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Nov. 5, 1946.
w. s. POWELL _
,
.
2,410,522
_
' INLET VALVE FOR lGAS COMPRESSORS
Filed June 17, 1942
BY'Y @vanaf-M
l
w
`
Patented Nov. 5, 1946
ZAlÜßZZ
UNITED STATES plilxTtEN'l‘vv` OFFICE
rNLE'r VALVE Foe Gas oor/.transenne ì _ ~ ` 9
I William" S. Powell, Indianapolis, Ind., assignor to
Marmon-Herrington Company, inc.,A Indian-~
apolis, ind., a corporation of-Indiana.
Application J une 17, 1942, Serial No. 447,47€! _'
3 Claims.
(Cl. 230-2)
I 2
`In the operation of modern airplanes,r main
of av barome'trically‘ sensitive cell l ‘lí in" such man-`
tenance of a supply of compressed air is an essen
, ner thatth'epas'sage between seatl lë‘and" valve-
tial, While, at the same time, conservation oi
it“ will varyf'inversely' with variations of baroìpower requisite for such maintenance is desirable.
metric" pressure so that the successive masses“ of
Heretofore, it has been customary t'o` provide 6 air which may enter the compressor during suc~v
a compressor and a motor, generally electric, so
cessíve-s‘uction strokes, atrnormalspe'ed-o‘f opera
proportioned that the motor is capable of aotuat~
tioifiîo'f'th'eicompressor, willi be uniform,.i. e., lessi
ing the compressor at full capacity at ground level «
volume-‘of admitted air’> at atmospheric pressure~>
to deliver compressed air to the desired maximum
at 16W altitudes thanv at high( altitudes.
pressure and in such an arrangement, at higher 10
As the mass of air in a" given >volume varies in“-->
levels due to the lower pressureoic air supply,
the maximum power of the motor is much greater
versely with‘it‘s temperature, it may also be de
than is required. ì
cordan'ceï with variations init'einper'aturë of theV
sirable' to control the- position of- valve Iliin ac~
rEhe object ofVY my invention is to provide an`
improved method and means by'whiohthe quan 15
tity of air which may be-supplied-toa compressor
on its suction stroke, at its normal rate of speed,
will be varied in- accordance with the barometric
pressure of the air supply and, as av supplement,
inaccordance with the temperature of the air 20
supply, so that the massgof compressed air dis
charged at each stroke (unit operation) of the
compressor will be- substantially uniform irrespec»
tive of the altitude of the apparatus and tern
perature of the air supply.
air supply', valve’ i6 being' near'erto` its seat,` at'.
a given barometri‘cl prëssur'e’,.when the air supply
isV cold' than when" the" airis at a higher’te'mpera
ture.
‘
For that purpose, cell if'l’may be supported upon
a thermally responsive support’ so that it’sîeiîectv
on valve' I‘B will- vary with the' temperature on
the surrounding air supply, or a thermally-re
sponsive'element’ may be installed as _a part of
the connection between cell Il andvalve I5 to
attain the desired end. It seems probable that a
'
25 valve of the needle type, as shown in Fig. 5, wiltl
The accompanying drawing illustrates my in
vention.
be' most convenient, though I wishY itrunderstood
thatjmy invention is not limited’to suchY form.>
The proper' contour of valve I'ôvmay be readily»
Fig. v1 is a> diagrammatic illustration of` an em
bodiment ofV my invention;
determined mathematically' so that for all posi'- '
Fig. 2' an axial section of an appropriate coin- v 30 tions-of the valve relative to` its seat under cur“
presser inlet valve and- associate barometrically
sensitive controller;
"
‘
I
Fig. 3Y an axial section of another
trolled inlet valve;
,
v
~
formof con# y
.
.
-
Figwi a fragmentary section showing a- ther
mally-responsive "addition to> the structure' of
Fig. 2;
Fig. 5a secti‘onronv an enlarged scale, of an.
appropriate needle -valve and associate seat; and
rent conditionsof supplyV pressure- (and tempera'f
ture if_ desired) itr will permit only a flow of‘a`
predetermined, _mass of air' per unit of time into;A
the compressor.
Uniform.massesof` airmaybe compressed to
a. predetermined pressure- by the> expenditure...ci`
uniformv quantities. of power. Consequently, the.
motor.H il at low altitudes'will be’called uponfor '
the same amount of work as at higher altitudes'
Fig. 6 a section, on a smaller scale, of a niotiii 40 and thereby maximum eñiciency 0i» the apparatus
_F1-ed form.
'
y
v
ln the drawing, laindicates'an air-compressor
or any desired form' driven by a motor I`I and
provided with a discharge duct I2 leading to ay
storage chamber I3; and an ’inlet duct I4 openA to
atmosphere.
1
'
-
rllhe motor i I need only'be- powerful enough to
obtained because va small motor capable at its
maximum >capacity of. producing desiredl com
pression of air obtained at ahigh altitude will
still’be capable of effectively operating, thecorn
pressor‘a't low altitudes.
,
p Referring» to Figs, 2 and 5; the valve It 'com
prises a circumferential flange 2li which may'seatv
eiîectively -drive vthe compressor at thev highest f
on the annular seat I5, and a tapered plug'po'r--
contemplated altitude and, therefore, much too
tion 2| the various diameters ; of which are so
small to effectively drive‘the compressor at- full 50 proportioned as tofvariably block theeye of seat
capacity when at- ground‘ 1evel.,- Therefore, in
I5 as the valve is axially shi-ftedinaccordance
order to render such a- motor effective at ground
with altitude variations.
level,I part of the inlet'du'ct lffl'comprisesa-valve
seat I5 and cooperating valve-> It;- thef‘positionfci
which relative to seat- I5~is subiectfto’ther-control
Valve seat I5 is anchored in bore 22 of nipple
23 and valve I6 is biased toward seat I5 by a
spring 24.
-
.
2,410,522
4
3
Note: Comparative areas:
A 1/8 in. dia. hole has an area .0122 in.2
Attached to the inlet end oi nipple 23 is a cup
25 within which is the barometrically-sensitive
cell I1.
.
In order that cell Il may respond in suñîcient
amplitude to variations of pressure of the sur 5
rounding atmosphere, it is composed of two cups
_21, 21, sealed together, mouth to mouth, at their
perimeters and axially slidable' in a foraminous
.000576: .00057 6X 19.5: .01122: .00756 sq.
.53x28
1.485
1.485
in.
Tes-o
_
A §35" dia. hole has an area .0069 in.2 .
.00756 sq. in.=area of the orifice to pass .000576
shell 28 which, at its perimeter,- is formed to fit»
lb. of air/sec.
’
cup 25 and, at the same time, aiîord air passages 10
Y» Check:
to valve seat l5, as indicated by arrows. Shell
It” the pressure is 14.7 lb. 1 in.2 and the tempera
28 is held in place by a retainer ring 28'.
ture is 0, one ft.3 of air will weigh .08635 lb.
One cup 21 of the barometric cell, at its center,
`An opening .00756 in.2 will pass
n is anchored to shell 28 while the other cup „21,
at its center, is provided with a pocket 29 into 15
which the adjacent end of valve i6 seats» As the
pressure of the air surrounding cell Il decreases,
the cell bulges at its center and this so positions
valve I6 relative to its seat I5 in accordance withY
.00402 X .685
the altitude of the device that uniform masses 20
of air Vare admitted vto the` compressor at what-v
.003742 lb. of air per sec. (6l/2 times too much).
ever maybe the altitude of the apparatus.
,
Therefore the opening will have to close to
The proper contour of valve IB, taking account
.00402Xä5
only of barometric pressures, may be determined t
as follows:
. -
1
If the total amount of movement of valve IE
is designated by the letter M thenthe requisite
movement of the valve for proper altitude posi
tion will be proportionate parts of M as shown in
Fig. 5 and outlined below.
,
late the air inthe proper amount.
_
Actual values of D and M vary with the capacity
of any device upon which the valve is used. The
properrelationship, when the compressor oper
ates to attain a maximum pressure of 1000 pounds,
may be determined in the following manner:
.
t
'
Valve
Diameter of
motion
valve at M
(M)
(alt.)
0
0. 966D
.
m><~00756=1538=~00116 111.2 at 125° F.
An opening .00116 in.2 willpass
_.000615àî-'ÃX1507 :.000374 lb. ofl air/sec. at 125° F.
30'."
t
If the diameter of the total opening is desig
nated by the letter D then the diameter of the
valve at various altitudes must be made to match
the amount of motion of the plunger and regu
Altitude (feet)
.000575
25E
.
In order to compensate for temperature varia
tions, a 'ni-metallic temperature responsive cush
, ion 30 (Fig. 4) may be interposed between valve
l0 and pocket 29, expansion or contraction of this
_ _cushion by reason of temperature of the sur
3": -` rounding air serving to lengthen or shorten the
connection between cell I1 and valve i6.
Cup 25 may be provided at its mouth with
screens 3l and filter 32 held in place by ring 33.
Referring to Fig. 3, 40 indicates the main body
>of an inlet valve structure having an entry pas
sage 4| provided with a valve seat 42. Cooperat
ing with seat 42 is a. valve 43 anchored on one
wall 44 of a barometrically sensitive cell I1', the
opposite wall of which is provided with ears 45
45 pivoted at 46 to one end of a stem 41 projected
through an arch 48'of body 4l] between nuts 49
and 50.
Leading into passage 4l, on the discharge side
. 044
. 084
. 965D
. 963D
. 128
. 961D
. 168
. 208
. 384
. 960D
. 959D
. 951D
. 532
. 659
. 940D
. 926D
. 771
'. 908D
In use, stem 4l' may be so adjusted that, at
. 860
'.891D
. 930V
. 854D
ground level, valve 43 is spaced «from seat 42 to
l. 000
Y, of Valve 43, is an inlet passage 52 controlled by a ,
50 needle-valve 53.
aiîord entry of the'proper mass of air to permit
809D
motor H to function.
The variables involved in the calculations can 551:
all be simpliñed by utilizing the weight of the air
to be‘handled rather than theïvolume, because
themass varies continually with the altitude and
the
temperature.
-
‘
.
1 cubic foot of air at 40,000 ft. weighs
‘
-
'
As the altitude of the structure rises, cell l'l
will bulge so as to move valve 43 away from seat
42 to admit additional volumes of air, at lower
pressure due to altitude, so that the air flow
through the structure in a unit of time, will be a
60 predetermined mass within the capacity of the
compressor motor.
'
It will be noted that with the described arrange
ment, the masses of air which may enter the
Assuming the compressor speed to be 4000
R. P. M. andthe displacement to be 3000 in.3 or
1.736 cu. ft./min., the inlet oriñce >must admit at
allv times l.736><.0199=.0346 lb; per min., .000576
lb./sec'.V
`
i
`
Fliegner’s equation‘for oriñces (Trans. A. S.
Mnxxvneiee) i’sÍ'W=f.53AçP/\/T>,. Weight:
.000576 as above, ysolving forï `
'
A nl
_.5313 '
'
N compressor for -successive charges will be uniform
>’irrespective of variations of atmospheric pres
' sure.
Therefore, this desired mass having been
determined, an energizing motor for the compres
sor'may' be’selected which, at its delivery speed;
will operate at its highest efñciency at all times.
70 Such an arrangement therefore reduces to a min
imum, weight and size of the unit.
'
In order to minimize temperature effects, a
construction'like that shown in Fig. 6 may be
used. In this form an evacuated “sylfon” cell
21' has suñicient expansive axial resilience, when
5
2,410,522
external pressure is reduced, to move valve 2|
from its seat. This cell is sup-ported in the main
body 25 by the foraminous shell 282, as in the
construction shown in Fig. 2. Because of the re
duced air content of cell 21’ variations of tem
perature of the surroundings of the cell have little
6
barometrically-sensitive, evacuated, inherently
expansive cell associated with said elements so
as to control their relative position in accordance
with the pressure of air admissible between said
two elements, and including a thermally-respon
sive element interposed between said cell and one
of said pair of elements.
3. The combination with an air 4compressor and
1. An inlet valve structure for air compressors,
an
actuator of insuflicient power to drive the same
comprising a pair of elements relatively shiftable 10 at full
capacity at ground level, of a valve con
to control passage of air therebetween and a
trolling the inlet of said compressor, and a bar
barometrically-sensitive unit associated with said
eiîect on the pressure Within the cell.
I claim as my invention:
ometrically-sensitive, evacuated, and inherently
elements so as to control their relative position
expansive cell within the influence of the air
in accordance with the pressure of air admissible
supply for said compressor and connected to said
between said two elements, and including a ther 15 inlet valve to control its effective position relative
many-responsive element interposed between the
to the compressor inlet, whereby substantially
barometrically-sensitive unit and one of said
uniform masses of air will be drawn into the com
pairs of elements.
~
pressor upon unit operation of said compressor
2. An inlet valve structure for air compressors,
irrespective of the pressure of air supply due to
comprising a pair of elements relatively shiftable 20 altitude of the compressor.
to control passage of air therebetween and a
.
WILLIAM S. POWELL.
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