Appliance Door Locking Bar Using Shape Memory Wire Actuation
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Solution Overview
Problem
Conventional door locking devices for domestic appliances are complex, large, and require long reaction times, making them difficult to assemble, install, and noisy, with existing solutions not meeting the need for fast, simple, and compact designs.
Innovation Solution
A locking device utilizing a linear shape memory wire connected to a locking bar element and a return spring, allowing for fast and noiseless movement between engaged and disengaged positions, with a simple structure and small outer dimensions, and incorporating a silicone sleeve for enhanced cooling and ventilation openings for efficient heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional actuation systems (wax electro-thermal motor, solenoid, or stepper motor) are used, then the locking device can provide sufficient force, but the reaction time is long and the structure is complex
Solution Approach 1:
The patent replaces conventional mechanical actuation systems (wax electro-thermal motor, solenoid, or stepper motor) with a shape memory alloy wire that directly actuates the locking bar element. This substitution eliminates complex mechanical components while achieving fast reaction time through the direct thermal-mechanical response of the shape memory alloy.
Solution Approach 2:
The patent changes the actuation mechanism from electrical-mechanical conversion to thermal-mechanical conversion using shape memory alloy. By applying electrical current to heat the alloy wire, it undergoes a phase transformation that directly produces mechanical motion, achieving both simplicity and speed.
2Force
If conventional actuation systems are used, then sufficient force can be provided, but the outer dimensions become large
Solution Approach 1:
The patent extracts only the essential actuation function from complex motor assemblies, using a thin shape memory alloy wire that provides sufficient force through direct thermal expansion and phase transformation. This eliminates unnecessary mechanical components and reduces the overall volume of the actuation system.
3Reliability
If conventional actuation systems are used, then the locking device can function reliably, but the assembling and installation becomes complicated
Solution Approach 1:
The patent segments the locking device into modular components: a main body, a locking bar element, and a shape memory alloy wire. This segmentation allows each component to be manufactured independently and assembled through simple connection, greatly facilitating assembly and installation while maintaining reliability.
4Ease of operation
If conventional actuation systems are used, then the locking device can operate, but the movement produces noise
Solution Approach 1:
The patent replaces mechanical actuation systems that produce noise through moving parts and friction with a shape memory alloy-based system. The alloy wire actuates the locking bar element through direct thermal-mechanical transformation without mechanical contact, eliminating noise during 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
The solution enables fast engagement and disengagement of the door, reduced installation complexity, and noiseless operation, with a compact design that can withstand high temperatures and is energy-efficient, while maintaining safety features like preventing door opening during pyrolytic cleaning or by children.
Implementation Method 1
a shape memory wire (26) forms an electric actuator for the locking bar element (14). The first electric terminal (18) and the second electric terminal (20) are provided for the supply with electrical power of the shape memory wire (26). A change in length of the shape memory wire (26) effects pivoting of the locking bar element (14) between the engaged and disengaged positions
Implementation Method 2
ventilation openings (105) in the main body (10) and/or in the cover element (12) for efficient heat dissipation
Implementation Method 3
ventilation openings (105) in the main body (10) and/or in the cover element (12) for efficient heat dissipation
Data Source
Figure 1~2
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Figure 4
AI summary
A locking device for a door of a domestic appliance, wherein - the locking device comprises a main body (10), - the locking device comprises a locking bar element (14) supported pivoting in and/or at the main body (10), - the locking bar element (14) is pivoting between an engaged position and a disengaged position, - the locking bar element (14) is engageable and disengageable with a corresponding counterpart, - the locking device comprises a shape memory wire (26), - the locking device comprises at least one means (18, 20) for supplying the shape memory wire (26) with electric current, - the electric current through the shape memory wire (26) effects a movement of the locking bar element (14) to the disengaged position, - the locking device comprises a return spring element (30) interconnected between the locking bar element (14) and the main body (10), and - the return spring element (30) effects a movement of the locking bar element (14) to the engaged position, wherein the shape memory wire (26) extends lineally and connects the locking bar element (14) to the main body (10), wherein the locking bar element (14) includes a lever arm (28), at which the shape memory wire (26) is fastened, so that a change in length of said shape memory wire (26) directly effects pivoting of the locking bar element (14) between the engaged and disengaged positions.