| 摘要 |
PROBLEM TO BE SOLVED: To overcome the problem in a conventional thermal type flowmeter that is lacking in consideration related to a failure of a control circuit, although it can determine the failure of a detecting element. SOLUTION: A heating element temperature control system is composed of a heating element 3, a heating element temperature detection means 5, a subtraction unit 9, an integrator 10, a subtraction unit 7 and a heating element driving means 6, and disturbance generated by a disturbance generator 8 is input to the heating element temperature control system in such a manner that the disturbance is subtracted from an output of the integrator 10 by the subtraction unit 7. A failure of the heating element temperature control system is determined in a failure decision means 11 by comparing an output of the disturbance generator 8 with the output of the integrator 10. When the failure decision means 11 determines the failure, a flow rate signal is fixed to the ground potential by a switching circuit 13. COPYRIGHT: (C)2011,JPO&INPIT |
