Aircraft Turbine Gear Reducer Helical Splines for Crown Stability
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Solution Overview
Problem
Mechanical reducers for turbomachines, particularly those with double-floor satellites, face challenges in efficiently transmitting radial and axial efforts to the crown, which can lead to crown instability and potential disengagement.
Innovation Solution
The mechanical reducer design incorporates a crown with helicoid external grooves that engage with internal grooves of the holder, allowing axial movement and orientation of the grooves to direct the crown towards an axial stop, ensuring axial immobilization and efficient effort transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If double-stage meshing satellites are used in the mechanical reducer, then the speed and torque transformation capability is improved, but the risk of misalignment and instability of the crown gear increases
Solution Approach 1:
Helical splines are introduced as an intermediary mechanism between the crown gear and crown carrier. These splines mediate the force transmission by converting radial and axial loads into controlled axial movement of the crown gear against the stop, preventing direct misalignment forces from affecting the gear meshing.
Solution Approach 2:
The orientation of the helical splines is specifically designed to change the direction of force transmission. By orienting the splines at appropriate angles, radial and axial forces on the crown gear are transformed into axial movement along the spline direction, stabilizing the crown gear position while maintaining double-stage meshing functionality.
2Power
If the crown gear is subjected to significant radial and axial forces, then the power transmission capability is improved, but crown gear displacement and misalignment occur
Solution Approach 1:
Helical splines serve as an intermediary that handles the transmission of radial and axial forces. Instead of these forces acting directly on the crown gear teeth and causing displacement, the splines convert them into axial movement of the entire crown gear assembly against the stop, maintaining positional stability.
Solution Approach 2:
The helical shape of the splines introduces a curved geometry that naturally guides the force transmission path. The helical orientation allows forces to be distributed along the spiral path, converting problematic radial and axial components into controlled axial movement, thereby preventing crown gear displacement.
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 effectively immobilizes the crown axially, ensuring stable transmission of torques and axial efforts, thereby preventing crown instability and disengagement during operation.
Implementation Method 1
the crown comprising helical external splines which are engaged in complementary internal splines of the crown carrier and which are configured to cooperate by sliding with these internal splines so as to force the crown to be held against the stop in operation
Data Source
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AI summary
Mechanical reducer (6) of turbomachine (1), in particular of aircraft, this reducer comprising: - a sun gear (7), - a ring gear (9) surrounded by a ring carrier (34), and - planet gears (8) meshed with the sun gear (7) and the ring gear (9), the ring carrier (34) comprising an axial stop (40) on which the ring gear (9) is configured to bear, and the ring gear comprising external helical splines (44) which are engaged in internal splines (42) complementary to the ring carrier (34) and which are configured to cooperate by sliding with these internal splines so as to force the holding of the ring gear against the stop (40) in operation.