1. Field of the Invention
The present invention generally relates to strut suspensions and more particularly, to a strut suspension having a strut whose upper end is supported by an automobile body and whose lower end is supported by a wheel side member, an upper side spring seat, a lower side spring seat fixed to the strut, and a coil spring arranged between the upper side spring seat and the lower side spring seat so as to surround the strut.
2. Description of the Related Art
A structure where a coil center axis (axial line) of a coil spring and a kingpin axis are twisted is known, compared to a normal strut suspension structure where the coil center axis of the coil spring and the kingpin shaft cross each other. See Japan Laid-Open Patent Application Publication No. 11-48728, for example. In such a suspension structure, for example, it is possible to improve responsiveness, stability or alignment of an automobile by creating a twisting relation whereby a moment in a toe-in direction is generated around the kingpin shaft.
However in the above-mentioned strut suspension, a moment is generated around the kingpin shaft even in a vehicle standard state, namely a vehicle stopping state wherein a rudder angle provides a neutral rubber position. Hence, if there is a difference of the moments between right and left sides, a bad influence may be made on a moving vehicle. In other words, if a difference of the twisting relation is generated between the right and left sides due to the influence of dispersion, for example, then different moments are always generated around left and right kingpin shafts so that a vehicle deflection (vehicle change in direction) may be generated. Hence, the stability or alignment of the automobile may be degraded.