GB2248682A - Apparatus for controlling air flow in ductwork - Google Patents

Abstract

Apparatus for controlling air flow in ductwork comprises a flow control valve 20 having a housing which defines two pairs of outlets 16, 16', 18, 18' and two closure flaps 36, 38 attached to a drive shaft which is arranged to be rotated by an electrical motor 34 to change the orientation of the flaps 36, 38. A further control valve (not shown) is arranged upstream of the valve 20. The two valves are controlled so that when the further valve permits only a low flow of air, the valve 20 closes the outlets 18, 18' and air passes through outlets 16, 16' only. Opening of the further valve to increase the air flow is accompanied by opening of the valve 20 to permit flow through all the outlets. <IMAGE>

Description

APPARATUS FOR CONTROLLING AIR FLOW IN DUCTWORK This invention relates to apparatus for controlling air flow in ductwork. The apparatus of the invention has particular application in relation to air-conditioning apparatus.

In air-conditioning systems it is desirable that the air discharges into a room through wall or ceiling outlets with a sufficient air velocity to maintain a satisfactory air distribution in the room. If the air velocity is too low air may fail to circulate in certain areas of the room with the result that there are "dead zones". It is desirable to provide apparatus which can ameliorate this problem, and discharge air into a room at reasonable velocity even when the air flow rate is low.

In accordance with the present invention there is provided apparatus for controlling the flow of air in ductwork, comprising a volume control valve located in ductwork, which valve controls the volume of air passing through the ductwork, and, downstream thereof, a flow control member which has a first condition in which it permits air to flow to a first outlet but not to a second outlet, and a second condition in which it permits air to flow to the second outlet, wherein the flow control member is under the control of an actuating device the operation of which is in turn dependent upon the volume of air passed by the valve.

The volume of air passing through the ductwork may be sensed, directly or inferentially. Preferably, however, the apparatus is arranged such that control means, which controls the condition of the volume control valve, is set up to enable accurate control of air volume passing through the valve, without need for sensing of the air, such means being coupled to the actuating device which controls the flow control member. Thus, when the control means is such as to permit the volume control valve to pass a small volume of air, the actuating device acts to maintain the flow control member in its first condition, whereas, once the control means is such as to permit a larger volume of air to pass, the control means acts to cause the flow control member to adopt its second condition.

Suitably, the control means comprises electrical control means.

Suitably, the actuating device is an electrical actuating device and is electrically coupled to the control means.

In other embodiment the actuating device and/or the control means and/or the coupling between them may be nonelectrical, for example pneumatic or mechanical.

Preferably, in an electrical control system, the electrical control means and/or the valve is arranged so that there is a substantially linear relationship between actuating voltage of the electrical control means and the air volume passed. The electrical actuating device which controls the flow control member suitably acts to move the flow control member from its first condition to its second condition when the said voltage is above a pre-determined voltage. Preferably, this pre-determined voltage is adjustable by the user.

Although an embodiment of the invention could be envisaged in which the flow control member, in its second condition, permits air to flow to the second outlet but not to the first outlet, with the second outlet being of larger area than the first outlet, in preferred embodiments, the flow control member, in its second condition, then permits air to flow both to the first outlet and to the second outlet.

Preferably, the actuating device which controls the flow control member comprises an electric motor. The motor may be under the control of a relay which is in a circuit of which electrical control means for the valve is a part.

The flow control member may comprise flap means. The flap means may be so located as to substantially block the ductwork leading to the second outlet, but unable to affect air flow to the first outlet, in its first condition, but be able to be turned, for example by 900, to its second condition, enabling air flow to the second outlet.

Suitably, the first and second outlets are provided in walls which are inwardly slant to the ductwork which feeds them. Thus, they may be provided in respective side walls of a tapering nose portion at the end of a run of ductwork.

The said outlets may be outlets directly into a room.

Thus, they may be associated with conventional air diffusers. Preferably, the said outlets are spaced from such outlets into a room and are connected thereto by respective ducts.

There may suitably be a pair of first outlets and a pair of second outlets, the flow control member thus permitting two or four outlets to be fed, four outlets being in use at higher rates of flow.

It will be appreciated that other embodiments could employ a third outlet, or further outlets, so that the apparatus provides three or more operating conditions. A single flow control member which permits the three or more operating conditions could be designed or a plurality of simpler flow control members, for example of the type described hereafter, could be provided.

Preferably, the volume control valve is of the type described in U.K. Patent No. 535489, having a flexible sleeve secured at each of its ends to respective annular members which are capable of relative rotation to open and close the valve. The valve has a closed condition, in which the sleeve is a substantially taut diaphragm. In the fully opened condition the valve permits the passage of a relatively broad stream of air, and it has conditions in between, in which the stream is narrower. In the context of the apparatus of the present invention, a particularly useful valve is one of the type described, in which the sleeve has a portion toward the inlet or outlet end, preferably the inlet end, formed of an elastomeric material and a portion toward the other end formed of a close-mesh textile material fixedly connected to, and coco-axial with the first-mentioned portion.

Downstream of the valve, between the valve and the flow control member, there may desirably be provided a flow-deflecting structure of the type described in our U.K. Patent Application No. 8924327.3 The invention will now be further described, by way of example, with reference to the accompanying drawings in which: Fig. 1 shows, in schematic sectional view part of airconditioning ductwork which has a flow control member; and Fig. 2 is a more detailed view of the apparatus of Fig. 1 in exploded perspective form.

The apparatus shown in Figs. 1 and 2 is located downstream of the apparatus described in our earlier U.K.

Application No. 8924327.3, namely a control valve comprising a deformable sleeve which is twisted to effect flow reduction, and a scroll-shaped flow-deflecting structure downstream thereof.

The apparatus shown in Figs. 1 and 2 comprises a box having upper and lower panels 2, 4 each of which has a rectangular portion designated as 6 in Fig. 2, and a generally triangular portion designated 8 in Fig. 2. When the box is assembled, the panels 2, 4 are spaced apart by side walls 10, 12 which conform to the shape of the sides of the panels. Air may enter the box via a frame member 14 mounted over the rectangular-shaped opening defined by panels 2, 4 and side walls 10, 12. The slant face of each side wall 10, 12 is formed with a respective front circular outlet 16, 16' and a rear outlet 18, 18'. These outlets are the only outlets provided in the box for air which has entered it through the frame member 14.

Within the box there is apparatus, designated generally as 20, for controlling the supply or air to the rear outlets 18, 18'. This apparatus comprises a pair of identical, spaced-apart plates 22, 24. Each plate is square and is mounted with its rearmost edge 26 against a respective side wall 10, 12 of the box, between the outlets 16, 18, and 16', 18' respectively. The upper and lower edges of the plates 24, 26 abut and are riveted the panels 2, 4. The front edges of the plates 24, 26 have mountings to receive a drive shaft 30 operated via an aperture 32 in the front portion of side wall 10, by a 24V AC motor 34. The drive shaft carries two flaps 36, 38, offset 1800 from each other and of size to substantially prevent the passage of air into the space between the plates 22, 24 and thence to apertures, 18, 18', when in the position shown in Figs. 1 and 2.Upper and lower flap stops 40, 42 are provided.

Operation of the motor 34 is under the control of a relay 44 which is part of a DC circuit which is used to control the upstream volume control valve. This DC circuit has provision for user selection of voltage between 0 and 10 volts and the system is arranged such that the rate of air flow through the valve is directly proportional to the DC voltage. The relay 44 switches, causing the motor 34 to rotate the drive shaft 30 through 900, once the DC voltage has reached an intermediate value, in the region of 5.5 to 6.5 volts. The exact value at which the relay switches is selectable by the user. Once the drive shaft has rotated 900 from the position shown in Figs. 1 and 2, and the flaps have been correspondingly rotated, air flow to outlets 18, 18' is permitted.

The outlets 16, 16', 18 and 18' are each connected to a separate room outlet, each having a conventional diffuser, by independent rigid or flexible ducts.

It will be appreciated that at high air flow rates the flaps will be positioned so that air passes to all four outlets. At low flow rates, however, if air were to pass to all four outlets the flow velocity in the ducts downstream of each of them would be slow, and air would be discharged into the room undesirably slowly. However, the apparatus of the present invention prevents this by effectively closing off outlets 18, 18' at low flow velocities, so permitting reasonable flow velocities through outlets 16, 16'.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims (15)

1. Apparatus for controlling the flow of air in ductwork, comprising a volume control valve located in ductwork, which valve controls the volume of air passing through the ductwork, and, downstream thereof, a flow control member which has a first condition in which it permits air to flow to a first outlet but not to a second outlet, and a second condition in which it permits air to flow to the second outlet, wherein the flow control member is under the control of an actuating device the operation of which is in turn dependent upon the volume of air passed by the valve.

2. Apparatus according to Claim 1, the apparatus being arranged such that control means, which controls the condition of the volume control valve, is set up to enable accurate control of air volume passing through valve, such means being coupled to the actuating device which controls the flow control member.

3. Apparatus according to Claim 2, the apparatus being such that when the control means is such as to permit the volume control valve to pass a small volume of air, the actuating device acts to maintain the flow control member in its first condition, whereas, once the control means is such as to permit a larger volume of air to pass, the control means acts to cause the flow control member to adopt its second condition.

4. Apparatus according to Claim 2 or Claim 3, wherein the control means comprises electrical control means.

5. Apparatus according to any of Claims 2 to 4, wherein the actuating device is an electrical actuating device and is electrically coupled to the control means.

6. Apparatus according to Claim 4 or Claim 5 when dependant upon Claim 4, wherein the electrical control means and/or the valve is arranged so that there is a substantially linear relationship between actuating voltage of the electrical control means and the air volume passed.

7. Apparatus according to Claim 6 when dependant upon Claim 4 and Claim 5, wherein the electrical actuating device acts to move the flow control member from its first condition to its second condition when the said voltage is above a predetermined voltage.

8. Apparatus according to Claim 7, wherein the predetermined voltage is adjustable by the user.

9. Apparatus according to any of the preceding Claims, wherein the flow control member, in its second condition, permits air to flow both to the first outlet and to the second outlet.

10. Apparatus according to any of the preceding Claims, wherein the actuating device which controls the flow control member comprises an electrical motor.

11. Apparatus according to any of the preceding Claims, wherein the flow control member comprises flap means.

12. Apparatus according to any of the preceding Claims, wherein there is a pair of first outlets and a pair of second outlets.

13. Apparatus according to any of the preceding Claims, wherein the volume control valve has a flexible sleeve secured at each of its ends to respective annular members which are capable of relative rotation to open and close the valve.

14. Apparatus according to any of the preceding Claims, wherein there is provided, downstream of the valve, between the valve and the flow control member, a flow deflecting structure.

15. Apparatus substantially as hereinbefore described with reference to Figures 1 and 2 of the accompanying drawings.