Dual Link Engine Piston Offset Center of Gravity
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Solution Overview
Problem
Dual link internal combustion engines face issues with increased piston weight and vibration due to the addition of balance weights, leading to friction loss and noise, as well as collisions between the piston top end and the cylinder side wall, which are not effectively addressed by existing technologies.
Innovation Solution
The piston center of gravity is offset to one side by altering the piston crest surface unevenness, and the piston pin position is offset and inclined, allowing for reduced friction loss and noise while maintaining a predetermined mechanical compression ratio without increasing piston weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If a balance weight made of high specific gravity metal is cast in the piston to offset the center of gravity, then the piston's center of gravity position can be adjusted, but the piston weight increases and vibration worsens
Solution Approach 1:
The piston crest surface is designed with localized unevenness in specific areas (left or right side of the piston reciprocation line) to shift the center of gravity position. This approach adjusts the center of gravity by modifying the mass distribution in specific local regions rather than adding overall weight through balance weights, thereby resolving the contradiction between center of gravity control and piston weight reduction
Solution Approach 2:
The piston crest surface intentionally introduces asymmetric unevenness relative to the piston reciprocation line. By creating controlled asymmetry in the crest surface geometry, the center of gravity is shifted to the desired position without requiring symmetric balance weights, achieving center of gravity adjustment while minimizing additional weight and vibration
2Reliability
If the piston pin center axis is offset from the piston center line, then the piston orientation can be controlled to prevent collisions with the cylinder side wall, but the mechanical compression ratio becomes difficult to maintain
Solution Approach 1:
The invention offsets the piston pin center axis from the piston center line by a predetermined distance and inclines the piston pin at a specific angle. By changing these geometric parameters of the piston-crank mechanism, the piston orientation is controlled to prevent collisions with the cylinder side wall while the crest surface unevenness is designed to maintain the mechanical compression ratio, thereby resolving the contradiction between collision prevention and compression ratio maintenance
3Stability of the object's composition
If the link coupling center trajectory is positioned to one side of the piston reciprocation line, then the piston orientation is improved, but the combustion chamber capacity and compression ratio become difficult to control
Solution Approach 1:
The piston crest surface is designed with localized unevenness in specific areas relative to the piston reciprocation line. This local modification of the crest surface geometry allows the link coupling center trajectory to be positioned to one side for improved piston orientation stability, while the unevenness distribution is controlled to maintain the combustion chamber capacity and compression ratio at desired values
Data Source
AI summary
A dual link internal combustion engine, as viewed in a crank axial direction where a crankshaft rotates clockwise, has a following relative configuration. A piston pin center axis is offset to a right side of a piston center line extending through a center of a piston crest surface of a piston. A movement trajectory of a link coupling center of first and second links is positioned to a left side of a piston reciprocation line. A piston center of gravity is positioned to the left side. An average value of a distance in the cylinder axial direction to individual points of the piston crest surface from a reference plane passing through the piston pin center axis and orthogonal to the cylinder axial direction in an area to the left side is greater than an average value of the distance in an area to the right side.