DLC-Coated Tappet Pin Oil Screening by Friction Signal
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Solution Overview
Problem
DLC coatings on tappet pins in combustion engines are vulnerable to certain lubricant oils, leading to premature wear and increased maintenance costs due to difficulty in predicting the adverse effects of oil additives on the coating's longevity.
Innovation Solution
A method involving an oil selection test using an oil cup and reciprocating actuator to measure friction force signals between a DLC coated tappet pin and a static member, rejecting oils that cause a significant drop in friction signal, indicating coating instability, and selecting oils that maintain adequate friction for extended tappet pin life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If DLC coating is applied to tappet pin to increase wear resistance, then the tappet pin can endure more revolutions, but the coating becomes vulnerable to certain lubricant oils containing additives
Solution Approach 1:
The patent applies preliminary action by conducting a friction measurement test before actual engine operation to predict the compatibility between DLC coating and lubricant oil. The test measures friction force signals in advance to identify oils that would cause coating degradation, allowing selection of suitable lubricants before the tappet pin is installed in the engine.
Solution Approach 2:
The patent employs feedback by measuring the friction force signal during the test and using this measurement to determine oil compatibility. The friction signal serves as feedback information that indicates whether the lubricant oil is suitable for the DLC coated tappet pin, with specific patterns in the friction signal revealing potential coating degradation issues.
2Force
If friction reducing additives are added to lubricant oil to minimize friction, then friction in sliding contact is reduced, but the DLC coating is weakened and requires premature replacement
Solution Approach 1:
The patent performs a preliminary friction measurement test to identify lubricant oils that cause excessive friction reduction and subsequent coating degradation. By measuring the friction force signal in advance, the test predicts which oils will prematurely wear the DLC coating, allowing selection of oils that maintain appropriate friction levels for coating protection.
Solution Approach 2:
The friction force measurement serves as feedback to evaluate the interaction between lubricant additives and DLC coating. The test detects when friction reducing additives cause harmful effects on the coating, providing feedback information to select lubricants with appropriate additive packages that protect rather than degrade the coating.
3Measurement precision
If chemical analysis or manufacturer information is used to detect Mo compounds in oil, then presence of additives can be identified, but it is difficult to estimate the adverse effect on coating longevity due to varying additive amounts
Solution Approach 1:
The patent replaces chemical analysis methods with a mechanical measurement approach. Instead of using chemical analysis or relying on manufacturer information to assess oil compatibility, the invention uses friction force measurement during reciprocating motion to directly evaluate the effect of lubricant additives on DLC coating performance.
Solution Approach 2:
The patent changes the measurement parameter from chemical composition analysis to friction force measurement. By measuring the friction force signal during reciprocating motion, the test directly assesses the mechanical effect of lubricant additives on the coating, providing a more accurate prediction of coating longevity than chemical analysis alone.
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 method efficiently and reproducibly selects suitable engine oils for DLC coated tappet pins, reducing maintenance costs by identifying oils that minimize friction and extend the tappet pin's lifespan by ensuring stable DLC coating performance.
Implementation Method 1
measuring a friction force signal of the oil cup relative to the holder substrate
Data Source
Figure 1
Figure 2
Figure 3~3B
AI summary
According to the invention, a method of lubricating a DLC coated tappet pin in a combustion engine, comprising providing an oil cup on a holder substrate, said cup having a static member mounted therein immersed in an oil under selection; mounting the tappet pin to a distal end part of a reciprocating actuator; applying a downward force to establish a contact pressure between the tappet pin and the static member, while actuating the tappet pin, by the actuator, in reciprocating motion over the static pin, the static member oriented transverse to the tappet pin; measuring a friction force signal of the oil cup relative to the holder substrate in a predetermined time frame; and rejecting the oil under selection for lubricating the tappet pin in the engine, when a friction signal drops below a threshold level in the predetermined time frame; or else selecting the oil under selection to lubricate the tappet pin in the engine.