Abstract:
The present invention provides a foamed-water generating aerator which is capable of generating good-quality foamed water containing fine, homogeneously distributed air bubbles. The foamed-water generating aerator ( 100 ) is fitted to a water discharge pipe to turn water being discharged into foamed water. A circumferential water flow curtain forming portion ( 110 ) includes a gap ( 111 ), through which water flows, and forms a three-dimensional circulating water flow curtain ( 112 ) in which an accelerated water-flow issuing downstream from the gap ( 111 ) is continuous in the circumferential direction. An air cavity ( 120 ) is provided at some intermediate point in a water-flow path as a place for forming the circulating water flow curtain ( 112 ) and sustains an air-filled condition even when a water-flow of the circulating water flow curtain enters therein. Air is drawn through an air ventilation hole ( 140 ) into an enclosed space, the enclosed space being defined by the circulating water flow curtain ( 112 ) formed in the air cavity ( 120 ) and a surrounding wall surface, is mixed with the circulating water flow curtain ( 112 ) to thereby form the foamed water.

Description:
TECHNICAL FIELD 
       [0001]    This invention relates to a foam water saving aerator attached to water delivery devices such as a water tap (including a general water tap and a special purpose water tap for laboratory use) and a shower head for saving the amount of the water flow and aerating the water for generating bubble foam water. 
       BACKGROUND ART 
       [0002]    Bubble foam water is required in many water taps including ordinary homes and in commercial facilities. The impression from use of the bubble foam water in washing is quite gentle. Therefore the bubble foam water is preferably used in washing glasses and the dishes because cracking or damage to the surface of the glasses and the dishes can be avoided. The bubble foam water hardly rebounds even if it hits the surface of the glasses and the dishes in washing, so there is no fear of splashing water around the sink and deteriorating the environment. Therefore, the bubble foam water preferably is used in many water taps not only in ordinary homes but also in the railway station, in the public facilities, in the laboratory in the research institute, and so on. 
         [0003]    In the prior art, one of the methods for making the bubble foam water is attaching a water saving aerator to the water delivery devices such as a water tap. The water saving aerator in the prior art comprises air ventilation holes for in taking outer air to the water flow as a basic structure. The outer air is mixed with the water flow via the air ventilation holes. In addition, the opening of the water delivery devices is covered by the net for cutting the water flow into small pieces. The bubble foam water is generated by mixing the outer air via air ventilation hole and cutting the water flow by installing several nets to the opening of the water delivery devices for cutting the water flow into small pieces.
   Patent prior art 1: JP H09-095985   Patent prior art 2: JP 2000-104300   
 
       DISCLOSURE OF THE INVENTION 
     The problems to be Solved 
       [0006]    The conventional water saving aerator described in the prior art has the following problem. The conventional water saving aerator can generate the bubble foam water including rough bubble, but it cannot generate the bubble foam water including a high quality fine bubble. The conventional water saving aerator supplies the outer air from the air ventilation holes located on the side wall to the water flow, so the outer air is mixed roughly in to the running water flow by being introduced from the side direction. The size of the involved bubble water is about several millimeters. After being introduced into water flow, the bubble is cut by a net or several nets into small pieces according to the water flow cutting. The bubble foam water is generated in this manner. 
         [0007]    However, the conventional water saving aerator described in the prior art generates the bubble foam water by mixing roughly the outer air into water flow only at the position where the outer air is supplied from the side direction. In addition, the hole of the net is about several millimeters as expected and cannot generate fine bubble smaller than the hole of the net. 
         [0008]    The first approach for generating the fine bubble foam in the conventional water saving aerator is based on increasing the contact area for outer air and water flow. However, it is impossible to increase the contact area in the horizontal direction if the outer air is supplied from the side direction to the water flow. It is possible to increase the contact area in the vertical direction since the length of the contact area with the air becomes large to the extent that the height of the water fall becomes large. Therefore, the amount of the mixing air becomes large. However, the vertical length of the apparatus becomes too large as the bubble foam water saving aerator to be attached to the water tap. 
         [0009]    The second approach for generating the fine bubble foam in the conventional water saving aerator is based on decreasing the mesh size of the net. However, the smaller the mesh size of the net becomes, the larger the resistance to the water flow becomes. The bubble mixed in the bubble foam water larger than the mesh size of the net in the upper stream does not pass through the mesh of the net easily. If the mesh size of the net reaches the sub-millimeter level, there is a risk that the bubble is blocked and remains inside of the water tap, and that the air ventilation via the air ventilation hole is obstructed. In addition, if the mesh size of the net reaches the sub-millimeter level, there is a risk that the suspended particle and contaminant remains and blocks the mesh of the net. 
         [0010]    If the mesh of the net wires double and triple in order to make the air bubbles in the foam water fine, scale and contaminants can be deposited easily and the water flow can be blocked. If the mesh of the net is blocked by the scale and contaminant, water flows out as normal water without forming a foam water, or water cannot flow out. In particular, such problem becomes readily apparent when the water quality is bad or the water hardness is high. 
         [0011]    Therefore, it is an object of the present invention to provide a foam water saving aerator that can generate the high quality babble foam water including fine bubbles uniformly. 
       Means for Solving the Problems 
       [0012]    In order to achieve the above-mentioned object, the present invention of a foam water saving aerator attached to the water tap for generating bubble foam water and flowing the bubble foam water comprises; a surrounding water flow curtain forming portion that includes a gap for flushing water flow, and forms a three-dimensional surrounding water flow curtain in which an accelerated water flow flushes downstream from the gap; an air cavity provided at an intermediate point of a water-flow route as a place for forming the surrounding water flow curtain that and sustains an air-filled condition even when a water flow of the surrounding water flow curtain flushes therein; a ventilation pass for supplying outer air to the shielded space shielded by the surrounding water flow curtain and supplying outer air to the water flow of the surrounding water flow curtain formed in the air cavity from the shielded space via an air ventilation hole; and a foamed water generating part for generating a foamed water by blowing the air through an air ventilation hole into the shielded space and mixing with the surrounding water flow curtain formed in the air cavity. 
         [0013]    The shield space provided by the surrounding water flow curtain generated dynamically in air cavity is not known in the conventional technology. Air will be mixed to the surrounding water flow curtain efficiently by the foamed water generating part, and the water curtain becomes a foamed water curtain efficiently. 
         [0014]    The foam water saving aerator can include a diffuser object installed in the point where the water flow of the surrounding water flow curtain hit, for diffusing the water flow of the surrounding water flow curtain to the direction for expanding the shielded space while sustaining the airtightness of the shielded space. The foam water can be generated by increasing the blowing of the air from the air ventilation hole by decreasing the air pressure at the expansion position of the shielded space by changing the water flow of the surrounding water flow curtain. 
         [0015]    When the air pressure in the shield space formed by the surrounding water flow curtain is decreased, the outer air is blown to the low air pressure shield space at a high speed via the ventilation pass. The air is injected to the surrounding water flow curtain efficiently, and forms a high quality foam water including rich fine bubbles and containing large volume of air. 
         [0016]    The shielded space is generated dynamically in the air cavity in a water flow, and the position of the shielded space can be both in an inner space of the surrounding water flow curtain and in an outer space between the surrounding water flow curtain and the wall of the air cavity. 
         [0017]    The first pattern is that the shielded space is an inner space of the surrounding water flow curtain. The foam water saving aerator can includes a diffuser object contacting the bottom surface of the surrounding water flow curtain and has skew to change the water flow direction of the surrounding water flow curtain to outside. When the water flow of the surrounding water flow curtain turns to the outside, the inner shielded space in the surrounding water flow curtain is expanded, so the air pressure is decreased at the point where the water flow of the surrounding water flow curtain hits the diffuser object. Therefore, a lot of air can be mixed to the surrounding water flow curtain from the inner shielded space especially at the point where the water flow of the surrounding water flow curtain hits the diffuser object. 
         [0018]    The second pattern is that the shielded space is an outer space between the surrounding water flow curtain and the wall of the air cavity. The diffuser object contacts the bottom surface of the surrounding water flow curtain and has skew to change the water flow direction of the surrounding water flow curtain to the center. When the water flow of the surrounding water flow curtain turns to the center, the outer space between the surrounding water flow curtain and the wall of the air cavity is expanded, so the air pressure is decreased at the point where the water flow of the surrounding water flow curtain hits the diffuser object. Therefore, a lot of air can be mixed to the surrounding water flow curtain from the outer shielded space especially at the point where the water flow of the surrounding water flow curtain hits the diffuser object. 
         [0019]    Various patterns of the shape of the gap in the surrounding water flow curtain forming portion and the shape of the formed water flow of the surrounding water flow curtain can be used. 
         [0020]    The first pattern is that the gap of the surrounding water flow curtain forming portion is a circumferential gap, and the shape of the surrounding water flow curtain flushed from the circulating gap becomes the cylinder shape. 
         [0021]    The second pattern is that the gap of the surrounding water flow curtain forming portion is a circumferential gap and has a taper with diameter becoming small according to the depth, wherein the shape of the surrounding water flow curtain flushed from the circulating gap becomes an inverted frustoconical shape. 
         [0022]    The third pattern is that the gap of the surrounding water flow curtain forming portion is a circumferential gap and has a taper with diameter becoming large according to the depth, wherein the shape of the surrounding water flow curtain flushed from the circulating gap becomes a frustoconical shape. 
         [0023]    There are other patterns except for the above three patterns. 
         [0024]    In either pattern, shield and airtightness in the bottom area of the inner shielded space should be maintained in order to enhance the airtightness of the inner shielded space formed by the surrounding water flow curtain and the wall of the air cavity. The airtightness of the shielded space should be maintained even when the foamed water generated in the shielded space runs out from the foam water outflow opening located on the bottom part of the shielded space. For this reason, the position, the shape and the size of the foam water outflow opening are modified as the outer air cannot ventilate directly via the foam water outflow opening, in order to keep the airtightness. If the running foamed water occupies and covers the whole area of the foam water outflow opening, the outer air cannot ventilate through the foam water outflow opening to the shielded space directly, the airtightness can be achieved. By prohibiting outer air ventilation via the foam water outflow opening, the airtightness of the shielded space can be maintained even when the foamed water runs out from the foam water outflow opening. 
         [0025]    Next, there are a variety patterns of the gap array in the surrounding water flow curtain forming portion. 
         [0026]    The gap array in the surrounding water flow curtain forming portion is not limited to the circumferential gap. For example, there are plural gaps arrayed in the circle, the accelerated water flows running down from the gaps are merged, the three-dimensional surrounding water flow curtain spread out in circle without the break in the space of the air cavity. If the three-dimensional surrounding water flow curtain spreads out in a circle without a break in the space of the air cavity, the gaps need not be connected to each other. 
         [0027]    Next, it is preferable that the water saving aerator further comprises a surrounding water flow curtain surface area variable mechanism for varying the shape and surface area of the surrounding water flow curtain generated dynamically in the air cavity; wherein the amount of the air mixed to the surrounding water flow curtain can be adjusted by varying the contact area between the surrounding water flow curtain and the supplied air. 
         [0028]    Next, it is also preferable that the water saving aerator further comprises a ventilation pass variable mechanism for varying the hole size of the ventilation pass and varying the speed of the air drawn from the ventilation pass wherein the speed of the air mixed to the surrounding water flow curtain can be adjusted. 
         [0029]    Next, it is also preferable that the water saving aerator further comprises a gap width variable mechanism for varying the gap width, wherein the thickness of the surrounding water flow curtain can be adjusted. 
       Effect of the Invention 
       [0030]    According to the above-mentioned configuration of the invention of the foamed water saving aerator can provide the shield space in the surrounding water flow curtain formed in the foamed water saving aerator. The outer air provided via the ventilation pass can be injected to the surrounding water flow curtain rapidly by utilizing the air pressure change in the inner space surrounded by the surrounding water flow curtain, so high quality foamed water including rich fine bubbles and containing large amounts of air can be generated. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0031]      FIG. 1  is a schematic view of the foamed water saving aerator  100  of the present invention in embodiment 1. 
           [0032]      FIG. 2  is an exploded view showing the configuration of the foamed water saving aerator  100  as the part  101 , the part  102 , and the part  103 . 
           [0033]      FIG. 3  is a schematic view showing a procedure for assembling the part  101 , the part  102 , and the part  103 . 
           [0034]      FIG. 4  is a schematic view showing an upper surface (surrounding water flow curtain forming portion  110 ) and lower surface (the ventilation path  140 , the foamed water outflow part  150 ) in the assembled state of the part  101  and the part  102 . 
           [0035]      FIG. 5  is a schematic view showing how foamed water is formed by injecting air from the inner space to the surrounding water flow curtain generated dynamically in the air cavity when the water is running through the foamed water saving aerator  100 . 
           [0036]      FIG. 6  is a schematic view of the foamed water saving aerator  100   a  of the present invention in embodiment 2. 
           [0037]      FIG. 7  is a schematic view of the status when the water is running through the foamed water saving aerator  100   a.    
           [0038]      FIG. 8  is a schematic view of another foamed water saving aerator  100   b  of the present invention in embodiment 2. 
           [0039]      FIG. 9  is a schematic view of the status when the water is running through the foamed water saving aerator  100   b.    
           [0040]      FIG. 10  is a schematic view of the foamed water saving aerator  100   c  of the present invention in embodiment 3. 
           [0041]      FIG. 11  is an exploded view showing the configuration of the foamed water saving aerator  100   c  as the part  101   c , the part  102   c , and the part  103   c.    
           [0042]      FIG. 12  is a schematic view of the status when the water is running through the foamed water saving aerator  100   c.    
           [0043]      FIG. 13  is a schematic view of the foamed water saving aerator  100   d  of the present invention in embodiment 4. 
           [0044]      FIG. 14  is an exploded view showing the configuration of the foamed water saving aerator  100   d  as the part  101   d , the part  102   d  and the part  103   d.    
           [0045]      FIG. 15  is a schematic view of the status when the water is running through the foamed water saving aerator  100   d.    
           [0046]      FIG. 16  is a schematic view of the foamed water saving aerator  100   e  of the present invention comprising a plurality of gaps in embodiment 5. 
           [0047]      FIG. 17  is a schematic view of the status when the water is running through the foamed water saving aerator  100   e.    
           [0048]      FIG. 18  is a schematic view of another foamed water saving aerator  100   f  of the present invention comprising a plurality of gaps in embodiment 5. 
           [0049]      FIG. 19  is a schematic view of the status when the water is running through the foamed water saving aerator  100   f.    
           [0050]      FIG. 20  is a schematic view of another foamed water saving aerator  100   g  comprising a ventilation pass variable mechanism for varying the hole size of the ventilation pass  141   g.    
           [0051]      FIG. 21  is a schematic view of another foamed water saving aerator  100   h  comprising a gap width variable mechanism for varying the gap width  111   h.    
       
    
    
     The Reference Number in the Figs 
       [0052]      100  denotes a foamed water saving aerator 
         [0053]      101  denotes a part 
         [0054]      102  denotes a part 
         [0055]      103  denotes a part 
         [0056]      110  denotes a surrounding water flow curtain forming portion 
         [0057]      111  denotes a gap 
         [0058]      112  denotes a surrounding water flow curtain 
         [0059]      113  denotes an inner space 
         [0060]      114  denotes an outer space 
         [0061]      120  denotes an air cavity 
         [0062]      130  denotes a diffuser object 
         [0063]      140  denotes an air ventilation pass 
         [0064]      141  denotes an air ventilation hole 
         [0065]      150  denotes a foam water outflow opening 
         [0066]      160  denotes an attachment part 
         [0067]      161  denotes a water cavity 
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0068]    Some embodiments of a foam water saving aerator according to the present invention are described below with reference to the relevant drawing. Needless to add, the claims of the present invention include but are not limited to the application, configuration, or quantity shown in the following embodiments. 
       Embodiment 1 
       [0069]    A schematic view of the foam water saving aerator  100  is shown as an example of this embodiment 1. The foam water saving aerator  100  shown in Embodiment 1 generates the surrounding water flow curtain as a cylindrical water flow curtain, and provides the inner space surrounded by the surrounding water flow curtain as the shielded space; and the diffuser object has a skew for expanding the water flow of the surrounding water flow curtain to outside. 
         [0070]    The foam water saving aerator  100  of the present invention comprises the surrounding water flow curtain forming portion  110 , the air cavity  120 , the diffuser object  130 , the air ventilation pass  140 , the attachment  160 , and the foam water outflow opening  150 .  FIG. 1  is a schematic view of the foamed water saving aerator  100 . In the configuration shown in  FIG. 1 , there are 3 parts, the part  101 , the part  102  and the part  103 .  FIG. 2  is an exploded view showing the configuration of the foamed water saving aerator  100  as the part  101 , the part  102 , and the part  103 .  FIG. 3  is a schematic view showing a procedure for assembling the part  101 , the part  102 , and the part  103 .  FIG. 4  is a schematic view showing an upper surface (surrounding water flow curtain forming portion  110 ) and lower surface (the ventilation path  140 , the foamed water outflow part  150 ) in the assembled state of the part  101  and the part  102 .  FIG. 5  is a schematic view showing how foamed water is formed by injecting air from the inner space to the surrounding water flow curtain  112  formed in the air cavity when the water supplied from the faucet  200  is running through the foamed water saving aerator  100 . 
         [0071]    In order to understand the internal structure easily,  FIG. 1 ,  FIG. 2 ,  FIG. 3  and  FIG. 5  are shown in the vertical cross sectional view. 
         [0072]    In this  FIG. 1 ,  FIG. 2 ,  FIG. 3  and  FIG. 5 , the foamed water saving aerator  100  is shown as a rotation body rotated around the vertical axis. However, the air ventilation hole  141  is not a rotation body but several holes opened in the wall defining the air ventilation pass  140  and connected to the inner shield space of the surrounding water flow curtain  112 . Also, the foam water outflow openings  150  are the several holes on the bottom area in order to release the water flow of the surrounding water flow curtain  112 . 
         [0073]    First, each component is described, then the mechanism is described for how foamed water is generated by introducing and mixing the outer air to the surrounding water flow curtain  112  formed when water flushes into the foamed water saving aerator from the faucet  200 . 
         [0074]    The part  101  is a rotation body as shown in  FIG. 2(   a ) and it is a tube-shaped membrane having a vertical cross sectional view as shown. 
         [0075]    There are an upper tubular body  1011 , a flange  1012 , a central tubular body  1013  and a lower tubular body  1014 , in which, a screw thread is provided at the inner wall of the lower tubular body  1014 . 
         [0076]    To reduce the number of components in this example, the structure of the surrounding water flow curtain forming portion  112  and air cavity  120  are provided by the part  101 . 
         [0077]    The part  102  comprises the disc body  1021  at the top and the tubular body  1022  beneath the disc body  1021 . The air ventilation pass  140  is formed in the tubular body  1022  and several holes are formed in the wall of the tubular body  1022 . These holes are the air ventilation holes  141 . The umbrella-shaped body  1023  is installed on the wall of the tubular body  1022 . This umbrella-shaped body  1023  is the diffuser object  130 . In addition, the disk  1024  is nearby the bottom of the tubular body  1022 . The tubular body  1022  and the disk  1024  are connected via the radial bridge as shown in  FIG. 4(   b ). The holes on the disk  1024  are the foam water outflow opening  150 . A screw thread is formed on the outer wall of the disk  1024 . 
         [0078]    To reduce the number of components in this example, the structure of the surrounding water flow curtain forming portion  110 , the air cavity  120 , the diffuser object  130  and the air ventilation pass  140  are provided by the part  101  and the part  102 . 
         [0079]    The part  103  is a rotation body as shown in  FIG. 2(   c ) and it is a tube-shaped membrane having a vertical cross sectional view as shown. There are the tubular body  1031 , and the hollow disk  1032  on the bottom of the tubular body  1031 . A screw thread is formed on the inner wall of the tubular body  1031 . This portion is the attachment  160  attached to the outer surface of the faucet  200 . The hollow disk  1032  of the part  103  is the component for locking the flange  1012  of the part  101 . 
         [0080]    Assembling of the part  101 , the part  102  and the part  103  is conducted as follows. First, the part  102  is inserted to the inside of the part  102  and the thread on the outer wall of the disk  1024  of the part  102  is screwed into the thread formed on the inner wall of the lower tubular body  1014  of the part  104  as shown in  FIG. 3(   a ). 
         [0081]      FIG. 4  is a schematic view showing upper surface and lower surface in the assembled state of the part  101  and the part  102 . 
         [0082]    In the assembled status where the part  101  is attached to the part  102 , the surrounding water flow curtain forming portion  110  is formed by the upper tubular body  1011  of the part  101  and the disk  1021  of the part  102  in the upper portion of the assembled state as shown in  FIG. 4(   a ). Both radiuses are adjusted to make the gap  111  between the inner wall of the upper tubular body  1011  of the part  101  and the outer wall of the disk  1021  of the part  102 . This gap  111  is provided as a part of the water flow route in the foamed water saving aerator  100 . 
         [0083]    In the assembled state where the part  101  is attached to the part  102 , the foam water outflow opening  150  is formed as the opening opened in the disk  1024  of the part  102  and the air ventilation pass  140  is formed on the inner wall of the central tubular body  1013  in the lower portion of the assembled status as shown in  FIG. 4(   b ). 
         [0084]    Next, the flange body  1012  of the part  101  is attached to the hollow disk  1032  of the part  103  in the assembled state with the part  101  attached to the part  102 , then the foamed water saving aerator  100  is assembled. Therefore, the part  101  and the part  102  are held by the part  103 . The state shown in  FIG. 1  is obtained by attaching the assembled foamed water saving aerator  100  to the faucet  200 . 
         [0085]    The foamed water saving aerator  100  is assembled as shown above. Next, each component of the foamed water saving aerator  100  is described. 
         [0086]    The surrounding water flow curtain forming portion  110  comprises a gap  111  as the water flow route and it injects the accelerated water flow from the gap  111  to the air cavity downstream and forms the three-dimensional surrounding water flow curtain in the air cavity space. 
         [0087]    In this configuration, the surrounding water flow curtain forming portion  110  is formed by the upper tubular body  1011  of the part  101  and the disk  1021  of the part  102 . The surrounding water flow curtain forming portion  110  has gap  111  connected to the air cavity  120  to inject the accelerated water flow from the water cavity  161 . The shape of the inner wall of the gap  111  determines the injection direction of the accelerated water flow and determines the shape of the surrounding water flow curtain  112  generated by the accelerated water flow. The gap  111  is provided between the inner wall of the upper tubular body  1011  of the part  101  and the outer wall of the disk  1021  of the part  102 . In this configuration shown in  FIG. 1 , the gap  111  of the surrounding water flow curtain forming portion  110  is formed vertically. 
         [0088]    If the water flow comes to the gap  111  of the surrounding water flow curtain forming portion  110  from the upper side, the surrounding water flow curtain  112  is formed downstream. The surrounding water flow curtain  112  becomes a three-dimensional water flow curtain spread out in a circle without a break in the space of the air cavity. The space of the air cavity is divided into the inner space  113  and the outer space  114  by the surrounding water flow curtain  112 . This surrounding water flow curtain  112  has no break, so the inner space  113  becomes the shield space having the airtightness. In the configuration shown in  FIG. 1 , the surrounding water flow curtain  112  becomes the cylinder shape as shown in  FIG. 5 . 
         [0089]    The water saving merit is achieved by the surrounding water flow curtain forming portion  110 . If the width of the gap  111  is smaller than the diameter of the water cavity  161 , the water flow is squeezed and the amount of the injected water flow from the gap  111  becomes small, so the water saving merit is obtained. The foamed water saving aerator  100  generates the high quality foamed water including a large amount of air by introducing a lot of air in the water flow, so the apparent volume of the injected foamed water from the foamed water saving aerator  100  becomes larger than the actual volume of the running water. The water use satisfaction of the user does not deteriorate. 
         [0090]    Next, the air cavity  120  is a space generated dynamically at an intermediate point of the water flow and filled with the air. It is provided as a space for generating the surrounding water flow curtain  112 . The air cavity  120  keeps on being filled with the air even if the water flow flushes into the air cavity and the surrounding water flow curtain  112  is generated. In this configuration, the air cavity  120  is provided as the space surrounded by the inner wall of the central tubular body  1013  of the part  101 , the outer wall of the tubular body  1022  of the part  102  and the upper surface of the umbrella-shaped body  1023 . 
         [0091]    The air ventilation holes  141  are formed in the air ventilation pass  140  located at the inner space side of the surrounding water flow curtain  112 , so the air is supplied from the outside. 
         [0092]    The diffuser object  130  is arrayed beneath the surrounding water flow curtain  112  generated in the air cavity  120 , and turns the direction of the water flow of the surrounding water flow curtain. In this configuration, the position and the angle of the diffuser object are adjusted to expand the surrounding water flow curtain to the outer direction. In this configuration, the umbrella-shaped body  1023  of the part  102  works as the diffuser object  130 . For example, the position of the diffuser object  130  is where the downstream edge of the generated a surrounding water flow curtain hits. The umbrella-shaped body  1023  is located at the impact position. The skew angle is the angle expanding to the outer direction from the center to turn the surrounding water flow curtain to the outer direction. The diffused water runs out from the foam water outflow opening  150 , which is the gap between the diffuser object  130  and the inner wall of the foamed water saving aerator. 
         [0093]    The air ventilation pass  140  is an air ventilation pass connected the shielded inner space  113  in the surrounding water flow curtain  112  and the outer air. The air ventilation hole  141  is located in the shielded inner space  113  of the surrounding water flow curtain  112 . In this configuration, the space of the tubular body  1022  of the part  102  is provided as the air ventilation pass  140 , and the plural holes opened in the wall of the tubular body  1022  are provided as the air ventilation holes  141 . 
         [0094]    The foam water outflow opening  150  is a portion of the water drain in which the foamed water flows downstream after hitting the diffuser object  130  and turning its direction. The foam water outflow opening  150  supplies the generated foamed water. In this configuration, the foam water outflow opening  150  is formed by two portions. One is the gap between the inner wall of the central tubular body  1013  of the part  101  and the umbrella-shaped body  1023  of the part  102 . The other is the holes located between the umbrella-shaped body  1023  of the part  102  and the disk  1024 . 
         [0095]    It is preferable that the position, shape and area are adjusted appropriately to keep the airtightness of the shielded inner space even while the foamed water is running out. The foam water generated in the shielded space runs out from the foam water outflow opening. Therefore, if the running foam water outflow occupies and covers the whole area of the foam water outflow opening, no air passage for the outside air exists in the shielded space via the foam water outflow opening. As a result, the airtightness of the shielded space is maintained even if the foam water runs through the shielded space and runs out from the foam water outflow opening. 
         [0096]    The attachment part  160  is a component for attaching to the faucet  200 . The attachment part  160  has a connecting portion whose inner diameter corresponds to the outer diameter of the faucet  200 . In this configuration, the thread is formed on the outer surface of the faucet  200 , and the thread is formed on the inner surface of the attachment  160 . The two are attached by screwing. Therefore, the attachment  160  connects firmly to the faucet  200  and does not disconnect even if the water pressure is supplied with an appropriate pressure. In addition, the attachment part  160  works as an input portion of the water input from the faucet  200 . In this example, there is a water cavity  161  filled with water in the inner of the attachment part  160 . In addition, the attachment  160  works as a tubular body wall surrounding the surrounding water flow curtain forming portion  110 . 
         [0097]    In this example, the inner space of the tubular body  1031  of the part  103  is the water cavity  161 . The female screw installed in the inner surface of the tubular body  1031  is a female screw screwed to the male screw installed in the outer wall of the faucet  200 . 
         [0098]    Next, the foamed water generating part in the foamed water saving aerator  100  is described. The foamed water generating part generates foamed water by blowing the air rapidly in the surrounding water flow curtain by decreasing the air pressure of the inner space. The air pressure is decreased at the point where the water flow is expanded in the outer direction by turning the water flow direction of the surrounding water flow curtain  112  with the diffuser object  130 . The mechanism of the foamed water generating part is described in detail. 
         [0099]      FIG. 5  is a schematic view showing the status when the water flow is running through the foamed water saving aerator  100  from the faucet  200 . As with  FIG. 1 ,  FIG. 5  is shown in the vertical cross sectional view in order to understand the internal water flow state easily. The water flow, the air flow and the generated foamed water are shown simply. 
         [0100]    The water supplied from the faucet  200  to the water cavity  161  is accepted on the upper surface of the surrounding water flow curtain forming portion  110  and the water goes down via the gap  111  by the water pressure of the water cavity  161 . The width of the gap  111  is smaller than the diameter of the water cavity  161 , so the water flow is squeezed and accelerated when running through the gap  111  and the water flow is injected to the air cavity  120 . In this configuration, the shape of the gap  111  is the circumferential shape, so the water flow accelerated by the gap  111  injected to the air cavity  120  becomes the three-dimensional cylinder shape as shown in  FIG. 5(   b ). 
         [0101]    In this example, the surrounding water flow curtain  112  has no break and spreads out in a circle. Therefore, the space of the air cavity  120  is divided into the inner shielded space  113  and the outer space  114  by the water flow curtain. The inner space  113  of the surrounding water flow curtain  112  maintains the airtightness, and it is provided as the shielded space filled with air. The outer space  114  is also filled with the air. 
         [0102]    In this configuration, as shown in  FIG. 5(   a ) and  FIG. 5(   b ), the diffuser object  130  is beneath the surrounding water flow curtain  112 , so the water flow of the surrounding water flow curtain  112  hits the diffuser object  130  and turns its direction to the outer direction. Therefore, the air pressure will decrease at the point where the water flow of the surrounding water flow curtain  112  hits the diffuser object  130  because the shielded space  113  is expanded. 
         [0103]    The water flow accelerated by the gap  111  runs rapidly downstream, and the air facing the water flow of the surrounding water flow curtain  112  is introduced. Especially, the air is rapidly introduced into the surrounding water flow curtain  112  where the air pressure is decreased by hitting the diffuser object  130  as shown in  FIG. 5(   a ), so a large amount of air is mixed and the high quality foamed water is obtained. The water flow becomes a flowing thin film and the air is introduced into the thin water flow curtain, so the bubble is spread out and diffused uniformly, and then the high quality foamed water is obtained. 
         [0104]    The outer air can be supplied from the air ventilation pass  140  via the air ventilation hole  141  because the air pressure in the shielded space  113 , and the air pressure around the air ventilation hole  141  are decreased in turn. 
         [0105]    Most conventional mechanisms of the foamed water aerator introduce the air by the air ventilation holes installed on the water flow pipe filled with water flow. However, the mechanism of the foamed water saving aerator  100  of the present invention has the air cavity  120  filled with the air even if the water flow runs through the air cavity  120 . The surrounding water flow curtain  112  is generated in the air cavity  120  and the shielded space with airtightness is provided by the water curtain. The present invention utilized a totally new idea of the air be rapidly injected to the water thin film by utilizing the air pressure decrease by changing the water flow direction of the surrounding water flow curtain. In addition, the foamed water saving aerator  100  of the present invention injects the air to the thin water flow curtain spread in the air cavity filled with the air, and high quality foamed water including a large amount of air can be obtained. 
         [0106]    The faster the accelerated water flow runs, the more the air pressure is decreased. So as the speed of the air injected to the water flow curtain becomes faster, the amount of the air mixed to the water flow curtain becomes larger. The air injected to the water flow curtain spreads out in the water flow curtain uniformly and changes into the fine bubbles. 
         [0107]    The generated foamed water runs from the diffuser object  130  to the foam water outflow opening  150 . The diffuser object  130  diffuses the accelerated water flow and can adjust the speed of the accelerated water flow appropriately for the washing hand water. This merit is called “the speed adjusting effect”. In addition, the diffuser object  130  can expand the diameter of the surrounding water flow curtain appropriately for the washing hand water. This merit is called “the water flow diameter adjusting effect”. As shown above, the speed and the diameter of the foamed water can be adjusted. 
         [0108]    As shown in  FIG. 5(   a ), the foamed water generated in the shielded space of the air cavity runs out from the foam water outflow opening  150 , which is the gap between the diffuser object  130  located in the bottom of the shielded space of the air cavity and the wall  1013 . The position, the shape and the area of the foam water outflow opening  150  are selected appropriately, so the whole area of the foam water outflow opening  150  is occupied and covered by the foamed water, and the outside air does not come from the foam water outflow opening  150 . The shielded space is not ventilated directly via the foam water outflow opening  150 . In this configuration, the airtightness of the shielded space can be maintained even while the generated foamed water flows out from the foam water outflow opening  150 . 
         [0109]    As shown above, according to the foamed water saving aerator of the embodiment 1, the surrounding water flow curtain  112  is generated in the air cavity and the inner space is supplied as the shielded space. The air is injected to the water thin film of the surrounding water flow curtain  112  by decreasing its air pressure by changing the water flow direction. High quality foamed water can be generated. 
       Embodiment 2 
       [0110]    Various shapes are available as the surrounding water flow curtain shape. Embodiment 2 shows several examples of how the surrounding water flow curtain is formed. One is an inverted frustoconical shape and the other is a frustoconical shape. In this embodiment 2, the inner space surrounded by the surrounding water flow curtain is provided as the shielded space, and the diffuser object has a skew for expanding the water flow of the surrounding water flow curtain to the outside. 
         [0111]      FIG. 6  is a schematic view of the foamed water saving aerator  100   a  of the present invention in embodiment 2 which generates the surrounding water flow curtain as the inverted frustoconical shape. 
         [0112]    As shown in  FIG. 6 , the foam water saving aerator  100   a  comprises the surrounding water flow curtain forming portion  110 , the air cavity  120 , the diffuser object  130 , the air ventilation pass  140 , the foam water outflow opening  150  and the attachment  160 . 
         [0113]    In order to understand the internal structure easily,  FIG. 6  is shown in the vertical cross sectional view. 
         [0114]    In the below description, for the same components as those shown in embodiment 1, the explanation is omitted in this embodiment 2. 
         [0115]    As shown in  FIG. 6 , the surrounding water flow curtain forming portion  110   a  comprises the gap  111   a  for accelerating and flushing the water from the water cavity  161  to the air cavity  120 . The gap  111   a  is a circumferential gap and has a taper whose diameter becomes small according to the depth. As shown in  FIG. 6 , the gap  111   a  has a skew to the center. 
         [0116]    The shape of the inner wall of the gap  111   a  determines the injection direction of the accelerated water flow and determines the shape of the surrounding water flow curtain  112   a  generated by the accelerated water flow. In this configuration, the surrounding water flow curtain  112   a  becomes the inverted frustoconical shape water flow curtain. The water flow curtain divides the inner space  113  of the surrounding water flow curtain  112   a  and the outer space  114 , and the inner space  113  of the surrounding water flow curtain  112   a  becomes the shielded space whose airtightness is maintained. 
         [0117]      FIG. 7(   a ) is a schematic view of the state when the water is running through the foamed water saving aerator  100   a . The same as  FIG. 6 ,  FIG. 7(   a ) is shown in the vertical cross sectional view in order to understand the internal structure easily.  FIG. 7(   a ) shows the water flow, the air flow and the generated foamed water simply. 
         [0118]    The water supplied from the faucet  200  to the water cavity  161  is accepted on the upper surface of the surrounding water flow curtain forming portion  110   a  and the water goes down via the gap  111   a  by the water pressure of the water cavity  161 . The gap  111   a  is a circumferential gap and has a taper whose diameter becomes small according to the depth, so the accelerated water flow flushed into the air cavity  120  becomes the three-dimensional inverted frustoconical shape. In this configuration, the diffuser  130   a  is installed on the bottom of the surrounding water flow curtain  112   a.    
         [0119]    In the configuration shown in  FIG. 7(   a ) and  FIG. 7(   b ), this surrounding water flow curtain  112   a  has no break, so the air cavity is divided into the inner space  113  and outer space  114  by the surrounding water flow curtain  112   a . The inner space  113  becomes the shield space having airtightness. 
         [0120]    The inner space  113  of the surrounding water flow curtain  112   a  keeps airtightness, and it is provided as the shielded space filled with the air. The outer space  114  of the surrounding water flow curtain  112   a  is also filled with the air. 
         [0121]    The mechanism of the air injection to the surrounding water flow curtain  112   a  generated by the water flow flushed from the gap  111   a  is the same as that of the embodiment 1. 
         [0122]    In this configuration, as shown in  FIG. 7(   a ) and  FIG. 7(   b ), there is the diffuser object  130   a  beneath the surrounding water flow curtain  112   a , so the water flow of the surrounding water flow curtain  112   a  hits the diffuser object  130   a  and turns its direction to the outer direction. Therefore, the air pressure will decrease at the point where the water flow of the surrounding water flow curtain  112   a  hits the diffuser object  130   a  because the shielded space  113  is expanded at this point. 
         [0123]    The water flow accelerated by the gap  111   a  runs rapidly downstream, so the air facing the water flow of the surrounding water flow curtain  112   a  is introduced. Especially, the air is rapidly introduced into the surrounding water flow curtain  112   a  where the air pressure is decreased by hitting the diffuser object  130   a  as shown in  FIG. 7(   a ), so a large amount of air is mixed and the high quality foamed water is obtained. The water flow becomes a thin water flow curtain and the air is introduced into the thin water flow curtain, so the bubble is spread out and diffused uniformly, and then the high quality foamed water is obtained. 
         [0124]    The generated foamed water runs from the diffuser object  130   a  to the foam water outflow opening  150 . 
         [0125]    As shown in  FIG. 7(   a ), the foamed water generated in the shielded space of the air cavity runs out from the foam water outflow opening  150   a  which is the gap between the diffuser object  130   a  located in the bottom of the shielded space of the air cavity and the wall  1013 . Because whole area of the foam water outflow opening  150   a  is occupied and covered by the foamed water, the outer air does not come from the foam water outflow opening  150   a . The shielded space does not ventilate directly via the foam water outflow opening  150   a . In this configuration, the airtightness of the shielded space can be maintained even while the generated foamed water flows out from the foam water outflow opening  150   a.    
         [0126]    As show above, the surrounding water flow curtain  112   a  is generated as the inverted frustoconical shape by modifying the shape of the gap  111   a  of the surrounding water flow curtain forming portion  110   a , and the air pressure is decreased by changing the flow direction of the water flow, and the high quality foamed water can be generated by rapid injection of the air to the surrounding water flow curtain  112   a.    
         [0127]    Next, the other example is described. 
         [0128]      FIG. 8  is a schematic view of another foamed water saving aerator  100   b  of the present invention in embodiment 2, which generates the surrounding water flow curtain as the frustoconical shape. 
         [0129]    As shown in  FIG. 8 , the foam water saving aerator  100   b  comprises the surrounding water flow curtain forming portion  110   b , the air cavity  120 , the diffuser object  130 , the air ventilation pass  140 , the foam water outflow opening  150  and the attachment  160 . 
         [0130]    In order to understand the internal structure easily,  FIG. 8  is shown in the vertical cross sectional view. 
         [0131]    As shown in  FIG. 8 , the surrounding water flow curtain forming portion  110   b  comprises the gap  111   b  for accelerating and flushing the water from the water cavity  161  to the air cavity  120 . The gap  111   b  is a circumferential gap and has a taper whose diameter becomes large according to the depth. As shown in  FIG. 8 , the gap  111   b  has skew to the outside. 
         [0132]    The shape of the inner wall of the gap  111   b  determines the injection direction of the accelerated water flow and determines the shape of the surrounding water flow curtain  112   b  generated by the accelerated water flow. In this configuration, the surrounding water flow curtain  112   b  becomes the frustoconical shape water flow curtain. The water flow curtain defines the inner space  113  of the surrounding water flow curtain  112   b  and the outer space  114 , and the inner space  113  of the surrounding water flow curtain  112   b  becomes the shielded space whose airtightness is maintained. 
         [0133]      FIG. 9(   a ) is a schematic view of the state when the water is running through the foamed water saving aerator  100   b . The same as  FIG. 5 ,  FIG. 9(   a ) is shown in the vertical cross sectional view in order to understand the internal structure easily.  FIG. 9(   a ) shows the water flow, the air flow and the generated foamed water simply. 
         [0134]    The water supplied from the faucet  200  to the water cavity  161  is accepted on the upper surface of the surrounding water flow curtain forming portion  110   b  and the water goes down via the gap  111   b  by the water pressure of the water cavity  161 . The gap  111   b  is a circumferential gap and has a taper whose diameter becomes large according to the depth, so the accelerated water flow flushes into the air cavity  120  and becomes the frustoconical shape. In this configuration, the diffuser  130   b  is installed on the bottom of the surrounding water flow curtain  112   b , and the airtightness improves by sealing the bottom of the surrounding water flow curtain  112   b.    
         [0135]    In the configuration shown in  FIG. 9(   a ) and  FIG. 9(   b ), this surrounding water flow curtain  112   b  has no break, so the air cavity is divided into the inner space  113  and outer space  114  by the surrounding water flow curtain  112   b . The inner space  113  becomes the shield space having the airtightness. 
         [0136]    The mechanism of the air injection to the surrounding water flow curtain  112   b  generated by the water flow flushed from the gap  111   b  is the same as that of the embodiment 1. 
         [0137]    In this configuration, as shown in  FIG. 9(   a ) and  FIG. 9(   b ), the diffuser object  130   b  is beneath the surrounding water flow curtain  112   b , so the water flow of the surrounding water flow curtain  112   b  hits the diffuser object  130   a  and turns its direction to the outer direction. Therefore, the air pressure will decrease at the point where the water flow of the surrounding water flow curtain  112   b  hits the diffuser object  130   b  because the shielded space  113  is expanded. 
         [0138]    The water flow accelerated by the gap  111   b  runs rapidly downstream, and the air facing with the water flow of the surrounding water flow curtain  112   b  is introduced. Especially, the air is rapidly introduced into the surrounding water flow curtain  112   b  where the air pressure is decreased by hitting the diffuser object  130   b  as shown in  FIG. 9(   a ), so a large amount of air is mixed and the high quality foamed water is obtained. The water flow becomes a thin water flow curtain and the air is introduced into the thin water flow curtain, so the bubbles are spread out and diffused uniformly, and the high quality foamed water is obtained. 
         [0139]    The generated foamed water runs from the diffuser object  130   a  to the foam water outflow opening  150 . 
         [0140]    As shown in  FIG. 9(   a ), the foamed water generated in the shielded space of the air cavity runs out from the foam water outflow opening  150   b , which is the gap between the diffuser object  130   b  and the wall  1013 . Because the whole area of the foam water outflow opening  150   b  is occupied and covered by the foamed water, the outside air does not come from the foam water outflow opening  150   b . The shielded space is not ventilated directly via the foam water outflow opening  150   b . In this configuration, the airtightness of the shielded space can be maintained even while the generated foamed water flows out from the foam water outflow opening  150   b.    
         [0141]    As show above, the surrounding water flow curtain  112   b  is generated as the frustoconical shape by modifying the shape of the gap  111   b  of the surrounding water flow curtain forming portion  110   b , and the air pressure is decreased by changing the flow direction of the water flow, and the high quality foamed water can be generated by rapid injection of the air to the surrounding water flow curtain  112   b.    
         [0142]    As shown above, the area of the surrounding water flow curtain  112  generated in the air cavity  120  can be modified according to the shape of the surrounding water flow curtain  112 . As a result, the contacting area of the surrounding water flow curtain  112  and the air, and the amount of the air introduced into the surrounding water flow curtain  112  can be changed. The amount of air in the foamed water can be adjusted by controlling the shape of the surrounding water flow curtain  112 . In this specification, the mechanism for controlling the area of the surrounding water flow curtain  112  generated in the air cavity  120  is called “surrounding water flow curtain surface area variable mechanism”. It is not limited how to configure the mechanism for varying the shape of the surrounding water flow curtain formed in the air cavity and varying the surface area of the surrounding water flow curtain. For example, the skew of the gap  111  of the surrounding water flow curtain forming portion  110  can be modified by a slide mechanism or a screw mechanism. For example, the slide mechanism or screw mechanism is installed in order to adjust the shape of the surrounding water flow curtain forming portion  110  shown in  FIG. 1  and  FIG. 5 , the surrounding water flow curtain forming portion  110   a  shown in  FIG. 6  and  FIG. 7 , and the surrounding water flow curtain forming portion  110   b  shown in  FIG. 8  and  FIG. 9 . 
         [0143]    The area of the surrounding water flow curtain  112  generated in the air cavity  120  can be controlled by the mechanism for modifying the height of the diffuser object  130 . Therefore, such a mechanism for modifying the height of the diffuser object  130  can be utilized as the “surrounding water flow curtain surface area variable mechanism”. 
       Embodiment 3 
       [0144]    The above-mentioned Embodiment 2 shows the foamed water saving aerator configuration in which the shielded space is an outer space between the surrounding water flow curtain and the wall of the air cavity, and the diffuser object has a skew to collect the water flow to the center. 
         [0145]    In the following description in embodiment 3, the description for the components that are the same as those of the embodiment 1 is omitted hereinafter; the description for the component which are not employed in embodiment 1 is emphasized. 
         [0146]      FIG. 10  is a schematic view of the foamed water saving aerator  100   c  that generates the surrounding water flow curtain as the cylinder shape. 
         [0147]    As shown in  FIG. 10 , the foam water saving aerator  100   c  comprises the surrounding water flow curtain forming portion  110   c , the air cavity  120 , the diffuser object  130   c , the air ventilation pass  140   c , the foam water outflow opening  150  and the attachment  160 . In order to understand the internal structure easily,  FIG. 10  is shown in the vertical cross sectional view. 
         [0148]    As shown in the exploded configuration in  FIG. 11 , there are 3 parts; the part  101   c , the part  102   c  and the part  103   c  are combined. 
         [0149]    In this configuration, the surrounding water flow curtain forming portion  110   c  is formed in the upper portion of the part  101  and the part  102 . The shape of the inner wall of the surrounding water flow curtain forming portion  110   c  is the same as that of the embodiment 1. The surrounding water flow curtain  112   c  is generated in the air cavity  120  as the cylinder-shape closed water flow curtain the same as the surrounding water flow curtain  112  shown in  FIG. 5 . 
         [0150]    The air cavity  120   c  is provided as the space surrounded by the inner wall of the central tubular body  1013   c  of the part  101   c  and the outer wall of the tubular body  1022   c  of the part  102   c.    
         [0151]    The diffuser object  130   c  is different from the diffuser object  130  shown in  FIG. 1 . It is provided as the part  1016   c  of the part  101   c  and attached to the inner wall of the air cavity with a skew descending from the periphery side to the central side. 
         [0152]    The air ventilation pass  140   c  is formed in the part  102   c  side. It is different from that of embodiment 1. In this configuration, the air ventilation pass  140   c  is formed among the part  1013   c  of the part  102   c , the part  1014   c  and the part  1015   c  to ventilate the outside air. 
         [0153]      FIG. 12(   a ) is a schematic view showing the state when the water flow is running through the foamed water saving aerator  100   c  from the faucet  200 . As in  FIG. 5 , it is shown in the vertical cross sectional view in order to understand the internal water flow status easily. The water flow, the air flow and the generated foamed water are shown simply. 
         [0154]    The water supplied from the faucet  200  to the water cavity  161  is accepted on the upper surface of the surrounding water flow curtain forming portion  110   c  and the water goes downs via the gap  111   c  by the water pressure of the water cavity  161 . The accelerated water flow generates the three-dimensional surrounding water flow curtain  112   c  as shown in  FIG. 5(   b ). 
         [0155]    As shown in  FIG. 12(   a ) and  FIG. 12(   b ), this surrounding water flow curtain  112   c  has no break, so the air cavity  120  is divided into the inner space  113  and outer space  114  by the surrounding water flow curtain  112   c . The outer space  114  of the surrounding water flow curtain  112   c  is surrounded by the surrounding water flow curtain  112   c  and the wall  1013   c , so the outer space  114  becomes the shield space having the airtightness. 
         [0156]    The outer space  114  of the surrounding water flow curtain  112   c  keeps air tightness, and is provided as the shielded space filled with the air. The inner space  113  of the surrounding water flow curtain  112   c  is also filled with the air. 
         [0157]    The mechanism of the air injection to the surrounding water flow curtain  112   c  generated by the water flow flushed from the gap  111   c  is the same as that of the embodiment 1. 
         [0158]    In this configuration, as shown in  FIG. 12(   a ) and  FIG. 12(   b ), there is the diffuser object  130   c  beneath the surrounding water flow curtain  112   c , so the water flow of the surrounding water flow curtain  112   c  whose shape is cylindrical hits the diffuser object  130   c  and turns its direction to center direction. Therefore, the air pressure will decrease at the point where the water flow of the surrounding water flow curtain  112   c  hits the diffuser object  130   c  because the shielded outer space  114  is expanded at this point. 
         [0159]    The water flow accelerated by the gap  111   c  runs rapidly downstream, and the air facing with the water flow of the surrounding water flow curtain  112   c  is introduced. Especially, the air is rapidly introduced into the surrounding water flow curtain  112   c  where the air pressure is decreased by hitting the diffuser object  130   c  as shown in  FIG. 12(   a ), so a large amount of air is mixed and the high quality foamed water is obtained. The water flow becomes a thin water flow curtain and the air is introduced into the thin water flow curtain, so the bubbles are spread out and diffused uniformly, and then the high quality foamed water is obtained. 
         [0160]    The generated foamed water runs from the diffuser object  130   c  to the foam water outflow opening  150   c.    
         [0161]    As shown in  FIG. 12(   a ), the foamed water generated in the shielded space of the air cavity runs out from the foam water outflow opening  150   c , which is the gap between the diffuser object  130   c  and the wall  1013 . Because whole area of the foam water outflow opening  150   c  is occupied and covered by the foamed water, the outside air does not come from the foam water outflow opening  150   c . The shielded space is not ventilated directly via the foam water outflow opening  150   c . In this configuration, the airtightness of the shielded space can be maintained even while the generated foamed water flows out from the foam water outflow opening  150   c.    
       Embodiment 4 
       [0162]    Embodiment 4 shows the foamed water saving aerator configuration, in which, the surrounding water flow curtain is the frustoconical shape, the shielded space is an outer space between the surrounding water flow curtain and the wall of the air cavity, and the diffuser object is the wall attached to the wall of the air cavity. The diffuser object has a skew to turn the water flow of the surrounding water flow curtain to downward. 
         [0163]    In the following description in embodiment 4, the description for the components which are the same as those of embodiment 1 is omitted hereinafter; the description for the components which are not employed in embodiment 1 is emphasized. 
         [0164]      FIG. 13  is a schematic view of the foamed water saving aerator  100   d  which generates the surrounding water flow curtain as the frustoconical shape. 
         [0165]    As shown in  FIG. 13 , the foam water saving aerator  100   d  comprises the surrounding water flow curtain forming portion  110   d , the air cavity  120 , the diffuser object  130   d , the air ventilation pass  140   d , the foam water outflow opening  150  and the attachment  160 . In order to understand the internal structure easily,  FIG. 13  is shown in the vertical cross sectional view. 
         [0166]    As shown in the exploded configuration in  FIG. 14 , there are 3 parts; the part  101   c , the part  102   c  and the part  103   c  are combined. 
         [0167]    In this configuration, the surrounding water flow curtain forming portion  110   d  is formed in the upper portion of the part  101  and the part  102 . The shape of the inner wall of the surrounding water flow curtain forming portion  110   d  is the same as that of the embodiment 2. The surrounding water flow curtain  112   d  is generated in the air cavity  120  as the frustoconical shape closed water flow curtain the same as the surrounding water flow curtain  112  shown in  FIG. 9 . 
         [0168]    The air cavity  120   d  is provided as the space surrounded by the inner wall of the central tubular body  1013   d  of the part  101   d  and the outer wall of the tubular body  1022   d  of the part  102   d.    
         [0169]    The diffuser object  130   d  is different from the diffuser object  130  shown in  FIG. 1 , and it is provided as the part attached to the part  101   c . The wall  1013   d  works as a part of the wall of the air cavity  120  and also works as the diffuser object  130   d . In this configuration, the diffuser object  130   d  is a simple vertical wall, but it can turn the water flow, which is flushed from the center to the periphery side, downward. 
         [0170]    In this configuration, as shown in  FIG. 14 , the umbrella-shaped object  1025   d  is attached to the part  102   d . This umbrella-shaped object  1025   d  is different from the diffuser object. The surrounding water flow curtain does not hit the umbrella-shaped object  1025   d  directly, and it can seal the bottom surface of the air cavity  120 . 
         [0171]    The air ventilation pass  140   d  is formed in the part  102   d  side the same as embodiment 3. In this configuration, the air ventilation pass  140   d  is formed among the part  1013   d  of the part  102   d , the part  1014   d  and the part  1015   d  to ventilate the outer air. 
         [0172]      FIG. 15(   a ) is a schematic view showing the state when the water flow is running through the foamed water saving aerator  100   d  from the faucet  200 . As with  FIG. 5(   a ), it is shown in the vertical cross sectional view in order to understand the internal water flow state easily. The water flow, the air flow and the generated foamed water are shown simply. 
         [0173]    The water supplied from the faucet  200  to the water cavity  161  is accepted on the upper surface of the surrounding water flow curtain forming portion  110   d  and the water goes downs via the gap  111   d  by the water pressure of the water cavity  161 . The accelerated water flow generates the frustoconical shape surrounding water flow curtain  112   d  as shown in  FIG. 15(   b ). 
         [0174]    As shown in  FIG. 15(   a ) and  FIG. 15(   b ), this surrounding water flow curtain  112   d  has no break, so the air cavity  120  is divided into the inner space  113  and outer space  114  by the surrounding water flow curtain  112   d . The outer space  114  of the surrounding water flow curtain  112   d  is surrounded by the surrounding water flow curtain  112   d  and the wall  1013   d , so the outer space  114  becomes the shield space having the airtightness. 
         [0175]    The outer space  114  of the surrounding water flow curtain  112   d  keeps the airtightness, and it is provided as the shielded space filled with the air. The inner space  113  of the surrounding water flow curtain  112   d  is also filled with the air. 
         [0176]    The mechanism of the air injection to the surrounding water flow curtain  112   d  generated by the water flow flushed from the gap  111   d  is the same as that of the embodiment 1. In the embodiment 1, the air is injected to the surrounding water flow curtain from the inner space  113 , but in this embodiment 4, the air is injected to the surrounding water flow curtain from the outer space  114 . The air injection direction is opposite 
         [0177]    In this configuration, as shown in  FIG. 15(   a ) and  FIG. 15(   b ), the water flow of the surrounding water flow curtain  112   d  flushes outward, and there is a wall of the part  1013   d  in front of the flushing water. This wall of the part  1013   d  works as the diffuser object  130   d . The water flow of the frustoconical shape surrounding water flow curtain  112   d  turns downward by hitting the diffuser object  130   d . Therefore, the air pressure will decrease at the point where the water flow of the surrounding water flow curtain  112   d  hits the diffuser object  130   d  because the shielded outer space  114  is expanded downwardly. 
         [0178]    The water flow accelerated by the gap  111   d  runs rapidly downstream, and the air facing with the water flow of the surrounding water flow curtain  112   d  is introduced. Especially, the air is rapidly introduced into the surrounding water flow curtain  112   d  at the point where the water flow turns downward by hitting the diffuser object  130   c  and the air pressure is decreased as shown in  FIG. 12(   a ), so a large amount of air is mixed and the high quality foamed water is obtained. The water flow becomes a thin water flow curtain and the air is introduced into the thin water flow curtain, so the bubbles are spread out and diffused uniformly, and the high quality foamed water is obtained. 
         [0179]    The generated foamed water runs from the gap between the part  1025   d  and the wall  1013   d  to the foam water outflow opening  150   d.    
         [0180]    As shown in  FIG. 15(   a ), the foamed water generated in the shielded space of the air cavity runs out from the foam water outflow opening  150   c  which is the gap between the part  1025   d  and the wall  1013   d . Because the whole area of the foam water outflow opening  150   d  is occupied and covered by the foamed water, the outside air does not come from the foam water outflow opening  150   d . The shielded space is not ventilated directly via the foam water outflow opening  150   d . In this configuration, the airtightness of the shielded space can be maintained even while the generated foamed water flows out from the foam water outflow opening  150   d.    
       Embodiment 5 
       [0181]    Embodiment 5 shows the foamed water saving aerator configuration, in which there are several gaps in the surrounding water flow curtain forming portion, and the accelerated water flows flushed from the gaps are merged and form the three-dimensional surrounding water flow curtain generated in the air cavity space. 
         [0182]    There are several patterns and arrangement of the gaps in the surrounding water flow curtain forming portion. 
         [0183]      FIG. 16  is a schematic view of the surrounding water flow curtain forming portion  110   e  comprising a plurality of gaps of the present invention in embodiment 5.  FIG. 16(   a ) is a cross sectional horizontal view of the upper portion of the surrounding water flow curtain forming portion  110   e ,  FIG. 16(   b ) is a cross sectional horizontal view of the bottom portion of the surrounding water flow curtain forming portion  110   e.    
         [0184]    The surrounding water flow curtain forming portion  110   e  comprises plural gaps  111   e  arrayed in a circle. In this example, there are 8 gaps, which are from the gap  111   e   1  to the gap  111   e   8  arrayed in a circle. 
         [0185]    For example, each gap  111   e  may have the vertical wall without skew or may have the skewed wall whose length becomes large according to the depth. 
         [0186]      FIG. 17(   a ) is a schematic view showing the status when the water flow is running through the foamed water saving aerator  100   e  from the faucet  200 . As shown in  FIG. 17(   a ), the accelerated water flow flushes from each gap  111   e   1  to gap  111   e   8  as the curtain-shaped water flow, and the flushing water flow merges and is superimposed as the three-dimensional surrounding water flow curtain  112   e . In this embodiment, as shown  FIG. 17 , there is a small break in the upper portion of the surrounding water flow curtain  112   e . The flushing segments of the curtain-shaped water flow close to each other, and are drawn toward each other to form a merged flow. The flushing water flow smoothly merges immediately, so the three-dimensional surrounding water flow curtain  112   e  without break is generated as a whole. In this invention, it is preferable that the three-dimensional surrounding water flow curtain  112  without break perfectly, but the three-dimensional surrounding water flow curtain with very small breaks or very small hole in the water flow curtain can work as the surrounding water flow curtain  112  for providing the shielded space. 
         [0187]    The curtain-shaped water flow is provided as the wall substantially without break the same as embodiment 1, the water flow curtain divides the air cavity  120  into the inner space  113   e  of the surrounding water flow curtain  112   e  and the outer space  114   e , and the inner space  113   e  of the surrounding water flow curtain  112   e  becomes the shielded space whose airtightness is maintained. 
         [0188]    The mechanism of the air injection to the surrounding water flow curtain  112   e  generated by the water flow flushed from the surrounding water flow curtain forming portion  110   e  is the same as that of the embodiment 1. 
         [0189]    Next, the surrounding water flow curtain forming portion  110   f  comprises a plurality of gaps having a different pattern from that shown in  FIG. 16 .  FIG. 18(   a ) is the horizontal cross sectional view of the upper portion of the surrounding water flow curtain forming portion  110   f ,  FIG. 18(   b ) is the horizontal cross sectional view of the bottom portion of the surrounding water flow curtain forming portion  110   f.    
         [0190]    As shown in  FIG. 18(   a ) and  FIG. 18(   b ), the surrounding water flow curtain forming portion  110   f  provides a plurality of gaps  111   f  arrayed in a circle. In this example, there are  8  gaps, which are from the gap  111   f   1  to the gap  111   f   8 , arrayed in a concentric double circle. There are the outer line and the inner line. The outer line includes the gap  111   f   1  to the gap  111   f   4 , the inner line includes the gap  111   f   5  to the gap  111   f   8 . 
         [0191]    For example, the gap  111   f   1  to the gap  111   f   4  has the vertical wall without skew in depth, and the gap  111   f   5  to the gap  111   f   8  have the skewed wall with taper to the outside according to the depth. Therefore, the setting of the gap  111   f   1  to the gap  111   f   4  and the setting of the gap  111   f   5  to the gap  111   f   8  are close to each other in the lower position. It is preferable that the taper is adjusted for assisting the water flow curtain flushed from the gap  111   f   1  to the gap  111   f   4  and the water flow curtain flushed from the gap  111   f   5  to the gap  111   f   8  to merge and generate the whole surrounding water flow curtain  112   e.    
         [0192]      FIG. 19  is a schematic view showing the state when the water flow is running through the foamed water saving aerator  100   f  from the faucet  200 . As shown in  FIG. 19 , the accelerated water flow flushes from each gap  111   f   1  to gap  111   f   8  as the curtain-shaped water flow, and the flushing water flow merges and is superimposed as the three-dimensional surrounding water flow curtain  112   f . In this embodiment, as shown  FIG. 19 , there is a small break in the upper portion of the surrounding water flow curtain  112   f . However, the angle of the flushing curtain-shaped water flow is adjusted as the angle that allows the flushing curtain-shaped water flow to merge easily. In addition, the flushing curtain-shaped water flow close near to each other, so each flushing curtain-shaped water flow pulls physically each other and merged. The flushing water flow smoothly merged immediately, so the three-dimensional surrounding water flow curtain  112   f  without break is generated as a whole. In this invention, the three-dimensional surrounding water flow curtain with very small breaks or very small hole in the water flow curtain can work as the surrounding water flow curtain for providing the shielded space. 
         [0193]    The curtain-shaped water flow is provided as the wall substantially without break the same as embodiment 1, the water flow curtain divides the air cavity  120  into the inner space  113   f  of the surrounding water flow curtain  112   f  and the outer space  114   f , and the inner space  113   f  of the surrounding water flow curtain  112   f  becomes the shielded space whose airtightness is maintained. 
         [0194]    The mechanism of the air injection to the surrounding water flow curtain  112   f  generated by the water flow flushed from the surrounding water flow curtain forming portion  110   f  is the same as that of the embodiment 1. 
         [0195]    As shown above, according to the foamed water saving aerator  100   e  and  100   f  of the embodiment 5, the surrounding water flow curtain is generated in the air cavity and the inner space is provided as the shielded space. The air is injected to the water thin film of the surrounding water flow curtain by decreasing its air pressure by the curtain-shape water flow. High quality foamed water can be generated. 
       Embodiment 6 
       [0196]    Embodiment 6 shows the foamed water saving aerator configuration, in which there is a ventilation pass variable mechanism for varying the hole size of the ventilation pass and varying the speed of the air drawn from the ventilation pass, wherein the speed of the air mixed to the surrounding water flow curtain can be adjusted. 
         [0197]      FIG. 20  is a schematic view of the foamed water saving aerator  100   g  comprising a ventilation pass variable mechanism for varying the hole size of the ventilation pass  141   g . The ventilation pass variable mechanism can be applied to any of the foamed water saving aerators  100  shown in embodiment 1 to embodiment 5. For example, the ventilation pass variable mechanism applied to foamed water saving aerator shown in embodiment 1 is described. 
         [0198]    As shown in  FIG. 20(   a ), the width of the ventilation pass  141   g  of the foamed water saving aerator  100  can be adjustable. The configuration of the ventilation pass variable mechanism is not shown in  FIG. 20 . A suitable mechanism that can widen or narrow the ventilation pass  141   g  can be employed. For example, a slide mechanism for sliding a shutter covering a part of the ventilation pass  141   g , or a mechanism for varying the wall forming the edge of the ventilation pass  141   g  can be employed as the ventilation pass variable mechanism. 
         [0199]      FIG. 20(   b ) shows the status of the adjusted ventilation pass  141   g  whose width is narrowed from the state of the ventilation pass  141   g  shown in  FIG. 1 . If the width of the ventilation pass  141   g  become small, the air speed injected from the ventilation pass  141   g  varies according to the area (width) of the ventilation pass  141   g  because the amount of the ventilated air to the inner space  113  is determined by the air pressure decrease of the inner space  113  of the surrounding water flow curtain  112 . As a result, the air speed injected from the adjusted ventilation pass  141   g  shown in  FIG. 20(   b ) to the inner space  113  becomes faster than that injected from the ventilation pass  141  shown in  FIG. 1   
         [0200]    The surface area for contacting the air in the inner space  113  is the same in both the surrounding water flow curtain  112  generated in the air cavity  120  in the foamed water saving aerator  100  shown in  FIG. 1  and the surrounding water flow curtain  112  generated in the air cavity  120  in the foamed water saving aerator  100  shown in  FIG. 20(   b ). Therefore, the amount of the air introduced into the surrounding water flow curtain  112  becomes large according to the speed of the air injected from the inner space  113 . 
         [0201]    As shown above, the width of the ventilation pass  141   g  can be adjustable, and the ventilation pass variable mechanism is employed. The speed of the air injection to the surrounding water flow curtain  112  can be adjustable, and the amount of the air injected to the surrounding water flow curtain  112  can be adjustable. 
       Embodiment 7 
       [0202]    Embodiment 7 shows the foamed water saving aerator configuration, in which there is a gap width variable mechanism for varying the gap width, and the thickness of the surrounding water flow curtain can be adjusted. 
         [0203]      FIG. 21  is a schematic view of the foamed water saving aerator  100   h  comprising a gap width variable mechanism. The gap width variable mechanism can be applied to any of the foamed water saving aerator  100  shown in embodiment 1 to embodiment 6. For example, the gap width variable mechanism applied to foamed water saving aerator shown in embodiment 3 is described. 
         [0204]    As shown in  FIG. 21(   a ), in the foamed water saving aerator  100   h , the part  102  shown in  FIG. 2  can be adjusted upwardly and downwardly by screwing into the part  101 , and the disk  1021  of the part  102  and the upper tubular  1011  of the part  101  can be moved relatively. Any structure can be employed as a gap width variable mechanism that can move the disk  1021  of the part  102  and the upper tubular  1011  of the part  101  relatively. 
         [0205]      FIG. 21(   b ) is a schematic view of the state in which the width of the gap  111   h  becomes large by shifting the disk  1021  of the part  102  shown in  FIG. 2  downward relative to the upper tubular body  1011  of the part  101 . If the width of the gap  111   h  becomes large, the thickness of the water flow of the surrounding water flow curtain  112   h  injected from the surrounding water flow curtain forming portion  110   h  increases. The accelerated water flow speed is in inverse proportion to the cross sectional area of the gap. Therefore, the speed of the surrounding water flow curtain  112   h  flushed from the gap  111   h  shown in  FIG. 21(   b ) to the air cavity  120  become slower than the surrounding water flow curtain  112   b  flushed from the gap  111   b  shown in  FIG. 3  to the air cavity  120 . 
         [0206]    If the width of the gap  111   h  becomes large, the thickness of the water flow of the surrounding water flow curtain  112   h  becomes large, and the speed of the water flow of the surrounding water flow curtain  112   h  becomes slow. As a result, the amount of the air introduced into the surrounding water flow curtain  112   h  from the inner space  113  becomes small, and the air volume ratio of the surrounding water flow curtain  112   h  becomes small because of the decrease of the amount of the introduced air and the increase of the thickness of the water flow. 
         [0207]    If the width of the gap  111   h  becomes small, the thickness of the water flow of the surrounding water flow curtain  112   h  becomes small, and the speed of the water flow of the surrounding water flow curtain  112   h  becomes fast. As a result, the amount of the air introduced into the surrounding water flow curtain  112   h  from the inner space  113  becomes large, and the air volume ratio of the surrounding water flow curtain  112   h  becomes large because of the increase of the amount of the involved air and the decrease of the thickness of the water flow. 
         [0208]    According to the water saving aerator, if the foamed water saving aerator employs the gap width variable mechanism, the adjustment of the thickness and speed of the surrounding water flow curtain can be controlled, and the amount of the air involved in the surrounding water flow curtain can be adjusted. 
         [0209]    While some preferable embodiments of the water saving aerator according to the present invention are described above, it should be understood that various changes are possible, without deviating from the technical scope according to the present invention. Therefore, the technical scope according to the present invention is limited only by the claims attached. 
       INDUSTRIAL APPLICABILITY 
       [0210]    The water saving aerator according to the present invention can be used as the water saving apparatus and the bubble foam water generator. The water saving aerator can be applied to various apparatus not limited for its use. For example, it can be applied to the water tap not only for commercial use but also for special use such as laboratory use, the special water delivery pipe such as the water delivery pipe for eye - washing water tap in a pool facility and the shower head.