U.S. patent application number 11/308646 was filed with the patent office on 2006-10-19 for burner shut off.
Invention is credited to Eric Willms.
Application Number | 20060234176 11/308646 |
Document ID | / |
Family ID | 37114230 |
Filed Date | 2006-10-19 |
United States Patent
Application |
20060234176 |
Kind Code |
A1 |
Willms; Eric |
October 19, 2006 |
BURNER SHUT OFF
Abstract
A burner shutoff for a burner, the burner shutoff including a
solenoid moveable between an open position permitting fuel supply
to the burner and a closed position cutting off fuel supply to the
burner. The burner shutoff including a thermocouple in
communication with the solenoid, wherein the thermocouple producing
a voltage output signal when heated by the burner for maintaining
the solenoid in the open position. The burner including a safety
timer for selectively generating and communicating a reverse
polarity voltage signal to the solenoid such that the voltage
signal received by the solenoid is altered sufficiently to move the
solenoid to the closed position, thereby shutting off the
burner.
Inventors: |
Willms; Eric; (Stoney Creek,
CA) |
Correspondence
Address: |
MARK A KOCH
866 MAIN STREET EAST
HAMILTON
ON
L8M1L9
CA
|
Family ID: |
37114230 |
Appl. No.: |
11/308646 |
Filed: |
April 17, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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60672542 |
Apr 19, 2005 |
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Current U.S.
Class: |
431/80 |
Current CPC
Class: |
F23N 5/203 20130101;
F23N 5/102 20130101 |
Class at
Publication: |
431/080 |
International
Class: |
F23N 5/10 20060101
F23N005/10 |
Claims
1. A burner shutoff for a portable heater comprising; (a) a burner
including a solenoid moveable between an open position permitting
fuel supply to the burner and a closed position cutting off fuel
supply to the burner; (b) a thermocouple in communication with the
solenoid, wherein the thermocouple producing a voltage output
signal when heated by the burner for maintaining the solenoid in
the open position; (c) a safety timer for selectively generating
and communicating a reverse polarity voltage signal to the solenoid
such that the voltage signal received by the solenoid is altered
sufficiently to move the solenoid to the closed position, thereby
shutting off the burner.
2. The burner shutoff claimed in claim 1, wherein the safety timer
including a timer for operably communicating the reverse polarity
voltage signal at pre selected times.
3. The burner shutoff claimed in claim 2 wherein the safety timer
including a micro processor for initiating a pre selected timed
interval thereby operably communicating the reverse polarity
voltage signal at the end of the pre selected timed interval.
4. The burner shutoff claimed in claim 3, wherein the safety timer
including a self contained power supply.
5. The burner shutoff claimed in claim 3, wherein the safety timer
including a self contained power supply including a battery.
6. The burner shutoff claimed in claim 4, wherein the safety timer
including a power storage device which is activated upon failure of
the self contained power supply and will provide enough power for
operably communicating the reverse polarity voltage signal to the
solenoid, thereby shutting off the burner.
7. The burner shutoff claimed in claim 1, wherein the thermocouple
connected to the solenoid with thermocouple wires.
8. The burner shutoff claimed in claim 7, wherein thermocouple
wires being continuous between the solenoid and thermocouple.
9. The burner shutoff claimed in claim 8, wherein the safety timer
connected to the thermocouple wires with timer wires at a contact
less connection without introducing additional contact resistance
along the thermocouple wires.
10. A method of shutting off a burner, the method comprising:
configuring a burner to comprise, a solenoid moveable between an
open position permitting fuel supply to the burner and a closed
position cutting off fuel supply to the burner, a thermocouple in
communication with the solenoid, wherein the thermocouple producing
a voltage output signal when heated by the burner for maintaining
the solenoid in the open position; (a) igniting the burner, (b)
generating a reverse polarity output signal, (c) communicating the
reverse polarity voltage signal to the solenoid such that the
voltage signal received by the solenoid is altered sufficiently to
move the solenoid to the closed position, thereby shutting off the
burner.
11. The method claimed in claim 10 wherein step a) is as follows:
(a) generating a reverse polarity output signal at a selected time
controlled by a safety timer which is in communication with the
solenoid.
12. The method claimed in claim 11 wherein the safety timer
including a self contained power supply.
13. The method claimed in claim 11 wherein the thermocouple
connected to the solenoid with thermocouple wires and the safety
timer connected to the thermocouple wires with timer wires at a
contact less connection without introducing additional contact
resistance along the thermocouple wires.
14. A system for shutting off a burner comprising; (a) a burner
including a solenoid moveable between an open position permitting
fuel supply to the burner and a closed position cutting off fuel
supply to the burner; (b) a thermocouple in communication with the
solenoid, wherein the thermocouple producing a voltage output
signal when heated by the burner; wherein the voltage output signal
received by the solenoid maintaining it in the open position; (c) a
reset button for initiating a timer within a safety timer, the
safety timer for generating and communicating a reverse polarity
output signal to the solenoid such that the voltage signal received
by the solenoid is altered sufficiently to move the solenoid to the
closed position, thereby shutting off the burner.
15. The system claimed in claim 14 wherein upon expiration of the
timer the safety timer communicating the reverse polarity voltage
signal to the solenoid.
16. The system claimed in claim 15 wherein upon depressing the
reset button prior to expiration of the timer resets the timer back
to a pre determined value.
17. The system claimed in claim 14 wherein the safety timer
including a self contained power supply including a battery.
18. The system claimed in claim 17 wherein the safety timer
including a power storage device which is activated upon failure of
the self contained power supply and will provide enough power for
operably communicating the reverse polarity voltage signal to the
solenoid, thereby shutting off the burner.
19. The system claimed in claim 14 wherein the thermocouple
connected to the solenoid with thermocouple wires.
20. The system claimed in claim 19 wherein thermocouple wires being
continuous between the solenoid and thermocouple.
21. The system claimed in claim 20 wherein the safety timer
connected to the thermocouple wires with timer wires at a contact
less connection without introducing additional contact resistance
along the thermocouple wires.
Description
FIELD OF THE INVENTION
[0001] The present invention generally relates to a safety
automatic shut off device for gas burners.
BACKGROUND OF THE INVENTION
[0002] Heaters often utilize gas fired burners which normally
operate with propane fuel, however can also have other sources of
fuel, including but not limited to natural gas, butane and heating
oil. Most portable heaters having gas fired burners are fitted with
a safety thermocouple which communicates electrically with a
solenoid valve in order to detect a flame out condition. The
thermocouple mounted proximate the flame or heat source develops a
millivolt signal which in turn is communicated back to the solenoid
valve. The millivolt signal maintains the solenoid valve in the
open position. When a flame out condition occurs, the thermocouple
cools downs and the millivolt signal decreases which in turn closes
off the solenoid valve once the signal from the thermocouple has
dropped to a certain predetermined level.
[0003] Small heaters having gas fired burners are often used in
very small enclosed spaces and under the right conditions, the gas
fired burners may deplete the amount of oxygen within the enclosed
space and under certain conditions may give off carbon monoxide
which can be hazardous to the occupant of the enclosed space.
[0004] Therefore it is desirable to have a safety device and/or a
safety feature which will prevent or minimize the possibility of
oxygen depletion within small enclosed spaces and/or the
development of carbon monoxide in order to prevent hazardous
conditions from forming within small enclosed spaces in which the
heaters are located.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] The embodiments now be described by way of example only with
reference to the following diagrams in which:
[0006] FIG. 1 is a schematic diagram of the burner shut off as
shown deployed with a heater.
[0007] FIG. 2 is a schematic wiring diagram of the burner shut off
showing details of the wiring of the safety timer.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0008] The present embodiment of burner shut off is shown generally
as 100 in FIGS. 1 and 2. In FIG. 1, burner shut off 100 is shown
deployed together with a heater 102. In one example heater 102 is a
portable space heater of the type having a high intensity ceramic
type gas burner. Burner shut off 100 may also be applicable to
other heaters.
[0009] Burner shut off 100 includes safety timer 202 which includes
circuit board 214 having the following major components, namely a
timer 204, a micro processor 206, a power storage device 208 and a
power supply preferably a battery 212.
[0010] The burner shut off 100 further includes a thermocouple 220
having thermocouple wires 222 in electrical communication with
solenoid valve 230 which also has a manual push button 232.
[0011] Safety timer 202 is in electrical communication with
thermocouple wires 222 via timer wires 216.
[0012] Typical heater 102 includes a gas supply 110, burner 116
producing a flame 118.
[0013] Certain components of heater 102 are not shown for
simplicity sake for example, the mixing of air with gas supply 110
is not shown and also the ignition source for lighting flame 118 is
also not shown. The components of heater 102 which interact with
burner shut off 100 are generally shown namely burner 116 having
flame 118 as well as solenoid valve 230.
In Use
[0014] Heater 102 is started in the manner generally known in the
art namely, manual push button 232 of solenoid valve 230 is
manually depressed in order to allow gas supply 110 to flow freely
to burner 116. Not shown, gas is mixed in appropriate proportions
with air in order to produce a combustible mixture of fuel and air
which can be ignited at the end of burner 116 to produce flame 118.
An ignition source not shown is used to ignite the combustible fuel
mixture at the end of burner 116 to produce flame 118. Once flame
118 has been initiated, it heats thermocouple 220 and the heating
of thermocouple 220 creates a millivolt output normally in the
range between 0.007 to 0.020 volts (7 to 20 millivolts) and this
potential produced by thermocouple 220 is electrically communicated
back to solenoid 230. The millivolt out of thermocouple 220 is
enough to hold the solenoid valve 230 in the open position allowing
gas supply 110 to flow freely to burner 116.
[0015] A person skilled in the art will recognize that once
thermocouple 220 has been heated to the normal operating
temperature by flame 118, enough millivolts and/or current are
produced by thermocouple 220 to hold solenoid valve 230 in the open
position, and therefore manual push button 232 can be released and
the valve 230 is retained in the open position to ensure continuous
firing of burner 116.
[0016] Thermocouple 220 is there to ensure that should for some
reason flame 118 be extinguished, thermocouple 220 will naturally
cool down and therefore the millivolts produced by thermocouple 220
will decrease to a point where the current produced by thermocouple
220 can no longer hold solenoid valve 230 in the open position and
therefore, gas supply 110 will be shut off. A person skilled in the
art will recognize this as a normal safety feature that is found on
many commercially available portable space heaters for safety
purposes to ensure that the gas supply 110 is cut off should there
be an interruption or an extinguishment of flame 118.
[0017] A person skilled in the art will recognize that the
electromotive force or the voltage output of thermocouple 220 is
extremely low, normally in the range of 7 to 20 millivolts and once
the voltage falls below about 5 millivolts the solenoid valve 230
will normally trip to the closed position.
[0018] A person skilled in the art will also recognize that due to
the small millivolt output of thermocouple 220, the electrical
connections between thermocouple 220 and solenoid valve 230 are
extremely sensitive, particularly to any contact resistance which
may inhibit the flow of current between thermocouple 220 and
solenoid valve 230 along thermocouple wires 222. Therefore, any
mechanical contact which is introduced between thermocouple 220 and
solenoid valve 230 may be undesirable in that it may introduce an
unwanted contact resistance and falsely close solenoid valve 230
when in fact, flame 118 has not been extinguished.
[0019] Therefore in one embodiment a burner shut off 100 is
contemplated which will allow solenoid valve 230 to shut gas supply
110 without introducing any mechanical contact resistance of
additional switches or contacts along thermocouple wires 222. In
other words thermocouple wires 222 are continuous and free of
intervening contacts between thermocouple 220 and solenoid valve
230 in order to ensure the most reliable operation of heater 102.
This continuous aspect of thermocouple wires 222 means there are no
mechanical contacts introduced between thermocouple 220 and
solenoid 230 other than to accomplish connection between
thermocouple 222 and solenoid 230. The connection between the timer
wires 216 and thermocouple wires 222 does not introduce a
mechanical contact and therefore no additional contact resistance
along thermocouple wires 222. The timer wires 216 are connected to
the thermocouple wires using a contact less connection 219. The
contact less connection can be in any location provided a
connection is made to the solenoid 230. In another embodiment it is
contemplated that contacts may be used provided the contact
resistance does not falsely close solenoid valve 230.
[0020] One embodiment includes a safety timer 202 which consists of
a circuit board 214 having thereon a timer 204 which is electronic
in nature and furthermore includes a micro processor 206, and
further includes a power storage device 208 and has a power supply
which could be a battery 212. Circuit board 214 further includes a
reset button 210 which is a manual push button or other type of
button and/or switch device which upon pushing of the reset button
210 initiates the timer cycle which may for example be a
preselected programmed amount of time through processor 206 and
timer 204.
[0021] For example, heater 102 is ignited and lit in the
conventional manner as described above by manually depressing
manual push button 232 igniting flame 118, wherein thermocouple 220
is brought up to temperature and the solenoid valve 230 is held
open by thermocouple 220 even after the release of manual push
button 232. At this point in time, heater 102 will continue to
operate until there is an interruption in the signals between
thermocouple 220 and solenoid valve 230.
[0022] Initiating the current between thermocouple 220 and solenoid
valve 230, acts to initiate the timer 204 of safety timer 202 which
provides for a preset amount of time before an event is triggered
by circuit board 214. So for example, by initiating firing of
burner 116, namely flame 118, the heater 102 will operate for
example for a period of 10 minutes as predetermined by
microprocessor 206 and timer 204 after which time safety timer 202
will create a reverse bias electromotive force (millivolt signal)
along timer wires 216 which effectively counteracts the millivolt
output developed by thermocouple 220. In other words a voltage
signal or electromotive force of about 20 millivolts (0.020 volts)
will be created across thermocouple wires 212 in reverse polarity
to the natural millivolt output of thermocouple 220, therefore the
applied voltage at solenoid 230 will in effect be reduced to zero
or very close to zero.
[0023] If in the above example, the operator presses reset button
210 prior to the expiry of the 10 minutes allotted by timer 204,
timer 204 together with microprocessor 206 is reset to allow for an
additional 10 minutes before an event is again triggered by safety
timer 202.
[0024] Upon expiration of the next 10 minutes, safety timer 202
will automatically create a millivolt signal across timer wires 216
which counteract the millivolt signal created by thermocouple 220,
therefore reducing the voltage seen by solenoid valve 230
effectively to zero, thereby causing gas supply 110 to be shut
off.
[0025] Therefore, heater 102 is allowed to operate for a maximum
time of 10 minutes unless resent button 210 is depressed prior to
the expiration of the preset time of 10 minutes.
[0026] Should a heater 102 be used in a confined space, and the
occupant for example become unconscious and unable to press reset
button 210, heater 102 will automatically be shut down by safety
timer 202, extinguishing flame 118 and shutting off gas supply
110.
[0027] If for some reason there is failure of the power supply,
namely battery 212 to circuit board 214, safety timer 202 will
detect this condition and there will be enough residual power
stored within power storage 208 to be able to send enough
electromotive force across timer wires 216 to counteract the
millivolt output generated by thermocouple 220 and therefore shut
down heater 102. The power storage 208 could be a capacitor or
inductor or a combination of electrical components which are
capable of storing enough residual power to produce the reverse
polarity voltage signal to close solenoid valve 230.
[0028] The cycle time of timer 204 is preselected depending upon
the application and can vary any where from a few seconds to many
hours. It normally is a pre-programmed amount of time however could
also be a selected value.
[0029] A person skilled in the art will immediately recognize that
the advantages of having an electrical connection between
thermocouple wires 212 and timer wires 216 which eliminates
mechanical switch contacts used to break the connection between
thermocouple 220 and solenoid valve 230. In one embodiment the
electrical connection between thermocouple 220 and solenoid valve
230, namely thermocouple wires 222 are not mechanically broken to
effect shut off. The shut off of solenoid valve 230 is accomplished
by permanent electrical connections between timer wire 216 and
thermocouple wires 222 by applying a reverse bias voltage to
thermocouple wires 222.
[0030] In addition, the safety timer 202 can operate very easily
with a portable battery power of for example three volts or less
creating a safety timer not depending on 110 volt AC line
current.
[0031] Additionally, this safety timer shut off device provides for
a low cost method of efficiently shutting down heater 102 and a
completely self contained apparatus not requiring any sources of
external power other than the self contained battery 212.
[0032] It should be apparent to persons skilled in the arts that
various modifications and adaptation of this structure described
above are possible without departure from the spirit of the
invention the scope of which defined in the appended claims.
* * * * *