Burner assembly for heating a screed plate of a paving machine

Abstract

A burner assembly for heating a screed plate of a screed assembly connected to a frame of a paving machine. The screed assembly includes a heating chamber adjacent to the screed plate. The burner assembly includes a blower that moves air into the heating chamber, and a fuel injection system including a fuel valve. The fuel injection system introduces fuel to the heating chamber. The burner assembly further includes an igniter that ignites the fuel to produce a flame, a thermocouple positioned within an expected flame path, and a controller. The thermocouple generates a thermocouple voltage having a relationship to a temperature surrounding a junction of the thermocouple, and the controller operates the fuel valve based in part on the thermocouple voltage.

What is claimed is:  
     
         1 . A burner assembly for heating a screed plate of a screed assembly connected to a frame of a paving machine, the screed assembly including a heating chamber adjacent to the screed plate, the burner assembly comprising: 
 a blower that moves air into the heating chamber;    a fuel injection system including a fuel valve, the fuel injection system introducing fuel to the heating chamber;    an igniter that ignites the fuel to produce a flame;    a thermocouple having a junction positioned within an expected flame path, the thermocouple generating a thermocouple voltage having a relationship to a temperature surrounding the junction; and    a controller connected to the thermocouple, the controller operating the fuel valve based in part on the thermocouple voltage.    
     
     
         2 . A burner assembly as set forth in  claim 1  wherein the burner assembly further comprises a signal converter that receives the thermocouple voltage, and generates a signal simulating an optical sensor signal, and wherein the controller operates the fuel valve based in part on the signal simulating the optical sensor signal.  
     
     
         3 . A burner assembly as set forth in  claim 1  wherein the burner assembly further comprises a signal converter that receives the thermocouple voltage and a current from the controller, and superimposes a signal produced by the thermocouple voltage on to the current, and wherein the controller operates the fuel valve based in part on the superimposed signal.  
     
     
         4 . A burner assembly as set forth in  claim 1  and wherein the controller further operates the blower based in part on the thermocouple voltage.  
     
     
         5 . A burner assembly as set forth in  claim 1  wherein the burner assembly further comprises a signal converter electrically connected between the thermocouple and the controller, and wherein the signal converter receives the thermocouple voltage, receives a current from the controller, and controls an amplitude of the current based in part on the received thermocouple voltage.  
     
     
         6 . A burner assembly as set forth in  claim 5  wherein the signal converter includes an amplifier having a first input pin that receives the thermocouple voltage, and a first power pin that receives the current from the controller.  
     
     
         7 . A burner assembly as set forth in  claim 6  wherein the signal converter further includes a first resistor, and a second resistor, wherein the amplifier further includes a second input pin, a second power pin, and an output pin, wherein a first end of the first resistor is connected to the second input pin, and the output terminal, wherein the second end of the first resistor is connected to a ground, wherein a first end of the second resistor is connected to the first input pin, and wherein a second end of the second resistor is connected to the ground.  
     
     
         8 . A burner assembly as set forth in  claim 5  wherein the burner assembly further comprises a second signal converter electrically connected between the first signal converter and the controller, wherein the second signal converter provides the current to the first signal converter, and produces a conditioned voltage having a relationship to the amplitude of the controlled current.  
     
     
         9 . A burner assembly as set forth in  claim 5  wherein the second signal converter includes 
 a resistor having first and second ends, the first end being connectable to a power source, and the second end being connected to the first signal converter,  
 a differential amplifier having a first input connected to the second end of the resistor, and a second input connected to a reference voltage, and  
 an amplifier connected to the differential amplifier.  
 
     
     
         10 . A burner assembly as set forth in  claim 5  wherein the controller includes 
 a second signal converter connected to the first signal converter, the second signal converter providing the current to the first signal conditioner and producing a conditioned voltage having a relationship to the amplitude of the controlled current, and  
 a processing unit connected to the second converter, the processor receiving the conditioned voltage, executing one or more software modules to analyze the conditioned voltage, and producing an output to control the fuel valve based in part on the analyzed conditioned voltage.  
 
     
     
         11 . A burner assembly as set forth in  claim 10  wherein the second signal converter includes 
 a resistor having first and second ends, the first end being connected to a power source, and the second end being connected to the first signal converter,  
 a differential amplifier having a first input connected to the second end of the resistor, and a second input connected to a reference voltage, and  
 an amplifier connected to the differential amplifier.  
 
     
     
         12 . A burner assembly as set forth in  claim 1 , a temperature sensor that senses a temperature of the heating chamber, and generates a chamber temperature signal, and wherein the controller further operates the fuel valve based in part on the chamber temperature signal.  
     
     
         13 . A burner assembly as set forth in  claim 12  wherein the controller further operates the blower based in part on the chamber temperature signal.  
     
     
         14 . A burner assembly as set forth in  claim 1  wherein the controller further comprises a signal conditioner that receives the thermocouple voltage, and produces a conditioned voltage having a scaled range, and wherein the controller operates the fuel valve based in part on the conditioned voltage.  
     
     
         15 . A paving machine comprising: 
 a frame;    a hopper connected to the frame;    a screed assembly connected to the frame, the screed assembly including a screed plate and a heating chamber adjacent to the screed plate; and    a blower that moves air into the heating chamber,    a fuel injection system including a fuel valve, the fuel injection system introducing fuel to the heating chamber,    an igniter that ignites the fuel to produce a flame,    a thermocouple having a junction positioned within an expected flame path, the thermocouple generating a thermocouple voltage having a relationship to a temperature surrounding the junction, and    a controller connected to the thermocouple, the controller operating the fuel valve based in part on the thermocouple voltage.    
     
     
         16 . A paving machine as set forth in  claim 15  wherein the paving machine further comprises a signal converter that receives the thermocouple voltage, and generates a signal simulating an optical sensor signal, and wherein the controller operates the fuel valve based in part on the signal simulating the optical sensor signal.  
     
     
         17 . A paving machine as set forth in  claim 15  wherein the paving machine further comprises a signal converter that receives the thermocouple voltage and a current from the controller, and superimposes a signal produced by the thermocouple voltage on to the current, and wherein the controller operates the fuel valve based in part on the superimposed signal.  
     
     
         18 . A paving machine as set forth in  claim 15  and wherein the controller further operates the blower based in part on the thermocouple voltage.  
     
     
         19 . A paving machine as set forth in  claim 15  wherein the paving machine further comprises a signal converter electrically connected between the thermocouple and the controller, and wherein the signal converter receives the thermocouple voltage, receives a current from the controller, and controls an amplitude of the current based in part on the received thermocouple voltage.  
     
     
         20 . A paving machine as set forth in  claim 19  wherein the signal converter includes an amplifier having a first input pin that receives the thermocouple voltage, and a first power pin that receives the current from the controller.  
     
     
         21 . A paving machine as set forth in  claim 20  wherein the signal converter further includes a first resistor, and a second resistor, wherein the amplifier further includes a second input pin, a second power pin, and an output pin, wherein a first end of the first resistor is connected to the second input pin, and the output terminal, wherein the second end of the first resistor is connected to a ground, wherein a first end of the second resistor is connected to the first input pin, and wherein a second end of the second resistor is connected to the ground.  
     
     
         22 . A paving machine as set forth in  claim 19  wherein the paving machine further comprises a second signal converter electrically connected between the first signal converter and the controller, wherein the second signal converter provides the current to the first signal converter, and produces a conditioned voltage having a relationship to the amplitude of the controlled current.  
     
     
         23 . A paving machine as set forth in  claim 24  wherein the second signal converter includes 
 a resistor having first and second ends, the first end being connectable to a power source, and the second end being connected to the first signal converter,  
 a differential amplifier having a first input connected to the second end of the resistor, and a second input connected to a reference voltage, and  
 an amplifier connected to the differential amplifier.  
 
     
     
         24 . A paving machine as set forth in  claim 19  wherein the controller includes 
 a second signal converter connected to the first signal converter, the second signal converter providing the current to the first signal conditioner and producing a conditioned voltage having a relationship to the amplitude of the controlled current, and  
 a processing unit connected to the second converter, the processor receiving the conditioned voltage, executing one or more software modules to analyze the conditioned voltage, and producing an output to control the fuel valve based in part on the analyzed conditioned voltage.  
 
     
     
         25 . A paving machine as set forth in  claim 24  wherein the second signal converter includes 
 a resistor having first and second ends, the first end being connected to a power source, and the second end being connected to the first signal converter,  
 a differential amplifier having a first input connected to the second end of the resistor, and a second input connected to a reference voltage, and  
 an amplifier connected to the differential amplifier.  
 
     
     
         26 . A paving machine as set forth in  claim 15 , a temperature sensor that senses a temperature of the heating chamber, and generates a chamber temperature signal, and wherein the controller further operates the fuel valve based in part on the chamber temperature signal.  
     
     
         27 . A paving machine as set forth in  claim 26  wherein the controller further operates the blower based in part on the chamber temperature signal.  
     
     
         28 . A burner assembly as set forth in  claim 15  wherein the controller further comprises a signal conditioner that receives the thermocouple voltage, and produces a conditioned voltage having a scaled range, and wherein the controller operates the fuel valve based in part on the conditioned voltage.  
     
     
         29 . A temperature sensing circuit connectable to a power source comprising: 
 a thermocouple that produces a thermocouple voltage; and    a signal converter that receives the thermocouple voltage and a current from the power source, and superimposes a signal created by the thermocouple voltage on to the current.    
     
     
         30 . A temperature sensing circuit as set forth in  claim 29  wherein the signal converter includes an amplifier having a first input pin that receives the thermocouple voltage, and a first power pin that receives the current, and wherein the amplifier controls the amplitude of the current with a relationship to the thermocouple voltage.  
     
     
         31 . A temperature sensing circuit as set forth in  claim 30  and further comprising a resistor having a first end connected to a power supply, and a second end connected to the amplifier at the first power pin, and wherein the resistor receives the current, and develops a first voltage at the second end.  
     
     
         32 . A temperature sensing circuit as set forth in  claim 31  wherein the amplifier further includes a second input pin, a second power pin, and an output pin, wherein the second power pin is connected to a ground, and wherein the temperature sensing circuit further comprises: 
 a second resistor having a first end connected to the output pin, and the second input pin, a second end connected to the ground; and  
 a third resistor including a first end connected to the first input pin and a second end connected to a ground.  
 
     
     
         33 . A temperature sensing circuit as set forth in  claim 32  and further comprising: 
 a capacitor having a first end connected to the first power pin and a second end connected to ground.  
 
     
     
         34 . A temperature sensing circuit as set forth in  claim 31  and further comprising: 
 a differential amplifier having a first input connected to the second end of the first resistor, and a second input connected to a reference voltage, the differential amplifier receiving the first voltage and producing a second voltage proportional to the difference between the first voltage and the reference voltage; and  
 an amplifier connected to the differential amplifier that produces a third voltage proportional to the second voltage.  
 
     
     
         35 . A temperature sensing circuit as set forth in  claim 34  and further comprising: 
 a processing unit connected to the amplifier, the processing unit being operable to receive the third voltage, and to execute one or more software modules for analyzing the third voltage.  
 
     
     
         36 . A method of controlling a burner assembly connected to a paving machine having a screed plate, the method comprising: 
 providing a thermocouple having a thermocouple junction;    positioning the thermocouple junction within an expected flame path;    opening a fuel valve to allow a fuel to flow through the valve;    igniting the fuel to produce a flame;    generating a signal functionally related to a temperature surrounding the thermocouple junction;    analyzing the thermocouple voltage; and    generating an output when the analyzed thermocouple voltage signifies a non-lit fuel condition.    
     
     
         37 . A method as set forth in  claim 36  and further comprising controllably heating the screed plate with the flame based in part on the analyzed thermocouple voltage.  
     
     
         38 . A method as set forth in  claim 36  wherein the generating a thermocouple voltage includes 
 providing an amplifier,  
 providing the thermocouple voltage to the amplifier,  
 providing a current to the amplifier,  
 controlling the amplitude of the current with the amplifier, the amplitude of the current being functionally related to the thermocouple voltage.  
 
     
     
         39 . A method as set forth in  claim 36  wherein analyzing the thermocouple voltage includes: 
 conditioning the thermocouple voltage to produce a conditioned voltage,  
 sampling the conditioned voltage to create a conditioned value,  
 providing a filtered value,  
 comparing the conditioned voltage to the filtered value,  
 increasing the filtered value when the conditioned value is greater than the filtered value,  
 decreasing the filtered value when the conditioned value is less than the filtered value.  
 
     
     
         40 . A method as set forth in  claim 39  wherein analyzing the thermocouple voltage further includes comparing the filtered value to a threshold value signifying a non-lit fuel condition.  
     
     
         41 . A method as set forth in  claim 39  wherein analyzing the thermocouple voltage further includes, when the conditioned value is greater than the filtered value, 
 setting a first flag,  
 incrementing a first counter, and  
 periodically comparing the first counter with a threshold counter value.  
 
     
     
         42 . A method as set forth in  claim 41  wherein analyzing the signal further includes, when the conditioned value is less than the filtered value, 
 setting a second flag,  
 incrementing a second counter,  
 periodically comparing the first counter with a second threshold counter value.  
 
     
     
         43 . A method as set forth in  claim 41  wherein the first and second counters are the same, and wherein the first and second threshold counter values are the same.  
     
     
         44 . A method as set forth in  claim 36  and further comprising: 
 closing the fuel valve when an output is generated signifying a non-lit fuel condition.  
 
     
     
         45 . A method as set forth in  claim 36  wherein the burner assembly includes a blower, and wherein the method further comprises: 
 deactivating the blower when an output is generated signifying a non-lit fuel condition.  
 
     
     
         46 . A method as set forth in  claim 36  wherein the burner assembly includes an alarm, and wherein the method further comprises: 
 generating an alarm when an output is generated signifying a non-lit fuel condition.