Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
FIRE PROTECTION SYSTE~ FOR AIRCRAFT
This invention relates in general -to a fire protection
system used for extinguishing fires and more particularly
to an improved fire protection system for aircraft.
The fire extinguishing systems that have been proposed
in the past for use in airplanes and helicopters, as well
as other aerospace vehicles have suffered from numerous
drawbacks. Perhaps most notably, the controls and
procedure for operating the system are typically
complicated, and it may be difficult to operate -the
proper controls in the necessary sequence, especially
under an emergency situation such as a fire. Another
problem is that only a small part of the total
extinguishant material may be available for application to
any one designated fire zone. Therefore, the
additional extinguishant that is present in the system
cannot be applied once the designated portion is
exhausted, even if the additional material is necessary to
put out the fire.
A complete operational check of alI components cannot bs
done as part of a normal preflight inspection. Although
preflight testi~ of portions or co~ponents of some
systems is~p~sible, the testing procedure does;not~always
assure the integrity and~operability~of all components~
of the system. Also, if the contral system or any~of its
components malfunctions~, the fact that a~fault exists is
not indicated until it~is~too late to take corrective
action.
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The present inven~ion is directed to an improved aircraft
fire protection system and has, as its primary object, the
provision of a system which functions ef~ectively and
reliably and which is operated by simple and easily
activated controls. Another important object of the
invention is to provide an aircraft fire protection system
having an easily operated testi~ arra~ement for reliably
testing the entirety of the control circuit and all of its
components as well as the components of the extinguishing
~0 system. The fire protection system also makes the
entire amount of extinguishant material available to each
fire zone if necessary.
It is an objective of the invention to permit the reliable
and simple control of a multiple zone fire protection
system by one or more compact centrally located control
panels that also display~ the status of the system during
operation.
Conventional methods for controlling complex fire
extinguishing and detection systems use pull "Tee handles"
selector switches, push button switches and similar
controls that require a greater amount of space than the
present invention. The operator of, for instance, a
complex 2-zone conventional system must identify the
affected zone, pull the proper Tee handle, select the
proper bottle, and then push the proper discharge
switch. If a second discharge in the same zone is
re~uired he must reselect to another full bottle and then
push the proper discharge switch again. If he wishes
to discharge to a different zone than originally
identified, he may ha~e to first reset the controls
associated with the original zone identified, by at least
resetti~ the "pulled" Tee handle. Then he must proceed
as described above for the new zone. Sometimes, these
actions can be accomplished accurately under stress, but
if more zones are included in a protection system exact
judicious actions will be required to accurately opera~te
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the syst~n. The conventional controls will likely be too
numerous and the actions required too complex for a
reliable system that actually increases the overall sa~ety
of operation of an aerospace vehicle.
In accordance with the invention, an aerospace vehicle
such as an airplane or helicopter is arbitrarily divided
into designated fire zones which are each connected with a
supply manifold and equipped with a solenoid valve for
directing extinguishant material from the manifold to
the corresponding fire zone. The manifold is supplied
with extinguishant material from a series of bottles each
having an electrically actuated detonator. The system
includes a solid state control circuit which detonates the
bottles after previously opening the appropriate valve
or valves to direct extinguishant to the area of the fire.
It is a particularly important feature of the invention
that there is only one switch for each fire zone, and the
controls are simplified accordingly~ Each switch
opens the corresponding valve to arm the system when
pushed once, and subsequent depressions of the switch
detonate the bottles in sequence under the control of
logic circuitry in the control system. Thus, only one
switch must be depressed to fight fire in any zone of
the aircraft, and any desired amount of extinguishant
material can be directed to the fire zone simp~y by
repeatedly depressing the corresponding switch. The
circuitry is arranged to assure that detonation of the
bottles can occur only i there is an open valve.
Also, openi~ of one valve effects automatic closing of
any previously opened valves in order to assure that the
extinguishant material is direFted to the intended area.
Another important feature of the invention is that all
of the bottles and valves can be opened to apply
extinguishant material throughout the aircraft if a crash
is imminent or occurs. Thls is accomplished simply by
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depressing a "crash" switch once to open all valves and
again to detonate all bottles~ An impact switch included
in the control circuitry automatically achieves the same
resul~s (application of extinguishant throughout the
aircraft) if a crash occurs before the pilot has an
opportunity to activate the manual "crash" switcho
The systern further includes a simplified and improved test
circuit for preflight checking of the operability of all
components. The test system is controlled by a single
switch which can be moved to the test position a-t any time
a test is desired. A series of indicator lights then
automatically cycle in sequence to confirm that all valves
can be opened and that all bottles can be detonated. The
actual opening of each valve in sequence in the test
mode is indicated by the lights, as is the fact that
current paths are available through all unopened bottle
detonators. The ability of the valves to actually open
and the detonators to actually discharge the bottles is
thereby confirmed during the test procedure without
the possibility of inadvertent detonation of any bottles
in the test mode. A flashing amber test light provides an
additional indication that the system is in the test
mode. If there is a fault in the system, the test light
~5 does not blink but is constantly on to provide a fault
indication.
An additional feature of importance is the volume selector
switch which permits adjustment of the quantity of
extinguishant directed to any of the fire zones. For
example, if the cargo area is full or nearly full, only a
relatively small amount of extinguishant is required to
fill the open space. Conversely, a larger amount of
extinguishant is necessary if only a small amount oE cargo
is present. Thus, on flights having full cargo
compartments, the volume selector switch can be moved to
the "full cargo" position, and the control circuit
discharges a relati~ely small amount of extinguishant (two
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bottles, for example) each time the cargo switch is
depressed. If the cargo area is relatively empty, the
volume selector switch can be placed in the "empt~ cargo"
position in which a greater quantity of extinguishant
(three bottles, for example) is discharged for each
depression of the cargo switch Such a selector switch
may be associated with each zone switch.
An alternative and somewhat simplified form of the
invention intended primarily for use in smaller
aircraft permits the fire protection system to utilize
either three way valves or two way valves, and its
versatility is increased accordingly. Also, the test and
crash systems are modified somewhat.
Other and further objects of the invention, together with
the features of novelty appurtenant thereto, will appear
in the course of the following description.
In the accompanying drawings which form a part of the
specification and are to be read in conjunction therewith
and in which like reference numerals are used to indicate
like parts in various views:
Fig. 1 is a general diagrammatic illustration of an
aircraft fire protection system constructed according to a
first embodiment of the present invention;
Fig. 2 is an elevational view of the control panel on
which the controls of the fire protection system are
mounted;
Figs. 3-8 are sch~matic circuit diagrams illustrating the
control circuitry which controls the operation of the fire
protection system;
Fig. 9 is a general diagrammatic illustration of the valve
arrangement of a fire protection system constructed
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according to an alternative form of the invention
employing two three way valves for three fire zones;
Figs. lOa-lOh are schematic circuit diagrams illustrating
the control circuitry Eor the system of Fig. 9; and
Fig. lOi is an organizational diagram depicting the manner
in which Figs. 10a~10h are organized in relation to one
another.
Referring now to the drawings in detail, Figs. 1-8
illustrate an aircraft fire protection system constructed
in accordance with a first embodiment of the present
invention. The aircraft can be of any type, and any
number of fire zones within the craft can be
arbitrarily selected. Fig. 1 illustrates an aircraft
having five different major fire zones, namely a cockpit
10, a cargo area 12, an electrical compartment 14, an
engine compartment ~6 and a transmission section 18. It
is to be understood that more or fewer designated fire
zones can be formed, and that the zones illustrated are
given merely by way of example. Also, one or more minor
fire zones can be included in a major zone.
Bottles containing a suitable fire extinguishant are
provided and are illustrated as being seven in number,
again an arbitrarily selected number that can be varied as
desired. The extinguishant bottles 1-7 are designated by
numerals l9a-19g, respectively, and each has a correspond
ing conduit 20a-20g leading to a manifold pipe 22
which is common to all of the bottles. A conduit 24
equipped with a conventional solenoid valve 26 extends
from manifold 22 to the cockpit 10, and another conduit 28
with a solenoid valve 30 leads to the cargo area 12 from
the manifold. Similarly, conduits 32,34 and 36 ~extend
from the manifold to the electrical compartment 14, the
engine compartment 16 and the transmission 18,`
respectively, and are provided with respective solenoid
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valves 38, 40 and 42.
Conduit 24 terminates in a plurality of nozzles 44 which
serve to discharge the fire extinguishant material into
cockpit 10 in the event of a fire in the cockpit.
Conduit 28 has a plurality of similar no~zles 46 in the
ca~o area, while the remaining conduits 14, 16 and 18
likewise terminate in respective sets of nozzles 48, 50
and 52 in the electrical compar~ment, the engine
compartment and the transmission, respecti~ely.
Referring now to Fig. 2, the fire protection system has a
control panel which is generally indicated by numeral
54. The control panel is preferably mounted at a
convenient location within the aircraft, such as on
the instrument panel, where it is readily accessible to
the pilot, pilots or other personnel. Control panel 54
includes a main panel 56 and an auxiliary panel 58,
although the controls can be mounted on a single panel if
desired. The upper main panel 56 has a test-reset
toggle switch 60 which is in the "off" condition in the
center position shown. Switch 60 can be moved upwardly to
the "test" position or downwardly to the "reset" position,
as will be described in more detail. Above the togyle
switch 60 is a small light 62 formed by an LED covered
by an amber colored lens.
The main control panel 56 also includes a cockpit switch
64, a cargo area switch 66 and an electrical compartment
switch 68, all of which are push button switches that
return to their normal extended positions after being
depressed and released. A crash switch 70 located beside
switch 68 is of the same type7 A toggle switch 72 for
controlling the volume of extinguishant material
discharged into the cargo area of the aircraft is
located below the cargo switch 66 and has both an empty
cargo setting and a f~Il cargo setting. A bell switch 74
located below the electrical compartment switch 68 has
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"off" and "on" settings. A small light 76 located beside
bell switch 74 indicates the setting of the bell switch
and is preferably an LEl) covered by an amber lens.
5 The main control panel has two rows of lights each
having seven lights corresponding to the extinguishant
bottles 1-7. The lights in the top row are designated
78a-78g and those in the bottom row are designated 80a-
80g. The lights 78a and 80a correspond to bottle number
10 1, lights 78b and 80b correspond to bottle number 2,
and so forth. The top lights are preferably LEDs covered
by green lenses, and the bottom lights are LEDs covered by
amber lenses.
15 The auxiliary panel 58 may be located adjacent to or
separated from the main panel. Panel 58 has an engine
canpartment switch 82 and a transmission switch 84, both
of which are push button switches of the same type as
switches 64-70. All of the switches on the control panel
20 are marked appropriately, as indicated. Switches 64-
70 and 82-84 preferably have covers which must be
intentionally lifted to provide access to the push buttons
in order to prevent inadvertent depression of any of the
buttons. The lower or "ARMED" half of each switch 64-70
25 and 82-84 has a pair of lights which display a green
color when energized, and the upper half of each switch
has a pair of lights which display a red color when
energized, as wil~ be explained more fully.
30 Turning now to the control circuit for the fire
protection system, Fig. 3 illustrates a power lead 86
which supplies 28 volts from any suitable power source,
such as the aircraft power system or a separate battery
pack that still functions if there is a loss of electrical
35 power in the aircraft system. The power lead 86 is
connected with the power supply by~ a circuit breaker or
thè like (not shown) whlch is normally closed. ~A 28 volt
power bus 88 connects with~power lead 86 to;~provide 28
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volts to various parts of the system, as will be
described.
The 28 volt power lead is provided with a diode 90, a pair
5 of filtering capacitors 92 and 94 tied to ground, and
a choke coil 96. The power lead connects with a voltage
regulator 98 providing appro~cimately 12 volts on its
output line 102. A 12 volt bus 102 connects with line 100
to supply various parts of the system with 12 volts. Also
10 connecting with line 100 is another line 104 leading
to an amplifier 106 through a capacitor 108. The output
fr~n amplifier 106 is applied to a reset bus 110 which
applies a reset pulse when energized. Line 104 connects
to another amplifier 112, the output of which is applied
15 to a POR bus 114.
Referring now to Figs. 7 and 8, the 12 volt power bus 102
connects with lines 116a, 116b and 116c, and also to lines
116d and 116e (Fig. 8). Switches 64-68 and 82-84 each
20 have two sets of contacts, and lines 116a-116e lead to
the canmon contacts of the respective switches. In the
normal positions of the switches shown, lines 116a-116e
connect only with lines 118a-118e, respectively. However,
when each switch is depressed to connect its ccmmon
25 contacts with its normally open contacts, lines 116a-
116e connect r0spectively with lines 120a-120e through one
set of contacts and with lines 122a-122e through the s~ne
set of contacts. Also, lines 116a-1 16e connect with lines
124a-124e through the other set of contacts.
Lines 120a-~20e connect with respective pairs o~ green
lamps 126a-126e which are arranged in parallel with one
anoth0r and are located in the "ARMED" hal~ of the
respective switches 64-68 and 82-840 The opposite sides
35 of the lamps 126a-126e connect with respective lines
128a-128e which lead to a co~nmon ground line 130. Also
connected with lines 128a-1 28e are respective pairs of red
lamps 132a-132e that may have their opposite sides tied to
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a conventional fire detection sys~em (not shown) operating
to light the red lamps 132a-132e in the event a fire is
detected in the appropriate fire zone.
By way of example, a conventional fire detector (not
shown~ closes a suitable switch that applies
approximately 28 volts to an engine fire alarm line 133
lFig. 8) if a fire is detected in the engine compartment
of the aircraft. The red lamps 132d in the upper half of
switch 82 are then energized to give an "engine fire"
indication to the pilot. Similarly, the detection
system applies 28 volts to a gearbox alarm line ~34 (Fig.
7) leading to the ball switch 74 and also to a conductor
135. As shown in Fig. 8, conductor 135 connects with the
red lamps 132e which are then energized to indicate on the
transmission switch 84 that a transmission fire has
been detected.
When the bell switch 74 is in the "on`' position shown in
Fig. 7, its lower set of contacts connect line 134 with a
bell power line 136 leading to ground through a bell
(not shown) which gives an audible indication of the
presence of a fire in the transmission or gearbox section
of the air`~raft The upper set of contacts of the bell
switch 74 open a circuit 137 extending between the 12 volt
bus 102 and ground line 130. The amber bell silent
light 76 is then deenergized to indicate that the audible
bell signal has not been switched off. If bell switch 74
is switched to the off position, lines 134 and 136 are
disconnected by the lower set of switch contacts and the
bell cannot sound an alarm. At the same time, circuit
137 is completed to energize LED 76 to indicate that the
bell is switched off. Ordinarily, the bell switch 74 will
be switched off only after the bell has audibly indicated
the detection of a transmission fire.
Lines 122a-122e are "valve open" lines VOl, V02, V03, V04,
and V05, respectivel~. Lines 122a-122c connect through
pins 6, 7 and 5 of a connector 138 with corresponding
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inputs to a multiple input OR gate ~39 shown in Fig. 3,
Lines 122d and L22e connect through pins 3 and 2 of the
connector with OR gate 139. The output signal of gate 139
is applied through NOR gates 139a and 139b to an AVO (any
5 valve open) bus 140 and is also applied to the base of
a transistor 141. The 12 volt bus 102 connects through
transistor 141 with a green LED gang line 142 when the
transistor base receives an output signal from the OR gate
139.
Lines 122a-122e also bypass o~ gate 139 and, as shown in
Fig. 4, connect with respective logic gates 144a-144e
which in canbination with associated gates 146a-146e form
valve latch circuits for opening the valves shown in Fig.
15 1. The other input signal to each latch circuit is
provided on a RES' bus 148 which connects with the reset
(RES) bus 110 and the POR bus 114. The output signals
from the valve latch circuits are applied to the bases of
respective transistors 150a-150e. When the transistor
20 bases receive high signals from the latch circuits,
respective relay coils RVl, RV2, RV3, RV4 and RV5 are
energized since the transistors are then conductive to
provide a ground path frcm the 12 volt bus 102 through the
relay coils.
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The relay coils when ener~ized close their respective
pairs of normally open contacts RVl, RV2, RV3, RV4 and RV5
in order to canplete circuits to ground fram the 28 volt
bus 88 through respective solenoid coils VC1, VC2, VC3,
30 VC4 and VC5. These solenoids open the respective
valves 26, 30, 38, 40 and 42 (Fig. 1) when energized to
pe3mit extinguishant to flow fran manifold 22 to the
corresponding fire zones of the aircraft.
35 When any of the solenoid coils is energized to open
the corresponding valve, the valve~core (not shown)
physically closes a pair of normally open switches which
are respectively designated VClA and VClB, VC2A and VC2B,
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VC3A and vC3s, VC4A and VC4~, and VC5A and Vc5s in Fig.
4. Closing of switches VClA-VC5A applies 12 volts from
-the ~2 volt bus 102 to respective lines 152a-152e which,
as shown in Fig. 3, connect with the respective VOl-VO5
lines 122a-122e to provide holding circuits that
maintain the VO (valve open) lines energized after the
corresponding switch 64-68 or 82-84 is released. The
other switches vclB-vc5s are used to visually indicate
closing of the corresponding valve.
Referring again to Fig. 4, the VO lines 122a-122e connect
through capacitors 153a-153e with respective amplifiers
154a-154e which are tied on their output sides with a
common line 156 forming one input to a NAND gate 158. The
output from gate 158 is applied to an inverter 160
which connects with a line 162 that leads to the RES' bus
148. The reset (RES) bus 110 also connects via line 162
with the RES' bus 148.
The output signals from the valve latch circuits
formed by logic gates 144a-144e and 146a-146e (Fig. 4) are
applied, in addition to transistors 150a-150e, to
respective lines 164a-164e. Capacitors 165a-165e
(4.7micro F) are tied between the respective lines 164a-
164e and ground. Lines 164a-164e connect as one input
to respective NAND gates 166a-166e (Fig. 5).
With reference again to Fig. 7, lines 118a-118c are
designated CPA, CGA, and ELA, respectively, and connect
through pins 47, 44 and 49 of connector 138 with
respective NOR gates 168a-168c (Fig. 5). Similarly, lines
118d and 118e (Fig. 8) are designated ENA and GBA and
provide one input to respective NOR gates 168d and 168e.
The gates 168a-168e form latching circuits in cooperation
with associated NOR gates 170a-170e, respectively,
which receive one input from the respective lines 124a-
1~4e (designated CPA', CGA', ELA', ENA' and GBA') leading
from the push button switches 64-68 and 82-84 (see Figs. 7
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and 8). The output signals fr~n the latch circuits formed
by gates 168a-168e and 170a-170e are applied to the
respective NAND gates 166a-166e through .002 micro F
capacitors 172a-172e. As previously indicated, gates
166a-166e have their other input pins connected with
lines 164a-164e.
The output lines of gates 166a-166e connect with the "15"
input pins of respective decade counter circuits 174a-174e
~4017 integrated circuits) having their "14" input
pins tied to a ccmmon clock line 176. A firing pulse
generator (F~G) clock circuit 178 provides 8.7 KH~. pulses
to the clock line 176. Each input signal on pin 15
generates an output signal on the "2" output pin of each
decade counter 174a and 174c-174e which is applied to
FPG bus 180. The decade counters are then inhibited until
another input signal appears on pin 15.
The decade counter 174b corresponding to the cargo area of
the aircraft has its "2" and "7" output pins tied to
the FPG bus 180 and its "6" output pin connected to an
open circuit 182 leading to a connector 184. The "1'
output pin of decade counter 174b connects through
connector 184 with a high volume line 186 which, as shown
in Fig. 7, connects with the cargo load switch 72.
Line 186 is an open circuit in the "high" setting of
switch 72 but connects in the "low" setting of the switch
with a low volume line 188. As shown in Fig. 5, line 188
leads back through ~onnector 184 to connection with the
FPG bus 180.
The connection of gate 166b and decade counter 174b is not
direct but is through an inverter 190 and a latch circuit
formed by interconnected NOR gates 192 and 194. The
output line of gate 192 connects with the "15" pin of
decade counter 174b, and the "11" pin of the~ decade
counter is connected with one input of gate 194.
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The circuitry associated with the crash switch 70 differs
somewhat from that associated with the fire zone switches
64-68 and 82-84. As shown in Fig. 7, the two ccmmon
contacts of switch 70 are connected with the 12 volt bus
by line 116f. When switch 70 is in the normal
position shown, 12 volts is applied through one set of
contacts to a CHA line 118f. When switch 70 is depressed,
12 volts is applied through one set of contacts to a V06
line 122f and through the other set of contacts to a CHA'
line 124f.
A pair of amber lamps 126f are located behind the crash
switch 70 and are arranged in parallel. One side of each
lamp 126f is tied to a line 128f whch connects with the
ground line 130, and the opposite sides of the lamps
connect with a CSL (crash switch lights) line 196.
The V06 line 122f connects through pin 4 of connector 138
with the multiple input OR gate 139 (Fig. 3~ and continues
on to connection with a crash bus 198 (Fig. 4). An
inverter 199 connects with the crash bus 198 and provides
the second input to NAND gate 158. The crash bus 198
connects with the VOl-VO5 lines 122a-122e and also with a
V07 line 122g which is a spare circuit in the illustrated
embodiment of the invention but which can be used with
the associated spare components in connection with an
additional designated fire zone in the aircraft if
desired. Line 122f connects additionally with a NOR gate
144f forming a latch circuit in cooperation with another
NOR gate 146f. The output from gate 144f is applied
to a series of drivers 197 in order to ene~ize the crash
switch lights 126f via the CSL line 196.
Gate 146f connects at one input with the output line from
gate 144f and at the other input with the RES' bus
148. The output line fr~n gate 146f connects with one
input to gate 144f and also with a conductor 164f. Line
164f is grounded through a capacitor 165f and connects
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with a NAND gate 166f (Fig 5). The other input to gate
166f comes from the CHA and CHA' lines 1~8f and 124f
through a latch circuit formed by a pair of 1O3ic gates
168f and 170f. The output signal from the latch circuit
is applied to gate 166f through a capacitor 172f.
The output Erom gate 166f connects with the "15" input pin
of a decade counter 174f which connects at its "14" pin
with the 8.7 KHz clock line 176. Decade counter 174f is
identical to decade counters 174a-174e but has its
output pins 7, 2, 1, 6 and 11 connected with the FPG bus
and its inhibit pin 13 grounded.
Referring now to Fig. 6, the FPG bus connects via line 199
with one input of a three input NAND gate 200. The
AVO bus 140 provides the second input to gate 200, and the
third input comes from a NAND gate 202 which also provides
the input to inverter 204a. The output from gate 200 is
applied to gate 202 and also to an inverter 206aO Gate
200 and the associated circuitry corresponds to the
first or number l extinguishant bottle l9a~
The FPG bus also connects with a plurality of identical
AND gates 208b-208g corresponding to the respective
extinguishant bottles l9b-19g. The second input to
each gate 208b-208g ccmes from the AVO bus 140, and the
third input comes from the preceding inverter 204a-204f.
The output signal from each gate 208b-208f fonms one input
to a corresponding NAND gate 210b-210f, and the last gate
208g connects with an inverter 212. The output
signals from gates 210b-210f are applied to respective
inverters 206b-206f and also to respective NAND gates
214b-2~4f. Gates 214b-214f provide the second input to
gates 210b-210f, respectively, and both inputs to the
respective inverters 204b-204f.
The inverter 212 corresponding to the last or number 7
bottle l9g provides one input to another MAND gate 216.
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The output signal frcm gate 216 is applied to 1~ ic gate
218 and inverter 220.
The output signals from inverters 206a-206f and inverter
220 are applied to bottle latch circuits formed by
respective pairs of NOR gates 222a-222g and 224a-224g.
The output signal from gates 224b-224f are fed back to the
respective gatas 214b-214f as the second input signal
thereto and are also applied to the bases of respective
transistors 226a-226f through resistors 228b-228f.
gate 224a provides ~he second and third inputs to the
three input NAND gate 202 and is connected with the base
of transistor 226a through resistor 228a. Gate 224g of
the last or number 7 bottle latch circuit provides the
second input to gate 218 and is connected through
resistor 228g with the base of transistor 226g.
When transistors 226a-226g are conductive, circuits are
completed to ground from the 12 volt bus 102 through
respective relay coils RDl-RD7. The sets of contacts
for the respective relay coils are designated RDl-RD7 and
normally have power available from the 28 volt bus 88
through the contacts RTl of a test relay and through
respective diodes 229a-229g. When contacts RDl-RD7 are
closed due to energization of the corresponding relay
coils, the 28 volt bus is connected through the relay
contacts with bottle detonator circuits for the number 1-7
extinguishant bottles l9a-19g. The respective detonator
circuits include fuses 230a-230g and detonator bridges
232a-232g which connect with ground. When supplied
with sufficient current, the bridge~s 232a-232g actuate
respective bottle electrical initiators for the respective
bottles l9a-19g to discharge the contents thereof.
Respective pressure switches~PSl-PS7 associated with
the number 1 ~7 extinguishant~bottles l9a-19g are normally
held open by the pressure wlthin the charged bottles but
close when the correspondlng~bottle is discharged and the
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pressure therein drops. Switches PS1-PS7 are connected on
one side with ground and on the other side with respective
conductors 234a-234g. The lines 234a-234g have respective
diodes 236a-236g and connect with the normally open relay
contacts RDl-RD7, respectively.
The 12 volt bus supplies power to an amber LED gang line
238, as shown in Fig. 3, The amber gang line 238 leads to
the amber LEDs ~Oa-80g (see Fig. 7) which connect on their
opposite sides with lines 242a-242g, respectively. As
shown in Fig. 6, lines 242a-242g connect with the respec-
tive lines 234a-234g between diodes 236a-236g and the
pressure switches.
The green LEDs 78a-78g connect with the green gang
line 142 on one side, as previously indicated. On their
opposite sides, LEDs 78a-78g connect with lines 244a-244g,
respectivel~ (Fig. 7). As shown in Fig. 6, lines 244a-
244g lead to the respective bottle detonator circuits and
connect therewith between the relay contacts RDl-RD7
and the fuses 230a-230g.
A conventional impact or gravity switch 246 (Fig. 3) is
normally open but closes momentarily in response to the
impact involved in a crash of the aircraft. Closing
of switch 246 results in the application of power to a
conductor 248 provided with a diode 250. Conductor 248
contains the impact switch and connects with the crash
line 198 as shown in Fig. 4.
Also connecting with line 248 is a latch circuit formed by
a pair of NOR gates 250 and 2520 A resis~or 254 and
capacitor 2S6 connect one input line of gate 250 with
ground. The reset line lla provides one input to the
other gate 2S2. The output signal from the latch
circuit comes from gate 250 and is applied to a conductor
258 which, as shown in Fig. 5, leads to an inverter 260.
The output signal fr o~inverter 260 forms one input to a
:
~.
, . . . , . ., , . : : - . . , ,:
.,. ~,
: ~: , ~ ', . '' ,., :
. - , , ; .. ,
--18--
three input NAND gate 262 receiving its other input
signals from the AVO bus 140 and the clock circuit 178.
The output fran gate 262 is applied to the FPG bus 180.
5 As shown in Fig. 7, the test-reset toggle switch 60 is
no~nally off but connects +12 volts with a manual reset
line 264 when moved to the "reset" position. Line 264
leads through pin 35 of connector 138 and through a
capacitor 266 (see Fig. 3) to an amplifier 268 which
10 connects with the RES line 110 to provide a reset
si~nal.
When switch 60 is moved to the "test" position, it
connects +12 volts with a test line 27û (Fig. 7). The
15 test line 270 leads through pin 34 of connector 138 to
RTl and RT2 relay coils ~Fig. 3). Coil RTl controls the
RTl relay contacts previously mentioned in connection with
the bottle detonator circuits shown in ~ig~ 6.
20 With continued reference to Fig. 3, the test line 270
connects with an inverter 272 which applies its output
signal through a capacitor 274 to a pair of amplifiers 276
and 278 which connect with the POR line 114 and the RES
line 110, respectively. Line 270 also connects through
25 another capacitor 280 with another pair of amplifiers
282 and 284. Amplifier 282 connects with the RES line
110, and the other amplifier 284 connects with the POR
line 114.
30 The test line 270 provides one input to an AND gate
286. The second input to gate 286 is applied by a
conductor 288 which, as shown in Fig. 6, extends frcm the
output line of the last or number 7 bottle latch clrcuit
formed by gates 222g and 224g. Gate 286 applies its
35 output signal to a NAND gate 290 which receives its
other input frcm another inverter 292~ The input to gate
292 comes from a three input AND gate 294. A test clock
circuit 296 (operating slowly at about one Hz.) applies
.. .i .
. .
,
:: . ~: ,
- ': ` , ~ , .
-19-
one input to gate 294, and test line 270 provides another
input.
The test circuitry of the fire protection system also
includes a pair of inverters 298 and 300 which provide
the input signals to an AND gate 302. The input signal to
inverter 300 comes from the test line 270, while the input
to inverter 298 comes from a conductor 304 which is
connected with or disconnected from -the 28 volt bus 88
under the control of the test relay contacts RTl, as
shown in Fig. 6.
Gate 302 provides one input to a NOR gate 306 receiving
its other input from an AND gate 308. Lines 270 and 304
connect with the input pins of gate 308. The output
from gate 306 forms the third input to gate 294 and is
also applied to inverter 310. Another NOR gate 312
receives one input signal from inverter 310 and the other
from gate 294. The output fr~n gate 294 is also applied
to a test circuit (TC) line 314. The output line 316
from NOR gate 312 is a fault light line that leads to
light 62, as shown in Fig. 7.
Referring again to Fig. 3, the output line of gate 290
connects with a NAND gate 318 which receives its other
input from an inverter 320. The input to inverter 320
comes rom gate 318 through a capacitor 322. The output
signal from gate 318 is applied to a TC POR line 324 and
to an amplifier 326 which connects with the POR line 114.
The output from gate 290 is also applied to input pin 3 of
a flip flop circuit 328 which is a D-type flip flop
circuit having a second section 330. The output signal
from flip flop circuit 328 on pin 1 connects with circuit
330 and with a conductor 332 fonming one input line to
3-input AND gates 334a, 334c and 334e. The second output
~ignal from circuit 328 is on pin 2 and is applied to a
conductor 336 which forms one input line ~or 3-input AND
-20-
gates 334b, 334d and 334f. Three-input AND ya-te 334g and
the associated circuit elements are spare components in
the illustrated form of the invention but can be utilized
if desired.
Pin 13 of circuit 330 provides the first output signal
therefrom and is connected with input pin 3 of another
flip flop circuit 338 and with a conductor 340 providing
inputs to gates 334a, 334b, 334e and 334f. The second
output Erom circuit 330 on pin 9 thereof is applied
via line 342 to gates 334c, 334d and 334g. The 1 output
pin of circuit 338 is connected to line 344 which applies
input signals to gates 334a-334d. Line 346 connects with
output pin 2 of circuit 338 and with gates 334e and
334f. Circuit 338 has a second section 348 with
output lines connected to gate 334g.
The output signals from gates 334a-334f are applied to
respective AND gates 350a-350f which receive their other
inputs from the TC line 314. Gates 350a-350f apply
signals to respective conductors 351a-351f which connect
through diodes with the output lines from the latch
circuits formed by gates 168a-168f and 170a-170f, as shown
in Fig. 5. Gates 350a-350f also connect with respective
inverters 352a-352f which in turn connect with the
bases of respective test transistors 354a-354g. When the
test transistors are conductive, they provide circuit
paths for applying +12 volts to test valve open lines
(TV01-TV06) which are designated 356a-356f,
respectively. As shown in Fig. 4, the TVO lines 356a-
356f connect with the corresponding VO lines 122a-122f.
Referring again to Fig. 3, lines 332, 342 and 346 connect
with the three input pins of an AND gate 358 which applies
its output to a NOR gate 360. The RES line ~l0
provides the other input to gate 360, and its output is
applied through an inverter 362 to the ~6 pins of cir~cuits
328 and 338 and the #8 pins of circuits 330 an~ 348. The
:
. - ,. . : : .
-21-
output frcm gate 360 is also applied to a NAND gate 364
having its output applied through a capacitor 366 to an
inverter 368. The inverter 368 provides the second input
to gate 364. The output line 370 of gate 364 is connected
through a capacitor 372 to an amplifier 374, as shown
in Fig. 4. The output line of amplifier 374 connects
through a diode 376 with one input to NAND gate 158.
The fire protection system is placed in operating
condition by closing the circuit breaker (not shown)
that connects the power supply with the 28 volt lines 86
and 88. The voltage regulator then provides power for the
12 volt bus 102 and applies a reset pulse on the RES line
110 through capacitor 108 and amplifier 106 and a POR
pulse on line 114 through capacitor 108 and amplifier
112. Among other functions, the RES and POR pulses that
pass through capacitor 108 generate a signal on RES' line
148 ~Fig. 4) which resets the valve latch circuits formed
by gates 144a-144e and 146a-146e and also resets the latch
circuit formed by gates 144f and 146f. In addition,
the POR pulse resets the bottle latch circuits formed by
gates 222a-222g and 224a 224g (see Fig. 6).
In operation of the fire protection s~stem, a fire in any
of the designated fire zones is either detected by a
suitable detection system or is sensed by the pilot of the
aircraft or other personnel. In the event of a fire in
the cockpit 10, for example, the ccckpit switch 64 is
pushed once to arm the system by opening valve 26 and is
pushed subsequently one or more times to discharge one
or more of the exti~uishant bottles l9a-19g in order to
apply extinguishant to manifold 22 and through the open
valve 26 and conduit 24 to the cockpit nozzles 44.
When switch 64 is depressed initiaIly, its contacts
are moved from the normal position shown in Fig. 7 such
that the green cockpit lights 126a are energized beneath
the lower "ARMED PUSH TO DISCHARGE" section of the cockpit
, .
,,; . . ; "~ .,
.
--2 2--
switch 64 (see Fig. 2). This provides a visual indication
on the cockpit switch that the system is armed and will
apply extin~uishant upon another depression of the switch.
S Depression o~ switch 64 also applies +12 volts to the
VOl line 122a which connects with the multiple input OR
gate 139 shown in Fig. 3. The resulting output signal
fran gate 139 is applied to the AVO bus 140 and to the
base of transistor 141 to make the transistor conductive,
10 thus applyin~ +12 volts to the green LED gang line
142. The VOl line 122a also applies power to the latch
circuit forned by gates 14~a and 146a (Fig. 4). The high
output from the latch circuit is applied to the base of
transistor 150a to make the transistor conductive. Relay
15 coil RVl is thereby energizedr and the RVl relay
contacts connect ~28 ~olts with solenoid coil VCl to
effect opening of the cockpit valve 26.
When solenoid VC~ is energized, contact VClA connects ~12
20 volts with line 152a which in turn connects with the
VOl line 122a as shown in Fig. 3. This c~npletes the
holding circuit which bypasses switch 64 and thereafter
maintains valve 26 open when switch 64 is released
following its initial depression. The holding circuit
25 maintains power on the ~7Ol input to OR gate 139 and on
solenoid coil VCl until the RES' line 148 is energized to
reset the latch circuit formed by gates 144a and 146a.
With power on the green LED gang line 142, a current path
30 to ground is ca[lpleted through the green LEDs 78a-78g,
lines 244a-244g and the respective bottle detonator
circui~s which include fuses 230a-230g and detonator
bridges 232a-232g. If any of the extinguishant bottles
19a-19g has been used, its detonator bridge will be broken
35 to break the circuit that would otherwise energize the
corresponding green LED 78a-78g. Thus, the greqn LEDs ;
that are energized on the control panel 54 indicate which
bottles are available, and ;the absence of a green light
^--
.' : : :, ,: . :,~
- .
- : :
~ .
--23--
for a particular bottle indicates that such bo-ttle has
already been used and is unavailable.
It is important to note that the circuits that are
5 completed through the detonator bridges 232a-232g are
powered by 12 volts and pass through the green LEDs 78a-
78g (and their internal resistances) as well as the
associated 2.2 Kohm resistors. The current passing
through the detonator bridges is thus relatively small and
10 is insufficient to detonate the bridges. Typically,
the current applied to the bridges in this situation is on
the order of about 10 milliamps, whereas about 200 to 500
milliamps is required to detonate the bottles.
15 Referring again to Fig. 7, it is noted that depression
of switch 64 applies 12 volts to the CPA' line 124a, and
that the signal on line 124 is applied to gate 170a (Fig.
S) to activate the associated latch circuit. A pulse is
thereby applied momentarily through the .002micro F
20 capacitor 172a to gate 166a. The capacitor 172a
quickly becnes charged, and the high input signal to gate
166a is then removed since current no longer passes
through ~he charged capacitor. The other input to gate
166a comes from line 164a and is delayed until capacitor
25 165a (Fig. 4) is fully charged. Due to the relatively
large capacitance of capacitor 165a (4~7micro F) compared
to that of capacitor 172a (.002micro F) the momentary high
signal applied to gate 166a through capacitor 172a is no
longer present when the high signal on line 164a reaches
30 the other input of gate 166a. Consequently, there is
no output generated from gate 166a upon initial depression
of switch 64, and decade counter 174a remains inactive and
does not apply a firing pulse to the FPG bus 180.
35 When switch 64 is depressed a second time, the CPA'
line 124a is once again energized and a second momentary
high signal is applied to gate 166a through capacitor
172a. Since the holding circuit continuously maintains
, . ,.. , : ... , . ,. :
.
~ . .
24-
the VOl line 122a in a high state, line 164a remains
continuously high, and gate 166a receives two high inputs
the second time switch 64 is depressed. The resulting
pulse applied to pin 15 of decade counter 174a generates
an output pulse on pin 2 which is applied to th~ FPG
bus 180 and to one input pin of each yate 200 and 208b-
2089 (Fig. 6).
At this time, the output from each inverter 204a-204f is
low, so none of the gates 208b-208f provides an output
signal in response to the firing pulse on the FPG bus
180. However, gate 202 provides a high output which is
applied as one input to gate 200. The other inputs to
gate 200 come from the FPG bus 180 (via line 199) and from
the AVO bus 140 which is maintained in a high state by
the OR gate 139. Gate 200 is thus active and provides a
pulse to inverter 206a which in turn activates the bottle
latch circuit formed by gates 222a and 224a. The output
signal from gate 224a is applied to the base of transistor
226a, thereby making the transistor conductive and
energizing relay coil RDl. The associated relay contacts
RDl then complete the 28 volt circuit through the
detonator bridge 232a to discharge the number one bottle
l9a. Extinguishant is directed through the open valve 26
to the cockpit 10 and is applied to the cockpit fire
through nozzles 44.
It should be apparent that discharge of the extinguishant
bottle cannot occur unless valve 26 is open because line
164a (i.e. valve latch 144a-146a "on") and the AVO bus
140 (i.e. valve 26 energized and moved to the open
position, thus closing the con-tacts of switch VClA) are in
the high state only if there is a signal on the VOl line
122a indicating that the valve is open. In this manner,
the circuitry assures that there is a valve open
before it is possible to detonate any of the bottles.
:
If one bottle of extinguishant is insufficient to control
.
,
-25
the fire, switch 64 can be depressed repeat~ ly to
discharge a subsequent bottle ~or each subsequent depres-
sion of the switch. When switch 64 is depressed for the
third time, a second firing pulse is applied to the EPG
bus 180 in the same manner as the first firing
pulse. Following the first firing pulse, the output line
of gate 200 reverts to its normal high state and provides
a high input to gate 202. The other inputs to yate 202
are also high because the output line from gate 224a is
latched in a high state in the absence of a POR reset
pulse on line ~14. Gate 202 thus provides a low output
which is applied to gate 200 such that it is inactive at
the time the second firing pulse reaches it. However,
gate 208b is active at this time since inverter 204a
provides a high illpUt to it and the AVO bus 140
remains in a high state. Thus, AND gate 208b applies a
high input signal to NAND gate 2~0b which has a high
signal on its other input pin. Gate 210b provides a pulse
through inverter 206b and activates the latch circuit
formed by NOR gates 222b and 224b. Transistor 226b is
then conductive and the RD2 relay contacts close to apply
28 volts to detonator bridge 232b for detonation of the
second bottle ~9b.
Subsequent depressions of switch 64 effect detonation
of bottles l9c-19g in sequence in the same manner. Each
time a bottle is discharged, the associated detonator
bridge 232a-232g is destroyed and the path to ground
through the corresponding green LED 78a-78g is
interrupted. Each time a bottle is discharged, the
corresponding pressure switah PSl-PS7 closes due to the
pressure drop in the bottle. This completes a circuit
path to ground for the corresponding amber LED 80a-80g.
Consequently, each bottle that 1s~discharged results in
energization of the associated amber LED 80a-80g and
deenergization of the associated green LED 78a-78g to
provide a visual indication~that the bottle has been
discharged and is no longe~r available.
"~
- :
--25--
Each of the switches 66-68 and 8~-8~ for the remaining
fire zones can be depressed once to open the corresponding
valve in the same manner described in connection with the
cockpit valve 26 and subsequently to discharge one or more
5 extinguishant bottles, also in the manner described
previously. The number of bottles that are discharged for
each depression of the cargo switch 66 following the first
depression depends upon the setting of the volume selector
switch 72. With reference to Fig. 5, each pulse applied
10 to the input pin 15 of the decade counter 174b
associated with the cargo canpartment effects four output
pulses in sequence on output pins 2, 7, 4 and 6. The
first two output pulses on pins 2 and 7 are applied
directly to the FPG bus 180 and thus effect detonation of
15 bottles l9a and l9b (or the first two available
bottles) in sequence in the manner described previously.
The output on pin 1 is applied to line 186 and has no
effect if switch 72 is in the "full cargo" setting shown
in Fig. 7. However, if switch 72 is set in the "empty
20 cargo" position, line 186 is connected with line 188
and the output pulse appearing on pin 1 of circuit 174b is
applied to the FPG bus 180 to effect detonation of the
third bottle l9c (or the third available bottle). The
fourth output pin (number 6~ leads to an open circuit in
25 the illustrated form of the invention, and the final
pulse applied to pin 11 of circuit 174b resets the latch
circuit formed by gates 192 and 194, as does a POR signal
on the POR line 1140
30 It is to be understood that any or all of the fire
zones can be equipped with a volume selector switch
similar to switch 72 such that a larger or smaller
quantity of extinguishant can be applied for each
depression of the corresponding push button switch,
35 depending upon the volume selector switch setting.
Also, any desired number of bottles can be discharged in
either the "full cargo" or "empty cargo" setting of each
volume selector switch.
~.
-
In the event that one of the valves is open and another
push button switch 64-68 or 82-84 is depressed, the
previously open valve closes automatically and the valve
associated with the push button switch opens. For
example, if the cockpit valve 26 is open and a fire
appears in the electrical compartment 14, depression of
the electrical compartment switch 68 closes valve ~6 and
opens valve 38 so that subsequent depression of switch 68
applies all of the discharged extinguishant into the
electrical compartment. When switch 68 is depressed,
the V03 line 122c is energized in the manner described
previously, and, as shown in Fig. 4, operates the valve
latch circuit ~gates 144c and 146c) associated with valve
38, thus opening valve 38. The V03 line 122c (and all
other V0 lines except V06) also connects with line 156
(through amplifier 154c and the associated capacitor 153c)
to apply, through the capacitor, a pulse which forms one
input to NAND gate 158. Unless the crash line 198 is in a
high state, the other input to gate lS8 through inverter
199 is always high, and gate 158 and inverter 160
apply a high pulse to line 162 which is in turn applied to
the RES' line 148 to reset all of the valve latch circuits
(gates 144a-144e and 146a-146e~. This RES' pulse is only
momentary (due to the capacitor 153c) and closes the
previously open cockpit valve 26 and all other
valves. The momentary RES' pulse on line 148 has
disappeared before the electrical campartment switch 68 is
released, and the V03 line 122c is thus energized
subsequent to the RES' pulse in order to open the
electrical compartment valve 38~
In this fashion, depression of any of the push button
switches 64-68 and 82-84 closes all valves except for the
valve associated with the switch that is depressed. If it
35 is desired to open two or more oE the~valves
simultaneously, the corresponding push button switches can
be depressed simultaneously and the desired valves will
open since the RES' pulse will have pa~sed before the push
.
-28-
button switches are released.
The POR line 114 is activated when the system is initially
provided with power or when placed in the test mode. As
shown in Fig. 6, the POR line 11~ resets the bottle
latch circuits formed by gates 222a-222g and 22~a-224g.
Also, the POR line 114 resets the latch circuit fonmed by
gates 192 and 194 (Fig. 5) and connects with the RES' line
1~8 (Fig. 4) to reset the valve latch circuits.
~0
If a crash of the aircraft is imminent, the crash switch
70 can be pushed once to open all valves and again to
discharge all of the extinguishant bottles into all of the
fire ~ones. Depression of switch 70 applies 12 volts to
the V06 line 122f which activates OR gate 139 to apply
power to the AVO bus 140 and the green LED gang line
142. The V06 line 122f connects with the crash line 198
which in turn connects with all of the VO lines 122a-122e,
as shown in Fig. 4. The V06 line thus activates all of
the bottle latch circuits to effect energization of
all of the valve solenoid coils VC1-VC5 and opening of all
valves 26, 30 and 38-42. The holding circuits associated
with the VO1-V05 lines thereafter maintain all valves
open. It is noted that when the crash line 198 is in a
high state, there is a low input to gate 158 through
inverter 199. Once the crash switch is released, the
other input to gate 15~ is low because the capacitors
153a-153e are then fully charged. Consequently, gate 158
does not activate RES' line 148 and the valve latch
circuits are not reset when the crash switch is
pushed .
The V06 line 122f actlvates the latch circuit formed by
gates 144f and 146f and, through the drivers 197,
activates line 196. As shown in Fig. 7, line 196
leads to ground line 128f through the crash lights 126f,
and the crash lights are energized to~light the "ARMED
PUSH TO DISCHARGE" portion of switch 70 a~ter it has been
:
,
- : ,.,~
:
- 29 -
depressed once.
The second depression of crash switch 70 provides a high
signal on line 164f which, in conjunct:ion with the signal
on the CHA' line 124f activates ga te 166f. Decade
counter 174f then applies repeated firing pulses to the
FPG bus 180, and the bottles l9a-19g are detonated in
sequence by the firing pulses in the manner previously
described.
If a crash should occur before there is time or
opportunity to activate the crash switch 70, the impact
switch 246 closes on impact and effects opening of all
valves and detonation of all bottles. Closing of switch
15 246 applies power to line 248 and the crash line
198. All valves are thus immadiately opened by the crash
line as previously described. With reference to Fig. 3,
closing of switch 246 activates the latch circuit formed
by gates 250 and 252 only after the 50micro F capacitor
20 256 has been fully charged. Thus, line 258 is
energized, but only after a time delay sufficient to
assure that all of the valves have been opened. As shown
in Fig. 5, the signal on line 258 passes through inverter
260 and is applied to gate 262. Since all valves are
25 open, the AVO line is in a high state and gate 262
provides repeated firing pulses to the FPG bus 180 each
time the clock line 176 is cycled high. These firing
pulses effect discharge of all of the extinguishant
bottles l9a-19g in sequence, and the extinguishant is
30 directed throughout the aircraft since all valves ar0
open. If there is only time to push switch 70 once before
a crash occurs, the bottles are all discharged in the same
manner.
:
35 It should be understood that extinguishant can be
automatically applied to the aircrat in the same manner
in the event of any other preselected event, such as the
occurrence of a flre ln an aircraft parked on the ground,
:
. -, ~: . ~ , .,
--30--
in addition to a crash. If a fire should occur in the
aircraft, a smoke or heat detector senses the fire and,
after a suitable time delay, automatically effects activa-
tion of the "crash" sequence, thereby discharging all of
5 the bottles into all of the fire zones.
Prior to the takeoff or at any other time, the fire
protection system can be tested by moving the test-reset
toggle switch 60 to the "~est" position. Power is then
10 applied to the test line 270. A reset pulse is
applied to the RES line 110 through amplifier 282 in order
to reset all of the ~alve latch circuits to the idle
stateO Also, a POR pulse is applied through amplifier 284
to the POR line 114 to reset all of the bottle latch
15 circuits.
Test line 270 also energizes relay coils RTl and RT2.
Coil RT2 is available for use in a fire detection system
(not shown). Coil RTl, when energi7ed in the test mode,
20 opens its relay contacts RTl (Fig. 6) so that power
fran the 28 volt bus 88 is unavailable to the bottle
detonator relay contacts RDl-RD7.
Referring again to Fig. 3, the test line 270 applies one
25 input to AND gate 286~ The other input of gate 286 is
low on line 288 unless the bottle latch circuit (gates
222g and 224g) associated with the last or No. 7 bottle
l9g p~ovides a high output to effect detonation of the No.
7 bottle (see Fig. 6). Gate 286 thus normally applies a
30 low input to NAND gate 290, and a high output results
from gate 290 and is applied to input pin 3 of elip flop
circuit 328. The first~output pulse from circult 328 is
applied to output pin 1 and to AND gate 334a. In the idle
condition of circuits 330 and 338, lines 340 and 344 are
35 in the high ~state, and gate 334a thus provides a high
input to gate AND 350a. The other input to gate 350a
comes from the TC line 314.
... . ., ., , .--. ,
. , . ~ .
~ .
.. ;.: ` ' .~
~2~
-31-
The signal on line 314 comes from AND gate 294 which, in
the test mode, has one high input from test line 270 and a
cycllng high/low input frcm the slow (lHz) test clock
circuit 296~ Since line 304 is disconnected from power
due to the opening of the test relay contacts RTl (see
Fig. 6) in the test mode, line 304 is in a low state and
provides a low input to inverter 298 and AND gate 308.
The test line 270 provides a high input to inverter 300
and to gate 308. AND gates 302 and 308 provide low inputs
to NOR gate 306 which applies a high output as the
third input to gate 294. The signal on the TC line 314 is
thus a high/low cycling pulse providing in the low state
an output from gate 350a which, through inverter 352a,
makes transistor 354a conductive to energize the TVOl line
lS 356a. As shown in Fig. 4, the TVOl line 356a connects
with VOl line 122a and causes valve 26 to open as
described previously. Once valve 26 has opened, its
holding circuit established through contact VClA maintains
it open.
The signal applied to inverter 352a is also applied to
line 351a and, through capacitor 172a (Fig. 5) to gate
166a. When the first pulse reaches gate 166a, line L64a
is in a low state since the VOl line 122a is low at that
time. However, when the second pulse reaches gate
166a, line 122a is in a high state (due to the opening of
the first valve) and line 164a is also high. Therefore,
gate 166a is active and activates decade counter 174a
which applies a firing pulse to the FPG bus 180
The initial iring pulse applied to FPG bus 180 in the
test mode activates gate 200 and effects closing of the
RDl contacts. The RTl contacts are open in the test mode,
and the 28 volt bus 88 is disconnected from all of the
RDl-RD7 relay contacts. However, 12 volts is applied
to line 234a through the number 1 amber LED line 242a, and
the circuit is ccmpleted to ground through diode 236a, the
closed RD1 contacts and detonator bridge 232a. The amber
~ED 80a associated with bottle l9a is energized to provide
a visual indication simulating detonation of bottle 19a in
the test mode of operation. Only 12 volts is applied to
bridge 232a and the circuit includes the internal resist
5 ance of LED 80a and the associated 2.2 Kohm resist:or,
so the current passing through bridge 232a is insufficient
to detonate it. However, this method provides a
functional complete check of the entire system as it would
be operated in normal conditions and confirming the
10 ability of each component to perform its intended
funtion.
The subsequent pulses which are generated on line 351a by
the cycling high/low TC line 314 are applied in sequence
15 to circuit L74a since line 164a remains in a high
state due to the constant high state of the VOl line
122a. The resulting pulses which are applied by circuit
174a in sequence to the FPG bus 180 close relay contacts
RD2-RD7 in sequence in the same manner as occurs when one
20 of the push button switches is depressed repeatedly.
Due to the availability of 12 volts through the amber LEDs
80b-80g and the associated lines 242b~242g, circuits are
ccmpleted in sequence through diodes 236b-236g and
contacts RD2-RD7, and the amber LEDs are energized in
25 sequence to simulate detonation of the respective
extinguishant bottles. In each case, insufficient current
passes through the detonation bridges to effect
detonation.
30 When the transistor 2269 associated with the number
seven bottle l9g is energized to simulate detonation of
bottle l9g, line 288 is in a high state, and both inputs
to gate 286 are then high to provide a high input to gate
290. The other input to gate 290 cycles high/low in
35 accordance with the test clock circuit 296, since the
cycling output signal fran gate 294 is applied to inverter
292 which connects with gate 290. The output signal from
gate 290 thus provides a pulse that sets Elip flop circuit
., ......................................... "
:.
.
.
-33~
328 to the next stage o operation.
The output signal from cgate 290 is also applied to NAND
gate 318. Inverter 320 applies a high input to gate 318
which provides a cycling high/low output to amplifier
326~ A high signal is thus applied to the POR line 114
after the capacitor 115 has been charged. The POR signal
on line 114 resets the bottle latch circuits (gates 222a-
222g and 224a-224g) after a time delay sufficient to
charge capacitor 115. The output from gate 318 is
applied to the TC POR line 324 which, without delay,
applies a signal to the RES' line 148 (Fig. 4) through
line 162, and the valve latch circuits (gates 144a-144e
and 146a-146e) are reset before the bottle latch
circuits. All valves are thereby closed prior to
resetting of the bottle latch circuits.
After the valve and bottle latch circuits have been reset
and flip flop circuit 328 has been advanced to the next
stage, the next pulse from circuit 328 is applied to
pin 2 and causes AND gate 334b to provide a high input to
AND gate 350b. The cycling high/low state of the TC line
314 results in an output signal from gate 350b which is
applied through inverter 352b to transistor 354b. The
TVO2 line 256b is then activated, and since it
connects with the V02 line 122b (see Fig. 4), the second
valve 30 is opened and maintained open by its holding
circuit.
The output from gate 350b is also applied to line
351b, which charges capacitor 172b, thus generating a
pulse on one input of gate 166b. Since lines 122b and
164b are inactive at the time of the initial output signal
from gate 350b, both conditions of gate 166b are not
satisfied. The pulse thus opens valve 30 but does not
apply a firing pulse to the FPG bus 180. However, the
next pulse does result in a firing pulse since the V02
line 122b and line 164b are in a high state at the time
:: :
:
~ .
--34--
gate ~66b receives a high signal pulse from 351b. The
signal which is then applied to decade counter 17~b
simulates the detonation of the first bottle l9a in the
manner described previously. Subsequent pulses simulate
detonation of the remaining bottles l9b-19g in
sequence, and the circuitry then resets all valve latch
and bottle latch circuits before opening the ~hird valve
38 and simulating the detonation of bottles 19a-19g in
sequence, resetting, opening the fourth valve 40 and
simulating the detonation of bottles l9a-19g in
sequence, resetting, opening the last valve 42 and
simulating the detonation of bottles l9a-19g and
resetting. The final test valve open line which is the
TV06 line 356f opens all valves via the crash line 198;
and via the V06 line, the latch circuit formed by
gates 144f-146f, and drivers 197 energizes the crash
switch lights in switch 70 via line 196. With the crash
circuit thus "armed" by the test sequence, the next pulse
on line 351f discharges all bottles l9a-19g through gate
166f FPG circuit 174f and 180, and RDl-RD7 as
previously described. Also as previously described, when
bottle latch circuit 222g-224g is active, a high signal is
generated on line 288 which resets all valve and bottle
latch circuits while the flip flop circuit 328-330-338-348
returns to time zero because AND gate 358 decodes the
end of count sequence and generates a re-initializing
pulse via NOR gate 360 and in inverter 362 on line 500.
With the test switch still in test, the next pulse from
gate 290 begins the test sequence again with the first
valve 26.
~loving switch 60 to the "test" position thus gen rates a
test sequence which opens all valves one at a time and
simulates the detonation of all bottles each time a valve
is open~ The crash test is also performed, and the
circuitry resets and cycles automatically through the test
sequence until the test switch 60 is moved to the "off" or
"reset" position. Each valve that opens during the test
. ~
- ^ - ;
, . ,
-' ''' ~ ' ' "'' ;, ' . ' '
.: ; - - ~ ~
sequence effects energi2ation of the corresponding
indicator lights 126a-126e to indicate that the valve has
actually opened, and the crash lights 126f are energized
during the "crash" portion of the test sequence. Each
5 time the test circuitry opens a valve, all 7 green
LED's are indicating -that the current path through each
bottle initiator 232a-232g is operable. The test circuit
then energizes the corresponding amber LED 80a-80g as each
detonate circuit is activated to indicate that the current
10 path through the corresponding detonator circuit is
available if needed to co~nbat a fire. All latch circuits
are reset when the system is taken out of the test mode
since test line 270 then reverts to a low state and a
reset pulse is generated on RES line 110 through inverter
15 272 and amplifier 278 and a POR pulse is generated on
POR line 114 through inverter 272 and amplifier 276.
As previously indicated, gate 306 provides a high output
in the test mode. Inverter 310 thus provides a low input
20 to gate 312, and the other input signal is the
high/low cycling output from gate 2947 The result is that
line 316 is cycled between high and low states.
Consequently, the amber light 62 on the control panel
flashes on and off to provide a visual indication that the
25 system is operating in the test mode.
If the system is placed in the test mode of operation and
the test relay for some reason malfunctions and fails to
open the test relay contacts RT1, the amber light 62 is
30 constantly on to indicate the presence of a fault in
the system. If the RTl contacts remain closed, line 304
~Fig. 6) is in a high state since it is di~ectly connected
with the 28 volt power bus 88. As shown in Fig. 3, line
304 connects with inverter 298 which then provides a low
35 input to gate 302, resulting in a low input to gate
3G6. The other input to gate 306 comes from gate 30~ and
is high because lines 270 and 304 are both in a high
state. The~output from ga-te 306 is thus 1GW~ and the
,. ~ . - : , ; :
' ~
` ~ ``: " ~:
--36--
output frcm inverter 310 is high to provide a low output
on line 316 from ga-te 312. Since the opposite side of the
amber light 62 is connected with +12 vo~ts, light 62 is
steadily energized when line 316 is in a constant low
5 state, and the light visually indicates that there is
a fault in the system. Also, the low output of gate 306
is connected to yate 294. This prevents passage of the
test pulse from clock 296 and thus stops the test sequence
to prevent inadvertent discharge of bottles l9a-19g.
Another potential fault condition exis-ts if the system is
out of the test mode but 28 volts is not available to the
bottle detonator circuits, due to the failure of the test
relay contacts RTl to close or for any other reason. The
15 amber light 62 again is energized constantly in this
situation to indicate the presence of a fault condition.
The lack of power to line 304 places it in a low state,
and inverter 298 provides a high input to gate 302. The
other input to gate 302 canes from inverter 300 and is
20 also high since the test line 270 is in a low state.
Gate 302 thus provides a high signal to gate 306 which in
turn provides a low input to the inverter 310. The
resulting high input to gate 312 places line 316 in a
constantly low state and energizes light 62 to provide a
25 steady visual indication of the fault so that
corrective measures can be taken.
It is thus apparent that the fire protection system
permits extinguishant material to be applied in the
30 necessary quantity to extin~uish a fire in any of the
fire zones of the aircraft, and that the extins~uishant i5
directed to the appropriate location through the valves
which are accurately controlled by the circuitry and
opened before the extinguishant bottles are detonated. At
35 the same time, all of the controls are conveniently
located on the control panel 54~ and only one swi~ch must
be depressed to extinguish a fire in any one fire ~one.
The "ARMED" indicator lights that are built into the push
,
:
.
!
-37-
button switches indicate the status of each valve, and the
bottle lights 78a-78g and 80a-80g indicate the status or
availability of the individual extinguishant bottles ~9a-
199 .
The test circuitry is operated as easily as the controls
which actually apply extinguishant to a fire, and the
simplicity of the test procedure increases the likelihood
that the system will be tested frequently to enhance its
reliability. The test mode requires only that a
single switch (62) be moved and results in an easily
obseLved indication that the system is in test, that each
valve is actually opened, and that each bottle detonator
circuit and the bottles are in working condition.
The test circuitry also displays faults in the control
panel, and it s lamps, valves, bottles and computer
module. The lamps are visually inspected as the test
se~uence operates. A valve that fails to open is shown by
the corresponding control panel switch "armed" light
flashing on and off as the test pulses attempt to activate
the failed valve. A valve that is stuck open when
deenergized displays a steady "armed" light in its
corresponding central panel switch. A faulty bottle is
shown by its corresponding green LED not being
illuminated at the time any valve is open but its
corresponding amber LED illuminating in se~uence by the
test circuit. An empty bottle is shown by the
corresponding amber LED being on at all time and the
corresponded green LED failing to illuminate when any
valve is opened. A computer module fault with the test
relay is shown by the flashing amber LED becomi~ steady,
and if in "test" the test sequence stops~
Figs. 9 and 10 depict an alternative form of the
invention which is in many respects similar to the
embodiment described previously. Components in the second
embodiment that are identical to or similar to components
..
`': ''' : : ~ ;' , ' . , , ~
.
~2~3~
-38-
found in the first embodiment are referred to by the same
numerals in Figs. 9 and 10 as are used in Figs. 1-~.
The embodiment of Figs. 9 and 10 is simpliied somewhat
and is intended for use in an aircraft having only a
small number of fire zones such as three, for example,
namely a left engine compartment (engine No. 1), a right
engine compartment (engine No. 2) and a cabin area. As
shown in E~ig. 9, only five bottles of extinguishant
material (19a-19e) are provided in the aircraft,
although a greater or smaller number of bottles is
possible. The bottles connect with a common manifold line
22 which leads to the inlet port of a three way solenoid
valve 500 (valve No. 1). When the coil of valve 500 is
deenergized, the deenergized port (DE) is connected
with the inlet port, and inccming extinguishant is
directed into the cabin of the aircraft. The energized
port (E) of valve 500 connects with a line 502 leading to
the inlet port of another three way solenoid valve 504
(valve No. 2). The deenergized port (DE) of valve 504
applies extinguishant to the left engine compartment, and
the energized port (E) applies extinguishant to the right
engine compartment.
In this manner, the two three way valves 500 and 504
control the flow of extinguishant to three fire zones. It
should be pointed out that the system of Figs. 9 and 10
can also be employed~with two way valves. In this case,
as will be explained more fully, each fire zone has a two
way valve connected with the common manifold line
22. Components that are not present when~three way valves
are used are enclosed by broken lines and components ~hat
are not present when ~wo way valves are used are enclosed
by solid lines.
Referring now to Fig. lOa, the fire protection system
includes a power supply of the same type described
previously, and the same reference numerals are used in
`: :
-39-
Fig lOa to designate similar c~mponents. Each fire zone
has a push button switch similar to those shown in Fig. 2
and associated circuitry similar to that of Fig. 7. Thus,
when the respective push button switches are depressed, a
Vo-l line 122a, a V0-2 line 122b and a VO-cabin line
122c are provided with power (see Fig. lOd). With
continued reference to Fig. lOd, the VO-l line 122a leads
to a valve latch circuit formed by gates 144a and 146a,
and the V0-2 line 122b connects with a valve latch circuit
~0 formed by gates 144b and 146b The VO-cabin line 122c
connects with a three input AND gate 506 having on its
output line inverter amplifiers 508 and 510 which connect
with a valve latch circuit formed by gates 144c and
146c. The other two inputs to gate 506 are on valve idle
lines 542 and 544 (VIDL-l and VIDL-2) that are
energized when the respective valves 500 and 504 are idle
or deene~ized. The ccmponents within the solid box 511
are omitted if two way valves are employed rather than
three way valves.
As shown in Figs. lOa and lOd, the VO-l line leads to a
junction 512 which connects through a 4.7 mf capa~itor 514
with an amplifier 516 applying its output to the RES' line
148. Similar, the V0-2 line leads to a junction 518 which
connects with the RES' line 148 through a capacitor
520 and an amplifier 522. A junction 524 connected with
the VO-cabin line connects with line 148 through a
capacitor 526 and an amplifier 528.
When the No. 1 valve 500 is energized, a high signal
is applied to a VO-lL line 530 which connects with
junction 512 through a diode 532 and a normally closed
relay contact RV-2B (which is omitted when two way valves
are employed, as indicated by box 533). A V0-2L line 534
is energized when the No. 2 valve 504 is energized.
Line 534 connects with junction 518 through a diode 536.
A V0-3L line 538 which is energized when both valves 500
and 504 are deenergized connects with junction 524 through
. . . .
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, . .
--40--
a diode 540~ As indicated by box 541, diode 540 is
replaced by a jumper when two way valves are used. The
VO-lL, V0-2L and V0-3L lines provide holding circuits for
the valve latches in substantially the same manner
S described previously in connection with the first
embodiment of the invention,
Fig. lOe illustrates the transistors 150a and 150b which
energize the relay coils RV-l and RV 2 having the
10 corresponding contacts which canpl~ete the VC-l and VC-
2 lines, respectively. The VC-l and VC-2 lines energize
valves 500 and 504, respectively. The RV-3 relay and VC-3
line are not present when three way valves are used, as
shown by the dashed box 542, although they are used when
15 two way valves are e,mployed, as will be explained more
fully, The emitter of transistor 150c connects with the
CAL (cabin light) line 543 which lights the "ARMED" half
of the cabin switch when energized.
20 Fig. lOb illustrates the latch circuits formed by
gates 168a and 170a, 168b and 170b and 168c and 170c that
connect with the left engine LE-A and LE-A' lines 118a and
124a, the right engine RE-A and RE-A' lines 118b and 124b
and the cabin C~-A and CA-A' lines 118c and 124c,
25 respectively,
As previously described, when the corresjponding push
button is depressedl these latches apply pulses to gates
166a-166c through capacitors 172a-172c. The other inputs
30 to gates 166a-166c are applied on the valve latch
output lines 164a-164c which are tied to ground via the
capacitors 165a-165c. Gates 166a-166c connect with
respective circuits 174a-174c receiving clock inputs on
line 176 from the firing pulse clock circuit 178. The
35 output pulses fram circuits ~174a-174c are appIied to
the FPG bus 180. A three input AND gate 545 (not present
if three way valves are used) connects on its output ~side
with FPG bus 180 and on i~ts input side with lines 140, 176
. . . : ,
-~
--41-
and 581.
The firing pulses which detonate the extinguishant bottles
are generated somewhat differently in the Figs~ 9 and 10
5 system~ Referring to Fig. 10c, the pulses applied to
the FPG bus 180 are applied to the clock input of a bottle
se~uence counter circuit (BSC) 546 having its clock
inhibit input tied to an AVO line 548. The AVO (an
inverted active AVO) signal canes fran ~he AVO (any valve
10 open) bus 140 through an inverter 550 (Fig. 10h). The
reset pin of circuit 546 is tied to an AND gate 551
receiving inputs from the POR line 114 and from the output
line 222a.
15 When the AVO line is low (high AVO), the bottle
sequ~nce counter 546 responds to the pulses on the FPG
line 180 and applies output pulses in sequence to bottle
latch circuits formed by the gate pairs 222a and 224a-222e
and 224e. As shown in Figs. 10c and 10f together, the
20 bottle latch circuits in turn activate transistors
226a-226e to energize the detonator relay coils RDl-RD5,
thus closing the associated relay contacts RDl-RD5 to
apply 28 volts to the detonators of the respective bottles
l9a-19e through the normally closed RTl relay contacts,
25 all as described previously.
Referring now to Figs. 10d and 10e, the output line from
the No. 1 valve latch circuit is applied through a diode
to the ~VO bus 140 which also connects through an ampli
30 fier 552 and diode 554 to the green LED gang line 142
(AVO-GREEN LEDS). The output lines from the No. 1 and No.
2 valve latch circuits connect with the input lines of an
AND gate 556 having its output line tied to the; base of a
transistor 558. When transistor 5S8 i~s active, it
35 energizes the RV-2B relay coil which opens the RV-2B
contact in the VO-lL line 530. The output line of the No.
2 valve latch circuit is tied through a diode 560 with the
output line of the No. 1 valve latch circuit. The
.
,
: ~ '' ' :
-42-
components within the box 562 are omitted when two way
valves are used in the fire protection system.
When the crash push button (not shown) is depressed, a
high signal is applied to the CRASH-~' line 564 and to
a latch circuit 566 formed by two NOR gates (Fig. lOd).
The CRASH-A line 568 provides one input to the lower
gate. The output from latch 566 connects through a
capacitor 570 with a NAND gate 572 receiving its other
input from the VO-lL line 530. The second input to
gate 572 is grounded by a 4.7 mf capacitor 573. ~fter
being inverted at 574, the output from gate 572 is applied
to a latch circuit 576 having another input on the reset
line llO. The output from latch 576 is on line 578 which
is connected to the clock inhibit input of a crash and
test sequence counter circuit 580 (Fig. lOe). The second
output from latch 576 is on line 581 which is not used if
three way valves are employed in the system.
Also connected with the input of latch 576 is one
output line of another latch circuit 582 having an
inverter 584. A grounded capacitor 585 is connected
between inverter 584 and latch 576. The other output from
latch 582 is on line 586 which is not present when three
way valves are used, as indicated by box 588. The
inputs to latch 582 are on the RES' line and on line 590
which goes high when the gravity or impact switch (not
shown) closes upon crash of the aircraft. A capacitor 591
connects line 590 to ground to assure that latch 582 will
be activated only by an ac~ual crash and not by
momentary closing of the impact switch.
The CRASH-A' line 564 and the output line of inverter 584
connect with one input of a latch circuit 592 having the
RES' line 148 tied to its other input. The output
from latch 592 is applied through an inverter 594 to the
crash switch light line 196 which lights the "ARMED" half
of the crash switch as previously explained. The ou~put
~ r ,~ ?~
:
.
-43-
from inverter 594 is also applied through respective
diodes 596, 598 and 600 to the VO-lL, V0~2L and V0-3L
lines 530, 534 and 538. Diodes 598 and 600 are eliminated
when two way valves are used.
A test clock circuit 602 (Fig. lOg) applies clock pulses
to a test clock line 504 which is tied to the clock input
of the crash and test sequence counter 580, as shown in
Fig. lOe. The test clock pulses are at times absorbed by
a pair of flip flop circuits 606 and 608. Line 604 is
connected through diodes 610 and 612 with the Q output
pins of the respective circuits 606 and 608. The reset
pins R of circuits 606 and 608 are connected with lines
614 and 616 which, as shown in Fig. lOcl are activated by
transistors 618 and 620 when the respective RDl and
RD2 relay contacts close to detonate the No. 1 and No. 2
bottles.
The application of test clock pulses to circuit 580
results in sequential output pulses 1-9 therefrom.
The initial pulse reaches the VO-l line. The second pulse
is applied through a diode 622 to the FPG bus 180. The
second pulse is also applied to line 624 which connects
with one input to an AND gate 626 and with the clock input
of circuit 606. The other input to gate 626 comes
from the VO-lL line 530 through an inverter 628. The
output from gate 626 is applied through diode 630 to a
line 632 connecting with the pin of circuit 580 on which
the eighth pulse appears. Line 632 provides one input to
a three input AND gate 634 having its other input pins
tied to the FPG clock line 176 and the AVO line 140. The
output signal from gate 634 is transmitted to the FPG bus
180 through a diode 636.
The third output pulse from circuit 580 is applied to
the RES' line 148, as is the sixth pulse. The fourth
pulse appears on the V0-2 line. The fifth pulse is
applied through a diode 638 to the FPG bus 180 and,
. - ,
.
-44-
upstream of the diode, to an ~ND gate 640 and the clock
input to circuit 608. The other input to gate 640 comes
from the V0-2L line 534 through an inverter 64~. The
output from gate 640 is applied through diode 644 to line
632. The seventh pulse frcm circuit 580 appears on
line 538, the eighth pulse appears on line 632, and the
ninth and final pulse is applied to the clock inhibit pin.
Referring now to Fig. 10g, the test line 270 which is
energized upon activation of the test switch is
connected to one input of a NAND gate 648. The second
input to gate 648 comes on the 28 volt line 649 to which
+28 volts is applied through the RTl relay contacts. Gate
648 is arran3ed with another NAND gate 650 to provide an
inc~usive OR gate generally indicated at 652. The
output line 654 of the inclusive OR gate 652 connec~s with
a fault line 656 through a pair of inverters 658 and
660. The fault line connects with ground through an LED
662. A NAND gate 664 receives inputs on lines 270 and 604
and provides its output to an inverter 666 which in
turn provides its output to line 654.
The test line 270 connects with a conductor 668 extending
between lines 614 and 616, as shown in Fig. 10e. Line 668
has a pair o~ diodes 670 and 672 on opposite sides of
its junction with line 270.
The fire protection system shown in Figs. 9 and 10 is
placed in operating condition by closing the circuit
breaker (not shown) that connects the power supply
with the 28 volt lines 86 and 88. The voltage regulator
then provides power for the 12 volt bus 102 and applies a
reset pulse on the RES line 110 through capacitor 108 and
amplifier ~06 and a POR pulse on line 11~ through
capacitor 108 and amplifier 112. Again, the RES and
POR pulses that pass through capacitor 108 generate a
signal on RES' line 1~8 (Fig. ~ which resets the valve
latch circuits.
. .
,
.
.. . ~ , .
-45-
In operation of the fire protection system, a fire in any
of the designated Eire ~ones is either detected by a
suitable detection system or is sensed by the pilot of the
aircraft or other personnel. In the event of a fire in
the left engine compartment, for example, the left
engine switch is pushed once to arm the system by opening
valve 500 and is pushed subsequently one or more times to
discharge one or more of the extinguishant bottles in
order to apply extinguishant to the left engine
compartment.
Depression of the left engine switch applies +~2 volts to
the VOl line 122a and lights the "ARMED" half of the
switch in the manner indicated previously. The VO1 line
connects via junction 512 with capacitor 514 and
amplifier 516 ~o apply a pulse to ~he RES' line 148 which
resets all valve latch circuits. The VOl line 122a also
applies power to the latch circuit formed by gates 144a
and 146a. Although this latch circuit receives the reset
pulse, the push button switch remains depressed after
the reset pulse has disappeared. The high output from the
No. 1 valve latch circuit IS applied to the base of
transistor 150a to make the transistor conductive. Relay
coil RVl is thereby energized, a:nd the RVl relay contacts
connect +28 volts with the VCl line to effect opening
of the No. 1 valve 500.
.
When the No. 1 valve is energized, +12 volts is applied to
the VO-lL line 530 which in turn connects with the VO1
line 122a throuyh the normally closed relay contacts
RV-2B. This completes the holding circuit which bypasses
the left engine switch and thereafter maintains valve 500
open when the left engine switch is released following its
initial depression. The holding circuit maintains power
on the VO1 and VC1 lines until the RES' line 148~is
eneryized to reset the latch circu~it formed by gates 144a
and 146a. ~ ~ ~
~2~
--46--
The high output frcm the No. 1 valve latch circuit is
applied to the AVO bus 140 and through amplifier 552 and
diode 554 to the green LED gang line 142. A current path
to ground is then completed ~hrough the green LEDs and the
5 bottle detonator circuits. If any o the
extinguishant bottles has been used, its detonator bridge
will be broken to break the circuit that would otherwise
energize the corresponding green LED. Thus, the green
LEDs that are energized on the control panel indicate
10 which bottles are available, and the absence of a
green light for a particular bottle indicates that such
bottle has already been used and is unavailable, all as
described previously. Again, the curren-~ passing through
the detonator bridges is relatively small and is
15 insufficient to detonate the bridges.
Depression of the left engine switch applies 12 volts to
the LEA' line (designated 124a in Fig. lOb), and the
signal on line 124a is applied to gate 170a to activate
20 the associated latch circuit. A pulse is thereby
applied momentarily through capacitor 172a to gate 166a.
The capacitor 172a quickly becomes charged, and the high
input signal to gate 166a is then removed since current no
longer passes through the charged capacitor. The other
25 input to gate 166a comes from the valve latch circuit
via line 164a and is delayed until capacitor 165a (Fig.
lOe) is ully charged. Due to the relatively large
capacitance of capacitor 165a (4.7 micro F) compared to
that of capacitor 172a (.002 micro F) the momentary high
30 signal applied to gate 166a through capacitor 172a is
no longer present when the high signal on line 164a
reaches the other input of gate 166a. Consequently, there
is no output generated from gate 166a upon initial
depression of the left engine switch, and decade counter
35 174a remains inactive and does not apply a firing
pulse to the FPG bus 18~.
However, when the left engine swltch is depressed a second
.
, . ~
,
., . : ~:
,: , : : :
:, ~: .
--47--
time, the LEA' line 124a is once again energized and a
second momentar~ high signal is applied to gate 166a
through capacitor 172a. Since the holding circuit
continuously maintains the VOl line 122a in a high state,
line 164a remains continuously high, and gate 166a
receives two high inputs the second time the left engine
switch is depressed. The resultiny pulse applied to
decade counter 174a generates an output pulse which is
applied to the F~G bus 180 and to the clock input of the
bottle sequence counter 546 (Fig. lOc).
At this time, the AV0 bus 140 is in a high state and the
AVO line 548 provides a low signal to the clock inhibit
input of circuit 546. The output pulse which is applied
to the bottle latch circuit fonned by gates 222a and
224a activates the latch and transistor 226a, thereby
making the transistor conductive and energizing relay coil
RDl. The associated relay contacts RDl then canple te the
28 volt circuit through the detonator bridge of the number
one bottle l9a. Extinguishant is directed frc~n the
detonated bottle through the energized valve 500 and out
the deenergized port of valve 504 to the left engine
compartment of the aircraft.
If one bottle of extinguishant is insufficient to
control the fire, the left engine switch can be depressed
repeatedly to discharge a subsequent bottle for each
subsequent depression of the switch, due to the sequentlal
pulses applied by circuit 546 to the successive bottle
latch circuits. As previously described, the
associated detonator bridge is destroyed each time a
bottle is discharged, and the path to ground through the
corresponding green LED is interrupted. Each time a
bottle is discharged, the corresponding pressure switch
closes due to the pressure drop in the bottle. This
completes a circuit path to ground for the corresponding
amber LED. Consequently, each bottle that is discharged
results in energization of the associated amber LED and
:
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. ~ ~ - `; ` ~ .
, .
-48-
deenergization of the associated green LED to provide a
visual indication that the bottle has been discharged and
is no longer available.
It is to be understood that any or all of the fire
zones can be equipped with a volume selector switch
similar to the switch 72 described in connection with the
first fOL~ of the invention. Also, any desired number of
bottles can be discharged in either the "full cargo" or
"empty cargo" setting of each volume selector
switch. It should be further noted that one or more
additional output lines of circuits 174a-174c can be
connected with the FPG line 180 such that two or more
bottles will be detonated due to the sequential pulses
applied to the FPG line for each switch depression
after the first.
In the event of a fire in the right engine ccmpartment,
the right engine switch is depressed to apply power to the
V02 line 122bc The path through junction 518,
capacitor 520 and amplifier 522 effects a momentary pulse
on the RES' line 114 to reset all valve latches. The V02
line connects with the No. 2 valve latch formed by gates
144b and 146b to activate transistor 150b and relay RV-2,
thus energizing the VC 2 line to energize the solenoid
of the No. 2 valve 504. The output signal from the No. 2
valve latch circuit is also applied through dibde 560 to
transistor 150a (see Fig. lOe~, and the No. 1 valve is
thereby energized while in effect bypassing its valve
latch circuit (gates 144a and 146a).
In this manner, depression of the right engine switch
energizes both valves 500 and 504 to provide an
extinguishant path to the right engine compartment. The
energizing of valve 504 makes the VO-2L line 534 high
to provide a holding circuit for the No. 2 valve latch
circuit (gates 144b and 146b) after the right engine
switch is released. ~Although the VO-lL line 530 is in a
- , : :: :
:,
.
.
L~
--D,9--
high state due to energizing of the No. 1 valve 500, the
relay contact RV-2B is now open to prevent activation of
the No. 1 valve latch circuit. The output signal from the
No. 2 valve latch circuit is applied to the lower input of
gate 556 and also to its upper input via diode 560.
Transistor 558 is then made conductive by gate 556 to
ene~ize the ~V-2B relay coil, thus opening the normally
closed RV-2B contact in line 530.
Once both valves 500 and 504 have been energized,
subsequent depressions of the right engine switch provide
high signals on the REA' line (designated 124b), and
circuit 174b provides firing pulses to the FPG bus 180 to
detonate a bottle for each depression of the switch in the
manner described earlier. The AVO line 140 goes high
when the No. 2 valve latch circuit is activated and only
remains high if the No. 2 valve has actually moved when
energized, and the AVO line 548 is thus low to avoid
inhibiting the bottle sequence counter 546. The green LED
line 142 provides power to energize the green LEDS of
available bottles.
If there is a fire in the cabin, the cabin switch is
depressed to energize the VO-cabin line 122c. Junction
524, capacitor 526 and amplifier 528 provide a circuit
path to the RES' line 148 such that a reset pulse resets
all valve latch circuits. Diode 540 isolates junction 524
from the No. 3 valve latch circuit formed by gates 144c
and 146c~ If both valves 500 and 504 are deenergized as
they should be by the reset pulse, the valve idle
lines 542 and 544 provide high input signals to g~ate
506. Since the VO-cabin line 122c remains high while the
cabin switch remains depressed, gate 506 is active to
activate the "No. 3" valve latch circuit (gates 144c and
146c) via amplifiers 508 and 510 and l1ne 538. ~
The output signal from the No. 3 valve latch makes
transistor 150c conductive to apply power to the CAL line
:
- . . ~, ~ ' . . ~,, ,
' `' ';;~ ~' ' , ;
,.. :
-50-
543 which lights the "ARMED" half of the cabin switch.
Also, line 164c is energized to permit bottle detonation
when the cabin switch is subsequently depressed Line 609
provides a "false" AVO signal to the AVO line 140 even
though both valves 500 and 504 are actually
deenergized. The V0-3L line 53~ provides a holding
circuit to maintain the No. 3 valve latch circuit
activated after -the cabin switch has been released.
When the cabin switch is depressed again, the CA-A'
line (designated 124c) goes high to detonate the first
available bottle via circuit 174c and the bottle sequence
counter 546 as previously described. Since both valves
500 and 504 are deenergized, the extinguishant is directed
into the cabin of the aircraft through the deenergized
port of valve 500. It should be pointed out that unless
the AVO line 140 is energized (due to energizing of one or
both of the valves 500 and S04 or due to the "false" AVO
signal on line 609) the AVO line 548 will be high to
inhibit circuit 546 and thereby prevent the detonation
of any bottles.
When the crash switch is depressed, the crash-~' line 564
is energized to activate latch circuit 592 (see Fig.
lOg). The low output signal from latch 592 is
inverted by the inverter 594 and applied through diode 596
to the VO-lL line 530 and through diode 532 and the RV-2B
relay contact to the VOl line, thereby activating the No.
l valve latch circuit to effect energizing of valve 500.
The holding circuit provided by the VO-lL line 530
thereafter holds valve 500 open. The output from inverter
594 is also applied to line 196 to light the "~MED" half
o~ the crash switch.
The crash-A' line 564 also activates latch 566 (Fig.
lOd) to apply a momentary pulse through capacitor 570 to
gate 572. However, capacitor 573 delays the pulse which
is applied from line SiO to ~he other input of gate 572,
" ` :
:. . :
-5~-
and by the time capacitor 573 is charged, the pulse
applied through capacitor 570 has disappeared. Thus, gate
572 is not activated upon initial depression of the crash
switch.
The second depression of the crash switch does activate
gate 572 because capacitor 573 is fully charged when the
second pulse frcm capacitor 570 reaches gate 572. Then,
the high output provided by inverter 574 activates latch
circuit 576, and its low output on line 578 goes to
the clock inhibit input of the crash and test sequence
counter circuit 580, thus pe~mitting circuit 580 to
respond to the clock pulses applied on line 604 by the
test clock 602 (Fig. lOg). Prior to the second depression
of the crash switch, line 578 is high to inhibit
circuit 580.
The first pulse frcm circuit 5B0 goes to the VO-l line
which is already energized. The second pulse is applied
through diode 622 to the FPG bus 180 and to the bottle
sequence counter 546 (Fig. lOc). Circuit 546 then
detonates the No. 1 bottle in the usual manner, and its
contents are applied to the left engine compartmentO The
resultant activation of transistor 618 provide~ a reset
pulse on line 614 to fIip flop circuit 606. Delay of
this reset pulse can be effected in any desired manner.
Prior to thus being reset, the Q output of circuit 606 was
low due to the input on its clock pin from line 624.
Consequently, circuit 606 is reset to permit the clock
pulses on line 604 to pass only after detonation of
the bottle.
The third pulse fron circuit 580 resets all valve latches,
and the fourth pulse goes to the V0-2 line to energize
both valves 500 and 504. The fifth pulse goes to the
FPG line 180 to detonate another bottle and discharge its
contents to the right~engine compartment. The fifth pulse
is also applied to the clock input of circuit 608, making
:
: :
--52--
its Q output low to prevent passage of subsequent clock
pulses on line 604 until circuit 608 is reset by the
delayed reset pulse that appears on line 616 due to
activation of transistor 620 when the extinguishant bottle
5 is detonated.
The seventh pulse frcm circuit 580 is applied to line 538
to activate the "No. 3" valve latch circuit, thus
deenergizing both valves 500 and 504 and generating a
10 "false" AVO signal on line 140. The eighth pulse goes
to gate 634 which, since the AVO lin0 140 is high,
provides output pulses under the control of the cycling
FP& clock line 176. These output pulses pass through
diode 636 to the FPG bus 180 and effect detonation of the
15 remaining bottles in sequence into the cabin. The
ninth and final pulse goes to the clock inhibit input to
circuit 580 to teL~ninate its cycle. It should be
understood that the crash sequence can be modified to
apply extinguishant in any desired quantity to the fire
20 zones in any desired sequence.
In the event of a malfunction resulting in the failure of
the No. 1 valve 500 to properly open, the signal applied
to inverter 628 on the VO-lL line 530 is low since the No.
25 1 valve did not actually open, gate 626 then receives
a high signal fram inverter 628 and another high input on
line 624 when the second output pulse is generated by
c ircuit 580. Gate 626 then applies a high input through
diode 630 to gate 634. The AVO line 140 is high since the
30 No. 1 valve latch circuit is activated even though the
valve did not open, and gate 634 then provides output
pulses in sequence with the FPG clock line signals. The
bottles are thereby detonated in sequence and are all
discharged into the cabin.
If the ~o. 2 valve 504 should malfunction and Eail to open
in response to the fourth output pulse from circuit 580,
the V0-2L line 534 remains low and the holding circuit it
~, ~
-53-
is intended to provide for the No. 2 valve latch is not
completed. As a result, the No. 2 valve latch is
deactivated as soon as the fourth pulse from circuit 580
passes, and the No. 1 valve is no longer held energized by
the No. 2 valve latch circuit~ Thus, when the fifth
pulse from circuit 580 appears, both valves are
deenergized. The fifth pulse provides one input to gate
640, and the other input is provided as a high signal from
inverter 642 and the low V0-2L line 534
~he output from gate 640 passes through diode 644 to gate
634. The input on the AVO line 140 is high because the
capacitor 691 has not yet discharged fully, and gate 634
thus provides output pulses to the FPG bus in sequence
with the FPG clock line 176. Consequently, all
remaining bottles are discharged into the cabin. In this
manner, a malfunction in either valve 500 or 504 advances
the crash system to the cabin and effects discharge of all
remaining bottles into the cabin area of the aircraft.
In the event of a crash of the aircraft, the impact switch
(not shown) closes to energize line 590 (Fig. lOd) once
capacitor 591 is charged~ Latch 582 is then activated and
provides a low input to inverter 584 which is transmitted
as a high signal through diode 697 to latch 592 (Fig.
lOg). Activation of latch 592 provides a high signal from
its inverter 594 which lights the crash switch lights via
line 196 and energizes the VO-lL line 530 through diode
596. This energizes the No. 1 valve 500 via the VOl line
and the No. 1 valve latch circuit.
The high output from inverter 584 reaches latch circuit
576 only after a time delay provided by capacitor 585
suficient to allow the No. l valve to open. Then, latch
576 is activated to provide a low signal on line 578
which is applied to the clock inhibit input pin of the
crash and test sequence counter 580. Circuit 580 is then
placed in operation to respond to the test clock pulses in
`` : : :
:` ~ .;
~z~
--54--
the manner previously described. ~gain, a malfunction in
either valve results in discharge of the remaining
extinguishant bottles into the cabin of the aircraft.
Testing of the fire protection system is initiated by
activating the test switch to energize the test line
270, As shown in Fig. 10a, this provides pulses on the
reset line 110r the reset' line 148 and the POR line 114
to reset all valve and bottle latches. Also, line 270
energizes the RTL test relay coil to open the RTl
contacts (Fig. 10c), thus removing the 28 volt power from
the bottle detonator circuits to prevent actual detonation
of any bottles in the test mode. Lines 244a 244e provide
small amperage current to the bottle detonator circuits as
indicated in connection with the first embodiment of
the invention.
The test line 270 connects with line 668 between diodes
670 and 672, as shown in Fig. 10e. The test line thus
resets the flip flop circuits 606 and 608 on lines 614
and 616 to make their Q outputs high. Test clock pulses
on line 604 are then allowed to pass circuits 606 and 608
to the clock input of circuit 580 which provides pulses 1-
9. The lights on the control panel indicate that the
system is in good operating condition. The test
sequence teL-minates with the ninth pulse which goes to the
clock inhibit pin of circuit 580. As in the first
embodiment, the low level current applied to the bottle
detonator circuits is insufficient to cause actual
detonation but does provide an indication of the
ability of the system to detonate bottles in the event of
a fire.
In the test mode, 28 volt power is normally removed from
line 649 (Fig. 10g), and the inclusive OR gate circuit
652 receives one high input on the test line 270 and one
low input on line 649, making the output line 654 low.
Consequently, the test clock 602 Fycles the output fr~m
- . "
., :
--55--
gate 664 high and low, and the cycling signal is applied
through inverters 658 and 660 to cause LED 662 to flash,
thus indica.ing that the system is in the test mode. When
the system is out of the test mode, line 649 is high and
line 270 is low, so the inclusive OR gate 652 and NAND
gate 664 both provide low outputs to the LED 662.
If a fault should occur in the test mode causing a failure
to remove 28 volt power fran line 649, both lines 270 and
10 649 are energized, and the inclusive OR gate output is
a constant high which energizes LED 662 constantly. Also,
the BSC 546 is inhibited, thus preventing the test
seguence from continuing and thereby preventing the
discharge of bottles. This inhibit signal is generated by
15 the output of NAND gate 648 via line 548. Conversely,
if there is a failure to return 28 volts to line 649 when
the system is taken out of the test mode, lines 270 and
649 are both low to provide a constant high output from
the inclusive OR gate 652. Again, the LED 662 is on
20 constantly. In this fashion, LED 662 provides a
visual indication in the event of fault in the system.
If two way valves are used in the fire protection system
rather than three way valves, there are three valves
~5 present, one for each engine caflpartment and one for
the cabin. The bottles connect with each valve.
Activation of the No. 1 valve latch circuit opens the left
engine valve, and activation of the No. 2 valve latch
circuit opens only the right engine valve (No. 2 valve)
30 since AND gate 556 and the RV-2B relay are now
eliminated along with the connecting line containing diode
560. The VO-cabin line 122c connects directly with line
538 and the No. 3 valve latch circuit since diode 540 is
replaced by a jumper.
The bottle detonation is accanplished in the same manner
described previously, and the test system and ~ault
indication are likewise the same. Initial depression of
- , . , . ~ .
~; '
--56--
the crash switch activates gate 592 immediately to provide
high signals to the VO-l, VO-2 and VO-cabin lines through
diodes 596, 598 and 600. ~11 three valves are then
opened. The next depression of the crash switch activates
5 latch 566 and, since capacitor 573 is now fully
charged, activates gate 572 and latch 576. The high
signal on line 581 activates gate S45 (Fig. lOb) which
provides firing pulses to the FPG bus 180 in sequence with
the pulses from the FPG clock 178. These pulses cause the
10 bottle sequence counter circuit 546 to detonate all
bottles in sequence, and the extinguishant is applied
through all three open valves to the three fire ~ones of
the aircraft. Sequence counter circuit 580 is inhibited
by the high input applied on line 581 to its clock inhibit
15 pin and is thus prevented fr~n resetting any of the
valve latches.
Energization of the impact switch line 590 activates latch
582 and, through diode 697, immediately activates latch
20 592 to open all valves as previously describedO After
a time delay sufficient to fully charge capacitor 585,
latch 576 is activated to effect detonation of all bottles
via gate 545, also as described previously~ Again, line
581 inhibits circuit 580 to prevent it from resetting the
25 valve latches.
Fr(m the foregoing, it will be seen that this invention is
one well adapted to attain all the ends and objects
hereinabove set forth together with other advantages which
30 are obvious and which are inherent to the structure.
It will be understood that certain features and
subcombinations are of utility and may be ernployed without
reference to other features and subcanbinations. This is
35 contemplated by and is within the scope of the claims.
~3ince many possible embodiments may be made of the
invention without departing from the scope thereof, it is
..
., :
-57-
to be understood that all matter herein set forth or shown
in the accompanying drawings is to be interpreted as
illustrative and not in a limiting sense.
: ` : :: : ~ ~:
