Turbine outer ring connecting structure and gas turbine engine

Abstract

The turbine outer ring connecting structure comprises a turbine outer ring which comprises a body part and an extension part, the body part is provided with a ring surface, and the extension part comprises a front mounting rib plate and a rear mounting rib plate which extend from the body part in the radial direction perpendicular to the ring surface and are adjacent in the axial direction; the middle-layer casing adopts three sections and comprises a front casing, a middle casing and a rear casing; wherein the front casing is detachably connected with a front mounting rib plate of the turbine outer ring, the rear casing is detachably connected with a rear mounting rib plate of the turbine outer ring, and the front casing, the middle casing and the rear casing are detachably connected, so that the front casing, the middle casing and the rear casing are mounted and pre-tightened in the axial direction of an engine, and axial clamping and clearance fit are formed between the turbine outer ring and the middle casing. According to the method, the problem of thermal deformation mismatch in the assembly structure is solved by reserving the assembly clearance and reasonably arranging the mounting pre-tightening force applying scheme, the problems of overhigh thermal mismatch stress, mounting pre-tightening force relaxation, vibration and collision and the like are avoided, the preparation and machining precision requirement of the turbine outer ring is lowered, the mounting stress level is improved, and the production efficiency is improved. And the installation pre-tightening force is prevented from loosening.

Description

Technical Field

[0001] The present invention relates to the field of aero-engines, in particular to the field of gas turbine engines, and more specifically to a turbine outer ring connection structure and a gas turbine engine. Background Art

[0002] Components of gas turbines often need to withstand extremely high temperatures. For example, the turbine outer ring, as a main stationary component of the gas turbine, bears a very high ambient temperature during service. Currently, turbine outer ring components are mainly prepared from superalloy materials. However, the strength and stiffness of superalloy materials will significantly decrease under high-temperature environments, thereby affecting the upper limit of the operating temperature of turbine outer ring components and ultimately restricting the improvement of the overall performance of gas turbine engines.

[0003] Using ceramic matrix composites (CMC) to replace superalloy materials for preparing gas turbine engine turbine outer ring components can give full play to the characteristics of CMC, such as low density, excellent high-temperature mechanical properties, and good thermal stability, improve the upper limit of the operating temperature of turbine outer ring components, and reduce the amount of relevant cooling gas, which plays an important role in significantly improving the overall efficiency of gas turbine engines and reducing pollution emissions.

[0004] However, the difference in thermal expansion coefficients between CMC and superalloy materials will cause significant thermal deformation mismatch problems inside the connection and installation structure between CMC turbine outer ring components and engine metal components during temperature changes, thereby affecting the safety and reliability of the components themselves and the connection structure. In addition, CMC outer ring components also have problems of difficult forming and poor dimensional accuracy.

[0005] Currently, there are mainly the following several solutions in this technical field:

[0006] For example, the existing document CN 115315567 A discloses an assembly structure solution for a double-installation ribbed turbine outer ring with connecting piece holes and a metal casing. Among them, the metal casing is divided into two parts, one part is composed of an outer load-bearing casing, and the other part is composed of a front middle casing. The installation pre-tightening force between components is provided by axially arranged bolts and nuts, and the axial installation pre-tightening force is applied to the outside of the front and rear installation rib plates.

[0007] According to the above-mentioned existing document, in order to solve the thermal deformation mismatch problem, a technical solution of leaving a gap during cold-state installation of the connection and installation structure between the turbine outer ring component and the engine metal component is adopted, but such a setting will cause problems of vibration and collision.

[0008] Again, the existing document CN112922679A discloses an assembly structure solution for a turbine outer ring and a metal casing, but the metal casing presents a one-piece structure.

[0009] For another example, the existing document US20180363507A1 also discloses an assembly structure solution for a turbine outer ring and a ring support structure. However, although the ring support structure has two annular flanges, it still presents a one-piece structure.

[0010] According to the above existing documents, the turbine outer ring member and the middle casing are connected in a face-to-face close contact manner. However, since it is difficult to machine the CMC material into a flat surface with high flatness, for the connection structure of the CMC turbine outer ring and the middle casing with face-to-face close contact, the design and manufacturing difficulty of manufacturing the CMC turbine outer ring member is large, the processing technology is complex, and the manufacturing cost is high.

[0011] As can be seen from the above, the above existing documents cannot effectively solve the current technical problems in this field, namely, the problems of thermal deformation mismatch inside the assembly structure, excessive thermal mismatch stress, relaxation of installation pre-tightening force, vibration and collision, etc., and the structure is complex, thereby increasing the difficulty of preparation, forming and processing.

[0012] Therefore, in view of the above, it has become an urgent technical problem to be solved how to design a turbine outer ring connection structure that can overcome the above technical defects. Summary of the Invention

[0013] The present invention is made precisely to solve the above technical problems. An object of the present invention is to provide a turbine outer ring connection structure, which can solve the problems of thermal deformation mismatch, excessive thermal mismatch stress, relaxation of installation pre-tightening force, vibration and collision, etc., and has a simple structure, low difficulty in preparation, forming and processing.

[0014] Another object of the present invention is to provide a gas turbine engine.

[0015] In order to achieve the above invention object, according to one aspect of the present invention, there is provided a turbine outer ring connection structure, including:

[0016] A turbine outer ring, the turbine outer ring includes a body portion and an extension portion, the body portion has a ring surface, and the extension portion includes a front mounting rib plate and a rear mounting rib plate that extend radially from the body portion perpendicular to the ring surface and are axially adjacent;

[0017] A middle casing, which adopts a three-section type, including a front casing, a middle casing and a rear casing;

[0018] Wherein, the front casing is detachably connected to the front mounting rib plate of the turbine outer ring, the rear casing is detachably connected to the rear mounting rib plate of the turbine outer ring, and the front casing, the middle casing and the rear casing are detachably connected, so as to be pre-tightened axially during engine installation, and form axial clamping and clearance fit between the turbine outer ring and the middle casing.

[0019] Preferably, in the above turbine outer ring connection structure, the turbine outer ring connection structure further includes a first connecting member and a second connecting member; the front casing and the rear casing respectively include a front mounting connecting member and a rear mounting connecting member; first mounting holes and second mounting holes are respectively formed on the front mounting rib and the rear mounting rib of the turbine outer ring; the front casing has a mounting through hole, the middle casing has a first through hole, a first blind hole and a second blind hole, and the rear casing has a second through hole; the front mounting connecting member sequentially passes through the first mounting hole of the turbine outer ring and the second blind hole of the middle casing so as to detachably connect the front casing and the front mounting rib of the turbine outer ring; the rear mounting connecting member sequentially passes through the second mounting hole of the turbine outer ring and the first blind hole of the middle casing so as to detachably connect the rear casing and the rear mounting rib of the turbine outer ring; the first connecting member sequentially passes through the second through hole of the rear casing, the first through hole of the middle casing and the mounting through hole of the front casing, and screws the second connecting member into the first connecting member and applies an installation pre-tightening force.

[0020] Preferably, in the above turbine outer ring connection structure, at least two first mounting holes are formed on the front mounting rib, only one of which is a circular through hole, and the rest are runway-shaped long holes, and at least two second mounting holes are also formed on the rear mounting rib, only one of which is a circular through hole, and the rest are runway-shaped long holes; and the circular through holes on different mounting ribs are located on the same circumferential section.

[0021] Preferably, in the above turbine outer ring connection structure, the front casing includes an upper section of the front casing and a lower section of the front casing; a lower edge ridge is axially and rearwardly provided at the lower end of the lower section of the front casing, and the lower edge ridge is close to the front side surface of the front mounting rib of the turbine outer ring in the installation state, so as to form an axial assembly gap; the upper section of the front casing has an upper inner fitting surface and a step surface, and the upper inner fitting surface and the step surface are respectively used as the axial and radial installation limit fitting surfaces between the front casing and the middle casing.

[0022] Preferably, in the above turbine outer ring connection structure, first cooling air holes are circumferentially distributed between the mounting through holes along the upper inner fitting surface.

[0023] Preferably, in the above turbine outer ring connection structure, the middle casing includes an upper section of the middle casing and a lower section of the middle casing; the lower section of the middle casing is hollow, an impact cover plate is connected to the lower surface of the lower section of the middle casing, and impact cooling holes are formed on the impact cover plate for impact cooling of the outer ring surface of the turbine outer ring.

[0024] Preferably, in the above turbine outer ring connection structure, the lower section of the intermediate casing includes an upper ring surface of the lower section of the intermediate casing, a front side surface of the lower section of the intermediate casing, and a rear side surface of the lower section of the intermediate casing; the upper section of the intermediate casing includes a lower ring surface of the upper section of the intermediate casing, a front side surface of the upper section of the intermediate casing, and a rear side surface of the upper section of the intermediate casing; the front side surface of the upper section of the intermediate casing and the lower ring surface of the upper section of the intermediate casing serve as the axial and radial limiting and fitting surfaces when the intermediate casing and the front casing are installed, and the rear side surface of the upper section of the intermediate casing and the upper ring surface of the lower section of the intermediate casing serve as the axial and radial limiting and fitting surfaces when the intermediate casing and the rear casing are installed.

[0025] Preferably, in the above turbine outer ring connection structure, at the lower end of the rear side surface of the lower section of the intermediate casing, a first contact convex rib is axially arranged backward, and the first contact convex rib is used to press against the inner surface of the rear mounting rib plate of the turbine outer ring in the installed state and apply a normal pressing force.

[0026] Preferably, in the above turbine outer ring connection structure, a first notch is formed on the first contact convex rib and serves as a cold air flow channel.

[0027] Preferably, in the above turbine outer ring connection structure, a sloping protrusion is formed between the upper ring surface of the lower section of the intermediate casing and the rear side surface of the upper section of the intermediate casing, and it has a lower cavity inside; a gas collecting groove is provided at a position corresponding to the sloping protrusion on the front side surface of the upper section of the intermediate casing and the rear side surface of the upper section of the intermediate casing, and a second cold air hole leading to the lower cavity is provided at the bottom of the gas collecting groove.

[0028] Preferably, in the above turbine outer ring connection structure, the rear casing includes an upper section of the rear casing and a lower section of the rear casing; a second contact convex rib is axially arranged forward at the lower part of the lower section of the rear casing, and the second contact convex rib is used to press against the outer surface of the rear mounting rib plate of the turbine outer ring in the installed state and apply a normal pressing force.

[0029] Preferably, in the above turbine outer ring connection structure, a second notch is formed on the second contact convex rib and serves as a cold air flow channel, and a first contact convex rib is axially arranged backward at the lower end of the rear side surface of the lower section of the intermediate casing of the intermediate casing, and a first notch is formed on the first contact convex rib, and the first notch and the second notch are staggered in the circumferential direction.

[0030] Preferably, in the above turbine outer ring connection structure, the upper section of the rear casing includes a horizontal section, the horizontal section has a front side surface of the horizontal section and a lower ring surface of the horizontal section, and the front side surface of the horizontal section and the lower ring surface of the horizontal section serve as the axial and radial limiting and fitting surfaces when the rear casing and the intermediate casing are installed.

[0031] Preferably, in the above turbine outer ring connection structure, the first connecting member is in a three - segment form, including a left cylindrical segment, a middle segment, and a right cylindrical segment, and the second connecting member is in a three - segment form, including a left cylindrical portion segment, a middle convex portion segment, and a right cylindrical portion segment.

[0032] Preferably, in the above turbine outer ring connection structure, the first connecting member is a nut and the second connecting member is a bolt.

[0033] Preferably, in the above turbine outer ring connection structure, the entire first connecting member is hollow and has a threaded through - hole extending axially in the middle; and the left cylindrical portion segment of the second connecting member is in the form of a screw rod, and in the installed state, the left cylindrical portion segment is engaged with the threaded through - hole of the first connecting member by thread fitting.

[0034] Preferably, in the above turbine outer ring connection structure, one side of the outer surface of the middle segment has a convex plane, and the convex plane is used for limiting and abutting against the adjacent surface of the rear casing.

[0035] Preferably, in the above turbine outer ring connection structure, the front mounting connecting member and the rear mounting connecting member are pin bolts and are respectively installed on the corresponding first mounting hole and the second mounting hole of the front casing and the rear casing by interference fit.

[0036] Preferably, in the above turbine outer ring connection structure, the material of the turbine outer ring is a ceramic matrix composite material, and the material of the middle casing is a superalloy material.

[0037] According to another aspect of the present invention, a gas turbine engine is provided, which includes the turbine outer ring connection structure of the present invention.

[0038] Due to having the above technical solutions, compared with the prior art, the core technology of the present invention lies in:

[0039] 1. By using a ceramic matrix composite material to replace a superalloy material for preparing the turbine outer ring component, the disadvantages of the superalloy material such as low upper limit of service temperature, large material density, and poor chemical stability are overcome.

[0040] 2. The connection and assembly of the turbine outer ring component and the middle casing are realized, and the problem of thermal deformation mismatch inside the assembly structure is alleviated, avoiding problems such as excessive thermal mismatch stress, relaxation of installation pre - tightening force, and vibration and collision, and significantly improving the safety and reliability of the connection structure.

[0041] 3. The structural form of the turbine outer ring and the middle casing assembly is simple, the preparation and forming and processing difficulties are small, and the disassembly and assembly between components are simple, the structure is compact, and the cooling scheme is reasonable.

[0042] In view of the above, compared with the prior art, the turbine outer ring connection structure according to the present invention adopts a three - section middle casing for assembling the double - installation - rib - plate - type turbine outer ring, realizing the assembly between the turbine outer ring and the middle casing. By reserving an assembly gap and reasonably setting the installation pre - tightening force application scheme, the problem of thermal deformation mismatch inside the assembly structure is solved, avoiding problems such as excessive thermal mismatch stress, relaxation of installation pre - tightening force, and vibration and collision. The positions for applying the installation pre - tightening force between the turbine outer ring and the middle casing are the inner and outer sides of the rear installation rib plate, which is beneficial to reducing the requirements for the preparation and processing accuracy of the turbine outer ring, improving the outer ring installation stress level, and preventing the relaxation of the installation pre - tightening force. In addition, the turbine outer ring connection structure of the present invention not only has a simple structure, significantly reducing the difficulty of preparing and forming and subtractive processing of the turbine outer ring, but also is easy to disassemble and assemble, has a compact structure, and is convenient for replacement. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] To better understand the above - mentioned and other objects, features, advantages and functions of the present invention, reference may be made to the preferred embodiments shown in the accompanying drawings. The same reference numerals in the drawings refer to the same components. Those skilled in the art should understand that the drawings are intended to schematically illustrate the preferred embodiments of the present invention and have no restrictive effect on the scope of the present invention. The components in the drawings are not drawn to scale. In the figures:

[0044] - Figure 1 Schematically shows a structural diagram of the turbine outer ring connection structure of a specific embodiment of the present invention;

[0045] - Figure 2 Schematically shows a structural diagram of the turbine outer ring of a specific embodiment of the present invention;

[0046] - Figure 3 Schematically shows a structural diagram of the front casing of the middle casing of a specific embodiment of the present invention;

[0047] - Figure 4 Schematically shows a structural diagram of the middle casing of the middle casing of a specific embodiment of the present invention;

[0048] - Figure 5 Schematically shows a structural diagram of the rear casing of the middle casing of a specific embodiment of the present invention;

[0049] - Figure 6 Schematically shows a structural diagram of the first connecting piece and the second connecting piece of a specific embodiment of the present invention;

[0050] - Figure 7 Schematically shows an assembly diagram of the turbine outer ring and the middle casing of a specific embodiment of the present invention;

[0051] - Figure 8Schematically shows the sectional position diagram of the installation state after the assembly of the turbine outer ring and the middle casing in a specific embodiment of the present invention;

[0052] - Figure 9 Schematically shows Figure 8 a sectional view taken along line I-I in

[0053] - Figure 10 Schematically shows Figure 8 a sectional view taken along line II-II in

[0054] - Figure 11 Schematically shows Figure 8 a sectional view taken along line III-III in

[0055] List of reference numerals in the technical solution and embodiments in the figure:

[0056] 1. Turbine outer ring

[0057] 1A. Body part

[0058] 1B. Extension part

[0059] 11. Toroidal surface

[0060] 12. Front mounting rib

[0061] 13. Rear mounting rib

[0062] 14. First mounting hole

[0063] 15. Second mounting hole 2. Front casing

[0064] 2A. Upper section of the front casing

[0065] 2B. Lower section of the front casing

[0066] 21. Lower edge convex rib

[0067] 22. Third mounting hole

[0068] 23. Step surface

[0069] 24. Front side convex rib

[0070] 25. Upper inner fitting surface

[0071] 26. Mounting through hole

[0072] 27. First cold air hole

[0073] 28. First mounting hook

[0074] 29. Front mounting connector 3. Middle casing

[0075] 3A, Upper part of the middle casing

[0076] 3B, Lower part of the middle casing

[0077] 3B1, Front side of the lower part of the middle casing 3B2, Rear side of the lower part of the middle casing 31, Impact cover plate

[0078] 32, First contact rib

[0079] 33, First blind hole

[0080] 34, Second blind hole

[0081] 35, Body of the lower part of the middle casing

[0082] 36, Body of the upper part of the middle casing

[0083] 37, Gas collecting groove

[0084] 38, Cold air hole

[0085] 39, First through hole

[0086] 311, Impact cooling hole

[0087] 321, First notch

[0088] 351, Slope-shaped protrusion

[0089] 352, Lower cavity

[0090] 361, Front side of the upper part of the middle casing 362, Lower ring surface of the upper part of the middle casing 363, Upper ring surface of the lower part of the middle casing 364, Rear side of the upper part of the middle casing 4, Rear casing

[0091] 4A, Upper part of the rear casing

[0092] 4B, Lower part of the rear casing

[0093] 41, Second contact flange

[0094] 42, Fourth mounting hole

[0095] 43, Rear outer rib

[0096] 44, Vertical flange

[0097] 45, Horizontal section

[0098] 46, First groove

[0099] 47, Second through hole

[0100] 48, Second mounting hook

[0101] 49, Rear mounting connector

[0102] 411. Second notch

[0103] 451. Upper rib

[0104] 452. Second groove

[0105] 453. Front side of the horizontal section

[0106] 454. Lower circumferential surface of the horizontal section

[0107] 5. First connecting member

[0108] 51. Left cylindrical section

[0109] 52. Intermediate section

[0110] 521. Convex plane

[0111] 53. Right cylindrical section

[0112] 6. Second connecting member

[0113] 61. Left cylindrical portion

[0114] 62. Middle convex portion

[0115] 63. Right cylindrical portion Detailed implementation manners

[0116] In order to make the purpose, technical solutions and advantages of the implementation of the present invention clearer, the technical solutions in the embodiments of the present invention will be described in more detail below with reference to the accompanying drawings in the embodiments of the present invention.

[0117] In this regard, it should be first pointed out that in the specific description process of these embodiments, for the sake of concise description, it is impossible for this specification to describe all features of the actual embodiments in detail. It should be understood that in the actual implementation process of any one of the embodiments, just as in the process of any engineering project or design project, in order to achieve the specific goals of the developer and to meet system-related or business-related restrictions, various specific decisions are often made, and this will also change from one embodiment to another. In addition, it can also be understood that although the efforts made in this development process may be complex and lengthy, for those of ordinary skill in the art related to the content disclosed in the present invention, some design, manufacturing or production changes made on the basis of the technical content disclosed in this disclosure are only conventional technical means and should not be understood as the content of this disclosure being insufficient.

[0118] In addition, it should be noted that unless otherwise defined, the technical terms or scientific terms used in the claims and the specification should have the ordinary meanings understood by those with ordinary skills in the technical field to which the present invention pertains. Words such as "a" or "an" do not denote a limitation of quantity, but rather indicate the existence of at least one. Words such as "comprising" or "including" mean that the elements or items appearing before "comprising" or "including" cover the elements or items listed after "comprising" or "including" and their equivalent elements, without excluding other elements or items. Words such as "connected" or "coupled" are not limited to physical or mechanical connections, nor are they limited to direct or indirect connections.

[0119] In addition, in the following description, the orientation or positional relationship indicated by terms such as "radial", "axial", "inner", "outer" or other orientation terms is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or component referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present invention.

[0120] Meanwhile, specific words are used in the present application to describe the embodiments of the present application. For example, "an embodiment" and / or "one embodiment" mean a certain feature, structure or characteristic related to at least one embodiment of the present application. Therefore, it should be emphasized and noted that the "one embodiment" or "an embodiment" mentioned twice or more at different positions in this specification is not necessarily referring to the same embodiment. In addition, certain features, structures or characteristics in one or more embodiments of the present application can be appropriately combined.

[0121] Ceramic matrix composites: Ceramic matrix composites are a class of composites in which ceramics are used as the matrix and are combined with various fibers. They usually have excellent properties such as high temperature resistance, high strength and modulus, low density, and strong corrosion resistance, and have broad application prospects in hot-end structural components of aerospace.

[0122] Turbine shroud: The turbine shroud is the main stationary part of the turbine of a gas turbine engine. It is installed on the casing corresponding to the rotating blades of the turbine, and withstands high temperature and high pressure service environments. It is required to be able to expand freely and be wear-resistant to adapt to the expansion of the casing and the appropriate rubbing of the rotating blades of the turbine.

[0123] The thermal conductivities and coefficients of thermal expansion of CMC ceramic matrix composites and metal materials differ significantly. At high temperatures, the deformation of metal materials is large, while that of CMC ceramic matrix composites is small. Therefore, the connection between CMC ceramic matrix composites and metal materials is particularly important. It is necessary to ensure the functions of the structure, transfer loads, and limit displacements, while also avoiding the damage of CMC ceramic matrix composites caused by inconsistent deformations of metal materials and CMC ceramic matrix composites. Therefore, when applying CMC ceramic matrix composite outer rings to aero-engine components, the problem of thermal mismatch connection between the outer ring and metal parts needs to be considered. Thermal mismatch refers to the phenomenon that adjacent materials or components with different coefficients of thermal expansion within the same system exhibit inconsistent magnitudes of thermal expansion deformation during temperature changes. Unreleased thermal deformation mismatch will cause significant thermal mismatch stress within the system.

[0124] The turbine outer ring connection structure of the present invention can effectively alleviate the problem of thermal deformation mismatch inside the assembly structure, and avoid problems such as excessive thermal mismatch stress or relaxation of the installation pre-tightening force, as well as structural strength failure, precise installation and positioning failure, or vibration and collision problems, thereby effectively improving the safety and reliability of the assembly structure.

[0125] Hereinafter, a preferred embodiment of the turbine outer ring connection structure of the present invention will be described in detail with reference to the accompanying drawings, so that the advantages and features of the present invention can be easily understood by those skilled in the art, thereby making the scope of the present invention more clearly defined.

[0126] Generally speaking, the present invention relates to a turbine outer ring connection structure. Figure 1 The structural schematic diagram of the turbine outer ring connection structure of a specific embodiment of the present invention is schematically shown.

[0127] As Figure 1 shown, the turbine outer ring connection structure of the present invention includes a turbine outer ring 1 and a middle casing. Among them, the structure of the turbine outer ring 1 is similar to a π shape, which is convenient for manufacturing. The middle casing adopts a three-section structure, divided into a front section, a middle section, and a rear section. These three sections respectively include a front casing 2, a middle casing 3, and a rear casing 4. These three are preferably installed and pre-tightened axially in the engine through two groups of connecting pieces, such as a first connecting piece 5 and a second connecting piece 6. The material of the turbine outer ring 1 is a first material, and the material of the middle casing is a second material, wherein the coefficient of thermal expansion of the first material is less than that of the second material. Generally, the material of the turbine outer ring 1 is a ceramic matrix composite CMC, and the material of the middle casing is metal, preferably a superalloy.

[0128] The meaning of the "turbine outer ring" here refers to the component of an aero-engine that isolates the high-temperature gas erosion and maintains the integrity of the casing structure.

[0129] As used herein, the "intermediate casing" refers to a load-bearing component on an aeroengine, which is a stationary part. When an engine blade falls off, it contains the blade.

[0130] Next, each component will be described in detail one by one:

[0131] Outer Turbine Ring 1

[0132] Figure 2 The structural schematic diagram of the turbine outer ring according to a specific embodiment of the present invention is schematically shown.

[0133] As Figure 2 shown, the turbine outer ring 1 of the present invention includes a body portion 1A and an extension portion 1B.

[0134] The body portion 1A has an annular surface 11, which is used to form the wall of the combustion gas flow passage, and thus belongs to the functional area of the turbine outer ring 1.

[0135] The extension portion 1B includes a front mounting rib plate 12 and a rear mounting rib plate 13 that extend radially and axially adjacent to each other from the body portion 1A perpendicular to the annular surface 11 for connection and assembly. The annular surface 11 is located between the front mounting rib plate 12 and the rear mounting rib plate 13 and partially protrudes outward. As Figure 2 shown in the preferred embodiment, the height of the rear mounting rib plate 13 is higher than that of the front mounting rib plate 12.

[0136] In one embodiment, at least two first mounting holes 14 are provided on the front mounting rib plate 12, only one of which is a circular through hole, and the rest are all runway-shaped long holes. Similarly, at least two second mounting holes 15 are provided on the rear mounting rib plate 13, only one of which is a circular through hole, and the rest are also all runway-shaped long holes. It is worth mentioning that the circular through holes on different mounting rib plates are located on the same rotary cross-section.

[0137] Front Casing 2

[0138] Figure 3 The structural schematic diagram of the front casing of the intermediate casing according to a specific embodiment of the present invention is schematically shown.

[0139] As Figure 3 shown, in a preferred embodiment, the front casing 2 is integrally sheet-shaped and includes a front upper casing 2A and a front lower casing 2B.

[0140] At the lower end of the front lower casing 2B, a lower edge ridge 21 is axially and rearwardly provided, as Figure 3As shown, in a preferred embodiment, the circumferential shape of the lower edge rib 21 is arc-shaped. Of course, it is not limited thereto and can also be linear as required. The lower edge rib 21 is used to be close to the front side surface of the front mounting rib 12 of the turbine outer ring 1 in the installation state, so as to form a controllable axial assembly gap (i.e., cold air leakage gap). The third mounting holes 22 are circumferentially distributed along the inner surface of the lower part 2B of the front casing, and are used for interference fitting of front mounting connectors 29 such as pins. The stepped surface 23 is formed at the junction of the lower part 2B of the front casing and the upper part 2A of the front casing, and extends backward along the engine axis.

[0141] The upper part 2A of the front casing has an upper inner fitting surface 25. The upper inner fitting surface 25 and the stepped surface 23 are respectively used as the radial and axial installation limiting fitting surfaces between the front casing 2 and the middle casing 3. The front rib 24 is axially formed forward at the junction of the lower part 2B of the front casing and the upper part 2A of the front casing, and is used as the installation contact interface of adjacent components. The installation through holes 26 are circumferentially distributed along the upper inner fitting surface 25. Figure 7 As shown, when in the installation state, the installation through holes 26 are used for the first connector 5 and the second connector 6 to pass through, so as to apply an axial installation pre-tightening force. The first cold air holes 27 are circumferentially distributed between the installation through holes 26 along the upper inner fitting surface 25. In a preferred embodiment, the first cold air holes 27 are centrally arranged on the upper inner fitting surface 25. A first installation hook 28 is radially arranged inwardly at the upper end of the upper part 2A of the front casing, and is used for the installation and fixation between the turbine outer ring 1 and the middle casing and the engine bearing casing.

[0142] As shown in Figure 7 When in the installation state, the front mounting connector 29 passes through the first mounting hole 14 on the front mounting rib 12 of the turbine outer ring 1, so as to limit the circumferential and radial displacement of the turbine outer ring 1 along the engine.

[0143] Intermediate Casing 3

[0144] Figure 4 Schematically shows the structural schematic diagram of the middle casing of the middle casing of a specific embodiment of the present invention.

[0145] As shown in Figure 4 In a preferred embodiment, the middle casing 3 includes an upper part 3A of the middle casing and a lower part 3B of the middle casing. The upper part 3A of the middle casing is integrally in an L-shaped sheet, and the lower part 3B of the middle casing is in a hollow rectangular shape.

[0146] The lower part 3B of the middle casing includes the main body 35 of the lower part of the middle casing, the front side surface 3B1 of the lower part of the middle casing in the radially inward direction, and the rear side surface 3B2 of the lower part of the middle casing. The main body 35 of the lower part of the middle casing is in the shape of a hollow rectangular block and has an upper ring surface 363 of the lower part of the middle casing. The impact cover plate 31 is in the shape of a thin plate and is preferably connected to the lower surface of the lower part 3B of the middle casing by welding. In one embodiment, impact cooling holes 311 are provided on the impact cover plate 31, and these impact cooling air holes 311 are used to rectify the flow of cold air, so as to form impact cooling on the outer ring surface of the turbine outer ring 1. At the lower end of the rear side surface 3B2 of the lower part of the middle casing, a first contact convex rib 32 is axially arranged backward, as Figure 4 shown. In a preferred embodiment, the circumferential shape of the first contact convex rib 32 is arc-shaped. Of course, it is not limited thereto and can also be linear as required. The first contact convex rib 32 is used to press against the inner surface of the rear mounting rib plate 13 of the turbine outer ring 1 and apply a normal pressing force in the installed state. A first notch 321 is formed on the first contact convex rib 32, and this first notch is used as a cold air flow passage. The first blind hole 33 is circumferentially provided on the rear side surface 3B2 of the lower part of the middle casing to prevent the end of the rear mounting connecting piece 49 from slipping and falling when inserted. Similarly, the second blind hole 34 is circumferentially provided on the front side surface 3B1 of the lower part of the middle casing to prevent the end of the front mounting connecting piece 29 from slipping and falling when inserted.

[0147] The upper part 3A of the middle casing includes the main body 36 of the upper part of the middle casing, the lower ring surface 362 of the upper part of the middle casing, the front side surface 361 of the upper part of the middle casing in the radially inward direction, and the rear side surface 364 of the upper part of the middle casing. The main body 36 of the upper part of the middle casing is in an overall L-shaped sheet. A sloping convexity 351 is formed between the upper ring surface 363 of the lower part of the middle casing of the main body 35 of the lower part of the middle casing and the rear side surface 364 of the upper part of the middle casing, and it has a lower cavity 352 inside. A gas collecting groove 37 is provided at a position on the front side surface 361 of the upper part of the middle casing corresponding to the sloping convexity on the rear side surface 364 of the upper part of the middle casing. Preferably, both the sloping convexity 351 and the gas collecting groove 37 are centrally arranged. A second cold air hole 38 is provided at the bottom of the gas collecting groove 37 and obliquely leads into the lower cavity 352. Among them, the sloping convexity 351 is used to provide an area for the processing and forming of the second cold air hole 38, and at the same time increases the overall stiffness of the middle casing 3. The gas collecting groove 37 is used to solve the problem of unsmooth cold air passage caused by inaccurate installation alignment of the first cold air hole 27 in the upper part 2A of the front casing and the second cold air hole 38 in the upper part of the middle casing. The first through holes 39 are circumferentially distributed along the main body 36 of the upper part of the middle casing. Combining Figure 7 shown, when in the installed state, the first through holes 39 are used for the first connecting piece 5 and the second connecting piece 6 to pass through, so as to apply an axial installation pre-tightening force.

[0148] Combining Figure 7As shown, the front side surface 361 of the upper section of the middle casing and the lower annular surface 362 of the upper section of the middle casing are used as the axial and radial limiting and fitting surfaces for the installation of the middle casing 3 and the front casing 2. The rear side surface 364 of the upper section of the middle casing and the upper annular surface 365 of the lower section of the middle casing are used as the axial and radial limiting and fitting surfaces for the installation of the middle casing 3 and the rear casing 4.

[0149] Rear Casing 4

[0150] Figure 5 The structural schematic diagram of the rear casing of the middle casing of a specific embodiment of the present invention is schematically shown.

[0151] As Figure 5 shown, in a preferred embodiment, the rear casing 4 includes an upper section 4A of the rear casing and a lower section 4B of the rear casing. The upper section 4A of the rear casing includes a horizontal section 45, and the lower section 4B of the middle casing includes a vertical flange 44 that extends radially downward from the horizontal section 45.

[0152] In the lower section 4B of the rear casing, a second contact convex rib 41 is axially and forwardly provided at the lower part of the vertical flange 44. As Figure 5 shown, in a preferred embodiment, the circumferential shape of the second contact convex rib 41 is arc-shaped. Of course, it is not limited thereto and can also be linear as required. The second contact convex rib 41 is used to press against the outer surface of the rear mounting rib 13 of the turbine outer ring 1 in the installation state and apply a normal pressing force. A second notch 411 is formed on the second contact convex rib 41, and this second notch is used as a cold air flow channel. Among them, the first notch 321 of the middle casing 3 and the second notch 411 of the rear casing 4 are staggeredly distributed in the circumferential direction. The fourth mounting holes 42 are circumferentially distributed along the inner surface of the vertical flange 44 and are used for interference fitting of rear mounting connectors 49 such as pins. A rear outer convex rib 43 is axially and backwardly formed at the lower end of the vertical flange 44 and is used to provide an installation contact interface for adjacent components.

[0153] In the upper section 4A of the rear casing, a first groove 46 is formed between the front side surface 453 of the horizontal section of the horizontal section 45 and the lower annular surface 454 of the horizontal section, and is used to provide an installation space for the slope-shaped protrusion 351 on the rear side surface 364 of the upper section of the middle casing during installation. Therefore, the setting position of the first groove 46 corresponds to the setting position of the slope-shaped protrusion 351. Similarly, the first groove 46 is preferably centered. The second through holes 47 are circumferentially distributed along the horizontal section 45. As Figure 7 shown, when in the installation state, the second through holes 47 are used for the first connector 5 and the second connector 6 to pass through, so as to apply an axial installation pre-tightening force. A second installation hook 48 is provided at the upper end of the horizontal section 45 and is used for the installation and fixation between the turbine outer ring 1 and the middle casing and the engine bearing casing. An upper rib 451 is also provided on the horizontal section 45 and is used to increase the overall stiffness of the rear casing 4. AsFigure 5 As shown, in a preferred embodiment, the upper rib plate 451 is located on both sides of the first groove 46. The second groove 452 is adjacent to the upper rib plate 451, and the second groove provides a space for arranging the second connecting member 6.

[0154] Combined Figure 7 As shown, when in the installed state, the rear mounting connecting member 49 passes through the second mounting hole 15 on the rear mounting rib plate 13 of the turbine outer ring 1, thereby restricting the circumferential and radial displacements of the turbine outer ring 1 along the engine. The front side surface 453 of the horizontal section of the horizontal section 45 and the lower ring surface 454 of the horizontal section are used as the axial and radial limiting and fitting surfaces when the rear casing 4 and the middle casing 3 are installed.

[0155] First Connector 5, Second Connector 6

[0156] Figure 6 The schematic structural diagrams of the first connecting member and the second connecting member of a specific embodiment of the present invention are schematically shown.

[0157] It is worth mentioning here that the first connecting member 5 and the second connecting member 6 are generally threaded connecting members, for example Figure 6 the nut and bolt structure shown in, so that not only the material cost is saved, but also the assembly is easy.

[0158] Such as Figure 6 As shown, in an embodiment, the outer contour of the first connecting member 5 is generally divided into three sections along the axial direction, namely the left cylindrical section 51, the middle section 52 and the right cylindrical section 53. The first connecting member 5 is entirely hollow and has a threaded through hole extending axially in the middle. Combined Figure 7 As shown, during installation, the left cylindrical section 51 passes through the second through hole 47 of the rear casing 4 and the first through hole 39 of the middle casing 3 in sequence, and then inserts into most of the depth of the installation through hole 26 of the front casing 2. The length of the left cylindrical section 51 is greater than the sum of the depths of the second through hole 47 of the rear casing 4 and the first through hole 39 of the middle casing 3, but at the same time less than the sum of the depths of the second through hole 47 of the rear casing 4, the first through hole 39 of the middle casing 3 and the installation through hole 26 of the front casing 2. And, the diameter of the outer ring surface of the left cylindrical section 51 is designed such that, in the installed state, a tight fit is achieved between the outer ring surface of the left cylindrical section 51 and the inner ring surfaces of the second through hole 47 of the rear casing 4, the first through hole 39 of the middle casing 3 and the installation through hole 26 of the front casing 2, thereby playing a role of relative positioning for the combined installation of the front casing, the middle casing and the rear casing.

[0159] The outer surface profile of the middle section 52 of the first connecting member 5 is the largest among the three sections. One side of the outer surface of the middle section 52 has a convex plane 521, which is used for limiting abutment with the adjacent surface of the rear casing 4, so as to prevent the first connecting member 5 from displacing following the rotation of the second connecting member 6 during the application of the installation pre-tightening force, thereby affecting the application of the installation pre-tightening force. Still as Figure 6 shown, in an embodiment, the outer contour of the second connecting member 6 is generally divided into three sections along the axial direction, which are the left cylindrical section 61, the middle convex section 62, and the right cylindrical section 63. Among them, the left cylindrical section 61 adopts a screw form. In the installed state, the left cylindrical section 61 is screwed into the entire threaded through-hole of the first connecting member 5 and partially passes out from the right cylindrical section 53 of the first connecting member 5, so as to be engaged with the threaded through-hole of the first connecting member 5 through thread fitting. The internal threaded hole corresponding to the right cylindrical section 53 of the first connecting member 5 is designed with an anti-loosening feature for anti-loosening setting with the second connecting member 6. The middle convex section 62 of the second connecting member 6 is used for limiting abutment with the adjacent surface of the front casing 2 during installation.

[0160] Next, the assembly between the turbine outer ring 1 of the present invention and the middle casing will be specifically described:

[0161] First, Figure 7 The assembly schematic diagram of the turbine outer ring 1 and the middle casing of a specific embodiment of the present invention is schematically shown.

[0162] As Figure 7 shown, during the assembly process, first place the lower body 35 of the middle section of the middle casing 3 between the front mounting rib 12 and the rear mounting rib 13 of the turbine outer ring 1. Then, press the front casing 2 and the rear casing 4 from the front and rear sides on the middle casing 3 and the turbine outer ring 1 respectively, so that the front mounting connecting member 29 and the rear mounting connecting member 49 respectively pass through the first mounting hole 14 and the second mounting hole 15 on the turbine outer ring 1, and then are respectively inserted into the second blind hole 34 and the first blind hole 33 of the middle casing 3. Furthermore, pass the left cylindrical section 51 of the first connecting member 5 through the second through-hole 47 of the rear casing 4, the first through-hole 39 of the middle casing 3, and the mounting through-hole 26 of the front casing 2 in sequence. Finally, screw the second connecting member 6 into the first connecting member 5 and apply the installation pre-tightening force, so that the assembly and the application of the installation pre-tightening force between the turbine outer ring 1 and the middle casing are completed.

[0163] As described above, the turbine outer ring connection structure of the present invention adopts a three-section middle casing for assembling a double-installation rib plate type turbine outer ring, realizing the assembly between the turbine outer ring and the middle casing. By reserving an assembly gap and reasonably setting the installation pre-tightening force application scheme, the problem of thermal deformation mismatch inside the assembly structure is solved, and problems such as excessive thermal mismatch stress, relaxation of installation pre-tightening force, and vibration and collision are avoided. The positions for applying the installation pre-tightening force between the turbine outer ring and the middle casing are the inner and outer sides of the rear installation rib plate, which is beneficial to reducing the preparation and processing accuracy requirements of the turbine outer ring, improving the outer ring installation stress level, and preventing the relaxation of the installation pre-tightening force.

[0164] Next, Figure 8 -11 shows a cross-sectional view of the turbine outer ring 1 and the middle casing in the installed state, where Figure 8 schematically shows a cross-sectional position guiding diagram, Figure 9 schematically shows along Figure 8 a schematic cross-sectional view taken along line I-I in Figure 10 schematically shows along Figure 8 a schematic cross-sectional view taken along line II-II in Figure 11 schematically shows along Figure 8 a schematic cross-sectional view taken along line III-III in

[0165] As Figure 9 shown, when in the installed state, there is a clearance fit between the end face of the rear installation connector 49 and the first blind hole 33 of the middle casing 3, and the end face of the installation connector 29 is in abutting contact with the bottom surface of the second blind hole 34 of the middle casing 3, or it can also be a clearance fit.

[0166] As Figure 10 shown, when in the working state, the cooling gas enters from the front side of the upper section 2A of the front casing, and after flowing through the first cooling air holes 27 of the front casing 2, the gas collection groove 37 and the cooling air holes 38 of the middle casing 3, it flows into the lower cavity 352 of the lower section body 35 of the middle casing lower section. Subsequently, it flows through the impingement cooling holes 311 on the impingement cover plate 31 of the middle casing 3 to impingement cool the cold side ring surface of the turbine outer ring, and then flows through the gap surrounded by the turbine outer ring 1 and the middle casing. Part of the cooling gas bypasses the front installation rib plate 12 of the turbine outer ring 1 and flows forward through the gap between the lower edge ridge 21 of the front casing 2 and the front installation rib plate 12 and then flows into the gas flow path, while the other part of the cooling gas flows around the rear installation rib plate 13 of the turbine outer ring 1 and flows backward through the first notch 321 of the middle casing 3 and the second notch 411 of the rear casing 4 and then flows into the gas flow path. The above cold air flow path and cooling scheme of the present invention can efficiently cool the turbine outer ring 1 and the middle casing, thus minimizing the over-temperature risk.

[0167] Again, as Figure 11As shown, under the axial installation pre-tightening force generated by the first connecting member 5 and the second connecting member 6 and the installation positioning effect of the first connecting member 5, the inner fitting surface 25 on the upper part of the front casing 2 and the front side surface 361 of the upper section of the middle casing 3 of the middle casing 3 are axially limited and fitted, the step surface 23 of the front casing 2 and the lower ring surface 362 of the upper section of the middle casing 3 of the middle casing 3 are radially limited and fitted, the rear side surface 364 of the upper section of the middle casing 3 and the front side surface 453 of the horizontal section of the rear casing 4 are axially limited and fitted, and the upper ring surface 363 of the upper section of the middle casing 3 and the lower ring surface 454 of the horizontal section of the rear casing 4 are radially limited and fitted. A clearance fit is also maintained between the lower edge ridge 21 of the front casing 2 and the front mounting rib 12 of the turbine outer ring 1. The axial installation pre-tightening force generated by the first connecting member 5 and the second connecting member 6 is transmitted to their respective first contact ridges 32 and second contact ridges 41 through the middle casing 3 and the rear casing 4, and then clamps the two side surfaces of the rear mounting rib 13 of the turbine outer ring from both sides to generate a normal pressing force. According to the above structure, the present invention can realize the application of the installation pre-tightening force and the axial limit fixation between the turbine outer ring 1 and the middle casing, while alleviating the problem of axial thermal deformation mismatch inside the assembly structure, and avoiding problems such as excessive thermal mismatch stress, relaxation of the installation pre-tightening force, and vibration and collision, significantly improving the safety and reliability of the connection structure.

[0168] In addition, during the temperature change process, the problem of thermal deformation mismatch between the first mounting hole 14 and the second mounting hole 15 of the turbine outer ring 1 and the front mounting connecting member 29 and the rear mounting connecting member 49 is alleviated by the assembly clearance reserved between them. The problem of thermal deformation mismatch between the whole turbine outer ring 1 and the middle casing along the engine axis is alleviated by the fitting clearance at the lower edge ridge 21 of the front casing 2. In addition, the problem of thermal deformation mismatch in the radial and circumferential directions of the engine is alleviated by the relative sliding between the second contact ridge 41 of the rear casing 4 and the first contact ridge 32 of the middle casing 3. As for the problem of thermal deformation mismatch between the rear mounting rib 13 of the turbine outer ring 1 and the rear casing 4 and the middle casing 3, it is alleviated by the elastic deformation rebound of the installation pre-tightening force loaded on the rear casing 4 and the middle casing 3, thus effectively preventing the occurrence of problems such as relaxation of the installation pre-tightening force and vibration and collision.

[0169] In summary, the present invention provides a connection structure for a turbine outer ring of a gas turbine engine, including a structural solution, a cooling solution, an assembly solution, and a mounting pre-tightening force application solution. Among them, on the radially outer side of the turbine outer ring, two mounting rib plates perpendicular to the ring surface along the axial direction are designed and prepared, and at least two mounting through holes are designed and machined on each mounting rib plate. At most one of the mounting through holes on the same rib plate is a circular through hole, and the rest are runway-shaped long holes. The middle casing is divided into three sections: front, middle, and rear. The three are axially mounted and pre-tightened on the engine shaft by two sets of bolts and nuts. At least two connecting pieces are respectively mounted on the front casing and the rear casing. In the mounted state, the above-mentioned connecting pieces pass through the mounting holes on the mounting rib plates of the turbine outer ring and are inserted into the counterbore holes of the middle casing to perform circumferential and radial mounting positioning of the turbine outer ring on the engine. In the mounted state, the pre-tightening force of the connecting piece is transmitted to their respective contact ridges through the middle casing and the rear casing, clamping the double-sided surfaces of the rear mounting rib plate of the turbine outer ring from the front and rear sides and generating a normal pressing force, thereby realizing the application of the mounting pre-tightening force between the turbine outer ring and the middle casing, and further restricting the axial displacement of the turbine outer ring along the engine. In another embodiment, the two contact ridges are respectively arranged on the front side surfaces of the front casing and the lower section of the middle casing. The axial pre-tightening force of the connecting piece is transmitted to the above-mentioned contact ridges through the front casing and the middle casing, and the front mounting rib plate is clamped in the normal direction from the inner and outer side surfaces of the front mounting rib plate of the outer ring. An axial gap is provided between the edge ridge of the rear casing and the outer side surface of the rear rib plate of the outer ring.

[0170] During the temperature change process, the above-mentioned pressing force is maintained by the elastic deformation rebound of the pre-tightening force loaded by the middle casing, preventing the relaxation of the above-mentioned pressing force and the occurrence of vibration and collision problems between the turbine outer ring and the middle casing assembly. A clearance fit is provided between the front mounting rib plate of the turbine outer ring and the front casing and the middle casing to relieve the thermal deformation mismatch between the turbine outer ring and the middle casing along the engine axis. The aperture of the mounting hole of the turbine outer ring rib plate is larger than the diameter of the corresponding metal connecting piece, so that the thermal deformation mismatch problem between the two is relieved through the assembly clearance between them, while the thermal deformation mismatch between the turbine outer ring and the middle casing along the circumferential and radial directions of the engine is relieved through the relative sliding with the contact ridges. In addition, since the lower section of the middle casing is a hollow structure and its lower surface is an impact cover plate structure with impact cooling holes, the cold side ring surface of the turbine outer ring is also subjected to impact cooling.

[0171] Although the turbine outer ring connection structure disclosed in the embodiments of the present application is applicable to a gas turbine engine to achieve the effect of preventing thermal stress caused by thermal mismatch, it is not limited thereto. As long as the connection is to prevent high stress caused by non-uniform deformation, the connection structure disclosed in the embodiments of the present application can be applied.

[0172] The preferred embodiments of the present invention have been described in detail above. However, it should be understood that after reading the above teachings of the present invention, those skilled in the art will readily think of other advantages and modifications. Therefore, in its broader aspects, the present invention is not limited to the specific details and representative embodiments shown and described herein. Accordingly, those skilled in the art can reasonably combine or modify the elements of the above embodiments so as to make various modifications without departing from the spirit or scope of the general inventive concept of the present invention as defined by the appended claims and their equivalents.

Claims

1. A turbine outer ring connection structure, comprising: A turbine outer ring, the turbine outer ring includes a body portion and an extension portion, the body portion has an annular surface, and the extension portion includes a front mounting rib plate and a rear mounting rib plate that extend radially and axially adjacent from the body portion perpendicular to the annular surface; An intermediate casing, which adopts a three-section type and includes a front casing, an intermediate casing, and a rear casing; Wherein, the front casing is detachably connected to the front mounting rib plate of the turbine outer ring, the rear casing is detachably connected to the rear mounting rib plate of the turbine outer ring, and the front casing, the intermediate casing, and the rear casing are detachably connected to be pre-tightened in the axial direction of the engine and form axial clamping and clearance fit between the turbine outer ring and the intermediate casing.

2. The turbine outer ring connection structure according to claim 1, characterized in that, The turbine outer ring connection structure further includes a first connecting member and a second connecting member; The front casing and the rear casing respectively include a front mounting connecting member and a rear mounting connecting member; A first mounting hole and a second mounting hole are respectively formed on the front mounting rib plate and the rear mounting rib plate of the turbine outer ring; The front casing has a mounting through hole, the intermediate casing has a first through hole, a first blind hole, and a second blind hole, and the rear casing has a second through hole; The front mounting connecting member sequentially passes through the first mounting hole of the turbine outer ring and the second blind hole of the intermediate casing to detachably connect the front casing to the front mounting rib plate of the turbine outer ring; The rear mounting connecting member sequentially passes through the second mounting hole of the turbine outer ring and the first blind hole of the intermediate casing to detachably connect the rear casing to the rear mounting rib plate of the turbine outer ring; The first connecting member sequentially passes through the second through hole of the rear casing, the first through hole of the intermediate casing, and the mounting through hole of the front casing, and the second connecting member is screwed into the first connecting member and an installation pre-tightening force is applied.

3. The turbine outer ring connection structure according to claim 2, characterized in that, At least two first mounting holes are formed on the front mounting rib plate, only one of which is a circular through hole, and the rest are runway-shaped long holes, and at least two second mounting holes are also formed on the rear mounting rib plate, only one of which is a circular through hole, and the rest are runway-shaped long holes; and The circular through holes on different mounting rib plates are located on the same rotary section.

4. The turbine outer ring connection structure according to claim 2, characterized in that, The front casing includes an upper section of the front casing and a lower section of the front casing; A lower edge convex rib is axially and rearwardly provided at the lower end of the lower section of the front casing, and the lower edge convex rib is close to the front side surface of the front mounting rib plate of the turbine outer ring in the installation state, thereby forming an axial assembly gap; The upper section of the front casing has an upper inner fitting surface and a step surface, and the upper inner fitting surface and the step surface are respectively used as axial and radial installation limiting fitting surfaces between the front casing and the intermediate casing.

5. The turbine outer ring connection structure according to claim 4, characterized in that, First cold air holes are circumferentially distributed between the mounting through holes along the upper inner fitting surface.

6. The turbine outer ring connection structure according to claim 2, characterized in that, the intermediate casing includes an upper intermediate casing section and a lower intermediate casing section; the lower intermediate casing section is hollow, and an impact cover plate is connected to the lower surface of the lower intermediate casing section. Impact cooling holes are provided on the impact cover plate for impact cooling the outer ring surface of the turbine outer ring.

7. The turbine outer ring connection structure according to claim 6, characterized in that, the lower intermediate casing section includes an upper ring surface of the lower intermediate casing section, a front side surface of the lower intermediate casing section, and a rear side surface of the lower intermediate casing section; the upper intermediate casing section includes a lower ring surface of the upper intermediate casing section, a front side surface of the upper intermediate casing section, and a rear side surface of the upper intermediate casing section; the front side surface of the upper intermediate casing section and the lower ring surface of the upper intermediate casing section serve as the axial and radial limit fitting surfaces when the intermediate casing is installed with the front casing, and the rear side surface of the upper intermediate casing section and the upper ring surface of the lower intermediate casing section serve as the axial and radial limit fitting surfaces when the intermediate casing is installed with the rear casing.

8. The turbine outer ring connection structure according to claim 7, characterized in that, a first contact convex rib is axially and rearwardly provided at the lower end of the rear side surface of the lower intermediate casing section. The first contact convex rib is used to press against the inner surface of the rear mounting rib plate of the turbine outer ring in the installed state and apply a normal pressing force.

9. The turbine outer ring connection structure according to claim 7, characterized in that, a first notch is formed on the first contact convex rib and serves as a cold air flow channel.

10. The turbine outer ring connection structure according to claim 7, characterized in that, a sloping protrusion is formed between the upper ring surface of the lower intermediate casing section and the rear side surface of the upper intermediate casing section, and a lower cavity is provided inside it; a gas collecting groove is provided at a position corresponding to the sloping protrusion on the front side surface of the upper intermediate casing section and the rear side surface of the upper intermediate casing section. A second cold air hole leading to the lower cavity is provided at the bottom of the gas collecting groove.

11. The turbine outer ring connection structure according to claim 2, characterized in that, the rear casing includes an upper rear casing section and a lower rear casing section; a second contact convex rib is axially and forwardly provided at the lower part of the lower rear casing section. The second contact convex rib is used to press against the outer surface of the rear mounting rib plate of the turbine outer ring in the installed state and apply a normal pressing force.

12. The turbine outer ring connection structure according to claim 11, characterized in that, a second notch is formed on the second contact convex rib and serves as a cold air flow channel, and a first contact convex rib is axially and rearwardly provided at the lower end of the rear side surface of the lower intermediate casing section of the intermediate casing. A first notch is formed on the first contact convex rib, and the first notch and the second notch are staggeredly distributed in the circumferential direction.

13. The turbine outer ring connection structure according to claim 11, characterized in that, the upper rear casing section includes a horizontal section. The horizontal section has a front side surface of the horizontal section and a lower ring surface of the horizontal section. The front side surface of the horizontal section and the lower ring surface of the horizontal section serve as the axial and radial limit fitting surfaces when the rear casing is installed with the intermediate casing.

14. The turbine outer ring connection structure according to claim 2, It is characterized in that the first connecting member is in a three-section form, including a left cylindrical section, a middle section and a right cylindrical section, and the second connecting member is in a three-section form, including a left cylindrical part section, a middle convex part section and a right cylindrical part section.

15. The turbine outer ring connection structure according to claim 14, It is characterized in that the first connecting member is a nut and the second connecting member is a bolt.

16. The turbine outer ring connection structure according to claim 14, It is characterized in that the whole of the first connecting member is hollow and has a threaded through hole extending axially in the middle; and the left cylindrical part section of the second connecting member is in the form of a screw rod, and in the installed state, the left cylindrical part section is engaged with the threaded through hole of the first connecting member by screw thread fit.

17. The turbine outer ring connection structure according to claim 14, It is characterized in that one side of the outer surface of the middle section has a convex plane, and the convex plane is used for limiting abutment with the adjacent surface of the rear casing.

18. The turbine outer ring connection structure according to claim 2, It is characterized in that the front mounting connecting member and the rear mounting connecting member are dowel pins and are respectively mounted on the corresponding first mounting hole and the second mounting hole of the front casing and the rear casing by interference fit.

19. The turbine outer ring connection structure according to claim 1, It is characterized in that the material of the turbine outer ring is a ceramic matrix composite material, and the material of the middle casing is a superalloy material.

20. A gas turbine engine, It is characterized in that it includes the turbine outer ring connection structure according to any one of claims 1-19.

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