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Патент USA US2403917

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July 16, 1946.
w. H. @ILLE
2,403,917
CONTROL APPARATUS
Filed April 20, 1942
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5 Sheets-Sheet 1
July 169 1946.
w. H. GILLE
2,403,917
CONTROL APPARATUS
Filed April zo, 1942
ANO
POWER
UN\T
s sheets-sheet 2
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July 16, 194:6o
w. H. GILLE
2,403,917
CONTROL APPARATUS
Filed April 2o„ 1942
s sheets-sheet a
§15. ê
Patented July 16, 1946
2,403,917
_UNITED STATES PATENT OFFICE
2,403,917 '
n
CONTROL APPARATUS
Willis H. Gille, St. Paul, Minn., assignor to Min
neapolis-Honeywell Regulator Company, Min
neapolis, Minn., a corporation of Delaware
Application _April 20, 1942, Serial No. 439,673
19 Claims. (Cl. 23.6-1)
2
The present invention relates to temperature
control systems, and more particularly to tem
Another object of the present invention is to
provide a system for controlling the temperature
perature control systems for use on aircraft.
The construction of a satifactory temperature
control system for use on aircraft presents many
its walls are quite thin, and it is subjected to
rapid variations in outside temperature. If an
even temperature is to be maintained within the
of an aircraft cabin. A further object is to pro
vide, in such a control system, means for regulat
ing the fuel supply to a heater.
Another object of the present invention is to
-provide an improved system for regulating the
temperature of an aircraft engine.
Other objects and advantages of the present
invention will become apparent from a considera
aircraft, it is therefore necessary that a tempera
ture responsive element be employed which re
tion of the appended specification, claims, and
drawings, in which
sponds- rapidly to changes in temperature.
Figure 1 represents a, plan view of a section of
an aircraft, showing the installation of a cabin
unusual problems. For example, the space whose
temperature is to be controlled is relatively small,
Furthermore, it is necessary that the system con
trolled by the temperature responsive element 15 temperature control system embodying my inven
also be capable of quick response. The required
tion in a somewhat diagrammatic manner,
rapidity of response must be much greater than
Figure 2 is a 'circuit diagram showing in greater
that required in buildings and vehicles operated
detail the connections of the bridge, ampliñer,
on the ground, because the temperature changes
motor and power supply units used in the system
encountered are much more rapid.
20 disclosed in Figure 1,
In addition to the requirement of high sensi
Figure 3 shows, somewhat diagrammatically,
tivity, a practical temperature control system for
the application of vmy invention to a different
type of aircraft cabin temperature control sys
use on aircraft must be insensitive to the changes
in barometric pressure which occur with changes
tem.
in altitude. It must also be insensitive to vibra 25 Figure 4 illustrates somewhat diagrammatlcally
tion, both of the high frequency type sometimes
the application of my invention to an aircraft
resulting from the operation 0f the aircraft
engine temperature control system employing a
engine, and the rough irregular bouncing en
hydraulic servo-motor.
countered in rough air conditions. An aircraft
Figure 5 shows a modified form of- hydraulic
temperature control system must also be light in 30 motor which may be utilized in the system shown
Weight and must produce no objectionable radio in Figure 4,and
interference.
Figure 6 shows a diiïerent embodiment of my
It is therefore an object of the present inven
invention as applied to an aircraft engine tem
tion to -provide an improved temperature control
perature control system.
system for use on aircraft. A further object of
Referring to Figure 1, there is shown a plan
the present invention is to provide a tempera
View of a portion of an airplane. The view is
ture control system which shall be very sensitive
taken looking downward at the floor of a com
to temperature changes, While remaining insensi
tive to atmospheric pressure changes and to
vibration.
`
Another object of the present invention is to
provide an aircraft temperature control system
which is light in weight and which does not pro~
duce objectionable radio interference.
Another object is to construct an automatic
temperature control system which may be readily
installed on existing aircraft to operate existing
temperature changes devices of various types
which are at present usually controlled manually.
A further object of the present invention is
to provide an improved electrical control system
for a hydraulic servo-motor. A still further ob
ject is to provide an improved control system for
a rotary electrical motor adapted to operate
valves controlling a hydraulic motor.
panionway I0 between a passenger cabin II and .
a. Vpilot’s compartment (not shown). A wall I2,
40 provided with a suitable door I3, separates the
companionway from the passenger cabin. Walls
I4 and I5 at the sides of the companionway I0
separate the latter from spaces IB and Il, which
may, for example, be used for cargo or baggage.
Portions of the floor are shown in the drawings as
broken away in order to better illustrate the tem
perature control systems, of which the chief parts
are mounted under the floor.
An air intake duct 20, which may be connected
with a suitable air intake (not shown) near the
front of the plane, is divided by a wall 2 I, into a
pair of parallel ducts 22 and 23. Air flowing
through the duct 23 passes over a radiator 24,`
which may be supplied with a. suitable heating
56 fluid, for example steam, through supply and re
3
2,403,917
turn pipes 25 and 2l. The duct 22 is provided
to by-pass fresh air around the heater 24. The
parallel ducts 22 and 2l rejoin each other at 21
and are connected to a suitable distributing duct
2l in the cabin Il.
,
'I'he relative amounts of air passing through
the ducts 22 and 2l are controlled by a set of
mixing dampers 30, suitably attached to an op
4
.
The ratio of the controlling effects ci' theseîre
sistances on the unbalance of the bridge was
therefore about twenty to one. -This ratio may
vary considerably in particular installations, and
the ratio between the resistance of the cabin tem
perature responsive element and that of the dis
charge temperature responsive element may be
different than the ratio between the resistance
erating bar 3|. The bar 3| is attached to a crank
of the cabin temperature responsive element and ,
arm 32 driven by a motor mechanism 33. The 10 that of the outside temperature compensating
motor mechanism 33 includes a split-phase motor
element. It has been found, however, that the
I4, and a gear train (not shown).
ratio should be at least ten to one in any case,
The split-phase motor 34 includes a pair of
and may be as high as fifty to one.
windings 35 and 35, which are spaced 90 electrical
'I'he bridge circuit 54 is provided with output
degrees apart. in accordance with the conven 15 terminals B5 and 61 connected to the input ter
tional construction of such motors. A condenser
minals 42 and 43 of the amplifier and power unit
31 is connected in parallel with winding 36. The
4|, respectively.
_
common terminal oi' windings 35 and 38 is
The bridge circuit 54 also includes a rebalanc
grounded as at 4I.
` lng potentiometer generally indicated at 10, hav
The capacitance of condenser 31 and the in 20 ing a slide wire resistance 1| and a slider 12 co
ductance of winding 3l are so proportioned that
operating therewith. Slider 12 is connected to
the two form a series resonant loop circuit. This
the bridge circuit through a conductor 13, while
loop circuit is supplied with energy by trans
the end terminals of slide wire 1| are connected
former action from winding 35, but the current
to the bridge circuit 54 through conductors 14
flow in winding 36 caused by this transformer 25 and 15.
action- is not sumcient, or of the proper phase
Referring now to Figure 2, it will be seen that
relationship, to cause rotation of motor 34. When
the upper left arm of bridge circuit 54 connects
a slight additional amount of energy is supplied
input terminal 52 with output terminal 4G and
to winding J8, however, it is energized sufficiently
includes a manually adjustable resistance 80, con»
to start rotation of motor I4 in a direction de 30 ductor 51, temperature responsive resistance elc
termined by the phase of the energy supplied by
ment 55, and conductor 5B. The upper right arm
the amplifier.
'
of bridge circuit 54 -connects output terminal $0
Motor 34 is supplied with electrical energy from
with input terminal 53 and includes a conductor
an amplifier and power unit generally indicated
5|, a ñxed resistance 82, and a conductor 83.
at 4|. This unit has input terminals 42 and 43 35 The
lower left arm of bridge circuit 54 connects
and output terminals 44 and 45. Power is sup
input
terminal 52 and the slider 12, and includes
plied to the amplifier and power unit 4| from a
battery 46 through power supply terminals 41
a conductor B4, a fixed resistance 85. conductor
14, and that part of slide wire 1| between its
and 48. The amplifier and power unit 4| also
left hand terminal and the slider 12. The lower
has terminals 50 and 5| through which electrical 40 right hand arm of bridge circuit 54 connects
energy is conducted to input terminals 52 and 53
slider 12 and input terminal 53, and includes
of a bridge circuit generally _ndicated at 54.
that portion of slide wire 1| between slider 12
The bridge circuit 54 includes a first tempera
and
its right hand terminal,l conductor 15, a fixed
ture responsive element 55. which may be an
resistance 86, and temperature responsive re
electrical resistance element having an appre 45 sistance
elements 60 and 63.
ciable temperature coefncient of resistance. The
A variable resistance 81 is connected in parallel
resistance element 55 is shown diagrammatically
with slide wire 1|. The function of resistance
in Figure l, and may be mounted on the wall I2.
81 is to determine the amount of movement of
'I'he particular form oi' the temperature respon
slider 12 required to correct a given unbalance
sive resistance element and the means for mount
of the bridge circuit 54.
ing it on the wall |2 may preferably be as de
The function of adjustable resistance 80 is to
scribed in the copending application of Russell
determine the value of temperature adjacent the
H. Whempner, Serial No. 439,679, dated April
resistance 55 at which the bridge 54 will be bal
20, 1942. The resistance element 55 is connected
to bridge circuit 54 by a'Dair of conductors 55 55 anced. In other words, it operates to set the
control point of the system.
and 51.
'
The amplifier and power unit 4| includes an
A second temperature responsive resistance ele
amplifier generally indicated at 90, which may be
ment 00 is mounted in the discharge duct 28 and
of any type well known in the art in which the
is connected to the bridge circuit 54 by means
of conductors 6I and 52. A third temperature 60 phase of the output voltage is reversible with a
reversal of the phase of the input voltage. A typi
responsive resistance element 63 is mounted in
cal amplifier of this type is shown in the Beers
the intake duct 20 and is connected to bridge
circuit 54 by means of conductors 54 and 55.
Patent 2,020,275. Another desirable type of am
It has been found desirable that the tempera
plifler for this purpose is one of the type disclosed
ture responsive element 55 should have the larg 65 in Figure 1 of the copending application of Al
est eifect on the system, while the elements 50
bert P. Upton, Serial No. 437,561, dated April 3,
and 53 should have smaller effects. The ratio
1942. Amplifier 90 has input terminals 42 and
between the effects of these ele’nents on the sys
43 and output terminals 9| and 92. Bridge out
tem may be controlled by properly designing their
relative resistances. For example, in one system
built in accordance with the present invention,
the cabin temperature responsive element had
a resistance of 500 ohms at 70° F., while the
compensating resistance elements had a resist
ance of about 25 ohms at the same temperature. 75
put terminal 6B is connected to amplifier input
terminal 42 by a conductor B8. Bridge output
terminal 61 is connected lto amplifier input termi
nal 42 by a conductor 69. Input terminal 43 is
grounded at 93, and also serves as an output ter
minal of the amplifier 90. It will be readily un
derstood that the conductor 69 may be omitted,
„ 2,403,911
" ì
5
6
\ and bridge output terminal 61 connected to
open, and the slider 12 is at'the mid-point of slide
ground instead.
wire 1|. Let it be assumed that the bridge 54 is
While the amplifier referred to in the above
balanced, and that the adjustable resistance 80
mentioned Upton application is one which has
has been set so that the bridge remains balanced
been found to be particularly desirable for use
when the temperature in the cabin || is 70°.
in the present apparatus, it is possible to employ
When the bridge circuit 54 is balanced, the
any amplifier capable of supplying at the output
output terminals 66 and 61 are at the same po
terminals a voltage which reverses in phase with
tential, so that no signal is applied to the input
reversal of the phase of the out-put voltage of
terminals of amplifier 90. Under these condi
the bridge. Such amplifiers are well known in 10 tions, no alternating current flows through wind
the prior art. It is accordingly not considered
ing 36 of motor 34. Although winding 35 of
necessary to completely illustrate the details
motor 34 is continuously energized by its connec
thereof. However in order to facilitate an under
tions to transformer secondary |02, both wind
standing of the general operation of the ampli
ings 35 and 36 must be energized with currents
fier, the final amplifier stage is indicated in the 15 of the proper phase relationship in order to cause
drawing. This stage is provided by a double tri
rotation of motor 34, in accordance with the well
ode tube 90a having two anodes 90b and 90e. A
known characteristics of split phase motors.
double cathode 9 la is associated with «both anodes
Condenser ||5 is connected in series with motor
90b and 90C. Associated with anode 90b is a
winding 35 in order to shift the phase of the cur
grid 92h and with anode 90e is a grid 92e. 'I'he 20 rent supplied to that winding approximately 90
cathode Sla is connected by a lead 91 to the in
electrical degrees with respect to the potential
put terminal 43 which in turn is connected to
and the terminals of transformer secondary
ground 93 as previously noted. 'I'he two grids
winding |02.
`
92h and 92e are connected together. The junc
When the bridge circuit 54 is balanced, the
tion of the connection to these two grids is indi 25 output terminals 66 and 61 are at the same
cated by the reference numeral 94a. This junc
potential, which is _at some value intermediate
tion is shown as being connected by a dotted line
the potentials of input terminals 52 and 53. If,
connection 95a to the input terminal 42. This
after the bridge is balanced, the resistance of
connection is shown in dotted lines because in
element 55 ldecreases, the potential of output
actual practice two or more stages of amplifica 30 terminal 66 assumes a new value closer to that
tion would be provided between the input termi
of input terminal 52. Since the output terminal
nals 42 and 43 and the grids 92h and 92o. As far
61 retains its original potential value, it will be
as the essential operation of the amplifier is con
seen that there is a potential difference between
cerned, however, it may be considered as though
output terminals 66 and 61. As between the two
grids 92h and 92e are directly connected to the
output terminals, the potential of output ter
input terminal 42 and that the cathode 96 is
minal 66 is closer to that of input terminal 52,
directly connected by conductor 91 to terminal
while the potential of output terminal 61 is
43 and hence to ground.
closer to that of input terminal 53. Therefore,
Power is supplied to amplifier '90, bridge circuit
the unbalance potential appearing between out
54, and motor 36 from battery 46 through an 40 put terminals 66 and 61 is in phase with the
inverter 94 which may be of the well known vi
potential supplied to input terminals 52 and 53.
brator type. Inverter 94 is connected to a pri
0n the other hand, if the resistance of element
mary winding 95 of a transformer 96 having sec
ondary windings |00, |01, |02 and |03.
Secondary winding |00 supplies power to ampli
fier 90 through conductors |01 and |08.
Secondary winding |0| supplies power to am
pliñer 90 and to winding 36 of motor 34. A con
55 increases after the bridge is balanced, the
potential of output terminal 66 assumes a value
closer to that of input terminal 53. The output
terminal 61 retains its original potential value,
and therefore a potential difference appears be
tween output terminals 66 and 61. In this case,
nection may be traced from the upper terminal
however, as between the two output terminals,
of transformer winding |0| through a conductor 50 the potential of terminal 66 is closer to that of
||0 to amplifier output terminal 9|. Another
input terminal 53, While the potential of terminal
connection may be traced from the lower termi
61 is closer to that of input terminal 52. There
nal of secondary winding |0| through a conduc
fore, it may be seen that the unbalance poten
tor || | to amplifier output terminal 92. A third
tial appearing between output terminals 66 and
connection may be traced from the midpoint of 55 61 is opposite in phase to that supplied to input _
secondary winding |0| through a conductor ||2,
terminals 52 and 53.
terminal 45, a conductor | I3, winding 36 and con
Consider now the effects upon the balance of
denser 31 in parallel, ground connection 40, and
the bridge circuit of changes in the resistance
ground connection 93 to amplifier terminal 43.
of elements 60 and 63. If, after the bridge is
Transformer secondary winding |02 supplies
balanced, the resistance of either element 60 ci
power t0 winding 35 of motor 34 through a cir
63 decreases, the output terminal 61 thereby
cuit which may be traced from the lower termi
assumes a potential closer to that of input ter
nal of winding |02 through a conductor ||4, a
minal 53. The potential of output terminal 66
condenser H5, a conductor ||6, terminal 44, a
retains its original value, so that, as between the
conductor | I1, winding 35, ground connection
two output terminals, the potential of terminal
40, a ground connection |20, and a conductor |2|
66 is closer to that of input terminal 52, while
to the upper terminal of secondary winding |02.
the potential of terminal 61 is closer to that of
Secondary winding |03 is connected to termi
output terminal 53. Therefore, the unbalance
potential appearing between output terminals 66
nals 50 and 5I, which are connected to input
and 61 is in phase with the potential supplied
terminals 52 and 53 of bridge 54 through con
to input terminals 52 and 53.
'
ductors |05 and |06 respectively.
On the other hand. if the resistance of either
Operation of Figures 1 and 2
-element 60 or 63 increases after the bridge is
When the parts are in the positions shown in
balanced. the output terminal 61 thereby assumes
the drawings, both sets of dampers 30 are half
a potential closer to that oi' input terminal 52.
2,408,917
7
The potential o! output terminal 8B retains its
that the voltages applied to these two grids are
identical and hence .in phase with each other.
The voltages applied to the two anodes llb and
original value, so that, as between the` two cut
put terminals, the potential of terminal EI is
closer to that of input terminals 53, while that
of terminal I1 is closer to that of input terminal
l2. Therefore, the imbalance potential appear
in! between output terminals .I and B1 is op
"c are out of phase with each other. As a re
sult, the amplifier signal voltage applied to the
grids B2b and 82e will be in phase with the> anode
voltage applied to either one or the other oi' the
posite in phase to that supplied to input ter
two anodes so that current will ilow through one
minals I2 and B3.
or the other of the two paths traced. The phase
Recapitulating, it will lbe seen that a decrease
of the signal volta-ge is dependent upon the phase
in the resistance oi' any of the elements il, SII
of the output voltage oi' the bridge which, as
or ß
cause an alternating potential to
previously explained, is dependent upon the di
appear at output terminals “and l1, which is
rection in which the bridge is unbalanced. Thus,
in 'phase with the potential supplied to input
one or the >other o_i' the two circuits traced is
terminals l2 and BI. 0n the other hand, an 15 rendered effective depending upon the unbalance
increase in resistance oi' any of the elements
oi the bridge. Since the voltages applied to these
Il, Il or Il will cause an alternating potential
" two circuits are 180° displaced in phase with
to appear at output terminals It and 61 which
respect to each other, it will be obvious that the
is opposite in phase to that of the potential
current ilowing through winding Il when the
supplied to input terminals l! and B3. '
20 bridge is unbalanced in one direction will be 180°
A rise in temperature either in the intake d-uct
displaced with respect to that ilowing through the
2l adjacent resistance element C3,l in the dis
same winding when the bridge is unbalanced in
charge duct 28 adjacent the resistance element
the opposite direction. Since the output voltage
Il, or in the cabin II itself adjacent resistance
of secondary III is in phase with the output voit
element I! indicates that less heat is necessary 25 age oi.' secondary IBI which supplies the input
to maintainthe cabin II at the desiredtemper
ature.
voltage to the bridge, it will be readily apparent
that the current ñowing in winding il will be oi
When such a rise in one of the three
temperatures referred to occurs, the resistance
of the corresponding one of the temperature re
sponsive elements t5, 6I and I3 increases, there
the same or opposite phase as the terminal volt
30
by unbalancing the bridge circuit 5l in such a
direction that an alternating potential appears.
at output terminals 88 and 61 having a phase'
opposite to that of the potential supplied to
terminals 52 and 53. On the other hand, when
a decrease in any of these temperatures occurs,
a need for the supply oi' additional heat to the
cabin II is indicated, and the bridge is uxr
balanced -in such a direction that a potential
appears between terminals 6B and 61 having the 40
same phase as the power supplied to input ter
minals I2 and B3.
Two possible circuits may be traced through
the motor neld winding 3i. One of these cir
cuits extends from the upper terminal of sec 45
ondary III through conductor III, terminal DI,
anode IIb. cathode sla, conductor 91, ground
connections 93 and l0, neld winding 3B, conductor
Ill, terminal l5 and conductor H2 to the center
tap o! secondary IIII. The other circuit extends
from the lower terminal of secondary Ill through
conductor III, terminal 92. anode 80c, cathode
lla, conductor l1, ground connections 93 and ll,
ileld winding Il, conductor III, terminal ll, and
conductor Il! to the center tap of secondary IIII.
Current will ilow through the iirst traced circuit
only during the half cycle in which the anode
IIb is positive with respect to the cathode. This
will occur only during the half cycle when the
upper end of the secondary IOI is positive with
respect to the lower. Current will i‘iow through
the last mentioned circuit, on` the other hand,
only when anode lic is positive with respect to
the cathode and hence the lower end of second
ary III is positive with respect to the upper end.
50
age of the secondary winding |02.
Since the current ilowing in winding Il is of
the same or opposite phase as the terminal volt
age of the transformer secondary winding, while
the current flowing in winding 35 is shifted 90
degrees in phase in respect to the terminal voltage
of the transformer secondary winding, motor Il
will be driven in one direction or the other de
pending upon whether the current in winding ll
is of the same or the opposite phase asthat of
the secondary terminal voltage.
The connections between the bridge circuit 5l
and the amplifier 90, and between amplifier 8l
and motor Il, are such that when the bridge is
unbalanced in a direction indicating the need
for less heat in the cabin II, motor 36 is driven
in a direction to close the dampers in the heater
duct 2l and open the dempers in the by-pass duct
22, thereby supplying less heat to the cabin II.
This operation of motor Il also drives slider 'l2
to the right along slide wire 'II, thereby rebalanc
ing the bridge circuit Il.
When the temperature adjacent either of the
three temperature controlling resistance elements
Il, Il and 83 decreases. the bridge is unbalanced
in such a direction that amplifier l0 responds to
drive motor I4 so as to close the dampers in by
pass duct 22 and open the dampers4 in heater
duct 2l, thereby supplying more heat to the
cabin II. This is done by driving lever arm 3|
and slider 'l2 to the left. Motion oi’ slider 'I2
to the leit rebalances the bridge circuit so as to
stop the motor Il.
It should be noted that in the amplifier and
power unit 4I, the only wound coils or electro
magnetic devices using iron cores are those asso
It is furthermore possible for
ciated with inverter 94, transformer 98, and mo
tor Il. The weight oi the amplifier and power
unit has thereby been maintained at a minimum.
current to ilow through either one of these cur
rent paths only when the eilect oi the amplifier
signal potential as applied to the grid is to tend
verter Il, which may be readily shielded so as
Thus It is possible only during alternating hall'
cycles for current to ilow through the respective 4
circuits traced.
to raise the potential of the grid during the halt
cycle in which the anode is positive. Since, as
was previously noted, the grids' B2b and 92e are
connected together. it will be readily apparent
Furthermore, there are no switch contacts in the
entire system, except those associated with in
to produce no radio interference.
,
Figure 3
In Figure 3 is disclosed an aircraft cabin tem
perature control system in which the control is
42,403,917
9
accomplished by modulating the fuel supply to a
10
,
.
As in Figure 1 the motor mechanism 33 modu
lated the position of the damper 30 in response
to temperature changes, so in Figure 3 the motor
mechanism 33 modulates the position of the valve
|22. It is believed that this operation of valve
|22 by motor mechanism 33 will be readily un
derstood from what has gone before, and need not
be further described.
ñuid fuel burning heater arrangement. In this
ligure, all parts of the system which correspond
exactly to similar parts in Figure 1 have been
given the identical reference numerals. It will
be noted that the bridge circuit 54, the ampliñer
and power unit 4|, the motor mechanism 33, are
the same asin Figure 1. Furthermore, the loca
tion of the temperature responsive resistance 63
As the valve |22 moves towards its closed 'posi- _
in the intake duct 20, the location of temperature 10 tion from the position shown, the cam |33 is ro..
responsive resistance 60 in the discharge duct 28,
tated in a counter-clockwise direction. The con
and the location of temperature responsive re
struction is such that when the valve |22 reaches
sistance 55 in the cabin I I are the same as the
its minimum position, the follower |32 of switch
location of the corresponding elements in Fig
arm |3| has nearly reached the end of the high
ure 1.
15 dwell portion of cam |33. Ii' the bridge circuit
In Figure 3, the air supplied to the cabin ||
54 then becomes unbalanced so as to indicate
passes through the intake duct 20, over a plu
a need for further reduction in the supply of fuel
rality of fluid fuel burning »heaters |20, and
to the heaters |20, cam |33 rotates a slight addi
through the discharge duct 28 to the cabin ||.
tional amount in a counter-clockwise direction.
Fuel is supplied to the heaters |20 through a fuel 20 This moves the high dwell portion out from under
supply pipe |2|. The supply of fuel to the heaters
follower |32, allowing it to drop to the low dwell
|20 is controlled by a modulating valve |22, and
portion, thereby opening switch |21. Opening
by a shut-off valve |23.' Any suitable source of
of switch |21 shuts out the supply of electrical
iluid fuel may be used. For example, in certain
energy to the operator |25 and to the» igniters
installations, the fuel has been a combustible ‘_ |26. Deenergization of operator |25 causes shut
oil' valve |23 to close.
It should therefore be apparent that the supply
The modulating valve |22 is operated by the
of fuel to the heaters |20 is modulated from a
motor mechanism 33. The valve |22 has an
maximum to a> minimum value and that if a fur
opening |24 in the center thereof to insure that 30 ther reduction in the supply of fuel is necessary,
it never fully closes, but always permits a mini
the supply is cut off completely and the igniters
mum flow of fuel therethrough.
are deenergized. In heaters using highly com
The shut olf valve» |23 is provided with an elec
bustible fuels of the type described, it is neces
tricai operator |25, which may be a solenoid or
sary that a minimum supply of fuel be maintained
a rotatory motor, for example. Each of the heat
in order to prevent a flash back, a phenomenon
ers |20 is provided with a suitable ignition mech
in which the flame moves back along the fuel
'anism such as the hot wire igniter shown some
supply pipe to the source of fuel. This minimum
what diagrammatically at |26. Energization of
supply is maintained by the system shown, until
the system is completely shut down.
valve operator |25 and the igniters |26 is con
trolled by a switch | 21 comprising a stationary 40
Figure 4
contact |30 and a movable switch arm |3|. The
mixture of gasoline and air drawn from the in
take manifold of one of the aircraft engines.
switch arm |3| carries a follower |32 of insulat
ing material, cooperating with a cam |33 driven
In Figure 4 is shown an engine temperature
control system embodying my invention. An air
by the motor mechanism 33.
craft engine |50, of the air cooled type. is pro
vided for driving a propeller |5|. The engine
Operation of Figure 3
|50 has a. cowl |52, of conventional form. Air
For purposes of clarity, the modulating valve
for cooling the engine |50 flows through an open
|22 has been shown in Figure 3 in its fully open
ing at the front of the engine, which is not shown
position. The slider 12 of rebalancing poten
in detail in the drawings, but Whose general
tiometer 10 is shown at its corresponding posi 50 location is shown at |53. After passing over the
tion at the upper extremity of slide wire 1|.
engine, the heated air passes out through nap
|54 in the cowl |52.
Likewise, the cam |33 is shown in a position
wherein it has closed switch |21, thereby com
A temperature responsive device |55 is mounted
pleting energizing circuits for shut-off valve op
on the engine |50. It may, for example, be con
erator |25 and igniters |26.
55 veniently attached to a spark plug |59. Resist
ance element |55 is connected in a. bridge circuit
The energizing circuit for operator |25 may be
generally indicated at |56, having input terminals
traced from the upper terminal of battery 46
|51 and |58, and output terminals |60 and |6|.
through a conductor |34, switch |21, a conductor
|35, a conductor |36, operator |25, and ground
Input terminals |51 and |58 are connected
connections |31 and |38 to the lower terminal 60 through conductors |62 and |63 into terminals 50
of battery 46. The energizing circuit for igniters '
|46 may be traced from the upper terminal of
battery46 through conductor |34, switch |21,
and 5| respectively of an amplifier and power
unit 4|, similar to the corresponding amplifier
and power unit shown in Figures l. 2, 3. Output
terminal |60 of bridge |56 is connected through
conductors I 35 and |40, and a plurality of parallel
conductors |4| to the respective igniters |26, 65 a conductor |64 to input terminal 42 of amplifier
only one of which is shown, the frame of burners ,
and power unit 4|. Output terminal |6| of bridge
|20, supply pipe |2|, and ground connections |42
|56 is grounded at |65, and is therefore connected
and |38 to the lower or grounded terminal of
through ground connections |65 and 03 to input
battery 46.
terminal 43 of amplifier and power unit 4|.
The construction of operator |25 is such that 70
The upper left hand arm of bridge circuit |56
when energized it maintains valve |23 in open
connects input terminal |51 with output terminal
position. Therefore, when the parts are in the
|60, and includes a conductor |66, resistance ele
position shown in the drawings, a maximum sup
ment |55, conductors |61 and |66, and' that por
‘ ply of fuel to the burners |20 is maintained, and
tion of a slide wire resistance |10, between its
the fuel is ignited by the igniters |26.
75 left hand terminal and its cooperating slider |1|,
2,403,917 ’
ll
which is electrically connected to output terminal
|00. Slide wire |10 and slider |1| constitute-a
rebalancing potentiometer |12, hereinafter re
ferred to as the ultimate rebalancing poten
tiometer.
attached to the piston rod 2|8, as at 220, are a
pair of links 22|, whose opposite ends are pivot
ally attached to the cowl ñaps |54. Another link
The upper right arm of bridge circuit |58 con
223 is attached at one endv to an intermediate
point on link 22| and at its opposite end to the
slider |1|. Either some portion of link 222 or a
nects output terminal |80 and input terminal |58,
and includes that portion of slide wire |10 be
tween slider |1| and its right hand terminal, a
suitable part of its pivotal connection with slider
|1| may .be made of insulating material in order
to prevent grounding oi! the slider |1|.
conductor |18, and a fixed resistance |14.
An 10
Operation of Figure 4
adjustable resistance |15 is connected in parallel
with slide wire |10 in order to determine the
amount oi movement oi' slider |1| necessary to
correct a given imbalance oi the bridge circuit
When the parts are in the position shown in
the drawing, the ilaps |54 are half-way open, and
the piston 2 I3 is in a central position in the cylin
I 58.
_
15 der 2| 2. The bridge circuit |58 is balanced, the
The lower left arm of bridge circuit |58 con
sliders |1| and |8| are in their center positions,
nects input terminal | 51 with output terminal I 8 I ,
and all the valves |9|, |92, |93 and |84 are closed.
and includes a conductor |18, a iixed resistance
Under
these conditions, let is be assumed that the
|11, and that part of a slide wire resistance |80
ytemperature
of the engine |50 increases, thereby
between its left hand terminal and its cooperat 20 increasing the resistance of sensitive element |55,
1118 slider |8|. Slide wire |80 and slider |8| i’orm
thus increasing the resistance between input ter
a rebalancing potentiometer hereinafter referred
minal |51 and output terminal |1| of bridge |58.
to as the proximate rebalancing potentiometer.
This unbalance of bridge circuit |56 causes a sig
The lower right arm of bridge circuit |58 con
nal to be impressed on the amplifier and power
nects output terminal |8| with input terminal 25 unit 4|, which in turn transmits a control im
|58 and includes that portion of slide wire |80
pulse to the motor mechanism 33. The connec
ybetween slider |8| and its right hand terminal,
tions are so arranged that the control impulse
a conductm' |88, a i'ixed resistance |84, and a
transmitted to motor 33 is in the proper direction
variable resistance |85. ’I‘he variable resistance
to cause it to rotate shaft |90 in a clockwise direc
|85 is provided in order to adjust the temperature
tion, and also to rotate shaft |88 in a clockwise
at which the control system maintains the engine
direction. Rotation oi shaft |88 clockwise causes
|50. A variable resistance |88 is connected in
movement
of slider |8| to the right along slide
parallel with slide wire |80 in order to determine
wire |80, thereby producing an increase in the
the amount of movement oi' slider |8| necessary
resistance between input terminal |51 and output
to correct a given unbalance of bridge |58.
35 terminal |8| to balance the increase between in~
Motor mechanism 88. which is controlled in
put terminal |51 and output terminal |80 caused
response to the unbalance potential of bridge |58
by the increase in engine temperature. This re
acting through amplifier and power unit 4|,
balancing of the bridge circuit |58 causes motor
drives, through a gear mechanism schematically
indicated at |81, a shaft |88 connected to slider (0
|8|, and a shaft |90 which carries a series of
cams |8|, |82, |98 and |84.
The cams |8|, |82, |88 and |84 operate a series
33 to stop substantially as soon as the valves are
opened.
-
/
Rotation of shaft |90 in a clockwise direction
causes opening of valves |95 and |91 under the
influence of cams ‘| 8| and |93. Valves |98 and
of four poppet valves |85, |88, |91 and |98, respec
tively. These poppet valves control the ilow of 45 |98 remain closed. High pressure ñuid is then
admitted to the right hand end of cylinder 2|2
high pressure iluid to a hydraulic servo motor
from inlet chamber 203 through valve |91, valve
280, of conventional design.
chamber
208, and conduit 2 |4. At the same time,
A suitable source o! high pressure iluid is pro
the pressure on the iluid in the left hand end of
vided for operating servo motor 200. this source
being shown in the drawing as a pump and high 50 cylinder 2| 2 is released through conduit 2 | 5, valve
chamber 205, valve |85. and outlet chamber 201.
pressure chamber associated therewith and num
'Therefore
a pressure differential is established
bered 20|. High pressure fluid may rlow from
between the opposite faces of piston 2|8, there
the high pressure chamber 28| through a suitable
by forcing it to the left from the position shown
conduit 282 to an inlet chamber 202 in a valve
casing 204, which contains the poppet valves |95, 55 in the drawings. Movement of piston 2|3 and
its associated piston rod 2|8 to the left causes
|88, |81 and |88. Valves | 88 and |81 control the
the links 22| and 222 to push the cowl ñaps |54
i'low of high pressure fluid from inlet chamber
further open, thereby causing an increased flow
288 to valve chambers 288 and 208, respectively.
of air over engine |50 to provide additional cool
Valves |85 and |88 control the iiow of iiuid from
ing thereof, so as to tend to restore its temper
valve chambers 205 and 208 to outlet chambers
ature to the value previously determined by the
201 and 208, respectively. Outlet chambers 201
setting of resistance |85.
and 208 are connected by conduits 209 and 2|0
Movement of piston rod 2|6 to the lei't is also
respectively, to a sump or receiver of low pressure
transmitted through links 22| and 223 to the
iiuid 2| |.
slider |1|. Movement of slider |1| to the left
The servo motor 208 comprises a cylinder 2|2
causes a decrease in the resistance between input
having a piston 2|8 reciprocatable therein. One
terminal |51 and output terminal |80. This
end of the cylinder 2|2 is connected through a
causes an unbalance of bridge circuit |58 in the
conduit 2|4 to the valve chamber 208, and the
other end oi' the cylinder 2 I2 is connected through
opposite direction from that caused by the pre
a conduit 2|5 to the valve chamber 205.
70 vious unbalance, so that a control impulse is
A piston rod 2|8 is attached tc the piston 2|8
transmitted to motor mechanism 33 causing it to
and passes through a suitable gland, not shown,
rotate shafts |88 and |90 in a counter-clockwise
in the end of cylinder 2|2, and through a bearing
direction. Rotation of `shaft |88 counter-clock
2|1, of any suitable construction, which may be
wise causes slider | 8| to be driven to the left
attached to a iixed part of the aircraft. Pivotally 75 across slide wire |80, thereby rebalancing the
2,403,917
13
bridge circuit, while rotation of shaft |90 in a
counter-clockwise direction causes closure of
valves I9| and |93, thereby stopping operation of
servo motor 200.
14
tion
to a certain
te to‘h
t" extent without causing the sys
m
‘m1,
.
I Figure 5
'
There is shown in Figure 5` a modified form of
'I‘he _resistance of slide wire |80 is made much
hydraulic servo motor which may be used in the
smaller than/the resistance of slide wire |10. Be
cause oi' this, the effect of potentiometer |12 on
system disclosed in Figure 4, and when used
the balance of the bridge circuit |50 is greater
therein results in a substantially different mode
than the effect of potentiometer |82. In other
of operation of the system. The servo motor 225
words, if the slider I1| moves through a given 10 of Fig. 5 comprises a. cylinder 226 and a loosely
ñtting piston 221 reciprocable therein. The other
portion of its range of travel, the slider |8| must
move through a greater portion of its range in
order to rebalance the bridge-circuit |55. There
fore, a small movement of slider |1| in response
to opening of the valves |9| and |93, for example, 15.
by their reference characters. It will be under
stood that a tightly iltting piston with a, leak
port or any similar' arrangement might be used.
is sufllcient to cause movement of slider |8| cor
so long as there is a small leak between the ends
parts are the same as in Figure 4, as indicated
\of the cylinder. The size of the leak as it ap
responding to the full closing movement of the
pears in Figure 5 has been exaggerated for the
valves.
sake of clarity. In practice, a very small orifice
Therelative effects of sliders |1| and |8| on
the balance of the bridge, and hence the amount 20 between the ends of the cylinder would be sum
cient.
of movement of slider |1| required to cause clo
When servo motor 225 is used in the system
sure of the valves, may be regulated by adjusting
the variable resistances |15 and |88.
‘
of Figure 4, the system is completely stable only
when the piston 221 is at a position determined
tentiometers |12 and |82 in the manner >de- 25 by the bias of the load on it. In the present case,
the ñaps |54, due to the balance between the out
scribed, fullopening and closure of the valves
side and inside air pressures acting on them,
may be controlled by very small unbalancing ef
always tend to return to a central position, which
fects in the bridge circuit. Full power is there
is approximately the position shown in the draw
by made available for control purposes even
ings. The load on the servo motor may therefore
through the correction required is small.
be said to bias it for movement to its center posi
It should be apparent that the rebalancing ac
By proportioning the relative effects of po
tion of the proximate rebalancing potentiometer „
|82 is only temporary, and that the slider |8| al- ways ñnally comes to rest at or near its center
tion.
When the servo motor 225 is used in the
system of Figure 4, and the bridge is balanced,
the piston 221 therefore moves slowly toward its
position. The ultimate rebalancing of the bridge 35 center position, the movement being controlled by
the flow of ñuid through the leak or orifice be
tween the ends of the cylinder 225. Therefore
plished by the slider |1| in accordance with the
the slider | 1| also moves slowly to its center
new position of cowl ilaps |54. When the bridge
position. During this movement the bridge cir
|58 is ultimately balanced the slider |8| is always
in or near its center position and all the valves> 40 cuit is maintained in balance by the rebalancing
action of slider | 8|, driven by motor 33.
|9|, |92, |93, and |94 are closed.
' When the rebalancing action required of slider
When the temperature of the sensitive resist
|8| carries it to a, point where one pair of valves
ance element |55 drops below the value which
begins to open, the servo motor piston -221 is
maintains the bridge circuit |55 balanced, a sig 45 given an impulse in the opposite direction away
nal of the opposite phase is applied to the ampli
from its center position. This of course causes
iler and power unit 4|, thereby causing rotation
slider |1| also to move away from its center posi
oi' motor mechanism 33 in the opposite direction
tion and unbalances the bridge in the opposite di
so as to rotate shafts |88 and |90 in a counter
rection so that motor mechanism 33 again closes
clockwise direction, thereby moving slider |8| to 50 the
valves which were opened. 'I'he net result is
the left and opening valves |92 and |94. It will
that the position of piston 221 tends to slowly
be readily understood that this causes movement
oscillate about a point such that the balance of
of piston 2|3 to the right, thereby movingvslider
the bridge is maintained with the slider |8| at
|1| to theright and causing slider .|8| to be re
one end or the other of its “dead spot.” The pis
turned to its center position as the valves |92 55 ton 2|3 moves toward its center position just far
and |94 are closed by rotation of motor 33.
enough to unbalance the bridge so as to cause one
It should be apparent from the shape of cams
set of poppet valves to open slightly, whereupon
|9|, |92, |93 and |94 that this system has a con
the piston is given an impulse in the opposite
siderable “dead spot.” In other words, there is
direction by the high pressureiluid, thereby un
a considerable angle through which the shaft |90 60 balancing the bridge in the opposite direction and
may rotate without actuating any of the valves
causing >closure of the poppet valves. This ac
|95, |98, |91 and |98. There is of course a cor
tion is cyclically repeated.
responding range of movement of slider |8| on
When the system is operating under these con
either side of its center position in which the
ditions, a slow variation in the temperature of
bridge circuit may be balanced by the movements 65 the engine |50 will cause a change in the median
oi' this slider without causing movements of the
position about which the piston 221 oscillates.
slider Ill. Since- it is permissible to allow the
The slider |8| will continue to oscillate about the
engine temperature to vary about the desired ' same end of its dead spot, thereby causing oper
value by a considerable range, for example 10
ation of the same setv of valves as long as the
or 15°, this construction of the cam permits the 70 rate of change of resistance |55 is lower than the
slider |8| to take care of minor variations in
rate of change of resistance |12 to the movement
temperature without causing unnecessary control
of slider |1|. When the temperature of engine
operations of the servo motor 200. The rela
|50 chan-ges rapidly however, resistance |55 also
tively wide "dead spot” also permits either slider
changes rapidly, causing a greater movement of
|1| or |8| to overrun its exact rebalancing posi 75 slider |8| to open the valves fully. Ii the change
circuit following an unbalance thereof is accom
15
2,403,917
is in the opposite direction, the slider will be
Output terminal 215 is- connected through a
conductor .215, winding 218 of relay 211, a con
moved clearacross its dead spot and will open the
opposite set of valves to produce the required con
trol eiïect on the cowl flaps |54.
ductor 215, transformer secondary winding 255,
'
and a conductor 25| to ground at 252.
It should be understood that this type of con
Output terminal 214 is connected through a
trol is not limited to the system described herein,
but may be applied to other control systems. In
a system where a rapid response is not required
under certain conditions, one set of poppet valves
could be dispensed with, and the system allowed
conductor 255, coil 254 of a relay 255, a conductor
255, the lower half of transformer secondary
winding 255, and conductor 25| to ground at 252.
Secondary winding 255 forms a part of a trans
form'er 251 having a primary winding 255 and
additional- secondary windings 259 and 255.
to oscillate under the control of a single set of
poppet valves.
’ Secondary winding 255 is connected through con
Figure 6
cooled engine |55 by modulating the position of
ductors 255 and 25|, respectively to input ter
minals 25| and 252 of bridge circuit 255. The
secondary winding 255 is connected through con
ductors 255 and 254 to power supply terminals
21| and 212 of amplier 255.
Primary winding 255 is supplied with alternat
the cowl naps |54 in a manner generally similar
ing current by means of an inverter 255 of any
to that disclosed in Figure 4. The system shown
well known type, which is in turn supplied with
In Figure 6 is shown an aircraft engine tem
perature control system utilizing a modiiied em
bodiment of my invention. Figure 6 shows a sys
tem for controlling the temperature of an air
direct current from a battery 255 through con
ductor 251 and 255.
Relay 211 includes a switch arm 555 movable
that used in Fig. 4. A different type of bridge cir
into engagement with a stationary contact 55|
cuit is used however, and a somewhat different
amplifier and motor control system is also used, 25 upon energization of coil 215. Relay 255 includes
in Figure 6 utilizes a temperature responsive re
sistance element |55 which may be the same as
the system being completely electrical, rather
a switch arm 552 movable into engagement with
than partly electrical and partly hydraulic as in
Fig. 4.
a stationary contact 555 upon energization of
coil 254.
Temperature responsive resistance element |55
is connected in a bridge circuit 255 having input
terminals 25| and 252 and output terminals 255
and 254. The upper left arm of bridge circuit
255 connects input terminals 25| with output ter
minal 255 and includes temperature responsive
resistance element |55. The upper right arm of
bridge circuit 255 connects output terminal 255
and input terminal 252, and includes a fixed re
sistance 255. The lower left arm of bridge cir
cuit 255 connects input terminal 25| and output
terminal 254, and includes a ñxed resistance 255,
a conductor 251, and that part of a slide wire
resistance 255 between its left hand terminal and
its cooperating slider 255. Slide wire 255 and
slider 255 constitute a rebalancing potentiometer
for the bridge circuit 255.
The lower right arm of bridge circuit 255 con
nects output terminal 254 with input terminal 252
and includes that part of slide wire 255 between
the slider 255 and its right hand terminal, the
conductor 25|, and an adjustable resistance 252.
The function of resistance 252 is to determine the
control point of the system, in order words, it
determines that temperature adjacent to resist
ance |55 which causes the bridge to be balanced
-
The switches 555 and 552 control the energiza
30 tion of a reversible direct current motor generally
indicated at 554, comprising an armature 555 and
a. pair of field windings 555 and 551. The field
windings 555 and 551 are so connected with re
spect to the armature 555 that their selective
35 energization causes rotation of the motor in op
posite directions.
-
Motor 554 drives, through a gear train schemat
ically indicated at 5|5, a pinion III, which co
operates with a rack 5|2 on a thrust rod 5|5.
40
The thrust rod 5|5 is slideable through a bear
ing 5|4 of any suitable construction, which may
be attached to a fixed part of the air craft.
Pivotally attached to the thrust rod 5|! are a
pair of links 5|5 and 5|5, pivotally connected at
their opposite ends to cowl flaps |54. A motion
reversing link 5 |1 is mounted on a fixed pivot, as
at 5|5, and has one end attached by a suitable
connection such as a pin and slot arrangement,
to the thrust rod 5|5. The other end of link 5|1
50
is pivotally attached to a link 5|5, whose opposite
end is attached to slider 255.
Operation of Figure 6
' The ampliiier 255 is so constructed that when
when the rebalancing potentiometer 255 is in a i
an alternating signal of a predetermined phase is
given position. A variable resistance 255 is con
nected in parallel with the slide wire 255. The
function of resistance 255 is to determine the
amount of movement of slider 255 necessary to
connect a given unbalance of the bridge 255.
Output terminal 255 is connected to an input
terminal 255 or an electronic amplifier 255.
applied to the input terminals 255 and 215, that
branch of the output circuit extending through
output terminal 215 and relay 211 is energized.
When an alternating current signal of the op
posite phase is applied to input terminals 255
and 215, the other branch of the output circuit
including terminal 214 and relay 255 is energized.
It will therefore be apparent that the relays 211
and 255 are selectively energized in accordance
with the direction of unbalance of bridge cir
\ Amplifier 255 may be of any desired type, but I
`prefer to use one of the type disclosed in Figure
2 of the copending application of Albert P. Upton,
Serial No. 437,561, dated April 3, 1942. Output
terminal 254 of bridge'circuit 255 is connected
to ground at 251. and through ground connec
tions 255 to input terminal 215 of amplifier 255.
Amplifier 255 has a pair of power supply ter
mlnals 21| and 212, and a pair of selectively
energizable output terminals 215 and 214. Input
terminal 215. serves. through ground connection
255 as a common return terminal for the output
terminals 215 and 214.
cuit 255.
With the parts in the positions shown in the
drawings, let it Vbe assumed that the temperature
adjacent the temperature responsive element |55
increases above the value which it is desired to
maintain. This increases the resistance between
input terminal 25| and output terminal 255 of
1 bridge circuit 255. This unbalances the bridge
255 in such a direction that an alternating poten
75 tial is applied to ampliiler 255 with the proper
9,403,917
Y n
18
. phase relationship to cause energization ofthe
relay winding 215. 'Energization of relay winding
213 causes switch arm 300 to move into engage
ment with contact 30|, thereby completing an- -
.
a space within said aircraft, duct means for sup
plying air to said space, means i'or utilizing the
motion of the aircraft to induce a iiow oi air
through said duct means, a heater mounted in
said duct means including a iluid fuel burner,
valve means for modulatingly controlling the
energizing circuit for field winding 301 and
armature 355 of motor 304. This energizing cir
cuit may be traced from the lower terminal oi'
supply of fuel to said burner, an element having
battery 2g! through a conductor 320, switch arm
an appreciable temperature coeiiicient -oi' re
300, contact 30|, a conductor 32|, field winding
sistance, means for mounting said element in a
301, brush 322, armature 305, brush 323, and a 10 position exposed to the temperature of the air
conductor 324 to the upper terminal of bat
in said space, a normally substantially balanced
tery 235.
`
electrical network including said element, an
Energization of winding 301 and armature 305
electronic ampliner having an input circuit and
causes'rotation or motor 304 in such a direction
an output circuit, means for rebalancing said net
as to rotate pinion 3| I counter-clockwise, thereby
work, electrical motor means for operating said
driving thrust rod 3|3 to the left. and opening -
cowl flaps |54. Movement of thrust rod 3l! to
the left also acts through links 3|1 and 3|3 to
move slider 253 to the right, thereby increasing
the ressitance between bridge input terminal 25| 20
and output terminal 254, and balancing the in
creased resistance between input terminal 25| and
output terminal 253 due to the increase in engine
temperature. When the bridge is again balanced,
the relay 211 is deenergized and motion ol.' the
cowl ilap |54 and the slider 259 ceases.
If the engine temperature decreases below the
value it is desired to maintain, the bridge 250 is
unbalanced in the opposite direction, thereby
causing energizati'on of winding 284 of relay 285.
Energization of relay winding 284 causes switch
arm 302 to be closed against stationary contact
303, thereby completing an energizing circuit for
winding 306 and armature 305 of motor 304. This
circuit may be traced from the lower terminal
of battery 295 through conductor 320, switch arm
302, contact 303, a conductor 325, iield winding
306, brush 322, armature 305, brush-323, and
conductor 324 to the upper terminal of battery
296. Completion of this circuit causes rotation
of motor 304 in such a direction as to rotate pinion
3|| clockwise thereby driving thrust rod 3I3 to
the right and moving the cowl flaps |54 toward
closed position. This movement of thrust rod
3|3 to the right also drives slider 259 to the left,
thereby rebalancing the bridge circuit 250. I
v
valve means and said rebalancing' means simul
taneously, a, continuously conductive electrical
connection between said network and said input
circuit, and another continuously conductive elec
trical connection between said output circuit and
said motor means. i
3. A system for controlling the temperature of '
an aircraft engine, comprising in combination,
means for cooling said engine, an element having
25 an appreciable temperature coeñicient of resist
ance, means for mounting said element in prox
imity to a part oi said engine, an electronic
amplifier having an input circuit and an output
cir cuit, electrical motor means for controlling said
30 cooling means, a connection between said ele
ment and said input circuit, and a connection
between said output circuit and said motor means.
4. A system for controlling the temperature of
an aircraft engine, comprising in combination,
35 means for cooling said engine, hydraulic means
for operating said cooling means, an element hav
ing an appreciable temperature coemcient of re
sistance, means for mounting said element in
proximity to a part of said engine, an electronic
40 ampliñer having an input circuit and an output
circuit, electrical motor means for` controlling
said hydraulic means, a connection between said
element and said input circuit, and a connection
between said output circuit and said motor means. '
5. uA system for controlling a iluid operated
servo-motor, comprising in combination, means
While I have shown and described certain
for supplying iluid under pressure, valve means
specific embodiments of my invention, other mod
controlling the flow of iluid from said supply
iiications thereof will readily occur to those skilled
means to said servo-motor, a device having an
in the art, and I therefore wish to be limited 50 electrical characteristic variable in accordance
only by the scope of the appended claims.
with a condition indicative of the need for opera.'
I claim as my invention:
tion of said servo-motor, a normally balanced
l. In combination, an aircraft, means deiining
electrical network including said device, said de
a space within said aircraft, duct means iorsup
vice being operative upon a change in said con
plying air to said space, means for utilizing the 55 dition to unbalance said network, means operated
motion oi’ said aircraft to induce a ilow of air
by said servo-motor for rebalancing said network,
through said duct means, heater means in said
an electronic amplifier having an input circuit
duct means, means for controlling the amountv
and an output circuit, means connecting said
of heat transferred by said heater to the air iiow
device and said input circuit, electric motor
ing through said duct means, a temperature re
means for operating said valve means. and means
sponsive resistance element, means for mounting
connecting said electric motor means and said
said element in a position exposed to'the tem
output circuit.
perature of the air in said space, a second tem
6. A system for controlling a fluid operated
perature responsive resistance element, means
servo-motor, comprising in combination, means
for mounting said second element in said duct 65 for supplying iiuid under pressure, valve means
means on the ‘up-stream side of said heater means, »
controlling the flow of iluid from said supply
a normally substantially balanced electrical cir»
vmeans to said servo-motor, a device having an
cuit including both said elements, electronic am
electrical characteristic variable in accordance
plifier means having an input circuit and an
' with a condition indicative oi the need for opera
output circuit, electrical motor means for operat 70 tion of said servo-motor, a normally balanced
ing said control means, an electrical connection
electrical network including said device, said de
between said balanced circuit and said input cir
vice being operative upon a change in said con
cuit, and another electrical connection between
dition to unbalance said network, an electronic
ysaid output circuit and said motor means.
ampliñer having an input circuit and an output
2. :in4 combination, an aircraft, means deñning 15 circuit, means connecting said device and said
2,403,917
.
'
19
.
input circuit, electric motor means for operating
controlling the flow of iluid from said supply`
said valve means, means connecting said electric
means to said fluid motor, leak means in said
motor for permitting slow operation ot said motor
~ motor means'and said output circuit, means op
erated by said electrical motor means for chang
ing the balance condition of said network, and
additional means' operated by said- servo-'motor
for changing‘the balance condition oi said net,-
under the influence of said biased load device
whenl said valve means is closed, a device having
an electrical characteristic variable in accordance
with a condition indicative of the need i’or oper
ation of said load device, a normally balanced
work.
’1. A control system, comprising in t'z'oxnbiniei-`
electrical network including said device, said de->
tion. a pressure operated reversible fluid motor.
means for supplying fluid under pressure, at least
two selectively operable valve means for oo_n
trolling the flow of fluid from said supply means
vice being operative upon a change in said condi..
tion to unbalance said network, means driven
by said nuid motor for changing the balance
to said fluid motor so as to cause operation there
of selectively in either direction, reversible elec
trical motor means .for operating said valve
means, said electrical motor means having\-a
normal position wherein all of said valve means
are closed. and `being operable in opposite direc
tions from said position to selectively open said
valve means, a device having an electrical char
acteristic variable in accordance with a condi
tion indicative of the need for operation o! said
fluid motor, a normally -balanced electrical net
work including said device, said device being
operative upon a change in said condition to
unbalance said network, means responsive to un
balance of said network to energize said electrical
, condition 4of said network, and means responsive
to the balance or unbalance of said network for
operatingsaid valve means.
10. A control lsystem, comprising in combina
tion, a load device biased to a predetermined
position, a pressure operated fluid motor for
~driving said load against its bias, means for
20' supplying fluid under pressure, valve means i'or
controlling the flow of fluid from said supply
means to said fluid motor, leak means in said
motor for permitting slow operation of said motor
under the influence of said biased load device
25 when said valve means is closed, a device having
an electrical characteristic variable in accord
ance with a condition indicative of the need
for operation of said load device. a normally
balanced electrical network including said de
motor means for operation in a direction corfresponding to the direction of said unbalance. 30 vice, said device being operative upon a change
in said condition to unbalance said network,
thereby opening one of said valve means. means
means driven by said fluid motor for changing
driven by said electrical motor means to re
the balance 'condition of said network, second
`balance said network. and means driven by said
valve means for controlling the flow of fluid to
fluid motor to unbalance said network in the
opposite sense, thereby energizing said motor i'or` 35 said motor, said second valve means when open,
permitting the ilow of iluid to said motor so
operation in a direction to close said one valve
as to drive said load -rapidly in the direction of
means and again rebalance said network.
its bias, and means responsive to the balance
8. A control system, comprising in combina
condition of said network for operating said valve
tion, a load device biased to a predetermined
position, a pressure operated fluid motor for 40 means, said balance responsive means opening
said first valve means upon an unbalance of said
driving said load device in opposite directions,'
network in a direction indicative of a need for
means for supplying fluid under pressure, a pair
movement of said load against its bias, and open
ot valve means for controlling the flow of fluid
ing said second valve means only upon a rel
from said supply means to said fluid motor so
atively large unbalance of said network in a
as to cause operation thereof selectively in either
direction indicative o! a need for movement oi
direction, leak means in said motor for permit
said load in the direction of its bias.
ting slow operation of said motor under the ln
11. In combination, an aircraft, means defining
iluence of said biased load device when both said
valve means are closed. reversible electrical motor
means for operating said valve means, said elec- f
trical motor means having a normal position
wherein both oi said valve means are closed,
and being operable in opposite directions from
said position to selectively open said valve means,
a device having an electrical characteristic vari
able in accordance with a condition indicative
of the need for operation of said fluid motor, a
normally balanced electrical network including
said device, said device being operative upon a
change in said condition to unbalance said net
work, means responsive to unbalance of said net
work to energize said electrical motor means for
operation in a direction corresponding to the
direction of said unbalance, thereby opening one
of said valve means. means driven by said elec
trical motormeans to rebalance said network,
and means driven by said iluid motor to change
the balance condition oi' said network in the same
a space within said aircraft, duct means for sup
plying air to said space, means for utilizing the
motion of said aircraft to induce a flow oi‘air
through said duct means, heater means,in said
duct means, means for controlling the amount
of heat transferred by said heater to the air flow
ing through said duct means, a first temperature
responsive resistance element, means for mount»
ing said element in a position exposed to the tem
perature of the air in said space, a second tem
perature responsive resistance element, means for
mounting said second element in said duct means
on the up-stream side of said heater means, a
third temperature responsive resistance element.
means for mounting said third element in said
duct means in the path oi air discharged from
said heater means, said first element having a
resistance at least ten times that of each of said
second and third elements, a bridge circuit in
cluding all said elements in such a manner that
sense as said rebalancing means, so as to cause
a change in any oi the elements in a certain sense
reversal of said electrical motor.
9. A control system, comprising in combina
unbalances the bridge circuit in the same sense,
and means responsive to unbalance of said bridge
tion, a load device biased to a predetermined
position, a pressure operated fluid motor for
means.`
circuit tooperate said heat transfer controlling
12. In combination, an aircraft, means defining
driving said load against its bias, means for
supplying fluid under pressure, valve means ior 75 a, space within said aircraft, duct means for sup
«- amaai?
' plying air to said space, means for utilizing the
motion of said aircraft to induce a flow of air
through said duct means, heater means in said
duct means, means for controlling the amount
of heat transferred by said heater to the air iiow
ing through said duct means, a first temperature
responsive resistance element, means for mount
ing said element in a position exposed to the tem
peî‘ature of the air in said space, a second tem
22
cient of resistance and exposed to the tempera
ture of the air warmed by said heater, means
including said element for producing an alter
hating electrical signal of a phase dependent upon
the direction in which said heat transfer control
means needs to be operated, amplifier means for
controlling the direction of operation of said mo
tor means in accordance with the phase of said
signal, said amplifier means having an input cir
perature responsive resistance element, means for 10 cuit and an output circuit, means coupling said
signal producing means and said input circuit,
mounting said second element in said duct means
means coupling said output circuit and said mo
on the up-stream side of said heater means, a
tor means, and means for supplying said signal
third temperature responsive resistance element,
producing means, said amplifier means, and said
means for mounting said third element in said
duct means in the path of air discharged from 15 motor means with alternating electrical energy
of fixed frequency and predetermined phase rela
said heater means, said first element having a
tionships, said energy supplying means compris
resistance at least ten times and not more than
ing a transformer having a primary winding and
fifty times that of each of said second and third
at least three secondary windings, means con
elements, a bridge circuit including all said ele
ments in such a manner that a change in any of 20 necting one of said secondary windings to said
signal producing means, means connecting a sec
the elements in a certain sense unbalances the
ond of said secondary windings to said amplifier
means, means connecting a third of said sec
sponsive to unbalance of said bridge circuit to
ondary windings and said motor means, and
operate said heater controlling means.
13. Electrical temperature control apparatus 25 means including a battery and an inverter for
supplying said primary Winding with alternating
for an aircraft, comprising in combination, heat
bridge circuit in the same sense, and means re
producing means on said aircraft, means for uti
lizing the fiow‘of air caused by the motion of
said aircraft to conduct air into heat exchange
electrical energy.
`
15. Electrical temperature control apparatus
for an aircraft, comprising in combination, an
relation with said heat producing means, means 30 ï engine on said aircraft, means for utilizing the
flow of air caused by the motion of said aircraft
for controlling the amount of heat transferred
to conduct air into heat exchange relation with
from said heat producing means to said air, re
said engine to cool said engine, damper means
versible electrical motor means for operating said
for controlling the iiow of air into heat ex
heat transfer control means, an electrical re
change relation with said engine, reversible elec
35
sistance element having an appreciable tempera
trical motor means for operating said damper
ture coefficient of resistance and exposed to a
means, an electrical resistance element having
temperature indicative of the need for operation
an appreciable temperature coefficient of resist
ance and exposed to the temperature of said
cluding said element for producing an alternating
engine,
means including said element for produc
electrical signal of a phase dependent upon the 40 `ing an alternating electrical signal of a phase
direction in which said heat transfer control
dependent upon the direction in which said
of said heat transfer control means, means in
means needs to be operated, amplifier means for
controlling the direction of operation of said mo
tor means in accordance with the phase of said
signal, said amplifier means having an input cir
cuit and an output circuit, means coupling said
damper means needs to be operated to maintain
the temperature of. said engine within a predeter
mined range, ampliñer means for controlling the
direction of operation of said motor means in
accordance with the phase of said signal, said
signal producing means and said input circuit,
amplifier means having an input circuit and an
means coupling said output circuit and said mo
output circuit, means coupling said signal‘pro
tor means, and means for supplying said signal 50 ducing means and said input circuit, means cou
producing means, said amplifier means and said
pling said output circuit and said motor means,
motor means with alternating electrical energy
and means fOr Supplying said signal producing
of fixed frequency and predetermined phase re
means, said amplifier means and said motor
lationships, said energy supplying means com- ^
means with alternating electrical energy of nxed
prising a transformer having a primary winding 55 frequency and predetermined phase relationships,
said energy supplying means comprising a trans
and at least three secondary windings, means
connecting one of said secondary windings to said
former having a primary winding and at least
signal producing means, means connecting a sec
three secondary windings, means connecting one
of said secondary windings to said signal produc
ond of said secondary windings to said amplifier
means, means connecting a third of said second
ary windings and said motor means, and means
including a battery and an inverter for supplying
said primary winding with alternating electrical
energy.
14. Electrical temperature control apparatus
for an aircraft, comprising in combination, a
heater on said aircraft,_means for utilizing the
flow of air caused by the motion of said aircraft
to conduct air into heat exchange relation with
said heater to warm said air, means for control
ling the amount of heat transferred from said
heat producing means to said air, reversible elec
trical motor means for operating said heat trans
fer control means, an electrical resistance elc
_ ment having an appreciable temperature coem
ing means, means connecting a second of said
secondary windings to said amplifier means,
means connecting a third of said secondary wind
ings and said motor means, and means including
a battery and an inverter for supplying said pri
mary winding with alternating electrical energy.
16. Electrical control apparatus, comprising in
combination, a load device to be controlled, re
versible electrical motor means for controlling
said load device, means including a device
responsive to a condition indicative of the need
for operation of said load device for producing
an alternating electrical signal of a phase de
pendent upon the direction in which said load
device needs to be operated, ampliñer means for
controlling the direction of operation of said
Y
2,403,917
24
motor means in accordance with the phase of said
signal, said amplißer means having an input cir
cuit and an output circuit, means coupling said
signal producing means and said input circuit,
means coupling said output circuit and said
18. In electrical temperature control apparatus
for an aircraft having heat producing means and
means for utilizing the flow of air caused by
motion oi said aircraft to conduct air into heat
exchange relation with said heat producing
means, means for modulatingly controlling the
motor means, and means .for supplying said
' signal producing means, said amplifier means and
amount of heat transferred from said heat pro
ducing means to said air, an element having an
said motor means with alternating electrical
energy of ilxed frequency and predetermined
phase relationships, saidenergy supplying means
appreciable temperature coefficient of resistance
and exposed to a temperature within said air
comprising a transformer having a primary wind
craft indicative of the need for operation of said
heat transfer control means, a normally substan-~
ing and a plurality of secondary windings, means
connecting one `oi’ said secondary windings to
said signal producing means, means connecting
a second of said secondary windings to said am
pliiler means, means connecting a third of said
secondary windings and said motor means, and
means including a battery and an inverter for
supplying said primary winding with alternating
tially balanced electrical network including said
15
element, an electronic amplifier having an input
circuit and an output circuit, means for rebalanc-.
ing said network, electrical motor means ‘for
operating said heat transfer control means and
said rebalancing means simultaneously, a ccn~
tinuously conductive electrical connection be»1
electrical energy.
20 tween said network and said input circuit, and
i7. In combination. an aircraft, means defining
another continuously conductive electrical con-~
a space within said aircraft, duct means for sup
nection between said output circuit and said mo
DLViIiS air to said space, means for utilizing the
tor means.
motion of said aircraft to induce a flow of air
19. In electrical temperature control apparatus
through said duct means, heater means in said 25
for an aircraft having an engine and means for
duct means, 'means for controlling the amount of
utilizing the ilow of air caused by motion of said
aircraft to conduct air into heat exchange rela
tion with said engine to cool the same, means for
modulatingly controlling the flow of air into heat
ing said element in a position exposed to the
temperature of the air in said space, a second 30 exchange relation with said engine, an element
having an appreciable temperature coefficient oi"
temperature responsive resistance element, means Y
resistance and exposed to the temperature of said
for mounting said second element in said duct
heat transferred by said heater to the air flowing
through said duct means, a iirst temperature
responsive resistance element, means for mount
means on the up-stream side of said heater
engine, a normally substantially balanced elec
means, a third temperature responsive resistance 85 trical network including said element, an elec~
tronic amplifier having an input circuit and an
element, means for mounting said third element
output circuit, means for rebalancing said net
in said duct means in the path of air discharged
work, eiectrical motor means for operating said
from said heater means, one of said elements
air flow controlling means and said rebalancing
having a resistance at least ten times that of
each oi' the other two elements, a bridge circuit 40 means simultaneously, a continuously conductive
electrical connection between said network and
including all said elements in such a manner that
said input circuit, and another continuously con
a change in any of said elements in a certain
ductive electrical connection between said output
sense unbalances the bridge circuit in the same
circuit and said motor means.
sense, and means responsive to unbalance of said
bridge circuit to operate said heat transfer con
trolling means.
WILLIS H. GELE.
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