SMA Actuator Insulation Member for Compact Spring Design
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Solution Overview
Problem
Existing shape memory alloy actuators face challenges in achieving stable performance and electrical insulation between the bias spring and the shape memory alloy wire, particularly when aiming for a reduction in actuator size, where a smaller diameter bias spring is required for improved spring performance.
Innovation Solution
A shape memory alloy actuator design featuring a shape memory alloy wire inserted through a hollow member, with an insulation member and an elastic member to prevent electrical contact between the wire and the bias spring, allowing for stable expansion and compression of the spring while maintaining insulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the diameter of the bias spring is reduced to achieve smaller actuator size, then the spring performance is improved, but electrical insulation between the bias spring and shape memory alloy wire becomes difficult to ensure
Solution Approach 1:
The patent introduces an insulation member as an intermediary component between the shape memory alloy wire and the bias spring. This insulation member is inserted through the bias spring and mechanically connects the movable element to the fixing element, providing electrical insulation while maintaining mechanical force transmission. This resolves the contradiction by enabling close spacing (reduced actuator size) while ensuring reliable electrical insulation.
2Volume of moving object
If the bias spring diameter is made small for compact actuator design, then space is saved, but the stability of spring expansion and compression deteriorates
Solution Approach 1:
The insulation member serves as a mediator that stabilizes the bias spring's operation. By being inserted through the bias spring and providing structural support, it prevents the spring from becoming too flexible or unstable when made compact, thus maintaining spring performance stability in a small-diameter configuration.
Solution Approach 2:
The patent creates a composite structure combining the bias spring and insulation member. This composite assembly allows the spring to maintain its functional stability while being compact, as the insulation member provides additional structural integrity to the small-diameter spring configuration.
3Reliability
If electrical insulation is implemented between the shape memory alloy wire and bias spring, then stable spring operation is achieved, but device complexity increases
Solution Approach 1:
The insulation member is designed to perform multiple functions simultaneously: it provides electrical insulation between the wire and spring, serves as a mechanical connector between the movable element and fixing element, and provides structural support to the compact bias spring. This multi-functionality reduces the need for separate components, thereby limiting the increase in device complexity.
Solution Approach 2:
The patent merges the insulation function with the mechanical connection function into a single insulation member component. This consolidation reduces the number of parts compared to having separate insulation elements and connectors, thus minimizing the increase in device complexity while achieving reliable electrical insulation.
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 ensures stable operation of the bias spring and reliable electrical insulation of the shape memory alloy wire, preventing power loss and enabling precise control of the movable element through resistance monitoring without electrical contact.
Implementation Method 1
A shape memory alloy changes its shape with transformation caused by a change in the temperature
Implementation Method 2
The shape memory alloy wire serving as a driving source of the actuator is heated by supplying electric power or current thereto
Implementation Method 3
an elastic member that is arranged between the movable element and the first hollow member and by which an external force is exerted on the movable element in a direction in which the shape memory alloy wire expands
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
An actuator has a shape memory alloy wire that contracts when heated by electric power supply and expands when cooled, whereby its length changes, a first hollow member through which the shape memory alloy wire is inserted, a movable element having an end mechanically connected to the shape memory alloy wire and movable relative to the first hollow member along a direction along which the length of the shape memory wire changes, an elastic member that is arranged between the movable element and the first hollow member and by which an external force is exerted on the movable element in a direction in which the shape memory alloy wire expands. In addition, an insulation member is joined to the movable element, a part of the insulation member is inserted in the first hollow member in a movable manner, and the shape memory alloy wire is connected to the end of the inserted part. Thus, the shape memory alloy wire is prevented from being in electrical contact with the elastic member.