HOLLOW PLUNGER FOR PLUNGER PUMP

摘要

PROBLEM TO BE SOLVED: To prevent the leakage of a fluid between a hollow plunger for a plunger pump and a pump body. SOLUTION: A cylindrical part 31 having a hollow portion 30 open to a pump chamber 2 is formed in a hollow plunger for a plunger pump. The cylindrical part 31 is expanded outside in the radial direction by pressure granted to a fluid during the discharge of the fluid to make a clearance to a cavity portion 3 in slide contact smaller than that when mounted or during drawing the fluid. Accordingly, the clearance due to geometrical error and thermal expansion is compensated with the expansion of the plunger 4 to prevent the leakage of the fluid between the plunger 4 and the cavity portion 3.