Internal-combustion engines – High tension ignition system – Using capacitive storage and discharge for spark energy
Reexamination Certificate
1999-04-13
2001-09-04
Yuen, Henry C. (Department: 3747)
Internal-combustion engines
High tension ignition system
Using capacitive storage and discharge for spark energy
C123S644000, C315S212000
Reexamination Certificate
active
06283103
ABSTRACT:
TECHNICAL FIELD
The present invention relates generally to ignitions systems such as used with internal combustion engines, and more particularly, to control of spark duration in such ignitions systems.
BACKGROUND OF THE INVENTION
Capacitance discharge (CD) ignition systems are widely used in internal combustion engines, such as in automotive and industrial applications, to provide energy to the engine spark plugs. The construction and operation of conventional capacitance discharge systems is well known, and is discussed only briefly herein for an understanding and appreciation of the present invention.
A conventional capacitance discharge ignition system typically includes sensors such as variable reluctance sensors that provide signals indicative of crankshaft position relative to top dead center (TDC) of the #1 cylinder and engine speed, an electric power source, means to convert the supply voltage from the power source to a relatively high voltage, a capacitor to store energy from the power source, means to control the voltage on the energy storage capacitor, and timing means to process information from the sensors to determine when the stored energy should be discharged into an ignition coil for delivery to a spark plug.
Conventional capacitance discharge ignition systems are designed to deliver a fixed amount of energy to each spark plug to achieve a spark duration that will ignite the air/fuel mixture in the engine cylinder and sustain the flame for the desired combustion. However, it is well known that spark plug electrodes erode over a period of time, and that the energy needed for a desired spark duration increases as the spark plug erodes. Therefore, the energy delivered to the plugs in conventional ignition systems is set at a relatively high level to ensure that there is sufficient spark duration available to ignite the air/fuel mixture in the cylinder as the spark plug electrodes erodes within pre-defined limits. Unfortunately, delivering energy at a level that is higher than necessary to achieve the desired spark duration for the desired combustion has the effect of accelerating the spark plug erosion, and thus reducing the useful life of the spark plugs.
Another consideration in establishing the operating parameters of conventional ignition systems is the fact that the voltage required to ionize the fuel/air mixture between the electrodes of a spark plug changes as fuel/air mixture changes. As a result, conventional ignition systems are set to deliver excess energy to the spark plugs for anticipated worst-case operating conditions. This results in excessive spark plug erosion at operating conditions less than worst-case, further reducing the useful life of the spark plugs.
The consequences and costs associated with engine down-time to replace worn spark plugs, and the costs associated with the inefficiencies of operating spark plugs at less than the desired or optimal conditions is of particular concern in connection with engines that are utilized in industrial-type applications where the engines may be operating continuously for long periods of time. In fact, in many instances, the engines are intended to operate continuously except for repair-time. In addition to the fact that continuous operation logs substantial hours of operation relatively quickly, as compared with, for example, normal automotive uses, the useful life of spark plugs in some industrial engines are in the neighborhood of only hundreds of hours. In such instances, the losses and costs associated with operating the engine with a conventional ignition system adapted to provide excess energy to the spark plugs are quite substantial.
SUMMARY OF THE INVENTION
The general aim of the present invention is to increase the useful life of spark plugs in an ignition system by providing means for delivering sufficient, but not excess, energy to insure sufficient spark duration for proper ignition of the fuel/air mixture.
A detailed objective is to achieve the foregoing by providing means to measure and/or compute the actual spark duration on a per spark plug basis, and means for modulating the energy delivered to each spark plug independently so as to achieve the desired spark duration. With such an arrangement, an ignition system according to present invention substantially reduces spark plug erosion and the inefficiencies associated with operating an engine at less than optimal conditions, thus, extending the useful life of the spark plugs in the ignition system, and reducing the costs and engine downtime associated with frequent replacement of the plugs.
Another objective is to optionally provide a warning when the desired spark duration cannot be achieved due to excessive spark plug erosion. This will alert an operator that a specific spark plug has reached the end of it's useful life.
These and other objectives and advantages of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.
Briefly, the ignition system of the present invention includes means to determine the spark duration of each of the spark plugs as they fire, and means such as a PI or PID controller to modulate the amount of energy delivered to the energy storage element that supplies energy to the primary winding of the ignition coil, and thus modulates the energy delivered to the spark plugs, as a function of the difference between the desired spark duration and the measured spark duration. In the preferred embodiment, the ignition system also includes a spark duration setpoint adjustment programmable by the operator of the engine, and means to display and/or transmit the amount of energy required to sustain the desired spark duration for warning and diagnostic purposes.
In the preferred embodiment, the ignition system includes a microprocessor that is programmed to operate in a closed-loop mode of operation, to receive the system inputs including a spark duration setpoint signal and a signal that is indicative of the spark duration, to process the information, and to then provide output control signals to adjust the spark duration toward the desired duration.
REFERENCES:
patent: 3906919 (1975-09-01), Asik
patent: 4022177 (1977-05-01), Canup
patent: 4149508 (1979-04-01), Kirk et al.
patent: 4231348 (1980-11-01), Schiele
patent: 4406273 (1983-09-01), Yoshinaga
patent: 4414954 (1983-11-01), Canup
patent: 4631451 (1986-12-01), Anderson
patent: 4913123 (1990-04-01), DeBiasi et al.
patent: 5054461 (1991-10-01), Deutsch et al.
patent: 5056496 (1991-10-01), Morino
patent: 5060623 (1991-10-01), McCoy
patent: 5208540 (1993-05-01), Hoeflich
patent: 5334938 (1994-08-01), Kugler
patent: 5337717 (1994-08-01), Scheel
Gimie Mahmoud
Leydig , Voit & Mayer, Ltd.
Woodward Governor Company
Yuen Henry C.
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