PRESSURE-BASED FLOW RATE CONTROL DEVICE AND MALFUNCTION DETECTION METHOD THEREFOR

摘要

The pressure-type flow rate control device includes: a restriction part interposed in a flow channel; an upstream-side pressure sensor detecting a fluid pressure on the upstream side of the restriction part; a downstream-side pressure sensor detecting a fluid pressure on the downstream side of the restriction part; a flow control valve provided in the flow channel on the upstream side of the upstream-side pressure sensor; and computation control circuit controlling the flow control valve based on detected values of the upstream-side pressure sensor and the downstream-side pressure sensor, thereby controlling the flow. Under conditions where no fluid flow occurs in the flow channel, the computation control circuit computes the difference between the detected value of the upstream-side pressure sensor and the detected value of the downstream-side pressure sensor, and outputs a signal for pressure sensor malfunction determination based on the computed difference.