Active vehicle suspension system

#The invention relates to an active suspension system, particularly for vehicles, having supporting units, which each have an actively lift-adjustable regulating unit and a passive spring arranged in series thereto, and having an automatic control of the regulating units, a path sensor for generating a signal correlated with the lifting position of the supporting unit being assigned to each supporting unit, and an arrangement of acceleration sensors being provided on the vehicle body for generating signals for body-side longitudinal and lateral accelerations as well as lifting movements, and control signals used for controlling the regulating units comprising a first proportion generated by signals of acceleration sensors and a second proportion generated by signals of path and acceleration sensors.

#A suspension system of the type generally described above is the object of German Patent Document DE 39 32 476 A1. According to this document, hydropneumatic spring and supporting units are provided in the case of which the passive spring is formed by a pneumatic spring loading device. This spring is hydraulically connected with a piston working space of a piston-cylinder unit arranged between the sprung and the unsprung mass, in which case the hydraulic "linkage" formed by the hydraulic connection can be lengthened or shortened by the feeding or removal of hydraulic medium.

#The first proportion of the control signals is determined by the longitudinal and lateral acceleration by the vehicle body. The second proportion of the control signals depends on the lifting path of the unsprung mass relative to the sprung mass as well as the vertical acceleration of the sprung mass.

#FIG. 1 is a schematic view of a supporting unit used in the present invention;

#FIG. 2 is a schematic view of a vehicle having a suspension system according to a preferred embodiment in the present invention; and

#FIG. 3 is a block diagram of the automatic control for the lift-adjustable regulating units.

#A supporting unit 3 in each case arranged between a wheel 1 and the chassis or body 2 of a vehicle has a passive spring 4 as well as a hydraulic unit 5 which is arranged in series thereto and which is provided in FIG. 1 according to a preferred embodiment of the invention on the vehicle body side with respect to the spring 4. The vehicle-body-side abutment of the spring 4 can be vertically adjusted relative to the vehicle body 2 via the hydraulic unit 5.

#A damper 6 is arranged between the wheel 1 and the vehicle body 2 in parallel to the spring 4 or, as illustrated in FIG. 1, in parallel to the spring 4 and the hydraulic unit 5. The illustrated arrangement of the damper 6 therefore offers an advantage in that the damper 6 can be constructed with a larger length than would be the case if the damper 6 were arranged only in parallel to the spring 4 between the wheel 1 and the hydraulic unit 5. Nevertheless, this latter arrangement is also contemplated and is also advantageous because then, in the case of an adjustment, the supporting unit 3 need not work against the resistance of the damper 6.

#In a controllable manner by way of an electrically operated proportional valve arrangement 7, the hydraulic unit 5 can be connected with a hydraulic pressure source 8, which may be constructed as a hydraulic pressure accumulator continuously held at an approximately constant pressure by way of a hydraulic pump which is not shown, and/or with a relatively pressureless reservoir 9, or can be blocked with respect to the pressure source 8 as well as with respect to the reservoir 9, in which case a slight leakage may occur, however.