Development of telemetry solutions for internal combustion engines

Internal combustion engines (ICEs) will continue to be critical propulsion systems for certain applications in the coming decades. It is therefore extremely important to further develop environmentally friendly and sustainable internal combustion engines. These developments include, but are not limited to, improved tribology and reduced mechanical losses, higher mean effective pressures, compatibility with carbon-free or -neutral fuels, improved exhaust gas aftertreatment systems, and condition-based maintenance. Due to the increased stress on engine components associated with these changes, accurate, online data with high temporal resolution is required from inside the engine. Acquisition of this data can be achieved with a wireless telemetry system in order to minimize the influence of measurement devices on the measurement itself. This paper describes challenges in the development of telemetry systems for internal combustion engines. Systems for measuring the piston temperature, intermediate ring pressures and the axial piston ring movement are briefly presented. A case study is used to illustrate the challenges of developing an inductively powered valve temperature telemetry for large heavy-duty engines. These challenges lie in the processing of the valves and the application of the temperature sensors, the design of the electronics and power supply, as well as the mechanical integration into the engine. Focus is placed on long term stability and preservation of standard valve movement. This article presents two concepts that are designed to meet these requirements in the best possible way. Finally, measurement data will show that the valve temperatures at multiple positions differ from each-other not only in their absolute value, but also in terms of the cycle-to-cycle fluctuations.