by:

4. The check valve according to claim 1, The rectifying plate has a disk shape and has a plurality of holes on a plate surface, The plurality of holes are arranged so that the number of holes per unit area increases from the edge portion toward the center portion of the straightening plate. A check valve characterized by:

5. The check valve according to claim 1, The straightening plate has a disk shape, has a plurality of holes on the plate surface, and is thinner at the center than at the edge. A check valve characterized by:

6. The check valve according to any one of claims 1 to 5, a valve seat that comes into close contact with the valve body when the flow path is closed; The flow plate is fixed to the valve seat. A check valve characterized by:

7. The check valve according to any one of claims 1 to 6, The valve body is a swing-type check valve that rotates around a hinge pin provided at the upper part of the valve body. A check valve characterized by:

8. The check valve according to claim 7, The straightening plate is disposed at an incline so that the lower portion in the vertical direction is closer to the valve body. A check valve characterized by:

9. The check valve according to any one of claims 1 to 6, The valve element is a lift-type check valve that is arranged so as to move up and down. A check valve characterized by:

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