Navigant Research Blog

Electric Turbochargers: The Next Big Thing in Fuel Efficiency

— October 23, 2014

The key to the next major advance in internal combustion engine fuel efficiency could well be the electric turbocharger.  At a recent fuel economy technology showcase at the U.S. Environmental Protection Agency (EPA) National Vehicle Emissions and Fuel Lab in Ann Arbor, Michigan, Valeo showed off the motor-driven turbo it will supply to an unannounced automaker.  The first production applications are scheduled to begin arriving in 2016, according to the company.

The aggressive expansion of fuel efficient technologies, such as electrification, multi-speed automatic transmissions, and engine downsizing, has played a major part in increasing miles per gallon.  The average fuel economy of the American new light duty vehicle fleet has improved by almost 25% over the past decade.  Meanwhile, gasoline direct injection and turbocharging have enabled engineers to cut engine displacement by 30% or more without sacrificing the performance that drivers have come to expect.  As of the 2014 model year, approximately 75% of Ford gasoline and diesel engines globally are turbocharged while 85% of Volkswagen engines are boosted.

Response Time

Part of the concept behind boosted engines is to use smaller engines with turbochargers that provide performance on-demand.  There has always been an inherent time lag, however, between the time the driver presses the accelerator and the generation of enough extra exhaust gas to spin up the turbo and provide boost.  Mechanically-driven superchargers eliminate much of the lag at the cost of substantial friction at higher speeds.

Replacing the exhaust-driven turbine side of the turbocharger with an electric motor provides a number of advantages, most notably in packaging, responsiveness, and operational flexibility.  One of the fuel economy benefits Valeo highlights is the combination of an electric turbo with the cylinder deactivation – i.e., the ability to shut off multiple cylinders under light loads in order to improve fuel efficiency.

The fuel savings achieved by shutting off unneeded cylinders can be quickly lost when driving on roads that aren’t completely flat.  Even a mild grade can cause an engine to switch back to running on all cylinders in order to produce enough torque to maintain speed.  “With an electric turbo, the engine management system can request small amounts of boost on-demand to increase torque while climbing a grade while keeping as many as half of the cylinders inactive,” Ronald Wegener, application engineering manager with Valeo, told me.  “This can yield up to a 10% improvement in efficiency.”

Valeo has developed versions of the device for both 12V and 48V electrical systems so that the turbo can also be used as part of a mild hybrid system during off-throttle conditions.  Intake air flowing through the compressor drives the motor to generate electricity, charging the battery.  Audi is using this as one of the two forms of energy recovery on its Le Mans-winning R18 e-tron race car.  Many of the current crop of Formula One cars have also adopted this approach.  Earlier this year, Audi announced that the next-generation Q7 TDI, scheduled for model year 2016, would be its first production application of the technology.

Shrinking Engines

Electric turbochargers also provide packaging benefits to engine designers.  Traditional turbos require complex plumbing to route exhaust gases to the turbine side of the turbo and feed the boosted intake charge to the other side of the engine.  Disconnecting the turbo from the exhaust allows designers to place the turbo wherever it fits best for packaging and performance.

Executives and engineers agree that while electric vehicles will gain market share in the coming years, internal combustion engines will likely remain the dominant powertrain choice in the transportation space at least through the 2020s.  With engines continuing to shrink, it seems likely that electric turbochargers will account for a growing share of the boosted engine market in the next decade.

 

Truck Fuel Economy on the Rise

— October 20, 2014

The U.S. Environmental Protection Agency (EPA) has just published its 2014 fuel economy trends report, and though the news is generally positive, some potential storm clouds remain on the horizon for manufacturers.  While the overall average fleet fuel economy hit a record 24.1 mpg for the 2013 model year, the monthly update from the University of Michigan Transportation Research Institute (UMTRI) showed a 0.5 mpg drop in September 2014, equal to the 2012 to 2013 annual increase.

The long-term trend has definitely been upward.  Last year represented the eighth increase in the past 9 years for the American new vehicle fleet.  Automakers will have to maintain this momentum if they expect to hit the 2025 corporate average fuel economy target of 54.5 mpg.  Fortunately, attendees at a fuel economy technology showcase at the EPA emissions testing lab in Ann Arbor were all publicly confident that the targets were achievable.

As for the sudden drop in September, that can be explained by what are likely temporary market conditions that led to a significant uptick in full-size truck sales at General Motors (GM) and Chrysler.  As the 2014 model year drew to a close, combined sales of the Chevy Silverado and GMC Sierra jumped 46%, aided by incentives of up to $4,500.  Ram sales were also helped along by retail incentives of up to $3,000, as well as the popularity of the new Ram 1500 EcoDiesel.

From Steel to Aluminum

Sales of Ford’s F-series trucks were essentially flat, as the automaker began the transition to its all-new, aluminum-bodied 2015 F-150.  It appears that GM and Chrysler are hoping to grab some market share in the financially lucrative big truck segment in hopes that Ford would stumble in the complicated transition from steel to aluminum trucks.

At this point next year, even if truck sales continue to climb, we’re unlikely to see a similar drop-off in fuel economy, thanks to new technology in the segment.  The weight savings and new power plants for the Ford trucks are projected to deliver up to 20% better fuel efficiency than the steel-bodied versions.

Chrysler and GM also have to meet the new fuel economy standards.  Ram pickups are already available with ZF 8-speed transmissions, and GM is adding its first 8-speed automatic transmission to 2015 pickups with a 6.2-liter V8.  As GM ramps up production of the new 8L90 transmission, it will probably get paired with other engines as well.  GM and Ford also have a joint development program to produce 9- and 10-speed transmissions for trucks and other vehicles in the next few years.

Diesel Debuts

Chrysler is also building on the success of the 28 mpg Ram 1500 EcoDiesel by doubling production to 20% of its total production volume of trucks in 2015.  Ford is still awaiting final EPA certification on the 2015 F-150, but the 2.7-liter EcoBoost V6 is also expected to get a highway rating in the upper 20s.  GM’s new midsize Colorado and Canyon pickups are already rated at up to 27 mpg with a gasoline V6, and a diesel version is coming some time in 2015.  Ford is also offering a diesel engine option in the new Transit full-size vans that replace the E-series this year.  Ford will likely be closely following the sales trajectory for diesel engines in the Chrysler and GM trucks, as well as the next-generation Nissan Titan and Toyota Tundra, which will both be available with a Cummins-sourced 5.0-liter diesel V8.

With the huge sales volumes of pickup trucks in North America, lightweighting, advanced powertrains, and automatic stop-start, trucks will make a big contribution to reducing fossil fuel use in the next decade.

 

A Few Steps Closer to Autonomous Vehicles

— September 30, 2014

As engineers, scientists, executives, and government officials involved with transportation systems gather in Detroit this week for the annual ITS World Congress, the auto industry took another incremental step along the 60-plus-year road to autonomous vehicles.

In her keynote address, General Motors (GM) CEO Mary Barra announced that two of the technologies that are building blocks toward a driverless future will come to market in 2016.  The 2017 Cadillac CTS will be the first production car from GM equipped with vehicle-to-vehicle (V2V) communications technology.  Barra did not provide any details about exactly what sort of information would be exchanged between cars equipped with the technology, but messages will likely include alerts about brake applications, slippery road conditions, and position and speed as the vehicle approaches an intersection.

GM is the first automaker to announce that it will equip a production vehicle with V2V technology, but it’s likely that other premium brands will soon follow suit, especially now that the U.S. Department of Transportation has begun the process of writing rules to mandate the technology in the coming years.

Beyond Cruise Control

Barra also announced that a new Cadillac model that has yet to be revealed will be the first car in its lineup equipped with super cruise technology.  Super cruise is a semi-autonomous highway driving mode that combines advanced radar-based adaptive cruise control with upgraded camera-based lane-following capability.  In traffic, the system is able to bring the car to a full stop, automatically restarting as soon as the leading car moves.  GM first demonstrated super cruise to media in 2012 and has continued to refine the system.

In the days before the official opening of the ITS World Congress, Toyota held a separate advanced safety systems seminar where it demonstrated a system very similar to super cruise installed in the Lexus GS 450h.  The system also includes the capability to determine which lane the car is in to provide the driver with alerts for potential hazards, such as traffic merging from the left or exit-only lanes.  GPS doesn’t provide enough precision to determine which lane a vehicle is in, and Toyota engineers declined to provide specifics, but the system almost certainly uses the new higher-fidelity camera that is installed as part of the lane-tracking system.

Driver Still Required

Toyota also announced that this system would be coming to market very soon, but would not be as specific as GM.  During the technology demonstrations at the congress, Honda also demonstrated its own automated highway driving system, although it has not yet announced when the system will reach production.

The key to these systems is that they do not completely replace the driver, but simply reduce the workload during some of the more monotonous aspects of highway driving.  Unlike Google, which is extremely bullish on autonomous vehicles, traditional automakers, which are more familiar with the realities of putting high-technology cars in customers’ hands, are taking a much more cautious approach.

 

Toyota Commits to Active Safety Features

— September 18, 2014

If the world’s largest automaker gets its way, by the end of this decade, we can expect advanced active safety and semi-automated driving features to become as familiar as anti-lock brakes and stability control have in the past 10 years.

During an advanced safety systems seminar near Toyota’s North American technical center in Ann Arbor, Michigan, the automaker challenged its competitors when it committed to offering advanced active safety systems across its lineup by 2017.  Toyota also increased its commitment to advanced safety R&D by extending the initial 5-year mandate of the Collaborative Safety Research Center (CSRC) from 2016 through 2021 and adding $35 million in new funding.

At the same event, Simon Nagata, senior vice president of the Toyota Technical Center, announced an expansion of the scope of the CSRC, which was launched by company president Akio Toyoda in 2011.  Nagata described the program as unique in the industry because “all findings are openly shared in order to benefit people everywhere.”

CSRC research initially focused on three areas: driver distraction, active safety, and helping to protect the most vulnerable traffic populations, including children, teens, and seniors. Automated and connected vehicle technologies are now part of the CSRC scope of work. To date, CSRC has initiated or completed 34 projects with 17 universities and research hospitals.

Join the Crowd

Ford has drawn attention in recent years for offering a full suite of driver assist capabilities, including active park assist, blind spot information, lane departure warning and prevention, and adaptive cruise control on the high-volume Fusion midsize sedan.  Some of these features are even available on the smaller Focus and Escape.  Other manufacturers, including Nissan, Honda, and even Hyundai, have since added some of these features to mainstream products.  Toyota, on the other hand, has largely restricted these technologies to its premium Lexus brand.

“Many of these capabilities will be added to Toyota brand vehicles starting in 2015 and with the goal of becoming the first full-line manufacturer to offer these technologies across the entire lineup by 2017,” said Bill Fay, Toyota group vice president and general manager.  Fay didn’t provide details about exactly which vehicles will get what features.  However, the updated 2015 Camry sedan, announced in April at the New York Auto Show, will offer radar-based adaptive cruise control, blind spot monitoring, cross traffic alert, lane departure alert, and a pre-collision system.

Toyota’s increased emphasis on active safety and automated driving is likely to inspire both the competition and regulators who may well see this as an opportunity to begin mandating the technologies that are building blocks for autonomous vehicles, just as they did previously with stability control and rear cameras.  And it will provoke a wider discussion of how we incorporate automated vehicles into the transportation ecosystem.

 

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