Note: Descriptions are shown in the official language in which they were submitted.
~, -1- 1 335647
This invention relates to methods and
apparatus for deicing leading edges, and more
particularly, pertains to the deicing of aircraft
leading edge surfaces such as on wings, struts,
stabilizers, and propellers. Specifically, this
invention relates to a fluid pressure intensifier
which may be employed in pneumatically actuated
deicers for use on leading edges.
This application is a division of Canadian
Application Serial No. 527,436 filed January 15, 1987.
Since the early days of powered aviation,
aircraft have been, from time to time, troubled by
accumulations of ice on component surfaces of the
aircraft such as wings and struts, under certain
flight conditions. Unchecked, such accumulations can
eventually so laden the aircraft with additional
weight and so alter the airfoil configuration of the
wings as to precipitate an unflyable condition. A
search for means to combat the accumulation of ice
under flying conditions has been a continuing one and
has resulted in three generally universal approaches
to removing accumulated ice, a process known
generically as deicing.
In one form of deicing, leading edges, that
is edges of the aircraft component on which ice
accretes and is impinged upon by the air flowing over
the aircraft and having a point at which this airflow
stagnates, are heated to loosen adhesive forces
between accumulating ice and the aircraft component.
Once loosened, this ice is generally blown from
the aircraft component by the airstream passing
over the aircraft. Two methods of heating
leading edges have enjoyed significant
~_ 1 335647
popularity. In one approach a heating element is
placed in the leading edge zone of the aircraft
component either by inclusion in a rubber boot
applied over the leading edge or by incorporation
into the skin structure of the aircraft component.
This heating element, typically powered by
electrical energy derived from a generating source
driven by one or more of the aircraft engines, is
switched on and off to provide heat sufficient to
loosen accumulating ice. In very small aircraft
powered typically by one or two engines, a
sufficient quantity of electrical power may be
unavailable for the use of electrical deicing.
In the other heating approach, gasses at
elevated temperature from one or more compression
stages of a turbine engine are circulated through
- leading edges of components such as wings and
struts in order to effect a thermal deicing or
anti-icing. Employed in aircraft powered by
turbine engines, the use of these so-called
compressor bleeds or by-pass streams from the
aircraft engine turbine can result in reduced fuel
economy and a lower turbine power output.
In limited situations a chemical is
applied to all or part of the aircraft to depress
adhesion of ice to the aircraft or to depress the
freezing point of water collecting upon surfaces of
the aircraft.
The remaining commonly employed method for
deicing is typically termed mechanical deicing. In
the principal commercial mechanical deicing means,
pneumatic deicing, the leading edge zone of a wing
or strut component of an aircraft is covered with a
plurality of expandable, generally tube-like
structures inflatable employing a pressurized
fluid, typically air. Upon inflation, the tubular
. ~
~3~ 1 335647
structures tend to expand the leading edge profile
of the wing or strut and crack ice accumulating
thereon for dispersal into the airstream passing
over the aircraft component. Typically, such tube
like structures have been configured to extend
substantially parallel to the leading edge of the
aircraft component. For airfoils such as wings and
stabilizers, these structures may extend the entire
span of the airfoil. A plurality of tube-like
structures frequently are positioned on a wing or
strut and typically are configured to be parallel
to the leading edge of the wing or strut as by
placement in a chord-wise succession away from the
leading edge. The plurality of tubes can provide
an ice removal function to the entire leading edge
profile of the airfoil or strut.
Conventionally, pneumatic deicers are
formed from a compound having rubbery or
substantially elastic properties. Typically, the
material forming tubes on such deicer structures
can expand or stretch by 40% or more during
inflation cycles causing a substantial change in
the profile of the deicer (as well as the leading
edge) and thereby cracking ice accumulating on the
leading edge. At least in part because of the
large volume of air required for inflating such
highly expandable tubes, the times for inflating
such tubes have typically historically averaged
between 2 and about 6 seconds.
The rubber or rubber like materials
forming these conventional pneumatic deicers
typically are possessed of a modulus of elasticity
of approximately 6900 kPa. Ice, as is well known,
is possessed of an elastic modulus enabling typical
ice accumulations to adjust to minor changes in
contours of surfaces supporting such ice
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accumulations. The modulus of elasticity for ice
is variously reported as being between about
275,000 ~Pa and about 3,450,000 kPa. The modulus
of elasticity of rubber compounds used in
conventional deicers however is substantially
different from the modulus of elasticity typically
associated with ice accumulations, and the large
expansion undergone by the deicer during inflation
functions to crack or rupture the structure of the
ice accumulations thereon allowing such
accumulations to be swept away by impinging wing
streams.
Ice accumulations, in conforming to minor
alterations in the contours of surfaces supporting
the ice accumulations do so only somewhat slowly.
The phenomenon by which ice accumulations conform
to changing contours of support surfaces in some
ways resembles the phenomenon of cold flow in
thermoplastic materials. Where the ice
accumulations are exposed to extremely rapid but
minor deformations, an ice coating cannot
accommodate such contour changes sufficiently
- rapid}y and shatters as though struck with a
hammer. More recently, it has been discovered that
a subjecting leading edges of a wing or a
stabilizer to electromechanical hammering, such as
is shown by U.S. Patent 3,549,964, can assist in
removing accumulations of ice on the leading edge.
Concern respecting the susceptibility of such
leading edges to stress fatigue upon being hammered
over extended periods of time as yet have
functioned to preclude substantial commercial
development of such electromechanical hammering
schemes.
A means for deicing a leading edge not
requiring the application of electrothermal deicers
.. . .
~ ~5~ 1 335647
and not requiring the application of pneumatic deicers
which, during the inflated state, substantially
distort the leading edge profile for an extended
period of time thereby interfering with the efficient
performance of the leading edge could find substantial
application in industry. Additionally, where such
means for deicing a leading edge do not pose a
significant likelihood for long term structural damage
due to stress such as is associated with
electromechanical hammering, such deicing means could
find substantial commercial utility.
In accordance with the invention there is
provided a fluid pressure intensifier comprising: i)
an inlet for a low pressure supply of the fluid; ii) a
I5 pair of piston chambers, one piston chamber being
substantially larger than the other together with
small and large piston surfaces associated therewith;
iii) conduit means for subjecting the smaller piston
chamber to the supply of low pressure fluid; iv) a
shuttle poppet; v) an indexer for the shuttle poppet;
vi) exhaust conduit means for communicating gaseous
fluid from the large piston chamber to a point
external to the intensifier, at least a portion of
said exhaust conduit means being carried by the
shuttle poppet, and a second portion being carried
otherwise upon the intensifier, the exhaust conduit
portions being alignable by movement of the shuttle
poppet; vii) a second source of low pressure fluid
configured to be alignable with the portion of the
exhaust conduit carried by the shuttle poppet upon
movement of the shuttle poppet to a predetermined
position; viii) an outlet; ix) a conduit means in
fluid transmitting relationship between the outlet and
the small piston chamber; and x) a biasing means for
biasing the shuttle poppet to and from the
predetermined position.
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There is described herein a method for
deicing an ice accreting surface and particularly a
leading edge surface. In the method, the surface of a
substantially high-modulus material accumulates ice.
According to the method, beneath this outer surface a
distortion means is provided of a size, position and
physical configuration suitable for distorting the
outer surface and placing a chord-wise strain upon
substantial portions of the outer surface upon
activation. The distorting means is periodically
activated to an extent sufficient to produce periodic
desirable distortion and chord-wise strain in the
outer surface sufficient to release accumulations or
accretions of ice thereon with the activation being
lS accomplished to the sufficient extent in not more than
about 0.25 seconds, more preferably in less than about
0.10 seconds and most preferably not more than 0.05
seconds. Preferably, the distortion means is an
inflatable means and preferably an inflatable means
activatible employing a fluid under pressure,
preferably a compressed gas such as air. However,
other distortion means can be employed in the practice
of the method of the invention, such as mechanical
lifters configured to distort the outer surface by
pressing or warping the outer surface away from a
resting profile of the surface.
Preferably, the distortion is induced in the
outer surface in a quite short time period, typically
100 milliseconds or less and most preferably in less
than about 50 milliseconds.. The distortion induced
preferably does not exceed about 0.5 centimeters and
preferably not more than about 0.25 centimeters.
There is also described herein an apparatus
for deicing an ice accreting surface such as a leading
edge surface which typically includes an outer surface
formed of a material having a substantially elevated
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modulus of elasticity upon which ice accumulates.
Preferably this elasticity modulus is at least 275,000
kPa and most preferably is at least as great as the
modulus of elasticity characterizing ice accumulating
upon the deicer surface.
The apparatus includes at least one
distortion means of a size, position, and physical
configuration whereby activation of the distortion
means distorts the outer surface of the deicer placing
a chord-wise strain upon substantial portions of the
outer surface. Preferably this distortion means is an
inflatable tubular member positioned beneath the outer
surface and activated employing a fluid under
pressure. Preferably this fluid is a compressed
gaseous material.
The apparatus includes a means for
triggering activation of the distortion means to
effectuate distortion of the outer surface. When
configured for use with an inflation means, this
activation means including a means for inflating the
inflatable member within not more than about 0.25
seconds, preferably not more than about 100
milliseconds, and most preferably not more than about
50 milliseconds. Where such distortion means is an
inflatable member, typically the apparatus includes a
means for deflating the distortion means following
inflation.
In preferred embodiments, where the
~ distortion means is inflatable, the apparatus includes a means for assuring against inflating the inflatable
tubular member to an extent in excess of that
necessary ~or providing desirable deformation and
chord-wise strain in the outer surface. Such an over-
inflation protection means for gaseous fluids
typically includes an accumulator fluid communication
with a source of gaseous fluid under pressure, the
l_ 1 335647
accumulator being of a particular size whereby release
of a gaseous accumulation from the accumulator into
the tubular member inflates the tubular member to a
desired extent.
Typically the inflation means by which an
inflatable member is caused to inflate is a solenoid
operated pilot valve of the invention, and preferably
the accumulator is incorporated into the structure of
such an inflation means.
Compressed gas for use in the practice of
preferred embodiments of the instant invention can be
obtained from a low pressure gas source such as a
compressor stage on an aircraft engine turbine through
use of an intensifier, in accordance with the
invention. Such an intensifier typically includes two
piston surfaces with one such piston surface being of
a smaller area than the other. Means are provided to
expose the smaller piston area to the low pressure gas
source whereby a cavity associated with the larger
piston area is evacuated by travel of the piston. A
poppet is provided with an indexing means whereby upon
evacuation of the large piston air chamber, the low
pressure gas source is applied to the large piston
chamber and the piston is caused to reverse and
compress gas occupying a chamber associated with the
smaller piston area. When a desired extent of
compression is achieved, the poppet is again shifted
whereby the large piston chamber can again be
evacuated, the low pressure gas is again applied to
the small piston chamber.
The above and other features and advantages
of the instant invention will become more apparent
when viewed in light of the description of the best
embodiment of the invention and the drawings which
follow, together forming a part of the specification.
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~ -9- 1 335647
Figure 1 is a side view in cross-section of
a deicer structure made in accordance with the
disclosure herein.
Figure 2 is a control schematic for
controlling activation of deicers in accordance with
the disclosure herein.
Figure 3 is a side elevational view in
cross-section of a pneumatic intensifier of the
invention.
Figure 4 is a side elevational view in
partial cross-section of an ejector/pilot operated
discharge valve suitable for use in the practice of
the method and apparatus described herein.
Figure 5 is a section view of an alternate
embodiment of a deicer described herein.
There is disclosed herein a method and
apparatus for deicing a leading edge. By deicing what
is meant is the removal of ice subsequent to formation
of the ice upon the leading edge. By leading edge
what is meant is that portion of a surface of a
structure which functions to meet and in substantial
measure break, an airstream impinging upon the
structure. Examples of leading edges would be forward
edge portions of wings, stabilizers, struts, nacelles,
and other housings and protrusions first impacted by
an airstream flowing over an aircraft in flight.
Referring to the drawings, Figure 1 depicts
a leading edge deicer 10.
The deicer 10 includes an outer surface
layer 12 or skin formed of a rigid material such as a
plastic or metal having a substantially elevated
modulus of elasticity or so-called Youngs modulus.
This modulus of elasticity should be at least 40,000
kPa. Preferably the modulus of elasticity is at least
as great as the modulus of elasticity associated with
ice accumulating upon the leading edge and preferably
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this modulus of elasticity is at least 275,000 kPa.
In most preferred embodiments it is believed that this
modulus of elasticity may be up to about 7,500,000 kPa
or greater.
An upper intermediate ply 14 and a lower
intermediate ply 16 are positioned beneath the skin
12. These plies 14, 16 are typically a fabric
material coated on one surface with a rubberizing
compound. In the upper intermediate ply 14, the
rubberizing coating faces in a direction outwardly
towards the skin 12 and is bonded to the skin 12.
1 335647
--10--
In the lower intermediate ply 16, the rubberizing
compound faces in a direction inwardly away from
the skin 12 whereby the fabric of the intermediate
plies 14, 16 co-operate to define an interstitial
space 18 between the plies 14, 16.
The fabric employed in the intermediate
plies 14, 16 may be of any suitable or conventional
nature. Preferably, a rayon, polyester, nylon or
acrylic fiber based fabric is employed. The
rubberizing compound can be of any suitable or
conventional nature such as natural rubber, styrene
butadiene or chloroprene rubbers suitable for
bonding to the outer skin 12 or to other structural
components of the deicer 10. Appropriate rubber
compounds are well known in the rubber compounding
field.
The plies 14, 16 are joined by mechanical
attachment such as heat sealing, chemical bonding,
adhesives, or, as shown in the drawing, by
stitching 19 at least one trailing edge 20 of the
deicer.
An inflatable member 24 and a bonding ply
26 are affixed to the lower ply 16 by adhesion,
vulcanized bonding to the rubberizing compound of
the lower intermediate ply 16 or other suitable or
conventional means. The bonding ply 26 typically
is configured of a rubber or rubber-like material
suitable for bonding to the skin of the aircraft.
Such compounds are well known in the art and the
selection of a particular compound will be
predicated upon a number of factors which may
include the nature of the aircraft skin to which
the deicer is mounted, and the relative cost and
availability of natural and synthetic rubbers. The
35 parameters influencing a selection of bonding ply -
material is well known in the rubber working art.
.
-11- 1 335647
Chloroprene such as Neoprene~ (duPont) and nitrile
rubbers are preferred as bonding ply materials.
The inflatable member 24 is a tube like
structure typically running the length of the
deicer and like the intermediate plies 14, 16
formed of a fabric material coated on one surface
with a rubberizing compound. The tube 24 is formed
whereby the surface coated with the rubberizing
compound faces outwardly from the center of the
inflatable member 24 and therefore defines an
inflation cavity 2~ within the tubular member 24.
An inflation conduit 30 is provided in fluid
communication with the inflation cavity 28 in
suitable or conventional well known manner. An
lS interstitial conduit 31 is provided in fluid
communication with the interstitial space 18
whereby the interstitial space 18 may be evacuated
employing a source of vacuum.
Only a single inflation member 24 is shown
in Figure 1 and should be understood that a
plurality of inflation members may be positioned
under the outer skin 12 and configured for inducing
distortion of the outer skin upon inflation. The
inflatable member 24 is of a size and shape such
that when inflated to a desired pressure, typically
between about 69 and about 276 kPa, the outer skin
is deformed above the tubular member to an extent
of not more than about 0.5 centimeters and
preferably not more than approximately 0.25
centimeters. The actual distortion required is a
function of the physical configuration of the
leading edge 10 and the nature of ice deposits
formed thereon. Typically such distortions are
desirable in a range of between 0.1 and 0.35
centimeters. Distortion of the outer skin pursuant
to inflation of the tubular member 24 produces a
- . ~ . . .. . .
-12- 1 335647
chord-wise strain depicted in Figure 1 by lines 35
in the outer skin 12 and this distortion and
accompanying chord-wise strain distorts to the
point developing stresses at the ice/skin interface
which serve to break the adhesive bond of the ice
to the skin, and developing cohesive fractures in
the ice itself due, it is believed, to an inability
of the ice to strain to the extent of the strain in
the skin to which the ice is attached.
The entire deicer 10 is bonded to the
aircraft skin in suitable or conventional well
known manner, but typically employing an adhesive
such as 3M part number 1300L.
Step-off filets 37, 38 are provided to
assure uniform smooth profile for the deicer 10.
The chord-wise strain depicted by the
lines 35 induces a certain very limited stretching
motion in the deicer outer skin 12. Stretching in
the outer skin 12 is limited because, unlike
conventional pneumatic deicers, the outer skin is
possessed of a high modulus of elasticity. High
modulus considerations are not important with
respect to the rubberized intermediate plies 14,
16, and the bonding ply 26 which are intended to be
substantially low modulus. Modulus considerations
are important only for the outer skin 12 which is
intended to be substantially high modulus.
Accordingly, the outer skin is formed of a
substantially high modulus material having an
ultimate elongation greater than about 3 0% and
most preferably greater than about 5.0%. By
elastic what is meant is capable of sustaining
deformation without permanent loss of size or
shape. The operational elongation to which the
outer skin 12 is subjected during distortion as a
result of chord-wise strain should be less than the
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1 335647
-13-
ultimate elongation inherent in the outer skin 12
material forming the outer surface of the deicer
otherwise premature failure of the outer skin 12
may occur. The operational elongation should also
be less than the fatigue strain for the material.
Fatigue strain is the elongation to which frequent
distortion produces material fatigue failure.
The outer skin 12 may be formed from
suitable or conventional materials such as metals
or plastics. Thin sheets of annealed stainless
steel and thin sheets of annealed titanium are
useful in the practice of the invention as an outer
skin 12. By thin what is meant is 0.00254 to about
0.0254 centimeters for metals and 0.008 centimeters
to 0.0508 for non metals. Likewise, plastics
having the characteristic of a high modulus of
elasticity and a suitable ultimate elongation find
utility in forming an outer skin. One plastic
material finding particular use in the practice of
the invention is polyetheretherketone (Peek)
available from ICI. Other suitable or conventional
plastic material such as polycarbonates, acetals,
nylons, polyesters, polyvinyl fluorides,
polyethylenes and the like can be employed in the
practice of the instant invention. Such materials
will possess an ultimate elongation greater than
about 3.0~ and preferably greater than about 5.0%
and an elastic modulus or Youngs modulus of at
least about 40,000 kPa and preferably at least
about 275,000 kPa but up to about 7,500,000 kPa or
more. The use of polymeric materials over metals
may be advantageous due to a lower tendency for ice
to adhere to such polymeric materials.
It should be apparent, referring to figure
1, that alternate means for deforming the surface
layer 12 can be employed other than an inflatable
' -
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tubular member 24. The inflatable member 24 can be
replaced by a bar activated employing a mechanical
lifter to deform the surface layer 12. Such
mechanical lifter can be activated employing a cam
like device, or a fluid activation system such as a
conventional hydraulic lifter mechanism.
Referring to Figure 5, an alternate
preferred embodiment of the invention is depicted
of a deicer 10 having an outer skin 12
characterized by a substantial modulus of
elasticity. The outer skin 12 is carried by a
rigid wing structure 120 having formed therein a
plurality of channels 122. The rigid wing
structure 120 includes points of contact 123
configured for supporting the outer skin 12 against
buckling as a result of air pressure encountered
during functioning of the outer skin 12 as a
leading edge for the wing structure 120.
The channels 122 are filled with a low
density liquid resistant to freezing such as an
alcohol. Periodically, the fluid within the
channels 122 is subjected to compressive force
which effectively inflates the channel 122 by
deforming slightly the outer skin 12 in an
outwardly direction. The pressure to which the low
density fluid is subjected is then released and the
deformation in the outer skin 12 is relaxed.
The rigid wing structure can be formed of
any suitable or conventional material such as
metal, or suitable or conventional reinforced
composites. The outer skin can be of thin sheets
of a annealed stainless steel or titanium or may be
a plastic material such as Peek. The points of
contact 123 may be finally drawn (point contacts or
line contacts) as depicted in Figure 5 or may form
a broader plateau upon which the outer skin 12 may
-15- 1 335647
rest for support. The particular configuration of
channels and points of contact will depend in part
upon the material selected for construction of the
rigid wing structure 120 and the outer skin 12. In
lieu of introducing a sudden pressurization of the
fluid contained within the channels 122, in an
alternate embodiment a pulse of fluid pressure may
be introduced to travel longitudinally along the
channels 122 through the fluid. This pulse would
have the effect of producing a momentary distortion
in the outer skin 12 as the pulse passes. This
momentary pulse could be generated by a simple
plunger piston in connection with the channels 122
driven by a motorized excentric. Alternately, a
timer driven solenoid admitting a pulse generated
by a high volume mechanically driven pump could be
employed to generate the pulse. The pulse must act
in the same relatively time span of less than .5
seconds and preferably less than 100 miliseconds
and most preferably less than about 50 milliseconds
in order to produce a desired deicing effect
employing a substantially high modulus or relative
rigid outer skin 12 as shown in Figure 5.
It is important that any such outer skin
12 deformation means function quickly. It is
desirable that the outer skin 12 be deformed within
about 0.250 seconds to assure effective ice removal
of thicknesses of 0.6 centimeters or less, and as
little as 0.05 centimeters in thickness.
micknesses greater than 0.6 centimeters, though
rarely encountered, are readily removed employing
the deicer of the invention. Preferably the
deformation occurs within about 100 milliseconds,
and most preferably the deformation is completed
substantially within about 50 milliseconds. This
rapid deformation functions effectively to blast
.
-16- 1 335647
the ice off of the outer skin 12 without givin~ the
ice accumulations an opportunity to conform
substantially to the changing surface contour of
the outer skin 12. Activation time significantly
in excess of about 1.0 seconds can result in
significant non-complete removal of ice from the
outer skin 12. Non-complete removal can
detrimentally effect performance of the component
being deiced.
Where the distortion means is a mechanical
device, rapid deformation is relatively readily
accomplished such as by the use of a cam device or
short stroke hydraulic actuators to press the outer
skin 12 outwardly. Where the deicer 10 includes a
tubular member 24 as shown in Figure 1, inflation
can be accomplished employing a fluid under
pressure. Where the fluid is a liquid, a device
having a capability for moving relatively
substantial quantities of pressurizing fluid in a
relatively short period of time is necessary to
assure inflation within the desired time
constraint. Where the inflation member 24 is
inflated pneumatically, a pneumatic source under
considerable pressure can be discharged into the
deicer in a manner causing virtually instant
inflation.
However, the introduction of fluid such as
air under a substantially elevated pressure into
the tubular member 24 without controls could result
in over-inflation of the deicer and resultant
damage to the leading edge structure. Accordingly,
it is preferable that the deicer in accordance with
the instant invention include a means for limiting
or controlling the extent to which the outer s~in
is distorted.
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For mechanical cams or hydraulic lifters,
well known means for limiting travel may suffice.
For liquid inflated tubular members 24 volume or
pressure limiters may function desirably. For
gaseous inflated tubular members 24, one such means
is by accumulating the gaseous fluid under pressure
in an accumulator of a physical size such that,
upon discharge of the accumulator, a carefully
determined quantity of air is released into the
inflatable member just 5ufficient to produce a
desired inflation and thereby desired degree of
distortion and chord-wise strain in the outer skin
12.
Equally, a means or device for reliably
insuring rapid and full discharge of any such
accumulator into the deicer is desirable.
Referring to the drawings, Figure 4 depicts a pilot
operated valve 50 including an accumulator 52
having an internal chamber 53 of a size configured
for storing an appropriate quantity of air under
under pressure for introduction into a tubular
member 24 like that shown in Figure 1. An inlet 54
is provided to the accumulator including an orifice
55 configured to build air pressure within the
accumulator relatively slowly. A pilot seat 56 is
provided opening into the chamber 53. The pilot
seat 56 is mounted upon a shaft 57 which includes a
spring biasing means 58. The shaft 57 is driven by
an electrical solenoid 59. Upon activation of the
solenoid, the pilot seat 56 is driven in a
direction toward the accumulator cavity 53 thereby
compressing the biasing spring 58. Upon release of
the solenoid 59, the biasing spring 58 functions to
return the pilot seat 56 to a closed position.
A main valve seat 61 is provided in a
surrounding relationship to the pilot valve seat
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56. The main valve seat is carried by a piston
62. A cavity 63 is presen~ adjacent the piston 62
and the piston 62 is biasly driven by a biasing
spring 64. An air bleed 66 joins the pilot valve
seat 56 with the main valve piston cavity 63
whereby high pressure air from the cavity 53 may be
applied to the cavity 63 by opening of the pilot
valve seat 56.
The air pressure applied at 63 over a
- 10 surface area of the piston 62 greater than the
surface area of the valve seat 61 functions to
drive the valve seat 61 open and allows a discharge
of air contained within the accumulator cavity 53.
Discharge from the cavity 53 is accomplished
employing exit ports 67. As pressure in the
accumulator cavity 53 drops, the biasing spring 64
functions to restore the main valve seat to a
closed position.
The valve 50 includes an ejector 69 of
suitable or conventional design and a vacuum
passageway 70 in communication with at least one of
the exit ports 67. The vacuum passageway 70 is in
air transmitting communication between a bleed
passage 71 and the ejector 69 whereby a vacuum may
be drawn on the exit port 67. By applying a source
of gas under relatively low pressure to the ejector
69 during those time periods when the pilot valve
and main valve seats are closed, a vacuum may be
drawn on the exit port, and thereby on the tubular
inflation member 24 depicted in in Figure 1. It
may be desirable to configure the interstitial
conduit 31 shown in Figure 1 to be in fluid
communication with the vacuum passageway 70 whereby
air present in the interstitial conduit 31 and
interstitial space 18 of Figure 1 may be
evacuated. Suitable or conventional well known
1 335647
conduit means may be employed for such
interconnections.
The orifice 55 in Figure 4 functions to
prevent a rebuilding of pressure within the
accumulator cavity 53 during discharge of the
accumulated cavity 53 in a manner so rapid as to
preclude the proper closing function of the valve
seats 56, 61.
Referrin~ to the drawings, Figure 2
1 depicts a schematic for a system 80 in accordance
with the invention for deicing wings and horizontal
stabilizers of an aircraft. The system 80 includes
a source 81 of low pressure air such as a
compressor or a bleed from a jet engine turbine
stage. The source 81 is joined to regulators 82,
83 for assuring a constant supply pressure of the
low pressure air source. The regulator 83 is
configured to supply low pressure air to the
ejector 69 depicted in Figure 4.
The regulator 82 supplies a constant
source of low pressure air to an intensifier 84
which boosts the pressure of the air arising from
the low pressure source 81 to a desirably elevated
pressure. An accumulator 85 is provided to receive
the high pressure air. This accumulator 85 can be
formed from suitable or conventional metal
construction or may be formed employing a high
strength fabric such as KEVLAR available from
duPont. By relatively low pressure what is meant
is air at a supplied pressure of between about 7
and 700 kPa. By the term high pressure what is
meant is a pressure of approximately 700 to about
12,000 kPa.
High pressure air in the main accumulator
85 is available through suitable conduits 86 to
accumulators associated with pilot valves such as
.
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the accumulator 52 depicted in Figure 4. Employing
a pilot operated valve 50 such as is depicted in
Figure 4, the high pressure air from the
accumulator is then made available to individual
wing and stabilizer deicer 87, 88, 89 having
inflatable members 24 such as are depicted in
Figure 1.
A control device 90 functions to control
the activation of the solenoids 59 associated with
the pilot operated valve 50 whereby timed release
of high pressure air to the inflatable members 24
of the deicers 87, 88, 89 can be accomplished.
Preferably, the control device 90 can, in part,
also determine the timing and magnitude of the
supply of air from the vacuum regulator 83 to
ejector 69 associated with the pilot operated
valves 50. Such control can be accomplished in
well known fashion.
It should be understood that the system 80
depicted in Figure 2 is exemplary only, and that
various modifications and alterations may be made
thereto in accommodating particular deicer and
valving physical configurations. In particular,
the low pressure source of air can be replaced by a
high pressure source of air such as from a
compressor or a storage gas bottle (not shown)
whereupon the intensifier may become superfluous.
Also, the vacuum regulator 83 and the regulator 82
may consist of a single unit supplying low pressure
air for vacuum production and for intensification.
The intensifier 84 as depicted in Figure 2
can be of a configuration such as is shown in
Figure 3. ~eferring to Figure 3, an intensifier 84
includes a piston 92 having a large 93 and a small
94 surface and functioning within a large 95 and a
small 96 piston cavity. An inlet 98 to he small
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cavity 96 includes an inlet check valve 99. An
outlet 100 from the small cavity 96 includes an
outlet check valve 101.
A shuttle poppet 105 is provided including
a passageway 106. Movement of the shuttle poppet
along an axis of the piston indexes the passageway
106 with a vent passageway 107 and a drive inlet
108.
A biasing spring 109 is provided for
re-indexing the poppet 105. The biasing spring 109
is activated by a shaft portion 110 of the piston
92 which, during compressive motion of the piston,
compresses the biasing spring 109 which exerts a
force against the poppet 105 tending to return the
poppet into alignment with the exhaust ports 107.
A poppet position indexer 111 is provided to resist
- the effect of the biasing spring 109 until a
desirably sufficient motion of the piston 92 has
been accomplished.
In operation, low pressure air is supplied
to the inlet 98 to fill the small piston cavity 96
and drive the piston until the large piston 93
encounters the poppet 105 and indexes the poppet
105 to align the passageways 106 with the drive
inlet 108. Low pressure air is then applied to the
large piston chamber 95 and drives the piston in a
direction compressing gas present in the small
piston chamber and causing the compressed gas to
exit the outlet 100. With increasing compression
action, the piston portion 110 compresses the bias
spring 109 to a suf~icient extent to overcome the
retaining action of the indexer 111 and the
passageway 106 is thereby again realigned at the
exhaust ports 107 for recycle operation.
3S The intensifier 84 and the pilot valve 50
typically are made of lightweight material such as
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aluminum. Portions of the intensifier 84 such as
the sealing surfaces and the pilot valve 50 may be
formed of other machinable material such as
lightweight plastics.
S While a preferred embodiment has been
shown and described in detail, it should be
apparent that various modifications may be made
thereto without departing from the scope of the
claims that follow.
.
