Fuel management system for internal combustion engines

A fuel management system that separates the three-dimensional functions of fuel injection pressure, volume and timing and thus eliminates co-dimensional dependencies. The system of the invention utilizes volumetric injection control and is based on displacement of a predetermined volume rather than volume generated by flow due to pressure with respect to time, as in prior art systems. In one of its simplest configurations, the fuel management system combines a pair of "sister" injectors and a volumetric injection control assembly comprised of a simple displacement piston which free floats a given distance to deliver fuel alternately to each injector. When one injector's solenoid valve operates to activate it's main injection, it simultaneously loads the adjacent injector with a predetermined volume of fuel for the adjacent injector's main volume injection. Throttling fuel volume is controlled by controlling the length of the cylinder's barrel containing the free floating piston.

BACKGROUND OF THE INVENTION 
In recent years, governments have adopted emission standards for internal 
combustion engines which standards require lessening of harmful emissions 
from internal combustion engines. Initially, these standards were imposed 
upon gasoline fueled engines, and more recently standards are being 
adopted for diesel engines. Because of their durability and high power 
output, diesel engines are firmly established as the engine of choice in 
the trucking and off-the-road industries. There are over 150,000,000 
diesel engines currently in operation worldwide, with over 10,000,000 new 
engines entering the market each year. In anticipation of these new 
standards which require reduced emissions, diesel engine manufacturers are 
developing and modifying the existing fuel management systems. With the 
next generation of engines utilizing radical changes in design not 
anticipated to be available until at least the year 2000, the only 
practical approach to meeting fuel emission standards without the 
sacrifice of fuel economy will have to be improvements in the existing 
designs of fuel management systems. At the present time, changes to the 
fuel management systems designed to meet the emissions requirements will 
add considerably to the cost of the engines or reduce fuel efficiency, or 
both. This is primarily because efforts to reduce emissions have been 
directed toward adding on to, or modifying, existing fuel system designs 
by incorporating higher precision pressure components and faster timing 
control devices. These efforts are directed specifically to control only 
one of the several factors of emissions--fuel volume efficiency. 
However, when higher pressure is used to improve and control emissions, the 
precise pressure devices become very costly, and within some design 
configurations, become impractical and/or volume control efficiency is 
sacrificed. This is because known designs are co-dimensional in actual 
design concept and function. In other words, fuel pressure, timing and 
fuel volume are all interdependent and inter-related in the current 
designs. Moreover, there are practical limitations on engines with regard 
to pressure and timing when prior art fuel management systems are 
employed. Therefore, in part, attempts to modify and improve existing 
engine designs are restricted. This is because the over-all engine 
investment increases the need to improve the current fuel management 
systems. 
There is therefore a need for technological improvements that will meet 
emission control standards, without change to existing basic engine 
designs, or without sacrifice of fuel volume efficiency. 
All current designs of diesel engines utilize fuel-injection systems to 
meet the fuel metering requirements of the engine. These fuel injection 
systems include a variety of mechanical and electrical configurations 
designed to meter fuel to each cylinder in the most efficient manner. In 
most systems, mechanical components make up the greater cost, with 
electronic components being the least expensive to manufacture. 
The mechanical components of a fuel management system are divided into two 
main groups, the low pressure components and the high pressure components. 
The low pressure components consist generally of the fuel tank, fuel 
filter, fuel supply pump and/or lift pump. These low pressure components 
utilize standard precision parts, and in today's designs are generally 
acceptable from both a cost effectiveness and efficiency standpoint. At 
the current state of the art, even with modest increases in efficiency to 
the low pressure components, very little overall system efficiency is 
gained. 
The components that make up the high pressure group include the injection 
pump, injector supply rail, overflow valves, high speed solenoid valves 
and injectors. These high pressure components have high precision and high 
reliability by design. Thus, these components represent a substantial part 
of the manufacturing cost of a fuel management system. Unlike the low 
pressure components, a small increase in efficiency in any one of the high 
pressure components can gain a modest increase in overall fuel management 
system efficiency. 
Both the high pressure and low pressure components of the fuel system are 
integrated into the supply and return lines and are interfaced with the 
electrical monitoring devices through an electronic control module or 
"ECM". The function of the control module is to receive inputs from the 
engine and the operator and produce output commands to the controllable 
components of the fuel injection system. 
The speed, reliability and cost of the primary electrical components far 
exceed the speed, .reliability and cost of the secondary electronic 
components or any part of the mechanical components of a fuel management 
system. In general, primary electrical components of a fuel injection 
system for current diesel engine designs, like the electronic control 
module, are adequate. However, the secondary electrical components, such 
as the electronically controlled solenoids within the high pressure group, 
are currently being upgraded in order to meet the co-dimensional demands. 
These electronically controlled solenoids are an integral part of the fuel 
injectors and the need for faster acting and lower power solenoids are 
necessary to improve performance and lower emissions. 
Because of the co-dimensional dependencies of fuel pressure, volume and 
timing in current fuel management systems, most of the efforts to meet 
emission standards have been directed to both the mechanical and 
electrical components in the high pressure group. In recent years most of 
the improvements involved the co-dimensional relationship between timing 
and pressure, higher precision manufactured components, and faster acting 
solenoid valves, all of which resulted in small advancements in the fuel 
management systems for the diesel industry. 
As an example of prior art improvements in fuel management systems, some 
such systems use a cam lobe, integral with the existing mechanical valve 
cam located on top of the engine. This cam lobe activates a plunger in the 
injector for producing the necessary pressure of injection. The injection 
pressure in such systems is controlled by the profile and the velocity of 
the cam lobe that drives a plunger downwardly through a cylinder inside 
the injector. The cam lobe forces the injector's plunger to travel the 
full injector stroke, thereby dispensing the full volume of the injector's 
cylinder during each injector cycle, with fuel constantly being internally 
bled off to the fuel tank through the solenoid valve. The precise timing 
of the injection is initiated by energizing the solenoid valve, thereby 
directing the fuel towards the injection nozzle instead of the tank, with 
fuel metering being produced by precisely timing the moment the solenoid 
is de-energized. 
In these prior art systems, injection pressure is thus controlled by the 
leverage and speed of the cam profile at the time of injection and the 
internal size of the injector nozzle, while the volume of fuel injected is 
controlled by varying the "on-time" of the solenoid valve. As is true with 
other prior art systems, this system is co-dimensional, and thus the 
timing of the solenoid verses the cam profile and engine speed has to be 
precise to control the fuel metering. 
Changing the timing of the injection also changes the point on the cam 
where injection occurs, and a given solenoid valve's "on-time" will result 
in a different amount of fuel delivered. This requires that different 
control values be programmed into the control module to compensate for 
timing, resulting in an "averaging" of the fuel metering. Moreover, when 
cam velocity changes, the rate of fuel forced through the injector nozzle 
changes, which also changes pressure in the nozzle, and thus injection 
pressure also becomes co-dimensional with timing and engine speed. Fuel 
volume efficiency is sacrificed due to injection variations caused by 
imperfect repeatability of the cam lobe, the control solenoids, and the 
control modules compensating for timing. 
Other prior art systems use a high pressure common rail with a high 
pressure piston-rotary cam style pump that feeds high pressure fuel to the 
common fuel rail for storage prior to the injection event. Each fuel 
injector is connected to the common rail through a solenoid which, in 
conjunction with the control module, controls the injection timing and 
fuel volume. 
Internally, the injector has a needle spool valve that is under high 
pressure on one end, and is activated when the opening of the solenoid 
valve creates an imbalance in pressure at the top of the needle, thus 
lifting the needle and allowing high pressure to flow through the nozzle 
chamber and into the engine. 
The volume of fuel injected with this system depends on the stored high 
pressure and precise timing, and thus this system is co-dimensional. When 
higher pressure is required in order to reduce emissions, high pressure 
waves (Helmoltz resonance) occur throughout the high pressure components 
causing fuel metering problems, and precision fuel delivery is thus 
sacrificed in order to control emissions. Additional components and fuel 
metering "averaging" is added to the fuel management system to compensate 
for these high pressure waves. Moreover, high pressures and the high 
pressure waves subject the parts of the fuel system to design and 
durability problems. 
During normal operation of a fuel injected engine, the same volume of fuel 
is not injected into all cylinders due to imbalances in the system and the 
co-dimensional dependencies that exist. This condition is evidenced at 
slow idle by a roughness in engine speed. At higher throttle settings this 
imbalance in delivery is evident as a loss of fuel efficiency. "Averaging" 
is the fuel system designers way of estimating composite fuel delivery to 
the entire engine. Injection timing and other parameters are therefore 
based on the average fuel delivered to each cylinder rather than the 
actual delivery rate on a cylinder to cylinder basis. Using this 
"averaging" principle, there is a known popular style of injection system 
which features a mechanical or electronic governor actuator pump that has 
an integral timing device dedicated to each of the pump's plungers which 
are mated to a specific injector. The pump generates the necessary 
pressure and distributes the fuel to the individual injectors, while a 
mechanical control collar or electric solenoid controls the quantity of 
the fuel that is injected. The metered fuel is "averaged" by means of the 
pump's governor mechanism, either mechanically or electrically. Fuel 
timing and injection pressure are controlled by the same piston's volume 
chamber, and prior to injection the rotation of the pump is matched with 
the rotation of the engine. Therefore, this system is also co-dimensional. 
In all of these mechanical control systems of the prior art, many 
components must be manufactured to precise tolerances, while in the 
electrical/mechanical systems, fuel "averaging" is used to control actual 
metered fuel. Fuel volume efficiency is sacrificed due to timing 
variations of the electrically controlled governor. 
Another prior art system utilizes a "medium" pressure fuel rail which 
pressure is then intensified in the injector. The solenoid for each 
injector is activated to enable medium pressure fuel to flow from the 
supply rail to the top of an intensifier piston in the injector. With an 
area difference between the top and the bottom of the intensified piston, 
pressure is increased and medium pressure fuel is intensified into high 
pressure fuel. This high pressure intensified fuel then flows through a 
check valve into a nozzle chamber and into the engine. Fuel metering is 
controlled by varying the "on time" of a solenoid that passes fuel into 
the top or medium pressure side of the intensifier piston. By using 
intensified injection, very few components are under high pressure. 
However, the system is, like all prior art systems, co-dimensional. 
With all of the foregoing described prior art systems, the industry trend, 
in summary, is towards higher injection pressure of the fuel into the 
engine's piston chamber in order to meet future emissions standards. The 
problem with increasing the injection pressure, is that with a 
co-dimensional injection system, volume efficiency is sacrifice. 
The primary emphasis of the industry is to improve, by redesign and 
increased cost, the components that depend directly on pressure and timing 
to control volume. Fuel "averaging" is the trend established by the 
industry to overcome most of the co-dimensional dependencies. This in 
itself is netting less then the desired fuel volume efficiency. 
Moreover, additional fuel saving techniques like pilot injection, injection 
rate shaping, and inlet swirl become a secondary emphasis for fuel 
management systems. 
There is therefore a need for a fuel management system that can utilize the 
best available components of current designs, while having the flexibility 
of adding fuel saving features that are currently known to improve 
emission standards without "averaging" and sacrificing fuel volume 
efficiency. 
SUMMARY OF THE INVENTION 
When used in the description of the invention, the following terms have the 
indicated meaning: 
"Low fuel pressure" is the fuel pressure produced by the fuel tank pump 
that is applied to the input of the variable pressure main injection pump. 
This fuel pressure usually is in the 50-120 psi range and is used simply 
to move fuel from the tank to the high pressure pump. 
"Medium fuel pressure" is the fuel pressure produced by the variable 
pressure main injection pump. This fuel pressure constitutes the force 
that ultimately produces the pressure of injection and varies generally 
within the range of 1500-3500 psi in a developed system. This medium fuel 
pressure is applied to the lower pressure or larger surface area side of 
an intensifier piston that is integral to an injector body. 
"High fuel pressure" is the fuel pressure that is present at the injector 
nozzle and is directly proportional to the fuel pressure at the top of the 
intensifier. This high fuel pressure varies depending on atomization 
requirements for desired engine operating parameters will normally vary in 
the range of 12,000-27,000 psi. 
"VIC" is an acronym for "Volumetric Injection Control" assembly and refers 
to the invention's free floating piston assembly that is common to all 
configurations and applications of the invention. The "VIC" can be a 
separate assembly or can be integral with an injector or variable pressure 
pump. The "VIC" assembly can also have a separate pilot injection, free 
floating piston co-located as part of the assembly. However, this pilot 
"VIC" can also be located in a different assembly. 
"UNIVIC" is an acronym for a "Universal Volumetric Injection Control" 
assembly and refers to a "VIC" assembly that incorporates it's own valving 
and is configured to work with a multiple of two cylinders as in a "V" 
type of diesel engine. As is true with the basic "VIC" assembly, the 
"UNIVIC" assembly may have a separate pilot injection piston co-located in 
the same assembly or it may be mounted separately or integrally as a part 
of a variable pressure pump or intake manifold, cylinder head, etc. 
In the invention, a fuel management system incorporating the principles of 
the invention separates the three-dimensional functions of fuel injection 
pressure, volume and timing and thus eliminates co-dimensional 
dependencies. The system of the invention utilizes volumetric injection 
control and is based on displacement of a predetermined volume rather than 
volume generated by flow due to pressure with respect to time, as in prior 
art systems. 
The system of the invention in one of its simplest configurations combines 
a pair of "sister" injectors and a "VIC" assembly comprised of a simple 
displacement piston which free floats a given distance to deliver fuel 
alternately to each injector. In general, when one injector's solenoid 
valve operates to activate it's main injection, it simultaneously loads 
the adjacent injector with a predetermined volume of fuel for the adjacent 
injector's main volume injection. Throttling fuel volume is controlled by 
controlling the length of the cylinder's barrel containing the free 
floating piston. 
Since the system is based upon a displacement concept for volume control, 
the piston does not have to be maintained at constant pressure or travel 
at a precise time for exact volume control. This separates the three 
dimensions of pressure, volume and timing into independent controllable 
functions of the fuel management system. 
In another configuration of the invention, one "UNIVIC" assembly is used to 
meter fuel to, for example, alternating sets of injector fuel chambers 
while the injector control solenoid valve of the "next to be filled" 
injector is activated to accept fuel directed to it's chamber.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION 
FIGS. 1, 2 and 3 illustrate the preferred embodiment in which a single 
"VIC" assembly 33 is shared with and operates two intensified injectors 1A 
and 2A. FIG. 1 is the primary diagram for explaining the principles of 
operation of the invention since it shows the schematic of an intensified 
injector 1A combined with an intensified injector 2A and a "VIC" assembly 
33 all of which form a complete "VIC" injector unit A, B or C (see FIGS. 4 
and 5). In FIG. 1, items such as a fuel tank, lift pump, fuel filter, 
electronic controller, common fuel rail, etc. are omitted for ease of 
explanation, but these standard components of a fuel system are 
illustrated in FIG. 4. 
Referring now to FIGS. 1, 2 and 3, each of the injectors 1A and 2A has an 
intensifier assembly indicated generally by the reference numerals 48 and 
49, respectively, and a nozzle 54 or 55. The intensifier assemblies 48 and 
49 include intensifier pistons 9 and 10, respectively, which have upper 
portions 9a and 10a moveable in upper chambers 12a and 11a and lower 
portions 9b and 10b moveable in lower chambers 12b and 11b. The top 
surface areas of the upper portions 9a and 10a are substantially greater 
than the bottom surface areas of the lower portions 9b and 10b. 
Also included as a part of a "VIC" assembly 33 are check valves 15, 16, 17 
and 18. Check valve 15 is in line 31 leading from the upper chamber 12a of 
intensifier assembly 48 to the main VIC injector unit 46, while check 
valve 18 controls the direction of flow through line 56 from the lower 
chamber 12b to the main VIC injector unit 46. Check valve 17 is similar to 
valve 15 in that it controls the direction of flow in line 32 connecting 
the main VIC injector unit 46 with the upper chamber 11a of intensifier 
assembly 49, while valve 16 is in the line 57 from the main VIC injector 
unit 46 to the lower chamber 11b. 
The "VIC" assembly 33 provides both the main VIC injection unit 46 and VIC 
pilot injection unit 47 for each pair of cylinders of the engine. As is 
best seen in FIGS. 2 and 3, the body section 58 of the VIC assembly 33 
contains the main moveable barrel 36, which is moveable relative to the 
body section 58 against the resistance of spring 45, and the fixed main 
barrel 43. Barrels 36 and 43 form a part of the main VIC injection unit 46 
and have a longitudinal chamber 8 in which a free-floating piston 7 moves 
from end to end relative to the barrels 36 and 43. Body section 58 also 
contains the pilot moveable barrel 38, which is moveable relative to the 
body section 58 against the resistance of spring 44, and the fixed pilot 
barrel 42. Barrels 38 and 42 form a part of the pilot VIC injection unit 
47. Similar to the main VIC injection unit 46, moveable pilot barrel 38 
and fixed pilot barrel 42 have a chamber 5 in which a piston 6 is free to 
float from end to end relative to the barrels 38 and 42. The moveable main 
barrel 36 and the moveable pilot barrel 38 are coupled by plunger pins 41 
and 40 to an adapter 34 which is connected to a throttle linkage rod 35 
interconnecting the adjacent "VIC" assemblies, movement of the rod 35 
being controlled by a throttle servo control motor 30 (FIG. 4). Adjustment 
screws 39 in the adapter 34 provide for adjustment of the position of the 
moveable barrels 36 and 38 relative to the fixed barrels 43 and 42 and 
relative to the interconnecting adjacent VIC assembly 33. 
The described components of the "VIC" assembly 33 provide for control of 
the throttle or total fuel volume that flows into the chambers 8 and 5 of 
the main injector unit 46 and pilot injector unit 47, respectively. Since 
the moveable pilot barrel 38 is part of the same assembly as the moveable 
main barrel 36 and because they are connected together by adaptor 34, the 
pilot injection volume in chamber 5 is always a controlled ratio relative 
to the main injection volume in chamber 8. It should be understood, 
however, that the "VIC" assembly 33 can be designed so that the ratio of 
pilot to main inject volume changes with throttle position. 
FIGS. 2 and 3 show the mechanical and physical construction of an entire 
"VIC" injector unit that is shown schematically in FIG. 1. 
FIG. 4 shows a fuel management system representing the application of the 
invention in a six cylinder in-line diesel engine. In the system of FIG. 
4, three complete "VIC" injector units A, B and C, each of the type 
represented in FIGS. 1, 2, and 3 are shown together with a fuel tank 22 
from which fuel is pumped by a variable pressure pump 25 through the fuel 
supply line 23 which contains a fuel filter 24. Fuel discharged from pump 
25 flows through the main fuel supply line 13 to the three "VIC" 
assemblies 33, there being one "VIC" assembly 33 for each pair of engine 
cylinders. An engine speed and valve cam angle sensor 28 and an injection 
pressure sensor 29 in fuel supply line 13 continuously deliver their 
values to an electronic control module (ECM) 26. ECM 26 also receives 
additional information from sensors 20, which provide engine and exhaust 
temperatures, ambient air temperature and pressure, etc. In addition, the 
accelerator pedal 27 communicates the vehicle operator selected speed to 
the ECM 26 through wiring harness 53. The control module 26 acts on this 
information to appropriately control the pressure of the fuel pump 25, 
control the throttle servo control motor 30, and the timing of all 
solenoid valve coils associated with the solenoid valves of each "VIC" 
injector unit. 
For the purpose of explaining the operation of the invention, all the 
electrically controlled solenoids in FIG. 1 are either "latched open" for 
the passing of fuel or "latched closed" for the blocking of fuel. For 
example, in the schematic of FIG. 1, solenoid valve 1 and solenoid valve 2 
that form a part of injectors 1A and 2A, respectively, are always in 
opposite operating positions prior to a pilot or main injection 
occurrence. Thus, when one solenoid valve is open to the fuel supply line 
13, the adjacent "sister" solenoid valve is open to fuel vent line 14. As 
shown in the timing diagram of FIG. 5, activation of solenoid valve 1 and 
solenoid valve 2 do not have to occur simultaneously for proper operation. 
Similarly, solenoid valve 4 in the fuel vent line 14 and solenoid valve 3 
in fuel line 37 connecting the chamber 5 of the pilot VIC injection unit 
46 with intensifier 48 are also always in opposite operating positions in 
the schematic of FIG. 1, and depending upon activation of pilot injection, 
operate in conjunction with solenoid valve 1 and solenoid valve 2. Again, 
as shown in FIG. 5, timing between solenoid valve 3 and solenoid valve 4 
does not have to be exact although the sequence is always the same for 
proper operation. This flexibility in application illustrates that two 
solenoids can either be activated by the same coil or by the same control 
wire from the control module. 
Referring now to the diagram of FIG. 5, there is shown a crank angle timing 
diagram for a 6-cylinder, 4-stroke diesel engine in which three "VIC" 
injector units A, B and C have been installed. The injection sequence for 
"VIC" injector A will be described with reference to FIG. 5. Pilot 
injection of injector 2A is the first event in the sequence of operations 
to occur. Pilot injection of injector 2A requires that solenoid valve 4 
block fuel flow prior to fuel passing through solenoid valve 3, and that 
medium pressure fuel be present in fuel line 37 when medium pressure is 
applied through solenoid valve 1 and into intensifier piston chamber 12. 
To start pilot injection on injector 2A, solenoid valve 4 must close prior 
to the time of pilot injection so as to block fuel flow to the fuel vent 
line 14. At the time for pilot injection, solenoid 3 opens, allowing 
medium pressure fuel to force the pilot injection piston 6 toward injector 
2A forcing the fuel in chamber 5 and thereby pushing intensifier piston 10 
down a distance that the total volume in chamber 5 will allow, creating a 
metered pilot injection. 
Moreover, since the main injection piston 7 still has the medium pressure 
present in chamber 8, the main injection piston 7 will not move when pilot 
injection occurs in injector 2A. 
Due to the area difference between the top and bottom of the intensifier 
piston 10, high pressure pilot injection will develop and move through 
injector nozzle fuel line 50. This high pressure fuel will lift the nozzle 
lift check valve 52 and enter the engine's cylinder chamber, thus 
completing the pilot injection. 
For the main injection of injector 2A, solenoid valve 2 latches closed, as 
seen in FIG. 1 and FIG. 5 and the top of piston 10 is exposed to the 
medium pressure supply causing main injection on injector 2A. The balance 
of the fuel remaining in chamber 11b after pilot injection is then forced 
out through injector nozzle line 50 at high pressure and out through the 
nozzle lift check valve 52 for injection into the engine's cylinder 
chamber. 
Again, since the pilot injection piston 6 still has the medium pressure 
present through solenoid 3, the pilot injection piston 6 will not move 
when main injection occurs on injector 2A. Similarly, since the main 
injection piston 7 still has the medium pressure present through solenoid 
1, the main injection piston 7 will not move when main injection occurs on 
injector 2A. 
Since medium fuel pressure from supply line 13 is present in chamber 12a at 
the top of intensifier piston 9, this same pressure will force fuel 
through check valve 15 in line 31 leading to the main VIC injector unit 46 
and force the main volume piston 7 to the position shown (to the right in 
FIG. 1). When the fuel volume of the chamber 8 of the main VIC injector 
unit 46 is dispensed by piston 7 moving to the right (FIG. 1), the fuel 
will enter only chamber 11b of the intensifier assembly 49 due to the 
resistance of the nozzle lift check valve 52 and the allowance of the 
internal venting line 51, and with solenoid valve 4 latched open, fuel 
will be vented from the top of piston 10a. With solenoid valve 3 latched 
closed, the pilot injection piston 6 will not dispense the fuel in the 
chamber 5 of the pilot VIC injection unit 47. However, because the volume 
in chamber 8 of the main VIC injection unit 46 is equal to the volume that 
was present on the other side of the piston 7 prior to the occurrence of 
main injection from injector 1A, a volume of fuel equal to the volume of 
chamber 8 is forced through check valve 16 in fuel line 57 leading to the 
intensifier assembly 49 of injector unit 2A. This precise volume of fuel 
flows into chamber 11b of the intensifier unit 49 below intensifier piston 
10. As chamber 11b fills with fuel, intensifier piston 10 moves upward 
venting the fuel in chamber 11 above intensifier piston 10 through 
solenoid valve 2 and solenoid valve 4 to the fuel vent line 14 which 
returns it to the fuel tank 22 (see FIG. 4). 
It should be noted that the intensifier piston 10 will travel upward only 
the distance required to receive the measured volume from the main VIC 
injector unit 46 when piston 7 moves to the right. 
Just after the main injection on injector 2A, and prior to the main volume 
fill of injector 1A, solenoid valve 3 and solenoid valve 4 will be 
returned to their pre-pilot starting position, as illustrated in the 
timing diagram, FIG. 5. 
The medium pressure fuel is supplied to injector 1A from the common fuel 
supply line 13. The solenoid valve 1 of injector 1A is shown in FIG. 1 in 
the state that permits flow from the fuel supply line 13 into the chamber 
12a of the intensifier assembly 48 above the intensifier piston 9. 
Therefore, the intensifier piston 9 will be in the down position just 
after fuel supplied from the main VIC injector unit 46 is discharged from 
the nozzle 54 of injector 1A. 
Just after the main injection on injector 2A, and the reset of solenoid 
valve 3 and solenoid valve 4, solenoid valve 1 latches closed to allow 
relief flow to the fuel vent line 14, allowing the main injection piston 7 
to move toward injector 1A thus forcing the volume of fuel in chamber 8 
through check valve 18 into the chamber 12b beneath piston 9 in injector 
1A. Continuing through the timing sequence, with injector 1A now loaded 
with the metered amount of fuel, and the pilot injection piston 6 awaiting 
the latching open again of solenoid valve 3 to pilot inject injector 1A, 
injector 1A is now ready for it's control command to activate both the 
pilot and main injection as illustrated in FIG. 5. 
To start pilot injection on injector 1A, solenoid valve 4 must close prior 
to the time of pilot injection so as to block fuel flow to the fuel vent 
line 14. At the time for pilot injection, solenoid 3 opens, allowing 
medium pressure fuel to force the pilot injection piston 6 toward injector 
1A forcing the fuel in chamber 5 and thereby pushing intensifier piston 9 
down a distance that the total volume in chamber 5 will allow, creating a 
metered pilot injection. Moreover, since the main injection piston 7 still 
has the medium pressure present in chamber 8, the main injection piston 7 
will not move when pilot injection occurs in injector 1A. 
Due to the area difference between the top and bottom of the intensifier 
piston 9, high pressure pilot injection will develop and move through 
injector nozzle fuel line 50 of injector 1A. This high pressure fuel will 
lift the nozzle lift check valve 52 and enter the engine's cylinder 
chamber, thus completing the pilot injection. 
With solenoid valve 1 of injector 1A latched open and fuel flowing into the 
chamber 12a of the intensifier assembly 48 of the injector 1A, main 
injection of injector 1A will then occur. In the state illustrated in FIG. 
1, solenoid valve 2 of injector 2A is latched open which has vented the 
fuel from the top of piston 10 into the fuel vent line 14. Injector 2A 
will then be filled with the predetermined volume of fuel as controlled by 
main injector piston 7. 
This action of shuttling the fuel with prefill of an injector first, pilot 
injection second and then the main injection third, continues in a 
reciprocal manner alternately between the two injectors within each "VIC" 
injector unit on an engine as illustrated in the timing diagram, FIG. 5. 
For the purpose of describing the principles of operation, FIG. 1 is shown 
in the operational sequence that shows injector 1A injection complete, and 
the foregoing illustrates that at the same time main injection occurs from 
injector 1A, a precise amount of fuel is volumetrically metered into the 
opposing injector 2A. Upon the next set of commands, and according to the 
timing diagram of FIG. 5, injection, first pilot and then main, of fuel 
from injector 2A will occur. 
In any stage of operation, timing precision is dependent only on a solenoid 
entering a certain state and not on the amount of time the solenoid has to 
remain in that particular state. This flexibility in the design eliminates 
"field stabilization" considerations in the solenoid cores and armatures. 
It should also be noted that there are other possible methods of changing 
or controlling the total movement or travel of the moveable barrels 36 and 
38 and the main injection piston 6 and pilot injection piston 7. One other 
possible method is not to use a moveable barrel but instead fix the barrel 
or cylinder position and use a threaded screw inserted through the end of 
the barrel to limit the travel of the reciprocating piston. 
As previously indicated, most fuel injection systems for diesel engines are 
controlled by an electronic control module 26, or ECM. In FIG. 4 the 
sensors (not shown) for the engine, monitor ambient air temperature, 
barometric pressure, exhaust temperature, and the boost pressure of a 
turbo charger if used, the position of the accelerator pedal 27 and the 
engine speed sensor 28 and are linked directly to the electronic control 
module 26. 
An additional feature of the invention is that the control module 26 can 
control a throttle servo control motor 30 or mechanical linkage which 
controls the position of the moveable barrels 36 and 38 of the "VIC" 
assembly 33 through a control linkage 35, in a direct linear control thus 
assuring positive, accurate and balanced fuel delivery to all cylinders 
under all conditions. Moreover, with the system of the invention, once the 
control dimensions are isolated from each other, there are many 
possibilities of control through the control module 26 that can be readily 
utilized by persons skilled in the art. The fuel injection system of the 
invention achieves the accurate control of volume of the main injection, 
the accurate control of volume of the pilot injection, both independent of 
system pressure or timing, with the pilot injection and main injection 
operating independently of each other. 
The system also has the capability of increasing the main injection 
pressure, rate shaping of the injection pulse and optimal utilization of 
the control module while maintaining exact volume control for total system 
efficiency. The system of the invention can be applied to existing fuel 
injection management systems of various types at a reasonable cost. 
The basic unit of the invention is adaptable with any style injector 
although it is designed primarily to work with an intensified injection 
system, thus allowing the "VIC" components to operate in a medium pressure 
zone and take full advantage of low critical part tolerances of the fuel 
management system. Moreover, using intensified injection along with "VIC" 
components conserves total system energy between the medium pressure zone 
and the high pressure zone. 
Also, where applicable, the invention allows a single "VIC" assembly of the 
invention to control fuel volume to more than two cylinders, thus reducing 
cost on engines with large numbers of cylinders. Thus, although the 
invention has been illustrated in connection with an injection unit for 
each two injectors of a four, six or eight cylinder system, obviously, a 
single "VIC" injector unit containing both main and pilot injection 
assemblies can be utilized to control all cylinders for a V-8 engine when 
the reciprocal action is applied to opposing banks of four cylinders each. 
In such a configuration, the "VIC" control solenoids shuttle fuel from the 
main piston-barrel assembly while each injector solenoid activates "open", 
by timing, thus receiving the predetermined volume of fuel. Moreover, the 
pilot control solenoid shuttles fuel from the pilot piston-barrel assembly 
while each injector's solenoid, by timing, is activated for the 
pre-determine pilot injection. And again, by timing, each injector's 
solenoid is activated allowing intensified pressure to inject a 
pre-determined non-pressure dependent fuel volume into the engine's 
cylinder chamber. 
Using the principles of the invention, fuel volume, timing and pressure are 
totally independent functions as used in the "VIC" or "UNIVIC" 
configurations. Therefore, secondary features for diesel fuel management 
systems become not only feasible but practical as well. For example, the 
system of the invention makes precise control of pilot injection practical 
utilizing the same volumetric principle. With both the pilot and main 
injection using the piston-barrel concept, only the volume of fuel to be 
injected later enters the injector, resulting in total system conservation 
of energy. 
Having thus described the invention in connection with preferred 
embodiments thereof, it will be evident to those skilled in the art that 
various revisions and modifications can be made to the preferred 
embodiments described herein without departing from the spirit and scope 
of the invention. It is my intention however that all such revisions and 
modifications that are obvious to those skilled in the art will be 
included within the scope of the following claims.