FIELD OF INVENTION
The present invention relates to an intermediate sleeve ring in exhaust hood supported
bearings of a turbo-generator. More particularly, the invention relates to a sleeve ring
housing the drive end bearing of the rotor to make bearings of both ends identical to
achieve interchangeability.
BACKGROUND OF THE INVENTION
Turbo-generator is supported by a bearing at each end of the rotor to transmit load and
vibrations to foundation. The bearings are either end-shield mounted or pedestal
mounted, depending on the machine design chosen. The front or turbine end bearing
is also called as drive end bearing and rear bearing as non-drive end bearing. The type
of support and the bearing shell employed on both ends is normally identical, whether it
is end shield mounted or pedestal mounted.

When coupled to specific turbines, it is necessary to locate the generator front bearing
in the turbine exhaust hood. This bearing shall hence be designed to match with the
internal contours of exhaust hood. In view of this, the congruence between the
generator front and rear bearing is lost and as per the prior art, the bearings are
different from one another. Customers are required to order for two bearings
separately for any future requirements. The present invention is to achieve congruence
of bearings used on front end and rear end, front end matching with the exhaust hood
internals at the same time. An intermediate sleeve ring is invented to achieve the
above. The outer surface of the sleeve matches with the inner contour of exhaust hood
and inner with the outer surface of the bearing shell.
OBJECTS OF THE INVENTION
It is therefore an object of the invention to propose an intermediate sleeve ring in
exhaust hood of a rotor of a turbo-generator which reduces the customers spares
requirement, eliminates increase in casting variety, reduces manufacturing cycle time in
view of standardization, eliminates variety in other bearing accessories like bearing
seals, jack oil flexible pipes, vibration monitoring instrumentation etc.

SUMMARY OF THE INVENTION
In order to provide identical bearing at drive end and non-drive end of a rotor of a
turbo-generator, an intermediate sleeve ring (11) is invented and provided in the
exhaust hood (2) of the rotor. The sleeve ring (11) has its outer dia matching with the
internal contours of the exhaust hood (2) while the inner dia matching with the outer
dia of the bearing shell (4). The inner periphery of the ring (11) is spherically milled to
allow the bearing sphere to swivel during operation. The inner ring (11) is placed
between the exhaust hood (2) and bearing shell (4). The present invention thus
enables the use of identical bearings at drive or front end and non-drive or rear end of
a rotor.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The invention can now be described in detail with the help of the figures of the
accompanying drawings in which
Figure 1 shows arrangement of generator rotor on bearing supports as per prior
art.

Figure 2 shows the generator rotor on bearing supports as per the invention.
Figure 3 shows the details of intermediate sleeve ring.
Figure 4 shows the seating arrangement of bearing shell inside the exhaust as per
the present state of the art.
Figure 5 shows the bearing assembly inside exhaust hood as per present invention.
DETAILED DESCRIPTION OF THE INVENTION
In Figure 2 the schematic diagram of a typical bearing assembly inside the turbine
exhaust hood (2) is shown. The generator rotor (5) is supported at its front side by
drive end bearing shell (4) and at rear side by non-drive end bearing shell (9). These
bearing shells are in turn are supported by separate pedestals (8). In some of the
designs, the generator drive end bearing is placed in the turbine exhaust hood (2).
This arrangement makes the length of overall shaft train compact and keeps the
operating speed away from the rotor critical speeds.

The bearing shell (4) as per the prior art shown in Figure 1 is provided with a
rectangular groove (13) to accommodate the intermediate ring (11). This arrangement
requires use of a bearing on drive side different from the shell used on non-drive end.
The assembly of rotor (5) as per the invention is shown in Figure 2. As per the
invention, an intermediate sleeve ring (11) is devised that is sandwiched between
exhaust hood (2) and the bearing shell (4). This makes it possible to use a bearing
shell on drive end (4) that is identical to bearing shell employed on non-drive end (9).
The design of the intermediate sleeve ring (11) is shown in Figure 3. As shown in
Figure 5 the inner periphery of the ring (11) is spherical milled (12) to allow the bearing
sphere to swivel during operation as per the rotor operational catenaries.
The assemblies of bearing shell (4) as per the present state of the art and as per the
present invention inside the exhaust hood (2) are shown in Figures 4 and 5. While the
present state of the art as in Figure 4 envisages a stepped type of groove in the outer
surface of bearing shell, for facilitating locating in the exhaust hood (2), the bearing
shell (4) as per invention as shown in Figure 5 proposes a spherically milled outer
contour. The shell (4) seats in a sleeve (11) located in the exhaust hood (2) and whose
internal surface is milled spherical (12). The external surface of the sleeve

(11) is made cylindrical that fits in a groove turned inside the exhaust hood (2). The
ring is made in two halves. The top half of the sleeve ring (11) is bolted to the bottom-
parting plane of the exhaust hood (2). The ring holds the bearing shell (4) on its outer
periphery. Hence, the ring holds the drive-end bearing (4) which is identical to non-
drive end bearing (9).
The present trend in the bearing design is to have a spherical contour on the shell
periphery that ensures continuous bearing alignment with the shaft catenaries in all
regimes of operation. Hence, the non-drive end is designed with this spherical surface.
The grooved bearing shell on one side that is on drive end and spherically milled outer
periphery for the other side make the individual shell designs different. This puts the
customer at a disadvantage in view of the increased variety of components and
additional efforts and investment for spares procurement and storage.
The invention will make the bearing shells same on both ends, hence, the
disadvantages indicated above are eliminated.
WE CLAIM
1. An intermediate sleeve ring to achieve interchangeability of bearings in exhaust
hood supported bearings of a turbo generator comprising:
an intermediate sleeve ring (11) located in turbine exhaust hood (2) and made in
two halves;
the top half of the sleeve ring (11) being bolted to the exhaust hood (2);
the ring (11) holding the bearing shell (4) on its outer periphery;
wherein the said ring sitting on the inner periphery of the exhaust hood (2);
characterised in that the internal surface of the ring (11) is provided with a
milled spherical surface (12) matching the contour of the spherically milled outer
periphery of drive end bearing (4) when the external surface of the said ring is
made cylindrical to fit in a groove (14) in the exhaust hood (2).
2. An intermediate sleeve ring in exhaust hood supported bearings of a turbo
generator as claimed in claim 1, wherein the drive end bearing being held by the
sleeve ring (11) is identical to non-drive end bearing (9).
3. An intermediate sleeve ring in exhaust hood supported bearings of a turbo
generator as claimed in claim 1, wherein the spherical contour (12) of inner
surface of ring (11) and outer periphery of the front drive end bearing (4) allows
said bearing to swivel during operation.