Patent ID: 8198791
Filing Date: 2012-06-12
Classification: H01T

Abstract:
1. A spark plug comprising: a center electrode; a tubular insulator surrounding the circumference of the center electrode and having, on its outer circumferential surface, a rear trunk portion located on a rear end side thereof, and a large diameter portion located frontward of the rear trunk portion and having a diameter greater than that of the rear trunk portion; a tubular metallic shell surrounding the circumference of the insulator and accommodating the large diameter portion of the insulator between a stepped portion formed inside the metallic shell and a crimp portion formed at a rear end portion of the metallic shell, to thereby hold the insulator; a ground electrode provided to form a spark discharge gap in cooperation with the center electrode; and an annular packing interposed between an inner circumferential surface of the crimp portion and an outer circumferential surface of the insulator, the spark plug being characterized in that a cushioning member is interposed between the insulator and at least the crimp portion or the packing, whichever is closer to the insulator.