Roller Screw Force Actuator for Underwater Load Distribution
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Solution Overview
Problem
Existing force actuators for underwater applications, such as blowout preventers and well-completion equipment, face challenges in distributing load accurately and maintaining high force requirements while preventing bending moments and ensuring reliability, especially in underwater environments.
Innovation Solution
A compact force actuator design featuring a displaceable roller screw driven by an electric motor with a rotatable roller cage and threaded rollers, incorporating separate pressure-compensation chambers and an electromagnetic brake, allowing for remote control and external activation, with independent coil sets for redundancy and fluid viscosity optimization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If parallel screw-nut connections are used to distribute load, then force capacity is improved, but manufacturing precision and assembly accuracy requirements increase significantly
Solution Approach 1:
The actuator divides the load distribution function into separate components: the roller cage independently guides and supports multiple threaded rollers, while each roller independently engages with the roller screw. This segmentation allows each component to be manufactured and assembled separately with standard tolerances, eliminating the need for high-precision synchronized assembly of multiple screw-nut connections.
Solution Approach 2:
The roller cage acts as an intermediary component that mediates between the motor and the threaded rollers. It provides a common rotational interface that automatically ensures synchronized movement of all rollers without requiring precise adjustment of each roller's position, thus simplifying assembly while maintaining load distribution.
2Measurement precision
If the roller screw is prevented from rotating, then linear displacement accuracy is improved, but friction and wear increase
Solution Approach 1:
Instead of preventing the roller screw from rotating through direct mechanical constraint, the design inverts the approach: the roller screw is allowed to rotate freely, and linear displacement is achieved by preventing the rollers from rotating on their axes. This is accomplished through the roller cage geometry and roller support bearings, which constrain roller rotation while allowing screw rotation, thereby reducing friction and wear on the screw-roller interface.
3Device complexity
If a single motor drives the roller cage, then device complexity is reduced, but reliability decreases
Solution Approach 1:
The design incorporates preliminary redundancy measures by providing multiple threaded rollers that can independently engage with the roller screw. If one motor fails or one roller becomes damaged, the other rollers can continue to provide driving force, allowing the actuator to maintain partial functionality. This preliminary redundancy approach enhances reliability without requiring multiple motors or complex control systems.
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 enables the generation of high forces with compact dimensions, improved load distribution, and enhanced reliability, including underwater operation and remote control capabilities, ensuring consistent performance even in case of motor failure.
Implementation Method 1
The force actuator is provided with an electromagnetic brake, wherein a first part of the brake is anchored to a motor housing and a second rotatable part is attached in an axially displaceable manner to the sun gear of a first planetary gearing.
Implementation Method 2
a roller cage which is in engagement with the transmission elements is provided with at least one threaded roller, which is in threaded engagement with the roller screw
Data Source
AI summary
A force actuator including an actuator housing, in which, via transmission elements, an electric motor is arranged to drive a displaceable roller screw along the longitudinal axis of the force actuator, and in which a rotatable roller cage which is in engagement with the transmission elements is provided with at least one threaded roller, the threaded roller being in threaded engagement with the roller screw, and the roller screw being prevented from rotating around the longitudinal axis.