Fluid handling – Self-proportioning or correlating systems – Mixture condition maintaining or sensing
Reexamination Certificate
2000-02-28
2003-06-03
Walton, George L. (Department: 3753)
Fluid handling
Self-proportioning or correlating systems
Mixture condition maintaining or sensing
C137S004000, C137S006000, C137S009000, C137S087010, C137S101190, C137S487500, C431S012000, C431S019000, C431S075000, C431S089000
Reexamination Certificate
active
06571817
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to gas valves used in fuel burning appliances. More specifically, the present invention relates to a gas valve which safely operates by insuring that combustion air is present before gas is provided to the combustion chamber.
In fuel burning heating systems, gas valves are typically used to control the flow of fuel into a combustion chamber. Several different control methods have been used for operating this gas valve. Generally speaking, the gas valve is operationally attached to a thermostat. When the thermostat calls for heat, the gas valve is then actuated, providing gas to the combustion chamber. Other components of the heating system (blowers, vents, etc.) are also operated to cause the heating of air, which is thus provided at a furnace output.
As can be appreciated, it is essential that combustion air be present in order to allow burning of the combustion fuel. If combustion air is not present, and the gas valve is opened, a potentially dangerous situation is created.
One method for insuring that combustion air is present in the combustion chamber includes the use of a pressure switch which is operationally coupled to the combustion chamber. More specifically, a pressure switch is attached such that its input is connected to the combustion chamber. Thus, when the pressure is above a predetermined level, this pressure switch is closed. This switch can then be used as a safety system for the furnace. More specifically, the furnace will not be allowed to operate unless this pressure switch is closed.
Unfortunately, typical pressure switches utilized in this fashion are large and cumbersome. These pressure switches are typically a pancake type pressure switch which is typically configured in a disk shaped format, about three inches in diameter. These pressure switches take up space and are not easily integrated into heating systems. Also, this switch provides only an on/off type output. Thus, the switches do not provide any additional information which may prove useful in the operation of the furnace. Additionally, the pressure level at which the switch closes cannot be adjusted after the switch has been installed. Consequently, this type of pressure sensor has many drawbacks and is not the most beneficial device to use.
SUMMARY OF THE INVENTION
The present invention provides an integrated solution which safely and efficiently operates a gas valve for a combustion furnace. In addition to the typical functions of a gas valve (i.e., control of fuel to a combustion chamber), the valve includes an integrated combustion air sensor for monitoring combustion air. The output from the sensor is provided to a controller which will not allow the valve and/or furnace to operate when combustion air is not present.
All components of the pressure proving gas valve are contained in a single housing. These components include the valve element, the controller, and combustion air sensor, and all necessary inlet and outlet ports. More specifically, the housing includes a fuel inlet port, a fuel outlet port and an air flow inlet port. The fuel inlet port and the fuel outlet port are on opposite sides of the valve element, thus controlling the flow of combustion fuel therethrough. Similarly, the airflow inlet port is in communication with the combustion air sensor, to allow its efficient operation. In addition to these inlets, all necessary electrical connections are provided through openings in the housing. These electrical connections include those necessary to communicate with the controller. Further, connections to an external thermostat are provided, thus allowing the basic function of the valve.
By including the combustion air sensor within the valve housing itself, additional functionality and wiring simplicity is also provided. Typically, a fan or blower of some type is associated with the furnace. This fan could thus be connected to the controller to regulate airflow as necessary. Thus, in addition to sensing the presence of airflow, the airflow itself could be specifically controlled. Specific air to gas ratios can then be achieved in the combustion process. Without the airflow sensor within the gas valve, this overall functionality is difficult and costly to achieve.
It is an object of the present invention to provide additional safety functions to a gas valve by insuring airflow is present. Thus, gas will not be provided to the combustion chamber without airflow also being present, thus avoiding potentially dangerous situations.
It is an additional object of the present invention to provide an integrated solution and additional functionality to the gas valve by coordinating multiple operations. As is well understood, a valve can be controlled to efficiently run the gas-burning portion of the furnace itself. However, by being able to monitor and control airflow through the furnace, in addition to gas flow, multiple operating conditions can be achieved. For example, very specific fuel air ratios can be maintained in the combustion chamber for whatever purpose is necessary.
The present invention further provides an additional safety feature by sensing and indicating that the combustion path is blocked or someway restricted. For example, should the exhaust pathway be blocked somehow, the valve of the present invention would recognize that and shut off.
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Honeywell International , Inc.
Walton George L.
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