referring to fig1 apparatus 10 is provided for expressing milk from one breast , or from two breasts simultaneously . the apparatus 10 includes a first collector or expresser 12 and a second expresser 14 . it is likely that both expressers would generally be used , but only one expresser could be used , if desired , preferably by disconnecting the vacuum line from the unused expresser and covering the unused vacuum port of the pump with a cap ( not shown ). a pump 16 is connected to both expressers 12 , 14 through vacuum lines 18 , 20 , and air pressure lines 22 , 24 . the vacuum and pulsation lines can be configured in any suitable way . in fig1 vacuum hoses 18 a , 20 a and pressure hoses 22 a , 24 a are connected to the pump 16 and a connector 17 . vacuum hoses 18 b , 20 b and pressure hoses 22 b , 24 b are connected to the other end of the connector 17 and the expressers 12 , 14 with adapters 23 ( fig2 ), if needed . the connector 17 has openings for the lines 18 , 20 , 22 and 24 , and a throat 19 which connects the vacuum lines 18 , 20 to each other , creating a common vacuum at the expressers 12 , 14 , as seen in fig1 . a threaded needle valve 21 in the throat 19 permits easy adjustment of the vacuum by venting atmospheric air into the system as desired . the connector 17 can be secured to a housing , if desired , to provide easy vacuum and pressure transmission through the housing . the pump 16 creates a vacuum which engages the breasts , and contributes to drawing the milk from the breasts . the pump also creates reciprocating compression and release pressure pulsation around the areola and some or all of the nipple , as will be seen . the pump 16 can be powered by line voltage , a battery , manually or the like . the expressers 12 , 14 are shown in greater detail in fig2 and 5 . each expresser includes a manifold 26 , a cup assembly 28 which fits over a breast , a cap 30 , a filter 31 ( fig5 ), a sealing device 33 a such as a wipe washer , o - ring or the like , and a collection vessel 34 . gaskets 33 b and 33 c are also included , to better seal the vacuum system . a valve 36 can be included , though it is not necessary . the collection vessel can be a bottle made of plastic - like material or the like or a bag , and can be oriented at an obtuse angle with respect to the cup assembly , as shown . the manifold 26 includes an opening 38 which is preferably threaded , so that a collection vessel such as a plastic milk bottle can be threadedly secured to the manifold 26 , with the valve 36 . the valve 36 is preferably a one - way check valve such as a duck bill valve or the like . when using the valve 36 , the gasket 33 c is not needed because the valve 36 seals the opening 38 . a vent 37 in the manifold 26 is helpful because it keeps the collection vessel 34 at atmospheric pressure when the valve 36 is used . however , it is also possible to eliminate the valve 36 , in which case there is also no need for the vent 37 . a vacuum is applied to the expresser through a port 42 in the cap 30 , and is drawn through a vacuum path in the manifold 26 through an outlet opening 44 in the top of the manifold . the vacuum is drawn through an internal orifice 46 to the opening 38 in the midsection of the vacuum path , which is beneath the port 42 and the cup assembly 28 . the vacuum tends to close the valve 36 , which in conjunction with the vent 37 , prevents a substantial buildup of vacuum in the collection vessel 34 . the vacuum is drawn from the opening 38 to a manifold vacuum inlet 40 through a channel 50 . the vacuum inlet 40 forms a cup assembly opening that is in communication with a milk outlet port 48 in the cup assembly 28 . when milk is drawn from the breast , the milk passes through the channel 50 under the force created by the vacuum , but most of the milk drops into the valve 36 through the force of gravity , and does not enter the orifice 46 . cleaning is easier because milk is not drawn into the vacuum path beyond the collection vessel 34 . when sufficient milk collects in the valve 36 , the weight of the milk forces the valve open , which releases the milk into the collection vessel 34 . because the milk falls down , the vacuum lines are not contaminated . in this manner , the milk is collected without contaminating the vacuum lines 18 , 20 ( fig1 ). the cup assembly 28 has a milk inlet port 52 in addition to the outlet port 48 . the components of the cup assembly 28 include a bell housing 54 , a donut shaped pad 56 , and a flexible liner 58 , shown disassembled in fig4 . the cup assembly 28 also has an air pressure pulsation port 60 which forms part of a pressure path and allows pressurized air to enter a space 62 between the case bell housing 54 and the liner 58 . the cup assembly 28 is assembled by placing the donut shaped pad 56 in the housing 54 as shown , and does not need further securement . the pad 56 is preferably made of a suitable foam material which is sized to fit snugly in the housing 54 . however , the pad 56 can be easily removed by placing a finger through the opening in the ring and pulling the ring out . the liner 58 is installed in the cup assembly 28 by securing an end 63 to the liner 58 in a groove 64 formed in the housing 54 ( fig2 and 4 ). the end 63 and groove 64 are shaped to provide locking press fit type of securement . the liner could also be affixed to the housing 54 by heat or chemical bonding . the liner 58 extends from the groove 64 over and around the pad 56 and inside of the housing 54 to a bottom end 66 of the housing 54 . an end 68 of the liner 58 is inserted into a groove 70 near the end 68 for securement in a press fit fashion . the liner 58 can be any suitable shape , including the shape shown in fig2 which includes a relatively narrow section 72 near the inlet opening 52 , and a wider section 74 between the section 72 and the outlet end 48 of the cup assembly 28 . this shape places more pressure around the areola region of the breast , while placing less pressure on the nipple itself . by sealing the liner to the case at both ends , the assembly can be washed without taking the liner off , if a cleaning cap 75 is placed over the pressure inlet 45 ( fig4 ). the cup assembly 28 can be press fit into a circular groove 76 in the manifold 26 , seen in fig5 . the groove 76 is formed by an outside wall 78 and an inside boss 80 . the boss 80 can extend outwardly as far as desired , and can be any suitable shape , such as circular , triangular , square , rectangular , elliptical , hexagonal , etc . since the boss 80 is hollow and prevents the liner 43 from collapsing under outside air pressure , the boss 80 protects any part of the nipple which is inside the boss from a pinching action caused by pressure when the liner is collapsed , as seen in fig6 . abrasion is avoided because there is more room for breast extension during milk expression . the boss 80 also keeps the throat of the cup assembly open , so that the flow of milk is not inhibited . the cap 30 ( fig2 and 5 ) includes an air pressure / pulsation channel 82 which extends from a pressure inlet 84 to the port 60 , as well as the port 42 for the vacuum path . the cap 30 can be press fit over the manifold opening 44 and the cup assembly air pressure / pulsation port 60 , and can be easily removed . when installed , the cap 30 further secures the cup assembly in the manifold , but both the cap and the manifold can be removed without tools for cleaning purposes . the filter 31 , if used , further prevents liquids , fats and solid components in the milk from entering the vacuum lines and the pump . the filter 31 is preferably permeable to air flow when dry and also when wet , which can happen if milk contacts the filter . thus , if the filter becomes wet due to milk and / or water , air can still pass through the filter because the filter remains permeable to air . an example of such a filter is versapor r1200 ( part no . 66393 ) by pall corp . referring again to fig1 the pump 16 has two halves 104 , 106 secured together by screws or the like 108 to form a chamber 110 . the screws 108 also secure a movable diaphragm 112 in place . the diaphragm 112 divides the chamber 110 into two halves 110 a , 110 b . the diaphragm 112 is oscillated in a back and forth manner by a motor 114 . about 41 - 65 pulsations per minute at the breast ( one pulsation being the result of both a back and forth motion of the diaphragm ) are believed to produce suitable results , with about 52 pulsations per minute producing good results . the motor can be secured to the housing by bolts 116 or the like . the motor 114 can be a stepper motor , which is one form of a linear actuator , which has a shaft 118 . the shaft 118 moves in and out of the motor 114 in the axial direction without rotation . the shaft 118 is threaded , and is moved by a rotating threaded ring 120 , which is similar to a nut . rotation of the ring 120 moves the shaft 118 linearly . in this manner , the shaft 118 can move the diaphragm 112 back and forth essentially directly , without large , complex linkages . the distal end of the shaft 118 can be guided by an opening 122 in an end cap 124 . the end cap 124 is secured by bolts 126 . the pump 16 also has vacuum outlets 128 , 130 in the chamber 110 , on opposite sides of the diaphragm 112 . the vacuum lines 18 , 20 are connected to the vacuum outlets 128 , 130 . check valves such as duck bill valves 136 , 138 control the vacuum and pumping operation , and exhaust valves 140 , 142 release the pressure created in the chamber halves 110 a , 110 b by the movement of the diaphragm 112 . however , some of the pressure generated by the diaphragm is transmitted through the pressure lines 22 , 24 to the collectors 12 , 14 . the pressure forces the liners 58 against the breasts ( see fig6 ), which further stimulates release of milk . while the vacuum is fairly continuous , though , the pressure pulsates , in part because the pressure is quickly bled through vents 143 in the pressure lines 22 , 24 . in fact , when the diaphragm moves away from a pressure line 22 , or 24 , air is drawn out and a partial vacuum can be created . [ 0052 ] fig7 shows the effect of adequately vented pulsation pressure on the vacuum supplied to the liner . the pump 16 generates a vacuum v sys . without pulsation pressure , the vacuum is fairly steady at v sys . when pressure pulses are applied to the outside of the liner , though , the vacuum periodically increases to v peak . those periodic increases stimulate milk production with less discomfort and a lower v sys than is needed if pressure pulses are not applied . preferably , a minimum v sys of 0 . 5 ″ mercury is maintained during use , and the maximum vacuum v peak does not exceed 5 ″ mercury . the maximum vacuum v peak is preferably 3 . 0 ″- 4 . 1 ″ mercury . however , the maximum differential between v sys and v peak is preferably between 1 ″ and 4 . 5 ″ mercury . the vents 143 are sized to obtain a desired v peak , and avoid stalling due to overload . if the vents are too small , v peak will be too high and stalling could occur . if the vents are too large , v peak will be too low . the device is light weight , portable and compact because large motor linkages are eliminated . wear is also reduced by simplifying the power train in this manner . the motor 114 can be any suitable device which creates a fairly self - contained drive system which is relatively small in size and fairly quiet . in fact , the motor can be an ordinary motor 114 with a threaded rotating shaft 146 , as seen in fig8 . in that embodiment , a fixed ring 148 is attached to the diaphragm . the ring 148 is also threaded , so when the shaft 146 rotates clockwise and counter - clockwise , the diaphragm 112 moves back and forth . the motor can be controlled in any suitable manner , such as the control system 150 shown in fig9 . an application specific integrated circuit or the like has a microprocessor 152 and a rom 154 , programmed to cause a motor driver 156 to set the desired rate of rotation and the direction of rotation of the motor . the rotation rate , as well as the timing of the back and forth motion of the diaphragm , can be controlled in this manner . the diaphragm 112 can be any suitable configuration , such as that shown in fig1 which features a flat stiff middle section flanked by soft corrugations . another design is shown in fig1 and 11 , where a diaphragm 158 has a plurality of rings 160 joined by corrugations 162 . in use , power is applied to the pump 16 , and the expressers 12 , 14 are placed over the breasts . the vacuum v sys created by the pump 16 secures the expressers 12 , 14 on the breasts and helps draw milk from the breasts . the pressure pulsations massage and compress the breasts to stimulate milk production , and reduce the amount of vacuum needed to collect the milk . the air pressure lines are vented to obtain strong pulses without overloading the system . this reduces discomfort to the breasts . the device can be easily disassembled without tools , cleaned and reassembled . the many advantages of this invention are now apparent . the pulsation pulses stimulate milk production , without overloading the system due to excessive pressure build - up in the pressure lines . cleaning is more convenient because milk does not enter the vacuum lines . moreover , the entire collector can be easily disassembled for cleaning and reassembled without tools . the bosses in the expressers protect the end of the nipple from irritation , which is comfortable . moreover , the entire pump is small , lightweight and relatively quiet . while the principles of the invention have been described above in connection with a specific apparatus and applications , it is to be understood that this description is made only by way of example and not as a limitation on the scope of the invention . for example , various aspects of the invention could be used to milk animals , as well as humans .
a device for expressing milk from one or more breasts has at least one , and preferably two expressers and a pump . the expressers each have a cup for fitting on the breasts and a cup outlet to which a vacuum created by the pump can be connected . the cups have a flexible liner which collapses around the breast to establish the vacuum . pulsating pressure is applied to the outside of the liner to increase the vacuum and stimulate milk production . the pressure is applied through lines which are vented to maintain adequate , consistent pressure pulses without stalling the pump .