Hydraulic Sleeve Actuator Structure for High-Pressure Durability
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Solution Overview
Problem
Conventional pneumatic and hydraulic actuators have limitations in durability, particularly when used with high-pressure liquids, as they lack sufficient strength and resistance to withstand the pressures involved.
Innovation Solution
The development of an actuator with a cylindrical tube and a sleeve structure, where the tube's inner diameter, thickness, storage elastic modulus, and mesh aperture ratio of the sleeve's cords satisfy the formula 50≤E′×(t/r0)/A≤600, incorporating rubber layers with specific materials and fillers, and using cords made from high-strength fibers like aramid, to enhance durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a conventional pneumatic actuator with a rubber tube and sleeve is used, then the structure is simple and easy to manufacture, but the pressure resistance is low (only around 0.5 MPa) and durability is insufficient for high-pressure hydraulic applications
Solution Approach 1:
The patent applies composite materials by combining multiple rubber layers with different properties (polar and non-polar rubber layers) and incorporating fillers like carbon black and silica. This composite structure significantly enhances pressure resistance and durability while maintaining a relatively simple overall actuator design, resolving the contradiction between strength improvement and structural complexity.
Solution Approach 2:
The patent implements local quality by creating a multi-layered tube structure where each layer has specific properties tailored to its function. The inner layer uses non-polar rubber for oil resistance, while the outer layer uses polar rubber for durability. Fillers are strategically added to specific layers to enhance local strength and pressure resistance without complicating the entire structure.
2Strength
If the tube thickness is increased to improve pressure resistance, then strength improves, but the contraction rate and flexibility deteriorate
Solution Approach 1:
The multi-layer composite tube structure allows achieving high pressure resistance without excessive thickness increase. The combination of polar and non-polar rubber layers with optimized filler content provides strength enhancement while maintaining flexibility and contraction performance, resolving the trade-off between strength and ease of operation.
Solution Approach 2:
The patent optimizes the thickness and composition parameters of each rubber layer to achieve the desired balance. By carefully controlling the thickness of individual layers rather than uniformly increasing overall thickness, the actuator maintains high contraction rate while achieving sufficient pressure resistance for hydraulic applications.
3Reliability
If high-strength fibers like aramid are used in the sleeve to improve durability, then pressure resistance improves, but manufacturing complexity and cost increase
Solution Approach 1:
The patent uses aramid fibers in the sleeve as a composite material to dramatically improve durability and pressure resistance. The high strength-to-weight ratio of aramid allows creating a lightweight yet extremely durable sleeve that can withstand high hydraulic pressures, accepting increased manufacturing complexity as a trade-off for significant reliability improvement.
Solution Approach 2:
The sleeve is designed with locally optimized fiber arrangement and tension to achieve maximum durability where needed. The weaving pattern and fiber orientation are specifically tailored to handle the stress distribution in hydraulic actuation, ensuring high reliability while minimizing unnecessary manufacturing complexity in non-critical areas.
4Strength
If the mesh aperture ratio of the sleeve cords is decreased to improve pressure resistance, then strength improves, but the expansion movement capability deteriorates
Solution Approach 1:
The patent optimizes the mesh aperture ratio parameter of the sleeve cords to achieve the ideal balance between pressure resistance and expansion movement. By carefully selecting and adjusting this geometric parameter, the actuator maintains sufficient structural strength to withstand high pressures while preserving adequate expansion and contraction capability for effective actuation.
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 exhibits significantly improved durability, capable of operating over 8000 times with a contraction rate of ≥20% under 5 MPa pressure, outperforming conventional actuators in terms of strength and longevity.
Implementation Method 1
a cylindrical tube capable of expanding/contracting by hydraulic pressure
Implementation Method 2
the storage elastic modulus E′ (MPa) of the tube at 25° C.
Data Source
AI summary
An object of the present disclosure is to provide an actuator having even better durability than the conventional actuator. Specifically, an actuator has an actuator main body constituted of a cylindrical tube capable of expanding/contracting by hydraulic pressure and a sleeve for covering an outer peripheral surface of the tube, the sleeve having a cylindrical structure formed by cords woven to be disposed in predetermined directions, wherein: the inner diameter r0 (mm) of the tube, the thickness t (mm) of the tube, the storage elastic modulus E′ (MPa) of the tube at 25° C., and the mesh aperture ratio A of the cords constituting the sleeve in a pressurized state satisfy the following formula (1):50≤E′×(t/r0)/A≤600 (1).