Glow plug alternator control
First Claim
1. An apparatus (20) for controlling the resistance of a glow plug (28) over various operating temperature ranges of an internal combustion engine (24), said apparatus comprising:
- means (116) for sensing current through said glow plug (28) and delivering a signal relative to the magnitude of said sensed current;
means (118) for sensing voltage across said glow plug (28) and delivering a signal relative to the magnitude of said sensed voltage;
means (120,122) for modifying said sensed current and voltage signals to include a preselected resistance;
means (124) for comparing said modified current signal to said modified voltage signal to produce a resistance error signal in response to a difference between said compared signals;
means (126) for delivering a voltage signal to said glow plug (28) to control said glow plug'"'"'s resistance relative to said preselected resistance in response to receiving the resistance error signal.
1 Assignment
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Accused Products
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.
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Citations
8 Claims
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1. An apparatus (20) for controlling the resistance of a glow plug (28) over various operating temperature ranges of an internal combustion engine (24), said apparatus comprising:
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means (116) for sensing current through said glow plug (28) and delivering a signal relative to the magnitude of said sensed current; means (118) for sensing voltage across said glow plug (28) and delivering a signal relative to the magnitude of said sensed voltage; means (120,122) for modifying said sensed current and voltage signals to include a preselected resistance; means (124) for comparing said modified current signal to said modified voltage signal to produce a resistance error signal in response to a difference between said compared signals; means (126) for delivering a voltage signal to said glow plug (28) to control said glow plug'"'"'s resistance relative to said preselected resistance in response to receiving the resistance error signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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Specification