Adjustable damper actuator

[0001] The invention pertains to heating and air conditioning systems. Particularly, it pertains to dampers which may be used in such systems. More particularly, the invention pertains to damper actuators.

[0002] Dampers in heating, ventilation and air condition (HVAC) systems typically control air flow in full open and full closed positions. There has been a need for a low cost damper actuator which can control air flow in an HVAC system or other systems with dampers having some variable open and closed positions.

[0003] The present invention is a low cost adjustable damper actuator that can actuate a damper to have positions that are other than fully open and fully closed. Mainly, the actuator provides the convenience of adjusting damper opening for make-up air without guess work. Such actuator would be useful for zone heating and air conditioning as well as for providing a continuous supply of make-up air at low flow rates. The actuator has stops which can be set to prevent full rotational or linear travel of the damper to be driven. Adjustable stops or other mechanisms are provided to limit damper travel in the opening direction and/or travel in the closing direction. The actuator has a mover mechanism, a damper moving mechanism connected to the mover mechanism, and a movement limiting mechanism connected to the moving mechanism.

[0014] FIG. 1 is an illustration of an adjustable direct drive damper actuator 10. Actuator 10 has an output shaft 11, which may be connected to a damper 12 shown in FIG. 2. Shaft 11 may rotate damper 12 to one of two desired adjusted positions in a vent or duct 13 in an HVAC system. Shaft 11 is coupled to shaft 23 of damper 13. These positions may be those that are other than a full open or full closed position. FIG. 2a shows damper 12 to be in a partially closed position. FIG. 2b shows damper 12 to be in a partially open position. The damper 12 of FIG. 2a and 2b is shown as a rotational device. However, and as shown in FIG. 2c, it is contemplated an actuator 10′ with one or more stops may control a damper 12′ of any suitable type, such as a rotational damper of various shapes, a laterally sliding device, and/or any other suitable shutting and opening mechanism, as desired. The damper positions shown in FIG. 2a and 2b may be referred to an adjusted partially closed position and an adjusted partially fully open position, respectively. For instance, such positions of the damper may be useful for situations calling for zone heating and air conditioning as well as providing for a continuous supply of make-up air at low flow rates.

[0015] Two adjustable positions may be attained with mechanical stops that can be adjusted. The stops can be manually set to prevent full rotational travel of shaft 11 of motor drive actuator 10. The adjustable stops are provided to limit the travel of shaft 11 and damper 12 in the opening direction and/or in the closing direction of damper 12. The adjustable feature may be obtained with the use of levers 14 and 15 which may set to limit rotation of drive shaft 11 of actuator 10. Levers 14 and 15 are accessible exterior to case 16 and case cover 17. FIG. 3 reveals actuator 10 with case cover 17 removed from case 16. Each lever 14 and 15 has a tab 18 and 19, respectively, which also may be regarded as an adjustable stop, as shown as an exploded view in FIG. 4. Tabs or stops 18 and 19 may interfere with a drive mechanism 22 of device 11 illustrated in FIG. 5. FIG. 5 is a view of internal workings of actuator 10 with case cover 17 and a motor 27 removed. As lever 14 or 15 is manually rotated, tab 18 or 19 moves thereby changing the position where actuator shaft 11 comes to a halt. Once lever 14 or 15 is set to a desired position, it may be secured or fixed to that position by a wing nut 20. By turning wing nut 20 clock-wise down tight on a threaded shaft 21 mounted firmly to case 16, or some other lever-securing mechanism, levers 14 and 15 may be secured in a non-moveable fashion relative to case 16. Adjustable stops 18 and 19 may be located internal or externally relative to case 16.

[0016] When shaft 11 of actuator 10 rotates relative to case 16, it may rotate shaft 23 and in turn damper 12 relative to vent or duct 13 provided that case 16 does not move relative to vent 13. To prevent such movement, an anti-rotation rod 24 is attached to case 16, and rod 24 may be inserted into a hole in vent or duct 13 or other like mechanism secured to vent 13.

[0017] Motor 27 has an output gear 28 that meshes with gear 25 of drive mechanism 22. Gear 28 of motor 27 turns gear 25 which is attached to shaft 11. Shaft 11 is turned by gear 25. Shaft 11 turns shaft 23 and damper 12 to a partially closed or partially open position, as approximately shown in FIGS. 2a and 2b, respectively. Motor 27 continues to move damper 12 until a tab 26 of drive mechanism hits adjustable stop 18 or 19. Tab 26 is in some form attached to drive shaft 11 so that it cannot rotate or move relative to shaft 11. When tab 26 hits stop 18 or 19, then gears 28 and 25, shafts 11 and 23, and damper 12 come to a stop or stand still.

[0018] Damper 12 may be in a partially closed or partially open position. Motor 27 may remain on or energized even though gear 28 and the rotor of motor 27 are not rotating. However, motor 27 through drive mechanism 22 and shafts 11 and 23, maintains damper 12 in the position it was driven to. In this position, shaft 11 is held by motor 27 against a return tension of a spring 29. Spring 29 has one end connected to case 16 and its other end connected to a tab 30 which is securely fastened to shaft 11. Tab 30 moves or rotates with shaft 11. Once motor 27 is turned off, deenergized or disconnected from its electrical power source, then shaft 11 returns back due to the tension of spring 29 pulling on tab 30. Tab 26 rotates with shaft 11 and hits stop 19 or 18 and shaft 11 comes to halt or stop.

[0019] Damper 12 is then in the other position depending on whether actuator 10 is installed in the power closed mode or the power open mode. That is, energized motor 27 moves damper 12 towards the closed position when actuator 10 is installed in the power close mode, and vice versa.

[0020] FIG. 6 shows the diagram for connecting motor 27 to electrical power source 31. The power required is 24 volts AC at 60 hertz with nominal current of 0.32 amperes. Operation of motor 27 may be controlled with a zone switch 32. Wires with power for motor 27 may be fed through a conduit hole 33 in case 16.

[0021] Motor 27, when energized, results in about 423 mNm (milli-Newton-meters), i.e., 60 inch-ounces, of torque to shaft 11 when spring 29 is returned to its initial start position. A typical time for motor 27 to move shaft 11 and damper 12 from one position to the other position, is about 30 seconds. To return back to the first position with motor 27 deenergized and under spring 29 return tension, takes about 10 seconds. The direction of shaft 11 is clockwise when motor 27 is energized and with device 10 being viewed from the base end.

[0022] Nominal angular rotation of shaft 11 is about 90 degrees but can be expanded to a maximum of about 105 degrees to get full opening and closing, covering 90 degrees of rotation, lower adjustment lever 15 is moved to the extreme left and upper adjustment lever 14 is moved to the extreme right.

[0023] Air flow adjustments may be made by adjusting levers 14 and 15. The following description indicates the adjustments available with actuator 10 installed in the power closed mode. If damper 12 that one is installing and adjusting is to operate in the power open mode, then the functions of upper lever 14 and lower lever 15 are reversed. When viewed on end as in FIG. 7, lower lever 15 is normally positioned to the extreme left. This position allows damper 12 to fully open 90 degrees when motor 27 is deenergized. To restrict the air flow in the open position, one may loosen but not remove wing nut 20 and move lower lever 15 to the right until a desired open position of damper 12 is reached. Then one should tighten wing nut 20 to retain this adjustment. With lower lever 15 in the extreme right position, damper 12 should open approximately 50 degrees with motor 27 deenergized.

[0024] Upper lever 14 is normally positioned to the right, as in FIG. 7, to provide complete shut off of vent 13 by damper 12 when motor 27 of actuator 10 is energized. If desired, to prevent complete closure by damper 12, one may loosen but not remove wing nut 20 and move upper lever 14 to the left until the desired position of semi-closed damper 12 is achieved. To maintain that position, one may tighten wing nut 20. With upper lever 14 in the extreme left position, damper 12 should close to approximately 40 degrees when motor 27 is energized.

[0025] If additional rotation of damper 12 is required beyond 90 degrees, an addition 15 degrees may be obtained by removing upper lever 14. To do this, one may first disconnect actuator 10 from damper 12 and remove it from vent 13. Then one may remove wing nut 20, the retaining ring and levers 14 and 15. Next one may reassemble actuator 10 without lever 14, and install it on vent 13 with shaft 11 coupled to shaft 23 of damper 12.

[0026] Much of the structure of actuator 10 may be made from zinc plated stamped out steel and anonized aluminum. Besides being of low power, actuator 10 is also fairly compact. FIGS. 8, 9 and 10 illustrate the various dimensions given below. Dimension 35 is 60 millimeters (mm)/2⅜ inches (in). Dimension 36 is 84.5 mm (3⅜ in); dimension 37 is 88 mm (3½ in); dimension 38 is 8.2 mm ( 5/16 in) in diameter; dimension 39 is 31.5 mm (1¼ in); dimension 40 is 19.3 mm (¾ in); dimension 41 is 15.8 mm (⅝ in); dimension 42 is 58.6 mm (2 5/16 in); dimension 43 is 29.3 mm (1 3/16 in); dimension 44 is 33.5 mm (1 5/16 in); dimension 45 is 6.4 mm (¼ in); and dimension 46 is 40.4 mm (1 9/16 in).

[0027] Motor 27 may be substituted with a solenoid, a fluid or vacuum driven device, or some other kind of mover mechanism. Damper 12 may be a rotational device of various shapes, a laterally sliding device or some other shutting and opening mechanism.

[0028] Although the invention has been described with respect to at least one illustrative embodiment, many variations and modifications will become apparent to those skilled in the art upon reading the present specification. It is therefore the intention that the appended claims be interpreted as broadly as possible in view of the prior art to include all such variations and modifications.