Abstract:
A portable, electric breast pump has an electronic controller adapted to track time and operate a solenoid to automatically maintain a predetermined suction and release rhythm as a function of time to mimic the natural sucking rhythm of an infant. Suction is produced by a continuously running diaphragm pump. A needle valve permits user vacuum level adjustment, but no other user control is required. A flapper valve in the top of the bottle reduces the suction rise time but incorporates a fixed amount of leakage to build a small amount of bottle pressure for pulling collected milk into the bottle during the release portion of the cycle. An improved bulkhead design helps to keep milk from entering the diaphragm pump if the unit is shaken or turned on its side.

Description:
This is a continuation of U.S. application Ser. No. 09/687,452, filed Oct. 13, 2000 now U.S. Pat. No. 6,673,036 and claiming priority from provisional application No. 60/159,344, filed Oct. 13, 1999. 
    
    
     BACKGROUND 
     This invention relates generally to devices and methods for drawing milk from a human breast. 
     Many mothers rely on pumps to extract their breast milk. The more such pumps are automated and simulate the natural sucking rhythms of an infant, the easier it can be for a mother to relax and allow her milk to “let down” and flow. Pumps in common use include manually operated mechanical pumps. Which require the user to repeatedly manipulate a lever or pedal to produce suction. and electrical pumps, which run on either DC battery or AC line voltage. 
     With portable pumps, especially ones with electric vacuum sources, it is preferred that the milk only enters the easily washed storage bottle connected to the breast hood. Particularly, milk should be kept from inaccessible vacuum passages and pumping hardware which is not easily cleaned. Many electric pumps, for instance, come with instructions that caution against allowing the pump to tip over or lie on its side with milk in the bottle, as the milk may flow through the vacuum port and into the pumping chamber. 
     SUMMARY 
     According to one aspect of the invention, a receptacle bulkhead for a portable pumping device for drawing milk from a human breast is provided. The pumping device has a milk receptacle and a vacuum source for applying suction to a hood configured to receive the breast, and the receptacle bulkhead is configured to separately connect the vacuum source and the hood to the milk receptacle. The bulkhead has a housing defining an internal chamber, a milk inlet conduit, a milk outlet conduit and a vacuum port. The milk inlet conduit provides communication between the hood and the internal chamber and extends from one side of the internal chamber with the portable pumping device in an upright position for normal use, such that entering milk tends to flow along a lower side of the conduit. The milk outlet provides communication between the internal chamber and the milk receptacle, and is disposed at a lower end of the internal chamber with the portable pumping device in its upright position. The vacuum port provides communication between the vacuum source and the internal chamber through a vacuum inlet passage within the receptacle bulkhead. The vacuum inlet passage extends a distance along the milk inlet conduit and is separated from the lower side of the conduit, such that with the pumping device in its upright position milk entering from the hood will tend to avoid the vacuum inlet passage and, with the pumping device in a sideways position with the milk inlet conduit extending upward, milk from the receptacle will be inhibited from entering the vacuum inlet passage. 
     In a presently preferred construction, the internal chamber has a domed upper surface and the vacuum port is disposed at an upper apex of the domed upper surface. 
     The housing may be of a unitary molded piece of transparent plastic, for example, and may form a top for the milk receptacle, with the milk outlet making a threaded connection between the milk receptacle and the bulkhead housing. 
     Preferably, the vacuum inlet passage extends beyond the milk outlet toward the hood. 
     According to another aspect of the invention, a breast pump for drawing milk from a human breast includes a hood configured to receive the breast, a milk receptacle in communication with the hood for storing milk from the breast, a vacuum source for applying suction to the hood, and a one-way valve disposed between the hood and the milk receptacle. The valve includes a cup-shaped valve body with a hole through its bottom, and a flexible membrane flap. The flap is arranged to cover the hole through the valve body when suction is applied to the hood, inhibiting flow between the hood and the milk receptacle, such that milk from the hood is collected in the cup on top of the membrane flap, and to flex, under weight of the collected milk, to expose the hole when hood suction is released, allowing the collected milk to flow from the valve body into the milk receptacle. 
     In one preferred embodiment, the valve cup is retained in a bulkhead constructed to provide communication between the hood, the milk receptacle, and the vacuum source, with the valve cup engaging the bulkhead at an interface constructed to provide a predetermined amount of air leakage around the valve, between the bulkhead and the milk receptacle, when suction is applied to the hood. 
     According to another aspect of the invention, a breast pump for drawing milk from a human breast includes a hood configured to receive the breast, a milk receptacle in communication with the hood for storing milk from the breast, a vacuum source for applying suction to the hood, a bulkhead constructed to provide communication between the hood, the milk receptacle, and the vacuum source, and a one-way valve disposed between the hood and the milk receptacle and engaging the bulkhead at an interface. The valve is constructed to close when suction is applied to the hood, and to open when suction is released to let collected milk flow into the milk receptacle. The interface between the valve and the bulkhead is constructed to provide a predetermined amount of air leakage around the valve, between the bulkhead and the milk receptacle, when suction is applied to the hood, for transferring vacuum to the milk receptacle during suction for pulling collected milk into the milk receptacle when suction is released. 
     Other aspects of the invention include methods of using the above-described pumping devices to extract milk from a human breast. For example, the method of using the pumping device of the first aspect of the invention includes holding the hood of the pumping device against the breast, and activating the pumping device to begin applying repeating pressure cycles to the breast to extract milk. The controller of the pumping device regulates the frequency and intervals of the pressure cycles to be effectively independent of suction, flow rates and power levels. 
     The improved bulkhead design of the invention can help to avoid milk entering the main body of the pump and pumping chamber, facilitating cleaning. Other features and advantages will be apparent from the following embodiment description. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIG. 1  illustrates the use of a portable breast pump. 
         FIG. 2  is a perspective view of the breast pump. 
         FIG. 3  is an expanded view of the major components of the pump. 
         FIG. 3A  is an enlarged view of area  3 A in FIG.  3 . 
         FIG. 4  is a perspective view of the lower end of the valve cup, showing the flapper membrane. 
         FIG. 5  is a top view of the main body of the breast pump. 
         FIG. 6  is a cross-sectional view of the main body, taken along line  6 — 6  in FIG.  5 . 
         FIG. 7  is a top view of the bulkhead of the breast pump. 
         FIG. 8  is a cross-sectional view of the bulkhead, taken along line  8 — 8  in FIG.  7 . 
     
    
    
     DETAILED DESCRIPTION 
     Referring first to  FIG. 1 , electric breast pump  10  is operated by holding the hood  12  of the pump against the breast and turning the pump on. Once turned on, pump  10  automatically cycles vacuum pressure applied to the breast to simulate the natural sucking rhythms of an infant. Milk extracted from the breast flows from hood  12  into a removable storage bottle or receptacle  14 . When turned off, the pump automatically releases hood vacuum for easy removal from the breast. 
     Referring now to  FIG. 2 , the main body  16  of pump  10  forms a graspable handle  18  for holding the pump with one hand during operation. Bottle  14  is connected to body  16  and hood  12  by a 3-way adaptor or vacuum bulkhead  20 , through which milk flows from hood  12  to bottle  14  through a valve cup  40 . The bottle and hood are suspended from pump body  16  by bulkhead  20 . which is released from body  16  by depressing a release plunger  22 . The only two user operation controls provided on the pump are an on/off button  24  and a vacuum level adjustment dial  26 , which is located on handle  18  for convenient manipulation during operation. Pump  10  is battery-operated, and a power jack  28  at the base of the pump is provided for connecting the pump to household current through a typical AC/DC converter (not shown). 
     A light-emitting diode (LED)  30  at the top of the pump helps to identify various operation modes. A blinking light during battery operation indicates that the batteries are running low on power. If battery use is continued past a predetermined low voltage level, the pump will automatically cease pumping and will release hood vacuum and turn off LED  30 . A fast blinking LED  30  while the pump is plugged into an AC power outlet indicates that the batteries are being controllably drained to a very low voltage (or “refreshed”) to improve recharge-ability. A slow blinking light while plugged in means that the batteries are being recharged. When fully recharged, LED  30  will be turned off. 
     Hood  12  is a flexible breast shield that is provided with inner bumps  32  that are designed to stimulate milk let down by creating a massaging effect during pumping pressure cycles. 
     Referring to  FIG. 3 , a nipple adaptor  34  is designed to be placed within hood  12  to accommodate smaller breasts or nipples, and is provided with additional massaging bumps  32 . The nose of hood  12  is releasably pressed over an inlet conduit  36  of bulkhead  20  to form a vacuum-tight connection. Bulkhead  20  is molded of clear plastic and has a lower skirt  38  that makes a threaded connection with the top of bottle  14 . A typical gasket (not shown) between bulkhead  20  and the upper edge of the top of bottle  14  makes the connection between bulkhead  20  and bottle  14  vacuum-tight. 
     Before bulkhead  20  is threaded onto bottle  14 , a valve cup  40  is releasably pressed into an inner bore of bulkhead  20  just above skirt  38 . A small molded bead  42  about the periphery of the circular top of valve cup  40  provides a seal between the bulkhead  20  and cup  40  about most of the periphery of the cup. A larger bead  44  farther down on cup  40  limits the distance cup  40  is pressed into bulkhead  20  and helps to keep the cup from becoming cocked within the bulkhead. As shown in FIG.  3 A. an arched, molded protrusion  46  extends axially across sealing bead  42  at one location about the cup perimeter, and projects radially outward from the side wall of the cup at its midpoint slightly farther than bead  42 , creating two small air leak paths across the connection between bulkhead  20  ( FIG. 3 ) and valve cup  40 . A corresponding groove  48  through stop bead  44  ensures that bead  44  will not form a controlling seal between the bulkhead and valve cup. In effect, a fixed and small vacuum leak is created around the valve cup, the benefits of which are discussed below. Alternative air leak path constructions may be employed, such as a slit through bead  42  or a fixed orifice molded or pierced through the side of the valve cup body, for instance. Also, instead of providing air leak features on the valve cup, appropriate features may be provided on the inner surface of bulkhead  20  where the valve cup engages the bulkhead. 
     Referring back to  FIG. 3 , when assembled valve cup  40  extends from bulkhead  20  down into bottle  14  and forms a one-way valve between the bulkhead and the bottle. When vacuum is applied to the interior of bulkhead  20  and valve cup  40 , a flexible flapper membrane  50  is drawn up to cover two slots  52  through the bottom of valve cup  40 , thereby enabling the vacuum source of the pump to more quickly produce the desired level of vacuum at the breast by not evacuating the volume of bottle  14  below valve cup  40 . During suction, milk flowing from hood  12  is collected in the valve cup. Upon release of vacuum pressure, the weight of collected milk in cup  40  helps to lower membrane  50  to let the collected milk drop into bottle  14 . At the start of the next vacuum cycle, membrane  50  is again drawn against the lower surface of cup  40  to cover slotted holes  52  and enable rapid increase in hood vacuum. 
     The lower end of valve cup  40  is illustrated in FIG.  4 . The primary structure of cup  40  is molded of semi-rigid polypropylene with a bottom surface forming a gentle arc such that milk is directed toward a slot  52  formed through the lower surface of the cup near each of two opposite sides. Membrane  50  is formed of a resilient, flexible material and staked, snapped or otherwise fastened to the primary structure of the cup at its midpoint, such that it forms two freely cantilevered flaps corresponding to the two holes  52  in the bottom of the cup. In the illustrated embodiment, the membrane is of molded silicone rubber having a nominal thickness of about 0.025 inch (0.6 millimeter) and an extent of about ¾ inch by ¾ inch (20 millimeters per side). A molded projection from the upper surface of the membrane (not shown) is snapped into a corresponding hole in the bottom of the valve cup body. Raised bumps  54  opposite slots  52  help to add rigidity to the membrane flaps and help to avoid sucking the membrane too far into slots  52 . 
     Referring back to  FIGS. 3 and 3A , release of collected milk from valve cup  40  is aided by the fixed, small amount of leakage built into the seal between the valve cup and bulkhead  20  (described above with reference to the intersection of seal bead  42  and projection  46  of the valve cup). During the suction portion of the pumping cycle, during which the interior of bulkhead  20 , valve cup  40  and hood  12  are evacuated, the fixed leakage about valve cup  40  enables a slow, progressive evacuation of air from the interior of bottle  14 , creating by the end of the suction cycle a low level of vacuum within the bottle. When the vacuum in the bulkhead is rapidly released at the end of the suction cycle, the low level of vacuum in bottle  14 , below valve cup  40 , helps to pull membrane  50  away from slots  52  and to pull collected milk through the bottom of the valve cup and into bottle  14 , such that valve cup  40  is quickly emptied before the next suction cycle. The amount of leakage designed into the seal between valve cup  40  and bulkhead  20  must be small enough to not inhibit a sufficiently rapid increase in vacuum (i.e., reduction in absolute pressure) in bulkhead  20  and at the breast at the beginning of the suction cycle, but large enough to form enough vacuum in the bottle to deflect membrane  50  away from the bottom of the valve cup and pull the collected milk from the valve cup during the release cycle. In this sense, the controlled leakage acts as a low-pass pressure filter between breast and bottle. The transparent bulkhead  20  and valve cup  40  enable the mother to watch the cyclic filling of the valve cup to monitor the rate and progress of milk extraction. 
     Referring to  FIGS. 5 and 6 , the main body  16  of the breast pump  10  has a housing comprising left and right halves  54  and  56 , an upper button plate  58  and a base plate  60 . The handle of the unit accommodates five 1.5-volt rechargeable batteries  62  (shown also in FIG.  3 ), which are held in place by a removable battery cover  64  and threaded fastener  66 . Other major internal components illustrated in  FIG. 6  include the pump controller  68  in the form of a printed circuit board with discrete mounted components, an electric pump motor  70 , a diaphragm pump  72 , a needle valve  74  for adjusting pump vacuum level, and a solenoid  76  for releasing pump pressure. 
     When the unit is turned on, by pushing power button  24  to activate a power switch  78  mounted on the controller circuit board, motor  70  is energized to continuously run pump  72  until turned off, either by again pushing power button  24  or automatically by controller  68 . An eccentric cam  80  translates rotary motion of the motor rotor into reciprocating motion of the push rod of diaphragm pump  72 . Diaphragm pump  72  operates as a typical diaphragm pump, sucking air from valve manifold  82  through a flexible hose  84  during one half of each stroke cycle, and pushing air out of an outlet  86  during the other half of each stroke cycle. With the pump fully assembled, valve manifold  82  provides open parallel pneumatic communication between diaphragm pump  72 . the bulkhead  20  (shown in  FIG. 2 , for instance), and needle valve  74 . Connection to needle valve  74  is made by flexible tube  88 . A release hole (not shown) in the side of manifold  82  is normally covered by the spring-loaded plunger  90  of solenoid  76 , enabling diaphragm pump  72  to build vacuum pressure. When solenoid  76  is energized, plunger  90  retracts against its spring, exposing the manifold release hole to quickly release vacuum pressure at the breast. When solenoid  76  is again de-energized, its plunger reseals the release hole and the continuously running diaphragm pump again builds a suction pressure. Alternatively the solenoid may be configured to cover the release hole of the manifold when energized, and automatically retract to release vacuum when de-energized. 
     Needle valve  74  is adjusted by turning dial  26 , thereby adjusting the extension of screw  92  and the corresponding depression of the plunger of the needle valve, thereby adjusting the controlled vacuum leakage through the needle valve from manifold  82 . Alternatively an adjustable pressure relief valve may be employed, which would permit vacuum leakage only when an adjustable vacuum level is exceeded. 
     Bulkhead release button  22  operates a bulkhead attachment/release mechanism similar to that of the “1068 Breast Pump” marketed by The First Years Inc. in Avon, Mass. The attachment/release mechanism allows the bulkhead to be quickly and sealingly attached to the pumping system by simply pushing the bulkhead upward until it snaps into place. Releasing the attached bulkhead requires depressing release button  22 . 
     Controller  68  contains a timer circuit for controlling the frequency and interval durations of the repeating vacuum pressure cycles based on time. In the illustrated embodiment, the timer circuit hardware is included in an EPROM integrated circuit chip NT66P20 that is programmed to provide the desired control functions. Other devices and methods of monitoring time, such as with various sorts of oscillators, are also known to those of skill in the art of circuit design. Preferably, the method of monitoring (i.e., measuring or tracking) time is essentially independent of pump pressures, flow rates, motor or pump temperatures, and expected variations in physical component characteristics and conditions, such that the desired sucking rhythm is accurately maintained, even as battery voltages begin to drop. 
     Controller  68  has four primary functions. First, it provides constant power to motor  70  while the unit is turned on. Second, it controls the timing of solenoid  76  to establish and maintain the alternating suction/release rhythm. Third, it operates indicator  30  to communicate information about the operational status of the unit. Fourth, it monitors battery voltage and initiates controlled discharge and recharge as appropriate. Fifth, it initiates a controlled automatic shut-down when necessary. 
     The first three controller functions have already been discussed. When the unit is turned off but plugged into an AC outlet, controller  68  monitors battery voltage to determine whether or not to recharge, or controllably discharge and then recharge, the batteries. In addition, the controller  68  monitors battery voltage every 3 seconds during motor operation. When battery voltage is below a first threshold but above a lower, second threshold, the controller causes the illuminated LED  30  to blink. To avoid premature LED blinking from transient low voltage conditions, controller  68  must identify a low voltage condition at least 30 times before causing LED  30  to blink. When voltage drops below the second threshold for at least 4 to 6 consecutive voltage measurements, controller  68  determines that battery voltage has fallen too low to permit safe, continued operation of the unit within desirable performance specifications and initiates an automatic shutdown. Before shutting down completely, controller  68  first energizes solenoid  76  for 2 seconds to release any residual vacuum at the breast to facilitate removal of the breast hood. 
     Referring to  FIGS. 7 and 8 , bulkhead  20  is unitarily molded of clear polycarbonate and provides a sealed hydraulic connection between the pump vacuum source (through an upper vacuum port  94 ), the breast hood (through a milk inlet  96 ) and the bottle (threadably connected to lower bulkhead skirt  38 ). Bulkhead  20  defines an internal chamber  98  that is evacuated during, the suction portion of the pressure cycle. The milk inlet conduit  100  has a molded groove  102  for receiving an internal rib of the breast hood (not shown) and a stop shoulder  104 . The milk inlet extends from one side of internal chamber  98  when the bulkhead is mounted on the pump in an upright position for normal use (skirt down), such that entering milk tends to flow along lower side  106  of inlet conduit  100 . Notably, communication between chamber  98  and vacuum port  94  is through a vacuum inlet passage  108  that extends a distance toward and along milk inlet conduit  100 . Vacuum inlet passage  108  is well above the lower side of the conduit, such that with the pumping device in its upright position milk entering from the hood will tend to avoid the vacuum inlet passage. With the pump in a sideways position with milk inlet conduit  100  extending upward, such as if the unit falls onto its side opposite the breast hood, the open end of inlet passage  108  is high enough to prevent milk from the bottle from flowing into the vacuum inlet passage  108  and contaminating or wetting components of the pump vacuum source. Additionally, inner baffle  110  helps to protect the vacuum source from milk spray or splash, such as if the unit is inadvertently shaken or dropped. Bulkead  20  may be employed to advantage with many types of electric or manual breast pumps, and is particularly useful with portable units that are prone to being dropped, tilted or shaken. 
     Other embodiments are within the scope of the invention, as defined by the appended claims. For example, rhythm adjustment means may be added, such as in the form of dials or screws, for adjusting the timing of the suction and release portions of the cycle as controlled by the controller.