U.S. patent number 3,888,601 [Application Number 05/472,815] was granted by the patent office on 1975-06-10 for turbomachine with balancing means.
This patent grant is currently assigned to General Electric Company. Invention is credited to Larry Earl Glassburn.
United States Patent |
3,888,601 |
Glassburn |
June 10, 1975 |
TURBOMACHINE WITH BALANCING MEANS
Abstract
Means for balancing a turbomachine include a plurality of
balance weights made readily removable and replaceable from a rotor
wheel disc by providing opposed tang members extending from each
balance weight for slidably engaging mating grooves cut into
integral hook portions which overhang the periphery of the
disc.
Inventors: |
Glassburn; Larry Earl (Olean,
NY) |
Assignee: |
General Electric Company (Lynn,
MA)
|
Family
ID: |
23877047 |
Appl.
No.: |
05/472,815 |
Filed: |
May 23, 1974 |
Current U.S.
Class: |
416/144;
416/193A; 416/220R; 416/500 |
Current CPC
Class: |
F01D
5/027 (20130101); Y10S 416/50 (20130101) |
Current International
Class: |
F01D
5/02 (20060101); F01d 005/10 () |
Field of
Search: |
;416/144,145,500,219,221,215,218 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Powell, Jr.; Everette A.
Attorney, Agent or Firm: Johnson, Jr.; James W. Lawrence;
Derek P.
Claims
What is claimed is:
1. A turbomachine with means for balancing thereof comprising:
a rotating member having a plurality of circumferentially spaced
apart, generally axially, extending grooves disposed about the
outer periphery thereof;
a plurality of blade members having root and airfoil vane portions
wherein the root portions are received for retention within the
grooves;
a plurality of circumferentially spaced apart integral hook
portions extending from a side of the rotating member wherein each
integral hook portion has two opposed generally radially extending
sidewalls, each one of which is intersected by a generally radially
extending groove;
a plurality of balance weights each one of which has a pair of
longitudinal and transverse faces intersected by a top and bottom
face together with a pair of oppositely projecting tang members
wherein each tang member extends from an opposing longitudinal face
for engagement within a respective radially extending groove;
and
a snap ring for insertion between the hook portions and rotating
member for engagement with the bottom of the balance weights.
2. The turbomachine of claim 1 wherein the blade members include
platforms intermediate the airfoil vane portions and root portions
wherein the platforms generally overhang the root portions and
engage the tops of the balance weights so as to prevent outward
radial movement of the balance weights during centrifugal
loading.
3. The turbomachine of claim 2 wherein:
the generally axially extending grooves are of the dovetail type,
each having a pair of sidewalls, the inner ends of which are
undercut to provide longitudinally extending angled sidewalls which
operate as inwardly directed abutment faces, and
each blade root portion is thickened at the inner radial end to
provide outwardly extending shoulders with oppositely directed
longitudinally extending faces for respective engagement with the
longitudinally extending angled sidewalls of the axial grooves
wherein the two opposed generally radially extending sidewalls of
the integral hook portions are in general respective coplanar
alignment with the sidewalls of the blade receiving grooves.
4. The turbomachine of claim 3 wherein:
the rotating member comprises a rotor wheel disc having an enlarged
rim portion and a pair of oppositely directed faces;
each radially extending groove has an edge coincident with the
intersection between a sidewall of the axially extending groove and
a face of the rotor wheel disc; and
one edge of both of the opposed tang members of a balance weight is
coincident with a transverse end face of that balance weight.
5. The turbomachine of claim 2 wherein:
the top of the opposed tang members of each balance weight are
intersected by an oblique face extending between the top face and a
transverse end face of the balance weight;
and a transverse notch extends between the bottom of the opposed
tang members of each balance weight intersecting the same
transverse end face as well as the bottom face of the balance
weight such that the snap ring may engage the notch after the tangs
of the balance weight are inserted within the radially extending
grooves.
6. A balance weight for a turbomachine comprising a pair of
longitudinal and transverse faces intersected by a top and bottom
face together with a pair of oppositely projecting tang members
wherein each tang member extends from an opposing longitudinal
face.
7. The balance weight of claim 6 wherein one edge of both of the
opposed tang members is coincident with a transverse end face of
the balance weight.
8. The balance weight of claim 6 wherein:
the top of the opposed tang members of the balance weight are
intersected by an oblique face extending between the top face and a
transverse end face of the balance weight; and
a transverse notch extends between the bottom of the opposed tang
members of the balance weight intersecting the same transverse end
face as well as the bottom face of the balance weight.
Description
BACKGROUND OF THE INVENTION
This invention relates to a turbomachine with balancing means and,
more particularly, to a turbomachine which may be balanced by a
plurality of circumferentially spaced apart balance weights which
are easily removed and replaced.
As is well known in the art, all rotating machinery must be
balanced so that the effects of centrifugal force are uniformly
distributed around each rotating part. An unbalanced condition
within a revolving component may lead to severe vibration and
fretting, thus drastically reducing the useful life of the
component. Therefore, rotating components are generally balanced,
both dynamically and statically, by the addition of discrete
balance weights to the outer periphery thereof.
In turbomachinery of the axial flow type, there is generally
included a rotor wheel disc which supports a plurality of
circumferentially spaced apart rotor blades about the outer
periphery. Each of the blades includes an airfoil or vane section
through which fluid may flow for either compression or extraction
of work as is well known in the art. The blades may also include
root portions for insertion and retention within spaced apart
grooves disposed about the periphery of the rotor wheel disc. In
turbomachinery of this type, it is common practice to leave a space
between the bottom of the blade root and its associated groove for
the insertion of small balance weights. However, there are many
instances where due to the configuration of the surrounding
turbomachinery, it may prove impractical to insert small balance
weights in this manner because of the inability to readily remove
the rotor blades for replacement of the balance weights. Balance
weights may also be retained relative to a bolting circle around
the rotor wheel disc; however, this arrangement may also prove
impractical due to the inability to readily remove and replace the
balance weights.
Therefore, it is a primary object of this invention to provide a
simplified means of balancing a turbomachine wherein a plurality of
balance weights may be readily removed and replaced from a rotor
wheel disc regardless of the configuration of the surrounding
turbomachinery.
It is also an object of this invention to provide a simplified
means of balancing a turbomachine wherein a plurality of balance
weights may be attached to any rotor wheel disc design which
includes rotor blades with overhanging platforms as well as a snap
ring blade retainer.
SUMMARY OF THE INVENTION
These and other objects and advantages will be more clearly
understood from the following detailed description and drawings,
all of which are intended to be representative of, rather than in
any way limiting on, the scope of invention. The turbomachine of
this invention includes a balancing means and comprises a rotating
member having a plurality of circumferentially spaced apart,
generally axially, extending grooves disposed about the outer
periphery thereof. A plurality of blade members each include root
and airfoil vane portions wherein the root portions are received
for retention within the grooves. A plurality of circumferentially
spaced apart integral hook portions extend from the side of the
rotating member such that each integral hook portion has two
opposed generally radially extending sidewalls, each one of which
is intersected by a generally radially extending groove. A
plurality of balance weights are provided wherein each one of the
balance weights has a pair of longitudinal and transverse faces
intersected by a top and bottom face together with a pair of
oppositely projecting tang members wherein each tang member extends
from an opposing longitudinal face for engagement within a
respective radially extending groove. A snap ring is also provided
for insertion between the hook portions and the rotating member for
engagement with the bottom faces of the balance weights.
DESCRIPTION OF THE DRAWINGS
While the specification concludes with claims distinctly claiming
and particularly pointing out the invention described herein, it is
believed that the invention will be more readily understood by
reference to the discussion below and the accompanying drawings in
which:
FIG. 1 is a partial perspective view in cross-section of the
turbomachine and balancing means of this invention.
FIG. 2 is a partial cross-sectional view taken along the line 2--2
of FIG. 1.
FIG. 3 is a perspective view of a single balance weight as may be
used to balance the turbomachine of FIG. 1.
FIG. 4 is a side view of the balance weight of FIG. 3.
FIG. 5 is a top view of the balance weight of FIG. 3.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIGS. 1 and 2, there is shown in a partially
disassembled view a typical wheel blade assembly for rotating about
a central axis as may be utilized in an axial flow turbomachine
compressor, or in another type of axial flow turbomachine. In the
disclosed embodiment, the blade supporting structure comprises a
rotor wheel disc indicated generally at 10 having an enlarged rim
portion 12 and a pair of oppositely directed (axially of the rotor)
faces 14 and 16. Extending through the rim portion in a generally
axial direction relative to the rotor are a plurality of
circumferentially spaced apart blade receiving grooves indicated at
18. These grooves, which may be of the dovetail type, comprise a
pair of sidewalls 20, 21, the inner ends of which are undercut to
provide longitudinally extending angled sidewalls 22, 23, which
operate as inwardly directed abutment faces. The grooves also
include a wide base or bottom 24.
The rotor disc 10 includes a plurality of circumferentially spaced
apart rotor blades or vanes 26 disposed about its periphery. Each
of the rotor blades 26 includes an airfoil vane section 28 through
which gas may flow for either compression or extraction of work in
a manner well known to the art. The blades 26 include platforms 32
from which root portions 30 extend in substantially inward radial
directions wherein the platforms 32 generally overhang the root
portions. Each root portion 30 is thickened at the inner radial end
to provide outwardly extending shoulders with oppositely directed,
longitudinally extending, faces 34, 36. In addition, the root
portions 30 also include opposed transverse end faces 38, 40,
together with a bottom portion 42. The tables 28 are radially and
circumferentially retained in a conventional manner by axial
insertion of the root portions 30 within the blade receiving
grooves 18, such that the oppositely directed, longitudinally
extending, faces 34, 36 respectively engage the longitudinally
extending angled sidewalls 22, 23 of the blade receiving grooves.
As will be obvious from FIG. 1, the general overall shape of the
rotor wheel disc 10 or blade receiving grooves 18 corresponds to
the shape of the root portions 30 with a slight clearance between
the bottom portion 42 of the blade roots and the base 24 of the
grooves. Thus, the longitudinally extending faces 34, 36 of the
blade roots are shaped to abut and be retained against centrifugal
force by the longitudinally extending angled sidewalls 22, 23 of
the rotor wheel grooves 18. The means for retaining rotor blades
herein described is conventional and well known to the art.
Extending axially from the end face 14 of the rotor wheel disc 10,
are a plurality of circumferentially spaced apart integral hook
portions 44, each one of which includes a downwardly extending lip
portion 46 in spaced apart overlapping relation with the end face
14. Each integral hook portion 44 has two opposed generally
radially extending sidewalls 48, 50 in general respective coplanar
alignment with the sidewalls 20, 21 of the blade receiving grooves.
Each pair of opposed sidewalls 48, 50 is respectively intersected
by a pair of radially extending grooves 52, 54 for receipt of a
balance weight 56 in a manner to be more fully described in the
following discussion. The grooves 52, 54 are illustrated as having
one edge coincident with the intersection between the sidewalls 20,
21 and the rotor wheel disc face 14. However, it should be readily
apparent that the grooves do not necessarily have to be arranged in
this manner and may alternatively be spaced forward of the rotor
wheel disc face 14.
As is well known in the art, all rotating machinery must be
balanced so that the effects of centrifugal force become uniformly
distributed around each rotating component. An unbalanced condition
within a revolving component may lead to severe vibration and
fretting, thus drastically reducing the useful life of the
component. Therefore, rotating components are generally balanced,
both dynamically and statically by the addition of discrete balance
weights to the outer periphery thereof. In turbomachinery of the
type herein described, it is common practice to leave a space
between the base 24 of the blade receiving groove 18 and the bottom
portion 42 of the blade root 30 for the insertion of small balance
weights. As previously discussed, however, this means for balancing
turbomachinery may prove impractical due to the inability to
readily remove the rotor blades for replacement of the balance
weights. Other conventional means for balancing rotor wheel discs
in turbomachinery may depend upon access to a bolting circle which
may not always be possible to provide. In order to overcome these
prior art shortcomings, the balance weights of this invention have
been made readily removable and replaceable without having to first
remove the rotor blades or without requiring access to a bolting
circle.
Referring now to FIGS. 3 through 5, there is shown an enlarged view
of a single balance weight 56, which has two longitudinally
extending faces 58, 60, together with two opposed transverse end
faces 62, 64. The longitudinal and transverse faces are intersected
by a bottom face 66 and a top face 68 which respectively define the
inner and outer radial limits of the balance weight 56. A pair of
oppositely projecting tang members 70, 72 extend respectively from
the two longitudinally extending faces 58, 60, wherein the top of
the tang members 70, 72 are intersected by an oblique face 74. One
edge of each tang member 70, 72 is illustrated as being coincident
with the transverse end face 62; however, it should be readily
apparent that the tangs do not necesssarily have to be arranged in
this manner and may alternatively be spaced apart from the end face
62. A transverse notch 76 extends between the opposed tang members
70, 72 and intersects the transverse end face 62, together with the
bottom face 66.
After the individual rotor blades 26 have been inserted in their
respective grooves 18 in the aforementioned manner, each balance
weight is thereafter inserted between the integral hook portions 44
by first bringing the transverse end face 62 of the balance weight
into near engagement with the face 14 of the rotor wheel disc at a
position underlying the space between a pair of adjacent integral
hook portions. The balance weight 56 must then be circumferentially
aligned so that the tang members 70, 72 slidingly engage respective
grooves 52, 54 upon outward radial movement of the balance weight.
The balance weight 56 can then be pushed radially outward into
abutting engagement with the interior surface of the blade platform
32. In this manner, the balance weight 56 is retained from further
outward radial movement during centrifugal loading by engagement of
the top face 68 with the interior surface of the blade platform 32.
Axial movement is restrained by the engagement of the tangs 70, 72,
within the grooves 52, 54 while circumferential movement is
constrained by engagement of the two longitudinally extending faces
58, 60 between the radially extending sidewalls 48, 50.
A snap ring 78 must then be provided for insertion intermediate the
overlapping lip portions 76 of the integral hooks 44 and the face
14 of the rotor wheel disc 10. As is readily apparent, the top of
the snap ring 78 engages the top of the notch 76 thereby
restraining the individual balance weights 56 from moving radially
inward when the rotor wheel disc 10 is stationary. Thus, it will be
appreciated that the balance weights 56 may be removed and replaced
in an expeditious manner by simply removing the snap ring 78 and
thereafter sliding the balance weights radially inward out of
engagement with the groovess 52, 54. A new balance weight may
thereafter be inserted in like manner after which the snap ring 78
may be reinstalled in a conventional manner. Various numerical
weights may be provided for the balance weight 56 by simply
adjusting the length of the longitudinally extending faces 58, 60
as indicated by the dimension A.
As is readily apparent, the individual rotor blades are restrained
from forward axial translation out of the grooves 18 by the
engagement of the end faces 38 with respect to the transverse end
faces 62 of the balance weights. Rearward axial translation of the
individual rotor blades 26 out of their respective grooves 18 may
be restrained in a conventional manner by a second snap ring 82
engaged by a second integral hook portion 80 extending from the rim
portion 12.
Accordingly, while a preferred embodiment and a preferred
application of the present invention has been depicted and
described, it will be appreciated by those skilled in the art that
many modifications and changes may be made thereto without
departing from the invention's fundamental theme. For example, the
oblique surface 74 of the balance weight 56 may be eliminated along
with the notch 76 whereupon the bottom face 66 of the balance
weight would then be engaged by the top of the snap ring 78. Also,
it will be understood that the blade receiving grooves 18 may be
skewed in relation to the faces 14, 16 of the rotor wheel disc. In
like manner, the longitudinal faces 58, 60 of the balance weights
56 and the sidewalls 20, 21 of the integral hook portions 44 may
also be skewed in relation to a true radial plane and are hence
referred to as extending in only a general radial direction.
Therefore, having described a preferred embodiment of the
invention, what is desired to be secured by Letters Patent is as
follows.
* * * * *