Spring-Return Shaft Coupling for Backlash-Free Rotary Control
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Solution Overview
Problem
Conventional coupling devices for rotary actuators and mechanical devices with spring return modules suffer from inherent backlash, which reduces the accuracy and reproducibility of rotational control, leading to potential unsafe or undesirable operational states in mechanical devices during power interruptions.
Innovation Solution
A coupling device with a spring return module that includes a first rotatable coupling engaging a portion of the mechanical device's shaft and an actuator coupling module with a second rotatable coupling engaging the rotary actuator, applying opposing torques to rotationally lock the shaft, thereby eliminating backlash and ensuring accurate angular position control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional spring return device is used with a rotary actuator, then automatic return to safe position is achieved, but backlash reduces accuracy and reproducibility of rotational control
Solution Approach 1:
The patent applies opposing torques in reverse directions: the spring return module applies torque in one direction while the actuator coupling module applies opposing torque in the opposite direction. This bidirectional torque application eliminates backlash by preventing play between mating surfaces, thereby improving manufacturing precision and rotational control accuracy while maintaining the reliability of automatic return to safe position.
2Manufacturing precision
If opposing torques are applied to rotationally lock the shaft, then backlash is eliminated and angular position control accuracy is improved, but device complexity increases
Solution Approach 1:
The patent merges the spring return device with the actuator coupling into a single integrated coupling device. The spring return module and actuator coupling module share common components such as the rotatable shaft and housing, allowing both functions (fail-safe return and backlash elimination) to be achieved without proportionally increasing device complexity. This integration resolves the contradiction by combining multiple functions into a unified structure.
3Manufacturing precision
If the spring return module and actuator coupling module are integrated, then backlash is eliminated, but the complexity of assembly and maintenance increases
Solution Approach 1:
The integrated coupling device is segmented into distinct functional modules: the spring return module with its retainer and clock spring, and the actuator coupling module with its mounting provisions. These modules can be assembled and disassembled as separate units while maintaining the integrated backlash elimination function. This modular segmentation resolves the contradiction by enabling easier assembly and maintenance compared to a fully integrated non-modular design.
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 eliminates backlash, enabling precise and reproducible control of the mechanical device's rotational position, ensuring safe and desired operational states even during power interruptions, and allowing for fine adjustments in applications like valve operation.
Implementation Method 1
a spring engaged with the first rotatable coupling, wherein the first rotatable coupling is rotatable about a rotation axis, and wherein rotation of the rotatable coupling about the rotation axis in a first direction causes mechanical energy to be stored in the spring
Implementation Method 2
the clock-spring is wound up within the retaining band so that it stores mechanical energy and provides a torque on the rotatable shaft
Implementation Method 3
the spring return module is arranged to apply a torque that opposes a torque applied to the shaft by the rotary actuator
Implementation Method 4
the effect of the clock-spring is to provide a force on the rotatable shaft that acts to counteract rotation of the rotatable shaft in the first direction
Data Source
AI summary
The present invention provides a coupling device for coupling a rotary actuator to a mechanical device having a rotatable shaft. The coupling device comprises a spring return module with a first rotatable coupling configured to engage a first portion of the shaft, and a spring engaged with the first rotatable coupling, wherein the first rotatable coupling is rotatable about a rotation axis, and wherein rotation of the rotatable coupling about the rotation axis in a first direction causes mechanical energy to be stored in the spring. The coupling device further comprises an actuator coupling module comprising a second rotatable coupling. The second rotatable coupling is configured to engage a second portion of the shaft, the second rotatable coupling being further engageable with an output of the rotary actuator. The second rotatable coupling is rotatable about the rotation axis, the second rotatable coupling being rotatable relative to the first rotatable coupling about the rotation axis.