Timing Chain Link Plate Coating for Low-Friction Guide Contact
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Solution Overview
Problem
In chain transmission devices, particularly in timing chains, the small contact area between the link plates and the chain guide leads to increased friction loss due to boundary lubrication when using low-viscosity lubricating oils, causing instability and reduced fuel efficiency.
Innovation Solution
A chain transmission device with link plates having a convex portion on their back surfaces, coated with a chromium-containing film, which reduces the contact area with the chain guide to 50% or less, and uses a molybdenum compound friction modifier in the lubricating oil to maintain low friction even in boundary lubrication conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the contact area between the link plate back surface and the chain guide is reduced to reduce frictional resistance, then friction loss decreases in fluid lubrication, but boundary lubrication occurs more easily with low-viscosity oils causing friction loss to increase
Solution Approach 1:
The invention applies a chromium-containing coating film specifically to the link plate back surface that contacts the chain guide, creating a localized region with different friction characteristics. This coating provides a low-friction surface that maintains stable lubrication even in boundary lubrication conditions, resolving the contradiction by improving the local quality of the contact surface without changing the overall contact area geometry
Solution Approach 2:
The invention uses a composite structure combining the base link plate material with a chromium-containing coating film. This composite material approach allows the link plate to maintain its structural integrity while the coating layer provides enhanced lubrication properties, preventing friction loss increase in boundary lubrication conditions
2Loss of energy
If a chromium-containing coating film is applied to the link plate back surface to maintain low friction in boundary lubrication, then friction loss is controlled, but manufacturing complexity increases
Solution Approach 1:
The invention specifies quantitative parameters for the chromium coating: chromium content of 10% or more by weight, and coating thickness of 3 μm or more. These parameter specifications ensure effective friction reduction while providing clear manufacturing targets, balancing performance improvement with manufacturing feasibility
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
The solution significantly reduces friction loss in both fluid and boundary lubrication regions, enhancing the stability and durability of the chain transmission device while maintaining low friction coefficients, thus improving fuel efficiency and reducing wear.
Implementation Method 1
the contact area between the back surface of the link plate and the chain guide is small to reduce a frictional resistance, and in which an increase in the frictional resistance is prevented even in boundary lubrication by matching a friction modifier added to a lubricating oil with a material of the link plate
Data Source
AI summary
When a contact area with a chain guide is reduced by a back surface of a link plate having a convex portion, a friction coefficient in a fluid lubrication region is reduced. A coating film containing 10% or more of chromium is on the link plate. A friction modifier made of a molybdenum compound and including with a lubricating oil promotes generation of MoS2 by the coating film, and prevents an increase in a friction coefficient in a boundary lubrication region.