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Poppet valves : ウィキペディア英語版 | Poppet valve
A poppet valve (also called mushroom valve) is a valve typically used to control the timing and quantity of gas or vapour flow into an engine. It consists of a hole, usually round or oval, and a tapered plug, usually a disk shape on the end of a shaft also called a valve stem. The portion of the hole where the plug meets with it is referred to as the 'seat' or 'valve seat'. The shaft guides the plug portion by sliding through a valve guide. In exhaust applications a pressure differential helps to seal the valve and in intake valves a pressure differential helps open it. Poppet valves date from at least the 1770s, when James Watt used them on his steam engines. ==Etymology== The word poppet shares etymology with "puppet": it is from the Middle English ''popet'' ("youth" or "doll"), from Middle French ''poupette'', which is a diminutive of ''poupe''. The use of the word ''poppet'' to describe a valve comes from the same word applied to marionettes, which – like the poppet valve – move bodily in response to remote motion transmitted linearly. In the past, "puppet valve" was a synonym for ''poppet valve''; however, this usage of "puppet" is now obsolete.
抄文引用元・出典: フリー百科事典『 ウィキペディア(Wikipedia)』 ■ウィキペディアで「Poppet valve」の詳細全文を読む
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