Measurement of Cylinder Bore Deformation by Means of a Turning Piston with a Gap Sensor During Engine Operation

Abstract

Measurements of cylinder bore radial deformation were made along the peripheral direction during actual engine operation. A piston, whose upper part was capable of turning, was installed on the pin boss and was slowly turned from an outside power source by means of a gear train. A heatproof inductance-type gap sensor was embedded on the second land surface. When the engine was under steady-state operation, the piston position at any crank angle was fixed every cycle, not only axially but also inside the corresponding cylinder cross section. As a result, the cylinder bore deformation was continuously measured by one sensor along its entire periphery at one desired axial piston position. One of the important measurement results was that the compound effect of head bolt force and thermal stress had a significant influence on the bore deformation.