Aircraft Actuator Clearance Take-Up Mechanism
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Solution Overview
Problem
Existing horizontal stabilizer actuators for aircraft suffer from stress on common parts during both primary and secondary path operations, leading to unavailability if a common part breaks, and lack detection mechanisms for secondary path engagement, which can result in catastrophic loss of mechanical connection.
Innovation Solution
A control actuator design with a primary path and a secondary path featuring a clearance take-up device with a tightening ramp, which reduces stress on secondary parts by eliminating clearance between the secondary part and housing, ensuring engagement and contact upon primary path failure, and includes position sensors for detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the secondary path comprises common parts connecting the actuator to the fuselage and horizontal stabilizer, then the secondary path can take over the primary path in case of breaking, but the common parts are stressed both during primary and secondary path operation, leading to unavailability if a common part breaks
Solution Approach 1:
The invention divides the control system into two independent mechanical paths: a primary path (screw and primary nut) and a secondary path (secondary part and housing). By segmenting the common parts into path-specific components, the secondary path no longer shares structural elements with the primary path, eliminating the stress accumulation problem on common parts while maintaining redundancy capability.
Solution Approach 2:
The clearance take-up device acts as an intermediary mechanism between the secondary part and housing. It includes a clearance take-up part with an inclined ramp that, when activated by displacement in the first direction, engages to prevent displacement in the second direction and tightens the secondary part against the housing. This intermediary device enables the secondary path to become load-bearing only when needed, without subjecting it to continuous stress during primary path operation.
2Strength
If the clearance between the secondary part and housing is maintained, then the secondary path remains unstressed during normal operation, but the horizontal stabilizer may float due to clearance from machining tolerances and deformations
Solution Approach 1:
The clearance take-up device is pre-configured with an inclined ramp that automatically activates when the primary path fails and the secondary part displaces in the first direction. This preliminary arrangement ensures that the clearance is taken up and the secondary path is tightened against the housing at the precise moment it becomes operational, preventing floating while maintaining stress-free conditions during normal primary path operation.
Solution Approach 2:
The system dynamically changes the physical state of the secondary path by transitioning from a cleared, unstressed state during primary path operation to a tightened, contact state when the secondary path becomes operational. The inclined ramp mechanism converts displacement in the first direction into tightening force, changing the contact parameter between the secondary part and housing from zero to positive contact pressure.
3Loss of information
If position sensors are added to detect secondary path engagement, then the pilot is informed of breakdown, but the device complexity increases
Solution Approach 1:
Position sensors are integrated into the actuator system to provide feedback on the displacement of the secondary part and the engagement state of the clearance take-up device. When the secondary part displaces in the first direction and the clearance take-up part engages to prevent displacement in the second direction, the sensors detect this state change and provide information to the pilot, enabling awareness of secondary path activation without requiring complex additional systems.
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 limits stress on secondary path components, ensures continuous operation by engaging the secondary path upon primary path failure, and prevents floating of the horizontal stabilizer through complete clearance take-up, including machining tolerances and deformations, while providing pilot feedback on secondary path engagement.
Implementation Method 1
a clearance take-up device, the clearance take-up device comprising a clearance take-up part having a tightening ramp inclined relative to the axis, the clearance take-up device being arranged, in case of breaking of the primary path causing displacement of the secondary part relative to the housing along the axis in a first direction tending to reduce the clearance between the secondary part and the housing, to move the clearance take-up part towards a blocking position in which the clearance take-up part prevents displacement of the secondary part relative to the housing in a second direction, opposite the first direction
Implementation Method 2
the elastic return element comprises a torsion spring
Data Source
AI summary
The invention relates to an actuator (4) for controlling a horizontal stabilizer (3) of an aircraft, including: a primary channel including a screw (6) and a primary nut (7), the primary nut (7) being suitable for engaging with the screw (6), such that a rotation of the screw (6) relative to the primary nut (7) about a rotation axis (X) causes the primary nut (7) to translate relative to the screw (6) along the axis (X), such as to move the horizontal stabilizer (3); a secondary channel including a secondary part (25, 28), and a housing (23, 26), the secondary part (25, 28) being mounted in the housing (23, 26) with play between the secondary part and the housing, in which the secondary channel also includes a play take-up device (27), configured to, in the event of a breakdown of the primary channel causing the secondary part (25, 28) to move relative to the housing, eliminate the play between the secondary part (25, 28) and the housing (23, 26) such as to keep the secondary part (25, 28) in contact with the housing (23, 26).