Title of Invention	A POST-OXYGEN PERFORMANCE DIAGNOSIS SYSTEM AND METHOD TO RESTRICT EXHAUST EMISSION IN A VEHICLE
Abstract	The invention relates to a system (10, 16) comprising a post oxygen performance diagnostic (POPD) module (52) that performs a POPD of a post oxygen sensor(26), wherein said POPD (52) comprises a deceleration fuel cutoff (DFCO) portion; and a torque converter control module (54) that adjusts operation of a torque converter clutch (TCC) (44) wherein said POPD module (52) and said torque converter control module (54) operate said TCC (44) to control engine speed above a predetermined engine speed during said DFCO portion of said POPD (52)

Title of Invention

A POST-OXYGEN PERFORMANCE DIAGNOSIS SYSTEM AND METHOD TO RESTRICT EXHAUST EMISSION IN A VEHICLE

Abstract

The invention relates to a system (10, 16) comprising a post oxygen performance diagnostic (POPD) module (52) that performs a POPD of a post oxygen sensor(26), wherein said POPD (52) comprises a deceleration fuel cutoff (DFCO) portion; and a torque converter control module (54) that adjusts operation of a torque converter clutch (TCC) (44) wherein said POPD module (52) and said torque converter control module (54) operate said TCC (44) to control engine speed above a predetermined engine speed during said DFCO portion of said POPD (52)

Full Text	CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U S Provisional Application No 60/984,592, filed on Nov 1, 2007 The disclosure of the above application is incorporated herein by reference in its entirety FIELD OF THE INVENTION The present disclosure relates to vehicles including a post oxygen performance diagnostic system BACKGROUND OF THE INVENTION The statements in this section merely provide background information related to the present disclosure and may not constitute prior art. During the combustion process, gasoline is oxidized and hydrogen (H) and carbon (C) combine with air Various chemical compounds are formed including carbon dioxide (CO2), water (H2O), carbon monoxide (CO), nitrogen oxides (NOx),unbumed hydrocarbons (HC), sulfur oxides (SO2), and other compounds Automobile exhaust systems include a catalytic converter that reduces exhaust emissions by chemically converting the exhaust gas into carbon dioxide (CO2), nitrogen (N), and water (H2O). Exhaust gas oxygen sensors generate signals indicating the oxygen content of the exhaust gas An inlet or Indicating the oxygen content of the exhaust gas An inlet or pre-catalyst oxygen sensor monitors the oxygen level associated with the inlet exhaust stream of the catalytic converter. This inlet O2 sensor is also the primary feedback mechanism that maintains the air-to-fuel (A/F) ratio of the engine at the chemically correct or stoichiometric A/F ratio that is needed to support the catalytic conversion processes. An outlet or post-catalyst oxygen sensor monitors the oxygen level associated with an outlet exhaust stream of the catalytic converter. The post-02 sensor signal is used for secondary A/F ratio control Engine diagnostic systems require properly functioning oxygen sensors Therefore, the oxygen sensors are periodically checked to ensure proper function Traditionally, the diagnostic systems employ intrusive checks to check the operation of the sensors. During the intrusive checks, the A/F ratio may be manipulated and the sensor response is monitored. However, these intrusive checks may increase exhaust emissions and/or cause engine instability and reduced drivability that may be noticeable to a vehicle operator During some operating conditions, an engine control system may cutoff fuel to the engine during deceleration. This technique is often referred to as deceleration fuel cutoff (DFCO) Some diagnostic systems evaluate operation of the post-catalyst oxygen sensor during DFCO DE 97222334 discloses an exhaust gas probe diagnosis method for Internal combustion engine. According to the invention, the probe is arranged downstream of a catalyst converter, and is sensitive to one or more exhaust constituents. The rate at which the signal from the probe reacts when the concentration of the constituent is changed, is used as a judgement criterion for diagnosing the probe performance. The probe may be an oxygen-sensitive probe with Nernst characteristics. The reaction of the probe to changes in the oxygen content of the exhaust gas is evaluated after the start of shifting phase with fuel switch-off. Faults in the probe are displayed or stored. US 2002/0134596 discloses a controller of a hybrid vehicle. According to the invention, in fuel cut control during vehicle deceleration at an engine side, a return engine speed is set at a speed in which the engine inevitably stalls. However, at motor side, assist-control is executed such that engine speed is maintained so that engine stall does not occur, and so that engine speed smoothly converges at an idle speed. Thus, the engine speed is set at a lower value, so that fuel cut is executed as long as possible to improve fuel consumption. OBJECT OF THE INVENTION It is therefore an object of the invention to propose a post oxygen performance diagnostic system and method to restrict exhaust emission and increase engine stability and drivability to a vehicle operator. SUMMARY OF THE INVENTION A system comprises a post oxygen performance diagnostic (POPD) module that performs a POPD of a post oxygen sensor, wherein the POPD includes a deceleration fuel cutoff (DFCO) portion A torque converter control module adjusts operation of a torque converter clutch (TCC). The POPD module and the torque converter control module operate the TCC to control engine speed above a predetermined engine speed during the DFCO portion of the POPD A method comprises performing a POPD of a post oxygen sensor, wherein the POPD includes a deceleration fuel cutoff (DFCO) portion, and adjusting operation of a torque converter clutch (TCC) to control engine speed above a predetermined engine speed during the DFCO portion of the POPD Further areas of applicability will become apparent from the description provided herein It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way FIG. 1 is a functional block diagram of an engine control system according to the present disclosure, and FIG 2 is a flowchart illustrating exemplary operation of the control module of FIG 1 DETAILED DESCRIPTION OF THE INVENTION The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features As used herein, the term module refers to an application specific integrated circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group) and memory that execute one or more software or firmware programs, a combinational logic circuit, and/or other suitable components that provide the described functionality. Referring now to FIG 1, an engine system 10 includes an engine 12, an exhaust system 14 and a control module 16 Air is drawn into the engine 12 through a throttle 17 and an intake manifold 18, and is mixed with fuel in the engine 12 The air and fuel mixture is combusted within cylinders (not shown) to generate drive torque The gases produced via combustion exit the engine through an exhaust manifold 19 and the exhaust system 14. The exhaust system 14 includes a catalytic converter 22, a pre- catalyst or inlet oxygen sensor 24, hereinafter pre-O2 sensor 24 and a post-catalyst oxygen sensor 26, herein after post-02 sensor 26 The exhaust gases are treated within the catalytic converter 22 and are exhausted to atmosphere The pre-02 sensor 24 and the post-02 sensor 26 generate respective signals that are communicated to the control module 16 The pre-02 and post-02 sensor signals indicate the oxygen content of the exhaust entering and exiting the catalytic converter 22, respectively The control module 16 communicates with a fuel system to regulate fuel flow to the engine 12 based on the sensor signals An output of the engine 12 is input to a torque converter (TC) 40 having a torque converter clutch (TCC) 44. An output of the TC 40 is input to a transmission 50 The control module 16 may include a post oxygen performance diagnostic (POPD) module 52 that performs a POPD The POPD may include a deceleration fuel cutoff (DFCO) portion The control module 16 may also include a torque converter control module 54 that controls operation of a torque converter clutch (TCC) As can be appreciated, the engine system 10 may include a wide variety of sensors that provide inputs to the control module 16 Furthermore, one or more accessories, actuators or other devices may receive control signals from the control module 16 Furthermore, the control module 16 may be implemented using an engine control module, an engine control module and a transmission control module, or using other arrangements The control module 16 may optionally perform electronic throttle control Still other variations are contemplated The present disclosure allows the engine system 10 to maintain engine speed during a deceleration fuel cutoff (DFCO) portion of a post oxygen performance diagnostic (POPD) system During DFCO, some vehicles release the TCC 44. Without engine braking, the engine speed will quickly decrease to idle speed. As a result of the reduced engine speed, the control module 16 may disable the POPD system before completion due to the reduced engine speed For example, the POPD system may require engine speeds greater than 800 revolutions per minute (RPM) The engine system 10 according to the present disclosure maintains the TCC 44 in a controlled slip state or a lock state during DFCO, which causes the engine 12 to be in an engine braking condition As a result of the engine braking, the engine 12 will have a higher engine speed during DFCO Therefore, the control module 16 will be able to complete the POPD during DFCO The TCC Module 44 decides the appropriate action (lock state, controlled slip state or ignore POPD request) based on ability for POPD to complete, dnveability and transmission hardware limitations One means by which the TCC control can respond to the POPD assistance request, is to maintain powertrain dnvehne coupling, by locking the TCC or maintaining the TCC in a controlled slip condition As can be appreciated, the dynamics that are involved are different for each transmission design, and hence some development work may be required to determine the specific actions for each application. The control module may honor the request except when this would conflict with hardware protection and/or durability, transmission diagnostic actions, torque security actions, engine stalling concerns, minimum transmission pump speed criteria or otherwise cause customer dissatisfaction due to noise, vibration and harshness (NVH) problems. Still other criteria may be used. While the engine speed may stay high enough during DFCO to complete the POPD when the vehicle is travelling greater than 55 mph, test vehicles do not typically travel at this speed during current emissions testing procedures. As a result, the POPD test may not complete during emissions testing, which may pose problems for certification. The control module 16 commands the TCC 44 to either a locked state or a controlled slip state to maintain the engine speed and prevent a rapid decrease in engine speed during a DFCO portion of the POPD test As a result, the engine 12 remains mechanically linked to the drive wheels allowing the momentum of the vehicle to maintain a higher engine speed, which allows more time/airflow to complete the*POPD diagnostic The POPD test was developed to meet the requirements for emissions systems using the post-02 sensor 26 for diagnosis of the catalytic converter 22 Vehicles using this approach need to test the post O2 26 Furthermore, the diagnostic system may also measure the performance of the post-02 sensor 26 in a forced rich condition and a lean condition The POPD test may be enabled when the engine is in proper conditions for a DFCO Further operating conditions include a minimum engine speed, minimum vehicle speed, and/or other conditions If the monitored conditions fall outside under these conditions, the POPD will disable and abort the test When the POPD test is enabled, the POPD test may command the engine control system to a DFCO inhibit state for a predetermined period This prevents normal DFCO from occurring before the POPD is ready for the DFCO portion of the POPD test At the start of the predetermined period, the control module may command the TCC 44 into a fully locked state In the fully locked state, the engine 12 is fully coupled to the transmission 50 The TCC 44 remains in the fully locked state for a sufficient amount of time to allow the POPD test to complete or the DFCO portion of the POPD test to complete Alternately, the control module commands a controlled slip of the TCC 44 at the start of the predetermined period instead of fully locking the TCC 44 The controlled TCC slip allows the engine speed to be elevated over an increased window of operation to allow the POPD test a sufficient amount of time to complete or the DFCO portion of the POPD test to complete Alternately, if TCC control features are not available (driveability concerns and/or transmission hardware limitations), the TCC control actions related to the POPD request may be ignored The POPD will then continue to send the request until it completes the DFCO portion of the POPD test Once the DFCO is complete, the POPD ends the TCC request mode From this point, the POPD test does not depend upon engine speed or vehicle speed Engine speed will decrease more slowly during the DFCO portion of the POPD test as a result of the present disclosure For example, the engine speed may decrease less during the DFCO portion of the POPD test with the TCC 44 at full lock as compared to normal control. In other words, without using the control of the present invention, the engine speed may decelerate to a disable speed condition such as 800 RPM before completing the DFCO portion of the POPD test. Referring now to FIG 2, steps of a method for controlling the TCC during the DFCO portion of the POPD test are shown Control begins with step 100 and continues with step 104 If step 104 is true, control continues with step 104 and determines whether the POPD test has been initiated In step 108, control temporarily inhibits DFCO. In step 111, control determines whether TCC control features are available (for example only, the features may be temporarily or permanently unavailable due to dnveability concerns and/or transmission hardware limitations) If step 111 is false, the POPD will then continue with step 113 and attempt to perform the DFCO portion of the POPD test If the test completes as determined in step 114, control ends in step- 124 However, completion is less likely in this mode for reasons described above. If step 111 is true and the TCC control features are available, control continues with step 112. In step 112, control commands the TCC 44 to a locked state or a partial slip state or disables control of the TCC 44 In step 116, control performs the DFCO portion of the POPD test In step 120, control ends the locked state when the DFCO portion is done At this point, control finishes the POPD test and control ends in step 124 WE CLAIM : 1 System (1O) comprising an internal combustion engine (12) a module (52) for diagnosing the function of an oxygen sensor (POPD) (26 disposed downstream a catalyst (22) that performs the function of a (POPD), wherein the (POPD) comprises a overrun cut-off (DFCO) section, characterized by a torque- converter control module (54), which matches the operation f a torque converter coupling (44), wherein said POPD module (52) and the torque- converter control module (54) operate the torque converter coupling (44) to control the engine speed over the (DFCO) section of (POPD) above a predetermined IC engine speed 2 System as claimed in claim 1, wherein the (POPD) module (52) and the torque- converter control module (54) dictate the torque converter coupling (44) before performing the (DFCO) section of (POPD) to a force-fitting state 3 System as claimed in claim 1, wherein the (POPD) module (52) and the torque-converter control module (54) dictate the torque converter coupling (44) before executing the (DFCO) section of (POPD) to a slip condition 4 System as claimed in claim 1, wherein the (POPD) module (52) deactivates the torque- converter control module (54) before executing the (DFCO) section of (POPD) 5 System as claimed in claim 2, wherein the (POPD) module (52) and the torque-converter control module (54) after closing the (DFCO) section of (POPD) releases the torque converter coupling (44) from the force-fitting condition. 6 System as claimed in claim 3, wherein the POPD) module (52 and the torque converter control module (54) after closing the (DFCO) section of (POPD) releases the torque converter coupling (44) from the slip condition 7 System as claimed in claim 4, wherein the (POPD) module (52) activates the torque-converter control module (54) after closing the (DFCO) section of (POPD) 8 System as claimed in claim 1, comprising a control module (16) containing the (POPD) module (52)and the torque-converter control module (54) 9 System as claimed In claim 1, comprising the torque converter coupling (44) and the tailing oxygen sensor (26) ABSTRACT TITLE : 'A POST-OXYGEN PERFORMANCE DIAGNOSIS SYSTEM AND METHOD TO RESTRICT EXHAUST EMISSION IN A VEHICLE' The invention relates to a system (10, 16) comprising a post oxygen performance diagnostic (POPD) module (52) that performs a POPD of a post oxygen sensor(26), wherein said POPD (52) comprises a deceleration fuel cutoff (DFCO) portion; and a torque converter control module (54) that adjusts operation of a torque converter clutch (TCC) (44) wherein said POPD module (52) and said torque converter control module (54) operate said TCC (44) to control engine speed above a predetermined engine speed during said DFCO portion of said POPD (52)

Full Text

CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of U S Provisional Application No 60/984,592, filed
on Nov 1, 2007 The disclosure of the above application is incorporated herein by
reference in its entirety
FIELD OF THE INVENTION
The present disclosure relates to vehicles including a post oxygen performance
diagnostic system
BACKGROUND OF THE INVENTION
The statements in this section merely provide background information related to the
present disclosure and may not constitute prior art.
During the combustion process, gasoline is oxidized and hydrogen (H) and carbon (C)
combine with air Various chemical compounds are formed including carbon dioxide
(CO2), water (H2O), carbon monoxide (CO), nitrogen oxides (NOx),unbumed
hydrocarbons (HC), sulfur oxides (SO2), and other compounds
Automobile exhaust systems include a catalytic converter that reduces exhaust
emissions by chemically converting the exhaust gas into carbon dioxide (CO2),
nitrogen (N), and water (H2O). Exhaust gas oxygen sensors generate signals
indicating the oxygen content of the exhaust gas An inlet or

Indicating the oxygen content of the exhaust gas An inlet or pre-catalyst oxygen
sensor monitors the oxygen level associated with the inlet exhaust stream of the
catalytic converter. This inlet O2 sensor is also the primary feedback mechanism that
maintains the air-to-fuel (A/F) ratio of the engine at the chemically correct or
stoichiometric A/F ratio that is needed to support the catalytic conversion processes.
An outlet or post-catalyst oxygen sensor monitors the oxygen level associated with an
outlet exhaust stream of the catalytic converter. The post-02 sensor signal is used for
secondary A/F ratio control
Engine diagnostic systems require properly functioning oxygen sensors Therefore,
the oxygen sensors are periodically checked to ensure proper function Traditionally,
the diagnostic systems employ intrusive checks to check the operation of the sensors.
During the intrusive checks, the A/F ratio may be manipulated and the sensor
response is monitored. However, these intrusive checks may increase exhaust
emissions and/or cause engine instability and reduced drivability that may be
noticeable to a vehicle operator
During some operating conditions, an engine control system may cutoff fuel to the
engine during deceleration. This technique is often referred to as deceleration fuel
cutoff (DFCO) Some diagnostic systems evaluate operation of the post-catalyst
oxygen sensor during DFCO
DE 97222334 discloses an exhaust gas probe diagnosis method for Internal
combustion engine. According to the invention, the probe is arranged downstream of
a catalyst converter, and is sensitive to one or more exhaust constituents. The rate at
which the signal from the probe reacts when the concentration of the constituent is
changed, is used as a judgement criterion for diagnosing the probe performance. The

probe may be an oxygen-sensitive probe with Nernst characteristics. The reaction of
the probe to changes in the oxygen content of the exhaust gas is evaluated after the
start of shifting phase with fuel switch-off. Faults in the probe are displayed or stored.
US 2002/0134596 discloses a controller of a hybrid vehicle. According to the
invention, in fuel cut control during vehicle deceleration at an engine side, a return
engine speed is set at a speed in which the engine inevitably stalls. However, at
motor side, assist-control is executed such that engine speed is maintained so that
engine stall does not occur, and so that engine speed smoothly converges at an idle
speed. Thus, the engine speed is set at a lower value, so that fuel cut is executed as
long as possible to improve fuel consumption.
OBJECT OF THE INVENTION
It is therefore an object of the invention to propose a post oxygen performance
diagnostic system and method to restrict exhaust emission and increase engine
stability and drivability to a vehicle operator.

SUMMARY OF THE INVENTION
A system comprises a post oxygen performance diagnostic (POPD) module that
performs a POPD of a post oxygen sensor, wherein the POPD includes a deceleration
fuel cutoff (DFCO) portion A torque converter control module adjusts operation of a
torque converter clutch (TCC). The POPD module and the torque converter control
module operate the TCC to control engine speed above a predetermined engine
speed during the DFCO portion of the POPD
A method comprises performing a POPD of a post oxygen sensor, wherein the POPD
includes a deceleration fuel cutoff (DFCO) portion, and adjusting operation of a torque
converter clutch (TCC) to control engine speed above a predetermined engine speed
during the DFCO portion of the POPD
Further areas of applicability will become apparent from the description provided
herein It should be understood that the description and specific examples are
intended for purposes of illustration only and are not intended to limit the scope of the
present disclosure.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The drawings described herein are for illustration purposes only and are not intended
to limit the scope of the present disclosure in any way
FIG. 1 is a functional block diagram of an engine control system according to the
present disclosure, and
FIG 2 is a flowchart illustrating exemplary operation of the control module of FIG 1

DETAILED DESCRIPTION OF THE INVENTION
The following description is merely exemplary in nature and is not intended to limit the
present disclosure, application, or uses It should be understood that throughout the
drawings, corresponding reference numerals indicate like or corresponding parts and
features
As used herein, the term module refers to an application specific integrated circuit
(ASIC), an electronic circuit, a processor (shared, dedicated, or group) and memory
that execute one or more software or firmware programs, a combinational logic circuit,
and/or other suitable components that provide the described functionality.
Referring now to FIG 1, an engine system 10 includes an engine 12, an exhaust
system 14 and a control module 16 Air is drawn into the engine 12 through a throttle
17 and an intake manifold 18, and is mixed with fuel in the engine 12 The air and fuel
mixture is combusted within cylinders (not shown) to generate drive torque The gases
produced via combustion exit the engine through an exhaust manifold 19 and the
exhaust system 14. The exhaust system 14 includes a catalytic converter 22, a pre-
catalyst or inlet oxygen sensor 24, hereinafter pre-O2 sensor 24 and a post-catalyst
oxygen sensor 26, herein after post-02 sensor 26 The exhaust gases are treated
within the catalytic converter 22 and are exhausted to atmosphere
The pre-02 sensor 24 and the post-02 sensor 26 generate respective signals that are
communicated to the control module 16 The pre-02 and post-02 sensor signals

indicate the oxygen content of the exhaust entering and exiting the catalytic converter
22, respectively The control module 16 communicates with a fuel system to regulate
fuel flow to the engine 12 based on the sensor signals An output of the engine 12 is
input to a torque converter (TC) 40 having a torque converter clutch (TCC) 44. An
output of the TC 40 is input to a transmission 50
The control module 16 may include a post oxygen performance diagnostic (POPD)
module 52 that performs a POPD The POPD may include a deceleration fuel cutoff
(DFCO) portion The control module 16 may also include a torque converter control
module 54 that controls operation of a torque converter clutch (TCC)
As can be appreciated, the engine system 10 may include a wide variety of sensors
that provide inputs to the control module 16 Furthermore, one or more accessories,
actuators or other devices may receive control signals from the control module 16
Furthermore, the control module 16 may be implemented using an engine control
module, an engine control module and a transmission control module, or using other
arrangements The control module 16 may optionally perform electronic throttle
control Still other variations are contemplated
The present disclosure allows the engine system 10 to maintain engine speed during
a deceleration fuel cutoff (DFCO) portion of a post oxygen performance diagnostic
(POPD) system During DFCO, some vehicles release the TCC 44. Without engine
braking, the engine speed will quickly decrease to idle speed. As a result of the
reduced engine speed, the control module 16 may disable the POPD system before
completion due to the reduced engine speed For example, the POPD system may
require engine speeds greater than 800 revolutions per minute (RPM)

The engine system 10 according to the present disclosure maintains the TCC 44 in a
controlled slip state or a lock state during DFCO, which causes the engine 12 to be in
an engine braking condition As a result of the engine braking, the engine 12 will have
a higher engine speed during DFCO Therefore, the control module 16 will be able to
complete the POPD during DFCO The TCC Module 44 decides the appropriate action
(lock state, controlled slip state or ignore POPD request) based on ability for POPD to
complete, dnveability and transmission hardware limitations One means by which the
TCC control can respond to the POPD assistance request, is to maintain powertrain
dnvehne coupling, by locking the TCC or maintaining the TCC in a controlled slip
condition
As can be appreciated, the dynamics that are involved are different for each
transmission design, and hence some development work may be required to
determine the specific actions for each application. The control module may honor the
request except when this would conflict with hardware protection and/or durability,
transmission diagnostic actions, torque security actions, engine stalling concerns,
minimum transmission pump speed criteria or otherwise cause customer
dissatisfaction due to noise, vibration and harshness (NVH) problems. Still other
criteria may be used.
While the engine speed may stay high enough during DFCO to complete the POPD
when the vehicle is travelling greater than 55 mph, test vehicles do not typically travel
at this speed during current emissions testing procedures. As a result, the POPD test
may not complete during emissions testing, which may pose problems for certification.

The control module 16 commands the TCC 44 to either a locked state or a controlled
slip state to maintain the engine speed and prevent a rapid decrease in engine speed
during a DFCO portion of the POPD test As a result, the engine 12 remains
mechanically linked to the drive wheels allowing the momentum of the vehicle to
maintain a higher engine speed, which allows more time/airflow to complete the*POPD
diagnostic
The POPD test was developed to meet the requirements for emissions systems using
the post-02 sensor 26 for diagnosis of the catalytic converter 22 Vehicles using this
approach need to test the post O2 26 Furthermore, the diagnostic system may also
measure the performance of the post-02 sensor 26 in a forced rich condition and a
lean condition
The POPD test may be enabled when the engine is in proper conditions for a DFCO
Further operating conditions include a minimum engine speed, minimum vehicle
speed, and/or other conditions If the monitored conditions fall outside under these
conditions, the POPD will disable and abort the test
When the POPD test is enabled, the POPD test may command the engine control
system to a DFCO inhibit state for a predetermined period This prevents normal
DFCO from occurring before the POPD is ready for the DFCO portion of the POPD
test At the start of the predetermined period, the control module may command the
TCC 44 into a fully locked state In the fully locked state, the engine 12 is fully coupled
to the transmission 50 The TCC 44 remains in the fully locked state for a sufficient
amount of time to allow the POPD test to complete or the DFCO portion of the POPD
test to complete

Alternately, the control module commands a controlled slip of the TCC 44 at the start
of the predetermined period instead of fully locking the TCC 44 The controlled TCC
slip allows the engine speed to be elevated over an increased window of operation to
allow the POPD test a sufficient amount of time to complete or the DFCO portion of
the POPD test to complete
Alternately, if TCC control features are not available (driveability concerns and/or
transmission hardware limitations), the TCC control actions related to the POPD
request may be ignored The POPD will then continue to send the request until it
completes the DFCO portion of the POPD test Once the DFCO is complete, the
POPD ends the TCC request mode From this point, the POPD test does not depend
upon engine speed or vehicle speed
Engine speed will decrease more slowly during the DFCO portion of the POPD test as
a result of the present disclosure For example, the engine speed may decrease less
during the DFCO portion of the POPD test with the TCC 44 at full lock as compared to
normal control. In other words, without using the control of the present invention, the
engine speed may decelerate to a disable speed condition such as 800 RPM before
completing the DFCO portion of the POPD test.
Referring now to FIG 2, steps of a method for controlling the TCC during the DFCO
portion of the POPD test are shown Control begins with step 100 and continues with
step 104 If step 104 is true, control continues with step 104 and determines whether
the POPD test has been initiated In step 108, control temporarily inhibits DFCO. In
step 111, control determines whether TCC control features are available (for example

only, the features may be temporarily or permanently unavailable due to dnveability
concerns and/or transmission hardware limitations) If step 111 is false, the POPD will
then continue with step 113 and attempt to perform the DFCO portion of the POPD
test If the test completes as determined in step 114, control ends in step- 124
However, completion is less likely in this mode for reasons described above.
If step 111 is true and the TCC control features are available, control continues with
step 112. In step 112, control commands the TCC 44 to a locked state or a partial slip
state or disables control of the TCC 44 In step 116, control performs the DFCO portion
of the POPD test In step 120, control ends the locked state when the DFCO portion is
done At this point, control finishes the POPD test and control ends in step 124

WE CLAIM :
1 System (1O) comprising an internal combustion engine (12) a module (52) for
diagnosing the function of an oxygen sensor (POPD) (26 disposed downstream
a catalyst (22) that performs the function of a (POPD), wherein the (POPD)
comprises a overrun cut-off (DFCO) section, characterized by a torque-
converter control module (54), which matches the operation f a torque
converter coupling (44), wherein said POPD module (52) and the torque-
converter control module (54) operate the torque converter coupling (44) to
control the engine speed over the (DFCO) section of (POPD) above a
predetermined IC engine speed
2 System as claimed in claim 1, wherein the (POPD) module (52) and the torque-
converter control module (54) dictate the torque converter coupling (44) before
performing the (DFCO) section of (POPD) to a force-fitting state
3 System as claimed in claim 1, wherein the (POPD) module (52) and the
torque-converter control module (54) dictate the torque converter coupling (44)
before executing the (DFCO) section of (POPD) to a slip condition
4 System as claimed in claim 1, wherein the (POPD) module (52)
deactivates the torque- converter control module (54) before executing the
(DFCO) section of (POPD)
5 System as claimed in claim 2, wherein the (POPD) module (52) and the
torque-converter control module (54) after closing the (DFCO) section of
(POPD) releases the torque converter coupling (44) from the force-fitting
condition.

6 System as claimed in claim 3, wherein the POPD) module (52 and the torque
converter control module (54) after closing the (DFCO) section of (POPD)
releases the torque converter coupling (44) from the slip condition
7 System as claimed in claim 4, wherein the (POPD) module (52) activates the
torque-converter control module (54) after closing the (DFCO) section of
(POPD)
8 System as claimed in claim 1, comprising a control module (16) containing the
(POPD) module (52)and the torque-converter control module (54)
9 System as claimed In claim 1, comprising the torque converter coupling (44) and
the tailing oxygen sensor (26)

ABSTRACT

TITLE : 'A POST-OXYGEN PERFORMANCE DIAGNOSIS SYSTEM AND
METHOD TO RESTRICT EXHAUST EMISSION IN A VEHICLE'
The invention relates to a system (10, 16) comprising a post oxygen performance
diagnostic (POPD) module (52) that performs a POPD of a post oxygen sensor(26),
wherein said POPD (52) comprises a deceleration fuel cutoff (DFCO) portion; and a
torque converter control module (54) that adjusts operation of a torque converter
clutch (TCC) (44) wherein said POPD module (52) and said torque converter control
module (54) operate said TCC (44) to control engine speed above a predetermined
engine speed during said DFCO portion of said POPD (52)

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Patent Number

271749

Indian Patent Application Number

1848/KOL/2008

PG Journal Number

10/2016

Publication Date

04-Mar-2016

Grant Date

02-Mar-2016

Date of Filing

30-Oct-2008

Name of Patentee

GM GLOBAL TECHNOLOGY OPERATIONS,INC

Applicant Address

300 GM RENAISSANCE CENTER, DETROIT, MICHIGAN 48265-3000

Inventors:

#	Inventor's Name	Inventor's Address
1	IGOR ANILOVICH	105 CHESTNUT RIDGE, WALLED LAKE, MICHIGAN 48390
2	DOUGLAS J. MOENING	24181 BROADVIEW STREET, FARMINGTON, MICHIGAN 48336
3	JOHN W. SIEKKINEN	43509 CASTLEWOOD NOVI, MICHIGAN 48375
4	DANIEL J. WICKMAN	526 HARTSOUGH STREET PLYMOUTH, MICHIGAN 48170
5	JAYSON S. SCHWALM	25245 ARDEN PARK DRIVE, FARMINGTON HILLS, MICHIGAN 48336

PCT International Classification Number

F16H59/14; F16H61/14;B60W30/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	60/984592	2007-11-01	U.S.A.