ARRANGEMENT FOR AIR CONTROL

The present invention relates to an arrangement for air control in chambers capable of being inflated against the effect of a flexible force, such as seals which are intended to be inflated at loading bay openings and similar and to be brought into contact with a vehicle parked at the opening or driven partly into the opening so as to provide a seal against the vehicle.

The invention is intended first and foremost to be applied in conjunction with entrance seals installed at loading bay openings (eg. US-A-4,044,510) and similar. Entrance seals of this kind more often than not consist of one or more air chambers resembling bellows suspended around the loading bay opening in question, into the interior of which air is blown preferably by means of a low-pressure fan, thereby causing the seal to inflate in a direction away from the edge of the loading bay opening and towards a vehicle situated at the opening or driven partly into the opening. The fan is usually caused to operate for as long as it is wished to maintain the seal between the edge of the loading bay opening and the vehicle. When it is wished for the seal to cease so as to permit the vehicle to be driven away, the fan is usually switched off, and the air chamber is emptied of air by means of flexible compressing devices, the forces of which acting upon the seal are such that they will displace the seal towards its compressed position when the effect of the fan ceases, but that the force generated by the fan will exceed the compressing force when the fan is operating.

The object of the invention is to provide an arrangement for air control in conjunction with the inflation and evacuation of the seal, which is of the simplest possible design and yet is reliable and inexpensive to manufacture. The wish is to achieve through the invention an arrangement for the air control which exhibits a control system which is as simple as possible, with the smallest possible number of sensors and operating controls.

This is achieved by an air control arrangement in accordance with the invention which is characterized essentially in that there discharges into the internal cavity of the inflatable chamber a large-section channel containing a damper so arranged as to bring the inside of the air chamber into open communication with an inlet channel containing a fan, preferably of the low-pressure type, for the purpose of inflating the chamber, and alternately with the atmosphere for the purpose of evacuating the chamber, for which purpose the damper is controlled in such a way by the air flow of the fan that it is caused to change over to the position which interrupts the open communication between the inside of the chamber and the atmosphere as the fan approaches its operating speed, usually its maximum speed, in this way opening the communication via the fan for the purpose of inflating the chamber, and vice versa, i. e. to change over to the position which opens up the communication between the air chamber and the atmosphere as the speed of the fan decreases.

An illustrative embodiment of the object of invention is described in the following with reference to the accompanying drawings, in which :

Fig. 1 shows an air control arrangement executed in accordance with the invention in its inactive mode, i. e. in a position in which the air fan is stationary and the communication between one element, for example an inflatable entrance seal to which the air control arrangement is connected, and the atmosphere is open ; and

Fig. 2 shows the same air control arrangement in its operating mode, in which the fan is forcing air into the air channel in question.

The designation 1 is used in the drawings in respect of the air control arrangement as a whole, which is connected to an air chamber 2 via a connecting flange 3 or similar. The air control arrangement consists of an essentially «T "- shaped pipe, the part of which corresponding to the cross-piece of the « T" consists of an inlet connection 5 and an outlet connection 6, whilst the component which corresponds to the upright of the « T and is identified by the designation 7 forms a communication between the interior of the housing 1 and the air chamber 2. The designation 8 is applied to a damper which is pivotally attached by means of articulations 9 resembling hinges to that wall of the housing 1 which is situated opposite the communication connection 7. The damper 8 is acted upon by two tensioning springs 10 which extend between the damper 8 and the wall of the housing and which attempt to hold-the damper in the position illustrated in Fig. 1, in which the communication between the connections 7 and 6 is open, i. e. the communication between the interior of the air chamber 2 and the atmosphere A is open, whilst the communication between the inlet connection 5 and the communication connection 7 is closed. When the fan 4 is rotating at its operating speed, the force of the air flow generated by the fan will overcome the force of the springs 10, causing the damper flap 8 to swing over into the position illustrated in Fig. 2, in so doing interrupting the communication between the communication connection 7 and the outlet connection 6, whilst the communication between the inlet connection 5 and the communication connection and thus the interior of the air chamber 2 is open instead. The housing 1 should preferably exhibit a comparatively large internal cross-section, so that both the air which is forced in by the fan 4 and the air which flows out of the air chamber 2 are able to pass through the housing 1 with low resistance.

When it is wished to fill the air chamber 2 with air, the fan 4 is started up, and the pressure of the air flow will cause the damper flap 8 to swing from the inactive position shown in Fig. 1 against the effect of the springs 10 into the position shown in Fig. 2, in which the communication between the inlet connection 5 and the interior of the air chamber 2 via the communication connection 7 is opened. The fan 4 should preferably be left running for as long as it is wished to keep the air chamber 2 inflated, i. e. in the case of a seal at a loading bay door for as long as it is wished to maintain the seal between the edges of the loading bay opening and the vehicle which is to be loaded and/or unloaded. The tension of the springs 10 should preferably be so dimensioned as to enable them to cause the damper flap 8 to swing back into the position shown in Fig. 1 as soon as the speed of the fan decreases and the pressure of the air flow produced by the fan against the damper flap 8 falls. When it is no longer wished to maintain the pressure inside the air chamber 2, i. e. in the case of a seal at loading bay openings when it is wished to permit the seal against the vehicle to cease so that the vehicle can be driven away, the power supply to the fan is interrupted, then the damper flap 8 will immediately swing over into the position shown in Fig. 1 and in so doing will open fully the communication between the inside of the air chamber 2 and the atmosphere A. What this means is that air will be able to flow more or less immediately from the inside of the air chamber 2, i. e. whilst the fan is still rotating at a comparatively high speed. It is thus possible, by using the air control arrangement in accordance with the invention, for both the inflation of the air chamber 2 and the evacuation of same to take place rapidly and efficiently using a single fan and with extremely simple control and monitoring devices, all that is required for the inflation and evacuation of the air chamber being simply the respective closing and opening of the power circuit to the fan motor in question. In the illustrative embodiment shown here the force which attempts to move the damper flap 8 into the position shown in Fig. 1 is provided by springs. It is also possible, of course, within the context of the invention, for this force to be provided by other means, such as cables with weights attached, lever arms and similar. The damper illustrated here is mounted in an articulation 9, but it is also possible, of course, within the context of the invention, for the damper to be capable of parallel displacement along the inlet and outlet connections 5 and 6 from one side to the other of the orifice of the communication connection 7 which discharges into the interior of the housing 1. The housing 1 is shown in the drawings to have rectangular cross-section, although it can, of course, have some other cross- sectional form within the context of the invention. Neither is it necessary to arrange the fan 4 directly inside the housing 1. This can, of course, be situated at some other point in a line connected to the inlet connection 5. The springs 10 may be adjustable with regard to their spring tension in order to permit the appropriate variation of the flexible forces acting upon the damper flap 8. Similarly, the speed of the fan drive motor may also be variable. In the embodiment illustrated here the side walls of the communication connection constitute stops for the swinging end of the damper plate 8 at its discharge opening into the housing 1, although these stops may, of course, also be executed in some other way, for example inside the inlet connection 5 and the outlet connection 6.

The invention is not restricted to the examples described above and illustrated in the drawings, but may be varied with regard to its detailed aspects within the context of the following Patent Claims without in any way departing from the underlying idea of invention.