Roller Rocker Arm Dimpled Oil Reservoirs

Solution Overview

Problem

Conventional rocker arm-type valve mechanisms in internal combustion engines face challenges with friction performance and scuffing resistance due to boundary lubrication, which limits the effectiveness of lubricating oil distribution and leads to increased wear and friction.

Innovation Solution

The implementation of dimple-shaped oil reservoirs on the sliding surfaces of the rocker arm components, such as the roller shaft and rollers, enhances lubricating oil retention and utilization, transitioning from boundary lubrication to fluid lubrication, thereby improving friction performance and scuffing resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a sliding-type rocker arm with clearances between sliding surfaces is used, then ease of assembly and tolerance compensation are improved, but friction performance and scuffing resistance deteriorate due to boundary lubrication

Engineering Contradiction:

Improveease of assemblyVSAvoidfriction performance

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The invention applies local quality by creating dimples only at specific contact regions (sliding surfaces) where lubrication is most needed, rather than modifying the entire component. These localized dimples on the roller shaft and rollers improve lubrication exactly where boundary lubrication causes problems, while maintaining the overall clearance design for ease of assembly.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The dimpled surfaces create a micro-porous structure that acts as an oil reservoir, allowing lubricating oil to be retained and supplied continuously to the sliding surfaces. This porous-like structure transforms the lubrication regime from boundary lubrication to fluid lubrication, improving friction performance and scuffing resistance while maintaining the clearance-based assembly ease.

Inventive Principle:

Principle #31Porous materials

2Volume of moving object

If rolling elements with small outer diameter are used, then compactness and space utilization are improved, but contact pressure increases due to line-contact according to Hertz's contact theory

Engineering Contradiction:

ImprovecompactnessVSAvoidcontact pressure

Core Design Contradiction:

Volume of moving objectVSStress or pressure

Solution Approach 1:

The invention applies local quality by creating dimples only at specific contact regions (sliding surfaces) where lubrication is most needed, rather than modifying the entire component. These localized dimples on the roller shaft and rollers improve lubrication exactly where boundary lubrication causes problems, while maintaining the overall clearance design for ease of assembly.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The dimpled surfaces create a micro-porous structure that acts as an oil reservoir, allowing lubricating oil to be retained and supplied continuously to the sliding surfaces. This porous-like structure transforms the lubrication regime from boundary lubrication to fluid lubrication, improving friction performance and scuffing resistance while maintaining the clearance-based assembly ease.

Inventive Principle:

Principle #31Porous materials

3Reliability

If lubricating oil supply to sliding surfaces is increased, then friction performance improves, but device complexity and oil distribution system complexity increase

Engineering Contradiction:

Improvefriction performanceVSAvoidoil distribution system complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The dimpled surfaces enable the sliding surfaces to serve themselves by retaining and supplying their own lubricating oil through the dimple reservoirs. This self-service mechanism eliminates the need for complex external oil distribution systems, as the lubrication is provided locally by the dimples themselves, reducing system complexity while improving friction performance.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The dimples act as an intermediary structure between the lubricating oil supply system and the sliding surfaces. Instead of requiring a complex direct supply system, the dimples mediate by capturing and delivering oil locally, simplifying the overall oil distribution system while ensuring adequate lubrication.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 use of dimple-shaped oil reservoirs results in a significant reduction in friction loss and improved scuffing resistance, with measured improvements of around 3-5% in friction loss and scuffing resistance compared to conventional designs, ensuring smoother operation and longer lifespan of the rocker arm.

Implementation Method 1

a plurality of dimples 150 are provided on at least one of sliding surfaces of the rocker arm components, so that lubricating oil is remained in the dimple 150

Methodology Applied

Scientific EffectCapillary action: Capillary Action

Data Source

PatentUS10119428B2Roller type rocker arm

Publication Date: 2018.11.06 RIKEN CO LTD

AI summary

A roller-type rocker arm includes a roller shaft. A sliding surface of an outer circumference surface of the roller shaft includes a number of dimples. An inner ring roller is slidably attached to the outer circumference surface of the roller shaft. An inner circumference surface and an outer circumference surface of the inner ring roller include a number of dimples. An outer ring roller is slidably attached to the outer circumference surface of the inner ring roller. An inner circumference surface of the outer ring roller includes a number of dimples.