Multi-link Piston Crank Oil Reflection for Cylinder Lubrication
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Solution Overview
Problem
In multi-link piston-crank mechanisms, existing designs face challenges in directing lubricating oil to the cylinder inside wall surface on the side where the control link is located, especially when the crank pin is offset, making it difficult to align the oil guide groove radially with the cylinder inside wall surface without considering the swing posture of the lower link.
Innovation Solution
The mechanism incorporates a lower link oil passage that communicates with the crank pin oil passage at a predetermined swing posture, ejecting lubricating oil towards the upper link, which then reflects and directs it to the cylinder inside wall surface on the control link's side, ensuring effective lubrication and preventing scuffing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the crank pin is offset to the other side beyond the cylinder inside wall surface on the control link's side, then the multi-link piston-crank mechanism can be configured with the first connecting pin on one side of the cylinder center axial line and the second connecting pin on the other side, but it becomes difficult to align the oil guide groove radially with the cylinder inside wall surface on the control link's side without regard to the swing posture of the lower link
Solution Approach 1:
The upper link serves as an intermediary to redirect the lubricating oil. The lower link oil passage ejects oil toward the upper link, which then reflects and directs it to the cylinder inside wall surface on the control link's side, bypassing the alignment issue caused by crank pin offset
Solution Approach 2:
Instead of directing oil directly from the lower link to the cylinder wall (which requires radial alignment), the invention inverts the path by ejecting oil toward the upper link first, which then redirects it to the target surface, eliminating the need for direct radial alignment
2Reliability
If an oil guide groove is formed in the lower link to supply lubricating oil directly to the cylinder inside wall surface, then lubrication can be provided, but the direction of the oil guide groove cannot be set toward the cylinder inside wall surface on the control link's side without regard to the swing posture of the lower link
Solution Approach 1:
The upper link acts as a mediator that receives lubricating oil from the lower link oil passage and redirects it to the cylinder inside wall surface on the control link's side, ensuring reliable lubrication supply independent of lower link swing posture
Solution Approach 2:
The invention uses the dynamic movement of the upper link to redirect the oil flow. As the upper link moves and reflects the oil jet, it adaptively directs lubrication to the cylinder wall regardless of the lower link's swing posture, providing swing posture independence
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution allows for targeted lubrication of the cylinder inside wall surface, effectively preventing piston scuffing by directing lubricating oil to the area receiving thrust pressure, even when the crank pin is offset, and is cost-effective compared to other arrangements.
Implementation Method 1
the upper link is arranged to reflect or throw back the lubricating oil ejected from the lower link oil passage and thereby to supply or direct the lubricating oil to a cylinder inside wall surface on a side on which the control link is located
Data Source
Figure 1
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AI summary
When the compression ratio of a variable compression ratio internal combustion engine (10) is set at a low compression ratio, a lubricating oil ejected from a lower link oil passage (25) is reflected by an upper link (11) at the piston top dead center, and supplied to a cylinder inside wall surface on the side on which a control link (15) is located in a view as viewed in the axial direction of the crank shaft. When the compression ratio of the variable compression ratio internal combustion engine (10) is set at a high compression ratio, the lubricating oil ejected from lower link oil passage (25) is reflected by upper link (11) at the piston top dead center, and supplied to the back side of the piston crown.