Conveyors: power-driven – Conveyor section – Live roll
Reexamination Certificate
1999-02-22
2001-12-11
Ellis, Christopher P. (Department: 3651)
Conveyors: power-driven
Conveyor section
Live roll
C198S781060, C198S788000
Reexamination Certificate
active
06328154
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a freight loading system such as is used in aircraft to convey in particular containers, pallets or the like within a cargo hold.
DESCRIPTION OF THE PRIOR ART
During the loading and unloading of aircraft, it is important that the objects to be stored in the aircraft or removed therefrom be transported into their places or out of the cargo hold as rapidly but also as reliably as possible. However, such a loading and unloading process must not only be completed in a short time, it must also take place under extremely diverse conditions. This diversity results firstly from the configuration of the objects themselves, which may have various undersurface structures or contents of various weights, and also from the position of the aircraft or of the cargo deck, which can be tilted at various angles because the positions of parked aircraft are not always optimal and can also change depending on the weight of the load. It should also be kept in mind that the bottoms of the objects to be transported can differ in their stability and in the skid-resistance of the material of which they are made. Moisture and dirt play a major role in this regard.
Finally, the operating staff has a large role in the problems at issue here. To save costs, it is desirable to minimize the number of employees, who are furthermore often unskilled and, in particular when pressed for time, may work carelessly.
In conventional systems it is very largely left to the operating staff to determine how roller drive units are controlled, and they usually work with constant conveying parameters (in particular with respect to transport speed, pressure exerted by drive rollers etc.), not taking into account the variations cited above.
The object of the invention is to provide a freight loading system that improves the loading and unloading process while reducing the work required of the operators.
SUMMARY OF THE INVENTION
According to the present invention there is provided a freight loading system for conveying an object on a freight deck of an aircraft comprising
a drive roller unit with at least one drive roller which can be brought into engagement with an undersurface of the object, and with a controllable drive motor that is in operative connection with the drive roller;
a sensing means comprising a measurement roller which can be brought into connection with the undersurface of the object;
at least one measurement sensor connected to and located relative to the measurement roller in order that at least one of the circumferential velocity of the measurement roller, a load imposed on the measurement roller substantially perpendicular to the freight deck, a horizontal force acting on the measurement sensor during braking of the measurement roller, and a torque corresponding to such a horizontal force is converted into measurement signals by the measurement sensor; and
a control means with an operator's console, to which the measurement signals are sent and which is in controlling connection with the drive motor of the drive roller unit in order that operation of the drive motor can be controlled and regulated according to the measurement signals.
It is an important aspect of the invention that the parameters of interest here, which vary from one object to another, are monitored directly or indirectly by the sensing means and the roller drive unit is controlled or regulated accordingly. In particular, the freight loading system in accordance with the invention comprises at least one drive roller unit to convey objects, in particular containers, pallets or the like, on the freight deck of an aircraft and least one sensing means which monitors the parameters of the object that are of interest and/or its momentary state (e.g., whether stationary or moving. Preferably, a plurality of sensing means are provided so that the movement of the objects can be monitored throughout the cargo hold.
When a sensing means or measurement roller is in close spatial proximity to a roller drive unit, if equipped with a rotation-speed sensor it can be used to regulate the speed of the drive motor for the associated roller drive unit in such a way that there is no slippage between the drive roller and the undersurface of the object to be conveyed. This is achieved quite simply by regulating the drive motor to a speed of rotation such that the circumferential velocity of the drive roller corresponds to that of the measurement roller. It is further possible, if at least two sensing means (e.g., reflection light barriers) are disposed close to one another along the transport direction instead of the measurement roller, to calculate a velocity value and adjust the drive motor for the roller drive unit that will next be encountered by the object such that the circumferential velocity of the associated drive roller corresponds substantially to this calculated velocity or, if the object is to be accelerated, is a little higher or, if the object is to be slowed, is a little lower.
Preferably, the control means is so constructed that the maximal transport velocity of an object is adjusted according to its weight or its mass in such a way that heavier objects are transported with lower maximal velocities than lighter objects. The weight or mass of the object could be input manually as a reference value, but this is relatively time-consuming. It is therefore proposed to provide at least one load sensor in the region of the entrance door to the cargo space, by means of which the weight of the object to be conveyed can be determined. In accordance with this reference value, the drive roller units are subsequently driven at higher or lower accelerations or velocities, so that on one hand the loading speed is increased while on the other hand the danger of collision damage in case of braking errors is reduced.
In another embodiment of the invention, in order to determine the weight or mass of the objects to be conveyed the forces that act during their acceleration are measured, from which the values of interest can be derived. This can be done, firstly, by measuring the moments of force acting on the drive rollers when the object is accelerated, or else the measurement rollers can be equipped with brakes and the forces measured that are exerted during the deceleration of moving objects. In the latter case, i.e. when a measurement roller equipped with a brake is used, the amount of braking force applied to this roller when a moving object is to be halted or a stationary one kept in place (e.g., on a sloping freight deck) is preferably adjusted according to the weight or mass of the object to be stopped or retained. By this means, it is possible to minimize both the electrical energy that must be drawn from the on-board supply for braking or retention and the mechanical and thermal stresses on the measurement roller or its brake.
In an embodiment of the invention in which the vertical position of the drive roller relative to the freight deck can be adjusted, the control means is so designed that the relative position of the drive roller depends on the structural characteristics and/or stability of the undersurface of the object being conveyed at the moment. In this case, for example, the maximal permitted force is brought to bear on the bottom of the object to be conveyed by way of the drive roller unit, for which purpose the unit is initially always raised from its lower, resting position into its upper, operating position until the maximal permitted raising force has been reached. As soon as a beam or shoring is detected, the drive roller is lowered, and thereafter it is raised again to the maximal limit. In particular when pallets are being loaded, this feature is helpful.
The sensing means or measurement rollers that are in direct spatial juxtaposition with drive roller units, in particular ahead of and/or after the drive roller in the transport direction, in one embodiment of the invention are used to raise the drive roller when an object arrives at the sensing means, in particular the measur
Ellis Christopher P.
Knobbe Martens Olson & Bear LLP
Sharma Rashmi
Telair International GmbH
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