US2181274A - Induction heater construction - Google Patents

Induction heater construction Download PDF

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Publication number
US2181274A
US2181274A US207342A US20734238A US2181274A US 2181274 A US2181274 A US 2181274A US 207342 A US207342 A US 207342A US 20734238 A US20734238 A US 20734238A US 2181274 A US2181274 A US 2181274A
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secondary
resistance
magnetic
sheath
induction heater
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Expired - Lifetime
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US207342A
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Lloyd R Jackson
Howard W Russell
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Utilities Coordinated Res Inc
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    • HELECTRICITY
    • H05ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05BELECTRIC HEATING; ELECTRIC LIGHTING NOT OTHERWISE PROVIDED FOR
    • H05B6/00Heating by electric, magnetic, or electromagnetic fields
    • H05B6/02Induction heating
    • H05B6/10Induction heating apparatus, other than furnaces, for specific applications
    • H05B6/105Induction heating apparatus, other than furnaces, for specific applications using a susceptor
    • H05B6/108Induction heating apparatus, other than furnaces, for specific applications using a susceptor for heating a fluid

Description

Nov. 28, 1939. 1.. R. JACKSON ET AL INDUCTION HEATER CONSTRUCTION Filed May 11, 1958 ATTORNEY.

} Patented Nov. 28, 1939 UNITED STATES PATENT OFFICE INDUCTION HEATER CONSTRUCTION Lloyd IL Jackson and Howard W. Russell, Columbus, Ohio, assignors to Utilities Coordinated Research, Inc., New York, N. Y., a corporation of New York This invention relates to induction heaters and has for its object to provide aheater of this type having a predetermined power factor and eiilciency.

It has long been known and use has been made of the fact that where alternating current is applied to a coil wound around a cylindrical metallic container that eddy currents will be induced in the walls of the container, the heating eiiect of which can be employed for useful purposes. It has further been known that when the container is made out of a magnetic material such as iron, the size of induced currents and thereby the heating effect are much improved so long as opcrating temperatures are such that the container remains magnetic.

Devices of the type described have, in general, a low power factor and other undesirable operating characteristics. that an improvement in power factor can be secured by surrounding the magnetic core of the device with a single turn secondary winding in the form of a non-magnetic but electrically conducting sheath.

While it has been known that a non-magnetic low resistance sheath such as described above will improve the power factor of an induction heater, we have discovered that this improvement in power factor may be accompanied by certain undesirable features. The principal object of this invention is to teach the method of choosing the sheath resistance according to principles which we have discovered so that the undesirable features may be avoided.

More specifically the objects of this invention are to teach the choice of sheath resistance either for maximum electrical efficiency, or for maximum secondary power or for the best possible combination of efliciency and power factor.

Other objects and advantages will become more fully apparent as reference is had to the accompanying drawing wherein my invention is illustrated, and in which:

Fig. l is a diametric longitudinal section through an induction heater, shown for demonstrative purposes, and

Fig. 2 is an end view of the heater of Fig. 1'.

More particularly, I indicates a metallic core through which, or in which, a fluid, viscuous or solid material, to be heated may fiow or be contained. The core may vary in thickness of sidewalls to the point of being solid and may have any desired or given exterior shape, but is here illustrated as being round.

The core I may be of iron, steel or the like It has been known, however,

and is covered by a thin sheet of non-magnetic but electrically conducting material, which acts as a single turn secondary winding. It has been previously practiced to apply a coating of copper to the core I, however, as will be demonstrated, 5 this coating should have a greater electrical resistance than is offered by copper and is preferably made of a material such as brass. This sheath may be made of a thin sheet such as foil and may be wrapped and soldered or coated by electrolysis or installed by any other suitable method.

Enveloping the sheath 2 is an electrically insulating material 3 and wrapped therearound is a multiplicity of turns of wire 4 constituting the primary winding, one end of which is connected to a source of current supply 5, grounded at 6 and the other end of which is grounded at 1.

An induction heater of this type was constructed in which the primary consisted of 400 20 turns of #14 wire, the construction being such that the sheath 2 thereof could be removed and replaced by others. Thus it was possible to vary the secondary sheath resistance without changing any of the other heater constants.

Three types of experiments were conducted with this heater. In the first experiment no sheath was used and secondary heating currents were induced in the magnetic portion of the secondary. This arrangement attached to 100 volts produced a secondary heating power of only 600 watts at a power factor of .695 and an efiiciency of 95%.

In the next experiment the old practice of making the secondary resistance as low as possible was followed. A low resistance secondary sheath made from copper was used for this experiment and the arrangement produced 3220 watts of heating power at a power factor of 0.895 and an efficiency of 71%. Thus, as older practice predicted, the heating power was increased and the power factor much improved by the use of the sheath, however, the efliciency is low.

In the third experiment a brass sheath was used having its resistance chosenaccording to our principle of combining high efficiency and high power factor. This sheath had a resistance about 10 times as great as that used in the second experiment. This arrangement produced a 50 secondary heating power of 1900 Watts with an efliciency of 89.5% and a power factor of 0.97. These results indicate a substantial improvement in power factor and efiiciency by the use of a relatively high resistance sheath-a result contrary to that which would be predicted by the teachings of previous investigators.

As a result of numerous experiments and calculations the following conclusions were established.

To obtain maximum electrical efiiciency from an induction heater we have discovered that the secondary resistance should be chosen according to the equation where T2 is the resistance of the sheath and wL: is the secondary inductive reactance.

To obtain maximum secondary power from a heater regardless of the efliciency and power factor the sheath resistance should be chosen according to the equation is the ratio of primary inductive reactance to primary resistance and the coupling factor=1.

To construct a heater which will exhibit the best possible combination of efliciency and power factor-that is, high efliciency and high power factor the sheath resistance should be chosen according to the equation WLg (EL To construct a heater which will provide the highest secondary heating power at the best efficiency possible the secondary resistance should be chosen according to the equation where as the arrangement fulfills the condition that current flowing in the part designated as the primary will induce heating currents in the part designated as the secondary and the secondary is composed of a magnetic and a non-magnetic portion.

What is claimed is:

1. In an induction heater, a primary portion and a secondary portion, said secondary portion comprising a magnetic portion and a non-magnetic portion, the resistance of said non-magnetic portion being substantially equal to the inductive reactance of said secondary portion.

2. In an induction heater, 2, primary portion and a secondary portion, said secondary portion comprising a magnetic portion and a non-magnetic portion, said non-magnetic portion being composed of brass and having an electrical resistance substantially equal to the inductive reactance of said secondary portion.

3. An induction heater composed of a core of magnetic material, a primary winding around said core, and connected to a source of electric current'supply, and a single turn secondary winding between said core and said primary winding, said secondary winding being in the form of a non-magnetic electrically conductive sheath and having a resistance substantiallyequal to the secondary inductive reactance divided by the square root of the ratio of the primary inductive reactance and the primary resistance squared plus 1.

4. An induction heater comprising a primarywinding and a secondary winding, said secondary winding being composed of non-magnetic, electrically conductive material and having a resistance substantially equal to the secondary inductive reactance divided by the cube root of the ratio of primary inductive reactance to primary resistance.

5. An induction heater composed of a comet magnetic material, a primary winding around said core, and connected to a source of electric current supply, and a single turn secondary winding between said core and said primary winding, said secondary winding being in the form of a non-magnetic electrically conductive sheath and having a resistance substantially equal to the secondary inductive reactance divided by the cube root of the ratio of Primary inductive reactance to primary resistance.

6. The method of designing the secondary of an induction heater for maximum electrical efllciency comprising a magnetic and a nommagnetic portion which consists in selecting the resistance of said non-magnetic portion such that it is substantially equal to the reactance of said secondary.

7. The method of designing for maximum secondary power an induction heater having a secondary composed of a magnetic and non-magnetic portion which consists in selecting the resistance of said non-magnetic portion according to the formula where m is the resistance of said non-magnetic portion, 1.0L: is the secondary inductive reactance,

where r: is the resistance of said non-magnetic portion, wLz is the secondary inductive reactance and is the ratio of the primary inductive reactance to primary resistance.

LLOYD R. JACKSON. HOWARD -W. RUSSELL.

US207342A 1938-05-11 1938-05-11 Induction heater construction Expired - Lifetime US2181274A (en)

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Cited By (36)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2457845A (en) * 1945-01-12 1949-01-04 Ohio Crankshaft Co Induction heating apparatus for heat-treating the interior surface of elongated small-diameter tubular workpieces
US2490106A (en) * 1945-07-04 1949-12-06 Ohio Crankshaft Co Induction heating furnace construction
US2510942A (en) * 1946-07-08 1950-06-13 Ohio Crankshaft Co Refractory and heat insulated induction heating head
US2823289A (en) * 1955-02-14 1958-02-11 American Radiator & Standard Induction heating method and apparatus
US2912553A (en) * 1957-03-14 1959-11-10 Ohio Crankshaft Co Induction muffle furnace
US3053959A (en) * 1959-12-15 1962-09-11 Richard M Christmann Apparatus and method for heating fluids
US3100250A (en) * 1961-04-07 1963-08-06 Herczog Andrew Zone melting apparatus
US3190997A (en) * 1961-02-16 1965-06-22 Transcontinental Electronics C Heating apparatus
US3260578A (en) * 1962-11-16 1966-07-12 Monsanto Co Coated induction heating coil for zone refining apparatus
US3414698A (en) * 1965-10-27 1968-12-03 Gen Electric High voltage transformer type heater for heating fluids
US3452199A (en) * 1966-05-03 1969-06-24 Bell Telephone Labor Inc Detection and utilization of heat and infrared radiation emitted by magnetic elements during magnetic reversal thereof
FR2449647A1 (en) * 1979-02-26 1980-09-19 Kestner App Evaporateurs Concentrating sulphuric acid by heating - using metallic susceptor in contact with the acid, and an induction heating coil
US4256945A (en) * 1979-08-31 1981-03-17 Iris Associates Alternating current electrically resistive heating element having intrinsic temperature control
WO1982003148A1 (en) * 1981-03-02 1982-09-16 Ass Iris Electrically resistive heating element having temperature control
WO1982003305A1 (en) * 1981-03-16 1982-09-30 Ass Iris Shielded heating element having intrinsic temperature control
FR2503974A1 (en) * 1981-04-08 1982-10-15 Masser Sa Induction heating tool holder device
US4486641A (en) * 1981-12-21 1984-12-04 Ruffini Robert S Inductor, coating and method
WO1985000263A1 (en) * 1983-06-27 1985-01-17 Metcal, Inc. Flexible autoregulating heater with a latching mechanism
US4499355A (en) * 1982-09-30 1985-02-12 Clairol Incorporated Heated personal care appliances
US4629844A (en) * 1984-08-28 1986-12-16 The Electricity Council Induction heater having an alternating current conductor
US4695713A (en) * 1982-09-30 1987-09-22 Metcal, Inc. Autoregulating, electrically shielded heater
EP0252719A1 (en) * 1986-07-07 1988-01-13 Chisso Engineering CO. LTD. Electric fluid heater
US4745264A (en) * 1984-03-06 1988-05-17 Metcal, Inc. High efficiency autoregulating heater
US4752673A (en) * 1982-12-01 1988-06-21 Metcal, Inc. Autoregulating heater
US4814587A (en) * 1986-06-10 1989-03-21 Metcal, Inc. High power self-regulating heater
US5480397A (en) * 1992-05-01 1996-01-02 Hemostatic Surgery Corporation Surgical instrument with auto-regulating heater and method of using same
US5480398A (en) * 1992-05-01 1996-01-02 Hemostatic Surgery Corporation Endoscopic instrument with disposable auto-regulating heater
EP0702504A2 (en) * 1994-09-16 1996-03-20 VEM-Elektroantriebe GmbH Thermal tube and method for induction heating of impregnated electrical assemblies
WO1996008942A1 (en) * 1994-09-16 1996-03-21 Vem-Elektroantriebe Gmbh Heat generator
US5593406A (en) * 1992-05-01 1997-01-14 Hemostatic Surgery Corporation Endoscopic instrument with auto-regulating heater and method of using same
US5611798A (en) * 1995-03-02 1997-03-18 Eggers; Philip E. Resistively heated cutting and coagulating surgical instrument
US20020125244A1 (en) * 2001-01-24 2002-09-12 Harison Toshiba Lighting Corporation Induction heating roller device, heating roller for induction heating roller device, fixing apparatus and image forming apparatus
US20050024002A1 (en) * 2003-07-31 2005-02-03 Jackson Robert D. Inductive heating system and method for controlling discharge of electric energy from machines
US20080021377A1 (en) * 2003-11-05 2008-01-24 Baxter International Inc. Dialysis fluid heating systems
US20090224523A1 (en) * 2008-03-04 2009-09-10 Hyundai Motor Company Heated steering wheel using induction current
US20100051174A1 (en) * 2008-09-01 2010-03-04 Mitsubishi Electric Corporation Connection method of thermoplastic resin long body

Cited By (48)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2457845A (en) * 1945-01-12 1949-01-04 Ohio Crankshaft Co Induction heating apparatus for heat-treating the interior surface of elongated small-diameter tubular workpieces
US2490106A (en) * 1945-07-04 1949-12-06 Ohio Crankshaft Co Induction heating furnace construction
US2510942A (en) * 1946-07-08 1950-06-13 Ohio Crankshaft Co Refractory and heat insulated induction heating head
US2823289A (en) * 1955-02-14 1958-02-11 American Radiator & Standard Induction heating method and apparatus
US2912553A (en) * 1957-03-14 1959-11-10 Ohio Crankshaft Co Induction muffle furnace
US3053959A (en) * 1959-12-15 1962-09-11 Richard M Christmann Apparatus and method for heating fluids
US3190997A (en) * 1961-02-16 1965-06-22 Transcontinental Electronics C Heating apparatus
US3100250A (en) * 1961-04-07 1963-08-06 Herczog Andrew Zone melting apparatus
US3260578A (en) * 1962-11-16 1966-07-12 Monsanto Co Coated induction heating coil for zone refining apparatus
US3414698A (en) * 1965-10-27 1968-12-03 Gen Electric High voltage transformer type heater for heating fluids
US3452199A (en) * 1966-05-03 1969-06-24 Bell Telephone Labor Inc Detection and utilization of heat and infrared radiation emitted by magnetic elements during magnetic reversal thereof
FR2449647A1 (en) * 1979-02-26 1980-09-19 Kestner App Evaporateurs Concentrating sulphuric acid by heating - using metallic susceptor in contact with the acid, and an induction heating coil
US4256945A (en) * 1979-08-31 1981-03-17 Iris Associates Alternating current electrically resistive heating element having intrinsic temperature control
US4701587A (en) * 1979-08-31 1987-10-20 Metcal, Inc. Shielded heating element having intrinsic temperature control
WO1982003148A1 (en) * 1981-03-02 1982-09-16 Ass Iris Electrically resistive heating element having temperature control
WO1982003305A1 (en) * 1981-03-16 1982-09-30 Ass Iris Shielded heating element having intrinsic temperature control
FR2503974A1 (en) * 1981-04-08 1982-10-15 Masser Sa Induction heating tool holder device
EP0063556A1 (en) * 1981-04-08 1982-10-27 Masser S.A. Inductively heated toolholder device
US4486641A (en) * 1981-12-21 1984-12-04 Ruffini Robert S Inductor, coating and method
US4499355A (en) * 1982-09-30 1985-02-12 Clairol Incorporated Heated personal care appliances
US4695713A (en) * 1982-09-30 1987-09-22 Metcal, Inc. Autoregulating, electrically shielded heater
US4752673A (en) * 1982-12-01 1988-06-21 Metcal, Inc. Autoregulating heater
US4695712A (en) * 1983-06-27 1987-09-22 Metcal, Inc. Flexible autoregulating heater with a latching mechanism
WO1985000263A1 (en) * 1983-06-27 1985-01-17 Metcal, Inc. Flexible autoregulating heater with a latching mechanism
US4745264A (en) * 1984-03-06 1988-05-17 Metcal, Inc. High efficiency autoregulating heater
US4629844A (en) * 1984-08-28 1986-12-16 The Electricity Council Induction heater having an alternating current conductor
US4814587A (en) * 1986-06-10 1989-03-21 Metcal, Inc. High power self-regulating heater
US4791262A (en) * 1986-07-07 1988-12-13 Chisso Engineering Co Ltd Voltage transformer type electric fluid heater
EP0252719A1 (en) * 1986-07-07 1988-01-13 Chisso Engineering CO. LTD. Electric fluid heater
US5480397A (en) * 1992-05-01 1996-01-02 Hemostatic Surgery Corporation Surgical instrument with auto-regulating heater and method of using same
US5480398A (en) * 1992-05-01 1996-01-02 Hemostatic Surgery Corporation Endoscopic instrument with disposable auto-regulating heater
US5593406A (en) * 1992-05-01 1997-01-14 Hemostatic Surgery Corporation Endoscopic instrument with auto-regulating heater and method of using same
EP0702504A2 (en) * 1994-09-16 1996-03-20 VEM-Elektroantriebe GmbH Thermal tube and method for induction heating of impregnated electrical assemblies
WO1996008942A1 (en) * 1994-09-16 1996-03-21 Vem-Elektroantriebe Gmbh Heat generator
DE4432978A1 (en) * 1994-09-16 1996-03-28 Vem Elektroantriebe Gmbh Thermal tube and method for inductive heating soaked, electric modules
DE4432979A1 (en) * 1994-09-16 1996-04-04 Vem Elektroantriebe Gmbh heat generator
EP0702504A3 (en) * 1994-09-16 1996-12-18 Vem Elektroantriebe Gmbh Thermal tube and method for induction heating of impregnated electrical assemblies
DE4432978C2 (en) * 1994-09-16 2001-02-08 Vem Elektroantriebe Gmbh Apparatus and method for inductive heating soaked electrical modules
US5611798A (en) * 1995-03-02 1997-03-18 Eggers; Philip E. Resistively heated cutting and coagulating surgical instrument
US20020125244A1 (en) * 2001-01-24 2002-09-12 Harison Toshiba Lighting Corporation Induction heating roller device, heating roller for induction heating roller device, fixing apparatus and image forming apparatus
US6847019B2 (en) * 2001-01-24 2005-01-25 Harison Toshiba Lighting Corporation Induction heating roller device, heating roller for induction heating roller device, fixing apparatus and image forming apparatus
US20050024002A1 (en) * 2003-07-31 2005-02-03 Jackson Robert D. Inductive heating system and method for controlling discharge of electric energy from machines
US20050040780A1 (en) * 2003-07-31 2005-02-24 Jackson Robert D. Enhanced system and method for controlling discharge of electric energy from machines
US20080021377A1 (en) * 2003-11-05 2008-01-24 Baxter International Inc. Dialysis fluid heating systems
US8803044B2 (en) * 2003-11-05 2014-08-12 Baxter International Inc. Dialysis fluid heating systems
US20090224523A1 (en) * 2008-03-04 2009-09-10 Hyundai Motor Company Heated steering wheel using induction current
US20100051174A1 (en) * 2008-09-01 2010-03-04 Mitsubishi Electric Corporation Connection method of thermoplastic resin long body
US8038818B2 (en) * 2008-09-01 2011-10-18 Mitsubishi Electric Corporation Connection method of thermoplastic resin long body

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