Stator stabilizing structure of hydraulic generator

Abstract

The invention discloses a hydro-generator stator stabilizing structure, which comprises a plurality of combined connecting units distributed along the circumferential direction of a stator core, and is characterized in that each combined connecting unit comprises an inner side connecting part embedded with an axial extending groove on the outer diameter side of the stator core, and an outer side connecting part embedded with an axial extending groove on the outer diameter side of the stator core; the outer side connecting part is inserted into a guide groove of a pull block fixed on the stator frame; a radial displacement compensation space is formed between the bottom of the guide groove of the pull block and the outer side connecting part; the two axial ends of the combined connection unit are provided with stop blocks in contact with the stator base, and the stop blocks are fixed through axial fasteners. By means of the combined constraint mode that axial segmented embedding of the combined connecting units is combined with radial guiding gaps, the problems of radial stress concentration and circumferential roundness instability caused by thermal deformation of the stator core of the large hydro-generator under the cold and hot alternating working condition are solved, and collaborative optimization of electromagnetic load stable transmission and structural service life is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of hydroturbine stator installation, and in particular to a stable structure for the stator of a hydrogenerator. Background Art

[0002] As a core equipment for converting water energy into electrical energy, the operating reliability of a hydrogenerator set directly affects the stability of the power system. The stator assembly, as the core structural component of the generator, is composed of components such as a stator frame, an iron core, and windings. Among them, the stator iron core is formed by laminating silicon steel sheets and is rigidly connected to the frame through positioning ribs to transmit electromagnetic force and torque. Under rated operating conditions, eddy current losses generated by the alternating magnetic field inside the iron core and power losses generated by winding current will cause the temperature of the stator iron core to rise, which will in turn cause thermal expansion. The existing designs generally adopt a fully constrained connection method. Although it can effectively control the vibration of the iron core, the problem of thermal stress accumulation is becoming increasingly prominent. In severe cases, it may even cause the stator iron core to become unstable.

[0003] In recent years, with the continuous increase in the single-unit capacity of hydrogenerators, the thermal deformation of the stator iron core has become more prominent: when the temperature of the iron core approaches the limit temperature, its radial expansion cannot be ignored. At this time, the asymmetric support characteristics of the frame ring plate structure will cause local stress concentration. The traditional design suppresses deformation by increasing the structural stiffness, but it instead exacerbates the radial extrusion between the iron core and the frame, forming a vicious cycle of "rigid constraint - thermal stress accumulation - structural instability", resulting in an increase in mechanical vibration and noise during the operation of the unit, which will shorten the service life of the equipment.

[0004] Therefore, in response to the above problems, some solutions have been proposed in the industry. For example, "A Hydroturbine Stator Frame" disclosed in the Chinese patent literature, with the publication number "CN112350484B", includes a seat ring, several frame legs, and an upper frame. The seat ring is in a circular ring shape, and several frame legs are evenly distributed along the circumference of the seat ring and fixedly connected to the seat ring. One end of the frame leg is located above the seat ring and is provided with a support block, and a self-locking mechanism is provided on the support block. The support block is detachably connected to the upper frame through the self-locking mechanism. The other end of the frame leg is located below the seat ring.

[0005] In the above solution, rapid positioning and automatic locking of the upper frame are achieved, the connection is precise, and no manual operation is required; at the same time, it is convenient to disassemble, saving time and effort. However, this solution still does not solve the fundamental contradiction between the constraint method and the thermal deformation release path, and it is difficult to meet the long-term stable operation requirements of large-capacity units. Summary of the Invention

[0006] In view of the fundamental contradiction between the stator constraint method and the thermal deformation release path mentioned above, the present invention provides a stator stability structure for a hydrogenerator, which solves the problems of radial stress concentration and circumferential roundness instability caused by thermal deformation of the stator core of a large hydrogenerator under cold and hot alternating conditions through a combined constraint form of axial segmented fitting of the combined connection unit and radial guiding clearance, and realizes the collaborative optimization of stable electromagnetic load transfer and structural life.

[0007] To achieve the above object, the present invention adopts the following technical solutions: A stator stability structure for a hydrogenerator, comprising: a plurality of combined connection units distributed circumferentially along the stator core, the combined connection unit comprising: an inner connection part, which is fitted into an axially extending groove on the outer diameter side of the stator core; an outer connection part, which is inserted and fixed into a guiding groove of a pull block on the stator frame; a radial displacement compensation space is formed between the bottom of the guiding groove of the pull block and the outer connection part; the combined connection unit is provided with a stop block in contact with the stator frame, and the stop block is fixed by a fastener.

[0008] The stator stability structure includes a plurality of combined connection units circumferentially distributed on the outer diameter of the stator core. The inner side of each unit is fitted and connected with the stator core through an axially extending groove, and the outer side is inserted and fixed into the guiding groove of the pull block on the frame. A radial gap is reserved between the bottom of the guiding groove of the pull block and the outer connection part to form a thermal expansion displacement compensation space. Stop blocks are arranged at both axial ends of the combined unit and are abutted against the frame through fasteners. This structure effectively absorbs thermal expansion deformation and inhibits core instability through the synergistic effect of gap compensation and axial limitation.

[0009] Preferably, the inner connection part adopts a symmetric inclined surface fitting structure, and the outer connection part is provided with a shoulder guiding structure extending transversely. The two are detachably connected by an axial screw. The inclined surface fitting structure enhances the radial load-bearing capacity, the shoulder guiding structure ensures the circumferential positioning accuracy, and the screw connection method is convenient for local replacement during maintenance.

[0010] Preferably, the inner wall of the guiding groove of the pull block is axially machined with a spiral guiding groove, and the pitch of the spiral guiding groove increases along the groove depth direction. The spiral structure converts the linear displacement into a rotational component, and disperses the local stress concentration through progressive guiding to avoid the impact of sudden loads on the guiding groove.

[0011] Preferably, the spiral direction of the guiding groove is opposite to the circumferential displacement direction generated by the thermal expansion of the core. This design generates a reverse torsion effect, offsets the accumulation of circumferential displacement, and reduces the circumferential shear stress.

[0012] Preferably, the contact surface between the outer connection part and the guiding groove adopts a double-curvature fitting design, and the axial curvature radius is greater than the circumferential curvature radius. The double-curved surface forms a dynamically self-adjusting contact area, and the contact point slides along the curved surface at high temperature, reducing the peak contact stress.

[0013] Preferably, the line connecting the centers of curvature of the double-curved surfaces corresponds to the position of the radial stiffeners of the machine base. This spatial layout ensures deformation coordination and enables the thermal expansion displacement to be released along the path with the optimal structural stiffness.

[0014] Preferably, the inclined surface fitting structure is axially divided into multiple independent units, and expansion gaps are provided between the segments. The segmented structure allows for free axial expansion and eliminates the additional stress caused by overall bending deformation.

[0015] Preferably, the axial screw installation axis is alternately inclined with respect to the radial symmetry plane. The staggered inclined layout forms a multi-directional pre-tightening force field, enhancing the anti-shear performance of the connection interface and preventing connection loosening caused by high-frequency vibration.

[0016] Preferably, a circumferential arc-shaped recess is machined at the bottom of the guide groove of the pulling block, and its depth is less than the shoulder height of the outer connecting part. The recess provides an initial displacement buffer space to avoid rigid collisions during minor thermal expansion.

[0017] Preferably, the contact surface between the stop block and the stator frame adopts a stepped concave-convex fitting structure. The stepped surface forms a multi-stage limiting mechanism to release the axial thermal expansion amount in stages and prevent sudden displacement impacts.

[0018] Therefore, the present invention has the following beneficial effects: The combined connection unit adopts a two-way fitting structure in combination with the reserved radial gap. The electromagnetic force is stably borne through the inner inclined surface fitting, and the thermal expansion displacement can be released through the gap of the outer guide groove, effectively reducing the radial extrusion force between the iron core and the frame and suppressing deformation of the iron core.

[0019] By adding a guiding groove and a double-curved contact surface structure, the linear thermal expansion is converted into a helical displacement component and the contact area is dynamically adjusted to disperse the local stress peak and avoid jamming failure of the guiding structure at high temperatures.

[0020] The axial displacement is restricted by using a stepped stop block. Rigid impacts are avoided in the initial buffering stage, and the subsequent stepped limiting maintains the axial positioning accuracy to ensure the safe continuous operation of the unit. Description of the Drawings

[0021] Figure 1 It is a cross-sectional view of the present invention.

[0022] Figure 2 It is Figure 1 a partial enlarged view at A in

[0023] Figure 3 a cross-sectional view of the combined connection unit in Embodiment 1.

[0024] Figure 4 a cross-sectional view of the combined connection unit in Embodiment 2.

[0025] Figure 5 It is a schematic structural diagram of the contact surface in Embodiment 2.

[0026] In the figure: 1 - combined connection unit, 2 - dovetail rib, 3 - T-shaped rib, 31 - contact surface, 32 - highest point, 33 - radian, 4 - screw, 5 - pull block, 51 - relief cavity, 52 - guiding groove, 6 - stop block, 7 - bolt, 8 - gasket, 9 - stator core, 10 - stator frame. Specific implementation manners

[0027] The present invention will be further described below in conjunction with the accompanying drawings and specific implementation manners. Examples of the embodiments are shown in the drawings, where the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions throughout.

[0028] Embodiment 1 As Figure 1 , 2 shown, in this embodiment, the core of the stator stable structure lies in the two-way non-welding connection structure of the combined connection unit 1 to achieve the function of self-adaptive adjustment of thermal deformation. The dovetail rib 2 is adopted for the inner inclined surface fitting structure in the combined connection unit 1, and the T-shaped rib 3 is adopted for the outer shoulder guiding structure. The dovetail rib 2 and the T-shaped rib 3 are fixedly connected into an integral body by axially distributed threaded connectors. The symmetric inclined surfaces of the dovetail rib 2 are embedded in the axially extending grooves on the outer diameter side of the stator core 9 at a specific inclination angle to form a radial constraint interface; the transverse extending shoulders of the T-shaped rib 3 are inserted into the guiding grooves of the pull block 5, and the shoulder width thereof forms a clearance fit with the groove body. The pull block 5 is fixedly welded to the stator frame 10, and the radial clearance reserved between the bottom of its guiding groove and the shoulders of the T-shaped rib 3 of the combined connection unit 1 forms a thermal expansion displacement compensation space. The axial section of this clearance presents a wedge-shaped structure that gradually tapers from the inlet end to the bottom. The relief cavity 51 formed by the wedge-shaped structure and the T-shaped rib can provide a deformation space when the T-shaped rib expands due to heat, avoiding hard extrusion on the pull block; in this embodiment, the stator core is a cylindrical structure, and the stator frame is a multi-layer ring plate structure.

[0029] Specifically, the width of the transverse shoulder of the T-shaped rib 3 is slightly smaller than the opening size of the T-shaped groove of the pull block 5 to ensure smooth insertion and formation of a clearance fit during assembly. The pull block 5 is fixedly welded to the stator frame 10, and a uniform radial clearance is reserved between the bottom of its T-shaped groove and the shoulders of the T-shaped rib 3 of the combined connection unit 1. The axial section of this clearance is rectangularly distributed, and the clearance amounts at the inlet end and the bottom are the same, forming an equidistant buffer space.

[0030] The installation method with the combined connection units 1 evenly distributed along the circumference ensures the uniform transfer of circumferential loads. The inclined contact surface between the dovetail ribs 2 and the dovetail grooves of the stator core 9 is processed by precision machining, and the surface roughness of the contact area is controlled below Ra1.6 to reduce the frictional resistance under cold conditions. The mating surfaces of the T-shaped ribs 3 and the T-shaped grooves of the pull blocks 5 are hardened to enhance the resistance to fretting wear. The stop blocks 6 are fixed to the axial ends of the combined connection units 1 through bolts 7 and gaskets 8. Their contact surfaces are machined into plane structures, forming surface contacts with the stator frame 10. The contact pressure is precisely adjusted by controlling the pre-tightening force of the bolts 7 with a torque wrench.

[0031] When the unit is in the cold start-up stage, the stator core 9 mainly bears the electromagnetic force pointing towards the inner diameter. At this time, the mating surface between the inclined surfaces of the dovetail ribs 2 and the dovetail grooves transfers the load through the shoulders of the T-shaped ribs 3 to the pull blocks 5, and then disperses it to the frame through the welding points. Since the radial clearance is not compressed at this time, the combined connection units 1 are in a free state, and their structural stiffness is jointly determined by the sectional flexural stiffness of the dovetail ribs 2 and the T-shaped ribs 3. As the operating temperature rises, the stator core 9 generates a thermal expansion displacement towards the outer diameter, first consuming the radial clearance space between the shoulders of the T-shaped ribs 3 and the bottom of the grooves of the pull blocks 5. In this stage, the thermal deformation energy is partially absorbed by the elastic bending deformation of the combined connection units 1. When the expansion amount exceeds the clearance threshold, the shoulders of the T-shaped ribs 3 contact the bottom of the grooves. At this time, the load transfer path changes to the direct contact mode between the combined connection units 1 and the pull blocks 5, and the vibration energy is dissipated through the frictional damping of the contact surfaces. Through the synergistic effect of the mechanical fit clearance and the elastic deformation, the adaptive adjustment of the thermal expansion displacement is achieved while maintaining the structural load-bearing capacity.

[0032] In production practice, special fixtures are required for the machining of the combined connection units 1 to ensure the axial alignment of the dovetail ribs 2 and the T-shaped ribs 3. A laser locator is used during assembly to calibrate the circumferential distribution uniformity. The welding operation of the pull blocks 5 is carried out under the protection of inert gas, and the segmented skip welding process is adopted to control the welding deformation. After welding, ultrasonic flaw detection is required to detect internal defects. During the commissioning stage after installation, the operating temperature distribution is monitored with a thermal imager to ensure the thermal deformation coordination of each combined connection unit 1.

[0033] The dynamic implementation process and operation regulation of the embodiments of the present invention can be achieved through the following operation process: During installation, first pre-assemble the dove-tail rib 2 with the dovetail groove on the outer diameter side of the stator core 9, and adjust the circumferential distribution uniformity through a special tooling to ensure that the initial fitting states of all combined connection units 1 are the same. Subsequently, connect the T-shaped rib 3 and the dove-tail rib 2 through the axial screw 4, and the tightening sequence of the screw 4 follows the principle of alternately tightening from the center to both ends, and the torque value is increased in stages to eliminate the friction difference of the thread pair. When the whole combined connection unit 1 is hoisted onto the stator frame 10, the shoulder of the T-shaped rib 3 should contact and be tightened with the guiding groove of the pulling block 5 to ensure the radial clearance between the two. The welding of the pulling block 5 adopts the symmetric segmented skip welding process, controlling the interlayer temperature and supplemented by stress relief treatment. Before installing the stop block 6, it is necessary to detect the flatness of the contact surface of the frame, and the local sunken area is compensated by 8 groups of adjustable gaskets. The pre-tightening force of the bolt 7 is applied in a gradient manner and a margin for stress relaxation adjustment is reserved.

[0034] As Figure 3 shown, in this embodiment, during the cold start stage of the unit, the stator core 9 generates a radial load pointing to the inner diameter under the action of electromagnetic force. At this time, the contact between the inclined surface of the dove-tail rib 2 and the dovetail groove forms a rigid force transmission path and transmits the load to the frame. During this stage, the radial clearance between the combined connection unit 1 and the pulling block 5 is in an open state, and the overall stiffness of the structure is dominated by the sectional bending resistance of the dove-tail rib 2 and the T-shaped rib 3, ensuring the instantaneity and stability of torque transmission under cold conditions.

[0035] As the unit continues to operate, the thermal expansion effect caused by the temperature gradient of the stator core 9 gradually appears. The radial displacement generated by the thermal expansion of the core material first acts on the combined connection unit 1, and the reserved clearance between the shoulder of the T-shaped rib 3 and the bottom of the guiding groove of the pulling block 5 provides a free compensation space for the thermal deformation at this stage. This clearance enables the displacement absorption to be achieved only by overcoming the elastic deformation of the combined connection unit 1 itself at the initial stage of thermal expansion, avoiding premature triggering of rigid constraints. When the thermal expansion amount exceeds the clearance threshold, the shoulder of the T-shaped rib 3 and the bottom of the guiding groove enter the contact state. At this time, the friction coefficient and surface roughness of the contact surface 31 jointly determine the load transfer ratio, and part of the thermal stress is dissipated through the microscopic slip of the contact interface, and the remaining load is diffused to the frame through the welding points of the pulling block 5. This two-stage action mechanism not only ensures the continuity of torque transmission under thermal conditions, but also controls the radial extrusion force between the core and the frame within the safety threshold through the synergistic action of clearance buffering and friction energy dissipation.

[0036] During operation, the parallel contact surface between the combined connection unit 1 and the guiding groove of the pulling block 5 forms a geometric constraint on the circumferential displacement of the iron core, guiding the complex deformation caused by thermal expansion into a pure radial motion mode. This directional constraint mechanism effectively suppresses the circumferential displacement component, ensuring that the roundness deviation of the iron core always remains within the allowable range. The gap between the stop block 6 and the stator frame 10 is used to accommodate the thermal expansion and mechanical deformation generated by both in the axial space during operation, allowing the axial thermal expansion to be released in stages and preventing structural instability caused by sudden displacement impacts.

[0037] Practical engineering applications show that the new structure of this embodiment exhibits significant advantages in dealing with rapid variable operating conditions. When the load of the unit suddenly changes, resulting in a sharp change in the temperature of the stator iron core relative to the stator frame, the elastic deformation ability of the combined connection unit 1 and the reserved gap between the shoulder of the T-shaped rib 3 and the bottom of the guiding groove of the pulling block 5 can instantaneously respond to the thermal expansion change, avoiding stress concentration caused by rigid contact and structural instability of the stator iron core.

[0038] Embodiment 2 In this embodiment, the inner connection part of the combined connection unit 1 presents a symmetrical inclined surface structure, and its inclination angle forms a complementary relationship with the geometric profile of the axially extending groove on the outer diameter side of the stator iron core 9. The two inclined surfaces are embedded inside the groove in a mirror-symmetrical manner to form a self-locking mechanical connection. The outer connection part is provided with a shoulder structure extending transversely, and the width of this shoulder is slightly smaller than the opening size of the guiding groove of the pulling block 5, so that it can slide into the groove axially during assembly. Uniform radial gaps are reserved between the upper and lower surfaces of the shoulder and the inner wall of the guiding groove. The pulling block 5 is fixed to the frame by welding, and an arc-shaped recessed area extending circumferentially is machined at the bottom of its guiding groove, and the depth of the recess is less than the height of the shoulder of the outer connection part, forming an initial displacement buffer space.

[0039] As Figure 4 、 5As shown in the figure, a guiding groove 52 with a continuous spiral shape is arranged on the inner wall of the guiding groove. The spiral structure starts from the entrance of the groove body and gradually increases the pitch along the axial direction during the extension towards the bottom. The spiral direction is opposite to the circumferential displacement direction naturally generated when the iron core expands due to heat. The contact surface 31 between the shoulder of the outer connecting part and the guiding groove adopts a unique double-curved surface, specifically, a saddle-shaped hyperboloid: the radius of curvature in the axial direction is larger, forming a smooth sliding track; the radius of curvature in the circumferential direction is smaller, playing a role in restricting lateral movement. The connecting line of the geometric centers of the double-curved surfaces is spatially corresponding to the arrangement position of the radial stiffeners of the machine base, ensuring a reasonable match between the load transfer path and the structural stiffness. When the stator temperature rises, the contact first occurs at the highest point 32 of the saddle-shaped hyperboloid. At this time, the contact area is small, but the initial pressure can ensure the structural stability. When the temperature rises: the thermal expansion forces the contact point to slide down along the gentle front and back arcs. During the sliding process, the curved left and right arcs 33 are like two guardrails to prevent left and right offsets; until the stable state: the contact point finally stops at the "safety nests" (i.e., low-stress areas) on both sides of the saddle-shaped hyperboloid. At this position, the contact area increases and the pressure naturally decreases. In the flat-bottomed T-shaped groove used in Embodiment 1, during cold-state assembly, it seems that the whole plane is in contact. In fact, due to processing errors, the actual contact area is usually only 30-50% of the theoretical value. When the temperature rises, the axial expansion causes the contact surface to be misaligned, and the circumferential expansion causes edge warping. The actual contact area may shrink to line contact, and the local stress suddenly increases by 2-3 times; therefore, the saddle-shaped hyperboloid contact area proposed in this embodiment can effectively change from "passively bearing" to "actively adapting" - not preventing thermal expansion, but guiding the expansion energy to be released in a favorable direction, allowing the structure to automatically find the optimal load-bearing position during thermal deformation.

[0040] As Figure 4 shown in the figure, in this embodiment, the inclined surface fitting structure is axially divided into several independent units on the inner connecting part, and an equal-distance expansion gap is reserved between each unit. The gap size is calculated and determined according to the thermal expansion characteristics of the material. In this embodiment, the screw 4 is pre-installed in the T-shaped rib, and the installation axis of the connecting screw 4 is not vertically arranged, but the axes of adjacent screws 4 are alternately deflected by a specific angle to the left and right sides, forming a pre-tightening force distribution pattern that is staggered front and back. The contact surface between the stop block 6 and the machine base is processed into a multi-level stepped concave-convex structure, and the step height difference corresponds to the expected axial thermal expansion magnitude. The bearing area of each step is designed differently according to the estimated load level.

[0041] When the unit is in cold-state operation, the cooperation between the inclined surface fitting structure and the axially extending groove transfers the electromagnetic force to the pull block 5 component through the shoulder structure. At this time, the guiding groove and the double-curved contact surface have not yet entered the working state, and the radial reserved gap is in an open state. As the temperature rises, causing the iron core to expand, the outer connecting part generates a radial displacement along the guiding groove. The spiral structure of the guiding groove converts the linear movement into a circumferential rotation component, driving the bottom contact surface to slide along the double-curved track. During this process, the contact area is automatically adjusted to improve the stress distribution state. The gentle curvature of the double-curved surface in the axial direction ensures the smoothness of the sliding, while the tight curvature in the circumferential direction effectively controls the lateral offset amplitude.

[0042] When the segmented inner connecting unit expands thermally in the axial direction, each independent segment freely extends within the reserved gap range, avoiding bending deformation of the overall structure due to temperature difference. The alternately inclined screws 4 layout forms an interlocking effect in the circumferential direction, significantly reducing the risk of connection loosening under vibration conditions. The stepped contact surface of the stop block 6 forms multi-level limits in the axial direction, allowing the axial thermal expansion to be released in stages and preventing structural instability caused by sudden displacement impacts. When the axial displacement is small, the load is mainly borne by the contact surface of the lower step; when the displacement increases, the contact surfaces of higher steps gradually participate in bearing, forming a progressive displacement control mechanism.

[0043] During the actual assembly process, the machining of the guiding groove needs to ensure the continuity of the pitch change, usually achieved by using the involute programming of a numerical control machine tool for smooth transition. The forming of the double-curved contact surface depends on precision grinding technology, and the surface needs to be nitrided to improve wear resistance. The cutting position of the segmented inner connecting unit needs to avoid high-stress areas, usually selected to be segmented in the middle position between adjacent stiffeners. When installing the inclined screws 4, an angle positioning fixture is required to ensure that the inclined directions of adjacent screws 4 are strictly symmetrical.

[0044] This solution performs well under thermal cycling conditions. The reverse spiral direction of the guiding groove forces the thermal expansion displacement to generate a reverse torsional component, effectively offsetting the circumferential shear stress; the adaptive sliding characteristics of the double-curved contact surface avoid local stress concentration and extend the service life of the contact surface; the segmented structure cooperates with the inclined screws 4 layout to achieve multi-dimensional thermal deformation compensation while maintaining the connection stiffness.

[0045] The dynamic operation process of the embodiment of the present invention can be specifically demonstrated through the actual operation process: During installation, first, the segmented inclined surface fitting unit is gradually installed into the axial groove on the outer diameter of the stator core 9. The operator uses a laser alignment instrument to adjust the axial alignment of each segment to ensure that the expansion gaps between adjacent segments are evenly distributed. Subsequently, the shoulder structure with the double-curved contact surface is inserted into the guiding groove of the pull block 5, and the starting orientation of the guiding groove is adjusted with the help of a positioning tooling to make its spiral direction accurately correspond to the circumferential displacement trend when the iron core expands thermally.

[0046] In the initial stage of the cold start of the unit, the electromagnetic force is smoothly transmitted to the shoulder structure through the bilateral inclined surfaces of the inclined surface fitting unit. At this time, the double-curved contact surface is in a free-sliding state, and the guiding groove has not yet participated in the load transfer. As the core temperature gradually rises, the thermal expansion pushes the shoulder to move outward along the guiding groove, and the reverse spiral structure of the guiding groove begins to take effect - when the shoulder slides radially along the groove body, the inclined surface of the guiding groove forces the shoulder to generate a circumferential micro-rotation opposite to the direction of thermal expansion. This ingenious motion conversion mechanism transforms the traditional unidirectional extrusion into a compound motion of spiral propulsion and rotational buffering, effectively decomposing the circumferential shear stress. At the same time, the special geometric shape of the double-curved contact surface guides the shoulder to automatically adjust the contact area during the sliding process: the gentle curvature in the axial direction allows smooth sliding, while the tight curvature in the circumferential direction forms a lateral constraint, thus precisely controlling the motion trajectory.

[0047] During operation, when the core expands axially due to heat, each independent section freely expands within the reserved gap, avoiding the additional stress caused by the bending of the overall structure. The alternately inclined screw 4 layout generates a dynamic self-tightening effect during the vibration of the unit - the vibration energy is converted into a small displacement between the screw head and the connecting surface, instead enhancing the biting tightness of the thread pair. The concave-convex contact surface of the stepped stop block 6 is like a multi-stage shock absorber: during the initial thermal expansion, the low-step contact surface absorbs the small displacement through elastic deformation; when the axial displacement increases, the high-step contact surface gradually participates in the load bearing, forming a progressive constraint.

[0048] Maintenance personnel regularly check the wear pattern of the working surface of the guiding groove. If it is found that the inner wall of the groove shows unilateral polishing, it indicates that the circumferential load distribution needs to be recalibrated. In actual operation, the force symmetry can be adjusted by rotating the installation phase of the combined connection unit 1. Thus, while effectively releasing the internal stress generated by the pull block after heating through the guiding groove structure, a load distribution monitoring index is also added.

[0049] In response to rapid load changes, this structure exhibits excellent performance. When the sudden change in the unit load causes a sudden change in the core temperature, the gradually changing pitch design of the guiding groove automatically adapts to different expansion rates - the small pitch section finely controls the slow expansion, and the large pitch section efficiently guides the rapid displacement. For the unit adopting this structure, the circumferential roundness deviation of the core is significantly reduced under the full load condition, and the replacement cycle of the key connecting components is extended.

[0050] Embodiment 3 Compared with Embodiment 1, in this embodiment, designers can make adaptive improvements to key components according to actual working conditions. When using a unilateral wedge structure to replace the original symmetrically arranged inclined surface fitting structure, an adjustable tightening device is additionally arranged on the opposite side of the wedge surface. This device consists of an adjusting bolt loaded by a spring. By screwing the bolt, the spring preload is changed to maintain the pressure balance of the contact surface. The guide groove structure can be changed to an I-shaped cross-section design. At this time, the shoulder of the combined connection unit 1 needs to be machined into a shape with a lateral flange accordingly. An appropriate gap is reserved between the flange and the side wall of the I-shaped groove to ensure smooth assembly and limit lateral offset.

[0051] The elastic damping layer added at the bottom of the guide groove is usually made of carbon fiber reinforced composite material. Its thickness is gradually distributed along the depth direction of the groove body. The entrance end is thinner to reduce the sliding resistance, and the bottom area is thickened to improve the bearing capacity. This damping layer is fixed to the bottom of the groove through a high-temperature bonding process, and micron-level textures are processed on the surface to enhance the friction damping effect. For units with frequent fluctuations in electromagnetic load, a copper-aluminum composite transition gasket is embedded between the wedge surface and the dovetail groove. The soft aluminum base layer can undergo plastic deformation to absorb energy during sudden impacts, and the hard copper surface layer ensures the current conduction efficiency under normal conditions.

[0052] During actual application, a certain adjustment margin is reserved for the adjusting bolt of the unilateral wedge structure during cold assembly to cope with contact surface wear during operation. The lateral flange gap of the I-shaped guide groove is regularly checked. When the gap increases by more than 30% of the design value, adjustment gaskets need to be added.

Claims

1. A stator stability structure for a hydrogenerator, characterized in that, Comprising: A plurality of combined connection units circumferentially distributed along the stator core (9), and each of the combined connection units includes: An inner connection portion which is fitted into an axially extending groove on the outer diameter side of the stator core (9); An outer connection portion which is inserted and fixed into a guiding groove of a pulling block (5) on the stator frame (10); A radial displacement compensation space is formed between the bottom of the guiding groove of the pulling block (5) and the outer connection portion; Stop blocks (6) contacting the stator frame (10) are provided at both axial ends of the combined connection unit, and the stop blocks (6) are fixed by axial fasteners.

2. The stator stability structure of a hydro-generator according to claim 1, wherein: The inner connection portion includes symmetrically arranged bevel fitting structures (2), the outer connection portion includes a shoulder guiding structure (3) extending transversely, and the bevel fitting structures (2) and the shoulder guiding structure (3) are connected by axially arranged screws (4).

3. The stator stability structure of a hydro-generator according to claim 1, wherein: The inner wall of the guiding groove of the pulling block (5) is provided with a guiding groove spirally extending axially, and the pitch of the guiding groove gradually increases from the inlet end to the bottom of the guiding groove.

4. The stator stability structure of a hydro-generator according to claim 3, wherein: The spiral direction of the guiding groove is opposite to the circumferential displacement direction generated when the stator core (9) thermally expands.

5. The stator stability structure of a hydro-generator according to any one of claims 1-4, wherein: The contact surface between the outer connection portion and the guiding groove is a double-curvature mating surface, and its axial radius of curvature is greater than the circumferential radius of curvature.

6. The stator stability structure of a hydro-generator according to claim 5, wherein: The connection line of the centers of curvature of the double-curvature mating surface corresponds to the position of the radial reinforcing rib of the stator frame (10).

7. The stator stability structure of a hydro-generator according to claim 2, wherein: The dovetail ribs (2) are axially divided into multiple independent units, and an axial expansion gap is formed between adjacent units.

8. The stator stability structure of a hydro-generator according to claim 2, wherein: The axis of the screw (4) is alternately inclined to both sides with respect to the radial symmetry plane of the combined connection unit.

9. The stator stability structure of a hydro-generator according to claim 1, wherein: The bottom of the guiding groove of the pulling block (5) is provided with an arc-shaped recess extending circumferentially, and the depth of the recess is less than the shoulder height of the outer connection portion.

10. The stator stability structure of a hydro-generator according to claim 1, wherein: The contact surface between the stop block (6) and the stator frame (10) is a stepped concave-convex mating structure.

Images