Culture apparatus

1. A culture apparatus comprising:

an inner box configured to form a culture chamber in which culture is cultured;

an outer box configured to cover the inner box;

a fan disposed in the inner box and configured to circulate gas inside the culture chamber through an air passage provided in the inner box within the culture chamber;

a first through hole configured to penetrate a wall configuring a part of the air passage in the inner box;

a second through hole configured to penetrate the wall and disposed at a position at which a flow velocity of the gas circulated through the air passage by the fan is lower than a flow velocity of the gas around the first through hole;

a connecting pipe configured to connect the first through hole and the second through hole outside of the inner box in a manner allowing fluid communication of the gas in the culture chamber; and

a sensor configured to detect a concentration of the gas flowing in the culture chamber,

wherein the first and second through holes are formed on a same wall among the walls configuring the inner box in a manner such that the first through hole is provided on an upstream side of a direction of flow of the gas in the air passage within the culture chamber and the second through hole is provided on a downstream side of the direction of flow, and

wherein the culture apparatus is configured such that the gas in the connecting pipe flows from the second through hole to the first through hole.

2. The culture apparatus according to claim 1 , further comprising a wall plate configured to oppose a face of the wall to which the first and second through holes are formed, and form the air passage of the gas circulated by the fan.

3. The culture apparatus according to claim 2 , further comprising an injection port disposed in the air passage at an upstream position in a flowing direction of the gas from the first through hole and configured to inject the gas provided from an outside of the outer box, in a direction different from the flowing direction of the gas with regard to the first through hole.

4. The culture apparatus according to claim 1 , further comprising a heater configured to heat a part of the connecting pipe projecting to an outside of the outer box, to a temperature higher than an inside of the culture chamber.

5. The culture apparatus according to claim 1 , wherein the gas in the connecting pipe flows from the second through hole to the first through hole without using a suction device.

6. The culture apparatus according to claim 1 , wherein a flow of the gas in the connecting pipe is generated by only a difference in atmospheric pressure occurring from a difference of flow velocity between a vicinity of the first through hole and a vicinity of the second through hole.

7. A culture apparatus comprising:

an inner box configured to form a culture chamber in which culture is cultured;

an outer box configured to cover the inner box;

a fan disposed in the inner box and configured to circulate gas inside the culture chamber through an air passage provided in the inner box within the culture chamber;

a first through hole configured to penetrate a wall configuring a part of the air passage in the inner box;

a second through hole configured to penetrate the wall;

a connecting pipe configured to connect the first through hole and the second through hole outside of the inner box in a manner allowing fluid communication of the gas in the culture chamber; and

a sensor configured to detect a concentration of the gas flowing in the culture chamber,

wherein the first and second through holes are formed on a same wall among the walls configuring the inner box in a manner such that the first through hole is provided on an upstream side of a direction of flow of the gas in the air passage within the culture chamber and the second through hole is provided on a downstream side of the direction of flow, and

wherein the connecting pipe is not connected to a suction device.