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EDI partners with Greenkraft for parallel-series multi-mode Class-4 CNG-PHEV truck; CEC funding

Greenkraft truck. Click to enlarge.

Efficient Drivetrains, Inc. (EDI), a producer of plug-in hybrid electric vehicle (PHEV) and continuously variable transmission (CVT) solutions (earlier post), is partnering with Greenkraft, CALSTART, and the California Energy Commission (CEC) to develop a Class-4 vehicle that combines the benefits of compressed natural gas (CNG) and PHEV technology. EDI was co-founded by Professor Andy Frank from UC Davis—a key figure in the development of the PHEV concept and technology—in 2006.

The effort combines EDI’s intelligent multi-mode PHEV powertrain (EDI-Drive) with Greenkraft’s CNG-powered 14,500-pound, Class-4 medium-duty truck, which is equipped with a 6.0L GM engine. EDI’s solution can improve the fuel economy of a conventional CNG-powered medium-duty truck by more than 40%, the company said.

Elements of the EDI-Drive. Click to enlarge.

EDI’s announcement came simultaneously with a grant approval for the combined partnership by the California Energy Commission of funding from its Energy Research and Development Division. On 28 February 2014, the CEC’s Public Interest Energy Research (PIER) Natural Gas Program released a Program Opportunity Notice (PON-13-506) entitled “Natural Gas Engine-Hybrid Electric Research and Development.” The purpose of this solicitation was to accelerate research and development of advanced natural gas engine- hybrid concepts for medium- and heavy-duty vehicles. The solicitation announced that $2,700,000 in funding was available for a minimum award size of $500,000 and a maximum award size of $900,000 per project. EDI is receiving a unanimously approved $900,000 grant.

The proposed EDI research includes design, optimization manufacturing, testing/validation, and demonstration of the PHEV powertrain (EDI Drive) and battery pack with 40 miles of all-electric range (AER).

One of the goals of the project is to achieve approximately 29% thermal efficiency improvements compared to the baseline CNG-powered Greenkraft truck, and effectively triple the miles per gasoline gallon equivalent (GGE) of the baseline CNG-powered Greenkraft truck from approximately 9 miles per GGE to 27.

The project will also determine which duty cycles and applications for medium-duty CNG-PHEV systems promise the greatest benefits—including the possible elimination of the use of CNG and achieving 100% all-electric operations in certain cycles.

The project will demonstrate the integrated, full-performance, and range-extended CNG-PHEV on the road, both in operations at Greenkraft and in ride-and-drive demonstrations with a variety of regional fleets, including Ryder, Penske, and FOX Transportation.

EDI-Drive. The EDI-Drive system automatically adapts its functions so it can operate as either a pure electric vehicle (EV) for trips around the neighborhood, or as a series hybrid, suited for stop-and-go city traffic conditions, or as an efficient parallel hybrid that is ideal for the highway. It also features an EV+ Mode for hill climbing and added acceleration.

The inline form factor allows the drivetrain to integrate into any light-, medium- or heavy-duty vehicle design. One major innovation is EDI-Drive’s ability to temporarily combine the generator (EM1) and traction (EM2) motors to provide the equivalent of two traction motors, which can provide greater EV torque and efficiency when needed, due to this multi-motor configuration.

The control software monitors the drive cycle and available energy and switches seamlessly among the four modes as required maximizing electric range and minimizing fuel consumption and greenhouse gas (GHG) emissions.

Because it operates without an oil sump, the EDI Drive is the only “dry” transmission design in existence, delivering more efficiency and greater performance at a lower cost than other two-motor systems.

To accommodate charging throughout the day, the CNG-PHEV will also be equipped with an onboard electrical charging system that includes adapter plugs and an extension cord, helping to ensure that the CNG-PHEV can charge at any standard industrial outlet. In addition, to help ensure compatibility with circuitry at remote locations, the CNG-PHEV will also be equipped with an intelligent charging system (patent pending) that can determine the power capability of any standard plug automatically.

In addition to developing drivetrain solutions using all types of transmission options (AT, AMT, MT) EDI has also developed its own CVT technology which can provide significant performance improvements for hybrid, plug-in hybrid, electric, and even conventional vehicles.

EDI’s CVTs are targeted at both light- and medium-duty applications for either front or rear wheel drive and can support requirements for higher torque ranges and greater levels of efficiency than any other CVT transmissions available in the market today, the company claims. EDI’s CVT technology includes designs for high efficiency mechanical CVTs, CVT controls, and for the integration of CVTs into a variety of drivetrain and industrial applications.



A proven way to extend the use of fossil and bio fuels while reducing GHG.

Why not do it.


This is a good way to extend the range of a CNG truck, a given sized tank could get you 100 mile range, now perhaps 140 mile range with hybrid drive. Dr. Frank pioneered hybrids back in the 1980s, he has great engineering ability.

I would suggest that his company get some market input. FIRST find out if anyone wants and needs this kind of truck, or what kind of truck they really want and need, THEN start to design it. Too often engineers are prone to "build it and they will come" thinking, which today may not have a good chance of success.

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