Difference between revisions of "RKTI 11.40 (Calculation of Injection Time ti from Relative Fuel Mass rk)"

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Line 2: Line 2:
  
 
    
 
    
ti_w represents a physical value of injection time which is
+
ti_w represents a physical value of injection time which is correct also during start conditions. During start the physical value of ti_b1, ti_b2 and ti_tvu_w has to be corrected by the user by a factor of 8, because start quantisation of ti_b1 is internally corrected by dividing by 8 to store large ti-values into a ‘word’ variable instead of a ‘long’ variable.
correct also during start conditions. During start the physical value of ti_b1,
+
ti_b2 and ti_tvu_w has to be corrected by the user by a factor of 8, because
+
start quantisation of ti_b1 is internally corrected by dividing by 8 to store
+
large ti-values into a ‘word’ variable instead of a ‘long’ variable.
+
  
 
    
 
    
Line 24: Line 20:
  
 
    
 
    
This function calculates the effective injection time before
+
This function calculates the effective injection time before fine tuning (tevfa_w, tevfa2_w) from the relative fuel mass (rk_w, rk2_w) and the factor frkte. With an ideal fuel supply system, tevfa_w + tvu_w, tevfa2_w + tvu_w should result in lambda of 1.0 in the combustion chamber, with pilot control to lambda = 1.0 and neutral values ​​of all mixture adaptations.
fine tuning (tevfa_w, tevfa2_w) from the relative fuel mass (rk_w, rk2_w) and
+
the factor frkte. With an ideal fuel supply system, tevfa_w + tvu_w, tevfa2_w +
+
tvu_w should result in lambda of 1.0 in the combustion chamber, with pilot
+
control to lambda = 1.0 and neutral values ​​of all mixture
+
adaptations.
+
  
 
    
 
    
In practice, a deviation in lambda may occur due to injector
+
In practice, a deviation in lambda may occur due to injector nonlinearities or pulses in the fuel system. This deviation is corrected using the map FKKVS as a function of engine speed (nmot_w) and effective injection time (tevfa_w or tevfa2_w). The corrected effective injection time is te_w or te2_w.
nonlinearities or pulses in the fuel system. This deviation is corrected using
+
By adding the battery voltage correction for the injectors, the actuation time is calculated thus: ti_b1 = te_w + tvu_w. The function ACIFI controls the actuation times ti_b1 and ti_b2 for the associated injectors. In a single bank system (SY_stervk = false) the actuation times for bank 1 (ti_b1 or ti_b2) are forwarded to CIFI. In order to achieve the long injection times required during
the map FKKVS as a function of engine speed (nmot_w) and effective injection
+
starting conditions, the quantization times ti_b1, ti_b2 are increased by a factor of 8 which thus expands the range to 1677.696 ms. The same applies for the additive quantity ti_tvu_w.
time (tevfa_w or tevfa2_w). The corrected effective injection time is te_w or te2_w.
+
By adding the battery voltage correction for the injectors, the actuation time is
+
calculated thus: ti_b1 = te_w + tvu_w. The function ACIFI controls the actuation
+
times ti_b1 and ti_b2 for the associated injectors. In a single bank system
+
(SY_stervk = false) the actuation times for bank 1 (ti_b1 or ti_b2) are
+
forwarded to CIFI. In order to achieve the long injection times required during
+
starting conditions, the quantization times ti_b1, ti_b2 are increased by a
+
factor of 8 which thus expands the range to 1677.696 ms. The same applies for
+
the additive quantity ti_tvu_w.
+
  
 
    
 
    
Therefore, a 16 bit value is required for the interface to the
+
Therefore, a 16 bit value is required for the interface to the function ACIFI. This is important for runtime reasons for normal operation. During start conditions, VS100 measurements of the physically indicated injection time are multiplied by a factor of 8. The resolution during start conditions for ti_b1, ti_b2 and ti_tvu_w is 25.6 microseconds, whereas in normal operation it is 3.2 microseconds.
function ACIFI. This is important for runtime reasons for normal operation. During
+
start conditions, VS100 measurements of the physically indicated injection time
+
are multiplied by a factor of 8. The resolution during start conditions for ti_b1,
+
ti_b2 and ti_tvu_w is 25.6 microseconds, whereas in normal operation it is 3.2
+
microseconds.
+
  
 
    
 
    
The RAM cells ti_w and ti_2_w show the physically correct injection
+
The RAM cells ti_w and ti_2_w show the physically correct injection time during both start conditions and also normal operation with a resolution of 16 microseconds. The resolutions are valid for a 20 MHz processor.
time during both start conditions and also normal operation with a resolution
+
of 16 microseconds. The resolutions are valid for a 20 MHz processor.
+
  
 
    
 
    
The minimum injection time TEMIN or TEMINVA is set when
+
The minimum injection time TEMIN or TEMINVA is set when outputs B_va = true, B_temin = true or B_temin2 = true. This serves to lock out the lambda control. The threshold value TEMINVA is differentiated from TEMIN with a cold engine when the wall film degradation is not properly emulated by the thinning-delay because te_w limits TEMIN. At higher speeds it is possible that the available theoretical maximum injection time is not sufficient to obtain the required target torque. Therefore, an injection time timx_w that is larger than the maximum possible injection time timxth_w is deployed until the desired torque is withdrawn and timx_w is not larger than timxth_w. For this purpose, the
outputs B_va = true, B_temin = true or B_temin2 = true. This serves to lock out
+
control error dtimx_w is assigned to a PI controller. When the controller is active, the output controlled variable mitibgr_w represents the desired torque.
the lambda control. The threshold value TEMINVA is differentiated from TEMIN
+
When the controller is inactive, mitibgr_w receives the value 100%. The desired torque in %MDBGRG is obtained by initializing with mifab_w and mitibgr_w. In order to avoid jumps in the nominal torque, the integrator of the integral component is initialized with mifab_w.
with a cold engine when the wall film degradation is not properly emulated by
+
the thinning-delay because te_w limits TEMIN. At higher speeds it is possible
+
that the available theoretical maximum injection time is not sufficient to
+
obtain the required target torque. Therefore, an injection time timx_w that is
+
larger than the maximum possible injection time timxth_w is deployed until the desired
+
torque is withdrawn and timx_w is not larger than timxth_w. For this purpose, the
+
control error dtimx_w is assigned to a PI controller. When the controller is
+
active, the output controlled variable mitibgr_w represents the desired torque.
+
When the controller is inactive, mitibgr_w receives the value 100%. The desired
+
torque in %MDBGRG is obtained by initializing with mifab_w and mitibgr_w. In
+
order to avoid jumps in the nominal torque, the integrator of the integral
+
component is initialized with mifab_w.
+
  
 
    
 
    
The controller is activated as soon as timx_w exceeds the
+
The controller is activated as soon as timx_w exceeds the speed-dependent threshold timxth_w. The controller remains in operation until timx_w < timxth_w AND mitibgr_w > mifab_w. See Applications Information.
speed-dependent threshold timxth_w. The controller remains in operation until
+
timx_w < timxth_w AND mitibgr_w > mifab_w. See Applications
+
Information.
+
  
 
    
 
    
Line 98: Line 58:
 
    
 
    
 
''rho''<sub>air</sub> = air density (1.293 g/dm<sup>3</sup> at 0°C and 1013 mbar)
 
''rho''<sub>air</sub> = air density (1.293 g/dm<sup>3</sup> at 0°C and 1013 mbar)
 
 
   
 
   
 
V<sub>hcyl</sub> = Volume of a cylinder hub in dm<sup>3</sup>
 
V<sub>hcyl</sub> = Volume of a cylinder hub in dm<sup>3</sup>
 
 
   
 
   
 
Q<sub>stat</sub> = injector constant with ''n''-heptane
 
Q<sub>stat</sub> = injector constant with ''n''-heptane
 
 
   
 
   
 
1.05 = injector correction factor for petrol
 
1.05 = injector correction factor for petrol
 
 
   
 
   
14.7 = Stoichiometric air quantity at lambda =
+
14.7 = Stoichiometric air quantity at lambda = 1.0
1.0
+
 
+
 
   
 
   
1.67x10<sup>–5</sup> =
+
1.67x10<sup>–5</sup> = conversion factor minutes to milliseconds.
conversion factor minutes to milliseconds.
+
  
 
    
 
    
Calculation of the correction for fuel supply systems where
+
Calculation of the correction for fuel supply systems where the reference pressure of the fuel pressure regulator is ambient pressure:
the reference pressure of the fuel pressure regulator is ambient pressure:
+
  
 
    
 
    
FRLFSDP = SQRT[pdr_evmes/(pdr_akt
+
FRLFSDP = SQRT[pdr_evmes/(pdr_akt + (pu - ps))]
+ (pu - ps))]
+
  
 
    
 
    
Line 128: Line 79:
  
 
    
 
    
pdr_evmes = absolute pressure in the fuel system before the
+
pdr_evmes = absolute pressure in the fuel system before the injectors at the injector constant (Qstat) generally 3 bar
injectors at the injector constant (Qstat) generally 3 bar
+
 
+
 
   
 
   
 
pdr_akt = actual fuel system pressure
 
pdr_akt = actual fuel system pressure
 
 
   
 
   
 
pu = ambient pressure
 
pu = ambient pressure
 
 
   
 
   
 
ps = intake manifold pressure
 
ps = intake manifold pressure
  
 
    
 
    
For systems that take their reference pressure from the
+
For systems that take their reference pressure from the intake manifold pu - ps = 0 is used in the calculation above.
intake manifold pu - ps = 0 is used in the calculation
+
above.
+
  
 
    
 
    
Line 149: Line 94:
  
 
    
 
    
For a fuel pressure of 3 bar, the results for FRLFSDP (where
+
For a fuel pressure of 3 bar, the results for FRLFSDP (where dpus = pu - ps) are as follows:
dpus = pu - ps) are as follows:
+
  
 
                                                                                  
 
                                                                                  
Line 157: Line 101:
 
|  
 
|  
 
Naturally-aspirated Engine
 
Naturally-aspirated Engine
 
 
 
|  
 
|  
 
Turbocharged Engine
 
Turbocharged Engine
 
 
 
|-
 
|-
 
|  
 
|  
 
dpus/mbar
 
dpus/mbar
 
 
 
|  
 
|  
 
FRLFSDP
 
FRLFSDP
 
 
 
|  
 
|  
 
dpus/mbar
 
dpus/mbar
 
 
 
|  
 
|  
 
FRLFSDP
 
FRLFSDP
 
 
 
|-
 
|-
 
|  
 
|  
 
0
 
0
 
 
 
|  
 
|  
 
1.0000
 
1.0000
 
 
 
|  
 
|  
 
-1200*
 
-1200*
 
 
 
|  
 
|  
 
1.2990
 
1.2990
 
 
 
|-
 
|-
 
|  
 
|  
 
100
 
100
 
 
 
|  
 
|  
 
0.9837
 
0.9837
 
 
 
|  
 
|  
 
-1000
 
-1000
 
 
 
|  
 
|  
 
1.2247
 
1.2247
 
 
 
|-
 
|-
 
|  
 
|  
 
200
 
200
 
 
 
|  
 
|  
 
0.9682
 
0.9682
 
 
 
|  
 
|  
 
-800
 
-800
 
 
 
|  
 
|  
 
1.1678
 
1.1678
 
 
 
|-
 
|-
 
|  
 
|  
 
300
 
300
 
 
 
|  
 
|  
 
0.9535
 
0.9535
 
 
 
|  
 
|  
 
-600
 
-600
 
 
 
|  
 
|  
 
1.1180
 
1.1180
 
 
 
|-
 
|-
 
|  
 
|  
 
400
 
400
 
 
 
|  
 
|  
 
0.9393
 
0.9393
 
 
 
|  
 
|  
 
-400
 
-400
 
 
 
|  
 
|  
 
1.0742
 
1.0742
 
 
 
|-
 
|-
 
|  
 
|  
 
500
 
500
 
 
 
|  
 
|  
 
0.9258
 
0.9258
 
 
 
|  
 
|  
 
-200
 
-200
 
 
 
|  
 
|  
 
1.0351
 
1.0351
 
 
 
|-
 
|-
 
|  
 
|  
 
600
 
600
 
 
 
|  
 
|  
 
0.9129
 
0.9129
 
 
 
|  
 
|  
 
0
 
0
 
 
 
|  
 
|  
 
1.0000
 
1.0000
 
 
 
|-
 
|-
 
|  
 
|  
 
700
 
700
 
 
 
|  
 
|  
 
0.9005
 
0.9005
 
 
 
|  
 
|  
 
200
 
200
 
 
 
|  
 
|  
 
0.9682
 
0.9682
 
 
 
|-
 
|-
 
|  
 
|  
 
800
 
800
 
 
 
|  
 
|  
 
0.8885
 
0.8885
 
 
 
|  
 
|  
 
400
 
400
 
 
 
|  
 
|  
 
0.9393
 
0.9393
 
 
 
|-
 
|-
 
|   
 
|   
Line 338: Line 198:
 
|  
 
|  
 
600
 
600
 
 
 
|  
 
|  
 
0.9129
 
0.9129
 
 
 
|-
 
|-
 
|   
 
|   
Line 349: Line 205:
 
|  
 
|  
 
800
 
800
 
 
 
|  
 
|  
 
0.8885
 
0.8885
 
 
 
|}   
 
|}   
 
*Boost pressure = 1800 mbar, ambient pressure = 600 mbar
 
*Boost pressure = 1800 mbar, ambient pressure = 600 mbar
  
 
    
 
    
For consistency reasons, 11 sampling points for vacuum and
+
For consistency reasons, 11 sampling points for vacuum and turbo are used with the turbo-values.
turbo are used with the turbo-values.
+
  
 
    
 
    
In the charge sampling and injection application in
+
In the charge sampling and injection application in returnless fuel systems via the code word for the reference pressure for the fuel pressure regulator (CWPKAPP), the constant PSAPES (intake manifold pressure for injection application) is used as a substitute value where the modelled intake
returnless fuel systems via the code word for the reference pressure for the fuel
+
manifold pressure ps_w has not been applied. Thus the manifold pressure can be set directly with a VS100 processor. With the VS20 processor, the pressure PSAPES can be changed with an adjustment factor between 0 and 2 via the RAM cell vsfpses (pses_w = PSAPES x vsfpses).
pressure regulator (CWPKAPP), the constant PSAPES (intake manifold pressure for
+
injection application) is used as a substitute value where the modelled intake
+
manifold pressure ps_w has not been applied. Thus the manifold pressure can be
+
set directly with a VS100 processor. With the VS20 processor, the pressure PSAPES
+
can be changed with an adjustment factor between 0 and 2 via the RAM cell
+
vsfpses (pses_w = PSAPES ´ vsfpses).
+
  
 
    
 
    
The initial value for PSAPES is 1013 mbar. If this value (in
+
The initial value for PSAPES is 1013 mbar. If this value (in conjunction with a factor of 2 from vsfpses) does not define the maximum manifold pressure for turbocharged engines with VS20, the one-off value of PSAPES must be increased with VS100.
conjunction with a factor of 2 from vsfpses) does not define the maximum
+
manifold pressure for turbocharged engines with VS20, the one-off value of
+
PSAPES must be increased with VS100.
+
  
 
    
 
    
Line 382: Line 224:
  
 
   
 
   
Map size in program development nmot ´ tevfa_w = 10 ´ 10
+
Map size in program development nmot x tevfa_w = 10 x 10
  
 
    
 
    
Line 392: Line 234:
 
|  
 
|  
 
Speed
 
Speed
 
 
 
|  
 
|  
 
800
 
800
 
 
 
|  
 
|  
 
1400
 
1400
 
 
 
|  
 
|  
 
2000
 
2000
 
 
 
|  
 
|  
 
2600
 
2600
 
 
 
|  
 
|  
 
3200
 
3200
 
 
 
|  
 
|  
 
3800
 
3800
 
 
 
|  
 
|  
 
4400
 
4400
 
 
 
|  
 
|  
 
5000
 
5000
 
+
|
+
|  
+
 
5600
 
5600
 
 
 
|  
 
|  
 
6200
 
6200
 
 
 
|  
 
|  
 
RPM
 
RPM
 
 
 
|-
 
|-
 
|  
 
|  
 
Tevfa_w
 
Tevfa_w
 
 
 
|  
 
|  
 
1.5
 
1.5
 
 
 
|  
 
|  
 
2.5
 
2.5
 
 
 
|  
 
|  
 
3.5
 
3.5
 
 
 
|  
 
|  
 
4.5
 
4.5
 
 
 
|  
 
|  
 
5.5
 
5.5
 
 
 
|  
 
|  
 
6.5
 
6.5
 
 
 
|  
 
|  
 
7.5
 
7.5
 
 
 
|  
 
|  
 
8.5
 
8.5
 
 
 
|  
 
|  
 
9.5
 
9.5
 
 
 
|  
 
|  
 
10.5
 
10.5
 
 
 
|  
 
|  
 
ms
 
ms
 
 
 
|-
 
|-
 
|  
 
|  
 
Value
 
Value
 
 
 
|  
 
|  
 
1.0
 
1.0
 
 
 
|  
 
|  
 
1.0
 
1.0
 
 
 
|  
 
|  
 
1.0
 
1.0
 
 
 
|  
 
|  
 
1.0
 
1.0
 
 
 
|  
 
|  
 
1.0
 
1.0
 
 
 
|  
 
|  
 
1.0
 
1.0
 
 
 
|  
 
|  
 
1.0
 
1.0
 
 
 
|  
 
|  
 
1.0
 
1.0
 
+
|
+
|  
+
 
1.0
 
1.0
 
 
 
|  
 
|  
 
1.0
 
1.0
 
 
 
|   
 
|   
 
|}   
 
|}   
The characteristic field FKKVS corrects errors in the fuel
+
The characteristic field FKKVS corrects errors in the fuel system (pulses in returnless fuel systems)
system (pulses in returnless fuel systems)
+
  
 
   
 
   
The map size of FKKVS can be extended to about nmot ´ tevfa_w = 10 ´ 10 auf
+
The map size of FKKVS can be extended to about nmot x tevfa_w = 10 x 10 to 16 x 10.
16 ´ 10.
+
  
 
   
 
   
This is especially important to simplify the application for
+
This is especially important to simplify the application for proportional systems. The speed &#8203;&#8203;sample points &#8203;&#8203;should match the number and values of the map KFPRG in the
proportional systems. The speed &#8203;&#8203;sample points
+
&#8203;&#8203;should match the number and values of the map KFPRG in the
+
 
function BGSRM.
 
function BGSRM.
  
Line 551: Line 319:
  
 
   
 
   
TEMINVA: 1 milliseconds so that overall, the same TEMIN is
+
TEMINVA: 1 milliseconds so that overall, the same TEMIN is active
active
+
  
 
   
 
   
TEMINVA: 0 milliseconds so that it is inactive when the
+
TEMINVA: 0 milliseconds so that it is inactive when the engine is cold and thinning delay B_va = true, te to TEMIN seated and so that the wall film is not broken down properly.
engine is cold and thinning delay B_va = true, te to TEMIN seated and so that
+
the wall film is not broken down properly.
+
  
 
   
 
   
ti-resolution values &#8203;&#8203;are valid for a 20 MHz
+
ti-resolution values &#8203;&#8203;are valid for a 20 MHz processor frequency. Otherwise thery must be converted thus: 20 MHz / (current processor frequency [MHz]).
processor frequency. Otherwise thery must be converted thus: 20 MHz / (current
+
processor frequency [MHz]).
+
  
 
    
 
    
Line 568: Line 331:
  
 
   
 
   
ti_b1, ti_b2 25.6 microseconds. Measurements from VS100 must
+
ti_b1, ti_b2 25.6 microseconds. Measurements from VS100 must be multiplied by a factor of 8.
be multiplied by a factor of 8.
+
 
+
 
   
 
   
ti_tvu_w 25.6 microseconds. Measurements from VS100 must be
+
ti_tvu_w 25.6 microseconds. Measurements from VS100 must be multiplied by a factor of 8.
multiplied by a factor of 8.
+
 
+
 
   
 
   
 
ti_w, ti2_w 16 microseconds.
 
ti_w, ti2_w 16 microseconds.
 
 
   
 
   
 
te_w, te2_w not available.
 
te_w, te2_w not available.
Line 586: Line 344:
 
   
 
   
 
ti_b1, ti_b2 3.2 microseconds.
 
ti_b1, ti_b2 3.2 microseconds.
 
 
   
 
   
 
ti_tvu_w 3.2 microseconds.
 
ti_tvu_w 3.2 microseconds.
 
 
   
 
   
 
ti_w, ti2_w 16 microseconds.
 
ti_w, ti2_w 16 microseconds.
 
 
   
 
   
 
te_w, te2_w 3.2 microseconds.
 
te_w, te2_w 3.2 microseconds.
 
 
    
 
    
 
<u>First inputs:</u>
 
<u>First inputs:</u>
Line 601: Line 355:
 
   
 
   
 
ZTSPEV = 240 seconds
 
ZTSPEV = 240 seconds
 
 
    
 
    
 
TVTSPEV
 
TVTSPEV
 
 
                  
 
                  
 
{| border="1"
 
{| border="1"
Line 610: Line 362:
 
|  
 
|  
 
Etvmodev [°]
 
Etvmodev [°]
 
 
 
|  
 
|  
 
-20
 
-20
 
 
 
|  
 
|  
 
0
 
0
 
 
 
|  
 
|  
 
100
 
100
 
 
 
|  
 
|  
 
120
 
120
 
 
 
|-
 
|-
 
|  
 
|  
 
tvsp_w [ms]
 
tvsp_w [ms]
 
 
 
|  
 
|  
 
0
 
0
 
 
 
|  
 
|  
 
0
 
0
 
 
 
|  
 
|  
 
0
 
0
 
 
 
|  
 
|  
 
0
 
0
 
 
 
|}   
 
|}   
 
<u>DMIL</u>
 
<u>DMIL</u>
Line 657: Line 389:
 
   
 
   
 
Bit 0 true: controller activated
 
Bit 0 true: controller activated
 
 
   
 
   
 
Bit 0 false: controller deactivated
 
Bit 0 false: controller deactivated
 
 
   
 
   
 
Bit 1 true: inputs B_ba and B_bag both active
 
Bit 1 true: inputs B_ba and B_bag both active
 
 
   
 
   
 
KMITIBGR = 15 %/ms*s
 
KMITIBGR = 15 %/ms*s
 
 
   
 
   
 
PVMITIBGR = 0.8 %/ms
 
PVMITIBGR = 0.8 %/ms
  
 
+
     
'''Explanation of
+
Variables'''
+
 
+
                                                                                                                                                                                                                                 
+
 
{| border="1"
 
{| border="1"
 
|-
 
|-
 
|  
 
|  
 
'''Variable'''
 
'''Variable'''
 
 
 
|  
 
|  
 
'''Description'''
 
'''Description'''
 
 
 
|-
 
|-
 
|  
 
|  
 
CWDMIL
 
CWDMIL
 
 
 
|  
 
|  
 
Code word ti-continuous wave control RKTI
 
Code word ti-continuous wave control RKTI
 
 
 
|-
 
|-
 
|  
 
|  
 
CWPKAPP
 
CWPKAPP
 
 
 
|  
 
|  
 
Application code word for the fuel pressure
 
Application code word for the fuel pressure
 
regulator pressure reference
 
regulator pressure reference
 
 
 
|-
 
|-
 
|  
 
|  
 
FKKVS
 
FKKVS
 
 
 
|  
 
|  
 
Correction factor for the fuel supply system
 
Correction factor for the fuel supply system
 
 
 
|-
 
|-
 
|  
 
|  
 
FRLFSDP
 
FRLFSDP
 
 
 
|  
 
|  
 
Injection correction RLFS
 
Injection correction RLFS
 
 
 
|-
 
|-
 
|  
 
|  
 
KMITIBGR
 
KMITIBGR
 
 
 
|  
 
|  
 
On-slope factor for the integration of dtimx_w
 
On-slope factor for the integration of dtimx_w
 
through torque limitation
 
through torque limitation
 
 
 
|-
 
|-
 
|  
 
|  
 
KRKTE
 
KRKTE
 
 
 
|  
 
|  
 
Conversion of relative fuel mass rk to
 
Conversion of relative fuel mass rk to
 
effective injection time te
 
effective injection time te
 
 
 
|-
 
|-
 
|  
 
|  
 
PSAPES
 
PSAPES
 
 
 
|  
 
|  
 
Intake manifold injection for application
 
Intake manifold injection for application
 
 
 
|-
 
|-
 
|  
 
|  
 
PVMITIBGR
 
PVMITIBGR
 
 
 
|  
 
|  
 
Proportional gain factor for torque limitation
 
Proportional gain factor for torque limitation
 
through continuous wave injection
 
through continuous wave injection
 
 
 
|-
 
|-
 
|  
 
|  
 
SY_STERVK
 
SY_STERVK
 
 
 
|  
 
|  
 
System constant condition: stereo before
 
System constant condition: stereo before
 
catalytic converter
 
catalytic converter
 
 
 
|-
 
|-
 
|  
 
|  
 
TEMIN
 
TEMIN
 
 
 
|  
 
|  
 
minimum TE
 
minimum TE
 
 
 
|-
 
|-
 
|  
 
|  
 
TEMINVA
 
TEMINVA
 
 
 
|  
 
|  
 
minimum TE at VA
 
minimum TE at VA
 
 
 
|-
 
|-
 
|  
 
|  
 
TVTSPEV
 
TVTSPEV
 
 
 
|  
 
|  
 
Correction of the injection time depending on
 
Correction of the injection time depending on
 
evtmod
 
evtmod
 
 
 
|-
 
|-
 
|  
 
|  
 
TVUB
 
TVUB
 
 
 
|  
 
|  
 
Voltage correction
 
Voltage correction
 
 
 
|-
 
|-
 
|  
 
|  
 
ZTSPEV
 
ZTSPEV
 
 
 
|  
 
|  
 
Time constant for filtering evtmod taking tvu-control
 
Time constant for filtering evtmod taking tvu-control
 
into account
 
into account
 
 
 
|-
 
|-
 
|   
 
|   
Line 824: Line 488:
 
|  
 
|  
 
B_BA
 
B_BA
 
 
 
|  
 
|  
 
Acceleration enrichment condition (indicator)
 
Acceleration enrichment condition (indicator)
 
 
 
|-
 
|-
 
|  
 
|  
 
B_BAG
 
B_BAG
 
 
 
|  
 
|  
 
Strong acceleration enrichment condition
 
Strong acceleration enrichment condition
 
 
 
|-
 
|-
 
|  
 
|  
 
B_ENIMITI
 
B_ENIMITI
 
 
 
|  
 
|  
 
Integrator release condition for
 
Integrator release condition for
 
torque limitation through continuous wave injection
 
torque limitation through continuous wave injection
 
 
 
|-
 
|-
 
|  
 
|  
 
B_STEND
 
B_STEND
 
 
 
|  
 
|  
 
End of start condition
 
End of start condition
 
 
 
|-
 
|-
 
|  
 
|  
 
B_TEMIN
 
B_TEMIN
 
 
 
|  
 
|  
 
TEMIN-limiting condition active, Bank 1
 
TEMIN-limiting condition active, Bank 1
 
 
 
|-
 
|-
 
|  
 
|  
 
B_TEMIN2
 
B_TEMIN2
 
 
 
|  
 
|  
 
TEMIN-limiting condition active, Bank 2
 
TEMIN-limiting condition active, Bank 2
 
 
 
|-
 
|-
 
|  
 
|  
 
B_VA
 
B_VA
 
 
 
|  
 
|  
 
Wall-film thinning delay condition (indicator)
 
Wall-film thinning delay condition (indicator)
 
 
 
|-
 
|-
 
|  
 
|  
 
DPUS_W
 
DPUS_W
 
 
 
|  
 
|  
 
Delta intake manifold pressure environment
 
Delta intake manifold pressure environment
 
 
 
|-
 
|-
 
|  
 
|  
 
DTIMX_W
 
DTIMX_W
 
 
 
|  
 
|  
 
Difference between theoretical and maximum injection
 
Difference between theoretical and maximum injection
 
time
 
time
 
 
 
|-
 
|-
 
|  
 
|  
 
EVTMOD
 
EVTMOD
 
 
 
|  
 
|  
 
Intake valve temperature models (temperature
 
Intake valve temperature models (temperature
 
model)
 
model)
 
 
 
|-
 
|-
 
|  
 
|  
 
EVTMODEV
 
EVTMODEV
 
 
 
|  
 
|  
 
Filtered value of evtmod taking into account
 
Filtered value of evtmod taking into account
 
the formation of tvu_w
 
the formation of tvu_w
 
 
 
|-
 
|-
 
|  
 
|  
 
FRKTE_W
 
FRKTE_W
 
 
 
|  
 
|  
 
Conversion factor relative fuel mass rk to
 
Conversion factor relative fuel mass rk to
 
effective injection time te
 
effective injection time te
 
 
 
|-
 
|-
 
|  
 
|  
 
FTEK2_W
 
FTEK2_W
 
 
 
|  
 
|  
 
Correction factor for effective injection time,
 
Correction factor for effective injection time,
 
Bank 2
 
Bank 2
 
 
 
|-
 
|-
 
|  
 
|  
 
FTEK_W
 
FTEK_W
 
 
 
|  
 
|  
 
Correction factor for effective injection time
 
Correction factor for effective injection time
 
 
 
|-
 
|-
 
|  
 
|  
 
MIFAB_W
 
MIFAB_W
 
 
 
|  
 
|  
 
Limited indexed driver-desired torque
 
Limited indexed driver-desired torque
 
 
 
|-
 
|-
 
|  
 
|  
 
MITIBGRI_W
 
MITIBGRI_W
 
 
 
|  
 
|  
 
I-component for torque limitation via
 
I-component for torque limitation via
 
ti-control during continuous injection
 
ti-control during continuous injection
 
 
 
|-
 
|-
 
|  
 
|  
 
MITIBGRP_W
 
MITIBGRP_W
 
 
 
|  
 
|  
 
P-component for torque limitation
 
P-component for torque limitation
 
via ti-control during continuous injection
 
via ti-control during continuous injection
 
 
 
|-
 
|-
 
|  
 
|  
 
MITIBGR_W
 
MITIBGR_W
 
 
 
|  
 
|  
 
Torque limitation via ti-control during
 
Torque limitation via ti-control during
 
continuous injection
 
continuous injection
 
 
 
|-
 
|-
 
|  
 
|  
 
NMOT
 
NMOT
 
 
 
|  
 
|  
 
Engine speed
 
Engine speed
 
 
 
|-
 
|-
 
|  
 
|  
 
NMOT_W
 
NMOT_W
 
 
 
|  
 
|  
 
Engine speed
 
Engine speed
 
 
 
|-
 
|-
 
|  
 
|  
 
PS_W
 
PS_W
 
 
 
|  
 
|  
 
Manifold Absolute Pressure (Word)
 
Manifold Absolute Pressure (Word)
 
 
 
|-
 
|-
 
|  
 
|  
 
PU_W
 
PU_W
 
 
 
|  
 
|  
 
Ambient pressure
 
Ambient pressure
 
 
 
|-
 
|-
 
|  
 
|  
 
RK2_W
 
RK2_W
 
 
 
|  
 
|  
 
Relative fuel mass, Bank2
 
Relative fuel mass, Bank2
 
 
 
|-
 
|-
 
|  
 
|  
 
RK_W
 
RK_W
 
 
 
|  
 
|  
 
Relative fuel mass
 
Relative fuel mass
 
 
 
|-
 
|-
 
|  
 
|  
 
TE2_W
 
TE2_W
 
 
 
|  
 
|  
 
Effective injection time Bank2 (word)
 
Effective injection time Bank2 (word)
 
 
 
|-
 
|-
 
|  
 
|  
 
TEVFA2_W
 
TEVFA2_W
 
 
 
|  
 
|  
 
Effective injection time before trim (word)
 
Effective injection time before trim (word)
 
 
 
|-
 
|-
 
|  
 
|  
 
TEVFAKGE_W
 
TEVFAKGE_W
 
 
 
|  
 
|  
 
Addressing map FKKVS with effective injection
 
Addressing map FKKVS with effective injection
 
time before fine-tuning
 
time before fine-tuning
 
 
 
|-
 
|-
 
|  
 
|  
 
TEVFA_W
 
TEVFA_W
 
 
 
|  
 
|  
 
Effective injection time before trim (word)
 
Effective injection time before trim (word)
 
 
 
|-
 
|-
 
|  
 
|  
 
TE W
 
TE W
 
 
 
|  
 
|  
 
Effective injection time (word)
 
Effective injection time (word)
 
 
 
|-
 
|-
 
|  
 
|  
 
TI2_W
 
TI2_W
 
 
 
|  
 
|  
 
Injection time for cylinder 2 (word)
 
Injection time for cylinder 2 (word)
 
 
 
|-
 
|-
 
|  
 
|  
 
TIMXTH_W
 
TIMXTH_W
 
 
 
|  
 
|  
 
Theoretical maximum injection time
 
Theoretical maximum injection time
 
 
 
|-
 
|-
 
|  
 
|  
 
TIMX_W
 
TIMX_W
 
 
 
|  
 
|  
 
Maximum injection time
 
Maximum injection time
 
 
 
|-
 
|-
 
|  
 
|  
 
TI B1
 
TI B1
 
 
 
|  
 
|  
 
Injection time for injectors in Bank1
 
Injection time for injectors in Bank1
 
 
 
|-
 
|-
 
|  
 
|  
 
TI_B2
 
TI_B2
 
 
 
|  
 
|  
 
Injection time for injectors in Bank2
 
Injection time for injectors in Bank2
 
 
 
|-
 
|-
 
|  
 
|  
 
TI_TVU_W
 
TI_TVU_W
 
 
 
|  
 
|  
 
Battery voltage-dependent
 
Battery voltage-dependent
 
injection time correction CPU quantization
 
injection time correction CPU quantization
 
 
 
|-
 
|-
 
|  
 
|  
 
TI_W
 
TI_W
 
 
 
|  
 
|  
 
Injection time
 
Injection time
 
 
 
|-
 
|-
 
|  
 
|  
 
TVSP_W
 
TVSP_W
 
 
 
|  
 
|  
 
Injection delay time depending on evtmod
 
Injection delay time depending on evtmod
 
 
 
|-
 
|-
 
|  
 
|  
 
TVU_W
 
TVU_W
 
 
 
|  
 
|  
 
Battery voltage correction
 
Battery voltage correction
 
 
 
|-
 
|-
 
|  
 
|  
 
UB
 
UB
 
 
 
|  
 
|  
 
Battery voltage
 
Battery voltage
 
 
 
|-
 
|-
 
|  
 
|  
 
VSFPSES
 
VSFPSES
 
 
 
|  
 
|  
 
Adjustment factor for intake manifold pressure
 
Adjustment factor for intake manifold pressure
 
for the injection application
 
for the injection application
 
 
 
|}
 
|}
  
 
[[Category:ME7]]
 
[[Category:ME7]]

Revision as of 08:03, 11 October 2011

u>RKTI 11.40 Function Description</u>


ti_w represents a physical value of injection time which is correct also during start conditions. During start the physical value of ti_b1, ti_b2 and ti_tvu_w has to be corrected by the user by a factor of 8, because start quantisation of ti_b1 is internally corrected by dividing by 8 to store large ti-values into a ‘word’ variable instead of a ‘long’ variable.


Please see the funktionsrahmen for the following diagrams:


1. Battery correction of injection time for injection valves, calculation frkte (fuel mass into injection time)

2. Calculation of ubatt correction of injector time for injectors

3. Correction for injected fuel mass if the reference pressure of the fuel rail pressure controller is not manifold pressure (i.e. with a returnless fuel rail).

4. Calculation of the injection time during start conditions

5. Calculation of the injection time after end of start conditions


This function calculates the effective injection time before fine tuning (tevfa_w, tevfa2_w) from the relative fuel mass (rk_w, rk2_w) and the factor frkte. With an ideal fuel supply system, tevfa_w + tvu_w, tevfa2_w + tvu_w should result in lambda of 1.0 in the combustion chamber, with pilot control to lambda = 1.0 and neutral values ​​of all mixture adaptations.


In practice, a deviation in lambda may occur due to injector nonlinearities or pulses in the fuel system. This deviation is corrected using the map FKKVS as a function of engine speed (nmot_w) and effective injection time (tevfa_w or tevfa2_w). The corrected effective injection time is te_w or te2_w. By adding the battery voltage correction for the injectors, the actuation time is calculated thus: ti_b1 = te_w + tvu_w. The function ACIFI controls the actuation times ti_b1 and ti_b2 for the associated injectors. In a single bank system (SY_stervk = false) the actuation times for bank 1 (ti_b1 or ti_b2) are forwarded to CIFI. In order to achieve the long injection times required during starting conditions, the quantization times ti_b1, ti_b2 are increased by a factor of 8 which thus expands the range to 1677.696 ms. The same applies for the additive quantity ti_tvu_w.


Therefore, a 16 bit value is required for the interface to the function ACIFI. This is important for runtime reasons for normal operation. During start conditions, VS100 measurements of the physically indicated injection time are multiplied by a factor of 8. The resolution during start conditions for ti_b1, ti_b2 and ti_tvu_w is 25.6 microseconds, whereas in normal operation it is 3.2 microseconds.


The RAM cells ti_w and ti_2_w show the physically correct injection time during both start conditions and also normal operation with a resolution of 16 microseconds. The resolutions are valid for a 20 MHz processor.


The minimum injection time TEMIN or TEMINVA is set when outputs B_va = true, B_temin = true or B_temin2 = true. This serves to lock out the lambda control. The threshold value TEMINVA is differentiated from TEMIN with a cold engine when the wall film degradation is not properly emulated by the thinning-delay because te_w limits TEMIN. At higher speeds it is possible that the available theoretical maximum injection time is not sufficient to obtain the required target torque. Therefore, an injection time timx_w that is larger than the maximum possible injection time timxth_w is deployed until the desired torque is withdrawn and timx_w is not larger than timxth_w. For this purpose, the control error dtimx_w is assigned to a PI controller. When the controller is active, the output controlled variable mitibgr_w represents the desired torque. When the controller is inactive, mitibgr_w receives the value 100%. The desired torque in %MDBGRG is obtained by initializing with mifab_w and mitibgr_w. In order to avoid jumps in the nominal torque, the integrator of the integral component is initialized with mifab_w.


The controller is activated as soon as timx_w exceeds the speed-dependent threshold timxth_w. The controller remains in operation until timx_w < timxth_w AND mitibgr_w > mifab_w. See Applications Information.


RKTI 11.40 Application Notes


Calculation of the constant KRKTE:


KRKTE = (rhoair x Vhcyl) / (100 x 14.7 x 1.67x10–5 x 1.05 x Qstat)


= (50.2624 x Vhcyl) / Qstat


Where:


rhoair = air density (1.293 g/dm3 at 0°C and 1013 mbar)

Vhcyl = Volume of a cylinder hub in dm3

Qstat = injector constant with n-heptane

1.05 = injector correction factor for petrol

14.7 = Stoichiometric air quantity at lambda = 1.0

1.67x10–5 = conversion factor minutes to milliseconds.


Calculation of the correction for fuel supply systems where the reference pressure of the fuel pressure regulator is ambient pressure:


FRLFSDP = SQRT[pdr_evmes/(pdr_akt + (pu - ps))]


Where:


pdr_evmes = absolute pressure in the fuel system before the injectors at the injector constant (Qstat) generally 3 bar

pdr_akt = actual fuel system pressure

pu = ambient pressure

ps = intake manifold pressure


For systems that take their reference pressure from the intake manifold pu - ps = 0 is used in the calculation above.


It then applies to the entire relationship FRLFSDP = Ö(pdr_evmes/pdr_akt)


For a fuel pressure of 3 bar, the results for FRLFSDP (where dpus = pu - ps) are as follows:


Naturally-aspirated Engine

Turbocharged Engine

dpus/mbar

FRLFSDP

dpus/mbar

FRLFSDP

0

1.0000

-1200*

1.2990

100

0.9837

-1000

1.2247

200

0.9682

-800

1.1678

300

0.9535

-600

1.1180

400

0.9393

-400

1.0742

500

0.9258

-200

1.0351

600

0.9129

0

1.0000

700

0.9005

200

0.9682

800

0.8885

400

0.9393

600

0.9129

800

0.8885

  • Boost pressure = 1800 mbar, ambient pressure = 600 mbar


For consistency reasons, 11 sampling points for vacuum and turbo are used with the turbo-values.


In the charge sampling and injection application in returnless fuel systems via the code word for the reference pressure for the fuel pressure regulator (CWPKAPP), the constant PSAPES (intake manifold pressure for injection application) is used as a substitute value where the modelled intake manifold pressure ps_w has not been applied. Thus the manifold pressure can be set directly with a VS100 processor. With the VS20 processor, the pressure PSAPES can be changed with an adjustment factor between 0 and 2 via the RAM cell vsfpses (pses_w = PSAPES x vsfpses).


The initial value for PSAPES is 1013 mbar. If this value (in conjunction with a factor of 2 from vsfpses) does not define the maximum manifold pressure for turbocharged engines with VS20, the one-off value of PSAPES must be increased with VS100.


Initialization:


Map size in program development nmot x tevfa_w = 10 x 10


FKKVS: Sample points


Speed

800

1400

2000

2600

3200

3800

4400

5000

5600

6200

RPM

Tevfa_w

1.5

2.5

3.5

4.5

5.5

6.5

7.5

8.5

9.5

10.5

ms

Value

1.0

1.0

1.0

1.0

1.0

1.0

1.0

1.0

1.0

1.0

The characteristic field FKKVS corrects errors in the fuel system (pulses in returnless fuel systems)


The map size of FKKVS can be extended to about nmot x tevfa_w = 10 x 10 to 16 x 10.


This is especially important to simplify the application for proportional systems. The speed ​​sample points ​​should match the number and values of the map KFPRG in the function BGSRM.


TEMIN: 1 milliseconds


TEMINVA: 1 milliseconds so that overall, the same TEMIN is active


TEMINVA: 0 milliseconds so that it is inactive when the engine is cold and thinning delay B_va = true, te to TEMIN seated and so that the wall film is not broken down properly.


ti-resolution values ​​are valid for a 20 MHz processor frequency. Otherwise thery must be converted thus: 20 MHz / (current processor frequency [MHz]).


Start:


ti_b1, ti_b2 25.6 microseconds. Measurements from VS100 must be multiplied by a factor of 8.

ti_tvu_w 25.6 microseconds. Measurements from VS100 must be multiplied by a factor of 8.

ti_w, ti2_w 16 microseconds.

te_w, te2_w not available.


Normal:


ti_b1, ti_b2 3.2 microseconds.

ti_tvu_w 3.2 microseconds.

ti_w, ti2_w 16 microseconds.

te_w, te2_w 3.2 microseconds.

First inputs:


ZTSPEV = 240 seconds

TVTSPEV

Etvmodev [°]

-20

0

100

120

tvsp_w [ms]

0

0

0

0

DMIL


CWDMIL


Bit 0 true: controller activated

Bit 0 false: controller deactivated

Bit 1 true: inputs B_ba and B_bag both active

KMITIBGR = 15 %/ms*s

PVMITIBGR = 0.8 %/ms


Variable

Description

CWDMIL

Code word ti-continuous wave control RKTI

CWPKAPP

Application code word for the fuel pressure regulator pressure reference

FKKVS

Correction factor for the fuel supply system

FRLFSDP

Injection correction RLFS

KMITIBGR

On-slope factor for the integration of dtimx_w through torque limitation

KRKTE

Conversion of relative fuel mass rk to effective injection time te

PSAPES

Intake manifold injection for application

PVMITIBGR

Proportional gain factor for torque limitation through continuous wave injection

SY_STERVK

System constant condition: stereo before catalytic converter

TEMIN

minimum TE

TEMINVA

minimum TE at VA

TVTSPEV

Correction of the injection time depending on evtmod

TVUB

Voltage correction

ZTSPEV

Time constant for filtering evtmod taking tvu-control into account

B_BA

Acceleration enrichment condition (indicator)

B_BAG

Strong acceleration enrichment condition

B_ENIMITI

Integrator release condition for torque limitation through continuous wave injection

B_STEND

End of start condition

B_TEMIN

TEMIN-limiting condition active, Bank 1

B_TEMIN2

TEMIN-limiting condition active, Bank 2

B_VA

Wall-film thinning delay condition (indicator)

DPUS_W

Delta intake manifold pressure environment

DTIMX_W

Difference between theoretical and maximum injection time

EVTMOD

Intake valve temperature models (temperature model)

EVTMODEV

Filtered value of evtmod taking into account the formation of tvu_w

FRKTE_W

Conversion factor relative fuel mass rk to effective injection time te

FTEK2_W

Correction factor for effective injection time, Bank 2

FTEK_W

Correction factor for effective injection time

MIFAB_W

Limited indexed driver-desired torque

MITIBGRI_W

I-component for torque limitation via ti-control during continuous injection

MITIBGRP_W

P-component for torque limitation via ti-control during continuous injection

MITIBGR_W

Torque limitation via ti-control during continuous injection

NMOT

Engine speed

NMOT_W

Engine speed

PS_W

Manifold Absolute Pressure (Word)

PU_W

Ambient pressure

RK2_W

Relative fuel mass, Bank2

RK_W

Relative fuel mass

TE2_W

Effective injection time Bank2 (word)

TEVFA2_W

Effective injection time before trim (word)

TEVFAKGE_W

Addressing map FKKVS with effective injection time before fine-tuning

TEVFA_W

Effective injection time before trim (word)

TE W

Effective injection time (word)

TI2_W

Injection time for cylinder 2 (word)

TIMXTH_W

Theoretical maximum injection time

TIMX_W

Maximum injection time

TI B1

Injection time for injectors in Bank1

TI_B2

Injection time for injectors in Bank2

TI_TVU_W

Battery voltage-dependent injection time correction CPU quantization

TI_W

Injection time

TVSP_W

Injection delay time depending on evtmod

TVU_W

Battery voltage correction

UB

Battery voltage

VSFPSES

Adjustment factor for intake manifold pressure for the injection application

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