Gas appliance flame ionization current detecting circuit and detecting method thereof

Abstract

A gas appliance flame ionization current detecting circuit comprises a MCU, IO ports of MCU include a P0 port, a P1 port, a P2 port, a P3 port with MCU timing / counting functions. The gas appliance flame ionization current detecting circuit further comprises a fixed value capacitance C1, a resistor R1, a fixed value resistor R2, a first connector and a second connector. One end of the fixed value capacitance C1 is electrically connected with the P0 port, the other end of the fixed value capacitance C1 is electrically connected with the P1 port, one end of the fixed value resistor R2 and the second connector at the same. The other end of the value resistor R2 is electrically connected with the P2 port. One end of the resistor R1 is electrically connected with the P3 port, the other end of the resistor R1 is electrically connected with the first connector. An output interface of the first connector is electrically connected with a flame probe or a burner. The circuitry detection method that an output interface of the second connector is electrically connected with the burner or the flame probe includes the steps of MCU initialization, charging and discharging to the fixed value capacitance C1 continuously. The detection method has the advantages that flame equivalent impedance can be detected precisely and the affection to the precision of detection caused by environment can be removed.

Description

technical field [0001] The invention relates to a flame ion current detection circuit of a gas appliance and a detection method thereof. Background technique [0002] The flame monitoring of household gas appliances generally adopts the flame ion current method, and the existence of the flame is judged by the difference between the voltage value generated under the state of flame and without flame. different voltage values. Using the voltage comparator method, it can only output high and low states, and cannot detect the size of the ion current; using the resistance sampling sampling method, although it can relatively detect the size of the flame ion current, but in different temperature and humidity environments, the same flame The flame current value detected by the state varies greatly, so this method of detecting the current value is greatly affected by the temperature and humidity environment, and is also greatly affected by the oxidation degree of the flame probe, and...

AI Technical Summary

Problems solved by technology

Using the voltage comparator method, it can only output high and low states, and cannot detect the size of the ion current; using the resistance sampling sampling method, although it can relatively detect the size of the flame ion current, but in different temperature and humidity environments, the same flame The flame current value detected by the state varies greatly, so this method of detecting the current value is greatly affected by the temperature and humidity environment, and is also greatly affected by the oxidation degree of the flame probe, and can only be used to judge the existence of the flame; the actual application process It is often necessary to detect changes in flame combustion conditions. For example, changes in the gas-to-air ratio cause combustion conditions to deteriorate. This change in combustion conditions will cause small changes in the flame ion current. The above method has low detection accuracy and cannot accurately detect ions. The change value of the current signal, and it is impossible to judge whether the change of the flame current is caused by the change of the environment or the change of the combustion condition

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