Throttling point for vibration damper

Abstract

The invention relates to a throttle point (37) for a vibration damper (3), comprising a variable-diameter valve body (35) which is guided in an annular groove (33) of a valve support (29) and which assumes a throttle position starting from a flow position by a radial closing movement towards a flow guide surface (39) as a function of a flow velocity of a damping medium in the throttle point, the throttle point has a centering device for the valve body, the centering device having a centering ring (95) which is mounted in a radially floating manner.

Description

Technical Field

[0001] The invention relates to a throttle point for a vibration damper according to the preamble of claim 1 . Background Art

[0002] DE 10 2016 210 790 A1 discloses a throttle point having an annular valve body with a variable diameter, which performs a radial closing movement depending on the flow velocity in the throttle point, thereby varying the throttle cross section of the throttle point.

[0003] The valve body has a transverse slit and is radially elastic or consists of segments that can move relative to one another. In one embodiment, the valve body has an outer shape that, when the valve element reaches its maximum expansion, rests against the inner wall of the cylinder, more specifically, the flow-guiding surface. In the initial position of the valve body, i.e., at its maximum distance from the flow-guiding surface, the valve body is not centered relative to the flow-guiding surface.

[0004] In document DE 10 2021 201 441 A1, when the valve body of a throttle valve using the same operating principle is in its starting position, i.e., at its maximum distance from the flow-guiding surface, the valve body is centered in the area of ​​the annular groove by means of the design of the valve seat. This measure is intended to ensure reproducible operating characteristics of the throttle valve.

[0005] Document DE 10 2020 209 113 A1 describes a throttle with a stop formed by the valve seat of the throttle. This stop determines the maximum expansion of the valve body. In one embodiment, the valve seat has a rigid circumferential edge. Other variants include components supported on a rigid annular web at the edge. Maintaining the manufacturing tolerances of the valve seat can minimize damping force deviations, especially in designs made of sintered metal, but this is limited by manufacturing precision.

[0006] The operating characteristics of the throttle point can be significantly improved by internal centering of the valve body. Summary of the Invention

[0007] Nevertheless, the aim remains to minimize the influence of manufacturing tolerances on the operating characteristics of the universal throttle.

[0008] This object is achieved in that the centering device comprises a centering ring which is mounted in a radially floating manner.

[0009] A simple centering ring allows for extremely precise adjustment of the inner diameter. This also results in precise running characteristics of the throttle.

[0010] In order to achieve a reliable centering function, the centering ring is fixed axially inside the annular groove.

[0011] In a further advantageous embodiment, the centering ring has a securing contour which engages in the gap between the groove sidewalls of the annular groove and the valve body. This ensures that the valve body is adequately secured in the axial direction without requiring permanent contact between the centering ring and the groove sidewalls.

[0012] Preferably, the fixing contour is formed by at least one radially inwardly directed tongue of the centering ring. This tongue can be oriented at slightly different angles relative to the centering ring, for example, in order to thereby minimize the axial play of the centering ring in the annular groove.

[0013] Furthermore, the securing contour can have a sliding contour facing the groove side wall, so that the centering ring does not have to slide on the end face and possibly tilt in the process.

[0014] For example, it can also be provided that the centering ring is designed as a body that is closed in the circumferential direction in order to precisely determine the maximum throttle position of the valve body.

[0015] Alternatively, the centering ring can also be designed to be elastic in the radial direction, so that any diameter of the valve ring can be adjusted.

[0016] The centering ring preferably offers only a slight resistance to the expansion movement of the valve body. Its sole purpose is to maintain a momentary stop function, by which the valve body is centered in the annular groove. If the centering ring has an axially extending gap, this mechanical resistance can be kept very low. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The present invention is further explained with reference to the following description of the drawings.

[0018] The accompanying drawings show:

[0019] Figure 1 shows a section through the shock absorber in the region of the damping valve arrangement;

[0020] Figure 2 Shown Figure 1 A top view of the valve body of the throttle valve shown;

[0021] Figures 3 and 4 Shown through the Figure 1 A cross-sectional view of the throttling device of the damping ring shown;

[0022] Figures 5 and 6 Shown Figure 2 and Figure 3 Alternative variants of the embodiment shown. DETAILED DESCRIPTION

[0023] Figure 1A damping valve arrangement 1 is shown for a shock absorber 3 of any design, which is only partially shown. The damping valve arrangement 1 comprises a first damping valve 5 having a damping valve body designed as a piston 7 which is fastened to a piston rod 9 .

[0024] The damping valve body 7 divides the shock absorber's cylinder 11 into a working chamber 13 on the piston rod side and a working chamber 15 remote from the piston rod. Both working chambers are filled with damping medium. Through-channels 17 and 19, each for a different flow direction, are formed on different pitch circles in the damping valve body 7. The design of these through-channels is merely exemplary. The outlet side of the through-channels 17 and 19 is at least partially covered by at least one valve disk 21 or 23.

[0025] Furthermore, the shock absorber has an optional tension stop 25 , which comes into contact with a cylinder-side stop surface, for example a piston rod guide 27 , after a defined extension movement of the piston rod 9 .

[0026] The pull stop 25 comprises a pull stop disc as a valve seat 29, which is fixed directly to the piston rod via a form-fit connection. For example, an annular elastomeric element 31 is positioned on the upper side of the valve seat 29. This elastomeric element has a low radial preload and remains in place even when the piston rod 9 vibrates. Starting from the stop point, the elastomeric element 31 acts as an additional supporting spring against the stop surface.

[0027] The valve support 29 has a circumferential groove 33 in which a valve body 35 of variable diameter is guided. The valve body 35 can expand in diameter and forms part of a throttle 37 as part of the damping valve arrangement 1. The valve body 35 forms the throttle 37 with the inner wall of the cylinder 11, with the inner wall 39 serving as a flow-guiding surface. In principle, the present invention can also be implemented with a valve support that is separate from the pull-stop.

[0028] The valve body 35 carries a return spring 41 on the outside, which is exemplified in this embodiment as a retaining ring. The return spring 41 can also optionally assume the function of limiting the expansion of the valve body 35.

[0029] When the piston rod speed is in the first operating range, for example, less than 1 m / s, the throttle 37 is fully open. The damping force is then generated solely by the through-channels 17 and 19 connected to the valve disks 21 and 23. When the valve disks 21 and 23 are subjected to flow impacts, they lift from their valve seat surfaces 47 and 49. This lifting motion is limited by the support disks 51 and 53, respectively.

[0030] In the second operating range of piston rod speeds, where the piston rod speed is greater than the limit speed of the first operating range, i.e., greater than the exemplary value of 1 m / s, the valve body 35 transitions into the throttle position and thereby performs a closing movement in the direction of the flow-guiding surface 39. Due to the high flow velocity of the damping medium in the throttle region 37, which is in the form of an annular gap, a negative pressure is generated, which causes the valve body 35 to expand radially. However, in order to ensure that the throttle region 37 never becomes blocked, a defined minimum flow cross section is maintained by a return spring 41, or the valve body has an external configuration that, together with the flow-guiding surface 39, determines the minimum flow cross section.

[0031] Figure 2 By passing through Figure 1 The cross-section of the shock absorber 3 shown shows a top view of the valve body 35. For clarity, the valve support 29, the retaining ring 41, and the piston rod 9 are omitted. It can be seen that the valve body 35 has a transverse clearance 55, which reduces the pressure required for the radial expansion movement of the valve body 35. The figure shows the valve body 35 in the flow position, where the flow velocity is minimized. Therefore, the figure shows the maximum flow cross section 57. The flow cross section 57 is determined by the inner wall 39 of the cylinder 11 and the outer side 45 of the valve body 35.

[0032] The valve body 35 may have a contour 59 which limits the annular cross section between the valve body 35 and the inner wall 39 of the cylinder 11. In this figure, the limiting contour 59 is designed as a single radial projection on the side 45. This forms a C-shaped throttle cross section 57. Between the cam-shaped projection 59 and the inner wall 39 there is a throttle cross section 61 of significantly reduced width, which remains unchanged even during the maximum expansion movement of the valve body 35. The radial projection 59, i.e., the limiting portion, is dimensioned in this case so that it is only at the throttle point 37 ( Figure 1 Due to the relatively large circumferential extent of the radial contour 59, the distance between the side surface 45 and the inner wall 39 of the valve body 35 can be increased outside the region of the radial contour 59 if necessary, while maintaining the same operating performance.

[0033] also, Figure 2 The valve body 35 is shown to comprise at least two legs 63, 65, which are mounted in a movable manner around a rotary bearing 67. This feature is independent of the radial projection 59, but the two features can advantageously complement each other by forming the restrictive contour 59 as part of the rotary bearing 67, for example as a bearing pin.

[0034] In this embodiment, the legs 63, 65 overlap in the circumferential direction and the swivel bearing 67 is designed in the overlapping area. The two legs 63, 65 also overlap in the area of ​​the transverse gap 55 to minimize the harmful leakage cross section. Figure 1 As shown, the valve support 29 has two receiving openings 73 that accommodate the support pins 69. The receiving openings in the valve support 29 can be configured as simple through-holes, for example. The support openings 75 and 77 are configured similarly. However, to provide a certain amount of clearance within the rotating bearing, the support openings 75 and 77 can also be arranged along the circumference of the legs, thereby forming a groove. This type of support for the two legs 63 and 65 should be understood as an example. Alternatively, an embodiment without the receiving openings 73 and the support pins 69 in the valve support 29 is also possible.

[0035] When the throttle point 37 is activated, i.e., when the flow velocity in the throttle cross section 57 is correspondingly high, the two legs 63, 65 of the valve body perform a radial pivoting movement about the pivot bearing 67 in the direction of the inner wall of the cylinder 11. Even if the legs 63, 65 are in full contact, the throttle cross section 61 remains open, which determines the damping effect.

[0036] Figure 3 The valve support 29 is shown in a cross-section in the region of the throttle point 37. This enlarged view shows that the throttle point 37 has a pressure chamber 89 filled with damping medium between the inner side surface 85 of the valve body 35 and the groove bottom 87 of the annular groove 33. The damping medium is supplied to the pressure chamber 89 via at least one inlet opening 91 and is discharged via at least one outlet opening 93. The pressure level and the pressure acting on the side surface 85 are essentially set by the ratio of the cross-sections of the outlet opening 93 to the inlet opening 91.

[0037] In addition Figure 3 Also shown is a centering device 95, which includes a centering ring that is mounted in a radially floating manner. In its simplest form, the centering ring is designed as a simple ring that surrounds the valve body 35 from the outside. In the maximum flow position of the throttle 37, a radial gap exists between the valve body and the centering ring. During assembly, this radial gap is not strictly defined; in other words, due to the eccentric assembly of the centering ring and the valve body in the annular groove 33, the radial gap can vary in the circumferential direction of the valve body.

[0038] In the present variant, the centering ring is axially fixed within the annular groove. This improves the functionality of the centering ring, and prevents it from entering the recess 97 of the valve body 35 in the area of ​​the return spring 41. To achieve axial fixation, the centering ring has a fixing profile 99 that engages in the gap 101 between one of the groove side walls 81 or 83 of the annular groove 33 and the valve body 35. The fixing profile 99 is formed, for example, by at least one radially inwardly pointing tongue of the centering ring 95. To enable the centering ring 95 to move radially as easily as possible within the annular groove 33, the fixing profile has a sliding profile facing the groove side wall 83. This sliding profile can, for example, be formed by a coating. However, it can also be provided that the centering ring 95 is made of plastic and thus has a lower coefficient of friction when interacting with the metallic valve support 29.

[0039] In accordance with Figure 3 and Figure 4 In the embodiment, the centering ring 95 is configured as an object closed in the circumferential direction. The centering ring 95 is configured to center the valve body 35 at its maximum throttling position, see Figure 4 As already explained, Figure 3 The figure shows the undefined radial position of the valve body 35 in the annular groove 33, for example, when the piston rod 9 is at rest. As the piston rod 9 begins its working movement, damping medium is fed into the pressure chamber 89 and exerts pressure on the inner side 85 of the valve body 35 and, via the gap 101, on the inner wall 103 of the centering ring 95. Tests have shown that by applying pressure, the centering ring 95 can be precisely centered relative to the center axis of the valve seat and thus relative to the guide surface 39 without any time delay. In contrast, the valve body 35 reacts slightly slower to the applied pressure. When the pressure level in the pressure chamber 89 reaches a defined level, the valve body 35 occupies Figure 4 In the illustrated maximum expanded position, i.e., the maximum throttle position, the distance between the outer side 45 of the valve body 35 and the flow guide surface 39 is minimal. The valve body 35 then abuts the centering ring 95. When the pressure in the pressure chamber 89 decreases, the valve body 35 is uniformly returned to its maximum flow-through position by the return spring 41. Thus, even at low pressure levels in the pressure chamber 89, the valve body 35 can be centered in the annular groove 33. Each time the maximum throttle position of the valve body 35 is reached, the valve body 35 is centered again.

[0040] This embodiment of the throttle point 37 has in principle Figure 3 The difference is that the centering ring 95 is constructed to be elastic in the radial direction. Figure 3 and Figure 4The difference from the illustrated design is that the centering ring 95 already bears against the valve body 35 in the maximum flow position of the throttle portion 37. This design is not mandatory for the use of an elastic centering ring 95. The centering ring 95 can be used to center the valve body 35 in any position between the maximum flow position and the maximum throttle position.

[0041] The centering ring 95 preferably has an axially extending slot 105. In this variant, the centering ring 95 also centers itself in the annular groove 33 when the pressure chamber 89 is subjected to flow impacts. This self-centering is transmitted to the valve body 35 as soon as it abuts the centering ring 95. When the valve body 35 returns to a position with greater flow, the centering ring 95 also retracts radially.

[0042] List of reference numerals:

[0043] 1 Damping valve device

[0044] 3 shock absorbers

[0045] 5 First damping valve

[0046] 7 Damping valve body

[0047] 9 Piston rod

[0048] 11 Cylinder

[0049] 13 Working chamber on the piston rod side

[0050] 15 Working chamber away from the piston rod

[0051] 17 Through the channel

[0052] 19 Through the channel

[0053] 21 Valve disc

[0054] 23 Valve disc

[0055] 25 Pull stop

[0056] 27 Piston rod guide

[0057] 29 valve seat

[0058] 31 Elastomer elements

[0059] 33 Annular groove

[0060] 35 valve body

[0061] 37 throttle position

[0062] 39 inner wall

[0063] 41 Return spring

[0064] 45 Side

[0065] 47 Valve seat surface

[0066] 49 Valve seat surface

[0067] 51 support plate

[0068] 53 support plate

[0069] 55 Horizontal gap

[0070] 57 Flow cross section

[0071] 59 Contour

[0072] 61 throttle cross section

[0073] 63 legs

[0074] 65 legs

[0075] 67 Rotation support

[0076] 69 Support pin

[0077] 73 accommodating opening

[0078] 75 support opening

[0079] 77 Support opening

[0080] 79 groove side wall

[0081] 81 groove side wall

[0082] 83 joint seam

[0083] 85 Side

[0084] 87 groove bottom

[0085] 89 pressure chamber

[0086] 91 Inflow opening

[0087] 93 outflow opening

[0088] 95 pairs of central ring

[0089] 97 recess

[0090] 99 fixed profile

[0091] 101 Gap

[0092] 103 inner wall

[0093] 105 gap.

Claims

1. A throttle portion (37) for a vibration damper (3), comprising a valve body (35) of variable diameter, which is guided in an annular groove (33) of a valve support (29) and which, depending on the flow velocity of the damping medium in the throttle portion (37), assumes a throttle position starting from a flow position by a radial closing movement toward a flow guide surface (39), wherein: The throttle point (37) has a centering device for the valve body (35), characterized in that the centering device has a centering ring (95) which is mounted in a radially floating manner.

2. The throttle portion according to claim 1, characterized in that: The centering ring (95) is axially fixed inside the annular groove (33).

3. The throttle portion according to claim 2, characterized in that: The centering ring (95) has a fixing contour (99) which is inserted into a gap (101) between the groove side walls (79, 81) of the annular groove (33) and the valve body (35).

4. The throttle portion according to claim 3, characterized in that: The fixing contour (99) is formed by at least one radially inwardly directed tongue of the centering ring (95).

5. The throttle portion according to claim 4, characterized in that: The fixing profile (99) has a sliding profile towards the groove side wall (81).

6. The throttle point according to at least one of claims 1 to 5, characterized in that The centering ring (95) is configured as a closed body in the circumferential direction.

7. The throttle point according to at least one of claims 1 to 5, characterized in that The centering ring (95) is configured to be elastic in the radial direction.

8. The throttle portion according to claim 7, characterized in that: The centering ring (95) has an axially extending slot (105).

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