Patent ID: 7703320
Filing Date: 2010-04-27
Classification: G01F

Abstract:
1. A flow measuring device for measuring a flow of air in an air passage, the flow measuring device comprising: an electrically insulating film that is provided in the air passage, the electrically insulating film having a planar shape that extends generally in parallel with a direction of the flow of air; a heating element that is provided on a surface of the electrically insulating film for generating heat when the heating element is energized; an upstream detection resistor assembly that is provided on the surface of the electrically insulating film upstream of the heating element in the flow direction of air, the upstream detection resistor assembly having a first plurality of resistors, an electrical resistance of each of the first plurality of resistors being changeable depending on a temperature; and a downstream detection resistor assembly that is provided on the surface of the electrically insulating film downstream of the heating element in the flow direction of air, the downstream detection resistor assembly having a second plurality of resistors, an electrical resistance of each of the second plurality of resistors being changeable depending on a temperature, wherein: the flow of air that flows in the air passage is measured based on a difference between (a) a detection of the upstream detection resistor assembly and (b) a detection of the downstream detection resistor assembly; and when a longitudinal axis is defined to extend in parallel with the surface of the electrically insulating film and perpendicularly to the flow direction of air, and when a flow direction coordinate axis is defined to extend on the surface of the electrically insulating film in parallel with the flow direction, and when a longitudinal direction coordinate axis is defined to extend on the surface of the electrically insulating film in parallel with the longitudinal axis, the following conditions are satisfied: a part of one of the first plurality of resistors and a part of an other of the first plurality of resistors are arranged in one nesting arrangement; a part of one of the second plurality of resistors and a part of an other of the second plurality of resistors are arranged in another nesting arrangement; and parts of the first plurality of resistors and the second plurality of resistors extend continuously along the longitudinal axis adjacent a part of the heating element that corresponds to said mid-point of the heating element along the longitudinal axis, whereby heat generated by the heating element around said mid-point of the heating element is caused to inevitably flow over the continuously longitudinally extending parts of the resistors.