Обеспечение надежности головных подшипников судовых малооборотных двигателей, работающих на режимах частичных нагрузок

 The paper analyzes the causes of damage to the head bearings of low-speed marine engines of MAN B & W, mainly operating under partial load conditions. It has been established that diesel engines bearings with installed TCCO systems (Turbocharger Cut-Out) are the most damaging. TCCO systems allow gas turbochargers (TC) to be withdrawn from service in order to increase the productivity of the remaining turbochargers and reduce the specific fuel consumption. The results of a dynamic analysis of loading conditions for a bearing assembly are presented using the example of the 12K98MC engine for 100% and 50% Nen modes. It is established that the maximum force acting on the crosshead is 7755 kN and arises at the position of the crankshaft at an angle j = 205 ° and the angle of deflection of the connecting rod β = 8 °. In the operating mode of the engine 12K98MC-C6 100% Nen, no forces occurs in the crank mechanism, which help unload the lower bearing of the head bearing. The authors refute the assumption that there are damages to the antifriction layer of fatigue bearing. It is assumed that the main cause of such damage is the violation of the hydrodynamic lubrication regime with a decrease in the engine speed of the crankshaft. It is indicated the need to change the design of the lower bearing shell of the head bearing in order to increase the bearing capacity. A simplified 3D model of connecting rod and crosshead bearing was developed without a central oil distribution groove. The results of numerical modeling of the contact conditions of the upgraded version of the lower bearing of the head bearing are presented and the character of stress distribution and deformation in the volumes of the AlSn40 antifriction material is studied. It is established that the maximum pres­sure zones are located in the central part of the liner and in its peripheral areas. The obtained results of the investigation of the stressed-deformed state of the lower liner indicate the need to eliminate the axial oil distribution groove and the manufacture of axial oil distribution grooves under a total angle of 68 ... 72 °. The proposed version of the lower liner design at the engine operating mode of 100% Nen senses the maximum stresses and relative deformations in the bearing antifriction material 28 MPa and 22,5 ½ 10-3 respectively.   В работе приведён анализ причин повреждения головных подшипников малооборотных судовых двигателей фирмы MAN B&W, преимущественно работающих на режимах частичных нагрузок. Представлены результаты динамического анализа условий нагружения подшипникового узла на примере двигателя 12K98MC. Авторами опровергается предположение наличия повреждений антифрикционного слоя подшипников усталостного характера. Приведены результаты численного моделирования условий контакта модернизированного варианта нижнего вкладыша головного подшипника. Представлены результаты исследования напряжённо-деформированного состояния нижнего вкладыша и рекомендации по оптимизации его конструкции.