Connecting Rod Eccentric Lever Arched Contour Wear Reduction
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Solution Overview
Problem
The existing connecting rod designs for internal combustion engines with adjustable compression ratios suffer from wear and tolerance issues due to deviations in the geometrical relationship between the eccentric rods and connecting pins, leading to high wear at the bearing location.
Innovation Solution
The aperture in the eccentric rod and the connecting pin are contoured with arched shapes, such as spherical or barrel shapes, to ensure a secure and tolerance-insensitive attachment, allowing for alignment and reducing wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cylindrical contours are used for the aperture in the eccentric rod and connecting pin, then the structure is simple and easy to manufacture, but deviations in geometrical relationship cause high wear at the bearing location
Solution Approach 1:
The patent applies spheroidality by replacing the cylindrical contour of the aperture and connecting pin with an arched contour. This curved geometry allows the connecting pin to automatically align with the aperture axis during assembly, compensating for manufacturing and assembly tolerances. The arched shape ensures that the axes of the eccentric rod and connecting pin are always at right angles, eliminating wear caused by misalignment while maintaining manufacturing feasibility through standard forming processes.
2Reliability
If precise geometrical relationship between eccentric rods and connecting pins is maintained, then wear is reduced, but manufacturing and assembly tolerances become difficult to accommodate
Solution Approach 1:
The arched contour design inherently compensates for tolerance variations. When the connecting pin is inserted into the aperture, the curved surfaces guide the pin into proper alignment, ensuring the axes are at right angles regardless of small manufacturing deviations. This self-aligning feature eliminates the need for high-precision manufacturing while preventing wear.
Solution Approach 2:
The patent changes the geometric parameter of the aperture and connecting pin from cylindrical to arched contour. This parameter change transforms the interaction between the components, allowing the curved surfaces to self-adjust and maintain the correct geometrical relationship (90-degree angle between axes) even when manufacturing tolerances cause slight variations in position or orientation.
Data Source
AI summary
A connecting rod (10) has a big end bearing eye (11) for attachment to a crankshaft and a small end bearing eye (12) for attachment to a piston of a cylinder. An eccentric adjusting device (13) adjusts an effective connecting rod length. The eccentric adjusting device (13) has eccentric rods (15, 16) that engage on an eccentric lever (14) of the eccentric adjusting device (13) so that, in the region of each eccentric rod (15, 16), a connecting pin (36) extends through apertures in the eccentric lever (14) and in the respective eccentric rod (15, 16). The aperture (37) in the respective eccentric rod (15, 16), through which the respective connecting pin (36) extends, and/or a section of the respective connecting pin (36) that extends through the aperture (37) in the respective eccentric rod (15, 16), has/have arched contours, at least in some section or sections.