PROBLEM TO BE SOLVED: To reduce sliding resistance between a plunger and an inner wall of a pipeline of a cylinder.SOLUTION: A valve guide member 30 of a cylinder unit 24 includes a first large-diameter pipeline 40 communicating with a suction channel 17, a second small-diameter pipeline 41, and a cone-shaped pipeline 42 for connecting both the pipelines 40 and 41 together. The inner wall of the cone-shaped pipeline 42 is provided with a negative pressure source communication opening 45 communicating with a negative pressure source channel 21. The plunger 25 for opening/closing the negative pressure source communication opening 45 is housed in the valve guide member 30. A shaft end portion 52a of the plunger 25 and a leading end of the valve guide member 30 are connected together by means of a cap 26 made of an elastic material. Rotation between the plunger 25 and the cap 26 is regulated. Rotation between the valve guide member 30 and the cap 26 is regulated. Thus, rotation between the plunger 25 and the valve guide member 30 can be indirectly regulated via the cap 26, so that they need no rotation stopper that causes the sliding resistance.COPYRIGHT: (C)2012,JPO&INPIT【課題】プランジャとシリンダの管路内壁との摺動抵抗を抑える。【解決手段】シリンダユニット24の弁ガイド部材30に、吸引通路17に通じる太径の第1管路40と、細径の第2管路41と、両管路40,41を接続する錐形管路42とを設ける。錐形管路42の内壁に、負圧源通路21に通じる負圧源連通口45を設ける。弁ガイド部材30内に負圧源連通口45を開閉するプランジャ25を収容する。プランジャ25の軸先端部52aと、弁ガイド部材30の先端とを弾性材料からなるキャップ26により連結する。プランジャ25とキャップ26との間の回転規制を行う。弁ガイド部材30とキャップ26との間の回転規制を行う。これにより、キャップ26を介して間接的にプランジャ25と弁ガイド部材30との間の回転規制を行うことができるので、両者にそれぞれ摺動抵抗の発生要因となる回転止めを設ける必要がなくなる。【選択図】図2
