PROBLEM TO BE SOLVED: To prevent gas from being mixed in a water supply route when supplying water in a three-way stopcock for switching water supply and drainage.SOLUTION: The three-way stopcock 20 includes a valve element 31 provided with three-way passage 46 opened in three directions and a cock body 32 for rotatably supporting the valve element 31 inside. When the valve element 31 is at a water supply position, two openings of an aqueduct 47 in the three-way passage 46 are communicated with first and second holes 41, 42 respectively. A branch route 48 in the three-way passage 46 flows pressurized gas for drainage and does not communicate with the first to third holes 41 to 43 at the water supply position. At the water supply position, a plunger 53 closes the third hole 43 airtightly and prevents the gas from entering the aqueduct 47 via the third hole 43. When the valve element 31 rotates at 180° and comes at a drainage position, and the opening of the branch route 48 communicates with the third hole 43, the plunger 53 releases the third hole 43.COPYRIGHT: (C)2012,JPO&INPIT【課題】送水と排水とを切り換えるための三方活栓において、送水時に気体が送水経路に混入することを防止する。【解決手段】三方活栓20は、三方に開口された三方通路46が設けられた弁体31と、弁体31を内部に回転可能に支持するコック本体32と備える。弁体31が送水位置にあるとき、三方通路46の送水路47の2つの開口それぞれが、第1及び第2の孔41、42に連通する。また、三方通路46の分岐路48は、排水用の加圧気体を流入させるためのものであって、送水位置では第1ないし第3の孔41~43に連通しない。送水位置では、ピストン53が第3の孔43を気密的に塞ぎ、第3の孔43を介して、気体が送水路47に入るのを防ぐ。弁体31が180°回転し排水位置になって、分岐路48の開口が第3の孔43に連通すると、ピストン53は第3の孔43を開放する。【選択図】図3
