US3732394A - Iron - Google Patents

Iron Download PDF

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Publication number
US3732394A
US3732394A US00115979A US3732394DA US3732394A US 3732394 A US3732394 A US 3732394A US 00115979 A US00115979 A US 00115979A US 3732394D A US3732394D A US 3732394DA US 3732394 A US3732394 A US 3732394A
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US
United States
Prior art keywords
capacitor
control circuit
iron
circuit according
switching means
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.)
Expired - Lifetime
Application number
US00115979A
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English (en)
Inventor
M Cusworth
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.)
ISSAAC BRAITHWAITE AND SON ENGIN
Original Assignee
ISSAAC BRAITHWAITE AND SON ENGIN
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.)
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Application filed by ISSAAC BRAITHWAITE AND SON ENGIN filed Critical ISSAAC BRAITHWAITE AND SON ENGIN
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Publication of US3732394A publication Critical patent/US3732394A/en
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Expired - Lifetime legal-status Critical Current

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Classifications

    • D—TEXTILES; PAPER
    • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
    • D06F—LAUNDERING, DRYING, IRONING, PRESSING OR FOLDING TEXTILE ARTICLES
    • D06F75/00—Hand irons
    • D06F75/08—Hand irons internally heated by electricity
    • D06F75/26—Temperature control or indicating arrangements
    • 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
    • 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

Definitions

  • This invention relates to an iron and more particularly to an iron, the temperature of which is controllable.
  • an iron including heating means and sole plate wherein means for controlling the heating means is provided in the sole plate.
  • the means for controlling the heating means comprises a thermistor and the heating means comprises one or more electrical heating elements located in the sole plate.
  • the iron may be of the all electric type or what is termed a steam electric iron in which steam is sprayed from perforations in the sole plate.
  • the circuitry by which the thermistor controls the element may be of any suitable design. It is preferred that the circuitry be designed to maintain the iron at any desired temperature preferably from 90 to 260 C.
  • FIG. 1 is a section through an iron
  • FIG. 2 is a circuit diagram of a preferred control circuit.
  • the iron comprises a sole plate 1 which is preferably made of bronze with a chrome finish, and which is secured to an element plate 2, made for example of aluminum, by studs of which one 9 is shown.
  • a bore 7 is formed through the element plate and a bore 8 is formed in the sole plate such that when the element and sole plates are secured together the bores are co-axial.
  • the bore 8 extends from the face of the sole plate adjacent the element plate to a point close to the face of the sole plate remote from the element plate, but as shown in FIG. 1 does not extend completely through the sole plate.
  • a thermistor holder 10 is provided in the bores 7 and 8 and a thermistor 11 is located in the holder.
  • the thermistor is coupled into a control circuit as shown in FIG. 2 via a terminal 6, the control circuit in the present embodiment being located externally of the iron.
  • the thermistor is an inert or solid state device.
  • a moulded handle and cover-3 which may for example be made of plastics material is secured to the element plate by studs, one of which 12 is shown.
  • An asbestos sheet 13 is interposed between the cover and the element plate.
  • control circuit may be provided within the casing instead of externally thereof.
  • FIG. 2 A suitable control circuit for the iron just described is shown in FIG. 2.
  • the temperature of an iron 15 is controlled by means of a thermistor 16 the thermistor itself being controllable by means of a variable resistance 17
  • the heating element is connected to the current supply by means of switch 18 the iron .will heat up and as it does so the resistance of the thermistor will decrease.
  • This has the effect of reducing the current drawn by the iron heater elements so that the heat of the iron can be limited to a value determined by the variable resistor.
  • the resistance of the thermistor will rise so that the heater elements again draw sufficient current to V heat the iron. It will be appreciated that with this arrangement very close control of iron temperature can be maintained.
  • FIG. 2 shows, power for iron 15 is applied at terminals 20 and 22, and after passing through a short-circuit protection fuse 24, a MAINS ON indication is provided by a neon lamp 26. Surge and radio interference protection is provided by a series choke 28 and a shunt capacitor 30 at this point in the circuit.
  • a portion of the alternating current across terminals 20 and 22 is rectified by a bridge rectifier 32 and produces across a zener diode 34 a series of flat-topped waves recurring every half cycle of the AC frequency.
  • a bridge rectifier 32 Across the points 36 and 38 is connected the series combination of a ohm resistor 40, SET TEMP. variable resistor 17, and thermistor 16, the latter being embedded in brass probe 10 in the iron sole plate 1.
  • This combination behaves as two arms of a Wheatstone bridge, thepotential at the connecting point of a 1K ohm resistor 42 in series with the base 44b of a 2N 3391 transistor 44 being inversely proportion to the thermistor (and hence the iron sole plate) temperature.
  • transistor 44 The effect of transistor 44 is to quickly charge a 0.47 uF capacitor 46 in the emitter circuit to the potential on the base terminal of transistor 44. During the remainder of the flat-topped wave period, capacitor 46 is further charged from bridge rectifier 32 through a 1M ohm variable resistor 48.
  • the potential at a point 50 during one of the periods is a quick step to a level inversely proportional to iron sole plate temperature followed by a gradual linear rise dependent only upon the setting of the 1M ohm variable resistor48.
  • This potential is applied to the emitter 52e of a 2N 2646 unijunction transistor.
  • the firing potential of transistor 52 is determined purely by the voltage at points 36 and 38 and the ratio of series resistors 54 and 56 in both base leads and is, therefore, constant.
  • These two base resistors comprising 1K ohm 54 from point 36 and the P.T. primary winding 56 from point 38), together with the inherent internal resistance of the base leads, constitute the two other arms of the Wheatstone bridge referred
  • the thermistor l6 resistance will be high and the potential at point 50 will be high at an early point in the half cycle and rises higher thereafter.
  • the initial potential at point 50 will be sufficient to cause unijunction transistor 52 to tire and thus triac 60 will deliver almost a full half cycle pulse to the element of iron 15 during each half cycle.
  • the thermistor 16 resistance will be lower and the initial quick rise of potential at point 50 will be insufficient to fire unijunction transistor 52, this then occurring later in the half cycle during the linear ramp, the amount of delay depending on the precise temperature of the thermistor and the slope setting, determined by l u ohm variable resistor 48.
  • the power pulses to the element of iron are thus shortened and stability is reached when the average power has been reduced until it is just sufiicient to maintain sole plate 1 at the desired temperature.
  • the temperature must drop slightly in order to allow the ramp at point 50 to increase its initial potential and thus fire unijunction transistor 52 earlier in each half cycle.
  • a rise in temperature causes the ramp to start from a lower point and thus fire unijunction transistor 52 later.
  • the limits of operation between full-on and full-off are determined by the slope of the ramp (and hence by the setting of 1M ohm variable resistor 48) and the control for this slope is, therefore, termed the Proportional Band.
  • the triac 60 is further protected from transient voltage surges across terminals and 22 by a diverting network comprising a 1K ohm resistor 62 and a 0.047 uF capacitor 64. Thus, any surges by-pass triac 60 and are dissipated harmlessly in the 64 element of iron 15.
  • an iron having electrical heating means energizable from an electric current source and adapted to heat a sole plate, and a control circuit for said iron comprising,
  • a temperature sensitive element responsive to the temperature of said sole plate to exhibit a change in an electrical value thereof
  • first switching means actuatable in response to discharge of said capacitor
  • a control circuit according to claim 1 including adjustable variable resistance means to regulate the rate of charge of said capacitor.
  • a control circuit according to claim 1 wherein said capacitor is repeatedly charged and discharged in response to a charge in the resistance of said element and wherein said second switching means is actuatable repeatedly in response thereto to provide repeated connection of said heating means to said source whereby power pulses are supplied to said heating means from said source.
  • a control circuit wherein said means responsive to a charge in the resistance of said element to effect charging of said capacitor comprises a transistor; wherein said first switching means comprises a unijunction transistor; and wherein said second switching means comprises a 'triac type solid state device.
  • a control circuit including rectifying means energizable from said electric current source, and wherein said temperature sensitive resistance element, said capacitor, said transistor and said uni unction transistor are in circuit with said rectifying means.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Automation & Control Theory (AREA)
  • Textile Engineering (AREA)
  • Irons (AREA)
  • Thermotherapy And Cooling Therapy Devices (AREA)
US00115979A 1970-02-19 1971-02-17 Iron Expired - Lifetime US3732394A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB790570 1970-02-19

Publications (1)

Publication Number Publication Date
US3732394A true US3732394A (en) 1973-05-08

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Family Applications (1)

Application Number Title Priority Date Filing Date
US00115979A Expired - Lifetime US3732394A (en) 1970-02-19 1971-02-17 Iron

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US (1) US3732394A (de)
DE (1) DE2107924A1 (de)
GB (1) GB1351595A (de)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4347428A (en) * 1979-08-27 1982-08-31 Rowenta-Werke Gmbh Handle and supporting structure for an electric pressing iron having electronic temperature control
US4449035A (en) * 1981-04-07 1984-05-15 Seb S. A. Arrangement for mounting a thermistor-type temperature sensor in a metallic heating device
US4523079A (en) * 1983-09-20 1985-06-11 Black & Decker Inc. Electric iron having electronic control circuit with a power resistor mounted on the soleplate
US4686352A (en) * 1984-04-27 1987-08-11 John Zink Company Electronic pressing iron
USD418649S (en) * 1998-01-31 2000-01-04 Rowenta-Werke Gmbh Steam iron

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE7800655U1 (de) * 1978-01-11 1979-11-15 Dokoupil, Jiri, Dipl.-Ing., 6251 Gueckingen Industriedampfbügeleisen mit elektrisch beheizter und geregelter Sohle
DE2901276A1 (de) * 1979-01-13 1980-07-24 Dokoupil Jiri Buegeleinrichtung fuer industrielle verwendung und zugehoeriges buegeleisen
EP0024613A1 (de) * 1979-08-27 1981-03-11 Rowenta-Werke GmbH Elektrisch beheiztes Bügeleisen
GB2163574A (en) * 1984-08-24 1986-02-26 Thorn Emi Domestic Appliances Domestic electrical appliances

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2694766A (en) * 1950-09-25 1954-11-16 Mcgraw Electric Co Thermostat construction for sadirons
US3286077A (en) * 1964-11-23 1966-11-15 Mc Graw Edison Co Heat-zoned press head

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2694766A (en) * 1950-09-25 1954-11-16 Mcgraw Electric Co Thermostat construction for sadirons
US3286077A (en) * 1964-11-23 1966-11-15 Mc Graw Edison Co Heat-zoned press head

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4347428A (en) * 1979-08-27 1982-08-31 Rowenta-Werke Gmbh Handle and supporting structure for an electric pressing iron having electronic temperature control
US4449035A (en) * 1981-04-07 1984-05-15 Seb S. A. Arrangement for mounting a thermistor-type temperature sensor in a metallic heating device
US4523079A (en) * 1983-09-20 1985-06-11 Black & Decker Inc. Electric iron having electronic control circuit with a power resistor mounted on the soleplate
US4686352A (en) * 1984-04-27 1987-08-11 John Zink Company Electronic pressing iron
USD418649S (en) * 1998-01-31 2000-01-04 Rowenta-Werke Gmbh Steam iron

Also Published As

Publication number Publication date
GB1351595A (en) 1974-05-01
DE2107924A1 (de) 1971-09-16

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