JP2001314964A - Safety device for gas welding and cutting work - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a safety device for gas welding and cutting work which blocks backfire flame and reverse-flow gas in passage, and shuts off the passage even when reverse-flow gas pressure accompanied by the occurrence of fire flame is relatively low, and which makes return operation easy. SOLUTION: A check valve 3 inside a shutoff portion cylindrical body 2 blocks reverse-flow, and a shutoff valve 4 shuts off a normal flow. An arrester pin 21 fixed with the shutoff valve 4 hangs over an arrester wall 2b to restrain it's shutoff condition, so as to enable the return operation by a shutoff/release ring 6 fixed with the arrester pin 21. And the device is provided with an antiflash filter 8 which blocks fire flame but passes fuel gas inside an antiflash portion cylindrical body 7, a shutoff valve bar 11 is integrated into the antiflash portion cylindrical body 7 and the antiflash filter 8, guided inside a receiving seat 9 for the antiflash filter 8 fitted with a fuse metal 13 presses the fuse mutual 13 to the secondary side by a spring 47. When the fuse-metal 13 is melted by fire flame, the shutoff valve bar 11 shuts off the flowing passage of the antiflash portion cylindrical body.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backflow to a flammable gas supply source when performing a gas welding, cutting, heating or similar work using a flammable gas and oxygen (or compressed air). And a safety device for preventing a reverse flame.

[0002]

2. Description of the Related Art Conventional safety devices for gas welding / cutting work are:
When performing gas welding, cutting, heating or similar work using flammable gas and oxygen (or compressed air), the passage of the flame must be prevented to prevent a back flame to the flammable gas supply side. It is known that the flow is blocked by a flame-extinguishing means provided with a flame-extinguishing element (sintered metal), and a shut-off valve is operated by a backflow pressure to interrupt a normal flow.

[0003]

However, the conventional safety device for gas welding / cutting operation is based on the difference between the mixing ratio of combustible gas and oxygen (or air) and the pressure of the mixed gas.
From the abnormally high explosive backflow pressure caused by the flame,
In the case where various states can occur, such as when only a very low backflow pressure is generated, in the case where the shutoff valve is operated by the backflow pressure to form a shutoff state and the shutoff state is held by the restraining means, Since the spring is used as the return means of the spring, it is necessary to operate the shut-off valve for forming the shut-off state against the force of the spring. Unless a stronger backflow pressure is generated, the cutoff state cannot be formed. In the case of exposing a part of the shut-off valve to the outside and returning from the shut-off state by the force of the spring, the internal pressure is applied to the shut-off valve even by the normal flow pressure. It is necessary to keep the shut-off valve in the open position by the force of the spring, and the backflow pressure required to form the shut-off state is greater than the spring force to return from the shut-off state or the maximum working pressure of flammable gas. Otherwise, a blocking state cannot be formed. As described above, there is a problem that a low backflow pressure cannot reliably form a shut-off state, and a normal flow flows to cause a secondary fire.

The present invention solves the above-mentioned problems of the prior art in a case where the backflow pressure accompanying the generation of a flame is relatively low, the backflow pressure is extremely low, and the combustible gas continues to burn in the flow passage. Also has means for reliably blocking the back flame and blocking the normal flow, means for restraining the blocked state, and means for returning from the blocked state. The purpose is to provide a vessel.

[0005]

According to the present invention, there is provided a safety device for gas welding / cutting work, comprising a second opening 1b at an end of a cylindrical body 1d having a flow path therein and a third opening at the other end. 1c is formed, and extends in a direction intersecting the cylindrical body portion 1d, and has a first opening 1a formed at an end on the extension thereof, and has a flow path communicating with the cylindrical body portion 1d. The configured three-way channel body 1, a tubular blocking section cylinder 2 connected to the first opening 1 a of the three-way channel body 1, and a flammable gas supply side at an end of the blocking section cylinder 2. Reciprocally open the flow path against the pressing force of the spring 45 by normal flow, being urged to the primary side by the spring 45 inside the blocking unit cylinder 2 and closing the flow path. Check valve 3 and a shut-off valve 4 which is located on the primary side of the check valve 3 and has a restraining pin 21 fixed thereto and is capable of rotating and reciprocating. , The cylindrical wall of the blocking part cylinder 2 is constrained pin groove 2a and restraining wall on the primary side of the restraint pin groove 2a 2
b, the check valve 3 and the shut-off valve 4 are moved to the primary side by receiving the backflow pressure, and the restraining pin 21 fixed to the shut-off valve 4 is guided by the restraining pin groove 2a so that the restraining wall 2b is formed. The closing pin 21 fixed to the shut-off valve 4 is closed even when a force for moving the normal flow and moving the shut-off valve 4 to the secondary side is applied after closing the flow path inside the shut-off portion cylinder 2 at the position A means for catching on the wall portion 2b and restraining the blocking state at that position, and a portion where the restraining pin 21 fixed to the shutoff valve 4 penetrates the restraining pin groove 2a and is exposed to the outside of the blocking portion cylinder 2 is a blocking portion. The outer peripheral portion of the cylindrical body 2 is fixed to a shut-off / release ring 6 fitted so as to be able to rotate and reciprocate, and the shut-off / release ring 6 can be manually operated to operate the shut-off valve 4 to open the flow path. And the flame-extinguishing unit cylinder 7 is connected to the second opening 1b, and the flammable gas The extinguishing means is provided with an extinguishing filter 8 for passing through but preventing the flame, and is guided inside the extinguishing filter seat 9 in which the fusible metal 13 is embedded, and incorporated into the extinguishing section cylinder 7 and the inside of the extinguishing filter 8. The shut-off valve rod 11 is moved by the spring 47
The flow path is opened in a state in which is pressed, and a blocking means for closing the flow path of the flame-extinguishing unit cylindrical body 7 when the fusible metal 13 is melted by the heat of the flame, and the stopper 5 is attached to the third opening 1c. And means for releasing the internal pressure.

[0006] The flame-extinguishing unit cylinder 7 is provided with the second
A flame-extinguishing tube cap 10 having a means for connecting to a hose connection joint is connected to an end of the flame-extinguishing tube 2 and connected to the opening 1b. Cylindrical extinguishing filter 8 that passes through but blocks back flame
An annular groove 7e is formed on the end face of the large-diameter portion 7a inside the flame-extinguishing unit cylinder 7.
And the flame-extinguishing filter seat 9 screw-fitted to the inner peripheral surface of the end of the flame-extinguishing unit cylindrical body 7 at the portion where the O-ring 37 is fitted into
Packings 36 are respectively joined to both end surfaces of the flame-extinguishing filter 8 between a portion where the O-ring 38 is fitted into the annular groove 9b on the end surface of the flame-extinguishing filter 8 and screw-fit inside the end portion of the flame-extinguishing unit cylinder 7. The flame-extinguishing filter seat 9 is press-fitted and assembled, and is positioned on the circumference of the end face of the flame-extinguishing filter seat 9 located at the center of the gap between the outer periphery of the flame-extinguishing filter 8 and the large-diameter portion 7a of the inner wall of the flame-extinguishing tube 7 It has a plurality of through-holes 9a, and the normal flow passes through the cylindrical wall from the inside of the flame-extinguishing filter 8, passes through the through-hole 9a of the flame-extinguishing filter seat 9,
The reverse flame passes through the through hole 9a from the secondary side of the flame extinguishing filter seat 9.
And the flame extinguishing means for extinguishing the flame when passing through the cylindrical wall from the outer peripheral surface of the flame extinguishing filter 8.

The shut-off valve rod 11 has an outer peripheral surface formed of a large-diameter portion 11a, a middle-diameter portion 11b, and a small-diameter portion 11c from one side, and is provided inside the large-diameter portion 11a and the middle-diameter portion 11b. A cylindrical hole 11e and a medium-diameter portion 11b whose next side is sealed.
Of the flame-extinguishing unit cylinder 7 is screwed into the primary end of the flame-extinguishing unit cylinder 7, and is always connected to the spring receiving seat 26 having a through-hole therein. While being urged to the next side, the fire-extinguishing filter seat 9 in which the fusible metal 13 is fitted airtightly by the O-ring 39 fitted in the secondary end of the small diameter portion 11c of the shutoff valve rod 11. An O-ring 40 which is fitted inside so as to be able to move forward, and which is fitted into the middle diameter portion 11b of the shutoff valve rod 11 in a state of abutting against the end surface of the fusible metal 13.
And a shutoff means for opening a flow path between the outside of the tube and the small-diameter portion 7c of the inner wall of the flame-extinguishing unit cylinder 7, and closing the flow path when the fusible metal 13 is melted by the heat of the flame. .

The restraining pin 21 is vertically fixed to the outer peripheral wall of the shut-off valve 4, and the restraining pin ring 22 is rotatably fitted into the restraining pin 21 to reciprocate in the restraining pin groove 2a of the blocking portion cylinder 2. The locking pin 21 is attached to the cylinder wall of the blocking / release ring 6 at the exposed portion of the locking pin groove 2a.

The term "primary side" referred to in the claims means the supply source of flammable gas with respect to the gas welding / cutting safety device of the present invention and the individual members constituting the device.
The "secondary side" means the blow pipe side with respect to the gas welding / cutting safety device of the present invention and the individual members constituting the device.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described based on embodiments with reference to the drawings. In FIG. 1, a gas welding and cutting operation safety device according to the present invention is a cylindrical body having a flow path in which a second opening 1b is formed at one end and a third opening 1c is formed at the other end. The first opening 1a is formed in the portion 1d in a direction intersecting the cylindrical body portion 1d and at an end on the extension thereof.

[0013] A tubular blocking section tube 2 is provided at the first opening 1 a of the three-way flow path body 1 via an O-ring 30, and a tubular flame-extinguishing section tubular body 7 is provided at the second opening via an O-ring 34. A stopper 5 is screwed into the three-way channel body 1 in an airtight manner through the O-ring 41 in the third opening 1c.

A cap nut 23 for connecting to a pressure regulator (not shown) on the flammable gas supply side is attached via a C-pin 24 to a primary end portion of the shut-off section cylinder 2. 7
A cylindrical cap 10 for a flame-extinguishing unit having a flow passage therein at the outer peripheral portion of the secondary side end thereof is screwed in an airtight manner via an O-ring 35, and the secondary of the fire-extinguishing unit cylindrical cap 10 is formed. An external thread for connection to a hose connection joint (not shown) is attached to the side end.

In a normal flow, the combustible gas flows from the primary side (arrow A) of the shut-off section cylinder 2 to the secondary side of the flame-extinguishing section cylinder 7.

The stopper 5 attached to the third opening 1c exposes the ventilation hole 5a, whose primary side is sealed and communicates with the filter cylinder hole 5b, to the outside by loosening its screw, thereby exposing the pressure in the flow passage. Is released.

A check valve 3 that can reciprocate inside the shut-off portion tube 2 and a restraint formed by a groove in the cylindrical wall of the shut-off portion 2 in a shape of a part in the longitudinal direction of the spiral shape. A pin groove 2a and a constraining wall 2b at the tip of the primary side of the constraining pin groove 2a are provided. It is fixed. When the restraining pin 21 moves in the restraining pin groove, a rotatable restraining pin ring 22 is fitted into the restraining pin 21 in order to reduce friction with the wall of the restraining pin groove.

The check valve 3 has a small-diameter portion 3 a and a large-diameter portion 3
b, the small-diameter portion 3a side is fitted into the blocking portion cylindrical body 2 facing the primary side, and the O-ring 31 is fitted into the outer peripheral surface of the small-diameter portion 3a, Small diameter part 3
The inside of the front end portion is sealed, and a plurality of ventilation holes 3c communicate with the inside near the rear (secondary side) of the O-ring 31. A circular hole 3d larger than the hole inside the small diameter portion 3a is formed inside the large diameter portion 3b, and a spring 45 is fitted therein.
Is joined to a spring seat 25 having a through hole in the center at the secondary end thereof, and is constantly urged to the primary side to press the check valve 3 toward the primary side. Is air-tightly joined to the secondary side end of the air passage to close the flow path.

The shut-off valve 4 has a small-diameter portion 4a and a large-diameter portion 4
The small-diameter portion 4a has a primary-side end sealed and is fitted inside the blocking portion cylinder 2 so as to be able to rotate and reciprocate. An O-ring 32 is fitted into the outer peripheral surface of the small diameter portion 4a, and a plurality of ventilation holes 4c communicating therewith are opened near the rear (secondary side). A plurality of cylindrical restraining pins 21 are fixed to the central portion of the large diameter portion 4b perpendicularly to the outer circumferential surface thereof. Even when the ring 33 is fitted and the shut-off valve 4 reciprocates with rotation, the airtightness is maintained with respect to the restricting pin groove 2a of the shut-off tube 2.

Restraining pin 21 fixed to shutoff valve 4
Is provided on the blocking / release ring 6 which is exposed to the outside through the restraining pin groove 2a of the blocking portion cylinder 2 and whose exposed portion is rotatably and reciprocally mounted on the outer peripheral portion of the blocking portion cylinder 2. It is fixed. The blocking / releasing ring may be constantly urged to the secondary side with a relatively weak force by a spring 46 fitted over the outer periphery of the blocking portion cylinder 2 with a shoulder.

The inner peripheral surface of the flame-extinguishing unit cylinder 7 connected to the second opening 1b of the three-way channel body 1 has a medium-diameter portion 7 from the primary side.
b, formed from the small diameter portion 7c and the large diameter portion 7a, and the large diameter portion 7a
On the inner peripheral surface of the secondary side end of the above, there is a threaded portion into which the flame extinguishing filter seat 9 is screwed. The primary end face of the large-diameter portion 7a has an annular groove 7e and an O-ring 37.
Is fitted.

The cylindrical flame-extinguishing filter seat 9 has an outer peripheral surface formed of a small-diameter portion 9c and a large-diameter portion 9d having a screw, and has an annular groove 9b in the primary end surface of the large-diameter portion 9d. 38, and a plurality of through-holes 9 extending in the center line direction on the circumference located between the annular groove 9b and the large diameter portion 9d.
a.

A tubular flame quenching filter 8 that allows flammable gas to pass through but blocks the flame has a fire-resistant packing 36 joined to both ends of the flame quenching filter 8 and fitted into an annular groove 7e of the flame quenching unit cylinder 7. Between the O-ring 37 and the O-ring 38 fitted into the annular groove 9b of the flame-extinguishing filter seat 9, the secondary end of the flame-extinguishing filter 8 is attached to the outer peripheral surface of the small-diameter portion 9c of the flame-extinguishing filter seat 9. The inner peripheral surface of the portion is guided, and is crimped and assembled by the screw of the flame extinction filter seat 9.

A fusible metal cap 14 having a cylindrical hole on the center line of the extinguishing filter seat 9 and having a cylindrical end sealed at a secondary end of the cylindrical hole. 1
3 is buried, the fusible metal cap 14 has an opening facing the primary side, is screwed in, has an outer peripheral surface near the bottom and a ventilation hole communicating with the outside at the bottom, and a flame is directly applied to the fusible metal 13. It is designed to touch.

The shut-off valve rod 11 has an outer peripheral surface formed of a large-diameter portion 11a, a medium-diameter portion 11b, and a small-diameter portion 11c from the primary side, and the secondary side is located inside the large-diameter portion 11a and the medium-diameter portion 11b. Having a sealed cylindrical hole 11e;
An O-ring 40 is fitted on the outer peripheral surface between the middle diameter portion 11b and the small diameter portion 11c of the shut-off valve rod 11, and has a ventilation hole 11d near the primary side of the O-ring 40 communicating with the cylindrical hole 11e. .

An O-ring 39 is fitted into the secondary end of the small-diameter portion 11c of the shutoff valve rod 11, and is fitted in a cylindrical hole of the flame-extinguishing filter seat 9 in a reciprocating and airtight manner. The large-diameter portion 11a of the rod 11 is reciprocally fitted to the inner peripheral surface 7c of the primary end of the flame-extinguishing unit cylinder 7.

[0025] A spring receiving seat 26 having a hole in the center and screwed into the primary end of the flame-extinguishing unit cylinder 7 is joined thereto.
The shut-off valve rod 11 is always pressed to the secondary side by the spring 47 inserted into the cylindrical hole 11e of the shut-off valve rod 11, and hits the fusible metal 13. In this state, the flow path between the outside of the O-ring 40 of the shutoff valve rod 11 and the small diameter portions 7b and 7c of the inner wall of the shutoff cylinder 7 is open.

Next, the operation of the above-described embodiment will be described. In FIG. 1, the normal flow of the flammable gas is
Is connected to a device (not shown) on the flammable gas supply side by a cap nut 23 attached to the cylinder, and flows into the inside of the blocking unit cylinder 2 (arrow A).

A restraining pin 21 fixed to the shut-off valve 4
However, in the state in which it is located at the secondary side end of the restraining pin groove 2 a, the normal flow is caused by the end face of the large diameter portion 2 c of the inner peripheral wall of the shut-off portion cylinder 2 and the O-ring 32 fitted into the shut-off valve 4. The flow path therebetween is opened, and flows from the outside of the small diameter portion 4a of the shut-off valve 4 to the inside of the shut-off valve 4 through the plurality of ventilation holes 4c.

The check valve 3, which is air-tightly urged to the secondary end of the shut-off valve 4 by the force of the spring 45, by the internal pressure of the normal flow flowing from the inside of the shut-off valve 4 to the secondary end. The passage is opened between the O-ring 31 fitted into the check valve 3 and the secondary end of the shut-off valve 4, and the vent hole is opened from outside the small diameter portion 3 a of the check valve 3. It flows to the first opening 1a of the three-way channel body 1 through 3c and enters the inside of the three-way channel body 1.

The third opening 1c of the three-way channel body 1 is sealed by a stopper 5 into which an O-ring 41 is fitted.
The combustible gas flowing into the three-way channel body 1 flows into the flame-extinguishing unit cylinder 7 from the second opening 1b, and the shut-off valve rod 11 is pushed to the secondary side by the spring 47 and is not dissolved. At a position where it comes into contact with the end face of the fusible metal 13, a cylindrical hole 11 e at the primary end of the shutoff valve rod 11 is inserted into the medium diameter portion 11.
b, passes through the gap between the outside of the O-ring 40 and the middle diameter portion 7b and the small diameter portion 7c of the inner peripheral surface of the flame-extinguishing unit cylinder 7 through the ventilation hole 11d of the cylinder wall, and is incorporated into the flame-extinguishing unit cylinder 7. It flows into the inside of the extinguishing filter 8 which is in operation.

From the inside of the flame-extinguishing filter 8, it passes through the cylindrical wall, passes through a flow path in the gap between the inner wall surface of the flame-extinguishing unit cylinder 7 and the outer peripheral surface of the flame-extinguishing filter 8, and passes through a plurality of flame-extinguishing filter seats 9. Passing through the space between the inside of the flame-extinguishing cylinder cap 10 and the secondary end of the flame-extinguishing filter seat 9 through the through-hole 9a,
It flows to a hose connection joint (not shown) connected to the flame-extinguishing unit cylindrical cap 10.

In FIG. 2, a hose connection joint (not shown)
When the backflow of oxygen (or compressed air) or the propagation of the flame is backflowed (reverse flame) from the side (arrow B), these are the caps 1 for the flame-extinguishing unit cylinder connected to the hose connection joint.
0 through the through-hole 10a at the secondary side end of the flame-extinguishing filter cylinder 9 and the space between the flame-extinguishing filter seat 9 and the plurality of through-holes 9a of the flame-extinguishing filter seat 9. The gas enters the gap between the inner wall of the body 7 and the outer wall of the flame extinguishing filter 8, passes through the cylindrical wall of the flame extinguishing filter 8, and enters the interior. The reverse flame is extinguished by the time it reaches the inside of the flame-extinguishing filter 8 and is gasified backflow.

A flame having a low backflow pressure that stays in the space between the flame-extinguishing unit cylindrical cap 10 and the flame-extinguishing filter seat 9 is
When the fusible metal 13 fitted into the end of the flame-extinguishing filter seat 9 is melted, the shut-off valve stem is pressed against the secondary side by the spring 47 against the end face of the fusible metal 13. 11 moves to the secondary side, and its shutoff valve rod 1
The O-ring 40 fitted in 1 is air-tightly joined to the end face of the inner diameter portion 7b of the inner wall of the flame-extinguishing unit cylinder 7 to block a normal flow of combustible gas. At this time, the backflow flame passes through the cylindrical wall of the flame extinguishing filter 8 from the outside before the fusible metal 13 is melted, the flame is extinguished and gas flows back.

The backflow gas passes through the gap between the O-ring 40 fitted into the small diameter portion of the shut-off valve rod 11 and the end face of the middle diameter portion 7b of the inner wall of the flame-extinguishing unit cylinder 7, and passes through the three-way flow passage 1
Flows back into the shut-off portion cylinder 2, and the O-ring 31 of the check valve 3 is air-tightly joined to the inner peripheral wall 4 d of the secondary end of the shut-off valve 4 due to the pressure of the back-flow gas. Closed.

Further, at the same time that the check valve 3 pushes the shut-off valve 4 to the primary side, the restraining pin 21 fixed to the shut-off valve 4 is guided by the restraining pin groove 2a of the shut-off portion cylinder 2 to the primary side. At the position where it reaches the primary end of the restraining pin groove 2a and is fitted into the small diameter portion 4a of the shut-off valve 4.
The ring 32 is air-tightly joined to the end face of the middle diameter portion 2c of the blocking cylinder 2 to form a blocking state.

Thereafter, when the backflow pressure is released or the normal flow is higher than the backflow pressure, the shut-off valve 4 receives a force in the secondary direction, and the restraining pin 21 fixed to the shut-off valve 4 also becomes secondary. When moving to the side, the restraining pin 21 is caught by the restraining wall 2b (FIG. 3) on the secondary wall of the restraining pin groove 2a, the shutoff valve 4 is stopped from moving to the secondary side, and the shutoff state is maintained. .

In order to release the above-mentioned blocking state, the blocking / releasing ring 6 which is fixed to the restraining pin 21 and can be partially rotated and reciprocated is manually operated from the restraining wall 2b (FIG. 3). 21 is removed, and further moved to the secondary side along the restraining pin groove 2a (FIG. 3).

Furthermore, it is possible to move the restraining pin 21 to the position of the restraining wall 2b (FIG. 3) by manually operating the blocking / releasing ring, to form a blocking state, and to maintain the blocking state.

As described above, in the present embodiment, the first opening 1a of the three-way flow path body has a function of preventing backflow and blocking normal flow and a means for releasing the same, and the second opening 1b is provided with reverse flame. Since the quenching means for blocking and the function having means for sensing the temperature of the flame and blocking the normal flow are configured as independent functions and incorporated in the three-way channel body 1, they are assembled in each functional unit. Inspection is possible, making the work easier than when actually assembling and then generating a flame and inspecting it.Especially in the inspection of quenching means, even if there is a problem with the inspection result, other functions Components, especially O-rings, are not affected by the flame.

The flame-extinguishing filter 8 is incorporated in the flame-extinguishing unit cylindrical body 7, guided by the flame-extinguishing filter seat 9, fixed by screw fitting, and further protected by a flame-extinguishing unit cylindrical cap 10. Therefore, the state of the screw engagement of the flame quenching filter receiving seat 9 cannot be easily loosened from the outside, and the packing 36, the O-ring 37, and the O
It is possible to prevent the press-contact state of each joint portion of the ring 38 from being loosened, and the back flame can be surely passed through the flame-extinguishing filter 8.

Further, the joint with the end face of the quenching filter 8 is doubled by an elastic O-ring 37 fitted in an annular groove via a packing 36 and an O-ring 38 on the other end face. However, even if the extinguishing filter 8 receives an explosive extremely high pressure back flame and the end face of the extinguishing filter 8 is distorted, the O-ring 37 and the O-ring 38 fill the distortion, so that the extinguishing flame can be reliably removed. Can be passed.

[0041]

According to the first aspect of the present invention, depending on the mixing ratio of the combustible gas and oxygen (or air) and the difference in the pressure of the mixed gas, not only the backflow pressure caused by the flame generation but also the explosive one is high. Even when only a very low backflow pressure is generated, the backflow pressure at which the restraining pin 21 fixed to the shutoff valve 3 can move through the restraint pin groove 2a of the shutoff cylinder 2 is applied to the check valve 3 and the shutoff valve 4. The shut-off valve 4 is restricted even if pressure is applied in the normal flow direction at the position of the restriction wall 2b of the restriction pin groove 2a, so that the normal flow is reliably blocked. The occurrence of secondary fire can be prevented.

The shut-off / release ring 6 is fixed to the restraining pin 21, and the shut-off valve 4 is fixed to the restraining pin 21. Since the shut-off valves 4 are operated in conjunction with each other, the release from the shut-off state or the normal flow state is prevented. Can be easily operated by manually operating the shut-off / release ring 6. When the backflow pressure higher than the normal flow pressure remains on the secondary side when releasing from the cutoff state, the cutoff state cannot be released, but it is attached to the third opening 1c of the three-way channel body 1. The backflow pressure can be released by loosening the screw of the stopper 5 for degassing, so that the shut-off state can be easily released and the operability is good.

According to the second aspect, at both end surfaces of the flame-extinguishing filter 8, one end of the O-ring 37 is fitted in the annular groove 7e inside the flame-extinguishing unit cylindrical body 7, and the other end has the annular shape of the extinguishing end surface. The gasket 36 is joined to the O-ring 38 fitted in the groove 9b, and is press-fitted and fitted by the external screw of the flame-extinguishing filter seat 9; Even if the end face of the quenching filter 8 is distorted due to the explosive reverse flame, the distortion is filled by the O-ring 37 and the O-ring 38 and a gap cannot be formed, and the possibility that the flame propagates in the normal flow direction is extremely low. Become.

Further, since the flame-extinguishing filter seat 9 is screwed into the flame-extinguishing section cylinder 7 and covered with the flame-extinguishing section cylindrical cap 10, the flame-extinguishing section cylindrical cap 10 is provided. When attaching a hose connection fitting to
The installation state of the flame extinguishing filter 8 is not easily loosened from the outside, and the safety is further improved.

According to the third aspect, the flame extinguishing filter seat 9 is provided.
Since the fusible metal 13 fitted into the end of the fusible metal 13 is melted by heat at a relatively low temperature, the shut-off valve urged toward the secondary side by the spring 47 against the end face of the fusible metal 13 before melting is pressed. The rod 11 is made of a metal 1
When the 3 melts, the O-ring 40 that moves to the secondary side and is fitted into the shut-off valve rod is airtightly joined to the end surface of the middle diameter portion 7b of the inner wall of the flame-extinguishing unit cylinder 7, so that the backflow pressure is reduced. Even when a flame that does not accompany the flame is generated, the normal flow of the combustible gas can be cut off, thereby improving safety.

According to the fourth aspect, the constraint pin ring 22 is rotatably fitted to the constraint pin 21, so that the constraint pin 21 moves in the primary direction and the secondary direction of the constraint pin guide groove 2a. As a result, the shut-off valve 4 to which the restraining pin 21 is fixed is able to form a shut-off state by lower back pressure.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a main part showing a normal flow state of a safety device for gas welding / cutting work according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a main part showing a cut-off state of a safety device for gas welding / cutting work according to an embodiment of the present invention.

FIG. 3 is a perspective view illustrating a configuration of a blocking unit according to an embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Three-way flow path body 2 Shut-off part cylinder 3 Check valve 4 Shut-off valve 5 Stopcock 6 Shut-off / release ring 7 Flame extinguishing part cylinder 8 Flame extinguishing filter 9 Flame extinguishing filter seat 10 Flame extinguishing part cylinder cap 11 Shut-off valve rod 13 Possible Molten metal 14 Soluble metal cap 21 Restraining pin 22 Ring for restraining pin 23 Cap nut 24 C pin 25 Spring seat 26 Spring seat 30 O-ring 31 O-ring 32 o
Ring 33 o-ring 34 o-ring 35 o
Ring 36 packing 37 o ring 38 o
Ring 39 o-ring 40 o-ring 41 o
Ring 45 Spring 46 Spring 47 Spring

Claims (4)

[Claims] 1. A second opening 1b is formed at an end of a cylindrical body 1d having a flow path therein, and a third opening 1c is formed at the other end, and extends in a direction intersecting the cylindrical body 1d. A first opening 1a is formed at an end on the extension, and a three-way flow path body 1 formed by a cylindrical branch body 1e having a flow path communicating with the cylindrical body 1d; 1 is provided with a tubular blocking portion cylinder 2 connected to the opening 1a, and a means connected to a flammable gas supply side at a primary end of the blocking portion cylinder 2; The reciprocating check valve 3 is urged to the primary side by the spring 45 to close the flow path and opens the flow path against the pressing force of the spring 45 by normal flow. The O-ring 33 is fitted in the vicinity of both sides of the pin 21 so that the pin can be rotated and reciprocated. A restricting pin groove 2a is formed in the valve 4 and the cylindrical wall of the shut-off portion cylindrical body 2, and a restricting wall portion 2b is provided at a tip of a primary side of the restricting pin groove 2a. When receiving the backflow pressure and moving to the primary side, the restraining pin 21 fixed to the shut-off valve 4 is guided by the restraining pin groove 2a, stops at the position of the restraining wall 2b, and the flow inside the shut-off portion cylinder 2 is stopped. Even if the path is closed, and then the shut-off valve 4 is moved to the secondary side by normal flow and a force for opening the flow path is applied, the restraining pin 21 fixed to the shut-off valve 4 is caught by the restraining wall 2b and its position is reduced. And a portion in which the restraining pin 21 fixed to the shut-off valve 4 penetrates the restraining pin groove 2a and is exposed to the outside of the blocking portion cylindrical body 2 and the outer peripheral portion of the blocking portion cylindrical body 2 The shut-off / release ring 6 is fixed to the shut-off / release ring 6 fitted so as to be able to rotate and reciprocate. Means capable of the cut-off state and the released state by operating the shut-off valve 4 by the manual operation, antiphlogistic part cylinder 7 to the second opening 1b
And a quenching means provided with a quenching filter 8 for passing a flammable gas inside but blocking a flame;
Is guided inside the flame-extinguishing filter seat 9 in which is embedded, and the shut-off valve rod 11 incorporated in the flame-extinguishing unit cylindrical body 7 and the flame-extinguishing filter 8 is pressing the fusible metal 13 by the spring 47. When the fusible metal 13 is melted by the heat of the flame, the flame extinguishing unit cylinder 7 is opened.
A safety device for gas welding / cutting work, comprising: means for blocking the flow path of the above, and means for releasing the internal pressure by attaching the stopper 5 to the third opening 1c. 2. The flame-extinguishing unit cylindrical body cap has an end connected to the second opening 1b of the three-way channel body 1 and a means connected to a hose connection joint at the other end. 10
Is connected to the flame-extinguishing unit cylinder 7, and a cylindrical flame-extinguishing filter 8 that allows flammable gas to pass therethrough but blocks flames is provided in the end face of the large-diameter portion 7a inside the flame-extinguishing unit cylinder 7. O for 7e
A portion where the ring 37 is fitted, and a portion where the O-ring 38 is fitted into the annular groove 9b on the end face of the flame-extinguishing filter seat 9 which is screw-fitted on the inner peripheral surface of the secondary side end of the flame-extinguishing tube 7; In between, packings 36 are respectively joined to both end surfaces of the flame-extinguishing filter 8, and are pressed and assembled by a flame-extinguishing filter seat 9 fitted inside the end of the flame-extinguishing unit cylinder 7. A plurality of through holes 9a are formed on the circumference of the end face of the flame-extinguishing filter seat 9 located at the center of the gap between the outer peripheral wall and the large-diameter portion 7a of the inner wall of the flame-extinguishing unit cylinder 7.
The normal flow passes through the cylinder wall from the inside of the flame quenching filter 8 and passes through the through hole 9a of the flame quenching filter seat 9, and the reverse flame passes through the through hole 9a from the secondary side of the flame quenching filter seat 9. 2. A safety device for gas welding and cutting work according to claim 1, wherein a flame-extinguishing means for extinguishing the flame when passing through and passing through the cylindrical wall from the outer peripheral surface of the flame-extinguishing filter 8 is provided. 3. The shut-off valve rod 11 has an outer peripheral surface formed of a large-diameter portion 11a, a medium-diameter portion 11b, and a small-diameter portion 11c from the primary side, and is located at the large-diameter portion 11a and the medium-diameter portion 11b. The cylindrical hole 11e of which the secondary side is sealed and the middle diameter portion 1
1b is provided with a through hole 11d in the cylindrical wall, and is always screwed into the primary end of the flame-extinguishing unit cylindrical body 7 and attached to the spring receiving seat 26 having a through hole therein by being attached to the spring 47. While being urged to the secondary side, the flame-extinguishing filter seat 9 in which the fusible metal 13 is fitted airtightly by the O-ring 39 fitted in the secondary end of the small diameter portion 11c of the shut-off valve rod 11. O is fitted into the inside of the valve so as to be able to move forward, and is fitted into the end face of the middle diameter portion 11b of the shutoff valve rod 11 in a state of abutting against the end face of the fusible metal 13.
A flow path is opened in a gap between the outside of the ring 40 and the small-diameter portion 7c of the inner wall of the flame-extinguishing unit cylinder 7, and a shutoff means for closing the flow path when the fusible metal 13 is melted by the heat of the flame. The safety device for gas welding / cutting work according to claim 2. 4. The restraining pin 21 is vertically fixed to an outer peripheral wall of the shut-off valve 4, and a restraining pin ring 22 is rotatably fitted into the restraining pin 21 so that the restraining pin groove 2a of the blocking portion cylinder 2 is formed. The restraining pin 21 is mounted so as to be able to reciprocate, and the blocking / release ring 6 is attached to the exposed portion of the restraining pin groove 2a.
The safety device for gas welding / cutting work according to claim 1, wherein the safety device is fixed to the cylindrical wall of (1).