Abstract: An exhaust purification device has a catalytic converter provided with: an outer cylinder welded at the upstream end portion to an exhaust gas inlet of an inlet-side flange and welded at the downstream end portion to an exhaust gas outlet of the outlet-side flange. An inner cylinder has an upstream end portion held by the upstream side portion of the outer cylinder with no gap and has a downstream end portion disposed at the downstream side of the outer cylinder with a gap, the inner cylinder housing a catalyst support. An opening end is formed at the downstream end portion of the inner cylinder with a gap with respect to the outer cylinder, and a gas layer is formed by the exhaust gas having entered from the exhaust gas inlet and convected to an upstream side between the outer cylinder and the inner cylinder.

Abstract: An exhaust purification device has a catalytic converter provided with: an outer cylinder welded at the upstream end portion to an exhaust gas inlet of an inlet-side flange and welded at the downstream end portion to an exhaust gas outlet of the outlet-side flange. An inner cylinder has an upstream end portion held by the upstream side portion of the outer cylinder with no gap and has a downstream end portion disposed at the downstream side of the outer cylinder with a gap, the inner cylinder housing a catalyst support. An opening end is formed at the downstream end portion of the inner cylinder with a gap with respect to the outer cylinder, and a gas layer is formed by the exhaust gas having entered from the exhaust gas inlet and convected to an upstream side between the outer cylinder and the inner cylinder.

Abstract: A spark plug having a noble metal tip that is joined to a tip-joining surface of a ground electrode so as to face an end face of a center electrode. When the noble metal tip is projected onto a projection plane parallel to the tip-joining surface, the noble metal tip has an elliptical shape in the projection plane. When the ground electrode is also projected onto the projection plane, an angle of 45° or less is formed between the major axis of the elliptical shape in the projection plane and a straight line extending in the lengthwise direction of the ground electrode and passing through the center of the noble metal tip in the projection plane.

Abstract: An electrode of the spark plug includes a first melt portion formed between a body portion of an intermediate member and a noble metal tip; and a second melt portion that is formed, between a flange portion of the intermediate member and an electrode base material, at least at a position of intersection with an axial line of the noble metal tip. In a cross section including the axial line of the noble metal tip, when: a diameter of the noble metal tip is denoted by Tw; the shortest distance between the second melt portion and a boundary between the first melt portion and the intermediate member is denoted by S1; and the longest distance between the second melt portion and the boundary between the first melt portion and the intermediate member is denoted by S2, 1.0 mm?Tw?1.2 mm and (S2?S1)?0.3 mm are met.

Abstract: A spark plug that satisfies the relation 2.8?(A+B)/M, where A is the sum of a length A1 of contact between a sheet packing and a metallic shell of a spark plug in one half section and a length A2 of contact between the sheet packing and the insulator in the one half section, and B is the sum of a length B1 of contact between the sheet packing and the metallic shell in the other half section and a length B2 of contact between the sheet packing and the insulator in the other half section. M is the difference obtained by subtracting the inner diameter D of a ledge from the inner diameter C of a middle hole portion.

Abstract: An electrode of the spark plug includes a first melt portion formed between a body portion of an intermediate member and a noble metal tip; and a second melt portion that is formed, between a flange portion of the intermediate member and an electrode base material, at least at a position of intersection with an axial line of the noble metal tip. In a cross section including the axial line of the noble metal tip, when: a diameter of the noble metal tip is denoted by Tw; the shortest distance between the second melt portion and a boundary between the first melt portion and the intermediate member is denoted by S1; and the longest distance between the second melt portion and the boundary between the first melt portion and the intermediate member is denoted by S2, 1.0 mm?Tw?1.2 mm and (S2?S1)?0.3 mm are met.

Abstract: A spark plug having a noble metal tip that is joined to a tip-joining surface of a ground electrode so as to face an end face of a center electrode. When the noble metal tip is projected onto a projection plane parallel to the tip-joining surface, the noble metal tip has an elliptical shape in the projection plane. When the ground electrode is also projected onto the projection plane, an angle of 45° or less is formed between the major axis of the elliptical shape in the projection plane and a straight line extending in the lengthwise direction of the ground electrode and passing through the center of the noble metal tip in the projection plane.

Abstract: A spark plug includes: an insulator having an axial hole; a conductive member disposed around the insulator; a center electrode disposed inside the axial hole, having a bar shape extending in the axial direction, and located on a rear end side with respect to a front end of the conductive member; a ground electrode forming a spark gap between the ground electrode and the center electrode; and a connection part including a plurality of spokes extending in a radial direction whose inner ends are connected to the ground electrode, and connecting the conductive member to the ground electrode. The connection part includes a joint part that is jointed to an inner surface of the conductive member, and the ground electrode has at least one of a notch and a groove at a position that is different from a position connected to the spokes in a circumferential direction.

Abstract: A spark plug that satisfies the relation 2.8?(A+B)/M, where A is the sum of a length A1 of contact between a sheet packing and a metallic shell of a spark plug in one half section and a length A2 of contact between the sheet packing and the insulator in the one half section, and B is the sum of a length B1 of contact between the sheet packing and the metallic shell in the other half section and a length B2 of contact between the sheet packing and the insulator in the other half section. M is the difference obtained by subtracting the inner diameter D of a ledge from the inner diameter C of a middle hole portion.

Abstract: A spark plug where a predetermined cross section of a noble metal tip is divided by a vertical line into two half cross sections having a first half cross section and a second half cross section. The first half cross section satisfies h1/t?0.2 and Rw1/Rt1?1.03, and the second half cross section satisfies h2/t?0.2 and Rw2/Rt2?1.03. At a welding interface, an oxidation scale progresses in a direction away from an axis along side surfaces and changes the progressing direction at the end points so as to progress in a direction toward the axis along bottom surfaces. The progress of the oxidation scale is restrained. Since the noble metal tip is held by an engagement portion of a ground electrode, separation of the noble metal tip from the ground electrode 40 can be restrained.

Abstract: A spark plug includes: an insulator having an axial hole; a conductive member disposed around the insulator; a center electrode disposed inside the axial hole, having a bar shape extending in the axial direction, and located on a rear end side with respect to a front end of the conductive member; a ground electrode forming a spark gap between the ground electrode and the center electrode; and a connection part including a plurality of spokes extending in a radial direction whose inner ends are connected to the ground electrode, and connecting the conductive member to the ground electrode. The connection part includes a joint part that is jointed to an inner surface of the conductive member, and the ground electrode has at least one of a notch and a groove at a position that is different from a position connected to the spokes in a circumferential direction.

Abstract: A spark plug has a center electrode having an electrode base member and a core material which is disposed in the electrode base member and which predominantly contains copper, and a noble metal tip disposed at a forward end of the center electrode, and a fusion portion formed between the noble metal tip, and the electrode base member and the core material. The fusion portion is in contact with the core material in a cross section which is parallel to the center axis of the center electrode and which passes through the center axis and the fusion portion. The fusion portion contains a component of the noble metal tip, a component of the electrode base member, and a copper component forming the core material.

Abstract: A spark plug has a center electrode having an electrode base member and a core material which is disposed in the electrode base member and which predominantly contains copper, and a noble metal tip disposed at a forward end of the center electrode, and a fusion portion formed between the noble metal tip, and the electrode base member and the core material. The fusion portion is in contact with the core material in a cross section which is parallel to the center axis of the center electrode and which passes through the center axis and the fusion portion. The fusion portion contains a component of the noble metal tip, a component of the electrode base member, and a copper component forming the core material.

Abstract: A spark plug where a predetermined cross section of a noble metal tip is divided by a vertical line into two half cross sections having a first half cross section and a second half cross section. The first half cross section satisfies h1/t?0.2 and Rw1/Rt1?1.03, and the second half cross section satisfies h2/t?0.2 and Rw2/Rt2?1.03. At a welding interface, an oxidation scale progresses in a direction away from an axis along side surfaces and changes the progressing direction at the end points so as to progress in a direction toward the axis along bottom surfaces. The progress of the oxidation scale is restrained. Since the noble metal tip is held by an engagement portion of a ground electrode, separation of the noble metal tip from the ground electrode 40 can be restrained.