Great Plains Diesel Technologies
707 East Lincoln Way
Ames, Iowa 50010 USA
Office: 515.233.2962
Fax: 515.232.2240

Explore The Technology

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"Best Improvement in a Durable Actuator Since 1913"

Our simplified solution is to treat the problem at its source – in the cylinder – by developing a durable, continuously- controllable, or "programmable," direct-acting diesel fuel injector. That the solenoid-operated injector has been highly refined since at least 1913 (Gaff's patent 1,059,604) is testament not only to its durability on a cylinder head but also to the previous lack of any suitable replacement.

The Cost of Fuel

The theoretical foundation for a heat engine guides our fuel injector design.

  • Heat not used to expand matter is wasted. Heat that leaves through the radiator or exhaust is lost fuel economy.

  • Maximum fuel economy is governed by the maximum temperature due to the engine compression ratio.

  • Add heat at constant temperature, where all of the heat is then converted into work. Ideally, as the gas volume expands by piston motion, fuel is injected at a rate such that the added heat does not raise the gas temperature. The rate of fuel flow must continuously vary throughout each injection event.

  • Electro-Technology Comparison

    Select an electro-technology that enables adding heat at constant temperature.

    The rare-earth alloy commercially available as "terfenol-d" possesses characteristics that are key to a durable, continuously-controllable diesel fuel injector.

  • It's Young's modulus permits it to store a lot of mechanical energy, necessary for speed. It can store enough energy to directly operate the valve element. In other words, unlike solenoids and piezo, it has no need to wait for re-directed pressure to operate the valve element.

  • The magnetostrictive effect cannot be destroyed by voltage, current, stress, or strain. It diminishes with temperature, but there is no permanent degradation. This indestructible effect originates in the quantum mechanical distortion of the non-bonding 4f electron cloud of the terbium atom. In its standard composition, terfenol-d will display performance reduction at the extremes of the temperature operating range expected for a standard production vehicle in use all throughout the world. To accommodate this known issue requires slightly adjusting the constituent proportions of the alloy mixture itself, allowing the temperature operating range of the terfenol-d to fall into the desired range, while still maintaining all of the attractive properties of the standard composition. This re-formulation is done via application of U.S. Patent 6,758,408, authored by Perry Czimmek. For simplicity, our in-house testing used the readily available standard composition.

  • Terfenol-d is known to withstand billions of expansion cycles without evidence of fatigue or performance degradation.

  • Durable, Continuously-Controllable Actuator Design

    A number of properties of terfenol-d naturally match its employment in an actuator for a durable, continuously-controllable fuel injector.


  • Mechanical expansion output is an analog scale of electrical current input.

  • The time rate of change of mechanical expansion is an analog scale of the time rate of change of electrical current input.

  • Fuel pressure can be used to highly compress the terfenol-d rod. This speeds up the injector by A) storing all the mechanical energy needed to operate the valve element directly, eliminating the time delays of indirect operation as commonly done now and B) reduces the accelerated mass of the rod itself.

  • Using fuel pressure eliminates the need for a preload spring. A spring that can apply the needed preload in the allowable space would be difficult to incorporate and slow down the injector because part of its mass would be accelerated.

  • The high preload lowers the magnetic permeability of the rod. This reduces the voltage required to effect a time rate of change of current. Or, for the same voltage, lowered inductance permits a faster time rate of change of the current.

  • The terfenol-d rod is surrounded by a coil of wire with few turns. Inductance is reduced by the square of the reduction in the number of turns, again reducing voltage.

  • This level of speed and control permits, for example, fast and closely spaced pilots, a fast initial boot, a slower opening to full open, fast closure with near-zero contact velocity, and fast post-injection pulses.


  • The actuator expands with current of either polarity. Polarity need not be observed.

  • The actuator is de-energized most of the time. When energized, it can employ a high magnetic field for even faster operation because the dissipated heat can take longer to be removed.

  • End caps help toughen the actuator against mechanical abuse.

  • Chemically, terfenol-d alloy is inert to non-ionic hydrocarbons. Temperature conditioning can be performed by direct contact with diesel itself, if needed.

  • A hydromechanical section matched to our actuator technology permits adding heat at constant temperature. This level of control, plus very high speed as needed, is now available.


    • Society of Automotive Engineers paper 2007-01-4113 – Possible Very High Speed Rate Shaping Fuel Injector 
    • Society of Automotive Engineers paper 2011-01-0381 – Programmable Diesel Injector Transducer Test Results


    • United States Patent 7,255,290 – Very High Speed Rate Shaping Fuel Injector 
    • United States Patent 8,113,179 – Programmable Diesel Fuel Injector
    • United States Patent 8,418,676 – Programmable Diesel Fuel Injector
    • United States Patent 8,683,982 – Programmable Diesel Fuel Injector
    • United States Patent 9,385,300 – Magnetostrictive Actuator


    • WIPO application PCT/US2011/47253 and Japanese Application 2013-524203 – “Programmable Diesel Fuel Injector” 
    • WIPO application PCT/US2014/15130 – "Magnetostrictive Actuator"
    • US Application 61/918,090 / WIPO application PCT/US2014/071532 – “Diesel Fuel Pressure Detection by Fast Magnetostrictive Actuator”
    • US Application 62/184,115 – “Fuel Injection Rate Modulation by Fast Magnetostrictive Actuator”
    • US Application 15/001,845 – “Fuel Injection Rate Modulation by Magnetostrictive Actuator and Fluidomechanical Coupler”

    Great Plains Magnetostrictive Fuel Injector
    Prototype Test Unit - Scout 1

    Magnetostrictive Transducer

    Spool Valve - Closed Position (Yellow Fuel Passages are Blocked)

    Spool Valve - Open Position (Yellow Fuel Passages are Unblocked)