Air tightness detection device

The utility model discloses an air tightness detection device, which is used for detecting the air tightness of a battery monomer at least comprising a groove body and a groove cover, and comprises an air nozzle, a body used for being plugged into an inlet in the groove cover, and an air pipe fixed on the body and used for communicating the inside and the outside of the battery monomer, at least the upper end face of the body is a plane. The annular shell is used for sleeving the periphery of the matching part of the tank body and the tank cover; the cross beam is used for carrying the upper end face of the body, the two ends of the cross beam are fixedly connected with the annular shell, and a through hole for an air supply pipe to penetrate through is formed in the cross beam. By virtue of the gravity of the annular shell, the body of the air tap is pressed downwards to be in close contact with the groove cover of the battery monomer; and meanwhile, deformation of the tank body caused by gas entering the ta