Turbojet Transmission Oil Distribution for Pressure Balance
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Solution Overview
Problem
Conventional transmission assemblies in turbojets with epicyclic gear trains suffer from unbalanced pressure fields in oil bearings, leading to degraded drive force transmission and increased risk of bearing damage due to centrifugal forces, which are not adequately compensated by existing configurations.
Innovation Solution
A transmission assembly with an oil distribution system that injects oil at different pressures into the inner and outer portions of the gap between the rotary pivot and pivot portion, creating a pressure differential to counteract centrifugal forces, thereby improving the symmetry of the pressure field and reducing wear and energy transfer inefficiencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional single-pressure oil injection is used in the bearing gap, then the structure is simple, but the centrifugal pressure gradient cannot be compensated leading to unbalanced pressure field
Solution Approach 1:
The oil distribution system is segmented into multiple independent injection circuits, each equipped with its own pressure control means. The gap between the rotary pivot and pivot portion is divided into different zones (inner portion and outer portion) that receive oil at different pressures, allowing independent control of pressure in each zone to compensate for the centrifugal pressure gradient.
Solution Approach 2:
Different zones of the bearing gap are provided with different oil injection pressures according to their specific requirements. The outer portion of the gap, which experiences higher centrifugal forces, receives oil at a higher pressure than the inner portion, creating a locally optimized pressure distribution that compensates for the centrifugal effect.
2Reliability
If higher oil injection pressure is applied to compensate centrifugal forces, then pressure field symmetry improves, but energy consumption increases
Solution Approach 1:
Instead of applying high pressure uniformly throughout the entire bearing gap, the system applies different pressures to different zones. Only the outer portion of the gap, where centrifugal forces are most significant, receives higher pressure oil injection, while the inner portion receives lower pressure, thereby minimizing overall energy consumption while achieving the necessary pressure compensation.
Solution Approach 2:
The system dynamically adjusts the injection pressure parameter based on the rotational speed and load conditions. The pressure control means modify the oil injection pressure in real-time to match the actual centrifugal forces experienced, avoiding excessive energy consumption when high pressure is not needed while ensuring adequate compensation when required.
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 effectively compensates for centrifugal pressure gradients, reducing the risk of contact between pivot components, enhancing energy transfer efficiency, and improving the overall performance of the transmission member by maintaining a stable and symmetrical pressure distribution.
Implementation Method 1
the oil film in the gap is subjected to a centrifugal force Fc that is proportional to the square of the speed of rotation about the axis of rotation R and that is directed radially in the rotating reference frame
Implementation Method 2
centrifugal volume forces then generate a radial centrifugal gradient Gc in the oil film, which gradient increases outwards
Implementation Method 3
injection orifices putting the oil reception chamber into fluid flow communication with the gap between the rotary pivot and the pivot portion so as to form a fluid bearing
Data Source
AI summary
A transmission assembly including a transmission member and an oil distribution system. The transmission member includes a rotary pivot, and a pivot portion for pivoting about the rotary pivot; the oil distribution system is to receive oil feed and to transfer it to an oil reception chamber of the rotary pivot; the rotary pivot includes injection orifices putting the oil reception chamber into fluid flow communication with the gap between the rotary pivot and the pivot portion to form a fluid bearing; and the transmission assembly is for injecting oil into the gap at a first pressure into an outer portion of the gap, and at a second pressure into an inner portion of the gap, the second injection pressure being different from the first injection pressure.