Vibration damper

Abstract

The invention relates to a vibration damper comprising: - an inner tube (10) that is filled or can be filled with a damping medium, - a coaxial outer tube (11) that is fluidically connected to the inner tube (10) by at least one bottom valve (12) and forms an annular gap (13) with the inner tube (10), - a piston unit (14) comprising a piston rod (15) and a piston (16) having a piston valve (17), which forms a first, piston-rod-side working chamber (18) and a second, piston-rod-remote working chamber (19) in the inner tube (10), - a compensation module (20) comprising a compensation chamber (21) for the volume of damping medium displaced by the piston rod (15), a gas chamber (22) that is connected to the compensation chamber (21), and an adjustable damping valve (23) for adjusting the damping effect, and - a bypass device (24) for fluidically connecting the two working chambers (18, 19) via the damping valve (23), wherein the first working chamber (18) is fluidically connectable to the second working chamber (19) by the damping valve (23) in the rebound stage and to the compensation chamber (21) by the damping valve (23) in the compression stage.

Description

[0001] Vibration damper

[0002] Description

[0003] The invention relates to a vibration damper having the features of the preamble of claim 1. Such a vibration damper is known, for example, from DE 10 2018 213 462 A1.

[0004] When tuning vibration dampers, there is a conflict between comfort and driving safety. On the one hand, roadholding of the wheels must be ensured and body movements reduced. This requires greater damping forces. On the other hand, customers expect high driving comfort. This requires a soft tuning. With passive vibration dampers with a single damping force characteristic curve—i.e., the damper's resistance as a function of the compression and rebound speed—the problem is that the tuning is a compromise that covers as many driving situations, road surface excitations, and vehicle loading conditions as possible. The characteristic curve is configured to be either sportier or more comfortable, depending on requirements.

[0005] In semi-active suspensions, this conflict of objectives is resolved by adjusting the damping force via valves in the vibration damper, depending on the situation. The damping force fluctuates between a minimum and maximum characteristic curve. To make semi-active suspension systems accessible to mid-size and compact car segments, optimized vibration dampers are required from a cost perspective.

[0006] In addition, damper length and diameter depend on the available installation space in the vehicle. Installation spaces can vary for different applications. Therefore, damper lengths and diameters are adapted to the individual application. The goal is to use as little installation space as possible for the respective application.

[0007] The vibration damper known from the aforementioned prior art features two controllable solenoid valves for variably adjusting the damping force characteristic curve in the rebound and compression stages. The valve blocks required for this are complex and therefore costly. Furthermore, the installation space required for the known vibration damper is relatively large.

[0008] The invention is based on the object of improving the vibration damper known from the prior art mentioned at the outset in such a way that a variable adjustment of the damping force characteristic curve is achieved with a simplified and as compact as possible design.

[0009] According to the invention, this object is achieved by a vibration damper having the features of claim 1.

[0010] Specifically, this task is solved by a vibration damper with an inner tube that is filled or can be filled with a damping medium and a coaxial outer tube. The outer tube is fluidly connected to the inner tube via at least one bottom valve and forms an annular gap with the inner tube.

[0011] The vibration damper comprises a piston unit comprising a piston rod and a piston with a piston valve. The piston forms a first working chamber on the piston rod side and a second working chamber in the inner tube, remote from the piston rod.

[0012] The vibration damper has a compensation module comprising a compensation chamber for the volume of damping medium displaced by the piston rod and a gas chamber connected to the compensation chamber. The compensation module also has an adjustable damper valve for adjusting the damping effect.

[0013] A bypass device serves to fluidly connect the two working chambers via the damper valve. The invention is characterized in that the first working chamber is fluidly connected to the second working chamber during the rebound stage via the damper valve. Furthermore, the first working chamber is fluidly connected to the compensation chamber during the compression stage via the damper valve.

[0014] The hydraulic circuit according to the invention has the advantage that the adjustability of the damping force characteristic curve can be achieved in both the compression and rebound stages with a single damper valve. The second damper valve required in the prior art can be omitted without compromising the functionality of the vibration damper for a semi-active suspension.

[0015] This is achieved according to the invention in that the first working chamber, i.e. the working chamber on the piston rod side, can be fluidly connected to one and the same damper valve in both the compression and rebound stages if the damping force characteristic curve is to be adjusted.

[0016] The hydraulic circuit is designed so that the first working chamber in the rebound stage can be fluidly connected to the second working chamber via the damper valve. This creates a bypass fluid connection through which a partial flow of the damping medium from the first working chamber is directed through the adjustable damper valve, bypassing the piston valve. By controlling the damper valve accordingly, the damping force characteristic curve in the rebound stage is adjusted.

[0017] The hydraulic circuit is further designed so that the first working chamber is fluidly connected to the compensation chamber via the damper valve, even in the compression stage. Preferably, the second working chamber is fluidly connected to the compensation chamber via the damper valve in the compression stage.

[0018] In contrast to the rebound stage and also to the prior art mentioned above, no direct bypass fluid connection is established between the first and second working chambers in the compression stage. Instead, in the compression stage, the first working chamber is fluidly connected to the compensation chamber via the damper valve if the damping force characteristic curve is to be changed in the compression stage. Since the volume of damping medium discharged from the first working chamber flows through the damper valve, the characteristic curve can also be adjusted in the compression stage. A direct bypass connection between the two working chambers is not necessary in the compression stage. In the compression stage, the first and second working chambers are fluidly connected by a valve, in particular a check valve on the working piston.

[0019] In addition to the reduction in components, the compact design of the compensation module has the advantage that essentially one and the same compensation module can be used for applications in which the compensation module is arranged externally, i.e. outside the outer tube, as well as for applications in which the compensation module is arranged internally, i.e. in the outer tube. This flexibility in use is achieved because, thanks to the hydraulic circuit according to the invention, the damper valve and thus the compensation module can be made comparatively small. In particular, the compensation module can be made so small that it can be accommodated in the outer tube, in particular in the outer tube and the inner tube.

[0020] Preferred embodiments of the invention are the subject of the subclaims.

[0021] This allows the damper valve to be the only adjustable damper valve in the compensation module. The damper is thus significantly simpler in design than previously possible, and correspondingly more cost-effective.

[0022] Preferably, the compensation module is arranged on the outside of the outer tube, in particular parallel to the outer tube. This has the advantage that the vibration damper has a short overall length.

[0023] In a preferred embodiment, the bypass device forms a first fluid connection in the rebound stage between the working chamber, the annular gap, and the damper valve, as well as between the damper valve, the annular gap, the base valve, and the second working chamber. The adjustable damper valve is located in the bypass path and, through appropriate control, effects the desired change in the damping force characteristic curve in the rebound stage. The first working chamber and the annular gap form the inflow side of the damper valve. The annular gap, the base valve, and the second working chamber form the outflow side of the damper valve.

[0024] During the compression stage, the bypass device forms a second fluid connection between the first working chamber, the annular gap, and the damper valve, as well as between the damper valve and the compensation chamber. As in the rebound stage, the damping medium flows from the first working chamber and the annular gap to the damper valve. Unlike in the rebound stage, however, the damping medium does not flow back into the annular gap, but rather into the compensation chamber, which is located on the downstream side of the damper valve. This allows the damping force characteristic to be adjusted by the damper valve during the compression stage as well.

[0025] In a further preferred embodiment, the bypass device has a first connection opening and a second connection opening formed in the outer tube. The first connection opening is fluidly connected to the first working chamber. The second connection opening is fluidly connected to the second working chamber, in particular via the base valve. The damper valve is arranged in the fluid path between the two connection openings, wherein the inlet of the damper valve, i.e. its inflow side, is fluidly connected to the first connection opening. This embodiment is particularly suitable for the external compensation module, which is arranged on the outside of the outer tube. The advantage of this embodiment is that the compensation module is part of the bypass device. The resulting dual function of the compensation module results in a particularly compact design.

[0026] The bypass device preferably has a separating means arranged in the annular gap between the two connection openings. This separating means has the advantage of easily preventing a hydraulic short circuit between the inlet and outlet sides of the damper valve.

[0027] In a further advantageous embodiment, the bypass device has a nozzle in the compensation module that fluidly connects the damper valve and the compensation chamber to separate the inlet flow into the damper valve and the compensation flow into or out of the compensation chamber. A hydraulic short circuit between the inlet side of the damper valve and the outlet side of the damper valve leading to the compensation chamber is thus avoided by a simple design.

[0028] The above-mentioned embodiments are particularly well suited for a vibration damper with an external compensation module arranged on the outer wall of the outer tube.

[0029] In a further preferred embodiment, the compensation module is arranged at least in the outer tube, in particular in the outer tube and the inner tube. This embodiment is a vibration damper with an internal compensation module. This embodiment has the advantage that the vibration damper is particularly slim, which favors certain installation situations.

[0030] In this case, it can be provided that the damper valve is connected at least to the outer tube, in particular to the outer tube and the inner tube, with the gas chamber and / or the compensation chamber being arranged at least partially, in particular entirely, in the inner tube. A compact design of the vibration damper is thus achieved while optimally utilizing the available installation space in the vibration damper.

[0031] Preferably, the bypass device forms a first fluid connection in the rebound stage between the first working chamber, the annular gap, and the damper valve, as well as between the damper valve, the inner tube, the base valve, and the second working chamber. In this simple design, the adjustable damper valve is arranged in the bypass path and is capable of changing the characteristic curve in the rebound stage with the internal compensation module.

[0032] The bypass device can form a second fluid connection in the compression stage between the first working chamber, the annular gap, and the damper valve, as well as between the damper valve and the compensation chamber. This ensures that the adjustable damper valve is arranged in the bypass path for changing the characteristic curve of the compression stage in the internal compensation module. The bypass device preferably comprises the annular gap, into which an inlet opening of the damper valve opens, and at least one passage opening formed in the compensation chamber and opening into the inner tube. The damper valve is arranged in the fluid path between the annular gap and the passage opening. This design of the internally arranged variant of the compensation module is particularly compact, since even fewer components are required than in the variant with an externally arranged compensation module.

[0033] Preferably, in the rebound stage, at least the compensation chamber, the base valve, and the second working chamber are fluidly connected in the direction of flow in this order to compensate for the volume of damping medium displaced by the piston rod. In the compression stage, the aforementioned components are fluidly connected in the reverse order. This embodiment can be combined with both the vibration damper with an external compensation module and the vibration damper with an internal compensation module.

[0034] The fluid connection described above between the compensation chamber, base valve, and second working chamber for compensating the volume of damping medium displaced by the piston rod exists in both the "Hard" and "Soft" or "Comfort" stages. The difference between the "Hard" and "Soft" stages is that in the "Hard" stage, the damper valve is closed and the entire displaced piston rod volume is directed through the base valve or via the fluid connection described above. The annular space volume is directed through the valve in the working piston in a conventional manner. The bypass device is zero in the normal operating range.

[0035] In the "soft" stage, however, a partial flow is passed through the bypass device and thus through the damper valve and a partial flow through the base valve.

[0036] In connection with the hydraulic circuit according to the invention, in which the first working chamber is fluidly connected to the second working chamber via the damper valve during the rebound stage and to the compensation chamber via the damper valve during the compression stage, a flow intersection occurs in which the piston rod volumetric compensation flow intersects with the bypass volumetric flow, both in the compression stage and in the rebound stage. With an external compensation module, the damper valve can be arranged in the fluid path between the compensation chamber and the base valve and can be flowed through. This has the advantage that the damper valve is also used for volume compensation with respect to the piston rod.

[0037] With an internal compensation module, the compensation chamber can be directly fluidically connected to the inner tube. This has the advantage of a simple design.

[0038] The damper valve can be adjustable to adapt to the fluid path of the bypass device so that the damping force characteristic curve can be changed.

[0039] Preferably, the damper valve has an open passage for the volume of damping medium displaced by the piston rod, which passage is fluidly connected to the compensation chamber.

[0040] The invention will be explained in more detail by means of the following exemplary embodiments with reference to the attached schematic drawings.

[0041] Fig. 1 shows the longitudinal section of a vibration damper according to an embodiment of the invention with an externally arranged compensation module;

[0042] Fig. 2 shows the longitudinal section of a vibration damper according to an embodiment of the invention with an internally arranged compensation module;

[0043] Fig. 3 shows the longitudinal section of a compensation module with crimped housing for a vibration damper according to an embodiment of the invention with an externally arranged compensation module;

[0044] Fig. 4 shows the longitudinal section of a compensation module with a welded housing for a vibration damper according to an embodiment of the invention with an externally arranged compensation module; Fig. 5 shows the longitudinal section of a compensation module with an inner sleeve for a vibration damper according to an embodiment of the invention with an externally arranged compensation module;

[0045] Fig. 6 shows the longitudinal section of a compensation module with a membrane for a vibration damper according to an embodiment of the invention with an externally arranged compensation module;

[0046] Fig. 7 shows the longitudinal section of a compensation module with separating piston for a vibration damper according to an embodiment of the invention with an internally arranged compensation module;

[0047] Fig. 8 shows the longitudinal section of a compensation module with gas bag for a vibration damper according to an embodiment of the invention with an internally arranged compensation module;

[0048] Fig. 9 shows the longitudinal section of a compensation module with a membrane for a vibration damper according to an embodiment of the invention with an internally arranged compensation module;

[0049] Fig. 10 shows the vibration damper according to Fig. 1, in which the flow paths in the rebound stage are shown, and

[0050] Fig. 11 shows the vibration damper according to Fig. 1, in which the flow paths in the pressure stage are shown.

[0051] Fig. 1 shows an example of a vibration damper for a motor vehicle, in particular for a motor vehicle with a semi-active chassis. The vibration damper comprises an inner tube 10, which is filled with a damping medium or, in the case of an intermediate product, can be filled with a damping medium. The inner tube 10 is located in an outer tube 11 arranged coaxially with the inner tube 10.

[0052] An annular gap 13 is formed between the inner tube 10 and the outer tube 11. The annular gap 13 extends essentially over the entire length of the inner tube 10. For reasons of clarity, the upper end of the vibration damper is not shown. In the area not shown, a fluid connection is provided between the inner tube 10 and outer tube 11, for example in the form of one or more through-openings, e.g. bores, in the inner tube 10, which open into the annular gap 13. At the other axial end of the vibration damper (the lower end in Fig. 1), a bottom valve 12 is arranged, which forms a further fluid connection between the outer tube 11 and the inner tube 10. The bottom valve 12 is designed in a manner known per se and is therefore not described in more detail.

[0053] The annular gap 13 is directly bounded by the outer wall of the inner tube 10 and the inner wall of the outer tube 11. In other words, the annular gap 13 between the inner tube 10 and the outer tube 11 is free of any tube. This is also generally disclosed in connection with the invention.

[0054] Arranged in the inner tube 10 is a piston unit 14, which has a piston rod 15 and a piston 16 connected to the piston rod 15. The piston 16 is also called the working piston and divides the inner tube 10 into a first working chamber 18 on the piston rod side and a second working chamber 19 remote from the piston rod. In other words, the piston rod 15 is located in the first working chamber 18. The second working chamber 19 is free of a piston rod.

[0055] A piston valve 17 in the piston 16 establishes the fluid connection between the first and second working chambers 18, 19 when the piston 16 is moved axially in the inner tube 10. The damping medium flows through the piston valve 17.

[0056] A compensating module 20 is flanged laterally to the outer tube 11 and extends parallel to the outer tube 11. The longitudinal axes of the outer tube 11 and the compensating module 20 run parallel.

[0057] The compensation module 20 has a compensation chamber 21 and a gas chamber 22 connected to the compensation chamber 21. The compensation chamber 21 and the gas chamber 22 are formed in a housing 25 of the compensation module 20. In the example shown in Fig. 1, the housing 25 is designed as a cylindrical pressure tube or module tube. Other shapes of the housing 25 are possible. The damper valve 23 is fastened in the housing 25. The compensation chamber 21 is located between the gas chamber 22 and the damper valve 23. An axially movable separating piston 42 separates the gas chamber 22 from the compensation chamber 21. When the compensation chamber 21 is filled in the compression stage, the separating piston 42 moves into the gas chamber 22 and compresses the gas located there. In the rebound stage, the separating piston 42 moves in the opposite direction. Other separating elements can be provided instead of the separating piston 42.

[0058] Furthermore, Fig. 1 shows that the damper valve 23, the gas chamber 22, and the compensation chamber 21 form a coherent structural unit. This is also disclosed for all other exemplary embodiments and generally in connection with the invention. The compensation module 20 can therefore be arranged as a unit on or in the vibration damper in a specific application, depending on the available installation space, and is thus flexible in its use.

[0059] The damper valve 23, the gas chamber 22, and the compensation chamber 21 are generally arranged in one and the same housing. The damper valve 23, the gas chamber

[0060] 22 and the compensation chamber 21 are arranged on the same central axis of the housing. The damper valve 23, the gas chamber 22, and the compensation chamber 21 are aligned with one another. This applies to all embodiments and is generally disclosed for the invention. The aligned arrangement of the components of the compensation module 20 has the advantage of a compact design, which is suitable for both a lateral, external, and internal arrangement of the compensation module 20 in the vibration damper.

[0061] The compensation chamber 21 and the gas chamber 22 serve to absorb the volume of damping medium displaced by the piston rod 15 during the compression stage and release it during the rebound stage. The volumes of the compensation chamber 21 and the gas chamber 22 change accordingly during the compression and rebound stages.

[0062] A damper valve 23 is integrated into the compensation module 20 and is used to adapt the damping force characteristic curve to the situation. For this purpose, the damper valve

[0063] 23 is designed to be adjustable. In the example shown in Fig. 1, the damper valve 23 is designed as a controllable solenoid valve. The damper valve 23 has a magnet body 32 connected to a valve body 37 of the damper valve 23. The magnet body 32 and the valve body 37 are arranged coaxially. The valve body 37 and the magnet body 32 are mounted in the housing 25 of the compensation module 20. Other damper valves for adjusting the damping force characteristic curve are possible.

[0064] The vibration damper according to Fig. 1 has a bypass device 24, which serves to create a bypass between the two working chambers 18, 19 past the piston valve 17. The bypass device 24 comprises those components of the vibration damper through which the damping medium flows past the piston valve 17 between the two working chambers 18, 19.

[0065] The damper valve 23 is arranged in the fluid path of the bypass device 24, so that the damping medium passed through the bypass device 24 flows through the damper valve 23. Typically, this is a partial flow of the damping medium that passes through the piston valve 17. The damper valve 23 is therefore part of both the bypass device 24 and the compensation module 20.

[0066] The damper valve 23 is adapted such that, in the rebound stage, when the piston rod 15 is moved out of the inner tube 10, the first working chamber 18 and the second working chamber 19 are fluidly connected through the damper valve 23. In other words, during the rebound stage, damping medium flows from the first working chamber 18 through the damper valve 23, past the piston valve 17, into the second working chamber 19. The damper valve 23 is controlled such that the desired change in the damping force characteristic curve is achieved.

[0067] The damper valve 23 is further adapted such that, in the compression stage, when the piston rod 15 retracts into the inner tube 10, the first working chamber 18 is fluidly connected to the compensation chamber 21 through the damper valve 23. In the exemplary embodiment according to Fig. 1, the connection of the first working chamber 18 to the damper valve 23 is achieved by the bypass device 24 being fluidly connected either to the second working chamber 19 (rebound stage) or to the compensation chamber 21 (compression stage) through the damper valve 23. For this purpose, the bypass device 24 has a first connection opening 26 and a second connection opening 27, each formed in the outer tube 11. Depending on the valve position of the valve body 37, the volume flows from the first working chamber 18 into the equalization chamber 21 (soft stage) or from the second working chamber 19 via the base valve 12 into the equalization chamber 21 (hard stage). Depending on the valve position, both paths are used proportionally.

[0068] The first connection opening 26 is fluidly connected to the first working chamber 18 via the annular gap 13, which is in fluid communication with the inner tube 10 at the upper end of the inner tube 10 (not shown in Fig. 1) through at least one passage opening.

[0069] The second connection opening is fluidly connected to the second working chamber 19 via the bottom valve 12.

[0070] As can be seen in Fig. 1, the damper valve 23 is arranged in the fluid path between the two connection openings 26, 27, with the inflow side or inlet side of the damper valve 23 being fluidly connected to the first connection opening 26. This ensures that the inflow side of the damper valve 23 can be supplied with damping medium from the first working chamber 18 via the annular gap 13 through the first connection opening 26.

[0071] The downstream or outlet side of the damper valve 23 is fluidly connected to the second connection opening 27. These components or this hydraulic circuit enable the bypass function in the rebound stage from the first working chamber 18 to the second working chamber 19 via the damper valve 23, bypassing the piston valve 17 (first fluid connection).

[0072] The downstream side of the damper valve 23 is also fluidically connected to the compensation chamber 21, so that in the pressure stage, damping medium can be guided from the first working chamber 18 into the compensation chamber 21 via the damper valve 23 (second fluid connection).

[0073] The separation of the fluid connections is achieved by the following components.

[0074] The bypass device 24 has a separating means 28 arranged in the annular gap 13 between the two connection openings 26, 27 to separate the inflow and outflow sides of the damper valve 23. In the present example, the separating means 28 is designed as a separating ring with a seal. Other separating means are conceivable.

[0075] In addition, the bypass device 24 has a nozzle 29 arranged in the compensating means 20. The nozzle 29 connects the damper valve 23 and the compensation chamber 21 such that the inlet flow into the damper valve 23 and the flow flowing into or out of the compensation chamber 21 are separated from each other. For this purpose, one axial end of the nozzle 29 is connected to the damper valve 23, and the other axial end of the nozzle 29 is connected to the compensation chamber 21. The nozzle merges into the compensation chamber 21.

[0076] The diameter of the nozzle 29 is smaller on the valve side than on the side of the compensation chamber 21. In other words, the nozzle 29 widens from the damper valve 23 to the compensation chamber 21. The valve-side diameter of the nozzle 29 is adapted such that an inlet opening 38 of the damper valve 23 is located outside the nozzle 29. The passage opening 30 of the damper valve 23 is arranged inside the nozzle 29 for the fluid connection to the compensation chamber 21. The structure of the damper valve 23 is described in more detail below.

[0077] The nozzle 29 causes the damping medium to flow through the first connection opening 26 into the inlet opening 38 of the damper valve 23 without causing a hydraulic short circuit with the flow into or out of the compensation chamber 21. Furthermore, the nozzle forms an axial stop for the separating piston 42.

[0078] In this case, the nozzle 29 has two discrete diameter ranges. Other shapes of the nozzle 29 are possible.

[0079] The damper valve 23 is constructed as follows.

[0080] The damper valve 23 has a (second) annular gap 39, which is fluidly connected to the second connection opening 27. In the rebound stage, the annular gap 39 forms the downstream side of the damper valve 23. In the compression stage, the annular gap 39 forms a further inflow opening of the damper valve 23 in addition to the inflow opening 38, which is fluidly connected to the first connection opening 26.

[0081] A valve mechanism 40 of the damper valve 23 is arranged between the inlet opening 38 and the annular gap 39, by which the volume flow through the damper valve 23 can be varied. For this purpose, the valve mechanism 40 is controlled by the magnetic body 32. The valve mechanism 40 comprises a valve plate arrangement that opens in the inlet direction starting from the first connection opening 26 and closes in the opposite direction. The valve plates are uncontrolled. The valve mechanism 40 further comprises a controlled adjusting element (not shown) that interacts with the magnetic body 32 and varies the volume flow through the damper valve 23.

[0082] An example of the construction principle of such an adjusting device is shown in EP1538366B1, Fig. 1, which is attributed to the applicant, and is therefore not described in more detail.

[0083] Other valve mechanisms or damper valves are possible.

[0084] For fluid communication with the compensation chamber 21, an open passage 31 of the damper valve 23 is provided, which opens into the compensation chamber 21 through the above-mentioned passage opening 30. The open passage 31 is adjustable. It opens into the annular gap 39 of the damper valve 23, thus establishing a fluid connection between the annular gap 39 and the passage opening 30 or the compensation chamber 21. Furthermore, the passage 31 is fluidly connected to the inlet opening 38 of the damper valve 23. The passage 31 designates the passage or channel that extends through the damper valve 23. The passage opening 30 designates the end, i.e., the passage surface, of the passage 31 that opens into the compensation chamber 21.

[0085] The operation of the damper valve 23 is described in more detail below with reference to Figures 10 and 11 and the flow paths shown therein. In the rebound stage according to Fig. 10, the annular space volume flow QR ing of the first working chamber 18 minus a bypass volume flow Q Bypass the piston valve 17 and enters the second working chamber 19, as shown by the arrow through the piston 16.

[0086] The bypass volume flow Q B y P ass flows from the first working chamber 18 through the fluid connection (not shown) between the inner tube 10 and the outer tube 18 into the annular gap 13 and from there through the first connection opening 26 into the damper valve 23. The bypass volume flow Q ByP ass flows through the inlet opening 38 and the valve mechanism 40, ie the spring disk structure and the adjusting element (not shown), and from there into the annular gap 39 of the damper valve 23. From there, the bypass volume flow Q Bypa ss through the second connection opening 27 into the lower part of the annular gap 13 and from there through the bottom valve 12 into the second working chamber 19.

[0087] When the bypass volume flow QBypa ss through the damper valve 23, the damping force characteristic of the vibration damper is adjusted by the valve mechanism 40 depending on the situation.

[0088] The damper valve 23 also has the function of guiding the piston rod volume flow Q piston rod, i.e. the volume flow displaced by the piston rod 15. For this purpose, the piston rod volume flow Q piston rod flows from the compensation chamber 21 through the open passage 31 into the annular gap 39 of the damper valve 23. There, the piston rod volume flow Q piston rod is added to the bypass volume flow Q BypaS s and flows together through the second connection opening 27 into the lower annular gap 13 and from there through the bottom valve 12 into the second working chamber 19.

[0089] This hydraulic circuit, in which the two volume flows Q piston rod and Q B y pass can be described as flow crossing because the volume flows intersect and add up in the (second) annular gap 39. The flow crossing is caused by the valve body 37.

[0090] In the pressure stage, the annular volume flow Q Ring flows through the piston valve

[0091] 17 from the second working chamber 19 into the first working chamber 18. In addition, the bypass volume flow Q B y P from the second working chamber 19 through the piston valve 17 into the first working chamber 18, since, as in the rebound stage, the bypass volume flow Q Bypass flows out of the first working chamber 18 through the fluid connection (not shown) between the inner tube 10 and the outer tube 18. The bypass volume flow Q ByP ass flows through the annular gap 13 and the first connection opening 26 into the damper valve 23. The bypass volume flow Q B y Pass the valve mechanism 40 and enters the annular gap 39 of the damper valve 23. There, the bypass volume flow Q Bypass is added to the volume flow coming from the second working chamber 19 to form the piston rod volume flow Q Piston rod, which flows through the open passage 31 into the compensation chamber 21.

[0092] In the pressure stage, the hydraulic circuit in which the two volume flows add up as described above can also be described as flow crossing because the volume flows cross and add up in the (second) annular gap 39.

[0093] The principle of flow crossing is explained generally in connection with the invention and specifically in connection with the embodiments according to Fig.

[0094] 1 and 2. This applies to both the rebound and compression stages. The design principle and operation of a damper valve for a flow crossing are shown, for example, in the aforementioned EP1538366B1, Fig. 1.

[0095] From the second working chamber 19 flows the piston rod volume flow Q piston rod minus the bypass volume flow Q ByP ass through the bottom valve 12 and the lower part of the annular gap 13 through the second connection opening 27 into the annular gap 39 of the damper valve 23.

[0096] At maximum damping effect, the damper valve 23 is closed. In the rebound stage, the entire annular space volume flow Q Rin g the piston valve 17. In the pressure stage, the piston rod volume Q piston rod is transported through the bottom valve 12.

[0097] At maximum soft damping effect, the damper valve 23 is opened so that the bypass volume flow Q ByPass the annular space volume flow Q Rin g. This directs the maximum damping medium flow rate through the damper valve 23 and the base valve 17. At the maximum soft characteristic in the compression stage, the entire piston rod volume Q piston rod is conveyed through the damper valve 23 into the compensation chamber 21.

[0098] The embodiment shown in Fig. 2 differs from the embodiment shown in Fig. 1 in the installation position of the compensation module 20. The hydraulic circuit principle is the same. Therefore, reference is made to the explanations in connection with Figs. 10 and 11, which are also disclosed in connection with the embodiment shown in Fig. 2, taking into account the modified installation situation of the compensation module 20.

[0099] The reference numerals of the corresponding components in both embodiments are the same. The differences between the two embodiments are described in more detail below.

[0100] As shown in Fig. 2, the compensation module 20 is arranged partially in the outer tube 11 and partially in the inner tube 10. Theoretically, it is also conceivable to arrange the compensation module 20 completely or at least predominantly in the outer tube 11.

[0101] The compensation module 20 is arranged at the axial end of the inner tube 10 and mechanically connects the inner tube 10 and the outer tube 11. The damper valve 23, in particular the valve body 37, is connected on one side to the outer tube 11 and on the other side to the inner tube 10. Specifically, a first section of the valve body 37, which contains the valve components, such as the valve mechanism 40, is seated in a fluid-tight manner in the outer tube 11. A second section of the valve body 37 forms a flange 43, which is fluid-tightly connected to the inner tube 10.

[0102] The damper valve 23 holds the inner tube 10 coaxially in the outer tube 11.

[0103] The magnet body 32 is also firmly connected to the outer tube 11.

[0104] The bottom valve 12 is arranged between the compensation module 20 and the piston 16 and fluidly connects the second working chamber 19 of the inner tube 10 with the receiving section 44 of the inner tube 10, which contains the compensation module 20.

[0105] As further shown in Fig. 2, the gas chamber 22 and the compensation chamber 21 of the compensation module 20 are completely accommodated in the inner tube 10. For this purpose, the shape of the gas chamber 22 and the compensation chamber 21 or the housing 25 is adapted so that they are arranged coaxially in the inner tube 10, forming a (third) annular gap 41. The width of the third annular gap 41 is smaller than the width of the first annular gap 13.

[0106] In addition to the mechanical connection, the compensation module 20, specifically the damper valve 23, establishes a fluid connection between the inner tube 10 and the outer tube 11.

[0107] In the embodiment shown in Fig. 2, the bypass device 24 forms a first fluid connection in the rebound stage between the working chamber 18, the (first) annular gap 13, between the inner tube 10 and the outer tube 11, and the damper valve 23 (inflow side). The first fluid connection further comprises the damper valve 23, the compensation chamber 21, the inner tube 10, specifically the (third) annular gap 41 between the inner tube 10 and the compensation module 20, the base valve 12, and the second working chamber 19 (outflow side).

[0108] In the pressure stage, the bypass device 24 forms a second fluid connection between the first working chamber 18, the (first) annular gap 13 and the damper valve 23 on the one hand (inflow side) and between the damper valve 23 and the compensation chamber 21 on the other hand (outflow side).

[0109] Specifically, the bypass device 24 comprises the (first) annular gap 13 and the inlet opening 38 of the damper valve 23, which in the embodiment according to Fig.

[0110] 2 opens directly into the annular gap 13. In addition, the bypass device 24 comprises at least one (second) passage opening 45, in particular a plurality of (second) passage openings 45, which are formed in the compensation chamber 21, specifically in the housing 25 of the compensation module 20. The (second) passage opening 45 opens into the inner tube 10 and establishes a fluid connection between the compensation chamber 21 and the lower section of the inner tube 10, in which the compensation module 20 is arranged. The passage opening 45 opens into the (third) annular gap 41. The damper valve 23 is arranged in the fluid path between the (first) annular gap 13 and the at least one passage opening 45.

[0111] At least one axial stop 46 is formed in the compensation chamber 21 for the axially movable separating piston 42 arranged in the housing 25. The axial stop 46 is arranged above the (second) passage openings 45.

[0112] This ensures that the (second) passage opening 45 is kept clear and not covered by the separating piston 42, so that the compensation chamber 21 can be filled even when the separating piston 42 is arranged at the bottom. The designations "top / bottom" are to be understood with reference to the illustration in Fig. 2. If the vibration damper is installed in a different position, the designations "top / bottom" are reversed.

[0113] For the structure of the damper valve 23, reference is made to the explanations in connection with the embodiment according to Fig. 1.

[0114] During the rebound stage, the compensation chamber 21, the base valve 12, and the second working chamber 19 are fluidly connected in the flow direction in this order to compensate for the volume of damping medium displaced by the piston rod 15. The piston rod volume flow Q piston rod and the bypass volume flow Q bypass flowing from the (first) annular gap 13 into the compensation chamber 21 are added together. For the flow paths, please refer to the further explanations for Fig. 10.

[0115] In the pressure stage, the above-mentioned components are fluidly connected in reverse order. The bypass volume flow Q B y P ass from the (first) annular gap 13 and the piston rod volume flow Q piston rod minus the bypass volume flow Q ByPass from the (third) annular gap 41 through the (first) through-openings 45 into the compensation chamber 21, so that the compensation chamber 21 is filled with the volume of damping medium displaced by the piston rod 15. For further details, reference is made to the explanations for Fig. 11, which shows the hydraulic circuit principle transferable to the embodiment according to Fig. 2 in conjunction with an externally arranged compensation module 20. In comparison of the two embodiments according to Fig. 1, Fig. 2, in the embodiment according to Fig. 1, the damper valve 23 is arranged in the fluid path between the compensation chamber 21 and the base valve 12. In contrast, in the embodiment according to Fig. 2, the compensation chamber 21 is directly fluidically connected to the inner tube 10, namely through the (second) through-openings 45.

[0116] In both embodiments according to Fig. 1, Fig. 2, no central pipe is required between the inner and outer pipes 10, 11. System pressure prevails between the outer pipe 11 and the inner pipe 10. Since the central pipe is omitted, a comparatively large piston diameter is possible with the same outer pipe dimensions. The externally arranged compensation module 20 can be positioned variably in relation to the outer pipe 10, since the compensation module 20 is not dependent on the position and length of the central pipe and its chimney. The internally arranged compensation module 20 can be positioned variably, since the position and size of the gas space inside the damper (within the outer pipe) do not have to be taken into account. The external compensation module 20 can be installed in any position, e.g. upside down, at any angle to the pipe axis with a modified module flange and / or flow crossing.

[0117] An upside-down installation is possible in both embodiments. In both embodiments, only one magnet is required for the rebound and compression stages. A comparatively large separating piston diameter is possible in the compensation module 20 with the same outer tube dimensions, since the compensation module 20 can be designed essentially independently of the damper tube. Furthermore, a comparatively large piston rod diameter is possible due to the larger separating piston diameter, since a larger separating piston exhibits less wear.

[0118] Below, various exemplary embodiments of the compensation module 20 are explained with reference to Figures 3 to 9. These are suitable for the externally arranged variant (Figures 3 to 6) and for the internally arranged variant (Figures 7 to 9). The basic structure of the compensation module 20 is described in more detail in connection with the exemplary embodiment according to Figure 1, which also applies to the exemplary embodiments of the compensation module 20 according to Figures 3 to 9 and is disclosed in connection with these figures. The special features and differences of the exemplary embodiments of the compensation module 20 are explained below.

[0119] Fig. 3 shows an embodiment of the compensation module 20 in which the housing 25 of the compensation module 20 is connected to the damper valve 23, in particular to the nozzle 29, by a bead 47. An additional sealing element, e.g., an O-ring, is required to seal the nozzle 29 from the housing 25. First, the separating piston 42 with gas filling is inserted, and then the housing 25 is sealed. Contamination from a welding process is avoided. The assembly preload force is effectively transmitted.

[0120] Fig. 4 shows the embodiment of the compensation module 20 according to Fig. 1 without the outer tube 11. The housing 25 is welded to the damper valve 23. This embodiment is suitable for high loads and transmits the assembly preload force well. Furthermore, simple and quick assembly is possible. The seal is achieved via the welded connection between the nozzle 29 and the housing 25. Accordingly, a small number of sealing elements are required. The running surface of the separating piston 42 is only slightly affected.

[0121] Fig. 5 is an embodiment in which the nozzle 29 merges into a sleeve 48 or is formed integrally with it, which rests on the inside of the housing 25. Other connections between the sleeve 48 and the nozzle 29 are possible. The shape of the sleeve 48 corresponds to the inside shape of the housing 25. The sleeve 48 is sealed against the housing 25 in the area of ​​the nozzle 29. This embodiment has the advantage that no additional processes such as beading or welding are required during assembly. Clamping takes place via the sleeve 48. The sleeve can be made of plastic, metal, in a hybrid construction or as a CFRP component. The friction partners (separating piston 42 vs. sleeve 48) can be optimized for one another, e.g. by a PTFE coating of the running surface.

[0122] Fig. 6 shows an embodiment of the compensation module 20 in which the separating piston 42 is replaced by a diaphragm 33 that is stationary in the housing 25. The volume change of the gas chamber 22 occurs through a corresponding expansion of the diaphragm 33 in the gas chamber 22. The diaphragm 33 is fastened in a ring 49 that has an opening for the diaphragm 33. The ring 49 is fastened, e.g. welded, in the housing 25. Other fastening options, such as a beaded connection in combination with an additional sealing element, are possible. The ring 49 is connected to the nozzle 29 in a fluid-tight manner. As can be seen in Fig. 6, the nozzle 29 is designed as a cylinder with a constant diameter. The diameter is adjusted so that the inlet opening 38 of the damper valve 23 is located outside the nozzle 29 and the (first) passage opening 30 is located inside the nozzle 29.This embodiment has the advantage that no friction occurs in the system. The diameter of the diaphragm 33 can be designed smaller than a comparable separating piston, since the diaphragm 33 allows for a larger stroke.

[0123] Fig. 7 shows an embodiment of the compensation module 20, which is installed internally in the vibration damper according to Fig. 2. For the structure and operation of the compensation module 20, reference is made to the explanations for Fig. 2.

[0124] In summary, the compensation module 20 has an internally arranged separating piston 42, which is guided in an additional tube, namely the housing 25, with respect to the inner tube 10. The running surface and the friction partners can be tribologically optimized to reduce separating piston friction. Upside-down installation is possible. To fix the compensation module 20 in the vibration damper, it can be connected either to the base valve 12 or, as shown in Fig. 7, to the damper valve 23. Form-fitting or material-locking connections, such as welding, soldering, gluing, or grouting, are possible.

[0125] Fig. 8 shows an alternative embodiment of the compensation module 20, in which the gas chamber 22 is arranged, in particular clamped, between the base valve 12 and the damper valve 23. For this purpose, a gas bag 34 is provided, which is arranged in a frame 35. The frame 35 is clamped between the base valve 12 and the damper valve 23 and is thus fixed. The compensation chamber 21 is located between the gas bag 34 and the damper valve 23. This embodiment has the advantage that there is no friction between the separating pistons. Furthermore, greater volume compensation is possible than with a separating piston, so that larger piston rod diameters can be realized.

[0126] Fig. 9 shows an embodiment in which the gas chamber 22 is separated from the compensation chamber 21 by a membrane 33. This embodiment differs from the previously explained embodiments for the internally arranged compensation module 20 in that the arrangement of the gas chamber 22 and the compensation chamber 21 is reversed. Specifically, the compensation chamber 21 is arranged between the base valve 12 and the gas chamber 22.

[0127] Furthermore, the housing 25 is not connected to the damper valve 23, as in the embodiments according to Figures 7 and 8, but to the bottom valve 12. In the embodiment according to Figure 9, the (third) annular gap 41 between the housing 25 and the inner tube 10 extends from the bottom valve 12 to the damper valve 23, where it opens into a gap between the damper valve 23 and the end face of the housing 25. In the embodiments according to Figures 7 and 8, the situation is reversed. There, the gap is located between the end face of the housing 25 and the bottom valve 12.

[0128] The at least one, in particular several passage openings 45 for the fluid connection between the compensation chamber 21 and the inner tube 10 are provided in the housing 25 close to the bottom valve 12.

[0129] The operation of the compensation module 20 corresponds to the hydraulic circuit principle explained above. This is described and disclosed in connection with Fig. 9.

[0130] In summary, the embodiment according to Fig. 9 has an internal diaphragm 33, which is accommodated in an additional tube (relative to the inner tube 10), namely in the housing 25. Here, too, separating piston friction is avoided. Furthermore, greater volume compensation is possible than with the separating piston, so that larger piston rod diameters can be realized. Upside-down installation is possible. A diaphragm holder 36 is firmly connected, in particular by a material fit, to the housing 25. The embodiment according to Fig. 9 shows that the compensation module 20 can be connected either to the damper valve 23 or to the base valve 12. Here, too, various types of connection are possible, such as welding, soldering, gluing, beading or other types of connection.

[0131] List of reference symbols

[0132] 10 inner tube

[0133] 11 Outer tube

[0134] 12 bottom valve

[0135] 13 (first) annular gap

[0136] 14 Piston unit

[0137] 15 Piston rod

[0138] 16 pistons

[0139] 17 Piston valve

[0140] 18 (first) workroom

[0141] 19 (second) workroom

[0142] 20 compensation module

[0143] 21 Compensation room

[0144] 22 Gas room

[0145] 23 Damper valve

[0146] 24 Bypass device

[0147] 25 Housing of the compensation module

[0148] 26 (first) connection opening

[0149] 27 (second) connection opening

[0150] 28 release agents

[0151] 29 nozzles

[0152] 30 (first) passage opening

[0153] 31 open passage

[0154] 32 magnetic bodies

[0155] 33 Membran

[0156] 34 Gasbag

[0157] 35 frames

[0158] 36 Membrane holder

[0159] 37 valve body

[0160] 38 Inlet opening of the damper valve 39 (second) annular gap

[0161] 40 Valve mechanism

[0162] 41 (third) annular gap

[0163] 42 separating pistons

[0164] 43 Valve body flange

[0165] 44 Inner tube receiving section

[0166] 45 (second) passage opening

[0167] 46 stop

[0168] 47 bead

[0169] 48 sleeve

Claims

Claims 1. Vibration damper with - an inner tube (10) which is filled or can be filled with a damping medium, - a coaxial outer tube (11) which is fluidly connected to the inner tube (10) by at least one bottom valve (12) and forms an annular gap (13) with the inner tube (10), - a piston unit (14) comprising a piston rod (15) and a piston (16) with a piston valve (17) which forms a first working chamber (18) on the piston rod side and a second working chamber (19) remote from the piston rod in the inner tube (10), - a compensation module (20) comprising a compensation chamber (21) for the volume of damping medium displaced by the piston rod (15), a gas chamber (22) connected to the compensation chamber (21), and an adjustable damper valve (23) for adjusting the damping effect, and - a bypass device (24) for fluidly connecting the two working chambers (18, 19) via the damper valve (23), characterized in that the first working chamber (18) is fluidly connectable to the second working chamber (19) in the rebound stage by the damper valve (23) and to the compensation chamber (21) in the compression stage by the damper valve (23), wherein in the compression stage the second working chamber (19) is fluidly connected to the compensation chamber (21) via the damper valve (23).

2. Vibration damper according to claim 1, characterized in that the damper valve (23) is the only adjustable damper valve in the compensation module (20).

3. Vibration damper according to claim 1 or 2, characterized in that the compensation module (20) is arranged on the outside of the outer tube (11), in particular parallel to the outer tube (11).

4. Vibration damper according to claim 3, characterized in that the bypass device (24) forms a first fluid connection between the first working chamber (18), the annular gap (13) and the damper valve (23) and between the damper valve (23), the annular gap (13), the base valve (12) and the second working chamber (19) in the rebound stage.

5. Vibration damper according to claim 3 or 4, characterized in that the bypass device (24) forms a second fluid connection between the first working chamber (18), the annular gap (13) and the damper valve (23) and between the damper valve (23) and the compensation chamber (21) in the pressure stage.

6. Vibration damper according to one of claims 3 to 5, characterized in that the bypass device (24) has a first connection opening (26) and a second connection opening (27) which are formed in the outer tube (11), wherein the first connection opening (26) is connected to the first working space (18) and the second connection opening (27) with the second working chamber (19), in particular by the base valve (12), wherein the damper valve (23) is arranged in the fluid path between the two connection openings (26, 27) and the inlet of the damper valve (23) is fluidly connected to the first connection opening (26).

7. Vibration damper according to claim 6, characterized in that the bypass device (24) has a separating means (28) which is arranged in the annular gap (13) between the two connection openings (26, 27).

8. Vibration damper according to one of claims 3 to 7, characterized in that the bypass device (24) has a nozzle (29) in the compensation module (20) which fluidly connects the damper valve (23) and the compensation chamber (21) for separating the inlet flow into the damper valve (23) and the compensation flow into or out of the compensation chamber (21).

9. Vibration damper according to claim 1 or 2, characterized in that the compensation module (20) is arranged at least in the outer tube (11), in particular in the outer tube (11) and in the inner tube (10).

10. Vibration damper according to claim 9, characterized in that the damper valve (23) is connected at least to the outer tube (11), in particular to the outer tube (11) and the inner tube (10), wherein the gas space (22) and / or the compensation space (21) are arranged at least partially, in particular completely, in the inner tube (10).

11. Vibration damper according to claim 9 or 10, characterized in that the bypass device (24) forms a first fluid connection in the rebound stage between the first working chamber (18), the annular gap (13) and the damper valve (23) and between the damper valve (23), the compensation chamber (21), the inner tube (10), the base valve (12) and the second working chamber (19).

12. Vibration damper according to one of claims 9 to 11, characterized in that the bypass device (24) forms a second fluid connection between the first working chamber (18), the annular gap (13) and the damper valve (23) and between the damper valve (23) and the compensation chamber (21) in the pressure stage.

13. Vibration damper according to one of claims 9 to 12, characterized in that the bypass device (24) comprises the annular gap (13), into which an inlet opening (38) of the damper valve (23) opens, and at least one passage opening (45) which is formed in the compensation chamber (21) and opens into the inner tube (10), the damper valve (23) being arranged in the fluid path between the annular gap (13) and the passage opening (45).

14. Vibration damper according to one of claims 1 to 13, characterized in that in the rebound stage, in order to compensate for the volume of damping medium displaced by the piston rod (15), at least the compensation chamber (21), the base valve (12) and the second working chamber (19) are fluidly connectable in the flow direction in this order and in the compression stage in the reverse order.

15. Vibration damper according to claim 14, characterized in that when the compensation module (20) is arranged externally, the damper valve (23) is arranged in the fluid path between the compensation chamber (21) and the bottom valve (12) and can be flowed through.

16. Vibration damper according to claim 14, characterized in that when the compensation module (20) is arranged internally, the compensation chamber (21) is fluidically connected directly to the inner tube (10).

17. Vibration damper according to one of claims 1 to 16, characterized in that the damper valve (23) is adjustable to adapt the damping effect in the fluid path of the bypass device (24).

18. Vibration damper according to one of claims 1 to 17, characterized in that the damper valve (23) for the force displaced by the piston rod (15) Volume of damping medium has an open passage (31) which is fluidly connected to the compensation chamber (21).

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