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Патент USA US3056551

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Oct. 2, 1962
D. B. FOWERAKER
3,056,541
ADJUSTABLE PITCH GUIDE BLADES
Filed March 25. 1959
atkg‘“
2 Sheets-Sheet l
Oct. 2, 1962
D. B. FOWERAKER
3,056,541
ADJUSTABLE PITCH cum: BLADES
Filed March 23. 1959
2 Sheets-Sheet 2
Unitcd States Patent O?tice
3,056,541
Fatented Get. 2, 1962
2
.11
it
FIGURE 3 is a plan of a modi?ed link for connection
3,056,541
David Bruce Foweraker, Bristol, England, assignor, by
ADJUSTABLE PITCH GUIDE BLADES
rnesne assignments, to Bristol Siddeley Engines Limited,
Bristol, England, a British company
Filed Mar. 23, 1959, Ser. No. 801,364
Claims priority, application Great Britain Mar. 26, 1953
5 Claims. (rill. Z39-l1®
This invention relates to adjustable pitch guide blades 10
to actuator means,
FIGURE 4 a section of a rocker arm, the section being
taken on line 4—4 of FIGURE 3,
FIGURE 5 shows the full circular arrangement of the
guide blades, the number of blades being an odd number,
and
FIGURE 6 shows the full circular arrangement Where
the number of blades is even.
Referring to the drawings, the outer frusto-conical wall
in axial flow rotary compressors. The invention is con
cerned with a linkage for connecting a ring of such guide
It} of the annular intake passage of a multi-stage axial ?ow
rotary gas compressor is provided ‘with a ring of equally
blades for simultaneous pitch control.
spaced apertures. These apertures receive recessed plates
The invention is particularly applicable to multi-stage, '
axial ?ow rotary air compressors in gas turbine jet pro
pulsion engines for aircraft. Such machines have been
provided with adjustable pitch guide blades in order to
permit them to operate more e?iciently over a wider
which are secured to the outer wall 16‘ by bolts 15.
The plates 14- are centrally apertured to provide blade
mountings for the blades 11 of a ring of guide blades,
three of which are partially shown in FIGURE 1. The
outer portions of each guide blade terminate in a hollow
trunnion 25. This hollow trunnion 25 is surrounded by
range of rotational speeds. The adjustable guide blades
may conveniently ‘be mounted in bearings in the outer 2O a sleeve 12 which is ?anged at its innermost end. The
wall of the air intake passage feeding the compressor, and
the linkages for connecting the guide blades may con
veniently be located on the exterior of the outer wall
?anged sleeve 12 is of increased outer diameter at its
lower end near the ?ange to be received within the bushes
17. These bushes T7 are carried in the aperture of the
and therefore outside the air intake and out of contact
recessed plate 14 and are of the same axial length as the
with the intake air ?ow. In that case the blade-connect 25 part of the sleeve 12 of enlarged diameter. Surrounding
ing linkage will experience temperatures which may diller
the sleeve 12 at its smaller diameter part is the hub 13 of
appreciably from those experienced at the same time by
a rocker arm (13, 18a or 18b in FIGURES 2 and 3).
the outer wall of the air passage in which the guide blades
The hub 13 is ?anged at its lower end to bear on the
are mounted, and should circumferential expansion or con
step between the larger and smaller parts of the sleeve 12
traction of the outer wall occur so as to tend to create 30 and the bushes 17 are provided with ?anges at each end
relative movement between the wall and the linkage, a
which ?t into the recessed plate which is shaped to pre
cumulative interference with the selected pitch of the con
vent the bushes 17 moving towards one another. The
nected guide blades may result.
?ange at the lower end of the hub 13 bears also on the
According to this invention there is provided an axial
outer of the ?anges of the bushes 17, and the ?ange of
?ow rotary compressor comprising a boundary wall for
the sleeve 12 bears against the inner flange of the bushes
the working ?uid, a ring of radially-extending guide blades
17. The hub 13, sleeve 12 and trunnion are provided
each journaled in the boundary wall for rotation about a
with registering diametral holes through which a split
radially-extending axis to adjust the pitch thereof, the axes
tapered pin 16 is passed. The blades 11 are thus mounted
of rotation of the blades lying in a common radial plane,
for free rotation about the axis of the trunnion 25 but
and the blades having respective actuating arms connected 40 are held against axial movement by the mounting of the
thereto and arranged substantially parallel to each other,
?anges as described.
each arm extending axially on each side of said plane, and
Each rocker arm (18, 18a, 18b) normally extends
a series of circumterentially extending links offset from
transversely of the plane containing the pivot axes of
but extending parallel to said plane, which links connect
the blades in the ring. Each double-ended rocker arm
all the arms in train with each other, the arrangement be 45 (18, 18b) has its hub approximately at its centre. The
ing such that the arm of each blade is respectively con
nected to the arms of the two next adjacent blades by two
of said links, which two links are disposed on opposite
sides of the said plane, and means connected to one of
the blades for holding it in selected angular positions about
its axis.
In one form of the present invention the series of
parallel-motion linkages has free ends in the sense that
ends of the rocker arm are bifurcated and drilled to sup
port a link pin 20. The link pin 20 is engaged by an eye
bolt 21 which has a threaded shank 22. This shank 22
enters and engages the internally-threaded adjacent end
of a connecting sleeve 23 to constitute therewith and
with a shank 22 engaged with the other end of the con
necting sleeve 23 a link member which extends parallel to
the plane containing the pivot axes of the blades in the
ring. The rocker arms 18 and the link members are so
there is one pair of adjacent rocker arms which are not 55
arranged that any one double-ended rocker arm 18 is
connected together by a link member, and in this case
connected to the adjacent two rocker arms respectively by
an actuating means for adjusting the blade pitch is prefer
a link member at each end, which link members lie in
ably connected to one of the rocker arms at or near the
planes on opposite sides of the plane containing the axes
middle of the series.
Alternatively however, if there is an even number of
blades, the series may be endless in the sense that every
pair of adjacent rocker arms is connected together by a
link.
One embodiment of the invention will now be described
of the blades in the ring. The link members and rocker
arms thus constitute parallel motion linkages and together
form a linkwork actuated by a pitch actuator as will here
inafter be described. In this embodiment there are an
odd number of blades in the blade ring, two of the blades
not being connected together by a link member, so that
the system has two free ends. The rocker arms are all
double~ended (as shown at 18) except for the rocker arms
18a connected to the two end blades, i.e. the blades which
are not linked together. These rocker arms 18a are single
by way of example and with reference to the accompany
ing drawings which show details of a multi-stage, axial
?ow, rotary gas compressor.
FIGURE 1 being a section along line l.—1 of FIG
ended as will be seen in FIGURE 2 where one is shown.
URE 2,
70 The mid-blade of the blade ring i.e. the guide blade
FIGURE 2 a plan view of an arcuate portion of an
having an equal number of blades between it and the
outer wall of an annular gas passage of FIGURE 1,
end blades on either side of it, is provided with a modi
3,056,541
4
3
?ed rocker arm 13b.
blades by two of said links, which two links are disposed
on opposite sides of the said plane, and means connected
to one of the blades for holding it in selected angular posi
tions about its axis.
This rocker arm 18b is provided
with an additional arm 24 for connection to the pitch ac
tuator. The arm 24 is bifurcated at its end for engagement
by an eye bolt 21, the latter being screw threaded to a
connecting sleeve 23 which is connected to the ram of an
2. An axial ?ow rotary compressor as claimed in claim
1, wherein at least some of the links are adjustable in
actuator for controlling the blade pitch. The actuator may
be controlled in any desired manner, for instance it may
be made responsive to the compressor r.p.m.
length.
3. An axial ?ow rotary compressor comprising a bound
ary Wall for the working ?uid, a ring of radially-extend
ing guide blades each journaled in the boundary wall for
rotation about a radially-extending axis to adjust the pitch
In operation, the actuator ram is moved to rock the
modi?ed rocker arm 18b. The resultant rocking move
ment is simultaneously transmitted by the open ended
series of parallel motion linkages to the blades 11 on
thereof, the axes of rotation of the blades lying in a com
mon radial plane, and the blades having respective ac
tuating arms connected thereto and arranged substantially
parallel to each other, each arm extending axially on
each side of said plane, and a series of circumferentially
both sides of the modi?ed rocker arm so as to cause them
to pivot together about their respective pitch axes and
to change their angle of pitch by the desired amount.
If the outer wall of the intake passage contracts or ex
extending links offset from but extending parallel to said
pands, the spacing between any two adjacent blades will
plane, which links connect all the arms in train with each
vary and thus the spacing between the pivot axes of the
other, the arrangement being such that the arm of each
rocker arms supported by these blades will also vary. If,
however, the linkage is not similarly affected, as may well 20 blade is respectively connected to the arms of the two next
adjacent blades by two of said links, which two links are
be the case because, for example, the inner surface of
disposed on opposite sides of the said plane, and means
the outer wall 10 but not the linkage is scrubbed by the
connected to one of the blades for holding it in selected
intake ?ow of gas, the variation in spacing between three
angular positions about its axis, and wherein considering
adjacent blades will be accommodated by a slight rocking
movement of the rocker arm of the middle blade only, 25 the blades in groups of three neighboring blades, the
lengths of the two links connected to the arm which is
the orientation of the rocker arms of the blades on each
connected to the middle blade of the group are x and y
side of it remaining unaffected. Thus a cumulative inter
ference with the blade pitch is not permitted to build up.
respectively, the distances from the axis of rotation of
The rocker arms which will rock will be the arms spaced
by an odd number of spaces from rocker arm 18b, i.e. the
two arms adjacent rocker arm 18!) and each alternate
each blade to the points of connection to that blade of
the two associated links are u and v respectively, and the
values of u, v, x, and y satisfy the equation
rocker arm thereafter. When there is an even number of
blades in the ring every pair of adjacent rocker arms
may be connected together by a link.
4. An axial ?ow rotary compressor comprising a bound
Considering any group of three rockers, for example 35
ary wall for the working ?uid, a ring of radially-extending
the three rockers shown in FIGURE 2, if the spacings x
guide blades each journaled in the boundary wall for rota
and y between the rocker axes are equal, then the lengths
tion about a radially-extending axis to adjust the pitch
u and v of the arms of the middle rocker must be equal
thereof, the axes of rotation of the blades lying in a com
to ensure that, if the right hand side rocker is ?xed and
the distances at and y change equally, only the middle 40 mon radial plane, and two of said blades which are next
adjacent each other having lever arms connected thereto
rocker turns around its axis. If however the spacings x
which extend parallel to each other and transversely to
and y are unequal, and change respectively by ax and ay
said plane, and the two lever arms being free to any direct
(a being for example a coei?cient of linear thermal ex
linkage between them, and the other blades having respec
for the left hand rocker to remain non rotated a(x+y) 45 tive actuating arms connected thereto and arranged sub
stantially parallel to the said lever arms, each actuating
must be equal to
pansion multiplied by a temperature difference), then
a0;
(u-l-v)
——
u
from which it follows that
with
u
_
arm extending axially on each side of said plane, and a
series of circumferentially extending links offset from but
parallel to said plane which links connect all the arms,
including the said lever arms, in train with each other,
50 each of the actuating arms being respectively connected
to the arms of the two next adjacent blades by two of
said links, which two links are disposed on opposite sides
of the said plane, and means connected to one of the blades
:0
The screw-threaded connection between the sleeve 23
and the eye bolts 21 permits manual adjustment of in
dividual linkages.
55
I claim:
1. An axial ?ow rotary compressor comprising a bound
ary wall for the working ?uid, a ring of radially-extend
ing guide blades each journaled in the boundary wall for
rotation about a radially-extending axis to adjust the pitch 60
thereof, the axes of rotation of the blades lying in a com
mon radial plane, and the blades having respective ac
tuating anns connected thereto and arranged substantially
parallel to each other, each arm extending axially on each
side of said plane, and a series of circumferentially extend
ing links offset from but extending parallel to said plane,
which links connect all the arms in train with each other,
the arrangement being such that the arm of each blade is
respectively connected to the arms of the two next adjacent
for holding it in selected angular positions about its axis.
5. An axial ?ow rotary compressor as claimed in claim
3, comprising actuating means for adjusting the pitch of
the blades, which actuating means is connected to one of
the said arms on the opposite side of the ring of blades to
the blades having said lever arms.
References Cited in the ?le of this patent
UNITED STATES PATENTS
2,388,208
2,393,042
2,435,092
2,793,804
2,857,092
2,858,062
Foss ________________ __ Oct.
Hagen _______________ __ Jan.
Meyer _______________ __ Jan.
Woodbury ___________ __ May
Campbell ____________ __ Oct.
Allen ________________ __ Oct.
30,
15,
27,
28,
1945
1946
1948
1957
21, 1958
28, 1958
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