JPH06170209A - Method for circulating gas in autoclave - Google Patents

Abstract

PURPOSE:To obtain products of uniform and high quality by passing gas sent by fans at gas suction ports through both outer ventilation paths which are divided and are in the opposite direction to each other, causing the gas to meet each other at a gas blowing port and to flow in an inner ventilation path and properly dividing the gas among gas suction ports to circulate it. CONSTITUTION:As for a method for circulating gas in an autoclave, outer ventilation paths 11a, 11b are formed between an inner wall 2a and an air duct wall 10 of an autoclave and an inner ventilation path 12 is formed inside the air duct wall 10; plural gas suction ports 13 are provided at constant intervals in series in the upper part of the air duct wall 10 and plural gas blowing ports 14 are provided in the lower part corresponding to the gas suction ports 13; fans 15 are arranged each in the plural gas suction ports 13; and the outer ventilation paths 11a, 11b are divided every adjacent fans 15 by partition members 16 in the longitudinal direction of a vessel A to form the outer ventilation paths 11a, 11b. And gas sent by each fan 15 is passed through the outer ventilation paths 11a, 11b which are divided and are in the opposite direction to each other and meets each other at the gas blowing ports 14 to flow in the inner ventilation path 12 and the gas is properly divided among plural gas suction ports 13 to be circulated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to composite materials such as fiber reinforced plastics (FRP) used for aircraft, space equipment, industrial equipment, building materials, and laminated glass.
The present invention relates to a method of circulating the gas when pressure-heating and cooling in an autoclave to perform bonding or adhesive molding.

[0002]

2. Description of the Related Art Conventionally, as a method of circulating a gas for pressurizing and heating a material 1 to be bonded or adhesively molded in an autoclave, for example, a method in which a gas is circulated in a horizontal direction as described in Japanese Patent Laid-Open No. 14730/1990. Are known. It is also known to circulate the gas vertically from below to above and further downward.

The former gas circulation method is disclosed in JP-A-2-14.
As shown in FIG. 1 on page 7 of Japanese Patent Publication No. 730, the gas flow blown by the fan drive device is swirled by the guide vanes from the outer ventilation passage formed between the inner wall of the container and the wind tunnel wall. After that, the inner wall of the door facing this is reversed, and the reversed flow flows while swirling in the wind tunnel, and the gas is horizontally circulated to the outer ventilation passage through the heating / cooling means.

In the latter gas circulation method, as shown in FIG. 5, an outer ventilation passage 11 is formed between the container inner wall 2a and the rectangular wind tunnel wall 10, and an inner ventilation passage 12 is formed inside the wind tunnel wall 10. Then
A plurality of gas inlets 13 are provided in series at an upper portion of the wind tunnel wall 10 at regular intervals, and a plurality of gas outlets 14 are provided at a lower portion in correspondence with the gas inlets 13 and the plurality of gas inlets 13 are provided. A fan 15 is disposed in each of the fans 13, and the fan causes the gas to flow vertically from the lower side to the upper side and further to the lower side from the outer ventilation passage 11 to the gas outlet 14 to the inner ventilation passage 12 to the gas inlet 13. It is configured to flow and circulate in a plurality of gas circulation zones Ca. A set of a heater 18a and a cooler 18b are provided on the outside ventilation passage 11, and a temperature sensor 23 is further provided at a position substantially in the center of the gas circulation zone Ca to control the heater 18a or the cooler 18b to control the gas flow. The temperature is controlled.

[0005]

However, in the former gas circulation method, the gas flow blown by the fan driving device is designed to flow horizontally in the longitudinal direction of the container while swirling in the wind tunnel. Therefore, if the materials to be glued or adhesively molded are placed side by side along the length of the container (generally this way), the heated gas first touches the material on the inlet side, To remove the heat, then the second material is touched to remove the heat, which in turn removes the heat. Therefore, the heating temperature of the material located on the inlet side and the heating of the material located on the back side of the container There is a difference in temperature. As a result, the difference in temperature at which the material at each position is heated adversely affects the adhesiveness or adhesive moldability of the product, resulting in a quality problem.

Further, in the latter gas circulation method, as shown in FIG. 5, a temperature sensor 23 is provided at a substantially central position of the gas circulation zone Ca, and the value of the temperature sensor 23 of the material 1 exists at each position. It is a typical value, and since the gas is circulated independently by each fan 15, the pressure vessel A
If the material 1 accommodated in the container has a difference in size, quantity, placement, thickness of the article, material difference, etc., when the material 1 at each position is heated, a temperature difference occurs and the adhesiveness of the material 1 is increased. Alternatively, the adhesive moldability is adversely affected and there is a problem in quality. Further, when the material 1 contained in the pressure vessel A is the same, even if the material 1 at each position has a temperature difference, the temperature of the gas in each gas circulation zone Ca cannot be controlled, and therefore the same material is used. 1
Are adhered or adhesively molded with the temperature difference still occurring, resulting in variations in the adhesiveness or adhesive moldability of the product, which is a quality problem.

The present invention was developed for the purpose of solving the above-mentioned problems.

[0008]

As shown in FIG. 1 and FIG. 3 (a), the present invention provides an autoclave in which a material 1 is heated and cooled under pressure in a pressure vessel A to be bonded or adhesively molded. An outer ventilation passage is formed between the pressure vessel inner wall 2a and the wind tunnel wall 10, and an inner ventilation passage 12 is formed inside the wind tunnel wall 10, and a plurality of gas suction ports 13 are provided at a constant interval above the wind tunnel wall 10. In series with a plurality of gas outlets 1 in the lower part
4 are provided corresponding to the gas inlets, and fans 15 are arranged at the plurality of gas inlets 13 and the external ventilation passages are arranged in the longitudinal direction of the container 2 by the partitioning member 16 for each adjacent fan. The outer ventilation passages 11a and 11b are separated from each other, and the gas blown by the respective fans 15 passes through the divided outer ventilation passages 11a and 11b in the opposite directions to be exchanged with each other at the gas outlet 14. The gas flows into the ventilation passage 12, is appropriately divided into a plurality of gas suction ports 13, and is circulated.

Further, as shown in FIGS. 2 and 3B,
In the autoclave in which the material 1 is pressurized and heated in the pressure vessel A to be heated and cooled for adhesion or adhesive molding, an outer ventilation path is provided between the pressure vessel inner wall 2a and the wind tunnel wall 10, and an inner ventilation path 12 is provided inside the wind tunnel wall 10. And a plurality of gas suction ports 13 are arranged in series at an upper portion of the wind tunnel wall 10 at regular intervals,
A plurality of gas outlets 14 are provided in the lower portion so as to correspond to the gas inlets, and fans 15 are disposed in the plurality of gas inlets 13 and the external ventilation passage is provided for each adjacent fan of the container 2. The external ventilation passages 11c and 11d are formed by alternately partitioning one side into a narrow outlet side 17a in the circumferential direction and the other side into a wide outlet side 17b by a partition member 17 to an appropriate position to form the external ventilation passages 11c and 11d. The gas blown by the air is separated from each other in the opposite ventilation paths 11c.
And 11d branch and flow, and outside ventilation passage 11c and outside ventilation passage 1
At each end of 1d, the flow of gas blown by the adjoining fan 15 interacts with each other, and at the gas outlet 14 the outside ventilation passage 1
The alternating gas of 1c and the alternating gas of the external ventilation passage 11d further exchange and flow into the internal ventilation passage 12, and are appropriately divided into a plurality of gas suction ports 13 and circulated.

[0010]

Embodiments of the present invention will be described below with reference to the accompanying drawings. Example 1 As shown in (a) of FIG. 1 and FIG. 3, an autoclave molding apparatus for carrying out the present invention arranges a material 1 to be adhered or adhesively molded on a carriage 4 and accommodates it in a container 2 and a door 3 , A pressure vessel A that can be hermetically sealed, a pressurizing means B that supplies high-pressure gas to the pressure vessel A, and a gas blown by each fan provided at a plurality of gas suction ports are separated from each other. The gas circulation means C provided so as to flow through the outer ventilation passages 11a and 11b in the direction and exchange at the gas outlet 14 to flow into the inner ventilation passage 12, and be appropriately divided into a plurality of gas suction ports 13 for circulation. A plurality of heat exchangers 18 are provided in the outside ventilation passage 11.
And cooling means D for heating and cooling the circulating gas body
And a gas temperature control means E provided to control the temperature of the gas body circulating in the gas circulation means C.

Embodiment 2 The pressure vessel A, pressurizing means B, heating / cooling means D,
As shown in FIG. 2 and FIG. 3B, the gas temperature control means E and the air blown by the respective fans 15 arranged at the plurality of gas suction ports 13 are separated from each other and the external ventilation passages in opposite directions. 11 c and 11 d are branched and flow, and at the end of each of the outer ventilation passage 11 c and the outer ventilation passage 11 d, the flow of gas blown by the adjacent fan 15 is exchanged, and at the gas outlet 14 of the outer ventilation passage 11 c. Exchanged gas and external ventilation passage 1
The gas circulation means F is provided so that the alternating gas of 1d further exchanges and flows into the internal ventilation passage 12 and is appropriately divided into a plurality of gas suction ports 13 to circulate.

Next, details of each means will be described. Example 1 As shown in (a) of FIG. 1 and FIG. 3, the pressure vessel A is a vessel 2 in which a rail 5 for laying in and carrying in a material 1 to be bonded or adhesively molded is placed on a carriage 4; It is composed of a door 3 for opening and closing 2.

As shown in FIG. 1, the pressurizing means B supplies gas such as high-pressure nitrogen gas, high-pressure carbon dioxide gas, and high-pressure air from a high-pressure gas supply source 6 through an automatic valve 7 and an automatic valve 8. It is configured to be exhausted.

As shown in FIG. 1 and FIG. 3A, the gas circulation means C has an outer ventilation passage between the pressure vessel inner wall 2a and the wind tunnel wall 10 and an inner ventilation passage 12 inside the wind tunnel wall 10. To form
A plurality of gas suction ports 13 are provided in series in the upper part of the wind tunnel wall 10 at regular intervals, and a plurality of gas blow ports 14 are provided in the lower part in correspondence with the gas suction ports 13. Each of the fans 13 is provided with a fan 15, and the external ventilation passages are separated by adjoining fans by a partition member 16 in the longitudinal direction of the container 2 to form external ventilation passages 11a and 11b. . And each fan 1
As shown in (a) of FIG. 1 and FIG. 3, the gas blown by the air blower 5 is divided into external ventilation passages 11a in opposite directions.
And 11b to be exchanged at the gas outlet 14 to flow into the inner ventilation passage 12, pass through the inner ventilation passage, and pass through the plurality of gas inlets 13
It is configured to be appropriately diverted to circulate.
Here, the gases blown by the respective fans 15 are separated from each other by the external ventilation passages 11a and 1a in opposite directions.
Since it is heated or cooled with 1b and has an alternating current at the gas outlet 14, even if there is a temperature difference between adjacent separated gases, they are mixed and become a uniform temperature. In this embodiment, the fan 15 is rotatably supported by the motor 15a from the outside of the pressure vessel A through a seal. For example, the motor 15a is sealed with a small pressure vessel to cool the inside of the vessel. Alternatively, in the present embodiment, the gas flow is from the outer ventilation passage 11 to the gas outlet 14 to
Although it is circulated from the inner ventilation passage 12 to the gas suction port 13,
For example, by rotating the pressure vessel A by 90 degrees, the gas suction port 13
May be set to the lateral direction so that the gas suction port 13 serves as a gas outlet and the gas flows in the opposite direction, and the present invention is not limited to the present embodiment.

The heating / cooling means D is provided in the outside ventilation passages 11a and 11b as shown in FIG. 1 or as shown in FIG.
The heat exchanger 18 (heater 18a and cooler 18b) is provided in 11c and 11d to heat and cool the circulating gas body. When the heater 18a of the heat exchanger 18 is steam, the pressure vessel is opened via the automatic valve 19. The electric heater is provided so that it can be controlled, and in the case of an electric heater, although not shown, it is provided so that it can be controlled through a power regulator. Also, cooler 18b
Passes through the pressure vessel A via the automatic valve 20 and the heat exchanger 1
8 to supply cooling water to the heat exchanger 18
The lower part of the pressure vessel A is made to communicate with the lower part of the above so that the cooled water can be discharged through the automatic valve 21.
As another example of the heating / cooling means D, the heat medium is heated and cooled outside the pressure vessel A, and the heat medium is passed through the external ventilation passages 11a, 1a.
Heat exchanger 18 provided on 1b or on 11c and 11d
The gas may be heated and cooled via the above-mentioned method, and the present invention is not limited to the embodiments.

As shown in FIG. 1, the gas temperature control means E is provided with a temperature sensor 23 at an appropriate position of the gas circulation means C and detects the circulating gas body temperature by the temperature sensor 23 to detect the gas body temperature. Is compared with a preset temperature programmed by the setter 24 by the controller 25, and the difference is transmitted to the heating / cooling means D to control the heater (or cooler) and the gas circulating in the gas circulation means C is compared. The body temperature is controlled so that the temperature is suitable for the material 1. The program can set the pressure as required, and the pattern of the program also differs depending on the type, shape, size, etc. of the material, and is not limited to this embodiment.

Embodiment 2 The gas circulation means F is, as shown in FIGS. 2 and 3 (b),
An outer ventilation passage is formed between the pressure vessel inner wall 2a and the wind tunnel wall 10, and an inner ventilation passage 12 is formed inside the wind tunnel wall 10.
In the upper part of 0, a plurality of gas suction ports 13 are provided in series at regular intervals, and in the lower part, a plurality of gas blow ports 14 are provided corresponding to the gas suction ports, and the plurality of gas suction ports 13 are respectively provided. An appropriate position is provided by the partition member 17 so that the fan 15 is arranged and the outside ventilation passage is arranged in the circumferential direction of the container 2 for each adjacent fan and one is a narrow outlet portion 17a and one is a narrow outlet portion 17b. The outer ventilation passages 11c and 11d are formed by alternately partitioning up to. And
As shown in FIG. 2, the gas blown by each fan 15 is divided into outer ventilation passages 1 in opposite directions.
1 c and 11 d branch off and flow, and at the end of each of the outer ventilation passage 11 c and the outer ventilation passage 11 d, alternating with the flow of gas blown by the adjacent fan 15, and at the gas outlet 14 of the outer ventilation passage 11 c. The exchanged gas and the exchanged gas in the outer ventilation passage 11d further exchange to flow into the inner ventilation passage 12, pass through the inner ventilation passage, and are appropriately divided into a plurality of gas suction ports 13 to circulate. It is configured in. Here, the gas heated or cooled in the outer ventilation passage 11c and the outer ventilation passage 11d is exchanged with the flow of gas blown by the fan 15 adjacent to each other at the end of each of the outer ventilation passage 11c and the outer ventilation passage 11d. In such a case, as shown in FIG. 2, the gas flowing out of the narrow outlet portion 17a and the gas flowing out of the adjacent wide outlet portion 17b are exchanged with each other, so that the temperature of the gas blown by each fan is compared. , Even if there is a temperature difference, it is uniformed by alternating current. Furthermore, this uniformed external ventilation passage 11
Since the gas of c and the gas of the outer ventilation passage 11d are further exchanged at the gas outlet 14, the temperature of the gas is made more uniform and there is no temperature difference. And this gas circulation can freely come and go from the inlet side of the pressure vessel A to the inner side,
It is possible to circulate at almost the same temperature in each position inside the pressure vessel A.

Next, the operation will be described. Example 1 First, a material 1 to be bonded or adhesively molded, in this example,
As shown in FIG. 1 and FIG. 3A, a plurality of laminated glasses are housed in a pressure vessel A, arranged in a vertical position, and sealed by a door 3. Next, according to the program shown in FIG. 4, the heater 17a of the pressurizing means B and the heating / cooling means D is operated to pressurize and heat, and the gas circulating means C is operated. Then, the gas blown by the respective fans 15 passes through the divided outer ventilation passages 11 a and 11 b in opposite directions and is exchanged with each other at the gas outlet 14 to flow into the inner ventilation passage 12 to pass through the gap of the material 1. As described above, the material 1 is heated and lifted, appropriately divided into the plurality of gas suction ports 13, and then blown again by the fan to circulate the gas. Then, as shown in FIG.
The temperature of the gas detected by the temperature sensor 23 installed in the gas circulating means C is compared with the preset temperature programmed by the setter 24 by the controller 25, and the difference is transmitted to the heating / cooling means D. Then, the heater 18a is controlled to control the temperature of the gas circulating in the gas circulating means C.

Next, in the cooling stage, the exhaust valve 8 of the pressurizing means B is operated to reduce the pressure according to the program shown in FIG. 4, and the cooler 18b of the heating / cooling means D is operated to control the temperature of the gas body. Controllably cool material 1. Then, the material is cooled to an appropriate temperature, the pressure is returned to the atmospheric pressure, the door 3 is opened, and the material 1 is unloaded to complete one step.

Example 2 First, the material 1 to be bonded or adhesively molded, in this example,
As shown in FIGS. 2 and 3B, a plurality of laminated glasses are housed in the pressure vessel A and sealed by the door 3. Next, according to the program shown in FIG. 4, the heaters 18a of the pressurizing means B and the heating / cooling means D are operated to pressurize and heat, and the gas circulating means F is operated. Then, the gas blown by each fan 15 is branched and flows into the separated outer ventilation passages 11c and 11d in opposite directions, as shown in (b) of FIG. 2 and FIG.
And the flow of gas blown by the adjoining fan 15 at each end of the outer ventilation passage 11d, and the gas blown out from the outer ventilation passage 11c was exchanged with the gas blown by the adjacent fan 15. The gas exchanges more and flows into the inner ventilation passage 12,
When the material 1 is touched, the material 1 is heated and lifted, appropriately branched to the plurality of gas suction ports 13, and then blown again by the fan 15 to circulate the gas. Then, as shown in Example 1,
The temperature of the gas detected by the temperature sensor 23 is set in advance by the setter 24 and the controller 25.
Then, the difference is transmitted to the heating / cooling means D to control the heater 18a and control the temperature of the gas body circulating in the gas circulating means F.

Next, in the cooling step, the exhaust valve 8 of the pressurizing means B is operated to reduce the pressure according to the program shown in FIG. 4, and the cooler 18b of the heating / cooling means D is operated to control the temperature of the gas body. Controllably cool material 1. Then, the material is cooled to an appropriate temperature, the pressure is returned to the atmospheric pressure, the door 3 is opened, and the material 1 is unloaded to complete one step.

[0022]

According to the present invention, the gas blown by the respective fans 15 arranged in the gas suction port 13 passes through the divided external ventilation passages 11a and 11b in the opposite directions at the gas outlet 14. Since they flow to the inner ventilation passage 12 by alternating current and are diverted appropriately to the plurality of gas suction ports 13 to circulate, the separated outer ventilation passages 1 in opposite directions are provided.
Since the gas passing through 1a and 11b exchanges each other,
Even if there is a temperature difference between adjacent separated gases, they are mixed and become a uniform temperature, and as time passes, the gases sequentially move in the direction of the adjacent fan, and the gas temperature of the entire pressure vessel A changes. Since it is completely homogenized, the gas body temperature can touch each material 1 arranged at each position of the pressure vessel A under the same condition, and conventionally, heating of the material 1 arranged at the inlet side or the back side of the pressure vessel A is possible. , Adhesiveness due to cooling temperature difference,
The adverse effects of adhesive moldability are completely eliminated, and uniform and high-quality products can be obtained. Further, the gas blown by the respective fans 15 arranged in the gas suction port 13 branches into the external ventilation passages 11c and 11d, which are separated from each other and flow in the opposite directions, and the gas flows in the external ventilation passages 11c and 11d. At each end, the flow of gas blown by the adjacent fan is exchanged with each other, and at the gas outlet 14, the exchanged gas in the external ventilation passage 11c and the exchanged gas in the external ventilation passage 11d are further exchanged. Since the material flows to the inner ventilation passage 12 and touches the material 1 to be heated, the material 1 is appropriately divided into a plurality of gas suction ports 13 and circulated.
Since the gas exchanged in the outer ventilation passage 11c and the gas exchanged in the outer ventilation passage 11d at the gas outlet 14 can further exchange with each other and flow into the inner ventilation passage 12, for example, the adjacent separated gas. Even if there is a temperature difference between the separated gas on the inlet side or the inner side of the pressure vessel A, the temperature is made uniform more quickly by further mixing. Moreover, as time passes, the gas sequentially moves toward the adjacent fan to completely equalize the gas temperature of the entire pressure vessel A. Therefore, the temperature of the completely homogenized gas is equal to that of the pressure vessel A. Each material 1 arranged at each position can be touched under the same conditions, and conventionally, the material 1 arranged on the inlet side or the back side of the pressure vessel A is adversely affected by the temperature difference between heating and cooling. The variation in the adhesiveness or the adhesive moldability of the product caused by the temperature difference of the same material 1 due to the inability to control the temperature of the gas in each gas circulation zone Ca is eliminated, and a uniform and high-quality product can be obtained.

[Brief description of drawings]

FIG. 1 shows a partially cutaway schematic top view of an autoclave apparatus for carrying out the present invention and a block diagram of a gas temperature control means.

FIG. 2 is a partially cutaway schematic top view of another embodiment of the autoclave apparatus for carrying out the present invention.

FIG. 3 is a partially cutaway schematic front view of an autoclave apparatus for carrying out the present invention, in which (a) shows a first embodiment and (b) shows a second embodiment.

FIG. 4 shows an example of an autoclave bonding and adhesive molding program embodying the present invention.

FIG. 5 is a schematic side view in which an example of a conventional autoclave device is partially broken.

[Explanation of symbols]

 A pressure vessel B pressurizing means C gas circulation means Ca gas circulation zone D heating / cooling means E gas temperature control means F gas circulation means 1 material 2 container 2a container inner wall 3 door 4 truck 5 rail 6 high pressure gas supply source 7 automatic valve 8 Automatic valve 10 Wind tunnel wall 11 Outer air passage 11a Outer air passage 11b Outer air passage 11c Outer air passage 11d Outer air passage 12 Inner air passage 13 Gas suction port 14 Gas outlet 15 Fan 15a Motor 16 Partition member 17 Partition member 18 Heat exchange 18a Heater 18b Cooler 19 Automatic valve 20 Automatic valve 21 Automatic valve 23 Temperature sensor 24 Setting device 25 Controller

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location B29K 105: 06

Claims (2)

[Claims] 1. In an autoclave in which a material 1 is pressurized and heated and cooled in a pressure vessel A to be bonded or adhesively molded, an outer ventilation passage is provided between an inner wall 2a of the pressure vessel and a wind tunnel wall 10, and an inside of the wind tunnel wall 10 is provided. An inner ventilation passage 12 is formed in the wind tunnel wall 1
In the upper part of 0, a plurality of gas suction ports 13 are provided in series at regular intervals, and in the lower part, a plurality of gas blow ports 14 are provided corresponding to the gas suction ports, and the plurality of gas suction ports 13 are respectively provided. A fan 15 is provided, and the external ventilation passages are separated from each other by adjacent partition members 16 in the lengthwise direction of the container 2 to form external ventilation passages 11a and 11b, which are blown by the respective fans 15. The gas flowing through the air passages 11a and 11b, which are separated from each other and in opposite directions, exchanges with each other at the gas outlet 14 to flow into the inner air passage 12, and is appropriately divided into a plurality of gas inlets 13 for circulation. A method of circulating gas in an autoclave, characterized in that 2. In an autoclave in which a material 1 is heated and cooled under pressure to be bonded or adhesively molded in a pressure vessel A, an outer ventilation passage is provided between an inner wall 2a of the pressure vessel and a wind tunnel wall 10, and an inside of the wind tunnel wall 10 is provided. An inner ventilation passage 12 is formed in the wind tunnel wall 1
In the upper part of 0, a plurality of gas suction ports 13 are provided in series at regular intervals, and in the lower part, a plurality of gas blow ports 14 are provided corresponding to the gas suction ports, and the plurality of gas suction ports 13 are respectively provided. A fan 15 is provided and the partition member 17 is provided so that the outside air passage is arranged in a circumferential direction of the container 2 for each adjacent fan and one is a narrow outlet portion 17a and the other is a wide outlet portion 17b. Alternating airway 11
c and 11d are formed, and the gas blown by each fan 15 is branched and flows into the external ventilation passages 11c and 11d which are separated from each other in opposite directions, and the gas is blown in each of the external ventilation passages 11c and 11d. In the final section, the flow of gas blown by the adjacent fan 15 is exchanged, and at the gas outlet 14, the exchanged gas in the external ventilation passage 11c and the exchanged gas in the external ventilation passage 11d are further exchanged to the inside. A gas circulation method for an autoclave, characterized in that the gas flows into the ventilation passage 12 and is appropriately divided into a plurality of gas suction ports 13 for circulation.