Rear sealing anti-loosening structure of gas compressor casing

Abstract

The invention relates to the technical field of aero-engine structures, in particular to a gas compressor casing rear sealing anti-loosening structure which comprises a plurality of studs penetrating through through holes in the axial end face of a lining to be connected with threaded holes. A boss is arranged on the stud and located between the lining and the casing. The diameter of the boss is larger than that of the stud and smaller than that of the through hole. And the nut is connected to the stud and is pressed on one side, far away from the casing, of the rear sealing cover. An annular locking piece is arranged between the nut and the rear sealing cover, locking holes corresponding to the studs in a one-to-one mode are formed in the annular face of the locking piece, a locking piece is arranged on the outer side of each locking hole, and a certain side edge rib of the nut is matched with the corresponding locking piece. According to the compressor casing rear sealing anti-loosening structure, the locking performance is improved by improving the locking plate structure, the boss is additionally arranged on the stud to prevent fault deterioration, the connection reliability of the compressor rear sealing position is improved, the stud and the nut cannot touch a centrifugal impeller, and the serious fault that a rotor is stuck cannot occur.

Description

Technical Field

[0001] This invention relates to the field of aero-engine structural technology, specifically to a compressor casing rear seal anti-loosening structure. Background Technology

[0002] Currently, through disassembly, inspection, and statistical analysis of multiple faulty machines, the assembly status of parts at the source of the fault exhibits the same abnormalities: nuts falling off; locking plates falling off or failing (opening outwards or breaking); the end face of the bolt post being lower than the end face of the nut; bolt posts being loose, especially the bolt posts corresponding to the problematic nut locking plates being significantly loose; some loose bolt posts have protruded outwards, their end faces rubbing against the back of the centrifugal impeller, preventing the centrifugal impeller from rotating and causing rotor jamming.

[0003] After disassembly and troubleshooting, it was found that the compressor casing rear seal uses a locking plate pressed between the nut and the rear seal cover, and the locking plate is tongue-shaped (e.g., Figure 1 a) Each nut is paired with one locking plate, and the five locking plates are independent of each other. The locking plates are prevented from rotating by the mating of the arc surface R32 with the outer circular surface Φ61 on the sealing cap, and by the bending of the locking plates and their contact with one of the six planes on the side of the nut. The larger the clearance between R32 and Φ61, the easier it is for the locking plates to rotate; if the locking plates rotate, coupled with poor contact quality between the locking plates and the nut side during assembly, the nut is prone to rotation and loosening.

[0004] Secondly, due to quality issues such as machining and assembly, the threaded hole at the rear seal of the compressor casing is too large, resulting in insufficient thread tightness and unreliable connection.

[0005] In addition, considering the interchangeability of new and old parts, a wire thread insert is usually installed between the stud and the housing to improve the locking performance of the threaded connection. However, because the housing is made of cast magnesium—which is relatively soft—and the stud is made of steel—which is relatively hard—the internal threads on the housing are easily deformed when the device vibrates during operation, gradually losing their original tightness and loosening. More importantly, the wire thread insert has a fatal flaw due to the structure of the back seal: after the wire thread insert is inserted into the internal thread, its settlement must be controlled; during inspection and repair, it is permissible to remove and replace the wire thread insert. However, because the wire thread insert is pressed against a non-removable bushing, and the stud hole of the bushing is smaller than the outer diameter of the wire thread insert, although the wire thread insert can be installed first and then the bushing, if a problem occurs, the wire thread insert will not be able to pass through the bushing hole, making it impossible to adjust the settlement or remove and replace it.

[0006] Under long-term engine operation, rotor jamming failures frequently occur due to loosening and dislodging of bolts and nuts, and failure of locking plates. Summary of the Invention

[0007] To address the problems existing in the prior art, the present invention provides a compressor casing rear seal anti-loosening structure. The improved locking plate structure enhances the locking performance, and the addition of a boss on the stud prevents the stud from loosening and rubbing against the compressor rotor, thereby improving the connection reliability of the compressor rear seal.

[0008] This invention is achieved through the following technical solution: A compressor casing rear seal anti-loosening structure includes: The casing has multiple threaded holes at its large end. The bushing is interference-fitted into the large end of the casing; Multiple studs are provided, and the studs pass through the through holes and threaded holes on the axial end face of the bushing; a boss is provided on the stud, which is located between the bushing and the housing; the diameter of the boss is larger than the diameter of the stud but smaller than the diameter of the through hole. The nut is attached to the stud and pressed against the rear sealing cover on the side away from the casing.

[0009] Preferably, the stud and the threaded hole adopt a transitional fit.

[0010] Preferably, the range of the transition fit is -0.007 to 0.116 mm.

[0011] Preferably, the large end of the casing is provided with a countersunk hole coaxial with the threaded hole, the countersunk hole is located on the side of the threaded hole near the bushing, and the boss is located in the countersunk hole.

[0012] Preferably, the boss and the stud are integrally formed or detachably connected.

[0013] Preferably, an annular locking plate is provided between the nut and the rear sealing cap. The annular surface of the locking plate has locking holes that correspond one-to-one with the studs. A locking piece is provided on the outer side of the locking hole, and a certain side edge of the nut cooperates with the locking piece.

[0014] Preferably, the locking plate has a through groove, and the side edge of the nut is located in the through groove.

[0015] Preferably, the locking piece forms locking strips on both sides of the through groove, and the locking strips are attached to the side of the nut.

[0016] Preferably, the locking piece is made of flexible metal material, and is sheet-like when not installed, while the locking strip is raised and attached to the side of the nut when installed.

[0017] Preferably, the through hole of the bushing is not chamfered.

[0018] Compared with the prior art, the present invention has the following beneficial effects: The present invention discloses a compressor casing rear seal anti-loosening structure by adding a boss on the stud to prevent the stud from loosening and rubbing against the compressor rotor. A bushing is used to block the boss to prevent the stud from coming out and damaging the centrifugal impeller and jamming the rotor, thereby improving the connection reliability of the compressor rear seal.

[0019] Furthermore, the countersunk hole provides installation space for the boss, ensuring that the stud will not fall into the threaded hole of the casing, and also preventing the stud from coming out directly when the nut falls off.

[0020] Furthermore, the locking plate structure is improved by using the interlocking of all locking plates to enhance the locking performance. Specifically, a locking plate can lock the nut by engaging one of its side ribs. Each locking plate locks its corresponding nut. When a nut rotates, it will drive the corresponding locking plate to rotate, but because other locking plates are locked by other nuts, they cannot rotate freely. Therefore, the locking performance of the locking plates is enhanced.

[0021] Furthermore, the locking plate is in sheet form during installation to facilitate processing and transportation, and to ensure the performance of the locking plate.

[0022] Furthermore, removing the chamfer on the bushing through hole can enhance the bushing's fit and tightness against the bolt. Attached Figure Description

[0023] Figure 1 A schematic diagram of the existing locking plate and assembly; Figure 2 This is a structural diagram of the locking plate in the compressor casing rear seal anti-loosening structure of the present invention; Figure 3 This is an assembly structure diagram of the bolt structure in the compressor casing rear seal anti-loosening structure of the present invention; Figure 4 This is a structural diagram of the bolt structure showing the boss in the compressor casing rear seal anti-loosening structure of the present invention.

[0024] In the diagram, 1. Rear sealing cover; 2. Bushing; 3. Screw; 4. Locking plate; 41. Locking plate; 5. Nut; 6. Boss; 7. Casing. Detailed Implementation

[0025] The present invention will be further described in detail below with reference to specific embodiments. These descriptions are for explanation purposes only and are not intended to limit the scope of the invention.

[0026] This invention discloses a compressor casing rear seal anti-loosening structure, referring to... Figures 1-4 ,include: The housing 7 has multiple threaded holes at its large end; the bushing 2 is fitted into the large end of the housing 7 with an interference fit; the studs 3 are provided in multiple ways, and the studs 3 pass through the through holes on the axial end face of the bushing 2 and connect with the threaded holes; the studs 3 and the threaded holes adopt a transition fit, and the range of the transition fit is -0.007 to 0.116 mm.

[0027] A boss 6 is provided on the bolt 3, which is located between the bushing 2 and the housing 7. The diameter of the boss 6 is larger than the diameter of the bolt 3 but smaller than the diameter of the through hole. Even if the bolt hole is too large, the bolt 3 will not sink during installation due to the presence of the boss 6; even if the bolt 3 becomes loose, it will not protrude outward.

[0028] The large end of the casing 7 is provided with a countersunk hole coaxial with the threaded hole. The countersunk hole is located on the side of the threaded hole near the bushing 2, and the boss 6 is located in the countersunk hole. The boss 6 is integrally formed with the stud 3 or is detachably connected. The integrally formed type can ensure the integrity of the stud 3, while the detachable type can be replaced and repaired separately.

[0029] Nut 5 is attached to stud 3 and pressed against the rear sealing cover 1 on the side away from the casing 7.

[0030] A ring-shaped locking plate 4 is provided between the nut 5 and the rear sealing cover 1. The ring surface of the locking plate 4 has locking holes that correspond one-to-one with the screw post 3. A locking piece 41 is provided on the outside of the locking hole. One side edge of the nut 5 cooperates with the locking piece 41.

[0031] The locking piece 41 has a through groove, and the side edge of the nut 5 is located in the through groove. The locking piece 41 forms locking strips on both sides of the through groove, and the locking strips are attached to the side of the nut 5.

[0032] When not installed, the locking piece 41 is in the shape of a sheet. When installed, the locking strip is raised (a tool such as a screwdriver can be used) and attached to the side of the nut 5.

[0033] In one embodiment, the locking piece 41 is dovetail-shaped, referred to as an annular dovetail locking piece 4, which can mutually brake each other. When the bolt 3 is inserted, it ensures that the locking piece 4 itself does not rotate. Combined with the improved locking piece 4 dovetail mating with one of the six edges of the nut 5, the two tips of the dovetail clamp this edge in the middle, preventing the nut 5 from rotating. This is more reliable than the original structure that uses surface-to-surface mating to prevent the nut 5 from rotating, and can further improve the locking performance of the locking piece 4.

[0034] The through hole of bushing 2 is not chamfered, in order to strengthen the fit and tightness of bushing 2 with bolt 3.

[0035] The connection structure at the rear seal of a compressor includes a steel stud 3, a nut 5, a locking plate 4, and a bushing 2, as well as a magnesium compressor casing 7, the purpose of which is to fix the rear seal cover 1.

[0036] like Figure 3 As shown, the compressor casing 7 is flared, with the rear sealing cover 1 located at the large end. At the center of the large end are five AG8×1.25 internal threaded holes, each containing an AG8×1.25 bolt 3. The AG8 threads are fitted with d2(+0.116~+0.056) / D2(+0.063~0), resulting in a transitional fit of -0.007~0.116. The bolt 3 is secured by a slight interference fit and preload.

[0037] Bushing 2 is T-shaped and is interference-fitted into the center of the large end face of compressor casing 7. Screw 3 passes through five through holes on the axial end face of bushing 2. The inner hole of bushing 2 serves as the reference for other machined surfaces of compressor casing 7 and cannot be removed or replaced from casing 7; otherwise, the interference fit with casing 7 and the accuracy of other machined surface dimensions cannot be guaranteed. The outer side of bushing 2 is the rear sealing cover 1, and nut 5 is installed on screw 3 to secure the rear sealing cover 1.

[0038] An annular dovetail locking piece 4 is pressed between the nut 5 and the rear sealing cap 1, such as Figure 2 As shown. When the annular dovetail locking plate 4 is installed into the stud 3, the five dovetail locking plates 41 can brake each other. The dovetail of the locking plate 41 matches one of the six ridges of the nut 5. The two tips of the dovetail clamp the ridge in the middle, making the nut 5 unable to rotate. This is more reliable than the original structure (tongue-type locking plate 4) which uses face-to-face matching to prevent the nut 5 from rotating, thus improving the locking performance of the locking plate 4.

[0039] Because a boss 6 is added to the existing stud 3, such as Figure 4 As shown. The boss 6 is placed into the countersunk hole, and the stud 3 is inserted into the threaded hole. The bushing 2 is then pressed into the large end of the housing 7. The through hole Ф8.5 on the bushing 2 just blocks the annular Ф9 boss 6, preventing the stud 3 from being removed. (See diagram.) Figure 3 As shown. Combined with the annular dovetail locking piece 4, this connection can always maintain a good locking condition.

[0040] Finally, an assembly test was conducted. During the test run, the engine operated normally, all performance parameters were met, and no faults or abnormalities occurred. After the test run, the appearance of the rear seal, its looseness, the extension of bolt 3, and the sealing performance of compressor casing 7 were inspected. The machining and assembly were successfully completed, and the sealing test was also passed without any abnormalities. Bolt 3, nut 5, and locking plate 4 were properly tightened without any looseness. The extension of bolt 3 was normal, and the sealing test of compressor casing 7 was passed.

[0041] In summary, the compressor casing rear seal anti-loosening structure of the present invention improves the locking performance by improving the structure of the locking plate 4, adds a boss 6 on the screw post 3 to prevent the fault from worsening, and improves the connection reliability of the compressor rear seal. The screw post 3 and nut 5 will not be able to hit the centrifugal impeller, and serious faults such as rotor jamming will not occur.

[0042] The above description is merely a preferred embodiment of the present invention and is not intended to limit the technical solution of the present invention in any way. Those skilled in the art should understand that, without departing from the spirit and principles of the present invention, the technical solution can be modified and replaced in several simple ways, and these modifications and replacements are all within the scope of protection covered by the claims.

Claims

1. A compressor casing rear seal anti-loosening structure, characterized in that, include: The casing (7) has multiple threaded holes at its large end; Bushing (2) is fitted into the large end of housing (7) in an interference fit; Multiple screw posts (3) are provided. The screw posts (3) pass through the through holes and threaded holes on the axial end face of the bushing (2). A boss (6) is provided on the screw post (3). The boss (6) is located between the bushing (2) and the casing (7). The diameter of the boss (6) is larger than the diameter of the screw post (3) and smaller than the diameter of the through hole. Nut (5) is attached to stud (3) and pressed onto the rear sealing cover (1) on the side away from the casing (7).

2. The compressor casing rear seal anti-loosening structure according to claim 1, characterized in that, The stud (3) and the threaded hole adopt a transition type fit.

3. The compressor casing rear seal anti-loosening structure according to claim 2, characterized in that, The range of transition fit is -0.007 to 0.116 mm.

4. The compressor casing rear seal anti-loosening structure according to claim 1, characterized in that, The large end of the casing (7) is provided with a countersunk hole coaxial with the threaded hole. The countersunk hole is located on the side of the threaded hole close to the bushing (2), and the boss (6) is located in the countersunk hole.

5. The compressor casing rear seal anti-loosening structure according to claim 1, characterized in that, The boss (6) and the stud (3) are integrally formed or detachably connected.

6. The compressor casing rear seal anti-loosening structure according to claim 1, characterized in that, A ring-shaped locking plate (4) is provided between the nut (5) and the rear sealing cover (1). The ring surface of the locking plate (4) is provided with locking holes corresponding to the screw post (3). A locking plate (41) is provided on the outside of the locking hole. A certain side edge of the nut (5) cooperates with the locking plate (41).

7. The compressor casing rear seal anti-loosening structure according to claim 6, characterized in that, A through groove is provided on the locking piece (41), and the side edge of the nut (5) is located in the through groove.

8. The compressor casing rear seal anti-loosening structure according to claim 7, characterized in that, The locking piece (41) forms a locking strip on both sides of the through groove, and the locking strip is attached to the side of the nut (5).

9. The compressor casing rear seal anti-loosening structure according to claim 8, characterized in that, When the locking piece (41) is not installed, it is in the shape of a piece. When installed, the locking strip is raised and attached to the side of the nut (5).

10. The compressor casing rear seal anti-loosening structure according to claim 1, characterized in that, The through hole of the bushing (2) is not chamfered.

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