Note: Descriptions are shown in the official language in which they were submitted.
CA 02284819 1999-09-22
FILE, PIPE-I# THIS AMENDED
T.~X~ TRANSLATION
-1-
Multistage valve, more particularly, Cabin
Air Exhaust Valve in an Aircraft,
and Method for Cabin Pressurization
The present invention relates to a multistage valve, more
particularly a cabin air exhaust valve in an aircraft,
the invention also relating to a method for cabin
pressurization in an aircraft.
Multistage valves, more particularly cabin air exhaust
valves in a cabin pressurization system of an aircraft,
pressurize the cabin in a defined range vital to the
safety of the persons on board and offering them maximum
comfort. These multistage valves provide occupants with
the partial pressure of the oxygen corresponding to the
flight altitude. Actuating the multistage valves enables
the cabin exhaust air mass flow to be regulated and
varied.
It is known to make use of two separate valves for cabin
pressurization, these valves being controlled so that one
of the valves opens at a higher differential pressure,
i.e. in. high-altitude flight, whilst the second valve
remains closed, it not being until low differential
pressures exist, i.e. in low-altitude flight or on the
ground, that the second valve also opens. Although this
valve arrangement permits sufficiently good regulation of
the cabin exhaust air mass flow the valving is
complicated in configuration and is accordingly
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2
relatively cost-intensive in production. In addition to
this the two valves need to be actuated via independent
drive mechanisms.
A further known valve for cabin pressurization in
an aircraft comprises a valve having a single flap which
depending on the differential pressure existing between the
cabin and the outer environment is opened correspondingly
wide. Although such an arrangement simplifies design, other
drawbacks are involved in such valving. It is usually the
case that the exhaust air mass flow of the valve achieves an
additionally effective boost in thrust. Such a boost in
thrust can only be achieved with difficulty in a single-flap
valve since the air mass flow cannot exhaust sufficiently
channellized and oriented.
On the basis of cited prior art the present
invention is based on the object of sophisticating a
multistage valve, more particularly a cabin air exhaust
valve in an aircraft such that the drawbacks as cited in
prior art are obviated.
More particularly it is intended to provide a
multistage valve which is simple and cost-effective in
manufacture and with which an effective boost in thrust is
possible by the exhaust air mass flow.
According to a broad aspect of the invention,
there is a multistage valve, more particularly a cabin air
exhaust valve in an aircraft, comprising a smaller first
valve stage, a larger second valve stage, and a drive
mechanism, said first valve stage and said second valve
stage being operatively connected to said drive mechanism;
said drive mechanism being constructed
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2a
and arranged to actuate and always open said first valve
stage prior to and separately from the subsequent actuation
and opening of said second valve stage.
According to another broad aspect of the present
invention, there is a method for cabin pressurization in an
aircraft, more particularly in an airplane, comprising the
following steps: a) providing a multistage valve having a
smaller first valve stage and a larger second valve stage
arranged in a common valve port and connected to a common
drive mechanism for opening said valve stages, separately
with the first valve stage opening prior to the second valve
stage; b) operating said drive mechanism for actuating and
opening said first valve stage for partially opening the
valve port to pressurize the cabin during flight at a high
differential pressure; and c) operating said drive mechanism
for actuating and opening the second valve stage after
opening the first valve stage and in addition to the opening
of the first valve stage for fully opening the valve port
during flight at a low differential pressure.
In accordance with a further aspect of the present
invention a method is provided, permitting simple and
effective means of cabin pressurization in an aircraft.
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The object is achieved in accordance with the invention
by a multistage valve, more particularly cabin air
exhaust valve in an aircraft, comprising a smaller first
valve stage and a larger second valve stage and a drive
mechanism, the first valve stage and the second valve
stage being connected to the drive mechanism such that
the first valve stage is actuated separately from the
second valve stage.
The multistage valve in accordance with the invention
comprises two valve stages actuated via a single drive
mechanism. Configuring and regulating the multistage
valve in accordance with the invention results in an
enormous increase in the economy of air-conditioning the
cabin of the aircraft. This is particularly of importance
since the air supply on board an aircraft, more
particularly an airplane, is the largest secondary energy
consumer. Furthermore, by separately actuating the
smaller first valve stage and the larger second valve
stage the air mass flow is able to exhaust from the
multistage valve such that a high effective boost in
thrust is achieved during flight. For this purpose, in
high-altitude flight, i.e. when a high differential
pressure predominates between the cabin interior and the '
outer environment, only the smaller first valve stage is
opened from which the air mass flow is able to exhaust
oriented and channellized. In low-altitude flight, i.e.
when a low differential pressure predominates between the
cabin interior and the outer environment, the second
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larger valve stage is opened so that a sufficiently large
aperture is available for exhaust of the air mass flow.
Advantageously the first valve stage and/or the second
valve, stage are configured plate-shaped.
In one advantageous aspect of the invention the first
valve stage and the second valve stage are arranged in a
valve port. In this way only a single valve port is
needed in the fuselage of the aircraft which furthermore
reduces the expense of production and assembly.
In accordance with one preferred embodiment of the
invention the first valve stage is arranged within the
second valve stage.
In such an aspect of the multistage valve both valve
stages may be pivoted to advantage about a single spindle
which reduces the design expense of the multistage valve.
Furthermore, it is possible in such an arrangement of the
two valve stages that they are oriented within a single
plane in both the fully open and fully closed setting of
the multistage valve to thus ensure an oriented exhaust
air mass flow with which in addition an effective boost
in thrust is achieved for low actuating forces.
Advantageously the first valve stage may be configured
rectangular and/or the second valve stage may comprise a
round base geometry. The round base geometry of the
second valve stage permits simple and cost-effective
production and in addition makes it possible to simply
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adapt the multistage valve in the valve port of the
aircraft fuselage whilst achieving an advantageous
sealing effect.
The contour of the smaller first valve stage as well as
the inner shape of the larger second valve stage are
configured aerodynamically condusive, more particularly a
maximum boost in thrust being achieved for a minimum
torque requirement.
In accordance with another embodiment of the present
invention the first valve stage and the second valve
stage are arranged in sequence.
Here ,again, both valve stages are arranged within a
single valve port in the fuselage of the aircraft thus
ensuring cost-effective production and assembly of the
multistage valve. Furthermore, it is achieved by the
arrangement of the valve stages in accordance with the
invention that the two valve stages are oriented in a
single plane in the fully closed condition of the
multistage valve, whilst the two valve stages are
oriented parallel to each other in the fully open setting
of the multistage valve. By a corresponding arrangement
of the valve stages a maximum boost in thrust is
achievable. It is furthermore possible to select the
fulcrums of the valve stages individually, thus requiring
only minimum actuating forces to open and close the
multistage valve.
J
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Advantageously the first valve stage and/or the second
valve stage is configured rectangular.
In yet another advantageous aspect of the invention the
drive mechanism is configured as a linkage mechanism
comprising at least two links each rotatably connected to
the other.
Linkage mechanisms are characterized by their links
moving in parallel planes due to their rotative
connection. The advantages of linkage mechanisms as
compared to other mechanisms are due to the links being
simple and thus cost-effective to produce, the relative
points of contact in the pivots as well as the resulting
high loading capacity of the linkage mechanism. In
addition, a broad pallet of many and varied applications
exists for linkage mechanisms, especially due to their
wealth of various structures, shapes and movement
possibilites. This is the reason why linkage mechanisms
can be adapted to practically any requirements as to
application and space availability by suitably selecting
the number of links and their geometric configuration.
Advantageously the at least two links are connected to
each other via pivots.
In one advantageous aspect the drive mechanism comprises
four links.
Configuring the drive mechanism with four links achieves
more particularly a uniform rotary movement of the drive
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unit being converted into a non-uniform rotary movement
of individual valve stages, resulting in differing
opening angles of the individual valve stages. Despite
the non-uniform rotary movements of the individual valve
stages it is nevertheless achieved that the two valve
stages in both the fully open and fully closed setting
are oriented in the same position.
In accordance with the invention the first valve stage
and the second valve stage may be arranged such that they
are oriented in the same position when fully open and
fully closed to thus achieve that the exhaust air mass
flow is opposed by only a minor resistance of the valve
stages in the open setting. In this arrangement the two
valveV stages - depending on the embodiment of the
multistage valve - may form in these-settings for example
a single plane or line or, however, may be oriented
paralle l to each other. It is especially in the closed
setting, however, that the two valve stages need to be
oriented in a single plane to achieve an adequate sealing
effect of the multistage valve.
In another advantageous aspect the drive mechanism
comprises three links, as a result of which, designing
the drive mechanism is simplified.
In accordance with yet another improvement the multistage
valve is provided with a frame surrounding the valve
port. This frame channelizes the exhaust air flow from
the multistage valve and improves the exhaust air flow.
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Preferably the frame is provided in a curved portion
serving as the contact surface area for the first valve
stage. On opening and closing the first valve stage the
latter slides by a correspondingly shaped section alqng
the curved portion of the frame to thus achieve reliable
guidance of the first valve stage.
Preferably the first valve stage and the second valve
stage are arranged such that on opening of the first
valve stage an aperture materializes facing away from the
second valve stage. An exhaust air mass flow from this
aperture does not press against the second valve flap,
thus enabling it to be actuated with less force. This
reduces the torque needed to actuate the multistage valve
so that less driving energy needs to be made available.
At the same time smaller and lighter drive elements may
be employed.
Preferably the first valve stage in the fully open
condition is remote from the valve port, as a result of
which the maximum size of the valve port is enlarged so
that exhaust of an air mass flow is facilitated. At the
same time the first valve stage ensures in its fully open
setting that the exhaust air mass flow is channellized.
With the multistage valve in accordance with the
invention as described above valuing is provided with
which the first valve stage and the second valve stage
are actuated by a single drive mechanism and wherein a
J
smaller first valve stage finds application as the
pressurization stage during flight at a high differential
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_g_
pressure and the larger second valve stage additionally
opens at a lower differential pressure.
In accordance with a further aspect of the present
invention a method is provided for cabin pressurization
in an aircraft, more particularly in an airplane, via a
multistage valve as described above, this method
comprising the steps:
a) actuating the smaller first valve stage as the
pressurization stage via the drive mechanism during
flight at a high differential pressure; and
b) additionally actuating the larger second valve stage
via the drive mechanism during flight at a low
differential pressure
the first valve stage being actuated separately from the
second valve stage
By the method in accordance with the invention it is
achieved that due to the exhaust air mass flow during
flight a maximized effective boost in thrust is attained.
As regards the advantageous effects and the way in which
these are achieved in the method in accordance with the
invention reference is made to the comments as given
above regarding the multistage valve in accordance with
the invention.
In another advantageous aspect of the method the first
valve stage and the second valve stage are driven by the
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drive mechanism such that they are oriented in the same
position when fully open and fully closed.
In accordance with yet another aspect of the present
invention the multistage valve in accordance with the
invention as described above is employed as a cabin air
exhaust valve in a cabin pressurization system of an
aircraft, more particularly of an airplane.
The invention will now be detailled by way of example
embodiments with reference to the drawing in which
Fig. 1 is a cross-section through a multistage valve in
accordance with a first embodiment of the
invention, the valve stages being illustrated in
the closed setting;
Fig. 2 is a cross-section through the multistage valve
as shown in Fig. 1, the smaller first valve
stage of which is illustrated open;
Fig. 3 is a cross-section through the multistage valve
as shown in Fig. 1, both valve stages of which
are illustrated fully open;
Fig. 4 is a cross-section through a multistage valve in
accordance with a second embodiment of the
invention, both valve stages of which are
illustrated fully closed;
Fig. 5 is a cross-section through the multistage valve
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as shown in Fig. 4, the smaller first valve
stage of which is illustrated open;
Fig. 6 is a cross-section through the multistage valye
as shown in Fig. 4, both valve stages of which
are illustrated fully open;
Fig. 7 is a cross-section through a multistage valve in
accordance with a third embodiment of the
invention, both valve stages of which are
illustrated closed;
Fig. 8 is a cross-section through the multistage valve
as shown in Fig. 7, the smaller first valve
stage of which is illustrated open; and
Fig. 9 is a cross-section through the multistage valve
as shown in Fig. 7, both valve stages of which
are illustrated fully open.
Illustrated in the Figs. 1 to 3 is a first example
embodiment of the invention.
Referring now to Fig. 1 there is illustrated a multistage
valve 10 in a valve port 11 of an aircraft. The
multistage valve 10 comprises a smaller first valve stage
20, a larger second valve stage 30 as well as a drive
mechanism 40. The first valve stage 20 is arranged within
the second valve stage 30. Both the first valve stage 20
and the second valve stage 30 are arranged rotatable in
the multistage valve 10 via a common spindle 22. The
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second valve stage 30 comprises a round base geometry,
whilst the first valve stage 20 is configured
rectangular. In any case the first valve stage 20 and the
second valve stage 30 are configured such that they
feature an aerodynamically condusive configuration.
The second valve stage 20 comprises ends 32 oriented in
the direction of the valve port 11. The ends 32 are
provided slightly rounded so that the second valve stage
30 has facilitated rotatation in the valve port 11.
Furthermore the valve port 11 is provided with slightly
recessed edges to additionally improve the rotatability
of the second valve stage 30.
The second valve stage 30 comprises an aperture 31 in
which the first valve stage 20 is rotatably arranged. The
walls 33 of the valve stage 30 in the region of the
aperture 31 are configured slanting and each comprises a
cutout 34 accommodating the ends 21 of the first valve
stage 20 in the closed setting of the multistage valve
10. Sealing elements may be provided in the cutouts 34.
The first valve stage 20 has approximately the shape of a
parallelogram, the first valve stage 20 comprising in the
region -of its spindle 22 its maximum diameter and
converging at an acute angle to the ends 21. By this
configuration of the first valve stage 20 it is achieved
that the ends 21 in the closed setting of the multistage
valve come into contact with the walls 33 and cutouts 34,
r
in which sealing elements may be provided, of the second
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valve stage 30 so that no air mass flow can exhaust from
the multistage valve 10.
The smaller first valve stage 20 and the larger second
valve stage 30 are driven via a single drive mechanism
40. The drive mechanism 40 comprises a total of four
links 41, 42, 43, 44 each connected to the other
rotatably via pivots 45. The first valve stage 20 is
connected to the bone-shaped link 41 via a fastener
portion 23. The first valve stage 30 is connected to the
bone-shaped link 42 via a fastener portion 35. The links
41, 41 are indirectly connected to each other via links
43, 44. The drive unit (not shown) of the drive mechanism
40 is connected to the drive mechanism in the connecting
portion of the links 43 and 44.
The incident flow of the multistage valve 10 is in the
direction of the arrow L.
The functioning of the multistage valve 10 will now be
detailled with reference to the Figs. 1 to 3. In Fig. 1
the multistage valve 10 is illustrated in the closed
setting. Both the first valve stage 20 and the second
valve stage 30 are accordingly in the closed setting. Due
to the fact that the ends 21 of the first valve stage 20
are in contact with the walls 33 and the cutouts 34, in
which sealing elements may be provided, of the second
valve stage 30, the air mass flow is unable to exhaust
from the multistage valve 10.
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Referring now to Fig. 2 there is illustrated the
multistage valve 10 with the open first valve stage 20.
One such setting of the multistage valve 10 occurs, for
example, when the aircraft is cruising, i.e. flying .at
high, altitudes. When the aircraft is cruising a high
differential pressure predominates between cabin interior
and the outer environment of the aircraft. To generate an
effective air mass flow resulting in an effective boost
in thrust it is sufficient that only the first valve
stage 20 is open whilst the second valve stage 20 remains
closed when a high differential pressure exists. To
achieve such a positioning of the two valve stages 20, 30
of the multistage valve 10 the drive mechanism 40 is
turned in the direction of rotation as indicated by the
arrow D. Since the first valve stage 20 is connected to
the link 41 of the drive mechanism 40 rotatably but
nevertheless fixedly via the fastener portion 23, a
movement of the drive mechanism as indicated by the arrow
D results in opening of the first valve stage 20. Due to
employing a drive mechanism 40 having a total of four
links the uniform rotary movement of the drive mechanism
(not shown) for the drive mechanism 40 is converted into
a non-uniform rotary movement of the individual valve
stages 20, 30. This results in differing opening angles
of the valve stages. In the present example embodiment,
due to. the correspondingly selected links, more
particularly as regards their length, angular setting and
positioning it is achieved that the first valve stage 20
can be opened by actuating the drive mechanism 40,,whilst
the second valve stage 30 remains closed. In the
illustration as shown in Fig. 2 the first valve stage 20
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has opened sufficiently so that not only an advantageous
control .of the exhaust air mass flow is assured but also
that at the same time an effective boost in thrust is
achieved for low actuating forces, The second valve stage
30 continues to remain closed so that no air mass flow
can exhaust.
When a low differential pressure predominates between the
cabin interior and the outer environment of the aircraft,
for example in low-altitude flight or on the ground, it
is necessary that the air mass flow is able to exhaust
through a sufficiently large opening. This is why at low
differential pressures the multistage valve 10 needs to
be fully open, as is illustrated in Fig. 3. Due to the
drive~mechanism 40 being turned further in the direction
of the arrow D the links 42, 44 noui in contact with the
second valve stage 30 are shifted, as a result of which
the second valve stage 30 is also opened. In the fully
open setting of the multistage valve 10 as shown in Fig.
3 the two valve stages 20, 30 are oriented in a single
plane or line so that the air mass flow encounters
minimum resistance by the existing low differential
pressure. A maximum opening for exhausting the air mass
flow continues to be generated by the setting of the
multistage valve 10.
In Figs. 4 to 6 a further example embodiment of the
multistage valve in accordance with the invention is
illustrated.
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Referring now to Fig. 4 there is illustrated the
multistage valve 50, again arranged in a valve port 51 of
an aircraft fuselage. The multistage valve 50 comprises a
first valve stage 60, a second valve stage 70 as well , as
a drive mechanism 40. The drive mechanism 40 corresponds
in its configuration to that of the drive mechanism as
illustrated in Figs. 1 to 3 so that like components, or
like in function, are identified by like reference
numerals, without a repeat detailled description of the
drive mechanism 40. The first valve stage 60 and the
second valve stage 70 each having a rectangular base
geometry are arranged in sequence in the valve port 51.
The smaller first valve stage 60 is configured plate-
shaped and rotatably arranged in the multistage valve 50
via a spindle 61 and a fastener portion 62. The first
valve stage 60 comprises a baseplate 65, a guide plate 66
as well as an end portion 64 oriented in the direction of
the wall of the valve port 51, Provided in the free end
of the end portion 64 is a fastener section 67 via which
the first valve stage 60 is rotatably connected to the
link 41 of the drive mechanism 40. The guide plate 66
guiding the air mass flow and the baseplate 65 are
arranged inclined to each other and merge in an end
portion. 63 configured in the direction of the second
valve stage 70.
The second valve stage 70 is rotatably arranged in the
multistage valve 50 via a spindle 71 as well as.via a
fastener portion 72. The second valve stage 70 too, is
configured plate-shaped and comprises an end portion 74
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oriented in the direction of the wall of the valve port
51, a baseplate 75 and a guide plate 76 guiding the air
mass flow, as well as a fastener plate 77. Provided at
the fastener plate 77 is a fastener section 78 via which
the second valve stage 70 is connected rotatably with the
link 42 of the drive mechanism 40. The guide plate 76
which in the closed condition of the multistage valve 50
comes into contact with the end portion 63 of the first
valve stage 60 comprises in the portion in which the end
portion 63 of the first valve stage 60 is in contact with
the guide plate 76 of the second valve stage 70 an
additional sealing element 79. As shown in Fig. 4 the end
portion 63 of the first valve stage 60 is forced against
the sealing element 79 of the second valve stage 70 in
the closed condition as a result of which any exhaust of
the air mass flow in the closed condition of the
multistage valve 50 is reliably and totally avoided.
Furthermore, the guide plate 76 comprises a beaded
widened end 73. The end 73 has the task of diverting the
air mass flow in the open condition of the multistage
valve 50 to the guide plate 76. The beaded configuration
of the end 73 is not, however, mandatory, i.e. other
configurations of the guide plate being just as
conceivable, as long as the valve stages are configured
aerodynamically condusive.
The end portions 64 and 74 of the first valve stage 60
and second valve stage 70 opposite the wall of the valve
port 51. are configured slightly rounded to facilitate
rotation of the first valve stage 60 and second valve
stage 70 within the valve port 51. Furthermore, the
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fulcrums of the first valve stage 60 and the second
valve stage 70 defined by the spindles 61, 71 and the
fastener portions 62, 72 may be selected as a function of
the size of the valve stages and the requirements of the
application such that only minimum actuating forces are
needed to open and close the multistage valve 50.
The incident flow of the multistage valve 50 is in the
direction of the arrow L.
The functioning of the multistage valve 50 will now be
detailled with reference to the Figs. 4 to 6.
In Fig. 4 the multistage valve 50 is illustrated in the
closed position. Both valve stages 60 and 70 are in their
fully closed setting. In this arrangement the two valve
stages 60 and 70 are oriented in a single plane and thus
in the same position. To prevent exhaust of the air mass
flow existing in the interior of the cabin of the
aircraft from the step valve 50 the inclined end portion
63 of the first valve stage 60 is firmly urged in contact
with the likewise inclined guide plate 76 of the second
valve stage 70. In addition to this, the additional
sealing element 79 is provided in this portion to ensure
total sealing of the multistage valve.
Referring now to Fig. 5 there is illustrated the
multistage valve 50 with the first valve stage 60 open.
This valve setting is selected when the aircraft is
cruising., i.e. when a high pressure differential
predominates between the cabin interior and the outer
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environment of the aircraft. The first valve stage 60 is
open so far that not only control of the exhaust air mass
flow is assured but also at the same time a maximum boost
in thrust is achieved by the exhaust air mass flow. The
second valve stage 60 continues to be closed so that no
air mass flow can exhaust. The air mass flow is deflected
by the end 73 of the second valve stage 70 and
channellized by the inclined guide plates 66 and 76.
Opening the first valve stage 60 is done by rotatation of
the drive mechanism 40 in the direction of the arrow D.
Referring now to Fig. 6 there is illustrated the
multistage valve SO in its fully open setting. This open
position of the multistage valve 50 is selected when only
a low differential pressure predominates between the
cabin interior and the outer environment of the aircraft
as is the case, for example, in low-altitude flight or on
the ground.
Although both the first valve stage 60 and the second
valve stage 70 in the fully open setting are again
oriented in the same position, unlike the situation in
the example embodiment as shown in Figs. 1 to 3, however,
in the present example embodiment they are not oriented
in the .same plane, but parallel to each other. This
orientation of the two valve stages 60, 70 also achieves
that the air mass flow is confronted only by a minimum
resistance. At the same time as large an opening as
possible is provided from which the air mass flow is able
to exhaust from the multistage valve 50.
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In the Figs. 7 to 9 yet a further example embodiment of
the multistage valve in accordance with the invention is
illustrated.
Referring now to Fig. 7 there is illustrated the
multistage valve 80 again arranged in a valve port 81 of
an aircraft fuselage. The multistage valve 80 comprises a
first valve stage 100, a second valve stage 110 as well
as a drive mechanism 90. The first valve stage 100 and
the second valve stage 110 are arranged in sequence in
the valve port 81. Unlike the situation of the
embodiments as shown in Figs. 1 to 6 it is here the
second valve stage 110 and then the first valve stage 100
that receives the air flow in the direction of the arrow
L.
The multistage valve 80 is configured roughly rectangular
and provided with a frame 83. This frame surrounds the
valve port 81 on three sides. At the fourth side at which
the first valve stage 100 is arranged the frame is
provided with a curved portion 84.
The drive mechanism 90 comprises three links 91, 92, 93
connected to each other via pivots 94. The links 92 and
93 serving to actuate the valve stages 100, 110 are
connected to the link 91 on a common spindle. Pivoting
the valve stages 100, 110 is likewise achieved via pivots
94.
The first valve stage 100 comprises a bracket 101
pivotable about a spindle 102. The bracket 101 is rigidly
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connected to two sections 103, 104 forming roughly a
quarter of a cylinder. In this arrangement the section
103 is adapted to the curvature at the portion 84 of the
frame and is thus able to slide thereon. The section 104
comprises roughly the shape of a quarter-circle.
The second valve stage 110 comprises a fastener section
111 supporting the pivot 94 for attaching the link 93 and
which is pivotable about the spindle 112. To facilitate
pivoting, the second valve stage 110 is rounded at the
side facing the frame 83. The second valve stage 110
comprises furthermore at the side facing the first valve
stage 100 a, for instance, lip-type section 113, it
becoming thicker from this section 113 to a further
roughly plate-shaped section 114.
The functioning of the multistage valve 80 will now be
detailled with reference to the Figs. 7 to 9.
Referring now to Fig. 7 there is illustrated the
multistage valve 80 in the closed position. Both valve
stages 100, 110 are in their fully closed setting. In
this arrangement the two valve stages 100, 110 are
oriented substantially in a single plane and thus in the
same position. To prevent exhaust of the air mass flow
existing in the interior of the cabin of the aircraft
from the multistage valve 80 the roughly quarter-circle
shaped section 104 of the first valve stage 100 is firmly
urged against the lip-type section 113 of the second
valve stage 110. In addition sealing elements (not shown)
may also be provided.
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To open the multistage valve 80 the link 91 is pivoted in
the direction of the arrow D. This results in the first
valve stage 100 being slightly opened as shown by the
situation in Fig. 8. This valve setting is selected when
the aircraft is cruising, i.e. when a high differential
pressure predominates between the cabin interior and the
outer environment of the aircraft. The first valve stage
100 is open so far that not only control of the exhaust
air mass flow is assured but also at the same time a
maximum boost in thrust is achieved by the exhaust air
mass flow. In this arrangement the exhaust air mass flow
flows through an aperture 105 formed between the section
104 of the first valve stage 100 and the second valve
stage 110. The second valve stage 110 continues to be
closed sufficiently so that no air mass flow can exhaust.
Channellizing the exhaust air mass flow is done by the
section 113 of the second valve stage 110, the section
104 of the first valve stage 100 as well as by the frame
83.
Referring now to Fig. 9 there is illustrated the
multistage valve 80 in its fully open setting achieved by
pivoting the link 91 further in the direction of the
arrow D. This open setting of the multistage valve 80 is
selected when only a low differential pressure
predominates between the cabin interior and the outer
environment of the aircraft as is the case, for example,
in low-altitude flight or on the ground.
CA 02284819 1999-09-22
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In the fully open condition the first valve stage 100 is
remote from the valve port 81. In this arrangement the
section 104 is configured so that it completes the frame
83 in this fully open condition to thus achieve good
channellization of the exhaust air mass flow. In the
fully open condition the second valve stage 110 is
arranged substantially parallel to the valve port 81, it
thus presenting a very small resistance to the exhaust
air mass flow whilst maximizing the valve port 81 at the
same time.
In the embodiment of the multistage valve 80 as shown in
Figs. 7 to 9 air incident flow in the direction of the
arrow L is such that first the second valve stage 110
receives the incident flow and then the first valve stage
100. This arrangement of the valve stages 100, 110
reduces the torque needed to actuate the multistage valve
80 as will now be explained with reference to Fig. 8.
Referring now to Fig. 8 there is illustrated the
multistage valve 80 with the first valve stage 100 open.
The opening 105 permits an air mass flow exit. This air
mass flow mixes with the ambient air flowing by in the
direction of the arrow L, thus resulting in a swirl which
due to the differences in pressure materializing in the
swirling actions produces forces occurring downstream of
the multistage valve in the direction of the arrow L and
thus do not act on the second valve stage 110 but
directly on the fuselage of the aircraft. The second
valve stage 110 is thus influenced substantially only by
the differential pressure between the cabin and the
CA 02284819 1999-09-22
-24-
ambient air but not by the swirling actions. It is thus
able to be brought into its fully open setting as shown
in Fig. 9 with less torque than in the embodiment as
shown in Figs. 4 to 6.
Common to all embodiments of the invention is that the
multistage valve may be arranged in a single valve port
of the aircraft and that the smaller first valve stage
may be actuated separate from the larger second valve
section via a single drive mechanism thus achieving
maximum boost in thrust by the exhaust air mass flow in
saving energy. For an adequate seal, sealing elements may
be provided between the ends of the valve stages and each
valve aperture as well as between the intercommunicating
portions of the valve stages themselves. To simplify the
illustration these sealing elements are shown only in
part in the Figs.
