Leading the way

The German based NEOMAN Bus Group – part of MAN Nutzfahrzeuge AG – is one of the leading companies involved with highly developed bus and coach technology worldwide. This fact is underlined by their latest bus and coach models as well as through new developments in the fields of safety, alternative drive systems and environmentally friendly engines. These developments include EEV Diesel engines without additional AdBlue, emission reduced hydrogen combustion engines for city buses and a new hybrid drive system that is already in development. In this article we will inform readers about all these developments first hand.

The new Cityliner

At the recent IAA Commercial Vehicles 2006 show, NEOPLAN (a NEOMAN Bus Group brand) presented the world premiere of the totally reinvented NEOPLAN Cityliner tour bus. Visually and technically the new Cityliner sets the standard in its category, thereby continuing the long NEOPLAN tradition of designing buses which are not just functional but also attractive. With this entirely redesigned generation of tour buses, NEOPLAN is writing a further chapter in the 35 year history of the Cityliner, which was fist presented to the public at the International Bus Week in Monaco in 1971 and has since sold more than 7,000 worldwide.

The fact that, in the pleasing design, the bus designers have not excessively stressed safety features – such as the rigid roll bar front and back – is a sign of the NEOPLAN team’s approach to technical safety: the highest standards of bus safety are de rigeur in NEOPLAN buses. To reinforce the overall bodywork of the bus, the builders of the new NEOPLAN Cityliner are using the tried and tested circular frame technology from the Starliner, in which the horizontal struts extend around the entire structure like in shipbuilding. At the intersections, which take particular strain between the undercarriage, floor and roof, the circular struts are manufactured using a special inner pipe technology without welded joints. It is additionally strengthened using stable joint plates. In addition, a new type of steel which has greater strength is used for the shell.

The latest driver aid systems and the distance control Tempomat ACC or the track monitoring system LGS are also available as options on the new NEOPLAN Cityliner. A further safety factor is the innovative light concept of the Cityliner, which is the first bus in its class to be fitted as standard with a bend light, which uses an enlarged beam of light to significantly improve vision on narrow bends and turns. This fascinating new coach shows what is possible today to give the passenger the most comfortable ride ever.

Exhaust gas recirculation

The NEOMAN Bus Group has clearly committed itself to exhaust gas recirculation (EGR) technology for the future. The next steps in the development of this innovative technology will soon follow. At the beginning of 2007 the small-volume engines of the MAN D08 Common Rail range will be available as an EEV version (Enhanced Environmentally-friendly Vehicle) for the city bus sector and at the end of 2007 the new MAN D20 Common Rail range with a 10.5 litre capacity will also be available. Unlike the Euro 4 engines these engines will be fitted with the electronically regulated CRTec particulate filter, which filters up to 99% of the particulates out of the exhaust gas. In addition further measures, such as a two-stage turbocharger, will be used to achieve the NOx values required in the Euro 5 and EEV standards.

The customer can not only trust fully in EGR today but in the future too. Several years ago MAN was the first European commercial vehicle manufacturer to opt for cooled exhaust gas recirculation (EGR) as a central feature of its engine strategy. At that time this solution already guaranteed the reliable fulfilment of the Euro 3 values without any increase in consumption, as has been confirmed by many customers. As a result a further developed version of the EGR technology is still central to our solution for meeting Euro 4 / Euro 5 or EEV standards without requiring any additives such as urea solution. The limits are complied with by means of an increased EGR share (for MAN D20 Common Rail) or EGR share with infinitely variable regulation (for MAN D 26 CR) and with an additional, electronically regulated particulate filter (CRTec, only for EEV engines). The newly developed D20 and D26 common rail engines are especially designed to meet the requirements of the future emission regulations and, in the bus sector, will also fulfil the Euro 5 standard for all power levels and applications without requiring any additives. The advantages of this solution are obvious: no additional operating agents or extensive infrastructure is needed; there is no effect on space and weight in the vehicle; and hardly any maintenance is required as the engines are robust and economical.

MAN’s technology is also well prepared for the Euro 6 exhaust gas standard, which is at present being planned and for the US standards EPA 2010. So MAN’s technology can be relied on to meet future requirements. In the view of many experts in this field no manufacturer will be able to comply with the future Euro 6 values without a reduction of the emissions within the engine such as the exhaust gas recirculation technology. Manufacturers will therefore be forced to develop such systems and components. For Euro 6 or EPA 2010 the exclusive use of SCR technology without EGR components will push the limits of this system. MAN, however, is well prepared to fulfil these new standards with its highly developed EGR system. As always MAN customers are thus already investing in modern exhaust gas technology which can be relied on in the future. MAN’s consistent strategy for the bus sector is the best and currently most cost effective way of running buses economically and environmentally acceptably.

Comfort and safety in coaches

Operators and passengers are always in good hands with coaches of the MAN and NEOPLAN brands. Beside a solid and perfected basic design, the latest engine technology and comfort and safety electronics are used. For example, for the first time NEOPLAN is presenting the new Comfort Drive Suspension (CDS) with electronically controlled shock absorbers to further increase the comfort and the safety of coaches. The ACC and LGS electronic safety systems can be ordered for the Starliner and Cityliner models or supplied as standard features (as for the NEOPLAN Starliner). These achievements have helped the new NEOPLAN Starliner win the ‘Coach of the Year’ title.

The electronic comfort drive system (CDS) has been especially modified for coaches. It basically functions in a similar way to the system for the trucks but it is designed to achieve increased comfort and increase safety. This is connected with the physical conditions of the vehicle concept – which does not react as strongly to rolling motion as a truck. In the coach it is also possible to select two comfort levels which are manually activated and influence the basic damping. In this way the vehicle can be adjusted to special loading situations or driving conditions.

Whether cornering with acceleration or cruising comfortably along the motorway with marked cross grooves – coach driving with CDS is always an experience. In particular pitching of the forebody is now hardly noticeable since the entire vehicle body is largely at one with itself. This makes not only the driver’s and courier’s work more relaxed but ensures that passengers enjoy an agreeable and restful journey.

The new comfort system will initially be offered as a standard feature in the NEOPLAN Starliner as the top product. Beside this system the vehicle also has a standard ESP and on request ACC and LGS are also available. This equipment amounts to a safety buffer which starts with the smooth control of the CDS and also incorporates the other safety systems as soon as the thresholds are approached. The system will also be available as an option in the new NEOPLAN Cityliner.

The most important element in terms of passive safety is the design of the shell. Both the NEOPLAN Starliner and the NEOPLAN Cityliner have spars running right round the body and patented reinforcements for the side wall attachment – designed to achieve a further improvement in the rigidity of the body. The electronically controlled brake system (EBS 2) with disk brakes on all wheels and the integrated brake assistant, which recognises an emergency braking manoeuvre right from the start and immediately builds up the largest possible brake pressure, is a further ingredient in an all-round safety package for MAN and NEOPLAN coaches.

Maximum speed control (MSC) prevents the bus from exceeding the permissible top speed limit even downhill. In addition, from autumn this year the safety-promoting driver assistance systems, e.g. Adaptive Cruise Control (ACC) or Lane Guard System (LGS) can be supplied and used in series vehicles. Both systems are offered as standard in the NEOPLAN Starliner and are available at an extra charge in the Cityliner. In the course of 2007 the systems will be offered also as options for the standard coaches MAN Lion’s Coach and NEOPLAN Tourliner. For the first time a NEOPLAN coach features bi-xenon headlights (standard for NEOPLAN Starliner and as an option for the NEOPLAN Cityliner) and a new light for cornering, which thanks to an additional beam considerably improves visibility on tight bends. The headlight has already been prepared for integration of further functions currently under development. The system is used both in the NEOPLAN Starliner and in the new Cityliner.

Hybrid drive technology

Within the context of a research project MAN Nutzfahrzeuge has further improved the ultracap bus. It has already been tested in scheduled-service operation in Nuremberg since 2001 by means of a variety of optimisation measures. Essential features of these measures are the use of a newly developed ultracap storage system, the requirement-oriented operation of secondary units and optimised energy management implementing an automatic stop-and-start system.

The hybrid drive technology is based on the diesel-electric principle. A series-produced diesel engine drives a high-performance generator supplying the power for two electric drive motors. The high-performance generator and the drive motors, which drive the rear axle via a summing gearbox, are connected with each other via a power inverter. In addition, the energy accumulator mounted on the roof of the bus is connected with the electric drive system via another high-performance electronic system. The driving power for the drive motors can be provided either by the diesel engine via the generator or by the energy accumulator direct. When the bus moves off, driving power is first taken from the energy accumulator. This offers the advantage that the bus can leave the bus stop area while being driven purely electrically and that the diesel engine only comes into play afterwards. As a result, moving-off noises and emissions are reduced in the bus stop area quite significantly.

Ultracap storage technology

An optimised ultracap storage system newly developed by MAN is employed as braking energy accumulator. For this purpose high-performance capacitors, so-called ultracaps, incorporating state-of-the-art technology are used. A comparable energy regeneration and storage system is also used in the further-developed MAN fuel-cell bus which was launched in 2004. Within the context of a project supported by the Bavarian State Ministry of Transport this bus is being tested in scheduled-service operation near Munich airport until the end of 2006.

Ultracaps fundamentally differ from other energy accumulators such as batteries or flywheel storage systems by their particularly high power density, high power take-up capacity, reliability, high efficiency, the absence of moving parts and their maintenance-freeness. The storage capacity is designed so that the energy from one braking operation from 60km/h can be stored complete. The newly developed ultracap storage system distinguishes itself mainly by a drastic reduction in storage losses as well as by a marked extension of its service life up to that of the vehicle itself thanks to improved cooling.

The IDEAS project

From today’s point of view, the diesel drive, particularly in commercial vehicles, will remain the main propulsion system in the medium run. Consequently, from an environmental perspective the efficiency and environmental compatibility of this drive system is to be further increased. At MAN this need is reflected in the new Common Rail D20 engine. With its more compact dimensions the unit puts out considerably more power than its predecessor; since 2006 the engine has been available for buses and coaches too. In addition, MAN took part in several research projects aimed at achieving further cuts in fuel consumption and in exhaust-gas and noise emissions in commercial vehicles for use in urban areas – particularly city buses – without impairing their performance.

MAN Nutzfahrzeuge AG is continuing its systematic development of hybrid drive systems with diesel engines for the city bus sector in cooperation with its supplier Siemens. At the beginning of 2007 two vehicles based on the MAN Lion’s City are planned for completion. The entire investment volume for the IDEAS project (IDEAS stands for “innovative diesel-electric hybrid drive for city buses”) is about €4 million; €1.4 million of this comes from subsidies from the Federal Ministry for Education and Research (BMBF). The project is part of the ministry’s research programme for mobility and transport planned from 2000 to 2005.

The research projects to date have revealed a considerable potential for fuel saving with hybrid-drive systems for city buses, in which the familiar diesel-electric drive is combined with a suitable energy accumulator. In MAN’s view two drive systems are effective and forward-looking. The first variant, which is designed to achieve minimum fuel consumption, is a hybrid system with an ultracap storage system. This system makes it possible to leave bus stops by means of electricity and thus without any emissions (noise, exhaust gas). This has the additional advantage that it reduces the annoyance caused to passengers and to the people who live near to the bus stop.

The emphasis of the second version is on the reduction of emissions. This design consists of a combination with a high-performance battery system which, compared with the ultracap storage system, provides a considerably larger energy content. At the same time this permits emission-free, pure electric operation in core zones. Owing to the measures necessary to comply with the federal emission protection regulation this design could become more interesting in future.

The vehicles built within the framework of the project are to be used in real service trials of a year each in local public transport at VAG in Nuremberg. Beside the trials, another important factor for the introduction of these alternative drive systems is the analysis of the effects of using these systems on bus operators. Using a bus operator’s the entire service network as an example, possible changes in investment costs, running costs, the outlay for maintenance and an optimised fleet structure can all to be taken into account.

MAN Nutzfahrzeuge AG is working on future-oriented technologies for use in local public transport and in the lightweight distribution sector. The objective is to achieve significant cuts in consumption and in emissions. The potential of the hybrid technology appears to be very promising. However, introduction in the market of such systems is conceivable only in the medium run.

All these technologies and trends in the bus and coach sector help transport enterprises as well as the passengers themselves to enjoy the best of modern transport ideas. NEOMAN is always at the head of the development in all of these fields of expertise. We will continue to do research in these areas for the benefit of passengers and public transport.