HYDROPNEUMATIC SUSPENSION COMPONENT

Abstract

The invention relates to a hydropneumatic suspension component such as a gas charged damper. The invention further relates to a floating piston for a hydropneumatic suspension component. Uses of adsorbent material and/or open-cell foam are also disclosed.

Claims

1. A hydropneumatic suspension component comprising: a variable-volume chamber having a first portion volume for holding a pressurised gas and a separate second portion volume for holding a non-gaseous fluid used as a damping medium, wherein the first portion volume is isolated from the non-gaseous fluid in the second portion volume, and further wherein the first portion volume comprises a mass of an adsorptive material and/or an open-cell foam to limit the build-up of pressure as the first portion volume is compressed in use by the non-gaseous fluid provided in the second portion volume.

2. The hydropneumatic suspension component according to claim 1, wherein the adsorptive material is activated carbon.

3. The hydropneumatic suspension component according to claim 1, wherein the adsorptive material is in a loose granular form, and is provided in combination with an open cell foam and/or a fine gauze.

4. The hydropneumatic suspension component according to claim 1, wherein the open cell foam is treated with an oleophobic coating, or comprises intrinsic oleophobic qualities.

5. The suspension component according to claim 1, wherein the adsorptive material is in the form of a self-supporting element or monolith comprising granules bound together using a binder.

6. The hydropneumatic suspension component according to claim 1, in which the first portion volume is isolated from the non-gaseous fluid in the second portion volume by an element selected from a moveable member comprising a floating piston or a flexible divider; and any other dividing elements configured to enable exertion of pressure on the non-gaseous fluid in the second portion volume by the pressurised gas in the first portion volume.

7. The hydropneumatic suspension component according to claim 1, in which the first portion volume is provided in a cavity between an inner tube and an outer tube, and the first portion volume is isolated from the non-gaseous fluid in the second portion volume by an oleophobic filter or an open-cell foam.

8. The hydropneumatic suspension component according to claim 1, in which the first portion volume is provided in one or more conduits positioned on an outer surface of a tubular housing.

9. The hydropneumatic suspension component according to claim 8, wherein the outer surface comprises cooling fins on or adjacent the one or more conduits.

10. The hydropneumatic suspension component according to claim 8, wherein the conduit comprising the mass of an adsorptive material and/or open cell foam extends only partially along a length of the tubular housing, revealing the tubular housing to the outside air along the remainder of its length.

11. The hydropneumatic suspension component according to claim 8, in which the one or more conduits surround from 10 to 90% of a circumference of the tubular housing.

12. The hydropneumatic suspension component according to claim 11, in which the tubular housing is provided with one or more cooling fins on the circumference that is not surrounded by the one or more conduits.

13. The hydropneumatic suspension component according to claim 1, further comprising an auxiliary or “piggyback” chamber provided in fluid communication with the non-gaseous fluid in the second portion volume via a rigid or non-rigid connection, and housing the first portion volume.

14. The hydropneumatic suspension component according to claim 1, wherein the adsorptive material and/or open cell foam is attached to or contained within a moveable member, and the adsorptive material is in fluid communication with the first portion volume via a porous membrane or open-cell foam.

15. The hydropneumatic suspension component according to claim 1, wherein the adsorptive material is a bound unitary element of adsorptive material exposed to the first portion volume.

16. The hydropneumatic suspension component according to claim 1, wherein the adsorptive material and/or open cell foam are/is exposed to the first portion volume through one or more orifices.

17. The hydropneumatic suspension component according to claim 1, wherein the adsorptive material is an activated carbon featuring high levels of mesoporosity and low levels of microporosity.

18. The hydropneumatic suspension component according to claim 1, which is a gas charged damper.

19. A vehicle comprising a hydropneumatic suspension component according to claim 18.

20. (canceled)

21. (canceled)

22. (canceled)

23. A hydropneumatic suspension component comprising: a variable-volume chamber having a first portion volume for holding a pressurised gas and a separate second portion volume for holding a non-gaseous fluid used as a damping medium, wherein the first portion volume is provided in one or more conduits that partially surround an outer surface of a housing comprising the second portion volume.

24. The hydropneumatic suspension component according to claim 23, in which the housing comprising the second portion volume is tubular.

25. The hydropneumatic suspension component according to claim 24, in which the one or more conduits surround from 10 to 90% of a circumference of the tubular housing.

26. The hydropneumatic suspension component according to claim 25, in which the tubular housing is provided with one or more cooling fins on the circumference that is not surrounded by the one or more conduits.

27. The hydropneumatic suspension component according to claim 23, in which the first portion volume further comprises an adsorbent material and/or an open cell foam.

28. The hydropneumatic suspension component according to claim 27, in which the non-gaseous fluid in the second portion volume is isolated from the first portion volume by an oleophobic filter or an open-cell foam.

29. A floating piston for a hydropneumatic suspension component comprising: a main body comprising a chamber having an opening, and in which the chamber contains a mass of adsorptive material and/or open cell foam to limit the build-up of pressure in a hydropneumatic suspension component.

30. The floating piston according to claim 29, in which the main body is formed from a plastics material and/or a metal material.

31. The floating piston according to claim 29, in which the opening comprises a grill or a mesh, and in which the adsorptive material is provided in combination with an oleophobic filter, foam, or membrane.

32. The floating piston according to claim 29, in which the main body is further provided with sealing and/or scrapping elements that are arranged to communicate with a bore of the hydropneumatic suspension component in use.

33. The floating piston according to claim 32, further comprising a pressurised gas.

34. A hydropneumatic suspension component comprising a floating piston according to claim 29.

35. (canceled)

36. (canceled)

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0099] FIG. 1 Illustrates a gas-charged monotube damper in compressed and extended states.

[0100] FIG. 2 illustrates a gas charged monotube damper with the floating piston replaced by a flexible membrane

[0101] FIG. 3 illustrates a monotube gas-charged damper with an auxiliary or piggyback chamber.

[0102] FIG. 4 illustrates a standard twin tube gas-charged damper in compressed and extended states.

[0103] FIG. 5 illustrates a proposal for a novel twin tube gas-charged damper which preserves some of the benefits of a monotube configuration.

[0104] FIG. 6 illustrates an alternative gas-charged monotube configuration with the adsorptive mass housed within a floating piston.

[0105] FIG. 7 illustrates the change in pressure in a cavity under compression partially occupied by activated carbon, compared to an empty cavity.

[0106] FIG. 8 illustrates the effect of temperature on pressure in a sealed pressurised cavity using two types of activated carbon.

[0107] FIG. 9 compares the hysteresis in damping forces in a gas charged damper, with-and-without an adsorptive material disposed within the pressurised gas cavity

DESCRIPTION OF THE DRAWINGS IN DETAIL

[0108] FIG. 1 Illustrates an example of a hydropneumatic suspension component being a gas-charged monotube damper in compressed and extended states. The device is formed of a cylinder (101) that comprises a variable-volume chamber having a first portion volume (107) for holding a pressurised gas and a separate second portion volume (106) for holding a non-gaseous fluid used as a damping medium. An example of a non-gaseous fluid, preferably non-gaseous damping fluid, is an oil such as hydraulic oil.

[0109] The cylinder (101) comprises a piston (102) containing damping orifices (103) that is actuated via a piston rod (104) which enters one end of the cylinder (101) comprising the second proportion volume (106) through a sealed opening (105). The second portion volume (106) is entirely filled with non-gaseous fluid (such as oil), and in use the pressurised gas in the first portion volume (107) exerts pressure on the non-gaseous damping fluid via a floating piston (108).

[0110] A mass of adsorptive material (109) is disposed within the first portion volume (107) (i.e. the pressurised gas chamber). This limits the build-up of pressure in the damper as the first portion volume (107) is compressed in use by the non-gaseous fluid provided in the second portion volume (106). Additionally, and/or alternatively to the adsorptive material (109), a mass of open-cell foam can be disposed within first portion volume (107).

[0111] As shown, the non-gaseous fluid in the second portion volume (106) is isolated from the adsorbent material (109) (and/or open-cell foam) in the first portion volume (107) by the floating piston (108). This means the non-gaseous fluid in the second portion volume (108) is prevented from mixing and/or contacting the first portion volume (107).

[0112] In one embodiment, the first portion volume (107) is fluidly sealed from the second portion volume (106) by the floating piston (108). This means that the adsorbent material (109) (and/or open-cell foam) and the pressured gas in the first portion volume (107) are prevented from mixing and/or contacting the non-gaseous fluid in the second portion volume (106).

[0113] It will be appreciated that such isolation and/or sealing may also be achieved by a flexible divider, such as a flexible impervious membrane or any other dividing means to enable the exertion of pressure on the non-gaseous fluid in the second portion volume by the pressurised gas in the first portion volume.

[0114] For the avoidance of doubt, the volume of the first portion volume (107) increases in direct proportion to the amount of piston rod (104) that exits the second portion volume (106) upon extension of the device. The volume of the first portion volume (107) decreases in direct proportion to the amount of piston rod (104) that enters the second portion volume (106) upon compression of the device.

[0115] FIG. 2 illustrates a gas charged monotube damper with a similar working configuration to FIG. 1, but with the floating piston (102) replaced with a flexible membrane (201). This provides an alternative means of isolating the adsorbent material (and/or open-cell foam) in the first portion volume from the non-gaseous fluid in the second portion volume. Again, the effect is that the non-gaseous fluid in the second portion volume is prevented from mixing and/or contacting the first portion volume. The flexible member could further act to fluidly seal the first portion volume from the second portion volume. This would mean that the adsorbent material (and/or open-cell foam), and the pressured gas in the first portion volume are prevented from mixing and/or contacting the non-gaseous fluid in the second portion volume.

[0116] FIG. 3 illustrates a monotube gas-charged damper with an auxiliary or piggyback chamber in compressed and extended states. The chamber comprises a variable-volume chamber having a first portion volume (303) for holding a pressurised gas and a separate second portion volume (304) for holding a non-gaseous fluid used as a damping medium. The piggyback chamber further comprises a mass of adsorptive material disposed within the first portion volume (303). Additionally, and/or alternatively to the adsorptive material, a mass of open-cell foam can be disposed within first portion volume (303).

[0117] As shown, the second portion volume (304) extends to a main chamber of the damping device and is provided to be in fluid communication with a non-gaseous fluid provided in a main chamber of the damping device. This fluid connection from the piggyback chamber to the main chamber may be via a rigid or non-rigid connection. Such a connection may comprise a valve (306) between the main chamber and the piggyback chamber to control the flow of non-gaseous fluid, and therefore may afford fine damping control. Additionally, or alternatively, such a valve (306) may be provided to the main chamber itself (as shown) and/or to the piggyback chamber.

[0118] As shown, a floating piston (302) now sits within the auxiliary chamber (301). This means that the second portion volume (304) is isolated from the adsorbent material (and/or open cell foam) in the first portion volume (303). As such, the non-gaseous fluid in the second portion volume (304) is prevented from mixing and/or contacting the first portion volume (303).

[0119] In one embodiment, the first portion volume (303) is fluidly sealed from the second portion volume (304) by the floating piston (302). This means that the adsorbent material (and/or open cell foam) and the pressured gas in the first portion volume (303) are prevented from mixing and/or contacting the non-gaseous fluid in the second portion volume (304).

[0120] Providing the piggyback chamber with a mass of adsorptive material disposed within the first portion volume (303) limits the build-up of pressure in the damper device as the first portion volume (303) is compressed in use by the non-gaseous fluid provided in the second portion volume (304).

[0121] FIG. 4 illustrates a standard twin tube gas-charged damper in a compressed state. The device comprises an inner tube (401) that is housed within an outer tube (402). A piston and piston rod are provided to the inner tube (401) as shown.

[0122] The damper comprises a variable-volume chamber that comprises a first portion volume for holding a pressurised gas and a separate second portion volume, for holding a non-gaseous fluid used as a damping medium. The second portion volume is provided within the inner tube (401) and extends from a sealed end of the inner tube (401) to an open end of the inner tube (401). The second portion volume further extends from an open end of the inner tube (401) to a void or cavity provided between the inner tube (401) and the outer tube (402). As shown the second portion volume in the cavity (404) may extend to around a mid-point of the cavity or may extend to around 25 to 75% of the length of the cavity.

[0123] The device further comprises a valve (403) to manage the flow of non-gaseous fluid in the second portion volume. In particular, as shown, it may be position at the open end of the inner tube (401) to control the flow of non-gaseous fluid from within the inner tube, to the cavity.

[0124] A first portion volume for holding a pressurised gas is provided within the remaining section of the cavity that is not occupied by the second portion volume.

[0125] In one embodiment as shown, the first portion volume contains a mass of adsorptive material (405) to limit the build-up of pressure as the first portion volume is compressed in use by the non-gaseous fluid provided in the second portion volume. The non-gaseous fluid in the second portion volume is also kept under pressure by the pressured gas provided in the first portion volume.

[0126] The adsorbent material (405) in the first portion-volume (which takes either monolith or granular form) and the pressurised gas, is isolated from non-gaseous fluid by a band of oleophobic foam or filter material (406) which circumvents the cavity and provides a means to separate the first portion volume from the second portion volume. The effect is that the non-gaseous fluid in the second portion volume is prevented from mixing and/or contacting the first portion volume.

[0127] In one embodiment, the first portion volume may additionally or alternatively to the adsorbent material (405), comprise a mass of open-cell foam. The mass of open-cell foam may substantially fill the first portion volume of the device. Due to the mass of open-cell foam in the first portion volume, this means the non-gaseous fluid in the second portion volume is prevented from mixing and/or contacting the first portion volume.

[0128] FIG. 5 illustrates a proposal for a novel twin tube gas-charged damper which preserves some of the benefits of a monotube configuration.

[0129] The damper comprises a variable-volume chamber that comprises a first portion volume (503) for holding a pressurised gas and a separate second portion volume (501), for holding a non-gaseous fluid used as a damping medium. The non-gaseous fluid surrounds a piston rod (502) and piston similar to the embodiment shown in FIG. 4.

[0130] As shown from FIG. 5, the first-portion volume (503) is provided in one or more conduits (504) that partially surround an outer surface of a housing comprising the second portion volume (501). It is preferable that the housing is tubular, or as a tube with a circular cross section, as shown. The first-portion volume (503) may be provided in two or more conduits (504) as shown. The one or more conduits surround from 10 to 90%, preferably from 10 to 75%, further preferably from 20 to 60% of a circumference of the tubular housing. The housing may comprise one or more cooling fins and/or structural buttresses (505) on its outer surface that is not surrounded by the one or more conduits (as shown), to aid cooling of the second portion volume (501).

[0131] The first-portion volume (503) comprises a mass of adsorptive material to limit the build-up of pressure as the first portion volume (502) is compressed in use by the non-gaseous fluid provided in the second portion volume in a manner similar to the embodiment of FIG. 4. The first portion volume (503) may additionally or alternatively to the adsorptive material (405), comprises a mass of open-cell foam.

[0132] Ideally, the conduit (504) is limited to consist of the first portion volume (503), but it may comprise both the first-portion volume (503) and a portion of the second-portion volume (501) as per the embodiment of FIG. 4. In a preferred arrangement, and as shown, the pressurised gas and adsorbent material in the first portion-volume (503) is isolated from the non-gaseous fluid in the second portion volume (502) by oleophobic filters or open cell foam at the base (506) of the conduit (504). It could be envisaged that such filters or open cell foams could alternatively be provided to any section of the conduit (504) to isolate the second portion volume (501) from the first portion volume (501). The effect is that the non-gaseous fluid in the second portion volume is prevented from mixing and/or contacting the first portion volume.

[0133] As discussed above, the first portion volume may additionally or alternatively to the adsorbent material, comprise a mass of open-cell foam. The mass of open-cell foam may substantially fill the first portion volume of the device. Due to the mass of open-cell foam in the first portion volume, this means the non-gaseous fluid in the second portion volume is prevented from mixing and/or contacting the first portion volume.

[0134] FIG. 6 illustrates an alternative gas-charged monotube configuration with a mass of adsorptive material housed contained within a hollowed out, extended floating piston (601).

[0135] As shown, the floating piston (601) comprises a main body (602) comprising a chamber having an opening (604), and in which the chamber contains a mass of adsorptive material and/or open-cell foam to limit the build-up of pressure in a hydropneumatic suspension component. The main body (602) is constructed from a plastics material and/or a metal material.

[0136] Protection to the adsorptive material is enhanced by the use of an oleophobic filter, foam or membrane behind a grill or broad mesh (605) on the opening (604), to keep fine particles of dust from entering the hydropneumatic suspension component, where it may mix with the film of oil lubricating the walls and increase friction with the isolating seals.

[0137] The main body may be further provided with sealing and/or scrapping means (603) that are arranged to communicate with a bore of the hydropneumatic suspension component in use. Such means (603) or anti-drip details will help protect the adsorptive material from splashes of non-gaseous fluid (i.e. oil or damping fluid) in use. A projection such as a lip or a groove with an o-ring/piston ring would also achieve the same effect.

[0138] FIG. 7 illustrates the relative change in pressure as a chamber is compressed, with and without activated carbon being present. The experiment is described in detail in the Description.

[0139] FIG. 8 illustrates the effect of temperature on relative pressure on a pressurised air-filled cavity containing a highly microporous activated carbon compared to one with fewer micropores and more mesopores. The experiment is described in more detail in the Description.

[0140] FIG. 9 illustrates damping force hysteresis in a gas charged damper. The solid line shows the damping force of a regular gas charged damper in compression and extension. The dotted line shows the damping force in the same device when activated carbon occupies the whole of the gas charged cavity at peak compression and at maximum operating temperature. The experiment shows substantially reduced hysteresis in the damper with adsorptive material disposed within the gas charged cavity.