Patent Application
20200284166
The present disclosure relates generally to gas turbine engines and, more particularly, to cover plates secured by captive fasteners, allowing for inspection, repair or replacement of components within the gas turbine engines with reduced risk of foreign object damage.
Gas turbine engines typically include a fan section, a compressor section, a combustor section and a turbine section. During operation, air is pressurized in the compressor section and mixed with fuel and burned in the combustor section to generate hot combustion gases. The hot combustion gases are then communicated through the turbine section, where energy is extracted from the hot combustion gases to power the compressor section, the fan section and various other loads occurring within or proximate a gas turbine engine.
A core engine of a gas turbine engine typically includes the compressor, the combustor and the turbine, each of which is surrounded by a core engine casing. During the life cycles of such components, inspection, repair or replacement is often required. Various techniques for accomplishing such inspection, repair or replacement require removal or disassembly of the core engine casing, sections thereof or cover plates configured to enclose critical components of the engine. Such disassembly, even when limited to removal of cover plates, may result in inadvertent foreign object debris being introduced into the engine prior to reassembly. The foreign object debris may result in damage to the engine upon being placed back in operation.
A cover assembly is disclosed. In various embodiments, the cover assembly includes a cover configured to close a passageway through a casing, the cover having a first keyhole slot; and a first captive fastener configured to extend through the first keyhole slot and into the casing.
In various embodiments, the casing defines a casing contour and the cover defines a cover contour having the same shape as the casing contour. In various embodiments, the cover is configured to slide along the casing in a longitudinal direction. In various embodiments, the first keyhole slot is disposed on a first lateral side of the cover. In various embodiments, a second keyhole slot is disposed on a second lateral side of the cover. In various embodiments, the first keyhole slot and the second keyhole slot are aligned in the longitudinal direction.
In various embodiments, the first captive fastener includes a threaded body configured to extend through the casing. In various embodiments, the first captive fastener includes a first blocking member disposed on a first distal end of the first captive fastener. In various embodiments, a second captive fastener is configured to extend through the second keyhole slot and into the casing.
In various embodiments, the first captive fastener includes a first blocking member configured to prevent the first captive fastener from being removed from the casing. In various embodiments, a second captive fastener is configured to extend through a second keyhole slot and into the casing, the second captive fastener including a second blocking member configured to prevent the second captive fastener from being removed from the casing.
In various embodiments, the first keyhole slot and the second keyhole slot are aligned in a longitudinal direction and disposed, respectively, on a first lateral side and a second lateral side of the cover with respect to the longitudinal direction. In various embodiments, the first blocking member comprises at least one of a deformed portion, a weld and a pin member disposed on a first distal end of the first captive fastener.
A gas turbine engine is disclosed. In various embodiments, the gas turbine engine includes a casing; a cover configured to close a passageway through the casing, the cover having a first keyhole slot and a second keyhole slot, both the first keyhole slot and the second keyhole slot aligned along a longitudinal direction; a first captive fastener configured to extend through the first keyhole slot and into the casing; and a second captive fastener configured to extend through the second keyhole slot and into the casing.
In various embodiments, the first keyhole slot is disposed on a first lateral side of the cover and the second keyhole slot is disposed on a second lateral side of the cover. In various embodiments, the first captive fastener includes a first blocking member configured to prevent the first captive fastener from being removed from the casing and the second captive fastener includes a second blocking member configured to prevent the second captive fastener from being removed from the casing. In various embodiments, the first blocking member comprises at least one of a first deformed portion, a first weld and a first pin member disposed on a first distal end of the first captive fastener and the second blocking member comprises at least one of a second deformed portion, a second weld and a second pin member disposed on a second distal end of the second captive fastener.
A method for accessing a component housed within a casing is disclosed. In various embodiments, the method includes the steps of releasing a first captive fastener extending through a first keyhole slot of a cover and into the casing; releasing a second captive fastener extending through a second keyhole slot of the cover and into the casing; sliding the cover in a longitudinal direction with respect to the first keyhole slot and the second keyhole slot; and removing the cover from the casing to expose the component.
In various embodiments, the step of releasing the first captive fastener includes unthreading the first captive fastener a first distance from the casing and releasing the second captive fastener includes unthreading the second captive fastener a second distance from the casing. In various embodiments, the first captive fastener includes a first blocking member configured to prevent the first captive fastener from being removed from the casing and the second captive fastener includes a second blocking member configured to prevent the second captive fastener from being removed from the casing.
The subject matter of the present disclosure is particularly pointed out and distinctly claimed in the concluding portion of the specification. A more complete understanding of the present disclosure, however, may best be obtained by referring to the following detailed description and claims in connection with the following drawings. While the drawings illustrate various embodiments employing the principles described herein, the drawings do not limit the scope of the claims.
The following detailed description of various embodiments herein makes reference to the accompanying drawings, which show various embodiments by way of illustration. While these various embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosure, it should be understood that other embodiments may be realized and that changes may be made without departing from the scope of the disclosure. Thus, the detailed description herein is presented for purposes of illustration only and not of limitation. Furthermore, any reference to singular includes plural embodiments, and any reference to more than one component or step may include a singular embodiment or step. Also, any reference to attached, fixed, connected, or the like may include permanent, removable, temporary, partial, full or any other possible attachment option. Additionally, any reference to without contact (or similar phrases) may also include reduced contact or minimal contact. It should also be understood that unless specifically stated otherwise, references to “a,” “an” or “the” may include one or more than one and that reference to an item in the singular may also include the item in the plural. Further, all ranges may include upper and lower values and all ranges and ratio limits disclosed herein may be combined.
Referring now to the drawings,
The gas turbine engine 20 generally includes a low speed spool 30 and a high speed spool 32 mounted for rotation about an engine central longitudinal axis A relative to an engine static structure 36 via several bearing systems 38. The low speed spool 30 generally includes an inner shaft 40 that interconnects a fan 42, a low pressure compressor 44 and a low pressure turbine 46. The inner shaft 40 is connected to the fan 42 through a speed change mechanism, which in this gas turbine engine 20 is illustrated as a fan drive gear system 48 configured to drive the fan 42 at a lower speed than the low speed spool 30. The high speed spool 32 includes an outer shaft 50 that interconnects a high pressure compressor 52 and a high pressure turbine 54. A combustor 56 is arranged in the gas turbine engine 20 between the high pressure compressor 52 and the high pressure turbine 54. A mid-turbine frame 57 of the engine static structure 36 is arranged generally between the high pressure turbine 54 and the low pressure turbine 46 and may include airfoils 59 in the core flow path C for guiding the flow into the low pressure turbine 46. The mid-turbine frame 57 further supports the several bearing systems 38 in the turbine section 28. The inner shaft 40 and the outer shaft 50 are concentric and rotate via the several bearing systems 38 about the engine central longitudinal axis A, which is collinear with longitudinal axes of the inner shaft 40 and the outer shaft 50.
The air in the core flow path C is compressed by the low pressure compressor 44 and then the high pressure compressor 52, mixed and burned with fuel in the combustor 56, and then expanded over the high pressure turbine 54 and low pressure turbine 46. The low pressure turbine 46 and the high pressure turbine 54 rotationally drive the respective low speed spool 30 and the high speed spool 32 in response to the expansion. It will be appreciated that each of the positions of the fan section 22, the compressor section 24, the combustor section 26, the turbine section 28, and the fan drive gear system 48 may be varied. For example, the fan drive gear system 48 may be located aft of the combustor section 26 or even aft of the turbine section 28, and the fan section 22 may be positioned forward or aft of the location of the fan drive gear system 48.
In various embodiments, a cover assembly 100 is removably secured to a casing 102 that surrounds the various components within the core flow path C, including, for example, the low pressure compressor 44, the high pressure compressor 52, the combustor 56, the high pressure turbine 54 and the low pressure turbine 46. In various embodiments, the cover assembly includes a cover 104 and one or more captive fasteners 106 configured to extend through the cover 104 and into the casing 102. The cover assembly 100 permits access to various of the components housed within the casing 102. For example, removal of the cover 104 provides access to a passageway 108 that extends through the casing 102. Access to the passageway 108 then provides access to at least one of the various components housed within the casing 102, such as, for example, a turbine rotor or stator blade disposed on one of the high pressure turbine 54 and the low pressure turbine 46 or a compressor rotor or stator blade disposed on one of the low pressure compressor 44 and the high pressure compressor 52. Access to the various components enables inspection, repair or replacement of the components without disassembly of the casing 102.
Referring now to
In various embodiments, the one or more captive fasteners 206 may include, for example, a first captive fastener 220 configured to extend through a first keyhole slot 222 and into the casing 202 and a second captive fastener 224 configured to extend through a second keyhole slot 226 and into the casing 202. In various embodiments, the first keyhole slot 222 extends through the cover 204 and includes a first engagement portion 228 and a first release portion 230. The first engagement portion 228 is configured to engage with a first head portion 232 of the first captive fastener 220 when the first captive fastener 220 is secured against the casing 202 (e.g., by tightly threading the first captive fastener 220 to the casing 202). Conversely, the first release portion 230 is configured to disengage with the first head portion 232 of the first captive fastener 220 when the first captive fastener 220 is unsecured against the casing 202 (e.g., by loosely threading the first captive fastener 220 to the casing 202).
In various embodiments, the first engagement portion 228 defines a characteristic dimension (e.g., a first engagement portion width or diameter 234) that is less than a characteristic dimension of the first head portion 232 (e.g., a first head portion diameter 236), while the first release portion 230 defines a characteristic dimension (e.g., a first release portion width or diameter 238) that is greater than the characteristic dimension of the first head portion 232. The characteristic dimension of the first engagement portion 228 being less than the characteristic dimension of the first head portion 232 enables the first captive fastener 220 to secure the cover 204 to the casing 202 when the first captive fastener 220 is secured against the casing 202. Conversely, the characteristic dimension of the first release portion 230 being less than the characteristic dimension of the first head portion 232 enables the cover 204 to be removed from the first captive fastener 220, as well as from the casing 202, when the first captive fastener 220 is unsecured against the casing 202.
In various embodiments, the second keyhole slot 226 extends through the cover 204 and includes a second engagement portion 240 and a second release portion 242. The second engagement portion 240 is configured to engage with a second head portion 244 of the second captive fastener 224 when the second captive fastener 224 is secured against the casing 202 (e.g., by tightly threading the second captive fastener 224 to the casing 202). Conversely, the second release portion 242 is configured to disengage with the second head portion 244 of the second captive fastener 224 when the second captive fastener 224 is unsecured against the casing 202 (e.g., by loosely threading the second captive fastener 224 to the casing 202). Similar to the description regarding the first keyhole slot 222, the second engagement portion 240 defines a characteristic dimension (e.g., a second engagement portion width or diameter) that is less than a characteristic dimension of the second head portion 244 (e.g., a second head portion diameter), while the second release portion 242 defines a characteristic dimension (e.g., a second release portion width or diameter) that is greater than the characteristic dimension of the second head portion 244. The characteristic dimension of the second engagement portion 240 being less than the characteristic dimension of the second head portion 244 enables the second captive fastener 224 to secure the cover 204 to the casing 202 when the second captive fastener 224 is tightly against the casing 202. Conversely, the characteristic dimension of the second release portion 242 being less than the characteristic dimension of the second head portion 244 enables the cover 204 to be removed from the second captive fastener 224, as well as being removed from the casing 202, when the second captive fastener 224 is unsecured against the casing 202.
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In various embodiments, the captive fastener 460 includes a blocking member 472 disposed at a distal end 474 (e.g., at a first distal end or a second distal end) of the threaded body 468. The blocking member prevents the captive fastener 460 from being removed from the casing 402 during removal of the cover 404 from the casing 402. In various embodiments, as illustrated in
Referring now to
In various embodiments, the step of releasing the first captive fastener includes unthreading the first captive fastener a first distance from the casing and releasing the second captive fastener includes unthreading the second captive fastener a second distance from the casing, wherein the first distance and the second distance are any distance sufficient to enable the cover to become unsecured to the casing and to readily slide away from the first captive fastener and the second captive fastener. In various embodiments, the first captive fastener may include a first blocking member configured to prevent the first captive fastener from being removed from the casing and the second captive fastener may include a second blocking member configured to prevent the second captive fastener from being removed from the casing.
Benefits, other advantages, and solutions to problems have been described herein with regard to specific embodiments. Furthermore, the connecting lines shown in the various figures contained herein are intended to represent exemplary functional relationships and/or physical couplings between the various elements. It should be noted that many alternative or additional functional relationships or physical connections may be present in a practical system. However, the benefits, advantages, solutions to problems, and any elements that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as critical, required, or essential features or elements of the disclosure. The scope of the disclosure is accordingly to be limited by nothing other than the appended claims, in which reference to an element in the singular is not intended to mean “one and only one” unless explicitly so stated, but rather “one or more.” Moreover, where a phrase similar to “at least one of A, B, or C” is used in the claims, it is intended that the phrase be interpreted to mean that A alone may be present in an embodiment, B alone may be present in an embodiment, C alone may be present in an embodiment, or that any combination of the elements A, B and C may be present in a single embodiment; for example, A and B, A and C, B and C, or A and B and C. Different cross-hatching is used throughout the figures to denote different parts but not necessarily to denote the same or different materials.
Systems, methods and apparatus are provided herein. In the detailed description herein, references to “one embodiment,” “an embodiment,” “various embodiments,” etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described. After reading the description, it will be apparent to one skilled in the relevant art(s) how to implement the disclosure in alternative embodiments.
Furthermore, no element, component, or method step in the present disclosure is intended to be dedicated to the public regardless of whether the element, component, or method step is explicitly recited in the claims. No claim element herein is to be construed under the provisions of 35 U.S.C. 112(f) unless the element is expressly recited using the phrase “means for.” As used herein, the terms “comprises,” “comprising,” or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.
Finally, it should be understood that any of the above described concepts can be used alone or in combination with any or all of the other above described concepts. Although various embodiments have been disclosed and described, one of ordinary skill in this art would recognize that certain modifications would come within the scope of this disclosure. Accordingly, the description is not intended to be exhaustive or to limit the principles described or illustrated herein to any precise form. Many modifications and variations are possible in light of the above teaching.
