Multi-link Engine Cylinder Liner Cutout Geometry
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Solution Overview
Problem
The rigidity of the cylinder liner is weakened by forming a cutout at the bottom end, leading to potential deformation and degradation of the contact state between the cylinder liner and piston skirt under high thrust loads in multi-link engines.
Innovation Solution
A multi-link engine design with a variable bottom end position of the cylinder liner and specific link geometry where the upper link forms an angle with the cylinder axis, minimizing thrust force on the cylinder liner, thereby preventing deformation and maintaining lubrication film integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a cutout is formed in the bottom end of the cylinder liner to enable longer stroke without increasing overall height, then the stroke length is improved, but the rigidity of the cylinder liner is weakened
Solution Approach 1:
The patent applies local quality by making the bottom end position of the cylinder liner variable rather than uniform. Specifically, different portions of the bottom end have different positions, with cutouts strategically placed to allow longer stroke while maintaining rigidity in critical areas. This localized variation in structure allows the cylinder liner to have both reduced overall height and adequate rigidity where needed.
2Length of stationary object
If a cutout is formed in the bottom end of the cylinder liner, then the overall height is reduced, but the surface pressure on the cylinder liner increases
Solution Approach 1:
The patent addresses this contradiction by creating a variable bottom end structure where cutouts are strategically positioned to reduce overall height while maintaining sufficient surface area in load-bearing regions. The non-uniform bottom end design ensures that high-pressure areas retain adequate contact surface, preventing excessive surface pressure despite the height reduction.
3Length of moving object
If the rigidity of the cylinder liner is weakened by forming cutouts, then the engine can achieve longer stroke, but the contact state between cylinder liner and piston skirt degrades
Solution Approach 1:
The patent resolves this contradiction by ensuring that the variable bottom end structure maintains adequate contact surface in the region where the piston skirt interacts with the cylinder liner. The cutouts are positioned and sized such that they enable longer stroke while preserving the necessary contact area and quality for reliable piston-cylinder interaction, preventing degradation of the contact state.
Data Source
AI summary
A multi-link engine has a piston coupled to a crankshaft to move inside an engine cylinder. A piston pin connects the piston to an upper link, which is connected to a lower link by an upper link pin. A crank pin of the crankshaft rotatably supports the lower link thereon. A control link pin connects the lower link to one end of a control link, which is connected at another end to the engine block body by a control shaft. The upper link has an upper link axis that forms an angle with the cylinder axis, as viewed along a crank axis direction of the crankshaft, such that the angle reaches a minimum when a crank angle of the engine is within a range where the bottom end of a piston skirt is positioned below a topmost part of the bottom end of the cylinder liner.