Investigation of the Piston Pin Movement, Rotation and Oil Filling Ratio of the Piston Boss 2021-01-0646

The general objectives of this research are the identification of relevant factors that influence the movement and rotation behavior of the piston pin and to characterize the oil filling ratio in the piston boss. For this purpose, an experimental measurement campaign with load and speed variation is carried out on an engine test bench. The key challenge is the implementation of the extensive measurement technology on a series V6 engine.

For the detection of the radial piston pin movement in stroke and transversal direction four eddy current sensors are used, two per direction. With a combined measuring principle the oil filling ratio can be determinated. Therefore two additional capacitive sensors are placed between the eddy current sensors. Depending on the hydrodynamic friction conditions in the piston pin bearing as well as the thermal and mechanical boundary conditions, the pivoting movement of the connecting rod initiates the rotation of the piston pin. To record this rotational movement an additional eddy current sensor is applied. Therefore the measuring surface in the inner bore of the piston pin has an electric discharge machined (EDM) spiral contour.

As a result of the large number of measurement wires two linkage systems are applied in one cylinder. The smaller linkage system is connected with the piston, the larger one is applied to the connecting rod. Due to remarkable solutions a successful design and application of the different measuring techniques could be realized. An improved understanding of the piston pin movement behavior can be achieved by evaluating the measurement results and analyzing various influencing factors.