GB2146426A - Dampers for ventilation systems - Google Patents

Abstract

The damper is constructed to enable a simple removal of a damaged blade (14). A retaining member (30) at one end of the damaged blade is pivoted away from the blade so that the blade end can then be moved downwards, clear of projections (28) which engage a slot (26) in an end plate (20), fixed to the blade. Once this has been done, the blade can be shifted in a lengthwise direction so that a plate (38) at the other end of the blade is moved clear of projections (28) on its respective end support (16). A new blade can then be readily fitted by reversing the sequence of operations described above for the removal of a blade. <IMAGE>

Description

SPECIFICATION Fluid damper This invention relates to fluid dampers having blades which are rotatable about respective axes extending lengthwise of the blades in order that they may move between a position in which the blades close a passage through the damper and a fully open position in which they allow the free passage of air or other gaseous fluid through that passage. Such dampers are widely used in air ventilation systems.

However carefully such dampers are treated during installation and while being used, it is likely that a damper blade in a ventilation system incorporating a large number of dampers will become damaged. In some dampers this means that the whole damper must be replaced as no provision is made for the removal of a damaged blade and the insertion of a new blade. In other cases, however, the damper blade can be replaced, but only with great difficulty.

In still other instances, the end support or supports for the damper blade become damaged themselves during removal of the blade to be replaced so that the new blade is not held correctly or safely by the damaged blade supports.

The aim of the present invention is to enable a damper blade to be readily removed and replaced by a new blade without damage or difficulty. With this aim in view, each blade of the damper is removably supported at its ends by blade end supports with one end of each blade being provided with a retaining member which normally retains that end of the blade on its respective end support but which is movable into a release position where it allows that blade end to be removed from the said blade support.

The other end of each blade, i.e., the end not having a retaining member, is also removable from its respective end support but in a more simple fashion as it is possible to slide the blade in a lengthwise direction once the end with the retaining member has been removed from its support.

An example of a fluid damper in accordance with the invention is shown in the accompanying drawings, in which: Figure 1 is a perspective view of the damper showing its blades in a partly open position; Figure 2 is an exploded perspective view of part of the damper casing showing the manner in which one of the blades is mounted on the casing; Figure 3 is an exploded perspective view of the drive means for two of the blades; and Figures 4-6 are fragmentary perspective views illustrating the manner in which a blade end having a retaining member is attached to its respective support.

The damper shown in the drawings comprises a metal casing 10 having a through passage 12 for the flow of air or other gaseous fluid through the damper. As is customary in such dampers, the flow of air through the passage 12 is controlled by a series of aerofoil hollow blades 14 made of stainless steel or some other appropriate metal. These blades are rotatable about respective axes extending lengthwise of the blades with each blade being supported at its ends by blade end supports 16 (see Figures 2 and 4). As indicated above, the blades 14 are shown in Figure 1 in a partly open position, and it will be understood that they are movable between a fully closed position in which they block the flow of air through the passage 12 and a fully open position in which they permit the free flow of air through that passage.A rotary knob 18 is provided on the outside of the casing 10 for adjusting the position of the blades. Alternatively, arrangements can be made for positioning of the blades to be effected by power means or through remote operation.

Although such dampers are generally robust, it sometimes happens in an air ventilation system incorporating a large number of such dampers that one or more of the damper blades in a damper becomes damaged. In some installations this necessitates replacement of the entire damper, but in the case of the present invention any damaged blade can be replaced very easily and without damage to the damper itself.

To make such easy removal and replacement of a damaged blade possible, each blade 14 of the damper shown in the drawings has one end provided with a shaped plate 20 which is attached to the blade end by small projections or ears 22 which enter corresponding slots or holes 24 in the shaped plate and are then twisted so as to secure the blade and the shaped plate together. The plate 20 has a slot or groove 26 formed in it which is able to receive two projections 28 on the respective blade end support 16. Figures 4-6 illustrate the way in which the said blade end is attached to its end support 16, from which it will be seen that the blade end is first lifted towards the projections 28 on the end support 16 so that those projections enter the slot 26 in the plate 20 as shown in Figure 5.Then, once the projections 28 are resting on the bottom of the slot or groove 26, a retaining member 30 which is pivotally mounted at 32 on the shaped plate 20 is swung through an angle of 180"from the position shown in Figure 5 to the position shown in Figure 6.

A co-operating dimple and pimple 34 and 36 on the retaining member 30 and the plate 20 ensure that the retaining member snaps firmly into the closed position shown in Figure 6 so that the blade end is securely fastened - but in a removable manner - on the respective projections 28 on the end support 16.

The other end of each blade is provided with a smaller plate 38 (see Figure 2) which is similarly attached to the blade end by projections or ears 22.

Each end plate 38 has a central opening 40 which is adapted to receive the two projections 28 on its respective end support 16.

Because of the construction described above, it is a simple and straightforward operation to remove a blade from the damper. All that an engineer needs to do is to snap the retaining member 30 at one end of the damaged blade out of the position shown in Figure 6 into the position shown in Figure 5 so that the blade end can then be moved downwards, clear of the projections 28 on the blade 16, into the position illustrated in Figure 4. Once this has been done, the whole blade can be shifted in a lengthwise direction so that the plate 38 at the other end of the blade is moved clear of the projection 28 on its respective end support 16.

A new blade can be readily fitted by reversing the sequence of operations described above for the removal of a blade.

The blades of the damper move in synchronism with each other by virtue of the fact that their end supports are attached to respective gear wheels 46 which mesh with one another in a space formed between an inner part 42 of the damper casing and an outer part 44. It needs to be explained in this connection that the extreme left-hand part of Figure 2 illustrates the form of casing shown in Figure 1 while the parts 42a and 44a in Figure 2 illustrate an alternative form of casing suitable for those ventilation systems where the damper needs to be flush with the duct in which it is installed. Figure 3 shows the means by which the meshing gear wheels 46 are attached to their respective blade end supports 16 and the manner in which the inner part of the casing is rivetted to the outer part of the casing. In addition, Figure 2 shows the manner in which a drive shaft 48 is adapted to turn the gear wheels 46 so as to change the position of the blades, the said shaft 48 being arranged to pass through a frusto-conical sealing member 50 of synthetic plastics material so as to prevent leakage of air through the hole 52 through which the shaft 48 passes. The mountings 54and 54a shown in Figure 2 are alternative mountings for the shaft 48 and the control knob 18, depending on which form of casing is used.

Claims (11)

1. A fluid damper having blades which are rotatable about respective axes extending lengthwise of the blades in order that they may move between a position in which the blades close a passage through the damper and a fully open position in which they allow the free passage of air or other gaseous fluid through that passage, in which, to permit any of the damper blades to be readily removed and replaced by a new blade without damage or difficulty, each blade is removably supported at its ends by blade end supports with one end of each blade or its respective support being provided with a retaining memberwhich normally retains that end of the blade on the respective end support but which is movable into a release position where it allows that blade end to be removed from the said blade support.

2. Afluid damper according to claim 1, in which the other end of each blade, i.e. the end remote from the retaining member, is removable from its respective end support by sliding the blade in a lengthwise direction once the end where the retaining member is located has been removed from its support.

3. A fluid damper according to claim 1 or claim 2, in which each blade of the damper has one end provided with a shaped plate on which the retaining member is mounted.

4. A fluid damper according to claim 3, in which each plate is attached to its respective blade end by small projections or ears which enter corresponding slots or holes in the shaped plate and are then twisted so as to secure the blade and the shaped plate together.

5. A fluid damper according to claim 3 or claim 4, in which each plate has a slot or groove formed in it which is able to receive projecting means on the respective blade end support.

6. A fluid damper according to any one of claims 3-5, in which the retaining member is pivotally mounted on the shaped plate so as to be swung between a blade-retaining position and a bladerelease position.

7. A fluid damper according to any one of claims 3-6, in which a co-operating dimple and pimple on the retaining member and the plate ensure that the retaining member snaps firmly into the closed position.

8. A fluid damper according to any preceding claim, in which the end of each blade remote from the retainer member has a plate which is attached to the blade end by projections or ears and which has a central opening to receive projecting means on its respective end support.

9. A fluid damper according to any preceding claim, in which the blades of the damper move in synchronism with each other due to their end supports being attached to respective gear wheels which mesh with one another in a space formed between an inner part of a casing of the damper and an outer part of that casing.

10. A fluid damper according to claim 9, in which a drive shaft is provided to turn the gear wheels so as to change the position of the blades, the said shaft being arranged to pass through a frusto-conical sealing member of synthetic plastics material so as to prevent leakage of air through a hole in the damper casing through which the shaft passes.

11. A fluid damper substantially as described herein with reference to the accompanying drawings.