CN116255416A - Shock absorber with hydraulic end stop - Google Patents

Abstract

A shock absorber with a hydraulic end stop has: a damper tube radially defining a damper chamber filled with a damper medium; a piston rod axially guided inside the damping chamber; a piston rod guide axially defining a damping chamber, which axially guides the piston rod; a control chamber at one end of the damping chamber; a hydraulic end stop which protrudes into the control chamber in the end travel region of the piston rod and delimits the control chamber axially on one side, so that an axially delimited control chamber is produced therein, the volume of which can be varied as a function of the axial position of the end stop in the control chamber, comprising an end stop ring which is axially fastened to the piston rod; an annular control piston which is movable along the piston rod between a first end stop in the pulling direction and a second end stop in the pressing direction, the end stop ring defining the first end stop, the control piston and the end stop ring forming at least one control channel which ensures a damping medium flow defined between the control chamber and the rest of the control chamber when the control piston is moved into the control chamber.

Description

Shock absorber with hydraulic end stop

Technical Field

The present invention relates to a shock absorber having the features of the preamble of claim 1.

Background

Shock absorbers with hydraulic end stops are known, which are used to adjust the stop stiffness at maximum extension or retraction of the piston rod. The hydraulically acting end stops can absorb high impact energy in extreme road movement conditions. Furthermore, spring-elastic end stops made of elastic material are often used to absorb impact energy.

Document EP 31767664 A1 discloses a hydraulic damping device comprising a conduit filled with a working fluid, a main piston unit movably arranged in the conduit, which main piston unit is fastened to a piston rod which is guided via a sealed guide and divides the conduit into a recoil chamber and a compression chamber. The damping device has an additional at least one travel limiting system arranged at the end of the pipe, which has a constriction with an inlet opening and at least one axial slot, the slot cross-section decreasing from the inlet along the constriction. The damper includes a spring at least partially disposed in the constricted section in the conduit and secured at least one end of the conduit. Furthermore, an additional piston unit is provided, which can be moved together with the main piston unit and is movably placed in the constriction section of the pipe and can be connected to a spring for generating an additional damping force. The piston unit further comprises a molded sleeve distal to the main piston unit, a sealing ring providing a sliding fit for the inner wall surface of the contracted section, and a support sleeve proximal to the main piston unit. The sealing ring surrounds an axial inner ring of the molded sleeve and is axially movable between the support sleeve and an axially outer edge of the molded sleeve. In another aspect, the axial inner race defines at least one axial channel in fluid communication with at least one radial channel defined in the axially outer edge, wherein said inlet of the convergent section has at least one radial slot, preferably extending to said convergent section and connected with at least one of said axial slots.

Disclosure of Invention

The object of the present invention is to provide a damper with a hydraulic end stop, which is characterized by a high operational reliability and a durable construction.

According to the invention, this object is achieved by a shock absorber having the features of claim 1. Advantageous embodiments are given by the dependent claims, the figures and/or the description.

The object of the invention is a shock absorber. In particular, the damper is used and/or adapted to dampen vibrations. The damper is preferably a hydraulic damper. In particular, the shock absorber may be used and/or adapted to the chassis of a vehicle.

The damper has a damper tube radially defining a damper chamber filled with a damper medium. The damper tube is at least partially or completely cylindrical. In principle, the damper has exactly one damper tube. Alternatively, the damper may have two damper tubes that are separated, wherein one damper tube is preferably arranged in the other damper tube. The damping medium is preferably a hydraulic fluid, such as oil.

The damper has a piston rod which is guided axially in a damping chamber. In particular, the damping tube defines a longitudinal axis, wherein the piston rod is guided in the damping tube in an axial direction along the longitudinal axis.

The shock absorber has a piston rod guide for guiding the piston rod in an axial direction, wherein the piston rod guide axially defines a shock absorbing chamber. In particular, the piston rod guide has the function of guiding and/or centring the piston rod when the piston rod moves axially in the shock tube. In particular, the piston rod guide is an end cap which closes the damper tube on the end side in a fluid-tight manner.

The shock absorber preferably has a piston which is connected to the piston rod and divides the damping chamber into a first working chamber and a second working chamber. The first working chamber is arranged between the piston and the piston rod guide, and the second working chamber is arranged on the opposite side of the piston, in particular between the piston and the bottom of the shock absorber. Preferably, the first working chamber is understood to be the working chamber on the piston rod side, while the second working chamber is understood to be the working chamber remote from the piston rod. The two working chambers are at least partially or completely filled with a damping medium. In particular, the piston is connected in a movable manner to the piston rod such that the piston moves together when the piston rod moves in a pulling direction or a pressing direction within the damper tube.

The damper has a control chamber disposed at one end of the damper chamber. In particular, the control chamber is formed axially between the first working chamber and the piston rod guide. Alternatively, however, the control chamber may also be arranged on the opposite side of the piston, between the second working chamber and the shock absorber bottom or bottom valve. The control chamber preferably has a smaller diameter than the first working chamber and/or the second working chamber. In principle, this can be achieved by a diameter reduction or narrowing of the damper tube. Alternatively, the damper has a reduced diameter control sleeve inserted into the damper tube. The control chamber is preferably completely filled with damping medium.

The shock absorber has a hydraulic end stop which protrudes into the control chamber in the end travel region of the piston and delimits the control chamber axially on one side, so that a control chamber is formed in the control chamber, which is preferably delimited axially on the one hand by the piston rod guide and on the other hand by the hydraulic end stop, the volume of which can be varied as a function of the axial position of the hydraulic end stop in the control chamber. In short, the hydraulic end stop is active in the end travel region of the piston and inactive or inactive in the normal travel region of the piston. The end travel region preferably corresponds to the end phase of the pulling phase when the stop is pulled. Alternatively, however, the end travel region may also correspond to the end phase of the pressing phase at the pressing stop. The hydraulic end stop can thus optionally be arranged on the draft side or the compression side of the damper. The hydraulic end stop used as a pull stop is described below.

The hydraulic end stop has an end stop ring axially fixed at the piston rod. The end stop ring is configured circumferentially with respect to the piston rod and/or arranged coaxially with the piston rod. In particular, the end stop ring is arranged within the control chamber.

The hydraulic end stop has an annular control piston which can be displaced along the piston rod between a first end stop in the pulling direction and a second end stop in the pressing direction. In short, the control piston is an annular piston which can be moved axially in a limited manner between two end stops. Here, the end stop ring forms a first end stop in the pulling direction. In particular, an end stop ring is arranged for this purpose in the axial direction between the control piston and the piston rod guide. Thus, when reaching the first end stop in the pulling direction, the end stop ring axially supports the control piston. In the normal travel range, the control piston is preferably arranged at a distance from the inner circumference of the damping tube, so that a radial gap or clearance is formed between the control piston and the damping tube, and the hydraulic end stop is inactive. When the piston is shifted into the end travel region, the control piston preferably protrudes into the control chamber, wherein the control piston delimits the control chamber with respect to the first working chamber or the second working chamber. In this case, the damping medium in the control chamber is compressed, which acts as a hydraulic pillow or pressure pad in the end stop to achieve a hydraulic end stop.

Within the framework of the invention, it is proposed that the control piston forms, together with the end stop ring, one or more control channels which ensure a defined flow of damping medium between the control chamber and the rest of the control chamber when the control piston is moved into the control chamber. In particular, the control channel opens into the control chamber via an access opening, wherein the access opening is delimited in the axial direction, in particular in the pulling direction, by an end stop ring and in the axially opposite direction, in particular in the pressing direction, by the control piston. In particular, the control chamber and the rest of the control chamber are fluidically connected to each other via a control channel. When the piston rod is moved in the pulling direction in the end stroke region, the throttled volume flow preferably flows from the control chamber into the remainder of the control chamber via the control channel. When the piston rod is moved in the direction of extrusion in the end stroke region, the released volume flow preferably flows from the control chamber into the control chamber via the control channel. The control channel preferably cooperates with the end stop ring such that the flow resistance of the control channel decreases when the control piston moves in the direction of the first end stop and/or increases when the control piston moves in the direction of the second end stop. The damping force generated by the hydraulic end stop thereby increases during the movement of the piston rod in the end stroke region, in particular in the pulling direction, and decreases during the return stroke, in particular in the pressing direction.

The advantage of the invention is in particular that the control piston can be designed particularly durable and cost-effectively by the effective connection of the control piston to the end stop ring. Furthermore, a hydraulic end stop is proposed, which is characterized by a reduced number of components compared to the prior art. Furthermore, the arrangement according to the invention ensures that in the case of a mechanical end stop of the piston rod, the force transmission path is transferred directly into the piston rod via the end stop ring, so that the mechanical loading of the hydraulic end stop, in particular of the control piston, is avoided. As a result, the operational safety of the hydraulic end stop can be additionally improved.

In a specific embodiment, it is provided that the control piston has a plurality of axially projecting webs on its side facing the end stop ring, by means of which webs the control piston can be supported on the end stop ring. In particular, the stack extends in the axial direction, in particular in the pulling direction, starting from the first axial end face of the control piston. For the hydraulic flow through the stacks, a recess is provided between the stacks, through which recess the control channel opens into the control chamber. In particular, the stacks are evenly spaced apart from one another in the circumferential direction over the free area. Preferably, the access openings of the control channels are each defined by one of the empty areas. In the circumferential direction, the access opening is thus defined or delimited by every two adjacent stacks. The control piston is particularly preferably supported in the first end stop by a stack on the end stop ring, wherein the volume flow between the control chamber and the rest of the control chamber is ensured by the free area. Thus, a control piston is proposed, which is characterized by a simple structure and a durable design.

In a further embodiment, it is provided that the recess is formed as a window between two stacks, the window being at least as large as one of the stacks. In this way, the free area can ensure even circulation through the stack.

In a further embodiment, it is provided that the end stop ring has a narrowing section, by means of which the end stop ring is fixed to the piston rod in a form-fitting and/or force-fitting manner. In particular, the narrowing section has a cross-sectional profile which converges in the extrusion direction, in particular in the form of a cone, as seen in cross-section. The narrowing section is preferably accommodated in an axially fixed manner in an annular groove formed at the piston rod. The stack has an inclined surface on its radially inner side which is complementary to the narrowed section. In particular, the inclined surface and the narrowing section are identically oriented and/or aligned substantially parallel to each other. More specifically, the narrowing section and the inclined surface may be aligned with each other with an angular deviation of more than 1 degree, preferably more than 5 degrees, in particular more than 10 degrees. When the control piston moves axially between the two end stops, the control piston can be guided and/or centered at the narrowing section by the inclined surface. This prevents the control piston from wedging into the annular space and thus improves the operational safety of the shock absorber.

In a further embodiment, it is provided that the control piston has a circumferential piston outer surface which bears against the inner periphery of the control chamber in the radial direction. In particular, the outer side of the piston is the outer surface of the cylinder liner of the control piston, also called piston skirt. The control piston preferably bears against the inner periphery of the control chamber in a piston outer side, preferably in a circumferential sealing manner. At least one control channel opens out of the outer side of the piston into an annular gap formed radially between the inner periphery of the control chamber and the control piston. In particular, "outside the piston outer side" means that the control channel enters or exits spaced apart from and/or adjacent to and/or offset from the piston outer side. The annular gap is preferably formed radially inside the control chamber between the radially outer side of the control piston, in particular the stack, and the inner periphery of the control chamber, in particular the control sleeve. In other words, the annular gap is formed by the radial distance between the control piston and the inner periphery of the control chamber. In the axial direction, in particular in the pressing direction, the annular gap is delimited by the abutment of the outer side of the piston on the inner periphery of the control chamber. A control piston is therefore proposed, which ensures a reliable flow of damping medium through the control channel, in particular in the pull-off stop.

In a further embodiment, it is provided that the end stop ring has a first stop surface on its side facing the control piston, which first stop surface defines the first end stop. The first stop surface is preferably formed by an annular surface extending about the longitudinal axis, on which the stack is supported at the end side when reaching the first end stop in the pulling direction. The first stop surface preferably extends in a radial plane of the longitudinal axis. The first stop surface is preferably formed by a radial step or annular shoulder on the end stop ring. In particular, the narrowing section directly adjoins the first stop surface in the axial direction, in particular in the pressing direction. A control piston is therefore proposed, which is characterized by a reliable arrangement at the end stop.

In a further embodiment, it is provided that the control channel has a first channel section and a second channel section, wherein the first channel section connects the control chamber on the control chamber side to the inner side of the control piston, and the second channel section connects the control chamber on the side facing away from the control chamber to the inner side of the control piston. In other words, the first channel section opens into the control chamber interior, while the second channel section opens out of the control chamber. Here, a third channel section is formed between the inner side and the piston rod, wherein the third channel section connects the first channel section and the second channel section to each other. The first channel section and/or the second channel section preferably extend radially and/or transversely to the longitudinal axis. The third channel section preferably extends parallel to the longitudinal axis and/or in the same direction. In particular, the control piston has a plurality of first and/or second channel sections. In principle, the first channel section and the second channel section can each form a separate control channel, wherein the plurality of control channels are fluidically separated from one another and/or hydraulically parallel in the control piston. For this purpose, the first channel sections are each connected to the associated second channel section by a separate third channel section. Alternatively, a plurality of first channel sections and/or second channel sections may together form a control channel. For this purpose, the plurality of first channel sections and/or second channel sections are connected to one another by a common third channel section. The size and/or number of the first channel section and/or the second channel section may be varied depending on the required end stop force.

In a further embodiment, it is provided that the first channel section is located between the stacks. The first channel section can be formed between the stacks in such a way that its free opening cross section is defined and/or limited by the end stop ring. In other words, at least the first channel section is formed between the end stop ring and the control piston. The first channel section is preferably formed by an empty region between the stacks. Furthermore, the second channel section is preferably integrated into the second axial end face of the control piston, so that the free opening cross section of the second channel section expands when the control piston is lifted from the second end stop. In particular, the second channel section may be formed by a recess, a notch or the like introduced in the second axial end face. A control piston is therefore proposed, which is characterized by a simple and inexpensive production.

In a further embodiment, it is provided that the control piston is produced in one piece from a material section. In particular, the control piston may be made of a single casting and/or of a solid material, for example by milling, cutting or the like. The control piston is preferably made of plastic. A control piston is therefore proposed, which is characterized by a durable construction and is also easy to manufacture.

In a further development, it is provided that the shock absorber has a support ring which is axially fixed to the piston rod, wherein the support ring defines the second end stop. In particular, the control piston can be supported with a stack at the end stop ring in the pulling direction and can be supported with a second axial end face on the support ring in the pressing direction. The support ring preferably has a second stop surface defining a second end stop. The second stop surface is preferably formed by an annular surface extending around the longitudinal axis, against which the control piston rests in a surface-wise and/or planar manner with the second end surface when the first end stop is reached in the pressing direction. The second stop surface preferably extends in the same direction and/or parallel to the first stop surface in a radial plane of the longitudinal axis. In principle, the support ring may be a slotted ring, in particular a snap ring. Alternatively, however, the support ring may also be a solid part which is at least indirectly connected to the piston rod or which is supported at the piston rod. The support ring may be one-piece or multi-piece, in particular two-piece. A hydraulic end stop is therefore proposed, which is characterized by a simple assembly and a low-cost design.

In a first possible embodiment, the support ring is connected to the piston rod in a force-transmitting and/or material-transmitting manner in the axial direction. For this purpose, the support ring can be fixed to the piston rod in a force-transmitting manner by means of self-locking and/or perforation and/or by means of a press fit, either singly or in multiple. Alternatively or additionally, the support ring may be fixed to the piston rod in a material-connecting manner by means of one or more weld and/or weld spots, for example by means of laser welding. A hydraulic end stop is thus provided, which is characterized by a particularly durable assembly and a reduced number of parts.

In an alternative embodiment, the damper has a stop ring which is axially fixed at the piston rod. Wherein the support ring is supported at the piston rod in the extrusion direction by means of a stop ring. In particular, the stop ring is a slotted ring, in particular a snap ring. The stop ring can be mounted in a form-fitting manner in a corresponding stop ring groove on the piston rod. The support ring is preferably a solid member. Due to the form-fitting assembly of the support ring, tolerances can be compensated for and the end jump (Planlauf) of the second end stop can also be improved.

In a further development, it is provided that the support ring has a receiving section for and/or adapted to receive the retaining ring in a form-fitting manner. In particular, the receiving section is an annular groove complementary to the blocking ring, in which the blocking ring is received at least in an axially and/or radially positive-locking and/or precisely-locking manner. The receiving section is particularly preferably formed by a cylindrical depression formed at the inner diameter. A support ring is therefore proposed, which is characterized by a particularly stable seat.

In a further embodiment, it is provided that the damper has an end stop damper which is arranged axially between the end stop ring and the piston rod guide. In particular, the end stop buffer forms a mechanical end stop in the pulling direction of the piston rod. For this purpose, the end stop damper is preferably supported at the end stop ring in the pressing direction. The end stop damper is preferably cylindrical or sleeve-shaped. In particular, the end stop buffer is made of an elastically deformable material, preferably rubber. The end stop buffer thus prevents the end stop ring from directly abutting the piston rod guide in the limit travel range. The end stop ring preferably directs the stop force acting on the end stop damper directly into the piston rod. In other words, the force travel extends from the end stop buffer through the end stop ring to the piston rod, wherein the control piston is arranged outside the force transmission path. The control piston can thus be designed in a particularly simple manner, for example made of plastic.

Drawings

Additional features, advantages and effects of the present invention will be made apparent from the following description of the preferred embodiments of the present invention. Here, it is shown that:

FIG. 1 shows a schematic cross-sectional view of a shock absorber with a hydraulic end stop as an embodiment of the present invention;

fig. 2 shows a schematic cross-section of the hydraulic end stop according to fig. 1.

Detailed Description

Fig. 1 shows in a highly schematic illustration a shock absorber 1, which is suitable for example for a vehicle wheel suspension. The damper 1 is a monotube damper and for this purpose has a cylindrical damper tube 2 which delimits a damper chamber 3 filled with a damping medium in the radial direction. Alternatively, however, the vibration damper 1 may also be a double tube vibration damper, wherein the vibration damper tube 2 is accommodated for this purpose in a further vibration damper tube, not shown.

The shock absorber 1 has a piston rod 4 and a piston 5, which is connected at its end to the piston rod 4 and is shown schematically, which is guided in the shock tube 2 movably along a longitudinal axis L. For this purpose, the piston rod 4 is guided axially in the axial direction by a piston rod guide 6, wherein the piston rod guide 6 at the same time delimits the damping chamber 3 in the pulling direction Z. Furthermore, the piston 5 is guided axially on the inner wall surface of the damper tube 2.

The damping chamber 3 is divided by the piston 5 into a first working chamber 7, in particular a working chamber close to the piston rod, and a second working chamber 8, in particular a working chamber remote from the piston rod. Here, a first working chamber 7 is formed axially between the piston 5 and the piston rod guide 6, and a second working chamber 8 is formed axially between the piston 5 and a damper base (not shown). The two working chambers 7, 8 are completely filled with a damping medium, for example oil.

The shock absorber 1 also has a hydraulic end stop 9, which in the embodiment shown is a pull stop and limits the maximum extension of the piston rod 4 in the pull direction Z. It should be pointed out in advance that a design as a compression stop is also possible.

The shock absorber 1 has a control sleeve 10 which is inserted into the shock tube 2 and defines a control chamber 11 in the radial direction. The control chamber 11 is arranged axially between the first working chamber 7 and the piston rod guide 6 and has a smaller effective diameter than the first working chamber 7. The diameter difference is determined here by the wall thickness of the control sleeve 10. For example, the control sleeve 10 is pressed into the damper tube 2.

The hydraulic end stop 9 comprises an end stop ring 12 and a control piston 13, which are mounted coaxially on the piston rod 4 with respect to the longitudinal axis L. The end stop ring 12 surrounds the piston rod 4 and is fixed to the piston rod 4 in a force-fitting, in particular axially fixed manner. The end stop ring 12 is arranged axially between the control piston 13 and the piston rod guide 6 and serves to support the control piston 13 in the pulling direction Z. For example, the end stop ring 12 is pressed into a circumferential annular groove formed on the piston rod 4. The control piston 13 is an annular piston surrounding the piston rod 4, which is supported on the piston rod 4 in a sliding manner in the axial direction.

During the pulling phase, the hydraulic end stop 9 protrudes in the pulling direction Z from a defined travel position, in particular in the end travel region, into the control sleeve 10, and in this case defines a control chamber 14 formed between the piston rod guide 6 and the control piston 13. The volume of the control chamber 14 can be varied depending on the axial position of the hydraulic end stop 9 in the control sleeve 10. The end travel region corresponds here to the end phase of the pulling phase at the pulling stop. The control sleeve 10 has a constant inner diameter which corresponds to the insertion diameter of the control piston 13. The insertion diameter is defined here by a piston outer surface 15 of the control piston 13, by means of which piston outer surface the control piston 13, when it protrudes into the control chamber 11, radially rests against the inner circumference of the control sleeve 10 and thus seals the control chamber 14 at least in part.

Furthermore, the shock absorber 1 has a resilient end stop damper 16, which may alternatively be designed as a coil spring, wherein the end stop damper is arranged in the axial direction between the end stop ring 12 and the piston rod guide 6. When the piston rod 4 is completely moved out of the damper tube 2 in the pulling direction Z, the end stop damper serves as a mechanical end stop, wherein the stop force is transmitted into the piston rod 4 via the end stop ring 12. In order to reduce the stop noise generated here, the end stop damper 16 is generally made of an elastic plastic or rubber.

The control piston 13 is limitedly movable along the piston rod 4 between a first end stop 17 and a second end stop 18. In the embodiment shown, the first end stop 17 is defined by the end stop ring 12 in the pulling direction Z and the second end stop 18 is defined by the support ring 22 in the pressing direction D. The control piston 13 can be supported on the first end stop 17 in the pulling direction Z when the piston rod 4 is in a squeezing movement, and the control piston 13 can be supported on the second end stop 18 in the squeezing direction D when the piston rod 4 is in a pulling movement.

The control piston 13 is produced in one piece from a material section 19. For example, the control piston 13 is made of a casting, such as plastic injection casting. The control piston 13 can thus be produced particularly easily and cost-effectively.

The end stop ring 12 has a first stop surface 20 defining a first end stop 17. The first stop surface 20 is here an annular surface about the longitudinal axis, which is formed by an annular shoulder formed at the end stop ring 12. Conversely, the support ring 22 defines the second end stop 18 with the second stop surface 21 in the pressing direction D. The first stop surface 20 and the second stop surface 21 each extend in a radial plane of the longitudinal axis L or are designed as two opposite surfaces aligned parallel to each other.

The support ring 22 is supported at the piston rod 4 in the pressing direction D by a stop ring 23. The stop ring 23 is, for example, a snap ring which is mounted in a form-fitting manner in a stop ring groove, in particular in an annular groove, at the outer circumference of the piston rod. The support ring 22 is a solid part and has at its inner diameter a receiving section 24 which receives the stop ring 23. The receiving section 24 is formed, for example, by a cylindrical depression in which the stop ring 23 is received in a form-fitting manner in the radial direction and at least in the pulling direction Z.

Furthermore, a plurality of control channels 25 are formed between the end stop ring 12 and the control piston 13, which control channels allow, in particular during the pulling phase, a damping medium flow defined between the control chamber 14 and the rest of the control chamber 11. When the piston rod 4 moves in the normal travel range, a radial distance exists between the piston outer surface 15 and the damping tube 2, so that the damping medium flows outside past the hydraulic end stop 9 and the latter is deactivated. With a greater stroke movement of the piston rod 4 in the end stroke region, the control channel 25 acts such that damping medium can flow through the control channel 25 from the control chamber 14 into the remainder of the control chamber 11 during a pulling movement and from the control chamber 11 into the control chamber 14 during a pressing movement. During the pulling movement, the control piston 13 rests against the support ring 22, wherein the volume flow of the damping medium is throttled, so that the hydraulic end stop 9 generates an additional damping force which increases to the damping force of the piston 5. During the pressing movement, the control piston 13 lifts off the support ring 22, wherein the volumetric flow of the damping medium is released, so that the hydraulic end stop 9 creates a pressure equalization between the control chamber 11 and the control chamber 14.

The size and/or number of control channels 25 depends on the desired end stop force. The control channel 25 opens out of the piston outer surface 15 into an annular gap 26 formed radially between the control piston 13 and the control sleeve 10, to the control chamber 14. For example, when the end stop damper 16 is deformed, the annular gap 26 ensures a volumetric flow of the damping medium, as a result of which the operational safety of the damper 1 can be significantly improved.

Fig. 2 shows the hydraulic end stop 9 as already described in fig. 1 in a perspective sectional view. The control piston 13 has a plurality of stacks 27 extending in the pulling direction Z, which are each uniformly spaced apart from one another in the circumferential direction along the recess 28. The hollow region 28 is a window-shaped recess and at the same time defines the passage openings of the flow channels 25, through which the flow channels open into the annular gap 26. The stack 27 here extends from a first axial end face 29 of the control piston 13 in the direction of the first stop face 20. When reaching the first end stop 15, the control piston 13 is thus supported at the end by the stack 27 in the pulling direction Z at the first stop surface 20.

The end stop ring 12 has a narrowing section 30 by means of which the end stop ring 12 is fixed to the piston rod 4 in a form-fitting and/or force-transmitting manner, in particular to an annular groove. The narrowing section 30 here directly adjoins the first stop surface 20 in the pressing direction. The narrowing section 30 has a cross-sectional profile which converges or tapers in the pressing direction D, as seen in cross-section. The narrowing section 30 thus achieves self-locking in the pressing direction D, so that high mechanical stop forces can be transmitted into the piston rod 4 via the end stop ring 12.

The stack portions 27 each have an inclined surface 31 on the radially inner side thereof, which is aligned in the same direction as the outer peripheral edge of the narrowed section 30. The control piston 13 can slide in the axial direction over the narrowing section 30 by means of a ramp 31. Here, the inclined surface 31 serves to guide and/or centre the control piston 13 during axial movement, in order to prevent the control piston 13 from wedging into the control sleeve 10.

The control passage 25 is formed by a first passage section 32, a second passage section 33, and a third passage section 34, respectively. The first channel section 32 opens into the control chamber 14, wherein the first channel section 32 connects the control chamber 14 with an inner side surface 35 of the control piston 13. For this purpose, the first channel sections 32 are formed between the stacks 31 by the free areas 28. The first channel section 32 is thus delimited or defined in the circumferential direction by the stack 27 and in the axial direction by the end stop ring 12, in particular by the first stop surface 20 and the narrowing section 30, on the one hand, and by the first axial end surface 29, on the other hand.

The second channel section 33 opens into the control chamber 11 on the side facing away from the control chamber 14, wherein the second channel section 33 connects the remaining part of the control chamber 11 with an inner side surface 35 of the control piston 13. The second channel section 33 is a recess, in particular a throttle groove, which is introduced into the second axial end face 36 of the control piston 13. In this case, the control piston 13 rests in the second end stop 18 via the second axial end face 36 against the second stop face 21 over the entire surface or in a planar manner, wherein the free opening cross section of the flow channel 25, in particular of the second channel section 33, increases or reduces the flow resistance when the control piston 13 is lifted off the end stop ring 12.

The third channel section 34 is formed between the piston rod 4 and the inner side surface 35 and connects the first channel section 32 and the second channel section 33 to each other. The third channel section 30 is formed here by a gap formed between the piston rod 4 and the inner side surface 31, which gap is delimited in the pulling direction Z by the end stop ring 12 and in the pressing direction D by the support ring 22. The channel section 34 may for example be defined over its radial extension by a spacer element (not shown here), such as a web, a cam or the like, extending radially between the piston rod 4 and the inner side surface 35 of the control piston 13. The spacer element simplifies the centering guidance of the control piston 13 at the piston rod 4.

In order to make it easier for the control piston 13 to protrude into the control sleeve 10, the control piston 13 also has an entry surface 37, which may be formed by a circumferential radius or a circumferential chamfer. The entry surface 37 connects the piston outer surface 15 to the first axial end surface 29, wherein the annular gap 26 is delimited in the pressing direction by the entry surface 37, as is depicted in fig. 1.

List of reference numerals

1 vibration damper

2 vibration damping tube

3 vibration damping chamber

4 piston rod

5. Piston

6. Piston rod guide

7. First working chamber

8. Second working chamber

9. Hydraulic end stop

10. Control sleeve

11. Control room

12. End stop ring

13. Control piston

14. Control chamber

15. Outer side of piston

16. End stop buffer

17. First end stop

18. Second end stop

19. Material section

20. A first stop surface

21. Second stop surface

22. Support ring

23. Baffle ring

24. Receiving section

25. Control channel

26. Annular gap

27. Stack part

28. Empty area

29. First end surface

30. Narrowing section

31. Inclined surface

32. A first channel section

33. A second channel section

34. Third channel section

35. Inside surface

36. Second end face

37. Entry face

D extrusion direction

L longitudinal axis

Z the pulling direction.

Claims (15)

1. A shock absorber (1) having:

a damping tube (2) radially defining a damping chamber (3) filled with a damping medium;

-a piston rod (4) axially guided within the damping chamber (3);

-a piston rod guide (6) axially defining the damping chamber (3), wherein the piston rod (4) is guided in an axial direction by the piston rod guide (6);

a control chamber (11) arranged at one end of the damping chamber (3),

a hydraulic end stop (9) which protrudes into the control chamber (11) in the end travel region of the piston rod (4) and delimits the control chamber axially on one side such that an axially delimited control chamber (14) is formed in the control chamber (11), the volume of which can be varied as a function of the axial position of the end stop (9) in the control chamber (11), comprising:

an end stop ring (12) axially fixed at the piston rod (4),

an annular control piston (13) which can be moved along the piston rod (4) between a first end stop (17) in the pulling direction (Z) and a second end stop (18) in the pressing direction (D), wherein the end stop ring (12) defines a first end stop (17),

it is characterized in that the method comprises the steps of,

the control piston (13) forms together with the end stop ring (12) at least one control channel (25) which ensures a defined damping medium flow between the control chamber (14) and the rest of the control chamber (11) when the control piston (13) is moved into the control chamber (11).

2. Shock absorber (1) according to claim 1, characterized in that the control piston (13) has a plurality of axially protruding stacks (27) on its side facing the end stop ring (12), by means of which stacks the control piston (13) can be supported on the end stop ring (12), wherein for hydraulic throughflow of the stacks (27) a free area (28) is formed between the stacks (27), through which the at least one control channel (25) leads to the control chamber (14).

3. Shock absorber (1) according to claim 2, wherein said empty areas (28) are each formed by a window-like recess corresponding to at least one of the dimensions of said stacks (27).

4. A shock absorber (1) according to claim 2 or 3, characterized in that the end stop ring (12) has a narrowing section (30) by means of which the end stop ring (12) is fixed in a form-fitting and/or force-transmitting connection, wherein the stack (27) has an inclined face (31) at the radially inner side, which is complementary to the narrowing section (30).

5. The shock absorber (1) according to any of the preceding claims, wherein the control piston (13) has a circumferential piston outer side (15) which abuts against an inner periphery of the control chamber (11) in a radial direction, wherein the at least one control channel (25) opens out of the piston outer side (15) into an annular gap (25) formed radially between the inner periphery of the control chamber (11) and the control piston (13).

6. The shock absorber (1) according to any of the preceding claims, wherein the end stop ring (12) has a first stop surface (20) at its side facing the control piston (13), the first stop surface defining a first end stop (17).

7. Shock absorber (1) according to claim 6, wherein the control piston (13) can be supported at the end side by means of the stack (27) at the first stop surface (20).

8. The shock absorber (1) according to any of the preceding claims, wherein the at least one control conduit (25) has: -a first channel section (32) connected on one side of the control chamber (14) to an inner side (35) of the control piston (13) and the control chamber (11); and a second channel section (33) which connects the control chamber (11) to an inner side (35) of the control piston (13) on a side facing away from the control chamber (14), wherein a third channel section (34) is formed between the inner side (35) and the piston rod (4) and connects the first section (32) and the second channel section (33) to each other.

9. The shock absorber (1) according to claim 8, wherein the first channel section (32) is formed between the stacks (27).

10. Shock absorber (1) according to any of the preceding claims, wherein the control piston (13) is integrally made of a material section (19).

11. Shock absorber (1) according to any of the preceding claims, characterized by a support ring (22) axially fixed on the piston rod (4), wherein the support ring (22) defines the second end stop (18).

12. Shock absorber (1) according to claim 11, wherein the support ring (22) is connected to the piston rod (4) in a force-transmitting and/or material-transmitting manner in the axial direction.

13. Shock absorber (1) according to claim 11, having a stop ring (23) axially fixed at the piston rod (4), wherein the support ring (22) is supported at the piston rod (4) in the extrusion direction (D) by the stop ring (23).

14. The shock absorber (1) according to any of claims 11 to 13, wherein the support ring (22) has a receiving section (24) in which the stop ring (23) is received in a form-fitting manner.

15. Shock absorber (1) according to any of the preceding claims, having an end stop bumper (16) arranged axially between the end stop ring (12) and the piston rod guide (6), wherein the end stop bumper (16) is supported at the end stop ring (12) in the direction of compression (D).

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