Dec. 29, 1953
K. R. DAvu-:s ETAL
2,664,152
FUEL SYSTEM FOR GAS TURBINE ENGINES
Filed May 11, 1948
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2,664,152
K. R.' DAvlEs ET AL
FUEL SYSTEM EOE GAS TUREINE ENGINES
Filed May l1, 1948
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K. R. DAvn-:s ErAL
2,664,152
FUEL SYSTEM FOR GAS TURBINE ENGINES
Filed May 11, 1948
v
4 Sheets-Sheet 3
Dec. 29, 1953
K. R. DAvn-:s ETAL
2,664,152
FUEL SYSTEM FOR GAS- TURBINE ENGINES
Filed May ll, 1948
4 Ísneets-sheet 4
Patented Dec. 29, 1953
;
2,664,152
UNITED STATES PATENT OFFICE
2,664,152
FUEL SYSTEM FOR GAS TURBINE ENGINES
Kenneth Roy Davies, Radbourne, near Derby,
and Karl Herbstritt, Littleover, Derby, Eng
land, assignors to Rolls-Royce Limited, Derby,
England, a British company
Application May 11, 1948, Serial No. 26,423
Claims priority, application Great Britain
Mayl 12, 1947
7 Claims.
1
(Cl. 15S-36.4)
2
This invention relates to fuel systems for gas
turbine engines. A particular application of
ther invention is to such engines as used for air
craft propulsion purposes, Where variations of
operational altitude give rise to corresponding
changes in fuel consumption.
This invention has for an object to provide
gine is obtained for a setting of the speed se
, _lecting device, corresponding to maximum speed.
Alternatively or additionally the altitude respon
sive device may be arranged at low-speed settings
of the variable restricting means to vary the
pressure drop to increase the change in engine
speed with change in altitude attributable to the
a. fuel system (hereafter referred to as a fuel
run-up range.
system of the kind specified) comprising control
means including a constant volume hydraulic
pump driven at a speed proportional to engine
speed and passing liquid through restricting
means which can be varied by an engine speed
selecting device, and pressure responsive means
normally responsive to the pressure drop across
said restricting means operative to effect vari
ation of fuel delivery to the engine to main
tain the selected speed.
In such a fuel system, for any given setting
of the variable restricting means there is a range
of engine speed (referred to hereinafter as the
“run-up” range) required to vary the fuel de
livery from a maximum to a minimum. Further
more, the fuel consumption of a gas-turbine en
This arrangement may be de
sirable with a control-lever setting correspond
ing to idling engine rotational speed to avoid
the possibility of extinction of the flame in com
bustion equipment.
Such ambient pressure or altitude responsive
tu
means may comprise a valve or restriction ar
ranged in series or parallel with the variable
restricting means, and controlled by a barometríc
capsule, subjected to ambient pressure, or a func
tion thereof which may be correlated with air
craft or engine speed. Alternatively the am
bient pressure or altitude responsive means may
be arranged to effect relative movement of parts
defining the variable restricting means, e. g. a
barometric capsule may be arranged to effect
movement of a valve seat, or a valve plunger, or
gine decreases for a given engine speed as the
‘ may be incorporated in linkage as between the
operating altitude increases or the ambient pres
sure decreases. Thus it will be seen that with
a given setting of the variable restricting means,
a decrease in the ambient atmospheric pressure
will result in an increase in engine speed cor
speed selecting lever and the orifice restricting
responding to the difference in fuel deliveries at
the original andV new altitudes orl ambient pres
Eures.
means.
The invention may additionally provide in
combination with the means responsive to change
of altitude or ambient pressure, means sensitive
to the rotational 'speedr of the engine. Such
additional means sensitive to the rotational speed
of the engine may comprise 9, pressure sensitive
The present invention has for another object
to provide an improved fuel system of the kind
specified in which undesirable ellîects arising
from the run-up range with varying conditions
device subjected to pressure drop across a fixed
the Variable restricting- meansv so as to. varyv the
tor arrange the control means to have a run-up
orificev through which the hydraulic pump driven
at a speed proportional to engine speed passes
liquid, whereby such pressure drop is a function
of altitude or ambient pressure are avoided.
of the engine speed. Alternatively the nxed
According to the present invention a fuel. sys
orifice may pass the actual fuel delivery to the
tem of the kind specified for a gas-turbine en» 40 engine, whereby the pressure drop is a function
gine includes means responsive to changes of
of engine speedv and altitude.
altitude or ambient pressure and associatedwitb
Tov obtain stability of control, it is preferred
pressure> drop in accordance with changes of
range which may for example amount to 5 to 20%
ambient pressure or altitude and. thereby to vary 45 of thev selected speed. In this manner it becomes
in a desired manner the fuel supply to the en
desirable to include means in accordance with the
gine.
invention to compensate for or to accentuate (if
The provision of the ambient pressure or
desired) variation between actual and selected
altitude responsive means permits undesirable
speed, which are attributable to the run-up range
effects of the run-up range oi enginer speed to ' and variation of altitude. or ambient pressure.
be avoided. Thusy the ambient pressure or al
The: following describes by» Way of example of
titude responsive means may be arranged to
this invention, control means suitable for a
modifyv the pressure drop across the. variable
gas-turbine engine fuel system.
restricting means, in` a manner such. that. sub
stantially uniform rotational speed. of the en.
The~ description refersA to the accompanyingv
diagrammatic drawings» in which
2,664,152
3
Figure i illustrates the control means and a
part of the fuel system,
Figure lA illustrates a typical gas-turbine
engine and variable delivery fuel pump for de
livering fuel to the engine.
Figures 2 to 5 illustrate graphically the action
of the control means, and
Figures 6 and 7 illustrate modifications of the
4
orifice I8 is controlled by a needle valve I9,
the position of which is determined by a manu
ally-operated lever 20 connected to the pilot’s
speed selecting lever.
A branch 2l is taken from the pump delivery
pipe-line 22 to the cylinder I4 so that the delivery
pressure of the pump is applied tothe piston I3
to oppose the spring I5, and a branch 23 is taken
from a pipe line 24 downstream of the orifice I8
Referring to Figure 1A there is illustrated a 10 to the opposite end of the cylinder I4.
The position of the piston I3 in the cylinder
typical gas-turbine engine 60 and a variable
I4
is thus determined by the pressure drop
delivery fuel pump I0 for delivering fuel to the
control means.
across the orifice I8 and is thus a function of
the engine speed and of the effective area of
sor 6l which delivers compressed air into a 15 the orifice. Furthermore, an increase in the
pressure drop causes a decrease in the stroke of
series of combustion chambers B2 which are
the fuel pump I0 so that the needle valve I9 is
disposed in a ring around the engine and of
arranged to increase the effective arca of the
which two only are shown, a fuel delivery mani
orifice to increase the engine speed.
fold connected with fuel injection devices I2 for
With the control arrangement above described,
delivering fuel into the combustion chambers E2
rapid
opening or closing movement of the control
wherein the fuel is burnt, a turbine (not shown)
lever would produce a substantally instantaneous
which receives the combustion products from the
decrease or increase in the pressure drop applied
combustion chambers 62 and drives a shaft 63
to
piston I3, and this in certain circumstances
carrying the compressor rotor.
will
give undesirable characteristics to the fuel
25
The fuel is delivered to the fuel injection de
delivery of the pump I0. For instance, if the
vices I2 by the variable delivery fuel pump III
engine is running at low speed and the control
through a delivery pipe IBA, the pump being
lever
is moved rapidly to the full throttle posi
driven from the shaft 63 through a drive indi
tion, the pump I0 would be substantially instan
cated at 1 I.
The fuel pump l!) as illustrated comprises a 30 taneously moved to full-stroke with the result
that over-fuelling of the engine may occur.
body G4, a rotor 66 accommodated within the
Over-fuelling can give rise to excessive tem
pump body E4, a plurality of plungers 65 which
perature in the engine combustion equipment
reciprocate in bores B9 in the rotor 66 against
and turbine, and possibly also to surge in the air
the action of springs 'IO and means to adjust the
compressor of the engine or to extinction of the
stroke of the pump plungers 65 to vary the de
fiame. Again, if the control lever 2U is closed
livery of the pump. The means to vary the de
rapidly a rapid increase occurs in the pressure
livery of the pump in the construction of pump
drop, applied to piston I3 with a correspond
illustrated comprises a swash plate II carried on
ingly rapid decrease in the fuel-pump stroke to
the crank portion of a spindle G8 which is
axially movable with respect to the pump rotor " its minimum stroke. This can result in extinc
tion of the fiame in the combustion equipment.
5S. As the spindle 68 is adjusted axially of the
These disadvantages are overcome by provid
rotor the inclination of the cam face of the
ing means to limit the maximum and minimum
swash plate I! with respect to the rotor axis
pressure drop that can occur across the orifice
varies thus altering the stroke of the pump
I8. The pressure drop limiting means comprises
plungers. In operation, on rotation of the
a lift valve 25 which is loaded by a spring 2'3
rotor
through the drive 1I fuel is drawn in to
and is arranged in the pipe-line 22 between the
the pump bores through a suction pipe IDB by
point
of connection of the branch 2I and the ori
the pump plungers 65 riding up the cam face of
fice I8. The valve element 25 is conveniently
the swash plate Il under the control of springs
‘i8 and subsequently the fuel is delivered into 50 carried by a diaphragm 21 to isolate one side of
engine.
The gas-turbine engine comprises a compres
the fuel delivery pipe IOA by the plungers riding
down the cam face of the swash plate I I against
the action of the springs 10.
the valve from the other.
As will be seen, one
side of the valve 25 is subjected to the delivery
pressure of pump I 6 and the other side is in
communication through a duct 28 with the down
The means illustrated to control the delivery of
fuel to the engine by varying the angle of inclina 55 stream side of the orifice I8.
The valve 25 will open when a predetermined
tion of the cam face of the swash plate i! is in
pressure drop is reached across orifice I8 and
part the subject of our co-pending U. S. appli
ensures that the pressure applied to the piston
cation Serial No. 26,424, filed May 1l, 1948, now
I3 has a selected minimum value depending on
Patent No. 2,618,222 issued November 18, 1952.
ln the arrangement of Figure l, the angle of 60 the rate of the spring 26. This ensures that the
stroke of the pump I0 cannot increase above a
inclination of the fuel pump swash plate II is
selected value and that over-fuellingr is avoided.
varied by means of a piston and cylinder device
The spring 28 is preferably selected to have a
whereof the piston I3 is slidable in the cylinder
rate such that the predetermined pressure drop
i4 against the action of a spring I5, it being
arranged that as the spring I5 is compressed the 65 at which the valve 25 opens is substantially un
affected by the rate of fiow of liquid in the con
pump stroke decreases.
trol
circuit, so that the valve does not introduce
Hydraulic control means is provided to dis
a variable pressure drop when liquid is flowing
place the piston I3.
through it.
The control means comprises a constant dis
A second lift valve 29 is provided to limit the
70
placement pump IS, for instance a gear pump,
maximum
pressure drop. This valve is loaded by
arranged to be driven at a speed proportional
a spring 30 and is carried by a diaphragm 3I.
to the engine speed through a drive indicated at
The valve 29 is connected hydraulically in par
l2 (Figure 1A) and drawing liquid from a reser
allel with the valve 25 and the orifice I8 to control
voir l? and delivering it through an orifice I 8
the flow through a pipe-line 32. This valve is
back to the reservoir. The effective area of the 75
85m Ill'
6.
loaded: on. one: side by' the delivery.'l pressure. of.’l
pump, I6. andg its: other side is~ in communication
fuel. deliveries. at. ground level due to thel control
of valves 2.5, 2.9; and Fumar) andv Flocmn). the max;
through4 duct 28 with the. downstream side ofthe
orifice. I8. The valve is'y therefore. in the nature
imumand-:minimum permitted> fuel. deliveries at
high altitude: (say 4.0;000 feet): due to the. control
of a. relief' valve and' opens when a preselected
pressure. drop is reached. across orifice i8. thereby
of valves.' 25, 2.9 and capsule 34.. The engine fuel
requirement curves. at> ground level is the4 line
GLI'ID‘ and that' aty the specified' altitude is the
line ALT(.40)&.. It‘will` be clear that` the> rates' of
springs 26, 3.0 and. capsule 34 will be selected so
that theY lines. Forma), Fmi/nn). and Flnmaxi,
limiting the. extent tov which the. stroke. of pump
ID. can. be decreased. In this way under-fuelling
of the. engine. is avoided..
It is also arranged' that-the maximum andimin
imum pressure drops. that can be: applied to the
Homin). will' lie one` on each side of the curves
piston I3 are varied with variations in the alti
tude at` which the engine is operating. For this
purpose means.. responsive to the ambient atmos...
pheric. pressure. is;v provided to- vary the. load on
the. valves; 2 5', 2 S". This: means in. the4 arrangement
GLM) and-- ALTMU). respectively.
Curves F1, F2, F3, F4 are fuel delivery curves at
different orifice settings and the engine speed will
be stabilised for a given oriñce setting ati a speed.
corresponding to the point of. intersection of' the
fuel-delivery curve. appropriate. to. the orifice set
tingl and the. appropriate altitude consumption
illustrated comprises an evacuated capsule,` 34
located' between. the» valves.: 25, 29 which are.
arranged’ to open in. opposite directions; in. a
curvay
chamber 35 which is: open to. atmosphere or com 20
municates with the enginev compressor air; intake.
The capsule 3c> is arranged to. loadV the. valves
through push-rodsv 3B'. Clearlyy on increaseV of
altitude, the capsule. expands. and increases.. the
load on the valves, and on decrease of altitude
the valve loading is decreased. In. the result, the
maximum and minimum stroke settings of. the
fuel-pump Iill are less at altitude than'> those at'
ground level.
The capsule 34 can be, if' desired, replaced by
two capsules onev for each of thevalves' 25, 29.
The capsule or capsules will be selected to have
a ratev giving the desired valve-load/altitude
characteristics in accordance with the engine; fuel
requirements with change. ofy altitude.
The operation. of theA control above described
Thepresent invention provides means for vary
ing the. fuel delivery in accordance with changes
in> ambient atmospheric pressure and also if de
sired' for varying the effect. of the ambient pres
sure control in. accordance with the engine rota
tional speed or the fuel delivery to the engine.
In .applying the invention to the control as
above described means responsive to changes of
ambient atmospheric pressure is associated with
the. valve control orifice I8 to Vary the pressure
drop 'acrossl the orifice I8r for any given setting
thereof so' that the fuel delivery of the pump Ill
is varied in accordance with ambient atmos
pheric pressure.. This barometric pressure re
sponsive means comprises evacuated capsule 31
o located and anchored at` one end toa chamber
38 open to atmosphere or to the engine com
is illustrated in the graphs of Figures 2 and 3.
pressor air intake. The-capsule is arranged by itsl
Referring> to Figure2, there- is shown curves giv
expansion and contraction under variations in
ingY the pressure drop applied to the` piston. I3
plotted against' engine. speed N. The pressure 40 the ambient pressure to operate a valve 39 con
trolling the flow.l of liquid through a by-pass 46
drop curves PD1, PD2, PDs, P134 correspond' to
around the oriñce I8 from the upstream side to
differentsettingsof orifice I8, P-Dl corresponding
the downstream side thereofy so that the pressure
to the idling speed selection by- lever 20', PD4r to
drop appliedi tothe piston I3 increases with alti
maximum speed, PD2 and PD3 to intermediate
tud'e. The restriction` afforded by the capsule
settings. The line- “Full Stroke.” indicates the
controlled valve 39 can be arranged so that for
minimum pressure required just to- displace the
any
desired setting ofthe control. lever, the speed
piston I3l from the full-stroke setting of the fuel
of the engine is independent of altitude.
pump and the line “Zero Stroke” indicates the
The operation of the device will be clear from
pressure drop required to move the piston I3
a consideration of Figure 4. F5 is the fuel-deliv
fully to the minimumy stroke setting of the fuel
eryy curve: for a selected setting of orifice IB and
pump.
Gl3(0) and' ALTMIJ) are the engine requirement
The effect of valve 25 and capsule 3'4 is illus
curvesïat‘. groundî level. and at altitude (e. g. 40,000
trat'ed by lines Pmi/cm and' Picci/cn) showing that
ft).
In the absence. of thek barometric control',
at'. ground level (indicated by suflixi'o) the mini'
for the selected oriñce setting the engine speed
mum pressure that can be applied to the valve
would stabilize. at a speed corresponding tothe
piston I3 is, given by the line Femm) andy at alti'
point X, i. e. the. point of intersection of the
tude (say 40,0130 feet, indicated by suffix 40) by
curves
Fs and GMG) and if now the aircraft
the line Pico/nay. Thus the maximum permissible
climbs. to an altitude corresponding to curve
stroke of the pump I0 dueto the governor at.
ALTMQ), the. engine speed will increase and sta
altitude is> less` than that at. ground level', and 60 bilize
at a speed corresponding to point Y. The
that both are less than the maximum possible
barometric control however ensures that. the
stroke. of’ the pump, thereby avoiding' over-fuel
speedV remainsv unaltered byl displacing the.- curve
ling..
Fctothe‘left so thatat each altitude.- the curvelïis.
They correspondingl curves'for valve 2.9- and capiintersects’ the. appropriate consumption. curve; on
sule. 34. are the lines: Pmmxr andY Proovitx), showing
thez line». XZ’. which represents a constant engine
that the minimum4 permissible strokeof'pump Iûï,
speed;.
is> less- at. altitude: than at“ ground level, and that
In certain casess it maybedesired tc= cause. the
both are greater than> the minimum possible
capsuley to-have a. greater or less effect' at differ
stroke thereby avoiding underfuelling.
ent- engine.l speeds, so that, for instance, at lour
The corresponding fuel delivery engine. speed 70 engineî speeds, e; g.A at idlingspeeds, for a given
curves; are given in Figure 3; In this'4 graph, the
setting; of the: orifice: Itr they engine. speed.: in
line “Fullf‘ Stroke”- indicates the maximum possi’
creases: with. altitude, while at higher engine
ble fuel- delivery andï the line “Zero Stroke” the
speeds the. engine speed does. not change with
minimum possible fuel delivery, Fmr/:exi and
altitude fora given. oriíìoe setting.
Femm): the maximum` and minimum permitted 75 For this.r purpose. an arrangement. as. illustrated
2,664,152
in Figure 6 may be employed. In this arrange-1
ment the bypass 40 includes a second needle valve
42 which is controlled by a piston -43 Working in
a. cylinder 44 against a spring 45. The piston is
controlled by the pressure drop across a restric
tion oriñce ¿E in the fuel pipeline to the injection
devices I2 and the spring strength is selected so
that at fuel flows above that represented by the
line Fa (Figure 5) the spring is fully compressed
nelly-operable speed-selecting member, a second
conduit connected with said ñrst conduit at
points upstream and downstream of said ñrst
oriñce, a second valve member projecting into
said second conduit to restrict the flow there
through, a lever for varying the extent to which
said second valve member restricts the ñow
through said second conduit, a fulcrum for said
lever, a capsule arranged to be responsive to
changes in ambient atmospheric pressure and
and the valve 42 acts as a ñxed restriction. When 10 connected with said lever to rock the lever about
the fuel flow decreases to a value below that rep
resented by the line Fs the valve 42 opens re
its fulcrum in a manner to increase the restric
tion afforded by said second valve member on
ducing the effective restriction by the oriñce I8
decrease of the ambient atmospheric pressure, a
thereby giving an increased fuel flow for the
ñxed area oriñce connected in said first conduit
oriilce setting.
upstream of the points of connection of said sec
Thus, when the orifice is set, for example, for
ond conduit with said ñrst conduit, a piston and
idling, the engine speed at ground level will be
cylinder device whereof the cylinder is connected
given by the point No (idling) and at altitude by
at its ends to said ñrst conduit at points upstream
the point N40 (idling) obtained by displacing the
and downstream of the ñxed area oriñce respec
20
curve F7 to the right to a position Fe, which is
tively, a spring loading said piston on the side
equivalent to increasing the effective area of
thereof connected with the first said conduit
orifice I8.
downstream of the ñxed area oriiice, said piston
Another arrangement for the same purpose is
being connected with the fulcrum so that the
illustrated in Figure '7. In this arrangement, the
fulcrum moves with the piston and that on in
25
capsule 37 is connected to needle valve 3S through
crease of engine speed the fulcrum is moved to
a lever 52 which has a variable fulcrum 41. ‘The
position of the fulcrum 41 is determined by a
piston 48 working in a cylinder 49 against a
spring 59. The piston 48 is displaced by the pres
increase the effect of the capsule on the second
valve member; and a pressure-responsive device
having pressure connections to said ñrst conduit
upstream and downstream of said first flow-re
sure drop across a fixed oriñce 5I which is prei 30 stricting oriñce thereby to respond to the total
erably located immediately downstream of the
pressure drop across said flow-restricting means
governor pump I6. The position of the piston 48
and connected to said adjusting means to actu
is thus dependent on the speed of the engine.
ate it.
In operation, as the engine speed is increased
2. In a gas-turbine engine fuel-system includ
the piston will travel to the left thereby moving
ing adjusting means to vary the delivery of fuel
the fulcrum 41 to increase the effect o1" the cap
to the engine, control means to actuate the ad
sule 31 on the needle valve 39. Thus at low
justing means comprising a constant displace
speeds, the capsule will have less eil‘ect on the
ment hydraulic pump adapted to be driven at a
setting of the needle valve 3S than at high en
speed proportional to engine speed; dow-restrict
gine speeds, so that the altitude correction due to 40 ing means connected to said hydraulic pump to
the constriction aiîorded by valve 39 in conduit
receive the full delivery of said hydraulic pump
40 at low speeds is less than that at high speeds
and comprising a first conduit, a first orifice in
and a rise of engine speed with low speed settings
said conduit, a valve member co-operating with
of the orifice I8 is obtained on increase of alti
Said oriñce, a manually-operable engine-speed
tude.
selecting device to adjust said valve member' with
Although in the embodiment illustrated the
respect to said first oriñce to vary the area of
variable oriñce comprises a simple tapered needle,
the said oriñce, a second conduit connected with
it may be desirable to use variable restricting
said ñrst conduit at points upstream and down
means as described in our co-pending British
stream of said ñrst oriñce, a second valve mem
patent application No. 12,822/47, now British 50 ber arranged to restrict the ilow through said
Patent No. 639,262, issued June 28, 1950. In the
second conduit, a capsule arranged to be respon
speciñcation accompanying this application we
sive to ambient atmospheric pressure and con
have described variable restricting means com
nected with said second valve member to adjust
prising a combination of a variably loaded valve
it in a sense to increase the restriction afforded
hydraulically in series with a restricting orifice,
by it with decrease of ambient atmospheric pres
the load on the valve and the effective area of the
sure, a third valve member arranged to aiîord
orifice being simultaneously varied by the power
a restriction in said second conduit and means
setting device in Such a manner as to denne run
responsive to the actual fuel flow to the engine
up ranges appropriate for the various running
60 to adjust said third valve member to decrease
conditions of the engine.
the restriction afforded by it with decrease of fuel
We claim:
flow; and a pressure-responsive device hydrauli
l. In a gas-turbine engine fuel-system includ
cally connected to respond to the total pressure
ing adjusting means to vary -the delivery of fuel
drop across said flow-restricting means and ar
to the engine, control means to actuate the ad
ranged by its response to changes in the pressure
65
justing means comprising a constant displace
drop to actuate said adjusting means.
ment hydraulic pump adapted to be driven at a
3. In a gas-turbine engine fuel system includ
speed proportional to engine speed; a iirst con
ing adjusting means to vary the delivery of fuel
duit connected to said hydraulic pump to receive
to the engine, control means to actuate the ad
the full delivery of said hydraulic pump, a ñrst
justing means comprising e. constant-displace
flow-restricting orifice located in the nrst con 70 ment hydraulic pump adapted to be driven at a
duit, a valve member co-operating with said ori
speed proportional to engine speed; a manually
ñce, a manually-operable speed-selecting mem
ber adapted to adjust said valve member with
operable speed-selecting lever; conduit means
connected to Said hydraulic pump to receive the
respect to the first orifice whereby the area of
full delivery of said hydraulic pump and now
75
said first orifice is controlled solely by said man
2,664,152
restricting means located in said conduit means
and comprising a ñrst variable-area orifice the
area or" which is adapted to be controlled solely
by said manually-operable speed-selecting lever,
and a second variable-area orifice; pressure-re
sponsive means adapted to be responsive to
changes in ambient atmospheric pressure and
connected to vary the effective area of said sec
ond variable-area orifice in a manner to decrease
the area on decrease of ambient atmospheric
pressure, and a pressure-responsive device having
pressure connections to said conduit upstream
and downstream of said flow-restricting means,
thereby to respond to the total pressure drop
across said now-restricting means, and connected
to said adjusting means to actuate it.
4. In a gas-turbine engine fuel system includ
ing adjusting means to vary the delivery of fuel to
the engine, control means to actuate the adjust
ing means comprising a constant-displacement 20
hydraulic pump adapted to be driven at a speed
proportional to engine speed, a manually-opera
ble speed-selecting lever; a first conduit con
nected to said hydraulic pump to receive the full
delivery of said hydraulic pump, a first variable 25
area orince located in said conduit means and
adapted to have its area controlled solely by
10
area orifice in a manner to decrease the area on
decrease of ambient atmospheric pressure; and
a pressure-responsive device having pressure con
nections to said conduit upstream and down
stream of said flow-restricting means, thereby to
respond to the total pressure drop across said
flow-restricting means, and connected to said ad
justing means to actuate it.
6. In a gas-turbine engine fuel system includ
ing adjusting means to vary the delivery of fuel
to the engine, control means to actuate the ad
justing means comprising a constant-displace
ment hydraulic pump adapted to be driven at a
speed proportional to engine speed, a manually
operable speed-selecting lever; a conduit con
nected to said hydraulic pump to receive the full
delivery of said hydraulic pump, a first variable
area oriñce located in said conduit, the area of
said first variable-area orifice being adapted to
be controlled solely by said manually-operable
speed-selecting lever, a valve member arranged
to afford a restriction to fiow through said con
duit, a barometric capsule adapted to be respon
sive to ambient atmospheric pressure, a lever
linking said valve member and said capsule, an
adjustable fulcrum for said lever arranged so that
on decrease of the ambient atmospheric pressure
speed-selecting movements of said manually-op
the restriction afforded by said valve member is
erable speed-selecting lever, a second conduit
increased, and means adapted to be responsive to
connected by its ends to said first conduit on each 30 engine speed 'to adjust the position of said ad
side of said first variable-area orifice, and a
justable fulcrum to increase the effect of said
second variable-area orifice located in said sec
capsule on the valve member on increase of en
ond conduit; pressure-responsive means adapted
gine speed; and a pressure-responsive device hav
to be responsive to changes in ambient atmos
ing pressure connections to said conduit up
pheric pressure and connected to vary the effec 35 stream and downstream of said dow-restricting
tive area of said second variable-area orifice in a
oriñces, thereby to respond to the total pressure
manner to decrease the area on decrease of am
drop across said flow-restricting orifices, and
bient atmospheric pressure; and a pressure-re
connected to said adjusting means to actuate it.
sponsive device having pressure connections to
7. Control means according to claim 6, wherein
said conduits upstream and downstream of said 40 said means responsive to engine speed comprises
now-restricting orifices, thereby to respond to the
a fixed area now-restricting means connected to
total pressure drop across said flow-restricting
receive the full delivery of said hydraulic pump,
orifices, and connected to said adjusting means
and a spring-loaded piston connected to be loaded
to actuate it.
differentially by the pressures upstream and
5. In a gas-turbine engine fuel system includ
downstream of said fixed area now-restricting
ing adjusting means to vary the delivery of fuel
means thereby to be displaced by variations in
to the engine, control means to actuate the ad
the engine speed, and wherein the lever fulcrum
justing means comprising a. constant-displace
is connected to the piston to be displaced thereby.
KENNETH ROY DAVIES.
speed proportional to engine speed; a manually 50
KARL HERBSTRITT.
operable speed-selecting lever; conduit means
connected to said hydraulic pump to receive the
References Cited in the file of this patent
full delivery of said hydraulic pump and flow
UNITED STATES PATENTS
ment hydraulic pump adapted to be driven at a
restricting means located in said conduit means
and comprising a first variable-area orifice the 55 Number
1,381,512
area of which is adapted to be controlled solely
by said manually-operable speed-selecting lever,
and a second variable-area orifice connected in
said conduit means hydraulically in series with
said first variable-area orifice; pressure-respon 60
sive means adapted to be responsive to changes
in ambient atmospheric pressure and connected
to vary the effective area of said second variable
2,219,994
2,384,282
2,405,888
2,445,113
2,457,595
2,481,334
2,514,674
2,545,703
Name
Date
Smith ___________ __ June 14, 1921
Jung _____________ __ Oct. 29,
Chandler _________ __ Sept. 4,
Holley ___________ __ Aug. 13,
Green et a1 _______ -_ July 13,
Orr ______________ __ Dec. 28,
Nicolls ___________ -_ Sept. 6,
Schorn ___________ __ July 11,
Orr _____________ -_ Mar. 20,
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