Abstract
In addition to a further reduction in fuel consumption and emissions, the current focus of internal combustion engine development is on system integration of the engine and its components to ensure perfect engine operation and high engine performance over the entire service life of the engine. Extensive sensor application allows acquisition, storage and intelligent processing of numerous engine parameters in digital engine control systems. Intelligent software platforms are increasingly being used to fully exploit the data generated by sensor systems and ensure optimal engine operation. This paper deals with new concepts for measuring physical quantities that are characteristic of sliding bearings. It describes the development of a flexible and multifunctional sensor technology for real-time measuring of temperature and pressure as well as the signal transfer and data acquisition from moving parts to outside the engine.
The sensor technology required for such a system must meet the challenges of defining a quickly responding method that captures the measured variable as close to the bearing surface as possible in order to detect bearing failures in advance. The system must be able to withstand the high temperatures and mechanical loads inside the engine. In addition, fast wireless data transfer of signals acquired from moving components such as conrod bearings is necessary. A highly flexible sensor package based on thin-film technology was developed to meet these requirements. The sensor is integrated into the bearing shell and has the potential to be employed in series application. A robust telemetry unit able to withstand harsh environmental conditions such as high temperature and extremely high centrifugal forces was developed that transfers the measured data to engine ECU or other external devices. At the same time, transmission rate, distances and power demand are subject to stringent requirements.
To create a comparative basis for further verification of bearings with thin film sensor technology and to gain insight into the temperature distribution in the bearing gap, measurements with conventional sensor technology that assesses temperatures directly inside the lubrication gap were undertaken on a bearing test rig as well as on a multicylinder heavy duty diesel truck engine. The results of these investigations also provide a fundamental understanding of the temperature distribution in the bearing gap for crankshaft as well as for conrod bearings. The results of ongoing investigations will include a validation of the new temperature measurement method based on thin film technology under real engine conditions.
