Gear fault detection experiment table based on infrared temperature measurement
By designing a gear fault detection test bench based on infrared temperature measurement, using a constant temperature environment and a high-precision infrared temperature measurement sensor array, the problem of the infrared method being susceptible to the environment in the existing technology is solved, and high-precision and low-cost gear fault detection is achieved.
Patent Information
- Application Number
- CN202510369528.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-27
- Publication Date
- 2025-06-10
AI Technical Summary
In the prior art, the infrared method of gear fault detection is susceptible to environmental impact, and the detection equipment is costly, making it difficult to realize online fault detection.
A gear fault detection laboratory table based on infrared temperature measurement was designed, and a thermal insulation cover was used to ensure a constant temperature environment. Three high-precision infrared temperature measurement sensors were used to form an equilateral triangle array to reduce environmental interference, and the radial force and infrared radiation intensity of the gear were measured through transmission and pressure sensors.
It realizes high-precision gear fault detection in a constant temperature environment, reduces environmental interference, improves detection accuracy and reliability, and reduces equipment costs.
Smart Images
Figure CN120121291A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of gear fault diagnosis, and particularly relates to a gear fault detection test bench based on infrared temperature measurement. Background Art
[0002] In today's mechanical equipment production, gear transmission is one of the most commonly used transmission methods. Gear failure is one of the important factors affecting the production activities of equipment. In modern industrial production, it is extremely common for various losses to occur due to the failure of gears not being detected in time, and the resulting economic losses are extremely prominent. Therefore, on-line monitoring and fault diagnosis of gear sets can not only improve the safety and reliability of transmission equipment, but also effectively reduce maintenance costs, avoid sudden accidents, and reduce economic losses. At present, the monitoring and diagnosis technologies for gear transmission mainly include methods such as vibration analysis, acoustic detection, temperature monitoring, and oil analysis.
[0003] The infrared method is widely used in gear fault detection. As a non-contact temperature measurement method, its principle is to capture the infrared radiation signal generated on the gear surface due to friction, wear, or local overheating, so as to judge the operating state of the gear. Compared with traditional methods such as vibration analysis and noise monitoring, the infrared method has the advantages of fast response speed and being free from mechanical vibration interference, and is particularly suitable for gear fault detection under high-speed and heavy-load working conditions.
[0004] The gear fault detection device based on the infrared method mainly uses a fixed infrared sensor or a portable thermal imager. The infrared method can achieve non-contact measurement and will not affect the main part of the gear operation. It can play a role in timely warning in the early stage of gear operation, reduce losses, and increase the safety of the equipment. Most of the existing technologies in the infrared method are aimed at the algorithm processing of the collected infrared signals. When collecting signals, a single infrared temperature measurement sensor is mostly used. Therefore, the interference of the ambient temperature in the signal collection link is still the main problem to be solved. There is an urgent need for a new type of gear fault detection device that can realize on-line fault detection function using the infrared method to improve the detection accuracy and efficiency. Summary of the Invention
[0005] The purpose of the present invention is to provide a gear fault detection test bench based on infrared temperature measurement to solve the problems of being easily affected by the environment and high cost of detection equipment in the infrared method of gear faults in the prior art.
[0006] The present invention achieves the above object through the following technical solutions: A gear fault detection test bench based on infrared temperature measurement, including a main truss of the test bench, a thermal insulation cover, a device fixing frame, a transmission device, a gear picking and placing device, a detection device, and a PLC wire box. There are also the following devices arranged in sequence from left to right on the main truss of the test bench: The transmission device provides power for the test gear sleeved on the motor that drives the test gear to rotate and move from left to right to impact the gear to be tested. It is provided with a bottom cylinder head; a fixing nut; a screw rod; a cylinder bottom cover; a hydraulic rod; a pressure sensor; a cylinder body; The gear picking and placing device can be used to replace damaged gears and adjust the test gear and the gear to be tested to the same horizontal plane. It is provided with a placing table; a support; a spare gear; a support frame; a support block; a claw; The detection device is used to measure the infrared radiation intensity when the gears collide, thereby realizing the fault detection of the gears. It is provided with an infrared temperature measurement sensor positioning screw; an infrared temperature measurement sensor; an experimental gear gear shaft limiting device positioning screw; an experimental gear gear shaft limiting device; an experimental gear; an experimental gear motor shaft; a coupling; a motor that drives the experimental gear to rotate; a slider; a sliding table; a gear to be tested gear shaft limiting device positioning screw; a gear to be tested gear shaft limiting device; a gear to be tested limiting sleeve; a gear to be tested motor shaft; a gear to be tested; a motor that drives the gear to be tested to rotate; a positioning screw of the motor that drives the gear to be tested to rotate.
[0007] As a further optimized solution of the present invention, the detection device performs detection under the thermal insulation cover to ensure a constant temperature environment and ensure the accuracy of subsequent detection.
[0008] As a further optimized solution of the present invention, the transmission device is arranged at the upper left end of the device fixing frame, and mainly connects and pushes the pressure sensor through a hydraulic rod and measures the thrust Furthermore, the radial force between the two gears is calculated .
[0009] As a further optimized solution of the present invention, the inner surfaces of the experimental gear gear shaft limiting device and the gear to be tested gear shaft limiting device are approximately tangent to the motor shafts that drive their respective gears to rotate, and the inner surfaces are provided with circular small planes similar to deceleration collar rings, which can further reduce the impact, play a role in protecting the gears, and improve the service life.
[0010] As a further optimized solution of the present invention, the gear picking and placing device is located at the rear end of the detection device. On its left side is a placing table on which a spare gear is placed, which can be used to replace damaged gears and adjust the test gear and the gear to be tested to the same horizontal plane.
[0011] As a further optimized solution of the present invention, the infrared temperature measurement sensor is a single high-precision non-contact infrared temperature measurement sensor, with a quantity of 3, arranged in an equilateral triangle array on the main truss of the test bench and facing the position where the gears collide, and the sampling frequency 。
[0012] As a further optimized solution of the present invention, the PLC wire box is located at the lower left end of the device fixing frame.
[0013] A method for detecting gear faults using the above-mentioned detection test bench includes the following steps: S1: Adjust the test gear and the gear to be tested to be on the same horizontal plane through the cooperation of the support block and the claw in the gear picking and placing device, move the motor driving the test gear to the leftmost end of the cableway, and supply power to the PLC wire box to make the motor rotate, and externally connect the pressure sensor and the infrared temperature sensor to the computer in sequence; S2: Start the motor to work. The motor drives the test gear and the gear to be tested to rotate. The test gear is pushed to impact the gear to be tested through the transmission device, and the data measured by the pressure sensor and the infrared temperature sensor are output through the computer; S3: Analyze and process the data. The data obtained by the three infrared temperature sensors are averaged to exclude interference data, observe the temperature of the gear set under the corresponding radial force, and compare it with the theoretical threshold to achieve the purpose of fault diagnosis.
[0014] As a further optimized solution of the present invention, the thrust measured by the pressure sensor in step S2 is denoted as , and the infrared radiation power measured by the infrared temperature sensor is , so the following processing will be performed on the data: S2-1: The thrust measured by the pressure sensor, then the radial force between the two gears is ; where is the gear pressure angle; S2-2: The infrared radiation power can be measured by the infrared temperature sensor, then the self-radiation temperature of the gear is ; where is the emissivity of the material; is the Stefan-Boltzmann constant; is the area of the radiation measurement region; S2-3: At the same time, the actual temperature also includes the influence of environmental radiation, and environmental temperature compensation should be added, then the true temperature is , and then {T}_{true}=\sqrt[{4}] {{T}^{4}_{obj}+{T}^{4}_{env}} ; S2-4: At the same time, through theoretical derivation, the temperature rise after collision and the radial force between the two gears have the relationship of ; wherein, is the stiffness; is the gear mass; is the specific heat capacity; S2-5: Integrate the obtained data, observe the temperature of the gear set under the corresponding radial force, and compare it with the theoretical threshold to achieve the purpose of fault diagnosis.
[0015] The beneficial effects of the present invention are as follows: (1) In the present invention, the experimental process is carried out in the heat preservation cover located on the main truss of the experimental bench to ensure a constant temperature in the experimental environment, which guarantees the preconditions for the data stability and accuracy of infrared temperature measurement; (2) In the present invention, limit devices are provided for the motor shafts driving the experimental gear and the gear to be measured, which maximally protects the motor and the gear, improves their service life, and enhances the safety of detection; (3) The present invention uses the infrared method for gear fault detection, which can achieve early fault identification. Compared with the traditional vibration method, it can detect problems at the initial stage of heat accumulation, give early warnings, and greatly increase the service cycle of the equipment; (4) The present invention can achieve non-contact measurement. At the same time, the directions of the infrared temperature sensors in the present invention are all towards the gear meshing position. Compared with the traditional infrared temperature sensors, it avoids the interference of heat sources in other different transmission paths in the equipment. At the same time, the present invention is provided with 3 infrared temperature sensors, and the 3 infrared temperature sensors are arranged in an equilateral triangle array, which increases the reliability of the measured data and maximally reduces the data limitation at the cost of reducing costs, which is beneficial to improving the accuracy and reliability of fault diagnosis. Description of the Drawings
[0016] Figure 1 is the structural schematic diagram of the gear fault detection experimental bench provided in the present invention.
[0017] Figure 2 is the structural schematic diagram of the transmission device in the present invention.
[0018] Figure 3 is the structural schematic diagram of the gear picking and placing device in the present invention.
[0019] Figure 4 is the structural schematic diagram of the detection device in the present invention.
[0020] In the figure: 1 - Main truss of the test bench; 2 - Thermal insulation cover; 3 - Device fixing bracket; 4 - Transmission device; 41 - Bottom cylinder head; 42 - Fixing nut; 43 - Screw rod; 44 - Bottom cylinder cover; 45 - Hydraulic rod; 46 - Pressure sensor; 47 - Cylinder body; 5 - Gear picking and placing device; 51 - Placing table; 52 - Support; 53 - Spare gear; 54 - Support frame; 55 - Support block; 56 - Claw; 6 - Detection device; 61 - Positioning screw of infrared temperature measurement sensor; 62 - Infrared temperature measurement sensor; 63 - Positioning screw of experimental gear gear shaft limiting device; 64 - Experimental gear gear shaft limiting device; 65 - Experimental gear; 66 - Experimental gear motor shaft; 67 - Coupling; 68 - Motor for driving the experimental gear to rotate; 69 - Slide block; 610 - Slide table; 611 - Positioning screw of the gear shaft limiting device of the gear to be tested; 612 - Gear shaft limiting device of the gear to be tested; 613 - Limiting sleeve of the gear to be tested; 614 - Motor shaft of the gear to be tested; 615 - Gear to be tested; 616 - Motor for driving the gear to be tested to rotate; 617 - Positioning screw of the motor for driving the gear to be tested to rotate; 7 - PLC wire box. Detailed implementation manners
[0021] In order to enable those skilled in the art of this technology to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. It is necessary to point out here that the following specific implementation manners are only used to further illustrate the present application and should not be construed as limiting the protection scope of the present application. All other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.
[0022] As Figures 1-4 shown, the present invention provides a gear fault detection test bench based on infrared temperature measurement, including a main truss 1 of the test bench, a thermal insulation cover 2, a device fixing bracket 3, a transmission device 4, a gear picking and placing device 5, a detection device 6, and a PLC wire box 7. There are also the following devices arranged in sequence from left to right on the main truss 1 of the test bench: The transmission device 4 provides power for the experimental gear 65 sleeved on the motor 68 for driving the experimental gear to rotate to move from left to right to impact the gear 613 to be tested, and it is provided with a bottom cylinder head 41; a fixing nut 42; a screw rod 43; a bottom cylinder cover 44; a hydraulic rod 45; a pressure sensor 46; a cylinder body 47.
[0023] The gear picking and placing device 5 can be used to replace damaged gears and adjust the experimental gear 65 and the gear 612 to be tested to the same horizontal plane. It is provided with a placing table 51; a support 52; a spare gear 53; a support frame 54; a support block 55; a claw 56.
[0024] The detection device 6 is used to measure the infrared radiation intensity when the gears collide, so as to realize the fault detection of the gears. It is provided with an infrared temperature sensor positioning screw 61; an infrared temperature sensor 62; an experimental gear gear shaft limiting device positioning screw 63; an experimental gear gear shaft limiting device 64; an experimental gear 65; an experimental gear motor shaft 66; a coupling 67; a motor 68 that drives the experimental gear to rotate; a slider 69; a slide table 610; a test gear gear shaft limiting device positioning screw 611; a test gear gear shaft limiting device 612; a test gear limiting sleeve 613; a test gear motor shaft 614; a test gear 615; a motor 616 that drives the test gear to rotate; a positioning screw 617 of the motor that drives the test gear to rotate.
[0025] In the present invention, the infrared radiation signal emitted at the gear meshing point will be received by the infrared temperature sensor 62 of the detection device 6.
[0026] In the present invention, when the detection device 6 is working normally, the infrared radiation signals emitted within the gear set can be correctly collected by the infrared temperature sensor 62, and the directions towards which the three infrared temperature sensors are oriented are all at the gear meshing position, and they are arranged in an equilateral triangle array, thereby achieving the effect of excluding other interfering heat sources.
[0027] See Figure 2 , specifically, the bottom cylinder head 41 and the left fixing nut 42 are tightly connected by a screw rod 43, so that it is fixed at the upper left side of the device fixing frame 3. The cylinder bottom cover 44 and the right fixing nut 42 are tightly connected by a screw rod 43, and by using the principle of converting hydraulic energy into linear kinetic energy, compressed air is used to push the hydraulic rod 45 and then push the pressure sensor 46, thereby completing the function of giving the power to impact the test gear 615 with the experimental gear 65, and at the same time, the thrust can be measured by the pressure sensor 46. , and then the radial force can be obtained through calculation. .
[0028] See Figure 3 , specifically, the placement table 51 is located at the bottom end of the device fixing frame 3, and a support 52 is provided above it, which serves to prevent the spare gear 53 from contacting the placement table 51, reducing the wear of the spare gear 53, and at the same time facilitating the grasping and replacement. The support frame 54 is tightly connected to the upper end of the device fixing frame 3, and a support block 55 is sleeved at its lower end. The support block 55 can move up and down within a limited range inside the support frame 54. At the same time, a claw 56 is sleeved at the bottom end of the support block 55. The claw 56 can rotate on the horizontal plane and perform grasping. The cooperation between the claw 56 and the support block 55 can complete the grasping and replacement of the damaged gear, and make the experimental gear 65 and the test gear 615 in the same horizontal plane.
[0029] See Figure 1 、Figure 4 , specifically, the sliding table 610 is tightly connected to the upper end of the device fixing frame 3. The slider 69 below it is tightly connected to the motor 68 that drives the experimental gear to rotate. The slider 69 can slide in the sliding table 610 and also serves as an acceleration channel for the experimental gear 65 to impact the gear under test 615. An experimental gear 65 is sleeved on the experimental gear motor shaft 66, and a coupling 67 is sleeved above the experimental gear 65, which can play a certain buffering and vibration damping effect. At the same time, the experimental gear gear shaft limiting device 64 is tightly connected to the experimental table 1 through the positioning screw 63 of the experimental gear gear shaft limiting device. At the same time, when the experimental gear gear shaft limiting device 64 meshes with the two gears, the experimental gear motor shaft 66 is approximately tangent, playing a role in buffering, vibration damping, and protecting the gears. The motor 616 that drives the gear under test to rotate is tightly connected to the main truss 1 of the experimental table through the positioning screw 617 of the motor that drives the gear under test to rotate. A gear under test 615 is sleeved on the gear under test motor shaft 614, and a gear under test limiting sleeve 613 is provided at the end of the gear under test motor shaft 614, playing a role in preventing the gear from popping out after collision. The gear under test gear shaft limiting device 612 is tightly connected to the upper end of the device fixing frame 3 through the positioning screw 611 of the gear under test gear shaft limiting device and is approximately tangent to the gear under test gear shaft 614, playing a role in buffering, vibration damping, and protecting the gears. At the same time, three infrared temperature sensors 62 are tightly connected to the main truss 1 of the experimental table by the infrared temperature sensor positioning screw 61, and the orientation directions are all at the gear meshing position, making the measurement results more accurate.
[0030] In the present invention, the infrared temperature sensor 62 is specifically a single high-precision non-contact infrared temperature sensor. The three infrared temperature sensors are arranged in an equilateral triangle array infrared temperature sensor to make the measurement results more accurate. Then, data processing is carried out according to the steps disclosed next to complete gear fault detection.
[0031] A method for gear fault detection using the above detection experimental table includes the following steps: S1: Adjust the experimental gear 65 and the gear under test 615 to be on the same horizontal plane through the cooperation of the support block 55 and the claw 56 in the gear picking and placing device 5, move the motor 68 that drives the experimental gear to rotate to the leftmost end of the cableway, and supply power to the plc wire box 7 to make the motor rotate, and externally connect the pressure sensor 46 and the infrared temperature sensor 62 to the computer in sequence; S2: Start the motor to work. The motor drives the experimental gear 65 and the gear under test 615 to rotate. The experimental gear 65 is pushed to impact the gear under test 615 through the transmission device 4, and the data measured by the pressure sensor 46 and the infrared temperature sensor 62 are output through the computer; S3: Analyze and process its data. The data obtained by these three infrared temperature sensors 62 are averaged to exclude interfering data, observe the temperature of the gear set under the corresponding radial force, and compare it with the theoretical threshold to achieve the purpose of fault diagnosis.
[0032] Specifically, in step S2, the thrust measured by the pressure sensor 46 is denoted as , and the infrared radiation power measured by the infrared temperature sensor 62 is . Therefore, the following processing will be performed on the data: S2-1: If the thrust measured by the pressure sensor 46, then the radial force between the two gears is ; where is the gear pressure angle; S2-2: If the infrared radiation power can be measured by the infrared temperature sensor 62, then the self-radiation temperature of the gear is ; where is the emissivity of the material; is the Stefan-Boltzmann constant; is the area of the radiation measurement region; S2-3: At the same time, the actual temperature also includes the influence of environmental radiation, and environmental temperature compensation should be added. Then the true temperature is , and further {T}_{true}=\sqrt[{4}] {{T}^{4}_{obj}+{T}^{4}_{env}} ; S2-4: At the same time, through theoretical derivation, the temperature rise after collision and the radial force between the two gears have the following relationship ; where is the stiffness; is the mass of the gear; is the specific heat capacity; S2-5: Integrate the obtained data, observe the temperature of the gear set under the corresponding radial force, and compare it with the theoretical threshold to achieve the purpose of fault diagnosis.
[0033] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention. The description is relatively detailed and specific, but it cannot be understood as a limitation to the scope of the patent of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and equivalent replacements can still be made, and they should all be covered by the protection scope of the claims of the present invention.
Claims
1. A gear fault detection test bench based on infrared temperature measurement, comprising a test bench main truss (1), a heat preservation cover (2), a device fixing frame (3), a transmission device (4), a gear picking and placing device (5), a detection device (6), and a PLC wire box (7), characterized in that: The test bench also includes the following devices arranged on the main truss (1) of the test bench in order from left to right: a transmission device (4) for providing power for the test gear (65) mounted on the motor (67) for driving the test gear to move from left to right to collide with the gear to be tested (612), which is provided with a bottom cylinder cover (41); a fixing nut (42); a screw rod (43); a cylinder bottom cover (44); a hydraulic rod (45); a pressure sensor (46); a cylinder body (47); a gear picking and placing device (5) for replacing a damaged gear and adjusting the test gear (65) and the gear to be tested (612) to the same horizontal plane, which is provided with a placing table (51); a support (52); a spare gear (53); a support frame (54); a support block (55); a claw (56); a detection device (6) for detecting the gear collision. The infrared radiation intensity during collision is measured, thereby realizing gear fault detection. The device is provided with an infrared temperature sensor positioning screw (61); an infrared temperature sensor (62); a positioning screw (63) of a gear shaft limiting device of an experimental gear; a gear shaft limiting device (64) of an experimental gear; an experimental gear (65); a motor shaft (66) of an experimental gear; a coupling (67); a motor (68) for driving the experimental gear to rotate; a slider (69); a slide table (610); a positioning screw (611) of a gear shaft limiting device of a gear to be tested; a gear shaft limiting device (612) of a gear to be tested; a positioning sleeve (613) of a gear to be tested; a motor shaft (614) of a gear to be tested; a gear to be tested (615); a motor (616) for driving the gear to be tested; and a positioning screw (617) of a motor for driving the gear to be tested to rotate.
2. According to claim 1, a gear fault detection test bench based on infrared temperature measurement is characterized in that: The detection device (6) performs detection under the heat-insulating cover (2), thereby ensuring a constant temperature environment and the accuracy of subsequent detection.
3. The gear fault detection test bench based on infrared temperature measurement according to claim 1 is characterized in that: The transmission device (4) is arranged on the left side of the upper end of the device fixing frame (3), and is mainly connected and pushed by the pressure sensor (46) through the hydraulic rod (45), and the thrust is measured. Then the radial force between the two gears is calculated .
4. The gear fault detection test bench based on infrared temperature measurement according to claim 1 is characterized in that: The inner surfaces of the experimental gear shaft limiting device (64) and the gear shaft limiting device (612) of the gear to be tested are approximately tangent to the motor shaft that drives the respective gears to rotate, and the inner surfaces are provided with a circular small plane similar to a deceleration collar, which can further reduce the impact, protect the gears, and increase the service life.
5. The gear fault detection test bench based on infrared temperature measurement according to claim 1 is characterized in that: The gear picking and placing device (5) is located at the rear end of the detection device (6), and the left side thereof is a placement table (51) on which a spare gear (5) is placed, which can be used to replace a damaged gear and adjust the test gear (65) and the gear to be tested (615) to the same horizontal plane.
6. The gear fault detection test bench based on infrared temperature measurement according to claim 1 is characterized by: The infrared temperature measurement sensor (62) is a single high-precision non-contact infrared temperature measurement sensor, the number of which is 3 and arranged in an equilateral triangle array, arranged on the main truss of the experimental platform and oriented toward the position where the gear collides, and the sampling frequency is .
7. The gear fault detection test bench based on infrared temperature measurement according to claim 1 is characterized by: The PLC wire box (7) is located on the left side of the lower end of the device fixing frame (3).
8. A method for gear fault detection using the detection test bench according to any one of claims 1 to 7, characterized in that: The steps include: S1: The support block (55) and the claw (56) in the gear pick-up and placement device (5) are used to adjust the test gear (65) and the gear to be tested (615) to be located in the same horizontal plane, and the motor (68) that drives the test gear to rotate is moved to the leftmost end of the cableway, and the PLC wire box (7) is powered to make the motor rotate, and the pressure sensor (46) and the infrared temperature sensor (62) are connected to the computer in sequence; S2: starting the motor to drive the test gear (65) and the gear to be tested (615) to rotate, pushing the test gear (65) to collide with the gear to be tested (615) through the transmission device (4), and outputting the data measured by the pressure sensor (46) and the infrared temperature sensor (62) through the computer; S3: Analyze and process the data, take the average value of the data obtained by the three infrared temperature sensors (62) to eliminate interference data, observe the temperature of the gear set under the corresponding radial force, and compare it with the theoretical threshold value to achieve the purpose of fault diagnosis.
9. A gear fault detection method according to claim 8, characterized in that The thrust measured by the pressure sensor (46) in step S2 is recorded as , the infrared radiation power measured by the infrared temperature sensor (62) is , so the data will be processed as follows: S2-1: Thrust measured by pressure sensor (46) , then there is a radial force between the two gears ;in, is the gear pressure angle; S2-2: The infrared radiation power can be measured by the infrared temperature sensor (62) , then the gear's own radiation temperature is ;in, is the emissivity of the material; is the Stefan-Boltzmann constant; is the area of radiation measurement; S2-3: At the same time, the actual temperature also includes the influence of environmental radiation, and the ambient temperature compensation should be added to obtain the real temperature. , and then get ; S2-4: At the same time, the temperature rise after collision can be obtained through theoretical deduction Radial force between two gears The relationship is ;in, is stiffness; is the gear mass; is the specific heat capacity; S2-5: Integrate the obtained data, observe the temperature of the gear set under the corresponding radial force, and compare it with the theoretical threshold to achieve the purpose of fault diagnosis.