Trends and innovations in automotive lightweight

As the automotive world moves to meet the next generation of stringent emission and fuel economy targets, all aspects of the internal combustion engine (ICE) are being analyzed under a microscope. Inherently, ICEs come with inefficiencies. The efficiency of an ICE typically varies from 18% to 40%. This efficiency is a function of friction losses, pumping losses, and wasted heat. Currently, global automotive original equipment manufacturers (OEMs) are hard at work trying to attack these issues with various solutions to achieve incremental gains.

The leading trend is getting more power from less space, also known as downsizing. Due to the leading downsizing initiative, there is a reduction in the number of cylinders and displacement while providing the necessary power output to the customers. The secondary reaction to downsizing is moving from a naturally aspirated fleet to a turbocharged fleet. To gain efficiencies and power output, better control systems are a necessity. Hence, valvetrain and fuel delivery systems are heavily controlled and optimized to meet emissions and fuel economy targets.

Figure 1—Powertrain Market: Evolution of Average Engine Displacement, Global, 2012–2022

For the Chinese passenger vehicle powertrain mix in 2015, about 89% of the engines were gasoline engines and less than 10% were diesel engines. Of the ICEs sold in China in 2015, 72% had a displacement that was below 1.6 liters and 20% of engines sold were between 1.6 and 2.0 liters. In South Korea, 46% of engines sold were below 1.4 liters displacement and 38% of engines sold were between 1.5 and 1.9 liters. In total, 84% of South Korean engines had a displacement below 1.9 liters. In India, about 62% of diesel engines were between 1.0 and 1.6 liters, and gasoline engines were close to 48%. About 34% to 36% of gasoline engines sold in India are expected to be below 1.0 liters by 2017. The trend in the Asian market is that the majority of the passenger vehicle engines will have displacements below 1.5 liters after 2020.

The downsizing of ICE will provide consumers with some of the most efficient ICEs the world has ever seen in the mass market. This can also be seen as a trend towards ICEs moving away from being a primary propulsion source to a secondary power source.

Downsized Engines to be Turbocharged

Figure 2—Global Engine Forecast, 2014-2022

There is a clear growing trend in the global sales forecast for turbochargers. As the engines are downsized, turbocharger sales are increasing to satisfy the customers’ power thirst. There is a clear global growth forecast between 1 and 2 liter displacement engines. The correlation between turbochargers and downsized engines is very clear and should not be overlooked. Global Tier I suppliers like Honeywell, Continental, Valeo, Bosch/Mahle, and BorgWarner are aware of this trend and are in the marketplace ready for OEMs. With Valeo as supplier, Audi has also launched an electric supercharger in its 2016 SQ7 with a 4 liter diesel engine that emits a relatively low 194g CO2 per km in the New European Driving Cycle (NEDC).

Controlling Fuel & Valvetrain

Better valvetrain controls with variable valve timing (VVT) for intake and exhaust valves, variable valve lift (VVL), and direct injection technologies enable better combustion and help reduce pumping losses. Gasoline and diesel engines both have advanced direct injection technologies to optimize the combustion efficiency.

Figure 3—Fuel Injection Systems Forecast, Global

Direct injected gasoline engines will be seeing a sharp growth, amount to up to 38-39 millions in 2022. Diesel engines will see a marginal growth in volumes produced, but will continue to lose their share to the rapidly growing direct injected gasoline engines (figure 3).

The control and durability of the direct injection system provides engineers the dynamic ability to optimize ICEs for the customers’ needs. There is an unquestionable trend towards gasoline ICEs with direct injection systems.

Dual overhead camshaft (DOHC) is the dominant valvetrain technology today and it is expected to continue its domination even  up to 2020. DOHC provides engineers the   ability to control the intake and exhaust valves far better than a single overhead camshaft(SOHC) or over head valve (OHV) valvetrain systems. With stronger emission targets, valve events have to be made more precise and flexible, and therefore the growth of DOHC is logical and should be expected.

The leading growth areas in powertrain innovations are ICE downsizing, turbocharging, direct injection, and valve train controls. These innovations, when combined, provide automotive OEMs a unique set of synergies with which they can achieve emission targets, fuel efficiency gains, and customer satisfaction.

Powertrain Lightweight Solutions

Considering the significance of downsizing, direct injection, and the other aforementioned technologies, it becomes imperative to look at another key area that OEMs are striving to improve—their limits to, for gaining on those extra few kilometers to a liter- Weight reduction.  To put this into an emissions perspective, it is estimated that every 50kg of weight reduced cuts down CO2 emissions by 4 to 5 grams on average for a 1500kg vehicle. Frost & Sullivan studies indicate that a vehicle with average weight of 1500kg has the potential to lose up to 25% of its weight by 2020, and consequently, powertrains potentially could be about 8% lighter than their current levels with usage of lighter materials assuming minimum weight impact from the deployment of emission reduction technologies.

The key power train elements where OEMs will focus on reducing weight will be the engine, transmission, exhaust, fuel system, casing, batteries, and motors. Studies reveal that it is possible to reduce about 100kg in the medium term, enabling savings of about 8g CO2. The key drift in material technology is likely to happen with heavier engine components like cradles, engine blocks, cylinder heads, and gears.  While engines will constitute more of Advanced High Strength Steel (AHSS), with aluminum and magnesium replacing steel, steel-based transmission parts are likely to shift towards the use of polyamides (PA). Both cases will offer weight reduction possibilities of up to 40% in the medium term.

Table —Powertrain Lightweight Potential, Global, 2015

Component

The key to OEM lightweighting strategies is targeting the right segment for application. While larger segments have the price cushion to pass on compliance costs to owners, mid-size cars will have moderate compliance costs that will impact purchasing decisions if passed on to buyers. Smaller segments have price-sensitive buyers, but the relative compliance costs also have a smaller impact.

Innovations in Noise, Vibration, Harshness

Engine innovations such as stop-start systems, hybrid and plug-in hybrid vehicles, cylinder deactivation, and turbocharging technologies place greater requirements on noise, vibration and harshness(NVH) of the vehicle due  variations in the layout and transfer path. Such challenges have led to innovations in engine mount and noise cancellation technologies. Honda was one of the first OEMs to mass market active control engine mounts in their cylinder deactivated V6 engines. Led by German manufacturers, OEMs in Europe are adopting sophisticated active mounts on premium vehicles. Audi and Porsche have fitted unique and sophisticated electromagnetic oscillating coil type and magnetorheological type engine mounts respectively on Audi S8 and Porsche 911. These vehicles also come with active noise cancellation, which counteracts unwanted noise through destructive interference and almost eliminates any air-borne noise from the vehicle. The epitome of innovation is within the active exhaust system, where microphones are installed on the exhaust to absorb unwanted frequencies and speakers to produce characteristic sound. The speakers can be tuned to produce an authentic signature sound, a sound your vehicle can change according to the driver’s mood or vehicles mode. Exhaust sound engineers from Eberspacher previously designed this system, which is currently being tested in Europe. A Dual Mass Flywheel (DMF) supplied by companies like ZF and Schaeffler is a growing technology that effectively isolates torsional vibration of engines and prevents them from getting passed on to the driveline.

Beyond Euro 7—Exhaust Gas Heat Recovery Innovations

On average, two-thirds of fuel energy is wasted through the exhaust gases and the cooling liquid. To minimize fuel consumption and engine emissions, the conversion of exhaust heat energy shows great potential. Waste heat can be indirectly utilized for power generation using a Rankine cycle, or directly used for thermoelectric generation.

A thermoelectric generator (TEG) converts heat directly into electricity using the Seebeck effect in a simple and reliable way. Currently, various integration configurations are being evaluated and 200W to 1000W energy recoveries have been achieved. Cost and technology infancy are the major barriers for TEGs. OEMs such as BMW and Ford are leading development programs, with the former likely to be the first to commercialize this technology post 2020. Fuel economy gains of 3% to 7% are achievable through TEG systems.

Indirect method of exhaust heat recovery using the Rankine Cycle is based on steam generation in a secondary circuit using the exhaust gas thermal energy to produce additional power by means of a steam expander. A Rankine Cycle engine does not impact the engine pumping losses by much when compared with turbo-compounding. Also, with respect to a TEG, a Rankine Cycle engine provides higher efficiency of heat recovery. However, cost, weight, and reliability are the major challenges for Rankine Cycle recovery systems and they are unlikely to be commercialized before 2020. Although BMW and Ford have demonstrated Rankine Cycle engine concepts, Honda is one of the OEMs looking to pursue using the Rankine Cycle for hybrid applications in production vehicles. Vehicle power output can be boosted by about 10% to 15% using Rankine Cycle engines.

Exhaust heat recovery (EHR) systems are considered to be one of the key energy recovery technologies preferred (alongside energy recuperation) by OEMs towards 2020.

Modular Architectures and Platforms

OEMs worldwide are also adopting strategies to share components, systems, and modules among different cars and segments. While the primary motive behind this move is cost reduction, improved driving dynamics, reduced CO2 emission, reduced friction, and overall weight reduction are also targets. VW group, for example, aims to produce almost all its vehicles on five modular architectures, namely MQB (for transverse mounted engines), MLB (longitudinal) MSB (sports cars), MEB (electric), and NSF (small cars). Through this approach, VW and other major OEMs target faster  response to latest emission regulations and changing technology trends.

The standardization of basic architectures will result in improved cost savings, which could be reused to develop modular components that can be shared across vehicles or segments. Components like direct injection systems, turbo chargers, and exhaust catalysts will have customization to meet the regulatory requirements of local markets. Costs saving from the increased use of modular components will be used in developing innovative vehicle and engine concepts and electric vehicle technology.
Modularity in powertrain and vehicle architectures is going to bring significant cost savings for OEMs and technology suppliers. This is expected to increase the focus on advanced technology in powertrains and vehicles that will result in more features, improved efficiency, and a better affordability of cars. It is expected that by 2022, the top 16 modular platforms from major vehicle manufacturers will be the underpinnings for more than 46 million vehicles worldwide.

Tougher Testing Protocols and Increased Control on Exhaust Emissions

With strong regulations and regional differences, vehicle manufacturers and suppliers face the challenge of fine-tuning powertrain and exhaust systems so that a vehicle can be compliant in all regions. The diesel gate scandal of the VW group was primarily a result of an engine family’s inability to comply with one regional regulation and it attempting to circumvent norms. This has accelerated the implementation of a Worldwide harmonized Light Vehicle Testing Procedure (WLTP), which involves a tougher testing procedure with a greater load on the engine. OEMs and suppliers have already begun vehicle and component testing, keeping the new procedure in mind. Real Driving Emissions (RDE) will also be monitored, with a provision for vehicle in-use testing using Portable Emission Monitoring Services (PEMS).

Although the new procedures will demand optimization at the powertrain and vehicle level, after-treatment systems will have significant pressure on them to clean the exhaust. Car makers like Daimler and Audi that have considerable portion of large diesel engines in their portfolio and are the pioneers of developing high efficiency NOx reduction systems and particulate filters. With the introduction of EURO 6c norms, particulate number limits will also be in force. After-treatment technologies like Selective Catalytic Reduction (SCR), gasoline and diesel particulate filters, and combined low and high pressure exhaust gas recirculation systems will be implemented by almost all OEMs in their vehicles to meet these emission standards.  The VW group has decided that it will deploy gasoline particulate filter systems in all their gasoline TSI and TFSI engines starting in 2017. With this technology, it aims to reduce the emission of soot particles by up to 90%.

Figure 4—Implementation of WLTP and Powertrain Impact

Further, apart from stringent emission standards, Europe is also attempting to improve its air quality through introduction Low Emission Zones (LEZ) and Ultra Low Emission Zones (ULEZ). The world’s first ULEZ is being implemented in London in 2020. ULEZ mandates EURO 6 standards for diesel and EURO 4  for gasoline cars. Additionally, all new taxis presented for registration have to be zero emission capable after 1 January 2018 and cannot be powered by diesel. Many European countries already have a tax structure that is aimed to lower the uptake of diesel vehicles, which essentially points to a future with fewer diesel cars on the road. Several European countries like Germany and the Netherlands have discussions on the table to make road transport petroleum free in the long term, the consequences of which are expected to be seen in the coming decade.