CA2156085A1 - Heating element of electric heater - Google Patents
Heating element of electric heaterInfo
- Publication number
- CA2156085A1 CA2156085A1 CA 2156085 CA2156085A CA2156085A1 CA 2156085 A1 CA2156085 A1 CA 2156085A1 CA 2156085 CA2156085 CA 2156085 CA 2156085 A CA2156085 A CA 2156085A CA 2156085 A1 CA2156085 A1 CA 2156085A1
- Authority
- CA
- Canada
- Prior art keywords
- envelope
- heating element
- heating
- heating apparatus
- mass
- 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.)
- Abandoned
Links
Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F7/00—Heating or cooling appliances for medical or therapeutic treatment of the human body
- A61F7/007—Heating or cooling appliances for medical or therapeutic treatment of the human body characterised by electric heating
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F7/00—Heating or cooling appliances for medical or therapeutic treatment of the human body
- A61F2007/0001—Body part
Landscapes
- Health & Medical Sciences (AREA)
- Engineering & Computer Science (AREA)
- Biomedical Technology (AREA)
- Heart & Thoracic Surgery (AREA)
- Vascular Medicine (AREA)
- Life Sciences & Earth Sciences (AREA)
- Animal Behavior & Ethology (AREA)
- General Health & Medical Sciences (AREA)
- Public Health (AREA)
- Veterinary Medicine (AREA)
- Resistance Heating (AREA)
Abstract
The weight and area of the cover and of the heater in the heating element are based on a function which permits a many-fold reduction in the thickness of the heating element. The material used for the heater is copper wire.
Description
HEATING ELEMENT OF ELECTRICAL HEATER
Technical field The present invention relates to instruments for physiotherapy, namely - the heating element of an electrical heater usable for local heating to a temperature not exceeding 45C and intended for the therapeutical treatment of various diseases for instance, in rhinolaryngology.
Prior art The main element of currently known electrical heaters is a heating element adapted to be connected to a current source, said heating element being substantially an envelope, usually flat, which accommodates an electric heating apparatus made from conducting material generally insulated wire (US Patent No. 4614189, nat. cl. 128 - 380, 1984; G.B. Patent No.
1038891,1CI A61F 7/00, 1986). Said wire is represented by constantan, manganin or Ni-Cr alloy which show a relatively high specific resistance of 0,49, 0,43 and 1.1 ohm.mm2/m, respectively, and considerable elasticity.
These indices negatively affect the operation characteristics of the heating element and adaptability to manufacture thereof, especially in making miniature heating elements designed for the initial heating of limited portions. For example, during manufacture there arise, due to elasticity inherent in said materials, difficulties in forming the heating apparatus, and what is more, highly complicated is a uniform distribution of wire forming this heating apparatus in the body of the envelope of the heating element.
Irregularity of the wire distributed results in local overheatings, thus worsening said operation characteristics, reducing the operating life. For the manufacture of miniature heating elements and reducing their cost of manufacture it is desirable to use wires having the minimum cross section, and along with this, given such small cross sections there originates the danger of overheating, because of a high resistance of wires, and also of fusion or failure of said heating element envelope. For avoiding such overheating, use is made of a heat resistant heat insulated material, usually asbestos, a factor that brings about the increased overall dimensions and mass of the heating element. So, one has to admit that conventional heating elements have a rather low coefficient of heat transfer per unit mass of the heating element.
And it should be noted that the use of wires of said materials with a special heat-insulating coat, say, special varnish did not contribute to achieving satisfactory results because of unreliable coating due to the bad adhesion of this coating with said materials of wire.
Essence of the invention It is the principal object of the present invention to select such parameters of a heating apparatus and the envelope of a heating element that this heating element has a higher coefficient of heat transfer per unit mass than available heating elements and is more adaptable to streamline production as well.
The tast set is solved owing to the fact that the heating element having an envelope and a heating apparatus accommodated therein according to the invention, the mass and area of the envelope and heating apparatus are selected from the ratio:
mH = k mO and SH = (O- 8 O. 9) SO~
CA~ 1 56085 wherein mH - mass of a heating apparatus, mO - mass of an envelope, SH - area of a conductor of the heating apparatus, S0 - area of one surface of the envelope and - the coefficient of heat transfer of the material of the envelope k - (0.1 - 0.3) mC/W.
And an electric current conductor is made from plastic material having specific resistance not exceeding 0.02 ohm.mm2/m, say, copper.
If the area of a heating apparatus is below 0.8 of the area of an envelope, no warm-up is ensured up to the required temperature and if it is over 0.9 of the area of the envelope, adaptability to streamlined manufacture is upset. With "k" less than 0.1 the required heating up is not assured, and if this value exceeds 0.3 no even warm-up is provided.
With such an embodiment of a heating element, the necessity falls away in the provision of special heat insulating elements and the thickness of such heating elements can be only 2 - 5 mm, which is remarkably less than that of the existing heating elements having a thickness of about 10 mm for the same heating temperature, for instance, up to 45C. Such a considerable decrease of overall dimensions greatly expands the range of use of the heating elements.
The claimed heating element enables one to utilize a heating apparatus formed arbitrarily and even by the wires of the apparatus placed in disorder, which makes it possible to easily manufacture heating elements of a variegated hermetic configuration: round, square, elongated, etc, which likewise markedly enlarges the possibilities of use of the heating element.
And last but not least, remarkably simplified is production process of the heating element, since the wire of the heating apparatus is distributed within the envelope easily and simply, which can be produced by compression moulding, injection moulding, etc.
Summary of the drawings The present invention is further elucidated by a description of a concrete but not restricting variant of the realization of the invention and by the drawing schematically showing a heating element with a partially removed envelope.
Embodiment of the invention A heating element designated I as a whole comprises an envelope 2 and a heating apparatus 3 accommodated in this envelope. The heating apparatus is made of an insulated wire and connected with a cord (not shown) to be connected to a power source. Though the envelope 2 is shown on the drawing in the form of a disk, it, nevertheless, may have other forms, say, a cube, ring, to mention just a few. The material used for the manufacture of the envelope can be represented by any material already known for use of electrical heaters. In particular, for the material of said envelope one can use high-pressure ethylene (HPPE). As the wire of a heating apparatus we utilized copper wires having a resistivity of 0.0175 ohm. mm2/m and insulating coating from non-conducting varnish. This wire is extremely plastic and its placement in the envelope of any configuration presents no difficulties whatever.
Heating elements are known to provide heating in a range of up to 45C and we have established that the most favourable conditions of heat transfer of a heating element are secured with the following ratio of the mass and areas of an envelope and heating apparatus:
mH = k mo, wherein: mO - envelope mass mH - heating apparatus mass - coefficient of heat transfer of the material of the envelope, k = ( 0. 1 - 0.3 ) mC/W
SH= ( 0.8 - 0.9 )0, where SH - area of a heating apparatus conductor Do~ area of one surface of the envelope.
Knowing of the material for the manufacture of the envelope of a heating element and considering the latter's intended purpose, which makes it possible to specify its area and thickness one can easily determine the mass of the heating element and its area, whereby to calculate the diameter and length of the wire.
It has been established cooper can be substituted with other materials, but whatever the case, specific resistance shouldn't exceed 0.2 ohm.mm2/m, in as much as with the said ratios of masses and areas of an envelope and heating apparatus, the required temperature conditions fail.
The claimed heating element is adapted to streamlined manufacture: a heating element can easily be formed and distributed inside an envelope, in a disordered form (no strict determination of the form of the heating element is required), since the rigidity characteristics of an insulated wire of plasticmaterials allow its repeated bending and the mechanical contact on separate parts thereof. The envelope can be produced by casting this or that plastic, simultaneously disposing therein the heating element as an insert.
A comparison of the claimed heating element of a heater with the prior art taken as prototype goes to show that the claimed element has improved operating characteristics: a comparatively larger surface of heat radiation with a small mass of the heating element; the great uniformity of radiation with a low supply voltage; a comparatively high service life explained by the uniformity of radiation by the surface of the body of the element. Besides, the construction of the claimed heating element is more adaptable to streamlined manufacture as permitting using the material of the envelope represented by plastic masses having a comparatively low heat transfer which well yield to compression moulding, injection moulding and as the materials of the wire of the heating element of plastic material with low resistivity .
The construction provides for the presence of not only a thermal but also a magnetic field, which increases a medical effect (low electric resistance, a comparatively strong current, the high level of a magnetic field) .
Technical field The present invention relates to instruments for physiotherapy, namely - the heating element of an electrical heater usable for local heating to a temperature not exceeding 45C and intended for the therapeutical treatment of various diseases for instance, in rhinolaryngology.
Prior art The main element of currently known electrical heaters is a heating element adapted to be connected to a current source, said heating element being substantially an envelope, usually flat, which accommodates an electric heating apparatus made from conducting material generally insulated wire (US Patent No. 4614189, nat. cl. 128 - 380, 1984; G.B. Patent No.
1038891,1CI A61F 7/00, 1986). Said wire is represented by constantan, manganin or Ni-Cr alloy which show a relatively high specific resistance of 0,49, 0,43 and 1.1 ohm.mm2/m, respectively, and considerable elasticity.
These indices negatively affect the operation characteristics of the heating element and adaptability to manufacture thereof, especially in making miniature heating elements designed for the initial heating of limited portions. For example, during manufacture there arise, due to elasticity inherent in said materials, difficulties in forming the heating apparatus, and what is more, highly complicated is a uniform distribution of wire forming this heating apparatus in the body of the envelope of the heating element.
Irregularity of the wire distributed results in local overheatings, thus worsening said operation characteristics, reducing the operating life. For the manufacture of miniature heating elements and reducing their cost of manufacture it is desirable to use wires having the minimum cross section, and along with this, given such small cross sections there originates the danger of overheating, because of a high resistance of wires, and also of fusion or failure of said heating element envelope. For avoiding such overheating, use is made of a heat resistant heat insulated material, usually asbestos, a factor that brings about the increased overall dimensions and mass of the heating element. So, one has to admit that conventional heating elements have a rather low coefficient of heat transfer per unit mass of the heating element.
And it should be noted that the use of wires of said materials with a special heat-insulating coat, say, special varnish did not contribute to achieving satisfactory results because of unreliable coating due to the bad adhesion of this coating with said materials of wire.
Essence of the invention It is the principal object of the present invention to select such parameters of a heating apparatus and the envelope of a heating element that this heating element has a higher coefficient of heat transfer per unit mass than available heating elements and is more adaptable to streamline production as well.
The tast set is solved owing to the fact that the heating element having an envelope and a heating apparatus accommodated therein according to the invention, the mass and area of the envelope and heating apparatus are selected from the ratio:
mH = k mO and SH = (O- 8 O. 9) SO~
CA~ 1 56085 wherein mH - mass of a heating apparatus, mO - mass of an envelope, SH - area of a conductor of the heating apparatus, S0 - area of one surface of the envelope and - the coefficient of heat transfer of the material of the envelope k - (0.1 - 0.3) mC/W.
And an electric current conductor is made from plastic material having specific resistance not exceeding 0.02 ohm.mm2/m, say, copper.
If the area of a heating apparatus is below 0.8 of the area of an envelope, no warm-up is ensured up to the required temperature and if it is over 0.9 of the area of the envelope, adaptability to streamlined manufacture is upset. With "k" less than 0.1 the required heating up is not assured, and if this value exceeds 0.3 no even warm-up is provided.
With such an embodiment of a heating element, the necessity falls away in the provision of special heat insulating elements and the thickness of such heating elements can be only 2 - 5 mm, which is remarkably less than that of the existing heating elements having a thickness of about 10 mm for the same heating temperature, for instance, up to 45C. Such a considerable decrease of overall dimensions greatly expands the range of use of the heating elements.
The claimed heating element enables one to utilize a heating apparatus formed arbitrarily and even by the wires of the apparatus placed in disorder, which makes it possible to easily manufacture heating elements of a variegated hermetic configuration: round, square, elongated, etc, which likewise markedly enlarges the possibilities of use of the heating element.
And last but not least, remarkably simplified is production process of the heating element, since the wire of the heating apparatus is distributed within the envelope easily and simply, which can be produced by compression moulding, injection moulding, etc.
Summary of the drawings The present invention is further elucidated by a description of a concrete but not restricting variant of the realization of the invention and by the drawing schematically showing a heating element with a partially removed envelope.
Embodiment of the invention A heating element designated I as a whole comprises an envelope 2 and a heating apparatus 3 accommodated in this envelope. The heating apparatus is made of an insulated wire and connected with a cord (not shown) to be connected to a power source. Though the envelope 2 is shown on the drawing in the form of a disk, it, nevertheless, may have other forms, say, a cube, ring, to mention just a few. The material used for the manufacture of the envelope can be represented by any material already known for use of electrical heaters. In particular, for the material of said envelope one can use high-pressure ethylene (HPPE). As the wire of a heating apparatus we utilized copper wires having a resistivity of 0.0175 ohm. mm2/m and insulating coating from non-conducting varnish. This wire is extremely plastic and its placement in the envelope of any configuration presents no difficulties whatever.
Heating elements are known to provide heating in a range of up to 45C and we have established that the most favourable conditions of heat transfer of a heating element are secured with the following ratio of the mass and areas of an envelope and heating apparatus:
mH = k mo, wherein: mO - envelope mass mH - heating apparatus mass - coefficient of heat transfer of the material of the envelope, k = ( 0. 1 - 0.3 ) mC/W
SH= ( 0.8 - 0.9 )0, where SH - area of a heating apparatus conductor Do~ area of one surface of the envelope.
Knowing of the material for the manufacture of the envelope of a heating element and considering the latter's intended purpose, which makes it possible to specify its area and thickness one can easily determine the mass of the heating element and its area, whereby to calculate the diameter and length of the wire.
It has been established cooper can be substituted with other materials, but whatever the case, specific resistance shouldn't exceed 0.2 ohm.mm2/m, in as much as with the said ratios of masses and areas of an envelope and heating apparatus, the required temperature conditions fail.
The claimed heating element is adapted to streamlined manufacture: a heating element can easily be formed and distributed inside an envelope, in a disordered form (no strict determination of the form of the heating element is required), since the rigidity characteristics of an insulated wire of plasticmaterials allow its repeated bending and the mechanical contact on separate parts thereof. The envelope can be produced by casting this or that plastic, simultaneously disposing therein the heating element as an insert.
A comparison of the claimed heating element of a heater with the prior art taken as prototype goes to show that the claimed element has improved operating characteristics: a comparatively larger surface of heat radiation with a small mass of the heating element; the great uniformity of radiation with a low supply voltage; a comparatively high service life explained by the uniformity of radiation by the surface of the body of the element. Besides, the construction of the claimed heating element is more adaptable to streamlined manufacture as permitting using the material of the envelope represented by plastic masses having a comparatively low heat transfer which well yield to compression moulding, injection moulding and as the materials of the wire of the heating element of plastic material with low resistivity .
The construction provides for the presence of not only a thermal but also a magnetic field, which increases a medical effect (low electric resistance, a comparatively strong current, the high level of a magnetic field) .
Claims
C L A I M S:
The heating element of an electric heater, comprising an envelope with a heating apparatus disposed therein in the form of an electric insulated conductor of electric current, characterized in that the mass and area of the heating apparatus and the envelope have the ratio of:
mH = k mo SH = (0.8 - 0.9) So, wherein mH - heating apparatus mass mo - envelope mass k = (0.1 - 0.3) m °C/W
- coefficient of heat transfer of the material of the envelope, SH - area of a heating apparatus conductor, SO - area of one surface of the envelope, and the electrical current conductor is made of a plastic material having a resistivity of not more than 0.02 Ohm. mm2/m, say, copper.
The heating element of an electric heater, comprising an envelope with a heating apparatus disposed therein in the form of an electric insulated conductor of electric current, characterized in that the mass and area of the heating apparatus and the envelope have the ratio of:
mH = k mo SH = (0.8 - 0.9) So, wherein mH - heating apparatus mass mo - envelope mass k = (0.1 - 0.3) m °C/W
- coefficient of heat transfer of the material of the envelope, SH - area of a heating apparatus conductor, SO - area of one surface of the envelope, and the electrical current conductor is made of a plastic material having a resistivity of not more than 0.02 Ohm. mm2/m, say, copper.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2156085 CA2156085A1 (en) | 1993-12-14 | 1993-12-14 | Heating element of electric heater |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2156085 CA2156085A1 (en) | 1993-12-14 | 1993-12-14 | Heating element of electric heater |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2156085A1 true CA2156085A1 (en) | 1995-06-22 |
Family
ID=4156431
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2156085 Abandoned CA2156085A1 (en) | 1993-12-14 | 1993-12-14 | Heating element of electric heater |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2156085A1 (en) |
-
1993
- 1993-12-14 CA CA 2156085 patent/CA2156085A1/en not_active Abandoned
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Dead |