| 摘要 |
PURPOSE:To enable the improvement of sensitivity, by a method wherein a pressure gauge, detecting a change in pressure of cooling water, produced in a water jacket due to knocking in a combustion chamber, is connected to the water jacket at a thrust side of a cylinder whereon a piston slaps at a time of an expansion stroke. CONSTITUTION:A detecting hole 9, which is screwed and connected to a water jacket 3, is pierced in a central part of an outer peripheral wall 4 of the water jacket 3 at a thrust side of a cylinder 2 against which a piston 5 is pressed by slapping at a time of an expansion stroke of an engine, and a boltform fitting metal 11 of a pressure gauge 10 is fitted therein. A pressure receiving part 3 protrudes into cooling water in the water jacket 13. A wide change in pressure is created to cooling water in the water jecket 3 due to knocking, it is applied to pressure-receiving films 16, 16, and strain, produced at a strain pipe 17, is detected by a strain gauge 18. A piezo-electric element may be adhered to the same place in the water jacket 3 as described above, or a concave part may be formed in an outer wall at the same place and the pressure-receiving part 13 may be placed in the concavity, and this also permits to perform a high-sensitive measurement. |
