Patent ID: 8321087

Claim:
A damping force control apparatus, applied to a plurality of suspension apparatuses, each having a spring and a damper and interposed between a sprung member and an unsprung member to support the sprung member, for controlling a damping force characteristic of the damper comprising: damping force characteristic changing means for changing said damping force characteristic of each of the dampers; sprung-member-unsprung-member-relative-speed obtaining means for obtaining a sprung-member-unsprung-member-relative-speeds, each representing a vibration speed of each of said suspension apparatuses in a vertical direction, said sprung-member-unsprung-member-relative-speed being defined as a positive relative speed when a distance between said sprung member and said unsprung member is decreasing in a case where a sprung member speed which is a speed of said sprung member moving in an upper direction is defined to be positive, and said sprung-member-unsprung-member-relative-speed being defined as a positive relative speed when said distance between said sprung member and said unsprung member is increasing in a case where a speed of said sprung member moving in a lower direction is defined to be positive; sum of sprung member speeds obtaining means for obtaining a sum of sprung member speeds which is a summation of each speed of said sprung member in the vertical direction at a position at which said sprung member is supported by each of said plurality of suspension apparatuses; positive-negative determining means for determining whether a product of said sum of sprung member speeds and each of said sprung-member-unsprung-member-relative-speeds is positive or negative; damping force characteristic control means for controlling an operation of said damping force characteristic changing means in such a manner that said damping force characteristic of each of said dampers is changed according to a vibration state of said sprung member when it is determined that each of said products is positive by said positive-negative determining means; and operation prohibiting means for prohibiting an operation of said damping force characteristic changing means when it is determined that each of said products is negative by said positive-negative determining means.