Systems and methods for estimating residual gas fraction for internal combustion engines using altitude compensation
View Patent ↗An engine control system comprises a first factor calculating module that calculates a first factor based on intake cam position (ICAM), exhaust cam position (ECAM), engine speed (RPM) and first calibration factors. A second factor calculating module calculates a second factor based on ICAM, ECAM, RPM and second calibration factors. A residual gas fraction (RGF) estimating module estimates a RGF value based on the first factor adjusted for altitude and said second factor. A method comprises calculating a first factor based on intake cam position (ICAM), exhaust cam position (ECAM), engine speed (RPM) and first calibration factors; calculating a second factor based on ICAM, ECAM, RPM and second calibration factors; and estimating a residual gas fraction (RGF) value based on the first factor adjusted for altitude and said second factor. At least one engine operating parameter is adjusted based on the RGF value.
1. An engine control system, comprising:
a first factor calculating module that calculates a first factor based on intake cam position (ICAM), exhaust cam position (ECAM), engine speed (RPM) and first calibration factors;
a second factor calculating module that calculates a second factor based on ICAM, ECAM, RPM and second calibration factors;
a residual gas fraction (RGF) estimating module that estimates a RGF value based on said first factor adjusted for altitude and said second factor; and
an engine operating module that adjusts at least one engine operating parameter based on said RGF value.
2. The engine control system of claim 1 wherein said first factor calculating module calculates said first factor based on:
A (ICAM,ECAM,RPM)= a 0 +a 1 ICAM+ a 2 ECAM+ a 3 RPM+ a 4 ICAM*ECAM+ a 5 ICAM*RPM+ a 6 ECAM*RPM+ a 7 ICAM 2 +a 8 ECAM 2 +a 9 RPM 2
wherein a 0 , a 1 , . . . a 9 are said first calibration factors.
3. The engine control system of claim 1 wherein said second factor calculating module calculates said second factor based on:
B (ICAM,ECAM,RPM)= b 0 +b 1 ICAM+ b 2 ECAM+ b 3 RPM+ b 4 ICAM*ECAM+ b 5 ICAM*RPM+ b 6 ECAM*RPM+ b 7 ICAM 2 +b 8 ECAM 2 +b 9 RPM 2
wherein b 0 , b 1 , . . . b 9 are said second calibration factors.
4. The engine control system of claim 1 wherein said RGF estimating module estimates said RGF value based on
RGF
=
A
(
I
C
A
M
,
E
C
A
M
,
R
P
M
)
P
baro
M
A
P
+
B
(
I
C
A
M
,
E
C
A
M
,
R
P
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)
wherein P baro is barometric pressure and MAP is manifold absolute pressure.
5. The engine control system of claim 1 wherein P baro is estimated.
6. The engine control system of claim 1 wherein P baro is periodically sensed during operation.
7. The engine control system of claim 1 wherein said engine operating module calculates at least one of charge mass, dilution, temperature and flame speed based on said RGF value.
8. The engine control system of claim 1 wherein said engine operating module adjusts at least one of engine idle speed, fuel and/or throttle based on said RGF value.
9. The method of claim 1 further comprising adjusting at least one of engine idle speed, fuel and/or throttle based on said RGF value.
10. A method comprising:
calculating a first factor based on intake cam position (ICAM), exhaust cam position (ECAM), engine speed (RPM) and first calibration factors;
calculating a second factor based on ICAM, ECAM, RPM and second calibration factors;
estimating a residual gas fraction (RGF) value based on said first factor adjusted for altitude and said second factors; and
adjusting at least one engine operating parameter based on said RGF value.
11. The method of claim 10 wherein said first factor is based on:
A (ICAM,ECAM,RPM)= a 0 +a 1 ICAM+ a 2 ECAM+ a 3 RPM+ a 4 ICAM*ECAM+ a 5 ICAM*RPM+ a 6 ECAM*RPM+ a 7 ICAM 2 +a 8 ECAM 2 +a 9 RPM 2
wherein a 0 , a 1 , . . . a 9 are said first calibration factors.
12. The method of claim 10 wherein said second factor is based on:
B (ICAM,ECAM,RPM)= b 0 +b 1 ICAM+ b 2 ECAM+ b 3 RPM+ b 4 ICAM*ECAM+ b 5 ICAM*RPM+ b 6 ECAM*RPM+ b 7 ICAM 2 +b 8 ECAM 2 +b 9 RPM 2
wherein b 0 , b 1 , . . . b 9 are said second calibration factors.
13. The method of claim 10 wherein said RGF value is based on
R
G
F
=
A
(
I
C
A
M
,
E
C
A
M
,
R
P
M
)
P
baro
M
A
P
+
B
(
I
C
A
M
,
E
C
A
M
,
R
P
M
)
wherein P baro is barometric pressure and MAP is manifold absolute pressure.
14. The method of claim 10 further comprising estimating P baro .
15. The method of claim 10 further comprising periodically sensing P baro during operation.
16. The method of claim 10 wherein said engine operating module calculates at least one of charge mass, dilution, temperature and flame speed based on said RGF value.