U.S. patent application number 11/939000 was filed with the patent office on 2008-07-03 for method for verifying the functionality of the components of a diesel particulate filter system.
This patent application is currently assigned to Detroit Diesel Corporation. Invention is credited to Matthew T. Baird, Dennis J. Grace, Frank S. Groer, Jeffery S. Hawkins, Donald E. Keski-Hynnila, Zornitza P. Pavlova-MacKinnon, Reinhard Pfundt, Amr M. Radwan, Kevin D. Sisken, Heather A. Staley, Min Sun, Harald Wedler, Peter Zagone, Mark A. Zurawski.
Application Number | 20080155970 11/939000 |
Document ID | / |
Family ID | 39582011 |
Filed Date | 2008-07-03 |
United States Patent
Application |
20080155970 |
Kind Code |
A1 |
Keski-Hynnila; Donald E. ;
et al. |
July 3, 2008 |
METHOD FOR VERIFYING THE FUNCTIONALITY OF THE COMPONENTS OF A
DIESEL PARTICULATE FILTER SYSTEM
Abstract
A method for verifying the functionality of the components for a
diesel particulate filter system based upon engine speed, engine
torque, inlet and outlet exhaust pressure at the diesel particulate
filter. Various sensor signals are compared to calibratable values
in memory for a determination whether the diesel particulate filter
system is functional.
Inventors: |
Keski-Hynnila; Donald E.;
(Canton, MI) ; Hawkins; Jeffery S.; (Farmington
Hills, MI) ; Wedler; Harald; (Neuhausen, DE) ;
Pfundt; Reinhard; (Ansbach, DE) ; Groer; Frank
S.; (Stuttgard, DE) ; Zurawski; Mark A.;
(Northville, MI) ; Radwan; Amr M.; (Canton,
MI) ; Zagone; Peter; (Huntington, MI) ;
Sisken; Kevin D.; (Saline, MI) ; Baird; Matthew
T.; (Canton, MI) ; Sun; Min; (Troy, MI)
; Pavlova-MacKinnon; Zornitza P.; (Farmington Hills,
MI) ; Grace; Dennis J.; (West Bloomfield, MI)
; Staley; Heather A.; (Garden City, MI) |
Correspondence
Address: |
RADER, FISHMAN & GRAUER PLLC
39533 WOODWARD AVENUE, SUITE 140
BLOOMFIELD HILLS
MI
48304-0610
US
|
Assignee: |
Detroit Diesel Corporation
Detroit
MI
|
Family ID: |
39582011 |
Appl. No.: |
11/939000 |
Filed: |
November 13, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60877307 |
Dec 27, 2006 |
|
|
|
Current U.S.
Class: |
60/295 ; 60/285;
60/297 |
Current CPC
Class: |
F01N 13/0097 20140603;
F01N 2250/02 20130101; F01N 2560/14 20130101; Y02T 10/47 20130101;
F01N 3/106 20130101; F01N 2560/06 20130101; F01N 11/002 20130101;
G01M 15/102 20130101; F02B 37/00 20130101; Y02T 10/40 20130101;
F01N 2560/08 20130101 |
Class at
Publication: |
60/295 ; 60/297;
60/285 |
International
Class: |
G01M 15/10 20060101
G01M015/10; F01N 3/00 20060101 F01N003/00 |
Claims
1. A method to perform diagnostics on an electronically controlled
diesel engine equipped with an electronic control unit (ECU) having
memory and tables resident therein; said engine further equipped
with an ignition and at least one sensor adapted to transmit data
signals from a diesel particulate filter system having a catalyst
with an inlet and an outlet; said method comprising: determining
pressure from at least one of said diesel particulate inlet and
said outlet at when said engine is at least at one of low engine
speed and low engine torque; determining pressure from at least one
of said diesel particulate inlet and said outlet when said engine
is at least at one of high engine speed and high engine torque; and
comparing at least one of said diesel particulate inlet and outlet
pressure between low engine speed and low engine torque with at
least one of said diesel particulate inlet and outlet pressure at
high engine speed ad high engine torque with at lease one of diesel
particulate inlet and outlet pressure at high engine speed and at
least one of calibratable minimum delta of diesel particulate inlet
and outlet pressure in memory in said ECU with a calibratable
minimum period of time in memory in said ECU to determine whether
said sensor is accurate.
2. The method of claim 1, wherein for diesel particulate inlet
pressure at low engine speed, low engine torque, the time period is
greater than a first calibratable soak time when the engine is not
in regeneration mode.
3. The method of claim 2, wherein for diesel particulate inlet
pressure at high engine speed high engine torque, the time period
is greater than a second calibratable soak time when the engine is
not in regeneration mode.
4. The method of claim 3, wherein said first calibratable soak time
and said second calibratable soak time are substantially the
same.
5. The method of claim 1, wherein when said sensor is determined to
be inaccurate, a fault is set in the ECU and a maximum available
engine torque is reduced to a calibratable percentage of normally
available maximum engine torque.
6. The method of claim 1, wherein when said engine is at idle and
is not in diesel particulate filter regeneration mode; further
including determining whether the diesel particulate filter inlet
pressure is greater than a maximum calibratable threshold value in
memory to determine whether the diesel particulate filter sensor
has drifted high.
7. The method of claim 1, wherein when said engine is in idle and
is not in diesel particulate filter regeneration mode; further
including determining whether the diesel particulate filter inlet
pressure is less than a lower calibratable threshold value in
memory to determine whether the diesel particulate filter sensor
has drifted low.
8. The method of claim 1, wherein at least one said data signal is
the diesel particulate filter inlet temperature taken in a time
period between when said ignition is on to when said engine is
cranking.
9. The method of claim 8, further including extending said time
period to a calibratable time period after said engine is
cranking.
10. The method of claim 8, wherein said temperature data signals
depend on engine soak histories.
11. The method of claim 8, wherein an absolute temperature
differential between any three of the data signal sensors is
greater than a calibratable threshold.
12. The method of claim 1, wherein a determination is made as to
which sensor is out of range as compared to two other temperature
sensors and an appropriate rationality fault is logged and an
appropriate warning indicator is activated.
13. The method of claim 1, wherein temperature of said catalyst
inlet exhaust are compared between high and low temperatures
conditions and the engine is not in regeneration mode and the time
is greater than a calibratable minimum soak time.
14. The method of claim 14, wherein the catalyst inlet temperature
is determined at low engine speed and low engine torque at a
minimum first calibratable soak time and compared with the catalyst
inlet temperature at high speed and high engine torque at a minimum
second calibratable soak time.
15. The method of claim 14, wherein said first calibratable soak
time and said second calibratable soak time are different.
16. The method of claim 1, wherein said catalyst inlet temperatures
are logged in memory and default values are used upon each new
ignition cycle.
17. The method of claim 1, wherein post diesel particulate filter
exhaust gas temperatures are compared between low and high
temperature conditions to determine whether a sensor has
drifted.
18. The method of claim 1, wherein if the temperature at low engine
speed, low engine torque is subtracted from the temperature at high
engine speed, high engine torque is less than a calibratable
minimum threshold, at least one temperature sensor is stuck.
19. The method of claim 1, wherein if the engine is not in
regeneration mode, and the diesel particulate outlet pressure is
below a calibratable minimum threshold, the sensor has drifted
low.
20. The method of claim 1, wherein if the engine is at high speed
and high torque, and said engine not in idle mode and is not in
regeneration mode, and said diesel particulate outlet pressure is
above a calibratable maximum threshold, the sensor has drifted
high.
21. The method of claim 1, wherein if said engine is not operating
and the difference between the diesel particulate inlet pressure
and the diesel particulate outlet pressure is greater than a
calibratable maximum threshold value, a fault is logged and a
warning indicator is activated.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims priority to U.S. Provisional
Application Ser. No. 60/877,307 filed on Dec. 27, 2006, the
contents of which are incorporated herein in their entirety.
BACKGROUND OF THE INVENTION
[0002] Industry and legislative initiatives have, in recent years,
increasing focused on the need to reduce exhaust emissions from
internal combustion engines. Industry efforts have led to the
introduction of catalytic converters, particulate filters and other
technologies to reduce emissions and increase fuel economy. There
is a continuing advantage to keep those components in repair to
ensure that the environmental goals of industry and legislatures
are met during the operating life of a vehicle. Warranty issues are
reduced when the vehicle is kept in repair, and environmental goals
are addressed when the exhaust emissions are controlled.
[0003] The present invention relates to a method for verifying the
functionality of the components of a diesel a particulate filter
system.
[0004] The present invention further relates to a method to perform
rationality checks on sensors in an exhaust system of a diesel
engine, particularly the diesel particulate filter system, to
determine whether the sensors are transmitting accurate sensor
readings.
[0005] The present invention further relates to a method to perform
rationality checks on the sensors in a diesel particulate filter
system to determine whether they are transmitting accurate data
signals and that the exhaust system is in compliance with emissions
requirements. If the sensors are determined to be inaccurate, a
fault is logged in the engine control unit and a warning indicator
may be activated alerting the operator of the need to service the
vehicle.
BRIEF SUMMARY OF THE INVENTION
[0006] The present invention is directed to a method to perform
diagnostics on an electronically controlled diesel engine equipped
with an electronic control unit (ECU) having memory and tables
resident therein. The engine is further equipped with an ignition
and at least one sensor adapted to transmit data signals from a
diesel particulate filter system having a catalyst with an inlet
and an outlet. The method comprises:
[0007] determining pressure from at least one of said diesel
particulate inlet and said outlet at when said engine is at least
at one of low engine speed and low engine torque;
[0008] determining pressure from at least one of said diesel
particulate inlet and said outlet when said engine is at least at
one of high engine speed and high engine torque;
[0009] comparing at least one of said diesel particulate inlet and
outlet pressure between low engine speed and low engine torque with
at least one of said diesel particulate inlet and outlet pressure
at high engine speed ad high engine torque with at lease one of
diesel particulate inlet and outlet pressure at high engine speed
and at least one of calibratable minimum delta of diesel
particulate inlet and outlet pressure in memory in said ECU with a
calibratable minimum period of time in memory in said ECU to
determine whether said sensor is accurate.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a schematic representation of a heavy duty diesel
engine with an exhaust system that includes a diesel particulate
filter system.
[0011] FIG. 2 is a representation of a software flow chart of one
method according to the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)
[0012] FIG. 1 illustrates a vehicle powertrain system 10 in
accordance with one non-limiting aspect of the present invention.
The system 10 may provide power for driving any number of vehicles,
including on-highway trucks, construction equipment, marine
vessels, stationary generators, automobiles, trucks,
tractor-trailers, boats, recreational vehicle, light and heavy-duty
work vehicles, and the like.
[0013] The system 10 may be referred to as an internal combustion
driven system wherein fuels, such as gasoline and diesel fuels, are
burned in a combustion process to provide power, such as with a
spark or compression ignition engine 14. The engine 14 may be a
diesel engine that includes a number of cylinders 18 into which
fuel and air are injected for ignition as one skilled in the art
will appreciate. The engine 14 may be a multi-cylinder compression
ignition internal combustion engine, such as a 4, 6, 8, 12, 16, or
24 cylinder diesel engines, for example. It should be noted,
however, that the present invention is not limited to a particular
type of engine or fuel.
[0014] Exhaust gases generated by the engine 14 during combustion
may be emitted through an exhaust system 20. The exhaust system 20
may include any number of features, including an exhaust manifold
and passageways to deliver the emitted exhaust gases to a
particulate filter assembly 30, which in the case of diesel engines
is commonly referred to as a diesel particulate filter. Optionally,
the system 20 may include a turbocharger proximate the exhaust
manifold for compressing fresh air delivery into the engine 14. The
turbocharger, for example, may include a turbine 32 and a
compressor 34, such as a variable geometry turbocharger (VGT)
and/or a turbo compound power turbine. Of course, the present
invention is not limited to exhaust systems having turbochargers or
the like.
[0015] The particulate filter assembly 30 may be configured to
capture particulates associated with the combustion process. In
more detail, the particulate filter assembly 30 may include an
oxidation catalyst (OC) canister 36, which in includes an OC 38,
and a particulate filter canister 42, which includes a particulate
filter 44. The canisters 36, 42 may be separate components joined
together with a clamp or other feature such that the canisters 36,
42 may be separated for servicing and other operations. Of course,
the present invention is not intended to be limited to this
exemplary configuration for the particulate filter assembly 30.
Rather, the present invention contemplates the particulate filter
assembly including more or less of these components and features.
In particular, the present invention contemplates the particulate
filter assembly 30 including only the particulate filter 44 and not
necessarily the OC canister 36 or substrate 38 and that the
particulate filter 44 may be located in other portions of the
exhaust system 20, such as upstream of the turbine 32.
[0016] The OC 38, which for diesel engines is commonly referred to
as a diesel oxidation catalyst, may oxidize hydrocarbons and carbon
monoxide included within the exhaust gases so as to increase
temperatures at the particulate filter 44. The particulate filter
44 may capture particulates included within the exhaust gases, such
as carbon, oil particles, ash, and the like, and regenerate the
captured particulates if temperatures associated therewith are
sufficiently high. In accordance with one non-limiting aspect of
the present invention, one object of the particulate filter
assembly 30 is to capture harmful carbonaceous particles included
in the exhaust gases and to store these contaminates until
temperatures at the particulate filter 44 favor oxidation of the
captured particulates into a gas that can be discharged to the
atmosphere.
[0017] The OC and particulate filter canisters 36, 42 may include
inlets and outlets having defined cross-sectional areas with
expansive portions there between to store the OC 38 and particulate
filter 44, respectively. However, the present invention
contemplates that the canisters 36, 42 and devices therein may
include any number configurations and arrangements for oxidizing
emissions and capturing particulates. As such, the present
invention is not intended to be limited to any particular
configuration for the particulate filter assembly 30.
[0018] To facilitate oxidizing the capture particulates, a doser 50
may be included to introduce fuel to the exhaust gases such that
the fuel reacts with the OC 38 and combusts to increase
temperatures at the particulate filter 44, such as to facilitate
regeneration. For example, one non-limiting aspect of the present
invention contemplates controlling the amount of fuel injected from
the doser as a function of temperatures at the particulate filter
44 and other system parameters, such as air mass flow, EGR
temperatures, and the like, so as to control regeneration. However,
the present invention also contemplates that fuel may be included
within the exhaust gases through other measures, such as by
controlling the engine 14 to emit fuel with the exhaust gases.
[0019] An air intake system 52 may be included for delivering fresh
air from a fresh air inlet 54 through an air passage to an intake
manifold for introduction to the engine 14. In addition, the system
52 may include an air cooler or charge air cooler 56 to cool the
fresh air after it is compressed by the compressor 34. Optionally,
a throttle intake valve 58 may be provided to control the flow of
fresh air to the engine 14. Optionally, the throttle intake valve
58 may also be provided to control the flow of EGR gases to the
engine 14 or control both fresh air and EGR gases 64 to the engine
14. The throttle valve 58 may be a manually or electrically
operated valve, such as one which is responsive to a pedal position
of a throttle pedal operated by a driver of the vehicle. There are
many variations possible for such an air intake system and the
present invention is not intended to be limited to any particular
arrangement. Rather, the present invention contemplates any number
of features and devices for providing fresh air to the intake
manifold and cylinders, including more or less of the foregoing
features.
[0020] An exhaust gas recirculation (EGR) system 64 may be
optionally provided to recycle exhaust gas to the engine 14 for
mixture with the fresh air. The EGR system 64 may selectively
introduce a metered portion of the exhaust gasses into the engine
14. The EGR system 64, for example, may dilute the incoming air
charge and lower peak combustion temperatures to reduce the amount
of oxides of nitrogen produced during combustion. The amount of
exhaust gas to be recirculated may be controlled by controlling an
EGR valve 66 and/or in combination with other features, such as the
turbocharger. The EGR valve 66 may be a variable flow valve that is
electronically controlled. There are many possible configurations
for the controllable EGR valve 66 and embodiments of the present
invention are not limited to any particular structure for the EGR
valve 66.
[0021] The EGR system 64 in one non-limiting aspect of the present
invention may include an EGR cooler passage 70, which includes an
EGR cooler 72, and an EGR cooler bypass 74. The EGR valve 66 may be
provided at the exhaust manifold to meter exhaust gas through one
or both of the EGR cooler passage 70 and bypass 74. Of course, the
present invention contemplates that the EGR system 64 may include
more or less of these features and other features for recycling
exhaust gas. Accordingly, the present invention is not intended to
be limited to any one EGR system and contemplates the use of other
such systems, including more or less of these features, such as an
EGR system having only one of the EGR cooler passage or bypass.
[0022] A cooling system 80 may be included for cycling the engine
14 by cycling coolant there through. The coolant may be sufficient
for fluidly conducting away heat generated by the engine 14, such
as through a radiator. The radiator may include a number of fins
through which the coolant flows to be cooled by air flow through an
engine housing and/or generated by a radiator fan directed thereto
as one skilled in the art will appreciated. It is contemplated,
however that the present invention may include more or less of
these features in the cooling system 80 and the present invention
is not intended to be limited to the exemplary cooling system
described above.
[0023] The cooling system 80 may operate in conjunction with a
heating system 84. The heating system 84 may include a heating
core, a heating fan, and a heater valve. The heating core may
receive heated coolant fluid from the engine 14 through the heater
valve so that the heating fan, which may be electrically
controllable by occupants in a passenger area or cab of a vehicle,
may blow air warmed by the heating core to the passengers. For
example, the heating fan may be controllable at various speeds to
control an amount of warmed air blown past the heating core whereby
the warmed air may then be distributed through a venting system to
the occupants. Optionally, sensors and switches 86 may be included
in the passenger area to control the heating demands of the
occupants. The switches and sensors may include dial or digital
switches for requesting heating and sensors for determining whether
the requested heating demand was met. The present invention
contemplates that more or less of these features may be included in
the heating system and is not intended to be limited to the
exemplary heating system described above.
[0024] A controller 92, such as an electronic control module or
engine control module, may be included in the system 10 to control
various operations of the engine 14 and other system or subsystems
associated therewith, such as the sensors in the exhaust, EGR, and
intake systems. Various sensors may be in electrical communication
with the controller via input/output ports 94. The controller 92
may include a microprocessor unit (MPU) 98 in communication with
various computer readable storage media via a data and control bus
100. The computer readable storage media may include any of a
number of known devices which function as read only memory 102,
random access memory 104, and non-volatile random access memory
106. A data, diagnostics, and programming input and output device
108 may also be selectively connected to the controller via a plug
to exchange various information therebetween. The device 108 may be
used to change values within the computer readable storage media,
such as configuration settings, calibration variables, instructions
for EGR, intake, and exhaust systems control and others.
[0025] The system 10 may include an injection mechanism 114 for
controlling fuel and/or air injection for the cylinders 18. The
injection mechanism 114 may be controlled by the controller 92 or
other controller and comprise any number of features, including
features for injecting fuel and/or air into a common-rail cylinder
intake and a unit that injects fuel and/or air into each cylinder
individually. For example, the injection mechanism 114 may
separately and independently control the fuel and/or air injected
into each cylinder such that each cylinder may be separately and
independently controlled to receive varying amounts of fuel and/or
air or no fuel and/or air at all. Of course, the present invention
contemplates that the injection mechanism 114 may include more or
less of these features and is not intended to be limited to the
features described above.
[0026] The system 10 may include a valve mechanism 116 for
controlling valve timing of the cylinders 18, such as to control
air flow into and exhaust flow out of the cylinders 18. The valve
mechanism 116 may be controlled by the controller 92 or other
controller and comprise any number of features, including features
for selectively and independently opening and closing cylinder
intake and/or exhaust valves. For example, the valve mechanism 116
may independently control the exhaust valve timing of each cylinder
such that the exhaust and/or intake valves may be independently
opened and closed at controllable intervals, such as with a
compression brake. Of course, the present invention contemplates
that the valve mechanism may include more or less of these features
and is not intended to be limited to the features described
above.
[0027] In operation, the controller 92 receives signals from
various engine/vehicle sensors and executes control logic embedded
in hardware and/or software to control the system 10. The computer
readable storage media may, for example, include instructions
stored thereon that are executable by the controller 92 to perform
methods of controlling all features and sub-systems in the system
10. The program instructions may be executed by the controller in
the MPU 98 to control the various systems and subsystems of the
engine and/or vehicle through the input/output ports 94. In
general, the dashed lines shown in FIG. 1 illustrate the optional
sensing and control communication between the controller and the
various components in the powertrain system. Furthermore, it is
appreciated that any number of sensors and features may be
associated with each feature in the system for monitoring and
controlling the operation thereof.
[0028] In one non-limiting aspect of the present invention, the
controller 92 may be the DDEC controller available from Detroit
Diesel Corporation, Detroit, Mich. Various other features of this
controller are described in detail in a number of U.S. patents
assigned to Detroit Diesel Corporation. Further, the controller may
include any of a number of programming and processing techniques or
strategies to control any feature in the system 10. Moreover, the
present invention contemplates that the system may include more
than one controller, such as separate controllers for controlling
system or sub-systems, including an exhaust system controller to
control exhaust gas temperatures, mass flow rates, and other
features associated therewith. In addition, these controllers may
include other controllers besides the DDEC controller described
above.
[0029] In accordance with one non-limiting aspect of the present
invention, the controller 92 or other feature, such as regeneration
system controller, may be configured for determining a desired
inlet and outlet pressure at the particulate filter to determine
whether the sensor data signals from sensors related to the
functionality of the diesel particulate filter system are accurate.
When sensors render inaccurate readings, the functionality of the
diesel particulate filter may be compromised and the operator of a
vehicle should be alerted to that situation so that corrective
action can be taken.
[0030] Turning to FIG. 2, there is represented therein a software
flow chart showing one method to perform diagnostics on an
electronically controlled diesel engine equipped with an electronic
control unit (ECU) having memory and tables resident therein; said
engine further equipped with an ignition and at least one sensor
adapted to transmit data signals from a diesel particulate filter
system having a catalyst with an inlet and an outlet; of the
present invention. While a specific method is described, it is
understood that variation and modifications of the steps recited
are included in the description of the invention as set for
therein.
[0031] Specifically, in method 118 step 120 is determining the
exhaust pressure from at least one of the diesel particulate filter
system inlet and said outlet at when said engine is at least at one
of low engine speed and low engine torque. Step 122 is determining
the exhaust pressure from at least one of the diesel particulate
inlet and said outlet when the engine is at least at one of high
engine speed and high engine torque. These determinations,
transmitted as data signals from sensors in the inlet and outlet
portions of the diesel exhaust particulate filter system are
transmitted to the ECU, where step 124 is comparing at least one of
said diesel particulate inlet and outlet pressure at low engine
speed and low engine torque with at least one of said diesel
particulate inlet and outlet pressure at high engine speed and high
engine torque with at least one of diesel particulate inlet and
outlet pressure at high engine speed and at least one of
calibratable minimum delta of diesel particulate inlet and outlet
pressure in memory in said ECU with a calibratable minimum period
of time in memory in said ECU to determine whether said sensor is
accurate. It is understood that the ECU may contain one or more
modules wherein there is reprogrammable memory resident therein
that has tables with values relating to engine speed, engine
torque, and expected inlet and outlet pressures at various engine
speeds and engine torques. When it is determined that the sensor
reading is outside the range of values in memory, there may be a
problem with either the diesel particulate filter system or the
sensors. If the engine is not in regeneration mode, and the diesel
particulate outlet pressure is below a calibratable minimum
threshold, the sensor has drifted low. If the engine is at high
speed and high torque, and the engine not in idle mode and is not
in regeneration mode, and the diesel particulate outlet pressure is
above a calibratable maximum threshold, the sensor has drifted
high. In any case, the operator of the vehicle should become aware
of the information as it is indicative of sensor drift and the need
to service the vehicle.
[0032] In step 126 when the diesel particulate inlet pressure is
measured at low engine speed, low engine torque, the time period
for the sensor readings is greater than a first calibratable soak
time when the engine is not in regeneration mode. Moreover, in step
128, when the diesel particulate inlet pressure is measured at high
engine speed high engine torque, the time period is greater than a
second calibratable soak time when the engine is not in
regeneration mode. In this regard, it is preferred that the first
calibratable soak time and said second calibratable soak time are
substantially the same.
[0033] At step 130, when a sensor is determined to be inaccurate, a
fault is set in the ECU and a maximum available engine torque is
reduced to a calibratable percentage of normally available maximum
engine torque.
[0034] In each measurement, the ECU makes a determination whether
the sensor has drifted to the high side or the low side of sensor
reading accuracy. At step 132, when the engine is at idle and is
not in diesel particulate filter regeneration mode; further
including determining whether the diesel particulate filter inlet
pressure is greater than a maximum calibratable threshold value in
memory to determine whether the diesel particulate filter sensor
has drifted high. At step 134, when the engine is in idle and is
not in diesel particulate filter regeneration mode the ECU further
determines whether the diesel particulate filter inlet pressure is
less than a lower calibratable threshold value in memory to
determine whether the diesel particulate filter sensor has drifted
low.
[0035] At step 136, a temperature reading is taken wherein at least
one said data signal is the diesel particulate filter inlet
temperature taken in a time period between when said ignition is on
to when said engine is cranking. Temperature data signals are
dependent upon engine soak histories. This step may further include
extending said time period to a calibratable time period after said
engine is cranking. In addition, it is contemplated that more than
one, and preferably three sensors are used to transmit temperature
data signals to the ECU, and when the absolute temperature
differential between any three of the data signal sensors is
greater than a calibratable threshold, a fault is logged. In this
regard, at Step 138 a determination is made as to which sensor is
out of range as compared to the other two temperature sensors and
an appropriate rationality fault is logged and an appropriate
warning indicator is activated.
[0036] Step 140 comparing the temperature of a catalyst inlet
exhaust are taken between high and low temperatures conditions when
the engine is not in regeneration mode and the time between the
high and low temperatures readings is greater than a calibratable
minimum soak time. At step 142, the catalyst inlet temperature is
determined at low engine speed and low engine torque at a minimum
first calibratable soak time and compared with the catalyst inlet
temperature at high speed and high engine torque at a minimum
second calibratable soak time. In this regard, the first
calibratable soak time and said second calibratable soak time are
different. In addition, the catalyst inlet temperatures are logged
in memory and default values are used upon each new ignition
cycle.
[0037] At step 144, the post diesel particulate filter exhaust gas
temperatures are compared between low and high temperature
conditions to determine whether a sensor has drifted. If the
temperature at low engine speed, low engine torque subtracted from
the temperature at high engine speed, high engine torque is less
than a calibratable minimum threshold, at least one temperature
sensor is stuck.
[0038] Finally, at step 146, if the engine is not operating and the
pressure difference between the diesel particulate inlet pressure
and the diesel particulate outlet pressure is greater than a
calibratable maximum threshold value, a fault is logged and a
warning indicator is activated. Generally, if an engine is not
operating, then one would expect that the pressure on the inlet
side and the outlet side of the diesel particulate filter system to
be substantially the same. However, if there is a sensor reading
that indicates that it is not the case, that reading is indicative
of sensor drift and a warning indicator could be activated to alert
the operator of the need to serve the vehicle.
[0039] The words used to describe the invention are understood to
be words of description, and not words of limitation. Those skilled
in the art recognize that many variations and medications are
possible upon a reading of the specification without departing from
the scope and spirit of the invention as set forth in the appended
claims.
* * * * *