Linked Pitch Adjustment Mechanism for Contra-Rotating Propellers
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Solution Overview
Problem
Existing propulsion engine pitch adjustment mechanisms are complex and require multiple actuators to control the angular pitch of contra-rotating propellers, with no static structure for the rear propeller assembly, leading to a cumbersome arrangement with many bearings.
Innovation Solution
A propulsion engine design where the first and second pitch adjustment mechanisms are linked, allowing a single actuation means to vary the angular pitch of both sets of blades in a predetermined ratio, using a single actuator or multiple actuators generating a combined linear output, with unison rings ensuring all blades maintain the same angle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If two concentric hydraulic actuators are used to control the angular pitch of contra-rotating propellers, then the angular pitch of both propellers can be adjusted, but the mechanism becomes complex with many bearings and no static structure for the rear propeller assembly
Solution Approach 1:
The patent combines two separate pitch adjustment mechanisms into a single integrated mechanism. The first pitch adjustment mechanism is coupled to the second pitch adjustment mechanism such that a single actuator can control the angular pitch of both first and second propellers simultaneously, reducing the number of actuators from two to one and simplifying the overall structure
Solution Approach 2:
The single actuator serves multiple functions by controlling both the first and second pitch adjustment mechanisms through the coupled arrangement. This multi-functional design eliminates the need for separate actuators for each propeller, reducing complexity while maintaining full pitch control capability
2Ease of operation
If two independent actuation mechanisms are used for each propeller assembly, then each propeller can be controlled independently, but the arrangement becomes cumbersome with a large number of bearings
Solution Approach 1:
The patent merges the two independent actuation mechanisms into a single actuation system. The coupling between the first and second pitch adjustment mechanisms allows one actuator to control both propellers, reducing the bearing count from multiple bearings in two separate mechanisms to fewer bearings in the integrated mechanism
Data Source
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AI summary
A propulsion engine 20 for an aircraft comprises a first fan 30 having a set of first blades 32 and a second fan 40 having a set of second blades 42. There is provided a first angular pitch adjustment mechanism 50 coupled to the first set of blades 32, a second angular pitch adjustment mechanism 60 coupled to the second set of blades 42 and an actuation means 70 coupled to the first angular pitch adjustment mechanism 50. The first and second angular pitch adjustment mechanisms 50, 60 are coupled together such that when the actuation means generates an output, the angular pitch of each of the first blades 32 and each of the second blades 42 changes.