Underbody structure of vehicle

An underbody structure of a vehicle, the underbody structure comprising:

• a cross member provided on an upper surface of a floor panel, the cross member extending in a vehicle width direction of the vehicle;
• a side sill coupled to an outer end of the floor panel in the vehicle width direction, the side sill extending in a front-rear direction of the vehicle;
• and
• a gusset,
• wherein the cross member and the side sill are separated in the vehicle width direction,
• wherein the gusset is interposed between the cross member and the side sill, and
• wherein the gusset includes:
• a front side wall and a rear side wall in pairs, each of the front side wall and the rear side wall comprising a lower end coupled to an outer end of the cross member in the vehicle width direction;
• an upper wall that coupled to an upper end of each of the front side wall and an upper end of the rear side wall;
• a protrusion provided at an outer end of the upper wall in the vehicle width direction, the protrusion protruding outward in the vehicle width direction from the upper wall;
• and
• a front flange and a rear flange in pairs, each of the front flange and the rear flange extending from a predetermined position in a vertical direction of an outer end of a corresponding one of the front side wall and the rear side wall in the vehicle width direction to a predetermined position in the vehicle width direction of a lower end of the corresponding one of the front side wall and the rear side walls, each of the front flange and the rear flange extending outward in the front-rear direction from the corresponding one of the front side wall and the rear side wall, each of the front flange and the rear flange being coupled to (i) a side part of the side sill and (ii) the outer end of the cross member in the vehicle width direction,
• wherein the protrusion of the gusset includes:
• an upward extending part that extends upward from an outer end of the upper wall in the vehicle width direction and that is inclined outward in the vehicle width direction;
• and
• a joining part extending outward in the vehicle width direction from an upper end of the upward extending part and that is joined to an upper wall of the side sill, and a U shaped reinforcement within the cross member and below the gusset.