Vibration damper with an adjustable damping valve device

Abstract

Vibration damper with an adjustable damping valve device (27), comprising an actuator (33) with a magnetic coil (41) that exerts a magnetic actuating force on an axially movable valve armature (43) within a sleeve-shaped, stationary return body (49), which comprises a conductive section (49L1) and an insulating section (49L), wherein the return body (49) interacts with a pole disk (57) that conducts a magnetic flux of the magnetic coil and at which an axial transfer of the magnetic flux for the adjusting movement of the valve armature (43) takes place, wherein the insulating section (49L) of the return body (49) is adjoined in the direction of the pole disk (57) by a second conductive section (49L2), and the valve armature (43) axially overlaps the second conductive section (49L2) depending on the stroke, characterized inthat the conductive section (49L1) and the insulating section (49l) of the return body (49) are seamless and the insulating section (49l) is formed by a cross-sectional reduction (49Q) of the return body (49) in the form of a groove on the outer circumference of the return body (49).

Description

[0001] The invention relates to a vibration damper with an adjustable damping valve device according to the preamble of patent claim 1.

[0002] DE 10 2013 218 658 A1 discloses a generic vibration damper whose damping valve device is adjustable by means of an electromagnetic actuator. The actuator comprises a magnetic coil that exerts a magnetic actuating force on a valve armature. The valve armature is guided axially movably in a return body. The return body comprises a base that forms a portion of a cover for the damping valve device. A sleeve section of the return body serves as a conductor for the magnetic flux of the magnetic coil. The sleeve section comprises a conductive section and an insulating section. The insulating section serves as a resistor and ensures a radial transfer of the magnetic flux from the conductive section of the return body to the valve armature.

[0003] An end of the insulating section of the return body opposite the base is axially connected to an annular, magnetically conductive pole disk. The insulating section extends radially between an outer step of the insulating section and a magnetically conductive housing part of the damping valve device.

[0004] In this variant, the insulating section is formed by a metallic sleeve that is firmly bonded to the conductive section, e.g., by soldering. The metallic sleeve can be made of stainless steel, for example.

[0005] An alternative design of an isolator within an adjustable damping valve device is known, for example, from DE 196 24 898 A1. An elastomer ring is used as the isolator. The same applies to DE 10 2011 003 054 A1.

[0006] In both DE 10 2013 218 658 A1 and DE 196 24 898 A1, an end of the valve armature pointing toward the pole disk always moves in the radial overlap area with the insulating section, regardless of the current flowing through the solenoid coil. This ensures that the entire magnetic flux flows through the valve armature and axially through the pole disk, which has direct contact with the conductive housing part.

[0007] In practice, this design principle results in constant displacement-force characteristics, which form a characteristic map with parallel constants depending on the current flowing through the solenoid coil. For this reason, return springs are often used in actuators, against which the magnetic force of the solenoid coil acts on the valve armature.

[0008] EP 3 409 984 A1 describes a vibration damper with an adjustable damping valve device, the return body of which is designed in three parts. Two opposing sections of the return body have a cutting edge geometry at the end, which together form a circumferential groove. Both sections are held together by an outer connecting sleeve, so that the groove runs along the inner diameter area with respect to the return body.

[0009] A very similar construction principle of the return body is implemented in DE 10 2006 014 463 A1.

[0010] The object of the present invention is to further develop the actuator of the damping valve device in such a way that the displacement-force characteristic curve has a positive gradient.

[0011] The problem is solved by the features of patent claim 1.

[0012] By combining an insulating section and a second conductive section, the magnetic flux of the solenoid coil can be influenced in a targeted manner to define the displacement-force function of the actuator. For ease of manufacture and uncritical durability, the conductive section and the insulating section of the return body are designed to be seamless. Seamless means homogeneous or one-piece. The groove is located on the outer circumference of the return body because an outer groove is easier to manufacture than an inner groove, and with an outer groove, there is no interruption within a guide surface on the return body for the valve armature.

[0013] In a further advantageous embodiment of the invention, the second conductive section of the magnetic return body has a magnetic conductivity that increases toward the pole disc. As the valve armature approaches the pole disc, the magnetic flux along this path would increase significantly. The second conductive section of the magnetic return body compensates for this magnetic flux by providing a parallel flow path for the magnetic flux.

[0014] Preferably, the second conductive section of the return body forms a magnetic flux path parallel to the pole disc to a housing part that conducts the magnetic flux. This configuration offers the advantage that the second conductive section of the return body does not require contact with the pole disc for its magnetic conduction function.

[0015] Furthermore, a transition region between the insulating section and the second conductive section of the return body has a cross-sectional increase in the direction of the second conductive section. Preferably, the cross-sectional increase is formed by a cone.

[0016] A complementary measure for influencing the force-displacement characteristic of the actuator is that the pole disc has an axial projection and the valve armature has an annular space to accommodate the projection as it approaches the pole disc. This creates an axial overlap between the valve armature and the pole disc, depending on the stroke position of the valve armature relative to the pole disc. This axial overlap leads to a radial magnetic flux, which also generates a vertical force component on the valve armature.

[0017] For this purpose, the axial projection of the pole disc is provided with a conical shape in the direction of the valve armature.

[0018] The invention will be explained in more detail with the help of the following description of the figures.

[0019] It shows: Fig. 1 Damping valve device on a vibration damper Fig. 2 Sectional view of the damping valve device

[0020] In Fig. 1, a vibration damper comprises a cylinder 1 in which a piston rod 3 is arranged for axial movement. A guide and sealing unit 7 guides the piston rod 3 out of the upper end of the cylinder. Within the cylinder 1, a piston unit 9 with a piston valve arrangement 11 is attached to the piston rod 3. The lower end of the cylinder 1 is closed off by a base plate 13 with a base valve arrangement 15. The cylinder 1 is enclosed by a container tube 17. The container tube 17 and an intermediate tube 5 form an annular space 19, which represents a compensation chamber. The space within the cylinder 1 is divided by the piston unit 9 into a first working chamber 21a and a second working chamber 21b. The working chambers 21a and 21b are filled with damping fluid. The compensation chamber 19 is filled with fluid up to the level 19a and with gas above.Within the compensation chamber 19, a first line section, namely a high-pressure section 23, is formed, which communicates with the second working chamber 21b via a bore 25 of the cylinder 1. This high-pressure section is followed by an adjustable damping valve device 27, mounted laterally on the container tube 17. A second line section, namely a low-pressure section 29, leads from this, see . Fig. 2, into the compensation chamber 19.

[0021] When the piston rod 3 extends upward from the cylinder 1, the upper working chamber 21b shrinks. An overpressure builds up in the upper working chamber 21b, which can only be released into the lower working chamber 21a through the piston valve assembly 11 as long as the adjustable damping valve 27 is closed.

[0022] When the adjustable damping valve device 27 is opened, fluid flows simultaneously from the upper working chamber 21b through the high-pressure section 23 and the adjustable damping valve device 27 into the compensation chamber 19. The damping characteristic of the vibration damper when the piston rod 3 is extended therefore depends on whether the adjustable damping valve device 27 is more or less open or closed.

[0023] When the piston rod 3 retracts into the cylinder 1, an overpressure builds up in the lower working chamber 21a. Fluid can flow upwards from the lower working chamber 21a through the piston valve arrangement 11 into the upper working chamber 21b. The fluid displaced within the cylinder 1 by the increasing piston rod volume is expelled through the base valve arrangement 15 into the compensation chamber 19. In the upper working chamber 21b, since the flow resistance of the piston valve arrangement 11 is lower than the flow resistance of the base valve arrangement 15, an increasing pressure also occurs. This increasing pressure can, when the damping valve device 27 is open, flow through the high-pressure section 23 into the compensation chamber 19.This means that when the damping valve device 27 is open, the vibration damper has a softer characteristic during retraction when the adjustable damping valve device 27 is open and a harder characteristic when the damping valve device 27 is closed, just as it does when the piston rod is extended. It should be noted that the flow direction through the high-pressure section 23 of the bypass is always the same, regardless of whether the piston rod is retracting or extending.

[0024] The Fig. Figure 2 shows the damping valve device 27 as an assembly. A magnetic actuator 33 for actuating a pre-stage valve 35 is arranged in a valve housing 31. The pre-stage valve 35 controls a main-stage valve 37 to generate the damping force. The basic design of the pre-stage valve and the main-stage valve is known, for example, from DE 10 2013 218 658 A1. The description of the valve design from DE 10 2013 218 658 A1 is also intended to be part of this description.

[0025] In this embodiment, the valve housing 31 is constructed in two parts. The pilot valve 35 and the main stage valve 37 are arranged in a lower valve housing 31U. A connecting piece 39 forms the connection between the high-pressure section 23 ( Fig. 1) and the main stage valve 37. The lower valve housing 31U is preferably welded to the reservoir tube 17. In principle, the damping valve device can also be used, for example, as an external unit or on the piston rod.

[0026] The magnetic actuator 33 is arranged in an upper valve housing 31O and comprises a magnetic coil 41 that exerts a magnetic actuating force on an axially movable valve armature 43. The valve armature 43 has an annular guide body 45 with a central axis 47, which the pre-stage valve 35 engages. The use of a pre-stage valve or compliance with a specific design of the main-stage valve are not mandatory for the invention.

[0027] The valve armature 43 is guided radially to a stationary, sleeve-shaped return body 49. A base 51 of the return body 49 closes a central opening 53 of the upper valve housing 310. Also arranged in the base 51 is a first bearing point 55 for the radial mounting of the axis 47 of the valve body 43.

[0028] The return body 49 interacts with an annular pole disk 57, which conducts a magnetic flux, symbolized by a dash-dot line, from the solenoid coil 41, at which an axial transfer of the magnetic flux takes place for the adjusting movement of the valve armature 43. The pole disk 57 has a second bearing point 59 for the axis 47 of the valve body 43 and forms an intermediate wall between the upper and lower valve housings 31U; 310.

[0029] The return body 49 comprises several functional sections. A first section 49L1, which conducts the magnetic flux, extends from the base 51 toward the pole disk 57. Regardless of the stroke position of the valve armature relative to the pole disk 57 or the first conductive section 49L1 of the return body 49, there is a large axial overlap between the first conductive section 49L1 and the valve armature 43, so that a high conductivity for the magnetic flux is always present in this area. The first conductive section 49L1 has a constant annular cross-section and thus a constant conductivity for the magnetic flux.

[0030] An insulating section 49l borders the first conductive section 49L1 of the return body 49. The insulating effect or the high resistance to a magnetic flux is achieved by the insulating section 49l being formed by a cross-sectional reduction 49Q of the return body 49. The cross-sectional reduction 49Q is formed, for example, by a circumferential groove formed on the outer circumference of the return body 49.

[0031] The insulating section 49l of the return body 49 is followed in the direction of the pole disk 57 by a second conductive section 49L2, so that a conductive section of the return body 49 is effective at both ends of the magnetic coil 41. As can be seen from the Fig. 2, the valve armature 43 comes into radial overlap with the second conductive section depending on the stroke.

[0032] The second conductive section 49L2 of the return body 49 does not have a cross-section over its entire length like the first conductive section 49L1, but has a magnetic conductivity that increases in the direction of the pole disk 57.

[0033] Furthermore, the Fig. 2 that the second conductive section 49L2 of the return body 49 forms a magnetic flux path 61 parallel to the pole disk 57 to a housing part conducting the magnetic flux, in the exemplary embodiment the lower valve housing 31U.

[0034] Despite the different functional sections 49L1; 49L; 49L2, the conductive section 49L1 and the insulating section 49L of the return body 49 are seamless. The second conductive section 49L2 is also integrally connected to the other two functional sections 49L1; 49L. Therefore, there is no integral connection between the sections 49L1; 49L2.

[0035] A transition region 49Ue between the insulating section 49l and the second conductive section 49L2 of the return body 49 in the direction of the second conductive section 49L2 again has an increase in cross-section in order to increase the magnetic conductivity within the return body 49. An increased magnetic conductivity in the second conductive section 49L2 results in a reduced magnetic flux passing between an end face 43S of the valve armature 43 and the pole disk 57, and thus a lower magnetic actuating force is also effective.

[0036] In addition to the second conductive section 49L2 on the return body 49, the actuator 33 has an axial projection 57V on the pole disk 57 as a further measure for influencing the travel-force characteristic curve. For this purpose, the valve armature 43 has an annular space 43R to accommodate the projection 57V when approaching the pole disk 57, so that, depending on the stroke position of the valve armature 43 relative to the pole disk 57, there is an axial overlap between the valve armature and the pole disk. The projection 57V on the pole disk 57 is not designed as a simple step, but has a conical shape in the direction of the valve armature 43. When the valve armature 43 approaches the conical projection 57V of the pole disk 57, a magnetic flux occurs at this point, which, however, only partially causes an axial actuating force on the valve armature 43.

[0037] The effective magnetic flux from the valve armature 43 to the pole disk 57 can be dimensioned via the relative axial position of the projection 57V on the pole disk 57 in the direction of the valve armature 43 to the axial position of the second conductive section 49L2 of the magnetic return body 49. The cone angle of the projection 57V and the profile at the transition area 49Ue also affect the characteristic curve of the actuator 33. The greater the axial overlap between the valve armature 43 and the second conductive section 49L2, the greater the proportion of magnetic flux along this path and the smaller the remaining proportion of magnetic flux between the valve armature 43 and the pole disk 57. Depending on the installation space for the valve armature, the magnetic return body, and the solenoid, the displacement-force characteristic curve can be practically horizontal or increase linearly or progressively by varying the aforementioned parameters. Reference symbol 1 cylinder 3 piston rod 5 Intermediate pipe 7 Guide and sealing unit 9 Piston unit 11 Piston valve arrangement 13 Base plate 15 Bottom valve arrangement 17 Container pipe 19 Annular space 21a / b Working Chamber 23 high-pressure section 25 bore 27 Damping valve device 29 Low-pressure section 31 valve housing 31O upper valve housing 31U lower valve housing 33 Actuator 35 pre-stage valve 37 Main stage valve 39 connecting pieces 41 Solenoid coil 43 valve anchor 43R Annular space in the valve armature 43S Front side of the valve armature 45 guide bodies 47 Axis of the valve armature 49 Return body 49l insulating section of the return body 49L1 first conductive section of the return body 49L2 second conductive section of the return body 49Q Cross-section reduction at the return body 49Ue transition area at the return body 51 Bottom of the return body 53 Opening in the upper valve housing 55 first storage location 57 Pole disc 57V projection on the pole disc 59 second storage location 61 Magnetic flux path

Claims

[1] Vibration damper with an adjustable damping valve device (27), comprising an actuator (33) with a magnetic coil (41) which exerts a magnetic actuating force on an axially movable valve armature (43) within a sleeve-shaped, stationary return body (49) comprising a conductive section (49L1) and an insulating section (49L), wherein the return body (49) interacts with a pole disk (57) conducting a magnetic flux of the magnetic coil, at which an axial transfer of the magnetic flux for the adjusting movement of the valve armature (43) takes place, wherein the insulating section (49L) of the return body (49) is adjoined in the direction of the pole disk (57) by a second conductive section (49L2), and the valve armature (43) comes into axial overlap with the second conductive section (49L2) depending on the stroke, characterized bythat the conductive section (49L1) and the insulating section (49l) of the return body (49) are seamless and the insulating section (49l) is formed by a cross-sectional reduction (49Q) of the return body (49) in the form of a groove on the outer circumference of the return body (49). [2] Vibration damper according to claim 1, characterized by that the second conductive section (49L2) of the return body (49) has a magnetic conductivity that increases in the direction of the pole disc (57). [3] Vibration damper according to at least one of claims 1 or 2, characterized by that the second conductive section (49L2) of the return body (49) forms a magnetic flux path (61) parallel to the pole disc (57) to a housing part (31U) conducting the magnetic flux. [4] Vibration damper according to at least one of claims 1 to 3, characterized bythat a transition region (49Ue) between the insulating section (49l) and the second conductive section (49L2) of the return body (49) has an increase in cross-section in the direction of the second conductive section (49L2). [5] Vibration damper according to at least one of claims 1 to 4, characterized by that the pole disc (57) has an axial projection (57V) and the valve armature (43) has an annular space (43R) for receiving the projection (57V) when approaching the pole disc (57), so that depending on the stroke position of the valve armature (43) relative to the pole disc (57), there is an axial overlap between the valve armature (43) and the pole disc (57). [6] Vibration damper according to claim 5, characterized by that the axial projection (57V) of the pole disc (57) has a conical shape in the direction of the valve armature (43).

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