Abstract:
An electronically controlled breast pump for generating cyclical suction includes a cumulative vacuum pump and a plurality of switches including at least an expression mode cycle time selection switch, a peak vacuum level selection switch, and a stimulation mode switch. A controller coupled to the cumulative vacuum pump controls the apparatus which optionally further includes a four-layer assembly of the various features, an adjustable safety valve, and/or a pump head with a groove traversing top dead center of the pump head.

Description:
CLAIM FOR PRIORITY 
     This non-provisional application claims the benefit of the filing date of U.S. Provisional Patent Application Ser. No. 61/269,282, of the same title, filed Jun. 22, 2009. The priority of U.S. Provisional Patent Application Ser. No. 61/269,282 is hereby claimed and the disclosure thereof is incorporated into this application by reference. 
    
    
     TECHNICAL FIELD 
     The present invention relates to a breast pump including a vacuum pump and a control system therefore. The system provides a plurality of discrete vacuum level settings and a plurality of discrete cycle time settings and is readily switchable between an expression mode and a stimulation mode. A compact 4-layer construction provides better efficiency and ease of manufacture. 
     BACKGROUND OF THE INVENTION 
     Electric breast pumps are known in the art. There is disclosed in U.S. Pat. No. 7,070,400 to Greter a diaphragm suction pump without pump chamber dead space. In particular, the &#39;400 patent is directed to a diaphragm pump wherein the pump diaphragm is driven by an electric motor crank mechanism by means of a connecting rod and spans a pump chamber provided in a base plate. The pump chamber walls are provided with a conically widening profile and the various parts are configured such that the diaphragm bears substantially tightly against the entire pump chamber wall along the sides and at a top dead center position of the connecting rod will result in a position where there is substantially no dead space. It has been found that this particular arrangement is undesirable since there is no means to break the vacuum between the diaphragm and the cylinder pump head upon reciprocation of the diaphragm, resulting in “vacuum lock”. 
     U.S. Pat. No. 6,547,756 to Greter et al. discloses a breast pump which can be programmed to generate a plurality of different milk expression sequences. In one embodiment of the invention, a motorized pump is provided with a microprocessor controller. 
     Also disclosed in pending applications are various features for breast pumps. In this regard, there is disclosed in United States Patent Application Publication No. 2004/0024351 (U.S. patent application Ser. No. 10/413,463) to Greter et al. a breast pump that generates a let-down or stimulation phase and a milk expression phase. See, also, United States Patent Application Publication No. 2007/0292276 (U.S. patent application Ser. No. 11/662,683) to Stutz et al. entitled “Membrane Pump With Bleed Valve.” The Stutz et al. application discloses a vacuum pump with a bleed valve which opens partially at an initial stage and later opens to a greater extent during a pump cycle. 
     While various features and control schemes have been disclosed in the art, electric breast pumps are typically expensive and relatively difficult to operate. There is provided in accordance with the present invention an easy to use, economical breast pump system which provides superior levels of comfort and adjustability without complex operating modes. 
     SUMMARY OF INVENTION 
     There is provided in accordance with the invention an electronically controlled breast pump for generating cyclical suction comprising (a) a cumulative vacuum pump with a release valve; (b) a plurality of switches including at least an expression mode cycle time selection switch, a peak vacuum level selection switch, and a stimulation mode switch; and (c) a controller coupled to the cumulative vacuum pump including the release valve and at least the expression mode cycle time switch, the peak vacuum level selection switch, and the stimulation mode selection switch. The electronically controlled breast pump is adapted to provide at least three discreet expression mode vacuum cycle time settings, at least five discreet peak vacuum level settings, and at least one discreet stimulation mode vacuum cycle time setting. 
     In one preferred embodiment, an electronically controlled cumulative vacuum breast pump includes a pump head communicating with a suction valve and an exhaust valve as well as a groove traversing top dead center of the pump head. The groove traversing top dead center of the pump head is operative to ameliorate vacuum lock of the diaphragm upon motion thereof. 
     In another preferred embodiment, a four-layer assembly for the electronically controlled breast pump includes: (a) a suction/exhaust manifold plate having a suction line communicating with a release line and an exhaust port isolated from the suction line and release line; (b) a valve membrane plate juxtaposed with the suction/exhaust manifold plate having a suction valve flap communicating with the suction line of the manifold plate and an exhaust flap communicating with the exhaust port of the manifold plate and a release aperture as well as a safety aperture communicating with the release line of the manifold plate; (c) a pump head plate juxtaposed with the valve membrane plate which defines a vacuum chamber as well as the suction aperture communicating with the suction line of the manifold plate, an exhaust aperture communicating with the exhaust port on the manifold plate, a release aperture communicating with the release line of the manifold plate, and a safety aperture communicating with the release line of the manifold plate; and (d) a diaphragm membrane juxtaposed with the pump head plate having a release valve portion, a diaphragm portion, and a safety valve portion. 
     In still yet another aspect of the present invention, there is provided an adjustable safety valve communicating with a vacuum line of a cumulative vacuum breast pump comprising an elastomeric membrane with a venting aperture pre-tensioned against the closure member such that the closure member seals the aperture up to a predetermined vacuum level and wherein the tension between the membrane and the closure member is adjustable by virtue of positioning the closure member. Adjustment of the closure member thus adjusts tension between the membrane and the closure member. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention is described in detail below with reference to the drawings wherein like numerals designate similar parts. In the drawings: 
         FIG. 1  is a view in perspective of a vacuum pump console and a pair of collection bottles constructed in connection with the present invention; 
         FIG. 2  is a diagram illustrating expression phase cycle time settings and pressures as well as stimulation phase vacuum settings; 
         FIG. 3  is a schematic diagram illustrating transitions from an expression phase operation to and from a stimulation phase operation of the present invention; 
         FIG. 4  is a plot of pressure vs. time illustrating a typical expression phase pressure/cycle time profile of the vacuum pump system of the present invention; 
         FIG. 5  is a plot of vacuum pressure vs. time for a typical let-down phase (stimulation phase) operation of the vacuum pump system of the present invention; 
         FIG. 6  is a schematic view, in section, of a vacuum pump unit constructed in accordance with the present invention; 
         FIG. 7  is another schematic view, in section, of the vacuum pump unit of  FIG. 6 ; 
         FIG. 8  is an exploded view of the vacuum pump unit of  FIGS. 6 and 7 ; 
         FIG. 9  is another exploded view of the vacuum pump unit of  FIGS. 6 ,  7 , and  8 ; 
         FIG. 10  is yet another exploded view of the vacuum pump unit of  FIGS. 6-9 ; 
         FIG. 11  is still yet another exploded view of the vacuum pump unit of  FIGS. 6-10 , schematically illustrating air flow; 
         FIG. 12  is a partial schematic view, in section, illustrating the release mechanism of the vacuum pump unit of  FIGS. 6-11 ; 
         FIG. 13  is a schematic partial view, in section, illustrating the safety vent release valve of the vacuum pump unit of  FIGS. 6-11 ; and 
         FIGS. 14A and 14B  are a detail of the vacuum pump unit of  FIGS. 6-11  illustrating the suction/exhaust manifold of the vacuum pump unit. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The invention is described in detail below for purposes of exemplification and illustration only. Modifications to particular embodiments within the spirit and scope of the present invention, set forth in the appended claims, will be readily apparent to those of skill in the art. 
     Referring to  FIG. 1 , there is illustrated a double electric breast pump system  10  which includes a first collection bottle  12  and a second collection bottle  14 . Each of the bottles includes a breast shield  16 ,  18  for receiving a breast. A console  20  houses an electric cumulative vacuum pump  22  as well as a microprocessor (not shown) and a plurality of switches described hereinafter. Console  20  also has a first cavity  24  and a second cavity  26  for receiving bottles  12  and  14 . 
     Also provided on console  20  is an LCD display  28 , an on/off switch  30 , and expression mode cycle time selection switch  32 , a peak vacuum level selection switch  34 , and a stimulation mode switch  36 . 
     The microprocessor controls the cumulative vacuum pump to provide a plurality of operating modes as is seen in  FIG. 2 . 
     It is seen in  FIG. 2  that the breast pump system shown in  FIG. 1  is operated in an expression mode or a stimulation mode. The peak vacuum pressure in the expression mode is selected to be between about 50 and 250 mm of mercury, while the cycle time is selected to be between about 0.5 and 1 cycles per second. In a stimulation mode or “let-down” mode, as is well known in the art, the apparatus  10  is operated at a cycle speed of about 1.85 cycles per second and at a vacuum pressure between about 50 and 150 mm of mercury. The apparatus is switched between the expression mode and the stimulation mode either automatically upon start up or by pressing button  36  to provide higher frequency stimulation. The various control schemes are shown in  FIG. 3 . In  FIG. 3  it is seen that in switching from expression to stimulation mode, the cycle speed is always fixed at 1.85 cycles per second; whereas in switching from stimulation to expression mode, the cycle speed will always be set to a third level of each expression suction level L 1  to L 5  as shown in the diagram. Typical operating parameters for the system are provided below in Tables 1 and 2. 
     
       
         
               
             
               
               
             
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 EXPRESSION PHASE VACUUM LEVEL &amp; CYCLE SPEED SETTINGS TABLE 
               
             
          
           
               
                 Vacuum 
                 Cycle Speed Settings 
               
             
          
           
               
                 Level 
                 C1 
                 C2 
                 C3 
                 C4 
                 C5 
                 C6 
               
             
          
           
               
                 Settings 
                 Cycle/ 
                 Cycle/ 
                 Cycle/ 
                 Cycle/ 
                 Cycle/ 
                 Cycle/ 
                 Cycle/ 
                 Cycle/ 
                 Cycle/ 
                 Cycle/ 
                 Cycle/ 
                 Cycle/ 
               
               
                 (mmHg) 
                 sec 
                 min 
                 sec 
                 min 
                 sec 
                 min 
                 sec 
                 min 
                 sec 
                 min 
                 sec 
                 min 
               
               
                   
               
             
          
           
               
                 L1 
                 50 
                 0.65 
                 39 
                 0.72 
                 43 
                 0.79 
                 47 
                 0.86 
                 52 
                 0.93 
                 56 
                 1.0 
                 60 
               
               
                 L2 
                 78 
                 0.65 
                 39 
                 0.72 
                 43 
                 0.79 
                 47 
                 0.86 
                 52 
                 0.93 
                 56 
                 1.0 
                 60 
               
               
                 L3 
                 107 
                 0.65 
                 39 
                 0.72 
                 43 
                 0.79 
                 47 
                 0.86 
                 52 
                 0.93 
                 56 
                 1.0 
                 60 
               
               
                 L4 
                 136 
                 0.65 
                 39 
                 0.72 
                 43 
                 0.79 
                 47 
                 0.86 
                 52 
                 0.93 
                 56 
                 1.0 
                 60 
               
               
                 L5 
                 164 
                 0.65 
                 39 
                 0.72 
                 43 
                 0.79 
                 47 
                 0.86 
                 52 
                 0.93 
                 56 
                 1.0 
                 60 
               
               
                 L6 
                 192 
                 0.65 
                 39 
                 0.72 
                 43 
                 0.79 
                 47 
                 0.86 
                 52 
                 0.93 
                 56 
                 1.0 
                 60 
               
               
                 L7 
                 221 
                 0.58 
                 35 
                 0.65 
                 39 
                 0.72 
                 43 
                 0.79 
                 47 
                 0.86 
                 52 
                 0.93 
                 56 
               
               
                 L8 
                 250 
                 0.51 
                 31 
                 0.58 
                 35 
                 0.65 
                 39 
                 0.72 
                 43 
                 0.79 
                 47 
                 0.86 
                 52 
               
               
                   
               
             
          
         
       
     
     
       
         
               
             
               
               
               
               
               
             
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                 TABLE 2 
               
             
             
               
                   
               
               
                 STIMULATION PHASE 
               
               
                 VACUUM LEVEL SETTINGS 
               
             
          
           
               
                   
                 Vacuum 
                   
                 Cycle 
                   
               
               
                   
                 Level 
                   
                 speed setting 
               
               
                   
                 Settings 
                   
                 C 
               
             
          
           
               
                   
                 (mmHg) 
                   
                 Cycle/sec 
                 Cycle/min 
               
               
                   
                   
               
             
          
           
               
                   
                 L1 
                 50 
                 1.85 
                 111 
               
               
                   
                 L2 
                 64 
                 1.85 
                 111 
               
               
                   
                 L3 
                 78 
                 1.85 
                 111 
               
               
                   
                 L4 
                 92 
                 1.85 
                 111 
               
               
                   
                 L5 
                 106 
                 1.85 
                 111 
               
               
                   
                 L6 
                 120 
                 1.85 
                 111 
               
               
                   
                 L7 
                 135 
                 1.85 
                 111 
               
               
                   
                 L8 
                 150 
                 1.85 
                 111 
               
               
                   
                   
               
             
          
         
       
     
     A typical suction curve for expression mode is shown in  FIG. 4 . In  FIG. 4  the breast pump system  10  generates a peak vacuum of about 100 mm of mercury at a cycle time of about 0.8 seconds per cycle. As can be seen, a typical curve has a cyclical suction profile which mimics the suction of an infant on a breast. Of course, the simple curve shown in  FIG. 4  is similarly achieved at the other levels shown in Table 1. 
       FIG. 5  is a typical cyclical suction curve for stimulation mode operation of the breast pump apparatus  10 . In  FIG. 5  it is seen that the vacuum is set at a peak vacuum of about 92 mm of mercury and a cycle time at about 1.85 cycles per second. Other pressure settings are likewise selected by operation of switch  34  on system  10 , as is shown above in Table 1. 
     The various features of system  10  are better appreciated by reference to  FIGS. 6-14  which illustrate a cumulative vacuum pump  22  with its various features. 
     Cumulative vacuum pump  22  includes a motor  40 , a connecting rod  42 , a pump diaphragm  44 , as well as a release unit  46 . Also provided is as a safety unit  48 . Pump diaphragm  44  is part of a diaphragm membrane  50  which is juxtaposed with a pump head plate  52 . Also provided are a membrane plate  54  and a suction/exhaust manifold plate  56 . Motor  40  is eccentrically coupled to connecting rod  42 , which in turn is secured to diaphragm  44  with a mounting washer  58  as well as a screw  60 . As the motor turns, the connecting rod drives the diaphragm toward the pump head plate  52  in order to actuate the pump. The connecting rod may also draw the diaphragm away from the pump head or simply allow the diaphragm to return to the position shown in  FIG. 6  by virtue of elastic recovery. The diaphragm is suitably made from any suitable elastomeric material such as acrylic elastomers; butyl rubber; chlorosulfonated polyethylene; ethylene-propylene rubber; fluorinated elastomers; neoprene; nitrile rubber; polybutadiene; polyethers; polyisoprene; polypentenamers; styrene-butadiene rubber; and thermplastic elastomers. See,  Kirk - Othmer Encyclopedia of Chemical Technology,  3 rd  Ed., Vol. 8 pp. 446-640, the disclosure of which is incorporated herein by reference. Other rubbers from which the pump diaphragm may be made include silicone rubber or natural rubber based materials. Suitable silicone rubber materials are described in  Kirk - Othmer Encyclopedia of Chemical Technology,  3 rd  Ed, Vol. 20, pp. 943-53, the disclosure of which is incorporated herein by reference 
     The process generates vacuum due to the configuration and valving of the system. To this end, pump head plate  52  defines a vacuum chamber  62  which is provided with a suction valve aperture  64  as well as an exhaust valve aperture  66 . Between apertures  64  and  66  there is provided a groove  68  across top dead center of pump head  70 . Groove  68  provides dead space at top dead center of pump head  70  in order to ameliorate “vacuum lock” of the diaphragm as it reciprocates and generates vacuum. 
     Suction valve aperture  64  is adjacent a suction valve flap  72  on membrane plate  54 . A suction valve seat  74  is provided on suction/exhaust plate  56  such that the suction valve communicates with a suction line  84 . 
     Exhaust valve aperture  66  is juxtaposed with an exhaust valve flap  78  on membrane plate  54 . The exhaust valve flap has a seat  80  on pump head plate  52 . When diaphragm  44  moves toward and away from the pump head, the valves operate as follows. When diaphragm  44  moves toward pump head  70 , flap  78  will unseat from valve seat  80  and exhaust the exhaust air from chamber  62  to exhaust port  82 . 
     When diaphragm  44  moves away from pump head  70 , suction valve flap  72  unseats from valve seat  74  of suction/exhaust manifold plate  56 , thus opening the aperture. At the same time, exhaust flap  78  will seat on seat  80 , thus sealing the vacuum chamber such that vacuum is applied to a vacuum line  84  of the unit. Thus it is seen that the vacuum chamber communicates with the vacuum line through suction valve aperture  64  and suction valve flap  72  upon motion of the diaphragm away from the pump head; and the vacuum chamber communicates with exhaust port  82  upon motion of the diaphragm toward the cylinder head through exhaust valve aperture  66  and exhaust valve flap  78 , thus generating a vacuum producing cycle. Inasmuch as pump  22  is a cumulative vacuum pump, the various components are typically selected and operated such that a maximum vacuum occurs at roughly 80 revolutions (or strokes) in one preferred construction. 
     The inventive system may thus be operated with a relatively low power motor, i.e., a 5 or 10 watt motor. The power required to drive our pump at maximum load is 5 W, not 10 W; however we are using a larger motor for our application in order to allow for possible future modifications in the system software and hardware. The motor may be battery driven and yet still generate the relatively high levels of vacuum seen in  FIGS. 4 and 5  as well as Tables 1 and 2 above. In this respect, the motor may be driven by wall current or by AA alkaline batteries, for example. 
     It is important in a cumulative vacuum pump to carefully control the vacuum with a release valve in order to optimize performance, i.e., it is desirable that the exhaust stroke of the diaphragm coincides with a release of a cumulative vacuum to complete a vacuum cycle applied to line  84 . That is to say, the vacuum seen by line  84  is that plotted in  FIGS. 4 and 5 , for example. 
     Thus, the vacuum applied to line  84  is largely controlled by release unit  46  which, in turn, is controlled by the microprocessor which is connected to the switches on control console  20 . 
     Release unit  46  includes a solenoid  92  with an actuator  94  which is attached to a release portion  96  of diaphragm membrane  50 . Pump head plate  52  includes a release channel  98  which communicates with a release aperture  100  of membrane plate  54  which in turn communicates with release line groove  90  of suction/exhaust manifold plate  56 . Thus, release channel  98  communicates with vacuum line  84  to release the vacuum therein upon actuation by the microprocessor control unit in console  20 . The number of strokes between venting may be any suitable number, as noted above maximum vacuum of about 250 mm of mercury or so is reached after about 80 vacuum cycles (1 suction cycle). Note that the air flow through release unit  46  may be provided by a plurality of apertures such as apertures  46   a ,  46   b  in diaphragm membrane  50 . 
     Although the release unit is extremely reliable, a safety unit is also provided so that excess vacuum will not be applied to line  84 . To this end, safety unit  48  includes a set screw  102  which communicates with an aperture  104  in diaphragm membrane  50 . Aperture  104  communicates with another aperture  106  in pump head plate  52 . In operation set screw  102  is advanced onto membrane plate  54  such that there is a tension between the screw and the region of the membrane plate at the safety unit. That is to say, screw  102  bears upon membrane  50  at an area close to aperture  104  in membrane  50 . Aperture  104  communicates with aperture  106  which, in turn, communicates with release line groove  90  through a third aperture  108  in membrane plate  54 . Thus, when a predetermined amount of vacuum builds up in line  84 , the vacuum will draw membrane plate  50  away from set screw  102  and allow air to enter the system, thus breaking the vacuum. A predetermined safety level can be set by adjusting screw  102 . That is to say, additional tension will supply a higher release threshold for the safety unit. Thus, if the release unit does not properly vent the system to provide the desired peak pressure, the safety unit will allow air to enter the system at a predetermined vacuum level and insure that a preset peak vacuum level is not exceeded. 
     The various air flow paths are indicated schematically on  FIG. 11  by a plurality of arrows. 
     Thus, summarizing the above, the cumulative vacuum pump of the present invention is operated in connection with two flap valves. The vacuum phase starts when the vacuum diaphragm is advanced all the way to the pump head. The exhaust flap closes the exhaust line and the suction flap opens the vacuum line, and vacuum is realized due to the connection of the vacuum line to the vacuum bottle and the sealing of the system against the breast of a user. Vacuum is generated over a number of cycles before it is released by the release unit. In this way, the desired vacuum level and cycle times are achieved. The release system is controlled by way of the console switches and microprocessor as described above. The inventive pump is the only mobile cumulative vacuum breast pump available which allows a mother to vary the cycle speed within a limited comfort range, at a given set suction vacuum level setting. This actually allows the user to adjust her own comfort level of extracting milk from her breast. As in nature, if examined randomly, each baby has a different suction repetition rate at a given suction strength level. Therefore; since we are providing a pump with natural suction characteristics, it is important that we give the mother a capacity to adjust the suction repetition rate within the set suction power level and this pump does just that. The mother can conveniently fine-tune tune her suction pattern to match the natural suction characteristics of her baby, which is unique to herself and to her baby. Existing cumulative vacuum pumps generally only allow the mother to select the suction power and the control electronics allocates a predetermined suction repetition rate for the selected suction power level, where the mother cannot change or adjust. She is limited to a predetermined cycle rate programmed into the pump memory. The inventive system introduces the ability to adjust the cycle rate at any given suction power level, from L 1  to L 8  as noted above. 
     The air outlet phase starts when the membrane is withdrawn to the top of the stroke, i.e. away from the pump head. The suction flap closes the suction line as the diaphragm moves down and the exhaust flap opens to allow air to escape from the previous pump cycle. Approximately 80 diaphragm movements are required for achieving maximum vacuum level from this product. 
     The release valve can be opened by a linear solenoid according to adjustments or control from the microprocessor. In this way the vacuum line is open to the atmosphere and controlled set air release phase started. By controlling the release times, the desired suction cycles such as those shown in Table 1 and  FIGS. 4 and 5  are completed. The release unit is controlled with a dedicated algorithm in order to save energy and increase the life time of the solenoid by applying variable controlled power to the solenoid windings, depending on the selected suction level settings. The power required in order to release the diaphragm membrane varies according to the opposing vacuum force, which in turn applies a pulling action away from the solenoid plunger, hence the higher the vacuum setting, more pulling force is required to move the diaphragm membrane away from the venting hole and depending on the vacuum level setting, the required pull force, hence the required power to the solenoid varies. Therefore considerable power saving and lifetime extension of the solenoid is provided by applying low power for low level vacuum settings and high power for higher level vacuum settings. 
     The vacuum level is also limited by placing a safety valve communicating with the suction vacuum line. The safety level is adjusted with a screw. Placement of the screw determines the preload on the safety diaphragm, i.e., in the vicinity of the aperture, and thus provides an adjustable, yet pre-determined safety threshhold. When the vacuum level gets above the defined safety level, the force generated by vacuum exceeds the preloaded force. In this situation, the air flow is realized to the suction line and breaks the vacuum. That is to say, the vacuum level decreases because of the air entering the suction line through the safety unit. The channel will close when the balance between pressure force is created and the force created by the preload is achieved. In this way, protection from extreme vacuum levels is always present, even in the event of failure of the release unit. 
     While the invention has been described in detail, modifications within the spirit and scope of the invention will be readily apparent to those of skill in the art. In view of the foregoing discussion, relevant knowledge in the art and references discussed above in connection with the Background and Detailed Description, the disclosures of which are all incorporated herein by reference, further description is deemed unnecessary. In addition, it should be understood that aspects of the invention and portions of various embodiments may be combined or interchanged either in whole or in part. Furthermore, those of ordinary skill in the art will appreciate that the foregoing description is by way of example only, and is not intended to limit the invention.