Denso Corporation

Hiroyuki Nishimura

Katsunori Furuta

Masashi Suzuki

Yukihiro Shinohara

Takashi Kikutani

Akihiro Kuroda

Toshikazu Watanabe

Takuya Sakai

Tohru Takahashi

A pressure reducing valve control apparatus is provided for a fuel supply system having a common rail and a pressure reducing valve to control rail pressure in the common rail by controlling a current supply state of the pressure reducing valve. The pressure reducing valve operates to open a valve body for discharging fuel from the common rail against a biasing force applied in a valve-closing direction by fuel-generated valve-opening force biasing the valve body in a valve-opening direction by the rail pressure and an electromagnetic force generated by current supply to an electromagnetic coil. The ECU starts to open the valve body during a period of holding a hold value by holding current supplied to the electromagnetic coil at a predetermined hold value after starting current supply to the electromagnetic coil. The ECU sets the hold value to increase as the rail pressure decreases.

Pressure reducing valve control apparatus

A control device executes an overlap injection operation, in which one of the plurality of injectors is energized first to inject fuel, and a next one of the plurality of injectors is energized to inject fuel after starting of the energization of the one of the plurality of injectors while the one of the plurality of injectors is still kept energized. The control device corrects an energization period of the next one of the injectors by lengthening the energization period of the next one of the injectors in comparison to a normal energization period of the next one of the injectors, which is set for a non-overlap injection operation of the next one of the plurality of injectors.

Fuel injection system executing overlap injection operation

In a flow amount control device, column shaped valve element is slidably disposed in a cylindrical inner circumferential wall of a valve body. The valve element is provided along an outer circumference thereof with two ring shaped grooves. Fuel stored in the ring shaped grooves serves to form film of oil for lubrication in a sliding clearance between the valve element and the valve body so that frictional resistance therebetween is smaller and the valve element slides smoothly on the valve body. Accordingly, the device can control flow amount of fuel accurately.

Flow amount control device

In a flow amount control device which control flow amount of fuel to be supplied to a high pressure fuel pump, an opening, which communicates with a port for passing fuel to the high pressure fuel pump, is composed of a first rectangular opening, a second rectangular opening whose circumferential length is larger than that of the first opening, and a third trapezoidal opening bridging between the first and second openings. The port communicates with the first opening, when engine speed is low, and, as the engine speed increases, with the third and second openings. Accordingly, the flow amount of fuel to be discharged from the high pressure fuel pump varies non-linearly and a change of the flow amount thereof is small in engine low speed region.

In order to prevent a damage on a component forming a pressure feed fuel passage and to reduce a fuel injection pump in size and weight, the pressure feed fuel passage having fuel discharge passage, fuel chamber and accommodation hole formed in respective cylinder heads is formed straightly in respective cylinder heads, and has communication port for communicating with fuel pressure chamber and fuel outlet which has an opening at an outer peripheral wall of the cylinder heads. Fuel pressurized in fuel pressure chamber at the cylinder head side is introduced into fuel chamber of cylinder head via fuel passage and fuel lines. Fuel pressurized in both fuel pressure chambers is merged at fuel chamber of cylinder head, and is supplied to a common-rail via fuel passage.

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Kariya, Japan

Hiroyuki Nishimura