System for controlling damping force characteristic of shock absorber of vehicle

A system for controlling damping forces for respective shock absorbers of a vehicle, comprising:

• a) a plurality of shock absorbers, each shock absorber being interposed between a sprung mass and unsprung mass of the vehicle and located adjacent to a corresponding one of a front left tire wheel, front right tire wheel, rear left tire wheel, and rear right tire wheel of the vehicle,
• b) damping force characteristic changing means for changing a damping force characteristic of each shock absorber at either or both of stroke directions with respect to a piston of each shock absorber in response to an input control signal;
• c) front tire wheel side sprung mass vertical velocity determining means for determining a front tire wheel side sprung mass vertical velocity;
• d) front tire wheel side relative velocity determining means for determining a relative velocity between the sprung mass and unsprung mass of the vehicle at the front tire wheels side;
• e) means for deriving a front tire wheel side road surface input velocity from the front tire wheel side sprung mass vertical velocity and from the front tire wheel side relative velocity between the sprung mass and unsprung mass;
• f) rear tire wheel side sprung mass relative velocity determining means for determining a relative velocity between the sprung mass and unsprung mass at the rear tire wheels side;
• g) means for determining a rear tire wheel side sprung mass vertical velocity based on the rear tire wheel side relative velocity between the sprung mass and unsprung mass;
• and
• h) damping force characteristic controlling means for controlling the damping force characteristics of the shock absorbers located at the front tire wheels side on the basis of a first control signal determined on the basis of the front tire wheel side sprung mass vertical velocity via damping force characteristic changing means and for controlling the damping force characteristics of the shock absorbers located at the rear tire wheels side on the basis of a second control signal via said damping force characteristic changing means, the second control signal at the rear tire wheels side being determined on the basis of said front tire wheel side road surface input velocity and on the basis of said rear tire wheel side sprung mass vertical velocity.