Patent Application
20100262341
The invention relates to a method for controlling a displacement device for a fifth wheel coupling disposed on a tractor vehicle, according to the features in the claims. The invention further relates to a particularly suitable control system for carrying out the inventive method for a displacement device.
A displacement device of the general type contemplated is known, e.g. from DE 10 2005 060124 A1. With the aid of a motorized drive unit a carriage bearing the fifth wheel coupling can be displaced in the longitudinal direction of the tractor vehicle on two parallel guide rails, and can be locked in a prescribed position. When the vehicle is traveling at rapid Autobahn speeds without appreciable curves, it is desirable for the fifth wheel coupling to be positioned as close as possible to the tractor cab, in order to minimize the gap between the cab and the front of the semi-trailer and thereby minimize vortex formation in this region. According to the cited known patent application, the control device of the displacement device is connected to the vehicle control system, so that information relating to the vehicle speed can be retrieved and thus in normal operation the gap between the tractor and the semi-trailer can be adjusted appropriately. However, with this arrangement there is a problem in that when negotiating a curve of relatively short radius the semi-trailer can swing past the cab under conditions of minimization of the gap between the tractor and semi-trailer, and thereby a corner of the semi-trailer is apt to strike against the cab. This problem also tends to arise in situations of panic braking sudden intense braking without compensating maneuvers; the panic braking can be taken into account by evaluation of a braking signal which is input to the control device and converted into an actuation of the displacement device to bring about extremely rapid rearward movement of the carriage so as to increase the length of the gap.
Other state of the art is disclosed in DE 10 2004 045662 A1, wherein the displacement device is associated with a position sensor which determines the position of the carriage. The signal from the position sensor is sent to a control device wherewith, if the gap between the cab and the front of the semi-trailer is too short, the control device may actuate the drive unit of the displacement device and thereby displace the carriage rearward.
However, in practice it has been found that inputs in the form of braking signals and vehicle speed signals are not well suited to timely respond to panic braking. The reaction times required for the control system are extremely short, often insufficient for the system to timely displace the fifth wheel coupling into a rearward position and thereby establish the necessary distance between the cab and the front of the semi-trailer.
Accordingly, the underlying problem of the invention was to devise a method and a control system whereby timely establishment of a sufficiently long gap between the tractor and the associated semi-trailer is possible.
This problem is solved according to the invention by a method wherein distance measurement is carried out to detect an obstacle disposed ahead of the tractor, and the measurement signal is processed in the control device to yield a control signal, which is employed to actuate the motorized drive unit and/or the adjusting member.
With displacement devices which are frequently used, the carriage is displaced on two parallel guide rails by means of a motorized drive unit, such as, e.g., a hydraulic cylinder, and, after the prescribed position is reached, the carriage is fixed on both sides to the guide rails. Typically, the fixing means are comprised of an adjusting member e.g. a pneumatic or hydraulic cylinder, which moves locking pieces in the direction of the guide rails, which pieces form-interlockingly engage the guide rails. In the event of, e.g., intense braking or collision, the motorized drive unit releases this locking of the carriage.
Instead of a form-interlocking lock mechanism, it is also possible for the motorized drive unit to be appropriately dimensioned such that one can dispense with additional form-interlocking elements. With such an embodiment, the adjusting member will be understood to comprise a shutoff valve which traps the fluid present in the interior of the cylinder.
When the vehicle is traveling at high Autobahn speeds, the semi-trailer will be drawn close to the tractor cab, by means of the displacement device, wherewith the gap between the cab and the front of the semi-trailer will be held at its minimum length. This will minimize vortex formation and thereby will minimize fuel consumption. In the event of a sudden steering maneuver, the fixing of the carriage will be released, and the carriage will be displaced rearward on the guide rails. Using the inventive method, the road path ahead of the vehicle is monitored and obstacles in that path are detected. In this way it is possible to increase the length of the gap between the cab and the front of the semi-trailer even before the driver reacts.
Preferably the method of achieving this is that, when a prescribed first reaction distance to the obstacle is reached, the control device switches the motorized drive unit and/or the adjusting member into a readiness state. If the driver then initiates intense braking, possibly accompanied by a strong steering maneuver, the rearward displacement of the carriage can be effected without a time delay.
In the readiness status, one may cause, e.g., the startup of a hydraulic pump of the motorized drive unit. This makes the necessary system pressure available to the motorized drive unit which typically is a hydraulic cylinder, in order to move the carriage bearing the coupled semi-trailer rearward under circumstances of intense braking of the vehicle.
Advantageously, when a second, shorter reaction distance is reached, the fixing of the carriage is released, and the carriage is displaced by the motorized drive unit into a rearward position. Under this scenario, the driver still has not reacted, and the tractor and semi-trailer combination continues to approach the obstacle with undiminished speed. In this phase, the carriage is automatically forced into a rearward position on the guide rails, because at this point it is apparent that intense braking or a sharp avoidance maneuver will follow.
Advantageously, the carriage will be fixed in the rearward position by means of the adjusting member. In particular, additional security can be achieved if locking pieces disposed on the adjusting member form-interlockingly engage the guide rails, wherewith the carriage will not be exclusively held in place by the motorized drive unit.
The invention is also realized in the form of a control system in which the control device is connected to a distance sensor which, when an obstacle is present ahead of the tractor vehicle, generates a measurement value, and said control device cooperates with the drive unit and/or the adjusting member.
Preferably the distance sensor is a component of a distance measuring system of the vehicle. The distance measuring system serves to detect obstacles, and when the vehicle continues to approach an obstacle the distance measuring system initiates braking without a reaction by the driver. If such a distance measuring system is present, the control device can receive the necessary measurement value from that system.
The distance sensor may be a radar, lidar, or infrared sensor. The underlying principle of radar involves electromagnetic waves in the radio frequency range which are sent out in a so-called primary signal and when reflected by objects a secondary signal is generated which is received and evaluated. Lidar stands for “light detection and ranging”, also used for measurement of distances and speeds; it is analogous to radar, but instead of radio waves as in radar, laser light is used.
The distance maintenance system may also be a component of a path following system, or may comprise a path following system. In this case the lane line comprises the obstacle. The path following system reacts by sending out a signal when the tractor moves away from the lane line without any appreciable steering action. This signal can also be utilized to shift the displacement system into a readiness state and/or to initiate a displacement of the carriage into a rearward position, because, after the vehicle departs from the lane line, e.g. due to driver fatigue, frequently this is followed by a sudden appreciable steering action, in order to bring the tractor back into accord with the lane line.
For the sake of better understanding, the invention will be described in more detail hereinbelow with reference to three Figures.
The displacement device 1 is illustrated in an enlarged bottom view in
In
The inventive control system illustrated in
If the driver does not show an appropriate reaction to obstacle 9 before the distance is reduced to a second reaction distance X2, the carriage 5 bearing the front part of the semi-trailer 14 is retracted rearward by the motorized drive unit 7, and the maximum gap length W2 is established. After the maximum gap length W2 has been effected, extreme avoidance maneuvers are possible, because the front 15 of the semi-trailer can swing past the tractor cab 13 without striking it.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2009 002 335.6 | Apr 2009 | DE | national |
