ATR 1.60 (Exhaust Gas Temperature Control)

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See the funktionsrahmen for the following diagrams:

atr-main exhaust gas temperature control overview

atr-atrbb detection of control range

atr-atrb exhaust gas temperature control for cylinder bank 1

atr-atrerb enabling exhaust gas temperature control for cylinder bank 1

atr-atrpi exhaust gas temperature proportional/integral control for cylinder bank 1

atr-atrb2 exhaust gas temperature control for cylinder bank 2

atr-atrerb2 enabling exhaust gas temperature control for cylinder bank 2

atr-atrpi2 exhaust gas temperature proportional/integral control for cylinder bank 2

atr-atrnl limp mode for exhaust gas temperature control

atr-atrko coordination of the control output


ATR 1.60 Function Description

Task:


Protection of components (manifold, turbocharger, etc.) by controlling the exhaust gas temperature. By means of this control, the general enrichment at high load and speed ("full-load enrichment") can be reduced. When general mixture control is insufficient, the exhaust gas temperature control enrichment must also be invoked which leads to reduced fuel consumption.

Principle:

An excessively high exhaust gas temperature can be lowered by enriching the air-fuel mixture. Through this enrichment, more fuel enters the cylinder than is required for stoichiometric combustion of the fuel. The unburned fuel vaporises on the cylinder walls and cools them, whereby the exhaust gas temperature decreases. For this control, the exhaust gas temperature is measured using an exhaust gas temperature sensor or estimated by an exhaust gas temperature model.


As long as the exhaust temperature is below the threshold temperature, there is no control. Thus, there is only a "down regulation" of the exhaust temperature, not an "up regulation". If the desired temperature is reached or exceeded, the control switches. To achieve an enrichment of the mixture, the controller is adjusted to give a desired value of lambda in the "rich" region. This enrichment decreases the exhaust gas temperature, and the controller sets the desired exhaust temperature. When the exhaust temperature drops back below the threshold temperature, the controller takes back the enrichment. If enrichment is no longer required, control is switched off.


Overview of Codeword CATR:

Bit No.

7

6

5

4

3

2

1

0

  • If the value of bit 0 is set equal to 1, this enables exhaust gas temperature control.

ATRBB: Detection Control Range

This function detects the valid control range. Via the configuration byte CATR, the control can, in principle, be switched off. A valid range is usually present when the end of start conditions is detected (B_stend = 1), and the relative load (rl) lies above an applicable threshold rlatr. This control scheme is only available in the near-full load range (rl > rlatr) is active, since exhaust temperatures are only likely to be high in this range. Once the range is exited, control is switched off, e.g. in the transition to idle to shorten the duration of the enrichment.


The valid control range is indicated by the flag B_atrb = 1.


ATRERB: Enabling Exhaust Gas Temperature Control for Bank 1


The exhaust gas temperature control is a flip-flop on or off. The condition flag B_atr = 1 indicates that control is active. If the exhaust gas temperature (tabg) is greater than or equal to the applicable threshold value TABGSS, the control is switched on. The control is switched off when enrichment is no longer required. This is the case when the regulator output dlatr > 0. The controller output dlatr for the exhaust temperature control is then set to zero. It is possible to set a lean limit for the control scheme via the fixed value LATRO. If the current set-lambda without add. If the current desired lambda value without additional lamvoa parts above the limit LATRO (in the lean range) there will be no control. In addition, there is no control if any of the following conditions are met:


(a) No valid control range is detected (B_atrb = 0)

(b) Fuel injector cut-off condition is true (B_bevab = 1)

(c) The exhaust gas temperature sensor indicates an error (E_ats = 1)

(d) The exhaust gas temperature sensor is not ready (B_atsb = 0)

(e) Significant differences between the bank controller control variables were found (E_atrd = 1).


If the engine reaches the rich running limit (B_lagf = 1) while exhaust gas temperature control is active (B_atr = 1), a further enrichment attempt is prohibited by the control scheme (B_atrsp = 1). The current value of the controller output is recorded. However, an enrichment reduction is allowed.


ATRPI2: Exhaust Gas Temperature Proportional/Integral Control for Cylinder Bank 1

The exhaust gas temperature controller is configured as a PI controller, because the "delta lambda controller" intervenes additively. ATRP and ATRI are applied amplification factors for the P and I components. When control is switched off (B_atr = 0) the controller output is set to zero. The integral component in this case is set to equal the negative value of the proportional component (dlatri = -dlatrp), so it follows that the sum is zero. The controller output (dlatr) will be limited to "rich" by the applicable limit DLATRMN. In this case, the integrator is suspended. The exhaust gas temperature tabg falls below the threshold temperature TABGSS or the control is turned off (B_atr = 0), the integrator will be released. When the controller is inhibited (B_atrsp = 1), the last value of controller output (dlatr) is recorded. The integral part is calculated so that the controller output is constant even when a control error remains (dlatri = dlatr - dlatrp).


ATRERB2: Enabling Exhaust Gas Temperature Control for Cylinder Bank 2

As per cylinder bank 1

ATRPI2: Exhaust Gas Temperature Proportional/Integral Control for Cylinder Bank 2

As per cylinder bank 1

ATRNL: Limp Mode for Exhaust Gas Temperature Control

In the event that an exhaust gas temperature sensor fails or is not ready, a limp mode variable (dlatrnl) is provided. The delta lambda target of interest for the limp mode is in the characteristic DLATRNL.


ATRKO: Control Output Coordination

If there is no error in the exhaust gas temperature sensors before, the controller outputs dlatr or dlatr2 through the function outputs dlamatr or dlamatr2 are transferred to lambda coordination. Once a sensor failure (E_ats = 1 or E_ats2 = 1) or the sensors are not operational (B_atsb = 0), or significant bank differences of the controller variables (E_atrd = 1 or E_atrd2 = 1) is detected, the ATR-control range (B_atrb = 1) the limp mode variable dlatrnl are transferred to both banks of lambda coordination.

ATR 1.60 Application Notes

Requirements:


- Application of lambda control

Applications Tools:

VS100

Preassignment of the Parameters:

Erkennung Regelbereich:

- Codeword CATR = 01 (hexadecimal) = 1 (decimal) enable control

- Minimum load for exhaust gas temperature control map KFRLATR (x: engine speed/rpm, y: intake air temperature/°C, z:%)

2000

3000

4000

5000

6000

10

35

60

85

109

Enable exhaust gas temperature control for cylinder bank 1/bank 2: - Threshold exhaust gas temperature for exhaust gas temperature control: TABGSS(2) = 1000°C - Desired AFR upper limit for switching off exhaust gas temperature control: LATRO = 16.0 Exhaust gas temperature control for cylinder bank 1/bank 2: - Threshold exhaust gas temperature for exhaust gas temperature control: TABGSS(2) = 1000°C - Gain factor for proportional component exhaust gas temperature PI control: ATRP = 0.005 l/K - Gain factor for integral component for exhaust gas temperature PI control: ATRI = 0.0005 l/(s ´ K) - Lower limit for exhaust gas temperature control: DLATRMN = -0.3 Exhaust gas temperature control limp mode: - Delta lambda exhaust gas temperature control limp mode:


Engine speed/rpm

2000

3000

4000

5000

6000

DLATRNL

-0.10

-0.13

-0.17

-0.20

-0.23

Procedure: Switching off the Function: To prohibit exhaust gas temperature control set codeword CATR [Bit 0] equal to 0. Affected Functions: %LAMKO through dlamatr_w and dlamatr2_w


Parameter

Description

ATRI

Gain factor (integral component), exhaust gas temperature control

ATRP

Gain factor (proportional component), exhaust gas temperature control

CATR

Configuration byte, exhaust gas temperature control

DLATRMN

Lower limit for exhaust gas temperature control

DLATRNLN

Delta lambda in limp mode, exhaust gas temperature control

KFRLATR

Minimum load for exhaust gas temperature control

LATRO

Desired lambda upper limit, exhaust gas temperature control

SY_STERVK

System constant condition flag for stereo pre-cat

TABGSS

Exhaust gas temperature threshold for exhaust gas temperature control

TABGSS2

Exhaust gas temperature threshold, exhaust gas temperature control, bank 2

Variable

Description

B_ATR

Condition flag for exhaust gas temperature control

B_ATR2

Condition flag for exhaust gas temperature control, cylinder bank 2

B_ATRB

Condition flag for valid operating range, exhaust gas temperature control

B_ATRNL

Condition flag for limp mode in exhaust gas temperature control

B ATRSP

Condition flag for exhaust gas temperature control disabled

B_ATRSP2

Condition flag for exhaust gas temperature control disabled, cylinder bank 2

B_ATSB

Condition flag for exhaust gas temperature sensor ready

B_BEVAB

Condition flag for fuel injector cut-off in cylinder bank 1

B_BEVAB2

Condition flag for fuel injector cut-off in cylinder bank 2

B_LALGF

Condition flag for "lambda rich" limit active

B_LALGF2

Condition flag for "lambda rich" limit active

B STEND

Condition flag for end of start conditions reached

DLAMATR2_W

Delta lambda for exhaust gas temperature control, cylinder bank 2

DLAMATR_W

Delta lambda for exhaust gas temperature control

DLATR2_W

Delta lambda for exhaust gas temperature control, cylinder bank 2

DLATRI2_W

Integral component, exhaust gas temperature PI control, cylinder bank 2

DLATRI_W

Integral component, exhaust gas temperature PI control

DLATRNL_W

Delta lambda in limp mode, exhaust gas temperature control

DLATRP2_W

Proportional component, exhaust gas temperature PI control, cylinder bank 2

DLATRP W

Proportional component, exhaust gas temperature PI control

DLATR_W

Delta lambda, exhaust gas temperature control

E_ATRD

Error flag: cylinder bank difference, exhaust gas temperature control

E_ATRD2

Error flag: cylinder bank difference, exhaust gas temperature control bank 2

E_ATS

Error flag: exhaust gas temperature sensor

E_ATS2

Error flag: exhaust gas temperature sensor, cylinder bank 2

LAMVOA2_W

Lambda pilot control without additive parts, cylinder bank 2

LAMVOA_W

Lambda pilot control without additive parts

NMOT

Engine speed

RL

Relative cylinder charge

RLATR

Load threshold for exhaust gas temperature control

TABG2_W

Exhaust gas temperature, cylinder bank 2

TABG_W

Exhaust gas temperature

TANS

Intake air temperature

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