US2751502A - High-frequency heating generator - Google Patents

High-frequency heating generator Download PDF

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Publication number
US2751502A
US2751502A US303195A US30319552A US2751502A US 2751502 A US2751502 A US 2751502A US 303195 A US303195 A US 303195A US 30319552 A US30319552 A US 30319552A US 2751502 A US2751502 A US 2751502A
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US
United States
Prior art keywords
coil
generator
water
anode
cooling water
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
US303195A
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English (en)
Inventor
Blok Lourens
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.)
Hartford National Bank and Trust Co
Original Assignee
Hartford National Bank and Trust Co
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 Hartford National Bank and Trust Co filed Critical Hartford National Bank and Trust Co
Application granted granted Critical
Publication of US2751502A publication Critical patent/US2751502A/en
Anticipated expiration legal-status Critical
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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
    • H05B6/00—Heating by electric, magnetic or electromagnetic fields
    • H05B6/02—Induction heating
    • H05B6/04—Sources of current

Definitions

  • This invention relates to high-frequency heating generators comprising an electronic tube oscillator having a water-cooled primary or tank coil which is closely surrounded by a secondary or coupling coil in the form of a circularly bent metal. strip.
  • the water cooling of the tank coil is required to enable the heat produced by the high-frequency losses in the coil to be conducted away.
  • the secondary coil has only one turn and is connected to the (external) heating coil, in the field of which the material to be heated is arranged.
  • the coupling between the primary and secondary coils should be comparatively tight and hence the secondary is required to surround the tank coil, for example, with a 10 w. generator the intermediate spacing is about 7 mm.
  • a high-frequency heating generator comprising a discharge tube oscillator having a water-cooled tank coil which is closely surrounded by a secondary coil in the form of a circularly bent metal strip, is characterized in that the supply pipe for cooling water for cooling the coil contains an electrically controllable valve and control means are provided to permit flow of cooling water only when the generator is in use, but does not act to any appreciable extent on the supply of the cooling water to the anode of the oscillating tube.
  • valvecontrol electro-magnet in a circuit in which the magnet winding is connected into circuit simultaneously with the anode supply transformer of the generator.
  • cooling water flows only when the anode supply voltage of the oscillating tube is connected into circuit and does not flow when this voltage is cut oil, the coil being thus prevented from becoming cooled to a temperature lower than the temperature of the atmosphere.
  • Fig. l is a perspective view of the essential parts of an embodiment of the invention.
  • Fig. 2 is a sectional detail view thereof.
  • Fig. 1 shows a water-cooled coil system of a highfrequency heating generator comprising a primary coil 1 Wound from copper tubing and a copper strip 3 which, bent to form a cylindrical shell closed but for a small slit, is arranged to surround the coil co-axially and constitutes a secondary coil.
  • the copper strip is bent outwardly at right angles thereto and the two ends 3 and 3" of the strip are arranged spatially parallel to one another with a very small intermediate space of, say, one millimeter, are substan tially radial to the circularly bent part and constitute connections to a heating coil (not shown) which may be screwed to two copper connecting blocks 5 and 7 secured to the ends 3 and 3", respectively.
  • the coil 1 is wound on a support comprising three radially arranged strips 9 of low-loss insulating material which each has one end secured to a vertical metal wall which forms part of a transportable frame 11.
  • the coil 1 can be moved into and out of the secondary coil 3 to vary the coupling and thus control the output energy.
  • T he coil 1 has cooling water fed to it through a flexible tube 13.
  • the cooling water passes through the coil 1, a second rubber tube 15, a connecting pipe 17, flexible tubes 19, 21 and 23, and hence flows through the con necting blocks 5 and 7, and passes finally through a discharge pipe 25.
  • the maximum coupling between the coils 1 and 3 is required to be very tight in order that in practice it may be possible at any load to feed the maximum energy to the heating coil.
  • the diiierence in spacing between the primary and secondary coils is therefore small. With a 10 kw. generator, the spacing is about 1 cm., the primary coil having a diameter of about 30 cm. Due to divergence from exact co-axial arrangement of the coils 1 and 3 which can only with difiiculty be avoided, a minimum spacing of about 7 mm. may be assumed. This is sufficient to avoid arcing between the coils under normal conditions.
  • the operation of the generator is continuously interrupted temporarily by switching off the anode supply voltage of the thermionic tube, the other supply potentials and auxiliary potentials remaining connected. If cooling water were permitted to continue to flow when no heating of the core 1 by high-frequency losses in the coil 1 was taking place, the coil might be cooled by the cooling waterthe temperature of which may be 12 C.-to below the dew point of the surrounding atmosphere with the result that vapour would condense on the coil and drops suspended from the coil 1 would be liable to bring about arcing between the coils l and 3 on the anode voltage again being supplied to the discharge tube.
  • the water supply pipe contains an electrically controllable valve 29 which permits flow of cooling water only when the generator is in use but does not act to any appreciable extent on the cooling circuit for the anodes of the oscillating tubes.
  • the valve shown in Fig. 2 is of known construction and comprises a stud 31 having a conical end which in its normal position closes an entry-port 33, thus shutting oil? the flow of cooling water.
  • the valve control device comprises an electro-magnet 35 the armature 37 of which, on energization of the magnet, raises the stud 31 against the pressure of a spring 39.
  • the magnet 35 may be included in an auxiliary circuit which is established and broken by a contact of a relay 43 by which anode-voltage supply transformer 41 is controlled.
  • the flow of cooling water through the coil 1 is consequently interrupted when the generator is not in use; the water that may be available within the coil is always warm enough to avoid condensation.
  • the device described above is not efiective if the oscillator stops oscillating for a short period due to a fault or to excessive load and thereafter again starts to oscillate, in which case condensation of vapour on the coil and arcing are therefore liable to occur. If desired, this may also be taken into account, for example, by energizing the magnet 35 with the use of a direct current obtained by rectification of a small part of the high-frequency output current of the tube or with the use of a current controlled by such rectified current With the aid of a relay or relays.
  • a high-frequency generator comprising; a discharge tube oscillator provided with a water-cooled anode, a water-cooled primary coil operatively connected to said oscillatory, a secondary coil in the form of a circularly bent metal strip surrounding said primary coil with relatively small spacing therebetween, a water supply pipe for cooling the primary coil, and an electrically controllable valve in said water supply pipe including an armature, a source of electrical current, an electromagnet which upon magnetization operates said valve to permit the flow of cooling water only when said generator and said electromagnet have said current applied thereto but does not interrupt the continual supply of water to the anode of said oscillator.
  • a high-frequency generator comprising; a discharge tube oscillator provided with a Water-cooled anode, a water-cooled primary coil operatively connected to said oscillator, a secondary coil in the form of a circularly bent metal strip surrounding said primary coil with relatively small spacing therebetween, said circularly bent metal strip having two elongated ends extending radially from said metal strip and transverse to the axis thereof, said two ends being parallel-spaced and each having a connecting block secured thereto, a water supply pipe for cooling the primary coil, and an electrically controllable valve in said water supply pipe including an armature, a source of electrical current, and electromagnet which upon magnetization operates said valve to permit the flow of cooling water only when said generator and said electromagnet have said current applied thereto but does not interrupt the continual supply of water to the anode of said oscillator.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • General Induction Heating (AREA)
  • Water Treatment By Electricity Or Magnetism (AREA)
US303195A 1951-09-26 1952-08-07 High-frequency heating generator Expired - Lifetime US2751502A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL305864X 1951-09-26

Publications (1)

Publication Number Publication Date
US2751502A true US2751502A (en) 1956-06-19

Family

ID=19783485

Family Applications (1)

Application Number Title Priority Date Filing Date
US303195A Expired - Lifetime US2751502A (en) 1951-09-26 1952-08-07 High-frequency heating generator

Country Status (6)

Country Link
US (1) US2751502A (pt)
BE (1) BE514401A (pt)
CH (1) CH305864A (pt)
DE (1) DE922007C (pt)
FR (1) FR1063611A (pt)
GB (1) GB708796A (pt)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3535809A (en) * 1967-11-03 1970-10-27 Hoffmann Werke Oswald Firing equipment for simulating gunfire

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1987458A (en) * 1928-11-16 1935-01-08 Youngstown Sheet And Tube Co Induction heater
US2138181A (en) * 1933-01-14 1938-11-29 Rca Corp Short wave signaling
US2403969A (en) * 1943-03-10 1946-07-16 Jacob H Fledel-Beck Split induction coil furnace
US2404404A (en) * 1943-05-15 1946-07-23 Rca Corp High-frequency apparatus
US2455822A (en) * 1944-06-07 1948-12-07 Sunbeam Corp Apparatus for heat-treating metal parts
US2672544A (en) * 1948-11-30 1954-03-16 Marocaine Tech Et Commerciale Apparatus for welding by means of electromagnetic induction heating

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1987458A (en) * 1928-11-16 1935-01-08 Youngstown Sheet And Tube Co Induction heater
US2138181A (en) * 1933-01-14 1938-11-29 Rca Corp Short wave signaling
US2403969A (en) * 1943-03-10 1946-07-16 Jacob H Fledel-Beck Split induction coil furnace
US2404404A (en) * 1943-05-15 1946-07-23 Rca Corp High-frequency apparatus
US2455822A (en) * 1944-06-07 1948-12-07 Sunbeam Corp Apparatus for heat-treating metal parts
US2672544A (en) * 1948-11-30 1954-03-16 Marocaine Tech Et Commerciale Apparatus for welding by means of electromagnetic induction heating

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3535809A (en) * 1967-11-03 1970-10-27 Hoffmann Werke Oswald Firing equipment for simulating gunfire

Also Published As

Publication number Publication date
DE922007C (de) 1955-01-07
CH305864A (de) 1955-03-15
GB708796A (en) 1954-05-12
BE514401A (pt)
FR1063611A (fr) 1954-05-05

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