Check valve

Abstract

To provide a check valve opened with a small force, and restraining a backflow.SOLUTION: The check valve comprises: a casing 1 having a valve chamber 25 and a valve hole 26 formed on the valve chamber 25; a valve body 31 provided in the valve chamber 25, and opening / closing the valve hole 26 by displacing a portion between a closed position for closing the valve hole 26 and a full-open position for fully opening the valve hole 26; and an energization mechanism (51, 42) for energizing the valve body 31 in a valve closing direction. The energization mechanism (51, 42) energizes the valve body 31 located from the full-open position to an intermediate position between the full-open position and the closed position, among the full-open position and the closed position.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The technology of the present disclosure relates to check valves. [Background technology]

[0002] A check valve is a mechanism that is provided in a pipe through which a fluid passes, and allows a flow in one direction but stops a flow in the opposite direction. Patent Document 1 discloses a spring-biased disc-shaped check valve having a casing with an inlet and an outlet, an annular valve seat provided between the inlet and the outlet, a disc-shaped valve body provided on the outlet side of the annular valve seat, and a spring that biases the disc-shaped valve body against the annular valve seat. In this configuration, when the pressure on the inlet side (primary side) becomes higher than the pressure on the outlet side (secondary side) and the pressure difference becomes greater than the biasing force of the spring, the valve opens to allow the fluid to flow from the inlet to the outlet. Also, when the pressure difference becomes lower than the biasing force, the valve closes, so that the fluid does not flow back from the outlet to the inlet. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 10-030743 Summary of the Invention [Problem to be solved by the invention]

[0004] In conventional check valves, the difference between the pressure on the primary side and the pressure on the secondary side must exceed at least the biasing force of the spring in order for the valve to open. However, depending on the application, there is a demand for the valve to open with an extremely small pressure difference. On the other hand, if the spring is removed to meet this requirement, the valve disc will not close even if the secondary pressure becomes higher than the primary pressure, which may result in backflow. This is because when the valve hole is wide open, the fluid can bypass the valve disc and pass through the valve hole, making it difficult for the fluid to apply pressure in the valve closing direction.

[0005] The technology disclosed herein has been made in consideration of the above circumstances, and its purpose is to provide a check valve that opens the valve body with a smaller pressure difference than conventional spring-loaded check valves and can suppress the occurrence of backflow. [Means for solving the problem]

[0006] The check valve of the present disclosure comprises a valve chamber, a casing having a valve hole formed in the valve chamber, a valve body provided in the valve chamber and displacing between a closed position at which the valve hole is closed and a fully open position at which the valve hole is fully opened to open and close the valve hole, and a biasing mechanism for biasing the valve body in a valve closing direction. The biasing mechanism biases the valve body from the fully open position to an intermediate position between the fully open position and the closed position, among the positions from the fully open position to the closed position. Effect of the Invention

[0007] The check valve described above can be opened with a smaller pressure difference than before, and can suppress the occurrence of backflow. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a vertical cross-sectional view of a check valve having a spring as a biasing mechanism when the valve element is in a closed position. [Diagram 2] 2 is a plan view showing a first member and a first holding member of a casing in the check valve of FIG. 1, as viewed from the inlet side. [Diagram 3] 3 is a cross-sectional view of the second member of the casing in the check valve of FIG. 1 taken along the line C1-C1. [Figure 4] FIG. 4 is a cross-sectional view of the check valve of FIG. 1 when the valve body is in an intermediate position. [Diagram 5] FIG. 5 is a cross-sectional view of the check valve of FIG. 1 when the valve body is in a fully open position. [Figure 6] FIG. 6 is a vertical cross-sectional view of a check valve having a magnet as a biasing mechanism when the valve disc is in a closed position. [Figure 7]FIG. 7 is a cross-sectional view of the check valve of FIG. 6 when the valve body is in an intermediate position. [Figure 8] FIG. 8 is a cross-sectional view of the check valve of FIG. 6 when the valve body is in a fully open position. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] 1. First embodiment Exemplary embodiments will now be described in detail with reference to the accompanying drawings.

[0010] (Check valve structure) Fig. 1 is a cross-sectional view of a check valve 100 in this embodiment. Fig. 2 is a plan view showing a first member 11 and a first holding member 41 of a casing 1 in the check valve 100 as viewed from the inlet 21 side. Fig. 3 is a cross-sectional view of a second member 12 of the casing 1 taken along the C1-C1 arrows.

[0011] The check valve 100 is connected to a pipe through which a fluid flows, and allows the fluid to flow from upstream to downstream while suppressing the occurrence of backflow. The check valve 100 includes a casing 1, a valve body 31, and a biasing mechanism (a second holding member 42, a spring 51). Each component will be described below.

[0012] The casing 1 has therein an inlet 21, an outlet 22, an annular valve seat 23, and a valve chamber 25. A valve hole 26 is provided in the valve chamber 25 to communicate between the inlet 21 and the valve chamber 25. The valve seat 23 is provided to surround the valve hole 26. A communication hole 27 communicates between the outlet 22 and the valve chamber 25. The axis of the valve hole 26 is illustrated as A1.

[0013] In this embodiment, the inlet 21, the valve hole 26, the valve chamber 25, the communication hole 27, and the outlet 22 are arranged in this order along the axis A1. In other words, the casing 1 is provided with flow paths (the inlet 21, the valve chamber 25, and the outlet 22) that penetrate the casing 1 on the axis A1.

[0014] Specifically, the casing 1 has a first member 11 and a second member 12 connected in the axial direction A1. The first member 11 and the second member 12 are engaged with each other and fixed to each other by a male thread structure formed on the outer surface of the first member 11 and a female thread structure formed on the inner surface of the second member 12.

[0015] More specifically, the first member 11 has a valve hole 26 opening at one end and an annular valve seat 23 surrounding the valve hole 26, and has an inlet 21 opening at the other end. The first member 11 is disposed so that the end where the valve hole 26 is provided faces the second member 12. The second member 12 has an outlet 22 opening at one end and is connected to the first member 11 at the other end. The valve chamber 25 is a space surrounded by the first member 11 and the second member 12, and its upstream wall surface is formed by the first member 11, and its downstream wall surface and side wall surface are formed by the second member 12. A communication hole 27 is formed in the downstream wall surface of the valve chamber 25.

[0016] The valve element 31 is a disk-shaped member coaxial with the axis A1, and has a first surface 311 and a second surface 312 perpendicular to the axis A1. The valve element 31 opens and closes the valve hole 26 by displacing in the axial A1 direction within the valve chamber 25 and seating on and off the valve seat 23. Specifically, the valve element 31 can be displaced between a closed position where the valve hole 26 is closed, and a fully open position where the valve hole is fully open. The fully open position is a position where the valve element 31 abuts against a protrusion 6 described below.

[0017] The first shaft 32 and the second shaft 33 are cylindrical members extending in the axial A1 direction from the centers of the first surface 311 and the second surface 312 of the valve body 31, respectively. In this embodiment, the first shaft 32 and the second shaft 33 are molded integrally with the valve body 31.

[0018] The check valve 100 further includes a first holding member 41 and a second holding member 42 that respectively hold the first shaft 32 and the second shaft 33 so as to be movable in the axial direction A1. The first holding member 41 is provided within the inlet 21, and the second holding member 42 is provided within the outlet 22.

[0019] 2, the first holding member 41 is a long and thin plate-like member that crosses the valve hole 26 (and the inlet 21) in the radial direction. The first holding member 41 has a through hole 44 that holds the first shaft 32, and the through hole 44 is provided on the axis A1. The diameter of the through hole 44 is larger than the diameter of the first shaft 32. In other words, a clearance is provided between the through hole 44 and the first shaft 32.

[0020] 3, the second holding member 42 is a long and thin plate-like member that crosses the outlet 22 in the radial direction. The second holding member 42 has a through hole 45 that holds the second shaft 33, and the through hole 45 is provided on the axis A1. The diameter of the through hole 45 is larger than the outer diameter of the second shaft 33. In other words, a clearance is provided between the through hole 45 and the second shaft 33.

[0021] With the above-described configuration, the valve body 31 is held by the first holding member 41, the first shaft 32, the second holding member 42 and the second shaft 33 so as to be movable within the valve chamber 25 in the direction of the axis A1.

[0022] The biasing mechanism biases the valve body 31 in the valve closing direction. The biasing mechanism includes a spring 51 and a second holding member . The spring 51 is an example of an elastic member that applies a biasing force to the valve body 31 by elastic force and is provided on the downstream side (also in the valve opening direction) of the valve body 31. Specifically, the spring 51 is a coil spring provided on the outer periphery of the second shaft 33 between the valve body 31 and the second holding member 42.

[0023] Particularly in this embodiment, the spring 51 is not fixed to other members. Furthermore, the inner diameter of the spring 51 is set to be larger than the outer diameter of the second shaft 33. In other words, a clearance is provided between the spring 51 and the second shaft 33. This configuration allows the spring 51 to move relative to the second shaft 33 in the axial A1 direction.

[0024] The natural length of the spring 51 is set to be shorter than the distance between the closed position of the valve body 31 and the second holding member 42, and longer than the distance between the fully open position of the valve body 31 and the second holding member 42. In this embodiment, the position of the valve body 31 when the distance between the valve body 31 and the second holding member 42 coincides with the natural length of the spring 51 is called the intermediate position. When the valve body 31 is between the intermediate position and the fully open position, between the fully open position and the closed position, the spring 51 is compressed between the valve body 31 and the second holding member 42, and the spring 51 urges the valve body 31 in the valve closing direction by its elastic force. On the other hand, when the valve body 31 is farther away from the second holding member 42 than the intermediate position, the spring 51 is in a static state in which it does not contact either the valve body 31 or the second holding member 42, and therefore no urging force is applied to the valve body 31.

[0025] The second holding member 42 also functions as a support portion that supports the spring 51 from the downstream side by supporting the spring 51 described below around the through hole 45. The through hole 45 in the second holding member 42 is set smaller than the inner diameter of the spring 51, and the width of the second holding member 42 around the through hole 45 is set larger than the outer diameter of the spring 51. Furthermore, since the position of the spring 51 can change in the radial direction of the second shaft 33 by the difference between the inner diameter and the diameter of the second shaft 33, it is preferable that the width of the second holding member 42 is set wide enough to support the entire end of the spring 51, including this change.

[0026] The check valve 100 further includes a protrusion 6 formed on the downstream wall surface of the valve chamber 25. The protrusion 6 functions as a limiting member that limits the movement range of the valve element 31 in the valve opening direction. In this embodiment, a plurality of protrusions 6 are formed radially at intervals to surround the communication hole 27. In other words, grooves 61 (recesses between the protrusions 6) are formed radially around the communication hole 27 on the inner surface of the valve chamber 25 (FIG. 3). When the valve element 31 abuts against the protrusion 6, that is, when the valve element 31 is in the fully open position, the grooves 61 ensure a flow path from the valve chamber 25 to the communication hole 27, so that the fluid can flow from the inlet 21 to the outlet 22.

[0027] (Check valve operation) The operation of the check valve 100 will now be described with reference to FIGS.

[0028] Check valve 100 is attached to a pipe so that inlet 21 faces upstream and outlet 22 faces downstream. The upstream side of check valve 100 is called the primary side, and the downstream side is called the secondary side, with the pressure on the primary side called P1 and the pressure on the secondary side called P2.

[0029] As described above, the valve element 31 moves on the axis A1 between a closed position where the valve hole 26 is closed, and a fully open position where the valve hole 26 is fully opened. Specifically, the closed position is a position where the valve element 31 sits on the valve seat 23 (FIG. 1), and the fully open position is a position where the valve element 31 is farthest from the valve seat 23 within its movable range, that is, a position where the valve element 31 contacts the protrusion 6 (FIG. 5). It can be said that the greater the distance of the valve element 31 from the valve seat 23, the greater the opening degree.

[0030] As described above, the intermediate position is the position of the valve body 31 between the closed position and the fully open position when the distance between the valve body 31 and the second holding member 42 coincides with the natural length of the spring 51 (FIG. 4). In other words, the intermediate position is the boundary between the area where the valve body 31 receives the biasing force of the spring 51 and the area where it does not receive it, and in the intermediate position, the spring 51 reaches its natural length with both ends of the spring 51 in contact with the valve body 31 and the second holding member 42, respectively. The area from the closed position to just before the intermediate position is called the "free area," and the area from the intermediate position to the fully open position is called the "biased area."

[0031] Hereinafter, movement in the valve opening direction will be referred to as "retraction" and movement in the valve closing direction will be referred to as "advancement."

[0032] When the valve element 31 is in the closed position and the difference between the secondary pressure P2 and the primary pressure P1 (P1-P2) is less than 0, i.e., does not reach a value at which the valve element 31 can be moved (hereinafter, this pressure difference will be referred to as the "minimum valve opening pressure difference Pi"), the valve element 31 remains in the closed position (Figure 1).

[0033] When the pressure difference (P1-P2) increases and reaches the minimum valve opening pressure difference Pi, the valve element 31 moves back. In other words, the valve element 31 leaves the valve seat 23, and the valve hole 26 is opened. The fluid flows from the opened inlet 21 through the valve hole 26 into the valve chamber 25, and then flows through the communication hole 27 and the outlet 22 to the outside of the casing 1.

[0034] While the valve element 31 is in the free region, if the pressure difference (P1-P2) becomes negative and becomes small enough to allow the valve element 31 to advance, the valve element 31 advances and finally seats, closing the valve hole 26. At this time, the spring 51 does not contact at least either the valve element 31 or the second holding member 42, and therefore does not bias the valve element 31.

[0035] On the other hand, when the valve body 31 retreats to the biasing region (FIG. 4) and the distance between the valve body 31 and the second holding member 42 becomes shorter than the natural length of the spring 51, the spring 51 comes into contact with both the valve body 31 and the second holding member 42 and is compressed. As a result, the valve body 31 is biased in the valve closing direction by the elastic force of the spring 51.

[0036] When the pressure difference (P1-P2) exceeds the biasing force of the spring 51, the valve element 31 moves back to the fully open position at most (FIG. 5). Even if the valve element 31 moves back to the fully open position, the groove 61 ensures a flow path from the valve chamber 25 to the communication hole 27, so the fluid can pass through the casing 1 from the inlet 21 to the outlet 22.

[0037] When the valve element 31 is in the biased region and the pressure difference (P1-P2) falls below the biasing force of the spring 51, the valve element 31 advances due to the biasing force of the spring 51. When the valve element 31 advances to the free region due to the biasing force of the spring 51, the valve element 31 either remains seated or displaces in the same manner as in the above-mentioned operation in the free region, depending on the relationship between the biasing force and the pressure difference.

[0038] In the case of a conventional biasing mechanism that constantly biases the valve body regardless of its position, the biasing force must at least exceed the biasing force in order to open the valve.

[0039] In contrast, in this embodiment, while the valve element 31 is in the free region, in other words, while the opening degree is small, the spring 51 is not compressed, and therefore the valve element 31 is not subjected to a biasing force. In other words, according to this embodiment, the valve can be opened with a very small pressure difference.

[0040] On the other hand, if the check valve does not have any biasing mechanism, the valve may remain open and backflow may occur even if the pressure difference (P1-P2) is significantly negative. This is because the fluid flows from the outlet to the inlet, bypassing the valve body, making it difficult for the valve body to be subjected to a force in the closing direction. In particular, as the opening becomes larger, the bypass flow rate also increases, making backflow more likely to occur.

[0041] In contrast, in this embodiment, the biasing force of the spring 51 works while the valve element 31 is in the biasing region, in other words, when the opening degree becomes large to a certain extent. Therefore, it is possible to at least suppress the above-mentioned detouring and to reduce the opening degree to a degree where the secondary fluid pressure in the valve closing direction is applied to the valve element 31. As a result, it is possible to suppress the occurrence of backflow from the outlet 22 to the inlet 21.

[0042] As described above, the check valve 100 of this embodiment includes a casing 1 having a valve chamber 25 and a valve hole 26 formed in the valve chamber 25. The check valve 100 further includes a valve element 31 provided in the valve chamber 25, and the valve element 31 opens and closes the valve hole 26 by displacing between a closed position at which the valve hole 26 is closed and a fully open position at which the valve hole 26 is fully opened. The biasing mechanism (spring 51 and second holding member 42) biases the valve element 31 in the valve closing direction. However, the biasing mechanism (spring 51 and second holding member 42) is provided so as to bias the valve element 31 when the valve element 31 is located from the fully open position to an intermediate position between the fully open position and the closed position, among the positions from the fully open position to the closed position.

[0043] As a result, the valve element 31 between the closed position and just before the intermediate position is not biased by the biasing mechanism (spring 51 and second holding member 42), so the check valve 100 can open with a very small pressure difference between the primary side and the secondary side. Also, the valve element 31 between the intermediate position and the fully open position is biased in the valve closing direction by the biasing mechanism (spring 51 and second holding member 42), so the check valve 100 closes when the pressure on the secondary side becomes higher than the primary side, and the occurrence of backflow from the secondary side to the primary side can be suppressed.

[0044] The biasing mechanism also has a spring 51, which is an elastic member provided downstream of the valve body 31, and a second holding member 42, which is a support portion that supports the spring 51. The spring 51 and the second holding member 42 bias the valve body 31 by the elastic force of the spring 51, and are provided so that the spring 51 material has a natural length when the valve body 31 is displaced to the intermediate position. This allows the spring 51 to bias the valve body 31 when it is in the fully open position to the intermediate position.

[0045] The check valve 100 also has a second shaft 33, which is an example of a shaft that is disposed downstream of the valve body 31 and is connected to the valve body 31. The second shaft 33 extends in the displacement direction of the valve body. The check valve 100 also includes a second holding member 42 that holds the second shaft 33 movably in the displacement direction of the valve body 31 (the direction of axis A1 in the first embodiment). Since the above-mentioned spring 51 is a coil spring provided on the outer periphery of the second shaft 33, the biasing force of the spring 51 in the valve closing direction can be reliably applied to the valve body 31.

[0046] 2. Second embodiment The biasing mechanism may be a magnet in addition to an elastic member such as a spring. A check valve that uses the repulsive force of a magnet as a biasing force will be described below.

[0047] Figures 6 to 8 are cross-sectional views of the check valve 101 of this embodiment, with the valve element 31 in the closed position in Figure 6, the valve element 31 in the intermediate position in Figure 7, and the valve element 31 in the fully open position in Figure 8. Members already explained are given the same reference numerals and their explanation will be omitted.

[0048] The check valve 101 includes a pair of a first magnet 52 and a second magnet 53 instead of the spring 51. The first magnet 52 and the second magnet 53 are arranged so as to bias the valve body 31 by the repulsive force between the magnets. Specifically, the first magnet 52 and the second magnet 53 are annular with a through hole. The first magnet 52 and the second magnet 53 are arranged between the valve body 31 and the second holding member 42 so that the second shaft 33 passes through the through hole of each magnet. In addition, the first magnet 52 and the second magnet 53 are arranged in this order from the valve body 31 toward the second holding member 42 so that the same magnetic poles face each other.

[0049] In this embodiment, the first magnet 52 and the second magnet 53 are held by the second shaft 33 so as to be movable on the axis A1. That is, the diameter of the through holes of the first magnet 52 and the second magnet 53 is set to be larger than the diameter of the second shaft 33, thereby providing a clearance between the second shaft 33 and each magnet. In addition, the first magnet 52 and the second magnet 53 are not fixed to other members.

[0050] The second holding member 42 limits the movement in the valve opening direction (downstream direction) of the second magnet 53. The relationship between the dimensions of the second holding member 42 and each magnet (particularly the second magnet 53) also applies to the relationship between the dimensions of the second holding member 42 and the dimensions of the spring 51.

[0051] The smaller the distance (spacing) between the first magnet 52 and the second magnet 53, the greater the repulsive force between the magnets, and the greater the distance, the smaller the repulsive force. The shortest distance between the first magnet 52 and the second magnet 53 when the repulsive force between them is zero is called the "action threshold value." In the first embodiment, the intermediate position is determined by the natural length of the spring 51, whereas in this embodiment, the intermediate position is determined by the action threshold value. That is, the position of the valve body 31 is the intermediate position when the first magnet 52 contacts the valve body 31, the second magnet 53 contacts the second holding member 42, and the distance between the first magnet 52 and the second magnet 53 coincides with the action threshold value. Note that "the repulsive force is zero" means that the repulsive force between the magnets is small enough to be negligible as a biasing force.

[0052] The operation of the check valve 101 will be described. When the valve body 31 is in the free region, that is, before the intermediate position from the closed position, the repulsive force of the magnet does not act, so the valve body 31 can move in the valve opening direction with a very small pressure difference (P1-P2) as in the first embodiment (FIG. 6). Even if the valve body 31 retreats to the extent that it comes into contact with the first magnet 52, if the distance between the first magnet 52 and the second magnet 53 exceeds the action threshold, the first magnet 52 retreats together with the valve body 31 without applying an urging force to the valve body 31. If the first magnet 52 and the second magnet 53 approach each other up to the action threshold and the second magnet 53 is away from the second holding member 42, the second magnet 53 also retreats due to the repulsive force as the first magnet 52 retreats.

[0053] When the valve body 31 moves further back and reaches the intermediate position, the valve body 31 contacts the first magnet 52, the second magnet 53 contacts the second holding member 42, and the distance between the first magnet 52 and the second magnet 53 coincides with the action threshold value (FIG. 7). In other words, when the valve body 31 is in the intermediate position, the distance between the valve body 31 and the second holding member 42 is the action threshold value plus the thickness of the first magnet 52 and the second magnet 53.

[0054] Since the second holding member 42 abuts against the second magnet 53 from the downstream direction, the movement of the second magnet 53 is restricted, and when the valve body 31 moves further back from the intermediate position, the distance between the first magnet 52 and the second magnet 53 is compressed, and the valve body 31 is biased by a repulsive force. When the pressure difference (P1-P2) exceeds the biasing force, the valve body 31 moves back up to the fully open position.

[0055] When the pressure difference (P1-P2) falls below the biasing force while the valve element 31 is in the biased region, the biasing force causes the valve element 31 to move forward. The valve element 31 may remain seated or move in the same manner as in the free region described above.

[0056] As described above, the check valve 101 includes, as a biasing mechanism, a pair of magnets 52, 53 arranged on the downstream side of the valve body 31 with the same magnetic poles facing each other in the displacement direction of the valve body 31 (the direction of axis A1 in this embodiment), and the second holding member 42 which is a support part that supports the downstream one of the pair of magnets, the magnet 53. The pair of magnets 52, 53 and the second holding member 42 are arranged so that they bias the valve body 31 by the repulsive force between the magnets and the repulsive force becomes zero when the valve body 31 is displaced to the intermediate position.

[0057] With this configuration, in the check valve 101, the valve element 31 between the closed position and just before the intermediate position is not biased by the biasing mechanism (magnets 52, 53, and second holding member 42), so the check valve 100 can open with a very small pressure difference between the primary side and the secondary side. Also, the valve element 31 between the intermediate position and the fully open position is biased in the valve closing direction by the biasing mechanism (magnets 52, 53, and second holding member 42), so the check valve 101 closes when the pressure on the secondary side becomes higher than the primary side, and it is possible to suppress the occurrence of backflow from the secondary side to the primary side.

[0058] The check valve 101 includes a second shaft 33 that is disposed downstream of the valve body 31 and connected to the valve body 31, and that is a shaft extending in the displacement direction of the valve body 31 (the direction of axis A1 in this embodiment), and a second holding member 42 that is a holding portion that holds the second shaft 33 movably in the displacement direction of the valve body 31. Furthermore, the pair of magnets 52, 53 are annular with a through hole, and are disposed so that the second shaft 33 passes through the through hole of the magnets 52, 53. With this configuration, a stable repulsive force can be generated even when the magnet rotates around the shaft, and the repulsive force can be reliably applied to the valve body 31 in the valve closing direction.

[0059] 3. Other embodiments As described above, the above embodiment has been described as an example of the technology disclosed in this application. However, the technology in this disclosure is not limited to this, and can be applied to embodiments in which modifications, replacements, additions, omissions, etc. are appropriately performed. In addition, it is also possible to combine the components described in the above embodiment to form a new embodiment. In addition, among the components described in the attached drawings and detailed description, not only components essential for solving the problem but also components that are not essential for solving the problem in order to exemplify the technology may be included. Therefore, the fact that these non-essential components are described in the attached drawings and detailed description should not immediately be taken to mean that these non-essential components are essential.

[0060] For example, this application also discloses the following techniques: (1) The elastic member that applies a biasing force to the valve body may be rubber or the like in addition to a spring. The spring may be a leaf spring in addition to a coil spring. (2) In the first embodiment, the spring 51, which is an elastic member, is not fixed to another member and can move on the axis A1 relative to the second shaft 33. However, the present invention is not limited to this, and one end of the elastic member may be fixed to the valve body and the other end may be free, or one end may be free and the other end may be fixed to a support portion. (3) In the second embodiment, a permanent magnet is used as the magnet, but an electromagnet may be used instead. The electromagnet may be constantly energized while the check valve is in use, or may be energized to detect the opening of the check valve and generate a repulsive force when the opening reaches a certain level. (4) In the second embodiment, none of the magnets are fixed to other members and are movable on the axis A1 relative to the second shaft 33. However, the magnets may be fixed to the valve body or the support. For example, in a check valve having a configuration similar to that of the second embodiment, the first magnet 52 may be fixed to the valve body 31, the second magnet 53 may be fixed to the second holding member 42, or both the first magnet 52 and the second magnet 53 may be held by the valve body 31 and the second holding member 42, respectively. (5) In the first and second embodiments, one member (second holding member 42) functions as both a support portion that supports the elastic member and the magnet, and a holding portion that holds the shaft. This configuration can reduce the number of components and simplify the structure of the check valve. However, the present invention is not limited to this, and the support portion and the holding portion may be provided separately. (6) In the first and second embodiments, the mechanism for displaceably holding the valve body is exemplified by the second shaft 33 connected to the valve body 31 and the second holding member 42 for movably holding the second shaft 33. However, other structures such as a rail may also be used as such a mechanism. (7) In the first and second embodiments, the shafts 32, 33 are formed integrally with the valve body. However, a shaft formed separately from the valve body may be attached to the valve body. (8) In addition, in the first and second embodiments, a long, thin plate-like member having a through hole (first retaining member 41 and second retaining member 42) is exemplified as a member that holds the valve body 31 via the shafts 32, 33. However, other structural structures can be adopted as long as a flow path within the casing can be secured. (9) In the first and second embodiments, the radially arranged convex portions 6 are an example of a limiting member that limits the displacement of the valve body in the valve opening direction to the fully open position, and the shape of the limiting member is not limited to this. (10) The absolute values ​​of the distances from the closed position to the intermediate position and from the intermediate position to the fully open position, and the ratio of these distances can be changed depending on the application of the check valve, the usage environment, the required characteristics, and conditions such as the biasing force of the biasing mechanism. If the biasing mechanism has an elastic member, the intermediate position is determined by the natural length of the elastic member and the position of the support part. If the biasing mechanism has a magnet, the intermediate position can be adjusted by the action threshold of the magnet and the position of the support part. (11) The casing may have any structure as long as it has a valve chamber and a valve hole, and is not limited to the structures of the first and second embodiments described above. (12) Any combination of the above-mentioned embodiments is also included in the disclosure of this application. [Industrial Applicability]

[0061] As described above, the technology of the present disclosure is useful for check valves. [Explanation of symbols]

[0062] 100 Check valve 1 Casing 11 First member 12 Second member 23 Valve seat 25 Valve chamber 26 Valve hole 27 Communication hole 31 Valve body 311 First surface of valve body 312 Second surface of valve body 32 First Shaft 33 Second Shaft 21 Inlet 22 Outlet 41 First holding member 42 Second holding member (holding portion, support portion) 44, 45 Through holes 46 Support part 51 Spring (elastic member) 52 First Magnet 53 Second Magnet 6 Convex 61 Groove

Claims

1. a casing having a valve chamber and a valve hole formed in the valve chamber; a valve body provided in the valve chamber, the valve body opening and closing the valve hole by being displaced between a closing position at which the valve hole is closed and a fully open position at which the valve hole is fully opened; A biasing mechanism biases the valve body in a valve closing direction, The check valve, wherein the biasing mechanism biases the valve body at a position between the fully open position and an intermediate position between the fully open position and the closed position, among the positions from the fully open position to the closed position.

2. 2. The check valve according to claim 1, The check valve is characterized in that the biasing mechanism has an elastic member provided downstream of the valve body and a support portion that supports the elastic member, and biases the valve body by the elastic force of the elastic member, and is set so that the elastic member has its natural length when the valve body is displaced to the intermediate position.

3. The check valve according to claim 2, a shaft disposed downstream of the valve body and connected to the valve body, the shaft extending in a displacement direction of the valve body, and a holding portion holding the shaft so as to be movable in the displacement direction of the valve body, A check valve characterized in that the elastic member is a coil spring provided on the outer periphery of the shaft.

4. 2. The check valve according to claim 1, the biasing mechanism includes a pair of magnets arranged downstream of the valve body such that the same magnetic poles face each other in a displacement direction of the valve body, and a support portion that supports the downstream magnet of the pair of magnets, The pair of magnets bias the valve body by a repulsive force between the pair of magnets, and the repulsive force is positioned so as to become zero when the valve body is displaced to the intermediate position.

5. The check valve according to claim 4, a shaft disposed downstream of the valve body and connected to the valve body, the shaft extending in a displacement direction of the valve body, and a holding portion holding the shaft so as to be movable in the displacement direction of the valve body, A check valve characterized in that the pair of magnets are annular with a through hole, and the shaft is arranged to pass through the through hole.

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