View source for ATR 1.60 (Exhaust Gas Temperature Control)

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

<u>ATR 1.60 Function Description</u>

<u>Task:</u>

 
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
(&quot;full-load enrichment&quot;) 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.

<u>Principle:</u>

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 &quot;down regulation&quot; of the exhaust
temperature, not an &quot;up regulation&quot;. 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
&quot;rich&quot; 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.

  
<u>Overview of Codeword CATR:</u>
                         
{| border="1"
|-
| 
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.

u>ATRBB: Detection Control Range</u>

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 &gt; 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.

  
<u>ATRERB:
Enabling Exhaust Gas Temperature Control for Bank 1</u>

  
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 &gt; 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.

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

  
The exhaust gas temperature controller is configured as a PI controller, because
the &quot;delta lambda controller&quot; 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
&quot;rich&quot; 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).

  
<u>ATRERB2:
Enabling Exhaust Gas Temperature Control for Cylinder Bank 2</u>

  
As
per cylinder bank 1

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

As per cylinder bank 1

<u>ATRNL: Limp Mode for Exhaust Gas Temperature Control</u>

  
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.

  
<u>ATRKO: Control Output
Coordination</u>

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.

  
<u>ATR 1.60 Application Notes</u>

  
<u>Requirements:</u>

 
-
Application of lambda control

  
<u>Applications Tools:</u>

 
VS100

  
<u>Preassignment of the Parameters:</u>

 
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:%)

                                                    
{| border="1"
|-
|  
| 
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:

                   
{| border="1"
|-
| 
Engine
speed/rpm
| 
2000
| 
3000
| 
4000
| 
5000
| 
6000
|-
| 
DLATRNL
| 
-0.10
| 
-0.13
| 
-0.17
| 
-0.20
| 
-0.23
|}  
<u>Procedure:</u>
<u>Switching off the Function:</u>
To
prohibit exhaust gas temperature control set codeword CATR [Bit 0] equal to 0.
<u>Affected
Functions:</u>
%LAMKO
through dlamatr_w and dlamatr2_w

                                                                                                                                                                                        
{| border="1"
|-
| 
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 &quot;lambda rich&quot; limit active
|-
| 
B_LALGF2
| 
Condition flag for &quot;lambda rich&quot; 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
|}