Rotary Actuator Stop Module With Resettable Non-Jamming Brake Linkage
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Solution Overview
Problem
Existing end-of-stroke stopping mechanisms for rotary drive actuators, such as geared rotary actuators in aircraft control systems, face challenges in quickly dissipating excess rotational kinetic energy while minimizing weight and size, and preventing jamming at travel limits, especially when reverse rotation is required for reset.
Innovation Solution
A stop module that mechanically links two gear stages with different rotational speeds, using a threaded first stage carrier and spur gear nuts to transmit rotational motion to a brake plate, which engages brake disks at travel limits to stop rotation, and reverses direction upon counter-clockwise input to reset.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a hard stop mechanism is used to quickly dissipate rotational kinetic energy at travel limits, then stopping speed is improved, but jamming occurs preventing reset by reverse rotation
Solution Approach 1:
The stop module employs dynamic binding where the brake plate is pushed against brake disks only during forward rotation to create a hard stop. During reverse rotation, the mechanism naturally releases the binding, allowing the brake plate to disengage and the system to reset without jamming. This dynamic behavior resolves the contradiction between achieving fast stopping and maintaining reset capability.
2Power
If a heavy-duty stopping mechanism is used to dissipate excess rotational kinetic energy, then energy dissipation capability is improved, but weight and size increase
Solution Approach 1:
The transmission assembly acts as an intermediary mechanism that translates the rotational motion of the second stage carrier into axial motion of the brake plate. This allows the stop module to leverage the existing gear stage dynamics rather than requiring a separate heavy-duty actuation system, achieving effective energy dissipation with minimal additional weight.
Solution Approach 2:
The stop module utilizes the inherent rotational speed differences between gear stages and the threaded portion of the first stage carrier to automatically actuate the brake plate. The system self-regulates based on rotation direction and speed, eliminating the need for external sensors, actuators, or control systems that would add weight and complexity.
3Reliability
If a complex stopping mechanism is used to prevent jamming and enable reset, then reliability is improved, but device complexity increases
Solution Approach 1:
The stop module is integrated with the existing multistage planetary gear system by utilizing the threaded portion of the first stage carrier and the rotational motion of the second stage carrier. This merging approach eliminates the need for separate actuation mechanisms, sensors, and control systems, achieving reliable anti-jamming functionality with minimal additional components.
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 jamming, ensures quick energy dissipation, and allows for resettable operation while minimizing weight and size, making it suitable for aircraft applications.
Implementation Method 1
The first stage carrier includes a threaded portion, and the second stage carrier includes gear teeth... a brake plate arranged for travel with the first and second nuts along an axis of the threaded portion
Implementation Method 2
the brake plate is caused to engage the first brake disk at a first end-of-stroke travel limit of the rotary actuator to stop rotation of the input shaft
Data Source
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AI summary
A rotary actuator has a stop module configured to mechanically link two gear stages travelling at different rotational speeds when an end-of-stroke travel limit is reached, thereby causing the rotary actuator to bind because relative motion between the gear stages is impeded.