Title of Invention	AN AXIAL THRUST PICK-UP DEVICE ADAPTED TO HYDRO MODEL TURBINES FOR DIRECT MEASUREMENT OF AXIAL THRUST ON THE RUNNERS INCLUDING THE BLADES OF THE TURBINES .
Abstract	An axial thrust pick-up device adapted to hydro model turbines for direct measurement of axial thrust on the runners including the blades of the turbines comprises an outercasing (7) having a groove configured at the bottom. A sensor means (1) disposed in the groove, atleast four strain gauges (5) disposed in diametrically opposed locations. A copper connector operably connects the atleast four strain gauges (5). The connector is passed through a hole (6) configured at the bottom of the outercasing (7). The ball bearing (3) accommodates the shaft (2) of the machine and is disposed on an upper groove of the sensor means (1). The runner (8) of the turbine connected at an end of the shaft (2) and a split nut (9) is located at a top end of the shaft (2) for accommodating the load of the turbine.

Title of Invention

AN AXIAL THRUST PICK-UP DEVICE ADAPTED TO HYDRO MODEL TURBINES FOR DIRECT MEASUREMENT OF AXIAL THRUST ON THE RUNNERS INCLUDING THE BLADES OF THE TURBINES .

Abstract

An axial thrust pick-up device adapted to hydro model turbines for direct measurement of axial thrust on the runners including the blades of the turbines comprises an outercasing (7) having a groove configured at the bottom. A sensor means (1) disposed in the groove, atleast four strain gauges (5) disposed in diametrically opposed locations. A copper connector operably connects the atleast four strain gauges (5). The connector is passed through a hole (6) configured at the bottom of the outercasing (7). The ball bearing (3) accommodates the shaft (2) of the machine and is disposed on an upper groove of the sensor means (1). The runner (8) of the turbine connected at an end of the shaft (2) and a split nut (9) is located at a top end of the shaft (2) for accommodating the load of the turbine.

Full Text	FIELD OF THE INVENTION The present invention generally relates to testing devices of hydro turbine models. More particularly, the invention relates to axial thrust pick-up device adapted to hydro model turbines for direct measurement of axial thrust on the runners including the blades of the turbines. BACKGROUND OF THE INVENTION In the manufacture of Hydro Generators, configuration of the Thrust Bearing(on which the whole machine is suspended) is a vital aspect. One of the main components, which contribute to an extremely large part of the load, is the downward thrust due to water pressure on the turbine. However, collecting data relating to the axial thrust of a hydro machine is a vital aspect of its design. This is done during turbine model testing. To get an estimate of this toad, during the testing of Hydro Turbine Models In an experimental stage,the thrust Is measured, and suitably scaled up to the prototype dimensions. Presently, the water thrust above and below the runner is measured using pressure gauges. To get the total load,the loads on the respective areas are then multiplied. The difference between the top and bottom loads is calculated to determine the resultant thrust However in this method, particularly in the case of Francis Turbines only the pressure on the top of the cunner can be measured. Pressure on the blades is difficult to measure and is assumed to be the same as the top of the runner. It is difficult to estimate the accuracy of such assumed measurement of the pressure on the blades. OBJECTS OF THE INVENTION Accordingly it is an object of the invention to propose an axial thrust pick-up device adapted to hydro model turbines for direct measurement of axial thrust on the runners Including the blades of the turbines which eliminates the disadvantages of the prior art Another object of the invention is to propose an axial thrust pick-up device adapted to hydro model turbines for direct measurement of axial thrust on the runners including the blades of the turbines which does not call for a separate measurement of the pressure below the runner of the turbine. A still another object of the invention is to propose an axial thrust pick-up device adapted to hydro model turbines for direct measurement of axial thrust on the runners including the blades of the turbines which is capable of directly measuring the total load on the thrust bearing. A further object of the invention is to propose an axial thrust pick-up device adapted to hydro model turbines for direct measurement of axial thrust on the runners including the blades of the turbines an axial thrust pick-up device adapted to hydro model turbines for direct measurement of axial thrust on the runners including the blades of the turbines which ensures sufficiency and linearity of the output data due to positioning of the sensors at variable locations being interconnected. SUMMARY OF THF INVENTION Accordingly there is provided an axial thrust pick-up device adapted to hydro model turbines for direct measurement of axial thrust on the runners including the blades of the turbines An axial thrust Pickup is made of stainless steel and is grooved at the bottom. A full Wheatstone Bridge is used to sense deformations due to loading. The shaft of the machine goes through the bearing and the Thrust pad of the machine is seated on the bearing . When the machine is running the toad on the bearing deforms the base of the sensor . The deformation causes a strain in the strain gauges . This strain in turn causes changes of resistance in the wheatstone bridge-which in turn gives rise to a voltage. This change in voltage is displayed on a digital indicator and is calibrated in kilograms. This gives a direct readout of the axial thrust of the machine is obtained. The device of the invention basically constitutes a strain-gauge based transducer which gives an output proportional to the deflection of the cylindrical support on which the thrust bearing is suspended. With a 1000 kg transducer the accuracy was checked and found to be within 1% of the full scale reading ie around 6 kg. The pressure below the runner was not required to be measured-as this reading gave the total load on the bearing. With the help of this system it is possible to determine the loading of the bearing and this data will be used to design the Thrust Bearing of the prototype. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS Figure 1- shows Pressure measurement above & below the Runner of a turbine Figure 2- shows an Axial Thrust Pickup device in a turbtne,according to the present invention. Figure 3- shows an exploded view of the Axial Thrust Pickup device of the Invention. Figure 4- shows the bottom side of the sensor of the device according to present invention. Figure 5- shows the device installed on a turbine. DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION The exploded view of the device is shown in Figure 2. A Sensor means (1) is made of stainless steel and is grooved at the bottom. In this groove atleast four strain gauges (5) are placed diametrically opposite and connected in a full Wheatstone Bridge configuration. (See Figure -4). A connecting cable is taken out through a hole (6) at the bottom of the sensor means (1). Varnish is coated over the strain gauges (5) and the connectors to prevent entry of moisture. The sensor Is then placed Into an outer casing (7). The upper side of the sensor means (1) is grooved to receive a Radial cum Axial Thrust Ball Bearing (3). Through the center of this bearing (3) the machine shaft (2) passes. The runner (8) is connected at the end of the shaft (2). The top of the shaft (2) has a split nut (9) which carries the whole toad of the turbine. When the machine is running the load on the bearing deforms the base of the sensor means (1). The deformation causes a strain In the strain gauges (5). This strain in turn causes changes of resistance in the wheatstone bridge-which in turn gives rise to a voltage. This change In voltage is displayed on a digital indicator and is calibrated in kilograms. This gives a direct readout of the axial thrust of the machine is obtained. The device comprises an outer casing (7) having a groove configured at the bottom. The sensor means (1) is disposed in the groove. The atleast four strain-gauges (5) are disposed in a diametrically opposed locations and operably connected via copper connectors to form a full wheatstone Bridge configuration. The ball bearing (3) is provided in an upper groove of the sensor means (1) so as to accommodate the shaft (2) of the machine. WE CLAIM 1. An axial thrust pick-up device adapted to hydro model turbines for direct measurement of axial thrust on the runners including the blades of the turbines, comprising: - an outercasing (7) having a groove configured at the bottom, a sensor means (1) disposed in the groove, atleast four strain gauges (5) disposed in diametrically opposed locations; - a copper connector operably connecting the atleast four strain gauges (5), the connector being passed through a hole (6) configured at the bottom of the outercasing (7); - a ball bearing (3) accommodating the shaft (2) of the machine and being disposed on an upper groove of the sensor means (1), the runner (8) of the turbine connected at an end of the shaft (2); and - a split nut (9) located at a top end of the shaft (2) for accommodating the load of the turbine. Characterized in that the said device is capable of directly measuring the total axial load on the thrust bearing through deformation of the base of the sensor which cause changes of resistance in the wheatsone bridge which produce a voltage, the change of voltage being diplayed on a digital indicator and is calibrated in kilograms. 2. An axial thrust pick-up device adapted to hydro model turbines for direct measurement of axial thrust on the runners including the blades of the turbines as claimed in claim 1 as substantially described and illustrated hereinwith reference to the accompanying drawings. An axial thrust pick-up device adapted to hydro model turbines for direct measurement of axial thrust on the runners including the blades of the turbines comprises an outercasing (7) having a groove configured at the bottom. A sensor means (1) disposed in the groove, atleast four strain gauges (5) disposed in diametrically opposed locations. A copper connector operably connects the atleast four strain gauges (5). The connector is passed through a hole (6) configured at the bottom of the outercasing (7). The ball bearing (3) accommodates the shaft (2) of the machine and is disposed on an upper groove of the sensor means (1). The runner (8) of the turbine connected at an end of the shaft (2) and a split nut (9) is located at a top end of the shaft (2) for accommodating the load of the turbine.

Full Text

FIELD OF THE INVENTION
The present invention generally relates to testing devices of hydro
turbine models. More particularly, the invention relates to axial
thrust pick-up device adapted to hydro model turbines for direct
measurement of axial thrust on the runners including the blades of
the turbines.
BACKGROUND OF THE INVENTION
In the manufacture of Hydro Generators, configuration of the Thrust
Bearing(on which the whole machine is suspended) is a vital aspect.
One of the main components, which contribute to an extremely large
part of the load, is the downward thrust due to water pressure on the
turbine.
However, collecting data relating to the axial thrust of a hydro
machine is a vital aspect of its design. This is done during turbine
model testing.
To get an estimate of this toad, during the testing of Hydro Turbine
Models In an experimental stage,the thrust Is measured, and suitably
scaled up to the prototype dimensions.

Presently, the water thrust above and below the runner is measured
using pressure gauges. To get the total load,the loads on the
respective areas are then multiplied. The difference between the top
and bottom loads is calculated to determine the resultant thrust
However in this method, particularly in the case of Francis Turbines
only the pressure on the top of the cunner can be measured.
Pressure on the blades is difficult to measure and is assumed to be
the same as the top of the runner. It is difficult to estimate the
accuracy of such assumed measurement of the pressure on the
blades.
OBJECTS OF THE INVENTION
Accordingly it is an object of the invention to propose an axial thrust
pick-up device adapted to hydro model turbines for direct
measurement of axial thrust on the runners Including the blades of
the turbines which eliminates the disadvantages of the prior art
Another object of the invention is to propose an axial thrust pick-up
device adapted to hydro model turbines for direct measurement of
axial thrust on the runners including the blades of the turbines which
does not call for a separate measurement of the pressure below the
runner of the turbine.

A still another object of the invention is to propose an axial thrust
pick-up device adapted to hydro model turbines for direct
measurement of axial thrust on the runners including the blades of
the turbines which is capable of directly measuring the total load on
the thrust bearing.
A further object of the invention is to propose an axial thrust pick-up
device adapted to hydro model turbines for direct measurement of
axial thrust on the runners including the blades of the turbines an
axial thrust pick-up device adapted to hydro model turbines for direct
measurement of axial thrust on the runners including the blades of
the turbines which ensures sufficiency and linearity of the output
data due to positioning of the sensors at variable locations being
interconnected.
SUMMARY OF THF INVENTION
Accordingly there is provided an axial thrust pick-up device adapted
to hydro model turbines for direct measurement of axial thrust on the
runners including the blades of the turbines
An axial thrust Pickup is made of stainless steel and is grooved at
the bottom. A full Wheatstone Bridge is used to sense deformations
due to loading. The shaft of the machine goes through the bearing
and the Thrust pad of the machine is seated on the bearing .

When the machine is running the toad on the bearing deforms the
base of the sensor . The deformation causes a strain in the strain
gauges . This strain in turn causes changes of resistance in the
wheatstone bridge-which in turn gives rise to a voltage. This change
in voltage is displayed on a digital indicator and is calibrated in
kilograms.
This gives a direct readout of the axial thrust of the machine is
obtained.
The device of the invention basically constitutes a strain-gauge based
transducer which gives an output proportional to the deflection of the
cylindrical support on which the thrust bearing is suspended.
With a 1000 kg transducer the accuracy was checked and found to
be within 1% of the full scale reading ie around 6 kg. The pressure
below the runner was not required to be measured-as this reading
gave the total load on the bearing.
With the help of this system it is possible to determine the loading of
the bearing and this data will be used to design the Thrust Bearing of
the prototype.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1- shows Pressure measurement above & below the Runner of
a turbine

Figure 2- shows an Axial Thrust Pickup device in a turbtne,according
to the present invention.
Figure 3- shows an exploded view of the Axial Thrust Pickup device
of the Invention.
Figure 4- shows the bottom side of the sensor of the device
according to present invention.
Figure 5- shows the device installed on a turbine.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF
THE INVENTION
The exploded view of the device is shown in Figure 2. A Sensor
means (1) is made of stainless steel and is grooved at the bottom. In
this groove atleast four strain gauges (5) are placed diametrically
opposite and connected in a full Wheatstone Bridge configuration.
(See Figure -4).
A connecting cable is taken out through a hole (6) at the bottom of
the sensor means (1). Varnish is coated over the strain gauges (5)
and the connectors to prevent entry of moisture. The sensor Is then
placed Into an outer casing (7).
The upper side of the sensor means (1) is grooved to receive a
Radial cum Axial Thrust Ball Bearing (3). Through the center of this
bearing (3) the machine shaft (2) passes. The runner (8) is

connected at the end of the shaft (2). The top of the shaft (2) has a
split nut (9) which carries the whole toad of the turbine.
When the machine is running the load on the bearing deforms the
base of the sensor means (1). The deformation causes a strain In the
strain gauges (5). This strain in turn causes changes of resistance in
the wheatstone bridge-which in turn gives rise to a voltage. This
change In voltage is displayed on a digital indicator and is calibrated
in kilograms.
This gives a direct readout of the axial thrust of the machine is
obtained.
The device comprises an outer casing (7) having a groove configured
at the bottom. The sensor means (1) is disposed in the groove. The
atleast four strain-gauges (5) are disposed in a diametrically opposed
locations and operably connected via copper connectors to form a full
wheatstone Bridge configuration. The ball bearing (3) is provided in
an upper groove of the sensor means (1) so as to accommodate the
shaft (2) of the machine.

WE CLAIM
1. An axial thrust pick-up device adapted to hydro model turbines for direct
measurement of axial thrust on the runners including the blades of the
turbines, comprising:
- an outercasing (7) having a groove configured at the bottom, a sensor
means (1) disposed in the groove, atleast four strain gauges (5) disposed
in diametrically opposed locations;
- a copper connector operably connecting the atleast four strain gauges (5),
the connector being passed through a hole (6) configured at the bottom
of the outercasing (7);
- a ball bearing (3) accommodating the shaft (2) of the machine and being
disposed on an upper groove of the sensor means (1), the runner (8) of
the turbine connected at an end of the shaft (2); and
- a split nut (9) located at a top end of the shaft (2) for accommodating the
load of the turbine.
Characterized in that the said device is capable of directly measuring the total
axial load on the thrust bearing through deformation of the base of the sensor
which cause changes of resistance in the wheatsone bridge which produce a
voltage, the change of voltage being diplayed on a digital indicator and is
calibrated in kilograms.

2. An axial thrust pick-up device adapted to hydro model turbines for direct
measurement of axial thrust on the runners including the blades of the
turbines as claimed in claim 1 as substantially described and illustrated
hereinwith reference to the accompanying drawings.

An axial thrust pick-up device adapted to hydro model turbines for
direct measurement of axial thrust on the runners including the
blades of the turbines comprises an outercasing (7) having a groove
configured at the bottom. A sensor means (1) disposed in the
groove, atleast four strain gauges (5) disposed in diametrically
opposed locations. A copper connector operably connects the atleast
four strain gauges (5). The connector is passed through a hole (6)
configured at the bottom of the outercasing (7). The ball bearing (3)
accommodates the shaft (2) of the machine and is disposed on an
upper groove of the sensor means (1). The runner (8) of the turbine
connected at an end of the shaft (2) and a split nut (9) is located at a
top end of the shaft (2) for accommodating the load of the turbine.

Documents:

680-KOL-2005-FORM 27.pdf

680-KOL-2005-FORM-27-1.pdf

680-KOL-2005-FORM-27.pdf

680-kol-2005-granted-abstract.pdf

680-kol-2005-granted-claims.pdf

680-kol-2005-granted-correspondence.pdf

680-kol-2005-granted-description (complete).pdf

680-kol-2005-granted-drawings.pdf

680-kol-2005-granted-examination report.pdf

680-kol-2005-granted-form 1.pdf

680-kol-2005-granted-form 18.pdf

680-kol-2005-granted-form 2.pdf

680-kol-2005-granted-form 3.pdf

680-kol-2005-granted-form 5.pdf

680-kol-2005-granted-gpa.pdf

680-kol-2005-granted-reply to examination report.pdf

680-kol-2005-granted-specification.pdf

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Patent Number

228377

Indian Patent Application Number

680/KOL/2005

PG Journal Number

06/2009

Publication Date

06-Feb-2009

Grant Date

04-Feb-2009

Date of Filing

28-Jul-2005

Name of Patentee

BHARAT HEAVY ELECTRICALS LIMITED

Applicant Address

REGIONAL OPERATIONS DIVISION (ROD), PLOT NO: 9/1, DJBLOCK 3RD FLOOR, KARUNAMOYEE, SALT LAKE CITY, KOLKATA-700091, HAVING ITS REGISTERED OFFICE AT BHEL HOUSE, SIRI FORT, NEW DELHI-110049

Inventors:

#	Inventor's Name	Inventor's Address
1	OM PRAKASH NAUTIYAL	HYDRO TURBNINE LAB., BHEL HARWDAR
2	AJAY KUMAR ARYA	HYDRO TURBNINE LAB., BHEL HARWDAR
3	DAYA NAND PANDEY	HYDRO TURBNINE LAB., BHEL HARWDAR
4	CHAMAN LAL CHHIBBA	HYDRO TURBNINE LAB., BHEL HARWDAR
5	SHREE CHAND	HYDRO TURBNINE LAB., BHEL HARWDAR

PCT International Classification Number

F03D 7/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA