US 1703005 A
Description (OCR text may contain errors)
Feb. 19, 1929. 1,703,005
. F. w. HEWITT ELECTRIC HEATING PAD AND FABRIC Filed Jan- 5, 1928 2 sheets-sheet 1 Feb. 19, 1929.
F. W. HEWITT ELECTRIC HEATING PAD AND FABRIC Filed Jan. 5 I928 2 Sheets-Sheet 2 5&6: 7
M w W Patented Feb. 19, .1929.
UNITED STATES rnanx w. rmwrr'r, or ARLINGTON,- irassacmrsn'r'rs.
ELECTRIC HEATING PAD AND FABRIC.
Application filed January 5, 1928. Serial No. 244,744.
This invention relates to flexible electric heating pads and the like wherein a resistance wire is disposed on and is supported by a flexible fabric in such a manner as to provide a flexible construction and to distribute heat approximately uniformly over the surfaces of the pad.
Heating pads of the type above set forth have usually contained a relatively high resistance wire as the heating element, which wire may be in the form of a spiral or coil; and the wire is usually contained in a heat insulating sheath and has only a relatively .few folds.
It is an object of this invention to provide a flexible electric heating pad consisting of a flexible woven fabric having warp strands of textile fibres and having the woof cons1sting of a continuous strand of fibrous material wound with a, spirally-formed contmu ous electric conductor of low resistance, which conductor is without a heat-insulating sheath and is exposed for free heat radiation 1 and convection from its surface. A further object of the invention is the pro vision of an electric heating pad having its opposite covers, or faces, formed of mate rials having different heat-conducting properties, whereby different degrees of heat may be obtained merely by placing one or the other side of the pad in contact with the body to receive heat.
A further object is generally to im rove the construction of electric heating pa s.
A yet further object is an improved method .of manufacturing electric heating pads.
Fig. 1 is a plan detail illustrating the manner of making the heating fabric embodying the invention.
Fig. 2 is an enlarged side elevation of Fig. 1.
Fig. 3 is afragmentary plan view of a woven heating fabric drawn approximately to full scale.
Fig. 4 is a detail of the heating element and illustrating more particularly the construction thereof.
Fig. 5 is an enlarged plan detail of'a heating fabric adapted for use with a similar 50 heating fabric having a. heating elementof a different resistance and wherein the heating element bears an identifying characteristic.
Fig. 6 is a plan view of a heating pad conss structed in a rdance with the invention and with a portion of the external cover removed to expose a heating fabric.
Fig. 7 is a section along line 77 of Fig. 6 and illustrating more particularly the internal construction of the heating ad.
Fig. 8 is, a section similar to Flg. 7 but illustrating a modified construction wherein the superimposed heating fabrics are formed from a continuous section of fabric.
As here shown the Woven heating fabric embodying the invention comprises the textile strands 10 which form the warp of the fabric. Said warp strands may consist of cotton or other fibres; and the strands may be relatively widely spaced apart, say about one-eighth of an inch, or as illustrated in Fig. 2. The warp at the edges of the fabric may have a double strand, as at 10*, whereb to provide increased strength at the side e es. Thewoof of the fabric comprises a heating element 11, and the warp and the woof may be Woven in any suitable manner, as to form a simple basket-weave, as shown. The heating element, or woof, is continuous and is woven with the warp in such a manner that the warp strands hold the adjacent folds or strands of the heating element in spaced relation; and the spacing between the folds of the heating element may be about equal to the spacing between the warp strands.
The heating element may include a flexible core 13 of textile fibres, as cotton for instance. A continuous electrically conducting wire 14 is wound in a spiral mannerover said core, to secure flexibility, and the convolutions of said wire are spaced from each other, whereby to provide free access of air to the surface of the convolutions. Preferably the heating element, comprising the wire and core, has a diameter about equal to that of the warp strands, whereby a uniform woven fabric may result. Said electric conductor is preferably of fine enamel-insulated copper Wire, whereby to provide for a large extent of wire and, therefore, large heatdissipating surface although any other wire having similar characteristics may be used. I
In the process of manufacture, the fabric is woven in long len hs suflicient to form a large number of smal er heatin fabrics. The heating element comprising t .e woof, is interwoven with tlie'warp strands until a sufficient length of heating element is woven to produce a heating fabric having the desired characteristics, as power consumption, etc.,
whereupon the heating element is passed along the outside of the warp strands for a suitable distance and then again interwoven with the warp strands, and this process is re peated as desired. The long fabric is thus formed with woven sections a connected and separated by unwoven sections 5 occupied aplurality of heating fabrics having the sam power consumption. Preferably, howei er, and particularly for heating pads having two heating elements or fabrics having different rates of power consumption, the procedure is different; and the preferred method is illustrated in Fig. 2. .A long length of fabric woven as above set forth has superimposed upon it a suitable fabric supporting sheet 16. A second long length of heating fabric issuperimposed upon the supporting fabric in such a manner that the woven portion a and unwoven portions 6 of the two heating fabrics are in vertical register. Spaced lines of stitching 17 are then passed through all of the sheets, in the unwoven portions of the heating fabrics; and the stitching serves to unite allthe superimposed fabrics together and also to bind the warp strands of the heating fabrics in place. 7 The united and superimposed fabrics may be out between the lines of stitching, as at w-ca, and each section, when the heating elementsare properly connected electrically, is in readiness to be inserted in the covers of a heating pad. If the heating pad is designed, however, to have two heating fabrics of the same power consumption, I may cut the long fabric into short sections each containing two woven sections separated by unwoven warp strands,
and fold the short section to superpose the woven sections as illustrated in Fig. 7 and the warp strands may be continuous throughout both upper and lower heating fabrics. If
I the heating pad is designed to have two heating fabrics having different rates of power consumption, I'prefer to weave two sets of fabrics, similar to that illustrated in Fig. 1, but with different heating elements, and I may form one heating element with an identif ing characteristic, as by weavin a colored t need 12 thereon Fig. 5, where readily to identify thegdiiferent heating fa rics.
* The heating elements of the superposed heating fabricsmay' beconnected to an electric circuit in any well known manner, and
by suitable means as the switch 20, whereby to obtainapluralit pf heats. One or more thermostat! 18, o more or less usual construction, may be disposed between-er upon said superposed fabricate be heated by. both fabrics, and included in 'the circuit through the heating elements in a more or less common manner to protect said heating elements against an undue elevation of temperature- The heating fabrics are adapted tobe enclosed within an enclosing casing formed, preferably, of two sheets of material, or covers, having dissimilar heat-conducting characteristics and united together by suitable means as the lines ofstitching 21. One sheet or cover, as the sheet 23, may have the property of being a relatively good heat conductor and the other sheet, as the sheet 24;, may have the property of conducting heat at a slower rate than that of said first sheet. With this arrangement, when the cover 23 is in contact with the bodyto be heated, the effect of a high heat may be obtained, and when the cover 24 is in contact with the body, the effect of a lower heat maybe obtained, and without altering the electric connections of the heating elements.
The connection of heating elements with the power circuit, under control of the switch 20, is adapted to be such that three dilferent heats may be obtained. Since thecovers 23 and 24 provide'one additional heat with each circuit ar angement of the heating elements, as ordinarily but one side of the heating pad is used at one time the above described construction of the covers provides a pad having a total of six heats.
The cover sheets 23., and 24 are preferably made of relatively soft and flexible materials.
The cover sheet 23,fo1i instance, may be made of suitably pre ared cotton which permits heat to be con ucted through it at a relatively rapid rate. The cover sheet 24 may be made of eiderdown, for instance, through which heat may be conducted at a slower rate.
It is to be noted that the weave of the heating fabrics and the relation of the fabrics and the cover-sheets is such that air ockets 26 are formed, in which air pockets t e heating elements are disposed; and heat may be radiated from the heating conductor directly to the cover-sheets of the pad; and the air has free access to the surface of the heating elements and may circulate freely over the heated surface thereof and give up its heat to the cover-sheets, whereby to heat said cover-sheets uniformlyover practically their entire extent.
1. An electric heating pad including a fiexi ble loosely woven heating fabric having a warp com. osed of strands of spaced textile fibres, and a homogeneous woof of continuous fibrous materialwo'und with an exposed I fine co per wire with the convolutions thereof space apart. 2. Anelectr'ic heating pad including, a flexible loosely woven heating fabric having a warp composed of strands of spaced textile fibres, and a homo eneous-woof of continuous fibrous materia wound with an exposed fine copper wire with the convolutions thereof spaced apart, and a fabric enclosure for said heating fabric.
3. An electric heating pad having two layers of loosely Woven heating fabric made as described in claim 1, stitched to an intervening supporting fabric.
4. An electric heating pad having two layers of loosely woven heating fabric made as described in claim 1, stitched to an intervening supporting fabric, and a fabric enclosure for said fabrics.
5. An electric heating pad having opposed heat-conducting faces, each composed of materials having different heat-conducting properties, and an electric heating element disposed between said opposed heat-conducting faces. 7
6. An electric heating pad having an electric heating element including means to provide a plurality of heats therefrom, and an enclosing casing for said'heating elementhaving opposed heat-conducting covers composed of materials having different heat-conducting properties.
7. 'An electric heating pad having a flexible loosely woven heating fabric made as described in claim 1 and enclosed in a flexible casing having two opposed cover-sheets coning supporting fabric and all enclosed in a flexible casing having two opposed coversheets constructed of materials having different heat-conducting properties.
9. Asa new article of manufacture, a flexible woven heating fabric comprising a plurality of spaced woven sections consisting of insulating warp strands and electrically conducting woof strands, the woven sections being connected b unwoven sections having warp strands n y and being free from said I attached fabrics between the lines of attachment.
11. The method of manufacturing electric heating pads which consists in forming two separate lengths of flexibleheating .fabric, each length having s accd woven sections including a heat-ing e ement, and intervening unwoven sections, superposing said lengths of fabric with their woven and unwoven sections in, vertical register and with a length of a flexible textile supporting fabric interposed between the heating fabrics, attaching all fabrics together along two spaced transverse lines located theunwoven sections of the heating fabrics, and cutting said attached fabrics betwe'en'the lines of attach- 'ment.
In testimony whereof, I have signed my name to this specification.
FRANK W. HEWITT.