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A variable delivery type fuel supply apparatus capable of suppressing variation of fuel pressure within a delivery pipe and hence variation of fuel quantity injected through fuel injection valves and simplifying a control method therefor. The apparatus includes an oil relief passage (6) provided bet

A variable delivery type fuel supply apparatus capable of suppressing variation of fuel pressure within a delivery pipe and hence variation of fuel quantity injected through fuel injection valves and simplifying a control method therefor. The apparatus includes an oil relief passage (6) provided between the suction port of a fuel pump (4) and a pressurizing chamber (4e) across a suction valve (4a) of the fuel pump (4), an electromagnetic valve (7) disposed in the oil relief passage (6) and opened for a predetermined time during a discharge stroke of the fuel pump (4) for thereby controlling a discharge quantity of the fuel pump (4), and a control unit (108) for controlling the timing at which the electromagnetic valve (7) is opened. The control unit (108) is so designed as to control open/close operations of the electromagnetic valve (7) such that a time point for starting electrical energization of the electromagnetic valve (7) is fixedly set at a predetermined time point relative to the suction/discharge stroke of the fuel pump (4) while allowing the time point for terminating the electrical energization to be variable, to thereby control the discharge quantity of the fuel pump (4).

대표청구항 ▼

1. 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 di

1. 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. 2. A variable delivery type fuel supply apparatus according to claim 1, wherein said control unit is so designed that an electromagnetic valve driving current is increased to a high level immediately after electrical energization of said valve is started while said electromagnetic valve driving current is held at a low level after lapse of a predetermined time since the start of said electrical energization.