Automotive suspension control system with road-condition-dependent damping characteristics

A road surface sensing system for an automobile having sprung mass and unsprung mass and a suspension control system with damping characteristics that adapt automatically to changes in road surface conditions comprising:

• a sensor producing a sensor signal representative of the magnitude of relative displacement between a vehicle body and a wheel axle, said signal having a first frequency component and a second frequency component;
• means for comparing the amplitude of said first frequency component of the sensor signal with a predetermined reference value, said comparing means producing a first or second signal of a predetermined level indicative of a rough road surface or a smooth road surface, respectively;
• a means for comparing the amplitude of said second frequency component of said sensor signal with a predetermined second reference level and outputting a third signal when said amplitude exceeds said second reference level.

A road surface sensing system for an automobile having sprung mass and unsprung mass and a suspension control system with damping characteristics that adapt automatically to changes in road surface conditions comprising:

• a sensor producing a sensor signal representative of the magnitude of relative displacement between a vehicle body and a wheel axle, said signal having a first frequency component and a second frequency component;
• means for comparing the amplitude of said first frequency component of the sensor signal with a predetermined reference value, said comparing means producing a first or second signal of a predetermined level indicative of a rough road surface or a smooth road surface, respectively, said comparing means comprising a first comparator for comparing the magnitude of vibration of said sprung mass with a first reference level and producing a first comparator signal when the magnitude of vibration exceeds a first reference level, and a second comparator for comparing the magnitude of vibration of said unsprung mass with a second reference level and producing a second comparator signal when the magnitude of the vibration caused by said unsprung mass exceeds a second reference level, the combination of said first and second comparator signals representing road surface conditions.

A road sensing system for an automobile having sprung and unsprung mass and a suspension control system with damping characteristics that adapt automatically to changes in road surface conditions, said road surface sensing system comprising:

• a sensor producing a sensor signal having specific frequency range components with amplitudes representative of the magnitude of vibration of the sprung mass of the automobile;
• and
• means sensitive to a specific frequency range of said sensor signal for comparing the amplitude of said specific frequency range with a reference value, said comparing means comprising a first comparator for comparing the amplitude of the sensor signal component in said specific frequency range with a first reference level, a second comparator for comparing the amplitude of sensor signal components in a second frequency range, and outputting a second comparator signal when said amplitude exceeds said second reference level.