Patent ID: 7243934

Claim:
A multi-link rear suspension system for a vehicle, comprising: a knuckle disposed within an internal space of a rear wheel; a rear subframe positioned along a width direction of the vehicle, said rear subframe increasing stiffness of a lower portion of a vehicle body by being coupled to the vehicle body; an upper arm with an end disposed in said internal space of said rear wheel for being coupled to an upper end of said knuckle, an opposite end of said upper arm being coupled to said rear subframe; a lower arm placed underneath said upper arm, one end of said lower arm being positioned in said internal space of said rear wheel to couple with a lower end of said knuckle while an opposite end couples to said rear subframe; an assist arm located toward a front of the vehicle body in relation to said rear subframe, one end of said assist arm being coupled to said knuckle and an opposite end being coupled to said rear subframe; a trailing arm disposed underneath said assist arm along an anteroposterior direction of the vehicle body, one end of said trailing arm being coupled to said knuckle and an opposite end thereof being coupled to a vehicle body; a coil spring fixed at a lower end thereof by being inserted into a fixing groove formed on said lower arm, an upper end of said coil spring being coupled to a vehicle body; and a shock absorber slopedly disposed at a predetermined offset angle θ1 from a central axis that passes through a center of said rear wheel in a vertical direction in relation to a roadway, a lower end of said shock absorber passing through a space between said lower arm and said assist arm for being coupled to said knuckle, and an upper end of said shock absorber being coupled to a vehicle body; wherein assist arm mounting bushings equipped at both ends of said assist arm and coupled to said knuckle and said rear subframe, respectively, have a lower elastic coefficient than that of lower arm mounting bushings equipped at both ends of said lower arm and coupled to said knuckle and said rear subframe, respectively; wherein said assist arm is constituted by: two bushing pipes inserted into said assist arm mounting bushings; and a connecting rod connecting said two bushing pipes, wherein said connecting rod is constituted by an assembly of an inner rod and an outer rod that are engaged with each other for being changeable in length against external force; an elastic member is mounted between one of said bushing pipes at said outer rod and one end of said inner rod; a snap ring is installed at an inner surface of said outer rod to prevent separation of said inner rod; and a blocking sill is formed at one end of said inner rod to be blocked by said snap ring.