US3920956A - Temperature control apparatus - Google Patents

Temperature control apparatus Download PDF

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Publication number
US3920956A
US3920956A US478093A US47809374A US3920956A US 3920956 A US3920956 A US 3920956A US 478093 A US478093 A US 478093A US 47809374 A US47809374 A US 47809374A US 3920956 A US3920956 A US 3920956A
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United States
Prior art keywords
core
temperature
winding
thyristor
temperature control
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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.)
Expired - Lifetime
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US478093A
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English (en)
Inventor
Masanori Endo
Ken Miyagi
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Tokin Corp
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Tohoku Metal Industries Ltd
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Publication date
Priority claimed from JP6782173U external-priority patent/JPS5016410U/ja
Priority claimed from JP1973067820U external-priority patent/JPS5521129Y2/ja
Priority claimed from JP11574273A external-priority patent/JPS5515728B2/ja
Application filed by Tohoku Metal Industries Ltd filed Critical Tohoku Metal Industries Ltd
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Publication of US3920956A publication Critical patent/US3920956A/en
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    • 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
    • G05D23/26—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 permeability varying with temperature
    • 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
    • G05D23/1906—Control of temperature characterised by the use of electric means using an analogue comparing device

Definitions

  • thermo-detector means thermo-coupled with the heater means to turn on and off the switching means below and above a predetermined temperature, in which a thyristor is employed for the switching means, the thermo-detector means being a transformer which has a primary winding connected to the power source through a resistor means, a secondary winding connected to the control terminal of the thyristor and a core of magnetic materials having a Curie point of the predetermined temperature, a low coercive force and a high differential permeability at a magnetic field strength equal to the coercive force.
  • Outputs on the transformer secondary winding fire the thyristor at each zero voltage of the AC voltage to permit the heater means to be excited below the predetermined temperature. No output is present on the secondary winding above the predetermined temperature so that the thyristor is not fired.
  • An inductor having a winding and a core of similar magnetic materials as above may be substituted for the transformer to perform the same purpose, in which case the self-induced voltage on the inductor winding is coupled to the control terminal of the thyristor.
  • a temperature operated switch consisting of a reed switch, permanent magnets and temperature sensitive magnetic materials having a Curie point of a predetermined temperature, has been used to sense a temperature and to control the power supply to a heater means.
  • the operation of the heater means can be initiated when the temperature of the magnetic materials becomes below the Curie point, and it can be stopped when the temperature becomes above the Curie point.
  • temperature control using such a temperature operated switch encounters difficulty caused by disadvantages of theswitch, that is, the wear of contacts of the switch, a short life time of the switch and the resultant reduction in reliability.
  • Another known apparatus employs a transformer comprising a primary winding, a secondary winding and a core having a Curie point of a predetermined temperature with AC power being supplied to the primary winding and with a heater means being connected to the secondary winding. At a temperature above the Curie point, the voltage induced from primary winding to the secondary winding is reduced so that the operation of the heater means may be stopped.
  • the apparatus requires theuse of a transformer of a great volume to obtain high calorie or energy transfer and has, therefore, an inferior temperature response. Furthermore, the known apparatus cannot achieve start and stop of the excitation of the heater means from zero' voltage portions of: the AC voltage from the power source.
  • a 'thyristor such as an SCR or a Triac is connected between a heater element and an AC power source, a transformer having a core of the Curie point of a prede- -.termined temperature being provided, a primary winding being supplied with an input pulse train, and a secondary winding being coupled to a control terminal.
  • a pulse generator is required to obtain the pulse train, which complicates electric circuit of the apparatus.
  • Another object of this invention is to provide a temperature control apparatus having a long life time and high reliability.
  • Still another object of this invention is to realize the above objects by the use of circuitry elements of small volume.
  • Another object of this invention is to provide a temperature control apparatus comprising electric heater means, a thyristor, a transformer and a resistor in which the excitation of the heater means is started from zero voltage portions of 'the AC voltage.
  • Yet another object of this invention is to provide a temperature control apparatus comprising an electric heater means, a thyristor, an inductor and a resistor, in which the excitation of the heater means is started from zero voltage portions of the AC voltage.
  • a further object of this invention is to provide a transformer and an inductor which provide excellent temperature response to realize the above objects.
  • a temperature control apparatus of this invention comprises electric heater means excited by an AC electric power source, a thyristor, such as an SCR, SSS, Triac or the like, connected between the AC electric power source and the electric heater means for switching on or off the power supply to the electric heater means, a resistor, and a transformer which is thermocoupled with the electric heater means, the transformer comprising a primary winding, a secondary winding and a core having a lottery point of a predetermined temperature and a generally rectangular hysteresis loop.
  • the primary winding is connected to the AC electric power source through the resistor and the secondary winding is coupled to the control terminal of the thyristor, whereby the thyristor may be turned on by the impulses present on the secondary winding.
  • Another temperature control apparatus of this invention comprises electric heater means excited by an AC electric power source, a thyristor connected between the AC electric power source and the electric heater means for switching on or off the power supply to the electric heater means, a resistor, and an inductor which is thermo-coupled with the electric heater means, the inductor comprising a winding and a core having a Curie point of a predetermined temperature and a generally rectangular hysteresis loop.
  • the inductor winding is connected to the AC electric power source through the resistor and is coupled to the control terminal of the thyristor, whereby the thyristor may be turned on by the impulses self-induced on the winding.
  • the core of the transformer or the inductor used in the apparatus of this invention ismade of magnetic materials having properties of a less coercive forceiand a high differential permeability at a magnetic field strength equal to the coercive force, besides the above described properties.
  • FIG. 1a shows a circuit diagram of an embodiment of this invention
  • FIG. 1b graphically illustrates the hysteresis loop of the core of the transformer in FIG. la
  • FIG. 10 graphically illustrates the temperature response of the differential permeability at the coercive force of the core of the transformer in FIG. la,
  • FIG. 1d schematically illustrates voltage and current waveforms at various points in the circuit in FIG. 1a, when the heater is excited
  • FIG. 1e schematically illustrates voltage and current waveforms at various points in the circuit in FIG. la, when the excitation of the heater is stopped,
  • FIG. 2 shows a circuit diagram of another embodiment of this invention
  • FIG. 3a shows a circuit diagram of still another embodiment of this invention
  • FIG. 3b graphically illustrates a temperature control of the voltage input to the gate of the thyristor in FIG.
  • FIGS.-4 and 5 show circuit diagrams of further embodiments of this invention.
  • FIG. 6 shows a sectional view of an embodiment of a core of the transformer or the inductor used in an apparatus of this invention.
  • an embodiment of this invention comprises an electric heater element 2 and a Triac 3 connected in series to an AC electric power source 1.
  • a primary winding 7 of a transformer S is connected to the'AC electric power source through a resistor 4 and a secondary winding 8 of the transformer 5 is coupled to the gate of the Triac 3.
  • the transformer 5 is contained and positioned in an oven 9 in which the heater 2 is mounted so that the transformer is exposed to the temperature in the oven.
  • the core 6 of the transformer 5 is of a magnetic material, the Curie point of which corresponds to the temperature in the oven 9 to be maintained.
  • the Core 6 exhibits a generally rectangular hysteresis loop with a less coercive force as shown in FIG. 1b and such a temperature response of the differential permeability miif at a magnetic field strength equal to the coercive force as shown in FIG. 1c in which the differential permeability udif gradually decrease slightly by elevation of the temperature and is rapidly reduced close to the Curie point Tc. Accordingly, the core 6 has ferr'o-magnetic properties below the Curie point and exhibits paramagnetism at and above the Curie point.
  • FIGS. 1b and 1c Examples of magnetic. materials exhibiting magnetic properties illustrated in FIGS. 1b and 1c and above described, are:
  • Example A magnetic material comprising Fe O 50.6-54.8 mol MnO 6.420.4 mol ZnO 43.0-24.8 mol and addition if necessary. Curie point: from 30 to 150C.
  • Example B magnetic material comprising Fe O 50.0 mol ZnO 33.0-38.0 mol NiO 12.0-17.0 mol and, if necessary, additions Curie point: from 0 to 120C
  • Example C magnetic material comprising Ni 78-80 mol Nb, Cu, Mo and Fe Curie point: 395C I
  • an Ac current i flows through the resistor 4 and the primary winding 7 from the AC electric power source, the AC voltage v of which exhibits, for example, a sine-curved waveform as shown at (l) in FIG. 1d.
  • the core 6 has ferromagnetic properties as shown in FIG. 1b, so that the AC magnetic flux flows through the core 6. The.
  • waveform of the AC magnetic flux is a generally square waveform as shown at (3) in FIG. 1d because the core has a rectangular hysteresis loop with a less coercive force. Accordingly animpulsle is induced and is present on the secondary winding 8 at each time when the AC voltage is zero voltage, with two successive impulses being of reverse polarity in correspondence with the AC voltage, as shown (4) inFIG. 1d.
  • the impulses v present on the secondary winding 8 are coupled to the gate of the Triac 3 to fire the Triac at each time when the AC voltage v is zero voltage to permit a current to flow through the Triac 3.
  • the AC current i flows through the heater element 2, which is, in turn, excited to elevate the inner temperature of the oven 9.
  • the inner temperature of the oven 9 is controlled to be substantially constant.
  • the excitation of the heater element 2 is started and stopped at the zero voltage of the AC voltage from the AC electric power source, because the Triac 3 connected between the heater element 2 and the power source is controlled in its turning on and off operation by impulses presented at every time when the AC voltage, is at its zero voltage level. Accordingly, the electric power is efficiently used without power loss.
  • the temperature control apparatus of this embodiment is simple, has a long life and has high reliability, because it consists of merely a heater element, a Triac, a transformer and a resistor.
  • FIG. 2 another embodiment of this invention shown in FIG. 2 is similar to the embodiment shown in FIG. 1a, except that an SCR is substituted for the Triac 3 with a diode 11 being connected in parallel with and in reverse polarity with the SCR. Similar parts are denoted by same numerals in FIG. 1a.
  • the inner temperature of the oven 9 is prevented from rapidly dropping from the temperature above the Curie point of the core 6 so that the damage of the oven and various parts in the oven due to the rapid temperature variation may be prevented. Furthermore the temperature control is performed smoothly and the ripple of the temperature is reduced.
  • the heater element 2 is not excited when the inner temperature of the oven 9 is at or above the Curie point of the core 6. But when the inner temperature of the oven 9 is below the Curie point of the core 6, impulses present on the secondary winding 8 fire the SCR 10 at every one period internal of the AC voltage, to permit the Current to flow through the heater element 2 during half periods when the AC voltage is applied to the SCR in the forward direction thereof. Accordingly, the apparatus having a circuit formation wherein the diode 11 of the embodiment in FIG. 2 is omitted can, also, perform temperature control.
  • FIG. 3a shows a circuit diagram of another embodiment which is 'a modification of the embodiment in FIG. 1a.
  • This embodiment is different from the embodiment in FIG. 1a, merely in that the voltage on the secondary winding 8 of the transformer 5 is supplied through the voltage divider or the potentiometer comprising a variable resistor 12 and a fixed resistor 13.
  • impulses Vp are induced to the secondary winding 8, as shown at (4) in FIG. 1d.
  • the impulses are voltage divided at the potentiometer before it is applied to the gate of the Triac 3.
  • thevoltage applied to the gate of the Triac 3 is controlled by regulating the variable resistor 12.
  • the voltage applied to the gate changes by elevation of the temperature of the core 6 as shown in FIG. 3b, in which the curve a shows the variation of the gate voltage when the resistance of the variable resistor 12 is minimum, the curve b showing the variation of the gate voltage at a maximum resistance of the resistor 12.
  • this embodiment has an advantage that the inner temperature of the oven 9 to be kept constant can be var- 6 ied only by regulating the resistance of the variable resistor in the potentiometer.
  • FIG. 4 Another embodiment of this invention shown in FIG. 4 is similar as the embodiment shown in FIG. la except that the series circuit including the resistor 4 and the primary winding 7 is connected to the power source 1 through the heating element 2 so that the heater element 2 is applied the AC current through the series circuit even if the inner temperature of the oven 9 is at or above the Curie point of the core 6.
  • FIG. 5 shows an embodiment in which an inductor 14 is used in place of the transformer 5 in the above embodiments.
  • the inductor 14 comprises a winding 15 and a core 16 which has similar magnetic properties as the core 6 of the transformer 5 used in the above embodiments.
  • the winding 15 is connected to the AC power source 1 through the series resistor 4 and, also, is connected to the gate of the Triac 3.
  • impulses self-induced on the winding 15 are utilized to fire the Triac 3.
  • This embodiment has an avdvantage that the simplification of the circuitry is realized more than the apparatus using a transfomer because the secondary winding is not necessary.
  • the core used in the transformer or the inductor in this invention may have, of course, any usual construction known in the prior art.
  • FIG. 6 shows a preferably construction of the core, in which the core comprising a U-shape magnetic piece 61 and a bar-type magnetic piece 62, both being connected and fixed to each other in such fashion that a circular closed loop of magnetic flux path may be formed.
  • the bar-type magnetic piece 62 is of the magnetic material having the Curie point equal to the temperature to be maintained in the temperature control apparatus, while the U-shaped piece 61 is of the magnetic material having the Curie point-higher than the Curie point of the bar-type magnetic piece 62.
  • a winding or windings are mounted on the U-shape piece 62 as shown by dotted lines in FIG. 6.
  • the bar-type piece 62 serves as a sensor of the temperature, so that temperature control with excellent temperature response may be performed because the sensor is small in volume and, therefore, in heat capacity.
  • the .controlled temperature may be easily changed only by replacing the bar-type magnetic piece 62 by one having a different Curie point.
  • a temperature control apparatus comprising:
  • a thyristor connected between said AC electric power source and said electric heater means for switching on or off the power supply to said electric heater means
  • thermo-coupled with said electric heater means said transformer comprising:
  • a core on which said windings are wound said core having a Curie point of a predetermined temperature, and said core having a generally rectangular hysteresis loop with a less coercive force and a high differential permeability at the magnetic field strength equal to the coercive force, whereby when said core is at temperatures below said predetermined temperature an impulse signal is present on said secondary winding at each zero voltage point of the AC power signal and when said coreis at a temperature at or above said predetermined temperature no output is present on said secondary winding,
  • the core of said transformer is of one selected from the group of an alloy comprising 78-80 Ni, Nb, Cu, Mo and Fe, an alloy comprising 50.6-54.8 mol Fe O 6.420.4 mol MnO v24.8-43.0 mol ZnO and additions, and an alloy comprising l2.0-l7.0 mol NiO, 33.038.0 mol ZnO, 50.0 mol Fe O and additions.
  • the core of said transformer comprises a bar-type magnetic piece having a Curie point of said predetermined temperature, and a generally V- shaped magnetic piece having a Curie point higher than the Curie point of said bar-type magnetic piece, both of said magnetic pieces being connected and fixed to each other such that a circular closed magnetic flux loop may be formed, and said windings of said transformer are mounted on said generally U-shaped magnetic piece.
  • thermocontrol device as claimed in claim 1, in which said thyristor is an SCR, and further including a rectifying diode connected in parallel with, and in the reverse direction of, said SCR.
  • a temperature control apparatus comprising:
  • a thyristor connected between said AC electric power source and said electric heater means for switching on or off the power supply to said electric heater means
  • thermo-coupled with said electric heater means said inductor comprising:
  • a core on which said winding is wound said core having a Curie point of a predetermined temperature, and said core having a generally rectangu lar hystersis loop with a less coercive force and a high differential permeability at the magnetic field strength equal to the coercive force, whereby when said core is at temperatures below said predetermined temperature a self-induced impulse signal is present on said winding at each zero voltage point of the AC power signal and when said core is at a temperature at or above said predetermined temperature no output is present on said winding,
  • said thyristor being turned on by the impulse present on said winding when the temperature of said core is below said predetermined temperature to couple the AC electric power to said electric heater to energize' said electric heater, said thyristor. being maintained in its off condition when said temperature of said core is at or above said predetermined temperature.
  • the core of said inductor is of one selected from the group of an alloy comprising 78-80 Ni, Nb, Cu, Mo and Fe, an alloy comprising 50.6-54.8 mol Fe O 6.4-20.4 mol MnO 24.8-43.0 mol ZnO and additions, and an alloy comprising 12.0-17.0 mol NiO, 33.0-38.0 mol ZnO, 50.0 mol Fe O and additions.
  • the core of said inductor comprises a bar-type magnetic piece having a Curie point of said predetermined temperature, and a generally U-shaped magnetic piece having a Curie point higher than the Curie point of said bar-type magnetic piece, both of said magnetic pieces being connected and fixed to each other such that a circular closed magnetic flux loop may be formed, and said winding of said inductor is mounted on said generally U-shaped magnetic piece.
  • thermocontrol device as claimed in claim 8, in which said thyristor is an SCR, and further including a rectifying diode connected in parallel with, and in the reverse direction of, said SCR.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Automation & Control Theory (AREA)
  • Control Of Temperature (AREA)
  • Control Of Resistance Heating (AREA)
US478093A 1973-06-11 1974-06-10 Temperature control apparatus Expired - Lifetime US3920956A (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
JP6782173U JPS5016410U (enrdf_load_stackoverflow) 1973-06-11 1973-06-11
JP1973067820U JPS5521129Y2 (enrdf_load_stackoverflow) 1973-06-11 1973-06-11
JP11574273A JPS5515728B2 (enrdf_load_stackoverflow) 1973-10-17 1973-10-17

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US3920956A true US3920956A (en) 1975-11-18

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US478093A Expired - Lifetime US3920956A (en) 1973-06-11 1974-06-10 Temperature control apparatus

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US (1) US3920956A (enrdf_load_stackoverflow)
DE (1) DE2427961C3 (enrdf_load_stackoverflow)
FR (1) FR2232794B1 (enrdf_load_stackoverflow)
IT (1) IT1014964B (enrdf_load_stackoverflow)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5403992A (en) * 1992-04-11 1995-04-04 Imetec S.P.A. Electrically heated panels
US5453598A (en) * 1990-09-28 1995-09-26 The Balance Dynamics Corporation Apparatus for the transfer of electrical power to a balancer
US6043465A (en) * 1998-06-12 2000-03-28 Thermal Technology, Inc. Temperature measurement device for furnace heating elements, furnace utilizing said device and method of using the same
US6180928B1 (en) * 1998-04-07 2001-01-30 The Boeing Company Rare earth metal switched magnetic devices
FR2816461A1 (fr) * 2000-11-09 2002-05-10 Bosch Gmbh Robert Machine electrique notamment alternateur
US6544937B2 (en) 2001-05-22 2003-04-08 Exxonmobile Research And Engineering Company Demulsification of industrial lubricants containing naphthenic basestocks
US20090250440A1 (en) * 2008-04-04 2009-10-08 Yap Tze-Yee Ryan Out-of-phase electrical welder and process
US20090281669A1 (en) * 1999-03-31 2009-11-12 Lord Corporation Method and apparatus for balancing
CN112062464A (zh) * 2020-08-27 2020-12-11 李悌坚 一种节能光学玻璃成型模具及辅助推出装置

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3113545A1 (de) * 1981-04-03 1982-10-21 Siemens AG, 1000 Berlin und 8000 München Sicherheitsthermostat fuer heizer
RU2115895C1 (ru) * 1997-02-18 1998-07-20 Сергей Алексеевич Гулин Магнитоконтактный термодатчик

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3328561A (en) * 1963-05-07 1967-06-27 Matsushita Electric Ind Co Ltd Electric cooking apparatus having thermomagnetic temperature control means
US3369108A (en) * 1965-05-11 1968-02-13 Texas Instruments Inc Temperature controller
US3427436A (en) * 1966-05-10 1969-02-11 Texas Instruments Inc Temperature controller
US3569673A (en) * 1969-03-03 1971-03-09 Texas Instruments Inc Temperature control and indicating system

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3328561A (en) * 1963-05-07 1967-06-27 Matsushita Electric Ind Co Ltd Electric cooking apparatus having thermomagnetic temperature control means
US3369108A (en) * 1965-05-11 1968-02-13 Texas Instruments Inc Temperature controller
US3427436A (en) * 1966-05-10 1969-02-11 Texas Instruments Inc Temperature controller
US3569673A (en) * 1969-03-03 1971-03-09 Texas Instruments Inc Temperature control and indicating system

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5453598A (en) * 1990-09-28 1995-09-26 The Balance Dynamics Corporation Apparatus for the transfer of electrical power to a balancer
US5403992A (en) * 1992-04-11 1995-04-04 Imetec S.P.A. Electrically heated panels
US6467326B1 (en) 1998-04-07 2002-10-22 The Boeing Company Method of riveting
US6180928B1 (en) * 1998-04-07 2001-01-30 The Boeing Company Rare earth metal switched magnetic devices
US6184503B1 (en) 1998-04-07 2001-02-06 The Boeing Company Riveter
US6043465A (en) * 1998-06-12 2000-03-28 Thermal Technology, Inc. Temperature measurement device for furnace heating elements, furnace utilizing said device and method of using the same
US20090281669A1 (en) * 1999-03-31 2009-11-12 Lord Corporation Method and apparatus for balancing
US8100009B2 (en) 1999-03-31 2012-01-24 Lord Corporation Method and apparatus for balancing
FR2816461A1 (fr) * 2000-11-09 2002-05-10 Bosch Gmbh Robert Machine electrique notamment alternateur
US6544937B2 (en) 2001-05-22 2003-04-08 Exxonmobile Research And Engineering Company Demulsification of industrial lubricants containing naphthenic basestocks
WO2002094968A3 (en) * 2001-05-22 2004-07-08 Exxonmobil Res & Eng Co Demulsification of industrial lubricants containing naphthenic basestocks
US20090250440A1 (en) * 2008-04-04 2009-10-08 Yap Tze-Yee Ryan Out-of-phase electrical welder and process
CN112062464A (zh) * 2020-08-27 2020-12-11 李悌坚 一种节能光学玻璃成型模具及辅助推出装置
CN112062464B (zh) * 2020-08-27 2021-06-04 江西特莱斯光学有限公司 一种节能光学玻璃成型模具装置

Also Published As

Publication number Publication date
FR2232794A1 (enrdf_load_stackoverflow) 1975-01-03
DE2427961C3 (de) 1980-10-30
DE2427961A1 (de) 1975-01-02
IT1014964B (it) 1977-04-30
DE2427961B2 (de) 1980-02-14
FR2232794B1 (enrdf_load_stackoverflow) 1978-07-07

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