View source for LAMFAW 7.100 (Driver's Requested Lambda)

See the ''funktionsrahmen'' for the following diagrams:

lamfaw-lamfaw
 
lamfaw-lamkr
 
lamfaw-lamwl

lamfaw-lamfadisable
 
lamfaw-lamrlmin
 
lamfaw-initialise

  
<u>Function Description</u>

The function LAMFAW brings about an enrichment of the fuel-air mixture via lamfa_w when the driver demands maximum torque via mrfa_w. This then corresponds to the full-load enrichment. The intervention to the mixture via lamfa_w can be delayed via the delay time TLAFA. During turbocharger overboost, an additional enrichment is applied by a delta-lambda from the characteristic DLAMOB.

  
For the time TLAMFAS, an enrichment via the driver’s request as a function of altitude (LAMFAS) can be prevented (see sub-function LAMFADISABLE). Triggering of this time will be initiated if B_kh = true, LAMFA &lt;1.0 and the altitude at which the function is disabled (as defined in LAMFAS) has been reached.

  
In this way, a reproducible driving cycle can also be achieved at higher altitudes.

During a torque reduction, e.g. traction control intervention, engine speed limiter, etc. the enrichment via the map LAMFAW can be disabled by setting CWMFAW Bit 1 = true.

 
In the sub-function LAMKR, an enrichment can be implemented during ignition angle intervention.
 
The sub-function LAMWL can be used for the enrichment during warm-up. If this procedure is used, tank-venting via the function LAMKO is not switched off.

 
In the sub-function LAMRLMIN, an enrichment via LAMRLMN is active for low loads (rl). This improves the combustion efficiency at low loads. If CWLAMFAW bit 2 is set, then the emergency fuel tank breather is disabled during lamrlmn-intervention.

  
<u>Application Notes</u>

A delay time TLAFA &gt; 0 can only be applied when the mixture intervention via lamfa_w should be delayed.

  
Map LAMFA:

  
Engine speed sample points: 1000, 1400, 1800, 2200, 2600, 3000, 3400, 3800, 4200, 4600, 5000, 5400, 5800, 6200, 6600, 7000 rpm

mrfa_w sample points: 70, 80, 90, 100, 110, 120 %

Map values of 1.0

  
DLAMOB comprises the delta-lambda, so that an additional mixture enrichment is implemented in overboost mode.

Sample points for engine speed: implemented as a group characteristic SNM06GKUB

Neutralization of the function by data:

LAMFA = 1.0 and DLAMOB = 0.0 ---> lamfa_w is then 1.0

The time TLAMFAS must be selected so that no large gradients are caused in the driver’s requested enrichment (typically 240 s).

  
The characteristic LAMFAS contains values &#8203;&#8203;from 0 to 1. If the value is 0, enrichment via the altitude effect is active. Values &#8203;&#8203;other than 0 deactivate enrichment via LAMFA, if B_kh = true and LAMFA values &#8203;&#8203;are &lt; 1.0.

 
The characteristic LAMFAS is not interpolated, which means that the characteristic initial value remains constant until a node is crossed.

  
For the fho-sample points of the characteristic LAMFAS, the following relationship applies: fho = 1
– altitude [m]/10,000 m

 
Since the variable fho has a quantization of 4/256 = 0.015625, this resolution must be considered when determining the switch-off. Similarly, there is a potential altitude deviation of ± 250 m because of the sensor tolerance.

  
For the calculation of the lower or upper threshold of fho, the following relationship applies for a nominal altitude cut-off threshold:

  
<u>Lower altitude cut-off threshold:</u>

fho [phys] = 1 – ((nominal altitude [m] – 250 m ) /10,000)

---> fho[Ink] = Integer (fho[phys]/0.015625) + 1Ink

---> fho upper limit [phys] = (1 – fho[Ink] x 0.015625)

---> Altitude upper limit = (1 – fho upper limit [phys]) x 10,000

  
<u>Upper altitude cut-off threshold:</u>

fho [phys] = 1 – ((nominal altitude [m] + 250 m)/10,000)

---> fho[Ink] = Integer (fho[phys]/0.015625)

---> fho lower limit [phys] = fho[Ink] x 0.015625

---> Altitude lower limit = (1 – fho lower limit [phys]) x 10,000

 
This produces the following values:
                                 
{| border="1"
|-
| 
Nominal
altitude 
| 
2,200 m 
| 
1,600 m 
|  
|-
| 
Altitude
upper limit
| 
2,500 m
| 
1,875 m
| 
The altitude upper limit is the fho lower limit!
|-
| 
fho lower limit
| 
0.75
| 
0.8125
|-
| 
Altitude lower limit
| 
1,875 m
| 
1,250 m
|  
|-
| 
fho upper limit 
| 
0.8125
| 
0.875
|  
|}


Thus, the characteristic LAMFAS is parameterized as follows for the nominal altitude of 2,200 m:

                      
{| border="1"
|-
| 
fho
| 
0.734375
| 
0.7500
| 
0.8125
|-
| 
Value
| 
0
| 
1
| 
0 
|-
|  
| 
Enrichment active 
| 
Enrichment inactive 
| 
Enrichment active 
|}


Switching off the altitude-dependent enrichment suppression: LAMFAS = 0, TLAMFAS = 0

  
Values for lambda intervention lamfawkr_w during ignition angle retardation:

  
ZKLAMFAW: 2 s
 
ZKWLAFWL: 2 s
 
DLAMFAW: 0.01
 
KFLAMKR: Engine speed sample points: Group characteristic SNM06GKUB
rl sample points: Group characteristic SRL06GKUB
Map values: All are 1.0 ---> no weighting active

KFLAMKRL: dzlamfaw sample points: Group characteristic SDZ0 6GKUB
rl sample points: Group characteristic SRL06GKUB
Map values: All are 1.0 ---> lambda intervention not active

DLAMTANS: Ambient temperature sample points: 50.25, 60, 70.5, 80.25 °C
Map values: All are 0 ---> lambda intervention not active

KFLAFWL: Engine speed sample points: Group characteristic SNM06GKUB
rl sample points: Group characteristic SRL06GKUB
Map values: All are 0 ---> lambda intervention not active
''In the map, delta values are entered, –0.1 ''''--->'' '' lamfwl_w = 0.9!''

DLAMOB: Engine speed sample points: Group characteristic SNM06GKUB
Map values: All are 0 ---> no additional enrichment during overboost
''In the map, delta values are entered + 0.1 ''''--->'' ''lamfa = lamfaw – 0.1!''

RLLAMMN: Engine speed sample points: Group characteristic SNM06GKUB
Map values: 0% ---> enrichment via LAMRLMN not active

LAMRLMN: Engine speed sample points: Group characteristic SNM06GKUB
Map values: 1.0 ---> lambda = 1.0 (no enrichment)


CWLAMFAW Bit 0: 0: dzwlamfaw = min (0, dzwwl)

1: dzwlamfaw = min (0, (dzwwl + wkrma)). Default value = 0.


CWLAMFAW Bit 1: 0: LAMFAW also during torque reduction, e.g. via traction control, engine speed limiter, etc. active

1: no enrichment via LAMFAW during torque reduction (milsol &lt; mifa)

 
CWLAMFAW Bit 2: 0: B_ldeffw is always false ---> emergency fuel tank breather also during lamrlmn_w-intervention active

1: B_ldeffw dependent on lamrlmn_w-activation, when B_ldeffw = true, emergency fuel tank breather disabled, i.e. fuel tank breather valve shuts.

 
CWLAMFAW Bit 3: 0: Disable driver’s requested lambda activation through catalyst heating enabled

1: Disable driver’s requested lambda activation through catalyst heating not possible


CWLAMFAW Bit 4: 0: lamfwl_w dependent on B_stend and VZ1-term

1: lamfwl_w not dependent on B_stend and VZ1-term

  
Group characteristic for engine speed sample points: SNM06GKUB: 760, 1520, 2560, 3520, 4560, 5520 rpm
 
Group characteristic for relative load sample points: SRL06GKUB: 20, 40, 60, 80, 90 %
 
Group characteristic for engine temperature sample points: STM0 8GKUB: –15, 0, 20, 40.5, 60, 75, 85.5, 105 °C

Group characteristic for dzwlamfaw sample points: SDZ06GKUB: –30, –20, –15, –10, –5, 0 degrees

{| border="1"
|-
| 
'''Parameter'''
| 
'''Description''' 
|-
| 
CWLAMFAW 
| 
Codeword LAMFAW
|-
| 
DLAMFAW
| 
Threshold value for activating enrichment via driver’s request
|-
| 
DLAMOB
| 
Delta lambda during overboost
|-
| 
DLAMTANS
| 
Air temperature-dependent enrichment
|-
| 
GANGFAW
| 
Gear
threshold for deactivating driver’s request at altitude
|-
| 
KFLAFWL
| 
Offset engine target lambda
|-
| 
KFLAMKR
| 
Weighting factor for enrichment during ignition angle retardation
|-
| 
KFLAMKRL
| 
Enrichment
during ignition angle retardation
|-
| 
LAMFA
| 
Driver’s requested lambda
|-
| 
LAMFAS
| 
Disable driver’s requested lambda
|-
| 
LAMRLMN
| 
Lambda
control when rl &lt; RLLAMMN to improve the combustion efficiency
|-
| 
RLLAMMN
| 
Minimum requested load threshold for enrichment due to combustion efficiency
|-
| 
SDZ06GKUB
| 
Sample point distribution for KFLAMKRL
|-
| 
SNM06GKUB
| 
Sample
point distribution for KFLAMKR, DLAMOB
|-
| 
SRL06GKUB
| 
Sample point distribution for KFLAMKRL, KFLAFWL, KFLAMKR
|-
| 
STM08GKUB
| 
8 engine
temperature sample point distribution for KFLAFWL
|-
| 
SY TURBO
| 
System constant: turbocharger
|-
| 
TLAFA
| 
Delay time with driver’s requested lambda active
|-
| 
TLAMFAS
| 
Delay time with driver’s requested lambda at altitude active
|-
| 
TMSTFWMN
| 
Minimum
engine start temperature for deactivating driver’s request at altitude
|-
| 
TMSTFWMX
| 
Maximum
engine start temperature for deactivating driver’s request at altitude
|-
| 
TNSTFWMN
| 
Minimum
time after start for deactivating driver’s request at altitude
|-
| 
TNSTFWMX
| 
Maximum
time after start for deactivating driver’s request at altitude
|-
| 
ZKLAMFAW
| 
Time
constant filtering enrichment via driver’s request
|-
| 
ZKWLAFWL
| 
Time
constant weighting offset engine target lambda
|-
| 
'''Variable'''
| 
'''Description'''
|-
| 
B_KH
| 
Condition flag: catalyst
heating
|-
| 
B_LAMFAS
| 
Condition
flag: disable driver’s requested lambda
|-
| 
B_LAMFASA
| 
Condition
flag: altitude-dependent disabling time for driver’s requested lambda is
required
|-
| 
B_LAMFASH
| 
Condition
flag: altitude-dependent disabling time for driver’s requested lambda is active
|-
| 
B_LDEFFW
| 
Condition
flag: defined target lambda (cylinder bank 1) via driver’s request
|-
| 
B_LDOB
| 
Condition flag: overboost
active
|-
| 
B_SAB
| 
Condition
flag: overrun fuel cut-off readiness
|-
| 
B_STEND
| 
Condition
flag: end of start conditions reached
|-
| 
DZWLAMFAW
| 
Delta
ignition angle during knock control intervention or warm-up for enrichment
via lambda
|-
| 
DZWWL
| 
Delta ignition angle during warm-up
|-
| 
FHO
| 
Altitude correction factor
|-
| 
GANGI
| 
Actual gear
|-
| 
LAMFAWKR_W
| 
Driver’s requested target lambda during ignition angle retardation (knock control), WL
|-
| 
LAMFAWS W
| 
Driver’s requested target lambda steady-state part
|-
| 
LAMFAW_W
| 
Driver’s requested target lambda part from map LAMFA
|-
| 
LAMFA_W
| 
Driver’s requested target lambda (word)
|-
| 
LAMFWL_W
| 
Offset engine target lambda during warm-up
|-
| 
LAMRLMN_W
| 
Target lambda control to improve the combustion efficiency at lower relative loads
|-
| 
MIFA_W
| 
Indexed driver’s requested engine torque
|-
| 
MILSOL_W
| 
Driver’s requested torque for cylinder charge path
|-
| 
MRFA_W
| 
Relative driver’s requested torque from cruise control and throttle pedal
|-
| 
NMOT
| 
Engine speed
|-
| 
RL
| 
Relative cylinder charge
|-
| 
TANS
| 
Ambient air temperature
|-
| 
TMOT
| 
Engine temperature
|-
| 
TMST
| 
Engine start temperature
|-
| 
TNST_W
| 
Time after end of start conditions
|-
| 
WKRMA
| 
Average
value of the individual cylinder ignition angle retardation (knock control), general (in emergency mode with safety margin)
|}                                                                                                   

[[Category:ME7]]