Vibration damper with an adjustable damping valve device

Abstract

Vibration damper with an adjustable damping valve assembly, comprising a main stage valve and a pre-stage valve with an annular pre-stage valve body for controlling the main stage valve, wherein the pre-stage valve determines the pressure level in a control chamber located behind an annular main stage valve body, wherein a multi-part annular housing of the adjustable damping valve assembly forms a piston rod guide for a piston rod axially movable in a working cylinder, wherein the housing comprises a cover, an intermediate housing and a base part, wherein the control chamber is spatially separated from the pre-stage valve body by means of an intermediate wall.

Description

The invention relates to a vibration damper with an adjustable damping valve device according to the preamble of claim 1.DE 40 24 920 A1 discloses, in the embodiment according to FIG. 11, a vibration damper of the generic type, the adjustable damping valve device of which is arranged in the region of a piston rod guide of the vibration damper or is even a component of the piston rod guide.The variable damping valve device includes a solenoid coil that exerts a lift force on an annular pilot valve body against a return spring. The pre-stage valve body forms with a rear side of a main stage valve body a control chamber, the pressure force of which represents a closing force on the main stage valve body. The main stage valve body is a flexible valve disk which is braced on the inside diameter between an upper housing part and a lower housing part. The clamping force is generated by a container tube which is crimped on the edge and presses the housing of the damping valve device onto an end face of a working cylinder.Overall, this damping valve device is distinguished by its very simple construction, but the design of the main stage valve restricts the selection of the valve disk as a main stage valve body, so that the possible damping force characteristic curves are also limited by this.The object of the present invention is to provide a variable damping valve device which enables a broader spectrum of damping force characteristics.According to the invention, the object is achieved in that the housing comprises a cover, an intermediate housing and a base part, wherein the control chamber is spatially separated from the pre-stage valve body by means of an intermediate wall.On account of the multi-part nature of the housing of the damping valve device and the use of an intermediate wall, there is, on the one hand, a clearly improved force flow when the damping valve device is axially braced between a container tube and a working cylinder. Regardless of this design of the vibration damper, the intermediate wall simplifies the structural design of, in particular, the main stage valve, whose main stage valve body now no longer necessarily has to be designed as an elastic disk, as described with respect to the prior art.In a further advantageous embodiment, the intermediate wall has a plurality of axially raised precursor valve seat surfaces, between which an equal distance angle is present in the circumferential direction. The individual pre-stage valve seat surfaces simplify the dimensioning of the lifting forces acting on the pre-stage valve body by varying the number and the cross sections of the control pressure channels framed by the pre-stage valve seat surfaces. The uniform distribution of the control pressure channels prevents a skew when the flow against the pre-stage valve body is increased.According to an advantageous dependent claim, the intermediate wall has an axial guide section which delimits the control chamber and forms a guide surface for the main stage valve body. In principle, the main stage valve body could also slide on a guide surface, e.g. connected to the base part. However, the base part may be subjected to transverse forces. This influence is excluded by this separation of the component via the intermediate wall.It is provided that the intermediate wall and an axial sleeve for an armature of the pre-stage valve are configured in one piece. This simplifies the angular orientation of both sections of the intermediate wall, whereby the functional reliability of the pre-stage valve is improved.With regard to a manageable structural unit of the damping valve device during the assembly phase, the sleeve of the intermediate wall and the cover of the housing are connected to one another. The connection is preferably designed as a press fit.In order that the housing of the damping valve device can perform the function of a piston rod guide as optimally as possible, the base part of the housing has a guide sleeve which extends axially in the direction of the cover as far as beyond the intermediate wall. This increases the guide length of the housing or of the piston rod guide for the piston rod.With regard to transverse force isolation, a movement gap is present between the sleeve of the intermediate wall and the guide sleeve of the base part.With regard to a defined magnetic flux on the pre-stage valve, the sleeve of the intermediate wall is connected to a guide ring which is contacted on the housing of the damping valve device within a magnetic flux of a magnetic coil for controlling the pre-stage valve. A second magnetic flux via the cover onto the guide sleeve of the base part can thereby be prevented.Furthermore, it can be provided that a flow connection between a working chamber on the piston rod side in the working cylinder and a compensating chamber through the main stage valve has a check valve opening in the flow direction to the compensating chamber.In one embodiment, the opening nonreturn valve is hydraulically connected in series upstream of the main stage valve in the flow direction starting from the working chamber on the piston rod side. This valve arrangement effectively prevents a backflow proceeding from the compensating chamber of the vibration damper through the damping valve device into the working chamber on the piston rod side and, given a corresponding design, allows the nonreturn valve to contribute a significant damping force by forming a type of pilot valve for the adjustable damping valve device.Alternatively or in combination, the opening nonreturn valve can be arranged hydraulically in series downstream of the main stage valve in the flow direction starting from the working space on the piston rod side. In this construction, no gas can enter the adjustable damping valve starting from the compensating chamber.Preferably, the check valve, in particular the closing spring of the check valve, is supported on the guide section of the intermediate wall. As a result, the operating force and the operating position of the check valve are independent of the setting of the pre-stage valve and thus also of the main stage valve.The invention will be explained in more detail with reference to the following description of the figures.It shows: FIG. 1 is a schematic illustration of the vibration damper FIG. 2 shows a detailed illustration of the damping valve device according to FIG. 2. 1FIG. 1 shows a schematic illustration of a vibration damper 1 with an adjustable damping valve device 3 within a piston rod guide 5 as the end termination of a working cylinder 7 filled with damping medium. The damping medium displaced from the working chambers 13; 15 is accommodated by a compensating chamber 17 which is at least partially filled with damping medium. The piston is equipped with valves 19; 21 of different function. This different function is emphasized by a styled spring.A bottom valve body 23 at an end of the working cylinder 7 opposite the piston rod guide 5 likewise has two valves 25; 27 with different functions. A damping valve 25 within the base valve body serves in particular as a pressure limiting valve, whereas the valve 27 provides a check valve during a piston rod extension movement for the inflow of damping medium from the compensating chamber 17 into the working chamber 15 remote from the piston rod.The valves 19; 21 in the piston 11 are designed in principle to be similar. A check valve 19 in the piston 11 opens upon a retraction movement of the piston rod 9, so that the damping medium displaced by the piston rod 9 from the working chamber 15 remote from the piston rod flows through the check valve 19 into the working chamber 13 on the piston rod side and further through the adjustable damping valve device 3 into the compensating chamber 17. The pressure limiting valve 25 remains closed up to a limit pressure in the working chamber 15 remote from the piston rod. If this limit pressure is exceeded, the pressure limiting valve 25 opens and a direct outflow into the compensating chamber 17 is free.During an extension movement of the piston rod, the check valve 19 in the piston 11 is closed. The valve designed as a pressure limiting valve 21 is also closed below a limit pressure. Consequently, the entire damping medium volume within the annular working chamber 13 on the piston rod side is displaced by the adjustable damping valve device 3 into the compensating chamber 17. Thus, with a single damping valve device 3, the damping force for two working directions of the vibration damper 1 can be influenced. The damping valve device 3 is always flowed through only in one direction starting from the working chamber 13 on the piston rod side.FIG. 2 shows a detail of the vibration damper 1 according to FIG. 1 in a concrete construction. The adjustable damping valve device 3 arranged in the piston rod guide 5 comprises a magnetic coil 29 and a magnet armature 31 as actuator for a pre-stage valve 33 with an annular pre-stage valve body for controlling a main stage valve 35. However, it is also possible for the magnet armature and the pre-stage valve body to be separate components.The pilot-stage valve 33 is actuated by determining the pressure level in a control chamber 39 on the rear side of an annular main-stage valve body 37 with respect to the inflow from the working chamber 13 on the piston rod side. The pressure in the control chamber 39 represents a closing force acting on the main stage valve body 37.A multipart annular housing of the adjustable damping valve device 3 forms the piston rod guide 5 for the piston rod 9 that is axially movable in the working cylinder 7. the housing 5 of the damping valve device 3 or the piston rod guide comprises a cover 41, an intermediate housing 43 and a base part 45. the housing 5 is axially braced between a flanged edge 47 of an outer container tube 49 and the working cylinder 7. The working cylinder 7 is centered radially on a shoulder of the base part 45. the intermediate housing 43 and the cover 41 bear radially on the container tube 49. The cover 41 carries a piston rod seal 51 in the region of a passage opening for the piston rod 9, and a seal 53 is optionally chambered on the outer periphery of the cover 41, which seal is intended to prevent the escape of damping medium and / or gas from the compensating space 17 as the last barrier.In addition to the cover 41, the intermediate housing 43 and the base part 45, the housing 5 comprises an intermediate wall 55. the intermediate wall 55 spatially separates the main stage valve 35 from the pre-stage valve 33, in particular the control chamber 39, from the pre-stage valve body 31.The intermediate wall 55 has a plurality of axially raised precursor valve seat surfaces 57, between which an equal distance angle is present in the circumferential direction. Basically, the main stage valve body 37 can slide on the base part 45. The intermediate wall 55 preferably has an axial guide section 59 which delimits the control chamber 39 radially inward and forms a guide surface for the main stage valve body 37.Further, the intermediate wall 55 and an axial sleeve 61 for the pilot valve body 31 are integrally formed. The sleeve 61 of the intermediate wall 55 is in turn connected to a guide ring 63 which is in contact with the housing 5 of the damping valve device 3 within a magnetic flux of the magnetic coil 29 for controlling the pre-stage valve 33. This produces a staircase-like cross-section at the intermediate wall 55. The sleeve 61 of the intermediate wall 55 and the cover 41 of the housing 5 are connected to one another. As a result, the entire component "intermediate wall" is axially fixed within the damping valve device. In addition, inner and outer seals 65; 67 may prevent the outflow of damping medium from the precursor valve along the lid 41. The cover 41 preferably forms a magnetic resistance so that the magnetic flux from the solenoid coil takes the optimum course through the pre-stage valve body 31. Alternatively, a magnetic resistance would be conceivable between the cover 41 and the base part 45, for exampleThe base part 45 of the housing 5 has a guide sleeve 69, which extends axially in the direction of the cover 45 as far as beyond the intermediate wall 55. Between guide section 59 of intermediate wall 55 and guide sleeve 69 of the base part, there is a movement gap 70 which isolates an elastic movement of guide sleeve 69 with respect to guide section 59 of intermediate wall 55. Here too, a seal 71 can be provided in order to prevent leakage past the pre-stage valve 33. Between the cover 41 and an end shoulder of the guide sleeve 69, a bearing bush 73 is arranged. As a result, a large guide length is present for the piston rod 9 over the very large distance of the piston 11 from the bearing bush 73.A flow connection 75 is provided for the connection of the pre-stage valve 33 and the main stage valve 35 to the working chamber 13 on the piston rod side and to the compensating chamber 17, which flow connection has at least one check valve 77; 79.An opening nonreturn valve 77 in the flow direction, starting from the working chamber 13 on the piston rod side to the compensating chamber 17, is connected hydraulically in series upstream of the main stage valve 35. This check valve 77 can be dimensioned with a very low opening force if the aim is that no gas and / or damping medium should flow from the compensating chamber 17 through the main stage valve 35 into the working chamber 13 on the piston rod side. However, this check valve 77 can also be provided with an appreciable opening force so that the check valve 77 is always effective as an additional passive damping valve. The check valve 77 is designed as a seat valve, the valve seat surface of which is designed on the base part 45. A closing spring 89 of the check valve 77 is supported on an end face of the stationary guide section 59 of the intermediate wall 55. As a result, the operating behavior of the check valve 77 is independent of the operating behavior of the main stage valve body 37, which due to the spatial proximity could also serve as a support element for the closing spring.If only the return flow of gas and / or damping medium from the compensating chamber 17 into the working chamber 13 on the piston rod side is to be prevented, then an opening nonreturn valve 79 can be arranged hydraulically in series downstream of the main stage valve 35 in the flow direction starting from the working chamber 13 on the piston rod side.When the adjustable damping valve device flows against it from the working chamber 13 on the piston rod side, the optional nonreturn valve 77 opens, as a result of which the lower side of the main stage valve body 37 pointing in the direction of the nonreturn valve 77 is acted upon by damping medium via at least one connection opening in the base part 45 as part of the flow connection 75. The main stage valve body 37 has at least one control opening 81 which connects the control chamber 39 to the underside of the main stage valve body 37. From the control chamber 39, however, damping medium can escape via an outflow channel 85 into the compensating chamber 17 via outflow openings 83 framed by the pre-stage valve seat surfaces 57, depending on the stroke position of the pre-stage valve body 31. From the cooperation of the inflow of the main stage valve body 37 and the outflow cross section at the outflow openings 83 set via the pre-stage valve 33, a closing pressure is established in the control chamber 39, which exerts a defined closing force on the main stage valve body 37. Between a main stage valve seat surface 87 and the main stage valve body 37 lifted therefrom, the damping medium can flow off into the compensating chamber 17 while simultaneously generating a damping force.Reference numerals denote reference numerals1 Vibration damper 3 Adjustable damping valve device 5 Piston rod guide / housing of the adjustable damping valve device 7 Working cylinder 9 Piston rod 11 Piston 13 Piston rod-side working chamber 15 Working chamber 17 Compensating chamber 19 Nonreturn valve 21 Pressure limiting valve 23 Base valve body 25 Pressure limiting valve 27 Nonreturn valve 29 Magnetic coil 31 Magnet armature 33 Preliminary stage valve 35 Main stage valve 37 Main stage valve body 39 Control chamber 41 Cover 43 Intermediate housing 45 Base part 47 Edge of the container tube 49 Container tube 51 Piston rod seal 53 Seal 55 Intermediate wall 57 Preliminary stage valve seat surface 59 Guide portion 61 Sleeve 63 Guide ring 65 Inner seal 67 Outer seal 69 Guide sleeve 70 Movement gap 71 Seal 73 Bearing bush 75 Flow connection 77 Nonreturn valve 79 Nonreturn valve 81 Control opening 83 Outflow opening 85 Outflow channel 87 Main stage valve seat surface 89 Closing spring of the nonreturn valveReferences included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedDE 40 24 920 A1

[0002]

Claims

Vibration damper (1) with an adjustable damping valve device (3) comprising a main stage valve (35) and a pre-stage valve (33) with an annular pre-stage valve body (31) for controlling the main stage valve (35), in that the pre-stage valve (33) determines the pressure level in a control chamber (39) at the rear side of an annular main stage valve body (37), wherein a multipart annular housing (5) of the adjustable damping valve device (3) forms a piston rod guide for a piston rod (9) which is axially movable in a working cylinder (7), characterized in that the housing (5) comprises a cover (41), an intermediate housing (43) and a base part (45), wherein the control chamber (39) is spatially separated from the pre-stage valve body (31) by means of an intermediate wall (55).Vibration damper (1) according to Claim 1, characterized in that the intermediate wall (55) has a plurality of axially raised pre-stage valve seat surfaces (57), between which there is an equal distance angle in the circumferential direction.Vibration damper (1) according to either of Claims 1 and 2, characterized in that the intermediate wall (55) has an axial guide portion (59) which delimits the control space (39) and forms a guide surface for the main stage valve body (37).Vibration damper (1) according to at least one of Claims 1 to 3, characterized in that the intermediate wall (55) and an axial sleeve (61) for an armature of the pre-stage valve (33) are designed in one piece.Vibration damper (1) according to Claim 4, characterized in that the sleeve (61) of the intermediate wall (55) and the cover (41) of the housing (5) are connected to one another.Vibration damper (1) according to at least one of Claims 1 to 5, characterized in that the base part (45) of the housing (5) has a guide sleeve (69) which extends axially in the direction of the cover (41) as far as beyond the intermediate wall (55).Vibration damper (1) according to Claim 6, characterized in that a movement gap (70) is present between the sleeve (61) of the intermediate wall (55) and the guide sleeve (69).Vibration damper (1) according to at least one of Claims 4 to 7, characterized in that the sleeve (61) of the intermediate wall (55) is connected to a guide ring (63), which is in contact with the housing (5) of the damping valve device (3) within a magnetic flux of a magnetic coil (29) for controlling the pre-stage valve (33).Vibration damper (1) according to at least one of Claims 1 to 8, characterized in that a flow connection (75) between a working chamber (13) on the piston rod side in the working cylinder (7) and a compensating chamber (17) through the main stage valve (35) has a nonreturn valve (77; 79) which opens in the flow direction to the compensating chamber (17).Vibration damper (1) according to Claim 9, characterized in that the opening nonreturn valve (77) is connected hydraulically in series upstream of the main stage valve (35) in the flow direction starting from the working chamber (13) on the piston rod side.Vibration damper (1) according to Claim 9, characterized in that the opening nonreturn valve (79) is arranged hydraulically in series downstream of the main stage valve (35) in the flow direction, starting from the working chamber (13) on the piston rod side.Vibration damper (1) according to Claim 9, characterized in that the nonreturn valve (77) is supported on the guide section (59) of the intermediate wall (55).

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