SMA Lever Linear Drive Without Complex Coupling Mechanisms
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Solution Overview
Problem
Existing linear drives using shape memory alloy elements are complex and costly, with high maintenance requirements and susceptibility to faults, particularly when coupling mechanisms are involved, limiting their service life and efficiency.
Innovation Solution
A linear drive design featuring a lever element, a rod element, and a shape memory alloy element with a restoring element, where the shape memory alloy element exerts a tensile force to tilt the lever, creating a non-positive connection with the rod element, allowing for translational movement without complex couplings, and the restoring element ensures efficient movement and self-adjustment for wear compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If coupling mechanisms are used in linear drives with shape memory alloy elements, then the linear drive can achieve translational movement, but the device complexity and maintenance requirements increase significantly
Solution Approach 1:
The patent removes the complex coupling mechanism from the system entirely. Instead of using a separate coupling mechanism to transfer motion, the shape memory alloy element is directly connected to the lever element, which in turn is directly connected to the rod element. This extraction of the coupling mechanism eliminates the associated maintenance requirements and fault susceptibility while maintaining the essential translational movement function.
Solution Approach 2:
The patent merges the functions of the shape memory alloy element, lever element, and rod element into a directly connected system. The shape memory alloy element's contraction directly tilts the lever element, which directly moves the rod element along its axis. This merging eliminates intermediate coupling components and simplifies the overall construction while achieving the desired linear motion.
2Productivity
If coupling mechanisms are used in linear drives, then movement can be transmitted, but the susceptibility to faults and maintenance outlay increase
Solution Approach 1:
The coupling mechanism is completely removed from the system. The shape memory alloy element is directly connected to the lever element, eliminating the coupling mechanism that would otherwise be a source of faults and maintenance requirements. This direct connection maintains movement efficiency while significantly improving reliability.
3Reliability
If complex coupling mechanisms are used, then the linear drive can function, but the manufacturing cost and maintenance cost increase
Solution Approach 1:
The patent extracts and removes the complex coupling mechanism from the system. By directly connecting the shape memory alloy element to the lever element and the lever element to the rod element, the design eliminates costly coupling components and simplifies manufacturing while maintaining functional reliability.
4Productivity
If the shape memory alloy element is continuously shortened to maintain connection, then the rod element moves continuously, but energy consumption increases
Solution Approach 1:
The patent employs periodic action through the four-state cycle of the shape memory alloy element. The element is shortened in discrete steps (first state to second state for movement initiation, second state to third state for movement execution) rather than continuously. This periodic shortening, combined with the mechanical advantage of the lever element and bearing element friction, achieves continuous rod element movement while minimizing energy consumption.
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 design achieves reliable, long-lasting, and cost-effective translational movement with minimal maintenance by using the shape memory alloy element's tensile force and restoring element's counterforce, ensuring efficient conversion of energy into movement while adapting to wear and reducing the need for complex couplings.
Implementation Method 1
a shape memory alloy element (28) extending along a first axis (26), wherein a first end (30) of the shape memory alloy element (28) is connected to the first portion (16), a second end (32) of the shape memory alloy element (28) opposite the first end (30) is connected in a stationary manner to a first fixed bearing (34), and the shape memory alloy element (28) is designed to exert a tensile force acting along the first axis (26) on the lever element (12) when electrical power is applied
Implementation Method 2
the bearing element (24) supports the rod element (20), the bearing element (24) being designed to allow a movement of the rod element (20) along a rod axis (22) and to block a movement perpendicular to the rod axis (22)
Data Source
AI summary
A linear drive comprises: a lever having a through bore; a rod which extends through the bore; a bearing supporting the rod; a shape memory alloy connected to the lever and a first fixed bearing, the shape memory alloy exerting a tensile force on the lever when electrical power is applied; and a restoring element connected to the lever and a second fixed bearing, the restoring element exerting a restoring force on the lever and counter to the tensile force. In a first state, the lever is tilted making a non-positive connection between the lever and the rod. In a second state the lever is displaced in parallel to and in the direction of the tensile force. In a third state the lever is tilted back releasing the non-positive connection. In a fourth state, the lever is displaced in parallel to and in the direction of the restoring force.