Adjustable constant pressure device

An adjustable constant pressure device, comprising:

• a connector;
• a sealing shaft;
• a constant pressure assembly;
• and
• a mobile mechanism;
• wherein,
• the connector comprises an axially extended assembly channel;
• the sealing shaft and the constant pressure assembly are disposed in the assembly channel;
• the sealing shaft comprises a sealing channel and an air outlet communicating with the sealing channel;
• the constant pressure assembly comprises one end axially oriented to the air outlet, and the end is sealed;
• the constant pressure assembly comprises a constant pressure channel;
• when an air pressure in the constant pressure channel is higher than that in the sealing channel, the constant pressure assembly moves along the assembly channel to seal the air outlet;
• when the air pressure in the constant pressure channel is lower than that in the sealing channel, the constant pressure assembly moves along the assembly channel to open the air outlet;
• and
• the mobile mechanism is connected to the connector and the sealing shaft, and is configured to move to drive the sealing shaft to move along the assembly channel.