US 6,644,269 B2Granted

Fuel injection system having pre-injection and main injection

AssigneeDenso Corporation

InventorsMasaaki Kato, Toshiyuki Yoda, Kenji Date

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Abstract

The angle of fuel spray at the time of pre-injection is set to a wider angle of spray and the angle of fuel spray at the time of main injection is set to a narrower angle of spray. The pre-injection timing is set so that when fuel spray after the pre-injection is diffused in a cylinder and stratified, the stratified fuel spray is ignited by a rise in the pressure in the cylinder in association with movement of a piston from the bottom dead center to the top dead center. The main injection timing is set so that when the spray stratified by the pre-injection is burned, the fuel spray injected by the main injection passes through the combustion zone while being ignited in the combustion zone, reaches a combustion chamber of the piston, and is burned in the combustion chamber.

Claims15

Dependent claims

A fuel injection system comprising:

a nozzle body having a nozzle hole via which fuel is injected into a cylinder of an internal combustion engine;
a needle which is slidably provided in the axial direction in the nozzle body and opens and closes the nozzle hole;
a control chamber for introducing a fuel pressure to a back pressure side of the needle to bias the needle in a valve closing direction;
a control valve for controlling a pressure in the control chamber;
means for lifting the needle in stages according to a balance among the fuel pressure which biases the needle in a valve opening direction, a biasing force of a plurality of biasing means which urge the needle in a valve closing direction, and a force of the pressure in the control chamber which biases the needle in the valve closing direction;
and
a fuel passage which is provided between the needle and the nozzle body and by which a rate of injection and spray conditions of a fuel to be injected are changed according to a lift of the needle,
wherein the fuel passage is formed by an oblique groove formed on a conical surface of the needle facing a conical surface of the nozzle body and a passage which is formed, when the needle lifts, to increase a distance between the conical surfaces of the needle and the nozzle body so that a swirl flow rate over an entire range of lifting of the needle is continuously changed as the needle lifts;
the needle includes a valve seat which seats on a conical surface of the nozzle body to close the nozzle hole;
and
the conical surfaces of the nozzle body respectively facing the oblique groove and the valve seat are formed in a same tapered surface of the nozzle body so that the conical surfaces have the same inclination relative to a longitudinal axis of the nozzle body.

8 more elements

A fuel injection system comprising:

a nozzle body having a valve seat member upstream of a nozzle hole;
a needle which is supported by the nozzle body slidably in stages and reciprocally and has a contact part which can seat on the valve seat member, for interrupting and flowing a fuel by making the contact part unseated and seated on the valve seat member;
a first swirl flow generating chamber formed in the nozzle body, for generating a swirl flow of a fuel;
and
a first swirl flow generating part which is provided around the needle and has an outer wall in which a first fuel inlet passage communicated with a fuel upstream side of the first swirl flow generating chamber is formed,
wherein an outer surface of the first swirl flow generating part in which the first fuel inlet passage is formed faces an inner surface of the nozzle body in which the valve seat member is formed, and
wherein the first swirl flow generating chamber is formed to have a tapered surface on a side of the nozzle body, the tapered surface being formed downstream of the inner surface of the nozzle body facing die first swirl flow generating part;
and
the tapered surface and the inner surface are formed in a same surface of the nozzle body so that the tapered surface and inner surface are continuous and have the same inclination relative to a longitudinal axis of the nozzle body and have a continuously and gradually decreasing diameter toward the nozzle hole.

6 more elements

Dependencies are inferred from the claim text.

Facts

Application: 09/911,714Filed 25 Jul 2001 · division
Priority: 13 Jul 1999
Published: US 2001/0039935 A115 Nov 2001
Granted: 11 Nov 2003
Term ends: Not estimatedThe source records don’t support an estimate.

Classification17 codes

F02M 45/08
With a small initial part , e.g. initial part for partial load and initial and main part for full load: injectors peculiar thereto
F02D 41/3827
Common rail control systems: for diesel engines
F02D 41/403
Multiple injections: with pilot injections
F02M 45/083
Injectors peculiar thereto: having two or more closing springs acting on injection-valve