Compact Linear-to-Rotary Actuator With External Torque Linkage
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Solution Overview
Problem
Existing rotary actuators face challenges such as sealing issues, side loads on seals, and limited rotational range, while linear actuators are bulky and inefficient in providing rotary motion, making it difficult to achieve compact, leak-free, and efficient rotary motion transmission in mechanical devices like aircraft flight control surfaces.
Innovation Solution
A compact linear-to-rotary motion apparatus that includes a linear actuator with a piston shaft and a rotor arm, where the piston shaft's linear motion is converted to rotary motion through a torque linkage, reducing side loads on seals and fitting within a smaller design envelope than traditional rotary actuators, using a guide structure to guide movement and reduce bending moments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional rotary actuators are used to deliver rotary motion, then constant torque and compact space are achieved, but seals with side loads cause leakage and reliability issues
Solution Approach 1:
The patent extracts the sealing function from the rotary actuator by eliminating rotary seals entirely. The linear actuator uses only linear seals that move axially without side loads, and the rotary motion is generated externally through linkage mechanisms (torque links and bellcranks) outside the sealed chamber, thus removing the source of leakage problems
Solution Approach 2:
The patent replaces the traditional rotary mechanical sealing system with a linear actuation system combined with external mechanical linkages. The linear actuator generates linear motion that is converted to rotary motion through torque links and bellcranks, substituting the need for rotary seals with seal-free linear motion and external rotary mechanisms
2Reliability
If linear actuators are used to provide rotary motion, then simplicity and leak-free performance are achieved, but they occupy significantly more space than rotary actuators
Solution Approach 1:
The patent merges the linear actuator with external linkage mechanisms (torque links and bellcranks) to create an integrated system that combines the space advantages of linear actuators with the rotary motion output of traditional rotary actuators. The linear actuator and its linkages are positioned to utilize available space efficiently, achieving compact overall dimensions
Solution Approach 2:
The patent arranges the linkage mechanisms in three-dimensional space to convert linear motion to rotary motion without increasing the primary dimensional envelope. The torque links and bellcranks are positioned to rotate about external axes, utilizing vertical and lateral dimensions rather than increasing the linear actuator's stroke length
3Reliability
If linear actuators are used to provide rotary motion, then leak-free performance is achieved, but the operating range of rotary motion is limited
Solution Approach 1:
The patent employs dynamic linkage mechanisms (torque links and bellcranks) that can adapt their geometry and configuration to achieve different rotary motion ranges. The linkages are designed with adjustable pivot points and link lengths that can be optimized for specific rotation ranges, allowing the same linear actuator to provide variable rotary output depending on the application requirements
4Volume of moving object
If compact linear-to-rotary motion apparatus is designed, then space efficiency is improved, but guide structures are needed to reduce bending moments on the piston
Solution Approach 1:
The patent introduces guide structures as intermediary elements between the linear actuator and the external linkage system. These guides serve as mediators that constrain the piston motion to a precise linear path, preventing lateral displacements and bending moments while maintaining the compact configuration. The guides are integrated into the actuator housing or mounting structure
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 apparatus achieves efficient rotary motion transmission with reduced side loads on seals, fitting within a compact space, and providing a similar or improved range of motion compared to traditional rotary actuators, while minimizing backlash and maintaining a flat torque curve.
Implementation Method 1
A linear-to-rotary apparatus includes a linear actuator that drives a piston shaft, where movement of the piston shaft converts linear motion to a rotary output of a rotor arm via one or more links
Implementation Method 2
A compact linear-to-rotary motion apparatus that includes a linear actuator with a piston shaft and a rotor arm, where the piston shaft's linear motion is converted to rotary motion through a torque linkage, reducing side loads on seals and fitting within a smaller design envelope than traditional rotary actuators, using a guide structure to guide movement and reduce bending moments
Data Source
AI summary
The subject matter of this specification can be embodied in, among other things, a linear-to-rotary apparatus that includes a linear actuator having an actuator housing including a piston chamber, a piston shaft disposed in the piston chamber, and a rotor apparatus. The rotor apparatus includes a rotary joint defining a rotational axis, a rotor arm extending radially from the rotary joint and configured to at least partially pivot about the rotary joint, and a torque linkage pivotably connected to the rotor arm. The torque linkage is also attached to an end of the piston shaft of the piston at a pivot connection joint, where the pivot connection joint defines a pivot axis that is substantially perpendicular to the translation axis of the piston shaft.