Method and apparatus for monitoring variation in the current value of a rate of fluid flow through a flow meter

A fluid meter comprising a measurement unit for measuring a volume of fluid, which unit is connected to a rotary shaft for which each revolution represents a volume of fluid passing through said measurement unit, and apparatus for monitoring variation in the current value of the fluid flow rate on the basis of rotation of said shaft wherein said apparatus comprises:

• at least one sensor placed facing the path of at least one mark associated with the rotary shaft and designed to deliver an output bit depending on the position of said sensor relative to said mark;
• means for generating consecutive electrical signals at a sampling frequency that is variable between two frequencies in application of a predetermined sampling relationship to power said optical sensor, each frequency value being defined as a function of at least one predetermined fluid flow rate value;
• means for forming an output signal on the basis of the binary output states delivered by the sensor, said output signal representing the succession in time of bits corresponding to detection and non-detection of a rotary movement of the shaft;
• and
• electronic bit processing means for processing said bits depending on said sampling frequency in order to determine the current value of the fluid flow rate over a continuum of flow rates and relative to the predetermined fluid flow rate value on which the value of the sampling frequency depends.