System and method to retain a turbine cover plate with a spanner nut

Patent metadata

Field	Value
Publication number	US-2017114650-A1
Application number	US-201514922844-A
Country	US
Kind code	A1
Filing date	Oct 26, 2015
Priority date	Oct 26, 2015
Publication date	Apr 27, 2017
Grant date	—

Abstract

In accordance with some embodiments of the present disclosure, a gas turbine engine is presented. The engine has at least one turbine stage and each stage has a turbine disc concentric with the axis of the engine. The turbine disc has a turbine arm positioned axially from the disc and rigidly attached thereto. The drive arm is also concentric with the turbine axis and has an outer surface. The turbine stage also has a cover plate concentric with the turbine axis and covering at least a portion of the turbine disc. An arrangement of turbine blades are positioned around the periphery of the disc and are retained on the turbine disc at least partially by the cover plate. The system includes a spanner nut, and threads on a portion of the turbine drive arm. The spanner nut it threaded onto the turbine arm which applies an axial force on the cover plate, thereby retaining the cover plate.

First claim

What we claim is:

1 . A gas turbine engine having at least one turbine stage, each stage having a turbine disc, said turbine disc being concentric with an axis of the gas turbine engine and having a turbine drive arm positioned axially from the turbine disc and rigidly attached there-to, said drive arm concentric with the axis and having an outer surface; the at least one turbine stage having a cover plate concentric with the axis and covering the turbine disc, the turbine stage further including an arrangement of turbine blades positioned around the periphery of the turbine disc and concentric with the axis and retained on the turbine disc at least in part by the cover plate, comprising:
a spanner nut, threads on a portion of the turbine drive arm; wherein the spanner nut is threaded onto the turbine arm and applies an axial force on the cover plate to retain the cover plate.

2 . The gas turbine engine of claim 1 , wherein the spanner nut further comprises a relative rotation restriction feature preventing relative rotation with the turbine disc, wherein the feature is selected from the group consisting of a dimpled surface, a scalloped surface and a facet and a slot.

3 . The gas turbine engine of claim 1 , wherein the cover plate comprises a first end and a second end, the first end proximate the turbine disc arm and the second end in contact with a turbine disc rim face, the cover plate extending from the turbine disc drive arm to a the rim face of the turbine disc.

4 . The gas turbine engine of claim 3 , wherein the cover plate comprises an axial stop extending radially inward from the first end in physical contact with the spanner nut.

5 . The gas turbine engine of claim 3 , wherein the turbine disc rim face comprises a plurality of turbine disc pilot tabs on the turbine disc rim face and engaged by the second end of the cover plate.

6 . The gas turbine engine of claim 1 , wherein the cover plate comprises a resilient material.

7 . The gas turbine engine of claim 6 , wherein the cover plate is a material selected from the group consisting of nickel, cobalt, Nickel/cobalt alloy and titanium.

8 . The gas turbine engine of claim 1 , wherein the cover plate is a full face cover plate.

9 . The gas turbine engine of claim 1 , wherein the cover plate is a partial face cover plate.

10 . The gas turbine engine of claim 1 , wherein the threads are buttress thread.

11 . A turbine assembly comprising:
a turbine disc having a center axis and a radially outer rim; a turbine disc arm coaxial with the turbine disc and extending axially from the disc and having a portion threaded; a turbine cover plate having a first end and a second end and coaxial with the turbine disc, a spanner nut coaxial with the turbine disc and threaded on to the turbine disc arm; wherein the spanner nut is in contact with the first end of the turbine cover plate and holds the second end in contact with the outer rim.

12 . The turbine assembly of claim 11 , wherein the outer rim comprises an arrangement of plural turbine blade inserts, the arrangement coaxial with the disc, said second end of the cover plate restricting axial movement of the plural turbine blade inserts.

13 . The turbine assembly of claim 11 , wherein the outer rim comprises a plurality of turbine disc pilot tabs, the pilot tabs in contact with the second end of the cover plate and restricting radial movement of the second end.

14 . The turbine assembly of claim 11 , wherein the cover plate comprises an axial stop extending radially inward from the first end and engaging the spanner nut.

15 . The turbine assembly of claim 11 , further comprising a relative rotation locking device preventing relative rotation of the spanner nut with the turbine disc arm, wherein the relative rotation locking device is selected from the group consisting of locking plates, retaining rings, tangs, lugs and keys.

16 . The turbine assembly of claim 15 , wherein the spanner nut further comprises a feature complementary of the relative rotation locking device wherein the feature is selected from the group consisting of a dimpled surface, a scalloped surface and a facet and a slot.

17 . In a gas turbine engine having an axis and a turbine disc and a cover plate for the turbine disc, wherein the turbine disc is coaxial with the axis, the turbine disc including an arm extending axially from the turbine disc, the turbine disc also including a rim around a periphery of the turbine disc, wherein the cover plate defines at a first and second end concentric openings, each opening with a radius greater than a radius of the arm, a method of retaining the cover plate comprising:
threading the arm of the turbine disc to produce a threaded arm; moving the cover plate in an axial direction such that the arm is within the openings; positioning the second end of cover plate proximate the rim of the turbine disc; applying a rotation to a spanner nut to thread the spanner nut onto the threaded arm; wherein the rotation is coaxial with the axis. contacting, with the spanner nut, the cover plate and applying a force via the contact with the cover plate, to retain the second end against the rim,

18 . The method of claim 17 , wherein the rim further comprises a plurality of pilot tabs and the second end is retained against the plurality of pilot tabs.

19 . The method of claim 17 , wherein the step of contacting, with the spanner nut, the cover plate further comprises extending an axial stop radially inward from the first end of the cover plate and contacting with, the spanner nut, the axial stop.

20 . The method of claim 17 , wherein the force is predetermined and corresponds to the rotation of the spanner nut.

Assignees

• Rolls Royce Corp

Inventors

• Snyder Brandon R

Classifications

• F05D2240/15

  Heat shield · CPC title

• F01D5/066

  Connecting means for joining rotor-discs or rotor-elements together, e.g. by a central bolt, by clamps · CPC title

• F01D5/082

  on the side of the rotor disc · CPC title

• F05D2260/31

  Retaining bolts or nuts · CPC title

• F01D5/3015 Primary

  with side plates · CPC title