Rotor assembly cover plate

1. A rotor assembly comprising:

a rotor disk concentric with an axis of rotation having a plurality of axially-extending keyways arranged around the outer circumference of the disk, wherein each of the axially-extending fir tree keyways defines a plurality of axially extending recesses;

a plurality of blade assemblies, each of the plurality of blade assemblies comprising a blade, a blade skirt, and a fir tree blade key; the blade skirt positioned between the blade and the fir tree blade key; each fir tree blade key having a shape including a plurality of axially extending, circumferentially oriented blade key ridges, the shape being complimentary to a respective fir tree keyway of the plurality of fir tree keyways of the rotor disk and received in the respective fir tree keyway such that each of the respective blade assemblies of the plurality of blade assemblies are restrained from relative movement in the radial and circumferential directions, wherein each fir tree blade key defines an axial notch extending a full circumferential width of the fir tree blade key and part of a radial height of the fir tree blade key; and,

a plurality of cover plate segments; each of the plurality of cover plate segments forming a respective portion of an annular cover plate ring concentric with the axis of rotation, each of the plurality of cover plate segments having a front plate face and a back plate face each normal to the axis and having a thickness in the axial direction less than the radial width of each segment, the front and back plate face having a radially outer portion, radially inner portion, and a plate key extending from the front plate face of the cover plate segment that is received in a portion of the respective fir tree keyway at the axial notch of the respective fir tree blade key, wherein the plate key comprises a shape including a plurality of axially extending, circumferentially oriented plate key ridges, the shape being complimentary to a portion of a respective fir tree keyway of the plurality of fir tree keyways of the rotor disk corresponding to the axial notch in the respective fir tree blade key, wherein the plate key ridges axially align with the axially extending, circumferentially oriented blade key ridges and engage with corresponding axially extending recesses of the respective fir tree keyway, and wherein the plate key extends less than a full radial length of the respective fir tree keyway;

wherein, each front plate face of the plurality of cover plate segments engage one or more of the respective blade keys and the radially outer portions engage a blade groove defined by the blade skirt and the radially inner portions engage a disk groove in the disk restricting relative axial movement of the blade assembly with respect to the rotor disk; and the plate key engages the portion of the fir tree keyway restricting radial movement of the cover plate segment.

2. The rotor assembly of claim 1 , wherein the plurality of axially-extending recesses in each keyway and the plurality of complimentary axially-extending ridges of each blade key correspond to each other.

3. The rotor assembly of claim 1 , wherein the blade key comprises a radially inner portion with an axial length less than the axial extent of the keyway.

4. The rotor assembly of claim 3 , wherein the plate key has an axial length less than or equal to the axial extent of the keyway.

5. The rotor assembly of claim 1 , wherein the plate key engages the blade key.

6. The rotor assembly of claim 1 , wherein the number of the plurality of cover plate segments is equal to the number of the plurality of keyways.

7. A cover plate for maintaining axial alignment between a blade assembly and a rotor disk comprising:

a plurality of flat arcuate segments, each segment having an outer portion and inner portion with respect to a radial direction, and a forward surface normal to an axial direction defined by the arcuate segment; and

a key extending in the axial direction from the forward surface, the key configured to be received within a fir tree keyway defined in the rotor disk for retaining the blade assembly at an axial notch of a fir tree blade key that is also received within the fir tree keyway, wherein the plate key comprises a shape including a plurality of axially extending, circumferentially oriented plate key ridges, the shape being complimentary to a portion of the fir tree keyway of the rotor disk corresponding to the axial notch in the fir tree blade key, wherein the plate key ridges are configured to axially align with axially extending, circumferentially oriented blade key ridges and engage with corresponding axially extending recesses of the fir tree keyway, and wherein the plate key is configured to extend less than a full radial length of the fir tree keyway.

8. The cover plate of claim 7 , wherein the key has an axial width less than the axial width of the keyway proximate the key.

9. The cover plate of claim 7 , wherein each of the segments have keys.