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Bosch powertrain: what will drive us in the future
Dr. Rolf Bulander,
President Bosch Gasoline Systems,
and Dr. Markus Heyn,
President Bosch Diesel Systems,
at the 61st Automotive Press Briefing in Boxberg, June 2013
- June 17, 2013
- Mobility Solutions
- Images: 2
The European Union’s fleet targets for 2020 are now cut and dried. The EU commission’s proposal is now official: 95 grams CO2 per kilometer. And just two years from now, in 2015, vehicle fleets will be restricted to an average CO2 emission of just 130 grams per kilometer.
Even if other economic areas, such as the U.S. and China, have also adopted legislation to reduce CO2, the EU’s target for 2020 remains the most ambitious. Bosch automotive technology will play a crucial part in making vehicles of all classes fit for the future. Further improvements in consumption are possible, but they come at a cost which, in some cases, is considerable. But we don’t want to just talk about cost – above all, we want to talk about emotion. By electrifying the powertrain, automobiles offer a completely new driving experience. The vehicle’s maximum torque is available from the first few meters, and in the case of hybrids, the electric motor offers additional power during acceleration, thus creating a “boost effect”.
Many solutions: combustion engines, electrification, CNG
Whether customers will be driving a car with a combustion engine or an electric motor in the future will depend very much on the class of car they drive. In the case of small cars, we believe modifications to the engine will be sufficient. Improved injection technology, turbochargers, and downsizing combine low cost with high efficiency.
In the case of mid-sized powertrains, Bosch is also working on technology for even cleaner and more efficient engines, which should nonetheless still be affordable. We believe there is still potential here to refine and also develop new engine components with which we can further optimize the combustion process. In addition, we’re working on new systems which, for example, effectively recuperate braking energy and allow mild electrification of the powertrain.
For powertrain technology in the premium class, we have to do more to achieve the CO2 targets. Bosch is developing efficient plug-in hybrid systems that allow up to 60 kilometers to be driven solely on electric power. This allows lower emissions to be achieved even in SUVs. These systems will mean additional costs, but they will also provide additional benefits, since the plug-in hybrid adds additional sheen to the premium segment. Equipped with this powertrain, a car is almost noiseless in electric mode, yet it has the range of a car with an internal-combustion engine. In addition, the torque of the additional electric motor makes the car even more dynamic.
Apart from powertrain electrification, Bosch can also see potential for using economical CNG powertrains in all vehicle classes. When natural gas is burned, roughly 25 percent less CO2 is released than with gasoline. Our systems also offer high levels of customer benefit and low additional costs. However, in order for the market to continue to grow, the infrastructure must be significantly expanded.
Efficiency from downsizing to turbocharger
I would now like to take a closer look at what we can still achieve with our components in the subcompact class. For the most efficient vehicles in this segment in 2012, Bosch can see potential further savings of as much as 20 percent. At present, the most advanced diesel vehicles in this class emit just 81 grams of CO2 per kilometer. Our broad diesel product portfolio features the most efficient combustion process, thus allowing us to achieve optimum CO2 values. Our most advanced gasoline vehicle manages 99 grams of CO2 per kilometer. Given this excellent basis, we are sure that engine-based solutions will be enough to achieve the EU targets.
I would like to present some of these solutions to you now. Our focus here is on spark-ignition engines, which require the most progress. I will now show you three possibilities for achieving the CO2 values in small cars with gasoline engines.
- First, cost-efficient automation of manual transmission. We believe this has a reduction potential of roughly five to six percent.
- Second, turbochargers in the subcompact class. Only with turbochargers can engines be downsized, which can potentially offer a seven to eight percent fuel saving. If this is combined with a modern gasoline direct injection system, the fuel saving can be as much as 15 percent compared with a port fuel injection system. In addition, the turbocharger provides more torque, and thus optimum performance. It allows load point and valve lift to be shifted for de-throttling. This increases the engine’s efficiency.
- Third, optimizing combustion by combining an increase in compression ratio with cooled exhaust-gas recirculation. This modification would be efficient, reducing CO2 emissions by roughly one-tenth.
Hydraulic hybrid: alternative powertrain with a wide range
A further possibility for increasing efficiency in the subcompact class is the world’s first hydraulic hybrid powertrain for passenger cars, which Bosch and PSA are working on. It is based on a classic internal-combustion engine with additional hydraulic components and a pressure accumulator filled with nitrogen. This hybrid system can support gasoline and diesel engines where they do not work efficiently – when accelerating, for example, or in stop-and-go traffic. Its strengths especially come to the fore in cities. There, the system can reduce fuel consumption by 45 percent. In normal driving conditions, the reduction is 30 percent.
The reason we can reduce consumption so dramatically is that we very efficiently recover the energy that would otherwise be lost. The specialist term for this is recuperation.
The kinetic energy that is dissipated during braking is converted into hydraulic energy and stored in a pressure accumulator.
The decisive feature here is that this alternative powertrain does not require a battery pack. This reduces the system’s additional weight to under 100 kilos. This makes the hydraulic hybrid economical, and above all variable. Its use need not be restricted to municipal vehicles. We also see it as an option in other segments, right up to light trucks.
At the same time, this powertrain unites many of the familiar advantages of an electric car. It can drive short distances completely emissions-free, and its boost effect adds to driving enjoyment. This boost effect comes about when the internal combustion engine is running and the hydraulic pressure accumulator is discharged at the same time. In addition, the powertrain allows the load point of an internal-combustion engine to be shifted, thus enabling its operation in the most efficient area of the characteristic map. Moreover, there are no worries about range. What we have here is an alternative powertrain that actually increases a car’s range by a significant amount – because it reduces fuel consumption.
Boost-recuperation system and e-clutch: the link to the hybrid world
Our powertrain electrification work pursues similar objectives. This work starts with the further standardization of start-stop systems, which will be installed in 70 percent of all new cars in western Europe by 2017. But we also want to try out new solutions. Our boost-recuperation system (BRS) will serve as an example. This 48 volt system takes the start-stop system one step further, and closes the gap to the hybrid world – a gap which is still quite wide.
You will see the BRS in the compact class, in which price competition is very stiff. In other words, it will have to be affordable as well as efficient. We can ensure this by deliberately adapting its components. We use electrical components that support the engine with an additional output of ten kilowatts. At 0.25 kilowatt-hours, the capacity of the battery has been kept on the lean side. But by having part of the onboard network run on 48 volts, we make the most of maximum energy recovery through regenerative braking. After the car has braked five times, the system will have completely recharged the lithium-ion battery.
This energy can be used to supply the electrical power consumers in the onboard network as well as to provide a dynamic boost to the internal combustion engine when starting off or accelerating. On the subject of the BRS, it’s also worth mentioning the e-clutch, an electrically operated clutch. With this system, only the clutch – not the transmission – is automated. This allows the engine to be disengaged from the powertrain when no power is needed for propulsion. This will not only help drivers to save fuel, but also make driving more convenient. In traffic jams, they will be able to start off in first and second gear without using the clutch. In other words, the e-clutch gives drivers a kind of automatic transmission for low speeds. In addition, the electronic clutch can shift to idle if the driver’s foot is taken off the gas. This makes fuel-saving coasting possible with start-stop.
The way this works is simple. Our system detects when a driver is not accelerating downhill, disengages the clutch, and in this way prevents the classic braking effect of the engine. Thanks to the gradient, speed remains constant. You can already manually simulate this effect to some extent by disengaging the clutch on a downhill stretch. In the future, the system will automatically assume this function. This is technically sophisticated, but worthwhile, leading to a seven percent reduction in fuel consumption.
Strong hybrid: up to 25 percent lower consumption
In his keynote presentation, Mr. Bohr made it clear that entry-level hybrid systems such as this are part of the individual mobility of the future. By 2020, we expect to see 12.1 million vehicles with an electrical powertrain. Given this mobility scenario, I would like to show you what technology Bosch already offers for the current generation of hybrid vehicles. We are already ramping up production, and in this way lowering costs. Moreover, with the strong-hybrid systems currently made by Bosch, drivers can reduce their consumption in the new European driving cycle by 15 to 25 percent. Driving a Bosch strong-hybrid system, and depending on the size of the battery, drivers can cover short distances solely on electric power – which means with zero emissions and without any engine noise. One outstanding example of this is the diesel hybrid developed by PSA and Bosch. It combines the power of an advanced diesel engine with the economy of electrical components.
The size of the car hardly matters. Bosch can provide a complete powertrain concept and adapt it to the requirements of any vehicle. This shows the wide range of our technical systems. For strong-hybrid vehicles, we have electric motors covering the range between 20 and 40 kilowatts. For hybrids, Bosch has rechargeable lithium-ion batteries with a storage capacity from 0.8 to 1.5 kilowatt-hours. With the DC/DC converter, we also offer the right link between the electric motor and the battery. It therefore makes no difference whether the car to be equipped with a strong hybrid is a small compact car or a station wagon – Bosch has the right solution for both.
Plug-in hybrid: the future of the premium class
This is also a promise we can keep when it comes to plug-in hybrids. In this case, however, we have taken powertrain electrification one step further. Drivers can cover distances of up to 60 kilometers solely on electric power, and this at speeds of up to 120 kph. This allows an energy-cost saving of up to 90 percent, provided users consistently charge up at the socket. But even customers who do not have a fully charged battery before each journey will benefit from a plug-in hybrid. With our systems, we estimate that fuel consumption in the new European driving cycle can be reduced by at least 50 percent.
This is why the electrical components we use here are more powerful. The Bosch electric motors in these systems have an output of 30 to 80 kilowatts, and the battery capacity is as much as 12 kilowatt-hours. They can be used in cars ranging from middle-class sedans to electric SUVs and sports cars. This scalability shows just how important plug-in hybrids will be in the future. When it comes to the CO2 targets for 2020, a high level of electrification is the only option for the premium class.
The fact that they can drive up to 60 kilometers solely on electric power will mean that drivers using a Bosch plug-in hybrid system are ready for even more ambitious environmental laws.
Electromobility: Bosch offers single-source powertrain
Of course, customers can also enjoy these benefits when our technology is installed in fully electric cars. Here again, I would like to give you a concrete example: the Fiat 500e, for which Bosch supplies the complete powertrain. In other words, we not only manufacture components, but also have the expertise to put them together to form a complete electrical powertrain. Let’s have a look at those components in turn:
- Thanks to the SMG 180/120 electric motor developed by Bosch, the Fiat 500e delivers 80 kilowatts. The permanent magnet synchronous motor is the powertrain’s powerhouse. Right from the start, it offers 196 Newton meters of torque.
- The central interface between the electric motor and the battery is the Bosch INVCON 2.3 inverter-converter unit. This component is the electrical powertrain’s brain. This is because the system converts the direct current stored as energy in the battery into alternating current for the electric motor, and vice versa. The more efficiently such a power electronic device works, the greater the electric range.
- Thanks to the Bosch battery pack, the Fiat 500e has a range of some 140 kilometers. The traction battery comprises prismatic cells with a total capacity of 24 kilowatt hours, and can be completely recharged in less than four hours.
CNG powertrains: an alternative to the alternative
But before I close, let me take another look at the present and near future. Bosch has yet another alternative powertrain up its sleeve, one that is becoming a true alternative. I’m speaking of the CNG powertrain. Up to now, this has tended to be found in city buses and light delivery vans. But in the future, we will increasingly see CNG powertrains in passenger cars and commercial vehicles, also in conjunction with diesel. For drivers, CNG can be worthwhile from an annual mileage of 7,000 kilometers – practically for everyone, in other words. This is mainly due to CNG’s favorable price, which is up to 50 percent lower than the price of gasoline. Even now, it allows us to reduce CO2 emissions by 25 percent – in the case of methane generated in biogas plants, this number is considerably higher. In our view, this makes natural gas an easily available, eco-friendly alternative worldwide.
This is why Bosch also offers cutting-edge systems. You can already find our CNG technology in series-produced vehicles made by VW, GM, Fiat, and Tata. Among the components we supply are the world’s smallest and lightest CNG injector and the fastest temperature sensor.
What is so ingenious about this technology is that you don’t notice it when you’re at the wheel. Today’s natural-gas-powered vehicles offer consistent performance, regardless of whether they are driven in CNG or gasoline mode. Even the switch from natural gas to gasoline is imperceptible.
When driving a Bosch CNG system, the main difference you notice is at the pumps. Here, customers save money once more, even in comparison with other CNG solutions. The Bosch system also starts in CNG mode when cold, and thus enables maximum usage of inexpensive natural gas. The systems sold by other suppliers have to warm up conventionally, and first drive on expensive gasoline for many miles. But with our technology, customers almost always drive on inexpensive natural gas.
But it’s time to leave the technical details and return to the big picture. Our advanced CNG powertrains are a transitional technology on the road to green mobility. You can already buy a vehicle equipped with a Bosch CNG powertrain, and already have a car that is efficient and eco-friendly at the same time. And with the same aims in mind, we are continuing to further improve conventional internal-combustion engines. And let’s not forget one thing: Bosch is working to make electrical powertrains affordable for everyone. In other words, we supply technology for individual mobility – now and in the future. In doing so, we remain true to our strategic imperative: “Invented for life.”
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The Bosch Group is a leading global supplier of technology and services. It employs roughly 375,000 associates worldwide (as of December 31, 2015). The company generated sales of 70.6 billion euros in 2015. Its operations are divided into four business sectors: Mobility Solutions, Industrial Technology, Consumer Goods, and Energy and Building Technology. The Bosch Group comprises Robert Bosch GmbH and its roughly 440 subsidiaries and regional companies in some 60 countries. Including sales and service partners, Bosch’s global manufacturing and sales network covers some 150 countries. The basis for the company’s future growth is its innovative strength. Bosch employs 55,800 associates in research and development at 118 locations across the globe. The Bosch Group’s strategic objective is to deliver innovations for a connected life. Bosch improves quality of life worldwide with products and services that are innovative and spark enthusiasm. In short, Bosch creates technology that is “Invented for life.”
RF00195 - June 17, 2013