Valve for hydraulic damper

Abstract

The invention relates to a valve to ensure pressure compensation between subchambers of a hydraulic damper, wherein the valve comprises a first side for connection to a first subchamber and a second side for connection to a second subchamber, the valve is designed to shut off in its rest position a flow of fluid between the two sides and comprises, when deflected from its rest position, a passage channel with a passage cross-section for admitting the flow of fluid, the valve comprises two valve elements guided towards each other and movable towards each other along a path of movement in a movement direction x, one of the two valve elements is designed as a moving element and the other valve element as a seat element, a pressure can be applied to the moving element, on the load side thereof, by a fluid coming from the first side, generating an effective force for moving the moving element in the moving direction x, and the moving element is connected to a spring system which applies to the moving element a spring force, generating a restoring force opposite to the effective moving force. At least one of the valve elements comprises a cylinder section comprising a plurality of passages, the passage channel runs through at least some of the passages and the passage cross-section is limited by a cross-section of these passages, while the other valve element comprises a closed cylindrical surface which lies on the one valve element in the rest position, shutting off the flow of fluid, and the passage cross-section can be adjusted by the deflection of the valve as a result of the movement of the moving element towards the seat element in the direction of movement x, the passage cross-section increasing with the deflection.

Claims

1. A valve configured to ensure equalisation of pressures between sub-chambers of a hydraulic damper, the valve comprising: a first side for connection to a first sub-chamber and a second side for connection to a second sub-chamber, wherein the valve, when in a rest position, is configured to block a flow of fluid between the first side and the second side, and, when displaced from the rest position, is configured to open a through-flow path with a through-flow cross-section to allow the flow of the fluid, wherein the valve comprises two mutually guided valve elements that are movable relative to each other in a direction of movement (x), wherein one of the two valve elements is configured as a moving element and the other valve element is configured as a seat element, wherein the moving element is configured to be exposed on a load side to a fluid pressure on the first side to create an effective displacement force acting on the moving element in the direction of movement (x), wherein the moving element is connected to a spring system to exert a restoring spring force opposing the effective displacement force on the moving element, wherein one of the two valve elements includes a cylinder section with a plurality of passages, wherein the through-flow path passes through at least some of the passages and the cross section of the through-flow path is limited by a cross-section of the passages, wherein the other valve element comprises at least one cylinder shell section that, at least in the rest position, rests against the first valve element to block the flow of the fluid, wherein the cross section of the through-flow path is adjustable via excursion of the valve as a result of displacement of the moving element relative to the seat element in the direction of movement (x), and wherein the cross section of the through-flow path is adjustable such that the cross section of the through-flow path increases as the excursion of the valve increases, wherein, when in the rest position or a position displaced from the rest position, an effective area of the moving element, via which the moving element is to be exposed to a fluid on the first side exerting pressure on the moving element to create the effective displacement force on the moving element is less than a cross-sectional area of the cylinder section containing the passages, wherein the valve has a damping system comprising at least one damping chamber, located between the seat element and the moving element and having a volume dependent on a position of the moving element along the displacement path, wherein the damping system comprises a damping chamber bypass to connect the at least one damping chamber to the first and/or second sub-chamber, wherein the at least one damping chamber communicates with the flow-through path exclusively via the damping chamber bypass, and wherein fluid can only enter and can only exit the at least one damping chamber through the damping chamber bypass.

2. The valve according to claim 1, wherein the valve comprises a bypass for continuous connection of the two sides.

3. The valve according to claim 1, wherein the cylinder section of the valve element with the passages is configured as a hollow cylinder.

4. The valve according to claim 1, wherein at least one section of the other valve element is configured as a hollow cylinder with the at least one cylinder shell section, wherein a further cylinder shell section with passage openings is arranged axially in line with the at least one cylinder shell section.

5. The valve according to claim 1, wherein the at least one cylinder shell section of the other valve element comprises two cylinder shell sections separated from each other in the direction of movement (x) by passage openings, wherein the one valve element has two zones separated from each other in the direction of movement (x), each with passages.

6. The valve according to claim 1, wherein the combined cross-sectional area of the passages through which the through-flow path passes increases with the excursion of the valve from the rest position by the displacement of the moving element along a displacement path.

7. The valve according to claim 1, wherein at least some of the passages are mutually offset with their centres in the direction of movement (x).

8. The valve according to claim 1, wherein the number of passages in the direction of movement (x) varies, wherein the number of passages increases in the direction of movement (x) such that the number of passages included in the through-flow path will increase as the excursion of the valve from the rest position and the associated displacement of the moving element along its displacement path increases.

9. The valve according to claim 7, wherein at least some of the passages mutually offset in the direction of movement (x), have differing cross-sectional areas, wherein the cross-sectional area of passages increases in the direction of movement (x) such that the cross-sectional area of passages included in the through-flow path increases with increasing excursion of the valve from the rest position.

10. The valve according to claim 1, wherein the diameter of the moving element changes at least by section, in a stepped manner and reducing towards the load side in the direction of movement (x).

11. The valve according to claim 1, wherein the moving element has a fluid channel that extends parallel to the direction of movement (x) with at least one component of direction to ensure a hydraulic connection between the load side and a side opposite to the load side of the moving element, wherein a back pressure chamber is arranged at the opposite side configured to take up and retain fluid reaching the opposite side via the hydraulic connection, to create back pressure on the opposite side of the moving element to ensure exertion of a force on the moving element to oppose the displacement force.

12. The valve according to claim 1, wherein the spring system comprises a spring element and a support element connected to the seat element, wherein a tension adjustor is provided to tension the spring element between the support element and the moving element in order to pre-set the restoring force the spring system exerts on the moving element when in rest position.

13. The valve according to claim 1, wherein the moving element and the seat element are each stepped in the direction of movement (x), wherein the damping chamber is created between the steps of the two valve elements.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention is explained in detail below, based on exemplary embodiments of the invention illustrated by means of six Figures. The figures show:

(2) FIG. 1a is a schematic sectional view of a first embodiment of the valve according to the invention;

(3) FIG. 1b is a schematic sectional view of a variation on the first embodiment;

(4) FIG. 2 is a schematic sectional view of a second embodiment of the valve according to the invention;

(5) FIG. 3a is a schematic sectional view of a third embodiment of the valve according to the invention;

(6) FIG. 3b is a schematic sectional view of a section of a variation on the third embodiment of the valve according to the invention;

(7) FIG. 4 is a schematic sectional view of a fourth embodiment of the valve according to the invention;

(8) FIG. 5 is a schematic sectional view of a fifth embodiment of the valve according to the invention; and

(9) FIG. 6 is a schematic sectional view of an embodiment of the hydraulic damper according to the invention.

DETAILED DESCRIPTION

(10) FIG. 1a illustrates an embodiment of valve 1 according to the invention by way of a schematic cross-section. FIG. 1a shows valve 1 in its rest position. Valve 1 comprises a seat element 3 and a moving element 4. Seat element 3 has a cylindrical section in the form of a hollow cylinder with a closed cylindrical shell section 7. This cylindrical section of seat element 3 holds a section of moving element 4, which is also constructed as a hollow cylinder featuring passages 6 in its cylinder shell. The hollow cylinder section of moving element 4 fits loosely into the aforementioned hollow cylinder section of seat element 3. Moving element 4 and seat element 3 are mutually guided over the two sections, whereby the play between moving element 4 and seat element 3 is sufficient to allow small quantities of hydraulic fluid to penetrate between moving element 4 and seat element 3, thereby lubricating between the elements.

(11) FIG. 1a shows that the diameter of moving element 4, which in some embodiments and also in the embodiment shown in FIG. 1a, may be taken as equivalent to the cross-section of moving element 4 orthogonal to the direction of movement, changes in steps. From the step on its load side to its opposite side, the cross-section of moving element 4 actually increases in steps. Since seat element 3 has a matching stepped design, it has an end stop 31 against which moving element 4 will rest when in rest position. The matching stepped design of seat element 3 and moving element 4, creating an end stop 31 against which moving element 4 will come to rest against seat element 3, may have general advantages to valves according to the invention.

(12) In rest position, spring system 5 will press moving element 4 against the end stop of seat elements 3. Spring system 5 comprises spring element 51 and support element 52 and an adjustment device 53. Adjustment device 53 is designed as a thread between support element 52 and seat element 3. This will allow the spring force which spring system 5 will exert on moving element 4 to be set via adjustment device 53. Spring element 51 will always be connected to seat element 3 via support element 52. The restoring force exerted by spring system 5 on moving element 4 in rest position and when deflected from rest position is adjustable via the spring tension.

(13) In rest position as illustrated, passages 6 of moving element 4 will be opposite closed cylinder shell section 7 of seat element 3, with the effect that valve 1 has no through-flow path in this position. The closed cylinder shell section 7 will effectively prevent through-flow from first side 100 to second side 200 through passages 6. Valve 1, however, has a bypass 8 that permanently interconnects sides 100 and 200 of valve 1, allowing a slight difference in pressure that may arise on sides 100 and 200 to be compensated via bypass 8.

(14) When pressure in excess of the pressure in rest position is exerted on valve 1 from its first side 100, moving element 4 will, on its load side facing first side 100, experience a displacement force towards the second side 200.

(15) As soon as the displacement force exceeds the restoring force, valve 1 and thus moving element 4 will be deflected from its rest position, wherein moving element 4 will move in the direction of movement x which, in the illustrated embodiment of the invention, coincides with the axis of the cylinder section designed as a hollow cylinder with passages 6 of the moving element 4 and with the axis of the cylinder section designed as a hollow cylinder with closed cylinder shell section 7 of seat element 3. As soon as moving element 4 is displaced from its rest position to the extent that at least one of the passages 6 in the direction of movement x is positioned adjacent to closed cylinder shell section 7, valve 1 will have a through-flow path running through the relevant passage or passages 6, with its through-flow cross-section restricted by the cross-section of the relevant passages 6 and, depending on the displacement of moving element 4 and possibly also by the closed cylinder shell section 7 which, depending on the excursion of valve 1 from its rest position, may cover part of the cross-section of at least one of the passages 6.

(16) As shown in FIG. 1, valve 1 according to the invention has several passages 6, with different cross-sections and with their centres offset from each other in the direction of movement x. The through-flow cross-section of the through-flow path will therefore change, depending on how far valve 1 and thus moving element 4 are displaced from rest position. The through-flow cross-section of the through-flow path is thereby adjustable via the excursion of valve 1 from rest position.

(17) FIG. 1b schematically illustrates a cross-section of an embodiment of valve 1 according to the invention, analogous to FIG. 1a.

(18) The embodiment shown in FIG. 1b essentially corresponds to the embodiment shown in FIG. 1a wherein, however, the embodiment shown in FIG. 1b has been altered a way to include sealing element 14, a damping chamber 12 and a damping bypass 13. Furthermore, the effective area via which pressure by a fluid on the first side 100 will exert a force on the load side of moving element 4, is different from the embodiment shown in FIG. 1a.

(19) The sealing element 14 is embraced by seat element 3, wherein seat element 3 and sealing element 14 constitute an inherently stable unit. Seat element 3 thereby has a stepped design that matches a correspondingly stepped form created by the stepped design of moving element 4. Damping chamber 12 is located between the steps of moving element 4 and seat element 3. Damping chamber 12 has a hydraulic connection to the first side 100 via damping bypass 13, thus permanently connecting damping chamber 12 with the first sub-chamber when valve 1 is connected to a first sub-chamber on its first side 100. When moving element 4 is displaced from its rest position shown in FIG. 1b, a fluid from the first side 100 will reach damping chamber 12 via damping bypass 13. A displacement of moving element 4 from its rest position is largely prevented unless fluid can reach damping chamber 12. The small damping bypass 13 connecting damping chamber 12 and first side 100 will ensure additional damping of valve 1, which may be beneficial especially when deploying valve 1 in a hydraulic damper according to the invention. It is evident from FIG. 1b that the volume of damping chamber 12 will depend on the position of moving element 4 along the displacement path in the direction of movement x.

(20) FIG. 1b furthermore shows that diameter d2 of the cylinder section of moving element 4 containing passages 6, is significantly greater than diameter d1 which determines the effective area over which moving element 4 will be subjected on its load side to pressure by a fluid on first side 100, thereby to exert a displacement force on moving element 4. As per the embodiment shown in FIG. 1b, valve 1 is correspondingly designed such that the effective displacement force exerted by pressure on first side 100 on moving element 4 may be relatively small for a certain first side 100 pressure on valve 1, whilst the through-flow cross-section through arrangement of passages 6 in a cylinder section with a large diameter d2 may be correspondingly large for a relevant excursion of valve 1 from its rest position.

(21) FIG. 2 schematically shows a further embodiment of valve 1 according to the invention. Valve 1 comprises a seat element 3 with a hollow cylindrical section that contains passages 6 in its cylinder shell. In the rest position of valve 1 shown in FIG. 2, valve 1 has no through-flow path, since it is designed to block the flow of fluid between the two sides 100, 200. In rest position, a closed cylinder shell section 7 containing moving element 4 is to this end positioned opposite passages 6. The closed cylinder shell section 7 is not, however, in close contact with the edge of passages 6 in rest position, since both seat element 3 and moving element 4 are stepped, thereby reducing the diameter along the direction of movement x of moving element 4 from diameter d2 to diameter d3 and correspondingly reducing the inside diameter of the hollow cylindrical seat element 3 from d2 to d3.

(22) Spring system 5 is designed analogous to spring systems 5 of the embodiments shown in FIGS. 1a and 1b and correspondingly features a spring element 51, a support element 52 and an adjustment device 53. Spring system 5 will in rest position press moving element 4 against the ring-shaped end stop 31 which is embraced by seat element 3. When pressure is exerted on moving element 4 from the first side 100 in a way to exert an effective displacement force on moving element 4 that exceeds the restoring force the spring system 5 is exerting on moving element 4, valve 1 and thereby moving element 4 will be displaced from rest position, effectively displacing moving element 4 from rest position in the direction of movement x. As soon as passages 6 are positioned at least partially adjacent to closed cylinder shell section 7 of moving element 4 when moving element 4 is displaced in the direction of movement x, valve 1 will have a through-flow path with a cross-section that will increase as the excursion in the direction of movement x increases, until the closed cylinder shell section 7 fully exposes all the passages 6. In the embodiment of the invention shown in FIG. 2, support element 52 has a bypass 8 via which sides 100 and 200 of valve 1 will be permanently hydraulically connected.

(23) Moving element 4 furthermore comprises a fluid channel 10 connecting the load side of moving element 4 to the opposite side of moving element 4. Seat element 3 comprises a back pressure chamber 11 on the opposite side of moving element 4.

(24) When pressure is brought to bear on valve 1 from its first side 100, fluid will pass through fluid channel 10 to the back pressure chamber 11, to there exert a force against direction of movement x on moving element 4. The effective area via which a fluid on the first side 100 will thus exert pressure on moving element 4 to thereby create a displacement force on moving element 4 in the direction of movement x, may thus be calculated based on the difference of the cross-sections defined by diameters d2 and d3. The displacement force may thus be kept low in this way, even should the first side 100 exert high pressures valve 1, thus allowing the use of simple and low-cost spring systems 5 in valve 1 in the illustrated embodiment according to the invention.

(25) FIG. 3a schematically depicts a variation on the embodiment illustrated in FIG. 2. The embodiment illustrated in FIG. 3a differs from that in FIG. 2 mainly in terms of the moving element 4 exhibiting a cylinder section with passages 6, wherein seat element 3 provides passage openings 9. In the rest position shown in FIG. 3, valve 1 will block the flow of fluid between the two sides 100, 200 of valve 1. Bypass 8 will allow only a small fraction of fluid to flow between the two sides 100, 200. When valve 1 is displaced from rest position, thereby also displacing element 4 away from its rest position against stop 31, a through-flow path will open in valve 1 as soon as the cross-sectional areas of at least some of the passages 6 overlap with the cross-sectional areas of at least some of the passage openings 9. As explained already, the provision of passage openings 9 and passages 6 will allow particularly good adjustment of the passage cross-section as a function of the excursion of valve 1.

(26) The fact that, in the example of the embodiment of the invention shown in FIG. 3a, the centres of passages 6 are offset to each other in the direction of movement x, partially at least, is another factor contributing to the good adjustability of the cross section of the through-flow path. The number of passages 6 whose cross-section may be positioned opposite the cross-section of passage openings 9, is thus variable as a function of the displacement of moving element 4. This also means that the joint cross-sectional area of passages 6 included in the through-flow path may be increased as the excursion from rest position increases.

(27) FIG. 3b shows a section of an example of an embodiment of a valve 1 according to the invention, corresponding to a variation on valve 1 as shown in FIG. 3a. As opposed to the valve 1 shown in FIG. 3a, the valve 1 shown in FIG. 3b has a damping chamber 12 and a further damping chamber 121, each with a hydraulic connection to the first side 100 of valve 1 via a damping bypass 13, 131. Damping chambers 12, 121 are created by means of corresponding steps provided in seat element 3 and moving element 4. FIG. 3b shows that the volume of damping chambers 12, 121 will change as the moving element 4 is displaced in the direction of movement x. Starting from rest position as shown in FIG. 3b, the volume of damping chamber 12 will increase with increasing excursions, whilst the volume of damping chamber 121 will decrease with increasing excursions. Both damping chambers 12, 121 and their assigned damping bypasses 13, 131 will in any case increase the damping in valve 1 shown in FIG. 3b, since bypasses 13, 131 will limit the flow of fluid into and out of damping chambers 12, 121, thereby damping displacements of moving element 4 relative to seat element 3 and the required change in volume of damping chambers 12, 121 and the commensurate flow of fluid through damping bypasses 13, 131.

(28) FIG. 4 shows another example of an embodiment of a valve 1 according to the invention. The example of an embodiment as shown in FIG. 4 also has a moving element 4 and a seat element 3, with also a spring system 5 comprising spring element 51, support element 52 and adjustment device 53. Seat element 4 has a bypass 8 connecting the load side with the opposite side of moving element 4, thereby allowing a small flow of fluid between sides 100, 200 of valve 1 even at very slight pressure difference between sides 100, 200. Moving element 4 has a diameter d1 at its load side, creating an effective area over which fluid at the first side 100 will exert pressure on the load side of moving element 4. Moving element 4 furthermore has a cylinder section designed as a hollow cylinder. This cylinder section also comprises passages 6 in the cylinder shell. This cylinder section has a diameter d2 which is significantly larger than diameter d1 of moving element 4 at its load side. The difference between diameters d1 and d2 of moving element 4 is realised through the stepped design of moving element 4. The stepped design thus allows the force exerted on moving element 4 to be kept relatively low due to the small effective area on the load side, even should the first side 100 exert large pressures on moving element 4, whereas a large cross-section of the through-flow path through passages 6 for a specific excursion of valve 1 may be ensured by providing passages 6 on a cylinder section with a large diameter d2.

(29) In the rest position shown in FIG. 4, spring system 5 presses moving element 4 against end stop 31 of seat element 3. Moving element 4 will be displaced from its rest position when a displacement force acts on the load side of moving element 4 that exceeds the restoring force spring system 5 exerts on moving element 4 against direction of movement x.

(30) As soon as moving element 4 is displaced from its rest position in direction of movement x such that the closed cylinder shell section 7 is positioned next to passages 6, with the cross-section of at least some of the passages 6 overlapping the cross-section of passage openings 9 that are arranged in a cylinder shell section of seat element 3, a through-flow path will open in valve 1, allowing fluid to pass from the first side 100 to the second side 200.

(31) FIG. 4 furthermore shows that moving element 4 includes another cylinder section with more passages 6. Via the excursion of moving element 4 from rest position along its displacement path, the flow of fluid through the through-flow path may, with increasing excursion, be increased by moving additional passages 6 closer to the second side 200, thereby reducing the resistance in the through-flow path. This is because another closed cylinder section of seat element 3 will be positioned opposite the further passages 6, thereby shortening the path a fluid flowing along the further closed cylinder section must take from the first side 100 to reach the second side 200, as moving element 4 moves from its rest position. The further passages 6 will moreover ensure that fluid entering the hollow cylinder section of moving element 4 from the first sub-chamber 100 via passages 6, will be able to exit this section of moving element 4 to enter the second sub-chamber 200 via a large through-flow cross-section, thereby ensuring that the flow of fluid from first sub-chamber 100 to second sub-chamber 200 will be throttled exclusively through the combinations passage openings 9 and passages 6 that regulate fluid inflow from the first sub-chamber 100 to moving element 4.

(32) The valve 1 according to the invention, shown in FIG. 4, furthermore comprises a damping chamber 12 and a damping bypass 13. Valve elements 3, 4 are each stepped, thus exhibiting a shape stepped down in the direction of movement. The space between steps creates the damping chamber 12. The volume of damping chamber 12 thus varies as the position of moving element 4 varies along the displacement path. Damping bypass 13 is constructed as a bore in moving element 4, connecting the second sub-chamber 200 with damping chamber 12. Since damping chamber 12 hydraulically communicates with its environment exclusively via damping bypass 13, a flow of fluid through damping bypass 13 will be required to vary the volume of damping chamber 12. The small cross-section of damping bypass 13 will therefore further enhance the damping performance of valve 1.

(33) FIG. 5 schematically illustrates a further embodiment of valve 1 according to the invention. Valve 1 embraces a seat element 3 and a moving element 4, each stepped in the direction of movement x. The design stepped in the direction of movement x generally refers to one of the valve elements 3, 4 having a first cross-section at a first position, which will then change stepped in the direction of movement x for the valve element to exhibit a second cross-section at a second position. The other valve element, provided it is shaped to match the stepped shape of the first valve element, will exhibit a recess with a cross-section matching the first cross-section of the first valve element, wherein the other valve element, at a further position spaced in the direction of movement x from the first position, will exhibit a recess with a second cross-section corresponding to the second cross-section of the first valve element.

(34) In the present case, seat element 3 comprises a first cylinder section with a cross-section defined by diameter d1 and, offset in the direction of movement x, a second cylinder section with a cross-section defined by diameter d2, wherein diameter d2 is significantly larger than diameter d1. Moving element 4 is designed as a correspondingly hollow cylinder, with a first and a second section with inside diameters essentially matching diameters d1 and d2, thus guiding moving element 4 along seat element 3.

(35) Seat element 3 comprises passages 6 in the second cylinder section. In rest position, passages 6 will be opposite a closed cylinder shell section 7 of the second cylinder section of moving element 4. In rest position as shown in FIG. 5, spring system 5 will press moving element 4 against end stop 31 of seat element 3. With an excursion of valve 1 from its rest position, moving element 4 will be displaced from its rest position in the direction of movement x along the displacement path, allowing passages 6 to be positioned at least partially adjacent to closed cylinder shell section 7 in the direction of movement x. At a specific excursion of valve 1 from its rest position, valve 1 will correspondingly open a through-flow path including at least some of the passages 6.

(36) The stepped designs of seat element 3 and moving element 4 furthermore ensures that passages 6 may be arranged in a cylinder shell section 7 with a large diameter, whereas the effective area over which moving element 4 may experience a first side 100 fluid pressure on its load side is simultaneously kept small, allowing the demands made on spring system 5 in respect of the required restoring force which said system must exert on moving element 4 to adequately damp valve 1 may be kept relatively modest.

(37) The example of an embodiment of valve 1 according to the invention illustrated in FIG. 5 shows a damping chamber 12 with a permanent hydraulic connection to the second side 200 via damping channel 13. Damping chamber 12 is created by the stepped design of seat element 3 and moving element 4. The volume of damping chamber 12 will correspondingly change proportional to the excursion of valve 1 from rest position.

(38) FIG. 6 schematically shows a cross-section of an example of an embodiment of a hydraulic damper 2 according to the invention. Hydraulic damper 2 comprises a working chamber divided by piston 23 into a first sub-chamber 21 and a second sub-chamber 22. Piston 23 is solidly attached to piston rod 24. This means that any displacement of piston rod 24 will result in a corresponding displacement of piston 23 in the working chamber.

(39) The ratio of volumes in the two sub-chambers 21, 22 will change with every displacement of piston 23 along its path in the working chamber. The piston path is the path along which piston 23 is movable in the working chamber in the axial direction of piston rod 24. Piston 23 comprises two valves 1 that will permit a flow of fluid between the two sub-chambers 21, 22 only whilst the difference in sub-chambers 21, 22 pressures exceeds a lower limit. A first valve 1 is designed to allow fluid to flow from the first sub-chamber 21 to the second sub-chamber 22 and will block flow of fluid in the opposite direction; a second valve 1 is designed to allow fluid to flow from the second sub-chamber 22 to the first sub-chamber 21 and to block fluid flow in the opposite direction.

(40) A first mounting device A is connected to the enclosure of the work chamber, whilst a second mounting device B is connected to the piston rod 24. To dampen movement due to forces between the two structural elements, hydraulic damper 2 may be fastened to a first structural element by first mounting device A and to a second structural element by second mounting device B. Forces exerted on the two mounting devices A, B, which compress or expand the hydraulic damper 2, will move piston 23 inside the working chamber. This will compress the fluid inside one of the two sub-chambers 21, 22, creating a difference between the pressures in said sub-chambers and opening at least one of the valves 1 to allow a flow of fluid between sub-chambers 21, 22. Piston 23 will thus effectively move in the working chamber and change the ratio of volumes in the two sub-chambers 21, 22. The movement of piston 23 in the working chamber will dampen the force transmitted to the two mounting devices A, B.

(41) A compensation chamber 25 is located axially in line behind the working chamber. The axial direction is defined by the direction in which piston rod 24 extends. The compensation chamber 25 is connected to the working chamber via a channel 26. Channel 26 has a small cross-section to allow only a small flow of fluid to pass between compensation chamber 25 and the working chamber via this channel 26. Channel 26 connects compensation chamber 25 with the first sub-chamber 21 of the working chamber. A gas pressure chamber 28, separated from compensation chamber 25 by a separation element 27, is located axially in line behind compensation chamber 25.

(42) The separation element 27 is designed axially displaceable, wherein displacement of the separation element 27 will change the ratio of gas pressure chamber 28 the compensation chamber 25 volumes.

(43) In the example of an embodiment shown in FIG. 6, the piston rod 24 will extend along the piston path into compensation chamber 25 for any position of piston 23. Any displacement of piston 23 along the piston path will thus change the piston rod 24 volume in compensation chamber 25. Changing the piston rod 24 volume in compensation chamber 25 will always change the ratio of gas pressure chamber 28 volume and compensation chamber 25 volume (provided hydraulic damper 2 is a closed system without external impact, for instance on gas pressure chamber 28, as is the case here). Displacement of piston 23 in the working chamber in a way to reduce the volume of the first sub-chamber 21 and correspondingly increase the volume of the second sub-chamber 22 will, for instance, directly increase the piston rod 24 volume in compensation chamber 25, thereby moving separation element 27 to decrease the volume of gas pressure chamber 28 and increase the volume of compensation chamber 25. This will increase the pressure in gas pressure chamber 28, creating a restoring force on piston rod 24. A hydraulic damper 2 according to the invention, with its staggered arrangement of working chamber 24, compensation chamber 25 and gas pressure chamber 28, therefore has a very simple design and will at the same time allow a restoring force to be exerted on piston rod 24 and thus piston 23 when the hydraulic damper 2 is displaced from the stationary position in which it was fastened by means of its mounting devices A, B.

(44) Hydraulic damper 2 according to the invention furthermore provides a nozzle 29 via which gas pressure chamber 28 may be filled with gas or its pressure controlled. Excessive overpressure in gas pressure chamber 28 may, for instance, also be effectively prevented in this way. In the example of an embodiment described, simple provisioning of gas pressure chamber 28 via nozzle 29 is facilitated since gas pressure chamber 28 is located axially in line behind compensation chamber 25, which in turn is arranged axially in line behind the working chamber.

(45) The examples of embodiments of the valve according to the invention and of the hydraulic damper according to the invention conclusively demonstrate that the valve according to the invention and the hydraulic damper according to the invention have a simple design and can offer significant advantages over conventional valves or hydraulic dampers. The simple design of the valves according to the invention render these easy and cost-effective to produce, enabling the manufacture of hydraulic dampers to damp forces arising between two structural elements over a large functional range, since the valves can provide a through-flow path of varying cross-section, depending forces exerted on the hydraulic damper, wherein the cross-section of the through-flow path may, for instance, be enlarged for larger forces.

(46) The hydraulic damper according to the invention will therefore be particularly well suited for damping of vibrations over a large functional range.

(47) The staggered design of the hydraulic damper according to the invention will furthermore also facilitate maintenance. The hydraulic damper according to the invention furthermore ensures reliable restoring forces to reduce excursions of structural elements between which the hydraulic damper will be mounted to a minimum and to also dampen vibrations in particular.

LIST OF REFERENCE NUMBERS

(48) 1 Valve 2 Hydraulic damper 3 Seat element 4 Moving element 5 Spring system 6 Passage 7 Closed cylinder shell section 8 Bypass 9 Passage opening 10 Fluid passage 12 121 Damping chamber 131 Damping bypass 14 Sealing element 16 Back pressure chamber 21 First sub-chamber 22 Second sub-chamber 23 Piston 24 Piston rod 25 Compensation chamber 26 Channel 27 Separation element 28 Gas pressure chamber 29 Feed line 31 End stop 51 Spring element 52 Support element 53 Adjustment device 100 First side 200 Second side A First mounting device B Second mounting device d1, d2, d3 Diameter x Direction of movement