Damping valve device for a shock absorber of a motor vehicle

Abstract

The present invention relates to a vibration damper (10) of a motor vehicle, comprising an outer tube (12) and an inner tube (14) arranged coaxially thereto, and a working piston (18) arranged axially movable within the inner tube (14), which divides the interior of the inner tube (14) into a working chamber (22) on the piston rod side and a working chamber (24) remote from the piston rod, a damping valve device (54) arranged in the working piston (18), wherein the damping valve device (54) comprises: a coil (52), an axially movable armature (62) arranged at least partially within the coil (52), a main valve (68) with a main piston (76) which separates a pressure main control chamber (82a), a rebound main control chamber (82b) and a pilot control chamber (84) from one another, a pilot valve (70) which is designed such that it can be actuated in the rebound stage and in the compression stage by Hydraulic fluid can flow through,with a pilot working chamber (100) and a sliding tappet (102) arranged in the pilot working chamber (100), which is axially movable by means of the armature (62), and a connecting channel (98) arranged between the pilot control chamber (84) and the pilot working chamber (100) and fluidically connecting them, wherein the main piston (76) comprises a cylinder base region (76b) and a cylinder jacket region (76a) which forms the radially outer surface of the main piston (76).

Description

[0001] The invention relates to a damping valve device for a shock absorber for motor vehicles, wherein the damping valve device has a main valve and a pilot valve.

[0002] DE 10 2020 215 480 A1 discloses a vibration damper with a damping valve device. The damping valve device has a pilot valve adjustable via a solenoid coil. Particularly during dynamic operation of the vibration damper, unstable behavior of the damping valve can occur when the main valve opens and closes. In addition, acoustic problems arise during the switching process of the main valve. Furthermore, the damping valve devices are relatively large and therefore take up a lot of space.

[0003] The object of the present invention is therefore to provide a damping valve device for a vibration damper which is particularly space-saving and at the same time has a stable damping behavior in both the compression stage and the rebound stage and can be produced cost-effectively.

[0004] This object is achieved according to the invention by a vibration damper with a damping valve device having the features of independent device claim 1. Advantageous further developments emerge from the dependent claims.

[0005] According to a first aspect, a vibration damper of a motor vehicle comprises an outer tube and an inner tube arranged coaxially therewith, and a working piston arranged axially movable within the inner tube, which divides the interior of the inner tube into a working chamber on the piston rod side and a working chamber remote from the piston rod. The vibration damper also comprises a damping valve device arranged in the working piston, wherein the damping valve device has a coil and an axially movable armature arranged at least partially within the coil. The damping valve device also comprises a main valve with a main piston, which fluidically separates a pressure main control chamber, a tension main control chamber, and a pilot control chamber from one another.The damping valve device also has a pilot valve, which is designed and arranged such that hydraulic fluid can flow through it during the rebound and compression stages. It has a pilot working chamber and a sliding plunger arranged in the pilot working chamber, which is axially movable by means of the armature. Furthermore, the damping valve device has a connecting channel arranged between the pilot control chamber and the pilot working chamber, fluidically connecting them. The main piston comprises a cylinder base region and a cylinder jacket region, which forms the radially outer surface of the main piston.

[0006] The main piston is preferably hollow-cylindrical. The cylinder base region is preferably formed at the end region of the main piston pointing in the direction of the comfort valve. The cylinder jacket region preferably adjoins the cylinder base region directly in the direction of the drive region. The outer surface of the cylinder jacket region preferably forms the radially outermost surface of the main piston. The cylinder jacket region preferably has a constant cross-section. In particular, the cylinder jacket region has a constant outer diameter, so that a flat outer surface is preferably formed. The cylinder base region preferably has the main valve seat. The main piston preferably has a U-shaped or W-shaped longitudinal section. The cylinder jacket region is in particular tubular.Such a design of the main piston increases its stability when flowing through the damping valve device in the tension or compression direction. Tilting or canting of the main piston during axial movement is reliably minimized by this geometry.

[0007] The damping valve device is, for example, a pressure relief valve, which can preferably be pilot-operated. The main valve with the main piston is preferably designed to close and open the damping valve device, in particular the pressure relief valve. The main piston is preferably axially movable by means of the armature and / or the hydraulic pressure present in the pilot chamber.

[0008] A damping valve device designed as a pilot-operated pressure relief valve preferably comprises, in addition to the main valve, a pilot valve with a pilot working chamber and a sliding plunger arranged in the pilot working chamber, which is axially movable by means of the armature, and a connecting channel which is arranged between the pilot control chamber and the pilot working chamber and fluidically connects them to one another.

[0009] The damping valve device is arranged, for example, in a vibration damper for a motor vehicle. The vibration damper is, for example, a single-tube vibration damper or a multi-tube vibration damper, for example a twin-tube vibration damper. The vibration damper comprises, for example, an outer tube that forms an outer surface, in particular a housing, of the vibration damper. Arranged within the outer tube, coaxial with the outer tube, is an inner tube, also referred to as a damper tube. A compensation chamber is formed between the outer tube and the inner tube, which is preferably at least partially filled with a hydraulic fluid. For example, the compensation chamber is partially filled with a gas.

[0010] A working piston connected to a piston rod is preferably arranged within the inner tube in such a way that it is movable within the inner tube, wherein the inner tube is preferably designed as a guide for the working piston. A damping valve device, for example, is arranged on the working piston. The working piston divides the interior of the inner tube, in particular, into a first working chamber on the piston rod side and a second working chamber remote from the piston rod.

[0011] The vibration damper preferably has a sealing assembly that fluidically seals the interior of the outer tube on the piston rod side. Opposite the sealing assembly, at the end remote from the piston rod, the interior of the outer tube is preferably fluidically sealed by a base piece. In particular, a base valve is arranged on the base piece, which is attached to the end of the inner tube remote from the piston rod.

[0012] The damping valve device comprises a preferably cylindrical damping valve housing, which has a substantially tubular tube part and a housing upper part attached to the tube part or formed integrally therewith. The tube part has, for example, a connection area that has one or more connection contacts for an electrical power supply to the damping valve device. The connection contacts for an electrical power supply are preferably connected to a drive unit.

[0013] The damping valve device preferably has a drive designed as an electromagnet, in particular a coil with a plurality of windings made of a current-conducting wire. The coil is preferably arranged within a housing of the damping valve device and comprises, for example, a coil carrier onto which the windings of the coil are wound. The coil preferably at least partially or completely encloses an armature space that extends centrally in the axial direction. An armature is preferably mounted for axial movement within the armature space. The armature is preferably mounted within the armature space so as to be slidable in the axial direction and comprises, for example, a central armature rod, which is, for example, tubular in shape and extends centrally in the axial direction through the armature space.The armature space is preferably delimited by an at least partially hollow cylindrical pole tube, which preferably serves as a guide for the armature.

[0014] The damping valve device preferably comprises a main valve and a pilot valve. The pilot valve is preferably arranged downstream of the main valve in the flow direction in both the compression stage and the rebound stage of the vibration damper. In particular, hydraulic fluid can flow through the damping valve device in both directions. The damping valve device arranged in the working piston preferably has exactly one main valve and / or exactly one pilot valve. A seal, in particular a sealing ring, is attached to the working piston, for example, and seals the working piston in a fluid-tight manner to the damper tube. The working piston preferably comprises a first fluid passage to the working chamber on the piston rod side. The damping valve device is preferably fluidly connected to the working chamber on the piston rod side via the first fluid passage.The first fluid passage is designed, for example, as a fluid inlet for admitting hydraulic fluid into the damping valve device when the piston rod moves in the pulling direction, and as a fluid outlet for discharging hydraulic fluid from the damping valve device when the piston rod moves in the pushing direction. The working piston preferably has a second fluid passage to the working chamber remote from the piston rod, via which the damping valve device is preferably fluidically connected to the second working chamber remote from the piston rod. The second fluid passage is preferably designed as a fluid inlet for admitting hydraulic fluid into an optional comfort valve and / or the main valve when the piston rod moves in the pushing direction, and as a fluid outlet for discharging hydraulic fluid from the optional comfort valve and / or the main valve when the piston rod moves in the pulling direction.

[0015] The main valve preferably comprises a main piston which is arranged to be axially movable within a main working chamber. The main valve optionally comprises a housing part which at least partially delimits the main working chamber and forms an axial guide for the main piston. The housing part is in particular formed integrally with the pole tube, so that the pole tube preferably extends to the main piston and is in particular designed as an axial guide for the main piston. The main piston is preferably arranged in such a way that it fluidically separates a pressure main control chamber, a tension main control chamber, and a pilot control chamber from one another. The main control chamber is understood to be the hydraulic chamber, which is preferably directly adjacent to the main piston and preferably applies a hydraulic force to it in the opening direction of the main valve.A main valve through which fluid can flow in the rebound and compression stages preferably has a pressure main control chamber designed and arranged such that it applies a hydraulic force in the opening direction to the main piston in the compression stage, and a rebound main control chamber designed and arranged such that it applies a hydraulic force in the opening direction to the main piston in the rebound stage. The main valve preferably has a main valve seat, wherein, in an open position of the main valve, a main flow channel is formed between the main piston and the main valve seat. The rebound main control chamber and the pressure main control chamber are preferably fluidly connected to one another via the main flow channel.The hydraulic pressure of the working chamber remote from the piston rod is preferably present in the pressure main control chamber, while the hydraulic pressure of the working chamber on the piston rod side is preferably present in the tension main control chamber.

[0016] The main valve seat is preferably formed on a guide element mounted in a fixed position within the damping device, wherein the main piston is movable relative to the guide element. In particular, a spring assembly is mounted on the main piston, which spring assembly rests against the main valve seat of the guide element when the main valve is in the closed position. The spring assembly preferably comprises a plurality of, in particular two, spring disks arranged coaxially to one another and preferably abutting one another. The spring disk of the spring assembly pointing toward the main pressure control chamber preferably rests against the main valve seat and, in particular, has a bypass opening.

[0017] The pilot control chamber is understood to be the hydraulic chamber, which preferably borders directly on the main piston and preferably applies a hydraulic force to it in the closing direction of the main valve. The pilot control chamber is preferably arranged on the main piston opposite the main tension control chamber and the main pressure control chamber. For example, the main piston is designed such that the end face of the main piston facing the main pressure control chamber or the main tension control chamber, which is subjected to the hydraulic pressure of the main pressure control chamber or the main tension control chamber, is larger than the end face of the main piston facing the pilot control chamber, which is subjected to the hydraulic pressure of the pilot control chamber.

[0018] During operation of the damping valve device and during a movement of the piston rod in the pressure direction, the hydraulic fluid preferably flows from the working chamber remote from the piston rod through the second fluid passage into the optional comfort valve, into the main pressure control chamber, wherein the main piston is subjected to an opening force by the pressure in the main pressure control chamber and is moved axially upwards.

[0019] The main piston lifts off the main valve seat, and the hydraulic fluid flows through the main flow channel to the main control chamber, in particular the first fluid passage, and then into the piston rod-side working chamber. At the same time, in particular hydraulically parallel thereto, a partial flow of the hydraulic fluid flows through the pressure flow passage in the main piston to the pilot control chamber and applies a closing force to the main piston in the direction of the main valve seat. The closing force determines the opening width of the main valve, in particular the cross-section of the main flow channel, which determines the damping force of the damping valve device. The pressure in the pilot control chamber is preferably adjusted by the pilot valve, with the hydraulic fluid flowing from the pilot control chamber through the connecting channel into the pilot work chamber, which is opened by the sliding tappet.The opening width, in particular the outflow cross-section, of the connecting channel is preferably dependent on the axial position of the sliding plunger, which is adjusted by means of the solenoid coil. In the closed position of the pilot valve, the sliding plunger preferably completely closes the connecting channel, so that the hydraulic pressure in the pilot chamber rises to a maximum value and the main valve is closed by pressing the main piston onto the main valve seat. In an open position of the pilot valve, the connecting channel is at least partially opened by the sliding plunger.

[0020] According to a first embodiment, the main piston has a double U-shaped longitudinal section. In particular, the main piston has a W-shaped longitudinal section. The main piston is, for example, formed as a single piece or in one piece. Preferably, the main piston is rotationally symmetrical and, in particular, formed as a two-piece assembly.

[0021] According to a further embodiment, the damping valve device comprises a damping valve housing, wherein the cylinder jacket region, with its outer surface, bears against the inner surface of the damping valve housing, preferably in a fluid-tight manner. The outer surface is understood to be the radially outward-facing surface, and the inner surface is understood to be the radially inward-facing surface. Preferably, the damping valve housing forms an axial guide for the main piston. In particular, the main piston bears against the inner surface of the tubular part of the damping valve housing. Preferably, the radial outer surface bears completely against the inner surface of the damping valve housing.The contact of the cylinder jacket area with the inner surface of the damping valve housing ensures high stability of the main piston during axial movement, as it is guided on the radially outer surface, thus ensuring uniform force introduction into the main piston and reliably preventing jamming.

[0022] According to a further embodiment, the main piston has a central shoulder extending from the cylinder base region toward the armature. The shoulder is preferably arranged coaxially with the cylinder jacket region and has a smaller diameter than the cylinder jacket region. Optionally, the shoulder is formed as a separate component from the cylinder jacket region and the cylinder base region and is preferably firmly connected to the cylinder base region. The shoulder enables central force introduction into the main piston and thus ensures particularly stable axial movement of the main piston.

[0023] For example, a support area is attached to the pole tube, which is designed as an axial guide for the central shoulder and is arranged coaxially thereto. The central shoulder is preferably axially movable relative to the support area. It is also conceivable for the main piston to encompass the support area and for this to be attached to the central shoulder and coaxially thereto. For example, the support area is designed as a separate component from the cylinder jacket area, the cylinder base area and the shoulder. The support area in particular has a U-shaped longitudinal section. Preferably, the support area is attached to the end of the shoulder pointing in the direction of the drive area. A spring element is preferably attached to the support area. The support area enables a spring element to be supported on the main piston and offers a particularly compact design for the main piston.

[0024] According to a further embodiment, the cylinder jacket region has an annular end face that borders the pilot working chamber and is arranged such that the hydraulic pressure present in the pilot working chamber applies an axial force to the end face of the main piston in the closing direction of the main valve. The end face preferably points in the direction of the drive region. The end face is preferably completely circular. The hydraulic pressure applied to the end face is, for example, the discharge pressure in the flow direction behind the sliding tappet. The force introduction at the annular end face ensures stable guidance of the main piston in the axial direction, with low friction occurring and reliably preventing canting of the main piston.

[0025] According to a further embodiment, a spring element is arranged on the end face of the cylinder jacket region in such a way that it applies a spring force to the main piston in the closing direction of the main valve. The spring element is, for example, a spiral spring, a disc spring, and / or a spring washer. Preferably, one end of the spring element rests against the end face of the cylinder jacket region and the other end rests against the pole tube and / or the damping valve housing. The spring element provides additional stability for the main piston.

[0026] According to a further embodiment, the central shoulder is formed as a separate component and fastened to the cylinder base region. Preferably, the cylinder base region and the cylinder jacket region are formed as a single component or in one piece. The central shoulder has, for example, a region pointing in the direction of the cylinder base region and having a U-shaped longitudinal section. Preferably, the central shoulder is firmly connected to the cylinder base region, for example by pressing. Between the U-shaped region of the shoulder and the cylinder base region, for example, a hydraulic chamber is formed which is fluidically connected to the pilot control chamber via the flow passage formed in the shoulder and to the main pressure control chamber via the flow throttle. A separate design of the shoulder enables simple and cost-effective manufacture and assembly of the main piston.

[0027] According to a further embodiment, the sliding plunger is attached to the armature, in particular the armature rod, and rests, in particular fluid-tight, against the end face of the central shoulder in the closed position of the pilot valve. The sliding plunger preferably rests against the main piston in the closed position of the pilot valve in such a way that it fluidically closes the connecting channel. The armature and the sliding plunger are thus directly connected to one another, so that the solenoid coil acts directly on the pilot stage and the main stage of the damping valve device, thus preferably implementing follow-up control. Furthermore, such an attachment results in reduced friction of the pilot valve, since the plunger is guided by the armature rod.

[0028] According to a further embodiment, a pilot spring is arranged on the support region and on the sliding tappet in such a way that it applies an axial force to the sliding tappet in the opening direction of the pilot valve. The pilot spring is preferably a disc spring, disk spring, or spiral spring. The pilot spring preferably bears against the end face of the support region facing the drive region. The pilot spring preferably enables a fail-safe mechanism in the event that the coil is inadvertently de-energized. The pilot spring preferably bears against the sliding tappet and the main piston. In particular, the pilot spring is in the form of a spiral spring within a hollow cylindrical region of the main piston. The pilot spring also preferably ensures reduced friction of the pilot valve, since the sliding tappet is guided by the pilot spring.

[0029] According to a further embodiment, the damping valve device has a first pilot outflow channel for fluidically connecting the pilot working chamber to the piston rod-side working chamber, and a second pilot outflow channel for fluidically connecting the pilot working chamber to the working chamber remote from the piston rod. This enables separate outflow of hydraulic fluid from the pilot working chamber during the rebound and compression stages.

[0030] The first pilot outflow channel is preferably formed in the damping valve housing of the vibration damper and preferably extends from the pilot working chamber directly into the piston rod-side working chamber. The first pilot outflow channel preferably has a flow restrictor and / or a check valve arranged in such a way that hydraulic flow from the pilot working chamber into the piston rod-side working chamber is permitted and prevented in the opposite direction. The first pilot outflow channel is formed, for example, within the damping valve housing, preferably as an axial channel.

[0031] The second pilot outflow channel is preferably designed for the fluidic connection of the pilot working chamber to the working chamber remote from the piston rod. The second pilot outflow channel is formed in particular in the damping valve housing and preferably extends axially therethrough. The second pilot outflow channel preferably extends from the pilot working chamber directly into the working chamber remote from the piston rod. The second pilot outflow channel preferably has a flow restrictor and / or a check valve arranged to permit hydraulic flow from the pilot working chamber into the working chamber remote from the piston rod and prevent flow in the opposite direction.

[0032] According to a further embodiment, the pilot outflow channels are designed as flow bypasses for at least partially bypassing the pilot valve and the main valve. Preferably, the check valves of the pilot outflow channels each have at least one bypass opening.

[0033] According to a further embodiment, the pressure main control chamber is fluidically connected to the pilot control chamber via a first flow passage, and the rebound main control chamber is fluidically connected to the pilot control chamber via a second flow passage. The provision of a first and a second flow passage for connecting the main control chambers to the pilot control chamber ensures that fluid can flow through the pilot valve during the compression and rebound stages of the vibration damper. The pressure main control chamber and the rebound main control chamber are each fluidically connected to the pilot control chamber.

[0034] A flow throttle is preferably arranged in each of the first flow passage and the second flow passage. The first flow passage preferably extends at least partially or completely through the main piston, in particular through the cylinder base region, and preferably fluidically connects the pressure main control chamber to the pilot control chamber. The second flow passage preferably also extends through the main piston, in particular through the cylinder base region, and fluidically connects the rebound main control chamber to the pilot control chamber. A flow throttle in each flow passage enables separate adjustment of the flow throttling in the rebound and compression stages.

[0035] A check valve is preferably arranged in each of the first flow passage and the second flow passage, so that hydraulic fluid can flow exclusively in one direction through the first and second flow passages. The first flow passage preferably has a check valve arranged such that hydraulic flow from the main tension control chamber into the pilot control chamber is permitted and prevented in the opposite direction. The second flow passage preferably has a check valve arranged such that hydraulic flow from the main pressure control chamber into the pilot control chamber is permitted and prevented in the opposite direction.A check valve in each of the flow passages allows the hydraulic flows in the rebound and compression stages to be directed into the pilot chamber, so that the same pilot chamber and the connected pilot valve can be used in both the rebound and compression stages.

[0036] The first flow passage and the second flow passage are preferably arranged separately from each other. This ensures separate tunability of the damping valve device in the rebound and compression stages. The spring assembly, in particular, has a bypass opening arranged in alignment with the first flow passage.

[0037] According to a further embodiment, the connecting channel for the fluidic connection of the pilot control chamber to the pilot working chamber is formed in the central shoulder of the main piston. Preferably, the connecting channel is formed exclusively in the shoulder and in particular not in the cylinder base region and / or the cylinder jacket region. The connecting channel extends in particular centrally and in the axial direction through the main piston from the pilot control chamber into the pilot working chamber. Preferably, the connecting channel forms the fluid inlet to the pilot valve. The pilot working chamber is preferably directly connected to the connecting channel in fluidic terms. Preferably, the connecting channel in the main piston ensures a simple, direct fluidic connection of the pilot control chamber to the pilot working chamber, wherein the hydraulic fluid flows axially through the pilot working chamber in the direction of the armature.

[0038] The sliding plunger preferably rests against the main piston in the closed position of the pilot valve, fluidically closing the connecting channel. The main piston preferably forms a pilot valve seat against which the sliding plunger rests when the pilot valve is closed. The contact of the sliding plunger with the main piston enables follow-up control, with the sliding plunger directly applying a closing force to the main piston, which is transferred to the sliding plunger via the armature rod. This ensures high operational reliability.

[0039] According to a further embodiment, the main piston has a pull opening area which is directly adjacent to the pull main control chamber and a pressure opening area which is directly adjacent to the pressure main control chamber and wherein the ratio between the pull opening area and the pressure opening area is 1:1 to 5:1, in particular 2:1 to 4:1, preferably 3:1.

[0040] According to a further embodiment, the damping valve device comprises a comfort valve through which hydraulic fluid can flow in the compression stage and the rebound stage. In particular, the comfort valve comprises at least one comfort spring washer package, which for example comprises at least one or a plurality of spring washers that rest on a comfort valve seat. The comfort valve preferably has two spring washer packages, one designed to dampen the hydraulic fluid during a movement of the piston rod in the retraction direction and the other spring washer package designed to dampen the hydraulic fluid during a movement of the piston rod in the compression direction. The comfort valve is preferably fluidically connected directly to the working chamber remote from the piston rod. The comfort valve preferably forms the end of the working piston pointing towards the base valve.

[0041] For example, the damping valve device comprises a spring element mounted on the main piston in such a way that it applies a spring force to the main piston in the opening direction of the main valve. The spring element is preferably mounted on the side of the main piston facing the comfort valve. In particular, the spring element is designed as a spiral spring that is supported on a valve body of the comfort valve.

[0042] In particular, the main piston has a closing surface which is adjacent to the pilot control chamber and is arranged such that the hydraulic pressure present in the pilot control chamber acts on the closing surface of the main piston with an axial force in the closing direction of the main valve and wherein the closing surface is designed as a circular ring surface.

[0043] For example, the damping valve device comprises a bypass channel arranged in such a way that it fluidically connects the main pressure control chamber and the main tension control chamber. The bypass channel is preferably designed hydraulically parallel to the main flow channel as a bypass of the main valve. The bypass channel extends in particular from the main pressure control chamber to the main tension control chamber and fluidically connects them.

[0044] In particular, the sliding tappet has an opening surface which, in the closed position of the pilot valve, at least partially rests against the main piston, and wherein the opening surface has a recess. The opening surface is preferably formed on the end face of the sliding tappet facing the connecting channel and is preferably arranged such that, in the closed position of the pilot valve, it completely closes the connecting channel. The opening surface preferably has a recess pointing in the axial direction, in particular a central one, which is, for example, conical. The recess is, for example, cylindrical, with a round, circular, or angular cross-section. The recess preferably serves to enlarge the opening area and thus to adjust the opening pressure of the pilot valve. Description of the drawings

[0045] The invention is explained in more detail below using several embodiments with reference to the accompanying figures. Fig. 1 shows a schematic representation of a vibration damper in a longitudinal sectional view according to an embodiment. Fig. 2 shows a schematic representation of a damping valve device of a vibration damper in the compression stage in a longitudinal sectional view according to an embodiment. Fig. 3 shows a schematic representation of a damping valve device of a vibration damper in the rebound stage in a longitudinal sectional view according to an embodiment. Fig. 4 a schematic representation of a section of a damping valve device according to a further embodiment. Fig. 5 a schematic representation of a hydraulic circuit diagram of a damping valve device according to an embodiment.

[0046] Fig. 1 shows a vibration damper 10, wherein the vibration damper 10 is a multi-tube vibration damper, for example 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. An inner tube 14, which can also be referred to as a damper tube, is arranged coaxially within the outer tube 12. A compensation chamber 16 is formed between the outer tube 12 and the inner tube 14, which is preferably at least partially filled with a hydraulic fluid. For example, the compensation chamber 16 is partially filled with a gas.

[0047] 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, wherein the inner tube 14 is preferably designed as a guide for the working piston 18. The working piston 18 has a damping valve device 54. The working piston 18 divides the interior of the inner tube 14 into a first working chamber 22, which is arranged on the piston rod side, and a second working chamber 24, which is arranged remote from the piston rod.

[0048] The interior of the outer tube 12 is fluidically sealed on the piston rod side by means of a closure assembly 34. Opposite the closure assembly 34, at the end remote from the piston rod, the interior of the outer tube 12 is fluidically sealed by means of a base piece 36. A base valve 38 is arranged on the base piece 36, for example, and is attached in particular to the end of the inner tube 14 remote from the piston rod. The base valve 38 is, for example, a check valve through which flow can occur in both or only one direction. The second working chamber 24 is preferably fluidically connected to the compensation chamber 16 via the base valve 38. The piston rod-side end of the inner tube 14 and the outer tube 12 is preferably attached to the closure assembly 34.

[0049] The piston rod 20 has, for example, an optional pull stop which is subjected to a spring force via a spring element 42 during a movement in the pulling direction Z.

[0050] Fig. 2 shows an exemplary damping valve device 54, which is preferably arranged in the working piston 18 of the vibration damper 10. The damping valve device 54 is designed, for example, as a pilot-operated pressure relief valve and comprises a preferably cylindrical damping valve housing, which, for example, has a substantially tubular tube part 45 and a housing upper part 44, which is formed, for example, integrally with the tube part 45. The piston rod 20 is preferably attached to the housing upper part 44. The housing upper part 44 has, for example, a connection area (not shown), which has one or more connection contacts for an electrical power supply to the damping valve device 54. The connection contacts for an electrical power supply are preferably connected to a drive unit.

[0051] The damping valve device 54 has, for example, a drive region 48 and a valve region 50. The drive region 48 is arranged, for example, in the upper region of the damping valve device 54 facing the piston rod 20 and preferably substantially above, in particular in the pulling direction Z, the valve region 50. The drive region 48 preferably comprises a drive designed as an electromagnet. The electromagnet comprises a coil 52 with a plurality of windings made of a current-conducting wire. The coil 52 is preferably arranged within the tubular part 45 and concentrically thereto. For example, the coil 52 bears against the inner wall of the tubular part 45. A cover section 56 is arranged, for example, axially between the coil 52 and the upper housing part 44. The coil 52 preferably bears against the cover section 56 and is in particular fastened thereto.The cover section 56 is made, for example, from a metal, in particular a magnetizable material, preferably a material with low magnetic resistance. The coil 52 comprises, for example, a coil carrier onto which the windings of the coil are wound. The coil 52 at least partially or completely encloses an armature chamber 60 that extends centrally in the axial direction. An armature 62 is mounted for axial movement within the armature chamber 60. The armature 62 is preferably cylindrical and has a diameter that is slightly smaller than the diameter of the armature chamber 60, such that the armature 62 is preferably mounted so as to be slidable in the axial direction. For example, the armature 62 comprises a central armature rod 65, which, for example, has a round cross-section and extends centrally in the axial direction through the armature chamber 60.The armature chamber 60 is preferably defined by an at least partially hollow-cylindrical pole tube 64. The pole tube 64 extends, for example, from the drive region 48 into the valve region 50. The pole tube 64 is preferably formed from a magnetizable or magnetic material and, for example, has a magnetic separation 58.

[0052] Coil 52 is preferably designed and arranged such that, when energized, it creates a magnetic field having magnetic field lines that preferably extend substantially in the axial direction. Armature 62 is preferably made of a magnetizable or magnetic material and is movable in the axial direction according to the magnetic field created by coil 52.

[0053] The pole tube 64 is, in particular, multi-part, single-piece, or one-piece. The pole tube 64 has an upper tubular region, in particular with a constant inner diameter, which is preferably designed as a hollow cylinder and extends, for example, from the cover section 56 in the axial direction beyond the armature 62. A lower region with an enlarged diameter adjoins the upper hollow-cylindrical region in the axial direction, wherein the outer surface of the pole tube 64 preferably extends as far as the tubular part 45 and at least partially rests against it and is sealed in a fluid-tight manner to the tubular part 45, for example by a sealing element. The tubular part 45 at least partially or completely encloses a valve region 50 in the axial and circumferential directions, which valve region 50 will be explained in more detail in one of the following sections.

[0054] The valve region 50 comprises, for example, a main valve 68 and a pilot valve 70. The damping valve device 54 arranged in the working piston 18 preferably has exactly one main valve 68 and / or exactly one pilot valve 70. Hydraulic fluid can preferably flow through the main valve 68 and / or the pilot valve 70 when the piston rod 20 moves in the pulling direction Z and in the pushing direction D. A seal 26, such as a sealing ring, is preferably attached to the working piston 18 and seals the working piston 18 in a fluid-tight manner to the damper tube 14. The seal 26 preferably bears fluid-tight against the outer surface of the working piston 18 and against the inner surface of the damper tube 14. The damping valve device 54 further optionally has a comfort valve 28. The comfort valve 28 is preferably designed so that hydraulic fluid can flow through it in both the pushing direction D and the pulling direction Z.In particular, the comfort valve 28 comprises at least one comfort spring washer package 30, which, for example, comprises at least one or a plurality of spring washers that rest on a comfort valve seat.

[0055] The comfort valve 28 preferably has two spring washer packs, one designed to dampen the hydraulic fluid during a movement of the piston rod 20 in the pulling direction Z and the other spring washer pack designed to dampen the hydraulic fluid during a movement of the piston rod 20 in the pushing direction D. The comfort valve 28 is preferably fluidically connected directly to the working chamber 24 remote from the piston rod. The comfort valve 28 is preferably arranged in the working chamber 24 remote from the piston rod and, in particular, forms the end of the working piston 18 pointing in the direction of the base valve 36. The comfort valve 28 comprises, for example, a comfort valve housing 32, which is preferably separate from the tubular part 45 and firmly connected thereto or formed integrally with the tubular part 45. The seal 26 is preferably attached to the comfort valve housing 42 and connected thereto in a fluid-tight manner.The comfort valve housing 32 preferably encloses the comfort spring washer packages 30 axially and circumferentially.

[0056] The working piston 18 comprises a first fluid passage 39 to the first working chamber 22, wherein the first fluid passage 39 is formed, for example, in the tubular part 45, for example as a circular opening. The damping valve device 54 is preferably fluidically connected to the first, piston rod-side, working chamber 22 via the first fluid passage 39. The first fluid passage 39 comprises, for example, a plurality of passage bores in the tubular part 45. The first fluid passage 39 is designed, for example, as a fluid inlet for admitting hydraulic fluid into the damping valve device 54 when the piston rod 20 moves in the pulling direction Z, and as a fluid outlet for discharging hydraulic fluid from the damping valve device 54 when the piston rod moves in the pushing direction D.

[0057] The working piston 18, in particular the comfort valve 28, preferably has a second fluid passage 40 to the second working chamber 24, via which the damping valve device 54 is preferably fluidically connected to the second working chamber 24 remote from the piston rod. The second fluid passage 40 is designed, for example, as a fluid inlet for admitting hydraulic fluid into the comfort valve 28 and the main valve 68 when the piston rod 20 moves in the compression direction D, and as a fluid outlet for discharging hydraulic fluid from the comfort valve 28 and the main valve 68 when the piston rod moves in the tension direction Z.

[0058] During operation of the damping valve device 54, upon piston rod movement in the pulling direction Z, the hydraulic fluid flows, preferably from the first fluid passage 39 into the main valve 68, and into the pilot valve 70 and subsequently optionally through the comfort valve 28 and to the second fluid passage 40. The main valve 68 comprises a main piston 76, which is arranged to be axially movable within a main working chamber 78. The main valve 68 also comprises, for example, a housing part 80, which at least partially delimits the main working chamber 78 and forms an axial guide for the main piston 76. The housing part 80 is arranged, for example, coaxially to and within the tubular part 45. For example, the housing part 80 is formed integrally with the pole tube 64. A gap, in particular an annular space, is preferably formed between the housing part 80 and the tubular part 45.The main piston 76 is preferably arranged at least partially in the annular space between the housing part 80 and the tube part 45 and concentrically thereto.

[0059] The main piston 76 preferably divides the main working chamber 78 into a pressure main control chamber 82a, a tension main control chamber 82b, and a pilot control chamber 84. The main piston 76 has, in particular, a first flow passage 86a, which extends through the main piston 76 and forms a fluidic connection between the pressure main control chamber 82a and the pilot control chamber 84. For example, the first flow passage 86a extends in the axial direction through the main piston 76. The main piston 76 has, for example, a second flow passage 86b, which forms a fluidic connection between the tension main control chamber 82b and the pilot control chamber 84. The second flow passage 86b is, for example, arranged at the same height as the first fluid passage 39. The first and second flow passages 86a,b preferably each have a respective flow throttle 96a,b, in particular a cross-sectional constriction, and / or a check valve.The check valve in the first flow passage 86a is preferably arranged to allow flow from the pressure main control chamber 82a into the pilot control chamber 84. The check valve in the second flow passage 86b is preferably arranged to allow flow from the tension main control chamber 82b into the pilot control chamber 84.

[0060] The pressure main control chamber 82a is formed, for example, between the comfort valve 28 and the main piston 76. The tension main control chamber 82b is preferably formed, in particular, as an annular chamber at the fluid passage 39 to the first working chamber 22 and between the tubular part 45 and the main piston 76. The hydraulic pressure of the second working chamber 24, remote from the piston rod, is preferably present in the pressure main control chamber 82a, while the pressure of the first working chamber 22, on the piston rod side, is preferably present in the tension main control chamber 82b.

[0061] A guide element 72 is arranged, preferably in a fixed position, in the damping valve device 54 between the main valve 68 and the comfort valve 28. The guide element 72 is, for example, tubular and serves to conduct hydraulic fluid from the comfort valve 28 to the main valve 68. For example, the guide element 72 at least partially forms the main pressure control chamber 82a. The guide element 72 is optionally formed integrally with the valve body of the comfort valve 28 and arranged in a fixed position. A main valve seat 90 is preferably formed on the guide element 72. For example, a spring assembly 77 is attached to the main piston 76, which spring assembly rests against the main valve seat 90 of the guide element 72 when the main valve 68 is in the closed position. The spring assembly 77 preferably comprises a plurality of, in particular two, spring washers that are arranged coaxially to one another and preferably rest against one another.The spring disk of the spring assembly 77, which points toward the main pressure control chamber 82a, preferably rests against the main valve seat 90 and, in particular, has a bypass opening 74. The bypass opening 74 in the spring assembly 77 is preferably arranged in alignment with the first flow passage 86a.

[0062] In the open position of the main valve 68, in which the main piston 76 is moved axially away from the main valve seat 90, the main piston 76 and the spring assembly 77 are lifted from the main valve seat 90, so that a main flow channel 92 is formed between the main piston 76 and the main valve seat 90. The main flow channel 92 forms a fluid connection between the first and second working chambers 22, 24. In particular, the main flow channel 92 forms a fluid connection between the pressure main control chamber 82a and the tension main control chamber 82b. Optionally, the damping valve device 54 has a bypass channel, which is preferably hydraulically designed parallel to the main flow channel 92 as a bypass of the main valve 68.

[0063] The main piston 76 is preferably hollow-cylindrical. For example, the main piston 76 has a cylinder base region 76b, which points in the direction of the comfort valve 28, and an adjoining cylinder jacket region 76a, which points in the direction of the drive region 48. The cylinder jacket region 76a, for example, bears with its outer surface, in particular in a fluid-tight manner, against the tube part 45. With its inner surface, the cylinder jacket region 76a bears, in particular, in a fluid-tight manner, against the housing part 80 of the pole tube 64. The cylinder base region 76b preferably has the main valve seat 90 and the flow passages 86a,b. For example, the main piston 76 has a U-shaped or W-shaped longitudinal section. The main piston 76 preferably has a central shoulder 76c, which extends from the cylinder base region 76b in the direction of the armature rod 65 and is preferably arranged in alignment, in particular coaxially, with the latter.The central shoulder 76c is preferably arranged coaxially with the cylinder jacket region 76a and, in particular, has a round, preferably circular cross-section. For example, the shoulder 76c has the connecting channel 98 formed as a central axial bore.

[0064] A support region 76d is attached to the central shoulder 76c and coaxial therewith. The support region 76d preferably has a U-shaped longitudinal section with a central bore through which the central shoulder 76c extends. The support region 76d is preferably fastened to the outer surface of the central shoulder, for example, pressed or screwed. With its outer surface, the support region preferably bears fluid-tight against the pole tube 64, in particular the housing part 80. It is also conceivable for the support region 76d to be fastened to the housing part 80 and preferably to form an axial guide for the central shoulder 76c, wherein the central shoulder 76c preferably bears fluid-tight against the support region 76d.

[0065] The cylinder jacket area 76a of the main piston 76 preferably forms an annular end face A SP which points in the direction of the drive area 48. The front face A SPserves as the closing surface of the main piston 76. The cylinder base region 76b of the main piston 76 preferably has an annular surface 46 pointing in the direction of the drive region 48, which also serves as the closing surface As of the main piston 76 and borders the pilot control chamber 84, so that the hydraulic pressure present in the pilot control chamber 84 acts on the main piston 76, in particular the closing surface 46 of the main piston 76, with an axial force in the closing direction of the main valve. The pilot control chamber 84 is preferably delimited by the main piston 76, in particular the closing surface 46, the support region 76d and the cylinder jacket region 76a, and by the housing part 80.

[0066] The frontal area A SP borders on the pilot working chamber 100, so that the hydraulic pressure present in the pilot working chamber 100, the main piston 76, in particular the closing surface A SPof the main piston 76, is subjected to an axial force in the closing direction of the main valve 68. At the end face A SP In particular, a spring element 94 is attached, which applies a spring force to the main piston 76 in the closing direction. The spring element 94 is preferably supported on a shoulder in the pole tube 64 and / or a shoulder in the tubular part 45.

[0067] On the side of the main piston 76 facing the comfort valve, a further spring element 88 is mounted, for example, which is arranged in such a way that it applies a spring force to the main piston 76 in the opening direction. The spring element 94 is, for example, a coil spring that bears against the valve body of the comfort valve 28 and the main piston 76.

[0068] A connecting channel 98 is preferably formed in the main piston 76, which extends, in particular, centrally and in the axial direction therethrough from the pilot control chamber 84 into a pilot working chamber 100. Preferably, the connecting channel 98 forms the fluid inlet into the pilot valve 70. The pilot working chamber 100 is preferably fluidically connected directly to the connecting channel 98.

[0069] The pilot valve 70 comprises, for example, a sliding plunger 102, which is arranged to be axially movable within the pilot working chamber 100. The sliding plunger 102 is preferably attached to the armature 62, in particular the armature rod 65, with its end facing away from the main valve 68, so that the sliding plunger 102 moves with the armature 62. In a closed position of the pilot valve 70, the sliding plunger 102 preferably bears against the main piston 76 such that the connecting channel 98 is completely closed by the sliding plunger 102. In an open position of the pilot valve 70, the sliding plunger 102 is lifted off the main piston 76, so that the connecting channel 98 is opened by the sliding plunger 102 and a fluid flow occurs between the pilot control chamber 84 of the main valve 68 and the pilot working chamber 100. The sliding plunger 102 is preferably mounted axially movable relative to the main piston 76.Preferably, the sliding plunger 102 rests against the end face of the central shoulder 76c.

[0070] The sliding plunger 102 has, for example, a T-shaped longitudinal section, wherein the sliding plunger 102 has a first region facing the connecting channel 98 with a cross section that is larger than the cross section of the connecting channel 98 and a second region facing the armature 62 which has a smaller cross section than the first region.

[0071] In the closed position, the sliding tappet 102 preferably rests against a first valve seat formed in the main piston 76. The pilot working chamber 100 is preferably fluidly connected to the first fluid passage 39 and the second fluid passage 40. The pilot valve 70 preferably has a pilot spring 108 arranged such that it applies an axial force to the sliding tappet 102 in the opening direction of the pilot valve 70. The pilot spring 108 preferably serves as a fail-safe device in the event that the coil 52 is de-energized and is designed such that the hydraulic fluid flows out via the pilot outflow channel 104a and, in particular, a fail-safe valve arranged therein. The pilot spring 108 preferably rests against the sliding tappet 102 and the support region 76d of the main piston 76 or the pole tube 80.The leg regions of the U-shaped profile of the support region 76d form a circular end face, against which a pilot spring 108 is preferably supported. The pilot spring 108 is designed, for example, as a disc spring.

[0072] The sliding tappet 102 preferably has an opening surface 110, which is formed on the first region of the sliding tappet facing the connecting channel 98 and is arranged such that it closes the connecting channel 98 in the closed position of the pilot valve 70. The opening surface 110 is also referred to, for example, as the pilot opening surface A Pand preferably has an axially directed, in particular central, recess, which is, for example, conical. The recess can, for example, be cylindrical, with a round, circular, or angular cross-section. The recess preferably serves to enlarge the opening area and thus to adjust the opening pressure of the pilot valve 70.

[0073] The pilot valve 70 preferably comprises a first pilot outflow channel 104a, which is designed and arranged for the fluidic connection of the pilot working chamber 100 to the piston rod-side working chamber 22. The first pilot outflow channel 104a is formed, for example, in the pipe part 45 and preferably extends from the pilot working chamber 100 directly into the piston rod-side working chamber 22. Preferably, the first pilot outflow channel 104a has a check valve arranged such that a hydraulic flow from the pilot working chamber 100 into the piston rod-side working chamber 22 is enabled and prevented in the opposite direction.

[0074] The pilot valve 70 preferably comprises a second pilot outflow channel 104b, which is designed and arranged for the fluidic connection of the pilot working chamber 100 to the working chamber 24 remote from the piston rod. The second pilot outflow channel 104b is formed, for example, in the tubular part 45 and preferably extends axially therethrough. The second pilot outflow channel 104b preferably extends from the pilot working chamber 100 directly into the working chamber 24 remote from the piston rod. The second pilot outflow channel 104b preferably has a check valve arranged such that a hydraulic flow from the pilot working chamber 100 into the working chamber 24 remote from the piston rod is enabled and prevented in the opposite direction.

[0075] During operation of the damping valve device 54, upon movement of the piston rod 20 in the pressure direction D, the hydraulic fluid flows through the second fluid passage 40 into the optional comfort valve 28, into the pressure main control chamber 82a. The pressure in the pressure main control chamber 82a applies an opening force to the main piston 76, causing it to move axially upward. The main piston 76 lifts off the main valve seat 90, and the hydraulic fluid flows through the main flow channel 92 to the rebound main control chamber 82b, in particular the second fluid passage 39. At the same time, a partial flow of the hydraulic fluid flows through the first flow passage 86a in the main piston 76 to the pilot control chamber 84, applying a closing force to the main piston 76 in the direction of the main valve seat 90.The closing force determines the opening width of the main valve 68, in particular the cross-section of the main flow channel 92, which determines the damping force of the damping valve device 54. The pressure in the pilot control chamber 84 is adjusted by the pilot valve 70, with the hydraulic fluid flowing from the pilot control chamber 84 through the connecting channel 98 into the pilot working chamber 100, which is opened by the sliding tappet 102. The opening width of the connecting channel 98 depends on the axial position of the sliding tappet 102, which is adjusted, in particular predetermined, by means of a solenoid coil 54.In the closed position of the pilot valve 70, the sliding tappet 102 preferably completely closes the connecting channel 98, so that the hydraulic pressure in the pilot control chamber 84 rises to a maximum value and the main valve 68 is closed and preferably subjected to a force in the closing direction by pressing the main piston 76 onto the main valve seat 90. In an open position of the pilot valve 70, the connecting channel 98 is at least partially released by the sliding tappet 102, so that a hydraulic flow flows via a first pilot outflow channel 104a to the piston rod-side working chamber 22. The fluid flow during a movement of the piston rod 20 in the pressure direction D is in . Fig. 2 is schematically represented by the arrows, where the solid line represents the main flow through the main valve 68 and the broken line represents the pilot flow through the pilot valve 70.

[0076] Fig. 3 shows the damping valve device 54 of the Fig. 2, wherein the fluid flow is shown during a movement of the piston rod in the pulling direction Z. The main piston 76 preferably has a pulling opening area A Z and a pressure opening area A D The pressure opening area A D is the area of ​​the main piston 76 directly adjacent to the pressure main control chamber 82a, whereby the pull opening area A Z the area of ​​the main piston 76 directly adjacent to the main control chamber 82b. The ratio (A Z / A D ) between the tension opening area A Z and the pressure opening area A D is for example 1:1 to 5:1, in particular 2:1 to 4:1, preferably 3:1.

[0077] Fig. 4 is a detailed view of the main piston 76, wherein the vibration damper is essentially the same as that shown with reference to the Fig. The vibration damper described in Figures 1-3 corresponds to the one described in Figures 1-3, with the difference that the central shoulder 76c is formed separately from the cylinder jacket region 76a and the cylinder base region 76b. The shoulder 76c has, for example, a region pointing in the direction of the cylinder base region 76b with a U-shaped longitudinal section. Preferably, the central shoulder 76c is firmly connected to the cylinder base region 76a, for example by pressing. Between the U-shaped region of the shoulder 76c and the cylinder base region 76a, for example, a hydraulic chamber is formed, which is fluidically connected to the pilot control chamber 84 via the flow passage 86a formed in the shoulder and to the main pressure control chamber 82a via the flow throttle 96a.

[0078] Fig. Figure 5 shows a hydraulic circuit diagram of a damping valve device 54, where the solid lines represent the main flow and the broken lines the pilot flow. The hydraulic circuit diagram is merely exemplary and serves to simplify the hydraulic relationships of the Fig. 1 to 3 for a better understanding. The working chambers 22, 24 of the vibration damper 54 are fluidically connected to one another via the main volume flow flowing through the main valve 68 of the damping valve device 54. The pilot valve 70 is preferably hydraulically connected in parallel to the main valve 68. In particular, the pilot valve 70 is designed such that it Sof the main piston 76, in particular depending on the position of the sliding plunger 102, in particular the force of the pilot valve 70 introduced by the sliding plunger. For example, the pilot outflow channels 104a,b each have a check valve and a throttle, which is designed, for example, as a bypass opening in the check valve. The pilot outflow channels 104a,b are thus optionally designed as flow bypasses for at least partially bypassing the pilot valve 70 and the main valve 68. For example, the check valves in the flow passages 86a,b each have a bypass opening.

[0079] The hydraulic circuit diagram of the Fig. 5 shows, by way of example, that the damping valve 54 optionally has a bypass channel 112, which is, for example, attached to the main valve seat 90 and forms a bypass of the main valve 68.

[0080] Furthermore, the hydraulic circuit diagram shows the hydraulic pressure P Z in the rebound stage Z, the hydraulic pressure P D in pressure stage D, the pilot control pressure P P and the discharge pressure P AL shown. List of reference symbols 10 vibration dampers 12 Outer tube 14 inner tube 16 Compensation room 18 working pistons 20 piston rod 22 first / piston rod side working chamber 24 second / piston rod remote working chamber 26 Seal 28 Comfort valve 30 comfort spring washer package 32 comfort valve housing 34 closure package 36 floor pieces 38 bottom valve 39 first fluid passage to the first working chamber 22 40 second fluid passage to the second working chamber 24 42 spring element 44 Upper case 45 Pipe part 46 Front face / closing face 48 drive range 50 valve range 52 coil 54 Damping valve device 56 lid section 58 magnetic separation 60 anchor room 62 anchors 64 Pole tube 65 anchor rod 68 Main valve 70 Pilot valve 72 Guide element 74 Bypass opening 76 main pistons 76a Cylinder jacket area 76b Cylinder base area 76c central paragraph 76d support area 77 spring package 78 Main workroom 80 Housing part 82a, b Main control room for tension / compression 84 Pre-control room 86a, b flow passage 88 spring element 90 Main valve seat 92 Main flow channel 94 spring element 96a,b Flow restrictor 98 connecting channel 100 pilot workspace 102 sliding tappets 104a first pilot outflow channel 104b second pilot outflow channel 106 Housing element 108 pilot spring 110 Opening area of ​​the sliding tappet 112 Bypass channel As first closing surface of the main piston 76 A D Pressure opening area of ​​the main piston 76 A Z Main piston opening area 76 A SP second closing surface of the main piston 76 A P Pilot opening area QUOTES CONTAINED IN THE DESCRIPTION

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

[0000] DE 10 2020 215 480 A1

[0002]

Claims

[1] Vibration damper (10) of a motor vehicle, an outer tube (12) and an inner tube (14) arranged coaxially thereto and a working piston (18) arranged axially movable within the inner tube (14), which divides the interior of the inner tube (14) into a working chamber (22) on the piston rod side and a working chamber (24) remote from the piston rod, a damping valve device (54) arranged in the working piston (18), the damping valve device (54) comprising: a coil (52), an axially movable armature (62) arranged at least partially within the coil (52), a main valve (68) with a main piston (76) which separates a pressure main control chamber (82a), a tension main control chamber (82b) and a pilot control chamber (84) from each other, a pilot valve (70) which is designed such that it can be flowed through by hydraulic fluid in the rebound stage and in the compression stage, with a pilot working chamber (100) and a sliding tappet (102) arranged in the pilot working chamber (100) which is axially movable by means of the armature (62), and a connecting channel (98) which is arranged between the pilot control chamber (84) and the pilot working chamber (100) and fluidically connects them, characterized by , that the main piston (76) comprises a cylinder bottom region (76b) and a cylinder jacket region (76a) which forms the radially outer surface of the main piston (76). [2] Vibration damper (10) according to claim 1, wherein the main piston (76) has a double U-shaped longitudinal section. [3] Vibration damper (10) according to one of the preceding claims, wherein the damping valve device (54) has a damping valve housing (45) and wherein the cylinder jacket region (76a) rests with its outer surface against the inner surface of the damping valve housing (45). [4] Vibration damper (10) according to one of the preceding claims, wherein the main piston (76) has a central shoulder (76c) extending from the cylinder bottom region (76b) towards the armature (62). [5] Vibration damper (10) according to one of the preceding claims, wherein the cylinder jacket region (76a) has an annular end face (A SP ) which adjoins the pilot working chamber (100) and is arranged such that the hydraulic pressure present in the pilot working chamber (100), the end face (A SP ) of the main piston (76) is subjected to an axial force in the closing direction of the main valve (68). [6] Vibration damper (10) according to claim 5, wherein on the end face (A SP ) of the cylinder jacket area (76a) a spring element (94) is arranged such that it acts on the main piston (76) with a spring force in the closing direction of the main valve (68). [7] Vibration damper (10) according to one of claims 4 to 6, wherein the central shoulder (76c) is formed as a separate component and is attached to the cylinder bottom region (76b). [8] Vibration damper (10) according to one of claims 4 to 7, wherein the sliding plunger (102) is attached to the armature (64) and bears against the end face of the central shoulder (76c) in the closed position of the pilot valve (70). [9] Vibration damper (10) according to one of claims 5 to 8, wherein a pilot spring (108) is arranged on a support region (76d) and on the sliding tappet (102) in such a way that it applies an axial force to the sliding tappet (102) in the opening direction of the pilot valve (70). [10] Vibration damper (10) according to one of the preceding claims, wherein the damping valve device (54) has a first pilot outflow channel (104a) for fluidically connecting the pilot working chamber (100) to the piston rod-side working chamber (22) and a second pilot outflow channel (104b) for fluidically connecting the pilot working chamber (100) to the piston rod-remote working chamber (24). [11] Vibration damper (10) according to claim 10, wherein the pilot outflow channels (104a,b) are designed as flow bypasses for at least partially bypassing the pilot valve (70) and the main valve (68). [12] Vibration damper (10) according to one of the preceding claims, wherein the pressure main control chamber (82a) is fluidically connected to the pilot control chamber (84) via a first flow passage (86a) and the tension main control chamber (82b) is fluidically connected to the pilot control chamber (84) via a second flow passage (86b). [13] Vibration damper (10) according to one of the preceding claims, wherein the connecting channel (98) for fluidically connecting the pilot control chamber (84) to the pilot working chamber (100) is formed in the central shoulder (76d) of the main piston (76). [14] Vibration damper (10) according to one of the preceding claims, wherein the main piston (76) has a tension opening area (A Z ), which is directly adjacent to the train main control room (82b) and has a pressure opening area (A D ) which is directly adjacent to the main pressure control chamber (82a) and wherein the ratio (A Z / A D ) between the pull opening area (A Z) and the pressure opening area (A D ) 1:1 to 5:1, in particular 2:1 to 4:1, preferably 3:

1. [15] Vibration damper (10) according to one of the preceding claims, wherein the damping valve device (54) comprises a comfort valve (28) through which hydraulic fluid can flow in the compression stage and in the rebound stage.

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