Vibration damper with hydraulic pressure stop

Abstract

The invention relates to a vibration damper having a hydraulic pressure stop, comprising a working cylinder filled with a damping medium, in which a piston rod is guided in an axially movable manner, the working cylinder having a first piston which is fastened to the piston rod and which slides on the inner wall of the working cylinder, a second piston having a smaller nominal diameter is arranged on the piston rod at an axial distance from the first piston, which second piston slides in a working-cylinder-independent pressure cylinder of a pressure stop depending on the stroke position of the piston rod, the working cylinder and the pressure cylinder delimiting a flow connection, the flow connection is formed by a plurality of axially extending channels inside a profiled part and is located between the working chamber remote from the piston rod and another working chamber, and wherein the profiled part is formed by at least one profiled element separate from the working cylinder and the pressure cylinder.

Description

Technical Field

[0001] The invention relates to a shock absorber having a hydraulic pressure stop according to the preamble of claim 1 . Background Art

[0002] From the prior art, a shock absorber with a hydraulic pressure stop is known, which has a pressure cylinder that is closed at the bottom and is fixed inside a working chamber. Such a shock absorber comprises a first piston and a second piston axially spaced apart from it. The first piston divides the working cylinder into a working chamber on the piston rod side and a working chamber remote from the piston rod. In the working chamber remote from the piston rod, the second piston is usually arranged beyond the piston rod extension and extends into the pressure cylinder depending on the stroke position of the piston rod. The outer diameter of the second piston is smaller than the outer diameter of the first piston.

[0003] The pressure cylinder and the working cylinder form a flow connection between the working chamber remote from the piston rod and a bottom valve, which connects the compensation chamber filled with damping medium. This flow connection is necessary when the second piston extends into the pressure cylinder and displaces the damping medium out of the pressure cylinder in the opposite direction of the displacement. Without this flow connection, hydraulic blockage of the shock absorber may occur. Therefore, the pressure cylinder in the patent document JPH 03102633 U or the patent document DE 11 2016 000 630 T5 has an outer rib profile, which is supported on the inner wall of the working cylinder. The axially extending rib profile forms a plurality of individual flow connections.

[0004] If the pressure cylinder is made of metal, the fins must have a certain width, since it is difficult to produce very thin fins by machining. Pressure cylinders made of sintered material are very expensive.

[0005] In patent specification DE 11 2016 000 630 T5, a pressure cylinder made of plastic is used which, however, must have a large wall thickness due to the high peak pressures in the pressure cylinder.

[0006] Patent document EP 3 295 051 A1 describes a pressure cylinder having a centering and fixing section, a conical transition section adjoining the centering and fixing section, and a length section adjoining the transition section for a displacement chamber. The centering section and the conical transition section represent loss regions with respect to the working capacity of the shock absorber, since in both sections neither the first piston nor the second piston can be used to generate a damping force. Summary of the invention

[0007] The object of the invention is achieved in that the profile is formed by at least one profile element which is independent of the working cylinder and the pressure cylinder.

[0008] A great advantage is that a very simple tube can be used as a semi-finished product for the pressure cylinder. If no inflow ramp is required for a moderate increase in damping force, no forming process step has to be performed. The profile element radially supports the pressure cylinder within the working cylinder and provides a sufficient residual cross section between the working cylinder and the pressure cylinder for the flow connection between the working chamber remote from the piston rod and the adjacent working chamber, which serves as a compensation chamber for the volume of damping medium displaced by the piston rod.

[0009] In a further advantageous embodiment, the profile element comprises a bent support region and a radial web region. The support region serves to fix the profile element. The wall thickness of the support region can therefore be selected to be relatively thin. The radial web region can also be designed very thin due to the configuration of the profile element as a bent sheet metal part, in particular if the pressure cylinder is dimensioned for the peak pressure in the pressure stop when viewed in isolation.

[0010] The profile element preferably has a curved support region, a radial web region and a curved second support region adjacent to the radial web region. For example, the profile element can be designed as a Z-shaped profile or can also be designed as an Ω-shaped profile in an expanded manner.

[0011] In order to achieve a defined orientation of the pressure cylinder within the working cylinder, the support region rests either against the inner wall of the working cylinder or against the outer wall of the pressure cylinder.

[0012] In order to distribute the radial load, a plurality of profile elements are combined to form a circumferential section with an axial groove profile. The circumferential section can then be distributed in the annular space between the pressure cylinder and the working cylinder, for example.

[0013] The structural solution in which a plurality of profile elements are combined to form a tubular body with an axial groove profile allows particularly easy assembly. The pressure cylinder is completely surrounded by the tubular body in the circumferential direction. The tubular body can be formed here from a rolled-up sheet metal body with axial reinforcement ribs or from a cylindrical part with subsequently introduced axial grooves. The tubular body can have abutments to fulfill its retaining function.

[0014] In principle, it may also be expedient to configure at least two profile elements axially spaced apart between the working cylinder and the pressure cylinder. This design may be used, for example, if the pressure cylinder has an enlarged inlet diameter in the direction of the second piston and a smaller bottom diameter.

[0015] In particular, the profile element is designed to be elastic in the radial direction when it is clamped between the working cylinder and the pressure cylinder with an interference fit.

[0016] According to an advantageous dependent claim, at least a part of the supporting region is connected to the working cylinder or pressure cylinder in a materially connected manner. The material connection can be realized, for example, by means of a welded connection, an adhesive connection or a soldered connection. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The present invention will be explained in more detail with reference to the following drawings, wherein:

[0018] Figure 1 A longitudinal section of the shock absorber is shown;

[0019] Figure 2 Shows Figure 1 Detailed illustration of

[0020] Figure 3 A cross section through the shock absorber in the region of the pressure cylinder is shown;

[0021] Figure 4 Shows Figure 3 Alternative variants of

[0022] Figure 5 An embodiment of the invention is shown having two axially spaced-apart profile elements. DETAILED DESCRIPTION

[0023] The present invention is described by taking the shock absorber 1 of the structure of a double-tube shock absorber as an example, but the present invention is not limited to this structure.

[0024] The shock absorber 1 comprises a working cylinder 3 which is completely filled with a damping medium and in which a piston rod 5 is guided in an axially movable manner. A piston rod guide 7 closes one end of the cylinder 3. A first piston 9 is fixed to the piston rod 5, the nominal diameter D1 of the first piston being adapted to the inner diameter Z1 of the cylinder 3 and the first piston dividing the cylinder 3 into a working chamber 11 on the piston rod side and a working chamber 13 remote from the piston rod. The first piston 9 has a damping valve 15 which generates a damping force during the retracting movement of the piston rod 5 and a damping valve 17 which generates a damping force during the retracting movement of the piston rod 5.

[0025] In this figure, an optional pull stop 19 is arranged in the working chamber 11 on the piston rod side, which has a pull stop spring 21 supported on the piston rod guide 7. In the direction of the piston 9, the pull stop spring 21 has a spring seat 23, which is operatively connected to a follower ring 25 on the piston rod 5 in a stroke-dependent manner.

[0026] Furthermore, a second piston 27 is fixed to the piston rod 5 and extends into a pressure cylinder 29 having a pressure chamber 31 in a stroke-dependent manner. (See also Figure 2). The second piston 27 has at least one throttling opening 33, through which the damping medium displaced from the pressure chamber 31 by the second piston 27 can flow into the working chamber 13 away from the piston rod. In order to avoid extreme damping force mutations, the pressure cylinder 29 has at least one inflow bevel 35, which can also be constructed in combination with the throttling groove 37. The pressure cylinder 29 is a separate component relative to the cylinder 3 and its inner diameter Z2 is smaller than the inner diameter Z1 of the cylinder 3. Therefore, the second piston 27 also has a smaller rated diameter D2 than the first piston 9. (See also Figure 2 )

[0027] The pressure cylinder 29 has a sleeve 39 and a bottom 41, wherein the pressure cylinder 29 is supported on a bottom valve body 45, for example, via a support sleeve 43. The bottom valve body 45 in turn protrudes from the bottom 47 of the outer container tube 49 and delimits the cylinder 3 at the end. An annular space is present between the inner wall of the working cylinder 3 and the outer wall of the pressure cylinder 29, which annular space is a flow connection 51 between the working chamber 13 remote from the piston rod and the bottom valve body 45.

[0028] The bottom valve body 45 comprises a damping valve 53, which acts when there is an inflow from the working chamber 13 remote from the piston rod and allows the volume displaced by the piston rod 5 to pass through. In addition, the bottom valve body 45 has a non-return valve 55, which opens when there is an inflow from the compensation chamber 57 into the working chamber 13 remote from the piston rod and does not generate any significant damping force. The compensation chamber 57 is delimited by a container tube 49 surrounding the working cylinder 3, which together with the outer wall of the working cylinder 3 forms an annular chamber which is partially filled with a damping medium and partially filled with a gas.

[0029] During the piston rod stroke movement of the second piston 27 outside the pressure cylinder, a damping force is generated exclusively by the damping valve 15 or 17 , depending on the direction.

[0030] If the second piston 27 extends into the pressure cylinder 29 during the retraction movement of the piston rod, the volume of damping medium located in the pressure chamber 31 is displaced through the throttle opening 33 against the retraction movement of the second piston 27 into the working chamber 13 remote from the piston rod and can flow out via the flow connection 51 in the direction of the bottom valve body 45. Another path opposite to the damping valve 53 is opened by at least one connecting opening 69 in the support sleeve 43.

[0031] During the extension movement of the piston rod, damping medium can flow from the compensation chamber 57 through the nonreturn valve 55 and the connecting opening 69 in the support sleeve 43 to the flow connection 51 in the direction away from the working chamber 13 of the piston rod.

[0032] Figure 3The cross section of the flow connection 51 formed by the working cylinder 3 and the pressure cylinder 29 between the working chamber 13 remote from the piston rod and the bottom valve 45, more precisely the compensation chamber 57 adjacent to the bottom valve, is shown. The flow connection 51 is formed by a plurality of axially extending channels 59 in a shaped part, which is formed by at least one profile element 61 which is independent of the working cylinder 3 and the pressure cylinder 29. Figure 3 Various embodiments of the profile element 61 in the flow connection designed as an annular chamber are shown.

[0033] In the simplest design, the profile element 61 comprises a curved support region 63 and a radial web region 65. In order to achieve the most comprehensive contact possible, the curved support region 63 is adapted to the outer diameter of the pressure cylinder 29. However, it is more advantageous for the production process if the profile element 61 has a curved support region 63, a radial web region 65 and a curved second support region 67 adjoining the radial web region. This design then has, for example, a Z-shaped or Ω-shaped form.

[0034] In principle, the support area can either rest on the inner wall of the working cylinder 3 (the left embodiment in the figure) or on the outer wall of the pressure cylinder 29 (the upper right embodiment in the figure). However, in order to prevent the profile element 61 from being incorrectly oriented, i.e. the support area for the pressure cylinder resting in an incorrect manner on the inner wall of the working cylinder, a profile element with an Ω shape is more reliable in production. The raised part (radius) of the radial web area 65 rests on the inner wall of the working cylinder 3.

[0035] According to the present invention Figure 4 In the embodiment shown, a plurality of profile elements 61 are combined to form a circumferential section with an axial groove profile for the channel 59. In a further development, a plurality of profile elements 61 are combined to form a tubular body with an axial groove profile for the channel 59. Due to the corrugated shape of the tubular body, almost the entire cross section of the flow connection 51 is occupied. In addition, the pressure load applied to the profile elements, more precisely to the tubular body, is relatively low.

[0036] Regardless of the specific design of the profile element 61, it is designed to be elastic in the radial direction in order to generate a certain radial stress, which centers the pressure cylinder 29 inside the working cylinder 3. This elasticity is achieved in particular by the material thickness and the shape of the profile element 61, because the angle between the support area 63 and the radial web area 65 deviates from a right angle, thereby promoting the deformation of the radial web area 65 in the circumferential direction. A similar effect is also achieved when the radial webs are part of an omega shape.

[0037] Figure 5A pressure stop is shown, in which at least two profile elements 61A, 61B are configured axially spaced apart between the working cylinder 3 and the pressure cylinder 29. For example, two tubes are configured here as profile elements 61A, 61B, wherein the first tube 61A is arranged near the inflow bevel 35 and the second tube 61B is arranged near the bottom 41. This solution reduces the mass of the profile element 61 and simplifies the application of the design for the pressure cylinder 29, in which the diameter at the inflow opening is larger than the diameter in the bottom area.

[0038] Preferably, at least a portion of the support area 63 is connected to the working cylinder 3 or the pressure cylinder 29 in a material connection. Examples of material connections are adhesive connections or soldering connections as well as welded connections. Since the loads between the at least one profile element 61 and the adjacent load-bearing component, i.e. the pressure cylinder 29 or the working cylinder 3, are low, no high requirements are placed on the load-bearing capacity of the material connection.

[0039] During the production of the shock absorber 1 , the pressure cylinder 29 is preferably connected to at least one profile element 61 . The pressure cylinder 29 is then pressed into the working cylinder 3 and the bottom valve body 45 is placed on the open end of the working cylinder 3 .

[0040] List of reference numerals:

[0041] 1 Shock absorber

[0042] 3 cylinders

[0043] 5 Piston rod

[0044] 7 Piston rod guide

[0045] 9 First Piston

[0046] 11 Working chamber on the piston rod side

[0047] 13 Working chamber away from piston rod

[0048] 15 Damping valve

[0049] 17 Damping valve

[0050] 19 Pull stop

[0051] 21 Pull stop spring

[0052] 23 Spring seat

[0053] 25 Follower ring

[0054] 27 Second piston

[0055] 29 Pressure Cylinder

[0056] 31 Pressure chamber

[0057] 33 Throttle opening

[0058] 35 Inflow slope

[0059] 37 Throttle groove

[0060] 39 Sleeve

[0061] 41 bottom

[0062] 43 Support sleeve

[0063] 45 bottom valve body

[0064] 47 Bottom of container tube

[0065] 49 Container tube

[0066] 51 Flow connection

[0067] 53 Damping valve

[0068] 55 Check valve

[0069] 57 Compensation cavity

[0070] 59 channels

[0071] 61 Profile elements

[0072] 61A Profile Components

[0073] 61B Profile Components

[0074] 63 Support Area

[0075] 65 Radial connecting piece area

[0076] 67 Second support area

[0077] 69 Connection opening.

Claims

1. A shock absorber (1) with a hydraulic pressure stop (27, 29), comprising a working cylinder (3) filled with a damping medium and in which a piston rod (5A, 5B) is guided axially movable, in, The working cylinder (3) has a first piston (9) fixed to the piston rod (5), the first piston sliding on the inner wall of the working cylinder (3), wherein a second piston (27) with a smaller rated diameter is arranged on the piston rod (5) axially spaced apart from the first piston (9), the second piston sliding in a pressure cylinder (29) of the pressure stop member independent of the working cylinder according to the stroke position of the piston rod (5), wherein the working cylinder (3) and the pressure cylinder (29) define a flow connection (51), the flow connection being formed by a plurality of axially extending channels (59) inside the molding and being located between a working chamber (13) remote from the piston rod and another working chamber (57), characterized in that the molding is formed by at least one profile element (61, 61A, 61B) independent of the working cylinder (3) and the pressure cylinder (29).

2. The vibration absorber according to claim 1, It is characterized in that The profile element (61) comprises a curved support region (63) and a radial web region (65).

3. The vibration absorber according to claim 2, It is characterized in that The profile element (61) has a curved support region (63), a radial web region (65) and a curved second support region (67) adjoining the radial web region.

4. The vibration absorber according to any one of claims 1 to 3, It is characterized in that The supporting areas (63, 67) bear against the inner wall of the working cylinder (3) and / or the outer wall of the pressure cylinder (29).

5. The vibration absorber according to any one of claims 1 to 4, It is characterized in that A plurality of profile elements (61) are combined to form a circumferential section having an axial groove profile.

6. The vibration absorber according to any one of claims 1 to 5, It is characterized in that A plurality of profile elements (61, 61A, 61B) are combined to form a tubular body having an axial groove profile (59).

7. The vibration absorber according to any one of claims 1 to 6, It is characterized in that At least two profile elements (61A, 61B) are axially spaced apart between the working cylinder (3) and the pressure cylinder (29).

8. The vibration absorber according to any one of claims 1 to 7, It is characterized in that The profile elements (61, 61A, 61B) are designed to be elastic in the radial direction.

9. The vibration absorber according to any one of claims 1 to 8, It is characterized in that At least a portion of the supporting region (63) is connected to the working cylinder (3) or the pressure cylinder (29) in a materially connected manner.

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