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Патент USA US2407455

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Sept. 10,1946.
‘2,407,454
‘ P. w; SEEWER’
AUTOMATIC SPEED LIMITING DEVICE FOR HYDRAULIC TURBINE ROTORS
Filed Dec.‘ 28; ‘1942
3 sheetsfsheet l
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2,407,454
AUTOMATIC SPEED'LIMI'I‘ING DEVICE FOR HYDRAULIC TURBINEROTORS
\Filed 06¢ 28, 1942
a Sheets-Sheet 2~
~
Sept. AUTOMATIC
10,
SPEED LIMITINGv
'
P.
DEVICESEEWER
FOR HYDRAULIC TURBINE
' _
ROTORSI
Fil'ed Dec. 28, '1942
_
'
:s Sheets-Sheet ‘s
Patented Sept. 1Q, 1946
' '
2,407,454
UNITED STATES PATENT; OFFICE
AUTOMATIC SPEED LIMITING DEVICE FOR
HYDRAULIC TURBINE ROTORS '
Paul Werner Seewer, Rugby, England, assignor to
The English Electric, Company Limited, ‘Lon
don, England, a British company
Application December 28, 1942, Serial No. 470,396
In Great Britain January 12, 1942
screams. (01. 253-7443)
.1
This invention relates to hydraulic turbines and
has for its object to prevent automatically ex
cessive runaway speeds. Although of general
application it is of particular value when applied
to turbines having swivelling propeller type blades
a
2
vertical shaft 4 terminating in the hollow hub 5
carrying the swivelling blades 6.
Secured to the. hub immediately above the
blades 6 is the ring 1 incorporating the automatic
speed-limiting device according to the invention.
Within this ring are mounted a number of brak
ing vanes 8 each of which is hinged as shown in
Figs. 1 and 3 about a hinge pin 9 ,with its axis in
difficult.
,
a plane transverse to the rotor axis. Normally
The invention consists in speed-limiting means
each of the vanes 8 is retained in the position
mounted on the turbine rotor and adapted, if a 10
shown in full lines so as to be exactly flushwith
predetermined speed be exceeded, to project into
since as is Well known the problem of guarding
against runaway of such turbines is particularly
the curved circumferential surface of the ring 1
the stream and limit the speed of the rotor by
which is a smooth continuation of the surface of
exerting a braking torque thereon or by diverting
the hub 5. vWhen under the action of centrifugal
or otherwise disturbing the water on its way to
the driving blades or by having a combination of 15 force these vanes turn about their pivot pins 9
the water vpressure——as soon as the tips of the
these effects.
vanes emerge-assists the vanes to fly out. In
Preferably, the device according to the inven
their outer position, the vanes 8 create a disturb
tion consists of a speed-limiting unit in the form
‘ ing action on the incoming stream thereby‘re
of a ring fastened to- the hub of the turbine rotor
ducing the driving torque exerted by the water
adjacent to and preferably above the turbine
on the turbine driving blades while at the same
blades. Hinged or slidably mounted on or within
this ring are braking or de?ecting vanes or like
members normally retained against the action of
time these vanes 8 can exercise a powerful brak
ing torque on the rotor by reason of their having
to act against the incoming water stream.
centrifugal force and held out of the stream.
Although the device is e?ective if the vanes 8
When a certain speed is exceeded centrifugal 25
be parallel to the rotor axis, the drawings show
force causes these members to project into the
the axes of the hinge pins 9 inv planes which,
stream.
,
although transverse to the rotor axis, are not
One form of the invention is .illustrated by
horizontal but inclined at an angle other than
Figures 1-4 and Figures 6 and '7 of‘the accom
panying drawings, of which Figure 1 is the left 30 90° to the rotor axis whereby the vanes 8, when
they swing out, are not parallel to but are inclined
hand half of a vertical cross-section through a
to the rotor axis oppositely to the direction of
complete hydraulic turbine of the swivelling pro
the blades 6, as shown in Fig. 4, their surfaces
peller bladed type incorporating the invention;
thus having a more marked tendency to divert
Figure 2 is an enlargement of apart of the upper
the
incoming water on its way to the driving
end of the turbine shown in Figure 1; Figure 3 35 blades 6. It will be‘appreciated, however, that
is an enlargement of, the pivoted braking vane
the axes of the hinge pins could be either hori
shown in Figure 1; Figure 4 is a perspective
zontal or vertical and the surfaces of the vanes
view-showing the swivelling blades and a ring
either vertical or specially shaped to divert the
of braking vanes of part of the rotor of the tur
water.
40
bine shown in Figure 1, the vanes projecting in
Hinged vanes 8 are counter-balanced by por
the fully operative position; Figure 5 is a view
tions such as 80 in Fig. 3 to reduce the effect of
corresponding to Figure 3 of a slightly modi?ed
centrifugal force, thereby allowing of the use of
form ofv braking vane; and, Figures 6 and '7 are
weaker retaining means.
inclined views of a detail of Figure 2, but to a 45
The vanes are provided with means normally
retaining them flush with the ring 1 until a cer
larger scale than Figure 2.
tain centrifugal force and hence a certain speed
' In Fig. 1 the turbine is of conventional swivel
is exceeded. These retaining means may be
ling propeller bladed type. . The stator includes
springs; alternatively they may be breaking links
the enveloping turbine casing I from which the
incoming water flows through the spaces between 50 which are snapped by the action of centrifugal
force, or they may be a combination of springs
the pivoted shutters 2 on its way to the rotor
and breaking links as shown in Figs. 1 and 2.
blades. The shutters are operated in the usual
As shown in Figs. 1, 2 and 3 each vane 8 is con
manner by the lever and link mechanism indi
nected by a ?exible cable l9-e. g. a steel wire
cated at 3 under the automatic (control of the
turbine speed governor. The rotor comprises the 55 rope—passing over an adjacent pulley ill on the
f“
3
2,407,454‘
rotor and vertically along a groove formed be
tween the vertical shaft 4 and the usual protec
tive sleeve l2 thereon (see Fig. 1) to the retain
ing means at the upper end of the shaft shown
in the enlarged view Fig. 2. The upper end of
the cable NJ is coiled around and anchored to
the drum l3 mounted on one of a number of
bearings 2! carried by the rotor. Turning with
the drum I3 is another drum l4 while coiled
4
device, thus releasing the link rod 16. At this
speed the centrifugal force acting on the vane 8
causes a pull on the upper cable is which while
insufiicient to snap the reduced portion Ilia of
the breaking link 16 is more than su?ioient to
overcome the upward force of the spring 19. Ac
cordingly on the release of the latch device, all
the vanes ?y out substantially simultaneously
under the action of centrifugal force aided by the
around and anchored to the latter is another 10 action of the water once the vanes have started
cable l5 directly attached to a link rod [6, the
to move. In the unlikely event of any latches 20
upper end l6a of which is of such reduced cross
not releasing, the individual breaking links l6
section as to snap when the desired pull is applied
will snap under the action of the centrifugal
to the link which thus serves as a breaking link
force at a slightly higher speed and so allow each
for releasing the associated vane 8 under the ac-. 15 vane to ?y out. When the turbine rotor has sub
tion of a predetermined centrifugal force. In the
sequently been brought substantially to a stand
arrangement shown the drum I4 is of smaller
still, the springs H can pull up the cables l5
diameter than the drum l3 so that the combina
and Ill to their normal position. and. withdraw the
tion forms a reducing arrangement whereby the
vanes into the ring 1.
movement of the broken link rod l6-—when the 20
Operation of the speed limiting device can be
associated vane flies outs-is less than the move
seen since the latch 28
visible and downward
ment of the cable Ill, but it will be understood
movement of the link rods !5 can be observed.
that these drums could, if desired, be both of the
‘To facilitate this observation, markings Ila may
same diameter or that the cable 10 could be di
be provided on the shaft adjacent to the ?ange oi"
rectly connected to the link rod IS.
the collar 58 which moves down with the link 16.
The link rod l6 slides through a guide sleeve 57
Failure of any one of the retaining devices-wom
carried by the rotor and carries towards its upper
prising the combination or" breaking link l6 and
end a collar [8. Surrounding the sleeve 51 and
spring i9—~to retain or withdraw its associated
the collar it‘ between the flanges thereon is the
' coiled compression spring I9 which is a compara
tively light spring exerting on the cable l0 only
suf?cient force to retain the associated Vane at
a comparatively low speed of the rotor.
The described retaining devices-one for each
of the vanes 8—are arranged in a ring around
the shaft and all are normally held up by the
engagement of the upper end of each link rod
IS with a latch‘Zil' which can be released in
known manner by the ordinarily provided over
speed trip device. The well-known form of op
erating member for ‘this device—comprising the
tappet pin 22 which, under the action of cen
trifugal force, can slide (against the action of
the spring 23) radially outwards in the sleeve
portion 24a forming part of the annular struc
ture 24 secured to and carried around by the
shaft 4--can be seen in Figs. 2 and 6. The tappet
22, when it moves out, engages and moves the
operating lever 21 of the Well-known comple
mentary part of the trip device attached to a
?xed portion of the turbine casing, which part
sets in motion valve means to cut off the supply
of water to the rotor blades of the turbine, as
already mentioned. The upper end of the said
operating lever 21 which can be seen at 26 in
Figures 2, 6 and 7 is then in a position to engage
the end of each latch 29 as they are moved in suc
cession past the lever 27 by the rotation of the
shaft. Each latch 20 is shown as being movable
clear of the underside of the head of link rod
part ltd by turning about the vertical pivot pin
25 secured on and carried around with the said
annular structure 24, and will be so moved by
the engagement with the ‘end 26 of lever 21.
Figure 6 shows the tappet 22 in its normal posi-
tion when it is just passing the lever 21, while
Figure '7 shows one of the latches 20 just passing
the upper part 26 of the lever 21; the chain lines
in Figure 7 show the position of part 26 when
the tappet 22, in response to excessive overspeed,
has engaged lever 21, in which position part 26
can engage and move latch 29 as the turbine
vane 8 can also be seen.
In the unlikely event
of breakage of any one of the cables [0 or E5, the
associated spring is will force the free upper
end of the link rod it above its normal position
and this again can be seen. The retaining means,
being outside the water, are readily available for
adjustment 'or replacement of the springs l9 and
for replacement of the breaking links it after
snapping.
A modi?cation is shown in Fig. 5 which is a
section through one vane and an end View of an
other vane of a ring of retarding vanes 8 each
slidably mounted within the ring 7 but with its
vsurface shaped for diverting the incoming water,
as can be seen from the said end View. The slid
ing vane 8 (shown in its outer position by the
- chain lines) takes the place of the pivoted vane
B of Fig. 3 and is connected by the ?exible cable
Ii] to retaining means exactly as already de
scribed with reference to Figs. 2 and 3; it will be
clear that this sliding vane will tend to move out
into the stream under the action of centrifugal
force just as ‘does the hinged vane previously de
scribed.
What I claim as my invention and desire to
‘secure by Letters Patent is‘:
1. In combination, a hydraulic turbine rotor,
driving blades mounted on the rotor, a ring of
‘speed-limiting vanes mounted on the rotor and
free to move outwardly ‘under the action of cen
trifugal force into the water stream to limit the
.5, speed of the rotor, a ?exible cord attached to
each of said vanes and extending along the rotor
to an exposed position above the water stream,
guide pulleys for said cords and means holding
the ends of said cords at the said position above
.
the water stream to retain said speed-limiting
vanes out of the water stream until centrifugal
vforce corresponding to a predetermined safe
rotor overspeed is exceeded.
2. In combination, a hydraulic turbine rotor,
driving blades mounted on the rotor, a ring of
speed-limiting vanes mounted on the rotor and
movable under the action of centrifugal force
rotor rotates. '
into the Water stream to limit the speed of the
On a predetermined speed being exceeded, the
rotor, operative connections between said vanes
latch device 20 is released by thev overspeed trip 75 and an exposed position above the water stream,
2,407,454
6
force on the vanes (transmitted through the op
erative connections) at a predetermined exces
3. In combination, a hydraulic turbine rotor,
driving blades mounted on the rotor, speed-lim
iting vanes mounted on the rotor and movable
under the action of centrifugal force into the
water stream to limit the speed of the rotor and
sive rotor speed, springs exerting on said oper
ative connections a vane-retaining force but so
proportioned as to be overcome by centrifugal
stream, said retaining means having a weakened
part proportioned to break when the force there
force at a comparatively low rotor speed, a latch
on due to a predetermined safe overspeed of the
links at that position holding the ends of said
operative connections, said links being propor
tioned to snap under the action of centrifugal
means retaining said vanes out of the Water
device retaining each of said links (together with 10 turbine is exceeded.
the said springs) and latch-releasing means re
sponsive to an excessive rotor speed below that
speed at which the links are proportioned to
break.
PAUL WERNER SEEWER.
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