Combustion control apparatus for burner

Claim 2

A combustion control apparatus for a burner comprising: a photosensor for detecting a light power signal from a flame generated from the burner; a low-pass filter for cutting off a component of the light power signal detected by said photosensor which is above a specific frequency to obtain a low-frequency light power signal; a frequency analyzer for frequency-analyzing the low-frequency light power signal obtained through said low-pass filter to obtain a power spectrum; arithmetic means for computing an integral value of said power spectrum in the entire frequency band and an integral value of said power spectrum in a frequency band above a preset reference frequency, computing a power spectrum integral ratio from these integral values, comparing the power spectrum integral ratio with a reference integral ratio previously set in correspondence with each particular excess air ratio, and outputting data representative of the result of the comparison; and air flow control means for controlling an air supply control valve of said burner on the basis of said comparison data.

Claim 3

A combustion control apparatus for a burner comprising: a detector for detecting an ionic current in a flame from the burner or light power of the flame, which changes in accordance with a change of combustion condition of the flame, and outputting an electric signal corresponding to the detected ionic current or light power; an amplifier for amplifying said electric signal; a low-pass filter connected to the output side of said amplifier to remove a high-frequency component in said electric current, said low pass filter including a first and second output branch line; a first circuit connected to the first output branch line of said low-pass filer to rectify the signal current having passed through said low-pass filter and thereby obtain a signal current in the form of a direct current; a high-pass filter connected to the second output branch line of said low-pass filter to remove a low-frequency component in the signal current having passed through said low-pass filter; a second circuit connected in the second output branch line to rectify the signal current having passed through said high-pass filter and thereby obtain a signal current in the form of a direct current; an arithmetic unit connected to the output sides of said first and second branch lines to arithmetically determined a relation of the signal current in a specific frequency band to the signal current in the entire frequency band; and a combustion controller connected to the output side of said arithmetic unit to affect combustion control on the basis of the output from said arithmetic unit.

Claim 4

A combustion control apparatus for a burner comprising: a detector for detecting an ionic current in a flame from the burner or light power of the flame, which changes in accordance with a change of combustion condition of the flame, and outputting an electric signal corresponding to the detected ionic current or light power; an amplifier for amplifying said electric signal; a low-pass filter connected to the output side of said amplifier to remove a high-frequency component in said electric current, said low pass filter including a first and second output branch line; a first circuit connected to the first output branch line of said low-pass filer to rectify the signal current having passed through said low-pass filter and thereby obtain a signal current in the form of a direct current; a high-pass filter connected to the second output branch line of said low-pass filter to remove a low-frequency component in the signal current having passed through said low-pass filter; a second circuit connected in the second output branch line to rectify the signal current having passed through said high-pass filter and thereby obtain a signal current in the form of a direct current; an arithmetic unit connected to the output sides of said first and second branch lines to arithmetically determined a relation of the signal current in a specific frequency band to the signal current in the entire frequency band; and a combustion controller connected to the output side of said arithmetic unit to affect combustion control on the basis of the output from said arithmetic unit.