Abstract:
This invention discloses an airlift pumping mechanism for a fluid container, which is intended to address the problem of decreasing efficiency of the pumping mechanism when the liquid level in the container is low in the prior art. For this purpose, the airlift pumping mechanism comprises an air compressor and a riser tube assembly, wherein the riser tube assembly is located in a fluid container, and the air compressor is in communication with the riser tube assembly for feeding the compressed air to the riser tube assembly so that the same flows upward through the riser tube assembly together with the fluid in the fluid container. The pumping mechanism is characterized by further comprising a sunken cavity downwardly extending from the inner bottom surface of the fluid container, wherein the sunken cavity is located between the air compressor and the riser tube assembly and is in communication with the air compressor and the riser tube assembly. Due to the downward extension of the sunken cavity from the bottom surface of the container, the submergence ratio of the pumping mechanism can be significantly increased, thereby greatly increasing the pumping efficiency of the pumping mechanism at various liquid levels.

Description:
TECHNICAL FIELD 
       [0001]    The present application relates to the pumping mechanism, and more particularly to the improvement in the airlift pumping mechanism of a fluid container such as a brewing machine, etc. 
       BACKGROUND 
       [0002]    An airlift pumping mechanism is a type of pumping apparatus that uses compressed air as the propellant for pumping fluid up a riser tube. The structure involved is simple and requires little maintenance for reliable operation. So that the mechanism has wide applications in fields such as mining, oil &amp; gas exploration, agriculture, and wastewater treatment. 
         [0003]    WO2012/046159A1 discloses a system that uses an airlift pumping mechanism in an apparatus for applications such as brewing beverages. An embodiment is shown in Error! Reference source not found. The apparatus is generally comprised of a container  30 , an air pump  50 , a riser tube  40 , an infuser  70 , a heater  60 , a sensor  62 , and a control unit  82 . The fluid  20  (e.g. water) and ingredients  25  (such as, tea) for the brewing process are placed in the container  30  and infuser  70 , respectively. The pumping action is achieved by first activating the air pump  50  to produce compressed air. The generated air will force the fluid  20  up the riser tube  40  and released over the ingredients  25  in the infuser  70  (in the direction of arrow A 1 ). Once the infuser  70  is filled with the fluid  20 , the fluid  20  then returns to the container  30  to form a circulative brewing process. The heater  60  located at the bottom  36  of the container  30  provides temperature control during the brewing process. The control unit  82  controls the brewing process according to sensed signals from the sensor  62  and reference signal REF 2 . 
         [0004]    However, there are some problems with the airlift pumping mechanism in WO2012/046159A1. Specifically, firstly, the pumping efficiency is very low at low residual water volumes (i.e. low liquid levels). The pumping efficiency of the airlift pumping mechanism is in proportion to the submergence ratio defined as H w /H s , wherein H w  is the liquid level within the riser tube and H s  is the total length of the riser tube. In general, the higher the submergence ratio is, the higher the pumping efficiency will be. In other words, low water levels, as shown in Error! Reference source not found. when compared with  FIG. 1 , would produce low submergence ratios that would lead to low pumping efficiency or even zero water flow. Such flow rate limitations would negatively impact on the brewing results produced by the system. Secondly, the shape of an air collector has a negative effect on the structural configuration. To more effectively collect and stream the compressed air into the riser tube, a fan-shaped air collector may be used at the lower end of the riser tube (see the sector end  41  in Error! Reference source not found.). However, the horizontal spread of the air collector requires certain amount of clearance in space and may interfere with other structural components, thereby limiting options in structural configuration of the system. Furthermore, there is residual fluid remaining inside the air channel. As shown in  FIG. 3 , the compressed air travels along the air channel P 1  and enters the bottom of the container through an opening  51 . A one-way valve  55  is placed between the air channel P 1  and the opening  51  to prevent backflows of the fluid  20  into the air channel. However, a small amount of residual water may get trapped in the small conduit between the opening  51  and the one-way valve  55 . The reason is that even if the container is drained after use, small liquid drops may still remain inside the container and aggregate at the opening. If not completed dried, such residual water may pose a sanitary concern. 
       SUMMARY OF THE APPLICATION 
       [0005]    The present invention aims at solving the above mentioned problems in the prior art. Specifically, the present invention is designed to optimize the structure of the airlift pumping mechanism, so that the pumping efficiency is relative high at various liquid levels, and meanwhile the limitation on the structural construction of the fluid container is eliminated. To this end, the present invention provides an airlift pumping mechanism for a fluid container comprising a novel sunken cavity that extends further downwards from the inner bottom surface of the fluid container so as to considerably increase the submergence ratio and hence the pumping efficiencies at various liquid levels. 
         [0006]    In one aspect of the present invention, an airlift pumping mechanism for a fluid container is provided. The airlift pumping mechanism comprises an air compressor and a riser tube assembly that is located within the fluid container and communicated with the air compressor to feed the compressed air into the riser tube and flow upward through the riser tube along with the fluid in the fluid container. The airlift pumping mechanism is characterized by also comprising a sunken cavity that extends further downwards from the inner bottom surface of the fluid container and is located between and communicated with the air compressor and the riser tube assembly. 
         [0007]    As described in the background of the invention, the submergence ratio is defined as H w /H s , wherein H w  is the liquid level in the riser tube and H s  is the total length of the tube. Owing to the sunken cavity extending further downwards from the inner bottom surface of the fluid container, the numerator H w  and the denominator H s  in the above mentioned representation is increased so that the value of the submergence ratio and therefore the pumping efficiencies of the pumping mechanism at various liquid levels are drastically increased. Especially when there is less fluid remained within the fluid container, that is, when the liquid level is lower, the submergence ratio will be increased more obviously. Compared with the prior art, the above described technical solutions of the invention will be able to obviously increase the pumping efficiency of the airlift pumping mechanism. 
         [0008]    In an optimized embodiment of the above described airlift pumping mechanism, the riser tube assembly includes a riser tube and a bottom baffle connected to the bottom of the riser tube. When the riser tube assembly is in use, the bottom baffle is hermetically inserted into the sunken cavity, so that the sunken cavity is separated into a cavity body and a fluid intake channel, both of which are communicated with each other; the fluid within the fluid container flows through the fluid intake channel into the cavity body of the sunken cavity to mix with the compressed air from the air compressor. 
         [0009]    The above described bottom baffle and sunken cavity can be of any suitable shape, so long as they are able to match with each other and form a hermetical combination. For example, the bottom baffle and/or the sunken cavity can be provided with silicone rubber to form a tight fit between them upon their insertion to each other. Moreover, vertical dimension of the bottom baffle may be less than that of the sunken cavity by way of example, in order to form one or more gaps between them at the moment of their insertion to each other. Fluid travels from the fluid intake channel through the one or more gaps and finally into the cavity body. 
         [0010]    In an optimized embodiment of the above described airlift pumping mechanism, the airlift pumping mechanism also comprises a horizontally-oriented air inlet channel, which is provided between the cavity body of the sunken cavity and the air compressor to feed the compressed air from the air compressor into the cavity body. 
         [0011]    In particular, the air inlet channel is located in the vicinity of the bottom of the cavity body of the sunken cavity and between the cavity body and the air compressor, so as to let the compressed air run from the air compressor into the cavity body. 
         [0012]    In an optimized embodiment of the above described airlift pumping mechanism, the fluid container includes a heater provided on the inner bottom surface of the fluid container, and the riser tube is vertically located at the side of the heater. In a preferred embodiment of the above described airlift pumping mechanism, the heater is a flat heater, and the riser tube is located near the outer edge of the flat heater. 
         [0013]    Take a brewing machine for example. “The riser tube is located near the outer edge of the flat heater” means that the riser tube is located at the side of the flat heater that is closer to the handle side of the brewing machine. Specifically, the riser tube of the pumping mechanism of the invention is able to be placed much closer to the sidewall of the container, since the riser tuber isn&#39;t provided with a fan-shaped air collector at its end, thereby not only opening up more options in arranging other components but also making fluid containers such as brewing machines better looking. 
         [0014]    In an optimized embodiment of the above described airlift pumping mechanism, the riser tube includes a plurality of inner channels. Accordingly, the provision of more channels is able to maximize the pumping effect, without obviously increasing the structural complexity. 
         [0015]    In an optimized embodiment of the above described airlift pumping mechanism, the fluid container also includes an infuser located near the top of the fluid container opposed to the heater, and the infuser is communicated with the top of the riser tube, along which the upward flow finally enter into the infuser under the action of the compressed air. 
         [0016]    In an optimized embodiment of the above described airlift pumping mechanism, the air inlet channel is located at such a position and orientation that the distance between its lower edge and the bottom surface of the sunken cavity is equivalent to the diameter of the air inlet channel or is 3 mm, and that this distance is larger than that between the lower edge of the bottom baffle and the bottom surface of the sunken cavity. Accordingly, when the fluid container is drained after use, it is easy to expel liquid remaining inside the air inlet channel. Moreover, liquid drops remaining inside the sunken cavity would settle at the bottom of the sunken cavity rather than inside the air inlet channel, as a result the hygiene troubles faced by the pumping mechanisms in the prior art are avoided. 
         [0017]    In another aspect of the invention, a fluid container is provided. The fluid container comprises the airlift pumping mechanism described in any one of previous technical solutions. 
         [0018]    In yet another aspect of the invention, a brewing machine is provided. The brewing machine comprises the airlift pumping mechanism described in any one of previous technical solutions. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]      FIG. 1  is a schematic view of the structure of an airlift pumping mechanism in the prior art, wherein the liquid level in the container is high; 
           [0020]      FIG. 2  is a schematic view of the structure of an airlift pumping mechanism in the prior art, wherein the liquid level in the container is low; 
           [0021]      FIG. 3  is an enlarged partial view of the lower part of the riser tube of an airlift pumping mechanism in the prior art; 
           [0022]      FIG. 4  is an illustration of the fluid container according to the present invention, wherein specifically the fluid container is a brewing machine; 
           [0023]      FIG. 5  is a side view of the airlift pumping mechanism according to the invention; 
           [0024]      FIG. 6  is a top view of the airlift pumping mechanism according to the invention; 
           [0025]      FIG. 7  is a top view of the airlift pumping mechanism according to the invention, wherein some components are omitted to show the inner structure more clearly; 
           [0026]      FIG. 8  is a side view of the riser tube assembly of the airlift pumping mechanism according to the invention; 
           [0027]      FIG. 9  is a front view of the riser tube assembly of the airlift pumping mechanism according to the invention; 
           [0028]      FIG. 10  is a bottom view of the riser tube of the airlift pumping mechanism according to the invention; 
           [0029]      FIG. 11  is a partially enlarged side view of the airlift pumping mechanism according to the invention, wherein the related details of the sunken cavity are shown; 
           [0030]      FIG. 12  is a side view of the airlift pumping mechanism according to the invention, wherein the fluid flow path and the air flow path during operation are shown; 
           [0031]      FIG. 13  is a partially enlarged side view of the airlift pumping mechanism according to the invention, wherein the fluid flow path and the air flow path in the sunken cavity during operation are shown; and 
           [0032]      FIG. 14  is a side view corresponding to  FIG. 12 , wherein a variety of dimension parameters related to the pumping efficiency are shown. 
       
    
    
     DETAILED DESCRIPTION 
       [0033]    What has to be explained beforehand is that, technical solutions in the invention will be described below in connection with a brewing machine and an airlift pumping mechanism for the brewing machine. However, as should be readily understood by those skilled in the art, apparently technical solutions in the invention can be applied to other fluid containers such as coffee maker and other fields for example oil and gas exploration and wastewater treatment, etc, without altering the principles of the present disclosure. These changes don&#39;t depart from the principles of the invention and don&#39;t need any creative work, and therefore they are also intended to be within the scope of protection disclosed by the invention. 
         [0034]    Specifically, the invention provides an airlift pumping mechanism for a brewing machine. The airlift pumping mechanism comprises an air compressor and a riser tube assembly which is located within the brewing machine and communicated with the air compressor to let the compressed air enter into the riser tube and flow upward through the riser tube assembly along with the fluid in the brewing machine. The airlift pumping mechanism is characterized by also comprising a sunken cavity that extends further downwards from the inner bottom surface of the brewing machine and is located between and communicated with the air compressor and the riser tube assembly. Accordingly, the numerator H w  and the denominator H s  in the above mentioned representation is increased simultaneously so that the value of the submergence ratio and therefore the pumping efficiency of the pumping mechanism at various liquid levels are drastically increased, since the airlift pumping mechanism of the invention comprises a sunken cavity extending further downwards from the inner bottom surface of the brewing machine. Especially when there is less fluid remained within the brewing machine, that is, when the liquid level is lower, the submergence ratio will be increased more obviously. Therefore, compared with the prior art, the above described technical solutions of the invention will be able to increase the pumping efficiency of the airlift pumping mechanism. 
         [0035]    The new pumping mechanism of the invention and its operational principles are described in detail below with reference to the accompanying figures. Referring first to  FIG. 4 , it illustrates a schematic view of the brewing machine  1  according to the invention. The brewing machine  1  includes a container body  11 , an infuser  14 , a riser tube  15  and a heater  16 . In addition, the brewing machine  1  also includes a base  12 , a spout  10 , and an opening  13  located on the container body  11 , through which fluid can flow into the spout  10 . The skilled person will appreciate that the brewing machine  1  of the invention also includes many other components other than above described components, but there is no need to describe those components, for the technical solutions in the invention and their operations don&#39;t involve them. 
         [0036]      FIG. 5  shows a side view of the airlift pumping mechanism according to the invention. This airlift pumping mechanism is located in the brewing machine  1  shown in  FIG. 1 , and many unrelated components are omitted in  FIG. 5  in order to more clearly reveal the core structures of the invention. The heater  16  is located at the bottom of the container. A sunken cavity  18  located at the right side of the heater  16  (according to the position and direction shown in  FIG. 5 ) extends downwards from the bottom of the container body  11 . A horizontally-oriented air inlet channel  19  is located slightly above the inner bottom surface of the sunken cavity  18  and its one end is connected with the air compressor (not shown in figures). As a non-limiting example, the distance between the bottom surface of the sunken cavity  18  and the lower edge of the air inlet channel  19  is 3 mm or is equivalent to the diameter of the air inlet channel  19 . The bottom baffle  17  connected with the bottom end of the riser tube  15  is inserted into the sunken cavity  18 . The top end of the riser tube  15  communicates with the infuser  14 . Although as shown in  FIG. 5  the sunken cavity  18  is downwardly wedge-shaped in cross-section, which however is merely exemplary in nature, those skilled in the art may chose as appropriate other shapes without departing from the principles of the invention. 
         [0037]      FIG. 6  is a top view of the airlift pumping mechanism according to the invention corresponding to  FIG. 5  with the container body  11  and the infuser  14  removed for clarity. As shown in  FIG. 6 , when the bottom baffle  17  is inserted into the sunken cavity  18 , an independent fluid intake channel  181  is separated within the sunken cavity  18  by the bottom baffle  17 . In use, water in the container body  11  flows through the fluid intake channel  181 , via a gap  182  (best shown in  FIG. 11 ), and into the main body of the sunken cavity  18  in which the water mixes with the compressed air from the air inlet channel  19 . Furthermore, as shown in  FIG. 6 , in addition to the fluid intake channel  181 , in the insertion state, the riser tube  15  and the bottom baffle  17  completely cover the main body of the sunken cavity  18 . 
         [0038]      FIG. 7  is another top view of the airlift pumping mechanism according to the invention corresponding to  FIG. 6 , wherein the riser tube  15  and the bottom baffle  17  are omitted to show the sunken cavity  18  and the air inlet channel  19  more clearly. 
         [0039]      FIG. 8  is a side view of the airlift pumping mechanism according to the invention. The riser tube assembly includes a riser tube  15  and a bottom baffle  17 , and the riser tube assembly is designed to be detachable from the brewing machine  1  for easy handling and cleaning. In actual use, both the riser tube  15  and the bottom baffle  17  are fastened together as a single component by means of such as welding, clipping, etc.  FIG. 9  is an elevation view of the riser tube of the airlift pumping mechanism according to the invention. Similar to the sunken cavity  18 , although the bottom baffle  17  is wedge-shaped in cross section in  FIGS. 8 and 9 , which is merely exemplary in nature, those skilled in the art may choose other appropriate shapes without departing from the principles of the invention, as long as the bottom baffle  17  can be inserted into the sunken cavity  18  hermetically and divides the sunken cavity  18  into a fluid intake channel  181  and a main body, both parts communicate with one another. 
         [0040]      FIG. 10  is a bottom view of the airlift pumping mechanism according to the invention. As shown, the riser tube  15  can include one or more internal channels. In this embodiment, the riser tube  15  is illustratively shown to include four internal channels in order to get a better pumping effect. 
         [0041]      FIG. 11  is a partially enlarged side view of the airlift pumping mechanism according to the invention, wherein the related details around the sunken cavity  18  are shown. The bottom baffle  17  is shaped in such a way that when inserted into the sunken cavity  18 , both parts will form a tight fit along the sidewalls of the sunken cavity  18  while keeping the sunken cavity  18  and the container body  11  in communication with each other as well. The tight fit between the bottom baffle  17  and the sunken cavity  18  is achieved by seals and coatings such as silicon rubber. The bottom baffle  17  vertically extends downwards and forms a gap  182  at the bottom of the sunken cavity  18 . The gap  182  communicates the fluid intake channel  181  and the main body of the sunken cavity  18 , and the fluid intake channel  181  communicates with the inside of the container body  11 . Thus, water or other fluid from the container body  11  can pass through the fluid intake channel  181 , via the gap  182 , and into the main body of the sunken cavity  18 . It should be noted at this point that the height of the gap  182  should be slightly less than the distance between the lower edge of the air inlet channel  19  and the bottom of the sunken cavity  18 . In other words, taking the bottom/bottom surface of the sunken cavity  18  as the benchmark, the lower edge of the air inlet channel  19  should be higher than the lower edge of the bottom baffle  17 . Otherwise, the compressed air from the air inlet channel  19  will somewhat obstruct the water flowing via the gap  182  into the main body of the sunken cavity  18 . Also residual liquid drops will be able to flow into the air inlet channel  19  after use, in which all of these are extremely undesirable. Of course, the difference in their heights shall not be too large, or else it will impact the lifting effect of the compressed air on the flowing water and therefore reduce the pumping efficiency. 
         [0042]    Because a fan-shaped air collector is not provided in the present invention, the riser tube  15  is able to be placed closer to the sidewall of the container body  11 , thereby opening up more options in general structural configuration, such as larger diameter and internal volume for the infuser  14 . Also, as particularly shown in  FIGS. 6-9 , the sunken cavity  18  is able to be made narrower to reduce its internal volume and increase the pumping efficiency, owing to the flat plate structure of the bottom baffle  17  inserted in the sunken cavity  18 . 
         [0043]      FIG. 12  is a side view of the airlift pumping mechanism according to the invention, wherein the water flow path and air flow path during operation are shown. In  FIG. 12 , the water flow path is indicated by white arrows, the air flow path is indicated by black arrows, and the liquid level is indicated by a broken line.  FIG. 13  is a partially enlarged side view of the airlift pumping mechanism according to the invention, wherein the water flow path and air flow path in the sunken cavity during operation are shown. 
         [0044]    When the air from the horizontally-oriented air inlet channel  19  is injected into the sunken cavity  18 , it mixes with the fluid in the cavity and therefore the buoyancy force of the mixture increases, thereby creating an upward lifting force. As the bottom baffle  17  maintains a tight fit with the sidewalls of the sunken cavity  18 , the liquid-air mixture would be pushed up the riser tube  15  through its internal channels. The elevated water would exit the riser tube  15  to enter into the infuser  14 , and would eventually return to the container body  11  with the increase of the liquid level in the infuser  14 . Water from the container body  11  will flow down the fluid intake channel  181  of the sunken cavity and pass through the gap  182  to fill the sunken cavity  18 . 
         [0045]    As previously discussed, the pumping efficiency of the airlift pumping mechanism depends on the submergence ratio. As for the pumping mechanism of the invention, the dimensions of the sunken cavity  18  need to be considered to calculate the submergence ratio.  FIG. 14  is a side view corresponding to  FIG. 12 , wherein various dimension parameters related to the pumping efficiency are shown. Specifically,  FIG. 14  shows a variety of dimensions used to calculate the submergence ratio, and Table 1 shows the calculation results derived from practical example dimensions. It can be seen from Table 1 that with the addition of the sunken cavity  18 , the submergence ratio of all listed liquid levels have increased, especially those at low liquid levels when considering the absolute percentage increase. That is to say, the lower the liquid levels are, the more the submergence ratio increases; and the deeper the sunken cavity  18  is, the more the submergence ratio increases. Of course, it should be readily understood that, the overall structural design should be taken into account when choosing the depth of the sunken cavity  18 , as such the depth can&#39;t be increased infinitely just for the sole purpose of achieving a better pumping efficiency. 
         [0000]    
       
         
               
               
               
               
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                 Length 
                   
                   
                   
                   
                   
               
               
                 of the 
                   
                 Depth 
                   
                 New 
               
               
                 riser 
                 Liquid 
                 of the 
                 Original 
                 submergence 
               
               
                 tube 
                 level 
                 cavity 
                 submergence 
                 ratio 
                 Difference 
               
               
                 (mm) 
                 (mm) 
                 (mm) 
                 ratio (mm) 
                 e = (b + c)/(a + c) 
                 % e-d 
               
               
                   
               
             
             
               
                 140 
                 60 
                 40 
                 42.86% 
                 55.56% 
                 12.70% 
               
               
                 140 
                 50 
                 40 
                 35.71% 
                 50.00% 
                 14.29% 
               
               
                 140 
                 40 
                 40 
                 28.57% 
                 44.44% 
                 15.87% 
               
               
                 140 
                 30 
                 40 
                 21.43% 
                 38.89% 
                 17.46% 
               
               
                 140 
                 20 
                 40 
                 14.29% 
                 33.33% 
                 19.05% 
               
               
                   
               
             
          
         
       
     
         [0046]    The horizontally-oriented air inlet channel  19  is located at a small distance above the bottom surface of the sunken cavity  18 . Therefore, when the brewing machine  1  is drained after use by pouring, it is easy to expel liquid remaining inside the air inlet channel  19 . Also, liquid drops remaining inside the sunken cavity  18  would settle at the bottom of the sunken cavity  18  rather than inside the air inlet channel  19 , as a result the hygiene problems faced by the pumping mechanisms in the prior art are avoided. 
         [0047]    So far, though the technical solutions of the present invention has been described in connection with the preferred embodiments shown in the accompanying figures, it should be readily appreciated that the protection scope of the invention is obviously not limited to these specific embodiments. Without departing from the principles of the invention, equivalent alterations to or substitutions of related technical features can be made by those skilled in the art, these altered or substituted technical solutions are intended to be within the scope of the invention.