Study of the conrod deformation during piston interaction with liquid in the internal combustion engine cylinder

Abstract

The paper analyzes the deformation of the connecting rod stem with buckling due to water ingress into the internal combustion engine cylinder (the so-called hydrolock). A method is presented that has been developed to perform calculations of stem deformation in the process of compressing air with liquid in an internal combustion engine cylinder. The method is based on solving a system of differential equations for pressure and temperature in the cylinder, followed by calculating the compression force acting on the connecting rod. A carried-out simulation of the compression process demonstrates the dependence of the air pressure in the cylinder, the stress and the strain of the connecting rod on the fill ratio of the combustion chamber with liquid. The calculations performed according to the classical theory of resistance of materials have shown that the connecting rod with the buckling of the stem begins to deform when the liquid fills the combustion chamber to a minimum of 80%. With the increase in the amount of liquid, the deformation of the conrod increases, and when the level of liquid filling is so significant that it exceeds the volume of the combustion chamber, the conrod stem deformation reaches extreme values. It is shown that under these conditions after the hydrolock occurs the engine may fail due to the piston wedging the crankshaft in the bottom dead center position.

Building a mathematical model of the destruction of a connecting rod-piston group in the car engine at hydraulic lock

“…The initial data adopted for the simulation included the geometric dimensions and material characteristics of the main parts of the connecting rod-piston group. A steel connecting rod with a traditional I-beam rod profile of 20 ×12 mm with a base of 4 mm and shelves 3 mm thick was chosen [12]. In addition, a typical piston made of piston aluminum alloy of a car engine for a cylinder with a diameter of 83 mm and a steel piston pin with a diameter of 22 mm were taken for modeling [16].…”

“…Based on the known data acquired during the simulation of the loss of stability of the connecting rod [3,12], a connection was established between the deformation of the connecting rod and the pressure force acting on the piston. After that, the deformation (ovalization) of the piston pin was determined by calculation.…”

“…However, for some cases and types of damage where parts experience significant overloads, missing data and a solution can be found. Such damage includes the deformation of parts during hydrolock from liquid ingress in the cylinder [12]. However, these data do not have a quantitative characteristic.…”

“…This directly follows from the results of the loop calculation performed using the Lotus Engine Simulation program [15]. When compressing with a liquid in a cylinder, the pressure in the cylinder is not just significant but many times higher than the usual level due to the replacement of part of the volume with an incompressible liquid [12]. In this case, the influence of inertial forces on the process will be even less, and they can be generally neglected.…”

Investigation and failure analysis of a diesel generator connecting rod

“…Several inspection reports on connecting rods were found to determine and make appropriate maintenance recommendations [9], [10]. In other cases, follow-up inspection of connecting rod failure was reported by hardness test, surface crack analysis, and microstructure analysis due to overheating [4], [11], [12].…”