Hydrolock

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

Abstract: A marine propulsion device includes an internal combustion engine driving a driveshaft into rotation and a starter-generator motor in a torque transmitting relationship with the driveshaft. The starter-generator motor is alternately operable in a positive torque mode where it is powered by a battery to exert a positive torque on the driveshaft, and in a negative torque mode where it exerts a negative torque on the driveshaft and generates a charge to the battery. A control module is configured to receive an engine RPM, determine an engine RPM drop rate, and determine that the engine RPM drop rate exceeds a threshold drop rate. The starter-generator motor is then operated in a positive torque mode based on the engine RPM drop rate when the engine RPM drop rate exceeds the threshold drop rate.

Abstract: Problem. The patterns of a conrod stem deformation during compression of air with a liquid in the internal combustion engine cylinder are considered, and the stem deformation when liquid enters the cylinder (hydrolock) is calculated. It is noted that despite the well-known nature of this damage, no quantitative data are available, which often makes it difficult to determine the damage causes in the practice of ICE operation. Goal of the work is to study the connecting rod deformation mechanism during the loss of stem stability due to hydrolock in the cylinder to obtain quantitative characteristics of this phenomenon, suitable for use in practice to determine the failure causes. Methodology includes simulation of the compression process with a liquid, as well as simulation of the deformation and the buckling of the conrod stem under axial compression. A numerical integration of a system of differential equations describing the change in pressure and air temperature with a liquid in a cylinder by the crankshaft rotation angle is carried out with the initial conditions that were obtained using the standard ICE cycle calculation program. Then the dependence of maximum pressure in the cylinder and the conrod buckling from the combustion chamber filling ratio was determined. Results. For the found strains, the axial deformation of the conrod stem was simulated using the finite element method, the buckling shape of the stem and the stress were determined, and the dependence of the longitudinal bending on the axial deformation of the stem was determined. The simulation results were compared with experimental data on the conrods damages in the ICE operation, as well as with the results of stress calculations using classical methods. Originality. For the first time, a quantitative link was determined between the liquid amount that fell into the internal combustion engine cylinder during hydrolock, the shape of the conrod stem, its axial deformation, and longitudinal bending in case of loss of stability. Practical value. The results can be used in practice when searching for the causes of the internal combustion engines faults, including simulation the ICE damages, in order to clarify the symptoms and causes of the faults associated with hydrolock. Based on the results of the study, the feasibility of the practical application of the damage simulation in studying the fault causes is substantiated. Keywords: internal combustion engine, connecting rod, hydrolock, buckling, simulation.