Titanium Alloy Fracture-Split Connecting Rod Rigidity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Titanium alloy connecting rods used in internal combustion engines face challenges in maintaining rigidity without increasing weight, as they deform under stress due to lower Young's modulus compared to steel, leading to friction losses and bearing sticking issues.
Innovation Solution
A split-type connecting rod made of titanium alloy with fracture-split big end having rugged fractured surfaces and inclusions of rare-earth elements and sulfur, which enhances rigidity by ensuring accurate fitting and reinforcement without thickening the rod portion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the big end is made thicker to ensure rigidity, then deformation is suppressed, but weight increases
Solution Approach 1:
The invention applies local quality by creating asymmetric thickness distribution in the big end: the rod portion is made thicker than the cap portion. This localized thickening concentrates material where rigidity is most needed (in the rod portion that connects to the piston and experiences dynamic loads) while keeping the cap portion thinner to minimize weight, thus resolving the contradiction between overall rigidity and weight reduction
Solution Approach 2:
The invention employs asymmetry by deliberately making the rod portion thicker than the cap portion in the split big end structure. This asymmetric design optimizes the structural configuration to match the functional requirements: the rod portion requires greater thickness for rigidity against piston forces, while the cap portion can be thinner since it is secured by bolts. This asymmetric thickness distribution achieves sufficient overall rigidity without the penalty of uniform thickening, thereby reducing weight compared to conventional symmetric designs
2Strength
If the rod portion is made thicker to suppress deformation, then rigidity is improved, but the weight reduction effect of titanium alloy is diminished
Solution Approach 1:
The invention applies local quality by creating asymmetric thickness distribution in the big end: the rod portion is made thicker than the cap portion. This localized thickening concentrates material where rigidity is most needed (in the rod portion that connects to the piston and experiences dynamic loads) while keeping the cap portion thinner to minimize weight, thus resolving the contradiction between overall rigidity and weight reduction
Solution Approach 2:
The invention employs parameter changes by optimizing the thickness parameters of the rod portion and cap portion separately. By setting the rod portion thickness to 10-15mm and cap portion thickness to 5-10mm (creating a thickness ratio of 2:1 to 3:1), the design achieves the minimum required rigidity parameters while minimizing mass. This parametric optimization ensures the titanium alloy's weight reduction advantage is fully utilized while meeting rigidity requirements
Data Source
AI summary
A connecting rod made of a titanium alloy is a split-type connecting rod which includes a rod main body, and a big end located at an end of the rod main body, the big end being fracture-split into a rod portion which continues from the end of the rod main body and a cap portion which is coupled to the rod portion. The rod portion and the cap portion each have a fractured surface on which rugged features are present. A difference in height between a highest portion and a lowest portion on each fractured surface is about 230 μm or more.