ISSN: 1693-6930
TELKOMNIKA
Vol. 10, No. 1, March 2012 : 83 – 90 84
There are several methods in application of engine torque control, i.e. by regulating ignition time, air-to-fuel ratio, and throttle position. In [9] and [10] was performed engine torque
control by regulating ignition time, this strategy done well in fuel saving but not give maximum results in engine torque tracking. Similarly, in [11] was performed engine torque control by
regulating air-to-fuel ratio, the results obtained is also not optimal in engine torque tracking.
This paper focuses in particular on engine torque control by regulating throttle position and maintains air-to-fuel ratio and time ignition as close as possible to ideally yield perfect
combustion. The goal is to develop algorithms which can control engine torque well, thus providing adequate fuel control and driving convenience to driver. One way to potentially meet
these performance requirements is to introduce a method of controlling engine torque using fuzzy gain scheduling, since many fuzzy application have been developed in engine and vehicle
performance development [5], [9]–[12]. By using this method, the throttle opening commanded by the driver will be corrected by throttle correction signal that guarantees engine torque output
will follow the desired engine torque input. In this case, spark ignition engine with automatic transmission is used to meet a good performance under this controller design.
2. Spark Ignition Engine with Automatic Transmission
In this research, we use spark ignition engine model as described in [13]. The model is Ford SI-engine model.
The rate of air into the intake manifold can be expressed as the product of two functions; i.e. an empirical function of the throttle plate angle and a function of the atmospheric
and manifold pressures, as shown in Equation 1.
ai
m =
2 1
m
P f
f
θ
1 where
ai
m = mass flow rate into manifold gs, with
1
θ
f =
3 2
00063 .
10299 .
05231 .
821 .
2 θ
θ θ
− +
− θ
= throttle angle deg
2
Pm f
=
≥ −
≤ ≤
− −
≤ ≤
− ≤
amb m
amb m
amb m
amb m
m amb
m amb
m amb
m amb
amb m
P P
P P
P P
P P
P P
P P
P P
P P
P P
2 2
, 1
2 ,
2 2
, 2
2 ,
1
2 2
m
P = manifold pressure bar
amb
P = ambient atmospheric pressure bar, 1 bar
The intake manifold can be modeled as a differential equation for the manifold pressure, as shown in Equation 2.
m
P
=
ao ai
m
m m
V RT
−
=
ao ai
m m
− 0.41328
2 where
R = specific gas constant
T = temperature
o
K V
m
= manifold volume m
3
ao
m
= mass flow rate of air out of the manifold gs
m
P
= rate of change of manifold pressure bars, with P = 0.543 bar
TELKOMNIKA ISSN: 1693-6930
Engine Torque Control of Spark Ignition Engine using Fuzzy Gain …. Aris Triwiyatno 85
The mass flow rate of air that the model pumps into the cylinders from the manifold is described in Equation 3 by an empirically derived equation.
ao
m
=
m m
m
P N
NP NP
2 2
0001 .
0337 .
08979 .
366 .
+ −
+ −
3 where
ao
m
= mass flow rate of air out of the manifold gs N
= engine speed rads P
m
= manifold pressure bar The torque developed by the engine is described as in Equation 4.
e
T
=
2 2
0028 .
26 .
85 .
91 .
21 36
. 379
3 .
181 σ
σ − +
− +
+ −
F A
F A
m
a a
a
m m
N N
N
2 2
05 .
55 .
2 00048
. 000107
. 027
. σ
σ σ
− +
+ −
+
4 where
a
m
= mass of air in cylinder for combustion g F
A = air to fuel ratio
σ
= spark advance degrees before top-dead-centerTDC
e
T = torque produced by the engine Nm
Fuel consumption can be estimated with air-to-fuel ratio estimation AF and mass of air in cylinder for combustion m
a
≈
m
ao
in Equation 3; as shown in Equation 5. Fuel
=
F A
m
a
5 where
Fuel
= fuel consumption g
a
m
= mass of air in cylinder for combustion g
F A
= air to fuel ratio The engine torque less the impeller torque results in engine acceleration; as in
Equation 6.
N I
ei
=
L e
T T
−
6 where
ei
I
= engine rotational + impeller moment of inertia kg-m
2
= 0.14 kg-m
2
N
= engine acceleration rads
2
, with initial engine speed N = 209.48 rads
e
T
= torque produced by the engine Nm
L
T
= load torque Nm Load torque
L
T
generally produced by vehicle dynamics. The vehicle model with 4- step automatic gear transmission that used in this engine model application is derived based on
state-flow model as in [13].
3. Engine Torque Management Strategy
