U.S. patent application number 13/089792 was filed with the patent office on 2012-10-25 for turbine driveshaft for ram air turbine.
This patent application is currently assigned to HAMILTON SUNDSTRAND CORPORATION. Invention is credited to Stephen Michael Bortoli, Dustin L. Kaap, Vladimir Korchagin, Paul Henry Verstrate.
Application Number | 20120269616 13/089792 |
Document ID | / |
Family ID | 47021474 |
Filed Date | 2012-10-25 |
United States Patent
Application |
20120269616 |
Kind Code |
A1 |
Bortoli; Stephen Michael ;
et al. |
October 25, 2012 |
TURBINE DRIVESHAFT FOR RAM AIR TURBINE
Abstract
A driveshaft for an aircraft ram air turbine includes a tubular
body and a flange. The tubular body defines an axis of rotation and
includes a forward portion and a frusto-conical portion located
rearward of the forward portion. The flange adjoins the forward
portion of the tubular body opposite the frusto-conical portion,
and has a forward face and an opposite rear face. A ratio of an
outer diameter of the forward portion of the tubular body to an
inner diameter of the forward portion of the tubular body is in a
range of approximately 1.423 to 1.425.
Inventors: |
Bortoli; Stephen Michael;
(Roscoe, IL) ; Kaap; Dustin L.; (Rockford, IL)
; Verstrate; Paul Henry; (Loves Park, IL) ;
Korchagin; Vladimir; (Loves Park, IL) |
Assignee: |
HAMILTON SUNDSTRAND
CORPORATION
Windsor Locks
CT
|
Family ID: |
47021474 |
Appl. No.: |
13/089792 |
Filed: |
April 19, 2011 |
Current U.S.
Class: |
415/122.1 ;
29/889.2 |
Current CPC
Class: |
Y10T 29/4932 20150115;
F16C 2326/06 20130101; F16C 3/02 20130101; F02C 7/32 20130101 |
Class at
Publication: |
415/122.1 ;
29/889.2 |
International
Class: |
F01D 15/12 20060101
F01D015/12; B21K 25/00 20060101 B21K025/00 |
Claims
1. A driveshaft for an aircraft ram air turbine, the driveshaft
comprising: a tubular body that defines an axis of rotation and
that includes a forward portion and a frusto-conical portion
located rearward of the forward portion; and a flange adjoining the
forward portion of the tubular body opposite the frusto-conical
portion, the flange having a forward face and an opposite rear
face, wherein a ratio of an outer diameter of the forward portion
of the tubular body to an inner diameter of the forward portion of
the tubular body is in a range of approximately 1.423 to 1.425.
2. The driveshaft of claim 1 and further comprising: a hub pilot
located adjacent to the forward face of the flange, wherein a ratio
of the outer diameter of the forward portion of the tubular body to
the hub pilot diameter is in the range of approximately 1.359 to
1.380.
3. The driveshaft of claim 1, wherein a length of the tubular body,
measured in an axial direction, is approximately 22.715 cm (8.943
inches).
4. The driveshaft of claim 1, wherein the frusto-conical portion is
arranged at approximately 14.degree. with respect to the axis.
5. The driveshaft of claim 1, wherein the forward face of the
flange is arranged at approximately 2.degree. with respect to the
axis, and wherein the rear face of the flange is arranged at
approximately 9.degree. with respect to the axis.
6. The driveshaft of claim 1 and further comprising: a hub pilot
located adjacent to the forward face of the flange, wherein the hub
pilot has a diameter of approximately 18.001 cm (7.090 inches),
wherein a length of the tubular body, measured in an axial
direction, is approximately 22.715 cm (8.943 inches), wherein the
frusto-conical portion is arranged at approximately 14.degree. with
respect to the axis, wherein the forward face of the flange is
arranged at approximately 2.degree. with respect to the axis, and
wherein the rear face of the flange is arranged at approximately
9.degree. with respect to the axis.
7. A driveshaft for an aircraft ram air turbine, the driveshaft
comprising: a tubular body that defines an axis of rotation and
that includes a forward portion and a frusto-conical portion
located rearward of the forward portion; and a flange adjoining the
forward portion of the tubular body opposite the frusto-conical
portion, the flange having a forward face and an opposite rear
face, wherein the frusto-conical portion is arranged at
approximately 14.degree. with respect to the axis, and wherein the
rear face of the flange is arranged at approximately 9.degree. with
respect to the axis.
8. The driveshaft of claim 7, wherein the forward face of the
flange is arranged at approximately 2.degree. with respect to the
axis.
9. The driveshaft of claim 7, wherein an outer diameter of the
forward portion of the tubular body is approximately 7.117 cm
(2.802 inches) and an inner diameter of the forward portion of the
tubular body is approximately 4.994 cm (1.966 inches).
10. The driveshaft of claim 7 and further comprising: a hub pilot
located adjacent to the forward face of the flange, wherein the hub
pilot has a diameter of approximately 18.001 cm (7.090 inches).
11. The driveshaft of claim 7, wherein a length of the tubular
body, measured in an axial direction, is approximately 22.715 cm
(8.943 inches).
12. The driveshaft of claim 7, wherein the frusto-conical portion
is arranged at approximately 14.degree. with respect to the
axis.
13. The driveshaft of claim 7 and further comprising: a hub pilot
located adjacent to the forward face of the flange, wherein the hub
pilot has a diameter of approximately 18.001 cm (7.090 inches),
wherein a length of the tubular body, measured in an axial
direction, is approximately 22.715 cm (8.943 inches), wherein the
frusto-conical portion is arranged at approximately 14.degree. with
respect to the axis, wherein the forward face of the flange is
arranged at approximately 2.degree. with respect to the axis,
wherein an outer diameter of the forward portion of the tubular
body is approximately 7.117 cm (2.802 inches), and wherein an inner
diameter of the forward portion of the tubular body is
approximately 4.994 cm (1.966 inches).
14. A ram air turbine assembly for an aircraft, the assembly
comprising: a turbine subassembly having a rotatable hub; a gearbox
positioned adjacent to the hub; a strut positioned adjacent to the
gearbox, wherein the strut supports the gearbox; a power conversion
device; and a drivetrain operably connected between the turbine
subassembly and the power conversion device, the drivetrain having
a turbine driveshaft attached to the hub and located at least
partially within the gearbox, the turbine driveshaft including: a
tubular body that defines an axis of rotation and that includes a
forward portion and a frusto-conical portion located rearward of
the forward portion; and a flange adjoining the forward portion of
the tubular body opposite the frusto-conical portion, the flange
having a forward face and an opposite rear face, wherein a ratio of
an outer diameter of the forward portion of the tubular body to an
inner diameter of the forward portion of the tubular body is in a
range of approximately 1.423 to 1.425.
15. A method of installing a driveshaft in an aircraft ram air
turbine, the method comprising: providing a driveshaft having a
tubular body that includes a forward portion and a frusto-conical
portion located rearward of the forward portion, and a flange
adjoining the forward portion of the tubular body opposite the
frusto-conical portion, the flange having a forward face and an
opposite rear face, wherein a ratio of an outer diameter of the
forward portion of the tubular body to an inner diameter of the
forward portion of the tubular body is in a range of approximately
1.423 to 1.425; positioning the driveshaft at least partially
within a gearbox; and operatively engaging the driveshaft in a
drivetrain that extends between a turbine and a power conversion
device.
Description
BACKGROUND
[0001] The present invention relates generally to driveshafts and
their manufacture, and more particularly to driveshafts for use in
housings and/or gearboxes of ram air turbines (RATs) and their
method of manufacture.
[0002] RATs are used on aircraft to provide an emergency power
supply to power a generator, hydraulic pump, etc. When not in use,
the RAT is generally stowed within the aircraft fuselage. When the
aircraft is in flight, the RAT can be deployed to generate power as
turbine blades of the RAT spin in oncoming airflow around the
aircraft. The RAT can be deployed as a secondary or emergency
system when power is unavailable from primary systems of the
aircraft.
[0003] Driveshafts used in RAT drivetrains are subject to many
requirements. The RAT driveshaft must be reliable and it must be
able to mate with necessary drivetrain components and be able
handle the torque loads to which it will be subjected. Due to the
fact that most RATs protrude outward from an aircraft's fuselage in
a cantilevered manner, RATs and their subcomponents are subject to
a significant amount of vibration and bending. Moreover, the
rotational nature of RAT drivetrains can introduce torsional
resonance issues. However, because positioning of the RAT in the
aircraft must account for numerous other aircraft design factors,
the location of the RAT and its subcomponents is highly
constrained, which greatly limits design options for the geometry
and dimensions of the RAT drivetrain and its driveshafts. Weight of
RAT components is also an important design consideration.
SUMMARY
[0004] A driveshaft for an aircraft ram air turbine according to
the present invention includes a tubular body and a flange. The
tubular body defines an axis of rotation and includes a forward
portion and a frusto-conical portion located rearward of the
forward portion. The flange adjoins the forward portion of the
tubular body opposite the frusto-conical portion, and has a forward
face and an opposite rear face. A ratio of an outer diameter of the
forward portion of the tubular body to an inner diameter of the
forward portion of the tubular body is in a range of approximately
1.423 to 1.425.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] FIG. 1 is a cross-sectional view of a ram air turbine (RAT)
according to the present invention.
[0006] FIG. 2 is an enlarged perspective view of a portion of the
RAT of FIG. 1.
[0007] FIG. 3 is a cross-sectional view of the portion of the RAT
of FIG. 2, taken along line 3-3 of FIG. 2.
[0008] While the above-identified drawing figures set forth
embodiments of the invention, other embodiments are also
contemplated, as noted in the discussion. In all cases, this
disclosure presents the invention by way of representation and not
limitation. It should be understood that numerous other
modifications and embodiments can be devised by those skilled in
the art, which fall within the scope and spirit of the principles
of the invention. The figures may not be drawn to scale Like
reference numbers have been used throughout the figures to denote
like parts.
DETAILED DESCRIPTION
[0009] FIG. 1 is a cross-sectional view of a ram air turbine (RAT)
10 for use with an aircraft (not shown). For simplicity, FIG. 1 is
shown without cross-hatching. The RAT 10 includes a turbine
assembly 12, a strut 14, a generator 16, and a drivetrain (or
driveline) 18 that includes a strut driveshaft 20 and turbine
driveshaft 22. The strut 14 provides structural support of the RAT
10 and helps support the turbine assembly 12. In the illustrated
embodiment, the strut 14 has a hollow and generally cylindrical
shape. Moreover, in the illustrated embodiment, the generator 16 is
positioned at a proximal end of the strut opposite the turbine
gearbox assembly 12. It should be noted that the generator 16 is
merely one form of power conversion device that can be used with
the RAT 10, and is shown merely by way of example and not
limitation. For instance, a hydraulic pump can be used in place of
or in addition to the generator 16 in further embodiments. The
drivetrain 18 includes suitable shafts and gearing to provide a
mechanical connection between the turbine assembly 12 and the
generator 16, in order to transmit rotational energy (torque) to
the generator 16, as explained further below.
[0010] In the illustrated embodiment, the turbine assembly 12
includes turbine blades 24, a hub 26, and a locking mechanism 28.
The turbine assembly 12 can further include additional components
as desired, such as suitable pitch or speed control mechanisms
located within the hub 26. The turbine blades 24 are secured to the
hub 26, and can have adjustable pitch in some embodiments. During
operation, the turbine blades 24 can interact with airflows to
produce rotation of the hub 26. In one embodiment, the turbine
assembly 12 is configured to have an operating range of
approximately 3,800-5,000 RPM (or 63.33-83.33 Hz).
[0011] The hub 26 is secured to the turbine driveshaft 22, which
rotates at the same speed as the hub 26. The turbine driveshaft 22
is part of the drivetrain 18 and extends into a gearbox 30, which
can be located aft of the hub 16 and the turbine blades 24. The
gearbox 30 can be secured to and supported by a distal end of the
strut 14. The gearbox 30 contains suitable gearing of the
drivetrain 18 to provide a gear ratio to operate the strut
driveshaft 20. The locking mechanism 28 can be configured to
selectively insert a plunger into a mating feature (e.g., opening)
in the turbine driveshaft 22 to selectively stop rotation of the
turbine driveshaft 22, the hub 26, and other components engaged
therewith.
[0012] The strut driveshaft 20 is part of the drivetrain 18, and is
positioned at least partially within the strut 14. The strut
driveshaft 20 can directly engage the generator 16.
[0013] The RAT 10, in the illustrated embodiment, is configured to
be selectively deployable from fuselage of the aircraft using
suitable actuators (not shown). When deployed, the RAT 10 presents
the turbine assembly 12 to airflow passing the aircraft, and can be
used to generate desired forms of power using kinetic energy from
rotation of components of the turbine assembly 12 produced by the
passing airflow. The RAT 10 can be deployed in-flight to provide
emergency or secondary power. Because the general configuration and
use of RATs is well known, further discussion here is
unnecessary.
[0014] FIG. 2 is an enlarged perspective view of a portion of the
RAT 10, and FIG. 3 is a cross-sectional view of the portion of the
RAT 10, taken along line 3-3 of FIG. 2. As shown in the illustrated
embodiment, the strut driveshaft 20 extends into the gearbox 30 and
is rotatably supported relative to the gearbox 30 by two bearing
sets 32. A pinion gear 34 is attached to a distal end of the strut
driveshaft 20, and can be positioned in between the bearing sets
32.
[0015] In the illustrated embodiment, the turbine driveshaft 22
extends through the gearbox 30, and is rotatably supported relative
to the gearbox 30 by two bearing sets 36. A ring gear 38 is
attached to the turbine driveshaft 22, and meshes with the pinion
gear 34 to transmit power between the turbine driveshaft 22 and the
strut driveshaft 20 at a desired gear ratio. Splines 40 can be
provided in the turbine driveshaft 22 to form a "back drive"
connection for external tooling to be attached to the RAT 10 to
rotate the drivetrain 18 for maintenance and safety inspection
purposes. A pair of diametrically opposed openings 42 can be
provided in the turbine driveshaft 22 to allow engagement with a
locking member (e.g., plunger or pin) of the locking mechanism
28.
[0016] The turbine driveshaft 22 includes a flange 50 that can
interface with the hub 26. The flange 50 can be secured to the hub
26 with suitable bolts at or near a perimeter of the flange 50. The
flange 50 has a forward face (to the left in FIG. 3) that can be
arranged at an angle of approximately2.degree. (+/-0.25.degree.)
relative to an axis of rotation A, and has a rear face (to the
right in FIG. 3) that can be arranged at approximately 9.degree.
(+/-0.25.degree.). In this way the flange 50 can taper from a
thicker inner diameter portion to a thinner outer diameter portion.
The inner diameter portion of the flange 50 at a base of the taper
can have a wall thickness of approximately 2.240 cm (0.882 inches).
Extending rearward from the flange 50 of the turbine driveshaft 22
is a body portion that is tubular in shape with a hollow interior
cavity. An axial length L of the body portion of the turbine
driveshaft 22 can be approximately 22.715 cm (8.943 inches). The
tubular body portion of the turbine driveshaft 22 can include a
frusto-conical portion 54 (also called the shaft cone), which can
be located approximately 6.78 cm (2.67 inches) rearward from the
flange 50, with the turbine driveshaft 22 being substantially
cylindrical in shape between the flange 50 and the frusto-conical
portion 54. The frusto-conical portion 54 creates space to
accommodate one of the bearing sets 32 and the distal end of the
strut driveshaft 20. The frusto-conical portion 54 can be arranged
at approximately 14.degree. (+/-0.5.degree.) relative to the axis
A. A hub pilot diameter O1 can be defined adjacent to the forward
face of the flange 50, and can be approximately 18.001 cm (7.090
inches). An outer diameter O2 of the body of the turbine driveshaft
22 at the forward bearing set 36 can be approximately 7.117 cm
(2.802 inches) and a corresponding inner diameter O3 can be
approximately 4.994 cm (1.966 inches), resulting in a corresponding
wall thickness of approximately 2.123 cm (0.836 inches).
[0017] In one embodiment, a ratio of the outer diameter O2 of the
body of the turbine driveshaft 22 to the corresponding inner
diameter O3 can be in the range of approximately 1.423 to 1.425. In
one embodiment, a ratio of the outer diameter O2 of the body of the
turbine driveshaft 22 to the hub pilot diameter O1 can be in the
range of approximately 1.359 to 1.380. Further, in one embodiment,
a ratio of the inner diameter O3 of the body of the turbine
driveshaft 22 to the hub pilot diameter O1 can be in the range of
approximately 0.954 to 0.968.
[0018] Certain dimensions of the turbine driveshaft 22 are critical
to performance. In addition to the angles of the front and rear
faces of the flange 50 mentioned above, thicknesses of particular
portions of the turbine driveshaft are significant. Ratios of the
various dimensions discussed above can also be significant.
Together, the combination of these design parameters of the turbine
driveshaft 22 produces desirable vibration performance.
[0019] During operation, the RAT 10 is subject to various forces,
including torques, vibration and bending. The turbine driveshaft
22, in particular, must be able to transmit suitable torque loads,
and must have geometry and size characteristics that allow portions
of it to fit within the gearbox 30 and engage with other components
of the RAT 10. For instance, the turbine driveshaft 22 should be
able to interface with existing hubs 26 and interface with the
locking mechanism 28. Because the turbine assembly 12 is subject to
a variety of forces during operation, bending moments can be
imparted to the turbine driveshaft 22. It has been discovered that
lateral movement of the turbine driveshaft 22 in a direction in and
out of the page as shown in FIG. 3 can cause displacement between
the pinion gear 34 and the ring gear 38, which leads to torque
ripples through the drivetrain 18. Torque ripple is an increase and
decrease in torque transmission over time. The harmonic response
characteristics of the RAT can cause amplified lateral movment of
the turbine driveshaft through twisting of the RAT strut. By
increasing the lateral stiffness of the turbine driveshaft 22,
these large amplifications can be moved outside of the operating
range of the RAT and subsequently torque ripple can be reduced.
[0020] Any relative terms or terms of degree that used herein, such
as "substantially", "approximately", "about", "essentially",
"generally" and the like, should be interpreted in accordance with
and subject to any applicable definitions or limits expressly
stated herein. In all instances, any relative terms or terms of
degree used herein should be interpreted to broadly encompass any
relevant disclosed embodiments as well as such ranges or variations
as would be understood by a person of ordinary skill in the art in
view of the entirety of the present disclosure, such as to
encompass ordinary manufacturing tolerance variations and the
like.
[0021] While the invention has been described with reference to an
exemplary embodiment(s), it will be understood by those skilled in
the art that various changes may be made and equivalents may be
substituted for elements thereof without departing from the scope
of the invention. In addition, many modifications may be made to
adapt a particular situation or material to the teachings of the
invention without departing from the essential scope thereof.
Therefore, it is intended that the invention not be limited to the
particular embodiment(s) disclosed, but that the invention will
include all embodiments falling within the scope of the appended
claims.
* * * * *