Patent ID: 7621726

Claim:
A metering pump comprising: a delivery plunger which can be reciprocally moved to and fro in an axial direction between a first axial position and a second axial position to deliver liquid medium; a guide sleeve which partially accommodates said delivery plunger and guides said delivery plunger for the reciprocating movement, said guide sleeve with an inner surface thereof defining a pump ejection chamber and with an outer surface thereof defining a channel arrangement leading to said pump ejection chamber; a carrier element, said guide sleeve being carried in said carrier element and said guide sleeve having a first axial length area with an outer circumferential surface in contact with said carrier element essentially over an entire outer circumference of said guide sleeve and said guide sleeve having a second axial length area with an outer surface located at a spaced location from said carrier element, wherein said channel arrangement is provided between said carrier element and said guide sleeve in said second length area, said guide sleeve having at least one support area in said second length area for supporting said guide sleeve in relation to said carrier element, said guide sleeve defining said pump ejection chamber essentially in said first axial length area, said guide sleeve defining said channel arrangement essentially in said second axial length area, said guide sleeve having at least one passage opening, said at least one passage opening defining a means for communicating said channel arrangement with said pump ejection chamber, said at least one passage opening being in communication with said pump ejection chamber when said delivery plunger is in said first axial position, said delivery plunger closing said at least one passage opening when said plunger is in said second axial position such that said channel arrangement is not in communication with said pump ejection chamber.