Check valve

Abstract

To provide a compact check valve having a high Cv value.SOLUTION: A check valve (1) includes a configuration in which a valve body (30) within a second pipe section (20) is urged toward a valve seat (11) on the side of a first pipe section (10). The valve body (30) includes: a head portion (31) whose radial dimension decreases toward a downstream side; and a cylindrical portion (32) connected with the downstream side of the head portion. The flow path area at the upstream end of the head portion (31) is 0.9 to 1.1 times the flow path area of a communication port (324) that constitutes the flow path on the cylindrical portion (32) side.SELECTED DRAWING: Figure 4

Description

Technical Field

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

Background Art

[0002] In recent years, technologies using liquid hydrogen, such as hydrogen stations for automotive fuel cells, have been studied and are being popularized. In equipment using liquid hydrogen, various valves such as flow control valves and check valves are used. As a check valve applicable to liquid hydrogen, there is known a check valve that biases a valve body in a direction opposite to the fluid flow direction in a fluid flow path to seat on a valve seat, and allows fluid to flow from the outer flow path of the valve body to the inner flow path of the valve body when the valve is opened (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Even for a check valve for liquid hydrogen, it is required to allow liquid hydrogen to flow easily when the valve is opened, for example, to have a high Cv value. The conventional technology as described above leaves room for improvement from the viewpoint of increasing the Cv value.

[0005] One aspect of the present invention aims to realize a small-sized check valve having a high Cv value.

Means for Solving the Problems

[0006] In order to solve the above problems, a check valve according to one aspect of the present invention includes a first pipe portion through which a fluid flows, a valve seat located at an opening edge portion of the downstream end of the first pipe portion, a second pipe portion having an inner diameter larger than that of the first pipe portion and connected to the downstream side of the first pipe portion, a valve body accommodated in the second pipe portion and movable in the axial direction of the second pipe portion within the second pipe portion, and a biasing member accommodated in the second pipe portion and biasing the valve body toward the first pipe portion to seat the valve body on the valve seat. The valve body has a head portion that seats on the valve seat and a body portion located on the downstream side of the head portion. The head portion has a shape in which the diameter of a cross section orthogonal to the axial direction decreases toward the downstream side. The body portion has a communication port that opens in the axial direction and communicates the upstream side and the downstream side of the second pipe portion. When the valve is open, a fluid flow path is formed that passes through the inside of the body portion through the communication port from the outer peripheral side of the head portion. The communication port opens in the radial direction from a position on the outer peripheral side of the head portion when the valve body is viewed axially from the upstream side to a position overlapping the peripheral surface of a portion where the diameter of the head portion becomes smaller when the valve body is viewed axially from the downstream side.

Effect of the Invention

[0007] According to one aspect of the present invention, it is possible to realize a check valve that is small in size and has a high Cv value.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

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Figure 4

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Figure 8

Figure 9

Figure 10

Figure 11

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Figure 14

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Figure 16

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Figure 20

Mode for Carrying Out the Invention

[0009] 〔Embodiment 1〕 Hereinafter, an embodiment of the present invention will be described in detail. A front view of the check valve according to Embodiment 1 of the present invention is shown in FIG. 1, a plan view in FIG. 2, and a right side view in FIG. 3. The check valve 1 has a first pipe portion 10 and a second pipe portion 20. The first pipe portion 10 and the second pipe portion 20 are made of a material having sufficient strength, for example, both are made of stainless steel.

[0010] The first pipe portion 10 is a portion of the pipe through which the fluid flows. The second pipe portion 20 is also a portion of the pipe through which the fluid flows. It has an inner diameter larger than that of the first pipe portion and is connected to the downstream side of the first pipe portion. The first pipe portion 10 and the second pipe portion 20 are, for example, in a state with a packing therebetween, and are directly connected in a straight tubular shape by screwing together a first screw portion formed on the outer peripheral surface of the first pipe portion 10 and a second screw portion formed on the upstream end portion of the inner peripheral surface of the second pipe portion 20. Inside the second pipe portion 20, a valve body 30 is accommodated.

[0011] In the following description, the central axis S of the check valve 1 is also simply referred to as the "axis". Also, the side of the first pipe portion 10 in the check valve 1 is the upstream side in the fluid flow direction, and the side of the second pipe portion 20 in the check valve 1 is the downstream side in the fluid flow direction. In the following description, the positions in the axial direction may be expressed by "upstream" and "downstream".

[0012] FIG. 4 shows a cross section when the check valve 1 in FIG. 1 is cut along the line A-A in FIG. 1. A cylindrical space is formed inside the first pipe portion 10. Also, the pipe wall on the downstream side of the first pipe portion 10 is thicker than that on the upstream side. The first pipe portion 10 has a valve seat 11 at the opening edge portion of its downstream end. The valve seat 11 is a portion extending over the entire circumference of the opening edge portion of the downstream end of the first pipe portion 10 and is disposed at a position facing the peripheral edge portion at the upstream end of the head 31 of the valve body 30 described later.

[0013] The valve body 30 is accommodated in the second pipe portion 20 so as to be movable in the axial direction of the second pipe portion 20 within the second pipe portion 20. Further, a coil spring 40 that presses the valve body 30 toward the valve seat 11 is disposed within the second pipe portion 20. The downstream end of the coil spring 40 is fitted inside the downstream end portion of the second pipe portion 20, and the upstream end of the coil spring 40 abuts against the valve body 30 to bias the valve body 30 toward the upstream side. The coil spring 40 corresponds to a biasing member that biases the valve body 30 toward the first pipe portion 10 and seats it on the valve seat 11.

[0014] A perspective view of the valve body 30 is shown in FIG. 5, a cross section including the axis S of the valve body 30 is shown in FIG. 6, a left side view of the valve body 30 is shown in FIG. 7, and a right side view of the valve body 30 is shown in FIG. 8, respectively. The valve body 30 is an integrally molded resin product and has a head portion 31 and a body portion 32. The material of the valve body 30 may be any material that can exhibit sufficient sealing performance, and is appropriately determined according to the use of the check valve 1. In the present embodiment, the valve body 30 is an integrally molded product of a composition of a fluororesin (polytetrafluoroethylene (PTFE)) containing carbon fiber as a filler, for example.

[0015] The head portion 31 is the upstream portion of the valve body 30. The head portion 31 has a shape in which the diameter of the cross section orthogonal to the axial direction decreases toward the downstream side. More specifically, the head portion 31 has a tapered outer shape in which the diameter gradually decreases from the upstream side toward the downstream side. Thus, the head portion 31 has a substantially frustoconical shape with the upstream side as the bottom. The outer diameter at the upstream end of the head is equal to or slightly larger than the outer diameter of the valve seat 11.

[0016] The head portion 31 has, at its upstream end portion, a peripheral edge portion 311, a first concave portion 312, a second concave portion 313, and a third concave portion 314 when viewed from the outside along the axial direction. The peripheral edge portion 311 is an annular portion when viewed along the axial direction and is a flat planar portion in a direction orthogonal to the axis S. Thus, the peripheral edge portion 311 is configured to contact the valve seat 11 over the entire circumference when the valve body 30 advances toward the valve seat 11. Thus, the valve body 30 has a head portion 31 that seats on the valve seat 11.

[0017] The first recess 312 is a portion that is recessed downstream from the inner periphery of the peripheral portion 311, and forms an annular recess inside the peripheral portion 311. The second recess 313 is a portion that is recessed further downstream from the inner periphery of the first recess 312, and forms a circular recess inside the first recess 312. The third recess 314 is a portion that is recessed downstream from the central portion on the bottom surface of the second recess 313, and forms a cylindrical recess at the central portion of the bottom surface of the second recess 313.

[0018] The body portion 32 is located downstream of the head portion 31, 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 portion 31. The body portion 32 is a cylindrical portion that is slidable on the inner peripheral wall of the second pipe portion 20 at its outer peripheral wall, and has a cylindrical portion 321 that communicates the upstream side and the downstream side of the second pipe portion 20.

[0019] Further, the body portion 32 has, at the upstream end of the cylindrical portion 321, a substantially circular central portion 322 when viewed along the axial direction, and connecting portions 323 that connect the cylindrical portion 321 and the central 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. Also, the head portion 31 is connected to the central portion 322.

[0020] Furthermore, the body portion 32 has three communication ports 324 surrounded by the cylindrical portion 321, the central portion 322, and the connecting portions 323. The communication ports 324 are located at the upstream end of the body portion 32 in the axial direction, open along the axial direction, and communicate the space upstream of the body portion 32 in the second pipe portion 20 and the space inside the cylindrical portion 321. Here, "open along the axial direction" means that the communication ports 324 are formed by an opening surrounded by a circumferential wall surface substantially parallel to the axial direction provided on the upstream end surface of the body portion 32. That is, the communication ports 324 communicate the space upstream and downstream of the body portion 32 in the second pipe portion 20 through the internal space of the cylindrical portion 321. In this way, the body portion 32 has communication ports 324 that open in the axial direction and communicate the upstream side and the downstream side of the second pipe portion 20.

[0021] The opening shape of the communication port 324 is a shape in which the track shape is curved in an arc shape in its longitudinal direction, and the shape of its end portion is a substantially semi-circular shape with the width of the communication port 324 as the diameter. In this way, the opening shape of the communication port 324 is composed of continuous curves. The communication port 324 is provided such that its outer diameter side is located on the outer diameter side of the maximum diameter portion (peripheral portion 311) of the head 31, and its inner diameter side is located in a region where the diameter of the head 31 is smaller, preferably near the central portion 322. In this way, in the radial direction of the valve body 30, the communication port 324 opens from a position on the outer peripheral side of the head 31 when the valve body 30 is viewed along the axial direction from the upstream side to a position overlapping the peripheral surface of the portion where the diameter of the head 31 becomes smaller when the valve body 30 is viewed along the axial direction from the downstream side.

[0022] Here, the "peripheral surface of the portion where the diameter of the head 31 becomes smaller when the valve body 30 is viewed along the axial direction from the downstream side" refers to the portion of the side peripheral surface of the head 31 where the diameter is smaller than the maximum diameter portion. As long as the communication port 324 is provided at a position where its inner diameter side overlaps any part of such a side peripheral surface, the above-described conditions for the opening of the communication port 324 will be satisfied. In the present embodiment, the communication port 324 is formed to a position where its inner diameter side is close to the central portion 322, and this position is set to the maximum inner diameter side within a range where the strength of the connecting portion between the body portion 32 of the head 31 is not insufficient. Further, 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 described later.

[0023] Also, the body portion 32 has three ribs 325 protruding 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 portion of the cylindrical portion 321 to the vicinity of the central portion. The shape of the cross section orthogonal to the axial direction in the ribs 325 is substantially trapezoidal.

[0024] Note that the coil spring 40 has its downstream end fixed to the downstream end of the second pipe portion 20 as described above. The upstream portion thereof is inserted into the inside of the cylindrical portion 321 from the downstream side and is guided axially along the outer peripheral side by the top of the rib 325, and abuts against the central portion 322 at its upstream end in a state where the whole in the axial direction is contracted. In this way, the coil spring 40 abuts against the central portion 322 at its upstream end with its downstream end fixed in the axial direction, and biases the valve body 30 toward the upstream side. In this way, the coil spring 40 is held by the cylindrical portion 321 on the downstream side and is held by the rib 325 on the upstream side. Therefore, the coil spring 40 is in a state where the positions of the cores at both ends thereof are aligned with the center in the radial direction of the body portion 32, and it is difficult for displacement in the radial direction due to the deflection of the spring or the like to occur. Therefore, the peripheral edge portion 311 of the head portion 31 abuts accurately against the valve seat 11, and the sealing performance is further enhanced.

[0025] In this way, in the check valve 1, the valve body 30 is composed of the head portion 31 and the body portion 32, and the head portion 31 has a shape in which the diameter decreases from the valve seat 11 toward the body portion 32. The second pipe portion 20 constitutes a valve chamber for accommodating the valve body, and the body portion 32 has a cylindrical shape substantially equal to the inner diameter of the valve chamber. Further, a communication port 324 for communicating the space on the head portion 31 side and the space inside the body portion 32 along the axial direction is provided on the upstream end surface portion of the body portion 32 that is the boundary with the head portion 31 in the valve body 30. Therefore, when the valve is opened, a fluid flow path is formed in the check valve 1 that passes through the inside of the body portion 32 through the communication port 324 from the outer peripheral side of the head portion 31. In this way, in the check valve 1, in the axial direction from the valve seat 11 to the upstream end of the body portion 32, the fluid flows through the space (the space outside the valve body 30) formed between the inner peripheral surface of the valve chamber and the outer surface of the head portion 31, and on the downstream side of the upstream end of the body portion 32, the fluid flows through the inside of the body portion 32 of the valve body 30 (the space inside the valve body 30).

[0026] 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 the fluid can flow in a specific cross section orthogonal to the axial direction.

[0027] The first flow passage area A1 is the difference between the flow passage area of the second pipe portion 20 in a cross section orthogonal to the axial direction at the seating position of the head 31 and the projected area of the head 31 when viewed along the axial direction from the upstream side. Assuming that the outer diameter of the cylindrical portion 321 in the valve body 30 is substantially the same as the inner diameter of the second pipe portion 20, the first flow passage area A1 is, for example, the area of an annular region formed between the periphery of the cylindrical portion 321 and the outer edge of the peripheral portion 311 in FIG. 7.

[0028] The second flow passage area A2 is the opening area of the communication port 324 in a cross section orthogonal to the axial direction. If the opening area of one communication port 324 is S1, the second flow passage area A2 is represented by 3×S1. The second flow passage area A2 is, for example, the sum of the opening areas of the three communication ports 324 in FIG. 8.

[0029] If the difference between the first flow passage area A1 and the second flow passage area A2 is too large, the Cv value of the check valve 1 becomes small, and for example, the pressure loss due to the flow of the fluid increases. The Cv value is an inherent coefficient indicating the ease of fluid flow, and in this embodiment, it represents the capacity of the check valve 1. The difference between the first flow passage area A1 and the second flow passage area A2 may be a value that can achieve a Cv value corresponding to the use of the check valve 1 and the performance required for the check valve 1. From the viewpoint of realizing a Cv value equivalent to the theoretical value, it is preferable that the first flow passage area A1 is 0.9 to 1.1 times the second flow passage area A2.

[0030] Calculation formulas for the Cv value according to the type of fluid (such as liquid or gas) are widely known, and the theoretical value of the Cv value of the check valve 1 can be obtained based on such known formulas. Further, the Cv value of the check valve 1 can be measured based on a method defined in Japanese Industrial Standards (JIS) (for example, B2005-2-3).

[0031] Thus, the check valve 1 is characterized in that the first flow path area A1, which is the cross-sectional area in the space between the maximum diameter portion of the head 31 of the valve body 30 and the inner peripheral wall surface of the second pipe portion 20, and the second flow path area A2, which is the total opening area of the communication ports 324 on the upstream end face portion of the body portion 32, are substantially equal. The Cv value of a given flow path is affected by the cross-sectional area of the portion where the flow path is narrowest. In the structure of the check valve 1 of the present embodiment, either the first flow path area A1 or the second flow path area A2 becomes the portion where the flow path is narrowest. From the viewpoint of obtaining a high Cv value, either the first flow path area A1 or the second flow path area A2 that becomes narrower can be made as large as possible. Specifically, it is conceivable to increase the outer diameter of the second pipe portion 20. However, when the check valve 1 is applied to, for example, an automobile, a ship, or an aircraft, it is desirable that the overall diameter be as small as possible when there are limitations in the installation space. If the diameter of the second pipe portion 20 is small, the first flow path area A1, which can only have space on the outer diameter side of the head 31 of the valve body 30, will inevitably become small. If the communication port 324 is made too large in an attempt to increase the second flow path area A2, there is a risk that the strength of the connecting portion 323 and the like will be insufficient.

[0032] Therefore, in the check valve 1, the communication port 324 is formed to open from a position on the outer peripheral side of the head 31 in the radial direction of the valve body 30 to a position overlapping the peripheral surface of the portion where the diameter of the head 31 becomes smaller. In this way, in the present embodiment, within the limited overall outer diameter range, the communication port 324 can be substantially maximally opened. Therefore, a high Cv value can be realized with the check valve 1.

[0033] Also, in the check valve 1, the first flow path area A1 is set to be 0.9 to 1.1 times the second flow path area A2. In this way, in the check valve 1, within the limited overall outer diameter range, the first flow path area A1 and the second flow path area A2 are ensured to be as large as possible, and such a configuration also contributes to the realization of a high Cv value.

[0034] The taper angle on the tapered surface of the head 31 is defined as the angle formed by the outer peripheral surface of the head 31 with respect to the axial direction in a cross-section including the axis S. If the taper angle is too large, it is preferable from the perspective of miniaturizing the valve body 30 in the axial direction. However, since the flow in the direction perpendicular to the axial direction increases more with respect to the axial flow, the valve body 30 may be difficult to open, and the pressure loss of the fluid may increase. If the taper angle is too small, it is preferable from the perspective of easy opening of the valve body and suppressing the pressure loss of the fluid. However, the axial dimension of the valve body 30 increases. The taper angle can be appropriately determined from the perspectives of miniaturization, easy opening of the valve body, and suppression of fluid pressure loss. From the perspective of realizing these, the taper angle is preferably 60° or more.

[0035] [Valve opening and closing] The valve body 30 is biased from the downstream side toward the upstream side by the coil spring 40. Therefore, as shown in FIG. 4, the peripheral edge portion 311 is in close contact with the valve seat 11 over the entire circumference. In this way, when the fluid is not flowing, the check valve 1 is closed.

[0036] The state of the check valve 1 when the valve is opened is schematically shown in FIG. 9. When fluid is supplied to the first pipe portion 10, the internal pressure of the first pipe portion 10 rises. When the pressure of the fluid in the first pipe portion 10 exceeds a certain pressure (cracking pressure), the fluid pressure overcomes the biasing force of the coil spring 40, and the valve body 30 moves to the downstream side (right side in the figure). The fluid passes through the space on the outer peripheral side of the head 31 of the valve body 30 as indicated by the arrow in FIG. 9, flows into the cylindrical portion 321 through the communication port 324 of the body portion 32, and flows out to the downstream side of the second pipe portion 20 through the cylindrical portion 321.

[0037] [Main functions and effects] The check valve 1 has a valve body 30, and the valve body 30 has a body portion 32 on the downstream side. Therefore, when the valve is opened, a fluid flow path is formed that passes through the inside of the body portion 32 via the communication port 324 from the outer peripheral side of the head portion 31. In this way, the check valve 1 is configured to allow the fluid to flow through the space inside the body portion 32 of the valve body 30. The said space is a cylindrical space and substantially has no part that inhibits the flow of the fluid inside. Therefore, the check valve 1 can smoothly flow the fluid from the first pipe portion 10 toward the second pipe portion 20 when the valve is opened.

[0038] Also, the check valve 1 has a communication port 324 that opens axially on the upstream end surface of the body portion 32. Therefore, since it becomes possible to flow the fluid more linearly along the axial direction when the valve is opened, the check valve 1 can smoothly flow the fluid when the valve is opened.

[0039] Also, in the check valve 1, the head portion 31 of the valve body 30 has a shape in which the diameter decreases from the valve seat 11 toward the body portion 32. Therefore, without increasing the outer diameter of the valve body 30, the cross-sectional area of the flow path in the valve chamber (the cross-sectional area of the space between the inner peripheral surface of the second pipe portion 20 and the valve body 30) can be made sufficiently large.

[0040] The body portion 32 has a cylindrical portion 321. The cylindrical portion 321 has a peripheral wall that is slidable with respect to the inner peripheral wall of the second pipe portion 20 over the entire circumference. Therefore, it is suitable from the viewpoint of preventing the occurrence of play in the head portion 31 that receives the fluid pressure when the valve is opened and smoothly moving the valve body 30 along the axial direction when the valve is opened and closed.

[0041] Further, the body portion 32 has a rib 325 extending downstream from the connecting portion 323. Thus, it is suitable from the viewpoint of reinforcing the connecting portion 323 and from the viewpoint of reinforcing the upstream portion of the cylindrical portion 321. Further, the rib 325 restricts the movement of the coil spring 40 in the outer peripheral direction by the amount of the protruding height from the inner peripheral surface of the cylindrical portion 321. Thus, the fact that the body portion 32 has the rib 325 is suitable from the viewpoint of maintaining the position of the coil spring 40 within the body portion 32 closer to the radial center, accurately expressing the desired biasing force of the coil spring 40 on the valve body 30, and expressing the desired responsiveness of the check valve 1.

[0042] Also, in the check valve 1, the communication port 324 is configured to open substantially maximally in the radial direction of the valve body 30. Thus, in the check valve 1, it is possible to sufficiently increase the cross-sectional area of the flow path defined by the communication port 324. Therefore, the check valve 1 can achieve a high Cv value.

[0043] Furthermore, in the check valve 1, the first flow path area A1 and the second flow path area A2 are of the same degree. Therefore, the Cv value realized by the cross-sectional area of the flow path in the axial direction at the valve seat that becomes the first flow path area A1 is substantially maintained also at the communication port 324 that becomes the second flow path area A2 where the flow path is then narrowed. Thus, the check valve 1 can substantially achieve the target Cv value ensured by the flow path in the axial direction at the valve seat.

[0044] The magnitude of the Cv value is determined by the cross-sectional area of the throttling portion in the flow path of the valve. In the check valve 1, the cross-sectional area of the cross-section orthogonal to the axial direction in each of the flow paths, namely, the flow path of the fluid in the axial direction near the valve seat (the portion with the first flow path area A1), the flow path composed of the communication port 324 on the downstream side thereof (the portion with the second flow path area A2), and the flow path located between them and leading from the head 31 toward the body 32 along the head 31, are factors that affect the Cv value. In particular, the portion with the first flow path area A1 and the portion with the second flow path area A2 are throttling portions where the cross-sectional area of the fluid flow path decreases. Therefore, making the cross-sectional areas of these portions equal is suitable for maximizing these cross-sectional areas and is effective for efficiently ensuring the Cv value of the check valve 1.

[0045] In the check valve 1, the inner diameter of the second pipe portion 20 can be determined from the viewpoint of ensuring the first flow path area A1 that can obtain the target Cv value while ensuring the minimum outer diameter of the valve seat 11. In the check valve 1, between the portion with the first flow path area A1 and the portion with the second flow path area A2 in the axial direction, the flow path area gradually increases, but in the portion with the second flow path area A2, the flow path narrows again. In the check valve 1, by making the second flow path area A2 (the total opening area of the communication ports 324) equal to the first flow path area A1, it becomes possible to obtain the target Cv value ensured by the first flow path area A1.

[0046] In the check valve 1, by determining the first flow path area A1 corresponding to the target Cv value as described above, the inner diameter of the second pipe portion 20 is determined, and the outer diameter of the body 32 that 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 in the communication port 324 can be made larger, and it becomes easier to ensure a large Cv value. However, as a result, the check valve 1 becomes larger. Also, if the fluid flow velocity in the second pipe portion 20 is increased by making the body 32 thicker, there is a possibility that the fluid pressure decreases and the valve body 30 becomes difficult to open. Therefore, it is advantageous from the viewpoints of miniaturization and enhancing the sensitivity (responsiveness to fluid pressure) of the check valve 1 to make the outer diameter of the body 32 approximately the same as the inner diameter of the second pipe portion 20 determined based on the first flow path area A1.

[0047] In the case of determining the outer diameter of the body portion 32 in this way, in order to ensure a sufficient second flow path area A2, a flow path having a sufficient spread in the radial direction, particularly on the center side, is required. In the check valve 1, since the head portion 31 has a shape in which the diameter of the cross section orthogonal to its axial direction gradually decreases toward the downstream side, it is possible to form a communication port 324 that spreads toward the center side in the radial direction on the downstream side thereof (the upstream end portion of the body portion 32).

[0048]

[0048] As described above, the check valve 1 is easy to flow fluid when the valve is opened even if it is small, and thus it is possible to obtain a large Cv value. Therefore, the check valve 1 is suitable as a check valve that can be lightweight, miniaturized, and flow a large amount of fluid. The check valve 1 can be applied to applications where such characteristics are required, and is suitable as a check valve for aircraft mounting, for example.

[0049] Hereinafter, other embodiments of the present invention will be described. For convenience of explanation, in the following embodiments, members having the same functions as the members described in the previous embodiments are given the same reference numerals, and the description thereof will not be repeated.

[0050] 〔Embodiment 2〕 The check valve of the present embodiment has the same configuration as the check valve 1 of the first embodiment described above, except that a ridge portion is provided around the peripheral edge of the head portion of the valve body 30 and abuts on the valve seat when the head portion is seated.

[0051] A perspective view of the valve body in the present embodiment is shown in FIG. 10, and a cross section including the axis S of the valve body is shown in FIG. 11. Further, a portion B in FIG. 11 is enlarged and shown in FIG. 12. The check valve of the present embodiment has a valve body 230. The valve body 230 is configured in the same manner as the valve body 30 of the first embodiment described above, except that it has a head portion 231. The head portion 231 is configured in the same manner as the head portion 31 of the first embodiment described above, except that it further has a ridge portion 315.

[0052] The protrusion 315 is formed over the entire circumference at the central portion in the radial direction of the peripheral edge portion 311. The protrusion 315 has a substantially semi-circular cross-sectional shape. The curvature R in the cross-sectional shape of the protrusion 315 is set according to the surface pressure obtained when the valve body 230 is seated.

[0053] FIG. 13 schematically shows the contact state of the head 231 with respect to the valve seat 11 when the valve body 230 of the present embodiment is seated. In the state where the valve body 230 is seated on the valve seat 11, the protrusion 315 abuts against the valve seat 11 over the entire circumference. Further, since the valve body 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 respect to the valve seat 11.

[0054] Therefore, in the present embodiment, compared with the first embodiment, a seal closer to linearity is realized by the seating of the valve body 230, and the surface pressure of the valve body 230 against the valve seat 11 is further increased. Further, even when the temperature of the fluid is low and the valve body 230 thermally contracts, since the substantially semi-circular shape of the cross-section of the protrusion 315 is maintained and a part of it contacts the valve seat 11, a linear seal as described above is similarly formed. Therefore, the check valve according to the present embodiment has the same effect as the first embodiment and is more suitable as a check valve for cryogenic fluids such as liquid hydrogen than the check valve 1 of the first embodiment.

[0055] 〔Embodiment 3〕 The check valve of the present embodiment has the same configuration as the check valve 1 of the first embodiment described above, except that it further has a protrusion 50. The protrusion 50 is preferably made of a material having sufficient strength, for example, made of stainless steel.

[0056] The check valve of the present embodiment is shown in FIG. 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.

[0057] Fig. 15 shows a cross-section including the axis S of the protrusion 50. The protrusion 50 has an upstream tip 51 and a downstream base end 52.

[0058] The tip 51 has a circular shape when viewed along the axial direction and has a substantially trapezoidal shape with a gradually decreasing diameter toward the upstream side when viewed from a direction perpendicular to the axis S. The diameter at the downstream end of the tip 51 is approximately equal to the diameter of the first recess 312 and is slightly smaller than the diameter of the first recess 312. Also, the taper angle on the peripheral surface of the tip 51 is about several degrees. The method of determining the taper angle will be described later.

[0059] The tip 51 has a fourth recess 511 on its upstream end face. The fourth recess 511 is a circular recess when viewed along the axial direction and has a diameter smaller than the diameter of the upstream end face of the tip 51. Also, the fourth recess 511 has a depth approximately equal to that of the first recess 312 of the head 31.

[0060] The base end 52 is a cylindrical portion continuous with the downstream side of the tip 51. The diameter of the base end 52 is approximately equal to the diameter of the second recess 313 and is slightly smaller than the diameter of the second recess 313. Also, the thickness of the base end 52 is approximately equal to the depth of the second recess 313.

[0061] Also, the protrusion 50 has a circular through-hole 512 in the central portion when viewed along the axial direction. The through-hole 512 has a diameter approximately equal to that of the third recess 314 of the head 31.

[0062] The protrusion 50 is fixed to the upstream end of the head 31 by a fixing member such as a pin or a screw that fits the base end 52 into the second recess 313 and is inserted into the through-hole 512 from the upstream side to reach the third recess 314.

[0063] The axial position of the protruding portion 50 when the check valve 3 is closed is shown in Fig. 16. Since the protruding portion 50 is attached to the upstream end of the head 31, in the state where the head 31 is seated on the valve seat 11, the tip portion 51 reaches a position further upstream than the valve seat 11. Since the peripheral wall of the tip portion 51 has a tapered surface as described above, a gap is formed between the protruding portion 50 and the inner peripheral wall surface of the first pipe portion 10. Thus, the check valve 3 has a protruding portion 50 disposed at the upstream end of the head 31 and entering the first pipe portion 10 when the valve body of the head 31 is seated. And the protruding portion 50 enters the first pipe portion 10 so as to form a gap between the protruding portion 50 and the inner peripheral wall surface of the first pipe portion 10.

[0064] The axial position of the protruding portion 50 when the check valve 3 is slightly opened is shown in Fig. 17. In the state where fluid is supplied to the first pipe portion 10 and the valve body 30 is slightly detached from the valve seat 11, the fluid flows through the gap between the inner peripheral wall surface of the first pipe portion 10 and the tapered surface of the tip portion 51. During this time, since the fluid is being supplied to the first pipe portion 10, the pressure of the fluid in the first pipe portion 10 increases according to the supply amount of the fluid.

[0065] On the other hand, since the valve body 30 is biased upstream by the coil spring 40, the axial position of the valve body 30 is determined according to the extension force of the coil spring 40. Therefore, in the state shown in Fig. 17, the valve body 30 receives from the fluid a pressure to move downstream by the thickness of the tip portion 51.

[0066] Since the protruding portion 50 has a gap with the inner peripheral wall surface of the first pipe portion 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 opened. Even when the valve body 30 is seated on the valve seat 11 (when the valve is closed), since the protruding portion 50 enters the first pipe portion 10 immediately before the valve body 30 is seated on the valve seat 11, a gap is formed between the inner peripheral wall surface of the first pipe portion 10 and the protruding portion 50, and the flow rate of the fluid is restricted in the same way as when the valve is open.

[0067] Fig. 18 shows the axial position of the protruding portion 50 when the check valve 3 is fully open. When the protruding portion 50 is located downstream of the valve seat 11, the aforementioned gap is eliminated, and the fluid flows at the same flow rate as when the valve body 30 without the protruding portion 50 opens and closes.

[0068] Thus, in the check valve 3, a protruding portion 50 having a diameter slightly smaller than the inner diameter of the first pipe portion 10 is provided on the head portion 31 of the valve body 30 facing the valve seat 11, and the protruding portion 50 protrudes into the first pipe portion 10 when the valve body 30 seats on the valve seat 11. By providing such a protruding portion 50, when the valve body 30 is slightly opened, the fluid flows through the narrow gap between the inner peripheral wall of the first pipe portion 10 and the outer peripheral wall of the protruding portion 50. Therefore, the flow rate of the fluid when the valve body 30 is slightly opened is restricted. When the valve body 30 further moves in the opening direction (downstream side) and the protruding portion 50 disengages from the first pipe portion 10, the opening between the valve seat 11 and the head portion 31 of the valve body 30 suddenly becomes larger, and the flow rate of the fluid increases all at once. Thus, in the check valve 3, the flow rate suddenly increases at a specific opening degree when the valve is opened. 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 all at once when a predetermined opening degree is exceeded.

[0069] The degree of such switching performance is determined by the size of the gap between the protruding portion 50 and the inner peripheral wall surface of the first pipe portion 10, and the smaller the gap, the more prominent the on-off switching becomes. In the embodiment, the peripheral surface of the tip portion 51 is a tapered surface, and the size of the gap is determined by the taper angle. And as the taper angle increases, the gap also increases. Thus, the taper angle of the tip portion 51 is determined according to the desired degree of on-off switching performance.

[0070] If the gap is too small, the protruding portion 50 may come into contact with the valve seat 11 when the valve is closed and may not be able to enter the first pipe portion 10. However, in the present embodiment, the peripheral surface of the tip portion 51 is a tapered surface. Therefore, when the valve is closed, the protruding portion 50 easily enters the first pipe portion 10, and while ensuring a minute gap between the protruding portion 50 and the inner peripheral wall surface of the first pipe portion 10, contact between the protruding portion 50 and the valve seat 11 when the valve is closed is prevented. Thus, even if the valve body 30 further has the protruding portion 50, the opening and closing accuracy of the valve body 30 is sufficiently maintained.

[0071] Further, the protruding portion 50 has a substantially disc-shaped structure as described above. When the fluid is a low-temperature fluid such as liquid hydrogen, the valve body 30 may thermally contract and affect the sealing performance of the valve body 30. Since the check valve 3 has the protruding portion 50 having high rigidity at the upstream end of the head portion 31 of the valve body 30, it is suitable from the viewpoint of suppressing the radial deformation of the head portion 31 due to heat.

[0072] 〔Other Embodiments〕 The protruding portion 50 in the check valve 3 according to Embodiment 3 may be further applied to the protruding strip portion 315 in Embodiment 2. Such a check valve exhibits both the effects of Embodiment 2 and the effects of Embodiment 3.

[0073] The body portion 32 does not have to be cylindrical. The body portion 32 may be a plate-shaped member having the communication port 324, or may be a member having a sliding portion that extends in the axial direction and slides with respect to the inner peripheral surface of the second pipe portion 20 in addition to the plate-shaped member. Note that it is preferable that the sliding portions are at symmetric positions in the radial direction (rotationally symmetric positions centered on the axis S in a cross section orthogonal to the axial direction) from the viewpoint of suppressing radial displacement when the valve body 30 is opened and closed.

[0074] The change in the diameter of the cross section orthogonal to the axial direction in the head portion 31 does not have to be a linear change, and may be a curved change (for example, a gourd shape). Further, the change in the diameter does not have to be continuous, and may be a discontinuous change (for example, a stepped shape).

[0075] Instead of the protruding strip 315 in Embodiment 2, a protruding strip that protrudes from the valve seat 11 over the entire circumference may be formed. In this way, in the sealing portions where the valve seat 11 and the head 31 are in contact with each other, either one may be convex and the other may be flat. Also, these protruding strips do not necessarily have a semicircular cross section, and may have a V-shaped cross section or the like.

[0076] In Embodiment 3, the protruding portion 50 does not have to be a plate-like member. For example, the protruding portion may be a member that forms a gap as described above between the inner peripheral wall surface of the first pipe portion 10 (for example, an annular member having the outer peripheral surface of the tapered surface described above).

[0077] As described above, the present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in 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.

[0078] 〔Summary〕 A first aspect of the present invention is a check valve (1) having a first pipe portion (10) through which a fluid flows, a valve seat (11) located at the opening edge of the downstream end of the first pipe portion, a second pipe portion (20) having an inner diameter larger than that of the first pipe portion and connected to the downstream side of the first pipe portion, a valve body (30) housed in the second pipe portion and movable in the axial direction of the second pipe portion within the second pipe portion, and a biasing member (coil spring 40) housed in the second pipe portion and biasing the valve body toward the first pipe portion to seat on the valve seat. The valve body has a head (31) that seats on the valve seat and a body portion (32) located on the downstream side of the head. The head has a shape in which the diameter of a cross section perpendicular to the axial direction decreases toward the downstream side. The body portion has a communication port (324) that opens axially to communicate the upstream side and the downstream side of the second pipe portion. When the valve is open, a fluid flow path is formed that passes through the inside of the body portion through the communication port from the outer peripheral side of the head. The communication port opens from a position on the outer peripheral side of the head when the valve body is viewed axially from the upstream side to a position overlapping the peripheral surface of a portion where the diameter of the head decreases when the valve body is viewed axially from the downstream side. According to the first aspect, a check valve that is small and has a high Cv value can be realized.

[0079] In a second aspect of the present invention, in the first aspect, when the difference between the flow passage area of the second pipe portion in a cross section orthogonal to the axial direction at the seating position of the head and the projected area of the head when viewed along the axial direction from the upstream side is defined as the first flow passage area and the opening area of the communication port is defined as the second flow passage area, the first flow passage area is 0.9 to 1.1 times the second flow passage area, and it is a backflow prevention valve. The second aspect is more effective from the viewpoint of realizing the target Cv value.

[0080] In a third aspect of the present invention, in the first aspect or the second aspect, the body portion is a cylindrical portion slidable in the second pipe portion, and the communication port is located at the upstream end of the body portion. In the third aspect, the portion where the flow passage area is minimized in the axial direction can be concentrated at the end of the head in the axial direction. Therefore, the third aspect is more effective from the viewpoint of realizing miniaturization, particularly miniaturization in the axial direction.

[0081] In a fourth aspect of the present invention, in any one of the first aspect to the third aspect, the head has a tapered outer shape in which the diameter gradually decreases from the upstream side to the downstream side. In the fourth aspect, it is possible to sufficiently secure the flow passage area between the upstream side and the downstream side of the head in the axial direction without accompanying an increase in the size of the second pipe portion in the radial direction. Therefore, the fourth aspect is more effective from the viewpoint of realizing a flow with a high Cv value.

[0082] In a fifth aspect of the present invention, in any one of the first aspect to the fourth aspect, it further has a ridge portion (315) provided around the peripheral edge of the head and contacting the valve seat when the head is seated. In the fifth aspect, it becomes possible to form a linear seal portion between the valve seat and the valve body, and the surface pressure in the seal portion is increased. Therefore, the fifth aspect is more effective from the viewpoint of enhancing the sealing performance.

[0083] The sixth aspect of the present invention is any one of the first to fifth aspects, further having a protrusion disposed at the upstream end of the head and entering the first pipe portion when the valve body of the head is seated, and the protrusion enters the first pipe portion so as to form a gap between the protrusion and the inner peripheral wall surface of the first pipe portion. In the sixth aspect, the flow rate of the fluid flowing until the protrusion detaches from the first pipe portion to the second pipe portion or until the valve body seats toward the valve seat is suppressed to the flow rate flowing through the gap. Therefore, the sixth aspect is more effective from the viewpoint of enhancing the on-off characteristics of the check valve.

[0084] In the present invention, it is possible to realize on-off of the fluid flow so as to substantially maintain the flow in the vicinity of the valve seat in both the axial direction and the radial direction. The present invention having such an effect is applicable also to liquid hydrogen which is an extremely low temperature fluid, and is expected to contribute to the achievement of, for example, Goal 7 "Ensure access to affordable, reliable, sustainable and modern energy for all" and Goal 9 "Build resilient infrastructure, promote inclusive and sustainable industrialization and foster innovation" proposed by the United Nations.

Example

[0085] A check valve corresponding to Embodiment 1 and a check valve provided with the protrusion of Embodiment 3 (a check valve corresponding to Embodiment 3) were prepared. The thickness of the tip portion of the protrusion is 2 mm.

[0086] For each check valve, with the fluid conditions being the same, the opening degree (stroke (the position from the valve seat in the axial direction when the valve body moves away from the valve seat to the downstream side)) and the theoretical value of the Cv value at that time were obtained. Then, the Cv values at the time of valve closing and valve opening were actually measured according to the above fluid conditions.

[0087] The theoretical values and measured values of the Cv value of the check valve corresponding to Embodiment 1 are shown in FIG. 19. Also, the theoretical values and measured values of the Cv value of the check valve corresponding to Embodiment 3 are shown in FIG. 20. In the figures, the broken line indicates the theoretical value of the Cv value, the one-dot chain line indicates the actually measured value of the Cv value at the time of valve closing, and the solid line indicates the actually measured value of the Cv value at the time of valve opening.

[0088] As is clear from FIG. 19, in the check valve of Embodiment 1, flow characteristics with a Cv value substantially equivalent to the theoretical value can be obtained regardless of whether the valve is open or closed. Therefore, it can be understood that the check valve of Embodiment 1 allows fluid to flow so as to achieve a desired Cv value while being small in size.

[0089] As is clear from FIG. 20, in the check valve of Embodiment 3, flow characteristics with a Cv value similar to the theoretical value can be obtained regardless of whether the valve is open or closed. Particularly when the stroke is small (<2 mm), the measured values tend to be lower than the theoretical values both when the valve is open and when it is closed. Therefore, it can be understood that the check valve of Embodiment 3 is excellent from the viewpoint of improving the on-off property of the flow.

Explanation of Reference Numerals

[0090] 1, 3 Check valve 10 First pipe portion 11 Valve seat 20 Second pipe portion 30, 230 Valve body 31, 231 Head 32 Barrel 40 Coil spring 50 Protrusion 51 Tip 52 Base end 311 Peripheral edge 312 First recess 313 Second recess 314 Third recess 315 Ridge 321 Cylindrical portion 322 Central portion 323 Connecting portion 324 Communication port 325 Rib 511 Fourth recess 512 Through hole S Central axis

Claims

1. A check valve having a first pipe portion through which a fluid flows, a valve seat located at an opening edge of a downstream end of the first pipe portion, a second pipe portion having an inner diameter larger than that of the first pipe portion and connected to the downstream side of the first pipe portion, a valve body accommodated in the second pipe portion and movable axially of the second pipe portion within the second pipe portion, and a biasing member accommodated in the second pipe portion for biasing the valve body toward the first pipe portion to seat the valve body on the valve seat, wherein the valve body has a head portion that seats on the valve seat and a body portion located downstream of the head portion, the head portion has a shape in which the diameter of a cross section orthogonal to the axial direction decreases toward the downstream side, the body portion has a communication port that opens axially and communicates the upstream side and the downstream side of the second pipe portion, when the valve is open, a fluid flow path is formed that passes through the inside of the body portion through the communication port from the outer peripheral side of the head portion, the communication port opens in the radial direction from a position on the outer peripheral side of the head portion when the valve body is viewed axially from the upstream side to a position overlapping the peripheral surface of a portion where the diameter of the head portion becomes smaller when the valve body is viewed axially from the downstream side, A check valve.

2. When a difference between a flow path area of the second pipe portion in a cross section orthogonal to the axial direction at the seating position of the head portion and a projected area of the head portion when viewed axially from the upstream side is defined as a first flow path area and an opening area of the communication port is defined as a second flow path area, the first flow path area is 0.9 to 1.1 times the second flow path area. The check valve according to Claim 1.

3. The body portion is a cylindrical portion slidable in the second pipe portion, and the communication port is located at an upstream end of the body portion. The check valve according to Claim 1.

4. The head portion has a tapered outer shape in which the diameter gradually decreases from the upstream side toward the downstream side. The check valve according to Claim 1.

5. The check valve according to Claim 1, further comprising a protruding strip portion provided around a peripheral edge portion of the head portion and contacting the valve seat when the head portion seats.

6. The check valve according to Claim 1, further comprising a protruding portion disposed at an upstream end of the head portion and entering the first pipe portion when the valve body seats on the head portion, and the protruding portion enters the first pipe portion so as to form a gap between the protruding portion and an inner peripheral wall surface of the first pipe portion.

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