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Automotive changes and challenges for the Environment’s sake.

Issued at 2010-12-16



Downsizing, down-speeding, hybrid and electric drives are some of the technologies to reduce CO2 emissions in the automotive industry. It is interesting to note what impact this will have in terms of opportunities and challenges for the casting industry. Here we look at the possible effects for three main product segments - chassis, drive, and bodywork.

 Outlook

In accordance with studies, 30% of the CO2 emissions of vehicles are generated in the production phase and 70% in the period of usage. Thus, the entire process chain, including the energy needed for manufacturing the components, will have to be incorporated more strongly in the equation to further reduce CO2 emissions.

Materials and processes with lower levels of CO2 emissions should prevail and development activities in this area remain paramount. Circle closure, reduction of material and energy use, and avoidance of toxicities are essential target variables. Deriving an efficient CO2 reduction strategy requires the environmental effects of the entire product lifecycle to be evaluated.

The use of aluminium for the purposes of weight reduction can be taken as an example. The energy required to manufacture an engine block consisting of primary aluminium is three times as high as for a housing consisting of cast iron. When using secondary aluminium the balance will be improved immediately and one requires significantly less driven kilometres to compensate the higher energy required during the manufacturing procedure. The CO2 balance can be influenced essentially not only in the field of material selection, but also on the basis of the casting process itself. For example, the thermal energy generated in the cupola melting furnace can be used further within the attempts to reduce CO2 emissions. An example is the Maggi factory in Singen which utilises the hot gases of the adjacent casting factory of Georg Fischer in Singen to generate saturated vapour for their production system. This way, the environment is relieved of more than 11,000 tons of CO2 emissions per year(1).

 Targets for the automotive industry

Increasing the efficiency in each vehicle segment is the target, regardless of whether the vehicle concerned is a compact vehicle, family van, or SUV. Within the European Union, the member states have agreed upon uniform, long-term specifications for the reduction of CO2 in terms of road traffic. Starting in 2012, the CO2 emissions of new vehicles within the EU have to be reduced gradually, from approx 160g/km to 130g/km in the year 2012. A fleet value will be determined for each major manufacturer, at which the aforementioned depends on the product portfolio, i.e. the average weight of the fleet of the manufacturers.

 Development tendencies to reach the CO2 fleet consumption targets

The following three fields may provide a decisive contribution to reaching the targets:

  • lightweight design
  • optimisation of the combustion engines
  • alternative drive concepts

 It is obvious: the lower the weight that has to be moved, the lower the force required to move the same and the less fuel is consumed - an approach applicable to all vehicle groups. By reducing the vehicle weight by approx 100kg the consumption can be reduced by approx 0.5L/100km, corresponding to a CO2 reduction of 3.5g/km. Along with lightweight design materials such as aluminium, magnesium, or plastic materials, the structures are increasingly weight-optimised as regards the required function. Bionic design approaches and the use of different pairs of materials provide a contribution to this. The same results in the energy and material demand being reduced, as well as in the economic efficiency of the systems being improved. The optimisation of the combustion motors particularly aims at increasing the efficiency and downsizing. Modifications regarding the development and integration of new drive technologies are possible. Fuel cell, hybrid, or electric drives are only a few examples of possible drive technologies. There is no uniform technology tendency yet, the opportunities in this field are numerous.

 Effects on system groups within the vehicle

If you classify a vehicle into the three main groups: chassis, body-work, and drive, the targets of CO2 reduction have different effects and influences. Today, the overall weight of an average passenger vehicle is approximately distributed as follows: 40% body-work, 25% chassis, 20% features, including electronics, and 15% drive. Depending on the vehicle types, hybrid and electric drives have effects on body-work and chassis to a limited extent only. Thus, here the focus is on lightweight design. On the one hand, the additional weight on the basis of additional batteries and electric motors has to be compensated in case of hybrid vehicles. On the other hand, a lower vehicle weight also provides a contribution to a reduction of CO2. Thus, together with the customer in each case, components for drive, body-work, and chassis for passenger vehicles and commercial vehicles are the focus of R&D in the field of lightweight design at Georg Fischer Automotive. The technologists achieve reductions in vehicle weight by using light and high-performance materials(2). This is also achieved by using installation spaces and by loading components in an ideal manner. To protect human beings and the environment, high requirements for operational safety are implemented at the same time. A front knuckle in iron casting can be used as an example for the aforementioned, at which the same has been optimised with bionic methods and materials with higher strength levels.

 Power train combustion motor

In the next 20 years a large contribution to the concept of CO2 reduction will be achieved by increasing the efficiency of conventional combustion motors and hybrid drives. Objectives for the next generation of internal combustion motor are: lightweight design, consumption reduction, and reduction in manufacturing costs. On the basis of direct injection, downsizing, and charging, start/stop respectively cylinder shutdown strategies, a consumption reduction potential of 30% is assumed. Downsizing comprises the reduction of the cubic capacity of the motors to an extent that the same are characterised by approximately the same power as the larger motors before, after their efficiency has been increased. In this, the efficiency is increased through turbochargers or improvements to the motor controller. This increases the specific power at less fuel consumption and emissions, but higher combustion pressures, which results in the requirements for the materials increasing. Charged petrol motors with a low cubic capacity provide weight advantages and low friction power losses. However, on the basis of increasing the combustion pressure, the component strength of crank drive and engine block will be a decisive factor in the fields of design and material selection. For future diesel motors peak pressures of up to 230bar are being considered. Experts regard the potential of today’s conventional aluminium pistons as being exhausted. The engine block is made of flake graphite cast iron or light metal (aluminium). There has been a tendency towards light metal in recent years. On the basis of the smaller cubic capacities, the weight advantage of aluminium will be decreased so that the higher costs together with the higher loads may again result in decisions in favour of iron. The higher power density achieved by means of downsizing will result in higher exhaust gas temperatures in petrol motors. Exhaust gas manifolds and turbochargers are critical components in this context. On the basis of limitations of the installation space and combustion adjustments, structural solutions are mostly very limited for these components. Thus, those materials that are able to comply with these requirements have to be further developed.  

 Power train hybrid / electric drive

The electrification of the power train is a promising option to reach the challenging targets for future vehicles. Electrical machines in the power train are able to provide manifold contributions to reducing the fuel consumption, pollutant emission, and noise, as well as to improving safety, handling, and comfort. Electric motors can only be activated if the same are really required (energy management). The broad range of applications covers the range from the classic crank shaft starter generator and hybrid drive technology up to the pure electric power train. Thus, a sustainable mobility is supported by many foundations. The advantage of the high number of alternative drive concepts is opposed by the disadvantage of energy accumulation in battery concepts (NI/MH, Li-Ion) that are as numerous. Breakthroughs are needed in duration of the charging procedure, sufficient range, and costs. Components of high-performance electronics, such as chargers or voltage converters, work on a high thermal level. In order to ensure an ideal efficiency, liquid filling and dissipation of thermal energy are absolutely mandatory. Double-wall cast for electric motors, battery or gearbox housings allows for coolant or lubricant transportation. All components have to be light-weight in order to compensate the weight of the heavy batteries. The compound cast technology allows for pouring different geometric structures (e.g. tubes, profiles) into components made of steel or aluminium, magnesium, aluminium diecasting, or aluminium sand casting. 

 Challenges and potentials for the casting industry

Given the high amounts of investments and the high level of energy consumption, the casting industry will play an important role regarding the implementation of hybrid and electric drive technology.

In a hybrid vehicle, the electric motor, the battery, and the high-performance electronics are added to combustion motor and gearbox. The number of components is higher than in the conventional drive and pure electric drive. In the pure electric drive, the components of the combustion motor are not applicable, which is partially also true for the components of the gearbox, so that potential cast parts are no longer required. Alternatively, cast components for electric motors, controllers, and chargers offer new potentials. In case of electric motors, the power strongly depends on the temperature of the solenoids. Thus, the optimisation and integration of oil and water cooling channels into cast housings is a challenge for casting technology. As opposed to the engine block, it is not the operational strength that is the decisive factor for the housings of electric motors, but the thermal conductivity, at which the same in turn strongly influences the motor power respectively power duration.

The challenges for the field of lightweight design are increased by means of the optimisation of the combustion motors (downsizing or range extender), and the load of the individual components is also increased. The use of hollow cast crankshafts is an attractive solution in the field of lightweight design for motor components. Coating procedures for cylinder running surfaces instead of cylinder bushings can also provide a contribution to lightweight design of engine blocks.

Materials to be used in higher temperatures for exhaust gas manifolds and turbochargers are also a challenge in the field of materials development.

The main requirements for the casting industry are materials and methods development for optimised lightweight design, optimisation of casting procedures by means of simulation, and use of connection technologies and compound casting for ideal material selection.  

 

References

 1. http://www.georgfischer.com/2/11/124/8196/8212.asp

2. http://www.ecodesign.at/einfuehrung/allgemein/produktleben/index.de.html

 This article is based on a paper entitled ‘Influence of hybrid and electro mobility to the foundry industry – changes and challenges’ by Leopold Kniewallner, Miro Dzinic, Ilias Papadimitriou Georg Fischer Automotive AG, Schaffhausen. The paper was presented at the 50the International Foundry Conference in Portoroz, Slovenia, September 2010.


Source: Foundry Trade Journal



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