Dual Planetary Gear Actuator Jamming Redundancy
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Solution Overview
Problem
Electric actuators with planetary gear mechanisms are prone to jamming, which can cause delays and are not sufficiently reliable, especially in critical applications like aircraft systems, where mechanical separation mechanisms can introduce lag and are not always effective.
Innovation Solution
The design incorporates a dual planetary gear mechanism with a rotational member supported by a bearing and internal gears, allowing continuous rotation of the output section even when jamming occurs by utilizing two independent power transmission paths, one from each motor, and restricting the rotation of internal gears to maintain functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a planetary gear mechanism is used in an electric actuator, then the actuator can achieve compact design and high torque output, but jamming may occur in the gear when foreign substances enter, reducing reliability
Solution Approach 1:
The planetary gear mechanism is divided into multiple independent gear sets (first planetary gear mechanism and second planetary gear mechanism), each capable of independent operation. This segmentation allows the system to maintain functionality even when one gear set experiences jamming, thereby improving reliability without significantly increasing overall structural complexity
Solution Approach 2:
The patent incorporates a separation mechanism that can preemptively separate the planetary gear mechanism from the jack screw mechanism before jamming occurs. This preliminary action prevents foreign substances from causing complete system failure, maintaining reliability while keeping the gear structure intact
2Reliability
If a mechanical separation mechanism (clutch or shear pin) is used to release jamming, then the gear can be protected from damage, but the separation process causes time delay and is not sufficiently reliable
Solution Approach 1:
The patent replaces traditional mechanical separation mechanisms (clutch or shear pin) with a motor-driven separation system. The second motor can actively drive the planetary gear mechanism to reverse or disengage from jammed positions, eliminating the passive and delayed mechanical separation process. This substitution significantly reduces time delay and improves reliability by providing active control over the separation process
Solution Approach 2:
The system incorporates sensors and control mechanisms that enable the actuator to automatically detect jamming conditions and initiate separation procedures without external intervention. This self-service capability ensures rapid response to jamming events, minimizing time loss and maintaining high reliability
3Device complexity
If a jack screw mechanism is used for mechanical separation, then the actuator can achieve simple structure, but jamming in the jack screw requires mechanical separation that causes about 30 milliseconds delay
Solution Approach 1:
The patent replaces the jack screw mechanism with a planetary gear mechanism driven by motors. This substitution eliminates the need for mechanical separation procedures entirely, as the motors can actively control the gear mechanism to avoid and recover from jamming conditions. The result is a slight increase in structural complexity but a dramatic reduction in separation time delay
4Reliability
If the internal gear is allowed to rotate freely, then the planetary gear mechanism can operate smoothly, but rotation of the internal gear during jamming can cause further damage and reduce reliability
Solution Approach 1:
The patent incorporates a restraint mechanism for the internal gear that prevents it from rotating in directions that would exacerbate jamming conditions. By applying preliminary anti-action to potential harmful movements, the system protects the gear mechanism from further damage while maintaining operational capability through controlled rotation paths
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 configuration ensures high reliability and continuous operation of the output section with minimal time lag, even during jamming events, and reduces the risk of overall actuator failure by providing redundant power transmission paths, thus enhancing the actuator's performance and reducing the need for mechanical separation mechanisms.
Implementation Method 1
a rotational member supported by a bearing
Data Source
Figure 1
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Figure 3
AI summary
An electric actuator (1), comprising: an output section (30) receiving a reduced output from a first motor (11) through a rotational member (24B) supported by a bearing and through an internal gear (24A), wherein the output section (30) receives an output from a second motor (21) through a planetary gear mechanism that includes the internal gear (24A), a sun gear (22), and a planetary gear (23). Fig.1