| 摘要 |
PURPOSE:To enable delicate control in the wider range while restraining costs by forming an opening edge of a flow control hole into a sectional form, and integrally forming a first taper part on the base end side and a second taper part on the tip side having the cone angle larger than that of the first taper part. CONSTITUTION:A flow control mechanism is composed of a valve body 6 connected to a stepping motor through a connecting part 13, and to be vertically moved, and a seat member 5 on which the valve body 6 sits. The valve body 6 is formed into a taper shape wherein its outside dimension is gradually decreased toward the tip side from the base end side. The valve body 6 is integrally formed by a first taper part 16 on the base end side, having the different cone angle, and a second taper part 17 on the tip side, and the boundary line is set in the position for dividing the valve body 6 at a ratio of 2 to 1. And, the cone angle alpha of the first taper part 16 is set to 37.5 deg., and the cone angle betaof the second taper part is set to 50 deg., that is, they are so set as to satisfy the relationship: alpha<beta. |
