US2683320A - Steam iron - Google Patents

Description

E. o. MORTON STEAM IRO File 5, 1948 [6/7, I ,Go

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.9. I T TO Patented July 13, 1954 STEAM IRON Eldred 0. Morton, Mansfield, Ohio, assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application November 5, 1948, Serial No. 58,520

2 Claims. 1

This invention relates to pressing irons of the type providing steam for moistening material being pressed and has for its object an improved iron of this type.

A further object of this invention is to provicle a steam iron of the type generally known as the flash type, with improved steaming qualities.

Another object of this invention is to eliminate spitting of water particles from the soleplate during the pressing operation.

In domestic steam irons of the fi'ash type, the space available for steam generation is Very limited; therefore, if the water does not wet the steam-generating chamber surface, it forms globules or droplets that float around over the hot surface. This phenomenon retards complete evaporation with the result that droplets of water are carried by the steam to the soleplate of the iron, causing spotting of delicate fabrics.

To overcome this problem, I coat the steamgenerating chamber surface with a hydrophilic material which provides a wettable surface and causes the incoming liquid to spread over the surface, thus providing a greater area of contact between the liquid and the steam generating surface. Such materials come within the class known as wetting as capillary agents. There are several hydrophilic materials which can be used, but I prefer to use a sodium silicate solution. Under these conditions a high rate of heat transfer is obtained, the water is quickly converted to steam and the possibility of Water particles being entrained with the steam and carried to the soleplate is eliminated or minimized. Although sodium silicate is preferable for commercial application at low cost, the steam-generating chamber may be coated with any of a number of hydrophilic materials to condition the steaming surfaces. The following materials are given by way of example: sodium carbonate, calcium carbonate, calcium acid carbonate, magnesium carbonate, magnesium acid carbonate, sodium bicarbonate, sodium chloride and sodium sulphate. Any one or more of these materials may be used to condition the steaming surfaces. These materials may be carried in solution in water or other liquids or may merely be carried in suspension in any appropriate liquid vehicle to facilitate application to the steamgenerating surface. The concentrations of the above materials in the liquid vehicle is not considered to be important since a mixture of high concentration will require a smaller amount than a mixture of low concentration to provide the required coverage.

In the accompanying drawing used for illustration purposes:

Fig. 1 is a side elevation, with parts in section; and

Fig. 2 is a top plan view of the soleplate.

As shown in the above drawing, a steam iron generally indicated I0, is electrically heated and comprises a metallic soleplate H, a sheet metal cover or shell member [2 and a plastic or wood handle I3 which are fastened together in any suitable manner. The cover houses a waterstorage chamber or reservoir I4. The soleplate may be of conventional shape as illustrated in Fig. 2, and is provided with a heating element it which is generally U-shaped as shown by the dotted lines in Fig. 2. The heating element is preferably cast into the soleplate, and may be of the sheathed type containing an outer tube or sheath l6 housing a coiled resistance element ll centrally disposed and spaced from the outer sheath by a highly compacted refractory insulating material l8.

A thermostat i9 is centrally positioned in the soleplate H in a well 20 which is defined by a Wall 2! preferably formed integrally with the soleplate.

The wall 2| together with an outer wall 22 and a V-shaped rib 23 define a steam-generating chamber 24 and passages 25. A plurality of outlet ports 26 lie in a V-shaped channel 27 adjacent to the V-shaped rib 23 and are shielded from'direct communication with passages 25 by the rib.

A cover plate 28 is secured to the soleplate H by any suitable means and serves to enclose the V steam chamber 2 the passages 25 and the outlet ports 26, thus preventing escape of steam except through the outlet ports in the soleplate. This cover plate has a transverse channel 29 which serves as a. connecting passage between passages 25 and the V-shaped channel 2?. The steam is thus allowed to flow from the steam chamber 2t through passages 25 to channel 29, through the channel into the V-shaped channel 21, and from the V-shapecl channel through the outlet ports 26 to the bottom of the soleplate.

The water reservoir Hi has a needle valve 30 by means of which it communicates with the steam chamber 24. This valve registers with an opening in a plate 3! which overlies an opening in the cover plate 28 and is fastened thereto. The valve and plate 3! are maintained in leakproof contact by an annular gasket 32. In order to reduce the conductivity from the cover plate to the water reservoir Hi, this plate is preferably constructed of light gauge material.

3 An adjustment knob 33 serves to adjust the valve 30 in order to vary the entry of water into the steam chamber and thus controls the rate of steam generation.

The confining surfaces of the steam chamber 24 and the passages 25 are coated with a hydrophilic material such as, for example, a solution of sodium silicate, in their pre-assembly stage. The hydrophilic material is indicated by stippling 24A. To insure that these confining surfaces are fully coated when the parts are assembled, it is expedient to coat the upper and edge surfaces of the soleplate H. The bottom and edge surfaces of the cover plate 28 and the bottom surface of the plate 33 may also be coated, if desired. The surface of the well 20 need not be coated, since it is sealed against steam or water access. Also, the soleplate has a heel portion 34, the upper surface of which need not be coated. Although the specific gravity of the silicate solution is not critical and may vary over a fairly wide range, a water solution having a specific gravity of 1.35 is preferred, since it has been found satisfactory for application directly to the evaporating surfaces. The ratio of NazO to SiO2 in the sodium silicate may vary over a wide range such as from 1:2 to 123.75, respectively, although I prefer to use sodium silicate having a ratio of 1:322. The coated parts are then air dried and assembled into the iron.

Upon completion of the iron assembly a quantity of dilute sodium silicate solution, containing between per cent and per cent sodium silicate in water is passed into the reservoir 14 and through the valve 32 while the iron is energized. This additional treatment coats the valve stem and the orifice of valve 36 with a thin layer of sodium silicate which will cause the Water to flow more readily from the water reservoir i i to the steam-generating chamber 24. To insure against clogging of the valve a quantity of Water is then passed into the reservoir l4 and through the valve 3% in similar fashion. The iron is now fully treated and will operate satisfactorily without the usual spitting of partially vaporized water through the soleplate. Steam irons which have not been subjected to the above treatment will spit water for a period of time until their steanngenercting surfaces become coated with lime depos left by the evaporating water. This period of 0 1c is commonly known as the breaking in period; however, irons treated in the manner described need no breaking in period since in chest they have been broken in by this method of manufacture.

To operate the iron, the reservoir I4 is filled with water and the iron is energized by connecting to an electrical outlet in the usual way provided for electrical appliances of this type. To operate as a steam iron, the knob 33 is rotated to any steam volume position desired, thus opening the valve 39 to an extent allowing the required flow of water from the reservoir to the steam-generating chamber 24. This flow is in the nature of a dripping action, and the water drops will be caused to spread by the wetting surface and instantly flash into steam upon contact with the hot steam chamber surface. The steam will then flow along the channels and passages provided until it escapes through the outlet ports 26 to the bottom of the soleplate. There its elfect is to dampen the article being ressed, thus eliminating the need for pro-dampening the article as is customary when dry ironing. When it is desired to use the iron as a dry iron in the conventional manner, the knob 33 is rotated to the closed position, thus closing the valve 32 and stopping the flow of water from the reservoir It to the steam chamber 24.

While I have shown my invention in but one form, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various changes and modifications without departing from the spirit thereof.

What I claim is:

l. A steam iron comprising a soleplate, a vapor-generating chamber of the flash type, means including a valve for admitting water in drop-let form to said chamber and means for transmitting vapor from the vapor-generating chamber to the lower surface of said soleplate, said chamberhaving side wall surfaces and a bottom wall surface, said side and bottom Wall surfaces being coated with a hydrophilic material to cause water to spread and thereby to facilitate vaporization.

2. The structure recited in claim 1 in which said hydrophilic material is sodium silicate.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,323,131 Goodfellow Nov. 25, 1919 1,571,962 Overton Feb. 9, 1926 1,530,545 Swartz et a1 May 31, 1927 1,964,592 Nerad June 26, 1934 2,104,528 Richardson Jan. 4, 1938 2,299,789 Black Oct. 2'7, 1942 2,317,706 Woodman Apr. 2'7, 1943 2,336,807 Schwartz Dec. 14, 1943 2,387,281 Morton Oct. 23, 1945

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