Combustion – Timer – programmer – retarder or condition responsive control – Of or by exhaust damper or exhaust pump
Reexamination Certificate
2000-03-22
2001-07-10
Clarke, Sara (Department: 3743)
Combustion
Timer, programmer, retarder or condition responsive control
Of or by exhaust damper or exhaust pump
C431S080000
Reexamination Certificate
active
06257871
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to gas-fired appliances such as water heaters, space heaters and fireplaces and, more particularly, to a device for controlling components commonly found in gas-fired appliances, namely, dampers and valves.
2. Disclosure of Related Art
In a conventional gas-fired appliance a gas pipe delivers a fuel gas, such as natural gas, from a fuel source to both a pilot burner and to a main burner that are disposed proximate, or within, a combustion chamber. The gas pipe includes a pair of valves disposed within the gas pipe. The first valve controls the flow of fuel gas from the fuel source to the pilot burner. The second valve controls the flow of fuel gas to the main burner.
The pilot burner is provided to ignite fuel gas entering the main burner and may comprise a standing pilot burner or an intermittent pilot burner. If the pilot flame is extinguished for any reason, the valve between the fuel source and the pilot burner must be closed to prevent a buildup of gas within the appliance and the possibility of a fire or an explosion. As a result, conventional gas-fired appliances typically include a safety mechanism that detects the presence of the pilot flame and closes the valve between the fuel source and the pilot burner if the pilot flame is extinguished. One conventional safety mechanism incorporates a thermopile disposed proximate the pilot burner. The thermopile generates an electrical current in the presence of the pilot flame and the current is used to control the opening and closing of the valve between the fuel source and the pilot burner.
Conventional gas-fired appliances also typically include an exhaust vent or flue to direct emissions resulting from combustion away from the combustion chamber and into an area, such as the outdoors, where the emissions can dissipate. Exhaust vents, however, also allow heat to escape from the appliance thereby reducing the efficiency of the appliance. As a result, conventional gas-fired appliances typically include dampers disposed within the exhaust vent. The damper opens prior to ignition of the main burner to allow emissions from combustion to be evacuated from the appliance. When the main burner is extinguished, the damper closes to trap the remaining heat.
Conventional gas-fired appliances suffer from several drawbacks. The use of dampers and other electrically-actuated components within conventional appliances has often necessitated connecting the appliance to an external power source such as an A.C. power line. For example, many conventional appliances use a motor to open and close the damper wherein the motor is powered by an external power source. As a result, conventional appliances require additional components, are relatively expensive, and are dependent upon external electrical power even when sufficient fuel gas is present for operation of the appliance.
There is thus a need for a device for controlling a gasfired appliance that will minimize or eliminate one or more of the above-mentioned deficiencies.
SUMMARY OF THE INVENTION
The present invention provides a device for controlling a gas-fired appliance such as a water heater, space heater, or fireplace. In particular, the present invention provides a device for controlling the damper and the main burner valve in a gas-fired appliance by using current generated by a thermoelectric device within the appliance. The thermoelectric device may comprise a thermopile disposed proximate a pilot burner in the appliance.
A device in accordance with the present invention for controlling a damper and a main burner valve in a gas-fired appliance having a thermoelectric device includes several elements. First, the inventive device includes a motor having a shaft extending therefrom for connection to a plate of the damper. Second, the device includes a control circuit for selectively transmitting current generated by the thermoelectric device to the motor and to the main burner valve. The control circuit may include a temperature sensor and a plurality of switches that direct current to the motor and the main burner valve. When the temperature sensor determines that the temperature of a medium such as water or air is below a predetermined temperature, current may be directed through the switches to the motor. The motor uses the current to move the plate in the damper from a first position to a second position. The first and second positions preferably correspond to closed and open positions of the damper. Once the plate has reached the second position and the damper is open, current may be redirected through the switches to the main burner valve to open the valve and allow the introduction of fuel gas to the main burner. When the predetermined temperature is reached, current may again be directed through the switches to the motor thereby allowing the valve to close. The motor may use the current to move the plate of the damper from the second or open position to the first position or closed position to trap remaining heat within the appliance.
A device in accordance with the present invention represents a significant improvement as compared to conventional control systems for gas-fired appliances. In particular, the inventive control device derives its energy entirely from the appliance (i.e., is self-powered) and does not require a battery or external power source. As a result, a gas-fired appliance incorporating the inventive control device requires fewer components, is less expensive, and is not dependent upon external power for operation.
These and other features and objects of this invention will become apparent to one skilled in the art from the following detailed description and the accompanying drawings illustrating features of this invention by way of example.
REFERENCES:
patent: 2349443 (1944-05-01), McCarty
patent: 4204833 (1980-05-01), Kmetz et al.
patent: 4406396 (1983-09-01), Habegger
patent: 4550874 (1985-11-01), Clouser et al.
patent: 4778378 (1988-10-01), Dolnick et al.
patent: 4846400 (1989-07-01), Crouse
patent: 5393221 (1995-02-01), McNally
Droll Paul W.
Weiss Cory A.
Clarke Sara
Dykema Gossett PLLC
Effikal International, Inc.
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