Apparatus and method for limiting excessive engine speeds in a light-duty combustion engine

Abstract

A controlled slow down apparatus and method for use in the event that a light-duty combustion engine has entered a state of excessive speeds or auto-ignition. The controlled slow down method is preferably initiated when the engine speed exceeds an activation speed for a predetermined number of engine revolutions. Once initiated, the controlled slow down method uses a combination of ignition timing and spark ratio manipulations in order to disrupt the auto-ignition conditions and slow down the engine in a controlled manner. Preferably, the controlled slow down method is only one part of an overall ignition control method, and can be incorporated within or utilized by one of a number of different ignition timing methods known in the art.

Description

technical field

[0001] The present invention relates generally to ignition systems for light duty internal combustion engines, and more particularly to ignition control circuits and methods for limiting excessive engine speed. Background technique

[0002] As used herein, the term "light duty internal combustion engine" broadly includes all types of non-automotive internal combustion engines including, but not limited to, two-stroke and four-stroke engines used with hand-held power tools, lawn and garden equipment, lawnmowers, Weed trimmers, edge trimmers, chainsaws, snow blowers, personal watercraft, boats, snowmobiles, motorcycles, ATVs and more. Most light duty internal combustion engines have some type of engine speed limiting device which prevents the engine from being subjected to excessively high speeds which could otherwise cause undesired damage or sudden failure.

[0003] For example, it is known to provide a light duty internal combustion engine with means for li...

Images