# US 2025/0146906 A1 · Gear defect detection device and gear defect detection method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2025/0146906 A1 - Document ID: US20250146906A1 - Status: Published application - Kind: A1 - Application number: 18/838,076 - Filed: 2022-04-04 - Published: 2025-05-08 - Earliest claimed: 2022-04-04 - Assignees: Mitsubishi Electric Corporation - Applicants: Mitsubishi Electric Corporation - Inventors: Sachi ITAGAKI; Masashi ASUKA; Mototsugu KOZAKI - Web page: https://patentgrep.com/patent/US20250146906A1 ## CPC - G01M 13/021: Gearings - G01M 13/028: Acoustic or vibration analysis - G01M: TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR ## Abstract A gear defect detection device includes an acquisition unit that obtains a pulse signal from a sensor, where the pulse signal includes first signal sections and second signal sections alternating one after another, the first signal sections each represent a bottom portion of the gear, and the second signal sections each represent a top portion of the gear; and a calculation unit that determines, presence or absence of a defect of the gear on a basis of a ratio between the length of a first time period of a corresponding one of the first signal sections and the length of a second time period of a corresponding one of the second signal sections, and further determines the presence or absence of a defect of the gear using at least one of acceleration or jerk of an object that acts according to rotation of the gear. ## Claims ### Claim 1 A gear defect detection device comprising: an acquisition circuitry to obtain a pulse signal from a sensor for detecting top and bottom portions of a gear, the pulse signal including first signal sections and second signal sections alternating one after another, the first signal sections each representing a bottom portion of the gear, the second signal sections each representing a top portion of the gear; and a calculation circuitry to determine, using the pulse signal, presence or absence of a defect of the gear on a basis of a ratio between a length of a first time period of a corresponding one of the first signal sections and a length of a second time period of a corresponding one of the second signal sections, and to further determine the presence or absence of a defect of the gear using at least one of acceleration or jerk of an object that acts according to rotation of the gear in the corresponding one of the first signal sections and in the corresponding one of the second signal sections by comparison of the absolute value of the acceleration with the absolute value of the maximum acceleration or comparison of the absolute value of the jerk with the absolute value of maximum jerk. ### Claim 2 (depends on 1) The gear defect detection device according to claim 1, wherein the calculation circuitry performs a first determination to determine the presence or absence of a defect of the gear on a basis of the ratio between the length of the first time period and the length of the second time period, and the calculation circuitry further calculates a first speed of the object in the corresponding one of the first signal sections from the length of the first time period, calculates a second speed of the object in the corresponding one of the second signal sections from the length of the second time period, calculates a first acceleration of the object in the corresponding one of the first signal sections and a second acceleration of the object in the corresponding one of the second signal sections, and performs a second determination to determine the presence or absence of a defect of the gear by comparison of an absolute value of the first acceleration and an absolute value of the second acceleration each with an absolute value of a maximum acceleration predetermined for the object, the first acceleration being a change rate of the first speed, the second acceleration being a change rate of the second speed. ### Claim 3 (depends on 1) The gear defect detection device according to claim 1, wherein the calculation circuitry performs a first determination to determine the presence or absence of a defect of the gear on a basis of the ratio between the length of the first time period and the length of the second time period, and the calculation circuitry further calculates a first speed of the object in the corresponding one of the first signal sections from the length of the first time period, calculates a second speed of the object in the corresponding one of the second signal sections from the length of the second time period, calculates a first acceleration of the object in the corresponding one of the first signal sections and a second acceleration of the object in the corresponding one of the second signal sections, calculates a first jerk of the object in the corresponding one of the first signal sections and a second jerk of the object in the corresponding one of the second signal sections, and performs a second determination to determine the presence or absence of a defect of the gear by comparison of an absolute value of the first jerk and an absolute value of the second jerk each with an absolute value of a maximum jerk predetermined for the object, the first acceleration being a change rate of the first speed, the second acceleration being a change rate of the second speed, the first jerk being a change rate of the first acceleration, the second jerk being a change rate of the second acceleration. ### Claim 4 (depends on 1) The gear defect detection device according to claim 1, wherein the calculation circuitry performs a first determination to determine the presence or absence of a defect of the gear on a basis of the ratio between the length of the first time period and the length of the second time period, the calculation circuitry further calculates a first speed of the object in the corresponding one of the first signal sections from the length of the first time period, calculates a second speed of the object in the corresponding one of the second signal sections from the length of the second time period, calculates a first acceleration of the object in the corresponding one of the first signal sections and a second acceleration of the object in the corresponding one of the second signal sections, and performs a second determination to determine the presence or absence of a defect of the gear by comparison of an absolute value of the first acceleration and an absolute value of the second acceleration each with an absolute value of a maximum acceleration predetermined for the object, the first acceleration being a change rate of the first speed, the second acceleration being a change rate of the second speed, and the calculation circuitry still further calculates a first jerk of the object in the corresponding one of the first signal sections and a second jerk of the object in the corresponding one of the second signal sections, and performs a third determination to determine the presence or absence of a defect of the gear by comparison of an absolute value of the first jerk and an absolute value of the second jerk each with an absolute value of a maximum jerk predetermined for the object, the first jerk being a change rate of the first acceleration, the second jerk being a change rate of the second acceleration. ### Claim 5 (depends on 1) The gear defect detection device according to claim 1, wherein when the calculation circuitry has determined that the gear has a defect using any determination method as many times as a predetermined number of times in a predetermined time period, the calculation circuitry determines that the gear has been detected having a defect. ### Claim 6 A gear defect detection method for use in a gear defect detection device, the gear defect detection method comprising: obtaining, by an acquisition circuit, a pulse signal from a sensor for detecting top and bottom portions of a gear, the pulse signal including first signal sections and second signal sections alternating one after another, the first signal sections each representing a bottom portion of the gear, the second signal sections each representing a top portion of the gear; and determining, by a calculation circuitry, using the pulse signal, presence or absence of a defect of the gear on a basis of a ratio between a length of a first time period of a corresponding one of the first signal sections and a length of a second time period of a corresponding one of the second signal sections, and further determining, by the calculation circuitry, the presence or absence of a defect of the gear using at least one of acceleration or jerk of an object that acts according to rotation of the gear in the corresponding one of the first signal sections and in the corresponding one of the second signal sections by comparison of the absolute value of the acceleration with the absolute value of the maximum acceleration or comparison of the absolute value of the jerk with the absolute value of the maximum jerk. ### Claim 7 (depends on 6) The gear defect detection method according to claim 6, wherein in determining the presence or absence of a defect of the gear, the calculation circuitry performs a first determination to determine the presence or absence of a defect of the gear on a basis of the ratio between the length of the first time period and the length of the second time period, and the calculation circuitry further calculates a first speed of the object in the corresponding one of the first signal sections from the length of the first time period, calculates a second speed of the object in the corresponding one of the second signal sections from the length of the second time period, calculates a first acceleration of the object in the corresponding one of the first signal sections and a second acceleration of the object in the corresponding one of the second signal sections, and performs a second determination to determine the presence or absence of a defect of the gear by comparison of an absolute value of the first acceleration and an absolute value of the second acceleration each with an absolute value of a maximum acceleration predetermined for the object, the first acceleration being a change rate of the first speed, the second acceleration being a change rate of the second speed. ### Claim 8 (depends on 6) The gear defect detection method according to claim 6, wherein determining the presence or absence of a defect of the gear, calculation circuitry performs a first determination to determine the presence or absence of a defect of the gear on a basis of the ratio between the length of the first time period and the length of the second time period, and the calculation circuitry further calculates a first speed of the object in the corresponding one of the first signal sections from the length of the first time period, calculates a second speed of the object in the corresponding one of the second signal sections from the length of the second time period, calculates a first acceleration of the object in the corresponding one of the first signal sections and a second acceleration of the object in the corresponding one of the second signal sections, calculates a first jerk of the object in the corresponding one of the first signal sections and a second jerk of the object in the corresponding one of the second signal sections, and performs a second determination to determine the presence or absence of a defect of the gear by comparison of an absolute value of the first jerk and an absolute value of the second jerk each with an absolute value of a maximum jerk predetermined for the object, the first acceleration being a change rate of the first speed, the second acceleration being a change rate of the second speed, the first jerk being a change rate of the first acceleration, the second jerk being a change rate of the second acceleration. ### Claim 9 (depends on 6) The gear defect detection method according to claim 6, wherein determining the presence or absence of a defect of the gear, the calculation circuitry performs a first determination to determine the presence or absence of a defect of the gear on a basis of the ratio between the length of the first time period and the length of the second time period, the calculation circuitry further calculates a first speed of the object in the corresponding one of the first signal sections from the length of the first time period, calculates a second speed of the object in the corresponding one of the second signal sections from the length of the second time period, calculates a first acceleration of the object in the corresponding one of the first signal sections and a second acceleration of the object in the corresponding one of the second signal sections, and performs a second determination to determine the presence or absence of a defect of the gear by comparison of an absolute value of the first acceleration and an absolute value of the second acceleration each with an absolute value of a maximum acceleration predetermined for the object, the first acceleration being a change rate of the first speed, the second acceleration being a change rate of the second speed, and the calculation circuitry still further calculates a first jerk of the object in the corresponding one of the first signal sections and a second jerk of the object in the corresponding one of the second signal sections, and performs a third determination to determine the presence or absence of a defect of the gear by comparison of an absolute value of the first jerk and an absolute value of the second jerk each with an absolute value of a maximum jerk predetermined for the object, the first jerk being a change rate of the first acceleration, the second jerk being a change rate of the second acceleration. ### Claim 10 (depends on 6) The gear defect detection method according to claim 6, wherein determining the presence or absence of a defect of the gear, when the calculation circuitry has determined that the gear has a defect using any determination method as many times as a predetermined number of times in a predetermined time period, the calculation circuitry determines that the gear has been detected having a defect. ### Claim 11 (depends on 2) The gear defect detection device according to claim 2, wherein when the calculation circuitry has determined that the gear has a defect using any determination method as many times as a predetermined number of times in a predetermined time period, the calculation circuitry determines that the gear has been detected having a defect. ### Claim 12 (depends on 3) The gear defect detection device according to claim 3, wherein when the calculation circuitry has determined that the gear has a defect using any determination method as many times as a predetermined number of times in a predetermined time period, the calculation circuitry determines that the gear has been detected having a defect. ### Claim 13 (depends on 4) The gear defect detection device according to claim 4, wherein when the calculation circuitry has determined that the gear has a defect using any determination method as many times as a predetermined number of times in a predetermined time period, the calculation circuitry determines that the gear has been detected having a defect. ### Claim 14 (depends on 7) The gear defect detection method according to claim 7, wherein in determining the presence or absence of a defect of the gear, when the calculation circuitry has determined that the gear has a defect using any determination method as many times as a predetermined number of times in a predetermined time period, the calculation circuitry determines that the gear has been detected having a defect. ### Claim 15 (depends on 8) The gear defect detection method according to claim 8, wherein in determining the presence or absence of a defect of the gear, when the calculation circuitry has determined that the gear has a defect using any determination method as many times as a predetermined number of times in a predetermined time period, the calculation circuitry determines that the gear has been detected having a defect. ### Claim 16 (depends on 9) The gear defect detection method according to claim 9, wherein in determining the presence or absence of a defect of the gear, when the calculation circuitry has determined that the gear has a defect using any determination method as many times as a predetermined number of times in a predetermined time period, the calculation circuitry determines that the gear has been detected having a defect.