Abstract:
A breast pump system includes a vacuum break backflow preventer for preventing breast milk from accidentally backflowing into a suction tube leading to a vacuum pump. The backflow preventer is a vacuum passageway with two spaced apart suction openings. The two openings convey air to cyclically pressurize and depressurize a small milk charging chamber. If milk accidentally covers one of the openings, air at the other opening minimizes the pressure differential that might otherwise draw the milk deep into the suction tube and toward the vacuum pump. For ease of cleaning and sanitizing, the system avoids or minimizes the use of baffles, permanently enclosed passageways, moving parts, and tight inside corners. Some passageways can be split open for access during cleaning. To make the breast milk collection device less protruding under a brassier, the vacuum passageway curves around the side of a nipple receptacle rather than in front of it.

Description:
FIELD OF THE DISCLOSURE 
       [0001]    The subject invention generally pertains to human breast milk collection systems and more specifically to means for inhibiting milk from backflowing through a suction tube leading to a vacuum pump. 
       BACKGROUND 
       [0002]    Breast pump systems are used for collecting breast milk expressed from a lactating woman. Some breast pump systems have a milk collection device with a funnel that fittingly receives the woman&#39;s breast. In many cases, a vacuum pump provides cyclical periods of positive and negative pressure to the milk collection device. During periods of negative pressure (subatmospheric pressure), vacuum delivered to the device withdraws a small discrete volume of milk from the breast and conveys that charge of milk to a small charging chamber. During each period of positive pressure, lightly pressurized air relaxes the breast momentarily and at the same time forces the charge of milk from the charging chamber to a larger milk storage chamber. The cycle repeats until the storage chamber is full or the woman is finished “pumping.” 
         [0003]    Some breast pump systems have a milk collection device that is worn within the cup of a common brassiere. Examples of such systems are disclosed in U.S. Pat. Nos. 7,559,915; 8,118,772; and 8,702,646; all of which are incorporated herein by reference 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0004]      FIG. 1  is a cross-sectional side view of an example milk collection device constructed in accordance with the teachings disclosed herein. 
           [0005]      FIG. 2  is a combination schematic diagram and cross-sectional side view similar to  FIG. 1  but showing the milk collection device as part of an example breast pump system. 
           [0006]      FIG. 3  is a view similar to  FIG. 2  but showing the system during a positive pressure period rather than a suction pressure period. 
           [0007]      FIG. 4  is a cross-sectional side view of the milk collection device shown in  FIGS. 1-3 , but showing the device fully tipped over and pointed down. 
           [0008]      FIG. 5  is a cross-sectional view of the milk collection device shown in  FIG. 1  but showing the device in a disassembled cleaning state. 
           [0009]      FIG. 6  is a cross-sectional view similar to  FIG. 1  but with the outer shell omitted. 
           [0010]      FIG. 7  is a cross-sectional view showing a portion of  FIG. 6 . 
           [0011]      FIG. 8  is a cross-sectional view taken along line  8 - 8  of  FIG. 7 . 
           [0012]      FIG. 9  is a cross-sectional view showing a portion of  FIG. 6 . 
           [0013]      FIG. 10  is a cross-sectional view taken along line  10 - 10  of  FIG. 9 . 
           [0014]      FIG. 11  is a cross-sectional view showing a portion of  FIG. 6 . 
           [0015]      FIG. 12  is a cross-sectional view taken along line  12 - 12  of  FIG. 11 . 
           [0016]      FIG. 13  is a cross-sectional view showing a portion of  FIG. 6 . 
           [0017]      FIG. 14  is a cross-sectional view taken along line  14 - 14  of  FIG. 13 . 
           [0018]      FIG. 15  is a cross-sectional view similar to  FIG. 10  but showing an airflow pattern during a negative pressure period (first period). 
           [0019]      FIG. 16  is a cross-sectional view similar to  FIG. 15  but showing an airflow pattern during a positive pressure period (second period). 
           [0020]      FIGS. 17 and 18  are illustrations demonstrating an example “vacuum break” concept. 
           [0021]      FIG. 19  is an illustration demonstrating another example “vacuum break” concept. 
           [0022]      FIG. 20  is a cross-sectional view similar to  FIG. 1  but showing another example milk collection device constructed in accordance with the teachings disclosed herein. 
           [0023]      FIG. 21  is a cross-sectional view similar to  FIG. 1  but showing another example milk collection device constructed in accordance with the teachings disclosed herein. 
           [0024]      FIG. 22  is a cross-sectional view similar to  FIG. 1  but showing of another example milk collection device constructed in accordance with the teachings disclosed herein. 
       
    
    
     DETAILED DESCRIPTION 
       [0025]      FIGS. 1-16  show various views of an example breast pump system  10  that includes a milk collection device  12  with means for preventing milk  14  from backflowing to a vacuum pump  16 .  FIGS. 17-19  illustrate the underlying operating principle of vacuum breakers. And  FIGS. 21-22  show variations of the system design. The general design isolates a subatmospheric air flow path  102  ( FIG. 10 ) from a milk flow path  20  ( FIG. 9 ) even if milk collection device  12  it tipped completely over ( FIG. 4 ). The vacuum breaker concept keeps fluids separated without using conventional baffles, which inherently have crevices that can be difficult to clean. 
         [0026]    As an overview of the breast pump system&#39;s general construction, milk collection device  12  comprises four main parts: a funnel-shaped breast receiver  22 , a domed outer shell  24 , a fluid exchanger  26 , and a unidirectional valve  28  (e.g., a check valve, a duckbill check valve, a reed valve, a ball check valve, a diaphragm check valve, a swing check valve, etc.).  FIG. 1  shows these for main parts in an assembled operating state with the parts being positioned as a unit in a predetermined orientation, and  FIG. 5  shows them in a disassembled cleaning state. Breast receiver  22  itself comprises a breast guide  30  and a nipple receptacle  32 . Breast guide  30  is generally conical for fittingly receiving a breast  34  of a lactating woman  36 , and nipple receptacle  32  is tubular and defines a nipple chamber  36  for receiving a nipple  38  of breast  34 . 
         [0027]    In some examples, outer shell  24  removably connects to a flange  40  of breast receiver  22  to define a milk storage chamber  42  between outer shell  24  and breast receiver  22 . Fluid exchanger  26  is coupled to breast receiver  22  to provide means for strategically directing milk  14  and air  44  within milk collection device  12 . Valve  28  establishes a milk charging chamber  46  between nipple receptacle  36  and storage chamber  42 . In some examples, charging chamber  46  is cycled between positive and negative pressure to draw discrete quantities of expressed milk from nipple receptacle  36 . During periods of positive pressure, charging chamber  46  discharges each discrete quantity or charge through valve  28  to storage chamber  42 . 
         [0028]    To provide charging chamber  46  with air  44  cyclically at subatmospheric pressure and positive or atmospheric pressure, a suction tube  48  couples milk collection device  12  to vacuum pump  16 . The term, “vacuum pump,” refers to any device that provides subatmospheric pressure continuously, cyclically, or at least momentarily. Vacuum pump  16  is schematically illustrated to represent all types of vacuum pumps, examples of which include, but are not limited to, a diaphragm pump, a bellows pump, a piston pump, a reciprocating pump, a peristaltic pump, a positive displacement pump, a gear pump, a lobed rotor pump, a screw compressor, a scroll compressor, and a rotary vane pump. 
         [0029]    The breast pump system&#39;s structure and operation can be further understood with additional definitions and explanations of some detailed features of the system. Nipple receptacle  36  has an inner curved wall surface  50 , an outer curved wall surface  52 , a proximate end  54  and a distal end  56 . The nipple receptacle&#39;s tubular shape defines a longitudinal centerline  58  and nipple chamber  30 . A minimum radial distance  60  exists between longitudinal centerline  58  and inner curved wall surface  50 , wherein the minimum radial distance is measured perpendicular to centerline  58 . Nipple receptacle  36  extends longitudinally in a forward direction  62  (parallel to centerline  58 ) from proximate end  54  to distal end  56 . In some examples, nipple chamber  36  extends farther forward than distal end  56  of nipple receptacle  32 ; however, any part of nipple receptacle  32  that happens to extend farther forward than nipple chamber  36  is considered an extension beyond distal end  56  and thus is not considered the receptacle&#39;s distal end  56  itself. In some examples, the most forward point of nipple chamber  36  is at a domed concave surface  64  on fluid exchanger  26 . Surface  64  being domed rather than flat makes fluid exchanger  26  easier to clean after fluid exchanger  26  is separated from breast receiver  22 . 
         [0030]    When breast receiver  22  and valve  28  are attached to fluid exchanger  26 , the resulting assembly produces various fluid passages, chambers and sealing interfaces. Upon disassembly, the passages, chambers and sealing interfaces become more open for easier cleaning and sanitizing. Examples of such passages, chambers and sealing interfaces include charging chamber  46 , nipple chamber  36 , a milk passage  66  for conveying milk  14  from nipple chamber  36  to charging chamber  46 , a valve outlet  68  that periodically discharges discrete volumes of milk  14  to storage chamber  42 , an air duct  70  that connects suction tube  48  in fluid communication with charging chamber  46 , a primary sealing interface  72 , and a secondary sealing interface  74 . 
         [0031]    In some examples, system  10  operates in an alternating manner of suction periods and pressurized periods. During suction periods, as shown in  FIGS. 2 and 15 , vacuum pump  16  applies suction or air at subatmospheric pressure to a remote end  76  of suction tube  48 . At least some of the vacuum reaches nipple chamber  36  to draw milk expressed from nipple  38 . The expressed milk  14  flows from nipple chamber  36 , flows through milk passage  66 , and collects at the bottom of charging chamber  46 . The negative air pressure produced by vacuum pump  16  creates a first current of air  78  ( FIG. 15 ) that effectively moves from nipple chamber  36  and effectively flows in series through milk passage  66 , through charging chamber  46 , through air duct  70  ( FIGS. 9 ,  10 ,  15  and  16 ), through suction tube  48 , and to vacuum pump  16 . The terms, “effectively moves” and “effectively flows” means that there is some air movement from an upstream point toward a downstream point, but the air at the upstream point will not necessarily reach the downstream point, due to the travel distance and/or other flow constraints. 
         [0032]    During pressurized periods, as shown in  FIGS. 3 and 16 , vacuum pump  16  applies positive air pressure to suction tube  48 . The positive pressure creates a second current of air  80  that effectively flows in series through suction tube  48 , through air duct  70 , through milk passage  66 , and into nipple chamber  36 . The air pressure in charging chamber  46  forces milk  14  (collected during the previous suction period) from charging chamber  46 , down through valve  28 , and into storage chamber  42 . The air pressure in nipple chamber  36  allows breast  34  to relax prior to the next suction period. 
         [0033]    The alternating cycle of suction and pressure is repeated for as long as desired or until storage chamber  42  is filled to some predetermined capacity. Upon completion of the pumping process, any suitable means can be used for transferring collected milk from storage chamber  42  to a bottle or to some other convenient storage container. One example method for transferring milk  14  from storage chamber  42  is to pull suction tube  48  out from within an opening  82  ( FIG. 5 ) between breast receiver  22  and outer shell  24 , and then pour collected milk  14  out through opening  82 . Another method is to turn milk collection device  12  over (e.g.,  FIG. 4 ), remove breast receiver  22  from outer shell  24 , and simply pour milk  14  out from shell  24 . 
         [0034]    Although  FIG. 4  is referred to illustrate means for emptying milk  14  collected in storage chamber  42 , the primary purpose of  FIG. 4  is to show how well device  12  tolerates a completely tipped-over condition while still preventing milk  14  from backflowing into suction tube  48 . Device  12  has three features that prevent milk backflow. One, in the tipped-over position, air duct  70  remains elevated above milk passage  66 . Two, a circumferential seal  74  ( FIG. 12 ) exists between air duct  70  and milk  14  in nipple chamber  36 . Three, air duct  70  connects to charging chamber  46  at two spaced apart openings  86  and  88  (see  FIG. 15  and the explanation referencing  FIGS. 17 ,  18  and  19 ) 
         [0035]    Preventing milk  14  from entering suction tube  48  is important for several reasons. Milk droplets or even a milk film trapped inside a narrow suction tube can be very difficult to thoroughly clean and sanitize. If left unclean, the trapped milk might contaminate future milk collections. Also, if milk in suction tube  48  migrates into vacuum pump  16 , the milk can be even more difficult to remove and can possibly damage or destroy pump  16 . Tolerating such unsanitized conditions is generally unheard of in the fields of medicine and food processing. 
         [0036]      FIG. 6  serves as somewhat of an index drawing for a subsequent series of cross-sectional views. The views in the series are shown in sets of two and are identified as  FIGS. 7-8 ,  FIGS. 9-10 ,  FIGS. 11-12 , and  FIGS. 13-14 .  FIGS. 7-8  show primary sealing interface  72  between an outer diameter of breast receiver  22  and an inner diameter of fluid exchanger  26 . Primary sealing interface  72  is a relatively tight seal that extends 360 degrees circumferentially around centerline  58  to isolate localized pressure or vacuum within charging chamber  46  while the surrounding storage chamber  42  is at atmospheric pressure. In some examples, to ensure a positive seal, interface  72  tapers at 3-degrees in a lengthwise direction with reference to centerline  58 . 
         [0037]      FIGS. 9-10  show one example of air duct  70  connecting vacuum tube  48  in fluid communication with charging chamber  46 . In this example, air duct  70  comprises a supply port  84  at a connection end  90  of suction tube  48 , a first opening  86  at charging chamber  46 , and a second opening  88  at charging chamber  46 . To connect tube  48  to supply port  84 , connection end  90  of suction tube  48  press-fits into a tapered bore  92  of fluid exchanger  26 . A fork  94  (e.g., one path leading to two) in air duct  70  connects supply port  84  in fluid communication with openings  86  and  88 . Features  84 ,  86  and  88  of  FIG. 10  correspond respectively to points  84 ′,  86 ′ and  88 ′ of  FIG. 18 . Features  84 ,  86  and  88  of  FIG. 10  also correspond respectively to points  84 ″,  86 ″ and  88 ″ of  FIG. 19 . 
         [0038]    To apply the “vacuum break” concept illustrated in  FIGS. 17 and 18 , fork  94  straddles nipple receptacle  36  so that openings  86  and  88  are spaced apart in a lateral direction  96  with the nipple receptacle longitudinal centerline  58  being laterally interposed between openings  86  and  88  (dimensions  98  and  100 ). In some examples, nipple receptacle  36  is flanked by openings  86  and  88 , which means that the nipple&#39;s longitudinal centerline  58  is laterally between openings  86  and  88 , as shown in  FIG. 10 . The spaced-apart distance and elevation of openings  86  and  88  can be increased by increasing the diameter of a flange  99  to which valve  28  is attached. 
         [0039]    Still referring to  FIG. 10 , some examples of air duct  70  define a flow path  102  from supply port  84  to first opening  86 , wherein a curved section of flow path  102  extends circumferentially an angular distance  104  of at least thirty degrees to avoid having to create an alternate flow path in front of or through nipple chamber  36 . In some examples, at least one section  106  of flow path  102  lies within a radial gap  108  between fluid exchanger  26  and the nipple receptacle&#39;s outer curved wall surface  52 . Upon disassembling device  12  to its disassembled cleaning state ( FIG. 5 ), section  106  of flow path  102  is split apart, which makes flow path  102  and air duct  70  much more accessible for cleaning. 
         [0040]      FIGS. 11 and 12  show secondary sealing interface  74  radially between fluid exchanger  26  and the nipple receptacle&#39;s outer curved wall surface  52 . Secondary sealing interface  74  provides a barrier that prevents milk  14  from flowing directly from nipple chamber  36  to air duct  70 .  FIG. 11  shows air duct  70  being between primary sealing interface  72  and secondary sealing interface  74 . 
         [0041]    Primary sealing interface  72  is the more critical seal of the two because primary sealing interface  72  is subjected to an appreciable pressure differential between supply port  84  and storage chamber  42 . Secondary sealing interface  74 , however, is not as critical because the pressure differential between supply port  84  and nipple chamber  36  is nearly zero. Consequently, in some examples, primary sealing interface  72  is made to be a tighter seal than secondary sealing interface  74 . In other words, when breast receiver  22  is snugly inserted into fluid exchanger  26 , the radial forces at primary sealing interface  72  is greater than that at secondary sealing interface  74 . 
         [0042]    It can be important to have primary sealing interface  72  be the dominant seal because when breast receiver  22  is inserted into fluid exchanger  26 , something has to “bottom out” first to stop the relative insertion movement of breast receiver  22  into fluid exchanger  26 . If secondary sealing surface  74  or distal end  56  abutting domed surface  64  were to be the first parts to bottom out, that might leave some radial clearance or leak path at primary sealing interface  72 . Intentionally making primary sealing interface  72  be the first to bottom out, loosens the manufacturing tolerances at other near bottom-out locations, thus increasing assembly reliability, reducing tooling costs, and simplifying manufacturing. 
         [0043]      FIGS. 13 and 14  show milk passage  66  between charging chamber  46  and nipple chamber  36 .  FIGS. 14 and 5  show how an irregular shaped upper flange  110  of valve  28  serves as a means for “clocking” or rotationally aligning valve  28  to fluid exchanger  26 . Such alignment can be important to avoid interference between a lower end  112  of valve  28  and outer shell  24 . For instance, if valve  28  were rotated ninety degrees (about a vertical axis  114 ) from the position shown in  FIG. 1 , the valve&#39;s lower end  112  might press up against outer shell  24 , whereby outer shell  24  might hold valve  28  open and prevent it from closing. 
         [0044]      FIGS. 15 and 16  illustrate an example breast pump method operating during a first suction period ( FIGS. 2 and 15 ) and a second pressure period ( FIGS. 3 and 16 ).  FIG. 15  shows during the first period, directing first current of air  78  in a first curved upward direction circumferentially across a first outer convex wall surface  116  of nipple receptacle  32 .  FIG. 15  also shows during the first period, directing a third current of air  118  in a second curved upward direction circumferentially across the nipple receptacle&#39;s first outer convex wall surface  116 .  FIG. 16  shows during the second period, directing second current of air  80  in a first curved downward direction circumferentially across the nipple receptacle&#39;s first outer curved wall surface  116 .  FIG. 16  also shows during the second period, directing a fourth current of air  120  in a second curved downward direction circumferentially across the nipple receptacle&#39;s first outer curved wall surface  116 , wherein nipple receptacle  32  is interposed between first current of air  78  and third current of air  118  during the first period, and nipple receptacle  32  is interposed between second current of air  80  and fourth current of air  120  during the second period. 
         [0045]      FIGS. 17 and 18  illustrates the concept of a vacuum breaker as a means for preventing a liquid  122  from backflowing up to a suction source  124 . Liquid  122  only reaches suction source  124  when both openings  86 ′ and  88 ′ are submerged in liquid  122 , as shown in  FIG. 17 . If only one opening  86 ′ is submerged and the other opening  88 ′ is exposed to air  44 , as shown in  FIG. 18 , air  44  readily supplies the volume drawn in by suction source  124 . Through a given opening, air can flow about thirty times easier than water. Consequently, only a slight pressure differential is needed for air  44  to rush through opening  88 ′ to suction source  124 . That slight pressure differential creates only a slight pressure head  126  that is unable to lift liquid  122  from opening  86 ′ to suction source  124 . 
         [0046]      FIG. 19  provides another example of illustrating a vacuum breaker concept. This example involves the use of a residential water line  128 , an outdoor faucet  130 , a simplified vacuum breaker  132 , and a garden hose  134  partially submerged in a bucket  136  of contaminated water  138 . In this example, if unusual adverse conditions create a vacuum in water line  128 , clean outdoor air  44  rather than contaminated water  138  will be drawn into water line  128 . 
         [0047]      FIGS. 20 ,  21  and  22  show various design modifications.  FIG. 20  shows an altered milk passage  66 ′ created by a beveled edge  140  at the end of a nipple receptacle  32 ′.  FIG. 21  shows an altered milk passage  66 ″ created by a notched edge  142  at the end of a nipple receptacle  32 ″.  FIG. 22  shows that a stubbier fluid exchanger  26 ′ and a less protruding outer shell  24 ′ can be used when air duct  4  curves around the sides of the nipple receptacle rather than in front of it. The stubbier fluid exchanger  26 ′ also reduces the effective volume of charging chamber  46 , which can be beneficial when using certain low displacement vacuum pumps. 
         [0048]    For further clarification, the term, “suction tube” refers to any conduit having a tubular wall of sufficient thickness, stiffness, and/or strength to convey air at subatmospheric pressure. In some examples, suction tube  48  is more flexible than outer shell  24 , breast receiver  22 , and/or fluid exchanger  26 . Such tube flexibility makes tube  48  easier to use and fit to fluid exchanger  26 . The term, “coupled to” refers to two members being connected either directly without an intermediate connecting piece or being connected indirectly via an intermediate connecting piece between the two members. The term, “coupled to” encompasses permanent connections (e.g., bonded, welded, etc.), seamless connections (e.g., the two members are of a unitary piece), and separable connections. The term, “opening” of a fluid pathway refers to a cross-sectional area through which fluid is directed to flow in a direction generally perpendicular to the area as guided by the fluid pathway. The term, “radial gap” refers to clearance as measured in a direction perpendicular to longitudinal centerline  58 . The terms, “negative pressure,” “subatmospheric pressure,” and “vacuum” all refer to a pressure that is less than atmospheric pressure. The term, “positive pressure,” refers to a pressure that is greater than atmospheric pressure. Storage chamber  42  is not necessarily for long term storage but rather for collecting and temporarily storing milk  14  as the lactating woman is expressing milk. In some examples, milk collection device  12  includes a slot-and-key  144  alignment feature ( FIG. 8 ) that establishes a certain desired rotational alignment (about longitudinal centerline  58 ) between fluid exchanger  26  and breast receiver  22 . 
         [0049]    Although the invention is described with respect to a preferred embodiment, modifications thereto will be apparent to those of ordinary skill in the art. The scope of the invention, therefore, is to be determined by reference to the following claims: