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The Future Of Cummins, Ford and GM Diesels

We explore diesel technology from The Big Three and the U.S. Department of Energy expected to arrive by 2015.

Text By Jason Thompson, Photography by Courtesy of the Department Of Energy

The primary mission of the U.S. Department of Energy's Vehicle Technologies Program is to reduce the 13.7 million barrels of petroleum our country burns each day for our transportation needs. Why is that important? Our country's economic, political, and military strength is directly connected to our energy independence, which would be at a great advantage if our vehicles got more miles per gallon.

One of the Department of Energy's methods is to help the manufacturers increase the thermal efficiency (work out, divided by fuel in) of diesel engines from around 30 percent (found in today's vehicles) to 50 percent by 2015, and 55 percent by 2018. Some of these energy-conserving technologies are gradual changes to traditional designs, while others are more drastic. Today, gasoline engines (at 25 percent thermal efficiency) are the main drivers of the U.S. transportation system, and a switch to diesel in our consumer sector would be the easiest way to cut back on our use of foreign oil.

Cummins
Cummins' goal was to improve the thermal efficiency of the 15.0L ISX and 6.7L ISB while still meeting the EPA's 2010 emissions standards and being B20 compatible. Oak Ridge National Laboratory, Purdue University, and BP helped with fuel sensing technology that virtually offsets the fuel consumption penalty of biodiesel. The team also found that a fuel blend of diesel and gasoline is desirable for advanced ignition strategies such as premixed controlled compression ignition (PCCI). Possible additions to future 6.7L diesel engines include: compound turbochargers with a high-pressure variable-geometry (VGT) exhaust housing, a variable-displacement oil lubrication pump, and piezo injectors capable of 31,900 psi and seven injection events. The heavy-duty Cummins ISX 15.0L engine is projected to receive variable valve actuation, an injection system capable of 37,700 psi, and thermal management insulation. Chrysler and PACCAR were also involved with vehicle packaging and demonstration models. Cummins spent $4.3 million (matched by the DOE) on its waste heat recovery program (for an in-depth look check out "Cummins Steam Engine," Oct. '08) and $2.4 million (matched by the DOE) on the advanced high-efficiency clean-combustion program.

Ford
Ford put $1.5 million (matched by the DOE) into research focusing on advanced turbo systems and sophisticated injection strategies for its future diesel engines. According to Ford, 20 to 40 percent of the engine's power is used to drive the turbocharger in today's boost-dependent engines, so efficiency gains in this area would have a high payoff. In this particular study (in which Wayne State University was a partner), Ford looked at how heavily cooled EGR negatively affects turbo efficiency. Unfortunately, Ford summarized that challenging a relatively matured technology turns out to be much more difficult than anticipated. The improvements to the turbo system only netted a 2- to 3-percent increase in fuel economy. On the bright side, this peer review, dated June 10, 2010, announces that the innovations gleaned from their research efforts will go into a small, turbocharged, light-duty diesel of less than 5.0L. Diesel Power speculates that one of the reasons for the 1/2-ton diesel delay was because these engines were testbeds for the different manufacturers trying out their most advanced technologies.

GM
General Motors is putting $6.25 million (matched by the DOE) into research specifically exploring variable-valve actuation, two-stage-series sequential turbocharging, and advanced ignition strategies in its 4.5L diesel. GM's partners in this project (that began back in 2005) include FEV, TEAM Corporation, Mechadyne International, Eaton, and Mitsubishi. GM's development of high-efficiency, clean-combustion diesel engines began with a single-cylinder engine that featured fully flexible variable-valve actuation and the 4.5L V-8 with a simple variable-valve actuation mechanism. The difference is the former does not rely on a fixed mechanical camshaft to open and close the valves; instead, an electro-hydraulic valve has complete control over valve lift and timing. The fully flexible valved engine achieved Tier 2 Bin 5 NOx engine-out targets without aftertreatment, but it's a technology not quite ready for production. The new valvetrain on the 4.5L is called Switching Roller Finger Followers and includes a concentric intake camshaft and phaser, and a two-profile exhaust lobe. Benefits of this new system include internal EGR (in which exhaust gas is kept in the cylinder), late intake valve closing (in which the dynamic compression ratio can be changed from 16:1 to 14.75:1), and the ability to vary the lift of the exhaust valve. These abilities equal cleaner emissions and more fuel economy, since PCCI ignition strategies can be achieved under wider operating ranges.

What Makes the World Go Round?
The world burns 85.90 million barrels of underground petroleum per day, which adds 24 billion tons of carbon above ground per year (scientists say oceans absorb around 50 percent of this and are getting more acidic as a result, which greatly affects the food chain).

Heavy-duty trucks use 20 percent of the fuel consumed in the United States. The DOE's Super- Truck Initiative has a goal to demonstrate a 50-percent improvement in freight efficiency by 2015. Improvements will come from better aerodynamics, increased combustion efficiency, turbo compounding and waste heat recovery, lessened rolling resistance, energy recovery from braking, reduced friction in drivetrain, and electrically driven accessories.

SOURCES
U.S. Department Of Energy
1000 Independence Ave., SW
Washington
DC  20585
202-586-4403
www.fueleconomy.gov
U.S. Department of Transportation
800-832-5660
http://www.fmcsa.dot.gov/registr
ation-licensing/cdl/cdl.htm
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By Jason Thompson
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