Difference between revisions of "MDBAS 8.30 (Calculation of the Basic Parameters for the Torque Interface)"
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Revision as of 15:09, 29 September 2011
MDBAS 8.30 Function Description
See the funktionsrahmen for the following diagrams:
MDBAS
MDBAS (included in this translation)
MDBAS
ZW NWS
The
optimum torque values mioptl1_w at lambda = 1 are calculated with the help of
the map KFMIOP. This torque is corrected for the influence of lambda by
multiplying by the lambda efficiency (etalab). The lambda efficiency is obtained
from the characteristic line ETALAM. Multiplying by the ignition angle
efficiency gives the basic torque mibas. This corresponds to the indicated
torque that is set when the combustion takes place with the basic lambda (lambas)
and the base ignition angle (zwbas).
The
optimum ignition angle at lambda = 1 is determined from the map KFZWOP. The
sub-function ZW_NWS describes the influence on the optimum ignition angle of an
existing camshaft timing adjustment. The equipment options are none, binary (on
or off), or continuously variable camshaft timing adjustment. In the case of
binary adjustment, the factor fnwue governs continuous switching between the
maps KFZWOP and KFZWOP2. In the case of continuous camshaft timing adjustment
which depends on the camshaft overlap angle (wnwue) an ignition angle
correction is added to KFZWOP. The determined optimum ignition angle (zwoptl1) again
applies for lambda = 1. The currently applicable camshaft timing adjustment type
is defined by the system constant SY_NWS in SW generation:
SY_NWS
= 0: no camshaft timing adjustment
SY_NWS
= 1: binary camshaft timing adjustment
SY_NWS
= 2: continuously variable camshaft timing adjustment
SY_NWS > 2: not defined.
The
software is translated conditionally, i.e. there is only one variant in the
EPROM. SY_NWS is not in the EPROM and can not be applied.
Additive
corrections depending on lambda, the exhaust gas recirculation rate and engine
temperature are included. The resulting ignition angle (zwopt) now forms the
basis for the ignition angle efficiency calculation. The basic ignition angle
efficiency is calculated using the characteristic ETADZW, the input value is obtained
from the difference between zwopt and zwbas. This is followed by an averaging
of the basic efficiencies across all cylinders and the result is the base
efficiency etazwbm.
The
ignition angle correction for exhaust gas recirculation operation can through the
code word CWMDBAS either always be included or only included if B_agr = true.
In the case of permanent inclusion, ignition angle jumps are avoided by
switching off B_agr.
MDBAS 8.30 Application Notes
Exhaust
gas recirculation should be inactive throughout all these measurements! Data
input requires the following measurements to be made:
1.
Operation at Lambda = 1:
Ignition
angle fine tuning on an engine dynamometer at lambda = 1 with the engine at
normal operating temperature at the following operating points:
Engine
speed = 500, 750, 1000, 1250, 1500, 2000, 2500, 3000, 3500, 4000, 4500, 5000, 5500,
6000 & 6500 rpm (if possible)
Relative
cylinder charge = 10, 20, 30, 40, 50, 60, 70, 80, 90 and 100%
Ignition
angle fine turning begins at the ignition angle at which maximum torque is
achieved (i.e. maximum brake torque, MBT) if not to drive at the knock limit. The
ignition angle should now be retarded in steps of 4.5° crank angle until the latest mobile firing angle is
achieved. The following data must be recorded at each point: engine speed (nmot),
relative cylinder charge (rl), lambda, clutch torque and ignition angle.
2. Lambda Dependence
Ignition
angle fine tuning through lambda at the following measuring points:
Engine
speed = 1000, 2000, & 3000 rpm
Relative
cylinder charge = 30, 50 & 70 %
Lambda = 0.80, 0.85, 0.90, 0.95, 1.00, 1.05, 1.10,
1.15 & 1.20
Measurements
as above.
3.
Drag Torque
The
drag torque (engine braking) must be obtained at all the measuring points
specified in 1. Measure on an engine dynamometer with no ignition and with the engine
at its normal operating temperature.
4. Evaluation
Evaluation
of the results takes place at K3/ESY4-Hes.
Parameter
|
Description
|
AGRRMAX
|
Maximum possible exhaust gas recirculation rate
|
CWMDBAS
|
Codeword to take account of the ignition angle correction for exhaust gas recirculation operation
|
DZWNWSUE
|
Delta ignition angle depending on camshaft angle
|
DZWOLA
|
Lambda dependence of the optimum ignition angle relative to lambda = 1
|
DZWOM
|
Temperature dependent offset of the optimum ignition angle
|
ETADZW
|
Ignition angle efficiency dependence on delta ignition angle
|
ETALAM
|
Lambda efficiency
|
KFDZWOAGR
|
Offset of the optimum ignition angle with exhaust gas recirculation operation
|
KFMIOP
|
Optimum engine torque map
|
KFZWOP
|
Optimum ignition angle
|
KFZWOP2
|
Optimum ignition angle variant 2
|
Variable
|
Description
|
AGRR
|
Exhaust gas recirculation rate
|
B_AGR
|
Exhaust gas recirculation one condition
|
DZWOAG
|
Exhaust gas recirculation rate dependent ignition angle correction of the optimum ignition angle
|
DZWOL
|
Lambda dependent ignition angle correction of the optimum ignition angle
|
DZWOTM
|
Temperature dependent ignition angle correction of the optimum ignition angle
|
ETALAB
|
Lambda efficiency without intervention based on optimum torque at lambda
|
ETATRMN
|
Minimum value of the cylinder barrel efficiency
|
ETAZWB
|
Ignition angle efficiency of the basic ignition angles
|
ETAZWBM
|
Mean ignition angle efficiency of the basic ignition angles
|
FNWUE
|
Weighting factor for inlet camshaft overlap
|
LAMBAS
|
Basic lambda
|
MIBAS_W
|
Indicated basic torque
|
MIOPTL1_W
|
Optimum indicated torque at lambda = 1
|
MIOPT_W
|
Optimum indicated torque
|
NMOT W
|
Engine speed
|
RL_W
|
Relative cylinder charge (word)
|
R_SYN
|
Synchro-raster
|
SY_NWS
|
System constant for camshaft control: none, binary (on/off) or continuous
|
TMOT
|
Engine (coolant) temperature
|
WNWUE
|
Camshaft overlap angle
|
ZWBAS
|
Basic ignition angle
|
ZWOPT
|
Optimum ignition angle
|