Land vehicles – Wheeled – Running gear
Reexamination Certificate
1999-08-04
2001-12-25
Mai, Lanna (Department: 3619)
Land vehicles
Wheeled
Running gear
C280S124157, C280S005514, C280S006150, C280S791000, C280S791000, C280S843000, C267S064280, C267S064110
Reexamination Certificate
active
06332623
ABSTRACT:
INTRODUCTION AND BACKGROUND
The present invention relates to a level adjustment device for vehicles with a plurality of air springs, by which a vehicle body is furnished with suspension on at least one vehicle axle, which has the following characteristics:
a source of compressed air, which, for the purpose of filling the air springs, can be connected to the air springs via an air dryer;
the air dryer, for the purpose of filling the air springs, is connected on one side to the air, springs through a check valve that is open to the air springs;
each air spring, for the purpose of emptying them, can be connected through the air dryer and through a pneumatically controlled first distribution valve to the atmosphere, wherein the pneumatic control input of his distribution valve is then impinged through a second distribution valve with the pressure in the air springs against a restoring force acting on the pneumatic control input;
the pneumatic control input of the pneumatically controlled first distribution valve, for the purpose of ending the emptying process, can be connected to the atmosphere.
A level adjustment device of the type mentioned in the introduction is known from German patent document DE 35 42 975 C2. The level adjustment device known from this publication can be characterized as advantageous in the respect that the distribution valve through which the air escapes into the atmosphere through the air dryer for the purpose of emptying the air springs is configured as a pneumatically controlled distribution valve. Consequently, high switching forces can be exerted on this distribution valve and great flow cross-sections can be engaged using the compressed air in the air springs. If by chance the distribution valve ices up as a consequence of moisture in the air at low temperatures, the switching of the distribution valve is nevertheless possible. With the level adjustment device known from DE 35 42 975 C2, it is further seen as advantageous that in their normal condition (i.e. when the air springs are neither filled up nor empty) the air springs are separated from the air dryer on one side by a check valve open to the air springs and on the other side by an electrically controlled distribution valve, so then no air can flow from the air springs to the air dryer. Consequently, it is possible to arrange between the air springs and the air dryer a pressure sensor to which each air spring can be connected to measure pressure without the possibility of air flowing out of the air springs into the air dryer. This would lead to an undesirable loss, in pressure in the air springs.
However, it must be stated with the level adjustment device known from German patent document DE 35 42 975 C2 that, in emptying an air spring, the air is routed through the electrically controlled distribution valve, which, in the normal condition, separates the air springs from the air dryer. Since with electrically controlled distribution valves only small flow cross-sections can be engaged at a justifiable expense, a rapid emptying of the air springs, and a correspondingly rapid lowering of the vehicle (e.g. with the vehicle parked) is therefore not possible.
It is therefore an object of the invention to produce a level adjustment device in which the air springs are completely separated from the air dryer in the normal condition and in which a rapid emptying of the air springs is possible.
SUMMARY OF THE INVENTION
The above and other objects of the present invnetion can be achieved by a device described herein which features an air dryer connected on the other side to the air springs through a pneumatically controlled third distribution valve, wherein the pneumatic control input of this distribution valve is then impinged upon with the pressure in the air spring against a restoring force acting on the pneumatic control input.
The advantages achieved with the invention are to be seen in particular in the fact that the air springs are emptied through a pneumatically controlled distribution valve arranged between the air springs and the air dryer to which large flow cross-sections can be conducted. Because of this, a rapid emptying of the air springs is possible. Furthermore, in the normal condition of the level adjustment device, the air springs are completely separated from the air dryer. Consequently, by using a pressure gauge it is possible to measure the air pressure without a volume of air flowing from the air springs into the air dryer, thus leading to an undesirable loss in pressure in the air springs.
A further advantage of the invention is to be seen in the fact that, during the emptying, of an air spring, air does not continually flow through the second controllable distribution valve. Therefore, losses in air pressure at this valve do not result. Consequently, the full static air pressure of the air springs is present at the control input of the pneumatically controlled first distribution valve, so that high switching forces can be generated there. By contrast, with the level adjustment device known from DE 35 42 975 C2, during the emptying of an air spring, air continually flows through the second controllable distribution valve. This is because, on one side, the control input of the pneumatically controlled first distribution valve is controlled by this second distribution valve, and, on the other side, the air from the air spring flows into the air dryer; for this reason a continual loss in pressure in the static air pressure results, so that the full air pressure is not applied at the control input of the pneumatically controlled first distribution valve.
According to another configuration of the invention, the pneumatic control input of the first control valve can be connected to the atmosphere through the second controlled distribution valve for the purpose of ending an emptying process. The advantage of this additional configuration is to be seen in the fact that no separate valve needs to be provided for venting the control input of the first distribution valve into the atmosphere. Furthermore, this function is integrated into the second distribution valve.
According to another configuration of the invention, the pneumatic control input of the third control valve is impinged with the pressure in the air spring through the second controlled distribution valve for the purpose of emptying the air spring. The advantage of this additional configuration is to be seen in the fact that no separate valve needs to be provided through which the pneumatic control input of the third distribution valve is impinged with the pressure in the air spring during the emptying of the air spring.
According to another configuration of the invention, the pneumatic control input of the pneumatically controlled third distribution valve can be connected to the atmosphere after an emptying process. The advantage of this additional configuration can be seen in the fact that the pneumatically controlled third distribution valve can be set back into the switching condition in which it blocks the route from the air spring to the air dryer by routing the control input to the atmosphere (i.e. in the normal condition).
According to another configuration of the invention, the pneumatic control input of the pneumatically controlled third distribution valve can be blocked from the atmosphere by the second controllable distribution valve. The advantage of this additional configuration is to be seen in the fact that the pneumatic control inputs of the first and third distribution valve can be blocked from the atmosphere by the same distribution valve and as a result less distribution valves are needed, with resulting cost savings.
According to another configuration of the invention, the pneumatically controlled first distribution valve and the pneumatically controlled third distribution valve are brought together into one pneumatically controlled distribution valve. The advantage of this additional configuration is to be seen in the fact that two separate pneumatically controlled distribution valves do not have to be prov
Behmenburg Christof
Westerkamp Helge
Continental Aktiengesellschaft
Mai Lanna
Royal, Jr. Paul
Smith , Gambrell & Russell, LLP
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