FIELD OF INVENTION
The present invention relates to an arrangement of oil flow control for shell
type hydro turbine guide bearing. More particularly the invention relates to an arrangement
for ensuring sufficient oil supply to bearing at very low shaft speeds during starting and
during shut down and also relates to providing an adjustment of oil flow rate to achieve
optimum oil temperature.
BACKGROUND OF THE INVENTION
Guide bearing of a vertical axis hydro turbine absorbs the hydraulic and
mechanical unbalance loads. A shell type guide bearing comprises of a steel cylindrical shell
the inside of which is lined with White metal/ Babbit metal. The bearing shell (01) bears
against the cylindrical journal portion of the shaft (07) with a clearance through which oil
flows. The oil film not only lubricates but also extracts the bearing heat.
In a shell type guide bearing, oil circulation through the bearing is maintained
by an oil scraper type pump (11), which pumps hot oil from lower reservoir (22) to an oil
cooler (12) mounted above the bearing cover (04). The oil thus cooled in the cooler, flows
into its upper oil reservoir (23) from where it flows down through bearing, back into the
lower reservoir.
The lower oil reservoir is in the form of a cylindrical tank, which is fixed to the
shaft flange at lower end through a bolted connection. When the lower oil reservoir / oil
slinger (20) rotates along with shaft, the oil mass (08) also rotates along with it and takes
shape of a parabola. The shape of the parabolic mass of rotating oil changes with speed of

turbine. As the turbine picks -up speed, the oil mass moves towards outer diameter and
moves up. The rotating oil when it reaches the suction opening of the oil scraper (11) it
gets pumped and reaches the cooler, where it gets cooled and returns back to the lower
reservoir through the bearing.
During start - up the whole process of oil spinning in the form of parabola,
reaching oil scraper, getting pumped to cooler installed above bearing cover, flowing back
to turbine bearing through upper reservoir; may sometimes take so much time that the
turbine guide bearing may get burnt. Also there is no adjustment for oil flow to achieve
optimum / desirable bearing oil temperature; nor is there any arrangement to conveniently
and accurately set the angular position of the scraper type oil pump.
This invention is about an arrangement which takes care of the drawbacks
viz. that of ensuring sufficient oil supply to bearing at low speeds during start - up and
shut down, provision to adjust oil flow rate to achieve optimum oil temperature and
arrangement to conveniently and accurately set the oil scraper type pump.
OBJECTS OF THE INVENTION
It is therefore an object of the invention to propose an arrangement of oil
flow control for shell type hydro turbine guide bearing which is capable of ensuring a
reliable and sufficient circulation of oil at low speeds during start up and shut down.
Another object of the invention is to propose an arrangement of oil flow
control for shell type hydro turbine guide bearing which ensures adjustment of oil
circulation through shell type guide bearing to control the optimum temperature of oil and
oil level in the upper reservoir.

A further object of the invention is to propose an arrangement of oil flow control
for shell type hydro turbine guide bearing which ensures an accurate and convenient
setting of oil scrapper arrangement.
SUMMARY OF THE INVENTION
In a shell type hydro turbine bearing with rotating oil sump (08), oil is
pumped from lower reservoir (22) to upper reservoir (23) by an arrangement of oil scraper
(11). The oil scraper converts centrifugal force of rotating oil into pressure head thereby
conveying oil from lower reservoir to upper reservoir through a cooler (12) mounted on the
bearing cover.
Since quantum of oil circulation is a function of speed, sometime there are
issues of bearing getting heated up or burnt, at low speeds during starting or stopping.
To avoid such mishaps this innovation comprises of additional oil scrapers
(09) the suction and discharge ends of which are set at much lower levels than the
conventional oil scraper, thereby ensuring that oil circulation starts at lower speeds and the
bearing is not starved of oil. In addition to the above, a motor operated gear pump (02); is
installed over the bearing cover, to suck oil from the lower oil reservoir to the upper oil
reservoir. Starting/ stopping of the motor operated gear pump is controlled by level
electrodes (19) thereby ensuring a minimum oil level in the upper oil reservoir for safe
operation of the bearing. This invention also proposes an arrangement for accurate and
convenient setting of angular position of oil scrapper which is essential for good pumping
and hence good oil circulation.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Fig. 1 - shows the elevation view of the arrangement of oil flow control for shell type
hydro turbine guide bearing according to the prior art.
Fig. 2 - shows the plan view of the arrangement of oil flow control for shell type
hydro turbine guide bearing according to the prior art.
Fig. 3 - shows a general arrangement sketch in a standstill condition according to the
present invention.
Fig. 4 - shows a plan view as per section AA of the arrangement according to the
invention.
Fig. 5 - shows the setting of scrapper using screws as per the invention.
Fig. 6 - shows pumping of oil at start of turbine from starting and intermediate
scrapper according to the invention.
Fig. 7 - shows initial filling of upper sump before machine start up using pump
according to the invention.
Fig. 8 - shows pumping of oil at rated RPM from high level scrapper according to the
invention.
Fig. 9 - shows a setting fixture.
Fig. 10 - shows an angular setting piece.
Fig. 11 - shows an oil scrapper
Fig. 12 - shows pumping of oil through oil grooves during starting of machine

Fig. 13 - shows oil flow control arrangement
Fig. 14 - setting fixture arrangement for angular setting of oil scrappers
Fig. 15 - additional views showing setting fixture arrangement
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION
In the prior art arrangement the oil scraper (pump) performed well at the
rated speed, but at low speeds at start-up and shut downs it was not sure whether the
head generated would be enough to push the oil up to the cooler. In certain cases by the
time the oil pumped could force its way through the cooler and come back to the bearing,
the bearing used to get heated up and burn.
In the present invention, the solution to this problem has been made and the
drawbacks/limitations have been addressed by incorporation of the following arrangement.
As shown in Fig. 3, a motor driven gear pump (02) is disposed in the
arrangement with its suction pipe (06) placed inside the lower oil reservoir (22). The gear
pump (02) sucks oil from the lower oil reservoir (22) through gear pump suction pipe (06)
and pumps the oil to the upper oil reservoir (23) up to a certain level before the turbine is
given a start command.
A level electrode (19) / relay interlock, as shown in fig. 7 ensures that the
turbine does not start before the oil level in the upper oil reservoir (23) reaches a certain
pre-defined level that ensures a positive circulation of oil which is a prerequisite for safety
of bearing.

a) VERY LOW LEVEL OIL SCRAPER (09)
As shown in fig. 3, a low level oil scrapper pump (09) is installed at a very low
level in the lower oil reservoir (22) to suck oil from the low speed parabolic oil mass to a
level just above the mounting level of the bearing shell (01). The pumped oil comes out
into the upper oil reservoir through holes in oil scrapper (09) and angular setting piece
(14). This oil which has been pumped up enters the bearing through holes in the flange of
bearing shell (01) and lubricates the bearing.
The oil scraper is meant to circulate oil through bearing at very low speeds
during start up and stopping and its suction point is placed at a very low level of the
parabolic rotating oil mass. Along the length of oil scraper there are radial holes at the level
of flange of bearing shell (01). These oil holes ensure positive circulation of oil through
bearing within seconds of start of turbine. At the top open end of the scraper an oil flow
control arrangement is provided. By this control arrangement the amount of oil flow
through the holes and through the top can be adjusted during commissioning. If required
the oil flow from the top can be totally stopped by tightening the disc of oil controller (18)
on top of the scraper, and locked using lock nut (24), as shown in fig. 13.
b) NORMAL RUNNING OIL SCRAPPER (11)
A high level oil scrapper pump (11) is installed at a high level in the lower oil
reservoir (22), as shown in fig. 3 and fig. 6 to pump oil from the high speed parabolic oil
mass to a level above the coolers (12) in the upper reservoir (23) supported over bearing
housing (05).
This scrapper suction is placed at the highest level amongst the three
scrapers and its discharge end is connected to a shell and tube type cooler (25) placed
either on the bearing cover or tangentially to the bearing housing as shown in fig. 4 and
fig. 8.

c) INTERMEDIATE LEVEL OIL SCRAPPER (13)
Also, as shown in fig. 3 and fig. 6, an intermediate level oil scrapper (13) is
installed in between high level oil scrapper (11) and low level oil scrapper (09) to pump oil
from the lower oil reservoir (22) which ensures adequate circulation of oil during the long
coasting down periods during shut down.
Along the length of the oil scrapper there are radial hole at the level of flange
of bearing shell. This scrapper is also provided with an oil flow control arrangement at the
top end. By this control arrangement the amount of oil flow through the scrapper can be
adjusted.
An oil flow control arrangement (18) shown in fig. 6, comprising of a screw
arrangement is provided above all the 3 oil scrapper type pumps to control the oil
discharge through the three scrappers (09, 11 and 13) to adjust the oil levels in the upper
and lower oil reservoirs (23, 22). The oil flow control arrangement (18) for shell type hydro
turbine guide bearing comprises of a disc above the outlet opening of oil scrappers (09, 11,
13) whose position can be adjusted by a mechanism and locked in the optimum position.
The oil flow control arrangement (18) includes above mentioned two
additional oil scrappers (09, 13) other than the conventional one (11) whose suction end
and discharge end are located at a lower level than the conventional oil scrapper (11) so
that oil is pumped to the upper reservoir (23) at lower speeds.
SETTING OF OIL SCRAPPER AT SITE
Since in the normal assembly procedure, the radial gap between the oil
scrapper outer tip and ID of the slinger cannot be checked due to accessibility constraint,
performance of oil scrapper is very much dependent on angular position. This innovation
proposes a setting fixture (21) for accurately setting the angular position of oil scrapper.

The process of setting the oil scrapper consists of assembling the bearing housing and
bearing shell on setting fixture (21) which replicates the oil slinger (20). An angular setting
piece (14) is provided for accurate angular setting of the oil scrapper which is required for
good pumping performance.
The oil scrapper setting, as shown in fig. 14 and 15 comprises of an
arrangement to accurately and conveniently set the oil scrapper for proper oil pumping.
This arrangement comprising of angular setting piece (14), guide pin (15) fixed to oil
scrapper in upper reservoir and the position of guide pin being arrested by 2 set
screws/nuts (17) fixed using tack welded lugs (16) to upper oil reservoir.
A setting fixture is used to ascertain that the arrangement is verified before
actual installation.
DETAILS OF REFERENCE NUMERALS:-
1. GUIDE BEARING SHELL
2. GEAR PUMP
3. GEAR PUMP DISCHARGE PIPE
4. BEARING COVER
5. BEARING HOUSING
6. GEAR PUMP SUCTION PIPE
7. TURBINE SHAFT
8. ROTATING OIL
9. OIL SCRAPPER (STARTING AND COASTING DOWN)

10. TURBINE HOUSING
11. HIGH LEVEL OIL SCRAPPER
12. OIL COOLER
13. INTERMEDIATE LEVEL OIL COOLER
14. ANGULAR SETTING PIECE

15. GUIDE PINS
16. LUGS
17. SCREWS & NUTS
18. OIL FLOW CONTROLLER
19. LEVEL ELECTRODES
20. OIL SLINGER
21. SETTING FIXTURE
22. LOWER RESERVOIR
23. UPPER RESERVOIR
24. LOCK NUT
25. SHELL & TUBE TYPE COOLER

WE CLAIM
1. An arrangement of oil flow control for shell type hydro turbine guide bearing
comprising;
disposing a motor driven gear pump (02) with its suction pipe (06) placed inside
the lower oil reservoir (22);
installing a high level oil scrapper pump (11) at a high level in the lower oil
reservoir (22) to pump oil from the high speed parabolic oil mass to a level
above the coolers (12) in the upper reservoir (23);
sucking oil from the lower oil reservoir (22) through gear pump discharge pipe
(06) to the upper oil reservoir (23) to a certain predefined level ensured by a
level electrode (19) to provide a positive circulation of oil for the bearing (01);
wherein
a low level oil scraper pump (09) is installed at a very low level in the lower oil
reservoir (22) to suck oil from the low speed parabolic oil mass to a level just
above the mounting level of the bearing shell (01) when the pumped oil being
moved into the upper oil reservoir (22) through holes in oil scrapper (08) and
angular setting piece (14) allowing the pumped oil to enter the bearing through
holes in the flange of bearing shell (01) to lubricate the bearing; and
an intermediate level oil scrapper (13) is installed in between high level oil
scrapper (11) and low level oil scrapper (09) to pump oil from the lower oil
reservoir (22) to ensure adequate circulation of oil during the long coasting down
periods during shut down; wherein,
an oil flow control arrangement (18) is disposed above all the three oil scrapper
type pumps (09, 11, 13) to control the oil discharge through the said three
scrappers to adjust the oil levels in the upper and lower oil reservoirs (23, 22)
when position of the said scrappers can be adjusted by a mechanism disposed in
the said oil flow control arrangement.
when the angular setting piece provides accurate angular setting of the oil
scrapper required for good pumping and good circulation of oil.

2. An arrangement as claimed in claim 1, wherein the angular setting piece is
provided to set accurate angular setting of the oil scrapper to ensure good
pumping performance.
3. The arrangement as claimed in claim 1, wherein the level electrode / relay
interlock (19) is disposed in the arrangement to ensure that the turbine does not
start before the oil level in the upper oil reservoir (23) reaches a certain
predefined level.

ABSTRACT

A motor driven gear pump is disposed in the arrangement to suck oil from the lower
reservoir (22) to upper reservoir (23) upto a certain level before the turbine starts. A low
level oil scraper pump (9) is installed at a very low level to suck oil just above the mounting
level of the bearing shell (01). This oil lubricates the bearing. A high level oil scrapper
pump is installed at a high level in the lower oil reservoir (22) to pump oil above the
coolers (12) in the upper reservoir (23). An intermediate level oil scrapper (13) is installed
to pump oil from the lower oil reservoir (22) from a level which is in between the high and
low level oil scrappers (09 and 11). This oil ensures adequate circulation of oil during shut
down.