U.S. patent application number 15/699135 was filed with the patent office on 2019-03-14 for method and system for controlling an internal combustion engine.
The applicant listed for this patent is GM GLOBAL TECHNOLOGY OPERATIONS LLC. Invention is credited to Jun-mo Kang, Hejie Lin, Jeffrey A. Morgan.
Application Number | 20190078521 15/699135 |
Document ID | / |
Family ID | 65410610 |
Filed Date | 2019-03-14 |
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United States Patent
Application |
20190078521 |
Kind Code |
A1 |
Kang; Jun-mo ; et
al. |
March 14, 2019 |
METHOD AND SYSTEM FOR CONTROLLING AN INTERNAL COMBUSTION ENGINE
Abstract
A method for controlling an internal combustion engine that
includes sensing a characteristic of combustion in a cylinder of
the engine, generating a combustion characteristic signal from the
sensed characteristic, performing a principal component analysis on
the combustion characteristic signal and a predetermined combustion
characteristic trace to determine first mode coefficients for the
combustion characteristic signal and the predetermined combustion
characteristic trace, determining a difference between the first
mode coefficient of the combustion characteristic signal and the
first mode coefficient of the predetermined combustion
characteristic trace, and controlling the internal combustion
engine based upon the difference.
Inventors: |
Kang; Jun-mo; (An Arbor,
MI) ; Lin; Hejie; (Troy, MI) ; Morgan; Jeffrey
A.; (Macomb, MI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
GM GLOBAL TECHNOLOGY OPERATIONS LLC |
DETROIT |
MI |
US |
|
|
Family ID: |
65410610 |
Appl. No.: |
15/699135 |
Filed: |
September 8, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F02P 5/153 20130101;
F02D 41/0085 20130101; G01M 15/042 20130101; G01M 15/08 20130101;
F02D 35/028 20130101; F02D 35/023 20130101; F02D 41/401
20130101 |
International
Class: |
F02D 35/02 20060101
F02D035/02; F02D 41/00 20060101 F02D041/00; F02D 41/40 20060101
F02D041/40; F02P 5/153 20060101 F02P005/153; G01M 15/08 20060101
G01M015/08; G01M 15/04 20060101 G01M015/04 |
Claims
1. A method for controlling an internal combustion engine, the
method comprising: sensing a characteristic of combustion in a
cylinder of the engine; generating a combustion characteristic
signal from the sensed characteristic; performing a principal
component analysis on the combustion characteristic signal and a
predetermined combustion characteristic trace to determine first
mode coefficients for the combustion characteristic signal and the
predetermined combustion characteristic trace; determining a
difference between the first mode coefficient of the combustion
characteristic signal and the first mode coefficient of the
predetermined combustion characteristic trace; and controlling the
internal combustion engine based upon the difference.
2. The method of claim 1, wherein the combustion characteristic
signal comprises a cylinder pressure signal from a pressure sensor
of the cylinder.
3. The method of claim 1, wherein the predetermined combustion
characteristic trace comprises a predetermined cylinder pressure
trace.
4. The method of claim 1, wherein the combustion characteristic
signal comprises a gap resistance signal from a spark plug of the
cylinder.
5. The method of claim 1, wherein the predetermined combustion
characteristic trace comprises a predetermined gap resistance
trace.
6. The method of claim 1, wherein the predetermined combustion
characteristic trace corresponds to a predetermined CA50 for the
cylinder.
7. The method of claim 1, wherein controlling the internal
combustion engine comprises adjusting a spark timing signal based
upon the difference.
8. The method of claim 1, wherein controlling the internal
combustion engine comprises adjusting a fuel injection timing
signal based upon the difference.
9. A method for balancing multiple cylinders in an internal
combustion engine, the method comprising: sensing a characteristic
of combustion for each cylinder of the engine; generating a
combustion characteristic signal from the sensed characteristic for
each cylinder; performing a principal component analysis on the
combustion characteristic signal of each cylinder and a
predetermined combustion characteristic trace to determine first
mode coefficients for the combustion characteristic signal for each
cylinder and the predetermined combustion characteristic trace;
determining a difference between the first mode coefficient of the
combustion characteristic signal for each cylinder and the first
mode coefficient of the predetermined combustion characteristic
trace; and controlling the combustion in each cylinder based upon
the differences.
10. The method of claim 9, wherein the combustion characteristic
signal for each cylinder comprises a cylinder pressure signal from
a pressure sensor for at least one of the cylinders.
11. The method of claim 9, wherein the predetermined combustion
characteristic trace comprises a predetermined cylinder pressure
trace.
12. The method of claim 9, wherein the combustion characteristic
signal comprises a gap resistance signal from a spark plug of at
least one of the cylinders.
13. The method of claim 9, wherein the predetermined combustion
characteristic trace comprises a predetermined gap resistance
trace.
14. The method of claim 9, wherein the predetermined combustion
characteristic trace corresponds to a predetermined CA50 for at
least one of the cylinders.
15. The method of claim 9, wherein controlling the internal
combustion engine comprises adjusting a spark timing signal based
upon the difference.
16. The method of claim 9, wherein controlling the internal
combustion engine comprises adjusting a fuel injection timing
signal based upon the difference.
17. A control system for an internal combustion engine, the system
comprising: a combustion sensor that samples a combustion
characteristic within a cylinder of an engine in the vehicle
propulsion system and that outputs a combustion characteristic
trace signal; a desired combustion characteristic trace signal
storage that stores a desired combustion characteristic signal; a
controller that is configured to: perform a principal component
analysis to determine first mode coefficients of the combustion
characteristic trace signal and the desired combustion
characteristic signal; compare the first mode components; and
generate a control signal based upon the results of the comparison;
and an engine that is responsive to the control signal.
18. The system of claim 17, wherein the combustion sensor comprises
a pressure sensor that outputs a cylinder pressure signal.
19. The system of claim 17, wherein the control signal comprises a
spark timing signal.
20. The system of claim 17, wherein the control signal comprises a
fuel injection timing signal.
Description
FIELD
[0001] The present disclosure relates to a method and system for
controlling an internal combustion engine.
INTRODUCTION
[0002] This introduction generally presents the context of the
disclosure. Work of the presently named inventors, to the extent it
is described in this introduction, as well as aspects of the
description that may not otherwise qualify as prior art at the time
of filing, are neither expressly nor impliedly admitted as prior
art against this disclosure.
[0003] Combustion phasing, or the time in an engine cycle when
combustion in a cylinder occurs, affects the torque that is
produced from the cylinder. Combustion phasing of a cylinder may be
characterized by a crank angle at which the cylinder burns 50
percent of the fuel in the cylinder, which may be referred to as
crank angle 50 (CA50). Engine controls systems may control the CA50
of a cylinder of an engine such that each cylinder produces its
peak torque, and thereby improve fuel efficiency, economy, and
performance.
[0004] Further, controlling each cylinder in a manner such that
combustion achieves an optimum CA50 may improve engine balancing.
Engine control systems may balance the engine by adjusting the
spark timing of the cylinders to minimize a difference of CA50
between cylinders in the engine. Engine control systems may
estimate the CA50 of a cylinder by measuring the pressure in the
cylinder during an engine cycle and determining the total amount of
heat released due to combustion in the cylinder during the engine
cycle based on the measured cylinder pressure. The CA50 of a
cylinder may be approximately equal to a crank angle at which 50
percent of the total amount of heat is released. Thus, engine
control systems may determine the crank angle at which 50 percent
of the total amount of heat is released based on the total amount
of heat released and a rate of heat release, and set the CA50 equal
to the determined crank angle.
[0005] Estimating the CA50 of each cylinder of an engine in the
manner described above requires a pressure sensor in each cylinder
and involves a large computational burden, which can lead to a poor
response time when controlling the CA50 of each cylinder. This poor
response time decreases the effectiveness of the CA50 control,
which can lead to decrease fuel efficiency, reduced performance,
and degrade vehicle durability and drivability.
[0006] Additionally, to estimate the CA50 of a cylinder the
pressure trace signal must be differentiated. However,
differentiation is highly susceptible to noise. Noise that is
present within the pressure trace signal is amplified when that
signal is differentiated which leads to inaccuracy in CA50
estimation. To minimize or avoid the adverse effects of noise, a
pressure trace signal may need to be filtered to remove or minimize
the noise. This filtering only adds to the computational
burden.
[0007] Calculation of and/or estimation of CA50 is computationally
intensive. The filtering, differentiation, and estimation of each
cylinder requires a high amount of computations which may be
expensive and susceptible to noise error.
SUMMARY
[0008] In an exemplary aspect, a method for controlling an internal
combustion engine that includes sensing a characteristic of
combustion in a cylinder of the engine, generating a combustion
characteristic signal from the sensed characteristic, performing a
principal component analysis on the combustion characteristic
signal and a predetermined combustion characteristic trace to
determine first mode coefficients for the combustion characteristic
signal and the predetermined combustion characteristic trace,
determining a difference between the first mode coefficient of the
combustion characteristic signal and the first mode coefficient of
the predetermined combustion characteristic trace, and controlling
the internal combustion engine based upon the difference.
[0009] In another exemplary aspect, the combustion characteristic
signal is a cylinder pressure signal from a pressure sensor of the
cylinder.
[0010] In another exemplary aspect, the predetermined combustion
characteristic trace is a predetermined cylinder pressure
trace.
[0011] In another exemplary aspect, the combustion characteristic
signal is a gap resistance signal from a spark plug of the
cylinder.
[0012] In another exemplary aspect, the predetermined combustion
characteristic trace is a predetermined gap resistance trace.
[0013] In another exemplary aspect, the predetermined combustion
characteristic trace corresponds to a predetermined CA50 for the
cylinder.
[0014] In another exemplary aspect, controlling the internal
combustion engine is done by adjusting a spark timing signal based
upon the difference.
[0015] In another exemplary aspect, controlling the internal
combustion engine is done by adjusting a fuel injection timing
signal based upon the difference.
[0016] In this manner, fuel economy, efficiency, performance,
drivability, and durability may be improved by controlling
combustion in an internal combustion engine, and providing the
option to balance combustion in multiple cylinders in an engine,
while significantly reducing the computational workload which
results in significant cost savings of the equipment required to
obtain these benefits and while also improving the responsiveness
of the method and systems providing these advantages. Further, in
contrast, with conventional methods and systems direct calculation
of CA50 is completely obviated.
[0017] Further areas of applicability of the present disclosure
will become apparent from the detailed description provided below.
It should be understood that the detailed description and specific
examples are intended for purposes of illustration only and are not
intended to limit the scope of the disclosure.
[0018] The above features and advantages, and other features and
advantages, of the present invention are readily apparent from the
detailed description, including the claims, and exemplary
embodiments when taken in connection with the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] The present disclosure will become more fully understood
from the detailed description and the accompanying drawings,
wherein:
[0020] FIG. 1 is a schematic illustration of principal component
analysis for an internal combustion engine;
[0021] FIG. 2A is a graph illustrating cylinder pressure signals
from each cylinder in a multi-cylinder engine;
[0022] FIG. 2B is a graph illustrating an ensemble average of the
cylinder pressure signals from FIG. 2A;
[0023] FIG. 2C is a graph illustrating the difference between
cylinder pressure signals of each cylinder and the ensemble
average;
[0024] FIG. 2D is a graph illustrating principal components modes
obtained in accordance with an exemplary embodiment of the present
invention;
[0025] FIG. 2E is a graph illustrating the coefficients for the
first five modes for each cylinder;
[0026] FIG. 2F is a graph illustrating the correlation between the
first mode coefficients of each cylinder and the CA50 for each
corresponding cylinder;
[0027] FIG. 3 is a schematic illustration of an engine combustion
control system 300 in accordance with an exemplary embodiment of
the present disclosure;
[0028] FIG. 4A is a graph of CA50 values for each cylinder of a
multi-cylinder engine;
[0029] FIG. 4B is a graph of first mode coefficient values for each
cylinder of a multi-cylinder engine; and
[0030] FIG. 5 illustrates a flowchart 500 of a method in accordance
with an exemplary embodiment of the present disclosure.
DETAILED DESCRIPTION
[0031] The inventors discovered that there is a strong correlation
between the first modal coefficients of a combustion characteristic
signal from engine cylinders in an internal combustion engine and
the CA50 of combustions occurring in those cylinders when
combustions are not balanced. As a result of this discovery, the
inventors have developed a method and system for controlling an
internal combustion engine in which a principal component analysis
may be substituted for a CA50 analysis and obtain similar, if not
identical or better, improvements in fuel economy, fuel efficiency,
and performance. The present disclosure provides these significant
advantages without suffering the downsides of having to perform a
CA50 analysis thereby avoiding the significant, computationally
intensive workload and sensitivity to noise of a CA50 analysis.
Further, the reduction in computational workload of a principal
component analysis provides the additional benefit of improving the
responsiveness over the control of the engine in response to
disturbances which leads to even further improvements in fuel
efficiency, economy, drivability, and performance.
[0032] Co-assigned, and co-pending U.S. patent application Ser. No.
15/252,322, the disclosure of which is incorporate herein in its
entirety, describes a system and method for determining CA50 for a
cylinder and then balancing the cylinders based upon that
determination in a vehicle engine. In that disclosure the
computational workload for CA50 for balancing the engine is reduced
in comparison to convention engine balancing methods and systems.
Rather than computing the CA50 for each and every cylinder in an
engine and then balancing those cylinders, the CA50 for only one of
the cylinders is calculated and the remaining cylinders are
balanced based upon the CA50 calculation from that one cylinder. In
this manner, for example in a four cylinder engine the
computational workload may be reduced by approximately 75%.
However, even though the computational workload may be reduced from
calculating the CA50 from all the cylinders to only one, the
computational workload from calculating that CA50 from that one
cylinder remains significant.
[0033] By way of comparison, the inventors here disclose a method
and system to control combustion in an internal combustion engine
based upon principal component analysis of combustion
characteristic signal that are sensed during operation and then
compare the results to a principal component analysis of
predetermined combustion characteristic signal that may, for
example, correspond to an engine operating at a desired CA50, fuel
efficiency, economy, performance, and/or the like without
limitation.
[0034] The combustion characteristic signal may be a cylinder
pressure trace, an ion sensor trace, spark plug gap resistance
trace (same thing as an ion sensor trace?), or other sensed
combustion characteristic without limitation.
[0035] An exemplary embodiment of the present disclosure performs a
principal component analysis on a combustion characteristic signal
and a predetermined combustion characteristic signal to determine
first modal coefficients. A principal component analysis is a
statistical procedure that uses orthogonal transformation to
convert a set of observations of values into a set of linearly
uncorrelated variables called principal components. Given a set of
observations of possibly correlated signals, the most significant
common mode (first principal mode) and its contribution to the
individual signals (first modal coefficient) can be obtained
through principal component analysis. The exemplary embodiment then
compares the first mode coefficients and controls the engine based
upon the results of that comparison.
[0036] While the principal component analysis decouples the signals
being analyzed into multiple harmonics or component modes, only the
dominant harmonic is significant. Thus, preferably, only the
coefficients for the first component mode or first harmonic are
determined and compared. Controlling the combustion such that the
first mode coefficients match results in the successive harmonics
and corresponding coefficients also matching. This is also
advantageous in that any potential increased sensitivity of the
succeeding/non-primary harmonics to noise has no adverse
effect.
[0037] The predetermined combustion characteristic signal may be
determined by conventional calibration techniques which operate an
engine at a selection of loads and/or speeds to determine a
combustion characteristic signal for each of those selections which
provide a desired and/or optimized fuel efficiency, economy,
performance, CA50, and/or the like without limitation. The
combustion characteristic may correspond to a cylinder pressure
trace, cylinder temperature, cylinder mixture, humidity, and/or the
like without limitation.
[0038] By performing a principal component analysis on a sensed
combustion characteristic signal and a predetermined combustion
characteristic signal, then by controlling combustion such that the
first mode coefficients of these signals match, in essence, the
effect is to control the combustion such that the two signal traces
substantially match in shape. In other words, the control system
and method of the present disclosure adjusts combustion such that
the actual combustion signal matches the shape of the predetermined
combustion characteristic signal.
[0039] In an exemplary embodiment, the method or control system
controls the engine based upon the first mode coefficient
comparison by modifying, for example, the spark timing of each
cylinder, the fuel injection timing, the valve timing, or any other
controllable aspect which may affect combustion without
limitation.
[0040] FIG. 1 schematically illustrates a principal component
analysis for an internal combustion engine having multiple
cylinders. A first graph 100 illustrates individual pressure traces
from four cylinders in an internal combustion engine. In an
exemplary embodiment, these four cylinder pressure traces may be
averaged to arrive at an average cylinder pressure trace 102 as
shown in second graph 104. The differences for each of the
individual pressure traces (from graph 100) from the average
cylinder pressure trace 102 may be determined as represented by
third graph 106. Next a principal component analysis 108 is
performed on each cylinder pressure difference to identify a first
principal mode 110, a second principal mode 112, a third principal
mode 114, and so on. The first mode coefficient 116 for each
cylinder pressure difference may then be identified. The principal
component analysis may also identify additional mode coefficients
118. However, the significance of each succeeding mode coefficient
decreases. Using this type of analysis, exemplary embodiments of
the present disclosure may improve the fuel efficiency, economy,
and performance of an internal combustion engine.
[0041] FIGS. 2A-2F include graphs of signal traces that illustrate
the correlation between CA50 and the coefficient of the first
principle component mode for an engine having four cylinders. Based
upon the relationship demonstrated in these figures, and discovered
by the inventors of the present disclosure, combustion can be
efficiently managed. FIG. 2A illustrates cylinder pressure signal
traces from each of four cylinders in an internal combustion engine
as each corresponding cylinder transitions through crankshaft
angles surrounding top dead center as combustion occurs. These
cylinder pressure signals may be represented as: {p(t,n)}. FIG. 2B
illustrates the ensemble average across all four cylinder pressure
signal traces. The ensemble average may be represented as:
{.mu.(t)}. FIG. 2C illustrates the differences between each
cylinder pressure signal trace (of FIG. 2A) and the ensemble
average across all four cylinder pressure signal traces (of FIG.
2B). The differential pressures in FIG. 2C may be represented as:
{.delta.(t,n)}. The relationship between these traces may be
represented as:
{p(t,n)}={.mu.(t)}+{.delta.(t,n)}
[0042] Where t is time (or degree) and n is the cylinder number.
The differential pressures {.delta.(t,n)} are dependent (i.e.
coupled) because the covariant matrix has non-zero off-diagonal
elements. The covariance matrix may be represented as:
[ .delta. ( t i , n ) .delta. T ( t j , n ) n - 1 ]
##EQU00001##
[0043] The differential pressures {.delta.(t,n)} may be decomposed
into a linear superposition of orthogonal Principal Component Modes
PCMs [.PHI.] as:
{.delta.(t,n)}=[.PHI.(t,m)]{.eta.(m,n)}
[0044] Where m is the mode number. Then the modal coefficient
{.eta.(m,n)} of the PCMs [.PHI.(t,m)] may be determined as:
{.eta.(m,n)}=[.PHI..sup.-1]{.delta.(t,n)}=[.PHI..sup.T]{.delta.(t,n)}
[0045] Where orthogonal PCMs [.PHI.(t,m)] are the eigenvectors of
covariance matrix of differential pressure [.delta.(t,n)]:
[ .delta. ( t i , n ) .delta. T ( t j , n ) n - 1 ] [ .phi. ] = [
.phi. ] [ .lamda. ( m ) ] ##EQU00002##
[0046] Where [.lamda.(m)] is a diagonal matrix of Eigenvalues.
[0047] FIG. 2D illustrates a graph of the principal component modes
obtained in accordance with the present disclosure. FIG. 2E
illustrates a graph of the coefficients of the first five modes
from the principal component analysis. The modes coefficients
changing from the first mode on the left side of the graph to
successive modes as we move to the right in the graph. Clearly, the
first mode coefficients are larger and, thus, more significant than
the succeeding modes. FIG. 2F is a graph illustrating the
correlation between the first mode coefficients from the principal
component analysis from each of the four cylinders and the CA50 for
each cylinder. The horizontal axis of FIG. 2F represents the value
of the first mode coefficient while the vertical axis represents
the crank angle degree for a corresponding CA50. It is easily
observed on FIG. 2F that the first mode coefficient falls along a
line. Therefore, there is a linear relationship between the first
mode coefficient and CA50. This relationship may be represented
by:
Constant = .DELTA. ( CA 50 ) .DELTA. ( PC - First Mode Coefficient
) ##EQU00003##
[0048] Where Constant represents the slope of the line in FIG. 2F,
.DELTA.(CA50) is the change in CA50 and .DELTA.(PC-First Mode
Coefficient) is the change in the first mode coefficient of the
principal component.
[0049] FIG. 3 is a schematic illustration of an engine combustion
control system 300 in accordance with an exemplary embodiment of
the present disclosure. The system 300 starts by sampling
individual cylinder pressure traces at 302 and providing those
samples 304 to a first modal coefficient module 306.
Simultaneously, samples of a desired cylinder pressure trace are
obtained at 308 and those samples 310 are also provided to the
first modal coefficient module 306. The first modal coefficient
module 306 outputs the first modal coefficient for each cylinder at
312 and outputs the first modal coefficient for the desired
cylinder pressure trace at 314. The difference 318 between the
first modal coefficients 312 and 314 is determined at 316. The
difference 318 (or coefficient error) is provided to a balance
control module 320 which determines the relationship between the
difference in first mode coefficient(s) 318 and a spark timing for
each cylinder and outputs a spark timing adjustment signal 322. In
particular, the balance control module determines a spark timing
adjustment signal 322 for each cylinder which will result in the
cylinder pressure traces of each cylinder matching the desired
pressure cylinder trace based on the first modal coefficients,
which also provides the benefit of balancing the cylinders in a
multi-cylinder engine. Simultaneously, a nominal spark timing
signal 324 is generated by a spark timing module 326 based upon
engine operating conditions 328, such as, for example, engine load,
engine speed, and the like without limitation. The spark timing
adjustment signal 322 and the spark timing signal 324 are summed at
330 to provide a spark timing signal 332 for each cylinder in the
engine.
[0050] Further, with the use of the present disclosure, the
sampling rate of the combustion characteristic signal may be
significantly reduced in comparison to conventional methods of
combustion control and/or engine balancing methods and control
systems. Conventional methods and systems may control an aspect of
combustion based upon a signal that is sampled at a high rate for
the purposes of calculating CA50 for each cylinder. For example,
some systems and methods may sample a cylinder pressure signal at
each of 360 degrees within a crankshaft revolution. The bandwidth
and processing power that is required to handle this volume of
sampled data requires a relatively expensive system. In contrast,
the sampling rate that is required by the methods and systems of
the present disclosure is greatly reduced. In an exemplary
embodiment, the methods and systems of the present disclosure may
sample a combustion characteristic signal about three times per
combustion event. The inventors discovered that combustion can be
well controlled with a sampling rate that is as low as only three
samples per combustion event. While the combustion characteristic
signal may be sampled more frequently, only marginal improvements
may be realized from a higher sampling rate.
[0051] The number of samples that are acquired per cycle determine
the number of mode coefficients that are provided by a principal
component analysis. The inventors determined that the preferred
minimum sampling rate may be as low as only three or four samples
per cycle.
[0052] Additionally, the inventors discovered that with the methods
and systems of the present disclosure the computational workload
varies in accordance with the sampling rate and not the number of
cylinders. Therefore, even greater relative improvements in
computational workload is achievable with engines have more
cylinders in comparison to previous methods and systems.
[0053] Referring now to FIGS. 4A and 4B, the effectiveness of an
exemplary embodiment of the present disclosure on a four cylinder
internal combustion engine is clearly illustrated. The horizontal
axes 400 of both graphs of FIGS. 4A and 4B represent the number of
combustion cycles. The vertical axis 402 of FIG. 4A represents the
CA50 and the vertical axis 404 of FIG. 4B represents the values for
the first modal coefficients for each of the four cylinders. The
dashed line in both of FIGS. 4A and 4B represent the desired CA50
(406 in FIG. 4A) and the first modal coefficient of the desired
pressure trace (408 in FIG. 4B). The vertical dashed line 410
extending across both of FIGS. 4A and 4B represents an engine cycle
at which the method and system of the present disclosure is applied
to the engine. Prior to cycle 410, the CA50s (FIG. 4A) for each of
the cylinders clearly vary by a substantial amount and none of
those CA50s align well with the desired CA50 406. After cycle 410,
the methods and systems of the present disclosure clearly cause the
combustion within each to have CA50s which closely follow the
desired CA50 406. This happens as a result of the system and method
controlling the combustion within each cylinder such that the first
mode coefficients for each cylinder closely match the first mode
coefficient of the desired pressure trace 408. Additionally, FIGS.
4A and 4B illustrate the ability for the method and system of the
present disclosure to quickly react and maintain desired combustion
characteristics in response to a step change represented in region
412 of both FIGS.
[0054] FIG. 5 illustrates a flowchart 500 of a method in accordance
with an exemplary embodiment of the present disclosure. The method
starts at step 502 and continues to step 504 where a characteristic
of combustion in a cylinder of an engine is sensed. The method then
continues to step 506 where a predetermined combustion
characteristic trace is selected based on engine operating
condition and the method continues to step 508. In step 508, a
combustion characteristic signal is generated based upon the sensed
characteristic and the method continues to step 510. In step 510,
the method performs a principal component analysis on the
combustion characteristic signal and the predetermined combustion
characteristic trace to determine first mode coefficients for the
combustion characteristic signal and the predetermined combustion
characteristic trace. The method then continues to step 512 where
the method determines a difference between the first mode
coefficient of the combustion characteristic signal and the first
mode coefficient of the predetermined combustion characteristic
trace and the method then continues to step 514. In step 514, the
method controls the internal combustion engine based upon the
difference. The method then ends in step 516.
[0055] This description is merely illustrative in nature and is in
no way intended to limit the disclosure, its application, or uses.
The broad teachings of the disclosure can be implemented in a
variety of forms. Therefore, while this disclosure includes
particular examples, the true scope of the disclosure should not be
so limited since other modifications will become apparent upon a
study of the drawings, the specification, and the following
claims.
* * * * *