Patent ID: 7201043

Claim:
A combustion pressure sensor ( 200 / 400 ) for sensing a combustion pressure of an internal combustion engine, comprising: piezoelectric elements ( 240 , 245 / 440 ) for sensing a change in stress exerted on themselves; a supporting portion ( 250 / 350 / 545 ) for supporting said piezoelectric elements ( 240 , 245 / 440 ); pressure transmitting members ( 210 , 30 / 530 ) having the shape of a bar extending in an axial direction, displaceable relatively in said axial direction with respect to said supporting portion ( 250 / 350 / 545 ) as combustion pressure varies; a pressing portion ( 212 / 412 ) for exerting a pre-load to compress said piezoelectric elements ( 240 , 245 / 440 ) between said pressing portion ( 212 / 412 ) and said supporting portion ( 250 / 350 / 545 ), said pressing portion ( 212 / 412 ) displacing in said axial direction as said pressure transmitting members ( 210 , 30 / 530 ) displace; and electrodes ( 230 , 235 / 430 ) interposed between said supporting member ( 250 / 350 / 545 ) and said pressing portion ( 212 / 412 ), for outputting a change in the stress sensed by said piezoelectric elements ( 240 , 245 / 440 ) as an electric signal, wherein either one of said pressing member ( 212 / 412 ) and said supporting portion ( 250 / 350 / 545 ) is formed with: a first opening ( 255 / 355 / 455 ) for taking out a signal line ( 290 / 490 ) that establishes an electric connection between an external circuit and said electrodes ( 230 , 235 / 430 ); and at least one or more second openings ( 256 / 356 , 357 , 358 / 456 ) that are different from said first opening ( 255 / 355 / 455 ).