Abstract:
A self-cleaning steam iron has a self-cleaning function. The self-cleaning function is activated by an integrated steam control means which also controls the steam level in the ironing mode. The control means resets a steam iron to the ironing mode after each self-cleaning but does not alter the steam level set in the ironing mode unless a self-cleaning is performed subsequent to the steam level setting.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to a steam irons and, more particularly, to electric steam irons having means to clean the internal steam paths of the iron.  
         BACKGROUND OF THE INVENTION  
         [0002]    Many domestic and professional irons are equipped with steam generating and delivery means to supply steam for ironing. Steam generating irons are generally preferred to non-steam generating irons because it is generally accepted that ironing can be done better, easier and at a lower temperature with steam. This characteristic is particularly important for ironing the more delicate and expensive clothes, clothing materials or fabrics.  
           [0003]    Steam in a steam iron is generally produced by delivering water to a heated sole plate to cause vaporization of the water. The vaporization process causes a sudden expansion in volume which will cause steam to leave the iron through the internal steam vents.  
           [0004]    Tap water is usually used for steam generation in steam irons because of its low cost and convenience. However, it is a known problem that particles, impurities and other depositable or precipitable substances in tap water, especially hard water, will cause blockage of the internal steam vents or paths of the steam irons after prolonged used. This is largely due to the deposit, precipitation or accumulation of the impurities, dirt or the perceptible substances along the steam paths results in narrowing and ultimately blocking of the steam paths.  
           [0005]    Steam irons with built-in self-cleaning means which allow users to clean the steam and water paths of the steam irons by steam generated by the iron are generally known. Self-cleaning is generally done by supplying a large amount of water from the reservoir to the steam boiler inside the iron so that a large volume of steam is suddenly generated within a short time. The sudden generation of steam causes highly pressurised steam to force its ways through the steam paths and vents, thereby removing the loosely deposited impurities and precipitation before they become too difficult to remove.  
           [0006]    In most self-cleaning irons, a single integrated steam controller is usually provided to control the generation and supply of steam so that the generated steam can be used either for ironing or for cleaning, but not both. Such a design generally allows the use of a single water source and the same steam paths for both cleaning and ironing while ensuring that the iron only operates in one of the alternative modes.  
           [0007]    A known disadvantage of such self-cleaning steam irons is that, when an unwary user uses an iron for ironing after a previous user left the steam iron in the self-cleaning mode, excessive steam may be generated. This sudden supply of steam generated in the self-cleaning mode may accompany with it a spray of dirt or other undesirable substances onto the clothes, which can be expensive and delicate, to be ironed. Hence, it will be desirable to provide a self-cleaning iron which substantially alleviates the afore-said short-comings of conventional self-cleaning irons.  
         OBJECT OF THE INVENTION  
         [0008]    In view of the afore-said short-comings of conventional self-cleaning irons, it will be appreciated that there is a long awaited need and demand for self-cleaning irons which substantially alleviates the afore-said shortcomings. Hence, it will be an object of the present invention to provide a self-cleaning iron which is provided with a single steam control means which are configurable between ironing and cleaning mode and which automatically restores the iron to the ironing mode after each use to alleviate the known problems of convention self-cleaning steam irons.  
           [0009]    At the same time, it is highly preferred that such a steam control means is provided with means to maintain the steam level setting in the ironing mode unless a self-cleaning is performed subsequent to the setting.  
           [0010]    It is therefore an object of the present invention to provide self-cleaning steam irons with improved steam control means which restore a steam iron to the ironing mode after each self-cleaning. Preferably the steam control means do not alter the steam level set in the ironing mode unless a self-cleaning is performed subsequent to the steam level setting. It is also an object that such a preferred and useful steam control means should be simple and inexpensive for the benefit of the general public. As a minimum, it is an object of the present invention to provide the public with a useful choice of self-cleaning steam irons having the steam control means of the present invention.  
         SUMMARY OF THE INVENTION  
         [0011]    According to a first aspect of the present invention, there is provided a steam iron including a main housing, a reservoir, a steam generating chamber, a valve and a valve controller, said reservoir being communicable with said steam generating chamber through said valve, said valve includes a first and a second alternative valve aperture defining regions for varying the extent of communication between said reservoir and said steam generating chamber, wherein the size of the aperture defined by said first aperture defining region is generally smaller than that defined by said second aperture defining region, and said controller includes means to urge said valve to return towards said first region.  
           [0012]    Preferably, said valve includes an elongated shaft having a longitudinally extending groove. Preferably, the cross-sectional area of at least a part of said groove varies along its length.  
           [0013]    In one specific example, said valve includes an elongated shaft and said valve controller includes a rotary member which is connected to said shaft via a transmission link, said controller includes means to restrain said transmission link in a fixed location on said rotary member when said valve is operating in said first aperture defining region, said controller further includes means to urge said shaft to move towards said first region when said valve is operating in said second aperture defining region. Preferably, said elongated groove includes a portion which tapers towards the end of said shaft not connected to said controller.  
           [0014]    In the same example, said controller includes a rotary member which is connected to said shaft via a transmission link, said rotary member includes a crank track for receiving a portion of said transmission link, said crank track is substantially radially disposed on said rotary member. Preferably, said crank track includes a first and a second region corresponding to the valve operating in said first and second aperture defining regions, wherein when said valve is operating in said first valve defining region, said received portion of said transmission link is substantially maintained at a fixed location with respect to said rotary member, when said valve is operating in said second aperture defining region, said received portion is moved along said crank track under an urging force.  
           [0015]    Preferably, said rotary member includes means to move said transmission link along said crank track when said valve operates in said second aperture defining region.  
           [0016]    Preferably, said valve controller includes a rotary member, a pusher, a spring bias means, a crank track, a transmission link connecting said rotary member to said shaft, wherein a portion of said crank track is received and slidable along said crank track, said portion of said crank track is located at a fixed position relative to said rotary member when said rotary member moves between a first and a second angular positions, said portion is moved along said crank track under an urging force when said rotary member rotates beyond said angular range.  
           [0017]    In another specific example, wherein said valve controller includes a lever handle member having a first, a second and a third arm, wherein said first arm is for use by an user, said second arm is for driving said piston member in said first region and said third arm is for driving said piston into said second region under spring bias.  
           [0018]    According to a second aspect of the invention, there is provided a steam iron including a steam controller, said controller including a valve and a valve controller, said valve includes at least a first and a second operative regions corresponding to variable aperture sizes for steam generation, said controller includes means to control said valve to operate either in said first region or said second region, said controller also includes biasing means to return said valve to said first operating region when said valve is set to operate in said second region.  
           [0019]    Preferably, said first operating region includes aperture of variable sizes for ironing and said second operating region includes apertures for generating steam for self-cleaning of said iron. Preferably, said controller includes lever means to control said valve to operate in either said first region or said second region, wherein, said lever means will be subject to a spring urge to return the said first region when said lever means transitions from said first operating region to said second operating region. Preferably, said controller includes a cam member to drive said lever means to said second operating region and against spring bias. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]    Preferred embodiments of the present invention will now be explained, by way of example, and with reference to the accompanying drawings, in which:  
         [0021]    [0021]FIG. 1 is a side view partly in section showing a steam iron having a first preferred embodiment of the steam control device of the present invention;  
         [0022]    [0022]FIG. 2 shows the embodiment of FIG. 1 in a disassembled condition;  
         [0023]    [0023]FIG. 3A is an enlarged view of the steam control device of FIG. 1 in the “ironing” mode;  
         [0024]    [0024]FIG. 3B is an enlarged view of the steam control device of FIG. 1 in the self-cleaning mode;  
         [0025]    [0025]FIG. 3C is an enlarged view of the steam control device of FIG. 1 transitioning between the ironing and self-cleaning mode; and  
         [0026]    [0026]FIG. 3D shows an orthogonal view of the relationship between the piston and the outlet nozzle of FIG. 3B.  
         [0027]    [0027]FIGS. 4A, 4B &amp;  4 C are enlarged views of the second embodiment of the steam control device with the piston member in positions corresponding respectively to that of FIGS. 3A, 3B and  3 C. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0028]    Referring to FIGS.  1  to  3 D, there is shown a preferred embodiment of an improved electric steam iron ( 1 ) which includes a first preferred embodiment of an improved steam control means of the present invention. The steam iron includes a handle ( 2 ), a reservoir housing ( 3 ), a soleplate ( 4 ) with an electric heater and a steam chamber which is formed and enclosed between the soleplate ( 4 ), a main housing and a reservoir ( 3 ). The main housing and the reservoir housing ( 3 ) are preferably made of a heat resistant plastic material such as polypropylene for storing water and for steam generation. The steam control means ( 5 ) generally includes a valve and a valve controller.  
         [0029]    The valve generally controls the volume flow rate of water which can flow from the reservoir ( 3 ) to the steam chamber ( 34 ) according to the various steam requirements. The volume flow rate can be controlled, for example, by varying the aperture size of the valve which separates the reservoir ( 3 ) and the steam generating chamber. Of course, other volume flow rate controlling means can also be employed in place of a conventional valve without loss of generality.  
         [0030]    The valve employed in the present preferred embodiment includes an elongated shaft member ( 11 ) on which a first and a second valve operating regions corresponding respectively to the ironing and the self-cleaning modes are formed. In general, the elongated shaft member ( 11 ) is formed with a profile of varying cross-sectional area along its length. This varying cross-sectional profile of the valve together with the aperture separating the reservoir ( 3 ) and the steam generating chamber together forms an aperture of variable sizes, depending on the instantaneous position of the shaft ( 11 ) with respect to that aperture.  
         [0031]    In the first region of the shaft member corresponding to the ironing mode, a longitudinal groove ( 12 ) is formed on the piston member. The groove generally tapers towards the free end and ends a short distance above the free end of the shaft or piston member. A groove of this tapering design permits gradual variation of the aperture size to vary the steam level in a controlled manner. The free (or distal) end of the shaft member corresponds to the second valve operating region and includes a thin blade-shaped member ( 13 ) to allow maximum flow of water from the reservoir ( 3 ) to the steam chamber in the self-cleaning mode.  
         [0032]    The near end of the elongated shaft or piston member ( 11 ) is connected to a valve controller. The other end (the distal end) of the shaft is free and can be moved by the valve controller towards and away from an outlet nozzle ( 31 ), which is an aperture separating the reservoir and the steam generating chamber.  
         [0033]    To form a valve having a variable aperture size, the elongated shaft member ( 11 ) is received within a through cylindrical well ( 32 ) which is formed through the reservoir in a direction substantially normal to the plane of the reservoir housing ( 3 ) and that of the soleplate ( 4 ). At the base of the cylindrical well, an slotted outlet nozzle ( 31 ) is provided. This outlet nozzle permits water in the reservoir to flow under gravity from the reservoir into the steam chamber unless blocked. With this arrangement, the reservoir is communicable with the steam chamber through the outlet nozzle and the extent of communication between the reservoir and the steam chamber is controllable by the instantaneous aperture formed between the nozzle ( 31 ) and the shaft member ( 11 ).  
         [0034]    The shaft or piston member ( 11 ) generally includes a first and a second valve operating regions corresponding respectively to the ironing and the self-cleaning modes. In the ironing mode, as shown in FIG. 3A, a gentle and controlled supply of steam is generally required. It is desirable that the supply of ironing steam is gradually adjustable to cater for specific ironing requirements. For example, cotton requires a stronger steam supply while silk or other synthetic materials generally require less. To cater for this, a valve having a variable aperture size is realized by forming a generally longitudinally extending groove with a varying cross-sectional area along the length of the shaft member. In this embodiment, the varying cross-sectional area is implemented by having a tapered groove formed along the shaft length and the portion of the groove which encounters the outlet nozzle will define the instantaneous aperture size of the valve.  
         [0035]    When the grooved region of the shaft member moves longitudinally towards and away from the outlet nozzle, the communication between the reservoir and the steam chamber will increase and decrease respectively due to the tapered shape of the groove which provides different cross-sectional clearance between the nozzle outlet ( 31 ) and the shaft ( 11 ). When the non-grooved region of the main piston member is aligned with the nozzle, there is no communication and the outlet nozzle, and therefore the steam supply, is blocked. Of course, the manner of the change of the valve aperture size, which is determined by the instantaneous clearance between the well and the shaft, relative to the longitudinal movement of the piston member will be reversed if the orientation of the groove tapering is reversed. Thus, the steam iron is in the ironing mode when the grooved portion of the shaft is aligned with the outlet nozzle ( 31 ), since only a relatively small and controlled volume of water will be allowed into the steam chamber. When the shaft member ( 11 ) is lifted further away from the nozzle so that the thin blade portion is aligned with the nozzle or when the shaft member is lifted entirely above the nozzle as shown in FIGS. 3B and 3D, water will flow freely into the steam chamber through the outlet nozzle, thereby providing a steady supply of steam for and corresponding to the self-cleaning mode.  
         [0036]    In transitioning from the ironing mode as shown in FIG. 3A and the self-cleaning mode as shown in FIG. 3B, the shaft-outlet pain may pass through a no-steam region in which the outlet is blocked by the piston.  
         [0037]    The valve controller includes a rotary drive member ( 21 ) and a crank member ( 22 ) connecting the rotary member ( 21 ) and the shaft member ( 11 ). The crank member ( 22 ) includes an elongated member for motion transmission between the rotary drive member ( 21 ) and the shaft member ( 11 ). Transversal members ( 23 ,  24 ) are provided at both ends of the crank member ( 22 ) for making hinged connections respectively with the rotary driver member ( 21 ) and the piston member ( 11 ).  
         [0038]    The rotary drive member includes a pusher ( 25 ), spring-biasing means ( 26 ) and a crank track ( 27 ). The crank track ( 27 ) is provided to receive the protruding ends of the transversal member of the crank member ( 22 ) and is adapted to allow the transversal member to move from one extreme position to another. The track is generally radially disposed so that the crank end will move in a generally radial manner with respect to the rotary member when it is forced to move along the crank track ( 27 ).  
         [0039]    The rotary member includes a spring-bias means which initially maintains the crank end in a position nearest the axis of the rotary member ( 21 ). Because of the restraint by spring bias means, the crank end is substantially stationary relatively to the rotary member initially and the rotary movement of the rotary member will translate into a translational movement of the shaft member due to the crank member ( 22 ) connection. This direct translation of movement will end when the pusher ( 25 ) encounters the crank member at which point the crank end will be pushed to move along the crank track under spring bias. In this configuration, the crank track includes a first and a second region. In the first region, the crank end ( 23 ) is substantially restrained by spring biasing means and in the second region, the crank end ( 23 ) is urged by the spring biasing means to return to the first region.  
         [0040]    For reasons to be explained below, the crank track is generally disposed so that it is tilted generally upwards when the pusher ( 25 ) engages the longitudinal crank member. It will be noted from the description below that the steam iron will be in the ironing mode when the transversal member is restrained in the first region and the iron will be in the self-cleaning mode when the transversal member is pushed away from the region of the crank nearest the axis of the rotary member.  
         [0041]    The rotary member ( 21 ) is rotatable between a first and a second position corresponding to the top-dead end and bottom-dead end of the shaft or valve member ( 11 ) because of the crank ( 22 ) connection. When the piston is at the top-dead end, the thin-blade will be aligned with the outlet nozzle ( 31 ). Of course, the piston member can be lifted wholly above the nozzle, this corresponds to the self-cleaning mode. When the piston moves from the top-dead end to the bottom-dead end, it enters the ironing mode and goes through the various steam level setting by aligning the appropriate groove ( 12 ) section with the outlet nozzle.  
         [0042]    The arrangement of the rotary member is such that, by moving between the said first and second positions, the piston member and thus the steam iron will go through the ironing mode with a change of steam level and the self-cleaning mode. It will be explained below how the valve control device is operated to drive the piston member ( 11 ) so that the iron is automatically reset from the self-cleaning mode to the ironing mode after each self-cleaning.  
         [0043]    As explained above, when the iron is in the ironing mode, the level of ironing steam can be varied by changing the size of the aperture which is formed by the meeting of grooved region of the piston member ( 11 ) and the outlet nozzle ( 31 ). This is set by rotating the rotary member clockwisely or anti-clockwisely so that the appropriate grooved region of the piston member aligns with the nozzle aperture ( 31 ), thereby setting the desired steam level. The steam level thus set in the ironing mode will remain unchanged after each setting by friction means. When self-cleaning is desired, the piston member ( 11 ) is further lifted so that the thin blade portion is aligned with or the piston member is even lifted above the nozzle.  
         [0044]    Referring to FIGS. 3A to  3 C, it will be seen that when the rotary member ( 21 ) is rotated anti-clockwisely, the transversal member of the crank will follow the rotary member and the vertical component of the movement thus produced will lift the piston member. This continues until the pusher ( 25 ) engages the longitudinal member of the crank. At this point, continued anti-clockwise rotation of the rotary member will drive the transversal member ( 23 ) along the crank track ( 27 ) into the second region and against biasing spring. This tracking along the crank track ( 27 ) lifts the transversal member and therefore the piston member since the second portion of the crank track ( 27 ) is disposed above the first portion and is tilted upwards when at this position.  
         [0045]    As the transversal member is under spring bias when it is in the second region, it will return to the first region when the withholding force has been released. Hence, by designing the steam control device so that the piston member ( 11 ) begins to enter into the self-cleaning mode when the transversal member engages the pusher and remains in the same mode when the transversal member tracks along the slot means into the second region, the piston will be reset to the ironing mode position after the withholding force has been released. In this arrangement, it will be noted that the iron will be reset to the ironing mode after each self-cleaning but the steam level set in the ironing mode will not be altered unless there is a subsequent self-cleaning.  
         [0046]    Referring to FIGS. 4A to  4 C, there is shown a second embodiment ( 41 ) of the steam control means of the present invention. The steam control means in this embodiment is substantially the same as that of the first embodiment but with the rotary member replaced by a lever arm means. The lever means has a first ( 42 ), a second ( 43 ) and a third ( 44 ) arm and is pivotably mounted on a shaft which is substantially transversal to the axis of the piston member. The first arm ( 42 ) is provided for a user to set the steam level or to activate self-cleaning by pivotably varying the position of the lever. The second arm is located between the first arm and the shaft and is for connecting to the piston member ( 11 ) so that pivotal movement of the first arm will be translated into vertical displacement of the piston member, thereby allowing a variation of the steam level and self-cleaning. The third arm is located between the second arm and the shaft and is disposed in a manner such that it will engage a spring means when the piston member has been elevated to a position which corresponds to self-cleaning mode. Similar to the first embodiment, the steam level setting of the iron will be maintained by friction and the spring means will reset the iron from the self-cleaning mode to the ironing mode after each self-cleaning and on release of the withholding force.  
         [0047]    While two preferred embodiments of the valve controller have been disclosed above, it would be obvious, without loss of generality, to persons skilled in the art that other variations or equivalents of the steam control device can be devised to achieve the same purpose, namely, utilisation of an improved steam control device so that a steam iron operable in the ironing and self-cleaning mode can be restored or reset to the ironing mode after each self-cleaning. Also, the steam level set in the ironing mode would preferably not be changed unless the iron is set into the self-cleaning subsequent to the steam level setting.