GB2080379A - Doors - Google Patents

Abstract

The invention provides a flexible strip door to protect a relatively large opening from excessive heat loss. The door comprises at least one first section comprising a plurality of flexible strips 12' hanging from a fixed support, at least one second section comprising at least one flexible strip 12 hanging from a movable support, means to move the or each second section away from the centre of the door and towards one side, if necessary at least partially to overlap a corresponding first section, thereby providing an open passage through the doorway, a detector positioned to detect an object requiring an open passage through the doorway and means operable by the detector to activate the means to move the or each second section. <IMAGE>

Description

SPECIFICATION Doors The present invention relates to doors, in particular to doors which protect an opening where it is necessary for entrance or exit to be obtained without necessarily moving the whole door.

In the case of relatively large openings in factories, typically such as those openings in rear loading bays, there is a need to protect against excessive air movement and/or excessive heat loss in the working space which the opening serves as a doorway. In one prior art arrangement which attempts to meet this need a multiplicity of flexible plastics strips are hung from the door lintel. Such strips are usually of transparent P.V.C.

and serve to enable the doorway to be broached by personnel with or without a machine such as a pallet or fork lift truck without necessarily moving the whole door.

However, known flexible strip doors suffer from the disadvantage that where the load carried on say a fork lift truck comprises of a number of light items, individual items can be moved or displaced as the truck moves through the door strip curtain.

Also, the strips tend to drape themselves around the operator as the load passes through the doorway and, besides causing annoyance, can occasionally cause minor injury. In addition, since the centre of the doorway is the section which is used the most the strips in the centre tend to become scratched or torn. This can result in a loss of transparency with a consequent loss of vision through the door or to tearing away of part of one or more strips. Thus, either the door may lose the advantage of transparency with a consequent rise of incidents in the doorway which otherwise might be avoided or heat losses may be increased.

I have now found surprisingly that if a flexible strip door is divided into a plurality of sections and at least one section is arranged so that it is automatically moved out of the way of a person or object passing through the doorway, the above disadvantages are substantially avoided.

Accordingly, the present invention provides a flexible strip door, which door comprises at least one first section comprising a plurality of flexible strips hanging from a fixed support, at least one second section comprising at least one flexible strip hanging from a movable support, means to move the or each second section away from the centre of the door and towards one side, if necessary at least partially to overlap a corresponding first section, thereby providing an open passage through the doorway, a detector positioned to detect an object requiring an open passage through the doorway, and means operable by the detector to activate the means to move the or each second section.

In a door according to the invention there may be any suitable number of first and second sections such as two first sections arranged on either side of a single central second section.

Preferably, however, the door comprises two first sections arranged on either side of two side-byside central second sections, each second section being movable to overlap an adjacent first section.

While it sometimes may be convenient to provide a second section or sections comprising one strip, it will usually be preferred that each second section should comprise a plurality of flexible strips, the strips typically being of uniform size across the door. However, where the second sections comprise one strip, that strip is preferably much wider than the fixed strips. Thus, for example, typically a flexible strip door according to the invention may comprise strips having a width of from 9" to 1 2", although where a single strip is employed that may be say 24" wide.

Depending on the degree of exposure the strips may be overlapped to a greater or lesser degree.

Preferably, the strips are overlapped at least by about 50% of their area, although for areas of high exposure overlaps of up to about 100% may be employed. The number of strips employed will depend on the size of doorway, although a minimum number will typically be about 20 strips i.e. four sections of five each.

The flexible strips of the door of the invention preferably comprise a plastics material and more preferably the flexible strips comprise polyvinylchloride. P.V.C. strips of a quality suitable for use externally are available commercially in a variety of widths and thicknesses.

The flexible door strips of the first and second sections may be hung from the frame of the doorway in any convenient manner such as by hooks or loops or brackets, provided each first section is fixed and each second section is movable. Typically, the strips of the or each first section may be hung on hooks from a supporting element fixed to the door lintel in a known manner.

Preferably, the means to move the or each second section includes a conveyor moving in a continuous path, typically a continuous path from adjacent one edge of the door to adjacent the other edge and back again. In one particularly preferred arrangement two second sections are hung from a continuous conveyor e.g. each on its own supporting element, so that one second section is movable by a portion of the conveyor which moves from the centre of the door to one edge thereof and the other second section is movable by another portion of the conveyor which moves from the centre of the door to the other edge thereof. Preferably, the conveyor comprises an endless chain which may be driven by an electric motor disposed to one side of the door lintel through a suitable gear arrangement.

The detector may comprise any device or apparatus which can be positioned at or adjacent the door to detect an object requiring an open passage through the doorway and which can operate means to actuate the means to move the or each second section. Preferably, the detector is one which produces an electrical signal and the means to activate the means to move the or each second section comprises at least one electrically operable switching device such as a relay, In one preferred embodiment the detector is an induction loop disposed beneath the door and extending outwards to the front and rear of the door in a plane substantially normal to the door plane. Such a detector can detect metal objects such as a pallet or fork lift truck, but may be selected or adjusted not to be operable by small metal objects carried on the person.

In another preferred embodiment the detector is a detector of electromagnetic radiation, and the door arrangement may if necessary include means to generate a beam of electromagnetic radiation at, e.g. directed to, the front and rear of the door whereby the presence or absence of an object to the front and rear of the door may be detected by any radiation which the object emits of itself or by the presence or absence of reflected or interrupted radiation. In this arrangement the generator and detector are preferably a transmitter and a receiver of microwaves respectively where it is desired to detect vehicles, or an infra red detector on its own may be used where it is desired to detect personnel.

Whatever the nature of the detector it is preferred to provide control means to allow adjustment of the level of detector signal whereby the means operable by the detector to activate the means to move the or each second section can be set to an active function above a minimum threshold. For example, the control means may be such as can allow the detector to ignore objects below a particular size whereby personnel and machines may be differentiated and the second section(s) of the door activated to move only by the latter.

The invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a view from one side of a flexible strip door protecting a doorway, with the strip hangings being omitted for simplicity; Figure 2 is a cross-section through the lintel at line i--I of Figure 1 with all but one of the fixed flexible strips omitted; Figure 2(a) shows in detail the top edge of a fixed strip; Figure 3 shows the track arrangement for the moving flexible strips; Figure 3(a) shows in detail one form of hanging arrangement for the moving strips; Figures 4(a) to 4(c) show in diagrammatic form the operation of a door according to the invention; and Figure 5 is a block diagram showing the operation and control sequence.

Referring to the drawings, a door according to the invention is disposed in a doorway 11 and comprises two sections each comprising movable strips 12 and two sections each comprising fixed strips 12'. The strips 12 and 12' are composed of external quality PVC materials and are overlapped to a degree which gives the desired draught exclusion and the necessary minimum heat loss when the door is in the closed position. When the door is closed the two strips 12 adjacent each other at the centre of the doorway may abut or overlap.

Each movable strip 12 is hung suspended from the door lintel 13 via a continuous chain 14 (Figures 2, 2(a), 3 and 3(a)) disposed in a housing channel 15 e.g. a Henderson chain and channel.

The chain 14 is carried on a wheel 16 and a gear 17 and moves around wheel 16 when driven by gear 17 via the axle of an electric motor 1 8.

Although gear 17 is shown for simplicity as a single gear in practice the arrangement will comprise a series of gears forming a gearbox which cooperates with the electric motor drive in a suitable manner.

The strips 12 are hung suspended in two sections, each of which may comprise a number of strips 12 selected to afford the required size of opening through the doorway when the strips 12 are moved to overlie the strips 12'. Thus, for example, as shown in Figure 1 there may be two sections of strips 12 each comprising five strips, together with two sections of strips 12' each comprising five strips, although as shown in Figure 3 there could be two movable sections each comprising less than five strips 12. Since, the strips 12 and 12' may typically have a width of from 9" to 12" in order to provide a minimum 4 ft. opening and maximum strip overlap in practice there will be two sections each of five movable strips 12 and five fixed strips 12' at the minimum.

As shown in Figure 2, the strips 12 are hung via pins 21 on an elongated bracket 22 composed, for example, of extruded aluminium section, the bracket 22 in turn being suspended at each end from chain 14 by studs 23.

As shown in Figure 3(a), each stud 23 may be a threaded stud 23' which passes at its lower end though a hole in the horizontal portion of the bracket 22, where it is retained by a nut 23". At its other end the stud passes through a link 31 of the chain (which may be specially adapted for the purpose) and again is retained by a nut 32.

Also, as shown in Figure 2, the strips 12' are hung via hooks 25 from a bracket 24 fixed to the lintel. Again, bracket 24 may comprise extruded aluminium section, and the hooks 25 typically have one threaded end carrying a nut 33. The hooks 25 each pass down through a hole in bracket 24, and through a hole 35 in a plate 34 fixed to the top edge of each strip 12' by a pin 36.

As shown in Figure 2(a) each strip 12' typically has two plates 34 one at each extremity of its top edge. From the plate 34 the hook 25 then passes up into another hole in the bracket 24, the engagement with and locking in that other hole being determined by adjustment of nut 33. That is to say the hook may be engaged by turning the nut in one direction and released by a reverse action.

As shown in Figure 3 the two sections of strips 12 are hung respectively from a lower and an upper portion of the endless chain 14.

Accordingly, as the motor 18 activates the chain 14 to move around wheel 16 in the direction of arrow A those lower and upper portions of endless chain 14 and the sections of strips 12 hung from the chain portions move respectively in the opposite directions B and B'.

Disposed beneath the floor of the doorway is an induction loop 26 which extends on either side of the door to the outside and inside of the building served by the doorway. The induction loop is electrically linked to a control box 27 which can adjust the signal level at which one or more relays 29 are activated so that an electric current can operate the motor 18 to move the strips 12 either to an open or a closed position depending on the presence or absence of a predetermined signal level.

Referring in particular to Figure 4(a) to 4(c), a vehicle 28 on the outside of the building is shown approaching the doorway 11 in Figure 4(a). As the vehicle approaches the doorway its metallic nature is detected by the induction loop 26 beneath the doorway and this loop sends an electrical signal to the control box 27. The control box includes circuitry allowing adjustment so that the motor 18 is activated to move chain 14 in the direction of arrow A only when it is clear that a vehicle requires an open passage through the door. In addition, the activation level is set and the loop is chosen so that the door remains open for the minimum possible time.Then as the vehicle 28 moves through the doorway into the building and passes over the induction loop its influence on the loop decreases and at an appropriate point the electrical signal fed from the loop to the control box diminishes below the level at which the door is activated to an open position. The control box via relay(s) 29 then reverses the direction of motor 18 and the strips 12 are moved back to the closed position as shown in Figure 4(c).

In a typical arrangement as described above the induction loop may be arranged so that there is an average open time of about 5 seconds, and so that the doors are fully opened within about 1 to 2 seconds, e.g. about 1.5 seconds, from contact between the vehicle and the loop. This may be achieved with a loop which extends from about 3' 6" to about 4' both to the outside and to the inside of the doorway. Typically the strips 12 are arranged so as to provide an open passage of about 4 ft., thus allowing for average size loads.

Claims (21)

Claims

1. A flexible strip door, which door comprises at least one first section comprising a plurality of flexible strips hanging from a fixed support, at least one second section comprising at least one flexible strip hanging from a movable support, means to move the or each second section away from the centre of the door and towards one side, if necessary at least partially to overlap a corresponding first section, thereby providing an open passage through the doorway, a detector positioned to detect an object requiring an open passage through the doorway and means operable by the detector to activate the means to move the or each second section.

2. A door according to claim 1, wherein there are two first sections arranged on either side of a single central second section.

3. A door according to claim 1, wherein there are two first sections arranged on either side of two side-by-side central second sections, each second section being movable to overlap an adjacent first section.

4. A door according to any one of the preceding claims, wherein each second section comprises a plurality of flexible strips.

5. A door according to any one of the preceding claims, wherein the flexible strips comprise a plastics material.

6. A door according to claim 5, wherein the flexible strips comprise polyvinylchloride.

7. A door according to any one of the preceding claims, wherein the strips of the or each first section are hung on hooks from a supporting element fixed to the door lintel.

8. A door according to any one of the preceding claims, wherein the means to move the or each second section includes a conveyor moving in a continuous path.

9. A door according to claim 8, wherein the continuous path is from adjacent one edge of the door to adjacent the other edge and back again.

10. A door according to claim 8, wherein there are two second sections one of which is hung from a continuous conveyor so that one second section is movable by a portion of the conveyor which moves from the centre of the door to one edge thereof and the other second section which is movable by another portion of the conveyor which moves from the centre of the door to the other edge thereof.

11. A door according to any one of claims 8 to 10, wherein the conveyor comprises an endless chain.

12. A door according to any one of the preceding claims, wherein the conveyor is driven by an electric motor disposed to one side of the door lintel.

13. A door according to any one of the preceding claims, wherein the detector produces an electrical signal and the means to activate the means to move the or each second section comprising at least one electrically operable switching device.

14. A door according to any one of the preceding claims, wherein the detector is an induction loop disposed beneath the door and extending outwards to the front and rear of the door in a plane substantially normal to the door plane.

15. A door according to any one of claims 1 to 13, wherein the detector is a detector of electromagnetic radiation, and including means to generate a beam of electromagnetic radiation at the front and rear of the door whereby the presence or absence of an object to the front and rear of the door may be detected by the presence or absence of reflected or interrupted radiation.

16. A door according to claim 15, wherein the generator and detector are respectively a transmitter and a receiver of microwaves.

17. A door according to any one of claims 1 to 13, wherein the detector is an infra red detector.

1 8. A door according to any one of the preceding claims, wherein control means are provided to allow adjustment of the level of detector signal whereby the means operable by the detector to activate the means to move the or each second section can be set to an active function above a minimum threshold.

19. A door according to any one of the preceding claims, wherein the strips overlap.

20. A door according to claim 19, wherein the, strips overlap by from about 50% to about 100%.

21. A flexible strip door substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.