Abstract:
An exemplary refill unit for a foam dispenser includes a container for holding a foamable liquid and a liquid pump connected to the container and an outlet nozzle. The liquid pump has a rigid back plate and a flexible membrane. The flexible membrane and the rigid back plate form an arcuate shaped liquid pump chamber. The rigid back plate has a liquid inlet located proximate a first end of the arcuate shaped pump chamber and a liquid outlet located proximate a second end of the arcuate shaped pump chamber. The liquid pump is actuated by progressive compression of the flexible membrane against the back plate.

Description:
RELATED APPLICATIONS 
       [0001]    This application claims priority to and the benefits of U.S. Provisional Patent Application titled Rotary Peristaltic Dome Pump, Ser. No. 62/245,629, filed on Oct. 23, 2015 and which is incorporated herein in its entirety by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates generally to dispenser systems, such as soap and sanitizer dispensers and refill units. 
       BACKGROUND OF THE INVENTION 
       [0003]    Dispensing systems, such as soap and sanitizer dispensers, provide a user with a predetermined amount of liquid or foam soap or sanitizer upon actuation of the dispenser. 
       SUMMARY 
       [0004]    Exemplary embodiments of dispensers, refill units, and pumps with variable output are disclosed herein. 
         [0005]    An exemplary refill unit for a foam dispenser includes a container for holding a foamable liquid and a liquid pump connected to the container and an outlet nozzle. The liquid pump has a rigid back plate and a flexible membrane. The flexible membrane and the rigid back plate form an arcuate shaped liquid pump chamber. The rigid back plate has a liquid inlet located proximate a first end of the arcuate shaped pump chamber and a liquid outlet located proximate a second end of the arcuate shaped pump chamber. The liquid pump is actuated by progressive compression of the flexible membrane against the back plate. 
         [0006]    Another exemplary refill unit for a foam dispenser includes a container for holding a foamable liquid and a pump housing connected to the container. The pump housing has a back plate, a flexible membrane, and an outlet nozzle. The flexible membrane has a base that is accepted in a groove of the back plate. An arcuate shaped pump chamber is formed at least in part by the back plate and the flexible membrane. The arcuate shaped pump chamber includes a liquid inlet in the first end of the arcuate shaped pump chamber and a liquid outlet located in the second end of the arcuate shaped pump chamber. A liquid outlet valve is located in the liquid outlet, and an outlet nozzle extends from the liquid outlet. A foaming media is located at least partially in the outlet nozzle. One or more air inlet apertures are located downstream of the liquid outlet and upstream of the foaming media. 
         [0007]    Still another exemplary refill unit includes a container, a pump housing, a vent valve in the pump housing to vent the container, a rigid back plate, and a flexible membrane. The flexible membrane has a raised portion and a base portion. The base portion of the flexible membrane is secured to the rigid back plate. The raised portion of the flexible membrane forms an arcuate shaped pump chamber between the flexible membrane and the rigid back plate. A mixing chamber is included downstream of the arcuate shaped pump chamber and an outlet nozzle. 
         [0008]    An exemplary foam dispenser includes a housing, an air pump secured to the housing and an actuating mechanism secured to the housing. The actuating mechanism has a swipe gear secured to a motor. A refill unit is installed in the dispenser that has a container and a pump secured to the container. The pump has a flexible membrane and a back plate that form an arcuate pump chamber and an outlet nozzle. The swipe gear compresses the arcuate pump chamber only during actuation of the pump. 
         [0009]    Another foam dispenser includes a housing. An air pump and an actuating mechanism are secured to the housing. The actuating mechanism has a swipe gear secured to a motor. A refill unit is installed in the dispenser. The refill unit includes a container and a liquid pump secured to the container. The liquid pump has a flexible membrane and a back plate that form an arcuate pump chamber and an outlet nozzle. The swipe gear compresses the arcuate pump chamber only during actuation of the pump. The motor drives both the liquid pump and the air pump. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    These and other features and advantages of the present invention will become better understood with regard to the following description and accompanying drawings in which: 
           [0011]      FIG. 1  is a cross-section of an exemplary dispenser system having a refill unit; 
           [0012]      FIG. 2A  is a perspective view of an exemplary refill unit and actuation drive system; 
           [0013]      FIG. 2B  is a partial cross-section of the refill unit of  FIG. 2A ; 
           [0014]      FIG. 2C  is a partial cross-section of the refill unit of  FIG. 2A ; 
           [0015]      FIG. 2D  is a perspective view of the actuation drive assembly of  FIG. 2A ; 
           [0016]      FIG. 3A  is a perspective view of an exemplary dispenser system having a refill unit with the housing removed; 
           [0017]      FIG. 3B  is a partial cross-section of the refill unit of  FIG. 3A ; 
           [0018]      FIG. 3C  is a partial perspective view of the dispenser and refill unit of  FIG. 3A  with the swipe gear removed; and 
           [0019]      FIG. 3D  is a partial perspective view of an actuator drive assembly and the swipe gear that was not shown in  FIG. 3C . 
       
    
    
     DETAILED DESCRIPTION 
       [0020]      FIG. 1  illustrates an exemplary embodiment of a foam dispenser  100 . The cross-section of  FIG. 1  is taken through the housing  102  to show a liquid pump  120 , an air pump  130 , a container  116 , and an actuator  140 . The dispenser  100  includes a disposable refill unit  110 . The disposable refill unit  110  includes container  116 , liquid pump  120 , premix chamber  122 , and outlet nozzle  126 . The dispenser  100  may be a wall-mounted system, a counter-mounted system, an un-mounted portable system movable from place to place, or any other kind of dispenser system. The dispenser  100  can be configured to pump liquid only with the air pump  130  removed or deactivated. Other components may also be removed for use with liquid dispensers only. 
         [0021]    The container  116  forms a liquid reservoir that contains a supply of dispensable liquid within the disposable refill unit  110 . In various embodiments, the contained liquid could be for example a soap, a sanitizer, a cleanser, a disinfectant, a lotion, a foamable liquid, or other dispensable liquid. In the exemplary disposable refill unit  110 , the container  116  is formed by a rigid housing member. A vent (not shown) to vent the container  116  is included. A vent (not shown) may be included in a wall of the container, or may be included in the pump  120  connected to the container (e.g. vent port  218  and vent valve  219  of  FIG. 2B ). In other embodiments, the container  116  may be formed by a collapsible container and can be made of thin plastic or a flexible bag-like material, or have any other suitable configuration for containing the liquid without leaking. A vent is not needed with a collapsible container. 
         [0022]    The container  116  may advantageously be refillable, replaceable or both refillable and replaceable. In the event the liquid stored in the container  116  of the installed disposable refill unit  110  runs out, or the installed refill unit  110  otherwise has a failure, the installed refill unit  110  may be removed from the dispenser  100 . The empty or failed disposable refill unit  110  may then be replaced with a new disposable refill unit  110 . 
         [0023]    The refill unit  110  includes the liquid pump  120  that is in fluid communication with the container  116 . A collar  114  secures the liquid pump  120  to the container  116 . The collar  114 , which may be a separate component or may be an integrally formed part of the liquid pump  120 , may secure the liquid pump  120  to the container  116  by any means, such as, for example, a threaded connection, a welded connection, a quarter turn connection, a snap fit connection, a clamp connection, a flange and fastener connection, or the like. 
         [0024]    The outlet of the liquid pump  120  is in fluid communication with a premix chamber  122  that also receives air from the air pump  130  through an air delivery tube  134 . The premix chamber  122  is in fluid communication with an outlet nozzle  126 . 
         [0025]    In some embodiments, the liquid pump  120 , premix chamber  122 , and outlet nozzle  126  are part of the refill unit  110  and may be disposed of upon depletion of the liquid from the container  116 . The air pump  130  and air delivery tube  134  are secured to the dispenser  100  and are not disposed of while replacing the refill unit  110 . The concept of having a foam pump that has a liquid pump portion separable from an air pump portion may be referred to as a “split pump.” Exemplary split pumps are shown and described in U.S. Pat. No. 9,089,860 entitled “Bifurcated Foam Pump, Dispenser, and Refill Units”, which is incorporated herein by reference in its entirety. The air pump  130  is generically illustrated because there are many different kinds of air pumps which may be employed in dispenser  100 . Air pump  130  may be any type of air pump, such as a rotary pump, a piston pump, a fan pump, a turbine pump, a pancake pump, a diaphragm pump, or the like. 
         [0026]    In some embodiments, the refill unit  110  includes projections (not shown) that interface with a rotatable retention ring (not shown) on the interior of the housing  102 . These projections secure the refill unit  110  within the housing  102  and retain the liquid pump  120  in contact with an actuation assembly  144  of actuator  140  when the refill unit  110  is installed in the dispenser  100 . The retention ring is rotated to remove the refill unit  110  from the dispenser  100 . An exemplary embodiment is shown and described in U.S. Pat. No. 8,485,395 entitled “Dispenser Lock Out Mechanism”, which is incorporated herein by reference in its entirety. The refill unit  110  may be secured within the dispenser  100  by other means, such as, for example, a quarter turn connection, a threaded connection, a flange and fastener connection, a clamped connection, or any other releasable connection. In some embodiments, components of the actuator  140 , such as actuation assembly  144 , may be part of the refill unit  110 . In fact, many of the components of the actuator  140  may be part of the dispenser  100  or be part of the refill unit  110 . The actuation assembly  144  includes a swipe gear (not shown) similar to those described below and liquid pump  120  is similar to the liquid pumps described below. 
         [0027]    The dispenser  100  also includes a sensor  150  for detecting a users hand, a processor and memory (not shown), and a power source (not shown) such as one or more batteries. The dispenser  100  may include a power system, such as that described in U.S. Published Patent Application No. 2014/0234140 entitled “Power Systems for Touch Free Dispensers and Refill Units Containing A Power Source”, which is incorporated herein by reference in its entirety. 
         [0028]    During operation of the dispenser  100 , upon detection of a hand by sensor  150  foamable liquid is pumped from the container  116  by the liquid pump  120  into the premix chamber  122 . Simultaneously, air is drawn into the air pump  130  through an air inlet  132  and is pumped through the air delivery tube  134  into the air inlet  124  of the premix chamber  122  to mix with the liquid. The air and liquid mixture is then forced through foaming media (not shown) to dispense rich foam from the nozzle  126 . In one embodiment, foaming media includes one or more screens that generate high quality foam. Foaming media may also include porous members, sponges, baffles, or the like. An aperture  115  in a bottom plate  103  of the housing  102  allows foam dispensed from the nozzle  126  to exit the housing  102  for use by the user. 
         [0029]    The dispenser  100  contains one or more actuators  140  to activate the liquid pump  120  and the air pump  130 . As used herein, actuator, actuating members, or mechanism includes one or more parts that cause the dispenser  100  to move liquid, air or foam. Different actuators may activate the liquid pump  120  and air pump  130 , or one actuator may be used to activate both the liquid pump  120  and air pump  130 . In some embodiments, the actuator  140  includes an electric motor  141  that turns a drive train  142  (such as one or more gears as shown) that interfaces with the actuation assembly  144  that actuates the liquid pump  120  when turned. The electric motor  141  of actuator  140  may be an AC motor or a DC motor and may be powered by a standard electrical source, such as 115 VAC or by batteries. A second motor  143  activates the air pump  130  to pump air into the premix chamber  122  to generate foam. Although the actuators are shown as the electric motors  141 ,  143  for a hands-free dispenser system with touchless operation, they may be any kind of actuator capable of activating the liquid and air pumps  120 ,  130 , such as a manual lever, a manual pull bar, a manual push bar, a manual rotatable crank, an electrically activated actuator, or other means for actuating the liquid pump  120  and air pump  130 . 
         [0030]    The air pump  130  and actuators  140  may be connected to the housing  102  by any means. In an exemplary split pump embodiment, the electronics (not shown), air pump  130 , air delivery tube  134 , and actuators  140  are part of a pump house (not show) that is attached to the housing  102 . Assembling these components into the pump house allows for easier assembly of the dispenser  100  and ensures alignment of the components. 
         [0031]      FIGS. 2A, 2B, 2C, and 2D  illustrate an exemplary embodiment of a refill unit  210  and actuation drive system of an exemplary dispenser  200 . The dispenser  200  includes a housing, a sensor, batteries, and circuitry that are not shown for clarity. The refill unit  210  is removable from the dispenser  200  and includes a container  212 , a liquid pump  230 , and a nozzle  250 . The dispenser  200  includes an air pump  260  and an actuation assembly  270  for actuating the liquid and air pumps  230 ,  260 . In some embodiments, both the air pump  260  and liquid pump  230  of the dispenser  200  may be included in the refill unit  210 . When arranged as a split pump, the air pump  260  is secured to the dispenser  200  and is not removed when the dispenser  200  is refilled by replacing the refill unit  210 . The actuation assembly  270  may also be included in the refill unit  210  or may be secured to the dispenser  200 . 
         [0032]    The interior of the container  212  forms a reservoir  220  for holding foamable liquid. A neck  214  of the container  212  is received within a collar  216  of a container closure  234 . When the collar  216  is connected to the neck  214  of the container  212 , a liquid tight seal is formed between the closure  234  and the container  212 . The collar  216  may be connected to the container  212  by any means, such as, for example, a threaded connection, a welded connection, an adhesive connection, a snap fit connection, a friction fit connection, a quarter turn connection, or the like. The container  212  is non-collapsing and is formed by a semi-rigid plastic. The container  212  is vented through a vent valve  219  in a vent port  218  of the container closure  234 . In some embodiments, the container  212  is be formed by a collapsible container and can be made of thinner plastic or a flexible bag-like material, or have any other suitable configuration for containing the liquid without leaking and does not need a vent. 
         [0033]    The liquid pump  230  includes a pump body  232  and a semi-annular flexible actuation membrane  240  which is best seen in  FIG. 2C . The pump body  232  is connected to container closure  234  and the two are shown as separate components in  FIG. 2B , but may also be formed integrally as a single component. The pump body  232  has an outlet  236  and a rigid back plate  238 . The flexible actuation membrane  240  has a base  241 , a resilient actuation portion  242 , a first end  244 , a second end  246 , and a direction of actuation  248 . In some embodiments first end  244  has a surface that slopes upward to the top of the flexible actuation membrane  240 . In some embodiments second end  244  has a surface that slopes downward from the top of the flexible actuation membrane  240 . 
         [0034]    A groove  239  in the back plate  238  receives the base  241  of the flexible actuation member  240  forming an arcuate pump chamber  222  between the actuation membrane  240  and the back plate  238 . A liquid tight seal is formed between the base  241  of the actuation membrane  240  and the groove  239  of the back plate  238 . The flexible actuation membrane  240  and pump body  232  may be held together by any means, such as, for example, an adhesive, a friction fit connection, a projection and groove connection, through the use of another component to mechanically restrain the component, or the like. The flexible actuation membrane  240  may be made of any suitable flexible material, such as, for example, latex rubber, polyisoprene, TPE, silicone, EPDM rubber, nitrile rubber, or the like. In some embodiments the flexible actuation membrane  240  has a Shore D hardness of between about 30 and 60 durometer. 
         [0035]    A fluid passage  231  extends from inlet  221  through the container closure  234  and pump body  232  to fluidly connect the reservoir  220  and the pump chamber  222 . An outlet passage  233  extends through the portion  236  of pump housing  232  to fluidly connect the pump chamber  222  to a premix chamber  226  in the nozzle  250 . A one-way outlet valve  237  is disposed in the pump housing  232  downstream of pump chamber  222 . One-way outlet valve  237  prevents fluid from flowing up into the pump chamber  222  and container  212 . It also helps prevent liquid from leaking out of the refill unit  210  during storage. The one-way outlet valve  237  is shown as a duck-bill valve but may be any kind of one-way valve, such as, for example, a ball and spring valve, a poppet valve, a flapper valve, an umbrella valve, a slit valve, a mushroom valve, or the like. In some embodiments, one-way outlet valve  237  reduces the volume of the pump chamber  222  to increase the efficiency of the pump. 
         [0036]    In some embodiments, the outlet nozzle  250  includes a pump outlet valve  252 , an air inlet  254 , foaming media  256 , and an end cap  258 . The nozzle  250  is attached to the outlet portion  236  of pump housing  232  by any means, such as, for example, a threaded connection, a welded connection, an adhesive connection, a snap fit connection, a friction fit connection, a quarter turn connection, or the like. The outlet valve  252  is retained against the outlet portion  236  by the nozzle  250  and may be any kind of one-way valve, such as, for example, a ball and spring valve, a poppet valve, a flapper valve, an umbrella valve, a slit valve, a mushroom valve, a duck bill valve, or the like. The foaming media  256  is retained within the nozzle  250  by the end cap  258  and includes at least one mix media that generates high quality foam, such as, for example, one or more screens, porous members, sponges, baffles, or the like or combinations thereof. Foam is dispensed through a nozzle outlet  228  of the nozzle  250 . The end cap  258  is attached to the nozzle  250  by any means, such as, for example, a threaded connection, a welded connection, an adhesive connection, a snap fit connection, a friction fit connection, a quarter turn connection, or the like. In some embodiments any one of the outlet valves  237 ,  252  are not used. 
         [0037]    The air pump  260  includes an actuation shaft  262  and an air pump outlet  264 . The air pump  260  is connected to the nozzle  250  by an air delivery tube  266 . The air delivery tube  266  attaches to the air pump outlet  264  of the air pump  260  and an air inlet  254  of the nozzle  250 . An air inlet passageway  227  extends through the air inlet  254  to fluidly connect the air pump  260  to the premix chamber  226 . A one-way valve (not shown) may optionally be included in the air inlet  254  to prevent back flow of fluid from the premix chamber  226  if, for example, the nozzle outlet  228  of the refill unit  210  becomes clogged. 
         [0038]    The actuation assembly  270  includes a motor  272 , a first drive train  274 , a second drive train  275 , and a swipe gear  276 . In the illustrated embodiment, the motor  272  is an electric motor and may be an AC motor or a DC motor and may be powered by a standard electrical source, such as 115 VAC outlets or by batteries. The motor  272  has a drive shaft  273  that connects to the first and second drive trains  274 ,  275 . The first drive train  274  transmits power from the motor  272  to the swipe gear  276  to actuate the liquid pump  230 . The second drive train  275  transmits power from the motor  272  to the actuation shaft  262  of the air pump  260  to actuate the air pump  260 . The first drive train  274  also reduces the rotational speed of the motor  272  that is transmitted to the swipe gear  276  so that more than one rotation of the drive shaft  273  is required to rotate the swipe gear  276  through a complete rotation. In the illustrated embodiments, the first drive train  274  is a series of gears and the second drive train  275  is a flexible belt. In some embodiments, gears are used for both the first and second drive trains  274 ,  275 . Alternatively, two different motors (not shown) may be used to actuate the liquid and air pumps  230 ,  260 . 
         [0039]    When the refill unit  210  is installed in the dispenser  200  the liquid pump  230  is positioned so that rotation of the swipe gear  276  in the direction of actuation  248  will cause the swipe projections  277  to compress the actuation portion  242  and wipe across the actuation portion  242  of the actuation membrane  240 , and therefore, the pump chamber  222 . The first end  242  and second end  244  of the flexible actuation membrane  240  are rounded and/or tapered to provide a smooth transition for a swiping projections  277  of a swipe gear  276  during actuation of the liquid pump  230 . In some embodiments, projections  277  are formed as part of swipe gear  276 . In some embodiments, projections  277  are one or more rollers. In some embodiments, projections  277  have a sloped surface. In some embodiments, there are two projections  277 . In some embodiments, there are more than two projections  277 . As the swipe gear  276  is rotated, the swiping projections  277  progressively compress the actuation portion  242  of the actuation membrane  240  against the back plate  238  of the pump body  232  causing liquid in the pump chamber  222  to be forced through the outlet valve  237  into the outlet  224 . The actuation portion  242  of the membrane  240  expands to its original uncompressed position behind each swipe projection  277 , causing the pump chamber  222  to increase in volume, drawing in liquid from the reservoir  220  through the inlet  221 . As described above, the chamber valve  237  prevents fluid from leaking out of the pump chamber  222  when the membrane  240  is not compressed. In some embodiments, in between actuation cycles, the swipe projections  277  of the swipe gear  276  do not engage the actuation membrane  240 . This allows the actuation membrane  240  to be made from thermoplastic materials rather than thermoset materials. In some embodiments, one or more projections  277  always compress a portion of pump chamber  222  and the outlet valve(s) may not be needed. 
         [0040]    Rotation of the swipe gear  276  pushes liquid past the outlet valve  252  and into the premix chamber  226 . Simultaneously, the motor  272  causes the drive shaft  262  of the air pump  260  to rotate, pumping air through the air delivery tube  266  into the premix chamber  224  through the air inlet passageway  227 . 
         [0041]    The liquid flow rate from the liquid pump  230  may be different than the air flow rate of the air pump  260 . In some embodiments, the air to liquid ratio between the two pumps may be between about 1 to 1 and about 20 to 1, for example, the air to liquid ratio may be about 15 to 1, 10 to 1, 8 to 1, or 5 to 1. Continued actuation of the dispenser forces the air and liquid mixture out of the premix chamber  226  through the foaming media  256  to generate and dispense rich foam from the nozzle outlet  228 . 
         [0042]      FIGS. 3A, 3B, 3C, and 3D  illustrate an exemplary embodiment of a dispenser system  300 , a refill unit  310 , and an actuator drive assembly. The dispenser  300  includes a housing, a sensor, batteries, and circuitry that are not shown for clarity. The refill unit  310  is removable from the dispenser  300  and includes a container  312 , a liquid pump  330 , and a nozzle  350 . The liquid pump  330  is oriented in a generally horizontal direction, in contrast to the vertically oriented liquid pump  230  described above. The dispenser includes an air pump  360  and an actuation assembly  370  for actuating the liquid and air pumps  330 ,  360 . In some embodiments, both the air pump  360  and liquid pump  330  of the dispenser  300  may be included in the refill unit  310 . When arranged as a split pump, the air pump  360  is secured to the dispenser  300  and is not removed when the dispenser  300  is refilled by replacing the refill unit  310 . The actuation assembly  370  may also be included in the refill unit  310  or may be secured to the dispenser  300 . 
         [0043]    The interior of the container  312  forms a reservoir  320  for holding foamable liquid. A neck  314  of the container  312  is received within a collar  316  of a container closure  334 . When the collar  316  is connected to the neck  314  of the container  312 , a liquid tight seal is formed between the closure  334  and the container  312 . The collar  316  may be connected to the container  312  by any means, such as, for example, a threaded connection, a welded connection, an adhesive connection, a snap fit connection, a friction fit connection, a quarter turn connection, or the like. The container  312  is non-collapsing and is formed by a semi-rigid plastic. The container  312  is vented through a vent valve  319  in a vent port  318  of the container closure  334 . In some embodiments, the container  312  is be formed by a collapsible container and can be made of thinner plastic or a flexible bag-like material, or have any other suitable configuration for containing the liquid without leaking and does not need a vent. 
         [0044]    The liquid pump  330  includes a pump body  332  and a semi-annular flexible actuation membrane  340  which is best seen in  FIG. 3C . The pump body  332  is connected to container closure  334  and the two are shown as separate components in  FIG. 3B , but may also be formed integrally as a single component. The pump body  332  has an outlet  336  and a rigid back plate  338 . The flexible actuation membrane  340  has a base  341 , a resilient actuation portion  342 , a first end  344 , a second end  346 , and a direction of actuation  348 . 
         [0045]    A groove  339  in the back plate  338  receives the base  341  of the flexible actuation member  340  forming an arcuate pump chamber  322  ( FIG. 3C ) between the actuation membrane  340  and the back plate  338 . A liquid tight seal is formed between the base  341  of the actuation membrane  340  and the groove  339  of the back plate  338 . The flexible actuation membrane  340  and pump body  332  may be held together by any means, such as, for example, an adhesive, a friction fit connection, a projection and groove connection, through the use of another component to mechanically restrain the component, or the like. The flexible actuation membrane  340  may be made of any suitable flexible material, such as, for example, latex rubber, polyisoprene, TPE, silicone, EPDM rubber, nitrile rubber, or the like. In some embodiments the flexible actuation membrane  340  has a Shore D hardness of between about 30 and 60 durometer. 
         [0046]    A fluid passage  331  extends from inlet  321  through the container closure  334  and pump body  332  to fluidly connect the reservoir  320  and the pump chamber  322 . An outlet passage  333  extends through the portion  336  of pump housing  332  to fluidly connect the pump chamber  322  to a premix chamber  326  in the nozzle  350 . A one-way outlet valve  337  is disposed in the pump housing  332  downstream of pump chamber  322 . One-way outlet valve  337  prevents fluid from flowing up into the pump chamber  322  and container  312 . It also helps prevent liquid from leaking out of the refill unit  310  during storage. The one-way outlet valve  337  is shown as a duck-bill valve but may be any kind of one-way valve, such as, for example, a ball and spring valve, a poppet valve, a flapper valve, an umbrella valve, a slit valve, a mushroom valve, or the like. In some embodiments, one-way outlet valve  337  reduces the volume of the pump chamber  322  to increase the efficiency of the pump. 
         [0047]    In some embodiments, the outlet nozzle  350  includes a pump outlet valve  352 , an air inlet  354 , foaming media  356 , and an end cap  358 . The nozzle  350  is attached to the outlet portion  336  of pump housing  332  by any means, such as, for example, a threaded connection, a welded connection, an adhesive connection, a snap fit connection, a friction fit connection, a quarter turn connection, or the like. The outlet valve  352  is retained against the outlet portion  336  by the nozzle  350  and may be any kind of one-way valve, such as, for example, a ball and spring valve, a poppet valve, a flapper valve, an umbrella valve, a slit valve, a mushroom valve, a duck bill valve, or the like. The foaming media  356  is retained within the nozzle  350  by the end cap  358  and includes at least one mix media that generates high quality foam, such as, for example, one or more screens, porous members, sponges, baffles, or the like or combinations thereof. Foam is dispensed through a nozzle outlet  328  of the nozzle  350 . The end cap  358  is attached to the nozzle  350  by any means, such as, for example, a threaded connection, a welded connection, an adhesive connection, a snap fit connection, a friction fit connection, a quarter turn connection, or the like. In some embodiments any one of the outlet valves  337 ,  353  are not used. 
         [0048]    The air pump  360  includes an actuation shaft  362  and an air pump outlet  364 . The air pump  360  is connected to the nozzle  350  by an air delivery tube  366 . The air delivery tube  366  attaches to the air pump outlet  364  of the air pump  360  and an air inlet  354  of the nozzle  350 . An air inlet passageway  327  extends through the air inlet  354  to fluidly connect the air pump  360  to the premix chamber  326 . A one-way valve (not shown) may optionally be included in the air inlet  354  to prevent back flow of fluid from the premix chamber  326  if, for example, the nozzle outlet  328  of the refill unit  310  becomes clogged. 
         [0049]    The actuation assembly  370  includes a motor  372 , a first drive train  374 , a second drive train  375 , and a swipe gear  376 . In the illustrated embodiment, the motor  372  is an electric motor and may be an AC motor or a DC motor and may be powered by a standard electrical source, such as 115 VAC outlets or by batteries. The motor  372  has a drive shaft  373  that connects to the first and second drive trains  374 ,  375 . The first drive train  374  transmits power from the motor  372  to the swipe gear  376  to actuate the liquid pump  330 . The second drive train  375  transmits power from the motor  372  to the actuation shaft  362  of the air pump  360  to actuate the air pump  360 . The first drive train  374  also reduces the rotational speed of the motor  372  that is transmitted to the swipe gear  376  so that more than one rotation of the drive shaft  373  is required to rotate the swipe gear  376  through a complete rotation. To accommodate the horizontal orientation of the liquid pump  330  and actuation membrane  340 , a beveled gear  378  of the first drive train  275  engages a beveled portion of the horizontally oriented swipe gear  376 . An annular housing  379  is also included to retain the swipe gear  376  against the actuation membrane  340 . The annular housing  379  at least partially surrounds the actuation membrane  340  and the pump housing  332 . In some embodiments, the annular housing  379  may be secured to the pump housing  332 . In the illustrated embodiments, the first drive train  374  is a series of gears and the second drive train  375  is a flexible belt. In some embodiments, gears are used for both the first and second drive trains  374 ,  375 . Alternatively, two different motors (not shown) may be used to actuate the liquid and air pumps  330 ,  360 . 
         [0050]    When the refill unit  310  is installed in the dispenser  300  the liquid pump  330  is positioned so that rotation of the swipe gear  376  in the direction of actuation  348  will cause the swipe projections  377  to compress the actuation portion  342  and wipe across the actuation portion  342  of the actuation membrane  340 , and therefore, the pump chamber  322 . The first end  342  and second end  344  of the flexible actuation membrane  340  are rounded and/or tapered to provide a smooth transition for a swiping protrusions  377  of a swipe gear  376  during actuation of the liquid pump  330 . In some embodiments, protrusions  377  are rollers. As the swipe gear  376  is rotated, the swiping projections  377  progressively compress the actuation portion  342  of the actuation membrane  340  against the back plate  338  of the pump body  332  causing liquid in the pump chamber  322  to be forced through the outlet valve  337  into the outlet  324 . The actuation portion  342  of the membrane  340  expands to its original uncompressed position behind each swipe projection  377 , causing the pump chamber  322  to increase in volume, drawing in liquid from the reservoir  320  through the inlet  321 . In some embodiments, in between actuation cycles, the swipe projections  377  of the swipe gear  376  do not engage the actuation membrane  340 . As described above, the chamber valve  337  prevents fluid from leaking out of the pump chamber  322  when the membrane  340  is not compressed. This allows the actuation membrane  340  to be made from thermoplastic materials rather than thermoset materials. In some embodiments, one or more projections  377  always compress a portion of pump chamber  322  and the outlet valve(s) may not be needed. 
         [0051]    Rotation of the swipe gear  376  pushes liquid past the outlet valve  352  and into the premix chamber  326 . Simultaneously, the motor  372  causes the drive shaft  362  of the air pump  360  to rotate, pumping air through the air delivery tube  366  into the premix chamber  324  through the air inlet passageway  327 . 
         [0052]    The liquid flow rate from the liquid pump  330  may be different than the air flow rate of the air pump  360 . In some embodiments, the air to liquid ratio between the two pumps may be between about 1 to 1 and about 20 to 1, for example, the air to liquid ratio may be about 15 to 1, 10 to 1, 8 to 1, or 5 to 1. Continued actuation of the dispenser forces the air and liquid mixture out of the premix chamber  326  through the foaming media  356  to generate and dispense rich foam from the nozzle outlet  328 . 
         [0053]    While the present invention has been illustrated by the description of embodiments thereof, and while the embodiments have been described in considerable detail, it is not the intention of the applicants to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. Moreover, elements described with one embodiment may be readily adapted for use with other embodiments. Therefore, the invention, in its broader aspects, is not limited to the specific details, the representative apparatus and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of the applicants&#39; general inventive concept.