US3735328A - Sheathed electrical resistance heating element - Google Patents

Sheathed electrical resistance heating element Download PDF

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Publication number
US3735328A
US3735328A US00199191A US3735328DA US3735328A US 3735328 A US3735328 A US 3735328A US 00199191 A US00199191 A US 00199191A US 3735328D A US3735328D A US 3735328DA US 3735328 A US3735328 A US 3735328A
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US
United States
Prior art keywords
strip
heating
sheath
coil
heating unit
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
US00199191A
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English (en)
Inventor
M Yagi
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.)
Fujifilm Holdings Corp
Original Assignee
Fuji Photo Film Co Ltd
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 Fuji Photo Film Co Ltd filed Critical Fuji Photo Film Co Ltd
Application granted granted Critical
Publication of US3735328A publication Critical patent/US3735328A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • 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
    • H05B3/44—Heating elements having the shape of rods or tubes non-flexible heating conductor arranged within rods or tubes of insulating material

Definitions

  • ABSTRACT [30] Foreign Application prioritypaw A sheathed electrical resistance heating element consisting of a helical electrically resistant heating strip NOV. I6, 1970 Japan ..45/l00912 having Segmented portions p j g outwardly in a U 8 Cl 338/270 338/267 338/315 tangential direction along the helices of the coil strip. 338/234
  • the helical heating coil is placed in a heat resisting [51] Int Cl H01c 1/02 sheath of a transparent crystalline tube.
  • the helical 58 Field of serircii ..338/267 268, 270, heating Strip is POsitioned Within the heat resisting 33 5 234 tube by the segmented portions which project from the surface of the coil and contact the inner wall of the tube.
  • the present invention is directed particularly to electrical resistant heating elements that are to be positioned within an outer casing or sheath. More particularly, the present invention is directed to a sheath electrical resistant heating element having a helical configuration and consisting of a heat resisting electrically conducting alloy.
  • the helical configuration has a number of tangentially projecting tongues or projections for positioning the heating coil within a tubular shaft formed of a heat resistant ceramic material.
  • Previous sheathed electrical resistant heating elements generally comprised an inner helical shaped electrical heating wire formed of a heat resisting alloy and having an outer protective tubular shaft made of opaque quartz.
  • This type of heating unit is used widely in household utensils for example, in electrical stoves.
  • this type of heating unit has its helical heating element in direct contact with the inner wall surface of its sheath, and the heat from the heating element is directly given off to the tubular sheath through the contact area. Because of this particular contact, the heating element with the sheath, it generally takes a long time for the heating unit to reach a state of thermal equilibrium and thereby results in a low initial heating efficiency.
  • a further problem is encountered with this type of heating unit in that the high temperature deterioration of the tubular sheath material often occurs. Because of this reason, the surface temperature of the heating element or coil must generally be limited to relatively low temperatures.
  • One of the objects of the present invention is to provide an improved high efficiency sheathed electrical resistance heating element which can be used widely in household heating devices, such as, for example, electrical stoves and electrical toasters.
  • Another object of this invention is to provide a sheathed electrical resistance heating element which can be both small in size and light in weight and which will not be subject to high temperature deterioration of the outer casing or sheath.
  • a further object of this invention is to provide a sheathed electrical resistance heating element having a fast response time to initial heating and wherein it is possible to maintain a higher surface temperature in the heating element.
  • the present invention provides a sheathed electrical resistance heating element having a helical electrical heating strip formed of a heat resistance alloy.
  • the helical heating strip has portions of the strip which project outwardly in a direction tangential to the helices.
  • the heating strip is disposed within a heat resistant sheath, for example, a ceramic tube, and is positioned along the direction of the axis thereof.
  • the heating strip or coil may be maintained in contact with the inner wall of the tube only at those points contacting the projected tongue portions that extend tangentially from the helices.
  • FIG. 1 shows a longitudinal section of one embodiment of a sheathed electrical resistance heating element within a sheath
  • FIG. 2 shows a cross-sectional view of FIG. 1
  • FIG. 3 shows a plan view of the electrical heating strip of FIG. 1 prior to its being formed in the helices
  • FIG. 4 shows a plan view of another embodiment of the heating strip prior to its being formed in the helices
  • FIG. 5 shows a plan view of a third embodiment of a heating strip prior to its being formed in the helices.
  • a heat resisting ceramic tube 1 is disclosed with an electrical heating strip 2 wound into a helical coil form and disposed within the ceramic tube 1 along the direction of its axis.
  • the heating strip 2 is provided with cuttings 4, shown in FIG. 3, at a suitable pitch along the edge portion of the strip.
  • the projecting tongue portion 3 formed from the cutting 4 is projected outwardly in a tangential direction to the helices when the heating strip is formed into a helical shape.
  • the helical heating coil strip 2 disposed within the ceramic tube 1 is in contact with the inner wall of the tube only at those points where the projected tongue portions 3 contact the wall.
  • the helical heating coil strip of this invention will have a relatively large surface area per unit length for the same cross-sectional area, without the deteriorating heat transfer characteristics and accordingly, it is possible to make the weight of the heating device less than one half the corresponding prior art element. It is also possible to reduce the initial heat energy dissipation and thereby reduce the amount of energy required to heat the element, itself.
  • the heating strip of the present invention is not in direct contact with the inner wall of the tube, it is possible to accelerate the initial heating of the heating strip itself and to effectively utilize the thermal energy radiated from the heating strip when used in combination with a heat resisting, thermal transparent ceramic tube, such as fused quartz glass tube or a transparent crystalline glass tube, etc., that is, primary thermal radiating may be utilized effectively in the present invention.
  • a heat resisting, thermal transparent ceramic tube such as fused quartz glass tube or a transparent crystalline glass tube, etc.
  • primary thermal radiating may be utilized effectively in the present invention.
  • the heating element of the present invention is arranged so that the majority of the effective heat radiating area of the heating strip is not in direct contact with the inner wall of the sheath tube, it is accordingly possible to utilize a higher surface load den resisting alloy having a thickness of 0.01 mm and a width of 1.8 mm with an electrical resistance characteristic of 7.64Q/m.
  • the heat resisting alloy was composed of Fe-Cr-Al (25 percent chromium, percent aluminum, and 70 percent iron, as weight percent). This heat resistant alloy had a volumetric specific resistivity of l42Q/cm
  • the strip was wound on a mandrel of 3.00 mm diameter and was formed into a helical coil having a 4.0 mm diameter.
  • a sheath tube having a 9 mm outside diameter and a 1 mm thickness was formed of transparent crystalline glass.
  • the glass comprised, by weight, about 70 percent SiO 20% A1 0 3% Li O and 2% ZrO
  • the glass composition was heat treated at 850 C. for 6 hours.
  • the helical coil heating strip of the present invention was disposed within the glass tube and stretched out to a coil length of 230 mm. Both ends of the helical coil were securely clamped.
  • the electrical resistance of the resulting heat element was 9.80 at room temperature.
  • the power dissipation was 250 watts and the surface load density was 8.3 amps/cm in the heat generating area of W, (shown in FIG. 3) and 5.0 watts/cm in the area of W0.
  • the maximum surface temperature of the heating strip was 970 C. when it reached thermal equilibrium.
  • the heating strip reached a state of redness within seconds after applying the voltage, and accordingly, a quick heating response was observed.
  • the transparent crystalline glass used in this experiment had the property that it would damage change into a milky glass if it was kept at 950 C for 4 hours.
  • the heating strip without the projected tongue portions of the present invention at the same strip surface thermal density as described,
  • the transparent crystalline glass tube changed after about 20 hours into a milky glass coloration at those portions in which the heating coil strip was in contact with the inner wall of the tube. in the embodiment of this invention, as described above, however, no change was noted in the glass even after 2,000 hours of operatron.
  • heating coil cross-sectional shape other than circular, for example, square, hexagonal, octagonal, and also to. make the projected tongue portions in other shapes.
  • a sheathed electrical resistance heating unit comprising:
  • an inner heating strip formed into a coil and having portions cut therefrom and projecting from the helices of the coil to provide the sole supporting contact with said sheath intermediate the ends of said heating strip, and means for electrically connecting said heating strip to a source of electrical power.

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  • Resistance Heating (AREA)
US00199191A 1970-11-16 1971-11-16 Sheathed electrical resistance heating element Expired - Lifetime US3735328A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP45100912A JPS5027215B1 (tr) 1970-11-16 1970-11-16

Publications (1)

Publication Number Publication Date
US3735328A true US3735328A (en) 1973-05-22

Family

ID=14286533

Family Applications (1)

Application Number Title Priority Date Filing Date
US00199191A Expired - Lifetime US3735328A (en) 1970-11-16 1971-11-16 Sheathed electrical resistance heating element

Country Status (5)

Country Link
US (1) US3735328A (tr)
JP (1) JPS5027215B1 (tr)
DE (1) DE2156925A1 (tr)
FR (1) FR2114748A5 (tr)
GB (1) GB1372274A (tr)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4308080A (en) * 1979-02-07 1981-12-29 Micropore International Limited Method of shaping coils
US5155798A (en) * 1989-02-21 1992-10-13 Glenro, Inc. Quick-response quartz tube infra-red heater
US5560846A (en) * 1993-03-08 1996-10-01 Micropyretics Heaters International Robust ceramic and metal-ceramic radiant heater designs for thin heating elements and method for production
US6684659B1 (en) * 1999-05-17 2004-02-03 Matsushita Refrigeration Company Refrigerator and defrosting heater
US20040175989A1 (en) * 2001-06-01 2004-09-09 Edward Khoury Cordless base
US20050069303A1 (en) * 2003-09-25 2005-03-31 Mario Maione Hair dryers
EP1619931A1 (en) 2004-07-21 2006-01-25 LG Electronics, Inc. Carbon heater
EP1622423A1 (en) * 2004-07-27 2006-02-01 LG Electronics, Inc. Carbon heater
CN106982483A (zh) * 2017-03-01 2017-07-25 刘旭玲 一种套筒套装螺旋式电热管装置

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4137250A1 (de) * 1991-11-13 1993-05-19 Ego Elektro Blanc & Fischer Strahlungs-heizleiter, insbesondere eines elektrischen strahlungsheitzkoerpers
DE4137251A1 (de) * 1991-11-13 1993-05-19 Ego Elektro Blanc & Fischer Strahlungs-heizleiter, insbesondere eines elektrischen strahlungsheizkoerpers

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3548359A (en) * 1968-06-08 1970-12-15 Fuji Photo Film Co Ltd Electric heating element

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3548359A (en) * 1968-06-08 1970-12-15 Fuji Photo Film Co Ltd Electric heating element

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4308080A (en) * 1979-02-07 1981-12-29 Micropore International Limited Method of shaping coils
US5155798A (en) * 1989-02-21 1992-10-13 Glenro, Inc. Quick-response quartz tube infra-red heater
US5560846A (en) * 1993-03-08 1996-10-01 Micropyretics Heaters International Robust ceramic and metal-ceramic radiant heater designs for thin heating elements and method for production
US6684659B1 (en) * 1999-05-17 2004-02-03 Matsushita Refrigeration Company Refrigerator and defrosting heater
US20040175989A1 (en) * 2001-06-01 2004-09-09 Edward Khoury Cordless base
US20050069303A1 (en) * 2003-09-25 2005-03-31 Mario Maione Hair dryers
EP1619931A1 (en) 2004-07-21 2006-01-25 LG Electronics, Inc. Carbon heater
EP1622423A1 (en) * 2004-07-27 2006-02-01 LG Electronics, Inc. Carbon heater
US20060032847A1 (en) * 2004-07-27 2006-02-16 Lg Electronics Inc. Carbon heater
US7769278B2 (en) 2004-07-27 2010-08-03 Lg Electronics Inc. Carbon heater
CN1741688B (zh) * 2004-07-27 2011-05-11 Lg电子株式会社 碳加热器
CN106982483A (zh) * 2017-03-01 2017-07-25 刘旭玲 一种套筒套装螺旋式电热管装置
CN106982483B (zh) * 2017-03-01 2020-10-09 于浩 一种套筒套装螺旋式电热管装置

Also Published As

Publication number Publication date
DE2156925A1 (de) 1972-05-25
JPS5027215B1 (tr) 1975-09-05
GB1372274A (en) 1974-10-30
FR2114748A5 (tr) 1972-06-30

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