Information
-
Patent Grant
-
6651626
-
Patent Number
6,651,626
-
Date Filed
Friday, March 15, 200222 years ago
-
Date Issued
Tuesday, November 25, 200320 years ago
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Inventors
-
Original Assignees
-
Examiners
Agents
-
CPC
-
US Classifications
Field of Search
US
- 123 446
- 123 447
- 123 467
-
International Classifications
-
Abstract
The fuel injection apparatus for internal combustion engines has one fuel pump for each cylinder of the engine, which pump has a pump piston, driven by the engine in a reciprocating motion, that defines a pump work chamber to which fuel is delivered from a fuel tank and which communicates with a fuel injection valve that has an injection valve member by which at least one injection opening is controlled and which is movable in an opening direction counter to a closing force by the pressure generated in the pump work chamber, by means of a first electrically controlled control valve, a communication of the pump work chamber with a diversion chamber is controlled, and by means of a second electrically controlled control valve, the pressure prevailing in a control pressure chamber of the fuel injection valve is controlled, by which the injection valve member is urged at least indirectly in the closing direction. The diversion chamber is a pressure reservoir, in which an elevated pressure, compared to the pressure prevailing in the fuel tank, is maintained.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention is based on a fuel injection apparatus for internal combustion engines having a fuel pump for each cylinder of the engine.
2. Description of the Prior Art
One fuel injection apparatus, known from European Patent Disclosure EP 0 957 261, has one fuel pump for each cylinder of the engine, which pump has a pump piston, driven by the engine in a reciprocating motion, that defines a pump work chamber to which fuel is delivered from a fuel tank. The pump work chamber communicates with a fuel injection valve, which has an injection valve member by which at least one injection opening is controlled and which is movable in the opening direction counter to a closing force by the pressure prevailing in the pump work chamber. A first electrically controlled control valve is provided, by which a communication of the pump work chamber with the fuel tank, as a diversion chamber, is controlled. A second electrically controlled control valve is also provided, by which the control pressure prevailing in a control pressure chamber is controlled, by means of which pressure the injection valve member is urged at least indirectly in the closing direction. A disadvantage of this known fuel injection apparatus is that because of the use of the pressureless fuel tank as a diversion chamber, the pressure in the pump work chamber and in the regions of the fuel injection apparatus communicating with it drops sharply upon the communication with a relief chamber, with the attendant risk of cavitation. Moreover, as a result the efficiency of the fuel injection apparatus is not optimal.
OBJECTS AND SUMMARY OF THE INVENTION
The fuel injection apparatus of the invention has the advantage over the prior art that because the pressure reservoir, in which an elevated pressure is maintained compared to the fuel tank, is used as a diversion chamber the risk of cavitation is reduced and moreover the efficiency is improved. In addition, pressure fluctuations in the fuel injection apparatus can be damped by the pressure reservoir.
One embodiment of the invention makes it possible to adjust the pressure in the pressure reservoir, for instance as a function of engine operating parameters.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be better understood and further objects and advantages thereof will become more apparent from the ensuing detailed description of preferred embodiments taken in conjunction with the drawings, in which:
FIG. 1
shows a fuel injection apparatus for an internal combustion engine schematically in a first exemplary embodiment;
FIG. 2
shows the fuel injection apparatus in a second exemplary embodiment;
FIG. 3
shows a course of a pressure at injection openings of a fuel injection valve of the fuel injection apparatus;
FIG. 4
is a detail of a modified version of the fuel injection apparatus; and
FIG. 5
is a detail of a further modified version of the fuel injection apparatus.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIGS. 1
,
2
,
4
and
5
show a fuel injection apparatus for an internal combustion engine of a motor vehicle. The engine is preferably a self-igniting internal combustion engine. The fuel injection apparatus is preferably embodied as a so-called pump-line-nozzle system and for each of the engine has one fuel pump
10
, one fuel injection valve
12
, and one line
14
connecting the fuel injection valve
12
to the fuel pump
10
. The fuel pump
10
has a pump piston
18
, guided tightly in a cylinder
16
and driven in a reciprocating motion by a cam
20
of a camshaft of the engine, counter to the force of a restoring spring
19
. In the cylinder
16
, the pump piston
18
defines a pump work chamber
22
, in which upon the supply stroke of the pump piston
18
, fuel is compressed at high pressure. By means of a feed pump
21
, fuel from a fuel tank
24
of the motor vehicle is delivered to the pump work chamber
22
. A check valve
23
that opens toward the pump work chamber
22
is disposed between the feed pump
21
and the pump work chamber
22
. The check valve
23
can also be omitted, in which case the communication, leading away from the cylinder
16
, between the pump work chamber
22
and the fuel tank
24
is opened and closed by a control edge of the pump piston
18
. A further check valve
25
, opening outward from the pump work chamber
22
, is disposed in the line
14
. The supply line from the feed pump
21
discharges between the pump work chamber
22
and the further check valve
25
.
The fuel injection valve
12
is disposed separately from the fuel pump
10
and communicates with the pump work chamber
22
via the line
14
. The fuel injection valve
12
has a valve body
26
, which may be embodied in multiple parts and in which an injection valve member
28
is guided longitudinally displaceably in a bore
30
. The valve body
26
, in its end region oriented toward the combustion chamber of the cylinder of the engine, has at least one and preferably a plurality of injection openings
32
. The injection valve member
28
, in its end region toward the combustion chamber, has a sealing face
34
, which for instance is approximately conical, and which cooperates with a valve seat
36
, embodied in the valve body
26
in its end region toward the combustion chamber; the injection openings
32
lead away from or downstream of this valve seat. In the valve body
26
, between the injection valve member
28
and the bore
30
, toward the valve seat
36
, there is an annular chamber
38
, which in its end region, remote from the valve seat
36
, changes over as a result of a radial widening of the bore
30
into a pressure chamber
40
surrounding the injection valve member
28
. At the level of the pressure chamber
40
, as a result of a reduction in its cross section, the injection valve member
28
has a pressure shoulder
42
. The end remote from the combustion chamber of the injection valve member
28
is engaged by a prestressed closing spring
44
, by which the injection valve member
28
is pressed toward the valve seat
36
. The closing spring
44
is disposed in a spring chamber
46
of the valve body
26
that adjoins the bore
30
. The spring chamber
46
is adjoined, on its end remote from the bore
30
, in the valve body
26
by a further bore
48
, in which a piston
50
that is joined to the injection valve member
28
is tightly guided. The piston
50
, with its face end remote from the injection valve member
28
, defines a control pressure chamber
52
in the valve body
26
. Embodied in the valve body
26
is a conduit
54
, into which the line
14
to the fuel pump
10
discharges and which itself discharges into the pressure chamber
40
.
In
FIG. 1
, the fuel injection apparatus is shown in a first exemplary embodiment. A communication
56
to the control pressure chamber
52
branches off from the conduit
54
. The fuel injection apparatus has a first control valve
60
, disposed near the fuel pump
10
, that can for instance be integrated with the fuel pump
10
. By means of the first control valve
60
, a communication
59
of the pump work chamber
22
of the fuel pump
10
with a diversion chamber
62
, embodied as a pressure reservoir, is controlled. Downstream of the check valve
25
, the communication
59
branches off from the line
14
. In the pressure reservoir
62
, an elevated pressure is maintained, compared to the pressure in the fuel tank
24
. Via a pressure limiting valve
64
, the pressure reservoir
62
communicates with a relief chamber, which for instance is the fuel tank
24
. By means of the pressure limiting valve
64
, the pressure in the pressure reservoir
62
is kept at least nearly constant, because this valve opens when the set pressure is reached, and fuel can flow out of the pressure reservoir
62
into the fuel tank
24
. If the engine has multiple cylinders, then a single common pressure reservoir
62
can be used for the fuel injection apparatuses of all the cylinders.
The first control valve
60
is electrically controllable and has an actuator
61
, which can be an electromagnet or a piezoelectric actuator and is electrically triggered and by which a valve member of the control valve
60
is movable. The first control valve
60
can be embodied as either pressure-balanced or not pressure-balanced. The first control valve
60
is embodied as a 2/2-way valve, by which in a first switching position the communication
59
with the pressure reservoir
62
is opened, and in a second switching position the communication
59
with the pressure reservoir
62
is interrupted. The control valve
60
is controlled by an electric control unit
66
as a function of engine operating parameters.
For controlling the pressure in the control pressure chamber
52
, a second control valve
68
is provided, by which a communication
70
of the control pressure chamber
52
with a relief chamber, such as the fuel tank
24
, is controlled. The second control valve
68
is electrically controllable and has an actuator
69
, which can be an electromagnet or a piezoelectric actuator and is triggered electrically and by which a valve member of the control valve
68
is movable. The second control valve
68
is preferably embodied as pressure-balanced, but it can also be not pressure-balanced. The second control valve
68
is embodied as 2/2-way valve, by which in a first switching position the communication
70
of the control pressure chamber
52
with the fuel tank
24
is opened, and by which in a second switching position the communication
70
of the control pressure chamber
52
with the fuel tank
24
is interrupted. A throttle restriction
58
is provided in the communication
59
of the control pressure chamber
52
with the conduit
54
, and a further throttle restriction
71
is provided, between the control pressure chamber
52
and the second control valve
68
, in the communication
70
of the control pressure chamber
52
with the fuel
24
. The second control valve
68
is likewise controlled by the control unit
66
. The control of the control valves
60
,
68
by the control unit
66
is effected as a function of engine operating parameters, such as rpm, load and temperature.
The mode of operation of the fuel injection apparatus in accordance with the first exemplary embodiment will now be explained. In the intake stroke of the pump piston
18
, fuel is pumped out of the fuel tank
24
into the pump work chamber
22
by the feed pump
21
, through the opened check valve
23
or through the communication opened by the control edge of the pump piston
18
. In the supply stroke of the pump piston
18
, the check valve
23
closes, or the communication is covered by the pump piston
18
and the check valve
25
opens, whereupon the first control valve
60
can be opened, so that the communication
59
with the pressure reservoir
62
is opened. If the fuel injection is to begin with a preinjection, then the first control valve
60
is closed by the control unit
66
, so that the communication
59
with the pressure reservoir
62
is interrupted, and high pressure can build up in the pump work chamber
22
. The pressure prevailing in the pump work chamber
22
is also operative in the pressure chamber
40
, via the line
14
and the conduit
54
in the valve body
26
. The second control valve
68
is opened by the control unit
66
, so that high pressure cannot build up in the control pressure chamber
52
, despite its communication
56
with the conduit
54
; instead, this pressure is now reduced to that of the fuel tank
24
. By means of the throttle restrictions
58
and
71
, it is attained that only a slight fuel quantity can flow out of the conduit
54
into the fuel tank
24
. Once the pressure prevailing in the pressure chamber
40
has reached a level such that this pressure, via the pressure shoulder
42
, exerts a force operative in the opening direction
29
on the injection valve member
28
that is greater than the force of the closing spring
44
, the injection valve member
28
lifts with its sealing face
34
away from the valve seat
36
, and fuel is injected through the injection openings
32
into the combustion chamber of the cylinder of the engine. The opening pressure of the fuel injection valve
12
is then dependent only on the force of the closing spring
44
, because of the opened second control valve
68
. The course of pressure during the injection is determined by the profile of the cam
20
.
Alternatively, it can also be provided that during the preinjection the first control valve
60
is opened, so that the communication
59
with the pressure reservoir
62
is opened. In that case, the pressure level at which the preinjection takes place is determined by the pressure set by means of the pressure limiting valve
64
in the pressure reservoir
62
. The opening pressure of the fuel injection valve
12
is lower than the pressure set in the pressure reservoir
62
by the pressure limiting valve
64
. In
FIG. 3
, the course of the pressure P at the injection openings
32
of the fuel injection valve
12
is shown over the time t during one injection cycle. The preinjection corresponds to the injection phase marked I in FIG.
3
.
To terminate the preinjection, the second control valve
68
is closed by the control unit
66
, so that the control pressure chamber
52
is disconnected from the fuel tank
24
, and pressure builds up in the control pressure chamber
52
via its communication
56
with the conduit
54
. As a result, via the piston
50
, a force that reinforces the force of the closing spring
44
is generated on the injection valve member
28
, so that the injection valve member
28
moves counter to its opening direction
29
and comes to rest with its sealing face
34
on the valve seat
36
, terminating the injection.
For an ensuing main injection, the second control valve
68
is opened by the control unit
66
, so that the control pressure chamber
52
is relieved again, and the fuel injection valve
12
opens. The first control valve
60
can be closed at the onset of the main injection, so that the communication
59
with the pressure reservoir
62
is interrupted, and a pressure buildup takes place in the line
14
and the pressure chamber
40
of the fuel injection valve
12
, in accordance with the profile of the cam
20
. Alternatively, it may also be provided that the first control valve
60
initially still remains open, so that because of the open communication
59
with the pressure reservoir
62
, only a pressure corresponding to the pressure set by the pressure limiting valve
64
in the pressure reservoir
62
can build up in the line
14
and in the pressure chamber
40
of the fuel injection valve
12
. The main injection then begins at a pressure level at which the preinjection has also occurred. With the first control valve
60
closed, the main injection begins at a higher pressure level than when the first control valve
60
is initially open. Next, the first control valve
60
is closed by the control unit
66
, and the main injection takes place at a pressure generated in the pump work chamber
22
in accordance with the profile of the cam
20
. It can also be provided that the first control valve
60
is initially closed while the second control valve
68
still remains closed, so no injection takes place yet. Then the second control valve
68
is opened only in delayed fashion, thereby delaying the onset of the main injection, and furthermore the main injection begins at a higher pressure. The main injection corresponds to an injection phase marked II in
FIG. 3
; the pressure course is shown in a solid line for the case where the first control valve
60
is open at the onset, and the pressure course is shown in a dashed line for the case where the first control valve
60
is already closed at the onset.
To terminate the main injection, the second control valve
68
is closed by the control unit
66
, so that the control pressure chamber
52
is disconnected from the fuel tank
24
, and in the control pressure chamber
52
, because of its communication with the conduit
54
and thus with the pump work chamber
22
, high pressure builds up, by which the fuel injection valve
12
is closed. The first control valve
60
remains closed here, so that the communication
59
with the pressure reservoir
62
is interrupted. For a postinjection, the second control valve
68
is re-opened by the control unit
66
, so that the control pressure chamber
52
is relieved again and the fuel injection valve
12
opens. The postinjection takes place with a pressure course corresponding to the profile of the cam
20
. Alternatively, it can be provided that for the postinjection the first control valve
60
is opened, so that the postinjection takes place only at the pressure level corresponding to the pressure reservoir
62
. To terminate the postinjection, the second control valve
68
is closed by the control unit
66
, and/or the first control valve
60
is opened by the control unit
66
. The postinjection corresponds to an injection phase marked III in FIG.
3
.
After the termination of the postinjection, the second control valve
68
can be closed or opened. The first control valve
60
is opened, so that the communication
59
with the pressure reservoir
62
is opened. In the pump work chamber
22
, the pressure drops down to the pressure in the fuel tank
24
, or to the pressure generated by the feed pump
21
. The pump work chamber
22
is disconnected from the line
14
by the check valve
25
, and in the line
14
, conduit
54
and pressure chamber
40
of the fuel injection valve
12
, a pressure is established in accordance with the pressure determined by the pressure limiting valve
64
in the pressure reservoir
62
.
In
FIG. 2
, the fuel injection apparatus is shown in a second exemplary embodiment, in which the basic layout is the same as in the first exemplary embodiment described above, but the control of the pressure in the pressure reservoir
62
is modified. For controlling the pressure in the pressure reservoir
62
, a third control valve
74
is provided instead of the pressure limiting valve
64
. The third control valve
74
is electrically triggerable and has an actuator
75
, which may be an electromagnet or a piezoelectric actuator and is electrically triggered and by which a valve member of the control valve
74
is movable. The third control valve
74
is embodied as a 2/2-way valve, and by it in a first switching position a communication
76
of the pressure reservoir
62
with the fuel tank
24
, as a relief chamber, is opened, and in a second switching position the communication
76
with the fuel tank
24
is interrupted. The third control valve
74
is likewise triggered by the control unit
66
. In addition, a pressure sensor
78
is provided, by which the pressure in the pressure reservoir
62
is detected and which communicates with the control unit
66
. By suitable triggering of the third
74
by the control unit
66
, the pressure in the pressure reservoir
62
can be variably adjusted. For instance, for the preinjection phase I and the onset of the main injection phase II, the pressure in the pressure reservoir
62
can be increased and variably adjusted as a function of engine operating parameters, so that correspondingly the pressure at which the preinjection takes place and the main injection begins is variable. The standing pressure in the line
14
and the pressure chamber
40
of the fuel injection valve
12
when the pump work chamber
22
is relieved can also be variably adjusted. Otherwise, the mode of operation of the fuel injection apparatus of the second exemplary embodiment is the same as in the first exemplary embodiment.
In
FIG. 4
, a further version of the fuel injection apparatus is shown, in which the basic layout is essentially the same as in the first or second exemplary embodiment, but the disposition and embodiment of the second control valve
168
is modified. The second control valve
168
is electrically triggerable and has an actuator
169
, which can be an electromagnet or a piezoelectric actuator, is electrically triggered, and by which a valve member of the control valve
168
is movable. The second control valve
168
is disposed in the communication
56
of the control pressure chamber
52
with the conduit
54
. The second control valve
168
is embodied as a 3/2-way valve, by which in a first switching position the communication
56
of the control pressure chamber
52
with the conduit
54
and thus with the pump work chamber
22
is opened, and the control pressure chamber
52
is disconnected from the fuel tank
24
, as a relief chamber. In a second switching position of the second control valve
168
, the control pressure chamber
52
communicates with the fuel tank
24
as a relief chamber, and the communication
56
with the conduit
54
and thus with the pump work chamber
22
is interrupted. To enable the opening of the fuel injection valve
12
, the second control valve
168
is moved by the control unit
66
into its second switching position, in which the control pressure chamber
52
is relieved into the fuel tank
24
, and for closure of the fuel injection valve
12
, the second control valve
168
is moved into its first switching position, in which the control pressure chamber
52
communicates with the conduit
54
. Otherwise, the mode of operation of the fuel injection apparatus in this modified version is the same as in the first or second exemplary embodiment.
In
FIG. 5
, a further version of the fuel injection apparatus is shown, in which the basic layout is essentially the same as in the first or second exemplary embodiment, but the disposition and embodiment of the second control valve
268
is modified. The second control valve
268
is electrically triggerable and has an actuator
269
, which can be an electromagnet or a piezoelectric actuator, is electrically triggered, and by which a valve member of the control valve
268
is movable. The line
14
is connected to the second control valve
268
on one side, and on the other, the conduit
54
to the pressure chamber
40
and the communication
56
to the control pressure chamber
52
are connected to it. The second control valve
268
is embodied as a 3/2-way valve, by which in a first switching position the communication
56
of the control pressure chamber
52
with the conduit
54
is opened, and the conduit
54
is disconnected from the line
14
and thus from the pump work chamber
22
. In a second switching position of the second control valve
268
, the control pressure chamber
52
is disconnected from the conduit
54
by this control valve, and the conduit
54
communicates with the line
14
and thus with the pump work chamber
22
. The control pressure chamber
52
has a communication
270
with the fuel tank
24
, as a relief chamber, in which a check valve
272
that opens toward the fuel tank
24
is disposed, and a throttle restriction (not shown) can also be provided. To enable the opening of the fuel injection valve
12
, the second control valve
268
is put in its second switching position by the control unit
66
, in which position the control pressure chamber
52
is disconnected from the conduit
54
and the conduit
54
communicates with the line
14
, so that the pressure generated by the fuel pump
10
reaches the pressure chamber
40
of the fuel injection valve
12
, and the control pressure chamber
52
is relieved into the fuel tank
24
. To close the fuel injection valve
12
, the second control valve
268
is put in its first switching position, in which the control pressure chamber
52
communicates with the conduit
54
, but the conduit
54
is disconnected from the line
14
. The pressure prevailing in the pressure chamber
40
of the fuel injection valve
12
is then operative in the control pressure chamber
52
as well, as a result of which the fuel injection valve
12
is closed. Otherwise, the mode of operation of the fuel injection apparatus in this modified version is the same as in the first or second exemplary embodiment.
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.
Claims
- 1. A fuel injection apparatus for internal combustion engines, the apparatus comprisingone fuel pump (10) for each cylinder of the engine, which pump has a pump piston (18), driven by the engine in a reciprocating motion, that defines a pump work chamber (22) to which fuel is delivered from a fuel tank (24) and which communicates with a fuel injection valve (12) that has an injection valve member (28) by which at least one injection opening (32) is controlled and which is movable in an opening direction (29) counter to a closing force by the pressure generated in the pump work chamber (22), a first electrically controlled control valve (60), by which a communication (59) of the pump work chamber (22) with a diversion chamber (62) is controlled, and a second electrically controlled control valve (68; 168; 268), by which the pressure prevailing in a control pressure chamber (52) of the fuel injection valve (12) is controlled, by which the injection valve member (28) is urged at least indirectly in the closing direction, the diversion chamber (62) being a pressure reservoir, in which an elevated pressure, compared to the pressure prevailing in the fuel tank (24), is maintained.
- 2. The fuel injection apparatus according to claim 1, further comprising a pressure limiting valve (64) that opens toward the fuel tank (24) to maintain the pressure in the pressure reservoir (62) at least nearly constant.
- 3. The fuel injection apparatus according to claim 1, further comprising a third electrically controlled valve (74) operable to variably adjust the pressure in the pressure reservoir (62).
- 4. The fuel injection apparatus according to claim 3, wherein the pressure in the pressure reservoir (62) is detected by a sensor device (78), which communicates with an electric control unit (66) by which the third control valve (74) is triggered in order to adjust a predetermined pressure in the pressure reservoir (62).
- 5. The fuel injection apparatus according to claim 3 wherein a communication (76) of the pressure reservoir (62) with a relief chamber (24) is controlled by the third control valve (74).
- 6. The fuel injection apparatus according to claim 4 wherein a communication (76) of the pressure reservoir (62) with a relief chamber (24) is controlled by the third control valve (74).
- 7. The fuel injection apparatus according to claim 1 further comprising a check valve (23) that opens toward the pump work chamber (22) disposed in the communication of the pump work chamber (22) with the fuel tank, through which fuel is delivered to the pump work chamber (22).
- 8. The fuel injection apparatus according to claim 2 further comprising a check valve (23) that opens toward the pump work chamber (22) disposed in the communication of the pump work chamber (22) with the fuel tank, through which fuel is delivered to the pump work chamber (22).
- 9. The fuel injection apparatus according to claim 3 further comprising a check valve (23) that opens toward the pump work chamber (22) disposed in the communication of the pump work chamber (22) with the fuel tank, through which fuel is delivered to the pump work chamber (22).
- 10. The fuel injection apparatus according to claim 4 further comprising a check valve (23) that opens toward the pump work chamber (22) disposed in the communication of the pump work chamber (22) with the fuel tank, through which fuel is delivered to the pump work chamber (22).
- 11. The fuel injection apparatus according to claim 1 further comprising a check valve (25) that opens toward the first control valve (60) disposed in the communication of the pump work chamber (22) with the first control valve (60).
- 12. The fuel injection apparatus according to claim 2 further comprising a check valve (25) that opens toward the first control valve (60) disposed in the communication of the pump work chamber (22) with the first control valve (60).
- 13. The fuel injection apparatus according to claim 3 further comprising a check valve (25) that opens toward the first control valve (60) disposed in the communication of the pump work chamber (22) with the first control valve (60).
- 14. The fuel injection apparatus according to claim 7 further comprising a check valve (25) that opens toward the first control valve (60) disposed in the communication of the pump work chamber (22) with the first control valve (60).
- 15. The fuel injection apparatus according to claim 1 wherein the second control valve (168) is embodied as a 3/2-way valve, by which, in a first switching position, the control pressure chamber (52) communicates with the pump work chamber (22) and is disconnected from a relief chamber (24), and by which in a second switching position the control pressure chamber (52) communicates with the relief chamber (24) and is disconnected from the pump work chamber (22).
- 16. The fuel injection apparatus according to claim 7 wherein the second control valve (168) is embodied as a 3/2-way valve, by which, in a first switching position, the control pressure chamber (52) communicates with the pump work chamber (22) and is disconnected from a relief chamber (24), and by which in a second switching position the control pressure chamber (52) communicates with the relief chamber (24) and is disconnected from the pump work chamber (22).
- 17. The fuel injection apparatus according to claim 1 wherein the second control valve (268) is embodied as a 3/2-way valve, by which in a first switching position the control pressure chamber (52) is disconnected from a pressure chamber (40) of the fuel injection valve (12) and the pressure chamber (40) communicates with the pump work chamber (22), and by which in a second switching position the control pressure chamber (52) communicates with the pressure chamber (40) and the pressure chamber (40) is disconnected from the pump work chamber (22).
- 18. The fuel injection apparatus according to claim 2 wherein the second control valve (268) is embodied as a 3/2-way valve, by which in a first switching position the control pressure chamber (52) is disconnected from a pressure chamber (40) of the fuel injection valve (12) and the pressure chamber (40) communicates with the pump work chamber (22), and by which in a second switching position the control pressure chamber (52) communicates with the pressure chamber (40) and the pressure chamber (40) is disconnected from the pump work chamber (22).
- 19. The fuel injection apparatus according to claim 7 wherein the second control valve (268) is embodied as a 3/2-way valve, by which in a first switching position the control pressure chamber (52) is disconnected from a pressure chamber (40) of the fuel injection valve (12) and the pressure chamber (40) communicates with the pump work chamber (22), and by which in a second switching position the control pressure chamber (52) communicates with the pressure chamber (40) and the pressure chamber (40) is disconnected from the pump work chamber (22).
- 20. The fuel injection apparatus according to claim 17 wherein the control pressure chamber (52) has a communication (270) with a relief chamber (24), in which a check valve (272) opening toward the relief chamber (24) is preferably disposed.
Priority Claims (1)
Number |
Date |
Country |
Kind |
101 12 432 |
Mar 2001 |
DE |
|
US Referenced Citations (8)