Piezoelectric Selection Device for Weaving Loom Dobby Actuation
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Solution Overview
Problem
Existing selection devices for weaving loom dobbies are bulky and complex, requiring substantial electromagnets and metal armatures, and often feature fragile piezoelectric elements that are prone to breakage and limited in movement range.
Innovation Solution
A selection device with a rotatable selector and a piezoelectric actuating element, where the axis of rotation is positioned closer to a fixed end than the selector, allowing for a longer lever arm and reduced direct interaction with the main shaft, enabling larger amplitude movement and reduced risk of breakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an electromagnet with metal armature is used to control the selection device, then the dobby can be actuated, but the device becomes bulky and complex
Solution Approach 1:
The patent replaces the electromagnet with metal armature system with a piezoelectric actuator. The piezoelectric element directly converts electrical signals into mechanical displacement to position the selector, eliminating the need for electromagnetic fields, metal armatures, and associated mechanical linkages. This substitution dramatically reduces device complexity and size while maintaining reliable control of the dobby actuation.
Solution Approach 2:
The patent extracts and removes the bulky electromagnet and metal armature components from the selection device. By taking out these unnecessary elements and retaining only the essential piezoelectric actuator and selector mechanism, the design achieves significant simplification and compactness while preserving the core function of selectively positioning the tilting member.
2Ease of operation
If the piezoelectric element is in direct contact with the selector, then the selector can be actuated, but the piezoelectric element is fragile and prone to breakage
Solution Approach 1:
The patent introduces an intermediary mechanism between the piezoelectric element and the selector. The piezoelectric element actuates a lever or link that indirectly positions the selector, rather than being in direct contact. This intermediary structure protects the fragile piezoelectric element from direct mechanical stress and contact wear while still achieving the desired selector positioning function.
Solution Approach 2:
The patent segments the actuation mechanism into separate functional components: the piezoelectric element, the lever/link mechanism, and the selector. This segmentation allows the piezoelectric element to perform its precise actuation function while being physically separated from the selector, reducing the risk of breakage and extending durability.
3Manufacturing precision
If the selector has limited movement range, then the piezoelectric element deformation is constrained, but the control capability for certain dobbies is insufficient
Solution Approach 1:
The patent employs a dynamic lever mechanism that amplifies the movement range of the selector. The lever arm length and pivot points are designed to transform the small displacement from the piezoelectric element into a larger angular movement of the selector. This dynamic mechanical advantage allows the selector to achieve sufficient movement range for controlling various dobby configurations while maintaining precise positioning control.
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 results in a smaller, simplified design that amplifies the movement of the selector, enhancing control over the dobby while minimizing the risk of piezoelectric element damage and eliminating the need for precise air gap adjustments.
Implementation Method 1
an actuating element of a piezoelectric nature, making it possible to actuate the selector
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
The device (3) has a selector (5) for selectively positioning tilting members (17, 18), and an actuating element (7) for actuating the selector, where the actuating element is piezoelectric in nature. The selector is rotated with respect to a support member (22) for supporting the selector. A rotation axis (X21) of the selector is located closer to a fixed end (74) of the actuating element. Stop parts (S17, S18) limit movements of the selector, where each stop part is arranged on the tilting members.