Abstract: A spark plug 1 includes a housing 2, an insulator 3, a center electrode 4 held inside the insulator 3 such that a distal end portion 41 protrudes, a ground electrode 5 including a standing portion 51 and an opposing portion 52, and a guide member 22 that has a guide surface 221 facing the standing portion 51 of the ground electrode 5 and functions to guide a flow of an air-fuel mixture in a combustion chamber of an internal combustion engine to a spark discharge gap G formed between the center electrode 4 and the opposing portion 52 of the ground electrode 5. The opposing portion 52 of the ground electrode 5 has an opposing surface 521 that opposes the center electrode 4, a back surface 522 on the opposite axial side to the opposing surface 521, and a pair of side surfaces 523 and 524 that connect the opposing surface 521 and the back surface 522.

Abstract: A spark plug for an internal combustion engine has a housing, an insulator, a center electrode, a ground electrode, and a tip projecting portion. The tip projecting portion has an air guiding surface. In the spark plug, when viewed from a plug axial direction, a straight line that connects the center, in the plug circumferential direction, of the erect portion of the ground electrode and a center point of the center electrode is a straight line. An extension line of the air guiding surface is a straight line. A distance between an intersection, between the straight line and the straight line, and the center point of the center electrode is a (positive towards the side moving away from the erect portion. An angle formed by the straight line and the straight line is b. A diameter of the housing is D. At this time, all of b??67.8×(a/D)+27.4, b??123.7×(a/D)+64.5, ?0.4?(a/D)?0.4, and 0°<b?90° are satisfied.

Abstract: A spark plug 1 includes a housing 2, an insulator 3, a center electrode 4 held inside the insulator 3 such that a distal end portion 41 protrudes, a ground electrode 5 including a standing portion 51 and an opposing portion 52, and a guide member 22 that has a guide surface 221 facing the standing portion 51 of the ground electrode 5 and functions to guide a flow of an air-fuel mixture in a combustion chamber of an internal combustion engine to a spark discharge gap G formed between the center electrode 4 and the opposing portion 52 of the ground electrode 5. The opposing portion 52 of the ground electrode 5 has an opposing surface 521 that opposes the center electrode 4, a back surface 522 on the opposite axial side to the opposing surface 521, and a pair of side surfaces 523 and 524 that connect the opposing surface 521 and the back surface 522.

Abstract: A spark plug for an internal combustion engine has a housing, an insulator, a center electrode, a ground electrode, and a tip projecting portion. The tip projecting portion has an air guiding surface. In the spark plug, when viewed from a plug axial direction, a straight line that connects the center, in the plug circumferential direction, of the erect portion of the ground electrode and a center point of the center electrode is a straight line. An extension line of the air guiding surface is a straight line. A distance between an intersection, between the straight line and the straight line, and the center point of the center electrode is a (positive towards the side moving away from the erect portion. An angle formed by the straight line and the straight line is b. A diameter of the housing is D. At this time, all of b??67.8×(a/D)+27.4, b?123.7×(a/D)+64.5, ?0.4?(a/D)?0.4, and 0°<b?90° are satisfied.

Abstract: A spark plug for internal combustion engines is provided, where the spark plug includes a cylindrical housing, a cylindrical insulation porcelain part, a center electrode, and a ground electrode. The insulation porcelain is housed in the housing and the center electrode is held inside the insulation porcelain. The ground electrode protrudes from a top end portion of the housing. A spark discharge gap is left between the ground and center electrodes. Further, first to third projections are formed on the top end portion. The first projection is opposed to the ground electrode with the center electrode therebetween. The second projection is closer to the ground electrode than to the first projection. The third projection is closer to the first projection than to the ground electrode.

Abstract: A spark plug for internal combustion engines is provided, where the spark plug includes a cylindrical housing, a cylindrical insulation porcelain part, a center electrode, and a ground electrode. The insulation porcelain is housed in the housing and the center electrode is held inside the insulation porcelain. The ground electrode protrudes from a top end portion of the housing. A spark discharge gap is left between the ground and center electrodes. Further, first to third projections are formed on the top end portion. The first projection is opposed to the ground electrode with the center electrode therebetween. The second projection is closer to the ground electrode than to the first projection. The third projection is closer to the first projection than to the ground electrode.

Abstract: A spark plug for an internal combustion engine is provided which is equipped with a tip protrusion disposed on a top of a hollow cylindrical housing of the spark plug. The spark plug also includes a center electrode retained in a porcelain insulator disposed inside the housing and a ground electrode is joined to the housing so as to form a spark gap. The tip protrusion serves to direct a flow of gas to be ignited by a spark produced in the spark gap and is shaped to have a radial width extending in a radial direction of the housing and a circumferential width extending in a circumferential direction of the cylindrical housing. The radial width is greater than the circumferential width. This enhances the efficiency in guiding the flow of gas toward the spark gap.

Abstract: A spark plug for internal-combustion engines includes a housing, an insulator, a center electrode, and an earth electrode. A gas guiding sections equipped with slopes that slope inwardly as they approach toward a tip side from a circumference surface of the housing and guide surfaces that are disposed on both sides in a circumferential direction of the slopes are formed in a tip part of the housing. The gas guiding sections are formed in the circumferential direction within a 90-degree range measured relative to the center of the earth joint section, which is a junction of the housing and the earth electrode, in the circumferential direction. When the spark plug is mounted to the engine, it is constituted so that the gas guiding sections are projected into a combustion chamber.

Abstract: A spark plug for an internal combustion engine is provided which is equipped with a tip protrusion disposed on a top of a hollow cylindrical housing of the spark plug. The spark plug also includes a center electrode retained in a porcelain insulator disposed inside the housing and a ground electrode is joined to the housing so as to form a spark gap. The tip protrusion serves to direct a flow of gas to be ignited by a spark produced in the spark gap and is shaped to have a radial width extending in a radial direction of the housing and a circumferential width extending in a circumferential direction of the cylindrical housing. The radial width is greater than the circumferential width. This enhances the efficiency in guiding the flow of gas toward the spark gap.

Abstract: A spark plug for internal-combustion engines includes a housing, an insulator, a center electrode, and an earth electrode. A gas guiding sections equipped with slopes that slope inwardly as they approach toward a tip side from a circumference surface of the housing and guide surfaces that are disposed on both sides in a circumferential direction of the slopes are formed in a tip part of the housing. The gas guiding sections are formed in the circumferential direction within a 90-degree range measured relative to the center of the earth joint section, which is a junction of the housing and the earth electrode, in the circumferential direction. When the spark plug is mounted to the engine, it is constituted so that the gas guiding sections are projected into a combustion chamber.

Abstract: A laser ignition system includes a laser oscillator and an oscillation controller. The laser oscillator is configured to generate laser light into a combustion chamber of an engine. The oscillation controller is configured to cause the laser oscillator to generate a plurality of laser pulses into the combustion chamber in order to ignite the engine. The oscillation controller causes the laser oscillator to generate each of the plurality of laser pulses at a laser oscillation period that is longer than 10 ?s and shorter than 300 ?s.

Abstract: In a guide groove of a guide rotator of a valve timing control apparatus, a stopper surface is planar and is positioned in an end of the guide groove. The stopper surface is engageable with a cylindrical outer peripheral surface of a movable body, which is received in the guide groove, to stop the movable body. An arcuate outer connection surface connects between the stopper surface and an outer guide surface and has a radius of curvature, which is smaller than that of the cylindrical outer peripheral surface of the movable body. An arcuate inner connection surface connects between the stopper surface and an inner guide surface and has a radius of curvature, which is smaller than that of the cylindrical outer peripheral surface of the movable body.

Abstract: In a valve timing controller, the guide-groove biases the moving element in a direction in which the moving element slides with respect to a radial line connecting a center of the guide-rotational element and the moving element, when the guide-rotational element relatively rotates with respect to the first rotational element. The direction in which the moving elements are pushed and the direction in which the moving elements moves are substantially identical to each other.

Abstract: A valve timing controller includes a guide rotation member provided with a guide groove, a bearing rotation member radially supporting the guide rotation member, and a plurality of movable bodies sliding in the guide groove in accordance with a rotation of the guide rotation member. A plurality of link mechanisms connects the bearing rotation member with each one of movable bodies respectively, and rotates the bearing rotation member in accordance with a movement of the movable bodies. The valve timing of at least one of the intake valve and the exhaust valve is adjusted in accordance with a rotation of the bearing rotation body. A clearance gap is provided between the guide rotation member and the bearing rotation member in order to permit a relative radial movement of the guide rotation member with respect to the bearing rotation member.

Abstract: In the case where an intake valve has its phase in a first region between a most retarded angle and CA(1), the rotational speed of relative rotation between an output shaft of an electric motor and a sprocket is reduced at a reduction gear ratio R(1) to change the phase of the intake valve. In the case where the intake valve has its phase in a second region between CA(2) and a most advanced angle, the rotational speed of relative rotation is reduced at a reduction gear ratio R(2) to change the phase of the intake valve. As long as the rotational direction of relative rotation is the same, the phase of the intake valve is changed in the same direction for both of the first region between the most retarded angle and CA(1) and the second region between CA(2) and the most advanced angle.

Abstract: A valve timing controller includes a guide rotation member provided with a guide groove, a bearing rotation member radially supporting the guide rotation member, and a plurality of movable bodies sliding in the guide groove in accordance with a rotation of the guide rotation member. A plurality of link mechanisms connects the bearing rotation member with each one of movable bodies respectively, and rotates the bearing rotation member in accordance with a movement of the movable bodies. The valve timing of at least one of the intake valve and the exhaust valve is adjusted in accordance with a rotation of the bearing rotation body. A clearance gap is provided between the guide rotation member and the bearing rotation member in order to permit a relative radial movement of the guide rotation member with respect to the bearing rotation member.

Abstract: In a guide groove of a guide rotator of a valve timing control apparatus, a stopper surface is planar and is positioned in an end of the guide groove. The stopper surface is engageable with a cylindrical outer peripheral surface of a movable body, which is received in the guide groove, to stop the movable body. An arcuate outer connection surface connects between the stopper surface and an outer guide surface and has a radius of curvature, which is smaller than that of the cylindrical outer peripheral surface of the movable body. An arcuate inner connection surface connects between the stopper surface and an inner guide surface and has a radius of curvature, which is smaller than that of the cylindrical outer peripheral surface of the movable body.

Abstract: In a valve timing controller, the guide-groove biases the moving element in a direction in which the moving element slides with respect to a radial line connecting a center of the guide-rotational element and the moving element, when the guide-rotational element relatively rotates with respect to the first rotational element. The direction in which the moving elements are pushed and the direction in which the moving elements moves are substantially identical to each other.

Abstract: In the case where an intake valve has its phase in a first region between a most retarded angle and CA(1), the rotational speed of relative rotation between an output shaft of an electric motor and a sprocket is reduced at a reduction gear ratio R(1) to change the phase of the intake valve. In the case where the intake valve has its phase in a second region between CA(2) and a most advanced angle, the rotational speed of relative rotation is reduced at a reduction gear ratio R(2) to change the phase of the intake valve. As long as the rotational direction of relative rotation is the same, the phase of the intake valve is changed in the same direction for both of the first region between the most retarded angle and CA(1) and the second region between CA(2) and the most advanced angle.

Abstract: A valve timing adjustment device for promptly switching a rotational phase includes a guide rotary body having a guide passage containing a movable body. The guide passage includes a variable radial dimension relative to a rotational centerline. The guide rotary body rotates relative to a driving rotary body and guides the movable body in the guide passage. A phase change mechanism changes the rotational phase of a driven shaft relative to a drive shaft according to the position of the movable body in the guide passage. The guide passage has a gradually decreasing region and a gradually increasing region. The gradually decreasing region slants toward an axis of the guide rotary body. The gradually increasing region slants relative toward the axis of the guide rotary body. The gradually decreasing region and the gradually increasing region are connected.