## Eaton Developing Hybrid System for Class-8 Trucks

##### 22 June 2006

Eaton Corporation is developing a parallel-hybrid power system for the heavy-duty (Class 8) commercial vehicle market to deliver both on-road efficiency and idle reduction for significant fuel savings and emissions reductions.

The heavy-duty system will be similar in design and will share many of the same components as Eaton’s medium-duty hybrid electric system built for Class 4-7 vehicles, but will be adapted for Class 8 vehicles with on-highway applications.

Fleets using Eaton’s heavy-duty hybrid system will experience reduced fuel consumption both while driving and when parked. Recent independent test results have shown a 5-7% savings versus a conventional Class 8 vehicle while driving, and a savings of one gallon per hour when parked.

Those savings equate to about $9,500 a truck per year in normal operation, resulting in cost savings for a typical truckload carrier with 1,000 power units to$9.5 million per year.

The idle reduction mode in Eaton’s heavy-duty hybrid system will enable fleets to save fuel, reduce emissions and comply with rapidly expanding local anti-idling laws. The system’s batteries power the heating, air conditioning, and vehicle electrical systems while the engine is off.

When the idle reduction mode is active, engine operation is limited to battery charging, an automatically controlled process that will take approximately five minutes per hour. In the proposed system design, a proprietary feature minimizes engine vibration during start-up and shut-down during the recharge periods, allowing the driver to rest without interruption.

Eaton’s will build its heavy-duty hybrid-electric power system using an automated manual transmission with a parallel-type direct hybrid system, incorporating an electric motor/generator located between the output of an automated clutch and the input to a Fuller UltraShift transmission.

The system will support regenerative braking. When electric torque is blended with engine torque, this recovered and stored energy is used to improve vehicle performance, operate the engine in a more fuel-efficient range for a given speed, or operate with electric power only.

We see an exciting future for hybrid electric vehicles in the heavy-duty market place. We’ve demonstrated our leadership in hybrid power over the last five years for our medium-duty customers, and we’re confident that we can carry that forward with a strong value proposition to our heavy-duty customers.

—Kevin Beaty, manager, Eaton Hybrid Power Systems

Eaton’s heavy-duty hybrid system is currently in the testing and development phases. Eaton is working with truck and engine makers and select fleets to field prototypes for field evaluation. Eaton expects to make available its heavy-duty hybrid power system well before 2010, and could help meet the latest EPA emissions regulations scheduled to be enforced at that time.

Eaton has been working on introducing hybrid power into commercial trucks since 2002 when it was selected as the sole supplier of 18 hybrid electric power systems that were installed in the Fed-Ex Opti-Fleet E700 vehicle through a project sponsored by FedEx Express and advocacy group Environmental Defense.

That same year Eaton was selected, in partnership with International Truck and Engine, to lead the Department of Energy and its National Renewable Energy Laboratories’ Advanced Heavy Hybrid Propulsion System project. Through this project Eaton developed a hybrid electric power train for the class 4-7 market that was integrated onto a United Parcel Service (UPS) urban package delivery vehicle. (Earlier post.)

FedEx is ordering an additional 75 Opti-Fleet E-700 trucks, and UPS is ordering an additional 50 hybrid vans. Eaton has also partnered with International and the Hybrid Truck Users Forum to build hybrid-powered utility trucks, of which 24 have been built and are being deployed in utility fleets throughout the United States. (Earlier post.)

Eaton is also involved in hydraulic hybrid systems for various truck applications and yesterday teamed with the Environmental Protection Agency, UPS, International and the US Army to unveil a hydraulic hybrid diesel vehicle that significantly increases fuel efficiency and decreases emissions. (Earlier post.)

I'd like to see the trucking companies (Peterbilt, PACAR, etc) do more to address aerodynamics of those vehicles as well.

Patrick -

trucking is an industry operating on paper-thin margins defined largely by fuel economy and payload. If there were even small savings to be had by further aerodynamic sculpting (beyond the wind guide above the driver cabin), you can be sure they would be implemented. Just compare US 18-wheeler and European truck designs. The difference is due mostly to the different price of diesel fuel.

Rafael; we don't seem to have much access to European truck design over here. Anything you could forward would be appreciated...

Rafael-

Walmart has implemented various changes to their truck fleet that have improved the aerodynamics of their vehicles (talking about 18 wheelers).

http://www.greencarcongress.com/2005/12/walmart_seeks_t.html

Richard -

example of US 18-wheeler:

http://www.macktrucks.com/default.aspx?pageid=1402

example of European HDV (note the deflector above the driver cabin, some US models have these too now):

http://www.scania.com/products/newtruckrange/cabs/aerodynamics/

example of European MDV (note the slope in bonnet and windscreeen):

http://www.mercedes-benz.de/content/germany/mpc/mpc_germany_website/de/home_mpc/vans/home/products/nya_transportbilar/New_Sprinter.html

example of European bus (note the rounded shape of the vehicle front and the sculpted rear view mirrors):

http://www.mercedes-benz.de/content/germany/mpc/mpc_germany_website/de/home_mpc/buses.html

All in all, aerodynamic optimization is modest compared to LDVs and takes a back seat to the utility of the vehicle, i.e. cargo space and/or payload. It's just a question of cost/benefit optimization. Same goes for hybrid powertrains for commercial vehicles.

The largest challenge to improving fuel ecomony in the U.S Heavy Duty (class 8 - 80,000 lbs GVW) trucking market is to get drivers & fleets to accept aerodynamic vehicles. Most drivers do not "like" the Aero look, they prefer the boxy, Peterbilt 379 and Kenworth W900 with a wide trailer gap. Switching to a Pete 357 or Kenworth T2000 a very small (>18") trailer gap can improve fuel ecomony by 1 MPG. The acute driver shortage prompts smaller fleets to use Truck Model style & features to keep drivers. The rising cost of fuel will hopefully push the industry towards sensible trucks with better economy. A properly configured aero package with the correct geatrain spec can get 7-8 MPG. Most fleets cannot get out of the 6 MPG range.

The largest challenge to improving fuel ecomony in the U.S Heavy Duty (class 8 - 80,000 lbs GVW) trucking market is to get drivers & fleets to accept aerodynamic vehicles. Most drivers do not "like" the Aero look, they prefer the boxy, Peterbilt 379 and Kenworth W900 with a wide trailer gap. Switching to a Pete 357 or Kenworth T2000 a very small (>18") trailer gap can improve fuel ecomony by 1 MPG. The acute driver shortage prompts smaller fleets to use Truck Model style & features to keep drivers. The rising cost of fuel will hopefully push the industry towards sensible trucks with better economy. A properly configured aero package with the correct geatrain spec can get 7-8 MPG. Most fleets cannot get out of the 6 MPG range.

Truck stop overnite idling is a big consumer of fuel. Implementation of external power interface, or a small clean secondary engine would make a big difference in fuel and \$ spent. Not to mention air quality and quiet. Parts of the hybrid concept described above may enable doing away with the small engine or external power.

I suspect the real driver for this project is not customer demand for greater fuel efficiency so much as a need to downsize to meet the new extremely strict diesel emissions regs.

Regular truck = large engine (10-12L displacement), smoke when you step on the gas.

Hybrid truck = mid-size engine (5-6L displacement) + beefy electric motors, potentially even near front wheels (controller can provide power steering support). Small/no smoke puff when accelerating.

Also, simply less NOx when going uphill with battery support, recuperation on the downhill ride (electric retarder). Downside: you need a lot of batteries, which take away from your payload capacity.

Given the cost of a Class 8 truck, I don't see fleets rushing to replace what they already have.
There'll have to be some Carrot & Stick program at state or federal level.

The drag at the tail is much greater than the drag at the nose. Just look at blimps as evidence. If regs could be changed to allow a tapered extension to trailers then significant fuel savings could be had at little costs.

Tom -

for substantial reductions in aerodynamic drag at the tail end, you'd have to approximate an eleongated teardrop shape. Failing that, a vortex-shedding cut-off is actually better than a half-way house. Some improvement may be possible without changing total vehicle length, but not all that much.

More significant opportunities are related to airflow under the vehicle. But as I pointed out before, commercial vehicles are built first and foremost for payload. The cost of diesel would have to be quite high before payload weight would be sacrificed for additional aerodynamic cowlings.

The reason they cant add rear cowlings is of course rather obvious. The truck itself is only in the front the shipping container is just a box and wont chaqnge one micron. And the only other bit is the wheeled platform the container rides on.

The only way to improve things drasticaly would be to allow MUCH larger trucks that carried the containers INSIDE a cargo hold... but our roads arnt big enough for that scale.

The regenerative braking seems like an interesting partial solution to stupid small towns' most annoying trait: the banning of jake brakes. Many little mountain towns prohibit the use of an engine brake because of the noise (never mind the 80,000 lb of truck and trailer trying to slow down with drum brakes). Could the regenerative braking system be used to slow the truck in a way similiar to a jake? Also, could the trailer be fitted with it's own baterries and electric motor's to provide boost and additional regeneration?

Please ignore my spelling and grammar in my above post. I've just woken up about an hour ago after working too long and hard on some hydraulics all week. :)

John -

recuperative retardation on downhill descents is a major motivation for hybrid HDVs. It may not be feasible or economical to install batteries large enough to handle really long descents but a hybrid arrangement would reduce the thermal load on the retarder. This quiet component is found in HDV but not in LDV drivetrains, perhaps you are familiar with it:

http://en.wikipedia.org/wiki/Retarder_%28mechanical_engineering%29
http://www.voithturbo.com/533863.htm

As for electric motors and batteries in a trailer, in principle that would be possible. However, you'd have to be careful about torque levels. Go too far and you could end up destabilizing the vehicle dynamics.

On a more general point, electric motors can drive axles that are not connected to the mechanical drivetrain. This would be beneficial in several respects: greater traction for safety on wet roads, reduced smoke puff and tire noise during acceleration, increased tire life expectancy (and hence, safety).

For those discussing aero of heavy trucks. For current model tractors with a full aero package the distribution of aerodynamic forces on the tractor and trailer is approx 30% tractor and 70% trailer. The 70% trailer drag is divided between ; 20% front face (gap), 25% rear base and 25% undercarriage. Recognizing operational and maintenance requirements the drag of a tractor could be reduced an additional 25% whereas the drag of the trailer can be reduced 35%.

http://www.airtab.com/

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