The long point where the quiet note instrument (iv) washing injector (20) the assembly body includes, penetrates and possesses, the areola in order to keep the fluid (33) picture forming inside doing, the surface (32) with, the proximal edge which is opened (28) with, the distal (2036) wall (31) the distal (2036) edge which is included (30) with the tube which it possesses (22) the areola (33) with the fluid the passage which is communicated (38) (36) extends from this distal (2036) wall to distal (2036). The long substance part (25) with, the tube (22) the inside surface (32) with the stopper which smooth movement unrestrictedly is arranged (54) with the piston which it possesses (24) is provided with liquid dense engagement. The areola (33) from forwarding the fluid completing, when stopper (54) the distal (2036) wall (31) contacting, it can provide the counterflow prevention structure which controls deflecting the stopper. This counterflow prevention structure includes, is, the distal (2036) surface of conical form (59) the stopper which it possesses (54) with, the tube (22) the inside surface (32) with the distal (2036) wall (31) conical form (35), the distal (2036) wall (31) the tube in (22) the inside surface (32) all the included angles A stopper (54) the distal (2036) surface (59) the 6 are larger than all the included angles B at least.静注器具(IV)洗浄注射器(20)組立体は、流体を保持するための小室(33)を画成する内側表面(32)と、開放した近位端(28)と、遠位壁(31)を含む遠位端(30)とを有する筒(22)を含み、貫通して小室(33)と流体連通する通路(38)を有する細長い先端(36)がこの遠位壁から遠位へ延びる。細長い本体部分(25)と、筒(22)の内側表面(32)と液密係合で滑動自在に配置されたストッパ(54)とを有するピストン(24)が設けられる。小室(33)から流体を送出することが完了して、ストッパ(54)が遠位壁(31)に接触するときにストッパの撓みを制御する逆流防止構造が設けられる。この逆流防止構造は、円錐形状の遠位表面(59)を有するストッパ(54)と、筒(22)の内側表面(32)とを含み、遠位壁(31)は円錐形状(35)であり、遠位壁(31)における筒(22)の内側表面(32)の全先端角Aは、ストッパ(54)の遠位表面(59)の全先端角Bよりも少なくとも6°大きい。
