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14, 1947.
A, B, JEPSON ETAL
2,414,202
SUPERCHARGER AND EXHAUST VALVE‘ vCONTROL MEANS FOR PRESSURIZED CABINS
Filed July 4, 1942
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Fatenteti 5. in, test
2,414,202
SUPERCHARGER AND EXHAUST VALVE
CON'E‘RQL MEANS FOR PRESSURIZED
CABINS‘?
Alfred B. Jensen and James B. Cooper, Seattle,
Wash, assignors to Boei ng Aircraft Company,
Seattle, Wash, a corpor ation of Washington
Application July 4, 1942, Serial No. 449,742
l
6 Claims. (Cl. 98-1.5)
The maintenance ofpressure within aircraft
cabins or like enclosures at high altitudes, at
values to support life and reasonable activity
without at the same time overstressing the neces
sarily light structure, has received much thought
recently. The support of life and reasonable ac
tivity in such a pressure cabin requires not merely
maintenance of pressure at a suitable value with
in the cabin, but also a continual admission
of fresh air and withdrawal of vitiated air. There
must be, in other words, adequate ventilation,
which implies a ?ow-through, yet the pressure
must nevertheless be maintained at‘ a. suitable
under the in?uence of a cabin pressure factor,
in this application out?ow is controlled in ac
cordance with flow conditions. In any case,
however, each re?ects on the other, and the cabin
pressure is the ultimate control factor, and serves
to maintain pressure within the cabin elevated
above the external pressure, at least from cer
tain low altitudes upward, in some de?nite rela
tionship. In addition there is also provided, pref.
erably, a control coordinated with and affecting
the other controls in such a way as to be capable
value, elevated above external atmospheric pres
always of overriding the normal controls. This
overriding control would be, ordinarily. a di?er
titudes above take-off altitude.
pable of effecting such change in cabin pressure
sure at most altitudes. Indeed it may be some 15 ential-pressure control, though it might be of a
di?erent nature. It is such a, control as is ca—
what elevated above external pressure atall al- '
" To achieve ventilation, and to maintain pres
sure. without so rapid a rate of ?ow-through as
as will prevent the cabin pressure at any time
from exceeding the external pressure by a value
which bears some de?nite relationship to external
to be drafty and harmful, and to be wasteful of 20 pressure.
The normally operative pressure control, which
proper balance between in?ow and out?ow. This
may be referred to as the absolute pressure con
has been accomplished in part in Price Patent
trol, may in the present instance, control the ef
No. 2,208,554 :by regulating in?ow in accordance
with ?ow conditions, or rate of ?ow, and by reg 25 fective speed of a supercharger, and thereby its
rate of ‘delivery, re?ected in the rate of in?ow
ulating out?ow in accordance with some cabin
to the cabin. The overriding di?erential pressure
pressure factor, balancing the one against the
control may a?ect the out?ow valve to cause its
other. In the Price patent both such controls
greater opening upon any tendency to exceed the
were valves, and since the inlet valve was ar
ranged to'holcl back such ?ow as might other 30 selected di?erential, or it may act upon the in?ow
control to prevent such speed of the supercharger
wise have been obtained from the supercharger
being attained as will, at the corresponding rate
which was of constant speed or connected to a
of out?ow, produce a pressure in the cabin in
propelling engine to be of substantially constant
‘excess of the selected differential.
speed, power was used unnecessarily, in order
With these exceptions and differences the pres
that the supercharger might have ‘adequate ca. 35
ent system resembles’ the system of the Jepson
pacity when the requirements were the greatest.
and Cooper application, Serial No. 415,603 and to
This clii'?culty was solved by the system of the co
a large degree the principles of the present ar
pending application of Alfred B. Jepson and
rangement may be varied in its application in
James B. Cooper, Serial No. 415,603, ?led Oct.
18, 1941, by employing a supercharger variable 40 di?erent ways, as may be done in that applica
tion, and to accomplish various related but spe
in speed in accordance with ?ow conditions, and
ci?cally diiferent ends.
‘
'
by employing as in the Price system, an out?ow
The
accompanying
drawing
shows
the
present
controlling valve variable in accordance with a
system in diagrammatic form, it being understood
cabin pressure factor. '
;
'
that the details of the structure, sustaining wings,
It is also possible, and in some cases it may be
propulsive engines, and the like are either omitted
preferable, to. in e?‘ect, reverse the control fac
or shown only in diagrammatic fashion, and
tors in their relationship to in?ow and out?ow.
purely for the purposes of illustrating the prin
and arrangements to that end are disclosed in
ciples of the present invention.
this application. For example, whereas in the
The ?gure is a, diagrammatic 'view, with parts
Jepson and Cooper application, S_erial No. 415,603,
in section, illustrating a, cabin, and the inlet and
the rate of in?ow was variable in accordance with
outflow controls therefor, and the automatic con
?ow conditions, in the presentapplication the
trols for maintenance of proper cabin pressure
in?ow is controlled in rate in accordance with a. ,
under all conditions.
cabin pressure factor, and whereas in the Jep
The sealed cabin is diagrammatically repre- '
son and Cooper application out?ow was controlled
power, there must be maintained a delicate and
55 sented ‘at 9, and has an in?ow port Stand an
'
2,414,202
a
.
.
out?ow
port 92, the latter leading to the atmos
phere. This cabin is part of an airplane capable
of rising to high altitudes, ior instance 20,000
to 40,000 feet, under the power of propulsive en
gines, diagrammatically represented at 90.
'Air under pressure is supplied to the interior
of the cabin 9 by such means ‘as a supercharger
4., receiving air through an inlet i0 and deliver
The latter is controlled, under the in?uence
of ?ow, by a plus pressure duct BI and a negative
pressure duct 32, the latter connected to the sub
venturi 2|, which ducts ti and 32 are connected
to the opposite sides of a plunger 8 carrying a
stem 33, biased to move toward and to close the
entrance, to the hollow stem 22 by a spring 34.
At normal flow rates the end of the stem 33 is
_ maintained in equilibrium, spaced a few- thou- *
ing it through a‘ conduit II to the cabin in?ow
sandths of an inch from the end of the hollow
port 9!. The supercharger I may be driven in 10 stem 22, and thereby the latter is maintained in
various ways, being shown as connected to one
turn in a position of equilibrium. It the ?ow rate .
increases, the stem 83 is lowered, the pressure
above the servo piston 23 is increased more rap
which is variable in accordance with the amount 0 . idly than it can be bled away past the piston,
oi ?uid retained within its casing, thence 15 by reason of greater access through the'hollow
through gearing‘within a gear box l8. The
stem 22, and the valve-2 tends to follow the stem
amount of ?uid acting upon the ?uid drive i2
33 downwardly, restoring parts to equilibrium in ‘
is variable, as will be later explained in detail,
a now more greatlyv closed position of. the out- p
hence the speed of the supercharger I with re
20 flow valve 2.‘ If the ?ow rate tends to decrease,
of the propelling engines 90 through a ?uid
drive l2, the e?ective power transmission of
lation to its driving engine 90 is variable, prefer
parts move in the opposite direction into a new
.ably automatically in accordance with a cabin
pressure factor, as will be made clear hereafter.
It will now be clear that the valve ‘2, being
position of equilibrium, and thus the ?ow rate is
always moderate, and substantially constant,
spring 34 being light so that the change in ?ow
?ow-controlled, may be regulated to maintain
under equilibrium conditions for various posi- constant‘ ?ow at the desired rate, by proper con 25 tions of stem 33 is negligible.‘
striction or the out?ow port 92. If the super
The speed of the supercharger I, it will be
charger’s speed were only su?icient to replace
the air thus discharged, the cabin pressurewould
remembered, and’ hence supply of adequate
amounts of air at suitable pressure to the cabin,
nit rise, but since the supercharger can be
is under control or the amount of fluid within
the
arrangement
shown
its
30
speeded up, and in
the ?uid drive unit i2. Less ?uid within this
speed increases automatically with decrease of
unit i2 slows down the speed of the supercharger;
cabin pressure, this increase of supercharger
more ?uid within the ?uid drive unit speeds up
speed results in an increase of cabin pressure.
the supercharger, assuming a constant speed for
Thus, while the present arrangement is the re
the propelling engine 90. Accordingly a control
verse of that in Serial No. I£15,603 in the‘ sense 35 valve 6 is connected in the ?uid line l5, between
that now the in?ow is pressure-controlled in
stead of ?ow-controlled, and the out?ow is ?ow
controlled instead of pressure-controlled, never
theless the two are comparable in the sense
that, in both instances the cabin pressure is regu
lated by varying the speed of the supercharger.
‘
the pump is drawing from a reservoir l1 and
. the ?uid drive unit 62, and automatic means are
provided for the regulation of the position oi the ,
46
control valve 6 inaccordance with one- or more
pressure factors related to the pressure within
the cabin.
,
To these ends we provide an out?ow valve 2,
As typiiying a means to this end, there has
movable towards and from its seat, 20 to regu
been shown a servo piston 80, connected to oper
late out?ow past a venturi 93 leading to the
ate the valve, and itself under immediate control
45
out?ow port 02. Such position of the out?ow
of a pilot valve ii i, the piston 40 and its pilot valve
valve 2' is under automatic control of ?ow-sensi- _ 8i being connected to the shiitable diaphragm
tive means, and these ?ow-sensitive means may
54 of an absolute pressure unit, generally repre
be disposed to be sensitive to the flow through
sented at“ 5. This‘pressure unit, as shown, con
the venturi 93, as by the sub-venturi 2| shown,
sists of an evacuated bellows 5i, .and a bellows
or to ?ow from the cabin towards the valve 2, 50 '52 communicating ‘by way of the duct 50 with
or to flow through the conduit ii into the cabin.
the interior of the cabin, with the diaphragm 54
The e?ect is substantially the‘same, for it is the
connected between the bellows 5i and 62. A
. ?ow through the cabin which governs the posi
head 53, which may be considered as a ?xed head,
tion of the pressure-controlling valve 2.
~
closes the outer end of the bellows E2, and a simi
55
This valve is in man _ respects similar to the
lar head 55, fixed with relation to the head 53,
in?ow valve of the Price patent referred to above.
closes the outer end of the evacuated bellows 5!.
A tension spring 58, adjustable by means such
and from its seat to regulate ?ow, having a
asthe screw 56, urges the diaphragm 54 towards
hollow stem 22 open to cabin pressure at its
the head 53, but this force is resisted by the
lower end, and opening at its upper end into'the 60 e?ect of the pressure within the cabin acting,
space above a piston 23 (or diaphragm) of
within the bellows 52, upon diaphragm 54 in
larger size than the valve. The servo‘ piston 23
opposition to the spring 58. A true balance be
is arranged for bleeding of pressure, or for ?ow
tween such cabin pressure and the spring is thus
or controlled leakage, from its upper or high
obtained because the evacuated bellows 5| be
65
pressure side to'its lower or low pressure side.
tween the opposite side of the diaphragm 5i and
The low pressure side of the piston is connected
the head 55 eliminates the effect of any other
by the duct 24 to atmosphere, which is under
force on such diaphragm. These two forces are
It is shown as a conical valve, movable towards
almost all conditions at aglower pressure than
thus brought into equilibrium at ‘some particular
that within the cabin. The result is that the
setting of the diaphragm'td.
servo piston, acting against valve forces, created 70 in any such position of equilibrium the pilot
by differential pressures and out?ow acting on
valve 4! is closed, but upon disturbance of their
the valve, serves to close the valve 2, but the
equilibrium the pilot valve 4| opens in one direc
amount of closing and its positionis determined
tion or the other, thereby e?ecting' corresponding
by the amount of opening through the hollow
movement of the servo piston B0, and in conse
' stem 22‘.
2,414,202
quence corrective movement of the connected
valve 6, and adjustment correspondingly of the
speed or the supercharger. For instance, if the
for which thespring 62 of. diil'erential pressure
control 6 hasbeen set. .
The absolute pressure control 5 and the dif
cabin pressure tends to increase more than‘is
proper, the diaphragm 56 will be moved to the 5 ferential pressure control 6 may be part of a com
mon unit, within the enclosure 99 represented
right by it against the tension of spring 58, as
in phantom, and this unit may be located. within
will the pilot valve ti; the servo piston 1w will
the cabin, adjacent the engine 90, or in any other
then be moved to the left by a pressure ?uid en-_
convenient position.
tering at or, and this will shift the control valve
‘What we claim as our invention is:
4 in a direction to close itfarth'enthereby re
1. Aircraft cabin pressure control mechanism,
, ducing the amount of ?uid e?ective within‘the
comprising means to supply air under pressure to
?uid drive unit it and thereby slowing down the
the cabin, an outlet for out?ow of air from the
supercharger l. Follow-up movement of the pis
cabin, valve means controlling out?ow of air from.
ton will restore the pilot valve ti to neutral po
sition, through the linkage shown, and parts will 15 the cabin through said outlet, means sensitive to
out?ow of air from the cabin through said outlet
then remain in the new position of equilibrium.
and operatively connected to control movement of
Should the cabin pressure drop, the reverse ac
tion will take place, and the supercharger ‘will , said valve means to regulate out?ow of air from
speed up.
~
the cabin past said out?ow sensitive means and
Were the structure of the cabin e sufiiciently 20 said valve means, tending to maintain a constant
rate of air out?ow through said outlet, and pres
strong and air-tight under all conditions of pres
sure-sensitive means exposed to cabin pressure
sure di?‘erence, as between the cabin and the
and operatively connected to said air supply
exterior, the absolute pressure control 5 might
means to regulate the supply of air to the cabin
be adequate under all conditions, but this is
.
scarcely practicable. Usually the cabin struc 25 for controlling the cabin pressure.
2.
Aircraft
cabin
pressure
control
mechanism,
ture is designed to hold a maximum differential
comprising means to supply air under pressure
of pressure, and it is desirable to provide over
to the cabin, an outlet for out?ow of air from
riding and automatically operable means to pre
the cabin, valve means controlling out?ow of air
vent the pressure in the cabin eve/r exceeding
that di?'erential over external pressure‘. _To that 30 from the cabin through said outlet, means sensi
tive to out?ow of ainfrom the cabin through said
end there is provided the differential pressure
outlet at the discharge side of said valve means
control" eans, generally represented at 8.
and insensitive to cabin pressure, operatively con
This éE‘ilerential pressure control, as shown in
nected to control movement of said valve means
the dra ing, consists of a stem 65 connected to
shift the absolute pressure control device 5 as a 35 to regulate out?ow of air from the cabin“ past
said out?ow sensitive means and said valve
unit. It is connected, for instance, to the head
means, tending to maintain a constant rate of air ‘
5%, which in turn is connected to the opposite
out?ow through said outlet, ‘and pressure-sensi
head 55 by the bellows St , to move the unit along .
tive means exposed to cabin pressure and opera
the guides El, and when such movement is made,
corresponding adjustment is accomplished of the 40 tively connected to said air supply means to reg
ulate the supply of air to the cabin for control
pilot valve 4! with the same results as before.
The stem 65 is shouldered at be for engage- - ling the cabin pressure.
3. Aircraft cabin pressure control mechanism,
ment by a pressure sensitive member or piston
comprising an inlet duct communicating with the
6|, when moved in opposition to force means,
represented by a spring 62, engaging such portion. 45 cabin, means to supply air under pressure to the
cabin through said inlet duct, an outlet duct for
The pressure sensitive member or piston is thus
?ow of air from the cabin, valve means control
moved by cabin pressure supplied through the
ling out?ow of air from the cabin through said
conduit as acting against its left surface, as op- '
_ outlet duct, means sensitive to ?ow of air through
posed by atmospheric pressure communicated to
the opposite side of the piston at through the 50 one of said ducts and operable to regulate said
valve means for controlling the out?ow of air
duct be acting on its right surface of substan
through said outlet duct, means sensitive to ab
tially equal area, and by the'force exerted by
solute cabin pressure and operatively, connected
spring or. When atmospheric pressure and cabin
to said air supply means to regulate. the supply
pressure are not widely different the spring 62 will
hold the piston ti away from the shoulder 60. 55 of air to the cabin tending to maintain a sub
stantially constant cabin pressure, and means
At a given value, for which the spring 52 is set
sensitive to the difference of cabin pressure over
to exert on piston 6i a substantially uniform force
corresponding to a predetermined differential of
atmospheric pressure, also operatively connected
to said air supply means, and always operable to
cabin pressure over external pressure at various
override
said absolute-pressure sensitive means
altitudes, and for which it can be adjusted to 60
to limit the supply of air to the cabin to prevent
select different desired given values by means not
the differential of cabin pressure over atmos
shown but known and readily applicable, the pis
pheric
pressure exceeding a predetermined value.
ton engages the shoulder M and commences to
4. Aircraft cabin pressure control mechanism,
move the stem 65 to the right. In so doing, as
comprising an inlet duct communicating with
has already been described, the servo piston Ml
the
cabin, means to supply air under pressure to
is caused to move in a direction to increase the
the cabin through said inlet duct, an outlet duct
choking oi’ the passage through the control valve
[for ?ow of air from the cabin, means exposed to
thereby slowing down the supercharger i and
cabin pressure and operatively connected to said
decreasing the pressure within the cabin l. Since
this action occurs only when the external pres» 70 air supply means to regulate the supply of air
to the cabin to establish and maintain a cabin
sure has dropped, and if by this action the cabin
pressure
higher than atmospheric pressure,
pressure drops correspondingly, it follows that
means operable under the in?uence of air iiow
the cabin pressure is never permitted to exceed
through one of said ducts to vary the rate of air
the external pressure by more than ‘the prede
termined diiierential corresponding to the value 75 out?ow from the cabin through said outlet duct,
to maintain a predetermined air out?ow rate“
aaieaoe
and overriding means operatively connected to
said air supply means, and sensitive to the presc
sure differential of cabin pressure over atmos
pheric pressure, always operable upon the attain
ment of a, selected differential of cabin pressure
over atmospheric pressure to actuate said air sup
ply means to prevent cabin pressure exceeding
atmospheric pressure by more than such selected
pressure differential.
5. Aircraft cabin pressure control mechanism,
comprising an inlet duct communicating with the
cabin, means to supply air under pressure to the
cabin through said inlet duct, an outlet duct for
flow of air from the cabin, means exposed to cabin
' ceeding atmospheric pressure by more than such
selected pressure di?erential.
6. Aircraft cabin pressure control mechanism,
comprising an inlet duct communicating with
the cabin, means to supply air under pressure to
the cabin through said inlet duct, an outlet duct
- for outflow oi’ air from the cabin, valve means
controlling out?ow of air from the cabin through
said outlet duct, means sensitive to flow of air
through one of said ducts“ and operable to regulate
said valve means for controlling the out?ow of air
through said outlet duct, and differential pressure
control means including force means operable to
exert a substantially uniform force corresponding
to a predetermined differential of cabin pressure
pressure and operatively connected to said air 15 over external pressure at various altitudes, andv
supply means to regulate the supply of air to the
cabin conformabiy to the rate of air out?ow to
maintain the cabin pressure substantially con
» stant, means operable under the in?uence of air
a pressure sensitive member engaged by said force
means, having surfaces of substantially equal
area exposed to cabin pressure and to atmos
pheric pressure, movable by the di?erence in such
?ow through one of said ducts to vary the rate 20 pressures on such surfaces opposed solely by the ,
of air out?ow from the cabin through said outlet
force exerted on said pressure sensitive member
duct, to maintain a predetermined air out?ow
rate, and overriding means operatively connected
by said force means, and operatively connected to
said vair supply means to limit the supply of air
to said air supply means, and sensitive to the
supplied thereby to the cabin, to ‘prevent the dif
25
pressure differential of cabin pressure over at
ierential of cabin pressure over atmospheric pres-i
mospheric pressure, always operable upon the at
sure exceeding a predetermined value.
1'
ALFRED B. JEPSON.
tainment of a selected differential of cabin pres
sure over atmospheric pressure to actuate said
JAMES B. COOPER.
air supply means to prevent cabin pressure ens
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