Overview
This document contains information on:
General
Function
General
For engines with integrated starter alternator (ISA), idle speed control is primarily done via the integrated starter alternator (ISA). If not all of the conditions required for correct operation of the integrated starter alternator (ISA) are met, the conventional rpm control takes over idle speed control. The transition from the closed-loop control via the integrated starter alternator (ISA) to conventional rpm control cannot be detected by the driver.
Function
Depending on the operating mode, the idle speed is set to a certain specified value. The energy requirements of the on-board electrical system are met by the generator function of the integrated starter alternator (ISA). The torque to be provided is specified to the combustion engine. From here, the integrated starter alternator (ISA) picks up the required portion and supplies the on-board electrical system and on-board electrical system battery with energy.
This means that more energy can be generated by the integrated starter alternator (ISA) and the needs of the on-board electrical system can be covered.
If consumption is increased, e.g. by switching on the air conditioning, the 48 V on-board electrical system battery buffers the consumption.
If the 48 V on-board electrical system is overloaded at the current engine speed, the target engine speed is raised.
Extract of enable conditions |
Enable conditions |
Idle speed control mode requested. |
Actual speed does not deviate too far from the target engine speed or a drive program switching via the program was active. |
No load mode due to system error. |
Current electric motor torque does not deviate too far from the specified charging torque. |
Accelerator pedal value lower than threshold. |
Coolant temperature above threshold recorded in the system. |
Torque converter lockup clutch is open. |
No VM stop is available. |
No downhill slope detected. |
Temperature of 48 V on-board electrical system battery above threshold. |
Minimum possible electric motor torque with offset to required idle speed control electric motor torque. |
The charge request is higher than the threshold. So that the electric motor does not switch back and forth between positive and negative torque. |
Engine speed must be within the rpm band for a certain period of time. |
After termination of the idle speed control, the idle speed control should be deactivated for a parameterizable period of time. |
Stalling protection incorrectly active following start. |