Injection rate shaping nozzle assembly for a fuel injector

An injection rate shaping nozzle assembly for a fuel injector is provided which includes a closed nozzle valve element and a rate shaping control device including an injection spill circuit for spilling a portion of the fuel to be injected to produce a predetermined time varying change in the flow rate of fuel injected into a combustion chamber. The spill circuit includes a spill passage integrally formed in the nozzle valve element. The rate shaping control may include a spill valve for controlling the spill flow through the spill circuit to create a low injection flow rate followed by a high injection flow rate. The spill passage may communicate with the injector nozzle cavity between injection events or alternatively may be blocked to prevent spill flow between injection events. The rate shaping control device may include a spill accelerating device in the form of a spill chamber formed in the nozzle valve element for creating a rapid increase in the spill flow rate. In another embodiment, the rate shaping device may include a throttling passage integrally formed in the nozzle valve element to vary the rate at which fuel pressure in the nozzle cavity increases so as to vary the flow rate through the injector orifices.

TECHNICAL FIELD 
This invention relates to an improved nozzle assembly for fuel injectors 
which effectively controls the flow rate of fuel injected into the 
combustion chamber of an engine. 
BACKGROUND OF THE INVENTION 
In most fuel supply systems applicable to internal combustion engines, fuel 
injectors are used to direct fuel pulses into the engine combustion 
chamber. Fuel injection into the cylinders of an internal combustion 
engine is most commonly achieved using either a unit injector system or a 
fuel distribution type system. In the unit injector system, fuel is pumped 
from a source by way of a low pressure rotary pump or gear pump to high 
pressure pumps, known as unit injectors, associated with corresponding 
engine cylinders for increasing the fuel pressure while providing a finely 
atomized fuel spray into the combustion chamber. Such unit injectors 
conventionally includes a positive displacement plunger driven by a cam 
which is mounted on an engine driven cam shaft. The fuel distribution type 
system, on the other hand, supplies high pressure fuel to injectors which 
do not pump the fuel but only direct and atomize the fuel spray into the 
combustion chamber. 
A commonly used injector in both the unit and fuel distribution systems is 
a closed-nozzle injector. Closed-nozzle injectors include a nozzle 
assembly having a spring-biased nozzle valve element positioned adjacent 
the nozzle orifice for resisting blow back of exhaust gas into the pumping 
or metering chamber of the injector while allowing fuel to be injected 
into the cylinder. The nozzle valve element also functions to provide a 
deliberate, abrupt end to fuel injection thereby preventing a secondary 
injection which causes unburned hydrocarbons in the exhaust. The nozzle 
valve is positioned in a nozzle cavity and biased by nozzle spring to 
block the nozzle orifices. When the pressure of the fuel within the nozzle 
cavity exceeds the biasing force of the nozzle spring, the nozzle valve 
element moves outwardly to allow fuel to pass through the nozzle orifices. 
Internal combustion engine designers have increasingly come to realize that 
substantially improved fuel supply systems are required in order to meet 
the ever increasing governmental and regulatory requirements of emissions 
abatement and increased fuel economy. It is well known that the level of 
emissions generated by the diesel fuel combustion process can be reduced 
by decreasing the volume of fuel injected during the initial stage of an 
injection event while permitting a subsequent unrestricted injection flow 
rate. As a result, many proposals have been made to provide injection rate 
control devices or modifications in or adjacent to the fuel injector 
nozzle assemblies. One method of controlling the initial rate of fuel 
injection is to spill a portion of the fuel to be injected during the 
injection event. For example, U.S. Pat. Nos. 4,811,715 to Djordjevic et 
at. and 3,747,857 to Fenne each disclose a fuel delivery system for 
supplying fuel to a closed nozzle injector which includes an expandable 
chamber for receiving a portion of the high pressure fuel to be injected. 
The diversion or spilling of injection fuel during the initial portion of 
an injection event decreases the quantity of fuel injected during this 
initial period thus controlling the rate of fuel injection. A subsequent 
unrestricted injection flow rate is achieved when the expandable chamber 
becomes filled causing a dramatic increase in the fuel pressure in the 
nozzle cavity. Therefore these devices rely on the volume of the 
expandable chamber to determine the beginning of the unrestricted flow 
rate. Moreover, the use of a separate expandable chamber device mounted on 
or near an injector increases the costs, size and complexity of the 
injector. U.S. Pat. No. 5,029,568 to Perr discloses a similar injection 
rate control device for an open nozzle injector. 
U.S. Pat. Nos. 4,804,143 to Thomas and 2,959,360 to Nichols disclose other 
fuel injector nozzle assemblies incorporating passages in the nozzle 
assembly for diverting the fuel from the nozzle assembly. The injection 
nozzle unit disclosed in Thomas includes a restricted passage formed in 
the injector adjacent the nozzle valve element for directing fuel from the 
nozzle cavity to a fuel outlet circuit. However, the restricted passage is 
used to maintain fuel flow through the nozzle unit so as to effect 
cooling. The Thomas patent nowhere discusses or suggests the desirability 
of controlling the injection rate. Moreover, the restricted passage is 
closed by the nozzle valve element upon movement from its seated position 
to prevent diverted flow during injection. The fuel injector disclosed in 
Nichols includes a nozzle valve element having an axial passage formed 
therein for diverting fuel from the nozzle cavity into an expansible 
chamber formed in the nozzle valve element. A plunger is positioned in the 
chamber to form a differential surface creating a fuel pressure induced 
seating force on the nozzle valve element to aid in rapidly seating the 
valve element. The Nichols reference does not suggest the desirability of 
controlling the rate of injection. 
U.S. Pat. No. 4,993,926 to Cavanagh discloses a fuel pumping apparatus 
including a piston having a passage formed therein for connecting a 
chamber to an annular groove for spilling fuel during an initial portion 
of an injection event. The piston includes a land which blocks the spill 
of fuel after the initial injection stage to permit the entirety of the 
fuel to be injected into the engine cylinder. However, this device is 
incorporated into a piston pump positioned upstream from an injector. 
Another method of reducing the initial volume of fuel injected during each 
injection event is to reduce the pressure of the fuel delivered to the 
nozzle cavity during the initial stage of injection. For example, U.S. 
Pat. No. 5,020,500 to Kelly discloses a closed nozzle injector including a 
passage formed between the nozzle valve element and the inner surface of 
the nozzle cavity for restricting or throttling fuel flow to the nozzle 
cavity so as to provide rate shaping capability. U.S. Pat. No. 4,258,883 
issued to Hoffman et at. discloses a similar fuel injection nozzle 
including a throttle passage formed between the nozzle valve element and a 
separate control supply valve for restricting fuel flow into the nozzle 
cavity thus limiting the pressure increase in the cavity and the rate of 
injection fuel flow through the injector orifices. However, the devices 
disclosed in both Kelly and Hoffman et at. require extremely close 
manufacturing tolerances which must be carefully controlled to create a 
throttling passage having the precise dimensions necessary to achieve 
effective, predictable rate shaping. As a result, because of the great 
difficulty associated with holding very close manufacturing tolerances, 
these devices greatly increase manufacturing costs. Moreover, this 
tolerance problem makes the production of fuel injectors having 
substantially identical characteristics both technically and economically 
unfeasible. 
U.S. Pat. Nos. 3,669,360 issued to Knight, 3,747,857 issued to Fenne, and 
3,817,456 issued to Schlappkohl all disclose closed nozzle injector 
assemblies including a high pressure delivery passage for directing high 
pressure fuel to the nozzle cavity of the injector and a throttling 
orifice positioned in the delivery passage for creating an initial low 
rate of injection. Moreover, the devices disclosed in Knight and 
Schlappkohl include a valve means operatively connected to the nozzle 
valve element which provides a substantially unrestricted flow of fuel to 
the nozzle cavity upon movement of the nozzle valve element a 
predetermined distance off its seat. 
U.S. Pat. Nos. 3,718,283 issued to Fenne and 4,889,288 issued to Gaskell 
disclose fuel injection nozzle assemblies including other forms of rate 
shaping devices. For example, Fenne '283 uses a multi-plunger and 
multi-spring arrangement to create a two-stage rate shaped injection. The 
Gaskell reference uses a damping chamber filled with a damping fluid for 
restricting the movement of the nozzle valve element. 
Although the systems discussed hereinabove create different stages of 
injection, further improvement is desirable. None of the above discussed 
references disclose a fuel injector incorporating a simple, cost effective 
rate shaping device which minimizes the complexity of the nozzle assembly 
while effectively controlling emissions by controlling the rate of fuel 
injection. 
SUMMARY OF THE INVENTION 
It is an object of the present invention, therefore, to overcome the 
disadvantages of the prior art and to provide an improved nozzle assembly 
for a fuel injector which effectively controls the flow rate of fuel 
injected into the combustion chamber of an engine so as to minimize engine 
emissions. 
It is another object of the present invention to provide a nozzle assembly 
capable of shaping the rate of fuel injection which is also simple and 
inexpensive to manufacture. 
It is yet another object of the present invention to provide a rate shaping 
nozzle assembly for an injector which effectively slows down the rate of 
fuel injection during the initial portion of an injection event while 
subsequently increasing the rate of injection to rapidly achieve a high 
injection pressure. 
It is a further object of the present invention to provide a rate shaping 
nozzle assembly for an injector used in a pump-fine-nozzle fuel system to 
effectively control the rate of injection at each cylinder location. 
It is a still further object of the present invention to provide a rate 
shaping nozzle assembly for an injector which permits rapid closing of the 
nozzle valve element at the end of the injection event to minimize the 
amount of low pressure fuel delivered at the end of the event thereby 
providing a sharper end of injection. 
Still another object of the present invention is to provide a rate shaping 
nozzle assembly for an injector which includes a spill circuit through 
which fuel flow is prevented when the nozzle valve element is closed 
between injection events. 
Yet another object of the present invention is to provide a compact closed 
nozzle assembly for an injector which slows down the opening of the nozzle 
valve element while maintaining high injection pressures and short 
injection durations. 
A further object of the present invention is to provide a rate shaping 
nozzle assembly for an injector which includes a spill circuit and a spill 
valve capable of effectively controlling the flow of spill fuel. 
Another object of the present invention is to provide a rate shaping 
assembly having a spill circuit which effectively control the rate of fuel 
injection while preventing the accumulation of gas or air bubbles in the 
spill circuit. 
These and other objects are achieved by providing a closed nozzle fuel 
injector comprising an injector body containing an injector cavity 
communicating with an injector orifice for discharging fuel into a 
combustion chamber wherein the injector body includes a fuel transfer 
circuit for transferring supply fuel to the orifice and a low pressure 
drain circuit for draining fuel from the injector cavity. A nozzle valve 
element positioned in the injector cavity adjacent the injector orifice is 
movable between an open position in which fuel may flow from the transfer 
circuit through the orifice into the combustion chamber, and a closed 
position in which fuel flow through the injector orifice is blocked. The 
nozzle valve element moves from the closed position to the open position 
and back to the closed position to define an injection event. The injector 
includes a rate shaping control device for producing a predetermined time 
varying change in the flow rate of fuel injected into the combustion 
chamber during the injection event. The rate shaping control device 
includes an injection spill circuit for spilling a portion of the 
injection fuel from the transfer circuit to the low pressure drain circuit 
during the injection event. The spill circuit includes a spill passage 
integrally formed in the nozzle valve element. The rate shaping control 
device may also include a flow limiting orifice positioned along the spill 
circuit for limiting the spill flow through the spill circuit to a 
predetermined maximum spill flow rate. The rate shaping control means may 
also include a spill valve for controlling the spill flow of fuel through 
the spill circuit to create a low injection rate followed by a high 
injection flow rate. A spill valve may be movable into a spill position to 
permit spill fuel flow through the spill circuit to create the low 
injection rate, and into a blocking position to prevent spill flow through 
the spill circuit so as to create a high injection rate following the low 
injection rate. A spill valve means is movable into the spill position 
upon movement of the movable valve element towards the closed position to 
minimize the time necessary for the nozzle valve element to move into the 
closed position. 
The injector may also include a nozzle cavity positioned adjacent the 
injector orifice for housing the nozzle valve element and accumulating 
fuel for injection. The spill passage may include a first end opening into 
the nozzle cavity. The spill circuit may include an outer annular groove 
formed in the nozzle valve element a spaced distance along the element 
from the first end of the spill passage, and also an inner annular groove 
formed in the injector body for registration with the outer annular 
groove. The spill valve may include a movable valve land integrally formed 
on the nozzle valve element adjacent the outer annular groove. The land 
may be movable into a blocking position upon movement of the needle valve 
element from the closed position toward the open position to prevent the 
spill flow of fuel through the spill circuit. 
In another embodiment, the spill valve may include a movable valve land 
integrally formed on the nozzle valve element adjacent the first end of 
the spill passage. The integral valve land is movable into a blocking 
position upon movement of the needle valve from the closed position to the 
open position to prevent spill flow between the nozzle cavity and the 
spill passage. The spill passage may include a transverse passage 
extending transversely through the nozzle valve element and opening into 
the nozzle cavity when the nozzle valve element is in the closed position. 
The injector may include a biasing spring operatively connected to the 
nozzle valve element for biasing the element into the closed position. The 
biasing spring is positioned in a spring cavity forming a portion of the 
spill circuit. 
In the preferred embodiment, the nozzle valve element blocks fuel flow 
through the spill circuit when the valve element is positioned in the 
closed position. The nozzle valve element may include an inner end 
positioned adjacent the injector orifice and an outer end positioned a 
spaced distance from the inner end. The spill passage may include an axial 
passage extending from the inner end along a central longitudinal axis of 
the nozzle valve element toward the outer end. A valve surface may be 
formed on the inner end of the nozzle valve element and is designed to 
engage a corresponding valve seat formed on the injector body adjacent the 
injector orifice when the nozzle valve element is in the closed position 
so as to block fuel flow from the nozzle cavity to the spill passage and 
the injector orifice. The spill circuit may include an annular recess 
formed in the injector body adjacent the nozzle valve element and a 
lateral passage providing fluidic communication between the axial passage 
and the annular recess. The flow limiting orifice may be formed in the 
lateral passage which is formed in the nozzle valve element. The spill 
valve may include an annular step integrally formed on the nozzle valve 
element and an annular valve seat formed on the injector body for sealing 
engagement by the step upon movement of the nozzle valve element into the 
open position to prevent spill flow through the spill circuit. 
The rate shaping control device may include a spill accelerating device 
positioned along the spill circuit for creating a rapid increase in the 
spill flow rate during each injection event. The spill accelerating device 
may include a spill chamber formed in the nozzle valve element for 
receiving spill fuel from the spill passage. The spill chamber includes a 
transverse cross sectional area greater than the transverse cross 
sectional area of the spill passage upstream of the spill chamber so as to 
provide an accumulation chamber for insuring adequate spill flow. The 
spill valve may include an annular valve seat formed on the injector body 
and a movable body valve member having a convex seal surface for 
intermittently engaging the annular valve seat to block the spill flow 
through the spill circuit. The movable valve member may be spherically 
shaped to form a ball-type valve. 
In another embodiment of the present invention, the rate shaping control 
device may include a throttling passage integrally formed in the nozzle 
valve element for restricting the flow of fuel to the nozzle cavity to 
thereby vary the rate at which fuel pressure in the nozzle cavity 
increases. The transfer circuit may include an unrestricted delivery 
passage for permitting unrestricted fuel flow to the nozzle cavity. The 
rate shaping control device may include a flow control valve for 
controlling the flow of fuel through the unrestricted delivery passage. 
The flow control valve includes a valve land integrally formed on the 
nozzle valve element and movable into a blocking position preventing fuel 
flow through the unrestricted delivery passage when the nozzle valve 
element is positioned in the closed position.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Throughout this application, the words "inward", "innermost", "outward", 
and "outermost" will correspond to the directions, respectively, forward 
and away from the point at which fuel from an injector is actually 
injected into the combustion chamber of the engine. The words "outer" and 
"inner" will refer to the portions of the injector or nozzle assembly 
which are, respectively, farthest away and closest to the engine cylinder 
when the injector is operatively mounted on the engine. 
FIGS. 1-7 disclose various embodiments of the rate shaping nozzle assembly 
of the present invention for use in fuel injectors of various types. For 
instance, referring to FIG. 9, there is shown a conventional fuel injector 
10 designed to receive high pressure fuel from a high pressure source (not 
shown) via a delivery line 12. The high pressure source or system 
delivering the high pressure fuel to the injector may be a 
pump-line-nozzle system including one or more high pressure pumps and/or a 
high pressure accumulator and/or a fuel distributor. Injector 10 generally 
includes an injector body 14 formed from an outer barrel 16, an inner 
barrel 18, a nozzle housing 20 and a retainer 22. The inner barrel 18 and 
nozzle housing 20 are held in a compressive buffing relationship in the 
interior of retainer 22 by outer barrel 16. The outer end of retainer 22 
contains internal threads for engaging corresponding external threads on 
the lower end of outer barrel 16 to permit the entire injector body 14 to 
be held together by simple relative rotation of retainer 22 with respect 
to outer barrel 16. 
As is well known, injector body 14 includes an injector cavity indicated 
generally at 24 which includes a spring cavity 26 formed in outer barrel 
16, a nozzle valve element bore 26 formed in the inner barrel 18 and 
nozzle housing 20, and a nozzle cavity 28 formed in the lower end of 
nozzle housing 20. The injector body 14 includes a fuel transfer circuit 
30 comprised of delivery passages 32 and 34 formed in body 14, and 
transfer passages 36 and 38 formed in inner barrel 18 and nozzle housing 
20 respectively, for delivering fuel from delivery line 12 to nozzle 
cavity 28. Injector body 14 also includes one or more injector orifices 40 
fluidically connecting nozzle cavity 28 with a combustion chamber of an 
engine (not shown). 
Fuel injector 10 also includes a nozzle valve element 42 slidably received 
in bore 26 and extending into nozzle cavity 28. A biasing spring 44 
positioned in spring cavity 26 abuts the outer end of nozzle valve element 
42 via a connector button 46 so as to bias the inner end of nozzle valve 
element 42 into a closed position blocking fuel flow through injector 
orifices 40. Injector body 14 also includes a low pressure drain circuit 
including spring cavity 26 and a drain passage 50. Any fuel leaking 
through the slight clearance between nozzle valve element 42 and bore 26 
will be directed to a low pressure drain via cavity 26 and drain passage 
50. 
The rate shaping nozzle assembly of the present invention as described 
hereinbelow can be adapted for use with a variety of injectors and, 
therefore, is not limited to the injector disclosed in FIG. 9. The 
conventional injector of FIG. 9 is merely shown as representative of the 
type of injector in which the present invention may be advantageously 
incorporated. The rate shaping nozzle assembly of the present invention 
can certainly be incorporated into other forms of injectors including a 
unit injector having a high pressure pump plunger incorporated into the 
injector body. 
Now referring to FIGS. 1a and 1b, there is shown the rate shaping nozzle 
assembly of the present invention indicated generally at 52 which includes 
a nozzle housing 54 containing a nozzle bore 56 opening into a nozzle 
cavity 58 at one end. The opposite end of nozzle bore 56 communicates with 
a spring cavity 60 via a through-hole 62 formed in, for example, an inner 
barrel 64. Although not shown, a conventional retainer is used to hold the 
inner barrel and nozzle housing 54 in compressive abutting relationship 
similar to the injector shown in FIG. 9. Received in nozzle bore 56 is a 
nozzle valve element 66 sized to form a close sliding fit with the inside 
surface of bore 56 creating a fluid seal which substantially prevents 
fluid from leaking from the clearance between nozzle valve element 66 and 
the inner surface of bore 56. Nozzle valve element 66 is biased into the 
closed position blocking flow through injector orifices 68 by a biasing 
spring 70 positioned in spring cavity 60. A connector button 72 functions 
as a spring seat and also to transmit the spring force to the outer end of 
nozzle valve element 66. A fuel transfer circuit 74 includes transfer 
passages 76 and 78 formed in the inner barrel and nozzle housing, 
respectively, for delivering high pressure fuel from a high pressure 
source (not shown) to nozzle cavity 58. A low pressure drain circuit 80, 
as discussed with reference to FIG. 9 hereinabove, communicates with 
spring cavity 60 to provide a drain path for fuel leakage into spring 
cavity 60. 
Rate shaping nozzle assembly 52 includes a rate shaping control device 
indicated generally at 82 which includes an injection spill circuit 84 and 
a spill valve 86. Injection spill circuit 84 includes a spill passage 88 
formed integrally in, and extending through, nozzle valve element 66. 
Injection spill circuit 84 also includes an annular recess 90, 
through-hole 62, and spring cavity 60. Spill passage 88 includes an axial 
passage 92 extending from the inner end of nozzle valve element 66, along 
a central longitudinal axis of nozzle valve element 66, and terminating 
prior to the outer end of valve element 66. Spill passage 88 also includes 
a lateral passage 94 extending from the outer end of axial passage 92 to 
communicate with annular recess 90. Annular recess 90 communicates with 
spring cavity 60 via an annular clearance 96 formed between the outer end 
of valve element 66 and through-hole 62. Lateral passage 94 is sized to 
function as a flow limiting orifice so as to throttle the flow through 
injection spill circuit 84. Axial passage 92 and lateral passage 94 may be 
formed by drilling or electrical discharge machining the passages into a 
fully hardened and finished nozzle element. 
Spill valve 86 includes an annular step 98 formed on nozzle valve element 
66 adjacent annular recess 90. Spill valve 86 also includes an annular 
valve seat 100 formed opposite step 98 on inner barrel 64. When nozzle 
valve element 66 is in a closed position as shown in FIG. 1a blocking fuel 
flow through injector orifices 68, annular step 98 is positioned a spaced 
distance from annular valve seat 100 to provide a spill flow path from 
annular recess 90 to spring cavity 60 via clearance gap 96. However, 
during an injection event, when nozzle valve element 66 moves to a fully 
open position shown in FIG. 1b, annular step 98 sealingly engages annular 
valve seat 100 to prevent spill flow between annular recess 90 and spring 
cavity 60. Spill passage 88 is formed in nozzle valve element 66 so that 
the conventional valve arrangement formed on the inner end of element 66 
can be used as a spill valve. Specifically, the inner end of nozzle valve 
element 66 includes a valve surface 102 for sealingly engaging a valve 
seat 104 formed on the inner surface of nozzle cavity 58 upstream of 
injector orifices 68. The inner end of axial passage 92 opens relative to 
valve seat 104 so that nozzle valve element 66 blocks fuel flow from 
nozzle cavity 58 to axial passage 92 when nozzle valve element 66 is in 
the closed position against valve seat 104. As a result, no spill fuel 
flows through spill passage 88 between injection events. 
During operation, between injection events, nozzle valve element 66 is 
positioned in the closed position as shown in FIG. 1a blocking flow 
through injector orifices 68 and injection spill circuit 84. At the start 
of an injection event, high pressure fuel is delivered from fuel transfer 
circuit 74 to nozzle cavity 58. When the pressure of the fuel in nozzle 
cavity 58 reaches a predetermined maximum necessary to overcome the 
biasing force of spring 70, nozzle valve element 66 begins to lift off 
valve seat 104 permitting fuel flow from nozzle cavity 58 through fuel 
injector orifices 68 into the combustion chamber of an engine. Fuel also 
spills into axial passage 92 traveling outwardly through lateral passage 
94 into annular recess 90. During the initial outward movement of the 
nozzle valve element 66, annular step 98 is still positioned a spaced 
distance from annular valve seat 100. As a result, fuel flowing into 
annular recess 90 is permitted to spill through clearance gap 96 into 
spring cavity 60 and on to the low pressure drain (not shown) connected to 
spring cavity 60. 
Therefore, with the present rate shaping nozzle assembly 52, a portion of 
the fuel normally flowing through injector orifices 68 is instead directed 
into spill passage 88. This splitting of the fuel flow into an injection 
flow and a spill flow during the initial portion of the injection event 
creates a reduced or low injection rate as represented by Stage I in FIG. 
2. The size of the orifice formed in lateral passage 94 or, alternatively, 
the diameter of lateral passage 94, determines the maximum spill rate to 
the low pressure drain and thus controls the injection rate through 
orifices 68. Further outward movement of nozzle valve element 66 into a 
fully opened position as shown in FIG. 1b, causes annular step 98 to 
sealingly engage annular valve seat 100 blocking fluidic communication 
between annular recess 90 and annular clearance 96. Thus, once nozzle 
valve element 66 moves into the fully opened position, spill flow through 
injection spill circuit 84 is prevented thereby permitting full fuel flow 
through injector orifices 68. As indicated by Stage II in FIG. 2, blockage 
of the spill flow causes the injection flow rate through injector orifices 
68 to rapidly increase. 
At the end of the injection event, when the delivery of high pressure fuel 
to nozzle cavity 58 has ceased, nozzle valve element 66 begins to move 
inwardly toward the closed position shown in FIG. 1a. During this inward 
movement, annular step 98 moves away from valve seat 100 permitting spill 
flow of pressurized fuel from nozzle cavity 58 through injection spill 
circuit 84. This creation of an additional drain or spill path during the 
last portion of the injection event causes a rapid decrease in the 
injection flow rate through orifices 68 since a portion of the fuel is 
directed through spill circuit 84. This end of injection spill 
advantageously creates a sharper end to the injection event. 
Referring now to FIGS. 3a-3d, alternative embodiments of the nozzle valve 
element used in rate shaping nozzle assembly 52 of FIGS. 1a and 1b are 
shown. It has been found that spill flow through axial passage 92 may be 
inadequate under certain conditions given the short duration of an 
injection event and the minimal size of axial passage 92. The embodiments 
shown in FIGS. 3a-3d all include means for accelerating the spill flow 
through axial passage 92 so as to insure sufficient spill flow necessary 
to reduce the injection flow rate through orifices 68. 
As shown in FIG. 3a, a spill accelerating device 106 may include a second 
axial passage 107 having a larger diameter than axial passage 92. The 
axial passages may be formed by electrical discharge machining from the 
outer end of nozzle valve element 66. The larger diameter of second axial 
passage 107 results in a larger cross sectional flow area and thus a 
larger volume for receiving spill fuel from axial passage 92. 
Consequently, this combination of axial passages 92 and 107 creates less 
impediment to spill flow than the embodiment of FIG. 1a. The outer end of 
second axial passage 107 may be closed with a plug 108 securely positioned 
in the end of second axial passage 107 by, for example, an interference 
fit, after heat treating nozzle valve element 66. Alternatively, plug 108 
could be positioned in second axial passage 107 prior to heat treatment to 
allow the heat treatment process to create a secure fit. 
FIG. 3b discloses another embodiment of the nozzle valve element 66 
including a spill accelerating device 110 including a relatively large 
volume spill chamber 112 positioned at the outer end of axial passage 92 
between lateral passage 94 and axial passage 92. Spill chamber 112 
functions similarly to second axial passage 107 to increase the spill flow 
during the initial portion of the injection event so as to insure adequate 
spill flow to reduce the injection flow rate through orifices 68 by an 
amount necessary to enhance combustion and minimize emissions. 
FIG. 3c discloses yet another embodiment of nozzle valve element 66 
incorporating a spill accelerating device 114 in the form of two cross 
drillings, 116, 118 extending transversely through nozzle valve element 66 
and communicating with axial passage 92. The insertion of nozzle valve 
element 66 into nozzle housing 54 permits nozzle bore 56 to close the 
openings of drillings 116 and 118 so as to seal the injection spill 
circuit. Cross drillings 116 and 118 function as spill chambers similar to 
spill chamber 112 of FIG. 3b. In addition, it has been found that spill 
chambers or drillings 116, 118 effectively minimize the formation of air 
or gas pockets resulting from the accumulation of gas in the spill 
circuit. Such gas pockets have been found to disadvantageously reduce the 
flow through axial passage 92 impairing the performance of rate shaping 
nozzle assembly 52. 
FIG. 3d discloses yet another embodiment of nozzle valve element 66 
including a spill accelerating device 120 comprised of four angled 
drillings 121-124 communicating with axial passage 92 and opening onto the 
outer surface of nozzle valve element 92. Passages 123 and 124 are angled 
to receive spill flow from axial passage 92 and direct the flow outwardly 
into passages 122 and 121 respectively. Passages 122 and 121 angle 
inwardly toward the central axis of nozzle valve element 66 to direct the 
spill flow back into axial passage 92. Since passages 121-124 communicate 
with nozzle bore 56, this embodiment also effectively permits the 
formation of gas pockets along axial passage 92. 
The spill flow rate, and therefore the injection flow rate, can be 
controlled by forming the spill passages in the nozzle valve element with 
a specific total volume necessary to create the desired spill flow rate. 
The easiest and most practical manner in which to establish the total 
spill volume is to control the size of the spill accelerating device, i.e. 
axial passage 107, spill chamber 112, cross drillings 116, 118 and angled 
drillings 121-124. The Table shows volumetric values for each of the spill 
accelerating devices which have been found to produce spill flow rates 
particularly advantageous in creating optimum injection rate shaping. 
TABLE 
__________________________________________________________________________ 
NOZZLE VALVE EMBODIMENT 
VOLUME (mm.sup.3) 
FIG. 3a 
Design 
Design 
SPILL PASSAGE 
FIGS. 1a & 1b 
No. 1 
No. 2 
FIG. 3b 
FIG. 3c 
FIG. 3d 
__________________________________________________________________________ 
AXIAL PASSAGE 
8.310 2.838 
1.013 
6.283 
7.702 
8.310 
LATERAL 0.557 0.507 
0.507 
0.405 
0.557 
0.557 
PASSAGE 
SPILL N/A 17.846 
22.656 
47.451 
14.137 
14.840 
ACCELERATING 
DEVICE 
TOTAL VOLUME 
8.867 21.190 
24.176 
54.140 
22.396 
23.727 
__________________________________________________________________________ 
FIGS. 4a and 4b represent another embodiment of the rate shaping nozzle 
assembly of the present invention which includes a nozzle valve element 
150 having an integral spill passage 152 formed therein which remains in 
fluidic communication with nozzle cavity 58 when nozzle valve element 150 
is in the closed position as shown in FIG. 4a. Spill passage 152 includes 
a transverse passage 154 extending through nozzle valve element 150 and 
positioned along the axial length of element 150 so as to communicate with 
nozzle cavity 58 at both ends when valve element 150 is in the closed 
position. Spill passage 152 also includes an axial spill passage 156 
extending from transverse spill passage 154 outwardly through nozzle valve 
element 150 to communicate with annular recess 90. A spill valve device 
158 for controlling the flow of spill fuel through transverse spill 
passage 154 includes an annular valve land 160 formed on nozzle valve 
element 150 adjacent to, and inward of, transverse passage 154. During the 
initial movement of nozzle valve element 150 toward the open position, 
injection fuel is spilled from nozzle cavity 58 to low pressure drain 80 
via transverse passage 154, axial passage 156 and annular recess 90 
similar to the embodiment of FIGS. 1a and 1b. At a predetermined point 
during the movement of nozzle valve element 150 towards the open position, 
valve land 160 blocks communication between transverse passage 154 and 
nozzle cavity 58 stopping the spill flow of fuel. When nozzle valve 
element 150 moves toward the closed position during the last portion of 
the injection event, valve land 160 moves to permit fluidic communication 
between nozzle cavity 58 and transverse passage 154 thereby relieving 
pressure in nozzle cavity 58 to cause a sharp end to injection. The 
resulting injection rate shape during the injection event is similar to 
that shown in FIG. 2. 
FIGS. 5a and 5b disclose yet another embodiment of the spill-type rate 
shaping nozzle assembly of the present invention which includes a fuel 
injector 170 including an outer barrel 172, a nozzle housing 174, and an 
inner barrel 176 positioned in compressive abutting relationship between 
outer barrel 172 and nozzle housing 174. The present embodiment is similar 
to the previous embodiment of FIGS. 4a and 4b in that nozzle cavity 58 
fluidically communicates with a low pressure drain via a spill passage 178 
formed integrally in a nozzle valve element 180. Moreover, the present 
embodiment includes a spill valve 182 including a movable valve land 184 
integrally formed on nozzle valve element 180 which moves outwardly during 
movement of nozzle valve element 180 toward the open position, to block 
flow through spill passage 178. However, spill passage 178 includes a 
diagonal passage 186 extending transversely through nozzle valve element 
180 outwardly from nozzle cavity 58. Diagonal passage 186 continuously 
communicates at an innermost end with nozzle cavity 58 and at an outermost 
end with an inner annular groove 188 formed in the outer surface of nozzle 
valve element 180 a spaced distance outwardly from nozzle cavity 58. An 
outer annular groove 190 formed in nozzle housing 174 registers with inner 
annular groove 188 when nozzle valve element 180 is positioned in the 
closed position as shown in FIG. 5a. A low pressure drain circuit 192 
includes a first low pressure drain passage 194 formed in nozzle housing 
174 and extending from outer annular groove 190. A second low pressure 
drain passage 196 extends through inner barrel 176 so as to fluidically 
connect low pressure drain passage 194 with a spring cavity 198 formed in 
both outer barrel 172 and inner barrel 176. Spring cavity 198 is connected 
to a low pressure drain (not shown) to form low pressure drain circuit 
192. Second low pressure drain passage 196 includes a throttling orifice 
200 sized to restrict the spill flow of fuel to a predetermined maximum 
flow rate. Similar to the previous embodiment, the present rate shaping 
control device permits spill flow to the low pressure drain circuit 192 
when the nozzle valve element is in the closed position as shown in FIG. 
5a and during a predetermined time period during the initial lift of 
nozzle valve element 180 from the closed to the open position of FIG. 5b. 
After nozzle valve element 180 has lifted a predetermined distance off its 
seat towards the open position, movable valve land 184 moves into a 
blocking position preventing flow through spill passage 178 thus causing 
full flow of injection fuel through orifices 68. 
Referring now to FIGS. 6a and 6b, another embodiment of the present 
invention is shown which includes a rate shaping control device which, 
unlike the previous embodiments, does not spill fuel to be injected but 
instead restricts the flow of fuel to nozzle cavity 58 during the initial 
portion of the injection event. Specifically, a throttling passage 210 
containing a throttling orifice 211 extends through nozzle valve element 
212 to fluidically connect nozzle cavity 58 with an annular groove 214 
formed in nozzle valve element 212. An annular land 216 formed on nozzle 
valve element 212 between annular groove 214 and nozzle cavity 58 forms a 
close sliding fit with the inner surface of nozzle housing 218 to form a 
fluid seal between nozzle valve element 212 and nozzle housing 218 when 
nozzle valve element 212 is in the closed position as shown in FIG. 6a. An 
unrestricted delivery passage indicated generally at 219 includes grooves 
220 formed in the outer surface of nozzle valve element 212 and equally 
spaced around the circumference of nozzle valve element 212. 
When nozzle valve element 212 is in the closed position as shown in FIG. 
6a, annular land 216 blocks fuel flow from delivery passage 222 through 
grooves 220. As a result, supply fuel may only flow from delivery passage 
222 into the nozzle cavity 58 via annular groove 214 and throttling 
passage 210. Once fuel pressure in nozzle cavity 58 reaches a 
predetermined level, nozzle valve element 212 begins to move outwardly off 
its seat to permit fuel to be injected through injector orifices 68. 
During this initial movement of nozzle valve element 212, throttling 
passage 210 functions to limit the rate of increase in injection pressure 
within nozzle cavity 58 thus limiting the injection flow through injector 
orifices 68 while controlling the lifting speed of nozzle valve element 
212. Once nozzle valve element 212 lifts a predetermined distance from its 
seat, annular land 216 moves into a blocking position preventing fuel flow 
through throttling passage 210. As annular land 216 moves into the 
blocking position, grooves 220 are moved into fluidic communication with 
delivery passage 222 permitting supply fuel flow through grooves 220 into 
nozzle cavity 58. Grooves 220 are sized to permit full, unrestricted fuel 
flow into nozzle cavity 58 thereby permitting the injection pressure 
within nozzle cavity 58 to increase at a predetermined unrestricted rate. 
In this manner, throttling passage 210 controls the rate of increase in 
the pressure of the fuel in nozzle cavity 58 so as to control the 
injection rate of fuel through injector orifices 68. 
As shown in FIG. 7, the present rate shaping control device throttles the 
flow of fuel into nozzle cavity 58 so as to create a lower rate of fuel 
injection through orifices 68 during the initial portion of an injection 
event (indicated by dashed lines in FIG. 7) as compared to the initial 
injection rate shape of a conventional nozzle element (indicated by solid 
lines), such as the nozzle of FIG. 9. 
FIG. 8 illustrates yet another embodiment of the present invention which 
includes a spill-type rate shaping control device having a spill valve 
which effectively controls the flow of fuel through the spill circuit. A 
fuel transfer circuit 230 includes delivery passages 232 and 234 extending 
through injector barrel 236 and nozzle housing 238, respectively. A spill 
circuit 240 includes a spill passage 242 extending from delivery passage 
234 through nozzle housing 238 to communicate with a spill valve cavity 
234 formed in nozzle housing 238. Spill passage 242 includes a throttling 
orifice 246 for limiting the spill flow to a predetermined maximum flow 
rate. Spill valve cavity 244 fluidically communicates with spring cavity 
248 via an opening 250 formed in the inner end of injector barrel 236. A 
connector button 252 functions as a spring seat for bias spring 254 and 
extends through opening 250. A spill valve 256 includes a spherical ball 
258 positioned in spill valve cavity 244 and rigidly connected to the 
innermost end of connector button 252. The innermost end of spherical ball 
258 abuts the outermost end of a nozzle valve element 260 permitting the 
spring force of spring 254 to bias valve element 260 into the closed 
position as shown. Spill valve 256 also includes an annular valve seat 
formed on injector barrel 236 around opening 250 for engagement by 
spherical ball 258. The outermost surface of spherical ball 258 includes a 
convex seal surface 264 for engaging annular valve seat 262 when the 
nozzle valve element 260 moves into the open position as represented by 
dashed lines in FIG. 8. Spill valve 256 operates similar to the spill 
valve 86 of FIGS. 1a and 1b to block the spill flow through spill circuit 
240 upon movement of nozzle valve element 260 into the open position. 
However, convex seal surface 264 of spherical ball 258 insures that an 
effective fluid seal is formed with annular valve seat 262 so as to 
prevent leakage by valve seat 262 thereby insuring supply fuel delivery to 
nozzle cavity 266 without undesired spill flow. An inner spring 268, 
positioned around nozzle valve element 260 in nozzle cavity 266, is used 
to maintain nozzle valve element 260 in the open position against 
spherical ball 258 when the bias forces acting in opposite directions on 
nozzle valve element 260 are equal. Although the present convex seal 
surface 264 is shown incorporated in a rate shaping device including a 
spill passage formed in a nozzle housing, spherical ball 258 and convex 
seal surface 264 could be incorporated into the embodiments of FIGS. 1a 
and 1b. 
INDUSTRIAL APPLICABILITY 
It is understood that the present invention is applicable to all internal 
combustion engines utilizing a fuel injection system and to all closed 
nozzle injectors including unit injectors. This invention is particularly 
applicable to diesel engines which require accurate fuel injection rate 
control by a simple rate control device in order to minimize emissions. 
Such internal combustion engines including a fuel injector in accordance 
with the present invention can be widely used in all industrial fields and 
non-commercial applications, including trucks, passenger cars, industrial 
equipment, stationary power plant and others.