GB2207233A - Louvre ventilator smoke vents - Google Patents

Abstract

A ventilator comprises a plurality of louvre blades (1) mounted in or on a frame, the blades being movable from a closed position to an open position, and means for moving the blades from their closed position to their open position for ventilation purposes and/or in response to a fire or smoke. At least a majority of the blades each have their own individual biasing means (20) to aid the movement to the open position. The louvre blades have a circular channel (8) along one edge, acting as a journal, and a substantially semicircular peripheral portion (10) along the other edge, the journalled edge also including a curved lip (9) which, in use, fits within the peripheral portion of an adjacent blade. Biasing means (20) is a spring which may be located in the journal (8). A pneumatic cylinder (or electric motor) and cable combination is described which has a fusible link which, in the event of a fire, ensures the louvres open. <IMAGE>

Description

LOUVRE VENTILATOR This invention relates to a louvre ventilator, and in particular a louvre ventilator for installation in a building, which is designed to open upon detection of a fire within the building.

Ventilators of the type just described are known and are used in order to provide an outlet for smoke to improve the prospects of survival of persons who may be in the building when the fire occurs. In at least one known system automatic opening is effected by biassing the louvre blades via a common spring towards the open position through a fusible link which normally prevents opening occurring. In the event of a fire the temperature in the building eventually rises to the temperature at which the fusible link will part, typically a temperature around 70 C, and when melting occurs the biassing on the louvre blades cause the ventilator to open and permit smoke to escape.

The present invention concerns a new way of counterbalancing the blades of a louvre ventilator.

According to another aspect of the invention, there is provided a new design of louvre blade. According to a further aspect of the invention, there is provided a new operating mechanism for the louvre ventilator.

Embodiments of the invention are shown in the accompanying drawings, in which: Figure 1 is a side elevation of a louvre ventilator according to the invention, i.e. it shows the ventilator looking in the direction of the longitudinal axes of the individual louvre blades; Figure 2 is a plan view of one end of the ventilator shown in Figure 1, showing the operating mechanism.

Figures 3 and 4 show details of the arrangement shown in Figure 2; Figure 5 shows a further embodiment of a louvre blade; and Figure 6 shows a spring for use in the invention.

The illustrated ventilator comprises a plurality of elongate louvre blades 1. The number of louvre blades in a given ventilator varies depending on the size of the ventilator, but typically may be between seven and twenty-seven. The louvre blades together span a gap between end members 2 and 3. These members, together with side members 4 which can be seen in Figure 2, define an outer frame of the ventilator and each individual blade spans the gap between side members 4.

The new blade 1 comprises a flat main portion 5, an "upper" end 6 and a "lower" end 7. The terms "upper" and "lower" relate to the position of the blade when open; thus the "upper" end of blade 1 is the left hand end when the blade is in the closed position as seen in Fig. 1.

The lower end 7 comprises a generally circular hinge channel 8 which acts as a journal on which the blade pivots. The journal 8 is mounted in supports 8' on the side members 4. Above the journal 8, a lip 9 extends in an arc of approximately 90" (or less) towards the upper end.

At the upper end 6 of the blade there is a generally semicircular peripheral portion 10 which, in use, almost meets the lower end of the flat portion 5 of the adjacent blade and encloses the lip 9 of that blade. Preferably, a rubber sealing strip 11 is fitted just inside the edge of the semicircular portion to improve the water-tightness of the ventilator.

Rubber seals (not shown) may also be provided at the lateral ends of the blades, on side members 4.

The blade at the right hand end of the ventilator is journalled slightly differently from the other blades. As shown in Fig. 1, the lower end of the blade has a C-shaped portion which is pivotally mounted on the upper edge of end member 2 of the main frame of the ventilator. This blade has no lip 9, but a depending lip 12 extends downwardly from the flat portion 5.

Apart from the right hand blade just mentioned, the blades in the embodiment of Fig. 1 are formed of extruded aluminium and glass. The flat portion 5 is formed of a sheet of glass which is fitted, with seals, into upper and lower ends 6 and 7 which are formed of extruded aluminium. The blade may allow for 78% light transmission, for example.

At one or both ends of each blade there is a plate 17, depending in a vertical plane. The lower end of the plate 17 is connected by means of a pivot 18 to a flat bar 19 which runs along the entire side of the ventilator. In the known systems the bar 19 is connected at one end thereof to the end member 3 by a tension spring which biasses the louvre blades into an open position, counterbalancing the weight of the blades.

According to one aspect of the invention, the bar is biassed by a single common spring and also (or instead) each of the louvre blades 1 is biassed by its own spring 20 connected between the end of the blade and the side member 4.

Spring 20 can be seen clearly in Fig. 1; it comprises a torsion spring having two legs 21, 22 which are urged apart. At the end of one leg 21 is an angle which fits into a mounting 23 on side member 4 and at the end of the other leg 22 is an angle which fits into a hole 24 in the plate 17 of the blade.

Alternatively, the individual counterbalancing means of each blade may be provided by a torsion spring mounted in the rear hinge channel 8 of each blade and acting against the side member 4. Such a spring is illustrated in Fig. 6. The barrel 30 of the spring fits into the channel 8 of each blade and the hook 31 at one end of the barrel fits over the edge of that channel. The leg 32 at the other end extends downwardly from one end of the blade and acts against a portion of the side member 4.

The surprisingly simple but effective solution of biassing each blade individually to counterbalance the blade weight, rather than or as well as having a common spring, provides for a very efficient opening of the louvre ventilator.

As shown in Fig. 2, along one end of the main frame, beneath the blades, is mounted a pneumatic cylinder 25 and piston rod 26. The end of the piston rod 26 is connected to a bobbin mechanism 27 and to a fusible link 28 via wires or cables 29 and 39. The wires are wound on wheels 29', 39', seen in Fig. 3 which is a sectional view along line X-X in Fig. 2.

Bobbin 27 comprises a larger diameter pulley wheel 40 and a smaller diameter pulley wheel 41. Onto the smaller wheel 41 are wound cables 49 which run along the side members 4 of the frame and which are connected to the bar 19 or to the individual blades themselves. As the bobbin is mounted at one corner of the frame, the cable from one side must be diverted via pulleys 43, 44. Pulley 44 is seen clearly in Fig. 4 which is a view on line Y-Y in Fig. 2, showing also the bobbin 27 and the blades.

If the diameter of larger wheel 40 of the bobbin 27, on which the wire 29 from the piston is wound, is twice that of the wheel for the blade cables then there is a mechanical advantage of two for opening the blades. The cables pull evenly on the blades to overcome any twisting.

The operation of the louvre ventilator described above is a follows. In normal use the lourve blades are in the position shown in solid lines in the various drawings, so that they form a covering across the opening in which the louvre ventilator is installed.

The louvre blades are maintained in this position against the force of the springs by the air supplied to the cylinder 25. Any rain falling on the ventilator will run across the upper surface of the louvre and over the edge of the main frame to be led away through suitable pipes or gutters (not shown) If a fire occurs in the building in which the louvre ventilator is installed the resulting rise in temperature causes the fusible link 31 to part so that the piston rod 26 moves to open the louvre blades so that they become orientated in a generally vertical direction, i.e. the ventilator is open. The springs 20 aid this opening as they counterbalance the weight of the blades.

Should the air pressure supplied to the cylinder 25 fail for any reason the ventilator will also open.

When it is desired to open the ventilator for ordinary ventilation purposes this can be done by winding the bobbon.

Alternative arrangements are possible. For example, matters may be so arranged that in the absence of air pressure being supplied to the cylinder 25 the ventilator is closed by a closing spring which is stronger then the opening spring 20. In the event of a fire the fusible link parts so that louvres are acted on only by the opening springs 20, which thus cause the ventilator to open. If it is desired to open the ventilator for ordinary ventilation purposes, air pressure is supplied to the cylinder 25 so that the combined force of the piston 26 and the opening springs 20 exceeds that of the closing spring.

Another possibility is to dispense with the air cylinder altogether and use an electrical motor or a simple manual operation to drive the bobbin. Once again, the ventilator is kept normally closed by a closing spring which is stronger then the opening springs, and in the event of a fire the fusible link parts so that the louvres are acted on only by the opening springs 20 which thus cause the ventilator to open. If it is desired to open the ventilator for ordinary ventilation purposes, this can be achieved by means of the above mentioned cables.

A variety of other arrangements are possible, for example employing an electromagentic solenoid.

A further embodiment of the louvre blade will now be described. It should be understaood that the blade can fit into the ventilator just described and operate in the same way.

The blade 1 shown in Fig. 5 comprises a length of an aluminium extrusion. The blade shown in Figure 5 is similar to that of Fig. 1 in that it has the same hinge channel/journal 8, lip 9 and semicircular portion 10, but instead of the glass sheet it is formed of solid aluminium so it can be formed of a single extusion. It should be emphasised that both the blades of Fig. 1 and Fig. 5 extend across the full width of the main frame so that water is shed directly onto the roof, if desired.

Claims (7)

1. A louvre ventilator comprising a plurality of louvre blades mounted in or on a frame, the blades being movable from a closed position to an open position, and means for moving the blades from their closed position to their open position for ventilation purposes and/or in response to a fire or smoke, wherein at least a majority of the blades each have their own individual biasing means to aid the movement to the open position.

2. A ventilator according to claim 1, wherein the individual biasing means comprises a torsion spring.

3. An elongate louvre blade for use in a ventilator optionally a ventilator according to claim 1 or 2, the blade including a substantially circular channel along one edge, acting as a journal, and a substantially semi-circular peripheral portion along the other edge, the journalled edge also including a curved lip which, in use, fits within the peripheral portion of an adjacent blade.

4. A blade according to claim 3, wherein a sealing strip is mounted within the peripheral portion.

5. A blade according to claim 4, wherein a raised ledge is provided adjacent the said lip, the sealing strip of the blade, in use, resting on the ledge of the adjacent blade.

6. A ventilator according to claim 1 or 2, comprising a plurality of blades according to any of claims 3 to 5, wherein the blades overlap the width of the frame.

7. A louvre ventilator or blade, substantially as herein described and as illustrated in the accompanying drawings.