U.S. patent application number 12/058825 was filed with the patent office on 2009-10-01 for method and apparatus to prevent deflagration in dryers.
This patent application is currently assigned to WHIRLPOOL CORPORATION. Invention is credited to THOMAS P. GIELDA, ROBERT W. MEYER, DONALD M. TOMASI.
Application Number | 20090241368 12/058825 |
Document ID | / |
Family ID | 41114982 |
Filed Date | 2009-10-01 |
United States Patent
Application |
20090241368 |
Kind Code |
A1 |
GIELDA; THOMAS P. ; et
al. |
October 1, 2009 |
METHOD AND APPARATUS TO PREVENT DEFLAGRATION IN DRYERS
Abstract
An apparatus and method for detecting a fire in a household
dryer and responding thereto.
Inventors: |
GIELDA; THOMAS P.; (SAINT
JOSEPH, MI) ; MEYER; ROBERT W.; (COLOMA, MI) ;
TOMASI; DONALD M.; (STEVENSVILLE, MI) |
Correspondence
Address: |
WHIRLPOOL PATENTS COMPANY - MD 0750
500 RENAISSANCE DRIVE - SUITE 102
ST. JOSEPH
MI
49085
US
|
Assignee: |
WHIRLPOOL CORPORATION
BENTON HARBOR
MI
|
Family ID: |
41114982 |
Appl. No.: |
12/058825 |
Filed: |
March 31, 2008 |
Current U.S.
Class: |
34/544 |
Current CPC
Class: |
D06F 58/50 20200201;
D06F 58/30 20200201 |
Class at
Publication: |
34/544 |
International
Class: |
D06F 58/28 20060101
D06F058/28 |
Claims
1. A method for preventing deflagration in a household dryer
comprising a cabinet having a drying chamber, comprising:
determining the presence of carbon monoxide in the dryer that is
indicative of at least one of a fire and a potential for a fire;
and initiating a deflagration prevention cycle for the dryer in
response to the determination.
2. The method according to claim 1 wherein determining the presence
of carbon monoxide comprises determining the presence of carbon
monoxide in the cabinet.
3. The method according to claim 2 wherein the determining the
presence of carbon monoxide comprises sensing the presence of
carbon monoxide in the drum.
4. The method according to claim 2 wherein the sensing comprises
monitoring the output signal of a carbon monoxide sensor.
5. The method according to claim 1 wherein the dryer further
comprises a door that provides access to the drying chamber, and
wherein the initiating of the deflagration prevention cycle
comprises locking the door.
6. The method according to claim 5 wherein the initiating of the
deflagration prevention cycle further comprises terminating
operation of a heater in the dryer.
7. The method according to claim 6 wherein the initiating of the
deflagration prevention cycle further comprises terminating
operation of a drying fan.
8. The method according to claim 5 wherein the initiating of the
deflagration prevention cycle further comprises terminating
operation of the dryer.
9. The method according to claim 1 wherein the initiating of the
deflagration prevention cycle comprises terminating operation of a
heater in the dryer.
10. A method for preventing deflagration in a household dryer
comprising a rotatable drum located within a cabinet having a
drying chamber accessed by a door, comprising: determining the
presence of carbon monoxide in the dryer that is indicative of at
least one of a fire and a potential for a fire; and locking the
door of the dryer in a closed position.
11. The method according to claim 10 wherein the determining the
presence of carbon monoxide comprises sensing the presence of
carbon monoxide in the cabinet.
12. The method according to claim 11 wherein the sensing the
presence of carbon monoxide in the cabinet comprises sensing the
presence of carbon monoxide in the drum.
13. The method according to claim 10 wherein the determining
comprises monitoring the output signal of a carbon monoxide
sensor.
14. The method according to claim 13, further comprising
terminating operation of a heater in the dryer.
15. The method according to claim 14, further comprising
termination operation of a fan in the dryer.
16. The method according to claim 15, further comprising
terminating operation of the dryer.
17. The method according to claim 10, further comprising
terminating operation of a heater in the dryer.
18. A household dryer comprising: a cabinet defining an interior
and having a drying chamber therein; a door mounted to the cabinet
and selectively moveable between an opened and closed position for
closing access to the drying chamber; a rotatable drum located
within the cabinet; a fire detector located within the cabinet; a
door lock coupled with the door and selectively operable between a
locked and unlocked position; and a controller operably coupled
with the fire detector and the door lock to effect movement of the
door lock from the unlocked to the locked position in response to a
detection of at least one of a fire and a potential for a fire by
the fire detector.
19. The household dryer according to claim 18 wherein the fire
detector comprises a carbon monoxide sensor.
20. The household dryer according to claim 18 wherein the fire
detector comprises a smoke detector.
21. The household dryer according to claim 20 wherein the smoke
detector comprises a photoelectric detector.
22. The household dryer according to claim 18 wherein the fire
detector is located exteriorly of the drum.
23. The household dryer according to claim 18, further comprising a
heating element operably coupled with the controller, wherein the
controller terminates power to the heating element in response to a
detection of at least one of a fire and a potential for a fire by
the fire detector.
Description
BACKGROUND OF THE INVENTION
[0001] Dryers are well-known appliances for drying clothing and
other fabric items, such as towels, sheets, blankets, and the like.
Household dryers include a cabinet enclosing a horizontally
rotating drum sized to receive a load of fabric items and
accessible through an access door at the front of the cabinet. A
motor drives rotation of the drum. The motor may also drive a
blower or fan which delivers dry, heated or unheated air to the
drum for drying the clothing items. A heater is typically
positioned in an air inlet assembly upstream of the drum for
heating the air as it flows through the dryer. The blower exhausts
humid air from the drum through an exhaust outlet assembly to a
discharge location exterior of the cabinet.
[0002] Recently, it has been a trend to reduce energy consumption
and to make household dryers more "green", which has led to the
elimination of air gaps between the drum and the front and rear
walls to better seal the drum and eliminate heat loss to the
atmosphere. When the blower is off, the better sealing of the drum
provides such little flow of air into the drum that if there were
ever a fire in the drum the fire could be a smoldering fire because
there is insufficient air for full combustion. Smoldering fires
tend to generate greater amounts of carbon monoxide than a flaming
fire. The carbon monoxide may combust in response to an inrush of
air, such as when the door is opened. In addition, the carbon
monoxide may increase the pressure within the airtight dryer,
which, if great enough, may deleteriously stress the door,
increasing the likelihood of an inrush of air and a flaming
combustion.
SUMMARY OF THE INVENTION
[0003] The invention relates to an apparatus and method for
detecting a fire in a household dryer and initiating a deflagration
prevention cycle for the dryer. The presence of a fire may be
detected by determining if the level of carbon monoxide present in
the dryer is indicative of a fire.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] In the drawings:
[0005] FIG. 1 is a front perspective view of a dryer according to
one embodiment of the invention.
[0006] FIG. 2 is a schematic view of a dryer according to one
embodiment of the invention.
[0007] FIG. 3 is a schematic view of a fire detector according to a
second embodiment of the invention.
[0008] FIG. 4a is a schematic view of a second exemplary fire
detector according to one embodiment of the invention.
[0009] FIG. 4b is a schematic view of the second exemplary fire
detector when smoke is present according to one embodiment of the
invention.
[0010] FIG. 5 is a graph of signal strength as a function of time
illustrating a typical output of a photocell that represents a fire
in the dryer.
[0011] FIG. 6 is a flow chart of an exemplary method for
determining if a fire is present in the dryer of FIGS. 1-2
according to one embodiment of the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0012] Referring now to FIG. 1 an embodiment of the invention is
illustrated comprising a household dryer 10 according to one
embodiment of the invention for drying clothing and other fabric
items, such as towels, sheets, and blankets, having a cabinet 12
having an open face, a controller 38 having a user interface 14 for
controlling operation of the dryer 10, a door 16 hingedly mounted
to a front wall 20 of the cabinet 12, a rear wall 24, and a pair of
side walls 22 supporting a top wall 26.
[0013] A drum 34 disposed between opposing rear and front panels
34A and 34B forms a drying chamber 18. The drum 34 may be a
rotatable cylinder having rear and front edges that are received
within sealed channels of the rear and front panels 34A, 34B. The
front panel 34B may have an opening that aligns with the open face
of the front wall 20, although other configurations known to those
skilled in the art are also possible. The rotatable drum 34 may be
driven in a traditional manner by a motor (not shown).
[0014] The drum 34 may have a circumference larger than that of the
door 16 such that part of the front wall 20 covers a portion of the
front face of the drum 34. Thus, when the door 16 is in a closed
position it closes the face of the housing 12 but not the entire
face of the drum 34. However, the drum 34 may be considered to be
closed when the door 16 is in the closed position because the door
16 does effectively close the front face of the drum 34. The
relative size of the circumference of the door to that of the drum,
however, is not germane to the invention.
[0015] Referring to FIG. 2, the dryer 10 may also have a heater 36
and an air circulation system that typically includes a fan 37 for
forcing air heated by the heater 36 through the drying chamber 18
to dry the fabric items held therein. The fan is typically a blower
driven by the motor (not shown) that rotates the drum 34, although,
the fan may have its own motor in other embodiments of the
invention. The heater 36 may be operably coupled to the controller
38 such that the controller 38 may selectively energize the heater
36 to heat the air circulated through the drying chamber 18.
[0016] Additionally, the door 16 may include a lock, such as a
solenoid-activated lock 40 that may be selectively locked by the
controller 38. Other types of locks known to those skilled in the
art may also be used. The lock 40 may be operably coupled to the
controller 38 such that the controller 38 may selectively actuate
the lock 40.
[0017] A fire detector 50 may be provided for detecting a fire in
the dryer 10. The fire detector is illustrated as being located
inside the cabinet 12, exteriorly of the drum 34, but it may be
located elsewhere, including within the drum or external to the
cabinet. The fire detector 50 may be configured to provide a signal
to the controller 38 that is indicative of a fire or a potential
for a fire, e.g., smoke or smoldering exists, or a signal to the
controller 38 that the controller 38 can then use to determine if a
fire or potential for a fire is indicated.
[0018] The fire detector 50 may be any suitable single or
combination of devices or sensors used to detect the presence of a
fire or the potential for a fire. Several parameters may indicate
the presence or potential of a fire; these include temperature,
smoke, and carbon monoxide, as well as other parameters,
individually or combined, known to those skilled in the art. As
such, for example, a temperature sensor, a smoke detector and a
carbon monoxide detector may be used to detect the presence or
potential of a fire. When there is incomplete combustion inside the
dryer 10 large amounts of smoke will typically be present in the
cabinet 12. Such combustion will also typically produce heat.
Further, carbon monoxide may be produced in large amounts in a
smoldering fire because there is often incomplete combustion inside
the dryer 10.
[0019] While smoke and carbon monoxide may be used as indicators of
fire or potential of fire, it should be noted that smoke is not
necessarily detected by a carbon monoxide fire detector and carbon
monoxide is not necessarily detected by a smoke detector. A
suitable carbon monoxide detector may sense the level of carbon
monoxide in the cabinet 12, or more specifically in the drum 34,
and output an electrical signal to the controller 38 to indicate
the presence or likelihood of a fire. The level of carbon monoxide
that indicates that a fire may be present may be empirically
determined for each type of carbon monoxide fire detector.
Alternatively, a fire or a potential for a fire may be analytically
determined. In that case, when a trigger value level of carbon
monoxide is detected by a sensor a fire is present.
[0020] Regardless of the type of fire detector 50, when a fire or
fire potential is indicated from the output of the fire detector
50, the controller 38 may be programmed to take action to minimize
the deleterious effect of the fire. The controller 38 may lock the
door, shut off the heater 36, turn off the fan, spray water into
the drum 34 (in the case of some models of dryers, for example),
etc. These actions may be taken alone, in various combinations, or
as part of a specific operating cycle implement by the controller
38.
[0021] In the case of a smoldering fire where carbon monoxide may
lead to a deflagration attributable to the inrush of air upon the
opening of the door, the controller 38 may initiate a deflagration
prevention cycle for the dryer 10 that operates the
solenoid-activated lock 40 and locks the door 16 to the dryer 10.
The deflagration prevention cycle may also shut off the power to
the heater 36, shut off the fan, and may shut off the power to the
entire dryer 10. It should be noted that the deflagration
prevention cycle reduces the likelihood of a deflagration and may
not absolutely prevent a deflagration. In this sense, the term
prevention is used to mean both an absolute prevention as well as a
reduction in the likelihood of the deflagration occurring.
[0022] FIG. 3 illustrates one specific example of a suitable fire
detector 50. The fire detector 50 may be in the form of a
photoelectric detector that includes a light source 53 and a
photocell 55. This photoelectric detector may detect the level of
smoke in the cabinet 12 and thus detect if a fire or potential for
a fire may be present. A photoelectric detector may be one of
several types known to those skilled in the art. As illustrated in
FIG. 3, the photocell 55 measures the transmitted light from the
light source 53. The photocell 55 outputs a varying electrical
signal to the controller 38 depending on the amount of light it
receives from the light source 53. Smoke may block the transmitted
light on its way to the photocell 55. In this case, the reduction
in light reaching the photocell 55 causes a significant change in
the signal being sent to the controller 38 and in response the
controller 38 may determine that a fire is likely or present in the
dryer 10 and initiate a deflagration prevention cycle for the dryer
10.
[0023] Another exemplary photoelectric detector that uses light
intensity from back scattering to detect a fire or the potential
thereof is illustrated in FIGS. 4a-4b. In essence, light may be
scattered by smoke particles onto a photocell, initiating a
deflagration prevention cycle for the dryer. This type of fire
detector 100 may include a T-shaped chamber 110 (although other
shapes are also possible) with a light source 153 that shoots a
beam of light across the horizontal bar of the T-shaped chamber
110. A photocell 155, positioned at the bottom of the vertical base
of the T-shaped chamber 110, generates a current when exposed to
light. Under smoke-free conditions, such as those shown in FIG. 4a,
the light beam crosses the top of the T-shaped chamber 110 in an
uninterrupted straight line, not striking the photocell 155
positioned at a right angle below the beam. When smoke occurs, such
as shown in FIG. 4b, the smoke particles scatter the light, and
some of the light may be directed down the vertical part of the
T-shaped chamber 110 to strike the photocell 155. When sufficient
light hits the photocell 155, the current triggers the controller
38 to initiate the deflagration prevention cycle.
[0024] For the described photoelectric detector, the controller 38
may have a memory in which it stores a range of values
representative of a normal output of a photocell 55 when light
transmits normally and no fire exists. The controller 38 may
compare the stored values representative of the normal output range
and the actual output received from the photocell 55 to detect the
presence of a fire in the dryer 10. The controller 38 may determine
if the actual output received is less than the stored values
representative of the normal output range of the photocell 55 to
determine the presence or likelihood of a fire. The predetermined
range of values representative of a normal output of a photocell 55
and thus the threshold values to determine if a fire exists may be
empirically or otherwise determined. A normal output of a photocell
55 may be determined empirically for each type of photocell to be
used.
[0025] FIG. 5 is a representation of the data output of a photocell
55 as a function of time. The large decline at point A illustrates
a typical output of a photocell 55 when smoke blocks the
transmitted light from the light source 53. At this point, a fire
may have started and the sensor may output a signal indicative of a
fire or smoke or the controller may be receiving the signal and
determine that a fire or smoke is indicated. A large shift from the
normally expected output of the photocell 55, or a drop below some
empirically determined threshold, indicates a fire exists.
[0026] In operation, a user fills the drum 34 with a fabric load,
selects a cycle, and enters user inputs, such as the desired
dryness level and the load size, through the control panel 14. When
the drying cycle begins, the controller 38 activates the heater 36
to begin a heating cycle. The photocell 55 detects the light
emitted from the light source 53 and communicates the signal
strength to the controller 38. If the signal strength is above the
determined threshold, then the controller 38 continues to evaluate
the signal strength output from the photocell 55 for so long as the
dryer 10 remains in operation. If the signal strength may be
determined to be below the allowable threshold then the controller
38 invokes a suitable deflagration prevention cycle. In one
embodiment of the invention, normal use of the dryer may be
intentionally disabled by the controller 38 after the deflagration
prevention cycle initiates and service will have to be provided
before the dryer 10 may become operational again.
[0027] FIG. 6 provides a flow chart corresponding to an exemplary
method for preventing deflagration 200 of the dryer 10 according to
an embodiment of the invention. The method for preventing
deflagration 200 may be implemented in any suitable manner, such as
an automatic cycle of the dryer 10 that continuously runs as long
as the dryer 10 remains in operation. The method for preventing
deflagration 200 begins with a first determination at a step 202 of
whether a fire or the potential for a fire exists based on the fire
detector. If a fire exists then the door 16 may be locked at a step
204. After the door 16 locks in step 204 additional steps may
follow such as terminating the operation of the heater in step 206,
which may be done by shutting off or terminating power to the
heater 36, terminating operation of the fan in step 208, which may
be done by shutting off or terminating the fan, and terminating
operation of the entire dryer, which may be done by shutting off or
terminating power to the entire dryer in step 210.
[0028] Other steps may also be taken as part of the deflagration
prevention cycle 100. For example, an alarm may be sounded to alert
the user or anyone near by. If the appliance has a data or voice
communication functionality, a suitable alarm may be sent to a
remote location, which may include the consumer, a security service
provider, or a local emergency response team, such as the police or
fire departments.
[0029] While the invention has been specifically described in
connection with certain specific embodiments thereof, it may be
understood that this is by way of illustration and not of
limitation, and the scope of the appended claims should be
construed as broadly as the prior art will permit. For example, the
order of the steps 204 through 210 may be changed without affecting
the invention.
* * * * *