Abstract:
An electric steam iron is described. The iron includes a water reservoir and a soleplate. The soleplate includes a base, a heating element, a constant steam chamber in fluid communication with a plurality of constant steam chamber apertures passing through the base, and a steam shot chamber. The steam shot chamber includes a front cavity and a steam shot channel in thermal communication with the heating element and in fluid communication with the front cavity, the front cavity including at least one steam shot chamber aperture passing through the base, the steam shot channel defining a pair of flow paths substantially overlying the heating element, each flow path having a re-entrant shape. The iron further includes a constant steam chamber water delivery means for delivering water from the water reservoir into the constant steam chamber, and a steam shot chamber water delivery means for delivering water from the water reservoir into the steam shot chamber in the soleplate.

Description:
CLAIM OF PRIORITY 
       [0001]    The present patent application claims the priority benefit of the filing date of Australian Patent Application No. 2009902072, filed May 11, 2009, the entire content of which is incorporated herein by reference in its entirety. 
       FIELD OF THE INVENTION 
       [0002]    The present invention relates to a steam iron, and in particular a steam iron operable to deliver a shot of steam. 
       BACKGROUND OF THE INVENTION 
       [0003]    Irons for ironing clothes and other material are known. 
         [0004]    At a basic level such irons include a heating arrangement for heating a soleplate which can be slid over the material being ironed to remove wrinkles and creases. 
         [0005]    Steam irons include further componentry such that water is heated to steam and emitted from apertures in the soleplate while ironing. The steam emitted assists in the removal of wrinkles/creases from the material being ironed. 
         [0006]    Some steam irons also allow a user to operate the iron to deliver a shot of steam, passing water vapour at greater pressure through the material being ironed, further assisting in the ironing process. A shot of steam is a conventionally activated by depressing a button on the iron which causes a charge of water to be heated to steam and emitted from the apertures in the soleplate (this may be in addition to the constant steam being emitted). 
         [0007]    When using a steam shot function on a steam iron the user perception is often that a high-pressure shot of steam will be delivered at the front of the iron adjacent the tip of the soleplate. In many conventional irons, however, this is not the case. While steam is emitted from apertures in the soleplate at the front of the iron, the steam generation and delivery arrangement of the iron is such that the greatest steam pressure of a steam-shot is delivered through apertures in the rear of the iron soleplate, with the pressure decreasing towards the front of the iron. 
         [0008]    It would be desirable to provide a steam iron adapted to emit a steam-shot of relatively high pressure from the front of an iron. 
         [0009]    Reference to any prior art in the specification is not, and should not be taken as, an acknowledgment or any form of suggestion that this prior art forms part of the common general knowledge in Australia or any other jurisdiction or that this prior art could reasonably be expected to be ascertained, understood and regarded as relevant by a person skilled in the art. 
       SUMMARY OF THE INVENTION 
       [0010]    In one aspect the present invention provides an electric steam iron including: a water reservoir; a soleplate including: a base; a heating element; a constant steam chamber in fluid communication with a plurality of constant steam chamber apertures passing through the base; a steam shot chamber including a front cavity and a steam shot channel in thermal communication with the heating element and in fluid communication with the front cavity, the front cavity including at least one steam shot chamber aperture passing through the base, the steam shot channel defining at least one re-entrant flow path substantially overlying the heating element; the iron further including a constant steam chamber water delivery means for delivering water from the water reservoir into the constant steam chamber; and a steam shot chamber water delivery means for delivering water from the water reservoir into the steam shot chamber in the soleplate. 
         [0011]    The total length of the steam shot channel is preferably longer than the length of the heating element, and may be at least twice the length of the heating element. 
         [0012]    The soleplate may be of unitary construction. 
         [0013]    The iron may include a pair of flow paths, each flow path having a re-entrant shape. 
         [0014]    The pair of re-entrant flow paths may be symmetrical and meet at a confluence, and wherein the steam shot chamber water delivery means deposits water from the water reservoir into the confluence, the flow of the delivered water being split by a flow splitter so as to be divided between the flow paths. 
         [0015]    The constant steam chamber may include a central cavity in fluid communication with a pair of lateral channels in which the constant steam chamber apertures are located, the central cavity adapted to receive water from the constant steam chamber water delivery means and vent the received water as steam from the constant steam chamber apertures. 
         [0016]    The central cavity and lateral channels of the constant steam chamber and the steam shot channel and front cavity of the steam shot chamber may be defined by one or more walls extending normally from the soleplate. 
         [0017]    The iron may further include a soleplate cover adapted to seal the constant steam chamber and the steam shot chamber. 
         [0018]    The soleplate cover may include a first aperture through which the constant steam chamber water delivery means passes, and a second aperture through which through which the steam shot chamber water delivery means passes. 
         [0019]    The steam shot chamber may be in fluid isolation from the constant steam chamber. 
         [0020]    The steam shot chamber water delivery means may include a pump operable by a user to deliver water from the water reservoir to the steam shot chamber. 
         [0021]    The constant steam chamber water delivery means may include a constant flow-rate valve for delivering water from the water reservoir to the constant steam chamber at a predefined rate, the water delivered to the constant steam chamber vented as steam from the constant steam chamber apertures to provide a constant steam flow. 
         [0022]    In a second aspect the present invention provides an electric steam iron including: a water reservoir; a soleplate, the soleplate being of unitary construction and including: a base; a heating element; a constant steam chamber in fluid communication with a plurality of constant steam chamber apertures passing through the base; a steam shot chamber including a front cavity and a steam shot channel in thermal communication with the heating element and in fluid communication with the front cavity, the front cavity including at least one steam shot chamber aperture passing through the base, the steam shot channel defining at least one flow path substantially overlying the heating element, the at least one flow path having a re-entrant shape; the iron further including a constant steam chamber water delivery means for delivering water from the water reservoir into the constant steam chamber; and a steam shot chamber water delivery means for delivering water from the water reservoir into the steam shot chamber in the soleplate. 
         [0023]    The total length of the at least one flow path may be greater than the length of the heating element. 
         [0024]    The at least one flow path may include a pair of flow paths, each flow path in the pair of flow paths substantially overlying the heating element, and each flow path in the pair of flow paths having a re-entrant shape. 
         [0025]    In a third aspect the present invention provides an electric steam iron including: a water reservoir; a soleplate including: a base; a heating element; a constant steam chamber in fluid communication with a plurality of constant steam chamber apertures passing through the base; a steam shot chamber including a front cavity and a steam shot channel in thermal communication with the heating element and in fluid communication with the front cavity, the front cavity including at least one steam shot chamber aperture passing through the base, the steam shot channel defining at least one flow path substantially overlying the heating element, the at least one flow path having a re-entrant shape, the total length of the at least one flow path being greater than the length of the heating element; the iron further including a constant steam chamber water delivery means for delivering water from the water reservoir into the constant steam chamber; and a steam shot chamber water delivery means for delivering water from the water reservoir into the steam shot chamber in the soleplate. 
         [0026]    The at least one flow path may include a pair of flow paths, each flow path in the pair of flow paths substantially overlying the heating element, and each flow path in the pair of flow paths having a re-entrant shape. 
         [0027]    The soleplate may be of unitary construction. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0028]    An embodiment of the invention will be described with reference to the accompanying figures in which: 
           [0029]      FIG. 1A  shows a plan view of an iron soleplate in accordance with an embodiment of the invention; 
           [0030]      FIG. 1B  shows a partial diagrammatic view of the walls of the soleplate of  FIG. 1A , and the cavities and channels defined thereby. 
           [0031]      FIG. 1C  shows the iron soleplate of  FIG. 1A  with the element illustrated; 
           [0032]      FIG. 2  shows a perspective view of the soleplate of  FIG. 1A ; 
           [0033]      FIG. 3  shows a bottom view of the soleplate of  FIG. 1A ; 
           [0034]      FIG. 4  shows a partial perspective view of an iron fitted with the soleplate depicted in  FIG. 1A ; 
           [0035]      FIG. 5  shows a partial perspective view of the iron of  FIG. 4  with a cover fitted to the soleplate; 
           [0036]      FIG. 6  shows a sectional elevation view of the iron of  FIG. 4 . 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0037]      FIGS. 1 to 3  respectively provide a plan view, a perspective view, and a bottom view of a soleplate  100  in accordance with an embodiment of the invention. The soleplate  100  is for use with a steam iron which (as described in more detail below) can be operated to provide constant steam as well as a shot of steam. 
         [0038]    In the preferred embodiment the soleplate  100  is a single, integral Die casting. By providing a unitary soleplate  100  the complexities of soleplate assembly are minimised, facilitating a cost effective steam iron construction. The soleplate  100  will typically be cast from an aluminium alloy. 
         [0039]    The soleplate  100  includes a base portion  102  which has an underside surface  104  for ironing. As is known in the art the base portion  102  may be provided with a non-stick/low friction coating such as Teflon by DuPont, or a synthetic fluoropolymer such as polytetrafluoroethylene or polytetrafluoroethene (PTFE). The low friction coating allows the soleplate base to slide easily over the material being ironed. Alternatively, the base portion  102  may not be provided with a coating and, for example, the aluminium alloy (or other construction material) may simply be polished. 
         [0040]    On the upper side  106  of the base an outer wall  108 , a middle wall  110 , an intermediate wall  112 , an inner wall  113  (joined to the middle wall  110 ), and two bridging walls  114  (extending between the outer and middle walls  108  and  110  towards the front of the soleplate  100 ) are formed. Walls  108  to  114  each extend normally from the base portion  102 . While walls  108  to  114  are, for the purposes of illustration, described as separate features, the soleplate  100  of the preferred embodiment is (as noted above) of unitary construction and as such the outer, middle, intermediate, inner and bridging walls  108  to  114  are not in fact separate components but part of a single casting. 
         [0041]    As can be seen, the outer wall  108  forms a closed loop defining an inner chamber  116  in which the middle wall  110 , intermediate wall  112 , inner wall  113 , and bridging walls  114  are located. The middle wall  110 , inner wall  113  and the bridging walls  114  serve to separate the inner chamber  116  into a forward steam shot chamber  118  used in the generation of a steam shot and a rear constant steam chamber  120  used in the generation of constant steam. When assembled into an iron the forward and rear chambers  118  and  120  are in fluid isolation from each other and, as described below, the steam shot chamber  118  is used for providing a shot of steam and the constant steam chamber  120  for providing constant steam. 
         [0042]      FIG. 1B  shows a partial diagrammatic view of the walls ( 108 ,  110 ,  112 ,  113 , and  114 ) and the channels ( 123  and  136 ) and cavities ( 122  and  134 ) defined by the soleplate of  FIG. 1A . The dotted arrows in  FIG. 1B  indicate the direction of flow of steam. 
         [0043]    The steam shot chamber  118  is divided into a front cavity  122  and a steam shot channel  123 . As can be seen, the middle, intermediate and inner walls  110 ,  112  and  113  define the steam shot channel  123  to be effectively two re-entrant flow paths  126  joined at a confluence  128 , each flow path  126  feeding into the front cavity  122  at a channel opening  130 . The middle, intermediate and inner walls  110 ,  112  and  113  are each provided with offset protrusions  127  (not shown in  FIG. 1B ) which protrude into the re-entrant flow paths  126  and reduce the volume of the flowpaths  126 , thereby increasing pressure build-up in the flowpaths  126 . 
         [0044]    The front cavity is provided with a number of steam shot chamber apertures  132  (not shown in  FIG. 1B ) extending through the base portion  102  of the soleplate  100 . In the embodiment illustrated five steam shot chamber apertures  132  are depicted, however more or fewer could be provided as desired. 
         [0045]    The constant steam chamber  120  is divided into a central cavity  134  and a pair of lateral channels  136 . The central cavity  134  is in fluid communication with the lateral channels  136 , the lateral channels  136  extending between the outer wall  108  and the middle wall  110  and terminating at the relevant bridging wall  114 . The central cavity  134  is provided with a number of vanes  138  extending normally from the base portion  102  which, in use, assist in dividing water/steam between the two lateral channels  136  and act to draw water up the vanes  138  to aid the conversion of the water to steam. Each of the lateral channels  136  is provided with a number of constant steam chamber apertures  140  (not shown in  FIG. 1B ) extending through the base portion  102  of the soleplate  100 . 
         [0046]    The soleplate  100  also carries a heating element  142  which is cast into position in the soleplate  100  at the time of manufacture. The heating element  142  is a sheath type heating element in which a coiled resistance wire extends through a protective tubular sheath and is insulated therefrom by a compound such as granulated and compressed magnesium oxide. Alternative heating elements could be used if desired. The heating element  142  includes a pair of terminals  144  which (when the soleplate  100  is assembled into an iron) connect with a power source of the iron. 
         [0047]    In  FIG. 1C , the outline of the heating element  142  is shown, and as can be seen the heating element  142  is essentially U-shaped. Each arm of the heating element  142  extends below the re-entrant flow paths  126  of the steam shot channel  123 , with the U-bend of the heating element  142  proximate the confluence  128  of the steam shot channel  123 . As can be seen, the each of the re-entrant flow paths  126  doubles-back over the element  142 , allowing steam passing through the steam shot channel  123  to remain in close proximity to (and be heated by) the element  142  for a far larger distance than would be the case if non-re-entrant flow paths were used. This, in turn, allows the element  142  to heat the steam in the steam shot channel  123  for a longer period of time, thereby increasing the pressure of the steam shot eventually delivered. In one embodiment, the total length of the steam shot channel  123  (i.e. the combined length of the re-entrant flow paths  126 ) is longer than the length of the element  142 . 
         [0048]    The soleplate  100  is also provided with a plurality of mounting bores  148  by which an iron incorporating the soleplate  100  can be assembled. Some of the mounting bores  148  are provided in the walls  108  to  114  and some extend from the base portion  102  of the soleplate  100  as stand-alone bores. The bores  148  may be threaded for receiving screws or similar, or may be adapted to receive fabricated metal brackets which facilitate the mounting of moulded covers. 
         [0049]    The soleplate  100  may be provided with additional or alternative features depending on the particular arrangement of the iron with which the soleplate  100  is to be used. By way of example, the illustrated soleplate  100  includes a dial mount  150  which may be used (as shown in  FIG. 4 ) to mount a rotary mechanical thermostat by which a user operates the iron. The illustrated soleplate  100  also includes a disc mount  152  to which a bi-metallic disc may be secured to facilitate operation of an anti-drip valve assembly, preventing premature flow of water into the constant steam chamber  120  before the appropriate temperature is reached. 
         [0050]    Turning to  FIGS. 4 to 6 , partial depictions of an iron  400  including a soleplate  100  are provided. For the purpose of illustration the body  402  of the iron  400  has been depicted as being transparent, and not all components of the iron  400  are shown. 
         [0051]    Those components of the iron  400  illustrated include a handle  404  defined in the upper portion of the body  402  and a control dial  406  housed in the body  402  below the handle  404 . As is known the control dial  406  may be used by a user to set the iron temperature and/or mode of operation of the iron. At the front of the handle  404  a pair of triggers  408  and  410  are provided which operate (in this instance) a mechanical pump assembly  412 . Depressing one of the triggers (e.g. the left trigger  410 ) provides a spray mist to be generated via the nozzle  414 , and depressing the other trigger (e.g. right trigger  408 ) provides a shot of steam as discussed further below. 
         [0052]    In addition to the components of the iron  400  illustrated, the iron also includes a power source and cord (which exits the iron from cable guide  416 ) for providing power to the iron. 
         [0053]    As shown in  FIG. 5 , when iron  400  is assembled the top of the soleplate  100  (i.e. the tops of walls  108  to  114 ) is provided with a cover  502  which serves to seal the soleplate  100  (and in particular the inner chamber  116 ) from a water reservoir  506  that is defined within the body  402  of the iron. The cover is provided with a plurality of securing apertures  504  which align with a selection of the bores  148  to allow the cover  502  (and iron body/componentry) to be secured in place—e.g. with screws. The cover  502  is also provided with a number of component apertures through which necessary components (described below) pass without allowing water from the water reservoir to leak into the inner chamber  116  or, conversely, water/steam in the inner chamber  116  to escape through the cover  502 . 
         [0054]    In one mode of operation the iron  400  is configured to provide a constant outlet of steam through the constant steam chamber apertures  140 . This is achieved by a drip valve  405  (or similar) which passes through the cover  502  and allows a regulated flow of water from the water reservoir  506  to the constant steam chamber  120 . The specific regulated flow rate for the drip valve will depend on the size and construction of the iron and the desired volume of constant steam to be emitted. In one embodiment the flow rate may, for example, be approximately 30 millilitres/minute. In an alternative embodiment the flow rate may be approximately 35 millilitres/minute. In a further alternative embodiment the flow rate may be approximately 40 millilitres/minute. Still further alternative flow rates, either within or outside the range of 30-40 millilitres/minute, may, of course, be implemented. 
         [0055]    The drip valve deposits water into the central cavity  134  of the constant steam chamber  120  where it is heated by heat from the heating element  142  (either directly or transferred through the soleplate  100 ) to generate steam. As pressure in the central cavity  134  builds up the steam is directed into the lateral channels  136  (via vanes  138 ) where it exits the iron  400  via the constant steam chamber apertures  140 . In addition to providing constant steam, the iron  400  may also be operated to generate a shot of steam through the steam shot chamber apertures  132 . To generate the shot of steam an amount of water from the water reservoir  506  is delivered to the steam shot channel  123 , and in particular to the confluence  128  of the steam shot channel  123 . In the illustrated embodiment this is achieved by the user depressing the steam-shot trigger (e.g.  408 ) which operates the pump  412  to pump water from the water reservoir and deposit it in the steam shot channel  123  (via a conduit  418  which passes through the soleplate cover  502 ). The specific volume of water to be deposited in the steam channel  123  will depend on a number of factors, including the desired volume of steam to be emitted in a single steam shot. In one embodiment the volume for a single shot of steam may be approximately 0.5 millilitres. In an alternative embodiment the volume for a single shot of steam may be approximately 0.6 millilitres. Further alternative volumes, either within or outside the range of 0.5 to 0.6 millilitres may, of course, be used. 
         [0056]    As noted above, the confluence  128  of the steam shot channel  123  (i.e. the point at which water from the water reservoir  506  is delivered) and the re-entrant flow paths  126  substantially overlay the heating element  142 . When water is delivered to the confluence  128  where it is heated to steam, the flow of the steam being divided between the re-entrant flow paths  126  (the bend in the inner wall  113  acting as a flow-splitter). The re-entrant shape of the flow paths  126  provides for a relatively long flow path, and as the entire length is in close proximity to the heating element  142  the water is quickly boiled to steam, and the pressure of the steam increased. The steam eventually exits the re-entrant flow paths  126  into the front cavity  122 , and from there is “shot” (by virtue of the pressure) out the steam shot chamber apertures  132 . 
         [0057]    It will be understood that the invention disclosed and defined in this specification extends to all alternative combinations of two or more of the individual features mentioned or evident from the text or drawings. All of these different combinations constitute various alternative aspects of the invention.