SMA Wire Actuator Clamping Connection for Damage-Free Attachment
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Solution Overview
Problem
Existing connection methods for shape memory alloy wires in actuators for adjustable components, such as those in motor vehicles, often result in inadequate mechanical security and potential damage to the wire due to plastic deformation, which also affects heat distribution and reliability.
Innovation Solution
A connection element comprising a clamping wedge and sleeve with a press bushing, where the clamping force is divided into initial and additional forces through plastic deformation of the press bushing and tensile force, ensuring a secure, damage-free attachment of the wire, with features like slot-shaped recesses for tolerance compensation and conical clamping sections for enhanced clamping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional connection methods are used for shape memory alloy wires, then the wire can be attached to the actuator, but the mechanical connection is inadequate and the wire may be damaged due to plastic deformation
Solution Approach 1:
The connection element is divided into multiple functional sections: a press-fit section for initial damage-free attachment, and a clamping section for enhanced mechanical security. This segmentation allows each section to perform its specific function optimally without compromising the wire
Solution Approach 2:
The connection element utilizes elastic deformation (parameter change) of its material to create a radial clamping force. When subjected to axial tensile force, the connection element deforms elastically to generate increased clamping force on the wire, enhancing mechanical security without plastic deformation
2Reliability
If conventional connection methods are used, then the wire can be secured, but heat distribution is affected and reliability decreases
Solution Approach 1:
The connection element maintains the wire in an elastic deformation state rather than plastic deformation, which preserves the wire's thermal properties. The elastic clamping force is sufficient for mechanical security while minimizing thermal resistance at the connection interface
Solution Approach 2:
The connection element is designed as a sacrificial component that absorbs all deformation (elastic and plastic) while protecting the expensive shape memory alloy wire. The connection element can be replaced if needed, while the wire remains intact and reusable
3Ease of manufacture
If a simple connection method is used, then the manufacturing process is simple, but the mechanical security and clamping force are insufficient
Solution Approach 1:
The connection element is manufactured as an integrated piece with distinct press-fit and clamping sections, combining two functions in one component. This maintains manufacturing simplicity while achieving both damage-free attachment and enhanced mechanical security
Solution Approach 2:
The connection element merges the press-fit attachment function and the elastic clamping function into a single integrated component, eliminating the need for separate fasteners or complex assembly steps while providing robust mechanical security
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 provides a reliable, damage-free connection that maintains wire integrity and improves heat distribution, ensuring secure attachment and efficient operation of shape memory alloy actuators in adjustable components.
Implementation Method 1
A plastic deformation of the wall generates a first clamping force on the wire at at least one holding section formed by the inner surface, which connects the wire and the crimp sleeve by friction
Implementation Method 2
a tensile force induced in the wire in the axial direction clamps the wedge and the sleeve against each other in such a way that a second clamping force is generated on the wire in the receiving opening of the wedge, which further connects the wire and the wedge by friction
Implementation Method 3
Shape memory actuators are based on the shape memory effect of shape memory alloys. This effect is based on a crystallographically reversible martensite-austenite phase transformation that can be thermally excited. After deformation, elements of a shape memory alloy can be restored to a previously imprinted shape by the shape memory effect
Data Source
Figure 1
Figure 1a~1b
Figure 1c~1d
AI summary
The invention relates to an actuator (100) for a movable component, particularly a motor vehicle, comprising a wire (10) consisting of a shape-memory alloy, comprising a first end section (11) and a second end section (12) and extending over a variable length (L) in an axial direction (A), a control element (20) that can be moved between a first position (I) and a second position (II) in the axial direction (A), a floating bearing (30) by means of which the wire (10) is arranged such that it can move in the axial direction (A), a fixed bearing (33) by means of which the wire (10) is arranged such that it is stationary in the axial direction (A), at least one abutment (40, 45) connected to the floating bearing (30) or the fixed bearing (33) and provided with a through-opening (41, 46) for the wire (10) and a bearing surface (42, 47) designed to transmit a force in the radial direction (R), and at least one elastically deformable connection element (60, 65) comprising a receiving opening (61, 66) for the wire (10), which has a variable diameter (DA1, DA2) and in which the wire (10) is clamped in the region of the first end section (11) or the second end section (12), and a contact surface (62, 67) applied to the bearing surface (42, 47) of the abutment (40, 45). By reducing the length (L) of the wire (10), a tensile force can be transmitted from the wire (10) to the connection element (60, 65), by means of which the control element (20) can be moved from the first position (I) to the second position (II) and the contact surface (62, 67) can be braced against the bearing surface (42, 47) in such a way that the abutment (40, 45) causes a counterforce to act on the connection element (60, 65) by means of a component acting in the radial direction (R), by means of which the diameter (DA1, DA2) of the receiving opening (61, 66) can be reduced in order to hold the wire (10) in the connection element (60, 65).