U.S. patent application number 12/002787 was filed with the patent office on 2008-06-26 for adaptive oxygen sensor methods, systems, and software.
Invention is credited to Wei Lu, Bradlee J. Stroia.
Application Number | 20080154481 12/002787 |
Document ID | / |
Family ID | 39544105 |
Filed Date | 2008-06-26 |
United States Patent
Application |
20080154481 |
Kind Code |
A1 |
Stroia; Bradlee J. ; et
al. |
June 26, 2008 |
Adaptive oxygen sensor methods, systems, and software
Abstract
One embodiment is a system operable to control entry of an
oxygen sensor into a learning mode. Further embodiments, forms,
objects, features, advantages, aspects, and benefits shall become
apparent from the following description and drawings.
Inventors: |
Stroia; Bradlee J.;
(Columbus, IN) ; Lu; Wei; (Columbus, IN) |
Correspondence
Address: |
KRIEG DEVAULT LLP
ONE INDIANA SQUARE, SUITE 2800
INDIANAPOLIS
IN
46204-2079
US
|
Family ID: |
39544105 |
Appl. No.: |
12/002787 |
Filed: |
December 18, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60876231 |
Dec 21, 2006 |
|
|
|
Current U.S.
Class: |
701/109 ; 60/276;
701/115 |
Current CPC
Class: |
F01N 11/007 20130101;
F01N 3/106 20130101; F02D 41/2441 20130101; F01N 2560/06 20130101;
F01N 2900/0422 20130101; F01N 3/0807 20130101; F02D 41/222
20130101; Y02T 10/40 20130101; F01N 11/002 20130101; F01N 13/009
20140601; F01N 2560/14 20130101; F02D 41/1454 20130101; Y02T 10/20
20130101; F01N 3/035 20130101; F02D 41/2474 20130101; F02D 41/2454
20130101; Y02T 10/47 20130101; F01N 2560/025 20130101; Y02T 10/12
20130101; F01N 2550/00 20130101 |
Class at
Publication: |
701/109 ; 60/276;
701/115 |
International
Class: |
F01N 11/00 20060101
F01N011/00; F01N 3/021 20060101 F01N003/021 |
Claims
1. A system comprising: an exhaust aftertreatment subsystem; an
oxygen sensor coupled to the exhaust aftertreatment subsystem; and
a controller operable to command the oxygen sensor to enter a
learning mode when an EGR condition is satisfied.
2. A system according to claim 1 wherein entry into the learning
mode further requires an exhaust pressure condition is
satisfied.
3. A system according to claim 1 wherein entry into the learning
mode further requires a regeneration condition is satisfied, an
exhaust pressure condition is satisfied, an EGR override condition
is satisfied, and an oxygen sensor fault condition is
satisfied.
4. A system according to claim 1 wherein the EGR condition includes
an information of a position of an EGR valve.
5. A system according to claim 1 wherein entry into the learning
mode further requires that at least 20 seconds have passed since a
regeneration event of the aftertreatment subsystem.
6. A system according to claim 1 wherein entry into the learning
mode further requires determination or evaluation of whether at
least one of the following errors is associated with the oxygen
sensor: a high threshold rationality error, a low threshold
rationality error, temperature error, a heater error, a supply
voltage error, and a communications interface timeout error.
7. A system according to claim 1 wherein the learning mode includes
executing instructions to reduce error of a measurement by the
oxygen sensor.
8. A system according to claim 1 wherein the learning mode includes
adjusting the oxygen sensor according to one or more engine
operating conditions.
9. A system according to claim 1 wherein entry into the learning
mode further requires determination or evaluation of whether at
least one of the following errors is associated with an oxygen
sensor: a high threshold rationality error, a low threshold
rationality error, temperature error, a heater error, a supply
voltage error, and a communications interface timeout error.
10. A system according to claim 1 wherein entry into the learning
mode further requires determination or evaluation of whether an ERG
valve is closed.
11. A system according to claim 1 wherein entry into the learning
mode further requires determination or evaluation of a pressure
differential across a diesel particulate filter.
12. A method comprising: evaluating a regeneration event condition;
evaluating an EGR mode condition; and controlling initiation of an
oxygen sensor learning mode based upon the evaluating a
regeneration event condition and the evaluating an EGR mode
condition.
13. A method according to claim 12 wherein the regeneration event
condition includes evaluation of whether time since a regeneration
event has exceeded a time threshold.
14. A method according to claim 12 wherein the EGR mode condition
includes evaluation of an information of EGR valve position.
15. A method according to claim 14 wherein the EGR mode condition
includes evaluation of a source of the information of EGR valve
position.
16. A method according to claim 12 further comprising evaluating a
pressure condition; wherein the controlling initiation of an oxygen
sensor learning mode is further based upon the evaluating a
pressure condition.
17. A method according to claim 16 wherein the evaluating a
pressure condition includes evaluating a pressure differential
across a diesel particulate filter.
18. A method according to claim 16 wherein the evaluating a
pressure condition includes evaluating ambient pressure.
19. A computer readable medium configured to store information
comprising: instructions executable to evaluate a regeneration
conditional; instructions executable to evaluate an exhaust gas
recirculation conditional; and instructions executable to control
initiation of an oxygen sensor learning mode based upon at least
one of the evaluation of the regeneration conditional and the
evaluation of the exhaust gas recirculation conditional.
20. A computer readable medium according to claim 19 operatively
coupled with an engine control module.
21. A computer readable medium according to claim 19 operatively
coupled with an engine control module and an internal combustion
engine.
22. A computer readable medium according to claim 19 operatively
coupled with an engine control module a diesel engine and a
vehicle.
Description
PRIORITY
[0001] The priority rights and benefits of U.S. Patent Application
No. 60/876,231 filed Dec. 21, 2006 are claimed, and this
application is incorporated by reference.
BACKGROUND
[0002] Internal combustion engines including diesel engines produce
a number of combustion products including particulates,
hydrocarbons ("HC"), carbon monoxide ("CO"), oxides of nitrogen
("NOx"), oxides of sulfur ("SOx") and others. Future diesel engines
may be required to reduce these and other emissions. Aftertreatment
systems may include oxygen sensors operable to measure or sense
O.sub.2 in exhaust in order to achieve desired efficiency and/or
desired regeneration of aftertreatment system devices. There is a
need for adaptive oxygen sensor methods, systems, and software.
SUMMARY
[0003] One embodiment is a system operable to control entry of an
oxygen sensor into a learning mode. Further embodiments, forms,
objects, features, advantages, aspects, and benefits shall become
apparent from the following description and drawings.
BRIEF DESCRIPTION OF THE FIGURES
[0004] FIG. 1 is a schematic of an integrated engine-exhaust
aftertreatment system.
[0005] FIG. 2 is a schematic of an integrated engine-exhaust
aftertreatment system operatively coupled with an engine control
unit.
[0006] FIG. 3 is a diagram of logic operable in connection with an
oxygen sensor.
[0007] FIG. 4 is a diagram of counter logic operable in connection
with an oxygen sensor.
[0008] FIG. 5 is a diagram of block 500 of FIG. 3.
[0009] FIG. 6 is a diagram of block 600 of FIG. 3.
[0010] FIG. 7 is a diagram of block 700 of FIG. 3.
[0011] FIG. 8 is a diagram of block 800 of FIG. 3.
[0012] FIG. 9 is a diagram of block 900 of FIG. 3.
DETAILED DESCRIPTION
[0013] For the purposes of promoting an understanding of the
principles of the invention, reference will now be made to the
embodiments illustrated in the drawings and specific language will
be used to describe the same. It will nevertheless be understood
that no limitation of the scope of the invention is thereby
intended, such alterations and further modifications in the
illustrated embodiments, and such further applications of the
principles of the invention as illustrated therein being
contemplated as would normally occur to one skilled in the art to
which the invention relates.
[0014] With reference to FIG. 1, there is illustrated a schematic
of a preferred integrated engine-exhaust aftertreatment system 10
provided in a vehicle 7. The aftertreatment subsystem 14 includes a
diesel oxidation catalyst 16 which is preferably a close coupled
catalyst but could be other types of catalyst units such as a
semi-close coupled catalyst, a NOx adsorber or lean NOx trap 18,
and a diesel particulate filter 20 which are in flow series
communication and receive and treat exhaust output from engine
12.
[0015] The diesel oxidation catalyst unit 16 is preferably a flow
through device that includes a honey-comb like substrate. The
substrate has a surface area that includes a catalyst. As exhaust
gas from the engine 12 traverses the catalyst, CO, gaseous HC and
liquid HC (unburned fuel and oil) are oxidized. The result of this
process is that these pollutants are converted to carbon dioxide
and water. During operation, the diesel oxidation catalyst unit 16
is heated to a desired temperature value.
[0016] The NOx adsorber 18 is operable to adsorb NOx and SOx
emitted from engine 12 to reduce emissions into the atmosphere. The
NOx adsorber 18 preferably includes catalyst sites which catalyze
oxidation reactions and storage sites which store compounds. After
NOx adsorber 18 reaches a certain storage capacity it may be
regenerated through deNOx and/or deSOx processes.
[0017] The diesel particulate filter 20 may include one or more of
several types of particle filters. The diesel particulate filter 20
is utilized to capture unwanted diesel particulate matter from the
flow of exhaust gas exiting the engine 12. Diesel particulate
matter includes sub-micron size particles found in diesel exhaust,
including both solid and liquid particles, and may be classified
into several fractions including: inorganic carbon (soot), organic
fraction (often referred to as SOF or VOF), and sulfate fraction
(hydrated sulfuric acid). The diesel particulate filter 20 may be
regenerated at regular intervals by oxidizing the particulates
trapped by the diesel particulate filter 20.
[0018] With reference to FIG. 2, there is illustrated a schematic
of integrated engine-exhaust aftertreatment system 10 operatively
coupled with an engine control unit ("ECU") 28. At least one
temperature sensor 60 is connected with the diesel oxidation
catalyst unit 16 for measuring the temperature of the exhaust gas
as it enters the diesel oxidation catalyst unit 16. In other
embodiments, two temperature sensors 60 are used, one at the
entrance to or upstream from the diesel oxidation catalyst unit 16
and another at the exit or downstream from the diesel oxidation
catalyst unit 16. Information from temperature sensor(s) 60 is
provided to ECU 28 and used to calculate the temperature of the
diesel oxidation catalyst unit 16.
[0019] A first NOx temperature sensor 62 senses the temperature of
flow entering or upstream of NOx adsorber 18 and provides a signal
to ECU 28. A second NOx temperature sensor 64 senses the
temperature of flow exiting or downstream of NOx adsorber 18 and
provides a signal to ECU 28. NOx temperature sensors 62 and 64 are
used to monitor the temperature of the flow of gas entering and
exiting the NOx adsorber 18 and provide signals that are indicative
of the temperature of the flow of exhaust gas to the ECU 28. An
algorithm may be used by the ECU 28 to determine the operating
temperature of the NOx adsorber 18.
[0020] A first oxygen sensor 66 is positioned in fluid
communication with the flow of exhaust gas entering or upstream
from the NOx adsorber 18 and a second oxygen sensor 68 is
positioned in fluid communication with the flow of exhaust gas
exiting or downstream of the NOx adsorber 18. Oxygen sensors 66 and
68 could be a type of oxygen sensor, for example, a universal
exhaust gas oxygen sensor or lambda sensor. Oxygen sensors 66 and
68 preferably include or are associated with heaters which heat
them to a desired operating temperature. The oxygen sensors 66 and
68 are connected with the ECU 28 and generate electric signals that
are indicative of the amount of oxygen contained in the flow of
exhaust gas. The oxygen sensors 66 and 68 allow the ECU 28 to
monitor air-fuel ratios also over a wide range thereby allowing ECU
28 to determine a value associated with the exhaust gas entering
and exiting the NOx adsorber 18. Additional embodiments contemplate
oxygen sensors positioned at other locations, for example, in a
system including a saline NOx catalyst, oxygen sensors could be
positioned to sense input and output flow of the saline NOx
catalyst. The oxygen sensors 66 and 68 can enter into a learning
mode or autozero mode. In such modes, the oxygen sensors can
adaptively learn the appropriate calibrations for an aftertreatment
system to which they are coupled. Learning modes may include
calibration, zeroing and other operations which assist in or
provide increased accuracy and/or reduced error in measurement
and/or estimation of oxygen levels, and/or in adapting oxygen
sensor operation to a mode of system operation.
[0021] Engine 12 includes a fuel injection system 90 that is
connected with, and controlled by the ECU 28. Fuel injection system
90 delivers fuel into the cylinders of the engine 12. Various types
of fuel injection systems may be utilized in the present invention,
including, but not limited to, pump-line-nozzle injection systems,
unit injector and unit pump systems, high pressure common rail fuel
systems, common rail fuel injection systems and others. The timing
of the fuel injection, the amount of fuel injected, the number and
timing of injection pulses, are preferably controlled by fuel
injection system 90 and/or ECU 28.
[0022] With reference to FIG. 3, there is illustrated an oxygen
sensor learning mode control diagram 300 which can be executed by a
controller such as ECU 28. Oxygen sensor learning control diagram
300 includes block 500 which receives inputs 501, 502, and 503, and
outputs to variable 599; block 600 which receives input 601, and
outputs to variable 699; block 700 which receives inputs 701, 702,
703, 704, 705, 706, 707, 708, 709, and 710, and outputs to variable
799; block 800 which receives inputs 801 and 802, and outputs to
variable 899; and block 900 which receives inputs 901 and 902, and
outputs to variable 799. Block 500 determines whether the engine is
in motoring condition. Block 600 determines whether there has been
no regeneration for a specified time period. Block 700 determines
whether there are oxygen sensor faults. Block 800 determines
whether EGR is overridden. Block 900 determines whether exhaust
pressure is within specified limits. Blocks, 500, 600, 700, 800,
and 900 and their inputs and outputs are further described below in
connection with FIGS. 5, 6, 7, 8, and 9, respectively.
[0023] Variables 599, 699, 799, 899, and 999 are provided to
conditional 310 which is a Boolean AND operator. Conditional 310
outputs to variable 390, the oxygen autozero flag, which can be
used to control whether the oxygen sensors enter learning mode or
autozero. Variable 390 is provided to the bottom input of switch
380. Variable 382 is provided to the top input of switch 380.
Variable 382 is an autozero override value. Variable 381 is
provided to the select input of switch 380. Variable 381 is an
autozero override. When variable 381 is false switch 380 will
output the value of its bottom input. When variable 381 is true
switch 380 will output the value of its top input. The output of
switch 380 is provided to variable 399, the autozero command
variable. When the value of variable 399 is false the learning mode
or autozero mode will not run. When the value of variable 399 is
true the learning mode or autozero mode will run.
[0024] With reference to FIG. 4, there is illustrated a diagram of
autozero counter logic 400. Variable 399, the
Smart_O2_AutoZero_Command variable, is provided to conditional 410
and to debounce 411 the output of which is also provided to
conditional 410. When the conditions are satisfied for an O2 learn
incident, variable 399 is true. Conditional 410 detects the
presence of a rising edge by testing whether variable 399> the
output of debounce 411. The output of conditional 410 is provided
to conditional 430.
[0025] Variable 401, the time since engine start, is provided to
conditional 420 which tests whether variable 401>=30 (or another
threshold time). The output of conditional 420 is provided to
conditional 430. Conditional 430 is a Boolean AND the output of
which is provided to the increment condition input of counter 440
and to the increment condition input of counter 450. An increment
value is provided to the increment value input of counter 440, and
the decrement condition and decrement value inputs of counter 440
are disabled. In other embodiments, counter 440 could be configured
to decrement. A max limit value is provided to max limit input of
counter/timer 440. The output of counter 440 is provided to
variable 449. If a rising edge is detected, and the time since
engine start is 30 minutes or greater, the count is increment by 1,
since under these conditions the sensor should learn.
[0026] Variable 409, a counter reset variable, is provided to
conditional 460 and to debounce 461 the output of which is also
provided to conditional 460. Conditional 460 tests whether variable
409>the output of debounce 461. The output of conditional 460 is
provided to the reset inputs of counter 440 and counter 450. An
increment value is provided to the increment value input of counter
450, and the decrement condition and decrement value inputs of
counter 450 are disabled. In other embodiments, counter 450 could
be configured to decrement. A max limit value is provided to max
limit input of counter 440. The output of counter 440 is provided
to variable 449 which is provided to the powerdown preset input of
counter 450. The powerdown preset set the counter output to the
powerdown value, no matter what input is. Variable 449, the
V_Smart_O2_AutoZero_Count variable, is a count of how many times
that an oxygen sensor has learned in a current drive cycle.
Variable 459, the P_Smart_O2_AutoZero_Count, is a count of how many
times that an oxygen sensor has learned in total. Variable 459 can
be used to enable a mass air flow or MAF learn process.
[0027] With reference to FIG. 5, there is illustrated a diagram of
block 500 which is operable to determine whether engine motoring
conditions meet fueling, engine speed, and fresh air flow criteria.
For example, one embodiment requires that engine speed has been
greater than 400 rpm for 30 minutes, engine temperature has been
greater than 80.degree. C. for 30 minutes, and engine fueling is
zero.
[0028] Variables 501, 502, and 5023 are input to block 500.
Variable 501 is a function of the cylinder fueling. Variable 501 is
provided to conditional 510. Conditional 510 tests whether variable
501=zero. The output of conditional 510 is provided to the
increment condition input of counter/timer 520 and the inverse of
the output of conditional 510 is provided to the reset input of
counter/timer 520. An increment value is provided to the increment
value input of counter/timer 520, and the decrement condition and
decrement value inputs of counter/timer 520 are disabled. In other
embodiments, counter/timer 520 could be configured to decrement.
Variable 512, the no fuel time max, is provided to the max limit
input of counter/timer 520 and to conditional 522. The counter
output of counter/timer 520 is provided to conditional 522.
Conditional 522 tests whether the output of counter/timer 520 is
>=variable 512. The output of conditional 522 is provided to
variable 524, the no fuel flag, and to conditional 540.
[0029] Variable 502 is a function of filtered engine speed.
Variable 502 is provided to conditional 513, conditional 514, and
two-dimensional lookup table 511. Two-dimensional lookup table 511
outputs a no fuel time value to variable 512 based upon the engine
speed value received at its input. Conditional 513 tests whether
variable 502<=variable 504. Variable 504 is a maximum threshold
for engine speed. Conditional 514 tests whether variable
502>=variable 506. Variable 504 is a minimum threshold for
engine speed. The output of conditional 513 and the output of
conditional 514 are provided to conditional 515. Conditional 515 is
a Boolean AND operator. The output of conditional 515 is provided
to variable 525. Variable 525 is true when variable 502 is within
the maximum threshold and within the minimum threshold, and
otherwise false. The value of variable 525 is provided to
conditional 540.
[0030] Variable 503 is a function of fresh air flow. Variable 503
is provided to conditional 516 and conditional 517. Conditional 516
tests whether variable 503<=variable 506. Variable 506 is a
maximum threshold for fresh air flow. Conditional 517 tests whether
variable 503>=variable 507. Variable 507 is a minimum threshold
for fresh air flow. The output of conditional 516 and the output of
conditional 517 are provided to conditional 518. Conditional 518 is
a Boolean AND operator. The output of conditional 518 is provided
to variable 526, the air flow in range variable. Variable 526 is
true when variable 503 is within the maximum threshold and within
the minimum threshold, and otherwise false. The value of variable
526 is provided to conditional 540.
[0031] Conditional 540 is a Boolean AND operator. The output of
conditional 540 is provided to the bottom input of switch 580.
Variable 582 is provided to the top input of switch 580. Variable
582 is an engine motoring override value. Variable 581 is provided
to the select input of switch 580. Variable 581 controls engine
motoring override. When variable 581 is false switch 580 will
output the value of its bottom input. When variable 581 is true
switch 580 will output the value of its top input. The output of
switch 580 is provided to variable 599, the engine motoring flag,
which is output from block 500 as illustrated and described above
in connection with FIG. 3.
[0032] With reference to FIG. 6, there is illustrated a diagram of
block 600 which is operable to determine whether there have been no
regenerations for at least a threshold period of time, for example,
20 seconds. Variable 601, which is a function of the operating
mode, is input to block 600. Conditional 610 tests whether variable
601=variable 602. Variable 602 is a value which indicates that the
operating mode is not a regeneration operating mode.
[0033] The output of conditional 610 is input to the increment
condition input of counter/timer 620. An increment value is
provided to the increment value input of counter/timer 620, and the
decrement condition and decrement value inputs of counter/timer 620
are disabled. In other embodiments, counter/timer 620 could be
configured to decrement. The inverse of the output of conditional
610 is input to the reset input of counter/timer 620. Variable 603
is a no regeneration time threshold value which is input to the max
limit input of counter/timer 620 and to conditional 630.
Conditional 630 tests whether the counter output of counter/timer
620>=variable 603 and outputs the result.
[0034] The output of conditional 630 is provided to variable 690
and to the bottom input of switch 680. Variable 682 is provided to
the top input of switch 680. Variable 682 is a no regeneration
override value. Variable 681 is provided to the select input of
switch 680. Variable 681 controls the no regeneration override.
When variable 681 is false switch 680 will output the value of its
bottom input. When variable 681 is true switch 680 will output the
value of its top input. The output of switch 680 is provided to
variable 699, the no regeneration flag, which is output from block
600 as illustrated and described above in connection with FIG.
3.
[0035] With reference to FIG. 7, there is illustrated a diagram of
block 700 which is operable to determine whether any oxygen sensor
faults are true. Variables 701, 702, 703, 704, 705, 706, 707, 708,
709, and 710 are input to block 700. Variable 701 indicates whether
a high threshold rationality error for a first oxygen sensor (such
as oxygen sensor 66) is present. Variable 702 indicates whether a
low threshold rationality error for the first sensor is present.
Variable 703 indicates whether a high threshold rationality error
for a second oxygen sensor (such as oxygen sensor 68) is present.
Variable 704 indicates whether a low threshold rationality error
for the second oxygen sensor is present. Variable 705 indicates
whether a sensor error for the first oxygen sensor is present.
Variable 706 indicates whether a sensor error for the second oxygen
sensor is present. Variable 707 indicates whether a heater error
for the first oxygen sensor is present. Variable 708 indicates
whether a heater error for the second oxygen sensor is present.
Variable 709 indicates whether an oxygen sensor supply voltage
error is present. Variable 710 indicates whether a communications
interface time out error is present.
[0036] Variable 701 is input to conditional 711 which tests whether
variable 701=false and outputs the result of the test to flag
variable 721 and conditional 740. Variable 702 is input to
conditional 712 which tests whether variable 702=false and outputs
the result of the test to flag variable 722 and conditional 740.
Variable 703 is input to conditional 713 which tests whether
variable 703=false and outputs the result of the test to flag
variable 723 and conditional 740. Variable 704 is input to
conditional 714 which tests whether variable 704=false and outputs
the result of the test to flag variable 724 and conditional 740.
Variable 705 is input to conditional 715 which tests whether
variable 705=false and outputs the result of the test to flag
variable 725 and conditional 740. Variable 706 is input to
conditional 716 which tests whether variable 706=false and outputs
the result of the test to flag variable 726 and conditional 740.
Variable 707 is input to conditional 717 which tests whether
variable 707=false and outputs the result of the test to flag
variable 727 and conditional 740. Variable 708 is input to
conditional 718 which tests whether variable 708=false and outputs
the result of the test to flag variable 728 and conditional 740.
Variable 709 is input to conditional 719 which tests whether
variable 709=false and outputs the result of the test to flag
variable 729 and conditional 740. Variable 710 is input to
conditional 720 which tests whether variable 710=false and outputs
the result of the test to flag variable 730 and conditional
740.
[0037] Conditional 740 is a Boolean AND operator which is provided
to variable 790 and the bottom input of switch 780. Variable 782 is
provided to the top input of switch 780. Variable 782 is an oxygen
sensor override value. Variable 781 is provided to the select input
of switch 780. Variable 781 controls oxygen sensor error override.
When variable 781 is false switch 780 will output the value of its
bottom input. When variable 781 is true switch 780 will output the
value of its top input. The output of switch 780 is provided to
variable 799, the oxygen sensor error flag, which is output from
block 700 as illustrated and described above in connection with
FIG. 3.
[0038] With reference to FIG. 8, there is illustrated a diagram of
block 800 which is operable to determine whether EGR conditions are
in a desired state. Variables 801 and 802 are input to block 800.
Variable 801 is a function of whether the EGR valve is closed.
Variable 801 is provided to conditional 810. Conditional 810 tests
whether variable 801=variable 803. Variable 803 is the value which
indicates that the EGR valve is closed. The output of conditional
810 is provided to conditional 830.
[0039] Variable 802 is a function of the source from which the EGR
valve position information is determined. Variable 802 is provided
to conditional 820. Conditional 820 tests whether variable
802=variable 804. Variable 804 is a value that specifies the
desired source of the EGR valve position information. The output of
conditional 820 is provided to conditional 830. Conditional 830 is
a Boolean AND operator. The output of conditional 850 is provided
to variable 890, which stores an EGR condition value.
[0040] Variable 890 is provided to the bottom input of switch 880.
Variable 882 is provided to the top input of switch 880. Variable
882 is an EGR condition override value. Variable 881 is provided to
the select input of switch 880. Variable 881 controls the EGR
condition override. When variable 881 is false switch 880 will
output the value of its bottom input. When variable 881 is true
switch 880 will output the value of its top input. The output of
switch 880 is provided to variable 899, the EGR condition flag,
which is output from block 800 as illustrated and described above
in connection with FIG. 3.
[0041] With reference to FIG. 9, there is illustrated a diagram of
block 900 which is operable to determine whether exhaust pressure
conditions are within desired limits. Variables 901 and 902 are
input to block 900. Variable 901 is a function of the pressure
differential across a diesel particulate filter. Variable 901 is
provided to conditional 910 and conditional 920. Conditional 910
tests whether variable 901<=variable 903. Variable 903 is a
maximum threshold for the pressure differential across a diesel
particulate filter. Conditional 920 tests whether variable
901>=variable 904. Variable 904 is a minimum threshold for the
pressure differential across a diesel particulate filter. The
output of conditional 910 and the output of conditional 920 are
provided to conditional 950. Conditional 950 is a Boolean AND
operator. The output of conditional 950 is provided to variable
951. Variable 951 is true when variable 901 is within the maximum
threshold and within the minimum threshold, and otherwise false.
The value of variable 951 is provided to conditional 970.
[0042] Variable 902 is a function of the ambient air pressure.
Variable 902 is provided to conditional 930 and conditional 940.
Conditional 930 tests whether variable 902<=variable 905.
Variable 905 is a maximum threshold for the pressure of the ambient
air. Conditional 920 tests whether variable 902>=variable 906.
Variable 904 is a minimum threshold for the pressure of the ambient
air. The output of conditional 930 and the output of conditional
940 are provided to conditional 960. Conditional 960 is a Boolean
AND operator. The output of conditional 960 is provided to variable
961. Variable 961 is true when variable 902 is within the maximum
threshold and within the minimum threshold, and otherwise false.
The value of variable 951 is provided to conditional 970.
[0043] Conditional 970 is a Boolean AND operator. The output of
conditional 970 is provided to the bottom input of switch 980.
Variable 982 is provided to the top input of switch 980. Variable
982 a pressure condition override value. Variable 981 is provided
to the select input of switch 980. Variable 981 controls a pressure
condition override. When variable 981 is false switch 980 will
output the value of its bottom input. When variable 981 is true
switch 980 will output the value of its top input. The output of
switch 980 is provided to variable 999, the pressure condition
flag, which is output from block 900 as illustrated and described
above in connection with FIG. 3.
[0044] While the invention has been illustrated and described in
detail in the drawings and foregoing description, the same is to be
considered as illustrative and not restrictive in character, it
being understood that only the preferred embodiments have been
shown and described and that all changes and modifications that
come within the spirit of the inventions are desired to be
protected. It should be understood that while the use of words such
as preferable, preferably, preferred or more preferred utilized in
the description above indicate that the feature so described may be
more desirable, it nonetheless may not be necessary and embodiments
lacking the same may be contemplated as within the scope of the
invention, the scope being defined by the claims that follow. In
reading the claims, it is intended that when words such as "a,"
"an," "at least one," or "at least one portion" are used there is
no intention to limit the claim to only one item unless
specifically stated to the contrary in the claim. When the language
"at least a portion" and/or "a portion" is used the item can
include a portion and/or the entire item unless specifically stated
to the contrary.
* * * * *