Multi-Material Fluid Actuator for Lightweight Pressure Resistance
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Solution Overview
Problem
Existing fluid actuators are heavy due to the use of rigid materials like stainless steel, making it difficult to reduce their weight while maintaining necessary rigidity for pressure and impact resistance.
Innovation Solution
The fluid actuator design incorporates a cylinder with wall portions made of iron-based alloys for high rigidity near the mounting portion and aluminum alloys for the radially outer side, along with a piston rod of iron-based alloy, and a manifold made of aluminum alloy to reduce weight, and features a unique partitioning of fluid chambers with different cross-sectional areas to stabilize the piston rod.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the cylinder and other members are made of highly rigid material such as stainless steel to withstand pressure and external impacts, then the strength and rigidity are improved, but the weight increases significantly
Solution Approach 1:
The patent applies different materials to different parts of the cylinder based on their specific functional requirements. The mounting portion and axial wall portions that require high rigidity are made of iron-based alloy, while the radial wall portions that experience lower pressure are made of aluminum alloy. This local differentiation allows the actuator to maintain necessary strength while reducing overall weight.
Solution Approach 2:
The patent uses a composite construction where the cylinder is formed by combining iron-based alloy and aluminum alloy materials. The iron-based alloy provides structural integrity and pressure resistance at critical locations, while the aluminum alloy reduces weight in non-critical areas. This composite approach resolves the contradiction between strength and weight.
2Strength
If the mounting portion and axial wall portions are made of iron-based alloy to maintain high rigidity, then the strength is improved, but the weight increases
Solution Approach 1:
The patent specifically designates the mounting portion and axial wall portions to be made of iron-based alloy only where high rigidity is required for mounting and pressure resistance. The radial wall portions are made of lighter aluminum alloy, creating a localized strength solution that minimizes overall weight while maintaining necessary rigidity at critical locations.
3Weight of moving object
If the radial wall portions are made of aluminum alloy to reduce weight, then the weight is reduced, but the rigidity may be insufficient for high pressure areas
Solution Approach 1:
The patent recognizes that radial wall portions experience lower pressure compared to axial wall portions and the mounting area. Therefore, it is acceptable to use lighter aluminum alloy for radial walls while maintaining iron-based alloy for axial walls and mounting portions. This local quality differentiation allows weight reduction without compromising the rigidity where it is most needed.
4Speed
If the piston rod moves without fluid flow into or out of partition chambers, then the response speed is improved, but the piston rod may oscillate due to unbalanced forces
Solution Approach 1:
The patent introduces asymmetry in the cross-sectional areas of partition chambers to create a balancing effect. By making the cross-sectional areas of the first and second partition chambers different, the patent creates unequal forces that can counteract oscillations of the piston rod during rapid movement, thereby improving stability without sacrificing response speed.
Solution Approach 2:
The patent changes the geometric parameter (cross-sectional area) of the partition chambers to achieve force balance. By adjusting the cross-sectional areas of the first and second partition chambers to be different, the patent modifies the pressure distribution and force balance on the piston rod, preventing oscillation during high-speed operation.
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
This design achieves a lightweight fluid actuator with enhanced stability and reduced oscillation of attached objects, such as aircraft flaps, by distributing forces effectively across the piston rod and maintaining desired volumes within the fluid chambers.
Implementation Method 1
the piston rod being configured to reciprocate in the axial direction in accordance with pressures in the plurality of fluid chambers
Data Source
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AI summary
One object is to reduce a weight of a fluid actuator. The fluid actuator (10) includes: a cylinder (20) having an inner space and a first mounting portion (22z), the inner space being partitioned into a first fluid chamber (20A) and a second fluid chamber (20B), the first mounting portion (22z) being disposed on an end portion of the cylinder (20) on an axial direction A side; and a piston rod (30) configured to reciprocate in accordance with pressures in the fluid chambers. A wall portion defining the first fluid chamber (20A) in the cylinder (20) is made of an iron-based alloy. A wall portion defining the second fluid chamber (20B) in the cylinder (20) is made of an aluminum alloy. The piston rod (30) is made of an iron-based alloy.