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Патент USA US2301301

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Patented Nov. 10,. 1942
Robert L. Mallory, Houston, Tex., assignor to The
' Brown Instrument Company, Philadelphia, Pa.,
. .a corporation of Pennsylvania
Application October 7, 1939, Serial No. 298,419
(c1. rev-439)
understanding of the invention, however, its ad
My present invention comprises improvements
ogous control actuating element and which varies
vantages, and speci?c objects attained with its '
use, reference should be had to the accompanying
drawing and descriptive matter in which I have
illustrated and described a preferred embodiment
in accordance with changes in a control condi- '
of the invention.
in ?uid pressure control apparatus operating to
create a control ?uid pressure force which is im
pressed on a ?uid pressure control motor or anal
In the drawing:
tion, such for example, as a temperature, a pres
Fig. 1 is a diagrammatic view, partly in section,
sure, a height of liquid level, or a velocity, the,
showing one embodiment of my invention;
controlling condition usually, though not neces~
Fig; 2 is a view, partly in section of a second
sarily, being returned to, or-toward a normal 10
- value on a departure therefrom, by the operation
_ embodiment; and
Fig. '3 is a view of an embodiment having an
of said motor or analogous device. ~
other arrangement of the control nozzle.
Referring to the drawingthere is shown by
A main object of the present invention is to
provide certain speci?c improvements in ?uid
pressure controlling apparatus of the type com 15. way of example, a furnace l whose temperature
is to be controlled. The temperature of the fur
prising means whereby a departure in the value
nace is to be varied by regulating the heating
of a controlling condition from a predetermined
?uid therefor which is supplied through a pipe
or normal value thereof, varies an air or other
3 having a valve 4 in it. The valve is closed by '
elastic ?uid pressure control force, and whereby
such initial variation in the control force pro
duces a second control force adjustment quickly
eliminating more or less of the initial change in
the‘control pressure, and produces a subsequent
means of the pressure of a spring 5 and is opened
. varying amounts in response to pressure applied
to the h .per surface of a diaphragm 6.
Inserted in the furnace is a temperature re- '
sponsive bulb ‘I that is ?lled with a ?uid that
of the second adjustment isneutralized at a rate 25 expands upon an increase in temperature to cause
third control force adjustment by which the effect
' suitably retarded to insure the regulation or con
trol stability necessary to avoid hunting. Said
second and third adjustments are sometimes
referred to as “follow-up” and “compensating”
adjustments, respectively, and the third adjust
ment is also sometimes referred to as an auto
the expansion‘ of a Bourdon tube 8 to which it '
is connected by a capillary 9. The Bourdon tube
8 is of helical form and has its stationary end
attached to the capillary 9,‘ while its'movable
end is attached to and adapted to move a lever l0 clc‘kwise around a pivot II in response to .
temperature increases and to move said lever
counter-clockwise in response to temperature
In such control apparatus, the extent to which
theinitial control pressure adjustment is neu
tralized by the second adjustment, and the rate 35 Through suitable connections the operation of
at which the third adjustment ‘neutralizes the ' the lever l0 gives motion to a ?apper valve I2,
which as shown, forms part of a control pressure
effect of the second adjustment, should be capa
regilator, or air control unit It, and regulates
ble of regulation or calibration to enable the
the escape of air therefrom, and thereby regu
apparatus to give desirable results under varying
40 lates the control air pressure in a regulator
conditions of operation.
chamber I4, The latter receives air through a
.Another main object of the present invention
pipe I5 and a restriction 16. The pressure in
is to provide an air control instrument by which
matic resetting adjustment.
the above mentioned movements are accom
plished in a simple manner by the use of an abso
lute minimum of parts. In my invention a single
‘ bellows that is subjected to variations in air pres
sure on its opposite sides as a result of'a change
in the value of the condition being measured and I.
the chamber I4 is transmitted through the pipe
l5 to the control chamber of a booster valve l1.
Booster valve H is supplied with air under
regulated pressure from pipe l8 to a controlled
pressure chamber i9. Pivoted within the cham
ber IB' and attached to a diaphragm 20, forming
one wall of the control chamber, is a valve 2i
controlled is used to operate mechanism that
provides the follow-up and compensating move 50 that moves between the air entrance of pipe “I
and an exhaust duct 22. Diaphragm 20 is sub
The various features of novelty which charac
terize the present invention are pointed out with
particularity in the claims annexed to and form
ing a part of this ‘specification. For a better 55
jected to opposing pressures, namely that in
chamber M and that in chamber I9 to ‘move the
valve‘2-l between the inlet and exhaust openings
to thereby maintain the pressure in chamber l9
proportional to that in chamber ll. A pipe II
connects the chamber is to the control valve 4.
All of the above mentioned parts except the
furnace I, valve 4 and bulb ‘I, are advantageously
proportional to the temperature increase in the
combined in a control instrument which 'may
well be a recording meter similar in form to a
initial temperature change results from and is
commercial type meter used for recording tem
peratures and pressures. Such a meter may
include a casing, chart plate, chart, and chart
driving motor together with a hinged door, which
reduction in chamber H. Due to the pressure
reduction in chamber I l the bellows 48 expands
simultaneously shifting rod 48 to the right. As
the rod 48 moves the member 38 is also shifted
to the right so that bell-crank 34 and pin 33
for sake oi clearness, are ‘not shown herein.
The second or follow-up movement oi.’ the in
strument that is produced as a result of the
practically contemporaneous with the pressure‘
will let the ?apper return toward its initial posi
tion, thus tending to neutralize the original pres
sure change. The net eilect oi the initial and
‘ment thereby in accordance with temperature 15 iollow-up adjustments following any particular
departure of the pen from its normal position
changes in the furnace. An arm 28, extending
from the pen arm 25, is connected by a link ' is a corresponding definite change in the control
pressure and a‘ corresponding de?nite position
28 to one end of a ?oating lever 38 that is nor
mally pivoted at its right end. The ?apper I:
for the valve 4.
that is pivoted at ll, on a support 32 extend 20 In order to compensate for the temperature _
increase to bring the value of the iumace tem
ing from the control unit II, is given movements
proportional to the temperature changes of the
perature back to the control point, the instru
furnace I by means 01' a pin 33 that is project
ment, as a‘ result of its second movement, is
ing from One arm of a bell-crank lever 84 which . given its third or compensating movement. As
has its other arm pivotally connected to the 25 the bellows 48 expands due to a decrease in pres
center or lever 38. The bell crank 34 is sup
sure in the chamber H the volume of chamber
4| will increase and decrease the pressure in
ported tor movement at 38 around the lower
that chamber. This pressure change in the
end of a lever 38 that, along with the ?apper
The meter recording pen 28 is mounted on the
lower end of an arm 2!, pivoted at 28, and con
nected by a link 21 to the lever N for move
is pivoted at 8|.
chamber 4|, however, is so small as to be negli
The unit It comprises a cup-shaped casing 30 gible, so that the pressure in that chamber is
still considerably above the reduced pressm'e in
member 31 that is closed by a head 38. Pro
iecting from the head is a nozzle I! which com
chamber It. The air in chamber 4| therefor
starts to pass through the duct 48, at a rate
municates with the chamber‘ l4 and is variably
controlled by the adjustment of restriction 48,
throttled by the ?apper valve l2. Within the
casing 31 and attached to the head 88 is an 35 into the chamber H. As this continues pres
sures in the chambers II and It are equalized
extensible bellows 48 that has a rod 4! attached
and the bellows 88 returns approximately to its
at. one end to its head; the other end of the
normal length moving the ?apper away from the
rod being pivotally connected to the member
nozzle or toward-its original position, again re'38. The head 89 is provided with an opening
through which the rod 88 extends, this opening 40 ducing the pressure hi chamber ll. Bellows 88
being. in effect, closed to form a second chamber‘
at the termination of the compensating action.
‘will be displaced from its initial position by an
4! by another and smaller sealing bellows 82.
' amount depending upon the amount of air which
The sealing means for chamber 4| is conven
is transferred from chamber ll to chamber l8
iently shown as the small bellows 42, but may,
if desired, take the form of a limp diaphragm 45 during the interval that the bulb ‘l was above
its normal value. This is in turn dependent upon
or an ordinary stu?'lng box. The bellows I2 is
the original pressure change in chamber I 4 and
attached to the rod 80 so that the two bellows
48 and I! move together as the bellows 88 is
the relative areas of bellows l8 and 42.
the amount of unremoved iollow-up-or the dis
expanded or contracted due to pressure changes
in thechamber ll. The chambers 14 and 4| 50 placement between the position of lever 38 at
the end of the follow-up movement and the end
are connected by a'duct 43 in which is located
a variable restriction 44 that may be adjusted
of the compensating movement may be varied
to change the rate at which pressures in cham
by varying the area of bellows 42. The less the
hers I8 and 4| may equalize.
area 01 bellows 42 the smaller the unremoved
'In the operation of the device, assuming an 55 follow-up will be. At this time, assuming that
increase in the temperature of the furnace above‘
the decreased pressure in chamber II has caused
its normal value, the Bourdon tube 8 will be
sumcient closing of valve 4, that the tempera
expanded to move lever I8 clockwise and, through
‘ture has returned to its normal value, equilibrium
link 21, move‘the pen 24 outwardly along the
of the apparatus with the bellows 48 and 42 at
chart (not shown). This movement will ‘cause 60 substantially their normal lengths is obtained '
the lever 88 to be moved clockwise around its
with a pressure in chamber l8 di?'erent from
right end to lift the left end oi’ bell-crank 34
the pressure in that chamber at the commence
ment of the operations just described.
and move that lever clockwise so that pin 33
Provision is made to change the control point
rwill raise the ?apper I! from the nozzle :9,
against the bias or spring 48. This movement 65 of the instrument, or the normal value or the
temperature in the furnace l by altering the
of the ?apper will permit more air to escape
original position of the ?apper l2 relative to
from the chamber l4, lowering the pressure in
the nozzle 38. This is accomplished by ad
that chamber and on diaphragm 28. As a result
lusting the right end of the lever 38 that is
of the decreasein pressure on 28 the valve mem
supported by a link 10 from one arm ‘ll oi’ an
ber II will close the inlet to chamber l8 and
index member 12 that is also pivoted at 28. The
open the exhaust port 22 and reduce the pres
sure in that chamber and line 23. A consequent
pressure reduction will occur on diaphragm 0 so
that the spring I will close the valve an amount
index member is adapted to extend down in
front of the chart to indicate thereon the value
at which the instrument is set to maintain. In
order to adjust the index 12 there is provided a
ing movement takes place.
knob 13 having a crank arm'll thereon which
is connected to the upper end of the index by
a links". When the knob 13 is rotated the index -
‘l2 will‘be moved across the chart to the de
sired point and at the same time link ‘II will
be raised or lowered, as the case may be. to
shift, the initial position of lever '30 and bell
crank 34- to control ?apper l2. Thereafter the
By the use of the _
springs l1 and ll the etiect of the relative areas
of the bellows ll and II is somewhat removed
as the tendency for l! to return to its normal .
length is more pronounced. In this embodiment.
also, the speed of compensation is regulated by
the adjustment oi the restriction M. which ad
justment should bear a relation to the time lag
of the process being controlled. In other words
Bourdon tube‘ tends to maintain the ?apper in
its initial position and the temperature 0! vthe 10 it may be said that. ordinarily the time required ,
for effecting thev automatic resetting or com
furnace at the control point.
pensating adjustment should increase or de
The embodiment of the invention disclosed in
Fig. 2 is essentially the same as-that of Fig. 1. ‘ crease in accordance with the rate at which
change in the controlled process or operation
but differs therefrom in certain constructional
details whose purpose will be set forth below.
In the above described embodiments of the
In the form of the invention of Fig. 1 the nat
invention the nozzle 30 has been shown in com
ural resiliency of the bellows I! was used to re
munication with the chamber II. This is not
turn those'bellows to their normal length dur
necessary and another manner in which pres
''ing the compensating movement as the pres
sure in chamber I‘ may be adjusted is shown
sures in chambers II and il equalized. At times
'in' Fig. 3. In that ?gure the nozzle 39A issup
it is desirable to use some auxiliary force to
plied directly with‘ air from the line it that
return the bellows to their normal length. To
also communicates with the diaphragm 20.
this end the head to thafcloses the bell shaped
casing in‘Fig. 2 is formed with an'inwardly ex-‘ ‘ Thus changes in pressure as a result oi- move
tending cup-shaped portion II having an open 25 ment of flapper l2 relative to the nozzle "A
only serve to move the valve member II to ad
ing through its bottom wall. Fastened to the
just the pressure in chamber Ii. Aspressure
bottom wall of the part Si is one end of a bel
changes in chamber II are applied to the con
lows member 52 whose other end is attached to
trol valve diaphragm through line 23, this same
a plate Ill that has an opening therethrough.
The open end of a bellows M is attached to 80 pressure is applied to the chamber l4 throng
. a line “a connecting with line It. ‘
the other face of the plate I! while the closed
The mechanism located in casing 31 in this
end of the bellows is held in a given position
figure may take the form of either Fig. 1 or Big.
by its attachment to a U-shaped member 5!
2. In either case the~operation is the same as
that straddles the bellows and is attached to
described for that embodiment.
the face of head 50. Because of the openings 35 above
While in accordance with the provisions of
in plate It and the bottom wall of the portion
the statutes, I have illustrated and described the
ii. the interior of bellows i2 and I‘ are in com
best form of embodiment of my invention now
munication with the interior of bellows 40 to
known to me. it will be apparent to those skilled
form a chamber 56 corresponding to the cham
in the art that changes may be made in the
ber ll of Fig. 1.
form of the apparatus disclosed without depart
Located within the bellows t2 and tending to
ing from the spirit‘of my invention as set forth
force that bellows toward a longer length by
in the appended claims and that in some cases
means of its engagement with portion II and
certain features of my invention may be used to
plate 83 is a spring '1. In a like manner a
advantage without a corresponding use of other
spring 58 is located in the bellows II to abut‘
against plate ti and oppose the spring 51. Be—
Having now described my invention, what I
cause of the springs 51 and 58 the plate It is
claim as new and desire to secure by Letters ‘
at all times resiliently biased toward a 'given
Patent. is:
i. In an air control instrument the combina
The connection between the bellows 40 and 50 tion
of a cupsshaped casing. a bellows extending
member 38 whereby movements of. that bellows
the same to form a chamber therein, a
may move the ?apper valve l2 comprises a rod
second bellows forming with the ?rst bellows and
59 that is attached to the bellows and the plate
casing a second chamber. a re"tricted passage
81. This rod passes through the opening in~
portion 5i and the spring '1. A yoke member 55 way between said chambers, a supply of air and
an exhaust nozzle for said first chamber. a nap
Cll surrounds the bellows “and is attached to
per valve for said nozzle. means responsive to
the plate 53 for movement therewith. The
the variations in the value of a condition to ad
movement of yoke 80 is transferred to member
just said valve relative to said nozzle to thereby
3! by means of a rod II.
vary the pressure in said chamber, and means
The operation of this embodiment of the in
extending through the second bellows and at
vention is essentially the same as that above de- .
tached to said ilrst bellows operative upon move
scribed in connection with Fig. 1. Upon move
ment of said ?rst bellows in response to a pres
ment of the flapper it away from nozzle to
sure change in the first chamber to readjust the
more air can escape therefrom to reduce the
pressure in space It and cause an expansion of 65 valve in a reverse direction.
2. In an air control instrument, the combina—
the bellows 48. Such expansion will shift bell
or a cup-shaped casing. a bellows extend
crank 34 to the right by means of the connec
ing into said casing and attached at its open
tions including rod I9, plate ‘I, yoke Oil and rod
end- to the open end of said casing to form be
II, and at the same time will compress the
tween the two an expansibie chamber, a second
spring 51. Upon a contraction of the bellows
bellows fastened at its open end to the open end of
- 4| the spring 58 would have been compressed
said casing and in opposed relation to said ilrst
by the plate 53. In either event the force of v bellows to form a second expansible chamber
one of the springs 81 or 50 is added to the nat
therebetween, a rod extending thorugh the end
ural resiliency'of the bellows 48 in returning that
of said second bellows and rigidly connected to
bellows to its normal length as the compensat
the ends of each bellows, a restricted connection
between said two chambers, a supply of pressure
‘?uid for said ?rst chamber, an exhaust nozzle
for said ?rst chamber, a valve cooperating with
said nozzle to regualte the flow oi’ pressure ?uid
therethrough, and means jointly actuated by vari
ations in the value of a variable condition and
by said rod to move said valve relative to said
chamber, an exhaust port in said one chamber,
an exhaust valve tor said port, means to Jointly
move said exhaust valve comprising a part moved
to a position proportional to the value 01' a
condition and a part connected to said movable
wall whereby upon movement or either part the a
pressure in said one chamber and said controlled
valve mechanism will be-varied, a restricted
connection between said two chambers and means
tending at all times to move said movable wall
to a given normal position.
3. In an air control instrument a cup-shaped
casing open at one end, a bellows extending into
said casing and attached to the same at said
end to form between the casing andv bellows an
. 6. An air control system comprising a con
expansible chamber varying in size as the pres- -.
sure in said chamber changes, a second bellows
also attached to said casing at said end- and
forming with the casing and ?rst bellows a sec- '
ond expansible chamber, a rigid connection be
tween said two bellows’ and extending beyond
the second one, a restricted connection between ,
‘ said two chambers whereby a pressure change
trolled valve' mechanism, and a control unit hav
ing a closed casing and a movable wall therein
forming a pair of chambers, means including
a restriction for supplying air simultaneously to
said controlled valve mechanism and one of said
chambers, a supply 01' air passing through said
restriction, an exhaust valve regulating the ex
haust or air from said controlled valve mech
anism and said one.chamber and thereforethe '
in one is slowly communicated to the other, a'
source or ?uid under pressure communicating
pressure in them,'means including means at
valve in response to variations in the value of
to cause the controlled valve mechanism‘ and
said movable wall to assume positions corre
tached to and actuated by said movable wall and
with said ?rst chamber, a bleed nozzle for the
?rst chamber, a valve adapted 'to regulate the .' means movable in accordance with the value of
bleed through said nozzle, means to adjust said - a condition for positioning said exhaust valve
a variable condition to thereby change the pres
sure in said ?rst chamber andthe length of said
bellows and means operated by said rigid con
nection to give a reverse movement to said valve.
4. In an air control instrument, the combina
tion of a casing, a bellows extending into the
same to form therewith an expansible chamber,
a second bellows cooperating with said casing and
?rst bellows to form a second expansible cham
ber, a variably restricted connection between
said chambers, a source or pressure ?uid for said
?rst chamber, an exhaust nozzle for the ?rst
chamber‘, a valve for said nozzle to variably .re
strict the ?ow therethrough and thereby vary
the pressure in said ?rst chamber and the length
of said bellows,,means operative upon variations
in a variable condition to move said valve rel
ative to said nozzle to change the-pressure in the
first chamber, and means rigidly connected to
both bellows to move said valve in a reverse di
rection in response to said pressure change. >
5. An air control system comprising a closed
casing‘provided with a movable wall therein di
viding the same into .a plurality of chambers
whose size varies in accordance with the position
of said wall, a controlled'valve mechanism, a
connection between said‘ valve and one of said
chambers whereby the pressure in the two is the
same, a supply of air under regulated pressure
for the controlled valve mechanism and said one
sponding to the valueoi the condition, and means
including a restriction i'orequalizing the pres~
sure on opposite sides of the movable wall to
cause the controlled valve mechanism to be addi-e ,
tionally positioned with respect to the value of
the condition.
Y' 7. Anair control system comprising a con
trolled valve mechanism and a control unit hav
ing a closed casing and a movable wall therein
vforming a pair of chambers variable in size.
means including a restrictionthrough which air
is simultaneously- supplied to said control valve
"mechanism and one of said chambers, a supply
of air passing through said restriction, an ex
haust port for‘said chamber and controlled valve
mechanism, an exhaust valve regulating the ?ow
oi’ air-through said port, means operated in re
sponse to‘variations in the value of a ‘variable
condition to adiust said valve and thereby change
> the pressure in said one chamber and controlled
valve mechanism, whereby said movable wall will
be shifted, a mechanical connection, between said
‘ movable wall and exhaust valve operative upon
movement of said wall to move ‘said exhaust
valve, a restricted connection between said two
chambers and meansat all times tending to move
said movable wall to a normal position upon its
displacement therefrom. ‘
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