Title of Invention	A FUEL EFFICIENCY ESTIMATION SYSTEM AND A METHOD FOR DETERMINING A FUEL EFFICIENCY OF AN INTERNAL COMBUSTION SYSTEM
Abstract	The invention relates to a fuel efficiency estimation system for determining a fuel efficiency of an internal combustion engine (12) comprising a first module (50) that determines a current iterative intake air mass value provided to said engine (12) and compares said current iterative intake air mass value to a previous iterative intake air mass value, said first module (50) providing said current iterative intake air mass value as a final intake air mass value when a difference between said current iterative intake air mass value and said previous iterative intake air mass value is less than a predetermined threshold value;a second module (52) that determines a fuel mass rate value based on said final air intake mass value; and a third module (50) that determines a power loss for the internal combustion engine (12) based on said fuel mass rate value, wherein a fuel efficiency of the engine (12) is determined based on said power loss.

Title of Invention

A FUEL EFFICIENCY ESTIMATION SYSTEM AND A METHOD FOR DETERMINING A FUEL EFFICIENCY OF AN INTERNAL COMBUSTION SYSTEM

Abstract

The invention relates to a fuel efficiency estimation system for determining a fuel efficiency of an internal combustion engine (12) comprising a first module (50) that determines a current iterative intake air mass value provided to said engine (12) and compares said current iterative intake air mass value to a previous iterative intake air mass value, said first module (50) providing said current iterative intake air mass value as a final intake air mass value when a difference between said current iterative intake air mass value and said previous iterative intake air mass value is less than a predetermined threshold value;a second module (52) that determines a fuel mass rate value based on said final air intake mass value; and a third module (50) that determines a power loss for the internal combustion engine (12) based on said fuel mass rate value, wherein a fuel efficiency of the engine (12) is determined based on said power loss.

Full Text	CROSS REFERENCE TO RELATED APPLICATIONS The application claims the benefit of US Provisional Application No.60/755,001 filed on December 29, 2005. The disclosure of the above application is incorporated herein by reference. FIELD OF THE INVENTION The present disclosure relates to engine control systems, and more particularly to an engine control system that determines a fuel efficiency of an internal combustion based on a power loss of the engine. BACKGROUND OF THE INVENTION Vehicles include an internal combustion engine that generates drive torque. More Particularly, the engine draws in air and mixes the air with fuel to form a combustion mixture. The combustion mixture is compressed within cylinders and is combusted to drive pistons that are disposed within the cylinders. The pistons drive a crankshaft that transfers drive torque to a transmission and a drivetrain. Vehicle manufacturers typically use a dynamometer to evaluate vehicle performance. For example, a dynamometer may determine optimal engine torque output for a range of engine speeds. However, actual torque output may be different than the optimal torque output generated by the vehicle in controlled conditions. More specifically, the actual torque output may be affected by external conditions including, but not limited to air temperature himidity and/or barometric pressure. The document D1 discloses: A preferred input torque for a hybrid power train is determined within a solution space of feasible input torques in accordance with a plurality of powertrain system constraints that results in a minimum overall powertrain system loss. System power losses and battery utilization costs system loss is converged upon to determine the preferred input torque. The document D2 discloses:. A two-mode, compound-split, electro-mechanical transmission utilizes an input member for receiving power from an engine, and an output member for delivering power from the transmission. First and second motor/generators are operatively connected to an energy storage device through a control for interchanging electrical power among the storage device, the first motor/generator and the second motor/generator. The transmission employs three planetary gear sets. Each planetary gear arrangement utilizes first, second and third gear members. At least one of the gear members in the first or second planetary gear sets is connected to the first motor/generator. One of the gear members of the first or second planetary gear sets is continuously connected to one of the gear members in the third planetary gear set. Another gear member of the first or second planetary gear set is operatively connected to the input member, and one gear member of the third planetary gear set is selectively connected to ground. A lock-up clutch selectively locks two of the planetary gear sets in a 1:1 ratio. SUMMARY OF THE INVENTION The present disclosure provides a fuel efficiency estimation system for determining a fuel efficiency of an internal combustion engine. The system includes a first module that determines a final air intake value and a second module that determines a fuel mass rate value based on the final air intake value. A third module determines the power loss for the internal combustion engine based on the fuel mass rate value. A fuel efficiency of the engine is determined based on the power loss. In other features, the first module includes a first sub-module that generates an initial air intake value based on at least one of an engine speed value, an engine torque value and an engine coolant temperature value. The first module further includes a second sub-module that outputs a current iterative air intake value based on at least one of the engine speed value, the engine torque value and the coolant temperature value. In other features, the first module further includes a third sub-module that determines a spark advance value, a fourth sub-module that determines an intake and exhaust cam phaser position value and a fifth sub-module that determines an air/fuel ratio. The spark advance value, the intake and exhaust cam phaser positions values and the air/fuel ratio are calculated based on the current iterative air intake value, the engine speed value and the coolant temperature value. In still other features, the second sub-module calculates the current iterative air intake value based on the spark advance value, the intake and exhaust cam phaser position values and the air/fuel ratio value. In yet other features, the second sub-module determines a difference between the current iterative air intake value and a prior iterative air intake value. The second sub-module outputs a final iterative air intake value when the difference is less than a predetermined threshold value. The second sub-module updates the iterative air intake value when the difference is greater than the predetermined threshold value. Further areas of applicability will become apparent from the description provided herein. It should be under. 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 present disclosure will become more fully understood from the detailed description and the accompanying drawings, wherein Figure 1 is a functional block diagram of an engine system. Figure 2 is an exemplary block diagram of a control module that calculates a fuel efficiency of the engine system according to he present disclosure. Figure 3 is an exemplary block diagram of an air intake calculation module according to the present disclosure, and Figure 4 is a flowchart illustrating exemplary steps executed by the fuel efficiency control according to the present disclosure. DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS The following description is merely exemplary in nature and is in no way intended to limit the disclosure, its application, or uses. As used herein, the term module or device refers to an application specific integrated circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group) and memory that executes one or more software or firmware programs, a combinational logic circuit and/or other suitable components that provides the described functionality. According to the present disclosure, a fuel efficiency of an engine is calculated as a function of a power loss of the engine, which is based on the difference between an optimal power output value and an estimated power output value. More specifically, the estimated power is calculated during a stable or steady state engine condition based on current engine speed, engine torque and coolant temperature values. Referring now to figure 1, an engine system 10 includes an engine 12 that- combusts an air/fuel mixture to produce drive torque. Air is drawn into an intake manifold 14 through a throttle 16. The throttle 16 regulates air flow into the intake manifold 14. The air is mixed with fuel and is combusted within cylinders 18 to produce drive torque Although four cylinders are illustrated, it can be appreciated that the engine 12 may include additional or fewer cylinders 18 For example, engines having 2, 3, 5, 6, 8, 10 and 12 cylinders are contemplated [0019] A fuel injector (not shown) injects fuel that is combined with air to form an air/fuel mixture that is combusted within the cylinder 18 A fuel injection system 20 regulates the fuel injector to provide a desired air-to-fuel ratio within each cylinder 18 An intake valve 22 selectively opens and closes to enable the air/fuel mixture to enter the cylinder 18 The position of the intake valve is regulated by an intake cam shaft 24 A piston (not shown) compresses the air/fuel mixture within the cylinder 18 After the combustion event, an exhaust valve 28 selectively opens and closes to enable the exhaust gases to exit the cylinder 18 The position of the exhaust valve is regulated by an exhaust cam shaft 30 The piston drives a crankshaft (not shown) to produce drive torque The crankshaft rotatably drives camshafts 24,30 using a timing chain (not shown) to regulate the timing of intake and exhaust valves 22, 28 Although dual camshafts are shown, a single camshaft may be used [0020] The engine 12 may include an intake cam phaser 32 and/or an exhaust cam phaser 34 that respectively regulate rotational timing of the intake and exhaust cam shafts 24, 30 relative to a rotational position of the crankshaft More specifically, a phase angle of the intake and exhaust cam phasers 32, 34 may be retarded or advanced to regulate the rotational timing of the intake and exhaust cam shafts 24, 30 [0021] A coolant temperature sensor 36 is responsive to the temperature of a coolant circulating through the engine 12 and generates a coolant temperature signal 37 A barometric pressure sensor 38 is responsive to atmospheric pressure and generates a barometric pressure signal 39 An engine speed sensor 42 is responsive to the engine speed and outputs an engine speed signal 43 A temperature sensor 44 is responsive to ambient temperature and outputs a temperature signal 45 An oil temperature sensor 46 is responsive to oil temperature and outputs an oil temperature signal 47 A control module 49 regulates operation of the engine system 10 based on the various sensor signals The engine control module 49 selectively calculates a power loss of the engine system 10 and determines a fuel efficiency of the engine based thereon [0022] Referring now to FIG 2, an exemplary embodiment of the control module 49 uses an engine torque value (TORQ), an engine speed value (RPM), a coolant temperature value (COOL), a barometric pressure value (BARO), an oil temperature value (OT) and an ambient temperature value (AMBT) as inputs to calculate power loss More specifically, the TORQ, RPM, COOL, BARO, OT, and AMBT values may be current values determined based on, but not limited to, the signals from the sensors 36, 38, 42, 44, 46 In an alternate configuration, the TORQ, RPM, COOL BARO, OT and AMBT may be values determined by the control module 49 to calculate a theoretical power loss [0023] The control module 49 includes an air intake calculation module 50, a fuel mass rate calculation module 52 and a power loss calculation module 54 The air intake calculation module 50 determines a final mass of air-per- cyhnder (APCF) and/or a final mass air flow rate (MAFF) More specifically, APCF and MAFF are based on the same inputs TORQ, RPM, COOL, BARO, OT and AMBT The relationship between APCF and MAFF is shown in the following equation where N, is the number of cylinders 18 of the engine 12 and kCOnv is a constant determined based on a unit conversion For ease of discussion, APCF is used in context to further illustrate the present disclosure [0024] The fuel mass rate calculation module 52 determines a fuel mass rate (Mf) based on APCF, RPM, and AF\|T More specifically, the Mf may be based on the following equation The constant k is a predetermined value that may vary according to different engine systems AFrr is a calculated air fuel ratio that is discussed in further detail below [0025] The power loss calculation module 54 determines a power loss value (PL) based on Mf, RPM, and TORQ More specifically, the PL may be based on the following equation TORQ0pt, RPMopt and Mopt are the optimal engine torque, optimal engine speed, and optimal fuel mass flow rate values, respectively, and can be selected to represent one operating point for the engine at one reference coolant temperature and one reference barometric pressure Alternatively, the values of TORQopt, RPM0pi arid Mopt can be determined from pre-stored look-up tables based on the current coolant temperature (COOL) and current barometric pressure (BARO) The power loss can also be evaluated using different TORQopt and Mopt for each RPM More specifically, RPMopt set equal to RPM and the values TORQopt and Mopt are determined from a pre-stored look-up based on RPM [0026] Various embodiments of the control module 49 may include any number of modules The modules shown in FIG 2 may be combined and/or partitioned further without departing from the present disclosure [0027] Referring now to FIG 3, an exemplary embodiment of the calculation module 50 including an initial calculation APC sub-module 56, an iterative APC calculation sub-module 58, a spark advance calculation sub- module 60, a cam phaser position calculation sub-module 62 and an air/fuel ratio calculation sub-module 64 The initial APC calculation sub-module 56 outputs an initial APC (APC\|N) based on TORQ, RPM, COOL, BARO, OT, and AMBT For example, APC\|N may be based on the following inverse model torque equation SIN, IIN, EIN, and AF!N are initial values for spark advance, intake cam phaser position, exhaust cam phaser position and air/fuel ratio, respectively The S\|N, l\|N, E\|N, and AF,N maybe predetermined lookup table values that are accessed as a function of TORQ, RPM, COOL, BARO, OT and AMBT [0028] The iterative APC calculation sub-module 58 determines an iterative APC (APC\|T) until the engine is stable and then outputs APCF to the fuel mass rate calculation module 52 More specifically, APCrr may be based on the following inverse model torque equation TORQ, RPM, COOL, OT, BARO, and AMBT are the current values as provided by the respective sensors S\|T, I IT, Err, and AF\|T are iterative values for spark advance, intake cam phaser position, exhaust cam phaser position, and air/fuel ratio, respectively The iterative APC calculation sub-module 58 outputs APCF when the engine is stable More specifically, engine stability is determined when a difference between a prior APCrr and the current APCrr is less than a predetermined value The APCF IS set equal to the current APCrr The spark advance calculation sub-module 60 outputs Sif based on the current APCIT, RPM and COOL The cam phaser position calculation sub-module 62 outputs I IT and Err .based on the current APCIT, RPM and COOL The AF ratio calculation sub- module 64 outputs AFIT based on the APC,T, RPM, and COOL [0029] Various embodiments of the calculation module 50 may include any number of sub-modules The sub-modules shown in FIG 3 may be combined and/or partitioned further without departing from the present disclosure [0030] Referring now to FIG 4, exemplary steps that are executed to calculate power loss will be described in detail In step 220, control determines APCIN In step 230, control determines a current APCrr (APC\|T(i), where i is a time step) based on APC\|N or a prior iterative APC (APCrr(i-l)) More specifically, the first iterative APC calculation is based on APCiN and subsequent iterative APC calculations are based on APC\|T(i-1) [0031] In step 240, control determines a difference (DIFF) between APCIT(I) and APCIT(I-1) In step 250, control determines whether DIFF is less than a predetermined threshold value (THR) If DIFF is greater than THR, the iterative solution is deemed to be at an intermediate state and control loops back to'step 230 If DIFF is less than THR, the iterative solution is considered complete and control proceeds to output APCF in step 255 More specifically, APCF IS set equal to or otherwise provided as APC\|T(i) In step 260, control calculates Mf based on APCF, AF\|T and RPM values In step 270, control calculates a power loss (PL) value based on Mf, TORQ and RPM values and control ends Control can subsequently determine an instantaneous fuel efficiency of the engine based on PL [0032] It is also anticipated that the present disclosure can be implemented using an engine mass air flow (MAF), as opposed to APC In this case, APC is substituted for using the determined MAF [0033] It is further anticipated that the present disclosure can be modified for implementation with diesel engine systems For example, in the case of a diesel engine system, APC is not determined Instead, an engine torque model is provided, which is primarily based on a fuel mass flow rate The inverse torque model, in this case, provides an estimate of the required fuel mass flow rate [0034] Those skilled in the art can now appreciate from the foregoing description that the broad teachings of the present disclosure can be implemented in a variety of forms Therefore, while this disclosure has been described in connection with particular examples thereof, the true scope of the disclosure should not be so limited since other modifications will become apparent to the skilled practitioner upon a study of the drawings, specification, and the following claims WE CLAIM : 1. A fuel efficiency estimation system for determining a fuel efficiency of an internal combustion engine (12) comprising: a first module (50) that determines a current iterative intake air mass value provided to said engine (12) and compares said current iterative intake air mass value to a previous iterative intake air mass value, said first module (50) providing said current iterative intake air mass value as a final intake air mass value when a difference between said current iterative intake air mass value and said previous iterative intake air mass value is less than a predetermined threshold value; a second module (52) that determines a fuel mass rate value based on said final air intake mass value; and a third module (50) that determines a power loss for the internal combustion engine (12) based on said fuel mass rate value, wherein a fuel efficiency of the engine (12) is determined based on said power loss. 2. The fuel efficiency estimation system of claim 1 wherein said first module (50) comprises a first sub-module (56) that generates an initial intake air mass value based on at least one of an engine speed value, an engine torque value and an engine coolant temperature value. 3. The fuel efficiency estimation system as claimed in claim 2, wherein said first module (50) further comprises a second sub-module (58) that outputs said current iterative intake air mass value based on at least one of said engine speed value, said engine torque value and said coolant temperature value. 4. The fuel efficiency estimation system as claimed in claim 3, wherein said first module (50) further comprises: a third sub-module (60) that determines a spark advance value; a fourth sub-module (62) that determines an intake and exhaust cam phaser position value; and a fifth sub-module (64) that determines an air/fuel ratio. 5. The fuel efficiency estimation system as claimed in claim 4, wherein said spark advance value, said intake and exhaust cam phaser positions values and said air/fuel ratio are calculated based on said current iterative intake air mass value, said engine speed value and said coolant temperature value. 6. The fuel efficiency estimation system as claimed in claim 5, wherein said second sub-module (58) calculates said current iterative intake air mass value based on said spark advance value, said intake and exhaust cam phaser position values and said air/fuel ratio value. 7. The fuel efficiency estimation system as claimed claim 3, wherein said second sub-module (58) determines said difference between said current iterative intake air mass value and said previous iterative intake air mass value. 8. The fuel efficiency estimation system as claimed in claim 7, wherein said second sub-module (58) outputs said final intake air mass value when said difference is less than said predetermined threshold value. 9. The fuel efficiency estimation system as claimed in claim 7, wherein said second sub-module (58) updates said current iterative intake air mass value when said difference is greater than said predetermined threshold value. 10. A method of determining a fuel efficiency of an internal combustion engine, comprising: determining a current iterative intake air mass value provided to said engine; comparing said current iterative intake air mass value to a previous iterative intake air mass value; providing said current iterative intake air mass value as a final intake air mass value when a difference between said current iterative intake air mass value and said previous iterative intake air mass value is less than a predetermined threshold value; determining a fuel mass rate value based on said final intake air mass value; calculating a power loss of the internal combustion engine based on said fuel mass rate value; and determining the fuel efficiency based on said power loss. 11. The method as claimed in claim 10, comprising determining an initial intake air mass value based on at least one of an engine speed value, an engine torque value and an engine coolant temperature value. 12. The method as claimed claim 11, further comprising determining said current iterative intake air mass value based on at least one of said engine speed value, said engine torque value and said coolant temperature value. 13. The method as claimed in claim 12, comprising: determining a spark advance value; determining a intake and exhaust cam phaser position values; and determining an air/fuel ratio. 14. The method as claimed in claim 13, wherein said spark advance value, said intake and exhaust cam phaser positions values and said air/fuel ratio are calculated based on at least one of said current iterative intake air mass value, said engine speed value and said coolant temperature value. 15. The method as claimed in claim 14, wherein said current iterative intake air mass value is based on at least one of said spark advance value, said intake and exhaust cam phaser position values and said air/fuel ratio value. 16. The method as claimed in claim 10, wherein said current iterative intake air mass value is updated if said difference is greater than said predetermined threshold value. ABSTRACT TITLE " A FUEL EFFICIENCY ESTIMATION SYSTEM AND A METHOD FOR DETERMINING A FUEL EFFICIENCY OF AN INTERNAL COMBUSTION SYSTEM'. The invention relates to a fuel efficiency estimation system for determining a fuel efficiency of an internal combustion engine (12) comprising a first module (50) that determines a current iterative intake air mass value provided to said engine (12) and compares said current iterative intake air mass value to a previous iterative intake air mass value, said first module (50) providing said current iterative intake air mass value as a final intake air mass value when a difference between said current iterative intake air mass value and said previous iterative intake air mass value is less than a predetermined threshold value;a second module (52) that determines a fuel mass rate value based on said final air intake mass value; and a third module (50) that determines a power loss for the internal combustion engine (12) based on said fuel mass rate value, wherein a fuel efficiency of the engine (12) is determined based on said power loss.

Full Text

CROSS REFERENCE TO RELATED APPLICATIONS
The application claims the benefit of US Provisional Application No.60/755,001
filed on December 29, 2005. The disclosure of the above application is
incorporated herein by reference.
FIELD OF THE INVENTION
The present disclosure relates to engine control systems, and more particularly
to an engine control system that determines a fuel efficiency of an internal
combustion based on a power loss of the engine.
BACKGROUND OF THE INVENTION
Vehicles include an internal combustion engine that generates drive torque. More
Particularly, the engine draws in air and mixes the air with fuel to form a
combustion mixture. The combustion mixture is compressed within cylinders and
is combusted to drive pistons that are disposed within the cylinders. The pistons
drive a crankshaft that transfers drive torque to a transmission and a drivetrain.
Vehicle manufacturers typically use a dynamometer to evaluate vehicle
performance. For example, a dynamometer may determine optimal engine
torque output for a range of engine speeds. However, actual torque output may
be different than the optimal torque output generated by the vehicle in
controlled conditions. More specifically, the actual torque output may be affected
by external conditions including, but not limited to air temperature himidity
and/or barometric pressure.

The document D1 discloses: A preferred input torque for a hybrid power train is
determined within a solution space of feasible input torques in accordance with a
plurality of powertrain system constraints that results in a minimum overall
powertrain system loss. System power losses and battery utilization costs system
loss is converged upon to determine the preferred input torque.
The document D2 discloses:. A two-mode, compound-split, electro-mechanical
transmission utilizes an input member for receiving power from an engine, and
an output member for delivering power from the transmission. First and second
motor/generators are operatively connected to an energy storage device through
a control for interchanging electrical power among the storage device, the first
motor/generator and the second motor/generator. The transmission employs
three planetary gear sets. Each planetary gear arrangement utilizes first, second
and third gear members. At least one of the gear members in the first or second
planetary gear sets is connected to the first motor/generator. One of the gear
members of the first or second planetary gear sets is continuously connected to
one of the gear members in the third planetary gear set. Another gear member
of the first or second planetary gear set is operatively connected to the input
member, and one gear member of the third planetary gear set is selectively
connected to ground. A lock-up clutch selectively locks two of the planetary gear
sets in a 1:1 ratio.

SUMMARY OF THE INVENTION
The present disclosure provides a fuel efficiency estimation system for
determining a fuel efficiency of an internal combustion engine. The system
includes a first module that determines a final air intake value and a second
module that determines a fuel mass rate value based on the final air intake
value. A third module determines the power loss for the internal combustion
engine based on the fuel mass rate value. A fuel efficiency of the engine is
determined based on the power loss.
In other features, the first module includes a first sub-module that generates an
initial air intake value based on at least one of an engine speed value, an engine
torque value and an engine coolant temperature value. The first module further
includes a second sub-module that outputs a current iterative air intake value
based on at least one of the engine speed value, the engine torque value and
the coolant temperature value.
In other features, the first module further includes a third sub-module that
determines a spark advance value, a fourth sub-module that determines an
intake and exhaust cam phaser position value and a fifth sub-module that
determines an air/fuel ratio. The spark advance value, the intake and exhaust
cam phaser positions values and the air/fuel ratio are calculated based on the
current iterative air intake value, the engine speed value and the coolant
temperature value.
In still other features, the second sub-module calculates the current iterative air
intake value based on the spark advance value, the intake and exhaust cam
phaser position values and the air/fuel ratio value.

In yet other features, the second sub-module determines a difference between
the current iterative air intake value and a prior iterative air intake value. The
second sub-module outputs a final iterative air intake value when the difference
is less than a predetermined threshold value. The second sub-module updates
the iterative air intake value when the difference is greater than the
predetermined threshold value.
Further areas of applicability will become apparent from the description provided
herein. It should be under. 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 present disclosure will become more fully understood from the detailed
description and the accompanying drawings, wherein
Figure 1 is a functional block diagram of an engine system.
Figure 2 is an exemplary block diagram of a control module that calculates a fuel
efficiency of the engine system according to he present disclosure.
Figure 3 is an exemplary block diagram of an air intake calculation module
according to the present disclosure, and
Figure 4 is a flowchart illustrating exemplary steps executed by the fuel efficiency
control according to the present disclosure.

DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The following description is merely exemplary in nature and is in no way
intended to limit the disclosure, its application, or uses. As used herein, the term
module or device refers to an application specific integrated circuit (ASIC), an
electronic circuit, a processor (shared, dedicated, or group) and memory that
executes one or more software or firmware programs, a combinational logic
circuit and/or other suitable components that provides the described
functionality.
According to the present disclosure, a fuel efficiency of an engine is calculated
as a function of a power loss of the engine, which is based on the difference
between an optimal power output value and an estimated power output value.
More specifically, the estimated power is calculated during a stable or steady
state engine condition based on current engine speed, engine torque and coolant
temperature values.
Referring now to figure 1, an engine system 10 includes an engine 12 that-
combusts an air/fuel mixture to produce drive torque. Air is drawn into an intake
manifold 14 through a throttle 16. The throttle 16 regulates air flow into the
intake manifold 14. The air is mixed with fuel and is combusted within

cylinders 18 to produce drive torque Although four cylinders are illustrated, it
can be appreciated that the engine 12 may include additional or fewer cylinders
18 For example, engines having 2, 3, 5, 6, 8, 10 and 12 cylinders are
contemplated
[0019] A fuel injector (not shown) injects fuel that is combined with air
to form an air/fuel mixture that is combusted within the cylinder 18 A fuel
injection system 20 regulates the fuel injector to provide a desired air-to-fuel ratio
within each cylinder 18 An intake valve 22 selectively opens and closes to
enable the air/fuel mixture to enter the cylinder 18 The position of the intake
valve is regulated by an intake cam shaft 24 A piston (not shown) compresses
the air/fuel mixture within the cylinder 18 After the combustion event, an
exhaust valve 28 selectively opens and closes to enable the exhaust gases to
exit the cylinder 18 The position of the exhaust valve is regulated by an exhaust
cam shaft 30 The piston drives a crankshaft (not shown) to produce drive
torque The crankshaft rotatably drives camshafts 24,30 using a timing chain
(not shown) to regulate the timing of intake and exhaust valves 22, 28 Although
dual camshafts are shown, a single camshaft may be used
[0020] The engine 12 may include an intake cam phaser 32 and/or an
exhaust cam phaser 34 that respectively regulate rotational timing of the intake
and exhaust cam shafts 24, 30 relative to a rotational position of the crankshaft
More specifically, a phase angle of the intake and exhaust cam phasers 32, 34
may be retarded or advanced to regulate the rotational timing of the intake and
exhaust cam shafts 24, 30

[0021] A coolant temperature sensor 36 is responsive to the
temperature of a coolant circulating through the engine 12 and generates a
coolant temperature signal 37 A barometric pressure sensor 38 is responsive
to atmospheric pressure and generates a barometric pressure signal 39 An
engine speed sensor 42 is responsive to the engine speed and outputs an
engine speed signal 43 A temperature sensor 44 is responsive to ambient
temperature and outputs a temperature signal 45 An oil temperature sensor 46
is responsive to oil temperature and outputs an oil temperature signal 47 A
control module 49 regulates operation of the engine system 10 based on the
various sensor signals The engine control module 49 selectively calculates a
power loss of the engine system 10 and determines a fuel efficiency of the
engine based thereon
[0022] Referring now to FIG 2, an exemplary embodiment of the
control module 49 uses an engine torque value (TORQ), an engine speed value
(RPM), a coolant temperature value (COOL), a barometric pressure value
(BARO), an oil temperature value (OT) and an ambient temperature value
(AMBT) as inputs to calculate power loss More specifically, the TORQ, RPM,
COOL, BARO, OT, and AMBT values may be current values determined based
on, but not limited to, the signals from the sensors 36, 38, 42, 44, 46 In an
alternate configuration, the TORQ, RPM, COOL BARO, OT and AMBT may be
values determined by the control module 49 to calculate a theoretical power loss
[0023] The control module 49 includes an air intake calculation module
50, a fuel mass rate calculation module 52 and a power loss calculation module

54 The air intake calculation module 50 determines a final mass of air-per-
cyhnder (APCF) and/or a final mass air flow rate (MAFF) More specifically, APCF
and MAFF are based on the same inputs TORQ, RPM, COOL, BARO, OT and
AMBT The relationship between APCF and MAFF is shown in the following
equation

where N, is the number of cylinders 18 of the engine 12 and kCOnv is a constant
determined based on a unit conversion For ease of discussion, APCF is used in
context to further illustrate the present disclosure
[0024] The fuel mass rate calculation module 52 determines a fuel
mass rate (Mf) based on APCF, RPM, and AF|T More specifically, the Mf may be
based on the following equation

The constant k is a predetermined value that may vary according to different
engine systems AFrr is a calculated air fuel ratio that is discussed in further
detail below
[0025] The power loss calculation module 54 determines a power loss
value (PL) based on Mf, RPM, and TORQ More specifically, the PL may be
based on the following equation

TORQ0pt, RPMopt and Mopt are the optimal engine torque, optimal engine speed,
and optimal fuel mass flow rate values, respectively, and can be selected to

represent one operating point for the engine at one reference coolant
temperature and one reference barometric pressure Alternatively, the values of
TORQopt, RPM0pi arid Mopt can be determined from pre-stored look-up tables
based on the current coolant temperature (COOL) and current barometric
pressure (BARO) The power loss can also be evaluated using different TORQopt
and Mopt for each RPM More specifically, RPMopt set equal to RPM and the
values TORQopt and Mopt are determined from a pre-stored look-up based on
RPM
[0026] Various embodiments of the control module 49 may include any
number of modules The modules shown in FIG 2 may be combined and/or
partitioned further without departing from the present disclosure
[0027] Referring now to FIG 3, an exemplary embodiment of the
calculation module 50 including an initial calculation APC sub-module 56, an
iterative APC calculation sub-module 58, a spark advance calculation sub-
module 60, a cam phaser position calculation sub-module 62 and an air/fuel ratio
calculation sub-module 64 The initial APC calculation sub-module 56 outputs an
initial APC (APC|N) based on TORQ, RPM, COOL, BARO, OT, and AMBT For
example, APC|N may be based on the following inverse model torque equation

SIN, IIN, EIN, and AF!N are initial values for spark advance, intake cam phaser
position, exhaust cam phaser position and air/fuel ratio, respectively The S|N, l|N,
E|N, and AF,N maybe predetermined lookup table values that are accessed as a
function of TORQ, RPM, COOL, BARO, OT and AMBT

[0028] The iterative APC calculation sub-module 58 determines an
iterative APC (APC|T) until the engine is stable and then outputs APCF to the fuel
mass rate calculation module 52 More specifically, APCrr may be based on the
following inverse model torque equation

TORQ, RPM, COOL, OT, BARO, and AMBT are the current values as provided
by the respective sensors S|T, I IT, Err, and AF|T are iterative values for spark
advance, intake cam phaser position, exhaust cam phaser position, and air/fuel
ratio, respectively The iterative APC calculation sub-module 58 outputs APCF
when the engine is stable More specifically, engine stability is determined when
a difference between a prior APCrr and the current APCrr is less than a
predetermined value The APCF IS set equal to the current APCrr The spark
advance calculation sub-module 60 outputs Sif based on the current APCIT, RPM
and COOL The cam phaser position calculation sub-module 62 outputs I IT and
Err .based on the current APCIT, RPM and COOL The AF ratio calculation sub-
module 64 outputs AFIT based on the APC,T, RPM, and COOL
[0029] Various embodiments of the calculation module 50 may include
any number of sub-modules The sub-modules shown in FIG 3 may be
combined and/or partitioned further without departing from the present
disclosure
[0030] Referring now to FIG 4, exemplary steps that are executed to
calculate power loss will be described in detail In step 220, control determines
APCIN In step 230, control determines a current APCrr (APC|T(i), where i is a

time step) based on APC|N or a prior iterative APC (APCrr(i-l)) More specifically,
the first iterative APC calculation is based on APCiN and subsequent iterative
APC calculations are based on APC|T(i-1)
[0031] In step 240, control determines a difference (DIFF) between
APCIT(I) and APCIT(I-1) In step 250, control determines whether DIFF is less
than a predetermined threshold value (THR) If DIFF is greater than THR, the
iterative solution is deemed to be at an intermediate state and control loops back
to'step 230 If DIFF is less than THR, the iterative solution is considered
complete and control proceeds to output APCF in step 255 More specifically,
APCF IS set equal to or otherwise provided as APC|T(i) In step 260, control
calculates Mf based on APCF, AF|T and RPM values In step 270, control
calculates a power loss (PL) value based on Mf, TORQ and RPM values and
control ends Control can subsequently determine an instantaneous fuel
efficiency of the engine based on PL
[0032] It is also anticipated that the present disclosure can be
implemented using an engine mass air flow (MAF), as opposed to APC In this
case, APC is substituted for using the determined MAF
[0033] It is further anticipated that the present disclosure can be
modified for implementation with diesel engine systems For example, in the
case of a diesel engine system, APC is not determined Instead, an engine
torque model is provided, which is primarily based on a fuel mass flow rate The
inverse torque model, in this case, provides an estimate of the required fuel mass
flow rate

[0034] Those skilled in the art can now appreciate from the foregoing
description that the broad teachings of the present disclosure can be
implemented in a variety of forms Therefore, while this disclosure has been
described in connection with particular examples thereof, the true scope of the
disclosure should not be so limited since other modifications will become
apparent to the skilled practitioner upon a study of the drawings, specification,
and the following claims

WE CLAIM :
1. A fuel efficiency estimation system for determining a fuel efficiency of an
internal combustion engine (12) comprising:
a first module (50) that determines a current iterative intake air mass value
provided to said engine (12) and compares said current iterative intake air mass
value to a previous iterative intake air mass value, said first module (50)
providing said current iterative intake air mass value as a final intake air mass
value when a difference between said current iterative intake air mass value and
said previous iterative intake air mass value is less than a predetermined
threshold value;
a second module (52) that determines a fuel mass rate value based on said final
air intake mass value; and
a third module (50) that determines a power loss for the internal combustion
engine (12) based on said fuel mass rate value, wherein a fuel efficiency of the
engine (12) is determined based on said power loss.
2. The fuel efficiency estimation system of claim 1 wherein said first module (50)
comprises a first sub-module (56) that generates an initial intake air mass value
based on at least one of an engine speed value, an engine torque value and an
engine coolant temperature value.

3. The fuel efficiency estimation system as claimed in claim 2, wherein said first
module (50) further comprises a second sub-module (58) that outputs said
current iterative intake air mass value based on at least one of said engine speed
value, said engine torque value and said coolant temperature value.
4. The fuel efficiency estimation system as claimed in claim 3, wherein said first
module (50) further comprises:
a third sub-module (60) that determines a spark advance value;
a fourth sub-module (62) that determines an intake and exhaust cam phaser
position value; and
a fifth sub-module (64) that determines an air/fuel ratio.
5. The fuel efficiency estimation system as claimed in claim 4, wherein said
spark advance value, said intake and exhaust cam phaser positions values and
said air/fuel ratio are calculated based on said current iterative intake air mass
value, said engine speed value and said coolant temperature value.
6. The fuel efficiency estimation system as claimed in claim 5, wherein said
second sub-module (58) calculates said current iterative intake air mass value
based on said spark advance value, said intake and exhaust cam phaser position
values and said air/fuel ratio value.

7. The fuel efficiency estimation system as claimed claim 3, wherein said second
sub-module (58) determines said difference between said current iterative intake
air mass value and said previous iterative intake air mass value.
8. The fuel efficiency estimation system as claimed in claim 7, wherein said
second sub-module (58) outputs said final intake air mass value when said
difference is less than said predetermined threshold value.
9. The fuel efficiency estimation system as claimed in claim 7, wherein said
second sub-module (58) updates said current iterative intake air mass value
when said difference is greater than said predetermined threshold value.
10. A method of determining a fuel efficiency of an internal combustion engine,
comprising:
determining a current iterative intake air mass value provided to said engine;
comparing said current iterative intake air mass value to a previous iterative
intake air mass value;
providing said current iterative intake air mass value as a final intake air mass
value when a difference between said current iterative intake air mass value and
said previous iterative intake air mass value is less than a predetermined
threshold value;

determining a fuel mass rate value based on said final intake air mass value;
calculating a power loss of the internal combustion engine based on said fuel
mass rate value; and
determining the fuel efficiency based on said power loss.
11. The method as claimed in claim 10, comprising determining an initial intake
air mass value based on at least one of an engine speed value, an engine torque
value and an engine coolant temperature value.
12. The method as claimed claim 11, further comprising determining said
current iterative intake air mass value based on at least one of said engine speed
value, said engine torque value and said coolant temperature value.
13. The method as claimed in claim 12, comprising:
determining a spark advance value;
determining a intake and exhaust cam phaser position values; and
determining an air/fuel ratio.
14. The method as claimed in claim 13, wherein said spark advance value, said
intake and exhaust cam phaser positions values and said air/fuel ratio are

calculated based on at least one of said current iterative intake air mass value,
said engine speed value and said coolant temperature value.
15. The method as claimed in claim 14, wherein said current iterative intake air
mass value is based on at least one of said spark advance value, said intake and
exhaust cam phaser position values and said air/fuel ratio value.
16. The method as claimed in claim 10, wherein said current iterative intake air
mass value is updated if said difference is greater than said predetermined
threshold value.

ABSTRACT

TITLE " A FUEL EFFICIENCY ESTIMATION SYSTEM AND A METHOD FOR
DETERMINING A FUEL EFFICIENCY OF AN INTERNAL COMBUSTION
SYSTEM'.
The invention relates to a fuel efficiency estimation system for determining a fuel
efficiency of an internal combustion engine (12) comprising a first module (50)
that determines a current iterative intake air mass value provided to said engine
(12) and compares said current iterative intake air mass value to a previous
iterative intake air mass value, said first module (50) providing said current
iterative intake air mass value as a final intake air mass value when a difference
between said current iterative intake air mass value and said previous iterative
intake air mass value is less than a predetermined threshold value;a second
module (52) that determines a fuel mass rate value based on said final air intake
mass value; and a third module (50) that determines a power loss for the
internal combustion engine (12) based on said fuel mass rate value, wherein a
fuel efficiency of the engine (12) is determined based on said power loss.

Documents:

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Patent Number

271342

Indian Patent Application Number

1398/KOL/2006

PG Journal Number

08/2016

Publication Date

19-Feb-2016

Grant Date

17-Feb-2016

Date of Filing

26-Dec-2006

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	JOHN P. BLANCHARD	HOLLY, MICHIGAN 3810 CA THERINE ANNE LANE HOLLY, MICHIGAN 48442
2	MICHAEL LIVSHIZ	2904 LESLIE PARK ANN ARBOR, MICHIGAN 28105
3	JOHN L. LAHTI	NOVI, MICHIGAN 47111 MANHATTAN CIRCLE NOVI, MICHIGAN 48374
4	ANTHONY H. HEAP	ANN ARBOR, MICHIGAN 2969 LESLIE PARK CIRCLE ANN ARBOR, MICHIGAN 48105

PCT International Classification Number

N/A

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	11/611,373	2006-12-15	U.S.A.
2	60/755,001	2005-12-29	U.S.A.