An injection valve arrangement for a high-pressure injection of liquid fuel into a working chamber of an internal combustion engine with the arrangement including at least one valve needle which is urged by a spring force in a closing direction so that a pair of sealing cones associated with the valve needles are brought into engagement with a pair of separate valve seats. The valve needle is liftable in a direction opposite a flow direction effective in the injection process by hydraulic pressure of the fuel to be injected. Pressure chambers having a diameter larger than the respective valve seats are provided and communicate by way of appropriate ducts which merge to form a common flow cross-section. At least two separate line connectors are provided for receiving separate fuels and/or fuel components with the line connectors directing the fuels and/or fuel components to the respective pressure chambers.

The present invention relates to a valve arrangement and, more 
particularly, to an injection valve arrangement for high-pressure 
injection of a fuel into a working chamber of an internal combustion 
engine which arrangement includes two needle valves disposed, preferably, 
concentrically within one another, with the needle valves being urged by a 
spring force in a closing direction so that associated sealing cones or 
the like are each forced onto a separate valve seat, the needle valves 
being liftable from their valve seats in a direction opposite a flow 
direction effective in the injection process by hydraulic pressure in the 
fuel to be injected, and a pressure chamber, with a larger diameter than 
the corresponding valve seat and surrounding the needle valves, being 
provided for each needle valve in a flow direction upstream of the valve 
seat, with the two pressure chambers communicating, by way of appropriate 
ducts disposed inside the injection valve, with a line connection for fuel 
on the injection valve and merging to form a flow cross-section which is 
common for the two needle valves when the needle valves are lifted. 
A double-needle valve arrangement of the aforementioned type is proposed 
in, for example, German Pat. No. 1,284,687. In this proposed valve 
construction, pre-injection and main injection of diesel fuel into a 
working chamber of a diesel engine are achieved. 
The aim underlying the present invention resides in providing a 
double-needle valve arrangement of the aforementioned type by which it is 
possible to realize a multi-fuel mixed operation of an injection valve. 
According to advantageous features of the present invention, the injection 
valve is provided with two separate line connectors for fuel with each of 
the two pressure chambers being connected by way of separate ducts with 
only one of the line connectors. 
By virtue of the provision of a double arrangement of line connections to 
the injection valve and separate ducts to the pressure chambers in 
accordance with the present invention, two different fuels may be injected 
simultaneously by a single injection valve. For this purpose, a double 
injection pump is provided with the pump including two different rows of 
feed or injection pistons for each row of working chambers in the internal 
combustion engine with the rows of the pistons being independently 
controllable. 
During multi-fuel mixed operation, the volume ratio between one fuel 
component and the other must be variable as a function of the load of the 
engine. Consequently, an injection of a mixture of the two fuels through a 
normal injection valve is not possible. Often, the fuel components cannot 
be mixed with one another in a homogeneous fashion and with long-term 
stability due to the different physical characteristics and, after a 
relatively short period of time, the fuel components separate again. A 
prerequisite for successful use, for example, of certain fuel additives 
which are intended to improve combustion and hence the composition of the 
exhaust gases, is by way of an intimate mixture of the additives with the 
fuel. This is achieved in accordance with the present invention, by 
utilizing the injection valve in a common spray cross-section for the two 
fuel components as a result of the high turbulence. 
In accordance with additional advantageous features of the present 
invention, both valve seats are disposed in a valve housing and the two 
needle valves are adapted to open or close simultaneously. To insure an 
approximate simultaneous lifting of the valves, stops and shoulders or the 
like are provided for limiting the relative travel of one of the needle 
valves relative to the other to a small fraction of the absolute needle 
valve travel. The small relative travel need only be slightly larger than 
the largest possible manufacturing tolerances for the valve seats with 
respect to their axial spacing. 
According to the present invention, the two valve needles may be 
constructed as a single valve needle with two sealing cones or the like 
being arranged one behind the other with at least one of the valve seats, 
within the framework of the manufacturing tolerances of the axial 
positions of the sealing cones on the single valve needle, being disposed 
or supported in an axially movable and flexibly elastic manner in a valve 
seat body. 
To provide for a communication between the two pressure chambers, at least 
one bore is provided which may be disposed in the valve seat body so that 
the two pressure chambers are connected when the valve needle is lifted. 
In accordance with yet additional features of the present invention, the 
two valve needles, located concentrically with respect to one another, are 
adapted to execute a definite relative travel with respect to each other 
with an opening pressure of an outer valve needle being lower than that of 
an inner valve needle and the inner valve needle projecting out of the 
open end of the outer valve needle in a sealing manner. The projecting end 
of the inner valve needle may be further guided centrally through the 
valve seat of the outer valve needle and, in a sealing manner, through a 
bore in the valve seat body to a lower pressure chamber and the valve seat 
of the inner valve needle. The projecting end of the inner valve needle 
may be provided with a hollow bore and have a cross bore in a vicinity of 
an axial position of the end of the outer valve needle. The cross bore of 
the inner valve needle may be openable and closable by an end of the outer 
valve needle during the relative travel of the two valve needles in the 
manner of a spool valve. Moreover, when the valve needle has been lifted, 
bores in the projecting end of the inner valve needle may constitute the 
only flow connection between the two pressure chambers. 
The injection valve of the present invention may be constructed as a 
multi-port valve or as a pintle-type valve and, as a pintle-type valve, 
may be constructed as a so called conversion nozzle valve with a 
constricted needle tip. 
Furthermore, in the use of the injection valve of the present invention, 
different fuels or different fuel components may be supplied to the two 
pressure chambers. The fuels or fuel components may have different 
ignition performances and/or different soot-producting characteristics. 
Moreover, one fuel may be supplied to one of the pressure chambers and a 
liquid, insoluble and/or immiscible, environmentally safe 
exhaust-gas-improving fuel additive may be added to the other pressure 
chamber. It is also possible to supply, for example, a diesel fuel to the 
pressure chamber which opens first and a gasoline to the pressure chamber 
which opens last. Preferably, the injection valve is disposed so as to 
directly inject the fuel mixture or fuel components into a working chamber 
of the internal combustion engine. 
Accordingly, it is an object of the present invention, to provide an 
injection valve arrangement for high-pressure injection of fuel into a 
working chamber of an internal combustion engine which avoids, by simple 
means, shortcomings and disadvantages encountered in the prior art. 
Another object of the present invention resides in providing an injection 
valve arrangement for high-pressure injection of a fuel into a working 
chamber of an internal combustion engine which is capable of 
simultaneously supplying a mixture of two fuels and/or fuel components to 
the engine. 
Yet another object of the present invention resides in providing an 
injection valve arrangement for high-pressure injection of a fuel into a 
working chamber of an internal combustion engine which insures a 
homogeneous mixing of the two fuels and/or fuel components during an 
injection process. 
A further object of the present invention resides in providing a method of 
operating an internal combustion engine wherein different fuels and/or 
fuel components are supplied to two distinct pressure chambers of an 
injection valve. 
A still further object of the present invention resides in providing a 
method of operating an internal combustion engine wherein fuels having 
different ignition performances and/or soot-producing characteristics are 
supplied to a working chamber of the engine by way of a single injection 
valve. 
Another object of the present invention resides in providing an injection 
valve arrangement for high-pressure injection of a fuel into a working 
chamber of an internal combustion engine which is simple in construction 
and therefore inexpensive to manufacture. 
A further object of the present invention resides in providing an injection 
valve arrangement for high-pressure injection of a fuel into a working 
chamber of an internal combustion engine which functions reliably under 
all operating conditions.

Referring now to the drawings wherein like reference numerals are used 
throughout the various views to designate like parts and, more 
particularly, to FIG. 1, according to this figure, an injection valve 
generally designated by the reference numeral 1 is mounted in a cylinder 
head 2 of an internal combustion engine (not shown) which is constructed 
for multi-fuel mixed operation. For this purpose, a double fuel injection 
pump generally designated by the reference numeral 3 is provided which 
includes a first piston row 4 and a second piston row 5 with a regulator 6 
being mounted on the fuel injection pump 3 for selectively displacing or 
holding control rods 7, 8 for the respective piston rows 4, 5 in 
predetermined set positions as a function of the rpm and load of the 
internal combustion engine. Two fuel tanks 9, 10 as well as two fuel pumps 
12 are provided which correspond to the multi-fuel mixed operation of the 
internal combustion engine. The fuel pumps 12 and tanks 9, 10 supply the 
double fuel injection pump 3 with different fuels and/or fuel components 
at a specified pre-feed pressure. 
Two separate injection lines 13, 14 are provided for supplying two fuels 
and/or fuel components to the injection valve 1. The separate injection 
lines 13, 14 terminate at line connectors 37, 38 of the injection valve 1. 
Despite very close manufacturing tolerances, a leakage of fuel inside the 
injection valve on the low-pressure side of the valve needles can never 
truly be completely avoided; therefore, a mixture of two fuels and/or fuel 
components collects on the low-pressure side of the valve needles. An 
oil-leak connection is provided to carry away the mixture of the fuels 
from which oil-leak connection the fuel mixture may be guided into a 
collecting tank 11 for the fuel mixture by way of a return line 15. 
In the construction of FIGS. 1 and 2, the injection valve 1 is constructed 
as a double-needle valve and includes two pressure chambers 25, 26 which, 
in a closed position of the injection valve 1, are separated from each 
other. One fuel or a component of the fuel is supplied to each of the two 
pressure chambers 25, 26 by way of separate pressure ducts or bores 31, 
32. 
As shown in FIGS. 1 and 2, the double-needle valve is composed of an outer 
valve needle 16 and an inner valve needle 18 disposed concentrically 
within the outer valve needle 16. The outer valve needle 16 is provided at 
its lower end with a sealing cone 21 adapted to cooperate with a valve 
seat 23 formed integrally with the valve housing. The lower end of the 
inner valve needle 18, projecting with play out of the outer valve needle 
16, is provided with a sealing cone 22 adapted to cooperate with a valve 
seat 24 of the lower pressure chamber 26. The injection valve 1 of FIGS. 1 
and 2, as with the injection valve of FIGS. 4 and 5, is constructed as a 
multi-port valve with a blind bore or hole 33 being located below the 
lowermost valve seat 24 and a plurality of orifice nozzles 34 
communicating with the blind bore 33. The blind bore 33 has a common flow 
cross-section for both pressure chambers 25, 26 wherein the two fuels 
and/or fuel components to be injected are mixed intimately with one 
another by the high turbulence. 
The two valve needles 16, 18 are each pressed onto their corresponding 
valve seats 23, 24 by separate valve springs 27, 28. Hydraulic pressure of 
the fuel and/or fuel components in the pressure chambers 25, 26 enables 
the valve needles 16, 18 to be lifted off their respective valve seats 23, 
24 against a force of the springs 27, 28 and against the flow direction 
designated by the arrow 30. When the valve needles 16, 18 are in a raised 
position, the two pressure chambers 25, 26 are connected by a bore 46 
provided in the valve seat body 39. 
The injection valves illustrated in FIGS. 1-4 are constructed for a 
simultaneous lifting and closing of the valve needles 16, 18. However, 
since the valve needles 16, 18 must close in a leak-tight manner against 
very high pressures, since the exact relative positions of the two valve 
seats 23, 24 are subject to certain variations as a result of differences 
in manufacturing, and since this relative position in a specific 
individual injection valve can also change in the course of time as a 
function of operation of the injection valve, it is sometimes difficult to 
insure a tight seal of both of the valve seats 23, 24, rigidly mounted in 
the valve seat body 39, with a common valve needle. 
For this reason, in the constructions of FIGS. 1-4, two valve needles 16, 
18 are provided and pressed against associated valve seats 23, 24 by 
separate springs 27, 28. To insure an approximately simultaneous lifting 
of the valve springs 27, 28, a stop flange 43, mounted on the inner valve 
needle 18, and a cap-shaped spring centering plate 48 pushed over the stop 
flange 43 for the outer valve needle 16 insures that only a small relative 
travel h or h' is possible in one direction of movement or the other. This 
small relative travel h or h' need only be slightly larger than the 
largest possible manufacturing tolerances for the two valve seats 23, 24 
with respect to their axial spacing. The actual absolute needle travel H 
performed by the two valve needles 16, 18, jointly, is determined by a 
stop surface or flange 43' on a spring centering plate 48' of the inner 
valve needle 18 with the surface 43' being adapted to abut an inner upper 
side or surface of a chamber accommodating the springs 27, 28. 
Briefly, the injection valve of FIGS. 1 and 2 operates as follows: 
Cams (not shown) are provided for driving the first and second piston rows 
4, 5 of the injection pump 3. The cams are constructed so that two 
opposite pistons in the respective piston rows 4, 5 begin to pump 
simultaneously. Likewise, the opening pressures of the two valve needles 
16, 18 are made equal to one another so that the two valve needles 16, 18 
are caused to be lifted at least approximately simultaneously. The stop 
flange 43 also insures a joint lifting of the two valve needles 16, 18 if 
one of the needles should stick. The fuels or the fuel mixtures delivered 
through the ducts 31, 32 enter the blind bore 33 with high turbulence and 
are mixed intimately thereat with one another prior to entering the 
working chamber of the engine. The injected amounts of the two individual 
fuels and/or fuel components may be independently controlled by suitable 
conventional control means. When injection of the two fuels and/or fuel 
components begins simultaneously, such can only be accomplished by one of 
the two fuels being injected for a longer period of time than the other. 
When no more fuel is being pumped into one of the two pressure chambers 
25, 26 because delivery has ceased, the corresponding opening pressure 
will be maintained by the other fuel which continues to be fed so that 
both valve needles 16, 18 remain open. Even if one of the two fuels and/or 
fuel components is not to be injected at all in certain operating states 
of the internal combustion engine, the opening pressure of both valve 
needles 16, 18 is overcome jointly by the pressure of the one fuel or fuel 
components which continues to be injected. In this type of operation, the 
injection pressure is higher than normal. 
It is advantageous to supply the fuel which is to be injected alone 
temporarily by way of the pressure chamber 25 of the outer valve needle 16 
because the hydraulic pressure on the outer valve needle 16 alone 
necessarily moves both valve needles 16, 18. If the fuel for pre-injection 
is a fuel with high ignition performance such as, for example, diesel 
fuel, and the fuel for main injection is one with a short ignition lag 
such as, for example, gasoline, the construction of the injection valve 1 
for direct injection produces relative gentle combustion. 
In FIG. 3, the injection valve generally designated by the reference 
numeral 1' is provided with a modified valve seat body 40 as well as a 
valve needle 19 having a slightly different configuration from the valve 
needle 18 of the injection valve 1. However, both injection valves 1, 1' 
are in the form of a pintle-type valve with one pintle-type nozzle 35 in 
the valve seat body and one needle tip 36 in the inner valve needle 19. An 
annular gap formed between the pintle-type nozzle 35 and the needle tip 36 
constitutes a common spray cross-section in which the two fuels can be 
mixed intimately with each other prior to entering the working chamber of 
the engine. 
The needle tip 36 is markedly constricted and, in fact, is nearly 
mushroom-shaped thereby forming a so called conversion nozzle with the 
injection stream being converted to a widespread spray cone. Such 
construction results in a good distribution of the two fuels and/or fuel 
components in the working or combustion chamber of the engine even with 
low air turbulence and/or direct injection. In all other respects, the 
injection valve 1' of FIG. 3 corresponds to that shown in FIGS. 1 and 2. 
As shown in FIG. 4, an injection valve generally designated by the 
reference numeral 1" is provided wherein, instead of two needles disposed 
concentrically, one within the other, only a single valve needle is 
provided having two sealing cones 21, 22 constructed in the same manner as 
the double needle valves discussed hereinabove. Since only one valve 
needle 17 is provided to accomplish a double sealing function, only a 
single valve spring 29 is likewise required. 
To compensate for manufacturing tolerances, for which purpose the two 
needle valves were provided in the other embodiments, a movable valve seat 
ring 44 is inserted in a sealing manner in the valve seat body 41. The 
valve seat ring 44 is supported in a flexibly elastic manner by a spring 
washer 45 which has a very hard spring characteristic. The flexibly 
elastic mounting of the upper valve seat 23 means that both valve seats 
23, 24 can be sealed in a leak-tight manner even against higher pressures 
by way of only the single valve needle 17. 
The elastic mounting of the valve seats 23, 24 in the valve housing 
constitutes, so to speak, a reversal of the elastic mounting of the 
sealing cone 22 relative to the outer valve needle 16. The injection valve 
1" of FIG. 4 functions in the same manner as described hereinabove with 
respect to the injection valves of FIGS. 1-3. Thus, for example, as shown 
in FIG. 8, the pintle valve construction of FIG. 3 may be utilized with 
the movable valve seat ring of 44 supported in a flexible elastic manner 
by a spring washer 45, as shown in FIG. 4. 
FIGS. 5-7 provide an example of an injection valve for multifuel mixed 
operation in which a different fuel and/or fuel components are adapted to 
be injected primarily sequentially. For this purpose, the two compression 
chambers 25, 26 of the injection valve generally designated by the 
reference numeral 1''' are separated from one another hydraulically. An 
inner valve needle 20 is guided in a sealing manner through a bore 55 
provided in the valve seat body 42 as far as the lower valve seat 24. An 
end 51 of the inner valve needle 20 projecting beyond the end 50 of the 
outer valve needle 16 is likewise guided in a sealing manner in an 
interior of the outer valve needle 20, in contrast to the embodiments 
shown in FIGS. 1-3, wherein the lower end of the valve needle has a 
certain amount of play radially and therefore can compensate for a poor 
fit. 
The projecting end 51 of the inner valve needle 20 in the injection valve 
1''' has a hollow bore 52 which extends lengthwise and a cross bore 53 
arranged in a vicinity of the end 50 of the outer valve needle 16. A 
circumferential groove 54 is also provided in a vicinity of the cross bore 
53. The axial position in groove 54 is such that, when both valve needles 
16, 20 are in a closed position, the groove 54 is completely covered by 
the outer valve needle 16. 
In the construction of FIGS. 5-7, the injection valve 1''' is provided with 
a relatively large travel path S between the two valve needles 20, 16. Two 
stop shoulders 47, 47a are provided on a spring plate generally designated 
by the reference numeral 48a for the outer valve needle 16 with one stop 
47a adapted to strike or come into abutting engagement with the valve 
housing after travelling distance S and the other stop 47 striking or 
engaging a spring plate 49 of the inner valve needle 20. 
The valve springs 27, 28 in the injection valve 1''' are designed and 
constructed so that the outer valve needle 16 opens first. In cooperation 
with the corresponding double injection pump, for example, the pump 3, the 
outer valve needle 20 may also be caused to open first by virtue of the 
fact that delivery of the fuel to be fed to the compression chamber 25 is 
set to begin earlier than the start of delivery of the other fuel. 
As shown most clearly in FIGS. 6 and 7, the operation of the injection 
valve 1''' is as follows: 
After delivery of the fuel to the injection valve begins, the fuel is 
supplied by way of the duct 31 to the compression chamber 25. After the 
pressure in the chamber 25 exceeds the opening pressure for the outer 
valve needle 16, the valve needle 16 is raised so that its sealing cone 21 
lifts off the valve seat 23 thereby exposing the groove 54. Fuel may then 
be sprayed by way of bores 52, 53, blind bore 55, and orifice nozzles 34 
into the working chamber of the engine. As long as the outer valve needle 
16 is still moving upward and has not yet covered the relative travel 
distance S, the inner valve needle 20 remains closed. 
Assuming that a corresponding opening pressure has not yet developed in the 
lower pressure chamber 26, a situation which might be caused by the higher 
opening pressure of the inner valve needle 16 or a delayed start in 
delivery of the corresponding pump piston feeding the fuel to the lower 
pressure chamber 26, as long as the outer valve needle 16 has opened, and 
as long as the inner valve needle 20 has remained closed at the same time, 
as shown in FIG. 6, only one fuel or fuel component will enter into the 
working chamber of the engine. When the outer valve needle 16 has reached 
its maximum opening as determined by the engagement between the shoulder 
47a and the corresponding edge of the valve housing, in which position 
stop shoulders 47 simultaneously strike spring plate 49, lifting the inner 
valve needle 20 off its valve seat 24, the valve needle 20 opens as well. 
It is assumed in this connection that the corresponding opening pressure 
has developed in the lower pressure chamber 26 in the meantime. 
As apparent from the above description, during a certain transition phase 
both fuels and/or fuel components are simultaneously injected into the 
working chamber of the engine. As the inner valve needle 20 continues to 
open, the groove 54 is again gradually controlled by the outer valve 
needle 16 which remains in its highest lifted position or by the end 50 of 
the valve needle 16. This causes the feed of fuel by way of the duct 31 to 
be interrupted and only the fuel fed through the injection duct 32 enters 
the working chamber of the engine. A certain drop in pressure in the 
injection lines corresponding to the duct 31 or chamber 25 can be effected 
by an appropriate dimensioning of the play between the bore 55 and the 
valve needle end 51. 
As the supply of fuel being fed by way of the duct 31 decreases, the outer 
valve needle 16 sinks or drops back onto its valve seat 23. The inner 
valve needle may then still be opened completely as a function of the 
injection time of the fuel supplied by way of the duct 32. After delivery 
of this fuel ceases, the inner valve needle 20 also returns to the valve 
seat 24 so as to result in a position such as illustrated in FIG. 5. 
As can be appreciated, the successive injection of different fuels is 
especially advantageous in a mixed diesel fuel/gasoline form of operation 
of an engine. The corresponding internal combustion engine is then 
equipped as an air-compressing internal combustion engine with internal 
mixture formation which compresses the air to a point above the 
spontaneous ignition temperature of diesel fuel. By means of an injection 
valve 1''' such as illustrated in FIGS. 5-7, diesel fuel may first be 
supplied or injected by way of the lines or ducts 13, 31. Ignition in the 
working chamber of the internal combustion engine would then take place. 
Gasoline could then be injected by way of the lines or ducts 14 and 32 
with a certain overlap in time with the gasoline then being ignited by the 
already burning diesel fuel. Since the gasoline is subject only to a 
slight delay in ignition because of the high temperature prevailing in the 
working chamber of the engine and because of the considerable tendency of 
gasoline toward evaporation, the gasoline injected through the duct 32 and 
pressure chamber 26 burns as fast as it is injected, thereby resulting in 
a relatively gentle combustion process. 
Furthermore, the partial injection of diesel fuel, which ignites 
spontaneously, allows operation of the engine with a high excess of air. 
This fact, as well as the high compression, produces good complete 
combustion and hence good utilization of the fuel as well as increasing 
the quality of the exhaust gas as far as carbon monoxide content and 
hydrocarbon content are concerned. Since the internal combustion engine is 
operated primarily on gasoline at full load, better soot-producing 
characteristics of this fuel means that a soot emission from the 
corresponding internal combustion engine will be very low. 
The use of the injection valves according to FIGS. 1-4 permits the 
soot-producing characteristic of diesel fuel to be improved, especially at 
full load by the fact that a liquid fuel additive may be mixed with the 
diesel fuel as a function of load and in a certain cycle as a fuel 
component at least in the upper and high load range by way of one of the 
two pressure chambers 25, 26. The additive may have a soot-reducing 
characteristic and be environmentally safe in and of itself. 
Advantageously, the fuel additive itself has fuel characteristics so that 
it could supply energy. The addition of a fuel additive of this kind with 
the aid of an injection valve in accordance with the present invention has 
the advantage that the mixing ratio can be varied as a function of load 
and also immiscible fuel additives could be readily utilized. 
While we have shown and described several embodiments in accordance with 
the present invention, it is understood that the same is not limited 
thereto, but is susceptible of numerous changes and modifications as known 
to one having ordinary skill in the art, and we therefore do not wish to 
be limited to the details shown and described herein, but intend to cover 
all such modifications as are encompassed by the scope of the appended 
claims.