US 5,632,444 A · Fuel injection rate shaping apparatus for a unit injector

Abstract

A multipiece fuel pump plunger assembly for controlling the fuel injection rate and delivery during the initial injection portion of a fuel injection cycle for an internal combustion engine. The injector includes a two piece plunger assembly including a plunger and a plunger sleeve. The plunger having a small predetermined diameter and being slidably positioned within a plunger sleeve having a diameter greater than the diameter of the plunger. The multipiece plunger is advantageous because it allows for shaping of the rate of fuel injected into the combustion process thereby reducing the excess fuel flow in the early portion of the injection cycle. Elimination of the excess fuel flow results in lower oxides of nitrogen and particulate exhaust emission levels and less engine noise.

Claims12

Dependent claims

A fluid unit injector rate shaping apparatus, comprising:

a housing having a longitudinal bore;
a plunger sleeve having a longitudinal extending bore and being movable within and relative to said housing bore, said housing, said housing bore and said plunger sleeve defining a fluid pump chamber, said plunger sleeve being movable a preselected distance into the pump chamber;
a plunger slidably positioned in said plunger sleeve bore and being movable a preselected distance into the pump chamber, said plunger having an actuating end distally disposed relative to said pump chamber;
first means for moving said plunger in a direction toward the fluid pump chamber, said first means including a moveable member engageable with said actuating end;
second means for moving said plunger sleeve in a direction toward the fluid pump chamber during movement of said plunger.

2 more elements

In an apparatus for injection rate shaping for a hydraulically-actuated fluid unit injector, said injector having a barrel, an intensifier piston, a piston cavity, a plunger spring, a washer retainer, and a ring retainer, said intensifier piston having a first and second end portions, said plunger spring being positioned within said piston cavity and interposed between said washer retainer and said barrel, each of said barrel, said plunger spring, and said washer retainer having a longitudinal central bore, the improvement comprising:

a plunger sleeve having a first end portion, a second end portion, a longitudinal extending bore, and an outwardly extending stop positioned at said first end portion, a preselected length "l" and being slidably positioned and moveable relative to the barrel, the plunger spring and the intensifier piston;
a plunger having first and second end portions, an outwardly extending stop positioned at said first end portion, a diameter of a size suitable for insertion into the bore of said plunger sleeve, and being of a preselected length "L" greater than said plunger sleeve length "l" and being slidably positioned in the bore of said plunger sleeve and moveable relative to the barrel, the plunger sleeve, and the plunger spring;
and
means of fixedly connecting said second end portion of said plunger to the washer retainer.

1 more element

Dependencies are inferred from the claim text.

Fuel injection rate shaping apparatus for a unit injector

Life of this patent

Fuel injection rate shaping apparatus for a unit injector

Life of this patent

Abstract

Claims12