U.S. patent application number 11/770014 was filed with the patent office on 2009-01-01 for gas-fired heating appliance having a flammable vapor sensor control device.
This patent application is currently assigned to THERM-O-DISC, INCORPORATED. Invention is credited to Jeffrey A. West.
Application Number | 20090004612 11/770014 |
Document ID | / |
Family ID | 40160995 |
Filed Date | 2009-01-01 |
United States Patent
Application |
20090004612 |
Kind Code |
A1 |
West; Jeffrey A. |
January 1, 2009 |
Gas-Fired Heating Appliance Having a Flammable Vapor Sensor Control
Device
Abstract
A gas-fired heating appliance includes a burner, a gas valve
module for supplying a fuel gas to the burner, a power module for
applying a voltage to the gas valve module, and a flammable vapor
sensor module for detecting a flammable vapor. The flammable vapor
sensor module interrupts the voltage to the gas valve to shut off
the gas valve and the burner when the flammable vapor module
detects the presence or a predetermined concentration of flammable
vapor. The voltage of the power module is applied to the gas valve
module through the flammable vapor sensor module. The voltage to
the gas valve module is interrupted if the flammable vapor sensor
module is short-circuited. This arrangement is tamper-resistant to
promote a safe operation of the gas-fired heating appliance.
Inventors: |
West; Jeffrey A.;
(Bellville, OH) |
Correspondence
Address: |
HARNESS, DICKEY & PIERCE, P.L.C.
P.O. BOX 828
BLOOMFIELD HILLS
MI
48303
US
|
Assignee: |
THERM-O-DISC, INCORPORATED
Mansfield
OH
|
Family ID: |
40160995 |
Appl. No.: |
11/770014 |
Filed: |
June 28, 2007 |
Current U.S.
Class: |
431/22 |
Current CPC
Class: |
F23N 1/002 20130101;
F23N 5/242 20130101; F23N 5/102 20130101; F23N 2235/14 20200101;
F23N 5/003 20130101; F23N 2229/02 20200101; F23N 2241/04
20200101 |
Class at
Publication: |
431/22 |
International
Class: |
F23N 5/24 20060101
F23N005/24 |
Claims
1. A control for a gas-fired heating appliance, comprising: a gas
valve module comprising a gas valve adapted to supply a fuel gas to
the gas-fired heating appliance; a flammable vapor sensor module
for detecting the presence of a flammable vapor in an operating
environment of the appliance; and a power module for providing an
input to the flammable vapor sensor module, the flammable vapor
sensor module providing an output to the gas valve module to
maintain the gas valve in an open state; wherein the flammable
vapor sensor module interrupts the output to the gas valve module
when a predetermined concentration of the flammable vapor is
detected.
2. The control of claim 1, wherein the power module includes a
thermocouple.
3. The control of claim 1, wherein the flammable vapor sensor
module includes a chemiresistor sensor, the resistance of which
changes in the presence of the flammable vapor.
4. The control of claim 1, wherein the gas valve module includes a
solenoid.
5. The control of claim 1, wherein the flammable vapor sensor
module includes a flammable vapor sensor circuit connected in
series with the power module.
6. The control of claim 1, wherein the flammable vapor sensor
module includes a flammable vapor sensor circuit connected in
parallel with the power module.
7. A gas-fired heating appliance, comprising: a fuel gas burner;
and a flammable vapor sensor control comprising: a gas valve module
including a gas valve adapted to supply a fuel gas to the burner
when in an open state; a flammable vapor sensor module for
detecting the presence of a flammable vapor in an operating
environment of the appliance, the flammable vapor sensor module
providing an output to the gas valve module to maintain the gas
valve in the open state; and a power module providing an input to
the flammable vapor sensor module; wherein the flammable vapor
sensor module interrupts the output to the gas valve module when
the flammable vapor sensor module detects a predetermined
concentration of the flammable vapor in the operating
environment.
8. The gas-fired heating appliance of claim 7, wherein the power
module includes a thermocouple.
9. The gas-fired heating appliance of claim 8, wherein the
thermocouple is heated by a pilot flame of the burner, the
thermocouple generating an electrical potential when heated.
10. The gas-fired heating appliance of claim 7, wherein the
flammable vapor sensor module includes a chemiresistive sensor, the
resistance of which changes in the presence of the flammable
vapor.
11. The gas-fired heating appliance of claim 7, wherein the gas
valve module includes a solenoid energized by the output of the
flammable vapor sensor module.
12. A flammable vapor sensor control system for a gas-fired heating
appliance, comprising: a power module comprising a thermocouple; a
flammable vapor sensor module operable to detect the presence of a
predetermined concentration of a flammable vapor within an
operating environment of the appliance; and a gas valve module
comprising a solenoid-actuated gas valve adapted to supply a fuel
gas to the gas-fired heating appliance when energized, wherein the
thermocouple generates an electrical potential, the electrical
potential applied to the flammable vapor sensor module, the
flammable vapor sensor module energizing the gas valve in a first
condition when a predetermined concentration of the flammable vapor
is not present in the operating environment of the appliance, and
de-energizing the gas valve in a second condition when a
predetermined concentration of the flammable vapor is present in
the operating environment of the appliance.
13. The flammable vapor sensor control system of claim 12, wherein
the electric circuit of the flammable vapor sensor module comprises
a chemiresistor sensor the resistance of which increases in the
presence of flammable vapor.
Description
FIELD
[0001] The present disclosure relates generally to gas-fired
heating appliances and their controls, and more particularly to
gas-fired heating appliance controls incorporating a flammable
vapor sensor control device.
BACKGROUND
[0002] The statements in this section merely provide background
information related to the present disclosure and may not
constitute prior art.
[0003] Residential and commercial gas-fired heating appliances,
such as water heaters, typically comprise a main burner and a
standing pilot burner disposed within a combustion chamber below a
cylindrical water tank. The main and standing pilot burners are
supplied with a fuel gas through a gas valve, and air through an
air inlet screen. Such standing pilot water heaters vent the
combustion air without the use of a fan, and operate independently
of the electrical power within the building. While conventional
water heater appliances of this type operate reliably and safely,
there may exist the possibility that the burners could cause
flammable vapors external to the appliance to be ignited. The
resulting flame could potentially propagate out of the appliance
into the ambient environment around the appliance.
[0004] Efforts to mitigate any potential hazard posed by the
presence of flammable vapors in proximity to a gas burning
appliance have been previously directed to a control circuit in
connection with a sensor that responds to the presence of flammable
vapors to effect a shut down of the burner (e.g., by closing the
gas valve). In a known flammable vapor sensor control circuit, the
sensor experiences a significant increase in electrical resistance
when it is exposed to a concentration of flammable vapors meeting a
predetermined threshold. In such an instance, the sensor element
cuts off the electrical current to a solenoid-actuated gas valve to
close the fuel gas supply to both the main burner and the standing
pilot burner, thereby shutting off the burners. The control circuit
can prevent further operation of the burners until service or
replacement of the control circuit or sensor.
[0005] While replacement of the sensor is a routine procedure to
restore operation of the burners, it is possible that an end user
may short-circuit the flammable vapor sensor control circuit as a
matter of convenience to restore operation of the gas-fired heating
appliance. As such, the appliance would operate without the
safeguard of the flammable vapor sensor control circuit, which is
undesirable.
SUMMARY
[0006] Several embodiments of the present disclosure provide for a
tamper-resistant flammable vapor sensor control device to promote
the safe operation of a gas-fired heating appliance. In one form, a
control device for a gas-fired heating appliance includes a gas
valve module, a flammable vapor sensor module and a power module.
The gas valve module includes a gas valve adapted to supply a fuel
gas to the gas-fired heating appliance. The flammable vapor sensor
module detects the presence of a flammable vapor in an operating
environment of the appliance. The power module provides an input to
the flammable vapor sensor module. The flammable vapor sensor
module provides an output to the gas valve module to maintain the
gas valve in an open state. The flammable vapor sensor module
interrupts the output to the gas valve module when a predetermined
concentration of a flammable vapor is detected.
[0007] In another form, a gas-fired heating appliance includes a
fuel gas burner and a flammable vapor sensor control device. The
flammable vapor sensor control includes a gas valve adapted to
supply a fuel gas to the burner when in an open state, a flammable
vapor sensor module for detecting the presence of a flammable vapor
in an operating environment of the appliance and a power module.
The flammable vapor sensor module provides an output to the gas
valve module to maintain the gas valve in the open state. The power
module provides an input to the flammable vapor sensor module. The
flammable vapor sensor module interrupts the output to the gas
valve module when the flammable vapor sensor module detects a
predetermined concentration of the flammable vapor in the operating
environment.
[0008] In yet another form, a flammable vapor sensor control system
for a gas-fired heating appliance includes a power module, a
flammable vapor sensor module and a gas valve module. The power
module includes a thermocouple. The flammable vapor sensor module
is operable to detect the presence of a predetermined concentration
of a flammable vapor within an operating environment of the
appliance. The gas valve module includes a solenoid-actuated gas
valve adapted to supply a fuel gas to the gas-fired heating
appliance when energized. The thermocouple generates an electrical
potential, which is applied to the flammable vapor sensor module.
The flammable vapor sensor module energizes the gas valve in a
first condition when a predetermined concentration of the flammable
vapor is not present in the operating environment of the appliance,
and de-energizes the gas valve in a second condition when a
predetermined concentration of the flammable vapor is present in
the operating environment of the appliance.
[0009] Further areas of applicability will become apparent from the
description provided herein. It should be understood that the
description and specific examples are intended for purposes of
illustration only and are not intended to limit the scope of the
present disclosure.
DRAWINGS
[0010] The drawings described herein are for illustration purposes
only and are not intended to limit the scope of the present
disclosure in any way.
[0011] FIG. 1 is a schematic illustration of a gas-fired heating
appliance employing a flammable vapor sensor control device in
accordance with the teachings of the present disclosure; and
[0012] FIG. 2 is a schematic diagram of a control device for a
gas-fired heating appliance in accordance with the teachings of the
present disclosure.
[0013] Corresponding reference numerals indicate corresponding
parts throughout the several views of the drawings.
DETAILED DESCRIPTION
[0014] The following description is merely exemplary in nature and
is not intended to limit the present disclosure, application, or
uses.
[0015] Referring to FIGS. 1 and 2, an exemplary gas-fired heating
appliance is illustrated and generally indicated by reference
numeral 10. The exemplary gas-fired heating appliance 10 takes the
form of a water heater and includes a cylindrical water tank 12 and
a main burner and a standing pilot burner (collectively burner 14)
disposed within a combustion chamber 16 at the bottom of the
appliance 10 below the cylindrical water tank 12 in a well-known
manner.
[0016] The gas-fired heating appliance 10 further includes a
control device 20 for the gas-fired heating appliance 10. The
control device 20 includes a power module 22, a flammable vapor
sensor module 24 and a gas valve module 26. The power module 22
includes a thermocouple 28 disposed adjacent to a pilot flame and
includes a pair of output terminals 30.
[0017] The gas valve module 26 includes a gas valve 32 for
supplying a fuel gas to the appliance 10 and a solenoid 34 for
energizing or de-energizing the gas valve 32. The gas valve module
26 controls the supply of a fuel gas through a supply line 36 to
the burner 14. The control device 20 includes a knob 38 that must
be depressed to supply the fuel gas while lighting a pilot burner
flame.
[0018] The flammable vapor sensor module 24 is connected between
the power module 22 and the gas valve module 26 for detecting the
presence of a flammable vapor 40 in an operating environment of the
appliance 10.
[0019] The flammable vapor sensor module 24 includes a
chemiresistor sensor 42 for detecting the presence of flammable
vapor 40. When the chemiresistor sensor 42 is exposed to flammable
vapor 40, the resistance of the chemiresistor sensor 42 changes,
indicating the presence of flammable vapor 40. Exemplary vapor
sensor circuits and resistive vapor sensor elements are disclosed
in U.S. Pat. No. 7,112,304, entitled "Robust Chemiresistor Sensor,"
and U.S. patent application Ser. No. 11/286,985, filed Nov. 23,
2005, entitled "Temperature Compensated Vapor Sensor," both
assigned to the assignee of the present application, Therm-O-Disc,
Incorporated, the contents of which are incorporated herein by
reference in their entirety.
[0020] The thermocouple 28 is disposed adjacent to a pilot flame.
When the thermocouple 28 is heated by the pilot flame, a voltage is
created across the output terminals 30 of the thermocouple 28. The
output terminals 30 of the thermocouple 28 are connected to the
flammable vapor sensor module 24 so that the thermocouple 28
provides an input to the flammable vapor sensor module 24. The
flammable vapor sensor module 24 may include a flammable vapor
sensor circuit (not shown), which is connected in series or
parallel with the power module 22. The flammable vapor sensor
module 24 receives the voltage input from the power module 22 and
applies a voltage output to the gas valve module 26. When the
voltage is applied to the gas valve module 26, the gas valve 32 of
the gas valve module 26 is energized to an open position and allows
the fuel gas to flow from a gas source (not shown) to the heating
appliance 10.
[0021] When the chemiresistor sensor 42 is exposed to flammable
vapor, the resistance of the chemiresistor sensor 42 increases or
decreases depending on the type of sensor and its application. As
the resistance changes to a value corresponding to a threshold
concentration of the flammable vapor 40, this changed resistance
causes interruption of the power applied to the gas valve module
26, thereby de-energizing the gas valve 32, causing it to close and
discontinue the flow of fuel gas to the burner 14. By discontinuing
fuel gas to the burner 14, the burner 14 of the heating appliance
10 cannot serve as a possible ignition source for the flammable
vapor 40. The operation of the gas-fired heating appliance 10 can
be restored, for example, after the flammable vapor sensor module
24 is replaced or the control device 20 is otherwise serviced.
[0022] An exemplary operation of such flammable vapor sensor is
disclosed in U.S. Pat. No. 7,112,059, entitled "Apparatus and
Method for Shutting Down Fuel Fired Appliance", the content of
which is incorporated herein by reference in its entirety.
[0023] It should be appreciated that a vapor sensor control circuit
assembly may be modified from that described, above, to accommodate
a capacitive vapor sensor element such as that disclosed in U.S.
patent application Ser. No. 11/297,752, filed Dec. 8, 2005 and
entitled "Capacitive Vapor Sensor." This patent application is
assigned to the assignee of the present application, Therm-O-Disc,
Incorporated. The contents of this application are incorporated
herein by reference in their entirety.
[0024] Because the output terminals 30 of the thermocouple 28 are
connected to the flammable vapor sensor module 24, an end user
cannot easily circumvent the flammable vapor sensor module 24. If
the end user attempts to short-circuit the flammable vapor sensor
module 24, the output voltage of the thermocouple 28 cannot be
applied to the gas valve module 26 and no fuel gas can be supplied
to the burner 14 in the absence of the flammable vapor sensor
module 24. Accordingly, the flammable vapor sensor control device
20 of the present disclosure resists tampering to promote a safe
operation of a gas-fired heating appliance 10.
[0025] This description 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 disclosure. Such variations
are not to be regarded as a departure from the spirit and scope of
the invention.
* * * * *