Electronic governor for a gasoline engine

Details Electronic governor for a gasoline engine Electronic governor for a gasoline engine

2001-08-14

2003-06-10

Yuen, Henry C. (Department: 3747)

Internal-combustion engines

Engine speed regulator

Engine speed reduction by partial or complete omission of...

C123S1490FA, C123S605000, C123S626000, C123S406570, C123S406590

Reexamination Certificate

active

06575134

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to an ignition system for a gasoline engine. More particularly, but not by way of limitation, the present invention relates to a capacitive discharge ignition system with integral over-speed governor for a gasoline engine.
2. Background
Electronic ignition systems are well known in the art. In particular, capacitive discharge ignition systems have become popular on gasoline engines ranging from a few horsepower up to engines of hundred, or even thousands, of horsepower. Generally speaking, in a capacitive discharge ignition system, electrical energy is first stored in a capacitor. Upon receiving a trigger signal, the energy stored in the capacitor is transmitted to a transformer, commonly known as a spark coil, which increases the voltage to cause arcing across the electrodes of a spark plug. Capacitive discharge ignition systems have proven to provide a number of advantages over other types of ignition systems and, thus, are finding their way into even small, inexpensive engines such as lawn mower engines, chain saw engines, and the like.
While capacitive discharge ignition systems store electrical energy in a capacitor, other types of ignition systems, i.e. breaker point or magneto, rely on the inductance of the spark coil to store the energy required for the spark. This significantly increases the size, weight, and cost of the spark coil. In addition, breaker points exhibit a relatively short useful life and traditionally, such systems require periodic maintenance.
A problem common to any gasoline engine operating in an unattended fashion, is the management of the engine in response to widely varying loads. It is a common practice to provide a governor, either to control the speed within a range of speeds or to prevent an over-speed condition. A variety of techniques have been developed for governing the speed of an engine and, for purposes of this application, a governor is any device which automatically regulates the speed of the engine. While some governors adjust the throttle, or fuel injectors, to maintain a fixed engine speed, other governors simply respond to an over-speed condition to prevent damage to the engine or damage to downstream equipment powered by the engine.
Perhaps the most common technique for governing speed is through the control of air or fuel supplied to the engine. This type of governor may be controlled either mechanically or electronically. Typically, an electronic control provides a higher degree of accuracy and reliability. Unfortunately, however, an electronic control also requires some type of electromechanical actuator to adjust the air or fuel. As a result, these governors require a non-trivial amount of electrical power, are relatively expensive, and often exhibit an unacceptable delay in responding to a sudden change in load.
Another known technique for governing the speed of an engine is through manipulation of the timing of, or the presence of, the ignition spark. This type of governor is typically used to prevent an over-speed condition. This may be particularly important where an engine operating under relatively heavy load may suddenly become unloaded. For example, U.S. Pat. No. 4,163,437 issued to Notaras et al, describes a magneto ignition system which uses transistors in lieu of mechanical breaker points. While effective, the governor circuit disclosed by Notaras is imprecise in regard to the governing speed and the device requires the transistors to absorb virtually all of the energy which would otherwise create the ignition spark. This requires the use of transistors which can tolerate significant amounts of energy, even if for relatively short durations.
Thus it is an object of the present invention to provide a capacitive discharge ignition system which includes an electronic governor for a gasoline engine. It is another object of the invention to provide a governor for a gasoline engine which responds rapidly to an over-speed condition and is relatively inexpensive.
SUMMARY OF THE INVENTION
The present invention provides a capacitive discharge ignition system for a gasoline engine which includes an electronic governor. Electrical energy is temporarily stored in a capacitor. At the precise time an ignition spark is needed, a trigger pulse is directed to the gate of a thyristor. The thyristor then becomes conductive to deliver the energy stored in the capacitor to a spark coil, which ultimately results in the generation of a spark across the electrodes of a spark plug. When an over-speed condition is detected, the trigger pulse is inhibited so that the thyristor is not triggered, and thus, energy is never delivered to spark coil to produce the spark, preventing any further increase in the velocity of the engine. Once the speed of the engine is below a threshold speed, the trigger pulse is once again allowed to trigger the thyristor and normal operation resumes.
In a preferred embodiment, a first set of magnets are placed on the flywheel of the engine to interact with a first set of coils placed proximate to the flywheel to generate a voltage for charging the capacitor of the capacitive discharge ignition system. A second set of magnets are attached to the flywheel to interact with a trigger coil to generate the trigger pulse. A speed detector is used to determine the speed of the engine and, upon detection of an over-speed condition, a switch is activated which prevents triggering of the thyristor by the trigger pulse.
In another embodiment, the governor includes an adjustment to allow a user to select the speed at which the trigger pulse will be inhibited. Preferably, the trigger pulse is directed to a frequency-to-voltage (f/v) converter. When the output of the f/v converter exceeds the threshold selected by the user, a transistor is activated to shunt subsequent trigger pulses to prevent triggering of the thyristor. When the output of the f/v converter falls below the user selected threshold, normal operation is resumed.
Further objects, features, and advantages of the present invention will be apparent to those skilled in the art upon examining the accompanying drawings and upon reading the following description of the preferred embodiments.


REFERENCES:
patent: 4170206 (1979-10-01), Katsumata et al.
patent: 4237835 (1980-12-01), Rabus et al.
patent: 4380989 (1983-04-01), Takaki
patent: 4385617 (1983-05-01), Nakata et al.
patent: 4448179 (1984-05-01), Foster
patent: 4503823 (1985-03-01), Shibukawa et al.
patent: 4576138 (1986-03-01), Wolf
patent: 4627398 (1986-12-01), Koike
patent: 4651706 (1987-03-01), Yukawa et al.
patent: 4697560 (1987-10-01), Umehara
patent: 4809661 (1989-03-01), Kinoshita et al.
patent: 5295465 (1994-03-01), Volmary et al.
patent: 5419295 (1995-05-01), Andersson
patent: 5433184 (1995-07-01), Kinoshita et al.
patent: 5806503 (1998-09-01), McLeod
patent: 5816221 (1998-10-01), Krueger
patent: 6388445 (2002-05-01), Andersson
patent: 6408820 (2002-06-01), LaMarr, Jr.
patent: 584618 (1994-03-01), None

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