Concentric Epicyclic Actuator With Fail-Safe Return Position
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Solution Overview
Problem
Existing electrical regulation equipment for fluid flow in aircraft systems lacks a reliable 'fail-safe' mechanism to return to a preferential position in the event of electrical power loss, and there is a need for equipment that is easy to assemble, has a limited footprint, and can operate in multiple modes.
Innovation Solution
The actuator features a concentric epicyclic reversible reducer with a torsion spring that drives the output shaft to a predetermined position when power is lost, utilizing a concentric epicyclic gearbox configuration to house the spring and reduce bulk, allowing for flexibility and torque over a 90° stroke, and includes an electronic control card for motor control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional electric motor with gearbox is used for valve control, then the device can regulate fluid flow, but it lacks automatic return-to-position capability upon power loss
Solution Approach 1:
The torsion spring is concentrically nested within the epicyclic gearbox structure, sharing the same central axis. The spring's outer end attaches to the housing while the inner end connects to the movable ring, allowing the spring to be housed within the existing gearbox footprint without adding external bulk. This nested configuration enables fail-safe return functionality while maintaining a compact overall device size.
Solution Approach 2:
The gear system is divided into two independent reduction stages: a first stage with a solar pinion and toothed wheel, and a second stage with planets having superimposed double external teeth. This segmentation allows the torsion spring to be applied specifically to the movable ring of the second stage, creating a modular fail-safe mechanism that can be integrated without redesigning the entire gearbox.
2Reliability
If a torsion spring is added to provide fail-safe return, then reliability improves, but the device footprint increases
Solution Approach 1:
The torsion spring is concentrically nested within the epicyclic gearbox structure, sharing the same central axis. The spring's outer end attaches to the housing while the inner end connects to the movable ring, allowing the spring to be housed within the existing gearbox footprint without adding external bulk. This nested configuration enables fail-safe return functionality while maintaining a compact overall device size.
Solution Approach 2:
The spring is arranged concentrically around the movable ring in a radial configuration rather than extending linearly from the output shaft. This dimensional arrangement allows the spring to provide rotational restoring torque while occupying minimal axial and radial space, fitting within the circular footprint of the epicyclic gearbox.
3Area of stationary object
If a complex epicyclic gearbox with double-teeth planets is used, then compactness is achieved, but manufacturing complexity increases
Solution Approach 1:
The gear system is divided into two independent reduction stages: a first stage with a solar pinion and toothed wheel, and a second stage with planets having superimposed double external teeth. This segmentation allows the torsion spring to be applied specifically to the movable ring of the second stage, creating a modular fail-safe mechanism that can be integrated without redesigning the entire gearbox.
Solution Approach 2:
The planets with superimposed double external teeth serve multiple functions: they engage with the solar pinion for power transmission, engage with the fixed ring for structural support, and engage with the movable ring for torque transmission and fail-safe return. This multi-functionality reduces the need for additional components, simplifying the overall assembly process despite the complex tooth configuration.
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 actuator ensures reliable 'fail-safe' operation by spontaneously returning to a predetermined position, facilitates easy assembly and reduced manufacturing costs, and allows for two distinct operating modes without modifying the epicyclic stage, enabling efficient fluid flow regulation in aircraft systems.
Implementation Method 1
a concentric torsion spring arranged around said movable ring, mechanically connected to the casing and to the movable ring, and configured to be able to spontaneously cause the movement of said movable ring and said output shaft to a predetermined position in the event of a loss of electrical power to said electric motor
Data Source
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AI summary
The invention relates to an actuator for electrical equipment for regulating a fluid flow in a conduit comprising a housing, an electric motor (10), a concentric epicyclic reversible reducer housed in said housing and mechanically connected to said motor and comprising a first reduction stage and a second reduction stage comprising at least one satellite (31) with superimposed external double teeth, said upper teeth being in contact with a fixed ring and said lower teeth being in contact with a movable ring (35), and a concentric torsion spring (42) arranged around said movable ring (35), mechanically connected to the housing and to the movable ring (35), and configured to be able to spontaneously drive the movement of said movable ring (35) and of an output shaft (40) into a predetermined position in the event of loss of electrical supply to said electric motor (10).