Suction discharge unit and suction discharge device

A suction discharge unit disposed between a subject and a suction source, comprising:

• a first connection hole communicating with the subject;
• a second connection hole communicating with the suction source;
• a storage chamber storing a first liquid flowing into the storage chamber from the first connection hole;
• a water sealing chamber including a first chamber, a second chamber, a first partition wall, a second chamber, a water sealing part and a second partition wall, wherein the first chamber communicates with the storage chamber, the first partition wall prevents the first liquid from passing into the first chamber, and the second chamber is isolated from the first chamber by the water sealing part and the second partition wall and is connected to the suction source via the second connection hole;
• and
• a negative pressure control unit controlling a pressure of the first chamber by causing a gas to flow from the second chamber to the first chamber based on a pressure of the second chamber and the pressure of the first chamber;
• wherein the negative pressure control unit includes a liquid retaining part allowing a second liquid to be retained and disposed such that the pressure of the second chamber acts on the second liquid, and
• a control hole for controlling an inflow of the gas based on a surface tension of the second liquid.