EP0573430B1 - Electric tubular heating element comprising a temperature controller therefor - Google Patents

Electric tubular heating element comprising a temperature controller therefor Download PDF

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Publication number
EP0573430B1
EP0573430B1 EP91918628A EP91918628A EP0573430B1 EP 0573430 B1 EP0573430 B1 EP 0573430B1 EP 91918628 A EP91918628 A EP 91918628A EP 91918628 A EP91918628 A EP 91918628A EP 0573430 B1 EP0573430 B1 EP 0573430B1
Authority
EP
European Patent Office
Prior art keywords
heating element
tubular heating
terminal
temperature controller
bimetal switch
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
EP91918628A
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0573430A1 (en
Inventor
Kjell-Ake Elofsson
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.)
Backer Elektro-Varme AB
Original Assignee
Backer Elektro-Varme AB
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 Backer Elektro-Varme AB filed Critical Backer Elektro-Varme AB
Publication of EP0573430A1 publication Critical patent/EP0573430A1/en
Application granted granted Critical
Publication of EP0573430B1 publication Critical patent/EP0573430B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B1/00—Details of electric heating devices
    • H05B1/02—Automatic switching arrangements specially adapted to apparatus ; Control of heating devices
    • H05B1/0202—Switches
    • H05B1/0213—Switches using bimetallic elements
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B3/00—Ohmic-resistance heating
    • H05B3/40—Heating elements having the shape of rods or tubes
    • H05B3/42—Heating elements having the shape of rods or tubes non-flexible
    • H05B3/48—Heating elements having the shape of rods or tubes non-flexible heating conductor embedded in insulating material

Definitions

  • the present invention relates to an electric tubular heating element comprising a tubular metal casing which contains a coil of resistance wire surrounded by an insulating material, and a temperature controller connected in series with a resistance-wire coil and arranged at one end of the metal casing and comprising an insulating sleeve which contains a bimetal switch and has an outer terminal forming a terminal of the tubular heating element, and an inner terminal which later, when the temperature controller is mounted in the tubular heating element, contacts a terminal connected to the resistance-wire coil.
  • the prior art encompasses electric tubular heating elements of this type.
  • the temperature controller used in the prior-art tubular heating elements is of single-use type, such as a fuse, or of reclosing type, such as a bimetal switch.
  • the object of the present invention is, therefore, to provide at tubular heating element with a temperature controller not impaired by the drawbacks of the prior art.
  • Such a temperature controller must meet the following requirements.
  • EP-A-0 204 850 discloses an electric tubular heating element having a temperature controller consisting of a bimetal switch which always returns automatically when the temperature falls to the normal value.
  • This electric tubular heating element does meet only a few of the above requirements. It could be made recloseable manually by the introduction of a manually recloseable bimetal switch, such as described in e.g. DE-A-3 644 514 and DE-A-3 320 730.
  • DE-B-1 125 567 discloses an electrical tubular heating element having a reclosable bimetal switch and a parallel-connected resistor element.
  • an electric tubular heating element which is of the type stated in the introduction to this specification and which has the characterising features stated in claim 1.
  • Preferred embodiments of the electric tubular heating element according to the invention have the features stated in claims 2-7.
  • the inner and outer terminals have tongues facing one another, the bimetal switch and the resistor element being fixed one on each side of said tongues.
  • rivets may be used, one of which may also constitute the fixed contact of the bimetal switch.
  • the resistor element advantageously is a PTC-resistor, i.e. a resistor element whose resistance has a positive temperature coefficient.
  • the temperature controller according to the invention meets the above requirements a) - f) in that
  • the inventive electric tubular heating element shown in Fig. 1 consists of a tubular metal casing 1 which has a resistance-wire coil 2 extended between two terminals in the form of pins 3 and 4.
  • the resistance-wire coil is surrounded by, and insulated from the casing 1 by means of, a pulverulent insulating material 5, such as magnesia powder.
  • the two ends of the wire coil are in conventional manner fixed to the inner ends of the pins 3, 4, e.g. by welding.
  • a temperature controller 6 is according to the invention mounted in the left end of the tubular heating element, as seen in Fig. 1.
  • the temperature controller 6 has an inner terminal in the form of a contact socket 7 (Fig. 3) which encloses and electrically contacts the terminal pin 3 of the resistance-wire coil 2.
  • the oppositely directed terminal 8 of the temperature controller 6 projects from the end of the tubular heating element in the form of a pin and forms the second electric terminal thereof.
  • the metal casing 1 extends a certain distance along the terminal 8, i.e. it contains substantially the entire temperature controller 6, and an end bushing 9 of steatite or polymers forms a seal between the metal casing 1 and the terminal 8 and also serves to maintain the latter in place.
  • the terminal 4 may be either directly connected to the resistance-wire coil 2 or connected thereto via a temperature controller corresponding to the controller 6.
  • Fig. 2 illustrates an alternative tubular heating element, in which the terminals 3', 4' of the resistance-wire coil 2' are provided at the same end of the metal casing 1'. The other end of the metal casing 1' is closed, and the resistance-wire coil 2' extends from one end of the casing 1' to the other and back embedded in an insulating material 5'.
  • two temperature controllers 6', 6" according to the invention are each connected to a terminal 3', 4'.
  • the temperature controllers 6' and 6" in the embodiment of Fig. 2 unlike that of Fig. 1, are not substantially contained in the metal casing 1' but in an extension piece thereof which consists of a bushing 10 and a tubular member 11.
  • the tubular member 11 is mounted in the bushing 10 which in turn is fixedly mounted on the metal casing 1'. Further, the bushing 10 has a threaded portion for fixing the tubular heating element.
  • the outer terminals 8', 8" of the temperature controllers 6', 6" are electrically connected to two conductors in an electric cable 12 through which current is supplied to the resistance-wire coil 2'.
  • the preferred embodiment of an inventive temperature controller shown in Fig. 3 comprises a sleeve 13 of an insulating material, such as plastic, preferably of a circular cross-section corresponding to e.g. the cross-section of the metal casing 1 in Fig. 1.
  • the terminals 7 and 8 are mounted each in one end of the sleeve 13, the terminal 7 consisting of a cylinder 14 which is made in one piece with a contact socket 15 slotted in the longitudinal direction, and a tongue 16 facing away from the socket and disposed in a plane through a diameter of the cylinder 14.
  • the terminal 8 consists of a pin which is fixedly mounted in an end wall of the sleeve 13 and has a tongue 17 extending into the free space inside the sleeve 13. The tongue 17 is located in the same plane as the tongue 16.
  • a resistor element 19 is fixed to the tongue 17 by a rivet 18.
  • the other end of the resistor element 19 is fixed to the tongue 16 by a rivet 20.
  • One end of a bimetal spring 21 is fixed to the tongue 16 by the rivet 20 on that side of the tongue 16 which is opposite to the resistor element 19.
  • the bimetal spring 21 extends in over the tongue 17 and, when in closed position, contacts the rivet 18 which thus forms the fixed contact of the bimetal switch formed by the rivet and the bimetal spring 21.
  • the bimetal spring 21 is located substantially at the centre of the casing 13 and has the shape illustrated in Fig. 4.
  • the resistor element 19 has the shape shown in Fig. 5.
  • holes have been formed in the tongues 16 and 17 and in the resistor element 19 and one end of the bimetal spring 21, as shown in Figs 4 and 5.
  • the contact socket 15 When mounting the temperature controller of Fig. 3 in e.g. the tubular heating element of Fig. 1, the contact socket 15 will contact the pin 3, and the terminal 8 will form one terminal of the tubular heating element. It should here be observed that the sleeve 13, after the details housed therein have been mounted, has been given a decreasing diameter at its free end, just beyond the contact socket 15, thereby ensuring the electric strength between the contact socket 15 and the metal casing 1.
  • the resistor element 19 can be made of any suitable material of sufficiently high resistivity, but a material whose resistance has a positive temperature coefficient is preferred, since it ensures the desired limitation of the current through the tubular heating element after the bimetal switch has been tripped.
  • the bimetal spring 21 will, at a given temperature, rise from the fixed contact 18, thereby breaking the normal path of the current through the resistance-wire coil 2. A slight current, depending on the resistance of the resistor element 19, will continue to flow through the resistance-wire coil 2 via the resistor element 19. Thus, this element is heated and the generation of heat is so dimensioned that the bimetal spring 21 cannot bend back and contact the fixed contact 18. To reconnect the tubular heating element, thus also the slight current through the resistor element 19 must be interrupeted.

Landscapes

  • Thermally Actuated Switches (AREA)
  • Measurement And Recording Of Electrical Phenomena And Electrical Characteristics Of The Living Body (AREA)
  • Electromechanical Clocks (AREA)
  • Measurement Of The Respiration, Hearing Ability, Form, And Blood Characteristics Of Living Organisms (AREA)
  • Cooling Or The Like Of Electrical Apparatus (AREA)
  • Control Of Resistance Heating (AREA)
  • Resistance Heating (AREA)
EP91918628A 1990-10-25 1991-10-23 Electric tubular heating element comprising a temperature controller therefor Expired - Lifetime EP0573430B1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
SE9003405 1990-10-25
SE9003405A SE9003405D0 (sv) 1990-10-25 1990-10-25 Elektriskt roervaermeelement och temperatursaekring
PCT/SE1991/000710 WO1992008331A1 (en) 1990-10-25 1991-10-23 Electric tubular heating element and temperature controller therefor

Publications (2)

Publication Number Publication Date
EP0573430A1 EP0573430A1 (en) 1993-12-15
EP0573430B1 true EP0573430B1 (en) 1998-05-20

Family

ID=20380736

Family Applications (1)

Application Number Title Priority Date Filing Date
EP91918628A Expired - Lifetime EP0573430B1 (en) 1990-10-25 1991-10-23 Electric tubular heating element comprising a temperature controller therefor

Country Status (6)

Country Link
EP (1) EP0573430B1 (fi)
AT (1) ATE166519T1 (fi)
DE (1) DE69129468T2 (fi)
FI (1) FI931851A (fi)
SE (1) SE9003405D0 (fi)
WO (1) WO1992008331A1 (fi)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB9124965D0 (en) * 1991-11-25 1992-01-22 Sheathed Heating Elements Ltd Thermostatic control device
CN116130122B (zh) * 2023-01-18 2023-08-11 哈尔滨工程大学 一种用于热管冷却反应堆的功率自动控制系统

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1014676B (de) * 1955-07-11 1957-08-29 Arthur Liebrecht Heizelement fuer elektrisch beheizte Geraete, insbesondere Waschmaschinen
DE1125567B (de) * 1956-06-22 1962-03-15 Walter Hering Dipl Ing Heizelement fuer elektrisch beheizte Geraete, insbesondere Waschmaschinen
DE2513494C2 (de) * 1975-03-26 1984-07-19 Peter 7530 Pforzheim Hofsäss Temperaturschutzschalter für Rohrheizkörper
GB1568991A (en) * 1976-03-26 1980-06-11 Ellson & Co Ltd C Submersible thermostatically controlled heaters
DE3320730A1 (de) * 1983-01-15 1984-07-19 Fritz Eichenauer GmbH & Co KG, 6744 Kandel Temperaturwaechter
EP0204850A1 (de) * 1985-06-05 1986-12-17 Elpag Ag Chur Rohrheizkörper
DE3644514A1 (de) * 1986-12-24 1988-07-07 Inter Control Koehler Hermann Bimetallschalter

Also Published As

Publication number Publication date
ATE166519T1 (de) 1998-06-15
SE9003405D0 (sv) 1990-10-25
DE69129468D1 (de) 1998-06-25
EP0573430A1 (en) 1993-12-15
WO1992008331A1 (en) 1992-05-14
FI931851A0 (fi) 1993-04-23
DE69129468T2 (de) 1998-11-26
FI931851A (fi) 1993-06-17

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