JP7620133B2 - Excess flow valve - Google Patents

Description

The present invention relates to an excess flow prevention valve that blocks the flow path and prevents excessive fluid from flowing to the secondary side when the flow rate exceeds the normal flow rate due to damage to equipment connected to the secondary side, etc.

For example, in the hydrogen supply piping equipment of a hydrogen station for automobile fuel cells, numerous devices are connected via valves such as manual valves and automatic valves, and piping, and the high-pressure hydrogen passes through these before being supplied to the automobile's on-board tank from the filling nozzle on the discharge side. 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 high-pressure fluid from the secondary side. Therefore, in order to prevent excessive flow of fluid to the secondary side beyond normal use, an excess flow prevention valve that blocks the fluid is generally connected in the flow path.

For example, an excess flow valve of this type 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 inside the valve chamber along the flow path direction. Such excess flow valves are formed in a generally tubular shape and connected in series to the flow path. Under normal circumstances, the valve remains open and the normal flow rate flows, but if the flow rate becomes extremely higher 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 single valve element attached inside the main body, and the flow path is closed by the operation of this single valve element, making it a so-called single-stage structure.

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

The cap 102 is attached to the body 101 by screwing the male threaded portion 105 into the female threaded portion 112, 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 forward 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 able to move 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 when the cap 102 is screwed, this elastic member 124 is pressed against the holder 120.

JP 2010-266000 A

The excessive flow prevention valve in Patent Document 1 has a single-stage valve body. Therefore, when the pressure of the fluid 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 bodies to move in the closing direction, resulting in a malfunction that can close the flow path.

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, so that 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 with the single-stage excess flow valve of Patent Document 1.
However, since this overflow prevention valve 100 is configured such that the O-ring 106 circumferentially seals the outer periphery of the cylindrical portion 103 and the inner periphery of the insertion hole portion 110 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, for example, a change in the temperature of the fluid, and particularly when a low-temperature, high-pressure fluid flows, the O-ring 106 may contract, resulting in external leakage.

The cap 102 is positioned and fixed to the body 101 by abutting the tip surface 104a of the enlarged 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 over time or shrinks or breaks and becomes shorter in the flow path direction, an excessive gap will be created between the cap 102 and the holder 120, and the holder 120 will not be fixed properly.

As described above, the space C of the holder 120 is set by the contact between the tip surface 104a of the enlarged cylindrical portion and the 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.

The present invention was developed to solve the problems of the past, and its purpose is to provide an excess flow prevention valve that 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 temperature changes, and reliably prevents external leakage, and has a simple internal structure that makes it easy to manufacture.

In order to achieve the above object, the invention according to 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 with a fluid flow path inside, a storage space is formed near the opposing surface of the body main body, which communicates with the fluid flow path and stores a cylindrical holder member, and a first valve body and a second valve body, each of which is resiliently biased in the valve opening direction by a spring member, are attached to one and the secondary side of the holder member stored in the storage space in a state in which the valve can be closed by the pressure of the fluid, and 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 this annular step portion to be positioned, and the first valve body and the second valve body are attached in series to the primary side and secondary side, respectively, relative to the holder member, and the secondary side of the second valve body is loosely fitted into the mounting portion formed on the primary side of the fluid flow path.

The invention according to claim 2 is an excess flow prevention 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 with an outer shape that allows it to be inserted into the mounting portion.

The invention according to claim 3 is an excess flow prevention valve in which the mounting portion is formed in a secondary flow passage that constitutes the secondary side of the fluid flow passage and is expanded in diameter toward the primary side.

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.

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 between the holder member and the mounting portion of the body member in the secondary side flow passage of the body member.

According to the invention described in claim 3, the second valve body can be attached to the secondary 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 flow passage to close the valve.

FIG. 2 is a cross-sectional view showing an embodiment of an excess flow valve of the present invention. FIG. 2 is an exploded perspective view of the excess flow valve of FIG. 1; FIG. 2 is an enlarged cross-sectional view of a main portion of FIG. 1 . FIG. 4 is an enlarged cross-sectional view of a main portion showing a valve-closed state of the first valve body of FIG. 3 . FIG. 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 of FIG. 3 . FIG. 1 is a cross-sectional view showing a conventional excess flow valve.

Below, an embodiment of the excess flow prevention valve of the present invention will be described in detail with reference to the drawings. The excess flow prevention valve of the present invention is particularly suitable as an excess flow prevention valve for use in hydrogen supply piping equipment at hydrogen stations. Figure 1 shows an embodiment of the excess flow prevention valve of the present invention in the open state. Figure 2 shows an isolated perspective view of the excess flow prevention valve of Figure 1, and Figure 3 shows an enlarged cross-sectional view of the essential parts of the excess flow prevention valve of Figure 1 in the open state.

In the figure, the excess flow prevention valve is composed 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 assembled 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. In the excess flow prevention valve in Figure 1, the left side is the primary side and the right side is the secondary side.

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

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, with the outer periphery rising 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 forms the secondary side of the fluid flow passage 11 is formed on the inner periphery of 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 primary side inner periphery of this mounting portion 14. A reduced diameter abutment engagement surface 16 is formed on the secondary side (right side) of the mounting portion 14, and one end side (right end) of the resiliently biased spring member 4 is provided to abut and engage with this abutment engagement surface 16.

An opposing surface 20 is provided on the inside 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 with a larger diameter than the mounting portion 14 is formed to a predetermined depth on the inner diameter side of this opposing surface 20 near the fluid flow path 11. This annular step portion 21 is provided with a diameter slightly larger than the outer diameter of the holder member 3.

On the outer diameter side of the annular step 21 on the body member side opposing surface 20, an obtuse edge seal portion 22 is formed so as to protrude in a generally tapered manner in the inner diameter direction, and further on the outer diameter side of this edge seal portion 22, an enlarged annular recess 23 is formed next to this edge seal portion 22.

On the other hand, the cap member 2 has a male thread 30 formed on the outer periphery on the joining side with the body member 1 (the right side in the figure) that can be screwed into the female thread 12. 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.

An opposing surface 32 is provided on the joint end surface side of the cap member 2 with the body member 1, and on the inner diameter side of this opposing surface 32 near the fluid flow path 11, an annular step 33 with a step portion with a larger diameter than the fluid flow path 11 is formed deeper in the flow path direction than the annular step 21 of the body member 1 in this example. The annular step 33 is provided at a predetermined depth with a diameter approximately 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.

Furthermore, on the outer diameter side of the annular step portion 33 of the cap member side opposing surface 32, an obtuse edge seal portion 34 is formed that protrudes in an approximately tapered manner 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.

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

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.

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 (cap member 2 side) end of the body main body 10 is provided with a primary side joint 35 with an internal thread, and the secondary side (body member 1 side) end is provided with a secondary side joint 36 with an internal thread. 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.

The holder member 3 is formed to a size that can be installed in the storage space S, and an annular groove 40 is formed on the outer diameter side of the holder member 3 that faces the opposing 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 that faces the opposing surface 32 of the cap member 2, V-shaped notched grooves 41 are formed at two equal intervals from the center side to the outer periphery, and fluid can pass through the notched grooves 41.

A receiving section 42 consisting of a communicating hole is formed on the inner diameter side of the notched groove 41, and the spring member 4 is provided so that it can be attached to the receiving section 42. In the figure, a reduced diameter abutment locking surface 43 is formed on the right side of the receiving section 42, and one end side (right end) of the spring member 4 resiliently biased against this abutment locking surface 43 is provided so that it can abut and lock. A valve seat portion 44 is formed on the left open end side of the receiving section 42, against which the first valve body 5 can abut and seal.

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 abut against the opposing surface of the annular step portion 21. This 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 with which they press against each other. When the cap member 2 and the body member 1 are joined, this cushioning member 7 can contract in response to the joining force. It also has the function of fixing the holder member 3 to the main body 10.

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 must be at least equal to or greater than the amount of tightening between the cap member 2 and the body member 1 using the clearance G1, and may be at most equal to the clearance G1.

Furthermore, if the holder member 3 protrudes too far from the groove 40 toward the annular step 21, excessive tightening force between the body member 1 and the cap member 2 is required, whereas if the protrusion is too small, the holder member 3 cannot be fixed because it cannot abut against the annular step 21. Therefore, the protrusion amount of the buffer member 7 must be at least sufficient to allow the body member 1 and the cap member 2 to abut in a 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.

A gasket 8 formed with 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 while being 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 clamped between the body member 1 and the cap member 2 within the storage space S so that the gasket 8 passes through the inner diameter side of the gasket 8.

By disposing a notch groove 41 between the holder member 3 and the cap member 2, 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 are communicated in the inner and outer periphery direction through the notch 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 following this notch 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 of the holder member 3 to the location where the buffer member 7 is attached.

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

The first valve body 5 and the second valve body 6 are formed of a resin material such as polyetheretherketone (PEEK) or polyimide (PI), which belong to the super engineering plastics. A part of each of them is formed with an enlarged disk portion 50, 51, and a seal portion 52, 53 is formed at the secondary outer periphery of the disk portion 50, 51, and each seal portion 52, 53 is arranged to be able to abut and seal against the valve seat portion 44, 15 described above, respectively.

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

The long cylindrical 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 cylindrical portion 61 of the second valve body 6 is formed with an outer diameter that allows it to be inserted into the attachment portion 14 .
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 the flow of fluid to the secondary side is prevented when this second valve body is closed.

In some cases, the second valve body 6 may also be designed to allow a small amount of fluid to flow 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 tolerable 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.

The first valve body 5 is disposed between the cap member 2 and the accommodation section 42 of the holder member 3 in the primary side flow passage 31 of the cap member 2, and its secondary side is loosely fitted into the accommodation section 42. The spring member 4 is accommodated in a resilient state between the abutment and engagement surface 64 of the first valve body 5 and the abutment and engagement surface 43 of the holder member 3, and the first valve body 5 is normally resilient toward 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 toward the secondary side (rightward in the figure) against the resilient force of the spring member 4, and when the fluid pressure exceeds the resilient force of the spring member 4, the seal portion 52 abuts against the valve seat portion 44 to seal and close the valve.

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 into the mounting portion 14. The spring member 4 is accommodated in a resilient engagement state between the abutment and engagement surface 65 of the second valve body 6 and the abutment and engagement surface 16 of the body member 1, and as in the case of the first valve body 5, the second valve body 6 is normally resilient-biased by the spring member 4 to the primary side (leftward in the figure) 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, its seal portion 53 abuts and seals against the valve seat portion 15 to close the valve.

In this case, the resilient force applied to the first valve body 5 by the spring member 4 is FA, and the resilient force applied to the second valve body by the spring member 4 is FB. These are set so that the resilient force FA < resilient force FB. This allows for a two-stage operation in which the first valve body 5 first operates, and then the second valve body 6 operates, depending on the pressure difference between the primary and secondary sides of the main body 10 centered on the holder member 3.

In the above embodiment, the buffer member 7 is attached to the holder member 3 on the side facing the facing surface 20 of the body member 1, but this buffer member 7 only needs to be attached to the side facing the facing 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 facing surfaces 20, 32 of both the body member 1 and the cap member 2.

In addition, the buffer member 7 may be fixed by providing a groove in the body member 1 or the cap member 2, rather than by 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 multiple members.

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 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 for positioning.

The notch grooves 41 of the holder member 3 may be formed in one location or in three or more locations. Even if they are formed in three or more locations, they should be formed radially at equal intervals from the center to the outer periphery. The notch grooves 41 may be provided in a cross-sectional shape other than a V-shape, and for example, a notch groove with a rectangular cross-section may be formed.

When assembling the above-mentioned excess flow prevention valve, the body member 1 is positioned 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 center of the holder member 3 is placed on top of this second valve body 6 with its outer diameter side placed 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 tube 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.

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. This positions the holder member 3 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.

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 increase the clamping pressure, improving the sealing performance.

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.

As a result, when high-pressure hydrogen (high-pressure fluid) flows in at the 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 communication hole portions 62, 63 have an opening area sufficient to allow the normal flow rate to flow, preventing a pressure difference between the primary side and the secondary side.

If damage occurs to equipment, valves, or piping (not shown) on the secondary side of the excess flow prevention valve, causing the secondary flow rate to become 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.

When this pressure difference increases, due to the relationship that the resilient force FA applied to the first valve body 5 is smaller than the resilient force FB applied to the second valve body, as shown in FIG. 4, the first valve body 5, which has a smaller resistance to the direction of fluid flow, moves first to the right in the figure, and the seal portion 52 seats on the valve seat portion 44, resulting in a closed valve state. At this time, since the through hole 70 maintains a state of communication with the accommodation portion 42 of the holder member 3, fluid continues to flow from the primary side to the secondary side through this 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 and secondary sides.

Furthermore, when the secondary flow rate of the excess flow prevention valve increases, the pressure in the secondary flow path 13 also increases accordingly, but 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 second valve body 6 moves to the right as shown in Figure 5 due to the pressure difference, and its seal portion 53 seats on the valve seat portion 15, closing the valve and blocking the flow path.

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, followed by the second valve body 5. This allows each valve body 5, 6 to operate and reliably close the flow path when excessive outflow occurs on the secondary side 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 becoming completely closed and preventing the entire excessive flow prevention valve from malfunctioning. In addition, by not entering a completely closed state, the first valve body 5 quickly returns to the open state when the temporary sudden flow is resolved.

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 storage space S through a gasket 8 made of copper or copper alloy that is attached at its outer periphery between the body member 1 and the cap member 2, so that the gasket 8 is sandwiched 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 contracting, while maintaining a sufficient sealing performance due to the pressure contact force in the clamping direction, and external leakage can be reliably prevented.

In addition, 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 the buffer member 7, allowing the body main body 10 to be assembled while providing optimal sealing performance from the gasket 8, and the sealing performance can be restored by further tightening.

The buffer member 7 prevents an excessively large gap between the holder member 3 and the storage space S, and also prevents the holder member 3 from chattering due to fluid.

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 for mounting the holder member 3 can be reduced to a minimum, thereby simplifying the structure and making it compact.

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. Therefore, whether the first valve body 5 is in the open or closed state, the pressure is equalized from the primary flow path 31 to the buffer member 7 through the communication passage T, and the application of excessive fluid pressure to the buffer member 7 is avoided. Moreover, the communication passage T is always maintained by the V-shaped notch 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.

A gap may also 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 have to be completely sealed as long as the structure is such that the secondary flow path 13 can be blocked when the second valve body 6 is closed.

Although the embodiment of the present invention has been described in detail above, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the invention as described in the claims of the present invention.

REFERENCE SIGNS LIST 1 Body member 2 Cap member 3 Holder member 4 Spring member 5 First valve body 6 Second valve body 7 Cushioning member 8 Gasket 10 Main body 11 Fluid flow path 20, 32 Opposing surface 21, 33 Annular step portion S Storage space T Communication passage

Claims (3)

A tubular body member and a cap member are joined to form a body main body with an internal fluid flow path, and a storage space is formed near the opposing surface of the body main body, which communicates with the fluid flow path and stores a cylindrical holder member. 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 the secondary side of the holder member housed in the storage space in a state in which the valve can be closed by the pressure of the fluid. 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 this annular step portion to position it. The first valve body and the second valve body are attached in series to the primary side and the secondary side, respectively, of 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. The excess flow prevention valve according to claim 1, in which a long cylindrical portion is formed on the secondary side of the second valve body, and the long cylindrical portion is formed with an outer diameter that allows it to be inserted into the mounting portion. 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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