Current state-of-the-art problems stem from physical preparation of fuel before it burns. More precise fuel preparation will burn less fuel more cleanly. How can this be done?
GPDT’s magnetostrictive actuator technology offers a unique combination of three key characteristics never before available for a durable diesel fuel injector:
Indestructibility is an inherent, quantum mechanical, atomic effect and therefore cannot be patented. However, discovering how to extract and use the high force and speed sourced by this effect is protected by patents and proven by test.
- Magnetostriction is indestructible -- the actuator is durable.
- High force is available at any time and point in range.
- High speed is available at any time and point in range.
Here is how GPDT employs this responsive control to more precisely prepare fuel:
- Needle lift is now always proportional to electrical current magnitude. This means that the needle can be stopped anywhere in its range at any time, in effect creating a variable orifice to control the rate at which fuel can flow out of the injector.
- Very importantly, needle speed is no longer a result of the presence or absence of fuel pressure as in the traditional injector but is now always proportional to the time rate at which that current changes.
In particular, needle speed is no longer limited by the finite time it takes for a pressure wave to propagate through the fuel between the servo valve and the needle.
- Heat can be added inside the engine in such a way that less fuel is wasted.
- Needle speed can be so fast that small amounts of fuel (fuel dots) can be added at certain points in time, which is known to reduce the generation of emissions.
- The precise opening and closing control permit the needle to close with “near-zero” contact velocity and no bounce. The benefit of this is that fuel pressure can be raised to further reduce emissions.
- Time delays between events are eliminated.
How To Use This Capability
It has long been known how best to physically prepare fuel for optimal combustion in a diesel engine. Below are quotes from a small sample of the prior art. In sum, the requirements are for the fuel injector to be fast and to continuously control each injection event. Emphasis added.
U.S. patent 2,721,100 proposed an injector using a magnetostrictive actuator to directly operate its needle at 20,000 to 40,000 hertz.
U.S. patent 2,977,941 proposed a method of burning multiple fuels in a compression-ignition engine.
- Column 1, lines 28-32: “... causing the fuel spray to be injected in intermittent bursts, somewhat in the fashion of a string of sausages. This mode of ‘pulsed’ fuel injection conditions the fuel to in some way improve combustion.”
- Column 4, lines 46-51: “The described gradual increase in the rate of fuel injection is provided to give time for combustion to be established before a large fuel charge has been permitted to accumulate in the cylinder. This is especially to be desired with diesel (auto-ignition) engines, as is known in the art.”
- Column 5, lines 22-27: “... so as to assure that each injected fuel charge will be broken into a very large number of individual 'bursts.' Not only is atomization thus made more complete, but fuel accumulation is prevented, and diesel type combustion of unusually smooth characteristics can thus be accomplished.”
U.S. patent 4,022,166 proposed an injector using a piezoelectric actuator to directly operate its needle.
- Column 1, lines 25-29. “It has long been highly desirable to have a compression ignition engine which will utilize without alteration or change of parts the full range of liquid fuels that are readily available for internal combustion engines of both the spark and compression ignition types.”
- Column 6, lines 14-22. “The low rate of pressure rise of a 2 kg./cm.² per degree of crank angle reduces the structure-borne sound of the combustion noise below the noise level of the other noise producing parts, such as valves, piston, gears, pumps and cooling fan. The desirable insensitivity to the cetane number of the fuel makes it possible to use without difficulty or loss of performance any and all liquid hydrocarbons having a very low cetane number, including gasoline having high octane numbers.”
- Column 8, lines 16-23. “The fuel is not conventionally ignited in a noisy quick explosion but rather burns with a quiet progressive consumption in relation to piston movement to provide a much desired sustained pressure for an important effective length of time when the pressure is most effective. For the reasons noted the quietness and efficiency of the engine will be appreciated because of the controlled duration of the burning and pressure build-up...”
U.S. patent 5,845,852 proposed an injector using a piezoelectric actuator to directly operate its needle.
- Column 4, lines 57-68. "Because of the rapid response of the needle, actual tests showed that the duration of injections could be controlled within thirty microseconds without ragged spray initiation or termination dribble, making possible carefully controlled multiple and discreet injections into an engine cylinder as the piston approaches top dead center. The latter characteristic has shown to be of particular advantage in diesel engines where the released heat and pressure rise in the cylinder can be controlled by the rate and number of injections to effect more complete combustion of the fuel at lower peak temperatures and pressure."
U.S. patent 6,499,467 discusses needle impact and getting small quantities by slowing the needle.
- Column 1, lines 51-56. "...the motive force for moving the injector check is provided by the pressurized fuel itself rather than a directly controllable motive power source. Accordingly, the degree of controllability required to desirably reduce particulate and gaseous emissions in accordance with regulatory agency standards is minimal."
- Column 5, lines 35-38. "Further, the controllability of the injector 18 is severely limited, thereby limiting the opportunity to reduce gaseous and particulate emissions through control thereof."
- Column 9, lines 16-18. "...by presqueezing the solid state actuator 80 the preload assembly maximizes the stiffness and thereby the performance of the actuator 80."
The remedy has been long known. It now can be implemented.
- Column 1, lines 53-59. “It is well known that the level of emissions generated by the diesel fuel combustion process can be reduced by decreasing the volume of fuel injected during the initial stage of an injection event and decreasing the time required for valve closing. It is also desirable to limit the impact velocity of the needle valve against its seat upon closing.”
- Column 3, lines 6-8. “It is a still further object of the present invention to provide a servo-controlled injector capable of preventing needle valve element bounce in the open position.”
- Column 8, lines 7-11. “...needle valve biasing feature 20 of the present invention enables a significantly higher needle closing velocity while providing a hydraulic damper near the end of the closing event to prevent violation of seat impact velocity constraints.”
- Column 9, lines 4-10. “Typically, the conventional needle is designed to severely limit the allowable closing velocity in the earlier phase of needle closing to prevent this high impact velocity. If the allowable closing velocity in the earlier phase of needle closing were not limited, the needle would likely bounce from its valve seat and experience excessive wear or failure over time.”
- Column 9, lines 17-22. “The needle valve biasing feature 20 of the present invention slows down the opening of the needle valve element ... which creates a greater amount of time to accurately deliver small fuel quantities.”