Measurement of the cylinder pressure in combustion engines with a piezoresistive /spl beta/-SiC-on-SOI pressure sensor

For measuring the cylinder pressure in combustion engines a high temperature pressure sensor has been developed. The sensor is made of a piezoresistive /spl beta/-SiC-on-SOI (SiCOI) sensor chip and a specially designed housing. The SiCOI sensor was characterized under static pressure up to 20 MPa. The sensitivity of the sensor at room temperature is approximately 1.9 mV/MPa and decreases to about 1.2 mV/MPa at 300/spl deg/C. For monitoring the dynamic cylinder pressure in the combustion chamber the SiCOI sensor was placed into the cylinder head of a gasoline engine. The measurements were performed at 1500 rpm under different loads, and for comparison a quartz pressure transducer from Kistier was used as a reference. The maximum pressure at partial load operation amounts to about 2.0 MPa. The difference between the calibrated SiCOI sensor and the reference sensor is significantly less than 0.1 MPa during the whole operation.