JP2020101220A - Seal structure of connection part - Google Patents

Abstract

To provide a seal structure of a connection part capable of reliably inspecting air-tightness of an air-tightening seal member according to an initial air-tightness inspection, with respect to a seal structure of the connection part for connecting connection parts of two members to each other via the air-tightening seal member and fire-proof seal member.SOLUTION: An annular groove part 10 which is opened for the other side opposite face is provided along the whole region in a circumference direction on one side opposite face, of opposite faces opposite to each other in a connection state, an annular air-tightening seal member 21 and a fire-proof seal member 22 are stored in the annular groove part 10, the air-tightening seal member 21 is pressed and deformed by the other side opposite face in the connection state of the connection part, and the fire-proof seal member 22 is stored on a retired position of the annular groove part 10.SELECTED DRAWING: Figure 2

Description

The present invention relates to a seal structure for a connection part, and more particularly to a seal structure for a connection part provided with a fireproof seal member together with an airtight seal member.

For example, in order to connect two pipes through which a fluid flows in an airtight state, as in the case of connecting a joint member of a pipe to a connecting cylinder part of a gas tap, one pipe body is prevented from slipping off the other pipe body. There is a plug-in type that inserts into the state and a press-type that makes the flange parts that project to the connecting end of each tube face to face each other and presses and fixes them with screws etc., between the facing surfaces that contact each other at the time of connection In addition, there is known a seal structure in which an O-ring as an airtight seal member is interposed to ensure airtightness of a connection portion.

Specifically, in the plug-in type, either the inner peripheral surface of the outer cylinder located outside or the outer peripheral surface of the inner cylinder located inside, in the press type, the flanges opposed to each other. An annular groove portion, which opens toward the other surface, is circumferentially formed on either one of the facing end surfaces of the section, and an O-ring is housed in the annular groove portion. In this state, when the connecting portions of both pipes are connected as described above, the O-ring in the annular groove portion is pressed against the other surface and comes into close contact in a deformed state, so that the airtightness between the connecting portions is reduced. It is held, and leakage from the connecting portion of the two pipes can be prevented.

Moreover, what is shown in patent documents 1-2 is an O ring as an airtight seal member (hereinafter referred to as an airtight O ring), and an O ring as a resin fireproof seal member having a large coefficient of thermal expansion (hereinafter referred to as a fireproof member). O-ring) is also provided, and even if the air-tight O-ring disappears in the event of a fire, the fire-resistant O-ring thermally expands to ensure the air-tightness of the connection part and prevent gas leaks. Can be prevented.
In Patent Document 1, the airtight O-ring and the fireproof O-ring are separately housed in different grooves, and in Patent Document 2, they are housed together in the same groove.

JP, 2003-343778, A JP, 2005-155706, A

However, in the structure described above, the refractory O-ring is an annular body having substantially the same size as the airtight O-ring and is housed in the annular groove like the airtight seal member. In the connected state, the fireproof O-ring is also pressed to the opposing surface to a certain extent and is in close contact with the air-tightness O-ring, even under normal conditions. Therefore, in the initial airtightness inspection of the gas stopper, the airtight O-ring is flawed, foreign matter such as dust is attached, and further, the airtight O-ring has a sealing property such as forgetting to set it. Even if there is a deficiency that damages the pipe, the airtightness of the connecting portion of the pipe body is ensured by the sealability of the fireproof O-ring. Therefore, there is a problem that it is judged that the airtight O-ring to be inspected has the sealing property without confirming the sealing property.

The present invention has been made in view of the above problems, and in a seal structure of a connecting portion for connecting the connecting portions of two members to each other in an airtight state via an airtight sealing member and a fireproof sealing member, It is an object of the present invention to ensure that the airtightness of the airtight seal member can be inspected by the airtightness test.

Technical means for solving the above problems are
In the seal structure of the connecting portion, which keeps the opposing surfaces facing each other in the connected state in the airtight state on the outer periphery,
On one opposing surface, an annular groove portion that opens toward the other opposing surface is formed in the entire circumferential direction,
In the annular groove portion, an annular airtight seal member and an annular fireproof seal member made of a heat-expandable material are housed,
The airtight seal member is pressed and deformed by the other facing surface in a state of being accommodated in the annular groove portion when the connecting portions are connected to each other,
The fireproof seal member is housed at a position deeper than the open end of the annular groove.

The above technical means operate as follows.
The connecting portions are connected to each other with the airtight seal member and the fireproof seal member housed in the annular groove. The annular groove portion is open toward the other facing surface, and the airtight seal member accommodated therein is set so as to be pressed and deformed by the other facing surface. Is held in a hermetically sealed condition by the airtight seal member.
Further, by accommodating the fireproof seal member in a recessed portion of the annular groove, only the airtight seal member is pressed and deformed by the other facing surface to maintain the outer peripheral airtight state. As a result, if there is a problem with the airtight seal member such as a flaw that impairs the sealability or adhesion or drop of foreign matter, it is determined by the initial inspection that the airtight seal member has no sealability, and the defect of the airtight seal member can be surely found. Can be done.

In the seal structure of the connecting portion, it is preferable that the wire diameter of the fireproof seal member is set to be smaller than that of the airtight seal member.
By making the fire-resistant seal member an annular body that is thinner than the airtight seal member, both can be accommodated in the annular groove without making a mistake, and the width of the annular groove on the fire-resistant seal member side can be accommodated as much as the wire diameter is small. Since it can be made smaller, space can be saved.

In the seal structure of the connection portion, more preferably, the airtight seal member and the fireproof seal member are housed in the same one annular groove portion.
Only the airtight seal member is exposed from the open end of the annular groove portion, and the fireproof seal member is housed in a state of being pushed inward, so that the airtight seal member and the fireproof seal member are provided in one annular groove portion. To house together. In this case, one annular groove is provided on one of the opposing surfaces that form the connecting portion, and only the airtight sealing member and the fireproof sealing member are accommodated at the same time. Therefore, the manufacturing of the connecting portion and the sealing member Assembling is easy, and the space required for the seal structure can be made even smaller.
Further, when the inner diameter, the outer diameter, or the wire diameter of the fireproof seal member is different from the airtight seal member, the airtight seal member and the fireproof seal member are not confused, and There is no mistake in the mounting position of both.

In the seal structure of the connection portion, more preferably, the annular groove portion has a two-step structure of a first groove portion and a second groove portion having different depths,
The airtight seal member is housed in the shallowly formed first groove portion,
The fireproof seal member is housed in the deeply formed second groove.
By making the annular groove portion composed of first and second groove portions having different depths and accommodating the fireproof seal portion in the deeper second groove portion, the fireproof seal portion can be formed from the airtight seal member. Can be surely set back. Therefore, at the time of the initial inspection, it is possible to more reliably prevent the inconvenience that the fire-resistant seal portion interferes with the other facing surface to cause an unstable seal state.
Also in this case, since the fireproof seal member is different from the airtight seal member in either the inner diameter, the outer diameter, or the wire diameter, there is no confusion between the airtight seal member and the fireproof seal member, and the mounting of both There is no mistake in the position.

In the seal structure of the connecting portion, more preferably, of the pair of opposing side walls forming the annular groove, one opposing side wall is inclined so that its open end approaches the other opposing side wall,
That is, the fireproof seal member is accommodated near the one opposing side wall, and the airtight seal member is accommodated near the other opposing side wall.
By inclining one opposing side wall to the other opposing side wall side, the one opposing side wall and the bottom face form an acute angle, and the annular groove portion is opened mainly near the other opposing side wall. Become. As a result, in the fireproof seal member housed near the one of the opposing side walls, the open side is held in the retaining state by the one of the inclined opposing side walls.

In the seal structure of the connection portion, more preferably, the annular groove portion is provided separately from the first annular groove portion in which the airtight seal member is accommodated and the first annular groove portion and accommodates the fireproof seal member. And a second annular groove portion.
Since it is possible to visually check whether or not the seal members are respectively accommodated in the two first and second annular groove portions, it is possible to reliably prevent forgetting to accommodate the airtight seal member or the fireproof seal member in the annular groove portions. You can

In the seal structure of the connection part, more preferably, the connection part is a plug-in type connection part for inserting the inner cylinder into the outer cylinder in a retaining state,
The facing surface is an inner peripheral surface of the outer cylinder and an outer peripheral surface of the inner cylinder,
The annular groove portion is formed along the circumferential direction on either the inner peripheral surface of the outer cylinder or the outer peripheral surface of the inner cylinder.
When the inner cylinder is inserted into the outer cylinder in a state where the airtight seal member and the fireproof seal member are accommodated in the annular groove portion, the inner peripheral surface of the outer cylinder and the outer peripheral surface of the inner cylinder interfere with the other peripheral wall. Only the airtight seal member does not interfere with the fireproof seal member. Therefore, the inner cylinder can be inserted into the outer cylinder relatively smoothly, which facilitates the assembly of the plug-in type seal structure of the connecting portion.

In the seal structure of the connecting portion, the connecting portion is a press-type connecting portion that presses and fixes the facing end surfaces to each other while facing the flange portions that are outwardly projected from the connecting end portion of the tubular member.
The annular groove portion is formed concentrically with the tubular member on the opposing end surface of either one of the flange portions.
In the state where the airtight seal member and the fireproof seal member are accommodated in the annular groove portion, when the opposing end surfaces of the flange portion are connected to each other in a pressed state, the flange portions are screwed together while only the airtight seal member is pressed. Since it is fastened by means of a stopper or the like, the pressing force of a screw or the like can be reduced.

The present invention having the above-mentioned configuration has the following unique effects.
The fireproof seal member is housed in the recessed portion of the annular groove, and when the opposing surfaces are connected to each other, only the airtight seal member is pressed and deformed by the other opposing surface. If there is a mark, foreign matter is attached, or if the airtight seal member is not set, it is surely determined to have no sealability by the initial airtightness test. In this way, it is possible to surely find that the airtight seal member is defective.
In addition, if the wire diameter of the fireproof seal member is smaller than that of the airtight seal member, or if the airtight seal member and the fireproof seal member are housed in the same annular groove, the airtight seal member and the fireproof seal member Since the shape and dimensions of the seal member for use are different, they are not mistakenly recognized and the mounting position is not wrong.

It is sectional drawing which shows the connection state of the gas plug and connection joint which employ|adopted the seal structure of the connection part of the 1st Embodiment of this invention. It is a principal part expanded sectional view of FIG. 1, (A) has shown a part of gas plug before connecting with a connection joint, (B) has shown after connection. It is a principal part expanded sectional view which shows the connection state of the gas plug and connection joint which employ|adopted the seal structure of the connection part of the 2nd Embodiment of this invention. It is a principal part expanded sectional view of the gas plug which employ|adopted the sealing structure of the connection part of the 3rd Embodiment of this invention. It is a principal part expanded sectional view which shows the connection state of the gas plug and connection joint which employ|adopted the sealing structure of the connection part of the 4th Embodiment of this invention. It is a principal part expanded sectional view which shows the connection state of the flange parts of a gas plug and a connection cylinder part which employ|adopted the sealing structure of the connection part of the 5th Embodiment of this invention. It is a principal part expanded sectional view which shows the connection state of the flange parts of a gas plug and a connection cylinder part which employ|adopted the sealing structure of the connection part of the 6th Embodiment of this invention. It is a principal part expanded sectional view which shows the connection state of the flange parts of a gas plug and a connection cylinder part which employ|adopted the sealing structure of the connection part of the 7th Embodiment of this invention. It is a principal part expanded sectional view which shows the connection state of the flange parts of a gas plug and a connection cylinder part which employ|adopted the sealing structure of the connection part of the 8th Embodiment of this invention. It is an important section expanded sectional view of a gas stopper which adopted a seal of a connecting part of a 9th embodiment of the present invention, and (A) shows a part of gas stopper before being connected to a connection joint. , (B) shows after connection. It is a principal part expanded sectional view which shows the connection state of the gas plug and connection joint which employ|adopted the sealing structure of the connection part of the 10th Embodiment of this invention.

The best mode for carrying out the present invention will be described below with reference to the accompanying drawings.
As shown in FIG. 1, the seal structure of the connection portion of the first embodiment is the same as that of the gas outlet tube portion (1a) of the gas plug (G) and the gas intake tube portion (3) of the gas appliance (31). ) Is connected to the instrument connecting joint (2) which is screwed and connected by the female screw portion (23).
A gas inlet tube (1b) is provided on the upstream side of the gas storage section (24) of the gas stopper (G), and the gas inlet tube (1b) has a double-dot chain line in the same figure. As shown in, the flexible tube (30) is connected through the pipe joint (20). A gas flow path (4) is coaxially formed from an upstream end (right end in the drawing) of the gas inflow cylinder portion (1b) to a downstream end of the gas outflow cylinder portion (1a).

The appliance connection joint (2) is configured to be fitted onto the gas outflow tube portion (1a) in an airtight state and a retaining state, and one annular groove is formed on the outer peripheral surface of the gas outflow tube portion (1a). (10) is formed along the circumferential direction so as to open outward. Inside the annular groove (10), a rubber airtight O-ring (21) as an airtight seal member, and a fire-expandable rubber fire-resistant O-ring (22) having a large coefficient of thermal expansion as a fire-resistant seal member. Is housed.
As shown in FIG. 2(A), both the airtight O-ring (21) and the fire-resistant O-ring (22) have an inner diameter substantially corresponding to the minimum diameter formed by the bottom surface (10a) of the annular groove (10). And are held so as to be in close contact with the bottom surface (10a). The wire diameter of the airtight O-ring (21) is set to be equal to or larger than the depth of the annular groove portion (10), and the fireproof O-ring (22) has a smaller wire diameter than the airtight O-ring (21). Use a thin annular body. As a result, when it is fitted into the annular groove portion (10), as shown in the figure, the airtight O-ring (21) slightly protrudes from the open end of the annular groove portion (10), but the fireproof O-ring (21). The ring (22) is located behind the annular groove (10).
The fireproof O-ring (22) is located upstream of the airtight O-ring (21).

As described above, the gas outlet cylinder (1a) of the gas plug (G) containing the airtight O-ring (21) and the fireproof O-ring (22) in the annular groove (10) is connected to the gas intake cylinder. Insert it into the instrument connection joint (2) that is screw-connected to the part (3). In this case, the appliance connection joint (2) functions as an outer cylinder as an invention-specific matter, and the gas outflow cylinder portion (1a) functions as an inner cylinder.
Then, as shown in FIG. 2(B), the airtight O-ring (21) is pressed and deformed by the inner peripheral surface (2a) of the instrument connecting joint (2), and the inner peripheral surface of the instrument connecting joint (2). Since it comes into close contact with (2a), airtightness is secured between the instrument connection joint (2) and the gas outflow tube portion (1a). On the other hand, the fireproof O-ring (22) having a smaller wire diameter than the airtight O-ring (21) is housed in the annular groove (10) in a recessed state, and in a normal state, There is no contact with the inner peripheral surface (2a) of the instrument connection joint (2).

As a result, both the airtight O-ring (21) and the fireproof O-ring (22) interfere with the inner peripheral surface (2a) of the appliance connection joint (2), compared to the conventional plug-in type connection portion. Since the gas outflow cylinder part (1a) can be easily inserted into the appliance connection joint (2), the gas stopper (G) can be connected to the gas connection (2) via the appliance connection joint (2). When gas is flowed from the flexible tube (30) and the initial airtightness test is carried out in a state where it is connected to the inlet tube portion (3), if it is determined that there is no sealability, an airtight O-ring ( 21) There is a flaw, foreign matter such as dust is attached, and further, the O-ring (21) for airtightness is incomplete, such as forgetting to install the O-ring (21) for airtightness. You can certainly discover that there is.

FIG. 3 is an enlarged cross-sectional view of an essential part showing a connection state between the gas plug (G) adopting the seal structure of the connection part of the second embodiment and the instrument connection joint (2). In the embodiment, the bottom surface (10a) of the annular groove (10) has the second groove (12) for accommodating the fireproof O-ring (22) and the first groove (11) for accommodating the airtight O-ring (21). ) Is a two-stage structure formed deeper than. By accommodating the fireproof O-ring (22) in the second groove portion (12) formed deeper, the fireproof O-ring (22) is accommodated at a position deeper than the airtight O-ring (21). It is possible to more reliably prevent the inconvenience that the fireproof O-ring (22) interferes with the inner peripheral surface (2a) of the appliance connection joint (2) during the initial inspection to form an unstable sealed state. I can.

FIG. 4 is an enlarged cross-sectional view of a main part of the gas outflow cylinder portion (1a) of the gas plug (G) that employs the seal structure of the connection portion according to the third embodiment.
In this embodiment, of the pair of opposed side walls (10b) (10c) forming the annular groove (10), one of the opposed side walls (10c) located on the upstream side is the other opposed side wall (10c) located on the downstream side. By inclining to the side wall (10b) opposite, an acute angle portion is formed between the one side wall (10c) and the bottom surface (10a).
The refractory O-ring (22) is housed on the acute-angled portion side, so that the fire-resistant O-ring (22) is held in the retaining state by the one opposing side wall (10c) in the housed state, and the gas outflow cylinder is held. It is possible to prevent the inconvenience that the fireproof O-ring (22) interferes with the inner peripheral surface (2a) of the appliance connecting joint (2) when the portion (1a) is inserted into the appliance connecting joint (2).

The connection structure shown in each of the above embodiments relates to the sealing structure by having the airtight O-ring (21) and the fireproof O-ring (22) accommodated in the same one annular groove (10). Although the space can be made small, as in the fourth embodiment shown in FIG. 5, the first annular groove portion (13) for accommodating the airtight O-ring (21) and the refractory O are used as the annular groove portion. The second annular groove portion (14) for accommodating the ring (22) may be separately provided.
In this case, by providing the second annular groove portion (14) at the same depth as the first annular groove portion (13), the fire resistant O-ring (22) having a small wire diameter is provided in the second annular groove portion (14). It can be located deep inside. Further, it is possible to easily visually confirm whether or not the airtight O-ring (21) and the fireproof O-ring (22) are housed in the two first and second annular groove portions (13) and (14), respectively. Therefore, it is possible to reliably prevent forgetting to attach the airtight O-ring (21) and the fireproof O-ring (22).

In the fifth to eighth embodiments shown in FIGS. 6 to 9, the upstream facing end of the flange portion (15) radially extended to the upstream connecting end portion of the gas plug (G). The end surface (15a) and the opposing end surface (33a) of the flange portion (33) protruding at the downstream connecting end portion of the pipe connecting tubular portion (32) provided at the downstream end of the pipe are in contact with each other, and the screw This is a seal structure of a press-type connecting part that is pressed and fixed by a stopper (not shown) or the like.
Further, in the fifth to seventh embodiments shown in FIGS. 6 to 8, one annular groove portion (10) is provided on the facing end surface (15a) of the flange portion (15) of the gas plug (G). , Is formed so as to open downward concentrically with the gas flow path (40) of the gas plug (G), and the airtight O-ring (21) is provided on the outer side of the annular groove (10) near the inner wall (41). The fireproof O-ring (22) is housed near the wall (42).

In the fifth to seventh embodiments, the inner diameter of the airtight O-ring (21) is made substantially equal to the inner diameter of the annular groove (10), and the outer diameter of the fireproof O-ring (22) is set to the annular groove. The airtight O-ring (21) is in close contact with the inner wall (41) of the annular groove (10) by making the outer diameter of the annular groove (10) substantially coincide with the outer diameter of the annular groove (10). In the mode in which the outer wall 42 of FIG.
Also, by setting the wire diameter of the airtight O-ring (21) to be equal to or larger than the depth of the annular groove (10) and the wire diameter of the fireproof O-ring (22) smaller than that, both can be mistaken. It is not housed in the annular groove portion (10), and when the opposing end surface (15a) of the flange portion (15) and the opposing end surface (33a) of the flange portion (33) are brought into contact with each other and fastened with screws. The gas flow path (40) located inside the opposed end surfaces (15a) (33a) of the flange portions (15) (33) is kept airtight only by the airtight O-ring (21).
Further, when connecting the opposite end surfaces (15a) (33a) of the flange portions (15) (33) to each other in a pressed state, only the airtight O-ring (21) deforms by pressing, so that the fastening force of a screw or the like is applied. Can be made smaller.

In particular, in the sixth embodiment shown in FIG. 7, a step is formed on the bottom surface of the annular groove (10) so that the portion closer to the outer wall (42) is deeper than the portion closer to the inner wall (41). The O-ring (22) for refractory is housed inside the deeper portion of the outer wall (42) close to the O-ring (21) for air-tightness. Is surely stored in a recessed position. Therefore, it is possible to more reliably prevent the inconvenience that the fireproof O-ring (22) interferes with the inner peripheral surface (2a) of the appliance connection joint (2) during the initial inspection to form an unstable sealed state.

In the seventh embodiment shown in FIG. 8, the outer wall (42) of the annular groove (10) is inclined toward the inner wall (10b) side so that the outer wall (42) and the bottom surface (10a) are formed. The refractory O-ring (22) is housed in the acute angle portion formed between the two. The fireproof O-ring (22) in the housed state is held in the retaining state by the outer wall (42).

In the eighth embodiment shown in FIG. 9, an inner groove (16) for accommodating the airtight O-ring (21) and an outer groove for accommodating the fireproof O-ring (22) are provided as the annular groove (10). The side grooves (17) are separately provided. The inner groove (16) and the outer groove (17) are set to the same depth, and the airtight O-ring (21) and the fireproof O-ring (22) are connected to the inner groove (16) and the outer groove (17). By storing the fireproof O-ring (22) having a smaller wire diameter than the airtight O-ring (21), the fireproof O-ring (22) is housed deep inside the outer groove (17).
In this case, the airtight O-ring (21) is housed in the inner groove (16) in a substantially protruding state, and the fireproof O-ring (22) is housed in the bottom of the outer groove (17). You can easily check it with your eyes, so don't forget to attach the airtight O-ring (21) or fireproof O-ring (22).

In the ninth embodiment shown in FIG. 10, the gas outlet cylinder portion (1a) of the gas plug (G) adopted in the above-described first to fourth embodiments has an O-ring (21) for airtightness. ) And a fireproof O-ring (22) are attached, and (A) is an enlarged cross-sectional view of the gas outflow tube portion (1a) before being inserted into the instrument connection joint (2), and (B). Shows a state in which the gas outflow tube portion (1a) is inserted into the instrument connection joint (2).
One annular groove (10) is formed on the outer peripheral surface of the gas outlet cylinder (1a) so as to open outward, and the bottom surface (10a) of the annular groove (10) is the first groove (11). And a second groove portion (12) formed deeper than this has a two-stage structure. The airtight O-ring (21) is housed in the first groove (11) and the fireproof O-ring (22) is housed in the second groove (12).
The airtight O-ring (21) and the refractory O-ring (22) of this embodiment employ two ring bodies having the same inner diameter, outer diameter, and wire diameter. ) And larger than the diameter of the second groove portion (12). The wire diameter is set larger than the depth of the first groove portion (11).

When the airtight O-ring (21) of the above size is forcibly fitted into the first groove portion (11), the airtight O-ring (21) has a first inner peripheral edge portion as shown in FIG. 10(A). It is housed in such a manner that it is in close contact with the bottom of the first groove portion (11) and the outer peripheral edge portion projects from the open end of the annular groove portion (10). On the other hand, the fireproof O-ring (22) is housed in the second groove (12) in a recessed position in a loosely fitted state.

When the gas outlet cylinder (1a) is inserted into the instrument connecting joint (2) in this housed state, the airtight O-ring (21) protruding from the annular groove (10) causes the inner periphery of the instrument connecting joint (2). It is pressed and deformed on the surface (2a) and comes into close contact with the inner peripheral surface (2a) of the appliance connection joint (2), so the airtightness between the appliance connection joint (2) and the gas outflow tube portion (1a) is secured. To be done. On the other hand, the refractory O-ring (22) located deep inside the second groove (12) does not come into contact with the inner peripheral surface (2a) of the appliance connection joint (2). Therefore, when inserting the gas outflow cylinder portion (1a) into the instrument connection joint (2), it can be inserted relatively smoothly without disturbing, and if there is a flaw in the airtight seal member that impairs the sealing property. , Can be found by initial inspection.

The tenth embodiment shown in FIG. 11 also employs ring bodies having the same inner diameter, outer diameter, and wire diameter as the airtight O-ring (21) and the fireproof O-ring (22). A first annular groove portion (18) for accommodating the airtight O-ring (21) and a deeper portion than the first annular groove portion (18) are formed on the outer peripheral surface of the gas outflow cylinder portion (1a) of (G). A second annular groove (19) for accommodating the fireproof O-ring (22) is provided separately.
The inner diameters of the airtight O-ring (21) and the fireproof O-ring (22) are set to be smaller than the diameter of the first annular groove portion (18) and larger than the diameter of the second annular groove portion (19), and the wire diameter is The depth is set larger than the depth of the first annular groove portion (18). As a result, the airtight O-ring (21) is in a storage mode in which it is in close contact with the bottom of the first annular groove (18) and projects from the open end thereof, and the fireproof O-ring (22) is in the second annular groove (19). ) It becomes the accommodation mode which is located in the inner part of the inside in a loose fitting state.

When the gas outflow tube portion (1a) is inserted into the instrument connection joint (2) while the airtight O-ring (21) and the fireproof O-ring (22) are accommodated, as shown in the figure, the first annular shape is obtained. The airtight O-ring (21) projecting from the groove (18) is pressed and deformed by the inner peripheral surface (2a) of the instrument connecting joint (2), and is attached to the inner peripheral surface (2a) of the instrument connecting joint (2). The close contact can ensure the airtightness between the appliance connection joint (2) and the gas outflow tube portion (1a). On the other hand, the fireproof O-ring (22), which is recessed in the second annular groove (19), does not come into contact with the inner peripheral surface (2a) of the appliance connection joint (2).

(10) ・・・・・ Annular groove
(21)・・・・・・O-ring for airtightness (sealing member for airtightness)
(22)・・・・・・Fireproof O-ring (fireproof seal member)

Claims (8)

In the seal structure of the connecting portion, which keeps the facing surfaces facing each other in the connected state in a hermetically sealed state,
On one of the facing surfaces, an annular groove portion that opens toward the other facing surface is formed along the entire circumferential direction,
In the annular groove portion, an annular airtight seal member and an annular fireproof seal member made of a heat-expandable material are housed,
The airtight seal member is pressed and deformed by the other facing surface in a state of being accommodated in the annular groove portion when the connecting portions are connected to each other,
The seal structure for a connecting portion is characterized in that the fireproof seal member is housed at a position deeper than an open end of the annular groove portion. In the seal structure of the connection part according to claim 1,
The wire structure of the fireproof seal member is set to be smaller than that of the airtight seal member. The seal structure for a connecting portion according to claim 1 or 2,
A seal structure for a connecting portion, wherein the airtight seal member and the fireproof seal member are housed in the same one annular groove. In the seal structure of the connection part according to claim 3,
The annular groove portion has a two-step structure of a first groove portion and a second groove portion having different depths,
The airtight seal member is housed in the shallowly formed first groove portion,
A seal structure for a connecting portion, characterized in that the refractory seal member is housed in a deeply formed second groove portion. In the seal structure of the connection part according to claim 3,
Of the pair of opposing side walls forming the annular groove portion, one opposing side wall is inclined so that its open end approaches the other opposing side wall,
A seal structure for a connecting portion, wherein the fireproof seal member is accommodated near the one opposing side wall, and the airtight seal member is accommodated near the other opposing side wall. The seal structure for a connecting portion according to claim 1 or 2,
The annular groove portion includes a first annular groove portion that accommodates the airtight seal member and a second annular groove portion that is provided separately from the first annular groove portion and that accommodates a fireproof seal member. Sealing structure for the connection part. The seal structure for a connecting portion according to any one of claims 1 to 6,
The connecting portion is a plug-in type connecting portion for inserting the inner cylinder into the outer cylinder in a retaining state,
The facing surface is an inner peripheral surface of the outer cylinder and an outer peripheral surface of the inner cylinder,
The sealing structure for a connecting portion, wherein the annular groove portion is formed along the circumferential direction on either the inner peripheral surface of the outer cylinder or the outer peripheral surface of the inner cylinder. The seal structure for a connecting portion according to any one of claims 1 to 6,
The connecting portion is a pressing-type connecting portion that causes the flange portions that are outwardly projected from the connecting end portion of the tubular member to face each other, and that presses and fixes the facing end surfaces to each other,
The sealing structure for a connecting portion, wherein the annular groove portion is formed concentrically with the tubular member on the opposing end surface of one of the flange portions.

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