Excess flow valve

Abstract

To provide an excess flow prevention valve which prevents the flow-out of an excess fluid having a normal flow rate or higher to a secondary side by being valve-closed while avoiding an error operation, also surely prevents external leakage by sufficiently maintaining sealing performance even if a temperature change occurs at the fluid, and is easily manufactured due to a simple internal constitution.SOLUTION: A body main body 10 in which a tubular body member 1 and a cap member 2 are joined to each other, and which comprises a fluid flow passage 11 therein is constituted. An accommodation space S is formed in the vicinity of an opposing face of the body main body, first and second valve bodies 5, 6 which are resiliently energized in a valve opening direction by a spring member 4 are attached to primary / secondary sides of a holder member so as to be valve-closable by fluid pressure, the accommodation space is formed of an annular step part 21 which is diameter-expanded to one side or both sides of opposing faces of the cap member and the body member, and the holder member is fit and positioned in the annular step part. The first and second valve bodies are serially attached to the primary / secondary sides, and the second valve body is loosely fit to an attachment part 14 in which the secondary side of the second valve body is formed at the primary side of the fluid flow passage.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an excess flow prevention valve that blocks a flow path to prevent excessive fluid from flowing to the secondary side when the flow rate attempts to exceed the normal flow rate due to damage to equipment connected to the secondary side, etc. [Background technology]

[0002] For example, in the hydrogen supply piping equipment of a hydrogen station for automobile fuel cells, many devices are connected through valves such as manual valves and automatic valves, and piping, and the high-pressure hydrogen is supplied to the vehicle's on-board tank from the filling nozzle on the discharge side after passing through these. In such equipment through which high-pressure hydrogen (high-pressure fluid) flows, even if only a small part of the equipment, valves, piping, etc. is damaged or broken, there is a risk of excessive leakage of the high-pressure fluid from the secondary side, so in order to prevent the fluid from flowing excessively to the secondary side beyond normal use, an excess flow prevention valve that blocks the fluid is generally connected in the flow path.

[0003] As an example of this type of excess flow valve, an excess flow valve is disclosed in Patent Document 1. In this excess flow valve, a second tubular member is screwed into a first tubular member having a valve chamber, and a valve element is movably attached in the valve chamber along the flow path direction. Such an excess flow valve is formed in a substantially tubular shape and connected in series to the flow path. Under normal conditions, the valve is kept open and a normal flow rate flows, but when the flow rate becomes extremely larger than the normal flow rate due to damage to equipment or piping, the valve element moves to the secondary side and closes the valve, blocking the flow path. This valve has a so-called single-stage structure in which a single valve element is attached in the main body, and the flow path is closed by the operation of this single-stage valve element.

[0004] In contrast, as shown in FIG. 6(a), a so-called two-stage excess flow valve 100 in which two valve bodies are mounted in the main body is also known. This excess flow valve 100 includes a tubular body 101 and a cap 102. A cylindrical portion 103 is formed on the front side of the cap 102, and an expanded diameter cylindrical portion 104, which is larger in diameter than the cylindrical portion 103, is formed on the rear side of the cap 102. A male thread portion 105 is provided on the outer periphery of the expanded diameter cylindrical portion 104. A sealing O-ring 106 is attached to the outer periphery of the cylindrical portion 103 near the boundary with the expanded diameter cylindrical portion 104. Meanwhile, the body 101 is formed with an insertion hole portion 110 into which the cylindrical portion 103 is inserted, and a mounting recess 111 into which the expanded diameter cylindrical portion 104 is mounted, and a female thread portion 112 into which the male thread portion 105 is screwed is provided on the inner periphery of the mounting recess 111.

[0005] The cap 102 is attached to the body 101 by screwing the male threaded portion 105 and the female threaded portion 112 together, and after attachment, the cylindrical portion 103 is inserted into the insertion hole 110 and sealed with an O-ring 106, and a tip surface 104a on the tip side of the enlarged diameter cylindrical portion 104 abuts against a bottom surface 111a of the mounting recess 111 to be positioned and fixed to the body 101. A cylindrical holder 120 is housed in the insertion hole 110 on the forward side of the cylindrical portion 103, and this holder 120 is fixed in a positioned state between the cylindrical portion tip surface 103a and the abutment surface 110a of the insertion hole 110. A first poppet valve body 121 is attached to the primary side of the holder 120, and a second poppet valve body 122 is attached to the secondary side. As shown in FIG. 6(b), the first poppet valve body 121 and the second poppet valve body 122 are each arranged to be movable in the valve closing direction against the elastic force of a spring 123 attached inside. An annular elastic member 124 is attached to the tip side of the cylindrical portion 103, and this elastic member 124 is pressed against the holder 120 when the cap 102 is screwed on. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2010-266000 A Summary of the Invention [Problem to be solved by the invention]

[0007] The excessive flow prevention valve of the former Patent Document 1 has a single-stage valve disc structure. Therefore, when the fluid pressure flowing through the piping equipment to which this valve is connected suddenly increases (for example, immediately after the power is turned on), even if there is no excessive outflow above normal levels, the sudden flow can cause one of the valve discs to move in the closing direction, resulting in a malfunction that may close the flow path.

[0008] On the other hand, the latter excess flow valve 100 in Figure 6 is provided with poppet valve bodies 121, 122 of a two-stage structure. Even if the first poppet valve body 121 of the first stage malfunctions due to a sudden increase in pressure and closes the valve, a small amount of fluid continues to flow to the second poppet valve body 122 of the second stage when the valve is closed, making it possible to avoid the sudden closure of the flow path as occurs in the single-stage excess flow valve of Patent Document 1. However, since this excess flow prevention valve 100 is configured such that the outer periphery of the cylindrical portion 103 and the inner periphery of the insertion hole portion 110 are sealed in the circumferential direction by the O-ring 106 while the expanded diameter cylindrical portion 104 is screwed into the mounting recess 111, the sealing ability decreases when the O-ring 106 expands or contracts due to a change in the temperature of the fluid, etc., and particularly when a low-temperature, high-pressure fluid flows, the O-ring 106 may contract, resulting in external leakage.

[0009] Furthermore, the cap 102 is positioned and fixed to the body 101 by abutting the tip surface 104a of the enlarged diameter cylindrical portion 104 against the bottom surface 111a of the mounting recess 111, thereby defining a space C in which the holder 120 of the insertion hole 110 is housed, and the length of this space C in the flow path direction is constant. Therefore, if the elastic member 124 pressed between the holder 120 and the cylindrical portion tip surface 103a deteriorates with age or shrinks or breaks and becomes shorter in the flow path direction, an excessively large gap is generated between the cap 102 and the holder 120, and the holder 120 is not sufficiently fixed.

[0010] As described above, space C of holder 120 is set by the abutment between tip surface 104a of the enlarged cylindrical portion and bottom surface 111a of the mounting recess, so precise dimensional accuracy is required during production, and the internal structure is complex, making it difficult to process.

[0011] The present invention was developed to solve the problems of the related art, and its purpose is to provide an excess flow prevention valve which closes the valve while avoiding malfunction, prevents excess fluid above the normal flow rate from flowing to the secondary side, maintains sufficient sealing performance even when the fluid experiences a temperature change, and is easy to manufacture due to its simple internal structure. [Means for solving the problem]

[0012] In order to achieve the above object, the invention of claim 1 is an excess flow prevention valve in which a tubular body member and a cap member are joined to form a body main body having an internal fluid flow path, and an accommodation space is formed near the opposing surface of the body main body, which communicates with the fluid flow path and accommodates a cylindrical holder member, and a first valve body and a second valve body, each of which is resiliently biased in a valve opening direction by a spring member, are attached to one and secondary sides of the holder member accommodated in the accommodation space in a state in which the valve can be closed by fluid pressure, and the accommodation space is formed by an annular step portion formed on one or both of the opposing surfaces of the cap member and the body member with a larger diameter than the fluid flow path, and the outer periphery of the holder member is fitted into this annular step portion to position it, and the first valve body and the second valve body are attached in series to the primary side and secondary side, respectively, with respect to the holder member, and the secondary side of the second valve body is loosely fitted into an attachment portion formed on the primary side of the fluid flow path.

[0013] The invention according to claim 2 is an excess flow valve in which a long cylindrical portion is formed on the secondary side of the second valve body, and this long cylindrical portion is formed into an outer shape that allows it to be inserted into the mounting portion.

[0014] The invention according to claim 3 is 、 The mounting part is 、 The secondary flow passage, which is the secondary side of the fluid flow passage, is handThis is an excess flow prevention valve that is formed with an expanded diameter. Effect of the Invention

[0015] According to the invention described in claim 1, an annular step portion is formed on the opposing surfaces of the cap member and the body member, and the outer periphery of the holder member is fitted into the annular step portion to position it. Therefore, the body member and the cap member can be easily integrated through this holder member with the first valve body, the second valve body, and the spring member temporarily assembled. In addition, since an annular step portion is provided in this manner to form an accommodating space and the holder member is fixed into this accommodating space by clamping, the space required for mounting the holder member can be reduced to a minimum, thereby simplifying the structure and making it compact. An attachment portion is formed in a secondary side flow passage provided on the inner periphery of the body member, and with the second valve body loosely fitted between the holder member and the attachment portion of the body member within the secondary side flow passage, the second valve body can be brought into a valve closed state when fluid pressure is applied from the first valve body side.

[0016] According to the invention described in claim 2, by inserting the secondary side long cylindrical portion of the second valve body into the mounting portion, the second valve body can be positioned within the secondary side flow passage of the body member, between the holder member and the mounting portion of the body member.

[0017] According to the invention described in claim 3, the second valve body can be attached to the secondary side flow passage formed in the body member, and the second valve body can be abutted and sealed against the valve seat portion formed in this secondary side flow passage to bring the valve into a closed state. [Brief description of the drawings]

[0018] [Figure 1] FIG. 2 is a cross-sectional view showing an embodiment of an excess flow valve of the present invention. [Diagram 2] FIG. 2 is an exploded perspective view of the excess flow valve of FIG. 1; [Diagram 3] FIG. 2 is an enlarged cross-sectional view of a main part of FIG. [Figure 4] 4 is an enlarged cross-sectional view of a main portion showing a first valve body in FIG. 3 in a valve closed state. [Diagram 5]4 is an enlarged cross-sectional view of a main portion showing a valve-closed state of the first valve body and the second valve body in FIG. 3. [Figure 6] FIG. 1 is a cross-sectional view showing a conventional excess flow valve. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] An embodiment of the excess flow valve of the present invention will be described in detail below with reference to the drawings. The excess flow valve of the present invention is particularly suitable as an excess flow prevention valve used in hydrogen supply piping facilities at hydrogen stations. Fig. 1 shows an embodiment of the excess flow valve of the present invention in the valve open state. Fig. 2 is an isolated perspective view of the excess flow valve of Fig. 1, and Fig. 3 shows an enlarged cross-sectional view of the essential parts of the excess flow valve of Fig. 1 in the valve open state.

[0020] In the figure, the excess flow valve is comprised of a body member 1, a cap member 2, a cylindrical holder member 3, a spring member 4 consisting of a coil spring, a first valve body 5, a second valve body 6, a buffer member 7, and a sealing gasket 8, which are combined together to maintain the valve open at normal flow rates, and when the flow rate exceeds the normal flow rate, the valve closes to prevent excess flow to the secondary side. Note that in the excess flow valve in Figure 1, the left side is the primary side and the right side is the secondary side.

[0021] The body member 1 and the cap member 2 are formed into a tubular shape from, for example, stainless steel or a stainless steel alloy, and are joined together to form a main body 10, within which a fluid flow path 11 is provided.

[0022] In the main body 10, a side wall portion 10a is formed on the joint side (left side in the figure) of the body member 1 with the cap member 2, the vicinity of the outer periphery of which rises toward the primary side, and a female thread 12 is formed on the inner periphery of this side wall portion 10a. A secondary side flow passage 13 that constitutes the secondary side of the fluid flow passage 11 is formed on the inner periphery on the center side of the body member 10, and this secondary side flow passage 13 is formed with a larger diameter on the side facing the cap member 2. A mounting portion 14 that is slightly larger in diameter toward the primary side is formed in the secondary side flow passage 13, and a valve seat portion 15 is formed on the inner periphery of the primary side of this mounting portion 14. A reduced diameter abutment locking surface 16 is formed on the secondary side (right side), and one end side (right end) of the resiliently biased spring member 4 is provided to abut and lock on this abutment locking surface 16.

[0023] An opposing surface 20 is provided on the inner side of the side wall portion 10a of the body member 1 on the joining end surface side of the cap member 2, and an annular step portion 21 having a predetermined depth and a stepped portion with a larger diameter than the mounting portion 14 is formed on the inner diameter side of the opposing surface 20 near the fluid flow path 11. The annular step portion 21 is provided with a diameter slightly larger than the outer diameter of the holder member 3.

[0024] On the outer diameter side of the annular step portion 21 of the body member side opposing surface 20, an obtuse-angled edge seal portion 22 is formed so as to protrude approximately tapered in the inner diameter direction, and further on the outer diameter side of this edge seal portion 22, an enlarged-diameter annular recess 23 is formed adjacent to this edge seal portion 22.

[0025] Meanwhile, in the cap member 2, a male thread 30 that can be screwed into the female thread 12 is formed on the outer periphery of the joining side (the right side in the figure) with the body member 1. A primary side flow passage 31 that forms the primary side of the fluid flow passage 11 is formed on the inner periphery on the center side of the cap member 2, and this primary side flow passage 31 is formed with a larger diameter on the side facing the body member 1.

[0026] An opposing surface 32 is provided on the joint end surface side of the cap member 2 with the body member 1, and an annular step 33 with a step portion having a larger diameter than the fluid flow path 11 is formed on the inner diameter side of this opposing surface 32 near the fluid flow path 11, and in this example, is formed deeper in the flow path direction than the annular step 21 of the body member 1. The annular step 33 is provided at a predetermined depth with a diameter substantially the same as the outer diameter of the holder member 3, and in this embodiment, the inner diameter of the annular step 33 is formed slightly larger than the outer diameter of the holder member so as to provide a very small gap between them.

[0027] Furthermore, on the outer diameter side of the annular step portion 33 of the cap member side opposing surface 32, an obtuse-angled edge seal portion 34 is formed which protrudes approximately tapered in the inner diameter direction and has an approximately symmetrical shape to the body member side edge seal portion 22, so as to face the body member side edge seal portion 22.

[0028] The edge seal portions 22, 34 on the body member 1 side and the cap member 2 side described above may be formed, for example, with the angle α1 and the angle α2 each being an appropriate angle in the range of 160 to 178°, and in this embodiment, both the angles α1 and α2 are set at an obtuse angle of 170°.

[0029] The opposing surfaces 20 and 30 are spaced apart from each other on the outer diameter side of the edge seal portions 22 and 34, particularly on the outer diameter side of the gasket 8, and have a clearance G1. This clearance G1 allows the cap member 2 and the body member 3 to be further tightened, and allows for additional tightening when the sealing performance deteriorates.

[0030] After the body member 1 and the cap member 2 are integrated, a storage space S of a predetermined size is formed near the opposing surface of the body main body 1 by the aforementioned annular step portions 21, 33, and the holder member 3 is arranged to be able to be accommodated within this storage space S. The primary side end (cap member 2 side) of the body main body 10 is provided with a primary side joint 35 with an internal thread, and the secondary side end (body member 1 side) is provided with a secondary side joint 36 with an internal thread, and an overflow prevention valve is provided so as to be connectable to a predetermined position in the piping equipment through the primary side joint 35 and the secondary side joint 36.

[0031] The holder member 3 is formed in a size that allows it to be installed in the accommodation space S, and an annular groove 40 is formed on the outer diameter side of the holder member 3 facing the facing surface 20 of the body member 1, and the buffer member 7 is attached by fitting into this groove 40. On the side of the holder member 3 facing the facing surface 32 of the cap member 2, two V-shaped notched grooves 41 are formed at equal intervals from the center side to the outer periphery, and fluid can pass through the notched grooves 41.

[0032] A receiving portion 42 consisting of a communicating hole is formed on the inner diameter side of the notched groove 41, and a spring member 4 is provided so as to be mountable in this receiving portion 42. In the drawing, a reduced diameter abutment locking surface 43 is formed on the right side of the receiving portion 42, and one end side (right end portion) of the spring member 4 resiliently biased is provided so as to be abutted and locked against this abutment locking surface 43. A valve seat portion 44 is formed on the left open end side of the receiving portion 42, against which the first valve body 5 can abut and seal.

[0033] The cushioning member 7 is made of a fluororesin material such as PTFE, and is formed with an outer diameter and thickness that allows it to come into contact with the opposing surface of the annular step portion 21. The cushioning member 7 is accommodated in the accommodation space S in a state in which it can contract between the holder member 3 and the body member 1 in response to the force of the two members pressing against each other. The cushioning member 7 can contract in response to the joining force when the cap member 2 and the body member 1 are joined. The cushioning member 7 also has the function of fixing the holder member 3 to the main body 10.

[0034] Here, the opposing surfaces of the holder member 3 and the body member 1, which face each other via the buffer member 7, are separated by a predetermined clearance G2. This clearance G2 needs to be provided at least to be equal to or larger than the amount of fastening between the cap member 2 and the body member 1 using the clearance G1, and may be at most approximately equal to the clearance G1.

[0035] Furthermore, if the holder member 3 protrudes too far from the recessed groove 40 toward the annular step 21, excessive tightening force is required between the body member 1 and the cap member 2, whereas if the protrusion is too small, the holder member 3 cannot abut against the annular step 21 and cannot be fixed. Therefore, the protrusion amount of the buffer member 7 must be at least such that the buffer member 7 can abut against the body member 1 and the cap member 2 in the fastened state. On the other hand, it is preferable that the buffer member 7 just contacts the annular step 21 or does not contact it very much when the edge seal portion 22 and the edge seal portion 34 are in contact with the gasket 8, so that excessive tightening is not required.

[0036] A gasket 8 formed to have a diameter larger than the outer periphery of the holder member 3 is attached to the annular recess 23. The gasket 8 is made of, for example, copper or a copper alloy, and is sandwiched between the annular recess 23 and an opposing surface 32 on the cap member 3 side in a state where it is fitted into the annular recess 23. With this mounting structure, the holder member 3 has the gasket 8 attached between the opposing surfaces 20, 32 at its outer periphery, and the holder member 3 is sandwiched between the body member 1 and the cap member 2 within the storage space S so as to pass through the inner diameter side of the gasket 8.

[0037] A notched groove 41 is disposed between the holder member 3 and the cap member 2, and a communication passage T is formed near the primary side of the main body 10 by the holder member 3 and the cap member 2. In this case, the opposing surface 32 of the cap member 2 and the holder member 3 communicate in the inner and outer periphery directions through the notched groove 41, and the communication passage T is provided by a very small gap provided between the inner periphery of the cap member 2 and the outer periphery of the holder member 3, which continues from the notched groove 41. In this way, the communication passage T is provided in a range that communicates the area from the primary side of the first valve body 5 through the gap with the annular step portion 21 on the outer periphery side of the holder member 3 to the location where the buffer member 7 is attached.

[0038] A first valve body 5 and a second valve body 6, each formed in the shape of a poppet valve, are attached in series to the primary side and the secondary side, respectively, in relation to a holder member 3 housed in the accommodation space S, and these first valve body 5 and second valve body 6 form a two-stage excess flow prevention valve.

[0039] The first valve body 5 and the second valve body 6 are made of a resin material such as polyether ether ketone (PEEK) or polyimide (PI), which belong to the super engineering plastics. Enlarged diameter disk portions 50, 51 are formed in parts of them, and seal portions 52, 53 are formed on the secondary side outer periphery of these disk portions 50, 51. The seal portions 52, 53 are provided so as to be able to abut and seal against the valve seats 44, 15 described above, respectively.

[0040] In both the first valve body 5 and the second valve body 6, short cylinder portions 54, 55 are formed on the primary side of the seal portions 52, 53, and each of the short cylinder portions 54, 55 abuts on an end face 56 of the primary side flow passage and an end face 57 of the secondary side of the holder member 3 on the primary side. Each of the short cylinder portions 54, 55 is partially cut out to form a plurality of communication holes 58, 59, and fluid flows in through these communication holes 58, 59 when the short cylinder portions 54, 55 abut against the end faces 56, 57. Long cylinder portions 60, 61 are formed on the secondary side of the seal portions 52, 53 of each valve body, and a plurality of communication hole portions 62, 63 are formed on the disk portion 50, 51 side of each of the long cylinder portions 60, 61. On the secondary side of the communicating hole portions 62, 63, reduced-diameter abutment engagement surfaces 64, 65 are formed, respectively, and one end side (left end portion) of the resiliently biased spring member 4 is provided to abut and engage with each of the abutment engagement surfaces 64, 65.

[0041] The long cylinder portion 60 of the first valve body 5 is formed with an outer diameter that allows it to be inserted into the accommodation portion 42, and the long cylinder portion 61 of the second valve body 6 is formed with an outer diameter that allows it to be inserted into the attachment portion . A through hole 70 is formed in the center of the disk portion 50 of the first valve body 5, and the first valve body allows the fluid to flow to the secondary side at a reduced flow rate through this through hole 70 even when the seal portion 52 of the first valve body 5 abuts against the valve seat portion 44 (valve closed position). On the other hand, no through hole is formed in the disk portion 51 of the second valve body 6, and when this second valve body is closed, the flow of fluid to the secondary side is prevented.

[0042] In some cases, the second valve body 6 may also be configured to allow a small amount of fluid to flow out to the secondary side when in the valve closed position. Possible means for this include providing a through hole similar to that of the first valve body 5, or providing a groove in the seal portion 53 or valve seat portion 15 of the second valve body 6, and this can be set according to the amount of leakage from the second valve body 6 that is permitted even in the event of damage to the secondary side. This allows the second valve body 6 to quickly return to the valve open state after the cause of the excessive flow on the secondary side is eliminated.

[0043] The first valve body 5 is disposed in the primary flow passage 31 of the cap member 2 between the cap member 2 and the accommodation portion 42 of the holder member 3, and the secondary side of the first valve body 5 is loosely fitted in the accommodation portion 42. The spring member 4 is accommodated between the abutment locking surface 64 of the first valve body 5 and the abutment locking surface 43 of the holder member 3 in a resilient biased state, and the first valve body 5 is normally resilient-biased to the primary side (leftward in the figure) by the spring member 4 to maintain the valve open state. On the other hand, when fluid pressure is applied from the primary side, the first valve body 5 moves to the secondary side (rightward in the figure) against the resilient bias of the spring member 4, and when the fluid pressure exceeds the resilient bias of the spring member 4, the seal portion 52 abuts against the valve seat portion 44 for sealing, and the valve is closed.

[0044] The second valve body 6 is disposed between the holder member 3 and the mounting portion 14 of the body member 1 in the secondary flow passage 13 of the body member 1, and its secondary side is loosely fitted in the mounting portion 14. The spring member 4 is accommodated in a resilient engagement state between the abutment and locking surface 65 of the second valve body 6 and the abutment and locking surface 16 of the body member 1, and in the same manner as the first valve body 5, the second valve body 6 is normally resilient-biased to the primary side (leftward in the figure) by the spring member 4 to maintain the valve open state. On the other hand, when fluid pressure is applied from the first valve body 5 side, the second valve body 6 moves to the secondary side (rightward in the figure) against the resilient bias of the spring member 4, and when the fluid pressure exceeds the resilient bias of the spring member 4, the seal portion 53 abuts against the valve seat portion 15 for sealing, and the valve is closed.

[0045] In this case, assuming that the resilient force applied to the first valve body 5 by the spring member 4 is FA and that the resilient force applied to the second valve body by the spring member 4 is FB, they are set so that the resilient force FA<the resilient force FB. This enables a two-stage operation in which the first valve body 5 first operates and then the second valve body 6 operates according to the pressure difference between the primary side and secondary side of the main body 10 centered on the holder member 3.

[0046] In the above embodiment, the buffer member 7 is attached to the side of the holder member 3 opposite the opposing surface 20 of the body member 1. However, this buffer member 7 only needs to be attached to the side opposite the opposing surface 20, 32 of at least one of the body member 1 or the cap member 2, and may be provided so as to face the opposing surfaces 20, 32 of both the body member 1 and the cap member 2.

[0047] Also, the buffer member 7 may be fixed by providing a groove in the body member 1 or the cap member 2, instead of providing a groove in the holder member 3, or may simply be sandwiched between them. Furthermore, the buffer member does not necessarily have to be annular, and may be, for example, divided into a plurality of members.

[0048] In addition, the holder member 3 is positioned by being fitted into the annular steps 33, 21 provided on both the cap member 2 and the body member 1, but it is also possible to form an annular step on either one of the opposing surfaces of the cap member 2 and the body member 1, and to fit the outer periphery of the holder member 3 into this annular step to position it.

[0049] The notch groove 41 of the holder member 3 may be formed in one place or in three or more places, and even when formed in three or more places, it is preferable that the notch groove 41 is formed radially at equal intervals from the center side to the outer periphery side. The notch groove 41 may be provided in a cross-sectional shape other than a V-shape, and for example, a notch groove having a rectangular cross-sectional shape may be formed.

[0050] When assembling the above-mentioned excess flow valve, the body member 1 is placed so that the surface 20 facing the cap member 2 faces upward, the secondary-side spring member 4 and second valve body 6 are attached to the secondary-side flow passage 13 of this body member 20, the holder member 3 is placed on the second valve body 6 with its outer diameter side facing the central portion thereof on the annular step portion 21, the primary-side spring member 4 is placed in the accommodation portion 42 of this holder member 3, and the long cylinder portion 60 of the first valve body 5 is attached so as to be inserted into the accommodation portion 42 from above. At the same time, the gasket 8 is attached by fitting it into the annular recess 23 of the body member 1.

[0051] In this state, the female thread 12 and the male thread 30 are screwed together to join the body member 1 and the cap member 2. As a result, the holder member 3 is positioned within the accommodation space S, and the first valve body 5 is attached to the primary side of the holder member 3, and the second valve body 5 is attached to the secondary side, each of which is elastically biased by the spring member 4.

[0052] After the main body 10 is constructed, the body member 1 and the cap member 2 are sealed by the gasket 8. At this time, the gasket 8 is sandwiched between the obtuse-angled edge seal portions 22, 34, and the narrow sealing surfaces of these increase the sandwiching pressure, improving the sealing performance.

[0053] Next, the operation and function of the excess flow valve of the present invention in the above embodiment will be described. 1 and 3 show a state in which the first valve body 5 and the second valve body 6 are each resiliently biased leftward by the spring member 4, with the end faces 56, 57 of each valve body 5, 6 abutting against the opposing abutment faces of the cap member 2 and the holder member 3. In this case, the communication port 58, the communication hole portion 62, and the through hole 70 of the first valve body 5, and the communication port 59 and the communication hole portion 63 of the second valve body are respectively communicated with the primary flow path 31 and the secondary flow path 13, and the valve open state is maintained.

[0054] As a result, when high-pressure hydrogen (high-pressure fluid) flows in at a normal flow rate from the left in the figure, this fluid flows into the holder member 3 through the communication port 58 and communication hole portion 62 on the cap member 2 side, and then this fluid flows to the secondary side through the communication port 59 and communication hole portion 63 on the body member 1 side, and the fluid at the normal flow rate flows out. At this time, the communication ports 58, 59 and the communication holes 62, 63 have an opening area sufficient to allow the normal flow rate to flow, preventing the occurrence of a pressure difference between the primary side and the secondary side.

[0055] If damage occurs to equipment, valves, or piping (not shown) on the secondary side of the excess flow check valve and the secondary flow rate becomes much higher than the normal flow rate, the fluid will not be able to flow through the opening area (nozzle area) and a pressure difference will occur between the primary and secondary sides.

[0056] When this pressure difference increases, due to the relationship of elastic force FA applied to the first valve body 5<elastic force FB applied to the second valve body, as shown in Fig. 4, first the first valve body 5, which has a smaller resistance against the fluid flow direction, moves to the right in the figure, and the seal portion 52 seats on the valve seat portion 44, resulting in a valve closed state. At this time, since the through hole 70 maintains a state in which it communicates with the accommodation portion 42 of the holder member 3, the fluid continues to flow from the primary side to the secondary side through the through hole 70 at a constant flow rate that is smaller than the normal flow rate. As a result, the through hole 70 becomes an orifice, narrowing the flow rate and reducing the fluid pressure on the primary side and secondary side.

[0057] Furthermore, when the secondary flow rate of the excess flow valve increases, the pressure in the secondary flow path 13 also increases accordingly. However, the amount of fluid supplied from the primary flow path 31 cannot keep up with the recovery of the pressure in the secondary flow path 13, and the pressure difference between these two causes the second valve body 6 to move to the right as shown in Figure 5, and its seal portion 53 seats on the valve seat portion 15, closing the valve and blocking the flow path.

[0058] In this way, the excessive flow prevention valve has a two-stage structure consisting of the first valve body 5 and the second valve body 6, and the first valve body 5 operates first, and then the second valve body 5 operates. Therefore, when excessive outflow occurs on the secondary side, each valve body 5, 6 operates to reliably close the flow path while preventing damage or failure. On the other hand, when a temporary sudden flow other than the excessive flow on the secondary side occurs, such as a flow immediately after power is turned on, the first valve body 5 closes the valve while maintaining a predetermined flow rate, preventing the valve from being completely closed and preventing the entire excessive flow prevention valve from malfunctioning. Also, since the valve does not close completely, the first valve body 5 quickly returns to the valve open state when the temporary sudden flow is eliminated.

[0059] The buffer member 7 is attached to the holder member 3 with the buffer member 7 facing the opposing surface 20, and the holder member 3 is sandwiched within the accommodation space S through a gasket 8 made of copper or a copper alloy that is attached at its outer periphery between the body member 1 and the cap member 2, thereby sandwiching the gasket 8 between the body member 1 and the cap member 2 in the flow path direction to seal. Therefore, even if a temperature difference occurs in the high-pressure fluid, for example, when a low-temperature fluid flows, the gasket 8 can be prevented from expanding or shrinking, while maintaining a sufficient sealing performance due to the pressure contact force in the sandwiching direction, and external leakage can be reliably prevented.

[0060] Furthermore, by disposing the buffer member 7 between the holder member 3 and the body member 1, the tightening force between the body member 1 and the cap member 2 can be adjusted through the elastic force of this buffer member 7, and the body main body 10 can be assembled while exerting optimal sealing performance by the gasket 8, and the sealing performance can also be restored by further tightening.

[0061] The buffer member 7 can prevent an excessively large gap between the holder member 3 and the accommodation space S, and can also prevent chattering of the holder member 3 caused by fluid.

[0062] Annular steps 33, 21 are formed on both opposing surfaces 32, 20 of the cap member 2 and the body member 1, and the outer periphery of the holder member 3 is fitted and positioned between these annular steps 33, 21. Therefore, the body member 1 and the cap member 2 can be easily integrated through the holder member 3 in a temporarily assembled state with the first valve body 5, the second valve body 6 and the spring member 4. After assembly, a gasket 8 is positioned on the outer periphery of the holder member 3, and this gasket 8 reliably prevents fluid leakage from the mounting side of the holder member 3. Furthermore, by providing the annular steps 33, 21 in this manner to form the storage space S, and by fixing the holder member 3 in this storage space S by clamping, the space required to attach the holder member 3 can be reduced to a minimum, thereby simplifying the structure and making it compact.

[0063] A communication passage T is formed in the main body 1, and this communication passage T connects the area from the primary side of the first valve body 5 through the outer periphery of the holder member 3 to the buffer member 7, so that in either the open or closed state of the first valve body 5, pressure is equalized from the primary side flow path 31 to the buffer member 7 through the communication passage T, preventing the application of excessive fluid pressure to the buffer member 7. Moreover, the communication passage T is always maintained by the V-shaped cutout groove 41 provided in the holder member 3 and the very small gap between the annular step portion 21 and the outer periphery of the holder member 3.

[0064] In addition, a gap may be provided between the buffer member 7 and the annular step portion 21 on the body member 1 side, and the flow path from the first valve body 5 side, the holder member 3 side to the second valve body 6 side does not need to be completely sealed as long as the structure is such that the secondary side flow path 13 can be blocked when the second valve body 6 is closed.

[0065] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the invention as described in the claims of the present invention. [Explanation of symbols]

[0066] 1 Body parts 2 Cap member 3 Holder parts 4 Spring member 5 First valve body 6 Second valve body 7. Cushioning materials 8 Gasket 10 Body 11 Fluid flow path 20, 32 Opposite faces 21, 33 Annular step S Storage space T communication path

Claims

1. an overflow prevention valve comprising: a tubular body member and a cap member joined to form a body main body having an internal fluid flow path; a storage space formed near an opposing surface of the body main body, the storage space communicating with the fluid flow path and housing a cylindrical holder member; a first valve body and a second valve body resiliently biased in a valve opening direction by spring members, respectively, are mounted on one and secondary sides of the holder member housed in the storage space in a state in which the valves can be closed by fluid pressure; the storage space is formed by an annular step portion formed on one or both of the opposing surfaces of the cap member and the body member with a larger diameter than the fluid flow path, and the outer periphery of the holder member is fitted into the annular step portion to position it; the first valve body and the second valve body are mounted in series on the primary side and secondary side, respectively, of the holder member, and the secondary side of the second valve body is loosely fitted into a mounting portion formed on the primary side of the fluid flow path.

2. 2. The excess flow valve according to claim 1, wherein a long cylindrical portion is formed on a secondary side of the second valve body, the long cylindrical portion being formed with an outer diameter capable of being inserted into the mounting portion.

3. 3. The excess flow prevention valve according to claim 1, wherein the mounting portion is formed in a secondary flow passage that constitutes a secondary side of the fluid flow passage, and the mounting portion is formed so as to expand in diameter toward the primary side.

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