In a vehicle suspension apparatus having air spring chambers between the vehicle body and the respective wheels to perform height and position control modes by controlling supply control valve means for supplying air to the air spring chambers and exhaust control valve means for exhausting air from the air spring chambers, the vehicle suspension apparatus has a high-pressure reserve tank connected to the respective chambers through the supply control valves, a first compressor for supplying compressed air to the high-pressure reserve tank, a low-pressure reserve tank connected to the respective chambers through the corresponding exhaust control valves and the suction port of the first compressor, and a second compressor for supplying atmospheric air to the high-pressure reserve tank through a check valve and a drier arranged between the check valve and the second compressor. In the position control mode, the compressed air is exhausted from the chambers to the low-pressure reserve tank through the exhaust control valves. In the height control mode, the compressed air is slowly exhausted from the corresponding chambers through the exhaust control valve means via the drier, thereby regenerating the drier during height down control.
A height regulation system for an automotive vehicle to generally adjust a vehicular height level within a predetermined height range includes a variable pressure chamber, in which the fluid pressure is adjusted to adjust the relative distance between the vehicular body and a vehicular wheel. The system includes a control circuit including a sensor for monitoring vehicular height for detecting an actual vehicular height beyond the predetermined height range for triggering height adjustment operation. The control circuit limits the variation range of the fluid pressure within a predetermined range so as to avoid excess adjustment of the pressure at any vehicular condition.
A vehicle fluid suspension circuit comprising fluid sources provided to the front and rear sides of a vehicle, front and rear side paths connecting the front and rear side fluid sources and fluid suspensions of right and left wheels of the respective sides and providing valves between the resepective fluid sources and fluid suspensions of respective wheels and a front-to-rear path having an effective sectional area which is smaller than the effective sectional areas of the front side path and rear side path, respectively, and connecting the front side fluid source with the rear side fluid source.
A hydraulic pressure supply system includes a discharge rate variable fluid pump. The discharge rate of the fluid pump is controlled to vary depending upon the vehicle driving condition. In the control of the discharge rate of the fluid pump, greater discharge rate is ordered while the vehicle is running, than that during vehicle stopping condition.
An electronically controlled fluid suspension system for adjusting a vehicle's attitude rapidly controls the vehicle height: by providing and blocking the fluid communication between fluid springs and reserve tanks; and by shifting the damping force of shock absorbers to a higher degree in response to the change of the vehicle height. As a result, it can avoid the late control of the vehicle height and prevent the vibration of the vehicle body due to the vehicle height's adjustment, thereby enhancing riding comfort.
When vibrations having a period at which pitching tends to occur in a vehicle body is detected, if its amplitude falls out of the range between "H" and "L", a control unit increases the damping force of each suspension unit by using an actuator. In addition, if the amplitude falls out of the range between "HH" and "LL", the control unit supplies a predetermined amount of air to each air spring chamber in response to an upward displacement of vehicle height, and exhausts a predetermined amount of air from each air spring chamber in response to a downward displacement of vehicle height.
