GB2517704B

GB2517704B - Damper for an airflow duct having a closing mechanism

Info

Publication number: GB2517704B
Application number: GB1315269.9A
Authority: GB
Inventors: Mcarthur Andrew; Perrin Richard
Original assignee: SPECIALIST VENTILATION SERVICES Ltd; Kent Tooling and Components Ltd
Current assignee: SPECIALIST VENTILATION SERVICES Ltd; Kent Tooling and Components Ltd
Priority date: 2013-08-28
Filing date: 2013-08-28
Publication date: 2019-07-03
Anticipated expiration: 2033-08-28
Also published as: EP3039352A1; GB2517704A; WO2015028777A1; GB201315269D0

Description

DAMPER FOR AN AIRFLOW DUCT HAVING A CLOSING MECHANISM

The present invention relates generally to the field of dampers for use in air flow ducts, and in particular, to fire dampers having an improved seal and lockability when in a closed position.

INTRODUCTION

Airflow ducts and ductwork, such as pipes, tubes, canals or conduits, are generally used in heating, ventilation and air conditioning (HVAC) to deliver and remove air from one location to another. The provided airflow may be utilized to, inter alia, supply air, return air and/or exhaust air.

Currently available duct systems come in many shapes and sizes and may be made of a variety of materials. For example, galvanized mild steel is often used in fabricating ductwork and can be considered to be a common standard for airflow duct systems.

Typically, HVAC systems comprise many other components, such as smoke and/or fire dampers, which are usually installed where the duct passes through a firewall or fire curtain. Smoke and/or fire dampers may be operated using manually operable mechanical mechanisms (e.g. fire dampers) or motors (e.g. smoke dampers). The mechanical mechanisms or motors are often referred to as actuators. A probe may be installed within the "run” (i.e. ductwork) of the duct that is coupled to the actuator in order to detect, for example, smoke that has been extracted from a room, or which is being supplied from an Air Handling Unit (AHU) or from anywhere else within the "run”. For example, upon detecting a predetermined concentration of smoke within the duct, the actuator is automatically triggered to close the smoke and/or fire damper shut. When the situation is under control, the duct may be re-opened manually.

Such fire dampers are usually not triggered by any electrical powered system, i.e. an electrical motor, to minimize the risk of system failure due to loss of power, and may be mounted in either horizontal or vertical configurations. Vertically mounted fire dampers may be gravity operated while horizontal fire dampers may be spring powered.

In either case, a fire damper typically comprises a fusible link that will fail at a specified temperature, therefore allowing the damper to be actuated under gravity or spring power and effectively close the duct so as to "starve” the fire of the required oxygen. In particular, a commonly used type of damper usually consists of a flap pivotably mounted within a duct, and which can move between an open position, allowing airflow through the duct, and a closed position, preventing airflow through the duct. However, when in the closed position, the "seal” between the flap and the duct wall is only provided by the flap edge abutting a flange potion or rim of the duct. A typical example of a known fire damper is shown in Figure 1, the damper is installed within a duct wall 2, which is circular in cross-section. A continuous circular rim 4 having an inwardly extending flange 6 is riveted to the duct wall 2 at several positions around the rim by sealed rivets (not shown). The rim 4 has a step 8, to form a wall portion 10 which is spaced from the duct wall 2. The rim serves to provide a mounting and a stable mating surface for a flap or blade 12, and also strengthens the duct to maintain the duct shape in the region of the flap 12 to provide improved operation.

The flap or blade 12 is pivotably mounted on the rim 4 and is shown in full outline in its closed position, and in dotted outline in the open position. As seen in Figure 1, the blade is stepped or joggled at a diameter region 12a so that the halves of the flap 12b, 12c occupy planes to either side of and parallel to the plane of the flange 6, when the flap is in the closed position.

However, because the blade is stepped through the rim at its diameter region, the blade will not be able to sealingly engage with the rim in that region, causing an insufficient seal between the rim and the flap edge and allowing at least part of the smoke to move past the flap. Also, because the flap is urged into the closed position via biasing means, such as a torsion spring, a sufficient pressure difference between the upstream end on one side of the damper and the downstream end on the other side of the damper may overcome the biasing force of the spring, further opening the flap and increasing the leak.

Accordingly, it is an object of the present invention to provide a damper, such as a fire damper, adapted to provide an improved seal, as well as an improved closing mechanism suitable to prevent any accidental opening of the flap when in its closed position.

SUMMARY OF THE INVENTION

Preferred embodiments of the invention seek to overcome one or more of the above disadvantages of the prior art.

According present invention, there is provided a damper for an airflow duct, comprising: a tubular housing, having a first end and a second end, forming a passageway through said housing along a longitudinal first axis (z), said first end further comprising a flange extending radially inward from said first end; an actuator, operatively coupled to a damper element, the actuator comprising an axle, the axle arranged coaxially with and pivotably movable about a central second axis (x) within said passageway that is perpendicular to said first axis (z), the damper element, being linearly moveable along said first axis (z) between a closed position, where said damper element sealingly engages with said flange, and an intermediate position, where said damper element is spaced apart from and closingly oriented within said passageway in a plane substantially parallel to said flange, and wherein said damper element is pivotably movable about the central second axis (x), between said intermediate position and an open position, where said damper element is openly oriented so as to permit fluid flow through said passageway; at least one first biasing member, adapted to urge said damper element towards the intermediate position, when between said closed and intermediate positions, and at least one second biasing member, adapted to urge said damper element towards the intermediate position, when between said open and intermediate positions.

Preferably, the damper element is lockable in said first position.

This provides the advantage that the edge portion of the blade (damper element) can be pressed against a flange or rim of the housing from one side, leaving no gap between the contacting surfaces. In particular, by moving the pivot axis of the blade away from the flange/rim of the housing, the blade can now be pivoted within the passageway without interfering with the inwardly extending flange/rim of the housing. Therefore, mating contact surfaces of the blade and the rim can be pressed against each other from a single direction, providing a uniform contact surface between the rim and the blade, maximising the sealing capability of the engaging surfaces. In addition, because the blade is pressed against the rim surface from only one direction (i.e. linearly from one side, rather than pivotally pressing on opposite sides of the rim, as is the case in the prior art), the blade can be locked effectively in its closed position by any blocking means (e.g. a wedged cam).

Advantageously, the actuator may further comprise a handle portion, adapted to rotate said axle about said second axis (x).

Even more advantageously, the damper element is coupled to said actuator via a cam mechanism. Preferably, the cam mechanism comprises at least one cam, mounted to said axle, and at least one corresponding cam follower, mounted to said damper element and operatively engaged with said at least one cam. Preferably, the cam mechanism comprises at least one second cam and corresponding at least one second cam follower, identical to and arranged symmetrically to said at least one first cam and corresponding at least one first cam follower with respect to a centre axis of said housing. Even more preferably, the at least one first cam follower is adapted to limit the extent of movement of said at least one first cam. Even more preferably, the at least one second cam follower is adapted to limit the extent of movement of said at least one second cam.

Advantageously, the flange comprises a contact surface oriented towards said passageway and inclined at a predetermined angle with respect to a plane described by the flange. Preferably, the damper element comprises a contact surface inclined at the predetermined angle with respect to the plane described by the flange, and adapted to matingly engage with the contact surface of the flange.

Advantageously, the contact surface of the flange sealingly engages with contact surface of the damper element.

Advantageously, the contact surface of the flange and/or contact surface of the damper element comprises a seal.

Advantageously, the damper further comprises a stopper member, adapted to prevent pivotal movement of said damper element past said intermediate position when moving from the open position back towards said intermediate position. Preferably, the stopper member is mounted inside said passageway.

Advantageously, the damper element is a blade.

Advantageously, the damper further comprises a retention member, coupled to said damper element, and a fixation member, coupled to said housing and adapted to engage with said retention member so as to retain said damper element in a predetermined open position between said intermediate position and said open position.

Even more advantageously, the tubular housing is of substantially circular cross section. Preferably the damper is a fire or smoke damper.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the present invention will now be described, by way of example only and not in any limitative sense, with reference to the accompanying drawings, in which:

Figure 1 shows a schematic cross section of a side view of a known damper mechanism having a pivotable damper blade that sealingly engages with opposite contact surfaces of the housing rim when in its closed position;

Figure 2 shows a schematic close-up side view of the cam mechanism moving the blade from the intermediate position (a) towards the rim into the closed position (b);

Figure 3 shows another schematic close-up side view of the cam in engagement with its cam follower moving the blade from (a) the intermediate position towards (b) the closed, locked position;

Figure 4 shows a detailed schematic, partially cross-sectioned side view of the damper, including actuator (partial pivot axis), cam follower (in-situ and exploded), blade, housing and cam (exploded side-view), (a) when in the closed position, and (b) when in the intermediate, spaced apart position;

Figure 5 shows schematic top view of some parts of the damper mechanism, including the housing, connecting base plate for the blade and one cam follower (cross section in situ, exploded and viewed from the side (A));

Figure 6 shows a side view of the base plate including oval opening for the pivot axis, allowing linear movement of the pivot axis;

Figure 7 shows a close-up, part cross-section side view of the blade contacting surface profile;

Figure 8 shows a cross-section side view of the blade in engagement with the rim/flange of the housing;

Figure 9 shows a close-up part of the blade contacting surface and the mating rim contacting surface, as well as part of the cam follower pivot axis spacer, which limits the linear movement of the blade;

Figure 10 shows a simplified schematic of the cam mechanism of the present invention (a) when moving from a first, closed position towards an intermediate, spaced apart position, and (b) when moving from the intermediate, spaced apart position into a third, open position;

Figure 11 shows a top view of the blade with pivot axis space and schematically exploded guide plates, and

Figure 12 shows a partial side-views of a guide plate, adapted to guide the movement of the blade via attached pivot axis spacer, where (a) is guide plate without spacer, (bj shows guide plate and blade in a closed position, (cj shows guide plate and blade in theintermediate position, and (dj shows guide plate and blade in the third, open position.

DETAILED DESCRIPTION OF EMBODIMENTS

Referring now to Figures 2 to 6, cross-sectional partial views and exploded views of key parts of an embodiment of the damper of the present invention are shown to facilitate the comprehensibility of the damper mechanism. In particular, Figures 2 (a) and (bj show a side view of the damper blade 100 and base plate 102 mounted centrally onto the damper blade 100. The base plate 102 comprises two support potions 104, located on either side of the base plate 102 and aligned at 90 degrees with respect to the base plate 102. An axle 106 is transversely and pivotably mounted through respective coaxial holes 108 in the two support portions 104 and respective holes 110 in the damper housing 112 (shown in Figure 4). Two cams 114 are fixed to the axle 106 adjacent to respective support portions 104. Two cam follower members 116 are mounted onto the damper blade 100 so as to operatively engage with respective cams 114. Each of the identical cams 114 has a predetermined contact surface that is adapted to engage with the contact surface of respective cam follower member 116. In this particular embodiment, the cam body profile is shaped by at least two plane side portions angled with respect to each other. The cam surface of this particular embodiment is of substantial hexagonal shape, that is eccentrically mounted onto the pivot axle 106, so as to allow the plane side portions to engage with respective contact surfaces of the cam follower members 116 and the base plate 102. A retention member 200 is mounted onto the axle 106 so as to be engaged by a clamp (not shown), allowing the damper blade to be fixed in a predetermined position/angle with respect to the direction of a passageway through the housing (i.e. along a longitudinal axis (z) of the tubular housing). This particular damper blade retention mechanism has been disclosed previously and is not described in any further detail.

Furthermore, a first biasing element (not shown), such as a helical spring, is operatively mounted to the axle 106 so as to urge the damper blade 100 and attached base plate 102 toward the axle 106. Preferably, the biasing element is located at a central portion of the axle 106. A second biasing element (not shown), such as a helical spring, is operatively mounted to a portion of the axle 106 outside the housing 112 so as to urge the damper plate 100 towards a closed position with respect to the housing 112.

Two spacer elements 118 are located at radially opposite edges of the damper blade 100 between the damper blade 100 and the axle 106. The spacer elements 118 may be mounted onto the damper blade 100, but may also be an integral part of the damper blade 100. The spacer elements 118 are operatively engaged with respective guide plates 120 mounted to the interior wall of the housing 112 in coaxial alignment with the holes 108,110 and the axle 106. The guide plates 120 are adapted to limit the movement of the spacer elements 118 and consequently the movement of the damper blade 100. A stopper member (not shown) is attached to the interior wall of the housing 112 so as to only allow the damper blade 100 to pivot in one direction.

Referring now to Figures 7 to 9, a close-up side view of the damper blade profile is shown, as well as, a side view of the contact surface 122 of the damper blade 100 and the contact surface 124 of the housing flange or rim 126. Both contacting surfaces 122,124 are oriented towards the passageway (i.e. towards a direction that is opposite the flow through the passageway) and inclined at a predetermined angle (e.g. 60 degrees) with respect to the plane described by the flange 126. Therefore, when the damper blade 100 is in its closed position, any pressure from the passageway increases the contact pressure of the contact surfaces 122 and 124.

The function of the damper blade mechanism is now described with reference to Figures 10,11 and 12.

When the damper blade 100 is in its closed position (dashed lines in Fig. 10 (a)), cams 114 are positioned so as to lockingly engage with the upper surface of the damper blade 100, i.e. the plane side portion of the cams engage with the upper surface of the damper blade 100 pressing the contacting surfaces 122, 124 of the damper blade 100 and the housing flange 126 towards each other. The damper blade 100 is locked in this position by the cams 114, and it is not possible to open the damper blade 100 by pushing onto the damper blade 100 from the outside.

In order to open the damper blade 100, axle 106 is pivoted about its longitudinal pivot axis, for example, manually via a handle portion connected to the axle 106, or automatically via a motor operatively mounted to the axle 106. The pivot movement of the axle 106 pivots the cams 114 out of engagement with the damper blade 100 and into engagement with the contacting surface of respective cam follower members 116. Further pivoting of the axle/cams 106, 114 the cam follower members 116 and attached damper blade 100 rise until the spacer elements 118 (see Figs. 11, 12) contact the axle 106 preventing any further linear movement (rising) of the damper blade 100. At this point the force provided by the cams 114 acting on the contact surface of the cam follower members 116 provides a turning moment about the axle 106 pivoting the damper blade 100 about the longitudinal pivot axis of the axle 106 and moving the damper blade 100 in an open position.

Linearly moving the damper blade 100 towards the pivoting axis of the axle 106 and out of engagement with the contact surface 124 of the housing flange 126, decreases the diameter of the turning circle 128 of the damper blade 100 so that it can pivot through the opening defined by the housing flange 126.

Figure 11 shows disassembled parts of the damper blade 100, comprising spacer elements 118, and the guide plates 120. Figure 12 shows step-by-step movement of the spacer elements 118 when moving the damper blade 100 out of engagement with the contact surface 124 of the housing flange 126 and into a fully open position (e.g. in line with the direction of the flow path of the passageway of the housing 112). During the initial rise of the damper blade 100 out of engagement with the contact surface of the housing flange 126 (Fig. 12 (b)), the spacer element 118 moves up until it contacts the axle 106 (Fig. 12 (c)) where the cam 114 and cam follower member 116 "lock” and pivot the damper blade 100 into its open position. The guide plate 120 defines and limits the movement of the spacer elements 118, i.e. it blocks any further movement past the 'fully-open’ position of the damper blade 100 (Fig. 12 (d)).

It will be appreciated by persons skilled in the art that the above embodiment has been described by way of example only and not in any limitative sense, and that various alterations and modifications are possible without departing from the scope of the invention as defined by the appended claims. For example, in a preferred embodiment of the present invention, the damper is fully made of metal, however, alternatively, other materials, such as specific seals or coatings, may be used to improve the functionality and performance of the damper mechanism.

Claims

1. A damper for an airflow duct, comprising: a tubular housing, having a first end and a second end, forming a passageway through said housing along a longitudinal first axis (z), said first end further comprising a flange extending radially inward from said first end; an actuator, operatively coupled to a damper element, the actuator comprising an axle, the axle arranged coaxially with and pivotably movable about a central second axis (x) within said passageway that is perpendicular to said first axis (z), the damper element being linearly moveable along said first axis (z) between a closed position, where said damper element sealingly engages with said flange, and an intermediate position, where said damper element is spaced apart from and closingly oriented within said passageway in a plane substantially parallel to said flange, and wherein said damper element is pivotably movable about the central second axis (x), between said intermediate position and an open position, where said damper element is openly oriented so as to permit fluid flow through said passageway; at least one first biasing member, adapted to urge said damper element towards the intermediate position, when between said closed and intermediate positions, and at least one second biasing member, adapted to urge said damper element towards the intermediate position, when between said open and intermediate positions.

2. A damper according to claim 1, wherein said damper element is lockable in said first position.

3. A damper according to any one of the preceding claims, wherein said actuator further comprises a handle portion, adapted to rotate said axle about said second axis (Y).

4. A damper according to any one of the preceding claims, wherein said damper element is coupled to said actuator via a cam mechanism.

5. A damper according to claim 4, wherein said cam mechanism comprises at least one cam, mounted to said axle, and at least one corresponding cam follower, mounted to said damper element and operatively engaged with said at least one cam.

6. A damper according to claim 5, wherein said cam mechanism comprises at least one second cam and corresponding at least one second cam follower, identical to and arranged symmetrically to said at least one first cam and corresponding at least one first cam follower with respect to a centre axis of said housing.

7. A damper according to claim 5 or claim 6, wherein said at least one first cam follower is adapted to limit the extent of movement of said at least one first cam.

8. A damper according to claim 6 or claim 7 when dependent on claim 6, wherein said at least one second cam follower is adapted to limit the extent of movement of said at least one second cam.

9. A damper according to any one of the preceding claims, wherein said flange comprises a contact surface oriented towards said passageway and inclined at a predetermined angle with respect to a plane described by the flange.

10. A damper according to claim 9, wherein said damper element comprises a contact surface inclined at the predetermined angle with respect to the plane described by the flange and adapted to matingly engage with the contact surface of the flange.

11. A damper according to claim 10, wherein the contact surface of the flange sealingly engages with the contact surface of the damper element.

12. A damper according to any one of claims 10 and 11, wherein the contact surface of the flange and/or contact surface of the damper element comprises a seal.

13. A damper according to any one of the preceding claims, further comprising a stopper member, adapted to prevent pivotal movement of said damper element past said intermediate position when moving from said open position back towards said intermediate position.

14. A damper according to claim 13, wherein said stopper member is mounted inside said passageway.

15. A damper according to any one of the preceding claims, wherein said damper element is a blade.

16. A damper according to any one of the preceding claims, further comprising a retention member, coupled to said damper element, and a fixation member, coupled to said housing and adapted to engage with said retention member so as to retain said damper element in a predetermined open position between said intermediate position and said open position.

17. A damper according to any one of the preceding claims, wherein said tubular housing is of substantially circular cross section.

18. A damper according to any one of the preceding claims, wherein said damper is a fire or smoke damper.