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US 4,264,961 AGranted
Air flow rate measuring apparatus
AssigneeHitachi, Ltd.
InventorsYutaka Nishimura, Yoshishige Oyama
Life of this patent
Estimating the term…
Abstract
An apparatus for measuring the flow rate of suction air in an internal combustion engine in which the heat radiation characteristic of a heat generator disposed in the suction air passage, which characteristic varies with the lapse of time due to dust and like foreign matters depositing on the heat generator, is calibrated on the basis of the air flow rate value measured by an air flow rate measuring device of differential pressure type so as to insure accurate measurement of the suction air flow rate.
Claims12
An air flow rate measuring apparatus for an internal combustion engine comprising:
- pressure sensor means for generating an output representative of a differential pressure .DELTA.P which varies depending on the variation in the flow rate of suction air flowing through the main venturi of the engine, said pressure sensor means being coupled with a bypass path of the main venturi;
- thermal type air flow rate measuring means, including electrical heat-generating means located in the stream of suction air, for sensing the quantity of heat radiated into the stream of air from said heat-generating means and generating an output V corresponding to the radiated quantity of heat;
- first means for arithmetically calculating the flow rate G of suction air flowing through the main venturi in accordance with the output V of said measuring means and a coefficient K varying with the lapse of time on the basis of a first predetermined algebraic function;
- second means for arithmetically calculating the flow rate G of suction air flowing through the main venturi in accordance with the output .DELTA.P of said pressure sensor means in accordance with a second predetermined algebraic function;
- third means for arithmetically obtaining a calibrated coefficient K' in accordance with the flow rate G obtained by said second means and the output V of said measuring means in accordance with said first predetermined algebraic function;
- and
- fourth means for arithmetically calculating a suitable suction air flow rate G' in accordance with the calibrated coefficient K' and the output V of said measuring means in accordance with said first predetermined algebraic function.
4 more elements
An air flow rate measuring apparatus for an internal combustion engine comprising:
- pressure sensor means for generating an output representative of a differential pressure .DELTA.P, across two spaced predetermined points, which pressure .DELTA.P varies depending upon the variation in the flow rate of suction air flowing through the main venturi of the engine, said pressure sensor means being coupled with a bypass path of the main venturi;
- supporting means for supporting electrical heat-generating means within a predetermined air passage;
- thermal type air flow rate measuring means, including electrical heat-generating means located in the stream of suction air, for sensing the quantity of heat radiated into the stream of air from said heat-generating means and generating an output V corresponding to the radiated quantity of heat;
- first means for arithmetically calculating the flow rate G of suction air flowing through the main venturi in accordance with the output V of said measuring means and a coefficient K varying with the lapse of time on the basis of a first predetermined algebraic function;
- second means for arithmetically calculating the flow rate G of suction air flowing through the main venturi in accordance with the output .DELTA.P of said pressure sensor means in accordance with a second predetermined algebraic function;
- third means for arithmetically obtaining a calibrated coefficient K' in accordance with the flow rate G obtained by said second means and the output V of said measuring means in accordance with said first predetermined algebraic function;
- and
- fourth means for arithmetically calculating a suitable suction air flow rate G' in accordance with the calibrated coefficient K' and the output V of said measuring means in accordance with said first predetermined algebraic function.
5 more elements
Dependencies are inferred from the claim text.