Patent Document

BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an ironing appliance comprising a pump that includes a pumping chamber equipped with an inlet and an outlet, the pumping chamber including a movable wall displaceable under the action of a piezoelectric actuator for displacing the membrane in order to aspirate fluid through the inlet and then discharge it through the outlet. 
     2. Description of Related Art 
     Japanese patent application #62142597 discloses a clothing iron comprising a piezoelectric pump that supplies a vaporization chamber with water from a receptacle. In this document, the piezoelectric pump is vertically positioned and includes a pumping chamber comprising an inlet and an outlet positioned vertically one above the other, the outlet being located below the inlet. 
     However, such a piezoelectric pump has the disadvantage of not enabling rapid and easy expulsion of air bubbles introduced in the pumping chamber, for example during no-load operation of the pump in the absence of water in the receptacle. In particular, with such a configuration of the piezoelectric pump, the air bubbles tend to get stuck in the top portion of the pumping chamber and cannot be expelled. 
     A piezoelectric pump has the disadvantage of having a movable wall with only a very slight clearance such that pump performance is greatly diminished when bubbles are present in the pumping chamber. 
     SUMMARY OF THE INVENTION 
     Hence an object of the present invention is to remedy these disadvantages by proposing an ironing appliance in which the piezoelectric pump is configured such that the expulsion of any air bubbles present in the pumping chamber is enabled and good pump performance is obtained, even after no-load operation. 
     To this end, the object of the invention is an ironing appliance comprising a pump that includes a pumping chamber equipped with an inlet and an outlet, the pumping chamber including a movable wall that comprises an outer surface in contact with a piezoelectric actuator provided to move the movable wall while changing the volume of the pumping chamber by means of the piezoelectric actuator, characterized in that the pump is placed in the ironing appliance in such a way that the outlet of the pumping chamber is located at a higher level than the inlet in a normal position for operating the appliance. 
     “Normal position for operating the appliance” is understood to mean a position of the appliance corresponding to a customary and preferred use of said appliance. In the case of a clothing iron with a heating sole, the normal operating position thus corresponds to the position in which the clothing iron is resting on its sole. 
     According to another characteristic of the invention, the pump comprises a support that includes the inlet and outlet of the pumping chamber, and the movable wall of the pumping chamber is aligned vertically. 
     According to still another characteristic of the invention, the inlet and the outlet pierce the support, the latter element comprising a face interior to the pumping chamber that includes a channel extending between the inlet and the outlet. 
     According to still another characteristic of the invention, the pumping chamber has a circular shape, wherein the inlet emerges near the center of said pumping chamber and the outlet is located near the periphery of said pumping chamber. 
     According to another characteristic of the invention, the pump comprises a film sandwiched between the support and a base plate, the latter comprising a delivery line and a discharge line that communicate with the inlet and the outlet of the pumping chamber, respectively, the film comprising valves opposite the inlet and the outlet. 
     According to another characteristic of the invention, the film is made of silicone and the valves are formed by making an arc-shaped cut in the film. 
     According to another characteristic of the invention, the cut is in the shape of an arc whose endpoints form an angle less than 180°. 
     According to another characteristic of the invention, the appliance is a clothing iron comprising a receptacle and a vaporization chamber supplied with water from the receptacle by means of the pump. 
     According to another characteristic of the invention, the pump is connected to a water reservoir placed downstream from the pump. 
     According to still another characteristic of the invention, a drip valve is interposed between the water reservoir and the vaporization chamber. 
     According to another characteristic of the invention, the pump is positioned vertically in the back of the iron, outside of the receptacle. 
     According to another characteristic of the invention, the pump is positioned level with the bottom of the receptacle. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The objects, aspects, and advantages of the present invention will emerge more clearly from the following description of an illustrative embodiment of the invention provided as a nonlimiting example, with reference to the appended drawings in which: 
         FIG. 1  is a perspective view of a clothing iron according to a particular embodiment of the invention; 
         FIG. 2  is a partially exploded perspective view of the clothing iron of  FIG. 1 ; 
         FIG. 3  is a side view of the clothing iron of  FIG. 1  with its top portion removed in order to reveal the elements placed in the interior of the receptacle; 
         FIG. 4  is a perspective view of the piezoelectric pump of the iron of  FIG. 1 ; 
         FIG. 5  is a cutaway view of the pump of  FIG. 4 ; 
         FIG. 6  is an exploded perspective view of the pump of  FIG. 4 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Only the elements needed for understanding the invention have been shown. To make the drawings easier to read, the same elements have the same reference numbers from figure to figure. 
       FIG. 1  shows a clothing iron comprising a pressing sole  1  surmounted by a body equipped with a handle  2 , the body enclosing a water receptacle  3  and a piezoelectric pump  100  supplied by the receptacle  3 , the operation of which is controlled by means of a trigger (not visible in the figures) provided under the handle  2 . 
     According to  FIG. 2  illustrating the iron in exploded view, the sole  1  of the iron thermically contacts a heating element  10  that integrates, in a manner known per se, a vaporization chamber  11  for generating steam, wherein the vaporization chamber is closed by a lid  12  and connected to a steam dispensing circuit that includes steam outlet holes bored in the sole  1 . 
     In order to restrict the heat from being conducted to the iron handle  2 , the heating element  10  is surmounted by a heat screen  4  that comprises a center portion  40  defining the bottom of the receptacle  3  and a peripheral portion constituting a protective skirt  41  that extends under the bottom of the receptacle  3  and matches the contour of the sole  1  in such a way that it laterally borders the heating element  10 . 
     The center portion  40  of the heat screen  4  is bordered by a groove  42  in which a wall (not visible in the figures) defining the top portion of the receptacle  3  engages, said wall being borne by a top casing element  5  attached onto the heat screen  4 . An example of such a two-part receptacle assembly is described in more detail in French patent application #2 770 856 filed by the applicant. 
     The top casing element  5  comprises the handle  2  for gripping the iron and supports a cord guiding mechanism  6  for aligning the electric cord of the iron. The casing element  5  further comprises a hatch  7  for accessing a fill hole for the receptacle  3 , a knob  8  for adjusting a thermostat associated with the heating element  10 , and buttons  51 ,  52  for actuating manual pumps for discharging a spray of water from a nozzle  53  placed on the front face of the iron or for the instantaneous discharge of a volume of water into the vaporization chamber  11  for generating extra steam, respectively. 
     According to  FIGS. 3 and 4 , the heat screen  4  comprises a back portion that supports the piezoelectric pump  100 , wherein the latter element is placed on the outside of the receptacle  3 , roughly level with the bottom of the receptacle, and comprises a delivery line  131  and a discharge line  132  connected to a first coupling sleeve  91  and a second coupling sleeve  92 , respectively, of a rubber tube gland  9  inserted through a back wall of the receptacle  3 . 
     In the interior of the receptacle  3 , the first coupling sleeve  91  is connected to a tube  13  extending to near the bottom of the receptacle, said tube  13  containing a filter that prevents limestone particles from being sucked through the pump  100 . The second sleeve  92  in turn is connected to a line  14  that extends the length of the receptacle  3  and comprises an end  14 A emerging vertically in the front part of the heat screen  4  at the level of the bottom of a cistern  15  borne by the top end of a water reservoir  16 , said cistern  15  being open at its top end such that a spillway for allowing the return of superfluous water to the receptacle  3  is formed. 
     The water reservoir  16  extends vertically to a height such that the bottom of the cistern  15  is located ca. 4 cm above the level of the bottom of the receptacle  3 , the cistern  15  comprising an orifice  15 A that communicates with a supply circuit for a drip valve  17  placed in the front part of the iron and emerging above the vaporization chamber  11  in a standard manner. 
     In this manner, the water fed to the cistern  15  by the pump  100  can then flow by gravity through the orifice  15 A in the water reservoir  16  in such a way as to supply the drip valve  17  for the generation of steam. The use of such a water reservoir  16  thus has the advantage of making it possible to obtain a constant water column height upstream from the drip valve  17 , enabling the generation of a substantial steam flow of around 40 to 50 g/min, regardless of the fill level of the receptacle  3 . 
     The flow rate of the piezoelectric pump  100  is preferably intended to be greater than the flow rate needed to generate 50 g/min of steam so that the generation of steam is not limited by the flow rate of the pump  100 , the superfluous water fed by the pump  100  to the water reservoir  16  emptying into the receptacle via the top opening of the cistern  15 . By way of an example, the mean flow rate of the bioelectric [sic] pump illustrated in the figures is around 100 ml/min. 
     In a manner known per se, the opening of the drip valve  17  is automatically controlled by a mechanical control system (not shown in the figures) relative to the temperature of the thermostat of the heating element  10  such that the amount of steam generated by the iron is automatically adjusted relative to the temperature, or to the type of fabric, selected by the user by means of the knob  8 . 
       FIGS. 4-6  are detailed illustrations of the piezoelectric pump equipping the clothing iron of  FIGS. 1-3 . 
     According to  FIGS. 5 and 6 , the piezoelectric pump  100  comprises a pumping chamber  110  that is defined by a support  101  and a movable wall  111  disposed face to face, the support  101  having a circular central zone bordered by a channel  112  that houses a gasket  113  on which the movable wall  111  will rest. The movable wall advantageously consists of a brass membrane  111  that comprises an outer surface oriented to the exterior of the pumping chamber  110 , on which is fastened a ceramic piezoelectric actuator  111 A. 
     The membrane  111  is held against the gasket  113  by means of a lid  102  fastened onto the support  101 , said lid  102  comprising a raised circular rib  120  that presses against the outer surface of the membrane  111  opposite the gasket  113 . The support  101  also houses a base plate  103  on the other side from the lid  102 , said base plate  103  supporting the delivery  131  and discharge  132  lines of the pump. 
     The support  101 , the lid  102 , and the base plate  103  are advantageously made of plastic reinforced with glass fibers, such as a polyarylamide with 30% glass fiber reinforcement, and are held together under stress by means of an elastic clip  104  in the form of a springy metal band that engages between guide ribs  123 ,  124  formed on the periphery of the lid  102  and of the base plate  103 , respectively. 
     The lid  102  comprises electric terminals  121 ,  122  that are electrically connected to the membrane  111  and to the piezoelectric actuator  111 A and powered, in a manner known per se, by an a.c. voltage bringing about a periodic deformation of the piezoelectric actuator  111 A and of the flexible membrane  111  in the direction for increasing and then decreasing the volume of the pumping chamber  110 . An example of a circuit for supplying power to the piezoelectric actuator is described in French patent application #08 01706. 
     In order to ensure electric insulation between the parts of the pump  100  subjected to an electric potential and the liquid contained in the pumping chamber  110 , the bottom face of the membrane  111  is coated with an insulating film  111 B consisting of three polyester films held together by means of an adhesive, as described in more detail in French patent application #08 03520. 
     More particularly according to the invention, the delivery  131  and discharge  132  lines emerge opposite an inlet  114  and an outlet  115  piercing the support  101 , respectively, and the pump  100  is placed vertically in the iron in such a way that the outlet  115  of the pumping chamber  110  is located at a higher level than the inlet  114  when the iron is in a normal operating position, i.e., resting on its sole  1 . 
     The inlet  114  is preferably placed substantially in the center of the pumping chamber  110  in such a way that it is located opposite the maximum clearance zone of the membrane  111 , where the depression is greatest. The outlet  115  in turn is preferably placed near the periphery of the pumping chamber  110 , the pump  100  being placed vertically in the iron such that the outlet  115  is located substantially at the top of the pumping chamber  110  when the iron is resting flat on its sole  1 . 
     In order to facilitate the expulsion of any air bubbles present in the pumping chamber, the dead volume of the pumping chamber  110  is essentially reduced to a groove  116  with a depth of around 1 mm extending between the inlet  114  and the outlet  115  on the face of the support  101  opposite the lid  102 , said groove  116  enabling the channeling of the air bubbles towards the outlet. 
     According to  FIG. 6 , the correct positioning of the lid  102  and of the base plate  103  on the support  101  is ensured by three centering tabs  117  borne by the support  101 , said centering tabs  117  cooperating with the periphery of the lid  102  and with notches  1036  on the periphery of the base plate  103 . 
     A silicone film  105  is interposed between the support  101  and the base plate  103  to form valves  151 ,  152  opposite the inlet  114  and the outlet  115 , the positioning of the film  105  on the base plate  103  being ensured by cut-outs  150  formed on the periphery of the film, wherein said cut-outs  150  engage around bosses  130  borne by the base plate  103 . 
     The valve  152  opposite the outlet  115  is preferably formed by an arc-shaped cut  152 A forming a flexible operculum opposite a circular recess  133  formed in the base plate  103 , said valve  152  opening in the recess  133  when water is compressed in the pumping chamber  110  and closing when the piezoelectric actuator  111 A bends in the direction for increasing the volume of the pumping chamber  110 . 
     Such a construction combined with a water reservoir  16  disposed downstream from the pump  100  has the advantage of enabling the creation a one-way valve in a very simple manner, wherein the presence of water in the line  14  creates a pressure downstream from the valve  152  that generates a check force proportional to the height of the water column tending to keep said valve  152  closed. Such a characteristic is particularly interesting because it prevents the water downstream from the valve  152  from flowing by gravity through the pump  100  and the receptacle  3  when the pump  100  is turned off. 
     The valve  151  opposite the inlet  114  is likewise formed by an arc-shaped cut  151 A forming a flexible operculum opposite a circular recess  118  formed in the support  101 , said valve  151  closing when the water in the pumping chamber  110  is compressed by the membrane  111  and opening when the piezoelectric actuator  111 A bends in the direction for increasing the volume of the pumping chamber  110 . 
     The vertical position of the pump  100  in the iron, with the outlet  115  located above the inlet  114 , has the advantage of enabling the formation of a water column downstream from the valve  152 , thus creating a pressure that generates a check force tending to keep said valve  152  closed. Such a characteristic makes it possible to keep the valve  152  closed when the pump  100  is turned off, without having to resort to a valve spring. 
     The arc-shaped cuts  151 A,  152 A preferably extend angularly less than 180° and are preferably aligned in the same direction so that a substantial width of material extends between said cuts  151 A,  152 A. Such a characteristic makes it possible to achieve good stability of the film  105  right next to said cuts  151 A,  152 A, significantly reducing the risk of the valves  151 ,  152  bending in the direction of opening when the film  105  is compressed between the support  101  and the base plate  103 . 
     The clothing iron thus configured has the advantage of possessing an efficient piezoelectric pump capable of expelling any air bubbles that may enter the pumping chamber, as the air bubbles have the natural tendency to be driven upwards towards the outlet by the water coming from the receptacle. An iron capable of generating a large amount of steam for high pressing efficiency and possessing stable performance characteristics over time is thus obtained. 
     Obviously the invention is in no way limited to the embodiment described and illustrated herein, which was merely provided as an example. Modifications are still possible, particularly in terms of the constitution of the various elements or by substituting technological equivalents, without exceeding the scope of protection of the invention in any way. 
     Hence the shape of the pumping chamber or the means of assembling the pump elements could be changed in a variant of embodiment of the invention.

Technology Category: d