Spring devices – Vehicle – Comprising compressible fluid
Reexamination Certificate
2002-03-25
2004-04-27
Siconolfi, Robert A. (Department: 3683)
Spring devices
Vehicle
Comprising compressible fluid
C267S064280, C280S124160
Reexamination Certificate
active
06726189
ABSTRACT:
BACKGROUND OF THE INVENTION
A closed level control system for a vehicle is disclosed in U.S. Pat. No.
6,685,174, and incorporated herein by reference. The level control system known from this application includes an air dryer via which air can be drawn from the atmosphere by suction with the aid of the compressor and can be transferred into the pressurized medium supply vessel for leakage compensation. Pressurized air can be discharged from the pressurized medium supply vessel into the atmosphere via the air dryer to regenerate the latter. With the integration of the air dryer into the level control system, it is substantially ensured that dehumidified air is in the level control system so that the components of the level control system are protected from corrosion and icing. It has, however, been determined that in a level control system known from the above publication, the air dryer directly faces the atmosphere so that the air dryer continuously takes up atmospheric moisture from the atmosphere. Under some circumstances, this can lead to the situation that the air dryer does not fulfill its function or cannot fulfill its function adequately. This problem could be solved in that the air dryer is correspondingly dimensioned but this would lead to a complicated configuration and high costs of the air dryer.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a closed level control system which includes an air dryer which is always available for air drying and furthermore has a simple configuration.
The closed level control system of the invention is for a vehicle having a vehicle body, vehicle axles and pressurized medium chambers with which the vehicle body is suspended relative to corresponding ones of the vehicle axles. The closed level control system includes: a pressurized medium supply vessel for holding a medium under pressure as a pressurized medium; a compressor for transferring the pressurized medium between the supply vessel and the pressurized medium chambers; the compressor having an input and an output; a first controllable directional valve switchable between a base position wherein no throughflow is permitted and a switched position wherein throughflow is permitted; a first pressurized air line connecting the supply vessel to the input of the compressor via the first controllable directional valve; a second controllable directional valve switchable between a base position wherein no throughflow is permitted and a switched position wherein throughflow is permitted; a second pressurized air line connecting the output of the compressor to the pressurized medium chambers via the second controllable directional valve; the pressurized medium being transmitted from the supply vessel to the pressurized medium chambers by the compressor when the first and second controllable directional valves are in the switched position; a third controllable directional valve switchable between a base position wherein no throughflow is permitted and a switched position wherein throughflow is permitted; a third pressurized air line connecting the input of the compressor to the pressurized medium chambers via the third controllable directional valve; a fourth controllable directional valve switchable between a base position wherein no throughflow is permitted and a switched position wherein throughflow is permitted; a fourth pressurized air line connecting the output of the compressor to the pressurized medium supply vessel via the fourth controllable directional valve; the pressurized medium being transmitted from each of the pressurized medium chambers to the supply vessel by the compressor when the third and fourth controllable directional valves are in the switched position; an air dryer mounted in the fourth pressurized air line; an intake valve switchable between a base position wherein no throughflow is permitted and a switched position wherein throughflow is permitted; an intake line ending at the intake valve and connecting the input of the compressor to the atmosphere when the intake valve is in the switched position; a discharge valve switchable between a base position wherein no throughflow is permitted and a switched position wherein throughflow is permitted; a discharge line branching off from the fourth pressurized air line at a branch point between the output of the compressor and the air dryer and ending at the discharge valve; and, the supply vessel being connectable to the atmosphere via the air dryer and the discharge line when the discharge valve is in the switched position.
An advantage of the invention is that the air dryer can be mounted in a pressurized air line of the level control system and is at least shielded completely from the atmosphere by the intake valve or by the discharge valve. In this way, the problem is avoided that the air dryer continuously takes up atmospheric moisture from the atmosphere. A further advantage of the invention is that the air dryer is mounted on the compressor output end (that is, on the pressure end of the compressor). This leads to an especially high effectiveness of the air dryer during drying operation. For this reason, the air dryer can have a simple configuration and a small-dimensioned dryer bed. A further advantage of the invention is that even though the air dryer is completely integrated into the closed level control system, pressurized air from the pressurized air supply vessel can be discharged via the air dryer (for its regeneration) into the atmosphere. A further advantage of the invention is that there is a flowthrough of the air dryer during regeneration operation in the opposite direction than during the drying operation. In this way, an excellent regeneration of the air dryer is ensured.
In the closed level control system of the invention, the first to fourth controllable directional valves are mounted in the first to fourth pressurized air lines, respectively; the first to fourth pressurized air lines are cleared in a first switching state of the first to fourth controllable directional valves and blocked in a second switching state of the first to fourth directional valves; the first and fourth pressurized air lines are connected together at a first point between the first and fourth controllable directional valves and the pressurized medium supply vessel and, from the first point, the first and fourth pressurized air lines are connected to the pressurized medium supply vessel via a first common pressurized air line; and, the second and third pressurized air lines are connected together at a second point between the second and third controllable directional valves and the pressurized medium chambers and, from the second point, the second and third pressurized air lines are connected to the pressurized medium chambers via a second common pressurized air line. The advantage of this embodiment is that only 2/2 directional valves are mounted in the four pressurized air lines which provide a simple configuration and are cost effective.
The closed level control system of the invention further comprises: the first and fourth controllable directional valves are combined to form a first composite directional valve; the second and third controllable directional valves are combined to form a second composite directional valve; each of the first and second composite controllable directional valves are switchable between first and second switching states; the first and second controllable composite directional valves can assume at least two switching states; the first pressurized air line is closed with the first controllable composite directional valve and the second pressurized air line is cleared with the second controllable composite directional valve; the fourth pressurized air line is blocked with the first controllable composite directional valve and the third pressurized air line is blocked with the second controllable composite directional valve when pressurized air is to be transferred from the pressurized medium chambers; and, the first and second controllable composite directional valves a
Behmenburg Christoph
Folchert Uwe
Grabherr Werner
Hein Dierk
Westerkamp Helge
Continental Aktiengesellschaft
Ottesen Walter
Siconolfi Robert A.
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