Electric Actuator Bidirectional Compliance Load Path
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Solution Overview
Problem
Electric retract actuators in aircraft landing gear experience increased wear and reduced lifespan due to the incorporation of roller screws in the load path, which increases resistance to landing and ground loads, leading to maintenance challenges and reduced stiffness.
Innovation Solution
An adjustable electric actuator system that utilizes a high backdriving load to remove the roller screw or ball screw from the landing gear load path, incorporating a compliance element and limitation-retraction elements to manage deflections and loads, allowing for efficient motor sizing and reduced wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a roller screw is incorporated into the landing gear load path to provide stiffness and deflection resistance, then the actuator can react landing or ground loads, but the actuator experiences increased wear, requires additional maintenance, and its lifespan is reduced
Solution Approach 1:
The roller screw is extracted from the landing gear load path and replaced with a compliant element that has high backdriving load capability. This allows the actuator to provide stiffness without forcing the roller screw into the load path, thereby reducing wear and extending actuator lifespan while maintaining the necessary structural rigidity.
Solution Approach 2:
The invention changes the backdriving load parameter of the actuator by using a compliant element with high backdriving load capability instead of a roller screw. This parameter change enables the actuator to provide sufficient stiffness and deflection resistance without the excessive wear associated with roller screws in the load path.
2Weight of stationary object
If the backdriving load is increased to reduce motor sizing in an electric retract actuator, then the motor size can be reduced, but the actuator is forced to react substantial landing or ground loads which increases wear and maintenance requirements
Solution Approach 1:
The invention converts the high backdriving load, which would normally force the actuator to react substantial landing or ground loads and cause wear, into a beneficial compliant element property. The compliant element with high backdriving load capability provides the necessary stiffness to support motor sizing reduction while its compliance prevents the actuator from reacting harmful landing or ground loads, thereby reducing wear and maintenance requirements.
3Power
If an unpowered electric retract actuator relies on roller screw backdriving capability for stiffness, then motor sizing can be optimized, but the roller screw is incorporated into a load path that forces the actuator to react substantial landing or ground loads
Solution Approach 1:
The roller screw is extracted from the landing gear load path and replaced with a compliant element. This extraction allows the actuator to maintain optimized motor sizing through high backdriving load capability without being forced to react substantial landing or ground loads through the roller screw, thereby resolving the contradiction between power efficiency and force reaction.
Solution Approach 2:
The invention changes the mechanical property parameters of the actuator by using a compliant element with high backdriving load capability instead of a roller screw. This parameter change enables the actuator to achieve optimized motor sizing while preventing the incorporation of the drive mechanism into a load path that would force reaction of substantial landing or ground loads.
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 system provides weight savings, efficient component sizing, and minimizes deflections caused by landing or ground loads, reducing wear and maintenance needs while maintaining actuator performance.
Implementation Method 1
the actuator length changes in response to attachment deflections while not reacting with appreciable loads
Implementation Method 2
utilizes a high backdriving load to remove the roller screw or ball screw from the landing gear load path
Data Source
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AI summary
An adjustable electric actuator system includes an actuator output (35), a compliance element (36) coupled to the actuator output, and an end fitting element (31) encapsulating at least a portion of the compliance element, wherein the compliance element is guided a first distance in a first axial direction by the actuator output, the first distance being limited by a first limitation element.