Depth-Compensated Accumulator Using Expandable Vessel
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Solution Overview
Problem
Existing subsea hydraulic power systems face challenges with long-distance operation, deep-sea deployment, and the need for a reliable energy storage solution that avoids spring-charged and piston-based accumulators, which can lead to undetected energy loss and environmental pollution.
Innovation Solution
A self-contained, depth-compensated expandable vessel system with a bidirectional valve and controller, using an expandable vessel with axial folds that can store and release hydraulic fluid energy while counteracting hydrostatic pressure, eliminating the need for springs and pistons, and preventing fluid leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a spring-charged accumulator is used for energy storage, then hydraulic fluid energy can be stored, but the spring may fail causing undetected loss of hydraulic fluid energy
Solution Approach 1:
The patent removes the spring component entirely from the accumulator system, replacing it with a flexible bladder mechanism. This extraction eliminates the failure mode associated with spring fatigue and breakage, ensuring that energy storage reliability is maintained without the risk of undetected energy loss from spring failure.
Solution Approach 2:
The flexible bladder automatically responds to pressure changes and depth variations without requiring external control or maintenance. The bladder's elastic properties enable it to self-regulate the energy storage and release process, eliminating the need for spring replacement or monitoring systems.
2Reliability
If a piston-based accumulator is used, then hydraulic fluid can be contained, but piston seal leakage causes hydraulic fluid to leak into the sea
Solution Approach 1:
The patent eliminates the piston and seal assembly from the accumulator design, replacing it with a flexible bladder containment system. This extraction removes the leakage pathway that would allow hydraulic fluid to escape into the marine environment, completely preventing fluid pollution while maintaining containment reliability.
Solution Approach 2:
The patent employs a flexible bladder as the containment element instead of a rigid piston with seals. The bladder's flexible membrane structure provides fluid containment without requiring sealing interfaces that could fail, eliminating the harmful leakage effect while maintaining the necessary containment function.
3Adaptability or versatility
If an accumulator is designed for deep ocean depths greater than 5,000 feet, then subsea deployment is enabled, but the structure must withstand extreme hydrostatic pressure
Solution Approach 1:
The patent utilizes a flexible bladder construction that can elastically deform under extreme hydrostatic pressure without structural failure. The flexible material allows the accumulator to accommodate pressure changes at depths greater than 5,000 feet while maintaining its containment function, enabling deep sea deployment without requiring overly robust rigid structures.
Solution Approach 2:
The patent designs the accumulator with materials and structural parameters specifically selected to withstand the extreme pressure conditions of deep ocean environments. The flexible bladder's elastic modulus and thickness are optimized to maintain structural integrity under hydrostatic pressures corresponding to depths exceeding 5,000 feet, enabling adaptability to deep sea conditions.
4Strength
If a rigid accumulator structure is used, then structural strength is maintained, but frictional losses increase and rapid expansion/contraction is hindered
Solution Approach 1:
The patent replaces rigid structural walls with a flexible bladder construction that allows for rapid expansion and contraction with minimal frictional resistance. The flexible material maintains sufficient structural strength to contain hydraulic pressure while enabling quick volume changes, thereby reducing energy losses and improving response time for energy storage and release operations.
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 system effectively stores and releases hydraulic fluid energy on demand, maintaining energy availability for subsea equipment while preventing fluid loss and pollution, even at extreme depths, with rapid expansion and contraction capabilities and minimal frictional losses.
Implementation Method 1
an expandable vessel with axial folds that can store and release hydraulic fluid energy while counteracting hydrostatic pressure
Implementation Method 2
The bidirectional valve can be in a first state that permits passage of the hydraulic fluid from the pressure source to the expandable vessel and in a second state that permits passage of the hydraulic fluid from the expandable vessel to the subsea equipment
Implementation Method 3
a self-contained, depth-compensated expandable vessel system... maintaining energy availability for subsea equipment while preventing fluid loss and pollution, even at extreme depths
Data Source
AI summary
A system for storing and releasing hydraulic energy having a controller, a pressure source, a bidirectional valve fluidly connected to the pressure source, an expandable vessel fluidly connected to the bidirectional valve having a plurality of axial folds between first and second ends, and a bidirectional port connected to the pressure source. As the plurality of axial folds expand, a contracted volume of pressure expands increasing stored hydraulic fluid energy in the expandable vessel. As the plurality of axial folds contract, the expanded volume reduces, releasing stored hydraulic fluid energy to nearby subsea equipment on demand as changes in hydraulic fluid energy requirements for the subsea equipment changes. Simultaneously, hydrostatic seawater pressure of seawater on the expandable vessel is counteracted with the hydrostatic pressure of fluid inside the expandable vessel.