Crankcase Deck Clearances for Large Engine Connecting Rod Assembly
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Solution Overview
Problem
Large internal combustion engines face challenges in assembly due to the increased dimensions and high combustion pressures, which complicate the installation and removal of connecting rods through the cylinder liner, requiring specialized tools and significant effort, especially when the crankshaft must be removed for replacement.
Innovation Solution
The design includes clearances in the upper and lower decks of the crankcase to accommodate the connecting rod's expansion width, allowing for easy installation from above without restricting the large connecting rod eye, eliminating the need to remove the crankshaft for connecting rod replacement and facilitating assembly through aligned cutouts and centering diameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the crankshaft journals are enlarged to accommodate high combustion pressures, then the connecting rod eye must be correspondingly large, but the connecting rod can no longer be easily installed and removed through the cylinder liner's bore
Solution Approach 1:
The crankcase is divided into an upper deck and a lower deck, creating a segmentation that allows the connecting rod to be installed from above through the upper deck opening, separate from the traditional path through the cylinder liner bore. This segmentation resolves the contradiction by providing an alternative installation path that accommodates large connecting rod eyes while maintaining ease of operation.
2Ease of operation
If the receiving bores for the cylinder liner are made larger to allow the connecting rod to pass through, then the connecting rod installation is facilitated, but the position of the cylinder head bolts is negatively affected and their distance from the cylinder is unnecessarily increased
Solution Approach 1:
The invention extracts the connecting rod installation function from the cylinder liner bore path and relocates it to the upper deck opening. This takes out the conflicting requirement of enlarging the receiving bore, allowing the cylinder head bolts to maintain their optimal positioning while the connecting rod is installed through the separate upper deck path.
3Ease of manufacture
If assembly is performed from below as proposed in DE 10 2010 006 958 A1, then the connecting rod can be installed, but specialized tools are required and the crankshaft must be removed for replacement, resulting in considerable additional effort
Solution Approach 1:
Instead of assembling from below as in the prior art, the invention inverts the approach by assembling from above through the upper deck opening. This reversal eliminates the need for specialized tools and complex procedures, allowing the connecting rod to be installed directly from the cylinder head side while the crankshaft remains in place.
Data Source
Figure 1~3
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AI summary
The invention relates to a large internal combustion engine (1) with a crankcase (4), with a crankshaft (11) which is mounted rotatably in said crankcase (4), and with a crankshaft journal (10) on which a connecting rod (9) is pivotably arranged, wherein the crankcase (4) has an upper deck (O) and a lower deck (U) with in each case one opening for the cylinder liner (6), in which opening said cylinder liner (6) is arranged, and wherein the connecting rod (9) has an extent width (A) which is greater than the external diameter (a) of the cylinder liner (6). The problem addressed is that of specifying an improved large internal combustion engine. According to the invention, this is solved by virtue of the fact that the upper deck (O) and/or the lower deck (U) have/has at least one clearance (FO, FU) for the installation of the connecting rod (9), and that the recess which is produced along the external diameter (a) of the cylinder liner (6) opens up at least an extent width (A) of the connecting rod (9) and has a breadth (W) which corresponds at least to a width (b) of the connecting rod (9). Moreover, the invention relates to an associated method for the assembly of the large internal combustion engine (1).