Developed Strain Sensors Research Articles

In order to measure the oil-film pressure in engine bearings, the authors developed a new piezo-resistive thin-film pressure sensor. By physical vapor deposition, a sensor film of 3∼6 micrometers thickness was deposited directly on to the engine plain bearing. This kind of sensor has been used to measure high pressure under elastohydrodynamic lubrication on the order of 1 GPa. However, in engine bearings, where relatively low pressure on the order of 10–100 MPa is generated, influences of temperature and strain are not negligible. In the present study, the sensitivity of the sensor could be reduced significantly by optimizing the composition of copper, manganese and nickel contained in the sensor alloy. To reduce the strain sensitivity, the authors developed a twin-arc shape for the sensitive part of the sensor with reduced and uniform strain sensitivity. This allowed a correction of the error in measured pressure due to bearing deformation using a newly developed strain sensor of Ni-Cr-Al alloy. As a result, oil-film pressure could be measured in main bearings and big-end bearings of connecting rods in actual operation. Furthermore, the measurements have revealed that the characteristics of axial distribution of the oil-film pressure change with bearing load. Presented as a Society of Tribologists and Lubrication Engineers Paper at the 2001 Condition Monitoring Conference in San Antonio, TX February 26–28, 2001

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