Fluid handling – Systems – Dividing into parallel flow paths with recombining
Reexamination Certificate
1998-07-08
2001-02-27
Hepperle, Stephen M. (Department: 3753)
Fluid handling
Systems
Dividing into parallel flow paths with recombining
C251S080000, C251S129130, C251S213000
Reexamination Certificate
active
06192931
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
Not applicable.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not applicable.
FIELD OF THE INVENTION
This invention relates to a heating and cooling system including a damper blade assembly rotatably mounted within a duct to deliver conditioned air to an enclosure, and in particular, to an arrangement for controlling the position of the damper blade assembly within the duct in accordance with the sensed temperature of the air in the enclosure.
BACKGROUND OF THE INVENTION
Many multi-room structures, such as office buildings and schools as well as residential buildings constructed during the past several years, include heating and cooling systems to deliver either relatively warm or cool conditioned air from a central source thereof to each of the enclosures or rooms in the building. Typically, one or more ducts are employed to deliver the air to each enclosure. Very often, an automatically operated damper blade assembly or similar mechanism is installed in the duct to regulate the flow of air to one or more discharge outlets located in the enclosure being conditioned by the discharge of air thereinto. The movement of the damper blade assembly may be responsive to changes in the temperature of the enclosure.
Many of these automatically operated damper blade assemblies use a spring to open the damper and an opposing electric motor and gear train assembly to close the damper and hold it in the closed position when conditioned air is not needed in the enclosure. The damper, the spring, the motor and its gear train assembly are interconnected such that as the motor closes the damper it also acts against the spring. When the motor is de-energized, the spring reacts to open the damper and in doing so rotates the motor shaft in the direction opposite its drive direction until the damper reaches an end stop defining its open position.
Certain problems, however, arise when the exact requirements of the damper blade assembly are examined. On the one hand, a relatively strong opening force for the spring is required to ensure that any friction or binding forces on the moving parts of the damper blade assembly will be overcome. On the other hand, the gear train associated with the motor is relatively fragile and will not withstand much in the way of an impact such as can be caused when a moving gear train is stopped suddenly. As a strong spring force drives the damper to an open position, it is subjecting the gear train to a substantial amount of torque. In currently used damper blade assemblies, when the damper reaches the end of its travel towards the open position and contacts an end stop, this torque is transferred to the gear train as an impact force with the result that the gear train may be damaged. Similarly, the gear train can easily be damaged if the damper blade assembly is turned by hand with too much force. This sometimes occurs during the packaging and installation of the system. While some vendors include a shock absorbing spring and add play to the assembly to reduce the chance of over-stress damage, wear of the gears continues to limit the life of the damper blade assembly. The cost of the damper blade assembly is high due to the number of parts and tolerances required.
Accordingly, it remains a challenge to construct a mechanism that can maintain the narrow balance between too powerful a spring which will damage the gear train and too weak a spring which will not be able to overcome the friction and drag that will generally increase as the damper becomes worn during its service life. In addition, it remains desirable to prevent over-stress damage to the damper blade assembly by permitting the gear train and the motor to slowly decelerate instead of causing the impact that occurs in the conventional mechanisms when they suddenly stop and the damper hits its end stop in the open position.
BRIEF SUMMARY OF THE INVENTION
The present invention advantageously provides a damper blade control employing a management arrangement which is reliant on a strong spring force for opening yet prevents the torque applied from being transferred to the gear train in a damaging manner. With such construction, an automatically operated damper blade control is provided which ensures positive opening and closing of the damper without exceedingly high manufacturing, installation and servicing costs.
It is an object of the present invention to effectively regulate the flow of conditioned air through a supply duct to a discharge outlet located in an enclosure.
It is a further object of the invention to effectively control the position of a damper blade mounted within a duct to control the conditioned air flow through the duct.
It is yet another object of the invention to produce a low cost, simplified yet reliable damper blade assembly using non-precision parts.
Still yet another object of the invention is to provide a damper blade assembly having a unique force translation arrangement which will operate equally well between the opening and closing positions of the damper.
In one aspect of the invention, a device for controlling the movement of a damper mounted in a housing between an open position and a closed position comprises a shaft rotatably secured to the damper for pivoting the damper between the open position and the closed position. A lever arm is mounted on the shaft for rotation therewith, and a spring is connected between the housing and the lever arm for normally urging the damper towards the open position. A motor is mounted on the housing and is actuable to overcome the force of the spring to move the damper to the closed position. A force translation arrangement is disposed between the motor and the lever arm for translating the driving force of the motor when the motor is energized to move the damper to the closed position, and allow gradually braking the motor due to its internal friction when the motor is de-energized and the spring returns the damper to the open position.
In yet another aspect of the invention, there is contemplated a drive system for a damper rotatably mounted on a shaft in a housing between an open position and a closed position. The housing includes a rotatable element joined to the shaft for rotation therewith, a biasing element is provided for urging the damper to the open position, and a motor is actuable to overcome the force of the biasing element to move the damper to the closed position. The improvement resides in a wind-up spool mounted on the housing in driving engagement with the motor. A flexible band extends between the spool and the rotatable element, the band being windable upon the spool when the motor is selectively actuated to move the damper to the closed position. The band is unwindable from the spool when the motor is deactivated allowing the biasing element to rotate the shaft, the damper, the rotatable element, the motor and the spool such that the damper returns to the open position. The spool and the band define an over-travel mechanism for preventing damage to the motor as the damper assumes the open position.
Still another aspect of the invention contemplates a mechanism for driving at least one damper supported on a housing for motion between an open position and a closed position. The mechanism comprises at least one rotatable shaft secured to at least one damper for pivoting the damper between the open position and the closed position. A lever arm is mounted on the at least one shaft for rotation therewith, the lever arm being equipped with a pair of stop surfaces. A pair of stops are secured to the housing, each of the stops being engageable with one of the stop surfaces so as to define the limits of travel of the damper corresponding to the open position and the closed position. A biasing device is connected between the housing and the lever arm for normally urging the at least one damper towards the open position. A spool is rotatably mounted on the housing, and a flexible band extends between the spool and the lever arm, the band being windable upon the spool. A motor
Guetersloh Timothy L.
Mulhall Barry B
Sokn Erick L.
Andrus Sceales, Starke & Sawall
Hepperle Stephen M.
Research Products Corporation
LandOfFree
Damper blade control does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Damper blade control, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Damper blade control will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2593003