DE4003493A1 - Hydro-pneumatic suspension for vehicle - Google Patents

Abstract

The hydropneumatic suspension has the separate suspension units linked to a pumped high pressure reservoir which powers the self levelling control. A parallel control system is powered by a second pump (5) and a set of electromagnetically controlled valves (1 to 4) to adjust the suspension units w.r.t. dynamic conditions. The programmed control provides correction for brake dive and for rolling when cornering. The additional control system has a faster response time than the self levelling suspension. It only operates when its pump is running, and the pump only runs when required. A failsafe protection blocks the additional system if a fault is detected, enabling the vehicle to be driven with the conventional self levelling control.

Description

The invention relates to a hydropneumatic suspension system for motor vehicles with the vehicle wheels assigned neten hydropneumatic support units and one with it interacting level control, which is dependent from the stroke position of the wheels hydraulic medium from one Introduce reservoir in the support units or hydraulics discharge medium from the support units into the reservoir allowed.

Vehicles with such suspension systems are already mass-produced. These vehicles also stand out with a high level of suspension comfort.

A fundamental disadvantage of such suspension systems consists in the fact that energy for Must be made available, the hydraulic medium, which is introduced into a support unit, a high-pressure accumulator is removed, the pressure must be significantly higher than the highest pressure, which can ever occur in one of the support assemblies. The energy required for this is provided by the travel drive of the Motor vehicle removed and a corresponding Hydrau lik pump supplied. This energy goes with a follower level lowering, with the hydraulic medium from one Support unit is discharged into the reservoir, unused lost.  

To keep the power requirement for level control low is therefore to keep with known hydropneumatic Suspension systems provided, pitching and rolling movements the vehicle body with special measures to act without the increased burden Support units from the hydraulic medium reservoir must be supplied. For example, roll movements of the vehicle body despite a comfortable and soft Tuning the hydropneumatic suspension system in Keeping limits is usually the case with hydropneumatic sprung vehicles relatively strong mechani cal anti-roll bars arranged, which with respect to each other couple the wheels opposite the longitudinal axis of the vehicle in such a way that when deflecting or rebounding a wheel also on each opposite wheel a force in the same on or off suspension direction is exercised. Thus, when compressing a wheel also the support unit of the Vehicle longitudinal axis opposite other wheel in Compression direction claimed. Because of this mode of action the cross stabilizers can also with soft tuning of the Suspension system an excessively strong side tilt of the Vehicle body for fast cornering in the desired Way to be avoided. However, regarding the dimensioning of the transverse stabilizers can be compromised. If the cross stabilizers are very hard, is a side inclination of the Vehicle structure restricted particularly effectively. However, can the driving comfort when driving straight ahead on bad roads Roads are significantly impaired when lane bumps on one side of the vehicle offset to driving  bumps on the other side of the vehicle occur and accordingly one wheel on one side of the vehicle rebound and the opposite wheel on the on the other side of the vehicle. This opposite Suspension strokes look towards the anti-roll bars to act.

To avoid undesired pitching movements hydropneumatically suspended Largely vehicles even with soft spring tuning To be able to avoid have known hydropneumatic Suspension systems in addition to wheel-wise on the support units gates of the wheels arranged spring loaded axially ordered additional spring storage, which ver with shut-off valves are seen and therefore quickly ineffective if necessary can be. As long as the additional spring accumulators are active, the support units of one axle have a spring identification with little progressiveness, d. H. the respectively generated Support forces increase comparatively slowly when deflecting at. If, on the other hand, the auxiliary spring accumulator is deactivated there is a spring detection with a steep progression vity, d. H. the support units set a deflection stroke a resistance that increases sharply with the stroke. The changeover valves assigned to the additional spring accumulators can be controlled practically without inertia, so that the progressiveness of the spring detection on a vehicle axle can change accordingly quickly. That way it is For example, possible when braking or accelerating counteracting the pitching moment of the vehicle, by, for example, the additional spring storage when braking the front axle and the auxiliary spring when accelerating memory of the rear axle can be deactivated with the  Consequence that the suspension of the front axle or the suspension the rear axle is stiffened. That way they can Nodding movements of the vehicle body in the desired manner be limited. However, each must have an axle Stiffening of the suspension can be accepted.

The object of the invention is now a hydropneumatic To create suspension system, which is characterized by low Power requirement for pumping hydraulic medium as well as particularly high suspension comfort - also with Influence of strong pitching or rolling moments on the vehicle construction - excellent.

This object is achieved in that an active bypass and Conveyor system is arranged, which depending on the stroke position of the wheels and / or on the vehicle acting pitch or roll moments hydraulic medium Bypassing the reservoir between each other regarding the Vehicle longitudinal axis and / or the vehicle transverse axis opposite horizontal support units allowed to move.

The invention is based on the general idea directly between the support units of various Vehicle sides or the front and rear outrigger aggregates to move hydraulic fluid to a vehicle side while lowering the other side of the vehicle to raise or the front part of the vehicle in the corresponding To move in the opposite direction to the rear of the vehicle.  

Since according to the invention for this purpose a shift of Hydraulic medium provided bypassing the reservoir is, the necessary power requirement is low because it only the difference between the hydraulic Pressures are overcome in different support units, but not the much larger pressure difference between Reservoir and support units.

In addition, a particularly high level of comfort can be guaranteed be because the shift of the hydraulic medium between the support units have only a slight influence on the Has spring identification.

It is also advantageous in the invention that the level regulation sluggish, d. H. with low power, can work because this system to balance pitch and roll conditions of the vehicle is not required. Essentially this system just has to be able to start the vehicle in a reasonable time the desired or set a predetermined level. However, this is sufficient a very low performance, especially since it turned on set the level when the vehicle stopped changes when there is a drain of hydraulic fluid from the outrigger aggregates in the reservoir, for example by corresponding appropriate shut-off valves, can be prevented.

According to a first advantageous embodiment of the invention The bypass and conveying system can essentially be used a line arranged between the support units network with a motor-driven pump and on Shut-off valves arranged in the pipeline network exist  one support unit or one group of supports aggregate with the input side of the pump and another Outriggers or another group of outriggers connect aggregates to the output side of the pump or the support units or their groups from each other allow to separate. With this arrangement, it is therefore sufficient one central for the bypass and conveyor system Pump. By controlling the valves accordingly then a shift of hydraulic medium between selected support units can be reached. By a Type of multiplex operation can also be achieved that a practically simultaneous shift of hydraulics medium between a variety of support units in controllable way.

In a second preferred embodiment of the invention are between each other with respect to the vehicle transverse axis and / or the support opposite the longitudinal axis of the vehicle aggregates displacement or piston-cylinder units with two chambers arranged, the total volume independent of the displacer or piston stroke remains constant, so that the on the one hand from a support unit or one Hydraulic fluid group discharged into support units the same amount another support unit or one other group of support units can be supplied.

Regardless of the formation of the bypass and conveyor system it may be appropriate to use the hydropneumatic support aggregates parallel to mechanical spring units, for example as conventional coil springs to arrange so that the Wheels compared to the body hydropneumatic and  mechanically supported. This way one can almost load-independent suspension behavior of the vehicle without change in resonance frequencies for Lifting movements of the body (body resonance) or lifting vibrations against the wheels (wheel resonance).

Otherwise, the Erfin to the claims and the following explanation preferred embodiments with reference to the drawing.

It shows

Fig. 1 shows a first embodiment of the suspension system of the invention, wherein the bypass and delivery system by a cable network having a plurality of check valves and a single central pump is formed,

Fig. 2 shows a second embodiment of the invention, in which the bypass and conveyor system is constructed using double-acting, a two-circuit system forming piston-cylinder units, which are each arranged between the support units ver different vehicle sides or different axes and

Fig. 3 shows another embodiment with double-acting piston-cylinder units with a particularly simple structure.

In all the embodiments shown in the drawing, each wheel R of the vehicle is assigned a hydropneumatic support unit A, which in a manner known per se essentially consists of a piston-cylinder unit with a cylinder Z and a piston K with a piston rod S arranged on one side and the piston K exists axially through settling bores B and a spring accumulator F connected to the cylinder Z. The cylinders Z are filled on both sides of the associated piston K with hydraulic medium, as is the area of the respective spring accumulator F that communicates with the respective cylinder Z. Inside the spring accumulator F there is also a pressure gas cushion D which is separated from the hydraulic medium by an elastic Membrane or the like. Is separated. When the wheels R move in and out, the respective piston K is displaced in the associated cylinder Z. With a displacement in the direction of compression, hydraulic medium from the chamber of the cylinder Z in FIGS . 1 to 3 above the piston K through the piston-side bores B into the other chamber of the piston-cylinder unit and partly also in the respective one Spring accumulator F displaced so that the respective compressed gas cushion is compressed. When the piston K is displaced in the rebound direction, hydraulic medium is displaced from the piston rod-side chamber of the respective piston-cylinder assembly into the chamber above the piston K, at the same time hydraulic medium flows from the respective spring accumulator F into this latter chamber, the pressure gas cushion D of the respective spring accumulator expanded accordingly.

The respective static support force of the support units A is determined by the pressure of the hydraulic medium in the piston Cylinder unit and the associated spring accumulator F and the cross section of the piston rod S or the surfaces difference between the upper and lower effective area of the respective piston K determined.

The average height of the wheels R relative to not Darge The structure of the vehicle is determined by the amount of Hydraulic medium in the support units A determined.

In order to be able to change the amount of hydraulic medium in the support assemblies A for level control of the vehicle, the support assemblies A can be shut off to the outside via level control valve tile N or connected either to a reservoir or reservoir V fluid medium or to the pressure side of a pump P, with which the respective support unit A is then supplied with hydraulic medium from the reservoir or reservoir V. In order to avoid pressure surges, an additional spring accumulator F _{P is} arranged on the pressure line of the pump P.

The support units A of the front wheels (which are shown in FIGS . 1 to 3 in the upper part) can each be assigned a separate level control valve N, which is actuated as a function of the stroke position x _vr or x _{vl of} the respective wheel. The level control valves N of the support units A of the front wheels are closed in a relatively wide middle range of the mentioned stroke positions. When star ker displacement of the wheels R or piston K in Ausfederrich device, the respective support unit A is connected to the reservoir or reservoir V to derive hydraulic medium from the respective support unit A and thus to move the respective wheel R in the direction of deflection. If the wheels R or the respective pistons K move strongly in the direction of deflection, the level control valves N establish a connection between the pressure side of the pump P and the respective support unit A in order to introduce additional hydraulic medium into the respective support unit A and the respective wheel R in To move the rebound direction.

The vehicle rear wheels (shown in FIGS. 1 to 3 in the lower part) is assigned a common level control valve N, which is controlled depending on the arithmetic mean of the stroke positions x _hl and x _{hr of} the rear wheels R. This ensures that the vehicle always receives a statically clear three-point support.

When using a sufficiently strong stabilizer sators for recording the rolling moments when cornering or asymmetrical vehicle loading, can also on the Control both front support units A together at the front axle of the level control valve N are provided, whereby the Vehicle a "two-point support with mechanical roll feather ".  

In order to enable control of the level control valve N assigned to the rear wheels R as a function of the mean value of the stroke positions x _hr and x _hl , the ends of a yoke J are, for example, coupled to the wheel suspensions of the rear wheels R, so that one end of the yoke is one Suspension strokes of one rear wheel and the other end of the yoke J perform a translatory movement corresponding to the suspension strokes of the other rear wheel. If a point of the yoke J is now connected in the middle between the ends of the yoke J to an actuator of the rear level control tile N, this valve N is controlled as a function of the desired mean value.

Another way of averaging the stroke positions x _hr and x _{hl of} the rear wheels is possible by tapping for controlling the common level control valve N in the middle of a torsion bar stabilizer, not shown.

In which the support units A of the rear wheels R connecting line can be on both sides of the level control valves N of the rear wheels chokes T may be arranged, an undamped and fast flow of hydraulics medium from one to the other support unit A and thus an undesirably strong reaction of the suspension strokes of a rear wheel on the suspension movements of the to avoid another rear wheel.

The above-described design of the hydropneumatic suspension system is provided in the embodiments shown in FIGS . 1 to 3 in principle in the same way and - known per se. In this respect, the invention does not differ from conventional hydropneu matic suspension systems.

The special feature of the invention lies primarily in the type and manner, such as pitching or rolling movements of the vehicle body is counteracted.

Basically, it is possible to do so, as described above elements of the hydropneumatic suspension system to use. However, the pump P then becomes high Performance needed because of the pitch and roll movements of the Construction - without additional measures - only then can be counteracted if with the pump P for a short time relatively large amounts of the hydraulic medium from the reservoir or reservoir V to each strong in the direction of compression claimed support units A can be promoted. Here must always be at least the full pressure difference between the hydrau  lik pressure in the support units A and practical disappearing hydraulic pressure in the reservoir or Storage container V can be overcome.

According to the invention it is therefore provided that described above system components only for setting the average height of the vehicle body relative to Roadway. A pump P is sufficient for this purpose with low power because the middle altitude of the Vehicle can be set practically only at the start must and then remains unchanged or not a quick one Change required.

To make the vehicle pitch and roll quickly and To be able to counteract effectively is between the outriggers aggregates A a separate, active bypass and conveyor system arranged.

This consists in the embodiment shown in Fig. 1 consists essentially of a line network with the leading to the individual support units A lines 1 to 4 , the lines 1 ', 1 ''to 4 ', 4 '' with the input side of a motor-driven Pump 5 arranged shut-off valves 1 e to 4 e or the outlet side of the pump 5 arranged shut-off valves 1 a to 4 a are connected.

As long as no rolling or pitching movements of the vehicle occur, the valves 1 a to 4 e remain closed. In this case the pump 5 is stopped.

If pitching movements of the vehicle now occur, the same can be counteracted by the pump 5 depending on the direction of the pitching movement either discharging hydraulic medium from the support units A of the rear wheels via lines 3 and 4 and the support units A of the front wheels via lines 1 and 2 feeds or takes effect in the opposite direction. For example, if hydraulic medium is to be discharged from the support unit A of the right rear wheel and hydraulic medium is to be supplied to the support unit A of the right front wheel at the same time, the valves 4 e and 1 a are opened, so that the support units mentioned are connected to one another via the pump 5 and hydraulic medium in the specified way between the support units A is shifted to the right side of the vehicle. The other shut-off valves remain closed.

Beneficial for the energy consumption of the active bypass and Conveyor system is when its drive after Reaching a corresponding "final state", i. H. after this an amount corresponding to the respective driving conditions Hydraulic medium has been pumped around (e.g. with stationary Cornering), can be switched off and - as long as the driving state does not change - in this switched off Position remains without the pumped hydraulic medium back into its originally associated support units can flow.  

If hydraulic medium is removed from the front right support unit A and is to be fed into the rear right support unit A, the valves 1 e and 4 a are opened so that the pump can generate a flow of the hydraulic medium in the desired manner.

In basically the same way, the support units A can be connected to one another via the pump 5 on the left-hand side of the vehicle.

In addition, roll movements of the vehicle can be counteracted by supplying hydraulic medium from a support unit A of a wheel on one side of the vehicle by means of the pump 5 to a support unit A of a wheel on the other side of the vehicle. For example, hydraulic medium can be introduced from the right front support unit A into the left front support unit A by opening the valves 1 e and 2 a.

If the displacement of the hydraulic medium is to take place in the opposite direction, the valves 2 e and 1 a are opened.

The pump 5 only needs to work against the difference in the hydraulic pressures in different support units A. Since this difference always remains relatively small, a low output is sufficient for the pump 5 .

In order to move precisely defined quantities between the support units A, the valves 1 a to 4 e are preferably controlled in multiplex mode, such that only one of the valves 1 e to 4 e and one of the valves 1 a to 4 a are opened simultaneously are. Accordingly, only two support units A are coupled to each other via the pump 5 . By rapidly changing the open pairs of the opened valves 1 a to 4 e in cycles, it is then possible to carry out overlapping movements of hydraulic medium between any units A simultaneously. For example, on the one hand hydraulic medium can be removed from the right rear support unit and fed to the right front support unit, and on the other hand hydraulic medium can also be shifted in the same direction between the two left support units. For this purpose, the valve pairs 3 e, 2 a and 4 e, 1 a are alternately opened and closed in quick succession.

The control of the valves 1 a to 4 e is carried out with the support of a computer, not shown, which evaluates the signals from the stroke position sensors assigned to the wheels R in order to be able to determine pitch or roll movements of the vehicle. In addition, the computer can also receive signals from the accelerator pedal or engine of the vehicle and from the brake system of the same, in order to be able to "notice" the tendency to pitch movements that occur when braking or accelerating the vehicle even before such a movement. An anticipated pitching movement can thus already be counteracted by correspondingly controlling the valves 1 a to 4 e.

In addition, the computer can be connected to a steering angle sensor and a speedometer of the vehicle in order to accelerate the transverse acceleration of the vehicle and thus the tendency of the vehicle to assume a position inclined towards the outside of the curve as soon as cornering or the beginning of a steering movement to be able to determine. So that the computer can preventively control the valves 1 a to 4 e so that the vehicle does not or only slightly tends to the outside of the curve. Basically, it is also possible to force an inclination of the vehicle towards the inside of the curve by discharging a corresponding amount of hydraulic medium from the support units A on the inside of the curve and supplying units A to the outside support units.

A special advantage of the bypass and conveyor system is in that when controlling pitching and rolling movements the tuning of the suspension system practically remains unchanged.

In the embodiment of the invention shown in Fig. 2, the support units A via the lines 1 'to 4 ' with a motor-driven piston-cylinder unit 6 and via lines 1 '' to 4 '' with a motor-driven piston-cylinder - Unit 7 connected.

Each of the piston-cylinder units 6 and 7 has four chambers 61 to 64 and 71 to 74 , in the case of the piston-cylinder unit 6 in the central position of the piston, at least the chambers 61 and 62 on the one hand and the chambers 63 and 64 on the other have the same size (as a rule, all the chambers 61 to 64 are the same size), while in the piston-cylinder unit 74 all the chambers 71 to 74 are the same size in the central position of the piston. Otherwise, the piston-cylinder units 6 and 7 are designed so that the total volume of the chambers remains constant when the pistons are displaced.

The chambers of the piston-cylinder units 6 and 7 are each connected to one of the support units A, in such a way that when the piston of the piston-cylinder units gates 6 , hydraulic fluid is th between the support units on the right side of the vehicle and the support units on the left side of the vehicle. For example, when the piston of the piston-cylinder unit 6 is moved to the left, hydraulic medium is discharged from the front right support unit via line 1 'and at the same time hydraulic medium is introduced via line 2 ' into the left front support unit. On the other hand, a corresponding shift of the hydraulic medium takes place via lines 4 'and 3 ' in the support units of the rear wheels.

In this way, the side of the vehicle can be tilted change or counteract a roll movement.

The chambers 71 to 74 of the piston-cylinder unit 7 are connected to the lines 1 '' to 4 '', in such a way that a displacement of the hydraulic medium between the support units of the front wheels and those of the rear wheels is made possible. For example, with a displacement of the piston of the piston-cylinder unit 7 in Fig. 2 upward hydraulic medium from the rear support units via lines 3 '' and 4 '' is removed and at the same time the front support units via lines 1 '' and 2 ''Hydraulic medium supplied. In this way, a pitching movement of the vehicle can be counteracted.

Deviating from the embodiment shown in FIG. 2, in which the piston-cylinder units 6 and 7 each have four chambers, piston-cylinder units with two chambers can also be arranged in pairs and operated in parallel. This does not change the function shown.

In addition, hydrostatic pumps with a rotating displacement mechanism in the manner of gear pumps or vane pumps could also be provided instead of the piston-cylinder units shown in FIG. 2. So that in this case several hydraulic circuits are available to support the roll moments that occur on both vehicle axles accordingly by pumping over hydraulic medium, two hydrostatic pumps can be mechanically coupled, which have the same delivery rate if the roll moments are absorbed by about half of the front and rear axles should be.

In the embodiment of the inven tion shown in Fig. 3 three piston-cylinder units 8 to 10 , each with two chambers 81 , 82 and 91 , 92 and 101 , 102 are arranged. The chambers 81 and 91 of the piston-cylinder units 8 and 9 are connected via lines 1 and 2 to the front support units A. The rear support units A are on the lines 3 'and 4 ' on the one hand with the chambers 82 and 92 of the piston-cylinder units 8 and 9 and on the other hand via the lines 3 '' and 4 '' with the chambers 101 and 102 of Piston-cylinder unit 10 connected. In the middle position of the pistons, the chambers 81 , 82 , 91 and 92 have the same size. The chambers 101 and 102 in the central position of the piston of the piston-cylinder unit 10 are equal to one another and approximately twice as large as the chambers of the two other piston-cylinder units 8 and 9 in the central position of the respective pistons.

If the piston of the piston-cylinder unit 10 is kept still and the pistons of the piston-cylinder units 8 and 9 are simultaneously moved up or down in FIG. 3, hydraulic medium is shifted between the front and rear support units. When moving the pistons of the piston-cylinder units 8 and 9 upwards, for example, hydraulic medium is discharged from the rear support units via lines 3 'and 4 ' and, at the same time, hydraulic medium is fed to the front support units via lines 1 and 2 . In this way, pitching movements of the vehicle can be counteracted.

In order to change the side inclination of the vehicle or to counteract rolling movements of the vehicle, hydraulic medium can be moved between the support units of different vehicle sides, for example by the piston of the piston-cylinder unit 8 downwards, the piston of the piston-cylinder unit 10 right and the piston of the piston-cylinder unit 9 is shifted upward (or in the opposite direction). Since the capacity of the piston-cylinder unit 10 is approximately twice as large as that of the piston-cylinder unit 8 or 9 , the chamber 101 of the piston-cylinder unit 10 can in addition to that from the chamber 82 of the Piston-cylinder unit 8 displaced hydraulic medium also absorb a corresponding amount of the hydraulic medium from the support unit of the left rear wheel (bottom left in Fig. 3). In a corresponding manner, about half of the hydraulic medium displaced from the chamber 102 of the piston-cylinder unit 10 can be introduced into the support unit of the right rear wheel (bottom right in FIG. 3) and approximately half from the chamber 92 of the piston-cylinder Aggregates 9 are included. At the same time, hydraulic medium is displaced from the chamber 91 of the piston-cylinder unit and fed via line 1 to the support unit of the right front wheel.

Even if it is usually not necessary, the system shown in FIG. 3 enables hydraulic medium to be moved only between the support units of the front wheels or the support units of the rear wheels.

To shift hydraulic medium between the support units of the rear wheels, it is sufficient to stop the pistons of the piston-cylinder units 8 and 9 and to move the piston of the piston-cylinder unit 10 . When moving the piston of the piston-cylinder unit 10 to the right, hydraulic medium is discharged via line 3 '' from the support unit of the left rear wheel and simultaneously introduced via line 4 '' hydraulic medium into the support unit of the right rear wheel.

If, for example, hydraulic medium is now discharged from the support assembly of the right front wheel via line 1 and at the same time hydraulic medium is to be introduced into the support assembly of the left front wheel, the piston of the piston-cylinder unit 9 in FIG. 3 is down, the piston of the piston -Cylinder unit 10 to the left and the piston of the piston-cylinder unit 8 moved upwards, in such a way that the volume reduction of the chamber 92 of the piston-cylinder unit 9 of the volume increases the chamber 102 of the piston-cylinder unit 10 and the reduction in volume of the chamber 101 of this piston-cylinder unit 10 correspond to the increase in volume of the chamber 82 of the piston-cylinder unit 8 .

In the event of a fault in the bypass and conveyor system, in particular in the event of malfunctions in the computer controlling this system, is preferably provided below the bypass and conveyor system To block the blocking of its lines. After that, then be continued, the vehicle itself as such behaves with conventional hydropneumatic suspension system.

In the embodiment shown in Fig. 1, the pump 5 are stopped and all valves 1 a to 4 e closed in the event of such a fault. For this purpose, it is advantageous if the valves 1 a to 4 e automatically, for. B. springs by return are brought into the closed position as soon as the electromagnets used to control the valves 1 a to 4 e are switched off.

To form a corresponding emergency operation of the vehicle in the embodiment shown in FIGS. 2 and 3, it is sufficient to have the piston-cylinder units 6 to 10 with self-locking drives, for. B. spindle units, so that the pistons of these units are kept immovable when switching off the drives.

To the extent that rotating pumps are used instead of the piston-cylinder units 6 to 10 in FIGS. 2 and 3, such pumps, e.g. B. gear pumps, preferred, which can block the connection between the input and output of the pump without additional shut-off valves when the pumping element of the pump is stopped. If such pumps are provided with self-locking drives, it is sufficient to shutdown or switch off the drives in order to block the lines of the bypass and delivery system in the event of a fault.

If necessary, however, separate ones can also be used for this purpose Shut-off valves can be arranged.

A particular advantage of the invention is that with the Bypass and conveyor system also the control tendency - sub steer, oversteer or neutral behavior - the driving Stuff can be influenced or determined. For example can counter the vehicle's rolling movements in the way be placed on the front and rear axles under differently sized, counteracting the roll movement moments are generated relative to the vehicle's longitudinal axis, by the one between the support units the front axle and on the other hand between the support units  Gaten shifted amounts of hydraulics on the rear axle mediums accordingly - if necessary also strongly below different - are measured.

In order, for example, in the embodiment according to FIG. 2 to be able to generate significantly different counter torques to compensate for rolling moments of the vehicle on the front and rear axles, the hydraulically effective cross sections of the pistons in the chambers 61 and 62 on the one hand and 63 and 64 on the other hand can be dimensioned significantly differently be. As a rule, it is desirable to counteract rolling moments to a greater extent via the front axle; accordingly, the effective piston cross section in the chambers 61 and 62 will generally be larger than in the chambers 63 and 64 .

Claims (9)

1. Hydropneumatic suspension system for motor vehicles with the hydropneumatic support assemblies assigned to the vehicle wheels and a level control interacting therewith which, depending on the lifting position of the wheels, allows hydraulic medium to be introduced from a reservoir into the support assemblies or hydraulic fluid to be discharged from the support assemblies into the reservoir, characterized in that An active bypass and conveying system is arranged between the support units (A), which is a function of the stroke position (x _vr , x _vl , x _hr , x _hl ) of the wheels (R) and / or a function of pitch acting on the vehicle - Or rolling moments hydraulic medium bypassing the reservoir (R) between each other with respect to the vehicle longitudinal axis and / or the vehicle transverse axis opposite support units (A) allowed to move. 2. Hydropneumatic suspension system according to claim 1, characterized in that the bypass and conveyor system fast-acting and the level control in comparison work slowly on the bypass and conveyor system.   3. Hydropneumatic suspension system according to one of claims 1 or 2, characterized in that the bypass and conveying system consists essentially of a line network arranged between the support units (A) with a motor-driven pump ( 5 ) and shut-off valves arranged on the line network ( 1 a , 1 e to 4 a, 4 e), which each have a support unit (A) or a group of support units with the input side of the pump ( 5 ) and another support unit or another group of support units with the output side of Allow the pump ( 5 ) to be connected or to separate the support units or the groups of the support units. 4. Hydropneumatic suspension system according to one of claims 1 or 2, characterized in that between each other with respect to the vehicle transverse axis and / or the vehicle longitudinal axis opposite support units (A) displacement or piston-cylinder units ( 6 , 7 ) each with at least two chambers are arranged, the total volume of which remains constant irrespective of the displacer or piston stroke, one of the chambers being connected to a support unit on one side and the other of the chambers being connected to a support unit on the other side of the vehicle longitudinal axis or the vehicle transverse axis. 5. Hydropneumatic suspension system according to one of claims 1 to 4, characterized in that the bypass and conveyor system by means of a computer in dependence on the stroke positions (x _vr , x _vl , x _hr , x _hl ) of the wheels (R) and / or depending on the longitudinal or lateral acceleration of the vehicle and / or in dependence on the steering angle or steering angle changes and the driving speed of the vehicle is controllable. 6. Hydropneumatic suspension system according to one of the Claims 1 to 5, characterized in that parallel to the hydropneumatic support units (A) mecha African spring units are arranged. 7. Hydropneumatic suspension system according to one of claims 1 to 6, characterized in that the conveying units ( 6 to 10 ) of the bypass and conveying system have self-locking drives and keep the lines connected to them at a standstill separated from one another. 8. Hydropneumatic suspension system according to one of the Claims 1 to 7, characterized in that the Bypass and conveyor system for compensation or prevention change of rolling movements of the vehicle between the Support units (A) of the front axle and between the Support units (A) of the rear axle dimensioned in this way Amounts of the hydraulic medium that shifts to the front and rear axle different, the rolling moment of the Counteracting moments are generated and a desired tax trend (understeering, Oversteer, neutral behavior) of the vehicle is achieved.   9. Hydropneumatic suspension system according to one of the Claims 1 to 8, characterized in that the Drive motor for the bypass and conveyor system in can be switched off in any position and remains in this position without energy consumption, the hydraulic medium even with large ones Differences in pressure during this switched off Condition in the bypass and conveyor system not shifted can be.