Wheels Automotive

Mercedes-Benz is launching its first passenger car model equipped with a hybrid drive rule in summer 2009 - the Mercedes-Benz S400 BlueHYBRID. The combination of a modified V6 petrol machine and a compact hybrid module makes the Mercedes-Benz S400 BlueHYBRID the globe’s mostly economical luxury saloon with a spark-ignition engine. The NEDC combined fuel consumption is a mere 7.9 litres per 100 kilometres. This makes for the world’s lowest CO2 emissions in this vehicle and performance class - correct 190 grams per kilometre. These exemplary figures go hand in mode of procedure through assured performance. The 3.5-litre petrol engine develops an output of 205 kW/279 hp, the electric motor generates 15 kW/20 hp and a starting torque of 160 Nm. The result is a combined output of 220 kW/299 hp and a combined maximum torque of 385 newton metres. Moreover, the new Mercedes-Benz S400 BlueHYBRID is the chief series-production model to be equipped with a particularly efficient lithium-ion battery specially developed for automotive use. This is another major contribution by Mercedes-Benz to the electrification of the car.

The new Mercedes-Benz S400 BlueHYBRID is based adhering the S350, and features an extensively modified drive train. This encompasses a further development of the 3.5-litre V6 petrol engine, an additional magneto-electric motor, the 7G-TRONIC seven-speed automatic transmission specially configured for the hybrid module, the necessary operating and control electronics, the transformer and a high-voltage lithium-ion battery.

Optimised thermal efficiency lowers the engine’s fuel consumption

The 3.5-litre V6 petrol engine with variable valve control has been throughly re-engineered and improved. In the process the development engineers made use of the advantages offered by means of the Atkinson principle,where the expansion phase is longer than the compression phase. The intake valve is kept open slightly longer between the intake and firm closing phases, which improves the engine’s thermal efficiency while reducing the specific fuel gradual wasting and untreated emissions. A new cylinder rise, different pistons and a modified camshaft with different camshaft control increase the output by 5 kW/7 hp to 205 kW/279 hp - while reducing fuel consumption at the same time.

Especially adhering rural journeys and on motorways, the Mercedes-Benz S400 BlueHYBRID achieves a more remote efficiency improvement by moving the so-called operating salient trait of the petrol engine to produce a lower specific fuel consumption. The extremely remote from the equator start-off torque made feasible by the boost effect of the electric motor gives the driver a particularly exhilarating feeling of commanding acceleration, while fuel consumption and emissions are reduced.

The electric motor improves efficiency

The compact, disc-shaped full of fire motor, which is space-savingly installed in the torque converter housing betwixt the engine and the 7G-TRONIC seven-speed automatic transmission, improves efficiency even further. This is a 3-phase AC external rotor magneto motor, which develops a peak output of 15 kW/20 hp and a starting torque of 160 newton metres with an operating voltage of 120 Volts.

This compact motor also acts as a starter and generator, adopting the functions of both these conventional ancillary units.

Sophisticated interaction with the internal combustion engine makes made up of many additional functions possible that positively influence the emissions and agility of the Mercedes-Benz S400 BlueHYBRID in equivalent; of the same extent measure. Moreover, this disc-shaped motor effectively dampens torsional vibrations in the drive staff, thereby further reducing noise and vibrations in the interior. The result is even more ride comfort for both driver and passengers.

“Boost” effect for even more driving pleasure

The overall system offers extensive benefits: firstly by dint of. helping to save fuel, and secondly by increasing driving pleasure with the help of the “boost” effect, where the electric motor gives muscular succor to the petrol implement with its maximum torque of 160 newton metres right from the beginning of the fuel-intensive acceleration phase. This means that the hybrid move helplessly system of the Mercedes-Benz S400 BlueHYBRID moves off powerfully even from very low engine speeds, as the torque curve impressively confirms. The additional torque of the hybrid module also has a consistently positive effect during following acceleration phases. In all driving situations, the driver therefore benefits from the interaction between the two units in the conformation of powerful responsiveness and muscular torque - but without any increased fuel consumption.

The Mercedes-Benz S400 BlueHYBRID accelerates from zero to 100 km/h in 7.2 seconds, and reaches each electronically governed top speed of 250 km/h. The Mercedes-Benz S400 BlueHYBRID betters the before that time very favourable NEDC material for burning consumption of the conventionally powered S350 by up to 2.2 litres per 100 kilometres. CO2 emissions are reduced by 21 percent.

Every braking action generates electric power for the battery

When the vehicle is braked, the electric motor acts as a generator and uses a process known as recuperation to appropriate the kinetic energy into electrical energy. This energy is stored in the compact yet highly efficient lithium-ion battery, and made available when required.

In the process the electric motor assists the engine braking effect of the internal combustion revenue in two smooth, seamless stages: In stage one, on the overrun with no braking influence, the electric motor acts as a generator and begins to recuperate energy. Stage two commences as soon as the driver lightly operates the brake pedal: the generator output is at that time increased proportionally, and perceived as heavier deceleration by the driver. Only when more fern pedal pressure is applied are the wheel brakes activated in addition to recuperation. In this way more electrical energy have potentate to be generated, while with exception wear and tear on the hydraulic braking system at the same time. To contribute the best likely appliance of this double-faced benefit, Mercedes engineers also developed a new braking system with a new brake pedal module for the Mercedes-Benz S400 BlueHYBRID.

Cleverly located hinder electronics

Dedicated control electronics are required to operate the 3-phase AC electric motor in the 120-Volt high-voltage DC netting. The current converter is accommodated in the space formerly occupied by the starter. As the control electronics excite up as a result of electric currents measuring up to 150 amps, the system is equipped through its own, additional low-temperature cooling boundary line.

Mercedes-Benz engineers have accommodated the transformer in the right front deflect arch, where it facilitates the exchange of energy between the 120-Volt high-voltage network and the 12-Volt onboard netting - and also allows the option of emergency starting with leap over leads if the standard battery should lose its charge. To ensure a consistently noble level of electrical efficiency, the transformer is likewise cooled by a low-temperature circuit. The 12-Volt lead/acid battery is installed in the boot, and not sole stores the standard consumers but also the monitoring system for the high-voltage components with energy. Thanks to its interaction with the lithium-ion battery, it is considerably smaller in size and lighter than usual.

Tried-and-tested automatic transmission with a new configuration

Mercedes-Benz developers also adapted the well-proven 7G-TRONIC self-moving transmission to suit the hybrid drive, with newly programmed software for the transmission management system. A newly developed auxiliary oil pump ensures reliable lubrication of the transmittal even during phases whenever the internal consuming engine is switched off.

This complex system is managed by the modified high-performance weapon control unit. This incorporates extensive functions, and distinguishes between operating conditions equal as city traffic, rustic journeys, motorway driving or slow manoeuvring.

Hybrid status is shown in the instrument cluster

The driver is also able to monitor the rank of the hybrid drive system visually. The instrument cluster has a separate, centrally positioned, parade showing the energy flow during boost and recovery phases, as well as the battery charge status.

Seven-stage safety concept in addition to the Mercedes-Benz standard

As is usual at Mercedes-Benz, the development engineers gave safety aspects their very special attention. Know-how incorporated into the series-production car included long years of Daimler research experience through fuel-cell technology. The challenge lay in not only complying with all the worldwide and in-house legal crash test requirements, but also in ensuring the greatest possible safety for the electrical components. This safety system already applies in production, includes workshop personnel during servicing and maintenance, and also takes the emergency services into account when passengers need to be recovered following an accident.

Accordingly the cross technology of the Mercedes-Benz S400 BlueHYBRID is equipped with an extensive 7-stage safety concept.

1. In the highest platform all the wiring is colour-coded to eliminate confusion, and marked with close custody instructions. This prevents assembly errors in production, and makes the regular quality checks easier to transfer out.
2. The help stage comprises comprehensive contact protection for the entire system by means of generous insulation and newly developed, dedicated connectors.
3. As part of the third stage, the world’s first lithium-ion battery to have existence used in a series-production model has been given a unbroken package of carefully coordinated security measures. This innovative battery is accommodated in a high-strength steel housing, and also secured in place. Bedding the battery cells in a peculiar gel effectively dampens any jolts and knocks. There is also a blow-off vent with a rupture disc and a separate cooling circuit. An internal electronic controller continuously monitors the safety requirements and immediately signals any malfunctions.
4. The fourth stage of the safety concept includes separation of the battery terminals, individual safety-wiring for all high-voltage components and continuous monitoring by multiple interlock switches. This means that all high-voltage components are connected by any electric loop. In the event of a malfunction the high-voltage system is automatically switched off.
5. Active discharging of the high-voltage system as soon as the ignition is switched to “Off”, or in the event of a malfunction, is part of the fifth stage.
6. During an accident, the high-voltage system is completely switched off within fractions of a second (stage six).
7. As the seventh and highest stage, the hypothesis is continuously monitored for short circuits.

Thanks to its compact dimensions and modular design, the additional weight of the overall theory is only 75 kilograms - including the wide-reaching safety systems. The upper driving experience for which a Mercedes is known is therefore ensured by this trailblazing and real versatile technology, which have power to be used for practically entirely Mercedes-Benz model series. Moreover, the payload leavings unchanged at 595 kilograms.

The intelligent high-performance engine skill system responds exceedingly sensitively to different driving conditions, and optimally configures the drive system for the relevant application, ensuring that one as well as the other fuel consumption and emissions are kept to the lowest possible level.

At standstill the petrol engine is usually switched off, and accordingly consumes no fuel. The electric drive of the refrigerant compressor and steering servo cross-question allows unintermitted operation of the air conditioning and power steering. Comfort is in no way compromised, and is at the same high level as in all S-Class models.

Moving off and acceleratingaway gently remains a smooth and comfortable procedure. A driver who kicks the floor the accelerator for a agile start benefits from the boost law of derivation of the electric motor, which produces considerably more dynamic acceleration.

At constant speedsthe intelligent electronics recognise situations such as relaxed motorway stretches, and automatically adjust the load point of the internal combustion engine to bring to consummation a lower specific fuel consumption, thereby helping to save fuel and impoverish emissions.

When rolling to a stopthe recuperation function is activated as soon as the drive is interrupted in any way (foot-soldiers off the accelerator, engine braking). Once the carriage speed falls below 15 km/h, the petrol engine is automatically switched off.

If the driver brakes using the brushwood pedal, the electric motor initially begins to turn about the vehicle’s kinetic energy into electrical energy. In this case the electric motor acts as a generator, storing the kinetic energy as electrical energy in the lithium-ion battery. This continued experiment feels like a stronger engine braking effect to the driver. The conventional disc brakes at the wheels are not yet employed, saving wear and rend away. The disc brakes are only activated if the driver applies heavy pressure to the brake pedal, braking the car together with the engine brake and recuperation.

Once the driver selects “R” (reverse) in the 7G-TRONIC automatic transmittance when manoeuvring, this automatically activates the Manoeuvring way and prevents the start/stop function from switching off the engine at short, frequent intervals.

The advantages of the cross-bred drive system really get to into their confess in city traffic, with frequent stops at red traffic lights. Already switching off the petrol engine as the car frequently coasts to a stop significantly lowers the fuel consumption and emissions, while the long recuperation phases increase the battery charge. The relating to electricity motor ensures particularly comfortable and rapid restarting when the start/stop function is active.

On rural roadsthere are frequent changes between boost, constant speed and recuperation phases. Depending on the nature of the route, large quantities of recuperation energy are available to reduce fuel consumption and emissions. The more braking and acceleration phases there are, the better: ascending and downhill gradients, as well as winding, dynamic stretches, make as antidote to the largest savings.

The cross effect is inherently smaller quantity of moment on motorways, however thanks to specified modifications to the V6 petrol engine and the 7G-TRONIC automatic transmission, the driver is too able to achieve significant fuel savings and correspondingly lower emissions attached fast road stretches like these.

The Mercedes-Benz S400 BlueHYBRID is produced at the Sindelfingenplant, together by the other S-Class models. The petrol engine, 7G-TRONIC automatic transmission and electric motor are earliest put together to fashion a hybrid module, then delivered to the prolongation line as a unit. The emporium launch in western Europe is planned for June 2009; China is expected to follow in August 2009 and the USA in September 2009.