BACKGROUND OF THE INVENTION
1. Field of the Invention.
The present invention relates to a system for controlling the flow and combustion of natural gas and/or liquid propane in a fireplace or heater burner apparatus.
2. Description of the Related Art.
Fireplaces have been utilized by homeowners for decades to heat the interior of their home and/or to enhance the aesthetic beauty of their home. Numerous types of fireplaces exist. Natural wood burning fireplaces are common and require a chimney to vent the combustion byproducts, including carbon monoxide gas and particulate matter, outside of the living quarters of the home. Additionally, natural wood fireplaces require the homeowner to procure wood and physically place the wood within the fireplace for combustion. In contrast, natural gas and liquid propane fireplaces eliminate the need to procure wood. Additionally, these fireplaces recreate the appearance of a natural wood fire by combusting the gas at the surface of a burner. Moreover, due to the clean burning properties of natural gas and liquid propane, these fireplaces can be designed so that they are vented directly into the room, known as ventless fireplaces, increasing their efficiency and avoiding the need for a flue.
All fireplaces, regardless of the design utilized therein, consume oxygen during combustion. With natural gas and liquid propane ventless fireplaces, the combustion of the gas consumes oxygen which may cause the supply of oxygen within the home to be reduced and the levels of carbon monoxide and carbon dioxide gas to correspondingly increase. To prevent the levels of carbon monoxide and carbon dioxide gases within the home from reaching elevated levels, oxygen depletion sensors can be incorporated into the fireplace design.
- SUMMARY OF THE INVENTION
During normal operation of a ventless gas fireplace, the gas is piped to a pilot, i.e. a small exit for gas within the fireplace, where it is ignited. The resulting pilot flame is then allowed to burn uninterrupted. To provide gas to the burner, a thermocouple is placed near the pilot flame and, once sufficiently heated, it produces an electrical current which keeps the pilot valve open and signals an electronic control module and/or a gas control valve to start the flow of gas to the burner. The pilot flame then ignites the gas as it exits the burner. As the fire burns within the fireplace, the oxygen depletion sensor monitors the level of oxygen therein. If the level of oxygen in the air falls below a preset threshold, the pilot will become unstable and flicker. The absence of a pilot flame in contact with the thermocouple causes the thermocouple to cool and, resultantly, the flow of electricity from the thermocouple to fall or cease. The decrease or cessation in electrical output is detected by the electronic control module or gas control valve which halts the flow of gas to both the main burner and the pilot light.
BRIEF DESCRIPTION OF THE DRAWING
The present invention provides a system for controlling the flow and combustion of natural gas and/or liquid propane in a fireplace or heater burner apparatus. In one embodiment, the system utilizes an oxygen depletion sensor pilot in combination with a burner, an electronic control module, a gas control valve, an igniter, and a flame rectification sensor. The flame rectification sensor utilizes an ionized flame to rectify the electrical current sent through the sensor. When the pilot is lit, an ionized flame is provided and the current of the flame rectification sensor is rectified. The flame rectification sensor then provides the rectified current to the electronic control module to initiate the delivery of gas to the main burner via the gas control valve where it is ignited by the pilot flame. When the oxygen level within the fireplace falls below a predetermined level, the flame at the pilot becomes unstable. This prevents the rectification of current at the flame rectification sensor, signaling the electronic control module to cease the flow of gas to the burner and pilot via the gas control valve.
The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention itself will be better understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawing, wherein:
FIG. 1 is schematic of the gas flow and combustion system of the present invention.
- DETAILED DESCRIPTION OF THE INVENTION
The exemplification set out herein illustrates one preferred embodiment of the invention, in one form, and such exemplification is not to be construed as limiting the scope of the invention any manner.
FIG. 1 depicts gas flow and combustion control system 10. While system 10 is described herein with specific reference to a ventless gas fireplace, system 10 can be reconfigured and utilized in other applications. With reference to FIG. 1, system 10 includes electronic control module 12, gas control valve 14, burner 16, oxygen depletion sensor (“ODS”) pilot 18 having a ruby orifice (not shown), igniter 20, and flame rectification sensor 22.
To control the operation of system 10, electronic control module 12 sends and receives signals from the various components of system 10, as described below. An example of the electronic control module which may be utilized in the present system is the electronic control module available from American Flame, Fort Wayne, Ind., series number AF-4000 MOD. Electronic control module 12 can be powered by a battery, such as a six-volt battery (not shown), connected thereto or can be configured for connection to a source of A/C power. Electronic control module 12 sends an electrical signal to gas control valve 14 through wires 24, 26. Wire 24 is connected to gas control valve 14 and signals gas control valve 14 to start or stop the flow of gas to burner 16. Wire 26 is connected to gas control valve 14 and signals gas control valve 14 to start or stop the flow of gas to ODS pilot 18.
Additionally, electronic control module 12 also sends an electrical current to igniter 20 via wire 28. This current causes tip 30 of igniter 20 to emit a spark. The spark from igniter 20 will ignite ODS pilot 18 when gas is flowing therethrough. Furthermore, electronic control module 12 receives a signal from flame rectification sensor 22, as discussed below. Finally, electronic control module 12 receives electronic input from receiver 32 via wire 34. The input sent from receiver 32 instructs electronic control module 12 to perform a specified action, i.e. start or stop gas flow and/or ignite ODS pilot 18. Receiver 32 can be designed to receive input from an external infrared or radio signal remote control unit, as well as from other known controllers.
Gas control valve 14 is connected at inlet 36 to gas supply line 38, such as a natural gas grid or a liquid propane tank (not shown). An example of the gas control valve which may be utilized in the present system is a spark to pilot electronic valve available from American Flame, Fort Wayne, Ind., series number AF-4000. As described in detail below, when gas control valve 14 is in a position corresponding to an ON condition, gas flows to both burner 16 and ODS pilot 18 via outlets 40, 42 and pipes 44, 46 respectively. Similarly, when gas control valve 14 is in a position corresponding to an OFF condition, the flow of gas from supply line 38 to pipes 44, 46, and correspondingly burner 16 and ODS pilot 18, is prevented. Finally, when gas control valve 14 is in a position corresponding to a PILOT ON condition, the flow of gas from supply line 38 through pipe 46 and ODS pilot 18 is allowed, while the flow of gas through pipe 44 and, correspondingly, burner 16 is prevented.
To ignite burner 16, i.e. turn on the fireplace, a signal is sent to receiver 32 which transmits an electrical input to electronic control module 12 instructing electronic control module 12 to ignite burner 16. Electronic control module 12 then sends a signal to gas control valve 14 via wire 26. In response, gas control valve 14 is oriented in a PILOT ON position and gas flows from gas supply line 38 through gas control valve 14 and pipe 46 to ODS pilot 18, mounted on L-shaped bracket 48. Substantially immediately thereafter, electronic control module 12 provides electric current to igniter 20, which is mounted on L-shaped bracket 48 at a right angle to ODS pilot 18, via wire 28. The current creates a spark at tip 30 of igniter 20, as described above, sufficient to ignite the gas escaping from end 50 of ODS pilot 18.
ODS pilot 18 will stay lit due to the continual flow of gas from gas supply line 38, as described above. Flame rectification sensor 22, which is commercially available from Johnson Controls or White-Rodgers, for example, is positioned near ODS pilot 18 on L-shaped bracket 48 so that the electrode 54 of flame rectification sensor 22 is at least partially within the flame of ODS pilot 18 when ODS pilot 18 is ignited. A current is sent to electrode 54 and, when the electrode is within an ionized flame, the current is rectified. In response to the rectified signal from flame rectification sensor 22, electronic control module 12 sends a signal to gas control valve 14 via wire 24. This signal positions gas control valve 14 in an ON condition and allows for the flow of gas from gas supply line 38 via gas control valve 14 and pipes 44, 46 to both burner 16 and ODS pilot 18, respectively. As gas escapes apertures 56 of burner 16, it is ignited by the flame at previously ignited ODS pilot 18.
To stop the flow of gas to burner 16 and ODS pilot 18, i.e., turn off the fireplace, a signal is sent to receiver 32 which transmits an electrical input to electronic control module 12 via wire 34 instructing electronic control module 12 to extinguish burner 16 and ODS pilot 18. In response, electronic control module 12 sends a signal to gas control valve 14 via wires 24, 26. The gas control valve 14 is now positioned in an OFF condition and the flow of gas from gas supply line 38 to both pipes 44, 46, and correspondingly burner 16 and ODS pilot 18, respectively, is prevented. With no additional supply of gas, the flames at ODS pilot 18 and burner 16 are extinguished.
Additionally, system 10 will automatically stop the flow of gas to ODS pilot 18 and burner 16 if the level of oxygen in the air drops below a predetermined level. As the oxygen in the air around ODS pilot 18 falls, the flame generated at ODS pilot 18 will become unstable and flicker and, if the oxygen is sufficiently depleted, this will be sensed by the flame rectification sensor and the current is no longer rectified. The absence of a rectified signal is detected by electronic control module 12 and electronic control module 12 sends a signal to gas control valve 14 via wires 24, 26. This signal causes gas control valve 14 to be placed in an OFF condition, preventing the flow of gas to burner 16 and ODS pilot 18. Once the level of oxygen has increased above the cutoff level of ODS pilot 18, system 10 can be reactivated and burner 16 can be ignited as described above.
While this invention has been described as having a preferred design, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.