Electronic Accelerator Function - GF30.20-P-3015MMK

Engine 276.8 in model 222.163/173 

Engine 276.9 in model 222 

Function requirements for the electronic accelerator, general points 

• Circuit 87M (Engine management ON)
• Internal combustion engine running

Electronic accelerator, general points 

The electronic accelerator function is integrated in the ME-SFI [ME] control unit (N3/10) and controls the drivetrain torque depending on the driver command and the operating conditions.

Drivetrain torque

On vehicles with internal combustion engine without hybrid drive, the drivetrain torque is the torque from the internal combustion engine which is transmitted to the drivetrain via the crankshaft.

On vehicles with hybrid drive, the torques from the internal combustion engine and the electrical machine (A79/1) are added together, resulting in a drivetrain torque.

The ME-SFI [ME] control unit regulates the drivetrain torque according to the following sensors and signals:

• Accelerator pedal sensor (B37), accelerator pedal position
• Brake actuation, cruise control request and torque request from the Electronic Stability Program control unit (N30/4) via chassis FlexRay (Flex E), powertrain control unit (N127) and drive train CAN (CAN C1)
• Torque request (increase or reduction) from radar sensors control unit (N62/1) (up to model year 2018) (with code P20 (Driver assistance package Plus)) via chassis FlexRay, powertrain control unit and drive train CAN
• Torque request (increase or reduction) from Mercedes-Benz Intelligent Drive control unit (N62/4) (from model year 2018) via chassis FlexRay, powertrain control unit and drive train CAN
• Gear range and reverse travel signal from fully integrated transmission control unit (Y3/8n4) via drive train CAN

The requirements of the torque coordination function are also taken into account.

Function sequence for electronic accelerator 

The function sequence is described in the following steps:

• Function sequence for drivetrain torque specification 
• Function sequence for drivability functions 
• Function sequence for reverse travel 
• Function sequence for adaptive accelerator pedal 
• Function sequence for haptic accelerator pedal module (for engine 276.8) 

Function sequence for drivetrain torque specification 

The ME-SFI [ME] control unit controls the drivetrain torque based on a characteristics map depending on the accelerator pedal sensor. To do so, the ME-SFI [ME] control unit actuates the following assembly parts in driving operation with the internal combustion engine or in hybrid driving mode:

• Actuator motor (M16/6m1) in the throttle valve actuator (M16/6) by means of a pulse width modulated signal
• Ignition coils (T1) for regulation of the ignition angle efficiency (results from shifting of the actual ignition angle from the optimal ignition angle) via the ignition timing.
• Fuel injectors (Y76) to regulate the lambda value over the fuel quantity
• Boost pressure control pressure transducer (Y77/1) for regulation of the boost pressure (for engine 276.8)

In as far as the traction is not exclusively realized by the internal combustion engine, for example in hybrid driving mode or electric operation (cruising mode, maneuver), the ME-MFI [ME] control unit makes the request from power electronics control unit (N129/1) for a specified torque from the electrical machine.

The drivetrain torque is only determined exclusively from the accelerator pedal position if no limited or increased torque requests from other functions or control units (e.g. cruise control request) are active. The actual value potentiometers 1 and 2 (M16/6r1, M16/6r2) report the current throttle valve position to the ME-SFI [ME] control unit.

Function sequence for drivability functions 

The driveability functions and throttle change damping have the task of limiting the change of drivetrain torque as a result of a rapid movement of the accelerator pedal. The limitation serves to improve the ride comfort since jolting in the drivetrain is prevented.

On vehicles with hybrid drive, dynamic torque interventions are not implemented exclusively using the torque reserve of the internal combustion engine. The ME-SFI [ME] control unit initially implements torque interventions in the current drivetrain torque via the electrical machine. To do this it requests the motor-generated torque from the electrical machine from the power electronics control unit via the CAN in order to increase the torque. Reducing torque interventions are realized through requests for a generated torque.

The power electronics control unit implements these requests and reports back the torque generated in this manner via the CAN to the ME-SFI [ME] control unit. If the torque interventions of the electrical machine are not sufficient then the torque from the internal combustion engine is additionally reduced or increased (torque reserve).

The drivability functions and the throttle change damping take place on the basis of the following sensors and signals:

• Accelerator pedal sensor, accelerator pedal actuation (fast, slow)
• Crankshaft Hall sensor (B70), engine rpm
• Coolant temperature sensor (B11/4)
• Left and right oxygen sensor elements upstream of catalytic converter (G3/3b1, G3/4b1)
• LH and RH oxygen sensor elements downstream of catalytic converter (G3/5b1, G3/6b1)
• Electronic Stability Program control unit, vehicle speed over suspension FlexRay, powertrain control unit and drive train CAN

Function sequence for reverse travel 

If the fully integrated transmission control unit sends the CAN signal "reverse travel" via drive train CAN, the vehicle speed is limited to 60 km/h by the ME-SFI [ME] control unit. This optimizes driving safety during reverse travel.

Function sequence for adaptive accelerator pedal 

The ME-SFI [ME] control unit changes the response time of the accelerator pedal depending on the vehicle speed calculated from the wheel speed. At higher vehicle speeds a somewhat steeper accelerator pedal curve is used in order to improve the response time (reduction of the free travel).

Function sequence for haptic accelerator pedal module (for engine 276.8) 

The accelerator pedal module control unit (B37n1) has the task to give the driver haptic feedback about the accelerator pedal. The driver is signaled dependent on the driving situation concerning which pedal angle is to be selected in order to allow the following functions in electric operation.

Metering electrical drive 

For the function "Metering electrical drive" the accelerator pedal module actuator motor (B37m1) generates noticeable actuation point on the accelerator pedal, which is signaled to the driver, until the pedal angle which achieves purely electrical driving is realized. If this angle piece is exceeded on the accelerator pedal, switching-in of the internal combustion engine takes place and the vehicle is located in hybrid driving mode.

The position of the accelerator pedal module actuator motor is detected by the accelerator pedal module sensor (B37b1) and reported to the accelerator pedal module control unit.

Foresighted electrical cruising 

By means of a double impulse from the accelerator pedal module actuator motor the driver receives the recommendation to release the accelerator pedal and to initiate the function "Foresighted electrical cruising" or also decel mode. The double impulse is triggered dependent on the speed of the vehicle and the distance to a vehicle immediately ahead.

	Electrical function schematic for electronic accelerator		PE30.20-P-2050-97SEC
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