EP0128601A1 - Dispositif de contrôle de température - Google Patents

Dispositif de contrôle de température Download PDF

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Publication number
EP0128601A1
EP0128601A1 EP84200654A EP84200654A EP0128601A1 EP 0128601 A1 EP0128601 A1 EP 0128601A1 EP 84200654 A EP84200654 A EP 84200654A EP 84200654 A EP84200654 A EP 84200654A EP 0128601 A1 EP0128601 A1 EP 0128601A1
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EP
European Patent Office
Prior art keywords
wire
input
circuit
resistance
change
Prior art date
Legal status (The legal status 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 status listed.)
Ceased
Application number
EP84200654A
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German (de)
English (en)
Inventor
John Vandorpe
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Katholieke Universiteit Leuven
Original Assignee
Katholieke Universiteit Leuven
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 Katholieke Universiteit Leuven filed Critical Katholieke Universiteit Leuven
Publication of EP0128601A1 publication Critical patent/EP0128601A1/fr
Ceased legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B17/00—Fire alarms; Alarms responsive to explosion
    • G08B17/06—Electric actuation of the alarm, e.g. using a thermally-operated switch

Definitions

  • the invention relates to a device for warning against the passing of a temperature value, e.g. an undercooling or overheating warning device such as a fire alarm system or a warning system for electrical cable overheating.
  • a temperature value e.g. an undercooling or overheating warning device such as a fire alarm system or a warning system for electrical cable overheating.
  • an undercooling or overheating warning device such as a fire alarm system or a warning system for electrical cable overheating.
  • a temperature monitoring device comprising a wire made of shape memory alloy, and a circuit having an input coupled to said wire and being responsive to a rate of change of the electrical resistance of the wire above a threshold value to generate a warning indication of the passing of a temperature value.
  • Shape memory alloys have the property that their resistivity slowly rises with rising temperature, but only outside their transformation temperature range, because within that range these alloys show a steep resistivity fall over about 10 to 20 % of the value.
  • a measuring circuit registers a rate of resistance drop above a threshold value, this means then that the wire temperature is rising through the transformation temperature range.
  • the resistivity falls slowly with falling temperature outside the transformation temperature range of a shape memory allow, but shows a similar steep rise inside that range.
  • rate of resistance rise above a threshold value this means then that the wire temperature is falling down through the transformation temperature range.
  • Such range can be chosen by taking the right wire alloy and the measuring circuit consequently will produce a warning signal which can be sent to any warning instrument, such as a generator of a visual or audible alarm signal, via the necessary amplifiers and/or relays, or to a computer, etc. It is however not necessary that the whole wire be heated to obtain an alarm signal. When only one tenth is heated, the sudden rise or fall will be of 1 to 2 %, and this can also be measured for producing the alarm signal.
  • the wire can then be laid in tunnels along lengths of 10 to 50 metres, or along electrical cables to avoid overheating, or along the parts of a combustion or other motor in tortuous forms to monitor the temperature of the different parts, and so on. As soon as a part of the wire is then overheated, the alarm signal is produced.
  • Shape memory alloys are alloys having a martensitic phase at lower temperature and an austenitic phase at higher temperature, with a narrow transformation range between both, of which the breadth ranges in the order of 20 to 70°C and capable of producing a shape memory effect.
  • these alloys it was earlier discovered that, when they are deformed in the martensitic state from an original shape to another shape, and then heated into their austenitic state, they recover either partially or totally their original shape during the transformation from martensite to austenite, and when they are cooled down again to the martensitic state, they take again the said other shape.
  • Ternary alloys of Cu-Al-Zn are also known with 8-structure in the austenitic state, of which the content (as shown in the ternary diagram), lies inside the trapezoidal form determined by the four corners, expressed in percentages by weight of Cu, Al and Zn respectively, A (64 ; 1 ; 35), B (74 ; 5 ; 21), C (87.5 ; 12.5 ; 0) and D (86 ; 14 ; 0).
  • quaternary alloys of Cu-Al-Zn are known, being the ternary alloy of the compositions above, to which a small amount in the range between 0 and 2.5 % of some other material is added, such as cobalt or nickel or boron. Such ternary or quaternary alloys are called hereinafter "shape memory Cu-Al-Zn alloys”.
  • Figure 1 shows, as an example, the variation as a function of temperature of the resistivity of a wire, of 1.5 mm diameter and 0.738 metre length, made of an alloy No. 1222 comprising 70.3 % Cu, 24.9 % Zn, 4.4 % Al and 0.4 % Co.
  • the resistivity rises from about 0.088 micro-Ohm-metre ( ⁇ m) to about 0.090 ⁇ m.
  • the starting temperature of the transformation to Austenite (A s -temperature) lies for this alloy at about 30°C.
  • the resistivity falls rapidly down towards a minimum of about 0.076 ⁇ m, and then rises again as the A f -temperature, the temperature where the transformation to Austenite is finished, is passed.
  • the alloy undergoes the inverse transformation to Martensite with a certain hysteresis, starting the transformation at the M s -temperature (in this case at about 58°C) and finishing the transformation at the M f -temperature as shown in the drawing.
  • the transformation range of a shape memory alloy is the range between M f and A f , in this case between about 20 and about 80°C, the range having in this example a breadth of about 60°C.
  • the temperature level of the transformation can be chosen by adapting the alloy composition as indicated in Fig.2.
  • the Ms-temperature as a function of the composition is given in Figure 2.
  • Ni When added, it must be taken into account that the latter slightly increases the M s -temperature, whereas adding Co or B have less influence on this diagram.
  • an alloy will be chosen having an M s -temperature between 30°C and 150°C.
  • the wire of shape memory alloy will in general have a diameter in the range between 0.1 mm and 2.5 mm, although not exclusively.
  • the wire need not necessarily have a circular cross-section, but the latter may be rectangular or have any other shape, including the shape between two concentric circles, the "wire” having then a tubular form.
  • wire is consequently meant any elongated form with a length dimension of larger order of magnitude than the largest dimension perpendicular thereto, e.g. at least 100 times larger.
  • the length of the wire will depend on the order of magnitude of length of the zones where overheating or undercooling is expected, the percentage of resistance drop or rise produced by the transformation of martensite or austenite, or austenite to martensite, of the alloy, and on the sensitivity to which the measuring apparatus has been set. For instance, for a fire alarm in a tunnel, a fire overheating length of about 3 metres can be expected, and for an alloy of e.g. 12 % resistivity-drop, and an instrument set to register a 1 % resistivity-drop in 15 seconds of transition through the transformation range, a length of 36 metres can be taken. In applications where the whole of the length is overheated, there is in principle no limit of length.
  • the overheating zone is of the order of a few centimetres, as in monitoring motor parts or short-circuits in electrical conductors, the usual wire length will range in the order of 0.5 to 3 metres.
  • wire lengths in the range between 3 and 50 metres can be used, and if the circuit can be preset with a sufficiently low threshold value, but still without responding to slower drift signals, the length can even go up to 100 metres.
  • FIG. 3 shows an example of an overheating warning signal generator.
  • a circuit responsive to an excessive rate of resistance drop comprises an operational amplifier 4 and a wheatstone bridge 9.
  • the output voltage V o of the amplifier 4 is fed back to the input, on one hand via feedback resistance 3, on the other hand via a feedback circuit 20 comprising a clock-pulse generator 5, an up-down counter 6, and a digital-to-analog converter 7, delivering an output signal V through feedback resistance 2 back to the input of amplifier 4.
  • This input is also connected via a noise filter 8, comprising an input resistance 1, to the Wheatstone bridge 9 which delivers an output voltage V b towards the amplifier.
  • the Wheatstone bridge comprises the wire 15 made of shape memory alloy of which the extremities are connected to terminals 19 and forming a first arm of the bridge.
  • An adjacent arm comprises preferably, but not necessarily, a monitor wire 16 of the same alloy and same dimensions, exposed to the same ambient temperature variations as wire 15, but not exposed to the same overheating risks.
  • the two other arms are formed by two equal resistances 17 and 18.
  • a d.c.-supply voltage is applied between resistances 17 and 18, whereas the point between resistances 15 and 16 is connected to earth. This produces at the output of the bridge an imbalance voltage Y b .
  • the output of the operational amplifier 4 is connected, via noise filter 10, to a second operational amplifier 12.
  • the positive input terminal of this amplifier is connected to the output of amplifier 4 and receives the output voltage V o of the latter, whereas the negative terminal is connected to a potentiometer circuit 11 for adjusting the positive threshold voltage V t .
  • the output of amplifier 12 is connected to a polarized relay 13 which closes contact 14 when the input voltage of amplifier 12 is positive, i.e. when V 0 is larger than V t .
  • the clock-pulse generator 5 of the feedback circuit of the first amplifier 4 delivers pulses every At seconds, e.g. every 15 seconds.
  • the output of this generator is connected to a first input 22 of the up-down counter 6 whereas the other input 23 of this counter is connected to the output of amplifier 4.
  • the counter 6 is so arranged as to count up when the voltage V o at input 23 is positive and down when that voltage is negative.
  • the outputs 24 of the different binary stages of the counter are connected to the input of the digital-to analog converter 7, which is arranged to produce an output voltage V f ' which is proportional to, but has the inverse sign of the digital content of counter 6.
  • the resulting output voltage wave form 26 is a cumulation of voltage step functions of unitary voltage value ⁇ V f , i.e. the amount that the output voltage V f of the converter 7 rises with each decrease of input value of one binary unit.
  • the output voltage V o will be zero, and relay contact 14 remains in the open position shown in the drawing. If not zero in fact, but for instance positive, the counter 6 will accept the clock pulses and increase its binary content in response to which the converter 7 will stepwise lower its output voltage V f , whereby, via feedback resistance 2, the input voltage of amplifier 4 comes down until output voltage V o becomes zero.
  • a circuit responsive to a rate of resistance drop above a threshold value need not necessarily be designed in the form of an operational amplifier with an integrator with limited integrating speed in the feedback circuit. It is also possible to design such circuit in the form of a differentiator, e.g. an operational amplifier with capacitive input impedance and resistive feedback, the output of the differentiator being connected to one input of a threshold circuit, which is adapted to deliver an output signal when the input voltage at that input exceeds a preset voltage, applied at a second input of said threshold circuit.
  • a differentiator e.g. an operational amplifier with capacitive input impedance and resistive feedback
  • the input voltage V b for the operational amplifier need not necessarily be taken from a Wheatstone bridge circuit.
  • the simplest way is to feed with d.c. voltage a series connection of the alloy wire and another resistance, and take the input voltage V b over the extremities of the wire.
  • other passive networks may be used, supplied with a supply voltage, where the voltage V b is taken from two points in the network, adapted to deliver a voltage V b changing in response to the resistance change of said wire, such as across the diagonal points of a Wheatstone bridge. This is consequently meant by "coupling" the wire to the input of the circuit.
  • a fire-alarm system can be designed, in which a round wire 15 is used of 7.6 m length and 2 mm diameter of an alloy 1287 (71.2 % Cu ; 23.6 % Zn ; 4.6 % Al and 0.4 % Co) ; the resistance 15 falls from about 260 milli-ohms to about 225 milli-ohms between about 60°C and about 90°C.
  • the bridge is supplied with a voltage of 1.5 volts and resistances 17 and 18 are of 10 Ohms each, then the total voltage deviation ⁇ V b of the bridge, when only one tenth is heated, is of the order of 0.525 millivolts.
  • each step AV f of the digital-to-analog converter is of the order of 0.05 millivolts
  • the frequency of the clock-pulse generator can be set at about one pulse per 12 seconds. It is however clear that other circuit constants can be taken, which will need other presettings.

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  • Business, Economics & Management (AREA)
  • Emergency Management (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Fire-Detection Mechanisms (AREA)
  • Measuring Temperature Or Quantity Of Heat (AREA)
  • Fire Alarms (AREA)
EP84200654A 1983-05-10 1984-05-08 Dispositif de contrôle de température Ceased EP0128601A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB838312831A GB8312831D0 (en) 1983-05-10 1983-05-10 Temperature monitoring device
GB8312831 1983-05-10

Publications (1)

Publication Number Publication Date
EP0128601A1 true EP0128601A1 (fr) 1984-12-19

Family

ID=10542480

Family Applications (1)

Application Number Title Priority Date Filing Date
EP84200654A Ceased EP0128601A1 (fr) 1983-05-10 1984-05-08 Dispositif de contrôle de température

Country Status (3)

Country Link
EP (1) EP0128601A1 (fr)
JP (1) JPS6041196A (fr)
GB (1) GB8312831D0 (fr)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2598239A1 (fr) * 1986-05-01 1987-11-06 Gen Electric Dispositif de detection de chaleur et/ou de fumee
US4707686A (en) * 1986-04-03 1987-11-17 General Electric Company Over temperature sensing system for power cables
GB2205427A (en) * 1987-06-03 1988-12-07 Simon Peter Fisher Pipe freeze alarm
EP0364298A2 (fr) * 1988-10-13 1990-04-18 Joseph Ralph Beatty Dispositif et procédé de détection de chaleur
FR2650670A1 (fr) * 1989-08-02 1991-02-08 Fiori Costantino Systeme de detection d'incendie ou de tout autre phenomene engendrant une elevation ou une baisse anormale de temperature par rapport a une reference fixee
US5134248A (en) * 1990-08-15 1992-07-28 Advanced Temperature Devices, Inc. Thin film flexible electrical connector
US20080278030A1 (en) * 2007-05-07 2008-11-13 Konica Minolta Opto, Inc. Drive unit and drive module

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP6169121B2 (ja) * 2015-04-13 2017-07-26 株式会社古河テクノマテリアル センサ、リチウムイオン電池の異常検知方法

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1230121A (fr) * 1958-06-21 1960-09-13 Détecteur de début d'incendie
US3044050A (en) * 1959-08-17 1962-07-10 Mc Graw Edison Co Fire detection system
US3516082A (en) * 1967-06-09 1970-06-02 Roy G Cooper Temperature sensing devices
US3643245A (en) * 1970-03-11 1972-02-15 Kidde & Co Walter Discrete heat-detecting system using a thermistor detecting element
GB1589870A (en) * 1977-10-26 1981-05-20 Emi Ltd Fire detector circuit
US4356478A (en) * 1979-05-21 1982-10-26 Cerberus Ag Employing a shape memory alloy in a fire alarm temperature sensitive element

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1230121A (fr) * 1958-06-21 1960-09-13 Détecteur de début d'incendie
US3044050A (en) * 1959-08-17 1962-07-10 Mc Graw Edison Co Fire detection system
US3516082A (en) * 1967-06-09 1970-06-02 Roy G Cooper Temperature sensing devices
US3643245A (en) * 1970-03-11 1972-02-15 Kidde & Co Walter Discrete heat-detecting system using a thermistor detecting element
GB1589870A (en) * 1977-10-26 1981-05-20 Emi Ltd Fire detector circuit
US4356478A (en) * 1979-05-21 1982-10-26 Cerberus Ag Employing a shape memory alloy in a fire alarm temperature sensitive element

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4707686A (en) * 1986-04-03 1987-11-17 General Electric Company Over temperature sensing system for power cables
FR2598239A1 (fr) * 1986-05-01 1987-11-06 Gen Electric Dispositif de detection de chaleur et/ou de fumee
GB2205427A (en) * 1987-06-03 1988-12-07 Simon Peter Fisher Pipe freeze alarm
EP0364298A2 (fr) * 1988-10-13 1990-04-18 Joseph Ralph Beatty Dispositif et procédé de détection de chaleur
EP0364298A3 (fr) * 1988-10-13 1990-12-19 Joseph Ralph Beatty Dispositif et procédé de détection de chaleur
FR2650670A1 (fr) * 1989-08-02 1991-02-08 Fiori Costantino Systeme de detection d'incendie ou de tout autre phenomene engendrant une elevation ou une baisse anormale de temperature par rapport a une reference fixee
US5134248A (en) * 1990-08-15 1992-07-28 Advanced Temperature Devices, Inc. Thin film flexible electrical connector
US20080278030A1 (en) * 2007-05-07 2008-11-13 Konica Minolta Opto, Inc. Drive unit and drive module
US8174608B2 (en) * 2007-05-07 2012-05-08 Konica Minolta Opto, Inc. Drive unit and drive module

Also Published As

Publication number Publication date
GB8312831D0 (en) 1983-06-15
JPS6041196A (ja) 1985-03-04

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Inventor name: VANDORPE, JOHN