Turbine rotor cover plate lock

A rotor assembly for a gas turbine engine includes a rotor configured for rotation about an engine axis, the rotor including an aft surface including a rotor slot and a cover plate attached to the aft surface of the rotor, the cover plate including a tab received within the rotor slot and a cover plate slot aligned with the rotor slot. A lock assembly disposed within the rotor slot holds a position of the cover plate relative to the rotor. The lock assembly includes a key portion conforming to the rotor slot, a lock portion engageable with a surface of the rotor slot and a threaded member for holding the lock assembly within the rotor slot.

BACKGROUND

In some engine turbine section configurations, a cover is secured to a side of a rotor. The cover is assembled through slots then rotated or clocked to secure the cover in place. The cover is typically heated during assembly, and then cooled once installed to provide an interference fit. In some configurations, an anti-rotation feature is utilized to prevent rotation of the cover. The anti-rotation features experience temperature variations along with circumferential forces during operation. Accordingly, it is desirable to design and develop anti-rotation features that are cost effective and provide a desired performance in the operational environment of a turbine rotor.

SUMMARY

A rotor assembly for a gas turbine engine according to an exemplary embodiment of this disclosure, among other possible things includes a rotor configured for rotation about an engine axis, the rotor including an aft surface including a rotor slot, a cover plate attached to the aft surface of the rotor, the cover plate including a tab received within the rotor slot and a cover plate slot aligned with the rotor slot. A lock assembly is disposed within the rotor slot for holding a position of the cover plate relative to the rotor. The lock assembly includes a key portion conforming to the rotor slot, a lock portion engageable with a surface of the rotor slot and a threaded member.

In a further embodiment of the foregoing rotor assembly, the rotor includes an aft wall defining the rotor slot and an annular channel forward of the aft wall, wherein the tab is received through the rotor slot and rotated circumferentially within the annular channel to align the rotor slot and the cover slot.

In a further embodiment of any of the foregoing rotor assemblies, the lock portion includes a barrel disposed about a central axis and a flange extending from the barrel, the barrel including threads configured to receive the threaded member.

In a further embodiment of any of the foregoing rotor assemblies, the flange extends parallel to the central axis.

In a further embodiment of any of the foregoing rotor assemblies, the flange engages an inner surface of the annular channel of the rotor to hold the locking assembly within the rotor slot.

In a further embodiment of any of the foregoing rotor assemblies, the key includes a lip contacting the aft surface of the cover plate.

In a further embodiment of any of the foregoing rotor assemblies, the flange of the lock is engageable to a portion of the key to prevent relative rotation therebetween.

In a further embodiment of any of the foregoing rotor assemblies, the key includes a window for viewing a position of the lock when assembled to the rotor slot.

A lock assembly for preventing movement between assembled structures according to an exemplary embodiment of this disclosure, among other possible things includes a key including a lip configured to engage an outside surface of one of the assembled structures. A lock includes a flange configured to engage an inner surface of the other of the assembled structures, and a fastening member configured to hold the lock and key in a fastened position.

In a further embodiment of the foregoing lock assembly, the lock comprises a barrel with an internal bore including threads corresponding to threads on the fastening member and a flange extending transverse to the bore.

In a further embodiment of any of the foregoing lock assemblies, includes a window.

In a further embodiment of any of the foregoing lock assemblies, the lip of the key defines a first contact surface and the flange defines a second contact surface spaced a distance from each other in a direction transverse to an axis of rotation of the fastening member.

In a further embodiment of any of the foregoing lock assemblies, the lock engages a portion of the key for controlling a position of the lock relative to the key.

A method of assembling a cover plate to a turbine rotor according to an exemplary embodiment of this disclosure, among other possible things includes inserting a tab of a cover plate through a rotor slot, rotating the cover plate to align a cover plate slot with the rotor slot, setting a locking assembly into an assembly orientation, inserting the locking assembly into the rotor slot to contact a key with an outer surface of one of cover plate, moving a lock of the locking assembly to a lock position, and tightening a fastener to engage the lock of the locking assembly within the rotor slot.

In a further embodiment of the foregoing method, includes tightening the fastener to engage the lock with an inner surface of the rotor and a lip of the key with the cover plate.

In a further embodiment of any of the foregoing methods, includes holding the assembly orientation of the lock relative to the key by contacting a portion of the lock with the key.

In a further embodiment of any of the foregoing methods, includes viewing a position of the lock through a window of the key for visually confirming a desired locking orientation of the lock.

Although the different examples have the specific components shown in the illustrations, embodiments of this invention are not limited to those particular combinations. It is possible to use some of the components or features from one of the examples in combination with features or components from another one of the examples.

DETAILED DESCRIPTION

A mid-turbine frame58of the engine static structure36is arranged generally between the high pressure turbine54and the low pressure turbine46. The mid-turbine frame58further supports bearing systems38in the turbine section28as well as setting airflow entering the low pressure turbine46.

In one disclosed embodiment, the gas turbine engine20includes a bypass ratio greater than about ten (10:1) and the fan diameter is significantly larger than an outer diameter of the low pressure compressor44. It should be understood, however, that the above parameters are only exemplary of one embodiment of a gas turbine engine including a geared architecture and that the present disclosure is applicable to other gas turbine engines.

Referring toFIGS. 2 and 3, the example turbine section28includes the rotors34. The aft most rotor34includes an aft surface62and a forward surface64. A cover plate68is assembled to the aft surface62of the rotor34. The cover plate68aids in holding a turbine blade66within the rotor34. The rotor34includes a rotor slot74and the cover plate68includes a cover plate slot78. Between the various cover plate slots78is a cover plate tab75(FIG. 4A-B). A lock assembly72prevents movement of the cover plate68relative to the rotor34.

Referring toFIGS. 4A-C, the example cover plate68is installed onto the rotor34by aligning tabs75with slots74and the rotor34. Cover blade68is then inserted through the rotor slots74such that the tabs75are disposed behind the slots74of the rotor34. The tabs75extend into the annular channel76(FIG. 3) that is disposed behind the slot74.

Referring toFIG. 4B, the cover plate68is then rotated in a direction of the arrow B to move the cover plate68towards a position where slots78of the cover plate68are aligned with slots74of the rotor34.

Referring toFIG. 4C, the cover plate68is shown where the cover plate slots78are aligned with rotor slots74to define an opening65. The opening65is defined partially by the rotor slot74and also partially by the cover plates slot78.

During assembly of the cover plate68to the rotor34, the rotor34is heated to expand it relative to the cover plate68. Once the cover plate68is inserted through the rotor slots74such that the rotor slot74and cover plate68are aligned to define the opening65the cover plate68is cooled. Upon cooling, an interference fit between the cover plate68and the rotor34is formed. The example lock assembly72is inserted within the openings65to prevent the cover plate68from rotating toward a direction away from the assembled position.

Referring toFIGS. 5A,5B,5C, the example lock assembly72includes a key80that has an opening86through which a fastening member96extends. In this example, the fastening member96is a threaded bolt. The threaded bolt96extends through the opening86defined in the key80. A threaded end100of the bolt96engages a lock88. The lock88includes a barrel90that has corresponding threads92to receive the threaded member96. The lock88also includes a flange portion94that extends from the barrel90. The flange94is configured to engage an inner portion of the rotor slot74and the key80includes a lip82that is configured to engage an outer surface70of the cover plate68.

Referring toFIG. 6, the example lock assembly72is shown installed within the opening65and includes the lip portions82of the key80engaged to the outer surface70of the cover plate68. The flange94of the lock88engages an inner surface of the annular channel76. The threaded member96engages the lock88and pulls the lock88such that the flange94is in contact with an interior surface of the annular channel76and the lip82is in contact with the outer surface70. Fastening member96is torqued such that the lock assembly72is held within the opening65during operation.

Referring toFIG. 7, the lock assembly72is shown in an assembly position102. In the assembly position102, the lock88is rotated about the axis98of the fastener96such that the flange94does not extend downwardly or outside of the key80periphery. This position allows the flange94and lock assembly72to be received within the opening65.

Referring toFIG. 8, the example lock assembly72is received within the opening65due to the lock88being set in the assembly position102(FIG. 7). As appreciated the lock88could be turned to either side so long as it is disposed within a periphery of the key80.

Referring toFIG. 9, a sectional view of the lock assembly72disposed within the opening65illustrates an initial position once received within the opening65. In the initial position, the flange94is still in the assembly position102where the flange94is disposed within a space defined by the periphery of the key80.

Referring toFIG. 10, the lock assembly72is disposed within the opening65such that the key80is recessed from the aft surface62of the rotor34. The recessed position of the lock assembly72reduces interruptions in the rotor surface that extend axially rearward of the rotor34.

Referring toFIG. 11, once the lock assembly72has been received within the opening65, the threaded member96is pushed along the axis98to allow the flange94to rotate from behind the key80. Rotation of the flange94of the lock88provides for the alignment of the flange94to engage an inner surface of the rotor annular channel76. The lip82of the key80engages the outer surface of the cover plate68. The fastener96is pushed into the annular channel76such that the lock portion88is pushed further into the rotor annular channel76. Accordingly, the lock88can be rotated about the axis98and placed in a position where it may contact the inner surface of the rotor annular channel76.

Referring toFIG. 12, further assembly is conducted by pulling the fastening member96along the axis98outwardly in a direction where the lock88and specifically the flange94is moved into contact with an inner surface of the rotor annular channel76. Once the flange94is engaged to the inner surface of the rotor annular channel76it engages a portion of the key80at an interface indicated at104. The interface104prevents rotation of the lock88and the flange94relative to the key80and away from the desired locking position.

The opening86in the key80provides a slip fit for the fastening member96such that it may be pulled along the axis98to move the lock88and the flange94between assembly and locking positions.

Referring toFIG. 13, the fastening member96is then tightened to draw the flange94against the inner surface of the rotor annular channel76. At the same time that the fastening member96is pulling the flange94against the inner surface of the annular channel76it is also moving the lip82into contact with the cover plate68.

The lock assembly72provides a first contact point defined by the flange94at a position below the axis98. The locking assembly72includes a second contact point where the lip82contacts the outer surface70of the cover plate68. Accordingly, the two contact points are spaced a distance apart from each other along the axis98and transverse to the axis98.

In this example, the flange94abuts an inner surface of the annular channel76while a lip82of the key80abuts an outer surface70of the cover plate68. The example lock assembly72is torqued to a desired torque to complete installation. The threads that are defined within the barrel section90of the lock88include an interference fit such that the threaded member96will not loosen due to vibratory or other operational conditions.

Referring toFIG. 14, a rear view from within the annular channel76illustrates the contact provided by the flange94. The example lock88is disposed in a specific orientation to provide the desired locking and securement of the lock assembly72within the opening65.

Referring toFIG. 15, to further assure proper installation of the example lock assembly72, the key80includes a window84through which the lock88can be viewed when fully assembled within the opening65. In this example, the lock88is shown through the window84at a slight angle. The example window84provides for visual verification that the lock88is positioned within acceptable tolerances and provides a verification that the lock88is engaged as required to an inner surface of the rotor annular channel76.

The disclosed example lock assembly72provides a securing function to prevent the rotation of the cover plate68towards a disassembly direction while also providing features that verify proper installation.