A fan main shaft bearing monitoring system based on grating type bidirectional displacement sensor

Abstract

The present invention provides a grating type bidirectional displacement sensor, comprising a PCB assembly and two groups of sensing detection units, a double-track grating ruler is fixed on a sliding base of the sensing detection unit, the PCB assembly comprises a photoelectric conversion chip and a data processing chip, the photoelectric conversion chip and the data processing chip are connected, an LED light-emitting tube is embedded on the photoelectric conversion chip, when the sliding base slides, the photoelectric conversion chip captures the change of the double-track grating ruler signal, the data processing chip outputs the displacement value, and the bidirectional displacement can be simultaneously monitored with high monitoring accuracy; a fan main shaft bearing monitoring system based on the grating type bidirectional displacement sensor is also provided, which simultaneously monitors the radial runout displacement of the bearing outer ring relative to the bearing inner ring and the tangential relative displacement between the bearing outer ring and the fixed base frame, has a simple structure and low cost.

Description

Technical Field

[0001] The present invention relates to the technical field of fan main shaft bearing monitoring, and in particular to a grating type bidirectional displacement sensor and a fan main shaft bearing monitoring system based on the grating type bidirectional displacement sensor. Background Art

[0002] The main shaft bearing of a wind turbine is an important component that supports the rotation of the wind turbine to generate electricity. Once a problem occurs in the main shaft bearing, it will directly affect the normal operation of the wind turbine and may even result in the serious consequence of the entire generator rotor falling off. Therefore, it is particularly necessary to monitor the health status of the main shaft bearing. At present, most of the market adopts the monitoring of the temperature change of the main shaft bearing to determine the health status of the main shaft bearing. For example, patent CN201911355993.3 discloses a method for judging the health status of the main shaft bearing of a wind turbine set based on the temperature change trend. The temperature change trend of the two main shaft bearings within a specified time is judged. If the temperature change trends of the two main shaft bearings are inconsistent within this period of time, the result of this period of time is recorded as 1, indicating that the main shaft bearing may be abnormal. If the temperature change trends of the two main shaft bearings are consistent, the change trend of this period of time is recorded as 0, indicating that there is no abnormality in the main shaft bearing. Through continuous monitoring of the temperature change trends of the two main shaft bearings, when the main shaft bearing has multiple inconsistent temperature change trends within a long period of time, it is determined that the health status of the main shaft bearing is abnormal, and the shutdown inspection should be arranged and the maintenance cycle of the main shaft bearing should be shortened to extend the service life of the main shaft bearing. The invention can accurately judge the health status of the main shaft bearing, discover the early failure of the main shaft bearing, and help extend the service life of the main shaft bearing. However, this method is greatly affected by the environment and cannot perform convenient and effective intuitive monitoring of the actual working status of the main shaft bearing.

[0003] More sensors can also be used to monitor the operation of the wind turbine, and statistical analysis can be used to predict the health status of the main shaft bearing. For example, patent CN201910788602.0 discloses a method for predicting main shaft bearing faults of wind turbines. This method is based on the historical fault maintenance data of the main shaft bearings of the wind turbine, combined with statistical and machine learning methods, with multiple monitoring indicators of the wind turbine as input variables, and the main shaft bearing status as the predicted output variable. The predicted values ​​of the output variables are statistically analyzed, and thresholds are set for fault prediction. This method has high accuracy and stability, and can predict main shaft bearing failures one week in advance and detect early abnormalities as early as possible. However, this method is costly and has low prediction accuracy, and it is impossible to provide effective early warning in the early stages of main shaft bearing problems. Summary of the invention

[0004] In order to solve the above-mentioned deficiencies in the prior art, the present invention provides a grating type bidirectional displacement sensor and a fan main shaft bearing monitoring system based on the grating type bidirectional displacement sensor. The displacement sensor can realize simultaneous monitoring of bidirectional displacement with high monitoring accuracy. The monitoring system can monitor the status of the main shaft bearing in real time and effectively alarm for abnormal status of the main shaft bearing. The system has a simple structure and low cost.

[0005] The technical solution adopted to achieve the above-mentioned purpose of the present invention is:

[0006] A grating type bidirectional displacement sensor, comprising a housing fixedly connected to a measured object, a sensor module and a circuit module located in the housing, the circuit module being connected to the sensor module, the sensor module comprising two groups of sensor detection units and a PCB assembly located between the two groups of sensor detection units, the three being arranged in parallel up and down, the two groups of sensor detection units being perpendicular to each other in space, the PCB assembly being fixed in the housing; the sensor detection unit comprising a sliding base, a guide rod and a double-track grating ruler, wherein the guide rod is fixed in the housing, the inner end of the sliding base is sleeved in the middle position of the guide rod and slides along the guide rod, the outer end of the sliding base is extended from the housing The double-track grating ruler is fixed on a side of the sliding base close to the PCB assembly along the sliding direction of the sliding base, and the double-track grating ruler slides with the sliding base; the PCB assembly includes a photoelectric conversion chip and a data processing chip, the photoelectric conversion chip and the data processing chip are connected, and an LED light-emitting tube is embedded in the photoelectric conversion chip. When the sliding base slides relative to the shell, the photoelectric conversion chip continuously captures the changes of the sine and cosine light signals reflected by the double-track grating ruler and converts them into changes of electrical signals. The data processing chip processes the electrical signals and outputs the displacement value in the sliding direction of the sliding base.

[0007] Slide holes are provided on both sides of the inner end of the sliding base, and two guide rods are correspondingly provided. The guide rod passes through the slide holes and is fixed in the shell by pressure blocks provided at both ends of the guide rod. Auxiliary springs are sleeved on both ends of the guide rod so that the sliding base is in the middle position of the moving stroke in a free state, and the outer end of the sliding base is fixedly connected to a connecting rod.

[0008] The connecting rod is directly connected to the object to be measured or connected via a fixing seat, and the connecting rod and the fixing seat are connected and fixed via a permanent magnet.

[0009] The double-track grating ruler includes an incremental track subdivided with uniform spacing and an absolute track that is regular or irregular.

[0010] A temperature sensor, a vibration sensor and an anti-electromagnetic interference circuit are arranged in the shell, and the temperature sensor and the vibration sensor are both connected to the data processing chip.

[0011] The sliding base is provided with a sealing sleeve at the portion where it protrudes from the shell. The shell comprises a mounting base and a rear cover, which are connected by screws. A sealing gasket is provided on one side of the rear cover located at the mounting base.

[0012] The LED light emitting tube is a blue light LED light emitting tube.

[0013] The present invention also provides a fan main shaft bearing monitoring system based on a grating type bidirectional displacement sensor, wherein the fan main shaft bearing comprises a bearing inner ring, a bearing outer ring and a fixed base frame from the inside to the outside, the bearing inner ring extends from the bearing outer ring and rotates relative to the bearing outer ring, and the bearing outer ring is fixedly connected to the fixed base frame, characterized in that: the monitoring system comprises a grating type bidirectional displacement sensor, a data processing module and a host computer, the housing of the grating type bidirectional displacement sensor is fixedly connected to the side surface of the bearing outer ring close to the side where the bearing inner ring extends out, and one group of sensing detection units is vertically arranged, the bottom end of the connecting rod of the group of sensing detection units is attached to the outer cylindrical surface of the bearing inner ring, and the sliding base is in the middle position of the moving stroke, so as to monitor the radial runout displacement value of the bearing outer ring and the bearing inner ring; the fixing seat of the other group of sensing detection units is connected to the fixed base frame, and the connecting rod is connected to the fixing seat, so that the group of sensing detection units is installed on the bearing inner ring and the fixed base frame, and the sliding base is horizontal and in the middle position of the moving stroke, so as to monitor the tangential relative displacement value between the bearing outer ring and the fixed base frame;

[0014] The data processing module is installed in the cabin of the fan, the grating type bidirectional displacement sensor is connected to the data processing module, the data processing module is connected to the host computer, the grating type bidirectional displacement sensor transmits the collected data to the data processing module, the data processing module processes the received data, when any one of the radial runout displacement value or the tangential relative displacement value collected by the grating type bidirectional displacement sensor exceeds a certain threshold value, the host computer issues a fan main shaft bearing safety alarm.

[0015] The end of the connecting rod that fits with the outer cylindrical surface of the inner ring of the bearing is a circular surface made of wear-resistant material.

[0016] The data processing chip of the grating type bidirectional displacement sensor is connected to a wireless transmitting module, and the wireless transmitting module is correspondingly provided with a wireless receiving module. The data processing module is connected to the wireless receiving module through a wireless gateway to realize the transmission and reception of the collected data of the grating type bidirectional displacement sensor.

[0017] Compared with the prior art, the technical solution provided by the present invention has the following advantages: 1. The grating type bidirectional displacement sensor provided in the present invention adopts a high-resolution reflective photoelectric principle to monitor the displacement of products within a certain distance, that is, it uses a high-reliability embedded blue light LED light-emitting tube to continuously emit a short-wavelength blue light beam, thereby improving the signal contrast and having excellent anti-shake performance. The sine and cosine light signals reflected by the high-precision dual-track grating scale are collected by the photoelectric conversion chip on the PCB and converted into changes in electrical signals. After the signal is processed by the internal data processing chip MCU of the product, the displacement measured by the product is finally output. It has the characteristics of non-contact, high precision, high reliability and fast response, and can meet the long-term use in various harsh environments.

[0018] 2. The grating type bidirectional displacement sensor provided in the present invention can simultaneously monitor the displacement of the object under test in two directions.

[0019] 3. In the present invention, the sliding base is fixedly connected with a connecting rod, which is directly fixedly connected to the object to be measured or fixedly connected to the object to be measured through a fixed seat. The setting of the fixed seat can meet different installation surface height difference requirements. At the same time, the setting of the connecting rod can realize the adjustment of the monitoring range of the sensor according to actual use.

[0020] 4. The system for monitoring the status of the fan main shaft provided in the present invention is based on a grating type bidirectional displacement sensor. The system simultaneously monitors the radial runout displacement of the fan main shaft bearing outer ring relative to the bearing inner ring and the tangential relative displacement between the bearing outer ring and the fixed base frame through the grating type bidirectional displacement sensor, thereby monitoring the status of the fan main shaft bearing in real time and effectively alarming for abnormal status of the main shaft bearing. The system has a simple structure and low cost, and can directly and effectively identify the real-time operating status of the fan main shaft bearing. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram of the internal structure of the grating type bidirectional displacement sensor of the present invention;

[0022] Figure 2 Schematic diagram of the external structure of the grating type bidirectional displacement sensor in the present invention;

[0023] Figure 3 A top view of the grating type bidirectional displacement sensor of the present invention;

[0024] Figure 4 This is a working principle diagram of the grating type bidirectional displacement sensor in the present invention;

[0025] Figure 5 It is a cross-sectional schematic diagram of the installation of the grating type bidirectional displacement sensor on the main shaft bearing of the fan in the present invention;

[0026] Figure 6It is a three-dimensional schematic diagram of the installation of the grating type bidirectional displacement sensor on the main shaft bearing of the fan in the present invention;

[0027] Figure 7 It is a side view of the installation of the grating type bidirectional displacement sensor in the present invention on the main shaft bearing of the fan;

[0028] Figure 8 It is a front view of the installation of the grating type bidirectional displacement sensor on the main shaft bearing of the fan in the present invention;

[0029] Fig. 9 for Figure 8 A magnified view of the local C in the middle;

[0030] Fig.10 The working principle block diagram of the fan main shaft bearing monitoring system of the present invention;

[0031] In the figure: 1-housing, 11-mounting base, 12-back cover, 2-PCB assembly, 21-photoelectric conversion chip, 3-first sensing detection unit, 31-first sliding base, 32-first guide rod, 33-first double-track grating ruler, 34-first pressure block, 35-first auxiliary spring, 36-first connecting rod, 37-first fixed seat, 4-second sensing detection unit, 41-second sliding base, 42-second guide rod, 43-second double-track grating ruler, 44-second pressure block, 45-second auxiliary spring, 46-second connecting rod, 47-second fixed seat, 48-support plate, 5-permanent magnet, 6-sealing gasket, 7-first sealing sleeve, 8-second sealing sleeve, 9-jack, 100-bearing inner ring, 200-bearing outer ring, 300-fixed base, 400-fastening bolts, 500-rotor bearing, 600-grating type bidirectional displacement sensor. DETAILED DESCRIPTION

[0032] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited to the following embodiments.

[0033] The structure of the grating type bidirectional displacement sensor provided in this embodiment is as follows Figure 1 to Figure 3 As shown, it comprises a housing 1 fixedly connected to the object to be measured, and a sensor module and a circuit module located in the housing, wherein the circuit module is connected to the sensor module. A socket 9 for connecting the sensor module and the circuit module is provided on the housing.

[0034] The sensing module includes two groups of sensing detection units and a PCB assembly 2 located between the two groups of sensing detection units. The three are arranged in parallel up and down, and the two groups of sensing detection units are perpendicular to each other in space; specifically, from bottom to top, they are the first sensing detection unit 3, the PCB assembly, and the second sensing detection unit 4. The grating type bidirectional displacement sensor is fixed on the surface of the object to be measured, and the monitoring direction is parallel to the direction of the first sensing detection unit and the second sensing detection unit. When the object to be measured is subjected to external force and causes relative displacement, the grating type bidirectional displacement sensor can simultaneously collect the nanometer-level displacement of the object to be measured in two directions when the external force is applied, so as to realize the simultaneous monitoring of the displacement in two directions.

[0035] Specifically, the first sensing detection unit includes a first sliding base 31, a first guide rod 32 and a first double-track grating ruler 33. In this embodiment, slideway holes are arranged on both sides of the inner end of the first sliding base, and two first guide rods are arranged correspondingly. The first guide rod passes through the slideway holes and is fixed in the housing through the first pressing blocks 34 arranged at both ends of the first guide rod. The inner end of the first sliding base slides along the first guide rod, and both ends of the first guide rod are sleeved with first auxiliary springs 35, so that the first sliding base is in the middle position of the moving stroke in a free state. The outer end of the first sliding base extends out from the housing and is connected and fixed to the object to be measured. In order to overcome the problem that the installation surface of the monitoring target is uneven and difficult to install, specifically, the outer end of the first sliding base is fixedly connected with a first connecting rod 36, and the first connecting rod is directly connected to the object to be measured or connected through a first fixed seat 37. The first double-track grating ruler is fixed to a side of the first sliding base close to the PCB assembly (i.e., the upper surface of the first sliding base in this embodiment) along the sliding direction of the first sliding base, and the first double-track grating ruler slides with the first sliding base.

[0036] The second sensing detection unit also includes a second sliding base 41, a second guide rod 42 and a second double-track grating ruler 43. The connection relationship between the second sensing detection unit and the first sensing detection unit is the same, except that the whole is installed in a direction perpendicular to the first sensing detection unit. Specifically, the second sensing detection unit also uses a second pressing block 44, a support plate 48, a second auxiliary spring 45 and a second connecting rod 46 when installing. The second double-track grating ruler is fixed to a side of the second sliding base close to the PCB assembly (i.e., the lower surface of the second sliding base in this embodiment) along the sliding direction of the second sliding base, and the second double-track grating ruler slides with the second sliding base. The second connecting rod is directly connected to the object to be measured or connected through a second fixed seat 47.

[0037] In this embodiment, the displacement in two directions can be monitored simultaneously by the first sensing detection unit and the second sensing detection unit, and the structure of the first fixing seat and the second fixing seat can be cancelled or adjusted according to the actual installation requirements to meet different installation surface height difference requirements. When the first connecting rod is connected to the object to be measured through the first fixing seat, and the second connecting rod is connected to the object to be measured through the second fixing seat, the first connecting rod, the second connecting rod, the first fixing seat and the second fixing seat are all connected with permanent magnets 5 and fixed together by the strong magnetic stable adsorption of the permanent magnets to avoid distortion of the test results caused by ambient temperature and vibration. By adjusting the structure of the first fixing seat and the second fixing seat, the grating type bidirectional displacement sensor can meet the installation requirements when the installation surface is uneven.

[0038] In this embodiment, the first double-track grating ruler is the same as the second double-track grating ruler, both of which include an incremental track A subdivided with uniform spacing and an absolute track B with a certain regular and irregular pattern. The PCB assembly includes a photoelectric conversion chip 21 and a data processing chip, which are connected to the data processing chip. A blue light LED light tube is embedded on the photoelectric conversion chip, and the LED light tube continuously emits a short-wavelength blue light beam, which improves the signal contrast and has excellent anti-shake performance. When the short-wavelength blue light beam is irradiated onto the first double-track grating ruler, the incremental track A reflects a regular and uniform sine light wave, and the absolute track B reflects a regular and irregular cosine light wave. The two groups of reflected light wave intensities are superimposed (where the light wave intensity reflected by the incremental track A is a fixed change law, and the light wave intensity reflected by the absolute track B is a known non-fixed change law), and the photoelectric conversion chip continuously captures the sine and cosine light signals reflected by the first double-track grating ruler and processes the signals, and outputs a certain regular electrical signal. When the first sliding substrate slides relative to the housing, the photoelectric conversion chip continuously captures the changes in the sine and cosine light signals reflected by the double-track grating ruler and converts them into changes in electrical signals. The data processing chip processes the electrical signals and outputs the displacement value of the sliding direction of the first sliding substrate. Its working principle is as follows: Figure 4 As shown. When the object under test in the monitoring direction of the second sliding substrate undergoes relative displacement, the photoelectric conversion chip correspondingly and continuously captures the changes in the sine and cosine light signals reflected by the second dual-track grating ruler and converts them into changes in electrical signals, and the data processing chip outputs the relative displacement value corresponding to this direction. Specifically, the data processing chip can adopt an MCU electronic control chip. The grating type bidirectional displacement sensor provided in this embodiment has a resolution of up to 1nm, has high-precision displacement measurement, and the range can be adjusted according to actual use.

[0039] When the surrounding environment changes (temperature changes, vibration environment changes), the accuracy of the product itself will inevitably change due to temperature deformation and vibration. To overcome this defect, a temperature sensor, a vibration sensor and an anti-electromagnetic interference circuit are arranged in the shell in this embodiment, and the temperature sensor and the vibration sensor are connected to the data processing chip. Specifically, the temperature sensor is a precision integrated digital temperature sensor with high resolution characteristics and a measurement accuracy of ±0.1°C. It can collect temperature data of the external environment in real time and transmit the sampled value to the data processing chip. The vibration sensor uses the industry-leading chip with high resolution, extremely low power consumption and long-term stability. The resolution of the vibration sensor is 0.5mg, the measurement range is ±10g, and the vibration amount of the X-axis, Y-axis and Z-axis can be collected at the same time. The temperature sensor and the vibration sensor convert the collected ambient temperature and vibration data into level signals and transmit them to the data processing chip; the data processing chip corrects the displacement of the measurement result through the correction program pre-set inside the product, thereby automatically correcting the measurement error caused by changes in ambient temperature and ambient vibration, thereby greatly improving the measurement accuracy of the product's continuous monitoring.

[0040] Error correction of grating type bidirectional displacement sensor: simulate the actual installation and use environment of grating type bidirectional displacement sensor, through a large number of tests simulating environmental temperature changes and vibration changes, statistically calculate the product's measurement value offset caused by temperature deformation and vibration, and set the correction program according to the statistical results. The anti-electromagnetic interference circuit can shield the interference of the outside world to the grating type bidirectional displacement sensor, and the product stability is extremely strong.

[0041] In this embodiment, the housing includes a mounting base 11 and a back cover 12. The mounting base and the back cover are connected by screws to facilitate the assembly of the grating type bidirectional displacement sensor. The housing is made of metal material. After the sensor module and the circuit module in the housing are assembled, a sealing gasket 6 is laid between the housing and the back cover, and then the back cover is covered and the screws are tightened; the first sliding base and the second sliding base are respectively provided with a first sealing sleeve 7 and a second sealing sleeve 8 at the part extending from the housing. The housing is sealed with a sealing gasket and a sealing sleeve on all sides, and the protection level can reach IP67, which can meet the long-term use in various harsh environments.

[0042] Based on the grating type bidirectional displacement sensor provided by the present invention, the present invention also provides a fan main shaft bearing monitoring system. The fan main shaft bearing includes a bearing inner ring 100, a bearing outer ring 200 and a fixed base frame 300 from the inside to the outside, as shown in FIG. Figure 5The inner ring of the bearing extends out from the outer ring of the bearing and rotates relative to the outer ring of the bearing. The outer ring of the bearing is fixedly connected to the fixed base. Specifically, the outer ring of the bearing is connected to the fixed base by fastening bolts 400. There is a rotor bearing 500 between the outer ring of the bearing and the inner ring of the bearing. When the fan is running, the outer ring of the bearing continuously bears the radial load of the inner ring of the bearing and the tangential torque caused by the rotation of the inner ring of the bearing.

[0043] The installation diagram of the fan main shaft bearing monitoring system is as follows: Figures 5 to 8 As shown, it includes a grating type bidirectional displacement sensor 600, a data processing module and a host computer (the data processing module and the host computer are not shown in the figure), the shell of the grating type bidirectional displacement sensor is fixedly connected to the side of the outer ring of the bearing close to the side where the inner ring of the bearing protrudes, and one group of sensing detection units (i.e., the above-mentioned first sensing detection unit) is vertically arranged, and the bottom end of the connecting rod of this group of sensing detection units is directly attached to the outer cylindrical surface of the inner ring of the bearing (the sensing detection unit does not include a fixed seat), and the auxiliary spring inside the grating type bidirectional displacement sensor is limited so that the connecting rod can be stably attached to the outer cylindrical surface of the inner ring of the bearing, and in the initial state, its sliding base is in the middle position of the moving stroke, so as to monitor the radial runout displacement value of the outer ring of the bearing and the inner ring of the bearing. Specifically, the end of the connecting rod that is attached to the outer cylindrical surface of the inner ring of the bearing is a circular surface made of wear-resistant material, such as Fig. 9 shown.

[0044] At the same time, the fixing seat of another set of sensing detection units (i.e., the second sensing detection unit) is connected to the fixed base, and its connecting rod is connected to the fixing seat, so that the sensing detection unit is installed on the inner ring of the bearing and the fixed base. In the initial state, its sliding base is horizontal and in the middle position of the moving stroke, so as to monitor the tangential relative displacement value between the outer ring of the bearing and the fixed base. At this time, the sensing detection unit includes a fixing seat, so as to meet the height difference requirements on different installation surfaces.

[0045] The data processing module is installed in the cabin of the wind turbine, and the grating type bidirectional displacement sensor is connected to the data processing module. Specifically, the data processing chip of the grating type bidirectional displacement sensor is connected to the wireless transmitting module, and the wireless transmitting module is correspondingly provided with a wireless receiving module. The data processing module is connected to the wireless receiving module through a wireless gateway to realize the transmission and reception of the data collected by the grating type bidirectional displacement sensor. Fig.10 The data processing module is connected to the host computer, and the grating type bidirectional displacement sensor transmits the collected data to the data processing module through wireless transmission. The data processing module processes the received data in real time and can accurately determine the current working state of the fan main shaft bearing. When any of the radial runout displacement value or tangential relative displacement value collected by the grating type bidirectional displacement sensor exceeds a certain threshold, the host computer issues a fan main shaft bearing safety alarm.

[0046] The specific threshold alarm logic is: when the spindle bearing is in normal condition, the radial runout displacement value and tangential relative displacement value monitored by the grating type bidirectional displacement sensor are within a certain safety range; when the spindle bearing wear affects the bearing safety, the concentricity of the bearing outer ring and the bearing inner ring will be offset to a certain extent, and the radial runout displacement value monitored by the grating type bidirectional displacement sensor will increase accordingly; when the connecting bolts between the bearing outer ring and the fixed base are loose or broken, the tangential relative position between the bearing outer ring and the fixed base will be offset to a certain extent, and the tangential relative displacement value monitored by the grating type bidirectional displacement sensor will increase accordingly. When the host computer alarms, the maintenance personnel can quickly find the problem point according to the alarm prompt to avoid greater irreversible safety hazards of the fan.

[0047] Specific threshold setting logic: Through three-dimensional force simulation analysis of data on normal spindle bearings, different degrees of spindle bearing wear, and different numbers of loose connection bolts between the bearing outer ring and the fixed base, the relative radial runout displacement value changes between the bearing outer ring and the bearing inner ring and the tangential relative displacement value changes between the bearing outer ring and the fixed base are calculated, and verified through a large number of experimental tests to finally determine the safety threshold range when the spindle bearing is normal.

Claims

1. A grating type bidirectional displacement sensor, comprising a housing fixedly connected to the object to be measured, and a sensor module and a circuit module located in the housing, wherein the circuit module is connected to the sensor module, characterized in that: The sensing module includes two groups of sensing detection units and a PCB assembly located between the two groups of sensing detection units. The three are arranged in parallel up and down, the two groups of sensing detection units are perpendicular to each other in space, and the PCB assembly is fixed in the shell; the sensing detection unit includes a sliding base, a guide rod and a double-track grating ruler, wherein the guide rod is fixed in the shell, the inner end of the sliding base is sleeved in the middle position of the guide rod and slides along the guide rod, the outer end of the sliding base extends from the shell and is connected and fixed to the object to be measured, the double-track grating ruler is fixed to a side of the sliding base close to the PCB assembly along the sliding direction of the sliding base, and the double-track grating ruler slides with the sliding base; the PCB assembly includes a photoelectric conversion chip and a data processing chip, the photoelectric conversion chip and the data processing chip are connected, and an LED light-emitting tube is embedded in the photoelectric conversion chip. When the sliding base slides relative to the shell, the photoelectric conversion chip continuously captures the changes in the sine and cosine light signals reflected by the double-track grating ruler and converts them into changes in electrical signals, and the data processing chip processes the electrical signals and outputs the displacement value of the sliding direction of the sliding base.

2. The grating type bidirectional displacement sensor according to claim 1, characterized in that: Slide holes are provided on both sides of the inner end of the sliding base, and two guide rods are correspondingly provided. The guide rod passes through the slide holes and is fixed in the shell by pressure blocks provided at both ends of the guide rod. Auxiliary springs are sleeved on both ends of the guide rod so that the sliding base is in the middle position of the moving stroke in a free state, and the outer end of the sliding base is fixedly connected to a connecting rod.

3. The grating type bidirectional displacement sensor according to claim 2, characterized in that: The connecting rod is directly connected to the object to be measured or connected via a fixing seat, and the connecting rod and the fixing seat are connected and fixed via a permanent magnet.

4. The grating type bidirectional displacement sensor according to claim 2, characterized in that: The dual-track grating ruler includes an incremental track subdivided with uniform spacing and an absolute track that is regular and irregular. When a short-wavelength blue light beam is irradiated onto the dual-track grating ruler, the incremental track reflects a regular sinusoidal light wave with a fixed variation pattern in intensity, and the absolute track reflects a regular and irregular cosine light wave with a known non-fixed variation pattern in intensity.

5. The grating type bidirectional displacement sensor according to claim 2, characterized in that: A temperature sensor, a vibration sensor and an anti-electromagnetic interference circuit are arranged in the shell, and the temperature sensor and the vibration sensor are both connected to the data processing chip.

6. The grating type bidirectional displacement sensor according to claim 2, characterized in that: The sliding base is provided with a sealing sleeve at the portion where it protrudes from the shell. The shell comprises a mounting base and a rear cover, which are connected by screws. A sealing gasket is provided on one side of the rear cover located at the mounting base.

7. The grating type bidirectional displacement sensor according to claim 2, characterized in that: The LED light emitting tube is a blue light LED light emitting tube.

8. A fan main shaft bearing monitoring system based on a grating type bidirectional displacement sensor according to any one of claims 2 to 7, wherein the fan main shaft bearing comprises, from inside to outside, a bearing inner ring, a bearing outer ring and a fixed base frame, the bearing inner ring extends from the bearing outer ring and rotates relative to the bearing outer ring, and the bearing outer ring is fixedly connected to the fixed base frame, characterized in that: The monitoring system includes a grating type bidirectional displacement sensor, a data processing module and a host computer. The housing of the grating type bidirectional displacement sensor is fixedly connected to the side of the outer ring of the bearing close to the side where the inner ring of the bearing protrudes, and one group of sensing detection units is vertically aligned, and the bottom end of the connecting rod of the group of sensing detection units is attached to the outer circumferential surface of the inner ring of the bearing, and its sliding base is in the middle position of the moving stroke, so as to monitor the radial runout displacement value of the outer ring of the bearing and the inner ring of the bearing; the fixed seat of the other group of sensing detection units is connected to the fixed base, and its connecting rod is connected to the fixed seat, so that the group of sensing detection units is installed on the inner ring of the bearing and the fixed base, and its sliding base is horizontal and in the middle position of the moving stroke, so as to monitor the tangential relative displacement value between the outer ring of the bearing and the fixed base; The data processing module is installed in the cabin of the fan, the grating type bidirectional displacement sensor is connected to the data processing module, the data processing module is connected to the host computer, the grating type bidirectional displacement sensor transmits the collected data to the data processing module, the data processing module processes the received data, when any one of the radial runout displacement value or the tangential relative displacement value collected by the grating type bidirectional displacement sensor exceeds a certain threshold value, the host computer issues a fan main shaft bearing safety alarm.

9. The fan main shaft bearing monitoring system according to claim 8, characterized in that: The end of the connecting rod that fits with the outer cylindrical surface of the inner ring of the bearing is a circular surface made of wear-resistant material.

10. The fan main shaft bearing monitoring system according to claim 8, characterized in that: The data processing chip of the grating type bidirectional displacement sensor is connected to a wireless transmitting module, and the wireless transmitting module is correspondingly provided with a wireless receiving module. The data processing module is connected to the wireless receiving module through a wireless gateway to realize the transmission and reception of the collected data of the grating type bidirectional displacement sensor.

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