Patent ID: 9188521
Filing Date: 2015-11-17
Classification: G01N

Abstract:
1. A method for controlling the concentration of a gaseous component of a gaseous mixture, said mixture being recirculated by a ventilator in a cooking chamber of an oven, for cooking foods in said chamber, said oven being supplied with power at a predetermined mains frequency and voltage, said ventilator being driven by an asynchronous electric motor of known speed of synchronism, said gaseous mixture being subjected in said chamber to a known pressure, the method comprising: detecting a temperature of the gaseous mixture in the cooking chamber, varying the voltage of the power supply of the motor in order to maintain the rotation speed of the motor at a predetermined value, measuring of the difference between the mains voltage at which the motor is supplied with power and the voltage at which the motor rotates at the predetermined speed, using said voltage difference, said temperature and said known pressure to determine the concentration of said component in the mixture, comparing the concentration of the component which is found with a desired concentration value and, adjusting the concentration of said component in the cooking chamber on the basis of the comparison carried out, wherein the predetermined speed of the motor is obtained by phase-cutting of the power supply voltage of the motor, at constant frequency.