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Control scheme for a roof vent fan assemblyRelated Patent Categories: Pumps, Condition Responsive Control Of Pump Drive Motor, By Control Of Electric Or Magnetic Drive Motor, Responsive To Change In Electrical Operating CharacteristicControl scheme for a roof vent fan assembly description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20070160481, Control scheme for a roof vent fan assembly. Brief Patent Description - Full Patent Description - Patent Application Claims
FIELD [0001] The present invention relates to methods and systems for controlling a roof vent fan assembly. BACKGROUND [0002] Conventional applications for roof vent fans include campers, trailers, motor homes and other recreational vehicles where the enclosed space is relatively small and proper ventilation is desired to provide fresh air to the occupants of the space. Roof vent fans function to ventilate harmful fumes, pollutants, and excess heat out of the enclosed space into the atmosphere. [0003] Conventional roof vent fans include a housing adapted to be mounted to a roof. A fan assembly within the housing is driven by a fan motor. The motor may be controlled by one or more switches indicating an on/off state and a speed of the motor. A cover opens during fan operation to allow the fan access to the atmosphere. The cover closes when the fan is not operating to protect fan components as well as the enclosed space. There remains an unfilled need to automatically control conventional roof vent fans to operate more efficiently. [0004] More specifically, it can be foreseen that when the cover is open, debris may fall into the roof vent fan assembly. The debris may be large enough in size to prevent the fan from rotating thereby jamming the fan assembly. Considerable damage can be done to the motor and the fan assembly when the fan assembly is jammed. It is desirable to automatically detect a jammed fan assembly and automatically control the roof vent fan appropriately, thereby eliminating overheating as well as other potential damage. [0005] Furthermore, it can be foreseen that a power outage may occur, depriving the RV or motor home of power. If the roof vent fan assembly is operating when the power outage occurs, upon restoration of the power, a motor that controls the position of the cover may attempt to close an already closed cover thereby providing a force sufficient to damage the motor and cover components. It is desirable to automatically detect such conditions and automatically control the roof vent fan cover appropriately. SUMMARY [0006] A method is provided for controlling a roof vent fan assembly having a fan motor operably coupled to a fan. The method comprises: determining wattage associated with the fan motor; detecting a jam condition of the fan based on the wattage associated with the fan motor; and, upon detecting the jam condition, controlling operation of the fan motor. [0007] In another aspect of the disclosure, the method includes: monitoring an operating condition of the fan motor; detecting a jam condition of the fan based on the operating condition of the fan motor; and, upon detecting the jam condition, stopping operation of the fan motor and subsequently restarting operation of the fan motor. [0008] Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. BRIEF DESCRIPTION OF THE DRAWINGS [0009] FIG. 1 is a perspective view of an exemplary roof vent fan assembly; [0010] FIGS. 2A and 2B are functional block diagrams illustrating exemplary roof vent fan control systems; [0011] FIG. 3 is a flowchart illustrating a control method for detecting and controlling a fan assembly when a jam occurs; and [0012] FIG. 4 is a flowchart illustrating a second embodiment of a control method for detecting and controlling a fan assembly when a jam occurs; DETAILED DESCRIPTION [0013] The following description of various embodiments is merely exemplary in nature and is in no way intended to limit the present teachings, application, or uses. For purposes of clarity, the same reference numbers will be used in the drawings to identify the same elements. [0014] FIG. 1 is a perspective view of an exemplary roof vent fan assembly 10. The roof vent fan assembly 10 is generally comprised of a housing 12, a fan blade assembly 14, a fan motor 16 and a cover 18. The housing 12 is sized to fit over an opening in a roof and adapted to be mounted to the roof. For example, the housing 12 includes a flange which extends outwardly from a periphery of the housing, where the flange has a plurality of holes formed therein. The holes in the flange are receptive of fasteners which may be used to mount the housing to the roof. Although the roof vent fan assembly 10 is particularly suited for use in a camper, trailer, motor home, or other type of recreational vehicle, it is also suitable for ventilating other enclosures of a comparable size, including in either a vertical or horizontal application. [0015] In further detail, the housing 12 provides a cylindrical cavity for housing the fan blade assembly 14. The fan blade assembly 14 and the fan motor 16 are coupled to a mounting bracket 22 which extends over the top of the housing cavity. To provide ventilation, the cover 18 moves between an open and closed position. One or more hinges are used to couple the cover 18 to the housing 12. A cover lift mechanism 26 pivots the cover 18 up or down as well as holds the cover 18 in a desired position. The lift mechanism 26 may be manually actuated (e.g., by a handle) and/or electrically driven by a motor. Different types of lift mechanisms are contemplated by this disclosure. A screen may extend over an underside of the cavity to prevent access to the fan blade from within the enclosure. The cover 18 is configured to mechanically actuate a position switch 28 as will be further described below. [0016] FIGS. 2A and 2B are diagrams of exemplary roof vent fan control systems. The roof vent fan control system 30 is comprised of a wall controller 32, a fan controller 34, a blade assembly 14, a fan motor 16 and power source 36. The fan controller 34 is integrated into the vent fan assembly 10 described above; whereas, the wall controller 32 is configured to be mounted onto an internal wall surface of the recreational vehicle. It is also envisioned that the wall controller 32 may be detachable from the wall. The fan and wall controllers can be any known microprocessor, controller, or combination thereof known in the art. In various embodiments, the controllers include a microprocessor having read only memory (ROM), random access memory (RAM) and a central processing unit (CPU). The microprocessor may include any number of software control modules that provide the functionality for controlling a feature of roof vent fan assemblies. In various other embodiments, the controllers can be application specific integrated circuits (ASIC), electronic circuits, combinational logic circuits and/or other suitable components that provide the described functionality. [0017] In operation, a wall controller 32 receives user input 40 indicating desired fan parameters. At a minimum, the fan parameters include an on/off state of the fan and a desired fan speed. The wall controller 32 converts the user input 40 to corresponding signals and sends the signals to the fan controller 34. The fan controller 34 regulates power to the fan motor 16 from a power source 36 based on signals received from a wall controller 38. The fan motor 16 in turn drives the fan assembly 14. The fan controller 34 may send notification signals to the wall controller 32 indicating a status of the fan assembly. In an exemplary embodiment, there is a wired connection between the wall controller 32 and the fan controller 34. In an alternative embodiment, the wall controller 32 and fan controller 34 communicate via a wireless communication link using a communication protocol such Bluetooth, USB, IEEE 1394, or Wi-Fi. [0018] In FIG. 2B, the roof vent fan control system 30' further includes a motor 38 for actuating the cover 18. The fan controller 34 also controls the operation of the cover motor 38 and thus the position of the cover 18. In the event of a malfunction or loss of power, a knob 39 is preferably provided to manually adjust the position of the cover. The position switch 28 is electrically interposed between the fan controller 34 and the fan motor 16. When the cover 18 is opened, the cover position switch 28 is in a closed state, thereby allowing current to flow to the fan motor 16. When the cover 18 is in a closed position, the cover position switch is in an open state, thereby preventing current from flowing to the fan motor 16. [0019] When power is restored following a power outage, conventional control schemes will try to close the cover 18 of the roof vent fan assembly 10. In the control system 30 of the present disclosure, the fan controller 34 determines the cover position before closing the cover. If the fan controller 34 detects that the position switch 28 is in a closed state, it will drive the cover motor 38 to actuate the cover to a closed position. However, if the fan controller 34 detects that the position switch 28 is in an open state, no further action is taken, thereby preventing over tightening of the cover assembly. Continue reading about Control scheme for a roof vent fan assembly... Full patent description for Control scheme for a roof vent fan assembly Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Control scheme for a roof vent fan assembly patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. 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