Title:
AIR FLOWMETER
Document Type and Number:
Japanese Patent JPH05281008
Kind Code:
A
Abstract:
PURPOSE:To output the current supply time and the data showing the relation of the current supply time to the air flow by conducting the heating control in such a manner that a fixed current is applied to a hot-wire probe to be heated to a substantially designated temperature. CONSTITUTION:A comparator 8 outputs L when the input square wave falls by the action of constant voltage, and transistors 9, 10 respectively turn off and on to supply a fixed current to a hot-wire probe 1. The temperature of the probe 1 is increased, and the resistance value thereof is also increased to approach a designated resistance value. Accordingly, the output of a comparator 6 is gradually lowered cross the square wave, the comparator 8 outputs H, and the transistors 9, 10 turn on and off to intercept the supply of a current to the probe 1. Accordingly, the temperature of the probe 1 is reduced, and when the square wave falls, a fixed current is supplied to the probe 1 and the operation is repeated. When the supply is intercepted with a high air flow, the probe 1 is strongly cooled by an air flow, and much time is taken until the probe reaches a designated resistance value during the supply operation so that the current supply time is elongated. Accordingly, the current supply time to the probe 1 becomes an air flow signal.
Inventors:
Yu Nishimura
Application Number:
JP7950992A
Publication Date:
October 29, 1993
Filing Date:
April 01, 1992
Export Citation:
Assignee:
株式会社日立製作所
International Classes:
F02D35/00; F02D41/18; F02D45/00; G01F1/00; G01F1/68; G01F1/698; (IPC1-7): G01F1/68; F02D35/00; F02D41/18; F02D45/00
Attorney, Agent or Firm:
Ogawa Katsuo
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