Abstract: In a suspension control system, a controller previously stores damping force maps (an ordinary road map, a rough road map, and an extremely rough road map) corresponding to road surface conditions (an ordinary road, a rough road, and an extremely rough road) defined by frequency and amplitude of vertical acceleration. The frequency and amplitude of the vertical acceleration are detected, and a damping force map (the ordinary road map, the rough road map, or the extremely rough road map) corresponding to the detected information is selected. Damping force control is effected on the basis of the selected damping force map. Selection of a damping force map according to the frequency and amplitude of the vertical acceleration is also made when a change in the vertical acceleration, i.e. a change in piston speed, is predicted during running on an ordinary road, a rough road or an extremely rough road.

Abstract: By passing the vertical acceleration through a phase adjusting filter and a gain adjusting filter, the phase of the vertical acceleration is advanced by 49 degrees so that the phase difference with respect to the actual relative velocity becomes 180 degrees in the neighborhood of the vehicle body resonance point, thereby making the phase of the vertical acceleration, in effect, coincident with the phase of the relative velocity. In the neighborhood of the vehicle body resonance point (1 Hz), the gain of the estimated relative velocity takes a small value. In frequency regions other than the neighborhood of the vehicle body resonance point, the gain of the estimated relative velocity is increased. Consequently, the controlled variable in the neighborhood of the vehicle body resonance point increases, and the controlled variable in higher frequency regions decreases. Damping force is adjusted in correspondence to the controlled variable.

Abstract: In a suspension control system according to the present invention, a controller previously stores damping force maps (an ordinary road map, a rough road map, and an extremely rough road map) corresponding to road surface conditions (an ordinary road, a rough road, and an extremely rough road) defined by the frequency and amplitude of the vertical acceleration. The frequency and amplitude of the vertical acceleration are detected, and a damping force map (the ordinary road map, the rough road map, or the extremely rough road map) corresponding to the detected information is selected. Damping force control is effected on the basis of the selected damping force map. Selection of a damping force map according to the frequency and amplitude of the vertical acceleration is also made when a change in the vertical acceleration, i.e. a change in the piston speed, is predicted during running on an ordinary road, a rough road or an extremely rough road.

Abstract: By passing the vertical acceleration through a phase adjusting filter and a gain adjusting filter, the phase of the vertical acceleration is advanced by 49 degrees so that the phase difference with respect to the actual relative velocity becomes 180 degrees in the neighborhood of the vehicle body resonance point, thereby making the phase of the vertical acceleration, in effect, coincident with the phase of the relative velocity. In the neighborhood of the vehicle body resonance point (1 Hz), the gain of the estimated relative velocity takes a small value. In frequency regions other than the neighborhood of the vehicle body resonance point, the gain of the estimated relative velocity is increased. Consequently, the controlled variable in the neighborhood of the vehicle body resonance point increases, and the controlled variable in higher frequency regions decreases. Damping force is adjusted in correspondence to the controlled variable.

Abstract: When a hydraulic cylinder apparatus operates in a direction such that the same damping force as a skyhook damping force cannot be produced, a command signal is applied so as to operate an active system (a fluid supply/discharge valve) and supply or discharge a fluid relative to the hydraulic cylinder apparatus, to thereby provide compensation of the damping force and obtain a desired damping force (shock-absorbing function). It is unnecessary to continuously supply or discharge the fluid through the active system and energy consumption can be reduced as compared to a conventional active control.

Abstract: When a road surface is judged to be undulating and rough, a parameter for a bad road to attain “soft” damping force characteristics is set with priority to setting of a parameter for an undulating road to attain “hard” damping force characteristics. Consequently, “soft” damping force characteristics are obtained to improve the ride quality. This order of the priority is adopted especially when a vehicle speed is low. When the vehicle speed is high, the order of the priority is reversed.

Abstract: In the suspension control apparatus of the present invention, when a lateral acceleration differential value falls outside a lateral acceleration differential value range, a controller calculates a control input for an actuator, based on the lateral acceleration differential value, in preference to a lateral acceleration. Therefore, immediately after the start of rolling of a vehicle and just prior to the end of the rolling when the lateral acceleration differential value falls outside the lateral acceleration differential value range, the control input for the actuator is calculated based on the lateral acceleration differential value.

Abstract: A suspension control apparatus includes a variable damping coefficient type shock absorber disposed between sprung mass and unsprung mass of a vehicle and an actuator for setting and adjusting a damping coefficient of the variable damping coefficient type shock absorber on the basis of a control signal. An upward and downward absolute velocity detector for detecting an upward absolute velocity and a downward absolute velocity of the vehicle is provided. A control unit changes a signal from the upward and downward absolute velocity detector in accordance with a running condition of the vehicle to obtain a control target signal. A control signal generator outputs the control signal for the actuator on the basis of the control target signal from the control unit.

Abstract: The present invention provides a suspension control apparatus which can perform good suspension control regardless of change in temperature. The suspension control apparatus comprises a transistor capable of being turned ON/OFF in response to a level of a PWM signal, a current sensor for detecting current flowing through a proportional solenoid, and a controller for adjusting a duty ratio of the PWM signal on the basis of the comparison between a current data detected by the current detecting means and a previously set reference data to correct command current. The current actually flowing through the proportional solenoid is measured, and the duty ratio of the PWM signal is adjusted to obtain a desired damping force on the basis of the measured current. With this arrangement, if a temperature of the proportional solenoid is increased to increase resistance thereof due to application of current to the proportional solenoid, the applied current is corrected to provide the desired damping force.

Abstract: A suspension control system for a vehicle enables excellent ride quality and excellent running stability to be obtained even when the vehicle is running on a bad road. When a road surface condition judging circuit judges that the vehicle is running on a bad road, a damping coefficient preferential setting circuit preferentially sets the compression-side damping coefficient of a damping coefficient varying type shock absorber to a predetermined large value, and consequently sets the extension-side damping coefficient to a small value. Thus, the ride quality is prevented from being degraded by control delay. Further, uncontrollable movement of non-suspended members is effectively suppressed, and thus the condition of contact between the wheels and the ground is improved. Accordingly, even if the vehicle is steered during running on a bad road, no drift-out occurs. Thus, excellent running stability can be ensured.

Abstract: The present invention provides a suspension control apparatus for a vehicle ensuring good comfort regardless of a waving road surface condition. A control signal adjusting portion sends a control signal for decreasing a damping coefficient for an extension side to a control signal emitting portion when an absolute value of downward acceleration of sprung mass exceeds a sprung mass acceleration reference value. When the vehicle reaches the top of an undulation and the absolute value of the downward acceleration of the sprung mass exceeds the sprung mass acceleration reference value, the control signal adjusting portion sends the control signal for decreasing a damping coefficient for the extension side to the control signal emitting portion so that a shock absorber of variable damping coefficient type can easily be displaced toward the extension side.

Abstract: The present invention provides a suspension control device with which the damping coefficient of the suspension can be easily adjusted on the basis of only the vertical vibration of a body of a vehicle, without measurement of the relative velocity or the relative displacement between the body and the wheel along the vertical direction. The absolute velocity of the body 1 is calculated on the basis of the detected signal of the acceleration sensor attached to the body 1, then the rotation angle .theta. of the movable plate is calculated on the basis of the absolute velocity, and the movable plate is rotated in the predetermined direction by the rotation angle .theta.. Accordingly, the damping coefficient is adjusted so that the coefficient in the extension of the shock absorber becomes larger and the coefficient in the compression of the shock absorber becomes smaller, or so that the damping coefficient in the extension becomes smaller and the coefficient in the compression becomes larger.

Abstract: A suspension system for a vehicle which has a hydraulic cylinder that extends and retracts in accordance with a change in the distance between a vehicle body and an axle to vary the volumetric capacity of a working chamber defined therein, an accumulator connected to the working chamber in the hydraulic cylinder, a control valve controlling the flow rate of oil charged into and discharged from the accumulator and the hydraulic cylinder, and a vehicle level sensor detecting a change in the above-described distance. The suspension system further has a control unit that controls the control valve, on the basis of a flow control signal obtained by multiplying the detected signal from the vehicle level sensor by an amplification factor, so as to restore the vehicle to a neutral state. The control unit is arranged to increase the amplification factor when the amount of the extension or retraction of the hydraulic cylinder is close to the extent of the full stroke thereof.

Abstract: A suspension control system for controlling the attitude of a vehicle such as an automobile includes a suspension unit including a hydraulic cylinder disposed between an axle and the body of the vehicle and an accumulator connected to the hydraulic cylinder, a pressurized hydraulic fluid source, a hydraulic fluid supplying and discharging valve operatively connected to the suspension unit and to the hydraulic fluid source and a controller for controlling the hydraulic fluid supplying and discharging valve to supply or discharge hydraulic fluid to or from the suspension unit. The suspension control system further includes a pressure sensor for detecting the pressure in the suspension unit. The controller also prevents hydraulic fluid from being discharged from the suspension unit when the pressure in the suspension unit is lower than a predetermined value.

Abstract: A tow device is mounted between two structural members of a vehicle which share in absorbing a moment of force transmitted through the device when the vehicle is towed. One of the structural members is substantially normal to the axis about which the moment of force acts to provide resistance to structural deformation, while permitting the device to project below the vehicle body proper to prevent accidental impacting of the vehicle underbody on the road.