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:
Aug. 30, 2005
Filed:
Aug. 14, 2001
Junichi Horie, Chiyoda-ku, JP;
Izumi Watanabe, Ibaraki, JP;
Shinya Igarashi, Ibaraki, JP;
Keiichi Nakada, Chiyoda-ku, JP;
Kei Ueyama, Chiyoda-ku, JP;
Junichi Horie, Chiyoda-ku, JP;
Izumi Watanabe, Ibaraki, JP;
Shinya Igarashi, Ibaraki, JP;
Keiichi Nakada, Chiyoda-ku, JP;
Kei Ueyama, Chiyoda-ku, JP;
Hitachi, Ltd., Tokyo, JP;
Hitachi Car Engineering Co., Ltd., Hitachinaka, JP;
Abstract
A thermal type flow measuring device comprises a heating resistor(HF), a temperature measuring resistor(Ru) upstream of the heating resistor(HF) with respect to a fluid(Q), and a temperature measuring resistor(Rd) downstream of the heating resistor(HF). A heat sensitive resistance element(CF), the upstream temperature measuring resistor(Ru) and the downstream temperature measuring resistor(Rd) form a first bridge circuit, and this first bridge circuit and the heating resistor(HF) form a second bridge circuit. Feedback control means(OP, Tr) heat the heating resistor(HF) in accordance with an output for keeping a balance of the second bridge circuit. The distance between the heat sensitive resistance element(CF) and the heating resistor(HF) is larger than the distance between the upstream temperature measuring resistor(Ru) or the downstream temperature sensitive resistor(Rd) and the heating resistor(HF) so that the heat sensitive resistance element(CF) is positioned to receive less thermal influences from the heating resistor(HF) than the upstream temperature measuring resistor(Ru) and the downstream temperature sensitive resistor(Rd). The upstream temperature measuring resistor or the downstream temperature measuring resistor is heated by the heating resistor, and the flow rate of the fluid is measured based on an output for keeping a balance of the first bridge circuit.