Bosch ME7.1: Difference between revisions

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ME7 is a [[load]] based engine management system.
ME7 is a [[load]] based engine management system.


ME7 continuously calculates the "nominal charging moment" (requested torque) that the user seems to be requesting. This, in turn generates a "requested [[load]]" (nominal charge), which is capped by "specified corrected [[load]]" (a function of RPM, IAT and other limiting parameters, such as knock control, etc.). This requested [[load]] determines the throttle plate angle and requested pressure.
ME7 continuously calculates the "nominal charging moment" (requested torque) that the user seems to be requesting. This, in turn generates a "requested [[load]]" (nominal charge), which is capped by "specified corrected [[load]]" (a function of RPM, IAT and other limiting parameters, such as knock control, etc.). This requested [[load]] determines the throttle plate angle and requested pressure. As long as lambda control stays closed loop, the ECU will adjust the fuel mixture via feedback loop using the narrow-band O2 sensors.


Once the ECU decides the requested (or actual?) [[load]] is large enough(?), and/or the requested AFR deviates far enough from lambda 1(?), its fueling control system goes [[open loop]]. In the [[ME7.1]] [[asynchronous path]], this means that injector on-time calculations are going to be dependent on [[Mass air flow|mass air flow sensor]] readings. Those [[mass air flow|MAF]] readings also go into the fueling maps as a "engine [[load]]" and are used to generate injector on times independent of O2 sensor readings.
Once the ECU decides the [[load]] is large enough for enough time, or the requested AFR is no longer lambda=1, its fueling control system goes [[open loop]]. In the [[ME7.1]] [[asynchronous path]], this means that injector on-time calculations are going to be dependent on [[Mass air flow|mass air flow sensor]] readings. Those [[mass air flow|MAF]] readings also go into the fueling maps as a "engine [[load]]" and are used to generate injector on times independent of O2 sensor readings.


In the ME7.1 [[synchronous path]], the timing maps determine the timing at every cycle of every cylinder, and should the knock sensor for a given cylinder reach a certain threshold, the timing will be cut down for the next cycle for that cylinder. If the knock sensor activity subsides, the timing will be restored, one step at a time, until another knock event occurs on that cylinder.
In the ME7.1 [[synchronous path]], the timing maps determine the timing at every cycle of every cylinder, and should the knock sensor for a given cylinder reach a certain threshold, the timing will be cut down for the next cycle for that cylinder. If the knock sensor activity subsides, the timing will be restored, one step at a time, until another knock event occurs on that cylinder.

Revision as of 07:40, 23 January 2011

The Bosch ME7.1 Engine Control Unit (ECU) appears to use two 16bit Infineon B59233-FA (aka SAK-C167CR-4RM) CPUs. Non-volatile code/data is stored on a single 16bit Am29F800BB 44 pin PSOP flash device.

ME7 is a load based engine management system.

ME7 continuously calculates the "nominal charging moment" (requested torque) that the user seems to be requesting. This, in turn generates a "requested load" (nominal charge), which is capped by "specified corrected load" (a function of RPM, IAT and other limiting parameters, such as knock control, etc.). This requested load determines the throttle plate angle and requested pressure. As long as lambda control stays closed loop, the ECU will adjust the fuel mixture via feedback loop using the narrow-band O2 sensors.

Once the ECU decides the load is large enough for enough time, or the requested AFR is no longer lambda=1, its fueling control system goes open loop. In the ME7.1 asynchronous path, this means that injector on-time calculations are going to be dependent on mass air flow sensor readings. Those MAF readings also go into the fueling maps as a "engine load" and are used to generate injector on times independent of O2 sensor readings.

In the ME7.1 synchronous path, the timing maps determine the timing at every cycle of every cylinder, and should the knock sensor for a given cylinder reach a certain threshold, the timing will be cut down for the next cycle for that cylinder. If the knock sensor activity subsides, the timing will be restored, one step at a time, until another knock event occurs on that cylinder.

Block diagram of the torque (load) based system's control flow:

ME7.1 torque oriented.png

References

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