Cam Follower Roller Grooves for Oil Retention and Low Friction

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Solution Overview

Problem

The manufacturing process of rollers for cam followers results in random traces on the lateral faces, leading to increased friction and oil leakage due to centrifugal effects, which hampers the operation and longevity of mechanical systems like injection pumps and valve actuators.

Innovation Solution

The method involves forming concentric circular grooves on the lateral faces of the roller during machining, reducing oil leakage and friction by improving the surface condition and lubrication.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If random traces are made on the lateral faces of the roller during grinding, then the manufacturing process is simple, but oil leakage increases and friction increases

Engineering Contradiction:
Improvegrinding process simplicityVSAvoidlubrication quality
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The invention applies a specific surface pattern (concentric circular grooves) only to the lateral faces of the roller that contact the tappet flanges. This localized modification improves oil retention and lubrication quality at the critical interface without affecting other parts of the roller, resolving the contradiction between simple manufacturing and reliable lubrication.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The invention changes the surface geometry parameter from random traces to controlled concentric circular grooves. This parameter change transforms the surface from one that promotes oil leakage to one that retains oil through centrifugal effect, improving lubrication quality while maintaining manufacturing feasibility through standardized machining processes.

Inventive Principle:
Principle #35Parameter changes

2Ease of manufacture

If random traces are made on the lateral faces of the roller, then the manufacturing process is straightforward, but friction at the interface increases

Engineering Contradiction:
Improvegrinding process simplicityVSAvoidfriction force
Core Design Contradiction:
Ease of manufactureVSForce

Solution Approach 1:

The concentric circular grooves are applied specifically to the lateral faces of the roller that contact the tappet flanges. This localized surface modification reduces friction at the critical sliding interface while maintaining the overall simplicity of the manufacturing process.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

By changing the surface geometry from random traces to controlled concentric grooves, the invention modifies the friction characteristics at the interface. The grooved surface reduces friction by improving oil film formation and distribution, while the manufacturing process remains straightforward.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If concentric circular grooves are formed on the lateral faces of the roller, then oil leakage is reduced and lubrication is improved, but the machining process becomes more complex

Engineering Contradiction:
Improvelubrication qualityVSAvoidmachining process complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The concentric circular grooves create a periodic surface pattern that effectively retains oil through centrifugal effect during roller rotation. This periodic structure improves lubrication quality by ensuring continuous oil supply to the contact interface, while the regular pattern can be efficiently produced by standardized machining operations.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The concentric circular groove pattern can be produced by copying a standard tool path or template during machining. This approach reduces the actual complexity of the machining process by using repeatable, standardized operations rather than requiring complex custom tooling or procedures.

Inventive Principle:
Principle #26Copying

4Reliability

If concentric circular grooves are formed on the lateral faces of the roller, then friction is reduced and functioning is improved, but the machining operation becomes more difficult

Engineering Contradiction:
Improvemechanical system functioningVSAvoidmachining ease
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The periodic concentric circular groove pattern improves mechanical system functioning by reducing friction through better lubrication. The regular, repeating nature of the grooves allows them to be efficiently produced by standardized machining operations, balancing performance improvement with manufacturing ease.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

By changing the surface geometry parameter from random traces to controlled concentric grooves, the invention reduces friction and improves functioning. The specific groove dimensions and spacing can be optimized to achieve the desired friction reduction while remaining within standard machining capabilities.

Inventive Principle:
Principle #35Parameter changes

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 reduces oil leakage and friction at the interface between the roller and tappet, enhancing the functioning and lifespan of mechanical systems by improving lubrication.

Implementation Method 1

the oil leakage by centrifugal effect along the lateral faces of the roller can be reduced

Methodology Applied
Scientific EffectCentrifugal force: Centrifugal Force

Data Source

PatentEP2944800B1Method for manufacturing a roller, adapted to equip a mechanical system forming a cam follower.
Publication Date: 2022.08.24 AB SKF SKF PATENT DEPARTMENT
  • EP2944800B1 patent drawingFigure 1~3
  • EP2944800B1 patent drawingFigure 4~5
  • EP2944800B1 patent drawingFigure 6~7

AI summary

The invention concerns a method for manufacturing a roller (40), adapted to equip a mechanical system forming a cam follower or a rocker arm, the roller (40) being centered on a central axis (X1) and comprising : an outer cylindrical surface (41) adapted to roll on a cam; an inner cylindrical bore (42) adapted to receive a pin (30) belonging to the mechanical system (1) ; and two lateral faces (43) extending radially to the central axis (X1). The method includes a machining step in which circular grooves (46) are formed concentric with each other on at least one of the lateral faces (43) of the roller (40). The invention also concerns a mechanical system comprising such a roller (40).