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Патент USA US2118654

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Patented May 24, 1938
con'mor. navrcn
‘Nlcol'aa's n. Groeneveld Heller, Schenectady
N. Y., assignor to General Electric Company.
a corporation of New York
' Application
I This invention relates to
June is, 1935, Serial’ No. 21,41:
Germany December
8, 1934
2 Claims. (0!. 110-1168)
control devices, more spond to the requirements of a pitch adjusting
particularly to devices for producing a controlling
action on a rotating body. and it has for an object
- the provision of a simple‘, reliable and improved
5 device of this character. '_
For example in certain types of machinery it
may be desired-to change the setting of a valve
mounted ‘on a rotating part of the machine.
, Likewise in certain types of governors, it may be
1-10 desired to change the setting of a control device
mounted on’ a rotating machine part‘; or in case
of apropeller for aircraft and the like, it is often
desired to control or vary the pitch of the blade
inclination for thepurpose of obtaining the maxi
15 mum‘output from the engine.‘
device for propeller blades.
A further advantage is the ‘comparatively small ~
weight so that only small centrifugal forces are
developed which do not seriously interfere with
reliable operation. In additio .. such an adjust
ing device requires only a small amount of super
vision during the operation. ‘It does not require
a complicated control system, as’ the electricv
power‘can be transmitted in‘ a simple manner l0.
over sliding or rotating contacts to the adjusting
elements which usually are located within the
propeller hub. If the adjusting element is heated
by exhaust gases or steam, these can be easily
‘conducted to the hub.
For a better and more complete understanding
Heretofore, various mechanical or hydrauli
devices have been utilized for this purpose, and
although some of these devices have been satis
of the invention, reference‘ should now be had
to the following specification and to the accom
propeller the high rotational speeds involved, in
troduce complications. The very considerable
Fig. 3 is a detail of a modification; Fig-(is a sec- [
factory, all'have left something to be desired. panying drawings in which Fig. 1 is a view of an
20 In the example of the variable pitch aircraft ‘ embodiment of ‘the invention partly in vsection; 20
centrifugal forces‘ as well asthe vibrations set
up in the propeller as a result of the impact of
explosions in ‘the _motor cylinders, shorten the
. 2
life and interfere _with the proper operation of
any complicated mechanism in _the propeller hub.‘
On the otherthand the large forces required to
7 turn the blades have in many designs required a
Fig. 2 is a plan view partly in section of Fig. 1;
' V
tional view of a modi?cation: and Fig. 5 is a de
tail of the modi?cation of Fig. 4.
Referring now to the drawings a pair of pro
peller' blades II and‘ ii are mounted in the propeller hub I! for rotation about their longitudi- '
nal axes. The propeller- blades are rotatably
mounted in any suitable type of bearings,
for example as ball or roller bearings. As shown,
30 large number of parts, in order to multiply a
small force to the required magnitude. This has. the blades ll and Ii are mounted in _roller bear
. required careful designing and accurate con
ings ll, I4, I‘ and I‘, ll, I8 respectively. The
races for the‘bearings il'and I! are suitably
mounted in the ‘hub, whilst the races for the
35, forces within the mechanism. _All these factors bearings i4 and H are carried by the supporting
add to the complexity of the device itself and to ’ arms ll, II which are preferably, formed inte
grally with the hub. The bearings I3, I4 and = the manufacturing cost as well.
Accordingly, an object of this invention is the II, II serve as guide bearings for rotation of the
provision of a device of this character which is blades about their own axes and the bearings I!
and il_ take the centrifugal thrust of the blades
40 extremely simple in construction, has a minimum
of moving parts, develops a large force with II and II respectively.
Although the‘roots of the
es in and u
a small movement, is easily designed and inex
may take many different forms, they are shown
' pensive to manufacture.
Incarrylng the invention into eifect in one as provided with control discs II and I2 respec
thereof, a thermal adjusting element vis ‘ tively each provided with a number of pins or
mounted on a‘ rotating part, for example the hub _ studs 23.
A suitable ' number of U-shaped bimetallic
of an aircraft propeller and means are provided
for supplying heat to the adjusting element to thermostatic elements are provided for adjusting.
cause it to deform and develop a large force for the pitch of each blade. In the illustrated Heme
struction in order not to introduce further com
plications such as unbalance and , centrifugal
adjusting the vpitch of the blades. The adjusting
bodiment, three bimetallic elements 2!, II and 2'
element may be heated either by electric power ' are provided for the blade II, and a similar num
or‘ by live exhaust gases from the engine or steam ber of bimetallic elements ll, II and 20 are pro- '
from a turbine. The heated adjusting element
itself may be of any suitable type such for ex
vided for the blade ll. These elements are ar
ample as abimetallic element, a bellows dia
respect to the blade axis as shown. Any suit
able bimetallic element may be utilized." For ex
phragm filled with suitable gas or liquid, a metal
ranged concentrically and symmetrically ‘with’
rod, or a‘, liquid cylinder with an operating pis-l_‘ ample, an element in which the low coemcient
The application of heat to these elements material is'an alloy of 36%; nickel and 64% iron
‘ causes small displacements or deformationsand and the high coefficient material is brass, is en
tirely satisfactory. A'greater or'lessernumber.” ‘
relatively large forces which conditions corres
~ ton.
of elements may be used to suit any particular
One end of the bimetallic element 24 is rigidly
connected to a web or plate I. which is integral
with the hub or connected thereto by suitable
,_ fastening means.
The opposite end of the ele
ment 24 is provided with a hole in which one of
power is available or the amount available is
' If an arrangement is provided for supplying
a cooling air current to the thermal adjusting
element for producing pitch variations opposite
to those produced by heating, then'it is preferred
to supply the cooling air and the heating gases
the pins 23 engages. The remaining thermo etc a common connection and to provide a con
static elements [are similarly mounted in the hub
10 and connected to the blades as indicated in the trol element at the point where the two supply
lines join. ' Reversing operation of this control
element provides for selectively supplying either
The bimetallic elements are heated by an elec
tric heating element II which is connected by
means of conductors I! which pass through a
bore 33 in the motor shaft or propeller shaft 34
to the slip rings II. These rings 35 are con
nected to a source of electric power, illustrated
as a generator 30, by means of the brushes 31.
A switching device 38 and a variable resistance
I! are included in circuit.
When the pitch of the propeller blades is to
be adjusted, then the switch II is closed. The
heating current in the heating element 3| can
then be regulated by means of the variable re
sistance 39. Heating of these, bimetallic elements
causes their free ends to attempt to bend out
the heating gases or the cooling airv to the ther
mal adjusting element.
In this further modification of the invention,
the rotating adjustment element is surrounded 16
by a stationary housing, to which the supply
lines of the heating gases and of the cooling air
are connected. The stationary housing is sealed
with respect to the rotating adjusting element,
by suitable means such as a labyrinth seal, in 20
order to prevent the heating gases from escap
ing before the heating of the adjusting element
is completed. If a bellows diaphragm is used as
the adjusting element, then a particularly simple ‘
construction is obtained by arranging the bel 26
lows diaphragm units so as to surround the mo
tor shaft, in which case suitable insulation can
wardly. If this bending is resisted these elements
develop large forces, which cause rotation of the be provided between the diaphragm and the mo
control discs II and 22 and consequently of the tor shaft in order to prevent the heat from being
blade shafts in the directions of the arrows shown ' transmitted to the motor shaft.
in the drawings.
As shown in Fig. 4 and Fig. 5, the propeller
The adjusting motion terminates ‘as soon as ' hub 46 is fastened to the motor shaft II by means
equilibrium is established between the supplied of the ?ange 48. Within this hub 4‘ the two
heat and the cooling by radiation and conduction. blade shafts 49 and ill are mounted in bearing
In order 'to reducewthe heat losses as much as bushings 5i and 52, respectively, for rotation 35
possible, the inside of the propeller hub I 2 can about their longitudinal axes. The root ends of
be covered with, a‘ thermal insulating layer 40. the blade shafts I! and BI are provided with
As the temperature of the bimetallic elements discs 53 and 54 respectively.‘ By means of these
is a measure. of the inclination of the propeller discs, the blade shafts 48 and 50 are held in place
blades, an indicating device ll is provided. This against the inside surfaces of the bearing bush
‘device may be an ammeter. If the voltage of ings i3 and 54 through the intermediary of roller
the source 30 is substantially constant, the mag
bearings 55 and II respectively.
nitude of the current in the circuit as measured
The discs 63 and ll of the blade shafts are pro
by the ammeter depends upon the resistance of vided with adjusting bolts or studs II, II respec
the circuit which in turn depends upon the tem
tively which are placed‘eccentrically with respect
perature ofvthe heating circuit. Likewise, the to the‘ center of the blade shafts. These two ad
temperature of the bimetallic element and the, ' justing bolts 51, II are held in sliding elements
degree of blade inclination depend upon the tem
58 and ill, respectively, which in turn cooperate
‘ture of the heating circuit. Consequently, with slots 6i and '2, respectively, of the' adjust
the ammeter may be calibrated in terms of blade ment yoke 83 so that they can be moved in a
inclination or pitch.
circular path when the yoke is moved axially in
In the construction shown in Fig. 3,
a‘l- , the hub. When the adjustment yoke is displaced
' ready stated. the electrically heated adjusting axially with respect to the hub, it is clear that
element is designed as a bellows diaphragm 42. if one blade is'rotated in one direction, the other
This diaphragm is’ fllled,with liquid, preferably blade
is rotated in the opposite direction. The 56
with a liquid which has a high thermal coeill
left end of this yoke 03 is provided with a hole to
cient of expansion. Within the diaphragm there permit axial displacement along the guide bolt
is provided a small tubular member 43 in which 64. This guide bolt is preferably screw threaded
a heating elements“ is located. The right hand
end of the bellows diaphragm is supported against into the propeller hub and has on its right end
an extension of the propeller hub, while the a head 65 ,which limits the displacementof the
adjustment yoke to the right.
left end acts on the control bolt of the control
disc ‘I constituting the root end of the pro ‘ The forked end of the adjustment yoke is fas
peller blade. If the heating wire II is heated \tened to a ?ange I! which is slidably mounted on
by closing the electric circuit, then the liquid
the bushing 61, which is, in turn, ilxedly secured
to the motor shaft 41. On the motor shaft 41, a
large force which in turn produces an adjust- - second ?ange II is provided, which together ‘with '
ment of the control disc 45 and consequently of the ?ange 6.! encloses the thermal adjusting ele
the blade shafts in the direction of 'the arrow ment illustrated as a bellows diaphragm ‘I,
located in the diaphragm expands, produces a
shown in the drawings.
In the modi?cation of Figs. 4‘ and 5, the ad
justing element is heated by the inlet gases or
exhaust gases of the propeller drive motor. This
makes it possible to utilize the thermal adjust
ing element in those cases in which no electric
mounted on the ?anges Cl and ‘I so as to
rotate with the motor shaft. This diaphragm
is mounted concentrically with respect to the
bushing 61, and consequently concentrically with
respect to the motor shaft 41, while suitable insu
lation ‘l8 placed in a turned part of the bushing 75
‘I, prevents the transmission of heat from the
diaphragm to the vmotor shaft.
The diaphragm 89 is ?lled with a liquid which
causes an axial change in the length of the dia
phragm when it is heated, thereby producing an‘
axial displacement of the adjusting‘ yoke 63 to
the left. This displacement of the adjustment
yoke 63 causes a rotation of the blade shafts in
such a way that one blade is rotated to the left,
‘ while the other is rotated to the right.
The bellows diaphragm 69, which rotates with
the motor shaft 41 since it is fastened to the
?anges 68 and 68 is enclosed in a stationary hous
ing, 'I'l to the upper part of which the two supply
lines 12 and‘ 13 for the heating gases and the
cooling air respectively are connected, and
whose lower part is designed as the outlet 14 for
the heating gases and the cooling air. The sta
tionary housing 'H is provided with a labyrinth
seal on the inside walls thereof which lie oppo
site to the ?anges 68 and 68 in order to prevent
escape of the heating gases, to the greatest pos
sible extent.
of pitch variation. _The arrangement illustrated
provides a pitch variation range of approximately
22 degrees, but by proper selection of the bellows '
length, permissible bellows temperatures and
suitable arrangement of yoke and pins the pitch
can be varied as‘ much as 90 degrees if desired.
The forces exerted by the expanding bellows.
are a multiple of the forces necessary to over
come the resultant of aerodynamic and centrifu
gal torques and the frictional torques in thrust-v
and lateral-blade bearings. The available pitch
changing forces being so large, there ‘should
hardly be any need for lateral ball- or roller
bearings, which will permit the use of simple
sleeve bearings or bushings, which affords an in
expensive and reliable construction.
15 “I
» .
Although in accordance with the provisions of
the patent statutes this invention is illustrated
as embodied in concrete form, it will be under
stood that, the apparatus shown and described is 20
merely illustrative, and that the invention is not
limited thereto, since alterations and modifica
tions will readily- suggest themselves. to persons, '
At the connection point of the two supply lines
\ ‘l2 and ‘I3 with the housing ‘II, a control element
illustrated as a three way valve 16 is provided.
By changing the position of this element either
the cooling air line 13, as shown, or the heating
gas linecan be connected to the inside ‘of the hous- -
skilled in the art without departing from the true
spirit of this invention ‘or from the scope of the‘ 25
annexed claims.
What I claim as new and desire to secure by
Letters Patent of the United States is:
1. A controllable pitch propellercomprising in
The control element 16 can, if necessary, combination a hub having a substantially com .30,
be placed in intermediate positions in which it ' pletely enclosed housing ‘member, a plurality of
admits both cooling air and also heating gas or propeller blades having their roots rotatably
only a part of the heating gas or of the cooling mounted within said housing member to provide
air. In this manner, a simple regulating means for rotation of said blades about their longitu
is "provided for the thermal power to be supplied. dinal axes, said roots being separated to provide .
The normal position of the propeller occurs' a space, a plurality of thermal responsive elements
when by proper setting of valve 1'8 air ?ows over for each of said blades mounted in said space,
- ing 1 I.
the bellows to keep them cool. When the pilot
desires to change the pitch of‘ his propeller, he
turns valve 16 to a position in which it admits
hot exhaust gases into housing ‘II. These hot
the elements for each of said blades being spaced
at substantially equal circumferential intervals
about the longitudinal blade axis and each having
one extremity connected to said hub and the other
connected to its associated blade root, an electric
gases heat the bellows which consequently ex
pand in an ‘axial direction, thereby displacing heating coil for each of said thermal responsive
yoke 63 forward (to the left in the drawings). - elements, and a source of electric power externalv
As a ‘result the propeller blades are rotated as ' to said housingmember, ‘and electrical connec
previously described.
The amount of pitch changing, can be regulated
by regulating the quantity of exhaust gases
which flow through the heating chamber formed
by the housing. This is done by choosing a cor
responding setting of the valve 18.
Should it become necessary to return the- pro
peller blades to the original position, valve 18 is
turned~ in such a way as to admit fresh cool air‘
over the bellows. This will cause the bellows to
contract, and the blades will return ‘to their nor
mal position through the‘ action of forces which
tend to restore them to their original positions.
In addition to these forces, which may be the‘
i result of aerodynamic pressure, centrifugal action
tions from said source to said coils for supplying
electric energy to said coils thereby to cause said
thermal responsive elements to produce a force
to rotate said blades about said axes.
2. 'A controllable pitch propeller comprising a 60'
substantially completely enclosed hollow hub
member, a plurality of propeller blades having
their roots rotatably mounted within said hub
member to provide for rotation of said blades
about their longitudinal axes, each of said blade 55
roots having a'fianged portion forming a disc‘,
said'discsbei'ng separated to provide a space, a
plurality of supporting arms one for each blade
within said hub, antifriction guide bearings for
said blades carried by said arms, thrust bearings
arranged between said discs and supporting arms,
of counterweights or spring action, the spring
effect of the‘ bellows also tends‘ to return the a a plurality of U—shaped bimetallic themostatic
elements for each of said blades arranged within
‘blades to their original position. In order to pre
vent the blades from being turned back too far in said space, the elements for each blade being sub
cold weather. an adjustable stop consisting of the stantially equally spaced circumferentially about
bolt 84 which prevents yoke” from moving too the axis of the blade and each having one extrem
far to the right, is provided. This bolt 64 is held ity fastened to its associated disc and the other
tight by nut ‘H in the nose of the propeller. In to'said hub, an electric~heating coil on each of
“cold”~ position ?ange ll rests against head. 05 said elements, and electrical connections from
said coils to an external source of power for,
of bolt ll.
. .
For normal flying and temperature conditions supplying power to said coils to cause said ele
the position ‘of valve ‘II will be an indication of ments to produce a force to rotate said blades
thepropelle'r pitch. .
This construction provides .ior a large range
about said'axes.
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