There is a crying need to control emissions; probably more than ever before, given the rapid rise in vehicular pollution and the stringent regulations governments across various countries are imposing on the amount of emissions permissible from the automotive sector. The automotive industry, while being one of the largest contributors to the economic growth of most countries, also happens to be one of the top reasons for emission of harmful gases. It is for this very reason that most countries are cracking their whip on the automotive industry to cut harmful pollutants. This is especially significant, since the Indian automotive industry is going to skip one level of emission standard and go to Bharat Stage VI (BS VI) standards directly from April 1, 2020.
It should be noted that the industry is initiating a number of steps to address the issue of reducing emissions with regards to the internal combustion engine (ICE). OEMs and the entire supplier ecosystem is working on solutions to increase the overall efficiency of petrol and diesel powertrains, while also improving other complementary components to perform better. There has been increasing collaboration among industry stakeholders to bring out solutions that conform to newer emissions standards. The role of engineering service providers as well as test and validation companies is gaining prominence so that they are able to offer newer models and designs with better efficiency in shorter development times.
Beyond the work being carried out in the ICE arena, part or full-electrification of the powertrain is also being looked upon as a viable solution for the overall reduction of emissions. The addition of an electric motor to a combustion engine, or the complete replacement of the ICE to an electrified motor will be the future of powertrains.
In terms of the traditional ICE engine, companies are adopting a series of technologies to make both petrol and diesel engine modes efficient – from the performance perspective, as well as from reduced emissions. Some OEMs have even vouched to stop making diesel engines in future, since they are a little more polluting than their petrol counterparts. However, the main methods of reducing emissions are being carried out through downsizing of engines, using forced induction technologies, weight reduction, direct fuel injection, exhaust recirculation technologies and alternate fuels.
It is being observed that vehicle manufacturers are developing engines that have a lower cubic capacity than earlier but with improved power ratings that are enabled by complementing technologies. Four-wheeler manufacturers are using the method of mating forced induction technologies like turbocharges and supercharges to the engine, which increases power and torque outputs, while reducing the amount of Nitrogen Oxide (NOx) emissions.
In terms of petrol engines, direct injection is gaining prominence for small engines in passenger cars, from the more common multi-point fuel injection (MPFI) that is prevalent today. However, there would be a requirement to develop low pressure injection systems that would be appropriate for small capacity engines, and would also keep costs low. The current focus of development work is on mechatronic approaches in which component attributes are optimised by combining them with intelligent software functions.
Diesel engines are mostly using one of two technologies to cut the level of emissions – Selective Catalytic Reduction (SCR) or Exhaust Gas Recirculation (EGR) technology. SCR technology uses an aqueous urea-based fluid that is sprayed into the exhaust stream to break down dangerous NOx emissions into harmless nitrogen and water. Additionally, improvement in fuel economy is also achieved by using the SCR technology, since all the emission control processes are carried out separately in the exhaust system. Meanwhile, EGR, as the name suggests is an emission control technology that recirculates the exhaust gas into the engine allowing significant NOx emission reductions from most types of diesel engines.
HARDWARE & SOFTWARE
The move towards newer emission norms means that the engine will now have fewer components, which have to be more modular in nature and also need to be flexible to be assembled onto multiple vehicle models or engine sizes, in order to offer better business cases to manufacturers. These components will also need to be smoother and cut noise levels sharply, while also being lightweight and compact to fit into smaller engine compartments. In addition to all these requirements, the new emission standards also pose another challenge in the engines, which is addressing the increased heat being generated.
The answer to a number of these challenges is being addressed by the use of alternate materials in the construction of engine components. We are witnessing an extensive use of aluminium, and in some cases composites and special plastics are replacing a large amount of metal parts. These alternate materials, in most cases, also happen to have a lower carbon footprint than traditionally-used material. Such features drastically reduce the greenhouse gas emission of the vehicle.
With all these mechanical components becoming smaller and modular in nature, there is a need for improved electronic control of the performance of these components. The vehicle’s electronic control unit (ECU) needs to shoulder additional responsibilities in smartly controlling the various aspects of the vehicle to make it more efficient. The electronic brain will have to control fuel discharge more precisely, while also cooling the engine better and keeping a track of the utilisation of power for other components. Features like automatic start-stop, improved stator generates, and 48 V electrical systems are being used by OEMs to make their vehicles more efficient, and all these require electronic monitoring at all times. The amount of codes and software going into the vehicle is also growing at a rapid pace.
A number of automakers are offering their vehicle models with hybrid systems, which can vary in the level of electrification offered. While certain systems just recoup a small amount of power back to the battery, there are plug-in hybrids that have an electric motor in addition to the ICE to power the vehicle alternatively or together. Then we have full-electric vehicles that are seeing increased penetration in a country like India. EVs offer zero tailpipe emissions, and are becoming the answer to future mobility requirements. EV manufacturers are currently working hard on designing and developing models that offer the same or improved appeal that ICE vehicles provide, in order to increase their adoption. These companies are also working on battery technologies that would result in better performance of batteries in Indian conditions, while being able to offer a longer driving range.
While hybridisation and electrification seem to be the eventual answer to curb emission of poisonous gases into the atmosphere, we must also consider the method in which electricity is produced in the first place. In the case that electricity is generated through coal plants, the point from where emissions are discharged changes from the vehicle to the coal plants. It is also important that the method of manufacturing carried out for EVs and hybrids is also clean, without any form of waste discharge or emissions. In addition, there is a need for power generation for EVs to be from clean sources, which would then ensure that these vehicles are in fact 100 % clean. These are the methods by which EVs can be made to offer zero emissions, when the ‘Wheel-to-Well’ process of the vehicles is pollution free.
It is clear that emission norms are only going to get more stringent in future, for which there will be a need to keep improving ICE powertrains, while also adopting EVs. It is not the engine alone that will need to get efficient, but also supporting factors of transmission, electricals, electronics and electrification of components. The next few stories look into the various aspects and areas, where the automotive industry is looking at implementing new technologies, with the aim to control the level of emissions within the automotive industry. These technologies are aimed at improving the combustion of the fuel, be it petrol or diesel, while also focussing on electrification to bring about a complete arrest of carbon emission altogether.
(Inputs from DICV, Bosch, TU Graz, SEG Automotive)
TEXT: Naveen Arul