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: An air chamber (53) of a damping force adjusting mechanism (49) disposed in a hydraulic shock absorber (3) of a damping force adjusting type communicates with an air chamber (7) of an air spring through a tubular path (57). A free piston (51) is transferred in accordance with the pressure of the air chamber and a spool (46) is transferred to shift a damping force. The damping force presents a soft characteristic both on the extending side and on the retracting side in a usual status, presents a hard characteristic on the extending side and a soft characteristic on the retracting side when the pressure of the air chamber is high, and presents a soft characteristic on the extending side and a hard characteristic on the retracting side when the pressure of the air chamber (7) is low. The damping force can be obtained, which approximates the damping force control on the basis of a so-called sky-hook theory.

Abstract: A suspension control system includes a shock absorber adapted to be mounted between a vehicle body and a wheel axle and having a variable damping force, an actuator operatively connected to the shock absorber and adapted to adjust the damping force developed by the shock absorber, an accelerometer for detecting terrain conditions and outputting a corresponding terrain condition signal, and a controller including a detector for determining terrain conditions in response to the frequency of the terrain condition signal and adapted to control the actuator in response to the terrain conditions as determined. The controller is operable to increase the damping force by a predetermined amount over a predetermined period of time when the accelerometer determines that the terrain includes a bump.

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: The disclosed suspension control system includes actuators for adjusting damping forces of front and rear variable-damping force shock absorbers. Also provided are front and rear vertical acceleration detectors. Usual control for the actuators are performed on the basis of the vertical accelerations detected by the vertical acceleration detectors. A control signal adjustor is provided to adjust a control signal to be sent to the actuator for the rear shock absorber such that the damping force of the rear shock absorber is reduced when the vertical acceleration detected by the front vertical acceleration detector or a rate of change thereof exceeds a preset reference value.

Abstract: The flow of a hydraulic fluid caused by sliding movement of a piston is controlled through a sub-disk valve, a main disk valve and a disk valve to generate damping force. A coil is energized to urge a plunger in the valve closing direction against spring force from a spring, thereby adjusting the relief pressure of the disk valve and thus controlling the damping force. The pressure in a back-pressure chamber varies according to the relief pressure of the disk valve. Thus, the valve opening pressure of the main disk valve is also adjusted. An abrupt input is absorbed by relieving the pressure from the back-pressure chamber by deflection of the disk valve. Because “soft” damping force characteristics, which are often used, are maintained with a small electric current, the power consumption can be reduced.

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: In the suspension control apparatus of the present invention utilizing a PWM type proportional solenoid valve, in which a current in a form such that a dithering current is superimposed on a target current is applied to a solenoid, when the average intensity of the applied current falls outside a predetermined range, a ratio between a time period during which the PWM signal having a decrease duty ratio is applied and a time period during which the PWM signal having an increase duty ratio is applied is changed so that an amplitude of the dithering current can be maintained at a predetermined level. Therefore, an undesirable increase in hysteresis with respect to a damping force can be suppressed, to thereby ensure good reponsivity for controlling a damping force, regardless of the average intensity of the applied current.

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: In the suspension control apparatus of the present invention, a CPU determines a desired damping force, based on an acceleration of a car body in a vertical direction, which is detected by an acceleration sensor, and also determines a PWM duty ratio corresponding to an intensity of a target current (an average intensity of the applied current) required for generating the desired damping force. Further, the CPU detects a voltage provided by a battery and adjusts the PWM duty ratio, based on the detected voltage value, so as to maintain a dither amplitude at a predetermined level. A PWM signal having the adjusted duty ratio is outputted to a transistor, to thereby apply a current which is obtained by superimposing a dither on the target current.

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: The disclosed suspension control system includes actuators for adjusting damping forces of front and rear variable-damping force shock absorbers. Also provided are front and rear vertical acceleration detecting devices. Usual control for the actuators are performed on the basis of the vertical accelerations detected by the vertical acceleration detecting devices. Control signal adjusting means is provided to adjust a control signal to be sent to the actuator for the rear shock absorber such that the damping force of the rear shock absorber is reduced when the vertical acceleration detected by the front vertical acceleration detecting device or a rate of change thereof exceeds a preset reference value.

Abstract: The present invention provides a suspension control apparatus including dither amplitude setting device which is adapted to set the amplitude of the dithering current to be superimposed on the command current is set to a small value in a region in which a damping force generated by the shock absorber changes at a high rate relative to changes in intensity of the current applied to the solenoid. The present invention also provides a suspension control apparatus including dither frequency setting device which is adapted to set the frequency of the dithering current to a high frequency in a region in which a damping force generated by the shock absorber changes at a high rate relative to changes in intensity of the current applied to the solenoid and set the frequency of the dithering current to a low frequency in a region other than the above-mentioned region.

Abstract: A suspension control system for a vehicle includes a plurality of hydraulic cylinders interposed between the vehicle body and the respective axles of front right, front left, rear right and rear left wheels for controlling the vehicle height by the action of a hydraulic fluid charged into and discharged from the cylinders. A plurality of normally-closed charge-discharge valves are provided to correspond to respective of the hydraulic cylinders. When the hydraulic fluid is to be charged into or discharged from the hydraulic cylinders, among the charge-discharge valves, at least the left and right charge-discharge valves associated with either the front right and front left wheels or the rear right and rear left wheels are not opened simultaneously, but either of the left and right charge-discharge valves is selectively opened.