Ultraviolet flame detector

Claim 2

A monitoring circuit for use in series with an alternating current power supply and a flame responsive electrical element having a normal operating impedance range, a first modified impedance range when said element is exposed to and operatively associated with a flame emitted from a burner, and a second modified impedance range when said element is defectively shorted, said modified ranges being substantially less than said normal range and said second modified range being substantially less than said first modified range, said monitoring circuit comprising: a. a continuously active first circuit for allowing current flow through said element in a first direction; b. a normally non-active second circuit for allowing current flow through said element in a second direction opposite to said first direction; c. means responsive to operation of said element in said second modified range for rendering said second circuit active whereby alternating current flow is established through said element; and, d. an output means for controlling said burner; and, e. control means responsive to alternating current flow through said element for activating said output means.

Claim 3

A monitoring circuit as defined in claim 1 wherein said first circuit includes a first half wave rectifier means poled in said first direction and a first resistor in series with said first rectifier means.

Claim 4

A monitoring circuit as defined in claim 2 wherein said second circuit is connected in parallel with said first resistor and includes a second half wave rectifier means poled in said second direction and voltage responsive means for rendering said second circuit conductive when the voltage across said first resistor means exceeds a preselected level.

Claim 5

A monitoring circuit as defined in claim 3 wherein said voltage responsive means is a means for blocking current flow until said preselected level is exceeded.

Claim 6

A monitoring circuit as defined in claim 1 wherein said control means is a capacitor means connected in series with said element, said capacitor means having a first charged condition when charged with only first current flow in said first direction, said first current flow occuring when said element is operating in said first modified range and a second charged condition when charged with current flow in both said first and second directions, and means responsive to said second charged condition for actuating said output means.

Claim 7

A monitoring circuit as defined in claim 5 wherein said capacitor means has a third charged condition when charged with only a second current flow in said first direction, said second current flow occurring when said element is operating in said normal range, and means responsive to said third charged condition for actuating said output means.

Claim 8

A flame detector for detecting whether a flame is emitted from a burner, said detector comprising: a. an electrical element positioned in operative relationship to any flame emitted from said burner and having a normal operating impedance range, a first modified impedance range when exposed to radiation, and a second modified impedance range when defectively shorted, with said modified ranges being lower than said normal range and said second modified range being substantially lower than said first modified range; b. a first circuit including a capacitor, a first half wave rectifier means for allowing unidirectional current flow in a first direction, a first resistor and said element; c. voltage supply means for applying an alternating circuit across said first series circuit whereby said capacitor is changed with a first polarity corresponding to said uni-directional current flow; d. a second series circuit connected in parallel with said first rectifier means and said first resistor, said second series circuit comprising a second half wave rectifier means for allowing unidirectional current flow in a second direction through said second direction opposite to said first direction for changing said capacitor with a second polarity and voltage responsive means for allowing current flow through said second series circuit when voltage exceeding a preselected voltage applied across said second series circuit, said preselected value being exceeded only when said element is operating in said second modified range; e. an output control means; and, f. means responsive to changing of said capacitor with said second polarity for operating said output control means.

Claim 9

A flame detector for detecting whether a flame is emitted from a burner, said detector comprising: a. an electrical element positioned in operative relationship to any flame emitted from said burner and having a normal operating impedance range, a first modified impedance range when exposed to radiation, and a second modified impedance range when defectively shorted, with said modified ranges being lower than said normal range and said second modified range being substantially lower than said first modified range; b. a first circuit including a capacitor, a first half wave rectifier means for allowing unidirectional current flow in a first direction, a first resistor and said element; c. voltage supply means for applying an alternating circuit across said first series circuit whereby said capacitor is changed with a first polarity corresponding to said uni-directional current flow; d. a second series circuit connected in parallel with said first rectifier means and said first resistor, said second series circuit comprising a second half wave rectifier means for allowing unidirectional current flow in a second direction through said second direction opposite to said first direction for changing said capacitor with a second polarity and voltage responsive means for allowing current flow through said second series circuit when voltage exceeding a preselected voltage applied across said second series circuit, said preselected value being exceeded only when said element is operating in said second modified range; e. an output control means; and, f. means responsive to changing of said capacitor with said second polarity for operating said output control means.

Claim 10

A flame detector as defined in claim 7 wherein said second series circuit includes a second resistor with said second resistor having substantially lesser resistance than said first resistor.

Claim 11

A flame detector as defined in claim 7 wherein said voltage responsive means includes at least one voltage responsive discharge element.

Claim 12

A flame detector for detecting whether a flame is emitted from a burner member, said detector comprising: a. an electrically conductive element having the property of less resistance when exposed to ultraviolet radiation than when not so exposed, positioned so as to be in operative relationship to a flame emitted from said burner member; b. a first rectifier and first resistor in series witH said conductive element to form a flame responsive unit with unidirectional current properties; c. an electronic control means having first, second and third electrodes, normally in non-conducting condition; d. first circuit means including a second resistor for connecting said first and second electrodes and said flame responsive unit in a series circuit across an alternating current circuit of relatively high voltage; e. second circuit means for connecting said first and third electrodes across an alternating current circuit of lower voltage whereby when flame is emitted from said burner member rectified direct current flows through said first circuit means for causing conduction of said control means; f. a branch circuit connected in parallel with said first resistor and said first rectifier, said branch circuit comprising in electrical series a second rectifier and voltage responsive means for allowing current flow through said branch circuit when a voltage exceeding a preselected voltage is applied across said parallel branch circuit, said second rectifier being poled oppositely to said first rectifier with respect to current flow through said first circuit means, whereby in the event of a short circuit of said conductive element sufficient current flows through said first resistor to raise the voltage across said voltage responsive means to a value above said preselected value and current flows through said parallel branch circuit in a direction opposite to current flow through said first rectifier.

Claim 13

A flame detector for detecting whether a flame is emitted from a burner member, said detector comprising: a. an electrically conductive element having the property of less resistance when exposed to ultraviolet radiation than when not so exposed, positioned so as to be in operative relationship to a flame emitted from said burner member; b. a first rectifier and first resistor in series witH said conductive element to form a flame responsive unit with unidirectional current properties; c. an electronic control means having first, second and third electrodes, normally in non-conducting condition; d. first circuit means including a second resistor for connecting said first and second electrodes and said flame responsive unit in a series circuit across an alternating current circuit of relatively high voltage; e. second circuit means for connecting said first and third electrodes across an alternating current circuit of lower voltage whereby when flame is emitted from said burner member rectified direct current flows through said first circuit means for causing conduction of said control means; f. a branch circuit connected in parallel with said first resistor and said first rectifier, said branch circuit comprising in electrical series a second rectifier and voltage responsive means for allowing current flow through said branch circuit when a voltage exceeding a preselected voltage is applied across said parallel branch circuit, said second rectifier being poled oppositely to said first rectifier with respect to current flow through said first circuit means, whereby in the event of a short circuit of said conductive element sufficient current flows through said first resistor to raise the voltage across said voltage responsive means to a value above said preselected value and current flows through said parallel branch circuit in a direction opposite to current flow through said first rectifier.

Claim 14

A detector as described in claim 10, wherein a filter capacitor is provided bridging the circuit of said first and second electrodes to serve with said second resistor as an integrator, bypassing said first and second electrodes to prevent said control means from becoming conductive during, fault of said ultraviolet radiation responsive element.

Claim 15

A flame detector for detecting whether a flame is emitted from a burner, said detector comprising: a. an electrical element positioned in operative relationship to a flame emitted from said burner and having a normal operating impedance range, a first modified impedance range when exposed to radiation, and a second modified impedance range when defectively shorted, with said modified ranges being lower than said normal range and said second modified range being substantially lower than said first modified range; b. first and second mutually parallel circuits each connected in series with said electrical element; c. said first parallel circuit comprising a first resistor and a first half wave rectifier means for allowing flow of current in a first direction through said first parallel circuit and said element while said element is operating in any of said impedance ranges; d. said second parallel circuit comprising a second half wave rectifier means for allowing flow of current in a second direction through said second parallel circuit and said element, said second direction being opposite to said first direction, and voltage responsive means for allowing current flow through said second parallel circuit when a voltage exceeding a preselected voltage is applied across said parallel circuits; e. voltage supply means for applying an alternating circuit across said elements and said parallel circuits whereby a unidirectional current above a given value and in said first direction flows through said first parallel circuit when said element is operating in either of said first and second modified ranges and unidirectional current flows in a second direction and through said second parallel branch only when said element is operating in said second modified range; f. an output means having a first condition selected for non-existence of a flame emitted from said burner and a second condition selected for existence of such a flame; g. control means having a first state created by unidirectional current flow in said first direction and below said given value, a second state creatEd by unidirectional current in said first direction and above said given value and a third state created by current flow in both of said unidirectional directions; h. means for shifting said output means into said first condition when said control means is in said first or third state; and, i. means for shifting said output means into said second condition when said control means is in said second state.

Claim 16

A flame detector for detecting whether a flame is emitted from a burner, said detector comprising: a. an electrical element positioned in operative relationship to a flame emitted from said burner and having a normal operating impedance range, a first modified impedance range when exposed to radiation, and a second modified impedance range when defectively shorted, with said modified ranges being lower than said normal range and said second modified range being substantially lower than said first modified range; b. first and second mutually parallel circuits each connected in series with said electrical element; c. said first parallel circuit comprising a first resistor and a first half wave rectifier means for allowing flow of current in a first direction through said first parallel circuit and said element while said element is operating in any of said impedance ranges; d. said second parallel circuit comprising a second half wave rectifier means for allowing flow of current in a second direction through said second parallel circuit and said element, said second direction being opposite to said first direction, and voltage responsive means for allowing current flow through said second parallel circuit when a voltage exceeding a preselected voltage is applied across said parallel circuits; e. voltage supply means for applying an alternating circuit across said elements and said parallel circuits whereby a unidirectional current above a given value and in said first direction flows through said first parallel circuit when said element is operating in either of said first and second modified ranges and unidirectional current flows in a second direction and through said second parallel branch only when said element is operating in said second modified range; f. an output means having a first condition selected for non-existence of a flame emitted from said burner and a second condition selected for existence of such a flame; g. control means having a first state created by unidirectional current flow in said first direction and below said given value, a second state creatEd by unidirectional current in said first direction and above said given value and a third state created by current flow in both of said unidirectional directions; h. means for shifting said output means into said first condition when said control means is in said first or third state; and, i. means for shifting said output means into said second condition when said control means is in said second state.

Claim 17

A flame detector for detecting whether a flame is emitted from a burner member and comprising: a. an electrically conductive element having the property of less resistance when exposed to ultraviolet radiation than when not so exposed, positioned so as to be in operative relationship to a flame emitted from said burner member; but insulated therefrom; b. a rectifier in series with said element to form a flame responsive unit with unidirectional current properties; c. an electronic control means having first, second and third electrodes, normally in non-conducting condition; d. circuit means including an integrator comprising: e. a resistor for connecting said first and second electrodes and said flame responsive unit in a series circuit across an alternating-current circuit of relatively high voltage and second circuit means for connecting said first and third electrodes across an alternating-current circuit of lower voltage whereby when flame is emitted from said burner member rectified direct current flows through said series circuit for causing conduction of said control means; and, f. a branch circuit in parallel with the unit comprising said resistor and said rectifier, said branch circuit comprising a rectifier and a discharge means in series, said second mentioned rectifier being poled oppositely to the first mentioned rectifier with respect to the first mentioned series circuit, whereby in the event of short circuit of said ultraviolet radiation responsive element sufficient current flows through said resistor to raise the voltage across said discharge means to the discharge level causing alternating current to flow through said first mentioned series circuit.

Claim 18

A flame detector for detecting whether a flame is emitted from a burner member and comprising: a. an electrically conductive element having the property of less resistance when exposed to ultraviolet radiation than when not so exposed, positioned so as to be in operative relationship to a flame emitted from said burner member; but insulated therefrom; b. a rectifier in series with said element to form a flame responsive unit with unidirectional current properties; c. an electronic control means having first, second and third electrodes, normally in non-conducting condition; d. circuit means including an integrator comprising: e. a resistor for connecting said first and second electrodes and said flame responsive unit in a series circuit across an alternating-current circuit of relatively high voltage and second circuit means for connecting said first and third electrodes across an alternating-current circuit of lower voltage whereby when flame is emitted from said burner member rectified direct current flows through said series circuit for causing conduction of said control means; and, f. a branch circuit in parallel with the unit comprising said resistor and said rectifier, said branch circuit comprising a rectifier and a discharge means in series, said second mentioned rectifier being poled oppositely to the first mentioned rectifier with respect to the first mentioned series circuit, whereby in the event of short circuit of said ultraviolet radiation responsive element sufficient current flows through said resistor to raise the voltage across said discharge means to the discharge level causing alternating current to flow through said first mentioned series circuit.

Claim 19

A detector as described in claim 13, wherein a filter capacitor is provided bridging the circuit of said first and second electrodes to serve with said resistor as an integrator, bypassing said first and second electrodes to prevent the flow of direct current in said first-mentioned series circuit and prevent said control means from becoming conductive during fault of said ultraviolet radiation responsive element.