1. Field of the Invention
This invention relates to a suspension system for use with automobiles and other vehicles.
2. Description of the Prior Art
Various types of suspension systems incorporating shock absorbers have been developed to absorb the shocks vehicles encounter on the road.
The drawback with these conventional suspension systems is to sacrifice either riding comfort or steering stability.
To provide a comfortable ride, suspensions must be elastic (or "soft"). But soft suspensions inevitably lower handling stability.
If a vehicle with a soft suspension runs over an upward step (including a bulge) or a downward step (including a depression) on the road, the car body may pitch or bounce uncomfortably, and further the riding comfort is lowered and some parts of the vehicle might be damaged with the suspension either over-compressed or over-stretched.
Among the prior art, a Japanese Patent Application whose early publication number is 53-26021, discloses a suspension system wherein the spring constant of a suspension is adapted to be increased when the stroke amount (=the moving distance of a wheel with respect to a car body) exceeds a preset value. This suspension system can prevent the car-height from lowering through hard buffering action in the case of the spring constant increased. On the other hand, however, this suspension system aggravates the upward displacement of the car-height. And further it has such a drawback that the car body continues to bounce uncomfortably for a rather long time after the car passed a step (e.g., a depression or bulge) on the road.