Planetary Gear Self-Locking Mechanism Against Back-Driving
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Solution Overview
Problem
Existing gear sets lack a self-locking mechanism that prevents back-driving while allowing efficient forward driving, leading to inefficiencies and increased power requirements, especially in applications like butterfly valves where system forces can cause unwanted movement.
Innovation Solution
A self-locking apparatus for gear sets incorporating unidirectional engage/disengage components, such as locking wedges and ratchet mechanisms, that allow forward rotation in either direction while preventing back-driving by engaging/disengaging based on the position of planet pins in planet carrier slots.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a gear set is designed to allow forward driving in both directions, then the ease of operation is improved, but the ability to prevent back-driving is worsened
Solution Approach 1:
The locking mechanism is segmented into multiple independent locking elements (first locking element and second locking element) that can operate independently in different rotational directions. Each locking element has its own locking surface and engageable member configuration, allowing the gear set to be locked in one direction while remaining freely rotatable in the opposite direction.
Solution Approach 2:
The locking elements are configured with asymmetric geometries where the locking surfaces and engageable members are positioned to engage only in specific rotational directions. The first locking element prevents rotation in a first direction while allowing rotation in a second direction, creating directional asymmetry in the locking behavior.
2Reliability
If a worm and gear set with low helix angle is used to achieve self-locking, then the back-driving prevention is improved, but the energy efficiency is worsened
Solution Approach 1:
The invention extracts the locking function from the gear mesh itself and implements it through separate, dedicated locking elements that engage with the gear teeth. This allows the main gear set to operate with standard, efficient gear ratios while the locking function is provided by the extracted locking elements that engage only when needed to prevent back-driving.
Solution Approach 2:
The locking elements are designed to automatically engage and disengage based on the direction of rotation without requiring external control. When the gear set rotates in a direction that would cause back-driving, the locking elements automatically engage to prevent rotation. When rotated in the opposite direction, they automatically disengage, allowing free rotation.
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 prevents back-driving in both clockwise and counterclockwise directions, maintaining high efficiency (up to 99%) and reducing power consumption by allowing the gear set to be forward-driven efficiently without the need for continuous power input to counteract system forces.
Implementation Method 1
The frictional forces inherent in the gear set, system forces acting on the resting gears may at times cause unwanted movement thereof
Implementation Method 2
one or more unidirectional engage/disengage components, such as locking wedges and ratchet mechanisms
Data Source
Figure 1
Figure 2
Figure 2A
AI summary
A self-locking apparatus for a gear set permits forward-driving an input in clockwise or counterclockwise directions and substantially prevents an output from being driven in either or both of those directions. The device includes a gear set with planet gears arranged within a planet carrier within a fixed ring gear. Each of the planet gears is engaged with the planet carrier via a differentiating connector retained in an elongated slot in the planet carrier where it moves to the clockwise position when being forward driven in the clockwise direction and, when the planet carrier is back driven in the clockwise direction, the connector moves to the counter-clockwise position in the slot. This arrangement allows the gear set to be forward driven but not back driven. This differentiated action can engage/disengage with any form of unidirectional engage/disengage mechanism. The apparatus is useful in industrial applications requiring self-locking gear sets.