| 摘要 |
PURPOSE:To obtain a flow rate control device having a high safety property by detecting an uneven rotation of an impeller, etc., cutting off a fluid path before becoming a dangerous state, and informing an abnormality. CONSTITUTION:When a setting signal for controlling a flow rate is applied, a driving circuit 21 brings a coil 12 of a proportional control valve 1a to electric conduction, opens a valve body 8 through a plunger 10 and makes a fluid flow to an outlet 6. This flow rate is detected 18 as a pulse signal by a permanent magnet 16 and a Hall element 17 by a rotation of an impeller 15 of a flow rate sensor 3. It is compared 20 with said setting signal through an integrator 19, and controls an opening of said valve 1. A safety circuit 23 is provided on this valve controlling circuit 4, a detecting pulse signal of said flow rate is inputted to a pulse period ratio detecting circuit 24, and a ratio of a pulse period is calculated. This ratio is compared 25 with a prescribed ratio set by a setting device 26, and when it becomes other ratio than said prescribed ratio, a discriminating circuit 28 and a timer circuit 29 are turned on. When it is continued for a prescribed time, a cutting-off circuit 30 and an informing circuit 31 are operated, and cutting-off, etc. of the valve 1 are executed. |
