U.S. patent application number 12/604886 was filed with the patent office on 2010-04-29 for device for controlling the pitch of fan blades of a turboprop.
This patent application is currently assigned to SNECMA. Invention is credited to Wouter Balk, Gilles Alain Charier, Francois Gallet.
Application Number | 20100104438 12/604886 |
Document ID | / |
Family ID | 40688390 |
Filed Date | 2010-04-29 |
United States Patent
Application |
20100104438 |
Kind Code |
A1 |
Charier; Gilles Alain ; et
al. |
April 29, 2010 |
DEVICE FOR CONTROLLING THE PITCH OF FAN BLADES OF A TURBOPROP
Abstract
The invention relates to a device for controlling the pitch of
fan blades of a turboprop. The device includes at least at least
one set of adjustable pitch fan blades secured to rotate with a
rotary ring centered on a longitudinal axis and mechanically
connected to a turbine rotor. Each blade of the set is coupled for
pitch-adjustment purposes with a synchronization ring centered on
the longitudinal axis, the synchronization ring being suitable for
pivoting about the longitudinal axis relative to the rotary ring
under drive from actuators carried by the rotary ring and each
having a respective axis extending in a direction that is
substantially tangential to the synchronization ring.
Inventors: |
Charier; Gilles Alain; (La
Grande Paroisse, FR) ; Gallet; Francois; (Paris,
FR) ; Balk; Wouter; (Melun, FR) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND MAIER & NEUSTADT, L.L.P.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
SNECMA
Paris
FR
|
Family ID: |
40688390 |
Appl. No.: |
12/604886 |
Filed: |
October 23, 2009 |
Current U.S.
Class: |
416/128 ;
416/155 |
Current CPC
Class: |
F05D 2260/74 20130101;
F05D 2260/79 20130101; Y02T 50/60 20130101; F05D 2220/325 20130101;
Y02T 50/671 20130101; F02K 3/025 20130101; F01D 7/00 20130101; F05D
2260/56 20130101 |
Class at
Publication: |
416/128 ;
416/155 |
International
Class: |
F01D 1/24 20060101
F01D001/24; F01D 7/00 20060101 F01D007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 23, 2008 |
FR |
08 57205 |
Claims
1. A device for controlling the pitch of fan blades of a turboprop
having at least one set of adjustable pitch fan blades, said set
being constrained to rotate with a rotary ring centered on a
longitudinal axis and being mechanically connected to a turbine
rotor, wherein each blade of the set is coupled, for
pitch-adjustment purposes, to a synchronization ring centered on
the longitudinal axis, said synchronization ring being suitable for
pivoting about the longitudinal axis relative to the rotary ring
under drive from actuators, each comprising a cylindrical tube
fastened to the rotary ring and having a rigid rod suitable for
sliding therein, the rod extending in a direction that is
substantially tangential to the synchronization ring and having its
free end fastened to the synchronization ring.
2. A device according to claim 1, further including means for
providing longitudinal and radial guidance to the synchronization
ring relative to the rotary ring.
3. A device according claim 2, having a plurality of wheel means
carried by the rotary ring and co-operating with running tracks
formed on the synchronization ring so as to provide it with
longitudinal and radial guidance relative to the rotary ring.
4. A device according claim 3, wherein the outside surface of the
synchronization ring has two parallel running tracks extending in a
circumferential direction and separated by a projecting rib, the
wheel means each comprising two wheels rotatable about respective
axes parallel to the longitudinal axis and each co-operating with a
running track.
5. A device according claim 1, wherein each blade is mounted on the
rotary ring by means of a support suitable for pivoting about a
radial axis and connected to the synchronization ring via a drive
controlling rod.
6. A device according claim 1, wherein each actuator is fastened to
the rotary ring by means of lugs having respective axes that
coincide and that are parallel to the longitudinal axis.
7. A device according claim 1, wherein the rotary ring presents a
polygonal shape and is provided with openings in which the
actuators are mounted.
8. A device according claim 1, wherein the set has ten fan blades,
the synchronization ring being suitable for pivoting under drive
from five actuators.
9. A two-propeller turboprop comprising a turbine having two
contrarotating rotors and two sets of adjustable-pitch fan blades
constrained to rotate with two rotary rings connected to respective
ones of the rotors, the pitch of the fan blades of at least one of
the sets being controlled by a device according to claim 1.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to the general field of
turboprops having at least one set of fan blades that are
adjustable in pitch. The invention relates more particularly to
controlling the pitch of fan blades of an airplane turboprop having
two propellers.
[0002] In known manner, an airplane turboprop having two propellers
comprises a turbine with two contrarotating rotors each driving a
non-ducted set of fan blades. For example, reference can be made to
document GB 2 129 502 which describes various embodiments of such a
turboprop.
[0003] In that type of turboprop, the pitch of the fan blades in
each set constitutes one of the parameters that enables the thrust
of the turboprop to be controlled (this can also be referred to as
adjusting the orientation of the blades). Various devices already
exist for adjusting the pitch of fan blades in a given set. For
example, one known system consists in using an actuator that is
arranged axially in the inside space formed at the center of the
turbine. Mechanical connections transmit the movement of the
actuator rod radially to the adjustable pitch blades.
[0004] That type of control device requires mechanical connections
that are complex to provide, bulky, heavy, and expensive. In
addition, since the forces that need to be transmitted are large,
it is necessary to use an actuator that is operated at high
pressure. Unfortunately, an actuation pressure that is too high is
particularly harmful to the lifetime of the actuator. In addition,
the mechanical connections of that type of control device are not
easily accessible from inside the casing, and that complicates
maintenance operations.
[0005] Another control device is known from document EP 1 921 325.
It consists in using an annular actuator coupled to the set of fan
blades in order to adjust their pitch. Although satisfactory, such
a mechanism is not particularly well suited to actuating the fan
blades of the set that is located further downstream relative to
the turboprop. The space available for said downstream set is
small, which makes it necessary to have recourse to a device for
controlling the pitch of the fan blades that is of small size
radially.
OBJECT AND SUMMARY OF THE INVENTION
[0006] The present invention thus has a main object of mitigating
such drawbacks by proposing a device for controlling the pitch of
fan blades, which device is radially compact, light in weight, and
simple in design.
[0007] This object is achieved by a device for controlling the
pitch of fan blades of a turboprop having at least one set of
adjustable pitch fan blades, said set being constrained to rotate
with a rotary ring centered on a longitudinal axis and being
mechanically connected to a turbine rotor, wherein each blade of
the set is coupled, for pitch-adjustment purposes, to a
synchronization ring centered on the longitudinal axis, said
synchronization ring being suitable for pivoting about the
longitudinal axis relative to the rotary ring under drive from
actuators that are carried by the rotary ring and that have
respective axes extending in a direction that is substantially
tangential to the synchronization ring.
[0008] The control device of the invention presents the advantage
of constituting an independent module that is easily mounted on the
turboprop turbine in an already assembled configuration. It also
presents small size in a radial direction and can therefore easily
be located under the set of blades that is situated further
downstream relative to the turboprop. The weight of the control
device is also small. Finally, the device is placed outside the
turbine and is therefore easily accessible for maintenance
operations without it being necessary to begin by dismantling the
turbine.
[0009] In an advantageous disposition, the control device further
comprises means for providing longitudinal and radial guidance to
the synchronization ring relative to the rotary ring. Under such
circumstances, the control device may comprise a plurality of wheel
means carried by the rotary ring and co-operating with running
tracks formed on the synchronization ring. More precisely, the
outside surface of the synchronization ring may have two parallel
running tracks extending in a circumferential direction and
separated by a projecting rib, the wheel means each comprising two
wheels rotatable about respective axes parallel to the longitudinal
axis and each co-operating with a running track.
[0010] In another advantageous disposition, each actuator comprises
a cylindrical tube fastened to the rotary ring and having a rigid
rod slidably mounted therein and extending in a direction that is
substantially tangential to the synchronization ring and having its
free end fastened to the synchronization ring.
[0011] In yet another advantageous disposition, each blade is
mounted on the rotary ring by means of a support suitable for
pivoting about a radial axis and connected to the synchronization
ring via a drive controlling rod.
[0012] Each actuator of the control device may be fastened to the
rotary ring by means of lugs having respective axes that coincide
and that are parallel to the longitudinal axis.
[0013] The rotary ring may present a polygonal shape and is
provided with openings in which the actuators are mounted.
[0014] The set of the control device may comprise ten fan blades,
the synchronization ring being suitable for pivoting under drive
from five actuators.
[0015] The invention also provides a two-propeller turboprop
comprising a turbine having two contrarotating rotors and two sets
of adjustable-pitch fan blades constrained to rotate with two
rotary rings connected to respective ones of the rotors, the pitch
of the fan blades of at least one of the sets being controlled by a
device as defined above.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Other characteristics and advantages of the present
invention appear from the following description given with
reference to the accompanying drawings that show an embodiment
having no limiting character. In the figures:
[0017] FIG. 1 is a diagrammatic longitudinal section view of a
two-propeller turboprop;
[0018] FIG. 2 is a face view of a control device in accordance with
invention for controlling the pitch of fan blades;
[0019] FIG. 3 is an enlargement of a portion of FIG. 2;
[0020] FIG. 4 is a fragmentary view of the FIG. 2 control device
seen from an angle that is different from that of FIGS. 2 and 3;
and
[0021] FIG. 5 shows the longitudinal and radial guidance of the
synchronization ring for the FIG. 2 control device.
DETAILED DESCRIPTION OF AN EMBODIMENT
[0022] FIG. 1 is a highly diagrammatic view showing an embodiment
of an airplane turboprop of the type having two propellers.
[0023] Such a turbojet is itself known and is therefore not
described in detail. The turboprop 10 comprises in particular a
longitudinal axis 12 and an annular nacelle 14 disposed coaxially
around the longitudinal axis. The turboprop 10 also comprises, from
upstream to downstream: a compressor 16; a combustion chamber 18;
and a turbine 20 having two contrarotating rotors 22a and 22b,
these various elements all being disposed coaxially about the
longitudinal axis 12 of the turboprop.
[0024] The turboprop 10 also comprises an upstream set 24a and a
downstream set 24b of fan blades 26 of adjustable pitch. The fan
blades 26 in each set 24a, 24b are, more precisely, mounted on a
respective rotary ring 28a, 28b in the form of an annular platform
centered on the longitudinal axis 12 of the turboprop. The fan
blades in each set are regularly spaced apart circumferentially and
they extend radially from the surface of the respective rotary ring
28a, 28b. Each rotor 22a, 22b of the turbine 20 carries and drives
in rotation one of the rotary rings 28a, 28b having one of the sets
24a, 24b of adjustable pitch fan blades mounted thereon.
[0025] In order to adjust the thrust of the turboprop, it is known
to use a control device to modify the pitch of the blades (it is
also possible to speak of adjusting the orientation of the
blades).
[0026] The invention relates mainly to such a control device for
controlling the pitch of the blades in the set(s).
[0027] The control device described below with reference to FIGS. 2
to 5 applies more particularly to controlling the pitch of the fan
blades 26 of the downstream set 24b of the turboprop shown in FIG.
1. Naturally, this control device could also be applied to the
upstream set 24a of the same turboprop.
[0028] With reference to FIGS. 2 and 3, the control device of the
invention comprises a synchronization ring 30 that is centered on
the longitudinal axis 12 of the turboprop and that is disposed
coaxially inside the rotary ring 28b, which presents, in known
manner, a polygonal shape.
[0029] The synchronization ring 30 may pivot relative to the rotary
ring 28b about the longitudinal axis 12 of the turboprop. This
rotary movement in one direction or the other is controlled by
actuating actuators 32 that are carried by the rotary ring and that
have respective axes extending in a direction that is substantially
tangential to the synchronization ring.
[0030] More precisely, the actuators 32 (which may be hydraulic or
electrical) are regularly distributed circumferentially. Each of
them comprises a cylindrical tube 34 constituting the cylinder of
the actuator, the tube being fastened to the rotary ring 28b. A
rigid rod 36 extends in a direction that is substantially
tangential to the synchronization ring and is suitable for sliding
inside the cylinder 34 of the actuator. The free end of the rod is
mounted on the synchronization ring so as to pivot about an axis 37
that is substantially parallel to the longitudinal axis 12 of the
turboprop. As a result, when the rod slides inside the actuator
cylinder, it causes the synchronization ring to pivot relative to
the rotary ring 28 about the longitudinal axis 12.
[0031] As shown in FIG. 3, the cylinder 34 of each actuator 32 is
fastened to the rotary ring 28b by means of lugs 38 presenting axes
that coincide and that are parallel to the longitudinal axis 12 of
the turboprop. These lugs 38 are disposed in register with openings
40 (FIG. 4) formed in each side of the polygon forming the rotary
ring 28b so as to reduce its weight. Preferably, the lugs of the
actuators are located towards the middles of the actuator cylinders
so as to take up centripetal forces better.
[0032] Furthermore, each blade 26 of the set 24b is pivotally
mounted on the rotary ring 28b by means of a support 42 suitable
for pivoting about a radial axis 43. More particularly, the root of
each blade is mounted on the support 42 by means for example of a
dovetail-shaped fastener. The support 42 is pivotally mounted about
a radial axis 43 on the rotary ring between two adjacent openings
40, e.g. by means of a ball bearing (not shown).
[0033] Finally, each pivotal support 42 of a blade is connected to
the synchronization ring 30 via a driver connecting rod 44 hinged
at both ends (FIG. 4). As a result, pivoting the synchronization
ring about the longitudinal axis 12 of the turboprop causes the
support 42 to turn about the corresponding radial axis 43, thereby
changing the pitch of the blade mounted on said support.
[0034] The operation of the control device of the invention stems
clearly from the above description. The actuators 32 are actuated
simultaneously, e.g. under the control of the turboprop's
electronic control system (not shown in the figures). Under the
effect of this control, the rods 36 of the actuators slide inside
the cylinders of the actuator so as to cause the synchronization
ring 30 to pivot relative to the rotary ring 28b about the
longitudinal axis 12 of the turboprop. Since the synchronization
ring is connected to the blade support 42 by the driver connecting
rods, pivoting the ring causes said support to pivot about the
radial axes, thereby causing the pitch of all of the blades 26 to
be changed simultaneously.
[0035] According to an advantageous characteristic of the
invention, the control device also includes means for providing
longitudinal and radial guidance of the synchronization ring 30
relative to the rotary ring 28b.
[0036] As shown in particular in FIG. 5, these guide means may be
constituted by wheel pairs 46 carried by the rotary ring 28b and
co-operating with running tracks 48 formed on the synchronization
ring 30.
[0037] More precisely, the outside surface of the synchronization
ring 30 has two running tracks 48 that are parallel and that extend
in a circumferential direction. These running tracks are also
separated by a projecting rib 50. Furthermore, the wheel pairs 46
of the rotary ring comprise individual wheels 52 on common axes of
rotation 54 that are parallel to the longitudinal axis of the
turboprop, each individual wheel co-operating with a respective one
of the running tracks.
[0038] By running along the tracks 48, the individual wheels 52
making up each wheel pair 46 thus serve to provide the
synchronization ring 30 with radial guidance relative to the rotary
ring 28b. The longitudinal guidance of the ring is provided by the
presence of the rib 50 that is positioned between the two wheels
making up each pair.
[0039] Finally, FIG. 2 shows an example of a turboprop
configuration in which the set of blades on which the control
device of the invention is located has ten fan blades 26. In such a
configuration, five actuators 32 that are regularly distributed
around the plurality axis 12 of the turboprop can serve to cause
the synchronization ring 30 to pivot (the ring then being in the
form of a decagon). Furthermore, these actuators 32 can be
positioned between two adjacent fan blades 26 and they can
alternate with five wheel pairs 46 for providing the
synchronization ring with longitudinal and radial guidance (these
wheel pairs being likewise regularly distributed
circumferentially). Naturally, other configurations could be
envisaged depending on the number of fan blades to be controlled in
pitch.
[0040] Furthermore, the invention is described above in association
with a turboprop having a contrarotating turbine connected directly
to the propellers. Naturally, the invention also applies to
two-propeller turboprops in which the propellers are driven by
planetary gearing.
* * * * *