Internal-combustion engines – Combustion chamber means having fuel injection only – Having a particular relationship between injection and...
Reexamination Certificate
2000-10-02
2001-10-16
Dolinar, Andrew M. (Department: 3747)
Internal-combustion engines
Combustion chamber means having fuel injection only
Having a particular relationship between injection and...
C123S436000
Reexamination Certificate
active
06302083
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to a method for cylinder equalization in an internal combustion engine operating by direct injection.
In the case of multi-cylinder, direct-injection internal combustion engines, different interfering influences cause high variances in the mass rate of flow occur between individual injection nozzles despite identical driving. The different fuel quantities lead to different torque contributions of the individual cylinders. And, in addition to aggravating the lack of smooth running through speed fluctuations in the crankshaft, emissions increase.
U.S. Pat. No. 5,385,129 (See DE 41 22 139 A1) discloses a method for cylinder equalization with reference to the fuel injection quantities in the case of an internal combustion engine, in the case of which the angular acceleration of each individual cylinder is detected. The individual measured values of the angular acceleration are intercompared, and in the case of deviations between the individual measured values the fuel injection quantities of the individual cylinders are varied such that deviations are finally avoided and cyclic irregularities in the internal combustion engine are thereby eliminated.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a method for cylinder equalization in an internal combustion engine operating by direct injection that overcomes the before-mentioned disadvantages of the heretofore-known devices of this general type and that specifies a method to compensate simply and rapidly the systematic error in the individual injection nozzles of the injection system both in the case of stationary and in the case of nonstationary operation of the internal combustion engine.
With the foregoing and other objects in view, there is provided, in accordance with the invention, a method for cylinder equalization having the following steps. Providing an internal combustion engine having a crank shaft and cylinders operating by direct injection, each cylinder having a fuel injection quantity. Detecting a speed value of the crankshaft in a quasi-stationary and in a dynamic operating state of the internal combustion engine. Correcting the speed values with a mean-value filter having an envelope delay of zero to form a corrected speed value. Calculating a change in the kinetic energy of the crankshaft in an expansion interval of a cylinder from the corrected speed value. Deriving from the change in kinetic energy of the crankshaft a relative measure for each cylinder that contains information on too much or too little injected fuel quantity. Calculating correction terms for the injection time from this measure. And, changing each cylinder-specific injection time by applying a respective cylinder-specific correction term so that the internal combustion engine runs more smoothly.
In accordance with another feature of the invention, the correction of the speed values is performed according to the following relationship:
n
^
OT
(
i
+
1
)
=
n
OT
(
i
+
1
)
-
n
_
OT
(
i
+
1
)
-
n
_
OT
(
i
)
2
n
^
OT
(
i
)
=
n
OT
(
i
)
-
n
_
OT
(
i
+
1
)
-
n
_
OT
(
i
)
2
where
{circumflex over (n)}
OT(i)
, {circumflex over (n)}
OT(i+1)
is the corrected speed of the cylinder i and i+1, respectively, over a working cycle, and
{overscore (n)}
OT(i)
, {overscore (n)}
OT(i+1)
is the mean value of the speed of the cylinder i and i+1, respectively, over a working cycle.
In accordance with another feature of the invention, the internal combustion engine is a 4-cylinder internal combustion engine and the mean value of the cylinder is calculated as:
{overscore (n)}
OT(i)
=⅛
n
OT(i−2)
+¼
n
OT(i−1)
+¼
n
OT(i)
+¼
n
OT(i+1)
+⅛
n
OT(i+2)
In accordance with another feature of the invention, the internal combustion engine is a 4-cylinder internal combustion engine and the mean value of the cylinder is calculated as:
{overscore (n)}
OT(i+1)
=⅛
n
OT(i−1)
+¼
n
OT(1)
+¼
n
OT(i+1)
+¼
n
OT(i+2)
+⅛
n
OT(i+3)
In accordance with another feature of the invention, the change in the kinetic energy are referred to a value which specifies a maximum fuel energy which can be fed in an interval, and the relative measure is calculated therefrom.
In accordance with another feature of the invention, the change in the kinetic energy is calculated in accordance with the following equation
&Dgr;
E
kin
(
i
)=½·&thgr;·(
{circumflex over (n)}
OT(i+1)
2
−{circumflex over (n)}
OT(i)
2
)
and the measure is determined therefrom as
R
Z(i)
=K
norm
·(
{circumflex over (n)}
OT(k,i+1)
2
−{circumflex over (n)}
OT(k,i)
2
)
where
&THgr; is the mean moment of inertia of the crankshaft,
H
u
is the lower calorific value for the fuel used,
m
Bmax
is the maximum injectable fuel quantity,
{circumflex over (n)}
OT(i)
is the corrected speed at the top dead center of the cylinder i,
{circumflex over (n)}
OT(i+1)
is the corrected speed at the top dead center of the cylinder i+1, and
K
norm
is a normalizing factor which has the value of
Θ
2
·
1
H
u
m
B
max
(
2
π
60
)
2
.
In accordance with another feature of the invention, the correction terms by which the values for the injection times are multiplied are calculated from the calculated measures.
In accordance with another feature of the invention, the correction terms are calculated as
[
δ
Z
(
1
)
,
k
δ
Z
(
2
)
,
k
δ
Z
(
3
)
,
k
δ
Z
(
4
)
,
k
]
=
[
δ
Z
(
1
)
,
k
-
1
δ
Z
(
2
)
,
k
-
1
δ
Z
(
3
)
,
k
-
1
δ
Z
(
4
)
,
k
-
1
]
+
α
·
[
-
(
R
Z
(
1
)
,
k
R
Z
(
2
)
,
k
R
Z
(
3
)
,
k
R
Z
(
4
)
,
k
)
+
1
3
·
(
R
Z
(
2
)
,
k
+
R
Z
(
3
)
,
k
+
R
Z
(
4
)
,
k
R
Z
(
3
)
,
k
+
R
Z
(
4
)
,
k
+
R
Z
(
1
)
,
k
R
Z
(
4
)
,
k
+
R
Z
(
1
)
,
k
+
R
Z
(
2
)
,
k
R
Z
(
1
)
,
k
+
R
Z
(
2
)
,
k
+
RZ
(
3
)
,
k
)
]
with
[
δ
Z
(
1
)
,
0
δ
Z
(
2
)
,
0
δ
Z
(
3
)
,
0
δ
Z
(
4
)
,
0
]
=
[
1
1
1
1
]
as an initialization value, and where
&dgr;
Z(i),k
is the correction term for cylinder i after adaptation step k,
R
Z(i),k
is the residue of the cylinder i relative to the adaptation step k, and
&agr; is a positive, freely selectable adaptation parameter between 0 and 1 which fixes the rate of the adaptation.
The energy released by the combustion in the individual cylinders is converted into kinetic energy of the crankshaft. Cylinder-specific combustion differences are therefore seen in speed fluctuations from which an error can be determined. This cylinder-specific error signal is characteristic of the systematic error in the injection operation in the cylinder. The method excludes faulty adaptations even during non-stationary operation of the internal combustion engine. For example, in the case of acceleration, the characteristic values (i.e., the speed values detected by the speed sensor) are dynamically corrected using an acausal filter. This dynamic correction can determine an error even in the case of speed transitions, and adapt in the overall region of the characteristic diagram. The method uses the crankshaft speed fed to the control device of the internal combustion engine as input variable. In any case, the crankshaft speed is fed to the control device of the internal combustion engine for other control and regulation purposes. Consequently, no additional hardware components are required to enhance the smooth running of the internal combustion engine. This makes the method very cost effective.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a method for cylinder
Kärcher Andreas
Przymusinski Achim
Schernewski Ralf
Dolinar Andrew M.
Greenberg Laurence A.
Lerner Herbert L.
Siemens Aktiengesellschaft
Stemer Werner H.
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