U.S. patent application number 11/981928 was filed with the patent office on 2008-07-03 for method for operating an internal combustion engine.
Invention is credited to Andreas Baumann, Frank Ottusch.
Application Number | 20080156300 11/981928 |
Document ID | / |
Family ID | 38135708 |
Filed Date | 2008-07-03 |
United States Patent
Application |
20080156300 |
Kind Code |
A1 |
Baumann; Andreas ; et
al. |
July 3, 2008 |
Method for operating an internal combustion engine
Abstract
An internal combustion engine includes multiple combustion
chambers. The supply of fuel into at least one subset of the
combustion chambers can temporarily be interrupted. It is provided
that the fuel be injected into the combustion chambers directly and
during a switchover phase for interrupting or resuming fuel
injection into the subset of combustion chambers, at least
temporarily via multiple injections.
Inventors: |
Baumann; Andreas;
(Farmington Hills, MI) ; Ottusch; Frank;
(Leonberg, DE) |
Correspondence
Address: |
KENYON & KENYON LLP
ONE BROADWAY
NEW YORK
NY
10004
US
|
Family ID: |
38135708 |
Appl. No.: |
11/981928 |
Filed: |
October 31, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11646922 |
Dec 27, 2006 |
7331332 |
|
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11981928 |
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Current U.S.
Class: |
123/481 ;
123/198F |
Current CPC
Class: |
F02D 41/0087 20130101;
F02D 2250/21 20130101; F02P 5/1504 20130101; F02D 41/402 20130101;
F02D 41/0005 20130101; Y02T 10/44 20130101; F02D 37/02 20130101;
Y02T 10/40 20130101; F02D 17/02 20130101; F02D 41/126 20130101;
F02D 41/0082 20130101; F02D 2250/28 20130101 |
Class at
Publication: |
123/481 ;
123/198.F |
International
Class: |
F02D 7/00 20060101
F02D007/00; F02D 17/02 20060101 F02D017/02; F02D 13/06 20060101
F02D013/06 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 27, 2006 |
DE |
102005062552.5 |
Claims
1. A method for operating an internal combustion engine having
multiple combustion chambers, the method comprising: intermittently
interrupting a supply of fuel into at least one subset of the
combustion chambers; and directly injecting fuel into the
combustion chambers during a switchover phase for one of
interrupting and resuming the fuel injection into at least the
subset of the combustion chambers at least intermittently via
multiple injections, wherein introduction of the fuel into the at
least one subset of the combustion chambers is divided into
multiple individual injection quantities per working cycle.
2. The method according to claim 1, wherein, during multiple
injections, at least one injection takes place during an intake
stroke and another injection takes place during a compression
stroke of the same work cycle.
3. The method according to claim 1, further comprising: prior to a
switchover for an interruption of the fuel injection into at least
the subset of the combustion chambers, increasing an air charge and
retarding an ignition angle; and at a start or during an increase
of the air charge and an adjustment of an ignition angle, making a
switchover from a single injection to multiple injections.
4. The method according to claim 3, further comprising terminating
the multiple injections directly during or after the
switchover.
5. The method according to claim 1, further comprising: during or
directly prior to a switchover for a resumption of the fuel
injection into at least the subset of the combustion chambers,
making a switchover from a single injection to multiple
injections.
6. The method according to claim 5, further comprising: after the
switchover for a resumption of the fuel injection into at least the
subset of the combustion chambers, lowering an air charge and
canceling a retarding of an ignition angle; and making a switchover
from multiple injections to a single injection at least at about an
end of a reduction and a cancellation of the retarding.
7. The method according to claim 1, wherein one of a crankshaft
angle and a point in time of a switchover from a single injection
to multiple injections is at least indirectly a function of an
instantaneous operating state of the internal combustion
engine.
8. The method according to claim 7, wherein the instantaneous
operating state is an instantaneous load.
9. A computer program embodied in a computer-readable medium
containing instructions which when executed by a processor perform
the following method for operating an internal combustion engine
having multiple combustion chambers: intermittently interrupting a
supply of fuel into at least one subset of the combustion chambers;
and directly injecting fuel into the combustion chambers during a
switchover phase for one of interrupting and resuming the fuel
injection into at least the subset of the combustion chambers at
least intermittently via multiple injections, wherein introduction
of the fuel into the at least one subset of the combustion chambers
is divided into multiple individual injection quantities per
working cycle.
10. An electric storage medium for a control/regulating unit of an
internal combustion engine having multiple combustion chambers, the
storage medium storing a computer program containing instructions
which when executed by a processor perform the following method for
operating the engine: intermittently interrupting a supply of fuel
into at least one subset of the combustion chambers; and directly
injecting fuel into the combustion chambers during a switchover
phase for one of interrupting and resuming the fuel injection into
at least the subset of the combustion chambers at least
intermittently via multiple injections, wherein introduction of the
fuel into the at least one subset of the combustion chambers is
divided into multiple individual injection quantities per working
cycle.
11. A control/regulating unit for an internal combustion engine
having multiple combustion chambers, comprising: an arrangement for
intermittently interrupting a supply of fuel into at least one
subset of the combustion chambers; and an arrangement for directly
injecting fuel into the combustion chambers during a switchover
phase for one of interrupting and resuming the fuel injection into
at least the subset of the combustion chambers at least
intermittently via multiple injections, wherein introduction of the
fuel into the at least one subset of the combustion chambers is
divided into multiple individual injection quantities per working
cycle.
Description
BACKGROUND INFORMATION
[0001] The concept known from the market as "half-engine operation"
is used in internal combustion engines having intake manifold
injection. In this concept, the injection of fuel into certain
cylinders in an internal combustion engine is interrupted in
certain operating states for the purpose of reducing the fuel
consumption. For example, in an eight-cylinder engine, half of the
cylinders are shut off in this way. In order to prevent torque
fluctuations or even torque jumps from occurring when the fuel
injection into (and thus the combustion in) a subset of combustion
chambers is interrupted and when injection is resumed, the air
charge in the combustion chambers is increased prior to an
interruption and the ignition angle is retarded in such a way that
the torque remains the same overall.
[0002] If a subset of combustion chambers is shut off by
interrupting the injection, the ignition angle is suddenly advanced
at the time of shut-off. In this way, the combustion chambers into
which fuel continues to be injected are able to immediately
compensate for the dropping power of the shut off combustion
chambers. This would not be possible by simply increasing the air
filling at the time of shut-off due to the inertia of the filling
path. The operation is reversed when injection into the subset of
combustion chambers in question is resumed after a previous
interruption.
[0003] Furthermore, the principle of overrun shut-off is also known
in which not only a subset of the combustion chambers but all
combustion chambers are temporarily shut off in the overrun
mode.
[0004] An object of the present invention is to provide a method
mentioned at the outset in which the operating range of the
internal combustion engine in which the fuel supply to at least one
subset of the combustion chambers may be temporarily interrupted is
extended with low emissions at the same time.
SUMMARY OF THE INVENTION
[0005] It is possible in the case of direct fuel injection to
divide the introduction of fuel into a combustion chamber into
multiple individual injections or injection quantities per
combustion cycle. If this is implemented during a switchover phase
during which injection of fuel into at least one subset of
combustion chambers is interrupted or resumed after an
interruption, the stability of combustion is ensured even if the
ignition angle is retarded to a high degree. The operating range in
which the fuel supply into a subset of the combustion chambers may
be temporarily interrupted is considerably extended. Moreover, the
fuel mass introduced into the combustion chambers, i.e., a wall
film on a cold combustion chamber wall, is reduced by such multiple
injections. This results in an emission reduction during operation
of the internal combustion engine. This is particularly favorable
when all combustion chambers are temporarily shut off within the
scope of an overrun shut-off.
[0006] It should be noted at this point that multiple injections
may include two separate injections, but triple or quadruple
injections are also possible during a combustion cycle when special
injectors are used, e.g., injectors having piezoelectric actuators.
Performing multiple injections only from time to time, namely when
there is a switchover phase for interrupting or resuming the
injection, has in turn the advantage that the injector and the
output stage activating the injector are relieved. It should also
be noted at this point that the achieved advantages are the
greatest when the multiple injections are carried out in all the
combustion chambers present.
[0007] It is particularly advantageous when, during multiple
injections, at least one injection takes place during an intake
stroke and another injection takes place during a compression
stroke of the same combustion cycle, thereby clearly stabilizing
the combustion behavior, and the fuel mass introduced into a wall
film of the combustion chamber is definitely reduced in this
way.
[0008] Furthermore, it is provided that an air charge be increased
prior to the switchover for an interruption of the fuel injection
into a subset of combustion chambers and an ignition angle be
retarded and that a switchover is made from single injection to
multiple injections at the start or during the increase of the air
charge and the adjustment of the ignition angle. According to the
present invention, multiple injections are used only shortly before
the switchover for an interruption of the fuel supply into the
subset of combustion chambers. This makes it possible to avoid
unnecessary multiple injections and the injector and an output
stage activating the injector are prevented from suffering damage.
Moreover, using multiple injections according to the present
invention ensures combustion even when the internal combustion
engine is operated with a retarded ignition angle, which improves
the quality of the switchover processes by reducing combustion
misfires, for example.
[0009] According to a specific refinement, multiple injections are
terminated directly during or after the switchover. Since the
ignition angle, previously retarded is displaced back into the
optimum ignition angle range directly with the switchover, thereby
terminating the switchover, the multiple injection is no longer
needed. Due to its quick termination, overloading of the output
stage and the injector is avoided.
[0010] That refinement of the method according to the present
invention aims at the same objective, in which only at the time of
or immediately prior to switchover for a resumption of fuel
injection into the subset of combustion chambers a switchover is
made from a single injection to multiple injections. In this way
also, an unnecessarily long and, for the quality of the switchover
irrelevant, operation with multiple injections is avoided. The
method also aims at the same objective in which an air charge is
dropped and retarding of the ignition angle is reversed after the
switchover for a resumption of fuel injection into the subset of
combustion chambers and in which a switchover is made from multiple
injections to a single injection at least approximately at the and
of the reduction and cancellation of the "retard" position.
[0011] It is particularly advantageous when a crankshaft angle of
the switchover from a single injection to multiple injections is at
least indirectly the function of an instantaneous operating state
of the internal combustion engine, in particular an instantaneous
load. This allows the emission behavior during switchover and the
quality of the switchover process to be improved and the load on
the injector and the output stage to be reduced at the same
time.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 shows a schematic representation of an internal
combustion engine having a first subset of combustion chambers and
a second subset of combustion chambers.
[0013] FIG. 2 shows a diagram in which an air charge and a phase
with multiple injections are plotted against time for the case of
an interruption of the fuel injection into the first subset of
combustion chambers of FIG. 1.
[0014] FIG. 3 shows a diagram in which an ignition angle is plotted
against time during the shut-off of the first subset of combustion
chambers.
[0015] FIG. 4 shows a diagram in which a torque is plotted against
time for the case in which the first subset of combustion chambers
is shut off.
[0016] FIG. 5 shows a diagram similar to FIG. 2 for the case in
which the fuel injection into the first subset of combustion
chambers is resumed.
[0017] FIG. 6 shows a diagram similar to FIG. 3 for the case in
which the fuel injection into the first subset of combustion
chambers is resumed.
[0018] FIG. 7 shows a diagram similar to FIG. 4 for the case in
which the fuel injection into the first subset of combustion
chambers is resumed.
DETAILED DESCRIPTION
[0019] An internal combustion engine is indicated by reference
numeral 10 in FIG. 1. It is used for driving a motor vehicle (not
shown in FIG. 1). Internal combustion engine 10 includes a
plurality of cylinders having combustion chambers 12, only two of
which are shown in FIG. 1 for the sake of simplicity. Combustion
chambers 12 are composed of a first subset 14 of combustion
chambers 12 and a second subset 16 of combustion chambers 12. Under
the assumption of, for example, a total of eight combustion
chambers 12 or cylinders, first subset 14 could include four
combustion chambers 12 and second subset 16 could also include four
combustion chambers 12.
[0020] Combustion air reaches combustion chambers 12 via intake
valves 18 and 20 and intake manifolds 22 and 24. Throttle valves 26
and 28 are situated in each intake manifold 22 and 24 belonging to
a subset 14 and 16. Fuel reaches combustion chambers 12 directly
via injectors 30 and 32. A fuel pressure accumulator 34 and 36,
referred to as "rail," is assigned to each subset 14 and 16 of
combustion chambers 12, to which respective injectors 30 and 32 are
connected. A fuel/air mixture in combustion chambers 12 is ignited
by appropriate spark plugs 38 and 40 and the hot combustion exhaust
gases are discharged into an exhaust pipe 46 via outlet valves 42
and 44.
[0021] The operation of internal combustion engine 10 is controlled
and/or regulated by a control and regulating unit 48. This unit
receives signals from different sensors, e.g., an accelerator pedal
of a motor vehicle, via which a user is able to express a torque
intent, and temperature, pressure, and other sensors which detect
the instantaneous operating state of internal combustion engine 10.
In order to keep the fuel consumption during operation of internal
combustion engine 10 as low as possible, first subset 14 of
combustion chambers 12 may be shut off, if no overly high
performance is demanded from internal combustion engine 10, by
interrupting the injection of fuel by injector 30. In this case,
the torque of internal combustion engine 10 is generated only by
the remaining second subset 16 of combustion chambers 12 whose
injector 32 continues to inject fuel directly. If a higher
performance is demanded from internal combustion engine 10, then
the fuel injection by injector 30 into combustion chambers 12 of
first subset 14 is resumed. If fuel is injected into all combustion
chambers 12 of first subset 14 and second subset 16, this is
referred to as "full-engine operation"; if, however, the fuel
supply into first subset 14 of combustion chambers 12 is
interrupted, this is referred to as "half-engine operation."
[0022] A method for interrupting and resuming the fuel injection
into first subset 14 of combustion chambers 12 is explained in
detail in the following with reference to FIGS. 2 through 7. The
method is stored in a memory of control and regulating unit 48 in
the form of a computer program.
[0023] The switchover phase, during which the fuel injection into
first subset 14 of combustion chambers 12 is interrupted, can be
subdivided into three sections I, II, and III: all combustion
chambers 12 of internal combustion engine 10 are in operation in
section I. Throttle valves 26 and 28 are set in such a way that an
air charge rl is in the range of optimum air charge rl.sub.1. An
ignition angle ZW (FIG. 3) is in the range of optimum ignition
angle ZW.sub.1. A torque M has a value M1.
[0024] During section I of the switchover phase, the instantaneous
operating situation of internal combustion engine 10 is analyzed
and a decision is made in the present case to interrupt the fuel
injection into first subset 14 of combustion chambers 12 via
injectors 30 at a point in time t2. Well before point in time t2,
second section II of the switchover phase starts at a point in time
t1 in that a setpoint value for an air charge rl is abruptly raised
at point in time t1 (dashed curve in FIG. 2). In addition, starting
at point in time t1, fuel is injected into combustion chambers 12
of first subset 14 and second subset 16 by injectors 30 and 32 via
multiple injections, e.g., a double injection, per work cycle. This
is indicated in FIG. 2 by a time bar having reference numeral 50.
Prior to point in time t1, fuel is injected into combustion chamber
12 of internal combustion engine 10 by a single injection.
[0025] Throttle valves 26 and 28 are opened in a controlled manner
due to the abrupt change in the setpoint value for air charge rl.
However, due to the volume of intake manifold 22, the actual value
of air charge rl (solid curve in FIG. 2) follows the abrupt rise of
the setpoint value only gradually. Corresponding to the gradual
change of the actual value of air charge rl in combustion chambers
12, ignition angle ZW, as is apparent from FIG. 3, is gradually
changed toward "retard" from an optimum value ZW.sub.1 to a value
ZW.sub.2 during section II of the switchover phase in such a way
that torque M, provided by internal combustion engine 10, does not
change and remains essentially constant at a value M1. In this way,
a "torque reserve" is built up during section II of the switchover
phase.
[0026] If fuel injection into first subset 14 of combustion
chambers 12 via injectors 30 is abruptly interrupted at point in
time t2, ignition angle ZW is abruptly advanced from retarded value
ZW.sub.2 reached up to this point to optimum value ZW.sub.1. In
this way, the torque which is generated by the combustion in second
subset 16 of combustion chambers 12 is abruptly increased, thereby
compensating for the torque drop due to the interruption of the
injection into first subset 14 of combustion chambers 12, so that,
at point in time t2 as well, the torque provided by internal
combustion engine 10 remains constant at value M1. The third
section of the switchover phase starts at point in time t2 at which
internal combustion engine 10 is already running in half-engine
operation. Shortly after the start of third section III, at a point
in time t3, double injection 50 is terminated.
[0027] If a switchover is to be made from half-engine operation
back again to full-engine operation, it is executed according to
FIGS. 5 through 7: the corresponding switchover phase, in which a
switchover is made from half-engine operation to full-engine
operation, can also be subdivided into three sections IV, V, and
VI. The decision is made in first section IV that the fuel
injection into first subset 14 of combustion chambers 12 via
injectors 30 is to be resumed at a point in time t5. Depending on
value M1 of torque M, it is established during section IV that,
starting at a point in time t4 which is shortly before point in
time t5, the fuel is to reach combustion chambers 12, initially of
second subset 16, and then also of first subset 14, via injectors
32 (and starting at point in time t5 also via injectors 30) via
multiple injections, e.g., a double injection, per work cycle (time
bar 52 in FIG. 5). Prior to point in time t4, the internal
combustion engine runs in half-engine operation with a single
injection of fuel into second subset 16 of combustion chambers 12
via injectors 32.
[0028] At switchover point in time t5, at which fuel is again
injected into first subset 14 of combustion chambers 12, the
setpoint value for air charge rl is abruptly lowered (dashed curve
in FIG. 5). In addition, ignition angle ZW is abruptly decreased
from optimum value ZW.sub.1, to a value ZW.sub.2 at point in time
t5, thereby compensating for the additional torque which is
generated by the combustion in first subset 14 of combustion
chambers 12 starting at point in time t5.
[0029] Due to the air volume in intake manifolds 22 and 24, the
actual value (solid curve in FIG. 5) responds to the abrupt change
of the setpoint value for air charge rl with a corresponding delay.
As the actual value of air charge rl drops, ignition angle ZW is
gradually advanced to its value ZW.sub.1. Second section V of the
switchover phase, starting at point in time t5, ends at a point in
time t6 at which the actual value of air charge rl reaches the
setpoint value and at which ignition angle ZW reaches optimum
ignition angle ZW, again. Directly after the end of section V,
double injection 52 is terminated at point in time t7.
[0030] At this point it should be noted that double injections 50
and 52 each include an injection during an intake stroke and an
injection during a compression stroke of the same work cycle of
respective combustion chambers 12. This makes it possible to
stabilize the combustion in combustion chambers 12 when ignition
angle ZW is retarded (value ZW.sub.2). At the same time, the fuel
mass in combustion chambers 12 in the form of a wall film is
smaller than in the case of a single injection only during an
intake stroke. This reduces the emissions during operation of
internal combustion engine 10.
* * * * *