Gear Lubrication Ring With Axial Ducts for Tooth Root Cooling

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Solution Overview

Problem

Existing gear lubrication systems for transmissions under heavy loads face challenges in providing continuous lubrication and cooling effectively, while also being costly and complex to manufacture and assemble.

Innovation Solution

The proposed arrangement involves a conduit system with axial discontinuities on the sun gear and the engaging ring, which guides and distributes lubricant under pressure to the roots of the gear teeth, enhancing lubrication and cooling efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If lubrication is effected intermittently by means of nozzles, then the structure is simple, but the lubrication effectiveness is insufficient for heavy load transmissions

Engineering Contradiction:
Improvelubrication effectivenessVSAvoidstructure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent implements continuous lubrication by providing a constant supply of lubricant under pressure through conduits directly to the gear tooth roots, eliminating the intermittent spray approach. The lubricant is continuously delivered along the entire length of the gear teeth via axial discontinuities, ensuring uninterrupted lubrication for heavy load conditions.

Inventive Principle:
Principle #20Continuity of useful action

Solution Approach 2:

The patent employs hydraulic principles by using lubricant under pressure delivered through conduits and ducts. The pressurized lubricant flows through axial discontinuities and recesses to reach the gear tooth roots, utilizing fluid pressure to ensure effective lubrication delivery to critical areas.

Inventive Principle:
Principle #29Pneumatics and hydraulics

2Temperature

If nozzle spray lubrication is used, then the device is simple to manufacture, but cooling effectiveness is insufficient

Engineering Contradiction:
Improvecooling effectivenessVSAvoidmanufacturing simplicity
Core Design Contradiction:
TemperatureVSEase of manufacture

Solution Approach 1:

The continuous flow of lubricant under pressure provides sustained cooling action. The lubricant is continuously supplied through conduits and distributed via axial discontinuities along the gear tooth roots, maintaining constant thermal management rather than intermittent cooling from spray nozzles.

Inventive Principle:
Principle #20Continuity of useful action

Solution Approach 2:

The patent extracts the cooling function from the lubrication system by directing lubricant flow specifically to the tooth roots where heat generation occurs. The axial discontinuities and recesses are designed to channel lubricant precisely to the root sections, separating the cooling function from general surface lubrication.

Inventive Principle:
Principle #2Taking out (Extraction)

3Reliability

If ring gear with internal splines is used, then lubrication to meshing teeth is improved, but manufacturing complexity increases

Engineering Contradiction:
Improvelubrication deliveryVSAvoidmanufacturing complexity
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent segments the lubrication delivery system into separate conduits and axial discontinuities that independently supply lubricant to each gear tooth root. This segmentation allows standard manufacturing processes for each component while achieving comprehensive lubrication coverage, avoiding the need for complex integrated spline structures.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces axial discontinuities and recesses as intermediary structures between the lubricant supply conduits and the gear tooth roots. These intermediaries distribute the lubricant flow to the critical root areas without requiring direct modification of the gear tooth geometry or creation of complex internal splines.

Inventive Principle:
Principle #24Intermediary (Mediator)

4Reliability

If ring gear with internal splines is used, then lubrication coverage is improved, but assembly complexity increases

Engineering Contradiction:
Improvelubrication coverageVSAvoidassembly complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The lubrication system is segmented into separate, modular components including conduits, axial discontinuities, and recesses that can be independently manufactured and assembled. This modularity simplifies assembly compared to integrated spline structures, allowing each component to be fitted separately while achieving complete lubrication coverage.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The axial discontinuities serve multiple functions: they guide lubricant flow, create recesses for lubricant distribution, and provide structural integration with the gear body. This multi-functionality reduces the need for separate components, simplifying assembly while maintaining comprehensive lubrication coverage.

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

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 solution reduces manufacturing complexity and cost by minimizing machining requirements, while ensuring effective lubrication and cooling of gear teeth under heavy loads, thus improving the overall performance and reliability of the transmission.

Implementation Method 1

at least one conduit (532) arranged to guide lubricant under pressure from the central duct (531) radially outwards to the peripheral surface (535)

Methodology Applied
Scientific EffectPressure gradient: Pressure Gradient

Data Source

PatentEP4119817B1Arrangement for lubricating a gear
Publication Date: 2025.01.29 VOLVO TRUCK CORP
  • EP4119817B1 patent drawingFigure 1
  • EP4119817B1 patent drawingFigure 2
  • EP4119817B1 patent drawingFigure 3A~3B

AI summary

The invention relates to an arrangement for lubricating a gear (503; 603; 703; 803) in a toothed gearing comprising a shaft (501; 601; 701; 801) on which the gear (503; 603; 703; 803) is arranged. An engaging ring (502; 602; 702; 802) with a central portion (512; 612; 712; 812) is arranged around said shaft (501; 601; 701; 801) and comprises a surface (526; 626; 726; 826) facing and spaced from an end surface (527; 627; 727; 827) of the gear (503; 603; 703; 803) creating a gap (533; 633; 733; 833) for guiding lubricant to the gear, and at least one first duct (531, 532; 525; 631, 632; 625; 731, 732; 725; 831, 832; 825) for lubricant, whereby said duct has at least one opening into the gap (533; 633; 733; 833). The component comprises an annular portion (528; 628; 728; 828) with an inner peripheral surface mounted onto an outer peripheral surface of a shoulder (530; 630; 730; 830) on the gear; where axial discontinuities (534; 634; 734; 834) are provided between the shoulder (530; 630; 730; 830) and the annular portion of the component for guiding and distributing lubricant to the roots of the gear (503; 603; 703; 803).