Difference between revisions of "MDKOG 14.70 (Torque Coordination for Overall Interventions)"

Revision as of 15:11, 29 September 2011

See the funktionsrahmen for the following diagrams:

mdkog-main Main function overview

mdkog-bbmdein Sub-function BBMDEIN: active torque intervention conditions

mdkog-bbzwein Sub-function BBZWEIN: active ignition angle intervention conditions

mdkog-mdbeg Sub-function MDBEG: limit of the indicated torque

mdkog-mdbeg-diag Sub-function MDBEG_DIAG: connection of the torque limit to the diagnosis

mdkog-mdabws Sub-function MDABWS: stalling

MDKOG 14.70 Function Description

Coordination of the Requested Engine Torques

Through the torque coordination calculation, the indexed desired engine torque (misol_w) is used to calculate the fade out stage and/or the ignition angle adjustment. The externally-requested indexed torques from the cruise control (miasrs_w) and transmission protection (migs_w) and the internal torque requirements (e.g. driver requested torque, maximum engine speed or maximum load) will be converted into an indexed desired engine torque (misolv_w) via either a minimum or maximum range.

The desired torque for the ignition path is dependent on the enable condition B_zwvz (cf. BBMDEIN):

- When ignition angle interventions are enabled, mizsolv_w is calculated as follows:

The upper limit of the desired torque, misolv_w, is given by the product of optimal internal torque (including lambda influence) and ignition angle (miopt_w ´ etazwb), then the torque requirements of the idle control dmllr_w (only proportional and differential components) and the anti-judder feature, dmar_w are added.

- When ignition angle interventions are not required, the basic torque mibas_w is used as the desired torque which depends only on the stipulated ignition and mixture-application efficiencies. The anti-judder feature intervention is also considered in this case.

Sub-function BBMDEIN: Active Torque Intervention Conditions

In addition, via the traction control torque intervention, the condition flag B_msr is set so that overrun fuel cut-off is prohibited (see %MDRED). During cruise control intervention, the condition flag B_asr to cylinder suppression is possible (see %MDRED). The condition flag B_mdein is used to disable the misfire detection (see %DASE) and enable the anti-judder feature or idle speed control (for B_mdein = 0). The condition flags B_zwvz and B_zwvs are responsible for enabling the torque adjustment through ignition.

- B_zwvz is set when the time frame level detects the need for an intervention. This is the case at all operating points which require a torque reserve, i.e. idle, catalyst heating, short journeys and for the dashpot driveability functions, load shock attenuation, filtering for overrun fuel cut-off and short journeys. When the clutch is also immediately released to avoid revving the engine. All external intervention is detected by comparing mifa_w and misol_w.

An ignition angle enable can also be made via the code word CWMDKOG, when the desired the cylinder charge corresponds to the minimum cylinder charge. In addition, if the difference between the actual cylinder charge and the minimum cylinder charge is less than the delta value to be applied, data input to the code word for the ignition angle can be enabled.

- B_zwvs is set when either a timeframe intervention is submitted or a torque influence from the anti-judder feature is required. The desired value is not then switched to misol_w in the function %MDZW (torque influence on ignition), however, the influence is activated.

Sub-function MDABWS: Stalling

Should the engine speed during torque reduction through cruise control or transmission protection fall under NASNOTTM, miext is immediately set equal to MDIMX so that the two operations are prohibited. NASNOTKL is a function of engine temperature, tmot.

Sub-function BBZWEIN: Active Ignition Angle Intervention Conditions

see BBMDEIN

Sub-function MDBEG: limit of the indicated torque

The two torque variables and misolv_w mizsolv_w are limited to the maximum indicated torque miszul_w (from %MDZUL). This is to ensure that monitoring in level 2 only becomes active when the desired (and possibly limited) torque is not converted correctly into an actual torque. The data input to KFMIZU will be aligned to the level 2 permitted torque. Particularly in the application phase this can prevent an unwanted torque monitoring response. By noting the value of B_mibeg it is possible to detect whether a limitation of the desired torque has been made.

To test the data monitoring, there is a counter cmibeg_w that counts the number of active limitations. The counter cmibeg_w is incremented with each rising edge of B_mibeg. The counter is not active when the driver releases the throttle pedal or the maximum value is reached (MAXWORD = 65,535). The value is cached and only an error path enable or a power failure resets it.

Sub-function MDBEG_DIAG: Connection of the Torque Limit to the Diagnosis

This function MDBEG_DIAG is part of the EGAS monitoring concept (level 1). The desired torque MDBEG is limited to a maximum permissible torque, miszul_w. If this limit is active, the bit B_mibeg is set. In certain operating conditions (e.g. very cold engine and idle), this level-1-limit will be active, but only for a short time. If the limit B_mibeg is active for a longer time (e.g. 10 minutes), there might be a fault in the system and a diagnostic entry is made.

MDKOG 14.70 Application Notes

Typical values:

MDIMX = 99.6%;

NASNOTKL

The engine speed threshold NASNOT must not be larger than 2550 rpm.

DELRL < 2%

THDMB = 1 sec

CWMDKOG = 2

Note 1. Ignition angle enable with rlsol = rlmin

Note 2. Ignition angle enable with B_mibeg

Note 3. Ignition angle enable with rl - rlmin_w £ DELRL

Note 4. !B_mibegl kill data input