Internal-combustion engines – Charge forming device – Fuel injection system
Reexamination Certificate
2000-10-23
2002-04-23
Moulis, Thomas N. (Department: 3747)
Internal-combustion engines
Charge forming device
Fuel injection system
C123S468000, C123S469000, C123S470000
Reexamination Certificate
active
06374806
ABSTRACT:
TECHNICAL FIELD
The present invention concerns fluid rail assemblies for fuel injected internal combustion engines. More particularly, the present invention relates to a conveyance of a fluid from a fluid rail assembly to a hydraulically actuated, electronically controlled fuel injector.
BACKGROUND OF THE INVENTION
Certain fuel injectors can be described as hydraulically actuated, electronically controlled. Hydraulic actuation of the fuel injector is preferably effected by engine oil at an elevated pressure. It should be understood that other fluids self contained in the vehicle powered by the internal combustion engine could also be used for hydraulic actuation of the fuel injector, including brake fluid, power steering fluid, or the like.
An exemplary fuel injector of this type is depicted generally in prior art
FIG. 1
at
200
. A hydraulically-actuated, electronically-controlled, unit injector (HEUI), of the type described in U.S. Pat. No. 5,181,494 and in SAE Technical Paper Series 930270
, HEUI—A New Direction for Diesel Engine Fuel Systems
, S. F. Glassey, at al, Mar. 1-5, 1993, which are incorporated herein by reference, as depicted in prior art FIG.
1
. HEUI
200
consists of four main components: (1) control valve
202
; (2) intensifier
204
; (3) nozzle
206
; and (4) injector housing
208
.
The purpose of the control valve
202
is to initiate and end the injection process. Control valve
202
is comprised of a poppet valve
210
, electric control
212
having an armature and solenoid. High pressure actuating oil is supplied to the valve's lower seat
214
through oil passageway
216
. To begin injection, the solenoid of the electric control
212
is energized moving the poppet valve
210
upward the lower seat
214
to the upper seat
218
. This action admits high pressure oil to the spring cavity
220
and the passage
222
to the intensifier
204
. Injection continues until the electric control
212
solenoid is de-energized and the poppet
210
moves from the upper seat
218
to lower seat
214
. Actuating oil and fuel pressure decrease as spent actuating oil is ejected from the injector
200
through the open upper seat oil discharge
224
to the valve cover area of the internal combustion engine, which is at ambient pressure.
The middle segment of the injector
200
consists of the hydraulic intensifier piston
236
, the plunger
228
, fuel chamber
230
, and the plunger return spring
232
.
Intensification of the fuel pressure to desired injection pressure levels is accomplished by the ratio of areas between the upper surface
234
of the intensifier piston
236
and the lower surface
238
of the plunger
228
, typically about 7:1. The intensification ratio can be tailored to achieve desired injection characteristics. Fuel is admitted to chamber
230
through passageway
240
past check valve
242
from an external fuel supply.
Injection begins as high pressure actuating oil is supplied to the upper surface
234
of the intensifier piston
236
via passageway
222
. As the piston
236
and the plunger
228
move downward, the pressure of the fuel in the chamber
230
below the plunger
228
rises. High pressure fuel then flows in passageway
244
past check valve
246
to act upward on needle valve surface
248
. The upward force opens needle valve
250
and fuel is discharged from orifice
252
against the bias of return spring
256
. The piston
236
continues to move downward until the electric control
212
solenoid is de-energized, causing the poppet valve
210
to return to the lower seat
214
under the force of spring
220
, blocking oil flow. The plunger return spring
232
then returns the piston
236
and plunger
228
to their initial upward inactive positions as depicted in FIG.
4
. As the plunger
228
returns, the plunger
228
draws replenishing fuel into the fuel chamber
230
across ball check valve
242
.
The nozzle
206
is typical of other diesel fuel system nozzles. The valve-closed-orifice style is shown, although a mini-sac version of the tip is also available. Fuel is supplied to the nozzle orifice
252
through internal passages. As fuel pressure increases, the nozzle needle
250
lifts from the lower seat
254
(as described below) allowing injection to occur. As fuel pressure decreases at the end of injection, the spring
256
returns the needle
250
to its closed position seated on the lower seat
254
.
The fuel injector
200
uses the hydraulic energy of pressurized actuating fluid, in this case engine oil, to cause injection. The pressure of the incoming oil controls the downward speed of the intensifier piston
236
and plunger
228
movement, and therefore, the rate of fuel injection. The amount of fuel injected is determined by the duration of a signal keeping the electric control
212
solenoid energized. As long as the solenoid is energized and the poppet valve
210
is off its seat, the actuating fluid continues to push down the intensifier piston
236
and plunger
228
until the intensifier piston
236
reaches the bottom of its bore.
A similar hydraulically-actuated unit injector
200
is described in SAE paper No. 1999-01-0196, “Application of Digital Valve Technology to Diesel Fuel Injection” and U.S. Pat. No. 5,720,261. In this injector, the poppet control valve
202
of the HEUI injector has been replaced by a spool type digital control valve which is controlled by two solenoid coils, the valve spool being the armature.
In either case, there is a need for delivery of the high pressure volume of actuating fluid to the fuel injector in order to effect the fuel injection event. Actuating fluid delivery must be accomplished while allowing for assembly and part tolerance stack-ups and relative mechanical motion existing between the apparatus delivering the actuating fluid and the fuel injector. Tolerance stack-ups impose a considerable constraint on the design of any apparatus for delivering actuating fluid to a fuel injector. The injector, cylinder head, actuating fluid rail, and the connecting mechanism between the rail and the injector all have tolerances associated with them. Further, the connection between the rail and the injector must accommodate mechanical and thermal motion between the rail and the injector, the hydraulic load tolerance of the injector and the performance requirements of the injector. A desirable delivery mechanism is one that imposes no stress forces on the injector as a result of the aforementioned tolerances and of the aforementioned relative motion. The delivery mechanism should additionally be easily connectable to the injector.
U.S. Pat. No. 4,996,962, issued Mar. 5, 1991, discloses a fuel delivery rail assembly. The '962 assembly uses sockets affixed to the tops of the fuel injectors. Plastic rail tubes extending between the sockets provide flexible engagements. The '962 patent asserts that with such flexible engagements there is no need of strict limitation about a dimensional accuracy or geometrical orientation of the parts. It should be noted that while it is claimed that the flexible plastic rail tubes solve some of the problems sought to be solved by the present invention, there is no structure or teaching in the '962 patent that relates to the present invention.
SUMMARY OF THE INVENTION
The actuating fluid delivery system of the present invention substantially meets the aforementioned needs of the industry. The connector assembly of the present invention that extends between the rail assembly and the fuel injector accommodates the aforementioned tolerances by being movable in three dimensions. Further, after installation, relative motion existing between the rail assembly and the fuel injector is further accommodated by the ability of the connector assembly to accommodate such motion by being shiftable in three dimensions and is rotatable at is least about a longitudinal axis, such rotation setting up the condition under which shifting in a plane disposed orthogonally with respect to the longitudinal axis may occur. The shifting does not occur unless there
Keeley Philip D.
Serio John A.
Seymour, II Kenneth R.
Yager James H.
Zielke Martin R.
Calfa Jeffrey P.
Hernandez Gilberto
International Truck and Engine Corp.
Moulis Thomas N.
Sullivan Dennis Kelly
LandOfFree
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