Coupled torsion beam axle type of suspension system

A coupled torsion beam axle suspension system comprising:

• a trailing arm connected to each end of a torsion beam;
• a vehicle body fastener mounted at a front end of each trailing arm for mounting a vehicle body thereto;
• and
• a spindle bracket provided at a rear outer side of the trailing arm,
• wherein each vehicle body fastener includes:
• a trailing arm bush formed integrally with the trailing arm at the front end of the trailing arm;
• a bush link installed in front of the trailing arm bush and fastened to the trailing arm bush in a vehicle width direction;
• a lower mounting bush formed inside the bush link in a vehicle height direction at a front outer side of the trailing arm bush and fastened to a lower side of the vehicle body in the vehicle height direction;
• an upper mounting bush mounted at a rear side of the lower mounting bush to move the upper mounting bush up and down between the bush link and the vehicle body by a cylinder unit disposed between the bush link and the vehicle body;
• and
• a stay having one end fastened to one side of a lower surface of a side member of the vehicle body in the vehicle height direction together with the lower mounting bush from a lower side of the lower mounting bush by a bush bolt and another end mounted to the vehicle body by a fastener, and
• wherein an extension line, which passes a center of the lower mounting bush and a center of the trailing arm bush, forms an acute angle with a vehicle body length direction center line which passes the center of the trailing arm bush, and
• an instantaneous center of rotation, which is a crossing point of the left and the right extension line, is set to be behind a center of wheels.