Title of Invention

AN ENGINE CONTROL SYSTEM FOR AND A METHOD OF REGULATING OPERATION OF AN ENGINE

Abstract An engine control system for regulating operation of an engine having a throttle includes a first module that determines an intermediate parameter based on engine operating parameters and a second module that determines a pressure upstream of the throttle based on the intermediate parameter. A third module regulates operation of the engine based on the pressure. The engine operation is regulated based on a pre-determined relationship between a throttle position and ah effective throttle area.
Full Text 1
GP-307912-PTE-CD
ENGINE PRE-THROTTLE PRESSURE ESTIMATION
FIELD
[0001] The present disclosure relates to internal combustion
engines, and more particularly to estimating the air pressure upstream of the
throttle of an internal combustion engine.
BACKGROUND
[0002] The statements in this section merely provide background
information related to the present disclosure and may not constitute prior art.
[0003] Internal combustion engines combust a fuel and air mixture
to produce drive torque. More specifically, air is drawn into the engine
through a throttle. The air is mixed with fuel and the air and fuel mixture is
compressed within a cylinder using a piston. The air and fuel mixture is
combusted within the cylinder to reciprocally drive the piston within the
cylinder, which in turn rotationally drives a crankshaft of the engine.
[0004] Engine operation is regulated based on several parameters
including, but not limited to, intake air temperature (TPRE), manifold absolute
pressure (MAP), throttle position (TPS) and engine RPM. With specific
reference to the throttle, the state parameters (e.g., air temperature and
pressure) before the throttle are good references that can be used for engine
control and diagnostic. For example, proper functioning of the throttle can be
monitored by calculating the flow through the throttle for a given throttle
position and then comparing the calculated air flow to a measured or actual
air flow. As a result, the total or stagnation air pressure before the throttle
(i.e., the pre-throttle air pressure) is critical to accurately calculate the flow
through the throttle. Alternatively, the total pressure and/or static pressure
can be used to monitor air filter restriction.

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[0005] Traditional internal combustion engines include a pre-throttle
pressure sensor that directly measures the pre-throttle pressure. However,
such additional hardware increases cost and manufacturing time, and is also
a maintenance concern because proper operation of the sensor must be
monitored and the sensor must be replaced if not functioning properly.
SUMMARY
[0006] Accordingly, the present invention provides an engine control
system for regulating operation of an engine having a throttle. The engine
control system includes a first module that determines an intermediate
parameter based on engine operating parameters and a second module that
determines a pressure upstream of the throttle based on the intermediate
parameter. A third module regulates operation of the engine based on the
pressure. The engine operation is regulated based on a pre-determined
relationship between a throttle position and an effective throttle area.
[0007] In one feature, the engine control system further includes a
fourth module that compares the intermediate parameter to a threshold value.
The second module determines the pressure based on the comparison.
[0008] In other features, the engine control system further includes
a fourth module that determines a pressure ratio based on the intermediate
parameter. The fourth module sets the pressure ratio equal to a constant
value if the intermediate parameter is not less than a threshold value.
Alternatively, the fourth module determines the pressure ratio based on the
intermediate parameter if the intermediate parameter is not less than a
threshold value.
[0009] In still another feature, the engine control system further
includes a fourth module that determines a pressure ratio based on the
intermediate parameter and a fifth module that determines a stagnation
pressure based on the pressure ratio.
[0010] In yet another feature, the third module determines whether
a component of the engine is functioning properly based on said pressure.

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[0011] 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.
DRAWINGS
[0012] The drawings described herein are for illustration purposes
only and are not intended to limit the scope of the present disclosure in any
way.
[0013] Figure 1 is a functional block diagram of an internal
combustion engine system that is regulated in accordance with the pre-throttle
pressure estimation control of the present invention;
[0014] Figure 2 is a graph that graphically illustrates an exemplary
look-up table for determining a pressure ratio based on an intermediate value
in accordance with the pre-throttle pressure estimation control of the present
invention;
[0015] Figure 3 is a flowchart illustrating exemplary steps that are
executed by the pre-throttle estimation control of the present invention;
[0016] Figure 4 is a flowchart illustrating exemplary steps that are
executed to develop a relationship between throttle position and an effective
throttle area; and
[0017] Figure 5 is a functional block diagram illustrating exemplary
modules that execute the pre-throttle pressure estimation control.
DETAILED DESCRIPTION
[0018] The following description of the preferred embodiment is
merely exemplary in nature and is in no way intended to limit the invention, its
application, or uses. For purposes of clarity, the same reference numbers will
be used in the drawings to identify similar elements. 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

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one or more software or firmware programs, a combinational logic circuit, or
other suitable components that provide the described functionality.
[0019] Referring now to Figure 1, an exemplary internal combustion
engine system 10 is illustrated. The engine system 10 includes an engine 12,
an intake manifold 14 and an exhaust manifold 16. Air is drawn into the
intake manifold 14 through a throttle 18. The air is mixed with fuel, and the
fuel and air mixture is combusted within a cylinder 20 of the engine 12. More
specifically, the fuel and air mixture is compressed within the cylinder 20 by a
piston (not shown) and combustion is initiated. The combustion process
releases energy that is used to reciprocally drive the piston within the cylinder
20. Exhaust that is generated by the combustion process is exhausted
through the exhaust manifold 16 and is treated in an exhaust after-treatment
system (not shown) before being released to atmosphere. Although a single
cylinder 20 is illustrated, it is anticipated that the pre-throttle estimation control
of the present invention can be implemented with engines having more than
one cylinder.
[0020] A control module 30 regulates engine operation based on a
plurality of engine operating parameters including, but not limited to, a pre-
throttle static pressure (PPRE), a pre-throttle stagnation pressure (PPREO) (i.e.,
the air pressures upstream of the throttle), an intake air temperature (TPRE), a
mass air flow (MAF), a manifold absolute pressure (MAP), an effective throttle
area (AEFF) and an engine RPM. PPREO and PPRE are determined based on the
pre-throttle estimation control of the present invention, as explained in further
detail below. TPRE, MAF, MAP and engine RPM are determined based on
signals generated by a TPRE sensor 32, a MAF sensor 34, a MAP sensor 36
and an engine RPM sensor 38, respectively, which are all standard sensors of
an engine system. AEFF is determined based on a throttle position signal that
is generated by a throttle position sensor, which is also a standard sensor. A
barometric pressure (PBARO) is monitored using a barometric pressure sensor
40. A throttle position sensor 42 generates a throttle position signal (TPS).
The relationship between AEFF to TPS is pre-determined using engine
dynamometer testing with a temporary stagnation pressure sensor (shown in

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phantom in Figure 1) installed. Production vehicles include the relationship
pre-programmed therein and therefore do not require the continued presence
of the pressure sensor.
[0021] The pre-throttle pressure estimation control of the present
invention determines PPRE and PPREo based on engine operating parameters
including, but not limited to MAF, AEFF, TPRE and MAP. More specifically, the
throttle 18 and the associated pre and post air passages 50, 52, respectively,
are provided as a control volume and the air flow therethrough is treated as a
one-dimensional, quasi-steady state compressible gas flow. Accordingly, the
following relationship is provided:

where PPREO is the pre-throttle stagnation pressure (i.e., the pressure that the
air would reach if it were brought to zero speed, via a steady, adiabatic, quasi-
static process with no external work) measured in kPa, TPREo is the pre-throttle
stagnation temperature (i.e., the temperature that the fluid would reach if it
were brought to zero speed by a steady, adiabatic process with no external
work) measured in K, R is the ideal gas constant for air (i.e., 288.17
Nm/(kgK)). O is a unit-less coefficient equal to 0.6847 for sonic air flow (i.e.,
where MAP/PPRE0 is less than 0.528) and is determined based on the
following relationship for sub-sonic air flow:

where k is the ratio of specific heats for air (i.e., 1.4) and PR is equal to the
ratio of MAP to PPREo- TPRE0 is determined based on the following
relationship:

where V is the air velocity upstream of the throttle and is determined based on
the MAF signal, p and the throttle intake pipe geometry, p is the air density
(kg/m3) and can be assumed to be the same value as ambient air because the

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flow through air filter system has such a low Mach number (e.g., «0.3) that it
can be treated as incompressible air flow.
[0022] Equations 1 and 2 can be combined to provide the following
relationship:

[0023] PPREO is determined by first calculating fNEW based on MAF,
R, TPREO, AEFF and MAP in accordance with Equation 7. If fNEW is greater
than or equal to 1.2968 (i.e., sonic air flow) f is clamped to 0.6847 and PPREo
is determined based on Equation 4. As provided above, PR is set equal to a
constant (C) (e.g., 0.528) for sonic air flow. If fNEW is less than a threshold
value (XTHR) 1.2968 (i.e., sub-sonic air flow), PR is calculated based on fNEW-
More specifically, PR can be calculated using Equation 8 or can be determined

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using a look-up table. An exemplary look-up table is graphically illustrated in
Figure 2.
[0024] PPREO value can be determined by dividing MAP by PR, and is
used to control engine operation and/or for diagnostics. For example, during
engine control, PPREO, MAF, MAP and TPREo can be used to calculate the
throttle position. If the air flow into the engine needs to change, the change in
throttle position can be predicted for the current air flow to the desired air flow.
PPREO, along with other parameters, can be used to calculate a theoretical
MAF, which is comparable to that determined by the MAF sensor. In this
manner, it can be determined whether the MAF sensor and/or the throttle
is/are functioning properly. As a result, throttle position error and/or MAF
error can be diagnosed, depending on what other conditions are known.
[0025] The pre-throttle estimation control also provides the following
relationship:

Accordingly, PPRE is determined based on PPREO using Equation 9. PPRE can
also be used to control engine operation and for diagnostics. For example,
during engine control, PPRE, MAF, PBARO and TPREo can be used to calculate or
monitor the air filter restriction conditions.
[0026] PPREO can be measured directly during calibration of the
engine operating parameters, for example, when calibrating AEFF versus
throttle position. More specifically, calibrating AEFF versus throttle position,
PPREO is concurrently measured to correspond to the AEFF and throttle position
values with other parameters such as TpRE, MAF and MAP. In this manner,
the PPREO estimation provided by the present invention is accurate during post-
calibration engine operation. Alternatively, PPREO can be calculated from a
measured PPRE and calculated air flow velocity using Equation 9.
[0027] Referring now to Figure 3, exemplary steps executed by the
pre-throttle pressure estimation control will be described in detail. In step 300,
control monitors the engine operating parameters including, but not limited to,
MAF, AEFF, TPRE and MAP. In step 302, control calculates fNEW based on the

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engine operating parameters, as described in detail above. Control
determines whether fNEW is greater than or equal to XTHR (e.g., 1.2968) in
step 304. If fNEW is greater than or equal to XTHR, control continues in step
306. If fNEW is not greater than or equal to XTHR, control continues in step
308.
[0028] In step 306, control sets PR equal to 0.528 and f to 0.6847.
Control determines PPREO using Equation 4 in step 309 and control continues
in step 312. In step 308, control determines PR based on fNEW- In step 310,
control determines PPREO based on MAP and PR. Control determines PPRE
based on PPREO in accordance with Equation 9 in step 312, as described in
detail above. In step 314, control regulates engine operation based on PPREO
and PPRE, and control ends.
[0029] Referring now to Figure 4, exemplary steps that are
executed to develop the relationship between AEFF and TPS will be described
in detail. The relationship is determined during dynamometer engine testing.
In step 400, control monitors the engine operating parameters including, but
not limited to, MAF, MAP, TPRE and TPS. In step 402, control calculates
TPREO- Control determines PPREO in step 404. More specifically, PPREO can be
measured using the temporary pressure sensor or can be calculated based
on measured PPRE.
[0030] In step 406, control calculates PR as the ratio of MAP to
PPREO- Control determines whether PR is greater than or equal to 0. 528 in
step 408. If PR is not greater than or equal to 0.528, control sets f equal to
0.6847 in step 410 and continues in step 414. If PR is greater than or equal to
0.528, control calculates f based on Equation 2 in step 412 and continues in
step 414. In step 414, control calculates AEFF for the given TPS using
Equation 1 and control ends.
[0031] Referring now to Figure 5, exemplary modules that execute
the pre-throttle estimation control will be described in detail. The exemplary
modules include a fNEW determining module 500, a comparator module 502,
a PR determining module 504, a PPREo determining module 506, a PPRE
determining module 508 and an engine control module 510. The fNEW

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determining module 500 determines fNEW based on the engine operating
parameters including, but not limited to, MAF, AEFF, TPRE and MAP. The
comparator module 502 compares fNEW to XTHR- If fNEW is less than XTHR,
the comparator module 502 generates a first signal (e.g., 1). If fNEW is not
less than XTHR, the comparator module 502 generates a second signal (e.g.,
0).
[0032] The PR determining module 504 determines PR based on
fNEW and the output signal of the comparator module 502. More specifically,
if the output signal indicates that fNEW is not less than XTHR, the PR
determining module 504 sets PR equal to 0.528. If the output signal indicates
that fNEW is less than XTHR, the PR determining module 504 determines PR
based on fNEW- The PPREO determining module 506 determines PPREO based
on PR and MAP if fNEW is less than XTHR, and based on Equation 4 if fNEW is
not less than XTHR- The PPRE determining module 508 determines PPRE based
on PPREO- The engine control module 510 generates control signals based on
PPREO and PPRE.
[0033] Those skilled in the art can now appreciate from the
foregoing description that the broad teachings of the present invention can be
implemented in a variety of forms. Therefore, while this invention has been
described in connection with particular examples thereof, the true scope of the
invention should not be so limited since other modifications will become
apparent to the skilled practitioner upon a study of the drawings, the
specification and the following claims.

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CLAIMS
What is claimed is:
1. An engine control system for regulating operation of an engine having
a throttle, comprising:
a first module that determines an intermediate parameter based on
engine operating parameters;
a second module that determines a pressure upstream of said throttle
based on said intermediate parameter; and
a third module that regulates operation of said engine based on said
pressure, wherein said operation is regulated based on a pre-determined
relationship between a throttle position and an effective throttle area.
2. The engine control system of claim 1 further comprising a fourth
module that compares said intermediate parameter to a threshold value,
wherein said second module determines said pressure based on said
comparison.
3. The engine control system of claim 1 further comprising a fourth
module that determines a pressure ratio based on said intermediate
parameter.
4. The engine control system of claim 3 wherein said fourth module sets
said pressure ratio equal to a constant value if said intermediate parameter is
not less than a threshold value.
5. The engine control system of claim 3 wherein said fourth module
determines said pressure ratio based on said intermediate parameter if said
intermediate parameter is not less than a threshold value.

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6. The engine control system of claim 1 further comprising:
a fourth module that determines a pressure ratio based on said
intermediate parameter; and
a fifth module that determines a stagnation pressure based on said
pressure ratio.
7. The engine control system of claim 1 wherein said third module
determines whether a component of said engine is functioning properly based
on said pressure.
8. A method of regulating operation of an engine having a throttle,
comprising:
determining an intermediate parameter based on engine operating
parameters;
determining a pressure upstream of said throttle based on said
intermediate parameter; and
regulating operation of said engine based on said pressure, wherein
said operation is regulated based on a pre-determined relationship between a
throttle position and an effective throttle area.
9. The method of claim 8 further comprising comparing said intermediate
parameter to a threshold value, wherein said pressure is determined based
said comparison.
10. The method of claim 8 further comprising determining a pressure ratio
based on said intermediate parameter.
11. The method of claim 10 further comprising setting said pressure ratio
equal to a constant value if said intermediate parameter is not less than a
threshold value.

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12. The method of claim 10 further comprising determining said pressure
ratio based on said intermediate parameter if said intermediate parameter is
not less than a threshold value.
13. The method of claim 8 further comprising:
determining a pressure ratio based on said intermediate parameter;
and
determining a stagnation pressure based on said pressure ratio.
14. The method of claim 8 further comprising determining whether a
component of said engine is functioning properly based on said pressure.
15. A method of regulating operation of an engine having a throttle,
comprising:
determining an intermediate parameter based on engine operating
parameters;
determining a pressure upstream of said throttle based on said
intermediate parameter;
regulating operation of said engine based on said pressure, wherein
said operation is regulated based on a pre-determined relationship between a
throttle position and an effective throttle area; and
diagnosing proper operation of one of said throttle and an engine
sensor based on said pressure.
16. The method of claim 15 wherein said engine sensor includes a mass
air flow sensor.
17. The method of claim 15 further comprising comparing said intermediate
parameter to a threshold value, wherein said pressure is determined based
said comparison.

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18. The method of claim 15 further comprising determining a pressure ratio
based on said intermediate parameter.
19. The method of claim 18 further comprising setting said pressure ratio
equal to a constant value if said intermediate parameter is not less than a
threshold value.
20. The method of claim 18 further comprising determining said pressure
ratio based on said intermediate parameter if said intermediate parameter is
not less than a threshold value.
21. The method of claim 15 further comprising:
determining a pressure ratio based on said intermediate parameter;
and
determining a stagnation pressure based on said pressure ratio.

An engine control system for regulating operation of an engine having
a throttle includes a first module that determines an intermediate parameter
based on engine operating parameters and a second module that determines
a pressure upstream of the throttle based on the intermediate parameter. A
third module regulates operation of the engine based on the pressure. The
engine operation is regulated based on a pre-determined relationship
between a throttle position and ah effective throttle area.

Documents:

00944-kol-2007-abstract.pdf

00944-kol-2007-assignment.pdf

00944-kol-2007-claims.pdf

00944-kol-2007-correspondence others 1.1.pdf

00944-kol-2007-correspondence others 1.2.pdf

00944-kol-2007-correspondence others 1.3.pdf

00944-kol-2007-correspondence others.pdf

00944-kol-2007-description complete.pdf

00944-kol-2007-drawings.pdf

00944-kol-2007-form 1.pdf

00944-kol-2007-form 18.pdf

00944-kol-2007-form 2.pdf

00944-kol-2007-form 3.pdf

00944-kol-2007-form 5.pdf

00944-kol-2007-priority document.pdf

944-KOL-2007-ABSTRACT 1.1.pdf

944-KOL-2007-AMANDED CLAIMS.pdf

944-KOL-2007-AMANDED PAGES OF SPECIFICATION.pdf

944-KOL-2007-CORRESPONDENCE 1.4.pdf

944-KOL-2007-CORRESPONDENCE-1.5.pdf

944-KOL-2007-CORRESPONDENCE.1.3.pdf

944-KOL-2007-DESCRIPTION (COMPLETE) 1.1.pdf

944-KOL-2007-DRAWINGS 1.1.pdf

944-KOL-2007-EXAMINATION REPORT REPLY RECIEVED.pdf

944-KOL-2007-EXAMINATION REPORT.1.3.pdf

944-KOL-2007-FORM 1-1.1.pdf

944-KOL-2007-FORM 18.1.3.pdf

944-KOL-2007-FORM 2-1.1.pdf

944-KOL-2007-FORM 26.1.3.pdf

944-KOL-2007-FORM 26.pdf

944-KOL-2007-FORM 3-1.1.pdf

944-KOL-2007-FORM 3.1.3.pdf

944-KOL-2007-FORM 5.1.3.pdf

944-KOL-2007-FORM-27.pdf

944-KOL-2007-GRANTED-ABSTRACT.pdf

944-KOL-2007-GRANTED-CLAIMS.pdf

944-KOL-2007-GRANTED-DESCRIPTION (COMPLETE).pdf

944-KOL-2007-GRANTED-DRAWINGS.pdf

944-KOL-2007-GRANTED-FORM 1.pdf

944-KOL-2007-GRANTED-FORM 2.pdf

944-KOL-2007-GRANTED-LETTER PATENT.pdf

944-KOL-2007-GRANTED-SPECIFICATION.pdf

944-KOL-2007-OTHERS.1.3.pdf

944-KOL-2007-OTHERS.pdf

944-KOL-2007-PETITION UNDER RULE 137.pdf

944-KOL-2007-REPLY TO EXAMINATION REPORT.1.3.pdf


Patent Number 247729
Indian Patent Application Number 944/KOL/2007
PG Journal Number 19/2011
Publication Date 13-May-2011
Grant Date 09-May-2011
Date of Filing 29-Jun-2007
Name of Patentee GM GLOBAL TECHNOLOGY OPERATIONS, INC.
Applicant Address 300 GM RENAISSANCE CENTER, DETROIT, MICHIGAN
Inventors:
# Inventor's Name Inventor's Address
1 WENBO WANG 25831 TRESTLE STREET, NOVI MICHIGAN 48375
2 KURT D. MC LAIN 8020 TIY ANOGA TRAIL, CLARKSTON, MICHIGAN 48348 UNITED STATES OF AMERICA
3 MICHAEL A. KROPINSKI 1530 HAMMAN DRIVE, TROY, MICHIGAN, 48085
PCT International Classification Number F02D41/18
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 11/464340 2006-08-14 U.S.A.