Patent ID: 7596457

Claim:
An electrically operated valve diagnosing method for diagnosing a driving force of an electrically operated valve provided with a valve element driving section for driving open and closed a valve element by using a revolving drive force of a worm to which a revolving drive force is imparted by an electromotive power, and with a spring cartridge expanded and contracted in response to a reaction force acting on an axial direction of said worm in the valve element driving section, said method comprising: providing a first correlation database which records a correlation between a driving force output signal from said valve element driving section and a driving force obtained from a compression state of said spring cartridge for both of an open operation and closed operation of the electrically operated valve; acquiring a correlation between a driving force input signal to said valve element driving section and said driving force output signal, and monitoring a state of change in a transmission efficiency of the driving force in said valve element driving section on the basis of the acquired correlation; acquiring a value of the driving force output signal by measurement; reading out, from said first correlation database, a value of said driving force corresponding to the value of the driving force output signal acquired by measurement; and diagnosing, on the basis of the read out value of the driving force, an appropriateness of the driving force of the electrically operated valve.