Glow plug alternator control

Abstract

The present invention pertains to a control system for igniting devices (28,30,32,34,36,38) used in an internal combustion engine (24). In order to ignite alcohol fuel in a diesel engine, the fuel must be heated before or during compression. Glow plugs (28,30,32,34,36,38) conveniently provide heat, but have a short life in such continuous applications. Glow plugs must be accurately controlled to prevent overheating, which leads to open-circuiting. Individual constant voltage controls attempt to provide this function, but are only moderately successful. They are costly and complex, and provide only moderate protection from overheating. Since glow plug resistance correlates to glow plug temperature, resistance control provides better protection against glow plug overheating. Therefore, an apparatus (20) monitors the resistance of a single glow plug (28), and controls the resistance of each glow plug to a preselected resistance value. This preselected resistance value represents a glow plug temperature, that provides satisfactory fuel combustion combined with improved glow plug life. The principal use of the apparatus (20) of the present invention is with internal combustion engines using alternate fuels.

Dependencies are inferred from the claim text.