FIELD OF INVENTION
The present invention relates to wind turbines. The present invention
particularly relates to a device for applying emergency brake to protect the
wind turbines catastrophic failures in the event of other protection mechanisms
fail to respond.
More particularly, the present invention relates to a device for emergency
stoppage of a horizontal axis wind turbines by applying emergency brake, in an
event of disengagement of gears in the gearbox.
BACKGROUND OF THE INVENTION
Wind turbines are used to convert wind energy into electrical energy. Wind
turbine consists of a generator, a gearbox, a bearing house, a hub and a
plurality of blades placed in a nacelle. The nacelle is installed on top of a tower.
Wind turbine blades convert the wind energy into mechanical energy resulting
in slow rotation of rotors with high torque. This low-speed high torque is
converted into high speed-low torque through the gearbox. The generator
coupled to the gearbox produces electrical power. A set of disc brakes on the
high speed-low torque side of the gearbox is used to stop the wind turbines as
and when required. The wind turbines start rotating once a cut-in-speed is
reached, the cut-in speed being the minimum wind speed above which the
wind turbine will produce power. The wind turbines stop rotating once a cut-
out speed is reached, the cut-out speed being the maximum wind speed above
which the wind turbine will be stopped. The cut-out speed represents a design
factor and is an important safety parameter to be continuously monitored.
Once the cut-out

speed is reached, the wind turbine's controller transmits a series of instructions
causing the wind turbine to prevent catastrophic failures. One of the important
steps initiated by the controller is to apply brake to the high-speed side of the
gearbox to completely stop the machine. However this step of present art is not
a fail-safe condition, particularly if the gears of the gearbox are broken and
mechanically disengaged. In the event of such a failure, the mechanical
connectivity to transmit brake-power is lost. Consequently the braking power
cannot be used to stop the wind turbine leading to rotation of the turbine rotor
at very high speed, which will result in catastrophic failures including loss of
resources.
OBJECTS OF THE INVENTION
It is therefore, an object of the present invention to propose a device for
emergency stoppage of wind electric turbines by applying emergency brake on
the high-torque, low-speed side of the gearbox in an event of disengagement of
gears of the gearbox, which eliminates the disadvantages of the prior art.
Another object of the present invention is to propose a device for emergency
stoppage of wind electric turbines by applying emergency brake on the high-
torque, low-speed side of the gearbox in an event of disengagement of gears of
the gearbox, which is economic, simple and easy to maintain.
SUMMARY OF THE INVENTION
Accordingly, there is provided a device for emergency stoppage of a wind electric
turbine, the turbine comprising a generator, a gearbox, a bearing housing, a hub

for mounting of plurality of blades, and a plurality of blades, a main shaft of the
gearbox having a flange for mounting the hub, an output shaft of the gearbox
operably connected to the generator. The device comprises: a brake - lever fixed
at an interim location onto the bearing housing so as to form a rigid swivelable
member. The brake-lever has a swivelable brake pad at a first end, a thrust pin
being swiveably disposed at a second end of the brake - lever. A spring is
disposed below the brake - lever such that in a passive condition of the device,
the brake pad remains frictionally detached from the flange. A hydraulic power
pack is arranged which is actuable by an external power source in response to an
emergency command from the operator of the turbine. The hydraulic power pack
on actuation exerts an upward pressure to the thrust pin, the upward pressure
causing the brake pad when transmitted via the brake - lever to engage with the
flange to generate anti-rotational frictional force for stopping the rotations of the
turbine blades thereby effecting emergency stoppage of the turbine.
According to the present invention, in the event of gears in the gearbox are
broken and due to this, the braking system in the high speed side is not effective
and / or there is a need to apply emergency brake for stopping the wind turbine
then the device mounted on the low speed side of the gearbox applies
emergency brake stops the wind turbine blades from rotating.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING
Figure 1 - Shows a schematic device for carrying out the present invention.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF
THE PRESENT INVENTION
The present invention is described herein below with reference to Figure - 1. As
shown in Figure - 1, the wind electric turbine comprises a generator (14), a
gearbox (01), a bearing housing (15), a hub for blade mounting (11), a plurality
of blades (12) placed in a nacelle. The gearbox (01) having a main shaft (02)
with a flange (03) for mounting of the hub (11). The gearbox (01) having an
output shaft (10) coupled to the generator (14). A fulcrum bracket (07) is
disposed on the bearing housing (15). A main braking means (13) is provided on
a high-speed side of the turbine.
The device having a brake lever (06) fixed onto the bearing housing (15) at an
interim location with a plurality of fastening members so as to form a rigid swivel
- able member. One end of the brake lever (06) having a swivel - able brake
pad (04) and the other end having a swivel - able thrust pin (08). A spring (05)
below the brake lever (06) keeps aside the brake pad (04) from rubbing onto the
flange (03) in non-brake condition. A hydraulic power pack (09) placed below the
thrust pin (08) is secured by the plurality of fastening members on the bearing
housing (15). The hydraulic power pack (09) is actuated by an external
uninterrupted power source on a command from the wind turbine operator. On
actuation, the hydraulic power pack (09) will exert upward pressure to the thrust
pin (08) and the upward pressure is further transmitted through the brake lever
(06) to the brake pad (04), which in turn initiates stopping of the blades (12) by
means of friction between the brake pad (04) and the flange (03).

We Claim:
1. A device for emergency stoppage of a horizontal axis wind turbine, the
turbine comprising a generator (14), a gearbox (01), a bearing housing
(15), a hub (11) for mounting of plurality of blades (12), and a plurality of
blades (12), a main shaft (02) of the gearbox (01) having a flange (03)
for mounting the hub (11), an output shaft (10) of the gearbox (01)
operably connected to the generator (14), the device comprising:
- a brake lever (06) fixed at an interim location onto the bearing housing
(15) so as to form a rigid swivelable member, the brake-lover (06) having
swivelable brake pad (04) at a first end, a thrust pin (08) being swiveably
disposed at a second end of the brake-lever (06);
- a spring (05) disposed below the brake lever (06) such that in a passive
condition of the device, the brake pad (04) remains frictionally detached
from the flange (03);
- characterized in that the hydraulic power pack (09) actuable by an
external power source in response to an emergency command from the
operator of the turbine, the said hydraulic power pack (09) on actuation
for exerting an upward pressure to the thrust pin (08), the upward
pressure causing the brake pad (04) when transmitted via the brake lever
(06) to engage with the flange (03) for generating anti-rotational friction
force for stopping the rotations of the turbine blades (12) thereby
effecting emergency stoppage of the turbine.

2. The device as claimed in claim 1, wherein the brake lever (06) is fixed on
the bearing housing (15) by means of a plurality of fastening members.
3. The device as claimed in claim 1, wherein the hydraulic pack (09) is fixed
on the bearing housing (15) by means of a plurality of fastening means.
4. The device as claimed in claim 1, wherein a main braking means (13) is
provided on a high-speed side of the turbine and wherein the emergency
device is actuated when the main braking means (13) becomes
inoperative.

ABSTRACT

A DEVICE FOR EMERGENCY STOPPAGE OF A HORIZONTAL AXIS WIND
TURBINE
A device for emergency stoppage of a horizontal axis wind turbine, the turbine
comprising a generator (14), a gear box (01), bearing housing (15) a hub (11)
for mounting of plurality of blades (12), and a plurality of blades (12), a main
shaft (02) of the gearbox (01) having a flange (03) for mounting the hub (11),
an output shaft (10) of the gearbox (01) operably connected to the generator
(14), the device comprising:
a brake lever (06) fixed at an interim location on to the bearing housing (15)
having a swivelable brake pad (04) at a first end, a thrust pin (08) disposed at
a second end of the brake lever (06), a spring (05) disposed below the brake
lever (06) such that in passive condition, the brake pad (04) remains frictionally
detached from the flange (03) wherein a hydraulic power pack (09) actuable by
an external power source in response to emergency command exerts upward
pressure to thrust pin (08) for causing brake pad (04) to engage with flange
(03) for effecting emergency stoppage of the turbine.