Abstract: A glow plug assembly is disclosed having a plug body for mounting the assembly into an engine. A sheath extends from the plug body and has a distal tip portion spaced from the plug body. A first heating element having a fixed resistance is disposed within the sheath and extends from the plug body into the tip portion. A second heating element having a variable resistance is located next adjacent the tip portion separated from the plug body by the first heating element and connected in series with the first heating element. A terminal extends outwardly from the plug body and a power supply is connected to the terminal. A controller between the power supply and the terminal intermittently applies voltage to the terminal for a predetermined time period to maintain an operating temperature. A sensor senses a combined resistance of the first heating element and the second heating element to maintain the combined resistance with the controller by intermittently applying the voltage.

Abstract: A glow plug assembly is disclosed having a plug body for mounting the assembly into an engine. A sheath extends from the plug body and has a distal tip portion spaced from the plug body. A first heating element having a fixed resistance is disposed within the sheath and extends from the plug body into the tip portion. A second heating element having a variable resistance is located next adjacent the tip portion separated from the plug body by the first heating element and connected in series with the first heating element. A terminal extends outwardly from the plug body and a power supply is connected to the terminal. A controller between the power supply and the terminal intermittently applies voltage to the terminal for a predetermined time period to maintain an operating temperature. A sensor senses a combined resistance of the first heating element and the second heating element to maintain the combined resistance with the controller by intermittently applying the voltage.