Ventilation switching structure of negative pressure regulator

A ventilation switching structure of a negative pressure regulator, used for connecting with a negative pressure instrument, the ventilation switching structure comprising:

• a valve, comprising a receiving room, a main tube and a pair of branch tubes, the main tube being used for connecting with the negative pressure instrument and connected to the receiving room, and the pair of branch tubes being correspondingly located on two sides of the main tube;
• a switching cylinder, rotatably disposed in the receiving room, comprising a main channel, a plurality of lateral channels and a blocking wall, the lateral channels being communicated with the main channel, and the lateral channels being disposed at a side of the blocking wall and at intervals;
• and
• a knob, connected on the switching cylinder, the knob being capable of rotating the switching cylinder to make the blocking wall optionally block one of the branch tubes.