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WO2017144873A1 - Dispositif d'accord rf, actionneur et procédé - Google Patents

Dispositif d'accord rf, actionneur et procédé Download PDF

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Publication number
WO2017144873A1
WO2017144873A1 PCT/GB2017/050454 GB2017050454W WO2017144873A1 WO 2017144873 A1 WO2017144873 A1 WO 2017144873A1 GB 2017050454 W GB2017050454 W GB 2017050454W WO 2017144873 A1 WO2017144873 A1 WO 2017144873A1
Authority
WO
WIPO (PCT)
Prior art keywords
actuator
wire
sma
cavity
tuning
Prior art date
Application number
PCT/GB2017/050454
Other languages
English (en)
Inventor
Anthony Hooley
Original Assignee
Anthony Hooley
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
Application filed by Anthony Hooley filed Critical Anthony Hooley
Publication of WO2017144873A1 publication Critical patent/WO2017144873A1/fr

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Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03J—TUNING RESONANT CIRCUITS; SELECTING RESONANT CIRCUITS
    • H03J1/00—Details of adjusting, driving, indicating, or mechanical control arrangements for resonant circuits in general
    • H03J1/06—Driving or adjusting arrangements; combined with other driving or adjusting arrangements, e.g. of gain control
    • H03J1/10—Rope drive; Chain drive
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03J—TUNING RESONANT CIRCUITS; SELECTING RESONANT CIRCUITS
    • H03J3/00—Continuous tuning
    • H03J3/20—Continuous tuning of single resonant circuit by varying inductance only or capacitance only
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
    • H01P7/00—Resonators of the waveguide type
    • H01P7/06—Cavity resonators
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03B—GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS
    • H03B2201/00—Aspects of oscillators relating to varying the frequency of the oscillations
    • H03B2201/01—Varying the frequency of the oscillations by manual means
    • H03B2201/014—Varying the frequency of the oscillations by manual means the means being associated with an element comprising distributed inductances and capacitances
    • H03B2201/015—Varying the frequency of the oscillations by manual means the means being associated with an element comprising distributed inductances and capacitances the element being a cavity
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03B—GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS
    • H03B2201/00—Aspects of oscillators relating to varying the frequency of the oscillations
    • H03B2201/02—Varying the frequency of the oscillations by electronic means
    • H03B2201/0225—Varying the frequency of the oscillations by electronic means the means being associated with an element comprising distributed inductances and capacitances
    • H03B2201/0233—Varying the frequency of the oscillations by electronic means the means being associated with an element comprising distributed inductances and capacitances the element being a cavity

Definitions

  • the invention relates to an RF (radio frequency) tuning device, an actuator for use in an RF tuning device, and associated methods.
  • the actuator is suitable for accurate positioning over small displacements, and may find application in tuning RF devices such as RF cavities or RF antennas.
  • Shape Memory Alloy is a well known actuator material and its most common form is a wire made of NiTi (Nickel-Titanium) alloy in roughly 50:50 proportions and possibly with other trace additives.
  • NiTi wire (after suitable treatment during manufacture) has the unusual property of contracting by between ⁇ 3% to ⁇ 10% when heated through a narrow temperature range (e.g. say between ⁇ 80C and ⁇ 1 10C) the actual temperature range being a function both of the precise alloy composition, and the stress in the wire.
  • arbitrarily fast activation (contraction) can be achieved by applying sufficient heating power, with care taken not to overheat the wire.
  • the wire may be heated in any practical way but the most useful and simplest is usually Joule-heating by the application of an electric current through the wire.
  • the chosen wire thickness can natural- convection-cool adequately quickly then a practical design has been achieved. If too slow, then splitting the wire into several parallel thinner strands will often achieve suitably fast operation. If not, then some form of active cooling is required which might be for example forced-air- or water- cooling.
  • the SMA bowstring actuator is known in the art, and is formed by attaching both ends of an SMA-wire to a nominally fixed base or frame, the ends being slightly closer together than the length of the wire so that there is a bit of slack. The load is then attached to the mid-point of the wire, and the actuation force is in the direction orthogonal to the line through the wire ends.
  • a spring may be used for this purpose.
  • a second SMA actuator may be used, and this second actuator may also be a bowstring actuator.
  • This configuration comprising two opposing bowstring actuators is hereby referred to as a double bowstring actuator, and the form is known in the art (see e.g. US2012/0104292 Active Drain Plug for High Voltage Battery Applications, Kollar, C.A. et al).
  • the control of the actuator is achieved by heating and cooling the SMA wire.
  • Position-feedback is thus essential in most if not all precision positioner applications.
  • One good proxy for SMA wire-length, and thus for actuator position, is SMA wire-resistance.
  • a simple measurement of the electrical resistance of the SMA wire of the actuator can be used to derive a good estimate of the wire-length, and thus the output position of the actuator.
  • This technique which is known in the art, provides reasonable precision position-estimation without the addition of a separate position-sensor, and is thus cheap and simple to implement, as well as being compact. Summary of Invention
  • the invention provides an RF-cavity tuning device, an RF tuning device, a method for tuning an RF cavity, a method for RF tuning, and a method for developing an actuator as defined in the appended independent claims, to which reference should now be made.
  • Tuning an RF cavity requires rapid, accurate positional control of a small, low-mass tuning pin or similar apparatus.
  • the same requirements apply to the tuning of other RF devices such as RF antennas, and the description herein relating to RF cavities therefore also applies to such devices.
  • SMA actuators Shape memory alloy (SMA) actuators are known, as described above, but the skilled person's conventional wisdom is that SMA actuators are only suitable for applying relatively high forces in a relatively poorly controlled way. Thus, for example, SMA actuators are known to be used for "on-off" switching purposes, or for opening and closing valves or taps. However, the inventor has appreciated that despite the apparently poor matching of the requirements for tuning an RF cavity and the actuator properties of an SMA actuator, in fact a carefully-designed SMA actuator can, surprisingly, be effectively used for tuning an RF cavity.
  • the SMA-wire of an SMA-wire actuator When the temperature Top of the SMA-wire of an SMA-wire actuator is increased between the temperature limits Tmin to Tmax (both specific to the particular formulation of the SMA-wire used, but typically ⁇ 80C ⁇ Tmin ⁇ Tmax ⁇ 1 10C, or for some types of SMA wire even ⁇ 140C or ⁇ 160C), the SMA-wire shortens and is able to apply a force to a mechanical load.
  • Tmin to Tmax both specific to the particular formulation of the SMA-wire used, but typically ⁇ 80C ⁇ Tmin ⁇ Tmax ⁇ 1 10C, or for some types of SMA wire even ⁇ 140C or ⁇ 160C
  • Top of the SMA-wire When Top of the SMA-wire is decreased between Tmin and Tmax, the SMA-wire may lengthen but in general it will only do so if an external tension force is applied to it.
  • At least two separate force producing components are required: one of these is the SMA-wire of the actuator, and the other can be any convenient force producing device, including but not exhaustively, a gravity-pulled weight, a mechanical spring that has previously been stretched by the shortening of the SMA-wire, or a second SMA-wire actuator separately controlled from the first, such that the second SMA-wire actuator has its wire temperature increased between the limits Tmin and Tmax, when the first SMA- wire's wire-temperature is being decreased.
  • This part of the cycle of the first SMA- actuator is called the "return-stroke".
  • Tmax may vary over a wide range and may be as high as 140C or even 160C or more.
  • the present invention seeks to address some or all of the following problems: first, SMA wire is commercially available in only a relatively few standard diameters (and thus a relatively few maximum-pulling-force values); secondly, if the displacement required from the actuator is sufficiently large, and the overall compactness required of the actuator, are such that a standard straight-wire actuator will not fit within the design envelope, then some sort of mechanical leverage system is needed to achieve the specified displacement; thirdly, if the operating power available is sufficiently small that the use of a thicker wire to provide more initial force prior to the lever arrangement (which increases mechanical displacement but reduces
  • cold length means the length (of an SMA component) when the SMA material is completely un-actuated, i.e. for NiTi when all the material of the SMA component is in the Martensite state, and when the stress on the material is at least half the maximum safe working stress, and preferably for NiTi around 300MPa, to ensure that the SMA component is at its full "natural" length.
  • a first SMA wire, Wirel of cold length 2Lc, may be rigidly mechanically mounted to a fixed base structure (Base) at both ends of Wirel , such that the two wire ends are a distance 2Y apart, with 2Y ⁇ 2Lc, or equivalently, Y ⁇ Lc.
  • the two mechanical mounts also incorporate electrical connections to the ends of Wirel , these being denoted as terminals T1 1 and T12.
  • the electrical portions of T1 1 and T12 are electrically insulated from each other.
  • the Base may be electrically conductive, e.g. metal; any other suitable mechanical and electrical arrangement that achieves the same ends as may be devised by those skilled in the art may be substituted without loss of generalization and is included herein.
  • the terminals T1 1 and T12 are metal e.g. phosphor-bronze components mechanically crimped to the SMA wire to provide good low-resistance electrical connection and strong mechanical connection without damage to the SMA wire, insulatedly mounted to the Base.
  • a second SMA wire, Wire2, of cold length 2Lc, is similarly (to Wirel ) mechanically and electrically mounted to the Base at both ends of Wire2, with terminals denoted as T21 and T22, such that the two ends of Wire2 are a distance 2Y apart, with Y ⁇ Lc as before.
  • T21 to T22 distance is the same as the T1 1 to T12 distance. In fact these separations could be quite different in size. Similarly, it may be desirable or convenient for the cold lengths of the two wires to be the same, but as the skilled person would understand, these lengths could be different, whether or not the separations between the mechanical mounts for the wires are the same or different.
  • the four terminals may be arranged such that a line through T1 1 and T12 is parallel to a line through T21 and T22, and also so that a line through T1 1 and T21 is parallel to a line through T12 and T22. In that case, the four terminals are positioned at the corners of a rectangle. As already noted the lengths of each of one pair of parallel sides of the rectangle are of length 2Y. Let the length of each of the other two parallel sides of the rectangle be 2Z. When Wirel is heated to its maximum actuated temperature Tmax then Wirel contracts to or near to its minimum length 2Lh ⁇ 2Lc. A further constraint on the dimensions is that 2Y ⁇ 2 Lh, or equivalently Y ⁇ Lh.
  • a control system capable of precision measurement of the resistance of at least one of the SMA wires, and preferably of both wires, and this control system continually or continuously estimates the length of the at least one wire from the resistance measurements whereupon using the known geometry of the actuator and preferably a measurement of the present ambient temperature around the actuator, the controller calculates the output position of the actuator and also controls the heating current in each wire to continuously maintain the output position of the actuator at any desired position or progressive sequence of positions within the stroke range of the actuator, as commanded by input signals to the controller.
  • the midpoints of Wirel and of Wire2 are mechanically linked by a Link which is electrically and thermally insulating, but mechanically stiff.
  • a Link which is electrically and thermally insulating, but mechanically stiff.
  • B 2 Lh 2 -Y 2 ;
  • a 2 Lc 2 -Y 2 ;
  • this actuator configuration which can be seen in a preferred embodiment to be comprised of a coupled symmetrical pair of opposing bowstring actuators, is capable of moving the Link between two limit positions, in either direction (along the line of the Link, or the line of motion of the Link), and obviates the need for a return spring for reverse actuation, each of the two bowstring actuators acting as the reverse mechanism for the other.
  • the mechanical displacement output achieved i.e. the movement of the Link, which preferably is the mechanical output element of the actuator
  • the mechanical displacement output achieved may be tailored to the required actuator specification and in particular can be greater than the
  • G L/sqrt(L 2 -Y 2 )
  • G leverage or mechanical gain
  • sqrt square root
  • L the SMA-wire length at angle c to the dimension Y which in turn is orthogonal to actuation direction.
  • the gain G When Y is ⁇ 0 the gain G ⁇ 1 .0 and the configuration is more or less equivalent to a straight-wire actuator. When Y ⁇ L the gain G becomes close to infinite. In practice a wide range of useful gains, 1 ⁇ G ⁇ 10 can be achieved. Of course when G is high the mechanical force output will be appropriately reduced by a factor ⁇ 1 /G times that of the SMA-wire alone. In practice, the maximum mechanical output force Fmax oi the actuator is given by
  • Fmax 2Fwmax*Sin( c ); where Fwmax is the maximum allowable tension in the SMA-wire, and as before c is the angle between the SMA-wire direction and the direction orthogonal to the movement of the Link.
  • G will be large only when L is close to Y in length, in which case angle c is quite close to Odeg, and the force output will be a small fraction of the wire's inherent pulling capability.
  • the mechanical gain G is not a constant but varies slightly with actuator output stroke, since L varies with the temperature of the SMA-wire. This is a small effect and may usually be neglected.
  • a pair of similar or identical bowstring SMA-wire actuators are mechanically coupled, preferably by a Link, at their wire-centres so as to act in opposition to each other. It will be apparent to those skilled in the art that a pair of dissimilar bowstring SMA- wire actuators mechanically coupled at or near their wire-centres so as to act in opposition to each other will also function perfectly well, but are merely less convenient to analyse and control.
  • the two bowstring actuators are arranged to lie in the same plane, although useful configurations are possible where this is not the case, and such configurations are included herein.
  • the mechanical coupling is thermally insulating, and preferably the mechanical coupling is electrically insulating.
  • the two bowstring actuators are arranged parallel to each other.
  • the two bowstring actuators are arranged so that their actuation directions lie along the same line.
  • the two bowstring actuators have similar or identical dimensions to each other.
  • the two bowstring actuators have mirror symmetry.
  • the two bowstring actuators are controlled in such a manner that when one SMA-wire is fully heated to maximum working temperature Tmax and thus actuated (contracted), the other wire is minimally heated and capable of reaching full or near to full cold length at low stress, and vice versa.
  • Tmax maximum working temperature
  • heating of the other wire is controlled such as to maintain the stress in both wires safely below their maximum safe working stress.
  • the actuator controller is arranged to provide controlled heating to one or the other (or both) SMA-wires so as to allow, zero, partial or full actuation in either direction.
  • a control system may be provided capable of measuring the position of the actuator output (i.e. that part of the actuator connected to its load, to be moved by the actuator) by the use of suitable position sensor means.
  • the position sensor means are implemented by electrical resistance measurement of one or more of the SMA-wires of the actuator embodiments, and from the measurement(s) of resistance said control system using a first algorithm estimates the instantaneous length(s) of the SMA-wire(s), and from these length estimates together with knowledge of the specific actuator mechanical configuration and geometry of the controller is capable of estimating the output position of the actuator and thus is able to accurately position the external load mechanically driven by the actuator.
  • the controller continually or continuously uses the position-sensor data to estimate the position of the actuator output.
  • the controller uses temperature sensor means to sense the ambient temperature around the actuator and its wires, and in a more preferred embodiment temperature sensor means are implemented by one or more of the SMA-wires of the actuator and the controller uses a second algorithm to estimate the ambient temperature from internal parameters and electrical measurements of one or more of the SMA wires.
  • the controller in all embodiments described controls the electrical heating current to the one or more SMA wires.
  • the controller continually or continuously maintains the output position of the actuator at precise position or positions within the stroke range of the actuator, which said positions may be commanded from time to time by input signals to the controller from an external system.
  • a related aspect of the present invention may advantageously provide a design method or methodology for the design of a precision continuously positioning SMA- wire actuator of the present invention which given an actuator-specification determines the dimensions and geometry of the actuator, including the wire size, said method being described in detail below, complete with relevant design equations.
  • an SMA-wire actuator is connected via a mechanical link to an RF tuning pin causing the tuning pin to move in and out of an RF cavity so as to adjust the electromagnetic tuning of the cavity.
  • the mechanical link is electrically insulated.
  • the SMA-wire actuator is capable of precision continuous positioning to any point throughout its stroke.
  • the SMA-wire actuator comprises a straight section of SMA-wire connected in series to a mechanical spring which provides the return force for the return-stroke of the SMA-wire actuator cycle.
  • the SMA-wire actuator comprises two separate straight-wire SMA actuators mechanically connected in series, each actuator capable of providing the return force for the other during the other's return-stroke of its SMA-wire actuator cycle.
  • the two separate straight-wire actuators have similar or identical dimensions, and the wires of each are preferably aligned along the same line or direction.
  • the SMA-wire actuator is a bowstring-actuator with a mechanical spring to provide return force for the return stroke of the SMA-wire bowstring-actuator cycle.
  • the SMA- wire actuator comprises a pair of opposed bowstring-actuators mechanically connected in opposition, each bowstring-actuator acting to produce the return force for the other bowstring-actuator's return stroke of that other bowstring-actuator's cycle.
  • the two bowstring actuators have similar or identical dimensions.
  • the two bowstring actuators are positioned with their actuation directions lying along the same direction line.
  • a first preferred mechanical configuration is the IOB (Inwards Opposed
  • a more compact preferred mechanical configuration is the OOB (Outwards Opposed Bowstrings) configuration.
  • a most compact preferred mechanical configuration is the AOB (Alternate Overlapping Bowstrings)
  • a control system may be provided capable of measuring the position of the load by the use of suitable position sensing.
  • the position sensing is implemented by electrical resistance measurement of one or more of the SMA-wires of the actuator
  • an RF antenna tuning device is comprised of any one or more of the SMA- actuators herein described connected via a mechanical link to a moveable tuning element such that the element moves relative to the other components of the antenna tuning device, in so doing changing the optimum frequency of the antenna tuner.
  • Fig.1 shows a plan view schematically illustrating an actuator embodying the present invention.
  • Fig.2 shows the same plan view of the actuator as Fig.1 but in the oppositely actuated state.
  • Fig. 3 is to be interpreted as a geometrical layout representation of the same actuator as shown in Figs.1 and 2.
  • Fig.4 illustrates an alternative geometry of an actuator embodying the present invention.
  • Fig.5 illustrates a most compact geometry of an actuator embodying the present invention.
  • Fig.6 shows a schematic plan view of an example of a physical embodiment of the present invention.
  • Fig.7 is a perspective view of a complete double bowstring actuator with an RF tuning pin attached to its output port, according to an embodiment of the invention.
  • Fig.8 illustrates the attachment of the actuator in Fig.7 to an RF tuning cavity.
  • Fig.9 is a close-up of cut-away portion of the RF cavity of Fig.8 and the actuator and tuning pin of Fig.6 in place.
  • Fig. 1 shows a plan view of an actuator according to a first embodiment of the present invention.
  • a Base 7 supporting four terminals T1 1 at 3, T12 at 4, T21 at 5 and T22 at 6.
  • a first SMA wire 1 is mechanically attached and electrically terminated at its two ends to terminals 3 and 4
  • a second SMA wire 2 is mechanically attached and electrically terminated at its two ends to terminals 5 and 6.
  • a rigid electrically-insulating link 8 is attached to the midpoint of wire 1 at 9 and to the midpoint of wire 2 at 10.
  • link 8 is free to move relative to the Base 7, although its movement may be guided in a direction along a line between the wire centres 9 and 10 by any suitable mechanical means, e.g. a slot in the Base 7.
  • Any suitable mechanical means e.g. a slot in the Base 7.
  • the mechanical configuration shown in Fig.1 with the "midpoints" 9, 10 of the bowstrings 1, 2 facing inwards towards each other without the bowstrings overlapping is designated Inward Opposed Bowstrings or IOB.
  • This example illustrates a symmetrical and planar embodiment.
  • wire 1 is actuated (heated to Tmax and thus maximally contracted) and has total length 2Lh (the sum of length from 3 to 9 of length Lh, and from 9 to 4 also of length Lh), while wire 2 remains at or close to ambient
  • Fig. 2 shows the same actuator as Fig.1 but now with wire 1 unheated and close to ambient temperature and of total length close to its maximum value 2Lc, and wire 2 heated to Tmax and actuated and thus contracted close to its shortest length 2Lh. It will be seen that the nett effect of these changes is move the link 8 from left of centre (in Fig.1 ) to right of centre (in Fig.2) by an amount S (not shown), along the line of centres 9 and 10 of the wires 1 and 2.
  • Fig. 3 is to be interpreted as a geometrical representation of the same actuator as shown in Figs.1 and 2, where the capital letters (A, B, Q, Y, Z) are linear dimensions, and lowercase letters (a and b) are angles.
  • the following equations can immediately be written down:
  • Fig.4 illustrates an alternative geometry where the relevant equation for A, B, Z and Q is:
  • the two SMA-wires 1, 2 (see Fig. 5) forming the bowstrings of the opposed bowstring actuators can adequately be kept mechanically and electrically separated (e.g. by the insertion of a thin smooth insulating sheet between the wires, or alternatively by using smooth insulation-coated SMA-wires, or by mounting SMA- wires 1 and 2 above opposite faces of base 7) then the bowstrings or SMA-wires 1, 2 may overlap each other— this arrangement makes for a more compact actuator as can be seen from the smaller Base 7 (shorter in the Z-direction but by working within the design constraints can also be shorter in the Y-direction too).
  • An example of this form is shown in Fig.5.
  • the A, B, Q, Z relationship is:
  • k is generally in the range from ⁇ 3% to ⁇ 8% (a 100mm wire might be expected to reliably and repeatedly contract by at least 4mm when utilised optimally).
  • the dimension 2Q (the length of the Link) is a free variable and can be any convenient length that allows adequate mechanical separation of the two SMA-wire centres, together with proper mechanical coupling to the mechanical load to be moved by the actuator.
  • Q can usually be small compared with Zmax.
  • the actuator envelope size 2Ze in the Z direction is given by
  • the dimension A is calculated as
  • the example application is to move a tuning pin for an RF cavity or similar RF device.
  • the application specification is as follows: Output stroke: S>1 [mm]
  • 5.25x20x1 mm is possible.
  • a differently conservative design could increase angles a_min to 0.45rad and b_min to 0.35rad somewhat to reduce the output stroke to 1 .14mm and increase the minimum output force to ⁇ 59.9mN, with actuator envelope size for the three configurations IOB, OOB and AOB of 17.4x20x1 mm, 9.5x20x1 mm, 6.5x20x1 mm respectively.
  • the actuator total Y dimension can say 15mm when the design procedure results in, for example, a minimum force of 50mN with minimum stroke of 1 .17mm in actuator envelope sizes for the IOB, OOB and AOB configurations respectively of 1 1 .9x15x1 mm,
  • 6.7x15x1 mm and 3.7x15x1 mm alternatively, for example, a minimum force of 59.9mN and minimum stroke of 1 .05mm, and actuator envelope sizes for the IOB, OOB and AOB configurations respectively of 13.6x15x1 mm, 7.6x15x1 mm and 4.6x15x1 mm.
  • Fig.1 Fig.1
  • Fig.4 OOB
  • Fig.5 AOB
  • PCB printed circuit board
  • soldered-in crimp-terminals made of suitable metal e.g. phosphor bronze, or stainless steel, as the Terminals T1 1 ...
  • the actuator control electronics can easily and preferably be mounted on the same PCB.
  • SMA-wires of the correct (designed) length are then crimped between the terminals - alternatively the wire may be pre-crimped between the terminals, before they are added to the Base 7. In this case if the terminals are soldered into the Base then care must be taken to avoid overheating the SMA-wire crimped into the terminals.
  • Another alternative is to use a metal Base 7 fitted with insulated mounted terminals T1 1 ... T22, in which case a separate small PCB can be used to carry the control electronics with this then wired to the terminals, before or after terminal-insertion, as described above.
  • the link can be fabricated from any suitable insulating material such as PTFE, although much cheaper polymer alternatives able to withstand the maximum wire temperature of ⁇ 1 10C (or HOC or 160C, depending on the SMA material used) are available and known to those skilled in the art.
  • a low thermal conductivity material for the Link 8 is preferred, and also a material with low thermal capacity, in order to minimise heat loss from a heated SMA wire.
  • the material forming the Link 8 would most usefully be extended beyond the wire-centre point at one end of the link, and have the tuning pin directly attached at its far end, eliminating any mechanical bearings or levers or other rotary
  • Fig.6 shows a plan view of an example of an actual embodiment of the present invention, and is based on one of the design examples described herein above, which satisfies the real-application design specification.
  • This is an approximately-to- scale drawing where the top "9mm” and left “20mm” legends and dimension lines are dimension scales in mm. It can be seen that the overall actuator size envelope is approximately 20x9mm.
  • the Base 7 is a PCB and the four terminals 3, 4, 5, 6 are phosphor-bronze crimp-terminals, soldered into the Base PCB 7.
  • the two SMA-wires 1 and 2 are crimped into the terminal-pairs 3 & 4, and 5 & 6, respectively.
  • this novel double-opposed bowstring actuator in its various configurations and the design technique of the present invention provides a flexible and versatile actuator which can be tailored to various loads, strokes and mechanical layouts for a vast range of applications. It is particularly suited to the controlled movement of RF- cavity tuning pins, providing a compact, low power reliable actuator with no bearings and no moving parts to wear (only shape-changing components); other similar SMA- wire actuators have shown to be capable of reliable operation with over 500,000 to 5million complete cycles.
  • Fig.7 is a perspective schematic view of an embodiment of the present invention which is a double bowstring SMA-wire actuator connected to a tuning pin 130 for tuning an RF cavity (not shown).
  • 1 is an SMA wire, Wirel, of a first bowstring actuator, with its ends crimped at 20, 21 into mechanical and electrical terminals.
  • 2 is the SMA-wire Wire2 of a second, opposed, bowstring actuator.
  • Wirel engages with a first load attach pin 23 mounted in a push-rod 3 which is free to slide within the body 4, 4A, 4B of the actuator, along a line orthogonal to 20 to 21.
  • Wire2 similarly engages with a second load attach pin also mounted in the same push-rod 3, the bowstrings thus can jointly move the push-rod in either direction along its length, taking with it the tuning pin 130 attached to its end by bolt 25.
  • Fig.8 is a perspective schematic view of the actuator 143 of Fig.7 attached to the outside body of an RF tuning cavity 140 with RF connecting ports 141, 142 at either end.
  • Cavity 140 is shown cut away around the location of the RF tuning pin 130 which passes through a clearance hole in the cavity wall, preferably with electrical grounding means therearound to tightly couple the conductive portion of pin 130 with the conductive inner surface of cavity 140. It will be seen that by operating the actuator 143 the pin 130 will change the internal (electrical) geometry of the RF cavity and thus affect its resonances, as desired by this application.
  • Fig.9 is a close-up of the actuator 143 and the cut-away section of cavity 140 and showing the inside 146 of the cavity and the cut-away walls 145.
  • any of the SMA-wire actuators described above may be connected via an electrically insulated mechanical link to an RF tuning pin causing the tuning pin to move in and out of an RF cavity so as to adjust the electromagnetic tuning of the cavity.
  • Examples include the SMA-wire actuator comprising a straight section of SMA-wire connected in series to a mechanical spring which provides the return force for the return-stroke of the SMA-wire actuator cycle, or comprising two separate straight-wire SMA actuators mechanically connected in series, each actuator capable of providing the return force for the other during the other's return-stroke of its SMA-wire actuator cycle.
  • the two separate straight-wire actuators have similar or identical dimensions, and the wires of each are preferably aligned along the same line of direction.
  • the SMA-wire actuator is a bowstring- actuator with a mechanical spring to provide return force for the return stroke of the SMA-wire bowstring-actuator cycle, or more preferably comprises a pair of opposed bowstring-actuators mechanically connected in opposition.
  • a control system capable of measuring the resistance of each of one or two of the SMA-wires of the actuator embodiments, and from the measurement(s) of resistance said control system estimates the instantaneous length(s) of the SMA-wire(s), and from these length estimates together with knowledge of the specific actuator mechanical configuration is capable of estimating the output position of the actuator and thus able to accurately position the external load mechanically driven by the actuator.

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  • Manipulator (AREA)

Abstract

L'invention concerne un dispositif d'accord pour une cavité radiofréquence (RF) ou antenne RF, qui comprend un actionneur (7) couplé mécaniquement (8) à un élément d'accord (14), tel qu'une tige d'accord d'une cavité RF. L'actionneur est un actionneur à fil en alliage à mémoire de forme (AMF) pouvant effectuer un mouvement linéaire, relié par une liaison mécanique à une tige d'accord RF de manière que la tige d'accord puisse être déplacée par l'actionneur pour rentrer et sortir de la cavité RF. L'actionneur peut comprendre un fil AMF droit ou un fil AMF en corde d'arc fil couplé à un ressort de rappel, ou il peut s'agir d'un actionneur à fil AMF comprenant une paire d'actionneurs en corde d'arc opposés (1, 2) éliminant la nécessité d'un ressort de rappel et dont la méthodologie de conception permet une large plage de spécifications de performances et de tailles d'enveloppe.
PCT/GB2017/050454 2016-02-23 2017-02-22 Dispositif d'accord rf, actionneur et procédé WO2017144873A1 (fr)

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GBGB1603081.9A GB201603081D0 (en) 2016-02-23 2016-02-23 Actuator for small displacements
GB1603081.9 2016-02-23

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WO2017144873A1 true WO2017144873A1 (fr) 2017-08-31

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Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10616963B2 (en) 2016-08-05 2020-04-07 Nxp Usa, Inc. Apparatus and methods for detecting defrosting operation completion
GB2579425A (en) * 2018-11-30 2020-06-24 Hooley Tony Phase or frequency tuneable RF device exploiting properties of sma #03_3
US10771036B2 (en) 2017-11-17 2020-09-08 Nxp Usa, Inc. RF heating system with phase detection for impedance network tuning
US10785834B2 (en) 2017-12-15 2020-09-22 Nxp Usa, Inc. Radio frequency heating and defrosting apparatus with in-cavity shunt capacitor
US10917948B2 (en) 2017-11-07 2021-02-09 Nxp Usa, Inc. Apparatus and methods for defrosting operations in an RF heating system
US10952289B2 (en) 2018-09-10 2021-03-16 Nxp Usa, Inc. Defrosting apparatus with mass estimation and methods of operation thereof
US11039512B2 (en) 2016-08-05 2021-06-15 Nxp Usa, Inc. Defrosting apparatus with lumped inductive matching network and methods of operation thereof
US11039511B2 (en) 2018-12-21 2021-06-15 Nxp Usa, Inc. Defrosting apparatus with two-factor mass estimation and methods of operation thereof
US11166352B2 (en) 2018-12-19 2021-11-02 Nxp Usa, Inc. Method for performing a defrosting operation using a defrosting apparatus
US11382190B2 (en) 2017-12-20 2022-07-05 Nxp Usa, Inc. Defrosting apparatus and methods of operation thereof
US11570857B2 (en) 2018-03-29 2023-01-31 Nxp Usa, Inc. Thermal increase system and methods of operation thereof
US11800608B2 (en) 2018-09-14 2023-10-24 Nxp Usa, Inc. Defrosting apparatus with arc detection and methods of operation thereof

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2008099156A2 (fr) * 2007-02-12 2008-08-21 Cambridge Mechatronics Limited Appareil d'actionnement d'alliage à mémoire de forme
US20120104292A1 (en) 2010-10-27 2012-05-03 Gm Global Technology Operations, Inc. Active drain plug for high voltage battery applications

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2008099156A2 (fr) * 2007-02-12 2008-08-21 Cambridge Mechatronics Limited Appareil d'actionnement d'alliage à mémoire de forme
US20120104292A1 (en) 2010-10-27 2012-05-03 Gm Global Technology Operations, Inc. Active drain plug for high voltage battery applications

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
KEATS B F ET AL: "Shape memory alloy temperature compensation for resonators", 2003 IEEE MTT-S INTERNATIONAL MICROWAVE SYMPOSIUM DIGEST.(IMS 2003). PHILADELPHIA, PA, JUNE 8 - 13, 2003; [IEEE MTT-S INTERNATIONAL MICROWAVE SYMPOSIUM], NEW YORK, NY : IEEE, US, 8 June 2003 (2003-06-08), pages 1259, XP032412860, ISBN: 978-0-7803-7695-3, DOI: 10.1109/MWSYM.2003.1212598 *
SHAHRZAD JALALI MAZLOUMAN ET AL: "Square Ring Antenna With Reconfigurable Patch Using Shape Memory Alloy Actuation", IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, IEEE SERVICE CENTER, PISCATAWAY, NJ, US, vol. 60, no. 12, 1 December 2012 (2012-12-01), pages 5627 - 5634, XP011474831, ISSN: 0018-926X, DOI: 10.1109/TAP.2012.2213053 *

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10616963B2 (en) 2016-08-05 2020-04-07 Nxp Usa, Inc. Apparatus and methods for detecting defrosting operation completion
US11039512B2 (en) 2016-08-05 2021-06-15 Nxp Usa, Inc. Defrosting apparatus with lumped inductive matching network and methods of operation thereof
US10917948B2 (en) 2017-11-07 2021-02-09 Nxp Usa, Inc. Apparatus and methods for defrosting operations in an RF heating system
US10771036B2 (en) 2017-11-17 2020-09-08 Nxp Usa, Inc. RF heating system with phase detection for impedance network tuning
US10785834B2 (en) 2017-12-15 2020-09-22 Nxp Usa, Inc. Radio frequency heating and defrosting apparatus with in-cavity shunt capacitor
US11382190B2 (en) 2017-12-20 2022-07-05 Nxp Usa, Inc. Defrosting apparatus and methods of operation thereof
US11570857B2 (en) 2018-03-29 2023-01-31 Nxp Usa, Inc. Thermal increase system and methods of operation thereof
US10952289B2 (en) 2018-09-10 2021-03-16 Nxp Usa, Inc. Defrosting apparatus with mass estimation and methods of operation thereof
US11800608B2 (en) 2018-09-14 2023-10-24 Nxp Usa, Inc. Defrosting apparatus with arc detection and methods of operation thereof
GB2579425A (en) * 2018-11-30 2020-06-24 Hooley Tony Phase or frequency tuneable RF device exploiting properties of sma #03_3
US11166352B2 (en) 2018-12-19 2021-11-02 Nxp Usa, Inc. Method for performing a defrosting operation using a defrosting apparatus
US11039511B2 (en) 2018-12-21 2021-06-15 Nxp Usa, Inc. Defrosting apparatus with two-factor mass estimation and methods of operation thereof

Also Published As

Publication number Publication date
GB201700279D0 (en) 2017-02-22
GB201700278D0 (en) 2017-02-22
GB201603081D0 (en) 2016-04-06
GB201700281D0 (en) 2017-02-22
GB201700280D0 (en) 2017-02-22

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