Actuator Failsafe Spring Mechanism
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Solution Overview
Problem
Electric actuators face difficulties in closing a valve when the electrical supply fails, especially in inaccessible locations such as submerged positions, where auxiliary equipment is ineffective.
Innovation Solution
An actuator with a rotatable shaft and a mechanical energy storage element, typically a spring, allows the actuator shaft to move between angular positions, enabling the valve to close in case of energy failure, utilizing a gearbox and releasable connectors to manage energy storage and transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If auxiliary equipment is added to manually rotate the actuator shaft, then the valve can be closed manually, but the device complexity increases and the equipment becomes inaccessible in submerged positions
Solution Approach 1:
The patent merges the failsafe function directly into the actuator by integrating a spring mechanism and nut-screw thread system within the actuator housing. This eliminates the need for separate auxiliary equipment while maintaining the valve closing capability, thus resolving the contradiction between reliability and device complexity
Solution Approach 2:
The actuator is designed to be self-service capable by incorporating an energy storage element (spring) that automatically activates upon power failure. The spring holder and nut mechanism enable the actuator to autonomously rotate the shaft to close the valve without requiring external manual intervention or additional equipment, especially in inaccessible submerged locations
2Reliability
If a spring mechanism is integrated into the actuator, then the failsafe function is achieved, but the device complexity increases
Solution Approach 1:
The spring mechanism is nested within the actuator housing, with the spring holder positioned inside the housing and the nut integrated into the drive train components. This nested arrangement incorporates the failsafe mechanism within the existing actuator structure without requiring separate external components, thus achieving reliability while minimizing increases in device complexity
Solution Approach 2:
The nut serves multiple functions: it transmits rotational motion from the screw thread to rotate the actuator shaft during normal operation, and it also serves as the interface for the spring mechanism to displace and rotate the shaft during failsafe operation. This multi-functionality reduces the need for additional dedicated components, balancing reliability enhancement with device complexity
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 actuator provides a failsafe function, ensuring the valve can be safely closed during electrical supply failures, even in difficult-to-reach locations, by using mechanical energy storage to rotate the shaft to a safe position.
Implementation Method 1
an element for mechanically storing of energy, typically a spring
Implementation Method 2
element for mechanically storing of energy
Implementation Method 3
screw thread complementary fitting to the nut and connected to the actuator shaft
Data Source
Figure 1
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AI summary
An actuator device (1) comprising an actuator housing (2) with a fitting (4) for connecting the actuator (1) to an object (6), a motor (28) which via transmission elements (30, 32, 38, 40) drives an output actuator shaft (12) of the actuator (1), where the actuator shaft (12) is rotationally disconnectable from the motor (28), the actuator shaft (12) being rotatable between two angular positions where the one angular position may correspond to the object (6) being in a first condition and the other angular position may correspond to the object (6) being in a second condition, and where the actuator (1) is provided with an element (14) for storage of mechanical energy, the element (14) by energy cut-off to the actuator (1) being releasably arranged to be able to displace a nut (44) being prevented from rotating around its longitudinal axis, along a screw thread (42) complementary fitting to the nut (44), and connected to the actuator shaft (12), whereby the actuator shaft (12) is rotated between the two angular positions.