Friction Part Groove Pattern for Oil Film Removal

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Solution Overview

Problem

Existing friction parts for friction-locking devices, such as multi-plate clutches and disk brakes, face challenges in achieving rapid oil film removal, inadequate cooling, high drag torque, and difficult assembly due to alignment requirements.

Innovation Solution

A friction part with an annular friction surface featuring a set of grooves, including a first groove extending to a bifurcation point and second and third grooves extending from the bifurcation point, where at least one of the second or third grooves is a blind groove, facilitating easy assembly and reducing drag torque by controlling pressure and enhancing cooling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If conventional groove patterns are used in friction surfaces, then the structure is simple, but the oil film removal speed is insufficient and cooling is inadequate

Engineering Contradiction:
Improveoil film removal speedVSAvoidgroove pattern complexity
Core Design Contradiction:
SpeedVSDevice complexity

Solution Approach 1:

The groove pattern is segmented into multiple functional zones: radial grooves for oil supply, circumferential grooves for oil film removal, and diagonal grooves for pressure distribution. This segmentation allows each groove type to perform its specific function optimally, achieving rapid oil film removal while maintaining a systematic rather than overly complex structure.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The groove pattern extends into multiple dimensional orientations (radial, circumferential, and diagonal directions) rather than using simple single-direction grooves. This multi-dimensional groove arrangement enhances oil flow paths and pressure distribution, significantly improving oil film removal speed and cooling efficiency.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Temperature

If high oil pressure is applied to the friction surface, then cooling is enhanced, but the friction lining may be damaged

Engineering Contradiction:
Improvefriction surface coolingVSAvoidfriction lining integrity
Core Design Contradiction:
TemperatureVSStrength

Solution Approach 1:

Different groove regions provide different local functions: radial grooves supply oil under pressure to areas requiring cooling, while circumferential and diagonal grooves distribute and reduce pressure in areas where the friction lining is vulnerable. This local differentiation allows high pressure where needed for cooling while protecting the friction lining from damage.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The groove pattern acts as an intermediary system that mediates between the high-pressure oil supply and the friction lining. The multi-directional grooves distribute and regulate oil pressure, allowing effective cooling to be achieved without transmitting damaging peak pressures directly to the friction lining.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Loss of energy

If grooves extend continuously from inner edge to outer edge, then oil flow is straightforward, but drag torque is not reduced sufficiently

Engineering Contradiction:
Improvedrag torque reductionVSAvoidgroove configuration complexity
Core Design Contradiction:
Loss of energyVSDevice complexity

Solution Approach 1:

Continuous grooves are segmented into multiple sections with different orientations (radial, circumferential, diagonal). The circumferential and diagonal segments specifically contribute to drag torque reduction by creating pressure zones that push friction plates apart during engagement, while the radial segments maintain straightforward oil flow paths.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The groove pattern achieves multiple functions simultaneously: radial grooves provide oil supply, circumferential grooves remove oil film and reduce drag torque, and diagonal grooves distribute pressure. This multi-functionality allows drag torque reduction without requiring separate dedicated structures, maintaining reasonable complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

4Speed

If alignment of grooves with direction of rotation is required, then oil film removal is optimized, but assembly becomes difficult

Engineering Contradiction:
Improveoil film removal efficiencyVSAvoidassembly ease
Core Design Contradiction:
SpeedVSEase of manufacture

Solution Approach 1:

The groove pattern incorporates asymmetric diagonal grooves at specific angles (15-45 degrees) relative to the radial direction. This asymmetric design optimizes oil film removal in the direction of rotation while the overall symmetric arrangement of multiple groove sets ensures that the friction part can be assembled without precise alignment, as the pattern works effectively in both rotational directions.

Inventive Principle:
Principle #4Asymmetry

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 enables rapid oil film removal, effective cooling, reduced drag torque, and simplified assembly, ensuring smooth engagement regardless of oil volume, pressure, or temperature, while preventing friction lining damage.

Implementation Method 1

adequate cooling of the friction lining or the friction surface by the oil flowing through the grooves

Methodology Applied
Scientific EffectConvection: Convection

Implementation Method 2

During operation, at this deflection point there is a selective pressure increase in the coolant flowing through, such as oil, as a result of which adjacent plates of the multi-plate clutch are pressed apart

Methodology Applied
Scientific EffectPressure increase: Pressure Increase

Implementation Method 3

a friction part for a friction-locking device with an annular friction surface

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP2162627B1Friction part for a frictionally working device
Publication Date: 2011.12.21 BORGWARNER INC
  • EP2162627B1 patent drawingFigure 1
  • EP2162627B1 patent drawingFigure 2~5
  • EP2162627B1 patent drawingFigure 6

AI summary

The present invention relates to a friction part (2) for a frictionally working device with a ring-shaped friction surface (22) which has an inner edge (24) and an outer edge (26). In the friction surface (22), at least one set of grooves (28) with a first groove (36), which extends from the inner edge (24) or the outer edge (26) to a branching point (28) between the inner edge (24) and the outer edge (26), is provided, and a second and third groove (44, 46), each of which extends from the branching point (38) in the direction of the other edge (26, 24), is provided. According to the invention, at least one of the second and third grooves (44, 46) is constructed as a blind groove, while the other groove (46, 44) extends continuously up to the other edge (26, 24), and/or at least a fourth groove is provided, which extends from the branching point in the direction of the other edge and is constructed as a blind groove.