HK1141258A - Microwire-controlled autoclave and method - Google Patents

Description

Microwire controlled autoclave and method

Cross Reference to Related Applications

This application claims the benefit of each of the following U.S. patent applications: S/N60/881,866 entitled "Microwire-Controlled Autoclave and Method" filed on 23.1.2007; S/N60/919,345 entitled "Microwire-Controlled service Warming System and Method", filed on 3, 22.2007; S/N11/745,348 entitled "magnetic element Temperature Sensors" (filed 5,7, 2007); and S/N12/018,100 entitled "Microwire-Controlled Autoclave and method" filed on 22.1.2008. the entire contents of each of the above applications are incorporated herein by reference.

Background

Technical Field

The present invention relates broadly to magnetic element temperature sensors, detectors using such sensors, closed loop object processing systems utilizing sensors and detectors to wirelessly determine temperature parameters associated with an object being processed, and corresponding methods. More particularly, the present invention relates to a closed loop molding/heating/curing system of the type used to fabricate composite parts such as aircraft and automotive parts, and including a wireless temperature parameter sensor/detector arrangement. Such systems include pressurized autoclaves, non-pressurized oven-type systems, and resin molding systems.

Background

Autoclave molding is an improvement over known pressure bag and vacuum bag molding techniques. Advanced autoclave compounding processes result in dense void-free molded parts due to more uniform and controlled heating and more uniform and controlled pressure conditions for part curing. This process is widely used in the aerospace industry to produce parts from pre-impregnated high strength fibers with high strength/weight ratios, such as parts used in aircraft, spacecraft and missiles. Autoclaves are essentially heated pressure vessels, usually equipped with a vacuum system, and designed to accept a composite lay-up placed on or in an internal mold. This stack is then heated and cured in an autoclave to form the final product. The curing pressure is typically in the range of 50 to 150psi, and the curing cycle time typically includes many hours. The autoclave process accommodates higher temperature matrix resins, such as epoxy resins, which have higher strength characteristics than conventional resins.

Resin Transfer Molding (RTM) is a low pressure, low emission, closed mold molding process for moderate volume production, filling the gap between slow, contact molding processes and faster compression molding processes that require higher tooling costs. In RTM, a continuous strand mat and woven reinforcement material are dry laminated to the lower mold half. Preformed glass reinforcement materials are often used in complex mold shapes. The mold is then closed and clamped, and the low viscosity resin and catalyst mixture is pumped into the mold, expelling air through strategically placed vent holes. The resin/catalyst ratio was controlled using a metered mixing device, the resin and catalyst were mixed using an motionless/static mixer, and then the mixture was injected into the die port. Common matrix resins include polyesters, vinyl esters, epoxies, and phenolics. RTM molded articles have a uniform thickness and present two smooth sides. To optimize the part surface finish, a gel coat may be applied to the mold surface prior to molding. High quality parts produced by RTM include automotive body parts, bathtubs and containers.

Other types of ovens may be used to perform the "pressure bag" or "vacuum bag" molding process. These furnaces cure composite parts with hot air, which is typically placed inside plastic bags or under thin plastic sheets that are sealed to the adjacent work surfaces. This allows the chamber formed by the plastic bag or sheet and the work surface to be evacuated.

In addition, repair procedures are often also performed on the uncured composite material portions (adjacent to the previously cured composite material) enclosed within the cavities formed by the thin plastic sheets. Also, within the chamber formed by the part and its encapsulated plastic "shroud" or "bag", a vacuum is typically drawn to remove air that may cause voids in the final cured repair. Heat may be applied to the uncured composite material by a number of methods, such as resistance heating blankets, hot air, high intensity light, microwaves, and induction heating of the carbon fibers or particles within the resin.

A continuing problem with all of the above techniques is the need to accurately monitor the temperature of the part during the heating, molding and/or curing cycle. In most production curing processes, only the air and/or tool temperature is monitored during the curing process, which follows a "recipe" of time and air/tool temperature predetermined by curing test parts that have embedded sensors within the part to correlate the part temperature with the air/tool temperature and dwell time. If a temperature sensor is used in a particular case to monitor the part temperature during the curing process of the part currently being produced (typically for curing of very thick parts), the temperature sensor is either a surface thermocouple applied at the strategically considered surface site or a conventional thermocouple embedded in an optional flash. In either case, if only temperature monitoring is its target, these thermocouples must be physically connected to a monitoring system, or for cure control purposes, these thermocouples must be physically connected to an autoclave, furnace, or RTM control system. Applying thermocouples to the parts and connecting them to the monitoring and/or control system is a complex and time consuming process that can also compromise the pressure integrity of the vacuum bag and/or autoclave. Whether used in autoclaves, ovens, or repair processes, the molding process of "pressure bags" or "vacuum bags" often utilizes thermocouple leads that extend through the vacuum bag device to externally monitored electronics. The leads that penetrate the vacuum bag or sheet often cause vacuum leaks that not only interfere with the maintenance of the desired vacuum level, but also allow moisture to enter the vacuum bag or sheet, resulting in poor curing results.

Accordingly, there is a need in the art for improved object processing devices and methods that include wireless temperature parameter sensing that allows for non-contact monitoring of objects, such as parts and part precursors, within a chamber in real-time to determine temperature parameters during object processing (e.g., heating, molding, and/or curing), thereby allowing for the use of closed-loop feedback to control the processing device without any type of sensor lead. Furthermore, it would be advantageous if these sensors could be placed deep within a thick part and the wireless detector (reader) could be remote from the part so as not to interfere with the curing process. Finally, it would be advantageous if the sensor could remain within the produced part for the duration of the part's life after curing without causing any structural damage to the part.

Disclosure of Invention

The present invention overcomes the problems described above and provides an improved apparatus for treating an object which includes wirelessly sensing a temperature parameter associated with the object during treatment of the object. Broadly, the apparatus of the present invention comprises a chamber configured to receive an object to be treated, wherein the object has an associated magnetically susceptible microwire sensor element operable to sense a parameter related to the temperature of the object during treatment thereof. The apparatus also has a detector including an antenna assembly proximate the chamber, the antenna assembly operable to generate an alternating magnetic field in the region of the object sensor and to detect the magnetic response of the sensor as a measurement of the temperature-related parameter. The sensor(s) are embedded inside the composite part, preferably within the resin layer of the inner layer of the CFRP composite structure, as these sensors can be read wirelessly by a reader through the carbon layer. The sensors may be placed manually within the composite part during curing or repair, or may be placed within the composite layer earlier in the manufacturing process, such as during pre-preg material manufacturing.

In various preferred forms, the device of the invention is one or more selected from the following group of devices: an autoclave chamber, a resin transfer mold, a non-pressurized oven, and a pressure bag or vacuum bag assembly. In the case of autoclaves, the chamber is in the form of a thick-walled pressurizable chamber formed with a flexible bag, sheet or lid and usually an adjacent substrate, with or without a bag assembly placed in a furnace or autoclave (the bag assembly is often heated for repair by a hot air blower, a resistive element in a heat blanket placed against the bag assembly, high intensity lamps, and many other heat sources). The antenna assembly may be partially or fully located within the chamber, or may be located outside the chamber. However, in all of these cases, the antenna assembly (antenna or antennas) is oriented within a position relative to the object sensor so as to allow interrogation of the sensor by the alternating magnetic field generated and to detect the characteristic magnetic response of the sensor.

During the processing cycle, the device controller uses sensed temperature-related parameters that are detected and/or calculated by decoding electronics associated with the antenna assembly (the decoding electronics, power supply, transmit and receive electronics, and antenna assembly collectively forming a "reader") to establish and maintain appropriate processing conditions for the object. The reader typically uses a microprocessor to decode the re-magnetized signal information collected by the receiving antenna. The decoding algorithm may be a best fit formula that relates the re-magnetization information obtained by the sensor to the actual temperature experienced by the sensor, or may be look-up table information that has been pre-calculated from the best fit formula or determined empirically. The decoding algorithm can simply exploit the fact that: the curie temperature of each magnetic element sensor causes the re-magnetization response to disappear when the sensor temperature exceeds the curie temperature, or the fact that: the parameters of this re-magnetization response (such as the detected voltage value, voltage pulse shape, pulse duration, etc.) vary in a very predictable and easily discernable manner, and the sensor temperature is within a small temperature range below the curie temperature of the sensor. In either case, the reader outputs the temperature parameter into the microprocessor of the controller of the device for control purposes (the reader and the controller of the device may also share the same microprocessor if both the decoding algorithm and the control algorithm of the device are present). Preferably, the temperature parameter is selected from the group of parameters; the temperature of the object, the desired temperature of the object, the temperature range of the object, the desired temperature range of the object, the minimum temperature of the object, the maximum temperature of the object, the heating characteristics of the object, and the temperature of the material supported by the object.

In a particularly preferred form, the sensor comprises a magnetically sensitive sensor microwire element having a re-magnetization response under the influence of an applied alternating magnetic field, wherein the re-magnetization response is defined by at least one short, detectable pulse of magnetic field perturbation of defined duration and is different at least one set point temperature below and above about 400 ℃. Furthermore, the detectable magnetic field perturbation pulse varies in easily detectable characteristics such as the magnitude, shape and time of the detection voltage over a small temperature range preceding the curie temperature, so that after regularization with respect to a reference pulse from another microwire whose characteristics do not vary within the required sensor temperature range, quantifiable values can be deduced from these detectable characteristics associated with the exact temperature experienced by the sensor. For example, by integrating the voltage of the detected pulse over time, regularizing the resulting values, and comparing the regularized values to the values of a look-up table associated with the sensor temperature (or performing the actual correlation calculations in real time), an accurate temperature can be detected by the magnetically sensitive sensor microwire element in a small temperature range (typically 40 to 50 ℃) below the curie temperature above which no remagnetized pulse is detected.

In addition, preferred sensors include a plurality of microwire sensor elements, at least some of which have a Curie temperature different from other sensor elements. By arranging the different curie temperatures such that each different curie temperature is adjacent to a small temperature range of the nearest (curie temperature-wise) companion sensor element, the temperature can be effectively detected, thereby allowing a sensor with continuous temperature measurement capability over a temperature range from about 40 ℃ below the curie temperature of the lowest curie temperature microwire sensor element up to the curie temperature of the highest curie temperature sensor element. Of course, the reader's decoding electronics may use an algorithm that detects only when the re-magnetization pulse of each sensor disappears at its corresponding curie temperature (hereinafter referred to as a "simple decoding algorithm"), or may use a more complex algorithm that determines the sensor temperature between the curie temperatures of successive elements (hereinafter referred to as a "complex decoding algorithm"). The microwire elements are typically fabricated from amorphous or nanocrystalline metallic materials as elongated metallic filaments or strips having a maximum cross-sectional dimension of about 100 μm. Preferred metals are selected from the following group of alloys: iron-based alloys, cobalt-based alloys, and mixtures thereof, with chromium or other elements therein that can adjust the curie temperature of such alloys. The metal body typically has a glass coating around the wire or strip. The sensor of the present invention is typically placed in thermal contact with the object to be treated by applying the sensor to the surface of the object or embedding the sensor in the object.

Various objects can be treated according to the invention, in particular high-value automotive or aircraft parts or part precursors made of composite and/or synthetic resin materials. Such parts or part precursors can typically be processed in a closed chamber apparatus using molding, heating and/or curing processes.

Drawings

FIG. 1 is a partial view, partially in section, showing a prior art magnetic microwire element suitable for use in the present invention;

FIG. 2 is a graph of the magnetic characteristics of microwires suitable for use in the present invention at temperatures below the Curie (Curie) temperature of the microwire alloy;

FIG. 3A is a graph of time versus re-magnetization of amorphous ribbons typically used in conventional EAS markers or tags for shoplifting protection;

FIG. 3B is a graph of time versus remagnetization of amorphous microwires with large Barkhausen discontinuities that can be used in a marker or label commercially available from Sensormatic corporation (Sensormatic Co.);

FIG. 3C is a graph of time versus re-magnetization of glass-coated amorphous magnetic microfilaments produced by the Taylor process;

FIG. 4 is a cross-sectional view of a magnetic temperature sensor attached to an object to be sensed in accordance with a first embodiment of the present invention;

FIG. 4A is a principal schematic cross-sectional view similar to FIG. 4, but showing components of a magnetic microwire temperature sensor designed to be spliced between two objects placed in close proximity to each other;

FIG. 5 is a schematic cross-sectional view of a temperature sensing element according to a second embodiment of the present invention, showing a glass coated amorphous microwire magnetic element surrounded by a cylindrical sheath of ferromagnetic metal or ferrite material and having a desired Curie temperature;

FIG. 6 is a principal schematic cross-sectional view of a magnetic temperature sensor according to the present invention utilizing a microwire data element of the type shown in FIG. 1 and a temperature sensing element as shown in FIG. 5;

FIG. 7 is a schematic cross-sectional view of another temperature sensing element according to a third embodiment of the present invention, wherein a glass coated microwire magnetic element is as shown in FIG. 1 and is positioned adjacent a shield of ferromagnetic metal or ferrite material having a desired Curie temperature;

FIG. 8 is a principal schematic cross-sectional view of a magnetic element temperature sensor according to a third embodiment of the present invention including the data element shown in FIG. 1 and the temperature sensing element shown in FIG. 7;

FIG. 9 is a graph showing Curie temperature versus the percentage copper content of a nickel-copper alloy suitable for use as a sheath for a temperature sensing element according to the second embodiment of the invention or as a shield for a temperature sensing element according to the third embodiment of the invention;

FIG. 10 is a schematic block diagram of a temperature reader in accordance with the present invention, which is operative to interact with a magnetic element temperature sensor;

FIG. 11 is a schematic diagram showing a closed loop feedback temperature controlled induction heating unit based on a magnetic element sensor according to the present invention;

FIG. 12 is a schematic diagram showing an autoclave equipped with a closed loop temperature feedback device in accordance with the present invention; and

figure 13 is a schematic diagram showing a vacuum bag processing chamber with portions of a closed loop temperature feedback device (reader antenna and sensor) according to the present invention.

Detailed Description

Magnetic element and detection system of the prior art

For a better understanding of the present invention, it is helpful to understand the characteristics and operation of today's EAS and authentication systems using magnetic elements (often referred to as "magnetic markers") and their corresponding detection systems.

One type of magnetic element that is often used is a glass-coated amorphous microwire. Such microfilaments, their production, magnetic properties and behavior below the curie temperature are disclosed in the technical and patent literature. For example, see U.S. Pat. Nos.6,441,737 and 6,747,559; preparation and Characterization of Glass-covered magnetic Wires, by Horia Chirac (Preparation and Characterization of Glass coated magnetic Wires), "Materials Science and Engineering (Materials Science and Engineering), A304-306, 166-71 (2001); donaled et al, "Preparation, characterization and application of certain Glass-Coated Metal Filaments Prepared by Taylor wire Process (The Preparation, Properties and applications of Glass Coated Metal Filaments Preparation by The Taylor Process)", (Journal of Materials Science, 31, 1139-48 (1996); wiesner and Schneider, "Magnetic Properties of Amorphous iron-phosphorus Alloys Containing gallium, germanium and arsenic" (Magnetic Properties of Amorphous Fe — P Alloys containment Ga, Ge, and ands), "physics. And "High Frequency Properties of Glass-coated microwires" by Antonenko et al, "Journal of Applied Physics, Vol.83, 6587-89. Continuous filamentary segments have been produced at low cost by a process commonly referred to in the art as the taylor process whereby pre-alloyed ingots or desired base constituents are melted within a substantially vertically disposed glass tube sealed at the bottom. Once the alloy is converted to the molten state, it is heated using radio frequency ("rt") to grip the softened bottom of the glass tube and draw it into a continuous microfilament. The cross-section of the alloy is rapidly reduced while using a second cooling means, causing the alloy to become amorphous or nanocrystalline during drawing.

A typical microwire 20 is shown in fig. 1, having an overall diameter of from ten microns or less to tens of microns. Microwire 20 has an alloy core 22 and a glass coating 24, wherein alloy core 22 and glass coating 24 may be physically coupled to each other continuously or only at several spatially separated points. Although the glass to metal ratio can vary, it can be closely controlled. For example, a typical thickness of the glass coating 24 may be about 1-5 microns for a 45-60 micron core diameter microwire, and typically about 1-3 microns for a30 micron core diameter microwire. The microfilament elements used in prior art EAS and identification tags are typically cut to lengths ranging from 15mm to 75 mm.

The magnetic properties of the microwires and the resultant hysteresis loop can be controlled by varying the composition of the alloy and the ratio of glass to metal diameters. Fig. 2 shows the ideal magnetic hysteresis loop response of a typical microwire 20 having a large barkhausen discontinuity suitable for use in the present invention described below. When such microwires 20 are exposed to an externally alternating magnetic field, the magnetic field strength in the direction opposite the instantaneous magnetic polarization of the element is greater than the coercivity H_cWhere the coercivity is ideally shown to be less than 10A/m, the re-magnetization process results in the generation of strong harmonic pulses that are easily detected. The change in flux during the pulse causes a peak in the time derivative of the flux. Thus, a voltage peak is seen in the receiver coil placed near the element, readingThe device may correlate the voltage peak to the presence of a microwire element within the magnetic field.

The glass-coated amorphous microwires 20 produced by the taylor process of the prior art can be made to exhibit: very low coercivity (substantially less than 10A/m), high relative permeability (substantially higher than 20000), substantially zero or slightly positive magnetostriction, and large barkhausen discontinuities (which means that the microwires are substantially only present in the two-state magnetic state).

The re-magnetization characteristics of the microwires 20 are also important and distinguish such microwires from other types of prior art magnetic elements. Referring to FIG. 3C (see U.S. Pat. No.6,556,139), it can be seen that for glass coated amorphous microwires, the re-magnetization peak width (measured at half-amplitude height) is in the range of 25-80 microseconds. In contrast (see fig. 3B), the marker or tag available from Sensormatic includes an underwater cast amorphous wire with large barkhausen discontinuities, with peak widths in the range of about 200-500 microseconds or more. Finally (see FIG. 3A), for amorphous strips of markers or labels commonly used for shoplifting protection (e.g., the Meto GmbH 32-mm marker or label), the peak width is about 1-2 milliseconds. Thus, microwires of the type shown in fig. 1 exhibit extremely short remagnetization peaks, which allows the response of the microwire to be discerned from background noise, such as that caused by fields interacting with other external objects.

Zhukov et al j. mater.res.15no.10 month (2000) describes the production of multi-bit marks using multiple amorphous glass-coated microwire segments, each segment having a different size (length, hair diameter, etc.) or magnetic properties (e.g., coercive field). For example, if multiple magnetic microwire elements exhibit different coercivities, respectively, then their unique re-magnetization peaks can be detected during each magnetic field period, for example, by identifying their patterns using the method described in U.S. Pat. No.4,203,544. U.S. Pat. No.5,729,201 describes a method of distinguishing such multiple microwires even if they have the same magnetic properties and dimensions. The permanent magnet bias field elements in the vicinity of the microwires serve to distinguish the magnitude of the external magnetic field generated by the reader, which is required to pass through its proximity to each individual microwire segment to varying degrees, while exceeding the coercivity of each magnetic element re-magnetization. This results in a phase difference of the re-magnetization peaks that can be detected, thus allowing to distinguish the individual elements.

U.S. patent No.4,134,538 describes a multi-element tag (marker) constructed of magnetic elements, each element characterized by a different coercivity, thereby allowing any attached object to be given as many reference codes as there are magnetic elements utilized. Once the magnetic elements have thus been given the respective characters of the reference code in the order of their respective coercivity values, the signals corresponding to the respective magnetic elements appear in the detection device in the same order of phase shift as the order of coercivity values, and the amplitude of each signal corresponds to the value given at the time of encoding, thus reproducing the complete code in terms of arrangement and amplitude.

U.S. patent No.6,622,913 teaches that microwire elements of different diameters or permeability may be used to encode data information into binary form so that they produce substantially different responses to the alternating magnetic field produced by the transmitter. Thus, one type of microwire may be a binary "0" while the other is a binary "1". For example, an array of four microwires, each with a continuously larger coercivity such that they are each readily distinguishable by the phase difference they detect over a period of time of the associated alternating magnetic field, can be made to produce alternating high and low amplitude magnetic field perturbations (and alternating high and low voltage amplitudes within the detector), and thus represent a binary pattern 1010.

U.S. patent application No.2005/0109435 describes several magnetic and optical methods for encoding multiple bits of information on a single microwire. The stress sensitivity of ferromagnetic amorphous glass-coated microwires can be advantageously used as a physical basis for influencing the magnetic domain structure. The ferromagnetic amorphous glass-coated microwire code can be formed by local alternation of the magnetic domain structure. This alternation can be easily achieved by applying local stresses or selective crystallization of amorphous alloys. This variation is affected by a number of measures, including local heating by pulsed lasers, chemical thinning of the glass coating, coatings on the glass, etc. Localized modification of the coated glass of the ferromagnetic amorphous coated glass microwires can be used to effectively produce controlled changes in the domain structure of the amorphous alloy core, thereby enabling encoding. A preferred method is to use laser pulses to locally heat the glass or alloy (independent heating can be achieved by selection of wavelengths) causing a structural change in one or both of the two, thereby altering the existing stress field or the basic magnetic properties.

The detector devices of the prior art EAS or authentication systems used with all types of magnetic elements used as magnetic markers typically use a magnetic field transmitter unit and a magnetic field detector unit. The field transmitter typically has a frequency generator and a field generator coil (together forming an alternating magnetic field source) for generating an alternating magnetic field in the interrogation zone of the marker. The detector unit usually has a field receiving coil and a signal processing unit which usually triggers an alarm device.

In prior art EAS systems, the interrogation AC field causes the magnetization of the switching magnetic element to switch when the magnetic marker is positioned near the coil. Thus, the field receiving coil receives a very short pulse of magnetic field perturbation. These pulses are detected by a signal processing circuit which generates an output to activate an alarm.

The first embodiment: microwire of modified chemistry for curie temperature sensing

A first microwire embodiment of the present invention comprises a magnetic microwire temperature sensor having at least one and typically a plurality of magnetically sensitive microwires, each alloy of at least some of the microwires having a modified chemical property and a consequent different curie temperature, typically less than about 400 ℃. In addition, this embodiment includes a microwire reader/detector that can decode temperature information obtained from the sensor microwire. As noted, the reader/detector may use a "simple decoding algorithm" that returns discrete temperatures obtained from the sensor, which correspond to the curie temperature of each magnetically sensitive microwire. Alternatively, the reader/detector may use a "complex decoding algorithm" that returns successive temperatures derived from the sensor corresponding not only to the curie temperature of each of the included magnetically sensitive microwires, but also to temperature information derived from discernable changes in pulse parameters between the curie temperatures of successive temperature-sensing microwires.

Each microwire that is chemically modified is preferably processed so that the modified microwire retains a large barkhausen discontinuity, an extremely low coercivity, and an extremely high permeability (with a resultant hysteresis characteristic of the type shown in fig. 2) below its corresponding curie temperature. These modified microfilaments substantially completely lose their ferromagnetic properties above their curie temperature. The other microwires within the sensor array need not have modified chemical properties but can operate as data elements according to any of the prior art methods of single or multiple bit codes described above.

The optimal chemical modification of iron-based and/or cobalt-based alloys used in prior art amorphous microwires is to adjust the atomic percent of chromium therein. Chromium in amorphous iron-based (Fe80-xCrx) (PC)20 alloys has a large effect on their magnetic properties. An increase in the percentage of chromium reduces the curie temperature, the average hyperfine field and its saturation magnetization, on the other hand, significantly increasing its initial permeability. For example, in some samples, an increase in chromium percentage from 0% to 6.5% decreased the Curie temperature from 330 ℃ to 155 ℃. It can be seen that "magnetic measurements of chromium-containing iron-rich amorphous alloys" by Henry et al: mossbauer research and B-H loop (Magnetic Measurements of Iron-Rich Amorphous allergy continuous Chemium: Mossbauer Study and B-H Loops), "Journal of materials Science (Journal of materials Science) 19: 1000-06 (1984); and "Magnetic Properties of metal-d-Elements, Alloys and Compounds" by Wiin (Magnetic Properties of Metals-d-Elements, Alloys, and Compounds) ", Springer Press, Berlin (1991).

Other chemical changes to the iron-based and cobalt-based alloys may also be used to alter the magnetic properties of the amorphous microwire elements. For example, cobalt can replace iron in certain FCZBN Alloys, and the resulting Curie temperature exhibits a sinusoidal behavior With increasing cobalt content, With two maxima at 3 and 12.5 atomic percent of cobalt and a minimum at 7.5 atomic percent of cobalt (Co Dependence of Curie temperature in Amorphous FeCoZrBNB With High Glass forming ability (Co Dependence of Co Dependence of Current temperature in Amorphous Fe Co Zr B Nb With High Glass forming ability) by Yao et al, Journal of physical Science: reduced edition Vol.166325-34 (2004)). A process is proposed in institute of Electrical and electronics Engineers (IEEE transactions on Magnetics), Vol.22, 1349-51(1986), whereby amorphous cobalt-phosphorus (Co-P) alloys with high phosphorus content can be obtained electrolytically. The curie temperature of these alloys shows a linear behavior of curie temperature with up to 28-29% phosphorus composition. For higher concentrations, a constant curie temperature was observed.

As mentioned above, the first embodiment preferably utilizes a plurality of magnetic microwire temperature sensing elements whose chemical properties have been altered such that the microwire becomes paramagnetic at various temperatures (typically above or below 400 ℃) throughout a particular design temperature range of the temperature sensor. For example, FIG. 4 shows a temperature sensor 26 having a total of four temperature sensing microwires 28-34 forming an array 36. Each microwire 28-34 has a chemical property that is modified using any of the processes described above, such as increasing the atomic percent of chromium, with the result that the curie temperature of the individual microwires is not identical and is exceeded during the temperature range of normal operation of the sensor 26. The remaining two microwires 38 and 40 are data elements. An optional permanent magnet biasing field element 41 may also be used.

In the embodiment of fig. 4, the microwires 28-34 are arranged in a parallel relationship wherein the spacing 42 is equal to the sum of the radii of each adjacent microwire (the spacing 42 can be greater than the sum of the radii), and the microwires 28-34 are held together with a thermally conductive adhesive (not shown) that also bonds the microwires to an object 44 whose temperature is to be monitored.

In this exemplary embodiment, the magnetic coercivity of each of the individual microwires 28-34 and 38-40 is varied by appropriate chemical modification in their alloys, specifically the chromium content of each alloy, to ensure that each of the six microwires can be uniquely sensed in its positional order within the entire array during each time period. Of course, other prior art processes for altering the alloy chemistry and adjusting the coercivity can be used for this purpose. Furthermore, each of the six microwires 28-34 and 38-40 is equal in length (e.g., 20mm) except for the microwire 38, except that the microwire 38 is particularly longer (e.g., 40 mm). The extra length of the microwire 38 ensures that the re-magnetization peak detected from the data element microwire is greater in magnitude than the other re-magnetization peaks.

Fig. 10 illustrates an exemplary detector arrangement 46 for detecting the temperature sensed by sensor 26, which corresponds to the temperature of object 44. The detector 46 broadly comprises an alternating magnetic field transmitter unit in the form of a frequency generator 48 coupled to a field generator coil 50, so that operation of the transmitter unit creates an alternating magnetic field to the interrogation sensor 26. The overall device 46 also includes a field receiving coil 52 operatively coupled to a digital signal processing unit 54 and a temperature display 56. As shown, the processing unit 54 is equipped with communication ports 58 and 60 and is operably coupled to the frequency generator 48 by a connector 62. Furthermore, the frequency generator 48 may be equipped with an optional input device 61 allowing remote control of the generator.

The digital signal processing unit 54 operates using a decoding algorithm that has the ability to decode the magnetic field perturbation information received by the interrogation sensor 26. Preferably, according to the invention, the decoding algorithm is in the form of one or more look-up tables for the different sensors, which are stored in a memory associated with the unit 54. In the case of detector 46, which is dedicated to sensor 26, its signal processor unit 54 uses a "simple decoding algorithm" that the temperature look-up table will have the expected phase (phase relationship derived from the stop bit and/or from each other) for each of the four temperature sensing microwire elements 28-34, as well as the temperature reported from the array 36 of microwires 20 to each acceptable detected bit code (some bit codes may be unacceptable because they are not logically sensed according to the curie temperature phasing microwire sequence, and are therefore the product of misreading by detector 46). In the case where the signal processing unit 54 of the detector 46 uses a "complex decoding algorithm", the look-up table includes all of the information used in the "simple decoding algorithm", as well as the unique regularized pulse parameter values and the correlated temperatures (with a selected interval between the temperatures) for each temperature in a small range of temperatures below the curie temperature. Thus, for example, if an acceptable bit code derived from the array 36 of microwires 20 is determined by the digital signal processing unit 54 using a "complex decoding algorithm", the digital signal processing unit 54 will access a portion of the lookup table correlating pulse parameter values to sensor temperatures between the curie temperature of the microwire at the highest curie temperature whose re-magnetization pulse has disappeared and the curie temperature of the microwire at the lowest curie temperature whose re-magnetization response is still detectable. The "complex decoding algorithm" allows the signal processing unit to compare the currently detected and calculated pulse parameter values with said suitable range of values in the look-up table to reach the temperature of the sensor: the sensor temperature is a high resolution within a small range of temperatures below the curie temperature of the microwire, which is now discernable to reach a temperature below the lowest curie temperature at which its re-magnetization response is still detectable.

As described above, the sensor 26 and detector device 46 are interrelated such that the device 46 ascertains the temperature of the object 44 by appropriate interrogation of the sensor 26. Such correlation typically includes at least the bit logic of sensor 26 matching a decoding algorithm, which in this case is a temperature look-up table stored in the memory of signal processing unit 54. Those skilled in the art will recognize that a wide variety of bit logic and corresponding algorithm tables may be provided for both the "simple decoding algorithm" and the "complex decoding algorithm" described herein. However, the following discussion provides an exemplary system using a "simple decoding algorithm" for the case of the sensor 26 and detector arrangement 46 of FIG. 10.

Referring again to FIG. 4, assume that the least significant bit of the four temperature sensing element microwires 34-38 is microwire 28, which may be designated as the "first" microwire. Thus, when the object 44 is below the curie temperature of the first microwire 28, the microwire 28 will still produce its characteristic short re-magnetization pulse under the influence of the alternating magnetic field produced by the device 46. Thus, when the object 44 has a Curie temperature higher than the first microwire 28, the microwire 28 will no longer produce its short re-magnetization pulse under the influence of the applied alternating magnetic field, and its bit will therefore be missing from the bit array of the detected temperature sensing cell (the "0" value).

The remaining temperature sensing element microwires 30-34 each have a corresponding chemically modified alloy such that the curie temperature of the microwires is successively and in a stepwise manner slightly higher than the curie temperature of the first microwire 28. Thus, the "second" microwire 30 has a curie temperature slightly higher than that of the first microwire 28, while the "third" and "fourth" microwires 32 and 34 each have a subsequent curie temperature slightly higher than that of the lower-order microwire. Thus, at respective temperatures above the curie temperature of the first microwire 28 and the curie temperatures of all preceding microwires of lower order, the re-magnetization pulses (bits) of the microwires 30-34 will disappear (i.e., become a "0" value) under the influence of the magnetic field applied by the detector 46.

For example, if the temperature of the object 44 is below the Curie temperatures of the first and second microwires 28 and 30, all bits of the array 36 will be read by the device 46 (i.e., become a "1" value). If the temperature of the object 44 is above the Curie temperature of the first microwire 28 but below the Curie temperature of the second microwire 30, the first bit will disappear to the device 46 as a "0" value and the remaining bits corresponding to the microwires 30-34 will be read by the device 46 as a "1" value.

As noted above, the device 46 contains an algorithm in the form of a look-up table that identifies the absence of the first temperature bit and the presence of the second and all higher temperature bits means that the temperature of the object 44 lies somewhere between the first and second Curie temperatures of the first and second microwires (temperature bits) 28 and 30 (as used herein, the detection or determination of the temperature of the sensor or object may be referred to as a single temperature or an approximate temperature within a temperature range). Thus, by reading the temperature-sensing bit data generated by the array 36 and correlating the binary value of that data with the look-up table of interest, the temperature of the object 44 can be determined within a temperature range defined by the interval between the first and second microwire Curie temperatures. Of course, this logic applies to all four microwires 28-34 of the simple example of FIG. 4.

If the number N of temperature sensing microwires on a given magnetic element temperature sensor has identified curie temperatures of a known incremental sequence, and these curie temperatures are selected to coincide with one another to some extent at least in their increments, the sensor can detect temperatures from the first through nth curie temperatures. The resolution of such sensors, which employ a "simple decoding algorithm" by the comparison reader, is the increment between sequential curie temperatures. It should be appreciated that even if the sequential curie temperatures do not exactly coincide, an associated look-up table can be constructed and the sensor can function properly. It should be appreciated that in the case of a reader using a "complex decoding algorithm", the resolution achieved is much greater and is determined by many factors such as the accuracy of the best fit equation.

The curie temperature of the microwire alloys of this embodiment can be quantified before or after the alloy is processed into microwires. In addition, detectable changes in the re-magnetization pulse occurring below the Curie temperature can quantify and regularize factors such as read distance and transmitter field strength in a carefully controlled environment. A complete microwire sensor can calibrate temperature sensing in this manner.

In the event that a certain temperature sensing microwire does not occur in the proper sequence with other microwires (due to misreading of the reader/detector, lack of thermal contact with other microwires, or other reasons), the lack of an acceptable look-up table value preferably causes the reader/detector algorithm of the device 46 to attempt to read the sensor 26 again. If successive rereads show the same irregular temperature data, the reader/detector algorithm may erase the temperature data, use the last measured temperature (or the last measured temperature plus a temperature difference based on calculations, including the last measured temperature rate of change and the read time interval), and then try again in the next scheduled read interval. Preferably, various steps are taken to ensure that all of the microwires are in good thermal contact with each other and with the object 44 whose temperature is to be measured. One such step is to attach all the microwires to a thin, thermally conductive substrate. Another step is to use a thermally conductive housing or potting material as described below.

As many as 40 microwires are known to detect over a period of time, the magnetic element temperature sensor of this embodiment can therefore contain many more than four temperature-sensing microwires 20 and many more than one (not counting the stop bits) data element. Particularly if each data element is encoded with multiple bits of data, the data elements may be used to store cross-correlation information (such as constants for linear or non-linear relationships) that may allow the detector algorithm to decode "special values" (temperature bits) to their associated temperature values. This is particularly valuable in situations where a look-up table approach is not used. Thus, magnetic element temperature sensor 26 may store data such as a permanent ID code or an "object level" code in its data element. This ability to store the "object level" code allows a single reader/detector algorithm to read several different types of wire temperature sensors, each with its own unique look-up table, and still decode the exact temperature.

It should be appreciated that given that each temperature sensing microwire is designed to lose its re-magnetization pulse characteristics above the curie temperature under the influence of the alternating magnetic field generated by the device 46, a number of different encoding/decoding number strategies may be used in the sensor 26 and the device 46 without departing from the scope of the present invention. One option is to use a biasing magnetic field element 41 which is used to distinguish the magnitude of the external magnetic field generated by the device 46, which magnitude needs to exceed the coercive force of the re-magnetization of each microwire due to the different proximity of the magnetic field element to the individual microwires 28-34 and 38-40. This results in a phase difference within the re-magnetization peak detected by the detector 46, thus facilitating the discrimination of six distinct microwires. Other variations may include determining a stop or "delineation" bit between the temperature sensing element and the data element without a limiting device, encoding and decoding of non-temperature data, and varying the length of some or all of the microwires to alter the magnetic response of the microwires. Furthermore, the change in magnetic properties at certain temperatures near the curie temperature of each temperature sensing microwire may change, but not completely eliminate its detectable pulse of re-magnetization. Such a changed re-magnetization pulse having predictable characteristics over a particular temperature range at the curie temperature may also be used to decode the temperature information. This may allow each temperature sensing microwire to accurately sense more than one temperature, e.g., from a cell below the curie temperature up to the curie temperature, when a "complex decoding algorithm" is used within the decoding electronics of the reader.

Second embodiment: microwire with ferromagnetic sheath for temperature sensing

This second embodiment includes a magnetic element temperature sensor 64 having a plurality of composite temperature sensing microwires 66, each microwire comprising a magnetically susceptible microwire of the prior art type described above, which does not intentionally reduce the curie temperature to maintain its large barkhausen discontinuity and other magnetic properties as shown in fig. 2 throughout the operating range of the sensor 64. The microwire structure further includes a surrounding tubular structure 68. The entire second embodiment also includes a microwire temperature probe similar to probe 64 with a stored algorithm capable of decoding temperature information derived from interrogation of sensor 64.

In particular, each composite microwire 66 has an innermost alloy 70 surrounded by an intermediate glass coating 72 so that the inner portion of the composite microwire 66 is conceptually identical to the prior art microwire 20 described above. In addition, the structure 68 of the microwire 66 includes a tubular sheath 74 of ferromagnetic metal or ferrite material (such as NiZn or MnZn) surrounding the coating 72, and an optional outermost glass coating 76 surrounding the tubular sheath 74. The sheath 74 has a curie temperature carefully selected so that the individual inner microwire alloys 70 produce their characteristic perturbations (and thus the re-magnetization voltage pulse at the detector) only when the microwire is placed within the alternating magnetic field produced by the detector, and then only above the curie temperature of the ferromagnetic sheath 74 (or above some temperature near the curie temperature). Thus, when the composite microwire 66 is subjected to a temperature below the curie temperature of the ferromagnetic sheath 74 (or below a temperature near the curie temperature), the sheath 74 is ferromagnetic, thereby altering the characteristic pulse of the microwire 66. This may prevent re-magnetization of the composite microwire 66 due to magnetic saturation by the sheath 74, or may allow the generation of a re-magnetization signal that is biased or "altered" from the composite microwire 66. For example, the re-magnetization pulse may be out of phase with its position above the sheath curie temperature, or the biasing effect of the sheath may allow for a changing re-magnetization response at temperatures below and above a number of different set points.

When the composite microwire 66 is subjected to a temperature above the curie temperature of the sheath 74, the sheath becomes paramagnetic and thus has no effect on the signal pulse of the alloy 70. Thus, above the various curie temperatures of the sheath 74 (or above certain temperatures near these curie temperatures), the composite microwires 66 function normally (i.e., they cause the detector 46 to detect voltage pulses, as envisioned in phase, amplitude, etc., as recorded in a look-up table, or by some other decoding algorithm). However, when the composite microwire 66 experiences certain temperatures below the respective curie temperatures of its sheath 74, the microwire is either not detectable by the detector or is detectable but has a change in its magnetic properties, particularly with respect to signal pulses detected above the temperature of the curie temperature of its sheath 74. The magnetic properties so changed may not fit the parameters of the look-up table if the reader uses a "simple decoding algorithm", or may be used to correlate to a temperature below the curie temperature if the reader uses a "complex decoding algorithm".

If the material comprising the tubular sheath 74 is a ferromagnetic metal, the sheath 74 may be only a few microns thick, or the thickness required to saturate the inner microwire alloy 70 and achieve manufacturability. One method of forming the ferromagnetic sheath 74 can be seen in U.S. patent No.7,011,911 entitled "Amorphous Microwire and method for manufacturing same". Other methods include flame spraying or jetting. When these methods are used to form the jacket 74, the outermost coating 76 is not necessarily required. A modified taylor method may also be used in which an inner glass tube and an outer glass tube are coaxially and telescopically aligned so that the inner glass tube is located within the outer glass tube wall. Alloy 70 is in ingot (rod) or component metal form within the central glass tube, and the material comprising tubular sheath 74 is located between the two mating glass tubes. The jacket material may be in the form of an ingot (possibly several rods) or a component metal. The alloy is melted by heating it with magnetic induction or other suitable means and the resulting molten metal and glass are rapidly drawn out to form the composite microwire 66.

Various techniques are known in the art for adjusting the curie temperature of ferromagnetic alloys by adding trace elements of specific metals. Thus, any number of alloys may be used to construct the tubular sheath 74. Fig. 9 shows that adding a small amount of certain metals (in this case copper) to a ferromagnetic metal element (in this case nickel) to form a true alloy can change the curie temperature of the resulting ferromagnetic alloy in a predictable manner. Also, small amounts of chromium added to iron can result in alloys with predictable curie temperatures. See U.S. patent No.5,954,984, which discusses the use of copper and aluminum to correct the curie temperature of nickel.

The alloy or ferrite material from which the tubular sheath 74 is fabricated may have a Curie temperature (or a conditioning temperature near its Curie temperature) quantified before or after the alloy or ferrite material is processed into the tubular sheath 74. Thus, the magnetic element temperature detector 46 can be easily calibrated for temperature sensing. As before, for a given temperature range to be measured, the more temperature sensing composite microwires the sheath curie temperature quantifies and is distributed approximately equally spaced over the temperature range, the higher the resolution of the temperature sensor. Preferably there are at least 20 temperature sensing composite microwires 66 each having a sequentially increasing sheath curie temperature up to 5 ℃ above the next lowest sheath. Of course, if the sheath 74 changes the re-magnetization pulse of the microwires 66 over a temperature range near the curie temperature of the sheath 74 (e.g., by a detectable phase shift of the re-magnetization pulse), the detector can sense and decode multiple temperatures for each microwire 66 within a certain range using a "complex decoding algorithm", thus requiring fewer microwires 66 for the sensor to accurately measure temperature over a wide range.

If the material comprising the tubular sheath 74 is ferrite or some other mixed material with ferrite, the sheath may be attached to a glass layer 72, separate cylindrical edges, or other sintered ferrite cylindrical object with a central hole so that the alloy 70 and surrounding glass 72 may be placed therein. Alternatively, the tubular sheath 74 may be formed as part of the glass layer 72 by using a glass-ferrite material for the glass layer 72 instead of using pure glass. U.S. patent No.6,909,395 entitled "radar absorbing coating" describes a ferrite/glass composite material that can be used to attach directly to a wire or other shaped metal object, or to a layer of pure glass that has been attached to the metal.

Referring now to fig. 6, the sensor 64 includes a plurality of microwires 20 in a data element array 78 and a plurality of temperature-sensing composite microwires 66 forming a composite microwire array 80. The microwire 20 and the composite microwire 66 are attached to a sensor or label substrate 82 that is as thin and thermally conductive as possible to place the sensor 64 in close thermal contact with an object (not shown) for temperature measurement.

The microwires 20 comprising the array 78 have various chemistries that impart respective curie temperatures above the projected operating temperature range of the sensor 64, which is typically less than about 400 ℃. The composite microwires 66 within the array 80 are preferably spaced apart by a distance 84 such that once the ferromagnetic or ferrite tubular sheath 74 of each composite microwire 66 experiences a temperature above its curie temperature, the ferromagnetic or ferrite tubular sheath 74 of each composite microwire 66 does not affect its adjacent composite microwire.

In this simple embodiment, in which the reader uses a "simple decoding algorithm," it is assumed that each data element of the array 78 is laser encoded to a logic state of either a "1" or a "0". Further, assume that each data element is equal in length (e.g., 20mm), with the exception of terminating elements 83 and 86, which are relatively long (e.g., 40 mm). This extra length ensures that the magnitude of the re-magnetization peak detected from data elements 83 and 86 is greater than the magnitude of the other data elements. Finally, assume that data element 83 is laser encoded to a logical value of "1" and data element 86 is laser encoded to a logical value of "0". As described in the first embodiment, the individual elements of the two arrays 78 and 80 are made: the detected phase order matches the illustrated ordering from top (microwire 83) to bottom (composite microwire 88) with the highest sheath curie temperature of the composite microwires of array 80. In this case, the detector 46 assigns the highest amplitude with a logic level "1" as the start bit to the first detected pulse (in phase relation) (shown here as microwire 83), and assigns the highest amplitude with a logic level "0" as the stop bit to the last detected data microwire 86. All data microwires between start and stop bits 83 and 86 are detected as data bits by the microwire temperature reader/detector. As described in the first embodiment, for various functions such as tag identification number and "object level" coding, an inserted data microwire may be employed.

To decode the temperature information from the sensor 64 using the example of a "simple decoding algorithm", it is assumed that there are "N" composite microwires in the slave array 80 that have ferromagnetic sheaths 74 such that all of the respective sheaths 74 have Curie temperatures that are exceeded during the normal operating range of the sensor 64 (or have conditioning temperatures "close" to the Curie temperatures). The least significant bit of these N composite microwires 66, which in phase relationship is detected just after the stop 86 and in a particular phase relationship away from the stop 86, is considered the "first" composite microwire 89. Thus, the first composite microwire 89 will only begin to produce its normal short-pulse perturbation at temperatures above the Curie temperature of its sheath 74, and thus, the detector 46 will only detect its voltage pulse (bit). The first composite microwire 89 will not produce the normal short pulse perturbations at a temperature below the curie temperature of its sheath 74, and therefore its bits will either be lost from the bits detected by the detector 46, or its pulses will change to be clearly detectable by the detector 46 as a "changed" microwire.

A "second" composite microwire 90, in a phase relationship from the stop 86 (the immediately least significant bit), has a ferromagnetic sheath 74 with a curie temperature slightly higher than that of the composite microwire 90. The bit of the composite microwire 90 will not be read by the detector 46 at temperatures below the higher sheath curie temperature (or higher temperatures near the curie temperature of the sheath), or its voltage signal will be detected as "varying", but the bit of the composite microwire 90 will appear as expected in phase and duration at temperatures above the temperature of the first composite microwire 89.

Thus, if the sensor 64 is subjected to a temperature below the curie temperature (or a specified temperature below the curie temperature) of the first and second composite microwires 89 and 90, then the composite microwires will not be detected by the detector 46 (assuming all subsequent higher-order composite microwires within the array 80 have sheaths 74 with higher curie temperatures). If the sensor 64 is subjected to a temperature above the sheath curie temperature (or related temperature) of the first composite microwire 89 but below the sheath curie temperature (or related temperature) of the second composite microwire 90, the detector 46 will read the first bit but the second bit will not be read by the detector 46 or it will have an "altered" signal that is read by the detector. Finally, if the sensor 64 is subjected to a temperature above the curie temperature (or related temperature) of the sheaths of the first and second composite microwires 89 and 90, both the first and second composite microwires will be read by the detector 46.

The detector 46 contains a "simple decoding algorithm" that recognizes the presence of the first temperature bit of the first composite microwire 89, but the absence (or change) of the second temperature bit of the second composite microwire 90, and thereby sends a signal via the display 56 indicating that the sensor temperature exists somewhere between the first sheath curie temperature and the second sheath curie temperature. Thus, if the sensor 64 is placed in close thermal contact with an object whose temperature is of interest, the detector 46, by reading the output of the composite microwire array bits of the sensor 64, determines that the object temperature is within a temperature range defined by the interval between the first and second sheath curie temperatures (or between their respective temperatures near their curie temperatures).

If the number of composite microwires 66 on a sensor 64 having a sheath curie temperature known as an increasing sequence is increased to "N" composite microwires and the sheath curie temperatures are selected to coincide with one another to some extent at least in increments thereof, the sensor 64 has a detectable temperature range of sheath curie temperatures from first to nth and has a temperature resolution defined by the increment between successive sheath curie temperatures.

More generally, the detector 46 decoding algorithm is configured to recognize that the presence of the first through N-1 th temperature bits produced by the respective composite microwire 66 in its normal pulsed state, and the absence of the Nth temperature bit corresponding to the Nth composite microwire 66 in its normal pulsed state, determines that the sensor temperature is at a temperature between the N-1 th sheath Curie temperature and the Nth sheath Curie temperature (or between respective temperatures near its sheath Curie temperature). The detector algorithm preferably reports the sensor temperature as an intermediate temperature between the nth-1 and nth curie temperatures.

Preferably, the acceptable composite microwire position combination and its corresponding sensor temperature are stored in a look-up table in the memory of the detector 46. Thus, when the detector 46 detects an acceptable combination of bits from an associated sensor 64, the pattern is compared to a look-up table to find the correlated sensor temperature. Also, either a "simple decoding algorithm" or a "complex decoding algorithm" may be used by the reader, wherein the "complex decoding algorithm" uses the altered pulse information as has been described earlier herein.

In the event that one or more of the composite microwires 66 of the array 80 does not appear in its normal state in proper sequence with the other microwires (due to misreading by the detector 46, lack of thermal contact with the other composite microwires, or for some other reason), the detector algorithm preferably attempts to read the sensor 64 again. If successive rereads show the same irregular bit pattern, the detector algorithm may discard the temperature data, use the last measured temperature (or the last measured temperature plus a temperature difference based on a calculation that includes the last measured temperature rate of change and the read time interval), and then try again at the next scheduled read interval.

The third embodiment: microwire with separated but adjacent ferromagnetic saturation elements for temperature sensing

The third embodiment is very similar in concept to the second embodiment except that a saturation or biasing element of a ferromagnetic sheath is used as a separate entity that does not need to contact the surface of the microwire adjacent to the sensed temperature as compared to the case where the sheath 74 in the second embodiment is bonded or otherwise attached to the microwire central structure. Referring to fig. 7, there is shown a combined microwire 92 comprising a microwire 20 of the type described above that does not specifically reduce its curie temperature so that it will maintain its large barkhausen discontinuity and other magnetic properties as shown in fig. 2 over the full operating range of the sensor. Again, the combined microwire 92 includes adjacent ferromagnetic sheaths 94. The sheath 94 is positioned sufficiently close to the associated microwire 20 to prevent magnetic saturation or biased re-magnetization of the microwire 20, and consequent sign difference perturbation, until the combined microwire 92 experiences a temperature above (or some temperature near) the curie temperature of the sheath 94. Also, as in the case of the second embodiment, the sheath 94 may be designed such that the associated microwire 20 exhibits a series of different re-magnetization responses at set point temperatures below and above the sheath Curie temperature, so that a plurality of different responses may be used for temperature sensing and temperature determination, if desired.

More specifically, the sheath 94 is preferably in the form of a rectangular sheet of ferromagnetic metal that is no significantly wider than the width of the associated microwire 20, the flat surface of which may be bent into a semi-circle (or in the case of ferrite, may be sintered into a semi-circle or some other suitable shape). The curie temperature of the sheath 94 is carefully selected so that when the combined microwire 92 is placed within the alternating magnetic field of the detector 46, and only when the combined microwire 92 experiences a temperature above the curie temperature of the sheath 94 (or is detectable at a temperature range above some fixed temperature near the curie temperature), the associated microwire 20 is caused to generate its signal perturbation (and hence re-magnetization pulse of voltage). The sheath 94 need only be a few microns thick or as thick as is necessary for saturation of the associated microwire 20 and for ease of manufacture. The same type of alloy or ferrite as described in connection with the second embodiment may also be used for the manufacture of the sheath 94. In addition, magnetic inks (using ferromagnetic or ferrite powders) are also suitable and have the advantage that the support substrate incorporating the microwires 92 can be printed.

Referring to fig. 8, a temperature sensor 96 is shown which is identical in all respects to the sensor 64, except that a combination microwire 92 is used in place of the composite microwire 66. Accordingly, the same reference numerals are used in fig. 8 in fig. 6 to identify like components, and the designation "a" is used to distinguish the combined microwire 92 from the composite microwire 66. The operation of the sensor 96 is identical to the operation of the sensor 64 and utilizes a similar detector 46 associated with the sensor 96 with a suitable decoding algorithm, preferably a look-up table.

The three embodiments described above, as well as other embodiments within the scope of the invention in practice, may be varied in many different respects. For example, FIG. 4A illustrates an alternative configuration that may be advantageous for certain product applications. Specifically, in fig. 4A, a sensor 26a is provided in which a microwire data element 40 is attached to a first object 44A, while the remaining data microwires 38 and temperature-sensing microwires 28-34 and optional biasing element 41 are attached to a second object 44 b. The bit logic of sensor 26a is the same as that of sensor 26, meaning that even if the components of sensor 26a are separated onto objects 44a and 44b, the entire sensor 26a will only operate when all of the sensor components are within the alternating magnetic field generated by detector 46. If this condition does not exist, an unsuccessful read using the detector 46 may occur. This configuration may be used, for example, to control the heating of two-part objects by a heater, so long as the detector of the heater detects both parts of the sensor (and thus both objects 44a and 44b) and prevents any heating accordingly, unless both parts of the sensor are present and within the magnetic field of the detector 46. In such a case, the control of the heater may typically be combined with the signal processing unit 54 of the detector 46.

Of course, this same design concept can be used when there are more than two objects present. In addition, more sophisticated data encoding methods, as described above, may be used to correlate one or more components of the entire sensor 26a with their matching components. Such a method may include laser encoding the first data element 40 and employing a matching multi-bit encoding for the stop data bits 38.

Although the alternative configuration of fig. 4A is described with reference to the first embodiment of the sensor 26, it will be appreciated that the same modifications can be made to the second and third embodiments of the sensors 64 and 96, if desired.

As with the microwires 20 of sensor 26, the microwires forming a portion of sensors 64 and 96 can be attached to object 44 or a heat-transferring substrate (such as substrate 82) using a suitable adhesive. In another alternative configuration, the microwires 20, composite microwires 66 and/or composite microwires 92 can be encapsulated in a very thin non-ferromagnetic heat-transfer material, e.g., a graphite-filled polymeric material, which can be molded by compression or injection, such as sold by the SGL Carbon company (SGL Carbon) under the trade name SGL CarbonOne of a family of materials sold. Other useful high temperature materials include ceramic potting material sold by Aremco corporation (Aremco) under the trade name Ceramancast 510, or other flexible high temperature polymers. With such a material, the thickness and the overall thermodynamic mass of the sheath material should be kept to a minimum in order to keep the object to be temperature monitored and the alloy core of the microwire between themWith minimal thermal delay therebetween.

Furthermore, the microwires of the described embodiments can be twisted into threads or woven into the structure of the object whose temperature is to be monitored, if appropriate. For example, the microwires can be woven into a carbon cloth fabric so long as it maintains good thermal contact, and suitable processing means can be used to distinguish the individual temperature-changing elements from each other and from the individual clearly identified data elements (to include a stop bit).

Closed-loop feedback autoclave, furnace and resin transfer molding system for composite part creation

The wireless magnetic element temperature sensor and associated probe of the present invention can readily replace thermocouple wires used in prior art closed loop feedback processing devices such as autoclaves, ovens, resin transfer molding systems, and vacuum bag/heating systems used in repair processes.

Referring to fig. 11, a conventional closed loop heating system 98 includes the microwire detector 46 (see fig. 10) incorporated into an induction heating apparatus 100 in place of an RFID reader. The apparatus 100 includes a control microprocessor 102 operatively coupled to the detector 46, the solid state converter 104 and the rectifier 106, and the induction coil 108 coupled to the converter 104. An AC power source 109 and current sensor 109a are operably coupled to the rectifier 104. The field generators and receive coils 50 and 52 are integrated into a sensor component 110 located below the support element 112.

The system 98 is designed to control the temperature of a graphite heating disk 114, such as described in U.S. patent No.6,657,170, having one or more embedded microwire sensors 116 of the present invention. The disk 114 has graphite layers 118, shown above and below the sensor 116. Of course, any other inductively heatable object may be controlled instead of the puck 114, such as a multi-layer cooking appliance (e.g., a pot or pan) having one or more sensors 116 embedded therein. The detector 46 detects feedback of temperature information from the sensor 116, which can be used to control the inductive heating of the puck 114 by the control microprocessor 102. Further, any type of heating device or heating system, such as a heating furnace, autoclave, or resin transfer molding press, may be substituted for the induction heater of this example, as long as temperature information from the probe 46 is used by the heating device to control its energy output.

For example, in fig. 12, the autoclave 120 is shown in a state where the door is opened. The autoclave 120 includes a thick-walled autoclave chamber 122 supported by a base 124. The chamber 122 has a circular back wall 126 and a similarly configured front closing door (not shown). Internally, the autoclave chamber 122 is equipped with a mounting bracket 128 that supports a parts platform 130. Conventional steam inlets and heating elements (not shown) are provided with the chamber 122 to establish and maintain suitable temperature and pressure conditions therein. In addition, the autoclave 120 includes a pair of microwire reading antennas 132, 134 located within the chamber 122. The respective antennas 132, 134 are mounted on support rods 136, 138, which are axially adjustable by means of sealing sliding mounts 140, 142. The antennas 132, 134 are operably connected to an external probe 144. The detector 144, in turn, is operatively coupled to a controller 146 of the autoclave microprocessor, the controller 146 being designed to control the process temperature within the chamber 122.

Composite part 148 is positioned within chamber 122 and rests atop platform 130. The part 148 has a series of elongate embedded microwire sensors 150 of the type described above. Although not shown, it should be appreciated that the parts 148 may also be located within the bag and bottom positioned within the autoclave chamber such that a vacuum condition may be established within the bag to eliminate voids within the finished parts.

During processing of part 148, antennas 132, 134 move position relative to part 148, allowing appropriate interrogation and reading of sensor 150 as described above. Of course, additional antennas may be used, and may be divided into a transmitting antenna for generating the alternating interrogation magnetic field and a corresponding detector antenna operable to detect the re-magnetization response of sensor 150. Temperature parameter information detected from sensor 150 may be used by autoclave controller 146 to maintain appropriate temperature and pressure conditions within chamber 122 during processing of part 148.

Fig. 13 illustrates some type of vacuum bag apparatus 152. Such apparatus is typically used in autoclaves, furnaces or other enclosed structures, but in a slightly modified form it may be used in repair processes. The apparatus 152 includes a chamber 153 formed by a tooling base 154 (which is replaced by part of the part itself during repair) with a flexible sheet or cover 156 attached to the base 154 by a peripheral seal 158. The base 154 and cover 156 cooperatively form an interior object handling area 160. A vacuum head 162 is located within the region 160 and extends outwardly through a conduit 164 to a vacuum source (not shown). A microwire reader antenna 166 is positioned outside the cover 156 and is operably coupled to a detector (not shown) by leads 168.

In the illustrated embodiment, a part 170 is supported on the base 154 with an optional intermediate release layer 172 positioned between the bottom side 170 and the base 154. The part 170 has a plurality of elongate microwire sensors 174 embedded therein. A breather 176 is positioned atop the part 170 with a release layer 178 therebetween.

In use, temperature and vacuum conditions are established and maintained within the region 160 in various ways, for example, by heating of the base 154 and evacuation of the head 162. During the process cycle, the antenna 166 interrogates the sensor 174 by generating a suitable alternating magnetic field and detects the re-magnetization response of the sensor 174. The information thus detected is then used by the overall microprocessor controller of the device 152 for process control purposes, or for simply monitoring the temperature of the part, to control heating by manual methods or in a manner known in the art.

Each patent and literature reference referred to herein is specifically and entirely incorporated by reference.

Claims (46)

1. Apparatus for treating an object, the apparatus comprising:

a chamber configured to receive an object to be treated, wherein a magnetically sensitive microwire sensor element is provided, the microwire sensor element being associated with the object and being operable to sense a parameter related to a temperature of the object during treatment thereof; and

a detector comprising an antenna assembly proximate the chamber, the antenna assembly operable to generate an alternating magnetic field in the sensor region and to detect a magnetic response of the sensor as a measurement of the parameter.

2. The apparatus of claim 1, wherein the temperature parameter is selected from a group of parameters comprising: a temperature of the object, a desired temperature of the object, a temperature range of the object, a desired temperature range of the object, a minimum temperature of the object, a maximum temperature of the object, a heating characteristic of the object, and a temperature of a material supported by the object.

3. The apparatus of claim 1 wherein said sensor elements comprise magnetically sensitive sensor elements having a re-magnetization response under the influence of an applied alternating magnetic field, said re-magnetization response being defined by at least one short detectable pulse of magnetic field perturbation of defined duration and being different at least one set point temperature below and above about 400 ℃.

4. The apparatus of claim 3, wherein there are a plurality of said sensor elements, at least some of said sensor elements having a set point temperature different from others of said sensor elements.

5. The apparatus of claim 3, wherein the setpoint temperature is a Curie temperature of the sensor element.

6. The apparatus of claim 3, wherein the sensor element has different re-magnetization responses above and below a plurality of different set point temperatures.

7. The apparatus of claim 6, wherein the plurality of different setpoint temperatures are below the Curie temperature of the sensor element.

8. The apparatus of claim 1, wherein the sensor element comprises a metal body.

9. The apparatus of claim 8, wherein the metal body is amorphous.

10. The device of claim 8, wherein the metal body is nanocrystalline.

11. The device of claim 8, wherein the metal body is in the form of an elongated wire or strip having a maximum cross-sectional dimension of up to about 100 μm.

12. The apparatus of claim 8, wherein the metal body is made of an alloy selected from the group consisting of: iron-based alloys, cobalt-based alloys, and mixtures thereof.

13. The apparatus of claim 12, wherein the alloy has chromium therein.

14. The apparatus of claim 1, wherein the sensor element comprises a metal body having a glass coating therearound.

15. The device of claim 1, wherein the sensor element comprises a metal body with a ferromagnetic sheath disposed adjacent to the metal body.

16. The apparatus of claim 1, wherein the element comprises a metal body having: a coercivity of less than 10A/m, a relative permeability of greater than 20,000, a magnetostriction of substantially 0 or small positive values, and a large barkhausen discontinuity.

17. The apparatus of claim 15, wherein the element comprises a metal body that produces a characteristic re-magnetization pulse above the curie temperature of the adjacent ferromagnetic sheath and produces no re-magnetization pulse or a modified re-magnetization pulse at one or more temperatures below the curie temperature of the adjacent ferromagnetic sheath.

18. The apparatus of claim 1, wherein the object is a part or a part precursor.

19. The apparatus of claim 1, wherein the chamber is selected from the group of chambers consisting of: an autoclave chamber, a resin transfer mold, and a pressure bag or vacuum bag assembly.

20. The apparatus of claim 19, wherein the chamber is an autoclave chamber, and the probe assembly comprises at least one antenna located within the autoclave chamber, the antenna being operably coupled to a probe outside the autoclave chamber.

21. The apparatus of claim 19, wherein the chamber is a pressure bag or vacuum bag assembly and the detector assembly includes an antenna positioned outside the pressure bag or vacuum bag assembly.

22. A combination, said combination comprising:

an object processing chamber;

an object to be treated positioned within the chamber;

a magnetically sensitive microwire sensor element associated with the object within the chamber and operable during the object processing to sense a parameter related to the temperature of the object; and

a detector comprising an antenna assembly proximate the chamber, the antenna assembly operable to generate an alternating magnetic field in the sensor region and to detect a magnetic response of the sensor as a measurement of the parameter.

23. The combination of claim 22, wherein the object comprises a part or a part precursor.

24. The combination of claim 22, wherein the temperature parameter is selected from the group of parameters consisting of: a temperature of the object, a desired temperature of the object, a temperature range of the object, a desired temperature range of the object, a minimum temperature of the object, a maximum temperature of the object, a heating characteristic of the object, and a temperature of a material supported by the object.

25. The combination of claim 22 wherein said sensor element comprises a magnetically sensitive sensor microwire element having a re-magnetization response under the influence of an applied alternating magnetic field, said re-magnetization response being defined by at least one short detectable pulse of magnetic field perturbation of defined duration and being different at least one set point temperature below and above about 400 ℃.

26. The combination of claim 22 wherein there are a plurality of said sensor elements, at least some of said sensor elements having a set point temperature different from others of said sensor elements.

27. The combination of claim 26, wherein the setpoint temperature is the curie temperature of the sensor element.

28. The combination of claim 26 wherein said sensor elements have different re-magnetization responses above and below a plurality of different set point temperatures.

29. The combination of claim 28, wherein the plurality of different setpoint temperatures are below the curie temperature of the sensor element.

30. The combination of claim 22, wherein the sensor element comprises a metal body.

31. The combination of claim 30 wherein said metal body is amorphous.

32. The combination of claim 31, wherein said metal body is nanocrystalline.

33. The combination of claim 30, wherein said metal body is in the form of an elongated wire or ribbon having a maximum cross-sectional dimension of up to about 100 μm.

34. The combination of claim 30, wherein the metal body is formed from an alloy selected from the group consisting of: iron-based alloys, cobalt-based alloys, and mixtures thereof.

35. The combination of claim 34, wherein the alloy has chromium therein.

36. The combination of claim 22, wherein the sensor element comprises a metal body having a glass coating therearound.

37. The combination of claim 22, wherein the sensor element comprises a metal body, and a ferromagnetic sheath is disposed adjacent the metal body.

38. The combination of claim 22, wherein the element comprises a metal body having: a coercivity of less than 10A/m, a relative permeability of greater than 20,000, a magnetostriction of substantially 0 or small positive values, and a large barkhausen discontinuity.

39. The combination of claim 38, wherein the element comprises a metal body that produces a characteristic re-magnetization pulse above the curie temperature of the adjacent ferromagnetic sheath and produces no re-magnetization pulse or a modified re-magnetization pulse at one or more temperatures below the curie temperature of the adjacent ferromagnetic sheath.

40. The combination of claim 22, wherein said chamber is selected from the group of chambers consisting of: an autoclave chamber, a resin transfer mold, and a pressure bag or vacuum bag assembly.

41. The combination of claim 40, wherein the chamber is an autoclave chamber, and wherein the probe assembly comprises at least one antenna located within the autoclave chamber, the antenna being operably coupled to a probe outside the autoclave chamber.

42. The combination of claim 40, wherein the chamber is a pressure bag or vacuum bag assembly, and the detector assembly includes an antenna positioned outside the pressure bag or vacuum bag assembly.

43. A method of at least partially controlling an object handling process within a closed chamber, comprising the steps of:

providing a chamber configured to receive an object to be processed, wherein a magnetically sensitive microwire sensor element is associated with the object and is operable to sense a parameter related to the temperature of the object during processing of the object;

generating an alternating magnetic field in the region of the sensor;

detecting a response of the sensor element to the generated magnetic field and using the detected response to determine, at least in part, the parameter; and

using the detected parameter to at least partially control the process.

44. The method of claim 43, wherein the chamber is selected from the group of chambers consisting of: an autoclave chamber, a resin transfer mold, and a pressure bag or vacuum bag assembly.

45. The method of claim 43, wherein the treatment process is selected from the group of treatment processes consisting of: heating, molding and curing processes.

46. The method of claim 43, wherein the detected response is a re-magnetization response of the sensor element.