Electronic Gas/Air Burner Modulating Control

Abstract

An electronic control system for a power burner system for use with a heating appliance includes a burner tube, a gas valve for providing gas to the burner tube, an electronic control and a variable speed combustion air blower for mixing air with the gas provided to the burner tube. The electronic control system further includes a control in communication with the gas valve and the combustion air blower. The control may also be in communication with various other devices of an appliance, such as a variable speed air-circulating fan, a variable speed exhaust fan, or various sensors associated with the heating appliance. The control modulates the gas valve and the combustion air blower to maintain substantially stoichiometric conditions of the gas and air provided to the burner tube and as a function of signals from at least one of the devices. In one embodiment, the burner system may be used in a conveyor oven.

What is claimed is: 
     
         1 . A method of operating an electronic control system to modulate an air/gas rate and air/gas ratio of a burner comprising:
 providing a burner having a maximum heat output;   providing a modulating gas valve upstream from the burner, wherein the gas valve has an adjustable position, wherein the position of the gas valve and gas flow are capable of being adjusted based on a variable electronic signal;   providing a combustion air blower fan in communication with the burner that is capable of operating at a speed having a range of revolutions per minute and that is capable of being adjusted based on a variable electronic signal;   providing an electronic control that receives an input signal from a thermostat control and outputs a variable electronic signal to the modulating gas valve and to the combustion air blower fan, wherein the electronic control comprises a processor, a memory and a software application stored within the memory, wherein voltage values for operating the gas valve and voltage values for operating the combustion air blower are stored in the memory, and wherein the thermostat control is either integrated with and is a component of the electronic control or is a separate component from the electronic control,   adjusting the maximum heat output of the burner by:
 inputting a heat demand into the thermostat control; 
 inputting the heat demand from the thermostat control into the electronic control; 
 sending a signal from the electronic control to the gas valve and a return signal from the gas valve to the electronic control to verify the position of the gas valve; 
 verifying and adjusting a position of the gas valve as necessary by sending a signal from the electronic control to the gas valve; 
 sending a return signal from the gas valve to the electronic control indicating a new position of the gas valve; 
 processing the return signal received from the gas valve with the electronic control to verify that the adjusted gas valve position is correct; 
 upon verifying that the adjusted gas valve position is correct, sending a signal from the electronic control to the combustion air blower and a return signal from the combustion air blower to the electronic control to verify the speed of the combustion air blower and to determine whether a stall condition has occurred (blower speed is zero); 
 verifying and adjusting the speed of the combustion air blower as necessary by sending a signal from the electronic control to the combustion air blower; 
 sending a return signal from the combustion air blower to the electronic control indicating a new speed of the combustion air blower; 
 determining with the processor of the electronic control whether a value of voltage required to attain a desired combustion air blower speed is different from the combustion air blower voltage value stored in the memory of the electronic control for a desired speed to achieve maximum heat output; and, 
 storing a new voltage value in the memory corresponding to the speed of the combustion air blower if the voltage value for operating the combustion air blower at the desired speed to achieve maximum heat output has changed. 
   
     
     
         2 . The method of  claim 1 , wherein the thermostat is in electronic communication with the electronic control and the electronic control is in electronic communication with the gas valve and the combustion air blower. 
     
     
         3 . The method of  claim 2 , wherein the software application comprises an executable gas valve signal equation and an executable combustion air blower fan equation for determining the position of the gas valve and the speed of the combustion air blower respectively required to achieve an optimal heat output of the burner at a particular heat demand setting. 
     
     
         4 . The method of  claim 3 , wherein the gas valve signal equation comprises:
     GVS= 4.01(Tstat)+13.9   wherein GVS=a signal to the gas valve in pulse-width modulation (pwm),   wherein Tstat=a signal from the thermostat between 4 to 20 milliamps or between from about 4 to about 20 milliamps.   
     
     
         5 . The method of  claim 3 , wherein the combustion air blower fan equation comprises:
     RPM (Revolutions Per Minute)=2.7 x   3 −118.3 x   2 +1751.3 x− 2182.7;
   wherein x=a signal from the thermostat comprising 4 to 20 milliamps or about 4 to about 20 milliamps.   
     
     
         6 . The method of  claim 3 , wherein the electronic control system does not include an air shutter which is operated to restrict or increase the amount of air provided by the combustion air blower. 
     
     
         7 . The method of  claim 6 , wherein the combustion air blower fan equation comprises:
     RPM (Revolutions Per Minute)= R   m (2.7 x   3 −118.3 x   2 +1751.3 x− 2182.7);
   wherein R m =Rate multiplier for different heating rates, and   wherein x=a signal from the thermostat comprising 4 to 20 milliamps or about 4 to about 20 milliamps.   
     
     
         8 . The method of  claim 3 , wherein the electronic control system includes an air shutter which is operated to restrict or increase the amount of air provided by the combustion air blower. 
     
     
         9 . The method of  claim 8 , wherein the combustion air blower fan equation comprises:
     RPM=AS×R   m ×(2.7 x   3 −118.3 x   2 +1751.3 x− 2182.7);
   wherein R m =Rate multiplier, and   wherein AS=Air Shutter multiplier.   
     
     
         10 . The method of  claim 3 , wherein the electronic control senses a stall condition in the combustion air blower when a low voltage is directed to the combustion air blower in response to a given heat demand. 
     
     
         11 . The method of  claim 10 , wherein the electronic control stores a voltage value associated with the stall condition in the memory, wherein the electronic control avoids operating the combustion air blower below the voltage value associated with the stall condition during operation of the burner system and wherein the electronic control increases the voltage to the combustion air blower as necessary to overcome the stall condition. 
     
     
         12 . The method of  claim 1 , wherein the electronic control constantly monitors the speed of the combustion air blower by receiving signals from a speed sensor, wherein the electronic control adjusts the position of the gas valve between a first and second position, wherein the second position of the gas valve tracks a gradual reduction in speed of the combustion air blower to maintain substantially stoichiometric conditions as the electronic control system adjusts the burner to a lower heat output condition. 
     
     
         13 . The method of  claim 12 , wherein the electronic control rapidly moves the gas valve from the first position to the second position when the gas valve is within a particular range of the desired second position to avoid a delay in obtaining a desired heat rate and an overshoot of the desired lower heat output condition. 
     
     
         14 . The method of  claim 1 , wherein the electronic control system comprises an electronic display. 
     
     
         15 . The method of  claim 14 , wherein the electronic display comprises a 4-digit, 7-segment display that provides information regarding the burner status, including gas type, gas firing rate, air shutter position if applicable, revolutions per minute of the combustion air blower fan, gas valve position and flame signal. 
     
     
         16 . The method of  claim 15 , wherein the 4-digit, 7-segment display of the electronic control is in communication with an operable switch that allows adjustment of program settings for the gas type, gas firing rate, air shutter position setting if applicable, combustion air blower fan revolutions per minute, gas valve position and flame signal on the 4-digit, 7-segment display of the electronic control. 
     
     
         17 . The method of  claim 1 , wherein the electronic control comprises a serial port or a wireless communication port which allows for burner system to send and receive communications with other electronic devices or smart devices. 
     
     
         18 . The method of  claim 17 , wherein the serial port allows for operation and adjustment of operating settings of the burner system with a touchscreen thermostatic control. 
     
     
         19 . The method of  claim 18 , wherein the wireless communication port allows for operation and adjustment of operating settings of the burner system with smart devices such as a portable touchscreen thermostatic control, a portable computing device such as a smartphone, tablet or other mobile device or any other type of smart device. 
     
     
         20 . The method of  claim 1 , wherein the method is applied in different types of heating appliances.