Orifice plunger valve fuel injector

An orifice plunger valve fuel injector is provided with a nozzle body having a bore extending from one end thereof, a plunger valve being slidably mounted and closely fitted within the bore of the nozzle body, the end of the plunger valve adjacent said one end of said nozzle body being provided with radially extending spray tip holes therein which are supplied with pressurized fuel through an axial passage in the plunger valve in communication at one end with the spray tip holes and at its other end, intermediate the ends of the plunger valve, with at least one radial passage in communication with an inlet fuel passage means in the nozzle body supplied with fuel under pressure through a one-way valve from a source of fuel under pressure, a retractor spring being positioned in the nozzle body and operatively connected with the plunger valve to normally bias the plunger valve into a retracted position within the bore of the nozzle body whereby the spray tip holes are closed off by the bore wall of the nozzle body, when the pressure of fuel in said fuel passage is less than the pressure required acting on the differential area of the plunger valve to effect its axial displacement in the bore of the nozzle body, against the force of the retractor spring, to a position where the spray tip holes are uncovered to effect fuel injection. The spray holes will be uncovered only sufficiently to maintain the predetermined fuel injection pressure at the orifices formed by the spray tip holes in the plunger valve and the lower end of the nozzle body.

This invention relates to a device for injecting fuel into the cylinders of 
an internal combustion engine and, in particular, to a fuel injector or 
fuel injection nozzle for such a device. 
Fuel injectors or fuel injection nozzles whether used as part of a unit 
injector or as part of a pump and nozzle system are normally of the needle 
valve controlled type that includes a nozzle body having a spray tip at 
one end thereof with spray orifices therein in communication with an axial 
passage in the nozzle body supplied with fuel under pressure, flow of fuel 
through the passage to the spray orifices being controlled by a needle 
valve having a seat at one end thereof adapted to cooperate with a seat in 
the nozzle body upstream of the spray orifices, the needle valve being 
normally biased to a closed position by a closing spring. In this type 
fuel injector, there is normally at least some so-called "sac volume" when 
the needle valve is closed between its seat and the discharge end of the 
spray orifices, which sac volume contains raw fuel after the injection 
cycle has been terminated that can then dribble into the cylinder of the 
engine with which the fuel injector is associated. 
It is also well known in the art of fuel injection that the needle valve on 
both opening and closing will have an area less than that of the spray 
orifices. This causes the very first fuel and the very last fuel injected 
to be poorly atomized and causes dribble. And further, in those nozzles 
where the needle seat is formed over the spray orifices for the purpose of 
preventing the "sac volume" from escaping, there is still raw fuel in the 
spray orifices which cannot be prevented from entering the combustion 
chamber of the associated engine. This invention eliminates that 
possibility. 
In addition, in these prior art needle valve type injectors or nozzles, the 
force of the closing spring must be sufficient to effect seating of the 
needle valve against cylinder pressure which acts to hold the needle valve 
open. 
It is therefore a primary object of this invention to provide an improved 
fuel injector or injection nozzle of the type wherein the fuel delivery is 
controlled by a piston or plunger type valve operable in response to a 
predetermined fuel injection pressure, the discharge spray orifices of the 
device being incorporated in the piston or plunger valve. 
Another object of this invention is to provide an improved fuel injector or 
injection nozzle of the type wherein the fuel delivery is controlled by a 
piston or plunger type valve with the fuel injection pressure applied only 
to the differential area of the valve of the injector or injection nozzle. 
A further object of this invention is to provide an improved fuel injector 
or injection nozzle that is of simple, but rugged construction, that is 
easily manufactured and can be easily serviced. 
These and other objects of the invention are obtained by a fuel injector 
having a nozzle body with a stepped bore therein defining an annular valve 
sleeve wall extending from one end of the nozzle body and a spring chamber 
closed at one end within the opposite end of the nozzle body, a plunger 
valve having a fuel passage therein which extends to adjacent one end 
thereof that is in communication with radial spray orifices extending 
through the wall of the plunger valve adjacent this one end, the plunger 
valve being reciprocally mounted in the stepped bore of the nozzle body 
for movement between a retracted position in which the spray orifices are 
closed off by the valve sleeve wall and an extended position in which the 
end of the valve body having the spray orifices therein projects axially 
outward of the valve sleeve wall, a spring being positioned in the spring 
chamber and connected to the plunger valve to normally bias the plunger 
valve to the retracted position and, a valve controlled fuel passage means 
in the nozzle body adapted to be connected at one end to a source of fuel 
at high pressure and at its opposite end, the passage means is in fluid 
flow communication with the fuel passage in the plunger valve.

Referring now in detail to the drawings and, in particular to FIG. 1, there 
is shown a unit fuel pump-injector, the upper portion of which is 
conventional and comprises a housing 1 in which a pump plunger 2 is 
reciprocally mounted. Forming an extension of and threaded to the lower 
end of the housing 1 is a nut 3 within which is supported a bushing 4, 
forming the pump cylinder for the plunger 2. An annular space or fuel 
chamber 5 surrounding the bushing 4 within the nut 3 is supplied with fuel 
at a relatively low supply pressure via the passage means 6 in the housing 
1 from an external fuel inlet connection 7 in a well-known manner, the 
fuel chamber 5 also being in communication with an outlet connection (not 
shown) also in a well-known manner. The plunger 2 has the usual central 
passage (not shown) at the lower end thereof and the usual external 
metering groove helix 8 adjacent to its lower end by which opening and 
closing of the lower port 9 and upper port 10 in the bushing are 
controlled during each downward stroke of the plunger 2 to deliver a 
predetermined volume of fuel through the lower open end 11 of the bushing 
for injection into the cylinder of an engine (not shown) via the fuel 
injector or fuel injector nozzle of the invention, to be described, at the 
bottom of this unit. Other details of the upper or pump part of the unit 
are not important to the present invention, and are common to conventional 
constructions of the type, for example, as shown and described in such 
prior patents as U.S. Pat. No. 2,951,643 entitled "Fuel Injector with 
Pilot Injection" issued Sept. 6, 1960 to Royce G. Engle, Jr. and U.S. Pat. 
No. 2,898,051 entitled "Fluid Injection Device" issued Aug. 4, 1959 to 
Conrad A. Teichert, and hence will not require further description herein. 
The nut 3 has an opening 3a at its lower end through which extends the 
lower end of a fuel injector or fuel injection nozzle, hereinafter 
referred to as a nozzle, in accordance with the invention. The nozzle 
includes a nozzle body, which for ease in manufacturing and assembly is 
formed in two parts and includes a spring retainer or cage 12 with a 
spring chamber 14 therein and a nozzle valve body 15, the lower end 15a 
thereof extending through the opening 3a and having a piston or plunger 
valve, generally designated 16, reciprocally mounted therein in a manner 
to be described. As shown, the nozzle valve body 15 is enlarged above its 
lower end 15a to provide a shoulder 15b which seats on a shoulder 3b 
provided by the through counterbore in the nut 3 and the upper enlarged 
end of the nozzle valve body abuts against the spring cage 12 which, in 
turn, abuts against the lower end face 4a of the bushing 4. The threaded 
connection 17 of the nut 3 to housing 1 holds the nozzle valve body 15, 
spring cage 12 and bushing 4 clamped in stacked end-to-end relation 
between the shoulder 3b of nut 3 and the bottom face 1a of the housing 1. 
The spring cage 12 has a predetermined radial clearance between its outer 
peripheral surface and the adjacent inner peripheral surface of the nut 3, 
whereby the spring chamber 14 can be vented in a manner and for a purpose 
to be described. 
The nozzle valve body 15 is provided with a stepped bore therethrough 
providing, in sequence, an internal annular wall 20 extending a short 
distance from the upper end of the valve body, an internal wall 21, with 
an intervening radial shoulder 22 therebetween, and an internal annular 
sleeve or wall 23 which is open to the engine combustion chamber of a 
cylinder (not shown), the internal diameter of wall 23 being greater than 
the internal diameter of wall 21 but less than the internal diameter of 
wall 20 in the construction illustrated. 
The plunger valve, which is reciprocably mounted within the nozzle body, in 
the construction illustrated, is fabricated in two pieces that are 
suitably secured together as by an inertia or electron beam weld into a 
unitary structure and, in the preferred embodiment, includes a lower stem 
portion 30 which has a close sliding lapped fit with the bore portion of 
the valve body forming the internal annular wall 23, an intermediate stem 
portion 31 of a diameter to be slidably received by the wall 21 and a 
stepped reduced diameter upper stem portion 32 terminating at an enlarged 
head 33, the stem portion 32 and head 33 extending loosely into the spring 
chamber 14 of cage 12. Between the shoulder 22 at the upper end of the 
valve body 15 and the annular retainer ring 34 encircling the stem portion 
32 in abutment against the underside of head 33 is a compression spring 35 
which serves to urge the plunger valve 16 upward within the valve body to 
a retracted position, the position shown in FIGS. 1 and 2, at which the 
head 33 of the plunger valve abuts against a stop wall 36 defining the 
upper wall of the spring chamber 14 within the cage 12. 
Extending longitudinally within the lower stem portions 30 and 31 of the 
plunger valve 16 is an internal fuel passage 41, the upper and lower ends 
of which are closed. As shown, the upper end of the fuel passage 41 is 
closed, beneath this closed end, the walls of the stem portion 31 defining 
this portion of the passage 41 are provided with one or more transverse 
inlet passages 42 whose outer ends terminate at an annular groove 43 
formed on the outer periphery of the stem 31, next adjacent to the upper 
end of stem 30, whereby the passage 41 can be placed in communication with 
fuel at high injection pressure in a manner to be described. As shown, the 
lower end of the fuel passage 41 is also closed and above its closed end, 
the walls of the stem 30 portion defining this passage are provided, if 
desired, with one or more radial extending pilot spray orifices 44, only 
one being shown, and above the pilot spray orifice 44, if used, this wall 
is provided with a plurality of radial extending spray orifices 45, fuel 
being discharged through these orifices which serve as discharge outlets 
during the injection period, to be described, but discharge from these 
orifices is normally prevented by the closure thereof by the wall 23 of 
the valve body 15 when the plunger valve 16 is in its retracted position, 
as shown. 
The lower end face 4a of the bushing 4 also serves as a closure seat for a 
circular check valve or disk 50. The check valve or disk 50 is disposed in 
a cavity 51 formed in the upper end of the cage 12, the size of this 
cavity extending laterally beyond the lateral extremities of the open end 
11 of the pump cylinder in bushing 4 and serves to loosely guide the check 
valve or disk 50. A central protruberance 52 is provided at the bottom of 
the cavity 51 and serves to limit opening travel of the check valve or 
disk 50. 
The cavity 51 also forms the upper end of a fuel passage means connecting 
the open end 11 of the pump cylinder with the fuel discharge outlets or 
spray orifices 44 and 45, this passage means including longitudinally 
extending passages 53 in the cage 12 that are connected at one of their 
ends with the cavity 51 and at their opposite ends with a connecting 
annular groove 54 provided in the lower end face of a cage 12, in the 
construction shown. This annular groove 54, in turn, is in communication 
with one end of connecting passages 55 in the upper end of the valve body 
15, the opposite ends of these connecting passages 55 intersecting the 
stepped bore in the valve body 15 by extending through its wall 23 next 
adjacent to the wall 21 to place these passages in fluid communication 
with the annular groove 43 in the plunger valve 16. 
From the above description of the passage means used to connect the 
discharge or spray orifices 44 and 45 of the plunger valve 16 to a source 
of high pressure fuel, such as the pump cylinder of the injector pump, it 
will be apparent that the large volume of the spring chamber 14 in the 
cage 12 is not in the high fuel pressure circuit of the injector thereby 
permitting better control of fuel injection. Any internal leakage of 
pressurized fuel to the spring chamber 14 is drained therefrom by means of 
a radial passage 60 extending from this spring chamber through the walls 
of the spring cage 12 to an annular groove 61 on the outer periphery of 
the cage 12, fuel then flowing from this annular groove through the 
previously described clearance space between the cage 12 and the nut 3 to 
the annular space or fuel chamber 5, as previously described, containing 
fuel at a relatively low supply pressure. 
In operation, beginning with the parts in their positions as shown in FIGS. 
1 and 2 of the drawings, with the plunger 2 at the top of its stroke, fuel 
introduced through the inlet connection 7 enters the fuel chamber 5 and 
flows through the ports 9 and 10 into the pump cylinder below the plunger 
2. As the plunger 2 starts down, fuel is displaced back into the supply 
chamber 5 through the lower port 9 and up through the central passage (not 
shown) in plunger 2 and through the upper port 10. When the lower port 9 
has been covered by the plunger 2, bypass continues through the upper port 
10 until it is covered by the plunger upper helix of helix groove 8 at 
which point the fuel in the pump cylinder of the bushing 4 is compressed 
to unseat the check valve 50. When this pressure reaches the pre-selected 
atomizing pressure determined by the spring 35 biased against the 
differential area of bore 21 and 23, the variable area orifice feature of 
the nozzle will start fuel atomization first in the pilot spray orifice if 
it is used and then in the main orifices 44. The degree to which the main 
orifices open will be a function of engine speed and quantity of fuel 
injected, as determined by position of helix 8 with relation to port 10. 
As shown schematically by the broken lines in FIG. 2, the spray development 
from each spray orifice starts with a nearly vertical component V that 
sweeps up to a substantially horizontal component H from the start of 
uncovering of a spray orifice to the final full uncovering of the spray 
orifice as it moves beyond the lower edge of inner peripheral wall 23 of 
the nozzle body 15. However, it should be realized that this full sweep, 
just described, will not occur under all operating conditions. For 
instance, at 50% fuel input, the spray angle would not reach the 
horizontal position. It would, however, always start at the nearly 
vertical position. As the fuel pressure is dissipated during fuel 
injection, the spring 35 will again act to retract the plunger valve to 
the retracted position shown in the drawings, the spray orifices 45 and 44 
being sequentially closed off in that order by the inner wall 23 during 
retraction of the plunger valve 16 therein. 
Movement of the plunger valve from the retracted position to the extended 
position is effected by the high injection pressure of the fuel acting on 
the differential area of the plunger valve, which is an area corresponding 
to the difference in area of 23 and 21. The spring 35, of course, biases 
against the fuel pressure acting on the differential area. Accordingly, 
the load of spring 35 to control a selected, predetermined fuel injection 
pressure can be much lower than that used in conventional fuel injectors. 
In addition, it should also be realized that the plunger valve 16 will 
also be acted upon by the pressure in the cylinder (not shown) to assist 
it in moving from the extended position to its retracted position. 
In the event the plunger valve 16 fails to retract from its extended 
position to its retracted position for any reason at the end of the 
injection cycle, a reverse flow of fuel and combustion gases from the 
cylinder of the engine via the spray orifices and the passages in the 
plunger valve 16 and the passage means in the valve body 15 and cage 12 to 
the cavity 51 and then into the pump cylinder is prevented by closing of 
the check valve or disk 50 against its seat 4a on the bushing 4. 
As previously described, the lower stem portion 30 of the plunger valve 16 
is in a lapped fit relative to the internal wall 23 of the nozzle body 15 
to thereby suitably minimize the possibility of fluid flow in the 
clearance space between these elements in one direction and to prevent the 
flow of gases from the engine cylinder in the opposite direction. In order 
to provide a further seal between these elements, the lower end of the 
stem 30 of the plunger valve 15 is provided with a series of shallow 
annular seal grooves 62 adjacent to its free end, which grooves, during 
the operation of the subject fuel injector, will fill with carbon from the 
combustion products in the engine cylinder to thereby form a carbon seal 
in each of the grooves which will be in sliding sealing engagement with 
the lapped surface of wall 23 of the valve body 15. 
By reason of the spray orifices 44 and 45 being closed off by the sleeve 
wall 23 of the nozzle body, except when sufficient fuel pressure exists to 
force the plunger valve to its extended position, the start and finish of 
the injection period for the subject fuel injector is much more "sharp" 
than is the case with previous constructions. Because of the way the spray 
pattern is developed, as previously described, during the opening movement 
of the plunger valve to effect injection, the hole sizes and shapes of 
these spray orifices are less critical than in conventional structure and, 
regardless of the size or shape of these spray orifices, no fuel is 
available for afterflow or drip at the end of an injection period since 
these spray orifices are fully retracted within and closed off by the 
sleeve wall 23 of the nozzle body when the plunger valve is in its 
retracted position. Also, as will be evident and as previously described, 
the positive closing of these spray orifices 44 and 45 after each 
injection period resulting from the withdrawal of the plunger valve stem 
30 and its close fit in the sleeve wall 23 effectively eliminates any 
possibility of air or combustion gases being blown into the fuel passage 
41 from the combustion chamber of the engine cylinder, not shown, with 
which this fuel injector is associated. 
It will be apparent that in the subject fuel injector, as just described, 
it has only a back flow valve, in the form of check valve 50, ahead of the 
spray orifices, and that the variable area orifices formed by spray tip 
holes in the plunger valve 16 and the lower end of the nozzle valve body 
15 serves the same function as a conventional needle valve, but with these 
important differences, as follows: 
There is no throttling of fuel flow at the start and end of injection; 
there is no raw fuel remaining in a "sec" as there is none; the spray 
orifices are retracted into the nozzle valve body so that they are not 
exposed to the hot combustion gases in the cylinder with which the 
injector is associated; and, that all of the fuel injected during each 
fuel injection cycle is injected at essentially the same pressure, thus 
insuring proper atomization for all of the fuel injected during a cycle. 
In the alternate embodiment of the fuel injector shown in FIG. 3, wherein 
like parts are identified by the use of the same reference characters as 
used in the description of the embodiment shown in FIGS. 1 and 2, the 
plunger valve 16 in this embodiment has the lower end of its lower stem 
portion 30 formed integral with an enlarged valve head 65 to provide an 
annular flange 66 extending radially outward adjacent to the outer 
periphery of the lower stem portion 30, which flange abuts against the 
free end face at the lower end 15a of the nozzle body thereby serving as a 
stop to limit retraction of the plunger valve into the nozzle body 15, in 
lieu of having the head 33 of the plunger valve abutting against the wall 
36, as described with reference to the embodiment of the plunger valve 
shown in FIGS. 1 and 2. Of course, in this embodiment, the axial extend of 
the upper stepped stem portion 32 of the plunger valve would be less than 
that shown in the embodiment of this plunger valve illustrated in FIGS. 1 
and 2 so that the valve head 65 would act as the retraction stop in the 
manner previously described, instead of having the head 33 abutting 
against the stop wall 36. In this alternate embodiment, the valve head 65 
would then act as a secondary valve preventing cylinder gases from 
entering the injector and it would also serve to protect the orifice 
control end of the sleeve wall 23 from the hot gases of combustion within 
the cylinder, not shown, with which this fuel injector is associated. 
Although the plunger valve 16, in both embodiments illustrated, is provided 
with at least one pilot spray orifice 44, it should be realized that, if 
desired, these pilot spray orifices need only be used in an application 
where pilot injection is desired, and need not be used in those engine 
applications where pilot injection is not required. However, if pilot 
spray orifices are used, the plunger valve rotational position and the 
direction of the pilot spray orifices 44 relative to the cylinder (not 
shown) would be targeted at the ignition source within the cylinder of a 
spark ignition-fuel injection type of engine. 
Although the fuel injector of the invention is shown and described as being 
part of a unit fuel pump-injector, it should be realized that the subject 
fuel injector can be used as a separate injector, for example, as a fuel 
injector nozzle in a pump and nozzle system for use with various types of 
engines. It will be apparent that when it is used in such a system, the 
fuel injector would be physically separated from the fuel pump but 
connected thereto by suitable conduits for the flow of fuel between the 
injector and the pump and that the fuel injector itself will then be 
supported within a suitable injector housing having a fuel inlet providing 
a structure corresponding to the open end 11 of bushing 4 and an outlet 
corresponding to the structure providing the fuel chamber 5 of the unit 
fuel pump-injector illustrated and, that this injector housing would also 
be constructed in such a manner so as to provide a suitable seat for the 
check valve 50 of the subject fuel injector. It should also be realized 
that the fuel injector shown could also be used as an atomizing nozzle for 
oil burners, gas turbines, Stirling engines or any liquid flow where a 
constant degree of atomization was desired even though flow varied.