JP2003139597A - Piping structure for gas meter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the replacement of a gas meter M possible to be completed only by outdoor work, in relation to a piping structure for a gas meter wherein a gas fed into a meter body 10 from a lead-in pipe through a gas discharge pipe 31 is fed into an indoor pipe, a main valve body for opening and closing the passage of the gas is installed in a gas introducing pipe for connecting the lead-in pipe, and the discharge pipe 31 is provided with a gas pressure inspecting hole 43 communicating with the passage thereof in a manner capable of opening and closing it. SOLUTION: In the discharge pipe 31, an auxiliary valve 1 for opening and closing its gas passage is rotatably installed. In the auxiliary valve 1, communication holes 17 and 18 respectively opened to three positions of the circumferential surface of its body part are formed. In a state where a passage 39 in the discharge pipe 31 is shut off by the auxiliary valve 1, one of the open ends of the communication holes is opened to the inspecting hole 43 and another one is so set as to be opened to the upstream side of the auxiliary valve 1 in the discharge pipe 39.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas meter piping structure, and more particularly to a structure of a gas meter installed outdoors for measuring the amount of gas used at home and a piping connected to the gas meter.

[0002]

2. Description of the Related Art In general, the use of gas at home is provided between a lead-in pipe (2) extended from an underground main pipe and a feed pipe (3) for feeding gas into each home. A gas meter (M) for measuring the quantity is provided and these are installed outdoors.

This type of gas meter (M) is, as shown in FIG. 5, a meter main body (10) having a built-in measuring instrument and the like, and a gas installed in parallel at the upper end of the meter main body (10). It is composed of an inlet port (12) and a gas outlet port (13), and one end of a substantially U-shaped gas inlet pipe (21) is connected to the gas inlet port (12). In the (13), the gas inflow pipe (21)
A gas outflow pipe (31) having the same shape as that of is connected. And, the other end (inflow side end) of the gas inflow pipe (21) is connected to the lead-in pipe (2) through a joint (22), and the other end of the gas outflow pipe (31) ( At the outlet end), the feed pipe (3)
Are connected via a joint (32). As a result, the intake pipe (2) and the feed pipe (3) are connected to the gas inlet pipe (21) and the gas meter.
(M), and further connected via the gas outflow pipe (31).

In addition, the gas inflow pipe (21) is connected to the gas inflow pipe (21).
A plug main body (23) for opening and closing the inner flow passage is provided, and an inspection hole (not shown) communicating with the inner flow passage is formed in the gas outflow pipe (31). This inspection hole is connected to the pressure Keiga for measuring the pressure of the gas flowing in the gas passage of the gas outflow pipe (31), but is closed by the stopper (5) except during measurement.

The gas meter (M) needs to be replaced at a predetermined cycle. During the replacement work, by closing the plug main body (23), the gas supplied from the lead-in pipe (2) is blocked upstream of the plug main body (23). As a result, even if the gas meter (M) is removed, there is no risk of the gas leaking to the outside from the upstream side of the gas inflow pipe (21).

[0006]

[Problems to be Solved by the Invention]
By closing 3), even if the gas meter (M) is removed, gas does not leak from the intake pipe (2), but the inflow side end of the gas outflow pipe (31) is open. However, there is a disadvantage that external air flows into the gas outflow pipe (31) and the feed pipe (3). Therefore, the gas meter (M)
After the replacement, the air bleeding work must be performed in the meter body (10), the feed pipe (3), and further the indoor pipe (4) following the feed pipe (3).

[0007] Whether or not the air bleeding has been completed must be confirmed by igniting various gas appliances (40) to which the indoor side pipe (4) is connected. It is troublesome because it is necessary to enter the installation place of the device (40). Furthermore, there is also a problem that it is not possible to confirm the completion of air bleeding in the gas appliance (40) when the family member is not present.

According to the present invention, "a meter body having a gas inlet and a gas outlet, a gas inlet pipe connected to the gas inlet, and a gas outlet connected to the gas outlet. A pipe, a lead-in pipe connected to the inflow side end of the gas inflow pipe and drawing gas into the meter main body, and a gas inside the meter main body connected to the outflow side end of the gas outflow pipe. The gas inflow pipe is provided with a plug main body for opening and closing the flow passage, and the gas outflow pipe is opened and closed with a gas pressure inspection hole communicating with the flow passage. It is an object of the present invention to make it possible to complete the replacement of the gas meter only in the outdoor work in the “provided gas meter piping structure”.

[0009]

[Means for Solving the Problems] * 1 The technical means of the present invention for solving the above-mentioned problems is that "in the gas outflow pipe, an auxiliary plug for opening and closing the gas passage is rotatable. Communication holes that are provided in the auxiliary plug and are opened at three locations on the peripheral surface of the body, respectively, and the communication is performed with the auxiliary plug blocking the flow path in the gas outflow pipe. Of the open ends of the holes, one is open to the gas pressure inspection hole and one is open to the upstream side of the auxiliary plug in the gas outflow pipe ”. .

The above technical means operates as follows. When the gas is used, two of the three open ends of the communication holes provided in the auxiliary plug are set to the postures in which they are opened to the flow path of the gas outflow pipe, respectively. As a result, the gas sent from the intake pipe is sent to the feed pipe through the meter body, through the communication hole in the auxiliary plug of the gas outflow pipe. At this time, it is assumed that the gas pressure inspection hole is closed. Then, when replacing the gas meter, before removing the meter body, by closing the main plug provided in the gas inflow pipe and the auxiliary plug provided in the gas outflow pipe, the plug of the gas inflow pipe is Upstream of the subject,
Also, the flow path to the downstream side of the auxiliary plug in the gas outflow pipe is blocked. As a result, the gas sent from the intake pipe does not leak outside, and the outside air does not enter the inside of the feed pipe.

After the gas meter is replaced, the gas pressure inspection hole is opened and the air vent is connected. Then, the posture of the auxiliary plug is adjusted so that the gas pressure inspection hole and the flow path on the upstream side of the auxiliary plug are connected by the communication hole while keeping the flow path on the downstream side of the auxiliary plug blocked. Set. After that, when the main body of the stopper is opened, the gas from the intake pipe is sent into the meter body, and the air in the meter body is pushed by the gas and escapes to the outside from the air vent. It is possible to confirm that the air bleeding inside the meter body has been completed based on the smell of gas leaking outside from the air bleeding tool and the presence or absence of ignition.

* In the paragraph 1 of paragraph 2, "the communicating hole communicates with the first passage which is orthogonal to the rotation axis of the auxiliary plug and the second passage which is orthogonal to the first passage. And the passage is formed into a substantially T-shape ”, the auxiliary plug 9 is opened from the opened state in which the first passage is located along the flow path of the gas outflow pipe.
By turning it by 0 degree, one of the first passages is opened to the gas pressure inspection hole, and the second passage is opened at the air outlet position where the second passage is opened to the upstream side of the auxiliary stopper in the gas outlet pipe. The posture of can be set.

* 3 In paragraphs 1 and 2, "a part of the peripheral wall of the gas outlet pipe is provided with an opening hole for inserting the auxiliary plug in a direction perpendicular to the axis of the flow path of the gas outlet pipe. A concave portion for rotatably receiving the insertion end of the auxiliary plug is formed at a predetermined position of the inner wall of the gas outflow pipe which penetrates and faces the open hole, and the auxiliary plug is rotated. The operation part is
The opening hole is provided so as to be embedded in the opening hole, and the opening hole is closed in an airtight state by a closing cap. '
After removing the closing cap, the auxiliary plug may be rotated by operating the rotation operation portion of the auxiliary plug. Since the rotating operation portion is provided so as to be embedded in the open hole formed in the peripheral wall of the gas outflow pipe, it is difficult to rotate it by hand, and a special tool is required. Further, if the auxiliary cap can be removed only by a dedicated tool, the rotation of the auxiliary plug becomes even more difficult.

* 4 In each of the above items, "the auxiliary plug is formed in a cylindrical shape, and a groove portion for a tool is provided on the top surface of one of the auxiliary plugs, and the forming direction of the groove portion is Among the communication holes, the same direction as the formation direction of the passage for opening the flow path of the gas outflow pipe is set. ”Since the auxiliary plug has a cylindrical shape, the auxiliary plug is inserted into the gas outflow pipe. The opening hole for receiving and the recess for receiving the inserted auxiliary plug can be formed in the same size. Also, by inserting the tool into the groove formed on one of the top surfaces of the auxiliary plug and rotating the tool, the auxiliary plug can be rotated in the gas outflow pipe. Further, since the forming direction of the groove is made to coincide with the forming direction of the passage for opening the flow passage of the gas outflow pipe among the communication holes formed in the body of the gas outflow pipe, the flow passage is oriented in the direction of the groove. The open state and closed state of can be easily confirmed.

[0015]

The present invention, having the above-mentioned structure, has the following unique effects. Air bleeding work after replacing the gas meter
It is only necessary to bleed the air inside the meter body, which can be easily done from the gas pressure inspection hole provided in the gas outflow pipe and the completion of gas bleeding can be confirmed. The gas meter replacement work can be completed with. Therefore, it is possible to save the trouble of going up to the equipment installation place in each home and checking the air release,
Since the gas meter replacement work can be performed even when the householder is absent, the gas meter replacement becomes easy, the efficiency of the replacement work is improved, and the time required for the work is shortened.

In addition to the above effects, in the second item, the auxiliary plug can be opened and closed by rotating the auxiliary plug by 90 degrees, and the auxiliary plug can be easily rotated to the posture at the time of bleeding. Therefore, there is an effect that it is easy to use. In addition to the above-mentioned effects, the third aspect has an effect that there is no inconvenience that the auxiliary plug is inadvertently rotated by mischief or the like.

Further, in the item (4), since the auxiliary plug is formed into a cylindrical shape and the groove portion is provided as the rotating operation portion, the auxiliary plug and the gas outflow pipe for housing the auxiliary plug can be easily manufactured. Further, since the posture of the auxiliary plug can be confirmed by the direction of the groove portion, the usability is further improved.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the embodiments of the present invention described above will be described in detail with reference to the drawings. FIG. 1 shows a front view of a gas meter according to an embodiment of the present invention, and FIG. 2 shows a gas outlet pipe (3
It is an expanded side view of only 1), and shows the state which removed the closure cap (15) of FIG. And FIG. 3 shows an auxiliary plug
It is an expanded sectional view showing a state of (1).

The gas meter according to the embodiment of the present invention is similar to the conventional one, and a meter body (10) and a gas inlet port (12) and a gas outlet port (1) provided in parallel on the upper surface thereof.
3) and a gas inlet pipe (21) formed in a straight line is connected above the gas inlet port (12), and the gas inlet pipe (21) has The main body (23) for opening and closing the flow path, the operation part (24) is the meter body (10)
It is provided so as to project to the front side of the.

On the other hand, a straight gas outflow pipe (31) is connected above the gas outlet (13). The gas outflow pipe (31), a gas pressure inspection plug (41) for connecting a pressure gauge (not shown) for measuring the pressure of the gas flowing in the flow path of the gas outflow pipe (31), The gas outflow pipe (31)
The operation part of the plug main body (23) so as to communicate with the flow path (39) of
It projects in the same direction as (24). Gas Pressure Check Plug (41)
Is to maintain the valve closed state by connecting the pressure gauge unless the valve body (not shown) incorporated therein is opened. In this valve closed state, the valve state shown in FIG. The protective cap (42) so that the gas pressure test plug (4
It is attached to the base end of 1) by screwing.

On the peripheral wall of the gas outflow pipe (31) which is moved to the outside (right side in FIG. 1) of the meter body (10) by 90 degrees in the circumferential direction from the protruding position of the gas pressure inspection plug (41). As shown in FIG. 3, the through hole (3
0) is formed.

This through hole (30) is a passage for the gas outflow pipe (31).
It is for inserting an auxiliary plug (1) for opening and closing (39), and a closing cap (15) described later is screwed to the open end of the through hole (30) as shown in the figure. The female screw portion (33) for forming the female screw portion (33) is formed, and the screwless tubular portion (37) is extended further to the inner side than the base end portion of the female screw portion (33). A step portion (34) having a predetermined width extends inwardly from the base end portion of the screwless cylinder portion (37), and the through hole (30) on the back side of the step portion (34) is It is set to match the inner diameter of the step (34). And, at a predetermined position of the inner wall of the gas outflow pipe (31) located at a position facing the position where the through hole (30) is formed, a circular recess (of a size substantially corresponding to the inner diameter of the stepped portion (34) ( 20) is formed, and the insertion end of the auxiliary plug (1) is rotatably accommodated in the recess (20).

The auxiliary plug (1) is a stepped portion (34) of the through hole (30).
Is formed into a cylindrical body having a diameter that can be inserted from the inner peripheral edge portion of the gas outlet pipe (31) at the insertion end of the auxiliary plug (1).
Fit in the recess (20) of the. As a result, the auxiliary plug (1) is placed in the auxiliary plug housing (38) formed in the gas outflow pipe (31) in a direction perpendicular to the flow path (39) in the gas outflow pipe (31). It is rotatably accommodated while being inserted and fitted in the recess (20).

As shown in FIG. 4, the body portion of the auxiliary plug (1) has a first passage (17) passing through the center of the auxiliary plug (1).
And a second passageway (27) communicating with the central portion of the first passageway (17) and positioned at a right angle to the axis of the first passageway (17) form a substantially T-shaped communication hole. . This allows the auxiliary plug (1)
In the body part, three open ends that are continuous with the communication holes are formed. The diameter of the first passage (17) is slightly smaller than the diameter of the flow passage (39), and the diameter of the second passage (27) is (41).
It is assumed that the diameter is slightly smaller than the diameter of the inner channel (43).

The auxiliary plug (1) located on the open end side of the through hole (30) in a state where the auxiliary plug (1) is inserted into the gas outflow pipe (31) from the through hole (30). ) On the top surface on the one end side, a rotation operation part (14) which is a flat cylindrical body is integrally formed so as to protrude, and passes through the center of the top surface of the rotation operation part (14). Further, the groove portion (14a) as a tool corresponding portion is provided with the first
It is formed in the same direction as the communication direction of the passage (17). still,
The axial length of the auxiliary plug (1) and the protruding height of the turning operation part (14) are set to predetermined dimensions so that the turning operation part (14) is also located in the through hole (30). Be present. With the auxiliary plug (1) accommodated in the through hole (30), the open end of the through hole (30) is closed by the closing cap (15).

The closure cap (15) has a head portion (15a) formed to have a diameter larger than that of the through hole (30), and a screw shaft portion () which can be screwed into the female screw portion (33). 15b) is a metal screw stopper consisting of a screw shaft portion (15b) and a tubular portion (15c) having a diameter smaller than that of the screw shaft portion (15b) at the tip side of the screw shaft portion (15b).
It is extended by the length of (37) and the cylindrical part (15
An annular packing (16) is provided on the outer peripheral portion of c).

After accommodating the auxiliary plug (1) in the through hole (30), the screw shaft portion (15b) of the closing cap (15) is attached to the female screw portion (33).
When screwed in, the annular packing (16) comes into close contact with the inner surface of the screw-free tubular portion (37), resulting in a closure cap.
(15) is a mode in which the through hole (30) is closed in an airtight state. The screw shaft portion (15b) of the closing cap (15) is set to have a structure such that the tightening degree cannot be easily loosened without using a tool.

As shown in FIG. 1, the inflow side end which is the upper end of the gas inflow pipe (21) has a pair of elbow pipes (25) and a connecting pipe (26) connecting them, The outflow side end, which is connected to the lead-in pipe (2) and is the upper end of the gas outflow pipe (31), similarly has a pair of elbow pipe through holes (30) and a connecting pipe (36) connecting these. Shall be connected to the feed pipe (3) via.

In the piping structure of the gas meter according to this embodiment, during normal use of the gas, the auxiliary plug (1) is rotated in the auxiliary plug accommodating portion (38), as shown in FIG. 4 (a). Thus, both ends of the first passage (17) are opened to the flow passage (39) of the gas outflow pipe (31) and the second passage (27) is closed by the peripheral wall of the auxiliary plug accommodating portion (38). The posture is set to.

In this posture, the gas sent from the lead-in pipe (2) passes through the meter main body (10) and the gas outflow pipe.
It is sent to the feed pipe (3) through the first passage (17) of the auxiliary plug (1).

FIG. 4 (b) shows the auxiliary plug (1) from the state of (a).
2 shows a second posture in which the first passage (17) is opened to the flow passage (39) of the gas outlet pipe (31) and the second passage ( 27) is open to the flow path (43) side of the gas pressure inspection plug (41). In this posture, a dynamic pressure of the gas flowing in the pipe can be measured by connecting a pressure gauge (not shown) to the gas pressure inspection plug (41).

FIG. 4 (c) shows the auxiliary plug (1) from the state of (b).
Shows a third posture in which the is rotated clockwise by 90 degrees. In this posture, one end of the first passage (17) is opened to the flow path (43) side of the gas pressure inspection plug (41). And the other end is closed by the peripheral wall of the auxiliary plug accommodating portion (38).
(27) is set to open downstream of the auxiliary plug (1) in the flow path (39) of the gas outflow pipe (31). In this posture, the flow path (39) of the gas outflow pipe (31) is blocked by the auxiliary plug (1). Further, by connecting a pipe pressure gauge to the gas pressure inspection plug (41), it is possible to inspect gas leakage in the pipe on the downstream side of the auxiliary plug (1).

FIG. 4D shows the auxiliary plug (1) from the state of (c).
Is shown in a fourth position in which the first passage (17) is opened to the flow path (43) side of the gas pressure inspection plug (41) and the other position is obtained by rotating the other 180 degrees. The end is the auxiliary plug housing (3
The second passage (27) is closed by the peripheral wall of 8), and is open to the upstream side of the flow passage (39) of the gas outflow pipe (31) with respect to the auxiliary plug (1). In this position, the auxiliary plug (1)
The gas sent to is sent to the gas pressure inspection plug (41).

Of the first to fourth postures described above, the first
And the second position, the flow path (39) of the gas outflow pipe (31) is opened, and the gas outflow pipe (31) is opened in the third and fourth positions.
The flow channel (39) is blocked by the auxiliary plug (1). The groove portion (14a) of the turning operation portion (14) is positioned vertically when the flow path (39) of the gas outflow pipe (31) is open.

Next, the procedure for replacing the gas meter will be described. Before removing the gas meter, the operating part (24) of the plug main body (23) is operated to close the plug main body (23). As a result, the gas sent from the intake pipe (2) is
Of the (21), it is blocked upstream of the main plug (23).

At the same time, the closing cap (15) is removed by using a tool and is formed on the top surface of the rotary operation part (14) of the auxiliary plug (1) built in the through hole (30). Groove (14
Engage a) with a flat tool (not shown) such as a coin. In the gas flow state, the auxiliary plug (1) is in the state of (a) of FIG. 4, and the groove portion (14a) is, as described above,
Since it is set to be vertically positioned, the auxiliary plug (1) is rotated 90 degrees counterclockwise so that it is positioned horizontally. As a result, the auxiliary plug (1) is not
The auxiliary plug (1) is rotated by 0 degree, and the auxiliary plug (1) is brought into the state of (c) of FIG. 4, and the flow path (39) of the gas outflow pipe (31) is blocked by the auxiliary plug (1).

After that, the gas inlet port (1
2) Remove the gas outlet (13) from the gas inlet pipe (21) and the gas outlet pipe (31) and replace the gas meter (M). After replacing the gas meter (M), inside the meter body (10) of the new gas meter (M), as well as the gas inlet (12) and gas outlet (13)
To the plug main body (23) of the gas inflow pipe (21) and the auxiliary plug (1) of the gas outflow pipe (31) are filled with air. Therefore, the air bleeding work of this portion is performed.

In order to perform the air bleeding operation, the protective cap (42) of the gas pressure inspection plug (41) is removed and an air bleeding socket (not shown) is connected to the gas pressure inspection plug (41). . Then, the auxiliary plug (1) is rotated to set it to the fourth posture shown in (d) of FIG. 4, and the plug main body (23) is rotated in the opening direction to set the inside of the meter body (10). Send in gas.

The air in the meter body (10) is pushed by the sent gas, and the second passage (27) to the first passage of the auxiliary plug (1) is pushed.
It flows into the flow path (43) of the gas pressure inspection plug (41) via the (17). A gas rubber tube (not shown) is connected to the air bleeding socket, and when the gas leaking from the rubber tube changes from air to gas, the auxiliary plug (1) is rotated 90 degrees counterclockwise. It is rotated to return to the first posture.

This completes the bleeding of the air in the meter body (10). The fact that the air inside the meter body (10) has escaped
The smell of gas leaking from the tip of the gas rubber tube in the previous period,
It can be confirmed by ignition to the burner or empirical passage of time.

As described above, the air bleeding work required after the replacement work of the gas meter (M) may be carried out within the gas meter (M) and only within a partial range of the gas inflow pipe (21) and the gas outflow pipe (31). Therefore, the gas meter (M) replacement and the air bleeding confirmation work can be performed only outdoors. Therefore, even when the occupant is absent, the gas meter (M) can be replaced easily and quickly.

The material of the auxiliary plug (1) is resin,
Any of rubber and metal can be adopted, and the shape of the auxiliary plug (1) is not limited to a cylindrical shape, and may be a truncated cone shape.

Further, opening and closing of the flow path (39) of the gas outflow pipe (31)
It can be confirmed by the direction of the groove (14a) provided in the rotation operation part (14) of the auxiliary plug (1), but the position of the second passage (27) with respect to the first passage (17) can also be confirmed. , 2nd passage (27)
Needless to say, a mark such as a protrusion may be provided at a predetermined position of the rotary operation part (14) corresponding to the forming direction of the.

[Brief description of drawings]

FIG. 1 is a front view showing a piping structure of a gas meter according to an embodiment of the present invention.

FIG. 2 is a side view of a gas outflow pipe connected to the gas meter according to the embodiment of the present invention.

FIG. 3 is an enlarged sectional view of an essential part showing a state in which an auxiliary plug is arranged in a gas outflow pipe connected to the gas meter according to the embodiment of the present invention.

FIG. 4 is a cross-sectional view showing a state of each posture due to the rotation of the auxiliary plug.

FIG. 5 is a front view showing a piping structure of a conventional gas meter.

[Explanation of symbols]

(1) ・ ・ ・ Auxiliary stopper (10) ・ ・ ・ Meter body (12) ・ ・ ・ Gas inlet (13) ・ ・ ・ Gas outlet (2) ... Retracting pipe (21) ・ ・ ・ Gas inlet pipe (23) ・ ・ ・ Mainly stopper (3) Feed tube (31) ・ ・ ・ Gas outflow pipe

Claims (4)

[Claims] 1. A meter body having a gas inlet and a gas outlet, a gas inlet pipe connected to the gas inlet, and a gas outlet pipe connected to the gas outlet. A lead-in pipe connected to the inflow side end of the gas inflow pipe and drawing gas into the meter body, and a feed pipe connected to the outflow-side end of the gas outflow pipe and sending the gas in the meter body indoors. In the gas inflow pipe, a plug main body for opening and closing the flow passage is provided, and in the gas outflow pipe, a gas pressure inspection hole communicating with the flow passage is provided so as to be openable and closable. In the piping structure of the gas meter, an auxiliary plug for opening and closing the gas flow path is rotatably provided in the gas outflow pipe, and the auxiliary plug has three locations on the circumferential surface of the body. Communication holes that open to each of the With the auxiliary plug blocking the flow path in the gas outflow pipe, one of the open ends of the communication hole is opened to the gas pressure inspection hole, and one is the auxiliary plug in the gas outflow pipe. A piping structure of a gas meter, which is set so as to open to an upstream side of the gas meter. 2. The pipe structure for a gas meter according to claim 1, wherein the communication hole has a first passage penetrating in a direction perpendicular to a rotation axis of the auxiliary plug and a right angle with respect to the first passage. The piping structure of the gas meter formed in a substantially T shape from the second passage communicating in the direction. 3. The gas meter piping structure according to claim 1, wherein the auxiliary plug is inserted into a part of a peripheral wall of the gas outflow pipe in a direction perpendicular to an axis of a flow path of the gas outflow pipe. And a recess for rotatably receiving the insertion end of the auxiliary plug is formed at a predetermined position on the inner wall of the gas outflow pipe facing the opening. The rotating operation part is provided so as to be embedded in the open hole, and the open hole is closed in an airtight state by a closing cap. 4. The pipe structure for a gas meter according to claim 1, wherein the auxiliary plug is formed in a cylindrical shape, and a groove portion corresponding to a tool is provided on one top surface of the auxiliary plug. The gas meter piping structure is characterized in that the forming direction of the groove is set to be the same as the forming direction of a passage that opens the flow path of the gas outflow pipe in the communication hole.