CN116255416A - Shock absorbers with hydraulic end stops - 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 absorbers with hydraulic end stops

technical field

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

Background technique

Vibration dampers with hydraulic end stops are known, which serve to adjust the stop hardness at maximum extension or retraction of the piston rod. The hydraulically acting end stops are here able to absorb high impact energies under extreme road movement conditions. Furthermore, generally spring-elastic end stops made of elastic material are used to absorb impact energy.

Document EP 3176464 A1 discloses a hydraulic buffer device comprising a pipe filled with working fluid, a main piston unit movably arranged in the pipe, the main piston unit is fastened to a piston rod, the piston rod It is guided via a sealed guide and divides the pipe into a recoil chamber and a compression chamber. The damping device has an additional at least one stroke limiting system arranged at the end of the duct, the stroke limiting system having a converging section with an inlet opening and at least one axial groove whose cross-section narrows from the inlet along Sections get smaller. The shock absorber includes a spring at least partially placed in a constricted section in the duct and fastened at at least one end of the duct. Furthermore, an additional piston unit is provided, which is movable together with the main piston unit and which is displaceably placed in the constriction of the duct and which can be connected to a spring to generate an additional damping force. The piston unit also includes a molded sleeve remote from the main piston unit, a seal ring providing a sliding fit to the inner wall surface of the constricted section, and a bearing sleeve adjacent to the main piston unit. A sealing ring surrounds the axially inner ring of the molding sleeve and is axially movable between the support sleeve and the axially outer edge of the molding sleeve. In another aspect, the axially inner race defines at least one axial passage in fluid communication with at least one radial passage defined in the axially outer edge, wherein said inlet of the constricted section has at least one radial The radial groove preferably extends to said constriction section and is connected to at least one of said axial grooves.

Contents of the invention

It is an object of the present invention to provide a shock absorber with a hydraulic end stop which is characterized by high operating reliability and a durable construction.

This object is achieved according to the invention by a shock absorber having the features of claim 1 . Advantageous refinements are given by the subclaims, the figures and/or the description.

The object of the invention is a shock absorber. In particular, the vibration damper is used and/or suitable for damping vibrations. The shock absorber is preferably a hydraulic shock absorber. In particular, the shock absorber can be used and/or adapted for a chassis of a vehicle.

The shock absorber has a damping tube radially delimiting a damping chamber filled with a damping medium. The damper tube is at least partially or completely cylindrical. In principle, the shock absorber has exactly one damper tube. Alternatively, the shock absorber can have two separate damper tubes, wherein one damper tube is preferably arranged in the other damper tube. The damping medium is preferably a hydraulic fluid, such as oil.

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

The shock absorber has a piston rod guide for guiding the piston rod in the axial direction, wherein the piston rod guide axially delimits a damping chamber. In particular, the piston rod guide has the function of guiding and/or centering the piston rod when it moves axially within the damper tube. In particular, the piston rod guide is an end cap which closes the damper tube at the end in a fluid-tight manner.

The damper 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 shock absorber bottom. Preferably, the first working chamber is understood to be the working chamber on the piston rod side, and 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 kinematically connected to the piston rod such that when the piston rod moves in the pulling or squeezing direction within the damper tube, the piston moves together.

The shock absorber has a control chamber arranged at one end of the shock absorber chamber. In particular, a control chamber is formed axially between the first working chamber and the piston rod guide. Alternatively, however, the control chamber can 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 reducing or narrowing the diameter of the damper tube. Alternatively, the shock absorber has a reduced diameter control sleeve inserted into the shock absorber 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 area of the end stroke of the piston and delimits it axially on one side, so that in the control chamber A control chamber is formed in the middle, preferably axially delimited by the piston rod guide on the one hand and by a hydraulic end stop on the other hand, the volume of which can be controlled according to the hydraulic end stop The axial position of the stopper in the control chamber changes. In simple terms, hydraulic end stops work in the piston's end travel region and are inactive or nonfunctional in the piston's normal travel region. The end travel range here preferably corresponds to the end phase of the pulling phase when the pulling stop is pulled. Alternatively, however, the end stroke range can also correspond to the end phase of the pressing phase when pressing against the stop. The hydraulic end stop can thus optionally be arranged on the draft side or the compression side of the shock absorber. The hydraulic end stops used as pull stops are described below.

The hydraulic end stop has an end stop ring which is fixed axially on the piston rod. The end stop ring is designed circumferentially relative to the piston rod and/or is arranged coaxially with the piston rod. In particular, an end stop ring is arranged in the control chamber.

The hydraulic end stop has an annular control piston that can move 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 is axially displaceable in a limited manner between two end stops. Here, the end stop ring forms a first end stop in the pulling direction. In particular, the end stop ring is arranged for this purpose in the axial direction between the control piston and the piston rod guide. Thus, the end stop ring supports the control piston axially when the first end stop is reached in the pulling direction. In the normal travel range, the control piston is preferably arranged at a distance from the inner circumference of the damper tube, so that a radial gap or spacing is formed between the control piston and the damper tube, and hydraulic end stops are ineffective of. When the piston transitions into the end stroke range, 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. Here, the damping medium in the control chamber is compressed, which acts as a hydraulic pillow or pressure pad in the end stop in order to realize a hydraulic end stop.

It is proposed within the framework of the invention that the control piston together with the end stop ring form one or more control channels, which ensure a communication between the control chamber and the rest of the control chamber when the control piston moves into the control chamber. Defined damping medium flow. In particular, the control channel opens into the control chamber via an opening, wherein the opening is limited in the axial direction, in particular in the pulling direction, by the end stop ring, and in the opposite axial direction, in particular In the extrusion direction it is limited 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 moves in the pulling direction in the end stroke region, a throttled volume flow flows from the control chamber into the remainder of the control chamber, preferably via the control channel. When the piston rod moves in the extrusion direction in the end stroke region, the released volume flow flows from the control chamber into the control chamber, preferably via the control channel. The control channel preferably cooperates with the end stop ring such that when the control piston moves in the direction of the first end stop, the flow resistance of the control channel decreases and/or when the control piston moves towards the second end stop When moving in the direction of the component, the flow resistance of the control channel increases. As a result, the damping force generated by the hydraulic end stop 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. Small.

The advantage of the invention is in particular that the operative connection of the control piston to the end stop ring enables a particularly durable and cost-effective design of the control piston. Furthermore, a hydraulic end stop is proposed, which is characterized by a reduced number of parts 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 via the end stop ring into the piston rod, so that hydraulic end stops are avoided. The mechanical load, especially the mechanical load of the control piston. As a result, the operational safety of the hydraulic end stop can be additionally improved.

In a specific refinement it is provided that the control piston has, on its side facing the end stop ring, a plurality of axially protruding stacks, by means of which the control piston can be supported on the end stop ring. In particular, the stack extends from the first axial end face of the control piston in the axial direction, in particular in the pulling direction. For the hydraulic flow through the stacks, free areas are formed between the stacks, through which free areas the control channel leads to the control chamber. In particular, the stacks are evenly spaced from one another in the peripheral direction over the free area. Preferably, the access openings of the control channels are respectively defined by one of the empty areas. In the peripheral direction, the access opening is thus delimited or delimited by every two adjacent stacks. The control piston is particularly preferably supported in the first end stop on the end stop ring via a stack, wherein a volume flow between the control chamber and the rest of the control chamber is ensured by the free area. Therefore, a control piston is proposed which is characterized by a simple construction and a robust design.

In another embodiment, it is provided that the free area is formed in each case as a window between two stacks which is at least as large as one of the stacks. As a result, the free area can ensure a uniform flow through the stack.

In another embodiment, it is provided that the end stop ring has a narrowed section by means of which the end stop ring is fastened to the piston rod in a form-fitting and/or non-positive connection. In particular, viewed in cross section, the narrowing section has a converging, in particular conical, cross-sectional course in the extrusion direction. The narrowing section is preferably accommodated in an axially fixed manner in an annular groove formed at the piston rod. On its radial inner side, the stack has an inclined surface complementary to the narrowing section. In particular, the bevel and the constriction are oriented identically and/or aligned substantially parallel to one another. More specifically, the narrowing section and the inclined face can be aligned with each other with an angular offset of more than 1 degree, preferably more than 5 degrees, in particular more than 10 degrees. When the control piston is displaced axially between the two end stops, the control piston can be guided and/or centered at the narrowing section by the inclined surface. Wedging of the control piston in the annular space can thus be prevented and thus the operational reliability of the shock absorber can be improved.

In a further embodiment, it is provided that the control piston has a peripheral piston outer side which rests in radial direction on the inner circumference of the control chamber. In particular, the outer side of the piston is the outer surface of the cylinder liner of the control piston, also called the piston skirt. The control piston preferably bears against the inner circumference of the control chamber with the piston outer side, preferably in a circumferentially sealing manner. At least one control channel opens outside the outer side of the piston to an annular gap formed radially between the inner periphery of the control chamber and the control piston. In particular, "outside the outer side of the piston" means that the control channel enters or exits at a distance from and/or adjacent to and/or offset from the outer side of the piston. An annular gap is preferably formed radially within the control chamber between the control piston, in particular the radial outer side of the stack, and the inner circumference 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 circumference 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 circumference of the control chamber. A control piston is thus proposed which ensures a reliable flow of damping medium through the control channel, in particular in the pull stop.

In another constructive refinement, it is provided that the end stop ring has a first stop surface on its side facing the control piston, which first limit stop defines the first end stop. The first stop surface is preferably formed by an annular surface extending around the longitudinal axis, on which the stack is supported at the end side when the first end stop is reached 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 extrusion direction. A control piston is therefore proposed which is characterized by a secure seating on the end stop.

In another 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 The section connects the control chamber on the side facing away from the control chamber with the inner side of the control piston. In other words, the first channel section leads to the interior of the control chamber and the second channel section leads to the outside of the control chamber. In this case, 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 one another. 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 and/or in the same direction as the longitudinal axis. 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. To this end, the first channel section is connected to the associated second channel section in each case via a separate third channel section. Alternatively, a plurality of first channel sections and/or second channel sections can together form a control channel. For this purpose, a plurality of first channel sections and/or second channel sections are connected to one another via a common third channel section. The size and/or number of the first channel section and/or the second channel section can vary depending on the required end stop force.

In another 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 limited and/or limited by the end stop ring. In other words, at least a first channel section is formed between the end stop ring and the control piston. The first channel section is preferably formed by empty areas 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 can be formed by a recess, recess, recess or the like introduced in the second axial end face. A control piston is thus proposed which is characterized by simple and cost-effective production.

Provision is made in another embodiment for the control piston to be produced in one piece from a material section. In particular, the control piston can be produced from a single casting and/or from solid material, eg by milling, cutting or the like. The control piston is preferably made of plastic. A control piston is therefore proposed which is distinguished by a durable construction and which is also easy to manufacture.

In another refinement, it is provided that the vibration absorber has a support ring which is fixed axially on the piston rod, wherein the support ring defines the second end stop. In particular, the control piston can be supported with a stack on the end stop ring in the pulling direction and can be supported at the support ring with the second axial end face 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 surface-to-surface and/or planarly with the second end surface when the first end stop is reached in the extrusion direction. ring surface. 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 can be a groove ring, in particular a snap ring. Alternatively, however, the support ring can also be a solid part which is at least indirectly connected to the piston rod or supported on the piston rod. The support ring can be one-piece or multi-part, in particular two-part. A hydraulic end stop is thus proposed which is characterized by simple assembly and a cost-effective design.

In a first possible embodiment, the support ring is non-positively and/or materially connected to the piston rod in the axial direction. For this purpose, the support ring can be attached to the piston rod monolithically or multiply in a non-positive manner by self-locking and/or perforation and/or by force-fitting. Alternatively or optionally additionally, the support ring can be fixed to the piston rod in a materially bonded manner by one or more weld seams and/or weld spots, for example by 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 shock absorber has a circlip which is fixed axially on the piston rod. In this case, the support ring is supported on the piston rod in the pressing direction via the retaining ring. In particular, the retaining ring is a groove ring, in particular a snap ring. In this case, the retaining ring can be seated positively in a corresponding retaining ring groove on the piston rod. The support ring is preferably a solid part. Due to the form-fitting assembly of the support ring, tolerances can be compensated and the end run of the second end stop can also be improved.

In a further refinement it is provided that the support ring has a receiving section which is used and/or suitable for receiving the retaining ring in a form-fit connection. In particular, the receiving section is an annular groove complementary to the retaining ring, in which the retaining ring is accommodated in a form-fitting and/or precise-fitting manner at least axially and/or radially. The receiving section is particularly preferably formed by a cylindrical depression formed on the inner diameter. A support ring is therefore proposed which is characterized by a particularly stable seat.

In another refinement it is provided that the vibration absorber has an end stop damper which is arranged axially between the end stop ring and the piston rod guide. In particular, the end stop damper forms a mechanical end stop in the pulling direction of the piston rod. For this purpose, the end stop damper is preferably supported on the end stop ring in the extrusion direction. The end stop bumpers are preferably cylindrical or sleeve shaped. In particular, the end stop bumper is made of elastically deformable material, preferably rubber. The end stop damper thus prevents the end stop ring from directly abutting against the piston rod guide in the range of the limit stroke. The end stop ring preferably guides the stop force acting on the end stop damper directly into the piston rod. In other words, the force path extends from the end stop damper via 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.

Description of drawings

Further features, advantages and effects of the invention emerge from the following description of preferred embodiments of the invention. Shown here:

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

FIG. 2 shows a schematic sectional view of the hydraulic end stop according to FIG. 1 .

Detailed ways

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

The shock absorber 1 has a piston rod 4 , which is connected at the end to the piston rod 4 and is shown schematically, and a piston 5 which is guided movably along a longitudinal axis L in the damper tube 2 . To this end, the piston rod 4 is axially guided in the axial direction by the piston rod guide 6 , wherein the piston rod guide 6 simultaneously delimits the damping chamber 3 in the pulling direction Z. Furthermore, the piston 5 is axially guided 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 far away 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 shock absorber base (not shown). The two working chambers 7 , 8 are completely filled with a damping medium, such as oil.

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

The shock absorber 1 has a control sleeve 10 which is inserted into the damper tube 2 and delimits a control chamber 11 in the radial direction. The control chamber 11 is here 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 with respect to the longitudinal axis L on the piston rod 4 . The end stop ring 12 surrounds the piston rod 4 and is secured to the piston rod 4 in a non-positive manner, in particular axially fixed. 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 slidably supported in the axial direction on the piston rod 4 .

In the pulling phase, the hydraulic end stop 9 protrudes into the control sleeve 10 starting from a defined stroke position in the pulling direction Z, in particular in the end stroke region, and delimits the position formed on the piston. Control chamber 14 between rod guide 6 and control piston 13 . The volume of the control chamber 14 can vary depending on the axial position of the hydraulic end stop 9 in the control sleeve 10 . The end travel range here corresponds 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 the piston outer face 15 of the control piston 13 , via which the control piston 13 rests radially on the inner circumference of the control sleeve 10 when protruding into the control chamber 11 and is thus at least partially sealed. Control chamber 14.

Furthermore, the shock absorber 1 has an elastic end stop damper 16 which can alternatively be designed as a helical 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 has moved completely out of the damper tube 2 in the pulling direction Z, the end stop buffer acts as a mechanical end stop, wherein the stop force is transmitted to the piston via the end stop ring 12 Rod 4 in. In order to reduce the stop noise generated here, the end stop bumper 16 is usually made of elastic plastic or rubber.

The control piston 13 is movable in a limited manner along the piston rod 4 between a first end stop 17 and a second end stop 18 . In the illustrated embodiment, the first end stop 17 is delimited in the pulling direction Z by the end stop ring 12 and the second end stop 18 in the extrusion direction D by the support ring 22 limited. When the piston rod 4 performs a squeezing movement, the control piston 13 can be supported on the first end stop 17 in the pulling direction Z, and when the piston rod 4 is doing a pulling movement, the control piston 13 can be squeezed The direction D is supported on the second end stop 18 .

The control piston 13 is produced in one piece from a material section 19 . For example, the control piston 13 is produced from a casting, for example 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 around the longitudinal axis, which is formed by an annular shoulder formed on the end stop ring 12 . Conversely, the support ring 22 delimits the second end stop 18 in the pressing direction D with the second stop surface 21 . 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 opposing surfaces aligned parallel to one another.

The support ring 22 is supported on the piston rod 4 in the extrusion direction D via a stop ring 23 . The retaining ring 23 is, for example, a snap ring which is positively seated in a retaining ring groove, in particular an annular groove, on the outer circumference of the piston rod. The support ring 22 is a solid part and has on its inner diameter a receiving section 24 which receives the retaining ring 23 . The receiving section 24 is formed, for example, by a cylindrical depression in which the retaining ring 23 is accommodated positively 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 the flow of the damping medium defined between the control chamber 14 and the rest of the control chamber 11 , especially during the pulling phase. . When the piston rod 4 moves in the normal travel range, there is a radial distance between the piston outer side 15 and the damping tube 2 , so that the damping medium flows on the outside past the hydraulic end stop 9 and the hydraulic end stop 9 The lower stop does not work. With a greater stroke movement of the piston rod 4 in the end stroke region, the control channel 25 acts, so that the damping medium can flow through the control channel 25 from the control chamber 14 into the rest of the control chamber 11 during the pulling movement and During the squeezing movement, the control chamber 11 flows into the control chamber 14 . 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 additional damping The force is added to the damping force of the piston 5. During the pressing movement, the control piston 13 lifts off the support ring 22 , wherein the volume flow of the damping medium is released, so that the hydraulic end stop 9 produces 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 side 15 into the control chamber 14 in an annular gap 26 formed radially between the control piston 13 and the control sleeve 10 . For example, when the end stop damper 16 is deformed, a volume flow of the damping medium is ensured by the annular gap 26 , as a result of which the operational reliability of the shock absorber 1 can be significantly improved.

FIG. 2 shows the hydraulic end stop 9 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 evenly spaced from one another in the peripheral direction along a free area 28 . The free area 28 is a window-shaped recess and at the same time delimits the openings of the flow channels 25 , via which openings these flow channels open into the annular gap 26 . The stack 27 extends here from a first axial end face 29 of the control piston 13 in the direction of the first stop face 20 . When the first end stop 15 is reached, the control piston 13 is thus end-supported in the pulling direction Z by the butt 27 on the first stop surface 20 .

The end stop ring 12 has a narrowed section 30 by means of which the end stop ring 12 is fixed to the piston rod 4 , in particular to the annular groove, in a form-fitting and/or force-fitting manner. The narrowing section 30 directly adjoins the first stop surface 20 in the extrusion direction. Viewed in section, the narrowing section 30 here has a converging or conical cross-sectional course in the extrusion direction D. As shown in FIG. A self-locking in the extrusion direction D can thus be achieved by means of the narrowing section 30 , so that a high mechanical stop force can be transmitted by the end stop ring 12 into the piston rod 4 .

The stacks 27 each have on their radially inner sides an inclined surface 31 which is aligned in the same direction as the outer circumference of the narrowing section 30 . The control piston 13 can slide in the axial direction on the narrowing section 30 via the ramp 31 . In this case, the inclined surface 31 serves to guide and/or center the control piston 13 during the axial movement in order to prevent wedging of the control piston 13 in the control sleeve 10 .

The control channel 25 is formed by a first channel section 32 , a second channel section 33 and a third channel 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 the inner surface 35 of the control piston 13 . To this end, the first channel section 32 is formed between the stacks 31 via the free area 28 . The first channel section 32 is thus delimited or delimited in the circumferential direction by the stack 27 and in the axial direction on the one hand by the end stop ring 12 , in particular by the first stop surface 20 and the constriction. The segment 30 is delimited or bounded and, on the other hand, by the first axial end face 29 .

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 rest of the control chamber 11 to the inner surface 35 of the control piston 13 . The second channel section 33 is a recess, in particular a throttle groove, which is inserted into the second axial end face 36 of the control piston 13 . In the second end stop 18 , the control piston 13 rests on the second stop surface 21 over the entire surface or planarly with the second axial end surface 36 , wherein when the control piston 13 lifts off the end stop When the retaining ring 12 is closed, the free opening cross-section of the flow channel 25 , in particular the second channel section 33 , is enlarged or the flow resistance is reduced.

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 here formed by a gap formed between the piston rod 4 and the inner surface 31 , which is delimited in the pulling direction Z by the end stop ring 12 and in the pressing direction D by the support ring 22 limited. The channel section 34 can, for example, be delimited in its radial extension by a spacer element (not shown here) extending radially between the piston rod 4 and the inner surface 35 of the control piston 13 , for example a web , cam, etc. The spacer element simplifies the centering guidance of the control piston 13 on the piston rod 4 .

In order to facilitate insertion of the control piston 13 into the control sleeve 10 , the control piston 13 also has an entry surface 37 which can be formed by a surrounding radius or a surrounding chamfer. The entry surface 37 here connects the piston outer side 15 with the first axial end surface 29 , wherein the annular gap 26 is delimited by the entry surface 37 in the pressing direction, as described in FIG. 1 .

List of reference signs

1 shock absorber

2 damping tubes

3 damping chamber

4 piston rod

5 pistons

6 Piston rod guide

7 First studio

8 Second studio

9 Hydraulic end stops

10 Control sleeve

11 Control room

12 End stop ring

13 Control piston

14 Control chamber

15 Outer side of piston

16 End stop bumper

17 First end stop

18 Second end stop

19 Material section

20 First stop surface

21 Second stop surface

22 support ring

23 retaining ring

24 holding section

25 control channels

26 Annular gap

27 Stacks

28 vacant areas

29 First end face

30 narrowing section

31 sloped surface

32 First channel section

33 Second channel section

34 Third channel section

35 inner surface

36 Second end face

37 Entry face

D extrusion direction

L longitudinal axis

Z pull 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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