GB2315716A

GB2315716A - Device for the lateral stabilisation of a motor vehicle

Info

Publication number: GB2315716A
Application number: GB9714612A
Authority: GB
Inventors: Klaus Dipl Ing Vosteen; Thomas Dipl Ing Garbe
Original assignee: Amg Motorenbau & Entw GmbH
Current assignee: Amg Motorenbau & Entw GmbH
Priority date: 1996-07-27
Filing date: 1997-07-14
Publication date: 1998-02-11
Also published as: IT1293733B1; DE19630442C1; ITMI971709A1; FR2751591A1; GB9714612D0

Abstract

A device for lateral stabilisation of a motor vehicle comprises for each telescopic strut unit (1, 2) associated with a wheel a piston-cylinder unit (15, 16), the piston rod (17, 18) of which is in connection with the free movable end of the associated telescopic strut unit (1, 2) in such a way that it follows the movement thereof, especially during springing. The piston-cylinder units (15, 16) on opposite sides of the motor vehicle are connected to one another by an arrangement (21a, 22a, 23, 24) so that a movement of the piston rod (17) of the one piston-cylinder unit (15), which happens as a result of springing of the associated telescopic strut unit (1), introduces pressure medium into a cylinder chamber (22b) of the opposite piston-cylinder unit (16). Because of this, the piston rod (18) of that second piston-cylinder unit (16) is likewise extended for the purposes of shortening the telescopic strut unit (2) associated with it.

Description

2315716 DEVICE FOR THE LATERAL STABILISATION OF A MOTOR VEHICLE This

invention relates to a device for lateral stabilisation of a motor vehicle.

If a motor vehicle, for example a racing car, is negotiating a bend at high speed, then the wheels that are outermost in relation to the midpoint of the bend curvature are loaded more heavily on account of the centrifugal force. The result of that is that the telescopic strut units associated with the outer wheels shorten significantly, which leads to lateral tilting of the motor vehicle. The inner wheels are relieved of load, which reduces their road grip and which ultimately can even lead to these wheels lifting off the ground. it is therefore known to transfer a part of the force acting on the outer wheels to the telescopic strut units of the inner wheels by means of a lateral stabilisation device, so that as a whole the lateral tilting of the motor vehicle as it negotiates bends is reduced. Known lateral stabilisation devices work with mechanical, resiliently def ormable force transmission elements, especially with solid torsion bars. If in the case of very fast vehicles, for example racing cars, a high degree of lateral stabilisation is desired, then such mechanical force transmission elements have to be of very solid construction. That implies on the one hand considerable weight, which is undesirable with regard to the driving performance and the fuel consumption of the motor vehicle; on the other hand in many cases the installation space that these solid force transmission elements require is not available.

In one aspect, the present invention provides a device for lateral stabilisation of a motor vehicle, which comprises:

(a) a chassis group; (b) at least one f irst wheel arranged on one side of the chassis group, and a first telescopic strut unit associated with the said first wheel, and at least one second wheel arranged on the opposite side of the chassis group, and a second telescopic strut unit associated with the said second wheel, the first and second wheels being able to perform independent vertical relative movements with respect to the chassis group as a result of changes in length of the respective telescopic struts, (c) means for transferring an excessive load on one of the telescopic strut units at least partially to the respective other of the telescopic strut units, comprising:

(i) a first piston-cylinder unit having a cylinder; a piston, which in the cylinder adjoins at least one first cylinder chamber pressurizable with pressure medium; a piston rod, which is joined to the first telescopic strut unit so that it simultaneously reproduces the changes in length thereof, (ii) a second piston-cylinder unit having a cylinder; a piston, which in the cylinder adjoins at least one first cylinder chamber pressurizable with pressure medium; a piston rod, which is joined to the second telescopic strut unit so that it simultaneously reproduces the changes in length thereof, (d) a reproduction device, which on movement of the piston rod of the one piston-cylinder unit corresponding to a shortening of the corresponding telescopic strut unit, supplies pressure medium to the cylinder chamber of the respective other piston-cylinder unit so that the piston rod of that unit at least partially simultaneously reproduces the movement of the other piston rod.

The present invention provides a device for lateral stabilisation of a motor vehicle, so that with low weight and minimal space requirement it is also possible to achieve a very high degree of lateral stabilisation.

Associated with each telescopic strut unit there is therefore a pistoncylinder unit which on operation effects a loading and hence a shortening of the associated telescopic strut unit, that is, can cause the same sequence of movement that normally takes place on springing of the corresponding wheel. The piston-cylinder units on opposite sides of the motor vehicle are connected to one another by a special arrangement as follows: when the telescopic strut unit on one side the motor vehicle undergoes springing as a result of a corresponding wheel movement, then a cylinder chamber of the piston-cylinder unit on the opposite side is pressurized with pressure medium so that the associated piston rod extends and compresses its associated telescopic strut unit. By this compensating movement the undue lateral tilting of the motor vehicle as is negotiates bends is suppressed in the desired manner. with the design of the lateral stabilisation device according to the invention, the extent of the stabilisation no longer depends on the dimensioning of mechanical components. The device which provides for the cross - connection between opposite sides of the vehicle can be very space-saving and of low weight, as will become clear further below. The piston- cylinder units, which are needed for the device according to the invention, can themselves be accommodated close to the telescopic strut units without problems and have a comparatively low weight.

In a preferred embodiment of the invention, the reproduction device comprises:

a) a second cylinder chamber at each piston-cylinder unit which lies on the side of the piston opposite the first cylinder chamber; b) two pressure medium lines, which connect in a diagonal arrangement the first cylinder chamber of the one pistoncylinder unit to the second cylinder chamber of the respective other piston-cylinder unit.

In this practical form, the "cross -connection" between the piston cylinder units on opposite sides of the motor vehicle is therefore effected exclusively by means of pressure medium lines, preferably hydraulic lines. These have a very small cross-section and can be led from one side of the motor vehicle to the opposite side of the motor vehicle using virtually any relatively small free spaces. The pressure medium system is a closed system and therefore low-maintenance; special auxiliary assemblies, even pumps, are not required.

if a non- compressible pressure medium is used, then in the abovedescribed embodiment of the invention lateral stabilisation would always be 100%. This is not generally desirable. For that reason is it advisable to develop this embodiment of the invention further, so that coupled to each pressure medium line is at least one compensating device which contains a component which is loaded on a first side by pressure medium and is movable against a resilient force acting on a second side. If, therefore, on springing of a wheel as the vehicle negotiates a bend, pressure medium is expelled from a first piston-cylinder unit, its full volume is not introduced into the opposite piston-cylinder unit; on the contrary, part of the displaced volume is taken up by the compensat ng device, the movable component being displaced against the resilient force. By choosing the magnitude of the resilient force it is clearly possible to set the ratio in which the pressure medium displaced from the springing piston-cylinder unit is divided between the compensating device and the opposite piston cylinder unit.

The movable component can be a flexible diaphragm or a displaceable piston.

The design of this construction principle that is most simple is that in which the second side of the movable component adjoins an enclosed volume of gas. If this gas is compressed by movement of the component, the desired resilient counterforce is produced. The magnitude of this counterforce can be determined by the magnitude of the enclosed volume of gas and by the pressure prevailing there. Subsequent alteration of that force is not normally possible, however, once the device has been installed.

An alternative practical form of the compensating device consists in that a spring arrangement acts on the second side of the movable component. Through choice of the spring constant of this spring arrangement, it is possible to influence the extent to which the movable component moves on displacement of pressure medium from the piston-cylinder unit associated with the wheel undergoing springing. This is equivalent to saying that the degree of lateral stabilisation is alterable by that means.

The spring constant of the spring arrangement is preferably adjustable in the installed state. Many possible ways of effecting this are known.

An especially preferred practical form of the spring arrangement with which different effective spring constants can be achieved is one in which the spring arrangement comprises several springs arranged parallel, all of which with one end bear against the movable component and with the opposite end bear against individual respective stop members, each of which can be individually fixed in position or can be released for movement. In this arrangement only those springs of which the associated stop member is fixed in position are effective. By choosing the number and type of the "activated" springs, different effective spring constants of the spring arrangement as a whole can therefore be selected.

The springs arranged parallel can be helical springs arranged coaxially one inside another. This is an especially spacesaving mode of construction.

The stop members can be in the f orm. of movable pistons which on the side lying opposite the relevant spring adjoin an individually pressurizable pressure medium chamber. If the pressure medium chamber adjoining a specific piston lies under pressure, that piston is either not movable at all or movable only by overcoming a force. The corresponding spring is "activated 11 in the above-mentioned sense.

All the above-mentioned exemplary embodiments operate with a device for mutual coupling of the opposite cylinder-piston units which makes use of mechanical operating principles. It is also possible, however, to effect the cross-connection between opposite piston-cylinder units in a purely electrical manner. In a device according to the invention of that kind the reproduction device comprises:

a) a source of pressure medium; b) a pressure medium sump; C) a first position sensor arranged in the vicinity of the first piston- cylinder unit, which detects the relative position of the associated piston rod relative to the corresponding cylinder; d) a second position sensor arranged in the vicinity of the second piston- cylinder unit, which detects the relative position of the associated piston rod relative to the corresponding cylinder; e) a first electrically operable valve associated with the first piston- cylinder unit, by means of which the cylinder chamber of the first piston- cylinder unit is connectable either to the pressure medium source or to the sump; f) a second electrically operable valve associated with the second piston- cylinder unit, by means of which the cylinder chamber of the second piston-cylinder unit is connectable either to the pressure medium source or to the sump; g) an electronic control means which is electrically connected to the two position sensors and to the two valves and is arranged so that by operation of one of the two valves it connects the cylinder chamber of the associated piston-cylinder unit to the pressure medium source and thus effects a movement of the associated piston rod for the purposes of shortening the associated telescopic strut unit when the position sensor associated with the other piston-cylinder unit has determined a movement of the corresponding piston rod for the purposes of shortening the associated telescopic strut unit.

With this "electrical,, variant of the device according to the invention, exclusively electrical leads are required for,,cross -connection" of opposite piston-cylinder units, the space requirement of which leads is minimal. A further advantage of this construction is that the degree of lateral stabilisation can be changed as desired by suitable programming of the electronic control means, which can readily be effected at any time by remote control or by the driver.

The present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a schematic view of a first exemplary embodiment of a device for lateral stabilisation of a motor vehicle with hydraulically operating cross-connection; Figure 2 is a schematic view of a second exemplary embodiment, similar to that of Figure 1; Figure 3 is a schematic view on an enlarged scale of a compensating device for setting the degree of lateral stabilisation, as used in the embodiment shown in Figure 2; Figure 4 is a schematic view of a third exemplary embodiment of a device for lateral stabilisation of a motor vehicle in which the cross- connections are effected electrically.

Referring to the drawings, Figure 1 shows two telescopic strut units 1, 2, which can be, for example, part of the wheel suspension of opposite rear wheels of a racing car. Each telescopic strut unit 1, 2 is connected at one end by means of a joint 3, 4 to the chassis group of the motor vehicle (not shown). The respective opposite end of the telescopic strut units 1, 2 is connected by means of a joint 5, 6 to a respective arm 7a, 8a of a respective V-shaped reversing lever 7, 8 which in its turn is secured to the chassis group by means of joints 9, 10.

A pull rod, which leads to the wheel bearing, is pivotally mounted by way of a respective joint 11, 12 on a respective one of the other arms 7b, 8b of the reversing levers 7, 8. In Figure 1, the pull rods are indicated merely diagrammatically by arrows 13, 14, which point in the extension direction of the pull rods.

-9 The wheel suspension described thus far is known per se.

Articulated at the joints 5, 6 connecting the telescopic strut units 1, 2 with the reversing levers 7, 8 is additionally in each case the end of a piston rod 17, 18, which is part of a double-acting, hydraulic pistoncylinder unit is, 16 respectively. The pistons 19, 20 belonging to these pistoncylinder units 15, 16 and carried by the piston rods 17, 18 divide the inner space of the cylinders 21 and 22 respectively into two opposite cylinder chambers 21a, 21b and 22a, 22b respectively. The cylinder chambers 21a, 22a facing the respective telescopic strut units 1, 2 are referred to hereinafter for the purposes of the description as "inner" cylinder chambers, whilst the opposite cylinder chambers 21b, 22b are referred to hereinafter as ',outer" cylinder chambers.

As can also be understood from Figure 1, the "inner" cylinder chamber 21a of the cylinder 21 belonging to the left-hand telescopic strut unit 1 is connected to the "outer" cylinder chamber 22b of the cylinder 22 belonging to the right-hand telescopic strut unit 2 by way of a first hydraulic line 23. Correspondingly, the "outer" cylinder chamber 21b of the lefthand cylinder 21 is connected to the "inner" cylinder chamber 22a of the right-hand cylinder 22 by way of a further hydraulic line 24. A respective compensating device 25, 26 in the form of a pressure reservoir is connected to the hydraulic lines 23, 24 by way of branch lines 23a, 24b respectively. Each compensating device 25, 26 is divided by a respective diaphragm 27, 28 into two chambers, of which the upper chamber 25a respectively 26a is filled with hydraulic medium, whilst the lower chamber 25b respectively 26b is filled with gas, for example, air.

For the description of the function of the above-explained device for lateral stabilisation of a motor vehicle, let it be assumed that the motor vehicle is negotiating a bend, the wheel belonging to the telescopic strut unit 1 being the outer wheel.

Because of the centrifugal forces, in known manner the outer wheel is loaded more heavily and therefore attempts to spring. This wheel movement is transmitted by way of the pull rod 13 to the reversing lever 7, which pivots clockwise as the wheel springs. Because of the joint connection between the reversing lever 7 and the telescopic strut unit 1, the latter is subjected to pressure, and therefore becomes shorter. At the same time, because of the joint connection (reference number 5) between the reversing lever 7 and the piston rod 17 of the piston-cylinder unit 15 on the left in Figure 1, the associated piston 19 is displaced downwards. On this movement of the piston 19, hydraulic medium is forced out of the inner cylinder chamber 21a of the cylinder 21 on the left in Figure 1 by way of the hydraulic line 23 into the outer cylinder chamber 22b of the cylinder 22 on the right in Figure 1, which is associated with the telescopic strut unit 2 and thus the opposite (inner) wheel. Displacement of hydraulic medium from the inner cylinder chamber 21a of the left-hand piston-cylinder unit 15 into the outer cylinder chamber 22b of the righthand pistoncylinder unit 16 results in the piston 20 of this last pistoncylinder unit 16 likewise being pressed downwards. The righthand telescopic strut unit 2 is consequently also now subjected to pressure and becomes shorter, which by way of the right-hand reversing lever 8 effects a corresponding vertical movement of the wheel associated with the right-hand telescopic strut unit 2.

If the compensating reservoirs 25, 26 were not present and if the hydraulic medium were to be completely non -compressible, the described cross-wise connection of the cylinder chambers 21a, 21b, 22a, 22b of the two piston-cylinder units 15 and 16 would cause a 100-. lateral stabilisation effect, that is, would completely suppress lateral tilting of the motor vehicle. Since this is generally not desirable, the compensating reservoirs 25, 26 are provided. With the filling of air in the chambers 25b, 26b these reservoirs contain a compressible substance. If, therefore, in the described case hydraulic medium is displaced from the inner cylinder chamber 21a of the left-hand piston-cylinder unit 15, then the same volume of hydraulic medium is not introduced into the diagonally opposite cylinder chamber 22b of the right- hand piston-cylinder unit 16. On the contrary, part of the volume which is displaced from the left-hand inner cylinder chamber 21a is injected into the upper chamber 25a of the compensating reservoir 25, with the gas filling in the chamber 25b of that compensating reservoir undergoing compression. By selecting the volume and the pressure of the gas filling in the chamber 25b, it is therefore clear that the degree of lateral stabilisation that is desired in the particular case of application can be set.

If the motor vehicle is negotiating a bend in the opposite direction, the left and the right side in Figure 1 swap their function: now the wheel associated with the right-hand telescopic strut unit 2 becomes the "outer wheel", which attempts to spring as the bend is negotiated. The consequence is that now hydraulic medium is displaced from the inner cylinder chamber 22a of the right-hand piston-cylinder unit 16 by way of the hydraulic line 24 into the outer cylinder chamber 21b of the lefthand piston-cylinder unit 15, a part of the volume of displaced hydraulic medium again passing into the upper chamber 26a of the compensating device 26. As this happens, the gas filling in the lower chamber 26b of that compensating device 26 is correspondingly compressed.

In the exemplary embodiment illustrated in Figure 1 of a device for lateral stabilisation of a motor vehicle, the degree of lateral stabilisation which is determined by the design and type of filling of the compensating devices 25, 26 could not be subsequently changed with ease. Especially in racing, however, it can be important to make the degree of lateral stabilisation adjustable. This becomes possible with the exemplary embodiment that is illustrated diagrammatically in Figure 2. In so far as elements of this second exemplary embodiment correspond to those of Figure 1, they are denoted by the same reference number increased by 100.

In Figure 2, the known elements belonging to the wheel suspension, that is the telescopic strut units and the reversing levers, are no longer illustrated specifically. Appearing again, however, are the double-acting piston-cylinder units 115, 116 with their piston rods 117, 118, the lower ends of which are to be imagined coupled in the same manner as in Figure 1 to the reversing lever and the corresponding telescopic strut unit. The cylinders 121, 122 of the pistoncylinder units 115, 116 are each divided by the associated pistons 119, 120 into an inner cylinder chamber 121a respectively 122a and an outer cylinder chamber 121b respectively 122b. The inner cylinder chamber 121a of the left-hand piston-cylinder unit 115 is connected by way of a hydraulic line 123 to the outer cylinder chamber 122b of the right-hand piston-cylinder unit 116, whilst the outer cylinder chamber 121b of the left-hand piston-cylinder unit 115 is connected in diagonally opposite sequence by way of a hydraulic line 124 to the inner cylinder chamber 122a of the right-hand piston-cylinder unit 116.

Two compensating devices 125, 126, with which the desired degree of lateral stabilisation in each case can be set, are again coupled by way of branch lines 123a, 124a to the two hydraulic lines 123, 124. These compensating devices 125, 126 are of a different construction from the comparatively simple compensating devices 25, 26 of Figure 1, however, and are explained with reference to Figure 3, which illustrates one of these compensating devices 125 on a larger scale.

The compensating device 125 comprises a cup-shaped housing 130, which has on its underside the connection for the branch line 123a. Inside the housing 130, mounted so as to slide, is a piston 127, which assumes the function of the diaphragm 27 of the compensating device 25 of Figure 1. The space below the piston 127 communicates with the hydraulic medium in the hydraulic line 123 and is provided with the reference number 125a, since it is comparable in respect of function with the chamber 25a in Figure 1. Correspondingly, the chamber 125b lying, in relation to the piston 127, opposite the chamber 125a inside the housing 130 is also similar in its function to the chamber 25b of Figure 1. Instead of an air filling, however, this chamber 125b contains a spring device, provided as a whole with the reference number 131 and the spring force of which can be adjusted in the manner described hereinafter.

The spring device 131 comprises two helical springs 132, 133 arranged coaxially one inside the other which in this exemplary embodiment have different spring constants. Both helical springs 132, 133 bear with one end against the side of the piston 127 remote from the chamber 125a.

Supporting of the opposite ends of the two helical springs 132, 133 is effected in a manner to be explained in detail below against a cover 134 which is likewise roughly speaking cupshaped and, with its opening facing downwards, is secured to the housing 130. The cover 134 comprises an inner cylindrical wall 136 starting from its base 135 and coaxial with respect to the outer wall 137. In the annular chamber 138 between the outer wall 137 and the inner cylindrical wall 136 there is arranged, so as to slide axially, an annular piston 139, against which the upper end of the radially outer helical spring 132 bears. The part of the annular chamber 138 enclosed by the piston 139 is pressurized with pressure medium via a first connection 140. In the chamber 141 lying inside the inner cylindrical wall 136 a piston 142 of circular crosssection is axially slidable, against which the radially inner, weaker helical spring 133 bears with its upper end. The chamber 141 is pressurizable with pressure medium by way of a second connection 143 independently of the annular chamber 138.

In the case of the compensating device 125 described above with reference to Figure 3, the degree of lateral stabilisation can be changed as follows by changing the effective spring constants of the spring device 131:

When the pressure medium chambers 138, 141 in the cover 134 are without pressure, the helical springs 132, 133 are relaxed; the piston 127 is the housing 130 can slide upwards virtually without resistance. This means that there is virtually no reciprocal action via the hydraulic lines 123, 124 between the piston-cylinder units 115 and 116, since any displacement of hydraulic medium from an inner cylinder chamber 121a, 122a is completely absorbed by the compensating devices 125, 126.

It is quite different, however, when the pressure medium chambers 138, 141 are put under pressure. If the pressure prevailing there is very high, the adjoining pistons 139 and 142 can be regarded as virtually immobile. Upward displacement of the piston 127 in the housing 130 of the compensating device 125 in Figure 3 can therefore be effected only under compression of both helical springs 132, 133. The spring constants of the spring arrangement 131 is obtained by addition of the spring constants of the separate springs 132, 133.

A further mode of operation of the compensating device 125 would be that in which only the inner pressure medium chamber 141 is pressurized with pressure, whilst the outer pressure medium chamber 138 remains without pressure. On axial displacement of the piston 127 in the housing 130 only the inner, weaker helical spring 133 would then be compressed. In this mode of operation a comparatively weak lateral stabilisation would be achieved.

Finally, in a last mode of operation the inner pressure medium chamber 141 remains without pressure, whilst the outer pressure medium chamber 138 is pressurised with pressure. On axial upward displacement of the piston 127 in the housing 130, the radially outer, stronger pressure spring 132 would have to be compressed. This means that the reciprocal action between the piston-cylinder units 115 and 116 of Figure 2 becomes stronger, which corresponds to greater, yet still not the maximum, lateral stabilisation.

Figure 4 illustrates a third exemplary embodiment of a device for the lateral stabilisation of a motor vehicle, in which the cross -connection between the components associated with the different wheels is effected exclusively electrically. In so far as parts in Figure 4 correspond to those also illustrated in Figure 1, they are denoted by the same reference number increased by 200. Appearing again in Figure 4 are the two telescopic strut units 201, 202, the two reversing levers 207, 208, the two diagrammatically indicated pull rods 213, 214 and two piston- cylinder units 215, 216. The latter are now, however, no longer double- acting but merely single-acting devices having a single cylinder chamber 221b respectively 222b, which lies on the side of the respective piston 219, 220 remote from the associated telescopic strut unit 201, 202. These cylinder chambers 221b, 222b communicate by way of a hydraulic line 234, 235 either with the sump of the hydraulic system or with the pressure medium source (pump) Change-over takes place by means of a respective electromagneticallyoperated change-over valve 244, 245.

Close to the piston rods 217, 218 of the piston-cylinder units 215 respectively 216, there are arranged respective position sensors 246, 247. The position sensors 246 and 247 are arranged so that they are able to detect the relative positions of the piston rods 217, 218 and thus also of the corresponding pistons 219, 220 with respect to the cylinders 221 respectively 222. The position sensors 246, 247 are connected by way of electrical leads 248, 249 to an electronic control means 250. That in turn is connected by way of electrical leads 251, 252 to the electricallyoperated change-over valves 244, 245.

To explain the mode of operation of the exemplary embodiment illustrated diagrammatically in Figure 4, let it again be assumed that the corresponding motor vehicle is negotiating a bend in which the wheel associated with the left-hand telescopic strut unit 201 is the outer wheel, that is, shows a greater tendency to spring. In Figure 4 a state of maximum springing is illustrated.

Normally, the position of the change-over valves 244, 245 is such that the cylinder chambers 221b and 222b are connected to the sump, that is, are substantially without pressure.

In the case of springing of the left-hand wheel already discussed, the piston rod 217 of the left-hand piston-cylinder unit 215 is moveddownwards in a manner similar to that described above for the exemplary embodiment of Figure 1. That movement is detected by the position sensor 246 and reported to the control means 250 by way of the electrical lead 248. If this piston rod movement exceeds a predeterminable value, the electronic control means 250 supplies a signal via the line 252 to the change-over valve 245, which is associated with the right-hand pistoncylinder unit 216. This change-over valve 245 is here displaced into the position illustrated in Figure 4, in which the pressure medium source is connected to the cylinder chamber 222b. The result of this is that the piston 220 of this right-hand piston-cylinder unit 216 is pressed downwards. The movement of this piston 220, or rather of the piston rod 218 connected to it, is detected by the adjacent position sensor 247. When the piston rod 218 has moved downwards by a specific amount, the supply of pressure medium into the cylinder chamber 222b is interrupted. In the exemplary embodiment of Figure 4 the extent of the lateral stabilisation achieved in this manner can be adjusted electrically in a simple manner. Without changing any mechanical components, it can be varied between 0 (virtually no lateral stabilisation) and 10 005 (complete lateral stabilisation) at any time. A further advantage ofthe construction of the device illustrated in Figure 4, is that the elements required for the cross-connection are electrical leads, which take up virtually no room.

Claims

CLAIMS:

1. A device for lateral stabilisation of a motor vehicle, which comprises:

(a) a chassis group; (b) at least one first wheel arranged on one side of the chassis group, and a first telescopic strut unit associated with the said first wheel, and at least one second wheel arranged on the opposite side of the chassis group, and a second telescopic strut unit associated with the said second wheel, the first and second wheels being able to perform independent vertical relative movements with respect to the chassis group as a result of changes in length of the respective telescopic struts, (c) means for transferring an excessive load on one of the telescopic strut units at least partially to the respective other of the telescopic strut units, comprising:

(i) a first piston-cylinder unit having a cylinder; a piston, which in the cylinder adjoins at least one first cylinder chamber pressurizable with pressure medium; a piston rod, which is Joined to the first telescopic strut unit so that it simultaneously reproduces the changes in length thereof, (ii) a second piston-cylinder unit having cylinder; piston, which in the cylinder adjoins at least one first cylinder chamber pressurizable with pressure medium; a piston rod, which is joined to the second telescopic strut unit so that it simultaneously reproduces the changes in length thereof, (d) a reproduction device, which on movement of the piston rod of the one piston-cylinder unit corresponding to a shortening of the corresponding telescopic strut unit, supplies pressure medium to the cylinder chamber of the respective other piston-cylinder unit so that the piston rod of that unit at least partially simultaneously reproduces the movement of the other piston rod.

2. A device according to claim 1, in which the reproduction device comprises:

(a) a second cylinder chamber at each piston-cylinder unit which lies on the side of the piston opposite the first cylinder chamber; (b) two pressure medium lines, which connect in a diagonal arrangement the first cylinder chamber of the one pistoncylinder unit to the second cylinder chamber of the respective other piston-cylinder unit.

3. A device according to claim 2, having at least one compensating device, coupled to each pressure medium line, which contains a component which is loaded on a first side by pressure medium and is movable against a resilient force acting on the second side.

4. A device according to claim 3, in which the movable component is a flexible diaphragm.

5. A device according to claim 3, in which the movable component is a displaceable piston.

A device according to any one of claims 3 to 5, in which the second side of the movable component adjoins an enclosed volume of gas.

7. A device according to any one of claims 3 to 5, having a spring arrangement which acts on the second side of the movable component.

8. A device according to claim 7, in which the spring constant of the spring arrangement is adjustable.

9. A device according to claim 8, in which the spring arrangement comprises several springs arranged parallel, all of which with one end bear against the movable component and with the opposite end bear against individual respective stop members, each of which are individually fixable in position or releasable for movement.

10. A device according to claim 9, in which the springs arranged parallel are helical springs arranged coaxially, one inside another.

11. A device according to claim 9 or claim 10, in which the stop members are in the form of movable pistons which on the side lying opposite the relevant spring adjoin an individually pressurizable pressure medium chamber.

12. A device according to claim 1, in which the reproduction device comprises:

(a) a source of pressure medium; (b) a pressure medium sump; (c) a first position sensor arranged in the vicinity of the first piston-cylinder unit, which detects the relative position of the associated piston rod relative to the corresponding cylinder; (d) a second position sensor arranged in the vicinity of the second piston-cylinder unit, which detects the relative position of the associated piston rod relative to the corresponding cylinder; (e) a first electrically operable valve associated with the first piston- cylinder unit, by means of which the cylinder chamber of the first piston- cylinder unit is connectable either to the pressure medium source or to the sump; (f) a second electrically operable valve associated with the second piston-cylinder unit, by means of which the cylinder chamber of the second piston-cylinder unit is connectable either to the pressure medium source or to the sump; (g) an electronic control means which is electrically connected to the two position sensors and to the two valves and is arranged so that by operation of one of the two valves it connects the cylinder chamber of the associated piston-cylinder unit to the pressure medium source and thus effects a movement of the associated piston rod for the purposes of shortening the associated telescopic strut unit when the position sensor associated with the other piston-cylinder unit has determined a movement of the corresponding piston rod for the purposes of shortening the associated telescopic strut unit.

13. A device for lateral stabilisation of a motor vehicle, substantially as herein described with reference to and as illustrated in any one of Figures 1 to 4.