U.S. patent application number 11/330278 was filed with the patent office on 2007-07-12 for control scheme for a roof vent fan assembly.
This patent application is currently assigned to Fan-Tastic Vent. Invention is credited to Stephen A. Milks.
Application Number | 20070160481 11/330278 |
Document ID | / |
Family ID | 38232893 |
Filed Date | 2007-07-12 |
United States Patent
Application |
20070160481 |
Kind Code |
A1 |
Milks; Stephen A. |
July 12, 2007 |
Control scheme for a roof vent fan assembly
Abstract
A method is provided for controlling a roof vent fan assembly
having a fan motor operably coupled to a fan. The method comprises:
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.
Inventors: |
Milks; Stephen A.; (Lapeer,
MI) |
Correspondence
Address: |
HARNESS, DICKEY & PIERCE, P.L.C.
P.O. BOX 828
BLOOMFIELD HILLS
MI
48303
US
|
Assignee: |
Fan-Tastic Vent
|
Family ID: |
38232893 |
Appl. No.: |
11/330278 |
Filed: |
January 11, 2006 |
Current U.S.
Class: |
417/44.11 ;
417/53 |
Current CPC
Class: |
F04D 27/008
20130101 |
Class at
Publication: |
417/044.11 ;
417/053 |
International
Class: |
F04B 49/06 20060101
F04B049/06 |
Claims
1. A method for controlling a roof vent fan assembly having a fan
motor operably coupled to a fan, comprising: monitoring current of
a control signal driving the fan motor; monitoring a voltage of a
power source providing the control signal for the fan motor;
determining a wattage associated with the fan motor based on the
current and the voltage; detecting a jam condition of the fan based
on the wattage associated with the fan motor; and controlling
operation of the fan motor upon detecting the jam condition.
2. The method of claim 1 further comprises detecting a jam
condition of the fan when the wattage exceeds a threshold
value.
3. The method of claim 1 further comprises detecting a jam
condition of the fan when the wattage is below a minimum value.
4. The method of claim 1 wherein said controlling comprises
stopping the operation of the fan motor and subsequently restarting
operation of the fan motor.
5. The method of claim 4 wherein said controlling comprises
stopping the operation of the fan motor for a predetermined time
period and subsequently restarting the fan motor at an increased
speed after the predetermined time period has expired.
6. The method of claim 5 further comprises repeating said
monitoring current, said monitoring a voltage, determining a
wattage, and said controlling operation of the fan until a jam
condition is no longer detected.
7. The method of claim 5 further comprises: repeating said
monitoring current, said monitoring a voltage, said determining a
wattage, and said controlling operation of the fan a selectable
number of times; and wherein if a jam condition is detected each
time of the selectable number of times, commanding the fan motor
off.
8. The method of claim 6 further comprises determining the time
period based on a number of occurrences a jam condition is
detected.
9. The method of claim 1 further comprises, commanding a
notification signal upon detecting the jam condition, wherein the
notification signal illuminates an indicator light.
10. The method of claim 1 further comprises, commanding a
notification signal upon detecting the jam condition, wherein the
notification signal activates an audio warning device.
11. A method of controlling a roof vent fan assembly having a fan
motor operably coupled to a fan, comprising: 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.
12. The method of claim 11 further comprises monitoring current of
a control signal driving the fan motor and detecting a jam
condition of the fan based on the current.
13. The method of claim 11 further comprises monitoring voltage of
a power source providing a control signal driving the fan motor and
detecting a jam condition of the fan based on the current.
14. The method of claim 11 further comprises: monitoring current of
a control signal driving the fan motor; monitoring voltage of a
power source providing the control signal for the fan motor;
determining a wattage associated with the fan motor based on the
current and the voltage; and detecting a jam condition of the fan
based on the wattage associated with the fan motor.
15. The method of claim 11 further comprises restarting operation
of the fan motor at a fan speed higher than a fan speed at which
the fan was being operated when the jam condition occurred.
16. The method of claim 15 further comprises repeating said
stopping and said restarting until a jam is not detected.
17. The method of claim 15 further comprises repeating said
stopping and said restarting for a selectable number of times, and
if each time of the selectable number of times a jam condition is
detected, turning the fan motor off.
18. The method of claim 17 further comprises turning the fan motor
back on if a fan on signal is received from a wall controller and a
jam is not detected.
19. The method of claim 11 further comprises commanding a
notification signal upon detecting the jam condition, wherein the
notification signal illuminates an indicator light.
20. The method of claim 11 further comprises commanding a
notification signal upon detecting the jam condition, wherein the
notification signal activates an audio warning device.
Description
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.
[0020] In one aspect of this disclosure, the roof vent fan control
system 30 is operable to detect a jam condition of the fan
assembly. When there is a jam condition, the fan blades as well as
the drive shaft of the fan motor will stop rotating. This in turn
causes a spike in the motor current which can be sensed by the fan
controller. In addition, there will be an increase in the amount of
power drawn by the fan motor, thereby leading to a decrease in
voltage output by the power source. This change in the power source
may also be monitored by the fan controller. Based on changes in
these parameters, the fan controller can detect a jam condition of
the fan blade and control the operation of the same
accordingly.
[0021] FIGS. 3 and 4 illustrate exemplary control schemes for a
roof vent fan assembly 10. Referring to FIG. 3, the fan controller
monitors the wattage associated with the fan motor as indicated at
100. When the wattage falls outside of a predetermined range, a jam
condition is inferred. In an exemplary embodiment, the wattage is
determined by multiplying the fan motor current by the voltage
output of the power source. It is readily understood that other
techniques may be employed to determine the wattage associated with
the fan motor. Moreover, it is envisioned that the motor current or
power source voltage individually as well as other parameters
individually or in combination may be used to infer a jam
condition.
[0022] Upon detecting a jam condition, control increments a jam
detection counter and stores a current fan speed at 120. Control
commands the fan motor to stop at 130 for a selectable period of
time. The length of the delay period is based on the number of
times a jam has been detected as indicated by the jam detection
counter. For each time a jam condition is detected, the length of
delay period is increased. Once the delay period has elapsed at
140, control commands the fan motor to start at 150. To facilitate
jarring loose any obstruction in the fan, the fan motor is
preferably started at the next highest fan speed. Control loops
back and again processes the fan wattage at 100. If the wattage is
still outside of the predetermined range at 110, then processing
repeats in a manner as described above. When the wattage falls in
the predetermined range, control resets the jam detection counter
at 160. Thus, control continues starting and stopping the fan motor
until the jam occurrence is resolved.
[0023] In an alternative approach, the fan motor will be cycled off
and on a predetermined number of times as shown in FIG. 4. A single
iteration of the jam detection method as described above in
relation to FIG. 3 is performed at 200. If the jam detection
counter is greater than a threshold X at 210, the fan is commanded
OFF at 220. Otherwise control loops back and performs another
iteration of the jam detection method. Control will continually
perform iterations of the jam detection method until the jam
detection counter is greater than the threshold X at 210. If the
jam detection threshold is greater than the threshold X at 210,
control will continue to command the fan OFF at 220 until a fan
unit OFF command is received from the wall controller. If a fan
unit OFF command is received from the wall controller at 230,
control resets the jam detection counter at 240. The fan motor
remains off until an ON command is received from the wall
controller.
[0024] It is to be understood that only the relevant steps of the
methodology are discussed in relation to FIGS. 3 and 4, but that
other software-implemented instructions may be needed to control
and manage the overall operation of the system. Furthermore, the
disclosure is merely exemplary in nature and, thus, variations that
do not depart from the gist of the disclosure are intended to be
within the scope of the invention. Such variations are not to be
regarded as a departure from the spirit and scope of the
invention.
* * * * *