Abstract: A suspension control system capable of controlling a suspension of an automotive vehicle in such a manner as to improve the riding comfort and maneuverability of the vehicle without the need for many sensors is disclosed, in which a speed difference signal obtained by subtracting an estimated vehicle speed from a wheel speed is filtered with band-pass filters which pass sprung resonance frequency components and unsprung resonance frequency components, respectively. After amplification, the filtered speed difference are compared with a reference value so that a damping force of a shock absorber is set in accordance with a road surface condition. Since the damping force of the shock absorber is shifter by using only information based on the wheel speed detected by a wheel speed sensor, a total number of sensor to be mounted on the vehicle for controlling the suspension can be considerably reduced. The suspension control system is simple in construction and can be manufactured at a relatively low cost.

Abstract: A suspension control system for controlling a suspension having a shock absorber provided for each wheel of a vehicle includes a damping force change rate detector which detects a damping force change rate indicating a rate of change of a damping force of the shock absorber, and a damping force controller which alters the setting of the damping force on the basis of a relationship between the damping force change rate and an adjustment reference value. The system also includes a road surface condition detector which detects a condition of a road surface on which the vehicle is running on the basis of a change of the damping force of the shock absorber. Further, the system includes a damping force adjustment correcting unit which corrects the adjustment reference value by learning the adjustment reference value on the basis of a parameter related to the damping force of the shock absorber which reflects the condition of the road surface.

Abstract: A suspension control system for controlling a suspension having a shock absorber provided for a wheel of a vehicle includes a damping force detector which generates a damping force detection signal which indicates a change of a damping force of the shock absorber based on a condition of a road surface on which the vehicle is running. The system also includes a sprung resonance component extraction unit which extracts a sprung resonance component signal from the damping force detection signal. The sprung resonance component signal includes components having frequencies around a sprung resonance frequency of the shock absorber. Further, the system includes a determining part which determines whether or not the sprung resonance component signal exceeds a first level range provided for detecting a sign of the occurrence of a long-term vehicle vibration and which outputs a determination result.

Abstract: The expanding/contracting accelerations of shock absorbers on a motor vehicle are detected and compared with preset accelerations, respectively, by an electronic controller, which individually varies the damping forces of the shock absorbers as a result of the comparison. The electronic controller corrects the preset accelerations so that the damping forces of the shock absorbers will be switched over at a uniform frequency or the damping forces of the front left and rear left shock absorbers and the damping forces of the front right and rear right shock absorbers will be switched over at a constant frequency.

Abstract: A suspension control system for controlling a suspension having a shock absorber provided for a wheel of a vehicle includes a damping force change rate detector which detects a damping force change rate indicating a rate of change of a damping force of the shock absorber, and a damping force controller which alters the setting of the damping force on the basis of the relationship between the damping force change rate and an adjustment reference value. The system also includes a road surface condition detector which detects, for every first period, the condition of a road surface on which the vehicle is running on the basis of a change of the damping force of the shock absorber, and a damping force adjustment correcting unit which corrects the adjustment reference value by learning, for every second period, the adjustment reference value on the basis of a parameter related to the damping force of the shock absorber which reflects the condition of the road surface.

Abstract: A variable-damping-force shock absorber includes a piezoelectric actuator for producing a displacement, a hydraulic pressure chamber filled with a working oil and having a volume variable in response to the displacement produced by said piezoelectric actuator, and a plunger slidably disposed in a sleeve and reciprocally movable in response to a change in the volume of said hydraulic pressure chamber. The sleeve and said plunger define therebetween a gap communicating with said hydraulic pressure chamber. A supply passage for supplying a working oil from an external working oil source into said hydraulic pressure chamber extends through the gap. A leakage of the working oil from the hydraulic pressure chamber through the gap can automatically be compensated for by working oil supplied through the supply passage. Since the working oil leaks from and is supplied into the hydraulic pressure chamber through the gap, the leakage and supply of the working oil are kept in equilibrium.

Abstract: A shock absorber system for controlling the damping forces of shock absorbers comprising a drive apparatus for operating a piezo-actuator which is constructed by laminating a plurality of piezoelectric elements. The drive apparatus comprises a high-voltage generation circuit for generating a high voltage and a charging and discharging circuit for applying the high voltage, generated by the high-voltage generation circuit, to the piezo-actuator and for discharging an electric charge charged in the piezo-actuator due to the application of the high voltage thereto, the charging and discharging results in expansion and contraction of the piezo-actuator. Also included in the drive apparatus is an abnormality detection circuit for detecting a charging current or a discharging current passing through a charging or discharging current passage coupled to the piezo-actuator at the time of charging or discharging by the charging and discharging circuit.

Abstract: A suspension control system controls suspensions provided for wheels of a vehicle includes a driving condition detecting part for detecting a driving condition of the vehicle, and a determination part for determining whether or not the driving condition detected by the driving condition detecting part coincides with a predetermined driving condition. The suspensions are grouped into a plurality of groups. Also the system includes a control part for separately controlling the suspensions on the basis of the driving condition when the determination part determines that the driving condition does not coincide with the predetermined driving condition and for controlling the suspensions for each of the groups so that the suspensions in an identical group are set to an identical condition when the determination part determines that the driving condition coincides with the predetermined driving condition.

Abstract: A drive system of a piezo-type actuator for use in a motor vehicle, which piezo-type actuator is constructed with a piezoelectric device which is expandable and contractible in accordance with application of a voltage thereto. The drive system includes a voltage-increasing section for increasing an output voltage of a power source mounted on the motor vehicle so as to develop a drive voltage for the piezo-type actuator and a voltage-application section for applying to the piezoelectric device of the piezo-type actuator the drive voltage. Also included in the drive system is an abnormality detection section which is arranged so as to an abnormality of the drive voltage developed by the voltage-increasing section.