Water turbine auxiliary structure with main shaft crack self-checking function

Abstract

The invention relates to the technical field of water turbine detection, in particular to a water turbine auxiliary structure with a main shaft crack self-checking function. The water turbine auxiliary structure comprises a water turbine main shaft, an annular support and a protective shell, and the annular support and the protective shell are coaxially and fixedly arranged on the outer side of the water turbine main shaft in a sleeving mode and are concentric with the water turbine main shaft; the annular support is connected with a water turbine rack, a plurality of elastic supporting pieces are annularly distributed on the annular support and the protective shell, and a crack detection structure is arranged in the protective shell; the crack detection structure comprises an attaching block which is coaxial with the water turbine main shaft and is annularly distributed, a piezoelectric sensor is embedded in the inner side of the attaching block, the inner side of the piezoelectric sensor makes contact with the water turbine main shaft, and a radial detection assembly is connected to the outer side of the attaching block in a bolted mode. The water turbine auxiliary structure with the main shaft crack self-detection function has the advantages that online dual detection of the water turbine main shaft is achieved, and the detection sensitivity and accuracy are improved.

Description

Technical Field

[0001] This invention relates to the field of turbine testing technology, specifically to a turbine auxiliary structure with a self-inspection function for main shaft cracks. Background Technology

[0002] As is well known, the turbine main shaft is the core transmission component in a hydroelectric generator set that connects the turbine runner and the generator rotor. It belongs to the category of hydraulic machinery and auxiliary equipment in power equipment and is mainly used in vertical hydroelectric generator sets.

[0003] The turbine main shaft is a core component that transmits torque and bears axial force. Under prolonged high speed, heavy load, and alternating stress, it is prone to cracking. Failure to detect cracks in time can lead to shaft breakage and a major safety accident. Current technologies for main shaft crack detection primarily rely on offline testing (such as magnetic particle testing and ultrasonic testing) or a single online sensor (such as a vibration sensor), which has the following drawbacks:

[0004] 1. Offline detection requires the machine to be shut down, and cannot monitor crack initiation and propagation in real time;

[0005] 2. Single online sensors are susceptible to environmental interference (such as vibration and temperature), resulting in low detection accuracy and difficulty in distinguishing cracks from other faults (such as bearing wear). Summary of the Invention

[0006] (a) Technical problems to be solved

[0007] To address the shortcomings of existing technologies, this invention provides a turbine auxiliary structure with a self-inspection function for main shaft cracks, which has the advantages of enabling online dual detection of the turbine main shaft and improving detection sensitivity and accuracy.

[0008] (II) Technical Solution

[0009] The above-mentioned technical objective of the present invention is achieved through the following technical solution: a turbine auxiliary structure with a self-inspection function for main shaft cracks, comprising a turbine main shaft, an annular support and a protective shell, wherein the annular support and the protective shell are coaxially fixedly sleeved on the outside of the turbine main shaft and arranged concentrically with the turbine main shaft, the annular support is connected to the turbine frame, and the annular support and the protective shell are provided with a plurality of elastic support members in a ring, and the inside of the protective shell is provided with a crack detection structure;

[0010] The crack detection structure includes a bonding block coaxial with the turbine main shaft and arranged in a ring. A piezoelectric sensor is embedded in the inner side of the bonding block, and the inner side of the piezoelectric sensor is in contact with the turbine main shaft. A radial detection component is bolted to the outer side of the bonding block, and the other end of the radial detection component is bolted to the inner wall of the protective shell. An axial detection component is bolted to the top and bottom of the inside of the protective shell, and the axial detection component is fitted on the outer side of the turbine main shaft.

[0011] By adopting the above technical solution and setting up a crack detection structure, the crack detection structure can solve the problems of offline lag, single-dimensional misjudgment, and insensitivity to early cracks in existing traditional detection methods through the coordinated detection of radial mechanical amplification detection, axial deformation force detection, and piezoelectric sensor assistance. The radial detection component amplifies the small radial vibration of the main shaft with the help of the wedge structure, so that the subtle displacement caused by early cracks can be accurately captured. The axial detection component converts axial movement into force signal through the ring elastic contact plate, forming a double verification with the radial signal, avoiding misjudgment due to non-crack factors such as bearing wear. The piezoelectric sensor senses the stress change on the main shaft surface in real time, helping to confirm the initiation of cracks. The combination of the three realizes real-time monitoring, double verification, and early warning, which greatly improves the sensitivity and accuracy of crack detection, and does not require shutdown, making it suitable for the continuous operation requirements of water turbines.

[0012] The invention is further configured such that: the radial detection assembly includes two support plates, one of which is bolted to the protective housing; an active wedge is slidably disposed between opposite sides of the two support plates; a connecting rod is bolted to the active wedge near the bonding block, and the other side of the connecting rod is connected to the bonding block; a limiting frame is bolted between the tops of the two support plates; a driven wedge is slidably disposed inside the limiting frame; the bottom of the driven wedge contacts the active wedge; a radial displacement sensor is bolted to the top of the limiting frame; and a certain gap exists between the driven wedge and the probe of the radial displacement sensor.

[0013] By employing the above technical solution, a radial detection component is installed. When the turbine main shaft vibrates radially due to cracks, the mating block moves radially with the turbine main shaft. This movement is achieved by pushing the active wedge along the support plate via a connecting rod. Since the inclined surface of the active wedge contacts the driven wedge, it pushes the driven wedge to slide upward along the limit frame. The radial displacement sensor detects the displacement change of the driven wedge and converts the mechanical displacement into an electrical signal. If there are no cracks in the main shaft, the active wedge only moves slightly due to normal vibration, and the driven wedge displacement remains stable. If cracks exist, the radial vibration of the main shaft intensifies, the movement amplitude of the active wedge increases, and the displacement of the driven wedge is amplified synchronously, allowing the sensor to capture the abnormal signal. By amplifying the minute radial vibration of the main shaft through the wedge structure, the sensor can accurately capture the subtle displacement caused by early cracks, solving the problem of traditional sensors being insensitive to early cracks.

[0014] The present invention is further configured such that: a guide slider is welded to the side of the active wedge near the support plate, and the guide slider is slidably disposed inside the support plate; a guide rod passes through the inside of the guide slider; both ends of the guide rod are bolted to the inner wall of the support plate; a return spring is sleeved on the surface of the guide rod, and both ends of the return spring are bolted to the inner wall of the support plate and the guide slider, respectively.

[0015] By adopting the above technical solution, the guide slider and guide rod work together to ensure the accurate movement trajectory of the active wedge, avoiding wedge jamming or detection deviation caused by offset. The reset spring realizes the automatic reset of the active wedge, ensuring that the detection component is always in standby state, improving the continuity and reliability of detection.

[0016] The present invention is further configured such that: the contact surface of the active wedge and the driven wedge is an inclined surface with an inclination angle of 30°-60°, the contact end of the bonding block with the main shaft is provided with a wear-resistant ceramic head, and the bonding block is connected to the connecting rod through a ball joint structure.

[0017] By adopting the above technical solution, the displacement amplification factor can be precisely controlled through the inclined slope design, thereby improving the sensitivity of early crack detection. Meanwhile, the wear-resistant ceramic head extends the service life of the bonding block and avoids frequent replacement.

[0018] The present invention is further configured such that: the axial detection component includes an annular elastic contact piece, the annular elastic contact piece is sleeved on the outer surface of the turbine main shaft, the outer surface of the annular elastic contact piece is welded with a plurality of connecting plates in an annular shape, the inner wall of the protective shell is bolted with a mounting plate at the position corresponding to the connecting plate, a pre-tightening spring is bolted between the mounting plate and the connecting plate, a transmission rod is bolted to the top of each of the two connecting plates on both sides, and the top of the transmission rod is connected to an axial force sensor through a ball joint structure, the axial force sensor being bolted to the inner wall of the protective shell through the mounting rod.

[0019] Using the above technical solution, by setting up an axial detection component, when the spindle experiences axial movement due to a crack, it pushes the annular elastic contact plate to deform. The annular elastic contact plate stretches or compresses the preload spring through the connecting plate, simultaneously driving the transmission rod to move. The transmission rod transmits the force to the axial force sensor through a ball joint structure, and the sensor converts the force signal into an electrical signal. If the spindle has no crack, the axial movement is minimal, the preload spring deforms only slightly, and the force signal is stable. If a crack exists, the axial movement intensifies, the preload spring deforms more, and the force signal fluctuates abnormally. The annular elastic contact plate can detect the axial movement of the spindle from all angles, with no monitoring blind spots, and compared to directly detecting axial displacement, it can better reflect abnormal spindle stress, auxiliary zone cracks, bearing wear, and other faults.

[0020] The present invention is further configured such that: the radial displacement sensor is an eddy current sensor, the distance between its detection end and the driven wedge is 0.5-1mm, and the axial force sensor is a strain gauge force sensor, the measurement range of which is 0-500N.

[0021] The above technical solution utilizes eddy current sensors for non-contact detection, avoiding mechanical wear and adapting to high-speed spindle rotation scenarios. Meanwhile, strain gauge force sensors offer high measurement accuracy, capturing minute force fluctuations and adapting to subtle axial force changes caused by early cracks. Furthermore, both types of sensors provide stable signals and strong anti-interference capabilities, ensuring reliable detection data and providing accurate basis for crack identification.

[0022] The invention is further configured such that: the elastic support member includes several sets of spring dampers distributed circumferentially along the inner side of the annular bracket, each set of spring dampers includes an outer sleeve and an inner slide rod, the outer sleeve is rotatably connected to the annular bracket, one end of the inner slide rod is rotatably connected to the protective shell, and the other end extends into the outer sleeve and is slidably connected to the outer sleeve, a movable plate is bolted to one end of the inner slide rod extending into the outer sleeve, and buffer springs are provided between the movable plate and the inner wall of the outer sleeve and on the surface of the inner slide rod.

[0023] By adopting the above technical solution and setting up elastic support components, when the frame or protective shell vibrates, the inner slide rod slides along the outer sleeve, the movable plate compresses or stretches the buffer spring, and at the same time squeezes the oil in the outer sleeve. The vibration energy is absorbed by the spring force and oil damping. If the spindle has a slight radial displacement, the outer sleeve and the inner slide rod can be flexibly rotated through the rotating frame to adjust the angle to adapt to the displacement, ensuring that the protective shell and the spindle are always concentric. Through the synergy of spring damping and oil buffering, the interference of external vibration on the detection components is effectively isolated, and the sensor false triggering caused by vibration is avoided.

[0024] The invention is further configured such that: the interior of the outer sleeve is filled with oil, and one end of both the outer sleeve and the inner slide rod is rotatably connected to a rotating frame; the outer sleeve and the inner slide rod are rotatably connected to the annular bracket and the protective shell respectively through the rotating frame.

[0025] By adopting the above technical solution, the damping effect is enhanced by filling with oil, which is more thorough than simple spring vibration reduction and effectively filters high-frequency vibration interference. Meanwhile, the rotating frame enables multi-angle adaptive adjustment of the elastic support components, which can adapt to the complex movement of the main shaft during turbine operation and avoid component damage caused by rigid support.

[0026] The present invention is further configured such that: the crack detection structure further includes a signal processing module, the signal processing module comprising:

[0027] The signal acquisition unit is used to receive the voltage signal output by the radial displacement sensor and the current signal output by the axial force sensor.

[0028] The feature extraction unit is used to perform time-domain analysis (extracting peak value and variance) and frequency-domain analysis (extracting second and third harmonic amplitude) on the acquired signal.

[0029] The judgment unit has a preset crack judgment threshold. When the peak value of the radial displacement signal exceeds 0.1 mm and the proportion of the second harmonic amplitude exceeds 15%, or the fluctuation of the axial force signal exceeds 50 N and the duration exceeds 5 s, the turbine main shaft is judged to have a crack.

[0030] The above technical solution automates data acquisition, analysis, and judgment through a signal processing module, eliminating the need for manual data analysis and improving detection efficiency. The combined analysis of time and frequency domains accurately identifies crack characteristic frequencies, avoiding misjudging faults such as bearing wear as cracks. The preset threshold can be adjusted according to the turbine model, adapting to different operating conditions and demonstrating strong versatility.

[0031] The invention is further configured such that: the protective shell is composed of two half-shells, and the two half-shells are connected by bolts; the top and bottom of the two half-shells are both embedded with sealing rings, and the inner side of the sealing rings is in rotational contact with the turbine main shaft.

[0032] The above technical solution facilitates the installation of the protective shell through its detachable design; the sealing ring achieves dynamic sealing, balancing spindle rotation and protection, and preventing damage to the detection components due to moisture and dust accumulation.

[0033] (III) Beneficial Effects

[0034] Compared with the prior art, the present invention provides a turbine auxiliary structure with a self-inspection function for main shaft cracks, which has the following beneficial effects:

[0035] This turbine auxiliary structure with self-inspection function for main shaft cracks solves the problems of offline lag, single-dimensional misjudgment, and insensitivity to early cracks in existing traditional detection methods by using radial mechanical amplification detection, axial deformation force detection, and piezoelectric sensor-assisted detection. The radial detection component amplifies the tiny radial vibration of the main shaft with a wedge structure, allowing the subtle displacement caused by early cracks to be accurately captured. The axial detection component converts axial movement into force signals through annular elastic contact plates, forming a dual verification with the radial signal to avoid misjudgment due to non-crack factors such as bearing wear. The piezoelectric sensor senses the stress change on the main shaft surface in real time, helping to confirm crack initiation. The combination of the three achieves real-time monitoring, dual verification, and early warning, greatly improving the sensitivity and accuracy of crack detection, and does not require shutdown, making it suitable for the continuous operation requirements of turbines.

[0036] By incorporating elastic support components, which utilize a composite structure of spring damping and oil buffering, the elastic support components combine dynamic isolation and stable support functions. On one hand, the buffer springs and oil can absorb the vibrations transmitted by the frame and the vibration interference from the protective housing itself, preventing vibrations from causing false triggering of the detection components. On the other hand, the sliding cooperation between the outer sleeve and the inner slide rod, combined with the flexible rotation of the rotating frame, can accommodate minor radial offsets and axial movements during spindle operation, ensuring that the protective housing and the spindle are always concentric, providing a stable detection reference for the detection components. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0038] Figure 2 This is a schematic diagram showing the connection between the crack detection structure, the protective shell, and the turbine body in this invention;

[0039] Figure 3 This is a schematic diagram of the radial detection component structure in this invention;

[0040] Figure 4 This is a schematic diagram showing the connection between the active wedge and the support plate in this invention;

[0041] Figure 5 This is a schematic diagram of the axial detection component structure in this invention;

[0042] Figure 6 This is a schematic diagram showing the connection between the protective outer shell and the turbine main shaft in this invention;

[0043] Figure 7 This is a schematic diagram of the elastic support structure in this invention.

[0044] In the diagram: 1. Turbine main shaft; 2. Annular support; 3. Protective housing; 4. Elastic support component; 41. Outer sleeve; 42. Inner slide rod; 43. Movable plate; 44. Buffer spring; 5. Crack detection structure; 51. Adhesive block; 52. Piezoelectric sensor; 53. Radial detection assembly; 531. Support plate; 532. Active wedge; 533. Connecting rod; 534. Limiting frame; 535. Driven wedge; 536. Radial displacement sensor; 54. Axial detection assembly; 541. Annular elastic contact piece; 542. Connecting plate; 543. Mounting plate; 544. Preload spring; 545. Transmission rod; 546. Axial force sensor; 6. Guide slider; 7. Guide rod; 8. Return spring; 9. Rotating frame; 10. Sealing ring. Detailed Implementation

[0045] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0046] Please see Figure 1-7 A turbine auxiliary structure with a self-inspection function for main shaft cracks includes a turbine main shaft 1, an annular support 2, and a protective shell 3. The annular support 2 and the protective shell 3 are coaxially fixedly sleeved on the outside of the turbine main shaft 1 and arranged concentrically with the turbine main shaft 1. The annular support 2 is connected to the turbine frame. The annular support 2 and the protective shell 3 are provided with a number of elastic support members 4 in an annular arrangement. The protective shell 3 is provided with a crack detection structure 5 inside.

[0047] The crack detection structure 5 includes a bonding block 51 coaxial with the turbine main shaft 1 and arranged in a ring. A piezoelectric sensor 52 is embedded inside the bonding block 51, and the inner side of the piezoelectric sensor 52 contacts the turbine main shaft 1. A radial detection component 53 is bolted to the outer side of the bonding block 51, and the other end of the radial detection component 53 is bolted to the inner wall of the protective shell 3. Axial detection components 54 are bolted to the top and bottom of the protective shell 3, and the axial detection components 54 are fitted onto the outer side of the turbine main shaft 1. By setting up the crack detection structure 5, the crack detection structure 5 achieves detection through radial mechanical amplification, axial deformation force detection, and the assistance of the piezoelectric sensor 52. The same detection method can solve the problems of offline lag, single-dimensional misjudgment, and insensitivity to early cracks in existing traditional detection methods. The radial detection component 53 amplifies the small radial vibration of the main shaft with the help of the wedge structure, so that the subtle displacement caused by early cracks can be accurately captured. The axial detection component 54 converts the axial movement into a force signal, which forms a dual verification with the radial signal to avoid misjudgment due to non-crack factors such as bearing wear. The piezoelectric sensor 52 senses the stress change on the main shaft surface in real time to help confirm the initiation of cracks. The combination of the three realizes real-time monitoring, dual verification, and early warning, which greatly improves the sensitivity and accuracy of crack detection, and does not require shutdown, making it suitable for the continuous operation requirements of water turbines.

[0048] The radial detection component 53 includes two support plates 531. The support plates 531 are bolted to the protective housing 3 on one side. An active wedge 532 is slidably disposed between the opposite sides of the two support plates 531. A connecting rod 533 is bolted to the active wedge 532 near the mating block 51, and the other side of the connecting rod 533 is connected to the mating block 51. A limit frame 534 is bolted between the tops of the two support plates 531, and a driven wedge 535 is slidably disposed inside the limit frame 534. The bottom of the driven wedge 535 contacts the active wedge 532. A radial displacement sensor 536 is bolted to the top of the limit frame 534. There is a certain gap between the driven wedge 535 and the probe of the radial displacement sensor 536. By setting the radial detection component 53, when the turbine main shaft 1 experiences radial vibration due to a crack, the mating block 51... As the turbine main shaft 1 moves radially, the connecting rod 533 pushes the active wedge 532 to slide along the support plate 531. Since the inclined surface of the active wedge 532 contacts the driven wedge 535, it pushes the driven wedge 535 to slide upward along the limit frame 534. The radial displacement sensor 536 detects the displacement change of the driven wedge 535 and converts the mechanical displacement into an electrical signal. If there is no crack in the main shaft, the active wedge 532 will only move slightly due to normal vibration, and the displacement of the driven wedge 535 will be stable. If there is a crack, the radial vibration of the main shaft will intensify, the movement amplitude of the active wedge 532 will increase, and the displacement of the driven wedge 535 will be amplified synchronously. The sensor will capture the abnormal signal. By amplifying the small radial vibration of the main shaft through the wedge structure, the subtle displacement caused by early cracks can be accurately captured by the sensor, solving the problem that traditional sensors are not sensitive to early cracks.

[0049] The active wedge 532 has a guide slider 6 welded to the side near the support plate 531, and the guide slider 6 is slidably disposed inside the support plate 531. A guide rod 7 runs through the inside of the guide slider 6, and both ends of the guide rod 7 are bolted to the inner wall of the support plate 531. A return spring 8 is sleeved on the surface of the guide rod 7, and both ends of the return spring 8 are bolted to the inner wall of the support plate 531 and the guide slider 6, respectively. Through the cooperation of the guide slider 6 and the guide rod 7, the movement trajectory of the active wedge 532 is ensured to be accurate, avoiding wedge jamming or detection deviation caused by offset. The return spring 8 realizes the automatic reset of the active wedge 532, ensuring that the detection component is always in standby state, improving the continuity and reliability of detection.

[0050] Among them, the contact surfaces of the active wedge 532 and the driven wedge 535 are inclined surfaces with an inclination angle of 30°-60°. The contact end of the bonding block 51 with the spindle is equipped with a wear-resistant ceramic head. The bonding block 51 is connected to the connecting rod 533 through a ball joint structure. The displacement amplification factor is precisely controlled by the inclined surface design, which improves the sensitivity of early crack detection. The wear-resistant ceramic head extends the service life of the bonding block 51 and avoids frequent replacement.

[0051] The axial detection component 54 includes an annular elastic contact piece 541, which is sleeved on the outer surface of the turbine main shaft 1. Several connecting plates 542 are welded annularly to the outer surface of the annular elastic contact piece 541. Mounting plates 543 are bolted to the inner wall of the protective housing 3 at positions corresponding to the connecting plates 542. A preload spring 544 is bolted between the mounting plate 543 and the connecting plates 542. Transmission rods 545 are bolted to the tops of the two connecting plates 542 on both sides, and an axial force sensor 546 is connected to the top of the transmission rod 545 via a ball joint structure. The axial force sensor 546 is bolted to the inner wall of the protective housing 3 via the mounting rod. By setting up the axial detection component 54, when the main shaft experiences axial movement due to cracks, the axial force sensor 546 can detect the axial movement of the turbine main shaft. The annular elastic contact 541 deforms, and the annular elastic contact 541 stretches or compresses the preload spring 544 through the connecting plate 542, while simultaneously driving the transmission rod 545 to move. The transmission rod 545 transmits the force to the axial force sensor 546 through the ball joint structure, and the sensor converts the force signal into an electrical signal. If the spindle has no cracks, the axial movement is minimal, the preload spring 544 deforms only slightly, and the force signal is stable. If cracks exist, the axial movement intensifies, the deformation of the preload spring 544 increases, and the force signal fluctuates abnormally. The annular elastic contact 541 can detect the axial movement of the spindle from all directions, with no monitoring blind spots, and compared with directly detecting axial displacement, it can better reflect abnormal spindle force, auxiliary area cracks, bearing wear, and other faults.

[0052] Among them, the radial displacement sensor 536 is an eddy current sensor, and the distance between its detection end and the driven wedge 535 is 0.5-1mm. The axial force sensor 546 is a strain gauge force sensor with a measurement range of 0-500N. The eddy current sensor performs non-contact detection, avoiding mechanical wear and adapting to high-speed spindle rotation scenarios. The strain gauge force sensor has high measurement accuracy and can capture minute force fluctuations, adapting to the subtle axial force changes caused by early cracks. Both types of sensors have stable signals and strong anti-interference capabilities, ensuring reliable detection data and providing accurate basis for crack judgment.

[0053] The elastic support 4 includes several sets of spring dampers distributed circumferentially along the inner side of the annular bracket 2. Each set of spring dampers includes an outer sleeve 41 and an inner slide rod 42. The outer sleeve 41 is rotatably connected to the annular bracket 2. One end of the inner slide rod 42 is rotatably connected to the protective shell 3, and the other end extends into the outer sleeve 41 and is slidably connected to the outer sleeve 41. A movable plate 43 is bolted to one end of the inner slide rod 42 extending into the outer sleeve 41. Buffer springs 44 are provided between the movable plate 43 and the inner wall of the outer sleeve 41, and on the surface of the inner slide rod 42. The elastic support 4 provides this functionality. When the frame or protective housing 3 vibrates, the inner slide bar 42 slides along the outer sleeve 41, the movable plate 43 compresses or stretches the buffer spring 44, and at the same time squeezes the oil in the outer sleeve 41. The vibration energy is absorbed by the spring force and the oil damping. If the spindle has a slight radial displacement, the outer sleeve 41 and the inner slide bar 42 can be flexibly rotated by the rotating frame 9 to adjust the angle to adapt to the displacement, ensuring that the protective housing 3 and the spindle are always concentric. Through the cooperation of spring damping and oil buffering, the interference of external vibration on the detection components is effectively isolated, and the sensor is prevented from being falsely triggered by vibration.

[0054] The outer sleeve 41 is filled with oil, and one end of both the outer sleeve 41 and the inner slide rod 42 is rotatably connected to a rotating frame 9. The outer sleeve 41 and the inner slide rod 42 are rotatably connected to the annular bracket 2 and the protective shell 3 respectively through the rotating frame 9. The oil filling enhances the damping effect, which is more thorough than simple spring vibration reduction and effectively filters high-frequency vibration interference. The rotating frame 9 enables the elastic support 4 to self-adapt to multiple angles, adapting to the complex movement of the main shaft during turbine operation and avoiding component damage caused by rigid support.

[0055] The crack detection structure 5 also includes a signal processing module, which includes:

[0056] The signal acquisition unit is used to receive the voltage signal output by the radial displacement sensor 536 and the current signal output by the axial force sensor 546.

[0057] The feature extraction unit is used to perform time-domain analysis (extracting peak value and variance) and frequency-domain analysis (extracting second and third harmonic amplitude) on the acquired signal.

[0058] The judgment unit has a preset crack judgment threshold. When the peak value of the radial displacement signal exceeds 0.1 mm and the proportion of the second harmonic amplitude exceeds 15%, or the fluctuation of the axial force signal exceeds 50 N and the duration exceeds 5 s, the turbine main shaft 1 is judged to have a crack. The acquisition, analysis and judgment are automated through the signal processing module, eliminating the need for manual data analysis and improving detection efficiency. The time domain and frequency domain combined analysis accurately identifies the characteristic frequency of cracks, avoiding misjudging faults such as bearing wear as cracks. The preset threshold can be adjusted according to the turbine model to adapt to different working conditions and has strong versatility.

[0059] The protective housing 3 consists of two half-shells connected by bolts. A sealing ring 10 is embedded in the top and bottom of the two half-shells. The inner side of the sealing ring 10 is in rotational contact with the turbine main shaft 1. The detachable design of the protective housing 3 facilitates its installation. The sealing ring 10 achieves dynamic sealing, balancing the rotation of the main shaft with the protection effect, and preventing the detection components from being damaged by moisture or dust accumulation.

[0060] The working principle of this embodiment is as follows: First, the annular bracket 2 is fixed on the turbine frame. The protective shell 3 is connected to the annular bracket 2 through the elastic support 4 to form a stable detection frame. The outer sleeve 41 and the inner slide rod 42 in the elastic support 4 cooperate to adapt to the slight radial displacement of the main shaft. At the same time, the buffer spring 44 and the oil can absorb vibration and avoid external interference. When the main shaft rotates, the crack detection structure 5 starts to work. The piezoelectric sensor 52 on the inner side of the bonding block 51 contacts the surface of the main shaft and senses the stress change on the surface of the main shaft in real time. If a crack appears in the main shaft, radial vibration and axial movement will occur. In the radial direction, the radial vibration of the main shaft drives the bonding block 51 to move. Through the connecting rod 533, the active wedge 532 is pushed to slide along the support plate 531. The guide sliders 6 on both sides of the active wedge 532 move along the guide rod 7 to ensure accurate movement trajectory. The reset spring 8 can make the active wedge 532 reset in time. The moving wedge 532 pushes the driven wedge 535 to slide along the limiting frame 534 via the inclined plane, amplifying the small radial displacement. The radial displacement sensor 536 (eddy current sensor) detects the displacement change of the driven wedge 535 and converts it into a voltage signal. In the axial direction, the axial movement of the spindle causes the annular elastic contact 541 to deform, which stretches or compresses the preload spring 544 through the connecting plate 542, and at the same time drives the transmission rod 545 to move. The transmission rod 545 transmits the force to the axial force sensor 546 (strain gauge force sensor), and the sensor converts the force signal into a current signal. The signal acquisition unit of the signal processing module receives the above voltage and current signals, the feature extraction unit performs time-domain and frequency-domain analysis on the signals and extracts relevant feature values, and the judgment unit compares the feature values ​​with a preset threshold. If the crack judgment condition is met, it is determined that there is a crack in the spindle. The whole process realizes real-time and accurate detection of spindle cracks.

[0061] This specific embodiment is merely an explanation of the present invention and is not intended to limit the invention. Those skilled in the art can make modifications to this embodiment without contributing any inventive step after reading this specification. Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A turbine auxiliary structure with a self-inspection function for main shaft cracks, comprising a turbine main shaft (1), an annular support (2), and a protective shell (3), characterized in that: The annular bracket (2) and the protective shell (3) are coaxially fixedly sleeved on the outside of the turbine main shaft (1) and arranged concentrically with the turbine main shaft (1). The annular bracket (2) is connected to the turbine frame. The annular bracket (2) and the protective shell (3) are arranged in a ring with several elastic support members (4). The protective shell (3) is provided with a crack detection structure (5) inside. The crack detection structure (5) includes a bonding block (51) that is coaxial with the turbine main shaft (1) and arranged in a ring. A piezoelectric sensor (52) is embedded in the inner side of the bonding block (51), and the inner side of the piezoelectric sensor (52) is in contact with the turbine main shaft (1). A radial detection component (53) is bolted to the outer side of the bonding block (51), and the other end of the radial detection component (53) is bolted to the inner wall of the protective shell (3). An axial detection component (54) is bolted to the top and bottom of the protective shell (3), and the axial detection component (54) is fitted on the outer side of the turbine main shaft (1).

2. The turbine auxiliary structure with main shaft crack self-inspection function according to claim 1, characterized in that: The radial detection assembly (53) includes two support plates (531). The support plates (531) are bolted to the protective housing (3) on one side. An active wedge (532) is slidably disposed between the opposite sides of the two support plates (531). A connecting rod (533) is bolted to the side of the active wedge (532) near the bonding block (51), and the other side of the connecting rod (533) is connected to the bonding block (51). A limit frame (534) is bolted between the tops of the two support plates (531), and a driven wedge (535) is slidably disposed inside the limit frame (534). The bottom of the driven wedge (535) is in contact with the active wedge (532). A radial displacement sensor (536) is bolted to the top of the limit frame (534), and there is a certain gap between the driven wedge (535) and the probe of the radial displacement sensor (536).

3. The turbine auxiliary structure with self-inspection function for main shaft cracks according to claim 2, characterized in that: The active wedge (532) has a guide slider (6) welded to the side near the support plate (531), and the guide slider (6) is slidably disposed inside the support plate (531). A guide rod (7) runs through the inside of the guide slider (6), and both ends of the guide rod (7) are bolted to the inner wall of the support plate (531). A return spring (8) is sleeved on the surface of the guide rod (7), and both ends of the return spring (8) are bolted to the inner wall of the support plate (531) and the guide slider (6) respectively.

4. The turbine auxiliary structure with self-inspection function for main shaft cracks according to claim 2, characterized in that: The contact surfaces of the active wedge (532) and the driven wedge (535) are inclined surfaces with an inclination angle of 30°-60°. The contact end of the bonding block (51) with the main shaft is provided with a wear-resistant ceramic head. The bonding block (51) is connected to the connecting rod (533) through a ball joint structure.

5. A turbine auxiliary structure with self-inspection function for main shaft cracks according to claim 2, characterized in that: The axial detection assembly (54) includes an annular elastic contact piece (541), which is sleeved on the outer surface of the turbine main shaft (1). The outer surface of the annular elastic contact piece (541) is welded with several connecting plates (542) in an annular shape. The inner wall of the protective shell (3) is bolted with a mounting plate (543) corresponding to the position of the connecting plate (542). A pre-tightening spring (544) is bolted between the mounting plate (543) and the connecting plate (542). A transmission rod (545) is bolted to the top of each of the two connecting plates (542) on both sides. An axial force sensor (546) is connected to the top of the transmission rod (545) through a ball joint structure. The axial force sensor (546) is bolted to the inner wall of the protective shell (3) through the mounting rod.

6. A turbine auxiliary structure with a main shaft crack self-inspection function according to claim 5, characterized in that: The radial displacement sensor (536) is an eddy current sensor, and the distance between its detection end and the driven wedge (535) is 0.5-1mm. The axial force sensor (546) is a strain gauge force sensor, and its measurement range is 0-500N.

7. The turbine auxiliary structure with self-inspection function for main shaft cracks according to claim 1, characterized in that: The elastic support (4) includes several sets of spring dampers distributed circumferentially along the inner side of the annular bracket (2). Each set of spring dampers includes an outer sleeve (41) and an inner slide rod (42). The outer sleeve (41) is rotatably connected to the annular bracket (2). One end of the inner slide rod (42) is rotatably connected to the protective shell (3), and the other end extends into the outer sleeve (41) and is slidably connected to the outer sleeve (41). A movable plate (43) is bolted to one end of the inner slide rod (42) that extends into the outer sleeve (41). Buffer springs (44) are provided between the movable plate (43) and the inner wall of the outer sleeve (41) and on the surface of the inner slide rod (42).

8. A turbine auxiliary structure with a main shaft crack self-inspection function according to claim 7, characterized in that: The outer sleeve (41) is filled with oil, and one end of the outer sleeve (41) and the inner slide rod (42) are rotatably connected to a rotating frame (9). The outer sleeve (41) and the inner slide rod (42) are rotatably connected to the annular bracket (2) and the protective shell (3) respectively through the rotating frame (9).

9. A turbine auxiliary structure with a main shaft crack self-inspection function according to claim 1, characterized in that: The crack detection structure (5) further includes a signal processing module, which includes: The signal acquisition unit is used to receive the voltage signal output by the radial displacement sensor (536) and the current signal output by the axial force sensor (546); The feature extraction unit is used to perform time-domain analysis (extracting peak value and variance) and frequency-domain analysis (extracting second and third harmonic amplitude) on the acquired signal. The judgment unit has a preset crack judgment threshold. When the peak value of the radial displacement signal exceeds 0.1mm and the proportion of the second harmonic amplitude exceeds 15%, or the fluctuation of the axial force signal exceeds 50N and the duration exceeds 5s, the turbine main shaft (1) is judged to have a crack.

10. A turbine auxiliary structure with a main shaft crack self-inspection function according to claim 1, characterized in that: The protective shell (3) is composed of two half shells, which are connected by bolts. The top and bottom of the two half shells are inlaid with sealing rings (10), and the inner side of the sealing rings (10) is in rotational contact with the turbine main shaft (1).

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