Method and apparatus for passively controlling airflow

Abstract

A system and method for providing a substantially constant volume exhaust or ventilation air terminal system is shown for controlling exhaust and/or return airflow rates in a system having a central fan or ventilator. The system and method permits zone-by-zone or area-by-area airflow regulation or control in non-demand areas in response to a demand or call for ventilation in demand areas. In one embodiment, the system employs at least one constant airflow controller or regulator situated in a damper. In one embodiment, a terminal houses a plurality of sub-ducts each having an airflow regulator. At least one of the sub-ducts has a damper. When the damper is open, a maximum airflow through the terminal is a sum of maximum airflow permitted by the regulators.

What is claimed is: 
     
         1 . A zone control terminal for use in an air distribution system, said zone control terminal comprising:
 a housing having an entry opening for receiving airflow and an exit opening;   a damper hingeably coupled to said housing and situated between said entry opening and said exit opening;   a motor for driving said damper between an open position and a closed position;   at least one first airflow regulator that is not situated in series with said damper;   at least one second airflow regulator situated in series with said damper;   wherein said at least one first airflow regulator controls or permits a predetermined minimum amount of airflow through said housing when said damper is in said closed position and said at least one second airflow regulator cooperating with said at least one first airflow regulator to control or permit a predetermined maximum amount of airflow through said housing when said damper is in said open position, said predetermined maximum amount of airflow through said zone control terminal being a sum of a maximum airflow rate of said at least one first airflow regulator and a maximum airflow rate of said at least one second airflow regulator.   
     
     
         2 . The zone control terminal as recited in  claim 1  wherein said at least one first airflow regulator is a constant airflow regulator over a varying range of pressure. 
     
     
         3 . The zone control terminal as recited in  claim 1  wherein said at least one second airflow regulator is a constant airflow regulator over a varying range of pressure. 
     
     
         4 . The zone control terminal as recited in  claim 2  wherein said at least one second airflow regulator is also a constant airflow regulator over a varying range of pressure. 
     
     
         5 . The zone control terminal as recited in  claim 1  wherein said at least one second airflow regulator is situated in a duct, said damper being operatively associated with said duct so that when said damper is in said closed position, no airflow passes through said at least one second airflow regulator. 
     
     
         6 . The zone control terminal as recited in  claim 1  wherein when said damper is in said closed position, said airflow passes through said at least one first airflow regulator and does not pass through said at least one second airflow regulator. 
     
     
         7 . The zone control terminal as recited in  claim 1  wherein when said damper is in said open position, said airflow passes through said at least one first airflow regulator and also passes through said at least one second airflow regulator to permit said predetermined maximum amount of airflow through said zone control terminal. 
     
     
         8 . The zone control terminal as recited in  claim 1  wherein said damper and said at least one second airflow regulator are situated in a common sub-duct or duct member. 
     
     
         9 . The zone control terminal as recited in  claim 1  wherein said at least one first airflow regulator is situated in a sub-duct or duct extension in said housing independent of said damper and said at least one second airflow regulator. 
     
     
         10 . The zone control terminal as recited in  claim 8  wherein said housing comprises a wall having a first aperture and a second aperture, said at least one first airflow regulator being adapted to regulate airflow through said first aperture and said at least one second airflow regulator and said damper being adapted to regulate airflow through said second aperture. 
     
     
         11 . The zone control terminal as recited in  claim 10  wherein a first sub-duct or duct member is coupled to said wall and in communication with said first aperture and at least one first airflow regulator is situated in said first sub-duct or duct member. 
     
     
         12 . The zone control terminal as recited in  claim 10  wherein a second sub-duct or duct member is coupled to said wall and in communication with said second aperture and having at least one of said damper or said at least one first airflow regulator situated in said second sub-duct or duct member. 
     
     
         13 . The zone control terminal as recited in  claim 12  wherein both said damper and said at least one second airflow regulator are situated in said second sub-duct or duct member. 
     
     
         14 . The zone control terminal as recited in  claim 12  wherein said first sub-duct or duct member is situated adjacent said second sub-duct or duct member is said housing. 
     
     
         15 . The zone control terminal as recited in  claim 1  wherein said zone control terminal further comprises at least one third airflow regulator situated in said damper. 
     
     
         16 . The zone control terminal as recited in  claim 1  wherein a maximum airflow rate of said at least one first airflow regulator is different than a maximum airflow rate of said at least one second airflow regulator. 
     
     
         17 . The zone control terminal as recited in  claim 16  wherein a maximum airflow rate of said at least one first airflow regulator is less than a maximum airflow rate of said at least one second airflow regulator. 
     
     
         18 . The zone control terminal as recited in  claim 1  wherein each of said at least one first airflow regulator and said at least one second airflow regulator comprises a single constant airflow regulator. 
     
     
         19 . The zone control terminal as recited in  claim 1  wherein said at least one first airflow regulator permits a minimum amount of airflow from an area in a structure. 
     
     
         20 . The zone control terminal as recited in  claim 19  wherein said minimum amount of airflow is at least 10 CFM. 
     
     
         21 . The zone control terminal as recited in  claim 1  wherein a motor control signal for energizing said motor is generated by at least one switch. 
     
     
         22 . The zone control terminal as recited in  claim 21  wherein said switch responds to at least one of a humidity sensor, manual control, timed mechanism, occupancy, or other indicators of presence. 
     
     
         23 . The zone control terminal as recited in  claim 1  wherein said damper actuates a damper switch in response to said motor driving said damper to said open position. 
     
     
         24 . The zone control terminal as recited in  claim 1  wherein said damper further comprises a pivot arm coupled to said motor and a spring mounted on said pivot arm for biasing said damper to said closed position. 
     
     
         25 . The zone control terminal as recited in  claim 1  wherein said housing defines a terminal duct, said zone control terminal further comprising:
 a first sub-duct, duct member or duct extension situated in said terminal duct; 
 a second sub-duct, duct member or duct extension situated in said terminal duct; 
 said first sub-duct, duct member or duct extension having said at least one first airflow regulator therein for regulating airflow through said first sub-duct, duct member or duct extension; 
 said second sub-duct, duct member or duct extension having said at least one second airflow regulator therein for regulating airflow though said second sub-duct, duct member or duct extension; 
 said damper being operatively coupled to or associated with said second sub-duct, duct member or duct extension to cause no airflow or airflow that is regulated by said at least one second airflow regulator to flow therethrough. 
 
     
     
         26 . The zone control terminal as recited in  claim 1  wherein both of said at least one first airflow regulator is located in a first sub-duct, duct member or duct extension and said at least one second airflow regulator is located in a second sub-duct, duct member or duct extension, each of said first and second sub-duct, duct member or duct extensions being located inside said housing so that said at least one first and second airflow regulators can control airflow through said housing. 
     
     
         27 . The zone control terminal as recited in  claim 1  wherein at least one said at least one first airflow regulator or said at least one second airflow regulator is located in a sub-duct, duct member or duct extension mounted inside said housing. 
     
     
         28 . The zone control terminal as recited in  claim 27  wherein said housing is generally rectangular and said sub-duct, duct member or duct extension is generally cylindrical. 
     
     
         29 . The zone control terminal as recited in  claim 28  wherein said housing has a wall defining a plurality of apertures, said zone control terminal comprising a plurality of sub-ducts, duct members or duct extensions associated with each of said plurality of apertures. 
     
     
         30 . The zone control terminal as recited in  claim 29 , wherein said plurality of sub-ducts, duct members or duct extensions comprises two. 
     
     
         31 . The zone control terminal as recited in  claim 29 , wherein said plurality of sub-ducts, duct members or duct extensions comprises more than two. 
     
     
         32 . A zone control exhaust terminal comprising:
 a housing having a first opening coupled to a duct and a second opening associated with an area to be ventilated, said housing directing airflow from said inlet to said outlet along a predetermined path;   a damper hingeably coupled to said housing for controlling airflow between said area and a fan or ventilator;   a motor for driving said damper from a closed position at which said damper becomes situated in said predetermined path and an open position at which said damper permits airflow along said predetermined path in response to a motor control signal; and   an airflow regulator situated in said predetermined path, said airflow regulator regulating airflow along said predetermined path at a first rate when said damper is in said closed position.   
     
     
         33 . The zone control exhaust terminal as recited in  claim 32  wherein said airflow regulator is dynamic constant airflow regulator over a varying range of pressure. 
     
     
         34 . The zone control exhaust terminal as recited in  claim 32  wherein said airflow regulator is integral with said damper. 
     
     
         35 . The zone control exhaust terminal as recited in  claim 34  wherein said damper is generally planar and pivots about a pivot axis, said airflow regulator being coupled to said damper such that it pivots about said pivot axis when said damper is actuated between said closed position and said open position. 
     
     
         36 . The zone control exhaust terminal as recited in  claim 34  wherein said damper is generally planar and lies in a first plane when said damper is in said closed position, said airflow regulator being coupled to said damper such that it also lies in said first plane and permits airflow through said damper at said first rate. 
     
     
         37 . The zone control ventilation system as recited in  claim 36  wherein said airflow regulator is a passively controlled constant airflow regulator over a varying pressure ranging between 0.20 and 0.80 inches W.G. 
     
     
         38 . The zone control exhaust terminal as recited in  claim 32  wherein said airflow regulator is situated in said duct. 
     
     
         39 . The zone control exhaust terminal as recited in  claim 32  wherein said airflow regulator is situated in said predetermined path when said damper is in said closed position and removed from said predetermined path when said motor actuates said damper to said open position. 
     
     
         40 . The zone control exhaust terminal as recited in  claim 34  wherein a second airflow regulator is situated in said duct. 
     
     
         41 . The zone control exhaust terminal as recited in  claim 32  wherein said airflow regulator permits a minimum amount of airflow from said area. 
     
     
         42 . The zone control exhaust terminal as recited in  claim 41  wherein said minimum amount of airflow is at least 10 CFM. 
     
     
         43 . The zone control exhaust terminal as recited in  claim 40  wherein said airflow regulator permits a minimum amount of airflow from said area through said duct and said second airflow regulator permits a maximum amount of airflow from said area. 
     
     
         44 . The zone control exhaust terminal as recited in  claim 43  wherein said minimum amount of airflow is at least 10 CFM and said maximum amount of airflow is less than 400 CFM. 
     
     
         45 . The zone control exhaust terminal as recited in  claim 32  wherein said motor control signal is generated by at least one of a switch. 
     
     
         46 . The zone control exhaust terminal as recited in  claim 45  wherein said switch responds to at least one of a humidity sensor, manual control, timed mechanism, occupancy, or other indicators of presence. 
     
     
         47 . The zone control exhaust terminal as recited in  claim 32  wherein said system further comprises a damper switch coupled to a remote fan for causing airflow in said duct, said damper switch being actuated when said damper is moved to said open position. 
     
     
         48 . The zone control exhaust terminal as recited in  claim 47  wherein said damper actuates said damper switch in response to said motor driving said damper to said open position. 
     
     
         49 . The zone control exhaust terminal as recited in  claim 32  wherein said damper further comprises a pivot arm coupled to said motor and a spring mounted on said pivot arm for biasing said damper to said closed position. 
     
     
         50 . The zone control exhaust terminal as recited in  claim 32  wherein said housing is dimensioned so that it can be mounted between joists. 
     
     
         51 . The zone control exhaust terminal as recited in  claim 32  wherein said damper, motor and air regulator may be detachably secured to said housing for maintenance without disconnecting said housing from said duct. 
     
     
         52 . The zone control exhaust terminal as recited in  claim 32  wherein said terminal further comprises a duct extension coupled to said housing in fluid communication with said first aperture;
 said constant airflow regulator being situated in said duct extension. 
 
     
     
         53 . The zone control exhaust terminal as recited in  claim 32  wherein said terminal further comprises:
 a duct extension coupled to said housing in fluid communication with said first aperture; and 
 a second constant airflow regulator situated in said duct extension. 
 
     
     
         54 . The zone control exhaust terminal as recited in  claim 52  wherein said terminal further comprises:
 a fan switch mounted for generating a fan signal when said damper is actuated to said open position. 
 
     
     
         55 . The zone control exhaust terminal as recited in  claim 52  wherein said terminal further comprises:
 a fan switch mounted on said support; 
 said fan switch being actuated by said damper when said damper is actuated to said open position.