Internationaler Motorenkongress 2015

Bei BMW Motorrad besteht ein hoher Anspruch hinsichtlich Fahrdynamik, Verbrauch und Emissionierung, welcher sowohl von den Kunden, als auch im Rahmen der Konzernstrategie gefordert und vorangetrieben wird. Diese Ansprüche werden in Zukunft weiter wachsen. Um dem zu begegnen sind umfangreiche Maßnahmen erforderlich, um sowohl im Punkte der Nachhaltigkeit, als auch hinsichtlich der Fahrleistungen weiterhin die Spitzenposition zu belegen. Ausgehend von der EU4 Gesetzgebung und dem aktuellen Entwicklungsstand von Motorradantrieben bei BMW Motorrad wird der bereits begonnene Weg zur Verbesserung des innermotorischen Wirkungsgrades als auch der Schadstoffreduzierung dargestellt. Es werden technische Lösungen zur Verringerung des CO2-Ausstoßes bei gesteigerten Fahrleistungen aufgezeigt und deren Potentiale diskutiert.

Downsizing und Downspeeding von Ottomotoren sind etablierte Maßnahmen zur CO2- Reduzierung. Mit der Turboaufladung von Ottomotoren können großvolumige Motoren durch leistungsgleiche Motoren geringeren Hubraums ersetzt werden. Vorteile ergeben sich insbesondere durch niedrigere Reibleistungen, geringere Ladungswechselverluste aufgrund von Lastpunktverschiebungen und geringere Motorgewichte.

Die Weiterentwicklung von Verbrennungsmotoren ist in den letzten Jahren wieder stärker in den Fokus der Automobilindustrie gerückt, nachdem der Automobilmarkt für elektrifizierte Fahrzeuge sich nur sehr schleppend entwickelt. Die Steigerung der Wirkungsgrade für eine bessere Energieeffizienz ist jedoch nur in kleinen Schritten möglich. Dabei liegt neben der Optimierung von Verbrennung und Ladungswechsel ein Schwerpunkt auf der Reduzierung der Triebwerksreibung. An nahezu allen Komponenten des Verbrennungsmotors werden hierzu Detailoptimierungen durchgeführt. Die Betrachtung des Ölhaushaltes des kompletten Motors macht ebenfalls Sinn, insbesondere wenn es um Optimierungen der Komponenten wie die Ölpumpe, hydraulische Nockenwellenverstellungen, Ölspritzdüsen oder weitere wesentliche vom Motoröl versorgte Bauteile geht.

The modern Common-Rail PC Diesel engine is no more a European phenomena and the worldwide prognosis shows growth even in other parts of the world as India and China but also in US market.

Gasoline Direct Injection (GDI) concepts are the key technology of gasoline engine development to reduce CO₂ emissions while improving torque and power output [1]. However the drawback of GDI engines are increased particle number (PN) emissions compared to conventional Port Fuel Injection (PFI) engines [2] [3] [4]. For compression ignition engines (Diesel engines) a PN limit of 6E11 #/km was already introduced with the enforcement of Euro 5b (09/2011). The Euro 6b legislation also covers a PN limit for GDI engines effective from 09/2014. During the first three years of the introduction the manufacturer is permitted to apply a higher PN limit of 6E12 #/km. Finally a stricter limit of 6E11 #/km will become effective for all passenger cars and light duty trucks from 09/2017 (Euro 6c).

Downsizing in combination with turbocharging currently represents the main technology trend for meeting CO₂ emissions with gasoline engines. Besides the well-known advantages of downsizing the compression ratio has to be reduced in order to mitigate knock at higher engine loads along with increased turbocharging demand to compensate for the reduction in power. Another disadvantage occurs at part load with increasing boost pressure levels causing the part load efficiencies to deteriorate. The application of a variable compression ratio (VCR) system can help to mitigate these disadvantages.

The 2-stage VCR system with variable kinetic lengths entails variable powertrain components which can be used instead of the conventional components and thus only require minor modifications for existing engine architectures. The presented variable length connecting rod system has been continuously developed over the past years. The working principle and the system properties based on the current state of development will be shown in detail.

Various compression ratio ranges and considerations for actuation speed are being discussed in detail. A comparison of 2-stage versus fully variable compression ratio systems will be discussed and an outlook will be provided of how the presented 2-stage system and a fully VCR system can be utilized in current state-of the- art turbocharged direct-injected gasoline engines with the potential for significant CO₂ reduction.

Various fuel qualities in different markets worldwide, demand different layout of the compression ratio due to the changing knock behavior of the fuels. A VCR system has the potential to decrease fuel consumption and emissions dependent on the fuel quality. Advantages of VCR with multi fuel applications will be discussed.

Die Grundmotormechanik eines Verbrennungsmotors und deren optimierte Auslegung haben einen signifikanten Einfluss auf den Kraftstoffverbrauch und die Emissionen eines Motors. Neben Maßnahmen zur Reibungsreduzierung des Verbrennungsmotors durch Down-Sizing unter Verwendung von Motoren mit kleinerem Hubraum oder geringerer Zylinderzahl in Verbindung mit höherer spezifischer Leistung kommen nunmehr effiziente Strategien zur transienten Motorbetriebspunktverlagerung zum Einsatz. Eine Vielzahl der zuvor genannten Maßnahmen stellt besondere Anforderungen an die Systemintegration des Verbrennungsmotors. Besondere Bedeutung kommt dem Antriebsstrang zu, da oftmals Sekundärmaßnahmen zur verbesserten Schwingungsisolierung erforderlich werden. Im Rahmen dieser Publikation sollen einige dieser Maßnahmen anhand von technischen Beispielen vorgestellt werden und ihr Potential zur Kraftstoffverbrauchsminderung sowie mit Hinblick auf heutige und zukünftige Abgasemissionsanforderungen analysiert und evaluiert werden.

With the passage of Euro 6, and the recent U.S. introduction of new CO2 limits for heavy-duty trucks and buses, vehicle and engine manufacturers are facing a daunting challenge [1]. Compliance with these regulations requires significant financial investments in new technologies, all designed to increase fuel efficiency while decreasing emissions. But, to remain competitive, manufacturers cannot pass along these costs to fleet owners.

One solution to this problem is the opposed-piston engine. This engine, which has been optimized by Achates Power, was once widely used in a variety of applications including aviation, maritime and military vehicles. After overcoming the architecture’s historical challenges, the Achates Power opposed-piston engine now delivers a step-wise improvement in brake thermal efficiency over the most advanced conventional four-stroke engines. In addition, with the elimination of parts such as the cylinder head and valve train, it is also less complex and less costly to produce—making it even more appealing to manufacturers.

After a brief overview of the opposed-piston architecture’s inherent efficiency benefits, this technical paper features detailed performance and emissions results of a multi- cylinder Achates Power opposed-piston engine configured to meet current commercial truck requirements. These results demonstrate the engine’s ability to:

● Significantly improve fuel efficiency over the best diesel engines in the same class

● Comply with Euro 6/U.S. 2010 emissions standards

The discussion also includes an in-depth analysis of the opposed-piston, multicylinder test engine’s indicated thermal efficiency, friction and pumping losses as well as a road map for achieving 47.6 percent best-point brake thermal efficiency (BTE), which translates to 46.6 percent cycle-weighted BTE on medium duty engine.

Die Beimischung von Abgas zur Frischluft über die Abgasrückführung (AGR) dient beim Dieselmotor zur Reduzierung der Stickoxidemissionen (NOx). Zunächst ausgehend von einer reinen Steuerung der AGR, gefolgt von der Regelung des Luftmassenstroms ist heute die Regelung der AGR-Rate Stand der Technik. Dennoch weist die Regelung der AGR-Rate nur einen mittelbaren Zusammenhang mit der NOx- Entstehung auf: Bei gleicher AGR-Rate kann die Qualität des zurückgeführten Abgases erheblich variieren.

All current OBD legislation worldwide are based on either the European or the US legislation. Emission limits for combustion engines are the basis for the OBD regulations. New technologies, e.g. the electrification, place other components as air conditioning system, brake system, electric motor and HV-battery in the USA directly or indirectly into the OBD focus. The influence of the network topology raised because the number of the electric control units cross-linked under OBD criteria increased, especially as only a limited number of legally allowed diagnostics addresses are available.

This leads to network topologies, that have to be considered and evaluated critically under the premise of OBD-communication, particularly with specific timing requirements. Thus the OBD-requirements become a direct criterion for the network topology of electric control units and sensors/actuators in modern vehicles. New bus systems for sensors and actuators (e.g. LIN) must be considered also with respect to OBD requirements. Additionally to the increased number of the ECUs in the OBD-Network also functions and diagnostics of one ECU have direct influence on functions and diagnostics in other ECUs within the OBD network. Therefore signals, that are provided in the OBD network, must be evaluated under OBD requirements and must be flagged for OBD relevance in the bus system. Future OBD-communication concepts adapted to the increasing complexity must be agreed with the legislators and defined in standardization committees.

Die Verschärfung der Abgasgesetzgebung in Verbindung mit einer fortlaufenden CO₂-Limitierung bzw. weiteren Senkung des Kraftstoffverbrauchs im Nutzfahrzeugbereich wird zukünftig hocheffiziente SCR-Systeme erfordern. Um den Anforderungen gerecht zu werden, hat Bosch auf der AdBlue®-Einspritzseite einen modularen Spraybaukasten zur Anwendung in unterschiedlichen Applikationen entwickelt. Zusätzlich rückt auch das Thema AdBlue®-Gemischaufbereitung immer mehr in den Vordergrund. Hierzu wurde speziell für Nutzfahrzeug-Anwendungen eine mischerlose Drall- bzw. Swirl-Mischstrecke entwickelt mit Fokus auf geringem Gegendruck, sehr guter Vermischung des Abgases mit dem eingespritzten AdBlue® bei gleichzeitig hoher Robustheit gegenüber Ablagerungen. Gleichzeitig steigen auch die Anforderungen aus der On-Board-Diagnose insbesondere zur SCR-Katalysatorüberwachung; basierend auf einer neuen NOx-Sondengeneration mit schneller Taupunktendeerkennung und einem Steuergerätemodell, basierend auf passivem wie aktivem Monitoring des Katalysators, kann ein robustes und präzises Überwachungskonzept auch für sogenannte Hoch-NOx-Anwendungen in einem Bereich bis zu 8 g/kWh zur Verfügung gestellt werden. Damit lassen sich aus Sicht der Abgasnachbehandlung die aktuellen wie auch zukünftigen Anforderungen des Dieselantriebs im Hinblick auf Emissionsziele und Kraftstoffverbrauch sicher erfüllen.

Die Unterlagen wurden nicht zur Veröffentlichung freigegeben.

Wir bitten um Verständnis.

The development of commercial vehicle on-road applications, such as long haul trucks or busses, is driven by the optimization of the total cost of ownership (TCO) which relates the initial product cost with operating cost. Long haul truck applications have high annual mileage at high engine loads. Thus the operating costs dominate the total cost of ownership. Consequently lowest possible fuel consumption is one of the major drivers for long haul truck applications all over the world.

Engine manufacturers have been increasingly pressured by legislation and economics to reduce emissions and deliver improved fuel economy. A common strategy is to downsize and downspeed engines, and then compensate for the affected transient drivability through turbocharging, transmission and axle adjustments. This strategy can be highly effective, but there is a limit to how far it can be exploited before transient boost pressure, and hence transient torque, becomes too detrimental. Turbocharger manufacturers have mitigated this transient lack of exhaust enthalpy using technologies such as VTG (variable turbine geometry) and two-stage charging, especially with EGR-equipped air systems. Parallel to this issue but not separate is the scenario that sometimes the engine has more exhaust enthalpy than what is needed to power the turbocharger compressor. As a function of driver behaviour and the type of vehicle mission, the usage typically oscillates between these two conditions – too much energy or not enough.

These issues have been combated using technologies such as turbocompounding, waste heat recovery bottoming cycles and boost assist devices. Most have the restriction of only being able to deal with one of the two issues, either helping with transient boost or attempting to harvest and convert excess exhaust gas energy. An elegant solution to this problem would be to capitalize on the advances in power electronics and motor materials to electrify the turbocharger that is already packaged within the engine space. This electrified turbocharger would be able to harvest any excess enthalpy not currently needed to drive the compressor and at other times use that same stored energy to overcome transient boost lag.

A key development objective of the electrified turbo (eTurbo™) was to maximize power density. This resulted in a choice to select a permanent magnet electric machine that was placed within the bearing housing of the turbo. This design path was faced with considerable rotordynamic challenges due to placing a third high-mass object on the high speed turbocharger shaft. BorgWarner also chose to develop the eTurbo™ concurrently with the build of a mild-hybrid demonstration vehicle. This approach was taken not only to use the truck as a source of data but more importantly to experience and overcome system integration challenges and to gain integration practice.

The eTurbo™ equipped vehicle is minimally invaded since the turbocharger length grows by only 65mm. The power electronics controller is also quite small and adds just 12kg to vehicle mass. The battery pack is sized in accordance to the type of usage cycle and the final impact is the addition of either a mild hybrid addition to the powertrain or to implement electrified accessories. The end result is being able to use the generated power to offset fuel usage.

On an 11-liter long haul application, simulated fuel economy improvement of using an eTurbo™ on a ESC 13-mode steady-state test predicts maximum improvement of 5.6% and a 3.1% improvement at a key A50 road-cruise condition. Additional simulation of the turbo in a mildly hybridized 7-liter vehicle driving a city cycle showed fuel economy improvements up to 11% due to the combination of low levels of regenerative braking from the mild hybrid system and the power recovered by the eTurbo™.

For engine manufacturers looking to downsize and downspeed or even just improve drivability, the eTurbo™ is an attractive technology that does not require a fully hybridized vehicle or an overly expensive electrical infrastructure. Additionally, the eTurbo™ architecture is minimally invasive in comparison to the complexity of other waste heat recovery and boost-assist technologies.

Dieselmotoren von Nutzfahrzeugen, die die aktuelle Abgasnorm EU 5 oder EU 6 erfüllen, sind mit einem hochkomplexen Abgasnachbehandlungssystem ausgestattet. Dieses führt zu einer Erhöhung der Anschaffungskosten des Fahrzeuges sowie zu einer Verringerung der Zuladung. Ein weiterer wichtiger Aspekt bei Nutzfahrzeugen sind die Betriebskosten, welche gegenüber einem Personenkraftfahrzeug einen deutlich höheren Stellenwert besitzen.

The post Euro6 and post Tier4, respectively Tier5, emission legislation will not focus on further reduction of the emission limits, but will introduce more stringent test condition and on board diagnostic requirements. Life time stable emissions are already one key requirement for heavy engines and also for passenger car with the coming RDE legislation this will be one of the challenges leading to increased system complexity. On the other hand, the requirements listed in Figure 1 has led to an increased complexity of the diesel powertrain including the after treatment systems. Both passenger car and truck engines are facing the challenge to further reduce CO₂ emissions to meet future limits and avoid penalty cost. Thus system complexity reduction must be combined with CO₂ reduction.

High power density, small installation dimensions, reliability and flexibility in the installation situation and in fuels will be important and proven criteria for industrial engines in the future. In this context, an overall package adapted to the device application and the customer will be an important success factor.

Low operation costs at high levels of performance require optimum fuel consumption. Through the use of highly sophisticated technology and – corresponding to the increasing requirements – extensive optimization of the complete system, it is possible to realize outstanding combustion efficiency and fuel consumption with the current engine generation. Thanks to continuous improvement of these technologies, a further reduction in fuel consumption in the low single-digit percentage range also appears to be possible in the future. However, if larger steps in consumption optimization were to be achieved, attention would have to be focused on new approaches for optimizing the entire powertrain. In this case, the individual systems of the vehicle or the application (transmissions, hydraulics, control and diesel engine) are considered holistically and analyzed for optimization potential.

Hybridization, in other words the combination of the combustion engine with a second electric power source in the drive train, provides considerable consumption potential. Whereas a range of hybrid systems are nowadays a feature of the product range in the automotive industry, there are only a few prototypes and small series solutions in the off-road application sector.

Hydraulic actuators and drives are often in use in industrial machinery, and these can be extended with a start-stop function with the integration of hydraulic energy storage. Socalled ″mild hybrid″ systems with enhanced functionality, such as substitution of hydraulic with electric drives, provide interesting improvement potentials. In this context within a project funded by the Federal Ministry for Economic Affairs and Energy (BMWi) DEUTZ AG manufactured a mobile material handler with a hybrid drive as a demonstrator. The project, which was named ″GRID – Green Industrial Diesel″, was carried out in cooperation with TEREX FUCHS over the last few years. The hybrid system for this material handler consists of a mild hybrid drive with a diesel engine from the TCD 6.1 series, which was equipped with an electric motor and the necessary power electronics. High-performance electrical components are, for example, the electric rotary actuator, the cooling fan for hydraulic oil or coolant in hydraulic excavators, and – in the case of a material handler – the electric magnetic plate for the handling of metal parts. In addition, the hybrid system is fitted with an electrical energy store.

In addition to the overall objective of rational and efficient energy use, the specific challenge of system optimization is to keep the usual operating behavior of the machine for the operator at least the same despite any major system changes. The goal is of course to significantly increase the performance through a new level of freedom for the system topology. Another important requirement is to size the hybrid system as compact as possible, because there is often only limited space in industrial applications.

JCB Power Systems designs, develops and manufactures off-highway medium and heavy duty engines in the Power range 55kW – 225kW. These are used in construction, agricultural, industrial and power generation applications.

Currently, there is a world population of 7.2 billion people, with the tendency to rise. Every minute 150 people around the globe are born, which adds up to a total of 22.000 people a day and more than 80 million people a year. In the year 2050 an assumption indicated that we will be sharing our globe with approximately 9.6 billion humans. In average, this calculates to a necessary food production increase of 30% in order to cover the food consumption of the growing world population by 2050 [1].