Valve Actuator Torque Limiting Coupling for Overload Protection

Solution Overview

Problem

Actuated valve assemblies face issues with excessive torque transfer, which can lead to damage of the valve element, valve shaft, and actuator, especially when the valve element becomes stuck or is subjected to high fluid pressure.

Innovation Solution

A torque limiting coupling assembly is introduced, which is disposed between the valve shaft and the actuator. This assembly includes a valve shaft coupling with helical grooves and an actuator coupling with linear axial grooves, along with a sleeve and a bias element. The bias element compresses when excessive torque is applied, decoupling the rotation of the valve shaft from the actuator and translating the torque into a linear force.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the actuator is directly coupled to the valve shaft, then the torque transfer is efficient and reliable, but the valve components are vulnerable to excessive torque damage when the valve element becomes stuck or is subjected to high fluid pressure

Engineering Contradiction:

Improveprotection against excessive torqueVSAvoidcoupling assembly structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The torque limiting coupling assembly acts as an intermediary component between the actuator and valve shaft. It includes a driving gear, driven gear, and bias element that collectively mediate the torque transmission, allowing normal torque to pass through while limiting excessive torque that could damage valve components

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The bias element (spring) is pre-loaded to provide beforehand cushioning against excessive torque. When the valve element becomes stuck or is subjected to high fluid pressure, the spring compresses to absorb the excess torque before it can reach the valve shaft, preventing damage in advance

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Reliability

If a torque limiting coupling assembly is introduced between the valve shaft and actuator, then the valve components are protected from excessive torque, but the device complexity increases

Engineering Contradiction:

Improveprotection against excessive torqueVSAvoidcoupling assembly structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The torque limiting coupling assembly acts as an intermediary component between the actuator and valve shaft. It includes a driving gear, driven gear, and bias element that collectively mediate the torque transmission, allowing normal torque to pass through while limiting excessive torque that could damage valve components

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The bias element (spring) is pre-loaded to provide beforehand cushioning against excessive torque. When the valve element becomes stuck or is subjected to high fluid pressure, the spring compresses to absorb the excess torque before it can reach the valve shaft, preventing damage in advance

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Reliability

If the bias element compresses to decouple the rotation, then the torque is limited and valve components are protected, but the energy transfer efficiency decreases

Engineering Contradiction:

Improveprotection against excessive torqueVSAvoidtorque translation to linear force

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The system dynamically changes the torque parameter by allowing the bias element to compress when excessive torque is detected. This parameter change transforms the torque relationship from direct coupling to spring-loaded decoupling, protecting components while accepting temporary energy loss during abnormal conditions

Inventive Principle:

Principle #35Parameter changes

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 torque limiting coupling assembly effectively shields the valve assembly from excessive torque, preventing damage to the valve components while maintaining the ability to move the valve element between positions, even under conditions of high resistance or pressure.

Implementation Method 1

Torque applied to the torque limiting coupling assembly by the actuator is translated into a linear force which tends to compress a bias element of the torque limiting coupling assembly

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Data Source

PatentUS12209681B1Torque limiter for valve actuators

Publication Date: 2025.01.28 WATTS REGULATOR CO

AI summary

A torque limiting coupling assembly shields a valve actuator from abnormally high levels of torque. In normal operation, an actuator coupling transfers a driving torque from an actuator coupling to a valve shaft coupling and the valve shaft coupling engenders a shaft torque on a shaft of a valve. In torque actuated operation, when a counter torque applied to the shaft coupling exceeds a threshold value, the actuator coupling freely rotates relative to the valve shaft coupling and the driving torque is transferred to a biasing element of the torque limiting coupling assembly rather than to the valve shaft coupling, thereby shielding the valve or the actuator from high levels of torque.