Aircraft Reduction Gear Hydrodynamic Abutment for Sun Gear Axial Support
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Solution Overview
Problem
Existing mechanical reduction gears in turbine engines face challenges in maintaining the axial position of the sun gear while allowing radial freedom to prevent hyperstatic effects, often requiring large axial bearings that are not optimal in size or efficiency.
Innovation Solution
A hydrodynamic abutment is introduced, where the sun gear bears axially on a bearing surface with an oil film interposed, allowing axial positioning and force absorption without restricting radial movement, and the lubrication circuit supplies oil to form this film, maintaining the sun gear's axial position without increasing the gear's axial dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a ball bearing is used to guide the sun gear axially, then the axial forces are taken up, but the axial dimensions of the reduction gear increase significantly
Solution Approach 1:
The patent replaces the traditional mechanical ball bearing system with a hydrodynamic bearing system that uses a film of lubricating oil to support the sun gear axially. The lubrication circuit conveys oil onto the bearing surface to form this film, substituting solid mechanical contact with fluid dynamic support, thereby eliminating the need for large axial dimensions while maintaining force absorption capability
Solution Approach 2:
The invention applies hydraulic principles by using a lubrication circuit to deliver lubricating oil to the bearing surface, creating a hydrodynamic film that supports the sun gear. This hydraulic approach allows axial force absorption through fluid pressure and viscosity rather than mechanical contact, resolving the contradiction between force support and compact axial dimensions
2Stability of the object's composition
If the sun gear is constrained axially, then axial movement is prevented, but radial freedom is restricted causing hyperstatic effects
Solution Approach 1:
The patent introduces a lubricating oil film as an intermediary between the sun gear and the bearing surface. This fluid mediator allows the sun gear to maintain stable axial positioning through the hydrodynamic support while simultaneously permitting radial movement freedom, as the oil film can accommodate radial displacements without creating hyperstatic constraints that would arise from rigid mechanical contact
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 effectively maintains the axial position of the sun gear, absorbs axial forces, and allows radial freedom, preventing hyperstatic effects while minimizing the axial dimensions of the reduction gear, thus enhancing operational efficiency and reducing stress concentrations.
Implementation Method 1
said lubrication circuit comprising at least one channel configured to convey oil onto said bearing surface and to form a film of oil between this bearing surface and the sun gear
Data Source
AI summary
A mechanical reduction gear of a turbine engine, in particular for an aircraft, includes a sun gear having external toothing, a ring gear which extends around the sun gear and has internal toothing, planet gears which are in mesh with the sun gear and the ring gear and which have toothings of different diameters, a planet carrier which supports bearings for guiding the planet gears in rotation, and a lubrication circuit of the reduction gear. The planet carrier has a hydrodynamic abutment on which the sun gear is configured to bear axially.