Hydrodynamic Bearing Pocket Layout for Low-Loss Stable Gearboxes

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Solution Overview

Problem

Existing hydrodynamic bearings in high-speed, high-power gearboxes face challenges in achieving low power losses, dynamic stability, and reliability, especially under varying load conditions and high journal velocities.

Innovation Solution

A hydrodynamic bearing design featuring a first injection pocket in the unloaded sliding surface and a second injection pocket in the loaded sliding surface, both with radial recesses that define the active areas and optimize fluid flow, reducing power losses and enhancing dynamic stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If large axial pockets are provided over the whole length of the bearing, then power losses are reduced at full load and no load, but dynamic stability issues arise during startup and high pressures and temperatures occur at full load

Engineering Contradiction:

Improvepower lossesVSAvoiddynamic stability

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The bearing surface is segmented into multiple zones with different functions: an unloaded sliding surface with a first injection pocket for low power loss, and a loaded sliding surface with a second injection pocket for stability. This segmentation allows each zone to be optimized for its specific purpose, resolving the contradiction between power loss reduction and dynamic stability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the bearing are given different properties: the unloaded sliding surface is optimized for minimizing friction and power loss, while the loaded sliding surface is optimized for maintaining dynamic stability and controlling pressure. The injection pockets are strategically positioned in each region to provide localized fluid supply where needed, creating local quality variations that resolve the contradiction.

Inventive Principle:

Principle #3Local quality

2Loss of energy

If small axial pockets with radial recesses are provided mainly limited to the unloaded sliding surface, then power losses are reduced at full load, but power losses at no load cannot be prevented effectively and dynamic stability optimization potential remains

Engineering Contradiction:

Improvepower losses at full loadVSAvoidoptimization potential for no load and dynamic stability

Core Design Contradiction:

Loss of energyVSAdaptability or versatility

Solution Approach 1:

The bearing design incorporates two injection pockets that serve multiple functions: the first injection pocket in the unloaded sliding surface minimizes power losses, while the second injection pocket in the loaded sliding surface provides dynamic stability. This multi-functional approach allows the bearing to effectively address both no-load power loss and dynamic stability requirements simultaneously.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Power

If high journal velocity is maintained for high power output, then power loss increases proportionally to velocity cubed, but reducing velocity decreases power output

Engineering Contradiction:

Improvepower outputVSAvoidpower loss

Core Design Contradiction:

PowerVSLoss of energy

Solution Approach 1:

The patent uses hydraulic injection of fluid through strategically positioned injection pockets to reduce friction and power losses in the bearing. By injecting fluid at specific locations (unloaded and loaded sliding surfaces), the system maintains high journal velocity for power output while minimizing the velocity-cubed power loss through improved lubrication.

Inventive Principle:

Principle #29Pneumatics and hydraulics

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 design achieves low power losses and high dynamic stability, ensuring efficient operation under both no-load and full-load conditions, while minimizing maximum pressure and temperature, thus improving the reliability of the bearing.

Implementation Method 1

The functioning and the bearing characteristics is/are dependent on lubrication and injection of fluid between the bearing surface and the rotating element (shaft)

Methodology Applied

Scientific EffectHydrodynamic lubrication: Lubrication

Data Source

PatentUS12264707B2Hydrodynamic bearing for supporting a rotating element, gearbox accommodating such a hydrodynamic bearing, and use of such a hydrodynamic bearing

Publication Date: 2025.04.01 FLENDER GRAFFENSTADEN SA

AI summary

A hydrodynamic bearing for accommodating and supporting a rotating element includes an unloaded sliding surface, a loaded sliding surface downstream of the unloaded sliding surface, a first injection pocket arranged within the unloaded sliding surface and a second injection pocket arranged within the loaded sliding surface. A radial recess arranged within the unloaded sliding surface and the loaded sliding surface extends in a circumferential direction such as to overlap the first and second injection pockets in the circumferential direction upstream and downstream. The radial recess defines or delimits an active area of the unloaded and loaded sliding surfaces. Each of the first and second injection pockets has an axial length which is smaller than an axial extension of the active area upstream or downstream in a corresponding circumferential sliding section of the unloaded sliding surface and loaded sliding surface in which the first and second injection pockets respectively are arranged.