FUEL SUPPLY PUMP

PROBLEM TO BE SOLVED: To provide a relief valve structure which exhibits stable and high fuel opening characteristics and a fuel supply pump which mounts the relief valve structure thereon, as an inexpensive structure.SOLUTION: A fuel supply pump includes a pressurizing chamber which pressurizes fuel and a relief valve mechanism which returns fuel in an ejection channel of the down stream side of an ejection valve to the pressurizing chamber or a low-pressure channel. Therein, the relief valve mechanism includes a valve seat which closes a relief channel by seating the relief valve, a relief valve holder which holds the relief valve and a relief spring which energizes the relief valve toward the valve seat via the relief valve holder and, on the relief valve holder, a hole part for reducing flux of fuel which flows between an opposite part and the valve seat when the relief valve is opened so as to penetrate in the relief valve shaft direction on the opposite part opposed to the valve seat is formed.SELECTED DRAWING: Figure 1 【課題】安定して高い燃料開放特性を発揮するリリーフ弁構造と、それを搭載した燃料供給ポンプを、安価な構造により提供すること。【解決手段】燃料を加圧する加圧室と、前記吐出弁の下流側の吐出通路の燃料を前記加圧室、又は低圧通路に戻すリリーフ弁機構と、を備えた燃料供給ポンプにおいて、前記リリーフ弁機構は、リリーフ弁が着座することでリリーフ流路を閉弁する弁座と、前記リリーフ弁を保持するリリーフ弁ホルダと、前記リリーフ弁ホルダを介して前記リリーフ弁を前記弁座に向かって付勢するリリーフバネと、を備え、前記リリーフ弁ホルダには前記弁座に対向する対向部においてリリーフ弁軸方向に貫通して、前記リリーフ弁が開弁した場合に前記対向部と前記弁座との間を流れる燃料の流速を低減させる孔部が形成する。【選択図】図１