# US 9,752,956 B2 · Monitoring system for predicting gearbox lifespan > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,752,956 B2 - Document ID: US9752956B2 - Status: Granted - Kind: B2 - Application number: 14/642,652 - Filed: 2015-03-09 - Published: 2016-09-15 - Granted: 2017-09-05 - Earliest claimed: 2015-03-09 - Assignees: Caterpillar Inc. - Applicants: Caterpillar Inc. - Inventors: Marvin Grendel McKimpson; Richard Andrew Carpenter - Web page: https://patentgrep.com/patent/US9752956B2 ## CPC - G01M 13/021: Gearings - G01N 33/2858: {Metal particles} - G01N 3/56: Investigating resistance to wear or abrasion - G01N 15/02: Investigating particle size or size distribution (by measuring osmotic pressure G01N7/10; investigating sedimentation of particle suspensions G01N15/04; investigating individual particles G01N15/10) - G01N 15/06: Investigating concentration of particle suspensions (by weighing G01N5/00; investigating sedimentation of particle suspensions G01N15/04; investigating individual particles G01N15/10) - G01N 33/2888: {Lubricating oil characteristics, e.g. deterioration (lubricating properties G01N33/30)} - G01N 2015/0053: {in liquids, e.g. trouble} - G01M: TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR - 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) ## Abstract A monitoring system for a gearbox containing a lubricant is disclosed. The monitoring system may include a first sensor configured to measure a concentration of debris particles in the lubricant, a second sensor configured to generate data indicative of a deterioration of the gearbox, and a controller in communication with the first and second sensors. The controller may be configured to estimate a concentration of debris particles in the lubricant based on the data from the second sensor using a mathematical function, and estimate a remaining useful life of the gearbox based on a difference between concentration of debris particles measured by the first sensor and concentration of debris particles estimated to be in the lubricant. ## Claims ### Claim 1 A monitoring system for a gearbox containing a lubricant, the monitoring system comprising: a first sensor configured to measure a concentration of debris particles in the lubricant; a second sensor configured to generate data indicative of a deterioration of the gearbox; and a controller in communication with the first and second sensors, the controller being configured to: estimate a concentration of debris particles in the lubricant based on the data from the second sensor using a mathematical function; estimate a remaining useful life of the gearbox based on a difference between the concentration of debris particles measured by the first sensor and the concentration of debris particles estimated to be in the lubricant over a period of time; and correct the mathematical function when the difference between the concentration of debris particles measured by the first sensor and the concentration of debris particles estimated to be in the lubricant over a period of time is above a first threshold difference and below a second threshold difference. ### Claim 2 (depends on 1) The monitoring system of claim 1, wherein the controller is configured to estimate the remaining useful life of the gearbox using the mathematical function when the difference between the concentration of debris particles measured by the first sensor and the concentration of debris particles estimated to be in the lubricant over a period of time is below a threshold difference. ### Claim 3 (depends on 1) The monitoring system of claim 1, wherein the controller is further configured to determine that the lubricant or a gearbox component has been replaced when the concentration of debris particles measured by the first sensor is less than the concentration of debris particles estimated to be in the lubricant by at least a threshold difference over a period of time. ### Claim 4 (depends on 3) The monitoring system of claim 3, wherein: the first sensor is further configured to measure a size of debris particles in the lubricant; and the controller is further configured to determine when a gearbox component has been replaced based on the size of the debris particles in the lubricant. ### Claim 5 (depends on 1) The monitoring system of claim 1, wherein the controller is further configured to determine a probability of a gearbox component failure when the concentration of debris particles measured by the first sensor is greater than the concentration of debris particles estimated to be in the lubricant by at least a threshold difference over a period of time. ### Claim 6 (depends on 5) The monitoring system of claim 5, wherein: the first sensor is further configured to determine a size of debris particles in the lubricant; and the controller is further configured to determine the probability of a gearbox component failure based on the size of the debris particles in the lubricant. ### Claim 7 (depends on 1) The monitoring system of claim 1, wherein: the monitoring system further includes a communication module and an off-board computer; and the controller is connectable to the communication module and further configured to transmit at least one of the data indicative of the deterioration of the gearbox and the remaining useful life of the gearbox to the off-board computer via the communication module. ### Claim 8 (depends on 7) The monitoring system of claim 7, wherein the controller is further configured to receive off-board data indicative of the deterioration of the gearbox and estimate the remaining useful life of the gearbox based on the off-board data. ### Claim 9 (depends on 1) The monitoring system of claim 1, wherein the data indicative of the deterioration of the gearbox includes at least one of a torque of the gearbox, a speed of the gearbox, a temperature, or a lubricant parameter. ### Claim 10 A method of monitoring a gearbox, comprising: measuring a concentration of debris particles in a lubricant of the gearbox using a first sensor; determining a data indicative of a deterioration of the gearbox using a second sensor; estimating, via a controller, a concentration of debris particles in the lubricant based on the data using a mathematical function stored in a memory of the controller; estimating a remaining useful life of the gearbox, via the controller, based on a difference between the concentration of debris particles measured and the concentration of debris particles estimated to be in the lubricant; and correcting the mathematical function, via the controller, when the difference between the concentration of debris particles measured and the concentration debris particles estimated to be in the lubricant over a period of time is above a first threshold difference and below a second threshold difference. ### Claim 11 (depends on 10) The method of claim 10, further comprising determining the remaining useful life of the gearbox using the mathematical function when the difference between the concentration of debris particles measured and the concentration of debris particles estimated to be in the lubricant over a period of time is below a threshold difference. ### Claim 12 (depends on 10) The method of claim 10, further comprising determining that the lubricant or a gearbox component has been replaced when the concentration of debris particles measured is less than the concentration of debris particles estimated to be in the lubricant by more than a threshold difference over a period of time. ### Claim 13 (depends on 12) The method of claim 12, further comprising: measuring a size of debris particles in the lubricant; and determining when a gearbox component has been replaced based on the size of the debris particles in the lubricant. ### Claim 14 (depends on 10) The method of claim 10, further comprising determining a probability of a gearbox component failure when the concentration of debris particles measured is greater than the concentration of debris particles estimated to be in the lubricant by more than a threshold difference over a period of time. ### Claim 15 (depends on 14) The method of claim 14, further comprising: determining a size of debris particles in the lubricant; and determining the probability of a gearbox component failure based on the size of the debris particles in the lubricant. ### Claim 16 (depends on 10) The method of claim 10, further including determining the data indicative of the deterioration of the gearbox includes determining at least one of a torque of the gearbox, a speed of the gearbox, a temperature, and or a lubricant parameter. ### Claim 17 (depends on 10) The method of claim 10, wherein: the gearbox forms a portion of a drive system for a mobile machine; and the method further includes transmitting at least one of the data indicative of the deterioration of the gearbox and the remaining useful life of the gearbox off-board the machine. ### Claim 18 A mobile machine, comprising: a frame; a power source mounted to the frame; a traction device mounted to the frame; a gearbox drivingly connected between the power source and the traction device, wherein the gearbox contains a lubricant; a first sensor configured to measure a concentration of debris particles in the lubricant; a second sensor configured to generate data indicative of a deterioration of the gearbox; and a controller in communication with the first and second sensors, the controller being configured to: estimate a concentration of debris particles in the lubricant based on the data from the second sensor using a mathematical function; estimate a remaining useful life of the gearbox using the mathematical function when a difference between the concentration of the debris particles measured by the first sensor and the concentration of debris particles estimated to be in the lubricant over a period of time is below a first threshold difference; and correct the mathematical function when the difference between the concentration of debris particles measured by the first sensor and the concentration of debris particles estimated to be in the lubricant over the period of time is above the first threshold difference and below a second threshold difference.