Land vehicles – Wheeled – Running gear
Patent
1997-10-24
2000-08-15
English, Peter C.
Land vehicles
Wheeled
Running gear
280124159, 267 6415, 267 6425, 267186, B60G 1126, B60G 21073
Patent
active
06102418&
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a hydropneumatic suspension system, particularly for the wheel support in motor vehicles, with at least one suspension arrangement consisting essentially of at least one hydraulic spring strut, at least one hydropneumatic spring reservoir and at least one damping valve, wherein the spring strut consists of a cylinder containing a hydraulic medium and a piston, movably guided therein, for the spring compression and rebound and the piston separates a cylinder space from an annular space surrounding a piston rod and wherein the cylinder space is connected via the damping valve with the spring reservoir bringing about a spring tension.
BACKGROUND OF THE INVENTION
Such a suspension system is described, for example, in European Patent No. 0,515,991 B1. This known system has already proved rather successful, i.e., particularly because it operates in accordance with the new principle of a "stutter-damping arrangement" (for this purpose, also compare German Patent No. 4,117,455 C2), wherein during the rebound of the spring strut, inside the damping valve, a flow path for the hydraulic medium is blocked and reopened in a constantly alternating manner. Hereby, the rapid advance of the spring strut in the rebound, which is detrimental to most applications, is effectively prevented wherein during the rebound a controlled, measured, successive "abatement" of the hydraulic medium passing from the spring reservoir into the spring strut takes place until the rebound movement is entirely completed. In this way, a detrimental, too rapid spring-back movement or recoiling of the wheel onto the road is prevented. In addition, according to EP 0 515 991 B1 (FIGS. 1 and 7), it is provided for this purpose that also the annular space of each spring strut is connected, possibly via an additional damping valve (FIG. 11), with an additional pressure reservoir, so that against the spring resistance, produced by the spring reservoir inside the cylinder space, a certain counterforce is always exerted on the side of the annular chamber. In an alternative embodiment (FIG. 12), the cylinder space and the annular space are connected with the same spring reservoir via one of two damping valves, respectively. All of these measures lead to a rather costly arrangement of structural components (reservoir, damping valves).
SUMMARY OF THE INVENTION
It is the task of the present invention to further improve the known system so that, while costs are reduced in such a way that for system components at least continuously good, particularly improved application properties, primarily with respect to the stabilization of the vehicle for the purpose of guarding against lateral wavering about the longitudinal axis of the vehicle (for example, on curves) and/or against tilting or "pitching" about the transverse axis of the vehicle (for example, during braking) can be achieved.
In accordance with the invention, this is achieved in that the annular space of the spring strut is directly connected with one of the spring reservoirs while the damping valve is circumvented.
By means of this solution of the invention, with a minimum number possible of system components (per spring strut, only one spring reservoir and only one damping valve are required), a very effective stabilization can be achieved. In the dynamic state, particularly during the rebound of the spring strut, due to the differential annular area in the spring strut, a pressure difference occurs between the cylinder space and the annular space. This is due to the fact that the hydraulic medium flowing into the cylinder space flows across the damping valve representing a "flow resistance," while simultaneously hydraulic medium flows from the annular space, in a manner involving virtually no flow loss, into the spring reservoir, since in the connection from the annular space to the spring reservoir--except for slight flow losses in the lines--no pressure-influencing elements are present. This causes the reservoir pressure to exist virtually
REFERENCES:
patent: 3101220 (1963-08-01), Wettstein
patent: 3356954 (1967-12-01), Gottschalk
patent: 3672628 (1972-06-01), Aanstad
patent: 4014510 (1977-03-01), Smith
patent: 5344124 (1994-09-01), Runkel
Patent Abstracts of Japan, vol. 015 No. 060 (C-0805), Feb. 13, 1991, JP,A,02 289419, Nov. 29, 1990.
English Peter C.
Hemscheidt Fahrwerktechnik GmbH & Co.
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