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 fig1 , 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 fig2 . it is seen in fig2 that the breast pump system shown in fig1 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 fig3 . in fig3 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 . a typical suction curve for expression mode is shown in fig4 . in fig4 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 fig4 is similarly achieved at the other levels shown in table 1 . fig5 is a typical cyclical suction curve for stimulation mode operation of the breast pump apparatus 10 . in fig5 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 fig6 - 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 fig6 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 fig4 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 fig4 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 fig1 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 fig4 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 .
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 .