Vibration damper for a motor vehicle

Abstract

The present invention relates to a vibration damper (10) for a vehicle, comprising: a damper tube (14) filled with hydraulic fluid, a working piston (18) connected to a piston rod (20) and arranged to be movable back and forth within the damper tube (14), wherein the interior of the damper tube (14) is divided by the working piston (18) into a first working chamber (22) and a second working chamber (24), a pressure stop arrangement (48) with an additional piston (50) and a pressure stop receptacle (82) provided within the damper tube (14) for receiving the additional piston (50), wherein the additional piston (50) is arranged to be axially movable within the pressure stop receptacle (82) and separates a compression stage working chamber (56) within the pressure stop receptacle (82),wherein the auxiliary piston (50) and the piston rod (20) are arranged to be movable separately from each other and wherein a damping element (28) is arranged between the piston rod (20) and the auxiliary piston (50) to dampen the contact of the piston rod (20) with the auxiliary piston (50) in the compression stage.

Description

[0001] The invention relates to a vibration damper for a motor vehicle with a pressure stop arrangement.

[0002] From DE 10 2023 105 059 A1, a hydraulic vibration damper with a hydraulic pressure stop is known. A hydraulic pressure stop typically serves to provide additional damping in the compression stage of the vibration damper. In known vibration dampers, an additional piston dips into a pressure stop chamber, thus generating additional damping when the piston rod moves in the compression direction. The components interacting in the pressure damping process must typically adhere to very precise manufacturing tolerances in order to compensate for, for example, lateral forces on the piston rod. The production of these components is therefore usually very expensive. Furthermore, the installation space for a pressure stop is limited, particularly in vibration dampers with external damping valves or in monotube vibration dampers with external gas chambers.Furthermore, the noise generated when the additional damping is activated in the compression stage must be minimized to such an extent that this process is not audible to the driver of the motor vehicle.

[0003] Based on this, the object of the present invention is to provide a vibration damper with a pressure stop arrangement that is inexpensive to manufacture, easy to assemble and quiet.

[0004] This problem is solved according to the invention by a vibration damper having the features of independent device claim 1. Advantageous embodiments are described in the dependent claims.

[0005] A vibration damper for a vehicle comprises, according to a first aspect, a damper tube filled with hydraulic fluid, a working piston connected to a piston rod and arranged to be reciprocally movable within the damper tube, wherein the interior of the damper tube is divided by the working piston into a first working chamber on the piston rod side and a second working chamber further away from the piston rod. The vibration damper preferably also includes a sealing assembly that provides a fluid-tight seal for the damper tube on the piston rod side. Furthermore, the vibration damper comprises a pressure stop assembly with an additional piston and a pressure stop receptacle located within the damper tube for receiving the additional piston, wherein the additional piston is arranged to be axially movable within the pressure stop receptacle and separates a compression stage working chamber within the pressure stop receptacle.The auxiliary piston and the piston rod are arranged to be movable independently of each other. The vibration damper also has a damping element that is arranged between the piston rod and the auxiliary piston and is designed and arranged to dampen the contact of the piston rod with the auxiliary piston in the compression stage.

[0006] The auxiliary piston is arranged in the compression direction of the piston rod, the piston rod preferably being movable between a position in which it is spaced apart from the auxiliary piston and a position in which the piston rod rests against the auxiliary piston. During compression, the piston rod moves in the compression direction until it rests against the auxiliary piston and moves it in the compression direction as well. The damping element between the piston rod and the auxiliary piston reliably minimizes the noise generated by the piston rod striking the auxiliary piston.

[0007] The vibration damper is, for example, a single-tube or a multi-tube vibration damper. For instance, a multi-tube vibration damper for a vehicle comprises an outer tube and an inner tube arranged coaxially to it, wherein a compensating chamber for receiving hydraulic fluid is formed between the outer tube and the inner tube, and a working piston connected to a piston rod, which is arranged to move back and forth within the inner tube. The interior of the inner tube is divided by the working piston into a first working chamber on the piston rod side and a second working chamber furthest from the piston rod. The compensating chamber is preferably at least partially filled with a gas, particularly at its upper end. The outer tube preferably forms at least part of the housing of the vibration damper. The inner surface of the inner tube is preferably designed as a guide for the working piston.The working piston preferably has a valve assembly connecting the first and second working chambers. In a monotube vibration damper, no outer tube is provided. The inner tube is referred to as the damper tube and, as previously described with reference to the inner tube, accommodates the piston rod and the working piston.

[0008] In a multi-tube vibration damper, the damper particularly features a sealing assembly designed and arranged to fluidically seal the interior of the outer tube on the piston rod side. The piston rod end of the inner tube is preferably attached to the sealing assembly. Opposite the sealing assembly, at the end furthest from the piston rod, the compensation chamber and the second working chamber are preferably fluidically sealed by means of a base piece. The compensation chamber is preferably fluidically connected to the first or second working chamber via openings in the inner tube. For example, the compensation chamber is sealed to the inner tube by means of a base element. The sealing assembly is preferably arranged coaxially with the piston rod and surrounds it circumferentially.

[0009] In a monotube vibration damper, the damper particularly features a sealing assembly designed and arranged to fluidically seal the interior of the damper tube on the piston rod side. The piston rod end of the damper tube is preferably attached to the sealing assembly. Opposite the sealing assembly, at the end furthest from the piston rod, the interior of the damper tube is preferably fluidically sealed by means of an axially movable sealing element. The sealing element preferably separates a gas chamber adjoining it in the axial direction from the working chamber filled with hydraulic fluid.

[0010] In the following description, the term vibration damper refers to both a multi-tube vibration damper and a single-tube vibration damper, where the damper tube is the inner tube of a multi-tube vibration damper.

[0011] The pressure stop assembly is preferably arranged within the damper tube, particularly in the end region of the damper tube furthest from the piston rod, and preferably comprises the pressure stop receptacle and the auxiliary piston, which is axially movable within the pressure stop receptacle and preferably has its outer circumferential surface at least partially or completely in fluid-tight contact with the inner wall of the pressure stop receptacle. The auxiliary piston is preferably not attached to the piston rod. The auxiliary piston and the piston rod are, in particular, movably mounted relative to each other. The pressure stop assembly also includes a compression stage working chamber, which is separated by the auxiliary piston within the damper tube, particularly the pressure stop receptacle.

[0012] In the following, a movement in the direction of tension is understood to mean a movement in the direction of the locking package in the piston rod-side area of ​​the shock absorber, and a movement in the direction of compression is understood to mean a movement in the direction of the base piece in the area of ​​the shock absorber furthest from the piston rod.

[0013] According to a first embodiment, the damping element is attached to the piston rod or to the auxiliary piston. Optionally, the vibration damper has two or more damping elements, with at least one damping element being attached to the piston rod and at least one to the auxiliary piston. The damping element is attached, in particular, to the end face of the auxiliary piston facing the piston rod or to the end face of the piston rod facing the auxiliary piston.

[0014] According to a further embodiment, the piston rod or the auxiliary piston has a recess in which the damping element is arranged. Preferably, the piston rod has a contact surface for abutting the auxiliary piston, the contact surface being formed, in particular, on the end face of the piston rod facing the auxiliary piston. The recess is formed on the contact surface of the piston rod. Preferably, the auxiliary piston has a contact surface that faces the piston rod and is designed to abut the piston rod, in particular the contact surface of the piston rod. The contact surface of the auxiliary piston preferably forms the end face facing the piston rod and preferably has the recess in which the damping element is arranged.

[0015] The auxiliary piston preferably comprises a valve body with at least one or a plurality of axial through-bores, which are at least partially or completely covered on the piston rod side by valve discs. The valve discs are preferably pre-tensioned such that they allow flow from the pressure stage working chamber through the through-bores into the second working chamber above a certain pressure in the pressure stage working chamber. The through-bores, together with the valve discs, thus prevent a pressure increase in the pressure stage working chamber exceeding a certain value.

[0016] The valve body preferably has a radially outwardly projecting shoulder at its piston rod end, forming an axial contact surface for the throttling element. The throttling element is preferably mounted around the outer circumference of the valve body and is particularly designed and arranged such that it forms a fluid-tight seal with the inner wall of the damper tube. The throttling element has, for example, a through-hole through which hydraulic fluid can flow. The auxiliary piston preferably has a disk that is arranged at the end of the auxiliary piston furthest from the piston rod, particularly at the valve body. The valve body, the valve disks, and the disk are preferably connected by a connecting element, such as a screw or a rivet, for example with a washer. The disk preferably projects radially beyond the valve body and forms an axial contact surface for the throttling element.For example, the recess is formed in the connecting element, the valve body or the disc.

[0017] According to another embodiment, the volume of the recess is larger than the volume of the damping element. This offers the advantage that the damping element can be completely contained within the recess when it comes into contact with the auxiliary piston or piston rod, particularly without protruding from it. This significantly minimizes wear on the damping element. Preferably, the damping element has a volume that corresponds to approximately 50% to 95%, particularly 70% to 90%, and preferably 80% of the volume of the recess. Preferably, the damping element is designed such that, when the piston rod comes into contact with the auxiliary piston, it is elastically deformed in such a way that the piston rod at least partially bears against the auxiliary piston with its end face.In particular, the damping element is designed in such a way that, when the piston rod hits the auxiliary piston, it is elastically deformed so that it is completely located within the recess and does not protrude beyond the recess in the axial direction.

[0018] According to another embodiment, the damping element is made of an elastic material. The damping element is preferably made of an elastic material, such as rubber, in particular ECO black (rubber) or TEEE (thermoplastic).

[0019] According to a further embodiment, the damping element is designed and arranged such that, in a first position where the piston rod and the auxiliary piston are spaced apart, it protrudes axially from the recess, and in a second position where the piston rod and the auxiliary piston are in contact with each other, it is completely recessed. This minimizes wear on the damping element. Preferably, in the second position, the contact surfaces of the auxiliary piston and the piston rod are in contact with each other. The contact surfaces are preferably made of steel, so that an audible noise is produced when the contact surfaces collide without damping.

[0020] According to another embodiment, the damping element is designed to be annular, spherical, cuboid, cubic, pyramidal or conical.

[0021] According to another embodiment, the damping element is secured within the recess by means of a press fit. In particular, the damping element is secured in the recess by means of a force-fit, form-fit, and / or material-fit connection. A press fit offers a simple and secure method of securing the damping element.

[0022] According to a further embodiment, the damping element has a surface with at least one or a plurality of raised areas and depressions. Preferably, the end face of the damping element facing away from the recess has a plurality of raised areas and depressions, which are particularly evenly spaced apart from one another. Preferably, the end face of the damping element is corrugated.

[0023] The damping element is preferably crown-shaped. In particular, the damping element is annular in shape, with the end face facing away from the recess having a profile, such as waves or serrations.

[0024] According to another embodiment, the recess is cylindrical, hemispherical or annular in shape.

[0025] According to a further embodiment, a return element is arranged within the damping element. The return element is, for example, a wave spring, which is preferably arranged completely within the damping element. The return element is preferably made of a metal. Preferably, the return element has a contour that corresponds to the surface geometry of the end face of the damping element.

[0026] According to a further embodiment, the piston rod has a first piston rod section to which the working piston is attached, and a second piston rod section that extends from the working piston in the compression direction and to which the damping element is attached. The piston rod optionally also includes a second piston rod section, which, for example, is designed separately from the first piston rod section as an auxiliary piston rod, and extends from the working piston in the axial direction, particularly in the compression direction. The diameter of the second piston rod section preferably corresponds substantially to the diameter of the first piston rod section of the piston rod. The second piston rod section represents an axial extension of the piston rod.

[0027] The pressure stop receptacle preferably has a bypass opening formed at the piston rod end of the pressure stop receptacle. The bypass opening is preferably designed such that its flow cross-section decreases in the pressure direction. Preferably, the bypass opening is formed as an end-face notch in the pressure stop receptacle, with the area of ​​the bypass opening decreasing along the pressure stop receptacle in the pressure direction. The bypass path formed by the bypass opening has a flow cross-section that decreases when the auxiliary piston moves in the pressure direction. This increases the damping of the auxiliary piston during movement in the pressure direction, thus achieving, for example, progressive damping. Preferably, no bypass openings are formed in the area of ​​the pressure stop receptacle furthest from the piston rod.Thus, maximum damping is set before the additional piston hits the base piece.

[0028] Optionally, the vibration damper has an adapter mounted inside the damper tube for attaching a damping valve device or a flow passage formed in the damper tube for attaching a compensating device, wherein the additional piston is arranged between the adapter or the flow passage and the end of the damper tube furthest from the piston rod.

[0029] The vibration damper also optionally features a damping valve assembly, which is preferably attached to the damper tube by means of an adapter. The damping valve assembly is preferably fluidically connected to the second working chamber, in particular the interior of the damper tube, via the adapter. The damping valve assembly is, for example, a solenoid valve, which is particularly infinitely adjustable. Optionally, the damping valve assembly serves exclusively for additional damping in the compression stage.

[0030] The adapter is preferably located entirely within the damper tube, particularly within the working space of the damper tube furthest from the piston rod, and is preferably fixed to the damper tube. In the axial direction, the adapter is preferably spaced apart from the base piece. For example, the adapter is arranged and designed such that it limits movement of the auxiliary piston in the tensile direction. Optionally, the adapter forms an axial end stop for movement of the auxiliary piston in the tensile direction, with the tensile end stop abutting the adapter. The adapter is, for example, sleeve-shaped and particularly forms a reduction in the inner diameter of the damper tube.

[0031] The pressure stop receptacle is preferably designed in a sleeve-like shape. Preferably, the auxiliary piston rests fluid-tight against the inner wall of the pressure stop receptacle, with the pressure stop receptacle forming a guide for the auxiliary piston. Preferably, the auxiliary piston and the piston rod are movable independently of each other. This allows movement of the piston rod without the additional mass of the auxiliary piston during normal operation of the shock absorber, with the auxiliary piston being moved by the piston rod solely for compression damping within the pressure stop chamber.

[0032] Optionally, a spring element is arranged between the auxiliary piston and the end of the damper tube furthest from the piston rod. The pressure stop arrangement includes, in particular, the spring element, which preferably bears against the auxiliary piston and the end of the damper tube at their respective end regions. The spring element is, for example, a coil spring. Preferably, the spring element is pre-tensioned against the auxiliary piston so that it exerts a force on the auxiliary piston in the tensile direction.

[0033] Preferably, the auxiliary piston has a bypass channel and a throttling element for adjusting the flow cross-section of the bypass channel, the throttling element being mounted so as to be movable in the axial direction. The bypass channel is formed, in particular, between the valve body and the throttling element. The bypass channel is provided in addition to the through-holes and offers an additional flow channel when the auxiliary piston moves in the compression or tension direction.

[0034] In particular, the bypass channel is formed, at least partially, by recesses in the valve body. The recesses are preferably formed in the radially outward-facing circumferential surface of the valve body. The valve body has, for example, a plurality of recesses, which are arranged, in particular, at uniform intervals around their circumference. The disc, in particular, has a plurality of cutouts. The bypass channel is preferably formed by the cutouts in the disc, the recesses in the valve body, and the throttling element.

[0035] Preferably, the throttling element is designed and arranged such that in a first position it opens a first flow cross-section of the bypass channel and in a second position it opens a second flow cross-section of the bypass channel. According to a further embodiment, the first flow cross-section is smaller than the second flow cross-section. According to another embodiment, the throttling element is arranged such that it moves to the first position when the auxiliary piston moves in the compression direction and to the second position when the auxiliary piston moves in the extension direction. This allows the auxiliary piston to experience greater damping during compression than during extension. Thus, the auxiliary piston functions as a pressure stop with additional damping of the piston rod in the compression direction.

[0036] The throttling element is preferably arranged and designed such that, when the auxiliary piston moves in the compression direction, it rests against the shoulder of the valve body and at least partially or completely closes the bypass channel. Preferably, the bypass channel comprises a first flow cross-section, which ideally corresponds to the cross-section of the through-hole in the throttling element. The throttling element is preferably arranged and designed such that, when the auxiliary piston moves in the compression direction, it rests against a shoulder furthest from the piston rod, in particular against the disk, and opens the bypass channel, in particular the second flow channel.

[0037] For example, the throttle element is ring-shaped. The throttle element designed as a piston ring, for instance, has a slotted opening that forms a complete circumferential interruption of the ring-shaped piston ring. Description of the drawings

[0038] The invention is explained in more detail below with reference to several exemplary embodiments and the accompanying figures. Fig. Figure 1 shows a schematic representation of a vibration damper in a longitudinal sectional view according to an exemplary embodiment. Fig. Figure 2 shows a schematic representation of a partial section of a vibration damper in a longitudinal section view according to a further embodiment. Fig. Figure 3 shows a schematic representation of a partial section of the piston rod of the vibration damper in a perspective view according to a further embodiment. Fig. Figure 4a shows a schematic representation of a partial section of the piston rod of the vibration damper in a longitudinal section view according to a further embodiment. Fig. Figure 4b shows a schematic representation of a partial section of the piston rod of the vibration damper in a perspective view according to a further embodiment. Fig. Figure 5 shows a schematic representation of a partial section of a vibration damper in a longitudinal sectional view according to a further embodiment. Fig. Figure 6 shows a schematic representation of an additional piston in a longitudinal section view according to further embodiments.

[0039] Fig. Figure 1 shows a vibration damper 10, which is, by way of example, a multi-tube vibration damper, specifically a two-tube vibration damper. The vibration damper 10 has an outer tube 12, which forms an outer surface, in particular a housing, of the vibration damper 10. Inside the outer tube 12, a damper tube 14, also referred to as an inner tube 14, is arranged coaxially to it. A compensation chamber 16 is formed between the outer tube 12 and the inner tube 14, which is preferably at least partially or completely filled with a hydraulic fluid. For example, the compensation chamber 16 is partially filled with a gas.

[0040] Within the inner tube 14, a working piston 18, connected to a piston rod 20, is arranged such that it is movable within the inner tube 14, the inner tube preferably serving as a guide for the working piston 18. The working piston 18 preferably has a valve assembly. For example, the valve assembly comprises a rebound valve for damping the piston movement during the rebound stage and a compression valve for damping the piston movement during the compression stage. Preferably, the valves are each formed by a through-hole in the piston and a valve disc assembly. The working piston 18 divides the interior of the inner tube 14 into a first working chamber 22, located towards the piston rod, and a second working chamber 24, located further away from the piston rod. The end of the piston rod 20 protruding from the damper tube 14 is preferably connectable to the vehicle body.The piston rod 20 has, by way of example, a first piston rod section 21 that extends to the working piston 18 and to which the working piston 18 is attached. Preferably, the working piston 18 is attached to the end of the first piston rod section 21 opposite the end of the piston rod 20 that protrudes from the damper tube 14. The piston rod 20 includes, by way of example, a second piston rod section 44, in particular an additional piston rod 42, which connects to the working piston 18 in the axial direction, in particular in the pressure direction D. The additional piston rod 42 preferably forms an axial extension of the piston rod 20, in particular of the first piston rod section 21. The diameter of the additional piston rod 42 preferably corresponds substantially to the diameter of the first piston rod section 21 of the piston rod 20. By way of example, the additional piston rod 42 has two different diameters.In a first piston-rod-side region, the auxiliary piston rod 42 has, for example, a first diameter corresponding to the diameter of the piston rod 20. In a second region of the auxiliary piston rod 42, facing away from the piston rod, it has, in particular, a second diameter that is smaller than the first diameter. The second piston rod region 44 preferably has an axial length greater than the axial length of an adapter (not shown) for mounting a damping valve device. It is also included that the vibration damper 10 does not have a separate auxiliary piston rod 42. In this case, the piston rod 20 has an extension compared to the piston rod 20 of the [unclear]. Fig. 1 and Fig. 2. The piston rod 20 extends beyond the working piston 18 in the pressure direction D. Preferably, the extension is the portion of the piston rod 20 that extends beyond the working piston 18 in the pressure direction D. The extension is preferably formed integrally with the piston rod 20.

[0041] The interior of the outer tube 12 is fluidly sealed on the piston rod side by means of a sealing assembly 34. Opposite the sealing assembly 34, at the end furthest from the piston rod, the compensation chamber 16 is fluidly sealed by means of a bottom piece 36. The interior of the damper tube 14, in particular the second working chamber 24, is preferably also fluidly sealed by means of the bottom piece 36. It is also conceivable that a further bottom element is provided separately from the bottom piece, which seals the outer tube. Preferably, the vibration damper 10 does not have a bottom valve. The piston rod end of the inner tube 14 is preferably attached to the sealing assembly 34.

[0042] The outer tube 12 is preferably cylindrical and optionally has a smaller diameter at the piston rod end, which is at least partially enclosed by a cap 26. The cap 26 forms an end piece of the outer tube 12 and at least partially encloses the closure assembly 34.

[0043] The vibration damper 10 includes, for example, a pull stop 46, which is fixedly attached to the piston rod 20. The pull stop 46 is, for example, annular and arranged between the working piston 18 and the locking assembly 34 within the first working chamber 22. Preferably, the pull stop 46, in particular its end face facing the locking assembly 34, forms a stop surface for bearing against the locking assembly 34 when the piston rod moves in the pull direction Z. The pull stop 46 serves to limit the movement of the piston rod in the pull direction Z. The vibration damper 10 also includes, for example, a pull stop sleeve 30, which is coaxial with the damper tube 14 and attached to the end of the damper tube 14 on the locking assembly side. Preferably, the outer surface of the pull stop sleeve 30 rests against the inner surface of the damper tube 14.The pull stop sleeve 30 is preferably designed for axial guidance of the pull stop in the pull stage. Optionally, the vibration damper 10 does not have a pull stop sleeve 30, in which case a flow gap is formed between the pull stop 46 and the inner wall of the damper tube 14, through which the hydraulic fluid can flow during piston rod movement.

[0044] The vibration damper 10 optionally includes two or exactly one damping valve assembly (not shown in the figures) for damping the piston rod movement in the rebound and compression stages. The direction of movement of the piston rod 20 in the compression stage D and in the rebound stage Z is shown in Fig. Figure 1 illustrates this with arrows Z and D. The damping valve assembly is connected, for example, via the sleeve-shaped adapter (not shown), fluidically to the second working chamber 24, in particular the interior of the damper tube 14. The damping valve assembly is, for example, a solenoid control valve, which is, in particular, continuously adjustable. Optionally, the damping valve assembly serves exclusively for additional damping in the compression stage.

[0045] The vibration damper 10 includes, by way of example, a pressure stop arrangement 48, which is arranged within the damper tube 14, in particular in the end region of the damper tube 14 furthest from the piston rod. The pressure stop arrangement 48 preferably comprises a pressure stop receptacle 82 and an additional piston 50, which is axially movable within the pressure stop receptacle 82 and preferably bears at least partially or completely against the inner wall of the pressure stop receptacle 82 in a fluid-tight manner with its outer circumferential surface. Preferably, the additional piston 50 is axially movable within the pressure stop receptacle 82 such that the pressure stop receptacle 82 forms a guide for the additional piston 50. The additional piston 50 is, by way of example, not attached to the piston rod 20 or the additional piston rod 42.The pressure stop assembly 48 also includes, in particular, a spring element 52, which is preferably arranged between the auxiliary piston 50 and the base piece 36 and bears against them with its respective end regions. The spring element 52 is, for example, a coil spring. The auxiliary piston 50, in particular, separates a compression stage working chamber 56 within the pressure stop receptacle 82. The compression stage working chamber 56 is preferably arranged completely within the pressure stop receptacle 82. The pressure stop receptacle 82 is, for example, sleeve-shaped and, in particular, is fluid-tightly attached to the base piece 36 with its end furthest from the piston rod. Preferably, the pressure stop receptacle 82 bears fluid-tightly against the inner wall of the damper tube 14 with its outer diameter.

[0046] The spring element 52 rests against the additional piston 50 and the base piece 36 in the relaxed or slightly pre-tensioned state.

[0047] During operation of the shock absorber 10, and when the piston rod 20 moves in the compression direction D, the auxiliary piston rod 42 moves axially towards the auxiliary piston 50 and pushes the auxiliary piston 50 in the compression direction D towards the base piece 36, thereby tensioning the spring element 52. When the piston rod 20 subsequently moves in the extension direction Z, the auxiliary piston is pushed in the extension direction Z by means of the spring element 52 until it reaches its starting position.

[0048] The vibration damper 10 further comprises a damping element 28, which is arranged and designed such that, in the compression stage, it dampens the impact of the piston rod 20, in particular the auxiliary piston rod 42, against the auxiliary piston 50. The damping element 28 is preferably made of an elastic material, such as rubber, in particular ECO black (rubber) or TEEE (thermoplastic). The damping element 28 is spherically shaped by way of example. It is also conceivable that the damping element 28 is cuboid, cube-shaped, pyramid-shaped, or conical. Other geometric shapes with a square or round cross-section are also possible.

[0049] Preferably, the piston rod 20, and in particular the auxiliary piston rod 42, has a contact surface 38a for bearing against the auxiliary piston 50, wherein the contact surface 38a is formed, in particular, on the end face of the piston rod 20 facing the auxiliary piston 50. The piston rod 20, and in particular the auxiliary piston rod 42, has a recess 32 on the contact surface 38a in which the damping element 28 is arranged. The damping element 28 is preferably fastened within the recess, preferably by positive locking, force locking, and / or material locking. In particular, the damping element 28 is pressed in within the recess 32. By way of example, the recess 32 extends axially in the direction of the main piston 18 relative to the contact surface 38a.

[0050] Preferably, the volume of the recess 32 is larger than the volume of the damping element 28. Preferably, the damping element 28 has a volume that corresponds to approximately 50% to 95%, in particular 70% to 90%, preferably 80% of the volume of the recess 32. Preferably, the damping element 28 is designed such that, when the piston rod 20 strikes the auxiliary piston 50, it is elastically deformed in such a way that the piston rod 20 at least partially bears against the auxiliary piston 50 with its end face. In particular, the damping element 28 is designed such that, when the piston rod 20 strikes the auxiliary piston 50, it is elastically deformed in such a way that it is arranged completely within the recess 32 and does not project beyond the recess 32 in the axial direction.Preferably, the damping element 28 is designed and arranged such that in a first position, in which the piston rod 20 and the additional piston 50 are spaced apart from each other, it projects axially from the recess 32, and in a second position, in which the piston rod 20 and the additional piston 50 are in contact with each other, it is arranged completely within the recess 32.

[0051] Fig. Figure 2 shows a partial section of a shock absorber 10 according to Fig. 1 in an enlarged detail view, where Fig. 2 shows the vibration damper 10 in a position in which the piston rod 20 is not in contact with the auxiliary piston 50. The essential elements of the Fig. 2 correspond to those of the Fig. 1. Fig. Figure 3 shows a detailed view of an embodiment of the piston rod 20, wherein the recess 32 is, by way of example, cylindrical in shape.

[0052] Fig. Figures 4a and b show a further embodiment of a damping element 28, wherein the components of the vibration damper 10 are essentially the same as those of the Fig. 1 to 3 correspond. The damping element 28 of the Fig. 4a and b are exemplary crown-shaped. Optionally, the damping element 28 has a surface facing towards the auxiliary piston 50, which has at least one or more raised and recessed areas. For example, the surface is corrugated. By way of example, the damping element 28 is annular, with the surface facing towards the auxiliary piston 50 being corrugated. The recess 32 is also annular by way of example. Optionally, the damping element 28 has a return element, such as a wave spring, which is arranged, in particular, completely within the damping element 28.

[0053] In the Fig. In the position shown in Figure 5, the piston rod 20 is moved further in the compression direction D, with the auxiliary piston 50 bearing against the contact surface 38a of the piston rod 20 and preferably moving with the piston rod 20 in the compression direction D, whereby the spring element 52 is tensioned so that it exerts a force in the tension direction Z on the auxiliary piston 50, preferably increasing with movement in the compression direction D. In the Fig. In the position shown in Figure 5, the damping element 28 is arranged by way of example completely within the recess 32, with the contact surface 38a resting against the additional piston 50.

[0054] Fig. Figure 6 shows an additional piston 50 in detail. The additional piston 50 comprises a valve body 58 with at least one or a plurality of axial through-bores 60, which are covered by valve discs 62. The valve discs 62 are attached to the piston rod end of the valve body 58 and are pre-tensioned such that they allow flow from the pressure stage working chamber 56 through the through-bores 60 into the second working chamber 24 above a certain pressure in the pressure stage working chamber 56. The through-bores 60 together with the valve discs 62 thus prevent a pressure increase in the pressure stage working chamber 56 exceeding a certain value.

[0055] The auxiliary piston 50 includes, for example, a piston ring 64, which is arranged circumferentially around the valve body 58 and is, in particular, axially movable. The piston ring 64 is, for example, annular or cylindrical in shape. The valve body 58 has, for example, a radially outwardly projecting shoulder 66 at its piston rod-side end, which forms an axial contact surface for the piston ring 64. The piston ring 64 is designed such that it forms a fluid-tight seal with the inner wall of the damper tube 14. The piston ring 64 has, for example, a through-hole 76 through which hydraulic fluid can flow. The auxiliary piston 50 preferably has a disk 68, which is arranged at the end of the auxiliary piston 50, and in particular of the valve body 58, furthest from the piston rod. The disk 68 preferably projects radially beyond the valve body 58 and forms an axial contact surface for the piston ring 64.The valve body 58, the valve discs 62, and the disc 68 are preferably connected via a connecting element 78, such as a screw or a rivet, for example with a washer.

[0056] The piston ring 64 is preferably arranged around the valve body 58 such that it is axially, and in particular continuously, movable from a first position, in which it abuts the shoulder 66 of the valve body 58, to a second position, in which it abuts the disk 68. The valve body 58 preferably has recesses 70 on its outer surface, which are preferably aligned with cutouts 80 in the disk 68, so that a bypass channel 74 is formed between the pressure stage working chamber 56 and the working chamber 24 furthest from the piston rod.

[0057] When the auxiliary piston 50 moves in the pressure direction D, the piston ring 64 rests against the shoulder 66 of the valve body 58 and at least partially closes the bypass channel 74. The bypass channel 74 then comprises a first flow cross-section, which corresponds, for example, to the cross-section of the through-hole 76 in the piston ring 64. Fig. Figure 6 shows a position of the piston ring 64 during movement of the auxiliary piston 50 in the direction of pull Z, wherein the piston ring 64 rests against the disk 68 and preferably opens the bypass channel 74. In the Fig. Figure 6 shows the position of the piston ring 64. In this position, the bypass channel 74 has a second flow cross-section that is larger than the first flow cross-section. The piston ring 64 preferably serves as a throttling element to restrict the flow cross-section of the bypass channel 74.

[0058] The recesses 70 are preferably formed in the radially outwardly projecting circumferential surface of the valve body 58. The valve body 58 has, by way of example, a plurality of recesses 70, which are arranged at uniform intervals around the circumference. The recesses 70 preferably extend axially from the end of the valve body 58 furthest from the piston rod to the shoulder 66 of the valve body 58. By way of example, the recesses 70 are formed in a semi-shell shape with a semicircular cross-section. The recesses preferably have a round, semi-circular, or angular cross-section. In particular, the recesses 70 are all identical.

[0059] The disk 68 preferably has a plurality of cutouts 80 through which the hydraulic fluid can flow. The cutouts 80 are preferably aligned with the recesses 70. In particular, at least some of the cutouts 80 are aligned with the through-bores 60. The bypass channel 74 is preferably formed by the cutouts 80 in the disk 68, the recesses 70 in the valve body 58, and the piston ring 64. The disk 68 is, for example, rotatable about the axial central axis of the auxiliary piston 50, so that the orientation of the cutouts 80 relative to the through-bores 60 and the recesses 70 is adjustable, and thus the flow cross-section is variable.

[0060] The piston ring 64, for example, has a slotted through-hole 76, which represents a complete circumferential interruption of the annular piston ring 64. The piston ring 64 may, by way of example, have a plurality, in particular three, through-holes 76. Preferably, opposing through-holes 76 are identical. For example, the through-hole 76 is formed as a recess in the inner wall and / or the piston rod-side end face of the piston ring 64.

[0061] By way of example, the auxiliary piston 50 has a damping element 28. Preferably, either the auxiliary piston 50 or the piston rod 20 has the damping element 28. The damping element 28 is, in particular, attached to the end face of the auxiliary piston 50 facing the piston rod 20. Preferably, the auxiliary piston has a contact surface 38b that faces the piston rod 20 and is designed to abut the piston rod 20, in particular the contact surface 38a of the piston rod 20. The contact surface 38b preferably forms the end face facing the piston rod 20 and preferably has a recess 32 in which the damping element 28 is arranged. The recess 32 is, by way of example, formed in the connecting element 78. The damping element 28 and the recess 32 correspond to the embodiments described with reference to the recess 32 and the damping element 28 of the piston rod 20.

[0062] The in the Fig. 1 and Fig.The pressure stop receptacle 82 shown in Figure 5 is, by way of example, cylindrical and has a bypass opening 54 that extends through the wall of the pressure stop receptacle 82 and forms a further bypass for hydraulic fluid between the auxiliary piston 50 and the inner wall of the damper tube 14. The bypass opening 54 extends, by way of example, from the piston rod end of the pressure stop receptacle 82 to approximately the axial center of the pressure stop receptacle 82. By way of example, the bypass opening 54 is tapered in the pressure direction, so that the flow cross-section of the bypass opening 54 decreases in the pressure direction. By way of example, the pressure stop receptacle 82 has two bypass openings 54, which are preferably identical. Preferably, the bypass openings 54 are arranged opposite each other, in particular offset from each other by 180° circumferentially.The bypass opening 54 forms a further, in particular a bypass path, through which hydraulic fluid flows from the compression stage working chamber 56 between the auxiliary piston 50 and the inner wall of the damper tube 14. The tapered design of the bypass opening 54 in the pressure direction D ensures, for example, progressive damping of the auxiliary piston in the pressure direction, since the flow cross-section of the bypass path decreases when the auxiliary piston 50 moves in the pressure direction D.

[0063] The pressure stop receptacle 82 comprises, for example, a plurality of connecting arms 40, which are formed at the end region of the pressure stop receptacle 82 furthest from the piston rod and extend in an axial direction. The connecting arms 40 are designed such that they form a positive-locking connection, in particular a snap-fit ​​connection, with the base piece 36. Preferably, the pressure stop receptacle 82 has a plurality of connecting arms 40, which are in particular identical in design and which are arranged at uniform circumferential intervals. The connecting arms 40 are, for example, reversibly deformable outwards in a radial direction, so that the inner diameter of the pressure stop receptacle 82 can be increased. In particular, the connecting arms 40 have a radially inwardly projecting shoulder at their ends furthest from the piston rod.To connect the pressure stop receptacle 82 with the base piece 36, it is pushed onto the base piece 36, whereby the connecting arms 40 are reversibly deformed and form a positive locking connection, in particular a snap lock, with a preferably complementary area to the connecting arms 40 in the base piece 36. Reference symbol list 10 vibration dampers 12 Outer pipe 14 Damper tube / inner tube 16 compensation area 18 working pistons 20 piston rod 21 first piston rod area 22 first workroom 24 second workroom 26 caps 28 damping element 30 Pull stop sleeve 32 recess 34 closure pack 36 bottom piece 38a Plant area 38b Plant area 40 connecting arms 42 Additional piston rod 44 second piston rod area 46 Pull stop 48 Pressure stop arrangement 50 additional pistons 52 spring element 54 Bypass opening in the pressure stop receptacle 56 pressure stage working space 58 valve bodies 60 through holes 62 valve discs 64 piston rings Paragraph 66 68 disc 70 cutouts 74 Bypass channel 76 Passage opening 78 Connecting element 80 excerpts 82 Pressure stop holder Z direction of travel D Pressure direction QUOTES INCLUDED IN THE DESCRIPTION

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

[0000] DE 10 2023 105 059 A1

[0002]

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