Electric heating – Heating devices – With heater-unit housing – casing – or support means
Reexamination Certificate
2002-05-11
2003-11-18
Bennett, Henry (Department: 3742)
Electric heating
Heating devices
With heater-unit housing, casing, or support means
C219S545000, C219S212000, C219S217000, C219S202000, C219S386000, C165S061000, C165S064000, C165S104280
Reexamination Certificate
active
06649886
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to electric heating fabrics, and more particularly to an electric heated cloth and method for the generation and maintenance of a required temperature in a certain local zone. The invention also relates to a conducting resistive thread used in the heated cloth.
BACKGROUND OF THE INVENTION
Present-day demands to control temperatures generate a high interest in flexible electric heating devices that may be used to ensure environment adaptation to a temperature parameter. Cloth heaters are a type of flexible electric heater representing a flexible means of heating various surfaces and media that are easily adapted to the application site. Among the devices that require use of cloth electric heaters are automotive heated seats, heated steering wheels, automotive engine oil crankcases, cement hardening heaters, clothes with heating elements, thermal blankets, etc.
In some applications, such as automotive seat heaters, it is desirable that permanent operating heater temperature of approximately 37° C. be maintained, with provisions to raise it to about 150° C. within a short period of time during fabrication of seats in order to ensure melting of an adhesive material that ensures gluing of the car seat material to a foam.
Introduction of modern composite materials that can withstand reasonably high temperatures made it possible to produce devices that are not susceptible to limitations on the maximum heating temperature within a permissible range. Use, in the cloth, of “shell-nucleus” type conducting resistive threads produced with the help of known processes does not make it possible to expand the temperature range as required, due to reasons that will be described below.
For example, from WO, 95/17800, HO5B 3/36, publ. Jun. 29, 1995, an electric heating weaved thread cloth is known that has 0.3-3.5 kOhm/m linear electric resistance conducting resistive threads both in the weft and the warp. The conducting resistive thread used in the known cloth has a “shell-nucleus” structure, in which the “nucleus” consists of polycaproamide fiber, and the “shell” that serves as the resistive material is a composite that includes a tetrafluoroethylene co-polymer with vinylidene fluoride and industrial carbon. The conducting resistive thread is produced by applying a coat of resistive material on polycaproamide fiber.
The disadvantages of this conducting resistive thread are: low linear electric resistance, which limits its use to fabrication of woven heating elements that are suitable for work at voltages not exceeding 36 V; use of polycaproamide fiber of a certain configuration, only, as a “shell” for its production; and higher resistive material consumption.
Besides, the heating temperature of the woven heating element, produced using this thread as a basis, cannot exceed the polycaproamide fiber melting point (100-110° C.), otherwise, the heating element will be ruined. Two conducting bus bars arranged in the same direction as non-conducting threads are located in the cloth at a considerable distance from one another, thus making wire connection inconvenient. U.S. Pat. No. 4,983,814, 219/545, HO5B 3/34, publ. Jan. 8, 1991 contains a description of electric heating cloth with 1-100 kOhm/m linear electric resistance conducting threads in the weft.
The conducting resistive thread for this fiber also has a “shell-nucleus” structure, in which the “nucleus” consists of a Nylon®, polyester or polyolefin type (all having low melting points within 100-120° C. temperature range) synthetic fiber or high-melting polyfluoroethylene and polyamide type, and the “shell” that serves as the resistive material, is a composite that contains a polyester type polyurethane resin and a carbon filler at a mass ratio of 1:0.3 and 1:1, respectively.
The carbon filler used is industrial carbon (produced from oven or channel acetylene, and their mixtures) or graphite (natural, with a dense crystalline, flaky or amorphous structure, and artificial) at a mass ratio of 1:1.67 and 1:4 (column 8, paragraph 2 in the description) or 1:0.5 and 1:0.6 (in examples 1 and 2), respectively.
The conductive resistive thread is produced by applying from one to three coats of the resistive material to the synthetic thread described above at a mass ratio of 1.7:1 and 2.8:1, respectively.
The disadvantages of this conductive thread are: requirement to apply two or three coats of the resistive material on the resistive thread “nucleus” and heavy consumption of the resistive material even with single-coat “shell”, which increases the thread production cost. Besides, this conductive thread has two conductive bus bars that are arranged in the same direction as non-conducting threads and located in the cloth at a considerable distance from one another, thus making wire connection inconvenient.
In view of the above, some requirements may be set forth that the conducting thread should meet, namely: improvement in heating properties of flexible heaters; uniform heating of the cloth surface for higher user comfort; bigger operating temperature range; conveniences during the installation of the heating element and lower production cost. The market needs a better heating material that may be used in various applications and be reliable and efficient.
SUMMARY OF THE INVENTION
The invention is based on the tasks of developing an electric heating cloth that is heated uniformly over the entire surface of the cloth; developing an electric heating cloth which has a wide operating temperature range; and developing an electric heating cloth which has multiple heating sections over the entire surface of the cloth which minimizes the necessity of having multiple electric outlets, making connections to a power source more convenient and reducing the cost of fabricating electric heaters.
The technical result achieved therein lies in enhancement of service properties of the electric heating cloth, its reliability and efficiency due to uniform heating of the cloth surface area; opportunities to heat different fiber sections to different temperatures; and convenience during fabrication of flexible electric heaters.
According to this invention, the electric heating cloth consists of a set of primary non-conducting threads and at least two conducting bus bars arranged along the warp. Between the pair of conducting bus bars there is a second set of primary non-conducting threads and heating conductive resistive threads. At least two distributing bus bars are connected to the conducting bus bars in order to supply electric power. Each conducting bus bar and each distributing bus bar contains at least one low-resistance thread that serves as an electric conductor. Primary heating and low-resistance threads make up the main set of elements required to form an electric heating cloth that has suitable structure and suitable temperature range characteristics.
This technical result is achieved because the electric heating cloth per fabrication alternative
1
, which is a cloth produced by interweaving the threads and consisting of cotton or synthetic primary non-conducting threads arranged in the first direction, and 2.7-1800 Ohm/cm linear electric resistance conducting resistive threads arranged in the second direction, perpendicular to the first one, each of them consisting of synthetic or glass fiber with a shell from polymer resistive material that contains a carbon filler consisting of industrial carbon and graphite, has at least three conducting bus bars arranged in the first direction which coincides with the direction of the primary non-conducting threads for distribution of electric energy between conducting resistive threads, and at least two distributing bus bars arranged in the second direction which coincides with the direction of conducting resistive threads and separated from the latter by non-conducting cotton or synthetic fiber threads that are arranged in the second direction as well and create a dielectric barrier between the distributing bus bars and conducting resistive threads, in which there are circuit br
Bennett Henry
Fuqua Shawntina
Rhodes Alex
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