Glow plug control circuit

• US 4,375,205 A
• Filed: 07/03/1980
• Issued: 03/01/1983
• Est. Priority Date: 07/03/1980
• Status: Expired due to Term

• Current Assignee: Champion Spark Plug Company
• Original Assignee: Champion Spark Plug Company
• Inventors: Green, Samuel J.
• Primary Examiner(s): Lall, P. S.
• Application Number:
  US06/165,730
• Time in Patent Office: 971 Days
• Field of Search: 123/179 H, 123/179 B, 123/179 BG, 123/145 A, 219/486, 219/492, 219/497, 219/202, 361/264
• US Class Current: 123/179.21
• CPC Class Codes: F02B 3/06 with compression ignition compression ignition engines using air or gas for blowing fuel into compressed air in cylinder F02B13/02
• CPC Class Codes: F02P 19/02 electric, e.g. layout of circuits of apparatus having glowing plugs

Abstract

Apparatus for applying power to at least two heater filaments of two glow plugs in a diesel engine, or to a heater of one glow plug and a ballast load having substantially the same maximum rated voltage as the filament, is disclosed. The power source has a supply voltage greater than the maximum rated voltage of the filament and sufficiently high to cause an overheating temperature capable of burning out the filament under continuous operation. A switch is operable in a first position to prevent the application of the supply voltage to the apparatus, operable in a second position to apply the supply voltage to the apparatus, and operable in a third position to maintain the condition of the second position and to apply the supply voltage to the apparatus and to a starter for the engine. The apparatus comprises means for applying the full supply voltage to each of the filaments by turning the switch from the first to the second position, and means operable, after a preheat time period which varies as an inverse function of available supply voltage and equals the time required to raise a filament from ambient temperature to a higher operating temperature sufficient for diesel engine starting, to reduce the voltage applied to the filaments by the first-named means and to maintain the operating temperature thereof for a prestart time period. The apparatus also includes means operable, after turning the switch from the second to the third position, to continue application of the reduced voltage to the filaments for an afterglow time period predetermined by the amount of time required for smooth engine idling and to minimize engine noise and white smoke emission.

Claims

1. A circuit for use in preheating a diesel engine during starting, said engine having an associated power supply at a predetermined voltage, said circuit comprising first and second glow plugs each having a filament of a predetermined resistance and each having a maximum operating voltage less than such predetermined voltage, said filaments overheating to failure under continuous operation at such predetermined voltage, first switch means having a first position electrically connecting said first and second glow plug filaments in series and a second position electrically connecting said first and second glow plug filaments in parallel, second switch means which, when closed, applies power from the power supply through said first switch means to said filaments, and control means including means for closing said second switch means for a time period from the beginning of a preheat time prior to starting the diesel engine to the end of a predetermined afterglow time period after engine starting required for smooth engine idling and for minimizing engine noise and white smoke emission, means for maintaining said first switch means in said second position during such preheat time for a time period which varies as an inverse function of such predetermined power supply voltage and equals substantially the time required to raise the temperature of said filaments to a temperature sufficient for diesel engine starting and for subsequently changing said first switch means to said first position to reduce the voltage applied to each of said filaments during a prestart time period prior to engine starting and during such afterglow period, and means for opening said second switch means at the end of such afterglow period.

2. Apparatus as claimed in claim 1 and further including signal means for generating an alarm during such prestart period for notifying an engine operator that the diesel engine is ready for starting.

3. Apparatus as claimed in claim 1 or 2 which additionally includes means for preventing the application of the power supply voltage to said filaments and to said signal means for a predetermined period of time after said second switch means is opened.