Patent ID: 7614277

Claim:
A knock sensor comprising: a base made up of: a flange portion; and a tube portion extending axially from said flange portion; a sensor main body including a piezoelectric element that is fitted over an outer peripheral portion of said tube portion; and a stopper ring that is fitted over said outer peripheral portion of said tube portion and cooperates with said flange portion to clamp said sensor main body, a groove extending circumferentially being formed on said outer peripheral surface of said tube portion, and said knock sensor being fixed by driving a pressing jig radially inward toward an outer peripheral surface of said stopper ring to plastically deform said stopper ring and press a protruding portion of said stopper ring into said groove, wherein: an axial length of a recess portion, recessed from said outer peripheral surface of said stopper ring by said pressing jig, is greater than an axial length of said groove, and wherein said recess portion forms a hole within said stopper ring.