JP2002221299A - Pressure detection safety device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pressure detection safety device for a gas appliance using a small gas cylinder, in which its structure is rationalized by reducing the number of part items and also assembling man-hours, its reuse after actuation, namely its reset is facilitated, and operability is improved. SOLUTION: This device is composed such that a stem 16 is integrated with the piston of a check valve and cutoff valve, and the inside and outside of an actuation chamber 13 of a check valve are shut off by making the stem 16 detect the abnormal pressure of the small gas cylinder to retreat.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure sensing safety device for a gas appliance using a small gas container. The present invention relates to a pressure sensing safety device including a retractable stem, which detects the pressure when the internal pressure of a small gas container rises abnormally, and allows the gas passage to be shut off by the retractable stem.

[0002]

2. Description of the Related Art A gas appliance using a small gas container may sometimes be used unexpectedly, resulting in an abnormally high temperature of the small gas container and, in severe cases, a risk of explosion. was there. Although various safety devices have been developed to prevent this, Patent No. 2954
The one disclosed in Japanese Patent Publication No. 528 is one typical example. In the case of the present invention, as shown in FIG. 7, the check valve a and the stem b of the safety device work in cooperation with each other, but are incorporated separately and independently. For this reason, there are problems that the stem b itself and the number of parts related thereto are large, and the number of assembly steps is also large.

In addition, when the abnormally increased pressure acts on the stem b and the stem b is retracted, a pressure difference is generated on both sides of the seal portion d which blocks the inside and outside of the working chamber, so that the stem extension portion Only by operating the member f that restrains e, the stem b does not return automatically. Therefore, it is necessary to return the pressure in the working chamber to the normal pressure for reuse, and the operability is not good. There's a problem.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has been made to reduce the number of parts and the number of assembling steps by streamlining the configuration of a pressure sensing safety device for a gas appliance using a small gas container. It is intended to be realized by. Another object of the present invention is to provide a pressure-operated safety device with good operability that facilitates reuse after the pressure-operated safety device is activated, that is, resetting.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a stem in which a check valve and a piston of a shutoff valve are integrated, and the stem detects an abnormal pressure of a small gas cylinder and retreats. A structure that shuts off the gas passage is adopted.

More specifically, the present invention comprises a stem which is pushed by a nozzle portion of a small gas container when the small gas container is mounted, and which is capable of retracting a through hole of the apparatus main body against a spring, so that the internal pressure of the small gas container is abnormal. A pressure sensing safety device that senses the pressure when it rises and allows the stem to recede and shut off the gas passage. In a normal state, a spring comes into contact with the stem by a spring to shut off the gas passage. An operation in which a gasket is provided in front of an operating chamber provided with a gasket in the gas passage, and a gasket is provided with an internal gasket capable of shutting off the gas passage by coming into contact with the stem which has retreated due to abnormally increased pressure in an abnormal condition. Each is provided at the rear side of the chamber, and the gas ejected from the nozzle part can flow out to the decompression chamber through the working chamber by the stem leaving the outer seat part by mounting the small gas container. I have.

A specific structure of the above invention is a pressure sensing safety device including a stem for sensing the pressure when the internal pressure of a small gas container rises abnormally, and the gas passage can be shut off by the movement of the stem. The stem includes a member that penetrates a pressure sensing safety device main body having a pressure receiving portion that receives an internal pressure of the small gas container, and is slidable in a through hole of the pressure sensing safety device main body. An outer seat portion and an inner seat portion are provided in an operating chamber provided in the outer chamber, and the outer seat portion is in contact with the stem so as to be able to shut off the inside and outside of the operating chamber. The ejected gas is allowed to flow out of the working chamber, and the inner seat portion is configured to be able to shut off the inside and outside of the working chamber by contacting the stem with the stem retreating at the time of abnormality. It has become one restraining member for restraining the retracted stem is provided.

In the above invention, the pressure receiving portion for receiving the internal pressure of the small gas container can be formed at the front end of the stem, or at both the front end and the rear end of the gas passage.

[0009] The stem can be formed substantially of a single member or an assembly of two or more members.

[0010] The stem is biased forward from the pressure sensing safety device main body, and the bias is performed by a spring provided in the gas passage, a spring provided behind the gas passage, or both. Is good.

Further, the stem is hermetically sealed in the through hole of the safety device main body behind the gas passage by a seal member provided therein or by a seal member attached to the stem, so that the combustion gas entering the gas passage is sealed. The stem can be retracted under abnormal pressure.

Further, a seal member is provided on the stem in contact with one or both of the outer seat and the inner seat of the working chamber formed in the gas passage, or one of the outer seat and the inner seat is provided. Alternatively, it is preferable to provide a seal member in contact with the stem on both of them to complete the seal.

In the present invention, a check valve urged forward by a spring from the stem may be further provided in front of the stem.

Further, the restraining member constituting the present invention can be engaged with the rear end of the stem when the stem retreats to a position where it comes into contact with the inner seat, and can be released from restraint. It is preferable to use a torsion spring acting in the cross direction.

In implementing the present invention, the mounting structure of the small gas cylinder is constituted by a cover member provided at the front end of the stem, and a connection port member holding the cover member. It is preferable to provide a hole through which the front end of the stem can go in and out, and to have a nozzle receiving portion for abutting and pushing the nozzle portion when the small gas container is mounted.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A pressure sensing and safety device for a gas appliance according to the present invention has a stem which is pushed by a nozzle portion when a small gas container is mounted and which can retreat through a through hole of a device main body. When the internal pressure of the gas container rises abnormally, the present invention is applied to a pressure sensing safety device that senses the pressure and retreats the stem to shut off the gas passage.

The stem referred to in the present invention is configured as an integrated piston of a check valve and a shut-off valve in the prior art. The stem is provided through a through hole provided in the main body of the pressure sensing safety device. When the small gas container is mounted, the small gas container is urged forward by a means such as a spring, for example, toward the connection port for mounting the small gas container. This urging is necessary when the small gas container is mounted, but is not always necessary when the small gas container is not used or the small gas container is removed until the small gas container is mounted. When the stem senses an abnormally increased pressure, the stem retreats backward, that is, to the opposite side of the connection port. Therefore, the stem is provided with a pressure receiving portion that receives the ejection pressure when the internal pressure of the small gas cylinder rises abnormally. The pressure receiving section will be described later.

The gas passage referred to in the present invention means a portion for sealing a nozzle portion of a small gas cylinder when the cylinder is mounted, for example, a portion to which a gas primary pressure including an O-ring and a gas outlet to a decompression chamber is applied. Includes working room and is wider. The working chamber means a space in which a check valve and a shut-off valve are housed. The gas is received in the small gas container by being installed therein, and the gas is discharged from an outlet to a pressure regulator (generally referred to as a governor). Part in which the stem reciprocates. Also in this working chamber, the connection port for mounting the small gas container is referred to as the outside or the front side, and the direction in which the ejected gas flows is referred to as the inside or the rear side.

On the front side of the working chamber, there is provided an outer seat part which comes into contact with the stem by urging by a spring or the like so that the inside and outside of the working chamber can be shut off. This allows the stem to perform the function of a check valve. On the rear side of the working chamber, there is provided an inner seat portion which is pressed by the pressure when the pressure rises abnormally, comes into contact with the retracted stem, and can shut off the inside and outside of the working chamber. As a result, the stem acts as a shut-off valve, and is ready to function as a safety device. .

As can be seen from the above, in the present invention, the action of both the check valve and the shutoff valve is achieved by the movement of substantially one stem. That is, the stem acts as a check valve by contact with the outer seat, and acts as a shut-off valve by contact with the inner seat, and these are switched by movement of the stem. Then, when the stem is separated from the outer seat with the small gas container attached and the internal pressure has not yet risen abnormally, the gas passes through the working chamber and flows out to the pressure regulator (governor). .

It is desirable that such a stem has a substantially single structure. The substantially single structure means a structure in which a check valve and a shutoff valve (which also serves as a stem for pressure sensing) are combined and can be handled as one member. Therefore, it does not matter whether the stem is completely one-piece. Being a single member is preferable in that the number of partial points is small, but is not necessarily limited thereto.
It is also possible to connect and assemble a plurality of members with screws, for example.

The stem is configured to move back and forth through the through hole of the apparatus main body under the internal pressure of the small gas cylinder. Therefore, the stem is provided with a pressure receiving portion that receives the internal pressure of the small gas container. The pressure receiving portion is a portion that receives the gas pressure ejected from the small gas cylinder in relation to a portion of the rear end of the stem that is open to the atmosphere, as can be understood from embodiments described later. As this pressure receiving part,
First, the tip of the stem can be mentioned. Also,
The enlarged diameter portion of the stem provided in the gas passage can also correspond to this.

The stem is hermetically sealed at the rear side in the through hole and is slidably inserted in the through hole. As described above, atmospheric pressure is applied to the rear end of the stem, while the pressure receiving portion receives the gas pressure flowing out of the small gas cylinder. Therefore, when the pressure of the gas ejected from the small gas container is abnormally high with respect to the atmospheric pressure, the stem moves backward against the spring supporting the stem.
As a result, as described above, a part of the stem comes into contact with the inner seat portion of the working chamber to shut off the inside and outside of the working chamber.

In order to ensure the gas blocking action by such movement of the stem, it is preferable to attach an O-ring to the stem as a seal member. Further, a seal member such as a packing may be provided on at least one side of the outer seat portion and the inner seat portion. As will be described later in the embodiments, these sealing means may employ an appropriate form as needed.

The stem which has receded in the through hole due to the abnormal internal pressure must be restrained (locked) in that state. Therefore, at the rear end of the stem, there is provided a suitable means, for example, a restraining means constituted by a groove cut into the stem and a suitable engaging member fitted therein. It is preferable that the restraining means be a torsion spring acting in a cross direction with respect to the stem, since it can be reset by operating the knob of the tabletop gas stove.

In the present invention, a check valve urged forward by a spring from the stem may be further provided in front of the stem. Thus, the shut-off valve operates, and when the small gas cylinder is removed accordingly, the backflow of gas from the working chamber can be prevented.

Although the present invention can achieve the initial purpose by the above-mentioned structure, the number of parts and the assembly of the pressure sensing device of the present invention can be further improved by the following structure of the mounting portion of the small gas cylinder. Man-hours can be reduced. That is, the mounting portion structure of the small gas cylinder is constituted by a cover member provided at the front end of the stem and a connection port member holding the cover member, and the front end of the stem can enter and exit from the center of the cover member. A hole is provided, and a nozzle receiving portion is provided for pressing the nozzle portion into contact when the small gas container is mounted. An example of the specific structure is shown in the first embodiment. Note that the mounting structure of the small gas cylinder is not limited to the pressure sensing device of the present invention, but is not limited to the one that widely penetrates the pressure sensing device body of the small gas cylinder, but includes only the so-called check valve stem. Further, a check valve seat portion is provided on the inner surface of the cover member, and a base portion of a small gas cylinder, if necessary,
An O-ring is arranged for sealing with the nozzle portion.

Further, the mounting structure of the small gas cylinder has a hole in the center where the front end of the stem can go in and out, and a nozzle receiver which pushes the nozzle into the periphery of the hole when the small gas container is mounted. It is also possible to have a part. With this type, the cover member and the connection port member are integrated as compared with the above case, so that the number of parts is reduced and the number of assembling steps can be reduced.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, typical embodiments of the present invention will be described in detail with reference to the drawings. (Embodiment 1) FIGS. 1 and 2 are cross-sectional views of a pressure reducer 10 equipped with a pressure sensing safety device according to Embodiment 1 of the present invention, a so-called governor. The apparatus main body 11 of the present invention is attached to the pressure reducer 10 and is integrally formed therewith. A through hole 12 is formed in the main body 11, and a working chamber 13 having a gas flow port 25 communicating with a decompression chamber is provided in the first half thereof.
Is provided. The stem 16 extends through the through hole from its front end to its rear end. In this example, the working chamber 1
3 is provided with a spring accommodating portion 14 at the innermost portion thereof, and a pressing spring 19 installed therein urges the stem 16 forward.

The stem 16 is a shaft-like member slidably disposed in the through hole 12 in the axial direction, and extends from one end of the through hole 12 to the other end. This stem 16
Is a front end 17 pushed by the nozzle portion N of the small gas container.
have. In addition, a large diameter portion is also provided near the front end, and an O-ring is provided around the outer periphery of the large diameter portion with a sealing member 18.
It is attached as.

The stem 16 is pushed forward by a pressing spring 19 provided in the spring housing 14. That is, the stem 16 is provided with a pressing spring 19 between the large-diameter portion of the stem to which the sealing member 18 is attached and the innermost body of the gas passage, and the stem 16 is urged forward by the pressing spring 19. Pressed. The pressing spring 19
It is weaker than the spring built in the nozzle portion N of the small gas container, and has a strength capable of returning the stem 16 to the original position in a state where the small gas container is removed and the restraint of the stem 16 is released after the internal pressure abnormally rises. Have.

The rear half of the stem has an outer diameter slightly smaller than the inner diameter of the through hole, and is slidably disposed in the through hole 12. A seal member 24 is disposed in a part of the through hole through which the stem 16 slides, so that airtightness is maintained. Thus, the stem 13 can be retracted by the gas pressure applied to the front end of the stem 16.

The working chamber 13 is located in the first half of the through hole 12 provided in the main body 11 as described above. The working chamber 13 has, at the front, an extended portion having an inclined surface tapering inward, and an inner seat portion 15 is set on the tapered inclined surface of the extended portion. When the stem 13 retreats, the large diameter portion of the inner seat portion 15 comes into contact with the inner seat portion 15 via the seal member 18 so as to function as a shutoff valve. On the other hand, the outer seat portion 20 is provided in front of the working chamber 13. Specifically, it is provided on the inner surface of the cover member 22 provided on the front end 17 of the stem 16. A stem 13 is urged against the outer seat portion 20 by a pressing spring, and when the stem is at the original position, a large diameter portion thereof comes into contact with the sealing member 18 to act as a check valve. I have.

The cover member 22 has a hole 21 at the center thereof so as to be able to enter and exit, so that the nozzle portion N comes into contact with the small gas container and is pushed in when the small gas container is mounted. The cover member 22 used in this example is a metal part formed by press forming, which is held inside the connection port member 23. The cover member 22 can be replaced by a resin molded product.

The outer seat 20 defines the original position of the stem 16. The original position of the stem is a position when the stem 16 is urged forward by the spring 19, and is a reference of the stem position before the small gas cylinder is mounted on the pressure safety device. Stem front end 17 in position
Project out of the hole 21 (upper half of FIG. 1).

The stem 16 has an engaging portion 26 at its rearmost end. The engaging portion 26 is configured to restrict the axial movement of the stem 16 by engaging the restricting member 27 with the engaging portion 26. The restraining member 27 may be, for example, biased by a spring in the engagement direction, and the stem 16 may be released from the restraint and reset by releasing the engagement against the spring. As a method of operating the restraining member 27, an arbitrary method such as a method of directly operating a gas appliance, a method of operating a knob that controls ignition and extinguishing of a gas appliance, and the like can be used.

The operation of the first embodiment is as follows. In the state before use (before mounting a small gas cylinder) shown in the upper half of FIG. 1, the pressures on the outside and inside of the seal member 18 are substantially balanced, and the nozzle portion N of the small gas container is connected to the connection port. When inserted, the front end 17 of the stem 16 is pushed in at the tip of the nozzle, so that the sealing member 18 is separated inward from the outer seat portion 20, while the nozzle portion N is pushed in by the covering member 22 to open the valve even in a small gas appliance. . As a result, the ejected gas flows out into the cover member as shown in FIG. 2, and the outer seat portion 20 and the inner seat portion 1 in the working chamber 13 are discharged.
After passing through the gap between the stem 5 and the stem 16, it flows into the decompression chamber from the outflow passage 25. With this, if the instrument stopper is open,
The gas whose pressure has been adjusted by the diaphragm is in a state where it can flow to a burner or the like.

When the internal pressure of the small gas container rises abnormally, the stem 16 receives the force at the pressure receiving portion. When the force overcomes the pressing spring 19, the stem 16 retreats,
The sealing member 18 contacts the inner seat portion 15 and the working chamber 1
3 is cut off from the governor side. At the same time, the restraining member 27 engages with the stem engaging portion 26, so that the above-mentioned shut-off state is maintained, gas is not sent to the burner or the like, and combustion stops. In this operation, the large-diameter portion receives the internal pressure of the small gas container to more reliably shut off.

In this state, the sealing member 18 of the stem 16 is
Leaves the outer seat 20. Therefore, when the small gas container is unusually noticed and the small gas container is removed, the pressure upstream of the seal member 18 becomes the atmospheric pressure, and the pressure downstream thereof becomes the atmospheric pressure due to the discharge of the residual gas. Therefore, when the restraining member 27 is released, the stem 16 returns to the original position by the pressing spring 19, and the use can be continued by mounting a normal small gas container.

(Embodiment 2) FIG. 3 is a sectional view showing a decompressor 10 equipped with a pressure sensing safety device according to Embodiment 2 of the present invention in the same manner as in Embodiment 1. In the second embodiment,
A circumferential receiving groove 31 is provided at an intermediate portion of the stem 16 and the inner seal member 24 is attached, and the stem is urged forward by a pressing spring 32 from the rear of its outer wall. In this structure, the outer wall of the receiving groove 31 on the working chamber side also serves as a pressure receiving portion, and has a structure in which the abnormal pressure of the small gas cylinder can be easily detected as compared with the case of the first embodiment.

In the second embodiment, the cover member 22 and the connection port member 23 shown in the first embodiment are integrated into a single port member 30. Therefore, the outer seat portion 20 is formed on the base material. Thus, while having the same basic functions as those of the first embodiment, there is an advantage that the number of parts is reduced and the number of assembling steps can be reduced. In particular, the mouth member 30 and the stem 16 have a shape and structure that can be manufactured by die-casting, and the apparatus main body 11 is originally formed by die-casting. Therefore, since all three main parts can be manufactured by molding using metal or resin as a material, the assembly of the pressure sensing safety device and the governor can be performed extremely easily. Needless to say, the integration of the cover member and the connection port member can be applied to various embodiments including the case of the first embodiment.

Further, in the case of the second embodiment, the stem 16
Is directly controlled by the torsion spring 33 acting in the direction opposite to the direction of movement. Although this is also different from that of the first embodiment, it is needless to say that this can be applied to various embodiments including the case of the first embodiment. As described above, the configuration according to the second embodiment is different from the first embodiment in some parts. However, other configurations are basically the same as those in the first embodiment, and the same effects are obtained. Therefore, the same reference numerals as in the first embodiment are used in FIG. 3 and the detailed description is omitted.

(Embodiment 3) FIG. 4 shows a decompressor 10 equipped with a pressure sensing safety device according to Embodiment 3 of the present invention.
It is sectional drawing shown similarly to. In the third embodiment, a press spring 19 is provided in the working chamber 13 as in the first embodiment, but a spring accommodating portion 141 is provided behind a seal member 24 provided in a through hole through which the stem 16 slides. The stem 16 is urged forward by a pressing spring 191 installed there. That is, in the first embodiment shown in FIG. 1, the function of the push spring 19 is divided into the check spring 19 for the check valve and the push spring 191 for the shut-off valve. This makes it possible to operate the check valve more smoothly. The other points are the same as those in the first embodiment.
Is the same as

(Embodiment 4) FIG. 5 is a sectional view showing a decompressor 10 equipped with a pressure sensing safety device according to Embodiment 4 of the present invention in the same manner as in Embodiment 1. In the fourth embodiment,
Although the configuration is basically the same as that of the first embodiment, packings 34 and 35 are attached as seal members to the outer seat 20 and the inner seat 15 in the working chamber 13, respectively. By doing so, gas shut-off when the stem 16 comes into contact with the inner seat portion 20 and the outer seat portion 15 can be reliably performed. Further, the sealing member 18 provided on the stem side can be omitted, and the man-hour for assembling the stem can be reduced.
In addition, the packing 3 to the outer seat part 20 and the inner seat part 15 is used.
Attachment of 4, 35 may be made to any of them, or they may be replaced by one common packing.

(Embodiment 5) In Embodiment 5, as shown in FIG. 6, a check valve 36 urged forward by a spring from the stem 16 is further provided in front of the stem 16.
Thereby, the shut-off valve according to the device of the present invention operates, and when the small gas cylinder is removed, the combustion gas in the working chamber reversely flows and an accident such as ignition can be completely prevented. In this case, since a pressure difference is generated inside and outside the outer seat portion 20, the stem 16 cannot be returned to the original position simply by releasing the restraining member 27. However, after the fire is extinguished, the cylinder having the normal pressure is set. After that, the constraint member must be further released, but the use can be continued with the basic function of the present invention.

Although the embodiments of the present invention have been described with reference to the embodiments, the present invention can be carried out in various modes other than the above embodiments. For example, the stem may be separately provided with a seal member that contacts the outer seat and the inner seat. Further, the working chamber may be divided into a front portion and a rear portion connected by a gas passage, and the front may function as a check valve, and the rear may function as a shutoff valve. These modifications are free as long as they do not violate the technical idea.

[0047]

Since the present invention is constructed and operates as described above, the number of parts and the number of assembling steps required for assembling the pressure sensing safety device can be reduced, and the cost can be reduced. In addition, when the pressure sensing safety device is activated, the check valve is open, so there is no pressure difference between the front and rear of the inner seat. If the small gas cylinder is removed after the pressure sensing safety device is operated, there is an advantage that the reset operation can be performed immediately without the need to push back the stem again.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a pressure sensing safety device according to a first embodiment of the present invention. The upper half of the drawing shows a state in which a stem is in an original position, and the lower half thereof is operated with the safety device of the present invention. Indicates the status.

FIG. 2 is a cross-sectional view of the pressure sensing safety device according to the first embodiment that is normally used.

FIG. 3 is a cross-sectional view showing a pressure reducer 10 equipped with a pressure sensing safety device according to a second embodiment of the present invention, similarly to the first embodiment.

FIG. 4 is a cross-sectional view of a pressure sensing safety device according to a third embodiment.

FIG. 5 is a sectional view of a pressure sensing safety device according to a fourth embodiment.

FIG. 6 is a cross-sectional view of a pressure sensing safety device according to a fifth embodiment.

FIG. 7 is a sectional view of a pressure sensing safety device according to a conventional example.

[Explanation of symbols]

 10: decompressor 11: apparatus main body 12: through hole 13: working chamber 14: spring housing 141: spring housing 15: inner seat 16: stem 17: front end 18: sealing member 19: (stem 16 forward) Press) Spring 191: Push spring 20: Outer seat 21: Hole 22: Cover member 23: Connection port member 24: Seal member 25: Gas outlet to decompression chamber 26: Engagement portion 27: Engagement member 30: Mouth member in which cover member and connection port are integrated 31: Receiving groove 32: Press spring 33: Torsion spring 34: Inner seat packing 35: Outer seat packing 36: Check valve N: (Small gas container A) Nozzle

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kenji Suzuki 2-6-8, Moiwadai, Taishiro-ku, Sendai City, Miyagi Prefecture Sun Frontier Technology Co., Ltd. (72) Inventor Ryoichi Suganuma Iwatsuki-shi, Saitama 7915 In Asahi Works, Ltd. (72) Inventor Tomohiko Yokoyama 7915, Ojikake, Iwatsuki-shi, Saitama F-term in Asahi Works (Reference) 3E072 AA01 GA30 3K068 AA01 CB01 DA14

Claims (12)

[Claims] A small gas container is provided with a stem which is pushed by a nozzle portion when the small gas container is mounted, and which can retreat against a spring in a through-hole of the apparatus main body. When the internal pressure of the small gas container rises abnormally, the pressure is increased. A pressure sensing safety device that allows the stem to retract and shut off the gas passage by sensing the gas passage, and an outer seat portion that normally makes contact with the stem by a spring to shut off the gas passage when the gas passage is closed. In the front of the working chamber provided in the above, an inner seat portion which is capable of contacting the stem retreated by an abnormally raised pressure in the event of an abnormality and shut off the gas passage is provided on the rear side of the working chamber provided in the gas passage. A pressure sensing safety device wherein gas ejected from a nozzle portion is allowed to flow through the working chamber and flow out to a decompression chamber when the stem leaves the outer seat portion by mounting a small gas container. 2. A pressure sensing safety device comprising a stem for sensing an internal pressure of a small gas container when the internal pressure rises abnormally, wherein the gas passage can be shut off by moving the stem. A pressure sensing safety device body having a pressure receiving portion that receives the internal pressure of the pressure sensing safety device body, and is slidable in a through hole of the pressure sensing safety device body. An outer seat portion and an inner seat portion are provided, and the outer seat portion is in contact with the stem so that the inside and outside of the working chamber can be shut off. The inner seat portion retreats the stem in the event of an abnormality and makes it possible to shut off the inside and outside of the working chamber by contacting the stem, and the stem retains the retracted stem. A pressure sensing safety device comprising a binding member for bundling. 3. The pressure receiving portion for receiving the internal pressure of the small gas container,
3. The pressure sensing safety device according to claim 2, wherein the pressure sensing safety device is formed at a front end of the stem or at both the front end and the rear end of the gas passage. 4. The pressure sensing safety device according to claim 2, wherein the stem is substantially a single member or an assembly of two or more members. 5. The pressure sensing safety device according to claim 2, wherein the stem is biased forward from the pressure sensing safety device main body. 6. The pressure sensing safety device according to claim 5, wherein the biasing of the stem is performed by a spring provided in the gas passage, a spring provided behind the gas passage, or both of them. . 7. The stem according to claim 2, wherein the stem is hermetically sealed by a seal member provided in a through hole of the safety device main body behind the gas passage, or by a seal member attached to the stem. The pressure sensing safety device according to any one of the above. 8. The pressure sensing safety device according to claim 2, wherein the stem is provided with a seal member in contact with one or both of the outer seat portion and the inner seat portion. . 9. The pressure sensing safety device according to claim 2, wherein one or both of the outer seat portion and the inner seat portion is provided with a seal member that contacts the stem. . 10. The pressure sensing safety device according to claim 2, further comprising a check valve provided forwardly of the stem by a spring from the stem by a spring. 11. The restraining member engages with the rear end of the stem when the stem is retracted to a position where it contacts the inner seat,
The pressure sensing safety device according to any one of claims 2 to 10, wherein the device is capable of releasing restraint. 12. A cover member provided at a front end of a stem, and a connection port member holding the cover member, wherein the cover member has a hole at a central portion thereof through which a front end portion of the stem can enter and exit. Attachment structure of a small gas cylinder having a nozzle receiving part that pushes the nozzle part into contact when the small gas container is mounted.