Apparatus for pressure detection in an engine combustion chamber

A device for detecting the pressure in a combustion chamber of an internal combustion engine, comprising:

• a functional member (1, 10, 30) used in the operation of the engine, the functional member passing through the wall of a cylinder head (5) inside an orifice (3) having an axis (11) and formed in this wall, the functional member communicating via this orifice with a combustion chamber (9) of the engine and being intended to be mechanically linked to the cylinder head, with this functional member being able to move axially with respect to the cylinder head under the effect of the pressure in the combustion chamber,
• and a sensor (19, 45, 79) sensing the combustion pressure in this chamber, the sensor being axially pressed against a part (1b, 25, 41) linked to the functional member, via a bearing surface (17, 47, 73) fixed in terms of position with respect to the cylinder head, independently of the pressure in the combustion chamber, so that the sensor detects the displacement of the functional member upon variations in the pressure in the combustion chamber,
• characterized in that:
• a mechanical link between the functional member (1, 10, 30) and the cylinder head (5) is achieved by way of an additional means (15, 17, 43, 47, 73) linked fixedly to this cylinder head,
• and at least part (17, 47, 73) of this additional means exerts pressure on the sensor (19, 45, 79) thereby defining said bearing surface that is fixed in terms of position with respect to the cylinder head when the functional member which is mounted on the cylinder head (5) is in an operational state ready to be subjected to the pressure in the combustion chamber.