Abstract:
To prevent water particles or mist carried by steam exiting from the steam vents of a steam iron, the steam generated in its steam chamber follows tortuous paths from both a vaporization section and a blast path to the steam vents. A baffle having a concave front face spans across the rear of the vaporization section and the open rear ends of the blast path face the concave baffle face. The lid of the steam chamber is sealed by pressure to the baffle and to a pair of ribs that define the sides of the blast path. The outer rib is higher than the inner rib so that, if the seal between the lid fails, the failure will likely occur between the inner rib and the lid so that any water escaping from the blast path will likely enter the vaporization chamber and not exit through a steam vent.

Description:
FIELD OF THE INVENTION 
     This invention relates generally to a steam iron and a method of manufacturing the same. This invention is primarily concerned with household steam irons but aspects of the invention may be useful in other applications. 
     BACKGROUND OF THE INVENTION 
     Steam irons commonly have a soleplate comprising a metal casting having insert-molded heating elements extending through the casting, typically along a generally U-shaped path parallel to the bottom of the soleplate. A portion of the top the soleplate is covered by a sheet metal lid to form a steam chamber. The steam chamber is typically divided into a vaporization section, a blast path, and a steam vent section. The steam vent section may be divided into two or more subsections which may or may not be in open communication with one another. The vaporization section is located within the area between the legs of the U-shaped path of the heating element. Steam is produced during the normal course of operation by water dripped into the vaporization section onto a heated, upwardly-facing surface of the soleplate. The water is heated as it flows along the upper surface of the soleplate and converted into steam. The steam thus produced exits from the vaporization section into the steam vent sections through tortuous steam channels formed by surfaces included in the design of the soleplate. Plural steam outlet vents in the steam vent section permit steam to exit from the bottom of the soleplate onto the fabric or other material being pressed by the steam iron. 
     The steam blast path is located directly above, or almost directly above, an elongate portion of the heating element. Steam created along the blast path usually enters the steam vent sections through the same tortuous channels, or a portion of such channels, along which steam formed in the vaporization section passes. 
     A pair of ribs, namely an outer rib and an inner rib define the sides of a blast path. The ribs are ordinarily covered and sealed by the steam chamber lid. If the seal between the outer rib of the blast path and the chamber lid fail, water or water vapor from the blast path could escape the blast path and enter directly into the steam vent section. As result, water could exit the steam vent and cause undesirable “trailing” of streaks of water on the material being pressed. Trailing can also occur if water which has not been entirely vaporized into steam, either in the vaporization section or along the blast path, is permitted to enter the steam vent sections through the steam channels which are intended to direct only steam into the steam vent sections. 
     SUMMARY OF THE INVENTION 
     This invention provides an improved steam chamber for a steam iron and a method of manufacturing the improved steam chamber. 
     A primary object of this invention is to provide manufacturing methods and steam iron constructions for reducing trailing caused by the passage of water from the steam vents of a steam iron. 
     A more specific object of this invention is to prevent water particles or mist carried by steam exiting from the outlet of either the vaporization section or the blast path from entering into the steam vent section. In addition to providing a tortuous path through which the steam must flow in order to enter the steam vent section, in accordance with this invention a baffle is located at the rear of the steam chamber. The baffle has a concave front face spanning across substantially the entire rearward end of the vaporization section. The baffle functions in a manner analogous to a concave mirror, with regard to the blast path, tending to direct vapor toward the center and the front of the vaporization section. The baffle also functions, with respect to the vaporization section and the blast path, to keep water particles not completely vaporized from entering into the steam vent sections. Water particles striking the baffle will tend to accumulate and puddle in front of the baffle. Advantageously, the blast path has rearwardly facing openings that tend to direct vapor exiting from the blast path toward the baffle. Accordingly, whether the source of any water particles that have not been completely vaporized in the vaporization section or the blast path, the water will be confined in front of the baffle and be restrained from entering into the steam vent sections. 
     Another more specific object of this invention is to provide an improved seal between the steam chamber lid and the ribs that define the sides of the blast path. In accordance with this aspect of the invention, the inner and outer ribs forming the sides of the blast path are at different heights, the inner rib being slightly lower than the outer rib, and, during manufacture, the steam chamber lid is pressed onto the inner and outer ribs with sufficient force that the lid is sealed to the tops of both the inner and the outer ribs. Rivets are provided to help maintain the seals between the lids and the inner and outer ribs. If a failure in the sealing of the lid to the ribs should occur, the failure is most likely to occur between the lid and the inner rib because the inner rib has a height lower than the outer rib. Upon the occurrence of such a failure, water may extend over the inner wall into the vaporization section but will not extend over the outer wall into the steam vent section. Water entering the vaporization section will most probably be completely vaporized into steam or else be confined to an area in front of the rear baffle, as described above, so that the failure of the seal between the inner rib and the lid will not lead to a trailing problem. 
     In another aspect of this invention, an object is to improve the response of a canister type thermal cut off device (TCO) to prevent an excessive thermal runaway of an iron. It is conventional to locate a TCO between the soleplate and the base cover of a steam iron. This invention follows such conventional practice and, in addition, provides a base cover having a dome in which the TCO is located. Accordingly, the TCO has a substantial volume of air surrounding it within which heat can be retained so that a thermal build-up is sensed more rapidly than if the TCO were closely confined between the soleplate and the base cover. 
     Other objects and advantages will become apparent from the following description and the drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a steam iron made in accordance with this invention. 
     FIG. 2 is an exploded isometric view of the iron of FIG.  1 . 
     FIG. 3 is a bottom plan view of the iron of FIG.  1 . 
     FIG. 4 is an exploded perspective view of the soleplate, including a heating element illustrated by phantom lines, the steam chamber lid, and a thermostat used to control the temperature of the heating element. 
     FIG. 5 is a top plan view of the soleplate. 
     FIG. 6 is a cross-sectional view taken along line  6 — 6  of FIG.  5  and diagrammatically showing a press plate. 
     FIG. 7 is an enlarged cross-sectional view taken from the circle  7  of FIG. 6 of a blast path located in the steam chamber. 
     FIG. 8 is an isometric view of the soleplate and the steam chamber lid and showing a thermostat and electrical connections thereon. 
     FIG. 9 is a simplified, side elevational view, with parts in cross section, of the steam iron of this invention shown resting upright on its rear cover. 
    
    
     DETAILED DESCRIPTION 
     With reference to FIGS. 1 and 2, the present invention is illustrated in connection with a household steam iron, generally designated  10 , having a soleplate  12  with a steam chamber  14 , covered by a base cover  16  which supports a handle  18 . Handle  18  has a lower portion  20  which confines a water reservoir  21  and an upper portion  22  which receives an electronic control module  24  and which is covered by a top cover  26 . The handle upper portion  22  and the top cover  26  constitute a handgrip. In addition, the iron  10  includes a rear cover  28 , a temperature control knob  30  for setting a thermostat  32  mounted on the soleplate  12 , and a drip valve assembly including a drip valve stem  34  for dripping controlled quantities of water into the steam chamber  14  through a drip valve seal  35 . As well known, the water dripped into the steam chamber  14  is heated by a U-shaped electrical heating element  15  (FIGS. 4 and 6) in the soleplate  12 , vaporizes and forms steam which exits from the soleplate  12  through plural steam vents  13  (FIGS.  3  and  5 ). Terminals  15 A of the heating element  15  and the electronic controls are connected to house current by means of a power cord connected to the rear cover  28 . The particular iron  10  shown in the drawings also has a pair of manually-operable pistons  36  and  38 , respectively used to spray water forwardly of the iron through a nozzle  40  and to create a burst of steam by pumping water by way of a thermoplastic tube connection  42  into the steam chamber  14 . The water reservoir  21  has a forwardly projecting front face  44  and a water conduit  46  extending through the front face  44  into the hollow interior of the reservoir  21 . A fill port assembly, generally designated  48 , is used to enable one to pour water into the water reservoir  21  and also to cover the water conduit  46  during normal use of the iron to prevent contaminants from entering into the reservoir  21 . 
     Referring now to FIGS. 3 through 6, the steam chamber  14  is formed between the soleplate  12 , which may be cast from aluminum, and a steam chamber lid  50 , which may comprise an aluminum plate. As is typical of iron soleplates, the soleplate  12  has a generally triangular shape, having a rearwardly convexly curved rear edge  54  and convexly curved side edges  56  that come to a rounded point  58  at its front end. The steam chamber  14  has an upstanding outer wall  60  of a triangular peripheral shape similar to the outer periphery of the soleplate  12 . Outer wall  60  has an upwardly-open channel  62  along its entire length. The steam chamber lid  50  comprises a flat plate portion  64  bounded by a peripherally-extending skirt  66  that is shaped and sized to be inserted into the outer wall channel  62 . 
     For purposes of holding the steam chamber lid  50  on the soleplate  12 , cast as part of the soleplate  12  are plural upstanding rivet bosses  67  having reduced diameter heads that project through aligned apertures  68  in the soleplate lid  50 . A thermostat boss  70  is also cast with the soleplate  12  and a hole  72  for receiving the upper end of the thermostat boss  70  is formed in the steam chamber lid  50 . Also cast with the soleplate  12  are three large rivet bosses  74  having D-shaped heads which are adapted to hold connecting twist tabs  75  (FIGS. 2 and 8) used to affix the base cover  16  to the soleplate  12 . The forwardmost large rivet boss  74  is located in the steam chamber  14  and a hole  76  therefor is provided in the lid  50 . 
     In addition to the several bosses mentioned above, the soleplate  12  includes a blast path  80  defined by an upstanding outer rib  82  and an upstanding inner rib  84  that extends over a substantial portion of the length of the heating element  15 . A surge of water can be pumped onto a portion of the soleplate  12  located between the outer rib  82  and the inner rib  84  and essentially directly over the U-shaped forward end of the heating element  15 , the water being forced through a seal  86  (FIG. 2) located in a hole  88  in the lid  50  by operation of the piston  38 . 
     A baffle  90  located at the rearward end of the steam chamber  14  has a concave front face spanning across substantially the entire rearward end of the steam chamber  14 . 
     The blast path ribs  82  and  84 , the baffle  90 , and the raised portions of the soleplate  12  that accommodate the heating element effectively divide the steam chamber  14  into three sections, namely, the blast path  80 , a central vaporization section  92 , and an outer steam vent section  94 . All of the steam vents  13  are located in the steam vent section. In the soleplate design illustrated in the drawings, there are four sets of steam vents  13 , a set of rear vents in back of the rear baffle  90 , two sets of side vents which are located outside the margins of the heating element  15  and the outer rib  82 , and a set of front vents located between the nose of the outer rib  82  and the nose of the steam chamber  14 . 
     For ordinary steam operation, water is introduced through the drip valve seal  35  into the front end of the vaporization section  92 . As the water is vaporized to produce steam, the steam travels toward the back of the vaporization section  92  and follows a tortuous paths indicated by arrows in FIG. 5 around the baffle  90  to the rear steam vents  13  or around the rearward ends of the outer ribs  82  to the side and front vents  13 . As explained above, the baffle  90  tends to direct vapor toward the center and the front of the vaporization section  92  so that water particles striking the baffle  90  will tend to accumulate and puddle in front of the baffle  90  and not reach the steam vent section  94 . 
     When a blast of steam is produced by operation of the piston  38 , the steam is formed along the length of the blast path  80  and exits the rearward end of the blast path  80  in a stream directed at the concave front face of the baffle  90 . Accordingly, as with vapor created in the vaporization section  92 , water particles that have not completely vaporized into steam will strike the baffle  90  and tend to accumulate in front of the baffle  90  and not enter into the steam vent section  94 . 
     With reference to FIGS. 6 and 7, the outer blast path rib  82  and the baffle  90  are preferably at the same height relative to the bottom surface of the soleplate  12 . In contrast, as shown best in FIG. 7, the inner blast path rib  84  is slightly lower than the outer blast path rib  82 . For example, if the lid  50  is formed from a sheet of aluminum which is 0.025 inch thick, the inner blast path rib  84  may be on the order of 0.020 to 0.040 inch lower than the outer blast path rib  82 . 
     During manufacture, the soleplate  12  is die cast to the desired shape and the lid  50 , formed as illustrated in FIG. 4, assembled onto the soleplate  12  by first applying a sealant, such as RTV, into the soleplate&#39;s outer wall channel  62 . The lid  50  is then assembled onto the soleplate  12  with the lower, outer, edge of the lid skirt  66  inserted into the channel  62 . Thereafter, the lid  50  is pressed into sealing engagement with the top surfaces of the outer and inner blast path rib  82  and  84  and the baffle  90 . As diagrammatically shown in FIG. 6, a press plate  100  having a flat pressure-applying lower surface provided with apertures to accommodate the various rivets or bosses can be used to create the sealing engagement of the lid  50  with the ribs  82  and  84  and the baffle  90 . Preferably, sufficient pressure is applied to the lid  50  by the press plate  100  that impressions of the outer blast path rib  82  and the baffle  90  are visible in the top surface of the lid  50  as shown in FIG.  8 . The rivets formed on the rivet bosses  67  are thereafter peened into engagement with the upper surface of the lid  50  to maintain the sealing engagement of the lid  50  to the soleplate  12  and the connecting tabs  75  connected to the bosses  74  by peening their rivet heads. Sealant is then applied over the rivet heads on top of the lid  50 . 
     With reference to FIGS. 2,  8 , and  9 , the electrical components for controlling the iron  10  include a TCO fuse  96  mounted between the soleplate  12  and the base cover  16 . As well known in the art, the TCO  96  would open circuit the heating element  15  in the event of a thermal runaway condition. In accordance with this invention, the base cover  16  is formed to include a dome  98  overlying the TCO  96  that accumulates and retains, in the area around the TCO  96 , heat created by the operation of the iron  10 . Accordingly, the TCO  96  is exposed to heat conditions which, even when the iron is resting in an upright position as shown in FIG. 9, are highly representative of the heating of the soleplate  12 . The provision of the dome  98  enables the use of a TCO  96  which will not open the heating element circuit unless a genuine thermal runaway condition is encountered. 
     The shape and size of the dome  98  should be determined by trial and error, however, the distance from the outer diameter of the TCO  96  to the inside crown of the dome  98  is preferrably in the range of 3 to 4 mm. With reference to iron  10  resting on its soleplate  12 , rib  102  shown in FIG. 9 extends below the lowermost canister portion of TCO  96 . Therefore, when the iron  10  is in its upright position as shown in FIG. 9, rib  102  assists dome  98  in accumulating and retaining heated air in the area around TCO  96 , allowing TCO  96  to better sense the heat created by the operation of the iron  10 . 
     In FIG. 2, it will be observed that the base cover  16  has a channel  100  extending from the rearward end of the iron  10  and leading to the dome  98 . The channel  100  accommodates electrical connections to the TCO  96  and also provides a path for directing heated air to the dome  98 . The channelling of heated air to the dome  98  increases the effectiveness of the dome  98  in causing the TCO  96  to respond quickly to thermal runaway conditions. 
     Although the presently preferred embodiment of this invention has been described, it will be understood that within the purview of the invention various changes may be made within the scope of the following claims.