Spark plug with ground electrode in a recess on housing end side
A spark plug with a longitudinal axis. The spark plug includes a housing with a hole along the spark plug longitudinal axis and a combustion-chamber-side end side, wherein the housing has a recess on the end side thereof; an insulator arranged inside the housing; a central electrode arranged inside the insulator; and a ground electrode arranged in one of the recesses on the housing end side; wherein the ground electrode and the central electrode are arranged such that an ignition gap is formed within the housing.
1 . A spark plug with a longitudinal axis, comprising:
a housing with a hole along the spark plug longitudinal axis and a combustion-chamber-side end side, wherein the housing has a recess on the combustion-chamber-side end side of the housing;
an insulator arranged inside the housing;
a central electrode arranged inside the insulator; and
a ground electrode arranged in the recess on the combustion-chamber-side end side of the housing;
wherein the ground electrode and the central electrode are arranged such that an ignition gap is formed within the housing,
wherein the recess extends from the combustion-chamber-side end side of the housing towards the housing end facing away from the combustion chamber,
wherein the ground electrode is located at the lowest point of the recess,
wherein the recess has a depth such that the ignition gap is arranged entirely within the housing, and wherein neither the central electrode nor the ground electrode protrudes into the combustion chamber.
2 . The spark plug according to claim 1 , wherein the recess is a rectangular notch.
3 . The spark plug according to claim 2 , wherein the combustion-chamber-side end side of the housing has a wave contour, a wave trough being the recess in which the ground electrode is arranged.
4 . The spark plug according to claim 2 , wherein the recess has a depth T, wherein Tis 0.1 mm≤T≤15 mm.
5 . The spark plug according to claim 1 , wherein the combustion-chamber-side end side of the housing includes two or more recesses, the ground electrode being arranged in one on the recesses.
6 . The spark plug according to claim 5 , wherein two of the recesses are arranged opposite one another or at an angle of 100°-80° relative to one another.
7 . The spark plug according to claim 1 , wherein: (i) the ground electrode is formed as a roof electrode and forms an axial ignition gap with the central electrode, or (ii) the ground electrode is formed as a side electrode and forms a radial ignition gap with the central electrode.
8 . The spark plug according to claim 1 , wherein the ignition gap is not greater than 0.5 mm.
9 . The spark plug according to claim 1 , wherein the spark plug is a hydrogen spark plug which is configured to be used in an engine operated with hydrogen and to ignite an ignitable hydrogen-containing fuel-air mixture.