Engine Connecting Rod Lattice Structure for Rigidity
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Solution Overview
Problem
Conventional connecting rods in engines face challenges in maintaining rigidity while minimizing weight, leading to increased inertia, reduced output power, worsened fuel efficiency, and increased vibration due to the addition of reinforcing ribs for twisting vibration suppression.
Innovation Solution
A connecting rod design featuring a plate-shaped connecting portion with four vertical reinforcing portions and oblique reinforcing portions that extend in a longitudinal direction, forming a lattice structure, which enhances bending and twisting rigidity while maintaining a lightweight structure through recessed portions, allowing for improved moldability and reduced weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If reinforcing ribs are added to suppress twisting vibration, then rigidity in twisting direction is improved, but weight of connecting rod increases
Solution Approach 1:
The connecting rod is divided into multiple functional zones: the connecting portion with lattice structure for twisting rigidity, the longitudinal portion for bending rigidity, and strategic placement of reinforcing ribs only where needed. This segmentation allows each portion to be optimized independently, achieving high rigidity without unnecessary weight addition.
Solution Approach 2:
Reinforcing ribs are placed locally at specific positions (connecting portion and longitudinal portion) rather than uniformly throughout the structure. The lattice structure is concentrated in the connecting portion where twisting resistance is most needed, while other areas maintain lighter construction, achieving local optimization of strength-to-weight ratio.
2Weight of moving object
If weight of connecting rod is reduced, then inertia force in reciprocating mass is reduced, but rigidity may be compromised
Solution Approach 1:
The connecting rod is segmented into functional zones with different structural characteristics: the connecting portion uses a lightweight lattice structure optimized for twisting resistance, while the longitudinal portion provides bending resistance with strategic reinforcing ribs. This segmentation allows weight reduction in non-critical areas while maintaining rigidity where needed.
Solution Approach 2:
The connecting rod employs a composite structural approach combining solid reinforcing ribs with lattice (truss-like) structures. This composite design achieves high strength-to-weight ratio by using material only where structurally necessary, reducing overall weight while maintaining or enhancing rigidity properties.
3Strength
If reinforcing ribs are added to ensure bending rigidity, then rigidity in bending direction is improved, but device complexity increases
Solution Approach 1:
The reinforcing structure is segmented into two distinct types: vertical reinforcing ribs for bending rigidity and oblique lattice structures for twisting resistance. This segmentation allows each structural element to be optimized for its specific function, achieving comprehensive rigidity without requiring a complex uniform structure throughout.
Solution Approach 2:
The lattice structure introduces a diagonal dimension to the traditionally vertical reinforcing rib configuration. By adding oblique members that cross between vertical ribs, the structure gains enhanced twisting resistance without significantly increasing complexity, as the lattice pattern follows natural load paths.
Data Source
AI summary
A engine connecting includes a large diameter end portion mounted to a crank of a crankshaft of an engine to be rotatable, a small diameter end portion into which a piston pin is inserted and which supports the piston pin to be rotatable, and a connecting portion connecting the large diameter end portion and the small diameter end portion at a longitudinal end portions thereof. The connecting portion has a plate-shape widened in a wide width direction thereof to be perpendicular to a center axis of the crank shaft, the connecting portion is provided with four vertical reinforcing portions projecting in four directions so as to extend in a longitudinal direction of the connecting rod from the small diameter end portion to the large diameter end portion.