Fuel injection valve

A fuel injection valve comprising a front attachment in whose wall a blocking element is displaceably supported; on its slide segment toward an air chamber, the pressure in the inlet tube upstream of a throttle valve prevails, while in the opposite direction the intake tube pressure downstream of the throttle valve is operative. If there is a sufficient pressure difference, the blocking element is displaced to the left far enough that it blocks at least one injection port on the fuel injection valve and blocks one guide conduit in the front attachment. As a result, only the one open inlet valve of one cylinder of the engine is supplied with fuel, via the at least one open injection port and the open guide conduit. The fuel injection valve is especially suitable for fuel injection in mixture-compressing internal combustion engines with externally supplied ignition.

PRIOR ART 
The invention is based on a fuel injection valve. A fuel injection valve is 
already known (U.S. Pat. No. 4,982,716) in which the fuel streams, aimed 
at the various inlet conduits of a cylinder, are always ejected 
simultaneously. This has the disadvantage however, that whenever in 
certain operating states of the internal combustion engine, such as idling 
and lower partial load, one of the at least two inlet valves is turned off 
to improve engine operation with respect to fuel consumption and exhaust 
emissions, at least one of the separate fuel streams undesirably hits the 
closed inlet valve. 
Two separate fuel streams are generated in this fuel injection valve, 
because downstream of the valve seat a single fuel stream strikes an 
impact face and is split into two separate fuel streams by a stream 
splitter. 
From European Patent EP 0 242 978, a fuel injection valve is also known 
that has a perforated disk, downstream of the valve seat face, in which 
six injection ports are provided; the individual streams each emerging 
from three injection ports are aimed toward one another in such a way that 
two separate fuel streams are produced, and each fuel stream is aimed into 
one inlet conduit of a cylinder of the engine. In this fuel injection 
valve as well, the fuel is injected into the two inlet conduits of each 
engine cylinder via the two separate fuel streams even if one of the inlet 
valves is closed. 
A fuel injection valve is also known (SAE Technical Paper Series 920 294, 
1992; Development of Air-Assisted Injector System), in which an adapter 
with a stream splitter is provided, by means of which fuel injected from 
the injection valve is split into two fuel streams, to which air for 
preparation is added via air conduits; the air is controllable by a 
control valve that branches off from a bypass line around the throttle 
valve in the engine intake tube. With one closing member, the control 
valve opens and closes the air line to the fuel injection valves, and with 
another closing member it closes the bypass line around the throttle 
valve. 
ADVANTAGES OF THE INVENTION 
The fuel injection valve according to the invention has the advantage over 
the prior art that in a simple way, in certain engine operating states 
such as idling and lower partial load, fuel is delivered to each cylinder 
of the engine only via the open inlet valve or valves, while in the these 
certain operating states, no fuel is prestored upstream of the closed 
inlet valves or valve. As a result, not only fuel consumption but also the 
proportion of pollutants in the exhaust gas can be reduced, and the 
performance at transitions between operating states can be improved. 
By means of the provisions recited herein, advantageous further features of 
and improvements to the fuel injection valve disclosed hereinafter are 
possible. 
It is especially advantageous to dispose a front attachment, in which the 
blocking element is supported movably, on the fuel injection valve. Hence 
there is no need to modify the construction of existing fuel injection 
valves; a suitable front attachment need merely be adapted to the 
particular fuel injection valve. It is also advantageous to displace the 
blocking element by means of air that is delivered to the fuel injection 
valve to prepare the injected fuel. It is also advantageous to insert a 
control valve into the air line to the blocking element, by which valve 
the air line can be closed partway or entirely, in order to actuate the 
blocking element exactly in accordance with particular requirements of the 
engine.

DESCRIPTION OF THE EXEMPLARY EMBODIMENTS 
In FIG. 1a, a cylinder of a mixture-compressing internal combustion engine 
with externally supplied ignition is shown; it has at least one inlet 
opening 2, which is opened or closed by an inlet valve 3. To improve the 
efficiency and reduce the exhaust gas components of the engine, especially 
by lean operation and charge stratification, the cylinders of the engine 
are today often provided with two or more inlet valves and outlet valves. 
FIG. 1b shows a cylinder with two inlet openings 2, in which for the sake 
of simpler illustration the inlet valves 3 have been left out. A spark 
plug 5 serves to ignite the fuel-air mixture compressed in the cylinder 1, 
and two outlet openings 6, which are controlled by outlet valves not 
shown, lead to the exhaust line 7 of the engine. Separated by a partition 
9, one inlet conduit 10 leads to each inlet opening 2; the two inlet 
conduits 10 unite upstream of the partition 9 to form one single intake 
tube 11 associated with the respective cylinder. Protruding partway into 
the individual intake tube 11 is an injection end of a fuel injection 
valve 13, which injects two separate fuel streams 14; one fuel stream 14 
is aimed in the direction of one inlet conduit 10 or one inlet opening 2. 
As described in conjunction with FIG. 1b, in FIG. 1a as well the cylinder 
1 has two inlet valves 3 and two inlet openings 2, which are supplied with 
fuel through a single fuel injection valve 13. In another embodiment, 
however, it is also possible for the cylinder 1 to have only a single 
inlet valve 3 and a single inlet opening 2, while the fuel injection valve 
13 is still embodied such that it injects at least two separate fuel 
streams in the direction of the inlet conduit 10 or inlet opening 2. The 
orientation of the separate fuel streams 14 can be selected very 
accurately and adapted to a favorable operating performance of the engine. 
The single inlet tube 11 originates at a distributor 15, from which the 
single intake tubes to the other engine cylinders, not shown, also branch 
off. Upstream of the distributor is the intake tube 17 with the throttle 
valve 18, which is actuatable by the vehicle driver by means of an 
accelerator pedal, not shown. Upstream of the throttle valve 18, an air 
bypass 19 branches off from the intake tube 17; a control valve 21 is 
disposed in the air bypass, and its control body 22 can assume various 
positions continuously in order to close the air bypass 17, make a 
connection from the air bypass to an air line 23 leading to the fuel 
injection valve 13, and then also make a connection from the air bypass 19 
to an inflow line 25, leading downstream of the throttle valve 18 to the 
intake tube 17, and finally to block off the communication with the air 
line 23 completely and keep only the communication with the inflow line 25 
open. By way of example, the control valve 21 is actuated by an electric 
motor and triggered by an electronic control unit 26 via electric lines. 
The triggering of the electromagnetically actuatable fuel injection valve 
13 is also effected by the electronic control unit 26 via electric lines. 
Measured values of engine operating parameters, such as the rpm 27, the 
load 28 in accordance with the rotational angle of the throttle valve 18, 
the engine temperature 29, the oxygen concentration 30 in the exhaust line 
7, and others, are supplied to the electronic control unit after having 
been converted into electrical signals. 
In FIGS. 2a, 2b and 2c, the control valve 21 of FIG. 1a, embodied as a 
rotary slide and for instance driven by an electric motor, is shown in 
simplified form once again in various control positions; the reference 
numerals chosen for FIG. 1a have been retained. The control body 22 
embodied as a rotary slide is rotatable by an electric motor, not shown, 
and in cross section takes the form of a segment of a circle with an 
indentation 32, which is bounded by a first sealing lip 33 and a second 
sealing lip 34 of the control body 22. Upon a clockwise rotary motion of 
the control body 22, the first sealing lip 33 is ahead and the second 
sealing lip 34 trails behind. The control body 22 is rotatably supported 
in a work chamber 36 with which the air bypass 19, the air line 23, and 
the inflow line 25 communicate. The air bypass 19, at its mouth into the 
work chamber 36, is bounded by a first sealing face 37 and, following it 
in the clockwise direction, a second sealing face 38. The second sealing 
face 38 at the same time defines the mouth of the air line 23 into the 
work chamber 36, which is bounded in the clockwise direction by a third 
sealing face 39. In FIG. 2a, the control body 22 assumes a position in 
which the first sealing lip 33 partly covers the second sealing face 38 
and the third sealing face 39, and the second sealing lip 34 partly covers 
the first sealing face 37, so that the communication from the air bypass 
19 to the air line 23 and to the inflow line 25 is interrupted. If the 
control body 22, in idling and lower partial-load operation of the engine, 
is now rotated clockwise, then the second sealing lip 34 initially 
continues to cover the first sealing face 37, while the first sealing lip 
33 moves away from the second sealing face 38 and thus, via the 
indentation 32, opens up a communication from the air bypass 19 to the air 
line 23. FIG. 2b shows a position of the control body 22 in which a flow 
communication from the air bypass 17 to the air line 23 is opened by the 
control body 22, yet the second sealing lip 34 still just covers the first 
sealing face 37 enough that there is no flow of air from the air bypass 19 
to the inflow line 25. If the control body 22 is rotated clockwise beyond 
the position shown in FIG. 2b, then the second sealing lip 34 moves away 
from the first sealing face 37, so that now, in addition to the flow from 
the air bypass 19 to the air line 23, the flow path from the air bypass 19 
to the inflow line 25 is also opened. Such a position of the control body 
22 is shown in FIG. 2c. To assure, in the event of an error in the 
electronic control unit or in the electric lines or electric motor, that 
the engine will continue to be operated in a so-called emergency mode, it 
may be expedient, by means of a restoring spring, not shown, and beginning 
at a position in accordance with FIG. 2a, to rotate the control body 22 
counterclockwise far enough that either the first sealing lip 33 moves out 
of contact with the third sealing face 39, or the second sealing lip 34 
moves out of contact with the first sealing face 37, or both the first 
sealing lip 33 moves out of contact with the third sealing face 39 and the 
second sealing lip 34 also moves out of contact with the first sealing 
face 37, so that a hydraulic communication is established either from the 
air bypass 19 to the air line 23 or to the inflow line 25, or from the air 
bypass to both of these lines. 
In FIG. 3, an example of an otherwise already known fuel injection valve 13 
for fuel injection systems of mixture-compressing internal combustion 
engines with externally supplied ignition is shown in part; on its 
injection end 41, it has a front attachment 42, made for instance of 
plastic. The injection end 41 of the fuel injection valve 13 is embodied 
in a nozzle body 43 that is provided with a longitudinally extending guide 
conduit 45 in which a movable valve closing member 46, such as a valve 
needle, is slidably supported. Remote from the injection end 41, the guide 
conduit 45 changes over into a valve seat face 47, with which the valve 
closing member 46 cooperates. In the flow direction, the valve seat face 
47 changes over into an outflow opening 49, which extends as far as a 
nozzle body end face 50. In the exemplary embodiment shown, an injection 
port disk 51 rests on the nozzle body end face 50 and is tightly connected 
to it, for instance by an encompassing sealing seam radially spaced apart 
from the outflow opening 49. Where the outflow opening 49, in the 
exemplary embodiment of FIG. 3, is covered, there are for instance at 
least two injection ports 53 in the injection port disk 51; they extend as 
far as a lower end face 54 of the injection port disk 51. It is not a 
requirement that there be at least two injection ports 53 in the injection 
port disk 51. In a manner not shown, it is also possible for there to be 
only one injection port 53 in the injection port disk 51; then the fuel 
emerging from the one injection port is divided downstream into two 
individual streams by a stream splitter, as is already known from the 
known fuel injection valves described in the introduction to this 
specification. Nor is the injection port disk 51 a requirement; it is also 
possible to use a fuel injection valve in which there is no injection port 
disk, but instead in which the fuel is injected via the outflow opening 49 
or at least two injection ports adjoining the outflow opening 49 and 
embodied on the nozzle body end face 50. The actuation of the fuel 
injection valve is effected in a known manner, such as 
electromagnetically. For axially moving the valve closing member 46 and 
hence for opening the fuel injection valve counter to the spring force of 
a restoring spring not shown, or closing the fuel injection valve, an 
electromagnetic circuit is used, which has a magnet coil, armature and 
core, not shown. The armature is connected to the end of the valve closing 
member 46 remote from the valve seat face 47 and is oriented toward the 
core. 
The front attachment 42 for instance comprises a stepped tubular air guide 
body 55 and an injection body 57. The injection body 57 is cup-shaped, 
with a bottom 58 that is adjoined by an annular rim 59 surrounding the 
injection end 41 of the fuel injection valve 13. An encompassing detent 
groove 61 is formed on the injection end 41 of the fuel injection valve 
13; a detent protrusion extending at least partway around engages this 
groove and thus fixes the injection body 57 to the injection end 41 of the 
fuel injection valve. An elastic sealing ring 65, on which a stepped inner 
wall 66 of the air guide body 55 rests tightly with radial pressure, is 
disposed in an annular groove 63 provided on the circumference of the 
injection body 57. The air guide body 55 extends axially beyond the 
annular rim 59 and partway beyond the housing, on which it rests in sealed 
fashion, in a manner not shown. The inner wall 66 of the air guide body 55 
is radially spaced apart from the injection body 57 and from the housing 
of the fuel injection valve, except for the sealed points of the sealing 
ring 65 and at the periphery of the housing of the fuel injection valve 
13, so that between the inner wall 66 and the exterior of both the fuel 
injection valve and the annular rim 59 an annular air chamber 67 is 
formed, which communicates with the air line 23 via an air fitting 69. 
Axially approximately in the region of the bottom 58 of the injection body 
57, an annular groove 70 is formed on the circumference of the air guide 
body 55; in it, an elastic sealing ring 71 is provided, which on insertion 
of the fuel injection valve 13, with the front attachment 42 disposed on 
it, into a valve conduit 73 (FIG. 1a) of the wall of the single intake 
tube 11 seals off the intake tube atmosphere from the ambient atmosphere 
outside. The bottom 58 of the injection body 57 has a dome 74, rising in 
the direction of the injection port disk 51; between the end face 75 of 
the dome toward the injection port disk 51 and the lower end face 54 of 
the injection port disk, a gap 76 is formed. Beginning at the end face 75 
of the dome 74, at least two guide conduits 78 extend through the bottom 
58 of the injection body 57, extending approximately in alignment with the 
associated injection ports 53 and inclined such that the distance from a 
longitudinal valve axis 79 and the distance from one another become 
greater in the flow direction. In the exemplary embodiment shown, two 
guide conduits 78 are provided; through each guide conduit, a fuel stream 
14 emerging from one of the injection ports 53 is injected as indicated by 
the dot-dashed lines. However, each fuel stream 14 may be formed by 
combining two or more individual streams emerging from individual 
injection ports. It is also possible for at least one third guide conduit 
78 to be provided in the injection port 57, in order to form a further 
fuel stream 14. Crosswise to the longitudinal valve axis 79, a slide 
conduit 80 penetrates the annular rim 59 of the injection port 57; in this 
conduit, a sliding segment 82 of a blocking element 83 is supported 
substantially tightly but displaceably. The blocking element 83 also has a 
tonguelike land segment 84, which is connected to the rectangular 
block-shaped slide segment 82 and on which a sealing segment 86 is 
embodied. A dome groove 87 extends open toward the end face 75, 
approximately from the longitudinal valve axis 79 to the circumference of 
the dome 74; this groove is aimed at the land segment 84, and the land 
segment 84 rests on this groove with its lower face 94 remote from the 
injection port disk 51, specifically in its nonblocking outset position, 
such that it does not protrude into the guide conduit 78. In this outset 
position, the sealing segment 86 embodied remote from the dome groove 87 
is also located in a position in which, while it does rest on the lower 
end face 54 of the injection port 51, nevertheless it does not cover any 
injection port 53. Connected to the land segment 84, for instance facing 
one another, are two spring arms 88, which are slidably supported in guide 
grooves 90 formed in the annular rim, as shown in FIG. 4. The spring arms 
88 effect a restoring force, which counteracts a displacement motion of 
the blocking element from right to left in terms of FIGS. 3 and 4. The 
displacement motion of the blocking element 83 is effected by the force of 
air whenever the compressive force on the slide segment 82 of the air 
located in the air chamber 67 is greater than the sum of the forces of the 
spring arms 88 and the compressive force of the air that acts on the 
blocking element 83 in the in interior of the injection port 57 from the 
single intake tube 11 via the guide conduits 78 and the gap 76. By a 
suitable selection of the spring force of the spring arms 88, it can now 
be attained that a displacement of the blocking element 83 to the left 
into its position that blocks at least one injection port 53 and one guide 
conduit 78 occurs only whenever the difference in air pressure, in engine 
idling and lower partial load operation, between the single intake tube 11 
and the intake tube 17 upstream of the throttle valve 18 is great enough 
for a displacement. As shown in FIG. 1a, the air chamber 67 communicates 
with the intake tube 17 upstream of the throttle valve 18 and is thus at 
virtually atmospheric pressure. If to increase engine performance the 
throttle valve 18 is rotated more strongly in the opening direction, then 
the pressure downstream of the throttle valve 18 and thus also in the 
single intake tubes 11 rises, and as a result the restoring force on the 
blocking element 83 is increased, and the blocking element is shifted to 
the right into its outset position, so that the fuel can again be injected 
unhindered via all the injection ports 83. In order to define an exact 
transition point from the blocking position of the blocking element 83 to 
its outset position and hence from the injection of a single fuel stream 
to the injection of at least one further fuel stream, and vice versa, it 
is expedient to dispose a control valve in the air line 23. Such a control 
valve is already shown in FIGS. 1a and 2a-2c. Beginning with the blocking 
position of FIG. 2a, the control valve 21, until it reaches its position 
shown in FIG. 2b, opens the air bypass 19 continuously to the air line 23, 
and as a result an adequately strong air force prevails at the blocking 
element 83 in order to displace the blocking element toward the left, into 
its position that interrupts at least one injection port 83 and thus one 
fuel stream. If the control valve 21 is rotated onward clockwise, beyond 
its position shown in FIG. 2b, then the air pressure in the inlet conduit 
10 rises, and the blocking element 83 is displaced to the right into its 
opening position. The actuation of the blocking element 83 by air in the 
manner described represents merely one possibility. In the same way it is 
possible to dispense with the air actuation described, and to actuate the 
blocking element 83 directly by means of an electromagnet 91, shown in 
dashed lines in FIG. 4, that is triggered by the electronic control unit 
26. If the blocking element 83 is in its blocking position, then a 
lengthening of the duration of injection by the fuel injection valve is 
controlled via the electronic control unit 26. 
In the ensuing FIGS. 5-8, the same elements and elements functioning the 
same are identified by the same reference numerals. FIGS. 5 and 6 show the 
exemplary embodiment of FIGS. 3 and 4, with a blocking element 83 located 
in the blocking position, that is, its left-hand position, in which it 
thus blocks at least one injection port 53 and one guide conduit 78. The 
arrows 92 indicate the air flow, which from the air chamber 67 moves past 
the slide segment 82, displaced out of the slide conduit 80 into the 
interior of the injection body 57, to reach the gap 76, where in the 
nonblocked left-hand guide conduit 78, it meets the fuel stream 14 
injected through the at least one nonblocked injection segment and is 
injected with it in a preparing way. 
FIGS. 7 and 8, like FIGS. 5 and 6, show a fuel injection valve with the 
front attachment 42 described and with a blocking element 83 located in 
the blocking position; however, in the embodiment of FIGS. 7 and 8 the 
dome 74 is so high that it rests on the lower end face 54 of the injection 
port disk 51 outside the dome groove 87, while between the lower face 94 
of the land segment 84 and the dome groove 87 an axial groove gap 95 is 
formed, by way of which the air flowing from the air chamber 67 into the 
interior of the injection body 57, in the blocking position of the 
blocking element 83, can flow into the guide conduit 78 associated with 
the blocked injection port 53. Such an embodiment is expedient whenever 
the injected fuel stream is intended to be a "hard" cord-shaped stream 
(pencil stream), or in other words with a very small stream cone angle. 
The foregoing relates to preferred exemplary embodiments of the invention, 
it being understood that other variants and embodiments thereof are 
possible within the spirit and scope of the invention, the latter being 
defined by the appended claims.