CAM ARRANGEMENT AND FUEL PUMP ARRANGEMENT INCORPORATING A CAM ARRANGEMENT

摘要

A cam arrangement for use with a high pressure fuel pump arrangement for delivering fuel to an associated engine, the cam arrangement including at least two cams (28) that are mounted, in use, upon an engine camshaft and each of which is arranged to drive a respective pumping plunger (16) of the fuel pump arrangement, wherein each plunger is driven to perform a pumping stroke, against return biasing means (32), during which fuel within a pump chamber (22) associated with each plunger is pressurised, and whereby said return biasing means (32) effects a plunger return stroke, and wherein each cam (28) is oriented relative to the or each other cam and has a surface (50) shaped such that the associated plunger return stroke is interrupted to define at least one step of plunger movement that is substantially synchronous with the pumping stroke of another of the plungers (16) of the pump, thereby to reduce negative torque loading of the camshaft.