Aeronautics and astronautics – Aircraft structure – Passenger or cargo loading or discharging
Reexamination Certificate
1999-02-22
2001-07-03
Swiatek, Robert P. (Department: 3643)
Aeronautics and astronautics
Aircraft structure
Passenger or cargo loading or discharging
C198S781060
Reexamination Certificate
active
06254033
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a roller drive unit with sensors and a logical control circuit for use in the motor-powered raising and lowering of drive rollers of the roller drive unit.
DESCRIPTION OF THE PRIOR ART
A known loading system for loading and unloading the cargo hold of an aircraft comprises a plurality of roller drive units. Each of the roller drive units is provided with a drive roller, which when in a raised, operating position conveys a container. Sensors provided in this known loading system, however, merely signal the presence or absence of a container in the region of operation of the relevant drive roller. If there is no container over the roller drive unit, the drive roller is lowered into a resting position.
If a raised drive roller is struck by a container approaching from the side, the roller drive unit can easily be damaged. The presence of even one nonfunctional roller drive unit in a loading system can disrupt the loading process.
In view of the foregoing, the object of the present invention is to increase the reliability of operation of a roller drive unit in a loading system for loading and unloading a cargo hold, in particular in an aircraft, and hence to increase the reliability of a loading system as whole.
SUMMARY OF THE INVENTION
According to the present invention there is provided a roller drive unit for the transportation of freight containers in the hold of an aircraft comprising a drive roller rotatable about its longitudinal axis; an electric motor means linked to the drive roller in order that the drive roller can be retracted and can be raised into an operating position for engagement with a freight container to be transported by operation of the electric motor means; a plurality of sensing means disposed in a spaced relationship in a ring around the drive roller in order that a direction of movement of a freight container approaching the drive roller can be determined; and a control means operationally connected to the sensing means and to the electric motor means in order that the drive roller can be raised into the operating position and can be retracted in accordance with a signal received by the control means from the sensing means.
The invention therefore protects the drive roller of a roller drive unit, which is otherwise is largely unprotected, from hard mechanical impacts produced by the freight containers. In particular, by disposing the sensing means on the left and/or right of the drive roller with reference to the conveying direction of the drive roller, the sensing means can signal when a container is approaching the drive roller from the side. Where appropriate, the sensing means signal this to a logical control circuit that causes the drive roller to be rapidly lowered into its protected retracted position and/or rotated so that the conveying direction of the drive roller corresponds to the direction of transport of the approaching container.
A monitoring means monitors the specific electrical signals emitted by the sensing means in the case that a container is approaching and outputs them to a logical control circuit connected to the monitoring means. The control circuit determines the temporal sequence in which the sensing means are passed by the container and sends out a trigger signal when a container is approaching the sensing means near the drive roller at an unfavorable angle or from the side.
Advantageously, in one embodiment of the invention the logical control circuit in addition determines the angle, again with reference to the conveying direction of the drive roller, at which a container is approaching the roller drive unit or the drive roller. If the container is found to be moving within a predetermined range of angles such that, if no countermeasures were taken, it would strike the drive roller in a harmful way, this situation is detected in time by the control circuit with the aid of the sensing means and the control circuit sends out a trigger signal that activates the electric motor, which retracts the drive roller of the roller drive unit from the region affected by the container in time to prevent collision, and lowers the roller into a resting position.
Alternatively or in addition, the trigger signal from the control circuit can activate an actuating means such as a second electric motor which rotates the drive roller or a carrier element that carries the roller drive unit in such a way that the conveying direction of the drive roller largely coincides with the angle at which the container is approaching the roller drive unit.
The suitably positioned sensing means in combination with the logical control circuit additionally detect whether a container is over the roller drive unit or not, or the direction from which the container is moving toward the roller drive unit. As a result, the possibility that the roller drive unit might be struck from the side is excluded. If an object passes simultaneously over two individual sensing means on either side of the drive roller, the latter can be raised and actuated or remain raised and continue to operate. If the object passes over only one of these sensing means, the drive roller can remain retracted. If the two sensing means are passed over in sequence, the drive roller must be rapidly lowered and retracted or, if already retracted, must not be raised into an operating position. Preferably the drive roller is lowered into its retracted position as soon as the sensing means no longer signal the presence of a container.
The sensing means employed here preferably comprise optical sensors, such as reflection photoelectric barriers.
The invention will now be described by way of example with reference to the accompanying drawings.
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Durrwaechter Martin
Huber Thomas
Kieser Benedikt
Urch Matthias
Knobbe Martens Olson & Bear LLP
Swiatek Robert P.
Telair International GmbH Obere Tiefenbachstrasse
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