# US 12,181,441 B1 · Rapid measuring device and measuring method for permanent magnet failure temperature > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,181,441 B1 - Document ID: US12181441B1 - Status: Granted - Kind: B1 - Application number: 18/605,794 - Filed: 2024-03-14 - Granted: 2024-12-31 - Earliest claimed: 2024-01-26 - Assignees: China Jiliang University - Applicants: China Jiliang University - Inventors: Hangfu Yang; Qiong Wu; Xiukun Hu; Minxiang Pan; Jieyang Fang; Hongliang Ge - Web page: https://patentgrep.com/patent/US12181441B1 ## CPC - G01N 27/72: by investigating magnetic variables - G01J 5/48: Thermography; Techniques using wholly visual means - G01N 1/44: Sample treatment involving radiation, e.g. heat - G01J 2005/0077: {Imaging} - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) - G01J: MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY (light sources F21, H01J, H01K, H05B; investigating properties of materials by optical means G01N) ## Abstract The present disclosure discloses a rapid measuring device and a measuring method for permanent magnet failure temperature. The device includes a measurement system (1), an infrared thermal imager (2), a vacuum Hall probe (3) and a laser heating device (4). A permanent magnet (5) is used as a sample. These components work together to achieve rapid and accurate measurement of the failure temperature of the permanent magnet sample (5). The present disclosure uses light heating, infrared thermal imaging and surface magnetic field measurement. The heating speed is fast, the temperature measurement is accurate, and the failure temperature measurement of large permanent magnet materials can be achieved. ## Claims ### Claim 1 A rapid measuring device for permanent magnet failure temperature, comprising: a measurement system (1) configured with a computer and a connector, wherein the computer is connected to an infrared thermal imager (2), a vacuum Hall probe (3) and a laser heating device (4) through the connector; the infrared thermal imager (2) configured to: monitor and record temperature changes of a permanent magnet sample (5) in real time, and transmit the recorded temperature changes to the computer; the vacuum Hall probe (3) configured to: measure magnetic field changes of the permanent magnet sample (5) during heating, and transmit the measured magnetic field changes to the computer; and the laser heating device (4) configured to control laser output energy for heating the permanent magnet sample (5); wherein the computer is configured to: obtain a change curve of magnetic field and temperature of the permanent magnet sample (5) by analyzing the recorded temperature changes from the infrared thermal imager (2) and the measured magnetic field changes from the vacuum Hall probe (3); calculate a first derivative with the change curve of magnetic field and temperature to obtain a curve of first derivative and temperature; and determine a failure temperature of the permanent magnet sample (5) based on the curve of first derivative and temperature, wherein the failure temperature is a temperature corresponding to a starting point of maximum trough of the curve of first derivative and temperature. ### Claim 2 (depends on 1) The rapid measuring device for permanent magnet failure temperature according to claim 1, wherein the laser heating device (4) comprises a laser source and a power controller configured to control laser energy output, and the laser heating device (4) has a laser output energy range from 1 mW to 1000 W. ### Claim 3 (depends on 1) The rapid measuring device for permanent magnet failure temperature according to claim 1, wherein the laser heating device (4) has an adjustable laser spot diameter ranging from 0.5 cm to 2 cm. ### Claim 4 (depends on 1) A measuring method using the rapid measuring device according to claim 1, comprising: step 1: turning on the laser heating device (4), adjusting a power controller of the laser heating device (4) to adjust a heating laser energy to less than 1 mW, focusing a laser on a surface of the sample (5), and placing the vacuum Hall probe (3) close to a laser spot; step 2: fixing the vacuum Hall probe (3) and using the infrared thermal imager (2) to measure the temperature changes of the permanent magnet sample (5) at the laser spot on the surface; step 3: adjusting the power controller of the laser heating device (4) to gradually increase a temperature of the laser spot on the permanent magnet sample (5), and using the vacuum Hall probe (3) to measure the magnetic field changes near the laser spot on the sample (5) while recording the temperature changes at the corresponding laser spot with the infrared thermal imager; and step 4: obtaining, through the measurement system (1), the change curve of magnetic field and temperature of the permanent magnet sample (5) by analyzing the temperature changes recorded by the infrared thermal imager (2) and the magnetic field changes measured by the vacuum Hall probe (3), calculating, through the measurement system (1), the first derivative with the change curve of magnetic field and temperature to obtain the curve of first derivative and temperature, and determining, through the measurement system (1), the failure temperature of the permanent magnet sample (5) based on the curve of first derivative and temperature. ### Claim 5 (depends on 4) The measuring method according to claim 4, wherein the laser spot in step 1 has a diameter ranging from 0.5 cm to 2 cm, and a distance between the vacuum Hall probe and the laser spot ranges from 1 cm to 5 cm. ### Claim 6 (depends on 5) The measuring method according to claim 5, wherein the laser spot has a diameter of 1 cm, and the distance between the vacuum Hall probe and the laser spot is 1.5 cm.