U.S. patent application number 12/119653 was filed with the patent office on 2008-12-04 for anchorage system for the rotors of a rotating fluid machine.
Invention is credited to Giampaolo BERTONI, Massimo CAMATTI, Massimo PINZAUTI.
Application Number | 20080298971 12/119653 |
Document ID | / |
Family ID | 39745193 |
Filed Date | 2008-12-04 |
United States Patent
Application |
20080298971 |
Kind Code |
A1 |
PINZAUTI; Massimo ; et
al. |
December 4, 2008 |
ANCHORAGE SYSTEM FOR THE ROTORS OF A ROTATING FLUID MACHINE
Abstract
An anchorage system is described for a rotor (18) of a rotating
fluid machine (10). The rotor (18) has a profile which comprises a
first front surface (24) substantially concave and a second rear
surface (26) substantially convex, opposite to the first front
surface (24). The rotor (18) also has a central portion (28),
configured for being constrained with interference on a rotating
shaft (14) of the machine (10) and equipped with a shank (30)
connected with the second rear surface (26). The system comprises
at least one check ring (32) assembled by interference on the shank
(30) of the rotor (18). The check ring (32) has a first internal
circumferential surface (34), coupled by interference with the
shank (30), and a second internal circumferential surface (36),
coupled by interference with the shaft (14), to increase the torque
which can be transmitted from the shaft (14) to the rotor (18).
Inventors: |
PINZAUTI; Massimo;
(Florence, IT) ; CAMATTI; Massimo; (Pistoia,
IT) ; BERTONI; Giampaolo; (Udine, IT) |
Correspondence
Address: |
General Electric Company;GE Global Patent Operation
PO Box 861, 2 Corporate Drive, Suite 648
Shelton
CT
06484
US
|
Family ID: |
39745193 |
Appl. No.: |
12/119653 |
Filed: |
May 13, 2008 |
Current U.S.
Class: |
416/204R |
Current CPC
Class: |
F04D 29/266
20130101 |
Class at
Publication: |
416/204.R |
International
Class: |
F04D 29/34 20060101
F04D029/34 |
Foreign Application Data
Date |
Code |
Application Number |
May 30, 2007 |
IT |
MI 2007 A 001100 |
Claims
1. An anchorage system for a rotor (18) of a rotating fluid machine
(10), said rotor (18) having a profile which comprises a first
front surface (24) substantially concave and a second rear surface
(26) substantially convex, opposite to the first front surface
(24), a central portion (28) of said rotor (18), configured for
being constrained with interference on a rotating shaft (14) of
said machine (10) and being equipped with a shank (30) connected
with said second rear surface (26) of said rotor (18), wherein it
comprises at least one check ring (32) assembled by interference on
said shank (30) of said rotor (18), said check ring (32) having a
first internal circumferential surface (34), coupled with
interference with said shank (30), and a second internal
circumferential surface (36), coupled with interference with said
shaft (14), to increase the torque which can be transmitted from
said shaft (14) to said rotor (18).
2. The system according to claim 1, wherein said first internal
circumferential surface (34) has a larger diameter with respect to
said second internal circumferential surface (36).
3. The system according to claim 2, wherein between the outer
surface of said shaft (14) and said second internal circumferential
surface (36) of said check ring (32), one or more keys (38) are
inserted to increase the interference between the parts and boost
the transmissibility of the torque from said shaft (14) to said
rotor (18).
4. The system according to claims 1 or 2, wherein the ratio between
the external diameter (D.sub.e) of said shank (30) and the diameter
(D) of said shaft (14) is within the range of 1.10 and 1.25.
5. The system according to claims 1 or 2, wherein the ratio between
the external diameter (D.sub.a) of said check ring (32) and the
diameter (D) of said shaft (14) is within the range of 1.40 and
1.60.
6. The system according to claims 1 or 2, wherein the ratio between
the length (L.sub.c) of said shank (30), measured along the axial
direction of said shaft (14), and the diameter (D) of said shaft
(14) is within the range of 0.25 and 0.35.
7. The system according to claims 1 or 2, wherein the ratio between
the length (L.sub.a) of said second internal circumferential
surface (36), measured along the axial direction of said shaft
(14), and the diameter (D) of said shaft (14) is within the range
of 0.40 and 0.70.
8. A rotating fluid machine (10) comprising an anchorage system for
a rotor (18) according to any of the previous claims.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an anchorage system for the
rotors of a rotating fluid machine and, more specifically, to an
anchorage system between a rotor and rotating shaft of a compressor
of the centrifugal type.
[0003] 2. Background of the Invention
[0004] It is known that a compressor is a machine capable of
raising the pressure of a compressible fluid (gas) with the use of
mechanical energy. Among the various types of compressors used in
industrial process plants, so-called centrifugal compressors can be
mentioned, in which the energy is supplied to the gas in the form
of centrifugal acceleration due to the rotation, generally driven
by a driver (electric motor or vapour turbine), of an organ called
rotor or turbine wheel.
[0005] Centrifugal compressors can be provided with a single rotor,
in the so-called single-phase configuration, or with several rotors
situated in series, in this case called multiphase compressors.
More specifically, each phase of a centrifugal compressor normally
consists of a suction duct for the gas to be compressed, a rotor,
which is capable of providing the gas with kinetic energy, and a
diffuser, whose function is to convert the kinetic energy of the
gas leaving the rotor into pressure energy.
[0006] The rotors of centrifugal compressors are generally in the
form of a disk in the central part of which there is a hub capable
of supporting a varying number of vanes. The hub is equipped with a
central pass-through hole which allows the rotor to be constrained,
normally by wedging, to the rotating shaft of the centrifugal
compressor.
[0007] One of the problems which arise with rotors of the known
type, especially if made of light metallic alloys (for example
aluminum) rather than steel in order to be able to operate with
particular fluids, is maintaining a sufficient interference with
the shaft during the functioning of the compressor. Maintaining an
adequate interference between the rotor or rotors and the shaft
during the functioning of the machine is in fact a necessary
condition for maintaining the equilibrium of the rotor and
transmitting the torque required by the work energy of the rotor
itself, from the shaft to the rotor. This second aspect is above
all particularly critical for rotors fitted onto the shaft. The
radial dilation of the rotor hub, especially if made of an aluminum
alloy, due to thermal dilation and also to the effect of
centrifugal forces, is in fact extremely high with respect to the
same end-products made of steel, consequently facilitating the
total or partial loss of interference, and in any case insufficient
for transmission of the torque.
[0008] In particular, rotors made of light aluminum alloy cannot be
simply fitted onto the shaft, as these aluminum alloys have a low
elastic modulus, which corresponds to a low rotor hub-shaft
specific contact pressure and a high thermal dilation coefficient,
which causes a major loss in interference during the functioning of
the rotor. At present, the only known application of rotors made of
aluminum envisages their fitting onto the head of the shaft, i.e.
at the end of the compressor shaft, where the centering system and
transmission of the torque is extremely facilitated.
BRIEF SUMMARY OF THE INVENTION
[0009] One of the advantageous features of the subject matter
disclosed herein is therefore to solve the problems relating to the
rotors according to the known art, by providing an anchorage system
for the rotors of a rotating fluid machine and, more specifically,
an anchorage system between a rotor and the rotating shaft of a
compressor of the centrifugal type, suitable for guaranteeing the
transmission of power by interference between shaft and rotor,
especially in the case of the use of rotors made of aluminum
alloys.
[0010] A further advantageous feature of the invention is to
provide an anchorage system for the rotors of a rotating fluid
machine which allows the assembly of rotors made of aluminum alloys
also along the shaft of a compressor of the multiphase type and not
only in correspondence with one of its ends, guaranteeing adequate
centering and torque transmission.
[0011] These advantageous features according to the present
invention are achieved by providing anchorage systems for the
rotors of a rotating fluid machine, these rotors having a profile
which comprises a first front surface substantially concave and a
second rear surface substantially convex, opposite to the first
front surface, a central portion of the rotor configured for being
constrained with interference on a rotating shaft of the machine
and being equipped with a shank connected with the second rear
surface of said rotor, these system further including at least one
check ring assembled by interference on the shank of the rotor, the
check ring having a first internal circumferential surface, coupled
with interference with the shank, and a second internal
circumferential surface, coupled with interference with the shaft,
to increase the torque which can be transmitted from the shaft to
the rotor.
[0012] Further details of the invention are indicated in the
subsequent claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The characteristics and advantages of an anchorage system
for the rotors of a rotating fluid machine according to the present
invention will appear more evident from the following illustrative
and non-limiting description, referring to the enclosed schematic
drawings, in which:
[0014] FIG. 1 is a partial sectional view of a generic multiphase
centrifugal compressor, equipped with a series of rotors fitted
onto the shaft between two supporting bearings;
[0015] FIG. 2 is a sectional schematic view of the anchorage system
for the rotors of a rotating fluid machine according to the present
invention; and
[0016] FIG. 3 is another sectional schematic view of the anchorage
system for the rotors of a rotating fluid machine according to the
present invention, in which some fundamental magnitudes are
indicated.
DETAILED DESCRIPTION OF THE INVENTION
[0017] With reference in particular to FIG. 1, this shows a generic
centrifugal compressor, of the multiphase type, indicated as a
whole with the reference number 10. The compressor 10 comprises a
casing or stator 12 in which a shaft 14 is rotatingly assembled,
which rests on a series of supporting bearings 16. A series of
rotors 18 is fitted onto the shaft 14, each of which equipped in
turn with a series of circumferential vanes 20 having a
substantially radial development. Channels or diaphragms 22 are
situated on the casing 12, which allow the compressible fluid (gas)
to be sent towards a first phase and, from this, to the subsequent
phases to be then expelled, under pressure, from the compressor
10.
[0018] With reference to FIG. 2, this is a sectional view of a
single rotor 18, preferably made of aluminum alloy and assembled on
the shaft 14 with interference, analogously to what occurs with the
more common steel rotors.
[0019] The rotor 18 has a profile which comprises a first front
surface 24, substantially concave, and a second rear surface 26,
substantially convex, opposite to the first front surface 24.
[0020] The central portion 28, commonly called "hub", of the rotor
18 and configured for being constrained with interference to the
shaft 14 of the compressor 10, is equipped with a shank 30 having a
suitable length, connected with the rear surface 26 of the rotor 18
itself.
[0021] According to the invention, a check ring 32 having two
distinct internal circumferential surfaces 34 and 36 with a
different diameter, is assembled by interference on the shank 30 of
the rotor 18. The first circumferential surface 34, having a larger
diameter, is coupled with interference with the external diameter
D.sub.e (FIG. 3) of the shank 30, whereas the second
circumferential surface 36, having a smaller diameter, is coupled
with interference directly onto the shaft 14. In this way, an
increase in interference can be obtained, which is generated
between the external diameter of the shank 30 and the check ring
32, during the functioning of the compressor 10.
[0022] In order to increase the interference between the parts and
boost the transmissibility of the torque from the shaft 14 to each
rotor 18, one or more keys 38 are preferably inserted between the
outer surface of the shaft 14 and the second inner surface 36 of
the check ring 32, as shown in FIG. 2.
[0023] In order to further increase the torque which can be
transmitted from the shaft 14 to the rotor 18, the check ring 32
can also be applied onto the front side of the rotor 18, i.e. in
correspondence with the eye 40 of the rotor 18 itself.
[0024] On the basis of experimental tests and controls on the
efficiency of the compressor 10, it was found that the ratios of
the diameter D of the shaft 14 with the external diameter D.sub.e
of the shank 30 are fundamental, and also with the external
diameter D.sub.a of the check ring 32 and with the lengths L.sub.c
and L.sub.a, measured along the axial direction of the shaft 14,
which respectively represent the effective length of the shank 30
and the length of the second surface 36, or effective length of the
check ring 32 (see FIG. 3).
[0025] A good compromise between dimensions, tensions and
efficiency has been obtained with the following ratios, referring
to the diameter D of the shaft 14:
D c D = 1.10 / 1.25 D a D = 1.40 / 1.60 L c D = 0.25 / 0.35 L a D =
0.40 / 0.70 ##EQU00001##
[0026] As the check ring 32 extends in length, in the axial
direction of the shaft 14, in addition to the shank 30 of the rotor
18, as shown in FIGS. 2 and 3, in order to respect the axial
encumbrances or, in other words, the pitch of the rotors 18 in the
multiphase compressor 10, the check ring 32 itself can be equipped
with a portion 42 of its outer surface suitably shaped in
correspondence with the diaphragms 22, increasing the diameter of
the interphase labyrinth seals.
[0027] It can thus be seen that the anchorage system for the rotors
of a rotating fluid machine, in particular between a rotor and the
rotating shaft of a compressor of the centrifugal type, according
to the present invention, achieves the purposes previously
specified. The system in fact allows the necessary torque to be
transmitted from the shaft to the rotors even if these are made of
light alloy (aluminum alloys), and also maintains the centering of
the same rotors on the shaft of the machine, eliminating the danger
of inducing disequilibrium on the rotor during the functioning of
the compressor.
[0028] The anchorage system for the rotors of a rotating fluid
machine of the present invention thus conceived can in any case
undergo numerous modifications and variants, all included in the
same inventive concept; furthermore, all the details can be
substituted by technically equivalent elements. In practice, the
materials used, as also the forms and dimensions, can vary
according to technical demands.
[0029] The protection scope of the invention is therefore defined
by the enclosed claims.
* * * * *