Actuator Axial Movement for Landing Gear Locking
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Solution Overview
Problem
The existing aircraft landing gear actuator system is vulnerable to failure of the secondary actuator, which can prevent the landing gear from locking in its fully deployed position, potentially impairing safe landing capabilities.
Innovation Solution
An actuator design featuring a drive shaft with limited axial movement and a spring biasing arrangement, combined with a releasable lock mechanism that allows axial movement beyond a release position, enabling the landing gear to be locked in its deployed position even if the secondary actuator jams, utilizing a motor-driven system and sensors for fault detection and control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the secondary actuator is provided to drive the strut against spring biasing to release the over-centre locking, then the landing gear can be stowed, but failure of the secondary actuator may prevent the strut from reaching its fully deployed locked position
Solution Approach 1:
The drive shaft is designed with dynamic characteristics that allow it to move axially beyond its normal operating range when subjected to excessive loads. The spring biasing arrangement provides a dynamic response that automatically permits axial movement when the actuator jams, enabling the landing gear to reach its locked position despite secondary actuator failure.
Solution Approach 2:
The system changes the axial position parameter of the drive shaft under different operating conditions. During normal operation, the drive shaft is constrained to prevent excessive axial movement. When the secondary actuator fails and jams, the increased load causes the drive shaft to move axially beyond its release position, changing the system state to permit landing gear locking.
2Stability of the object's composition
If the lock means is made robust to prevent axial movement of the actuator shaft, then normal operation is ensured, but axial movement is prevented even when the actuator jams
Solution Approach 1:
The lock means transitions from a static constraint to a dynamic system that responds to load conditions. The spring biasing arrangement creates a dynamic threshold: under normal loads, the lock means maintains its constraint function; under excessive loads indicating actuator failure, the system dynamically adjusts to permit axial movement.
Solution Approach 2:
The spring biasing arrangement acts as a pre-configured safety mechanism that cushions against the harmful effect of actuator jamming. By designing the system to anticipate potential failure, the spring allows the drive shaft to move axially when needed, preventing the landing gear from being trapped in an unsafe state.
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 reduces the risk of landing gear jamming by allowing axial movement of the actuator shaft, ensuring the landing gear can be safely locked in its deployed position, even in case of secondary actuator failure, and allows for controlled retraction to prevent further damage.
Implementation Method 1
a spring biasing arrangement biasing the drive shaft towards a predetermined axial position
Implementation Method 2
The actuator shaft may incorporate or be secured to a nut of the ball- or roller-screw type, the output member comprising a threaded shaft, rotation of the nut whilst the shaft is held against rotation causing axial movement of the shaft
Data Source
Figure 1~2
Figure 3
AI summary
An actuator comprises an actuator shaft (38) mounted for rotation by a drive shaft (30), releasable lock means (46) operable to restrict axial movement of the actuator shaft (38) relative to the drive shaft (30), and an output member (42) cooperating with the actuator shaft (38) such that rotation of the actuator shaft (38) drives the output member (42) for translating movement relative to the actuator shaft (38).