Flow rate sensor implementing a plurality of inner tubes located within a sensor tube

A flow rate sensor for detecting a flow rate of a fluid, said flow rate sensor comprising:

• a sensor tube operable to allow a fluid to flow therein;
• a sensor tube guide adapted to cover said sensor tube and contact said sensor tube;
• a plurality of narrow inner tubes provided within said sensor tube;
• a pair of heating resistors operable to heat said sensor tube, said pair of heating resistors provided on said sensor tube guide;
• a temperature sensor operable to control temperatures of said pair of heating resistors, said temperature sensor being positioned equidistant from opposite ends of said sensor tube;
• a case adapted to hold said pair of heating resistors and said temperature sensor;
• and
• a voltage applying device operable to set an increase in temperature of each of said pair of heating resistors;
• wherein said sensor tube has opposite ends thereof thermally connected to said case;
• and
• wherein said flow rate sensor is adapted to detect a flow rate of the fluid flowing in said sensor tube based on variations of voltages applied to said pair of heating resistors, the variations occurring according to the flow rate of the fluid.