EP1582627A1 - Dispositif de chauffage pour rail - Google Patents

Dispositif de chauffage pour rail Download PDF

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Publication number
EP1582627A1
EP1582627A1 EP04101238A EP04101238A EP1582627A1 EP 1582627 A1 EP1582627 A1 EP 1582627A1 EP 04101238 A EP04101238 A EP 04101238A EP 04101238 A EP04101238 A EP 04101238A EP 1582627 A1 EP1582627 A1 EP 1582627A1
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EP
European Patent Office
Prior art keywords
magnetic
rail
heating device
magnetic field
free ends
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.)
Withdrawn
Application number
EP04101238A
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German (de)
English (en)
Inventor
Lennart Alfredeen
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.)
Mtech Europe AB
Original Assignee
Mtech Europe AB
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Filing date
Publication date
Application filed by Mtech Europe AB filed Critical Mtech Europe AB
Priority to EP04101238A priority Critical patent/EP1582627A1/fr
Publication of EP1582627A1 publication Critical patent/EP1582627A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • E—FIXED CONSTRUCTIONS
    • E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
    • E01B—PERMANENT WAY; PERMANENT-WAY TOOLS; MACHINES FOR MAKING RAILWAYS OF ALL KINDS
    • E01B7/00—Switches; Crossings
    • E01B7/24—Heating of switches

Definitions

  • the present invention relates to a rail heating device according to the preamble of the independent claim.
  • the rail heating device is intended to eliminate a situation where rail points that are covered by ice and/or snow are rendered immovable for switching.
  • a snow-melting apparatus based on another principle i.e., electromagnetic induction, that is, a snow-melting apparatus of the electromagnetic induction heating type
  • a rail snow-melting apparatus by electromagnetic induction heating is disclosed.
  • This known apparatus comprises a high frequency power source, a pair of conductive cables wound in at least one turn around a segment of each rail and through through-holes which are formed through side walls of the rail. Current is supplied from a power source to the conductive cable, thereby heating the rail by the flow of electromagnetically induced current in the rail segment.
  • EP-1,227,186 discloses a line switch part snow melting device for railway track points constituted by connecting a heating coil wound around a floor plate for heating the floor plate by induction to an inverter device for supplying highfrequency current to the heating coil.
  • the object of the present invention is to achieve a device that fulfils all these demands and that may be manufactured to a low cost.
  • the device according to the present invention generally uses a magnetic heating principle that will be discussed in the following.
  • Convection heating can be used which may include direct flame, immersion, radiation, electrical resistance where the heating of the metal is caused by the flow of the electricity and heat may be created by mechanical stresses or friction. Included among these has been induction heating where the heating is caused by use of magnetic fields.
  • induction heating where the heating is caused by use of magnetic fields.
  • a metal workpiece is placed in a coil (or on the surface of the coil supplied with alternating current and the workpiece and the coil are linked by a magnetic field so that an induced current is present in the metal. This induced current heats the metal because of resistive losses similar to any electrical resistance heating.
  • the coil normally becomes heated and must be cooled in order to make the heating of the workpiece as effective as possible.
  • the density of the induced current is greatest at the surface of the workpiece and reduces as the distance from the surface increases. This phenomenon is known as the skin effect and is important because it is only within this depth that the majority of the total energy is induced and is available for heating. Typical maximum skin depths are 40% of one inch (8-10 mm) and three to four inches (8-10 cm) for low frequency applications. In all induction heating applications, the heating begins at the surface due to the eddy currents and conduction carries heat into the body of the workpiece.
  • transfer flux heating Another method of heating metal parts using magnetic fields is called transfer flux heating. This method is commonly used in heating relatively thin strips of metal and transfers flux heat by a rearrangement of the induction coils so that the magnetic flux passes through the workpiece at right angles to the workpiece rather than around the workpiece as in normal induction heating. Magnetic flux passing through the workpiece induces flux lines to circulate in the plane of the strip and this results in the same eddy current loss and heating of the workpiece.
  • US-5,025,124 is disclosed an electromagnetic device for heating metal elements where the heating is accomplished by utilizing a magnetic loop for creating a high density alternating magnetic field in a metal part to be heated.
  • the US-patent is based on the knowledge of replacing, in a magnetic loop, a part of the magnetic core by the metal part to be heated.
  • the metal part is placed between the magnetic poles and may not be used in applications where it is desired to heat the metal parts from one side.
  • an exciter for induction heating apparatus provided with a number of magnetic poles and excitation windings wound on the magnetic poles.
  • the used excitation currents are applied by a phase difference between the current applied to a central magnetic pole and current applied to peripheral magnetic poles.
  • the general objects of the present invention are to achieve a rail heating device that enables a more accurate control of the heating, more even heating and a more power efficient arrangement and that also fulfils the demands discussed above.
  • the present invention is based on a principle where the metal part in form of a rail or a ferromagnetic planar sheet is heated from one side by turning the magnetic field 90 degrees with regard to the magnetic field generated by the magnetic field generator.
  • both paramagnetic and ferromagnetic may be combined in the same heating application.
  • An electrical element according to the present invention has a heating time that is in the order of a couple of minutes compared to tenth of minutes for the electrical elements.
  • Figure 1 is a schematic illustration of a cross-section of a rail 2 provided with a rail heating device 4 according to the present invention.
  • the width of the base of the rail is approximately 13-15 cm and the height is approximately 15-17 cm.
  • the rail heating device has a size, preferably essentially a rectangular or square cross-section with a side length about 2,5-5 cm, preferably 3,5 cm, adapted to easily be positioned as indicated in the figure. Other positions are naturally possible, e.g. further up or further down.
  • the present invention relates to a rail heating device for heating rails 2 of a railroad track, comprising at least two magnetic field generators 6 each having two free ends 8 adapted to be arranged so that they are facing the rail to be heated.
  • the magnetic field generators are controlled by a control means 10 such that they are adapted to generate alternating magnetic fields in said rail, wherein the magnetic fields are converted into heat in the rail.
  • Two magnetic field generators constitute a magnetic module 4.
  • the free ends of the magnetic field generators are arranged in a linear row and the magnetic fields being such that the magnetic field through one of said free ends has an opposite direction as compared to the magnetic fields through the other free ends.
  • Each magnetic field generator comprises a magnetic core 14 having said two free ends and is provided with magnetic coils 16 to which magnetic field generating energy is applied.
  • the magnetic core may consist of laminated silicon sheets, e.g. so called transformer core sheet, or loose powder sintered magnetic material.
  • the magnetic core is preferably U-shaped and has two legs and a joining part, wherein one magnetic coil is arranged on each of the legs. The legs for all magnetic field generators in the magnetic module are parallel.
  • the magnetic core may, alternatively, have any geometrical form provided that the magnetic core has two free ends in the same plane and that the magnetic core together with the ferromagnetic material to be heated forms a closed magnetic loop. Among possible geometrical forms may be mentioned a V-shaped core, an asymmetrical U-shaped core.
  • the magnetic core is divided in two separate rod-shaped legs, wherein at least one magnetic coil is arranged on each of the legs.
  • the magnetic coils are arranged at the magnetic cores.
  • one or many magnetic coils are arranged at the core.
  • Advantageously two coils are used on each core.
  • only one coil may be used on the core arranged e.g. on the lower part of the U-shaped core or on one of the legs, three or more coils may also be arranged at different locations on the core.
  • all different arrangements must be separately tuned, e.g. with regard to fed electrical energy.
  • the magnetic modules are in direct contact to the metal part of ferromagnetic material to be heated.
  • an air-gap or a sheet made of a dielectrical material defining a predetermined distance between the magnetic modules and the metal part to be heated.
  • the thickness of the air-gap (or the dielectrical sheet) is determined in relation to the intended application of the heating device. Generally, the square of the thickness of the air-gap influences the total thickness of the metal part (the thickness of the metal sheets) up to a maximum total thickness (air-gap and metal part) of 90 mm, given an air-gap of 9 mm.
  • an air-gap of 1 or 2 mm was chosen in combination with a ferromagnetic material, e.g. iron, of 4 mm and a paramagnetic material (aluminium) of 2 mm.
  • a ferromagnetic material e.g. iron
  • a paramagnetic material aluminium
  • the metal part to be heated is a ferromagnetic material, e.g. iron, cast iron, magnetic stainless steel and all alloys that include iron.
  • the device further comprises a planar heating means 18 (figure 5) including a ferromagnetic material and constituting a heating surface adapted to face and be in contact with the rail to be heated, wherein said heating means is arranged in or close to a plane defined by said free ends.
  • the heating means comprises two planar sheets, a lower sheet facing the free ends of the magnetic field generators and an upper sheet on the opposite side adapted to face the rail.
  • the upper sheet may be made of a ferromagnetic material , e.g. iron, and the lower sheet may be made from a paramagnetic material, e.g. aluminium.
  • the metal part in the form of a planar sheet may also comprise only a single sheet made from a ferromagnetic material.
  • the combination of ferromagnetic and paramagnetic materials for the sheets constituting the heating means may vary both regarding the choice of material and the thickness of the sheets.
  • a paramagnetic material and a magnetic material the advantage is achieved that the paramagnetic material has a repelling effect, i.e. the H-field is symmetrically spread in the sheets that contribute to the even heating of the heating means.
  • the combination of the paramagnetic and ferromagnetic materials also obtains a shield that prevents the electromagnetic field to be spread.
  • the planar heating means e.g. two metal sheets, are arranged in a plane defined by the free ends of the magnetic cores of the magnetic modules.
  • the lower sheet is a 2 mm sheet of aluminium and the upper sheet is a 4 mm sheet of iron.
  • the two sheets are floating with respect to each other, i.e. they are not fastened (fixed) to each other in order to avoid material stresses related to the different thermal expansions.
  • an air-gap may be provided for between the free ends of the magnetic cores and the planar sheet means.
  • a dielectric sheet e.g. silicone, may be arranged in the air gap with the purpose of obtaining a thermal insulation of the magnetic modules from the heat generated in the metal part.
  • N 1, 2, 3 or 4
  • the number of used modules are dependent of the specific application. Naturally, a much higher number of modules may be used without departing from the present invention which is defined by the appended claims.
  • Another alternative embodiment is to arrange at least two magnetic modules beside each other so that the aligned free ends of the magnetic field generators for each module are parallel. This may be applicable if extra high heating capacity is required.
  • the rail heating device further comprises a rigid outer enclosure 12 adapted to protect the device from mechanical damages and environmental influences, e.g. snow or ice.
  • the enclosure has preferably the shape of a U-shaped beam.
  • the outer enclosure is also provided with a fastening means (not shown) for attaching the device to the rail.
  • FIG 2 is also illustrated an energy feeding means 20 adapted to feed electrical energy to the coils of the module, control means 10 that controls the feeding means in accordance to input signals received from a control panel 22 where an operator may input various parameters related to the heating, e.g. desired target temperature, heating rate etc.
  • the device preferably comprises at least one temperature sensor arranged close to the plane of the free ends, wherein said sensor generates temperature signals that are applied to the control means and used to control the heating of the device.
  • a temperature sensor (not shown) is arranged beneath the ferromagnetic sheet.
  • the temperature sensor generates a temperature signal to the control means in order to increase the accuracy in the control of the heating device.
  • the temperature sensor is further discussed below.
  • Temperature sensors may alternatively be arranged between the ferromagnetic sheet and the paramagnetic sheet. Experiments performed by the inventor show that one sensor per magnetic module give an accurate temperature control.
  • the sensor is preferably arranged in a central location of the magnetic module. It would also be possible to use more sensors if the application requires an even more accurate temperature control.
  • the temperature sensor used in the present invention is preferably a thermo couple element sensor (e.g. type K), which is a passive sensor provided with two thin wires of different materials that generates a direct current in dependence of the temperature.
  • This type of sensors have a fast response time, e.g. in the order of 50 ms and are also be heat resistant up to at least 1000 degrees.
  • Figure 6 is an illustration of the electrical energy feeding of one magnetic module that is schematically shown from above to the right in the figure where the numbers 1-4 designate the four magnetic coils.
  • coil number 2 is connected to the reversed polarity compared to the three other.
  • Each magnetic module is provided with two connections f1 and f2, where f1 is connected to the input of three of the coils and f2 is connected to the output of these three coils.
  • connection f2 is connected to the input and f1 to the output.
  • f1 and f2 are preferably connected to two phases in a three-phase system.
  • magnetic modules are connected to the power source so that no phase shifting is induced resulting in the generation of reactive power.
  • each coil could be separately fed instead and in that case the correct polarity for each coil should be controlled by the control means.
  • the frequency of the electrical power generated by the power source and applied to the magnetic modules is preferably in the range of 50-60 Hz. However, a much wider frequency range, e.g. 10-500 Hz, is naturally possible to use including the frequencies 16 2/3 Hz and 400 Hz.
  • Still another possibility is to use an even higher frequency, in the order of some kHz.
  • One problem when using a higher frequency is the heat generated by the coils. By applying the magnetic field generating energy by using pulses of high frequency power the heating of the coils is easily reduced.
  • a so-called controlled disconnection of the magnetic modules is applied.
  • This controlled disconnection is controlled by the control means and provides that the disconnection is made exactly at or close to a zero crossing of the magnetic field generating energy which results in that no magnetic reminiscence remains.
  • Figures 7-10 schematically illustrate by arrows the magnetic field deflections in a magnetic module that is fed with energy by using the circuitry illustrated in figure 6.
  • Figures 7 and 9 show a magnetic module from below and illustrate the magnetic fields in the plane of the free ends of the magnetic field generators.
  • coil number two from above is fed with reversed polarity compared to the other coils, i.e. the free end that has an opposite directed magnetic field is one of the two inner free ends of a magnetic module. It is naturally also possible that the free end that has an opposite directed magnetic field is one of the two outer free ends of a magnetic module.
  • the situation at the phase position 90 degrees is illustrated showing the magnetic field core is directed inwards and downwards (see figure 8).
  • the magnetic fields for the other cores are directed outwards and upwards (see figure 8).
  • figures 9 and 10 the situation at the phase position 270 degrees is illustrated where the directions of all magnetic fields are reversed as compared to figures 7 and 8.
  • the rail heating device according to the present invention is primarily intended for use in a railroad switcher where high capacity is of greatest importance.
  • the energy is put directly on the surface and the surface is then heated to an appropriate temperature for melting snow/ice, e.g. in the range 5-50 °C.
  • the ferromagnetic sheet constituting surface facing that rail may advantageously be coated by some suitable coating material especially adapted for the special requirements in this application.
  • a control panel including an information display showing the temperature etc., input means, e.g. knobs, for setting various parameters related to the heating, e.g. the heating rate and the target temperature.
  • each magnetic module comprises two magnetic field generators and each magnetic field generator has two free ends (or poles), i.e. each magnetic module has four poles.
  • the coil of one leg of a magnetic field generator is fed by a reversed polarity as compared to the feeding of the other three coils of the magnetic module.
  • the magnetic field of the single pole attracts one of the magnetic fields from one of the other three poles and as a result two remaining (left-over) magnetic fields having the same polarity are obtained.
  • the rail heating device according to the present invention is a number of close-related variants are possible. Among those may be mentioned heating of arrangements intended to work in tough weather conditions.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Architecture (AREA)
  • Civil Engineering (AREA)
  • Structural Engineering (AREA)
  • General Induction Heating (AREA)
EP04101238A 2004-03-25 2004-03-25 Dispositif de chauffage pour rail Withdrawn EP1582627A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP04101238A EP1582627A1 (fr) 2004-03-25 2004-03-25 Dispositif de chauffage pour rail

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP04101238A EP1582627A1 (fr) 2004-03-25 2004-03-25 Dispositif de chauffage pour rail

Publications (1)

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EP1582627A1 true EP1582627A1 (fr) 2005-10-05

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EP04101238A Withdrawn EP1582627A1 (fr) 2004-03-25 2004-03-25 Dispositif de chauffage pour rail

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2012050502A1 (fr) 2010-10-15 2012-04-19 Kkm Ab Dispositif de chauffage de voies de chemin de fer
EP2720513A1 (fr) * 2012-10-15 2014-04-16 IFF GmbH Dispositif inductif de chauffage d'aiguille et/ou de rail
WO2017142473A1 (fr) * 2016-02-18 2017-08-24 Indheater Ab Dispositif et procédé pour faire fondre la neige et la glace d'une voie ferrée

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5389766A (en) * 1992-11-27 1995-02-14 Fuji Electric Co., Ltd. Rail snow-melting by electromagnetic induction heating
JPH07288177A (ja) * 1994-04-18 1995-10-31 Nippon Koei Co Ltd レールポイント凍結防止電熱装置

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5389766A (en) * 1992-11-27 1995-02-14 Fuji Electric Co., Ltd. Rail snow-melting by electromagnetic induction heating
JPH07288177A (ja) * 1994-04-18 1995-10-31 Nippon Koei Co Ltd レールポイント凍結防止電熱装置

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 1996, no. 02 29 February 1996 (1996-02-29) *

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2012050502A1 (fr) 2010-10-15 2012-04-19 Kkm Ab Dispositif de chauffage de voies de chemin de fer
US20140151366A1 (en) * 2010-10-15 2014-06-05 Kkm Ab Railway Track Heating Device
EP2627823A4 (fr) * 2010-10-15 2015-05-13 Kkm Ab Dispositif de chauffage de voies de chemin de fer
RU2595997C2 (ru) * 2010-10-15 2016-08-27 Ккм Аб Устройство для нагрева железнодорожных путей
US10619310B2 (en) 2010-10-15 2020-04-14 Stegia Ab Railway track heating device
EP2720513A1 (fr) * 2012-10-15 2014-04-16 IFF GmbH Dispositif inductif de chauffage d'aiguille et/ou de rail
WO2017142473A1 (fr) * 2016-02-18 2017-08-24 Indheater Ab Dispositif et procédé pour faire fondre la neige et la glace d'une voie ferrée

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