Piezoelectric Pump Insulation Structure for Low-Voltage Household Use
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Solution Overview
Problem
Existing piezoelectric pumps used in household appliances face efficiency reduction due to the addition of insulating materials on metal membranes, especially when operating at low excitation voltages like those found in the domestic electrical network in countries such as the USA, and must comply with stringent UL safety standards.
Innovation Solution
A piezoelectric pump design featuring a metal membrane with a first flame-retardant insulating layer and two thinner insulating layers, allowing direct voltage supply from the domestic electrical network without an isolation transformer, maintaining membrane flexibility and efficiency while adhering to UL standards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a layer of insulating material is added to the metal membrane, then electrical insulation is improved, but pump performance deteriorates due to reduced membrane vibration amplitude
Solution Approach 1:
The insulating layer is divided into three distinct layers with different thicknesses and properties: a first layer (60 μm) with flame retardant properties, and two additional thinner layers (20 μm each) without flame retardant properties. This segmentation allows the membrane to maintain sufficient flexibility for effective pumping while providing the required electrical insulation and meeting safety standards.
Solution Approach 2:
Different regions of the insulating structure have different properties: the first layer provides flame retardancy and thicker insulation where needed, while the additional layers provide supplementary insulation with minimal thickness to preserve membrane flexibility. This local differentiation optimizes both safety and performance.
2Device complexity
If excitation voltage is reduced to match domestic network voltage, then device complexity is reduced, but pump efficiency deteriorates
Solution Approach 1:
The piezoelectric actuator is designed to operate efficiently at low voltages (90-120 V) by optimizing its electrical and mechanical parameters. The actuator's piezoelectric coefficients, electrode configuration, and resonant frequency are tuned to maximize vibration amplitude and pumping efficiency at domestic network voltages, eliminating the need for high-voltage transformers while maintaining adequate performance.
3Stability of the object's composition
If thinner insulating layers are used, then membrane flexibility is improved, but electrical insulation deteriorates
Solution Approach 1:
The insulating structure is segmented into three layers: a substantial first layer (60 μm) that provides the primary electrical insulation and flame retardancy, and two additional thinner layers (20 μm each) that provide supplementary insulation. This segmentation ensures total insulation performance while keeping individual thinner layers flexible.
Solution Approach 2:
The insulating structure uses a composite of multiple materials with different properties: the first layer uses material with flame retardant properties, while the additional layers use materials optimized for flexibility and supplementary insulation. This composite approach achieves both electrical insulation and membrane flexibility requirements.
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 maintains pump efficiency and compliance with UL standards, ensuring effective fluid discharge and steam production with a constant flow rate, even at low supply voltages.
Implementation Method 1
a piezoelectric actuator (13) provided for moving the membrane and discharging a fluid from the pumping chamber by modifying the volume of the pumping chamber under the action of the piezoelectric actuator
Implementation Method 2
the internal face of the metallic membrane is covered with at least a first electrically insulating layer having flame retardant properties and two additional electrically insulating layers
Data Source
Figure 1~2
Figure 3
AI summary
The invention relates to an electric household appliance comprising a pump having a pumping chamber (11) including a movable wall formed by a diaphragm (12) made of an electrically conductive material comprising an inner surface covered with at least one layer (21) made of an electrically insulating material, and an outer surface, in contact with a piezoelectric actuator (13), characterized in that power is supplied to said piezoelectric actuator (13) by the voltage of a domestic power grid without inserting an insulation transformer therebetween, and in that said inner surface of the metal diaphragm (12) is covered by at least one first electrically insulating layer (21), having flame retardant properties, and by two additional electrically insulating layers (22, 23) of a lower thickness.