| 摘要 |
<p>An optical pressure sensor for determining the variation of the pressure in an internal combustion engine, comprising a bolt (1) having a through bore (2), a membrane (3) which is mounted in the bore or at one end of said bore and at least one surface of which is reflective, means (5) for causing light to fall on the reflective membrane part and means (7) for measuring the light reflected at the membrane or guiding it to a light-measuring device. In order to achieve the result that the pressure sensor is not sensitive to the intensity of the light source, the distance between the fibre assembly and the membrane, the light loss in the said means, variations in the reflecting power of the membrane surface and the ambient temperature, the means for causing light to fall on the reflective membrane have the form of a ring or sheath (5), means (7 or 6, respectively) being situated both inside said ring or sheath (5) and around said ring or sheath (5) for measuring light reflected at the membrane or guiding it to a light-measuring device. The pressure drop across the membrane is determined from the ratio of the reflected light which is received via the means (6) provided around said ring or sheath (5) and the reflected light which is received via the means (7) provided in the ring or sheath (5). <IMAGE></p> |
