Land vehicles – Suspension modification enacted during travel – Riding or suspension height
Reexamination Certificate
2002-03-15
2003-09-23
Culbreth, Eric (Department: 3616)
Land vehicles
Suspension modification enacted during travel
Riding or suspension height
C280S006150, C280S006157, C280S006159, C280S124160
Reexamination Certificate
active
06623016
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relates to a control system for lifting and lowering the body of an air-suspended vehicle. With such systems, the desired distance between the body of the vehicle and the axle of the vehicle may be automatically adjusted. Additionally, it may be desired to design the system in a way that the body may be lifted and lowered, respectively, in an arbitrary way. Such an arbitrary adjustment may serve to adapt the height of the vehicle to the height of a loading platform to load or to unload the vehicle. The control system may also be designed in a way that different heights of the body with respect to the axle may be stored for later use. The system may be applied to motor vehicles as well as to trailers.
BACKGROUND OF THE INVENTION
A control system is known from German Patent No. 35 06 179 C2 The known control system includes a level control valve which serves to adjust the desired distance between the body and the axle of the vehicle when the system works correctly. The level control valve is combined with a path sensor to form one common unit. The path sensor sends an electric signal to an electronic control unit, the electric signal corresponding to the distance between the body and the axle of the vehicle. A switching valve unit is arranged downstream of the electronic control unit, the switching valve unit including a switching valve having four positions, namely a lifting position, a lowering position, a driving position and a stop position. The switching valve is designed in a two circuit way, meaning it serves to operate two air-suspension bellows, or two air-suspension bellow circuits. The electronic control unit is connected to a selector switch such that it allows for arbitrarily lifting and lowering the body. Arbitrarily lifting or lowering the body with respect to the axle may be desired to adapt the height of the vehicle to an existing loading platform, for example. Arbitrarily lifting and lowering the body of the vehicle is only possible during correct electric power supply of the known control system. Since electric supply usually is interrupted when trailers are parked at a loading platform, arbitrarily lifting and lowering is then no longer possible with the known system. In the case of power supply being interrupted—no matter whether this occurs due to a defect or consciously caused by the user—the switching valve of the known system remains in its present position. Consequently, the body cannot be lifted or lowered with respect to the axle in the known system. In the known system, this problem concerning a trailer being parked at a loading platform can only be solved by making sure that there always is correct electric power supply of the known control system.
Another control system for lifting and lowering the body of an air-suspended vehicle including level control is known from German Patent Application No. 43 27 764A1. The vehicle additionally includes a lifting axle. The known control system includes an electronic control unit including a switching valve unit. The switching valve unit includes a plurality of switching valves to be electrically controlled and to be controlled by a spring. The known arrangement is chosen such that the position of the switching valves that has been electrically caused is maintained even without power supply. In this way, the lifting axle remains in its present position even when power supply is turned off, or when power supply fails. In this way, reduced consumption of power is achieved. However, when power supply fails, lifting and lowering of the body of the known vehicle is not possible.
SUMMARY OF THE INVENTION
The present invention relates to a control system for lifting and lowering the body of an air-suspended vehicle. The vehicle—which may be a motor vehicle or a trailer, for example—includes an axle and level control. The system includes a source of compressed air, a plurality of air-suspension bellows each being associated with at least one axle and being designed and arranged to adjust a desired distance between the body and the axle, a path sensor being designed and arranged to sense and determine the distance between the body and the axle and to create and deliver a respective electric signal, a switching valve unit having a lifting position, a lowering position, a driving position and a stop position, an electronic control unit being designed and arranged to control the switching valve unit in response to the electric signal delivered by the path sensor, a first conduit branch being located between the source of compressed air and the air-suspension bellows, a second conduit branch being located between the source of compressed air and the air-suspension bellows, at least one level control valve being located in the first conduit branch, and at least one locking valve being located in one of the conduit branches and including a spring, the locking valve being designed and arranged to be electrically switched to reach a first position and to be switched by the spring to reach a second position. The first conduit branch is designed and arranged to be activated in the second position, and the second conduit branch being designed and arranged to be activated in the first position. The present invention also relates to a controlling installation and to a control apparatus for lifting and lowering the body of an air-suspended vehicle.
The novel control system may also be used on trailers, and it is designed to be automatically active even when there is no power supply. It is important that the locking valves may be electrically switched to reach a first position, and that they may be mechanically switched to reach a second position. In this way, the first (“electrical”) position is only taken during correct power supply, while mechanical-pneumatic operation is used during interruption of power supply. The second position is the fallback position, or—in other words—the fallback plane. Depending on the fact whether the control system operates electrically or mechanical-pneumatically, the respective other conduit branch is caused to be ineffective—or at least its effects are substantially reduced—in a way that it does not have a substantial influence on the compressed air prevailing in the air-suspension bellows. The locking valve has two positions of which one is a locking position in which the connected parts of the conduits are locked with respect to one another. The second position is a passage position or a release position in which the respective connected conduit parts are interconnected.
A first embodiment of the novel control system includes a locking valve being located in the conduit branch upstream or downstream of the level control valve. This locking valve has a passage position to be caused and adjusted, respectively, by a spring, and a locking position to be electrically adjusted. It is especially preferred to arrange the locking valve downstream or after the level control valve such that the switching valve unit may be arranged in the other conduit branch. The first conduit branch in which the level control valve is arranged and which may extend to the air-suspension bellows is locked during correct power supply such that the switching valve unit may operate the air-suspension bellows without any loss of air. However, it is also possible to arrange the locking valve in the first conduit branch in which the level control valve is arranged and upstream or in front of the level control valve. A slight loss of compressed air occurring at the level control valve due to pushing movements and vibrations during travel of the vehicle is acceptable.
Another possibility is to arrange the locking valve in the second conduit branch in which the level control valve is not arranged. The locking valve then has a locking position to be caused by the spring, and a passage position to be electrically adjusted. When the locking valve is arranged in the conduit branch in which the level control valve is not located, it has to have an inverse design in a way that its pos
Blanz Roland
Sulzyc Georg
Culbreth Eric
Haldex Brake Products GmbH
Thomas Kayden Horstemeyer & Risley
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