Driving, Function - GF08.30-P-2002RFH
Engine 274.920 in model 205.047/147/247
Engine 274.920 in model 205.053/054/253
Engine 274.920 in model 253.353/953
Engine 274.920 in model 253.354/954
Engine 651.921 in model 205.012/212
Engine 654.920 in model 205.013/213
Driving mode
The vehicle only uses electricity to drive, depending on the power requirement, the charge level of the high-voltage battery (A100g1) and the selected operating mode (model 205.047/147/247, 253.354/954). With a high power requirement, the combustion engine is started using a procedure developed specifically for hybrid drives with direct-injection spark-ignition engines and then rapidly and comfortably switched-in by means of driving condition-dependent actuation of the wet clutch (NAK) or engine separator clutch. When doing this, the Mercedes-Benz starting procedure uses a combination of suitable starter actuation and so-called direct starting of direct-injection gasoline engines for which the start is optimized by means of targeted injections and ignitions.
This and simultaneous automatic addition of the wet clutch or engine separator clutch with an appropriate additional acceleration effect on the starting combustion engine make it possible for the hybrid vehicle to start extremely quickly compared to a conventional starting process. This optimizes starting process ensures rapid connection of the drive from the electrical drive.
The various driving conditions during driving can be differentiated between as:
- Hybrid mode
- Electric mode
- Recuperation
- BOOST MODE
Hybrid mode
In hybrid mode, the internal combustion engine acts as the main drive source. The electric machine (A79/1) is used in alternator mode to supply on-board energy consumers such as the air conditioning system or to charge or top up the high-voltage battery. It is only in cases of strong acceleration that the internal combustion engine supports the electric machine in so-called boost mode and therefore ensures maximum output and torque at the level on an 8 cylinder engine.
The internal combustion engine is switched off however dependent on the power requirement of the drive and the onboard network consumers as well as from the charge level of the high-voltage battery, in order in turn to go back to electrical operation.
Electric mode
If the transmission mode or the operating mode of electrical drive allows it, the charge level of the high-voltage battery is high enough, the torque request of the driver can be fulfilled purely electrically and no diagnosis or no system error will prevent electrical operation, then this operating condition is adopted. The wet clutch or the engine separator clutch is opened and the combustion engine is switched off by the ME-SFI [ME] control unit if certain prerequisites are fulfilled.
Recuperation
For the HVs the Premium ESP® system was modified in such a way that the hydraulic connection between the master brake cylinder and rear axle brake circuit is locked out over a separation valve in the ESP® system for RBS in fault-free operation. This means that the rear axle cab either be braked over the electric machine or over the hydraulic unit.
For regenerative braking, only a part, or at low braking the entire braking torque is generated by the electric machine. The high-voltage battery is charged with the electrical energy produced in the process.
BOOST MODE
In boost mode the electric machine supports the internal combustion engine in order to reach the requested specified torque as quickly as possible or to further amplify the drive torque to amplify the maximum achieved internal combustion engine torque.
The duration and intensity of the boost mode are hereby dependent on the charge level of the high-voltage battery and the position of the accelerator pedal. Torque synchronization between the combustion engine and the electric machine is realized in boost mode during driving off via appropriate actuation of the wet clutch or engine separator clutch.
Operating mode and transmission modes (model 205.047/147/247, model 253.353/354/953/954)
In order to use the vehicle in an optimum way in accordance with the driver's requirements and the driving profile, three transmission modes and four operating modes are available to the driver, which can be selected manually.
Over the AGILITY SELECT switch (N72/4s1) (model 205 up to model year 2016, except model 253) or DYNAMIC SELECT switch (N72/4s11) (model 205 as of model year 2016, model 253) the following transmission mode can be selected:
- Comfort
- Sport
- SPORT PLUS
- Individual
- ECO
The AGILITY SELECT switch (model 205 up to model year 2016, except model 253) or DYNAMIC SELECT switch (model 205 as of model year 2016, model 253) is in the LCP on the left (N72/4). Its status is read in by the touchpad (A105) (with code 446 (Touchpad only)) or by the Audio/COMAND control panel (A40/9) (without code 446 (Touchpad only)) via the LCP-LIN (LIN A3) and passed on to the instrument cluster (A1) and powertrain control unit (N127) via the CAN network. The powertrain control unit sets the transmission mode and the IC shows the set transmission mode.
Comfort
Driving in hybrid mode with propulsion, also in electric mode
Sport
For sporty driving the internal combustion engine is always switched on.
SPORT PLUS
For particularly sporty driving the internal combustion engine is always switched on.
Individual
In the transmission mode Individual the properties of the vehicle systems can be set by the driver himself.
ECO
Driving in hybrid mode with a route-based operating strategy and extended decel mode
Sailing mode
In the "ECO" transmission mode, the overrun torque that occurs during electrical operation is reduced to a minimum, which allows maximum use of cruising mode. In this way the vehicle can cover a further travel distance rolling when releasing the accelerator pedal.
Strong braking after a longer stretch in cruising mode or cruising mode occurring too early with subsequent renewed support by the internal combustion engine is disadvantageous. For this reason, a haptic accelerator pedal was installed for the ECO assistant.
When using the radar sensor system installed in the vehicle, the clearance and the speed to the vehicle driving immediately ahead are recognized. In the very moment in which release of the accelerator pedal leads to consumption-optimized matching of the speed to a vehicle driving immediately ahead, the ECO assistant engages. Based on the noticeable double impulse in the haptic accelerator pedal, the driver receives a recommendation to release the accelerator pedal. As soon as the pedal is released, the combustion engine is switched off when electric mode is available, decoupled over the wet clutch or engine separator clutch from the drivetrain and the vehicle switches into cruising mode.
If the vehicle driving immediately ahead reduces its speed or if the clearance to it reduces due to other factors, the radar-based thrust control engages. Through adaptation of the thrust torque of the electric machine the clearance to the vehicle driving immediately ahead is compensated for according to the driving situation.
The following table gives an overview of which transmission mode is selectable in the respective operating mode and how the operating energy input is generated.
| Mode | Operating energy input | Comfort | Sport | SPORT PLUS | Individual | ECO |
|---|---|---|---|---|---|---|
| (HYBRID) | Internal combustion engine + electric machine | Selectable | Selectable | Selectable | Selectable | Selectable |
| E-MODE | Electric machine | Selectable | Not selectable, internal combustion engine running. | Not selectable, internal combustion engine running. | Selectable | Selectable |
| E-SAVE | Combustion engine | Selectable | Not selectable, internal combustion engine running. | Not selectable, internal combustion engine running. | Selectable | Selectable |
| CHARGE | Combustion engine | Selectable | Not selectable, internal combustion engine running. | Not selectable, internal combustion engine running. | Selectable | Selectable |
Over the "Select operating mode" button (N72/5s16) (model 205 up to model year 2016, except model 253) or "Select operating mode" button (N72/4s6) (model 205 as of model year 2016, model 253) the following operating modes can be selected by pressing a button:
- (HYBRID)
- E-MODE
- E-SAVE
- CHARGE
While the handling characteristics can be essentially set by the transmission mode, the operating mode offers the opportunity to use the electrical energy and therefore to have an immediate influence on the charge level of the high-voltage battery.
The operating mode selection button is located on the LCP on the right (N72/5) (model 205 up to model year 2016, except model 253) or LCP on the left (model 205 as of model year 2016, model 253). Its status is read in by the touchpad (with code 446 (Touchpad only)) or by the Audio/COMAND control panel (without code 446 (Touchpad only)) and passed on to the instrument cluster and powertrain control unit via the CAN network. The powertrain control unit sets the operating mode and the instrument cluster shows the set operating mode.
(HYBRID)
The operating mode HYBRID is the default operating mode. In the transmission modes it offers the hybrid mode with a load condition dependent driving part electrical operation and a maximum additional start comfort through retention of appropriate reserve power for the electric machine.
The "Sports" and "Sport Plus" transmission mode is set for maximum responsiveness and, besides changes in the gear selector of the transmission and the design of the accelerator pedal curve, electrical operation is dispensed with altogether and the boost output is increased.
Route-based operating strategy
The various manually selectable operating modes are used by the driver since he knows his route and knows where he wishes to drive electrically and when the high-voltage battery should be discharged.
The route-based operating strategy accommodates these two desires and combines them with the comfort that the driver can be relieved of the decision-taking concerning the route-optimized sequence of the operating mode while taking account of map data.
The selection of the operating mode does not take place purely event-oriented but rather also while taking account of the following:
- The use of electrical energy has differing consumption-reducing effects depending on the route that is being driven.
- The use of electrical energy for electrical operation in a city represents a high emotional additional benefit for the driver.
For highway driving one can, for example, use less electrical energy dependent on need with a route-based operating strategy, and the charge level of the high-voltage battery can also be adjusted in a targeted manner to the remaining stretches, through load-point shifting.
The following fundamentals are necessary for the energy assessment of the router and therefore for the charging control and performance enabling:
- COMAND Online
- On-board electrical system consumption
Actuation of the hybrid drive system
E-MODE
The operating mode E-MODE stands for maximum electrical operation. In order to allow the driver comfortable continuation of driving in electrical operation, the haptic accelerator pedal is activated with an over-center preload. When this occurs, a noticeable actuation point is output via the accelerator pedal just before the request to start the internal combustion engine. The start is not carried out until the actuation point has been passed.
E-SAVE
In operating mode E-SAVE the charge level of the high-voltage battery which was stored upon activation of the operating mode is maintained. Part of the electrical drive continues to be permitted. It is therefore still possible to switch off the engine at a standstill or in deceleration mode to prevent consumption while idling. Just as enough energy is taken from the high-voltage battery that the charge level does not fall below the set value.
CHARGE
In the operating mode CHARGE, the high-voltage battery is moderately supercharged in driving mode by load capacity increase of the internal combustion engine. In order to secure continuous charging operation one dispenses with all electrical operation and the boost mode. Just as soon as the high-voltage battery has been completely supercharged, there is automatic changeover into the operating mode E-SAVE.
The driving operation of the hybrid drive system and the active subfunctions are described in the following documents:
- Deceleration mode, function
- Hybrid drive system test conditions, function
- Automatic engine stop, function
- Automatic engine start, function
- Torque coordination for a hybrid drive system, function
- Monitoring a hybrid drive system, function
- Recuperative braking, function
| Deceleration mode, function | GF08.30-P-2004RFH | ||
| Hybrid drive system test conditions, function | GF08.30-P-2005RFH | ||
| Automatic engine stop, function | GF08.30-P-3001RFH | ||
| Automatic engine start, function | GF08.30-P-3002RFH | ||
| Torque coordination for a hybrid drive system, function | GF08.30-P-4001RFH | ||
| Monitoring a hybrid drive system, function | GF08.30-P-5001RFH | ||
| Recuperative braking, function | GF42.22-P-1010RFH | ||
| Overview of system components, hybrid drive system | GF08.30-P-9999RFH |