Piezoelectric Weft-Braking Device for Yarn Feeders
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Solution Overview
Problem
Existing weft-braking devices for yarn feeders with stationary drums, particularly those using electromagnetic actuators, suffer from slow reaction times and high energy consumption due to heavyweight structures and high current requirements.
Innovation Solution
A weft-braking device incorporating a static braking mechanism with a hollow frustoconical member and an active braking mechanism using counterposed braking plates with a piezoelectric bending actuator to modulate yarn tension, allowing for faster reaction times and reduced energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If electromagnetic actuators are used in weft-braking devices, then braking force can be controlled, but reaction time becomes slow and energy consumption increases
Solution Approach 1:
The patent replaces the electromagnetic actuator system with a piezoelectric actuator system. The piezoelectric actuator converts electrical signals directly to mechanical displacement through the piezoelectric effect, eliminating the need for electromagnetic coils and heavy magnetic components. This substitution reduces the system's moment of inertia significantly, enabling much faster reaction times while maintaining precise braking force control through voltage modulation.
Solution Approach 2:
The patent changes the actuation mechanism from electromagnetic to piezoelectric, fundamentally altering the physical parameter of response time. The piezoelectric material responds to electrical signals almost instantaneously (microsecond range), compared to the millisecond response of electromagnetic systems. This parameter change directly resolves the contradiction by achieving both controlled braking force and fast reaction time.
2Power
If electromagnetic actuators are used in weft-braking devices, then braking force can be controlled, but energy consumption increases due to high current requirements
Solution Approach 1:
The patent substitutes the high-power electromagnetic actuator with a low-power piezoelectric actuator. Piezoelectric materials generate mechanical strain in response to applied electric fields with extremely high efficiency, requiring minimal electrical energy. The braking force is controlled by modulating the voltage applied to the piezoelectric actuator, achieving precise control with energy consumption orders of magnitude lower than electromagnetic systems.
Solution Approach 2:
The patent changes the energy consumption parameter by transitioning from electromagnetic to piezoelectric actuation. The piezoelectric effect operates with very high energy efficiency, converting electrical energy directly to mechanical work with minimal losses. This parameter change resolves the contradiction by maintaining braking force control capability while dramatically reducing energy consumption.
3Power
If a movable plate made of magnetic material is used in electromagnetic braking systems, then braking force can be adjusted, but the heavyweight structure increases inertia and slows down system reactivity
Solution Approach 1:
The patent replaces the heavy magnetic movable plate with a lightweight piezoelectric actuator assembly. The piezoelectric actuator generates the necessary braking force through material deformation rather than requiring a heavy magnetic plate for force generation. This substitution dramatically reduces the mass of moving components, lowering the moment of inertia and enabling faster acceleration and deceleration of the movable element, thus resolving the contradiction between adjustable braking force and system reactivity.
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 achieves significantly faster reaction times, up to one order of magnitude faster than conventional electromagnetic systems, while reducing energy consumption by utilizing piezoelectric actuators that apply precise control over yarn tension with lower current requirements.
Implementation Method 1
a piezoelectric actuator, which transforms electrical energy to mechanical energy in order to move the second braking plate in a direction towards the first braking plate
Implementation Method 2
the yarn unwinding from the drum radially runs between two counterposed annular plates which are coaxially arranged in front of the drum and are biased against each other in order to brake the yarn by friction
Data Source
Figure 1~3
Figure 4~5
Figure 6~7
AI summary
The weft-braking device comprises a first annular plate (36) coaxially supported in front of the delivery end of a stationary drum (12) of a yarn feeder (10), and a second annular plate (44) which is coaxially biased against the first annular plate (36) by driving means (46). The yarn (Y) is adapted to run between the annular plates (36, 44) in order to receive a braking action by fricton. The driving means comprise at least one piezoelectric actuator (76), which is deformable in response to a voltage applied thereto and has a movable operative end (76a) which is operatively connected to the second annular plate (44) and a stationary operative end (76b) which is anchored to a stationary support (52).