Patent ID: 6981688

Claim:
A flow control device comprising: an opening part through which an upstream side of a fluid flow passage is in communication with a downstream side of the fluid flow passage; a valve element for closing the opening part, the valve element comprising: a large flow rate controlling valve element capable of adjusting an opening degree of the opening part; a sealing member provided with a valve hole having an open area smaller than the opening part and formed to be capable of being brought into tight contact with a peripheral wall part of the opening part; and a small flow rate controlling valve element capable of adjusting an opening degree of the valve hole; and a valve drive device which rotates to drive the valve element in a closed direction for closing the opening part or in an opened direction for opening the opening part, wherein the small flow rate controlling valve element is a rod-shaped valve element formed so as to extend in a driving direction of the valve element, wherein a front end portion of the rod-shaped valve element in the driving direction of the valve element is fixed to the large flow rate controlling valve element with a diameter larger than that of the valve hole of the sealing member, wherein the sealing member is mounted to the rod-shaped valve element so as to be capable of forming a small flow rate state through a space between an outer face of the rod-shaped valve element and an inner face of the valve hole of the sealing member and a subsequent space between the sealing member and the large flow rate controlling valve element, and wherein the space between the outer face of the rod-shaped valve element and the inner face of the valve hole of the sealing member is closed according to a further movement of the rod-shaped valve element in the driving direction of the valve element.