TECHNICAL FIELD

The invention relates to a method of setting a position, e.g. a lifting height, and/or springing properties in shock or vibration absorption with the aid of one or more piston-cylinder devices which are subjected to outer forces, absorption or dampening in the respective piston-cylinder device being achieved by a liquid being caused to flow, as a consequence of movement in a piston, between the spaces which are connected by at least one constriction or other flow regulation means, while springing is partially achieved by the liquid being given the opportunity of co-acting with a gas cushion. The invention also relates to a piston-cylinder device for such purposes, the device having adjustable length as well as a springing and dampening function, and includes, a cylinder with a cylinder bore accommodating therein a piston with a piston rod such as to form a cylinder chamber situated on the side of the piston opposite the piston rod, and an annular chamber defined by the exterior of the piston rod and the wall of the cylinder bore.

Such a method and device can be applied or used within all fields where variable lifting height and/or regulatable shock or vibration absorption or dampening is required. The piston-cylinder devices in accordance with the invention can be used, e.g. in applications for vehicles, connected together in different ways with respect to flow for evening out irregularities between such as wheels, tracks or skis. In such cases, or for other apparatus on land or water, they may be included in systems including giros, pumps, levellers or other means for regulating their liquid or air levels. BACKGROUND ART

Not least apparatus known in the field of vehicles or systems of the kind described above for acting on height, springing and shock absorbing or damping are

generally very complicated as a result of properties desired, later on having been added to those of earlier date with the aid of supplementary accessories. DISCLOSURE OF INVENTION The object of the invention is therefore to achieve a method of versatile applicability for setting or regulating level, springing and dampening as well as a simple device for carrying out this method.

The desired result is obtained by the level and the device being given the characterizing features disclosed by the following claims 1 and 2. DESCRIPTION OF FIGURES

Some embodiments of the invention are described in detail in the following and with reference to the accompanying drawings .

Figure 1 schematically illustrates a first embodiment of a piston-cylinder device in accordance with the invention.

Figure 2 schematically illustrates how a piston- cylinder device similar to the one in Figure 1 can be provided with a manual pump means for moving liquid between the spaces mentioned in the introduction.

Figure 3 schematically illustrates a variant of the embodiment according to Figure 1 with a different location for the gas cushion mentioned in the introduction, and provided with a further gas cushion adapted as a recoil or bounce damper.

Figure 4 schematically illustrates a variant of the embodiment according to Figure 3 with both gas cushions situated differently.

Figure 5 schematically illustrates a variation in the arrangement of a gas cushion.

Figures 6 - 10 schematically illustrate examples of applications in vehicles of the method and device in accordance with the invention.

PREFERRED EMBODIMENT

In the following, some embodiments of the device in accordance with the invention are described in detail, and are subsequently taken as the starting point for a description of the method in accordance with the inventio Separate piston-cylinder devices well suited for applying the method in accordance with the invention are illustrated in Figures 1 - 5. Apart from an adjustable length, the piston-cylinder devices have the ability of serving as springs and dampers or shock absorbers. They include a cylinder 1 with a cylinder bore 2 accommodating a piston 3 with a piston rod 4 such as to form a cylinder chamber 5 situated on the opposite side of the piston 3 to the piston rod 4, as well as an annular chamber 6 defined by the piston rod exterior and the cylinder wall in the cylinder bore 2.

A flow system is arranged, which includes a first liquid 7 in two spaces which are connected by a constriction or other flow regulating means 8, e.g. a valve for regulating the flow in response to the pressure conditions and flow direction • . One of these spaces has its size determined in response to the position of the piston 3. This first liquid 7 co-acts with a first gas cushion 9, which comprises an enclosed volume of air or other gas.

The annular chamber 6 is included in the mentioned flow system and constitutes one of the two spaces containing the first liquid 7.

In most of the illustrated embodiments, the first gas cushion 9 is in direct contact with a surface of the first liquid 7.

Figures 1, 2 , 3, 5 and 9 illustrate how the piston rod 4 can advantageously enclose a cavity 10 constituting the second of said both spaces for the first liquid 7. The cavity 10 obtained by reason of the tubular shape of the piston rod communicates with the annular chamber 6

via the flow regulating means 8, which is situated in the region of the piston 3. In Figures 3 and 5 it is shown how the flow regulating means 8 may comprise quite simply of orifices in the tubular wall of the piston rod, these orifices naturally having a predetermined size with respect to the intended damping conditions, while in Figures 1 and 2 it is indicated that the flow regulating means can be of a more complicated kind. Constriction, serving as flow regulating means may also comprise a rather long pipeline with a small bore (Fig. 6 and 7) .

The mentioned first gas cushion 9 can to advantage be placed in the piston rod cavity 10, as illustrated in Figure 3, but as illustrated in Figures 1, 2 and 4, it is also possible to situate it in .the annular chamber 6. It is shown in Figure 8 that the first gas cushion 9 may also be situated outside the cylinder 1 of the piston-cylinder device. More specifically, the annular chamber 6 is connected to a flow system external to the cylinder 1 , this system having a duct which connects the annular chamber 6 with, inter alia, a container 11 for the first liquid 7, this container also serving to contain the second of the spaces mentioned above. A constricted passage in the bottom of the container 7 forms the flow regulating means 8 and the gas cushion 9 is situated at the top of the container.

The cylinder chamber 5 contains a gas, or a gas and a liquid for the formation of a gas cushion on this side of the piston 3 as well. This second gas cushion 12 can also be situated outside the cylinder 1 , as indicated in Figure 9, its co-action with the piston 3 being expedited by a second liquid 13 in a piping system with a container 14 for this gas cushion.

The piston-cylinder device has connections 15 for supply or discharge of the respective medium. The connections can be used for filling a predetermined

amount of the medium, after which they are closed for obtaining a given springing and dampening function or during use of the piston-cylinder device they can be used for varying the amounts of medium in the piston- cylinder device.

It will be seen from Figures 3 and 4 that a third gas cushion 16 can be arranged as recoil or bounce damper in an excess pressure chamber which is resiliently separated from the first gas cushion 9 by a free piston 17 ^" , which is disc-shaped in Figure 3 and annular in Figure 4. An abutment for limiting the stroke of the free piston may be formed and dimensioned to give the free piston a valve function.

In the method in accordance with the invention, a position and/or springing properties for shock or vibration absorption or damping are set with the aid of one or more piston-cylinder devices, which are subjected to external forces. Damping is achieved conventionally in the respective piston-cylinder device, by the first liquid 7 being caused by the movement of the piston 3 to flow between the spaces which are connected via the flow regulating means 8, and springing partially by the liquid 7 being given the opportunity of co-acting with the first gas cushion 9. The piston 3 is acted on by the pressure of the media in the cylinder bore 2 on either side of the piston. One of these media is the first liquid 7, while the other is gas which, either by itself or together with a liquid 13, is enclosed in the cylinder chamber 5 forming the second gas cushion 12 or by the second liquid 13 in the cylinder chamber 5, this liquid being put into communication with an exterior flow system which preferably has an enclosed gas volume forming such a second gas cushion 12. The position of the piston can thus be set by altering the amount of the first liquid 7 by supplying or discharging such liquid, and/or by the

amount of the second liquid 13 or the amount of gas in the second gas cushion 12 being altered by supplying or discharging liquid or gas. The springing properties can be varied by supplying or discharging gas to, or from, the first gas cushion 9 and/or the second gas cushion 12.

Figures 6 - 9 illustrate examples of the use of the method and device in accordance with the invention in some different systems in vehicles. One or more regulating means are provided for acting usually on four piston-cylinder devices of the kind described above. The devices are adapted so that each resiliently connetcts the vehicle chassis to a wheel or other ground contact means, and they are connected to a tilt regulating means 18, which is schematically depicted and may constitute a leveller according to PCT/SE86/00412 or some means with a similar regulating function.

When the vehicle tilts the itfeans 18 with its two pistons causes one of its pistons to exert a sub- pressure on a liquid line 19 and its other piston to exert an excess pressure on another liquid line 19. Each liquid line 19 is connected to the annular chamber 6 in the associated piston-cylinder device such as to affect the tilt of the vehicle via the respective piston 3. The system illustrated in Figure 7 has two tilt regulating means 18, one intended for tilting in the longitudinal direction of the vehicle and the other for its transverse direction. In the same Figure the annular chamber 6 is illustrated partitioned by a free piston 20 in order to afford separate chambers with co-acting effect for the liquid flows from separate means 18.

In Figures 6 and 7 the first gas cushion 9 is to be found in the annular chamber 6 in the respective piston-cylinder device. In Figures 8 and 9 the means 18 is connected in the same way as already described between a pair of pipe-

lines 19. As already mentioned earlier in the description. Figure 8 depicts the first gas chamber 9 as being external to the respective piston-cylinder device. In this Figure the cylinder chambers 5 are moreover mutually connected by a pipeline 21 for common regulation of their content of liquid/gas. Figure 9 depicts the second gas cushion 12 external to the piston-cylinder device, as has already been mentioned earlier in the description, the piston rods 4 having cavities 10 for the first liquid 7 and the first gas cushions 9.

In the systems described connection with Figures 6 - 9, for regulatable springing, tilting regulation can thus be carried out in one or two (Figure 7) directions. The free height over ground of the vehicle can also be set by increasing or decreasing the amount of liquid in the piston-cylinder devices, and the springing properties can be varied by the amount of gas in the piston-cylinder devices. The free height above ground can thus be adjusted with the aid of the amount of liquid to suit the road or ground conditions and the travelling velocity. The springing can be adjusted to load variations with the aid of the amount of gas. Negative steering can be achieved for counteracting centrifugal force when taking bends. The amount of tilt in some detail of the vehicle can be set or be maintained constant It should be noted that the invention can be advantageous¬ ly applied to two-wheeled vehicles also, for varying the springing properties in response to changes in the load, suitably in an embodiment with the described recoil dampening.

Thus, the invention relates to a device intended for use in all areas where variable lifting height, regulatable shock/vibration damping is desired or where merely one property is required.

The device can also be connected to one or more like units in a system crosswise or in parallel for evening out irregularities between wheels, tracks or skis on different types of vehicle on the ground or on rails, surfaces or other apparatus on land or water, connected with a giro, pump, leveller or other apparatus for regulating liquid/air levels.

The chief principle in this device is obtained by the subpressure/vacuum occurring in the enclosed liquid, air, amount of gas. Negative reversed action with suspended inner or outer sleeve. With increasing mass or load due to shocks or pressure the enclosed air/gas amount is distended. A relatively small amount can therefore be used for regulating the required spring- ing function.

Regulation of height: The liquid volume used can be limited in this device to a relatively small volume, and thus a rapid movement can be transmitted between two or more interconnected units. Regulation of springing: To obtain the desired springing, the enclosed air volume/gas volume can be increased or decreased, the previously determined length (height) can be obtained with changed liquid volume. The necessary change in liquid/air/gas volume can be achieved manually with a valve or other pumping means or regulating means. Inertia of the cylinders can also be changed by using a changed viscosity in the liquid. Recoil spring and its regulation: In Figures 2 and 10 springing is obtained in the loading direction of the suspended inner or outer cylinder. A recoil can occur in certain applications when maximum springing is utilised. The recoil spring is applied in this example in the upper part in the form of a loos piston ring with necessary sealing against outer and inner cylinder surfaces. In this example the longitudinal movement of the loose piston ring is limited in one direction by a supporting edge

and in the other by the upper part of the cylinder seal. The width, height and embodiment of the supporting edge in question also fills the function of reduction valve (of the valve constriction type) depending on the desired damping/braking effect. This effect is obtained when the loose piston ring is reached by a higher pressure than the collected effect in the resistance of the reduction edge and the enclosed, predetermined excess pressure. Reduction valve: In the cases where a reduction of the through flow speed of the liquid/air is desirable (regulated, reduced speed depending on pressure) the inner cylinder surface in this example can be provided with several support edges with varying degree of seal against the cylinder wall, with holes or orifices parallel in the longitudinal direction or displaced for obtaining suitably reduced air/liquid speed.

The enclosed space between the cylinder seal and the loose piston ring is subsequently filled with a required regulatable excess pressure. This excess pressure takes up the pressure from the compressed liquid/air volume in the lower part of the cylinder.

The configuration of the device, its outer core, may for several reasons, e.g. strength requirements or other aesthetic reasons, have a configuration, e.g. oval/square or some other suitable shape. Liquid telescope/lift: The device can be used as a telescope/lift. The tunnel of the outer core of a given definite length and diameter is mounted according to the principle in Figure 1. There are a given number of tubes of different diameters fitting into each other with seals according to Figure 1.

The device/the cylindrical tubes are provided with a bottom plus bottom valve. The liquid is sucked out via a pump means placed at the top or in some other place, which sucks out the liquid stored inthe intermediate space which is stored in the lower part of each section.

Figure 2 shows outer cylinder with suspended inner; cylinder provided with pump means with rod/lever and cylinder seals 9 air 8 valves 10 liquid storage space 6 vacuum pressure chamber. Figure 10 shows: (28) attachment of sliding bear¬ ing for shaft. (29) through shaft for guiding inner cylinder. (22) cylinder seal, 30 excess pressure chamber.,, (24) valve/pipe connections for regulating excess pressures and air amount. (26) loose movable cylinder with seal agarifnst inner and outer cylinder. (25) support edge for loose cylinder. Function also as valve (air-liquid brake) . 31 space for liquid/air (vacuum pressure chamber). (24) valve/pipe connection for regulating liquid (22) cylinder seal. Figure 1 has (8, 15) valve/pipe connection/air or liquid, (9) air at cylinder seal (10) liquid/storage space.

The device for areas given comprises two cylindrical objects with two fixed seals, one on the inner cylinder core tube/tubes upper part, one on the lower end of the outer symmetrical tunnel. For regulating the enclosed (7) liquid/ (9) air/gas amounts the cylinder surfaces; are provided with (8, 15) valve or hose/pipe connection for regulating amounts and pressure, provided with one or more support edges on which rests a movable piston (17) with inner and outer seal.

For certain purposes the core of the inner (4) cylinder is used as a reservoir for liquid/air and placing of pump housing provided with regulatable bottom valve. The core of the inner piston/tube can be provided with an end piece with a through shaft for guding some device connected to the vacuum pressure spring.

The lift or spring means has a piston-cylinder device with a cylinder chamber filled with liquid and gas, e.g. air. The device is adapted to increase the volume of the cylinder chamber on taking up load so that the gas volume therein is caused to be thinned out.

The lift or spring means has the cylinder chamber situated between a piston rod preferably formed as a tube, and a cylinder bore in the body of the device. The device is intended for use in the areas stated and others where its properties are considered to be advantageous in comparison with the present art, e.g. variable lifting height, regulatable shock and vibration damping, with small risk of liquid leakage due to vakuum, in loading, high movement speed, small liquid volume, large engagement surface, high springing capacity, adaptability to different loads.

These desires have been solved by utilising the predetermined intermediate space between the inner and outer cylinder diameter. The vacuum or pressure formed when a cylinder seal is fixedly mounted on the inner downward part of the outer cylinder surface and the intermediate space is filled with a predetermined portion of liquid/gas/air, and a fixed seal is mounted on the upper part of the inner cylinder. For regulating liquid levels, valve/pipe connections are mounted on the outer lower cylinder surface and upper inner cylinder core. The inner surface is provided with a support edge/for dampening, and a loose piston with inner and outer seal¬ ing with excess pressure, possibly provided with a regulating valve.

In Figure 6 designation 18 represents a control unit (a mechanical balancing unit comprising pendulum and pistons) . 7 and 9 shows a small area liquid level in a balanced interconnected regulatable system. At 9 is a subpressure chamber with a small regulatable air quantity. A recoil spring 16 comprises a subpressure chamber and a loose piston ring resting on a shoulder.

In Figure 7 is uppermost in both cylinders 1 a regulatable small springing gaz or air quantity. In the same figure is also shown two chambers with regulatable liquid quantities which are acting with respect of two directions, namely a regulating level longitudinally and an other transversely. 18 to left in the same figure is

a device for control transversely and 18 to the right therefrom is a device for control longitudinally.

In Figure 8 as well the designation 18 is a control unit (a mechanical balancing unit comprising pendulum and pistons. The conduits 19 and the two chambers 6 encase liquid quantities 7 regulatable in two directions. Connected thereto are two subpressure chambers 9, each containing a small and regulatable air quantity. The cylinder chambers 5 contain a liquid or air quantity regulatable in two directions.

Also Figure 9 shows a control unit 18 (a mechanical balancing unit comprising pendulum and pistons) . In two directions regulatable liquid quantities 7 are also here enclosed in the conduits 19 and the chambers 6. Subpressure chambers 9 are in this embodiment situated one in each piston rod 4 and contains each a small regulatable air"quantity. In both cylinder chambers 5 is a liquid quantity encased and regulatable in two directions. The cylinder chambers 5 communicate over a conduit. This connecting conduit has a branch conduit with a overpressure chamber 12 having a loose movable piston.

The piston and cylinder device shown in Figure 4 has an air cushion 16 in an overpressure chamber with a loose movable piston 17 resting on a cylinder shoulder. A subpressure chamber is also arranged for a small regulatable air quantity forming the gas cushion 9. Liquid in regulatable quantity is designated 7.

Figure 5 shows a further arrangement with respect to the gas cushion 9 in shape of a small regulatable air quantity in a subpressure chamber. Recoil flow openings are designated 8 and liquid 7 is enclosed in the spaces 6 and 10 in communication with the connection 15.

Figure 3 shows for the gas cushion 16 an over- pressure chamber with a loose movable piston 17 resting

on a cylinder shoulder and immediately there below a subpressure chamber for a gas cushion 9 in shape of a small regulatable air quantity. Liquid 7 in regulatable quantity is enclosed in connection 15 and the spaces 6 and 10. Recoil flow openings are designated 8.