Self-Lubricating Tribological Contact via Capillary Adhesion

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

In grease-lubricated or minimally oil-lubricated friction contacts, existing lubricant supply methods require active pumps and are limited by surface forces, leading to insufficient lubrication, increased wear, and higher manufacturing costs due to material and size constraints.

Innovation Solution

The relative movement between two contact bodies creates a lubricant path with microchannels and inlets/outlets, mimicking an active lubricant supply, ensuring efficient and loss-free lubrication, reducing wear and temperature, and allowing for smaller, lighter designs with lower material requirements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If active lubricant supply with pump is used, then sufficient lubrication is achieved, but device complexity and manufacturing costs increase

Engineering Contradiction:
Improvelubrication sufficiencyVSAvoidpump system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The lubricant path is designed to enable self-lubrication through the relative movement of contact bodies. The lubricant is transported passively along the lubricant path without external pumping, using the motion of the contact bodies themselves to drive lubricant delivery to the friction contact.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The active mechanical pump system is replaced by a passive lubricant transport mechanism that utilizes the relative movement and surface forces between contact bodies. This substitution eliminates the need for complex pumping machinery while maintaining sufficient lubrication.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Device complexity

If passive lubricant supply with surface forces is used, then device complexity is reduced, but lubrication efficiency decreases

Engineering Contradiction:
Improvelubricant supply system complexityVSAvoidlubrication efficiency
Core Design Contradiction:
Device complexityVSProductivity

Solution Approach 1:

The lubricant path is designed to dynamically adapt to the relative movement between contact bodies. The lubricant transport mechanism utilizes the dynamic motion of the contact bodies to actively deliver lubricant to the friction contact, transforming a static passive system into a dynamic efficient system.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system changes the state of lubricant transport from static passive delivery to dynamic movement-driven delivery. By utilizing the motion parameters of the contact bodies, the lubricant flow rate and delivery efficiency are enhanced while maintaining system simplicity.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If larger contact bodies are used, then temperature resistance and wear resistance improve, but weight and manufacturing costs increase

Engineering Contradiction:
Improvetemperature and wear resistanceVSAvoidcontact body weight
Core Design Contradiction:
ReliabilityVSWeight of moving object

Solution Approach 1:

The contact bodies are designed with self-lubricating capabilities through the integrated lubricant path. This self-service lubrication system reduces wear and thermal stress on the contact bodies, allowing them to maintain reliability without requiring excessive size or weight.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The effective contact area and lubrication parameters are optimized to achieve sufficient temperature and wear resistance without increasing the overall size of contact bodies. The improved lubricant delivery efficiency allows smaller, lighter components to achieve the same durability as larger traditionally-lubricated components.

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 friction, wear, and manufacturing costs while ensuring consistent lubrication, enhancing efficiency and service life, and allowing for the use of less expensive materials with lower temperature resistance.

Implementation Method 1

EP 2 508 778 A2 discloses a gear mounted on a pivot axis, preferably with a plurality of teeth arranged around its circumference for transmitting torque to a mating element interacting with the gear. A friction zone between a tooth and the mating element is provided with lubricant on a tooth flank surface. A longitudinal groove is formed on the tooth flank surface to supply the lubricant towards the friction zone. With this surface structure, the lubricant is directed to the friction contact by capillary action.

Methodology Applied
Scientific EffectCapillary action: Capillary Action

Implementation Method 2

the fluid column of lubricant arranged in the lubricant path, together with the lubricant adhering to the first contact body, forms a continuous fluid column. Thus, during the relative movement of the first contact body to the second contact body, the lubricant adhering to the first contact body can advantageously pull the fluid column arranged in the lubricant path along with it.

Methodology Applied
Scientific EffectAdhesion: Adhesive

Implementation Method 3

According to a further preferred embodiment, the surface of the second contact body is structured, at least in sections, to include at least one microchannel. By providing the microchannel in the surface of the second contact body, the flow of lubricant can be focused onto the frictional contact, or a Marangoni effect can be mitigated.

Methodology Applied
Scientific EffectMarangoni effect: Marangoni Effect

Data Source

PatentEP3242059B1Device with a tribological contact and method for operating a device comprising a tribological contact
Publication Date: 2020.03.04 ROBERT BOSCH GMBH
  • EP3242059B1 patent drawingFigure 1~2

AI summary

The invention relates to a device (1) with a frictional contact (10), wherein the frictional contact (10) can be supplied with lubricant (17) by a relative movement of a first contact body (12) to a second contact body (14), wherein a fluid column of lubricant (17) adhering to the first contact body (12) and arranged in the lubricant path (16) can be conveyed in the direction of the relative movement. The invention further relates to a method for operating a device (1) with a frictional contact (10).