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Патент USA US2411574

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Nov. 26, ‘1,946.
2,41 1 ,574
N s. F. HUNT
‘PUMP CONTROL WITH LINE LOSS COMPENSATION
Fi1_ed March 6, 1944
INVENTOR.
1.5522777’ Flinn‘
I
..
A.
2,411,514
‘aténted Nov. 26, 1946'
UNITED STATES PATENT OFFICE
2,411,574
PUMP CONTROL WITH'LINE LOSS
'
COMPENSATION
,
Scott F. Hunt, Meriden, Conm, assignor to
Chandler-Evans Corporation, South 'Meriden,
Conn., a corporation of Delaware
Application March 6, 1944, Serial No. 525,160
6 Claims. (Cl. 103—42)
1
This invention relates to means for maintain
ing a constant pressure in a ?uid supply line at
a point remote from a pressure creating device.
2
I constant pressure, and the inner one of which is
directly connected to the space within the fuel
pump above the relief .valve diaphragm.
In‘ the operation of fuel pumps which normally
are set for a predetermined pressure, the delivery
point of the pumped fuel may be at a consider
able distance from the pump and subject, there'
More particularly the invention relates to a
device or means for maintaining the pressure
within the feed line of an' aircraft engine at
constant pressure at the carburetor intakes when
they are at a distance from the fuel pump.
A feature of the invention that enables the
above object to be accomplished is that a vari
able pressure is applied to the pump relief or‘
fore, to a pressure drop due to the velocity of
?ow through the interconnecting conduit. With
variations of velocity within the delivery conduit
this drop in pressure may vary substantially. It
is therefore an object of the invention to provide
by-pass valve so that when the pressure at any
simple but e?icient- means whereby the pressure
predetermined point in the delivery line of the
at any control point in the delivery conduit of
pump varies, the pressure delivered by the pump
may be varied to maintain the pressure at the
a pump can be maintained at constant pressure
under varying conditions of flow through the
predetermined point constant.
‘ Another object of the invention is to provide
a pressure ampli?er at the point in the line de
sired to be maintained at constant pressure so
that a variation in pressure at this point mayv
conduit.
be converted into an ampli?ed pressure change
and this latter pressure applied to supplement
In order to control the pressure delivered by this
Referring more in detail to the ?gure of the
drawing, it will be seen that a pump Ill of the
rotating radially movable vane type is provided
which may be rotated by any means (not shown) . .
pump a relief or b’y-pass valve vl I is biased toward
the loading of the fuel pump by-pass valve.
‘closed position by a spring l2, the pressure of
which may be adjusted as required.
With the above and other objects in view the
invention may include the features of construc
tion and operation set forth in the following
In the form of pump shown in the drawing a -
?exible diaphragm I3 is provided in a portion
of the pump casing against which the spring l2
speci?cation and illustrated in the accompanying
operates so that the diaphragm l3 forms a ?exi
- drawing.
In the accompanying drawing annexed hereto
and forming a part of this speci?cation, I have
shown the invention embodied in the delivery
line of a standard type of fuel pump but it will
be understood that the invention can be other
wise embodied and that the drawing is not to be
construed as de?ning or limiting the scope of the
invention, the claims appended to this speci?ca
tion being relied upon for that purpose.
In the drawing. the ?gure shows a cross sec
tional view of a fuel pump having a pressure
,- ampli?er in its delivery line at a point remote
from the pump.
In the above-mentioned drawing there has
been shown but one embodimentof the inven
tion which is now deemed preferable, but it is to _
be understood that changes and modi?cations
may be made within the scope of the appended
claims without departing from the spirit of the
invention.
_
,
Brie?y, and in its preferred aspect, the inven
tion may include the following principal parts:
First, a ‘fuel pump which may be of standard
type having a relief valve incorporated therein,
the pressure acting against which may 'be sup
plemented by increasing or decreasing the pres
ble seal for the pump and permits movements of
'
The space within the casing of
the valve H.
the pump Ill above the diaphragm I3 is closed
as by means of a bonnet member I4 and a cap
member l5 threadedly attached to the upper
portion of the bonnet l4. To vary the pressure
of the spring l2 acting on the diaphragm l3 and
‘by-pass valve II the upper end of the spring l2
bears against a pressure plate l6 suitably guided
within the bonnet member ll, the position of
which may be varied by adjustment of a screw I'I.
At the control point, a pressure ampli?er 20
is provided of the multiple Sylphon bellows
' type. It will be noted that there are two ?exible
metal bellows 2| and 22. one within the other, the
space within the outer bellows 2! being connect
ed directly to the delivery pipe 23 by means of
a vbranch conduit 24. Enclosed within this bel
lows is the second bellows 22 of much smaller
diameter than the ?rst and this bellows has its
interior space directly connected by a conduit 25
extending to the-space within the pump casing
Ill .and directly above the ?exible diaphragm IS.
A spring 26, the pressure of which may be varied
by adjustment of screw 21, presses against the
upper surface of the inner'and outer bellows to
sure above a ?exible diaphragm connected there
‘vary the pressure acting thereon. Movement of
to; second, a pressure amplifier comprising Syl
the outer bellows 2| by variations of pressure in
phon bellows, one within the other, the outer
discharge conduit 23 causes the inner bellows 22
one of whichis connected to the delivery line of
to -move correspondingly. Both bellows have
' the pump at the point hereinafter referred to as 60 their end walls attached together and are free
the control point, desired to be maintained at a
2,411,574 '
3
to expand and contract by movement upward
3. A pressure maintaining device for pump
and downward of their upper ends against the
pressure of spring 26.
, It will be seen from the
'-
discharge conduits comprising, _a1pump ‘having
'
a pressure controlled by-pass valve, means to ad
above description that
charge line 23 of the pump will reduce the pres
just the pressure vacting on said valve, pneu
a slight reduction‘ in pressurewithin the dis- .
matic means to supplement the pressure acting
sure within the outer bellows 2| and cause this
member to correspondingly compress the inner I
bellows 22 which will increase, the. pressure»
on said valve, and a pressure ampli?er connect- ,
ed to said conduit at a point remote from said
pump, said amplifier‘ having a bellows subjected
therein. This increase in pressure within bel 10
lows 22 will act‘ directly upon the '?ex'ible ’di-_ "
_
sure therein, whereby, the pressure ot'sald pneu
aphragm l3 of the pump. “This increased pres
matic
means
will
sure upon the ?exible diap agm I3 ‘will there
be varied :with variations of
pressure .within said discharge line. '
1 v
fore hold down the bypass valve II with a cor
4. Apparatus for regulating the discharge"
pressure and thus cause 15
pressure or a pump which‘ discharges thru a long '
the pump II) to correspondingly increase its de
' respondingly increased
.
'
livery pressure. Similarly‘ when the pressure at
conduit, comprising a-reliei valve subject to the
the ?exible diaphragm 13. The discharge pres
sure will therefore be reduced proportionately to
responsive to the pressure in said conduit at a
pump discharge pressure,,a spring biasing said
the control point increases the capacity of the
relief valve closed against the action of said dis
outer bellows will increase’ and force the inner
bellows to expand. This movement of the inner 20, charge pressure, an expansible chamber having
a movable wall connected to said valve so that
bellows 22 decreases the pressure within the in
ner bellows and reduces the-pressure acting on
the pressure in said chamber acts on said valve
in. opposition to said discharge pressure, means
,
_
point remote from said pump for producing a
control pressure greater than said conduit pres
sure and for varying said control pressure op
the increased pressure at conduit‘?.
The area at the free end of bellows 2| on which -
the pressure within that bellows acts upwardly
is greater than the area on which the pressure
positely. and proportionally with variations in
within bellows 22 acts upwardly. Therefore, it
said conduit pressure, and means for communi
may be seen that a given change in pressure
to vary said pump discharge pressure in a sense op
' - cating said control pressure toysaid chamber to
within‘ bellows ‘2| produces an inversely propor
tional, but greater change in pressure within bel
lows 22..
Any change in pressure at the control point
thereby causes an ampli?ed inverse ‘change in 35
pressure above the diaphragm l3. For example,‘
if the pressure at the control point decreases, the ~
. pressure above diaphragm
l3, and hence the ~
posite to the variations in said conduit pressure
so as to compensate for the pressure drop invsaid
conduit between said pump and said pointand
thereby to maintain ~ a substantially constant
pressure at said point.
'
‘
5. Apparatus for regulating '- the" discharge V
pressure of a pump which discharges thru a long
pump discharge'pressure, is increased by a greater ' conduit, comprising a relief valve subject to the
amount.- This greater increase in the pump dis 40 pump discharge pressure, aspring biasing said
relief valve closed against the action of said dis
charge pressure not only counteractsthe original
charge pressure, an expansible chamber having change in pressure at the control point, but also
a movable wall connected to said valve so that
the pressure in saidcham-ber acts on said valve
counteracts the increased friction lossesin the
- line due to the increased ?ow therethru at the
in opposition to said discharge pressure, means
higher pressure.
By properly adjusting the
point may beheld substantially-constant.
45 responsive to the pressure in said conduit at a
screws H and 21, the pressure at the control
point remote from said pump for producing a
The variations in pressure within the conduitv 1 Y control pressure varying oppositely with vari
ations of said conduit pressure, and means for
23 therefore cause variations in pressure within
communicating said control pressure to said
the valve casing above the ?exible diaphragm is '
chamber to vary said pump discharge pressure
which will add to or subtract from the pressure
of the spring l2 acting on the valve H and thus
will vary the pressure of the ?uid delivered by‘ '
the pump.
I claim:
1. A pressure maintaining device for pump
discharge conduits comprising, a pump having a
pressure controlled by-pam valve, means to ad
just the pressure acting on said valve, pneu
matic means to supplement the pressure acting‘
on said valve, and a
pressure , ampli?er connect- '
ed to said conduit ‘at/a point remote from said
pump to vary the pressure of said pneumatic
means with variations of pressure within said
in a sense opposite to the .variations in said con-- ,
t) duit pressure so as'to compensate for the pres
sure drop in said conduit between said pump and,
said point and thereby to maintain a substan
tially constant pressure at said point.
'
6. Apparatus for regulating‘v the’ discharge
pressure of a pump which discharges thru a long
conduit, comprising a relief valve subject to the
pump discharge pressure, a-spring biasing said
60 relief valve closed against the action of said
discharge pressure, an expansible'chamber hav
ing a movable wall connected to saidv valve for
applying'a variable, control force thereto, means,v
responsive to the pressure in said conduit at a
2. A pressure maintaining device for pump '65 point remote from said pump for producing a
control pressure varying as a function or said
discharge conduits comprising, a pump having a
conduit pressure; and means for communicating
pressure controlled by-pass valve, means to ad
said control pressure to said chamber to vary
just the pressure acting on said valve, pneu
said pump "discharge pressure in a sense oppo
matic means to supplement the pressure. acting
on said valve, and a pressure, ampli?er connect 70 site to the variations in said conduit pressure so
as to compensate for the pressure drop‘ in said
ed to said conduit at a point remote ‘from said
conduit between said ‘pump and said point and
pump to increase the pressure or said pneumatic
thereby‘ to maintain a. substantially constant
' means proportionately to a reduction of pressure
' pressure at said point.
within said discharge conduit.
75
discharge conduit.-
'
_ sco’rr F.
I
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