Electric heating – Heating devices – With heating unit structure
Patent
1995-08-14
1998-06-02
Walberg, Teresa J.
Electric heating
Heating devices
With heating unit structure
219553, H05B 344, H05B 310
Patent
active
057603774
DESCRIPTION:
BRIEF SUMMARY
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 45.degree. C. and intended for the therapeutic 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 accomodates an electric heating apparatus made from conducting material, generally insulated wire (U.S. Pat. No. 4,614,189, nat. cl. 128-380, 1984; GB Patent No. 1038891, ICI 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.mm.sup.2 /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 arises, due to elasticity inherent in said materials, difficulties in forming the heating wire and what is more, highly complicated is uniform distribution of wire in the body of the envelope of the heating element. Irregularity of the wire distributed results in local overheating, 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. To avoid 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.
SUMMARY OF THE INVENTION
It is the principal object of the present invention to select such parameters of a heating wire and the envelope of a heating element such that this heating element has a higher coefficient of heat transfer per unit mass than available heating elements and is more adaptable to streamlined production as well.
The task set is solved owing to the fact that the heating element having an envelope and a heating wire accomodated therein according to the invention, the mass and area of the envelope and heating wire are selected from the ratio:
m.sub.H denotes mass of a heating wire,
m.sub.o denotes mass of an envelope,
S.sub.H denotes area of a conductor of the heating wire,
S.sub.o denotes area of one surface of the envelope and
.lambda. denotes the coefficient of heat transfer of the material of the envelope
An electric current conductor is made from flexible material having specific resistance not exceeding 0.02 ohm.mm.sup.2 /m, say, copper.
If the area of a heating wire 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 thicknes
REFERENCES:
patent: 3524965 (1970-08-01), Arron
patent: 3904850 (1975-09-01), Johnson
patent: 4063069 (1977-12-01), Peeri
patent: 4455481 (1984-06-01), Van Hoof et al.
patent: 4628188 (1986-12-01), Andreason
patent: 4665308 (1987-05-01), Courvoisier et al.
patent: 4954676 (1990-09-01), Rankin
patent: 4983814 (1991-01-01), Ohgushi et al.
Peskov Nikolai Evgenievich
Piletsky Gennady Konstantinovich
Stroev Evgeny Alexeevich
Zelenjuk Jury Iosifovich
Paik Sam
Walberg Teresa J.
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