Spring devices – Vehicle – Comprising compressible fluid
Reexamination Certificate
1998-09-28
2001-11-06
Oberleitner, Robert J. (Department: 3613)
Spring devices
Vehicle
Comprising compressible fluid
C188S322130, C188S322150, C188S313000
Reexamination Certificate
active
06311961
ABSTRACT:
FIELD OF THE INVENTION
The present invention refers to a hydro-pneumatic suspension unit, in particular to a device providing both spring and shock-absorber functions. The present invention is useful for enabling a machine part subjected to shocks, bumps, jerks or displacements to substantially maintain or recover its original, or balanced, position, providing a swift and smooth response to external mechanical disturbances.
The shock-absorber function, within the context of the present invention, is related to dampening movement transmitted from a movable part to another part supported thereon or otherwise connected thereto. Likewise, the function of the spring is to maintain support of the movable part at a predetermined height or distance from the other part, by resiliently urging the movable part back to its original placement once the external force causing movement thereof has ceased.
Although the ensuing description generally refers to applications involving land vehicles, more particularly automobiles, the present invention may be used in or adapted to other applications, encompassing other forms of locomotion, such as bicycles or motorcycles for instance, and support means for vibrating, revolving and/or reciprocating industrial or domestic machine parts. In the automobile application, the unit of the invention has been designed to replace all springs and/or torsion bars and shock absorbers in axle suspension units.
BACKGROUND OF THE INVENTION
U.S. Pat. No. 3,762,514 to Freitag (issued October, 1973) discloses an adjustable-length support column designed for a vehicle seat to reduce resiliency under overload condicitons, such as in the event of a vehicle collision. The column includes a piston for attachment to a movable part and a floating piston mounted in separate parts of a cavity divided by a fixed wall. The wall has a normally-open throttle valve designed to close when the hydraulic pressure in the first piston cavity part suddenly increases, thereby substantially reducing column resiliency under collision conditions. The floating piston rests on an pneumatic cushion and the first piston includes a longitudinal through bore which respectively provide resiliency and shock-absorbing effects.
However, the Freitag unit may not be mounted alone for a vehicle suspension unit, that is it would require a spring, for example, to maintain the proper height of the part requiring support. Otherwise, unrestricted flow of the hydraulic fluid through the first piston bore would lead to the piston dropping down and coming to rest on the fixed wall.
U.S. Pat. No. 3,817,566 to Keijzer et al (issued June, 1974) discloses an energy absorber wherein a three-position valve assembly is deformed by fluid pressure developed when an external force acts on a piston. A resulting substantial valve deformation enables gas to pass therethrough thereby pressurizing a housing. Once impact is over, the gas bleeds back through the now less-deformed valve to restore the bumper to its original position. The Keijzer device is suited for vehicle bumpers and the like for absorbing energy generated by collisions under about 16 km/h (10 mph).
U.S. Pat. No. 4,506,869 to Masclet et al (issued March, 1985) discloses an aircraft hydro-pneumatic shock absorber having a hydraulic chamber containing a piston and a fixed partition wall. The piston is provided with a fairly large orifice freely communicating oil from said chamber to a second chamber integral with the piston and containing partly oil and partly air, the latter providing a known predetermined spring function. The wall has a constriction valve and across the wall from the piston there is provided a floating piston separating the oil from a pneumatic chamber, thereby providing a second spring function. The latter function may be varied by means of a computer-controlled movable head in the pneumatic chamber, which has the effect of lengthening and shortening the shock absorber, thereby providing an electronically variable force-plunging function for specifically adapting to different aircraft load conditions and take-off and landing absorber roles.
The Masclet unit would require constantly monitoring for hydraulic fluid leakages, since an eventual loss of oil would also render the pneumatic part unoperative
Other known references in the field comprise the following U.S. Patents:
U.S. Pat. No. 2,410,176 (Magnum)
U.S. Pat. No. 3,801,087 (Akaike et al)
U.S. Pat. No. 3,865,356 (Wüssner)
U.S. Pat. No. 4,423,801 (Miura)
U.S. Pat. No. 4,687,187 (Bellapadrona)
U.S. Pat. No. 4,795,009 (Tanahashi et al)
U.S. Pat. No. 4,821,983 (Aubry et al)
U.S. Pat. No. 5,330,132 (Lucienne et al)
The disclosures of the above-mentioned U.S. patents are hereby incorporated herein by reference.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide a suspension unit for supporting a first part on a second part, said parts being movable relative to one another, without the need of additional springs, torsion bars or shock absorber units.
Another object is a suspension unit which is relatively simple to adjust to desired operating conditions from the outside, without having to dismount nor disassemble the unit.
A further object is a suspension unit for mounting in land vehicles for providing smoother travelling conditions, increased tracking (i.e. road surface contact) through curves, better stability during sudden acceleration and braking, greater engine efficiency, increased vehicle load capacity and factory adaptability to a wide range of vehicle kinds, particularly insofar the desired mounting height or distance between the two vehicle parts (e.g. axle and chassis) to be connected by the unit.
These and other objects and advantages, which may become apparent in the course of the ensuing description, are achieved by means of a dual-chamber suspension unit according to the present invention. The unit comprises: stationary housings respectively defining a first chamber and a second chamber therein; a first piston slidably mounted in the first chamber and defining therein a first space adjacent the piston for an uncompressible fluid and a second piston slidably mounted in the second chamber and defining therein a second space for the uncompressible fluid adjacent the second piston; restricted passage means for communicating fluid back and forth between the first and second spaces in response to sliding movement of the first piston in the first chamber, whereby movement externally applied to the first piston causes the uncompressible fluid to flow from one space to the other the space through the passage means and further causing displacement of the second piston in the second chamber; and resilient means, most preferably comprising a third space for a compressible fluid in the second chamber across the second piston from the second space, for biasing the second piston means in an intermediate placement in the second chamber generally corresponding to a normal placement of the first piston in the first chamber. Following such a displacement, the compressed fluid in the third space urges the second piston back to its placement which, in turn, urges the first piston back to its normal placement in the first chamber, thereby realizing a spring function for maintaining a predetermined distance between the movable parts, whereas the restricted passage means dampens the movement of the pistons, the unit of the invention thereby providing combined spring and shock-absorber functions.
In a first embodiment, the first and second housings are affixed to each another forming a common structure such that the first and second chambers are coaxially aligned. Preferably, a longitudinally-stiff rod mechanically connects both pistons so that they displace in tandem together. The rod may continue its extension through the first piston to an end adapted for anchorage of the suspension unit.
In a second embodiment, the second piston is a floating piston, such that displacement thereof is caused by fluid pressure increasing in the second space in response to an inflow of u
AuBuchon F. David
Brinks Hofer Gilson & Lione
Oberleitner Robert J.
Torres Melanie
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