Spark plug for internal combustion engine

A spark plug for an internal combustion engine, the spark plug comprising:

• a cylindrical ground electrode;
• a cylindrical insulator that is arranged radially inside the ground electrode and includes an insulator protruding portion that protrudes further toward a distal end side in a plug axial direction than a distal end of the ground electrode;
• and
• a center electrode that is held radially inside the insulator and includes an exposed portion that is exposed from a distal end of the insulator protruding portion,
• the spark plug being configured to generate a discharge from the exposed portion of the center electrode to the ground electrode, in a discharge gap that is formed along a surface of the insulator protruding portion, and
• at least one of the exposed portion and the insulator protruding portion comprising
• a flow inlet that penetrates on an outer circumferential surface of the at least one of the exposed portion and the insulator protruding portion,
• a flow outlet that is open toward the discharge gap, and
• a communication passage that communicates between the flow inlet and the flow outlet;
• wherein an area of the flow outlet is smaller than an area of the flow inlet.

A spark plug for an internal combustion engine, the spark plug comprising:

• a cylindrical ground electrode,
• a cylindrical insulator that is arranged radially inside the ground electrode and includes an insulator protruding portion that protrudes further toward a distal end side in a plug axial direction than a distal end of the ground electrode;
• and
• a center electrode that is held radially inside the insulator and includes an exposed portion that is exposed from a distal end of the insulator protruding portion,
• the spark plug being configured to generate a discharge from the exposed portion of the center electrode to the ground electrode, in a discharge gap that is formed along a surface of the insulator protruding portion, and
• at least one of the exposed portion and the insulator protruding portion comprising
• a flow inlet that penetrates on an outer circumferential surface of the at least one of the exposed portion and the insulator protruding portion,
• a flow outlet that is open toward the discharge gap, and
• a communication passage that communicates between the flow inlet and the flow outlet, wherein:
• the flow inlet comprises a plurality of flow inlets that are open in a same side;
• and
• the communication passage communicates with each of the plurality of flow inlets.

A spark plug for an internal combustion engine, the spark plug comprising:

• a cylindrical ground electrode;
• a cylindrical insulator that is arranged radially inside the ground electrode and includes an insulator protruding portion that protrudes further toward a distal end side in a plug axial direction than a distal end of the ground electrode;
• and
• a center electrode that is held radially inside the insulator and includes an exposed portion that is exposed from a distal end of the insulator protruding portion,
• the spark plug being configured to generate a discharge from the exposed portion of the center electrode to the ground electrode, in a discharge gap that is formed along a surface of the insulator protruding portion, and
• at least one of the exposed portion and the insulator protruding portion comprising
• a flow inlet that penetrates on an outer circumferential surface of the at least one of the exposed portion and the insulator protruding portion,
• a flow outlet that is open toward the discharge gap, and
• a communication passage that communicates between the flow inlet and the flow outlet;
• wherein in a state in which the spark plug is attached to the internal combustion engine, the communication passage comprises a portion that is sloped toward a direction, toward a downstream side of a flow direction of a main flow of an air-fuel mixture that passes through a distal end portion of the spark plug, the direction being perpendicular to the flow direction.

A spark plug for an internal combustion engine, the spark plug comprising:

• a cylindrical ground electrode;
• a cylindrical insulator that is arranged radially inside the ground electrode and includes an insulator protruding portion that protrudes further toward a distal end side in a plug axial direction than a distal end of the ground electrode;
• and
• a center electrode that is held radially inside the insulator and includes an exposed portion that is exposed from a distal end of the insulator protruding portion,
• the spark plug being configured to generate a discharge from the exposed portion of the center electrode to the ground electrode, in a discharge gap that is formed along a surface of the insulator protruding portion, and
• at least one of the exposed portion and the insulator protruding portion comprising
• a flow inlet that is open on an outer circumferential surface of the at least one of the exposed portion and the insulator protruding portion,
• a flow outlet that is open toward the discharge gap, and
• a communication passage that communicates between the flow inlet and the flow outlet;
• wherein in a state in which the spark plug is attached to the internal combustion engine, when viewed from the plug axial direction, a virtual straight line that passes through the flow outlet and a plug center shaft is perpendicular to a flow direction of a main flow of an air-fuel mixture that passes through a distal end portion of the spark plug.

A spark plug for an internal combustion engine, the spark plug comprising:

• a cylindrical ground electrode;
• a cylindrical insulator that is arranged radially inside the ground electrode and includes an insulator protruding portion that protrudes further toward a distal end side in a plug axial direction than a distal end of the ground electrode;
• and
• a center electrode that is held radially inside the insulator and includes an exposed portion that is exposed from a distal end of the insulator protruding portion,
• the spark plug being configured to generate a discharge from the exposed portion of the center electrode to the ground electrode, in a discharge gap that is formed along a surface of the insulator protruding portion, and
• at least one of the exposed portion and the insulator protruding portion comprising
• a flow inlet that is open on an outer circumferential surface of the at least one of the exposed portion and the insulator protruding portion,
• a flow outlet that is open toward the discharge gap, and
• a communication passage that communicates between the flow inlet and the flow outlet;
• wherein an area of the flow outlet is smaller than an area of the flow inlet.