An air flow meter for measuring the intake air of an automobile engine is\r\npresented. It is based on a miniaturized silicon thermal mass flow sensor using a thick\r\nporous Si (Po-Si) layer for local thermal isolation from the Si substrate, on which the\r\nsensor active elements are integrated. The sensor is mounted on one side of a printed\r\ncircuit board (PCB), on the other side of which the readout and control electronics of the\r\nmeter are mounted. The PCB is fixed on a housing containing a semi-cylindrical flow tube,\r\nin the middle of which the sensor is situated. An important advantage of the present air\r\nflow meter is that it detects with equal sensitivity both forward and reverse flows. Two\r\nprototypes were fabricated, a laboratory prototype for flow calibration using mass flow\r\ncontrollers and a final demonstrator with the housing mounted in an automobile engine\r\ninlet tube. The final demonstrator was tested in real life conditions in the engine inlet tube\r\nof a truck. It shows an almost linear response in a large flow range between ââ?¬â??6,500 kg/h\r\nand +6,500 kg/h, which is an order of magnitude larger than the ones usually encountered\r\nin an automobile engine.
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