USOO6676379B2

(12) United States Patent (10) Patent No.: US 6,676,379 B2

Eccles et al. (45) Date of Patent: Jan. 13, 2004

(54) RAM AIR TURBINE WITH SPEED 5.249,924. A 10/1993 Brum

INCREASING GEARBOX 5,484.120 A 1/1996 Blakeley et al.
5,487.645 A 1/1996 Eccles
(75) Inventors: Steven R. Eccles, Torrance, CA (US); 5,562.417 A 10/1996 Grimm et al.
Wayne G. Schindler, Huntington 5,564,903 A 10/1996 Eccles et al.
Beach, CA (US); Wei-Shing Chaing, 6,145,308 A 11/2000 Bueche et al.
6,420.808 B1 7/2002 Hosle Hösle
Diamond Bar, CA (US)
FOREIGN PATENT DOCUMENTS
(73) Assignee: Honeywell International Inc., EP O 045 264 2/1982
Morristown, NJ (US) EP O 712996 5/1996
(*) Notice: Subject to any disclaimer, the term of this EP 1046 838 10/2000
ded di d und
patent is extended or adjusted under 35 FR
WO 1173681
WO OO/17543 2/1959
3/2000
U.S.C. 154(b) by 0 days.
Primary Examiner Edward K. Look
(21) Appl. No.: 10/011,075 ASSistant Examiner-Dwayne J. White
(74) Attorney, Agent, or Firm-Oral Caglar, Esq.
(22) Filed: Dec. 6, 2001 (57) ABSTRACT
(65) Prior Publication Data
A ram air turbine power System includes a ram air turbine
US 2003/0108426 A1 Jun. 12, 2003 having a turbine Shaft, turbine blades for rotating the turbine
(51) Int. Cl. .................................................. F01D 7/02 shaft; and an electrical generator or other power Source
(52) U.S. Cl. ............................... 416/170 R; 415/122.1; device driven by a power Shaft, for providing power. The
416/142: 244/58 power shaft has a generally hollow tubular shape, and the
(58) Field of Search 416/170R 142 turbine
bine Shaft
shaf extends
d coaxially
iallv within th
the power Shaft. The
haft. Th
415/122.1, 1241; 74/52, 98,332, 393; ram air turbine power System also includes a gearbox
244/54, 56, 58 housing a planetary gear train, where one end of the gear
train is a planetary Sun gear Spline coupled to the power Shaft
56 References Cited and the other end of the gear train is a planetary ring gear
(56) spline coupled to the turbine shaft so that the rotating turbine
U.S. PATENT DOCUMENTS shaft drives the power shaft through the gear train increasing
2.986.219 A 5/1961 Boardman, Jr. et al.
the speed of the power shaft over the speed of the turbine
shaft.
4,578019 A 3/1986 Safarik
4,671,737 A 6/1987 Whitehouse
4,692,093 A 9/1987 Safarik 27 Claims, 4 Drawing Sheets
U.S. Patent Jan. 13, 2004 Sheet 1 of 4 US 6,676,379 B2

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U.S. Patent Jan. 13, 2004 Sheet 3 of 4 US 6,676,379 B2

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U.S. Patent Jan. 13, 2004 Sheet 4 of 4 US 6,676,379 B2
 US 6,676,379 B2
1 2
RAMARTURBINE WITH SPEED the RAT by keeping the turbine, the driven power source
INCREASING GEARBOX device, and gearbox components coaxial to improve overall
packaging of the RAT power System.
In one aspect of the present invention, a ram air turbine
BACKGROUND OF THE INVENTION power System includes a ram air turbine having a turbine
The present invention generally relates to ram air turbines shaft projecting rearward, and turbine blades for rotating the
of the type used on aircraft to drive backup electric or turbine Shaft; a power Source device having a rotatable
hydraulic power Systems and, more particularly, to a ram air power shaft for generating power in response to rotation of
turbine having an in-line Speed increasing planetary gearbox the power Shaft for providing a power Source. The power
for driving an electrical generator or hydraulic pump. shaft has a generally hollow tubular shape defining a rear
end, and the turbine shaft extends coaxially within the power
Ram air turbine power systems (RATS) are generally shaft and also has a rear end. The ram air turbine power
known in the aerospace industry for use in driving auxiliary System also includes a gearbox housing a gear train, where
power Systems in the event of a primary System failure. one end of the gear train is connected to the power Shaft near
Commercial aircraft manufacturers install RATS as an emer 15 the rear end of the power Shaft and the other end of the gear
gency form of power when the main engine generators or train is connected to the turbine Shaft near the rear end of the
hydraulic pumps are not operating. The ram air turbine turbine shaft so that the rotating turbine shaft drives the
power System is commonly Stored within the wing or power shaft through the gear train.
fuselage of an aircraft for deployment into the air Stream In another aspect of the present invention, a gearbox is
when needed. When called upon for electrical power, the adapted for inline driving of a power shaft by a turbine shaft
RAT is deployed into the air Stream, typically by Swinging in a ram air turbine power System having a ram air turbine
it out from its wing or fuselage compartment at the end of with turbine blades for rotating the turbine shaft and having
a Support Strut, and functions similar to a windmill by a power Source device where the power shaft defines front
extracting energy from the flowing air along the aircraft in and rear ends and is Supported to rotate within the power
flight. The ram air turbine portion of the RAT typically 25 Source device for driving a power generation apparatus to
includes two or more turbine blades adapted to be driven by provide a power Source. The gearbox includes a gear train
the air Stream, to provide a rotary output which can be used having a driven gear and a driving gear. The driven gear is
to drive an electrical generator, a hydraulic pump or both. connected to the power Shaft near the rear end of the power
Such ram air turbines are commonly equipped with a speed shaft and the driving gear is connected to the turbine Shaft
control governor for altering turbine blade pitch angle, or near the rear end of the turbine shaft whereby the rotating
feathering, to achieve a Substantially constant turbine rota turbine Shaft drives the driving gear, the driving gear rotates
tional Speed despite variations in air speed or load. to drive the driven gear through the gear train, and the driven
When designing aircraft components, important factors to gear drives the power shaft.
address are size, weight, and reliability. In an effort to reduce In yet another aspect of the present invention, a ram air
the physical size, also referred to as “envelope', of an 35 turbine power System includes a ram air turbine having a
electrical generator or other power Source device that is turbine shaft projecting rearward, and turbine blades for
driven by a RAT, one method is to increase the Speed at rotating the turbine shaft. The ram air turbine power System
which the generator or other power Source device operates. also includes an electrical generator for providing an elec
But the RAT turbine may have an optimum speed that is trical power Source. The electrical generator has a rotatable
slower than the increased generator Speed. Prior art, for 40 power shaft. The power shaft has a generally hollow tubular
example, U.S. Pat. No. 5,484,120, teaches the use of a gear shape defining a rear end, and the turbine shaft extends
train as a means of transmitting Shaft rotation up through a generally coaxially within the power Shaft and also has a rear
hollow support strut between the RAT turbine and a driven end. The ram air turbine power System also includes a
device at the top of the Support Strut within the aircraft, using gearbox housing an epicyclic Star gear System. The epicyclic
Spur gears and bevel gears. The use of Such a drive shaft 45 Star gear System has an output gear and an input gear, the
extending through the Support Strut to drive a power Source output gear may be a planetary Sun gear, which is spline
device within the aircraft is comparatively long and heavy coupled to the power shaft near the rear end of the power
relative to using a short drive Shaft to drive the power Source shaft, and the input gear may be a planetary ring gear, which
device adjacent to the RAT turbine, and the Spur gears and is Spline coupled to the turbine shaft near the rear end of the
bevel gears may Sustain a relatively high gear tooth loading, 50 turbine shaft, whereby the rotating turbine shaft drives the
detracting from reliability. The problem of reducing genera input gear, the rotating input gear drives the output gear
tor envelope and weight is not addressed. through a gear train, which may include planet gearS Sup
AS can be Seen, there is a need to reduce the envelope and ported on a Stationary bearing housing, and the output gear
weight of RATs while improving their reliability. There is drives the power shaft, whereby the power shaft rotates at a
also a need for reducing the envelope and weight of the 55 greater Speed than the turbine Shaft.
generator or other power source device driven by the RAT In Still another aspect of the present invention, a method
turbine. Moreover, there is a need for providing an efficient for power generation includes the Steps of, first, deploying a
arrangement of components in the RAT ram air turbine having a turbine Shaft projecting rearward,
SUMMARY OF THE INVENTION and turbine blades for rotating the turbine Shaft; Second,
60 using the ram air turbine to drive an electrical generator for
The present invention reduces the envelope and weight of providing an electrical power Source, the electrical generator
RATS while improving reliability by using a gear train with being driven by a rotatable power shaft, the power shaft
reduced tooth loads. The present invention also reduces the having a generally hollow tubular shape defining a rear end,
envelope and weight of the generator or other power Source the turbine Shaft extending generally coaxially within the
device driven by the RAT turbine by increasing the speed of 65 power Shaft and also having a rear end; and, third, driving
the power Source device. Moreover, the present invention the rotatable power Shaft of the electrical generator through
provides an efficient in-line arrangement of components in a gearbox including an epicyclic Star gear System, the
 US 6,676,379 B2
3 4
epicyclic Star gear System having an output gear and an input power System by keeping the ram air turbine, the driven
gear. The output gear may be a planetary Sun gear, Spline power Source device, and gearbox components coaxial to
coupled to the power shaft near the rear end of the power improve overall packaging of the ram air turbine power
shaft, and the input gear may be a planetary ring gear, Spline System. The in-line configuration is efficient in many
coupled to the turbine shaft near the rear end of the turbine respects, including mechanically, aerodynamically, and in
shaft, whereby the rotating turbine shaft drives the input terms of providing maximal power output for minimal
gear, the rotating input gear drives the output gear through weight and envelope. The planetary gear train which may be
a gear train, which may include planet gears, and the output provided in the Speed increasing gearbox facilitates the
gear drives the power Shaft, whereby the power shaft rotates in-line configuration by keeping the turbine, gearbox, and
at a greater Speed than the turbine Shaft. power unit components coaxial, contributing to the overall
These and other features, aspects and advantages of the efficiency, light weight, and low envelope of the ram air
present invention will become better understood with refer turbine power System. The in-line arrangement provided by
ence to the following drawings, description and claims. the planetary gear train has an overall size envelope that is
Smaller in comparison to both spur and bevel gear assem
BRIEF DESCRIPTION OF THE DRAWINGS 15 blies used in the prior art. System weight is also reduced in
FIG. 1 is a perspective view illustrating a ram air turbine comparison to the prior art.
with Speed increasing gearbox according to one embodiment Another advantage provided by one embodiment of the
of the present invention, deployed from an aircraft; present invention is Serviceability of the gearbox. The entire
gearbox can be inspected, or replaced, by Simply removing
FIG. 2 is a longitudinal Sectional view, taken generally on the back cover. The three planet gears and outer ring gear
the line 2-2 of FIG. 1, of a ram air turbine with speed may be Supported upon a Stationary bearing housing. The
increasing gearbox according to one embodiment of the bearing housing with attached gears can be easily bolted to
present invention; the generator housing. Additionally, a ground cart motor can
FIG.3 is a magnified longitudinal Sectional view, showing easily be attached to the aft of the gearbox for ground check
a portion of FIG. 2 in greater detail, of a ram air turbine with 25 and Spin up if required. The ground cart motor would only
Speed increasing gearbox according to one embodiment of need to rotate at the normal Speed of the ram air turbine,
the present invention; and approximately 4000 rpm, because the turbine Shaft projects
FIG. 4 is a croSS Sectional view, taken generally on the rearward, carrying the turbine Speed all the way through the
line 4-4 of FIG. 3 and of FIG. 2, of a speed increasing in-line assembly to the extreme aft end of the gearbox,
gearbox for a ram air turbine, according to one embodiment where the ground cart motor may be connected.
of the present invention. Referring now to FIG. 1, ram air turbine power system 10
DETAILED DESCRIPTION OF THE according to one embodiment of the present invention is
INVENTION illustrated deployed from an aircraft 12. Ram air turbine
power System 10 may be used to drive one or more auxiliary
The following detailed description is of the best currently 35 power Systems in aircraft 12. An in-line ram air turbine
contemplated modes of carrying out the invention. The power System similar to the one shown and described in
description is not to be taken in a limiting Sense, but is made FIG. 1 is disclosed in U.S. Patent entitled "In-Line Ram Air
merely for the purpose of illustrating the general principles Turbine Power System”, U.S. Pat. No. 5,564,903, issued on
of the invention, Since the Scope of the invention is best Oct. 15, 1996, and assigned to the assignee of the present
defined by the appended claims. 40 invention. The disclosure in that patent is hereby incorpo
The present invention reduces the envelope and weight of rated by reference into the present application. AS illustrated
ram air turbine power Systems (RATs), for use in aircraft or in FIG. 1, ram air turbine power system 10 may be sus
other applications where a wind or air flow driven power pended from aircraft 12 by means of strut 14 and includes a
Source is practicable, by using a gear train to increase the pair of turbine blades 16 projecting radially outwardly from
Speed of the power Source device. For example, the power 45 a rotary hub of ram air turbine 18. Ram air turbine 18 may
Source device may be an electrical generator driven by the include a speed control governor means (not shown in FIG.
ram air turbine. Increasing the Speed at which the electrical 1) of the type described, for example, in U.S. Pat. No.
generator is driven may allow reductions in both the enve 5,487,645, issued Jan. 30, 1996, entitled “Ram Air Turbine
lope and weight of the electrical generator, or other power With Secondary Governor,” which is assigned to the
Source device, while maintaining Substantially the same 50 assignee of the present invention and is incorporated by
power output. To increase the Speed of the power Source reference into the present application. The Speed control
device, an epicyclic Star gear System, also referred to as a governor means may be used, for example, for adjusting the
planetary gear train, may be provided in a gearbox also pitch angle of turbine blades 16 in a manner to achieve rapid
referred to as a Speed increasing gearbox. For example, in turbine acceleration to Substantially full Speed rotation,
one embodiment of the present invention, an optimal ram air 55 when ram air turbine 18 is deployed. Thereafter, the speed
turbine Speed is approximately 4,000 revolutions per minute control means maintains a Substantially constant turbine
(rpm) and an optimal electrical generator Speed is 12,000 Speed despite variations in air Speed or turbine load.
rpm So that a planetary gear train with an overall ratio of 3:1 Ram air turbine power system 10 is normally stored
is appropriate. The planetary gear train increaseS reliability within a Suitable compartment in the fuselage or wing of
of the ram air turbine power System by transmitting torque 60 aircraft 12. In the event of a primary power System failure,
through three planet gears, and reducing gear tooth loads, in ram air turbine power System 10 may be deployed quickly
contrast to the Spur gear and bevel gear arrangements used and easily by pivoting Strut 14 relative to mounting assem
exclusively for providing power transmission in prior art bly 20, thereby moving ram air turbine power system 10 to
ram air turbine power Systems, thereby lowering wear and an exposed position within the air Stream flowing past
incidence of failure of gear train components. 65 aircraft 12. In general terms, turbine blades 16 are rotatably
Moreover, the present invention provides an efficient driven by the Surrounding air Stream, to correspondingly
in-line arrangement of components in the ram air turbine drive ram air turbine 18, whereby turbine shaft 22 projecting
 US 6,676,379 B2
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rearward (as more clearly seen in FIGS. 2 and 3) provides The Second power Source device, or hydraulic pump in this
a rotary output for driving an auxiliary power unit, Such as example, may be connected directly to the turbine Shaft,
electrical generator 24 or a hydraulic pump (not shown in allowing the hydraulic pump to rotate at the slower turbine
any of the figures) or both. The hydraulic pump may be, for Speed while the electrical generator is allowed to rotate at the
example, a Swash plate pump, as known in the art. Electrical increased speed.
generator 24 may be driven through Speed increasing gear Also, as seen in FIGS. 1 and 2, the in-line ram air turbine
box 26. FIG. 1 illustrates the auxiliary power units, which power System 10, according to one embodiment, is carried
may be electrical generator 24 or a hydraulic pump, or both, at the lower end of strut 14, which may be hollow. Strut 14
and Speed increasing gearbox 26 arranged in an in-line is adapted, as known in the art, for pivotal movement
configuration with ram air turbine 18. relative to mounting assembly 20 between a normal stored
Referring now to FIG. 2, a longitudinal Sectional diagram position within the fuselage or wing of an aircraft, and a
of ram air power system 10 shows turbine shaft 22 may be downwardly protruding deployed position as illustrated in
rotatably Supported within bearings mounted in electrical FIGS. 1 and 2. Hollow strut 14 defines a passage 38 through
generator 24, or other power Source device, thereby avoiding which conductor cables 32 from electrical generator 24 may
a separate bearing carrier Structure disposed between ram air 15 pass to aircraft 12. Similarly, as in the examples given above
turbine 18 and electrical generator 24, or other power Source illustrating alternative or additional power Source devices,
device. The bearings may be provided in an arrangement to and in which a hydraulic pump is used as an example power
rotatably support power shaft 28 coaxially with turbine shaft Source device, hydraulic flow lines from the hydraulic pump
22. In order to dispose turbine shaft 22 and power shaft 28 may be conveniently passed through hollow Strut 14 to
coaxially with respect to one another, either one or both may aircraft 12. In addition, as may be desired, other mechanical
be fabricated in the form of a hollow tubular shaft. In the linkage Structures Such as a retractable release pin 40 for
embodiment illustrated in FIG. 2, both turbine shaft 22 and releasing ram air turbine 18 upon deployment may also
power shaft 28 are shown as hollow tubular shafts, with extend through hollow strut 14. With this construction, the
power shaft 28 coaxially disposed radially outwardly of entire ram air turbine power System 10, including Strut 14,
turbine Shaft 22. In the present example used to illustrate one 25 may have a desirable aerodynamic shape and may have
embodiment, in which the power Source device may include couplings, Such as conductor cables 32, and linkages, Such
electrical generator 24, power Shaft 28 may be appropriately as retractable release pin 40, protectively concealed against
asSociated with generator elements 30 for generating elec wind or other damage.
trical power which may be Suitably coupled via conductor Referring now to FIGS. 3 and 4, FIG. 3 illustrates a
cables 32 to aircraft 12. In general, power shaft 28 may be longitudinal Sectional diagram of gearbox 26, and FIG. 4
appropriately associated with power Source device elements illustrates a croSS Sectional diagram of gearbox 26. AS Seen
30 for generating power which may be suitably coupled to in FIG. 3, turbine shaft 22 projects rearward beyond rear end
aircraft 12 via appropriate power conducting means. Details 36 of power shaft 28. Turbine shaft 22 also has a rear end 34.
of a bearing System for Supporting ram air turbine Shaft 22 A Sun gear 42, of an epicyclic Star gear System may be
coaxially with power shaft 28 within a bearing system which 35 Splined, or otherwise Suitably mechanically coupled, to
may be mounted in an electrical generator, or other power power shaft 28, generally near rear end 36 of power shaft 28
Source device, are disclosed in U.S. Pat. No. 5,564,903, in the embodiment illustrated in FIGS. 3 and 4. Sun gear 42
referenced above. meshes with a set of planet gears 44 Supported by a
Turbine shaft 22 has rear end 34 which may be coupled, Stationary bearing housing 46. Stationary bearing housing
for example, by splines formed on turbine shaft 22, or by 40 46 with attached gears may be easily bolted, for example, to
other means, to one end of a gear train or other means, the housing of electrical generator 24, or other power Source
including direct coupling, for transmitting rotation to power device, using bolts 48.
shaft 28. Power shaft 28 has a rear end 36 which may be Stationary bearing housing 46 may also include lubrica
coupled, for example, by Splines formed on power shaft 28, tion passages, Such as lubrication passage 50. Lubrication
or by other means, to another end of a gear train or other 45 passage 50 is shown in the area of planet gears 44, additional
means, including direct coupling, for being rotated by tur passages forming part of a lubrication System would be
bine shaft 22. In one embodiment, as seen in FIG. 2, power drilled holes or tubes within gearbox 26. Although not
shaft 28 is rotatably driven through an epicyclic Star gear illustrated in FIGS. 3 and 4, the present invention contem
System, also referred to as a planetary gear train, by turbine plates that a lubrication System would be required. The
shaft 22. The epicyclic Star gear System is located within 50 lubrication System would include an oil Sump, Small pump,
gearbox 26 and is described in more detail below in con and additional lubrication passages. It is intended to alter
nection with FIG. 3. planetary gearbox cover 52 to form an oil Sump cavity. The
Many other possible embodiments and configurations in lubrication pump would be either a simple gear pump, or a
addition to that shown in FIG. 2 are contemplated by the "Gerotor' type pump, as known in the art. Both pump types
present disclosure. One or more alternate or additional 55 could be driven off the large planetary ring gear 54.
power Sources may be required. For example, and not by Planetary ring gear 54 meshes with and drives planet
way of limitation, a hydraulic pump may be required in gears 44, which mesh with and drive Sun gear 42. Planetary
addition to the electrical generator as shown in FIG. 2. If ring gear 54 of an epicyclic Star gear System may be splined,
both the electrical generator and hydraulic pump need to or otherwise Suitably mechanically coupled, to turbine Shaft
rotate at the same increased speed, the planetary gearbox 26 60 22, generally near rear end 34 of power shaft 28 in the
can be located just aft of ram air turbine 18 and forward of embodiment illustrated in FIGS. 3 and 4. For example,
the generator and pump. Another possible embodiment planetary ring gear 54 may be connected, as illustrated in
would be to mount a hydraulic pump, or other Second power FIG. 3, near rear end 34 of turbine shaft 22 through
Source device, aft of gearbox 26 in the in-line arrangement connector 56 which may be described as having the form of
shown in FIG. 2, to provide an in-line arrangement of a ram 65 a truncated cone connecting turbine Shaft 22 to planetary
air turbine followed by a first power source device followed ring gear 54. Planetary ring gear 54 may also be referred to
by gearbox 26 followed by a Second power Source device. as an input gear, as power is input to the epicyclic Star gear
 US 6,676,379 B2
7 8
System or planetary gear train of gearbox 26 at the ring gear a gear train having driven gear and a driving ring gear,
end of the gear train. Similarly, Sun gear 42 may also be Said driven gear connected to Said power Shaft gener
referred to as an output gear, as power is output from ally at the rear end of Said power shaft and Said driving
gearbox 26 at the Sun gear end of the gear train. ring gear connected to Said turbine shaft generally at
AS described above, many other possible embodiments the rear end of said turbine shaft whereby said turbine
and configurations in addition to that shown in the Figures shaft rotatable drives Said driving ring gear, Said driv
are contemplated by the present disclosure. For example, in ing ring gear rotatably drives Said driven gear through
addition to electrical generator 24, an embodiment may Said gear train, and Said driven gear drives Said power
further include a hydraulic pump connected to turbine shaft shaft.
22 either directly or indirectly through gearbox 26. By using 1O 9. The gearbox of claim 8 wherein said gear train is a
appropriate design and placement of the various Speed increasing gear train, whereby Said power shaft rotates
components, as will be apparent to a perSon of ordinary skill at a greater Speed than Said turbine Shaft.
in the art, a number of different in-line configurations could 10. The gearbox of claim 8 wherein said power shaft
be realized, a few of which have been described above. drives an electrical generator.
It should be understood, of course, that the foregoing 15 11. The gearbox of claim 8 further including a pump shaft
relates to preferred embodiments of the invention and that for a hydraulic pump, Said pump shaft connected generally
modifications may be made without departing from the Spirit in-line with said turbine shaft.
and Scope of the invention as Set forth in the following 12. The gearbox of claim 8 wherein said gear train
claims. comprises a planetary gear train.
We claim: 13. The gearbox of claim 12 wherein said driving ring
1. A ram air turbine power System comprising: gear comprises a gear Spline coupled to Said turbine Shaft.
a ram air turbine having a turbine shaft projecting 14. The gearbox of claim 12 wherein said driven gear
rearward, and turbine blades for rotating Said turbine comprises a planetary Sun gear Spline coupled to Said power
shaft; shaft.
a power Source device, disposed rearward of Said ram air 25 15. The gearbox of claim 12 wherein said gear train
turbine and having a rotatable power shaft, for gener further comprises a planet gear whereby Said driving ring
ating power in response to rotation of Said power Shaft gear rotatably drives Said driven gear through Said planet
for providing a power Source, Said power shaft having gear.
a generally hollow tubular shape defining a rear end, 16. A ram air turbine power System comprising:
Said turbine shaft extending generally coaxially within a ram air turbine having a turbine Shaft projecting
Said power shaft and having a rear end; rearward, and turbine blades for rotating Said turbine
a gearbox including a gear train having a ring gear, Said shaft;
gear train connected to Said power shaft generally at the an electrical generator, disposed rearward of Said ram air
rear end of Said power Shaft and Said ring gear of Said turbine, for providing an electrical power Source, Said
gear train connected to Said turbine shaft generally at 35
electrical generator having a rotatable power Shaft, Said
the rear end of said turbine shaft whereby said turbine power shaft having a generally hollow tubular shape
shaft rotatably drives said power shaft through said defining a rear end, Said turbine Shaft extending gen
gear train. erally coaxially within Said power shaft and having a
2. The ram air turbine power system of claim 1 wherein rear end; and
Said gear train comprises an epicyclic Star gear System. 40
a gearbox including an epicyclic Star gear System, Said
3. The ram air turbine power system of claim 1 wherein epicyclic Star gear System having an output gear and an
Said gear train is a Speed increasing gear train, whereby said input gear, Said output gear comprising a planetary Sun
power Shaft rotates at a greater Speed than Said turbine Shaft. gear Spline coupled to Said power shaft generally at the
4. The ram air turbine power system of claim 1 wherein rear end of Said power shaft and Said input gear
Said power Source device comprises an electrical generator. 45
comprising a planetary ring gear Spline coupled to Said
5. The ram air turbine power system of claim 4 further turbine shaft generally at the rear end of Said turbine
comprising a hollow Strut for Supporting Said ram air turbine shaft whereby said turbine shaft rotatably drives said
and Said electrical generator from an aircraft, Said generator input gear, Said input gear rotatably drives Said output
including an electrical line extending through Said hollow gear through a gear train comprising a planet gear, and
Strut to the aircraft. 50
6. The ram air turbine power system of claim 4 further Said output gear drives Said power Shaft, whereby Said
comprising a hydraulic pump having a pump shaft con power Shaft rotates at a greater Speed than Said turbine
shaft.
nected generally in-line with Said turbine Shaft. 17. A method for power generation comprising Steps of:
7. The ram air turbine power system of claim 6 further
comprising a hollow Strut for Supporting Said ram air 55 deploying a ram air turbine having a turbine Shaft pro
turbine, Said electrical generator, and Said hydraulic pump jecting rearward, and turbine blades for rotating Said
from an aircraft, Said electrical generator and Said hydraulic turbine shaft;
pump respectively including electrical and hydraulic lines using Said ram air turbine to drive an electrical generator,
extending through Said hollow Strut to the aircraft. disposed rearward of Said ram air turbine, for providing
8. In a ram air turbine power System having a ram air 60 an electrical power Source, Said electrical generator
turbine with turbine blades for rotating a turbine shaft and being driven by a rotatable power shaft, Said power
having a power Source device, disposed rearward of Said ram shaft having a generally hollow tubular shape defining
air turbine and having a power shaft defining a rear end and a rear end, Said turbine Shaft extending generally coaxi
rotatably Supported within Said power Source device for ally within Said power shaft and having a rear end; and
driving a power generation apparatus to provide a power 65 driving Said rotatable power shaft of Said electrical gen
Source, a gearbox for in-line driving of Said power Shaft by erator through a gearbox including an epicyclic Star
Said turbine Shaft, comprising: gear System, said epicyclic Star gear System having an
 US 6,676,379 B2
9 10
output gear and an input gear, Said output gear com 21. The ram air turbine power system of claim 18 wherein
prising a planetary Sun gear Spline coupled to Said Said planetary gear train is disposed in-line to Said power
power Shaft generally at the rear end of Said power Shaft shaft.
and Said input gear comprising a planetary ring gear 22. The ram air turbine power system of claim 18 wherein
Spline coupled to Said turbine shaft generally at the rear Said planetary gear train is disposed out of line to Said power
end of said turbine shaft whereby said turbine shaft shaft.
rotatably drives Said input gear, Said input gear rotat 23. The ram air turbine power system of claim 18 wherein
ably drives said output gear through a gear train com Said planetary gear train is disposed aft of Said ram air
prising a planet gear, and Said output gear drives Said turbine.
power shaft, whereby said power Shaft rotates at a 1O 24. The ram air turbine power system of claim 18
greater Speed than Said turbine Shaft. wherein:
18. A ram air turbine power System comprising: Said power Shaft is part of a first power Source device, and
a housing; Said planetary gear train is disposed forward of Said first
a ram air turbine having a turbine shaft driven by turbine 15
power Source device.
blades; 25. The ram air turbine power system of claim 18
a power shaft connected to Said turbine Shaft at the rear of wherein:
Said housing, and Said power Shaft is part of a first power Source device, and
a planetary gear train for transferring rotation from Said Said planetary gear train is disposed aft of Said first power
turbine Shaft to Said power Shaft with a ring gear of Said Source device.
planetary gear train being connected to Said turbine 26. The ram air turbine power system of claim 18 wherein
shaft. Said planetary gear train comprises a Sun gear coupled to
19. The ram air turbine power system of claim 18 wherein Said power shaft.
Said planetary gear train is disposed in-line to Said turbine 27. The ram air turbine power system of claim 18 wherein
shaft. 25 Said planetary gear train comprises Said ring gear Splined to
20. The ram air turbine power system of claim 18 wherein said turbine shaft.
Said planetary gear train is disposed out of line to Said
turbine shaft.