High Temperature Piezo Buzzer with PZT Ceramic
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Solution Overview
Problem
Current piezoelectric buzzers used in personal alert safety systems (PASS) malfunction or melt at temperatures exceeding 175° F., compromising their ability to provide effective alerts in high-temperature fire situations.
Innovation Solution
A piezoelectric buzzer design featuring a vibrating layer and piezoelectric material with a Curie temperature above 260° C., combined with high-temperature polymers and alloys, ensuring operation and sound production at elevated temperatures, utilizing a PZT ceramic material with specific dopants and a composite perovskite crystal structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional piezoelectric buzzers with low Curie temperature PZT ceramic material are used, then they can operate at standard temperatures and produce adequate sound, but they malfunction or melt when exposed to temperatures exceeding 175° F.
Solution Approach 1:
The patent changes the Curie temperature parameter of the piezoelectric material from below 175° F. to above 260° C. by selecting high-temperature PZT ceramic materials with specific compositional ratios (0.94 ≤ x ≤ 0.99, 0.92 ≤ y ≤ 0.97, 0.45 ≤ z ≤ 0.55), enabling the buzzer to maintain piezoelectric properties at elevated temperatures
Solution Approach 2:
The patent uses composite material construction by combining high-temperature PZT ceramic material with metal or high-temperature polymer vibrating layers, creating a buzzer system that can withstand temperatures exceeding 260° C. while maintaining acoustic performance
2Temperature
If the piezoelectric material Curie temperature is increased to above 260° C., then the buzzer can operate in high-temperature environments, but the material selection and manufacturing become more complex
Solution Approach 1:
The patent establishes specific parameter ranges for the piezoelectric material composition (x, y, z values) that guarantee both high Curie temperature (>260° C.) and adequate piezoelectric performance (kp ≥ 0.5, k33 ≥ 1500, Qm ≥ 2000), simplifying material selection within defined boundaries
Solution Approach 2:
The patent optimizes specific regions of the material composition space by doping with particular elements (CeO2: 0.1-1.0 wt%, CuO: 0.1-2.0 wt%, Nb2O5: 1.0-5.0 wt%) to locally enhance piezoelectric properties while maintaining high-temperature stability
3Temperature
If high-temperature materials are used to withstand temperatures above 260° C., then the buzzer maintains structural integrity, but the cost of materials and manufacturing increases
Solution Approach 1:
The patent uses cost-effective dopants (CeO2, CuO, Nb2O5) in small quantities (0.1-5.0 wt% total) to achieve high-temperature performance, avoiding the need for expensive exotic materials while maintaining thermal resistance above 260° C.
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 the piezoelectric buzzer to maintain functionality and produce a sound pressure level of at least 80 dB at temperatures above 260° C., ensuring reliable operation in high-temperature environments.
Implementation Method 1
a piezoelectric material overlaying the vibrating layer, and electrical connections for connecting the piezoelectric material to a power source
Implementation Method 2
a piezoelectric material overlaying the vibrating layer
Data Source
AI summary
A piezoelectric buzzer includes a vibrating layer capable of withstanding temperatures in excess of 260° C. for at least five minutes while still maintaining its ability to vibrate and produce a buzzing sound at a level of at least 80 dB, and a high temperature piezoelectric material having a Curie temperature in excess of 260° C. and one or more of the following properties: a planar coupling coefficient (kp) of at least about 0.5; a longitudinal coupling coefficient (k33) of at least about 1500; and a mechanical quality factor (Qm) of at least about 2000. The piezo material may have a combination of these properties such that the product (kp2)(k33)(Qm) is at least about 1.5×106. The piezoelectric material may have a base formula of PbxSr(1-x)(Mn1/3Sb2/3)(1-y)(ZrzTi1-z)yO3 with x ranging from 0.95 to 0.99, y ranging from 0.92 to 0.97, and z ranging from 0.45 to 0.55, and may further include dopants in the amounts of about 0.4% CeO2, about 1% CuO, and about 4% Nb2O5.