Flame responsive system

Claim 2

A flame responsive system comprising a flame sensor that produces an electrical signal derived from the monitored flame environment, a first circuit responsive to the electrical signal from said flame sensor for producing an output signal indicative of the flame condition in the monitored flame environment, and a second circuit also responsive to the electrical signal from said flame sensor, said second circuit having a slower response time than that of said first circuit, said second circuit being arranged to produce in response to a change in said electrical signal that indicates a decrease in magnitude of flame in the monitored flame environment an output that inhibits generation by said first circuit of signals indicating the presence of flame in the monitored flame environment.

Claim 3

The system as claimed in claim 1 wherein said first circuit includes an integrator network, and threshold responsive circuitry responsive to said integrator network for producing a flame condition output signal, and said second circuit output is coupled to inhibit generation of said flame condition signal by said threshold responsive circuitry.

Claim 4

The system as claimed in claim 2 wherein said second circuit includes a second integrator network that has a much slower response time than said first integrator network and second threshold responsive circuitry responsive to said second integrator network for producing said second circuit output.

Claim 5

The system as claimed in claim 1 and further including offset circuitry responsive to said second circuit output for changing the reference threshold signal applied to said second circuit.

Claim 6

The system as claimed in claim 1 wherein said first circuit includes a fast response network, a first comparator circuit and a one shot circuit responsive to said comparator for producing periodic output pulses in response to signals from said fast response network, and said second circuit output is coupled to clamp said fast response network and inhibit generation of output pulses by said one shot circuit.

Claim 7

The system as claimed in claim 1 wherein said first circuit includes a fast response network and said second circuit includes a slow response network that has a much slower response time than said fast response network, a comparator circuit, means to apply a reference threshold signal to said comparator circuit, said comparator circuit being arranged to produce said second circuit output in response to a decrease in output of said slow response network below said reference threshold, and offset circuitry responsive to said second circuit output for increasing the reference threshold signal applied to said comparator circuit.

Claim 8

The system as claimed in claim 5 wherein said fast response network includes a first integrator network, and said fast circuit further includes first threshold responsive circuitry responsive to said first integrator network for producing a flame condition output signal, and said second circuit output is coupled to inhibit generation of said flame condition signal by said first threshold responsive circuitry.

Claim 9

The system as claimed in claim 7 wherein said second circuit includes a second integrator network that has a much slower response time than said first integrator network and second threshold responsive circuitry responsive to said second integrator network for producing said second circuit output.

Claim 10

The system as claimed in claim 8 wherein said flame sensor is a solid state device that has a photosensitive junction region.

Claim 11

The system as claimed in claim 1 and further including flame signal enhancing circuitry coupled to said flame sensor, said flame signal enhancing circuitry having a first response as a function of the monitored flame component of said electrical signal and a second response different from said first response as a function of the background component of said electrical signal and being arranged to provide an enhanced flame signal representative of the monitored flame as an output signal for application to said first and second circuits.

Claim 12

The system as claimed in claim 10 and further including selective attenuation circuitry coupled between said flame signal enhancing circuitry and said first and second circuits, said selective attenuation circuitry attenuating components of said output signal corresponding to the frequency range of said background component of said electrical signal.

Claim 13

The system as claimed in claim 11 wherein said selective attenuation circuitry has a low frequenty cutoff that excludes all signals in the range of said background component.

Claim 14

The system as claimed in claim 10 and further including gain adjustment means for varying the magnitude of said enhanced flame signal and detector circuitry coupled between said flame signal enhancing circuitry and said first and second circuits.

Claim 15

The system as claimed in claim 1 and further including flame failure simulation means for periodically simulating a flame failure condition and wherein the response time of said first circuit is a fraction of the duration of the flame failure condition simultated by said simulation means.

Claim 16

The system as claimed in claim 14 wherein said first circuit includes an integrator network, and threshold responsive circuitry responsive to said integrator network for producing a flame condition output signal, and said second circuit output is coupled to inhibit generation of said flame condition signal by said threshold responsive circuitry.

Claim 17

The system as claimed in claim 15 wherein said second circuit includes a second integrator network that has a much slower response time than said first integrator network and second threshold responsive circuitry responsive to said second integrator network for producing said second circuit output.

Claim 18

A flame responsive system comprising a solid state flame sensor device that has a photosensitive region and produces an electrical signal derived from the monitored flame environment, flame signal enhancing circuitry coupled to said flame sensor and including an amplifier and a feedback network arranged so that the influence of said monitored flame component is enhanced and the influence of said background component is attenuated, said flame signal enhancing circuitry being arranged to provide an enhanced flame signal representative of the monitored flame, a first circuit responsive to said enhanced flame signal for producing an output signal indicative of the flame condition in the monitored flame environment, said first circuit including a first integrator network and first threshold circuitry responsive to said first integrator network for producing said flame condition output signal, a second circuit also responsive to said enhanced flame signal, said second circuit including a second integrator network that has a much slower response time than said first integrator network and second threshold responsive circuitry responsive to said second integrator network for producing a second circuit output, said second circuit output being coupled to inhibit generation of said flame condition output signal by said first circuit when said enhanced flame signal falls below the reference threshold signal applied to said second threshold responsive circuitry.

Claim 19

A flame responsive system comprising a solid state flame sensor device that has a photosensitive region and produces an electrical signal derived from the monitored flame environment, flame signal enhancing circuitry coupled to said flame sensor and including an amplifier and a feedback network arranged so that the influence of said monitored flame component is enhanced and the influence of said background component is attenuated, said flame signal enhancing circuitry being arranged to provide an enhanced flame signal representative of the monitored flame, a first circuit responsive to said enhanced flame signal for producing an output signal indicative of the flame condition in the monitored flame environment, said first circuit including a first integrator network and first threshold circuitry responsive to said first integrator network for producing said flame condition output signal, a second circuit also responsive to said enhanced flame signal, said second circuit including a second integrator network that has a much slower response time than said first integrator network and second threshold responsive circuitry responsive to said second integrator network for producing a second circuit output, said second circuit output being coupled to inhibit generation of said flame condition output signal by said first circuit when said enhanced flame signal falls below the reference threshold signal applied to said second threshold responsive circuitry.

Claim 20

The system as claimed in claim 17 wherein said feedback network includes an impedance element that has a damped response to said electrical signal.

Claim 21

The system as claimed in claim 18 wherein said enhancing circuitry includes a radiation source coupled to be energized by the output of said amplifier and said impedance element is a slow speed photoresistor that is optically coupled to said radiation source.

Claim 22

The system as claimed in claim 19 wherein said flame signal enhancing circuitry has a transfer function of the form ##EQU2## where n is in the range of 0.6-0.8.

Claim 23

The system as claimed in claim 17 and further including offset circuitry responsive to said second circuit output for increasing the reference threshold signal applied to said second threshold responsive circuitry.

Claim 24

The system as claimed in claim 21 and further including flame failure simulation means for periodically simulating a flame failure condition and wherein the response time of said first circuit is a fraction of the duration of the flame failure condition simulated by said simulation means and the response time of said second circuit is greater than the duration of the flame failure condition simulated by said simulation means.

Claim 25

A flame responsive system comprising a flame sensor that produces an electrical signal derived from the monitored flame environment, flame failure simulation means for periodically simulating a flame failure condition, a first circuit responsive to the electrical signal from said flame sensor for producing an output signal indicative of the flame condition in the monitored flame environment, the response time of said first circuit being a fraction of the duration of the flame failure condition simulated by said simulation means, a second circuit also responsive to the electrical signal from said flame sensor, said second circuit having a response time slower than that of said first circuit and greater than the duration of the flame failure condition simulated by said simulation means, said second circuit arranged to produce an output that inhibits generation by said first circuit of signals indicating the presence of flame in the monitored flame environment, means for applyiing a reference threshold signal to said second circuit, and offset circuitry responsive to said second circuit output for changing the reference threshold signal applied to said second circuit.

Claim 26

A flame responsive system comprising a flame sensor that produces an electrical signal derived from the monitored flame environment, flame failure simulation means for periodically simulating a flame failure condition, a first circuit responsive to the electrical signal from said flame sensor for producing an output signal indicative of the flame condition in the monitored flame environment, the response time of said first circuit being a fraction of the duration of the flame failure condition simulated by said simulation means, a second circuit also responsive to the electrical signal from said flame sensor, said second circuit having a response time slower than that of said first circuit and greater than the duration of the flame failure condition simulated by said simulation means, said second circuit arranged to produce an output that inhibits generation by said first circuit of signals indicating the presence of flame in the monitored flame environment, means for applyiing a reference threshold signal to said second circuit, and offset circuitry responsive to said second circuit output for changing the reference threshold signal applied to said second circuit.

Claim 27

The system as claimed in claim 23 and further including flame signal enhancing circuitry coupled to said flame sensor, said flame signal enhancing circuitry having a first response as a function of the monitored flame component of said electrical signal and a second response different from said first response as a function of the background component of said electrical signal and being arranged to provide an enhanced flame signal representative of the monitored flame as an output signal for application to said first and second circuits.

Claim 28

In a flame responsive system, a signal processor responsive to a flame sensor that produces an electrical signal derived from the monitored flame environment comprising flame signal generating circuitry, a first circuit responsive to said electrical signal for actuating said flame signal generating circuitry, flame signal inhibiting circuitry and a second circuit responsive to said electrical signal for actuating said flame signal inhibiting circuitry, said first circuit having a faster response time than said second circuit and said first and second circuits being associated so that total loss of flame sensor response results in rapid termination of flame signal output from said flame signal generating circuitry and reduction of flame sensor response to a level below a set point causes said flame signal inhibiting circuitry to inhibit said flame signal output.

Claim 29

In a flame responsive system, a signal processor responsive to a flame sensor that produces an electrical signal derived from the monitored flame environment comprising flame signal generating circuitry, a first circuit responsive to said electrical signal for actuating said flame signal generating circuitry, flame signal inhibiting circuitry and a second circuit responsive to said electrical signal for actuating said flame signal inhibiting circuitry, said first circuit having a faster response time than said second circuit and said first and second circuits being associated so that total loss of flame sensor response results in rapid termination of flame signal output from said flame signal generating circuitry and reduction of flame sensor response to a level below a set point causes said flame signal inhibiting circuitry to inhibit said flame signal output.

Claim 30

The system as claimed in claim 25 wherein said signal generating circuitry includes a first comparator circuit and a one shot circuit responsive to said comparator for producing periodic output pulses in response to signals from said first circuit, and said signal inhibiting circuitry is coupled to clamp said first circuit and inhibit generation of output pulses by said one shot circuit.

Claim 31

The system as claimed in claim 26 wherein said signal inhibiting circuitry includes a second comparator circuit responsive to the output of said second circuit.

Claim 32

The system as claimed in claim 27 and further including offset circuitry responsive to said signal inhibiting circuitry output for changing the reference threshold signal applied to said second comparator.

Claim 33

The system as claimed in claim 28 and further including flame signal enhancing circuitry coupled to said flame sensor, said flame signal enhancing circuitry having a first response as a function of the monitored flame component of said sensor signal and a second response different from said first response as a function of the background component of said sensor signal and being arranged to provide an enhanced flame signal representative of the monitored flame as an output signal for application to said signal processor.