Patent ID: 6546918
Filing Date: 2003-04-15
Classification: F02D,F02M,F04B

Abstract:
A variable delivery type fuel supply apparatus, comprising:a fuel pump including a suction valve which is opened during a suction stroke for sucking a fuel in a pressurizing chamber in the course of reciprocation of a plunger within a cylinder and a discharge valve which is opened during a discharge stroke for discharging the fuel from said pressurizing chamber into a high-pressure fuel delivery passage of an internal combustion engine equipped with fuel injection valves in the course of reciprocation of said plunger within said cylinder; an oil relief passage provided between a suction port of said fuel pump and said pressurizing chamber across said suction valve of said fuel pump so as to interconnect said suction port and said pressurizing chamber; a normally closed electromagnetic valve, which is designed to be opened by an electrical energization, disposed in said oil relief passage and opened for a predetermined time during the discharge stroke of said fuel pump for thereby controlling a fuel discharge quantity of said fuel pump, wherein said electromagnetic valve includes a valve element which is subjected to a high pressure in a direction perpendicular to an axial direction of a valve closing spring; and a control unit for controlling timing at which said electromagnetic valve is opened, wherein said control unit is so designed as to control open/close operations of said electromagnetic valve such that a time point for opening said electromagnetic valve by starting said electrical energization of said electromagnetic valve is fixedly set at a predetermined time point relative to the suction/discharge stroke of said fuel pump while allowing a time point for terminating said electrical energization and closing said electromagnetic valve to be variable, to thereby control the fuel discharge quantity of said fuel pump.