Internal-combustion engines – Charge forming device – Exhaust gas used with the combustible mixture
Reexamination Certificate
2002-01-29
2004-03-16
Argenbright, Tony M. (Department: 3747)
Internal-combustion engines
Charge forming device
Exhaust gas used with the combustible mixture
Reexamination Certificate
active
06705301
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to systems for managing charge flow and EGR fraction in an EGR control system for an internal combustion engine, and more specifically to such systems for determining and producing desired charge flow and EGR fraction commands based on current engine operating conditions.
BACKGROUND OF THE INVENTION
Systems for controlling EGR flow and/or turbocharger swallowing capacity are known and have been widely implemented, particularly in the heavy diesel engine industry. An example of one known system
10
for providing such control is shown in FIG.
1
and includes an internal combustion engine
12
having an intake manifold
14
fluidly coupled to a compressor
18
of a turbocharger
25
via intake conduit
16
, wherein the compressor
18
receives fresh air via intake conduit
20
. The turbocharger compressor
18
is mechanically coupled to a turbocharger turbine
24
via drive shaft
22
, wherein turbine
24
is fluidly coupled to an exhaust manifold
28
of engine
12
via exhaust conduit
30
, and is further fluidly coupled to ambient via exhaust conduit
26
. An EGR valve
32
is disposed in fluid communication with the intake conduit
16
and the exhaust conduit
30
, and a differential pressure sensor, or &Dgr;P sensor,
34
is disposed across the EGR valve
32
to sense a pressure change, or delta pressure, across valve
32
. An electronic EGR flow controller
36
has a first input receiving a signal indicative of desired EGR valve position, and has a first output electrically connected to EGR valve
32
via signal path
38
. In the system shown in
FIG. 1
, the EGR flow controller is configured to apply the EGR position signal directly to the EGR valve
32
. Controller
36
includes a second input receiving a signal indicative of a desired delta pressure value, or &Dgr;P target, and a third input electrically connected to the &Dgr;P sensor
34
via signal path
40
and receiving a signal thereat indicative of sensed delta pressure (&Dgr;P). The &Dgr;P value is subtracted from the &Dgr;P target value at summing node
42
, and a &Dgr;P error value produced thereby is applied to a proportional-integral (PI) or other known controller
44
. An output of controller
44
produces a variable geometry turbocharger signal VGT that is used to control the swallowing capacity and/or efficiency of the turbocharger
25
via any of a number of known techniques via signal path
46
. In operation, charge flow to the intake manifold
14
of engine
12
, defined for the purposes of the present invention as the sum of fresh air flow into intake conduit
16
and EGR flow into intake conduit
16
, is controlled via control of the position of the EGR valve
32
and the pressure differential between the exhaust conduit
30
and intake conduit
16
.
One drawback associated with an EGR flow control system
10
of the type illustrated in
FIG. 1
is that there exists an interdependency between charge flow and EGR flow such that EGR flow and fresh air flow cannot be controlled separately. Once EGR flow is established by the EGR flow controller
36
, the resulting charge flow is defined by whatever fresh air flow is available. System
10
may therefore be optimized for NOx control or for particulate control, but generally not for both. It is accordingly desirable to provide for an EGR control system wherein EGR flow and fresh air flow may be controlled separately to therefore gain better and more consistent control over the charge flow. Systems for achieving this goal are described U.S. Pat. No. 6,408,834, entitled SYSTEM FOR DECOUPLING EGR FLOW AND TURBOCHARGER SWALLOWING CAPACITY/EFFICIENCY CONTROL MECHANISMS, and U.S. Pat. No. 6,480,782, entitled SYSTEM FOR MANAGING CHARGE FLOW AND EGR FRACTION IN AN INTERNAL COMBUSTION ENGINE, both of which are assigned to the assignee of the present invention and the disclosures of which are incorporated herein by reference.
In such systems, however, it is further desirable to provide target steady-state charge flow and EGR fraction commands across a wide range of operating conditions in order to optimize engine performance while also constraining engine emissions below specified limits. What is therefore needed is a control strategy operable to provide such target charge flow and EGR fraction commands to manage steady-state engine performance across a wide range of ambient and application conditions, while complying with emissions regulations that vary across those same and other conditions.
SUMMARY OF THE INVENTION
The foregoing shortcomings of the prior art are addressed by the present invention. In accordance with one aspect of the present invention, a system for producing charge flow and EGR fraction commands comprises means for determining a current ambient air density, means for determining a current operating temperature of an internal combustion engine, a memory unit having a number of data sets stored therein, each data set including a subset of charge flow and EGR fraction command values optimized for either of a unique ambient pressure and a unique engine operating temperature, and an engine controller configured to select a first one of said number of said data sets having an associated unique ambient pressure or engine operating temperature that is less than or equal to a corresponding one of said current ambient air density and said current operating temperature, and to select a second one of said number of data sets having an associated unique ambient pressure or engine operating temperature that is greater than or equal to a corresponding one of said current ambient air density and said current operating temperature, said engine controller interpolating between said first and second data sets to produce charge flow value and EGR fraction commands.
One object of the present invention is to provide a system for generating charge flow and EGR fraction commands based on one or more engine operating conditions.
Another object of the present invention is to provide such a system operable to generate such commands based on current ambient air density and/or engine temperature.
These and other objects of the present invention will become more apparent from the following description of the preferred embodiment.
REFERENCES:
patent: 4014302 (1977-03-01), Houston
patent: 4223650 (1980-09-01), Herbert
patent: 4323045 (1982-04-01), Yamashita
patent: 4426848 (1984-01-01), Stachowicz
patent: 4446840 (1984-05-01), Nakagawa et al.
patent: 4452217 (1984-06-01), Kawamura et al.
patent: 4898143 (1990-02-01), Fujimoto et al.
patent: 5150696 (1992-09-01), Kabasin et al.
patent: 5203311 (1993-04-01), Hitomi et al.
patent: 5440880 (1995-08-01), Ceynow et al.
patent: 5456280 (1995-10-01), Palmer
patent: 5490488 (1996-02-01), Aversa et al.
patent: 5546915 (1996-08-01), Isobe
patent: 5601068 (1997-02-01), Nozaki
patent: 5617726 (1997-04-01), Sheridan et al.
patent: 5657630 (1997-08-01), Kjemtrup et al.
patent: 5669365 (1997-09-01), Gartner et al.
patent: 5732688 (1998-03-01), Charlton et al.
patent: 5740786 (1998-04-01), Gartner
patent: 5771868 (1998-06-01), Khair
patent: 5802846 (1998-09-01), Bailey
patent: 5806308 (1998-09-01), Khair et al.
patent: 5931131 (1999-08-01), Hackett
patent: 6480782 (2002-11-01), Brackney et al.
Brackney Larry J.
Brunemann George A.
Charlton Steve
Dollmeyer Thomas A.
Ali Hyder
Argenbright Tony M.
Barnes & Thornburg
Cummins Inc.
LandOfFree
System for producing charge flow and EGR fraction commands... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with System for producing charge flow and EGR fraction commands..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and System for producing charge flow and EGR fraction commands... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3261175