摘要:
A spark plug having a center electrode (2), a ground electrode (4), and an insulator (3). The ground electrode (4) has a firing surface (4a) formed in a tip end side, and the firing surface (4a) is opposed to a side face of the center electrode (2). The insulator (3) covers the outside of the center electrode (2) and is placed such that a tip end portion (3a) is between the side face of the center electrode (2) and the firing surface (4a) of the ground electrode (4). A discharge high voltage is applied across the center electrode (2) and the ground electrode (4) such that a polarity of the center electrode (2) is positive and that of the ground electrode (4) is negative. The high voltage causes a spark discharge to be generated between the firing surface (4a) of the ground electrode (4) and a tip end portion of the center electrode (2).
摘要:
In a spark plug, a cylindrical metal shell (1) is provided whose inner wall has a rear section and a front section to respectively serve as a diameter-increased section and a diameter-decreased section with a seat portion (11) as a boundary therebetween. An insulator (2) is fixedly placed within the metal shell (1) so that a front end surface (21) of the insulator (2) extends beyond a front end surface (12) of the metal shell (1) with a shoulder portion (231) of an insulator nose (23) engaged against the seat portion (11) of the metal shell (1) by way of a packing (10). A center electrode (3) is fixedly placed within an axial bore (22) of said insulator (2), A ground electrode (4) is connected to the front end surface (12) of the metal shell (1), and bent so that a front end surface (41) of the ground electrode (4) opposes an outer surface (311) of the center electrode (3). The outer surface (311) and a front end surface (31) of the center electrode (3) are provided to respectively serve as a firing portion so as to form a spark discharge gap (Go) with the front end surface (41) of the ground electrode (4), the front end surface (41) of the ground electrode (4) forming an air gap (G) with an outer surface (25) of the insulator (2) so as to release creeping spark discharges along a front end surface (21) of the insulator (2).
摘要:
In a spark plug, a cylindrical metal shell (1) is provided whose inner wall has a rear section and a front section to respectively serve as a diameter-increased section and a diameter-decreased section with a seat portion (11) as a boundary therebetween. An insulator (2) is fixedly placed within the metal shell (1) so that a front end surface (21) of the insulator (2) extends beyond a front end surface (12) of the metal shell (1) with a shoulder portion (231) of an insulator nose (23) engaged against the seat portion (11) of the metal shell (1) by way of a packing (10). A center electrode (3) is fixedly placed within an axial bore (22) of said insulator (2), A ground electrode (4) is connected to the front end surface (12) of the metal shell (1), and bent so that a front end surface (41) of the ground electrode (4) opposes an outer surface (311) of the center electrode (3). The outer surface (311) and a front end surface (31) of the center electrode (3) are provided to respectively serve as a firing portion so as to form a spark discharge gap (Go) with the front end surface (41) of the ground electrode (4), the front end surface (41) of the ground electrode (4) forming an air gap (G) with an outer surface (25) of the insulator (2) so as to release creeping spark discharges along a front end surface (21) of the insulator (2).
摘要:
In a semi-creeping discharge type spark plug, a cylindrical metal shell (1) and an insulator (2) are provided, the latter of which has an axial bore (22) and placed within the metal shell (1) so that a front end of the insulator (2) extends beyond the metal shell (1). A center electrode (3) is placed within the axial bore (22) of the insulator (2) so that a front end surface edge (311) of the center electrode (3) retracts by 0.1~ 0.6 mm behind from a front end surface (23) of the insulator (2) . A ground electrode (4), one end of which is connected to a front end (11) of the metal shell (1), and the other end of which is bent to oppose an outer surface of the insulator (2) so as to form an air-gap (g1) therebetween while permitting creeping spark discharges running along said front end surface (23) of said insulator (2). A foward edge portion (42) of a front end surface (41) of the ground electrode (4) extends by 0.0 ~ 1.0 mm forward from the front end surface (23) of the insulator (2).
摘要:
A spark plug includes an outer electrode including an outer electrode tip of which a distal end surface is spaced from an outer peripheral surface of a leading end portion of a center electrode to define a spark discharge gap. A protruding insulator portion of a cylindrical insulator protrudes at least 1.0 mm from a leading end surface of a cylindrical metal shell. A protruding center electrode portion of the center electrode protrudes at least 3.5 mm from the leading end surface of the cylindrical metal shell. A relationship (θ1+θ2)/2 ≥ 75 degrees is satisfied where the angle θ1 is defined as a central angle (degrees) of a first circular sector having a point B1 as a center thereof, and the angle θ2 is an average value (degrees) of the central angles of two second circular sectors having the point B1 as a center thereof.