Difference between revisions of "LDRLMX 3.100 (Calculation of LDR Maximum Cylinder Charge rlmax)"

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The low pass of the long-term component is active only above a speed-dependent load threshold RLKRLDA that is representative for fuel adaption. The characteristic field KFFLLDE sets the steady-state reduction.
 
The low pass of the long-term component is active only above a speed-dependent load threshold RLKRLDA that is representative for fuel adaption. The characteristic field KFFLLDE sets the steady-state reduction.
 
    
 
    
The low pass of the short-term component works with the difference of the filtered long-term average value (wkrmstat) and the actual average value (wkrma). To avoid interference of opposing interventions from both the aforementioned components, the minimum difference is limited to zero.
+
The low pass of the short-term component works with the difference of the filtered long-term average value (wkrmstat) and the actual average value (wkrma). To avoid conflicting interventions from both the aforementioned components, the minimum difference is limited to zero.
 
   
 
   
 
The associated drawdown value is determined by KFFSLDE.
 
The associated drawdown value is determined by KFFSLDE.

Revision as of 04:15, 29 January 2012

See the funktionsrahmen for the following diagrams:

ldrlmx-main LDRLMX function definition

ldrlmx-fldrrx

ldrlmx-sstb

ldrlmx-set

ldrlmx-rlmx-w

ldrlmx-tsel

ldrlmx-frxta-w

ldrlmx-hierarchy

ldrlmx-initialise


LDRLMX 3.100 Function Description

The function LDRLMX calculates the allowed maximum cylinder charge.

In the main path, the maximum charge value dependent on engine speed is given by the characteristic LDRXN. This can be corrected, if necessary, through intervention of the workshop tester.


For this purpose, an additive overboost increase (drlmaxo, delta maximum cylinder charge during overboost) is applied via the knock-control intervention.


On the rlmx path, a multiplicative correction is applied via the characteristic field KFTARX as a function of engine speed and intake air temperature.


Subsequently, there is an intervention via the sub-function FLDRRX as a function of the average ignition angle retardation in knock control (wkrma). This function consists of two parts, a quasi-steady state long-term component (permanent RAM) which takes the fuel octane rating into account, and a dynamic short-term component to take all other perturbations into account.

The low pass of the long-term component is active only above a speed-dependent load threshold RLKRLDA that is representative for fuel adaption. The characteristic field KFFLLDE sets the steady-state reduction.

The low pass of the short-term component works with the difference of the filtered long-term average value (wkrmstat) and the actual average value (wkrma). To avoid conflicting interventions from both the aforementioned components, the minimum difference is limited to zero.

The associated drawdown value is determined by KFFSLDE.

The overboost path is corrected separately, by a dependence on the sum of both low-pass outputs (wkrmsu) and the speed of the associated drawdown is determined via KFFLDEO.

The time constants of the two components are each separated into predetermined up-regulating and down-regulating speed dependencies.

Further on down the main pathway, the maximum cylinder charge is limited by an external pressure dependency to avoid overloading the turbocharger at high altitudes.

This limit (maximum compressor pressure ratio) which is engine speed and tsel (tans/tumc)-dependent is determined via KFLDHBN, by multiplying the external pressure by the maximum absolute pressure and then using pirg_w and fupsrl_w to convert to a cylinder charge level.

When an ambient temperature sensor is present, the map KFLDHBN is addressed with the ambient temperature through the system constant SY_TFUMG and CWRLMX = 1 and to the instrument cluster via CAN. If no ambient temperature sensor is available or CWRLMX = 0, the map KFLDHBN is addressed with tans.

Via the system constants SY_TFMO, SY_GGGTS the oil temperature (toel) or the cooling water temperature from the instrument cluster (tmki) are read by sensors, whose signal is evaluated in functions %GGTOL or %GGGTS. If the respective variables are available via the CAN (tolc or tmkic) then switching to the CAN-variables will occur or, in case of failure, to surrogate values​​.

If a system failure is detected, an additional engine speed dependent (pressure) limitation (LDPBN) comes into force, which is analogous to the altitude limitation on the cylinder charge level. Switching back only occurs when resetting the tripping fault and in idle mode (B_ll).

In the overboost condition (E_ldo) an engine speed dependent limit (LDORXN) is switched in so that both the engine and the turbocharger adequately protected. Switching back also occurs only when resetting the error (E_ldo) and in idle-mode (B_ll).


LDRLMX 3.100 Application Notes

[B]LDRXN[/B]: It must be ensured that even at speeds below the turbocharger response speed meaningful rlmax-values ​​(about 10% above the value of throttle plate at full open test bench) can be specified. Above the turbocharger response speed, the regular allowable and desired rlmax values ​​are defined in this characteristic.

[B]LDORXN[/B]: maximum allowable cylinder charge, such that there is sufficient protection by an appropriately strong throttling of the throttle and turbocharger. (Remove the wastegate pressure hose during application!)

[B]LDPBN[/B]: pressure relief in case of diagnosis (sudden torque drop should be no larger than about 15%).

[B]KFLDHBN[/B]: Firstly, in the compressor performance map, acquire the regular full load line at speed sample points ​​ of KFLDHBN as well as the maximum pressure ratio line (due to the surge limit, maximum turbocharger-speed or prohibited areas of poor efficiency) to define the operational limit.

Then one carries on the height gradients from the normal full load line starting, at any engine speed, up to an operating limit.

This increases with increasing altitude (decreasing ambient pressure) of the volume flow rate and the pressure ratio with 1013/ambient pressure.

This new intersection then defines the maximum pressure ratio for KFLDHBN at the respective engine speed.

Attention! It must be ensured through appropriate application of RLKRLDA and LDRXN that the operating range of the long-time filter (rl > RLKRLDA) can always be reached! Otherwise, it might happen that a very large decrease will be locked in the long-term component itself and no new adaptation can take place.

All other values ​​are highly dependent on the project.

Basic data input

ATTENTION applicators, these data are extremely project-specific and must be verified in each project application! Please note carefully or risk engine damage! In order to achieve the same functionality as in LDRLMX 3.70 in the absence of CAN message from the instrument cluster, note the following.


SY_TFMO

SY_GGGTS

Remark

0

0

FKRXTOL and KFFKRXTM set = 1 >= frxt = 1

1

0

FKRXTOL set to a maximum value >= frxt = output KFFKRXTM

0

1

KFFKRXTM set to a maximum value >= frxt = output FKRXTOL


LDRXN: 140%

LDORXN: 15%

LDPBN: 1500 mbar

KFLDHBN: from low engine speed 1.9 to medium engine speed (2500 rpm) constant 2.5

FKRXTOL: 1.0 (1.0 does not limit the boost pressure control)

KFFKRXTM: 1.0 (1.0 does not limit the boost pressure control)

KFFLDEO: 1.0 (1.0 does not limit the boost pressure control)

KFFSLDE: 1.0 (1.0 does not limit the boost pressure control)

KFFLLDE: 1.0 (1.0 does not limit the boost pressure control)

KFFWLLDE: 1.0 (1.0 does not limit the boost pressure control)

KFTARX: data values of 1.0 below IAT of 75°C. Data values linearly reduced from 1.0 to 0.8 between 75°C and 120°C)

KFTARXZK: about 10% less than KFTARX

LDRXNZK: about 15% less than LDRXN

RLKRLDA: ca. 0.6 x LDRXN (the greatest possible relative load reduction must be greater than the value from RLKRLDA otherwise there will be a risk of dead lock!)

TLKRLDAB: ca. 3-5 seconds

TLKRLDAU: ca. 5-7 seconds

TSKRLDAB: 1-2 seconds

TSKRLDAU: 2-4 seconds

CWRLMX: 1 (Addressing of KFLDHBN via ambient temperature in instrument cluster (tumc)).

CWRLMX: 0 (Addressing of KFLDHBN via intake air temperature (tans)).


Abbreviations

Parameter

Description

CWRLMX

Codeword for LDRLMX (boost pressure control)

FKRXTOL

Factor for correction of rlmax at higher engine oil temperature

KFFKRXTM

Factor for correction of rlmax at higher engine temperature

KFFLDEO

Factor for boost pressure intervention at overboost value via knock control

KFFLLDE

Factor for slow boost pressure control intervention at rlmax via knock control

KFFSLDE

Factor for fast boost pressure control intervention (lowering)

KFFWLLDE

Weighting factor for slow boost pressure intervention at rlmax via knock control

KFLDHBN

Boost pressure control upper limit (maximum compressor pressure ratio)

KFTARX

Map for maximum cylinder charge IAT correction factor

KFTARXZK

Map for maximum cylinder charge IAT correction factor during continuous knock

LDORXN

Maximum cylinder charge LDR during E_ldo (overboost error)

LDPBN

Charge pressure control P-limit when engine temperature is too high

LDRXN

Maximum cylinder charge (charge pressure control)

LDRXNZK

Maximum cylinder charge during continuous knock (charge pressure control)

RLKRLDA

RL-threshold for slow charge pressure control intervention (adaption)

SNM08LDUB

Sample point distribution for charge pressure control

SNM08LDUW

Sample point distribution for charge pressure control

SNM12LDUW

Sample point distribution for charge pressure control

STA08LDUB

Sample point distribution for charge pressure control

SWK08LDUW

Sample point distribution for charge pressure control

SWK108LDUW

Sample point distribution for charge pressure control

SWK208LDUW

Sample point distribution for charge pressure control

SY_ATR

System constant: exhaust gas temperature control available

SY_GGGTS

System constant: temperature transducer signal accuracy

SY_TFMO

System constant: TOEL-sensor present (Initial. GGTFM surrogate value)

SY_TFUMG

System constant: ambient temperature sensor present

SY TRLX

System constant: intervention for workshop tester for rlmax present

TLKRLDAB

Time constant for slow LDR-reduction

TLKRLDAU

Time constant for slow LDR-up regulation

TMOTMX

Engine temperature threshold for initial filling of the fuel system

TOELMX

Oil temperature threshold for engine protection during transmission emergency

TOLEWRLMX

Surrogate oil temperature value with faulty CAN-message

TSKRLDAB

Time constant for fast charge pressure control lowering

TSKRLDAU

Time constant for fast charge pressure control up-regulation

Variable

Description

B_ATRF

Condition: exhaust gas temperature control error

B_ATSB

Condition: exhaust gas temperature sensor operational

B_BRLMX

Condition: charge pressure control limit for maximum cylinder charge

B_CKIEN

Condition: CAN-transmission from instrument cluster enable

B_KFZK

Condition: map for knock protection

B_LL

Condition: idle

B_PWF

Condition: power fail

B_TMKIB

Condition: engine temperature from the instrument cluster operational

B_TOLCB

Condition: oil temperature from instrument cluster can be evaluated

B_TUMCB

Condition: error in CAN-ambient temperature information

DFP_ATS

ECU internal error path number: exhaust temperature sensor, cylinder bank 1

DFP_ATS2

ECU internal error path number: exhaust temperature sensor, cylinder bank 2

DFP_LDO

ECU internal error path number: overboost charge pressure control

DFP_TA

ECU internal error path number: intake air temperature TANS (-charge air)

DFP_TM

ECU internal error path number: engine temperature

DFP_TMKI

ECU internal error path number: engine temperature from the instrument cluster

DFP_TOL

ECU internal error path number: oil temperature

DRLMAXO

Delta maximum cylinder charge during overboost

DWKRM_W

Difference: wkrm - wkrmstat

E_ATS

Error flag: exhaust gas temperature sensor, cylinder bank 1

E_ATS2

Error flag: exhaust gas temperatur sensor, cylinder bank 2

E_LDO

Error flag: charge pressure characteristic; upper value exceeded

E_TA

Error flag: intake air temperature

E_TM

Error flag: engine temperature

E_TMKI

Error flag: engine temperature from the instrument cluster

E_TOL

Error flag: oil temperature

FLDRRX_W

Correction factor for maximum cylinder charge from knock control

FLDRXK_W

Factor for LDR rlmax-correction via the short-time part

FLDRXL_W

Factor for LDR rlmax-correction via the long-time part

FLDRXO_W

Factor for charge pressure lowering of the overboost values (drlmaxo)

FRXT

Factor for correction of rlmx as a function of tmki and tol

FRXTA_W

Factor for correction of rlmx as a function of intake air temperature

FUPSRL_W

Factor for system-related conversion of pressure to cylinder charge (16-Bit)

LDRLMS_W

Limiting value for maximum cylinder charge LDR for engine protection

LDRLTS_W

Limting value for maximum cylinder charge LDR for turbocharger protection

NMOT

Engine speed

NMOT W

Engine speed (word)

PIRG_W

Partial pressure of residual gas internal exhaust gas recirculation (16-Bit)

PU

Ambient pressure

RL

Relative cylinder charge

RLMAX_W

Maximum permitted charge at the turbo

RLMXKO_W

Maximum corrected cylinder charge (without limitations)

RLMX_W

Rohwert maximum cylinder charge

TANS

Intake air temperature

TMKI

Engine temperature from the instrument cluster

TMOT

Engine temperature

TMOTLDRLMX

Engine temperature in LDRLMX after selection (tmot/tmkic/tmki)

TOEL

Oil temperature

TOELLDRLMX

Oil temperature in LDRLMX after selection (tolc/toel/TOLEWRLMX)

TOLC

Oil temperature from instrument cluster message

TSEL

Selected temperature (tans/tumc)

TUMC

Ambient temperature from CAN-cluster

VFZG

Vehicle speed

VSRLMX

Additive cylinder charge correction for rlmx from the adjustment system

VSTRLX

Adjustable value of the maximum cylinder charge for the calibrator/tester

WKRMA

Average value of the individual cylinder ignition angle retardation (knock control), general (in emergency mode with safety margin)

WKRMDY_W

Dynamic average value of the individual cylinder ignition angle retardation

WKRMSTAT_W

Quasi-steady state average value of the individual cylinder ignition angle retardation

WKRMSU_W

Total value of the dynamic and static average value of the individual cylinder ignition angle retardation

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