BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a cross-sectional end view a unit ventilator with its damper at a full return air position.
FIG. 2 is a cross-sectional end view similar to FIG. 1 but showing the damper at its full outside air position.
FIG. 3 is a cross-sectional end view similar to FIGS. 1 and 2 but showing the damper at an intermediate position.
FIG. 4 is a perspective view of the damper assembly used in the unit ventilator of FIGS. 1-3.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIGS. 1-3, a unit ventilator 10 includes a heat exchanger 12 (e.g., evaporator, condenser, water chilled coil, water heated coil, electric heater, etc.) and a blower 14 for discharging a current of supply air 16a into a comfort zone 18, such as a room or other area within a building 20. Blower 14 and heat exchanger 12 are contained within an enclosure 22 that defines a return air inlet 24 for receiving used return air 16b from comfort zone 18, an outside air inlet 28 for receiving fresh outside air 16c, and a supply air outlet 30 for releasing supply air 16a into comfort zone 18.
Referring further to FIG. 4, ventilator 10 also includes a damper assembly 32 with a damper shaft 34 that can pivot about an axis 36 (longitudinal centerline of shaft 34) to determine the supply air's mixture of outside air 16c and return air 16b. A drive unit 38, such as an electric motor or some other rotational actuator, includes a drive shaft 40 directly coupled to damper shaft 34 such that damper shaft 34 and drive shaft 40 are inline with axis 36. The direct inline coupling of shafts 34 and 40 eliminates the use of expensive or problematic linkages. Drive unit 38 can be controlled to drive the pivotal motion of damper assembly 32 according to some desired control scheme known to those of ordinary skill in the art.
When drive unit 38 drives damper assembly 32 to a full return air position, as shown in FIG. 1, substantially all of supply air 16a is made up of return air 16b. In this position, blower 14 draws return air 16b in through return air inlet 24 and discharges the air out through supply air outlet 30. With damper assembly 32 in the full return air position, the air travels in series through return air inlet 24, an air filter 42, a blower inlet 44, a blower outlet 46, heat exchanger 12, and supply air outlet 30.
FIGS. 2 and 4 show damper assembly 32 driven to a full outside air position where substantially all of supply air 16a is from outside air 16c. In the full outside air position, blower 14 draws outside air 16c in through outside inlet 28 and discharges the air out through supply air outlet 30. With damper assembly 32 in the full outside air position, the air travels in series through outside air inlet 28, filter 42, blower inlet 44, blower outlet 46, heat exchanger 12, and supply air outlet 30.
FIG. 3 shows damper assembly 32 at an intermediate position where supply air 16a is from a mixture of outside air 16c and return air 16b. In this position, air enters enclosure 22 through both return air inlet 24 and outside air inlet 28. The two streams of air travel upward through filter 42, and a mixture of the two streams travel sequentially through blower inlet 44, blower outlet 46, heat exchanger 12, and supply air outlet 30.
To avoid the problems of previous unit ventilators, damper assembly 32 has several unique features that include, but are not limited to, 1) a single damper blade unit 48 comprising a return air damper blade 48a and an outside air damper blade 48b directly driven by inline drive unit 38, 2) a filter rack 50 that not only supports filter 42 but also provides damper assembly 32 with structural support, 3) filter rack 50 also defines a sealing surface 54 against which flexible edge seal 56a of damper blade unit 48 can seal, 4) rigid sealing edges 58 and 60 offer flexible end seals 56b of damper blade unit 48 with a solid abutting surface against which to seal, 5) a first gusset 62 and a second gusset 64 attached to damper blades 48a and 48b help create a rigid box-like structure with a concavity 66 in damper blade unit 48.
Although the actual structure of damper assembly 32 may vary, in some embodiments, damper assembly 32 comprises two main subassemblies, a stationary frame 68 and pivotal damper blade unit 48. Frame 68 comprises filter rack 50 connected to an inboard endplate 71 and an outboard endplate 70. Inboard endplate 71, which is generally a mirror image of outboard endplate 70, is shown in phantom lines in FIG. 4 to uncover other details of damper assembly 32. Filter rack 50 comprises a front frame member 72, a back frame member 74, and a plurality of cross members 76, which are of a size and quantity to accommodate one or more filters 42. The frame illustrated in FIG. 4 is designed to hold two filters 42 side-by-side. Cross members 76 have a generally L-shaped cross-section. The horizontal flange of the L-shaped members 76 can be used to help support lateral edges of filter 42. A horizontal flange of front frame member 72 and a horizontal flange of back frame member 74 can support front and rear edges of filter 42.
In this example, damper blade unit 48 comprises return air damper blade 48a and an outside air damper blade 48b. To minimize the number of parts, damper blades 48a and 48b are blanked and formed from a unitary piece of sheet metal. A central region 78 of damper blade unit 48 is affixed to damper shaft 34 using screws or some other appropriate attachment means. Endplates 70 and 71 each include a journal bearing 80 for supporting damper shaft 34 so that damper blade unit 48 can pivot relative to frame 68.
For rigidity along the length of damper blade unit 48, damper blades 48a and 48b each include an integrally formed rib 82 that runs generally parallel to axis 36, and blades 48a and 48b lie at an angle to each other, i.e., blades 48a and 48b are not coplanar. Thus, an outside air damper blade tip 84 and a return air damper blade tip 86 define an imaginary plane that is offset to axis 36. To add rigidity across the damper blade unit's width (as measured perpendicular to axis 36 from return air damper blade tip 84 to an outside damper blade tip 86), gussets 62 and 64 are attached to damper blades 48a and 48b. As a result, damper blades 48a and 48b, gussets 62 and 64, and ribs 82 provides damper blade unit 48 with a box-like structure that is rigid in directions both parallel and perpendicular to axis 36.
To help separate the return and outside air, a stationary splitter plate 88 attached to endplates 70 and 71 and further attached to one or more cross-members 76 extends into concavity 66. A flexible seal 90 attached to the lower edge of splitter member 88 seals against central region 78 of damper blade unit 48. Splitter plate 88 has notches 92 to accommodate gussets 62 and 64. A dividing member 94 underneath shaft 34 and attached to endplates 70 and 71 also helps separate the return air and outside air. A flexible seal 96 attached to dividing member 94 help seal any gap between shaft 34 and dividing member 94.
Another important feature of damper assembly 32 is its ability to provide a solid tight seal at both its full return air position of FIG. 1 and its full outside air position of FIG. 2, and yet drive unit 38 only needs to overcome minimal frictional sealing drag when damper assembly 48 is at some intermediate position, such as the position shown in FIG. 3. To accomplish this, end seals 56b and edge seals 56a have little or no contact with frame 68 when damper assembly 32 is at some intermediate position (FIG. 3); however, the sealing forces increase dramatically when damper assembly 32 reaches the full return air position (FIG. 1) or the full outside air position (FIG. 2). At the full return air position (FIG. 1), edge seal 56a firmly abuts a lower surface of back frame member 74, and end seals 56b firmly abut sealing edges 58 that protrude from endplates 70 and 71. Likewise, at the full outside air position (FIG. 2), edge seal 56a firmly abuts a lower surface of front frame member 72, and end seals 56b firmly abut sealing edges 60 that protrude from endplates 70 and 71. Although the structure of seals 56a and 56b may vary, in some embodiments seals 56a and 56b are made of a flexible neoprene-like material.
To help prevent frost and condensation from collecting on outside damper blade 48b, in some embodiments a layer of thermal insulation 98 overlies damper blade 48b.
In a currently preferred embodiment, enclosure 22 includes an access panel 100 for periodically replacing filter 42.
Although the invention is described with respect to a preferred embodiment, modifications thereto will be apparent to those of ordinary skill in the art. Therefore, the scope of the invention is to be determined by reference to the following claims.
Patent Application
20070290057
