WO1983000574A1 - Dispositif de commande ou de detection de temperature - Google Patents

Dispositif de commande ou de detection de temperature Download PDF

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Publication number
WO1983000574A1
WO1983000574A1 PCT/GB1982/000240 GB8200240W WO8300574A1 WO 1983000574 A1 WO1983000574 A1 WO 1983000574A1 GB 8200240 W GB8200240 W GB 8200240W WO 8300574 A1 WO8300574 A1 WO 8300574A1
Authority
WO
WIPO (PCT)
Prior art keywords
temperature
circuit
bridge
link
resistance
Prior art date
Application number
PCT/GB1982/000240
Other languages
English (en)
Inventor
First International Limited Service
Original Assignee
Wright, Archibald, Robert
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 Wright, Archibald, Robert filed Critical Wright, Archibald, Robert
Priority to AU87663/82A priority Critical patent/AU8766382A/en
Publication of WO1983000574A1 publication Critical patent/WO1983000574A1/fr

Links

Classifications

    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
    • G05D23/00—Control of temperature
    • G05D23/19—Control of temperature characterised by the use of electric means
    • G05D23/20—Control of temperature characterised by the use of electric means with sensing elements having variation of electric or magnetic properties with change of temperature
    • G05D23/24—Control of temperature characterised by the use of electric means with sensing elements having variation of electric or magnetic properties with change of temperature the sensing element having a resistance varying with temperature, e.g. a thermistor
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
    • G05D23/00—Control of temperature
    • G05D23/19—Control of temperature characterised by the use of electric means
    • G05D23/1902—Control of temperature characterised by the use of electric means characterised by the use of a variable reference value

Definitions

  • TITLE - Temperature controlling or detecting device
  • This invention relates to a temperature controlling or detecting device, and in particular to a temperature controlling device (hereinafter referred to as a thermostat) .
  • thermostats generally rely on __ physical movement of adjacent components to cause a switching action at a desired temperature.
  • Such components may include bimetallic strips, or bellows actuated by liquid expansion, which inturn act on a mechanical switch.
  • Such conventional thermostats have a number of disadvantages. For one thing, they are inclined to be inaccurate. Furthermore, 'it is easy for an unauthorized person to alter the temperature at which the switching action mentioned above takes place. This is of particular significance in offices, factories, warehouses and other industrial and commercial premises, where it may be not only advisable to avoid excessive expenditure on heating, but where legally specified maximum temperatures may be exceeded, with a consequent risk of prosecution.
  • a temperature controlling or detecting device having a circuit which cor.prises a temperature-sensitive element whose electrical resistance changes with temperature and means for detecting changes in the resistance of the said element and producing an output signal at a predetermined temperature or at the upper and lower limits of a predetermined temperature range in res ⁇ ponse thereto, and means for encapsulating at least a sufficient part of the circuit to prevent ready adjustment of the said predetermined temperature or temperature range.
  • Figure 1 shows a circuit for use in the thermostat according to the invention
  • Figure 2 is a general view of the thermostat.
  • the illustrated circuit comprises a sensor 1 which is a temperature-sensitive silicon chip, for example that available from Texas Instruments under the code TSF 102G. This has a resistance of approximately 900 ohms at 20°C and a sensitivity of +7.1 ohms per °C.
  • the sensor is positioned in one side of a Wheatstone bridge.
  • the arm which contains the sensor 1 also contains a resistor 2 which is normally short-circuited by a link 3. The purpose of this will become apparent from the ensuing description.
  • Two of the remaining sides of the bridge have resistors 4 and 5 respectively, the resistances of those resistors being equal to one another.
  • the fourth side of the bridge cont- ains a series combination of a resistor 7, an adjustable resistor 8, a resistor 9, and a further resistor 10 which is normally short-circuited by a link 11.
  • Power is supplied to terminals 12 and 13 of the bridge from a five volt DC stabilized supply 14.
  • An operational amplifier 15 is connected between the terminals 16 and 17 of the bridge and acts as a voltage comparator.
  • V the voltage at terminal 16
  • V the voltage at terminal 17
  • the voltage transition at Vc is used to control a relay 21 or an equivalent electronic component, for example a triac or thyristor. Control is effected through a buffer switch 22, which is in the form of a power FET of VM0S type or a transistor, or a second comparator. If the ambient temperature is lower than that at which the bridge is balanced the relay will be energised, but as the temp ⁇ erature passes through that at which balance is achieved the relay will de-energise. Thus, if the bridge is balanced at a temperature N°C the relay will be energised (i.e. its contacts will be closed) at temperatures below N°C and de-energised (i.e. its contacts will be open) at temperatures above N°C. Thus, the relay 21 can be used to control a heating, cooling, ventilating or air- conditioning system so as to maintain the temperature of the space in which the thermostat is located substantially constant. The relay, or its equivalent, may be remote from the thermostat.
  • the resistors 2 and 10 are normally short-circuited by links 3 and 11. These links are made so as to be severable, and provide a means of adjusting the temperature at which the bridge balances. For example, if the resistor 2 has a resistance of 7.1 ohms (the temperature sensitivity of the sensor 1) cutting links 3 will cause the thermostat to operate one degree lower than previously. Similarly, cutting link 11 will cause the thermostat to operate one degree higher .
  • resistor 10 and link 11 could be positioned in series with resistor 2 and link 3. If, then, resistor 10 has a value of 14.2 ohms, cutting link 3 would cause the thermostat to operate 1°C lower, cutting link 11 will cause it to operate 2 °C lower, and cutting both will cause it to operate 3°C lower.
  • FIG. 2 shows, partly in cross-section and partly in side view, an embodiment of the thermostat according to the invention.
  • the illustrated embodiment comprises a housing 50 having an open front which is covered by a heat-conducting metal front plate 51.
  • the plate 51 is spaced from the casing 50 by two insulating gaskets 52.
  • An inner housing 53 is mounted inside the assembly of housing 50 and plate 51 through heat-insulating gaskets 54 by means of which it is secured to the front plate 51 with a gap therebetween.
  • one side wall of the inner housing 53 has been partly cut away to show a circuit board 55 on which is mounted the circuit of Figure 1.
  • the circuit board 55 carries the necessary circuit components on the side thereof remote from the front plate 51, with the conduct ⁇ ors being located on the side adjacent the front plate 51.
  • the interior of the inner housing 53 is largely filled with a thermosetting, electrically insulating resin 57.
  • This resin prevents access being obtained to the circuit board 55 after the circuit board has been installed.
  • the links 3 and 11 protrude out of the surface of the resin 57, so that these links can be severed if it is desired to alter the temperature response of the thermostat.
  • the same circuit can be used, if desired, as a fire detector.
  • a plurality of devices of the type described above can be connected in series or in parallel to a suitable monitoring system which would detect any anomalous temperature increases, for example such increases caused by fire.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Automation & Control Theory (AREA)
  • Thermally Actuated Switches (AREA)

Abstract

Un dispositif de commande ou de détection de température possède un circuit qui comprend un élément thermo-sensible (1) dont la résistance électrique varie avec la température. Les variations de la résistance de cet élément (1) sont détectées par un dispositif comprenant un pont de Wheatstone et un amplificateur opérationnel (15). L'amplificateur (15) produit un signal de sortie à une température prédéterminée ou aux limites supérieure et inférieure d'une gamme de températures prédéterminées en réponse aux variations de la résistance de l'élément (1). Au moins une partie suffisante du circuit est encapsulée dans une résine pour empêcher un ajustement rapide de la température prédéterminée ou de la gamme de températures.
PCT/GB1982/000240 1981-08-05 1982-08-04 Dispositif de commande ou de detection de temperature WO1983000574A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU87663/82A AU8766382A (en) 1981-08-05 1982-08-04 Temperature controlling or detecting device

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB8123950810805 1981-08-05
GB8123950 1981-08-05

Publications (1)

Publication Number Publication Date
WO1983000574A1 true WO1983000574A1 (fr) 1983-02-17

Family

ID=10523718

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1982/000240 WO1983000574A1 (fr) 1981-08-05 1982-08-04 Dispositif de commande ou de detection de temperature

Country Status (2)

Country Link
EP (1) EP0085077A1 (fr)
WO (1) WO1983000574A1 (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0383718A2 (fr) * 1989-02-17 1990-08-22 Emerson Electric Co. Contrôle d'un élément de chauffage
US5128516A (en) * 1989-02-17 1992-07-07 Therm-O-Disc, Incorporated Heating element control
US5653756A (en) * 1990-10-31 1997-08-05 Baxter International Inc. Closed porous chambers for implanting tissue in a host
US5851230A (en) * 1994-08-12 1998-12-22 Meadox Medicals, Inc. Vascular graft with a heparin-containing collagen sealant

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1064002A (en) * 1964-02-25 1967-04-05 Robertshaw Controls Co Electro-pneumatic temperature controlling systems
US3581062A (en) * 1968-02-19 1971-05-25 Pavelle Corp Electronic thermostat
DE2263018A1 (de) * 1972-12-22 1974-07-04 Siemens Ag Schaltung zur temperaturregelung wechselstrombeheizter werkzeuge
US4085310A (en) * 1975-03-26 1978-04-18 U.S. Philips Corporation Control device for electric heating systems of the bi-junction type for an apartment building
US4160897A (en) * 1977-06-14 1979-07-10 Ngk Spark Plug Co., Ltd. Ceramic heating element with restivity adjusted to a certain value

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1064002A (en) * 1964-02-25 1967-04-05 Robertshaw Controls Co Electro-pneumatic temperature controlling systems
US3581062A (en) * 1968-02-19 1971-05-25 Pavelle Corp Electronic thermostat
DE2263018A1 (de) * 1972-12-22 1974-07-04 Siemens Ag Schaltung zur temperaturregelung wechselstrombeheizter werkzeuge
US4085310A (en) * 1975-03-26 1978-04-18 U.S. Philips Corporation Control device for electric heating systems of the bi-junction type for an apartment building
US4160897A (en) * 1977-06-14 1979-07-10 Ngk Spark Plug Co., Ltd. Ceramic heating element with restivity adjusted to a certain value

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0383718A2 (fr) * 1989-02-17 1990-08-22 Emerson Electric Co. Contrôle d'un élément de chauffage
EP0383718A3 (fr) * 1989-02-17 1991-11-27 Emerson Electric Co. Contrôle d'un élément de chauffage
US5128516A (en) * 1989-02-17 1992-07-07 Therm-O-Disc, Incorporated Heating element control
US5653756A (en) * 1990-10-31 1997-08-05 Baxter International Inc. Closed porous chambers for implanting tissue in a host
US5851230A (en) * 1994-08-12 1998-12-22 Meadox Medicals, Inc. Vascular graft with a heparin-containing collagen sealant
US6162247A (en) * 1994-08-12 2000-12-19 Meadox Medicals, Inc. Vascular graft impregnated with a heparin-containing collagen sealant

Also Published As

Publication number Publication date
EP0085077A1 (fr) 1983-08-10

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