Promote and demand
The Rhein-Ruhr transport association (VRR), of which WSW mobil GmbH is also a member, launched a promotional programme for buses with hybrid technology in 2009. Today approximately 70 hybrid buses belonging to VRR transport companies have been subsidised with the help of the programme for "Innovative projects for the improvement of local public transport". The objective is to pool the findings and experience gained with regard to the new technology as part of a research programme and put them at the disposal of other transport companies and vehicle manufacturers. Ulrich Piotrowski is responsible for the market launch of hybrid and electric buses at Mercedes‑Benz. He believes that: "Wuppertal is just perfect for using the Citaro G BlueTec Hybrid. The demanding topography provides sufficient opportunity for energy recuperation via the brakes, but, if necessary, can also clearly demonstrate deficits thanks to the challenging routes. The experience gained during daily operations is invaluable to the further development of vehicles."
Mercedes-Benz Citaro G BlueTec Hybrid
When topographical conditions are ideal, the Citaro G BlueTec Hybrid can drive up to 10 kilometres using exclusively electric power without the help of the diesel engine. Four electric wheel hub motors which draw their power from lithium ion batteries provide the drive. Electric current is generated when the brakes are applied and, if required, can also be obtained via a generator which is driven by a small diesel engine. Experts speak of a serial hybrid in this context.
Needs-based equipment
The technically sophisticated diesel-electric hybrid concept has been realised in the well-established articulated version of the successful Mercedes-Benz Citaro urban bus family. The light blue vehicle hardly differs from the rest of the WSW Citaro fleet. The bright and friendly interior is characterised by large windows. The traffic red grab rails are a contrast to the blue seat covers. A video surveillance system with five cameras improves safety and avoids damage through vandalism. The climate control in the passenger compartment and at the driver's workplace can be regulated independently of one another via the overhead air-conditioning system. The air-conditioning concept, just like the fire alarm system and the automatic fire extinguishing system in the engine compartment, is standard WSW equipment.
Two 48.26 cm TFT monitors in the front and rear sections display the names of bus stops. When connected to the IBIS on-board computer, information regarding route progress and the name of the next bus stop are displayed. The IBIS is not only responsible for the control of the passenger information systems, but also for traffic signal preemption in Wuppertal. The control centre can directly transmit acoustic and visual information to one or all of the vehicles on the service route. The exact position of the vehicle is determined, evaluated and transmitted to the passenger information boards located at the bus stops using GPS. Passengers at the bus stops are thus informed in real time about exact arrival and departure times.
HighTec in urban buses
Four electric motors influence the driving characteristics of the Citaro. They accelerate the 18 meter long bus quickly and almost silently. As no transmission is used, passengers notice no jerking typical of gear changes. The drive output of the wheel hub motors is 320 kW, supplied as required by the battery and the diesel engine driven generator. These electric motors are also used for braking the vehicle. They then function like generators and convert the brake energy into electric current for the battery. If the battery indicates that it requires more power, the diesel engine automatically starts in order to generate additional energy. In comparison to a bus that runs on diesel only, the combustion engine is only half the size, weighs only 450 kg instead of 1000 kg and its engine capacity is 4.8 litres as opposed to 12 litres. At 160 kW, its output is about one third lower.
The energy storage unit used in the Mercedes‑Benz Citaro G BlueTec Hybrid is a lithium ion battery. The battery system supplies a maximum of 240 kW and, weighing less than 350 kg, is comparably light. Compared to conventional battery systems, batteries with ion technology impress with a higher energy density in conjunction with a greater storage capacity and lower weight.
WSW mobil GmbH
At present the 100 percent subsidiary of the Wuppertal Stadtwerke GmbH employs around 740 employees. In 2010, 89.6 million passengers used the WSW mobil GmbH services. The bus fleet comprises approximately 300 regular service buses. Together the 65 service routes are 633.7 km long, whereby the service stretches from Wuppertal and Solingen via Remscheid to as far away as parts of the Ennepe-Ruhr district.
Credits: Daimler AG
Copyright © 2012, Mercedes-Benz-Blog. All rights reserved.
Learn more about Mercedes-Benz' dedicated winter customer care program by following the next links:
1. Winter time with Mercedes-Benz: Heading to the slopes (I)
2. Winter time with Mercedes-Benz: Heading to the slopes (II)
3. Winter time with Mercedes-Benz: Heading to the slopes (III)
4. Winter time with Mercedes-Benz: Heading to the slopes (IV)
5. Winter time with Mercedes-Benz: Heading to the slopes (V)
6. Permanent adhesive power: the 4MATIC all-wheel drive system from Mercedes-Benz (I)
7. Permanent adhesive power: the 4MATIC all-wheel drive system from Mercedes-Benz (II)
8. Permanent adhesive power: the 4MATIC all-wheel drive system from Mercedes-Benz (III)
9. Permanent adhesive power: the 4MATIC all-wheel drive system from Mercedes-Benz (IV)
Copyright © 2011, Mercedes-Benz-Blog. All rights reserved.
Superb THERMOTRONIC automatic climate control: Perfect climate aboard M-Class and E-Class
Carefully balanced control of the interior climate is especially important in the winter. This is why Mercedes-Benz offers the THERMOTRONIC luxury automatic climate control system for the E-Class and M-Class. Apart from regulating the climate separately for the driver, front passenger and passengers in the rear, it allows individual pre-settings to be programmed too.
This system furthermore includes a pollutant sensor which automatically switches to air recirculation mode if it detects any sudden increase in the carbon monoxide or nitrogen oxide levels in the outside air – when driving through a tunnel, for instance. Another highlight of the THERMOTRONIC system is the residual heat function: pressing the “Rest” button heats or ventilates the passenger compartment for around 30 minutes when the engine is switched off.
THERMOTRONIC heats up the passenger compartment efficiently, even after a cold start on winter mornings. This is thanks to a heating output of eleven kilowatts, equivalent to the capacity of the central heating system in a modern family home. On the diesel models, a heat exchanger with six integral PTC heating elements (PTC = Positive Temperature Coefficient) is also activated when the outside temperature falls below a certain level in order to boost the effect of the main heat exchanger with an electrical output of around 1200 watts. The assistance from the PTC heater is necessary due to the high thermal efficiency of today’s CDI engines, which is precisely what makes them so economical and means that they dissipate considerably less heat to the coolant under partial load conditions than conventional engines. The E-Class and M-Class are equipped as standard with THERMATIC, a two-zone automatic climate control system.
To make long journeys or lengthy winter outings in the M-Class even more enjoyable, the centre console holds a little surprise in store: the tempered cup holders include a Peltier element that is capable of keeping drinks hot or chilled in a temperature range of 8° to 55° Celsius at the push of a button. So, a “take-away” coffee can be kept hot on the morning drive to the slopes, for example. Alternatively, with the cooling function activated, the thermal cup holders are able to stop chocolate bars from melting if a very high interior temperature has been set.
Source: Daimler AG
Copyright © 2011, Mercedes-Benz-Blog. All rights reserved.
E-Class 4MATIC: stability pact for the winter: Gripping drive system for Saloon and Estate
The 4MATIC powertrain in the E-Class is one of the best-performing permanent all-wheel drive systems on the market. The basic design concept, with the engine installed longitudinally and the integral transmission and transfer case unit, produces a compact, lightweight arrangement that minimises frictional losses, heralding a number of benefits compared to other passenger car systems with a transverse power unit and selectable 4x4. As with the 4MATIC system’s set-up on a dry or wet road, handling stability and, therefore, active safety are paramount at all times when wintry conditions prevail, too.
The mechanical principle of the 4MATIC system, featuring a 45:55 torque split between the front and rear axles and a multi-disc limited-slip centre differential with a basic locking torque of 50 Nm, offers all the right ingredients. This basic design enables high levels of traction, as the dynamic shift in axle load toward the rear axle that occurs during acceleration is harnessed to deliver more drive torque to the rear wheels. However, the multi-disc differential lock is also able to shift the drive torque between the front and rear axles, varying the split between 30:70 and 70:30 as the road conditions dictate. Consequently, intervention by the ESP®, 4ETS or ASR electronic control systems can be delayed for as long as possible and the bulk of the drive torque converted into tractive power, even on slippery roads. All control system interventions go virtually unnoticed, yet drivers still know straight away if they are driving near the limit, as a yellow warning symbol will flash in the instrument cluster. This serves as a clear prompt to adapt the driving style to the road conditions.
The drive mechanism’s permanently engaged design offers key advantages over other systems that first need to diagnose a lack of grip before activating the 4x4 drive. The 4MATIC on the E-Class will have already made use of this valuable time to start transmitting drive torque via the wheels to the road. When pulling away in wintry conditions, the E-Class 4MATIC models are designed to develop maximum traction. To this end, certain road conditions are automatically detected and the interventions of the 4ETS electronic traction control system adjusted so as to achieve the greatest possible acceleration while minimising wheel slip, thereby ensuring optimum handling stability.
New petrol engines and an optimised powertrain make the 2011 Mercedes-Benz
E-Class the standard for efficiency in its segment. All of the petrol and diesel engines in the E-Class range now employ direct injection technology, with combined fuel consumptions of 6.8 - 7.0 litres and 8.9 litres per 100 km respectively for the new BlueDIRECT V6 and V8 units. The reduction in fuel consumption of up to 20 percent is also due to the standard ECO start/stop function and the improved 7G-TRONIC PLUS 7-speed automatic transmission, which is now also available for the four-cylinder model variants.
E 250 CDI BlueEFFICIENCY 4MATIC: First ever all-wheel drive E-Class with a four-cylinder diesel engine
The ECO start/stop function and 7G-TRONIC PLUS ensure a particularly high level of energy efficiency in the E 250 CDI BlueEFFICIENCY 4MATIC. The first E-Class with 4MATIC and a four-cylinder diesel engine has an output of 150 kW (204 hp) and stands out for its smooth drive characteristics coupled with impressive performance: it completes the sprint from 0 to 100 km/h in 7.9 seconds and reaches a top speed of 238 km/h. In the process, the engine burns just 5.6 l/100 km on the NEDC driving cycle, making the E 250 CDI BlueEFFICIENCY 4MATIC the most efficient all-wheel drive diesel model in its power category in the executive class.
Source: Daimler AG
Copyright © 2011, Mercedes-Benz-Blog. All rights reserved.
New chassis developments and innovative dynamic handling control systems: Relishing the winter with the M-Class
Outstanding safety and well-balanced ride comfort combined with impressive driving dynamics on dry, wet as well as wintry roads, plus superlative skills off the beaten track are some of the key strengths of the third-generation M-Class with permanent all-wheel drive. The premium SUV also makes its mark with new chassis developments and innovative dynamic handling control systems designed to increase both driving pleasure and active safety in winter.
The optional ON&OFFROAD package for the new M-Class uses six different driving modes to optimise driving dynamics and handling safety by providing the optimum drive control needed to cope with the wide spectrum of operating conditions encountered both on and off the road. Drivers have the choice of an automatic mode, two specially programmed off-road modes as well as three on-road modes – “Winter”, “Sport” and “Towing”.
The specific driving modes for all-wheel drive resolve a conflict of objectives that has previously hampered further development of 4MATIC and the 4ETS electronic traction system as well as ESP® and acceleration skid control (ASR). To take an example: on off-road tracks or snow-covered roads, it is important that the control systems respond very gently due to the low friction coefficients, but this makes a sporty set-up virtually impossible. Conversely, a sporty basic setup impairs performance abilities in off-road terrain and snow. In the past, excellent compromises were always found which worked brilliantly under all conditions. The new ON&OFFROAD package with its specific driving modes, however, enables driving dynamics and handling safety to be optimised almost as far as is physically possible under all operating conditions by maximising networking between the individual control systems.
In terms of “hardware”, the ON&OFFROAD package comprises an underguard, a two-stage transfer case with low-range ratio, an inter-axle differential lock and enhanced AIRMATIC functionality that allows a maximum ground clearance of 285 millimetres and a fording depth of 600 millimetres.
Winter driving mode: more fun, more safety
The driving mode is chosen using a rotary control on the centre console. To ensure the selected driving mode – in this case “Winter” – is clearly indicated, a special snowflake graphic appears in the instrument cluster, while the COMAND screen shows the M-Class in a wintry, snow-covered landscape.
The ON&OFFROAD package’s winter driving mode optimises handling on roads affected by snow, ice or freezing rain and when using snow chains, and offers drivers added safety with its well-defined, predictable reactions. The extensive fine-tuning work carried out focused on further increasing longitudinal traction, at the same time as improving lateral dynamics and handling safety. The development team was able to implement these specifications to impressive effect using targeted control mechanisms in the drivetrain:
- When pulling away with or without the steering turned, the inter-axle lock in the centre differential is triggered earlier in order to increase traction and reduce understeer when accelerating briskly. In parallel to this, the 7G-TRONIC PLUS switches to the “gentler” ECO mode and automatically engages 2nd gear when pulling away to avoid high wheel slip. Finally, a flatter response curve gives the driver more sensitive control over the accelerator pedal.
- Maintaining a locking torque that has been set in the centre differential for longer improves handling stability and helps the driver by making the self-steering characteristics more definite.
- Higher ASR slip thresholds when driving in a straight line result in high traction levels as well as safe operation with snow chains with outstanding tractive power.
- ASR slip thresholds lowered when cornering in order to ensure stable handling characteristics at all times as far as is physically possible.
ACTIVE CURVE SYSTEM for safe fun in the snow at its very best
When the ON&OFFROAD package is combined with the ACTIVE CURVE SYSTEM (ACS), a specially programmed winter set-up guarantees dynamic driving pleasure while giving the driver excellent control over the vehicle for a high degree of handling safety. ACS uses active anti-roll bars at the front and rear axles to compensate for the roll angle of the body through bends, increasing agility and driving pleasure in the process. At the same time, the system is capable of giving the M-Class greater traction, especially in wintry road conditions with low grip levels.
The ACTIVE CURVE SYSTEM “Snow mode” features two control strategies. Firstly, many of the parameters needed for driving on wintry roads are already incorporated into the basic functions, i.e. when the ON&OFFROAD package’s Automatic driving mode is activated. This means that the system’s reactions to the driver’s steering inputs will be less dynamic on slippery surfaces. External influencing factors, such as fluctuating friction coefficients on roads that are partially covered in ice or snow, are balanced out faster though. Thanks to this control strategy, the M-Class becomes far more docile, even if the vehicle switches between moderate oversteer and understeer.
Secondly, the system control for the winter driving mode includes a special control algorithm. In just the same way as the shaped skis thrill alpine skiers by closely following the desired line even through turns with a tight radius, the M-Class handles in tight bends in this mode. This control strategy produces increased traction on snow-covered road surfaces by dynamic displacement of the wheel loads. If the driver turns into a tighter bend while travelling at a constant speed or accelerating, the wheel load and, as a result, the traction will be increased at the front wheel on the outside of the bend. Doing so minimises the understeer that is otherwise typical in this driving situation. If the driver then reduces the steering angle when exiting from the bend while travelling at a constant speed or accelerating, the load at the rear wheel on the outside of the bend will be raised instead. This has the effect of increasing lateral support at the rear axle, so that the vehicle’s handling is stabilised in the same way as when entering the bend. This time though, it is the tendency to oversteer that is countered.
M-Class sets benchmarks in the world of SUVs
The third generation of the Mercedes-Benz M-Class excels above all with its outstandingly efficient use of energy. On average, the fleet consumes 25 percent less fuel than the predecessor models. The ML 250 BlueTEC 4MATIC is the fuel efficiency champion, consuming just 6.0 l per 100 km on the NEDC driving cycle (158 g CO2/km) and capable of covering up to 1500 kilometres on a single tank of fuel. Other key strengths of the premium SUV with permanent all-wheel drive include outstanding safety and well-balanced ride comfort combined with impressive driving dynamics both on the road and off the beaten track. A distinctive body design and a versatile interior that is highly conducive to its occupants' wellbeing further enhance the M-Class driving experience.
Source: Daimler AG
Copyright © 2011, Mercedes-Benz-Blog. All rights reserved.
Mercedes-Benz 4MATIC: the pinnacle of permanent all-wheel drive - The great 4x4 for the winter
All-wheel drive is still the top choice for enhanced mobility when road conditions turn wintry. 4MATIC, the permanent, electronically controlled 4x4 system from Mercedes-Benz, promises particularly impressive progress, as it boasts truly formidable performance capabilities on snow-covered and icy roads. High traction reserves, excellent directional stability, peerless safety and exceptional comfort levels are all among the drive concept’s highly persuasive benefits.
Not all 4MATIC systems are the same, though – Mercedes-Benz tailors the system to suit the operating profile. So, the new M-Class is equipped with a 4MATIC variant that delivers supremely assured handling on the road combined with top-class off-road technology, while the E-Class employs a system which is geared towards optimum on-road performance. One basic rule applies to all 4MATIC models in the winter, namely that the system can only work as effectively as the connection between the vehicle and the ground allows. In other words, suitable winter tyres are still indispensable.
Outstanding safety and well-balanced ride comfort combined with impressive driving dynamics on dry, wet or wintry roads are some of the key strengths of the third-generation M-Class with permanent all-wheel drive. The premium SUV also makes its mark with superlative skills off the beaten track, thanks to new chassis developments and innovative dynamic handling control systems designed to increase both driving pleasure and active safety.
The optional ON&OFFROAD package for the new M-Class uses six different driving modes to optimise driving dynamics and handling safety by providing the optimum drive control needed to cope with the wide spectrum of operating conditions encountered both on and off the road. Drivers have the choice of an automatic mode, two specially programmed off-road modes as well as three on-road modes – “Winter”, “Sport” and “Towing”.
The ON&OFFROAD package’s winter driving mode improves handling characteristics on roads affected by snow, ice or freezing rain and when using snow chains, and offers added safety. The extensive fine-tuning work carried out focused on further increasing longitudinal traction, at the same time as improving lateral dynamics and handling safety. The development team was able to implement these specifications to impressive effect using special control mechanisms in the drivetrain.
When the ON&OFFROAD package is combined with another optional feature, the ACTIVE CURVE SYSTEM (ACS), a specially programmed winter set-up offers dynamic driving pleasure while giving the driver excellent control over the vehicle for a high degree of handling safety. At the same time, the system is capable of giving the M-Class greater traction, especially in wintry road conditions with low grip levels. What’s more, this set-up boasts even greater directional stability in tighter corners produced by a special control algorithm that is programmed into the system.
E-Class 4MATIC: stable handling on snow and ice
As with the system’s set-up on a dry or wet road, handling stability and, therefore, active safety are paramount at all times when wintry conditions prevail too in the E-Class models with 4MATIC. The mechanical principle of the 4MATIC system, featuring a 45:55 torque split between the front and rear axles and a multi-disc limited-slip centre differential with a basic locking torque of 50 Nm, offers all the right ingredients for this.
This basic design enables high levels of traction, as the dynamic shift in axle load toward the rear axle that occurs during acceleration is harnessed to deliver more drive torque to the rear wheels. However, the multi-disc differential lock is also able to shift the drive torque between the front and rear axles, varying the split between 30:70 and 70:30 as the road conditions dictate. Consequently, intervention by the ESP®, 4ETS or ASR electronic control systems can be delayed for as long as possible and the bulk of the drive torque converted into tractive power, even on slippery roads. All control system interventions go virtually unnoticed, yet drivers still know straight away if they are driving near the limit, as a yellow warning symbol will flash in the instrument cluster. This serves as a clear prompt to adapt the driving style to the road conditions.
For the first time ever, an E-Class with 4MATIC and a four-cylinder diesel engine is being made available in the shape of the E 250 CDI 4MATIC BlueEFFICIENCY. This model has an output of 150 kW (204 hp) and stands out for its smooth drive coupled with remarkable performance. In the process, it burns just 5.6 l/100 km on the NEDC cycle, making it the most efficient all-wheel drive diesel car in its class.
M-Class and E-Class: perfect climate with THERMOTRONIC
Mercedes-Benz offers the THERMOTRONIC luxury automatic climate control system for both the E-Class and M-Class. Apart from regulating the climate separately for the driver, front passenger and passengers in the rear, it allows further individual pre-settings to be programmed too. Another feature of the THERMOTRONIC system really comes into its own in the winter months: the residual heat function is activated by pressing the “Rest” button, and heats the interior for around 30 minutes when the engine is switched off.
THERMOTRONIC heats up the passenger compartment extremely efficiently at low outside temperatures, even after a cold start in the morning. This is thanks
to a heating output of eleven kilowatts, equivalent to the capacity of the central heating system in a modern family home. On the diesel models, a heat exchanger with six integral PTC heating elements (PTC = Positive Temperature Coefficient) is also activated when the outside temperature falls below a certain level in order to boost the effect of the main heat exchanger with an electrical output of around 1200 watts. To make long journeys or lengthy winter outings in the M-Class even more enjoyable, the centre console holds a little surprise in store: the tempered cup holders include a Peltier element that is capable of keeping drinks hot or chilled in a temperature range of 8° to 55° Celsius at the push of a button.
Mercedes offers 4MATIC in 49 passenger car models
The Mercedes-Benz all-wheel drive line-up currently encompasses 49 passenger car models across ten model series for the German market, and offers an impressively wide choice. Besides the E-Class and the C-Class, which both come in saloon and estate variants, the 4MATIC portfolio is enriched by models from the S-Class,CL luxury coupé, CLS four-door coupé and R-Class touring SUV‑ranges too. These are joined by the third-generation M-Class that was brought out this year, the compact GLK and the GL full-size SUV. Still going strong after over 30 years in production, the G-Class truly comes into its own off the beaten track and continues to rank as one of the best cross-country vehicles in the world.
Source: Daimler AG
Copyright © 2011, Mercedes-Benz-Blog. All rights reserved.
