Land vehicles – Wheeled – Running gear
Reexamination Certificate
2000-03-16
2001-12-25
Swann, J. J. (Department: 3611)
Land vehicles
Wheeled
Running gear
C280S005515, C267S064210
Reexamination Certificate
active
06332624
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to an air-suspension system having at least one air spring for installation between a chassis and a vehicle component mounted for oscillating along an oscillatory path relative to the chassis, the air spring having a control valve for feeding, blocking, or discharging compressed air in the air spring.
2. Description of the Related Art
An air suspension system is disclosed, for example, in German reference DE 33 47 435 A1 having an air spring connectable between a chassis of a vehicle and a vehicle component mounted for oscillating along an oscillation path relative to the chassis. A control valve is arranged for feeding, blocking, or discharging compressed air in the air spring. A basic problem with the disclosed system is that it is difficult to fit and adjust the control valve or a actuating device for the control valve so that a certain switching position of the control valve is set as a function of a loading state or a stroke position of the air spring.
Additional construction space and fitting material (i.e., holders, linkages, screws, etc.) are required for fitting the external level control valve.
During the fitting of the control valve, the vehicle component mounted for oscillating is put into a defined position relative to the chassis and an adjustment of the actuating device is made in this position. However, this sequence of work is difficult to integrate in an assembly line production.
Furthermore, the operability of the external level control valve and thus of the vehicle may be impaired by dirt or moisture when using an air-sprung vehicle in difficult terrain.
Another air-suspension system for a motor vehicle is disclosed in German reference DE 34 27 902 A1 having at least one air spring between a chassis and a vehicle component mounted for oscillating along an oscillatory path relative to the chassis. This reference also has a control valve for feeding and discharging compressed air inside the air spring, wherein the control valve is activated via an actuating device which is likewise arranged inside the air spring.
Yet another air-suspension system for a motor vehicle is disclosed in German reference DE 44 09 252 C2 with at least one air spring arranged between a chassis and a vehicle component mounted for oscillating movement along an oscillatory path relative to the chassis and a control valve arranged inside the air spring. The control valve has control positions for feeding, blocking and discharging compressed air and is activated via a control element which is likewise arranged inside the air spring. A guideway of the control valve acts on one of the two air-spring subassemblies of the outer tube and the rolling tube which are movable relative to one another. This control valve is designed as a rotary-slide valve activated via the guideway and a rotary-slide valve body. In the embodiment according to
FIGS. 6 and 7
of this reference, the control element is firmly connected to the outer tube. The result of this control element arrangement is that the entire length of the control element has to be accommodated inside the air spring. Consequently, the rolling tube must be arranged relatively close to the base of the vibration damper which restricts the heat exchange between the vibration damper and the surroundings.
SUMMARY OF THE INVENTION
The object of the present invention is to develop an air-suspension system in such a way that the fitting and adjustment work for a control valve is simplified, the operability of the air-suspension system is ensured even under adverse circumstances and the construction cost and amount of construction space of the system are at least reduced with respect to the prior art.
The object is achieved according to the present invention by an air-suspension system for use in a motor vehicle having a chassis and a vehicle component operatively mounted for moving along an oscillatory path relative to the chassis, wherein the air suspension system comprises an air spring connectable between the chassis and the vehicle component. The air spring has an outer tube air-spring subassembly and a rolling tube air-spring subassembly movable relative to the outer tube air-spring subassembly along a stroke length. A control valve is arranged inside the air-spring and has a compressed-air feed connection and a discharge connection. The control valve is selectively actuatable to a discharge position for discharging compressed air from the air spring via the discharge connection, a feed position for feeding compressed air to the air spring via the compressed-air feed connection, and a block position for blocking the flow of compressed air to and from the air spring. The inventive air-suspension system further comprises a control element operatively arranged in the air spring for actuating the control valve in response to a relative position of the rolling tube air-spring subassembly and the outer tube air-spring tube assembly. The control element has an effective length that is shorter than the stroke length of the air spring. Furthermore, the control element is in a releasable operative connection with one of the rolling tube air-spring subassembly and the outer tube air-spring subassembly, the releasable operative connection being limited to a portion of the stroke length of said air spring.
The control element has a guideway that is shorter than the stroke length of the air spring. The one of the rolling tube air-spring subassembly and the outer tube air-spring subassembly in releasable operative connection with the control element actuates the control element, wherein the releasable operative connection being restricted only to a section of the stroke travel between the outer tube air-spring subassembly and the rolling tube air-spring subassembly.
The great advantage of the inventive design lies in the fact that the position of the rolling tube may be shifted toward the top end of the vibration damper due to the restricted axial overall length of the rolling tube. Accordingly, the vibration damper has a larger contact area with the surrounding air facilitating heat dissipation. Furthermore, the mass of the control element is reduced because of the shortened overall length relative to the prior art.
The releasable connection between the one of the outer tube air-spring subassembly and the rolling tube air-spring subassembly is formed by contact surfaces in each case on the control element and the one of the outer tube air-spring subassembly and the rolling tube air spring subassembly.
In a further embodiment, the control element is arranged in an axially floating manner inside the rolling tube. If the rotary-slide valve and the control element are arranged in the rolling tube, the setting operation required by the prior art may be eliminated.
Thus the spring element may be arranged between the control element and a supporting surface of the rolling tube. One end position of the control element is supported axially on the rotary-slide valve. Accordingly, the control element is prevented from vibrating uncontrollably in the axial direction during a spring deflection action. The end position may also be implemented via a stop independently of the rotary-slide valve, but the components would then be more complicated. The axial support via the rotary-slide valve allows a simple axial fitting to be maintained.
Furthermore, the control element has an anti-rotation locking means in the circumferential direction. The purpose of the anti-rotation locking means is to prevent an uncontrolled rotary movement of the control element from occurring, which could impair the control action.
In addition to being designed as a simple control rod, the control element may optionally be designed as a cylinder. A cylindrical control element has the advantage that relatively high strength is obtained solely on account of the geometrical form.
In this case, the control element has a pocket-shaped recess in which the guideway is arranged. Alternatively, the guideway may also be made in one piec
Gilsdorf Joachim
Herold Winfried
Cohen & Pontani, Lieberman & Pavane
Dunn David R.
Mannesmann Sachs AG
Swann J. J.
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