Assessing the technical possibility of achieving the same piston stroke in a crank mechanism with trailed connecting rods

The article presents the technical capabilities for achieving the specified operating characteristics of engine components and parts taking into account the geometric characteristics of the crank mechanism (crank mechanism). It also presents the assessment and achievements of the required level of strength parameters of some structural elements of the main connecting rod and the entire mechanism as a whole. Making changes to a proven design and established production is a complex and multifactorial task. It is necessary to make changes that would minimize production and technological losses. Besides, they must fit harmoniously into existing technology and production capabilities ensuring the fulfillment of new technical requirements and characteristics. When solving the problem of ensuring the same piston stroke for a V-2 engine, the analysis of the design documentation showed that in addition to making changes to the design of the crank mechanism, it is necessary to make changes to other engine parts. The need for these changes was determined by the method of “scrolling” the assembly of crankshaft parts in the volume of the engine crankcase using 3D modeling programs for parts and checking their performance. The results of assessing the kinematics of the crankshaft engine of V-2 type engines proved that in addition to changing the design of the main connecting rod, it is necessary to perform additional processing of the axial stiffener rib of the upper half of the crankcase, as well as to make changes to the design of the trailing connecting rod in order to eliminate contact with the cylinder liner and, possibly, the liner itself. However, changes in the engine design will entail significant changes in the technological process of its manufacture. Obviously, these changes should be minimal. In order to preserve the engine design, it is necessary to make some significant changes. They can affect significant production and technological changes, which in conditions of mass production require fairly strong theoretical and practical justification. Therefore, when implementing these technical solutions, it was necessary to perform calculation and kinematic analysis based on 3D modeling and logical analysis, excluding disruption of engine operation. In addition, to assess the load on the lower head of the connecting rod, a hydrodynamic calculation was performed. The results also include the hydromechanical characteristics of a complexly loaded bearing and a diagram of the hydrodynamic pressures acting in a thin lubricant layer.