Piston Skirt Resin Layer for Engine Thermal Management
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Solution Overview
Problem
The existing internal combustion engines with a diamond-like carbon layer on the piston ring face issues due to an inappropriate gap between the piston skirt and the cylinder wall, leading to noise, abrasion, or cohesion, especially when the engine is started without warming up, causing temperature differences that affect the piston's shape and performance.
Innovation Solution
The engine incorporates a resin layer on the slidable portion of the piston skirt, which prevents heat transmission to the cylinder wall, maintaining heat preservability and reducing temperature differences between the piston head and skirt, thus ensuring an appropriate gap size and minimizing noise and wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a diamond-like carbon layer is provided on the outer circumference of the piston ring to prevent cylinder wall scuffing, then the cylinder wall protection is improved, but the heat release from the piston to the cylinder wall is reduced, causing large temperature difference between piston head and piston skirt
Solution Approach 1:
The invention applies different thermal insulation properties to different parts of the piston: the piston ring retains the diamond-like carbon layer for protection, while the piston skirt receives a resin layer coating for thermal insulation. This local differentiation allows each component to have optimized properties for its specific function.
Solution Approach 2:
The invention uses composite material structures: the piston ring combines metal substrate with diamond-like carbon coating, while the piston skirt uses metal substrate with resin layer coating. These composite structures provide both mechanical strength and specialized surface properties for each component.
2Reliability
If the temperature difference between piston head and piston skirt is large due to heat insulation, then the piston ring protection is improved, but the piston deformation is reduced, causing the gap between piston skirt and cylinder wall to be inappropriate
Solution Approach 1:
The resin layer is applied specifically to the piston skirt's outer peripheral surface where it contacts the cylinder wall, creating local thermal insulation precisely where needed to control the gap formation and maintain appropriate clearance during operation.
3Device complexity
If the gap between piston skirt and cylinder wall is not appropriate due to temperature difference, then the piston ring structure is simplified, but the piston support function is reduced, causing noise and collision
Solution Approach 1:
The resin layer acts as an intermediary between the piston skirt and the cylinder wall, providing thermal insulation that maintains appropriate temperature and gap conditions, thereby preventing direct harmful contact and reducing noise and collision.
4Loss of time
If the engine is started without warming up, then the startup time is reduced, but the temperature difference causes inappropriate gap size, leading to noise, abrasion, or cohesion
Solution Approach 1:
The resin layer is pre-applied to the piston skirt before engine operation, creating a permanent thermal insulation structure that automatically compensates for temperature differences during cold startup, eliminating the need for extended warming-up procedures.
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 effectively reduces noise and prevents abrasion or cohesion by maintaining a stable temperature distribution in the piston, ensuring the gap between the piston skirt and cylinder wall is appropriate soon after engine start-up, even when the engine is cold.
Implementation Method 1
the slidable portion of the piston skirt includes a resin layer in at least a part thereof, the resin layer preventing the heat of the piston from being transmitted from the piston skirt to the cylinder wall
Implementation Method 2
the piston ring includes an outer circumference coming into contact with the cylinder wall to transmit heat of the piston to the cylinder wall
Data Source
Figure 1
Figure 2(a)~2(d)
Figure 3~5(b)
AI summary
An obj ect is to suppress a problem caused to an internal combustion engine, including a diamond-like carbon layer provided on an outer circumference of a piston ring, due to a gap between a piston skirt and a cylinder wall not having an appropriate size. A piston included in an internal combustion engine in an embodiment according to the present invention includes a piston head; a piston ring attached to an outer circumference of the piston head; and a piston skirt extending along the cylinder wall from the outer circumference of the piston head. The piston ring includes a diamond-like carbon layer on an outer circumference thereof. The piston skirt includes a slidable portion slidable against the cylinder wall. The slidable portion includes a resin layer in at least a part thereof, the resin layer preventing heat of the piston from being transmitted from the piston skirt to the cylinder wall.