Patent Application
20110233014
The present invention relates to a suspension apparatus.
Force dampening systems or suspension units are used in many fields of engineering and construction for damping force induced motion. Examples of such use include use in vehicles to couple wheels to a vehicle chassis and in prime movers for attaching seats to a floor. Known suspension units often comprise mechanical (steel) springs and/or hydraulic shock absorbers.
The suspension unit described herein may be used in any field of engineering, construction and transport in which prior art suspension units are currently used.
It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or any other country.
In the claims and description of the invention, except where the context requires otherwise due to express language or necessary implication, the words “comprise” or variations such as “comprises” or “comprising” are used in an inclusive sense, i.e., to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.
In a first aspect of the present invention there is provided a suspension apparatus for providing a progressively dampened motion, said apparatus comprising:
a housing defining a first chamber and having a first end, said first chamber containing a volume of liquid;
a plunger defining a second chamber, said plunger movable within said housing and containing a volume of gas; and,
a fluid communication path between the first and second chambers, wherein movement of said plunger within said housing causes transfer of liquid between said first and second chambers;
wherein said gas is compressed by flow of said liquid into said second chamber;
wherein said fluid communication path becomes progressively constricted as said plunger is moved toward said first end of said first chamber.
In an embodiment of the present invention the fluid communication path comprises at least one aperture through which the liquid passes when flowing from the first chamber to the second chamber and the at least one aperture becomes progressively obstructed as the plunger moves toward the first end. A further embodiment can be realised wherein the plunger slides along at least one guide disposed within said housing. In an embodiment the guide extends from the first end. Furthermore, the guide may define a third chamber that is in fluid communication with the second chamber and wherein the at least one aperture is formed within the guide providing fluid communication between the first and second chambers. A further embodiment may comprise a plurality of apertures that are progressively obstructed as the plunger moves toward the first end of the first chamber.
An alternative form of the current embodiment may comprise the at least one aperture comprising a gap between the plunger and the guide. The gap may comprise a space formed between an opening in the plunger and an outer surface portion of the guide received in the opening. The outer surface portion of the guide may also have a varied cross sectional perimeter along the length of the guide. The varied cross sectional perimeter of the guide may increase along the length of the guide toward an end proximal the first end. It may also be appreciated that the cross sectional perimeter of the opening within the plunger, through which said guide is received, is varied along the length of the opening. In the previous embodiments described the guide may comprise a stem concentric with a central axis of the first chamber. Furthermore, the plunger may also be concentric with the central axis of the first chamber.
In a second aspect of the present invention there is provided a suspension apparatus for providing a progressively dampened motion, said apparatus comprising:
a housing defining a first chamber having a first end, said first chamber containing a volume of liquid;
at least one plunger defining a second chamber containing a volume of gas, said plunger movable within said housing; and,
a stem defining a third chamber which is in fluid communication with said second chamber, said stem having at least one aperture permitting fluid communication between said first and third chambers whereby liquid is transferred between said first chamber and second chamber via said third chamber so as to compress said gas and said at least one aperture becomes progressively obstructed when said plunger is moved toward said first end of the first chamber.
In accordance with the second aspect of the present invention the stem is formed with a cross section that is generally uniform. The stem extends from the first end of the housing. It may further be recognized that a distal end of the plunger may also be of a uniform cross section. Furthermore, a plunging portion of the plunger may be of a dimension that is greater than the distal end of the plunger. In a further embodiment the stem and the plunger are concentric with a central axis of the first chamber.
In an embodiment the stem comprise a plurality of apertures and wherein each of the apertures is located within a single cross sectional plane through the stem. In one form of the at least one aperture comprises a slot having a portion that extends along the length of said stem.
In a third aspect of the present invention there is provided a suspension apparatus for providing a progressively dampened motion, said apparatus comprising;
a housing defining a first chamber having a first end, said first chamber containing a volume of liquid;
at least one plunger defining a second chamber containing a volume of gas, said plunger movable within said housing; and,
a stem configured in such a manner so as to define in combination with said plunger a progressive constriction of a fluid flow path through which liquid flows from said first chamber into said second chamber so as to compress said gas when said plunger is moved towards said first end of the first chamber.
In accordance with the third aspect of the present invention the stem extends from said first end and is tapered in a direction toward a distal end of the stem. Further, an inwardly facing surface of said plunger opposite said taper of said stem may be configured so that said progressive constriction is greatest when said plunger is nearer the first end of the first chamber. In an embodiment the stem defines a third chamber in fluid communication with said second chamber providing fluid communication through at least one aperture that may be axially or radially spaced within said stem, to permit transfer of liquid from the first chamber to the second chamber.
The at least one aperture may comprise a plurality of apertures of the same dimension or a plurality of apertures of different dimensions. Furthermore, at least one of said aperture(s) may be configured to offer a variable dimension to regulate liquid or fluid transfer accordingly. It may be further realised that the variability could be either automatic or manual effected by a control system or manual adjustment means. The variability of the aperture dimension may be influenced by the required dampening rate or regulated by a specific passive or active control system monitoring the applied loads and liquid transfer rate while the plunger is operable.
Applicable to each of the aspects of the present invention described above is a base of said housing that is rigidly mounted to a load bearing structure. Further, the load bearing structure may comprise a chassis or floor of a marine craft. Furthermore, a body, that is to be isolated from any external or any transmitted forces, may be rigidly mounted to the plunger. It may be readily appreciated that such a body may comprise a chair, seat or similar item.
Applicable to each of the aspects of the present invention described above is the use of at least one sealing means that is provided within at least one aperture of said housing into which said plunger is slidingly engaged.
Applicable also to each of the aspects of the present invention described above is where the plunger may be configured with an air valve into which a compressor or like means may be connected into so as to increase the pressure of said volume of gas.
Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which;
A first embodiment of the present invention is shown in
Within the housing (14) there is provided at least one plunger (6) which additionally defines a second chamber (8). The plunger (6) is configured in such a manner so as to be telescopically movable within the housing (14) while containing a volume of gas (56) within a distal end (4). In order to achieve a low co-efficient of friction, while maintaining an adequate hydraulic seal between the plunger (6) and the housing (14), seal rings (42) are located within the inwardly facing surface of an aperture (45) within in a neck portion (46) of housing (14). Use of the sealing rings (42) allows the plunger (6) adequate movement to affect the required stroke or displacement when in operation. It will be appreciated that other means may be included to provide an adequate sealing yet reduced friction effect.
For the current embodiment considered,
For the current embodiment shown in
The transfer of fluid can be described by considering
Liquid transfer may also be partly established by virtue of a first clearance (48) and a second clearance (50) denoting the respective dimension between the external surface of plunger (6) and the internal wall of the first chamber (12) (clearance (48)) and the surfaces of said plunger that are proximal to the guide or stem (18) when slidingly engaged (clearance (50)). Fluid passing through clearance (50) may contribute to the body of fluid entering the second chamber (8), however, fluid passing through clearance (48) will enter a portion of the first chamber (12) that is separated from the second chamber (8) by the walls of the plunger (6). Therefore, liquid passing through clearance (48) will affect to reduce the reactive load experienced by the plunger (6) and provide an alternate leak path for the liquid during a plunging operation (54). Clearances (48) and (50) are configured in the current embodiment to permit a limited amount of fluid flow to allow at least a lubricating effect to be established to reduce friction between the outer surfaces of plunger (6) with the walls of the first chamber (12) and those of the guide or stem (18). In respect of the presently described embodiment, clearances (48) and (50) would most likely be described by those skilled in the art as being of a “neat” or “snug” fit dimension.
The plunging motion of plunger (6), as shown in
Once the plunger (6) has ceased to move due to the “hydraulic lock” equilibrium point being reached, removal of the applied load (58) will permit the plunger (6) to begin to return to the first state shown in
A feature influencing the rate of fluid flow between the first chamber (26) and second chamber (8) is the dimension of the aperture holes (20) within the stem portion (18). It would be readily evident that the number and dimension of the aperture holes (20) will greatly influence the transfer of fluid in either forward (plunging (54)) or return (55) operations thus influencing the characteristic rate of the progressive damping motion of the plunger (6) in response to the external load (58). Depending upon the application into which the current embodiment of the present invention is employed, the stem portion (18) may be fabricated with any number of apertures with each aperture being either of the same dimension or of differing dimensions. In particular the number of apertures may vary along the length of the guide or stem (18). In some embodiments of the present invention such apertures (20) may comprise a slot or similar type opening that may be facilitate the flow or transfer of liquid between chambers. The slot could be aligned radially or axially along the length of the guide or stem (18). In such instances, progressive constriction of the flow would occur as the plunger (6) progressively obstructs the opening (thus reducing the fluid communication pathway) and limiting the transfer of liquid. The placement or location of the aperture(s) within the guide or stem (18) may also be axially along the length of the guide or stem (18) or spaced radially within a single cross sectional plane or comprise a combination of both placement types. The latter being partly or wholly dependant upon the flow rate or characteristics dampening rate required for the given application.
Another embodiment of the present invention may be realised in that a plurality of guide or stem (18) may exist within a housing (14) with a plurality of complementary plungers (6). Particular loading applications may require specific effective progressive dampening motions that may be facilitated by more than one guide or stem (14)/plunger (6) combination existing within a first chamber (12) of a housing (14). For such a configuration, the workings of the previously described embodiments would remain the same with there being a plurality of plunger/stems operating in unison, in parallel or in series. It will be readily appreciated that the load transmission and application to each distal end (4) of each plunger (6) will be by way of an appropriate mechanical load transmission means. Such may involve a plate or the like rigidly joining all distal ends (4) together to ensure all plungers work or operate in unison when subject to external loading. It may be further realized that the load transmission component may be adapted or configured in such a way so as to align different plungers (6) at different initial displacements so as to have different first states depending upon the characteristic of the dampened motion required for the particular application. Therefore, the rate of fluid flow, and thus the resulting dampened motion achieved, will be influenced by where each contributing plunger element is placed relative to the associated apertures (20) prior to a plunging motion beginning. Such an embodiment may have useful benefits when used to provide a damping means for high load applications where specific progressive dampening rates are required.
It may further be realised that a mechanism could be included within the previously described embodiments to provide a means of actively controlling the size of a single aperture hole or a plurality of aperture holes (20). Such a mechanism could then adjust or vary the size of the aperture(s) in accordance with the applied load or required dampening thus altering the fluid transfer rate and changing the characteristic damping rate. A system could be realized whereby the applied loads, liquid transfer rate and motion characteristics (velocity, acceleration and displacement) of the plunger (6) are monitored during the plunging operation allowing the computation of the associated dampening rate. The computed dampening rate could be compared to the required or desired dampening rate in order to determine whether or not the aperture dimension should be altered. Such a system could also be employed to selectively close some of the apertures to vary the dampening rate.
A further embodiment (98) of the present invention is shown in
Fluid transfer between the second chamber (8) and the first chamber (12) may be assisted by the presence of a top fluid port (10) of
In all embodiments of the present invention described herein, it will be appreciated by those skilled in the art that the position at which the “hydraulic lock” occurs is highly influenced by the relative pressure of the gas contained within plunger (6) having been compressed by the liquid. In some instances it may be preferable to provide a mechanism for increasing the relative pressure of the gas contained within the distal end (4) of the plunger (6). One practical method of achieving this is shown in
An example of the implementation of any one of the previously described embodiments, in accordance with the present invention, is shown in
It may be appreciated that numerous variations and modifications will suggest themselves to a person skilled in the relevant art, in addition to those already described, without departing from the basic inventive concepts. All such variations and modifications are to be considered within the scope of the present invention, the nature of which is to be determined from the foregoing description.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/AU2008/000062 | 1/17/2008 | WO | 00 | 6/21/2011 |
