Shock absorber with hydraulic pressure stop

Abstract

The invention relates to a shock absorber with hydraulic pressure stop, comprising a cylinder which is filled with a damping medium and in which a piston rod is guided axially moveable, wherein the cylinder has a first piston which is fixed to the piston rod and slides on the inner wall of the cylinder, a second piston with a smaller nominal diameter is arranged on the piston rod axially spaced apart from the first piston, the second piston slides in a pressure cylinder depending on the stroke position of the piston rod, the pressure cylinder is formed relative to the cylinder by a separate pressure sleeve consisting of plastic, the pressure sleeve has a bottom, the pressure cylinder is supported on a metal base by a retaining connection, the pressure sleeve has a surrounding centring ring in the direction of the base which positions the pressure sleeve relative to the base, and the bottom of the base is coated on its top side with plastic, the coated surface of the bottom of the pressure sleeve and the base on the side of the base which faces away from the pressure sleeve are connected to one another by at least one bridge.

Description

Technical Field

[0001] This invention relates to a shock absorber with a hydraulic pressure stop. Background Technology

[0002] DE 10 2019 206 510 A1 discloses a shock absorber having a hydraulic pressure stop, the pressure cylinder of which includes a pressure sleeve and a base supporting the pressure sleeve. In the embodiment according to FIG9, the pressure sleeve includes a metal outer sleeve having a cylindrical insert made of plastic. The bottom of the pressure cylinder is formed by the cylindrical insert and the supporting bottom of the base. Both bottoms are designed to be flat, and they are formed to be parallel to the bottom surface of the pressure cylinder.

[0003] The pressure sleeve and the base are inextricably connected to each other by a central riveting element that passes through the bottom of the sleeve insert and the bottom of the support.

[0004] US 10 527 122 B2 also relates to a shock absorber with a hydraulic pressure stop. In this design, a pressure sleeve made entirely of plastic is used, which is connected to a metal base via an interface thread. Both the bottom of the pressure sleeve and the supporting bottom of the base are designed to be flat. Due to the interface thread, this construction is significantly more difficult to manufacture than the one according to DE 10 2019 206510. Summary of the Invention

[0005] The purpose of this invention is to simplify the structural design of shock absorbers with hydraulic pressure stops.

[0006] This objective is achieved by having a centering ring surrounding the pressure sleeve toward the base, which positions the pressure sleeve relative to the base, and the bottom of the base is coated with plastic on its top side, wherein the bottom of the pressure sleeve and the coated surface of the base on the side of the base opposite to the pressure sleeve are connected to each other by at least one bridging portion.

[0007] Therefore, this provides a highly pressure-resistant cylinder in which the connection between the pressure sleeve and the base is closed very simply through a plastic injection molding process for the pressure sleeve. Thus, no additional working steps are required for the connection.

[0008] In another advantageous design, the base has at least one step, wherein the outer side of the pressure sleeve extends to the radial support surface of the step. Thus, the support surface is the axially defined end of the coating surface on the base.

[0009] According to an advantageous design, at least one connection opening is formed in the step between the outer side of the pressure sleeve and the inner side of the base. The damping medium, extruded by the piston rod and flowing around the pressure sleeve, can flow away towards the bottom valve through the large-sized connection opening.

[0010] In order to allow the damping medium to flow out of the working space away from the piston rod as unrestricted as possible, at least a portion of the centering ring is formed on the outer side of the ring to form a surrounding gathering groove, which connects the outer side of the pressure sleeve to a plurality of connection openings in the base.

[0011] To optimize the use of structural space, the base surface of the gathering groove is inclined relative to the longitudinal axis of the pressure sleeve.

[0012] Preferably, the support ring of the bearing pressure sleeve of the base has a tapered shape towards the bottom of the pressure sleeve. Therefore, the base is generally strengthened, and the molding cost for forming the connection between the bottom and the support ring on the base is optimized.

[0013] The bottom of the base is preferably concave to distribute force evenly into the base.

[0014] One measure to increase the durability of the pressure cylinder is to form a ribbed profile on the coated surface of the base.

[0015] To optimize the flow path, the support ribs extend radially between the connection openings in the base. Therefore, complex closed channels are unnecessary.

[0016] To simplify the plastic injection molding process, the base has a directional lug on its bottom, through which it is oriented relative to the pressure sleeve. This ensures the base is oriented circumferentially in the injection mold, so that the mold slide, designed to engage the connection opening of the base, is always positioned to align with the connection opening.

[0017] The cylinder and base are optimally clamped axially within the damper, with the base for the cylinder having an annular contact surface that is not coated with plastic.

[0018] During the assembly of the shock absorber, the pressure cylinder, along with its body, is introduced into the receiving outer tube. For this purpose, it is advantageous that the side of the pressure sleeve has a radially offset clamping surface that forms an interference fit with the cylinder body. Therefore, during assembly, the pressure cylinder will not fall out of the cylinder body, which is open at both ends. Attached Figure Description

[0019] The invention will be explained in more detail with reference to the accompanying drawings. Wherein:

[0020] Figure 1 A longitudinal section of a shock absorber with a hydraulic pressure stop is shown;

[0021] Figure 2 It shows according to Figure 2 External view of the pressure cylinder;

[0022] Figure 3 and Figure 4 Cross-sectional views of the pressure cylinder are shown at different sections;

[0023] Figure 5 It shows according to Figure 2 A bottom view of the pressure cylinder. Detailed Implementation

[0024] The damper 1 includes a cylinder 3 completely filled with a damping medium, and a piston rod 5 is guided within the cylinder 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 matching the inner diameter Z1 of the cylinder 3, and the first piston divides the cylinder 3 into a working space 11 on the piston rod side and a working space 13 on the side away from the piston rod. The first piston 9 has: a damping valve 15 that generates a damping force during the retraction movement of the piston rod 5; and a damping valve 17 that generates a damping force during the extension movement.

[0025] Furthermore, a second piston 19 is fixed to the piston rod 5 and extends into a pressure cylinder 21 according to its stroke. This pressure cylinder has a pressure space 23 as part of a hydraulic pressure stop 25. A second component of the hydraulic pressure stop 25 is formed by the second piston 19. The second piston 19 has at least one throttling opening 27 through which damping medium discharged from the pressure space 23 flows into a working space 13 on the side away from the piston rod. To avoid abrupt changes in damping force during the retraction of the second piston 19 into the pressure cylinder 21, the pressure cylinder 21 has at least one tapered widening in the form of an entry ramp 28, which may also be implemented in combination with at least one throttling groove 29. The pressure cylinder 21 is a separate component relative to the cylinder body 3 and has an inner diameter Z2 smaller than the inner diameter Z1 of the cylinder body 3. Therefore, the second piston 19 also has a smaller nominal diameter D2 than the first piston 9.

[0026] like Figure 2 As shown, the pressure cylinder 21 has an axially extending groove 33 on its outer side 31, which is hydraulically connected in parallel with the pressure space 23 of the pressure cylinder 21.

[0027] Especially Figure 3 and Figure 4 As shown, the pressure cylinder 21 has a pressure sleeve 35 with a bottom 36, and the pressure cylinder 21 is supported on a base 37. The base 37 is placed on a bottom valve body 41 with its annular bridging portion 39, and the bottom valve body defines the cylinder body 3 on the end side of the piston rod 5 in the retraction direction.

[0028] The bottom valve body 41 includes a damping valve 43 that functions when flow comes in from the working space 13 on the side away from the piston rod, allowing the volume already extruded by the piston rod 5 to pass through. Additionally, the bottom valve body 41 has a check valve 45 that opens when flow comes from the balancing space 47 into the working space 13 on the side away from the piston rod, without generating any significant damping force. The balancing space 47 is defined by a receiving tube 49 surrounding the cylinder body 3, which, together with the outer wall of the cylinder body 3, forms an annular space partially filled with a damping medium and partially filled with gas. The bottom valve body 41 is supported on the bottom 51 of the receiving tube 49. The bottom 51 of the receiving tube 49, the receiving tube 49, and the piston rod guide 7 form a clamping chain for the cylinder body 3, the base 37, and the bottom valve body 41, as the cylinder body 3 is axially supported on the annular bridging portion 39 of the base 37. Therefore, the base 37 is fixed axially in two directions.

[0029] During the retraction of piston rod 5 within a certain range, only the first piston 9, or more precisely, the damping valve 15 for the retraction direction, is activated. At this time, the second piston 19 is always axially positioned outside the pressure cylinder 21. If it leaves this comfort zone, the second piston 19 retracts into the pressure cylinder 21, thereby reducing the volume of the pressure space 23, and the damping medium is squeezed from the pressure space 23 through the throttle opening 27 into the working space 13 on the side away from the piston rod. Thus, the first piston 9 and the second piston 19 generate significantly greater damping force through their damping valves 15, 27, since the two damping valves 15, 27 are hydraulically connected in parallel. Therefore, all the damping medium squeezed out by piston rod 5 can flow from the working space 13 on the side away from the piston rod through the damping valve 43 into the balance space 47 via the axially extending groove 33 in the pressure sleeve 35.

[0030] Figure 3 and Figure 4 The pressure cylinder 21 is shown in different cross-sections. It can be seen that the pressure cylinder 21 has a pressure sleeve 35 made entirely of plastic. Towards the base 37, which is made of metal, the pressure sleeve 35 of the pressure cylinder 21 has a surrounding centering ring 53 that positions the pressure sleeve 35 relative to the base 37. The outer surface 31 of the pressure sleeve 35 (in this case, the centering ring 53) also has a radially offset clamping surface 55 that forms an interference fit with the cylinder body 3.

[0031] The bottom 57 of the base 37 is coated with plastic on its top sides 59 and 61. The bottom 36 of the pressure chamber 23, which is defined at the end of the pressure sleeve 35, and the coated surface 63 of the base 37 on the side of the base 37 opposite to the pressure sleeve 35 are connected to each other via at least one bridging portion 65. For this purpose, the bottom 57 of the base 37 has a through hole 67. Therefore, the bottom 57 of the base 37 is a reinforcement of the entire bottom 36 of the pressure cylinder 21. In principle, multiple bridging portions 65 serving a connecting function can also be provided. In this embodiment, the bridging portion is designed as a centrally located, bolt-like bridging portion. However, if structural space requires, one or more eccentric bridging portions 65 can also be provided.

[0032] The base 37 has at least one step 69 connecting the recessed bottom 57 of the base 37 to the annular bridging portion 39 located on the bottom valve body 41. The support ring 71 of the pressure sleeve 35 of the base 37 has a tapered shape toward the bottom 36 of the pressure sleeve 35. Thus, a slightly inclined stepped shape is obtained at the base 37. The outer side 31 of the pressure sleeve 35 extends to the radial support surface 73 of the step. The support surface 73 not only forms the axial end of the pressure sleeve 35, but also additionally has an annular contact surface 75 for the cylinder body 3, which has no plastic coating.

[0033] Within the step 69 of the base 37, at least one connection opening 77 is formed between the outer side of the pressure sleeve 35 and the inner side of the base 37. The connection opening 77 conveys the volume of damping medium flowing through the axial groove 33 of the pressure sleeve 35 between the working space 13 on the side away from the piston rod and the damping valve 43. The inlet and outlet cross sections of the connection opening 77 are surrounded by the plastic of the pressure sleeve 35. For simple and reliable production of the pressure sleeve 35, the bottom 57 of the base 37 has a directional lug 79 through which the base 37 is oriented relative to the pressure sleeve 35 and thus in an injection mold (not shown). The injection mold ensures that the connection opening 77 remains unoccupied, allowing the mold slide to enter the recess 81 of the base 37 without resistance.

[0034] The centering ring 53 forms at least part of the surrounding gathering groove 83 on the outer side of the axial section of the pressure sleeve 35, which connects to the outer side surface 31 of the pressure sleeve 35 and thus connects the axial groove 33 in the pressure sleeve 35 to the connection opening 77 in the base 37.

[0035] The base surface 85 of the gathering groove 83 is inclined relative to the longitudinal axis 87 of the pressure sleeve 35, thereby providing the gathering groove 83 with maximum depth.

[0036] Overall Figures 3 to 5As can be seen, except for the central functional opening 89 in the bottom of the pressure cylinder 37, the entire bottom 57 of the base 37 is provided with a coating surface 63. The coating also extends radially to the rear region of the support surface 73 inside the support ring 71 of the base 37. In addition, the coating surface 63 on the base 37 is formed with a rib profile, wherein the support ribs 91 extend radially between the connection openings 77 of the base 37.

[0037] List of reference numerals

[0038] 1. Vibration damper

[0039] 3 cylinders

[0040] 5 Piston rod

[0041] 7 Piston rod guide section

[0042] 9 First Piston

[0043] 11 Working space on the piston rod side

[0044] 13. Workspace on the side furthest from the piston rod

[0045] 15 Damping valve

[0046] 17 Damping valve

[0047] 19 Second Piston

[0048] 21 Pressure Cylinder

[0049] 23 Pressure Space

[0050] 25 Hydraulic pressure stop

[0051] 27 Throttling opening

[0052] 28. Conical widened section

[0053] 29 Throttling Groove

[0054] 31. Outer surface of the pressure cylinder

[0055] 33 Axial groove

[0056] 35 Pressure Sleeve

[0057] 36. Bottom of the pressure sleeve

[0058] 37 Base

[0059] 39. Circular bridging section

[0060] 41 Bottom valve body

[0061] 43 Damping valve

[0062] 45 Check valve

[0063] 47. Balance Space

[0064] 49 Receiving tube

[0065] 51 Bottom of the receiving tube

[0066] 53 Centering Ring

[0067] 55 Clamping surface

[0068] 57. Bottom of the base

[0069] 59 Top side of the base

[0070] 61 Top side of the base

[0071] 63 Coated surface

[0072] 65 Bridging section

[0073] 67 Through Hole

[0074] 69 steps

[0075] 71 Support ring

[0076] 73 Supporting Surface

[0077] 75 Contact Surface

[0078] 77 Connection opening

[0079] 79 directional lugs

[0080] 81. Recess

[0081] 83 Aggregation Groove

[0082] 85 base plane

[0083] 87. Longitudinal axis of the pressure sleeve

[0084] 89 Functional openings

[0085] 91 Support ribs

Claims

1. A vibration damper (1) having a hydraulic pressure stop (25), the vibration damper comprising a cylinder (3) which is filled with a damping medium and in which a piston rod (5) is guided in an axially movable manner, wherein The cylinder (3) has a first piston (9) fixed to the piston rod (5) and sliding on the inner wall of the cylinder (3). A second piston (19) with a smaller nominal diameter is arranged axially spaced from the first piston (9) on the piston rod (5). This second piston slides within a pressure cylinder (21) according to the stroke position of the piston rod (5). The pressure cylinder (21) is formed relative to the cylinder (3) by a separate pressure sleeve (35) made of plastic, having a bottom (36). The pressure sleeve (35) is characterized by having a surrounding centering ring (53) in the direction of the base (37) to position the pressure sleeve (35) relative to the base (37), and the bottom (57) of the base (37) is coated with plastic on its top side (59, 61), wherein the bottom (36) of the pressure sleeve (35) and the coated surface (63) of the base (37) on the side of the base (37) opposite to the pressure sleeve (35) are connected to each other by at least one bridging part (65). The base (37) has at least one step (69), wherein the outer side (31) of the pressure sleeve (35) extends to the radial support surface (73) of the step (69). At least one connection opening (77) is formed in the step (69) between the outer side (31) of the pressure sleeve (35) and the inner side of the base (37); The outer side of the centering ring (53) forms at least a portion of a surrounding gathering groove (83), which connects the outer side (31) of the pressure sleeve (35) to a plurality of connection openings (77) in the base (37). The base surface (85) of the gathering groove (83) is inclined relative to the longitudinal axis (87) of the pressure sleeve (35); and The support ring (71) of the base (37) that carries the pressure sleeve (35) has a tapered shape toward the bottom (36) of the pressure sleeve (35).

2. The damper of claim 1, wherein The bottom (57) of the base (37) is recessed.

3. The vibration damper according to claim 1, characterized in that, The coating surface (63) on the base (37) has a ribbed profile.

4. The vibration damper according to claim 3, characterized in that, The support rib (91) extends radially between the connection openings (77) of the base (37).

5. The vibration damper according to any one of claims 1 to 4, characterized in that, The bottom (57) of the base (37) has a directional lug (79) through which the base (37) is oriented relative to the pressure sleeve (35).

6. The vibration damper according to any one of claims 1 to 4, characterized in that, The base (37) for the cylinder (3) has an annular contact surface (75) without a plastic coating.

7. The vibration damper according to any one of claims 1 to 4, characterized in that, The outer side (31) of the pressure sleeve (35) has a radially offset clamping surface (55) that is interference-fitted with the cylinder (3).

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