View source for MDZW 1.120 (Calculating Torque at the Desired Ignition Angle)

<u>MDZW 1.120 Function Description</u>
  
When calculating the desired ignition angle there are three different cases:

1. Torque influence on the ignition angle active (B_zwvs = 1)
 
2. Switching off torque influence on the ignition angle (B_zwvs = 0, dmaufr_w&gt; 0)
 
3. Torque influences inactive (B_nozwe = 1)

  
<u>1. Active Torque Intervention</u>
 
The enable condition (B_zwvs) condition is set and the switch-off condition for the ignition angle intervention (B_nozwe) is false. The desired ignition angle is calculated from the torque requirement for the ignition path mizsol_w. The perturbation ramp (dmaufr_w) is zero. The requested torque mizsol_w is converted into the desired efficiency etazws. This is done by dividing by the optimum torque, which is calculated by multiplying miopt_w with the efficiency etazaist. The desired efficiency (etazws) is converted via the inverse ignition angle efficiency characteristic DZWETA into a delta-ignition angle (dzws). The difference between the optimum ignition angle zwopt and dzws gives the desired ignition angle zwsol.

  
<u>2. Switching off the Torque Influence</u>

When switching off the torque intervention (B_zwvz = 1®0, see %MDKOG), the desired torque mizsol_w can jump to a higher value. This positive torque perturbation must be prevented for driveability reasons. This is done by eliminating the requirement B_zwvz. A perturbation ramp dmaufr_w is reset, which initialises the amplitude of the jump and runs down to zero with a speed-dependent rate. This ramp is subtracted from the input mizsol_w and ensures a smooth transition into a state without any intervention within the timeframe. In this state B_zwvs = false, the switch-off condition for the ignition angle intervention B_nozwe is set but only after the ramp.

  
A special case is the anti-judder feature intervention, in which B_zwvs, but not B_zwvz is set. When the anti-judder torque requirement is eliminated from input mizsol_w, there is no jump, so that the switch-off ramp in this case is not necessary.

  
<u>3. Torque Influences Inactive</u>


In this state, no requirement is active (B_zwvs = 0) and the ramp dmaufr_w is screened. The switch-off condition for the ignition angle intervention B_nozwe is set. In this case, the desired ignition angle zwsol for the ignition is not taken into account (c.f. %ZUE) so the calculation can be omitted.

  
<u>MDZW 1.120 Application Notes</u>

  
The values &#8203;&#8203;are in DMAUFN are preset to give a slope of approximately 5%/sec for all engine speeds.

<u>Abbreviations</u>
                                                                                 
{| border="1"
|-
| 
Parameter
| 
Description
|-
| 
DMAUFN
| 
Delta torque control after engine torque intervention
|-
| 
DZWETA
| 
Inverse delta ignition angle efficiency
|-
| 
Variable
| 
Description
|-
| 
B_NOZWE
| 
Condition flag: no ignition angle intervention on the engine torque
structure
|-
| 
B_ZWVS
| 
Condition flag for fast external ignition angle intervention on the
torque interface
|-
| 
B_ZWVZ
| 
Condition flag for ignition angle intervention on the torque interface
|-
| 
DMAUFR_W
| 
Delta “up regulation” torque
|-
| 
DZWS
| 
Delta ignition angle between zwopt and zwsol
|-
| 
ETAZAIST
| 
Actual cylinder suppression efficiency
|-
| 
ETAZWS
| 
Desired ignition angle efficiency
|-
| 
MIBAS_W
| 
Indicated basic torque
|-
| 
MIOPT_W
| 
Optimum indicated torque
|-
| 
MISOL_W
| 
Indicated resulting desired torque
|-
| 
MIZSOL_W
| 
Indicated resulting desired torque for ignition angle intervention
|-
| 
MIZWMN_W
| 
Indicated engine torque at the latest ignition angle
|-
| 
NMOT W
| 
Engine speed
|-
| 
REDIST
| 
Actual reduction stage
|-
| 
R SYN
| 
Synchronisation grid
|-
| 
ZWOPT
| 
Optimum ignition angle
|-
| 
ZWSOL
| 
Desired ignition angle for torque intervention
|}

[[Category:ME7]]