U.S. patent application number 13/279792 was filed with the patent office on 2014-03-06 for thermal management of a propulsion circuit in an electromagnetic munition launcher.
This patent application is currently assigned to LOCKHEED MARTIN CORPORATION. The applicant listed for this patent is Matthew Aubuchon, Mandel Floyd, Ronald J. Kaye, David Lewis Smith. Invention is credited to Matthew Aubuchon, Mandel Floyd, Ronald J. Kaye, David Lewis Smith.
Application Number | 20140060508 13/279792 |
Document ID | / |
Family ID | 50185692 |
Filed Date | 2014-03-06 |
United States Patent
Application |
20140060508 |
Kind Code |
A1 |
Floyd; Mandel ; et
al. |
March 6, 2014 |
Thermal Management of a Propulsion Circuit in an Electromagnetic
Munition Launcher
Abstract
Apparatus and methods provide thermal management of a propulsion
circuit in an electromagnetic munition launcher.
Inventors: |
Floyd; Mandel; (Alexandria,
VA) ; Smith; David Lewis; (Albuquerque, NM) ;
Kaye; Ronald J.; (Albuquerque, NM) ; Aubuchon;
Matthew; (Escondido, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Floyd; Mandel
Smith; David Lewis
Kaye; Ronald J.
Aubuchon; Matthew |
Alexandria
Albuquerque
Albuquerque
Escondido |
VA
NM
NM
CA |
US
US
US
US |
|
|
Assignee: |
LOCKHEED MARTIN CORPORATION
Bethesda
MD
SANDIA CORPORATION
Albuquerque
NM
|
Family ID: |
50185692 |
Appl. No.: |
13/279792 |
Filed: |
October 24, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61523664 |
Aug 15, 2011 |
|
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Current U.S.
Class: |
124/3 |
Current CPC
Class: |
F41B 6/003 20130101 |
Class at
Publication: |
124/3 |
International
Class: |
F41B 6/00 20060101
F41B006/00 |
Claims
1. A propulsion circuit in an electromagnetic munition launcher
that is capable of launching a munition, the propulsion circuit
comprising: a first coil that is dimensioned and arranged to
inductively couple to a second coil in an armature circuit that is
associated with the munition; a high-energy capacitor; a diode
having an anode that is dimensioned and arranged to electrically
couple to the high-energy capacitor and having a cathode that is
dimensioned and arranged to electrically couple to a first terminal
of the first coil; and a plurality of switches for actuating a
plurality of states of the propulsion circuit, the plurality of
states comprising: a drive state that is actuated when a first
switch is in a closed position and a second switch is in the closed
position, wherein the high-energy capacitor discharges and a first
flow of electric current through the first coil inductively couples
the first coil to the second coil; a recovery state that follows
the drive state, and that is actuated when a third switch is in the
closed position while the first and second switches are in an open
position, thereby recharging the high-energy capacitor at least in
part; and a charging state that is actuated when a fourth switch is
in the closed position while the first, second, and third switches
are in the open position and no current flows through the first
coil, thereby charging the high-energy capacitor from a power
source; wherein the recovery state that follows the drive state
limits a rise in the temperature of the first coil as compared to
the rise in the absence of the recovery state, wherein the rise
results from a residual energy arising from the drive state.
2. The propulsion circuit of claim 1 wherein the plurality of
states further comprises: a safe state that is actuated when a
fifth switch is in the closed position while the first, second,
third, and fourth switches are in the open position and no current
flows through the first coil, thereby discharging the high-energy
capacitor via a second flow of electric current through a first
load component.
3. The propulsion circuit of claim 2 wherein, when the third switch
remains in the closed position while the safe state is actuated,
the safe state operates in conjunction with the recovery state.
4. The propulsion circuit of claim 1 wherein the recovery state
that follows the drive state enables the electromagnetic munition
launcher to launch again sooner in a next drive state as compared
to launching again in the absence of the intervening recovery
state.
5. The propulsion circuit of claim 1 wherein, in the drive state,
the first switch is electrically coupled to a first terminal of the
first coil and to a first terminal of the high-energy capacitor,
and wherein the second switch is electrically coupled to a second
terminal of the first coil and to a second terminal of the
high-energy capacitor.
6. The propulsion circuit of claim 1 wherein, in the recovery
state, the third switch is electrically coupled to a second
terminal of the first coil and to a first terminal of the
high-energy capacitor, and wherein a first diode is electrically
coupled to a first terminal of the first coil and to a second
terminal of the high-energy capacitor.
7. The propulsion circuit of claim 1 wherein the propulsion circuit
is one of a plurality of propulsion circuits in the electromagnetic
munition launcher, each propulsion circuit being capable of
operating in the drive state followed by the recovery state;
wherein a plurality of coils corresponding to the plurality of
propulsion circuits are arranged in succession along a launch tube
of the electromagnetic munition launcher; and wherein the drive
state of each propulsion circuit provides, via the corresponding
successive coil, an acceleration to the munition being
launched.
8. The propulsion circuit of claim 1 wherein the munition is one of
a missile, a countermeasure, an unmanned aerial vehicle (UAV), a
projectile, and a launch package.
9. The propulsion circuit of claim 1 wherein the recovery state is
also actuated when a voltage across the first coil drops below zero
Volts.
10. An electromagnetic munition launcher comprising: a launch tube
that accommodates a munition to be launched; and a propulsion
circuit that comprises a first coil, a high-energy capacitor, and a
plurality of switches for actuating a plurality of states of the
propulsion circuit, the plurality of states comprising: a drive
state that is actuated when a first switch is in a closed position
and a second switch is in the closed position, wherein the
high-energy capacitor discharges and a first flow of current
through the first coil inductively couples the first coil to a
second coil in an armature circuit that is associated with the
munition; a recovery state that follows the drive state, and that
is actuated when a third switch is in the closed position while the
first and second switches are in an open position, thereby
recharging the high-energy capacitor at least in part; and a
charging state that is actuated when a fourth switch is in the
closed position while the first, second, and third switches are in
the open position and no current flows through the first coil,
thereby charging the high-energy capacitor from a power source;
wherein the recovery state that follows the drive state limits a
rise in the temperature of the first coil as compared to the rise
in the absence of the recovery state, wherein the rise results from
a residual energy arising from the drive state.
11. The electromagnetic munition launcher of claim 10 wherein the
plurality of states further comprises: a safe state that is
actuated when a fifth switch is in the closed position while the
first, second, third, and fourth switches are in the open position
and no current flows through the first coil, thereby discharging
the high-energy capacitor via a second flow of electric current
through a first load component.
12. The electromagnetic munition launcher of claim 10 wherein the
recovery state that follows the drive state and operates before the
charging state enables the propulsion circuit to reach the charging
state sooner as compared to reaching the charging state in the
absence of the intervening recovery state.
13. The electromagnetic munition launcher of claim 10 wherein the
recovery state enables some residual energy to be recovered for
charging the high-energy capacitor during the recovery state.
14. The electromagnetic munition launcher of claim 10 further
comprising: a plurality of propulsion circuits, each propulsion
circuit being capable of operating in the drive state followed by
the recovery state; wherein a plurality of coils corresponding to
the plurality of propulsion circuits are arranged in succession
along the launch tube; and wherein the drive state of each
propulsion circuit provides, via the corresponding successive coil,
an acceleration to the munition being launched.
15. The electromagnetic munition launcher of claim 14 wherein the
recovery state that follows the drive state of each propulsion
circuit enables the electromagnetic munition launcher to launch
again sooner in a next drive state of the respective propulsion
circuit as compared to launching again in the absence of the
recovery state, the recovery state thereby increasing a launching
capacity of the electromagnetic munition launcher.
16. A method for thermal management of a propulsion circuit of an
electromagnetic munition launcher, the method comprising: actuating
a charging state in the propulsion circuit, wherein the charging
state comprises charging a high-energy capacitor from a power
source, and wherein the propulsion circuit comprises the
high-energy capacitor and a first coil; actuating a drive state in
the propulsion circuit, wherein the drive state comprises
discharging the high-energy capacitor at least in part, and further
comprises a flow of electric current that flows through the first
coil causing it to inductively couple to a second coil in an
armature circuit; and following the drive state, actuating a
recovery state in the propulsion circuit, wherein the recovery
state comprises charging the high-energy capacitor at least in
part, and wherein the recovery state limits a rise in the
temperature of the first coil as compared to the rise in the
absence of the recovery state, and wherein the rise results from a
residual energy arising from the drive state.
17. The method of claim 16 further comprising: actuating a safe
state in the propulsion circuit, wherein the safe state discharges
the high-energy capacitor via a load, and wherein no electric
current flows through the propulsion coil during the safe
state.
18. The method of claim 16 further comprising: actuating a next
charging state in the propulsion circuit; wherein the recovery
state that follows the drive state and operates before the next
charging state enables the propulsion circuit to reach the next
charging state sooner as compared to actuating the next charging
state absent the intervening recovery state.
19. The method of claim 16 further wherein: the actuating of the
drive state comprises closing a first switch and a second switch in
the propulsion circuit, and wherein the first switch is
electrically coupled to a first terminal of the first coil and to a
first terminal of the high-energy capacitor, and wherein the second
switch is electrically coupled to a second terminal of the first
coil and to a second terminal of the high-energy capacitor; the
actuating of the recovery state comprises opening the first switch
and the second switch and closing a third switch in the propulsion
circuit, and wherein the third switch is electrically coupled to a
second terminal of the first coil and to a first terminal of the
high-energy capacitor, and wherein a first diode is electrically
coupled to a first terminal of the first coil and to a second
terminal of the high-energy capacitor; and the thermal management
of the propulsion circuit is enabled by actuating the recovery
state immediately following the drive state.
20. The method of claim 16 further comprising: successively
actuating the recovery state following the drive state for each of
a plurality of propulsion circuits in the electromagnetic munition
launcher, wherein a plurality of coils corresponding to the
plurality of propulsion circuits are arranged in succession along a
launch tube, and wherein the drive state of each propulsion circuit
provides, via each successive corresponding coil, an acceleration
to a munition being launched by the electromagnetic munition
launcher.
Description
STATEMENT OF RELATED CASES
[0001] This case claims priority to U.S. Provisional Application
Ser. No. 61/523,664, filed on 15 Aug. 2011 (attorney docket no.
711-293us), and which is incorporated by reference herein.
FIELD OF THE INVENTION
[0002] The present invention relates to electromagnetic munition
launchers in general, and, more particularly, to thermal management
thereof.
BACKGROUND OF THE INVENTION
[0003] An electromagnetic launcher based on induction coilgun
technology comprises coil electromagnets. The coils are
sequentially arranged along a launch tube to accelerate a
projectile to a desired velocity for launch. The coils are powered
on and off in sequence to accelerate the projectile and expel it
out of the launch tube. The sequentially-arranged coils and their
accompanying circuits are commonly known as the "stages" of the
coilgun. See FIG. 1.
[0004] The coilgun acts as a linear induction motor with respect to
the projectile. The projectile is associated with an armature
circuit that is part of, or coupled with, or supports the
projectile. When powered, the propulsion coil inductively couples
to an armature coil in the armature circuit as it passes the
propulsion coil. A coilgun provides no physical contact between the
projectile and the propulsion coil. The acceleration is achieved
through induction and magnetic forces. In contrast, a railgun uses
sliding contacts or rails to transmit energy to the projectile.
[0005] Coilguns are often designed by and for hobbyists for
low-power applications that shoot light payloads. However, larger
systems have been disclosed for defense applications. For example,
U.S. Pat. No. 7,549,365 B2 discloses an electromagnetic missile
launcher ("EMML") with a catapult-sled that supports a missile as
it is being launched. The catapult-sled is electromagnetically
accelerated by induction as between armature coils on the
catapult-sled and successively arranged propulsion coils along the
launch tube. The EMML launcher has multiple cells, each cell being
equipped with the coilgun and catapult-sled. The armature is part
of the sled that guides, but does not launch with, the projectile.
U.S. Pat. No. 7,549,365 B2 is hereby incorporated by reference
herein. If there are any contradictions or inconsistencies between
the present case and one or more of the cases that are incorporated
by reference herein, the claims in the present case are to be
interpreted consistent with the language herein.
[0006] Another catapult-style electromagnetic launcher is the
"Electro Magnetic Countermeasure Launcher" ("EMCL") in U.S. Pat.
No. 7,895,931, which is incorporated by reference herein. The
illustrative EMCL has a coilgun-based design that uses an
electromagnetic catapult to throw a countermeasure device with
controlled force and direction, while minimizing the launch
signature. The EMCL comprises a launch tube that propels a series
of countermeasure payloads. The EMCL typically requires repetitive
firings from the same set of propulsion coils in relatively rapid
succession (i.e., burst), because the same launch tube is used to
launch the series of countermeasure payloads. The equipped
armatures are ejected with or as a part of the countermeasure
payload. Additional payloads are loaded and then fired from the
same launch tube.
[0007] One drawback of coilgun-based designs arises from the
residual energy that is left over in the propulsion coil(s) and
associated propulsion circuitry after firing. The residual energy
dissipates as heat in the propulsion coil. See FIG. 2B. The coilgun
operator must then wait for the coil to cool down before the
coilgun is ready to fire/launch again. Additionally, the excess
heat tends to lower the longevity of the coil. In a weapons-grade
coilgun, the propulsion coil is an expensive component, and
replacing the coil takes a substantial toll on the weapon's
maintainability. Moreover, the excess heat makes the weapon
vulnerable to infrared detection. FIGS. 1, 2A, and 2B illustrate
some of the abovementioned principles of the prior art.
[0008] FIG. 1 depicts the salient elements of a typical induction
coilgun system in the prior art, including coilgun 100 and
projectile 107. Coilgun 100 comprises: propulsion circuits 101-1,
101-2, and 101-3; and launch tube 105; each propulsion circuit
101-j comprises propulsion coil 103-j and power supply 111-j, where
j=1, 2, 3. Coilgun 100 is illustrated with three stages, 1, 2, and
3, each stage comprising only one propulsion circuit 101-j, but it
will be clear to those having ordinary skill in the art that any
number of stages and any number of component propulsion circuits
per stage are possible.
[0009] Propulsion coil 103-j is well known in the art; when
electrical current flows through it, the propulsion coil is capable
of inductively coupling to an armature coil that falls within its
inductive influence as it travels through the launch tube.
[0010] Launch tube 105 is well known in the art and encloses,
supports, and/or guides accelerating projectile 107.
[0011] Projectile 107 is accelerated by the launcher to travel in
the direction of the arrow as shown. The illustrative projectile
107 comprises armature circuit 109 that, through inductive coupling
to the successively arranged propulsion coils 103-j in the
corresponding propulsion circuits 101-j, enables projectile 107 to
accelerate out of launch tube 105.
[0012] Power supply 111-j is well known in the art and acts as a
power source to propulsion circuit 101-j.
[0013] Control sub-systems are not shown in the present figure or
in FIGS. 2A and 2B. Electronics (accompanied by hardware and/or
software) may be used as the control sub-system in some embodiments
of coilgun 100 to operate the coilgun. In some embodiments, the
control sub-system is manual.
[0014] FIG. 2A depicts the salient elements of prior art propulsion
circuit 101-j while in the firing state; also shown is armature
circuit 109, which is associated with projectile 107 (not shown),
and which comprises armature coil 209. Propulsion circuit 101-j
comprises the following salient electrical components: propulsion
coil 103-j; capacitor 201; switch 203; and diode 205. Each of these
electrical components is well-known in the art. During the firing
state, switch 203 is in a closed position and electrical current
207 flows through a loop that comprises capacitor 201, switch 203,
and propulsion coil 103-j. In the firing state, propulsion coil
103-j inductively couples to armature coil 209 as projectile 107
(not shown) accelerates through launch tube 105 (not shown).
[0015] FIG. 2B depicts the salient elements of prior art propulsion
circuit 101-j while in the post-firing state. The post-firing state
follows the firing state of FIG. 2A. Propulsion circuit 101-j
comprises the same salient electrical components as shown in FIG.
2A. During the post-firing state, switch 203 is in an open position
and electrical current 211 flows through a loop that comprises
diode 205 and propulsion coil 103-j.
[0016] In the post-firing state, propulsion coil 103-j experiences
a rise in temperature that arises from residual energy left over
from the firing state. As electrical current 211 flows, it heats
propulsion coil 103-j through resistive dissipation of the coil
windings, manifesting as heat 213. As noted, the temperature rise
and the heat dissipation are significant drawbacks.
SUMMARY OF THE INVENTION
[0017] The inventors of the present invention recognized that in
regard to weapons applications of induction coilgun technology, the
high levels of energy involved in munitions launches generate an
amount of heat and a correspondingly long cooling period that
substantially delays how soon the launcher can be ready for the
next launch. This delay is not compatible with the rapid-fire needs
of munitions launchers that must repetitively launch a sufficient
number of munitions in a short time to satisfy mission objectives.
The present inventors recognized that the amount of excess heat and
the resultant cooling delay can make the difference between a
viable weapon and a nonviable one--at least with regard to
supporting repetitive fire. An electromagnetic munition launcher
according to the present invention incorporates thermal management
of the propulsion coils to ameliorate these drawbacks.
[0018] The munition is distinct from and not a part of the
disclosed launcher. The term "munition" as used in the present
disclosure is defined as any item that can be launched from the
electromagnetic munition launcher, and can refer to a missile, a
countermeasure, an unmanned aerial vehicle (UAV), a projectile, a
launch package, etc.; a munition may, but need not, contain a
warhead.
[0019] The illustrative electromagnetic munition launcher according
to the present invention is based on induction coilgun technology
that comprises an enhanced propulsion circuit capable of recovering
energy after the launcher fires. The energy recovery feature limits
how much the temperature rises in the propulsion coil and its
associated circuitry after executing a launch. As noted, launching
produces residual energy that is left over in the propulsion
circuit. Without thermal management, the residual energy ordinarily
would dissipate as heat in the propulsion coils. Thus, limiting the
rise in temperature reduces the cooling delay and increases the
weapon's firing (or repetition) rate; it also reduces the
launcher's infrared footprint, and extends the longevity of the
propulsion coil. A further benefit is that the prime power source
has reduced power demands for charging the launcher prior to the
next firing, and therefore can be smaller/lighter/less costly. In
the aggregate, having lower weight, volume, and costs are desirable
objectives that are advantageously captured in the disclosed
electromagnetic munition launcher.
[0020] In contrast to an ordinary electromagnetic munition launcher
that lacks the disclosed enhancements, the present electromagnetic
munition launcher substantially limits the rise in temperature in
the launcher's propulsion coils. This is accomplished by recovering
the residual energy after every launch. The recovered energy
recharges a high-energy capacitor in the enhanced propulsion
circuit. The capacitor then discharges in the next launch.
According to the present invention, the enhanced propulsion circuit
is designed to operate in a plurality of states, defined herein as
a drive state, a recovery state, a charging state, and a safe
state. See FIG. 10.
[0021] The "drive state" enables the launcher to launch a munition.
Typically, the launcher has a plurality of propulsion circuits that
are sequentially arranged in stages. The propulsion circuits are
energized sequentially to accelerate the munition to its proper
launch speed. Thus, to achieve the improved firing/launching rate
of the launcher, every propulsion circuit in the launcher is
enhanced according to the present invention.
[0022] The "recovery state" follows the drive state. The recovery
state provides the thermal management of the propulsion coils. The
enhanced propulsion circuit comprises a high-energy capacitor (or,
in some embodiments, a capacitor block) that discharges during the
drive state and must be recharged before the next launch can occur.
According to the present invention, the high-energy capacitor is
recharged, at least in part, in the course of the recovery state.
Channeling at least some of the residual energy into recharging the
high-energy capacitor keeps the energy from dissipating as excess
heat. With the recovery state, the inventors experimentally
demonstrated that as little as 15 percent of the residual energy
can be converted to heat, while the rest is applied to recharging
the high-energy capacitor. In contrast, without energy recovery, as
much as 70 percent of the residual energy converts to heat.
[0023] Consequently, the recovery state has the effect of
substantially limiting the rise in temperature of the propulsion
coil and its associated propulsion circuit as compared to the rise
in temperature in the absence of the recovery state, i.e., as
compared to prior art designs. Therefore, with far less heat to
dissipate and a shorter cooling time, the recovery state enables
the electromagnetic munition launcher to launch again sooner in a
next drive state as compared to launching again in the absence of
the recovery state, i.e., as compared to prior art designs.
Furthermore, using energy recovery to help charge the high-energy
capacitor substantially reduces the performance demands placed upon
the primary power source of the launcher. This can translate into a
smaller power source that can have lower weight, lower volume,
and/or lower costs--all advantageous to the present invention.
[0024] It should be noted that the thermal management provided by
the recovery state need not be exclusive to the launcher, because
in some embodiments, additional thermal management techniques
supplement the recovery state, for example, but not limited to,
forced air cooling, liquid cooling, improved materials, improved
components, etc., depending upon the operational requirements of
the launcher (e.g., the firing rate). Thus, in some embodiments,
the thermal management provided by the recovery state has the
capacity to reduce or eliminate supplemental techniques that would
be otherwise employed, resulting in the advantageous effects
recited above--namely lower weight, lower volume, and/or lower
costs associated with deploying and maintaining the launcher.
[0025] The "charging state" charges the high-energy capacitor from
a prime power source to prepare the propulsion circuit for the next
launch. A charging state that follows the recovery state delivers
less charge to the high-energy capacitor, because the recovery
state partially recharged it. Consequently, the charging state
takes less time when it follows the recovery state as compared to
charging after launching, i.e., as compared to prior art designs.
Moreover, the launcher is more energy-efficient. The inventors
experimentally demonstrated that as much as 20 percent of the power
needed to fully charge the high-energy capacitor was recovered
through the recovery state.
[0026] The "safe state" provides a way to discharge energy present
in the propulsion circuit via a load component(s). The safe state
is triggered in case of a misfire or for another purpose that
requires a safe discharge of energy away from the propulsion coil.
The safe state discharges the high-energy capacitor via the load
component. In contrast to the recovery state, the safe state relies
on heat dissipation in the load component(s) to discharge excess
energy. In some embodiments the safe state operates in conjunction
with the recovery state.
[0027] The enhanced propulsion circuit according to the present
invention comprises a plurality of switches. The switches are
arranged and electrically coupled such that, depending on the open
and closed positions of the respective switches, they actuate one
of the disclosed states. By rapidly changing the configuration of
the switches at the right time, i.e., actuating the recovery state
following a launch (drive state), the significant residual
propulsion coil energy is captured and stored for the next launch.
Minimizing the energy loss has a major impact on operational
efficiency, reduced heating of the propulsion coils, coil
lifetimes, launcher repetition rate, and the total number of
launcher shots per burst.
[0028] An apparatus according to the present invention is a
propulsion circuit in an electromagnetic munition launcher that is
capable of launching a munition, the propulsion circuit comprising:
a first coil that is dimensioned and arranged to inductively couple
to a second coil in an armature circuit that is associated with the
munition; a high-energy capacitor; a diode having an anode that is
dimensioned and arranged to electrically couple to the high-energy
capacitor and having a cathode that is dimensioned and arranged to
electrically couple to a first terminal of the first coil; and a
plurality of switches for actuating a plurality of states of the
propulsion circuit, the plurality of states comprising: a drive
state that is actuated when a first switch is in a closed position
and a second switch is in the closed position, wherein the
high-energy capacitor discharges and a first flow of electric
current through the first coil inductively couples the first coil
to the second coil; a recovery state that follows the drive state,
and that is actuated when a third switch is in the closed position
while the first and second switches are in an open position,
thereby recharging the high-energy capacitor at least in part; and
a charging state that is actuated when a fourth switch is in the
closed position while the first, second, and third switches are in
the open position and no current flows through the first coil,
thereby charging the high-energy capacitor from a power source;
wherein the recovery state that follows the drive state limits a
rise in the temperature of the first coil as compared to the rise
in the absence of the recovery state, wherein the rise results from
a residual energy arising from the drive state.
[0029] A method for thermal management of a propulsion circuit of
an electromagnetic munition launcher, according to the present
invention, comprises: actuating a charging state in the propulsion
circuit, wherein the charging state comprises charging a
high-energy capacitor from a power source, and wherein the
propulsion circuit comprises the high-energy capacitor and a first
coil; actuating a drive state in the propulsion circuit, wherein
the drive state comprises discharging the high-energy capacitor at
least in part, and further comprises a flow of electric current
that flows through the first coil causing it to inductively couple
to a second coil in an armature circuit; and following the drive
state, actuating a recovery state in the propulsion circuit,
wherein the recovery state comprises charging the high-energy
capacitor at least in part, and wherein the recovery state limits a
rise in the temperature of the first coil as compared to the rise
in the absence of the recovery state, and wherein the rise results
from a residual energy arising from the drive state.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] FIG. 1 depicts the salient elements of a typical induction
coilgun in the prior art.
[0031] FIG. 2A depicts the salient elements of a propulsion circuit
in the firing state, according to the prior art.
[0032] FIG. 2B depicts the salient elements of a propulsion circuit
while in the post-firing state, according to the prior art.
[0033] FIG. 3 depicts the salient elements of electromagnetic
munition launcher 300 according to a first embodiment of the
present invention.
[0034] FIG. 4 depicts the salient elements of electromagnetic
munition launcher 400 according to a second embodiment of the
present invention.
[0035] FIG. 5 depicts a circuit diagram of the salient elements of
enhanced propulsion circuit 301-j operating in the charging
state.
[0036] FIG. 6A depicts a circuit diagram of the salient elements of
enhanced propulsion circuit 301-j operating in a first phase of the
drive state.
[0037] FIG. 6B depicts a circuit diagram of the salient elements of
enhanced propulsion circuit 301-j operating in a second phase of
the drive state.
[0038] FIG. 7 depicts a circuit diagram of the salient elements of
enhanced propulsion circuit 301-j operating in the recovery
state.
[0039] FIG. 8 depicts a circuit diagram of the salient elements of
enhanced propulsion circuit 301-j operating in the safe state.
[0040] FIG. 9 depicts the salient operations of method 900
according to an embodiment of the present invention.
[0041] FIG. 10 depicts the salient operational states of enhanced
propulsion circuit 301-j.
DETAILED DESCRIPTION
[0042] Some structures and devices that are well-known in the art
are depicted in block diagram form in the figures herein, to keep
salient aspects of the present invention from being unnecessarily
obscured.
[0043] In addition to the terms defined earlier, the following
terms are defined for use in this disclosure and in the
accompanying claims: [0044] The term "electrically connected" means
that two objects are in direct electrical contact without any
intervening elements. In other words, the region of contact between
the two objects remains at a substantially uniform voltage for
substantially any current (neglecting any voltage drop due to the
resistivity of the physical connection medium, such as a wire).
[0045] The term "electrically coupled" means that two objects are
in electrical contact. This can be via direct physical contact
(e.g., a plug in an electrical outlet, etc.), via an
electrically-conductive intermediate (e.g., a wire that connects
devices, etc.), or via intermediate devices, etc. (e.g., a resistor
electrically connected between two other electrical devices, etc.).
The term does not refer to induction. [0046] The terms "closed
position" and "open position" in reference to switch components
refer to whether a switch component is conducting electrical
current or not conducting, respectively. These terms thus refer to
circuit logic and do not necessarily describe a physical position
of the switch.
[0047] FIG. 3 depicts the salient elements of electromagnetic
munition launcher 300 according to a first embodiment of the
present invention; munition 307 is also shown. Electromagnetic
munition launcher 300 comprises: enhanced propulsion circuits
301-j, where j=1, 2, 3; launch tube 305; and control electronics
311. Each propulsion circuit 301-j comprises propulsion coil 303-j,
where j=1, 2, 3. Enhanced propulsion circuit 301-j is described in
more detail in respect to FIGS. 5 through 8.
[0048] Electromagnetic munition launcher 300 is illustrated with
three stages--1, 2, and 3--each stage comprising only one enhanced
propulsion circuit 301-j, but it will be clear to those having
ordinary skill in the art, after reading the present disclosure,
how to make and use electromagnetic munition launcher 300 with any
number of stages; or with any number of enhanced propulsion
circuits 301-j per stage; or with any combination thereof.
[0049] Enhanced propulsion circuit 301-j comprises propulsion coil
303-j and is discussed in more detail in regard to the subsequent
figures. Enhanced propulsion circuit 301-j performs the principal
functions of the present invention. It should be noted that the
figures herein depict the propulsion coils as being physically
co-located with the enhanced propulsion circuits, but this is
merely illustrative for simplicity and to help enhance
understanding of the present invention. Only an electrical coupling
as between the propulsion coil(s) and the rest of the enhanced
propulsion circuit comprising it (them) is required for proper
operation of the illustrative embodiment. In practice, the
propulsion coil(s) is physically distant from the rest of the
enhanced propulsion circuit in order to accommodate requirements of
space, physical arrangement, weight, and cooling that are relevant
to the respective embodiment of the present invention.
[0050] Launch tube 305 is well known in the art and encloses,
supports, and/or guides munition 307 as it accelerates out of
launch tube 305.
[0051] Munition 307 is accelerated by the launcher to travel in the
direction of the arrow as shown. In the illustrative embodiment,
munition 307 is a missile. As defined above, munition 307 can be
any of a missile, a countermeasure, an unmanned aerial vehicle
(UAV), and further, munition 307 may, but need not, contain a
warhead. In some embodiments, munition 307 is the same as
projectile 107. Munition 307 is not part of electromagnetic
munition launcher 300. Munition 307 comprises armature circuit
309.
[0052] Armature circuit 309, through inductive coupling of its
armature coil to the successively arranged propulsion coils 303-j
in enhanced propulsion circuits 301-j, enables munition 307 to
accelerate out of launch tube 305.
[0053] Control electronics 311 comprises the control sub-system of
electromagnetic munition launcher 300. Control electronics 311
comprises hardware and/or software (executing on a data processor)
and connective components that control the operation of enhanced
propulsion circuits 301-j. In the illustrative embodiment, control
electronics 311 controls the operation of electromagnetic munition
launcher 300 and comprises the weapons control system that provides
targeting and flight information and firing authority to launch
munition 307. In some embodiments, control electronics 311
comprises an interface to a separate weapons control system and
transmits appropriate commands to the propulsion circuitry and to
other components of the launcher. How the weapons control system
interfaces with and is physically arranged in respect to control
electronics 311 is not relevant to the salient elements of the
present invention.
[0054] Control electronics 311 actuates power and/or switches that
are in enhanced propulsion circuit 301-j to activate the launcher
and to enable at least some of the operational states that are
described in more detail below. Control electronics 311 is capable
of sending control signals to enhanced propulsion circuit 301-j;
control electronics 311 is further capable of monitoring the
operation of the individual enhanced propulsion circuits, of the
launcher in general, and of the munition and associated armature to
the extent necessary to perform its control functions. The relevant
interactions between control electronics 311 and respective
components of enhanced propulsion circuit 301-j are described in
more detail in subsequent figures. A person having ordinary skill
in the art will recognize, after reading the present disclosure,
how to make design trade-offs between control electronics 311 and
components of enhanced propulsion circuit 301-j to satisfy cost and
performance requirements of electromagnetic munition launcher 300.
Some embodiments of the present invention comprise more than one
control electronics 311.
[0055] It will be clear to those having ordinary skill in the art,
after reading the present disclosure, how to make and use
electromagnetic munition launcher 300. The direction of launch
shown herein is illustrative, and it will be clear to those having
ordinary skill in the art, after reading the present disclosure,
how to make and use electromagnetic munition launcher 300 such that
it launches munition 307 in any direction.
[0056] FIG. 4 depicts the salient elements of electromagnetic
munition launcher 400 according to a second embodiment of the
present invention; munition 407 is also shown. Electromagnetic
munition launcher 400 comprises: enhanced propulsion circuits
401-j, where j=1 . . . n; launch tube 405; control electronics 411;
and sled 413, which comprises armature circuits 409-k, where k=1 .
. . m.
[0057] Electromagnetic munition launcher 400 is illustrated with
three stages, 1, 2, and 3, each stage comprising a plurality of
enhanced propulsion circuits 401-j. It will be clear to those
having ordinary skill in the art, after reading the present
disclosure, how to make and use electromagnetic munition launcher
400 with any number of stages; or with any number of enhanced
propulsion circuits 401-j per stage; or with any combination
thereof.
[0058] Enhanced propulsion circuit 401-j is the same as enhanced
propulsion circuit 301-j. In some embodiments, enhanced propulsion
circuit 401-j is adapted to the particular architecture of
electromagnetic munition launcher 400. It should be noted that the
figures herein depict the propulsion coils as being physically
co-located with the enhanced propulsion circuits, but this is
merely illustrative for simplicity and to help enhance
understanding of the present invention. Only an electrical coupling
as between the propulsion coil(s) and the rest of the enhanced
propulsion circuit comprising it (them) is required for proper
operation of the illustrative embodiment. In practice, the
propulsion coil(s) is physically distant from the rest of the
enhanced propulsion circuit in order to accommodate requirements of
space, physical arrangement, weight, and cooling that are relevant
to the respective embodiment of the present invention.
[0059] Launch tube 405 is well known in the art. In some
embodiments, launch tube 405 is the same as launch tube 305; in
some alternative embodiments, launch tube 405 comprises other
components and functionalities necessary for the operation of sled
413 and the particular architecture of electromagnetic munition
launcher 400.
[0060] Armature circuit 409-k is part of sled 413. In some
embodiments, armature circuit 409-k operates the same as armature
circuit 309. It will be clear to those having ordinary skill in the
art, after reading the present disclosure, how to make alternative
embodiments that are consistent with electromagnetic munition
launcher 400.
[0061] Control electronics 411 comprises the control sub-system of
electromagnetic munition launcher 400. In the illustrative
embodiment, control electronics 411 is the same as control
electronics 311, and is further adapted to the particular
architecture of electromagnetic munition launcher 400. Like control
electronics 311, control electronics 411 actuates power and/or
switches that are in enhanced propulsion circuit 401-j to enable at
least some of the operational states of propulsion circuit 401-j as
described in more detail below (in regard to enhanced propulsion
circuit 301-j). Control electronics 411 also controls the operation
of sled 413. A person having ordinary skill in the art will
recognize, after reading the present disclosure, how to make design
trade-offs among functionalities of control electronics 411 and
corresponding components of enhanced propulsion circuits 401-j and
armature circuits 409-k to satisfy cost and performance
requirements of electromagnetic munition launcher 400. Some
embodiments of the present invention comprise more than one control
electronics 411.
[0062] Sled 413 is part of electromagnetic munition launcher 400
and comprises at least one armature circuit 409-k that, through
inductive coupling to the successively arranged enhanced propulsion
circuits 401-j, enables munition 407 to accelerate out of launch
tube 405. Thus, according to this second illustrative embodiment,
electromagnetic munition launcher 400 comprises the operative
armature circuits and armature coils required for the launch of
munition 407.
[0063] Munition 407 is accelerated to travel in the direction of
the arrow as shown. In the illustrative embodiment, munition 407 is
a missile. As defined above, munition 407 can be any of a missile,
a countermeasure, an unmanned aerial vehicle (UAV), and further,
munition 407 may, but need not, contain a warhead. Munition 407 is
not part of electromagnetic munition launcher 400.
[0064] It will be clear to those having ordinary skill in the art,
after reading the present disclosure, how to make and use
electromagnetic munition launcher 400. The direction of launch
shown herein is illustrative, and it will be clear to those having
ordinary skill in the art, after reading the present disclosure,
how to make and use electromagnetic munition launcher 400 such that
it launches munition 407 in any direction.
[0065] FIG. 5 depicts a circuit diagram of the salient elements of
enhanced propulsion circuit 301-j operating in the charging state
according to an embodiment of the present invention. In general,
enhanced propulsion circuit 301-j comprises the following
electrical components: load 501; switch 502; power source 503; load
504; switch 505; high-energy capacitor 506; switch 507; diode 508;
switch 509; switch 511; and propulsion coil 303-j. Enhanced
propulsion circuit 301-j functions at least in part under the
control of control electronics 311 (not shown), to perform some of
the salient operations of electromagnetic munition launcher 300
according to the present invention.
[0066] As noted in the Summary, enhanced propulsion circuit 301-j
according to the illustrative embodiment is designed to operate in
a plurality of states: a charging state, a drive state, a recovery
state, and a safe state. However, it is to be understood that some
alternative embodiments do not operate in all these states and
therefore do not require the corresponding components that are
illustrated herein. During ordinary operation, enhanced propulsion
circuit 301-j executes the sequence of charging state, drive state,
and recovery state, cycling back to a next sequence of charging
state, drive state, and recovery state.
[0067] In the charging state, the enumerated components are
electrically coupled as illustrated in the present figure. The
charging state charges high-energy capacitor 506 from power source
503 to prepare enhanced propulsion circuit 301-j for the next
launch, i.e., for the drive state. During the charging state,
switch 502 is in a closed position and switches 505, 507, 509, and
511 are in an open position; electrical current 513 flows clockwise
through a loop that comprises high-energy capacitor 506, power
source 503, switch 502, and load 501.
[0068] Load 501 is well known in the art. In the illustrative
embodiment, load 501 is a resistor, and it will be clear to those
having ordinary skill in the art how to make and use load 501 with
other components of like functionality.
[0069] Switch 502 is well known in the art. Switch 502 actuates the
charging state when it is closed--under control of control
electronics 311--and the other switches are open. It will be clear
to those having ordinary skill in the art how to implement switch
502 with other types of switches or other components of like
functionality.
[0070] Power source 503 is a power source that is well known in the
art. Power source 503 provides the power that charges high-energy
capacitor 506 during the charging state. It will be clear to those
having ordinary skill in the art how to make and use power source
503.
[0071] High-energy capacitor 506 is a capacitor that sustains high
voltage and a high discharge rate. High-energy capacitor 506 is
suitable for use with enhanced propulsion circuit 301-j, because it
acts as a pulse power source capable of relatively-rapid charge and
discharge. In the illustrative embodiment, high-energy capacitor
506 sustains high voltage for up to 60 seconds, and it will be
clear to those having ordinary skill in the art, after reading the
present disclosure, how to select and use other suitable
high-energy capacitors. In some embodiments, high-energy capacitor
506 is a block comprising a plurality of high-energy
capacitors.
[0072] It will be clear to those having ordinary skill in the art,
after reading the present disclosure, how to make and use enhanced
propulsion circuit 301-j in the charging state. The remaining
components illustrated in FIG. 5 are described in more detail in
the figures below.
[0073] FIGS. 6A and 6B depict circuit diagrams of the salient
elements of enhanced propulsion circuit 301-j operating in the
drive state according to an embodiment of the present invention;
also shown is armature circuit 309, which is associated with
projectile 307 (not shown), and which comprises armature coil 611.
In the drive state, armature circuit 309 falls under the inductive
influence of propulsion coil 303-j as munition 307 travels past
propulsion coil 303-j. At a certain level of granularity the drive
state can be depicted in two phases, as illustrated by FIGS. 6A and
6B. Enhanced propulsion circuit 301-j comprises the electrical
components enumerated in FIG. 5, which are electrically coupled
according to FIGS. 6A and 6B.
[0074] FIG. 6A depicts a circuit diagram of the salient elements of
enhanced propulsion circuit 301-j operating in a first phase of the
drive state. Electrical current 601 flows clockwise through a loop
that comprises high-energy capacitor 506; switch 507 in a closed
position; propulsion coil 303-j; and switch 511 in a closed
position. Switches 502, 505, and 509 are in an open position.
[0075] High-energy capacitor 506 was described above. High-energy
capacitor 506 discharges to provide "pulse" power to propulsion
coil 303-j during the drive state.
[0076] Switch 507 in the illustrative embodiment is a latching-type
semiconductor (thyristor). One or more trigger pulses from control
electronics 311 is driven into the gate terminal of switch 507
until a latching current level is established through the switch
sufficient to latch switch 507 on (in a closed position). In the
illustrative embodiment, the latching current is about 500 mA.
Switch 507 remains latched on until the electrical current through
the switch drops below a holding current level. In the illustrative
embodiment, the holding current level is about 300 mA.
[0077] Switch 511 is not a latching switch like switch 507, and its
conduction path can be closed and opened under the control of a
gate terminal regardless of current level. Switch 511 is triggered
into the closed position by control electronics 311 before
triggering switch 507. It will be clear to those having ordinary
skill in the art, after reading the present disclosure, how to use
a latching-type switch 511 in alternative embodiments of the
present circuit, possibly requiring a corresponding alternative
implementation of control electronics 311.
[0078] It will be clear to those having ordinary skill in the art,
after reading the present disclosure, how to make and use
alternative embodiments of the present invention using alternative
switch technologies, whether latching or non-latching or otherwise,
in conjunction with appropriate support in control electronics 311
or elsewhere in electromagnetic munition launcher 300. Likewise,
some alternative embodiments use a different number and/or a
different arrangement of switches to perform the functions
disclosed in the present figure and in the other figures associated
with the present invention.
[0079] FIG. 6B depicts a circuit diagram of the salient elements of
enhanced propulsion circuit 301-j operating in a second phase of
the drive state. During the drive state, when the LC resonant
circuit of high-energy capacitor 506 and propulsion coil 303-j in
conjunction with armature circuit 309 force the voltage across
propulsion coil 303-j below 0 Volts, switch 507 is forced off (into
an open position) and diode 508 is forced on. The electrical
current through switch 507 falls below the holding current level of
FIG. 6A, thus forcing switch 507 off (open position). The current
flow is picked up by diode 508, as shown, and the voltage across
propulsion coil 303-j is clamped to a low voltage by diode 508.
Resultant electrical current 602 flows clockwise through a loop
comprising diode 508, propulsion coil 303-j, and switch 511 in the
closed position.
[0080] FIG. 7 depicts a circuit diagram of the salient elements of
enhanced propulsion circuit 301-j operating in the recovery state
according to an embodiment of the present invention. Enhanced
propulsion circuit 301-j comprises the electrical components
enumerated in FIG. 5, which are electrically coupled according to
the present figure.
[0081] The recovery state follows the drive state. When armature
circuit 309, which is associated with munition 307 (not shown),
moves sufficiently out of the inductive influence of propulsion
coil 303-j, control electronics 311 opens switch 511 and triggers
switch 509 closed. Electrical current 701 flows counterclockwise
through a loop comprising high-energy capacitor 506, diode 508,
propulsion circuit 303-j, and switch 509 in a closed position.
Switches 502, 505, 507, and 511 are in the open position. The
direction of flow through high-energy capacitor 506 is opposite to
the direction of flow during the drive state of FIG. 6A.
[0082] High-energy capacitor 506 was described above.
[0083] Switch 509 is a non-latching switch. It will be clear to
those having ordinary skill in the art, after reading the present
disclosure, how to use a latching-type switch 509 in alternative
embodiments of the present circuit.
[0084] The current flow in the recovery state has the effect of
charging, at least in part, high-energy capacitor 506. This
provides the thermal management feature of the electromagnetic
munition launcher according to the present invention. As a result
of the above-described drive state, the residual energy that arises
in the drive state manifests as current that flows through
propulsion coil 303-j as shown in FIG. 6B; ordinarily, this would
cause propulsion coil 303-j to heat up substantially--similar to
the prior art circuit of FIG. 2B. However, by actuating the
recovery state according to the present invention, the temperature
rise in propulsion coil 303-j is substantially limited. Thus,
before another launch is attempted, the residual energy is
recovered and channeled into recharging high-energy capacitor 506
during the recovery state. The recovery state typically charges
high-energy capacitor 506 only in part, leaving the full-level
charging to a subsequent charging state that typically follows the
recovery state. The extent of recharge received by high-energy
capacitor 506 during the recovery state relative to the charging
state depends on the implementation of enhanced propulsion circuit
301-j and control electronics 311.
[0085] In a multi-stage launcher, a plurality of propulsion coils
is arranged in succession along the launch tube. Therefore, each
enhanced propulsion circuit that comprises the respective
propulsion coil(s) is capable of operating in the drive state
followed by the recovery state. Therefore, the drive state
manifesting in each successive propulsion coil provides
acceleration to the munition being launched. The recovery state
that follows the drive state of each enhanced propulsion circuit
enables the electromagnetic munition launcher to launch again
sooner in a next drive state of the respective propulsion circuit
as compared to launching again in the absence of the recovery
state, the recovery state thereby increasing a launching capacity
and repetitive rate of the launcher.
[0086] It will be clear to those having ordinary skill in the art,
after reading the present disclosure, how to make and use the
recovery state according to the present invention.
[0087] FIG. 8 depicts a circuit diagram of the salient elements of
enhanced propulsion circuit 301-j operating in the safe state
according to an embodiment of the present invention. Enhanced
propulsion circuit 301-j comprises the electrical components
enumerated in FIG. 5, which are electrically coupled as shown in
the present figure. Electrical current 801 flows counterclockwise
through a loop that comprises high-energy capacitor 506; load 504,
and switch 505 in a closed position. Switches 502, 507, 509, and
511 are in an open position. The safe state is triggered by control
electronics 311 in case of a misfire or for another purpose that
requires a rapid discharge of energy away from propulsion coil
303-j. In contrast to the recovery state, the safe state dissipates
energy as heat. The safe state discharges high-energy capacitor 506
via load component 504.
[0088] Load 504 is well known in the art. In the illustrative
embodiment, load 504 is a resistor, and it will be clear to those
having ordinary skill in the art how to make and use load 504 using
one or more other components of like functionality. Load 504 is
capable of dissipating heat arising from discharging of high-energy
capacitor 506.
[0089] Switch 505 is well known in the art. Switch 505 actuates the
charging state when control of control electronics 311 triggers
switch 505 closed and opens the other switches. It will be clear to
those having ordinary skill in the art how to implement switch 505
using other types of switches or other components of like
functionality.
[0090] High-energy capacitor 506 was described above. The safe
state discharges high-energy capacitor 506.
[0091] It will be clear to those having ordinary skill in the art,
after reading the present disclosure, how to make and use the safe
state according to the present invention. It should be noted that,
by dissipating heat, the safe state provides a thermal management
function that is distinct from the thermal management provided by
the recovery state, because it does not partially recharge the
high-energy capacitor.
[0092] In an alternative embodiment, switch 509 is in a closed
position such that both the safe state and the recovery state are
simultaneously actuated. This combination enables a faster
discharge of the residual energy as compared to using the recovery
state alone, and thus provides for a shorter cooling interval
before the next drive state is possible.
[0093] FIG. 9 depicts the salient operations of method 900
according to an embodiment of the present invention. Method 900
recites the salient operations of the electromagnetic munition
launcher of the present invention, including the operations of the
charging state, the drive state, the recovery state, and the safe
state.
[0094] At operation 901, electromagnetic munition launcher 300/400
actuates a charging state in enhanced propulsion circuit 301-j, via
a trigger from control electronics 311 to close switch 502, wherein
the charging state charges high-energy capacitor 506 from power
source 503; switches 505, 507, 509, and 511 are open in the
charging state.
[0095] At operation 903, electromagnetic munition launcher 300/400
actuates a drive state in enhanced propulsion circuit 301-j, via a
trigger from control electronics 311 to close switch 511.
[0096] At operation 905, switch 507 latches on (closed position) as
a result of a latching current, wherein the drive state discharges
high-energy capacitor 506 and current flows through propulsion coil
303-j; switch 507 remains on (closed) while at or above the holding
current level; switches 502, 505, and 509 are open during the drive
state.
[0097] At operation 907, when voltage in propulsion coil 303-j
drops below 0 Volts and the electrical current through switch 507
drops below the holding current level, switch 507 switches off
(open position).
[0098] At operation 909, electromagnetic munition launcher 300/400
actuates a recovery state in enhanced propulsion circuit 301-j, via
a trigger from control electronics 311 to open switch 511 and close
switch 509, wherein the recovery state reverses the flow of
electric current through high-energy capacitor 506 to charge
high-energy capacitor 506 (at least in part), limiting the rise in
temperature in propulsion coil 303-j; switches 502, 505, 507, and
511 are open during the recovery state.
[0099] At operation 911, electromagnetic munition launcher 300/400
actuates a safe state in enhanced propulsion circuit 301-j, via a
trigger from control electronics 311 to close switch 505, wherein
the safe state discharges high-energy capacitor 506 via load 504,
and no electric current flows through propulsion coil 303-j during
the safe state; switches 502, 507, 509, and 511 are open during the
safe state.
[0100] It will be clear to those having ordinary skill in the art,
after reading the present disclosure, how to subdivide, combine,
take subsets, and otherwise manipulate the operations of method 900
to implement an alternative method that falls within the scope of
the present invention. It is to be further understood that these
operations can be achieved by alternative embodiments that feature
different implementations of the present invention.
[0101] FIG. 10 depicts the salient operational states of enhanced
propulsion circuit 301-j. FIG. 10 depicts the typical sequence of
operational states comprising charging state 1001, followed by
drive state 1003, followed by recovery state 1005, followed by the
next charging state 1001--as indicated by the solid-line arrows in
the figure. Safe state 1007 can follow any of the other states, and
charging state 1001 typically follows safe state 1007--as indicated
by the dotted-line arrows in the figure.
[0102] It is to be understood that the present disclosure teaches
some examples of the illustrative embodiments and that many
variations of the invention can easily be devised by those skilled
in the art after reading this disclosure and that the scope of the
present invention is to be determined by the following claims.
* * * * *