Method and detector for detecting a flame
First Claim
1. A method for detecting a flame having a magnitude which is not less than a predetermined minimum magnitude, the method comprising:
- detecting radiation having time-varying intensity to produce a corresponding time-varying signal which has a frequency spectrum having a mid-frequency (ω
m) and a cut-off frequency (ω
g);
determining whether the time-varying signal is periodic; and
producing a flame-detection signal(i) if the time-varying signal is periodic and its mid-frequency does not exceed a first frequency value (G1) which is predetermined to be not less than flicker frequency of a stationary flame having minimum magnitude, or(ii) if the time-varying signal is not periodic and its cut-off frequency does not exceed a second frequency value (G2) which is predetermined to be greater than the first frequency value.
3 Assignments
0 Petitions
Accused Products
Abstract
A flame is detected by signal analysis for intensity variations in radiation received by a sensor. A low-frequency spectrum of the signal is analyzed for mid- and cut-off frequencies, and the signal is classified as periodic or non-periodic. Periodic signals with a mid-frequency (ωmp) above a first frequency value (G1), and non-periodic signals with a cut-off frequency (ωgc) above a second frequency value (G2) are classified as interfering signals. The first frequency value is determined by the flicker frequency of a stationary flame having a magnitude corresponding to a flame of minimum magnitude to be detected. The second frequency value is selected greater than the first frequency value (G1).
18 Citations
9 Claims
-
1. A method for detecting a flame having a magnitude which is not less than a predetermined minimum magnitude, the method comprising:
-
detecting radiation having time-varying intensity to produce a corresponding time-varying signal which has a frequency spectrum having a mid-frequency (ω
m) and a cut-off frequency (ω
g);determining whether the time-varying signal is periodic; and producing a flame-detection signal (i) if the time-varying signal is periodic and its mid-frequency does not exceed a first frequency value (G1) which is predetermined to be not less than flicker frequency of a stationary flame having minimum magnitude, or (ii) if the time-varying signal is not periodic and its cut-off frequency does not exceed a second frequency value (G2) which is predetermined to be greater than the first frequency value. - View Dependent Claims (2, 3, 4, 5, 6)
-
-
7. A flame detector comprising at least one flame-radiation sensor for detecting radiation having time-varying intensity to produce a corresponding time-varying sensor signal, and evaluation circuitry connected to the sensor for analyzing the sensor signal, the evaluation circuitry comprising:
-
a first analyzer for determining a spectral mid-frequency (ω
m) and a spectral cut-off frequency (ω
g) of the sensor signal;a second analyzer for determining whether the sensor signal is periodic; and a third analyzer for producing a flame-detection signal (i) if the sensor signal is periodic and its mid-frequency does not exceed a first frequency value (G1) which is predetermined to be not less than flicker frequency of a stationary flame having minimum magnitude, or (ii) if the sensor signal is not periodic and its cut-off frequency does not exceed a second frequency value (G2) which is predetermined to be greater than the first frequency value. - View Dependent Claims (8, 9)
-
Specification