Politecnico di Torino - Corso Duca degli Abruzzi, 24 - 10129 Torino, ITALY

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System for evaluating the pressure in the cylinder

connecting rodcylinderfluid machinesPressurestrain gauges


The proposed invention concerns a low-cost non-intrusive system for evaluating the pressure in the cylinder by monitoring the mechanical stresses which are determined on the connecting rod of reciprocating fluid machines with push crank mechanism.

Technical features

The invention discussed here presents a cost-effective and non-intrusive system for determining the in-cylinder pressure in alternative fluid machinery, such as internal combustion engines and reciprocating compressors. It employes strain gauge measurements to monitor stress and deformation of the connecting rod, from which it is possible to provide a reliable, high-fidelity reconstruction of the in-cylinder pressure signal in real-time. The optimal set-up and calibration procedure useful at obtaining the best measurement accuracy were determined by means of extensive numerical and experimental campaigns. The system also exploits a wireless (or wired) transmission device to capture and digitize the voltage signal from the strain gauge measurements, along with an acquisition and processing system that correlates the signal to the in-cylinder pressure. The processed data can be used for closed-loop control systems in engine control units, allowing for real-time adjustments in operational parameters.
TRL: 2

Possible Applications

  • Automotive;
  • Aerospace and Marine;
  • Energy production;
  • Industrial machines;
  • R&D of engine manufacturers and aftermarket solutions.


  • Accurate and reliable measurement;
  • Does not require any structural modification of the engine;
  • Does not require resistance to high pressures and temperatures;
  • Low cost.