NZ247311A - Flow damper adjustment mechanism: screw or threaded rod operates butterfly valve - Google Patents

Description

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F.Z^E.^.l-CKV.Ofcs) AQj... .B.<S»VL2jA LUA^SO Publication Date: ?.7..AQY..J995 P.O. Journal No: ... I3.3& PATENTS FORM NO. 5 Fee No. 1 & 4: $340.00 PATENTS ACT 1953 COMPLETE SPECIFICATION ' FLOW DAMPER ADJUSTMENT MECHANISM We Holyoake Industries Limited, a New Zealand company of Waokauri Place, Mangere, Auckland, New Zealand hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed to be particularly described in and by the following statement: - f,T C - 'MAR 1993" 1 „ 24 7 3 1 1 FLOW DAMPER ADJUSTMENT MECHANISM TECHNICAL FIELD This invention relates to a flow damper adjustment mechanism.

For convenience only, the present invention will be described with reference to 5 a flow damper adjustment mechanism for an airconditioning diffuser for which the invention may be particularly suitable. However it is to be understood that it is not to be limited as such. Moreover, because the invention may have many other applications, prior art and possible applications of the invention discussed below, are given by way of example 10 only.

BACKGROUND ART Diffusers for airconditioning systems are generally fitted with a flow damper so that after installation, the damper may be adjusted to give the required volume flow from the diffuser. The damper generally comprises one or more 15 damper vanes pivotally mounted at the inlet to the diffuser which restrict the flow to the diffuser depending on their orientation. In a typical twin vane configuration, similar vanes of a suitable size so as to each fit across approximately half of the duct are positioned in the duct with their adjacent edges pivotally mounted relative to the duct wall.

Orientation of the vanes in the duct is generally achieved by a linkage mechanism with a screw or clamping plate for adjustment. In a typical adjustment mechanism the vanes are linked with link arms so as to pivot together, and a screw is used to adjust the position of a link arm connection 24 7 3 1 point thereby causing the opposite vanes to move together to either open or close the duct passage.

These types of adjustment mechanism however generally involve several components, and are complicated in design adding to the cost of the diffuser. 5 Since setting of the diffuser damper need only be effected once or twice in the life of the system there is thus a need for a simpler lower cost mechanism for damper adjustment.

DISCLOSURE OF THE INVENTION It is an object of the preseiit invention to address the foregoing problems or at 10 least to provide the public with a useful choice.

Further aspects and advantages of the present invention will become apparent from the ensuing description which is given by way of example only.

According to one aspect of the present invention there is provided an adjustment mechanism for a duct flow damper, said flow damper having two 15 damper vanes contained in said duct with adjacent edge portions pivotally mounted with respect to said duct, said adjustment mechanism including; an operating member, means for mounting said operating member so as to optionally retain said operating member in a fixed position relative to said duct, and engagement surfaces provided on adjacent portions of said edge portions, said engagement surfaces being adapted for engagement with surfaces of said operating member over a predetermined angle of rotation of said engagement surfaces about respective axes of said pivotal mounts when said operating 247311 • . 5 « Q 20 member is positioned therebetween with an axis substantially perpendicular to said pivotal axis of said edges.

According to another aspect of the present invention there is provided a method of adjusting the orientation of vanes of a flow damper having two vanes with adjacent edge portions pivotally mounted in a duct, said edge portions having engagement surfaces provided on adjacent portions thereof, said engagement surfaces being adapted for engagement with surfaces of an operating member over a predetermined angle of rotation of said engagement surfaces about respective axes of said pivotal mounts, the method comprising the steps of; engaging the surfaces of a rigid operating member between said engagement surfaces with a longitudinal axis of said operating member substantially perpendicular to said pivotal axis of said edge portions, and moving said operating member in an axial direction thereof so that the surfaces of said operating member in engagement with said engagement surfaces urge said adjacent edge portions so as to pivot about their respective pivotal mountings, thereby changing the orientation of said vanes in said duct.

According to another aspect of the present invention there is provided a method of adjusting the orientation of vanes of a flow damper having two vanes with adjacent edge portions pivotally mounted in a duct, said edge portions having engagement surfaces provided on adjacent portions thereof, said engagement surfaces being adapted for engagement with threads of a threaded rod over a predetermined angle of rotation of said engagement surfaces about respective axes of said pivotal mounts, the method comprising the steps of; 1 iQCr fill 24731 1 engaging the threads of a threaded rod between said engagement surfaces with a longitudinal axis of said threaded rod substantially perpendicular to a pivotal axis of said edge portions, and retaining said rod from axial movement while rotating said rod relative to said engagement surfaces so that the thread of said rod in engagement with said engagement surfaces urges said adjacent edge portions so as to pivot about their respective pivotal mountings, thereby changing the orientation of said vanes in said duct.

By providing an operating member in engagement with the adjacent surfaces of the edge portions of the damper vanes as described above, movement of the vanes may be achieved by simply moving the operating member relative to the surfaces. The apparatus thus provides a low cost mechanism whereby the orientation of the vanes on the duct may be adjusted.

The operating member may be any suitable member which is able to exert a force on the edge portions of the damper vanes so that the damper vanes may be urged to rotate about their pivotal axis. For example this may comprise a flexible or rigid elongate member which is gripped between the opposing adjacent engagement surfaces of the damper vanes. The surface of the operating member which engages with the engagement surface of the edge portions of the vanes may be smooth and rely simply on friction to enable an urging force to be applied to the engagement surface, or may be formed with a rough surface, or a ribbed surface such as with a gear rack. Similarly the engagement surface of the vane edge portion may be smooth, rough or ribbed, as required or desired. 24 7 3 1 1 Alternatively the operating member may comprise a member such as a bolt or screw formed with an inclined rib or thread which bears on the engagement surface of the vane edge with sufficient engagement so that rotation of the operating member causes an urging force to move the surface in the direction of advance of the thread. By having a relatively soft engagement surface the thread may cut its own groove in the surface so as to provide sufficient grip.

Alternatively grooves may be formed in the engaging surfaces which mate with the inclined ridges or thread.

Since operation of the vanes is generally only required at installation the only major requirement is that the nature of the contacting surfaces be such that they are low in manufacture cost and remain engaged once set in position.

In order that the engagement surfaces may engage with the surface of the operating member over the desired amount of rotation of the vanes about their pivotal mounting, the engagement surface may preferably be formed with a radius of curvature centred on the pivotal axis of the pivotal mount. In the case of a ribbed surface formed to engage a flat ribbed surface or threaded surface on the operating member, the engaging surfaces of the ribs would preferably lie on this radius of curvature. Since the vane is only required to be rotated a limited amount in the duct, the engaging surface need only comprise a small sector of the edge portion of the vane.

In order for the operating member to effectively urge the edge portion of the vane to rotate about its pivotal mounting, the operating member should preferably be orientated so as to operate in a direction perpendicular to the pivotal axis of the edge portion. However the range of inclination to the pivotal axis may vary, and in the above description, the term substantially 247311 perpendicular is taken to cover a range wherein the movement of the operating member would be effective in causing rotation of the vane over a useful range.

The operating member may be either flexible or rigid. In the case of a flexible member, the arrangement may be such that flow over the vanes ensures a tension is applied to the member. Alternatively, a return spring may be provided to maintain tension. The flexible member may be attached to one of the vanes so that engaging contact is only required with an engagement surface of the other vane.

Any suitable means may be used for mounting and optionally retaining the operating member in a fixed position relative to the duct so that the damper vanes may be held in a set position. For example this may comprise a slot formed on a portion of the operating member with a clamp screw whereby the member may be clamped to a portion of the duct with the screw in different positions in the slot.

In the case of a threaded rod operating member it is generally envisaged that the rod would be optionally retained from rotation once rotated a required amount by the frictional contact between the thread surfaces and the engagement surfaces, so that only restriction to axial movement would be required. This may be achieved by having a mounting for the threaded rod comprising a retainer whereby the rod may be rotatably retained with respect to the duct while being restrained from axial movement. For example the rod may be mounted by means of a hollow elongate support member supported in the duct, the support member having an end blank at one end thereof with an aperture formed therein of sufficient diameter to allow the threaded rod to pass therethrough while retaining the head of threaded rod, the threaded rod 24 7 being axially retained in one direction by the end blank, and in an opposite direction by a clamp member such as a spring clip attached to the shank of the rod.

In a preferred embodiment the damper vanes are made so as to each fit 5 across approximately half of the duct with their adjacent edge portions substantially centrally disposed across the duct and lying in substantially the same plane as a cross sectional plane of the duct. However the invention is not limited to this arrangement, and the edge portions of the vanes may be aligned in different planes as required and desired, the essential requirement 10 being that the engagement surfaces of the edge portions may be engaged with engaging surfaces of the operating member during movement of the operating member relative thereto. For example, the adjacent edge portions may lie in a plane perpendicular to the cross sectional plane of the duct with the operating member aligned with the cross sectional plane.

The engagement surfaces may be formed as separate elements which may be fitted to the edge portions of the vanes, or may be formed integral with the edge portions. Having separate elements enables them to be made of material different to that used for the edge portions and more suitable for engagement with the operating member. Integral forming may however be preferable 20 from a manufacturing point of view, and it is generally envisioned that the material of the edge portions would also be suitable for the engaging surfaces.

In a preferred embodiment of the present invention, each of the damper vanes may be made from a sheet material with edges of the sheet wrapped around a cylindrical rod member to form the edge portion. Pivotal mounting of the edge 25 portion may be achieved by means of shafts formed on opposite ends of the rod and inserted into apertures in the duct wall. With this construction the § J cylindrical rod provides a convenient means for ensuring that the engagement surfaces of the edge portions have a suitable curvature for engagement with the surface of the operating member.

Further aspects of the present invention will become apparent from the 5 ensuing description which is given by way of example only and with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1: is a schematic perspective view of a flow damper adjustment mechanism according to a first embodiment of the present 10 invention, and Figure 2; is a sectional view of the flow damper adjustment mechanism similar to that of Fig. 1 installed in a ceiling diffuser.

BEST MODE FOR CARRYING OUT THE INVENTION As shown in Figs. 1 and 2, a flow damper to which the mechanism of the 15 present invention is applicable is generally indicated by arrow 1.

The flow damper 1 comprises two damper vanes 2,2 having respective adjacent edge portions 3,3 substantially centrally disposed across a circular duct 4. As shown more clearly in Fig. 2, the vanes 2,2 are each made from a sheet plastic with one edge wrapped over a plastic rod 5 and bonded to the rod 20 5. The ends of the rod 5 are formed with shafts 6 protruding therefrom. The vanes 2 are pivotally mounted in the duct 4 by pivotal mounts generally indicated by arrow 7 which comprise the shafts 6 fitted into bearing holes 8,8 formed in diametrically opposite sides walls of the duct 4, and spaced a predetermined distance apart. 247311 In operation the vanes 2,2 are oriented in the duct 4 about their respective pivotal mounts 7 so as to provide a required degree of damping of the flow through the duct. The mechanism of the present invention whereby the vanes 2,2 are orientated in the duct 4 comprises a threaded rod in the form of a 5 screw 9, which is engaged with thread 10 between opposite engagement surfaces 11,11 of the adjacent edge portions 3,3 of the vanes 2,2. The screw 9 is retained at its head end by means of a hollow central support 12 which also acts as a support for other components of a ceiling diffuser generally indicated by arrow 13 in Fig. 2. The upper end of the support 12 is covered 10 with a blank 14 drilled with ia hole to allow the shaft of the screw 9 to pass freely therethrough while retaining the head of the screw 9. At the time of installation, a spring clip 15 is fitted onto the shaft of the screw 9 after insertion through the hole in the blank 14 so that the screw 9 is restrained from axial movement both in an upwards and downwards direction, while 15 being free to rotate. Since the threads 10 of the screw 9 are engagingly fitted between the opposite engagement surfaces 11,11, rotation of the screw 9 results in the engaged screw threads 10 exerting an upwards or downwards force on the opposite edge portions 3,3 of the vane 2,2, thereby tending to turn the vanes 2,2 about their pivotal mountings 7.

The orientation of the vanes 2,2 in the duct 4 may thus be adjusted by rotation of the screw 9 in the appropriate direction. Due to the pitch of the thread 10 and the frictional engagement with the engagement surfaces 11,11, the vanes 2,2 are securely held in the set position without the need for locking rotation of the screw 9.

The present embodiment is aimed at situations where adjustment of the damper is only occasionally required. Hence special provision for 247311 strengthening or toughening the engagement surfaces 11,11 of the vane edge portions 3,3 is not required since the sheet plastic used for the vanes 2,2 is generally of sufficient strength to act as a thread bearing surface. However in situations where frequent adjustment is required this region may be strengthened, or a toughened insert may be fitted.

Furthermore, in the present embodiment a screw is used for the threaded rod, as this is low in cost and is found to be adequate for general applications. However any suitable threaded rod member may be used depending on requirements.

A flow damper adjustment mechanism such as that described above has several advantages over conventional mechanisms as follows, however it should be appreciated that all such advantages may not be realized on all embodiments of the invention, and the following list is given by way of example only as being indicative of potential advantages of the present invention. Furthermore, it is not intended that the advantages of the present invention be restricted to those of the list which follows 1. Inserting an operating member between the pivotally mounted adjacent edge portions of the diffuser vanes provides a simple low cost method for positionally orientating the vanes in a duct. 2. By designing the mechanism to operate with a standard screw for the operating member, the cost of the mechanism may be kept to a minimum. Furthermore, since the threads of the screw may cut their own grooves in the engaging surfaces, preparation of the engaging surfaces is not required. 24731 3. The use of a cylindrical rod member to form the edge portions of the vanes, provides a simple method of forming a suitably curved engaging surface so that the vanes may pivot smoothly over a wide range of orientation. 4. The use of a simple spring clamp washer to retain the screw in the support simplifies assembly and disassembly and minimises costs.

. The design is suitable for use with diffusers such as ceiling diffusers which generally have a central hollow support providing access to the adjusting screw.

Aspects of the present invention have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the scope thereof as defined in the appended claims.

Claims (12)

WHAT WE CLAIM IS:

1. An adjustable flow damper mounted in a duct, said flow damper having two damper vanes contained in said duct with adjacent edge portions pivotally mounted with respect to said duct, said adjustable flow damper including; a rotable rigid operating member, a support means mounting said operating member in position relative to said duct between the pivotal vanes with an axis of rotation substantially perpendicular to the pivot axes of said edge portions, and the vanes having engagement surfaces provided on adjacent portions of said edge portions, said engagement surfaces being such that rotation of said operating member causes rotation of said damper vanes, said rotation of said operating member also acting to cut grooves in said engagement surfaces.

2. An adjustable flow damper as claimed in claim 1, wherein said operating member applies force to said engagement surfaces of said edge portions when the operating member is rotated in either direction.

3. An adjustable flow damper, as claimed in claim 2, wherein said operating member comprises a threaded rod, and wherein said support means includes a retaining means whereby said rod is rotatably mounted with respect to said duct while being restrained from axial movement.

4. An adjustable flow damper as claimed in any one of claims 1 to 3, wherein said adjacent edge portions are substantially centrally disposed across said duct and lie in substantially the same plane as a cross sectional plane of said duct. 4 7 3 1

5. An adjustable flow damper as claimed in any one of claims 1 to 4, wherein said engagement surfaces are formed integral with said edge portions.

6. An adjustable flow damper as claimed in claim 3, or any of claims 4 or 5 5 (when appended to claim 3), wherein said grooves when cut in said engagement surfaces mate with thread ridges of said threaded rod.

7. An adjustable flow damper as claimed in any one of claims 4 to 7 (when appended to claim 3), wherein said support means comprises a hollow elongate support member co-axially supported in said duct, said support 10 member having an end blank at one end thereof with an aperture formed therein of sufficient diameter to allow said rod to pass therethrough while retaining a head of said rod, said rod thereby being axially retained in one direction by said end blank, and in an opposite direction by a clamp member attached to the shaft of said rod adjacent the support member at the said one 15 end.

8. An adjustable flow damper as claimed in any one of claims 1 to 7, wherein each of said damper vanes comprises a sheet material with an edge thereof wrapped around a cylindrical rod member forming part of the pivot mounts so as to form said adjacent edge portion. 20

9. A method of adjusting the orientation of vanes of a flow damper having two vanes with adjacent edge portions pivotally mounted in a duct, said edge portions having engagement surfaces provided on adjacent portions thereof, and a support means mounting an operating member in position relative to said duct between said pivotal vanes, said method comprising the steps of; -14- engaging surfaces of the rigid operating member between said engagement surfaces with a longitudinal axis of rotation of said operating member substantially perpendicular to said pivotal axes of said edge portions, and rotating said operating member and moving it in an axial direction thereof so that the surfaces of said operating member cut grooves in said engagement surfaces and urge said adjacent edge portions to move and pivot the vanes about their respective pivotal mountings, thereby changing the orientation of said vanes in said duct.

10. A method of adjusting the orientation of vanes of a flow damper having two vanes with adjacent edge portions pivotally mounted in a duct, said edge portions having engagement surfaces provided on adjacent portions thereof, said engagement surfaces being such that, upon rotation of a threaded rod, engagement by threads of the threaded rod cuts grooves in said engagement surfaces, said method comprising the steps of; engaging the threads of the threaded rod between said engagement surfaces with a longitudinal axis of said threaded rod substantially perpendicular to the pivotal axes of said edge portions, and mounting the threaded rod in position relative to the duct in such a way that it is retained from axial movement yet enables rotation of said rod relative to said engagement surfaces so that the thread of said rod in engagement with said engagement surfaces urges said adjacent edge portions to move so as to pivot the vanes about their respective pivotal mountings, thereby changing the orientation of said vanes in said duct.

11. An adjustable flow damper substantially as described herein with reference to the accompanying drawings. 247

12. A method of adjusting the vanes of a flow damper substantially described herein with reference to the accompanying drawings. HOLYOAKE INDUSTRIES LIMITED by its Attorneys JAMES & WELLS -16-