A high-temperature and high-speed gear disc speed measuring device and method

Abstract

The present invention discloses a high-temperature and high-speed gear disc speed measuring device and method, the device comprises a laser beam unit, a constant temperature light cylinder, a mounting frame, an adjustable telescopic platform, and a multi-channel speed measuring module; the laser beam unit comprises a separated laser transmitter and a laser receiver, the laser transmitter and the laser receiver of the laser beam unit are respectively sealed in two constant temperature light cylinders; the two constant temperature light cylinders are respectively fixed at the upper and lower ends of the mounting frame, the adjustable telescopic platform comprises a slide rail and a vertical pole, the mounting frame is fixed on the vertical pole of the adjustable telescopic platform, the vertical pole can slide along the slide rail to the side of the gear disc to be measured, so that the laser emitted by the laser beam unit passes through the tooth gap of the gear disc to be measured; the multi-channel speed measuring module is used to measure the frequency of the electrical pulse signal output by multiple groups of laser beam units, and average the multiple groups of measurement results to obtain the stable speed of the gear disc. The present invention can quickly and accurately measure the stable speed of the high-temperature and high-speed gear disc.

Description

Technical Field

[0001] The invention belongs to the technical field of rotation speed measurement and testing equipment, and particularly relates to a high-temperature and high-speed gear disc speed measuring device and method. Background Art

[0002] High-speed gears are widely used in various mechanical transmission systems in the fields of automobiles, aerospace, rail transportation, engineering machinery, ships, etc. to achieve mechanical transmission. As a high-speed gear, the rotational motion characteristics and dynamic characteristics are extremely critical mechanical characteristics. The rotational motion characteristics are mainly characterized by the gear speed parameters, and the dynamic characteristics are described by parameters such as gear deformation and vibration. At the same time, the harsh high-temperature working environment that is common with high-speed rotation is also an environmental factor that affects the mechanical characteristics of the gear and needs to be considered.

[0003] The speed measurement method of high-temperature and high-speed toothed discs is currently mainly to sense and output pulse signals corresponding to the rotation speed and number of teeth of the toothed disc through magnetoelectric speed sensors (including variable reluctance, eddy current, and Hall), and to measure the speed through a counting instrument. This speed measurement method requires that the toothed disc must be made of magnetic material or magnetic conductive material. During measurement, the sensor is fixedly installed at a distance of about 0.5mm to 3mm from the top circle of the tooth, and the rotation frequency can be measured up to 20kHz. However, when the toothed disc is accompanied by high-speed rotation and produces a high-temperature environment, the magnetic components in the toothed disc material and the measuring sensor are affected by the high temperature (especially exceeding 200°C), resulting in a certain degree of reversible or even irreversible decrease in magnetic properties, directly reducing the signal-to-noise ratio of the measured output signal, and reducing the measurement accuracy and reliability; and because the measurement distance of the magnetoelectric speed sensor is extremely short, the deformation of the toothed disc at different temperatures is different, and there is a risk of collision, damage, and accidents. Therefore, a speed measurement device and method that can measure the rotation speed of the toothed disc in a high-temperature environment and does not require the material of the toothed disc to be measured is needed. Summary of the invention

[0004] The purpose of the present invention is to provide a high-temperature and high-speed gear disc speed measuring device and method, which can quickly and accurately measure the stable speed of the high-temperature and high-speed gear disc.

[0005] One aspect of the present invention provides a high-temperature and high-speed gear disc speed measuring device, comprising a laser beam unit, a constant-temperature light tube, a mounting frame, an adjustable telescopic platform, and a multi-channel speed measuring module;

[0006] The laser beam unit includes a separate laser transmitter and a laser receiver, the laser transmitter is used to transmit laser light, and the laser receiver is used to receive laser light. The laser transmitter and the laser receiver of the laser beam unit are respectively sealed in two constant temperature light cylinders, and the constant temperature light cylinders are used to protect the laser beam unit to work stably in a high temperature environment;

[0007] Two constant temperature light cylinders are respectively fixed at the upper and lower ends of the mounting frame, the adjustable telescopic platform includes a slide rail and a vertical rod, the mounting frame is fixed on the vertical rod of the adjustable telescopic platform, and the vertical rod can slide along the slide rail to the side of the gear disc to be measured, so that the laser emitted by the laser irradiation unit passes through the tooth gap of the gear disc to be measured;

[0008] The multi-channel speed measurement module is used to measure the frequency of multiple groups of electrical pulse signals output by the laser irradiation units, and average the multiple groups of measurement results to obtain the stable speed of the gear disc.

[0009] Preferably, the constant temperature optical cylinder comprises a positioning adjustment ring, the laser beam unit is fixedly sealed in the constant temperature optical cylinder through the positioning adjustment ring, and the positioning adjustment ring is fixed to the inner wall of the constant temperature optical cylinder through positioning pins, so as to adjust the optical axis of the laser beam unit.

[0010] Preferably, the upper end surface of the constant temperature light cylinder is sealed with an incident lens, and the lower end surface is sealed with a focusing lens. When the constant temperature light cylinder has a built-in laser transmitter, the laser is emitted through the focusing lens. When the constant temperature light cylinder has a built-in laser receiver, the incident laser is emitted into the laser receiver through the incident lens.

[0011] Preferably, two groups of cooling components are symmetrically distributed on the inner wall of the constant temperature light cylinder for adjusting the internal temperature of the constant temperature light cylinder. The outer wall of the constant temperature light cylinder is wrapped with a heat insulation component, and the heat insulation components are respectively aerogel and high temperature mesh from inside to outside.

[0012] Preferably, the multi-channel speed measurement module is also used to obtain the rotation speed change trend by measuring the time interval of the pulse signals output by two consecutive groups of laser irradiation units, so as to diagnose and identify the rotation state of the measured sprocket.

[0013] Preferably, the laser transmitter is used to emit a small diameter light spot with a diameter not exceeding 1.5 mm, and the measuring distance is not less than 1 m, and the laser receiver adopts an avalanche photodiode.

[0014] Preferably, the mounting frame is mounted on the vertical pole via a slip ring and can rotate around the vertical pole at a certain angle.

[0015] Another aspect of the present invention provides a high-temperature and high-speed gear disc speed measurement method, using the high-temperature and high-speed gear disc speed measurement device to measure the stable speed of the gear disc, comprising:

[0016] Step 1: Fix multiple groups of constant temperature light cylinders with built-in laser beam units on the upper and lower sides of the gear disc to be tested through mounting frames, adjust the laser emitted by each group of laser beam units to pass through the gear disc tooth gap, start the cooling components in the constant temperature light cylinder, and maintain the temperature in the constant temperature light cylinder at a constant room temperature;

[0017] Step 2: Collect the output electrical signals of multiple groups of laser beam units through a multi-channel speed measurement module. When the gear disc to be tested is in a stable rotation state, use the channel speed measurement module to measure the frequency of the electrical pulse signal output by each group of laser beam units, and obtain the stable rotation speed of the gear disc to be tested as follows:

[0018]

[0019] Where n is the stable speed of the gear disc, f i is the frequency of the electrical pulses output by each group of laser irradiation units, and N is the number of groups.

[0020] Preferably, the method further comprises:

[0021] Step 3: Use the channel speed measurement module to measure the time interval between the electrical pulse signal output by the first laser beam unit 1 and the electrical pulse signal output by the second laser beam unit 1. According to the time interval, the speed drift rate is obtained as follows:

[0022]

[0023] Where Δn i is the speed drift rate of the gear wheel over a period of time, t i，1 , t i+1，1 , t i，2 , t i+1，2 It is the time of the electric pulse output by the first and second groups of laser irradiation units when they pass through two adjacent teeth respectively.

[0024] Preferably, when the toothed disc rotates one circle, the speed drift rate sequence {Δn1, Δn2, Δn3, ..., Δn m}, where m is the number of teeth. When the sequence shows a monotonically increasing or decreasing trend, it is diagnosed that the rotation state of the tested gear is unstable; when the sequence shows a sinusoidal change with the same frequency as the rotation speed, it is diagnosed that the gear has dynamic imbalance.

[0025] The high-temperature and high-speed gear disc speed measuring device and method according to the above aspects of the present invention can quickly and accurately measure the stable speed of the high-temperature and high-speed gear disc, and can also identify and diagnose the speed drift of the gear disc's speed change rotation. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings used in the description of the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work:

[0027] Figure 1This is a schematic diagram of the overall structure of a high-temperature and high-speed gear disc speed measuring device according to an embodiment of the present invention;

[0028] Figure 2 The figure is a schematic structural diagram of a constant temperature light cylinder according to an embodiment of the present invention. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] The embodiment of the present invention provides a high-temperature and high-speed gear disc speed measuring device. Figure 1 FIG. 1 is a schematic diagram of the overall structure of a high-temperature and high-speed gear disc speed measuring device according to an embodiment of the present invention. Figure 1 As shown, the high-temperature and high-speed gear disc speed measuring device of the embodiment of the present invention comprises a laser irradiation unit 1, a constant temperature light tube 2, a mounting frame 3, an adjustable telescopic platform 4, and a multi-channel speed measuring module 5. The laser irradiation unit 1, the constant temperature light tube 2, the mounting frame 3, and the gear disc to be measured can be placed in a high-temperature box, and the multi-channel speed measuring module 5 can be connected to a computer.

[0031] The laser beam unit 1 is used to emit and receive laser light and perform photoelectric conversion. The laser beam unit 1 includes a laser emitter and a laser receiver that are separated. The laser emitter can be used to emit a small-diameter spot with a diameter not exceeding 1.5 mm, and its measurement distance is not less than 1 m. The laser receiver uses an avalanche photodiode.

[0032] The laser transmitter and laser receiver of the laser beam unit 1 are sealed in two constant temperature light cylinders 2, respectively, and the wiring passes through the constant temperature light cylinder 2 in an armored form. The constant temperature light cylinder 2 is a sealed light cylinder with a built-in laser transmitter or laser receiver to enable it to work in a high temperature environment. In one embodiment, the length × width × height of the constant temperature light cylinder 2 is 100 mm × 30 mm × 20 mm, and the outer wall thickness of the light cylinder is 5 mm.

[0033] The constant temperature light tube 2 is used to protect the laser beam unit 1 to work stably in a high temperature environment. Figure 2 As shown, the constant temperature light cylinder 2 includes a positioning adjustment ring 21 , a cooling component 23 , a heat insulating component 24 , and a lens 22 .

[0034] The positioning adjustment ring 21 is made of high temperature resistant ceramic material and is fixed between the inner walls of the constant temperature optical cylinder 2 by titanium alloy positioning pins, and the positioning pins penetrate the outer wall of the constant temperature optical cylinder 2. The middle of the positioning adjustment ring 21 is used to clamp the laser transmitter and laser receiver in the laser beam unit 1. In order to achieve fine adjustment of the laser optical axis and the receiving end position, after the laser transmitter and the laser receiver are fixed to the positioning adjustment ring 21, by rotating the positioning pins on the outer wall of the constant temperature optical cylinder 2, the center line distance of the positioning adjustment ring 21 can be fine-tuned in a direction perpendicular to the inner wall of the constant temperature optical cylinder 2, and the optical axis adjustment of the laser beam unit 1 can be achieved.

[0035] The shell of the thermostatic light cylinder 2 is a rectangular parallelepiped, and two groups of cooling components 23 are symmetrically distributed on the inner wall, which are used to adjust the internal temperature of the thermostatic light cylinder 2. The cooling component 23 is a semiconductor refrigeration sheet, which can stably adjust the inner wall temperature of the thermostatic light cylinder 2 to a normal temperature state within a temperature range of 100°C to ensure the normal working environment temperature of the laser irradiation unit 1.

[0036] The outer wall of the constant temperature light cylinder 2 is wrapped with a heat-insulating component 24, which is respectively composed of aerogel and high-temperature mesh from the inside to the outside. The high-temperature mesh is wrapped around the outside of the aerogel. The thickness of the aerogel and the high-temperature mesh is 20 mm, which can ensure that the outer wall of the constant temperature light cylinder 2 maintains a temperature of no more than 100°C for at least ten minutes in a high-temperature environment of 300°C.

[0037] The upper and lower end surfaces of the thermostatic light cylinder are respectively sealed with lenses 22 for incident and outgoing lasers. The upper end surface of the thermostatic light cylinder 2 is sealed with the incident lens 22, and the lower end surface is sealed with the focusing lens 22. When the laser transmitter is built in, the emitted laser is emitted through the focusing lens 22 to ensure that the diameter of the outgoing laser spot does not exceed 1.5mm; when the laser receiver is built in, the incident laser is emitted into the receiver surface through the incident lens 22 on the upper end surface.

[0038] The upper and lower ends of the mounting frame 3 are used to fix the constant temperature light cylinder 2. The mounting frame 3 is a long rod with a dovetail groove. The constant temperature light cylinder 2 is coaxially mounted at the upper and lower ends of the mounting frame 3. The distance between the two light cylinders is adjustable.

[0039] The mounting frame 3 is fixed on the adjustable telescopic platform 4. The mounting frame 3 and the adjustable telescopic platform 4 are made of high temperature resistant metal materials. The adjustable telescopic platform 4 includes a slide rail and a vertical pole. The vertical pole can slide forward and backward along the slide rail to the side of the gear disc to be measured, so that the laser emitted by the laser beam unit 1 passes through the tooth gap of the gear disc to be measured. The mounting frame 3 is installed on the vertical pole through a slip ring and can rotate around the vertical pole at a certain angle.

[0040] The multi-channel speed measurement module 5 is used for measuring the required speed and identifying changes. The multi-channel speed measurement module 5 can count the frequency of the electrical pulse signals output by multiple groups of laser beam units 1 and average the multiple groups of measurement results in a short time to achieve faster and more stable extraction of the stable speed of the gear disc. The multi-channel speed measurement module 5 obtains the speed change trend by measuring the time interval of the pulse signals output by two consecutive groups of laser beam units 1, thereby diagnosing and identifying the rotation state of the gear disc being measured.

[0041] The embodiment of the present invention further provides a high-temperature and high-speed gear disc speed measurement method, which uses the high-temperature and high-speed gear disc speed measurement device of the above embodiment to measure the stable speed of the gear disc, including the following steps:

[0042] Step 1: fix multiple groups of constant temperature light cylinders 2 with built-in laser beam units 1 on the upper and lower sides of the gear disc to be tested through the mounting frame 3, and adjust the laser emitted by each group of laser beam units to pass through the gear disc tooth gap and be correctly received, start the cooling component 23 in the constant temperature light cylinder 2, and maintain the temperature in the constant temperature light cylinder 2 at a constant room temperature;

[0043] Step 2: Use the multi-channel speed measurement module 5 to collect the output electrical signals of multiple groups of laser beam units 1. When the gear disc to be tested is in a stable rotation state, use the frequency counting function of the channel speed measurement module 5 to measure the frequency of the electrical pulse signal output by each group of laser beam units 1. The stable rotation speed of the gear disc to be tested satisfies the following relationship:

[0044]

[0045] Where n is the stable speed of the gear disc, f i The output electrical pulse frequency of each group of laser irradiation units, N is the number of groups.

[0046] In one embodiment, the high temperature and high speed gear disc speed measurement method of the embodiment of the present invention further includes:

[0047] Step 3: When measuring the speed drift of the gear to be measured, based on the known starting speed, the electric pulse signal output by a certain group of laser beam units 1 is measured along the rotation direction of the gear with the time interval of the electric pulse signal output by the laser beam units 1 at other installation locations. The speed drift rate and the time interval satisfy the following relationship:

[0048]

[0049] Where Δn i is the speed drift rate of the gear wheel over a period of time, t i，1 , t i+1，1 , t i，2 , t i+1，2 It is the time of the electric pulse output by the first and second groups of laser irradiation units when they pass through two adjacent teeth respectively.

[0050] When the toothed disc rotates one circle, the speed drift rate sequence {Δn1, Δn2, Δn3, ..., Δn m}, where m is the number of teeth. When the sequence shows a monotonically increasing or decreasing trend, it can be diagnosed that the rotation state of the tested gear is unstable; when the sequence shows a sinusoidal change with the same frequency as the rotation speed, it can be diagnosed that the gear has dynamic imbalance.

[0051] In one embodiment, in step 1, two constant temperature light cylinders 2 with built-in laser beam units 1 are respectively fixed to the upper and lower ends of the mounting frame 3, the two constant temperature light cylinders 2 are adjusted to be 350 mm apart, and the optical axis of the laser beam unit 1 is adjusted to obtain a good high-level signal. The mounting frame 3 is fixed on the vertical pole of the adjustable telescopic platform 4, and the vertical pole slides forward and backward along the slide rail of the adjustable telescopic platform 4 to the side of the high-temperature gear disk. Fine-tune so that the laser of the laser beam unit 1 just passes through the tooth gap. Four groups of laser beam units 1 installed on the adjustable telescopic platform 4 are evenly distributed around the gear disk in the same installation manner.

[0052] In step 2, a 60-tooth straight-tooth iron toothed disc with a diameter of 120 mm and a thickness of 8 mm is used to rotate in a temperature environment of 300°C. When the maximum speed reaches 18,000 r / min, the multi-channel speed measurement module 5 is used to simultaneously read the electrical pulse frequencies output by the four groups of laser beam units 1, and the speed is calculated to obtain the stable speed of the toothed disc, and the speed measurement uncertainty can be better than one ten-thousandth.

[0053] In step three, the motor is controlled to increase from 2000r / min to 2002r / min within 1 second. The speed drift rate sequence measured by the multi-channel speed measurement module 5 shows a monotonically decreasing trend. It can be seen that the speed is in a drift state and its drift rate at this time. A magnet with a diameter of 5mm and a thickness of 3mm is attached to the surface of the toothed disc at a position 4 / 5 of the toothed disc radius from the rotating shaft to affect the mass distribution of the toothed disc during rotation to simulate its dynamic unbalanced state. The motor is controlled to have a stable speed of 1000r / min. The speed drift rate sequence measured by the multi-channel speed measurement module 5 shows a periodic change, and the change period is close to the toothed disc speed.

[0054] The high-temperature and high-speed gear disc speed measuring device and method of the above-mentioned embodiment of the present invention has the following beneficial effects:

[0055] 1. The present invention is more suitable for high temperature environment and is not affected by the decrease of magnetic properties at high temperature;

[0056] 2. The present invention does not need to be installed coaxially with the rotating shaft, that is, it can obtain more accurate stable speed results in a short time by arranging multiple groups of laser irradiation units, thereby improving the feedback control efficiency;

[0057] 3. The present invention can obtain information on the speed change process and diagnose different working conditions of the gear disc by positioning and arranging multiple groups of laser beam units.

[0058] To summarize, the high-temperature and high-speed gear disc speed measuring device and method of the above-mentioned embodiment of the present invention aims to solve the problems that the current high-speed rotating gear disc speed measurement method in a high-temperature environment is limited by the gear disc material and the ambient temperature, has low measurement accuracy, is prone to damage, etc. A laser beam speed measurement method is adopted, and a constant temperature device is used to ensure that the speed measuring device can work in a high-temperature environment and is not limited by the rotating gear disc material; fast and accurate stable speed measurement is achieved by averaging multiple groups of speed measurement channels; the speed change trend is obtained by measuring the time interval change trend of two or more groups of speed measurement channels, so as to realize the diagnosis of the rotation state of the high-temperature and high-speed gear disc.

[0059] The above description is only by way of illustration of certain exemplary embodiments of the present invention. It is undoubted that those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A high-temperature and high-speed gear disc speed measuring device, characterized in that: It includes laser beam unit, constant temperature light tube, mounting frame, adjustable telescopic platform and multi-channel speed measurement module; The laser beam unit includes a separate laser transmitter and a laser receiver, the laser transmitter is used to transmit laser light, and the laser receiver is used to receive laser light. The laser transmitter and the laser receiver of the laser beam unit are respectively sealed in two constant temperature light cylinders, and the constant temperature light cylinders are used to protect the laser beam unit to work stably in a high temperature environment; Two constant temperature light cylinders are respectively fixed at the upper and lower ends of the mounting frame, the adjustable telescopic platform includes a slide rail and a vertical rod, the mounting frame is fixed on the vertical rod of the adjustable telescopic platform, and the vertical rod can slide along the slide rail to the side of the gear disc to be measured, so that the laser emitted by the laser irradiation unit passes through the tooth gap of the gear disc to be measured; The multi-channel speed measurement module is used to measure the frequency of multiple groups of electrical pulse signals output by the laser irradiation units, and average the multiple groups of measurement results to obtain the stable speed of the gear disc; The constant temperature optical cylinder includes a positioning adjustment ring, through which the laser beam unit is fixedly sealed in the constant temperature optical cylinder. The positioning adjustment ring is fixed to the inner wall of the constant temperature optical cylinder by positioning pins, and the optical axis of the laser beam unit can be adjusted; The upper end surface of the constant temperature light cylinder is sealed with an incident lens, and the lower end surface is sealed with a focusing lens. When the constant temperature light cylinder is equipped with a built-in laser transmitter, the laser is emitted through the focusing lens. When the constant temperature light cylinder is equipped with a built-in laser receiver, the incident laser is emitted into the laser receiver through the incident lens. Two groups of cooling components are symmetrically distributed on the inner wall of the constant temperature light cylinder for adjusting the internal temperature of the constant temperature light cylinder. The outer wall of the constant temperature light cylinder is wrapped with a heat insulation component, which is respectively aerogel and high temperature mesh from inside to outside.

2. The high-temperature and high-speed gear disc speed measuring device according to claim 1, characterized in that: The multi-channel speed measurement module is also used to obtain the rotation speed change trend by measuring the time interval of the pulse signals output by two consecutive groups of laser irradiation units, so as to diagnose and identify the rotation state of the measured gear disk.

3. The high temperature and high speed gear disc speed measuring device according to claim 1 or 2, characterized in that: The laser transmitter is used to emit a small diameter light spot with a diameter not exceeding 1.5 mm, and the measuring distance is not less than 1 m, and the laser receiver adopts an avalanche photodiode.

4. The high temperature and high speed gear disc speed measuring device according to claim 1 or 2, characterized in that: The mounting frame is mounted on the vertical pole via a slip ring and can rotate around the vertical pole at a certain angle.

5. A high-temperature and high-speed gear disc speed measurement method, using the high-temperature and high-speed gear disc speed measurement device according to any one of claims 1 to 4 to measure the stable gear disc speed, comprising: Step 1: Fix multiple groups of constant temperature light cylinders with built-in laser beam units on the upper and lower sides of the gear disc to be tested through mounting frames, adjust the laser emitted by each group of laser beam units to pass through the gear disc tooth gap, start the cooling components in the constant temperature light cylinder, and maintain the temperature in the constant temperature light cylinder at a constant room temperature; Step 2: Collect the output electrical signals of multiple groups of laser beam units through a multi-channel speed measurement module. When the gear disc to be tested is in a stable rotation state, use the channel speed measurement module to measure the frequency of the electrical pulse signal output by each group of laser beam units, and obtain the stable rotation speed of the gear disc to be tested as follows: Where n is the stable speed of the gear disc, f i is the frequency of the electrical pulses output by each group of laser irradiation units, and N is the number of groups.

6. The high temperature and high speed gear disc speed measurement method according to claim 5, characterized in that: Also includes: Step 3: Use the channel speed measurement module to measure the time interval between the electrical pulse signal output by the first group of laser beam units and the electrical pulse signal output by the second group of laser beam units. According to the time interval, the speed drift rate is obtained as follows: Where Δn i is the speed drift rate of the gear wheel over a period of time, t i,1 ,t i+1,1 ,t i,2 ,t i+1,2 It is the time of the electric pulse output by the first and second groups of laser irradiation units when they pass through two adjacent teeth respectively.

7. The high temperature and high speed gear disc speed measurement method according to claim 6, characterized in that: When the toothed disc rotates one circle, the speed drift rate sequence {Δn1, Δn2, Δn3, …, Δn m }, where m is the number of teeth. When the sequence shows a monotonically increasing or decreasing trend, it is diagnosed that the rotation state of the tested gear is unstable; when the sequence shows a sinusoidal change with the same frequency as the rotation speed, it is diagnosed that the gear has dynamic imbalance.

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