Combustion pressure sensor and glow plug including the same

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).