Internal-combustion engines – Charge forming device – Fuel injection system
Reexamination Certificate
1999-04-20
2001-08-28
Yuen, Henry C. (Department: 3747)
Internal-combustion engines
Charge forming device
Fuel injection system
C123S458000
Reexamination Certificate
active
06279539
ABSTRACT:
TECHNICAL FIELD
The present invention applies generally to hydraulically actuated fuel injectors and more specifically to hydraulically actuated fuel injectors with features to aid in performance at cold start.
BACKGROUND ART
Fuel injectors which utilize engine lubricating oil as actuation fluid are sometimes subject to performance diminutions at cold start due to viscous oil flowing into an armature cavity defined by the injector body and a solenoid. During a cold start, the highly viscous cold oil can inhibit the movement of the armature. In turn, injector performance can be adversely affected by the slowing down and/or restricted movement of the armature. One method for dealing with this problem is taught in U.S. Pat. No. 5,375,576 to Ausman et al. and involved positioning an o-ring seal in the fuel injector to prevent viscous oil from flowing into the armature cavity. Additionally, the poppet valve and sleeve in these previous fuel injectors were machined to tight clearances to aid in prevention of viscous oil flow into the armature cavity. By preventing the flow of cold oil into the armature cavity, the performance problems associated with viscous oil surrounding the armature during cold start can be avoided. Although the sealing and clearance solutions of Ausman have worked well for years, geometrical and spatial constraints do not always allow for the implementation and use of these solutions. Thus, in some fuel injectors a different solution must be found to alleviate the problems associated with cold start.
The present invention is directed to overcoming one or more of the problems described above and to improving fuel injector performance at cold start.
SUMMARY OF THE INVENTION
A hydraulically actuated fuel injector includes an injector body which has an outer surface. An armature cavity is defined by the injector body and a solenoid, which includes a coil. The solenoid also includes an armature which is positioned within the armature cavity. Attached to the armature and positioned in the injector body is a valve member that defines a centerline. A plurality of evacuation passages are defined by the injector body and extend from the armature cavity to the outer surface. The armature and the evacuation passages are positioned on opposite sides of a plane that is oriented perpendicular to the centerline.
REFERENCES:
patent: 3758071 (1973-09-01), Anderson
patent: 4392612 (1983-07-01), Deckard
patent: 4470545 (1984-09-01), Deckard
patent: 4540122 (1985-09-01), Teerman
patent: 4572433 (1986-02-01), Deckard
patent: 4618095 (1986-10-01), Spoolstra
patent: 4883252 (1989-11-01), Mesenich
patent: 5011113 (1991-04-01), Stobbs
patent: 5143291 (1992-09-01), Grinsteiner
patent: 5213083 (1993-05-01), Glassey
patent: 5234024 (1993-08-01), Stoltman
patent: 5375576 (1994-12-01), Ausman
patent: 5517972 (1996-05-01), Stockner
patent: WO 93/07382 (1993-04-01), None
Graves Jeffrey D.
Lehman Martin A.
Caterpillar Inc.
Gimie Mahmoud
Liell & McNeil
Yuen Henry C.
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