# Patent

## Title
Regulated dashpot with shock-absorption force controls

## Abstract

A regulable dashpot with shock-absorption force controls, especially intended for motor vehicles, with at least one flow-regulating system including one or more shock-absorption components for the compression phase and/or for the decompression phase. The object is to allow the dashpot to shift continuously between the hard and soft phases, whereby the valve-adjustment intervals can be varied at intervals that are not unnecessarily short or even unattainable. At least one valve assembly is accordingly supplied with variable flow impedance by a regulating valve (5 or 6).

## Background
BACKGROUND OF THE INVENTION
The present invention concerns a regulated dashpot with shock-absorption force controls, especially intended for motor vehicles.
Regulated hydraulic dashpots with flow-regulating system that shift back and forth between compression and decompression phases in operation are known. Dashpots of this genus are described in German 3 803 838 C2 for instance.
There is a drawback to such dashpots in that their design permits them to shift only suddenly between the hard and soft phases, limiting the range of control. The comfortability of the ride can be increased only to a limited extent.
The object of the present invention is accordingly a dashpot of the aforesaid genus that can shift continuously between the hard and soft phases, whereby the valve-adjustment intervals can be varied at intervals that are not unnecessarily short or even unattainable.
SUMMARY OF THE INVENTION
The present invention has many advantages. A continuous transition between hard and soft phases can be obtained by simple means. Valve-adjustment intervals can be maintained long enough to allow the device to be manufactured at justifiable component costs and to be operated at low requisite adjustment powers.
One particular advantage is that the flow-regulating system can be modular and employed in different vehicles with various shock-absorption performances. Since there will be no sudden jolts when shifting between the hard and soft phases and vice versa, riding comfort will be considerably improved.



BRIEF DESCRIPTION OF THE DRAWINGS 
Various embodiments of the present invention will now be specified by way of example with reference to the accompanying drawing, wherein
FIG. 1 is a schematic illustrating how a dashpot can be regulated in accordance with a single-chamber principle,
FIGS. 2 through 11 are schematics illustrating various other approaches to regulation in accordance with the single-chamber principle,
FIGS. 12 and 13 are schematics illustrating how a dashpot can be regulated in accordance with a resilient-chamber principle and with a two-chamber principle, and
FIG. 14 is a schematic illustrating regulation inside a dashpot cylinder.



DESCRIPTION OF THE PREFERED EMBODIMENTS
The figures illustrate hydraulic circuitry specific to various dashpots. Each dashpot includes a piston 3 mounted on the end of a piston rod 2 and traveling back and forth inside a cylinder 1. A reservoir 4 contains a compressed gas that compensates for the volume of hydraulic fluid displaced by piston 3. Reservoir 4 can be integrated into the dashpot.
FIG. 1 illustrates the hydraulic circuitry for a dashpot in accordance with the present invention. The dashpot includes two hydraulically parallel regulating valves 5 and 6. Hydraulically paralleling both regulating valves 5 and 6 is a very narrowly constricted bypass valve 7, which can alternatively be integrated into one or both regulating valves. Bypass valve 7 provides a minimal passage for the hydraulic fluid and accordingly prevents the dashpot from being entirely blocked while regulating valves 5 and 6 are closed. When closed, regulating valves 5 and 6 provide continuous regulation of the two phases and, when closed, allow the fluid to flow. Regulating valve 5 regulates the flow while piston 3 is traveling in the compression direction and regulating valve 6 regulates it while the piston is traveling in the decompression direction. The rate of flow depends on the one hand on the difference between the pressure in an upper chamber 8 and that in a lower chamber 9, the two chambers being separated by piston 3, and on the other hand on the cross-section of the passage through regulating valves 5 and 6 as dictated by flow controls like those known from German Patent 10 040 518.
FIG. 2 illustrates another embodiment of the circuitry illustrated in FIG. 1. In this embodiment, fluid can flow through both regulating valves 5 and 6 from either end as long as they are open, and the operative direction is prescribed by external checkvalves 10 and 11.
FIG. 3 illustrates an advanced version of the circuitry illustrated in FIG. 2. It employs spring-loaded checkvalves 12 and 13 instead of the external checkvalves 10 and 11. Such checkvalves will open to an extent that depends on the difference in pressure between chambers 8 and 9. The type of springs employed determine the intended performance curve of the dashpot in both compression and the decompression phases.
FIG. 4 illustrates an advanced version of the circuitry illustrated in FIG. 3. It includes a valve assembly 18 comprising unregulated spring-loaded checkvalves 16 and 17 that parallel regulated spring-loaded checkvalves 12 and 13. Checkvalves 16 and 17 parallel each other hydraulically and operate independently in both the compression and the decompression phases. Valve assembly 18 can be integrated into piston 3 and acts as a standard spring loaded piston. The performance curve for valve assembly 18 is set to “hard” and that of regulated spring-loaded checkvalves 12 and 13 to “soft”. Regulating valves 5 and 6 can accordingly now switch independently of each other and continuously back and forth between hard and soft in both the compression and the decompression phases. In addition to bypass valve 7, bypass valves 19 and 20 can be introduced paralleling spring-loaded checkvalves 12 and 13.
This embodiment ensures constantly reliable driving performance even when the electricity or electronics fail. In such an event, regulating valves 5 and 6 will substantially close, and continued operation of the dashpot will be ensured by the mechanical action of the spring-loaded checkvalves 16 and 17 in valve assembly 18 at a hard performance curve, preferably within piston 3, that is.
The embodiment illustrated in FIG. 5 lacks the regulated spring-loaded checkvalves 12 and 13 employed in the embodiment illustrated in FIG. 4. This embodiment is an advanced version of the regulable dashpot illustrated in FIG. 1, employing a parallel valve assembly 18 like that in the version illustrated in FIG. 4. The bypass valve can also be eliminated.
FIG. 6 illustrates an alternative to the embodiment illustrated in FIG. 5. Paralleling a valve assembly 18 that comprises unregulated spring-loaded checkvalves 16 and 17 with their hard performance curve are two similar spring-loaded checkvalves 12 and 13 with a soft performance curve. Checkvalves 12 and 13 can be brought into play by way of associated hydraulic switches 21 and 22, allowing a soft performance curve to be introduced while piston 3 is traveling in either the compression or the decompression direction. Paralleling these are two parallel one-way checkvalves 23 and 24 with a soft performance curve that can be actuated and regulated by a regulating valve 25. This circuitry again allows the shock-absorption performance curves to be established anywhere between hard and soft independently of each other as desired with the piston traveling in either direction.
Circuitry similar to that illustrated in FIG. 6 can be attained as illustrated in FIG. 7. The soft checkvalves 12 and 13 in this embodiment are provided with a two-to-three way valve 26 instead of two individual switching valves.
FIG. 8 illustrates another alternative embodiment. A valve assembly 27 comprises two spring-loaded checkvalves 28 and 29, each permitting the flow in a direction opposite that of the other. Checkvalves 28 and 29 have a soft performance curve and are alternately controlled by a two-to-three way valve 30. A flow-regulating valve 31 continuously opens or closes a parallel hydraulics line 32. A constricted bypass valve 33 ensures minimal unimpeded flow.
FIG. 9 illustrates an advanced version of the of the embodiment illustrated in FIG. 8. Upstream of flow-regulating valve 31 is a valve assembly 34 comprising two spring-loaded opposed-flow checkvalves 35 and 36. Checkvalves 35 and 36 also have a soft performance curve, although this curve can be varied between hard and soft. Bypass valve 33, which, like the one illustrated in
FIG. 8, can parallel flow-regulating valve 31, two-to-three way valve 30, and/or the two series comprising a regulation-and-switching valve and checkvalves 35 and 36 or checkvalves 28 and 29, again ensures minimal flow as long as two-to-three way valve 30 and flow-regulating valve 31 are closed.
FIG. 10 also illustrates an advanced version of the embodiment illustrated in FIG. 8. This version includes, paralleling the components illustrated in FIG. 8, another, unregulable, valve assembly 37 comprising spring-loaded opposed-flow checkvalves 38 and 39. Checkvalves 38 and 39 have a hard performance curve and can preferably be integrated into the piston in the form of standard cupspring-loaded valves.
FIG. 11 illustrates another advanced version of the embodiment illustrated in FIG. 8. It includes a valve assembly 27 comprising spring-loaded opposed flow checkvalves 28 and 29 with a soft performance curve, their direction of flow being reversed by a two-to-three way valve 30. The flow-regulating valve 31 in this embodiment, however, parallels valve 30, constantly maintaining the valve assembly 27 comprising checkvalves 28 and 29 in series with the latter. This embodiment also includes a constricted bypass valve 33 that ensures minimal flow.
The flow-regulating assembly 40 represented by the dot-and-dash lines in FIGS. 1 through 11 is depicted in the form of a preferably self-contained block 41 in FIGS. 12 and 13. Flow-regulating block 41 can also communicate with valve assembly 18, 27, 34, or 37.
The flow-regulating block 41 represented in FIG. 12 is hydraulically interposed between lower cylinder chamber 9 and pressure-compensating gas reservoir 4.
FIG. 13 illustrates a double-cylinder dashpot with a valve assembly 42 comprising two spring-loaded checkvalves 43 and 44 integrated into its piston 3. A bottom valve 46 in the form of a spring-loaded one-way valve is interposed between lower cylinder chamber 9 and a pressure-compensating reservoir represented by the space 45 between the cylinder's walls. The flow regulating assembly is preferably again in the form of a self-contained block 41 located outside the dashpot and hydraulically interposed between cylinder chambers 8 and 9.
The hydraulic switching-and-regulating components in the embodiment illustrated in FIG. 14 are integrated, like the components illustrated in FIG. 11, into the dashpot's piston 3.
LIST OF PARTS


    1. cylinder
    2. piston rod
    3. piston
    4. reservoir
    5. regulating valve
    6. regulating valve
    7. constricted bypass valve
    8. upper cylinder chamber
    9. lower cylinder chamber
    10. checkvalve
    11. checkvalve
    12. checkvalve
    13. checkvalve
    14. compression spring
    15. compression spring
    16. checkvalve
    17. checkvalve
    18. valve assembly
    19. constricted bypass
    20. constricted bypass
    21. hydraulic switch
    22. hydraulic switch
    23. checkvalve
    24. checkvalve
    25. flow-regulating valve
    26. two-to-three way valve
    27. valve assembly
    28. checkvalve
    29. checkvalve
    30. two-to-three way valve
    31. flow-regulating valve
    32. hydraulics line
    33. constricted bypass valve
    34. valve assembly
    35. checkvalve
    36. checkvalve
    37. valve assembly
    38. checkvalve
    39. checkvalve
    40. flow-regulating assembly
    41. flow-regulating block
    42. valve assembly
    43. checkvalve
    44. checkvalve
    45. intermural space
    46. bottom valve

## Claims

1. A regulated dashpot with shock-absorption force controls, for motor vehicles, comprising: at least one flow-regulating system including at least one shock-absorption component for a compression phase and for a decompression phase; at least one valve assembly with electrically variable flow resistance regulated by a regulating valve; at least one fixed bypass valve with a non-varying constricted flow cross-section hydraulically and directly paralleling the flow-regulating system, whereby said fixed bypass valve has a constant opened flow-through cross-section hydraulically in parallel with said regulating valve; said at least one flow regulating system for the compression phase and said at least one flow regulating system for the decompression phase being in the form of said regulating valve with variable flow constriction, said flow resistance being continuous for providing continuous damping between soft and hard damping, said bypass valve preventing pressure pulses in damping fluid when said regulating valve transfer rapidly from open to close positions corresponding to upward wheel shocks and sudden wheel accelerations, so that sudden jolts are prevented when shifting between soft and hard damping for comfort in riding in said vehicles, said fixed bypass valve being integratable into said flow-regulating system and having minimal passage for hydraulic fluid and preventing the dashpot from being entirely blocked when said regulating valve is closed, said flow-regulating system for the compression and decompression phases forming main flow channels through said shock-absorption component, said valve assembly with electrically variable flow resistance forming a main valve assembly for said shock-absorption component, said fixed bypass valve having a constant non-adjustable flow cross-section.

2. A dashpot as defined in claim 1, wherein said flow-regulating system and said flow-shock-absorption component are accommodated in a separate unit in form of a flow regulating block outside the dashpot and communicating with said dashpot through hydraulic-fluid lines.

3. A regulated dashpot as defined in claim 1, wherein said flow regulating system comprises two hydraulically parallel regulating valves, said bypass valve being hydraulically in parallel with said two regulating valves and having minimal passage for hydraulic fluid for preventing the dashpot from being entirely blocked while said regulating valves are closed.

4. A regulated dashpot with shock-absorption force controls, for motor vehicles, comprising: at least one flow-regulating system including at least one shock-absorption component for a compression phase and for a decompression phase; at least one valve assembly with electrically variable flow resistance regulated by a regulating valve; at least one fixed bypass valve with a non-varying constricted flow cross-section hydraulically and directly paralleling the flow-regulating system, whereby said fixed bypass valve has a constant opened flow-through cross-section hydraulically in parallel with said regulating valve; said at least one flow regulating system for the compression phase and said at least one flow regulating system for the decompression phase being in the form of said regulating valve with variable flow constriction, said flow resistance being continuous for providing continuous damping between soft and hard damping, said bypass valve preventing pressure pulses in damping fluid when said regulating valve transfer rapidly from open to close positions corresponding to upward wheel shocks and sudden wheel accelerations, so that sudden jolts are prevented when shifting between soft and hard damping for comfort in riding in said vehicles, said fixed bypass valve being integratable into said flow-regulating system and having minimal passage for hydraulic fluid and preventing the dashpot from being entirely blocked when said regulating valve is closed, said flow-regulating system and said flow-shock-absorption component being accommodated in a separate unit in form of a flow regulating block outside the dashpot and communicating with said dashpot through hydraulic-fluid lines; said flow regulating system comprising two hydraulically parallel regulating valves, said bypass valve being hydraulically in parallel with said two regulating valves and having minimal passage for hydraulic fluid for preventing the dashpot from being entirely blocked while said regulating valves are closed.