Check valve

Abstract

To provide a check valve that has a high Cv value while suppressing the generation of fluid turbulence.SOLUTION: In the check valve (1), a valve body (30) is urged toward an upstream valve seat (11). The valve body (30) includes a head portion (31) that tapers toward the downstream side, a main body portion (32) including an opening (324), and a downstream-tapered flow-straightening portion (333).SELECTED DRAWING: Figure 4

Description

[Technical Field]

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

[0002] A known check valve uses a biasing member such as a compression spring to bias the valve disc toward the valve seat, and when fluid flow is stopped, the spring force presses the valve disc against the valve seat to prevent backflow. In this type of check valve, the spring biases the valve disc toward the valve seat, and to open the valve, the spring must be compressed to move the valve disc. However, when a fluid flows through a pipe, pressure loss occurs due to pipe friction with the pipe wall or turbulence caused by objects placed in the flow.

[0003] Various attempts have been made to reduce this pressure loss. For example, in Patent Document 1, a spacer is provided on the secondary side of a valve disc support member that is fixedly disposed within a casing to hold the valve disc. This spacer makes the flow around the support member and spacer extremely smooth, preventing separation and reducing pressure loss.

[0004] Furthermore, for example, Patent Document 2 discloses a control valve in which the valve body portion is conical. In this case, the valve body itself is conical, and this conical portion comes into contact with the seat portion to provide sealing.

[0005] Furthermore, for example, Patent Document 3 shows an underwater check valve in which the secondary side of the valve seat fixed inside the valve casing is conical, and the ball valve body and valve seat become one unit to form a streamlined shape when fluid flows through it. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-250349 [Patent Document 2] Japanese Patent Application Laid-Open No. 2015-021609 [Patent Document 3] Japanese Utility Model Application Publication No. 61-202763 Summary of the Invention [Problem to be solved by the invention]

[0007] In recent years, technologies that use gaseous or liquid hydrogen, such as hydrogen stations for automobile fuel cells, have been studied and are becoming more widespread, and check valves are also used in these devices that use hydrogen. In particular, in cases where hydrogen is flowing through a check valve at high pressure, turbulence that occurs on the secondary side of the check valve can have a significant impact on the check valve itself and various devices located downstream of the check valve.

[0008] An object of one aspect of the present invention is to provide a check valve that suppresses the generation of turbulent fluid flow. [Means for solving the problem]

[0009] In order to solve the above-mentioned problems, one aspect of the present invention provides a check valve comprising: a first pipe section through which a fluid flows; a valve seat located at the edge of an opening at the downstream end of the first pipe section; a second pipe section having an inner diameter larger than that of the first pipe section and connected to the downstream side of the first pipe section; a valve disc housed in the second pipe section and movable axially within the second pipe section; and a biasing member housed in the second pipe section and biasing the valve disc toward the first pipe section to seat it on the valve seat, wherein the valve disc has a head section that seats on the first valve seat, a communicating section that includes an opening located downstream of the head section and that connects the upstream side and downstream side of the second pipe section along the axial direction, and a flow straightening section that is located in the communicating section downstream of the head section, and both the head section and the flow straightening section have shapes in which the diameter of a cross section perpendicular to the axial direction decreases toward the downstream side. [Effects of the Invention]

[0010] According to one aspect of the present invention, a check valve that suppresses the generation of turbulent fluid flow can be realized. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a front view of a check valve according to a first embodiment of the present invention. [Figure 2] 1 is a plan view of a check valve according to a first embodiment of the present invention. [Figure 3] 1 is a right side view of a check valve according to a first embodiment of the present invention. [Figure 4] 2 is a cross-sectional view of the check valve of FIG. 1 taken along line AA in FIG. 1. [Figure 5] FIG. 1 is a perspective view showing a valve body according to a first embodiment of the present invention. [Figure 6] 1 is a view showing a cross section including the axis of a valve body according to a first embodiment of the present invention. [Figure 7] FIG. 2 is a left side view of the valve body according to the first embodiment of the present invention. [Figure 8] FIG. 2 is a right side view of the valve body according to the first embodiment of the present invention. [Figure 9] 3 is a diagram showing the position of the valve element when the check valve according to the first embodiment of the present invention is open. FIG. [Figure 10] FIG. 10 is a perspective view showing a valve body according to a second embodiment of the present invention. [Figure 11] FIG. 10 is a view showing a cross section including the axis of a valve body according to a second embodiment of the present invention. [Figure 12] 12 is an enlarged view of part B in FIG. 11. FIG. [Figure 13] 10A and 10B are diagrams illustrating a state in which the head of the valve disc contacts the valve seat when the valve disc is seated according to the second embodiment of the present invention. [Figure 14] FIG. 10 is a cross-sectional view including the axis of a check valve according to a third embodiment of the present invention. [Figure 15] FIG. 10 is a diagram showing a cross section including the axis of a protrusion according to a third embodiment of the present invention. [Figure 16] FIG. 10 is a diagram showing the axial position of a protrusion in a valve closed state according to a third embodiment of the present invention. [Figure 17] FIG. 10 is a diagram showing the axial position of the protrusion when the valve of the third embodiment of the present invention is slightly open. [Figure 18] FIG. 10 is a diagram showing the axial position of a protrusion when the valve of the third embodiment of the present invention is fully open. [Figure 19] 1 is a diagram showing the flow of fluid near the valve body of a check valve 1 according to an embodiment of the present invention. [Figure 20] FIG. 10 is a diagram showing the flow of fluid near the valve body of a check valve for comparison. DETAILED DESCRIPTION OF THE INVENTION

[0012] [Embodiment 1] An embodiment of the present invention will be described in detail below. Fig. 1 shows a front view of a check valve according to embodiment 1 of the present invention, Fig. 2 shows a plan view, and Fig. 3 shows a right side view. The check valve 1 has a first pipe section 10 and a second pipe section 20. The first pipe section 10 and the second pipe section 20 are made of a material that has sufficient corrosion resistance and strength under conditions such as the type and pressure of the fluid used; for example, in the case of liquefied hydrogen or hydrogen gas, both are made of stainless steel.

[0013] The first pipe section 10 is a pipe section through which a fluid flows. The second pipe section 20 is also a pipe section through which a fluid flows, has an inner diameter larger than that of the first pipe section 10, and is connected to the downstream side of the first pipe section 10. The first pipe section 10 and the second pipe section 20 are connected in a straight pipe shape, for example, with a packing interposed between them, by threading a first threaded section formed on the outer circumferential surface of the first pipe section 10 and a second threaded section formed at the upstream end of the inner circumferential surface of the second pipe section 20. A valve body 30 is housed inside the second pipe section 20.

[0014] In the following description, the central axis S of the check valve 1 will also be referred to simply as the "axis." The first pipe section 10 side of the check valve 1 is the upstream side in the direction of fluid flow, and the second pipe section 20 side of the check valve 1 is the downstream side in the direction of fluid flow. In the following description, "upstream" and "downstream" may be used to express positions in the axial direction.

[0015] FIG. 4 shows a cross section of the check valve 1 of FIG. 1 taken along line AA in FIG. 1. A cylindrical space is formed inside the first pipe section 10. The pipe wall on the downstream side of the first pipe section 10 is thicker than that on the upstream side. The first pipe section 10 has a valve seat 11 at the opening edge of its downstream end. The valve seat 11 covers the entire periphery of the opening edge of the downstream end of the first pipe section 10, and is located opposite the peripheral edge at the upstream end of the head 31 of the valve body 30, which will be described later.

[0016] The valve element 30 is housed within the second pipe section 20 so as to be movable within the second pipe section 20 in the axial direction of the second pipe section 20. A coil spring 40 is also disposed within the second pipe section 20 to press the valve element 30 toward the valve seat 11. The downstream end of the coil spring 40 is fitted into the downstream end of the second pipe section 20, and the upstream end of the coil spring 40 abuts against the valve element 30, urging the valve element 30 upstream. The coil spring 40 corresponds to a biasing member that urges the valve element 30 toward the first pipe section 10 to seat it on the valve seat 11.

[0017] FIG. 5 shows a perspective view of the valve disc 30, FIG. 6 shows a cross section of the valve disc 30 including the axis S, FIG. 7 shows a left side view of the valve disc 30, and FIG. 8 shows a right side view of the valve disc 30. The valve disc 30 is an integrally molded resin product having a head 31 and a body 32 (communicating portion). The material of the valve disc 30 may be any material that can exhibit sufficient sealing properties, and is determined appropriately depending on the application of the check valve 1. In this embodiment, the valve disc 30 is an integrally molded product made of a fluororesin (polytetrafluoroethylene (PTFE)) composition containing, for example, carbon fiber as a filler.

[0018] The head 31 is the upstream portion of the valve body 30. The head 31 has a shape in which the diameter of a cross section perpendicular to the axial direction decreases toward the downstream side. More specifically, the head 31 has a tapered outer shape in which the diameter gradually decreases from the upstream side toward the downstream side. In this way, the head 31 has a substantially truncated cone shape with the upstream side as the bottom. The outer diameter at the upstream end of the head is equal to, and slightly larger than, the outer diameter of the valve seat 11.

[0019] The head 31 has, at its upstream end, a peripheral edge 311, a first recess 312, a second recess 313, and a third recess 314, from the outside when viewed along the axial direction. The peripheral edge 311 is an annular portion when viewed along the axial direction, and is a flat plane portion that is flat in a direction perpendicular to the axis S. In this way, the peripheral edge 311 is configured to come into contact with the valve seat 11 over the entire circumference when the valve disc 30 advances toward the valve seat 11. In this way, the valve disc 30 has the head 31 that seats on the valve seat 11.

[0020] The first recess 312 is a portion recessed downstream from the inner peripheral edge of the peripheral edge 311, and forms an annular recess inside the peripheral edge 311. The second recess 313 is a portion recessed further downstream from the inner peripheral edge of the first recess 312, and forms a circular recess inside the first recess 312. The third recess 314 is a portion recessed downstream from the center of the bottom surface of the second recess 313, and forms a cylindrical recess in the center of the bottom surface of the second recess 313.

[0021] The shape of the inner circumferential side of the peripheral edge portion 311 in the head portion 31 does not have to be the shape having the first recess 312, the second recess 313, and the third recess 314 as in this embodiment. The shape of the inner circumferential side of the peripheral edge portion 311 may be, for example, flush with the peripheral edge portion 311, or may be recessed further than the peripheral edge portion 311. On the other hand, the sealing surface needs to be a highly accurate flat surface. Therefore, to eliminate the need for highly accurate machining over a wide area, it is preferable that the inner circumferential side of the peripheral edge portion 311 be recessed further than the peripheral edge portion 311.

[0022] The body 32 is located downstream of the head 31 and is the downstream portion of the valve body 30, and has an inner diameter larger than the maximum diameter portion (peripheral portion 311) of the head 31. The body 32 is a cylindrical portion whose outer peripheral wall can slide along the inner peripheral wall of the second pipe portion 20.

[0023] The body portion 32 has a cylindrical portion 321 that connects the upstream side and downstream side of the second pipe portion 20, and a flow rectifying portion 333.

[0024] Furthermore, the body 32 has, at the upstream end of the cylindrical portion 321, a center portion 322 that is substantially circular when viewed along the axial direction, and connecting portions 323 that connect the cylindrical portion 321 and the center portion 322 at three locations in the circumferential direction. The connecting portions 323 are arranged at equal intervals in the circumferential direction of the cylindrical portion 321. The center portion 322 is also connected to the head portion 31 on the upstream side and to the flow rectifying portion 333 on the downstream side. In this way, the valve body 30 has the flow rectifying portion 333 arranged in the body 32 at a position downstream of the head portion 31.

[0025] Furthermore, the body 32 has three openings 324 surrounded by the cylindrical portion 321, the central portion 322, and the connecting portion 323. The openings 324 are located at the upstream end of the body 32 in the axial direction, open along the axial direction, and communicate between the space upstream of the body 32 in the second tubular portion 20 and the space inside the cylindrical portion 321. Here, "opening along the axial direction" means that the openings 324 are formed by openings surrounded by a peripheral wall surface provided on the upstream end face of the body 32 and approximately parallel to the axial direction. In other words, the openings 324 communicate between the space upstream of the body 32 in the second tubular portion 20 and the space downstream of the body 32 via the internal space of the cylindrical portion 321. In this way, the body 32 has openings 324 that open in the axial direction, communicate between the upstream side and downstream side of the second tubular portion 20, and are located downstream of the head 31.

[0026] The opening shape of the opening 324 is a track-like shape curved in the longitudinal direction into an arc, and the end shape is a substantially semicircular shape with a diameter equal to the width of the opening 324. In this way, the opening shape of the opening 324 is formed by a continuous curve. The opening 324 is provided so that its outer diameter side is located outer than the maximum diameter portion (peripheral edge portion 311) of the head 31, and its inner diameter side is located in a region of the head 31 where the diameter is smaller, preferably near the center portion 322. In this way, the opening 324 opens in the radial direction of the valve disc 30 from a position outer than the head 31 when viewed axially from the upstream side to a position overlapping with the circumferential surface of the portion of the head 31 where the diameter is smaller when viewed axially from the downstream side.

[0027] Here, "the peripheral surface of the head 31 at a portion where the diameter is smaller when the valve element 30 is viewed axially from the downstream side" refers to a portion of the side peripheral surface of the head 31 where the diameter is smaller than the maximum diameter portion. Any portion of such a side peripheral surface satisfies the above-described condition for the opening of the opening 324 as long as the opening 324 is positioned so that the inner diameter side of the opening 324 overlaps the portion. In this embodiment, the inner diameter side of the opening 324 is formed as close to the center 322 as possible, and this position is set as far toward the inner diameter as possible within a range where the strength of the connection portion between the head 31 and the body 32 is not insufficient. Furthermore, this position is also determined so as to satisfy a predetermined relationship between the first flow path area A1 and the second flow path area A2, which will be described later.

[0028] Furthermore, the body portion 32 has three ribs 325 that protrude from the inner peripheral wall surface of the cylindrical portion 321 along the axial direction downstream from the connecting portion 323. The ribs 325 extend in the axial direction from the upstream end of the cylindrical portion 321 to near the center. The cross section of the ribs 325 that is perpendicular to the axial direction has a substantially trapezoidal shape.

[0029] As described above, the downstream end of the coil spring 40 is fixed to the downstream end of the second pipe section 20. Its upstream portion is inserted into the cylindrical section 321 from the downstream side and guided axially from the outer periphery by the tops of the ribs 325. The upstream end of the coil spring 40 abuts against the center section 322 while being entirely contracted in the axial direction. In this manner, the coil spring 40 abuts against the center section 322 at its upstream end while its downstream end is fixed in the axial direction, thereby biasing the valve disc 30 toward the upstream side. The downstream side of the coil spring 40 is held by the cylindrical section 321, and the upstream side is held by the ribs 325. Therefore, the centers of both ends of the coil spring 40 are aligned with the radial center of the body section 32, making it less likely to shift radially due to spring deflection or the like. Therefore, the peripheral edge 311 of the head section 31 abuts against the valve seat 11 with precision, further improving sealing performance.

[0030] As described above, in the check valve 1, the valve element 30 is composed of a head 31 and a body 32, and the head 31 has a shape that tapers in diameter from the valve seat 11 toward the body 32. The second tubular section 20 forms a valve chamber that houses the valve element, and the body 32 has a cylindrical shape with approximately the same inner diameter as the valve chamber. In addition, an opening 324 is provided on the upstream end surface of the body 32, which forms the boundary between the head 31 of the valve element 30 and the valve element 30, and which connects the head 31 side with the space inside the body 32 in the axial direction. Therefore, when the valve is open, a flow path is formed in the check valve 1 for fluid to pass through the body 32 from the outer periphery of the head 31 via the opening 324. In this way, the check valve 1 is configured so that, from the valve seat 11 in the axial direction to the upstream end of the body 32, the fluid flows through the space formed between the inner surface of the valve chamber and the outer surface of the head 31 (the space outside the valve body 30), and downstream of the upstream end of the body 32, the fluid flows inside the body 32 of the valve body 30 (the space inside the valve body 30).

[0031] Furthermore, in the check valve 1, the first flow path area A1 is designed to be substantially the same size as the second flow path area A2. The first flow path area A1 and the second flow path area A2 are both the areas of the flow paths through which a fluid can flow in a specific cross section perpendicular to the axial direction.

[0032] The first flow path area A1 is the difference between the flow path area of ​​the second pipe section 20 in a cross section perpendicular to the axial direction and the projected area of ​​the head section 31 when viewed in the axial direction from the upstream side. If the outer diameter of the cylindrical section 321 in the valve body 30 is substantially the same as the inner diameter of the second pipe section 20, the first flow path area A1 is the area of ​​the annular region formed between the periphery of the cylindrical section 321 and the outer edge of the peripheral section 311 in FIG. 7, for example.

[0033] The second flow path area A2 is the opening area of ​​the opening 324 in a cross section perpendicular to the axial direction. If the opening area of ​​one opening 324 is S1, the second flow path area A2 is expressed as 3 × S1. The second flow path area A2 is the sum of the opening areas of the three openings 324 in FIG. 8, for example.

[0034] If the difference between the first flow path area A1 and the second flow path area A2 is too large, the Cv value of the check valve 1 will be small, resulting in, for example, increased pressure loss due to fluid flow. The Cv value is an inherent coefficient that indicates the ease of fluid flow, and in this embodiment represents the capacity of the check valve 1. The difference between the first flow path area A1 and the second flow path area A2 may be any value that can achieve a Cv value that suits the application of the check valve 1 and the performance required of the check valve 1. From the perspective of achieving a Cv value equivalent to the theoretical value, the first flow path area A1 is 0.9 to 1.1 times the second flow path area A2.

[0035] Formulas for calculating the Cv value according to the type of fluid (liquid, gas, etc.) are widely known, and the theoretical value of the Cv value of the check valve 1 can be found based on such well-known formulas. In addition, the Cv value of the check valve 1 can be measured based on the method specified in the Japanese Industrial Standards (JIS) (e.g., B2005-2-3).

[0036] In this way, the check valve 1 has the characteristic that the first flow path area A1, which is the cross-sectional area of ​​the space between the maximum diameter portion of the head 31 of the valve body 30 and the inner wall surface of the second pipe section 20, and the second flow path area A2, which is the total opening area of ​​the openings 324 at the upstream end face portion of the body section 32, are approximately equal.

[0037] The Cv value of a given flow path is affected by the cross-sectional area of ​​the narrowest part of the flow path. In the structure of the check valve 1 of this embodiment, either the first flow path area A1 or the second flow path area A2 is the narrowest point of the flow path. To achieve a high Cv value, the narrowest of the first flow path area A1 and the second flow path area A2 should be made as large as possible. Specifically, this can be achieved by increasing the outer diameter of the second pipe section 20. However, when the check valve 1 is used in an automobile, ship, or aircraft, for example, and installation space is limited, it is desirable to keep the overall diameter of the check valve 1 as small as possible. If the diameter of the second pipe section 20 is small, the first flow path area A1, which only has space on the outer diameter side of the head 31 of the valve body 30, must also be small. Furthermore, if the opening 324 is made too large in an attempt to increase the second flow path area A2, the strength of the connecting section 323 and other components may be insufficient.

[0038] Therefore, in the check valve 1, the opening 324 is formed so as to open from a position radially outward of the head 31 to a position overlapping with the circumferential surface of the portion of the head 31 where the diameter becomes smaller in the valve body 30. In this way, in this embodiment, the opening 324 can be opened to its maximum extent within the limited range of the overall outer diameter. Therefore, the check valve 1 can achieve a high Cv value.

[0039] Furthermore, in the check valve 1, the first flow path area A1 is set to 0.9 to 1.1 times the second flow path area A2. In this way, the check valve 1 ensures that the first flow path area A1 and the second flow path area A2 are as large as possible within the limited range of the overall outer diameter, and this configuration also contributes to achieving a high Cv value.

[0040] The flow rectifying section 333 is located at the upstream end within the body section 32. Specifically, the flow rectifying section 333 protrudes from the upper end of the cylindrical section 321 (the side where the central section 322 and the connecting section 323 are provided) into the interior of the cylindrical section 321 toward the downstream side. The flow rectifying section 333 has a shape in which the diameter of a cross section perpendicular to the axial direction decreases toward the downstream side. In the example shown in FIG. 6, the flow rectifying section 333 has a tapered outer shape in which the diameter of a cross section perpendicular to the axial direction gradually decreases from the upstream side toward the downstream side. If the flow rectifying section 333 were represented three-dimensionally, it would have a conical shape with a diameter that decreases toward the downstream side.

[0041] The tapered surface of the flow rectifying portion 333 continues from a peripheral wall surface that is substantially parallel to the axial direction and defines the opening 324, and that is located at the boundary with the center portion 322. In other words, the diameter of the cross section of the upper end of the flow rectifying portion 333, i.e., the boundary portion with the center portion 322, is preferably equal to the diameter of the cross section of the center portion 322 that is perpendicular to the axial direction. This can contribute to the orderly flow of the fluid that flows in from the opening 324 downstream.

[0042] The flow rectifying portion 333 preferably has a central axis that is coaxial with the central axis (axis S) of the cylindrical portion 321 and has a shape that is rotationally symmetrical about the central axis. This makes it possible to equalize the pressure of the fluid that flows in from each of the openings 324 located around the flow rectifying portion 333. If the fluid pressure is not uniform, excessive pressure will be applied only to a portion of the tapered surface of the flow rectifying portion 333. This will cause rattles (vibrations) in the flow rectifying portion 333 and will also cause turbulence downstream of the flow rectifying portion 333. Furthermore, vibrations in the flow rectifying portion 333 will also cause vibrations in the body portion 32 (cylindrical portion 321).

[0043] Therefore, it is preferable that the central axis of the flow rectifying portion 333 is positioned coaxially with the central axis (axis S) of the cylindrical portion 321 and has a shape that is rotationally symmetrical with the central axis as the axis of rotation. This can suppress vibration of the flow rectifying portion 333 and contribute to suppressing turbulence.

[0044] The suitable length of the flow straightening portion 333 (the length (protruding length) from the center portion 322, which is the upper end portion of the cylindrical portion 321, toward the downstream side) is determined in relation to the other components of the valve body 30. That is, first, the taper angle of the tapered surface of the flow straightening portion 333 is an important factor. The taper angle of the tapered surface of the flow straightening portion 333 is defined as the angle that the tapered surface of the flow straightening portion 333 makes with respect to the axial direction in a cross section including the axis S, and is the angle shown as θ333 in FIG. 6. The taper angle θ333 can be appropriately determined from the viewpoint of suppressing pressure loss of the fluid. From the viewpoint of achieving this, it is preferable that the taper angle be approximately the same as the taper angle of the tapered surface of the head portion 31, which will be described later.

[0045] The taper angle of the tapered surface of the head 31 is defined as the angle that the outer peripheral surface of the head 31 makes with respect to the axial direction in a cross section including the axis S. The allowable outer diameter and axial length of the second pipe section 20 are regulated to some extent within the constraints of the overall size of the check valve 1. The valve element 30 is composed of the head 31 and the body 32. The axial length of the body 32 is affected by the required length of the coil spring 40 disposed therein, and the length of the coil spring 40 is determined according to the spring force (F = kx (k = spring constant, x = distance)) required to close the valve element 30. In the case of the check valve 1 of this embodiment, it is desirable that the force (fluid pressure) required to open the valve does not change significantly depending on the opening degree. Therefore, it is desirable that the spring force does not increase rapidly due to compression of the spring. For this reason, it is preferable that the length of the spring be as long as possible.

[0046] Furthermore, since increasing the guide distance on the inner peripheral wall of the second tubular section 20 stabilizes the operation of the valve element 30, it is preferable to make the axial length of the body section 32 as long as possible while still ensuring the compression amount of the coil spring 40. The axial length of the body section 32 is determined from the above-mentioned perspective, and the axial length of the head section 31 is also determined based on the relationship between this and the volume of the second tubular section 20. From this perspective, in this embodiment, the ratio of the length of the head section 31 to the length of the body section 32 in the axial length of the valve element 30 is set to approximately 1:4. The taper angle of the tapered surface of the head section 31 is set so as to maximize the first flow path area A1 and the second flow path area A2, which will be described later, based on the relationship between the inner diameter of the second tubular section 20 and the allowable axial length of the head section 31.

[0047] If the taper angle is too large, this is preferable from the viewpoint of downsizing the valve element 30 in the axial direction, but the flow perpendicular to the axial direction increases relative to the axial flow, which may make it difficult for the valve element 30 to open and increase fluid pressure loss. If the taper angle is too small, this is preferable from the viewpoint of making the valve element easy to open and suppressing fluid pressure loss, but the axial dimension of the valve element 30 becomes large. The taper angle can be appropriately determined from the viewpoints of downsizing, ease of opening the valve element, and suppression of fluid pressure loss. From the viewpoint of achieving these, the taper angle is preferably about 60°. Furthermore, it is preferable that the taper angle of the tapered surface of the flow rectification section 333 is also about the same.

[0048] The taper angle of the tapered surface of head portion 31, the protruding length of flow rectifying portion 333, and the taper angle of the tapered surface can be set as appropriate depending on the amount of fluid flowing through the device in which check valve 1 is installed, the pressure of the fluid, etc., and the above-mentioned numerical values ​​are merely examples. For example, the above-mentioned taper angle is not limited to 60° and may be a different angle, and the effects of the present invention can be sufficiently obtained even if the taper angle of head portion 31 and the taper angle of flow rectifying portion 333 are not necessarily the same but are different from each other, but in a preferred case, the range of change is approximately 60°±15°. Furthermore, the tapered surfaces of head portion 31 and flow rectifying portion 333 do not necessarily have to be tapered surfaces and may be curved surfaces.

[0049] Here, the protruding tip of the flow rectifying portion 333 forms a plane perpendicular to the central axis S. In other words, strictly speaking, the flow rectifying portion 333 can be said to be frustum-shaped ( FIG. 6 ). The fact that the shape of the flow rectifying portion 333 is frustum-shaped is preferable from the viewpoint of improving productivity (ease of molding, mold releasability, etc.) when forming the valve body 30 including such flow rectifying portion 333 as an integrally molded product. However, the shape is not limited to a frustum-shaped cone, and a cone-shaped cone may also be used. Furthermore, even if the shape is frustum-shaped, the tip may not be flat but may be approximately hemispherical with rounded corners. Furthermore, the shape does not have to be conical, and a triangular pyramid shape may also be used. In the case of a triangular pyramid shape, the three side surfaces may correspond to the positions of the three openings 324, respectively.

[0050] The check valve 1 opens and closes as follows: The valve element 30 is biased from the downstream side toward the upstream side by the coil spring 40. Therefore, as shown in Figure 4, the peripheral edge 311 is in close contact with the valve seat 11 over the entire periphery. In this way, when no fluid is flowing, the check valve 1 is closed.

[0051] FIG. 9 shows a schematic diagram of the check valve 1 when it is open. When a fluid is supplied to the first pipe section 10, the internal pressure of the first pipe section 10 increases. When the pressure of the fluid in the first pipe section 10 exceeds a certain pressure (cracking pressure), the fluid pressure overcomes the biasing force of the coil spring 40, and the valve element 30 moves downstream (to the right in the figure). As shown by the arrows in FIG. 9, the fluid passes through the space on the outer periphery of the head section 31 of the valve element 30, flows into the cylindrical section 321 through the opening 324 of the body section 32, and then passes through the cylindrical section 321 and flows out to the downstream side of the second pipe section 20.

[0052] 9, a portion of the fluid that has flowed into cylindrical portion 321 through opening 324 of body portion 32 moves toward central axis S as the flow moves downstream. The fluid flowing in this direction is changed in direction by the tapered surface of flow rectification portion 333, and is rectified in a direction parallel or nearly parallel to central axis S. The flow rectification effect of flow rectification portion 333 will be described later in the examples.

[0053] It is preferable that the circumferential side surface of the flow rectifying portion 333 be a continuous tapered surface from the center portion 322 of the cylindrical portion 321 toward the protruding tip portion, as this allows for accurate flow rectification. However, the circumferential side surface of the flow rectifying portion 333 may not be a continuous tapered surface, for example, it may include a surface parallel to the axis S in part of the circumferential side surface. Furthermore, the flow rectifying portion 333 only needs to have a circumferential side surface (tapered surface), and a space may be provided inside the flow rectifying portion 333.

[0054] As described above, the check valve 1 of this embodiment includes the valve element 30 having the head 31, and the body 32 with the opening 324 provided downstream of the head 31. Therefore, when the valve is open, a fluid flow path is formed that passes from the outer periphery of the head 31 through the body 32 via the opening 324. In this way, the check valve 1 is configured to allow fluid to flow through the space inside the body 32 of the valve element 30. This space is cylindrical and does not substantially have any parts inside that would obstruct the flow of fluid. Therefore, when the check valve 1 is open, the fluid can flow smoothly from the first pipe section 10 to the second pipe section 20.

[0055] Furthermore, the check valve 1 has an opening 324 that opens in the axial direction on the upstream end face of the body 32. This allows the fluid to flow more linearly in the axial direction when the valve is open, allowing the check valve 1 to allow the fluid to flow smoothly when the valve is open.

[0056] Furthermore, in the check valve 1, the head 31 of the valve element 30 has a shape that tapers in diameter from the valve seat 11 toward the body 32. Therefore, without increasing the outer diameter of the valve element 30, the cross-sectional area of ​​the flow path in the valve chamber (the cross-sectional area of ​​the space between the inner circumferential surface of the second pipe section 20 and the valve element 30) can be made sufficiently large.

[0057] The body 32 has a cylindrical portion 321. The cylindrical portion 321 has a peripheral wall that is slidable along the entire circumference against the inner peripheral wall of the second tube portion 20. This is advantageous from the viewpoint of preventing the head 31, which receives fluid pressure when the valve is opened, from shaking and allowing the valve element 30 to move smoothly along the axial direction when the valve is opened or closed.

[0058] Furthermore, body portion 32 has, on its upstream end surface, a flow rectifying portion 333 that protrudes downstream. Flow rectifying portion 333 has a shape in which the diameter of a cross section perpendicular to the axial direction decreases toward the downstream side. Therefore, of the fluid that has flowed into cylindrical portion 321 through opening 324, the flow of the fluid that flows in a direction approaching central axis S as it moves downstream can be rectified by the peripheral side surface (tapered surface) of flow rectifying portion 333 in a direction parallel or nearly parallel to central axis S.

[0059] In a comparative example in which the flow rectifying section 333 is not provided, the fluid that flows into the cylindrical section (corresponding to the cylindrical section 321 in this embodiment) through the opening (corresponding to the opening 324 in this embodiment) swirls in a direction approaching the central axis S, causing the valve body 30 to vibrate. This is because the portion that has been flowing linearly along the head 31 suddenly loses its surface along the flow. In contrast, the flow rectifying section 333 in this embodiment allows the fluid that has passed through the opening 324 to continue flowing linearly along the flow rectifying section 333. Therefore, the fluid that flows into the cylindrical section 321 is rectified in a direction parallel or nearly parallel to the central axis S, which results in suppressing the generation of vortexes in the cylindrical section 321 and suppressing vibration of the valve body 30.

[0060] Furthermore, since the rectifying section 333 is configured as part of the valve body 30, the fluid that flows into the cylindrical section 321 can be rectified by the rectifying section 333 even when the valve body 30 is at an intermediate opening.

[0061] Furthermore, by providing the rectifying section 333 on the valve element 30, it is possible to suppress axial vibration of the valve element 30 caused by the above-mentioned vortex when the valve is open, and to fix the axial position of the valve element 30 when the valve is open to a position according to the opening degree. In particular, it is possible to suppress such vibration of the valve element 30 even at intermediate opening degrees.

[0062] Furthermore, without the flow rectifier 333, the fluid's flow velocity increases until it passes through the opening 324. The fluid then passes through the opening 324 and flows into the cylindrical portion 321, which does not have the flow rectifier 333. At this time, the fluid's flow path expands, causing the fluid to rapidly decelerate. Such a rapid deceleration in the fluid's flow velocity can cause cavitation (bumping). In particular, when the fluid is liquefied hydrogen, its boiling point is extremely low at −253°C, making it prone to vaporization. Therefore, fluctuations in flow velocity and pressure can easily cause cavitation. However, the presence of the flow rectifier 333 in this embodiment makes it difficult for a rapid deceleration in the flow velocity to occur when the fluid flows into the cylindrical portion 321, thereby more easily preventing cavitation.

[0063] Furthermore, the body portion 32 has a rib 325 extending downstream from the connecting portion 323. This is preferable from the viewpoint of reinforcing the connecting portion 323 and the upstream portion of the cylindrical portion 321. The rib 325 also restricts the movement of the coil spring 40 toward the outer periphery by the amount of its protrusion from the inner circumferential surface of the cylindrical portion 321. Therefore, having the rib 325 on the body portion 32 is preferable from the viewpoint of maintaining the position of the coil spring 40 within the body portion 32 closer to the center in the radial direction, allowing the coil spring 40 to accurately exert the desired biasing force on the valve element 30, and achieving the desired responsiveness of the check valve 1.

[0064] Furthermore, in the check valve 1, the opening 324 is configured to open to its substantially maximum extent in the radial direction of the valve element 30. Therefore, in the check valve 1, it is possible to sufficiently increase the cross-sectional area of ​​the flow path defined by the opening 324. Therefore, the check valve 1 can achieve a high Cv value.

[0065] Furthermore, in the check valve 1, the first flow path area A1 and the second flow path area A2 are approximately the same. Therefore, the Cv value achieved by the step area of ​​the flow path in the axial direction at the valve seat, which is the first flow path area A1, is substantially maintained even at the opening 324, where the flow path is subsequently narrowed and which is the second flow path area A2. Therefore, the check valve 1 can substantially achieve the target Cv value ensured by the flow path in the axial direction at the valve seat.

[0066] The magnitude of the Cv value is determined by the cross-sectional area of ​​the contraction portion of the valve's flow path. In the check valve 1, the cross-sectional areas of the cross sections perpendicular to the axial direction of each of the following flow paths affect the Cv value: the axial fluid flow path near the valve seat (the portion with the first flow path area A1), the flow path formed by the opening 324 downstream of that (the portion with the second flow path area A2), and the flow path located between them along the head 31 toward the body 32. In particular, the portion with the first flow path area A1 and the portion with the second flow path area A2 are contraction portions where the cross-sectional area of ​​the fluid flow path is reduced. Therefore, making the cross-sectional areas of these portions equal is advantageous for maximizing these cross-sectional areas and is effective in efficiently ensuring the Cv value of the check valve 1.

[0067] In the check valve 1, the inner diameter of the second pipe section 20 can be determined from the perspective of ensuring a first flow path area A1 that achieves a target Cv value while ensuring a minimum outer diameter of the valve seat 11. In the check valve 1, the flow path area gradually increases in the axial direction between the portion that forms the first flow path area A1 and the portion that forms the second flow path area A2, but the flow path narrows again in the portion that forms the second flow path area A2. In the check valve 1, by making the second flow path area A2 (the sum of the opening areas of the openings 324) equal to the first flow path area A1, it is possible to obtain the target Cv value ensured by the first flow path area A1.

[0068] In the check valve 1, the inner diameter of the second tubular section 20 is determined by determining the first flow path area A1 according to the target Cv value as described above, and the outer diameter of the body 32, which is approximately equal to the inner diameter, is also determined. If the body 32 is made thicker to increase the second flow path area A2, the radially outer opening of the opening 324 can be made larger, making it easier to ensure a large Cv value. However, this results in a larger check valve 1. Furthermore, if the flow velocity of the fluid in the second tubular section 20 is increased by making the body 32 thicker, the fluid pressure may decrease, making it difficult for the valve element 30 to open. Therefore, it is advantageous to set the outer diameter of the body 32 to be approximately the same as the inner diameter of the second tubular section 20, which is determined based on the first flow path area A1, from the perspectives of miniaturization and increasing the sensitivity (responsiveness to fluid pressure) of the check valve 1.

[0069] When the outer diameter of the body 32 is determined in this way, a flow path that is sufficiently wide in the radial direction, particularly toward the center, is required to ensure a sufficient second flow path area A2. In the check valve 1, the head 31 has a shape in which the diameter of the cross section perpendicular to the axial direction gradually decreases toward the downstream side, making it possible to form an opening 324 that widens toward the center in the radial direction further downstream (at the upstream end of the body 32).

[0070] The relationship between the first flow path area A1 and the second flow path area A2 is preferably such that the first flow path area A1 is within a range of 0.5 to 2.0 of the second flow path area A2. When there are two elements that determine the Cv value in one flow path, the Cv value of that flow path is obtained as the combined effect (composite Cv value) of the Cv values ​​of the two elements. In this case, if the Cv value of one element is more than twice the Cv value of the other element, the combined Cv value tends to remain approximately constant around the lower Cv value. In other words, even if one Cv value is designed to be higher so that the difference in Cv values ​​becomes even greater, the effect of increasing the combined Cv value is almost not achieved. Since the Cv value is approximately proportional to the flow path area, if the flow path area of ​​one of the two elements that reduce the flow path area is not more than twice the flow path area of ​​the other, there is no need to excessively increase the pipe diameter of the second pipe section 20. When there are two elements, the combined Cv value is maximized when both elements have the same Cv value. Therefore, it is most preferable that the first flow path area A1 and the second flow path area A2 are the same, but it is preferable that the first flow path area A1 is in the range of 0.9 to 1.1 relative to the second flow path area A2, since this can keep the overall decrease in Cv value to about 5% or less.

[0071] As described above, the check valve 1 allows fluid to flow easily when the valve is open, and is capable of achieving a high Cv value. Furthermore, by including the flow rectifying section 333, the check valve 1 can suppress the occurrence of turbulent flow, such as the aforementioned excessive flow, when the valve is open, and can substantially prevent axial vibration of the valve element 30 when the valve is open. Furthermore, the check valve 1 is advantageous for miniaturization. Therefore, the check valve 1 is suitable as a check valve that is lightweight, compact, and capable of allowing fluid to flow at a high flow rate. The check valve 1 can be used in applications requiring such characteristics, and is suitable, for example, as a check valve installed on an aircraft.

[0072] Other embodiments of the present invention will be described below. For convenience of explanation, in the following embodiments, components having the same functions as those described in the previous embodiments will be denoted by the same reference numerals, and the description thereof will not be repeated.

[0073] [Embodiment 2] The check valve of this embodiment has the same configuration as the check valve 1 of the above-described embodiment 1, except that it further has a protrusion portion that is provided around the periphery of the head of the valve body 30 and abuts against the valve seat when the head is seated.

[0074] A perspective view of the valve disc in this embodiment is shown in Fig. 10, and a cross section of the valve disc including its axis S is shown in Fig. 11. An enlarged view of part B in Fig. 11 is shown in Fig. 12. The check valve of this embodiment has a valve disc 230. The valve disc 230 is configured similarly to the valve disc 30 of the first embodiment described above, except that it has a head part 231. The head part 231 is configured similarly to the head part 31 of the first embodiment described above, except that it further has a ridge part 315.

[0075] The protrusion 315 is formed around the entire circumference at the radial center of the peripheral edge 311. The protrusion 315 has a substantially semicircular cross-sectional shape. The curvature R of the cross-sectional shape of the protrusion 315 is set according to the surface pressure required when the valve body 230 is seated.

[0076] 13 schematically shows the state in which the head 231 contacts the valve seat 11 when the valve disc 230 of this embodiment is seated. When the valve disc 230 is seated on the valve seat 11, the protrusion 315 contacts the valve seat 11 over the entire periphery. Furthermore, since the valve disc 230 is biased upstream by the coil spring 40, a surface pressure corresponding to the biasing force of the coil spring 40 is generated at the contact portion of the protrusion 315 with the valve seat 11.

[0077] Therefore, in this embodiment, the seating of the valve disc 230 achieves a seal closer to a linear one, and the surface pressure of the valve disc 230 against the valve seat 11 is further increased. In the case of embodiment 1, the peripheral edge 331 of the valve disc 30 is flat, but repeated contact with the valve seat 11 may cause a dent in the seal portion. If the dent can contact the valve seat 11, leakage will not occur. However, when handling an ultra-low temperature fluid such as liquefied hydrogen, thermal contraction due to low temperature may cause differential contraction between the valve disc 30 and the valve seat 11, resulting in misalignment of the contact positions, which may result in leakage. In contrast, according to this embodiment, even when the fluid temperature is low and the valve disc 230 thermally contracts, the approximately semicircular cross-section of the protrusion 315 is maintained and a portion of it contacts the valve seat 11, thereby forming the linear seal as described above. Therefore, the check valve according to this embodiment achieves the same effects as embodiment 1 and is more suitable as a check valve for extremely low temperature fluids such as liquid hydrogen than the check valve 1 of embodiment 1.

[0078] [Embodiment 3] The check valve of this embodiment has the same configuration as the check valve 1 of the first embodiment described above, except that it further includes a protruding portion 50. The protruding portion 50 is preferably made of a material with sufficient strength, such as stainless steel. If the protruding portion 50 is made of a material with sufficient strength, it is possible to prevent the peripheral portion 311 of the head 31 of the valve element 30 from shrinking toward the inner diameter, even when an ultra-low temperature fluid such as liquefied hydrogen is used as the fluid, thereby maintaining the contact position with the valve seat 11 and maintaining sealing performance.

[0079] The check valve of this embodiment is shown in Figure 14. The check valve 3 further has a protrusion 50 attached to the upstream end of the head 31. Otherwise, the check valve 3 is configured in the same manner as the check valve 1 of the first embodiment described above.

[0080] 15 shows a cross section of the protrusion 50 including the axis S. The protrusion 50 has a tip end 51 on the upstream side and a base end 52 on the downstream side.

[0081] The tip portion 51 has a circular shape when viewed along the axial direction, and has a generally trapezoidal shape with a diameter that gradually decreases toward the upstream side when viewed in a direction perpendicular to the axis S. The diameter of the tip portion 51 at the downstream end is approximately equal to the diameter of the first recessed portion 312, but slightly smaller than the diameter of the first recessed portion 312. The taper angle of the peripheral surface of the tip portion 51 is approximately several degrees. How to determine this taper angle will be described later.

[0082] The tip portion 51 has a fourth recess 511 on its upstream end surface. The fourth recess 511 is a recess that is circular when viewed along the axial direction and has a diameter smaller than the diameter of the tip portion 51 on the upstream end surface. The fourth recess 511 also has a depth approximately the same as that of the first recess 312 of the head portion 31.

[0083] The base end 52 is a cylindrical portion that continues downstream from the tip end 51. The diameter of the base end 52 is approximately equal to the diameter of the second recess 313, but is slightly smaller than the diameter of the second recess 313. The thickness of the base end 52 is approximately equal to the depth of the second recess 313.

[0084] The protruding portion 50 has a circular through-hole 512 in the center when viewed in the axial direction. The through-hole 512 has a diameter approximately the same as that of the third recess 314 of the head portion 31.

[0085] The protrusion 50 is fixed to the upstream end of the head 31 by fitting the base end 52 into the second recess 313 and using a fixing member such as a pin or screw that is inserted into the through hole 512 from the upstream side and reaches the third recess 314.

[0086] 16 shows the axial position of the protrusion 50 of the check valve 3 when the valve is closed. Because the protrusion 50 is attached to the upstream end of the head 31, when the head 31 is seated on the valve seat 11, the tip 51 reaches a position further upstream than the valve seat 11. Because the peripheral wall of the tip 51 has a tapered surface as described above, a gap is formed between the protrusion 50 and the inner peripheral wall surface of the first pipe section 10. In this way, the check valve 3 has the protrusion 50 that is disposed at the upstream end of the head 31 and that enters the first pipe section 10 when the valve disc of the head 31 is seated. The protrusion 50 enters the first pipe section 10 so as to form a gap between the protrusion 50 and the inner peripheral wall surface of the first pipe section 10.

[0087] 17 shows the axial position of the protrusion 50 when the check valve 3 is slightly open. When fluid is supplied to the first pipe section 10 and the valve element 30 is slightly separated from the valve seat 11, the fluid flows through the gap between the inner circumferential wall surface of the first pipe section 10 and the tapered surface of the tip section 51. During this time, the fluid is being supplied to the first pipe section 10, and the pressure of the fluid inside the first pipe section 10 rises in accordance with the amount of fluid being supplied.

[0088] On the other hand, since the valve element 30 is biased toward the upstream side by the coil spring 40, the axial position of the valve element 30 is determined by the extension force of the coil spring 40. Therefore, in the state shown in Fig. 17, the valve element 30 receives pressure from the fluid that moves it toward the downstream side by an amount corresponding to the thickness of the tip end 51.

[0089] Because there is a gap between the protrusion 50 and the inner peripheral wall surface of the first pipe section 10, the flow rate of the fluid is restricted to the amount that can pass through the gap from when the valve is closed to when it is slightly open. Even when the valve disc 30 is seated on the valve seat 11 (when the valve is closed), the protrusion 50 enters the first pipe section 10 just before the valve disc 30 is seated on the valve seat 11, so a gap is formed between the inner peripheral wall surface of the first pipe section 10 and the protrusion 50, and the flow rate of the fluid is restricted in the same way as when the valve is open.

[0090] 18 shows the axial position of the protrusion 50 when the check valve 3 is fully open. When the protrusion 50 is located downstream of the valve seat 11, the gap described above is eliminated, and fluid flows at the same flow rate as when the valve element 30 without the protrusion 50 is open or closed.

[0091] As described above, in the check valve 3, the head 31 of the valve element 30 facing the valve seat 11 is provided with a protrusion 50 having a diameter slightly smaller than the inner diameter of the first pipe section 10 and protruding into the first pipe section 10 when the valve element 30 is seated on the valve seat 11. By providing such a protrusion 50, when the valve element 30 is slightly open, the fluid flows through a narrow gap between the inner peripheral wall of the first pipe section 10 and the outer peripheral wall of the protrusion 50. Therefore, the flow rate of the fluid when the valve element 30 is slightly open is restricted. When the valve element 30 moves further in the opening direction (downstream) and the protrusion 50 leaves the first pipe section 10, the opening between the valve seat 11 and the head 31 of the valve element 30 suddenly becomes larger, and the flow rate of the fluid suddenly increases. In this way, in the check valve 3, the flow rate suddenly increases at a specific opening when the valve is open. Therefore, in addition to the effects of the check valve 1 of the first embodiment described above, the check valve 3 has excellent on-off switching performance, in which the flow rate increases suddenly when a predetermined opening is exceeded.

[0092] The degree of such switching performance is determined by the size of the gap between the protruding portion 50 and the inner circumferential wall surface of the first tubular portion 10; the smaller the gap, the more pronounced the on-off switching. In this embodiment, the circumferential surface of the tip portion 51 is tapered, and the size of the gap is determined by the taper angle. The larger the taper angle, the larger the gap. In this way, the taper angle of the tip portion 51 is determined according to the desired degree of on-off switching performance.

[0093] If the gap is too small, the protrusion 50 may come into contact with the valve seat 11 when the valve is closed, preventing it from entering the first pipe section 10. However, in this embodiment, the peripheral surface of the tip 51 is tapered. Therefore, the protrusion 50 can easily enter the first pipe section 10 when the valve is closed, and contact between the protrusion 50 and the valve seat 11 when the valve is closed is prevented while a small gap is maintained between the protrusion 50 and the inner peripheral wall surface of the first pipe section 10. Therefore, even if the valve element 30 further has the protrusion 50, the accuracy of opening and closing the valve element 30 is sufficiently maintained.

[0094] Furthermore, the protrusion 50 has a generally disk-shaped structure as described above. When the fluid is a low-temperature fluid such as liquid hydrogen, the valve element 30 may thermally shrink, which may affect the sealing performance of the valve element 30. The check valve 3 has a highly rigid protrusion 50 at the upstream end of the head 31 of the valve element 30, which is suitable from the perspective of suppressing radial deformation of the head 31 due to heat.

[0095] Other Embodiments The protruding portion 315 in the second embodiment may be further applied to the check valve 3 having the protrusion 50 in the third embodiment. Such a check valve achieves both the effects of the second embodiment and the effects of the third embodiment.

[0096] The body 32 does not have to be cylindrical. The body 32 may be a plate-like member having an opening 324, or may be a member that, in addition to the plate-like member, has a sliding portion that extends in the axial direction and slides against the inner circumferential surface of the second pipe portion 20. Note that it is preferable that the sliding portion be located in a radially symmetrical position (a position of rotational symmetry about the axis S in a cross section perpendicular to the axial direction) from the viewpoint of suppressing radial vibration when the valve body 30 is opened or closed.

[0097] The change in diameter of the head 31, in a cross section perpendicular to the axial direction, which decreases toward the downstream side, does not have to be a linear change but may be a curved change (for example, an acorn shape). Moreover, the change in diameter does not have to be continuous but may be an intermittent change (for example, a step-like change).

[0098] Similarly, the change in diameter of the flow straightening section 333, in which the diameter of the cross section perpendicular to the axial direction decreases toward the downstream side, does not have to be a linear change, as long as the flow straightening effect described above can be obtained. For example, the change in diameter in the flow straightening section 333 may be a curved change (e.g., an acorn shape). Furthermore, as long as the flow straightening effect described above can be obtained, the change in diameter does not have to be continuous, but may be an intermittent change (e.g., a step-like change). The degree of the flow straightening effect provided by the flow straightening section 333 can be set appropriately depending on the application of the check valve, as long as a practical effect can be obtained.

[0099] Instead of the protrusion 315 in the second embodiment, a protrusion may be formed that protrudes from the valve seat 11 around the entire periphery. In this way, at the sealing portion where the valve seat 11 and the head 31 contact each other, one side may be convex and the other side may be flat. Furthermore, these protrusions do not necessarily have to have a semicircular cross section, and may be V-shaped or the like.

[0100] In the third embodiment, the protruding portion 50 does not have to be a plate-shaped member. For example, the protruding portion may be a member that forms the above-described gap between itself and the inner peripheral wall surface of the first pipe portion 10 (for example, an annular member having the above-described tapered outer peripheral surface).

[0101] As described above, the present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention.

[0102] 〔summary〕 A first aspect of the present invention is a check valve (1, 3) having a first pipe section (10) through which a fluid flows, a valve seat (11) located at the edge of the opening at the downstream end of the first pipe section, a second pipe section (20) having an inner diameter larger than that of the first pipe section and connected to the downstream side of the first pipe section, a valve body (30, 230) housed in the second pipe section and movable within the second pipe section in the axial direction of the second pipe section, and a biasing member (coil spring 40) housed in the second pipe section and biasing the valve body toward the first pipe section to seat it on the valve seat, wherein the valve body has a head section (31) seated on the valve seat (11), a communication section (body section 32) including an opening section (324) located downstream of the head section and connecting the upstream side and downstream side of the second pipe section along the axial direction, and a flow straightening section (333) located downstream of the head section in the communication section, and both the head section and the flow straightening section have shapes in which the diameter of a cross section perpendicular to the axial direction decreases toward the downstream side. According to the first aspect, the flow straightening section can straighten the fluid flowing through the opening downstream, thereby reducing the generation of turbulence such as vortices in the fluid that has passed through the opening, and achieving a check valve with reduced vibration of the valve body.

[0103] A second aspect of the present invention may be configured such that, in the first aspect, the difference between the flow path area of ​​the second pipe section in a cross section perpendicular to the axial direction and the projected area of ​​the head section when viewed axially from the upstream side is defined as the first flow path area (A1), and the opening area of ​​the opening is defined as the second flow path area (A2), the first flow path area is 0.9 to 1.1 times the second flow path area. By setting the first flow path area to 0.9 to 1.1 times the second flow path area, the Cv value achieved by the step area of ​​the flow path in the axial direction at the valve seat, which is the first flow path area, is substantially maintained even at the opening, which is the second flow path area, where the flow path is subsequently narrowed. Thus, according to the second aspect, it is possible to substantially achieve the target Cv value ensured by the flow path in the axial direction at the valve seat.

[0104] A third aspect of the present invention may be configured as in the first aspect, where the communication portion is a cylindrical body portion slidable within the second pipe portion, the opening portion is located at the upstream end of the body portion, and the rectifying portion is located at the upstream end within the body portion. According to the third aspect, the rectifying portion can rectify the fluid flowing into the body portion from the upstream end within the body portion through the opening toward the downstream at the upstream end within the body portion. Furthermore, according to the second aspect, rectification by the rectifying portion prevents the head portion from shaking, which is subjected to fluid pressure when the valve is opened, and allows the valve element to move smoothly along the axial direction when the valve is opened or closed.

[0105] In a fourth aspect of the present invention, in the first or second aspect, the flow straightening portion may have a tapered outer shape whose diameter gradually decreases from the upstream side to the downstream side. According to the fourth aspect, of the fluid flowing through the opening, the flow of the fluid that flows in a direction approaching the central axis as it moves downstream can be changed by the tapered surface of the flow straightening portion, and the fluid can be straightened in a direction parallel or nearly parallel to the central axis S.

[0106] A fifth aspect of the present invention is any of the first to third aspects, wherein the opening extends radially from a position outer than the head when the valve disc is viewed axially from the upstream side to a position overlapping the circumferential surface of the portion of the head where the diameter becomes smaller when the valve disc is viewed axially from the downstream side. According to the fifth aspect, the opening can be opened to its maximum extent within a limited outer diameter of the entire check valve. Therefore, the check valve can achieve a high Cv value.

[0107] The present invention can realize on / off control of fluid flow in both the axial and radial directions while substantially maintaining flow near the valve seat. The present invention, which has such effects, can also be applied to liquid hydrogen, which is a cryogenic fluid, and is expected to contribute to the achievement of, for example, Goal 7 "Affordable and clean energy" and Goal 9 "Industry, innovation and infrastructure" of the Sustainable Development Goals (SDGs) advocated by the United Nations. [Example]

[0108] A check valve 1 corresponding to embodiment 1 was prepared. In this example, the first pipe section 10 and the second pipe section 20 were made of transparent acrylic resin in order to visually confirm the stability (low vibration) of the valve element 30 provided in the check valve 1 of embodiment 1.

[0109] A comparative check valve 1000 was also prepared. The comparative check valve 1000 differs from the check valve 1 of the embodiment only in that it does not have the flow rectifying section 333 and the inner end face on the upstream side of the body is flat.

[0110] <Checking the positional fluctuation of the valve disc when the valve is open> A test was conducted on the check valve 1 of this example and the check valve 1000 for comparison, in which water was flowed as a fluid under a differential pressure of approximately 65 kPa, and the results were videotaped. The obtained video was visually inspected. As a result, for the check valve 1000 of the comparative example, fluctuations of the valve disc in a direction perpendicular to the flow path were visually observed approximately 20 times per 10 seconds with an irregular period and amplitude of approximately 0.2 to 0.5 mm. On the other hand, no such fluctuations were visually observed for the check valve 1 of this example.

[0111] <Fluid analysis> Fluid analysis (FEM analysis) was performed on both Check Valve 1 and the comparative Check Valve 1000. Solid Works Flow Simulation 2019 SP5.0 was used as the analysis software. The analysis conditions were set as follows: water was used as the fluid, the valve disc stroke (the distance between the tip of the valve disc and the valve seat) was 8 mm, the pressure difference between the primary and secondary sides was 250 kPa, and the force pushing the valve disc was 46.12 N.

[0112] The analysis results using the check valve 1 of this embodiment are shown in Fig. 19, and the analysis results using the comparative check valve 1000 are shown in Fig. 20. In Figs. 19 and 20, lower flow velocities are shown in black, and faster flow velocities are shown in white.

[0113] 19 and 20, it can be seen that in the comparative check valve 1000, a vortex (the area enclosed by a dotted line in FIG. 20) is generated within the cylindrical portion 1321 behind the head portion 1031 of the valve element 1030. In contrast, in the check valve 1 of this embodiment, the fluid is rectified by the conical rectifying portion 333 behind the head portion 31, and it has been confirmed that no vortex is generated. [Explanation of symbols]

[0114] 1, 3 Check valve 10 First pipe section 11 Valve seat 20 Second pipe section 30, 230 Valve body 31, 231 head 32 Body (connecting part) 40 Coil spring 50 Protrusion 51 Tip 52 Proximal end 311 Periphery 312 First recess 313 Second Recess 314 Third Recess 315 Projection part 321 Cylindrical part 322 Center 323 Connecting part 324 Opening 325 Ribs 333 Rectifier section 511 Fourth Recess 512 Through hole S center axis

Claims

1. a second pipe section having an inner diameter larger than that of the first pipe section and connected to the downstream side of the first pipe section; a valve element housed in the second pipe section and movable within the second pipe section in the axial direction of the second pipe section; and a biasing member housed in the second pipe section and biasing the valve element toward the first pipe section to seat it on the valve seat, the valve element has a head portion seated on the valve seat, a communication portion including an opening portion located downstream of the head portion and communicating between the upstream side and the downstream side of the second pipe portion along the axial direction, and a flow straightening portion located in the communication portion at a position downstream of the head portion, The head portion and the flow rectifying portion each have a cross-sectional shape perpendicular to the axial direction, the diameter of which decreases toward the downstream side.

2. 2. The check valve according to claim 1, wherein a difference between a flow path area of ​​the second pipe section in a cross section perpendicular to the axial direction and a projected area of ​​the head section when viewed from the upstream side along the axial direction is defined as a first flow path area, and an opening area of ​​the opening section is defined as a second flow path area, and the first flow path area is 0.9 to 1.1 times the second flow path area.

3. the communicating portion is a cylindrical body portion that is slidable into the second pipe portion, the opening is located at the upstream end of the body; The check valve according to claim 1 , wherein the flow regulating portion is located at an upstream end portion within the body portion.

4. The check valve according to claim 1 , wherein the flow regulating portion has a tapered outer shape in which the diameter gradually decreases from the upstream side to the downstream side.

5. 2. The check valve according to claim 1, wherein the opening extends radially from a position outer than the head when the valve body is viewed in the axial direction from the upstream side to a position overlapping with the peripheral surface of the portion of the head where the diameter becomes smaller when the valve body is viewed in the axial direction from the downstream side.

Images