초록 ▼

An apparatus is provided for controlling the operation of a gas fired appliance having a gas valve circuit for enabling the flow of gas to the burner. The apparatus comprises a sensor capable of detecting the presence of flammable vapor, a switching means in series with the gas valve solenoid circui

An apparatus is provided for controlling the operation of a gas fired appliance having a gas valve circuit for enabling the flow of gas to the burner. The apparatus comprises a sensor capable of detecting the presence of flammable vapor, a switching means in series with the gas valve solenoid circuit for interrupting a thermocouple voltage to the gas valve solenoid to disable the flow of gas, and a fuse that normally conducts a current to the switching means to maintain the switching means in a conductive state for applying a thermocouple voltage to the gas valve solenoid. In response to the detection by the sensor of the presence of a predetermined level of flammable vapor concentration, a second switch supplies a higher current through the fuse. The higher current causes the fuse to blow and interrupt the current for maintaining the switching means in a conductive state, such that the switching means interrupts the thermocouple voltage applied to the gas valve solenoid to shut off the gas to the burner.

대표청구항 ▼

What is claimed is: 1. A control for operating a thermocouple-powered solenoid actuated gas valve, the control comprising: a first switch having open and closed states, and which when in the closed state provides power from the thermocouple to the solenoid; a power lead for providing power to the

What is claimed is: 1. A control for operating a thermocouple-powered solenoid actuated gas valve, the control comprising: a first switch having open and closed states, and which when in the closed state provides power from the thermocouple to the solenoid; a power lead for providing power to the first switch to keep the first switch in the closed state, the power lead having a fuse therein, which when triggered interrupts power to the first switch; a flammable gas sensor for sensing flammable gas; and a second switch, responsive to the flammable gas sensor, for providing power to trigger the fuse to interrupt power to the first switch, causing the first switch to close and interrupt power to the solenoid, thereby closing the gas valve. 2. An apparatus for controlling the operation of a fuel-fired appliance burner having a gas valve solenoid circuit for enabling the flow of gas to the burner, comprising: a sensor capable of detecting the presence of flammable vapor; a first switch in series with the gas valve solenoid circuit for interrupting a thermocouple voltage to the gas valve solenoid to disable the flow of gas; a fuse that normally conducts a current to the first switch to maintain the first switch in a conductive state for applying a thermocouple voltage to the gas valve solenoid; a second switch that responds to detection by the sensor of the presence of a predetermined level of flammable vapor concentration, by supplying a current through the fuse sufficient to interrupt the current for maintaining the first switch means in a conductive state, such that the first switch interrupts the thermocouple voltage applied to the gas valve solenoid to shut off gas to the burner. 3. The apparatus of claim 2 wherein the resistance of the sensor resistance increases as the concentration of flammable vapors increases. 4. The apparatus of claim 3 wherein the sensor is incorporated in a voltage divider circuit that comprises a resistor in series with the sensor, and an increase in resistance of the sensor will yield a voltage potential from the voltage divider that switches on the second switch. 5. The apparatus of claim 4 wherein the second switch is a field effect transistor. 6. The apparatus of claim 5 wherein the second switch switches on to conduct a high current through the fuse causing the fuse to blow when the sensor incorporated in the voltage divider circuit detects a predetermined flammable vapor concentration. 7. The apparatus of claim 4 wherein the predetermined flammable vapor concentration is about 50 percent of the lower flammability level. 8. The apparatus of claim 6 further comprising a battery for supplying voltage to the voltage divider circuit and the current switched to the fuse. 9. The apparatus of claim 8 further comprising means for shutting down the appliance burner circuit when the battery voltage level is below a predetermined value. 10. The apparatus of claim 9 further comprising an audible alarm for alerting the occupant when the sensor detects the predetermined flammable vapor concentration. 11. A control circuit for shutting off a fuel-fired appliance burner having a thermocouple voltage that enables a gas valve solenoid to supply fuel to the appliance burner, the control circuit comprising: a power source for powering the control circuit, a first switch that is connected in series with the gas valve solenoid of the appliance in a manner such that the thermocouple current to the gas valve solenoid is interrupted when the first switch opens to cause the flow of gas to the burner to be shut off; a sensor capable of detecting the presence of flammable vapor, the sensor responsively changing in resistance as the concentration of flammable vapor changes; a fuse that normally conducts current from the power source to the first switch to maintain a conductive state of the first switch for supplying thermocouple current to the gas valve solenoid; a second switch, which, responsive to detection by the sensor of the presence of a predetermined level of flammable vapor concentration, supplies a higher current through the fuse which opens to interrupt the current for maintaining the first switch in a conductive state, such that the first switch interrupts the thermocouple voltage applied to the gas valve solenoid to shut off the gas to the burner; and a voltage divider circuit including a resistor and the sensor, wherein the detection of a predetermined level of flammable vapors by the sensor causes the voltage potential between the resistor and the sensor to activate the second switch for switching a current from the power source through the fuse sufficient to open the fuse to interrupt current for maintaining the first switch in a conductive state, such that the flow of gas to the burner is shut-off. 12. The control circuit of claim 11 wherein the resistance of the sensor increases as the concentration of flammable vapor increases. 13. The apparatus of claim 12 wherein the second switch shorts a resistor to establish a higher current through the fuse that will cause the fuse to open. 14. The control circuit of claim 13 wherein an increase in resistance of the sensor will yield a voltage potential from the voltage divider circuit that switches on the second switch when the sensor detects a predetermined flammable vapor concentration that is about 50 percent of the lower flammability level. 15. The control circuit of claim 14 wherein the power source comprises at least one battery. 16. The control circuit of claim 15 further comprising a means for shutting down the appliance burner circuit when the battery voltage level is below a predetermined value. 17. A control circuit in connection with a thermocouple voltage source that powers a solenoid in a gas valve circuit of an appliance, for shutting off the flow of gas to discontinue operation of the appliance burner, the control circuit comprising: a power source for powering the control circuit, a first switch that is connected in series with the gas valve solenoid of the appliance in a manner such that the thermocouple current to the gas valve solenoid is interrupted when the first switch opens to cause the flow of gas to the burner to be shut off; a first sensor capable of detecting the presence of a predetermined level of flammable vapors, the first sensor responsively increasing in resistance as the concentration of flammable vapors increases; a second sensor capable of detecting the presence of a second vapor, where the second sensor responsively decreases in resistance as the concentration of second vapor increases; a fuse that normally conducts current from the power source to the first switch to maintain a conductive state of the first switch for supplying thermocouple current to the gas valve solenoid; a second switch, which in response to the first and second sensors detection of the presence of a predetermined level of a first or second vapor concentration, switches a current through the fuse which opens the fuse and interrupts the current for maintaining the first switch in a conductive state, such that the first switch interrupts the thermocouple voltage applied to the gas valve solenoid to shut off the gas to the burner; and a voltage divider circuit incorporating the first sensor and the second sensor, so that the detection of a predetermined level of flammable vapors by the first sensor or the detection of a predetermined level of a second vapor by the second sensor yields a voltage potential between the first sensor and the second sensor that activates the second switch device for switching a current from the power source through the fuse that will open the fuse to interrupt current to the first switching means to cause the flow of gas to the burner to be shut-off. 18. The control circuit of claim 17 wherein the first sensor's resistance increases as the concentration of flammable vapor increases. 19. The control circuit of claim 18 wherein the voltage potential of the voltage divider circuit switches the single second switch on when the first sensor detects a predetermined flammable vapor concentration of about 50 percent of the lower flammability level. 20. The control circuit of claim 19 wherein the second sensor is capable of detecting carbon monoxide gas, and the second sensor's resistance decreases as the concentration of carbon monoxide gas increases such that the voltage potential of the voltage divider circuit switches the single second switch on when the second sensor detects a predetermined carbon monoxide gas concentration. 21. The control circuit of claim 20 wherein the power source comprises at least one battery. 22. The control circuit of claim 21 further comprising a means for shutting down the appliance burner circuit when the battery voltage level is below a predetermined value.