Polished Engine Liner with Thin DLC Coating
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Solution Overview
Problem
Existing solutions for reducing friction in internal combustion engine liners, such as DLC coatings and honing operations, are either ineffective or economically and technically challenging due to high coating thickness requirements and wear issues, leading to significant energy losses and CO2 emissions.
Innovation Solution
A manufacturing method that involves polishing the internal surface of the engine liner to achieve low roughness and applying a thin DLC coating without the need for honing, using techniques like tribofinishing and vacuum deposition to ensure adhesion and reduce friction and wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a DLC coating is applied to segments to reduce friction, then the coefficient of friction is reduced, but the coating thickness must be very high (>10 μm) which increases manufacturing complexity and cost
Solution Approach 1:
The patent replaces the conventional mechanical honing process with a chemical/physical DLC coating deposition process. Instead of mechanically removing material to create lubricant-retaining patterns, the invention deposits a diamond-like carbon coating that provides low friction without requiring subsequent mechanical finishing, thereby eliminating the need for high coating thickness and complex multi-step manufacturing.
Solution Approach 2:
The invention changes the surface preparation parameter from honing (mechanical removal creating peaks and valleys) to polishing (creating a smooth surface with Ra < 0.06 μm). This parameter change enables the DLC coating to achieve low friction with minimal thickness, as the smooth polished surface provides optimal adhesion and friction reduction without requiring thick coatings or subsequent honing to create lubricant reservoirs.
2Loss of energy
If a thick DLC coating (>10 μm) is applied to segments, then friction is reduced, but the roughness increases requiring recovery honing which adds manufacturing steps
Solution Approach 1:
The patent performs preliminary polishing of the segment surface before DLC coating deposition, creating a smooth surface (Ra < 0.06 μm) that enables thin coating application. This preliminary action eliminates the need for subsequent honing recovery steps that would be required after thick coating application, simplifying the manufacturing process to a single coating step without roughness recovery requirements.
3Reliability
If honing is performed on the liner to create lubricant retention patterns, then seizure risk is reduced, but oil film shearing losses increase
Solution Approach 1:
The patent replaces the mechanical honing process that creates lubricant-retaining peaks and valleys with a DLC coating deposition process on a polished surface. The DLC coating provides inherent low friction properties that prevent seizure without requiring thick oil films or mechanical surface patterns, thereby eliminating oil film shearing losses while maintaining seizure protection through the coating's tribological properties.
4Loss of energy
If the liner surface is burnished to reduce roughness, then friction is reduced, but work hardening occurs which causes cracking
Solution Approach 1:
The patent replaces the mechanical burnishing process that causes plastic deformation and work hardening with a polishing process followed by DLC coating deposition. The polishing process reduces surface roughness without causing work hardening or cracking, and the subsequent DLC coating provides the friction reduction that would otherwise require burnishing, thereby maintaining surface integrity while achieving low friction.
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 approach significantly reduces friction losses, maintains optimal sealing, and minimizes CO2 emissions by eliminating the honing step, while maintaining high engine performance over its life.
Implementation Method 1
applying a thin DLC coating without the need for honing, using techniques like tribofinishing and vacuum deposition to ensure adhesion and reduce friction and wear
Implementation Method 2
DLC type coatings (Diamond Like Carbon) on segments in order to lower the coefficient of friction of most metals
Data Source
AI summary
The invention relates to an internal combustion engine jacket, the inside of which is treated so as to be totally smooth and is provided with a DLC type coating.