US 4,307,688 AGranted

Diesel engine glow plug energization control system

AssigneeGeneral Motors Corporation

InventorRobert E. Steele

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Abstract

A positive temperature coefficient resistor element of the type that has a substantially constant resistance value when the temperature thereof is less than a selected value and that displays a rapid rise in resistance value when the temperature thereof reaches and increases beyond the selected value is mounted in thermal communication with a Diesel engine and is arranged to be electrically energized and deenergized simultaneously with the engine glow plug energizing circuit. An associated electrical switching arrangement is effective to complete the respective glow plug and resistor element energizing circuits across an operating potential source in response to the application of operating potential and, thereafter, is effective to alternately interrupt and complete the respective glow plug and resistor element energizing circuits in response to the electrical signal developed across the resistor element attaining a predetermined potential level and in response to the electrical signal developed across the resistor element attaining another predetermined potential level, respectively, to cyclically complete and interrupt the glow plug energizing circuit.

Claims5

Dependent claims

A Diesel engine having at least one glow plug;

a source of glow plug energizing potential;
an electrical relay operable between first and second operating conditions to effect, respectively, the connection of said glow plug to and the disconnection of said glow plug from said energizing potential source;
a voltage comparator circuit having first and second input terminals effective to establish said first condition of operation in response to a potential level upon said first input terminal that differs in a selected sense from that upon said second input terminal and to establish said second condition of operation in response to a potential level upon said first input terminal that differs in an opposite sense from that upon said second input terminal;
a positive temperature coefficient resistor element in thermal communication with said engine arranged for energization simultaneously with glow plug energization and effective in response to the self-heating effect thereof while energized and to engine temperature to establish a potential level upon said comparator circuit second input terminal such that the potential level upon said first input terminal differs in said selected sense from that thereby established upon said second input terminal until glow plug temperature reaches at least an ignition temperature at which time the potential level thereby established upon said second input terminal attains a level substantially equal to that of the potential signal upon said first input terminal;
and
circuitry responsive to the operation of said relay from said first to said second operating condition to deenergize said positive temperature coefficient resistor element and said glow plugs for changing the potential level upon said comparator circuit first input terminal to such a value that the potential level thereupon differs in said opposite sense from that upon said second input terminal while said glow plug temperature decreases and responsive to the operation of said relay from said second to said first operating condition for changing the potential level upon said first input terminal to such a value that the potential level thereupon differs in said selected sense from that upon said second input terminal when said glow plug temperature has decreased to a pre-selected lower temperature that is still within the engine ignition range.

3 more elements

A Diesel engine glow plug energization control system for cyclically completing and interrupting a glow plug energizing circuit adapted for connection across an energizing potential source comprising:

an electrical switching arrangement including first and second input terminals that is operable to a first and to a second operating condition to effect, respectively, the completion and interruption to said glow plug energizing circuit in response, respectively, to a potential signal upon said first input terminal that is of a level that differs in a selected sense from that of a potential signal upon said second input terminal and to a potential signal upon said second input terminal that is of a level at least substantially equal to that of a potential signal upon said first input terminal;
a positive temperature coefficient resistor element in thermal communication with an associated engine arranged for energization and deenergization simultaneously with glow plug energization and deenergization and effective in response to the self-heating effect thereof while energized and to engine temperature to establish a potential signal upon said second input terminal of said switching arrangement that attains a level substantially equal to that of the potential signal upon said first input terminal when the temperature of said resistor element has increased to a predetermined value;
and
circuitry adapted for connection across an energizing potential source that, upon initial system energization, is effective to establish a potential signal upon said first input terminal of said electrical switching arrangement that is of a first level that differs in said selected sense from that of the potential signal established upon said second input terminal by said resistor element and thereafter is effective upon the operation of said switching arrangement from said second to said first operating condition in response to these potential signals upon said first and second input terminals to establish a potential signal upon said first input terminal that is of a second level that differs by a greater magnitude of difference in said selected sense from that of said potential signal established by said resistor element upon said second input terminal and is effective upon the operation of said switching arrangement from said first to said second operating condition in response to said potential signal established upon said second input terminal by said resistor element having attained a level substantially equal to that of said potential signal upon said first input terminal when the temperature of said resistor element has increased to said predetermined value to reestablish upon said first input terminal said potential signal of said first potential level.

1 more element

an electrical switching arrangement including first and second input terminals that is operable to a first and to a second operating condition to effect, respectively, the completion and interruption of said glow plug energizing circuit in response, respectively, to a potential signal upon said first input terminal that is of a level that differs in a selected sense from that of a potential signal upon said second input terminal and to a potential signal upon said second input terminal that is of a level at least substantially equal to that of a potential signal upon said first input terminal;
a positive temperature coefficient resistor element in thermal communication with an associated engine arrangement for energization and deenergization simultaneously with glow plug energization and deenergization and effective in response to the self-heating effect thereof while energized and to engine temperature to establish a potential signal upon said second input terminal of said switching arrangement that attains a level substantially equal to that of the potential signal upon said first input terminal when the temperature of said resistor element has increased to a predetermined value;
and
circuit means including first and second resistors connected in series, a third resistor and said switching arrangement adapted for connection across said energizing potential source and interconnected in such a manner that said third resistor is connected in parallel with one of said first and second resistors while said switching arrangement is operated to said first operating condition and is connected in parallel with the other one of said first and second resistors while said switching arrangement is operated to said second operating condition;
and
means for connecting the junction between said first and second resistors to said first input terminal of said electrical switching arrangement.

3 more elements

an electrical switching arrangement including first and second input terminals that is operable to a first and to a second operating condition to effect, respectively, the completion and interruption of said glow plug energizing circuit in response, respectively, to a potential signal upon said first input terminal that is of a level that differs in a selected sense from that of a potential signal upon said second input terminal and to a potential signal upon said second input terminal that is of a level at least substantially equal to that of a potential signal upon said first input terminal;
a positive temperature coefficient resistor element in thermal communication with an associated engine arranged for energization and deenergization simultaneously with glow plug energization and deenergization;
first circuit means including first and second resistors connected in series, a third resistor and said switching arrangement adapted for connection across an energizing potential source and interconnected in such a manner that said third resistor is connected in parallel with one of said first and second resistors while said switching arrangement is operated to said first operating condition and is connected in parallel with the other one of said first and second resistors while said switching arrangement is operated to said second operating condition;
second circuit means including a fourth resistor and said resistor element connected in series, a fifth resistor and said switching arrangement adapted for connection across an energizing potential source and interconnected in such a manner that said fifth resistor is connected in parallel with said fourth resistor while said switching arrangement is operated to said first operating condition and is connected in parallel with said resistor element while said switching arrangement is operated to said second operating condition;
means for connecting the junction between said first and second resistors to a selected one of said input terminals of said electrical switching arrangement;
and
means for connecting the junction between said fourth resistor and said resistor element to the other one of said input terminals of said electrical switching arrangement.

4 more elements

switch means electrically operable to a first and to a second operating condition to effect, respectively, the completion and interruption of said glow plug energizing circuit;
a positive temperature coefficient resistor element in thermal communication with an associated engine arranged for energization and deenergization simultaneously with glow plug energization and deenergization;
first circuit means including first and second resistors connected in series, a third resistor and said switch means adapted for connection across an energizing potential source and interconnected in such a manner that said third resistor is connected in parallel with one of said first and second resistors while said switch means is operated to said first operating condition and is connected in parallel with the other one of said first and second resistors while said switch means is operated to said second operating condition;
second circuit means including a fourth resistor and said resistor element connected in series, a fifth resistor and said switch means adapted for connection across an energizing potential source and interconnected in such a manner that said fifth resistor is connected in parallel with said fourth resistor while said switch means is operated to said first operating condition and is connected in parallel with said resistor element while said switch means is operated to said second operating condition;
control means having first and second input terminals for cyclically operating said switch means to said first and second operating conditions in response, respectively, to a potential signal upon said first input terminal that is of a level that differs in a selected sense from that of a potential signal upon said second input terminal and to a potential signal upon said second input terminal that is of a level at least substantially equal to that of a potential signal upon said first input terminal;
means for connecting the junction between said first and second resistors to said first input terminal of said control means;
and
means for connecting the junction between said fourth resistor and said resistor element to said second input terminal of said control means.

5 more elements

Dependencies are inferred from the claim text.