Internal-combustion engines – Spark ignition timing control – Electronic control
Utility Patent
1998-09-28
2001-01-02
Kamen, Noah P. (Department: 3747)
Internal-combustion engines
Spark ignition timing control
Electronic control
C123S406350
Utility Patent
active
06167868
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to a method for determining ignition angles for individual cylinders in a multicylinder internal combustion engine, in particular as a function of its knocking behavior. Ignition angles are also referred to as shift values or displacement values. With respect to ignition angles for cylinders, “early direction” means in the direction of early ignition and “late direction” means in the direction of late ignition. Shift values (ZW
1
[KF
1
(z)]) for families of characteristics (KF
1
(z)), i.e., the characteristic map, for individual cylinders are adjusted in a first adaptation loop, in a “late” direction when engine knocking occurs and in an “early” direction when engine knocking ceases, based on an invariable “global” basic characteristic map or family of characteristics (KF
B
) dependent on load (L) and engine speed (n) and associated with all of the cylinders (z). An adaptation loop is also referred to in the art as a regulating process or a control loop. Global shifting by a global shift value (ZW
2
) in the “late” direction or back in the “early” direction takes place in a second adaptation loop, when a magnitude of the adjusted ignition angle (ZW
1
) (averaged over all of the cylinders) of the first adaptation loop exceeds a predetermined maximum value (ZW
1max
) or is less than a predetermined minimum value (ZW
1min
) at an operating point P(n, L). A third adaptation loop is initiated when the internal combustion engine is stopped. Such a method having a plurality of control loops has been disclosed in U.S. Pat. No. 4,631,680.
The individual control loops—“adaptation loops”—in known knocking control systems operate by using various methods.
For example, if, during engine operation, a knocking event is identified at an operating point P(n, L), which is determined by the load L (=air mass or equivalent variable) and the engine speed n, in a cylinder z in the internal combustion engine, the ignition angle ZW for the relevant cylinder is adjusted, in a first (fast) adaptation loop, in the late direction, independently of the other cylinders, by a specific shift value ZW
1
[KF
1
(z)] which is stored in a shift characteristic map or family of characteristics KF
1
(z) for individual cylinders, independently of the other cylinders, based on a value ZW
B
in the family of characteristics, associated with the operating point P, in a basic family of characteristics KF
B
which is associated with all of the cylinders z and is invariable—“global”. That reduces the probability of knocking combustion occurring in that cylinders. See the FIGURE of the drawing.
In the reference symbols, a subscript digit denotes the number of the adaptation loop and z denotes the cylinder number. Subscript digits or letters without any subsequent bracketed expression (for example ZW
B
, ZW
2
) apply “globally” to all cylinder. See the FIGURE of the drawing. Furthermore, in the following text it is assumed that ignition angle shifts in the late direction are provided with negative mathematical signs, and those in the early direction are provided with positive mathematical signs.
When the engine is being operated without knocking, the shift value ZW
1
[KF
1
(z)] for individual cylinders is adjusted back in the early direction step-by-step (and is stored in the family of characteristics KF
1
(z)), either until knocking starts to occur again or until the shift value ZW
1
[KF
1
(z)]=0 for individual cylinders is reached.
Upon leaving the current operating point P, the instantaneous adjusted ignition angle ZW
1
[KF
1
(z)] is stored in the adaptation family of characteristics KF
1
(z) for individual cylinders, so that when this operating point is reached again at a later point in time, initial ignition angle control values ZW
1
[KF
1
(z)] for individual cylinders are available for knocking control.
If, for example, the magnitude of a mean adjusted ignition angle ZW
1
(=mean value of the adjusted ignition angles for all of the cylinders at a specific operating point P) exceeds a predetermined maximum value ZW
1max
then a global shift in the late direction is carried out by a predetermined, global shift value ZW
2
with respect to the global basic family of characteristics KF
B
.
In this way, information that has been learned at an operating point P can also be made usable for operating points that have not yet been passed through and for the other cylinders. Such a situation can occur, for example, after the vehicle has been refueled with fuel of a lower octane rating.
If, during subsequent operation without knocking, the magnitude of the mean adjusted ignition angle ZW
1
becomes less than a predetermined minimum value ZW
1min
then the global shift value ZW
2
is slowly reduced again to the value “0”. This part of the method is called the “second (slow) adaptation loop”.
The current ignition angle ZW(z) of a cylinder z during engine operation is accordingly made up as follows when an operating point change takes place:
ZW
(
z
)=
ZW
B
+ZW
1
[KF
1
(
z
)]+
ZW
2
;
that is to say, for example, for cylinder
1
:
ZW
(1)=
ZW
B
+ZW
1
[KF
1
(1)]+
ZW
2
.
In the case of the subject matter of U.S. Pat. No. 4,631,680, the ignition angle values which are worked out—“learned”—during engine operation are stored in a non-volatile manner when the internal combustion engine is stopped in order to ensure that initial ignition time control values are immediately available again, once the engine has been started again. This involves a considerable memory requirement.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a method for determining ignition angles for individual cylinders in a multicylinder internal combustion engine, which overcomes the hereinafore-mentioned disadvantages of the heretofore-known methods of this general type and which processes those data which have been determined in a first and a second adaptation loop during engine operation before storing them, when the internal combustion engine is stopped, in such a way that optimum initial ignition angle control values are available when the engine is next started and as little non-volatile memory as possible is required for storage.
REFERENCES:
patent: 4268910 (1981-05-01), Omori et al.
patent: 4413599 (1983-11-01), Shigematsu et al.
patent: 4428344 (1984-01-01), Focht
patent: 4472776 (1984-09-01), Deleris et al.
patent: 4631680 (1986-12-01), Korb et al.
patent: 4811714 (1989-03-01), Akasu
patent: 4960094 (1990-10-01), Koike et al.
patent: 5003951 (1991-04-01), Komurasaki et al.
patent: 5421304 (1995-06-01), Gibtner et al.
patent: 5657230 (1997-08-01), Hess et al.
Kleczka Wilfried
Krebs Stefan
Gimie Mahmoud M
Greenberg Laurence A.
Kamen Noah P.
Lerner Herbert L.
Siemens Aktiengesellschaft
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