Subsea Electric Actuator Fail-Safe Spring Design
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Solution Overview
Problem
Existing subsea valve control systems, particularly hydraulic and electric actuators, face challenges such as leakage, increased costs, and reduced reliability due to distance and depth limitations, with hydraulic actuators suffering from pressure loss and long response times, and electric actuators being vulnerable to power loss.
Innovation Solution
A subsea electric actuator design featuring a housing filled with dielectric oil, an electric motor, brake, clutch, and spring, with additional components like planetary gear, ball screw, damper, CPU, and sensors to ensure fail-resistive operation, reduce leakage, and enhance diagnostic capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If hydraulic actuators are used for subsea valve control, then the valves can be operated remotely, but the response time becomes too long and pressure is lost over distance
Solution Approach 1:
The invention extracts the power source from the remote control system by installing an electric motor directly on the subsea actuator, eliminating the need for long hydraulic lines and umbilicals. This allows the actuator to operate independently at the wellhead, dramatically reducing response time while eliminating pressure loss over distance.
Solution Approach 2:
The invention introduces an intermediary power conversion system consisting of an electric motor and drive electronics that converts electrical signals from the control center into mechanical motion locally at the actuator. This intermediary system eliminates the need for direct hydraulic power transmission over long distances.
2Reliability
If existing electric actuators are used, then response time is improved, but reliability decreases due to vulnerability to power loss
Solution Approach 1:
The invention incorporates a spring-loaded fail-safe mechanism that is pre-charged and ready to actuate the valve to a safe position in the event of power loss. This beforehand cushioning ensures that the valve can be reliably closed even when electrical power is unavailable, eliminating the vulnerability to power loss.
Solution Approach 2:
The invention converts the potential harm of power loss into a benefit by using the failure condition to trigger the spring-loaded fail-safe mechanism. When power is lost, the spring automatically actuates the valve to a safe position, turning a harmful event into a protective action.
3Adaptability or versatility
If hydraulic actuators are used in deeper waters, then valve control is achieved, but cost and size of hydraulic lines and umbilicals increase
Solution Approach 1:
The invention extracts the hydraulic power transmission infrastructure (lines, umbilicals, accumulators) from the system by replacing it with an electric motor-driven actuator. This eliminates the complex hydraulic infrastructure that becomes increasingly costly and difficult to manage in deeper waters.
Solution Approach 2:
The invention replaces the hydraulic mechanical power transmission system with an electrical power system. The electric motor converts electrical energy directly into mechanical motion, eliminating the need for hydraulic fluid, pressure vessels, and complex fluid power transmission 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 provides reliable and efficient valve control with reduced leakage, lower operational costs, improved safety, and increased reliability, enabling operation in deeper waters without hydraulic power units or umbilicals, and enhanced diagnostic capabilities.
Implementation Method 1
a housing configured to be filled with dielectric oil
Implementation Method 2
the clutch and the brake are configured to maintain the spring in a compressed position
Implementation Method 3
the planetary gear and the multi-turn gear assembly are configured to multiply the torque provided by the electric motor
Implementation Method 4
the ball screw and the nut screw are configured to convert the torque provided by the motor into linear thrust to compress the spring
Implementation Method 5
the damper can be configured to displace the dielectric oil to a flow regulating orifice
Data Source
AI summary
A subsea electric actuator includes a housing configured to be filled with dielectric oil, an electric motor, a brake, a clutch, and a spring. The clutch and the brake are configured to maintain the spring in a compressed position. In certain embodiments, the actuator further includes a planetary gear and a multi-turn gear assembly, such that the planetary gear and the multi-turn gear assembly are configured to multiply the torque provided by the electric motor. The actuator can further include a ball screw and a nut screw configured to convert the torque provided by the motor into linear thrust to compress the spring.