Glow plug quick heating control device

Claim 2

A glow plug heating circuit for use with a glow plug having a heat generating element whose resistance varies with heating temperature comprising; a series connection of said glow plug, a power source, and a current detecting resistor, and switching means for inserting a voltage dropping resistor into said series circuit, so as to vary a current applied to said glow plug in a non-linear manner, wherein said voltage dropping resistor includes a heat generating element the temperature coefficient of which is equal to that of said heat generating element of said glow plug.

Claim 3

A control device with a glow plug heating circuit in which a glow plug having a heat generating element whose resistance varies with heating temperature, a current detecting resistor, and a switching unit are connected in series with a power source, comprising: means for determining the resistance of said heat generating element according to a voltage developed across said current detector resistor; comparator means for providing an output signal when said determined value reaches a set value correspondingly smaller than a predetermined preheating temperature; and switching unit driving means for operating said switching unit in response to an output of said comparator, to open said glow plug heating circuit and to insert a voltage dropping resistor in series in said heating circuit to complete said heating circuit, wherein said voltage dropping resistor includes a heat generating element, the temperature coefficient of which is equal to that of said heat generating element of said glow plug.

Claim 4

A control device with a glow plug heating circuit in which a glow plug having a heat generating element whose resistance varies with heating temperature, a current detecting resistor, and a switching unit are connected in series with a power source, comprising: means for determining the resistance of said heat generating element according to a voltage developed across said current detector resistor; comparator means for providing an output signal when said determined value reaches a set value correspondingly smaller than a predetermined preheating temperature; and switching unit driving means for operating said switching unit in response to an output of said comparator, to open said glow plug heating circuit and to insert a voltage dropping resistor in series in said heating circuit to complete said heating circuit, wherein said voltage dropping resistor includes a heat generating element, the temperature coefficient of which is equal to that of said heat generating element of said glow plug.

Claim 5

A control resistor for use with a glow plug, comprising: a coil including at least two series connected resistance wires having different resistance/temperature characteristics wherein the resistance of said wires substantially equals the resistance of an element of said glow plug; and an insulating material surrounding said coil.

Claim 6

A control resistor for use with a glow plug, comprising: a coil including at least two series connected resistance wires having different resistance/temperature characteristics wherein the resistance of said wires substantially equals the resistance of an element of said glow plug; and an insulating material surrounding said coil.

Claim 7

A control device as claimed in claim 2, said voltage dropping resistor being installed on a cylinder block of said engine so that the temperature of said resistor varies in accordance with the temperature variation of said engine block.

Claim 8

A control device as claimed in claim 2, said switching unit driving means including relay drive circuit means responsive to said comparator output for operating a first relay to open said heating circuit, and timer means for activating a second relay for a predetermined time to connect said voltage dropping resistor in said heating circuit.

Claim 9

A control device as claimed in claim 2, said determining means including a bridge circuit including the resistance of the glow plug and said current detecting resistor.

Claim 10

A control device as claimed in claim 2, said voltage dropping resistor including at least two series connected resistance wires having differing resistance/temperature coefficients.

Claim 11

A device as claimed in claim 2, said resistor having a temperature coefficient substantially equal to that of an element of said glow plug.

Claim 12

A glow plug heating circuit as recited in claim 1, wherein said heat generating element comprises at least two series connected resistance wires having different resistance/temperature coefficients.