Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – With indicator or control of power plant
Reexamination Certificate
1999-10-29
2001-08-07
Argenbright, Tony M. (Department: 3747)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
With indicator or control of power plant
C123S406600
Reexamination Certificate
active
06272428
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an apparatus and method for a capacitive discharge digital ignition system for controlling combustion engine ignition, the system including a controller, a programmer, a high voltage unit, and means to program engine ignition timing values across the engine speed band, as well as other function parameters.
BACKGROUND
It is increasingly the case that cars and other vehicles with combustion engines employ digital rather than conventional analog ignition systems. A digital ignition system is preferable to an analog ignition system since a digital ignition system is generally not affected by temperature and humidity and, thus, provides more accurate and consistent engine performance. However, digital ignition systems heretofore, while accurate, have been of limited flexibility in terms of programmability and robustness. Such digital ignition systems have not allowed the user to take full advantage of a given engine's specific characteristics. Such digital ignition systems have not allowed the user to remotely program ignition parameters in a substantially real-time manner to optimize performance for the circumstances. These are significant disadvantages.
Additionally, each engine may have its own slightly different characteristics in terms of dimensions, composition, weight, flow characteristics, and so on. In layman's terms, each manufactured engine has its own idiosyncrasies. Existing digital ignition systems have not permitted the user to truly optimize performance because certain such idiosyncrasies are not accounted for. In a highly competitive environment, such as racing, this is a significant disadvantage because small improvements in performance can mean the difference in winning a race.
In high performance combustion engine applications, such as drag racing, a capacitive discharge ignition system is often preferred because a capacitive discharge ignition system is fast and efficient at providing energy for creating sparks, especially at high speeds. A capacitive discharge ignition system uses a storage, or “bathtub,” capacitor to hold energy until the correct time to make the spark. The capacitor is connected to an ignition coil of the engine through a switch such that, to generate a spark, the switch is activated to dump the charge from the capacitor to a primary side of the ignition coil in less than {fraction (1/10)}
th
of a millionth of a second. The voltage applied to the ignition coil as a result of the capacitor discharge is then stepped up by the turns ratio of the ignition coil and applied to spark plugs of the engine for igniting fuel within combustion chambers of the engine.
A significant benefit of this approach is that the capacitor can be charged extremely fast and can hold energy for extended periods with almost no loss or leakage. It can then can release the energy to the ignition coil very quickly. Thus, a capacitive discharge ignition system provides an extremely fast and efficient method of storing and distributing energy to create sparks in an engine, with little or no drop-off in engine performance at high speeds.
However, as is often the case in engineering tradeoffs, there are disadvantages that flow from the use of capacitive discharge ignition systems. For example, the quicker, hotter sparks of a capacitive discharge ignition system results in a shorter duration for each spark, which can disrupt engine performance at low speeds. At high engine speeds, a shorter duration spark is not a problem since the spark is supposed to occur very quickly. But at low engine speeds, the shorter duration sparks can result in poor performance because cylinder pressures and temperatures are low and air/fuel mixtures can be less than optimal. This is a significant disadvantage. There are other challenges presented to the use of a digital ignition system using a capacitive discharge mechanism.
A capacitive discharge engine will preferably also include an engine speed, or “rev limiter” feature to protect the engine from dangerous high speeds, or “over-revving,” where the engine could be damaged or even explode. A rev limiter feature turns off the spark to individual cylinders of the engine when engine speed exceeds a preset maximum level. Thus, the engine is purposely caused to misfire so that the engine speed is brought back down to the preset maximum level. Existing implementations of rev limiters have not provided optimum flexibility and programmability to allow the user to readily optimize rev limiting to circumstances. This is a significant drawback.
Another difficulty often encountered in high-performance applications, such as racing, is the tendency of the user to provide too much torque to the wheels upon launch. Often the wheels lose traction and precious time is lost as a result. This can be the difference between winning and losing a race. This is a significant drawback.
Other problems and drawbacks also exist.
SUMMARY OF THE INVENTION
Accordingly, one object of the present invention is to overcome one or more of the aforementioned and other limitations of existing systems and methods for digital ignition systems.
It is another object to provide a capacitive discharge digital ignition system with a controller and programmer for changing values stored in the controller for substantially immediate effect.
It is another object to provide such a system whereby the programmer can be used to program engine timing curves, rev limiters, retard values, engine speed and/or time activated switches, and other such engine functions, in order to optimize performance for an engine's characteristics and/or for particular applications, such as racing.
It is a further object to provide such a system and method where stored timing curve data is provided on a cylinder-specific basis, thereby optimizing performance.
It is a further object to provide such a system and method where cylinder-specific timing curve data is dynamically adapted based on control loop data to effectively self-tune an engine.
It is another object of the present invention to provide satisfactory performance over the engine speed band using the capacitive discharge ignition in a manner that considers available electrical energy and charging or discharge times to tailor multiple sparking or “restrikes” at low engine speeds.
It is yet another object of the invention to provide a so-called launch control function which retards engine timing for a period after launch to reduce traction loss.
Accordingly, the present disclosure relates, in general, to a system for controlling ignition timing in an internal combustion engine. The digital ignition system of the present invention utilizes a controller, including a central processor unit and memory, for controlling system functions such as restrikes, rev limiters, engine speed and/or timing activated switches, spark duration, and ignition timing. Furthermore, the features of the present ignition system, such as restrikes, rev limiters, engine speed and/or timing activated switches, spark timing retards and timing curves, will preferably be provided in an integrated package such that add-on boxes and other additional components are not necessary and do not have to be added to the ignition system once installed in a vehicle. Furthermore, the features are programmable, including programmability of ignition timing curves on a per-cylinder basis to optimize performance to an engine's particular characteristics.
The preferred capacitive discharge digital ignition system includes means for instantaneously, and remotely, programming system functions values. By instantaneously and remotely, it is meant that the ignition system should allow a user to be seated in a driver's compartment of a vehicle incorporating the ignition system, while the vehicle is positioned at a starting line at the beginning of a race, with the engine either running or turned off, to instantaneously change system parameters so as to optimize performance for the setting.
Accordingly, the digital ignition system disclose
Heath David
Mackie Ronald D.
Argenbright Tony M.
Holley Performance Products, Inc.
Hunton & Williams
Vo Hieu T.
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