Bosch sees future requiring multiple powertrain technologies; the larger the vehicle, the more the electrification
|Powertrain technologies outlook up to 2020. Click to enlarge.|
At the company’s 61st Automotive Press Briefing in Boxberg, Germany, Bosch senior executives outlined the company’s view on the general future of automotive technology—“efficient and increasingly electrical”, and provided a thumbnail of the way they see—and thus are developing products for—sector-specific technology trends.
In general, said Dr. Bernd Bohr, Chairman of the Bosch Automotive Group, the pace of development continues to pick up, in the form of powertrain electrification and the automation of driving. Bosch does not believe there is just one powertrain solution for the future; most of the cars on the world’s roads are still running on diesel and gasoline, and things will stay that way for the rest of the decade, Bohr noted. However, “slowly but surely”, the number of alternatives is growing.
By 2020, Bosch expects to see new vehicle sales reaching some 110 million units worldwide, with 12 million of them with an electrical powertrain. This latter figure will grow gradually throughout this decade, with the growth curve becoming ever steeper in the next.
Therefore, Bohr said, Bosch aims to develop lithium-ion batteries that will at least double the range of current electric vehicles and at half the cost per kilowatt-hour. “This is the best possible way to promote the purchase of electric vehicles.”
While policies worldwide are tightening emissions and fuel economy standards, the strictest standard of all is expected in Europe in 2020, Bohr said—average fleet CO2 emissions of 95 grams per kilometer.
How can this be achieved technically? To put it in a nutshell: the larger the vehicle, the more electrification will be required.—Dr. Bernd Bohr
More specifically, he suggested, in the sub-compact class, gasoline and diesel powertrains will be so efficient that the emissions of these vehicles will be lower than the 2020 CO2 target, even without electrification.
Only the diesel engine will achieve this in the compact class, but the gasoline engine will come close. In order to further reduce its CO2 emissions in this vehicle class, the gasoline engine will require a low-cost, basic hybrid solution.
Even with optimized internal-combustion engines, large vehicles will not achieve the CO2 target. By 2020, such vehicles will need to be equipped with higher-performance hybrid systems.
Bosch is developed appropriate technical solutions for each element in the above scenario as part of its “seven-point program”:
By 2020, the goal is to reduce the fuel consumption of diesel and gasoline engines by as much as 20% over 2012 levels. This will be done with a broad range of efficiency-enhancing technologies, including the turbocharging of downsized engines.
Automating the manual transmission, for example with the eClutch. The electric clutch shifts into neutral whenever the driver is not accelerating. This reduces fuel consumption by about 5%.
Enhancing the start-stop system to make it a coasting assistant. Bosch also uses the navigation function as a sensor of the outside world. The navigation system can preview upcoming speed limits and terrain, which in turn enables drivers to release the gas pedal well ahead of town limits or bends in the road. On highways, this can result in fuel savings of up to 15% in real driving conditions, Bosch suggests.
Hybrid powertrains for the mid-sized segment. Bosch calls its solution the boost recuperation system, or BRS for short. It goes one step further than coasting, enabling regenerative braking. This results in fuel savings of up to 7%.
Hydraulic hybrid drive for passenger cars. (Earlier post.) 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. In cities, the system can reduce fuel consumption by 45%. In normal driving conditions, the reduction is 30% on average.
Strong hybrid systems for larger vehicles, which reduce fuel consumption by up to 25%.
Plug-in hybrids. Gasoline or diesel consumption can be reduced by 50% over the course of the driving cycle.
We have not even talked about the purely electric drive yet. We are supplying it for the first time as a complete solution for the Fiat 500e. Equally, our plug-in hybrid system is debuting in the Porsche Panamera. By the end of 2014, we will already be working on 30 orders related to powertrain electrification. While these projects are not yet intended immediately for the mass market, they are paving the way for such a market, also psychologically. They represent a new kind of driving experience, one that is electric, noiseless, and comfortable. This experience is decisive.
For this reason, in an end-customer survey we conducted with Opel, we let people drive electric vehicles first before asking them any questions. Once customers have tested the cars, their willingness to pay increases with the size of the vehicle. In particular, drivers of large vehicles appreciate the possibility of purely electric driving in cities. This is a clear vote in favor of the plug-in hybrid, as well as a result that is compatible with the CO2 scenario I have already described. The technical requirements resulting from stricter environmental standards, particularly the electrification of larger vehicles, appear to be just what customers want. And this is a good thing. After all, there can be no electric driving without customers who are willing to pay for it.—Dr. Bernd Bohr
Apart from powertrain electrification, said Dr. Rolf Bulander, President Bosch Gasoline Systems, Bosch can also see potential for using economical CNG powertrains in all vehicle classes. When natural gas is burned, roughly 25% less CO2 is released than with gasoline. However, in order for the market to continue to grow, the infrastructure must be significantly expanded.
Bulander added a few more specifics to the general outline of more efficient combustion engines, with a focus on spark-ignition systems, “which require the most progress.” Bulander briefly described three possibilities for achieving CO2 values in small cars with gasoline engines:
Cost-efficient automation of manual transmission, for a 5-6% benefit.
Turbochargers in the subcompact class. Only with turbochargers can engines be downsized, he said, which can potentially offer a 7-8% percent fuel saving. If this is combined with a modern gasoline direct injection system, the fuel saving can be as much as 15% 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.
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.
Bosch will combine these possible solutions with further improved gasoline direct injection technology.
Our current assumption is that compact cars with spark-ignition engines will emit less than 85 grams per kilometer in the future. We will also further modify the systems for diesel engines in this vehicle segment—for example, by making combustion more efficient with the help of increased injection pressure or the introduction of low-pressure exhaust-gas recirculation in a wide range of applications. We will rigorously continue to refine the high-torque diesel engine with Bosch products, particularly as regards friction loss and charge cycle. In addition, performance is increasing relative to engine size. In this way, the emission values for diesel will be well below the 85-gram mark for CO2 emissions.—Dr. Rolf Bulander
Bulander said that start-stop systems will be installed in 70% of all new cars in western Europe by 2017. Bosch’s 48V boost-recuperation system (BRS) takes the start-stop system one step further closer to the hybrid world.
BRS will be deployed in the compact class, in which price competition is very stiff. The BRS electrical components support the engine with an additional output of 10 kW, but at 0.25 kWh, the capacity of the battery has been kept on the lean side. By having part of the onboard network run on 48 volts, Bosch maximizes energy recovery through regenerative braking. After the car has braked five times, the system will have completely recharged the lithium-ion battery, Bulander said.