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Патент USA US2406181

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` F. J. WIEGAND.. `
Filed Jan. 14, 1943
FRA Nc/s d. W/:GA/vn.
/a a’ if’
Patented Àug. 20, 1946
2,406,181 `
` 2,406,181
. Francis J. Wiegand. Ridgewood, N. J., assignor to'
.Wright Aeronautical Corporation, a corporation
of New York
_ Í 1 Application January 14, 1943, seria1Nò.472,409
",_ " l
3 Claims.l
(C1. 121-41)
This invention relates to measuring apparatus
36 in the wall of chamber 20 and this opening
and is particularly concerned with apparatus for
forms a seat for the valve 30. The valve 30 there
transforming small pressure differentials into
by controls the transmission of pressure from
larger and more useful pressure differentials.
l chamber 20 to chamber 32. Accordingly, the dia
A typical'application of this invention is for
measuring small low rates of fluid iiow by means
of a venturi. Inaccordancewith this invention,
the small dili'erential pressure produced by a low
rate of iiuid flow through a venturi is transformed
into 'a larger pressure differential. Thus, the
apparatus could be used for measuring fuel flow
phragm 26 is subjected to a force to ¿the right,í
as .seen in the drawing, to balance the Vvforce ,act-¿
ing on diaphragm 274, the force acting on elia-`
phragm 26 being equal to the pressure differentialv
ï between the pressure in chamber 32 and atmos;
A small
flow inortheother
I0 will
subject the '
to an internal combustion engine. In the prior „
diaphragm 24 to a small force'to the left to open l
art, in order to transform a small pressure dif
the valve 30. Pressure will then be transmitted
from chamber 2!) to chamber 32 until the dia
phragm 26 is subjected tov a suii‘lcient pressureY
acting on diaphragm 24.~ Upon an increase in iiow
in conduit ‘,I0, the pressure differential on dia
phragm 24 increases to further open the valve _30
until the pressure differential acting on the dia-`
ferential into a larger pressure diiîerential, it is
common practice to do so by using electric er
pneumatic relays which control an external source
of energy. It is an object ofthis invention to
transform the small differential pressure to be
measured into a larger pressure differential with
out the use of any external Source of energy.
differential to balance the'pressure differential
Specifically, this invention comprises a dia
phragm 26'has increased suiiiciently to again bal
phragm system consisting of a relatively large
ance the system»- Similarly, a decrease in flow»
through the conduit I0 results in a decrease in
diaphragm subjected to a pressure diiferential re
sponsive to the condition to be measured and a
, the pressure differential acting on the diaphragm
second diaphragm mechanically connected to the 25 24v thereby moving the `valve 30 in a closing direc- »
ñrst diaphragm for movement therewith. The
tion. The bleed 34 inthe chamber 32 then per-.
mechanical connection between the diaphragms
mits a reduction in the pressure in this chamber>
operates a valve for controlling the transmission
until the pressure diiferential acting on `dia’- »
of pressure from the high pressure side of the
phragm ,26 has been reduced 'suiiiciently to again
larger diaphragm to the high pressure side of the 30 balance the diaphragm system.` Thus, the valve>
smaller diaphragm to balance- the diaphragm
3i|will assume a position to maintain the correct.v
pressure in the chamber 32 to balance 4the d-ia- .'
Other objects of thisinvention‘will become ap
parent in reading the annexed detailed descrip
When the diaphragm system is balanced, the
35 pressure differential acting on the‘smaller dia- .
tion in connection rwith the drawing, in which:
Fig. 1 isa diagrammatic view of the invention;
phragm 26 is necessarily largerthan the pressure -~
differential acting on the larger diaphragm »24
Fig. 2 is a diagrammatic view of a modification.
in proportion to-the ratio of the areas -of these
Referring to the drawing, a conduit I0 is pro
diaphragms. Therefore,V since the pressure dif
vided with a Venturi throat I2 for metering the 40 ferential acting on the diaphragm 24 is a measure
flow of the fluid through the conduit. Conduits
of the iiow through the conduit I 0,-the larger-y
I4 and I6 connect the Venturi throat I2 and bar
and more useful pressure differential acting on
rel I3 with chambers I8 and 20, respectively. ' the diaphragm. 26 is also av measure of the` flow
These chambers are formed within a housing 22
by a flexible diaphragm 24. Thus, the diaphragm
24 is urged to the left, as seen on the drawing, by
through4 conduit` I U. Accordingly, this larger pres.
' sure Vdifferential may be used to operate an indi
cator calibrated so as to indicate the flowincon- v.
a force proportional to the magnitude of. the flow
duit I0. -Y
through conduit I 0. A second diaphragm 26 'is
mechanically connected to the diaphragm .24 by
VVAt this_point 1tV shomd be noted that the reía
tive sizeof the diaphragms must be correctly pro- Y
portionedin View of thelmagnitude of the pres
a stem 28provided with av poppet valvef30. This
diaphragm 26 separates the chamber 32.from the
sure diiîerential acting on the diaphragm 24 and ,
atmosphere or other balance pressure and a re
strictive outlet 34 provides a drain bleed for the
chambertothe atmosphere or-_other vent pres
sure. The stem 28'pas`s'es througli'an'opening
in View of lthe relative magnitude of these pres-j
sures lasicompared 4to the atmospheric pressure .Y
Aor other balance pressure to which the diaphragm
is subjected. Thus, if the diaphragm'ZE is too
The apparatus has been illustrated and de
scribed in connection with the pressure differen
small or the pressure differential on the dia
phragm 24 Vis too large, it will be impossible to
develop sufficient pressure within the chamber
32 to balance the diaphragm system even though
valve 30 is fully open. Also, with atmospheric
tial created by a fluid iiowing through a venturi.
However, the apparatus is of general application f
and can be used wherever amplification of a small
pressure differential is desired.
pressure on one side of diaphragm 26 it i-s essen
tial that the pressures on both sides of diaphragm
While I have described my invention in detail
in its present4 preferred embodiment, it will be
obvious to'those'skilled in, theart,y after under
24 be greater than atmospheric pressure, other
Wise it Will be impossible to balance the dia-‘5
phragm system. However, if the right side of the
diaphragm 26 is subjected to other >than atmos-.l ,_
pheric pressure, it is only necessary that the pres-1l '
sures acting on diaphragm 24 be greater'tlfianA . ‘
standing my invention, that various changes and
modifications may be made therein Without de
parting from the spirit or scope thereof. I aim’
the appended claims to cover all rsuch modi
this other pressure. As previously stated, Ythis in_
íications and changes. '
vention may be used for measuring fuel flow toan
internal combustion engine. In such case, a fuel
pressure of 15 pounds per square inch is typical.
I'cl'aimas my invention:
' l'. vInV apparatusk for transforming apsmall pres
sure differential into a larger pressure differen
` k However, this pressure is only mentionedfby wayy ' '
of example. and is not to be construed as limiting
tial, the individualpressures of. said small pres
sure differential both being greater than atmos
the use of the invention.
pheric pressure, a housing, a ñrst movable mem-’
In Fig. l the amplified pressure differential
acting on the diaphragm 26 is used for operating
a remote Selsyn motor type indicator. The pres-v
sure from the chamber- 32 is transmitted vby a pipe
31 to a “Siylphon”>bellows38 so that this bellows
Vis subjected to the same pressure diii’erential pei-
wall ofthe high pressure chamber removedl fromV
ber dividing said housing into a pair of opposedv
chambers, means for subjecting said memberand»,
chambers to said small pressure differential, >theî
said member having an opening therethrough>
25. into
a third chamber, a second movable member
‘ unit-effective area as diaphragm 26. ‘The bellows
38 nis connected to thegvrotor of a Selsyn trans-_
mitter -40 bypa'rack 42 and a pinion 44.
The _
in said third chamber connectedjto> said Víirst'>
member for joint movement therewith by means;
extending through said opening, said ._sectmdY
‘being ofgsmaller effective varea than 'said't
Selsyn transmitter 40 is connected to a remote 30 ,member
Selsyn receiver 46 >in ther conventional mannen '-'ñrst member, a Vvalve element Aformed on said~
connecting means for cooperation with saidopen
Thus, the Selsyn receiver 45 ig responsive tothe
pressure differential acting' on the diaphragm 26
so that the rotor of the Selsyn receiver may drive
ing, 'the other side of said second member being
an indicator 4_8> calibrated to read the _ñow in con-_
vent for said third chamber, and meansv respon
sive to the pressurerdifferential across said sec-_;
duit I0.
Fig. 2 isa mcdincation of the system of Fig,y 1l
illustrating al different type of ‘ indicating >means
subjected to atmospheric pressure, a. restricted
ond member.
2. Apparatus for transforming a small fluid.
responsive to the differential- pressure acting on
pressure dilferentialinto _a larger pressure diifer- ,
the diaphragm 2,6. That portion of Fig. 2 similarY 40 ential comprising a housing, a first movablemem
ber dividing said housing into a pair of opposed
chambers, means for subjecting said chambers
tovFig'. 1 has been’designated by similar reference
numerals and no further description of this por
tion of the apparatus is deemed necessary.
In '
this modification the chamber 32 is connected
to a chamberjSU-by a conduit 5,2. lA flexible dia?
phrag'my 54v separates this> chamber fromv the at-_
lmosphere sothat this diaphragm'is subjected to
and consequently said movable member to said,
small pressure differentiaLa `third chamberfsep-`
arated from the high pressure chambenof, said
' pair of chambers by a fixed partition, a' second.r
movableA member of smallereffectivev area _than
said iirst member anddisposed across saidthird
the same pressure differential per unit area as
chamber, :means extending through, an yopening,
that acting against diaphragm. 26. A link arm 56'
connects the diaphragm 45'4 to a _liexibleV cantilever . 50 in vsaid partition and connecting said „members“V
beam ‘58 lso that the deflection yof this beam’ isl i for 'joint movement;v avvalve element Ymoi'fabley byn
said -connecting meansl and cooperating withklsa'id ’
proportional to the pressure differential acting
against d_iaphragms'Zû and 54. Y
opening for `controlling the transmission Vo_fj- pres
A pair of conventional granular` carbon type
sure from said hig'hpressure, chamber to sa_id„
ambientY temperature surrounding the apparatus'-
ible diaphragm to. said= small pressure differential,>
is eliminated. If'V the apparatus is being used to
the individualY pressures ofcsaid small pressure '
differential both, being greater than- atmospjneri‘cs- v
resistances 60 and` 62 are mounted on opposite 55 third', chamber and consequently‘to one side offY
said second member,A the oppositepside .of _said
sides of the beam 58 so that deflection of the`l`
second >`'member being subjected toa pressure less y
beam isA operative thru insulating arms 59 and' 6l
than either of the> individual pressures .of said '
to increase one of these resistances and decrease
small pressure differential, said third chamber
the other resistance. _These resistances form a
pair of' arms of a conventional Wheatstone bridge 60 having a restricted fluid pressure leakage path
therefrom, and `means responsive to the pressure.vv
circuit 64. A galvanometer 66 or other indicator
diiîerential across said second member.`
, Y
is connected across this bridgeV and may be cali-`
3, Apparatus for transforming a_ small pressure
brated to read the iiow invv conduit I0, since the
diiîerential into ka larger pressure differential:` '
deflection ofY beam 58 is proportional tothe pres--Y
comprising a housing, 'aofirst liexible diaphragm .
sure differential acting against the diaphragm 2'6.
vextending across said housing and Vdividing_said .
By'providing a pair of resistances 60 and B2op-`
housing into a pair of chambers, means for sub- i
positely responsive to the deflection of the beam '
jecting said chambers ¿and consequently said?lex'..Y
58 insteadV of justr one resistance, the effect of
measure fuel> flow to an internalcombustion en-`
gine„ elimination of the effect of ambient tem-ì
perature is q_uite important because 0f the varia-`
ì Y tion in temperaturev _of the engine under differ- ‘
ent Y operatingy conditions,
pressure, a third chamber in said'honsing and.v
separated from the high pressure_,vchamb„er„of.;
said pair of chambers by a ñxed partition,I z_tïsecç!l
76 - ond flexible diaphragm ofjY smaller'effective"area'4
than said first diaphragm and extending across
said third chamber, means extending through an
opening in said partition and connecting said
‘diaphragms for joint movement, a valve element
movable by said connecting means and cooperat
ing with said opening for controlling the trans
mission of pressure from said high pressure
chamber to said third chamber and consequently
to one side of said second iiexibie diaphragm,
the other side of said second -ñexible diaphragm
being subjected to atmospheric pressure, said
third chamber having a restricted atmospheric
vent, and a movable member responsive to the
differential >across « said second dia
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