The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 08, 2007
Filed:
Dec. 16, 2004
Chihiro Kobayashi, Naka, JP;
Shinya Igarashi, Naka, JP;
Chihiro Kobayashi, Naka, JP;
Shinya Igarashi, Naka, JP;
Hitachi, Ltd., Tokyo, JP;
Hitachi Car Engineering Co., Ltd., Ibaraki, JP;
Abstract
A thermal type gas flow measuring instrument measures gas flow with high precision by accurately correcting changes in radiation heat characteristics of a heating resistor due to contamination. The instrument comprises a second heating resistorwhose resistance value, which changes if contaminated, is calculated by measuring the terminal voltage thereof by calculating meansand the calculated value is compared with a temperature detected by a temperature detecting elementBased on the result of comparison, the level of contamination of the second heating resistoris determined. The second heating resistorand the first heating resistorare disposed in similar environments such that their levels of contamination can be considered equal. Based on the level of contamination calculated from the result of comparison, a correction value is calculated and the output of the first heating resistoris corrected in accordance with the correction value.