System for active regulation of the air/gas ratio of a burner including a differential pressure measuring system

A system for active regulation of air/gas ratio of a burner, comprising an air/gas mixer upstream of the burner, an air pipe housing a calibrated air diaphragm and connected to a first inlet of said air/gas mixer, a gas supply pipe housing a calibrated gas diaphragm and connected to a second inlet of said air/gas mixer means for varying a flowrate of air and means for varying a flowrate of gas sent to said air/gas mixer, and at least one differential pressure measuring system connected to deliver a measurement signal representative of at least one of the following three parameters:

• the air flowrate in the air pipe, the difference between air and gas pressures in the air pipe and the gas pipe, and the gas flowrate in the gas pipe, so that the quantity of gas sent to the air/gas mixer is such that the air/gas ratio has a predefined value, wherein each of said differential pressure measuring systems comprises:
• a differential pressure sensor having first and second inlet orifices respectively connected to first and second pressure ports, one of said pressure ports comprises a calibrated throttling orifice, and an output configured to deliver a signal representative of a pressure difference between the first and second inlet orifices of said sensor,
• a 2-channel valve, a first channel of which is connected to whichever of the first and second pressure ports contains said calibrated throttling orifice, between that calibrated orifice and the corresponding inlet orifice of the sensor, and whose second channel is connected to the other of the first and second pressure ports, said calibrated orifice having a flow section significantly smaller than that of said 2-channel valve and said 2-channel valve isolating one of the two inlet orifices from the other when it is in a first state and connecting them to each other when it is in a second state,
• memory means connected to the output of each sensor to store at least two values of the output signal of each sensor, a control unit connected to said 2-channel valve and to the memory means to switch said 2-channel valve and control storage of a first value of the output signal of the sensor in said memory means when the 2-channel valve is in its first state and storage of a second value of the output signal of the sensor in said memory means when the 2-channel valve is in its second state, and
• means for calculating a difference between said first and second values of the output signal of the sensor, said memory means and said difference calculating means forming a measurement circuit which delivers at its output a measurement signal representative of the value of a difference between respective pressures at the first and second inlet orifices of each sensor.