WO2009042306A1 - Alliage à mémoire de forme et actionneur - Google Patents

Alliage à mémoire de forme et actionneur Download PDF

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Publication number
WO2009042306A1
WO2009042306A1 PCT/US2008/073330 US2008073330W WO2009042306A1 WO 2009042306 A1 WO2009042306 A1 WO 2009042306A1 US 2008073330 W US2008073330 W US 2008073330W WO 2009042306 A1 WO2009042306 A1 WO 2009042306A1
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WO
WIPO (PCT)
Prior art keywords
actuator
sma
actuated
shape memory
memory alloy
Prior art date
Application number
PCT/US2008/073330
Other languages
English (en)
Inventor
David W. Cripe
Bryan S. Mccoy
Ryan J. Legge
Gerard A. Woychik
Robert P. Campbell
Matthew W. Jenski
Susan M. Olson
Original Assignee
Rockwell Collins, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US11/903,666 external-priority patent/US9136078B1/en
Priority claimed from US11/963,738 external-priority patent/US8051656B1/en
Priority claimed from US11/963,741 external-priority patent/US8220259B1/en
Application filed by Rockwell Collins, Inc. filed Critical Rockwell Collins, Inc.
Publication of WO2009042306A1 publication Critical patent/WO2009042306A1/fr

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H61/00—Electrothermal relays
    • H01H61/01—Details
    • H01H61/0107—Details making use of shape memory materials

Definitions

  • the present invention relates generally to the field of electrical switching devices, and more particularly to an electrical switching device having an actuator mechanism formed of a shape memory alloy (SMA).
  • SMA shape memory alloy
  • Shape memory alloys such as nickel-titanium alloys, copper-aluminum- nickel alloys, copper-zinc-aluminum alloys, iron-manganese-silicon alloys, and the like, are metallic alloys that remember their geometry. After such alloys are deformed, they regain their original geometry by themselves during heating (one-way effect) or, at higher ambient temperatures, simply during unloading (pseudo-elasticity). This capability results from a temperature-dependent martensitic phase transformation from a low-symmetry martensite structure to a highly symmetric crystallographic austenite structure. In most shape memory alloys, a temperature change of only about 10 0 C is necessary to initiate this phase change.
  • Nitinol an acronym for Nickel Titanium Naval Ordnance Laboratories
  • Couplers may employ many such relays (e.g., 30 or more). During manufacture, each relay must be carefully hand soldered and tested. Assemblies of the relays are then functionally tested. The failure of any relay in an assembly may require additional companion relays to be removed and replaced, the assembly to be reassembled, tuned and retested. If a vacuum relay fails in use either before or during flight of the aircraft, the HF antenna coupler must be removed from the aircraft and replaced, which may result in undesirable grounding of the aircraft. Thus, the failure of a single relay is undesirably expensive.
  • a feature of the invention is using the contracting and expanding features of a wire made of a shape memory alloy to pivot or rotate a conductive mechanism into contact with a pair of electrical contacts, to thereby complete an electric circuit therebetween.
  • An advantage of the invention is increased reliability and reduced manufacturing costs when compared to traditional solenoid-based electrical switching device.
  • Electromechanical switches are a globally established, mature design type used in every level of the electronics industry, ranging from power supplies to large high power circuit breakers and isolation circuitry. Electromechanical switches are utilized in environments ranging from relatively benign (e.g., office computers) to severe (e.g., automotive power relays).
  • An actuator can be formed using a material that changes shape in response to application of an external force and that returns to a predictable shape after the force is removed.
  • a material that changes shape in response to application of an external force and that returns to a predictable shape after the force is removed.
  • SMA as described above.
  • SMAs typically change shape in response to the application of heat and return to the same or substantially the same shape after the heat source is removed.
  • an SMA will change shape in response to a current passing through the SMA (e.g. where the current passing through the SMA heats the SMA).
  • the present application overcomes many of the problems of the prior techniques applied to SMA actuators, and disproves the generally held belief that an SMA based actuator could not be created which is both responsive and has a sufficient life.
  • the present invention relates to an actuator that comprises a shape memory alloy element configured to change shape such that changing shape causes the actuator to actuate.
  • the actuator further comprises a power circuit configured to provide a power signal that causes the shape memory alloy to change shape.
  • the actuator further comprises a circuit configured to control a power source to apply a second power signal that causes the shape memory alloy to be in a pre-actuated state.
  • FIG. 1 is a perspective view illustrating an electrical switching device having a pivoting actuator assembly according to an embodiment of the invention
  • FIG. 2 is a sectional view taken along line 2 — 2 in FIG. 1 ;
  • FIG. 3 is a sectional view taken along line 3 — 3 in FIG. 1;
  • FIG. 4 is a top plan view of a contacting portion of the electrical switching device shown in FIG. 1;
  • FIG. 5 is a side elevational view of a non-conductive shaft used in the electrical switching device of FIG. 1;
  • FIG. 6 is a perspective view of various internal components of the electrical switching device of FIG. 1;
  • FIG. 7 is a perspective view illustrating an electrical switching device having a pivoting actuator assembly according to another embodiment of the invention.
  • FIG. 8 is a sectional view taken along line 8 — 8 in FIG. 7;
  • FIG. 9 is a top plan view of a contacting portion of the electrical switching device shown in FIG. 7;
  • FIG. 10 is a perspective view of various internal components of the electrical switching device of FIG. 7;
  • FIG. 11 is a top plan view of various internal components of the electrical switching device of FIG. 7;
  • FIGS. 12A and 12B illustrate an embodiment of a shape memory alloy (SMA) based switch, wherein the SMA responds to an input stimulus current by changing its length;
  • SMA shape memory alloy
  • FIGS. 13A and 13B illustrate an embodiment of a shape memory alloy (SMA) based switch, wherein the SMA responds to an input stimulus current by changing its shape;
  • SMA shape memory alloy
  • FIGS. 14A and 14B illustrate an embodiment of a shape memory alloy (SMA) based switch, wherein two SMA' s are employed on each end of the switch;
  • SMA shape memory alloy
  • FIG. 15 is a flow diagram illustrating the basic steps performed by a method to calculate an input stimulus current in accordance with the invention.
  • FIG. 16 is a flow diagram of a method for controlling an SMA actuator according to one embodiment
  • FIG. 17 is a block diagram of a system including an SMA actuator according to one embodiment
  • FIG. 18 is a block diagram of an SMA actuator according to one embodiment.
  • FIG. 19 is a cladded SMA element according to one embodiment;
  • FIG. 20 is a cladded SMA element according to one embodiment
  • FIGS. 2 IA-D are illustrations of a switch including an SMA actuator according to one embodiment
  • FIGS. 22A-D are illustrations of SMA actuator positions according to one embodiment
  • FIG. 23 is an illustration of a switch including an SMA actuator according to one embodiment
  • FIG. 24 is an illustration of a switch including an SMA actuator according to one embodiment
  • FIGS. 25 A-B are illustrations of a switch including an SMA actuator according to one embodiment
  • FIG. 26 is an isometric view illustrating an electrical switching device having a pivoting actuator assembly in accordance with an exemplary embodiment of the present invention, wherein the actuator mechanism is shown in a neutral or non-actuated position;
  • FIG. 27 is a cross-sectional side elevation view of the electrical switching device shown in FIG. 26, wherein the actuator assembly is shown in a non-actuated position;
  • FIG. 28 is a cross-sectional side elevation view of the electrical switching device shown in FIGS. 26 and 27, wherein the actuator assembly is shown in an actuated position;
  • FIG. 29 is an isometric view illustrating a electrical switching device having a rotary actuator assembly in accordance with an exemplary embodiment of the present invention
  • FIG. 30 is a cross-sectional side elevation view of the electrical switching device shown in FIG. 29, wherein the actuator assembly is shown in a non-actuated position;
  • FIG. 31 is a cross-sectional side elevation view of the electrical switching device shown in FIGS. 29 and 30, wherein the actuator assembly is shown in an actuated position;
  • FIG. 32 is an isometric view illustrating a electrical switching device having a rotary actuator assembly in accordance with anexemplary embodiment of the present invention
  • FIG. 33 is a cross-sectional side elevation view of the electrical switching device shown in FIG. 32, wherein the actuator assembly is shown in a non-actuated position;
  • FIG. 34 is a cross-sectional side elevation view of the electrical switching device shown in FIGS. 32 and 33, wherein the actuator assembly is shown in an actuated position;
  • FIG. 35 is a cross-sectional side elevation view illustrating a electrical switching device having an actuator assembly including a filament actuator in accordance with an exemplary embodiment of the present invention.
  • FIG. 36 is a partial cross-sectional side elevation view of the electrical switching device shown in FIG. 10, further illustrating linear movement of the movable contact assembly by the actuator.
  • FIGS. 1-11 illustrate exemplary electrical switching devices, which employ actuator mechanisms formed of a shape memory alloy (SMA) in accordance with exemplary embodiments of the present invention.
  • SMA shape memory alloy
  • each electrical switching device 100 illustrated comprises a vacuum tube housing 102 connected to a base 103.
  • the housing has one or more non- actuated electrical contacts 104 and 106 mounted therein.
  • An actuator assembly 108 is supported within the housing 102 and base 103.
  • the actuator assembly 108 includes a movable contact structure for engaging the non-actuated electrical contacts 104 and 106 to complete a circuit between the contacts 104 and 106 so that electrical current may flow between the contacts 104 and 106.
  • the actuator assembly 108 moves the movable contact structure between an actuated position, wherein the movable contact structure engages the non-actuated electrical contacts 104 and 106 and a non-actuated position, wherein the movable contact structure is disengaged from the contacts 104 and 106.
  • the non-actuated contacts 104 and 106 and the movable contact structure are formed of a conductive material such as copper, rhodium, a tungsten/molybdenum alloy, or the like.
  • the actuator assembly 108 further includes a shape metal alloy (SMA) element housed substantially within base 103 and formed of a shape metal alloy which changes shape upon the application of an electric current (e.g., when heated by the application of an electric current).
  • SMA shape metal alloy
  • the application of an electrical current to the SMA element causes the SMA element to move the movable contact structure to either engage or disengage the non-actuated electrical contacts 104 and 106 so that the flow of an electric current through the contacts 104 and 106 is either allowed or inhibited.
  • the SMA element is formed of a nickel-titanium alloy such as Nitinol.
  • shape memory alloy SMA
  • shape memory alloy may include, but are not necessarily limited to, copper-aluminum-nickel alloys, copper-zinc-aluminum alloys, iron- manganese-silicon alloys, and the like.
  • shape memory alloys SMA
  • the actuator may employ a shape memory alloy (SMA) exhibiting a one-way shape memory effect.
  • the SMA element upon being heated by the application of an electric current, acquires a predetermined shape, geometry or length without the application of an external force.
  • a return mechanism may be provided to return the actuator to its original position and condition prior to heating.
  • the return mechanism may be mechanical (such as a spring), hydraulic, pneumatic, or the like.
  • the SMA element may employ a shape memory alloy (SMA) exhibiting a two-way shape memory effect, wherein the SMA element acquires two different shapes: one a low temperature shape when no electrical current is applied, and the other a high temperature shape acquired upon application of an electrical current.
  • SMA shape memory alloy
  • FIGS 1-6 illustrate a vacuum relay electrical switching device 100 having a pivoting actuator assembly 108 according to an embodiment of the invention.
  • the electrical switching device 100 includes a vacuum tube housing 102 comprising a tubular insulator 114 formed of an electrically insulating material such as glass, a ceramic, a sufficiently electrically insulating thermoset or thermoplastic, or the like.
  • an outer case 116 (e.g., a hollow metal case) may be provided to surround and protect the tubular insulator.
  • a cap 118 is coupled to the insulator 114 via a braze joint, crimp joint, or the like.
  • the volume within the vacuum tube housing 102 (e.g., within the cylindrical volume of the insulator 114) is at least partially evacuated to form a vacuum which functions as a dielectric.
  • the volume within the vacuum tube housing 102 may be filled with a gas such as sulfur hexafluoride (SF6), air, or the like.
  • SF6 sulfur hexafluoride
  • first non-actuated contact 104 is supported in the insulator 114 of the housing 102 near the middle of the insulator 114.
  • second non-actuated contact 106 is provided adjacent the cap 118 of the insulator 114.
  • Tabs 120, 122 couple the non-actuated contacts 104, 106 to external circuits (not shown).
  • First non-actuated contact 104 is shown in detail in Figure 4, and includes first and second arms 104a, 104b each of which having a curvature substantially similar to the curvature of vacuum tube housing 102.
  • the first non-actuated contact also has a contacting portion 105 that comprises first and second intersecting portions 105 a, 105b. The first and second intersecting portions are movable when force is placed thereupon.
  • Second non-actuated electrical contact 106 is constructed similarly to first non-actuated electrical contact 104.
  • the actuator assembly includes a non-conductive shaft 123 ( Figure 3) having a length somewhat longer than the length of insulator 114.
  • the first end 123a of shaft 123 is disposed adjacent cap 118.
  • the second end 123b of the shaft includes a pivot axle 124 and a semi-circular saddle 125 disposed thereon.
  • Shaft 123 has first and second shaft contacts 126, 127 that extend from the shaft.
  • the shaft contacts are electrically conductive and, as shown in Figure 5, are electrically connected to each other through a conductive wire 128 that passes through a hollow portion 130 of shaft 123.
  • Base 103 is depicted in detail in Figure 6.
  • Base 103 is preferably made of a thermoset material and is molded and/or machined to define its structure as described herein.
  • Base 103 includes an axle support structure 132 into which pivot axle 124 is installed.
  • Axle support structure 132 prevents pivot axle 124 from all movement except for rotation about axis A.
  • a spring 134 is disposed in a spring recess 136 formed in base 103.
  • Spring 134 is formed generally parallel to non-conductive shaft.
  • the SMA element is a wire 137 formed of a shape memory alloy disposed substantially within base 103.
  • the first and second ends 137a, 137b of wire 137 are crimped with a conductive material and are housed in first and second crimp recesses 138, 140 that are formed in base 103.
  • Wire 137 is selected to have a length sufficient to wind around saddle 125 of non-conductive shaft 123.
  • the diameter of wire 137 may be selected according to required performance requirements. For a relay switch used in an antenna coupler a wire diameter of 0.02 inches has been found to have sufficient strength to actuate switching device 100.
  • First and second crimped ends 137a, 137b of wire 137 are electrically coupled to first and second pins 142, 144, respectively, which are mounted to the bottom of base 103 and extend from the outer surface of the bottom of the base so that a first electric current may be applied to the wire.
  • the presently disclosed embodiment is assembled by first placing spring 134 into spring recess 136. Pivot axle 124 of non-conductive shaft 123 is placed into axle support structure 132 of base 103. The first crimped end 137a of wire 137 is placed into first crimp recess 138. Wire 137 is threaded through a first wire groove 146 that is formed in base 103. Non-conductive shaft 123 is rotated so that second end 123b presses down against spring 134. Wire 137 is placed upon saddle 125, which is preferably grooved along its perimeter so that the wire is maintained thereon.
  • first and second shaft contacts 126, 127 will be adjacent to, but will not touch, contacting portions 105 of first and second non-actuating electrical contacts 104, 106, respectively.
  • Base 103 is crimped or otherwise sealed to tubular insulator 114, and the internal volume of the tubular insulator may be evacuated as previously discussed.
  • a first electric current is applied to wire 137 through first and second pins 142, 144.
  • the wire contracts and shortens, urging saddle 125 against spring 134 and pivoting non-conductive shaft 123 downward at pivot axle 124.
  • the non-conductive shaft 123 moves toward first and second non-actuated electrical contacts 104, 106, such that first and second shaft contacts 126, 127 engage and move along the surfaces of the contacting portions 105 of the respective first and second non-actuated electrical contacts.
  • a circuit is thereby completed between first and second non-actuated electrical contacts 104, 106 so that a second electric current may flow therebetween.
  • the movement of the shaft contacts along the contacting portions 105 acts as a 'brushing' electrical contact that helps prevent oxidation that readily occurs on high-voltage HF electrical contacts.
  • contraction of the wire ceases and the wire is allowed to expand as urged by spring 134.
  • the spring being no longer compressed by the wire, extends and pivots the non-conductive shaft 123 upward, which pivots the first and second shaft contacts 126, 127 away from the first and second non-actuated electrical contacts, respectively, until there is no engagement therebetween.
  • the circuit between the first and second non-actuated electrical contacts is opened, and flow of the second electric current therebetween is inhibited.
  • the diameter (gauge) of wire 137 and the shape memory alloy (SMA) material from which the wire is fabricated may be selected to achieve the relay performance attributes required by the application in which the vacuum relay electrical switching device 100 is used.
  • FIGs 7-11 illustrate a second vacuum relay electrical switching device 100' having a rotating actuator assembly 108' in accordance with an exemplary embodiment of the present invention.
  • the electrical switching device 100' again includes a vacuum tube housing 102 attached or connected to a base 103 ( Figure 7).
  • Housing 102 comprises a tubular insulator 114 and an optional outer case, which is not depicted in this embodiment.
  • Tubular insulator 114 is formed of an electrically insulating material such as glass, a ceramic, a sufficiently insulating thermoset or thermoplastic, or the like.
  • a cap 118 is coupled to the insulator 114.
  • the volume within the vacuum tube housing 102 may be at least partially evacuated to form a vacuum which functions as a dielectric.
  • the volume within the vacuum tube housing may be filled with a gas such as sulfur hexafluoride (SF6), air, or the like.
  • SF6 sulfur hexafluoride
  • a first non-actuated electrical contact 104' is provided adjacent the cap 118 of the insulator 114, while a second non-actuated electrical contact 106' is supported in the insulator 114 near the middle of the insulator 114.
  • Tabs 120, 122 couple the non-actuated electrical contacts 104, 106, to external circuits (not shown).
  • First non-actuated contact 104' is shown in detail in Figure 9, and includes first and second arms 104 'a, 104'b, each of which having a curvature substantially similar to the curvature of vacuum tube housing 102.
  • the first non-actuated contact also has a contacting portion 105' that comprises an insert 105 'a having a surface of gradually reduced curvature when compared to the curvature of the first and second arms 104 'a, 104'b.
  • Insert 105 'a is designed to be flexible or movable when force is placed thereupon.
  • Second non-actuated electrical contact 106' is constructed similarly to first non-actuated electrical contact 104'.
  • the actuator assembly includes a wire 137, made of an SMA material, and attached to base 103.
  • the wire 137 is electrically coupled to first and second pins 142, 144 that are mounted to the bottom of base 103 and extend from the outer surface of the bottom of the base.
  • the wire is threaded around two grooved extensions 150a, 150b formed on a spindle 150 ( Figure 11).
  • the spindle is mounted in or upon the base and rotatable with respect thereto.
  • First and second springs 152, 154 are attached to spring mounting bosses 156, 158 on base 103 and on bosses 150c, 15Od of spindle 150.
  • Bosses 150c, 15Od are shown as being part of grooved extensions 150a, 150b, respectively.
  • a keyed non-conductive shaft 160 is inserted into a correspondingly keyed opening 15Oe of the spindle such that the spindle and shaft rotate together.
  • Keyed shaft 160 is attached to a hollow cylindrical drum 162.
  • the drum 162 has a conductive strip 164 applied thereon.
  • Conductive strip 164 has a length equal or greater to the distance between the first and second non-actuated electrical contacts.
  • the drum substantially fills the cylindrical volume of insulator 114, although the drum is designed to rotate even when conductive strip 164 contacts first and second non-actuated electrical contacts 104', 106'.
  • spindle 150 is placed into or upon base such that the spindle is free to rotate.
  • First and second springs 152, 154 are attached to spring mounting bosses 156, 158 on base 103 and on bosses 150c, 15Od of spindle 150.
  • the first crimped end 137a of wire 137 is placed into a first crimp recess 138.
  • Wire 137 is threaded through a first wire groove 146 that is formed in base 103, as well as around grooved extensions 150a, 150b of the spindle. The spindle is rotated against the force of the first and second springs.
  • Wire 137 is then threaded through a second wire groove 148 that is formed in base 103, and second crimped end 137b of the wire is placed into second crimp recess 140. The spindle is then released, permitting first and second springs 152, 154 urge spindle to rotate until wire 137 is taut.
  • Non-conductive shaft 123 is placed into keyed opening 15Oe.
  • Tubular insulator 114 is placed over drum 162, which is attached to the non-conductive shaft, such that conductive strip 164 does not contact first and second non-actuating electrical contacts 104', 106'.
  • Base 103 is crimped or otherwise sealed to tubular insulator 114, and the internal volume of the tubular insulator may be evacuated as previously discussed.
  • a first electric current is applied to wire 137 through first and second pins 142, 144.
  • the wire contracts and shortens, which urges the grooved extensions 150a, 150b toward each other, thereby causing rotation of spindle 150 and the non-conductive shaft 123 keyed thereto.
  • Rotation of non-conductive shaft 123 causes drum 162 to rotate toward first and second non-actuated electrical contacts 104', 106', such that conductive strip 164 engage and move along the contacting surfaces of the first and second non- actuated electrical contacts.
  • a circuit is thereby completed between first and second non- actuated electrical contacts 104', 106' so that a second electric current may flow therebetween.
  • first and second non-actuated electrical contacts act as a 'brushing' electrical contact that helps prevent oxidation that readily occurs on high-voltage HF electrical contacts.
  • the diameter (gauge) of wire 137 and the shape memory alloy (SMA) material from which the wire is fabricated may be selected to achieve the relay performance attributes required by the application in which the vacuum relay electrical switching device 100' is used.
  • wire 137 is discussed as being wrapped once around saddle 125, and in the second embodiment the wire is threaded once around grooved extensions 150a, 150b on spindle 150.
  • the wire may be wrapped a plurality of times around the saddle or the extensions.
  • the composition, size, and/or shape of the wire may be varied.
  • the disclosed coil springs 134, 152, 154 function to dampen vibrations as well as urge wire 137 to expand to its original length when electric current ceases to flow therethrough.
  • the coil springs may therefore be replaced by other types of springs, such as a torsion spring, or by other types of mechanisms that provide satisfactory dampening and expanding reactions, such as a plug or element made of rubber, rubberized material, foam, or the like.
  • the invention has been described as a relay switch relying upon the contracting and expanding characteristics of an SMA wire.
  • An advantage of the invention is that the relay switch's reliability increases when compared to traditional solenoid-based switches.
  • a relay switch using an SMA wire to actuate a switch is more reliable than a solenoid using magnetism to actuate the same switch.
  • an SMA wire With an SMA wire, the mechanics of the relay are stable.
  • Another advantage is that with the solenoid replaced by the SMA wire, the relay switch design becomes less complicated, thereby reducing manufacturing costs.
  • Another advantage is that, when compared to a solenoid-based design, the cost of raw materials of the invention are not highly dependent on wildly fluctuating prices of commodities such as copper. Price stability is therefore much easier to achieve.
  • Still another advantage is that with the simple design and the elimination of the copper-based solenoid, manufacturing yields substantially increase.
  • SMA-based electromechanical switches may be employed to provide a switch with improved responsiveness, repeatability and reliability.
  • a mechanical response generated by heating an SMA with an electrical current may be used to bring contacts together, thereby making or breaking an electrical connection.
  • SMA-based switches may have distinct advantages over solenoids and motors. By replacing solenoids and motors with SMA-based switches, critical design characteristics may be improved, such as decreasing cost, size and weight requirements.
  • the electromechanical switch of the present invention may create a controlled electrical stimulus current that may actuate an SMA-based electromechanical switch quickly, while still preserving the integrity of the SMA-based switch. Further, with a wire filament embodiment of an SMA-based switch design, there is a broader opportunity for applying SMA' s to high performance electromechanical switch implementations. [0077] Referring now to FIGS. 12A and 12B, there is shown an SMA-based switch 200.
  • the SMA-based switch comprises a first conductive portion 202 and a second conductive portion 204.
  • the first conductive portion 202 further comprises a first conductive stationary end 208 and a first conductive floating end 210, connected by an SMA 212 material in a wire filament implementation.
  • An input stimulus current 214 is applied to the SMA 212 to produce a heating response in the SMA 212 in which the SMA 212 changes its state (e.g. length and/or shape).
  • a temperature change may cause the SMA 212 to change its length (e.g. contracts or extends), urging motion of the first conductive floating end 210 towards (or away from) the second conductive portion 204 along a path 216.
  • the SMA 212 is contracted (in length), as shown in FIG.
  • the input stimulus current 214 is calculated for a given response time to meet the timing requirements.
  • the calculated input stimulus current 214 produces a fast heating response in the SMA 212 and does not deleteriously affect its structure.
  • the SMA-based switch is capable of achieving: 1) actuation times of 5 milliseconds; 2) known repeatability of actuation in excess of 3 million of cycles or more; and 3) higher reliability of SMA-based switch (relay) design with use of a controlled and known electrical input.
  • the amount of energy over time flowing through the input stimulus current 214 into the SMA 212 contributes to the SMA' s fast heating response.
  • the wave shape of the stimulus current is not a factor to the response time in the SMA 212. It is contemplated that the wave shape of the input stimulus current 214 may be square, saw tooth, sine, pulse- width modulation (PWM), as well as other various shapes. The timing requirement may be satisfied so long as the energy over time provided by the input stimulus current 214 satisfies the calculated value for the given response time, regardless of the wave shape of the current. [0080] It is further contemplated that the input stimulus current 214 may be increased or decreased in order to satisfy different response time requirements.
  • an input stimulus current value may be calculated to meet the requirement. If the response time requirement is later decreased to 5 milliseconds, a stronger input stimulus current value may be calculated, which satisfies the new requirement without changing other parts of the switch. Alternatively, if the response time requirement was later extended to 7 milliseconds, a reduced input stimulus current value may be calculated to satisfy the extended response requirement, with less energy consumption while still meeting the timing requirement.
  • SMA 212 and input stimulus current 214 may reside within a circuit loop that is isolated from a conductive path being connected/disconnected.
  • SMA 212, input stimulus current 214 and the conductive path may be unisolated.
  • the SMA 212 employed in the SMA-based switch 200 may change its shape when responding to a temperature change.
  • the SMA 212 When the SMA 212 is in a generally linear shape, it holds the first conductive floating end 210 away from the second conductive portion 204, as shown in FIG. 13 A. In this arrangement, current flow is interrupted and the switch 200 is in a disconnected state.
  • the SMA 212 When the SMA 212 is in a generally semi-circular shape and the first conductive floating end 210 contacts the second conductive portion 204, as shown in FIG. 13B, current flow is allowed and the switch 200 is in a connected state.
  • the SMA 212 may be of different shapes, forms, and/or lengths, so long as it responds to temperature changes which in turn urge motion of the first conductive floating end 210. It is understood that alternative SMA's may be employed without departing from the scope and spirit of the present invention.
  • the second conductive portion 204 may contain a second conductive stationary end 302 and a second conductive floating end 304, connected by a second SMA 306 material in a wire filament implementation.
  • a second input stimulus current 308 is applied to the second SMA 306 to produce heating response in the second SMA 306.
  • temperature change can cause the second SMA 306 to change its length (e.g. contracts or extends), hence urging motion of the second conductive floating end 304 towards (or away from) the first conductive portion 202 along the path 216.
  • first conductive floating end 210 and the second conductive floating end 304 When the first conductive floating end 210 and the second conductive floating end 304 are not in contact, current flow from the first conductor 106 to the second conductor 218 is interrupted; hence the switch 200 is in a disconnected state. When the first conductive floating end 210 and the second conductive floating end 304 are in contact, current flow is allowed and the switch 200 is in a connected state.
  • the first conductive floating end 210 and the second conductive floating end 304 may establish a connection under various conditions. For example, in an exemplary embodiment, the connection is made if and only if both the first conductive floating end 210 and the second conductive floating end 304 are moved toward the center of the path 216.
  • the electrical connection can be established only when both the first conductive portion 202 and the second conductive portion 204 initiate the connection.
  • the connection can be established if any one of the first conductive floating end 210 and the second conductive floating end 304 is moved toward its counterpart. Therefore the electrical connection can be established by either one of the first conductive portion 202 or the second conductive portion 204. It is understood that alternative designs may be employed without departing from the scope and spirit of the present invention.
  • the second SMA 306 and the second input stimulus current 308 in the second conductive portion 204 may operate independently from their counterparts in the first conductive portion 202.
  • the input stimulus current 214 may have a first value to satisfy a given response time
  • the second input stimulus current 308 may have a different value in order to satisfy a different response time. This allows independent control by both ends of the switch, with possibly different response time requirements.
  • the input stimulus current 214 is calculated for a given response time requirement.
  • An equation derived from the First Law of Thermodynamics is used to describe the thermodynamic characteristics of SMA in general, and is shown as follows:
  • a first constant C 1 and a second constant C 2 represent two constants in the SMA-based switch 200 design.
  • An experimental input stimulus current / represents an input stimulus current provided to the SMA 212 which will be used to calculate the desired input stimulus current 214.
  • a state changing temperature T ON is a temperature at which the SMA 212 changes state (e.g. length and/or shape).
  • An ambient operating temperature T AMB is an ambient operating temperature of the SMA-based switch 200.
  • An experimental actuation time (response time) t is the amount of time takes for the SMA 212 to respond to a given experimental input stimulus current.
  • step 402 the state changing temperature T ON is determined.
  • the state changing temperature T ON varies depending on the specific material used in the SMA 212.
  • the value of the state changing temperature T ON may y be determined. For example, by gradually increasing (or decreasing) the temperature of the SMA 212 and determining the temperature when the SMA 212 changes state, the state changing temperature T ON can be determined.
  • step 404 the ambient operating temperature T AMB of the SMA-based switch is determined. This can be determined, for example, by measuring the temperature using a temperature measuring instrument.
  • a first actuation time t ⁇ in response to a first input stimulus current Z 1 is determined.
  • the first actuation time can be measured, for example, by measuring the amount of time needed for the SMA 212 to respond to the first input stimulus current.
  • a second actuation time h in response to a second input stimulus current / 2 is determined.
  • the first constant and the second constant are determined by solving a system of two equations with two unknowns.
  • the equations are obtained by plug-in values of the variables determined in the above steps into the equation. For instance, the state changing temperature T ON an d the ambient operating temperature T AMB have already been determined and they stay unchanged in the first equation and the second equation.
  • the first actuation time t ⁇ is used in place of the experimental actuation time, while the first input stimulus current Z 1 is used in place of the experimental input stimulus current.
  • the second actuation time h is used in place of the experimental actuation time, while the second input stimulus current / 2 is used in place of the experimental input stimulus current.
  • the value of the first constant C 1 and the second constant C 2 can be determined by solving the system of two equations.
  • the desired input stimulus current 214 is calculated by solving one equation with one unknown (the input stimulus current 214).
  • the equation is obtained by substituting values for the variables as determined in the above steps into the equation. For instance, the state changing temperature T ON has been determined in step 402.
  • the ambient operating temperature T AMB has been determined in step 404.
  • the first constant C 1 and the second constant C 2 have been determined in step 410.
  • the desired actuation time (a given response time requirement) is known and is used in place of the experimental actuation time t.
  • the value of the experimental actuation time t is set to 6 milliseconds. Therefore the value of the desired input stimulus current 214 can be determined by solving the resulting equation. This equation may be solved repeatedly for different desired actuation times to provide input currents which satisfy these actuation times.
  • the present application overcomes many of the problems of the prior techniques applied to SMA actuators, and disproves the generally held belief that an SMA based actuator could not be created which is both responsive and has a sufficient life.
  • One technique used in many embodiments is to apply a base current during non- actuation periods to maintain the SMA element of the SMA actuator in a pre-actuated state.
  • the pre-activated state of the SMA actuator may be its rest position, or may be an intermediate position that is between the rest position and the actuated position.
  • additional current or an alternate current is supplied in order to bring the SMA element to its actuated state.
  • Another technique developed was to monitor criteria related to the SMA element in order to better control the SMA element. For example, a criteria related to the shape of the SMA element may be monitored in order to control the base current being applied, may be monitored to control the actuation current being applied, etc.. [0096] While any number of criteria can be monitored, it was discovered that at least some SMA elements have a noticeable change in impedance as the SMA element changes shape. It was even further discovered that this effect becomes even more noticeable when the SMA element is at least partially ferromagnetic (e.g.
  • this impedance to an AC current can be used actively and/or passively in order as one means of controlling the base current (e.g. a DC current) applied to the SMA element.
  • AC current e.g. an AC current provided at an RF frequency
  • This AC current may be used with the base current technique described above (i.e. the AC current may be applied on top of the base current when actuation is desired) or may be used independently.
  • an SMA actuator may be reliably actuated in under 50 ms (even under 10 ms) without substantially degrading the performance of the actuator (e.g. may provide actuation in under 50 ms for over a million cycles), contrary to the prevailing assessment in the art.
  • a method for actuating a shape memory alloy (SMA) actuator 252 comprises determining whether to actuate the actuator at block 10. The determination at block 10 may be based on an input from a switch, a control circuit 260 (e.g. a processing circuit), etc. If the actuator is not being actuated, the method may continue to monitor whether to actuate the actuator at block 10, or may monitor a state of the SMA at block 12 in order to control the SMA actuator at block 14. [0100] Controlling the SMA actuator 252 may involve applying power from a power circuit 212 at block 14 in order to maintain the SMA element 266 in a pre-actuated state.
  • SMA shape memory alloy
  • the pre-actuated state is a state that is between the rest state of the SMA element 266 (e.g. the default state of the SMA element) and the actuated state of the SMA element 266 (the state of the SMA element 266 at which the actuator 252 is actuated).
  • the pre-actuated state may be a rest shape state (see, e.g. state 720 of Fig. 22A) in which the SMA element 266 is essentially the same shape as the SMA element 266 in its rest state, or may be a transition shape state (see, e.g. state 730 of Fig. 22B) in which the SMA element 266 is a different shape than the shape of the SMA element 266 in the rest state but is also a different shape than the actuated state shape (see, e.g. state 740 of Fig. 22C).
  • Applying power from a power circuit 262 at block 14, may include applying a base current configured to maintain the SMA element 266 at a pre-actuated state.
  • a base current applied at block 14 may be directly applied to the SMA element 266 (e.g. a current running through the SMA element 266) and/or may be applied to an element (not illustrated) such as a heating element (e.g. a resistor, heating coil, etc.) in proximity to the SMA element 266.
  • a base power from power circuit 262 may be a direct current signal, an alternating current signal, and/or some other type of signal.
  • the base power may be applied continuously or may be applied discontinuously (e.g. in bursts such as pulses).
  • the base power may be applied at a fraction of the actuation power (the minimum continuous current required to first actuate the SMA and maintain it in an actuated state) such that less power needs to be applied to actuate the actuator.
  • the base power may be at least 10%, at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, and/or at least 90% of the actuation power (i.e. is the amount of power that effectively reduces an amount of actuation power required to actuate the actuator by the listed percentage).
  • the base power may be up to 90%, up to 80%, up to 70%, up to 60%, up to 50%, up to 40%, up to 30%, and/or up to 20% of the actuation power.
  • the base power may be less than 10% or more than 90% of the actuation power.
  • the base power is about 80% of the actuation power and includes at least a direct current signal portion. In another exemplary embodiment, the base power is about 30% of the actuation power and includes a direct current signal portion.
  • the type and/or amount of power applied at block 14 may be based on a criteria related to the state of the SMA actuator 252 that is monitored at block 12.
  • the criteria monitored may be directly related to the state of the SMA element 266 and/or may indirectly provide information suggestive of the state of the SMA element 266.
  • an increase in impedance and/or resistance of the SMA element 266 to a signal passed through the SMA element 266 may be directly related to a change in shape of the SMA element 266.
  • a change in the ambient temperature around (or direct temperature of) the SMA element 266 may indirectly suggest that the SMA element 266 will change shape if the measured temperature is around the temperature at which the SMA element 266 changes shape.
  • an RF signal is applied along the SMA element 266 such that at least a portion of the RF signal passes through the SMA element 266.
  • the impedance to the RF signal is monitored at block 12 by a monitoring circuit 264, and is used to control application of a base power from power circuit 262 at block 14.
  • a DC signal is applied along the SMA element 266 such that at least a portion of the DC current passes through the SMA element 266.
  • the resistance to the DC signal is monitored at block 12 by a monitoring circuit 264, and is used to control application of a base power from power circuit 262 at block 14.
  • a monitoring circuit 264 is used to monitor the temperature of (e.g.
  • Steps 10-14 may be continually repeated such that the SMA element 266 is dynamically maintained at a pre-actuated state.
  • step 12 may be omitted such that a constant base power is applied at block 14.
  • an actuation power is applied from a power circuit 262 at block 18 (e.g. using the same or different portions of a power circuit used to apply power at block 14) in order to actuate the SMA actuator 252.
  • the actuation power applied at block 18 may have any of the characteristics of the power discussed above with respect to block 14 (e.g. DC, AC, RF, continuous, discontinuous, etc.).
  • the power applied at block 18 includes a modulated portion.
  • the modulated portion may be modulated at a radio frequency (RF).
  • the actuation power provided at block 18 consists essentially of a modulated (e.g. an RF) signal.
  • the actuation power applied from the power circuit 262 at block 18 may include the full power needed to actuate the SMA actuator 252.
  • the actuation power applied at block 18 is applied on top of the base power applied at block 14 (i.e. the actuation power and base power are both applied such that the combination of powers combines to provide enough power to actuate the actuator 252).
  • the actuation power if applied alone, would not be enough power to actuate the actuator 252.
  • the actuation power applied at block 18 may be the same as or different than the base power applied at block 14.
  • the base power consists primarily (e.g. at least 51%), mostly (e.g. at least 70%), and/or essentially (e.g. at least 85%) of a direct current signal, while the actuation power consists primarily, mostly, and/or essentially of an alternating current signal (e.g. an RF signal).
  • the signal applied at block 18 may be based on the monitored state of the SMA actuator 252 determined at block 16.
  • the monitoring at block 16 may be any of the types (or combinations of types) of monitoring discussed above with respect to block 12 and may use common or different monitoring circuits 264 as those used in block 12.
  • the power applied at block 18 may be a determined amount of power needed to maintain the SMA actuator 252 in its actuated state.
  • the determined amount of power may be predetermined (e.g. a fixed amount, an amount based on a criteria unrelated to the SMA element 266, etc.), or may be based on a monitored criteria at block 16.
  • the amount of power applied at block 18 to maintain the SMA actuator 252 in its actuated state may be based on a natural feedback mechanism.
  • an SMA element 266 may be designed to have a high impedance at a point just beyond its initial actuated state such that the amount of an RF actuation power passing through the SMA element is reduced significantly at that point.
  • the power is based on a combination of a determined amount of power and a natural feedback mechanism.
  • the amount of power applied at block 18 to maintain the actuator 252 in its actuated state may be based on the minimum amount of power necessary to maintain the actuator 252 in its actuated state.
  • the amount of power applied from power circuit 262 at block 18 to maintain the actuator in its actuated state may be close to (e.g. within two times) the minimum amount of power, may be essentially (e.g. within one and a half times) the minimum amount of power, or may be about the minimum (e.g. within 10% of the minimum) amount of power needed to maintain the SMA element in its actuated state.
  • Steps 10-20 may be controlled by a control circuit 260 such as a feedback circuit.
  • Control circuit 260 may be implemented as any type of circuit such as an analog control circuit and/or a digital control circuit (e.g. a processing circuit).
  • the functions of control circuit 260 may be implemented in a single control circuit 260 or may be implemented by a number of discrete circuits which are (when taken as a whole) control circuit 260.
  • controlling of actuation at blocks 10 and 20 may be based on a signal from a processor (e.g. a controller or microprocessor) while control of an amount of power at blocks 14 and 18 may be based on a separate (e.g. analog, digital, etc.) feedback circuit.
  • a control circuit configured to perform a function in a claim would include both single circuits and two or more separate circuits unless specifically referred to as a single control circuit in that claim.
  • an exemplary control circuit 260 (Fig. 17) includes a first control circuit portion 312 configured to control a modulated power source 352 over line 386 to provide an actuation power to the SMA element 366 to actuate the SMA actuator 252 (Fig. 17).
  • Control circuit portion 362 may include any control (and other) circuits including a switch, a processor (e.g. a microcontroller or microprocessor), analog signal processing circuitry, etc.
  • the control circuit 260 (Fig. 17) also includes a second control circuit portion 364 configured to control a DC power source 354 to provide a maintenance power to SMA element 366 to maintain SMA element 366 in a pre-actuated state.
  • Control circuit portion 364 may be configured to control power source 354 based on signals received from one or more monitoring circuits 356-360.
  • Control circuit portion 364 could include any control (and other) circuits including rectifier(s), amplifier(s), comparator(s), filter(s), digital signal processing and control circuitry, etc.
  • control circuit portion 362 could additionally (or alternatively) control power source 354 and/or control circuit portion 364 could additionally (or alternatively) control power source 352. Also, in some embodiments, control circuit portion 362 and control circuit portion 364 may share common components such that they form a unitary control circuit 260 (Fig. 17).
  • a power circuit 262 may be configured to supply the power (e.g. a portion of the power, all of the power, etc.) applied at one or both of blocks 14 and 18.
  • Power circuit 262 may be a single power circuit, or may include multiple power circuits which themselves may or may not be supplied from a common power source.
  • power circuit 262 may include a modulated power source 352 (e.g. an RF power source) configured to provide a modulated (e.g. RF) signal to SMA element 366 along line 380 and a DC power source 354 configured to provide a DC signal to SMA element 366 along line 382.
  • Power source 354 may be configured to provide a steady signal or may provide a pulsed or otherwise modulated signal, and power source 352 may provide an alternating current signal. Power source 354 may also be configured to supply power to power source 352 along line 384, which power may be the same as (e.g. voltage, form, etc.) or different than the power provided along line 382.
  • DC power source 354 may include any circuits, such as a conductor line, power processing circuits (e.g. a diode to protect from reverse voltages, switches, filters, etc.), etc.
  • the modulated power source 352 may include any circuits configured to provide modulated power such as an oscillator (e.g. a Colpitts oscillator, a Hartley oscillator, etc.), and/or other circuits (e.g. an amplifier, a variable resistor, a transistor, optocoupler, solid state relay, etc.).
  • monitoring at blocks 12 and/or 16 may involve receiving data from a monitoring circuit 264.
  • Monitoring circuit 264 may include a single monitoring circuit 356-360 (Fig. 18) or may include more than one monitoring circuit 356- 360 (Fig. 18).
  • Monitoring circuit 264 could measure a parameter related to a signal passing through SMA element 266.
  • monitor 356, 358 may be connected in series (or parallel) to SMA element 366 and may be configured to measure a parameter related to the signal passing through SMA element 366 (e.g. before or after the signal has passed through SMA element 366).
  • monitoring circuit 356 and/or 358 may be configured to measure impedance to an RF signal passing through the circuit including SMA element 366 (e.g. by being in series to or in parallel to SMA element 366).
  • the monitoring circuit may include a diode and/or an operational amplifier configured to provide a signal based on the impedance of the circuit comprising the SMA element.
  • Monitoring circuit 264 could be configured to measure a parameter unrelated to a signal passing through SMA element 266.
  • monitoring circuit 264 could include a monitoring circuit 360 configured to measure a parameter related to the SMA element, but not of the SMA element.
  • circuit 360 could include a temperature sensor (e.g.
  • the SMA actuator 252 may be capable of actuating within one second of applying the actuation power at block 18.
  • the SMA actuator 252 may be capable of actuating within about 500 ms, within about 300 ms, within about 100 ms, within about 75 ms, within about 50 ms, within about 40 ms, within about 30 ms, within about 20 ms, within about 15 ms, within about 10 ms, within about 8 ms, within about 7 ms, within about 6 ms, and/or within about 5 ms.
  • an SMA actuator 252 may actuate within one or more of the time limits listed for at least about 100 thousand cycles, at least about 500 thousand cycles, at least about 1 million cycles, at least about 2 million cycles, at least about 3 million cycles, at least about 4 million cycles, and/or at least about 5 million cycles. In other embodiments, the SMA actuator may actuate in more than 500 ms and/or may actuate within a time limit for fewer than 100 thousand cycles.
  • SMA element 266, 366 could be any number of different shape memory alloys.
  • the SMA element may be an alloy that has a memory effect in response to heating.
  • the SMA element 266, 366 may be a ferromagnetic shape memory alloy (FSMA) that is configured to exhibit a shape memory effect in response to the application of a magnetic field (e.g. from an externally generated magnetic field, an internally generated magnetic field generated through the application of an electric current through the SMA element, etc.).
  • the SMA element 266, 366 could have a one-way shape memory (e.g. "remembers" one shape), a two-way shape memory (e.g.
  • the SMA element 266, 366 can have any shape.
  • the SMA element 266, 366 may be rounded (e.g. cylindrical, conical, etc.), may be polygonal (e.g. a rectangular box, a hexagonal box, etc.), may be irregularly shaped, may be symmetrical, may be asymmetrical, etc.
  • SMA element 266, 366 may be a wire-type shape (see, e.g. Figs. 19 and 20).
  • the conductive portion of SMA element 266, 366 may be any size. According to some embodiments, the conductive portion of the SMA element 266, 366 has an average thickness (e.g. diameter, cross-sectional length, etc.) of at least about 0.1 mils, at least about 0.25 mils, at least about 0.5 mils, at least about 1 mil, at least about 2 mils, at least about 3 mils, at least about 4 mils, at least about 5 mils, at least about 6 mils, at least about 8 mils, at least about 11 mils, and/or at least about 13 mils.
  • average thickness e.g. diameter, cross-sectional length, etc.
  • the conductive portion of the SMA element 266, 366 has an average thickness of up to about 22 mils, up to about 17 mils, up to about 12 mils, up to about 10 mils, up to about 9 mils, up to about 8 mils, up to about 7 mils, up to about 5 mils, and/or up to about 3 mils. In other embodiments, the conductive portion of the SMA element may have an average thickness of less than 0.1 mils or more than 22 mils.
  • the shape memory alloy portion of SMA element 266, 366 may be any size. According to some embodiments, the shape memory alloy portion of the SMA element 266, 366 has an average thickness (e.g. diameter, cross-sectional length, etc.) of at least about 0.1 mils, at least about 0.25 mils, at least about 0.5 mils, at least about 1 mil, at least about 2 mils, at least about 3 mils, at least about 4 mils, at least about 5 mils, at least about 6 mils, at least about 8 mils, at least about 10 mils, and/or at least about 12 mils.
  • average thickness e.g. diameter, cross-sectional length, etc.
  • the shape memory alloy portion of the SMA element 266, 366 has an average thickness of up to about 20 mils, up to about 15 mils, up to about 10 mils, up to about 8 mils, up to about 7 mils, up to about 6 mils, up to about 4 mils, and/or up to about 2 mils. In other embodiments, the shape memory alloy portion of the SMA element may have an average thickness of less than 0.1 mils or more than 20 mils. [0128] The SMA element 266, 366 can have any length (e.g. longest dimension).
  • the SMA element 266, 366 has a length of at least about 0.01 inches, at least about 0.05 inches, at least about 0.1 inches, at least about 0.5 inches, at least about 0.75 inches, at least about 1 inch, at least about 1.5 inches, at least about 2 inches, at least about 3 inches, and/or at least about 5 inches.
  • the SMA element has a length of up to about 10 inches, up to about 7.5 inches, up to about 5 inches, up to about 3 inches, up to about 1.5 inches, up to about 1 inch, and/or up to about 0.5 inches.
  • the SMA element may have a length of less than 0.01 inches or more than 10 inches.
  • the actuation temperature of the SMA element 266, 366 may any temperature suitable for the application and/or environment in which the actuator will be used. According to some embodiments, the actuation temperature of the SMA element 266, 366 may be at least about 2 0 C, at least about 5 0 C, at least 10 0 C, at least 20 0 C, at least 40 0 C, at least 50 0 C, at least 60 0 C, at least 70 0 C, at least 85 0 C, and/or at least 100 0 C. In some embodiments, the SMA element may have an actuation temperature below 2 0 C.
  • the SMA element could be formed from a shape memory alloy that comprises nickel (e.g. a copper-zinc-aluminum-nickel alloy, a copper-aluminum-nickel alloy, and/or a nickel-titanium alloy), an alloy that comprises iron (e.g. an iron-platinum alloy, and/or an iron-manganese-gallium alloy), and/or from any other shape memory alloy.
  • the SMA element 266, 366 may include a core to 430, 530 (Figs. 19 and 20) formed from a shape memory alloy and a cladding 420, 520 (Figs. 19 and 20) formed from a ferromagnetic material.
  • the SMA element may include a wire (or other element) formed from a shape memory alloy as discussed above (e.g. in the shapes, materials, and sizes discussed above). A ferromagnetic material may then be plated on the shape memory alloy.
  • the ferromagnetic material may be any ferromagnetic material.
  • the ferromagnetic material may be a material that comprises nickel (e.g. FeNi, Ni, CoNi, NiOFe 2 Os, etc.), a material that comprises iron (e.g. Fe, FeOFe 2 Os, NiOFe 2 Os, MgOFe 2 Os, YsFe 5 ⁇ 12 ), and/or may be any other ferromagnetic alloy (MnSb, MnBi, CrO 2 , MnAs, Gd, Dy, EuO).
  • nickel e.g. FeNi, Ni, CoNi, NiOFe 2 Os, etc.
  • iron e.g. Fe, FeOFe 2 Os, NiOFe 2 Os, MgOFe 2 Os, YsFe 5 ⁇ 12
  • MnSb, MnBi, CrO 2 MnAs, Gd, Dy, EuO
  • the cladding material comprises up to about 100%, up to about 80%, up to about 50%, up to about 40%, up to about 35%, up to about 30%, up to about 25%, and/or up to about 20% nickel. In some embodiments, the cladding material comprises at least about 5%, at least about 10%, at least about 15%, at least about 20%, at least about 25%, at least about 30%, at least about 50%, at least about 70%, and/or at least about 90% nickel. In other embodiments, the cladding may comprise less than 5% nickel.
  • the cladding material comprises up to about 100%, up to about 95%, up to about 90%, up to about 85%, up to about 80%, up to about 75%, up to about 50%, and/or up to about 25% iron. In some embodiments, the cladding material comprises at least about 10%, at least about 30%, at least about 45%, at least about 60%, at least about 70%, at least about 80%, and/or at least about 90% iron. In other embodiments, the cladding may comprise less than 10% iron.
  • the cladding material is preferably electrically conductive, ductile, and malleable.
  • a ferromagnetic cladding material may also be selected such that its Curie temperature is greater than the actuation temperature of the shape memory alloy of the SMA element 266, 366.
  • the cladding material may also be selected such that it is magnetostrictive and/or magnetoelastic.
  • the SMA element 266, 366 may be configured such that a change in shape of the SMA element 266, 366 causes a change (e.g. increase or decrease) in the resistance and/or impedance of the cladding material (e.g. changes its impedance to an AC and/or an RF signal) when the SMA element changes shape.
  • Some alloys e.g. 80% Ni, 20% Fe
  • Other alloys e.g.
  • Ni, 67% Fe may or may not be as advantageous (but may be included in an SMA element) if their Curie temperature is around the actuation temperature of the SMA element 266, 366.
  • Examples of magnetostrictive properties for alloys based on their composition are known. See, e.g. "Ferromagnetism”, by Bozorth, published in 1951, the disclosure of which is hereby incorporated by reference.
  • Examples of Curie temperatures for alloys based on their composition are known. See, e.g. See, e.g. "Ferromagnetism", by Bozorth, published in 1951, the disclosure of which is hereby incorporated by reference.
  • the cladding may have a thickness of at least about 1%, of at least about 5%, at least about 10%, at least about 15%, at least about 20%, at least about 30%, at least about 50%, at least about 70%, at least about 80%, at least about 90%, at least about 100%, and/or at least about 120% of the thickness of the core (e.g. the shape metal alloy portion of the SMA element 266, 366).
  • the core e.g. the shape metal alloy portion of the SMA element 266, 366.
  • the cladding has a thickness of up to about 250%, up to about 200%, up to about 170%, up to about 150%, up to about 140%, up to about 130%, up to about 120%, up to about 115%, up to about 110%, up to about 105%, up to about 95%, up to about 90%, up to about 80%, up to about 70%, up to about 60%, up to about 50%, up to about 40%, up to about 30%, up to about 20%, up to about 15%, and/or up to about 10% of the thickness of the core 430.
  • the cladding may have a thickness of more than 250% or less than 1% of the thickness of the core.
  • the cladding has a thickness of at least about 0.1 mils, at least about 0.2 mils, at least about 0.3 mils, at least about 0.4 mils, at least about 0.5 mils, at least about 0.7 mils, at least about 1 mil, at least about 2 mils, at least about 3 mils, at least about 4 mils, at least about 5 mils, at least about 6 mil, at least about 7 mils, and/or at least about 8 mils.
  • the cladding 420 has a thickness of up to about 30 mils, up to about 20 mils, up to about 17 mils, up to about 15 mils, up to about 13 mils, up to about 12 mils, up to about 10 mils, up to about 8 mils, up to about 6 mils, up to about 5 mils, up to about 4 mils, up to about 3 mils, up to about 2 mils, up to about 1 mil, up to about 0.7 mils, up to about 0.5 mils, and/or up to about 0.3 mils.
  • the cladding may have a thickness of less than 0.1 mils or more than 30 mils.
  • a signal is supplied to an SMA element 266, 366 to actuate the SMA element 266, 366
  • at least a portion of the signal may be supplied such that it primarily travels through a ferromagnetic material (e.g. a ferromagnetic cladding, a ferromagnetic alloy, etc.) for at least a portion of the SMA element 266, 366 (i.e. such that a greater amount of that signal portion travels through the ferromagnetic material per volume of the ferromagnetic material than travels through the other portions of the SMA element 266, 366 in the highest conducting state of the ferromagnetic material).
  • a ferromagnetic material e.g. a ferromagnetic cladding, a ferromagnetic alloy, etc.
  • the ferromagnetic material and the RF signal may be configured such that the ferromagnetic material serves as a highly restrictive element to the flow of the RF signal (e.g. restricts at least about 25% and/or at least 50% of the RF signal) at some actuation state beyond the initial actuation state (i.e. the first state of the SMA element 266, 366 at which the SMA actuator 252 is actuated) of the SMA element 266, 366.
  • the ferromagnetic material may serve as a control on the amount of current applied to the SMA element when the SMA element is being maintained in the actuation state (e.g.
  • a signal is supplied to an SMA element 266, 366 to actuate the SMA element 266, 366, at least a portion of the signal may be supplied such that it primarily travels through the cladding material (e.g. a ferromagnetic cladding) for at least a portion of the SMA element 266, 366 (i.e. such that a greater amount of that signal portion travels through the cladding material per volume of the cladding material than travels through the other portions of the SMA element 266, 366 in the highest conducting state of the cladding material).
  • the cladding material e.g. a ferromagnetic cladding
  • the cladding material may be applied as the outer conductive surface of the SMA element 266, 366, and a signal used to actuate the SMA element 266, 366 may comprise an RF signal portion that travels through the exterior conductive portion of the SMA element 266, 366 (e.g. primarily through the cladding material).
  • This signal could also include a direct current portion that travels equally through all conductive parts of the SMA element 266, 366 and/or primarily through the shape memory alloy portion of the SMA element 266, 366.
  • the cladding material and the RF signal may be configured such that the cladding material serves as a highly restrictive element to the flow of the RF signal (e.g.
  • the cladding material may serve as a control on the amount of current applied to the SMA element when the SMA element is being maintained in the actuation state (e.g.
  • an SMA element 416 includes a shape memory alloy core 430 and a ferromagnetic material cladding 420 that extents over substantially all (e.g. essentially all as illustrated, at least about 60%, at least about 75%, and/or at least about 90%) of the core 430.
  • the cladding 420 may have a thickness of at least about 1%, at least about 5%, at least about 10%, at least about 15%, and/or at least about 20% of the thickness of the core 430, or any of the size ranges discussed above. In some embodiments, the cladding 420 has a thickness of up to about 50%, up to about 40%, up to about 30%, up to about 20%, up to about 15%, and/or up to about 10% of the thickness of the core 430, or any of the size ranges discussed above. In other embodiments, the cladding 420 may have a thickness of less than 1% or more than 50% of the thickness of the core 430.
  • the cladding 420 has a thickness of at least about 0.1 mils, at least about 0.2 mils, at least about 0.3 mils, at least about 0.4 mils, at least about 0.5 mils, at least about 0.7 mils, at least about 1 mil, at least about 2 mils, and/or at least about 3 mils, or any of the size ranges discussed above. In some embodiments, the cladding 420 has a thickness of up to about 5 mils, up to about 4 mils, up to about 3 mils, up to about 2 mils, up to about 1 mil, up to about 0.7 mils, up to about 0.5 mils, and/or up to about 0.3 mils, or any of the size ranges discussed above. In other embodiments, the cladding 420 may have a thickness of less than 0.1 mils or more than 5 mils.
  • an SMA element 516 includes a ring of ferromagnetic material cladding 520 around a shape memory alloy core 530.
  • the cladding 520 extends over only a limited portion of the core 530.
  • the SMA element 516 may have multiple rings of cladding 520 along its length.
  • the SMA element 516 may have at least two, at least three, and/or at least four rings, at least five, at least eight, and/or at least ten rings of cladding around core 530.
  • SMA element 516 may have a ring of cladding at least every 0.001 inches, at least every 0.01 inches, and/or at least every 0.1 inches of the SMA element 516.
  • one or more rings of cladding 520 may have a length (e.g. extension along the core 530) of at least about 0.001 inches, at least about 0.005 inches, at least about 0.01 inches, at least about 0.03 inches, at least about 0.05 inches, at least about 0.1 inches, at least about 0.2 inches, and/or at least about 0.3 inches. In other embodiments, one or no rings of cladding 520 have a length greater 0.001 inches.
  • the cladding 520 may have a thickness of at least about 1%, at least about 10%, at least about 30%, at least about 50%, at least about 70%, at least about 80%, at least about 90%, at least about 100%, and/or at least about 120% of the thickness of the core 530, or any of the size ranges discussed above.
  • the cladding 520 has a thickness of up to about 250%, up to about 200%, up to about 170%, up to about 150%, up to about 140%, up to about 130%, up to about 120%, up to about 115%, up to about 110%, up to about 105%, up to about 95%, up to about 90%, up to about 80%, up to about 70%, up to about 60%, and/or up to about 50% of the thickness of the core 530, or any of the size ranges discussed above.
  • the cladding 520 may have a thickness less than 1% or more than 250% of the thickness of the core 530.
  • the cladding 520 has a thickness of at least about 0.5 mils, at least about 1 mil, at least about 2 mils, at least about 3 mils, at least about 4 mils, at least about 5 mils, at least about 6 mil, at least about 7 mils, and/or at least about 8 mils, or any of the size ranges discussed above.
  • the cladding 520 has a thickness of up to about 30 mils, up to about 20 mils, up to about 17 mils, up to about 15 mils, up to about 13 mils, up to about 12 mils, up to about 10 mils, up to about 8 mils, up to about 6 mils, up to about 5 mils, up to about 4 mils, up to about 3 mils, up to about 2 mils, and/or up to about 1 mil, or any of the size ranges discussed above.
  • the cladding 520 may have a thickness of less than 0.5 mils or more than 30 mils.
  • the conductive portion of the SMA element consists essentially of ferromagnetic material.
  • SMA element 266, 366, 416, 516 could include insulation (e.g. to retain heat, electrical insulation, etc.) and/or other coverings or coatings.
  • the cladding 420, 520 may be selected such that it is easier to retain by solder than the shape memory alloy portion 430, 530 of the SMA element 266, 366, 416, 516.
  • the cladding is located at least at the ends of the SMA element 266, 366, 416, 516.
  • the cladding 420, 520 may be added by any number of techniques such as electroplating, vapor deposition, electrodeposition, printing, and/or another plating technique.
  • a first exemplary switch 602 that is actuated by an SMA element 618 includes a housing 610 (e.g. a cup) configured to hold portions of the SMA actuator 604.
  • the housing 610 includes electrical leads 608 for connecting the SMA element 618 to other circuit components (e.g. a monitoring circuit, a power circuit, a control circuit, etc.) (see, e.g. Figs. 17 and 18).
  • the SMA element 618 is held in place by a body 612.
  • body 612 includes a space 613 adapted to receive a spindle 616.
  • Spindle 616 is held such that it can rotate within space 613.
  • SMA element 618 is placed around body 612 such that barrel crimps 620 extend into spaces in body 612.
  • SMA element 618 is held by body 612 such that SMA element 618 is electrically coupled to leads 608 (Fig. 21A).
  • SMA element 618 is also placed over spindle 616.
  • SMA element 618 is arranged such that bent portion 619 of SMA element 618 is arranged around projections 633 in spindle 616.
  • Projections 633 include links 634 which serve as attachment points for springs 614.
  • SMA element 618 is actuated (e.g. may be heated by passing a current through SMA element 618 via leads 608 (Fig. 21A) in housing 610 (Fig. 21A)).
  • SMA element 618 may be configured to contract, causing bent portion 619 to straighten (although may not become completely straight). Straightening of bent portion 619 causes bent portion 619 to pull on projections 633 of spindle 616, thereby causing spindle 616 to rotate clockwise against the action of springs 614. See, e.g. Figs. 22A-22D.
  • springs 614 may act to bring spindle 616 and SMA element 618 back to their rest positions.
  • SMA element 618 When released from being actuated, SMA element 618 may exhibit a two-way memory effect such that the rest state (e.g. low temperature state) "memorized" by SMA element 618 (with or without the aid of springs 614) helps to bring SMA element 618 back to its rest state position (the springs 614 bringing spindle 616 back to its rest state position).
  • additional projections could be placed in spindle 616 on the opposite side of
  • SMA element 618 as projections 633 to allow SMA element's 618 transition to its rest state position to also bring spindle 616 back to its rest state position (with or without the aid of springs 614).
  • switch 602 also includes a body 622.
  • Body 622 includes a projection 624 that mates with a hole 636 (Fig. 21B) in spindle 616 (although it should be appreciated that body 622 and spindle 616 could be mated by any other means, including by making body 622 integral with spindle 616).
  • Body 622 includes a conductive strip 626.
  • body 622 is configured to be inserted in an insulative housing 628.
  • Housing 628 carries leads 630 configured to be connected to a circuit (e.g. leads 630 may be a portion of a relay connected to an antenna circuit, connected to an electric motor circuit, etc.).
  • Leads 630 include internal projections 640 that extend around the interior surface of housing 628.
  • Conductive strip 626 becomes in contact with both leads 630, thereby connecting leads 630 to each other (closing the circuit to which leads 630 are connected).
  • bent portion 619 (Fig. 21B) is shown as a double curved bend, the bent portion 619 may take any other shape capable of causing rotation including a single curve bend (see Fig. 24)
  • an SMA element 705 includes a bent portion 710 similar to bent portion 619 (Fig. 21B) of SMA element 618 (Fig. 21B).
  • SMA element 705 has a rest state 720 in which the actuator not actuated, an intermediate unactuated (transition) state 730 in which the actuator is not in its rest state but is not actuated, an initial actuated state 740 at which the actuator is first actuated, and an extended actuated state 750 in which the actuator is actuated at a point beyond the initial actuated state 740.
  • a second exemplary switch 802 that is actuated by an SMA element 818 includes a housing 810 (e.g. cup) configured to hold portions of the SMA actuator 804.
  • the housing 810 includes electrical leads 808 for connecting the SMA element 818 to other circuit components (e.g. a monitoring circuit, a power circuit, a control circuit, etc.) (see, e.g. Figs. 2 and 3).
  • the SMA element 818 is held in place by a body 812.
  • Body 812 has a connector
  • Body 822 (e.g. a space surrounded by projections configured to form a snap connection) configured to receive and/or hold a connector 852 of a body 822.
  • Body 822 also includes a lever arm portion 854 and an extension portion 853.
  • Extension portion 853 carries contacts
  • SMA element 818 is connected to body 812 such that bent portion
  • lever arm 819 sits snugly over lever arm 854 on a portion of lever arm 854 that is on an interior side
  • SMA element 818 As SMA element 818 starts to change shape (e.g. contract), SMA element 818 will pull on lever arm 854 (and/or its projection 855) which will cause lever arm 854 (and thus body 822) to rotate towards body 812 around a pivot formed by connector 852.
  • Spring 814 is positioned to rotate body 822 in the opposite direction as
  • SMA element 818 starts to relax.
  • Switch 802 also includes housing 828 which includes leads 830 that are connected to a circuit (e.g. an antenna circuit). As body 822 rotates forward, extension 853 rotates contacts 826,827 forward into contact with an interior portion of leads 830, thereby completing that portion of the circuit to which leads 830 are connected.
  • a circuit e.g. an antenna circuit
  • SMA element 818 may have a rest state, intermediate states, and actuated states in the same manner as described with respect to SMA element 618, above.
  • SMA elements 618,818 may be soldered to (and/or a portion connected to) one or more of housing 610,810, body 612,812, and/or leads 608,808.
  • an SMA element 918 is configured to contract when heated.
  • an SMA actuator 1004 includes an SMA element
  • SMA element 1018 that extends through a passage 1082 in a body 1016. Actuation of SMA element 1018 causes SMA element 1018 to expand. Expansion of SMA element 1018 causes body 1016 to move upwards, actuating actuator 1004. Ends 1090 of SMA element 1018 may be fixed to housing 1010, a circuit board (not shown), or some other member. [0171] Any other arrangements may be used. According to some embodiments, the actuator 604, 804, 904, 1004 may be powered to maintain an unactuated state and power may be removed to go to the actuated state.
  • SMA element 618, 818, 918, 1018 may be maintained in an intermediate position whereby application of power to the SMA element may cause the actuator to actuate a first system, while removal of the maintenance power may cause the actuator to actuate a second system.
  • any number of other systems may be actuated by a single actuator where the actuator can be maintained in a number of different states.
  • SMA actuator 252 may be used to actuate a switch 270 such as a relay.
  • the switch/relay 270 may be configured to control a system 268.
  • the system could be any type of system, such as a vehicle system (e.g. a land vehicle system, an air vehicle system, a water vehicle system, etc.).
  • system 268 comprises an antenna system for an airplane, such that SMA actuator 252 is configured to actuate a relay 270 that controls a circuit of antenna 268.
  • SMA actuator 252 may be designed to operate in various conditions in which systems 268 are mounted.
  • SMA actuator 252 may be configured to operate in ambient temperatures up to about 125 0 C (or higher) and/or may be configured to operate in temperatures as low as -55 0 C (or lower).
  • SMA actuator 252 may be configured to operate in environments having high vibration such as environments where random, sinusoidal, or other vibration may occur up to or greater than 30 G' s RMS or where high impulse type impacts or shock of lower, similar, or greater force than 30 G's may occur.
  • SMA actuator 252 may also be configured to operate in environments having high vibration such as environments of shock (e.g.
  • an SMA element includes a shape memory alloy core and a ferromagnetic cladding.
  • the shape memory alloy core is a rod formed from a Nitinol (NiTi) alloy.
  • the core has a diameter of about 0.004 inches and a length of about 2 inches.
  • the cladding is formed over the core from a Ni plating.
  • the cladding extends over essentially the entire core and has a thickness above the core of about 0.0005 inches such that the total diameter for the SMA element is about 0.005 inches.
  • an SMA element includes a shape memory alloy core and a ferromagnetic cladding.
  • the shape memory alloy core is a rod formed from a Nitinol alloy.
  • the core has a diameter of about 0.008 inches and a length of about 2 inches.
  • the cladding is formed over the core from a Ni alloy.
  • the cladding extends over essentially the entire core and has a thickness above the core of about 0.001 inches such that the total diameter for the SMA element is about 0.01 inches.
  • an SMA element includes a shape memory alloy core and a ferromagnetic cladding.
  • the shape memory alloy core is a rod formed from a Nitinol alloy.
  • the core has a diameter of about 0.01 inches and a length of about 2 inches.
  • the cladding is formed over the core from a Nickel plating.
  • the cladding extends over essentially the entire core and has a thickness above the core of about 100 microinches.
  • an SMA element includes a shape memory alloy core and a ferromagnetic cladding.
  • the shape memory alloy core is a foil formed from a Nitinol alloy.
  • the core has a thickness of about 0.004 inches, a width of about 0.02 inches, and a length of about 2 inches.
  • the cladding is formed over the core from Ni.
  • the cladding extends over essentially the entire core and has a thickness above the core of about 0.0005 inches such that the total thickness for the SMA element is about 0.005 inches.
  • an SMA element includes a shape memory alloy core and a ferromagnetic cladding.
  • the shape memory alloy core is a foil formed from a Nitinol
  • the foil has a thickness of about 0.003 inch, a width of about 0.2 inch, and a length of about 2 inches.
  • the cladding is formed over the core from a Nickel plating.
  • the core extends over essentially the entire core and has a thickness above the core of about 500 microinches.
  • an SMA element consists essentially of a shape memory alloy.
  • the shape memory alloy is a rod formed from a NiTi alloy.
  • the SMA element has a diameter of about 0.002 inches and a length of about 2 inches.
  • an SMA element consists essentially of a shape memory alloy.
  • the shape memory alloy is a rod formed from a NiTi alloy.
  • the SMA element has a diameter of about 0.004 inches and a length of about 2 inches.
  • an SMA element consists essentially of a shape memory alloy.
  • the shape memory alloy is a rod formed from a NiTi alloy.
  • the SMA element has a diameter of about 0.01 inches and a length of about 3 inches.
  • an SMA actuator is constructed as shown and described above in
  • the SMA actuator includes an SMA element as described above in Example 7.
  • a DC power signal of about 1.25 volts and 0.17 amps is provided to the SMA element.
  • the DC signal heats the SMA element but does not cause the SMA element to change shape.
  • a second DC power signal of about 0.7 volts and 0.01 amps is provided to the SMA element to actuate the SMA element.
  • the SMA element is actuated in about 50 ms from sending the second DC signal, and can be actuated for at least
  • an SMA actuator is constructed as discussed above in Example
  • the current of the first signal is adjusted based on the resistance measured in the SMA element circuit.
  • an SMA actuator is constructed as discussed above in Example
  • the actuator further includes an oscillator circuit configured to provide an RF signal to the SMA element.
  • the actuator also includes an OpAmp in series with the SMA element to measure impedance in the SMA element circuit. The first DC signal is adjusted based on the amount of impedance measured in the SMA element circuit.
  • an SMA actuator is constructed as discussed above in Example
  • the actuator additionally includes tick marks spaced at 1° intervals along the perimeter of the rotating body of the actuator.
  • An optical sensor is positioned to identify tick marks crossing the sensor and provide an output to a control circuit.
  • the control circuit is configured to count the tick marks to keep track of the degree of rotation of the rotating body.
  • the control circuit is further configured to control the extent of the first DC signal based on the degree of rotation of the rotating body.
  • an SMA actuator is constructed as shown and described above in Figs. 2 IA-C.
  • the SMA actuator includes an SMA element as described above in
  • a DC power signal of about 1.25 volts and 0.17 amps is provided to the SMA element along with a 0.2 volt, 0.01 amp RF signal modulated at a frequency of about 10 MHz.
  • the DC and RF signals heat the SMA element but do not cause the SMA actuator to actuate.
  • An RF Detector is provided in series with the SMA element to measure the impedance of the SMA element to the RF signal.
  • the DC signal is adjusted based on the measured impedance.
  • a second RF power signal of about 5 volts and 2 amps is provided to the SMA element to actuate the SMA element (e.g. the first RF signal is increased).
  • the SMA element is actuated in about 2-5 ms from sending the second RF signal, and can be actuated for at least 100,000 cycles.
  • an SMA actuator is constructed as disclosed in Example 14.
  • the SMA actuator is further configured to adjust the second RF power signal based on the measured impedance.
  • an SMA actuator is constructed as described above in Example
  • the SMA actuator is able to operate between at least the temperatures of -55 0 C and
  • the SMA actuator can also withstand the effects of vibration of the environment in which it is located (e.g. can withstand 30 G's RMS).
  • the SMA actuator can also withstand other environmental effects such as high impulse type impacts or shock of lower, similar, or greater force than 30 G's that may occur.
  • a relay is constructed from an SMA element as described above in Examples 10 and 12.
  • the relay is mounted in an airplane and is used to perform impedance matching and tuning functions of the RF communication and antenna system for optimum signal transfer.
  • FIGS. 26 through 36 illustrate exemplary electrical switching devices, which employ actuator mechanisms formed of a shape memory alloy (SMA) in accordance with exemplary embodiments of the present invention.
  • SMA shape memory alloy
  • Each electrical switching device 1000 illustrated comprises a housing 1002 having one or more non-actuated electrical contacts 1004 and 1006 mounted in the housing 1002.
  • An actuator assembly 1008 is supported within the housing 1002.
  • the actuator assembly is supported within the housing 1002.
  • 1008 includes a movable contact 1010 for engaging the non-actuated electrical contacts
  • the actuator assembly 1008 moves the movable contact 1010 between an actuated position, wherein the movable contact 1010 engages the non-actuated electrical contacts 1004 and 1006 and a non-actuated position, wherein the movable contact 1010 is disengaged from the contacts 1004 and 1006.
  • the non-actuated contacts 1004 and 1006 and the movable contact 1010 are formed of a conductive material such as copper, rhodium, a tungsten/molybdenum alloy, or the like.
  • the actuator assembly 1008 includes an actuator 1012 formed of a of a shape memory alloy (SMA) which changes shape upon the application of an electric current (e.g., when heated by the application of an electric current).
  • SMA shape memory alloy
  • the application of an electrical current to the actuator 1012 causes the actuator 1012 to move the movable contact 1010 to either engage or disengage the non-actuated electrical contacts 1004 and 1006 so that the flow of an electric current through the contacts 1004 and 1006 is either allowed or inhibited.
  • the actuator 1012 is formed of a nickel-titanium alloy such as Nitinol.
  • shape memory alloy SMA
  • shape memory alloy may include, but are not necessarily limited to, copper-aluminum-nickel alloys, copper-zinc-aluminum alloys, iron-manganese-silicon alloys, and the like.
  • shape memory alloys SMA
  • the actuator may employ a shape memory alloy (SMA) exhibiting a one-way shape memory effect.
  • the actuator 1012 upon being heated by the application of an electric current, acquires a predetermined shape, geometry or length without the application of an external force.
  • a return mechanism may be provided to return the actuator to its original position prior to heating.
  • the return mechanism may be mechanical (e.g., spring 1026), hydraulic, pneumatic, or the like.
  • the actuator 1012 may employ a shape memory alloy (SMA) exhibiting a two-way shape memory effect, wherein the actuator 1012 acquires two different shapes: one a low temperature shape when no electrical current is applied, and the other a high temperature shape acquired upon application of an electrical current.
  • SMA shape memory alloy
  • FIGS. 26, 27 and 28 illustrate a vacuum relay electrical switching device 1000 having a pivoting actuator assembly 1008 in accordance with an exemplary embodiment of the present invention.
  • the electrical switching device 1000 includes a vacuum tube housing 1002 having a hollow metal case 1014, a tubular insulator 1016 formed of an electrically insulating material such as glass, a ceramic, or the like, coupled to the case 1014, and a cap 1018 coupled to the insulator 1016 via a braze joint, or the like.
  • the volume within the vacuum tube housing 1002 (e.g., within cylindrical volume of the insulator 1016) is at least partially evacuated to form a vacuum which functions as a dielectric.
  • the volume within the vacuum tube housing 1002 may be filled with a gas such as sulfur hexafluoride (SF6), air, or the like.
  • SF6 sulfur hexafluoride
  • a first non- actuated contact 1004 is supported in the insulator 1016 of the housing 1002 near the middle of the insulator 1016.
  • a second non-actuated contact 1006 is provided by the cap 1018 of the insulator 1016.
  • Tabs 1020 and 1022 couple the non-actuated contacts 1004 and 1006 to external circuits.
  • the actuator assembly 1008 includes a flapper or diaphragm 1024 supported in the case 1014 of the housing 1002 for supporting in the movable contact 1010.
  • a spring 1026 (a coil spring is shown) extends between the bottom surface of the flapper 1024 and the internal surface of the bottom of the case 1014.
  • the actuator 1012 comprises a wire 1028 formed of shape memory alloy (SMA) material extending between the bottom surface of the flapper 1024 and the internal surface of the bottom of the case 1014 within the spring 1026.
  • the wire 1028 is electrically coupled to pins 1030 and 1032 mounted to the bottom of the case 1014 and extending from the outer surface of the bottom of the case 1014 so that an electric current may be applied to the wire 1028.
  • SMA shape memory alloy
  • the actuator assembly 1008 is shown in the non-actuated state in FIG. 27.
  • the wire 1028 contracts and shortens, pivoting the flapper 1024 downward and compressing the spring 1026.
  • the flapper 1024 in turn pivots the movable contact 1010 so that the movable contact 1010 engages (makes physical contact with) the first and second non-actuated electrical contacts 1004 and 1006 completing a circuit between the first and second contacts 1004 and 1006 so that a second electric current may flow between the non-actuated contacts 1004 and 1006 through the movable contact 1010.
  • FIGS. 29, 30 and 31 illustrate a second vacuum relay electrical switching device 1000 having a rotating actuator assembly 1008 in accordance with an exemplary embodiment of the present invention.
  • the electrical switching device 1000 again includes a vacuum tube housing 1002 having a case 1014, a tubular insulator 1016 formed of an electrically insulating material such as glass, a ceramic, or the like, coupled to the case 1014, and a cap 1018 coupled to the insulator 1016.
  • the volume within the vacuum tube housing 1002 may be at least partially evacuated to form a vacuum which functions as a dielectric.
  • the volume within the vacuum tube housing may be filled with a gas such as sulfur hexafluoride (SF6), air, or the like.
  • SF6 sulfur hexafluoride
  • a first non-actuated contact 1004 is provided by the cap 1018 of the insulator 1016, while a second non-actuated contact 1006 is supported in the insulator 1016 of the housing 1002 near the middle of the insulator 1016.
  • Tabs 1020 and 1022 couple the non-actuated contacts 1004 and 1006 to external circuits.
  • the actuator 1012 comprises a coil or spiral 1034 formed of shape memory alloy (SMA) material.
  • the movable contact 1010 comprises a rotor 1036 coupled to the coil 1034 via a shaft 1038 which wipes non-actuated contacts 1004 and 1006 when rotated.
  • the coil 1036 is electrically coupled to pins 1030 and 1032 mounted to the bottom of the case 1014 and extending from the outer surface of the bottom of the case 1014.
  • the coil 1034 contracts, tightening, and rotating the shaft 1038 which in turn rotates the rotor 1036 (e.g., in a clockwise direction) so that the rotor 1036 engages the first and second non- actuated electrical contacts 1004 and 1006 completing a circuit between the contacts 1004 and 1006 so that a second electric current may flow between the non-actuated contacts 1004 and 1006 through the movable contact 1010.
  • the contraction of the coil 1034 ceases so that the coil 1034 uncoils rotating the shaft 1036 in the direction opposite the direction the shaft 1038 was rotated when the electric current was applied (e.g., the counterclockwise direction).
  • the shaft 1038 in turn rotates the rotor 1036 to the non actuated position shown in FIG. 31 so that the rotor 1036 no longer engages the first and second non-actuated electrical contacts 1004 and 1006 opening the circuit so that flow of the second electric current between the contacts 1004 and 1006 is inhibited.
  • the shape memory alloy (SMA) material from which the coil 1034 is fabricated may be selected to achieve the specific response required by the application in which the vacuum relay electrical switching device 1000 is used.
  • FIGS. 32, 33 and 34 illustrate a third vacuum relay electrical switching device 1000 having a rotating actuator assembly 1008 in accordance with an alternative exemplary embodiment of the present invention.
  • the electrical switching device 1000 includes a vacuum tube housing 1002 having a case or base 1014 and an insulator 1016 formed of an insulating material such as glass, a ceramic, or the like, coupled to the case 1014.
  • the volume within the vacuum tube housing 1008 (e.g., within insulator 1016) may be at least partially evacuated to form a vacuum which functions as a dielectric.
  • the volume within the vacuum tube housing may be filled with a gas such as sulfur hexafluoride (SF6), air, or the like.
  • SF6 sulfur hexafluoride
  • First and second non-actuated contacts 104 and 1006 extend through the top of the insulator 1016 of the housing 1002 and along the sides of the insulator 1016.
  • the actuator 1012 comprises shaped block 1040 formed of shape memory alloy (SMA) material having a generally funnel shaped cross-section.
  • the movable contact 1012 comprises a bar 1042 coupled to the shaped block 1040 via a shaft 1044 so that the bar 1042 engages or wipes the non-actuated contacts 1004 and 1006 when rotated.
  • the shaped block 1040 is electrically coupled to pins 1030 and 1032 extending from the outer surface of the bottom of the case 1014 so that an electric current may be applied to the block 1040.
  • the block 1040 twists, rotating the shaft 1044 which in turn rotates the bar 1042 (e.g., in a clockwise direction) so that it engages the first and second electrical contacts 1004 and 1006, completing a circuit between the first and second contacts 1004 and 1006 allowing a second electric current to flow through the contacts 1004 and 1006.
  • the twist of the block ceases so that the block 1040 untwists, rotating the shaft 1044 in the opposite (e.g., counterclockwise) direction.
  • the shaft 1044 in turn rotates the bar 1042 to the non- actuated position shown in FIG. 34.
  • the bar 1042 no longer engages the first and second non-actuated electrical contacts 1004 and 1006 opening the circuit so that flow of the second electric current between the contacts 1004 and 1006 is inhibited.
  • shape memory alloy (SMA) material from which the shaped block 1040 of the present embodiment is fabricated may be selected to achieve the specific response required by the application in which the vacuum relay electrical switching device 1000 is used.
  • the shaped block 1040 may be formed of Nitinol exhibiting a two-way memory effect, and configured to contract approximately 7% when an electrical current impulse of 3 V at 10mA (nominal) is applied thereby causing the block 1040 to twist due to its shape.
  • the shaped block 1040 may alternatively be formed of other shape memory alloy (SMA) materials, including shape memory alloy (SMA) materials exhibiting a one-way shape memory effect, or the like, without departing from the scope and intent of the present invention.
  • SMA shape memory alloy
  • FIGS. 35 and 36 illustrate an electrical switching device 1000 having an actuator assembly 1012 including a filament actuator in accordance with a fourth exemplary embodiment of the present invention.
  • the electrical switching device 1000 includes a vacuum tube housing 1002 having a hollow metal case 1014 and an insulator 1016 formed of an insulating material such as glass, a ceramic, or the like, coupled to the case 1014.
  • the volume within the vacuum tube housing 1008 (e.g., within insulator 1016) is at least partially evacuated to form a vacuum which functions as a dielectric.
  • the volume within the vacuum tube housing may be filled with a gas such as sulfur hexafluoride (SF6), air, or the like.
  • Non-actuated electrical contacts 1004 and 1006 are supported in the insulator 1016 of the housing 1002.
  • the actuator 1012 comprises a filament 1046 of shape memory alloy (SMA) material having two control leads or pins 1030 and 1032 extending from the outer surface of the bottom of the case 1014. As shown, all but a section 1048 of the filament 1046 is held (e.g., encased within a sleeve 1050, or the like) which prevents movement of the filament 1046.
  • the section 1050 not held within the sleeve is surrounded by movable contact 1010, which is allowed to slide between a first position, wherein the movable contact 1010 does not engage the non-actuated contacts 1004 and 1006 and a second position wherein the movable contact 1010 engages the non-actuated electrical contacts 1004 and 1006.
  • the filament 1046 contracts allowing the movable contact 1010 to disengage the non-actuated contacts.
  • the contraction of the filament 1046 ceases so that the filament 1046 is allowed to lengthen.
  • the exposed section 1050 of filament 1046 bows outward, as shown in FIG. 36, so that the movable contact 1010 engages the non-actuated electrical contacts 1004 and 1006 completing a circuit between the contacts 1004 and 1006 as shown, or alternately, if the filament 1046 is instead allowed to bow away from the contacts 1004 and 1006, opening the circuit so that flow of the second electric current between the non-actuated electrical contacts 1004 and 1006 is inhibited.
  • the diameter (gauge) of the filament 1046 and the shape memory alloy (SMA) material from which the filament 1046 is fabricated may be selected to achieve the specific response required by the application in which the vacuum relay electrical switching device 1000 is used.
  • the filament 1046 may exhibit either one-way or two-way shape memory effect. If a filament 1046 exhibiting oneway shape memory effect is employed, a return mechanism such as a mechanical device (e.g., a spring assembly), a hydraulic device, a pneumatic device, or the like, may be utilized to bias the movable contact 1010 to either the opened (non-engaged) or closed (engaged) positions.
  • the electrical switching devices 1000 illustrated may comprise vacuum tube electrical devices such as vacuum relays, switches, resettable fuses, or the like which employ a vacuum tube housing 1002.
  • vacuum tube electrical devices such as vacuum relays, switches, resettable fuses, or the like which employ a vacuum tube housing 1002.
  • electrical switching devices 1000 in accordance with the present invention need not be limited to such embodiments.
  • single pole, single throw (SPST) relays are shown for purposes of illustration, however it is contemplated that double pole and/or double throw relays (e.g., SPDT, DPDT, etc.) or even multiple pole, multiple throw relays may also be implemented without departing from the scope and intent of the present invention, for example, by modifying the configuration of the contacts being used.

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Abstract

L'invention porte sur un actionneur (252) comprenant un élément en alliage à mémoire de forme (266) configuré pour changer de forme de sorte qu'un changement de forme provoque un actionnement de l'actionneur. L'actionneur (252) comprend aussi un circuit de puissance (262) configuré pour fournir un signal de puissance qui amène l'alliage à mémoire de forme à changer de forme. L'actionneur (252) comprend aussi un circuit (264) configuré pour commander une source d'alimentation afin d'appliquer un second signal de puissance qui amène l'alliage à mémoire de forme à être dans un état pré-actionné.
PCT/US2008/073330 2007-09-24 2008-08-15 Alliage à mémoire de forme et actionneur WO2009042306A1 (fr)

Applications Claiming Priority (6)

Application Number Priority Date Filing Date Title
US11/903,666 2007-09-24
US11/903,666 US9136078B1 (en) 2007-09-24 2007-09-24 Stimulus for achieving high performance when switching SMA devices
US11/963,741 2007-12-21
US11/963,738 2007-12-21
US11/963,738 US8051656B1 (en) 2007-12-21 2007-12-21 Shape-memory alloy actuator
US11/963,741 US8220259B1 (en) 2007-12-21 2007-12-21 Shape-memory alloy actuator

Publications (1)

Publication Number Publication Date
WO2009042306A1 true WO2009042306A1 (fr) 2009-04-02

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US2008/073330 WO2009042306A1 (fr) 2007-09-24 2008-08-15 Alliage à mémoire de forme et actionneur

Country Status (1)

Country Link
WO (1) WO2009042306A1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8051656B1 (en) 2007-12-21 2011-11-08 Rockwell Collins, Inc. Shape-memory alloy actuator
WO2019079740A1 (fr) * 2017-10-20 2019-04-25 Georgia Tech Research Corporation Géométrie de contact électrique pour appareillage de commutation
WO2023046290A1 (fr) * 2021-09-24 2023-03-30 Siemens Aktiengesellschaft Dispositif de déclenchement d'interrupteur électrique, dispositif de déclenchement de tension et dispositif de déclenchement sous-tension comportant un tel dispositif, et unité de vente comportant un tel dispositif

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2672110B2 (ja) * 1988-04-13 1997-11-05 オリンパス光学工業株式会社 形状記憶アクチュエータ
US6516146B1 (en) * 1999-11-16 2003-02-04 Minolta Co., Ltd. Actuator using shape memory alloy and method for controlling the same
WO2003095798A1 (fr) * 2002-05-06 2003-11-20 Nanomuscle, Inc. Actionneurs sma hautement integres a course elevee
US6981374B2 (en) * 2001-02-22 2006-01-03 Alfmeier Prazision Ag SMA actuator with improved temperature control
US7256518B2 (en) * 2000-05-08 2007-08-14 Gummin Mark A Shape memory alloy actuators

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2672110B2 (ja) * 1988-04-13 1997-11-05 オリンパス光学工業株式会社 形状記憶アクチュエータ
US6516146B1 (en) * 1999-11-16 2003-02-04 Minolta Co., Ltd. Actuator using shape memory alloy and method for controlling the same
US7256518B2 (en) * 2000-05-08 2007-08-14 Gummin Mark A Shape memory alloy actuators
US6981374B2 (en) * 2001-02-22 2006-01-03 Alfmeier Prazision Ag SMA actuator with improved temperature control
WO2003095798A1 (fr) * 2002-05-06 2003-11-20 Nanomuscle, Inc. Actionneurs sma hautement integres a course elevee

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8051656B1 (en) 2007-12-21 2011-11-08 Rockwell Collins, Inc. Shape-memory alloy actuator
WO2019079740A1 (fr) * 2017-10-20 2019-04-25 Georgia Tech Research Corporation Géométrie de contact électrique pour appareillage de commutation
US11424084B2 (en) 2017-10-20 2022-08-23 Georgia Tech Research Corporation Electrical contact geometry for switchgear
WO2023046290A1 (fr) * 2021-09-24 2023-03-30 Siemens Aktiengesellschaft Dispositif de déclenchement d'interrupteur électrique, dispositif de déclenchement de tension et dispositif de déclenchement sous-tension comportant un tel dispositif, et unité de vente comportant un tel dispositif

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