Dual Eccentric Link Variable Compression Ratio Mechanism
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Solution Overview
Problem
Existing VCR apparatuses face issues with torsion during rotation due to their cantilever structure, which affects the distribution of load and increases costs due to the need for a guide member.
Innovation Solution
A VCR apparatus with dual eccentric links is designed, where eccentric links are symmetrically mounted on both sides of the connecting rod, distributing load uniformly and omitting the need for a guide member, thereby reducing torsion and costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a cantilever structure with guide member is used, then compression ratio adjustment is achieved, but torsion occurs and device complexity increases
Solution Approach 1:
The patent employs asymmetric positioning of the guide member relative to the crankshaft centerline, placing it on one side only. This asymmetric configuration, combined with the dual eccentric links rotating in opposite directions, creates a self-balancing system where the guide member directs the eccentric links without requiring symmetric support structures, thereby reducing overall structural complexity while maintaining compression ratio adjustability
Solution Approach 2:
The system divides the compression ratio adjustment function into two separate eccentric links that rotate in opposite directions. Each eccentric link independently controls one side of the connecting rod, segmenting the load path and allowing the guide member to manage only one side of the mechanism. This segmentation reduces the complexity compared to a single large eccentric mechanism would require
2Reliability
If dual eccentric links are used, then load balancing is improved, but device complexity increases
Solution Approach 1:
The dual eccentric links are configured to rotate in opposite directions, creating counterbalancing forces that offset each other. This anti-weight arrangement naturally balances the loads on the connecting rod without requiring additional counterweights or complex balancing mechanisms, achieving improved load distribution while keeping the structure relatively simple
Solution Approach 2:
The patent combines the functions of compression ratio adjustment and load balancing into a single dual eccentric link mechanism. The same two eccentric links that adjust the compression ratio also provide load balancing through their opposite rotation, merging multiple functions into one integrated system rather than requiring separate mechanisms for each function
3Adaptability or versatility
If guide member is included, then compression ratio control is achieved, but manufacturing cost increases
Solution Approach 1:
The patent extracts the guide function from a complex guided mechanism and implements it through a simple guide member that only needs to direct the eccentric links along a predetermined path. By separating the guiding function from the power transmission function, the guide member can be designed as a simple structural element rather than a complex mechanical component, reducing manufacturing costs while maintaining compression ratio control capability
Data Source
AI summary
A variable compression ratio (VCR) apparatus with dual eccentric links is mounted on an engine, receives combustion power of a fuel-air mixture from a piston to rotate a crank shaft and changes a compression ratio of the fuel-air mixture. The VCR apparatus may include a connecting rod having a large end portion formed at one end thereof, which is connected to the crank shaft to receive a torque of the engine, and a small end portion formed at the other end thereof, the small end portion having a coupling hole formed therein, a pair of eccentric links having one ends coupled to the coupling hole from both sides facing each other and integrally rotating, and an eccentric rod connected to the other ends of the eccentric links and rotating within a predetermined angle range. The eccentric rod may be a pair of eccentric rods.