Planetary Gear Cone Surfaces for Turbomachine Retaining Force
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Solution Overview
Problem
In planetary gear devices for turbomachines, the retaining forces from press fits between bolts and planetary carrier areas are overcome at high loads, leading to undesired relative movements and wear, which shortens the service life and increases weight due to the need for high rigidity to prevent detachment.
Innovation Solution
The planetary gear device incorporates cone surfaces on the planetary carrier areas that interact with a tensioning appliance to create pre-stressing forces counteracting centrifugal forces, allowing for reduced structural component weight and easier mounting by using a coupling element and tensioning appliance to apply axial tensioning forces, thereby maintaining contact pressure in press fits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the rigidity of the planetary carrier areas is increased to prevent detachment of press fits during operation, then the reliability is improved, but the weight of the planetary gear increases
Solution Approach 1:
The patent applies preliminary action by creating pre-stress in the bolts through wedge elements before operational loads are applied. The wedges are positioned in the connection areas between bolts and planetary carrier areas to generate initial retaining forces that counteract centrifugal forces during operation, preventing detachment without requiring increased structural rigidity or weight
Solution Approach 2:
The patent changes the physical state and distribution of forces by introducing wedge elements that convert axial pre-stress into radial retaining forces. This parameter change allows the press fit connection to maintain adequate retaining forces under operational loads without increasing the rigidity or weight of the planetary carrier areas
2Ease of manufacture
If conventional mounting methods without pre-stress are used, then the ease of manufacture is improved, but relative rotational movements occur leading to wear and shortened service life
Solution Approach 1:
The wedge elements are positioned during the mounting process to create pre-stress in the bolts before the planetary gear enters service. This preliminary action ensures that retaining forces are already present to prevent relative rotational movements between bolts and planetary carrier areas, eliminating wear issues while maintaining a relatively simple manufacturing process
Solution Approach 2:
The wedge elements serve as intermediary components between the bolts and planetary carrier areas. These wedges transmit and amplify the pre-stress forces, creating adequate retaining forces without requiring complex mounting procedures or specialized equipment beyond standard press fit capabilities
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 design prevents relative rotational movements between the support appliance and planetary carrier areas under high loads, achieving a longer service life and lower structural component weight while allowing for smaller press fit overdimensions and reduced mounting risks.
Implementation Method 1
a force that respectively results from the axial tensioning force of the tensioning appliance applied on the cone surfaces of the planetary carrier areas via the coupling element of the tensioning appliance and presses the connection areas inward in the radial direction is applied at the connection areas between the support appliances and the planetary carrier areas
Implementation Method 2
During operation of the jet engine, strong centrifugal forces act at the planetary wheels of the planetary gear due to the high rotational speeds of the planetary carrier
Implementation Method 3
The cone surfaces of the planetary carrier areas and the cone surfaces of the tensioning appliance act together in such a manner that a force that respectively results from the axial tensioning force... presses the connection areas inward in the radial direction
Implementation Method 4
the retaining forces that respectively result from the compressive force... counteract the centrifugal force
Data Source
AI summary
A planetary gear device for a turbomachine includes a planetary carrier and planetary wheel arranged in an axial direction between two planetary carrier areas connected to a support appliance, with the planetary wheel rotatably mounted on the support appliance. On outer sides facing away from the planetary wheel, the planetary carrier areas include cone surfaces that enclose connection areas with the support appliance, with diameters decreasing with increasing axial distance from the planetary wheel. Cone surfaces of a tensioning appliance radially enclose and are respectively adjusted thereto and act together such that a force that respectively results from an axial tensioning force of the tensioning appliance applied on the cone surfaces of the planetary carrier areas is applied at the connection areas between the support appliance and the planetary carrier areas. The tensioning appliance cone surfaces operatively connect via a coupling element.