Vibration damper with a hydraulic-mechanical pressure stop

Abstract

Vibration damper with a hydraulic-mechanical pressure stop, comprising an axially displaceable piston rod with a piston that divides a working cylinder into a piston-rod-side and a piston-rod-remote working chamber, wherein the piston-rod-remote working chamber has a pressure cylinder whose volume is compressed during a retraction movement of the piston rod into the pressure cylinder, wherein additionally damping medium is displaced from the piston-rod-remote working chamber towards a compensation chamber, wherein the pressure cylinder comprises an elastomer body which is axially compressed by an end face of the piston rod and whose deformation throttles a flow connection between the piston-rod-remote working chamber and the compensation chamber.

Description

[0001] The invention relates to a vibration damper with a hydraulic-mechanical pressure stop according to the preamble of patent claim 1.

[0002] DE 198 29 765 A1 discloses a vibration damper with a hydraulic-mechanical pressure stop. It has a separate pressure cylinder within a working cylinder. The pressure cylinder comprises a separating piston, which is moved axially by a front end of the piston rod against a return spring, thereby displacing damping medium from the pressure cylinder via radial throttle openings in the wall of the pressure cylinder.

[0003] Between the pressure cylinder and the working cylinder, there is a circular flow connection that connects a working chamber remote from the piston rod with a compensation chamber. In this case, a bottom valve is also interposed, on whose bottom valve body the pressure cylinder rests.

[0004] In principle, the intended function of the pressure stop does not pose a problem. However, a noise that occurs between the piston rod and the separating piston is difficult to control. Another factor that negatively impacts the service life of the separating piston is the radial throttle openings, whose inner edges are in frictional contact with a sealing surface of the separating piston.

[0005] The object of the present invention is to provide a vibration damper with a pressure stop in which the problems known from the prior art are solved.

[0006] According to the invention, the object is achieved in that the pressure cylinder comprises an elastomer body which is axially compressed by an end face of the piston rod and, with its deformation, throttles a flow connection between the working chamber remote from the piston rod and the compensation chamber.

[0007] With the use of an elastomer body, direct contact with the piston rod is no longer a source of noise. Furthermore, the flow paths between the working chamber away from the piston rod and the compensation chamber are simplified, as the entire volume of damping medium displaced from the working chamber away from the piston rod is displaced through the flow connections. No bypass channels outside the hydraulic-mechanical pressure stop are required.

[0008] In a first variant, the flow connection runs between an outer surface of the elastomer body and an inner wall of the printing cylinder. In particular, a profiled surface of the elastomer body can be manufactured very easily.

[0009] Alternatively, the at least one flow connection can also run through the elastomer body.

[0010] The damping medium displaced from the working chamber away from the piston rod preferably flows axially through the pressure cylinder. Therefore, the pressure cylinder does not need to have radial openings, which tend to be more difficult to manufacture, and the reliable removal of burrs is particularly problematic.

[0011] To adapt the pressure stop to a preferred characteristic, the piston rod can have a profiled end face so that a progressively increasing displacement volume is immersed in the elastomer body depending on the stroke.

[0012] In an alternative embodiment, the elastomer body has a receiving opening for the piston rod's displacement volume, whereby the piston rod's displacement volume causes a radial expansion movement of the elastomer body depending on the insertion depth into the receiving opening. With the possibility of radial expansion of the elastomer body, the axial counterforce of the elastomer body is reduced in proportion to the expansion, in contrast to axial compression and the associated cross-sectional enlargement of the elastomer body. Thus, a significantly increased throttling effect is achieved in conjunction with the flow connection with reduced spring force of the elastomer body against the piston rod movement.

[0013] The intake port can be part of the flow connection. There is the advantageous option of closing the intake port at a defined immersion depth of the displacement volume, allowing for a damping force progression.

[0014] To limit the damping force progression, it can be provided that the piston rod axially penetrates the elastomer body from a defined stroke position in the area of ​​the displacement volume and in doing so releases a bypass channel for flow connection.

[0015] Alternatively or in combination, the elastomer body can have axially layered deformation areas with a different spring rate.

[0016] In order for the elastomer body to assume a defined installation position within the vibration damper and to maintain it even when the piston rod is extended, the pressure cylinder has a support edge that acts axially in the direction of the piston.

[0017] In a further advantageous embodiment, the support edge has an edge profile that provides open access to the flow connection between the piston rod-side working chamber and the compensation chamber. This eliminates the need for additional axial openings in the support edge.

[0018] It is also generally possible to have a profile between the cover side of the elastomer body and the support edge of the pressure cylinder, forming a section of the flow connection between the working chamber remote from the piston rod and the compensation chamber. The profile is preferably provided on the elastomer, as it is easier to manufacture there. For example, webs or nubs can serve as a free space for the flow connection.

[0019] The invention will be explained in more detail with reference to the following description of the figures.

[0020] It shows: Fig. 1 - 3 Vibration dampers with pressure cylinder and flow connection radially outside an elastomer body Fig. 4 Alternative version to Fig. 1 - 3 Fig. 5 Pressure stop with flow connection within the elastomer body Fig. 6 - 8 Further alternative version to Fig. 1 - 3 Fig. 9 - 11 Alternative variant based on Fig. 6 - 8

[0021] The Fig. Figure 1 shows a highly simplified view of a vibration damper 1 with a hydraulic-mechanical pressure stop 3. Within a working cylinder 5, an axially displaceable piston rod 7 is mounted with a piston 9, which divides the working cylinder 5, which is completely filled with a damping medium, into a working chamber 11; 13 on the piston rod side and a working chamber 15; 17 remote from the piston rod. The piston 9 can be equipped with damping valves 15; 17. An upper end in the area of ​​a generally known piston rod guide is not shown.

[0022] The working chamber 13, remote from the piston rod, has a pressure cylinder 19 as a component of the pressure stop 3, the volume of which is compressed when the piston rod 7 retracts into the pressure cylinder 19. In this exemplary embodiment, the pressure cylinder 19 is formed by a component additional to the working cylinder 5. In principle, the pressure cylinder 19 can also be realized by a longitudinal section of the working cylinder 5.

[0023] An elastomer body 21 is arranged within the pressure cylinder 19, which is axially compressed by an end face 23 of the piston rod 7 depending on the stroke position of the piston rod 7. In this case, the end face 23 is formed by a piston rod pin 24, which is axially positioned in front of the piston 9 in the direction of the elastomer body 21. The end face 23, together with the elastomer body 21, forms further components of the hydraulic-mechanical pressure stop 3.

[0024] Regardless of the stroke position of the piston rod 7, the damping medium displaced from the working chamber 13 remote from the piston rod during a retraction movement is conveyed via at least one flow connection 25 into a compensation chamber 27, which is delimited, for example, by an outer container tube 29 and the working cylinder 5 in conjunction with a bottom 31 of the container tube 29. In this embodiment, a bottom valve body 33 is arranged between the working chamber 13 remote from the piston rod and the compensation chamber 27. The bottom valve body 33 has a damping valve 35 effective during a compression movement and a check valve 37 opening during an extension movement of the piston rod 7 from the working cylinder 5.

[0025] The pressure cylinder 19 chambers the elastomer body 21 radially and axially. A base 39 serves for the axial chambering, which is axially supported, for example, via a spacer ring 41 on the base valve body 33. The base 39 has at least one passage opening 41 as part of the flow connection 25 between the working chamber 13 remote from the piston rod and the compensation chamber 27. Furthermore, the pressure cylinder 19 has a support edge 45 acting axially in the direction of the piston. This reliably secures the axial position of the elastomer body 21 within the pressure cylinder 19 and thus overall in the working chamber 13 remote from the piston rod.

[0026] The base 39 and the support edge 45 are connected to each other via a sleeve body 47. The sleeve body can be connected to the working cylinder 5, for example, by a material fit or a force fit. A form-fitting connection, for example, by means of a radial bead, is also conceivable.

[0027] In this exemplary embodiment, the flow connection 25 runs between an outer surface 49 of the elastomer body 21 and an inner wall 53 of the pressure cylinder 19, in particular the sleeve body 47.

[0028] In the Fig. 2, the piston rod 7 with its piston rod pin 24 is retracted into the pressure cylinder 19 via a through-opening 51 defined by the support edge 45, thereby slightly preloading the elastomer body 21. It can be seen that with the deformation of the elastomer body 21, the flow connection between the working chamber 13 remote from the piston rod and the compensation chamber 27 is throttled. For example, the annular region of the flow connection 25 between the outer surface 49 and the inner wall 53 can be reduced in cross-section. Depending on the design, the usable cross-section of the passage openings 43 in the base 39 can also be reduced by the radial expansion of the elastomer body 21 due to the axial compression. In any case, the damping medium displaced from the working cylinder 13 remote from the piston rod flows axially through the pressure cylinder 19 via the passage opening 51, the flow connection 25 and the passage openings 43.

[0029] With the Fig. 3 illustrates the progressive operating behavior of the hydraulic-mechanical pressure stop 3. The piston rod 7 has a profiled end face 23, so that a progressively increasing displacement volume is immersed in the elastomer body 21 depending on the stroke. Fig. 2, a displacer cross-section corresponding to the piston rod journal 24 acts. If this piston rod journal with this displacer cross-section is immersed deeper into the elastomer body 21, then in the further stroke of the piston rod journal 24, for example, a circumferential journal collar 55 with a significantly larger cross-section rests against the elastomer body 21 and displaces a correspondingly larger volume relative to the stroke of the piston rod 7.

[0030] The radial expansion of the elastomer body 21 is correspondingly greater, resulting in a greater throttling of the flow connection 25, which, however, is never completely interrupted. The mechanical force component of the pressure stop is determined by the elasticity or spring rate of the elastomer body 21. The flow connections 25 serve for the hydraulic component of the damping force of the pressure stop 3, creating a throttling effect when they constrict.

[0031] The design of the pressure cylinder 19 according to Fig. 4 differs from the execution according to the Fig. 1 to 3 in that the support edge 45 has an edge profile that forms an open access to the flow connection 25 between the working chamber 13 remote from the piston rod and the compensation chamber 27. The basic idea of ​​the edge profiling on the through-opening 51 is that the support edge 45 only has to partially achieve a supporting effect in order to hold the elastomer body 21 axially securely. The design clearance is correspondingly large in order to achieve the access to the flow connections 25 in the region of the outer surface 49 of the elastomer body. The through-opening can, for example, be designed as an oval. A through-opening 51 that is eccentric to the elastomer body 21 also fulfills this requirement, although this list of possibilities is by no means exhaustive. In this illustration, it can be seen that the inner wall 53 can also have axial grooves as part of the flow connection 25.

[0032] The variant according to Fig. 5 shows a structural modification of the pressure stop compared to the Fig. 1 to 4. Deviating from this, at least one flow connection 25 runs through the elastomer body 21. However, it is fundamentally possible that an additional flow connection 25B is present between the lateral surface 49 of the elastomer body 21 and the inner wall 53.

[0033] As a further option, the elastomer body 21 has axially layered deformation regions 21A; 21B with different spring rates. This allows a progressive effect to be achieved in addition to or as an alternative to a stepped end face 23 as a displacer.

[0034] With a profiling 57 between a cover side 59 of the elastomer body 21 and the support edge 45 of the pressure cylinder 19, a partial section of the flow connection 25 between the working chamber 13 remote from the piston rod and the compensation chamber 27 can be formed. Consequently, the geometry of the through-opening 51 can be switched more freely. Through-openings in the support edge 45 or the special edge profiling in the area of ​​the through-opening 51 can be omitted. In this case, the profiling 57 is implemented on the cover side 59 of the elastomer body 21, which tends to be easier to manufacture than a profiling on the inside of the support edge 45.

[0035] The Fig. 6 to 8 show a variant of the vibration damper 1 based on the basic construction according to the Fig. 1 to 3. Here, too, the piston rod 7 or the piston rod journal 24 has a profiled end face 23, so that a progressively increasing displacement volume 61 dips into the elastomer body 21 depending on the stroke. Deviating from this, the elastomer body 21 has a receiving opening 63 for the displacement volume 61 of the piston rod 7, wherein the displacement volume 61 of the piston rod 7 causes a radial expansion movement of the elastomer body 21 depending on the immersion depth into the receiving opening 63. The receiving opening 63 is designed, for example, as a stepped opening, the first section 63A of which is adapted to receive the displacement volume 61 of the piston rod journal 24. The displacement volume 61 of the piston rod journal 24 is preferably, but not necessarily, designed as a truncated cone, which, as the Fig. 6 and Fig. 7, serves to radially expand the annular elastomer body 21 and to throttle the flow connection 25 between the elastomer body 21 and the sleeve body 47. The receiving opening 61 extends over the entire axial length of the elastomer body 21 and thus forms a second flow connection, which is hydraulically connected in parallel to the first flow connection 25. At the latest when the piston rod pin 24 rests on a shoulder 65 within the exception opening 63, the second flow connection or the receiving opening for the flow of damping medium through the elastomer body 21 is at least throttled, or possibly also closed, whereby the hydraulic damping force component of the hydraulic-mechanical pressure stop 3 increases significantly. In this variant, too, a support edge 45 according to the embodiment according to the Fig. 1 to 3 can be used.

[0036] The Fig. Figures 9 to 11 show a vibration damper 1 which, at its hydraulic-mechanical pressure stop 3, has a limiting function for the hydraulic damping force component. Here, too, the piston rod pin 24 enters a receiving opening 63 of the elastomer body 21 and expands it radially to reduce the cross-section of the flow connection 25. In contrast to the design according to Fig. 6 to 8, the receiving opening 63 is designed without a shoulder, so that the piston rod journal 24 can completely penetrate the elastomer body 21 within the receiving opening 63. An outer circumferential surface 67 is provided, for example, with a bypass channel 69, which extends from the support edge 45 in the direction of the end face 23 of the piston rod journal 24. Between the bypass channel 69 and the end face 23, however, there is an axial closure section 71 of the piston rod journal 24. This bypass channel 69 to the flow connection 25 can alternatively also be reached from an axial channel in connection with a radial channel within the piston rod journal. The pressure stop 3 in the stroke positions of the piston rod according to the Fig. 9 and Fig. 10 is functionally identical to the pressure stop 3 in the Fig. 6 and Fig. 7. In this stroke position range, the bypass channel 69 is deactivated via the closure section 71. In the Fig.11 illustrates an overload protection device or an overload position of the piston rod 7, in which the piston rod 7 axially penetrates the elastomer body 21 from a defined stroke position in the area of ​​the displacement volume 61, thereby releasing the bypass channel 69 for the flow connection between the working chamber 13 remote from the piston rod and the compensation chamber 27. The axial compression and radial expansion of the elastomer body 21 are still possible even when the bypass channel 69 is activated. Reference symbol 1 vibration damper 3 Pressure stop 5 working cylinders 7 Piston rod 9 pistons 11 piston rod side working chamber 13 Working space remote from the piston rod 15 Damping valve 17 Damping valve 19 printing cylinders 21 elastomer bodies 23 End face of the piston rod 24 piston rod journals 25 Flow connection 27 Compensation room 29 Container pipe 31 Bottom of the container tube 33 bottom valve body 35 Damping valve 37 Check valve 39 Bottom of the printing cylinder 41 spacer ring 43 Passage opening 45 Support edge 47 sleeve bodies 49 Surface of the elastomer body 51 passage opening 53 Inner wall of the printing cylinder 55 tenon collar 57 Profiling 59 Cover page 61 displacement volume 63 Recording opening 65 paragraph in the receiving opening 67 Outer surface of the piston rod journal 69 Bypass channel 71 Piston rod journal closure section QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 198 29 765 A1

[0002]

Claims

[1] Vibration damper (1) with a hydraulic-mechanical pressure stop (3), comprising an axially displaceable piston rod (7) with a piston (9) which divides a working cylinder (5) into a working chamber (11; 13) on the piston rod side and a working chamber (11; 13) remote from the piston rod, wherein the working chamber (13) remote from the piston rod has a pressure cylinder (19) whose volume is compressed upon a retraction movement of the piston rod (5) into the pressure cylinder (19), wherein additionally damping medium is displaced from the working chamber (13) remote from the piston rod in the direction of a compensation chamber (27), characterized by that the pressure cylinder (19) comprises an elastomer body (21) which is axially compressed by an end face (23) of the piston rod (7) and, with its deformation, throttles a flow connection (25) between the working chamber (13) remote from the piston rod and the compensation chamber (27). [2] Vibration damper (1) according to claim 1, characterized bythat the flow connection (25) runs between an outer surface (49) of the elastomer body (21) and an inner wall (53) of the pressure cylinder (19). [3] Vibration damper (1) according to claim 1, characterized by that the at least one flow connection (25) runs through the elastomer body (21). [4] Vibration damper (1) according to at least one of claims 1 to 3, characterized by that the damping medium displaced from the working chamber (13) remote from the piston rod flows axially through the pressure cylinder (19). [5] Vibration damper (1) according to at least one of claims 1 to 4, characterized by that the piston rod (7; 24) has a profiled end face (23) so that a progressively increasing displacement volume (61) dips into the elastomer body (21) depending on the stroke. [6] Vibration damper (1) according to claim 5, characterized bythat the elastomer body has a receiving opening (61) for the displacement volume (61) of the piston rod (7), wherein the displacement volume (61) of the piston rod (7) causes a radial expansion movement of the elastomer body (21) depending on the immersion depth into the receiving opening (61). [7] Vibration damper (1) according to claim, characterized by that the receiving opening (63) is closed from a defined immersion depth of the displacement volume (61). [8] Vibration damper (1) according to claim, characterized by that the piston rod (7) axially penetrates the elastomer body (21) from a defined stroke position in the area of the displacement volume (61) and thereby releases a bypass channel (69) for flow connection. [9] Vibration damper (1) according to at least one of claims 1 to 8, characterized by that the elastomer body (21) has axially layered deformation areas with a different spring rate. [10] Vibration damper (1) according to at least one of claims 1 to 9, characterized by that the pressure cylinder (19) has a supporting edge (45) acting axially in the direction of the piston (9). [11] Vibration damper (1) according to claim 10, characterized by that the support edge (45) has an edge profile which has an open access to the flow connection (25) between the working chamber (13) remote from the piston rod and the compensation chamber (27). [12] Vibration damper (1) according to claim 10, characterized by that between a cover side (59) of the elastomer body (21) and the support edge (45) of the pressure cylinder (19) there is a profiling (57) which forms a partial section of the flow connection (25) between the working chamber (13) remote from the piston rod and the compensation chamber (27).

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