Combustion control circuit for a fuel burner

Claim 2

A combustion control circuit for controlling the operation of a fuel burner having a burner motor and an ignition device and comprising: a triac in circuit with both the burner motor and the ignition device; a thermostat; a control circuit for placing the triac in a conductive condition to energize both the burner motor and the Ignition device in response to operation of the thermostat; a flame detector coupled to the control circuit for providing a flame indication in response to operation of the burner; means coupled to said control circuit for disabling the ignition device in response to a flame indication; a thermal delay switch for disabling the burner motor in response to being heated to a given extent; a first heater connected in said control circuit for heating said thermal delay switch during the time period beginning with operation of the thermostat and ending with production of a flame indication; and a second heater connected in circuit with the ignition device for heating said thermal delay switch during operation of the ignition device.

Claim 3

The combustion control circuit of claim 1, said thermal delay switch being connected in series with said triac.

Claim 4

A combustion control circuit for a fuel burner used to heat a space and including a burner motor and an ignition device, said combustion control circuit comprising: a switching means coupled to both the burner motor and the ignition device and operable to energize the burner motor and ignition device simultaneously; a flame detector disposed adjacent the fuel burner to provide a flame indication; a thermostatically controlled switch in the heated space movable to an operating position in response to a demand for heat; a first control means coupled to said switching means and to said thermostatically controlled switch for operating said switching means in response to movement of said thermostatically controlled switch to the operating position; a second control means coupled to said ignition device and to said flame detector for discontinuing operation of said ignition device in response to a flame indication; a thermal delay switch connected to the burner motor for preventing operation of the burner motor in response to being heated to a predetermined extent; a first heater adjacent said thermal delay switch and connected to said first and second control means for energization during operation of said first control means prior to operation of said second control means; and a second heater adjacent said thermal delay switch and connected to said ignition device for energization during operation of said ignition device.

Claim 5

A combustion control circuit for a fuel burner used to heat a space and including a burner motor and an ignition device, said combustion control circuit comprising: a switching means coupled to both the burner motor and the ignition device and operable to energize the burner motor and ignition device simultaneously; a flame detector disposed adjacent the fuel burner to provide a flame indication; a thermostatically controlled switch in the heated space movable to an operating position in response to a demand for heat; a first control means coupled to said switching means and to said thermostatically controlled switch for operating said switching means in response to movement of said thermostatically controlled switch to the operating position; a second control means coupled to said ignition device and to said flame detector for discontinuing operation of said ignition device in response to a flame indication; a thermal delay switch connected to the burner motor for preventing operation of the burner motor in response to being heated to a predetermined extent; a first heater adjacent said thermal delay switch and connected to said first and second control means for energization during operation of said first control means prior to operation of said second control means; and a second heater adjacent said thermal delay switch and connected to said ignition device for energization during operation of said ignition device.

Claim 6

The combustion control circuit of claim 3, said switching means comprising a triac.

Claim 7

The combustion control circuit of claim 4, said thermal delay switch being connected in series with said triac.

Claim 8

The combustion control circuit of claim 5, said first control means including relay means having a winding means and having a contact means connected in controlling relation to said triac, and an SCR having output electrodes and a gate electrode, said thermostatically controlled switch being coupled to said output electrodes, and said flame detector being connected to said gate electrode.

Claim 9

The combustion control circuit of claim 6, said flame detector comprising a light sensitive variable resistor, a bridge circuit including said detector in one leg, means for driving said bridge with a regulated driving signal, and a capacitor coupled to the bridge output and to the gate electrode of the SCR.

Claim 10

The combustion control circuit of claim 5, said second control means comprising a coupling transformer connected between said flame detector and said ignition device.

Claim 11

The combustion control circuit of claim 5, said second control means comprising a relay connected between said flame detector and said ignition device.

Claim 12

The combustion control circuit of claim 5, said second control means comprising a lamp and light sensitive resistor connected between said flame detector and said ignition device.

Claim 13

A combustion control circuit for a fuel burner comprising: control means for operating the burner in response to energization of the control means; a controlled conduction device including electrodes forming an output elecTrode pair and a control electrode pair; said output electrode pair being coupled to said control means for controlling the energization thereof; a variable resistance flame detection device disposed in flame sensing relation to the burner; a resistance bridge having opposed input and output terminals and having one leg including said flame detection device and having three legs including only fixed resistance; and driving signal means coupled between a source of operating potential and said bridge input terminals; said bridge output terminals being coupled to said control electrode pair of said controlled conduction device.

Claim 14

A combustion control circuit for a fuel burner comprising: control means for operating the burner in response to energization of the control means; a controlled conduction device including electrodes forming an output elecTrode pair and a control electrode pair; said output electrode pair being coupled to said control means for controlling the energization thereof; a variable resistance flame detection device disposed in flame sensing relation to the burner; a resistance bridge having opposed input and output terminals and having one leg including said flame detection device and having three legs including only fixed resistance; and driving signal means coupled between a source of operating potential and said bridge input terminals; said bridge output terminals being coupled to said control electrode pair of said controlled conduction device.

Claim 15

The combustion control circuit of claim 11, said controlled conductive device comprising an SCR.

Claim 16

The combustion control circuit of claim 11, said detection device comprising a photoelectric cell.

Claim 17

The combustion control circuit of claim 11, said driving signal means including a zener diode.

Claim 18

The combustion control circuit of claim 11, said flame detection device having dark and light resistance conditions, said fixed resistances being chosen so that the bridge is unbalanced in response to the absence of flame and oppositely unbalanced in response to the presence of flame.

Claim 19

A combustion control circuit for controlling a fuel burner installation including a burner motor and an ignition circuit of the type including an ignition circuit gated device periodically rendered conductive by a gating signal to create a burner ignition condition, said combustion control circuit including: motor start means and motor hold means coupled to the burner motor for sequentially initiating and then maintaining operation of the burner motor; a normally conductive controlled conduction device including electrodes forming an output electrode pair and a control electrode pair; said output electrode pair being coupled to said motor start means for controlling the energization thereof; a variable resistance flame detection device disposed in flame sensing relation to the burner; a resistance bridge having opposed input and output terminals and having one leg including said flame detection device; and driving signal means coupled between a source of operating potential and said bridge input terminals; said bridge output terminals being coupled to said control electrode pair of said controlled conduction device for rendering said controlled conduction device nonconductive in response to detection of flame to disable said motor start means; and an ignition disabling circuit coupled between said output electrode pair and the ignition circuit gated device for disabling the gated device in response to detection of flame.

Claim 20

A combustion control circuit for controlling a fuel burner installation including a burner motor and an ignition circuit of the type including an ignition circuit gated device periodically rendered conductive by a gating signal to create a burner ignition condition, said combustion control circuit including: motor start means and motor hold means coupled to the burner motor for sequentially initiating and then maintaining operation of the burner motor; a normally conductive controlled conduction device including electrodes forming an output electrode pair and a control electrode pair; said output electrode pair being coupled to said motor start means for controlling the energization thereof; a variable resistance flame detection device disposed in flame sensing relation to the burner; a resistance bridge having opposed input and output terminals and having one leg including said flame detection device; and driving signal means coupled between a source of operating potential and said bridge input terminals; said bridge output terminals being coupled to said control electrode pair of said controlled conduction device for rendering said controlled conduction device nonconductive in response to detection of flame to disable said motor start means; and an ignition disabling circuit coupled between said output electrode pair and the ignition circuit gated device for disabling the gated device in response to detection of flame.

Claim 21

A combustion control circuit for a fuel burner installation of the type including a burner motor and an ignition circuit having an active element, said combustion control circuit comprising in combination: a triac having a gate electrode and having output electrodes connected in current supplying relation between a power source and both said motor and said ignition circuit; a thermal switch connected in current supplying relation with the motor; a flame sensitive variable resistance device adjacent the burner; a bridge circuit including said device in one leg; means for driving said bridge with a regulated voltage; a capacitor connected to said bridge for storing a potential corresponding to the balance condition of the bridge; a controlled conduction device having a control electrode coupled to said capacitor for conduction in response to the absence of flame and for nonconduction in response to the absence of flame; a relay having pull-in winding means and hold winding means and having a normally open set of contacts coupled to the gate electrode of said triac; means including a thermostat for energizing said hold winding means and said controlled conduction device in response to a demand for heat; said pull-in windIng means being connected for energization by said controlling conduction device; an ignition disabling means coupled between said controlled conduction device and the ignition circuit active element for disabling the active element in response to nonconduction of said controlled conduction device; a first heater for said thermal switch connected in circuit with said pull-in winding means; and a second heater for said thermal switch connected in circuit with said ignition circuit.

Claim 22

A combustion control circuit for a fuel burner installation of the type including a burner motor and an ignition circuit having an active element, said combustion control circuit comprising in combination: a triac having a gate electrode and having output electrodes connected in current supplying relation between a power source and both said motor and said ignition circuit; a thermal switch connected in current supplying relation with the motor; a flame sensitive variable resistance device adjacent the burner; a bridge circuit including said device in one leg; means for driving said bridge with a regulated voltage; a capacitor connected to said bridge for storing a potential corresponding to the balance condition of the bridge; a controlled conduction device having a control electrode coupled to said capacitor for conduction in response to the absence of flame and for nonconduction in response to the absence of flame; a relay having pull-in winding means and hold winding means and having a normally open set of contacts coupled to the gate electrode of said triac; means including a thermostat for energizing said hold winding means and said controlled conduction device in response to a demand for heat; said pull-in windIng means being connected for energization by said controlling conduction device; an ignition disabling means coupled between said controlled conduction device and the ignition circuit active element for disabling the active element in response to nonconduction of said controlled conduction device; a first heater for said thermal switch connected in circuit with said pull-in winding means; and a second heater for said thermal switch connected in circuit with said ignition circuit.

Claim 23

The circuit of claim 17, said thermal switch being in series with said triac.

Claim 24

The circuit of claim 17, said controlled conduction device comprising an SCR.

Claim 25

The circuit of claim 17, said thermostat being in series with said triac.

Claim 26

The circuit of claim 17, said thermostat being connected in current supplying relation to said pull-in winding means and said hold winding means.

Claim 27

The circuit of claim 17, said disabling means comprising a transformer.

Claim 28

The circuit of claim 17, said disabling means comprising a relay.

Claim 29

The circuit of claim 17, said disabling means comprising a lamp and a light sensitive resistance.

Claim 30

A combustion control circuit for a fuel burner and for an ignition circuit including an ignition circuit SCR and including a gating circuit for periodically applying a gating signal to the cathode and gate electrodes of the ignition circuit SCR for producing an ignition condition, said combustion control circuit comprising: control means for operating the burner in response to energization of the control means; a solid state controlled conduction device having a control electrode and having output electrodes coupled to said control means for controlling the energization thereof; a flame detection circuit coupled to the control electrode of said solid state controlled conductive device for rendering said device nonconductive in response to detection of burner flame; and an ignition disabling circuit coupled between said solid state controlled conduction device and said ignition circuit; said disabling circuit including a transformer having one winding connected across the output electrodes of the solid state controlled conduction device and having another winding connected across the cathode and gate electrodes of the ignition circuit SCR to reverse bias the ignition circuit SCR in response to nonconduction of said solid state controlled conductive device. A combustion control circuit for a fuel burner and for an ignition circuit including an ignition circuit SCR and including a gating circuit for periodically applying a gating signal to the cathode and gate electrodes of the ignition circuit SCR for producing an ignition condition, said combustion control circuit comprising; control means for operating the burner in response to energization of the control means; a solid state controlled conduction device having output electrodes coupled to said control means for controlling the energization thereof; a flame detection circuit coupled to the control electrode of said solid state controlled conduction device for rendering said device nonconductive in response to detection of burner flame; and an ignition disabling circuit between said solid state controlled conduction device and said ignition circuit; said disabling circuit including a lamp connected across the output electrodes of the solid state controlled conduction device and a light sensitive resistance connected across the cathode and gate electrodes of the ignition circuit SCR to prevent gating of the ignition circuit SCR in response to nonconduction of said solid state controlled conduction device.

Claim 31

A combustion control circuit for a fuel burner and for an ignition circuit including an ignition circuit SCR and including a gating circuit for periodically applying a gating signal to the cathode and gate electrodes of the ignition circuit SCR for producing an ignition condition, said combustion control circuit comprising: control means for operating the burner in response to energization of the control means; a solid state controlled conduction device having a control electrode and having output electrodes coupled to said control means for controlling the energization thereof; a flame detection circuit coupled to the control electrode of said solid state controlled conductive device for rendering said device nonconductive in response to detection of burner flame; and an ignition disabling circuit coupled between said solid state controlled conduction device and said ignition circuit; said disabling circuit including a transformer having one winding connected across the output electrodes of the solid state controlled conduction device and having another winding connected across the cathode and gate electrodes of the ignition circuit SCR to reverse bias the ignition circuit SCR in response to nonconduction of said solid state controlled conductive device. A combustion control circuit for a fuel burner and for an ignition circuit including an ignition circuit SCR and including a gating circuit for periodically applying a gating signal to the cathode and gate electrodes of the ignition circuit SCR for producing an ignition condition, said combustion control circuit comprising; control means for operating the burner in response to energization of the control means; a solid state controlled conduction device having output electrodes coupled to said control means for controlling the energization thereof; a flame detection circuit coupled to the control electrode of said solid state controlled conduction device for rendering said device nonconductive in response to detection of burner flame; and an ignition disabling circuit between said solid state controlled conduction device and said ignition circuit; said disabling circuit including a lamp connected across the output electrodes of the solid state controlled conduction device and a light sensitive resistance connected across the cathode and gate electrodes of the ignition circuit SCR to prevent gating of the ignition circuit SCR in response to nonconduction of said solid state controlled conduction device.