Excess demand voltage relief spark plug for vehicle ignition system
A vehicle ignition system is provided that alleviates the problems associated with excessive voltage demand by spark plugs. The ignition system has a spark plug with an electrode and a voltage relief feature operatively connected with the electrode. The voltage relief feature is operable to discharge current from the electrode at a predetermined voltage.
1. A vehicle ignition system comprising:
a spark plug having:
an electrode;
an insulator around the electrode;
a voltage relief feature operatively connected with the electrode and operable to discharge current from the electrode at a predetermined voltage;
wherein the voltage relief feature is positioned within the insulator;
wherein the insulator is located above and beneath the voltage relief feature with respect to a longitudinal direction of the electrode; and
wherein the insulator is characterized by ceramic properties of a first dielectric strength and the voltage relief feature is characterized by ceramic properties of a second dielectric strength lower than the first dielectric strength.
2. The vehicle ignition system of claim 1 , further comprising:
a metal casing surrounding the insulator and the voltage relief feature;
a counter electrode extending from the metal casing to establish a gap between the electrode and the counter electrode; and
wherein the voltage relief feature extends radially through the insulator to the metal casing.
3. A vehicle ignition system comprising:
a spark plug having
an electrode;
a ceramic insulator surrounding the electrode along a length of the electrode;
a voltage relief feature within the ceramic insulator operable to discharge current from the electrode at a predetermined voltage; wherein the ceramic insulator is located above and beneath the voltage relief feature with respect to a longitudinal direction of the electrode;
wherein the insulator is characterized by ceramic properties of a first dielectric strength and the voltage relief feature is characterized by ceramic properties of a second dielectric strength lower than the first dielectric strength;
a metal casing surrounding the ceramic insulator and the voltage relief feature;
a counter electrode extending from the metal casing to establish a gap between the electrode and the counter electrode;
wherein the voltage relief feature extends radially through the ceramic insulator to the metal casing; and
wherein the voltage relief feature only partially radially surrounds the electrode.
4. A spark plug comprising:
a first electrode;
an insulator surrounding the first electrode along a length of the electrode;
a second electrode spaced from the first electrode to define a gap; and
a voltage relief feature within the insulator operable to discharge current from the electrode at a predetermined voltage when an object is in the gap; wherein the insulator is located above and beneath the voltage relief feature with respect to a longitudinal direction of the first electrode;
wherein the insulator is characterized by ceramic properties of a first dielectric strength and the voltage relief feature is characterized by ceramic properties of a second dielectric strength lower than the first dielectric strength;
a metal casing surrounding the insulator and the voltage relief feature and having a threaded portion;
wherein the second electrode extends from the metal casing; and
wherein the voltage relief feature extends radially through the insulator to the metal casing.
5. The spark plug of claim 4 wherein the voltage relief feature only partially radially surrounds the first electrode.