CA1166675A - Electric space heater - Google Patents
Electric space heaterInfo
- Publication number
- CA1166675A CA1166675A CA000375811A CA375811A CA1166675A CA 1166675 A CA1166675 A CA 1166675A CA 000375811 A CA000375811 A CA 000375811A CA 375811 A CA375811 A CA 375811A CA 1166675 A CA1166675 A CA 1166675A
- Authority
- CA
- Canada
- Prior art keywords
- wire
- coil
- heater
- electric
- diameter
- 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
Links
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
- 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
-
- 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
- H05B2203/00—Aspects relating to Ohmic resistive heating covered by group H05B3/00
- H05B2203/032—Heaters specially adapted for heating by radiation heating
Landscapes
- Resistance Heating (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
An electric heater for use in an electric stove or the like, includes an insulating tube such as a quartz tube, and a coiled resistance wire enclosed in the tube. The individual turns of the coil have a non-circular shape and are displaced from adjacent turns by spirally twisting the coil about the axis of the tube. This arrangement decreases the time re-quired for heating the wire to a specified temperature and improves the efficiency of heat radiation. The resistance wire can also be made of iron-chrome-aluminium alloy to lengthen its life.
An electric heater for use in an electric stove or the like, includes an insulating tube such as a quartz tube, and a coiled resistance wire enclosed in the tube. The individual turns of the coil have a non-circular shape and are displaced from adjacent turns by spirally twisting the coil about the axis of the tube. This arrangement decreases the time re-quired for heating the wire to a specified temperature and improves the efficiency of heat radiation. The resistance wire can also be made of iron-chrome-aluminium alloy to lengthen its life.
Description
1166~i7S
ELE CT RI C SPACE HEATE R
The present invention relates to an electric heater and, more particularlyJ to an ele.ctric radiant heater assembly for use as a space heater, a cooking heater or the like.
~ enerally, an electric heater disposed in front of a reflector, includes a quartz tube with an ohmic resistive element sheathed in the tube. A wire made of nickel-chrome alloy, generally ref~rred to as resistance wire, has been widely used as the element. Althou~h such wire is easy to obtain and work with, there has been the disadvantage that the wire becomes thinner as oxidation of the material of the wire proceeds, and therefore, it may be broken when a large current is a~plied. In other words, resistance wire has a relatively short lifetime. Particularly when the wire is wound into a coil, a short circuit accidentally formed between a pair of neighboring turns often results in b~rning out of the wire due to the increase of current. Furthermore, since a large portion of the periphery of the coil is held in contact with an inner sur-face of a supporting member, heat generated by the wire is transmitted to the supporting member. This heat transmission adversely delays the rise in temperature of the wire to its required level when the power is applied.
To prevent oxidation of the wire, an improved heating unit has been proposed including a hermetically sealed quartz tube filled with an inert gas, such as argon. The ohmic resistive element, ~sually tungsten wire, is sheathed in this hermetically sealed quartz tube. Since the tungsten wire reaches abo~t 2400C which is much higher than the
ELE CT RI C SPACE HEATE R
The present invention relates to an electric heater and, more particularlyJ to an ele.ctric radiant heater assembly for use as a space heater, a cooking heater or the like.
~ enerally, an electric heater disposed in front of a reflector, includes a quartz tube with an ohmic resistive element sheathed in the tube. A wire made of nickel-chrome alloy, generally ref~rred to as resistance wire, has been widely used as the element. Althou~h such wire is easy to obtain and work with, there has been the disadvantage that the wire becomes thinner as oxidation of the material of the wire proceeds, and therefore, it may be broken when a large current is a~plied. In other words, resistance wire has a relatively short lifetime. Particularly when the wire is wound into a coil, a short circuit accidentally formed between a pair of neighboring turns often results in b~rning out of the wire due to the increase of current. Furthermore, since a large portion of the periphery of the coil is held in contact with an inner sur-face of a supporting member, heat generated by the wire is transmitted to the supporting member. This heat transmission adversely delays the rise in temperature of the wire to its required level when the power is applied.
To prevent oxidation of the wire, an improved heating unit has been proposed including a hermetically sealed quartz tube filled with an inert gas, such as argon. The ohmic resistive element, ~sually tungsten wire, is sheathed in this hermetically sealed quartz tube. Since the tungsten wire reaches abo~t 2400C which is much higher than the
- 2 - s ~1166~7S
melting point ~about 1500C) of the quartz, this unit required means for supporting the tungsten wire in a position separated from the inner wall of the quartz, using, for exampIe, tantalum. This improved heating unit thus requires additional elements, such as the inert gas and the supporting means, with resulting increase in manufacturing steps and cost. Further-more, since the tungsten wire emits as much light as in a light bulb, it is inappropriate for use in room heaters and cooking heaters.
To suppress light emission from the ohmic resistive element, a heating unit employing molybdenum as the resistive element has been proposed. Although this unit suppresses~
the light emission, it generates heat at about 1400-1600C
which is still higher than the upper limit of temperature for safe use with the quartz. This unit thus also requires supporting means for the wire. Furthermore, the employment of molybdenum has the disadvantage that, if the quartz tube is accidentally broken during heat generation, the molybdenum is turned into molybdenum oxide by the air, resulting in sublimation and scattering of white molybdenum oxide powder.
To enable the prior art to be explained with the aid of diagrams, the figures of drawings will now be listed.
; Fig. 1 is a perspective view of an electric stove to which an electric heater according to the present invention may be applied, Fig. 2 is a fragmentary cross sectional view of the ; electric heater and a reflector employed in the stove of the Fig. 1, ,, I
Fig. 3 is a longitudinal sectional view of the electric heater of Fig. 1, Figs. 4~a) and 4~b) are respectively a partial perspective view of a resistance wire of the electric heater of Fig. 3 and a side elevational view of the resistance wire~
Fig. 5 is a fragmentary cross sectional view of a conventional electric heater and a reflector employed in an electric stove, Fig. 6 is a fragmentary side sectional view showing, on on an enlarged scale, the construction of the conventional electric heater of Fig. 5, Figs. 7(a) and 7(b) are respectively a side elevational view of a resistance wire of the conventional electric heater of Fig. 6 and a front elevational view of the resistance wire, Fig. 8 is a characteristic diagram showing the time required for heating the resistance wire to a specified temperature, according to the present invention and that of a conventional electric heater, and Fig. 9 is a characteristic diagram showing the efficiency of heat radiation according to the present invention and that of a conventional electric heater.
Figs. 5 and 6 show a typical prior art heater including an insulating tube 11, such as a quartz tube, and an ohmic resistive wire 12 inserted in the quartz tube 11 for gener-ating heat when electric current flows therethrough. Since the wire 12 is formed as a coil with each turn forming a com-plete circle when viewed from one end of the coil, as shown in Fig. 7a, there is the disadvantage that the area of contact between the wire 12 and the inner surface of the insulating tube 11 is quite large. As a result, heat generated by the wire 12 is transmitted to the insulating tube 11, resulting in a relatively long period of time for the desired heat radiation level to be reached after the power has been applied, ~ 66675 as shown by the dotted line in Fig. 8. Furthermore, since ~he turns in the coil are aligned with each other, as shown in Fig. 7b, the heat radiation is interferred with by neighboring turns. This undesirably reduces the free heat radiation and lowers the efficiency of such radiation as shown by the dotted line in ~ig. 9.
One form of prior art device is disclosed in U.S.
Patent No. 3,551,643 issued December 29, 1970 to Theodore J.
Pricenski, et al in which the periphery of the individual turns of the coiled resistance wire forms a cyclical, spiral shape about the axis of the heater. This arrangement produces a turbulent flow of a fluid by obstructing the axial flow of the fluid through the heater. Heat transfer from the resistance wire to the fluid is thus promoted so as to increase the temperature of the fluid flowing between two cyiinders. This U.S. patent discloses a method of utilizing the conduction heat efficiently with the temperature of the resistance wire exceeding 1000C. Although this U.S. patent can be effectively applied to heat exchange by means of a fluid such as a gas flowing through a quartz tube, it discloses neither efficient heat radiation by disposing the electric heater in front of a reflector nor an effective and economical heater through a full understanding of the life in terms of oxidation, and the relations among the wire material, wire diameter, and coil pitch.
Accordingly, the present invention provides an improved electric space heater comprising a reflector and a radiant heating element, said element comprising an arrangement in which a coiled resistance wire is enclosed in an insulating tube, such as a quartz tube, the individual turns of the coil having a non-circular shape and being displaced from adjacent turns by spirally twisting the coil about the axis of the tube so as to decrease the time required for ~16~i67S
heating the resistance wire to a specified temperature and improving the efficiency of heat radiation.
In a preferred embodiment of the present invention the resistance wire is made of an iron-chrome-aluminium alloy so as to lengthen its life.
.
DETAILED DESCRIPTION OF ~HE EMBODI~IENTS OF THE INVENT~ON
Referring now to the drawings, there is shown in Figs. 1 and 2 electric heaters 3 according to one preferred embodiment of the present invention disposed in front of a reflector 2 provided on a frame 1 of an electric stove, the heaters 3 being supported at opposite ends thereof by side walls of the frame 1. Each heater has an insulating tube 4 such as a quartz tube and a resistance wire 5 enclosed in the tube 4.
The resistance wire 5 is made of an iron-chrome-aluminium alloy. As a result aluminium contained therein is deposited on the surface of the wire 5 to form a film of aluminium oxide. Accordingly, the iron and chrome contained therein are protected from the atmosphere and thws less likely to be subjected to oxidation. In this way the life of the heater 3 is improved and the surface of the resistance wire 5 is electrically insulated.
As shown in Figs. 4(a) and ~b), the resistance wire 5 is wound in the shape of a coil, the individual turns of which have a non-circular shape and are radially displaced from adjacent turns by spirally twisting the coil about the axis of the heater. When the resistance wire 5 so formed is inserted into the insulating tube 4, as shown in Fig. 2,one end of some turns of the non-circular coiled wire 5 come into con-tact at their peripheral portions or tips with the innersurface of the insulating tube 4, while other turns thereof iS7~
do not make such contact. Since the wire 5 has been sequent-ially twisted about the axis of the heater, the contact portions between the wire 5 and the inner surface of the insulating tube 4 are staggered with respect to the axis of the insulating tube 4. By sequentially twisting a non-circular coiled wire as described above, it is not all turns of the resistance wire 5 that contact the inner surface of the insulating tube 4, but some turns are spaced therefrom by certain distances, as most clearly seen in Fig. 3. This is in contrast with a conventional circular coiled wire, and results in a decrease in the contact area between the wire 5 and the inner surface of the insulating tube 4.
Meanwhile, due to its non-circular profile, the apparent outer diameter D, Fig. 4~a), of the coil of the wire 5 can be made, for example, 1.5 times as large as an outer diameter a of a conventional circular coil shown i.n Fig. 6. ~lence the time required for heating the wire 5 to a specifi.ed temperature can be decreased to approximately half of that of a conventional circular coiled resistance wire, 2() as shown by the solid line in Fig. 8.
Since adjacent turns of the coil of the spirally twisted wire 5 are non-aligned with each other with respect to the axis of the tube 4, interference with the heat energy enlitted by individual turns of the coll, which can result :in an abnormal rise in the temperature of the wire in a conventional coil, is substantially reduced. Furthermore, since the radiant heat emitted from the wire S is diffused at a wide angle, partly due to the apparent increase in the coil diameter as described above, the radiant heat energy of the present construction, shown by the solid line in Fig. 9 is improved by 10 to 15 % as compared with that of the conventional wire shown by the dotted line in Fig. 9.
il~6675 An elliptical colled wire 5 provides~smoother bending portions as compared with the rectangular coil disclosed in the U.S. patent described earlier and thus it is less likely to be broken due to internal stress during manufacture. The life of the wire can thus be improved.
The present inventors have prepared various samples and have conducted thorough life tests and power supply tests thereof. The results of these tests have shown that a resistance wire manufactured under the following conditions is especially suitable for an electric heater for use in electric stoves, cooking ovens and the like. Ten iron chrome-aluminium alloy resistance wires 5 of 0.4 to 0.6 mm in diameter,with a power consumption of 800 W were used for these tests. The relation between the wire diameter d and the coil diameter D, as shown in Fig. 4, provides the longest life thereof and most efficient heat radiation when expressed by: lOd< D < lSd. If the coil diameter D exceeds 15d, each turn of the coil has to be so tilted in the axial direction as to cause contact between adjacent turns, resulting in a short circuit between turns and ultimate rupture of the wire. If the coil diameter D is less than lOd, more significant heat interference takes place between adjacent turns of the coil, resulting in heat being accumulated in the vicinity of the wire, so that radiant heat to be emitted from the heater is reduced. Also manufacture of such a coil is more difficult.
In an electric stove, when the resistance wire is red hot to utilize the radiant heat efficiently, a wire temperature of ~00 to 950C is typical.
The relation between the coil diameter D and the twisting pitch P of the spirally twisted resistance wire 5 :li6~i~i75 provides longest life thereof and most rapid heating of the stove when expressed by : SD < P < 7D. If the twisting pitch P exceeds 7D, such large pitch slackens the coil between each pitch and the contact area between the wire 5 and the inner surface of the insulating tube ~ is undesirably increased, resulting in a larger part of the radiant heat emitted from the wire 5 being transferred to the tube ~ at start up with consequent deterioration in the rapid heating required by electric stoves. If the twisting pitch P is ]ess than 5D, the contact area between the wire 5 and the inner surface of the insulating tube 4 is increased as in the case above, so that rapid heating is again deteriorated.
The relation between the wire diameter d and the pitch P' between adjacent turns of the coil is most suitable when expressed by: P' = 2 to 3d. Since the apparent diameter of the non-circular coil of the present construction can be made larger than that of a con-ventional circular coil, the overall axial length of the heater of the present construction can be made approximately half that of a conventional one, for both heaters to have the same calorific value. If both heaters have the same overall axial length, the pitch P' between adjacent turns of the coil of the present construction can be increased by S0~ as compared with a conventional coil.
Although the present invention has been fully described by way of embodiments illustrated in the accompanying draw-ings, it is to be noted that various changes and modifications will be apparent to those skilled in the art. Therefore, unless such changes and modifications depart from the scope of the present invention as defined in the claims, they should be construed as included therein.
g _
melting point ~about 1500C) of the quartz, this unit required means for supporting the tungsten wire in a position separated from the inner wall of the quartz, using, for exampIe, tantalum. This improved heating unit thus requires additional elements, such as the inert gas and the supporting means, with resulting increase in manufacturing steps and cost. Further-more, since the tungsten wire emits as much light as in a light bulb, it is inappropriate for use in room heaters and cooking heaters.
To suppress light emission from the ohmic resistive element, a heating unit employing molybdenum as the resistive element has been proposed. Although this unit suppresses~
the light emission, it generates heat at about 1400-1600C
which is still higher than the upper limit of temperature for safe use with the quartz. This unit thus also requires supporting means for the wire. Furthermore, the employment of molybdenum has the disadvantage that, if the quartz tube is accidentally broken during heat generation, the molybdenum is turned into molybdenum oxide by the air, resulting in sublimation and scattering of white molybdenum oxide powder.
To enable the prior art to be explained with the aid of diagrams, the figures of drawings will now be listed.
; Fig. 1 is a perspective view of an electric stove to which an electric heater according to the present invention may be applied, Fig. 2 is a fragmentary cross sectional view of the ; electric heater and a reflector employed in the stove of the Fig. 1, ,, I
Fig. 3 is a longitudinal sectional view of the electric heater of Fig. 1, Figs. 4~a) and 4~b) are respectively a partial perspective view of a resistance wire of the electric heater of Fig. 3 and a side elevational view of the resistance wire~
Fig. 5 is a fragmentary cross sectional view of a conventional electric heater and a reflector employed in an electric stove, Fig. 6 is a fragmentary side sectional view showing, on on an enlarged scale, the construction of the conventional electric heater of Fig. 5, Figs. 7(a) and 7(b) are respectively a side elevational view of a resistance wire of the conventional electric heater of Fig. 6 and a front elevational view of the resistance wire, Fig. 8 is a characteristic diagram showing the time required for heating the resistance wire to a specified temperature, according to the present invention and that of a conventional electric heater, and Fig. 9 is a characteristic diagram showing the efficiency of heat radiation according to the present invention and that of a conventional electric heater.
Figs. 5 and 6 show a typical prior art heater including an insulating tube 11, such as a quartz tube, and an ohmic resistive wire 12 inserted in the quartz tube 11 for gener-ating heat when electric current flows therethrough. Since the wire 12 is formed as a coil with each turn forming a com-plete circle when viewed from one end of the coil, as shown in Fig. 7a, there is the disadvantage that the area of contact between the wire 12 and the inner surface of the insulating tube 11 is quite large. As a result, heat generated by the wire 12 is transmitted to the insulating tube 11, resulting in a relatively long period of time for the desired heat radiation level to be reached after the power has been applied, ~ 66675 as shown by the dotted line in Fig. 8. Furthermore, since ~he turns in the coil are aligned with each other, as shown in Fig. 7b, the heat radiation is interferred with by neighboring turns. This undesirably reduces the free heat radiation and lowers the efficiency of such radiation as shown by the dotted line in ~ig. 9.
One form of prior art device is disclosed in U.S.
Patent No. 3,551,643 issued December 29, 1970 to Theodore J.
Pricenski, et al in which the periphery of the individual turns of the coiled resistance wire forms a cyclical, spiral shape about the axis of the heater. This arrangement produces a turbulent flow of a fluid by obstructing the axial flow of the fluid through the heater. Heat transfer from the resistance wire to the fluid is thus promoted so as to increase the temperature of the fluid flowing between two cyiinders. This U.S. patent discloses a method of utilizing the conduction heat efficiently with the temperature of the resistance wire exceeding 1000C. Although this U.S. patent can be effectively applied to heat exchange by means of a fluid such as a gas flowing through a quartz tube, it discloses neither efficient heat radiation by disposing the electric heater in front of a reflector nor an effective and economical heater through a full understanding of the life in terms of oxidation, and the relations among the wire material, wire diameter, and coil pitch.
Accordingly, the present invention provides an improved electric space heater comprising a reflector and a radiant heating element, said element comprising an arrangement in which a coiled resistance wire is enclosed in an insulating tube, such as a quartz tube, the individual turns of the coil having a non-circular shape and being displaced from adjacent turns by spirally twisting the coil about the axis of the tube so as to decrease the time required for ~16~i67S
heating the resistance wire to a specified temperature and improving the efficiency of heat radiation.
In a preferred embodiment of the present invention the resistance wire is made of an iron-chrome-aluminium alloy so as to lengthen its life.
.
DETAILED DESCRIPTION OF ~HE EMBODI~IENTS OF THE INVENT~ON
Referring now to the drawings, there is shown in Figs. 1 and 2 electric heaters 3 according to one preferred embodiment of the present invention disposed in front of a reflector 2 provided on a frame 1 of an electric stove, the heaters 3 being supported at opposite ends thereof by side walls of the frame 1. Each heater has an insulating tube 4 such as a quartz tube and a resistance wire 5 enclosed in the tube 4.
The resistance wire 5 is made of an iron-chrome-aluminium alloy. As a result aluminium contained therein is deposited on the surface of the wire 5 to form a film of aluminium oxide. Accordingly, the iron and chrome contained therein are protected from the atmosphere and thws less likely to be subjected to oxidation. In this way the life of the heater 3 is improved and the surface of the resistance wire 5 is electrically insulated.
As shown in Figs. 4(a) and ~b), the resistance wire 5 is wound in the shape of a coil, the individual turns of which have a non-circular shape and are radially displaced from adjacent turns by spirally twisting the coil about the axis of the heater. When the resistance wire 5 so formed is inserted into the insulating tube 4, as shown in Fig. 2,one end of some turns of the non-circular coiled wire 5 come into con-tact at their peripheral portions or tips with the innersurface of the insulating tube 4, while other turns thereof iS7~
do not make such contact. Since the wire 5 has been sequent-ially twisted about the axis of the heater, the contact portions between the wire 5 and the inner surface of the insulating tube 4 are staggered with respect to the axis of the insulating tube 4. By sequentially twisting a non-circular coiled wire as described above, it is not all turns of the resistance wire 5 that contact the inner surface of the insulating tube 4, but some turns are spaced therefrom by certain distances, as most clearly seen in Fig. 3. This is in contrast with a conventional circular coiled wire, and results in a decrease in the contact area between the wire 5 and the inner surface of the insulating tube 4.
Meanwhile, due to its non-circular profile, the apparent outer diameter D, Fig. 4~a), of the coil of the wire 5 can be made, for example, 1.5 times as large as an outer diameter a of a conventional circular coil shown i.n Fig. 6. ~lence the time required for heating the wire 5 to a specifi.ed temperature can be decreased to approximately half of that of a conventional circular coiled resistance wire, 2() as shown by the solid line in Fig. 8.
Since adjacent turns of the coil of the spirally twisted wire 5 are non-aligned with each other with respect to the axis of the tube 4, interference with the heat energy enlitted by individual turns of the coll, which can result :in an abnormal rise in the temperature of the wire in a conventional coil, is substantially reduced. Furthermore, since the radiant heat emitted from the wire S is diffused at a wide angle, partly due to the apparent increase in the coil diameter as described above, the radiant heat energy of the present construction, shown by the solid line in Fig. 9 is improved by 10 to 15 % as compared with that of the conventional wire shown by the dotted line in Fig. 9.
il~6675 An elliptical colled wire 5 provides~smoother bending portions as compared with the rectangular coil disclosed in the U.S. patent described earlier and thus it is less likely to be broken due to internal stress during manufacture. The life of the wire can thus be improved.
The present inventors have prepared various samples and have conducted thorough life tests and power supply tests thereof. The results of these tests have shown that a resistance wire manufactured under the following conditions is especially suitable for an electric heater for use in electric stoves, cooking ovens and the like. Ten iron chrome-aluminium alloy resistance wires 5 of 0.4 to 0.6 mm in diameter,with a power consumption of 800 W were used for these tests. The relation between the wire diameter d and the coil diameter D, as shown in Fig. 4, provides the longest life thereof and most efficient heat radiation when expressed by: lOd< D < lSd. If the coil diameter D exceeds 15d, each turn of the coil has to be so tilted in the axial direction as to cause contact between adjacent turns, resulting in a short circuit between turns and ultimate rupture of the wire. If the coil diameter D is less than lOd, more significant heat interference takes place between adjacent turns of the coil, resulting in heat being accumulated in the vicinity of the wire, so that radiant heat to be emitted from the heater is reduced. Also manufacture of such a coil is more difficult.
In an electric stove, when the resistance wire is red hot to utilize the radiant heat efficiently, a wire temperature of ~00 to 950C is typical.
The relation between the coil diameter D and the twisting pitch P of the spirally twisted resistance wire 5 :li6~i~i75 provides longest life thereof and most rapid heating of the stove when expressed by : SD < P < 7D. If the twisting pitch P exceeds 7D, such large pitch slackens the coil between each pitch and the contact area between the wire 5 and the inner surface of the insulating tube ~ is undesirably increased, resulting in a larger part of the radiant heat emitted from the wire 5 being transferred to the tube ~ at start up with consequent deterioration in the rapid heating required by electric stoves. If the twisting pitch P is ]ess than 5D, the contact area between the wire 5 and the inner surface of the insulating tube 4 is increased as in the case above, so that rapid heating is again deteriorated.
The relation between the wire diameter d and the pitch P' between adjacent turns of the coil is most suitable when expressed by: P' = 2 to 3d. Since the apparent diameter of the non-circular coil of the present construction can be made larger than that of a con-ventional circular coil, the overall axial length of the heater of the present construction can be made approximately half that of a conventional one, for both heaters to have the same calorific value. If both heaters have the same overall axial length, the pitch P' between adjacent turns of the coil of the present construction can be increased by S0~ as compared with a conventional coil.
Although the present invention has been fully described by way of embodiments illustrated in the accompanying draw-ings, it is to be noted that various changes and modifications will be apparent to those skilled in the art. Therefore, unless such changes and modifications depart from the scope of the present invention as defined in the claims, they should be construed as included therein.
g _
Claims (10)
1. An electric space heater comprising a reflector and a radiant heating element, said element comprising:
an insulating tube; and a coiled resistance wire occupying the interior of said tube;
said coil having individual turns that are of non-circular shape and are displaced from adjacent turns by spirally twisting said coil about the axis of said tube.
an insulating tube; and a coiled resistance wire occupying the interior of said tube;
said coil having individual turns that are of non-circular shape and are displaced from adjacent turns by spirally twisting said coil about the axis of said tube.
2. An electric space heater as claimed in claim 1, wherein said turns are elliptical.
3. An electric space heater as claimed in claim 1, wherein the coil diameter of said wire is 10 to 15 times the diameter of said wire, said wire being adapted to be heated to temperatures ranging from approximately 800 to 1000°C
during normal use.
during normal use.
4. An electric space heater as claimed in claim 1, 2 or 3, wherein the twisting pitch of said wire is 5 to 7 times the coil diameter of said wire.
5. An electric space heater as claimed in claim 1, 2 or 3, wherein the pitch between adjacent turns of said coil is 2 to 3 times the diameter of the wire.
6. An electric space heater as claimed in claim 1, wherein said wire is made of iron-chrome-aluminum alloy.
7. An electric heater as claimed in claim 6, wherein said non-circular shape is elliptical.
8. An electric heater as claimed in claim 6, wherein the coil diameter of said wire is 10 to 15 times the diameter of said wire, said wire being adapted to be heated to temperatures ranging from approximately 800 to 1000°C
during normal use.
during normal use.
9. An electric heater as claimed in claim 6, 7 or 8, wherein the twisting pitch of said wire is 5 to 7 times the coil diameter of said wire.
10. An electric heater as claimed in claim 6, 7 or 8, wherein the pitch between adjacent turns of said coil is 2 to 3 times the diameter of the wire.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5486280U JPS56156297U (en) | 1980-04-21 | 1980-04-21 | |
| JP54862/1980 | 1980-04-21 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1166675A true CA1166675A (en) | 1984-05-01 |
Family
ID=12982392
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000375811A Expired CA1166675A (en) | 1980-04-21 | 1981-04-21 | Electric space heater |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JPS56156297U (en) |
| AU (1) | AU541773B2 (en) |
| CA (1) | CA1166675A (en) |
| GB (1) | GB2074828B (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3509985A1 (en) * | 1985-03-20 | 1986-10-02 | Kanthal GmbH, 6082 Mörfelden-Walldorf | Electrical resistance heating element |
| DE3911761A1 (en) * | 1989-04-11 | 1990-10-18 | Ako Werke Gmbh & Co | RADIATION HEATING DEVICE |
| DE4137251A1 (en) * | 1991-11-13 | 1993-05-19 | Ego Elektro Blanc & Fischer | Electric radiation heating element for ceramic cooking hob |
| DE9218244U1 (en) * | 1991-11-13 | 1993-09-23 | E.G.O. Elektro-Geräte Blanc u. Fischer, 75038 Oberderdingen | RADIATION HEATER, ESPECIALLY AN ELECTRIC RADIATION HEATER |
| DE4137250A1 (en) * | 1991-11-13 | 1993-05-19 | Ego Elektro Blanc & Fischer | Electric radiation heating element for ceramic cooking hob |
| CN105934004A (en) * | 2016-06-27 | 2016-09-07 | 镇江市春鹏电器有限公司 | Electric heating tube |
| IT202200016980A1 (en) * | 2022-08-08 | 2024-02-08 | Sacmi | ATOMIZER FOR THE PRODUCTION OF ATOMISED CERAMIC POWDER FROM AN AQUEOUS SUSPENSION OF CERAMIC MATERIAL |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5347043A (en) * | 1976-10-12 | 1978-04-27 | Matsushita Electric Ind Co Ltd | Infrared ray lamp |
-
1980
- 1980-04-21 JP JP5486280U patent/JPS56156297U/ja active Pending
-
1981
- 1981-04-16 AU AU69622/81A patent/AU541773B2/en not_active Ceased
- 1981-04-21 CA CA000375811A patent/CA1166675A/en not_active Expired
- 1981-04-21 GB GB8112281A patent/GB2074828B/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| GB2074828B (en) | 1984-01-25 |
| AU6962281A (en) | 1981-10-29 |
| GB2074828A (en) | 1981-11-04 |
| AU541773B2 (en) | 1985-01-17 |
| JPS56156297U (en) | 1981-11-21 |
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