Gas injection device and balloon

A gas injection apparatus for injecting gas into a balloon body from a balloon valve connected to a gas injection pipe of the balloon body, the gas injection apparatus comprising:

• a nozzle configured to be inserted into the balloon valve and to inject gas into the balloon body;
• a valve mechanism configured to open and close a gas flow path to the nozzle;
• a drive mechanism configured to move the nozzle forward and backward;
• a balloon case including a first case piece and a second case piece connected to be bendable, and including an unfold opening formed by opposing slots provided in the first case piece and the second case piece in a closed state;
• a balloon case placing section having a flat bottom surface on which the balloon case housing the balloon body and including the balloon valve is placeable, the balloon case placing section being configured to position the balloon valve such that an open end of the balloon valve faces a forward movement direction of the nozzle;
• a projection part provided on the flat bottom surface of the balloon case placing section and configured to engage with a finger insertion part formed in the balloon case to fix a position of the balloon case on the balloon case placing section;
• wedge-shaped bodies configured to move in conjunction with the nozzle by the drive mechanism and to be inserted into the unfold opening to open the balloon case;
• and
• a control unit configured to control the drive mechanism and the valve mechanism, wherein
• the control unit is configured to:
• move the nozzle forward in response to a start instruction,
• insert the nozzle into the balloon valve to bring the nozzle and the balloon valve into tight contact without clearance, and
• inject gas into the balloon body while maintaining the tight contact.