LOW LEAKAGE PLUNGER AND BARREL ASSEMBLY FOR HIGH PRESSURE FLUID SYSTEM

摘要

An improved plunger and barrel assembly (30) is provided which includes a plunger (36) reciprocally mounted in a cavity (34) formed in the barrel (32) and a leakage flow reduction device (38) positioned in the cavity for reducing fluid leakage flow around the plunger (36) thus increasing system efficiency. The leakage flow reduction device (38) includes a sealing sleeve (40) removably mounted in the cavity (34) between the plunger (36) and barrel (32) which includes a bore (42) for slidably receiving the plunger (36) to form an annular clearance gap (62) between the plunger (36) and the bore (42). The sealing sleeve (40) is designed to resiliently flex in response to fluid pressure forces to reduce the annular clearance gap (62) so as to mimimize fluid leakage through the annular clearance gap (62). The sealing sleeve (40) is formed as a separated piece from the barrel to permit simple, low cost replacement. The sealing sleeve (40) is preferably applied to a fuel pump having a plunger (36) for pressurizing fuel in a high pressure chamber (56).