Side airbag device

A side airbag device comprising:

• an inflator mounted to a seat frame;
• a cushion covering the inflator and configured to be deployed by gas discharged from the inflator to protect a side portion of occupant passenger;
• and
• a tether mounted to the inflator and configured to enclose the cushion and reduce collision energy applied to the passenger,
• wherein:
• the cushion comprises:
• a cushion deployment part mounted to the inflator and configured to be deployed by gas discharged from the inflator;
• a cushion passing part formed in the cushion deployment part so that the tether passes through the cushion passing part;
• and
• a cushion penetration part formed in an upper end of the cushion deployment part so that the tether penetrates the cushion penetration part;
• the tether comprises:
• a first tether fixed to the inflator, disposed on an inner side surface of the cushion deployment part, and reaching the cushion passing part;
• a second tether extending from the first tether, reaching the cushion penetration part via the cushion passing part, and disposed on an outer side surface of the cushion deployment part;
• and
• a third tether extending from the second tether, disposed on the inner side surface of the cushion deployment part, and fixed to the inflator and configured to support the passenger;
• the third tether has a width that is different from a width of the first tether and a width of the second tether;
• and
• a medial portion of the tether has a width greater than a width of each end of the tether.