摘要 |
A pump for an engine includes a suction chamber, a discharge chamber, and a piston at least partly received within a relief chamber. The piston has first and second passageways provided therein. The second passageway is located closer to a face of the piston than the first passageway. The piston is movable within the relief chamber, so that the volume of the fluid transfer from the suction chamber to the discharge chamber is varied according to a pressure in the relief chamber. The first and second passageways form fluid paths between the suction chamber and the discharge chamber at a first and second pressure in the relief chamber, respectively, the first pressure being less than the second pressure. |