Shock absorber for a motor vehicle and method for positioning a pre-tensioning element of the shock absorber

Abstract

The invention relates to a shock absorber (10) for a motor vehicle, having an outer tube (12) and an inner tube (14) arranged coaxially to the outer tube, and a working piston (18) arranged axially movably in the inner tube, which divides the inner space of the inner tube into a first working chamber (22) near the piston rod and a second working chamber (24) away from the piston rod; the shock absorber has a damping valve device (54) having a coil (52), an armature (62) which is axially movable, and a main valve (68), the armature being arranged at least partially in the coil, the main valve having a main piston (76) which separates a compression main control chamber (82a) from a rebound main control chamber (82b) from one another; a preloading element (74) is provided, which bears against the main piston, such that the preloading element exerts a force on the main piston in the opening direction of the main valve (68). The invention also relates to a method for positioning a preloading element (74) of a shock absorber (10).

Description

Technical Field

[0001] The present invention relates to a damping valve device for a shock absorber of a motor vehicle, the damping valve device having a main valve and a pilot valve. Background Technology

[0002] A vibration damper with a damping valve device is known from DE102020215480A1. This damping valve device has a pilot valve that can be adjusted via a magnetic coil. Especially during the dynamic operation of the vibration damper, unstable characteristics of the damping valve occur when the main valve is opened and closed. In particular, the spring characteristics are often unstable when the main valve is opened, which may generate additional acoustic problems. Furthermore, the assembly of this damping valve device is complex and costly. Summary of the Invention

[0003] Therefore, the object of the present invention is to provide a damping valve device for a shock absorber, which has stable opening and closing characteristics in both the compression and rebound phases, saves space, and can be manufactured simply and at low cost.

[0004] This task is accomplished according to the invention by a vibration damper having the features described in independent claim 1 and incorporating a damping valve device. Advantageous further extensions are obtained from the dependent claims.

[0005] According to a first aspect, a shock absorber for a motor vehicle includes an outer cylinder and an inner cylinder arranged coaxially with the outer cylinder, and a working piston axially movable inside the inner cylinder, the working piston dividing the internal space of the inner cylinder into a working chamber near the piston rod and a working chamber away from the piston rod. The shock absorber also includes a damping valve device, for example, arranged in the working piston, wherein the damping valve device has a coil and an armature axially movable, the armature being at least partially arranged inside the coil. The damping valve device also includes a main valve having a main piston that fluidly separates a compression main control chamber, a rebound main control chamber, and optionally a pilot control chamber from each other. The damping valve device also includes a preload element abutting against the main piston such that the preload element applies a force to the main piston in the opening direction of the main valve. Preferably, the preload element abuts against a surface of the main piston pointing towards the working chamber away from the piston rod, particularly towards the comfort valve.

[0006] The preload of the main piston in the opening direction improves the spring characteristics of the damping valve device. In particular, in pilot-controlled or especially follow-up-regulated damping valve devices, in the main valve pre-opened by means of a preload element, until a certain volume flow rate is achieved, it is not necessary to further open the main valve by piston movement.

[0007] The damping valve device is, for example, a pressure relief valve, which is preferably pilot-controlled. A main valve, having a main piston, is preferably configured to close and open the damping valve device, particularly the pressure relief valve. The main piston can preferably move axially, either indirectly via a pilot control valve located between the armature and the main piston, or directly by means of the armature and / or hydraulic pressure present in the pilot control chamber.

[0008] The damping valve device, configured as a pilot-controlled pressure relief valve, is preferably additional to the main valve and also includes a pilot valve having a pilot working chamber and a sliding tap disposed in the pilot working chamber, the sliding tap being axially movable by means of an armature. The damping valve device includes a connecting channel disposed between a pilot control chamber and a pilot working chamber, fluidly communicating the two chambers. Optionally, the damping valve device has a pilot valve configured and arranged such that it is saturated with hydraulic fluid during the springback and compression phases. This pilot valve has a pilot working chamber and a sliding tap disposed within the pilot working chamber, the sliding tap being axially movable by means of an armature. Furthermore, the damping valve device optionally includes a connecting channel disposed between a pilot control chamber and a pilot working chamber, fluidly communicating the two chambers. The compression main control chamber is preferably in fluid communication with the pilot control chamber via a first flow through-hole, and the rebound main control chamber is in fluid communication with the pilot control chamber via a second flow through-hole. In particular, the preload element is arranged in a central groove in the main piston, wherein the central groove is arranged coaxially with the connecting channel and directly abuts against the connecting channel or at least partially constitutes the connecting channel.

[0009] Damping valve devices are, for example, arranged in shock absorbers used in motor vehicles. These shock absorbers are, for example, monotube or multitube shock absorbers, such as twin-tube shock absorbers. The shock absorber includes, for example, an outer cylinder constituting the outer surface of the shock absorber, particularly a housing. Inside the outer cylinder, an inner cylinder, also referred to as the damping cylinder, is arranged coaxially with the outer cylinder. A balancing chamber is constructed between the outer and inner cylinders, which is preferably at least partially filled with hydraulic fluid. For example, the balancing chamber is partially filled with gas.

[0010] A working piston, connected to a piston rod, is preferably arranged inside the inner cylinder so that it can move within the inner cylinder, wherein the inner cylinder is preferably configured as a guide for the working piston. A damping valve device is, for example, arranged on the working piston. The working piston divides the internal space of the inner cylinder, in particular, into a first working chamber near the piston rod and a second working chamber away from the piston rod.

[0011] The shock absorber preferably has a sealing assembly that fluidly seals the internal space of the outer cylinder on the side near the piston rod. Opposite to the sealing assembly, at the end away from the piston rod, the internal space of the outer cylinder is preferably fluidly sealed by means of a bottom component. A bottom valve is particularly arranged on the bottom component, which is mounted on the end of the inner cylinder away from the piston rod.

[0012] The damping valve device includes a preferably cylindrical damping valve housing having a substantially tubular tubular portion and an upper housing portion mounted on or integrally constructed with the tubular portion. The tubular portion, for example, has a connection region with one or more connection contacts for supplying current to the damping valve device. Preferably, the connection contacts for supplying current are connected to a drive unit.

[0013] The damping valve device preferably has a drive portion configured as an electromagnet, particularly a coil having multiple turns of windings made of conductive metal wire. This coil is preferably arranged inside the housing of the damping valve device and includes, for example, a coil frame on which the coil windings are wound. Preferably, the coil at least partially or completely surrounds an armature space that extends centrally in the axial direction. Preferably, the armature is supported inside the armature space in a manner movable in the axial direction. The armature is preferably mounted inside the armature space in a manner slidable in the axial direction and includes, for example, a centrally located armature rod, which is exemplary configured as a tube and extends centrally through the armature space in the axial direction. The armature space is preferably defined by a pole shoe tube that is at least partially hollow and cylindrical, which preferably serves as a guide for the armature.

[0014] The damping valve assembly preferably includes a main valve and a pilot valve. The pilot valve is preferably located downstream of the main valve in both the compression and rebound phases of the damper, in the flow direction. In particular, the damping valve assembly is saturated with hydraulic fluid in both directions. Preferably, the damping valve assembly arranged in the working piston has exactly one main valve and / or exactly one pilot valve. A seal, particularly a sealing ring, is mounted on the working piston to fluidly seal it relative to the damper cylinder. The working piston preferably includes a first fluid passage to a working chamber near the piston rod. The damping valve assembly is preferably in fluid communication with the working chamber near the piston rod via the first fluid passage. The first fluid passage is configured, for example, as a fluid inlet for hydraulic fluid to flow into the damping valve assembly when the piston rod moves in the rebound direction, and as a fluid outlet for hydraulic fluid to flow out of the damping valve assembly when the piston rod moves in the compression direction. The working piston preferably has a second fluid passage to a working chamber remote from the piston rod, and the damping valve device preferably communicates with the second working chamber remote from the piston rod via the second fluid passage. The second fluid passage is preferably configured as a fluid inlet for allowing hydraulic fluid to flow into an optional comfort valve and / or main valve when the piston rod moves in the compression direction, and as a fluid outlet for allowing hydraulic fluid to flow out from the optional comfort valve and / or main valve when the piston rod moves in the rebound direction.

[0015] The main valve preferably includes a main piston arranged axially within a main working chamber. The main valve may optionally include a housing component that at least partially defines the main working chamber and forms an axial guide for the main piston. The main piston is preferably arranged such that it fluidly separates the compression main control chamber, the springback main control chamber, and the pilot control chamber from each other. The main control chamber can be understood as a hydraulic chamber preferably directly adjacent to the main piston and preferably applying hydraulic pressure to the main piston in the opening direction of the main valve. The main valve, capable of flow through in the springback and compression phases, preferably has a compression main control chamber and a springback main control chamber, the compression main control chamber being configured and arranged such that it applies hydraulic pressure to the main piston in the opening direction during the compression phase, and the springback main control chamber being configured and arranged such that it applies hydraulic pressure to the main piston in the opening direction during the springback phase. The main valve preferably has a main valve seat, wherein a main flow passage is formed between the main piston and the main valve seat in the open position of the main valve. The springback main control chamber and the compression main control chamber are preferably fluidly connected to each other via a main flow channel. The compression main control chamber preferably contains hydraulic pressure in a working chamber located away from the piston rod, while the springback main control chamber preferably contains hydraulic pressure in a working chamber located near the piston rod.

[0016] The main valve seat is preferably constructed on a guide element, which is fixedly mounted inside the damping device, wherein the main piston is movable relative to the guide element. The pilot control chamber can be understood as a hydraulic chamber preferably directly adjacent to the main piston and preferably applying hydraulic pressure to the main piston in the closing direction of the main valve. The pilot control chamber is preferably arranged on the main piston opposite to the springback main control chamber and the compression main control chamber. For example, the main piston is configured such that the end face of the main piston facing the compression main control chamber or the springback main control chamber (which is subjected to the hydraulic pressure of the compression main control chamber or the springback main control chamber) is greater 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).

[0017] During the operation of the damping valve device and as the piston rod moves in the compression direction, hydraulic fluid preferably flows from the working chamber away from the piston rod through the second fluid through-hole into an optional comfort valve and into the compression main control chamber. Here, the pressure in the compression main control chamber applies an opening force to the main piston, causing it to move axially upwards. The main piston then lifts from the main valve seat, and hydraulic fluid flows through the main flow channel to the rebound main control chamber, particularly to the second fluid through-hole, and subsequently into the working chamber near the piston rod. Simultaneously, particularly hydraulically in parallel with this flow, a portion of the hydraulic fluid flows through the compression flow through-hole in the main piston to the pilot control chamber and applies a closing force to the main piston towards the main valve seat. This closing force determines the opening width of the main valve, particularly 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 regulated by a pilot valve, where hydraulic fluid flows from the pilot control chamber through a connecting channel into the pilot working chamber, which is released by a sliding tappet. The opening width of the connecting channel, especially the outflow cross-section, preferably depends on the axial position of the sliding tappet, which is adjusted by means of a magnetic coil. In the closed position of the pilot valve, the sliding tappet preferably completely closes the connecting channel, causing the hydraulic pressure in the pilot control chamber to rise to its maximum value and close the main valve by pressing the main piston against the main valve seat. In the open position of the pilot valve, the connecting channel is at least partially released by the sliding tappet. The main piston, for example, has a first piston region on which a second piston region is axially connected, the diameter of which is smaller than that of the first piston region. The first flow through-pass preferably extends only through the first piston region of the main piston, especially centrally and axially through the first piston region into the pilot control chamber. Flow throttling in each flow through-pass allows for individual adjustment of flow throttling during the springback and compression phases.

[0018] According to the first embodiment, the preload element is mounted on the stationary element of the damping valve device by means of a fastening element. Specifically, the preload element is abutted against or fixedly mounted on the fastening element at one end. The other end of the preload element preferably abuts against the main piston. Preferably, the preload element is arranged in a central groove, particularly a bore, of the main piston. This central groove is preferably arranged coaxially with the connecting channel, preferably transitioning into or at least partially forming the connecting channel. The groove preferably extends centrally along the central axis of the damper.

[0019] According to another embodiment, the fastening element is force-locked and / or form-locked, especially press-fitted, to the stationary element. The stationary element is preferably statically mounted inside the working piston and, in particular, cannot move relative to the piston rod without damage. Specifically, the stationary element is fixedly connected to the tubular portion of the damping valve device. The fastening element is preferably cylindrically constructed, for example, as a pin or bolt. For example, the fastening element is press-fitted into a hole in the stationary element. The fastening element, in particular, has a centrally located shoulder for centering or securing the preload element on the fastening element.

[0020] According to another embodiment, the fastening element is connected to the stationary element so that it can move axially without damage. In particular, the fastening element is fastened to the stationary element in such a way that it can be positioned axially relative to the stationary element without damage, especially by applying an axial force to the fastening element. Preferably, the axial force for positioning the fastening element is applied to the fastening element by means of a tool that can be operated manually or automatically.

[0021] In another embodiment, the preload element is configured and abuts against the main piston such that the main valve is open in the operating state of the damper, in which the same pressure exists in each working chamber. The preload element preferably pre-opens the main valve, such that the main valve is at least slightly or fully open, especially in the de-energized state of the damping valve device and / or in the un-deflected state of the damper.

[0022] According to another embodiment, the damping valve device includes a comfort valve, wherein the stationary element is part of the comfort valve. The damping valve device preferably includes a comfort valve that is permeable to hydraulic fluid during the compression and rebound phases. In particular, the comfort valve includes at least one set of comfort spring washers, which, for example, includes at least one or more spring washers resting on a comfort valve seat. The comfort valve preferably has two sets of spring washers, one set configured to buffer the hydraulic fluid during piston rod movement in the rebound direction, and the other set configured to buffer the hydraulic fluid during piston rod movement in the compression direction. The comfort valve preferably includes a comfort valve body in which fluid passages are formed, which can be at least partially or completely fluidly closed by the comfort spring washer sets. Preferably, the stationary element includes the comfort valve body, wherein a hole for receiving a fastening element is specifically formed in the comfort valve body. The comfort valve preferably communicates directly with a working chamber remote from the piston rod. Preferably, the comfort valve forms the end of the working piston facing towards the bottom valve. The comfort valve is preferably hydraulically connected in series with a main valve. For example, a preload element is received in a screw or rivet of the comfort valve or main piston. The screw or rivet is preferably arranged such that it secures the valve gasket assembly to the main piston valve body.

[0023] In another embodiment, the preload element has a helical spring, a disc spring (Tellerfeder), and / or a spring washer (Federscheibe).

[0024] According to another embodiment, the preload element has a first spring element, a second spring element, and a guide element connected to each spring element. The spring elements are, for example, helical springs, disc springs, or spring washers. The preload element is particularly multi-piece constructed and includes, for example, a first spring element, a second spring element, and a guide element. The first spring element rests against the main piston, the second spring element rests against a fastening element, and the guide element is preferably directly connected to the first and second spring elements. The guide element is preferably cylindrical, particularly constructed as a pin or bolt, and is at least partially mounted in a hole in the stationary element. Preferably, the guide element is not fastened to the stationary element and is preferably slidably mounted relative to the stationary element. The guide element has a centrally located shoulder on its surface pointing towards the main piston for positioning the first spring element. Each spring element preferably rests against the guide element on its opposite side.

[0025] According to another embodiment, the fastening element is constructed as a solid cylindrical shape, a hollow cylindrical shape, a tubular shape, or an annular shape. The stationary element is, for example, a guide element in which the main valve seat is constructed. The annular fastening element is preferably pressed against the guide element, so that the fastening element can move, and in particular, be positioned, relative to the guide element in the axial direction without damage. The preload element is, in particular, constructed as a disc spring and rests against the annular fastening element and the main piston.

[0026] In another embodiment, the stationary element has a centrally located hole, into which a fastening element is mounted. The centrally located hole is preferably arranged coaxially with a preload element. In particular, the fastening element and the inner wall of the centrally located hole form an interference fit.

[0027] In another embodiment, the main piston separates the compression main control chamber, the rebound main control chamber, and the pilot control chamber from each other. The damping valve device has a pilot valve configured to be circulated by hydraulic fluid during the compression and rebound phases. The pilot valve has a pilot working chamber and a sliding tappet disposed in the pilot working chamber. The sliding tappet is axially movable by means of an armature. The damping valve device has a connecting channel disposed between the pilot control chamber and the pilot working chamber and fluidly communicating the pilot control chamber and the pilot working chamber with each other.

[0028] In particular, the main piston has a closing surface adjacent to the pilot control chamber and arranged such that the hydraulic pressure present in the pilot control chamber exerts an axial force on the closing surface of the main piston along the closing direction of the main valve, and the closing surface is configured as a shoulder in the main piston. The main piston is preferably constructed in a stepped manner, and in particular has a first piston region pointing toward the working chamber away from the piston rod, the first piston region preferably fluid-tightly abutting the housing component fixed in position to the damping valve device with its outer diameter. The first piston region is preferably constructed substantially cylindrical. A cylindrical second piston region is connected in particular to the first piston region, the second piston region being arranged coaxially with the first piston region and the diameter of the second piston region preferably being smaller than the diameter of the first piston region. An annular, preferably disk-shaped end face is preferably constructed on the first piston region, the end face pointing toward the drive region. The end face is preferably configured as the closing face of the main piston, especially the first closing face, and particularly adjacent to the pilot control chamber, such that the hydraulic pressure present in the pilot control chamber exerts an axial force on the main piston, especially the closing face of the main piston, along the closing direction of the main valve.

[0029] An annular end face is preferably constructed on the second piston region. This end face, pointing towards the drive region and particularly attached to the aforementioned closing surface, is configured as the second closing surface of the main piston. The second closing surface is adjacent to the pilot working chamber, such that the hydraulic pressure present in the pilot working chamber exerts an axial force on the second closing surface of the main piston along the closing direction of the main valve. The total closing surface of the main piston therefore preferably includes both the first and second closing surfaces. In particular, the size and / or position of the closing surfaces of the main piston are the same for the rebound load or compressive load of the damper. The sliding tappet is preferably arranged and configured such that the connecting channel can only be traversed by hydraulic fluid in one flow direction.

[0030] The present invention also includes a method for positioning the preload element of the above-mentioned shock absorber, wherein the method includes the following steps:

[0031] Place the preload element onto the main piston;

[0032] Pre-position the fastening element on the stationary element;

[0033] Apply hydraulic fluid flow to the damping valve device of the shock absorber;

[0034] The hydraulic pressure in the first working chamber and the second working chamber is continuously determined, and the pressure difference between the working chambers is continuously determined therefrom.

[0035] Compare the determined pressure difference with the target value;

[0036] When the determined differential pressure value deviates from the target value, the fastening element is moved in the axial direction.

[0037] Preferably, the target value is set manually or automatically according to the desired damping parameter. The pre-positioning of the fastening element within the stationary element preferably includes a crimp connection between the fastening element and the stationary element. Preferably, this crimp connection is configured such that it can be disengaged by a tool, allowing the fastening element to move axially, and in particular, to be positioned relative to the stationary element. Preferably, the fastening element moves axially only when the determined pressure difference deviates from the target value. When the target value is reached, especially when the determined pressure difference matches the target value, it is preferable to use a tool to prevent the fastening element from moving relative to the stationary element.

[0038] Preferably, when the pressure difference is greater than the target value, the fastening element is moved axially toward the main piston, and especially when the pressure difference is less than the target value, the fastening element is moved axially away from the main piston.

[0039] In another embodiment, the movement of the fastening element is achieved by means of a tool that can be operated manually or automatically. Attached Figure Description

[0040] The invention will now be described in detail with reference to the accompanying drawings and several embodiments.

[0041] Figure 1 A schematic diagram of a vibration damper according to one embodiment is shown in longitudinal sectional view.

[0042] Figure 2 A longitudinal sectional view shows a schematic diagram of a damper damping valve device according to an embodiment in the compression phase.

[0043] Figure 3 A longitudinal sectional view shows a schematic diagram of a damper damping valve device according to an embodiment in the rebound phase.

[0044] Figure 4 A schematic diagram of a damper damping valve device according to an embodiment is shown in longitudinal sectional view.

[0045] Figure 5 A schematic diagram of a damper damping valve device according to another embodiment is shown in longitudinal sectional view. Detailed Implementation

[0046] Figure 1 A vibration damper 10 is shown, which is a multi-tube vibration damper, such as a twin-tube vibration damper. The vibration damper 10 has an outer tube 12, which forms the outer surface of the vibration damper 10, particularly the housing. An inner tube 14, which can also be referred to as a damping tube, is arranged coaxially with the outer tube 12 inside the outer tube 12. A balancing chamber 16 is constructed between the outer tube 12 and the inner tube 14, which is preferably at least partially filled with hydraulic fluid. For example, the balancing chamber 16 is partially filled with gas.

[0047] A working piston 18, connected to a piston rod 20, is arranged inside the inner cylinder 14, allowing the working piston to move within the inner cylinder 14. The inner cylinder is preferably configured as a guide for the working piston 18. The working piston 18 has a damping valve device 54. The working piston 18 divides the internal space of the inner cylinder 14 into a first working chamber 22 located near the piston rod and a second working chamber 24 located away from the piston rod.

[0048] The internal space of the outer cylinder 12 is fluid-sealed on the side near the piston rod by means of a sealing assembly 34. Opposite to the sealing assembly 34, at the end away from the piston rod, the internal space of the outer cylinder 12 is fluid-sealed by means of a bottom member 36. A bottom valve 38 is arranged on the bottom member 36, for example, which is particularly mounted on the end of the inner cylinder 14 away from the piston rod. The bottom valve 38 is, for example, a check valve that can be circulated in two directions or only in one direction. The second working chamber 24 is preferably in fluid communication with the chamber balance chamber 16 via the bottom valve 38. The ends of the inner cylinder 14 and the outer cylinder 12 near the piston rod are preferably fastened to the sealing assembly 34.

[0049] The piston rod 20 may have, for example, an optional spring stop that is elastically applied via a spring element 42 when moving in the spring direction Z.

[0050] Figure 2 and Figure 3 Exemplary damping valve devices 54 are shown, which are preferably arranged in the working piston 18 of the damper 10. Figure 2 The arrows in the diagram illustrate the fluid flow during the compression phase, and... Figure 3 The flow of fluid during the rebound phase is indicated by arrows. The damping valve device 54 is configured, for example, as a pilot-controlled pressure-limiting valve and includes a preferably cylindrical damping valve housing, which has, for example, a substantially tubular tubular portion 45 and, for example, an upper housing portion 44 integrally constructed with the tubular portion 45. The piston rod 20 is preferably fixedly mounted on the upper housing portion 44. The upper housing portion 44 has, for example, a connection area (not shown) with one or more connection contacts for supplying current to the damping valve device 54. Preferably, the connection contacts for supplying current are connected to a drive unit.

[0051] The damping valve device 54, for example, has an actuation region 48 and a valve region 50. The actuation 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 the valve region 50, especially in the rebound direction Z. The actuation region 48 preferably includes an actuation portion configured as an electromagnet. The electromagnet includes a coil 52 having a multi-turn winding made of conductive metal wire. The coil 52 is preferably arranged concentrically with the tubular portion 45 inside the tubular portion. For example, the coil 52 rests against the inner wall of the tubular portion 45. A cover section 56 is arranged axially, for example, between the coil 52 and the upper housing portion 44. The coil 52 preferably rests against and is especially fastened to the cover section 56. The cover section 56 is made, for example, of metal, especially a magnetic material, preferably a material with low magnetic resistance. The coil 52 includes, for example, a coil frame on which the coil winding is wound. The coil 52 at least partially or completely surrounds an armature space 60 that extends centrally in the axial direction. The armature 62 is supported within the armature space 60 in a manner that allows axial movement. The armature 62 is preferably cylindrical and has a diameter slightly smaller than the diameter of the armature space 60, such that the armature 62 is preferably mounted in a manner that allows axial sliding. The armature 62 includes, for example, a centrally located armature rod 65, which has, for example, a circular cross-section and extends centrally through the armature space 60 in the axial direction. The armature space 60 is preferably defined by a pole shoe tube 64 that is at least partially hollow cylindrical. The pole shoe tube 64 is preferably constructed to be open at its bottom, particularly toward the valve region 50. The pole shoe tube 64 is preferably made of a magnetizable or magnetic material and has a magnetic isolation portion 58.

[0052] The coil 52 is preferably constructed and arranged such that it forms a magnetic field with magnetic lines of force when an electric current is applied, which preferably extend substantially axially in the armature space 60. The armature 62 is preferably made of a magnetizable or magnetic material and is movable axially according to the magnetic field formed by the coil 52.

[0053] An axially aligned and coaxially connected pole shoe tube element is attached to the hollow cylindrical region of the pole shoe tube 64, together forming the pole shoe tube 64, wherein the pole shoe tube 64 is constructed, particularly in a multi-piece, integral, or single-piece manner. The pole shoe tube 64 has an upper tubular region having a particularly constant inner diameter, which is preferably constructed as a hollow cylinder and extends axially, for example, from the cap section 56 beyond the armature 62. An axially connected lower region with an enlarged diameter is attached to the upper hollow cylindrical region, wherein the outer surface of the pole shoe tube 64 preferably extends to and at least partially abuts the tubular portion 45 and is fluidly sealed relative to the tubular portion 45, for example, via a sealing element. The tubular portion 45 at least partially or completely surrounds the valve region 50 in both the axial and circumferential directions, which is described in detail in one of the following paragraphs.

[0054] Valve region 50 includes, for example, a main valve 68 and a pilot valve 70. Preferably, the damping valve assembly 54 arranged in the working piston 18 has exactly one main valve 68 and / or exactly one pilot valve 70. Preferably, the main valve 68 and / or the pilot valve 70 are permeable to hydraulic fluid as the piston rod 20 moves in the rebound direction Z and the compression direction D. A seal, such as a sealing ring, is preferably mounted on the working piston 18 to fluidly seal the working piston 18 relative to the damper 14. The damping valve assembly 54 may also optionally have a comfort valve 28. The comfort valve 28 is preferably configured to be permeable to hydraulic fluid in both the compression direction D and the rebound direction Z. In particular, the comfort valve includes at least one comfort spring washer assembly, which includes, for example, at least one or more spring washers resting on the comfort valve seat. Preferably, the comfort valve 28 has two sets of spring washers, one set configured to buffer the pressure fluid when the piston rod 20 moves in the rebound direction Z, and the other set configured to buffer the pressure fluid when the piston rod 20 moves in the compression direction D. The comfort valve 28 preferably includes a comfort valve body 26 in which fluid passages are configured to be at least partially or completely fluidly closed by the comfort spring washers. The comfort valve 28 is preferably in direct fluid communication with the working chamber 24, which is located away from the piston rod. Preferably, the comfort valve 28 is arranged in the working chamber 24, away from the piston rod, and particularly at the end of the working piston 18 that faces towards the bottom valve 36.

[0055] The working piston 18 includes a first fluid passage 39 leading to a first working chamber 22. The first fluid passage 39 is constructed, for example, within a tubular portion 45, and is configured as a circular opening. The damping valve device 54 is preferably in fluid communication with the first working chamber 22 near the piston rod via the first fluid passage 39. The first fluid passage 39 is configured, for example, as a fluid inlet for allowing hydraulic fluid to flow into the damping valve device 54 when the piston rod 20 moves in the rebound direction Z, and as a fluid outlet for allowing hydraulic fluid to flow out of the damping valve device 54 when the piston rod moves in the compression direction D.

[0056] The working piston 18, and especially the comfort valve 28, preferably has a second fluid passage 40 to the second working chamber 24, and the damping valve device 54 is preferably in fluid communication with the second working chamber 24, which is located away from the piston rod, via the second fluid passage. The second fluid passage 40 is configured, for example, as a fluid inlet for allowing hydraulic fluid to flow 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 allowing hydraulic fluid to flow out of the comfort valve 28 and the main valve 68 when the piston rod moves in the rebound direction Z.

[0057] During operation of the damping valve device 54, as the piston rod moves in the rebound direction Z, hydraulic fluid preferably flows into the main valve 68 from the first fluid passage 39, and then into the pilot valve 70, and optionally through the comfort valve 28 and to the second fluid passage 40. The main valve 68 includes a main piston 76, which is axially movable within the main working chamber 78. The main valve 68 also includes, for example, a housing component 80, which at least partially defines the main working chamber 78 and forms an axial guide for the main piston 76. The housing component 80 is arranged, for example, coaxially with the tubular portion 45 within the tubular portion. A gap, particularly an annular space, is preferably formed between the housing component 80 and the tubular portion 45. The main piston 76 is preferably arranged concentrically with the housing component 80 within the housing component 80. The main piston 76 preferably divides the main working chamber 78 into a compression main control chamber 82a, a rebound main control chamber 82b, and a pilot control chamber 84. The main piston 76 has a first flow through-hole 86a that extends through the main piston 76 and forms fluid communication between the compression main control chamber 82a and the pilot control chamber 84. For example, the first flow through-hole 86a extends centrally along the axial direction through the main piston 76. The housing component 80 has, for example, a second flow through-hole 86b that forms fluid communication between the rebound main control chamber 82b and the pilot control chamber 84. The second flow through-hole 86b is, for example, arranged at the same height as the first flow through-hole 39. The first flow through-hole 86a and the second flow through-hole 86b preferably have corresponding flow throttling portions 96a and 96b, respectively, and in particular, cross-sectional contractions.

[0058] The compression main control chamber 82a is, for example, constructed between the comfort valve 28 and the main piston 76. The rebound main control chamber 82b is preferably constructed as the aforementioned gap, particularly an annular space, between the housing component 80 and the tubular portion 45. Hydraulic pressure is preferably present in the compression main control chamber 82a in a second working chamber 24, away from the piston rod, while pressure is preferably present in the rebound main control chamber 82b in a first working chamber 22, near the piston rod.

[0059] Between the main valve 68 and the comfort valve 28, a guide element 72 is preferably fixedly arranged in the damping valve assembly 54. The guide element 72 is, for example, tubularly constructed and serves to guide hydraulic fluid from the comfort valve 28 to the main valve 68. For example, the guide element 72 at least partially constitutes the compression main control chamber 82a. The guide element 72 is preferably directly or indirectly connected to the tubular portion 45 and is fixedly arranged relative to the tubular portion. A main valve seat 90 is preferably constructed on the guide element 72. A spring assembly (not shown) is mounted on the main piston 76, for example, abutting against the main valve seat 90 of the guide element 72 in the closed position of the main valve 68.

[0060] The main piston 76 is lifted from the main valve seat 90 in the open position of the main valve 68—in which the main piston 76 moves axially away from the main valve seat 90—thereby forming a main flow passage 92 between the main piston 76 and the main valve seat 90. The main flow passage 92 forms fluid communication between the first working chamber 22 and the second working chamber 24. In particular, the main flow passage 92 forms fluid communication between the compression main control chamber 82a and the rebound main control chamber 82b.

[0061] The main piston 76 is preferably constructed in a stepped manner and, for example, has a first piston region 113 pointing toward the working chamber 24 away from the piston rod, which fluid-tightly abuts the housing component 80 with its outer diameter. The first piston region 113 is constructed substantially cylindrically, for example. A cylindrical second piston region 114 is connected to the first piston region 113, which is arranged coaxially with the first piston region 113 and has a smaller diameter than the first piston region 113. An annular end face 46 pointing toward the drive region 48 is preferably constructed on the main piston 76, especially on the first piston region 113. The end face 46 serves as the closing surface A of the main piston 76. SFurthermore, it is adjacent to the pilot control chamber 84, such that the hydraulic pressure present in the pilot control chamber 84 exerts an axial force on the main piston 76, particularly the closing surface 46 of the main piston 76, along the closing direction of the main valve. The pilot control chamber 84 is preferably defined by the closing surface 46, the housing component 80, and the second region of the main piston 76, particularly the main piston 76. The first flow passage 86a for communicating with the compression main control chamber 82a preferably extends only through the first region of the main piston 76, particularly extending centrally along the axial direction through this first region into the pilot control chamber 84. The first flow passage 86a preferably has a check valve arranged to allow hydraulic flow from the compression main control chamber 82a to the pilot control chamber 84 and to prevent hydraulic flow in the opposite direction. The second flow passage 86b preferably also has a check valve arranged to allow hydraulic flow from the rebound main control chamber 82b to the pilot control chamber 84 and to prevent hydraulic flow in the opposite direction.

[0062] On the main piston 76, especially in the second piston region 114, an annular end face A pointing toward the drive region 48 is preferably constructed. SP End face A SP Attached to closed surface A S Another closing surface used as the main piston 76, especially the second closing surface A SP Furthermore, it is adjacent to the pilot working chamber 100, such that the hydraulic pressure present in the pilot working chamber 100 exerts pressure on the main piston 76, especially the closing surface A of the main piston 76, along the closing direction of the main valve 68. SP Apply axial force.

[0063] A spring element 94 is mounted on the side of the main piston 76 facing away from the main valve seat 90. This spring element is arranged such that it applies an elastic force to the main piston 76 toward the main valve seat 90. The spring element 94 is, for example, a helical spring, which rests against the inner surface of the hollow cylindrical region of the housing component 80 and is supported at one end on the closing surface 46, particularly the closing surface A, of the main piston 76 in the direction toward the drive region 48. S The spring element 94 is preferably supported at the other end on the housing component 80. The housing component has, for example, a groove in which the spring element 94 is arranged.

[0064] A connecting channel 98 is preferably constructed in the main piston 76, extending centrally and axially through the main piston from the pilot control chamber 84 into the pilot working chamber 100. Preferably, the connecting channel 98 forms a fluid inlet to the pilot valve 70. A region of the main piston 76 pointing toward the drive region 48 is constructed, for example, in a hollow cylindrical shape, wherein the interior of this hollow cylindrical region preferably at least partially constitutes the pilot working chamber 100. The pilot working chamber 100 is preferably directly fluidly connected to the connecting channel 98.

[0065] The pilot valve 70 includes, for example, a sliding pusher 102, which is axially movable within the pilot working chamber 100. The sliding pusher 102 preferably rests against the armature 62, particularly the armature rod 65, at its end opposite to the main valve 68, such that the movement of the armature 62 and the sliding pusher 102 is coupled at least when the armature 62 moves toward the sliding pusher 102. The sliding pusher 102 is preferably resting against the main piston 76 in the closed position of the pilot valve 70, such that the connection passage 98 is completely closed by the sliding pusher 102. In the open position of the pilot valve 70, the sliding pusher 102 is lifted from the main piston 76, such that the connection passage 98 is released by the sliding pusher 102, allowing fluid flow between the pilot control chamber 84 of the main valve 68 and the pilot working chamber 100. The sliding pusher 102 is preferably mounted in a manner that allows axial movement relative to the main piston 76. In particular, the sliding tappet 102 is axially guided by the main piston 76 and preferably, especially fluid-tightly, abuts against the inner wall of the hollow cylindrical region of the main piston 76.

[0066] The sliding push rod 102 has, for example, a T-shaped longitudinal section, wherein the sliding push rod 102 has a first region facing the connecting channel 98 and a second region facing the armature 62, the cross-section of the first region being larger than the cross-section of the connecting channel 98, and the second region having a larger cross-section than the first region. The second region preferably extends over the entire cross-section of the pilot working chamber 100.

[0067] Preferably, the sliding push rod 102 rests against a first valve seat in the closed position, the first valve seat being constructed in the main piston 76.

[0068] The sliding push rod 102 preferably has an opening surface 110, which is constructed on a first region of the sliding push rod facing the connecting channel 98 and 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 pilot opening surface A. P It is also preferable to have a groove pointing in the axial direction, particularly centered, which is, for example, conical in shape. This groove can be cylindrical, for example, with a circular, annular, or polygonal cross-section. This groove is preferably used to increase the opening surface and therefore to regulate the opening pressure of the pilot valve 70.

[0069] The pilot valve 70 preferably includes a first pilot outflow passage 104a, which is configured and arranged to fluidly communicate the pilot working chamber 100 with the first fluid passage 39, preferably the working chamber 22 adjacent to the piston rod. The first pilot outflow passage 104a is constructed, for example, in the housing component 80, particularly in a housing element fixedly connected to the housing component, and preferably extends from the pilot working chamber 100 into the springback main control chamber 82b. The first pilot outflow passage 104a preferably has a check valve arranged to allow hydraulic flow from the pilot working chamber 100 to the first fluid passage 39 and to prevent hydraulic flow in the opposite direction.

[0070] The pilot valve 70 preferably includes a second pilot outlet passage 104b, which is configured and arranged to fluidly communicate the pilot working chamber 100 with the second fluid passage 40, preferably the working chamber 24 remote from the piston rod. The second pilot outlet passage 104b is, for example, constructed in the main piston 76 and preferably extends axially through the main piston, particularly through the first and second piston regions. The second pilot outlet passage 104b preferably extends from the pilot working chamber 100 into the compression main control chamber 82a. The second pilot outlet passage 104b preferably has a check valve arranged to allow hydraulic flow from the pilot working chamber 100 to the second fluid passage 40 and to prevent hydraulic flow in the opposite direction.

[0071] During the operation of the damping valve device 54, as the piston rod 20 moves along the compression direction D, hydraulic fluid flows into the comfort valve 28 through the second fluid passage 40 and enters the compression main control chamber 82a. The pressure in the compression main control chamber 82a applies an opening force to the main piston 76, causing it to move axially upwards. Here, the main piston 76 is lifted from the main valve seat 90, and hydraulic fluid flows through the main flow passage 92 to the rebound main control chamber 82b, particularly to the second fluid passage 39. Simultaneously, a portion of the hydraulic fluid flows through the first flow passage 86a in the main piston 76 to the pilot control chamber 84 and applies a closing force to the main piston 76 towards the main valve seat 90. This closing force determines the opening width of the main valve 68, particularly the cross-section of the main flow passage 92, which in turn determines the damping force of the damping valve device 54. The pressure in the pilot control chamber 84 is regulated by the pilot valve 70, through which hydraulic fluid flows from the pilot control chamber 84 into the pilot working chamber 100 via a connecting passage 98, which is released by the sliding pusher 102. The opening width of the connecting passage 98 depends on the axial position of the sliding pusher 102, which is adjusted by means of the magnetic coil 54 and is, in particular, predetermined. In the closed position of the pilot valve 70, the sliding pusher 102 preferably completely closes the connecting passage 98, causing the hydraulic pressure in the pilot control chamber 84 to rise to its maximum value and close the main valve 68, preferably applying force in the closing direction by pressing the main piston 76 against the main valve seat 90. In the open position of the pilot valve 70, the connecting passage 98 is at least partially released by the sliding pusher 102, allowing hydraulic flow to flow into the pilot working chamber 100 and through the first pilot outflow passage 104a to the springback main control chamber 82b, and in particular to the second fluid passage 39. The fluid flow during the movement of piston rod 20 along the compression direction D Figure 2 The arrows are used to illustrate the flow, with solid lines indicating the main flow through main valve 68 and dashed lines indicating the pilot flow through pilot valve 70.

[0072] Figure 3 Show Figure 2 The damping valve device 54 illustrates fluid flow during piston rod movement in the rebound direction. The main piston 76 preferably has a rebound opening surface A. Z and compression opening surface A D Compress and open surface A D The surface of the main piston 76 directly adjacent to the compression main control chamber 82a, wherein the springback opening surface A Z It is the surface of the main piston 76 that is directly adjacent to the springback main control chamber 82b.

[0073] A preload element 74 is abutted against the main piston 76, for example, such that the preload element applies a preload force to the main piston 76 in the opening direction of the main valve 68. The preload element 74 is preferably a coil spring, a disc spring, or a spring washer. The preload element 74 is abutted against, for example, the surface of the main piston 76 pointing toward the second working chamber 24, and especially toward the comfort valve 28. Preferably, the preload element 74 is arranged in a centrally located groove 77, or in particular a bore, in the main piston 76. This centrally located groove 77 is preferably arranged coaxially with the connecting channel 98, preferably transitioning into or at least partially constituting the connecting channel 98. The groove 77 preferably extends centrally along the central axis of the damper 10.

[0074] The main valve 68 is preferably in the open position when the damper 10 is in the following operating state, in which the same pressure exists in the two working chambers 22, 24.

[0075] The preload element 74 is preferably mounted at one end on the main piston 76 and at the other end on the stationary element of the damper 10, particularly the damping valve assembly 54. Preferably, the preload element 74 is fastened to the stationary element by means of a fastening element 32. This stationary element is preferably stationary inside the working piston 18 and, in particular, cannot move relative to the piston rod 20 without damage. Specifically, this stationary element is fixedly connected to the tubular portion 45 of the damping valve assembly 54. This stationary element is preferably part of the comfort valve 28, particularly the comfort valve body 26. The comfort valve body 26, for example, has a centrally located bore 66 that extends axially through the valve body.

[0076] The fastening element 32 is, for example, a cylindrical pin or bolt. Preferably, the fastening element 32 is form-locked and / or force-locked connected to the stationary element. For example, the fastening element 32 is press-fitted to the stationary element, particularly into a hole 66 in the stationary element. The fastening element 32 particularly has a centrally located shoulder for centering and / or securing the preload element 74 to the fastening element 32. Preferably, the fastening element 32 is fastened inside the stationary element in such a way that the fastening element can move axially without damage.

[0077] stationary elements in Figure 2 and 3 In some embodiments, the example is the comfort valve body 26.

[0078] Figure 4 Another embodiment of the damping valve device 54 is shown, which largely corresponds to Figure 2 and 3 The damping valve device. With Figure 2 and 3 The difference in damping valve device 54 is: Figure 4The damping valve device 54 has a multi-piece preload element 74. The preload element 74 includes, for example, a first spring element 74a abutting against the main piston 76, a second spring element 74c abutting against the fastening element 32, and a guide element 74b directly adjacent to the first spring element 74a and the second spring element 74c. The guide element 74b is preferably cylindrical, particularly constructed as a pin or bolt, and is at least partially mounted in a hole 66 in the stationary element. Preferably, the guide element 74b is not fastened to the stationary element and is preferably mounted in a manner that allows it to slide relative to the stationary element. The guide element 74b has a centrally located shoulder on its surface pointing toward the main piston 76 for positioning the first spring element 74a. The spring elements 74a and 74c preferably abut against the guide element on opposite sides of the guide element 74b. The preload element 74 preferably resists the spring element 94, wherein the spring element 94 and the preload element 74 are preferably balanced in a defined pre-opening of the piston.

[0079] Figure 5 Another embodiment of the damping valve device 54 is shown, which largely corresponds to Figure 2 , 3 And 4's damping valve device. With Figure 2 , 3 The difference between the damping valve device 54 and 4 is that... Figure 5 The damping valve assembly 54 has an annular fastening element 32. The stationary element is a guide element 72, in which the main valve seat 90 is constructed. The annular fastening element 32 is preferably pressed against the guide element 72, allowing the fastening element 32 to move, and especially position, relative to the guide element 72 in the axial direction without damage. The preload element 74... Figure 5 In some embodiments, it is configured as a disc spring and rests against the annular fastening element 32 and the main piston 76.

[0080] The positioning of the preload element 74 in the damper 10, particularly the damping valve device 54, preferably includes the following steps:

[0081] Place the preload element 74 onto the main piston;

[0082] The fastening element 32 is pre-positioned on the stationary element;

[0083] A hydraulic fluid flow is applied to the damping valve device 54 of the shock absorber 10;

[0084] The hydraulic pressure in the first working chamber 22 and the second working chamber 24 is continuously determined, and the pressure difference between each working chamber 22 and 24 is determined therefrom;

[0085] Set a target value for the differential pressure and compare the determined differential pressure with the target value;

[0086] When the determined differential pressure value deviates from the target value, the fastening element 32 is moved in the axial direction, especially by means of a tool that can be operated manually or automatically.

[0087] The pre-positioning of the fastening element within the stationary element preferably includes forming a crimp connection between the fastening element and the stationary element. Preferably, this crimp connection is configured such that it can be disengaged by means of a tool, thereby allowing the fastening element to move in the axial direction, and in particular, to be positioned relative to the stationary element. Preferably, the fastening element moves in the axial direction only when the determined pressure difference deviates from a target value. When the target value is reached, especially when the determined pressure difference matches the target value, it is preferable to use a tool to prevent the fastening element from moving relative to the stationary element.

[0088] List of reference numerals

[0089] 10 shock absorbers

[0090] 12 outer cylinder

[0091] 14 Inner cylinder

[0092] 16 Balance Chambers

[0093] 18 Working piston

[0094] 20 Piston Rod

[0095] 22 First working chamber / Working chamber near the piston rod

[0096] 24 Second working chamber / Working chamber away from the piston rod

[0097] 26 Comfort Valve Body

[0098] 28 Comfort Valve

[0099] 30 Comfort Spring Washer Set

[0100] 32 Fastening components

[0101] 34 Enclosed Components

[0102] 36 Bottom Components

[0103] 38 Bottom Valve

[0104] 39 to the first fluid passage of the first working chamber 22

[0105] 40 to the second fluid passage of the second working chamber 24

[0106] 42 Spring elements

[0107] 44 Upper part of the shell

[0108] 45 Tubular portion

[0109] 46 End face / Closed face

[0110] 48 Drive Area

[0111] 50 Valve Area

[0112] 52 coils

[0113] 54 Damping valve device

[0114] 56 cover section

[0115] 58 Magnetic Isolation Section

[0116] 60 Armature Space

[0117] 62 Armature

[0118] 64 pole shoe tube

[0119] 65 armature

[0120] 66 holes

[0121] 68 Main Valve

[0122] 70 Pilot Valve

[0123] 72 Guide elements

[0124] 74 Preload Components

[0125] 76 Main Piston

[0126] 77. The central groove

[0127] 78 Main working chamber

[0128] 80 Housing components

[0129] 82a, b Springback / Compression Main Control Chamber

[0130] 84 Pilot Control Chamber

[0131] 86a, b Flow through sections

[0132] 90 Main valve seat

[0133] 92 Main Flow Channel

[0134] 94 Spring Components

[0135] 96a, b Flow throttling section

[0136] 98 Connection Channel

[0137] 100 Pilot Working Chamber

[0138] 102 Sliding Tape

[0139] 104a First pilot outflow channel

[0140] 104b Second pilot outflow channel

[0141] 110 Opening surface of the sliding tappet

[0142] 113 First Piston Region

[0143] 114 Second Piston Region

[0144] A S The first closing surface of the main piston 76

[0145] A D Compression opening face of main piston 76

[0146] A Z The springback opening surface of the main piston 76

[0147] A SP The second closing surface of the main piston 76

Claims

1. A shock absorber (10) for a motor vehicle, the shock absorber having an outer cylinder (12) and an inner cylinder (14) arranged coaxially with the outer cylinder, and a working piston (18) arranged axially within the inner cylinder (14), the working piston dividing the internal space of the inner cylinder (14) into a first working chamber (22) near the piston rod and a second working chamber (24) away from the piston rod. The damper has a damping valve device (54) having a coil (52), an armature (62) movable in the axial direction, and a main valve (68), the armature being arranged at least partially inside the coil (52), and the main valve having a main piston (76) that separates the compression main control chamber (82a) from the rebound main control chamber (82b). Its features are, A pre-tightening element (74) is provided, which abuts against the main piston (76) so that the pre-tightening element applies force to the main piston (76) in the opening direction of the main valve (68).

2. The vibration damper (10) according to claim 1, wherein, The preload element (74) is mounted on at least one stationary element (26; 72) of the damping valve device (54) by means of a fastening element (32).

3. The vibration damper (10) according to claim 2, wherein, The fastening element (32) is force-locked and / or form-locked connected to the stationary element (26; 72), especially by crimping.

4. The vibration damper (10) according to claim 2 or 3, wherein, The fastening element (32) is connected to the stationary element (26; 72) so that the fastening element can move in the axial direction without damage.

5. The vibration damper (10) according to any one of the preceding claims, wherein, The preload element (74) is constructed and abuts against the main piston (76) such that the main valve (68) is open in the operating state of the damper (10) in which the same pressure exists in each of the working chambers (22, 24).

6. The vibration damper (10) according to any one of claims 2 to 5, wherein, The damping valve device (54) includes a comfort valve (28), and the stationary element (26; 72) is part of the comfort valve (28).

7. The vibration damper (10) according to any one of the preceding claims, wherein, The preload element (74) includes a helical spring, a disc spring, or a spring washer.

8. The vibration damper (10) according to any one of the preceding claims, wherein, The preload element (74) has a first spring element (74a), a second spring element (74c), and a guide element (74b) connected to each of the spring elements.

9. The vibration damper (10) according to any one of the preceding claims, wherein, The fastening element (32) is cylindrical or annular in shape.

10. The vibration damper (10) according to claim 9, wherein, The stationary element (26; 72) has a centrally located hole (66), and the fastening element (32) is mounted in the hole (66).

11. The vibration damper (10) according to any one of the preceding claims, wherein, The main piston (76) separates the compression main control chamber (82a), the rebound main control chamber (82b), and the pilot control chamber (84) from each other. The damping valve device (54) has a pilot valve (70) configured to be circulated by hydraulic fluid during the rebound and compression phases. The pilot valve has a pilot working chamber (100) and a sliding tap (102) arranged in the pilot working chamber. The sliding tap is axially movable by means of the armature (62). The damping valve device (54) has a connecting channel (98) arranged between the pilot control chamber (84) and the pilot working chamber (100) and fluidly communicating the pilot control chamber and the pilot working chamber with each other.

12. A method for positioning a preload element (74) of a damper (10) according to any one of the preceding claims, wherein, The method includes the following steps: Place the preload element (74) onto the main piston (76); The fastening element (32) is pre-positioned on the stationary element (26, 72); A hydraulic fluid flow is applied to the damping valve device (54) of the shock absorber (10); The hydraulic pressure in the first working chamber (22) and the second working chamber (24) is continuously determined, and the pressure difference between the working chambers (22, 24) is continuously determined therefrom; Compare the determined pressure difference with the target value; When the determined differential pressure value deviates from the target value, the fastening element (32) is moved in the axial direction.

13. The method according to claim 12, wherein, The fastening element (32) is moved by means of a tool that can be operated manually or automatically.

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