U.S. patent application number 13/216908 was filed with the patent office on 2012-03-01 for multi-port ignition system for a sectional furnace.
This patent application is currently assigned to Carrier Corporation. Invention is credited to William J. Roy, Kevin D. Thompson, Gary D. Wedlake.
Application Number | 20120052454 13/216908 |
Document ID | / |
Family ID | 45697724 |
Filed Date | 2012-03-01 |
United States Patent
Application |
20120052454 |
Kind Code |
A1 |
Roy; William J. ; et
al. |
March 1, 2012 |
Multi-Port Ignition System for a Sectional Furnace
Abstract
An ignition system for a gas furnace being controlled by a main
controller and having at least one burner is provided. The ignition
system may include at least one flame sensor and an interface
module. The flame sensor may be disposed in close proximity to the
burner and configured to output a flame check signal indicative of
a status of a flame at the burner. The interface module may be
configured to receive the flame check signal and generate a fault
check signal based on the flame check signal.
Inventors: |
Roy; William J.; (Avon,
IN) ; Thompson; Kevin D.; (Indianapolis, IN) ;
Wedlake; Gary D.; (Huntington, IN) |
Assignee: |
Carrier Corporation
Farmington
CT
|
Family ID: |
45697724 |
Appl. No.: |
13/216908 |
Filed: |
August 24, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61376560 |
Aug 24, 2010 |
|
|
|
Current U.S.
Class: |
431/74 ; 431/2;
431/78 |
Current CPC
Class: |
F23D 2207/00 20130101;
F23N 2237/02 20200101; F23N 2229/16 20200101; F23N 2229/12
20200101; F23N 2231/12 20200101; F23N 5/242 20130101; F23N 2227/02
20200101; F23D 23/00 20130101; F23D 2208/00 20130101 |
Class at
Publication: |
431/74 ; 431/78;
431/2 |
International
Class: |
F23N 5/00 20060101
F23N005/00 |
Claims
1. An ignition system for a gas furnace being controlled by a main
controller and having at least one burner, comprising: at least one
flame sensor disposed in close proximity to the burner, the flame
sensor being configured to output a flame check signal indicative
of a status of a flame at the burner; and an interface module
configured to receive the flame check signal, the interface module
configured to generate a fault check signal based on the flame
check signal, the interface module configured to output the fault
check signal.
2. The ignition system of claim 1, wherein the interface module is
configured to output the fault check signal to the main
controller.
3. The ignition system of claim 2, wherein the main controller is
in electrical communication with at least one igniter, the main
controller being configured to selectively ignite the igniter based
on the fault check signal.
4. The ignition system of claim 2, wherein the main controller is
configured to selectively turn off gas flow to the burner based on
the fault check signal.
5. The ignition system of claim 1, wherein the interface module is
in electrical communication with at least one igniter, the
interface module being configured to selectively ignite the igniter
based on at least one of the fault check and flame check
signals.
6. The ignition system of claim 2, wherein the interface module is
configured to selectively instruct the main controller to turn off
gas flow to the burner based on the fault check signal.
7. The ignition system of claim 1 further comprising one or more
additional flame sensors, the additional flame sensors configured
to output one or more additional flame check signals.
8. The ignition system of claim 7, wherein the interface module
comprises a multiplexer configured to receive the flame check
signals and generate the fault check signal based on all of the
flame check signals, the fault check signal indicating a normal
condition only if all flame check signals indicate presence of a
flame, the fault check signal indicating an abnormal condition if
at least one flame check signal does not indicate presence of a
flame.
9. The ignition system of claim 1, wherein the flame sensor is
configured to detect presence of a flame using one or more of flame
heat and flame light.
10. The ignition system of claim 1, wherein the flame sensor is
configured to detect presence of a flame using flame
rectification.
11. An ignition system for a gas furnace being controlled by a main
controller and having a plurality of burners, comprising: a
plurality of flame sensors wherein each flame sensor is disposed in
close proximity to its corresponding burner, each flame sensor
being configured to output a flame check signal indicative of a
status of a flame at its corresponding burner; and an interface
module configured to receive the flame check signals provided by
the plurality of flame sensors and output a fault check signal, the
interface module comprising a multiplexer configured to generate
the fault check signal based on the flame check signals.
12. The ignition system of claim 11, wherein the interface module
is in electrical communication with at least one igniter, the
interface module being configured to selectively ignite the igniter
based on at least one of the flame check signals.
13. The ignition system of claim 11, wherein the main controller is
in electrical communication with at least one igniter, the main
controller being configured to receive the fault check signal and
selectively ignite the igniter based on the fault check signal.
14. The ignition system of claim 11, wherein the fault check signal
indicates a normal condition only if all flame check signals
indicate presence of a flame, the fault check signal indicating an
abnormal condition if at least one flame check signal does not
indicate presence of a flame.
15. The ignition system of claim 14, wherein, in the abnormal
condition, the interface module is configured to determine the
burner that does not have a flame and generate signals to re-ignite
that burner.
16. The ignition system of claim 14, wherein the interface module
is configured to output the fault check signal to the main
controller, the main controller being configured to turn off gas
flow to the burners if the fault check signal indicates an abnormal
condition.
17. The ignition system of claim 11, wherein the flame sensors are
configured to detect presence of a flame using flame
rectification.
18. A method for providing a multi-port ignition system to a gas
furnace having a plurality of burners and corresponding igniters,
comprising the steps of: providing a flame sensor in close
proximity to each burner, each flame sensor configured to output a
flame check signal indicative of a status of a flame at each
burner; determining if flames are expected in the burners;
monitoring the flame check signals; indicating a normal condition
if flames are expected and if all flame check signals indicate
presence of a flame; indicating a normal condition if flames are
not expected and if none of the flame check signals indicate
presence of a flame; indicating an abnormal condition if flames are
expected but not all flame check signals indicate presence of a
flame; and indicating an abnormal condition if flames are not
expected but at least one flame check signal indicates presence of
a flame.
19. The method of claim 18 further comprising the steps of:
continuing furnace operation if a normal condition is indicated;
and shutting off gas flow to the burners if an abnormal condition
is indicated.
20. The method of claim 18 further comprising the steps of:
temporarily disabling the flame sensors if a normal condition is
indicated; monitoring the flame check signals; re-enabling the
flame sensors and continuing furnace operation if none of the flame
check signals indicate presence of a flame; and turning off gas
flow to the burners if at least one flame check signal indicates
presence of a flame.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This is a non-provisional U.S. patent application, which
claims priority under 35 U.S.C. .sctn.119(e) to U.S. Provisional
Patent Application Ser. No. 61/376,560 filed on Aug. 24, 2010, the
entirety of which is incorporated by reference herein.
FIELD OF THE DISCLOSURE
[0002] The present disclosure generally relates to ignition
systems, and more particularly, to multi-port ignition arrangements
for sectional gas furnaces.
BACKGROUND OF THE DISCLOSURE
[0003] Sectional gas furnaces are well known in the art and are
commonly used in residential applications to supply heat. These
furnaces typically employ a multiple heat exchanger configuration
in which the inlet of each heat exchanger is provided with its own
individual burner. In such an arrangement, only the endmost burner
is provided with an igniter and the remaining burners are lit using
a flame carryover mechanism. As illustrated in the prior art
embodiment of FIG. 1, the flame carryover mechanism 2 employs a
small channel 4 that interconnects each of the burners 6-8. Once
the endmost burner 6 is ignited, the small channel 4 serves to
transfer hot gases to the remaining burners 7, 8 so as to ignite
all of the burners 6-8 in succession. Currently existing systems
also employ one flame sensing mechanism to monitor the general
status of the flames and to promote efficient combustion of gases.
While these sectional gas furnaces perform with a degree of
efficiency and robustness, there is still room for improvement.
[0004] Sectional gas furnaces rely upon one igniter and a flame
sensing mechanism to monitor the status of the multiple flames.
Flame sensing technologies may be implemented using a single
infrared (IR) sensor, an IR emitter/sensor pair, a flame
rectification configuration, or the like. Although a single flame
sensor may adequately determine a general joint status of the
flames, present technologies lack the resolution to accurately and
quickly discern the status of each and every flame. For example, a
single flame sensor may be unable to detect a fault condition in
which only one of the burners is missing a flame. Even if it can
detect such a fault condition, the single flame sensor may be
unable to determine the faulty burner that is missing a flame. Such
failures can result in inefficient combustion of the gases.
[0005] Furthermore, as with any combustion device, the combustion
of gases within sectional gas furnaces results in unwanted
emissions. Of particular concern are nitric oxide (NO) and nitrogen
dioxide (NO2) emissions because of their roles in forming ground
level smog and acid rain as well as depleting the stratospheric
ozone. For simplicity, NO and NO2 are often grouped together as
NOx. With the increase in concerns to minimize atmospheric
pollution, many jurisdictions have stringent NOx emissions
regulations. For example, the state of California limits NOx
emissions from gas furnaces to a maximum of 40 ng/J. It is expected
that over the coming years, the regulations will become
increasingly more stringent and more widely accepted.
[0006] One way to substantially reduce NOx emissions is to fully
premix the fuel and air before combustion. This requires the
majority of the air that is used for combustion to be supplied with
gas flow, and further, requires the secondary air to be minimized.
However, the flame carryover mechanism in currently existing
sectional gas furnaces makes it extremely difficult to implement in
such premix configurations. More specifically, the considerable
amount of space between each premix burner in sectional
applications makes it difficult to maintain proper ignition of the
flames in the burner-to-burner configuration, and the space
occupied by the flame carryover mechanism itself makes it difficult
to effectively manage any secondary air.
[0007] It is therefore an object of the present disclosure to
provide an ignition apparatus and method that optimizes premix
combustion and minimizes NOx emissions. Moreover, there is a need
for an ignition system that provides individualized and improved
management of flame control to ensure proper combustion at each
individual burner. There is also a need for an ignition system that
overcomes the deficiencies of premix flame carryover mechanisms and
allows for a significant reduction in space between each burner and
its associated heat exchanger.
SUMMARY OF THE DISCLOSURE
[0008] In accordance with one aspect of the disclosure, an ignition
system for a gas furnace being controlled by a main controller and
having at least one burner is provided. The ignition system may
comprise at least one flame sensor and an interface module. The
flame sensor may be disposed in close proximity to the burner and
configured to output a flame check signal indicative of a status of
a flame at the burner. The interface module may be configured to
receive the flame check signal and generate a fault check signal
based on the flame check signal. The interface module may further
be configured to output the fault check signal.
[0009] In accordance with another aspect of the disclosure, another
ignition system for a gas furnace being controlled by a main
controller and having a plurality of burners is provided. The
ignition system may comprise a plurality of flame sensors and an
interface module. Each flame sensor may be disposed in close
proximity to its corresponding burner and configured to output a
flame check signal indicative of a status of a flame at its
corresponding burner. The interface module may be configured to
receive the flame check signals provided by the flame sensors and
output a fault check signal. The interface module may further
comprise a multiplexer configured to generate the fault check
signal based on the flame check signals.
[0010] In accordance with yet another aspect of the disclosure, a
method for providing a multi-port ignition system to a gas furnace
having a plurality of burners and corresponding igniters is
provided. The method may comprise the steps of: providing a flame
sensor in close proximity to each burner, wherein each flame sensor
may be configured to output a flame check signal indicative of a
status of a flame at each burner; determining if flames are
expected in the burners; monitoring the flame check signals;
indicating a normal condition if flames are expected and if all
flame check signals indicate presence of a flame; indicating a
normal condition if flames are not expected and if none of the
flame check signals indicate presence of a flame; indicating an
abnormal condition if flames are expected but not all flame check
signals indicate presence of a flame; and indicating an abnormal
condition if flames are not expected but at least one flame check
signal indicates presence of a flame.
[0011] These and other aspects of this disclosure will become more
readily apparent upon reading the following detailed description
when taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a perspective view of a prior art ignition system
for a gas furnace having a flame carryover mechanism;
[0013] FIG. 2 is partial perspective view of a sectional gas
furnace having an exemplary multi-port ignition system;
[0014] FIG. 3 is an exemplary schematic of the ignition system of
FIG. 2;
[0015] FIG. 4 is an exemplary schematic of the interface module of
FIG. 3; and
[0016] FIG. 5 is an exemplary algorithm for managing a gas furnace
having the ignition system FIG. 2.
[0017] While the present disclosure is susceptible to various
modifications and alternative constructions, certain illustrative
embodiments thereof have been shown in the drawings and will be
described below in detail. It should be understood, however, that
there is no intention to be limited to the specific forms
disclosed, but on the contrary, the intention is to cover all
modifications, alternative constructions, and equivalents falling
with the spirit and scope of the present disclosure.
DETAILED DESCRIPTION
[0018] Referring to the drawings and with particular reference to
FIG. 2, an exemplary ignition system for a gas furnace is provided
and referred to as reference number 16. It is understood that the
teachings of the disclosure may be used to construct ignition
systems above and beyond those specifically disclosed below. One of
ordinary skill in the art will readily understand that the
following are only exemplary embodiments.
[0019] Turning to FIG. 2, a typical sectional gas furnace 10 is
provided having one or more burners 12 each corresponding to one or
more heat exchangers (not shown) that may be disposed within the
gas furnace 10. Each of the burners 12 may be individually provided
with a corresponding igniter 14, or alternatively, the burners 12
may share a single igniter 14. Each igniter 14 may be positioned in
close proximity to an inlet of its corresponding burner 12 and
adapted to ignite a flame using a spark gap, or the like. The gas
furnace 10 may also be provided with an ignition system 16, as
partially shown in FIG. 2. The ignition system 16 may include a
plurality of flame sensors 18. Each flame sensor 18 may be
positioned in close proximity to an interior of its corresponding
burner 12 and configured to detect the presence of a flame therein.
The flame sensors 18 may employ an ultraviolet (UV) sensor, an
infrared sensor (IR), a combination UV/IR sensor, a combination
IR/IR sensor, a combination IR/IR/IR sensor, a bi-metallic strip,
an optical sensor, a flame rectification configuration or any other
suitable sensing mechanism configured to output a signal indicative
of the status of a flame in the respective burner 12. In
alternative embodiments, the ignition system 16 may provide one
flame sensor 18 for use with a gas furnace 10 having several
burners 12, or the ignition system 16 may provide several redundant
flame sensors 18 for use with a gas furnace 10 having only one
burner 12.
[0020] Still referring to FIG. 2, each of the burners 12 may be
provided with one igniter 14 so as to eliminate the need for a
flame carryover mechanism. By eliminating flame carryover, the
ignition system 16 may ensure proper and consistent ignition of
flames within each burner 12 and significantly reduce the size of
the secondary air gap, or the space between a burner 12 and the
inlet of its corresponding heat exchanger. Moving the burners 12
closer to the heat exchangers may further serve to direct more
combustion products into the heat exchangers, and thus, promote
more efficient thermal management thereof. Additionally, by
providing a flame sensor 18 to each individual burner 12, the
ignition system 16 may enable quicker and more accurate detection
of flames in each burner 12 or the lack thereof. In such a way, the
ignition system 16 may significantly increase furnace efficiency
and effectively reduce NOx emissions.
[0021] Turning now to FIG. 3, an exemplary interface module 20 of
the ignition system 16 is provided. As shown, the interface module
20 may serve to communicate information between a main controller
22 of the gas furnace 10 and the flame sensors 18 of the ignition
system 16. In alternative embodiments, the interface module 20 may
also be configured to communicate directly with the igniters 14
and/or to communicate information between the main controller 22
and the igniters 14. Each igniter 14 may be controlled by an
optional remote 24 for selectively igniting a flame in its
respective burner 12. Depending on the desired application, each
remote 24 may be operated by the main controller 22 and/or by the
interface module 20 of the ignition system 16. Furthermore, each
flame sensor 18 may be configured to output a flame check signal
A1-A4 to the interface module 20 that is indicative of a status of
a flame at its corresponding burner 12. The flame check signal
A1-A4 may be an electrical voltage and/or current signal of a
predefined magnitude and/or frequency that is responsive to light
and/or heat emitted from an existing flame. Based on the flame
check signals A1-A4, an interface circuit 26 of the interface
module 20 may generate and transmit a fault check signal A5, A6 to
the main controller 22 for further processing. In response to the
fault check signal A5, A6, the main controller 22 may be configured
to continue normal furnace operation, attempt re-ignition of one or
more burners 12, indicate a furnace failure alert, turn off gas
flow to the burners 12, turn off all furnace operations, or the
like. The interface circuit 26 may optionally provide a multiplexer
27 configured to receive one or more flame check signals A1-A4 and
to generate one or more fault check signals A5, A6 based on the
combination of the flame check signals A1-A4 received. For example,
the multiplexer 27 may be configured such that it outputs a fault
check signal A5, A6 enabling the main controller 22 to continue
normal furnace operation if and only if all flame check signals
A1-A4 indicate that a flame is present. If any flame check signal
A1-A4 indicates that a flame is not present at its respective
burner 12, the multiplexer 27 may output a fault check signal A5,
A6 which turns off gas flow to the burners 12, halts all furnace
operations, or the like.
[0022] Turning to FIG. 4, an exemplary schematic for implementing
the ignition system 16 is provided. As shown, the ignition system
16 may include one or more flame sensors 18, wherein each flame
sensor 18 is provided with a flame rod 28 and a flame sense circuit
29. The flame rods 28 may provide means for detecting a flame and
may be disposed in close proximity to the burners 12. The flame
sense circuits 29 may generate flame check signals A1-A4 that are
responsive to the flames detected at the flame rods 28. The flame
check signals A1-A4 may be routed to an interface circuit 26 of the
interface module 20 for further processing. Additionally, power
supplied to the flame sense circuits 29, for example, 120 VAC, may
be selectively enabled or disabled via a switch, relay, or the
like, coupled to an input signal A7. Power to the flame sense
circuits 29 and thus the flame rods 28 may be temporarily enabled
or disabled via input signal A7 by the main controller 22 or the
interface module 20 for diagnostic purposes, or the like.
[0023] As shown for example in FIG. 4, the interface circuit 26 may
include a series of logic gates 30, 31 that are configured to
output at least two binary fault check signals A5, A6. In the
example shown, each flame sensor 18 and associated flame sense
circuit 29 may be configured to output a logical high value when a
flame is detected. In such a case, the first signal A5 of the
interface circuit 26 may be set to a logical high value only when
all four flame sensors 18 indicate a lit flame, and the second
signal A6 may be set to a logical high value when any of the four
flame sensors 18 indicate a lit flame. Correspondingly, the first
signal A5 may indicate a logical low value when any of the flame
sensors 18 indicate an unlit flame, and the second signal A6 may
indicate a logical low value only when all of the flame sensors 18
indicate an unlit flame. The signals that are output by the
interface circuit 26, such as fault check or binary signals A5, A6
of FIG. 4, may be routed to the main controller 22 for further
analysis. Based on the conditions these signals indicate, the main
controller 22 may be able to determine if there is an error or
fault, or if there is a normal or abnormal condition, and respond
accordingly.
[0024] Referring now to FIG. 5, an exemplary algorithm for managing
a gas furnace 10 having an ignition system 16 is illustrated. As
shown, the algorithm may begin in a base or first mode B1 wherein
the algorithm may determine if flames are expected in the
respective burners 12. If no flames are expected, the algorithm may
proceed to a second mode B2 to ensure that there are no flames and
that all burners 12 are indeed off. For example, the algorithm may
scan the flame check signals A1-A4 and/or fault check signals A5,
A6 to determine if any flame is lit. If any of the signals A1-A6
indicate that a flame is present, the algorithm may indicate a
fault or an abnormal condition and disable all gas flow
accordingly. The algorithm may then return to the first mode B1
until the abnormal condition has cleared. However, if all flames
are confirmed to be off, the algorithm may indicate a safe or
normal condition and return to the first mode B1.
[0025] If flames are expected during the first mode B1, the
algorithm may proceed to a third mode B3 to determine if all flames
in the burners 12 are lit and stable. Specifically, the algorithm
may refer to the interface module 20 to determine if the fault
check signals A5, A6 indicate that each and every flame is lit. If
the fault check signals A5, A6 indicate that at least one flame is
not lit, the algorithm may indicate a fault or an abnormal
condition and disable all gas flow. The algorithm may then return
to the first mode B1 until the abnormal condition has cleared.
Alternatively, the algorithm may determine the particular burner 12
that is missing a flame and proceed to re-ignite that burner 12
until a stable flame is detected.
[0026] If the fault check signals A5, A6 confirm that all flames
are lit, the algorithm may set a timer for a predefined duration
and remain in the third mode B3 until the timer ends. Once the
timer ends, the algorithm may proceed to a fourth mode B4 to test
the functionality of the flame rods 28 and/or flame sense circuits
29. In particular, the algorithm may temporarily disable the flame
sense circuits 29 via, for example, the input signal A7, and
determine if the fault check signals A5, A6 indicate that all
flames are unlit. The flame sense circuits 29 may be configured
such that they output fault check signals (A5, A6) that are null,
or signals indicating no flames, when powered off. By cutting power
to the flame sense circuits 29, the algorithm may be able to
determine if the flame sense circuits 29 are operational and
indicate no flame at the burners 12, or if they are faulty and
indicate otherwise. If the fault check signals A5, A6 indicate any
flame after cutting power to the flame sense circuits 29, the
algorithm may indicate a fault or abnormal condition and disable
all gas flow. The algorithm may then return to the first mode B1
until the abnormal condition has cleared. If, however, the fault
check signals A5, A6 are null, the algorithm may indicate a safe or
normal condition, re-enable power to the flame sense circuits 29,
return to the first mode B1 and continue normal furnace
operation.
[0027] Based on the foregoing, it can be seen that the present
disclosure provides individualized and improved management of flame
control to ensure proper combustion at each individual burner of a
gas furnace. The present disclosure also eliminates the need for
flame carryover mechanisms and allows for a significant reduction
in space between each burner and its associated heat exchanger.
[0028] While only certain embodiments have been set forth,
alternatives and modifications will be apparent from the above
description to those skilled in the art. These and other
alternatives are considered equivalents and within the spirit and
scope of this disclosure.
* * * * *